Zygotic lethal gene: A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its earliest point.
A zygotic lethal gene is a mutated (changed) version of a normal gene essential to the survival of the zygote. The extent of the mutation can range from a change in a single base in the DNA to deletion (loss) of the entire gene.
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Zygote intrafallopian transfer (ZIFT)
Zygote intrafallopian transfer (ZIFT): A technique in which a woman's egg is fertilized outside the body, then implanted in one of her fallopian tubes. This technique is one of the methods used to overcome infertility, the inability of couples to produce offspring on their own.
First, the egg and the male sperm needed to fertilize it are harvested. Then the egg and the sperm are united in a petri dish, a multi-purpose glass or plastic container with a lid. If all goes well, the sperm fertilizes the egg, and the physicians then implant it in a fallopian tube. From there, nature takes its course, and the egg eventually is deposited by the fallopian tube into the uterus (womb) for development.
A zygote is the combined cell resulting from the union of sperm and egg. A zygote develops into an embryo. An embryo, a mass of cells with no recognizable human features, begins formation of a human body. After about seven or eight weeks, the embryo exhibits recognizable features such as a mouth and ears. At this stage, the developing human becomes known as a fetus. The word "zygote" is derived from the Greek word "zygon" (yoke).
The term "intrafallopian" means "inside the fallopian tubes." ("Intra," a Latin word, means "within" or "inside.") Thus, the term "zygote intrafallopian transfer" refers to the transfer of a zygote into a fallopian tube.
First, the egg and the male sperm needed to fertilize it are harvested. Then the egg and the sperm are united in a petri dish, a multi-purpose glass or plastic container with a lid. If all goes well, the sperm fertilizes the egg, and the physicians then implant it in a fallopian tube. From there, nature takes its course, and the egg eventually is deposited by the fallopian tube into the uterus (womb) for development.
A zygote is the combined cell resulting from the union of sperm and egg. A zygote develops into an embryo. An embryo, a mass of cells with no recognizable human features, begins formation of a human body. After about seven or eight weeks, the embryo exhibits recognizable features such as a mouth and ears. At this stage, the developing human becomes known as a fetus. The word "zygote" is derived from the Greek word "zygon" (yoke).
The term "intrafallopian" means "inside the fallopian tubes." ("Intra," a Latin word, means "within" or "inside.") Thus, the term "zygote intrafallopian transfer" refers to the transfer of a zygote into a fallopian tube.
Zygote
Zygote: The cell formed by the union of a male sex cell (a sperm) and a female sex cell (an ovum). The zygote develops into the embryo following the instruction encoded in its genetic material, the DNA.
The unification of a sperm and an ovum to form a zygote constitutes fertilization.
The unification of a sperm and an ovum to form a zygote constitutes fertilization.
Zygomycosis
Zygomycosis: A dangerous infection caused by a water-borne fungus. Zygomycosis is seen most often in patients who are already ill with diseases that cause wasting, such as AIDS or poorly controlled diabetes. If unchecked, the fungal infection can spread to the lungs and other organs, the blood, the eyes, and the brain. Treatment is two-fold: controlling the underlying condition, and attacking the infection with anti-fungal medications.
Zygomatic bone
Zygomatic bone: The part of the temporal bone of the skull that forms the prominence of the cheek.
The zygomatic bone is also known as the zygomatic arch, the zygoma, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
The zygomatic bone is also known as the zygomatic arch, the zygoma, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
Zygomatic arch
Zygomatic arch: The part of the temporal bone of the skull that forms the prominence of the cheek.
The zygomatic arch is also known as the zygomatic bone, the zygoma, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
The zygomatic arch is also known as the zygomatic bone, the zygoma, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
Zygoma
Zygoma: The part of the temporal bone of the skull that forms the prominence of the cheek.
The zygoma is also known as the zygomatic bone or arch, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
The zygoma is also known as the zygomatic bone or arch, the malar bone, the cheek bone and the yoke bone.
The word "zygomatic" comes from the Greek "zygon" meaning a yoke or crossbar by which two draft animals such as oxen could be hitched to a plow or wagon.
Zoophobia
Zoophobia: An abnormal and persistent fear of animals.
A phobia is an unreasonable fear that can cause avoidance and panic. Phobias are a relatively common type of anxiety disorder. Phobias can be treated with cognitive behavioral therapy using exposure and fear reduction techniques. In many cases, anti-anxiety or anti-depressant medication proves helpful, especially during the early stages of therapy.
Zoophobia is a term that encompasses fears of specific types of animals such as of spiders (arachnophobia), birds (ornithophobia), bees (apiphobia), etc. It is a zoo-ful of beastly phobias.
A phobia is an unreasonable fear that can cause avoidance and panic. Phobias are a relatively common type of anxiety disorder. Phobias can be treated with cognitive behavioral therapy using exposure and fear reduction techniques. In many cases, anti-anxiety or anti-depressant medication proves helpful, especially during the early stages of therapy.
Zoophobia is a term that encompasses fears of specific types of animals such as of spiders (arachnophobia), birds (ornithophobia), bees (apiphobia), etc. It is a zoo-ful of beastly phobias.
Zoophilia
Zoophilia: A sexual disorder involving an erotic attraction to animals or an abnormal desire to have sexual contact with animals. Zoophilia is one form of paraphilia (deviant sexual behavior).
Zoonotic transfer
Zoonotic transfer: The transmission of a disease from an animal host to a human. Infections transmitted from their animal host of origin to people may have a very severe impact. Hantavirus is an example. See also: Zoonosis; Zoonotic; Zoonotic disease.
Zoonotic disease
Zoonotic disease: Any disease that is spread from animals to people. There are many known zoonotic diseases, some of them very familiar such as Lyme disease and malaria. Less familiar zoonotic diseases (beginning with the letters "a" and "b") include alveolar hydatid disease (echinococcosis), ancylostoma infection (hookworm), ascariasis (intestinal roundworm infection), babesiosis (babesia infection), and baylisascaris infection (raccoon roundworm).
Zoonotic
Zoonotic: Pertaining to a zoonosis: a disease that can be transmitted from animals to people or, more specifically, a disease that normally exists in animals but that can infect humans. There are multitudes of zoonotic diseases.
Some examples include:
anthrax
ascariasis
brucellosis
plague
echinococcosis
Lassa fever
listeriosis
Lyme disease
monkeypox
psittacosis
rabies
salmonellosis
trichinosis
toxoplasmosis
typhus and
West Nile fever
Zoonoses may appear suddenly and be relatively virulent, as illustrated by HIV which ignited the AIDS epidemic and the coronavirus responsible for the outbreak of SARS.
Some examples include:
anthrax
ascariasis
brucellosis
plague
echinococcosis
Lassa fever
listeriosis
Lyme disease
monkeypox
psittacosis
rabies
salmonellosis
trichinosis
toxoplasmosis
typhus and
West Nile fever
Zoonoses may appear suddenly and be relatively virulent, as illustrated by HIV which ignited the AIDS epidemic and the coronavirus responsible for the outbreak of SARS.
Zoonosis
Zoonosis: An infectious disease in animals that can be transmitted to people. The natural reservoir for the infectious agent is a animal.
Examples of zoonoses include rabies (a viral disease that can be transmitted to humans through an infected animal's bite) and psittacosis (a chlamydial infection resembling influenza that is spread to humans by the droppings of infected birds).
Anthrax is a zoonosis. It normally affects animals, especially ruminants (such as goats, cattle, sheep, and horses), but can be transmitted to humans by contact with infected animals or their products or by biological warfare.
Examples of zoonoses include rabies (a viral disease that can be transmitted to humans through an infected animal's bite) and psittacosis (a chlamydial infection resembling influenza that is spread to humans by the droppings of infected birds).
Anthrax is a zoonosis. It normally affects animals, especially ruminants (such as goats, cattle, sheep, and horses), but can be transmitted to humans by contact with infected animals or their products or by biological warfare.
Zone Diet
Zone diet: The Zone diet is a weight loss plan based upon the idea that the right ratio of carbohydrates to proteins and fats can control levels of insulin in the bloodstream. Too much of the hormone, according to the diet's developer Barry Sears, PhD, can increase fat storage and inflammation in the body.
In his book The Zone, Sears writes that metabolism can be best regulated with a diet of 40% carbohydrates, 30% protein, and 30% fat. This idea is now widely known as the 40-30-30 plan. The diet does not prohibit any foods, but severely restricts those high in fat and carbohydrates. Fruits and vegetables are the preferred source of carbohydrates in the Zone diet. Protein is limited to low-fat portions that are no bigger and no thicker than the palm of the hand. Monounsaturated fats such as olive oil, canola oil, almonds, macadamia nuts, and avocados are recommended.
The American Heart Association (AHA) classifies the Zone as a high-protein diet and has issued an official recommendation warning against such programs. The AHA statement says high-protein diets have not been proven effective for long-term weight loss and could actually be hazardous to health because they restrict intake of essential vitamins and minerals . On the other hand, the American Dietetic Association (ADA) rates The Zone more moderately and suggests that it is closer to dieticians' recommendations than some other high-protein diets.
In his book The Zone, Sears writes that metabolism can be best regulated with a diet of 40% carbohydrates, 30% protein, and 30% fat. This idea is now widely known as the 40-30-30 plan. The diet does not prohibit any foods, but severely restricts those high in fat and carbohydrates. Fruits and vegetables are the preferred source of carbohydrates in the Zone diet. Protein is limited to low-fat portions that are no bigger and no thicker than the palm of the hand. Monounsaturated fats such as olive oil, canola oil, almonds, macadamia nuts, and avocados are recommended.
The American Heart Association (AHA) classifies the Zone as a high-protein diet and has issued an official recommendation warning against such programs. The AHA statement says high-protein diets have not been proven effective for long-term weight loss and could actually be hazardous to health because they restrict intake of essential vitamins and minerals . On the other hand, the American Dietetic Association (ADA) rates The Zone more moderately and suggests that it is closer to dieticians' recommendations than some other high-protein diets.
Zona pellucida
Zona pellucida: The strong membrane that forms around an ovum as it develops in the ovary. The membrane remains in place during the egg's travels through the Fallopian tube. To fertilize the egg, a sperm must penetrate the thinning zona pellucida. If fertilization takes place, the membrane disappears to permit implantation in the uterus.
Zona
Zona: 1. A synonym for shingles. 2. Any zone or encircling area. 3. Any area with a specific boundary.
Zona, Latin for a girdle, is a synonym for shingles because it can appear to girdle part of the body.
Zona, Latin for a girdle, is a synonym for shingles because it can appear to girdle part of the body.
Zolpidem
Zolpidem: Brand name: Ambien. A sedative hypnotic drug in a class closely related the benzodiazepines, affecting the central nervous system, used as a sleep drug. For more information, see: zolpidem.
Zolmitriptan
Zolmitriptan: A triptan drug for the treatment of migraine. Marketed under the brand name Zomig
Zollinger-Ellison syndrome
Zollinger-Ellison syndrome: A rare disorder caused by a tumor called a gastrinoma, most often occurring in the pancreas. The tumor secretes the hormone gastrin, which causes increased production of gastric acid leading to severe recurrent ulcers of the esophagus, stomach, and the upper portions of the small intestine (the duodenum and jejunum).
Gastrinomas resulting in the Zollinger-Ellison syndrome are not limited to the pancreas but may also occur in the stomach, duodenum, spleen and lymph nodes.
The treatment of the Zollinger-Ellison syndrome includes the use of H2 antagonists (for example cimetidine [brand name: Tagamet] and ranitidine [Zantac]) and the proton pump inhibitors (for example, lansoprazole [Prevacid] and omeprazole [Prilosec]). The H2 antagonists block the action of histamine on stomach cells, thus reducing stomach acid production. The proton pump inhibitors also block the production of acid by the stomach cells. Surgical removal of the tumor is curative in about 25% of cases.
The syndrome is named for two American surgeons Robert M. Zollinger (1903-1992) and Edwin H. Ellison (1918-1970).
Gastrinomas resulting in the Zollinger-Ellison syndrome are not limited to the pancreas but may also occur in the stomach, duodenum, spleen and lymph nodes.
The treatment of the Zollinger-Ellison syndrome includes the use of H2 antagonists (for example cimetidine [brand name: Tagamet] and ranitidine [Zantac]) and the proton pump inhibitors (for example, lansoprazole [Prevacid] and omeprazole [Prilosec]). The H2 antagonists block the action of histamine on stomach cells, thus reducing stomach acid production. The proton pump inhibitors also block the production of acid by the stomach cells. Surgical removal of the tumor is curative in about 25% of cases.
The syndrome is named for two American surgeons Robert M. Zollinger (1903-1992) and Edwin H. Ellison (1918-1970).
Zollinger-Ellison syndrome
Zollinger-Ellison syndrome: A rare disorder caused by a tumor called a gastrinoma, most often occurring in the pancreas. The tumor secretes the hormone gastrin, which causes increased production of gastric acid leading to severe recurrent ulcers of the esophagus, stomach, and the upper portions of the small intestine (the duodenum and jejunum).
Gastrinomas resulting in the Zollinger-Ellison syndrome are not limited to the pancreas but may also occur in the stomach, duodenum, spleen and lymph nodes.
The treatment of the Zollinger-Ellison syndrome includes the use of H2 antagonists (for example cimetidine [brand name: Tagamet] and ranitidine [Zantac]) and the proton pump inhibitors (for example, lansoprazole [Prevacid] and omeprazole [Prilosec]). The H2 antagonists block the action of histamine on stomach cells, thus reducing stomach acid production. The proton pump inhibitors also block the production of acid by the stomach cells. Surgical removal of the tumor is curative in about 25% of cases.
The syndrome is named for two American surgeons Robert M. Zollinger (1903-1992) and Edwin H. Ellison (1918-1970).
Gastrinomas resulting in the Zollinger-Ellison syndrome are not limited to the pancreas but may also occur in the stomach, duodenum, spleen and lymph nodes.
The treatment of the Zollinger-Ellison syndrome includes the use of H2 antagonists (for example cimetidine [brand name: Tagamet] and ranitidine [Zantac]) and the proton pump inhibitors (for example, lansoprazole [Prevacid] and omeprazole [Prilosec]). The H2 antagonists block the action of histamine on stomach cells, thus reducing stomach acid production. The proton pump inhibitors also block the production of acid by the stomach cells. Surgical removal of the tumor is curative in about 25% of cases.
The syndrome is named for two American surgeons Robert M. Zollinger (1903-1992) and Edwin H. Ellison (1918-1970).
Zoll, Paul M.
Zoll, Paul M.: American cardiologist (1911-1999) and pioneer in the development of the cardiac monitor, pacemaker and defibrillator.
