Category: L
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Lignin (lignocellulose)
Indigestible part of the cell wall of plants (a polymer of aromatic alcohols). It is included in measurement of dietary fibre, but not of non-starch polysaccharide. A tough, fibrous material found in older plant cell walls. A complex biopolymer comprising the bulk of woody plants. It consists of polysaccharides and polymer phenols. A complex indigestible…
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Lieberkiihn, crypts of
Glands lining the small intestine which secrete the intestinal juice.
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Levans
Polymers of fructose (the principal one is inulin) that occur in tubers and some grasses. Derivate of sucrose formed by some species of streptococci, resulting in large mucoid colonies on sucrose – serum-digest agar.
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Leucovorin
The synthetic (racemic) 5-formyl derivative of folic acid; more stable to oxidation than folic acid itself, and commonly used in pharmaceutical preparations. Also known as folinic acid. Folinic acid, the active form of folic acid in the body. It is used to treat anemia and as an antidote to protect normal cells from high doses…
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Leucopenia
Decrease in the number of leucocytes in the blood. A reduction in the number of leucocytes in the blood, usually as the result of a disease. A condition in which the number of leucocytes in the blood is greatly reduced by, say, anaemia or cancer. It is also a dangerous sign in severe septicaemia.
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Leucocytosis
Increase in the number of leucocytes in the blood. An increase in the numbers of leucocytes in the blood above the usual upper limit, in order to fight an infection. A condition in which the polymorphonuclear leucocytes in the blood are increased in number. It occurs in many different circumstances, and forms a valuable means…
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Lethal dose 50% (LD50)
An index of toxicity, the amount of the substance that kills 50% of the test population of experimental animals when administered as a single dose. The dose of a drag that will cause death. For example, an LD50 signifies a dose that will kill 50% of the test subjects, therapeutic index. The dose required to…
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Less-favoured areas
Lands that have low agricultural potential because of limited and uncertain rainfall, poor soils, steep slopes, or other biophysical constraints, as well as lands that may have high agricultural potential but have limited access to infrastructure and markets, low population density, or other socioeconomic constraints.
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Lecithin
Chemically lecithin is phosphatidyl choline; a phospholipid containing choline. Commercial lecithin is a mixture of phospholipids in which phosphatidyl choline predominates. A fatty substance (lipid) found in many foods (milk, egg yolk and some vegetables). Used as an emulsifier. A by-product of the refining process for soybean oil (deoiled lecithin from processed soybeans is composed…
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Lactulose
A disaccharide of galactose and fructose which does not occur naturally but is formed in heated or stored milk by isomerisation of lactose. Not hydrolysed by human digestive enzymes but fermented by intestinal bacteria to form lactic and pyruvic acids. Thought to promote the growth of Lactobacillus bifidus and so added to some infant formulae;…