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1.
Summary Alpha-tocopherol inhibits human platelet aggregation induced by arachidonate sodium, collagen, epinephrine, adenosine diphosphate or thrombin — arachidonate sodium being the most susceptible. The second phase of the biphasic platelet aggregation induced by epinephrine or adenosine diphosphate is preferentially inhibited.This work was supported by the Medical Research Council of Canada, Quebec Medical Council, and a Fraser Scholarship, McGill University. I thank Drs.K. N. Drummond andS. O'Regan for their comments.  相似文献   

2.
Summary The thyroxine binding prealbumin was crystallized by ammonium sulphate, sodium sulphate, magnesium sulphate, sodium phosphate and potassium phosphate. The form of the orthorhombic crystals was dependent on pH.

Für Diskussionen über die Form der Kristalle sind wir Herrn Prof. Dr. E.Hellner und Herrn Dr. R.Allmann vom Mineralogischen Institut der Universität Marburg zu Dank verpflichtet.  相似文献   

3.
The d-enantiomers of amino acids have been thought to have relatively minor functions in biological processes. While l-amino acids clearly predominate in nature, d-amino acids are sometimes found in proteins that are not synthesized by ribosomes, and d-Ala and d-Glu are routinely found in the peptidoglycan cell wall of bacteria. Here, we review recent findings showing that d-amino acids have previously unappreciated regulatory roles in the bacterial kingdom. Many diverse bacterial phyla synthesize and release d-amino acids, including d-Met and d-Leu, which were not previously known to be made. These noncanonical d-amino acids regulate cell wall remodeling in stationary phase and cause biofilm dispersal in aging bacterial communities. Elucidating the mechanisms by which d-amino acids govern cell wall remodeling and biofilm disassembly will undoubtedly reveal new paradigms for understanding how extracytoplasmic processes are regulated as well as lead to development of novel therapeutics.  相似文献   

4.
Summary We determined the sodium, chloride, and protein content of sera on the one hand, and the same constituents in pleural, ascitic and cerebrospinal fluid on the other. We found the proportions of sodium and chlorine of serum and corresponding fluid to be identical with the proportions calculated according tovan Slyke's formula on the basis of the Donnan equilibrium. Consequently one cannot draw any diagnostic conclusions from the sodium or chlorine content of these fluids, as they depend solely on the sodium or chlorine content of the serum and the protein content of the serum and fluid.  相似文献   

5.
Résumé La teneur et la concentration de la prolactine dans le lobe antérieur de l'hypophyse ont été déterminées aux temps variés de l'oestrus chez la ratte. Dans l'aprèsmidi du jour du pro-oestrus, la teneur et la concentration dans la glande s'abaissent. Ce changement a été bloqué par le pentobarbitrate de sodium injecté par voie i.p. á 13.30 h au jour du pro-oestrus.

We are greatful to Drs.K. Kuretani, H. Nagasawa andR. Yanai, for allowing us to use the microdensitometer (Canalco, Model E) in the Pharmacology Division, The National Cancer Center Research Institute, Tokyo.  相似文献   

6.
Summary Laser diffraction patterns from crayfish abdominal mechanoreceptors have been observed and the corresponding sarcomere lengths calculated and then correlated with sensory nerve discharge frequencies.Our thanks are due to the Australian Research Grants Committee for provision of the lasers and camera, to Dr.K. S. Imrie for the design of the interfacing cards, to ProfessorP. Mason and ProfessorR. E. Aitchison for their encouragement and advice, and toI. Paterson andC. March for constructing the equipement.  相似文献   

7.
Conclusion The advent of the general theory of relativity was so entirely the work of just one person — Albert Einstein — that we cannot but wonder how long it would have taken without him for the connection between gravitation and spacetime curvature to be discovered. What would have happened if there were no Einstein? Few doubt that a theory much like special relativity would have emerged one way or another from the researchers of Lorentz, Poincaré and others. But where would the problem of relativizing gravitation have led? The saga told here shows how even the most conservative approach to relativizing gravitation theory still did lead out of Minkowski spacetime to connect gravitation to a curved spacetime. Unfortunately we still cannot know if this conclusion would have been drawn rapidly without Einstein's contribution. For what led Nordström to the gravitational field dependence of lengths and times was a very Einsteinian insistence on just the right version of the equality of inertial and gravitational mass. Unceasingly in Nordström's ear was the persistent and uncompromising voice of Einstein himself demanding that Nordström see the most distant consequences of his own theory.  相似文献   