Zinc ointment
Zinc ointment: A topical preparation containing zinc that is applied to protect the skin from irritation or sunburn. Zinc ointment is often the basis for commercial preparations for preventing diaper rash. It should not be used on skin that is already broken or irritated, however.
ZNF9
ZNF9: A gene that encodes a protein called zinc finger protein 9. An inherited mutation in ZNF9 causes type 2 myotonic dystrophy. One region of the ZNF9 gene has a particular 4-base-pair sequence, CCTG, that is normally repeated a few times. (Base pairs are the building blocks of DNA.) This region is called a tetranucleotide repeat. The inherited mutation in the ZNF9 gene that causes type 2 myotonic dystrophy is an abnormally large segment made up of the four repeated DNA base pairs (CCTG). This expanded tetranucleotide repeat is copied from 75 to more than 11,000 times in people who have the disease, with an average of about 5,000 repeats.
Messenger RNA from the altered ZNF9 gene can interact with certain proteins to form clumps in the nucleus of the cell. The altered messenger RNA is thought to disrupt the ability to make the ZNF9 protein and the proteins of other genes. This disruption prevents cells from functioning normally, leading to the signs and symptoms of type 2 myotonic dystrophy.
The protein made by ZNF9 has seven areas, called zinc finger domains, which are thought to bind to specific sites on messenger RNA (a molecule similar to DNA that carries information for making proteins). Zinc finger protein 9 plays a role in regulating genes involved in the production and use of cholesterol. The protein is found in many of the body's tissues, but is most abundant in heart and skeletal muscle.
Messenger RNA from the altered ZNF9 gene can interact with certain proteins to form clumps in the nucleus of the cell. The altered messenger RNA is thought to disrupt the ability to make the ZNF9 protein and the proteins of other genes. This disruption prevents cells from functioning normally, leading to the signs and symptoms of type 2 myotonic dystrophy.
The protein made by ZNF9 has seven areas, called zinc finger domains, which are thought to bind to specific sites on messenger RNA (a molecule similar to DNA that carries information for making proteins). Zinc finger protein 9 plays a role in regulating genes involved in the production and use of cholesterol. The protein is found in many of the body's tissues, but is most abundant in heart and skeletal muscle.
ZIP code, protein
ZIP code, protein: An informal name for a molecular cell biology system of signals or "address tags" that guide the movement of a protein within a cell. In more technical terms, protein ZIP codes* are molecular signals that direct the protein from the endoplasmic reticulum, where it is assembled, to the cytoplasm of the cell and into other cellular compartments such as the nucleus of the cell.
Mutations in this molecular system of protein "ZIP codes" have been found to cause several human genetic (hereditary) disorders, including cystic fibrosis and hyperoxaluria (a disorder that causes a special type of stone to form in the urine beginning in childhood).
In 1999 Dr. Gunter Blobel of the Rockefeller University in New York received the Nobel Laureate in Medicine or Physiology for his discovery of this protein signal system of "ZIP codes."
* For the benefit of viewers not familiar with the United States mail system, the term "ZIP code" refers to address codes of the U.S. Postal Service used to sort mail into geographic regions.
Mutations in this molecular system of protein "ZIP codes" have been found to cause several human genetic (hereditary) disorders, including cystic fibrosis and hyperoxaluria (a disorder that causes a special type of stone to form in the urine beginning in childhood).
In 1999 Dr. Gunter Blobel of the Rockefeller University in New York received the Nobel Laureate in Medicine or Physiology for his discovery of this protein signal system of "ZIP codes."
* For the benefit of viewers not familiar with the United States mail system, the term "ZIP code" refers to address codes of the U.S. Postal Service used to sort mail into geographic regions.
Zinsser disease
Zinsser disease: Also called Brill-Zinsser disease, recrudescence of epidemic typhus years after the initial attack. The agent that causes epidemic typhus (Rickettsia prowazekii) remains viable for many years and then when host defenses are down, it is reactivated causing recurrent typhus. The disease is named for the physician Nathan Brill and the great bacteriologist Hans Zinsser.
Zinc sulfate
Zinc sulfate: A form of zinc that can be administered in eye drops. It is used in some types of eye tests.
Zinc ointment
Zinc ointment: A topical preparation containing zinc that is applied to protect the skin from irritation or sunburn. Zinc ointment is often the basis for commercial preparations for preventing diaper rash. It should not be used on skin that is already broken or irritated, however.
Zinc finger
Zinc finger: A finger-shaped fold in a protein that permits it to interact with DNA and RNA. The fold is created by the binding of specific amino acids in the protein to a zinc atom. Zinc-finger proteins regulate the expression of genes as well as nucleic acid recognition, reverse transcription and virus assembly.
Zinc excess
Zinc excess: Too much zinc can cause gastrointestinal irritation (upset stomach), interfere with copper absorption and cause copper deficiency, and (like too little zinc) cause immune deficiency. According to the National Academy of Sciences, the Recommended Dietary Allowances of zinc are 12 milligrams per day for women and 10 milligrams per day for men.
Zinc deficiency dermatitis and diarrhea
Zinc deficiency dermatitis and diarrhea: Among the consequences of zinc deficiency, dermatitis (skin inflammation) and diarrhea are particularly prominent features.
A genetic disease called acrodermatitis enteropathica in which there is impaired zinc uptake from the intestine is, in fact, characterized by the simultaneous presence of dermatitis (skin inflammation) and diarrhea. The skin on the cheeks, elbows and knees and the tissues about the mouth and anus are inflamed. There is balding of the scalp, eyebrows and eyelashes. Wound healing is delayed. And there are recurrent bacterial and fungal infections due to immune deficiency. The key laboratory finding in acrodermatitis enteropathica is an abnormally low blood zinc level reflecting the impaired zinc uptake. Treatment with zinc is curative.
A genetic disease called acrodermatitis enteropathica in which there is impaired zinc uptake from the intestine is, in fact, characterized by the simultaneous presence of dermatitis (skin inflammation) and diarrhea. The skin on the cheeks, elbows and knees and the tissues about the mouth and anus are inflamed. There is balding of the scalp, eyebrows and eyelashes. Wound healing is delayed. And there are recurrent bacterial and fungal infections due to immune deficiency. The key laboratory finding in acrodermatitis enteropathica is an abnormally low blood zinc level reflecting the impaired zinc uptake. Treatment with zinc is curative.
Zinc deficiency
Zinc deficiency: Lack of zinc in the body.
According to the National Academy of Sciences, the Recommended Dietary Allowances of zinc are 12 milligrams per day for women and 10 milligrams per day for men. Food sources of zinc include meat including liver, eggs, seafood, nuts and cereal.
Deficiency of zinc is associated with short stature, anemia, increased pigmentation of skin (hyperpigmentation), enlarged liver and spleen (hepatosplenomegaly), impaired gonadal function (hypogonadism), impaired wound healing, and immune deficiency.
In a genetic disease called acrodermatitis enteropathica, there is impaired zinc uptake from the intestine. The condition is characterized by the simultaneous presence of dermatitis (skin inflammation) and diarrhea. The skin on the cheeks, elbows and knees and the tissues about the mouth and anus are inflamed. There is balding of the scalp, eyebrows and eyelashes. Wound healing is delayed. And there are recurrent bacterial and fungal infections due to immune deficiency. The key laboratory finding is an abnormally low blood zinc level reflecting the impaired zinc uptake. Treatment with zinc is curative.
According to the National Academy of Sciences, the Recommended Dietary Allowances of zinc are 12 milligrams per day for women and 10 milligrams per day for men. Food sources of zinc include meat including liver, eggs, seafood, nuts and cereal.
Deficiency of zinc is associated with short stature, anemia, increased pigmentation of skin (hyperpigmentation), enlarged liver and spleen (hepatosplenomegaly), impaired gonadal function (hypogonadism), impaired wound healing, and immune deficiency.
In a genetic disease called acrodermatitis enteropathica, there is impaired zinc uptake from the intestine. The condition is characterized by the simultaneous presence of dermatitis (skin inflammation) and diarrhea. The skin on the cheeks, elbows and knees and the tissues about the mouth and anus are inflamed. There is balding of the scalp, eyebrows and eyelashes. Wound healing is delayed. And there are recurrent bacterial and fungal infections due to immune deficiency. The key laboratory finding is an abnormally low blood zinc level reflecting the impaired zinc uptake. Treatment with zinc is curative.
Zinc
Zinc: A mineral essential to the body, zinc is a constituent of many enzymes that permit chemical reactions to proceed at normal rates. It is involved in the manufacture of protein (protein synthesis) and in cell division. Zinc is also a constituent of insulin, and is concerned with the sense of smell.
Food sources of zinc include meat, particularly liver and seafood; eggs; nuts; and cereal grains.
Deficiency of zinc is associated with short stature, anemia, increased pigmentation of skin (hyperpigmentation), enlarged liver and spleen (hepatosplenomegaly), impaired gonadal function (hypogonadism), impaired wound healing, and immune deficiency. (For a genetic disorder that impairs zinc uptake, please see Acrodermatitis enteropathica).
Too much zinc can cause gastrointestinal irritation (upset stomach), interfere with copper absorption and cause copper deficiency, and (like too little zinc) cause immune deficiency.
According to the National Academy of Sciences, the Recommended Dietary Allowance of zinc is 12 milligrams per day for women and 10 milligrams per day for men.
Food sources of zinc include meat, particularly liver and seafood; eggs; nuts; and cereal grains.
Deficiency of zinc is associated with short stature, anemia, increased pigmentation of skin (hyperpigmentation), enlarged liver and spleen (hepatosplenomegaly), impaired gonadal function (hypogonadism), impaired wound healing, and immune deficiency. (For a genetic disorder that impairs zinc uptake, please see Acrodermatitis enteropathica).
Too much zinc can cause gastrointestinal irritation (upset stomach), interfere with copper absorption and cause copper deficiency, and (like too little zinc) cause immune deficiency.
According to the National Academy of Sciences, the Recommended Dietary Allowance of zinc is 12 milligrams per day for women and 10 milligrams per day for men.
ZIFT
ZIFT: Stands for zygote intrafallopian transfer, a method used to treat infertility in which an egg fertilized in vitro (outside the body) is placed into a woman's fallopian tube. This technique is one used to overcome infertility, the inability of couples to produce offspring on their own.
The egg and the male sperm needed to fertilize it are harvested. Then the egg and the sperm are united in a petri dish, a multi- purpose glass or plastic container with a lid. If all goes well, the sperm fertilizes the egg, and the physicians then implant it in a fallopian tube. From there, nature takes its course, and the egg eventually is deposited by the fallopian tube into the uterus (womb) for development.
A zygote is the combined cell resulting from the union of sperm and egg. A zygote develops into an embryo. An embryo, a mass of cells with no recognizable human features, begins formation of a human body. After about seven or eight weeks, the embryo exhibits recognizable features such as a mouth and ears. At this stage, the developing human becomes known as a fetus. The word "zygote" is derived from the Greek word "zygon" (yoke).
The term "intrafallopian" means "inside the fallopian tubes." ("Intra," a Latin word, means "within" or "inside.") Thus, the term "zygote intrafallopian transfer" refers to the transfer of a zygote into a fallopian tube.
The egg and the male sperm needed to fertilize it are harvested. Then the egg and the sperm are united in a petri dish, a multi- purpose glass or plastic container with a lid. If all goes well, the sperm fertilizes the egg, and the physicians then implant it in a fallopian tube. From there, nature takes its course, and the egg eventually is deposited by the fallopian tube into the uterus (womb) for development.
A zygote is the combined cell resulting from the union of sperm and egg. A zygote develops into an embryo. An embryo, a mass of cells with no recognizable human features, begins formation of a human body. After about seven or eight weeks, the embryo exhibits recognizable features such as a mouth and ears. At this stage, the developing human becomes known as a fetus. The word "zygote" is derived from the Greek word "zygon" (yoke).
The term "intrafallopian" means "inside the fallopian tubes." ("Intra," a Latin word, means "within" or "inside.") Thus, the term "zygote intrafallopian transfer" refers to the transfer of a zygote into a fallopian tube.
Zidovudine triphosphate
Zidovudine triphosphate: The active form of zidovudine which is also known as AZT. See: AZT.
Zhitai
Zhitai: One of the three major preparations of red yeast rice, a tradition Chinese medicine now used to lower cholesterol.
Zenker diverticulum
Zenker diverticulum: The most common type of outpouching in the esophagus, due to increased pressure causing the mucous membrane of the esophagus to herniate through a defect in the wall of esophagus. Zenker diverticuli are usually located in the posterior hypopharyngeal wall. Small Zenker diverticuli may not cause symptoms but larger ones may collect food and obstruct the esophagus.
Named for the German physician and pathologist Friedrich Albert von Zenker (1825-1898). Also called hypopharyngeal diverticulum and pharyngoesophageal diverticulum.
Named for the German physician and pathologist Friedrich Albert von Zenker (1825-1898). Also called hypopharyngeal diverticulum and pharyngoesophageal diverticulum.
Zellweger syndrome
Zellweger syndrome: A genetic disorder, also called the cerebrohepatorenal syndrome, characterized by the reduction or absence of peroxisomes (cell structures that rid the body of toxic substances) in the cells of the liver, kidneys, and brain. Zellweger syndrome is one of a group of disorders called the leukodystrophies, all of which affect the myelin sheath, the fatty covering which acts as an insulator on nerve fibers in the brain.
The most common features of Zellweger syndrome include an enlarged liver, high levels of iron and copper in the blood, and vision disturbances. Some affected infants may show prenatal growth failure. Symptoms at birth may include lack of muscle tone and an inability to move. Other symptoms may include unusual facial characteristics, mental retardation, seizures, and an inability to suck and/or swallow. Jaundice and gastrointestinal bleeding may also occur.
There is no cure for Zellweger syndrome and there is no standard course of treatment. Infections are guarded against to prevent such complications as pneumonia and respiratory distress. Other treatment is symptomatic and supportive.
The prognosis (outlook) with Zellweger syndrome is poor. Death usually occurs within 6 months after onset, and may be caused by respiratory distress, gastrointestinal bleeding, or liver failure.
The syndrome is caused by mutations (changes) in any of several different genes involved in peroxisome formation. These genes lie on at least two different chromosome locations including chromosome 2 (region 2p15) and chromosome 7 (region 7q21-q22).
The syndrome is named for the Swiss-born pediatrician Hans Zellweger (1909-1990) who came to the US and for many years was at the University of Iowa.
The most common features of Zellweger syndrome include an enlarged liver, high levels of iron and copper in the blood, and vision disturbances. Some affected infants may show prenatal growth failure. Symptoms at birth may include lack of muscle tone and an inability to move. Other symptoms may include unusual facial characteristics, mental retardation, seizures, and an inability to suck and/or swallow. Jaundice and gastrointestinal bleeding may also occur.
