Protein Metabolism In Tissues Research Articles

Structure and Metabolism of Connective Tissue Proteins

Structure and Metabolism of Connective Tissue Proteins

Corticosteroid-Induced Changes in Urea Metabolism in Patients with Hepatocellular Disease

Quantitative studies of urea metabolism have been made by a kinetic technique using 13 C urea in 8 patients with hepatocellular disease before and after a 13-day course of prednisolone. After treatment the mean plasma urea concentration was higher in every case, the increases varying between 4 and 22 mg per 100 ml ( P P > 0.05). It is inferred that the liver in patients with hepatocellular disease usually has the capacity to increase the synthetic rate of urea appreciably in response to an appropriate stimulus. The data can be adequately explained in terms of the known effects of corticosteroids on nitrogen metabolism including the catabolic effect of these drugs on protein metabolism in peripheral tissues. The results imply that corticosteroids increase the turnover of nonprotein nitrogenous compounds of small molecular weight, including ammonia, in patients with liver disease.

Effect of Lighting Regimen on the Diurnal Distribution of Amino Acids Between Blood Cells and Plasma of Chicks

BLOOD amino acids, fueled by dietary sources, are the materia prima for the protein synthetic processes of the body. Consequently, in studies of protein metabolism in various organs and tissues it is important that the interrelationships of the amino acids in the plasma carrier and the formed elements of the bloodstream be clarified (McMenamy et al., 1960). This becomes of even more importance because of known diurnal oscillations or rhythms of blood amino acids (Feigen et al., 1967; Squibb, 1966).The following report concerns 1) the effect of lighting regimen on blood cell/ plasma amino acid ratios; and 2) the effect on these ratios of the addition of four times the requirement of l-lysine to the diet 72 hours prior to the time blood samples were taken.METHODSAt time of hatch White Leghorn cockerels were assigned to two equal groups; one was housed in all-wire community cages in an…

Quantitative tissue of human malnutrition using scalp hair roots.

THERE is at present no adequate way of detecting or quantifying slight degrees of protein or protein/calorie deficiency. Yet such deficiencies may affect health: malnutrition is known to increase susceptibility to infection and interferes with normal development in children. We therefore set out to find a measure of protein deficiency which would be simple to use on humans in the field and more sensitive than measurement of hair shaft thickness1,2 or root diameter3 or serum protein concentrations4, which are subject to such influences as haemodilution. At best serum proteins provide an indirect measure of tissue protein metabolism. A more direct assay can be obtained from scalp hair roots which are easily accessible and are sensitive to systemic influences including drug toxicity5,6, poisoning7 and malnutrition8. Bradfield3,8,9 has demonstrated the potential value of morphological examination of hair roots in the evaluation of protein or protein/calorie deficiencies, but experienced observers are needed for this technique, which is subjective and only semi-quantitative. These studies were performed to evaluate a method which can provide accurate quantitative objective data which reflect both hair root size and partial tissue loss in a single numerical value.

EFFECT OF DIMETHYL SULFOXIDE ON ZINC65 UPTAKE, RESPIRATION, AND RNA AND PROTEIN METABOLISM IN BEAN (PHASEOLUS VULGARIS) TISSUES

The effect of dimethyl sulfoxide (DMSO) on zinc65 uptake, respiration, RNA, and protein metabolism in various tissues of two bean (Phaseolus vulgaris L.) cultivars showing differential growth responses to zinc has been studied. At a concentration of 1%, DMSO stimulated zinc uptake in excised roots, stem‐callus tissue, leaf disks, and enzymically isolated leaf cells, but did not significantly alter the uptake and incorporation of C14‐uracil into RNA and C14‐methionine into protein, although a slight inhibition was discernible in some tissues. At a higher concentration (10%) DMSO increased Zn65 uptake in excise roots incubated for 2 hr; however, at the same concentration, C14‐uracil and C14‐methionine uptake and incorporation were considerably inhibited in all the tissues. Oxygen uptake as measured with Warburg manometers was impaired, and the inhibition showed a time and concentration dependency. The fact that DMSO inhibited respiration and RNA and protein metabolism, while at the same concentration zinc uptake was increased, suggests that zinc uptake in beans is primarily a non‐metabolic process. The possible mechanisms of DMSO action are discussed in the light of its reported effects on membrane permeability and cell metabolism.

