A bioassay procedure for the evaluation of the nutritional quality of the protein in foods is described. This method involves measurement of the protein efficiency ratio (grams gain per gram protein consumed) under standardized conditions. Male rats of the Wistar strain 20–23 days of age are fed ad libitum an otherwise adequate reference diet containing 10% protein supplied by a standard sample of casein. Foods to be assayed are added to the diet as the sole source of protein at the expense of the casein and corn starch to maintain a protein level of 10%. Protein efficiency ratios (P.E.R.'s) are calculated after 4 weeks and are adjusted to a constant value of 2.5 for casein. Although influenced by the age of rat and subject to certain inherent criticisms, determination of P.E.R. values was found to be a simpler method for evaluating protein quality than determination of net protein retention or net protein utilization and equally sensitive.
The influence of grain boundary conductivity and microstructure on the electrical properties of BaCe 0.85 Gd 0.15 O 32d have been examined. Grain sizes were varied by sintering at various temperatures. Impedance data were analyzed using the brick layer model, and some new consequences of this model are presented. The specific grain boundary conductivity exhibits an activation energy of ϳ0.7 eV, and for similar processing routes, is independent of grain size. An isotope effect was observed, indicating that protons (or deuterons) are the mobile species. TEM investigations showed the intergranular regions to be free of any glassy phase that could account for the differences in bulk and grain boundary properties. Single-crystal fibers, grown by a modified float zone process, were notably barium deficient, and exhibited a low conductivity, comparable to that of polycrystalline Ba 0.96 Ce 0.85 Gd 0.15 O 32d .
Human alpha, pi, and mu class glutathione S-transferases (GSH S-T) have been localized immunohistologically in a variety of organs. Alpha GSH S-T are found principally in hepatocytes, proximal convoluted tubules of kidney, the deep reticular layer of the adrenal gland, interstitial cells of the testis, and oxyntic cells of the stomach. The pi GSH S-T are present in relative abundance in ductular, as opposed to parenchymal cells in the liver, pancreas, salivary glands, and kidney. The presence of mu GSH S-T in the tissues of certain patients and its absence in the same tissues from other patients has been demonstrated. The pi GSH S-T seems to be most persistently and strongly expressed in tumors but alpha GSH S-T are also found in some neoplasms whereas the mu GSH S-T are occasionally present when the other two transferases are weak or absent.
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