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Biomedical subjects

M L Scott

Publications and source records attributed to M L Scott.

At least 127 records · Page 7Linked to original sources
PubMed1976

Studies on the changes in reduced glutathione of chick tissues during onset and regression of nutritional muscular dystrophy.

Nutritional muscular dystrophy (NMD) in the chick results from a simultaneous deficiency of vitamin E and cystine. Muscle and liver of dystrophic and nondystrophic chicks were assayed for nonprotein sulfhydryl (NP-SH), reduced glutathione (GSH) and glutathione reductase. Red blood cells were assayed for NP-SH and GSH content. Glutathione peroxidase was determined in muscle, plasma and liver. Dystrophic muscle GSH was increased and at times was approximately double that of normal muscle, while liver GSH was lower in dystrophic than in normal chicks. During recovery from NMD, brought about by addition of either vitamin E or cystine to the dystrophogenic diet, muscle GSH declined and liver GSH increased to normal levels. Glutathione peroxidase was equivalent in both dystrophic and nondystrophic plasma and liver, but was significantly increased in dystrophic muscle. The mode of action of dietary cystine in preventing NMD in chicks remains unknown; it is not mediated through the role of amino acid as a component of the GSH needed for the action of glutathione peroxidase.

Animals↗
PubMed1976

Determination of antitrypsin activity on agar plates: relationship between antitrypsin and biological value of soybean for trout.

A new method is described for determination of antitrypsin activity based on inhibition of trypsin solubilization of calcium caseinate in agar plates. The method was applied to analyze soybeans after graded heat treatments for their antitrypsin content. Biological determination of protein and energy values of the soybean samples showed direct correlation of these values with the destruction of antitrypsin as measured by the new method, using rainbow trout.

Animals↗
PubMed1975

Flexible fiberoptic bronchoscopy with general anesthesia in the poor-risk patient.

A study is presented of seven poor-risk patients who had bronchoscopy with a flexible fiberoptic bronchoscope and balanced general anesthesia. The cardiorespiratory status, as evidenced by arterial blood gas determinations, electrocardiographic findings, and blood pressure measurements, was improved and stabilized in all patients. Flexible fibeoptic bronchoscopy, combined with general anesthesia, has proved to be a reliable and safe procedure useful for both diagnosis and treatment in poor-risk patients.

Adult↗
PubMed1975

Influence of dietary selenium on tissue selenium levels in turkeys.

To study the influence of dietary supplements of selenium on tissue selenium levels, duplicate groups of 20 Broad Breasted White turkeys were fed practical diets alone or supplemented with 0.1 and 0.2 p.p.m. Se as Na2SeO3. The concentration of naturally occurring selenium in the basal starting and finishing rations was 0.20 and 0.13 p.p.m. respectively. Selenium analyses were performed on samples of blood, liver, breast muscle and leg muscle obtained at 14 and 20 weeks of age. Supplemental selenium did not change the level of selenium in any of the tissues studied, nor did it affect weight gains. The concentration of selenium in blood and muscle was approximately 0.2 p.p.m. and ranged from 0.6 to 0.7 p.p.m. in liver. The results indicate that supplementing diets containing marginal levels of Se with 0.2 p.p.m. Se as Na2SeO3 does not lead to accumulation of Se in the tissues.

Administration, Oral↗
PubMed1975

Effects of PCBs, DDT, and mercury compounds upon egg production, hatchability and shell quality in chickens and Japanese quail.

Dietary polychlorinated biphenyls (PCBs), DDT and related compounds, in well controlled experiments, produced no detrimental effects upon egg shell quality in Single Comb White Leghorm chickens or in Japanese quail. PCBs caused some decrease in egg production and a drastic reduction in hatchability in chickens, but not in Japanese quail. Inorganic mercury as HgSO4 or HgCl2, at dietary levels up to 200 p.p.m. of Hg, had only small effects, if any, upon egg production, hatchability, shell quality, morbidity and mortality. However, methyl mercury chloride at levels which provided 10 or 20 mg. of Hg per kg. of diet caused severe effects upon egg weight, egg production, fertility, hatchability, egg shell strength, morbidity and mortality. The results of these experiments demonstrate that the decrease in egg shell quality which has occurred in eggs of White Leghorn hens over the past three decades is not due to contamination of commercial feeds with DDT or its derivatives, or with PCBs. The extent to which environmental contamination with methyl mercury is responsible for decreased egg shell strength in commercial laying hens, and possible synergistic relationships between methyl mercury, DDT, DDE and PCBs in reducing egg production, hatchability and shell strength, remain to be determined.

