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A new synthetic route to tyrosine-O-sulfate-containing peptides based on the direct use of N alpha-acyltyrosine-O-sulfate is described and exemplified by the synthesis of the [Thr28,Leu31]cholecystokinin-pankreozymin-(25-33)-nonapeptide.  相似文献   

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Genetic counselling is a medical action which must be carried out by a M.D. specialized in genetics. Genetic counselling is peculiar in that couples rather than individuals are involved. Furthermore it is not concerned with the health of the consultants but with that of their expected children. Genetic counselling is not restricted to the statistical estimation of a risk; it raises important problems of psychology and behaviour. Finally, eugenic considerations about the diffusion of deleterious genes should not be taken into account in genetic counselling, which is given in the interest of individuals, not of the society. The increasing demand for genetic counselling is due to the change of the reproductive pattern. People do not want only to fix the size of their family, but also to avoid any accident of procreation.  相似文献   

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Experiments were carried out to investigate the relationship between the pattern of stimulus of efferent or afferent nerve and the size of action potential of frog's skin. Two kinds of preparations were used: the excised nerve skin preparation and the spinal preparation. In the range of moderate intervals of stimuli, the size of skin action potential of the nerve-skin preparation became larger with the increase of number of stimuli, (i) during a definite period of stimulation with various frequencies, or (ii) during various long periods of stimulation with constant frequency. The size of potential depended not only on number of stimuli but also on their interval. The latter property may be called pattern-sensitive. In some state of preparation the size of potential evoked by a constant number of stimuli was nearly constant, being independent from stimulus frequencies, that is, pattern insensitive. Both kinds of results were obtained in cases of the spinal preparation. Michaelis-Menten's equation could be applied to describe the relation between the size of potential and the number of stimuli. However, there was no reason to interprete this relation with a simple concentration-effect relationship. Another hypothesis was then testoned on the supposition that the response is composed of sequentially superposed unitary processes each of which was promptly evoked by each stimulus and decayed exponentially. The calculated response curve reasonably fit with the observed data. Slower processes commonly called accomodation were excluded from the present discussion and only the effect of relatively short period of stimulation was examined.  相似文献   

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