Iron intake,oxidative stress-related genes and breast cancer risk

Iron has been suggested to contribute to breast cancer development through oxidative stress generation. Our study investigated associations between iron intake and breast cancer risk, overall and by menopausal and estrogen receptor/progesterone receptor (ER/PR) status, and modification by oxidative stress-related genetic polymorphisms (MnSOD, GSTM1 and GSTT1). A population-based case–control study (3,030 cases and 3,402 controls) was conducted in Ontario, Canada. Iron intake (total, dietary, supplemental, heme, nonheme) was assessed using a validated food frequency questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from multivariable logistic regression models. Interactions between iron intake and genotypes were assessed among 1,696 cases and 1,761 controls providing DNA. Overall, no associations were observed between iron intake and breast cancer risk. Among premenopausal women, total, dietary and dietary nonheme iron were positively associated with ER–/PR– breast cancer risk (all p_trend < 0.05). Among postmenopausal women, supplemental iron was associated with reduced breast cancer risk (OR_{>18 vs. 0 mg/day} = 0.68, 95% CI: 0.51–0.91), and dietary heme iron was associated with an increased risk, particularly the ER–/PR– subtype (OR_{highest vs. lowest quintile} = 1.69, 95% CI: 1.16–2.47; p_trend = 0.02). Furthermore, GSTT1 and combined GSTM1/GSTT1 polymorphisms modified some of the associations. For example, higher dietary iron was most strongly associated with increased breast cancer risk among women with GSTT1 deletion or GSTM1/GSTT1 double deletions (p_interaction < 0.05). Findings suggest that iron intake may have different effects on breast cancer risk according to menopausal and hormone receptor status, as well as genotypes affecting antioxidant capacity.     

阿克替苷通过激活血红素加氧酶-1抑制H_(2)O_(2)诱导的视网膜神经节细胞氧化损伤北大核心

目的研究阿克替苷对视网膜神经节细胞(RGC-5)的保护作用及其机制。方法将RGC-5细胞分为对照组、H_(2)O_(2)组、阿克替苷+H_(2)O_(2)组(1μmol·L^(-1)、10μmol·L^(-1)、30μmol·L^(-1)阿克替苷分别预处理细胞2 h),MTT法检测各组细胞活力;后续实验阿克替苷+H_(2)O_(2)组选择阿克替苷30μmol·L^(-1)作为治疗浓度,荧光探针H2DCF-DA检测活性氧(ROS)产生和罗丹明123检测线粒体膜电位,Western blot检测各组细胞中Bcl-2、Bcl-2/Bax、半胱氨酸蛋白酶-3(Caspase-3)蛋白表达。机制研究中首先用不同浓度阿克替苷单独处理RGC-5细胞24 h,Western blot检测血红素加氧酶-1(HO-1)蛋白表达水平,进一步锌原卟啉(ZnPP)预处理RGC-5细胞1 h,而后30μmol·L^(-1)阿克替苷单独预处理后与200μmol·L^(-1)H_(2)O_(2)共孵育24 h,通过MTT法测定细胞活力。结果与对照组相比,H_(2)O_(2)组中细胞活力明显降低(P<0.01)。与H_(2)O_(2)组相比,阿克替苷+H_(2)O_(2)组中10μmol·L^(-1)、30μmol·L^(-1)阿克替苷预处理可显著提高细胞活力(P<0.05、P<0.01)。与对照组相比,H_(2)O_(2)组RGC-5细胞ROS生成明显增加,线料体膜电位显著降低,同时Bcl-2/Bax比值降低和Caspase-3蛋白相对表达量增加(均为P<0.05)。与H_(2)O_(2)组相比,阿克替苷+H_(2)O_(2)组RGC-5细胞ROS生成减少,线粒体膜电位增加,Bcl-2/Bax比值提高,Caspase-3蛋白相对表达量减少(均为P<0.05)。与阿克替苷未处理组相比,阿克替苷剂量依赖性诱导HO-1蛋白的表达,与阿克替苷+H_(2)O_(2)组相比,加入ZnPP后细胞活力降低(P<0.01),说明HO-1抑制剂ZnPP降低了阿克替苷对H_(2)O_(2)损伤的抑制作用。结论阿克替苷能够通过上调HO-1表达抑制H_(2)O_(2)诱导的RGC-5氧化应激损伤。     

Gastrointestinal safety of coxibs: systematic review and meta‐analysis of observational studies on selective inhibitors of cyclo‐oxygenase 2

Prior meta‐analyses have shown a higher gastrointestinal risk of nonselective NSAIDs versus placebo and a lower gastrointestinal risk of coxibs versus nonselective NSAIDs. However, the available data about gastrointestinal risk for coxibs versus placebo are scarce. The aim of this study was to review the current evidence on the use of coxibs and to evaluate the risk of gastrointestinal adverse outcomes (GAO) associated with coxibs versus nonexposed. Search was conducted on PubMed and Embase databases. We selected cohort observational, case‐control, nested case‐control and case‐crossover studies that reported the risk of GAO associated with coxibs versus nonexposed as relative risk (RR), odds ratio (OR), hazard ratio (HR) or incidence rate ratio (IRR). It was estimated the pooled RR and the 95% confidence interval (CI) for coxibs both individually and as a whole by the DerSimonian and Laird method. Twenty‐eight studies met inclusion criteria. Overall, coxibs were associated with a significant increment in the risk of GAO [RR 1.64 (95% CI 1.44–1.86)]. The analysis by individual drugs showed that etoricoxib [RR 4.85 (95% CI 2.64–8.93)] presented the highest gastrointestinal risk, followed by rofecoxib [RR 2.02 (95% CI 1.56–2.61)] and celecoxib [RR 1.53 (95% CI 1.19–1.97)]. Gastrointestinal risk was also high for the subgroups aged <65 years and low‐dose coxibs. The use of coxibs is associated with a statistically significant increased risk of GAO, which would be high even for low‐dose coxibs and <65‐year‐old subgroups. The risk would be higher for etoricoxib than for celecoxib and rofecoxib.     