There is no cure for Zellweger syndrome and there is no standard course of treatment. Infections are guarded against to prevent such complications as pneumonia and respiratory distress. Other treatment is symptomatic and supportive.
The prognosis (outlook) with Zellweger syndrome is poor. Death usually occurs within 6 months after onset, and may be caused by respiratory distress, gastrointestinal bleeding, or liver failure.
The syndrome is caused by mutations (changes) in any of several different genes involved in peroxisome formation. These genes lie on at least two different chromosome locations including chromosome 2 (region 2p15) and chromosome 7 (region 7q21-q22).
The syndrome is named for the Swiss-born pediatrician Hans Zellweger (1909-1990) who came to the US and for many years was at the University of Iowa.
Zeitgeber
Zeitgeber: An environmental agent or event that provides the cue for setting or resetting a biological clock. To be synchronized with our environment, we need the input of Zeitgebers. The most important Zeitgeber in nature is light. Social factors, chemical factors and activity can also serve as Zeitgebers. Light is a so-called photic type Zeitgeber, whereas activity, for example, is called a non-photic Zeitgeber for the biological clock.
Zeitgeber comes from the German Zeit, time + Geber, giver = time-giver. The term Zeitgeber was introduced into science about 1954 by Jurgen Aschoff, then the Director of the Max-Planck-Institute in Erling-Andechs, near Munich.
Zeitgeber comes from the German Zeit, time + Geber, giver = time-giver. The term Zeitgeber was introduced into science about 1954 by Jurgen Aschoff, then the Director of the Max-Planck-Institute in Erling-Andechs, near Munich.
Zebra
Zebra: The term "zebra" in medicine does not refer to the striped African animal but to an unlikely diagnostic possibility. It comes from an old saying in teaching medical students about how to think logically in regard to the differential diagnosis: "When you hear hoof beats, think of horses, not zebras."
For example, when someone develops a mild transient cough, tuberculosis is a "zebra." For another example, following the discovery of West Nile fever in New York City in September, 1999, the Centers for Disease Control and Prevention warned doctors to expect more infectious disease "zebras" (diseases due to rare microbes).
For example, when someone develops a mild transient cough, tuberculosis is a "zebra." For another example, following the discovery of West Nile fever in New York City in September, 1999, the Centers for Disease Control and Prevention warned doctors to expect more infectious disease "zebras" (diseases due to rare microbes).
ZAP-70
ZAP-70: Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell proliferative diseases and a subgroup of chronic lymphocytic leukemia (CLL). The ZAP-70 gene is in chromosome 2q12.
Zaleplon
Zaleplon: Brand name: Sonata. A sedative hypnotic drug in a class closely related the benzodiazepines, affecting the central nervous system, used as a sleep drug. For more information, see: zaleplon.
Z chromosome
Z chromosome: A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.
Yttrium Y 90 ibritumomab tiuxetan
Yttrium Y 90 ibritumomab tiuxetan: An anticancer drug that is a combination of the radioisotope yttrium-90 and a monoclonal antibody, a produced substances that can locate and bind to cancer cells. Also called IDEC-Y2B8 monoclonal antibody.
Yttrium
Yttrium: A rare elemental metal. A radioactive form of yttrium is used in radiation therapy and some types of immunotherapy.
Youth violence
Youth violence: Violence involving young persons, typically children, adolescents, and young adults between the ages of 10 and 24. The young person can be the victim, the perpetrator, or both. Youth violence includes aggressive behaviors such as verbal abuse, bullying, hitting, slapping, or fistfighting. These behaviors have significant consequences but do not generally result in serious injury or death. Youth violence also includes serious violent and delinquent acts such as aggravated assault, robbery, rape, and homicide, committed by and against youth. In addition to causing injury and death, youth violence undermines communities by increasing the cost of health care, reducing productivity, decreasing property values, and disrupting social services.
High-profile school shootings have increased public concern over student safety. The students at higher risk for a school-associated violent death include those from racial and ethnic minorities who attend urban high schools. US schools, however, offer more safety than homes or neighborhoods do. School-associated violent deaths represent less than 1% of all homicides and suicides that occur among school-aged children. Many violence prevention programs are centered in schools for practical reasons. Youth already gather there on a regular basis. Schools can implement interventions, set policies, and alter physical surroundings to minimize risk factors for violence. Thus, schools can create a model environment.
Adolescents can experience violence within the context of a dating relationship. This may occur when one person in a relationship uses abusive behaviors to demonstrate power or control over the other person. Dating violence includes physical violence, sexual assault, and verbal or emotional abuse.
High-profile school shootings have increased public concern over student safety. The students at higher risk for a school-associated violent death include those from racial and ethnic minorities who attend urban high schools. US schools, however, offer more safety than homes or neighborhoods do. School-associated violent deaths represent less than 1% of all homicides and suicides that occur among school-aged children. Many violence prevention programs are centered in schools for practical reasons. Youth already gather there on a regular basis. Schools can implement interventions, set policies, and alter physical surroundings to minimize risk factors for violence. Thus, schools can create a model environment.
Adolescents can experience violence within the context of a dating relationship. This may occur when one person in a relationship uses abusive behaviors to demonstrate power or control over the other person. Dating violence includes physical violence, sexual assault, and verbal or emotional abuse.
Youth
Youth: The time between childhood and maturity. (Unfortunately, as the songwriter Sammy Cahn noted, "youth is wasted on the young.")
Yolk sac
Yolk sac: Not all yolk has to do with birds' eggs. Human embryos have a yolk sac, too. The human yolk sac is a membrane outside the embryo that is connected by a tube (the yolk stalk) though the umbilical opening to the embryo's midgut. The yolk sac serves as an early site for the formation of blood and in time is incorporated into the primitive gut of the embryo.
Yogurt
Yogurt: A common dish made of milk curdled and fermented with a culture of Lactobacillus (the milk bacillus). The word was acquired in the 1620s from Turkey. It can be spelled myriad ways including yogurt, yoghurt, yaghourt, yooghurt, yughard, and yaourt. The most popular spellings in the Anglo-Saxon world are yogurt and yoghurt while in France one eats yaourt.
Yoga
Yoga: A way of life that includes ethical precepts, dietary prescriptions, and physical exercise. Its practitioners believe that their discipline has the capacity to alter mental and bodily responses normally thought to be far beyond a person's ability to modulate them. During the past 80 years, health professionals in India and the West have begun to investigate the therapeutic potential of yoga. To date, thousands of research studies have been undertaken and have shown that with the practice of yogic meditation a person can, indeed, learn to control such physiologic parameters as blood pressure, heart rate, respiratory function, metabolic rate, skin resistance, brain waves, body temperature, and many other bodily functions.
Yersiniosis
Yersiniosis: An infectious disease caused by a bacterium called Yersinia enterocolitica (and, less often, other forms of Yersinia). The infection can cause a variety of symptoms depending on the age of the person infected. Common symptoms in children (who most often contract the disease) are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, or spread of bacteria to the bloodstream can occur.
Yersiniosis is most often acquired by eating contaminated food, especially raw or undercooked pork products. The preparation of raw pork intestines (chitterlings) may be particularly risky. Infants can be infected if their caretakers handle raw chitterlings and then do not adequately clean their hands before handling the infant or the infant's toys, bottles, or pacifiers. Drinking contaminated unpasteurized milk or untreated water can also transmit the infection. Occasionally Y. enterocolitica infection occurs after contact with infected animals. On rare occasions, it can be transmitted as a result of the bacterium passing from the stools or soiled fingers of one person to the mouth of another person. This may happen when basic hygiene and handwashing habits are inadequate. Rarely, the organism is transmitted through contaminated blood during a transfusion.
Yersiniosis is generally diagnosed by detecting the organism in the stool. The organism can also be recovered from other sites, including the throat, lymph nodes, joint fluid, urine, bile, and blood.
Uncomplicated cases of diarrhea due to Y. enterocolitica usually resolve on their own without antibiotic treatment. However, in more severe or complicated infections, antibiotics such as aminoglycosides, doxycycline, trimethoprim-sulfamethoxazole, or fluoroquinolones may be useful.
Most infections with Y. enterocolitica are uncomplicated and resolve completely. Occasionally, some persons develop joint pain, most commonly in the knees, ankles or wrists. These joint pains usually develop about 1 month after the initial episode of diarrhea and generally resolve after 1 to 6 months. A skin rash, called "erythema nodosum," may also appear on the legs and trunk; this is more common in women. In most cases, erythema nodosum resolves spontaneously within a month.
To prevent the infection:
1.Avoid eating raw or undercooked pork.
2.Consume only pasteurized milk or milk products.
3.Wash hands with soap and water before eating and preparing food, after contact with animals, and after handling raw meat.
4.After handling raw chitterlings, clean hands and fingernails scrupulously with soap and water before touching infants or their toys, bottles, or pacifiers. Someone other than the foodhandler should care for children while chitterlings are being prepared.
5.Prevent cross-contamination in the kitchen:
Use separate cutting boards for meat and other foods.
Carefully clean all cutting boards, counter-tops, and utensils with soap and hot water after preparing raw meat.
6.Dispose of animal feces in a sanitary manner.
Yersiniosis is most often acquired by eating contaminated food, especially raw or undercooked pork products. The preparation of raw pork intestines (chitterlings) may be particularly risky. Infants can be infected if their caretakers handle raw chitterlings and then do not adequately clean their hands before handling the infant or the infant's toys, bottles, or pacifiers. Drinking contaminated unpasteurized milk or untreated water can also transmit the infection. Occasionally Y. enterocolitica infection occurs after contact with infected animals. On rare occasions, it can be transmitted as a result of the bacterium passing from the stools or soiled fingers of one person to the mouth of another person. This may happen when basic hygiene and handwashing habits are inadequate. Rarely, the organism is transmitted through contaminated blood during a transfusion.
Yersiniosis is generally diagnosed by detecting the organism in the stool. The organism can also be recovered from other sites, including the throat, lymph nodes, joint fluid, urine, bile, and blood.
Uncomplicated cases of diarrhea due to Y. enterocolitica usually resolve on their own without antibiotic treatment. However, in more severe or complicated infections, antibiotics such as aminoglycosides, doxycycline, trimethoprim-sulfamethoxazole, or fluoroquinolones may be useful.
Most infections with Y. enterocolitica are uncomplicated and resolve completely. Occasionally, some persons develop joint pain, most commonly in the knees, ankles or wrists. These joint pains usually develop about 1 month after the initial episode of diarrhea and generally resolve after 1 to 6 months. A skin rash, called "erythema nodosum," may also appear on the legs and trunk; this is more common in women. In most cases, erythema nodosum resolves spontaneously within a month.
To prevent the infection:
1.Avoid eating raw or undercooked pork.
2.Consume only pasteurized milk or milk products.
3.Wash hands with soap and water before eating and preparing food, after contact with animals, and after handling raw meat.
4.After handling raw chitterlings, clean hands and fingernails scrupulously with soap and water before touching infants or their toys, bottles, or pacifiers. Someone other than the foodhandler should care for children while chitterlings are being prepared.
5.Prevent cross-contamination in the kitchen:
Use separate cutting boards for meat and other foods.
Carefully clean all cutting boards, counter-tops, and utensils with soap and hot water after preparing raw meat.
6.Dispose of animal feces in a sanitary manner.
Yersinia pestis
Yersinia pestis: The bacteria that causes the bubonic plague which in the year 541 (as the Black Death) and later in the Middle Ages decimated Europe. The effects of the plague are described in the nursery rhyme "We all fall down."
Y. pestis mainly infects rats and other rodents which are the prime reservoir for the bacteria. Fleas are the prime vectors carrying the bacteria from one species to another. They bite rodents infected with Y. pestis, then they bite people and so transmit the disease to them.
Transmission of the plague to people can also occur from eating infected animals such as squirrels. Once someone has the plague, they can transmit it to another person via aerosol droplets.
Plague occurs in the U.S. It is treatable with antibiotics but, if not treated promptly, can promptly lead to death.
Yersinia is named after the Swiss bacteriologist Alexandre-Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. The bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako.
Y. pestis mainly infects rats and other rodents which are the prime reservoir for the bacteria. Fleas are the prime vectors carrying the bacteria from one species to another. They bite rodents infected with Y. pestis, then they bite people and so transmit the disease to them.
Transmission of the plague to people can also occur from eating infected animals such as squirrels. Once someone has the plague, they can transmit it to another person via aerosol droplets.
Plague occurs in the U.S. It is treatable with antibiotics but, if not treated promptly, can promptly lead to death.
Yersinia is named after the Swiss bacteriologist Alexandre-Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. The bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako.
Yersinia enterocolitica
Yersinia enterocolitica: A bacterium that causes an infectious disease called yersiniosis. Yersinia enterocolitica is a member of the Yersinia family of bacteria.
Common symptoms of yersiniosis in children (who most often contract the disease) are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, or spread of bacteria to the bloodstream can occur.
Yersiniosis is most often acquired by eating contaminated food, especially raw or undercooked pork products. The preparation of raw pork intestines (chitterlings) may be particularly risky. Infants can be infected if their caretakers handle raw chitterlings and then do not adequately clean their hands before handling the infant or the infant's toys, bottles, or pacifiers. Drinking contaminated unpasteurized milk or untreated water can also transmit the infection. Occasionally Y. enterocolitica infection occurs after contact with infected animals. On rare occasions, it can be transmitted as a result of the bacterium passing from the stools or soiled fingers of one person to the mouth of another person. This may happen when basic hygiene and handwashing habits are inadequate. Rarely, the organism is transmitted through contaminated blood during a transfusion.
Yersiniosis is generally diagnosed by detecting the organism in the stool. The organism can also be recovered from other sites, including the throat, lymph nodes, joint fluid, urine, bile, and blood.
Uncomplicated cases of diarrhea due to Y. enterocolitica usually resolve on their own without antibiotic treatment. However, in more severe or complicated infections, antibiotics such as aminoglycosides, doxycycline, trimethoprim-sulfamethoxazole, or fluoroquinolones may be useful.
Most infections with Y. enterocolitica are uncomplicated and resolve completely. Occasionally, some persons develop joint pain, most commonly in the knees, ankles or wrists. These joint pains usually develop about 1 month after the initial episode of diarrhea and generally resolve after 1 to 6 months. A skin rash, called "erythema nodosum," may also appear on the legs and trunk; this is more common in women. In most cases, erythema nodosum resolves spontaneously within a month.
To prevent the infection:
1.Avoid eating raw or undercooked pork.
2.Consume only pasteurized milk or milk products.
3.Wash hands with soap and water before eating and preparing food, after contact with animals, and after handling raw meat.
4.After handling raw chitterlings, clean hands and fingernails scrupulously with soap and water before touching infants or their toys, bottles, or pacifiers. Someone other than the foodhandler should care for children while chitterlings are being prepared.
