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Attenuating Effect (attenuating + effect)
Selected AbstractsAttenuating effects of natural organic matter on microcystin toxicity in zebra fish (Danio rerio) embryos,benefits and costs of microcystin detoxicationENVIRONMENTAL TOXICOLOGY, Issue 1 2006Jimena Cazenave Abstract To contribute to the understanding of joined factors in the environment, impact of pure microcystins (-RR and -LF) on zebra fish (Danio rerio) embryos were investigated individually and in combination with a natural organic matter (NOM). The applied NOM was a reverse osmosis isolate from Lake Schwarzer See (i.e., Black Lake, BL-NOM). Teratogenic effects were evaluated through changes in embryonic development within 48 h of exposure. Detoxication activities were assessed by the activities of phase II biotransformation enzymes, soluble and microsomal glutathione S -transferase (s, mGST). Oxidative stress was assessed by determining both the production of hydrogen peroxide and by analyzing the activities of the antioxidative enzymes, guajacol peroxidase (POD), catalase (CAT), glutathione peroxidase (GPx), and the glutathione restoring enzyme glutathione reductase (GR). Energetic costs were evaluated by determining contents of fat, carbohydrates, and proteins in both exposed and control embryos. BL-NOM attenuated toxic effects of MC-LF and MC-RR verified by less pronounced teratological effects within 24 h, in particular, as well as less rise in the activity of s-GST, when compared with embryos exposed to either pure toxins or in combination with organic matter. BL-NOM also diminished oxidative effects caused by MC-LF; however, it failed to attenuate oxidative stress caused by MC-RR. Content of lipids was significantly reduced in exposed embryos following a trend similar to that obtained with teratological and enzymatic assays confirming the attenuating effect of BL-NOM. Physiological responses to microcystins and NOM required energetic costs, which were compensated to the expense of the energy resources of the yolk, which in turn might affect the normal development of embryos. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 22,32, 2006. [source] HIV protease inhibitors attenuate adherence of Candida albicans to epithelial cells in vitroFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2001Jasmin Bekti Abstract Oropharyngeal candidiasis is one of the first and most commonly reported opportunistic infections of untreated AIDS patients. With the introduction of the new antiviral HAART therapy, including HIV protease inhibitors, this mucocutaneous infection is nowadays only rarely observed in treated patients. It was recently shown that HIV protease inhibitors have a direct attenuating effect on Candida albicans secreted aspartic proteinases (Saps), an investigation prompted by the fact that both Sap and HIV protease belong to the superfamily of aspartic proteinases and by the observation that mucocutaneous infections sometimes resolve even in the absence of an immunological improvement of the host. As these Saps are important fungal virulence factors and play a key role in adhesion to human epithelial cells we tried to assess the effect of the HIV protease inhibitors Ritonavir, Indinavir and Saquinavir on fungal adhesion to these cells. The effect on phagocytosis by polymorphonuclear leukocytes was also assessed. Ritonavir was found to be the most potent inhibitor of fungal adhesion. A dose-dependent inhibition of adhesion to epithelial cells was found already at 0.8 ,M and was significant at 4 ,M or higher, at 500 ,M the inhibition was about 55%. Indinavir and Saquinavir inhibited significantly at 4 ,M or 20 ,M, respectively; at 500 ,M the inhibition was 30% or 50%. In contrast, no protease inhibitor was able to modulate phagocytosis of Candida by polymorphonuclear leukocytes. In conclusion, inhibition of Saps by HIV protease inhibitors may directly help to ease the resolution of mucosal candidiasis. In future, derivatives of HIV protease inhibitors, being more specific for the fungal Saps, may form an alternative in the treatment of mucosal candidiasis insensitive to currently available antimycotics. [source] Experimental evidence for the attenuating effect of SOM protection on temperature sensitivity of SOM decompositionGLOBAL CHANGE BIOLOGY, Issue 10 2010JEROEN GILLABEL Abstract The ability to predict C cycle responses to temperature changes depends on the accurate representation of temperature sensitivity (Q10) of soil organic matter (SOM) decomposition in C models for different C pools and soil depths. Theoretically, Q10 of SOM decomposition is determined by SOM quality and availability (referred to here as SOM protection). Here, we focus on the role of SOM protection in attenuating the intrinsic, SOM quality dependent Q10. To assess the separate effects of SOM quality and protection, we incubated topsoil and subsoil samples characterized by differences in SOM protection under optimum moisture conditions at 25 °C and 35 °C. Although lower SOM quality in the subsoil should lead to a higher Q10 according to kinetic theory, we observed a much lower overall temperature response in subsoil compared with the topsoil. Q10 values determined for respired SOM