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81.
"The starting hypothesis of this paper was the actual occurrence of important interactions between demographic and socio-economic factors when trying to reach population forecasts that may be more efficient than those obtained by mere extrapolative methods. In order to be able to implement this approach to the Spanish case it has been necessary to reconstruct first the Spanish population series by age and sex groups from 1910 to 1980. Later, we proceed to obtain population forecasts using alternative modeling strategies and comment on the potential problems that the new demographic situation may have for future public policy." 相似文献
82.
Existence of a reactive zone in the interrenal gland of reptiles 总被引:1,自引:0,他引:1
E Del Conte 《Experientia》1972,28(4):451-453
83.
84.
85.
K G Peters J Marie E Wilson H E Ives J Escobedo M Del Rosario D Mirda L T Williams 《Nature》1992,358(6388):678-681
Stimulation of certain receptor tyrosine kinases results in the tyrosine phosphorylation and activation of phospholipase C gamma (PLC gamma), an enzyme that catalyses the hydrolysis of phosphatidylinositol (PtdIns). This hydrolysis generates diacylglycerol and free inositol phosphate, which in turn activate protein kinase C and increase intracellular Ca2+, respectively. PLC gamma physically associates with activated receptor tyrosine kinases, suggesting that it is a substrate for direct phosphorylation by these kinases. Here we report that a fibroblast growth factor (FGF) receptor with a single point mutation at residue 766 replacing tyrosine with phenylalanine fails to associate with PLC gamma in response to FGF. This mutant receptor also failed to mediate PtdIns hydrolysis and Ca2+ mobilization after FGF stimulation. However, the mutant receptor phosphorylated itself and several other cellular proteins, and it mediated mitogenesis in response to FGF. These findings show that a point mutation in the FGF receptor selectively eliminates activation of PLC gamma and that neither Ca2+ mobilization nor PtdIns hydrolysis are required for FGF-induced mitogenesis. 相似文献
86.
M. D. Gomar B. Fernández C. M. Del Aguila J. L. Castillo G. Escames D. Acuña-Castrovejo 《Cellular and molecular life sciences : CMLS》1995,51(3):209-212
In this study, we examined the effect of intracerebroventricular (i.c.v) injection of melatonin and/or ACTH1–10 and ACTH4–10 on [3H]flunitrazepam binding sites in the cerebral cortex of hypophysectomized rats. Hypophysectomy increased the Bmax (maximum number of binding sites) of benzodiazepine (BNZ) receptors for at least 7 days after surgery, without changing KD (dissociation constant). The i.c.v. injection of melatonin to hypophysectomized rats significantly increased Bmax, whereas the same doses of melatonin were ineffective in sham-operated animals. In both cases, KD values were unchanged. The i.c.v injection of ACTH1–10 to hypophysectomized animals significantly increased Bmax, an effect that was enhanced by simultaneous i.c.v. injection of ACTH1–10+melatonin, reaching higher values of Bmax than the i.c.v. injection of these hormones individually. No significant changes in KD values were found after ACTH1–10 and/or melatonin administration. However, the i.c.v. injection of ACTH4–10 to hypophysectomized rats did not change Bmax, although it significantly increased KD values, indicating a decrease in the BNZ binding affinity. Melatonin injection counteracted this effect of ACTH4–10, returning KD to the control value. Moreover, although the lower dose of i.c.v. melatonin used, 10 ng, was unable to modify Bmax of BNZ binding in the ACTH4–10-injected group, the higher dose, 20 ng, significantly increased Bmax. The results suggest that these ACTH-derived peptides can modulate the effect of melatonin on brain benzodiazepine receptors. 相似文献
87.
iASPP preferentially binds p53 proline-rich region and modulates apoptotic function of codon 72-polymorphic p53 总被引:6,自引:0,他引:6
Bergamaschi D Samuels Y Sullivan A Zvelebil M Breyssens H Bisso A Del Sal G Syed N Smith P Gasco M Crook T Lu X 《Nature genetics》2006,38(10):1133-1141
iASPP is one of the most evolutionarily conserved inhibitors of p53, whereas ASPP1 and ASPP2 are activators of p53. We show here that, in addition to the DNA-binding domain, the ASPP family members also bind to the proline-rich region of p53, which contains the most common p53 polymorphism at codon 72. Furthermore, the ASPP family members, particularly iASPP, bind to and regulate the activity of p53Pro72 more efficiently than that of p53Arg72. Hence, escape from negative regulation by iASPP is a newly identified mechanism by which p53Arg72 activates apoptosis more efficiently than p53Pro72. 相似文献
88.
Kras is the most frequently mutated ras family member in lung carcinomas, whereas Hras mutations are common in tumors from stratified epithelia such as the skin. Using a Hras knock-in mouse model, we demonstrate that specificity for Kras mutations in lung and Hras mutations in skin tumors is determined by local regulatory elements in the target ras genes. Although the Kras 4A isoform is dispensable for mouse development, it is the most important isoform for lung carcinogenesis in vivo and for the inhibitory effect of wild-type (WT) Kras on the mutant allele. Kras 4A expression is detected in a subpopulation of normal lung epithelial cells, but at very low levels in lung tumors, suggesting that it may not be required for tumor progression. The two Kras isoforms undergo different post-translational modifications; therefore, these findings can have implications for the design of therapeutic strategies for inhibiting oncogenic Kras activity in human cancers. 相似文献
89.
This paper publishes the correspondence between S. Germain and C.F. Gauss. The mathematical notes enclosed in her letters are published for the first time. These notes, in which she submitted some of her results, proofs and conjectures to Gauss for his evaluation, were inspired by her study of the Disquisitiones Arithmeticae. The interpretation of these mathematical notes not only shows how deeply she went into Gauss’s treatise and mastered it long before any other mathematician, but also, more importantly, shows that she obtained interesting results in the theory of power residues that have never previously been attributed to her. 相似文献
90.
M. Rguez-Mariscal A. S. Del Barrio J. Larralde J. A. Martínez 《Cellular and molecular life sciences : CMLS》1993,49(4):308-312
The administration of metaproterenol induced an increase in gastrocnemius muscle weight without change in body growth rate or tissue protein concentrations, while epididymal fat was reduced. This effect was accompanied by an enhancement in the levels of intracellular amino acids in muscle. By contrast, liver amino acids were unaffected by treatment with the mixed -adrenergic agonist. 相似文献