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Stronger Inhibitory Effect (stronger + inhibitory_effect)
Selected AbstractsCytotoxicity assessment of gliotoxin and penicillic acid in Tetrahymena pyriformisENVIRONMENTAL TOXICOLOGY, Issue 2 2006C. Gräbsch Abstract Various studies have documented the associations between mold exposure and effects on health. Mycotoxins, which occur in spores and mold fragments, can be involved in processes that have pathological effects, such as adynamia of the immune system, recurrent infections of the respiratory tract, or asthma. Using Tetrahymena pyriformis, a single-cell organism well established as a suitable model for human respiratory epithelium-cell functionalities, we investigated dose,response relationships of the mycotoxins gliotoxin and penicillic acid. Our study focused on the viability (cell count, MTT assay), energy levels (adenosine-5,-triphosphate content), energy-providing processes (MTT reduction per cell), and cell respiration (oxygen consumption). Both mycotoxins acted as cytotoxins in a dose-dependent manner. Gliotoxin had a stronger inhibitory effect (EC50 0.38 ,M) than did penicillic acid (EC50 343.19 ,M). The energy-providing processes were not inhibited or were only weakly inhibited under the influence of gliotoxin, whereas penicillic acid caused stimulation of the physiological parameters. Summarizing the results, it is clear that the two investigated mycotoxins must have different modes of action. They are not only different in the strength of their toxic effects but also in a variety of physiological aspects. In addition, T. pyriformis showed differences in its ability to overcome the negative effects of particular mycotoxin exposures. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 111,117, 2006. [source] Discrepancy in glucose and fructose utilisation during fermentation by Saccharomyces cerevisiae wine yeast strainsFEMS YEAST RESEARCH, Issue 7 2004N.J. Berthels Abstract While unfermented grape must contains approximately equal amounts of the two hexoses glucose and fructose, wine producers worldwide often have to contend with high residual fructose levels (>2 g l,1) that may account for undesirable sweetness in finished dry wine. Here, we investigate the fermentation kinetics of glucose and fructose and the influence of certain environmental parameters on hexose utilisation by wine yeast. Seventeen Saccharomyces cerevisiae strains, including commercial wine yeast strains, were evaluated in laboratory-scale wine fermentations using natural Colombard grape must that contained similar amounts of glucose and fructose (approximately 110 g l,1 each). All strains showed preference for glucose, but to varying degrees. The discrepancy between glucose and fructose utilisation increased during the course of fermentation in a strain-dependent manner. We ranked the S. cerevisiae strains according to their rate of increase in GF discrepancy and we showed that this rate of increase is not correlated with the fermentation capacity of the strains. We also investigated the effect of ethanol and nitrogen addition on hexose utilisation during wine fermentation in both natural and synthetic grape must. Addition of ethanol had a stronger inhibitory effect on fructose than on glucose utilisation. Supplementation of must with assimilable nitrogen stimulated fructose utilisation more than glucose utilisation. These results show that the discrepancy between glucose and fructose utilisation during fermentation is not a fixed parameter but is dependent on the inherent properties of the yeast strain and on the external conditions. [source] Inhibitory activity of brown algal phlorotannins against hyaluronidaseINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2002Toshiyuki Shibata The inhibitory effect of brown algal phlorotannins on hyaluronidase was evaluated by an in vitro assay. Crude phlorotannins from the brown algae Eisenia bicyclis and Ecklonia kurome had a stronger inhibitory effect than well-known inhibitors such as catechins and sodium cromoglycate. IC50 values of the following six phlorotannins: phloroglucinol, an unknown tetramer, eckol (a trimer), phlorofucofuroeckol A (a pentamer), dieckol and 8,8,-bieckol (hexamers), were 280, 650, >800, 140, 120 and 40 ,M, respectively. The IC50 of catechin, epigallocatechin gallate and sodium cromoglycate was 620, 190 and 270 ,M, respectively. 