5.Prevent cross-contamination in the kitchen:
Use separate cutting boards for meat and other foods.
Carefully clean all cutting boards, counter-tops, and utensils with soap and hot water after preparing raw meat.
6.Dispose of animal feces in a sanitary manner.
Common symptoms of yersiniosis in children (who most often contract the disease) are fever, abdominal pain, and diarrhea, which is often bloody. Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, or spread of bacteria to the bloodstream can occur.
Yersiniosis is most often acquired by eating contaminated food, especially raw or undercooked pork products. The preparation of raw pork intestines (chitterlings) may be particularly risky. Infants can be infected if their caretakers handle raw chitterlings and then do not adequately clean their hands before handling the infant or the infant's toys, bottles, or pacifiers. Drinking contaminated unpasteurized milk or untreated water can also transmit the infection. Occasionally Y. enterocolitica infection occurs after contact with infected animals. On rare occasions, it can be transmitted as a result of the bacterium passing from the stools or soiled fingers of one person to the mouth of another person. This may happen when basic hygiene and handwashing habits are inadequate. Rarely, the organism is transmitted through contaminated blood during a transfusion.
Yersiniosis is generally diagnosed by detecting the organism in the stool. The organism can also be recovered from other sites, including the throat, lymph nodes, joint fluid, urine, bile, and blood.
Uncomplicated cases of diarrhea due to Y. enterocolitica usually resolve on their own without antibiotic treatment. However, in more severe or complicated infections, antibiotics such as aminoglycosides, doxycycline, trimethoprim-sulfamethoxazole, or fluoroquinolones may be useful.
Most infections with Y. enterocolitica are uncomplicated and resolve completely. Occasionally, some persons develop joint pain, most commonly in the knees, ankles or wrists. These joint pains usually develop about 1 month after the initial episode of diarrhea and generally resolve after 1 to 6 months. A skin rash, called "erythema nodosum," may also appear on the legs and trunk; this is more common in women. In most cases, erythema nodosum resolves spontaneously within a month.
To prevent the infection:
1.Avoid eating raw or undercooked pork.
2.Consume only pasteurized milk or milk products.
3.Wash hands with soap and water before eating and preparing food, after contact with animals, and after handling raw meat.
4.After handling raw chitterlings, clean hands and fingernails scrupulously with soap and water before touching infants or their toys, bottles, or pacifiers. Someone other than the foodhandler should care for children while chitterlings are being prepared.
5.Prevent cross-contamination in the kitchen:
Use separate cutting boards for meat and other foods.
Carefully clean all cutting boards, counter-tops, and utensils with soap and hot water after preparing raw meat.
6.Dispose of animal feces in a sanitary manner.
Yersinia
Yersinia: A group of bacteria that appear rod-like under the microscope and include Yersinia pestis (the cause of the bubonic and pneumonic plague), Yersinia entercolitica (the cause of a disease called yersinosis), and Yersinia pseudotuberculosis (which causes a condition called mesenteric adenitis, particularly in immunocompromised patients). Both Y. entercolitica and Y. pseudotuberculosis have also been implicated in a viral form of arthritis. Infection with Yersinia bacteria can be treated with antibiotics.
Yersinia is named after the Swiss bacteriologist Alexandre-Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. Since the bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako, Yersinia could well have been named after him.
Yersinia is named after the Swiss bacteriologist Alexandre-Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. Since the bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako, Yersinia could well have been named after him.
Yerba mate
Yerba mate: A stimulant beverage similar to tea, very popular in South America, brewed from the dried leaves and stemlets of a member of the holly family known botanically as Ilex paraguayensis.
Despite claims to the contrary, Yerba mate does contain caffeine although the level is relatively low compared to coffee or tea. Yerba mate also contains significant amounts of vitamins and minerals and other chemicals of note such as theobromine and theophylline.
Yerba mate (pronounced yer ba ma tA) comes from the American Spanish, from yerba meaning herb + mate, the hollow gourd used as a bowl or container for brewing yerba mate.
Despite claims to the contrary, Yerba mate does contain caffeine although the level is relatively low compared to coffee or tea. Yerba mate also contains significant amounts of vitamins and minerals and other chemicals of note such as theobromine and theophylline.
Yerba mate (pronounced yer ba ma tA) comes from the American Spanish, from yerba meaning herb + mate, the hollow gourd used as a bowl or container for brewing yerba mate.
Yellow jacket sting
Yellow jacket sting: A sting from a yellow jacket (or other large stinging insects such as bees, hornets and wasps) can trigger allergic reactions ranging from local responses of limited duration to catastrophic general reactions which can be fatal. The susceptibility to severe reactions appears inherited. Avoidance and prompt treatment are essential. Immediate treatment is with adrenaline by injection. In selected cases, allergy injection therapy is highly effective in desensitizing the patient. The three A's of large stinging insect allergy are Adrenaline, Avoidance and Allergist.
Yellow jack
Yellow jack: 1) The flag displayed from lazarettos, naval hospitals, and vessels in quarantine. 2) Synonym for yellow fever as, for example, in "...Fernando passed a few weeks recovering from a touch of yellow jack."
Yellow fever vaccination
Yellow fever vaccination: A live attenuated (weakened) viral vaccine that is recommended for people traveling to or living in tropical areas in the Americas and Africa where yellow fever occurs. Because it is a live vaccine, it should not be given to infants or people with immune-system problems.
Yellow fever is an acute systemic (bodywide) illness caused by a virus called a Flavivirus. In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin (provides the "yellow" in "yellow fever").
The virus of yellow fever is transmitted in most cases by a bite of the Aëdes aegypti mosquito. (In a very few cases, the virus may be transmitted by a monkey bite.) Yellow fever once ravaged port cities in the United States, but no more. Today it is most common and concentrated in tropical areas of Africa and the Americas.
There is no cure for yellow fever. Prevention of the disease with the vaccine is most important. The vaccine is based upon classic medical research done under Dr. Walter Reed. When yellow fever broke out among U.S. troops in Cuba in 1900, Dr. Reed, a member of the Army Medical Corps, headed a commission of physicians on yellow fever. They discovered that the fever was transmitted by the Aëdes aegypti mosquito which breeds near houses (and also transmit dengue). Reed's team later showed that the mosquito injected a virus that caused the dread disease. Sanitary engineers eradicated the mosquito and freed Cuba of yellow fever in 1902 (the year of Reed's death from appendicitis).
The vaccine against yellow fever is also based on the work of Max Theiler. Dr. Theiler, from South Africa, worked at the Rockefeller Foundation (now the Rockefeller University) in New York. In 1929 Theiler contracted yellow fever (not an uncommon experience among those studying the disease) but recovered and became immune to it. The following year Theiler discovered that yellow fever can be transmitted to white mice, which are easy to handle and are available by the thousand at small cost. This was a critical finding for the production of the vaccine. In 1951, Max Theiler (1899-1972) was awarded the Nobel Prize in Physiology or Medicine "for his discoveries concerning yellow fever and how to combat it."
Yellow fever is an acute systemic (bodywide) illness caused by a virus called a Flavivirus. In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin (provides the "yellow" in "yellow fever").
The virus of yellow fever is transmitted in most cases by a bite of the Aëdes aegypti mosquito. (In a very few cases, the virus may be transmitted by a monkey bite.) Yellow fever once ravaged port cities in the United States, but no more. Today it is most common and concentrated in tropical areas of Africa and the Americas.
There is no cure for yellow fever. Prevention of the disease with the vaccine is most important. The vaccine is based upon classic medical research done under Dr. Walter Reed. When yellow fever broke out among U.S. troops in Cuba in 1900, Dr. Reed, a member of the Army Medical Corps, headed a commission of physicians on yellow fever. They discovered that the fever was transmitted by the Aëdes aegypti mosquito which breeds near houses (and also transmit dengue). Reed's team later showed that the mosquito injected a virus that caused the dread disease. Sanitary engineers eradicated the mosquito and freed Cuba of yellow fever in 1902 (the year of Reed's death from appendicitis).
The vaccine against yellow fever is also based on the work of Max Theiler. Dr. Theiler, from South Africa, worked at the Rockefeller Foundation (now the Rockefeller University) in New York. In 1929 Theiler contracted yellow fever (not an uncommon experience among those studying the disease) but recovered and became immune to it. The following year Theiler discovered that yellow fever can be transmitted to white mice, which are easy to handle and are available by the thousand at small cost. This was a critical finding for the production of the vaccine. In 1951, Max Theiler (1899-1972) was awarded the Nobel Prize in Physiology or Medicine "for his discoveries concerning yellow fever and how to combat it."
Yellow fever
Yellow fever: An acute systemic (bodywide) illness caused by a virus called a Flavivirus. In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin. Hence, the "yellow" in "yellow fever."
Yellow fever once ravaged port cities in the United States. (A viewer writes in: "This disease was prevalent in the deep south, not just in the seaports. My grandparents lived through an epidemic of yellow jack in central Mississippi around 1900, and they were a long way from the seacoast.")
Today yellow fever is most common in tropical areas of Africa and the Americas. The virus of yellow fever is transmitted in most cases by a bite of a mosquito. In urban settings, yellow fever may be transmitted from person to person by the Aedes aegypti mosquito. In the jungle, yellow fever is transmitted from monkeys to people by mosquitoes that breed in tree-holes in the rainforests. The diagnosis of yellow fever is made by observation or, if need be, by culturing the virus from a blood sample.
There is no cure for yellow fever, although antiviral medications may be tried. Non-aspirin pain relievers, rest, and rehydration with fluids decrease discomfort. The disease usually passes within a few weeks.
Yellow fever can be prevented by vaccination. The yellow fever vaccine is a live attenuated (weakened) viral vaccine. It is recommended for people traveling to or living in tropical areas in the Americas and Africa where yellow fever occurs. Because it is a live vaccine, it should not be given to infants or people with immune-system impairment.
The vaccine is based upon classic medical research done under Dr. Walter Reed. When yellow fever broke out among U.S. troops in Cuba in 1900, Dr. Reed, a member of the Army Medical Corps, headed a commission of physicians on yellow fever. They discovered that the fever was transmitted by the Aëdes aegypti mosquito which breeds near houses (and also transmit dengue). Reed's team later showed that the mosquito injected a virus that caused the dread disease. Sanitary engineers eradicated the mosquito and freed Cuba of yellow fever in 1902 (the year of Reed's death from appendicitis).
.
The vaccine against yellow fever is also based on the work of Max Theiler. Dr. Theiler, from South Africa, worked at the Rockefeller Foundation (now the Rockefeller University) in New York. In 1929 Theiler contracted yellow fever (not an uncommon experience among those studying the disease) but recovered and became immune to it. The following year Theiler discovered that yellow fever can be transmitted to white mice, which are easy to handle and are available by the thousand at small cost. This was a critical finding for the production of the vaccine. In 1951, Max Theiler (1899-1972) was awarded the Nobel Prize in Physiology or Medicine "for his discoveries concerning yellow fever and how to combat it."
Yellow fever once ravaged port cities in the United States. (A viewer writes in: "This disease was prevalent in the deep south, not just in the seaports. My grandparents lived through an epidemic of yellow jack in central Mississippi around 1900, and they were a long way from the seacoast.")
Today yellow fever is most common in tropical areas of Africa and the Americas. The virus of yellow fever is transmitted in most cases by a bite of a mosquito. In urban settings, yellow fever may be transmitted from person to person by the Aedes aegypti mosquito. In the jungle, yellow fever is transmitted from monkeys to people by mosquitoes that breed in tree-holes in the rainforests. The diagnosis of yellow fever is made by observation or, if need be, by culturing the virus from a blood sample.
There is no cure for yellow fever, although antiviral medications may be tried. Non-aspirin pain relievers, rest, and rehydration with fluids decrease discomfort. The disease usually passes within a few weeks.
Yellow fever can be prevented by vaccination. The yellow fever vaccine is a live attenuated (weakened) viral vaccine. It is recommended for people traveling to or living in tropical areas in the Americas and Africa where yellow fever occurs. Because it is a live vaccine, it should not be given to infants or people with immune-system impairment.
The vaccine is based upon classic medical research done under Dr. Walter Reed. When yellow fever broke out among U.S. troops in Cuba in 1900, Dr. Reed, a member of the Army Medical Corps, headed a commission of physicians on yellow fever. They discovered that the fever was transmitted by the Aëdes aegypti mosquito which breeds near houses (and also transmit dengue). Reed's team later showed that the mosquito injected a virus that caused the dread disease. Sanitary engineers eradicated the mosquito and freed Cuba of yellow fever in 1902 (the year of Reed's death from appendicitis).
.
The vaccine against yellow fever is also based on the work of Max Theiler. Dr. Theiler, from South Africa, worked at the Rockefeller Foundation (now the Rockefeller University) in New York. In 1929 Theiler contracted yellow fever (not an uncommon experience among those studying the disease) but recovered and became immune to it. The following year Theiler discovered that yellow fever can be transmitted to white mice, which are easy to handle and are available by the thousand at small cost. This was a critical finding for the production of the vaccine. In 1951, Max Theiler (1899-1972) was awarded the Nobel Prize in Physiology or Medicine "for his discoveries concerning yellow fever and how to combat it."
Yellow enzymes
Yellow enzymes: A group of respiratory enzymes that catalyze reactions in the body permitting cells to respire, to breath. These biochemical reactions are termed oxidation-reduction reactions.
The first yellow enzyme was discovered by the German biochemist Otto Heinrich Warburg (1883-1970), a pioneer in research on the respiration of cells, who won the Nobel Prize in physiology or medicine in 1931 " for his discovery of the nature and mode of action of the respiratory enzyme."
All yellow enzymes are flavoproteins (from the Latin flavus, yellow).
The first yellow enzyme was discovered by the German biochemist Otto Heinrich Warburg (1883-1970), a pioneer in research on the respiration of cells, who won the Nobel Prize in physiology or medicine in 1931 " for his discovery of the nature and mode of action of the respiratory enzyme."
All yellow enzymes are flavoproteins (from the Latin flavus, yellow).
Yellow enzyme, Warburg's
Yellow enzyme, Warburg's: A key respiratory enzyme discovered by the German biochemist Otto Heinrich Warburg (1883-1970), a pioneer in research on the respiration of cells and the metabolism of tumors. Warburg's yellow enzyme is a flavoprotein that catalyzes an oxidation-reduction reaction necessary for normal breathing (respiration) of cells.
Warburg won the Nobel Prize in physiology or medicine in 1931 "for his discovery of the nature and mode of action of the respiratory enzyme."
Warburg won the Nobel Prize in physiology or medicine in 1931 "for his discovery of the nature and mode of action of the respiratory enzyme."
