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991.
Phyllis E. Hoar W. Glenn L. Kerrick 《Pflügers Archiv : European journal of physiology》1988,412(3):225-230
Two effects of Mn2+ on skinned fibers from chicken gizzard smooth muscle were observed, dependent on the presence of absence of dithiothreitol (DTT) reducing agent. One involves protein oxidation (in the absence of DTT) with production of a latch-like state, and the other involves direct Mn2+ activation of contractile proteins. Cells activated by Mn2+ in the presence of ATP and the absence of Ca2+, Mg2+ and DTT did not relax when transferred to normal relaxing solutions. In contrast, when 5 mM DTT was included in the Mn2+ contracting solution to prevent protein oxidation by Mn2+, the cells still contracted when exposed to Mn2+, but relaxed rapidly when the Mn2+ was removed. In the presence of DTT both the Mn2+ activation and the relaxation following removal of Mn2+ were more rapid than normal Ca2+-activated contractions and relaxations. The skinned fibers activated by Mn2+ in the absence of DTT showed little active shortening unless DTT was added. This rigor-like state is probably due to oxidation of contractile proteins since the cells relaxed when exposed to a relaxing solution containing DTT (50mM) and then contracted again in response to Ca2+ and relaxed normally. The Mn2+ activation was not associated with myosin light chain phosphorylation, in contrast to Ca2+-activated contractions.A preliminary report of this work was given at the Biophysical Society Meeting, February 1987: Hoar PE, Kerrick WGL (1987) Mn2+ activates skinned smooth muscle cells directly without myosin light chain phosphorylation and by reversible oxidation. Biophys J 51:332a 相似文献
992.
Ca2+-and voltage activated K+ channel in apical cell membrane of gallbladder epithelium fromTriturus
Y. Maruyama H. Matsunaga T. Hoshi 《Pflügers Archiv : European journal of physiology》1986,406(6):563-567
The presence of Ca2+- and voltage-activated K+ channels was directly demonstrated in the apical cell membrane of gallbladder epithelium by patch-clamp single-channel current recording. In K+-depolarized epithelial cells, negative pipette potentials induced outward current steps when the patch-pipette was filled with Na+-rich solution and these current steps were not affected by the presence or absence of Cl–. When K+-rich solution was in the pipette and K+-depolarized cells were examined, the current-voltage relations were linear with a single-channel conductance of 140 pS and polarity was reversed at 0 mV. In excised inside-out membrane patches, raising the free Ca2+ concentration of the medium facing the inner side of the membrane from 10–7 to 10–6 M evoked a marked increase in open state probability of the channels without affecting the elementary current steps. This suggests that intracellular Ca2+ as a second messenger plays a crucial role in the regulatory mechanism of the membrane potential by modulating the high-conductance apical K+ channels. 相似文献
993.
Henri J. Vial Jean R. Philippot Donald F.H. Wallach 《Molecular and biochemical parasitology》1984,13(1):53-65
The cholesterol synthesis of rhesus monkey erythrocytes parasitized by Plasmodium knowlesi and human erythrocytes infected by P. falciparum, as measured by incorporation of [1-14C]acetate and 3H2O, was almost undetectable, concordant with very low levels of measurable 3-hydroxy-3-methyl glutaryl-CoA reductase activity. In addition, both types of infected cells exchanged cholesterol with the plasma at the same rate as uninfected cells. The data do not exclude the possibility of cholesterol transfer from uninfected to infected cells. 相似文献
994.
E. Bursaux C. Poyart B. Bohn 《Pflügers Archiv : European journal of physiology》1976,365(2-3):213-220
Summary The effects of hypoxic hypoxia on renal hemodynamics and metabolism have been studied in anaesthetized mechanically ventilated rabbits. Acute hypoxia (F1O2=0.10,PaO2=35 torr) induces at constant mean arterial pressure a 45% decrease in RBF, GFR,
and
whereas free water clearance increases. These alterations were still apparent 50 min after resuming normal arterial oxygenation. In order to assess the role of the stimulation of catecholamine release in these observations, two other sets of experiments were performed: 1) the animals were ventilated with the same hypoxic gas mixture but after adrenergic blockade (phentolamine: 0.2 mg·kg·min–1 i.v.), 2) hypoxia was induced by ventilating the animals with CO (FICO=0.002) at constantPaO2. Increase in renal vascular resistance and reduction of renal O2 uptake were still observed. This indicates that adrenergic stimulation cannot fully explain the renal vasoconstriction encountered in hypoxia. The role of a local vasoactive factor, especially that of the renin angiotensin system is discussed. The apparent O2 cost of Na reabsorption was not greatly modified by any type of hypoxia and the Na:O2 ratio remained close to the value observed in normoxic animals. This indicates that the kidney may adapt to hypoxia by reducing its O2 demand keeping unaltered its tubular function and basal O2 needs. 相似文献
995.
An electron-cytochemical investigation was made of oxidation of 3,3-diaminobenzidine (DAB) in the brain of rats and man at different times after death. The oxidation product of DAB was localized in the mitochondria, lipofuscin granules, and erythrocytes. Oxidation of DAB by rat and human brain mitochondria was shown to be only very slightly depressed even 2 days after death.Laboratory of Experimental Pathology and Pathomorphology of the Brain, Institute of Psychiatry, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. V. Snezhnevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 757–759, June, 1976. 相似文献
996.
