Dissociation of glucocorticoid effects of C-21 steroids at high concentrations in thymocytes

Summary A dissociation between inhibition of RNA synthesis and cell lysis was observed when thymocytes of adrenalectomized rats were incubated with high concentrations of pregn-4-ene-11-ol-3, 20-dione and pregna-1,4-diene-11-ol-3,20-dione. In contrast, no dissociation of these effects was found with the typical glucocorticoids cortisol and corticosterone, nor with their 1,4-diene analogs under the same conditions.Acknowledgments. This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina to the Instituto de Biologia y Medicina Experimental and the Programa de Regulación Hormonal y Metabólica as well as by financial help from the Secretaría de Ciencia y Tecnología.     

The effect of daily evening isoproterenol administration on reproductive organ growth in male rats treated neonatally with testosterone propionate

Summary Daily evening injections of isoproterenol extended the period of high pineal N-acetyltransferase activity and retarded the growth of testes, seminal vesicles and prostate in rats treated neonatally with testosterone propionate.The authors are grateful to Mrs Marie Svobodová for her skillful technical assistance.     

Antioxidant effects on prostaglandin synthesis in rabbit kidney medulla slices

Summary Sodium diethyldithiocarbamate, 2,6-di-tert-butylphenol and N,N-diphenyl-p-phenylenediamine inhibited the generation of medullary prostaglandin E, but 1,2-dimethoxyethane (OH scavenger) and 2,5-dimethylfuran (¹O₂ scavenger) stimulated basal prostaglandin E production 1.2–1.3-fold. These results suggest that the balance between formation and removal of cellular lipid peroxides sets a peroxide level that can regulate the rate of prostaglandin formation in cells.     

Survival and endogenous spleen colonies of irradiated mice after skin wounding and hydroxyurea treatment

Summary Wound trauma-induced survival from radiation may be related to increased mitosis in hematopoietic cells. This is supported by the cell cycle-dependent drug hydroxyurea, which 1. blocked survival of wounded mice injected 2 or 3 days after 900 rad and 2. reduced the number of endogenous CFU-s in wounded mice injected shortly before 700 rad.Supported by the Armed Forces Radiobiology Research Institute, Defense Nuclear Agency, under Research Work Unit MJ00018. Views presented in this paper are those of the authors; no endorsement by the Defense Nuclear Agency has been given or should be inferred.Research was conducted according to the principles enunciated in the Guide for the Care and Use of Laboratory Animals prepared by the Institute of Laboratory Research, National Research Council.     

Structure,biosynthesis and functions of glycoprotein glycans

Since the pioneering work on structure and function of heteroglycans compiled in the classical books edited by A. Gottschalk in 1972¹, there have been several promising developments in glycoconjugate research, as reviewed in this article.In Part 1, contributed by A. Kobata, current knowledge on heteroglycan structures is presented and representative examples taken from higher organisms are given. Part 2, written by J. F. G. Vliegenthart and J. P. Kamerling, covers the most important achievements in methodology: procedures to obtain pure glycans and to analyze their structures. Part 3, contributed by J. Paulson, is devoted to biosynthesis of glycans now describable as pathways since several of the glycosyltransferases have been isolated and analyzed for specificity. In Part 4, contributed by E. Buddecke, current knowledge on functional roles of glycans is presented. It will become apparent that the prerequisite for valid work either in biosynthetic or functional context depends on solid structural information. This is particularly true whenever glycosyltransferase reaction products are being analyzed, or glycans involved in biological functions are investigated. Although in past years, a great deal of important knowledge has been gathered by use of crude glycosidase or glycosyltransferase activities (a notable example is found in reference 2), one may now postulate that glycans implicated in biological reactions should be thoroughly analyzed.This review may familiarize newcomers with the field of glycoconjugate research with special emphasis on glycoprotein glycans. Glycolipids are not included in this article as they have recently been reviewed by S. I. Hakomori³. The reader is also referred to several excellent monographs^4,5 and the Proceedings of the Glycoconjugate Symposia held biannually^6–8.     

Insulin stimulation of glucose and amino acid transport in mouse fibroblasts with elevated membrane microviscosity

Summary Basal and insulin-stimulated transport of 2-deoxy glucose and of -aminoisobutyric acid in mouse 3T3 fibroblasts were modulated by increasing the lipid microviscosity of the cell plasma membrane. The kinetics indicate that the insulin effect is induced either by recruitment of new transport carriers or by reduction of the translocation activation energy.This investigation was supported by grant No.5-R01-CA-27471-02, awarded by the National Cancer Institute, Department of Health, Education and Welfare.     

Effect of free fatty acids and cholesterol in vitro on liver plasma membrane-bound enzymes

Summary The effect of cholesterol and fatty acid treatment in vitro was tested on rat liver plasma membrane-bound enzymes and lipid fluidity. The observed alterations of membrane fluidity affect both (Na⁺–K⁺)-ATPase and Mg²⁺-ATPase activities but not 5-nucleotidase; basal adenylate cyclase as well as its hormonal sensitivity were differentially affected by changes of membrane microenvironment.This investigation was partially supported by the Italian National Research Council.     

Cyclic AMP concentration in the rat's preoptic region

Summary In rats adapted to a 1212 h light-dark (LD) schedule, cyclic AMP concentration in the preoptic region showed a L minimum and D maximum. No significant fluctuations were observed in the parietal cortex.Supported by grant No. 79.01946.04 awarded by the National Research Council (CNR), Rome, Italy.     

Leydig cell andΔ 5-3β-hydroxysteroid dehydrogenase activity in the testis of toad (Bufo melanostictus) following cold exposuredehydrogenase activity in the testis of toad (Bufo melanostictus) following cold exposure

Summary Leydig cell nuclear area and ⁵-3-hydroxysteroid dehydrogenase activity were increased in the testis ofBufo melanostictus 2 days after a single short-term cold exposure. Both parameters returned to normal values 4 days later.