Über die Wirkung von Sr-Ionen auf den Ca2+-Austausch am Meerschweinchenvorhof

Summary When CaCl₂ in Tyrode solution was replaced by SrCl₂,⁴⁵Ca efflux from guinea-pig auricles did not change significantly. In Na-free solution, however,⁴⁵Ca influx was reduced when, in addition to CaCl₂, SrCl₂ was present in the solution, suggesting an equivalent replacement of Ca by Sr at membrane sites.     

Effect of aluminium phosphate gel on whole-body retention of simultaneously administered226Ra,85Sr and47Ca in mice

Résumé L'administration presque simultanée d'un gel de phosphate d'alumine et de²²⁶RaCl₂ réduit de 800 fois l'absorption intestinale du²²⁶Ra chez la souris. La charge corporelle en⁸⁵Sr et⁴⁷Ca est réduite d'environ 10 resp. 3 fois.     

Ileal absorption of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) and disodium dichloromethylene diphosphonate (Cl2 MDP) in the chick

Résumé Une proportion non négligeable de disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) et de disodium dichloromethylenediphosphonate (Cl₂MDP) peut être absorbée au niveau de l'ileum de poulet. L'absorption du Cl₂MDP est significativement supérieure à celle de l'EHDP.

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Acknowledgements. We thank MissLinda Senior for her skillful technical assistance. This work has been supported by the Procter and Gambel Company, by the US National Institute of Health (Grant No. AM 07256) and by the Swiss National Research Fund (Grant No. 3.326.70 Sr). R. H. W. was supported, in part, by the John Simon Guggenheim Foundation.     

Prolonged survival of AKR mice following allogeneic bone marrow transplantation

Zusammenfassung Die Mehrzahl der AKR Mäuse, die nach Immunosuppression und Transplantation von Knochenmark und lymphoiden Zellen allogener H₂-identischer Spender die «Graft-versus-Host» Reaktion überlebten, zeigten signifikant verlängerte mittlere Überlebenszeiten gegenüber Kontrolltieren, welche mit Immunosuppression allein oder Immunosuppression plus sygenen Zellen behandelt wurden.

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Supported by American Cancer Socitey Grant No. ET-55, a memorial to William Heller, Sr. and the Board of Trustees, Mount Sinai Medical Center.     

Excitation-contraction coupling in the myocardium of hibernating chipmunks

In the myocardium of nonhibernating chipmunks, replacing external Ca by Sr markedly prolongs the action potential plateau with an increase in contraction, while in preparations from hibernating animals this procedure inhibits both responses. Pretreatment with 4-aminopyridine causes a prolongation of the action potential plateau by Sr in hibernating animals.     

Periodicity in fish otolith Sr,Na, and K corresponds with visual banding

Examination of a section of an otolith from a teleost fish by fast atom bombardment-secondary ion mass spectrometry (FAB-SIMS) revealed seasonal periodicity in Sr, Na, and K concentrations that corresponded with visually observed annual banding. Strontium maxima also corresponded with Na and K minima and vice versa. In addition there was a general, apparently age-related, trend in Sr levels, with concentrations at the edge of the otolith being higher than in the core.     

双钙钛矿Sr2Mn1-xGaxMoO6（x=0．0～1．0）化合物的制备及其结构的研究

采用固相反应法制备了双钙钛矿Sr2Mn1-xGaxMoO6（x=0．0～1．0）掺杂化合物。室温下的高分辨率X射线衍射分析表明,Sr2MnMoO6具有单斜晶体结构,空间群为P21／n。Ga的掺杂没有改变化合物的晶体结构,但衍射峰整体向高角度漂移。结构精修分析表明,Sr2Mn1-xGaxMoO6样品的晶胞体积随Ga含量的增加而逐渐减小;B／B’位离子占位有序度伴随Ga的掺入而逐渐降低;此外,Ga的引入导致〈B—O〉键长的缩短,〈B’-O〉键长的伸长。     

Radiostrontium-Ausscheidung im Kot junger Ratten nach calciumreicher Ernährung

Summary Young immature rats of both sexes were fed with a diet either high (1.95%) or low (0.31%) in Ca content. A s.c. injection of weightless⁹⁰Sr results in a better excretion of radiostrontium with the faeces during feeding with high Ca diet. The retention of activity in the femori 30 days after injection is, in the same case, lower than by feeding with low Ca diet.     

Ein unterer Grenzwert für das Alter des Universums

Summary Measurements of the radiogenic⁸⁷Sr/⁸⁷Rb ratio of the chondritic meteorite Forest City are discussed in the light of a new determination of the half-life of⁸⁷Rb. Earlier conclusions are confirmed.     

The effect of dietary fibre on85Sr and47Ca absorption in infant rats

Summary The retention of bone-seeking radioisotopes⁸⁵Sr and⁴⁷Ca was about 20% lower in the femur of 6-day-old infant rats artificially fed on milk, milk supplemented with calcium and phosphorus, and milk supplemented with strontium when 6% cellulose type dietary fibre was added to the diet.Acknowledgments. This work was supported by a research grant from the Scientific Research Council of the Socialist Republic of Croatia. The authors wish to thank Mrs M. Buben, E. Herak, and K. Pribi for their technical assistance.     

Inhibition and enhancement of photically evoked responses by different doses ofl-DOPA

Summary Administration of small doses ofl-DOPA (10 and 20 mg/kg) resulted in reduction in amplitude of photically evoked responses in the primary visual, association, and cerebellar vermal cortices, while large doses (40 and 80 mg/kg) produced enhancement.Acknowledgment. We thank Prof.K. Kuriyama and Sr.M. McCormick for their help.     

