Metabolism testing

Two simple metabolic tests may be used for evaluating infections by aerobic and anaerobic organisms. 

Chemistry0 Hematologic Tests0 Metabolic Tests" Tests Tests Tests Serum Electrolytes9 Dermatologic ... 

Pitfalls associated with metabolic screening are numerous. They can result from proximal tubulopathy, causing a reduction in blood lactate and an increase in urinary lactate from diabetes mellitus, hampering entry of pyruvate into the citric acid cycle from tissue-specific involvement or partial deficiency, which may barely alter the redox status in plasma. When metabolic tests are negative, respiratory chain deficiency may be misdiagnosed. 

Chemistry" Hematologic Tests" Metabolic Tests Tests Tests" Tests Serum Electrolytes Dermatologic ... 

As shown in Table 9.5, there are a number of indices of vitamin Be status available plasma concentrations of the vitamin, urinary excretion of 4-pyridoxic acid, activation of erythrocyte aminotransferases by pyridoxal phosphate added in vitro, and the ability to metabolize test doses of tryptophan and methionine. None is wholly satisfactory and where more than one index has been used in population studies, there is poor agreement between the different methods (Bender, 1989b Bates et al., 1999a). 

The tryptophan load test for vitamin Bg nutritional status (the ability to metabolize a test dose of tryptophan) is one of the oldest metabolic tests for functional vitamin nutritional status. It was developed as a result of observation of the excretion of an abnormal-colored compound, later identified as the tryptophan metabolite xanthurenic acid. 

Metabolic tests done early in the protocol to track the fate of the compound in the body. If metabolites are formed, their fates and toxicity must also be determined. Different species are used to test whether the metabolism is the same and to see which species will be most similar to humans. 

Moyer SR, Jurs PC. 1990. An SRA study of the mutagenicity of PAH compounds in Salmonella typhimurium. In Mendelsohn ML, Albertini J, eds. Progress in clinical and biological research Vol. 340. Mutation and the environment Part B. Metabolism, testing methods, and chromosomes. New York, NY Wiley-Liss, 1-10. 

USE To absorb carbon dioxide in basal metabolism tests, in rebreathing anesthesia systems, in submarines, and in carbon determinations. Caution Strongly corrosive and irri -tating to skin, mucous membranes, eyes. Ingestion can cause severe damage to G.l. tract, death. 

In severe disturbances of carbohydrate metabolism, test strip results for urine ketones can show varying degrees of positive results. Because the test strips are designed for testing human urine, the tester should be aware of some species differences (e.g., it is not uncommon to see slight ketonuria as detected by the test strips in rodent urine from control animals). The main constituents of the ketone bodies are 3-(3-hydroxybutyrate, acetone, and acetoacetate, and test strip results may be confirmed if necessary by measuring 3-(3-hydroxybutyrate (Laffel 1999). 

Space requirements and labor are reduced. One technician, with racks of tubes or cluster dishes can screen a few hundred compounds per week. Cell cultures are pipetted, simple metabolic tests can be used for assessment and many steps can -be automated. 

The toxicity of cyanogen chloride is attributed to its relatively easy decomposition to cyanide ion in an aqueous medium. The cyanide attacks the cells in the body and interferes with the cellular metabolism. Tests on rats indicated that exposure to cyanogen chloride caused lacrimation and chronic pulmonary edema and somnolence. At a high concentration of 300 ppm, death occurred to the test animals. Inhalation of 48 ppm for 30 minutes was fatal to humans. In animals, subcutaneous intakes of 5 and 15 mg/kg were lethal to both dogs and rabbits. 

Subchronic and chronic toxicological data (subchronic-toxicity tests, 3 months chronic-toxicity tests 2 years. Chronic-toxicity tests include carcinogenicity and reproduction tests (3 generations), residue dynamics, and metabolism and degradation data (metabolism tests in animals will be required after 1980)... 

Various criteria can be used to assess the viability or healthiness of brain slices. All are based on the view that the in vivo situation should be mimicked as closely as possible. Earlier studies employed metabolic tests, such as the ability to maintain high levels of energy-rich phosphates or to concentrate potassium from the bathing medium (Mcllwain and Rodnight, 1962 Frank, 1972). 

Analysis of hair samples—It is hoped that this test may serve at least as a screening method to identify people whose body stores of chromium are low because (1) the levels of the mineral in hair appear to parallel, roughly, the levels in other body tissues, and (2) extracts of hair have been found to act like the glucose tolerance factor (GTF). People whose hair levels of chromium are found to be low might then be given sugar and chromium metabolism tests. 

Since the hormone thyroxin constitutes the most important single factor influencing the rate of tissue oxidation, or basal metabolism, determination of the level of thyroid hormone in the bloodstream is used to detect the relative rate of basal metabolism. Good correlation with basal metabolism tests has been obtained by this method. 

The PBI test has largely replaced the measurement of oxygen consumption by respiration apparatus (1) because it is much simpler for both patient and technician, and (2) because many doctors feel that it is better suited to clinical purposes. However, the basal metabolism test is still the method of choice for nutritional studies. 

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