Establishment of serum based medium essentially free of proteolytic activity for the culture of mouse pancreatic islets

Summary The present study demonstrates that a) serum based culture medium degrades¹²⁵I insulin; b) heat in-activation of serum (1 h, 56°C) inhibits its proteolytic activity leading to the recovery of more insulin secreted by islets cultured in the presence of high glucose concentration alone or with glucagon; c) aprotinin also favoured the accumulation of secreted insulin by protecting the hormone from a residual degradative capacity of the heat treated serum.This work was supported by a grant (No. 71 5 426-2) from the INSERM and by the CNRS.These results have been presented at the V International Congress of Endocrinology. Hamburg, July 18–24, 1976.Acknowledgments. We should like to thank Mrs E. Gammelgard and K. Christensen for their technical assistance.     

Preferential neurotoxicity of pentobarbital on nerve and glial cells in culture

Summary The effect of pentobarbital was studied in a mixed population of nerve and glial cells dissociated from brains of 7-day chick embryos and maintained in culture. Pentobarbital-Na was added in various concentrations ranging from 5×10^–5 M to 1×10^–3 M. The neuronal density was monitored by counting of neurons, neuronal identity was established by staining for Nissl Bodies and acetylcholinesterase. Over a culture period of 3 weeks, it was found that the barbiturate exerts a preferential dose-dependent cytotoxic effect on neurons.The expert technical assistance of Miss A. Wolf is appreciated. This work was supported by grant 6-74-27, INSERM (Physiologie et Pathologie du Développement Nerveux).     

Identification of calcium antagonist receptor binding sites using (3H)nitrendipine in bovine tracheal smooth muscle membranes

Summary (³H)Nitrendipine binding to the bovine tracheal muscle membrane at 25°C was rapid, saturable (B_max=14.8±3.9fmol/mg protein) and of high affinity (K_d=0.15±0.04 nM). The rank order of Ca²⁺ antagonists competing for airway (³H)nitrendipine binding was nitrendipine nisoldipine nifedipine » verapamil. Cromolyn, however, neither inhibited nor increased the binding.J.B.C. is a visiting associate professor at the NYMMC. We thank Ms. Pang-jang Chang for technical assistance. This work is supported by a grant (NSC 72-0412-BO10-R20) from the National Science Council, ROC. To whom reprint requests should be addressed: Allergic Disease Center, Creighton University School of Medicine, Omaha, Nebraska 68178.     

The effect of the phytoalexins,lubimin, (−)-maackiain,pinosylvin, and the related compounds dehydroloroglossol and hordatine M on human lymphoblastoid cell lines

Summary We have tested the effect of the phytoalexins lubimin, (–)-maackiain and pinosylvin and the related compounds dehydroloroglossol and hordatine M on the growth of the human lymphoblastoid cell lines Molt and Raji. (–)-maackiain, pinosylvin and dehydroloroglossol showed significant growth inhibitory action on the cells. Suppression of [³H] thymidine and [³H] leucine uptake was tested and noted in pinosylvin and dehydroloroglossol. The phytoalexins and related compounds are widespread in plants and provide a potential source of antineoplastic substances.We would like to acknowledge the assistance of J. Hux in preparing the phytoalexins and related compounds. This work was supported by a grant from National Health and Welfare Canada. Correspondence to Dr. L. Skinnider, Department of Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7M OWO.     

Accumulation of3H-dopamine by synaptic vesicles from rat striatum in an impermeant medium

Summary The accumulation of³H-dopamine by synaptic vesicles from rat striatum was significantly stabilized in a membrane impermeant medium. The characteristics of dopamine accumulation by striatal vesicles were quite similar to those reported for dopamine accumulation by a whole brain vesicle preparation in the same medium, and were siginificantly different from the characteristics previously reported for vesicular accumulation of norepinephrine.Acknowledgments. This work was supported by grant NS 18752 (NIH) of the United States Public Health Service. Reprint requests to J. A. R.     

Moderate cooling depresses the accumulation and the release of newly synthesized catecholamines in isolated canine saphenous veins

Moderate cooling (from 37 degrees to 24 degrees C) depressed the formation of 3H-dopamine and 3H-norepinephrine from 3H-tyrosine by isolated canine saphenous veins. Cooling reduced the evoked release of newly synthesized catecholamine to the same extent as that of stored norepinephrine. Hence the augmentation by cold of the contractile response to sympathetic nerve stimulation observed in earlier work is not accompanied by an augmented release of newly synthesized norepinephrine.     

Development of noradrenaline uptake in the human foetal heart

Summary The development of NA-uptake mechanisms in the human foetal heart start at the same time as the adrenergic terminals were visible. The highest³H-NA values in the human foetal heart were only 25–30% of those found in the mouse heart.Acknowledgment. The technical assistance of Miss Marjo Martonen is gratefully acknowledged. This investigation was supported by a grant from the National Research Council for Medical Science, Finland.     