In vitro comparisons of induction of perforin (PFP), granzyme B (GRB), production of cytokines, and cell-mediated cytotoxicity by interleukin-2 (IL-2), interleukin-15 (IL-15), or combinational IL-2/IL-15-induced lymphokine-activated killer cells were studied in this study. Whereas IL-2-induction was associated with a decrease in cultured cell population over a 7-day period, IL-15 alone or in combination with IL-2 resulted in significant increase including cytotoxic T lymphocytes and subsets of CD56+ lymphocytes, particularly cytokine-induced killer and cytolytic natural killer-T lymphocytes. The overall PFP, GRB, and tumor necrosis factor-alpha expression in different subtypes were also significantly higher with IL-15 alone or in combination with IL-2 induction with resultant superior cytotoxicity compared to IL-2 treatment. There was no significant advantage of addition of IL-2 over IL-15 induction. These results offer further information on the cytotoxic potency of these cytokines and their mechanisms of action implicating potential use of IL-15 as part of cytokine adoptive immunotherapy. 相似文献
997.
998.
Ogier A Franco MA Charpilienne A Cohen J Pothier P Kohli E 《European journal of immunology》2005,35(7):2122-2130
Virus-like particles containing the rotavirus (RV) internal proteins VP2 and VP6 (2/6-VLP) have been shown to induce serum and fecal antibodies as well as protection in mice after intranasal administration with a mutant of E. coli toxin, LT-R192G. To better understand the origin of fecal IgA induced by this protocol, we studied the RV-specific B cell response in systemic and mucosal lymphoid tissues using a flow cytometry assay that allows quantification and phenotypic characterization of RV-specific B lymphocytes. We also assessed the RV-specific antibody-secreting cells in the spleen and intestinal lamina propria (ILP). A remarkably high frequency of RV-specific B cells was found in the respiratory lymphoid tissues and spleen, of which only a minority expressed the alpha4beta7 integrin (intestinal homing receptor). In contrast, but in accordance with alpha4beta7 expression at the induction site, a very low response was observed in intestinal lymphoid tissues (mesenteric lymph nodes and ILP), which did not increase after a second immunization. Thus, intranasal immunization with a nonreplicating antigen does not induce an important number of RV-specific B cells with an intestinal homing profile. 相似文献
999.
Activation of protease-activated receptor 2 stimulates proliferation and interleukin (IL)-6 and IL-8 secretion of endometriotic stromal cells 总被引:3,自引:0,他引:3
Hirota Y Osuga Y Hirata T Harada M Morimoto C Yoshino O Koga K Yano T Tsutsumi O Taketani Y 《Human reproduction (Oxford, England)》2005,20(12):3547-3553
BACKGROUND: Inflammation has been proposed to play essential roles in the pathophysiology of endometriosis, in which neutrophils and mast cells have been suggested to be involved. We studied whether the protease-activated receptor 2 (PAR2), which is activated by enzymes from neutrophils and mast cells, in endometriotic stromal cells (ESC) has any implication in the development of the disease. METHODS: Cultured ESC were stimulated with various concentrations of a specific PAR2 agonist peptide. Proliferating activity of the cells was determined using immunostaining of proliferating cell nuclear antigen (a cell proliferation marker), 5-bromo-2'-deoxyuridine incorporation into DNA and cell count. The concentrations of interleukin (IL)-6 and IL-8 were measured using specific enzyme-linked immunosorbent assay kits. The phosphorylation of three mitogen-activated protein kinases (MAPK), i.e. p38 MAPK, p42/44 MAPK and stress-activated protein Kinase/c-jun N terminal Kinase, in ESC was examined with Western blot analysis. RESULTS: Activation of PAR2 stimulated the proliferation of ESC and the secretion of IL-6 and IL-8 from ESC in a dose-dependent manner. Activation of PAR2 stimulated the phosphorylation of all three MAPK, and inhibitors of each MAPK suppressed the PAR2 activation-induced proliferation of ESC. CONCLUSIONS: The activation of PAR2 in ESC may be involved in the pathophysiology of endometriosis by inducing the growth and inflammation of endometriotic lesions. 相似文献
1000.
Unrelated patients with achromatopsia, macular degeneration with onset under age 50 years, cone degeneration or dysfunction, cone-rod degeneration, or macular malfunction were screened for mutations in the three genes known to be associated with achromatopsia: the GNAT2 gene encoding the alpha subunit of cone transducin and the CNGA3 and CNGB3 genes encoding the alpha and beta subunits of the cone cGMP-gated cation channel. We found no examples of patients with GNAT2 mutations. Out of 36 achromats, 12 (33%) had mutations in CNGA3 (13 different mutations including five novel mutations) and 12 (33%) had mutations in CNGB3 (six different mutations including four novel mutations). All achromats with CNG mutations had residual, presumably cone function as determined by computer-averaged 30-Hz electroretinograms (ERGs). There was considerable variability in acuity and color vision, with most patients having acuities of 20/200-20/400 and complete absence of color perception, and others having acuities of 20/25-20/40 and some color vision. Two pseudodominant achromatopsia cases were uncovered, both with CNGA3 mutations, including one family in which some compound heterozygotes with achromatopsia mutations were clinically unaffected. We found two novel CNGB3 changes in three patients with juvenile macular degeneration, a phenotype not previously associated with mutations in the cone channel subunits. These patients had subnormal acuity (20/30-20/60), normal to subnormal color vision, and normal to subnormal full-field cone ERG amplitudes. Our results indicate that some patients with channel protein mutations retain residual foveal cone function. Based on our findings, CNGB3 should be considered as a candidate gene to be evaluated in patients with forms of cone dysfunction, including macular degeneration. 相似文献