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排序方式: 共有184条查询结果,搜索用时 15 毫秒
41.
Cardiomyogenic differentiation of human adipose‐derived mesenchymal stem cells transduced with Tbx20‐encoding lentiviral vectors 下载免费PDF全文
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G A Zito S Callipari A Gambardella G Cennamo R Bencivenga M Verza A M Agliata M Varricchio 《Bollettino della Società italiana di biologia sperimentale》1989,65(2):143-146
The immune system in the aging man is known to show age-related defects; the study of the subpopulations in human blood has yielded conflicting results. This mostly seems to be due to the heterogeneity of the subjects admitted to immunogerontological studies. We investigated a group of aged persons fulfilling the admission criteria described in the "SENIEUR" protocol and strictness criteria dietetics. We found a decrease in the number of T cells, while the number of B cells and, above all, the report of the T4/T8 remained constant. There individuals should be considered as optimally healthy and immunologically uncompromised. 相似文献
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Pl-nectin is a component of the extracellular matrix that surrounds embryos of the sea urchin Paracentrotus lividus. Pl-nectin mediates adhesion of dissociated embryonic cells to substrates and interfering with ectodermic cells contacting Pl-nectin results in defects in skeleton growth and morphogenesis. Recently, we reported that Pl-nectin is a new member of the discoidin family, in agreement with the notion that many discoidin-containing proteins are involved in cell adhesion processes as integrin ligands. To better understand the molecular basis for the interaction of Pl-nectin with ectoderm, we investigated the hypothesis that Pl-nectin is an integrin ligand in sea urchin embryos. We show that in P. lividus embryos, βC-containing integrins localize to the apical surface of ectodermic cells, which are in contact with Pl-nectin. Immunoprecipitation experiments indicate that the two proteins are part of a complex in vivo and affinity chromatography indicates that βC-containing integrin receptors bind purified Pl-nectin. These data support a model in which ectodermic integrins binding to Pl-nectin mediate cellular adhesion to the hyaline layer. Regulated adhesion of cells to the hyaline layer is a critical component of several morphogenetic processes and the identification of the receptors and ligands involved provides new opportunities to investigate the underlying molecular mechanisms of ECM adhesion and morphogenesis. 相似文献
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The bacterial translocon interacts with both SecA-bound preproteins and nascent chain-ribosome complexes during Sec and signal recognition particle-dependent protein translocation, respectively. In their inactive state, translocons are saturated with ribosomes and SecA protein, reflecting the inherent affinity of these components for one another. We found that SecA and ribosomes are bound simultaneously and noncompetitively to a common set of inactive translocons. Furthermore, we demonstrate that at a later stage in binding, SecA possesses a ribosome-translocon dissociation activity that is coupled to its ATP-dependent membrane insertion and retraction cycle that drives protein translocation. This novel activity is presumably important in the commitment of the translocon to the Sec-dependent pathway. These results also provide a rationale for the compatibility and regulation of multiple protein translocation pathways that each makes distinct demands on a common translocon core. 相似文献
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Lead-catalyzed cleavage of ribonuclease P RNA as a probe for integrity of tertiary structure. 总被引:10,自引:3,他引:7 下载免费PDF全文
Pb(2+)-catalyzed cleavage of RNA has been shown previously to be a useful probe for tertiary structure. In the present study, Pb2+ cleavage patterns were identified for ribonuclease P RNAs from three phylogenetically disparate organisms, Escherichia coli, Chromatium vinosum, Bacillus subtilis, and for E. coli RNase P RNAs that had been altered by deletions. Each of the native RNAs undergoes cleavage at several sites in the core structure that is common to all bacterial RNase P RNAs. All the cleavages occur in non-paired regions of the secondary structure models of the RNAs, in regions likely to be involved in tertiary interactions. Two cleavage sites occur at homologous positions in all the native RNAs, regardless of sequence variation, suggesting common tertiary structural features. The Pb2+ cleavage sites in four deletion mutants of E. coli RNase P RNA differed from the native pattern, indicating alterations in the tertiary structures of the mutant RNAs. This conclusion is consistent with previously characterized properties of the mutant RNAs. The Pb2+ cleavage assay is thus a useful probe to reveal alteration of tertiary structure in RNase P RNA. 相似文献
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G Papaleo S Grano A B Gallo G A Zito 《Bollettino della Società italiana di biologia sperimentale》1978,54(21):2070-2074
IgA and IgM determination has been performed in the blood of the umbilical cord of 120 healthy newborn infants at different gestational ages. The utilization of the "Tripartigen Platelets" and "L.C. Partigen" has shown the extreme sensibility of the latter in determining minimum quantities of IgA and IgM. 相似文献
50.
Purification of Pseudomonas cytochrome oxidase (or nitrite reductase) by immunological methods 总被引:1,自引:0,他引:1
M C Silvestrini G Citro A Colosimo A Chersi R Zito M Brunori 《Analytical biochemistry》1983,129(2):318-325
A new purification procedure for the cytochrome oxidase from Pseudomonas aeruginosa based on immunoaffinity chromatography has been compared with the biochemical method and shown to be (i) fully competitive in terms of chemical homogeneity and enzymatic properties of the purified protein (ii) slightly less efficient in terms of total recovery and (iii) much more convenient in terms of the time required. A further evolution of the method that minimizes the number of purification steps and any stress to the native structure of the protein is suggested. 相似文献