Effect of Dimethyl Sulfoxide on Zinc 65 Uptake, Respiration, and RNA and Protein Metabolism in Bean (Phaseolus vulgaris) Tissues

The effect of dimethyl sulfoxide (DMSO) on zinc65 uptake, respiration, RNA, and protein metabolism in various tissues of two bean (Phaseolus vulgaris L.) cultivars showing differential growth responses to zinc has been studied. At a concentration of 1%, DMSO stimulated zinc uptake in excised roots, stem-callus tissue, leaf disks, and enzymically isolated leaf cells, but did not significantly alter the uptake and incorporation of C14-uracil into RNA and C14-methionine into protein, although a slight inhibition was discernible in some tissues. At a higher concentration (10%) DMSO increased Zn65 uptake in excise roots incubated for 2 hr; however, at the same concentration, C14-uracil and C14-methionine uptake and incorporation were considerably inhibited in all the tissues. Oxygen uptake as measured with Warburg manometers was impaired, and the inhibition showed a time and concentration dependency. The fact that DMSO inhibited respiration and RNA and protein metabolism, while at the same concentration zinc uptake was increased, suggests that zinc uptake in beans is primarily a non-metabolic process. The possible mechanisms of DMSO action are discussed in the light of its reported effects on membrane permeability and cell metabolism.

75Se-selenomethionine in the study of protein and amino acid metabolism of adult rats.

SummaryThere is abundant evidence that selenomethionine is an analogue of methionine. We have utilized whole-body counting of 75Se after the administration of 75Se-selenomethionine to determine whether this technique might be used to evaluate overall changes in protein metabolism in animals fed different amounts of protein or methionine. Changes in overall body counts were not sensitive to changes in these dietary variables, but the excretion of 75Se was greatly affected by the selenium content of the diet. Thus, whole-body counting is apparently not a useful technique for following the metabolism of tissue proteins.

Determination of Optimal Dietary Protein Requirements of Young and Old Dogs

The purpose of these investigations was to determine the optimal nitrogen intake that would produce maximal filling of the protein reserve of the animal. Data were obtained which indicate that the present method of calculating protein maintenance requirements as 2 mg of nitrogen/basal kcal is considered to be endogenous nitrogen and may not adequately fill the “protein reserves” of the animal. Both young dogs (one-year-old) and old dogs (12 to 13 years of age) can be placed in nitrogen equilibrium and maintained with 0.2 to 0.6 g casein nitrogen/day/kg of body weight. Liver and muscle protein to DNA ratios reached maximal values in young dogs that were fed 0.4 g of casein nitrogen/day/kg of body weight, whereas the older animals required 0.6 g of nitrogen to obtain optimal filling of the protein reserves. Under these conditions, the dogs cannot be placed in positive nitrogen balance by feeding more dietary protein. Liver and muscle RNA to DNA values are closely correlated with changes in protein to DNA levels. When all dogs reached nitrogen equilibrium when fed 0.5 g of casein nitrogen/day/kg, higher cellular RNA concentrations and rate of incorporation of radioactive leucine into tissue protein were obtained in the liver and muscle of young adults as compared with the older animals. A kinetic model was developed which can be used to explain the change in tissue protein metabolism that is associated with variations in the intake of dietary nitrogen.

INTERMEDIARY METABOLISM OF AMINO ACIDS IN SOME TISSUE PROTEINS OF THE CAT.

AbstractThe biosynthesis of amino acids of the proteins of several organs has been studied in a growing cat with the aid of acetate-1-14C.Heavy incorporation of 14C was observed in glutamic acid, aspartic acid and alanine, less activity in serine, glycine, proline and eystine, no activity in phenylalanine, tyrosine, threonine, valine, leucine, isoleucine, lysine and histidine. This pattern is valid for all organs examined, with the exception of arginine, which is fairly active in the liver and inactive in the small intestine.The amino acids of the liver proteins are most active in the incorporation of the tracer from labeled acetate.The isotope distribution in glutamic acid and aspartic acid indicates that in the biosynthesis of these acids in the carnivorous cat the same pathways are followed as in omnivorous Mammals.

Studies on the metabolism of tissue proteins. III. The turnover of soluble proteins and elastin labelled with 14C proline and its relation to exposure to total-body x-irradiation.

SummaryRats were injected with proline-U-14C and exposed to total-body x-irradiation at various time-intervals thereafter. Proline was isolated from the soluble protein and elastin fractions of various organs and its specific activity determined. In most organs an increase in specific activity of proline of these two protein fractions was observed after irradiation. This was interpreted to mean either a lowered metabolic replacement or a loss of certain components from these protein fractions after irradiation. It is suggested that the decrease in specific activity observed in the spleen is correlated to changes in the cell-population in this organ after irradiation.

Studies on the metabolism of tissue proteins. II. Influence of x-irradiation and starvation on the metabolism of collagen.

Rats were injected with proline-U-C/sup 14/ and exposed to total-body x irradiation at various time-intervals thereafter. Proline and hydroxyproline were isolated from collagen of various organs as well as from sub-fractions of skin collagen and their specific activity determined. From the changes in specific activity of proline and hydroxyproline observed after exposure it is postulated that more metabolically-active collagen is degraded and that the conversion of soluble to insoluble collagen is partially inhibited after irradiation. (auth)

Studies on the Metabolism of Tissue Proteins

Studies on the Metabolism of Tissue Proteins