Effect of propylthiouracil on intestinal tumor formation by azoxymethane in rats

Summary Treatment with propylthiouracil (PTU) resulted in a significant decrease in azoxymethane-induced intestinal tumors, total concentration of fecal bile acid as well as the fecal neutral steroids, cholesterol and coprostanol. Thus, a hypothyroid state induced by PTU treatment may affect intestinal carcinogenesis in this animal model by lowering the concentration of fecal bile acids and neutral steroids.We would like to acknowledge the excellent technical assistance of Dale Miller, Kenneth Kohn, Mathew McGee and Michael McLaughlin. We also wish to thank Dr M. S. Pak for the histological work, and Ms Mary Acree and Ms Kathleen Smith for the excellent secretarial assistance. Supported by the Maltida R. Wilson Fund.     

Stochastic synchronization of circadian rhythms

Models of circadian genetic oscillators involving interlinked feedback processes in molecular level genetic networks in Drosophila melanogaster and Neurospora crassa are studied, and mechanisms whereby synchronization can arise in an assembly of cells are examined. The individual subcellular circadian oscillatory processes are stochastic in nature due to the small numbers of molecules that are involved, and are subject to large fluctuations. The authors investigate and present the simulations of the stochastic dynamics of ensembles of clock-regulating proteins in different nuclei that communicate via ancillary small molecules, environmental parameters, additive cellular noise, or through diffusive processes. The results show that the emergence of collective oscillations is a macroscopic observable which has its origins in the microscopic coupling between distinct cellular oscillators.     

Nature of inhibition of rat testicular alkaline phosphatase by isatin

Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1). That the inhibition is non-competitive as well as non-allosteric is evident from a) the hyperbolic curve relating inhibition as a function of inhibitor concentration; b) the small change in enthalpy, free energy and entropy; c) the number of isatin molecules associating with 1 molecule of the enzyme (n=1.29); and, d) the decrease in the values of both Km and Vmax in the presence of isatin.     

Effect of decreased dietary protein upon mammary gland growth in rats

Zusammenfassung Nachweis, dass der gesamte DNS-Gehalt in der Brustdrüse bei Tieren mit proteinfreier oder 5% iger Proteinnahrung im Vergleich zu der Kontroll-gruppe herabgesetzt ist. Wird Protein in der Nahrung um 10–20% erhöht, so bleiben DNS-Gehalt und Körperwachstum konstant.     

Effect of an inhibitor isolated from onion (Allium cepa Linn.) bulbs on the activity of some of the enzymes involved in starch biosynthesis

Zusammenfassung Aus Zwiebelknollen (Allium cepa Linn.) wurde ein Hemmstoff der Phosphoglukomutase isoliert.