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981.
982.
28 anticancer agents have been surveyed for Epstein-Barr virus (EBV) activating potency. Two vinca alkaloids with antitubulin activity, vinblastine (VLB) and vincristine (VCR), enhanced the expression of EBV early antigens (EA) in a latently infected human lymphoblastoid cell line (Raji), when used in combination with n-butyrate. Other antitubulin agents, colchicine, colcemid, and podophyllotoxin, had the same effect, although their effects were less than that of the potent tumor promoter, 12-O-tetradecanoyl phorbol-13-acetate (TPA). 相似文献
983.
Mitogens trigger a calcium-independent signal for proliferation in phorbol-ester-treated lymphocytes
The activation of T lymphocytes by mitogens requires at least two signals; the first, delivered to T cells by a mitogen in conjunction with accessory cells (monocytes/macrophages), leads to the generation of the second signal, interleukin-2 (IL-2). The first signal also induces the expression of IL-2 receptors on the surface of a subpopulation of T cells; binding of IL-2 to its receptor then initiates a cascade of events culminating in DNA synthesis by these cells. Certain compounds act synergistically with mitogens in promoting T-cell proliferation by substituting for the activities of interacting cells or their products. For example, the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) has been shown to restore the ability of macrophage-depleted T-cell populations to respond to mitogenic lectins. Transmembrane fluxes of calcium, leading to increased free cytosolic calcium concentrations ([Ca2+]), have been demonstrated following mitogen binding to lymphocytes and have been implicated in the initiation of cell proliferation. We show here that the effect of TPA on lymphocyte proliferation occurs in the absence of extracellular Ca2+ or detectable changes in [Ca2+]i, but only in the presence of mitogens. This suggests that in cells which have been incubated with the phorbol ester, mitogens can induce proliferation by a calcium-independent signal. 相似文献
984.
Calmodulin is a regulator of several calcium-dependent cellular processes. It has been suggested that it plays a role in the mechanism of secretion. Employing an indirect immunoperoxidase technique at the light microscope level, this study demonstrates the presence of calmodulin in several exocytotic cells (mast cells, thyroid follicular cells, neurohypophyseal neurosecretory terminals, pancreatic beta-cells and pancreatic acinus cells) in rat and man. The positive staining reaction for calmodulin was granular and at least in the case of rat mast cells it appeared to be associated with the granule membrane. 相似文献
985.
986.
M. Alavaikko A. Rinne M. Järvinen V. K. Hopsu-Havu P. R. Meyer A. M. Levine R. J. Lukes 《Cellular and molecular life sciences : CMLS》1985,41(9):1173-1175
Summary One of two cases of acquired immune deficiency syndrome-related persistent generalized lymphadenopathy revealed a profoundly altered pattern of dendritic reticulum cells as demonstrated by immunoreactive acid cysteine proteinase inhibitor. The alterations could be related to totally or partially destructed lymphoid secondary follicles.Acknowledgments. This work has been partially supported by the grant from the Sigrid Juselius Foundation, Finland. 相似文献
987.
Summary Sleep deprivation was associated with decreased stature and it blunted the normal 24-h rhythm in young and in middle-aged men. Loss in stature was regained during the first recovery night of sleep. The 24-h rhythm in height is not an endogenous circadian rhythm but depends upon the periods of recumbency over the sleep/wake cycle.Acknowledgments. The first author was a Medical Research Council scholar; the second was supported by the Scottish Hospital Endowments Research Trust. 相似文献
988.
J. K. Saxena S. Khare A. K. Srivastava A. B. Sen S. Ghatak 《Cellular and molecular life sciences : CMLS》1985,41(4):472-474
Summary Changes in liver acid hydrolase activities during the infection of albino rats,Mastomys or mice withPlasmodium berghei are described. B-Glucosidase, B-galactosidase and N-acetyl-B-D-glucosaminidase exhibited widely different responses with acid phosphatase and cathepsin-B the least responsive and are likely to be causally related to immunity of animals. 相似文献
989.
990.
A key step for analysing the mechanochemistry of mitosis would be the isolation of a functional spindle capable of anaphase chromosome movement in vitro. Although Mazia and Dan first isolated spindles in 1952, with one or two possible exceptions, isolated spindles are non-functional. An alternative approach has used permeabilized cells to study anaphase chromosome movement, but these preparations are biochemically and morphologically complex, and hence difficult to analyse. We describe here a simple procedure for isolating diatom spindles which are capable of anaphase spindle elongation in vitro. With addition of ATP, the two half-spindles slide completely apart, with concomitant decrease in the zone of overlap. Electron microscopy reveals decreased numbers of microtubules throughout the spindle after ATP addition and confirms the complete absence of structures beyond the spindle poles. These results are inconsistent with theoretical models of mitosis which suggest that spindle poles are pushed apart by microtubule growth, are pulled apart by external forces applied to the poles, or are released from tension generated during spindle formation. The results are consitent with models that postulate mechanical interactions in the zone of microtubule overlap as a factor in spindle elongation. 相似文献