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We wanted to assess whether B-cell and/or T-cell responses to collagen and thereby the course of collagen-induced arthritis
could be suppressed by regulatory mechanisms associated with oral tolerance to an unrelated protein. DBA/1 mice were fed ovalbumin
(OVA)-containing pellets ad libitum for 1 week and subsequently coimmunized twice, with a mixture of bovine collagen type
II (BCII) and OVA in Freund's complete adjuvant. Mice fed OVA before coimmunization with BCII and OVA had significantly lower
arthritic scores than mice immunized with BCII only. Their body weight increased during the study period and their anti-BCII
antibody activity was significantly IgG2a lower. The frequency of spleen cells producing IgG anti-BCII antibody was also reduced. Coimmunization per se slightly ameliorated
the development of arthritis, resulting in an early, transient reduction. It resulted in significantly higher IgG1 anti-BCII antibody activity and increased splenocyte secretion of IFN-γ and IL-10 in response to BCII. Our findings demonstrate
that OVA-specific regulatory events induced by feeding OVA, i.e. bystander suppression, reduced the severity of arthritis
in animals immunized with BCII and OVA. Anti-BCII specific antibody responses and cytokine secretion by types 1 and 2 T helper
cells were also decreased. 相似文献
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B30.2-like domain proteins: update and new insights into a rapidly expanding family of proteins 总被引:5,自引:0,他引:5
Henry J; Mather IH; McDermott MF; Pontarotti P 《Molecular biology and evolution》1998,15(12):1696-1705
The B30.2 domain is a conserved region of around 170 amino acids associated
with several different protein domains, including the immunoglobulin folds
of butyrophilin and the RING finger domain of ret finger protein. We
recently reported several novel members of this family as well as
previously undescribed protein families possessing the B30.2 domain. Many
proteins have subsequently been found to possess this domain, including
pyrin/marenostrin and the midline 1 (MID1) protein. Mutations in the B30.2
domain of pyrin/marenostrin are implicated in familial Mediterranean fever,
and partial loss of the B30.2 domain of MID1 is responsible for Opitz G/BBB
syndrome, characterized by developmental midline defects. In this study, we
scrutinized the available sequence data bases for the identification of
novel B30.2 domain proteins using highly sensitive database-searching
tools. In addition, we discuss the chromosomal localization of genes in the
B30.2 family, since the encoded proteins are likely to be involved in other
forms of periodic fever, autoimmune, and genetic diseases.
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The potent enediyne antitumor antibiotic C1027 has been previously reported to induce novel DNA interstrand cross-links and drug monoadducts under anaerobic conditions [Xu et al. (1997) J. Am. Chem. Soc. 119, 1133-1134]. In the present study, we explored the mechanism of formation of these anaerobic DNA lesions. We found that, similar to the aerobic reaction, the diradical species of the activated drug initiates anaerobic DNA damage by abstracting hydrogen atoms from the C4', C1', and C5' positions of the A1, A2, and A3 nucleotides, respectively, in the most preferred 5'GTTA1T/5'ATA2A3C binding sequence. It is proposed that the newly generated deoxyribosyl radicals, which cannot undergo oxidation, likely add back onto the nearby unsaturated ring system of the postactivated enediyne core, inducing the formation of interstrand cross-links, connecting either A1 to A2 or A1 to A3, or drug monoadducts mainly on A2 or A3. Comparative studies with other enediynes, such as neocarzinostatin and calicheamicin gamma1I under similar reaction conditions indicate that the anaerobic reaction process is a kinetically competitive one, depending on the proximity of the drug unsaturated ring system or dioxygen to the sugar radicals and their quenching by other hydrogen sources such as solvent or thiols. It was found that C1027 mainly generates interstrand cross-links, whereas most of the anaerobic lesions produced by neocarzinostatin are drug monoadducts. Calicheamicin gamma1I was found to be less efficient in producing both lesions. The anaerobic DNA lesions induced by enediyne antitumor antibiotics may have important implications for their potent cytotoxicity in the central regions of large tumors, where relative anaerobic conditions prevail. 相似文献
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Nelson?DuránEmail author Priscyla?D?Marcato Oswaldo?L?Alves Gabriel?IH?De Souza Elisa?Esposito 《Journal of nanobiotechnology》2005,3(1):8
Extracellular production of metal nanoparticles by several strains of the fungus Fusarium oxysporum was carried out. It was found that aqueous silver ions when exposed to several Fusarium oxysporum strains are reduced in solution, thereby leading to the formation of silver hydrosol. The silver nanoparticles were in the
range of 20–50 nm in dimensions. The reduction of the metal ions occurs by a nitrate-dependent reductase and a shuttle quinone
extracellular process. The potentialities of this nanotechnological design based in fugal biosynthesis of nanoparticles for
several technical applications are important, including their high potential as antibacterial material. 相似文献
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Observations on a pro-esterase associated with partially purified first component of human complement (C''1) 总被引:18,自引:0,他引:18
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