Medications

Level 2 biosafety: A level of biosafety considered appropriate for agents that can cause human disease, but whose potential for transmission is limited. A biosafety level is a specific combination of work practices, safety equipment, and facilities w...

Level 1 biosafety - Medical

Level 1 biosafety: The lowest level of biosafety, a level that applies to agents that do not ordinarily cause human disease. A biosafety level is a specific combination of work practices, safety equipment, and facilities which are designed to minim...

Leukotriene - Medical

Leukotriene: One of a group of hormones that cause the symptoms of hay fever and asthma. Derived from arachidonic acid, the leukotrienes act by mediating immediate hypersensitivity. Leukotriene modifiers that prevent the production or action of leuko...

Leukoreduction - Medical

Leukoreduction: A process used to filter and remove white blood cells from whole blood before transfusion. The reason why white blood cells ( leukocytes) are removed from blood is because they provide no benefit to the recipient but can carry bacteri...

Leukoplakia - Medical

Leukoplakia: A white spot or patch on the mucous membranes in the mouth (for instance, inside the cheeks, on the gums or the tongue) that may become cancerous.Last Editorial Review: 4/27/2011 5:27:15 PM...

Leukomalacia, cystic periventricular - Medical

Leukomalacia, cystic periventricular: Softening of the white matter near the ventricles of the brain resulting in abnormal cysts. Cystic periventricular leukomalacia is a major problem in very premature infants. Treating the mother with a cortisone...

Leukoencephalopathy with vanishing white matter - Medical

Leukoencephalopathy with vanishing white matter: An inherited brain disease that occurs mainly in children. and follows a chronic progressive course with additional episodes of rapid deterioration following stress from febrile infection or minor head...

Leukodystrophy - Medical

Leukodystrophy: A disorder of the white matter of the brain, the part of the brain that contains myelinated nerve fibers. The white matter is white because it is the color of myelin, the insulation covering the nerve fibers. (The white matter is as o...

Leukocytosis - Medical

Leukocytosis: Increase in the number of white blood cells. Last Editorial Review: 4/27/2011 5:27:15 PM...

Leukocytes - Medical

Leukocytes: Cells that help the body fight infections and other diseases. Also called white blood cells (WBCs). Last Editorial Review: 3/26/1998 2:27:00 PM...

Leukocyte,eosinophilic - Medical

Leukocyte,eosinophilic: See: Eosinophil.Last Editorial Review: 6/19/2004 Eosinophil: A type of leukocyte ( white blood cell) with coarse round granules of uniform size within its cytoplasm and typically a bilobate (two-lobed) nucleus. Eosinophils ar...

Leukocyte, granular - Medical

Leukocyte, granular: A type of white blood cell filled with microscopic granules (tiny sacs) containing enzymes that digest microorganisms. Granular leukocytes -- they are better known as granulocytes -- are part of the innate immune system and h...

Leukocyte count - Medical

Leukocyte count: A white blood cell (WBC) count. Last Editorial Review: 4/27/2011 5:27:15 PM...

Leukocoria - Medical

Leukocoria: A white pupillary reflex. When one shines a bright light on the pupil, it normally appears red. In leukocoria, the light makes the pupil look white. This occurs with a number of eye diseases including congenital cataract and retinoblastom...

Leuko- - Medical

Leuko-: Prefix meaning white, as in leukocyte (white blood cell). Leuko- comes from the Greek "leukos" meaning white. Leuco- is an alternate spelling. Thus, a leukocyte = a leucocyte.Last Editorial Review: 4/27/2011 5:27:15 PM...

Leukemoid reaction - Medical

Leukemoid reaction: A benign condition in which the high number of white blood cells found in a blood test resembles the numbers seen in leukemia. For example, infectious mononucleosis can return blood-test results with a leukemoid reaction.Las...

Leukemic reticuloendotheliosis - Medical

Leukemic reticuloendotheliosis: See: Hairy cell leukemia. Last Editorial Review: 6/11/2004...

Leuk- - Medical

Leuk-: Prefix meaning white, as in leukemia. Leuk-and leuko-, the form used before a consonant, come from the Greek "leukos" meaning white.Last Editorial Review: 12/4/2003 Leukemia facts What is leukemia? What are the ty...

Leucovorin - Medical

Leucovorin: Folinic acid, the active form of folic acid in the body. Used as an antidote to protect normal cells from high doses of the anticancer drug methotrexate and to increase the antitumor effects of fluorouracil ( 5-FU) and tegafur-uracil. Als...

Leucine - Medical

Leucine: An amino acid, one of the 20 building blocks of protein. A dietary essential amino acid, leucine is needed for optimal growth in childhood. It is one of the three branched-chain amino acids. Symbol: Leu. Last Editorial Review: 4/12/2003 ...

Leucemia - Medical

Leucemia: A different spelling of leukemia, cancer of the blood cells. The growth and development of the blood cells are abnormal. Strictly speaking, leukemia should refer only to cancer of the white blood cells (the leukocytes) but in practice...

Leu - Medical

Leu: Leucine. See also: Amino acid symbols.Last Editorial Review: 3/30/2003 Leucine: An amino acid, one of the 20 building blocks of protein. A dietary essential amino acid, leucine is needed for optimal growth in childhood. It is one of the three b...

Letrozole - Medical

Letrozole: An oral antiestrogen. Letrozole inhibits the enzyme aromatase in the adrenal glands that produces the estrogens (estradiol and estrone) and thereby lowers their levels. The brand name of letrozole is Femara. See also: Aromatase inhibit...

Lethargy - Medical

Lethargy: 1. Abnormal drowsiness, stupor. 2. A state of indifference. From the Greek lethargia, drowsiness.Last Editorial Review: 4/27/2011 5:27:15 PM...

Lethal gene, zygotic - Medical

Lethal gene, zygotic: 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...

Lethal - Medical

Lethal: Deadly, fatal, capable of causing death, death-dealing. The word "lethal" comes from the Latin "letum" meaning "death or destruction."Last Editorial Review: 4/27/2011 5:27:15 PM...

Let down reflex - Medical

Let down reflex: An involuntary reflex during breastfeeding which causes the milk to flow freely.Last Editorial Review: 3/26/1998 2:27:00 PM...

Lesion - Medical

Lesion: Pronounced "lee-sion" with the emphasis on the "lee," a lesion can be almost any abnormality involving any tissue or organ due to any disease or any injury. There are, not surprisingly, many types of lesions. There are also a number of ...

Lesbianism - Medical

Lesbianism: Female homosexuality. Also called sapphism (after the lesbian poet Sappho).Last Editorial Review: 4/27/2011 5:27:15 PM...

Lesbian - Medical

Lesbian: Female homosexual. The name "lesbian" comes from the Greek island of Lesbos in the Aegian Sea where in antiquity the women were said to be homosexual. The poet Sappho who lived on Lesbos (circa 600 BC) was a lesbian in both ...