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H. Kalant 《CMAJ》1965,93(16):839-843
The chemical structures and reactions of penicillins and cephalosporins are reviewed in relation to their effects upon pharmacodynamic properties. The reactive betalactam ring is common to all penicillins and cephalosporin C analogues. This ring opens during acylation of the bacterial wall-building enzymes, but previous opening of the ring by acid or beta-lactamases destroys antibiotic activity.Semisynthetic substitutions may protect the ring by steric hindrance; this may actually inactivate certain penicillinases, so that resistant penicillins may potentiate penicillin G in some circumstances. However, the protective substitutions reduce the intrinsic activity of the synthetic penicillins themselves. Other properties which are affected include absorption, protein-binding, excretion, and possible allergenicity of the drugs. Effects on antibacterial spectrum may possibly be secondary to alteration of lipid solubility.  相似文献   

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H.E.M. 《CMAJ》1931,24(5):702-703
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Background  

We studied the pharmacology of l-methamphetamine, the less abused isomer, when used as a nasal decongestant.  相似文献   

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FMRFamide-related peptides (FaRPs) are the largest known family of invertebrate neuropeptides. Immunocytochemical screens of nematode tissues using antisera raised to these peptides have localized extensive FaRP-immunostaining to their nervous systems. Although 21 FaRPs have been isolated and sequenced from extracts of free-living and parasitic nematodes, available evidence indicates that other FaRPs await discovery. While our knowledge of the pharmacology of these native nematode neuropeptides is extremely limited, reports on their physiological activity in nematodes are ever increasing. All the nematode FaRPs examined so far have been found to have potent and varied actions on nematode neuromuscular activity. It is only through the extensive pharmacological and physiological assessment of the tissue, cell and receptor interactions of these peptidic messengers that an understanding of their activity on nematode neuromusculature will be possible. In this review, Aaron Maule and colleagues examine the current understanding of the pharmacology of nematode FaRPs.  相似文献   

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The Dying Animal     
The study of animal death is poised to blossom into an exciting new interdisciplinary field—and one with profound relevance for bioethics. Areas of interest include the biology and evolution of death-related behavior in nonhuman animals, as well as human social, psychological, cultural, and moral attitudes toward and practices related to animal death. In this paper, I offer a brief overview of what we know about death-related behavior in animals. I will then sketch some of the bioethical implications of this emerging field of research.  相似文献   

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Hilda Kean 《Anthrozo?s》2016,29(2):345-346
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