Yeast vulvitis
Yeast vulvitis: A yeast infection of the external genital organs of the female (the vulva). The vulva includes the labia, clitoris, and the entrance (the "vestibule") to the vagina.
Yeast vulvitis commonly goes together with yeast vaginitis, infection of the vagina by the fungus known as Candida.
The common symptoms are itching, burning, soreness, pain during intercourse and urination, and vaginal discharge.
Yeast infection occurs when new yeast are introduced into the area or there is an increase in the quantity of yeast there relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the vulva and vagina (vaginitis).
Yeast infection of the vulva and vagina tends also to occur with any injury to these tissues (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
The infection can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast vulvitis commonly goes together with yeast vaginitis, infection of the vagina by the fungus known as Candida.
The common symptoms are itching, burning, soreness, pain during intercourse and urination, and vaginal discharge.
Yeast infection occurs when new yeast are introduced into the area or there is an increase in the quantity of yeast there relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the vulva and vagina (vaginitis).
Yeast infection of the vulva and vagina tends also to occur with any injury to these tissues (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
The infection can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast vulvitis
Yeast vulvitis: A yeast infection of the external genital organs of the female (the vulva). The vulva includes the labia, clitoris, and the entrance (the "vestibule") to the vagina.
Yeast vulvitis commonly goes together with yeast vaginitis, infection of the vagina by the fungus known as Candida.
The common symptoms are itching, burning, soreness, pain during intercourse and urination, and vaginal discharge.
Yeast infection occurs when new yeast are introduced into the area or there is an increase in the quantity of yeast there relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the vulva and vagina (vaginitis).
Yeast infection of the vulva and vagina tends also to occur with any injury to these tissues (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
The infection can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast vulvitis commonly goes together with yeast vaginitis, infection of the vagina by the fungus known as Candida.
The common symptoms are itching, burning, soreness, pain during intercourse and urination, and vaginal discharge.
Yeast infection occurs when new yeast are introduced into the area or there is an increase in the quantity of yeast there relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the vulva and vagina (vaginitis).
Yeast infection of the vulva and vagina tends also to occur with any injury to these tissues (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
The infection can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast vaginitis
: Infection of the vagina by a fungus known as Candida, characteristically causing itching, burning, soreness, pain during intercourse and urination, and vaginal discharge.
Yeast vaginitis occurs when new yeast are introduced into the vagina or there is an increase in the quantity of yeast in the vagina relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the lining of the vagina (vaginitis).
Yeast vaginitis tends also to occur with any injury to the vagina (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
Yeast vaginitis can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast vaginitis occurs when new yeast are introduced into the vagina or there is an increase in the quantity of yeast in the vagina relative to the quantity of bacteria (as when bacteria are eradicated by antibiotics). The yeast can then take over and cause irritation of the lining of the vagina (vaginitis).
Yeast vaginitis tends also to occur with any injury to the vagina (as from chemotherapy), immune deficiency (as from AIDS or from using cortisone-type medications) and in women with diabetes mellitus.
Yeast vaginitis can be treated with antifungal medications applied to the affected area or taken by mouth. Topically applied antibiotic creams include butoconazole (FEMSTAT 3), clotrimazole (LOTRIMIN), miconazole (MONISTAT), and terconazole (TERAZOL 3). Clotrimazole, miconazole, terconazole, and nystatin (MYCOSTATIN) are also available as vaginal tablets. Oral antibiotics for yeast vaginitis and vulvitis include fluconazole (DIFLUCAN). During pregnancy, only the topical creams are used.
Candida may be normally present in small numbers in some women and not cause disease but the presence of Candida without symptoms of infection does not require treatment.
Yeast syndrome
Yeast syndrome: The yeast Candida has been thought to cause a syndrome with a number of nonspecific problems including fatigue, loss of appetite, headache, short-attention span, depression and all manner of intestinal irregularities. There is no scientific evidence to support the existence of the yeast syndrome (also called the yeast connection).
Yeast rash
Yeast rash: A slightly raised pink-to-red rash caused by proliferation of yeast, usually in a moist area such as the groin. It is most common in infants, but can also occur on the skin of older children and adults. Treatment is by keeping the affected area clean and dry, and applying topical antifungal medication. Also known as diaper dermatitis, nappy rash.
Yeast infection
Yeast infection: Overgrowth of yeast can affect the skin (yeast rash), mouth (thrush), digestive tract, esophagus, vagina (vaginitis), and other parts of the body. Yeast infections occur most frequently in moist areas of the body. Although Candida albicans and other Candida yeasts are the most frequent offenders, other yeast groups are known to cause illness, primarily in immunocompromised patients. These include Torulopsis, Cryptococcus, Malassezia, and Trichosporon yeasts. Diagnosis is by observation, and can be confirmed by culturing a stool or mucosa sample, or a scraping from the affected area. Treatment is by topical or oral antifungal medications. Acidophilous, a helpful bacteria that normally helps to keep yeast in check, can also be tried in supplement form or in yogurt with live cultures.
See also Candida albicans, candidiasis, thrush, yeast vaginitis, yeast rash.
See also Candida albicans, candidiasis, thrush, yeast vaginitis, yeast rash.
Yeast genome
Yeast genome: All of the genetic information contained in yeast (Saccharomyces cerevisiae).
The genomes of particular nonhuman organisms such as yeast have been studied for a number of reasons including the need to improve sequencing and analysis techniques. These nonhuman genomes also provide powerful sets of data against which to compare the human genome.
For example, a gene known to govern the rate of aging in yeast cells has been found to be active in mice, yielding a new insight into why mice and people age and, possibly, ways of enhancing life span.
The Saccharomyces cerevisiae (yeast) genome contains 12.1 million base pairs and is estimated to have 6,034 genes. The sequencing of this genome was completed in 1996.
The genomes of particular nonhuman organisms such as yeast have been studied for a number of reasons including the need to improve sequencing and analysis techniques. These nonhuman genomes also provide powerful sets of data against which to compare the human genome.
For example, a gene known to govern the rate of aging in yeast cells has been found to be active in mice, yielding a new insight into why mice and people age and, possibly, ways of enhancing life span.
The Saccharomyces cerevisiae (yeast) genome contains 12.1 million base pairs and is estimated to have 6,034 genes. The sequencing of this genome was completed in 1996.
Yeast diaper rash
Yeast diaper rash: Infection in the diaper area caused by a yeast formerly called Monilia and now called Candida. These organisms are part of the germs normally found in various parts of the body and ordinarily do not cause any symptoms.
Certain conditions, such as antibiotic use or excessive moisture, may upset the balance of microbes and allow an overgrowth of Candida. Candida may exacerbate diaper rash and make it much worse, as this yeast grows very readily on damaged skin. The infected skin is usually fiery red with areas that may have a raised red border.
Certain conditions, such as antibiotic use or excessive moisture, may upset the balance of microbes and allow an overgrowth of Candida. Candida may exacerbate diaper rash and make it much worse, as this yeast grows very readily on damaged skin. The infected skin is usually fiery red with areas that may have a raised red border.
Yeast artificial chromosome (YAC)
Yeast artificial chromosome (YAC): A vector (carrier) created and used in the laboratory to clone pieces of DNA.
A YAC is constructed from the telomeric, centromeric, and replication origin sequences needed for replication in yeast cells. (The telomere is the end of the chromosome; the centromere is the chromosome region to which spindle fibers attach during cell division; and the replication origin sequences are the spots where the replication of DNA starts.)
A YAC is constructed from the telomeric, centromeric, and replication origin sequences needed for replication in yeast cells. (The telomere is the end of the chromosome; the centromere is the chromosome region to which spindle fibers attach during cell division; and the replication origin sequences are the spots where the replication of DNA starts.)
Yeast
Yeast: A group of single-celled fungi that reproduce by budding.
Most yeast are harmless (some are used in baking and brewing). Yeast is commonly present on normal human skin and in areas of moisture, such as the mouth and vagina, usually without causing any problems.
However, yeast can produce disease in people. For example, the yeast Candida (once called Monilia) causes thrush (oral infection) and diaper rash in infants, fingernail infections, vaginal area infections in women after puberty, and a host of problems in patients with immune deficiency.
Most yeast are harmless (some are used in baking and brewing). Yeast is commonly present on normal human skin and in areas of moisture, such as the mouth and vagina, usually without causing any problems.
However, yeast can produce disease in people. For example, the yeast Candida (once called Monilia) causes thrush (oral infection) and diaper rash in infants, fingernail infections, vaginal area infections in women after puberty, and a host of problems in patients with immune deficiency.
yd.
yd.: Abbreviation for a yard as a measure of length. A yard equals 3 feet or 36 inches. The metric equivalents for these measures of length are:
A yard = 0.9144 meter.
A foot = 30.48 centimeters.
An inch = 2.54 centimeters.
A yard = 0.9144 meter.
A foot = 30.48 centimeters.
An inch = 2.54 centimeters.
Yaws
Yaws: A common chronic infectious disease that occurs mainly in the warm humid regions of the tropics with characteristic bumps on the skin of the face, hands, feet and genital area. Almost all cases of yaws are in children under 15 years of age.
The organism that causes yaws is a spirochete. It is spiral shaped, as are all spirochetes, and is termed Treponema pertenue. (A different type of spirochete, Treponema pallidum, is the organism responsible for syphilis).
Yaws begins when the spirochete enters the skin at a spot where it was scraped, cut or otherwise compromised. At that site a painless bump arises and grows. It is the mother yaw. The glands in that area are often swollen (regional lymphadenopathy). The mother yaw heals, leaving a light-colored scar.
The mother yaw is followed by recurring ("secondary") crops of bumps and more swollen glands. These bumps may be painless like the mother yaw or they may be filled with pus, burst and ulcerate.
In its late ("tertiary") stage, yaws can destroy areas of the skin and bones and joints and deform them. The palms and soles tend to become thickened and painful ("dry crab yaws").
The diagnosis of yaws comes to the fore in any child who has the characteristic clinical features and lives in an area where the disease is common. With increasing travel, a child once in the tropics may carry the disease to a more temperate clime. Confirmation of the diagnosis is by blood tests and by special (dark- field) examination under the microscope (to see the spirochete).
Treatment of yaws is simple and highly effective. A single shot of penicillin cures the disease. Anyone allergic to penicillin can be treated with another antibiotic, usually erythromycin or tetracycline.
Yaws is a major public health problem in the tropics. Tropical regions in Central and South America, Africa, Asia, and Polynesia are at risk for yaws. A high percentage of children can be infected. Transmission of the disease is facilitated by overcrowding and poor hygiene, in the favellas of the cities of northeastern Brazil.
Yaws can be completely eradicated from an area by giving penicillin or another appropriate antibiotic to everyone in the population. This may, unfortunately, cost more than a poor country can afford.
The term "yaws" is of Caribbean origin. Because the bumps of yaws look like little berries, the disease is also called frambesia (or frambesia tropica) from the French "framboise" meaning "raspberry." Other names include granuloma tropicum polypapilloma tropicum, and thymiosis.
The organism that causes yaws is a spirochete. It is spiral shaped, as are all spirochetes, and is termed Treponema pertenue. (A different type of spirochete, Treponema pallidum, is the organism responsible for syphilis).
Yaws begins when the spirochete enters the skin at a spot where it was scraped, cut or otherwise compromised. At that site a painless bump arises and grows. It is the mother yaw. The glands in that area are often swollen (regional lymphadenopathy). The mother yaw heals, leaving a light-colored scar.
The mother yaw is followed by recurring ("secondary") crops of bumps and more swollen glands. These bumps may be painless like the mother yaw or they may be filled with pus, burst and ulcerate.
In its late ("tertiary") stage, yaws can destroy areas of the skin and bones and joints and deform them. The palms and soles tend to become thickened and painful ("dry crab yaws").
The diagnosis of yaws comes to the fore in any child who has the characteristic clinical features and lives in an area where the disease is common. With increasing travel, a child once in the tropics may carry the disease to a more temperate clime. Confirmation of the diagnosis is by blood tests and by special (dark- field) examination under the microscope (to see the spirochete).
Treatment of yaws is simple and highly effective. A single shot of penicillin cures the disease. Anyone allergic to penicillin can be treated with another antibiotic, usually erythromycin or tetracycline.
Yaws is a major public health problem in the tropics. Tropical regions in Central and South America, Africa, Asia, and Polynesia are at risk for yaws. A high percentage of children can be infected. Transmission of the disease is facilitated by overcrowding and poor hygiene, in the favellas of the cities of northeastern Brazil.
Yaws can be completely eradicated from an area by giving penicillin or another appropriate antibiotic to everyone in the population. This may, unfortunately, cost more than a poor country can afford.
The term "yaws" is of Caribbean origin. Because the bumps of yaws look like little berries, the disease is also called frambesia (or frambesia tropica) from the French "framboise" meaning "raspberry." Other names include granuloma tropicum polypapilloma tropicum, and thymiosis.
Yawning
Yawning: Involuntary opening of the mouth with respiration, breathing first inward, then outward. Yawning is often caused by the power of suggestion. Repeated yawning may be a sign of drowsiness. It can also sometimes be a sign of depression.
Yawn
Yawn: Involuntary opening of the mouth, often caused by suggestion. Yawning is characterized by breathing first inward, then outward.
Repeated yawning is often a sign of drowsiness. It may also sometimes be a sign of depression.
Repeated yawning is often a sign of drowsiness. It may also sometimes be a sign of depression.
Yard
Yard: In length, 3 feet or 36 inches or, metrically, 91.44 centimeters. The yard, along with the foot and inch, are English creations to which the USA has stubbornly clung. The yard was originally a unit of measurement of land and was about 5 meters (now termed a rod). In the 14th century, the yard emerged as 3 feet, about the length of a riding stick or sword.
YAG laser surgery
YAG laser surgery: The use of a YAG (yttrium-aluminum-garnet) laser to do surgery.
One use for a YAG laser in surgery is to punch a hole in the iris to relieve increased pressure within the eye from acute angle-closure glaucoma. In this type of glaucoma, there is a sudden (acute) increase in pressure in the anterior (front) chamber of the eye due to abrupt blockage of the normal circulation of fluid within the eye.
There are other kinds of YAG laser surgery for the eye (e.g., for cataracts) and other areas of the body including the skin (e.g., to remove birth marks).
YAG laser surgery is an office procedure. It is also used in some hospital procedures including laparoscopy for endometriosis.
One use for a YAG laser in surgery is to punch a hole in the iris to relieve increased pressure within the eye from acute angle-closure glaucoma. In this type of glaucoma, there is a sudden (acute) increase in pressure in the anterior (front) chamber of the eye due to abrupt blockage of the normal circulation of fluid within the eye.
There are other kinds of YAG laser surgery for the eye (e.g., for cataracts) and other areas of the body including the skin (e.g., to remove birth marks).
