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Biomedical subjects

M L Scott

Publications and source records attributed to M L Scott.

At least 109 records · Page 6Linked to original sources
PubMed1981

Measurement of human serum IgE and IgA by reverse passive antiglobulin haemagglutination.

Serum IgE levels can be measured by reverse passive antiglobulin haemagglutination (RPAH) of trypsin-treated human or sheep red cells coupled to sheep IgG anti-human IgE by chromic chloride. The results show a high correlation with those obtained by the radioactive single radial immunodiffusion method. Interfering anti-sheep IgG factors can be easily removed by absorption with small amounts of whole sheep or bovine serum cross-linked with glutaraldehyde. Standardisation with the British standard for IgE shows that the detection limit of the RPAH method is 0.5 IU/ml (1.2 ng/ml). The system is therefore comparable in sensitivity to the paper radio-immunosorbent test, and has the advantages of being simple, rapid and cheap. The RPAH method can be used to measure any class of immunoglobulin. For IgA the detection limit is found to be 10(-4) IU/ml (1.4 ng/ml).

Absorption↗
PubMed1981

Comparison of red-cell linked anti-IgE and 125I-labelled anti-IgE in a solid-phase system for the measurement of IgE specific for castor bean allergen.

The report described the development of a mixed reverse (solid-phase) passive antiglobulin haemadsorption (MRsPAH) test for specific IgE antibody to castor bean allergen. The allergen is immobilised by formalin fixation in the wells of polyvinyl chloride microtitre plates. After allowing allergen-specific antibodies in the test serum to bind to the allergen, plates are washed thoroughly, and red cells coupled by chromic chloride to sheep IgG anti-human IgE are used to detect specifically bound IgE. This system was compared with a solid-phase radioimmunoassay in which 125I-labelled anti-IgE was substituted for the antiglobulin-linked red cells of the MRsPAH test; the earlier stages of both tests being the same. 12 sera, 10 from patients with allergic asthma to castor bean allergen and two from non-allergic controls, were tested for castor-bean-specific serum IgE by both methods and the results showed high correlation. The MRsPAH tst for allergen-specific serum IgE provides a useful alternative to the RAST system, being free of the disadvantages inherent in the use of radio-labelled materials.

Allergens↗
PubMed1980

Advances in our understanding of vitamin E.

Vitamin E is an essential nutrient for animals and man since it is not synthesized in the body. The level of vitamin E in the lipoproteins of plasma and in the phospholipids of vital mitochondria, microsomes, and plasma membranes in humans depends (as in experimental animals) on the amount of biologically active vitamin E being consumed, the levels of dietary prooxidants and antioxidants, and the adequacy of dietary selenium. Studies with chicks have demonstrated an important mode of action of both vitamin E and selenium in metabolism, and provide a solution to the long-term enigma of the true role of vitamin E in the diet of all animals, including man. The biochemical actions of vitamin E and selenium are concerned with prevention of peroxidative damage to cells and subcellular elements, thereby aiding the body in maintaining its normal defense mechanisms against disease and environmental insult.

Animals↗
PubMed1979

Influence of vitamin B-6 upon reproduction and upon plasma and egg cholesterol in chickens.

Vitamin B-6 deficiency in the laying hen causes an immediate anorexia, loss of body weight, greatly reduced body fat stores and severe effects upon primary and secondary sex characteristics resulting in severely reduced hatchability culminating in complete cessation of egg production. While inanition may have been largely responsible for involution of the ovaries and oviducts in the vitamin B-6 deficient hens, regression of combs and wattles appears to be a more specific sign of vitamin B-6 deficiency. Serum cholesterol levels of vitamin B-6-deficient hens were lower than those of hens receiving an adequate diet. Egg cholesterol values remained relatively constant regardless of dietary B-6 levels or of alterations in serum cholesterol. No ataxia or mortality was observed in vitamin B-6-deficient hens or roosters. The effects of vitamin B-6 deficiency were almost completely reversed upon repletion of the hens with adequate dietary vitamin B-6.

Animal Feed↗
PubMed1979

Effects of interstimulus interval on latency of the brainstem auditory evoked potential.

Peak latency of the inferior collicular response (wave V) of the brainstem auditory evoked potential (BAEP) increases with decreasing interstimulus interval (ISI). The present research investigated relative peak shifts of major components of the BAEP in an attempt to identify the source of the observed shift in wave V. Peripheral as well as central transmission times (CTT) were computed for 9 young adults between an ISI of 100 msec and an ISI of 10 msec. The results indicate that shifts in wave V latency with changing ISI are due to a combination of central and peripheral processes. The magnitude of the shift observed for wave V was approximately 0.50 msec. This increase in latency was accounted for by an average 0.29 msec increase in peripheral transmission time, a 0.14 msec increase in CTT between waves I and III, and a 0.07 msec increase in CTT between waves III and V. The results suggest a dual process underlying latency changes in wave V of the BAEP as a function of decreasing ISI. These are peripheral adaptation or fatigue and central processes that may include short-term habituation.