Hydrogen peroxide generation inTrypanosoma cruzi

Summary Homogenates from T. cruzi epimastigotes produced 3.4 pmoles H₂O₂/min 10⁶ cells, as detected by the cytochrome c peroxidase assay. Addition of NADH or NADPH increased H₂O₂ production by a factor of 3 and 5, respectively. When supplemented with NADH and NADPH, the mitochondrial, microsomal, and supernatant fractions produced H₂O₂, the soluble fraction and the mitochondrial membranes being apparently the main generators of H₂O₂. The epimastigote homogenates showed cyanide-sensitive superoxide dismutase activity, equivalent to 0.28 g bovine superoxide dismutase per mg homogenate protein.This investigation was supported by grants from Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET) Argentina and the Scientific Office, American States Organization.Career Investigator of CONICET.     

Identification of a pre-hibernating state in myocardium from nonhibernating chipmunks

During the hibernating season, the amplitude of the cardiac action potential plateau of nonhibernating chipmunks was reduced. Replacing external Ca by Sr inhibited the electromechanical responses of these preparations. Similar properties were observed in hibernating animal preparations, suggesting that changes in cardiac function are already triggered before hibernation begins.     

Phosphocreatine and ATP concentrations increase during flow-stimulated metabolism in a non-contracting muscle

The gracilis muscle was excised from cold-acclimated rats, placed in vitro, and simultaneously perfused via its artery by high pO₂ medium and superfused by low pO₂ medium. With a doubling of the perfusion rate (from 50 to 100 μl/min) phosphocreatine and ATP increased by 39% and 44%, respectively.     

Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia

Summary Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N₂, 12% O₂ and 4% CO₂. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p<0.01) and a decrease in cyclic GMP (p<0.05) as compared to hearts perfused for 60 min with media gassed with 96% O₂, 4% CO₂.Acknowledgment. We gratefully acknowledge the excellent technical assistance provided by Mrs Inger O. Boggs and Miss Patricia C. Hannigan. This work was supported in part by U. S. Public Health Service grant HL 14661 from the National Heart and Lung Institute, and by a grant from the Central Ohio Heart Chapter.     

Specific immunosuppression of IgE response to hapten DNP by DNP linked to monoclonal IgG1 in rats

Summary The induction of the anti-DNP IgE in rat was suppressed by pretreatment of rats with the tolerogen synthesized by coupling DNP to rat IgG, i.e.; DNP_7–10-IgG. It was found that DNP₁₀-IgG₁ was an effective tolerogen, whereas other DNP conjugates, i.e. DNP₉-IgM, DNP₉-IgA, DNP₁₀-IgE, DNP₁₀-IgG_2c and DNP₁₀-IgG_2a were ineffective.This work was partly supported by a research grant from the Medical Council of Canada to W.Y.L.     

Plasma triiodothyronine,thyroxine and thyrotrophin levels in germfree rats

Summary Plasma T₃, T₄ and TSH levels in developing germfree rats were high, low and normal as compared with those in conventional counterparts. The high T₃/T₄ ratio in germfree rat plasma was lowered by cholestyramine feeding.This work was supported in part by a grant from the Imanaga Foundation, Nagoya, Japan.     

Identification of a pre-hibernating state in myocardium from nonhibernating chipmunks

Summary During the hibermating season, the amplitude of the cardiac action potential plateau of nonhibernating chipmunks was reduced. Replacing external Ca by Sr inhibited the electromechanical responses of these preparations. Similar properties were observed in hibernating animal preparations, suggesting that changes in cardiac function are already triggered before hibernation begins.15 December 1986     

A new interpretation of the sex determining mechanism of the European earwig,Forficula auricularia

Riassunto Osservazioni su femmine diForficula auricularia L. indicano che esse possiedono un solo cariotipo formato da 22 autosomi e da 2 cromosomiX. Sulla base di questo studio, suggeriamo che i maschi con 3 cromosomi sessuali sono del tipoXYY, e nonXXY come precedentemente ritenuto da varii autori. Ci sono maschiXY ₁t, XY₂, XY₂Y₂ e mosaiciXY ₂/XY₂Y₂ nella popolazione. Inoltre viene dimostrato che solamente il più grande dei due cromosomi Y, che caratterizzano questa specie, viene accumulato nei maschi con un meccanismo multiple di cromosomi sessuali.

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Supported by a postgraduate award from the Commonwealth of Australia to G.C.W. and by Public Health Service Grant No. GM-07212 from the Division of General Medical Sciences, U.S. National Institutes of Health and by a grant from the Australian Research Grants Committee.     

A marine mollusc provides the first example of in vivo storage of prostaglandins: Prostaglandin-1,15-lactones

Summary Prostaglandin-(PG) 1,15-lactones and, in smaller amounts, free acids, were isolated from both the mantle and the dorso-lateral appendices of the opisthobranch molluscTethys fimbria. In vivo conversion of PGs into the corresponding lactones and accumulation of PGE₂- and PGE₃-1,15-lactones in the appendages were shown. The detachment of these appendages from the molested mollusc caused the in vivo conversion of PGE₂- and PGE₃-lactones back to PGE₂ and PGE₃ respectively, thus providing the first example of a mechanism by which prostaglandins can be stored and, when needed, released.