8,8,-Bieckol, the strongest HAase inhibitor in this study, acted as a competitive inhibitor with an inhibition constant (Ki) of 35 ,M. Acetylation of the phlorotannins markedly decreased their inhibitory potency. [source] Chemically modified tetracyclines stimulate matrix metalloproteinase-2 production by periodontal ligament cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2006M. M. Bildt Background and Objective:, The purpose of this study was to investigate the effects of chemically modified tetracyclines (CMTs) on the production of gelatinases [matrix metalloproteinase (MMP)-2 and -9] by human periodontal ligament (PDL) cells, and on the activity of recombinant gelatinases. Material and Methods:, Human PDL cells were cultured with CMT-1, -3, -5, -7 or -8 in concentrations of 0, 1, 5, 10, 20, 50, 100, 200 and 500 µm. Gelatin zymography was used to determine MMP-2 and -9 production of the cells. The amount of DNA present in the cultures was analyzed using a fluorescent assay. The cytotoxicity of the CMTs was also determined. Recombinant human MMP-2 and -9 were incubated with the CMTs (0,500 µm) and their activity was analyzed using an internally quenched fluorogenic substrate. Results:, MMP-2 production was stimulated up to sevenfold by CMT-1, -3, -7 and -8 at low concentrations (10,200 µm). No significant amounts of MMP-9 were produced. In contrast, MMP-2 and -9 activity was reduced by ,,10,40-fold at higher concentrations (200,500 µm). CMT-5 had no effect on the production or on the activity of MMP-2 and -9. Only CMT-3 and -8 had cytotoxic effects on the PDL cells at the highest concentrations. Conclusion:, Surprisingly, CMTs are able to stimulate MMP-2 production at relatively low concentrations. However, at higher concentrations they exert a much stronger inhibitory effect on gelatinase activity. A possible stimulatory effect of CMTs on MMP production should be considered in their clinical use. [source] Expression of RhoA mRNA and activated RhoA in urothelium and smooth muscle, and effects of a rho-kinase inhibitor on contraction of the porcine urinary bladder,,NEUROUROLOGY AND URODYNAMICS, Issue 6 2009Kimihiro Nakanishi Abstract Aims To investigate the concentration and activity of RhoA in detrusor and urothelium, as well as the effects of a Rho-kinase inhibitor, Y-27632 {(+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride}, on contraction of the pig urinary bladder. Methods The concentration of RhoA mRNA was studied by the real-time RT-PCR and activated RhoA enzyme was studied by activation assay and Western blotting. In functional studies, the response to Y-27632 was examined in bladder strips with or without urothelium. Results The concentration of RhoA mRNA (n,=,38) and activated RhoA enzyme (n,=,19) were greater in urothelium than in detrusor. Tension decrease after administration of Y-27632 (1 nM to 100 µM) was significantly greater in tissues with urothelium than in tissues without urothelium, after pre-contraction with KCl (decrease by 52.0,±,4.6% vs. 28.0,±,6.8%, respectively; P,=,0.0088) or with carbachol (decrease by 53.1,±,7.2% vs. 30.6,±,5.8%, respectively; P,=,0.0035). Maximum contraction on CRC to carbachol was reduced significantly after administration of 3, 10, and 30 µM Y-27632 (to 72.2,±,6.8%, 43.9,±,7.1%, and 25.0,±,5.5%, respectively, of the control value) in strips with intact urothelium (n,=,36), but was reduced only at 10 and 30 µM (to 66.7,±,8.3% and 85.6,±,2.6%, respectively) in tissues without urothelium (n,=,20). Inhibitory effect of Y-27632 (3,30 µM) on the response to electrical field stimulation at 20 and 50 Hz was also greater in tissues with intact urothelium than in tissues without urothelium. Conclusions The concentration of RhoA mRNA and activated RhoA enzyme were greater in urothelium than in detrusor. Y-27632 showed a stronger inhibitory effect in detrusor with intact urothelium than in dose without urothelium. Neurourol. Urodyn. 28:521,528, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||