Adipose Tissue↗
PubMed1975

Effects of dietary polychlorinated biphenyls on vitamin E and selenium nutrition in the chick.

Experiments were conducted to determine the effects of polychlorinated biphenyls (PCBs) on vitamin E-selenium nutrition in the chick. Results showed that 10 p.p.m. Aroclor¿ 1254 in the diets of breeding S.C.W.L. hens increased the susceptibility of progency to vitamin E-selenium deficiency when those chicks were reared on a diet deficient in vitamin E and supplemented with a marginal level of selenium. Susceptibility to this deficiency, as measured by the incidence of exudative diathesis, was also increased when PCBs were added to chick diets. Dietary PCBs were shown to induce hepatic microsomal benzopyrene hydroxylase and induction of this activity was associated with decreased biological utilization of dietary selenium. PCBs were shown to increase the apparent requirements of the chick for vitamin E and selenium for prevention of exudative diathesis. However, discrimination between effects on vitamin E function and effects on selenium function was not possible in these experiments.

Animals↗
PubMed1975

Polychlorinated biphenyl-stimulated selenium deficiency in the chick.

Experiments were conducted to determine individually the effects of dietary PCBs on the physiologic functions of vitamin E and selenium. Results showed that dietary PCBs did not affect the function of vitamin E in protection of biological membranes. However, PCBs did decrease the biological utilization of dietary selenium as measured by glutathione peroxidase activity in plasma and by the protection of biological membranes from peroxidation. These results indicate that dietary PCBs potentiate vitamin E-selenium deficiency in the chick by interference with the biological utilization of dietary selenium. An hypothesis for the mechanism of this effect is offered.

Animals↗
PubMed1975

The effect of methionine deficiency on body weight, food and energy utilization in the chick.

The effect of dietary methionine deficiency was studied in broiler chicks. Graded levels of methionine: 0.25, 0.32, 0.39 and 0.46% in semipurified, soybean meal-corn starch diets were used as treatments. Food intake, body weights and body components were determined. Results show that a moderate methionine deficiency (0.32 and 0.39%) had no effect on growth and energy metabolism expressed as metabolizable energy, productive energy, heat production and tissue gains. Increased food intake in these two groups was reflected not as increased weight gain, but as greater quantities of tissue fat. The experimental group with severe methionine deficiency (0.25%) showed depressed body weight gain, food intake and efficiency of food utilization, with some increase in heat production. Therefore, in general, two types of nutritional responses occurred in broilers, based upon the severity of the methionine deficiency.

Animal Feed↗
PubMed1975

Mechanisms of action of selenium and vitamin E in protection of biological membranes.

Opinions vary as to the mode of action of vitamin E and selenium. Some argue that they act as nonspecific biological antioxidants. Others propose that the functions of the two substances are distinct and that vitamin E acts as a true vitamin in addition to functioning as a lipid-soluble antioxidant. Support for the "Biological Antioxidant Theory" is largely circumstantial. However, lipoperoxides have been detected in adipose tissues of vitamin E-deficient animals, and increased rates of in vitro peroxidation have been demonstrated in homogenates of several tissues of selenium and vitamin E-deficient animals. The basis of the antioxygenic role of selenium in these systems was elucidated by the discovery of Rotruck et al. (1973) that selenium is a component of rat erythrocyte glutathione peroxidase. Further studies in this laboratory have demonstrated the important role of glutathione peroxidase in protection against the vitamin E- and selenium-deficiency disease of chicks, exudative diathesis, which results from increased capillary permeability. Also shown were the activities of both dietary selenium and vitamin E in prevention of ascorbate-induced peroxidation in mitochondrial and microsomal preparations from chick liver. Recent results demonstrate that both selenium and vitamin E are required to protect hepatic mitochondria and microsomes from peroxidative degradation. Dietary requirements of the chick for both nutrients for this function have been determined: approximately 0.06 ppm selenium in the presence of adequate vitamin E; 30-50 IU vitamin E per kg in the presence of adequate selenium.

Aging↗