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Summary The conversion of cholesterol into 19-nor-5-cholestan-3-ol by the spongeAxinella polypoides involves a partial loss (40%) of the 3-hydrogen atom; moreover administration to the sponge of [4-14C]cholesterol tritiated at C-4 and C-7 showed that the 4- and 7-hydrogen atoms are retained in this conversion. A competitive uptake experiment, [4-14C]cholesterol vs. [7-3H2]5-cholestanol, showed that the sponge utilized exclusively cholesterol for the production of 19-nor-5-cholestan-3-ol.Part of this work has been presented at the Nato Conference on Marine Natural Products (Jersey, Great Britain, October, 1976).-This contribution is part of the Programma finalizzato Oceanografia e Fondi marini-sottoprogetto Risorse biologiche C.N.R. Italy.  相似文献   

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a aaa a aa aa a a E. coli aa, a aa aa a , a a aa - a .

Laboratory of Biological Investigations.

Laboratory for Chemistry of Antibiotics.  相似文献   

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Summary Tritium-labelled PGF2 was administered i.v. into rats of varying ages (2, 4, 6 weeks and adult). Urine was collected and assayed for radioactive products by thin-layer-chromatography. Results showed a distinctly different urinary profile between the 2-week-old and the adult rat. While the urinary pattern from the 2-week-old rat gave a single less polar product than PGF2, the pattern from the adult rat gave products more polar than PGF2. Urine from the 4- and 6-week-old rats gave a mixture of these types of products. These results indicate that some prostaglandin catabolic pathway (likely the -oxidative system) is activated in vivo within the 4–6-week postnatal period in the rat.Supported by a grant (MT-4181) to C.P.-A. from the Medical Research Council of Canada.This study is in partial fulfillment of the requirements for a Ph.D. degree in the Department of Pharmacology, University of Toronto.  相似文献   

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Conclusion Geminus account of lunar motion in chapter 18 of hisIntroductio astronomiae is, in our view, an important contribution to Greco-Latin astronomy because, in attempting to reconstruct arithmetically (the parameters of) the Moon's motion in longitude, he undermines the task astronomers had hitherto set for themselves. This undermining of a commonly acknowledged view of the purpose of astronomy is articulated in a whole new set of questions concerning the nature and place of both observation and mathematical reasoning in the science of the heavens. Yet, one must not overlook the fact thatGeminus reconstruction also indicates resources for addressing these questions. Of these resources, the most powerful proved to be the idea that irregular motion could be quantified as a systematic departure from a mean motion, and the idea that observational data could be organized and structured by means of genetic arithmetical reconstructions.But, since we limit our attention to extant treatises and decline to speculate about works or parts of works that have not survived, we must say that it would takePtolemy to discern the new direction for astronomy thatGeminus opened up and to pursue it. In part, this involved straightening out the conflated conception of mean motion in chapter 18 — the qua arithmetic mean daily displacement can only be anapparent lunar motion in longitude and not one the Moonreally makes, but the same need not be true of the qua periodic mean daily displacement — and determining its proper relation to real and apparent planetary motion. Indeed,Ptolemy's genius lay, we think, in seeing that even though, in assimilating Babylonian astronomy, earlier and contemporary Greco-Latin writers betrayed a confused, inconsistent, and unsophisticated grasp of the proper role of arithmetic, geometry, and observation in astronomical argument [seeBowen 1994], the solution lay in a mathematical reconstruction of the observed celestial motions, in which mean motion played an essential role.  相似文献   

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Summary Some compounds containing piperidine rings have been synthesized, and submitted to biological tests on insects for their hormonal activity on pupae ofTenebrio molitor L. andBombyx mori L. Some of them display a hormoneanalogue or toxic activity.The editors do not hold themselves responsible for the opinions expressed in the authors' brief reports. — Les auteurs sont seuls responsables des opinions exprimées dans ces brèves communications. — Für die Kurzmitteilungen ist ausschliesslich der Autor verantwortlich. — Per le brevi comunicazioni è responsabile solo l'autore. — . — Solo los autores son responsables de las opiniones expresadas en estas comunicationes breves.This research has been supported by the Italian National Research Council (CNR) special ad hoc program Fitofarmaci e Fitoregolatori, Subproject. 7.Acknowledgments. We thank Prof. G. Jommi for helpful discussions related to this and previous articles on the same subject.  相似文献   

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Summary The increasing environmental and occupational exposure of populations to cadmium creates the need for biological indicators of cadmium exposure and toxicity. The advantages and disadvantages of monitoring blood cadmium, urinary, fecal, hair, and tissue cadmium, serum creatinine, 2-microglobulin, 1-antitrypsin and other proteins, and urinary amino acids, enzymes, total proteins, glucose 2-microglobulin, retinol-binding protein, lysozyme, and metallothionein are discussed. It is concluded that urinary cadmium, metallothionein and 2-microglobulin may be used together to assess cadmium, exposure and toxicity.  相似文献   

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Summary The essentiality of (-6) and (-3) fatty acids in mammals is well known. Nevertheless, some important points remain unclear concerning their implication in physiology. After a short discussion about the definition of essential fatty acids deficiency, this brief overview deals with some of these points, pointing out some of the unresolved questions. Different subjects are approached concerning the (-6) and (-3) fatty acids metabolism: desaturases, eicosanoids, production, as well as some of their metabolic effects on cell membranes, intestinal function, glucose and lipid metabolism, haemorheology.  相似文献   

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Zusammenfassung Mit Hilfe von Immunoelektrophorese und Doppeldiffusiontechnik wurden in Humanmilch an Blutplasmaproteinen serologisch identifiziert: Praealbumin, Albumin, Acid Seromucoid, 1-Glykoprotein (3·5 S), Coeruloplasmin, Haptoglobin, 2- oder-Lipoprotein, Transferrin, Fibrinogen, 2A-Globulin, 2M-Globulin und-Globulin.  相似文献   

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