Establishment of a cell line (XTC-2) from the South African clawed toad,Xenopus laevis

Résumé On décrit une méthode pour l'établissement d'une culture de cellules du crapaud a griffes sudafricain,Xenopus laevis, afin de l'infecter avec des arbovirus. Les cellules (XTC-2) ont subi une culture continue pendant 3 ans. Elles ont un nombre diploïde de chromosomes. Elles furent cultivées aux températures de 22°C et de 28°C dans un milieu de culture dilué de NCTC 109 avec 10% de sérum de veau foetal.

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We thank ProfessorD. S. Bertram, Director of the Department of Entomology at the School, for his continued interest; Mr.A. O. Langi for technical assistance and Dr.L. Hamilton, Middlesex Hospital Medical School, London, for supplying theXenopus tadpoles. We are especially grateful to the Wellcome Research Laboratories, Beckenham, for supplying medium NCTC 109, and to Mr.D. J. Richmond of the Laboratories for responding to our request for medium promptly and willingly. The work is supported in part by a grant from the Medical Research Council of Great Britain.     

Effects of Ag+ on frog skin: Interactions with oxytocin,amiloride and ouabain

Summary Different biological effects of Ag⁺ (10^–4 M) were found depending on its presence in the outer or the inner solution bathing the frog skin. A marked increase in the electrical conductance and an interference with the action of oxytocin and amiloride were found only when Ag⁺ was added to the outer solution. Results suggest that Ag⁺ affects several transport processes, in particular the permeability of the Na entry pathways.This work was supported by the Swiss National Science Foundation, grant No. 1.300.73. We thank Mrs A. Cergneux for skilful secretarial assistance.     

Small lymphocyte production and lymphoid cell proliferation in mouse bone marrow

Summary In mice given³H-thymidine systemically during temporary circulatory occlusion of one hind limb, comparison of the labeling of rapidly-renewing small lymphocytes in the tibial marrows demonstrated that these cells were locally produced. Labeling by³H-thymidine infusion revealed that many marrow large lymphoid cells, presumptive small lymphocyte progenitors, had a marked proliferative activity and rapid turnover which varied according to cell size, was maximal in young mice and declined with increasing age.This work was supported by a grant from the Medical Research Council of Canada. The technical assistance of Mrs E. D. Watson is acknowledged.     

Abnormal organization of ovarian follicles in the mutantl(1)su(f) mad-ts ofDrosophila melanogaster

Summary The morphology of ovarian follicles in the temperature-sensitive female-sterile mutantl(1)su(f) ^mad-ts has been studied by means of light and electron microscopy. As the follicle cells gradually degenerate at the restrictive temperature (29°C) the follicles become increasingly disorganized with respect to shape and polarity.Acknowledgments. This work was supported by the Deutsche Forschungsgemeinschaft (SFB 46). We wish to thank Mrs R. Koppa for excellent technical assistance and Mrs G. Mahlke for photographic work. We are also indebted to Dr D. Zissler, Dr E. Gateff and Prof. K. Sander for many helpful suggestions.     

The role of sialic acid in 5-HT binding to synaptic membranes

Summary The high affinity binding of [¹⁴C]5-HT to nerve ending membranes isolated from rat brain is not affected by neuraminidase treatment. The specificity of ligand receptor interaction was demonstrated by displacement studies with tryptamine derivatives, noradrenaline, and acetylcholine.The expert technical assistance of Miss Christiane von Winterfeld is appreciated. This work was supported by a grant of the Deutsche Forschungsgemeinschaft.     

Effects of sphingolipids on erythroblastic maturation in the mouse

Summary The changes effected by injection of an extract of phospholipids obtained from the plasma of normal human donors (PLE) or an emulsion of commercially available sphingolipids on erythropoiesis in the mouse were studied. The parameters followed were⁵⁹Fe uptake by the erythroid tissue and the number of circulating reticulocytes. It was found that in the 12–24-h period following administration of PLE or purified sphingomyelin a significant increase in⁵⁹Fe uptake by circulating RBC and by their hemic fraction takes place. This change was associated with a higher⁵⁹Fe utilization by the bone marrow and with an increase in the number of circulating reticulocytes.Acknowledgments. This work was supported by a grant from the Consejo Nacional de Investigaciones científícas y Técnicas de la República Argentina. We thank Isabel Zingariello and Maria Amalia Nicastro for excellent technical assistance.     

