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 Homocysteine Main Article |  Glossary |  Homocysteine Index 

Homocysteine Glossary of Terms

The following are health and medical definitions of terms that appear in the Homocysteine article.

Alzheimer's disease: A progressive neurologic disease of the brain that leads to the irreversible loss of neurons and dementia . The clinical hallmarks of Alzheimer's disease are progressive impairment in memory, judgment, decision making, orientation to physical surroundings, and language. A working diagnosis of Alzheimer disease is usually made on the basis of the neurologic examination. A definitive diagnosis can be made only at autopsy. On a cellular level, Alzheimer's disease is characterized by unusual helical protein filaments in nerve cells (neurons) of the brain. These odd twisted filaments are called neurofibrillary tangles. On a functional level, there is degeneration of the cortical regions, especially the frontal and temporal lobes, of the brain.
See the entire definition of Alzheimer's disease

Amino acid: One of the 20 building blocks of protein . The sequence of amino acids in a protein and, hence, the function of that protein are determined by the genetic code in the DNA .
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Amino acids: The building blocks of polypeptides and proteins.

Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red.
See the entire definition of Artery

Atherosclerosis: A process of progressive thickening and hardening of the walls of medium-sized and large arteries as a result of fat deposits on their inner lining.
See the entire definition of Atherosclerosis

Blood clot: Blood that has been converted from a liquid to a solid state. Also called a thrombus .
See the entire definition of Blood clot

Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".

Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
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Cardiovascular: The circulatory system comprising the heart and blood vessels which carries nutrients and oxygen to the tissues of the body and removes carbon dioxide and other wastes from them.
See the entire definition of Cardiovascular

Cardiovascular disease: Disease affecting the heart or blood vessels.
See the entire definition of Cardiovascular disease

Cholesterol: The most common type of steroid in the body, cholesterol has gotten something of a bad name. However, cholesterol is a critically important molecule.
See the entire definition of Cholesterol

Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time.
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Circulation: The movement of fluid in a regular or circuitous course. Although the noun "circulation" does not necessarily refer to the circulation of the blood, for all practical purposes today it does. Heart failure is an example of a problem with the circulation.

Coronary artery disease: A major cause of illness and death, coronary artery disease (CAD) begins when hard cholesterol substances (plaques) are deposited within a coronary artery.
See the entire definition of Coronary artery disease

Cysteine: An amino acid, one of the 20 building blocks of protein. Cysteine can be synthesized by the body and is not essential to the diet. Its key chemical feature is a thiol group that contains sulfur. This thiol group can combine with the thiol group of another cysteine to form a disulfide bridge, which helps structural proteins and enzymes maintain their configuration. Two cysteine molecules linked by a disulfide bridge make up the amino acid cystine. The symbol for cysteine is Cys.

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Deep vein thrombosis: A blood clot ( thrombus ) in a deep vein in the thigh or leg. The clot can break off as an embolus and make its way to the lung, where it can cause respiratory distress and respiratory failure .
See the entire definition of Deep vein thrombosis

Developmental delay: Behind schedule in reaching milestones of early childhood development.

Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus . Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria).
See the entire definition of Diabetes

Embolism: The obstruction of a blood vessel by a foreign substance or a blood clot blocking the vessel. Something travels through the bloodstream, lodges in a vessel and plugs it.
See the entire definition of Embolism

Enzymes: Proteins that act as a catalysts in mediating and speeding a specific chemical reaction .
See the entire definition of Enzymes

Essential: 1. Something that cannot be done without.
2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid.
3. Idiopathic. As in essential hypertension. "Essential" is a hallowed term meaning "We don't know the cause."