8.
Summary The contribution of Bayes to statistical inference has been much discussed, whereas his evaluations of the beta probability integral have received little attention, and Price's improvements of these results have never been analysed in detail. It is the purpose of the present paper to redress this state of affairs and to show that the Bayes-Price approximation to the two-sided beta probability integral is considerably better than the normal approximation, which became popular under the influence of Laplace, although it had been stated by Price.The Bayes-Price results are obtained by approximating the skew beta density by a symmetric beta density times a factor tending to unity for n , the two functions having the same maximum and the same points of inflection. Since the symmetric beta density converges to the normal density, all the results of Laplace based on the normal distribution can be obtained as simple limits of the results of Bayes and Price. This fact was not observed either by Laplace or by Todhunter.  相似文献   

9.
On December 13, 1679Newton sent a letter toHooke on orbital motion for central forces, which contains a drawing showing an orbit for a constant value of the force. This letter is of great importance, because it reveals the state ofNewton's development of dynamics at that time. Since the first publication of this letter in 1929,Newton's method of constructing this orbit has remained a puzzle particularly because he apparently made a considerable error in the angle between successive apogees of this orbit. In fact, it is shown here thatNewton's implicitcomputation of this orbit is quite good, and that the error in the angle is due mainly toan error of drawing in joining two segments of the oribit, whichNewton related by areflection symmetry. In addition, in the letterNewton describes quite correctly the geometrical nature of orbits under the action of central forces (accelerations) which increase with decreasing distance from the center. An iterative computational method to evaluate orbits for central forces is described, which is based onNewton's mathematical development of the concept of curvature started in 1664. This method accounts very well for the orbit obtained byNewton for a constant central force, and it gives convergent results even for forces which diverge at the center, which are discussed correctly inNewton's letterwithout usingKepler's law of areas.Newton found the relation of this law to general central forces only after his correspondence withHooke. The curvature method leads to an equation of motion whichNewton could have solvedanalytically to find that motion on a conic section with a radial force directed towards a focus implies an inverse square force, and that motion on a logarithmic spiral implies an inverse cube force.  相似文献   

10.
Summary The ring-E opened dihydro derivatives of tomatidine and soladulcidine give the corresponding N-chloroamines with N-chlorosuccinimide. Treatment of these compounds with sodium methoxide yields the spiroaminoketal alkaloids, tomatidine and soladulcidine respectively, in high yields, probably via instable C=N-unsaturated intermediates which undergo spontaneous stereospecific cyclisation.

Solanum-Alkaloide. XIII. Mitteilung. XII. Mitteilung:K. Schreiber undH. Ripperger, Exper.16, 536 (1960).  相似文献   

11.
Summary Changes in water, sodium, and potassium excretion following administration of synthetic oxytocin (Syntocinon)—alone or in combination with acetazolamide— resemble the changes that occur after an equivalent dose of neurohypophysial extract containing oxytocin. Since the action of Syntocinon on water and sodium excretion is manifest when carbonic anhydrase in kidney tissue is fully inhibited by acetazolamide, it may be assumed that the mechanism whereby Syntocinon increases sodium excretion is independent of carbonic anhydrase. Oxytocin does not affect ultrafiltration in the glomeruli (Krause 4) and would therefore appear to modify the reabsorption or excretion process in the tubuli.  相似文献   

12.
Summary A method is described which allows separation of the protectin Anti A hel (Anti A HP from crude extracts of the protein gland ofHelix pomatia. A solution of the crude extract in 0.05M sodium phosphate buffer, pH 7.0, is applicated on a Sephadex G 200 column. The protectin is retained on the gel matrix, while the other components of the mixture are eluted. The protectin is eluted with a 0.5M solution of glucose in buffer, and is isolated by dialyzation against aqua dest. and lyophilization.

Frau R.John und Frau B.Hoffmann sind wir für die gewissenhafte Durchführung der experimentellen Arbeiten zu Dank verpflichtet.  相似文献   

13.
The mysteries of adaequare: A vindication of fermat   总被引:2,自引:0,他引:2  
  相似文献   

14.
Summary Using an assay for sulfoiduronate sulfatase based on the degradation of35S mucopolysaccharides in a cellfree system, two clonal populations have been demonstrated in fibroblasts of heterozygotes for Hunter's syndrome. The locus responsible for sulfoiduronate sulfatase deficiency in thisX-linked mucopolysaccharidosis is therefore subjected to dosage compensation in females.Acknowledgments. The technical assistance of Mr.Antonio De Falco and Mrs.Carmela Salzano is gratefully acknowledged. The authors are indebted to Dr.H. Kresse (Münster, BRD) for helpful suggestions.  相似文献   

15.
    
