Distribution of newly synthesized DT-diaphorase in rat liver

The distribution, synthesis transport, and glycosylation of rat-liver DT-diaphorase has been investigated. The enzyme could be isolated using specific antibodies, mainly from the soluble supernatant but also from microsomal vesicles, Golgi membrane, and mitochondria. 40% of the microsomal enzyme was located in the lumen or on the interior side of the membrane, the rest remaining as an integral non-extractable part of the membrane. Synthesis of DT-diaphorase takes place on both free and bound ribosomes, although it was found to be transported in a sequential manner from the rough to the smooth endoplasmic reticulum and also subsequently to the mitochondria. The rough and smooth microsomal DT-diaphorase contains covalently bound carbohydrate, but no sugar moiety could be detected bound to the cytoplasmic form of the enzyme.     

Stereological ultrastructural study of myocardial atrophy in hypokinesia

The myocardium of Wistar rats immobilized for 5, 15 and 30 days was examined by morphometry and stereological methods for evaluating the volumetric and surface density of myofibrils, mitochondria, T system, sarcoplasmic reticulum and for the measurement of the volumetric ratio of different ultrastructures to the density of myofibrils and the surface-volumetric ratio of the main organelles of the cardiomyocyte. Myocardial atrophy was shown to develop in the course of hypokinesia. The 30-day hypokinesia entailed changes in ultrastructural organization of cardiomyocytes, attesting to the tension of intracellular systems responsible for energy supply, of ionic membrane transport and the contractile apparatus.     

Effect of alpha-tocopherol on the physicochemical properties of liver cell membranes in adrenalectomized rats

The increased content of lipid peroxidation products in the liver and an associated increase in the microviscosity of lipid nuclear and microsomal liver cell membranes, as well as disturbed protein-lipid interaction in them have been determined 8 days after adrenalectomy. The addition of alpha-tocopherol into the diet (4 mg per day for 7 days after the operation) prevented the activation of lipid peroxidation and the disturbances of physico-chemical membrane properties and the decrease in the muscular working capacity in rats caused by adrenalectomy.     

Interleukin inhibition by a parasite proteinase inhibitor, taeniaestatin

A proteinase inhibitor, taeniaestatin, isolated from the larval stage of the cestode Taenia taeniaeformis inhibits endogenous IL 2 generation in murine lymphocytes and IL 1 induced proliferation of murine thymocytes in a dose-dependent manner. However, taeniaestatin does not inhibit exogenous IL 2-induced proliferation of an IL 2-dependent cell line at any dose tested. These data indicate that the lack of IL 2 generation may be due in part to inhibition of a crucial cell-associated proteinase subsequent to cellular activation, or the lack of an effective IL 2 signal for differentiation. Our results are novel findings concerning molecular pathways for parasite inhibition of host immune responses, and suggest that selected proteinase inhibitors may be useful in clinical situations in which IL 1 or IL 2 are elevated.     

Quantitative characteristics of nitroblue tetrazolium reduction by the neutrophils in experimental systemic candidiasis

The quantitative study of the reduction capacity of neutrophils with respect to nitro blue tetrazolium in experimental systemic candidiasis has revealed an increase in this capacity within 20 days of the infection. The reduction capacity has been found to depend not only on the degree of the contamination of the body with Candida cells, but also on the stage of the inflammatory process.     

Studies on the biochemical basis of the nutritional quality of tsetse fly diets

Batches of freeze-dried pig and cow blood, whose nutritional value to G. p. palpalis ranged from low to near optimum, were analysed for amino acid, triglyceride and cholesterol content. The results of the chemical analyses were compared with the nutritional quality parameters observed when each batch of blood was fed to G. p. palpalis in an attempt to establish a chemical basis for the nutritional quality of diets for Glossina. In general, those pig or cow blood diets that had a higher nutritional quality also had a significantly higher amino acid content than the suboptimal diets. There were significant differences between the triglyceride and cholesterol content of pig and cow blood, with pig blood having more triglyceride, but less cholesterol than bovine blood. There was no apparent correlation between the triglyceride and cholesterol content and the nutritional quality of blood.     

Characterization of calf liver glucosidase I and its inhibition by basic sugar analogs

Glucosidase I, the enzyme catalyzing the first step of N-linked oligosaccharide processing, has been purified from calf liver crude membranes [H. Hettkamp, G. Legler, and E. Bause, (1984) Eur. J. Biochem. 142, 85-90]. Binding experiments with concanavalin A-Sepharose suggest that glucosidase I is a glycoprotein with high-mannose carbohydrate chain(s). The enzyme has a subunit molecular mass of approximately 83 kDa and specifically hydrolyzes the terminal alpha-1,2-linked glucose residue from the natural Glc3-Man9-GlcNAc2 oligosaccharide. Studies with a variety of substrates modified in the aglycon moiety suggest that the Glc2 branch rather than the more distant domains of the substrate molecule are important for binding and hydrolysis. Glucosidase I does not require metal ions for activity and is strongly inhibited by 1-deoxynojirimycin (dNM) and its N-alkyl derivatives. Ki values range from 0.07 microM for N-methyl-dNM to 1.0 microM for dNM, measured at the pH-optimum of enzyme activity. The pH dependence of inhibition indicates that the cationic form of the inhibitors is the active species. Comparison of the Ki for N-decanoyl-dNM (approximately 70 microM) with that of N-decyl-dNM (approximately 0.4 microM) suggests that electrostatic interactions at the catalytic site of the enzyme are important for inhibitor binding. 1-Deoxymannojirimycin, previously assumed to be a specific mannosidase inhibitor, as well as its N-methyl and N-5-carboxypentyl derivatives, inhibit glucosidase I with Ki values around 190, 17, and 100 microM, respectively. This apparent lack of specificity shows that in vivo experiments on N-glycoprotein processing as well as the interpretation of results with these mannosidase inhibitors may give misleading results when these compounds are used in the millimolar range.