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961.
962.
Growth of a human leukemic T-cell line (CEM C7) in 10(-6) M dexamethasone results in inhibition of growth and rapid loss of cell viability after a delay of approximately 18 to 24 hours. Analysis of dexamethasone-treated cells by flow-microfluorometry showed that they were arrested in the G1 phase of the cell cycle. Loss of cell viability began at the same time as G1 accumulation was first detectable, and 20% of all cells were found to be blocked in G1 at this time suggesting that loss of viability and G1 arrest were coincident events. Half-maximal and maximal effects on both viability and G1 arrest after 48 hours in steroid were nearly identical with respect to steroid concentration and corresponded to half-maximal and full occupancy of glucocorticoid specific receptor by hormone, consistent with a glucocorticoid receptor mediated mechanism for both phenomena. Most non-viable cells were arrested in G1, and accumulation of cells in G1 was irreversible; removal of steroid in the presence of colcemid did not result in a decreased fraction of G1 cells. Furthermore, dexamethasone treatment did not protect cells against the effects of 33258 Hoechst-amplified killing of bromodeoxyuridine substituted cells exposed to light. These results show that dexamethasone arrests these leukemic cells in G1 and strongly suggest that dexamethasone-treated cells are killed upon entry into G1. 相似文献
963.
Marie Lipoldová Helena Havelková Jana Badalová Jarmila Vojtíšková Lei Quan Magdaléna Krulová Yahya Sohrabi Alphons P. Stassen Peter Demant 《Cancer immunology, immunotherapy : CII》2010,59(2):203-213
Low infiltration of lymphocytes into cancers is associated with poor prognosis, but the reasons why some patients exhibit
a low and others a high infiltration of tumors are unknown. Previously we mapped four loci (Lynf1–Lynf4) controlling lymphocyte infiltration of mouse lung tumors. These loci do not encode any of the molecules that are involved
in traffic of lymphocytes. Here we report a genetic relationship between these loci and the control of production of IFNγ
in allogeneic mixed lymphocyte cultures (MLC). We found that IFNγ production by lymphocytes of O20/A mice is lower than by
lymphocytes of OcB-9/Dem mice (both H2
pz
) stimulated in MLC by irradiated splenocytes of C57BL/10SnPh (H2
b
) or BALB/cHeA (H2
d
) mice, or by ConA. IFNγ production in MLCs of individual (O20 × OcB-9)F2 mice stimulated by irradiated C57BL/10 splenocytes and genotyped for microsatellite markers revealed four IFNγ-controlling
loci (Cypr4-Cypr7), each of which is closely linked with one of the four Lynf loci and with a cluster of susceptibility genes for different tumors. This suggests that inherited differences in certain
lymphocyte responses may modify their propensity to infiltrate tumors and their capacity to affect tumor growth. 相似文献
964.
B S Kasavina Iu F Ma?chuk T V Ukhina 《Biulleten' eksperimental'no? biologii i meditsiny》1983,95(3):44-45
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed. 相似文献
965.
G. B. Gerber 《Radiation and environmental biophysics》1982,20(4):235-243
Summary Interaction from several agents, i.e., a greater or smaller effects than expected from the sum of the individual effects can be of essentially two types: a) The agents could act in paralell on the same target, and a term depending on the doses of the agents involved would have to be added to the individual dose effect relationships (parergic interaction). b) The agents could act at different points in the chain of events leading to the observed effect, and the action of the second agent, the promotor, would be, at least in part, contingent on the action of the first inducer agent so that the dose effect relationships are linked in a multiplicative manner (metergic interaction). The dose effect surfaces for interaction depend on the type of dose effect relationship of the individual agents. Formulas are given for the general cases and are exemplified in graphs. Typical isobolic diagrams are also illustrated. These formulas may be adapted to experimental data by means of non-linear regression or maximum-likelihood analysis. 相似文献
966.
S M Strukova B A Umarova M G Golubeva M Kulibali T M Kalishevskaia 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(12):649-652
Heparin-regulated alpha-thrombin ability to activate the response of the anticoagulation system has been studied by the perfusion of sinocarotid area of rabbits with DIP-alpha-thrombin-heparin complex. In a series of experiments the area was perfused with 1.8 micron DIP-alpha-thrombin and significant changes in anticoagulation parameters have been registered in systemic circulation. During perfusion of sinocarotid area by DIP-alpha-thrombin-heparin complex (2 microns) no activation of anticoagulation system was noted. DIP-alpha-thrombin-heparin perfusates contained no endogenic heparin, unlike DIP-alpha-thrombin perfusates. This confirms the absence of anticoagulation system response to DIP-alpha-thrombin. Control perfusion by heparin alone in equimolar concentrations revealed no changes in anticoagulation system. It is assumed that heparin, blocking cation subcentre of the recognition centre for high molecular compounds in the enzyme molecule, prevents the response of anticoagulation system, disturbing the enzyme ability to bind to specific receptors of the vascular walls. 相似文献
967.
968.
Activation of heat shock response was observed after an alkaline shift of extracellular pH: it peaked at 5 to 10 min, as was previously reported for the heat-induced response, and was dependent on a functional rpoH gene, which is the positive regulator of the heat shock response. An induction of over sixfold was observed for dnaK and groE. The response was induced by the alkalization of extracellular pH but not by the alkalization of intracellular pH. An acidic shift of extracellular pH failed to activate the heat shock response, showing that the response is specific to the alkaline shift. 相似文献
969.
970.
The lipid dependence of pyrophosphatase activity was studied by treatment of liver and hepatoma microsomes with phospholipase C from Cl. perfringens and B. cereus and a subsequent incorporation of various classes of phospholipids into the delipidated microsomes. Phospholipase C hydrolysis sharply lowers the pyrophosphatase activity of liver and hepatoma microsomes. The enzyme activity is restored after introduction of phospholipids into delipidated liver microsomes, the maximal effect being achieved on incorporation of phosphatidylcholine. All the phospholipids tested exerted the same reactivation effects on the delipidated microsomes of hepatoma. However, a more complete delipidation of hepatoma microsomes by phospholipase C hydrolysis and a subsequent organic solvent extraction revealed a specific dependence of the enzyme activity on phosphatidylserine. 相似文献