Summary Methyl poly--glutamate, either of thel ord series, can be saponified with 0.5N sodium hydroxyde in the presence of freshly precipitated copper-II-hydroxyde. It was observed that in this procedure not even partial racemisation takes place, while the average molecular weight of the optically pure acids is of the order 13,000.  相似文献   

16.
The uptake ofL-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations ofL-[3H] arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37°C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 ML-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found thatL-arginine was transported into synaptosomes by two uptake components — a high affinity component (3.5 M) and a low affinity component (100 M). These two components were similar to the Ly+ system because of their extreme sensitivity to inhibition byL-lysine andL-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids.  相似文献   

17.
Summary Among many other things, Carnot stated a principle and proved a theorem. In 1850, Clausius corrected Carnot's theory, modifying it according to Joule's principle. He might have considered a corollary of the theorem as the mathematical formulation of Carnot's principle. We challenge the corollary: it is based on hidden assumptions, nor is it true for all cycles. Clausius realized the corollary's lack of generality, but on different grounds. In 1854, he generalized the theorem, and gave an (other) expression to Carnot's principle. We analyze Clapeyron's account of Carnot's theory, Thomson's account of 1849 and some of Clausius belated comments on his 1850 paper, as well Clausius' paper of 1854. We hope that they shed light on the corollary's tacit hypotheses and on the meaning of Carnot's principle. It is our contention: Clausius took seriously a contemporary meaning of the principle, and looked for a condition of integrability that could express recovery of the initial conditions of the reservoirs. Furthermore, he seems to have had some prior knowledge of the form the expression of the principle should take. Actually, this was the theory's natural candidate.  相似文献   

18.
Résumé Chez le rat la prostaglandine E1 augmente la consommation d'oxygène et la teneur en potassium, tandis qu'elle abaisse la teneur en sodium dans le tissu rénal et hépatique. On y a observé une corrélation entre l'effet et la dose de PGE1 employée. Cependant dans les coupes du tissu hépathique, la PGE1 est restée sans action. A même dose la PGF2 a produit des effets comparables à ceux qu'on obtient avec la PGE1. Ces résultats indiqueraient que la réponse natriurétique à la PGE1 ne semble pas due à une inhibition de la pompe de sodium des cellules tubulaires, mais à une élévation du flux sanguin rénal.

The authors wish to express their sincere thanks to Dr.M. Cereijido for his valuable criticism of this work and to MissL. A. Vargas andMr. G. Jordan for their competent technical assistance.

This work was supported by a grant from the CONICET and CondesaAna Thyssen de Zichy.  相似文献   

19.
Summary Antiserum to bovine pancreatic polypeptide (BPP) has been used for immunofluorescent staining in the light microscope. With this technique it is possible to detect the presence of specific cells in monolayer culture from neonatal rat pancreas which contain BPP or a closely related peptide.This work was supported by a grant (No. 3.553.75) from the Fonds National Suisse de la Recherche Scientifique. We are very grateful to Dr.R. E. Chance, Eli Lilly, for his generous gift of BPP and anti-BPP serum. We are also very obliged to Dr.R. H. Unger for providing glucagon, to Dr.J. Rivier and Dr.R. Guillemin for somatostatin, to Dr.N. Yanaihara for secretin, to Dr.W. Gepts for gastrin and to Dr.A. J. Moody for GLI.  相似文献   

20.
Summary Addition of polyelectrolytes, in particular of the sodium salt of carboxymethylcellulose, makes it possible to obtain for the use in artificial kidneys dialyzing liquids which are in thermodynamic equilibrium with blood, both with respect to salts and water, or which even permit removal of water from the blood, as well as urea and related substances (the dialyzing liquid being at will hypertonic with respect to blood), the salt content of blood remaining in all these cases unaffected. These dialyzing liquids might be particularly useful for cases combined with oedema.

Vorgetragen am Kongress der «3o riunioni medico chirurgiche internazionali», Turin 1957; erste Mitteilung hierüber im VortragvonW. Kuhn am Staffmeeting des Bürgerspitals Basel am 2. Februar 1955.  相似文献   

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