Curcumin ameliorates hepatic chronic inflammation induced by bile duct obstruction in mice through the activation of heme oxygenase-1

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Comprehensive analysis of gene expression of isolated pancreatic islets during pretransplant culture

Background: The aim of this study was to investigate the effect of pretransplant culture on the survival of pancreatic islet grafts, and to determine the biological characteristics of isolated islets during pretransplant culture. Methods: The survival of islets from Wistar rats, transplanted to diabetic C57BL/B6 mice, was compared between fresh islets and cultured islets. A comprehensive gene expression analysis was employed to investigate biological processes during pretransplant culture, and in vitro validation studies were performed. Results: Survival of cultured xenografts was significantly prolonged as compared to that of fresh islets (fresh: 12.5 ± 1.9 days, 1-day cultured: 16.0 ± 1.3 days (p= 0.017), 3-day cultured: 17.0 ± 2.6 days (p= 0.014)). Comprehensive gene expression analysis identified significant upregulation of annotated functions associated with inflammation in cultured groups. Six proinflammatory genes, including heme oxygenase 1 (HO-1) and IL-6, were significantly upregulated during culture. Validation studies revealed significantly higher levels of IL-6 in the supernatant of cultured islets and HO-1 in the cultured islets when compared with fresh islets. Conclusion: Transplantation of cultured islets induced significant but minimal prolongation of graft survival in xenogeneic combinations. Comprehensive analysis of gene expression in cultured islets showed biological processes associated with proinflammation during culture.     

Carbon monoxide controls microglial erythrophagocytosis by regulating CD36 surface expression to reduce the severity of hemorrhagic injury

Microglial erythrophagocytosis is crucial in injury response to hemorrhagic stroke. We hypothesized that regulation of microglial erythrophagocytosis via HO-1/CO depends on a pathway involving reactive oxygen species (ROS) and CD36 surface-expression. The microglial BV-2 cell line and primary microglia (PMG) were incubated +/−blood and +/−CO-exposure. PMG isolated from tissue-specific HO-1-deficient (LyzM-Cre-Hmox1 ^fl/fl) and CD36 ^−/− mice or siRNA against AMPK (AMP-activated protein kinase) were used to test our hypothesis. In a murine subarachnoid hemorrhage (SAH) model, we compared neuronal injury in wild-type and CD36 ^−/− mice. Readouts included vasospasm, microglia activation, neuronal apoptosis, and spatial memory. We observed increased microglial HO-1-expression after blood-exposure. A burst in ROS-production was seen after CO-exposure, which led to increased amounts of phosphorylated AMPK with subsequently enhanced CD36 surface-expression. Naïve PMG from LyzM-Cre-Hmox1 ^fl/fl mice showed reduced ROS-production and CD36 surface-expression and failed to respond to CO with increased CD36 surface-expression. Lack of HO-1 and CD36 resulted in reduced erythrophagocytosis that could not be rescued with CO. Erythrophagocytosis was enhanced in BV-2 cells in the presence of exogenous CO, which was abolished in cells treated with siRNA to AMPK. CD36 ^−/− mice subjected to SAH showed enhanced neuronal cell death, which resulted in impaired spatial memory function. We demonstrate that microglial phagocytic function partly depends on a pathway involving HO-1 with changes in ROS-production, phosphorylated AMPK, and surface expression of CD36. CD36 was identified as a crucial component in blood clearance after hemorrhage that ultimately determines neuronal outcome. These results demand further investigations studying the potential neuroprotective properties of CO.     

Cardioprotective effect of hemin in isoprenaline-induced myocardial infarction: role of ATP-sensitive potassium channel and endothelial nitric oxide synthase

Ischemic heart disease is a common cardiac health problem. Despite the significant advances in prevention and treatment of this disorder, its incidences and complications are very serious. So, the search for more antioxidants and anti-inflammatory agents with cardioprotective effects is an urgent task. We aimed to evaluate the effects of a heme oxygenase 1 (HO1) inducer, hemin (HEM), on isoprenaline (ISO)-induced myocardial damage. Forty-five Wistar albino rats were used. Animals were treated with HEM (25 mg/kg/day) i.p. for 5 days and injected with ISO (150 mg/kg/day) i.p. on 4th and 5th day of the experiment. Detection of the role of ATP-sensitive potassium channel (K_ATP) was performed by administration of glibenclamide (GP) (5 mg/kg/day) orally 2 h before HEM. Moreover, the role of endothelial nitric oxide synthase (eNOS) was detected by coadministration of Nitro- ω-L-arginine (L-NNA) (25 mg/kg/day) for 5 days. The ISO group showed increase in heart weight, cardiac enzymes, tumor necrosis factor alpha (TNFα), and malondialdehyde (MDA) with decrease in reduced glutathione (GSH), HO1, and total antioxidant capacity (TAC). In addition, there were increases in Bcl-2 associated X protein (Bax) and cleaved caspase-3, but decreases in B-cell lymphoma-2 (Bcl-2) and eNOS. Moreover, the histopathological examination of the ISO group showed degeneration of the cardiac muscle fibers and marked infiltration of the inflammatory cells. The biochemical and histopathological changes induced by ISO were markedly ameliorated in the HEM plus ISO group. This protective effect was diminished with coadministration of GP or L-NNA; thus, K_ATP and eNOS might mediate HEM cardioprotection.