YAG laser surgery is an office procedure. It is also used in some hospital procedures including laparoscopy for endometriosis.
YAC
YAC:YAC stands for yeast artificial chromosome, a vector (carrier) created and used in the laboratory to clone pieces of DNA.
A YAC is constructed from the telomeric, centromeric, and replication origin sequences needed for replication in yeast cells. (The telomere is the end of the chromosome; the centromere is the chromosome region to which spindle fibers attach during cell division; and the replication origin sequences are the spots where the replication of DNA starts.)
A YAC is constructed from the telomeric, centromeric, and replication origin sequences needed for replication in yeast cells. (The telomere is the end of the chromosome; the centromere is the chromosome region to which spindle fibers attach during cell division; and the replication origin sequences are the spots where the replication of DNA starts.)
Y. pestis
Y. pestis: Yersinia pestis, the bacteria that causes the bubonic plague which in the year 541 (as the Black Death) and later in the Middle Ages decimated Europe. The effects of the plague are described in the nursery rhyme "We all fall down."
Y. pestis mainly infects rats and other rodents which are the prime reservoir for the bacteria. Fleas are the prime vectors carrying the bacteria from one species to another. They bite rodents infected with Y. pestis, then they bite people and so transmit the disease to them.
Transmission of the plague to people can also occur from eating infected animals such as squirrels. Once someone has the plague, they can transmit it to another person via aerosol droplets.
Plague occurs in the U.S. It is treatable with antibiotics but, if not treated promptly, can promptly lead to death.
Yersinia is named after the Swiss bacteriologist Alexandre- Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. The bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako.
Y. pestis mainly infects rats and other rodents which are the prime reservoir for the bacteria. Fleas are the prime vectors carrying the bacteria from one species to another. They bite rodents infected with Y. pestis, then they bite people and so transmit the disease to them.
Transmission of the plague to people can also occur from eating infected animals such as squirrels. Once someone has the plague, they can transmit it to another person via aerosol droplets.
Plague occurs in the U.S. It is treatable with antibiotics but, if not treated promptly, can promptly lead to death.
Yersinia is named after the Swiss bacteriologist Alexandre- Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. The bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako.
Y-linked inheritance
Y-linked inheritance: Inheritance of genes on the Y chromosome. Since only males normally have a Y chromosome, Y-linked genes can only be transmitted from father to son.
Y-linked inheritance is also called holandric inheritance.
It has often been said that little is known about Y-linked inheritance. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome
Y-linked inheritance is also called holandric inheritance.
It has often been said that little is known about Y-linked inheritance. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome
Y-linked gene
Y-linked gene: A gene on the Y chromosome.
(Y-linkage is analogous to X-linkage (the presence of a gene on the X chromosome) in that it says a gene is on one of the sex chromosomes.)
It has often been said that little is known about genes that may be Y-linked. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
(Y-linkage is analogous to X-linkage (the presence of a gene on the X chromosome) in that it says a gene is on one of the sex chromosomes.)
It has often been said that little is known about genes that may be Y-linked. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
Y-linked
Y-linked: A gene on the Y chromosome. A Y-linked gene is by necessity passed from father to son, since the Y chromosome can only be transmitted by a man to his male progeny.
It has often been said that little is known about whether specific genes are or are not Y-linked. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
It has often been said that little is known about whether specific genes are or are not Y-linked. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
Y-linkage
Y-linkage: The presence of a gene on the Y chromosome. Y-linkage is analogous to X-linkage (the presence of a gene on the X chromosome) in that it says a gene is on one of the sex chromosomes.
It has often been said that little is known about Y-linkage. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome)
It has often been said that little is known about Y-linkage. This is no longer true. As of the year 2000, a number of genes were known to be Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome)
Y sex-determining region
Y sex-determining region: A region on the Y chromosome that determines the sex of the individual. This region goes by the symbol SRY (sex region Y). SRY is necessary and sufficient for male sex determination. It is the testis-determining factor.
Mutations in SRY give rise to XY females with gonadal dysgenesis who appear to be normal females at birth, but at puberty do not develop secondary sexual characteristics (breasts, etc.), do not menstruate, and have streak (fibrous) gonads without eggs. There is a high incidence of neoplasia (gonadoblastoma and germinoma) in the streak gonads.
Translocation (transfer) of the part of the Y chromosome containing SRY to the X chromosome results in XX males -- individuals who have XX sex chromosomes but appear male.
SRY resides in chromosome band Yp11.3 and encodes a transcription factor that is a member of the high mobility group (HMG)-box family of DNA binding proteins.
Mutations in SRY give rise to XY females with gonadal dysgenesis who appear to be normal females at birth, but at puberty do not develop secondary sexual characteristics (breasts, etc.), do not menstruate, and have streak (fibrous) gonads without eggs. There is a high incidence of neoplasia (gonadoblastoma and germinoma) in the streak gonads.
Translocation (transfer) of the part of the Y chromosome containing SRY to the X chromosome results in XX males -- individuals who have XX sex chromosomes but appear male.
SRY resides in chromosome band Yp11.3 and encodes a transcription factor that is a member of the high mobility group (HMG)-box family of DNA binding proteins.
Y map
Y map: The array of genes on the Y chromosome.
Once thought to be a genetic wasteland, the Y now is known to contain at least 20 genes. Some of these genes are unique to the Y including the Y-chromosome sex-determining region and male fitness genes that are active only in the testis and are thought responsible for the formation of sperm. Other genes on the Y have counterparts on the X chromosome, are active in many body tissues and play crucial "housekeeping" roles within the cell.
Once thought to be a genetic wasteland, the Y now is known to contain at least 20 genes. Some of these genes are unique to the Y including the Y-chromosome sex-determining region and male fitness genes that are active only in the testis and are thought responsible for the formation of sperm. Other genes on the Y have counterparts on the X chromosome, are active in many body tissues and play crucial "housekeeping" roles within the cell.
Y chromosome infertility
Y chromosome infertility: Male infertility with oligozoospermia (a subnormal number of sperm) or azoospermia (the absence of sperm) caused by deletion or rearrangement of the long arm of the Y chromosome, as demonstrated by chromosome analysis or by molecular studies which may show microdeletions (of region AZFa, AZFb, or AZFc) of the Y chromosome. Y chromosome infertility is considered as a diagnostic possibility when an otherwise healthy male proves to be infertile.
Y chromosome
Y chromosome: The sex chromosome found together with an X chromosome in most normal males. Once thought to be a genetic wasteland, the Y now is known to contain at least 20 genes, some of them unique to the Y including the male-determining gene and male fitness genes that are active only in the testis and are thought responsible for the formation of sperm. Other genes on the Y have counterparts on the X chromosome, are active in many body tissues and play crucial "housekeeping" roles with the cell.
A number of specific genes have been Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
The Y is a useful chromosome for tracking men because it is transmitted unchanged from father to son. The Y escapes the intergenerational shuffle (recombination) that affects genes on the X chromosome and the remainder of the genome. All men have essentially the same Y chromosome. It is thought that in our small ancestral population some men had no children or only daughters, so that some Y chromosomes disappeared until only one was left. This ubiquitous Y has the same DNA in every man on earth except for the mutation that crops up every millenium and is then inherited by all males descended from that man.
A number of specific genes have been Y-linked including:
ASMTY (which stands for acetylserotonin methyltransferase),
TSPY (testis-specific protein),
IL3RAY (interleukin-3 receptor),
SRY (sex-determining region),
TDF (testis determining factor),
ZFY (zinc finger protein), PRKY (protein kinase, Y-linked),
AMGL (amelogenin),
CSF2RY (granulocyte-macrophage colony-stimulating factor receptor, alpha subunit on the Y chromosome),
ANT3Y (adenine nucleotide translocator-3 on the Y),
AZF2 (azoospermia factor 2),
BPY2 (basic protein on the Y chromosome),
AZF1 (azoospermia factor 1),
DAZ (deleted in azoospermia),
RBM1 (RNA binding motif protein, Y chromosome, family 1, member A1),
RBM2 (RNA binding motif protein 2) and
UTY (ubiquitously transcribed TPR gene on Y chromosome).
The Y is a useful chromosome for tracking men because it is transmitted unchanged from father to son. The Y escapes the intergenerational shuffle (recombination) that affects genes on the X chromosome and the remainder of the genome. All men have essentially the same Y chromosome. It is thought that in our small ancestral population some men had no children or only daughters, so that some Y chromosomes disappeared until only one was left. This ubiquitous Y has the same DNA in every man on earth except for the mutation that crops up every millenium and is then inherited by all males descended from that man.
Y chromatin
Y chromatin: A brilliantly fluorescent body seen under the microscope in cells containing a Y chromosome when the cells are stained with the dye quinacrine. Quinacrine lights up the Y chromosome more than other chromosomes.
Y (in genetics)
Y (in genetics): The Y chromosome, the sex chromosome found in normal males, together with an X chromosome.
Y (in chemistry)
Y (in chemistry): The symbol for the element yttrium, an ultrarare metal named after Ytterby in southern Sweden. Yttrium has been used in certain nuclear medicine scans.
XYY syndrome
XYY syndrome: A chromosomal disorder that affects males only, caused by the presence of an extra Y chromosome. Symptoms may include increased height, speech delays, learning disabilities, mild to moderate mental retardation, and behavioral disturbance. Also known as polysomy Y syndrome.
Xylitol
A sweetener found in plants that is used as a substitute for sugar. Xylitol is considered a nutritive sweetener because it provides calories, just like sugar. (Saccharin is an example of a nonnutritive sweetener, one that has no calories.)
XXXX syndrome
XXXX syndrome: A chromosome disorder in females caused by the presence of four X chromosomes rather than the usual two. The disorder is characterized by decreased intelligence (IQ 30 to 80; average 55), speech and behavioral problems, tall stature and reduced fertility. Also known as tetra-X syndrome.
XXX syndrome
XXX syndrome: A chromosome condition present in 1 in 1000 females, due to the presence of three X chromosomes rather than the usual two. The condition is associated with increased height but no malformations. Intelligence ranges from above normal to mild retardation. The average IQ is 85 to 90. Learning problems may be helped by early special education. Also known as triple X; triplo-X.
XX male syndrome
XX male syndrome: A syndrome characterized by the presence of an XX sex chromosome complement in an individual with male genitalia including both testes but no sperm production (azoospermia).
Babies with the XX male syndrome may come to medical attention at birth because of hypospadias (urethral opening not at its normal position at the end of the penis) or because of cryptorchidism (undescended testes). However, most individuals with the syndrome have a normal penis and their testes in the scrotum and do not come to medical attention until after puberty and only then perhaps because of the small size of their testes, gynecomastia (breast development in an apparent male), or sterility resulting from the azoospermia.
Some but not all individuals with the syndrome have SRY, the gene normally found on the Y chromosome that makes for malesness. This is often due to an abnormal interchange between the Y chromosome and the X chromosome, resulting in presence of the SRY gene on the X chromosome and infertility. It may also be due to translocation of SRY to an autosome (a non-sex chromosome). The X/autosome translocation can occur de novo (be new) or be inherited from a parent.
The XX male syndrome is also called de la Chapelle syndrome after the Finnish physician Albert de la Chapelle who first described it.
Babies with the XX male syndrome may come to medical attention at birth because of hypospadias (urethral opening not at its normal position at the end of the penis) or because of cryptorchidism (undescended testes). However, most individuals with the syndrome have a normal penis and their testes in the scrotum and do not come to medical attention until after puberty and only then perhaps because of the small size of their testes, gynecomastia (breast development in an apparent male), or sterility resulting from the azoospermia.
Some but not all individuals with the syndrome have SRY, the gene normally found on the Y chromosome that makes for malesness. This is often due to an abnormal interchange between the Y chromosome and the X chromosome, resulting in presence of the SRY gene on the X chromosome and infertility. It may also be due to translocation of SRY to an autosome (a non-sex chromosome). The X/autosome translocation can occur de novo (be new) or be inherited from a parent.
The XX male syndrome is also called de la Chapelle syndrome after the Finnish physician Albert de la Chapelle who first described it.
XX gonadal dysgenesis with sensorineural deafness
XX gonadal dysgenesis with sensorineural deafness: See Perrault syndrome
Xuezhikang
Xuezhikang: One of the three major preparations of red yeast rice, a tradition Chinese medicine now used to lower cholesterol.
Xiphoid process
Xiphoid process: A pointed cartilage attached to the lower end of the breastbone or sternum, the smallest and lowest division of the sternum. Cartilaginous early in life, it may become ossified (bony) in adults. It is sometimes simply called the xiphoid. Also known as the ensiform cartilage or process.
The ancients thought the xiphoid looked like the tip of a sword. The word "xiphoid" is from the Greek "xiphos" (straight sword) + "eidos" (like) = straight sword. "Ensiform" is from the Latin "ensis" (sword) + "forma" (shape) = sword shape.
The ancients thought the xiphoid looked like the tip of a sword. The word "xiphoid" is from the Greek "xiphos" (straight sword) + "eidos" (like) = straight sword. "Ensiform" is from the Latin "ensis" (sword) + "forma" (shape) = sword shape.
Xerostomia
Xerostomia: Dry mouth. The condition of not having enough saliva to keep the mouth wet due to inadequate function of the salivary glands. Everyone has a dry mouth once in a while when they are nervous, upset or under stress. But if someone has a dry mouth all or most of the time, it can be uncomfortable and can lead to serious health problems. Dry mouth can cause difficulties in tasting, chewing, swallowing, and speaking. If it goes untreated, severe dry mouth can also lead to increased levels of tooth decay and infections of the mouth such as thrush.
Severe dry mouth is not a normal part of aging. It can be a clue to serious systemic diseases such as Sjogren syndrome, systemic lupus erythematosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, and hypothyroidism.
The word xerostomia reflects its Greek origins from "xeros" (dry) + "stoma" (mouth).
Severe dry mouth is not a normal part of aging. It can be a clue to serious systemic diseases such as Sjogren syndrome, systemic lupus erythematosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, and hypothyroidism.
The word xerostomia reflects its Greek origins from "xeros" (dry) + "stoma" (mouth).
Xerosis
Xerosis: Abnormal dryness of the skin (xeroderma), of the conjunctiva of the eye (xerophthalmia), or of the mucous membranes such as dry mouth (xerostomia).
The word "xerosis" literally means "dry condition." It was compounded from the Greek roots "xero-" (dry) and "-osis" (condition).
The word "xerosis" literally means "dry condition." It was compounded from the Greek roots "xero-" (dry) and "-osis" (condition).
Xeromammography
Xeromammography: Xeroradiography of the breast. Xeroradiography is a photoelectric method of recording an x-ray image on a coated metal plate, using low-energy photon beams, long exposure time and dry chemical developers.
The prefix xero- comes from the Greek "xeros" meaning "dry."