FDA: The Food and Drug Administration, an agency within the U.S. Public Health Service, which is a part of the Department of Health and Human Services.
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Folate: Folic acid, one of the B vitamins that is a key factor in the synthesis (the making) of nucleic acid (DNA and RNA).
See the entire definition of Folate

Folic acid: One of the B vitamins that is a key factor in the synthesis (the making) of nucleic acid (DNA and RNA).
See the entire definition of Folic acid

Food and Drug Administration: The FDA, an agency within the U.S. Public Health Service, which is a part of the Department of Health and Human Services.
See the entire definition of Food and Drug Administration

Genetic: Having to do with genes and genetic information.

Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
See the entire definition of Heart

Heart disease: Any disorder that affects the heart. Sometimes the term "heart disease" is used narrowly and incorrectly as a synonym for coronary artery disease. Heart disease is synonymous with cardiac disease but not with cardiovascular disease which is any disease of the heart or blood vessels. Among the many types of heart disease, see, for example: Angina; Arrhythmia; Congenital heart disease; Coronary artery disease (CAD); Dilated cardiomyopathy; Heart attack (myocardial infarction); Heart failure; Hypertrophic cardiomyopathy; Mitral regurgitation; Mitral valve prolapse; and Pulmonary stenosis.

High blood pressure : Also known as hypertension, high blood pressure is, by definition, a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90.
See the entire definition of High blood pressure

Homocysteine : An amino acid produced by the body, usually as a byproduct of consuming meat. Homocysteine is made from another amino acid, methionine, and then in turn is converted into other amino acids.
See the entire definition of Homocysteine back to top

Homocystinuria: A genetic disease due to an enzyme deficiency. Among other events, there is a buildup of the amino acid homocystine. Progressive mental retardation is common in untreated cases. The finding of vascular disease and premature arteriosclerosis in persons with homocystinuria led to the theory that homocystine may be a factor in heart disease.
See the entire definition of Homocystinuria

Homozygous: Possessing two identical forms of a particular gene, one inherited from each parent.

Hypertension: High blood pressure , defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90.
See the entire definition of Hypertension

Incidence: The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain date.
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Intern: In medicine, a doctor who has completed medical school and is engaged in a year of additional training at a hospital before residency. An intern may, for example, be in pediatrics or medicine (internal medicine). The internship year is often quite rigorous.
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Kidney: One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary tract. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.


See the entire definition of Kidney

Lancet: A small pointed knife; a surgical instrument with a short, wide, sharp-pointed, two-edged blade; a little knife with a small point. Lancets are used today to prick the skin (a finger, foot, ear lobe, etc.) to obtain a small quantity of capillary blood for testing.
See the entire definition of Lancet

Liter: A metric measure of capacity that, by definition, is equal to the volume of a kilogram of water at 4 degrees centigrade and at standard atmospheric pressure of 760 millimeters of mercury.

  • Metric equivalents -- There are 1000 cubic centimeters or 1 cubic decimeter in 1 liter.
  • U.S. equivalent -- A liter is a little more than a quart (1.057 U.S. liquid quarts).

See the entire definition of Liter

Methionine: An amino acid, one of the 20 building blocks of protein. A dietary essential amino acid, methionine provides methyl groups and sulfur for normal metabolism. Symbol: Met.

Milligram: A unit of measurement of mass in the metric system equal to a thousandth of a gram. A gram is equal to the mass of one milliliter, one thousandth of a liter, of water at 4 degrees C.
See the entire definition of Milligram

Molecule: The smallest unit of a substance that can exist alone and retain the character of that substance.

MPH: Master of Public Health (a master's degree in this field of medicine).