Acoustic Stimulation↗
PubMed1978

Heat increment associated with dietary protein, fat, carbohydrate and complete diets in salmonids: comparative energetic efficiency.

The heat increment (HI) of feeding, which is the increased heat production following consumption of food by an animal, accounts for as much as 30% of the ingested metabolizable energy (ME) in mammals and birds. The purpose of these experiments was to measure the HI associated with the feeding of a complete diet and purified fat, protein, and carbohydrate to salmonids. Measured amounts were fed and the heat production was measured by direct calorimetry. Increased heat production was observed about 30 minutes after feeding and remained elevated for 1 to 5 hours, depending on the amount and type of material fed. The HI of protein was much lower with fish than with mammals and amounted to less than 5% of the ingested ME. The HI's of carbohydrate and protein were not significantly different from each other but both were higher than fat. The HI, when complete diets were fed, was less than 3% of the ME. The net energy of protein is higher for fish than for birds or mammals. A major part of the superior energetic efficiency of fish is due to the low energy cost of protein metabolism.

Animals↗
PubMed1977

Oxidative deterioration of the muscle proteins during nutritional muscular dystrophy in chicks.

Nutritional muscular dystrophy in the chick results from the simultaneous deficiency of vitamin E and cystine. Being a biological antioxidant, vitamin E might be functional in maintaining a proper redox state of the sulfur-containing amino acid in the proteins. The analyses of protein-bound sulfhydryls and disulfides at onset of muscular dystrophy in young chicks were carried out. The ratio of disulfide to sulfhydryls increased two- to three-fold in dystrophic muscle as compared to that in the control muscle proteins. Dystrophic and normal muscle proteins also were subjected to SDS-gel electrophoresis. Proteins of low molecular weight, supposedly derived from proteolysis, were present in the gels of the dystrophic muscle and absent in those of normal muscle extracts. As a result of these studies, a chemical model has been proposed to explain the oxidative deterioration of proteins in nutritional muscular dystrophy due to vitamin E deficiency.

Amino Acids, Sulfur↗
PubMed1977

Changes of lipoamide dehydrogenase and mitochondrial structure in selenium-deficient chicks.

A selenium deficiency in chicks produces degeneration and fibrosis of the pancreas. An investigation was undertaken to determine whether or not the activity of lipoic acid is impaired in the pancreas of selenium-deficient chicks. Enzymatic analyses of selenium-deficient chick tissues showed a reduction in lipoamide dehydrogenase both in pancreas and liver at a very early stage of growth. Using both direct measurements and sucrose-gradient cellular fractionation, it was found that the lipoamide dehydrogenase activity of the supernatant increased, and that of the mitochondria decreased in selenium-deficient as compared to normal chick livers. These results indicate an increased fragility of the mitochondrial membranes in selenium-deficient chicks.

Animals↗
PubMed1977

Effects of PCBs, DDT, and mercury compounds in chickens and Japanese quail.

In well-controlled experiments using white leghorn chickens and Japanese quail, dietary polychlorinated biphenyls (PCBs), DDT and related compounds produced no detrimental effects on eggshell quality. A drastic reduction in hatchability of chicks occurred with 10-20 ppm PCBs, but no detrimental effects on eggshell quality, egg production or hatchability were found with 0.5 and 1.0 ppm PCBs, or DDT up to 100 ppm. Dietary PCBs potentiated a vitamin E-selenium deficiency in the chick, increased exudative diathesis, and decreased plasma glutathione peroxidase levels. Dietary PCBs induced hepatic microsomal benzopyrine hydroxylase. Dietary levles of 100 or 200 ppm inorganic mercury as HgSO4 or HgCl2 had little effect on egg production, hatchability, shell quality, morbidity and mortality. Methylmercury chloride, however, at levels providing 10 or 20 mg Hg/kg of diet, severely affected all of these parameters. Even though the present experiments demonstrate that neither DDT nor PCBs has any effect on eggshell quality in chickens and Japanese quail, they may cause thinning of eggshells in other species. Controlled experiments are lacking. Eagles, ospreys and pelicans all consume fish which in many areas of the world are known to contain methyl mercury. The thinning of eggshells in the species in the wild may have been due, at least in part, to environmental contamination with methylmercury rather than DDT, DDE or PCBs, as has been claimed.

Animals↗