The prefix xero- comes from the Greek "xeros" meaning "dry."
Xerogram
Xerogram: A picture of the body recorded on paper rather than on film. Also called a xeroradiograph.
From the Greek "xeros" meaning "dry."
From the Greek "xeros" meaning "dry."
Xeroderma pigmentosum
Xeroderma pigmentosum: A genetic disease characterized by such extraordinary sensitivity to sunlight that it results in the development of skin cancer at a very early age. Children with xeroderma pigmentosum (XP) can only play outdoors safely after nightfall. They have been called midnight children, the children of the dark, the children of the night and, perjoratively, vampire children.
XP is due to defective repair of damage done to DNA (the genetic material), damage caused by ultraviolet (UV) light. Whereas normal persons can repair UV-induced damage by inserting new bases into the DNA, XP patients lack the normal capacity to repair the DNA damage inflicted by UV light.
A person with XP develops severe sunburn and eye irritation within minutes of exposure to sunlight. Other signs of XP include the development of ultradry skin (the word "xeroderma" means extreme dryness of the skin) plus blisters, heavy freckling and dark spots on the skin (the word "pigmentosum" refers to these pigmented areas of skin).
Damage to DNA is cumulative; it is additive and cannot be reversed. Recurrent exposure of a XP person to UV light can cause the rapid development of cancerous and non-cancerous growths on both the skin and eyes. Even children with XP can develop skin cancer. About one in every five XP patients also develops one or more of the following problems: blindness, deafness, mental retardation, poor coordination, spasticity, or retarded physical growth.
The life span of XP patients varies. Those with undiagnosed XP who regularly expose themselves to sunlight may die young of skin cancer. Those with a diagnosis of XP who protect themselves from sunlight may live a long life. The life expectancy of most patients falls between these extremes.
Diagnosis requires tests on skin or blood samples. Although the disease itself is incurable, patients can maintain their health by:
protecting themselves completely from ultraviolet light,
getting frequent skin and eye examinations, and
having cancerous growths removed without delay.
XP is inherited as an autosomal recessive trait (meaning that the gene for XP is on a nonsex chromosome [an autosome] and that a person must possess two doses of that gene to manifest the syndrome). In actuality, XP is not one disease. A number of diseases clinically paint the XP picture. Genes for XP reside in diverse locations including chromosomes 3p25, 9q22.3, 11p12-p11, and 19q13.2-q13.3.
XP is due to defective repair of damage done to DNA (the genetic material), damage caused by ultraviolet (UV) light. Whereas normal persons can repair UV-induced damage by inserting new bases into the DNA, XP patients lack the normal capacity to repair the DNA damage inflicted by UV light.
A person with XP develops severe sunburn and eye irritation within minutes of exposure to sunlight. Other signs of XP include the development of ultradry skin (the word "xeroderma" means extreme dryness of the skin) plus blisters, heavy freckling and dark spots on the skin (the word "pigmentosum" refers to these pigmented areas of skin).
Damage to DNA is cumulative; it is additive and cannot be reversed. Recurrent exposure of a XP person to UV light can cause the rapid development of cancerous and non-cancerous growths on both the skin and eyes. Even children with XP can develop skin cancer. About one in every five XP patients also develops one or more of the following problems: blindness, deafness, mental retardation, poor coordination, spasticity, or retarded physical growth.
The life span of XP patients varies. Those with undiagnosed XP who regularly expose themselves to sunlight may die young of skin cancer. Those with a diagnosis of XP who protect themselves from sunlight may live a long life. The life expectancy of most patients falls between these extremes.
Diagnosis requires tests on skin or blood samples. Although the disease itself is incurable, patients can maintain their health by:
protecting themselves completely from ultraviolet light,
getting frequent skin and eye examinations, and
having cancerous growths removed without delay.
XP is inherited as an autosomal recessive trait (meaning that the gene for XP is on a nonsex chromosome [an autosome] and that a person must possess two doses of that gene to manifest the syndrome). In actuality, XP is not one disease. A number of diseases clinically paint the XP picture. Genes for XP reside in diverse locations including chromosomes 3p25, 9q22.3, 11p12-p11, and 19q13.2-q13.3.
Xeroderma
Xeroderma: Abnormally dry skin.
Xeroderma can be caused by a deficiency of vitamin A, systemic illness, overexposure to sunlight, or medication.
It can usually be addressed by the use of over-the-counter (OTC) topical preparations. If these products do not relieve the condition, see an aesthetician or dermatologist for more specific remedies.
From the Greek "xeros" meaning "dry" + the Greek "derma" meaning "skin" = dry skin.
Xeroderma can be caused by a deficiency of vitamin A, systemic illness, overexposure to sunlight, or medication.
It can usually be addressed by the use of over-the-counter (OTC) topical preparations. If these products do not relieve the condition, see an aesthetician or dermatologist for more specific remedies.
From the Greek "xeros" meaning "dry" + the Greek "derma" meaning "skin" = dry skin.
Xero-
Xero- (prefix): Dry. From the Greek "xeros" meaning "dry."
Examples of words containing "xero-" -- xeroderma is dry skin; xerophagia is eating a dry diet; xerophthalmia is dry eye; and xerostomia.
Examples of words containing "xero-" -- xeroderma is dry skin; xerophagia is eating a dry diet; xerophthalmia is dry eye; and xerostomia.
Xeric
Xeric: Characterized by a scanty supply of moisture (or tolerating or adapted to dry conditions).
The word "xeric" is derived from "xeros," the Greek word for "dry." "Xeric" was coined in 1926 and was in common scientific usage by the 1940s.
The word "xeric" is derived from "xeros," the Greek word for "dry." "Xeric" was coined in 1926 and was in common scientific usage by the 1940s.
Xenotropic virus
Xenotropic virus: A virus that can grow in the cells of a species foreign to the normal host species, a species different from that which normally hosts it.
Xeno- means foreign while -tropic refers to growth. So xeno- + -tropic = capable of growing in a foreign environment.
Xeno- means foreign while -tropic refers to growth. So xeno- + -tropic = capable of growing in a foreign environment.
Xenotransplantation
Xenotransplantation: Transplantation from one species to a foreign one. The rationale for xenotransplantation has included the short supply of human organs for transplantation.
The first surgeon to do an animal-to-human heart transplant was Dr. James D. Hardy. After doing the first human lung transplant in 1963, Hardy did the first animal-to-human heart transplant in 1964 at the University of Mississippi. The transplant involving a chimpanzee heart was done three years before the first human-heart transplant (by Christiaan Barnard).
Perhaps the most famous case of cross-species transplantation was that of a heart from a baboon to Baby Fae in 1984, performed by Dr. Leonard Bailey at Loma Linda University, California. Baby Fae lived for 20 days after the operation.
The first to show that nonhuman organs could be transplanted to humans and function for a significant period of time was Dr. Keith Reemtsma (1925-2000). At Tulane University in New Orleans Dr. Reemtsma in 1963 and 1964 gave chimpanzee kidneys to 5 patients in the first chimpanzee-to-human transplants. The recipients died (of infection) from 8 to 63 days after receiving a chimpanzee kidney. Then, in 1964 Reemtsma transplanted a kidney from a chimpanzee to a 23-year-old teacher. She lived with it for 9 months until succumbing to overwhelming infection.
The prefix "xeno-" means foreign. It comes from the Greek word "xenos" meaning stranger, guest, or host. (Xenophobia is fear of foreigners). Xenotransplantation is synonymous with cross-species transplantation.
The first surgeon to do an animal-to-human heart transplant was Dr. James D. Hardy. After doing the first human lung transplant in 1963, Hardy did the first animal-to-human heart transplant in 1964 at the University of Mississippi. The transplant involving a chimpanzee heart was done three years before the first human-heart transplant (by Christiaan Barnard).
Perhaps the most famous case of cross-species transplantation was that of a heart from a baboon to Baby Fae in 1984, performed by Dr. Leonard Bailey at Loma Linda University, California. Baby Fae lived for 20 days after the operation.
The first to show that nonhuman organs could be transplanted to humans and function for a significant period of time was Dr. Keith Reemtsma (1925-2000). At Tulane University in New Orleans Dr. Reemtsma in 1963 and 1964 gave chimpanzee kidneys to 5 patients in the first chimpanzee-to-human transplants. The recipients died (of infection) from 8 to 63 days after receiving a chimpanzee kidney. Then, in 1964 Reemtsma transplanted a kidney from a chimpanzee to a 23-year-old teacher. She lived with it for 9 months until succumbing to overwhelming infection.
The prefix "xeno-" means foreign. It comes from the Greek word "xenos" meaning stranger, guest, or host. (Xenophobia is fear of foreigners). Xenotransplantation is synonymous with cross-species transplantation.
Xenograft
Xenograft: A surgical graft of tissue from one species to an unlike species (or genus or family). A graft from a baboon to a human is a xenograft.
The prefix "xeno-" means foreign. It comes from the Greek word "xenos" meaning stranger, guest, or host. (Xeno- and xen- are variant forms of the same prefix.)
The prefix "xeno-" means foreign. It comes from the Greek word "xenos" meaning stranger, guest, or host. (Xeno- and xen- are variant forms of the same prefix.)
Xenoantigen
Xenoantigen: An antigen that is found in more than one species. An antigen is something that is capable of inducing an immune response.
The prefix "xeno-" means foreign or other. It comes from the Greek "xenos" meaning stranger, guest, or host.
The prefix "xeno-" means foreign or other. It comes from the Greek "xenos" meaning stranger, guest, or host.
Xeno- (prefix)
Xeno- (prefix): Foreign or other. As in:
Xenoantigen -- An antigen that is found in more than one species.
Xenograft -- A surgical graft of tissue from one species an unlike species, genus or family.
Xenotransplantation -- Transplantation from one species to a foreign one, e.g., the heart transplant from a baboon to Baby Fae in 1984 in Loma Linda, California.
Xenotropic virus -- A virus that can grow in the cells of a species foreign to the normal host species.
The origin of "xeno-" is from the Late Latin, from Greek, from "xenos" meaning stranger, guest, or host. Xeno- and xen- are variant forms of the same prefix.
Xenoantigen -- An antigen that is found in more than one species.
Xenograft -- A surgical graft of tissue from one species an unlike species, genus or family.
Xenotransplantation -- Transplantation from one species to a foreign one, e.g., the heart transplant from a baboon to Baby Fae in 1984 in Loma Linda, California.
Xenotropic virus -- A virus that can grow in the cells of a species foreign to the normal host species.
The origin of "xeno-" is from the Late Latin, from Greek, from "xenos" meaning stranger, guest, or host. Xeno- and xen- are variant forms of the same prefix.
Xen- (prefix)
Xen- (prefix): Foreign or other. As in:
Xenoantigen -- An antigen that is found in more than one species.
Xenograft -- A surgical graft of tissue from one species to an unlike species, genus or family.
Xenotransplantation -- Transplantation from one species to a foreign one, e.g., the heart transplant from a baboon to Baby Fae in 1984 at Loma Linda University, California.
Xenotropic virus -- A virus that can grow in the cells of a species foreign to the normal host species.
The origin of "xen-" is from the Late Latin, from Greek, from "xenos" meaning stranger, guest, or host. Xen- and xeno- are variant forms of the same prefix.
Xenoantigen -- An antigen that is found in more than one species.
Xenograft -- A surgical graft of tissue from one species to an unlike species, genus or family.
Xenotransplantation -- Transplantation from one species to a foreign one, e.g., the heart transplant from a baboon to Baby Fae in 1984 at Loma Linda University, California.
Xenotropic virus -- A virus that can grow in the cells of a species foreign to the normal host species.
The origin of "xen-" is from the Late Latin, from Greek, from "xenos" meaning stranger, guest, or host. Xen- and xeno- are variant forms of the same prefix.
Xanthosis
Xanthosis: Yellowing of the skin without yellowing of the eyes. In jaundice there is yellowing of both the skin and the whites of the eyes. Xanthosis is associated sometimes with malignancies.
Xanthopsia
Xanthopsia: A form of chromatopsia, a visual defect in which objects appear as if they have been overpainted with an unnatural color. In xanthopsia, that color is yellow.
Xanthomatosis
Xanthomatosis: A condition in which fatty deposits occur in various parts of the body. These fatty deposits are called xanthomas or xanthomata and appear as yellowish firm nodules in the skin. Xanthomas are in themselves a harmless growth of tissue. However, they frequently indicate the presence of underlying diseases such as diabetes and disorders of fats (lipid disorder or hyperlipidemia).
Under the microscope, a xanthoma consists of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
Under the microscope, a xanthoma consists of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
Xanthoma, planar
Xanthoma, planar: A type of xanthoma characterized by flat yellow-to-orange patches or pimples that cluster together on the skin.
Xanthoma, disseminatum
Xanthoma, disseminatum: A type of xanthoma characterized by orange-to-brown nodules on the skin or mucus membranes.
Xanthoma tuberosum
Xanthoma tuberosum: Xanthoma that clusters near joints. It is associated with lipid disorders, cirrhosis of the liver, and thyroid disorders.
Xanthoma tendinosum
Xanthoma tendinosum: Xanthoma that clusters around tendons, and is associated with lipid disorders.
Xanthoma
Xanthoma: Yellowish firm nodules in the skin frequently indicating underlying disease, such as diabetes, disorder of fats (lipid disorder or hyperlipidemia), or other conditions. A xanthoma is a kind of harmless growth of tissue.
Under the microscope, a xanthoma can be seen to be composed of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
The word "xanthoma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "oma" (swelling) = a yellow swelling. A xanthoma is a circumscribed yellow swelling, a yellowish nodule.
Under the microscope, a xanthoma can be seen to be composed of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
The word "xanthoma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "oma" (swelling) = a yellow swelling. A xanthoma is a circumscribed yellow swelling, a yellowish nodule.
Xanthinuria
Xanthinuria: An inherited metabolic disorder in which there is deficiency of an enzyme needed to process xanthine, a substance found in caffeine, theobromine, theophylline, and related substances. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle). Treatment is by avoiding foods and drinks containing xanthine derivatives, such as coffee, tea, and colas.
The enzyme that is lacking in xanthinuria is xanthine dehydrogenase. The disorder is an autosomal recessive trait. The gene responsible for xanthinuria is on an autosome, a nonsex chromosome (chromosome 2p23-p22). Both parents of a child with xanthinuria are normal but carry one xanthinuria gene (the xanthinuria gene is recessive to the corresponding normal gene). Their affected child received both of their xanthinuria genes.
The enzyme that is lacking in xanthinuria is xanthine dehydrogenase. The disorder is an autosomal recessive trait. The gene responsible for xanthinuria is on an autosome, a nonsex chromosome (chromosome 2p23-p22). Both parents of a child with xanthinuria are normal but carry one xanthinuria gene (the xanthinuria gene is recessive to the corresponding normal gene). Their affected child received both of their xanthinuria genes.