Onset: In medicine, the first appearance of the signs or symptoms of an illness as, for example, the onset of rheumatoid arthritis . There is always an onset to a disease but never to the return to good health. The default setting is good health.
See the entire definition of Onset

Osteoporosis: Thinning of the bones with reduction in bone mass due to depletion of calcium and bone protein . Osteoporosis predisposes a person to fractures, which are often slow to heal and heal poorly. It is more common in older adults, particularly post-menopausal women; in patients on steroids; and in those who take steroidal drugs. Unchecked osteoporosis can lead to changes in posture , physical abnormality (particularly the form of hunched back known colloquially as " dowager's hump "), and decreased mobility.
See the entire definition of Osteoporosis

Peripheral: Situated away from the center, as opposed to centrally located.
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Peripheral vascular disease: A disease of blood vessels outside the heart. Peripheral vascular disease (PVD) affects the peripheral circulation , as opposed to the cardiac circulation. PVD comprises diseases of both peripheral arteries and peripheral veins. PVD is sometimes incorrectly used as a synonym for peripheral artery disease (PAD). Intermittent claudication due to inadequate blood flow to the leg is an example of peripheral artery disease (PAD) while varicose veins and spider veins are examples of peripheral vein disease.
See the entire definition of Peripheral vascular disease

Polymorphism: A variation in the DNA that is too common to be due merely to new mutation. A polymorphism must have a frequency of at least 1% in the population.
See the entire definition of Polymorphism

Proteins: Large molecules composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.
See the entire definition of Proteins

Pulmonary: Having to do with the lungs. (The word comes from the Latin pulmo for lung).

Risk factor: Something that increases a person's chances of developing a disease.

Saturated fat: A fat that is solid at room temperature and comes chiefly from animal food products. Some examples are butter, lard, meat fat, solid shortening, palm oil, and coconut oil. These fats tend to raise the level of cholesterol in the blood.

Strain: 1. An injury to a tendon or muscle resulting from overuse or trauma. 2. A hereditary tendency that originated from a common ancestor. 3. To exert maximum effort. 4. To filter.

Stroke : The sudden death of some brain cells due to a lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain. A stroke is also called a cerebrovascular accident or, for short, a CVA.
See the entire definition of Stroke

Thrombosis: The formation or presence of a blood clot in a blood vessel. The vessel may be any vein or artery as, for example, in a deep vein thrombosis or a coronary (artery) thrombosis. The clot itself is termed a thrombus. If the clot breaks loose and travels through the bloodstream, it is a thromboembolism. Thrombosis, thrombus, and the prefix thrombo- all come from the Greek thrombos meaning a lump or clump, or a curd or clot of milk. See entries also to: Cavernous sinus thrombosis; Renal vein thrombosis. And see: Deep Vein Thrombosis and Pulmonary Embolism.

Vascular: Relating to the blood vessels of the body. The blood vessels of the body, as a group, are referred to as the vascular system.
See the entire definition of Vascular

Vein: A blood vessel that carries blood low in oxygen content from the body back to the heart. The deoxygenated form of hemoglobin (deoxyhemoglobin) in venous blood makes it appear dark. Veins are part of the afferent wing of the circulatory system which returns blood to the heart.
See the entire definition of Vein

Vessel: A tube in the body that carries fluids: blood vessels or lymph vessels.

Vitamin B12: A vitamin important for the normal formation of red blood cells and the health of the nerve tissues. Undetected and untreated vitamin B12 deficiency can lead to anemia and permanent nerve and brain damage.
See the entire definition of Vitamin B12

Vitamin B6: A group of closely related chemical compounds with related names -- pyridoxine, pyridoxal and pyridoxamine -- that are transformed within the body to yet another form of vitamin B6, pyridoxal phosphate, that acts as a coenzyme. (A number of vitamins serve as coenzymes, substances that enhance the action of enzymes and thereby aid in catalyzing biochemical reactions.)
See the entire definition of Vitamin B6

Vitamins: The word "vitamin" was coined in 1911 by the Warsaw-born biochemist Casimir Funk (1884-1967). At the Lister Institute in London, Funk isolated a substance that prevented nerve inflammation (neuritis) in chickens raised on a diet deficient in that substance. He named the substance "vitamine" because he believed it was necessary to life and it was a chemical amine. The "e" at the end was later removed when it was recognized that vitamins need not be amines.
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 Homocysteine Main Article |  Glossary |  Homocysteine Index 




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