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排序方式: 共有595条查询结果,搜索用时 78 毫秒
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Kundel HL; Gefter W; Aronchick J; Miller W Jr; Hatabu H; Whitfill CH; Miller W Sr 《Radiology》1997,205(3):859
5.
CTLA-4 is required for the induction of high dose oral tolerance 总被引:5,自引:3,他引:5
Samoilova EB; Horton JL; Zhang H; Khoury SJ; Weiner HL; Chen Y 《International immunology》1998,10(4):491-498
Mucosal and systemic administrations of high dose antigens induce long-
lasting peripheral T cell tolerance. We and others have shown that high
dose peripheral T cell tolerance is mediated by anergy or deletion and is
preceded by T cell activation. Co-stimulatory molecules B7-1 (CD80)/B7-2
(CD86) and their counter-receptors CD28/CTLA-4 play pivotal roles in T cell
activation and immune regulation. In the present study, we examined the
roles of the B7 co-stimulation pathway in the generation of high dose
peripheral T cell tolerance. We found that blocking B7:CD28/CTLA-4
interaction at the time of tolerance induction partially prevented T cell
tolerance, whereas selective blockade of B7:CTLA-4 interaction completely
abrogated peripheral T cell tolerance induced by either oral or i.p.
antigens. These results suggest that CTLA-4-mediated feedback regulation
plays a crucial role in the induction of high dose peripheral T cell
tolerance.
相似文献
6.
Molecular genetic characterization of XRCC4 function 总被引:2,自引:0,他引:2
XRCC4 is a generally expressed protein of 334 amino acids that is involved
in the repair of DNA double-strand breaks and in V(D)J recombination, but
its function is unknown. In this study, we have used a mutational approach
and the yeast two-hybrid method to perform an initial characterization of
this protein. We show that the XRCC4 protein is located in the nucleus. We
also demonstrate that several potential phosphorylation sites are not
required for XRCC4 function in a transient V(D)J recombination assay. In
addition, we show that XRCC4 forms a homodimer in vivo with the
homodimerization domain being located within amino acids 115-204. Finally,
we define a core domain of XRCC4 that functions in V(D)J recombination and
comprises amino acids 18-204. Potential functions of XRCC4 are discussed.
相似文献
7.
Mixed epithelial and stromal tumor of the kidney is a rare biphasic tumor composed of cysts and tubules embedded in the spindle cell stroma. Although the histogenesis of this tumor is unknown, it has been proposed that both components of the tumor, i.e., stromal and epithelial, are neoplastic. The authors report preliminary immunohistochemical and electron microscopic studies of the epithelial component from one case of a typical, benign, mixed epithelial, and stromal tumor of the kidney. In this study, some tubules showed positivity for proximal, while others showed positivity for distal, nephron immunomarkers. By electron microscopy, some tubules had features of proximal tubular epithelium, while other tubules had features of the loop of Henle (thin segments). The authors believe that in a benign tumor such morphologic heterogeneity is inconsistent with neoplastic proliferation. Therefore, they postulate that in mixed epithelial and stromal tumor of the kidney the tubules are entrapped rather than neoplastic. Additional studies are needed to address this issue and electron microscopy should play a significant role in this process. 相似文献
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P Wevers R Picken G Schmidt B Jann K Jann J R Golecki M Kist 《Infection and immunity》1980,29(2):685-691
A strain of Escherichia coli O18ac isolated from the stool sample of a patient with diarrhea was found to agglutinate human erythrocytes. From the results presented it is suggested that this hemagglutination is mediated by pili. Isolated pilus preparations agglutinated human erythrocytes, whereas pilus-negative mutants did not. The serological and chemical analyses indicate that the pili associated with E. coli O18ac are distinct from other types found with E. coli. 相似文献
10.
Nucleotide sequence of the gene for heat-stable enterotoxin II of Escherichia coli. 总被引:23,自引:11,他引:23
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Previously, the gene for heat-stable enterotoxin II (STII) has been mapped by transposon Tn5 insertion mutagenesis in the chimeric R-Ent plasmid pCG86 (Mazaitis, A. J., R. Maas, and W. K. Maas, J. Bacteriol. 145:97-105, 1981). DNA segments containing this gene were cloned from the wild-type and STII-insertion-mutant plasmid. The position of the Tn5 insertion was determined, and a 530-base-pair-long segment of the wild-type plasmid corresponding to the Tn5 insertion site was sequenced. An open reading frame for the STII gene was identified and is characterized by typical promoter and ribosome binding site sequences. The deduced STII structural gene codes for a protein 71 amino acids long, including a typical signal peptide of 23 amino acids and a mature protein of 48 amino acids. The size and overall structure of STII are similar to those of STI, but the amino acid compositions of the two heat-stable enterotoxins are completely different. 相似文献