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81.
Foamy retroviruses. A virus in search of a disease 总被引:13,自引:0,他引:13
82.
Summary Extensive copulatory experiences at a younger age provoked chronic changes in the reproductive physiology of old male rats. Continuous access to females was not necessary, sperm numbers were elevated in the 22-month-old males 7 months after a final sexual interaction. 相似文献
83.
T. Weiss 《Cellular and molecular life sciences : CMLS》1962,18(9):417-418
Zusammenfassung Bei Ratten wurde mittels «Spreading Depression» eine funktionelle Dekortikation erzeugt. Habituation und Deshabituation akustischer fortgeleiteter Potentiale (evoked responses) im Colliculus caudalis bleiben erhalten. Auch die reversible Abnahme der «evoked responses» während der Orientierungsreaktion bleibt erhalten. 相似文献
84.
Zusammenfassung In leichter Barbiturat- oder Chloralosenarkose wird die-Aktivität im Hippocampus, durch äussere oder retikulare Stimulierung induziert, von einer desynchronisierten Hippocampus-Aktivität abgelöst. Die Amplitude dieser durch Anästhetika hervorgerufenen langsamen hohen Wellen wird während der neocortikal sich ausbreitenden Depression reversibel verkleinert. 相似文献
85.
The synthesis of haemoglobin A (HbA) is exquisitely coordinated during erythrocyte development to prevent damaging effects from individual alpha- and beta-subunits. The alpha-haemoglobin-stabilizing protein (AHSP) binds alpha-haemoglobin (alphaHb), inhibits the ability of alphaHb to generate reactive oxygen species and prevents its precipitation on exposure to oxidant stress. The structure of AHSP bound to ferrous alphaHb is thought to represent a transitional complex through which alphaHb is converted to a non-reactive, hexacoordinate ferric form. Here we report the crystal structure of this ferric alphaHb-AHSP complex at 2.4 A resolution. Our findings reveal a striking bis-histidyl configuration in which both the proximal and the distal histidines coordinate the haem iron atom. To attain this unusual conformation, segments of alphaHb undergo drastic structural rearrangements, including the repositioning of several alpha-helices. Moreover, conversion to the ferric bis-histidine configuration strongly and specifically inhibits redox chemistry catalysis and haem loss from alphaHb. The observed structural changes, which impair the chemical reactivity of haem iron, explain how AHSP stabilizes alphaHb and prevents its damaging effects in cells. 相似文献
86.
Van Steen K McQueen MB Herbert A Raby B Lyon H Demeo DL Murphy A Su J Datta S Rosenow C Christman M Silverman EK Laird NM Weiss ST Lange C 《Nature genetics》2005,37(7):683-691
The Human Genome Project and its spin-offs are making it increasingly feasible to determine the genetic basis of complex traits using genome-wide association studies. The statistical challenge of analyzing such studies stems from the severe multiple-comparison problem resulting from the analysis of thousands of SNPs. Our methodology for genome-wide family-based association studies, using single SNPs or haplotypes, can identify associations that achieve genome-wide significance. In relation to developing guidelines for our screening tools, we determined lower bounds for the estimated power to detect the gene underlying the disease-susceptibility locus, which hold regardless of the linkage disequilibrium structure present in the data. We also assessed the power of our approach in the presence of multiple disease-susceptibility loci. Our screening tools accommodate genomic control and use the concept of haplotype-tagging SNPs. Our methods use the entire sample and do not require separate screening and validation samples to establish genome-wide significance, as population-based designs do. 相似文献
87.
The mammalian major histocompatibility complex (MHC; H-2 complex in mouse) is a large multigene complex which encodes cell-surface antigens involved in the cellular immune response to foreign antigens. Class I polypeptides expressed at the H-2K and H-2D loci of numerous mouse strains exhibit an unusually high degree of genetic polymorphism, which is assumed to be related to their function as primary recognition elements in the immune response. We suggested that this H-2 polymorphism may arise by gene conversion-like events between non-allelic class I genes. This is supported by our recent comparison of the DNA sequences of the normal H-2Kb gene sequence, from the C57BL/10 mouse, and a mutant form of this gene called H-2Kbm1: the mutant allele differs from the H-2Kb gene in seven bases out of a region of 13 bases in exon 3 of the class I gene (which encodes alpha 2 (C1) the second highly polymorphic protein domain), suggesting that this region of new sequence had been introduced into the H-2Kb sequence following unequal pairing of two class I genes in the genome of the C57BL mouse. Schulze et al. have obtained similar results. Here we report work identifying a potential donor gene in our library of 26 class I genes cloned from the C57BL/10 mouse. 相似文献
88.
89.
The T-cell antigen receptor (TCR) regulates two signal transduction pathways: the phosphatidylinositol (PtdIns) and tyrosine kinase pathways. Stimulation of T cells with antigen or anti-TCR monoclonal antibodies induces an increase in inositol phosphates and diacylglycerol, the second messengers responsible for the mobilization of cytoplasmic free calcium and activation of protein kinase C-4. The TCR also activates a tyrosine kinase that is not intrinsic to the TCR. The relationship between these two signal transduction pathways and their contribution to later T-cell responses is unclear. Studies using variants of a murine hybridoma suggested that the PtdIns pathway might not be necessary for or be involved in regulating interleukin-2 (IL-2) production. To address the relationship between later T-cell responses and the early biochemical signals, we investigated the ability of a heterologous receptor with defined signal transduction function to induce T-cell activation. The human muscarinic subtype-1 receptor (HM1), which elicits PtdIns metabolism in neuronal cells through a G protein-coupled mechanism, also functionally activates this pathway when expressed in the T-cell line Jurkat-derived host, J-HM1-2.2 (ref.8). We show here that stimulation of HM1 alone induced IL-2 production and IL-2 receptor alpha chain expression. HM1 does not induce the tyrosine kinase pathway, suggesting that this pathway does not directly influence later T cell-activation responses. Instead, our studies indicate that activation of the PtdIns pathway is probably sufficient to induce later T-cell responses. 相似文献
90.