Selective protection of cells against X-irradiation. Isoproterenol protects only those cells that possesβ-adrenoreceptors

Summary In mixed culture of Chinese hamster fibroblatst, clone 431, and transformed murine L fibroblasts, clone B-82, isoproterenol was found to protect only 431 cells against ionizing radiation. It was shown that 431 cells, in contrast to B-82 cells, possess-adrenoreceptors, and the radioprotective effect of isoproterenol can be realized only if this agent interacts with-adrenoreceptors coupled with the cAMP system. Since malignization often causes the disappearance of-adrenergic and other hormone receptors, the combined culturing and irradiation of the cells studied can be regarded as a model of the growth of malignant cells (B-82) among normal tissue cells (431 cells) under conditions of radiation therapy. A possibility of selective protection against radiation damage of normal tissue cells, with retention of the former radiosensitivity of tumor cells, is discussed.     

AnAnolis skin melanophore assay suitable for photoaffinity labeling studies with α-MSH

Summary Visual determination of MSH-induced pigment migration in melanophores of small pieces ofAnolis carolinensis skin is standardized by first measuring photoelectrometrically the change in reflection/transmission of the whole dorsal skin in response to different hormone concentrations. This method allows the rapid and precise recording of time-response curves after photoaffinity labeling of MSH receptors or of dose-response curves of large series of synthetic compounds.Acknowledgments. We wish to thank Ms V. Jäggin, Ms C. Schulthess and Ms G. van Hees for excellent technical assistance, Dr. R. Andreatta, Ciba-Geigy AG, Basel, for his generous gift of -MSH and Prof. A Pletscher for his continuous interest. This work was supported by the Swiss National Science Foundation.     

Bicuculline and picrotoxin block γ-aminobutryic acid-gated Cl− conductance by different mechanisms

Summary Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for -aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused.To whom reprint requests should be addressed.Acknowledgments. We thank Drs S. Minakami and S. Yasui for helpful discussions and comments.     

The susceptibility to exercise-induced muscle damage increases as rats grow larger

Summary Glucose-6-phosphate dehydrogenase and N-acetyl--glucosaminidase activities were both elevated after eccentric exercise indicating that this type of exercise causes muscle damage. Muscle damage as measured by glucose-6-phosphate dehydrogenase activity in the vastus intermedius was greater and occurred later in larger rats indicating that the susceptibility to muscle damage is increased and the repair process delayed in older and larger animals.     

Quantitative genetic models of sexual selection

Summary Quantitative genetic models of sexual selection have disporven some of the central tenets of both the handicap mechanism and the sexy son hypothesis. These results suggest that the good genes approach to sexual selection may generally lead to erroneous results.Runaway sexual selection seems possible under a wide variety of circumstances. Quantittive genetic models have revealed runaway processes for sexually selected attributes expressed in both sexes and for attributes of parental care. Furthermore, the runaway could occur simultaneously in a series of populations that straddle an environmental gradient. While the models support the feasibility of runaway processes, empirical studies are needed to evaluate whether runaways actually happen. Estimates of critical genetic parameters are particularly needed, as well as measures of natural and sexual selection acting on the same population.The models also show that sexual selection has tremendous potential to produce population differentiation, particularly in epigamic traits. Differentiation is promoted by indeterminancy of evolutionary outcome, transient differences among populations during the final slow approach to equilibrium, sampling drift among equilibrium populations, and the tendency of sexual selection to amplify geographic variation arising from spatial differences in natural selection. Recent work with two- and three-locus models of sexual selection has produced results that parallel the results of the polygenic models^36–38,58. Thus the feature of indeterminate equilibria (outcome dependent on initial conditions) is common to both types of model.     

A new semisynthetic ergot peptide alkaloid: DCN 203-922

Summary We report the synthesis, stereochemistry and preliminary pharmacological evaluation of DCN 203-922, a novel ergot alkaloid of the cyclol type, which contains in its peptide moiety the uncommon amino acid L-allo-isoleucine.Part of this paper was reported by this author at the Herbstversammlung der Schweizerischen Chemischen Gesellschaft, Bern, in October 1986.     

A major metabolite of Δ1-tetrahydrocannabinol reduces its cataleptic effect in mice

Summary The results described here demonstrate that THC-induced catalepsy in mice can be substantially inhibited by the prior administration of ¹-THC-7-oic acid, the major metabolite of THC in most species including humans. This raises the possibility that the intensity and duration of action of THC may depend to a large degree on the levels of this metabolite at the sites of action.We thank the National Institute on Drug Abuse for supporting this project by grants DA-02043 and DA-02052 and for supplying all of the cannabinoids. One of us (S.B.) is also the recipient of a Research Scientist Award from NIDA. We are grateful to Kristen Carlson and Thomas Honeyman for helpful suggestions in preparing this report.     

震区中小跨径桥梁墩柱配筋率取值范围

为研究配筋率对钢筋混凝土桥梁延性抗震性能的影响,并在不同设防烈度对主筋配筋率的合理取值进行细分。以钢筋混凝土桥梁为研究对象,通过拟静力模型试验与有限元数值分析的方法,研究竖向钢筋(主筋)配筋率对桥墩延性的影响,提出典型桥墩的多级性能水平量化指标;并探究在氯离子侵蚀的恶劣环境下,不同配筋率对桥梁抗震性能所带来的影响,从而对氯离子侵蚀环境下的震区中小跨径桥梁墩柱配筋率取值范围提供参考建议。结果表明：考虑氯离子侵蚀作用下的恢复力模型能够较好地反映刚度的退化特性,墩柱的最佳配筋率取值范围为1.11%～2.72%;当加速度为0.3g(g为重力加速度)时,仅从配筋率的角度已无法满足墩柱的损伤指标,建议采用减隔震体系进行抗震设计,如采用延性体系时配筋率不得小于2.64%。研究结果可为中小跨径连续桥梁抗震设计提供参考。