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Zusammenfassung
l-undl-Isomere von Alanin und Serin sind beide wirksam, von der Antrumschleimhaut aus den Gastrinmechanismus zu aktivieren.
This work was supported by Veterans Administration research funds and by grants from the US Public Health Service. 相似文献
This work was supported by Veterans Administration research funds and by grants from the US Public Health Service. 相似文献
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HIV preferentially infects HIV-specific CD4+ T cells 总被引:34,自引:0,他引:34
Douek DC Brenchley JM Betts MR Ambrozak DR Hill BJ Okamoto Y Casazza JP Kuruppu J Kunstman K Wolinsky S Grossman Z Dybul M Oxenius A Price DA Connors M Koup RA 《Nature》2002,417(6884):95-98
HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption. 相似文献
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Zusammenfassung Nachweis, dass vollkoordinierte zweiwertige Kupfer- und Nickelchelate des 3,4,7,8-Tetramethyl-1,10-phenanthrolins Muskelkraft, wie auch Kontraktionsgeschwindigkeit des isolierten Meerschweinchen Atriums, sowie H3-Noradrenalin- und Metabolitenausfluss vermehren. Die durch Chelate veranlasste Senkung des Noradrenalins konnte durch Fluoreszenz-Histochemie bestätigt werden.
This work was commenced in the Department of Pharmacology, University of Melbourne and was presented in part by H. G. in November 1972 in partial fulfilment for the degree of B. Sc. (Hons) in the University of Melbourne. 相似文献
This work was commenced in the Department of Pharmacology, University of Melbourne and was presented in part by H. G. in November 1972 in partial fulfilment for the degree of B. Sc. (Hons) in the University of Melbourne. 相似文献
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R. A. Gregory Hilda J. Tracy M. I. Grossman D. de Valois R. Lichter 《Cellular and molecular life sciences : CMLS》1969,25(4):345-346
Zusammenfassung Die Isolierung von zwei Gastrinen aus der Magenschleimhaut von Hunden wird beschrieben. 相似文献
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Guo DC Pannu H Tran-Fadulu V Papke CL Yu RK Avidan N Bourgeois S Estrera AL Safi HJ Sparks E Amor D Ades L McConnell V Willoughby CE Abuelo D Willing M Lewis RA Kim DH Scherer S Tung PP Ahn C Buja LM Raman CS Shete SS Milewicz DM 《Nature genetics》2007,39(12):1488-1493
The major function of vascular smooth muscle cells (SMCs) is contraction to regulate blood pressure and flow. SMC contractile force requires cyclic interactions between SMC alpha-actin (encoded by ACTA2) and the beta-myosin heavy chain (encoded by MYH11). Here we show that missense mutations in ACTA2 are responsible for 14% of inherited ascending thoracic aortic aneurysms and dissections (TAAD). Structural analyses and immunofluorescence of actin filaments in SMCs derived from individuals heterozygous for ACTA2 mutations illustrate that these mutations interfere with actin filament assembly and are predicted to decrease SMC contraction. Aortic tissues from affected individuals showed aortic medial degeneration, focal areas of medial SMC hyperplasia and disarray, and stenotic arteries in the vasa vasorum due to medial SMC proliferation. These data, along with the previously reported MYH11 mutations causing familial TAAD, indicate the importance of SMC contraction in maintaining the structural integrity of the ascending aorta. 相似文献
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A pigment-binding protein essential for regulation of photosynthetic light harvesting 总被引:58,自引:0,他引:58
Photosynthetic light harvesting in plants is regulated in response to changes in incident light intensity. Absorption of light that exceeds a plant's capacity for fixation of CO2 results in thermal dissipation of excitation energy in the pigment antenna of photosystem II by a poorly understood mechanism. This regulatory process, termed nonphotochemical quenching, maintains the balance between dissipation and utilization of light energy to minimize generation of oxidizing molecules, thereby protecting the plant against photo-oxidative damage. To identify specific proteins that are involved in nonphotochemical quenching, we have isolated mutants of Arabidopsis thaliana that cannot dissipate excess absorbed light energy. Here we show that the gene encoding PsbS, an intrinsic chlorophyll-binding protein of photosystem II, is necessary for nonphotochemical quenching but not for efficient light harvesting and photosynthesis. These results indicate that PsbS may be the site for nonphotochemical quenching, a finding that has implications for the functional evolution of pigment-binding proteins. 相似文献
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