Argentaffinoma: A tumor which secretes large amounts of the hormone serotonin. Argentaffinoma is also called carcinoid tumor.
The tumor usually arises in the gastrointestinal tract, anywhere between the stomach and the rectum (the favorite spot is in the appendix) and from there may metastasize (spread) to the liver. In the liver the tumor produces and releases large quantities of serotonin into the systemic bloodstream.
The consequences are called the carcinoid syndrome. It is directly due to the serotonin and includes flushing and blushing, swelling of the face (especially around the eyes), flat angiomas (little collections of dilated blood vessels) on the skin, diarrhea, bronchial spasm, rapid pulse, low blood pressure and tricuspid and pulmonary stenosis (narrowing of the tricuspid and pulmonic valves of the heart), often with regurgitation.
One or more of four kinds of treatment are used for carcinoid tumors: surgery (to take out the cancer); radiation therapy (using high-dose x-rays to kill the cancer cells); biological therapy (using the body’s natural immune system to fight the cancer); and chemotherapy (using drugs to kill cancer cells).
Carcinoid tumors are considered a type of endocrine tumor since they secrete a hormone (serotonin). They can occur as part of certain genetic disorders such as the multiple endocrine neoplasia (MEN) type 1 and neurofibromatosis type 1 (NF1 or von Recklinghausen disease).
Arginine: An essential amino acid and a key component of protein. Lack of arginine in the diet impairs growth, and in adult males it decreases the sperm count. Arginine is available in turkey, chicken, and other meats, and as L-arginine in supplements. Babies born without the enzyme phosphate synthetase have arginine deficiency syndrome; adding arginine […]
- Argon laser
Argon laser: A laser with ionized argon as the active medium. Argon lasers are used for photocoagulation in ophthalmology.
Argyria: Silver poisoning, resulting in ashen, gray, discolored skin, and damage to other tissues of the body. Caused by long-term use of silver salts or other preparations containing silver.
Arhythmia: We do not usually give a misspelling but this is a frequent misspelling of arrhythmia (with two r’s), meaning an abnormal heart rhythm. In an arrhythmia the heartbeats may be too slow, too rapid, too irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than […]
Arimidex: Brand name for anastrozole, an oral antiestrogen. Arimidex inhibits the enzyme aromatase in the adrenal glands that produces the estrogens (estradiol and estrone) and thereby lowers their levels. It works by decreasing the amount of estrogen the body makes. This can slow or stop the growth of many types of breast cancer cells that […]