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841.
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844.
Endogenous CD8+ T cell expansion during regression of monoclonal EBV-associated posttransplant lymphoproliferative disorder. 总被引:5,自引:0,他引:5
V P Khatri R A Baiocchi R Peng A R Oberkircher J M Dolce P M Ward G P Herzig M A Caligiuri 《Journal of immunology (Baltimore, Md. : 1950)》1999,163(1):500-506
There are experimental data which suggest that the primary immune effector cell responsible for maintaining immune surveillance against the outgrowth of EBV-transformed B cells in humans is the CTL, but in vivo proof of this is lacking. In this study we perform a series of cellular and molecular assays to characterize an autologous, endogenous immune response against a transplantation-associated, monoclonal, EBV+ posttransplant lymphoproliferative disorder (PTLD). Following allogeneic bone marrow transplantation, a patient developed a monoclonal PTLD of donor B cell origin. With a decrease in immune suppression, we document the emergence of endogenous, donor-derived CD3+CD8+ CTLs, followed by regression of the PTLD. The TCR Vbeta repertoire went from a polyclonal pattern prior to the development of PTLD to a restricted TCR Vbeta pattern during the outgrowth and regression of PTLD. Donor-derived CD3+CD8+ T lymphocytes displayed MHC class I-restricted cytolytic activity against the autologous EBV+ B cells ex vivo without additional in vitro sensitization. The striking temporal relationship between the endogenous expansion of a TCR Vbeta-restricted, CD3+CD8+ population of MHC class I-restricted CTL, and the regression of an autologous monoclonal PTLD, provides direct evidence in humans that endogenous CD3+CD8+ CTLs can be responsible for effective immune surveillance against malignant transformation of EBV+ B cells. 相似文献
845.
846.
Cholesterol requirement for growth of mycoplasmas was tested in a serum-free medium supplemented with albumin, l-arginine, palmitic acid, and various concentrations of cholesterol dissolved in Tween 80. In cases in which Tween 80 was shown to inhibit growth, the test medium was supplemented with cholesterol dissolved in ethanol. Of the 31 species examined, all but Mycoplasma laidlawii, M. granularum, and Mycoplasma species strain S-743 exhibited a growth response to cholesterol. No requirement for cholesterol could be shown with the stable L-phase variants of Streptobacillus moniliformis and Proteus species. The results provide experimental support for the view that the large majority of the established Mycoplasma species require cholesterol for growth. 相似文献
847.
Effect of freezing and thawing on the conformation of phosvitin 总被引:1,自引:0,他引:1
G Taborsky 《The Journal of biological chemistry》1970,245(5):1054-1062
848.
The mutagenicity of 5-azacytidine and other inhibitors of replicative DNA synthesis in the L5178Y mouse lymphoma cell 总被引:3,自引:0,他引:3
The mutagenic potential of the cytidine analog, 5-azacytidine (Aza Cyd), was tested at the thymidine kinase (TK) gene locus of L5178Y mouse lymphoma cells. 3-h exposure to as little as 20 ng/ml Aza Cyd yielded a substantial increase in TK-deficient L5178Y cells as measured by drug-induced resistance to trifluorothymidine (TFTres) 48 h later. This mutagenic effect was diminished up to 75% when Aza Cyd was tested in the presence of either enzymatically active or heat-denatured 9000 X g supernatant prepared from rat liver homogenate. The mutagenicity of Aza Cyd was also decreased in the presence of 1-5 X 10(-3) M thymidine and eliminated in the presence of greater than 1 X 10(-5) M cytidine. Two L5178Y TK-deficient cell lines had no selective survival advantage compared to TK-competent L5178Y cell stock when plated in soft-agar medium that contained Aza Cyd. Four other specific inhibitors of scheduled DNA synthesis in mammalian cells, deoxyadenosine, aphidicolin, 1-beta-D-arabinofuranosylcytosine, and hydroxyurea were also L5178Y/TK mutagens. These data along with other published results suggest that chemicals known to disrupt nucleotide biosynthesis, alter deoxyribonucleotide pools, or directly inhibit DNA polymerase can cause stable, heritable increases in TFT resistance through mechanisms dependent upon altered replicative DNA synthesis, yet not necessarily dependent upon DNA incorporation or the binding of these mutagenic agents to nuclear DNA. 相似文献
849.
A G Gordon 《BMJ (Clinical research ed.)》1986,293(6553):1024-1025
850.
On the relationship between rate of ATP synthesis and H+ electrochemical gradient in rat-liver mitochondria 总被引:1,自引:0,他引:1
The relationship between rate of ATP synthesis, JATP, and value of the proton electrochemical gradient, delta mu H, has been analyzed in intact mitochondria. Onset of phosphorylation causes a depression of delta mu H of 1.5 kJ/mol. There is a close parallelism between inhibition of JATP and restoration of delta mu H to its state-4 value during titrations with oligomycin or atractyloside. Titrations with ionophores display the following features: (a) delta mu H can be depressed by 3-4 kJ/mol by valinomycin + K+ without affecting the rate of ATP synthesis; (b) uncouplers abolish JATP completely while depressing delta mu H by 3 kJ/mol; (c) complete abolition of ATP synthesis by inhibitors of electron transport is accompanied by a depression of delta mu H of only 1 kJ/mol. The results indicate that: (a) there is a close functional relationship between redox and ATPase H+ pumps, whereby inhibition of electron transfer is accompanied by simultaneous inhibition of the ATPase H+ pumps; and (b) uncoupling of oxidative phosphorylation is not due to depression of delta mu H per se. The consistence of the present data with either a chemiosmotic model where delta mu H is the sole and obligatory intermediate for energy coupling, or models where there is a direct transfer of energy between the two pumps is discussed. 相似文献