| lactic acid level | <investigation> A test that measures the amount of lactic acid in the blood. (25 Jun 1999) |
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| lactic acid | A byproduct of carbohydrate metabolism (anaerobic metabolism). A lactic acid level may be measured in the bloodstream in conditions of metabolic acidosis. Lactic acid is an intermediate product of carbohydrate metabolism and is derived mainly from muscle cells and red blood cells. Exercise will normally raise lactic acid levels. Conditions of oxygen deprivation (for example shock, heart failure, lung disease) will trigger anaerobic metabolism within muscle tissue resulting in lactic acid build up in the tissues. Normal lactic acid levels are 4.5 to 19.8 mg/dl. (25 Jun 1999) |
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| lactic acid bacillus | A member of the genus Lactobacillus. (05 Mar 2000) |
| lactic acid bacteria | <microbiology> A group of Gram-positive, non-sporing bacteria which carry out a lactic acid fermentation of sugars. It includes species of Lactobacillus, Leuconostoc, Pediococcus and Streptococcus. See: lactic acid fermentation. (25 Jun 1999) |
| lactic acid dehydrogenase | <enzyme> An enzyme with 5 forms: LDH-1 is in the heart, its blood level can rise when heart muscle is damaged. Other forms can be found in the liver, brain, kidney, skeletal muscle and bone. A useful blood test in the evaluation of many disease processes, including heart attack, liver disease, muscular dystrophy and bone disease. (27 Sep 1997) |
| lactic acid fermentation | <biochemistry> A type of fermentation carried out by lactic acid bacteria in which sugar (for example lactose, glucose, pentose) are converted either entirely (or almost entirely) to lactic acid (homolactic fermentation) or to a mixture of lactic acid and other products (heterolactic fermentation). (09 Oct 1997) |
| lactic acid oxidative decarboxylase | A flavoprotein oxidoreductase catalyzing oxidation (with O2) of l-lactate to acetate plus CO2 and water. Synonym: lactic acid oxidative decarboxylase. (05 Mar 2000) |
| lactic | <physiology> Of or pertaining to milk; procured from sour milk or whey; as, lactic acid; lactic fermentation, etc. <biochemistry, physiology> Lactic acid, a sirupy, colourless fluid, soluble in water, with an intensely sour taste and strong acid reaction. There are at least three isomeric modifications all having the formula C3H6O3. Sarcolactic or paralactic acid occurs chiefly in dead muscle tissue, while ordinary lactic acid results from fermentation. The two acids are alike in having the same constitution (expressed by the name ethylidene lactic acid), but the latter is optically inactive, while sarcolactic acid rotates the plane of polarization to the right. The third acid, ethylene lactic acid, accompanies sarcolactic acid in the juice of flesh, and is optically inactive. Lactic ferment, an organised ferment (Bacterium lacticum or lactis), which produces lactic fermentation, decomposing the sugar of milk into carbonic and lactic acids, the latter, of which renders the milk sour, and precipitates the casein, thus giving rise to the so-called spontaneous coagulation of milk. Lactic fermentation. See Fermentation. Origin: L. Lac, lactis, milk: cf. F. Lactique. See Lacteal, and cf. Galactic. Source: Websters Dictionary (01 Mar 1998) |
| lactic acidemia | The presence of dextrorotatory lactic acid in the circulating blood. Synonym: lactacidemia. Origin: Lactic acid + G. Haima, blood (05 Mar 2000) |
| lactic acidosis | <biochemistry, physiology> Acidosis caused by accumulation of lactic acid more rapidly than it can be metabolised. It may occur spontaneously or in association with diseases such as diabetes mellitus, leukaemia, or liver failure. (25 Jun 1999) |
| lactic dehydrogenase | <enzyme> The enzyme that catalyses the formation and removal of lactate according to the equation: pyruvate + NADH = lactate NAD. <cell culture> The appearance of lactic dehydrogenase in the medium is often usedas an indication of cell death and the release of cytoplasmic constituents. Acronym: LDH (25 Jun 1999) |
| ACE level | <investigation> This is a blood test which measures the concentration of angiotensin-converting enzyme (ACE) in the bloodstream. Elevations in angiotensin-converting enzyme are seen sarcoidosis, histoplasmosis, alcoholic cirrhosis, asbestosis, berylliosis, diabetes, Hodgkin's disease, hyperthyroidism, amyloidosis, primary biliary cirrhosis, idiopathic pulmonary fibrosis, pulmonary embolism, scleroderma, silicosis, tuberculosis, Gaucher's disease and leprosy. The normal values are 18 to 67 U/ml over 20 years of age (people under 20 have higher levels). (15 Jan 1998) |
| acoustic reference level | The biological reference level for sound measurements. When the term decibel is used to indicate the noise level, a reference quantity is implied; this reference value is usually expressed as a sound pressure of 20 micronewtons per square meter. The reference level is referred to as 0 decibels, the baseline of the scale of noise level's; this baseline is considered the weakest sound that can be heard by a person with very good hearing in an extremely quiet location. Other equivalent reference level's still being used include 0.0002 microbar and 0.0002 dyne per square centimeter. (05 Mar 2000) |
| background level | The average amount of a substance present in the environment. Originally referring to naturally occurring phenomena. Used in toxic substance monitoring. (05 Dec 1998) |
| blood porphyrin level | A test which is used to measure red blood cell porphyrin levels. Porphyrins are pigments found in both animal and plant life. This test is useful in evaluating any number of porphyrin disorders (involving the various porphyrins) of red blood cells. Increased levels of coproporphyrins can indicate congenital erythropoietic porphyria or sideroblastic anaemia. Increased protoporphyrins may be seen in infection, thalassaemia, sideroblastic anaemia, iron deficient anaemia, increased erythropoiesis and lead poisoning. Increased uroporphyrins may indicate congenital erythropoietic porphyria or erythropoietic protoporphyria. (27 Sep 1997) |
| carbon dioxide blood level | A measure of the bicarbonate level in the blood based on a venipuncture specimen. The serum carbon dioxide is one of the normally reported values in the electrolytes profile. Lower levels of carbon dioxide indicate an acidosis. The normal level is 20 to 29 mEq/L. Lower than normal levels can indicate diabetic ketoacidosis, lactic acidosis, alcoholic ketoacidosis, kidney disease, renal failure, diarrhoea, Addison's disease, ethylene glycol poisoning or methanol poisoning. Greater than normal levels can be seen with excessive vomiting, hyperaldosteronism and Cushing's syndrome. (27 Sep 1997) |