Medical Conditions Terminology in Category L

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Lactose Synthase

An enzyme of the transferase class that catalyzes the transfer of galactose from UDPgalactose to glucose, forming lactose. The enzyme is a complex of the enzyme N-ACETYLLACTOSAMINE SYNTHASE and alpha-lactalbumin; the latter protein is present in lactating mammary gland cells where it alters the usual specificity of the former to make lactose synthesis the preferred reaction. (Dorland, 28th ed) EC 2.4.1.22.

Lactose Operon

The genetic unit consisting of three structural genes, an operator and a regulatory gene. The regulatory gene controls the synthesis of the three structural genes: BETA-GALACTOSIDASE and beta-galactoside permease (involved with the metabolism of lactose), and beta-thiogalactoside acetyltransferase.

Lactose Malabsorption

The disease state resulting from the absence of lactase enzyme in the musocal cells of the gastrointestinal tract, and therefore an inability to break down the disaccharide lactose in milk for absorption from the gastrointestinal tract. It is manifested by indigestion of a mild nature to severe diarrhea. It may be due to inborn defect genetically conditioned or may be acquired.

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Lactose Intolerance

The disease state resulting from the absence of lactase enzyme in the musocal cells of the gastrointestinal tract, and therefore an inability to break down the disaccharide lactose in milk for absorption from the gastrointestinal tract. It is manifested by indigestion of a mild nature to severe diarrhea. It may be due to inborn defect genetically conditioned or may be acquired.

Lactose Factors

Plasmids which determine the ability of a bacterium to ferment lactose.

Lactoneotetraosylceramide

Glycosphingolipids containing N-acetylglucosamine (paragloboside) or N-acetylgalactosamine (globoside). Globoside is the P antigen on erythrocytes and paragloboside is an intermediate in the biosynthesis of erythrocyte blood group ABH and P 1 glycosphingolipid antigens. The accumulation of globoside in tissue, due to a defect in hexosaminidases A and B, is the cause of Sandhoff disease.

Lactoglobulins

Globulins occurring in milk. (From Dorland, 28th ed)

Lactoferrin

An iron-binding protein in plasma and secretions (milk, mucus, bile), secreted by leukocytes. It is an important component of GRANULOCYTES. It is bacteriostatic, working by depriving bacteria of iron essential for growth.

Lactococcus lactis

A non-pathogenic lactococcus found in dairy products and responsible for the souring of milk.

Lactococcus

A genus of gram-positive, coccoid bacteria mainly isolated from milk and milk products. These bacteria are also found in plants and nonsterile frozen and dry foods. Previously thought to be a member of the genus STREPTOCOCCUS (group N), it is now recognized as a separate genus.