fractions of decreasing lability within the topsoil increased from 1.9 for the most labile to 3.8 for the least labile respired SOM, whereas corresponding Q10 values for the subsoil did not show this trend (Q10 between 1.4 and 0.9). These results indicate the existence of a limiting factor that attenuates the intrinsic effect of SOM quality on Q10 in the subsoil. A parallel incubation experiment of 13C-labeled plant material added to top- and subsoil showed that decomposition of an unprotected C substrate of equal quality responds similarly to temperature changes in top- and subsoil. This further confirms that the attenuating effect on Q10 in the subsoil originates from SOM protection rather than from microbial properties or other nutrient limitations. In conclusion, we found experimental evidence that SOM protection can attenuate the intrinsic Q10 of SOM decomposition. [source] Flaxseed attenuates the tumor growth stimulating effect of soy protein in ovariectomized athymic mice with MCF-7 human breast cancer xenograftsINTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Niina M. Saarinen Abstract In several epidemiological studies, a phytoestrogen-rich diet containing lignans and isoflavones is associated with reduced breast cancer risk, but experimental findings are controversial. In postmenopausal mammary cancer xenograft model, flaxseed (FS), a rich source of plant lignans, reduced breast cancer growth, while soy protein (SP), a rich source of isoflavones, enhanced it. The intake of phytoestrogens is increasing particularly among postmenopausal women, emphasizing the importance of elucidating their interactive effects on breast cancer. Our study determined the effect of FS and SP diets, alone and in combination, on the established human breast cancer MCF-7 tumor growth in ovariectomized athymic nude mice. Tumor bearing mice were divided into 4 groups and fed for 25 weeks either the basal diet (BD), or BD supplemented with 10% FS, 20% SP or 10% FS and 20% SP. After estrogen deprivation, FS regressed the tumor size similar to that of control. SP initially regressed the tumors but starting at week 13, the tumors regressed significantly less than in control and 43% of the tumors were regrowing until the end of the experiment and were significantly larger in size than in control. The combination of SP with FS reduced the tumor growth similar to that of control, as suggested also by the reduced tumor cell proliferation index. In conclusion, dietary FS did not stimulate the growth of estrogen responsive MCF-7 cancers in ovariectomized mice, while long-term consumption of SP did. Furthermore, FS reduced the tumor growth stimulating effect of SP to the same level as control, suggesting tumor growth attenuating effect of FS. © 2006 Wiley-Liss, Inc. [source] Involvement of 5-HT3 receptors in the development and expression of methamphetamine-induced behavioral sensitization: 5-HT3A receptor channel and binding studyJOURNAL OF NEUROCHEMISTRY, Issue 3 2006Ji-Hoon Yoo Abstract Methamphetamine (MAP) is one of the most commonly abused drugs in Asia, and previous studies suggest that serotonin 3 receptors (5-HT3) are involved in MAP-induced locomotion and reward. However, little is known about the role of 5-HT3 receptors in MAP-induced behavioral sensitization. Here, we measured the effects of MDL 72222, a 5-HT3 antagonist, and SR 57227 A, a 5-HT3 agonist, on the development and expression of MAP-induced behavioral sensitization, and alternations of 5-HT3 receptor binding labeled with the 5-HT3 -selective antagonist, [3H]GR65630, in mice. In addition, we investigated the effects of MAP on 5-HT3A receptor channel activity in Xenopus laevis oocytes expressing 5-HT3A receptors. We found that MDL 72222 attenuated both the development and expression of behavioral sensitization to MAP (1.0 mg/kg, i.p.), and that this attenuating effect of MDL 72222 was reversed by pre-treatment with SR 57227 A. In oocytes expressing 5-HT3A receptor, MAP exhibited a dual modulation of 5-HT3A receptor channel activity, i.e. pre-treatment with a low dose of MAP (0.1 µm) enhanced 5-HT-induced inward peak current (I5-HT) but a high dose of MAP (100 µm) inhibited I5-HT. The acute administration of MDL 72222 with MAP decreased [3H]GR65630 binding versus MAP alone in the mouse striatum. Our results suggest that MDL 72222 attenuates MAP-induced behavioral sensitization via 5-HT3 receptors in the caudate putamen, and that 5-HT3 receptor antagonists like MDL 72222 have potential as novel anti-psychotic agents for the treatment of MAP dependence and psychosis. [source] Displayed emotions and witness credibility: a comparison of judgements by individuals and mock juriesAPPLIED COGNITIVE PSYCHOLOGY, Issue 9 2007Janne Dahl Mock juries of 5,7 jurors viewed one of three video-recorded versions of a rape victim's testimony, role-played by a professional actress. The statement was given in a free-recall manner with one of three kinds of emotions displayed, termed congruent, neutral and incongruent emotional expressions. The juries were requested to reach a decision on items in a short questionnaire, probing the perceived credibility of the witness and judgements of the probability of a guilty verdict. The jurors were then asked to complete