Temperature dependence of neurotransmitter release in the antarctic fishPagothenia borchgrevinki

Summary The quantal contents of endplate potentials from extraocular muscles of an antarctic fishPagothenia borchgrevinki were measured over a range of temperatures. Quantal release was maximal at about 5°C but showed little dependence on temperature between –2°C and 10°C. Above 10°C quantal content declined until release ceased about 18°C. In view of the fact that the ambient temperature at which these fish live is constant at –1.9°C, the results suggest thatPagothenia borchgrevinki is only partially adapted to its environment despite 25 million years acclimatization.The authors wish to thank the staff of New Zealand's Scott Base, Antarctica, without whose cooperation the work would have been impossible. Mr J. Quinn of the Auckland University Physiology Department gave invaluable assistance with computing and electronics and the Antarctic Division of the New Zealand Department of Scientific and Industrial Research provided transportation and logistic support. The project was financially supported by the New Zealand University Grants Committee and the Auckland University Research Committee. S.P. was a Senior Fellow of the N.Z. Medical Research Council.     

Metabolic studies of Hg-203 onChlamydomonas reinhardi

Summary Sterile cultures ofChlamydomonas reinhardi, WT⁺, were treated with Hg-203 at 25°C to identify probably formed volatile mercury compounds. Experiments were performed with living and dead cells under aerobic or anaerobic conditions, respectively, and the mercury concentration was measured in the system algae/nutrient medium. We found a timerelated decrease of mercury concentration in the cell suspension and the cell-free nutrient medium due to a reduction of Hg⁺⁺ to Hg⁰, probably caused by extracellular enzymes; monomethyl or dimethyl mercury could not be detected.This work was supported by a grant of Österreichisches Bundesministerium für Gesundheit und Umweltschutz.     

The effects of triaminopyrimidine on the short circuit current and transmembrane potentials of the isolated rat visceral yolk sac in vitro

Summary Intracellular potentials in the cells from 17.5-day old rat visceral yolk sacs were measured by a glass microelectrode. When penetrated from the maternal side, the cells have potentials of about 50.2±1.9 mV (inside negative) which were reduced by increasing the external K⁺ concentration and increased by removing Na⁺ ions from the bathing fluid. Triaminopyrimidine (TAP) which inhibited Na⁺ transport caused a dose-dependent depolarization of the cell membrane. The depolarization was dependent on the presence of extracellular Ca²⁺ ions. It is proposed that TAP may inhibit Na⁺ transport by increasing the intracellular concentration of calcium ions.This work was supported by the University of Hong Kong (grant number 335. 034.5105).Acknowledgment. Triaminopyrimidine was synthesized by Dr. Barbara Roth of the Wellcome Research Laboratories.     

Nuclear localization of aldosterone in rat brain cells assessed by autoradiography

Summary Autoradiographic studies with³H aldosterone demonstrate nuclear concentration of hormone in neurons of the hippocampus, septum, allocortical regionss and brain stem reticular formation and motor nuclei of cranial nerves and in the meninges. The results suggest that mineralocorticoids have wide ranging effects on different parts of the central nervous system.This work was supported by the Medical Research Council of Canada and by PHS grant NS09914. We thank Ms Brenda McClain for technical assistance.     

Cold tolerance of two Antarctic terrestrial arthropods

Summary Two Antarctic arthropods,Alaskozetes antarcticus (Acari) andCryptopygus antarcticus (Collembola) possess the ability to supercool to –30°C, but the realisation of this potential is dependent on starvation. The mite contains glycerol in a concentration of about 1% fresh weight.Acknowledgments. We thank the British Antarctic Survey, Cambridge and the Zoological Institute. University of Oslo for support and reasearch facilities, and the Natural Environment Research Council for a research grant (GR. 3/2797). We are grateful to Ms I. Tambs-Lyche for technical assistance.     

Synthesis,crystallization and properties of acetyl phenylalanyl lysine chloromethyl ketone: A potential inhibitor of serine proteases

Summary A procedure for the synthesis of acetyl phenylalanyl lysine chloromethyl ketone is described. The chloromethyl ketone derivative is a noncompetitive inhibitor of trypsin (K₁=5.9×10^–3 M).Acknowledgments. The authors are grateful to Dr Arthur L. Bacon for his constant support and encouragement. Special thanks are due to Dr William Kray for initiating this research project. We thank Mrs Juliette Barclay, Ms Earlene Spratling and Ms Ollivette Hill for their technical assistance in conducting some of the experiments. This investigation was supported by MBS grant RR8105 from the General Research Support Branch, Division of Research Resources, National Institutes of Health.     

Interaction of CDP-choline with synaptosomal transport of biogenic amines and their precursors in vitro and in vivo in the rat corpus striatum

Summary Added to a striatal synaptosomal homogenate of rat brain, CDP-choline 10^–4 M inhibits the uptake of norepinephrine (NE), dopamine (DA) and serotonin (5 HT) in a competitive fashion and enhances the uptake of tyrosine and tryptophan; administered to animals, CDP-choline (50 mg/kg/l h/i.v.) inhibits only the in vitro uptake of DA but enhances the uptake of precursors.This research was supported by CNRS grant (ERA No. 560) and Inserm grant (FRA 5).