Xanthine
Xanthine: A substance found in caffeine, theobromine, and theophylline and encountered in tea, coffee, and the colas. Chemically, xanthine is a purine.
There is a genetic disease of xanthine metabolism, xanthinuria, due to deficiency of an enzyme, xanthine dehydrogenase, needed to process xanthine in the body. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle). Treatment is by avoiding foods and drinks containing xanthine derivatives, such as coffee, tea, and colas.
The name "xanthine" was taken from the Greek "xanqos" meaning yellow + quinine since it forms yellow salts and its solution forms a blue fluorescence as does quinine.
There is a genetic disease of xanthine metabolism, xanthinuria, due to deficiency of an enzyme, xanthine dehydrogenase, needed to process xanthine in the body. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle). Treatment is by avoiding foods and drinks containing xanthine derivatives, such as coffee, tea, and colas.
The name "xanthine" was taken from the Greek "xanqos" meaning yellow + quinine since it forms yellow salts and its solution forms a blue fluorescence as does quinine.
Xanthelasma
Xanthelasma: Tiny (1-2 mm) yellowish plaques that are slightly raised on the skin surface of the upper or lower eyelids. Xanthelasma is caused by tiny deposits of fat in the skin and is often associated with abnormal blood fat levels (hyperlipidemia). Xanthelasma is a kind of minute harmless growth of tissue. Xanthelasma typically appears in or near the eyelids.
Under the microscope, Xanthelasma can be seen to be composed of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
The word "xanthelasma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "elasma" (plate) = a yellow plate, so called because these are yellow plaques.
Under the microscope, Xanthelasma can be seen to be composed of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).
The word "xanthelasma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "elasma" (plate) = a yellow plate, so called because these are yellow plaques.
Xanth- (prefix)
Xanth- (prefix): A colorful prefix relating to a yellow color. "Xanth-" is related to the word "xanthic" which has its roots in the Greek word "xanthos" which means yellow.
A number of medical terms trace to "xanthos" including, for example:
Xanthelasma: A condition in which tiny (1-2 mm) yellowish plaques that are slightly raised on the skin surface of the upper or lower eyelids. The word "xanthelasma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "elasma" (plate) = a yellow plate, so called because these are yellow plaques.
Xanthinuria: Literally "yellow urine," xanthinuria is an inherited metabolic disorder in which there is deficiency of an enzyme needed to process xanthine, a yellowish substance found in caffeine, theobromine, theophylline, and related substances. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle).
Xanthoma: A condition characterized by yellowish firm nodules in the skin that frequently are a sign of an underlying disease such as diabetes or a disorder of fats (lipid disorder or hyperlipidemia). The word "xanthoma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "oma" (swelling) = a yellow swelling.
"Xanth" is more than a prefix. It is a combining term and can be at the front, in the middle, or at the end of a word. For example, in "pseudoxanthoma
A number of medical terms trace to "xanthos" including, for example:
Xanthelasma: A condition in which tiny (1-2 mm) yellowish plaques that are slightly raised on the skin surface of the upper or lower eyelids. The word "xanthelasma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "elasma" (plate) = a yellow plate, so called because these are yellow plaques.
Xanthinuria: Literally "yellow urine," xanthinuria is an inherited metabolic disorder in which there is deficiency of an enzyme needed to process xanthine, a yellowish substance found in caffeine, theobromine, theophylline, and related substances. Unchecked, xanthinuria can lead to kidney stone formation and urinary tract disease (due to xanthine stones) and to muscle disease (due to deposits of xanthine in the muscle).
Xanthoma: A condition characterized by yellowish firm nodules in the skin that frequently are a sign of an underlying disease such as diabetes or a disorder of fats (lipid disorder or hyperlipidemia). The word "xanthoma" is made up of "xanth-" from the Greek roots "xanthos" (yellow) and "oma" (swelling) = a yellow swelling.
"Xanth" is more than a prefix. It is a combining term and can be at the front, in the middle, or at the end of a word. For example, in "pseudoxanthoma
X-ray, PA
X-ray, PA: An X-ray picture in which the beams pass from back-to-front (posteroanterior). By contrast an AP (anteroposterior) film is one in which the rays pass through the body from front-to-back.
X-ray, AP
X-ray, AP: An X-ray picture in which the beams pass from front-to-back (anteroposterior). An AP film is as opposed to a PA (posteroanterior) film in which the rays pass through the body from back-to-front.
X-ray crystallography
X-ray crystallography: The use of X-rays of known wavelength to learn the structure of any crystalline material. Put otherwise, X-ray crystallography is a technology by which the locations of atoms in any crystal can be precisely mapped by looking at the image of the crystal under an X-ray beam.
The crystal is placed in the beam of X-rays and the angles of diffraction of the X-rays are recorded as a series of spots on photographic film. This method (called the Laue method after the German physicist Max Theodor Felix von Laue) has been employed to determine and measure the physical structure of many materials.
One example of the use of X-ray crystallography has been our understanding of the structure and function of hemoglobin and its close relative, myoglobin. Hemoglobin is the protein that transports oxygen from the lungs to the tissues via red blood cells while myoglobin is its counterpart in muscle that stores oxygen and gives it up to muscle cells as needed.
In 1962 Max Perutz and John C. Kendrew from Cambridge University shared the Nobel Prize for Chemistry for their brilliant X-ray diffraction analyses of hemoglobin (Perutz) and myoglobin (Kendrew).
The crystal is placed in the beam of X-rays and the angles of diffraction of the X-rays are recorded as a series of spots on photographic film. This method (called the Laue method after the German physicist Max Theodor Felix von Laue) has been employed to determine and measure the physical structure of many materials.
One example of the use of X-ray crystallography has been our understanding of the structure and function of hemoglobin and its close relative, myoglobin. Hemoglobin is the protein that transports oxygen from the lungs to the tissues via red blood cells while myoglobin is its counterpart in muscle that stores oxygen and gives it up to muscle cells as needed.
In 1962 Max Perutz and John C. Kendrew from Cambridge University shared the Nobel Prize for Chemistry for their brilliant X-ray diffraction analyses of hemoglobin (Perutz) and myoglobin (Kendrew).
X-ray
X-ray: 1. High-energy radiation with waves shorter than those of visible light. X-rays possess the properties of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting radiography), and of causing a fluorescent screen to give off light (permitting fluoroscopy). In low doses X-rays are used for making images that help to diagnose disease, and in high doses to treat cancer. Formerly called a Roentgen ray. 2. An image obtained by means of X-rays.
X-linked
X-linked: On the X chromosome. "Linked" in genetics does not mean merely associated. An X-linked gene travels with the X chromosome and therefore is part of the X chromosome.
X, factor
X, factor: A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in band 13q34.
The "X" in factor X is the Roman numeral "ten." (All numbered coagulation factors bear Roman numerals.) Factor X became known because of a genetic condition in which the factor is lacking.
Factor X deficiency is inherited as an autosomal recessive trait manifest by prolonged nose bleeds, gastrointestinal hemorrhage, menorrhagia (abnormally heavy menstrual bleeding), hematuria (blood in the urine), and hemarthrosis (bleeding into joints). Pregnancy in women with factor X deficiency is often associated with adverse fetal outcomes (recurrent spontaneous abortion, placental abruption, and premature birth).
Factor X is also called Stuart-Prower factor because Mr. Stuart and Miss Prower were the first persons shown to have deficiency of this factor.
The "X" in factor X is the Roman numeral "ten." (All numbered coagulation factors bear Roman numerals.) Factor X became known because of a genetic condition in which the factor is lacking.
Factor X deficiency is inherited as an autosomal recessive trait manifest by prolonged nose bleeds, gastrointestinal hemorrhage, menorrhagia (abnormally heavy menstrual bleeding), hematuria (blood in the urine), and hemarthrosis (bleeding into joints). Pregnancy in women with factor X deficiency is often associated with adverse fetal outcomes (recurrent spontaneous abortion, placental abruption, and premature birth).
Factor X is also called Stuart-Prower factor because Mr. Stuart and Miss Prower were the first persons shown to have deficiency of this factor.
X inactivation
X inactivation: The phenomenon in a female by which one X chromosome (either the maternally or paternally derived X) is randomly (by chance) inactivated in an early embryonic cell, with fixed inactivation of that same X in all cells descended from that cell. The change that occurs with X inactivation is epigenetic: it is a heritable change in gene function without a change in the sequence of the DNA.
X inactivation is not restricted to females. It also occurs in males with Klinefelter syndrome who have more than one X chromosome.
The phenomenon of X inactivation is also called lyonization after the English geneticist Mary Lyon (1925-) who first described it.
X inactivation is not restricted to females. It also occurs in males with Klinefelter syndrome who have more than one X chromosome.
The phenomenon of X inactivation is also called lyonization after the English geneticist Mary Lyon (1925-) who first described it.
X chromosome
X chromosome: A sex chromosome found in both females and males. Normal females usually have two X chromosomes. Normal males usually have one X along with a Y chromosome. The complete chromosome complement consisting of 46 chromosomes is conventionally written as 46,XX for females and 46,XY for males.
The X chromosome carries hundreds of genes. Only a minority of the genes on the X have anything to do with sex. This is consistent with the concept that the X and Y chromosomes evolved from an ancient pair of autosomal (nonsex) chromosomes and that the X chromosome retains much of its old autosomal information.
The inheritance of genes on the X follows special rules because males have only a single X chromosome, almost no gene on the X has a counterpart on the Y, and genes on the X are expressed in males. Genes inherited in this manner are said to be sex-linked or, more precisely, X-linked.
Examples of the genes on the X chromosome include those for the enzyme steroid sulfatase, episodic muscle weakness, ocular albinism, Charcot-Marie-Tooth disease (one kind of this neurologic disease), retinoschisis (retinal splitting due to degeneration), infantile spasm syndrome, agammaglobulinemia (a form of immune deficiency), Aicardi syndrome, Duchenne and Becker muscular dystrophy, chronic granulomatous disease, hemophilia A, hemophilia B, and red-green colorblindness.
The X chromosome carries hundreds of genes. Only a minority of the genes on the X have anything to do with sex. This is consistent with the concept that the X and Y chromosomes evolved from an ancient pair of autosomal (nonsex) chromosomes and that the X chromosome retains much of its old autosomal information.
The inheritance of genes on the X follows special rules because males have only a single X chromosome, almost no gene on the X has a counterpart on the Y, and genes on the X are expressed in males. Genes inherited in this manner are said to be sex-linked or, more precisely, X-linked.
Examples of the genes on the X chromosome include those for the enzyme steroid sulfatase, episodic muscle weakness, ocular albinism, Charcot-Marie-Tooth disease (one kind of this neurologic disease), retinoschisis (retinal splitting due to degeneration), infantile spasm syndrome, agammaglobulinemia (a form of immune deficiency), Aicardi syndrome, Duchenne and Becker muscular dystrophy, chronic granulomatous disease, hemophilia A, hemophilia B, and red-green colorblindness.
X (in genetics)
X (in genetics): Although the letter X can be used as a symbol in various ways (such as with X-rays, the X-axis of a graph, etc.), "the X " in genetics and medicine today usually refers to the X chromosome.
The X is the sex chromosome that is found twice in chromosomally normal females and singly along with a Y chromosome in chromosomally normal males. The complete chromosome complement consisting of 46 chromosomes including the two sex chromosomes is thus conventionally written as 46,XX for chromosomally normal females and 46,XY for chromosomally normal males.
The X is the sex chromosome that is found twice in chromosomally normal females and singly along with a Y chromosome in chromosomally normal males. The complete chromosome complement consisting of 46 chromosomes including the two sex chromosomes is thus conventionally written as 46,XX for chromosomally normal females and 46,XY for chromosomally normal males.
X (drug caution code)
X (drug caution code): Abbreviation on a medication that indicates SOS -- that the medication contains a substance such as acetaminophen that could cause problems -- consult your pharmacist.
While not a part of the historical heritage of ancient prescription abbreviations, drug caution codes provide very valuable warnings.
If you see a caution code on a prescription, talk to your pharmacist about it before using the medicine.
While not a part of the historical heritage of ancient prescription abbreviations, drug caution codes provide very valuable warnings.
If you see a caution code on a prescription, talk to your pharmacist about it before using the medicine.
Wry neck
Wry neck: Medically called spasmodic torticollis, or torticollis. The most common of the focal dystonias. In torticollis, the muscles in the neck that control the position of the head are affected, causing the head to twist and turn to one side. In addition, the head may be pulled forward or backward.
Writer's cramp
Writer's cramp: A dystonia that affects the muscles of the hand and sometimes the forearm and only occurs during handwriting. Similar focal dystonias have also been called typist's cramp, pianist's cramp, musician's cramp, and golfer's cramp.
Wrist
Wrist: The proximal segment (the near part) of the hand consisting of the carpal bones and the associated soft parts.
The eight carpal bones are arranged in two rows and articulate (come together to form a joint) proximally (on their near ends) with the long bones of the forearm -- the radius and, indirectly, with the ulna -- and distally (on their far ends) with the five metacarpal bones that make up the palm's infrastructure.
The eight carpal bones are arranged in two rows and articulate (come together to form a joint) proximally (on their near ends) with the long bones of the forearm -- the radius and, indirectly, with the ulna -- and distally (on their far ends) with the five metacarpal bones that make up the palm's infrastructure.
WPW syndrome
WPW syndrome: Abbreviation for the Wolff-Parkinson-White syndrome, a condition caused by an abnormality in the electrical system of the heart which normally tells the heart muscle when to contract.
In the WPW syndrome, there is an extra electrical connection inside the heart that acts as a short circuit, causing the heart to beat too rapidly and sometimes in an irregular manner. The syndrome can be lifethreatening although this is unusual.
WPW can be treated by destroying the short circuit using a technique termed radiofrequency catheter ablation in which wires are placed in different places in the heart until the short circuit is found and can be destroyed with radiowaves.
Wolff-Parkinson-White is written with hyphens because the syndrome was not discovered by a Dr. Wolff Parkinson White but by three doctors: Louis Wolff, Sir John Parkinson, and Paul Dudley White.
In the WPW syndrome, there is an extra electrical connection inside the heart that acts as a short circuit, causing the heart to beat too rapidly and sometimes in an irregular manner. The syndrome can be lifethreatening although this is unusual.
WPW can be treated by destroying the short circuit using a technique termed radiofrequency catheter ablation in which wires are placed in different places in the heart until the short circuit is found and can be destroyed with radiowaves.
Wolff-Parkinson-White is written with hyphens because the syndrome was not discovered by a Dr. Wolff Parkinson White but by three doctors: Louis Wolff, Sir John Parkinson, and Paul Dudley White.
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