Inhibition of nitrite assimilation by uncouplers of phosphorylation

Summary Carbonyl cyanide m-chlorophenylhydrazone (CCCP) and pentachlorophenol (PCP), two powerful uncouplers of phosphorylation, specifically inhibit the assimilation of nitrite in the course of nitrate reduction. These results support our former conclusion that high-energy phosphate is involved in the metabolism of nitrite.     

Die Serumgruppen-Systeme Lp(a), Gm(a), Gc und Hp bei Cerebralsklerotikern

Zusammenfassung Im genetisch determinierten Lp(a)-System war die Häufigkeit von Lp(a+) bei 307 Cerebralsklerosefällen statistisch signifikant erhöht im Vergleich zur Lp(a+)-Häufigkeit der gleichen Population. In den Systemen Gm(a), Gc und Hp wurde dagegen keine Veränderung der Genotypenhäufigkeit infolge der arteriosklerotischen Erkrankung festgestellt.

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In the genetically determined Lp(a) system the frequency of Lp(a+) showed with 45.6 per cent a statistically significant raise in 307 patients with cerebral sclerosis compared with 38.7 per cent in normal population. The increase of Lp(a+) is almost exclusively confined to weakly positive precipitation and is discussed in connection with the often observed increase of -lipoprotein concentration in the serum of arteriosclerotic persons. As expected no changes of genotype frequency due to arteriosclerotic diseases has been stated in the Gm(a), Gc and Hp system.

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Herrn Medizinalrat Dr. Wieder, Ärztlicher Direktor des Bezirkskrankenhauses, sind wir für die Überlassung der Blutproben zu besonderem Dank verpflichtet.

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(Direktor: Obermedizinalrat Dr. med. K. Thomas)     

Tissue-specific sorting of the human LDL receptor in polarized epithelia of transgenic mice

The distribution of human low density lipoprotein (LDL) receptors was studied by immunofluorescence and immunoelectron microscopy in epithelial cells of transgenic mice that express high levels of receptors under control of the metallothionein-I promoter. In hepatocytes and intestinal epithelial cells, the receptors were confined to the basal and basolateral surfaces, respectively. Very few LDL receptors were present in coated pits or intracellular vesicles. In striking contrast, in the epithelium of the renal tubule the receptors were present on the apical (lumenal) surface where they appeared to be concentrated at the base of microvilli and were abundant in vesicles of the endocytic recycling pathway. Intravenously administered LDL colloidal gold conjugates bound to the receptors on hepatocyte microvilli and were slowly internalized, apparently through slow migration into coated pits. We conclude that (a) sorting of LDL receptors to the surface of different epithelial cells varies with each tissue; and (b) in addition to a signal for clustering in coated pits, the LDL receptor may contain a signal for retention in noncoated membrane that is manifest in hepatocytes and intestinal epithelial cells, but not in renal epithelial cells or cultured human fibroblasts.