the questionnaire a second time, individually and anonymously. A control group filled out the questionnaire individually without preceding jury deliberations. When participants judged credibility and guilt independently, without a preceding jury discussion, the displayed emotions strongly influenced the judgements. However, discussions in the context of the jury strongly attenuated the effect of displayed emotion, with judgements converging on the credibility of a neutral emotional expression as judged by independent participants, and the attenuating effect outlasted the jury-situation. The results are consistent with research within social psychology showing that social stereotypes and prejudices are often neutralised by group discussions. Copyright © 2006 John Wiley & Sons, Ltd. [source] The potential antioxidant effect of raloxifene treatment: a study on heart, liver and brain cortex of ovariectomized female ratsCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2007Sibel Konyalioglu Abstract The antioxidant activity of some compounds buffer the free radicals generated either endogenously or exogenously, thus decreasing the potential damage mediated by oxidation. Recent studies documented that raloxifene has antioxidant properties in vitro. However, there are limited animal studies available to show raloxifene's antioxidant properties. We aimed to investigate the effects of raloxifene on antioxidant enzymes such as SOD, CAT and GPX, TrxR and the levels of GSH and MDA in heart, liver and brain cortex of ovariectomized female rats. Female Sprague Dawley rats weighing 300,350,g (n,=,24) were divided into three groups: (I) Eight non-ovariectomized rats were used as naive controls without any treatment (non-ovariectomized group, n,=,8). Five weeks after ovariectomy, (II) Ovariectomized placebo group (n,=,8) was given physiological saline, and (III) Raloxifene group (n,=,8) was given raloxifene 1,mg/kg,sc. daily for 12 days. Ovariectomy induced significant increases on SOD, GPX, CAT activity and MDA levels in brain, heart and liver tissues compared to non-ovariectomized rats (,p,<,0.05). Raloxifene treatment led to decreased levels of SOD activity in heart, GPX activity in brain and CAT activity in liver tissue when compared to ovariectomized group (,p,<,0.05) but there was no change in activity of TrxR in all groups. The levels of MDA in brain, heart and liver tissues increased in ovariectomized group when compared to non-overiectomized rats (,p,<,0.05). Raloxifene had a significant attenuating effect on the levels of MDA in brain and heart tissues. Our results also indicate that the levels of GSH in brain, heart and liver tissue decreased when compared to non-ovariectomized rats. Raloxifene treatment was observed to significantly increase the levels of GSH in brain and heart tissues (,p,<,0.05). However, there were insignificant differences for the GSH levels in liver tissues of ovariectomized placebo or raloxifene groups. In conclusion, our results demonstrate that raloxifene may be more effective against oxidative stress in heart and brain than in liver tissue. Copyright © 2006 John Wiley & Sons, Ltd. [source] Suppressive activity of fexofenadine hydrochloride on metalloproteinase production from nasal fibroblasts in vitroCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2004K. Asano Summary Background Allergic rhinitis (AR) is an inflammatory disease characterized by nasal wall remodelling with intense infiltration of eosinophils and mast cells/basophils. Matrix metalloproteinases (MMPs), MMP-2 and MMP-9, are the major proteolytic enzymes that induce airway remodelling. These enzymes are also important in the migration of inflammatory cells through basement membrane components. Objective We evaluated whether fexofenadine hydrochloride (FEX), the carboxylic acid metabolite of terfenadine with selective H1 -receptor antagonist activity, could inhibit MMP production from nasal fibroblasts (NFs) in response to TNF-, stimulation in vitro. Methods NFs were established from nasal polyp-derived fibroblasts (PFs) taken from patients with AR. Nasal mucosal fibroblasts (MFs) were also induced from nasal mucosal tissues from septal deformity patients without allergy. PF and MF (2 × 105 cells/mL, each) were stimulated with TNF-, in the presence of various concentrations of FEX. After 24 h, culture supernatants were obtained and assayed for MMP-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 levels by ELISA. The influence of FEX on mRNA expression of MMPs and TIMPs in 4 h-cultured cells was also evaluated by real-time RT-PCR. Furthermore, nuclear factor-,B (NF-,B) activation in fibroblasts treated with FEX for 4 h was examined by ELISA. Results FEX at more than 350 ng/mL inhibited the production of MMP-2 and MMP-9 from both PF and MF in response to TNF-, stimulation, whereas TIMP-1 and TIMP-2 production was scarcely affected by FEX. FEX also inhibited MMP mRNA expression and NF-,B activation in PF and MF after TNF-, stimulation. Conclusion The present data suggest that the attenuating effect of FEX on MMP-2 and -9 production from NFs induced by inflammatory stimulation may underlie the therapeutic mode of action of the agent on allergic diseases, including AR. [source] | |||||||||||||