Gastroprotective effect of heme-oxygenase 1/biliverdin/CO pathway in ethanol-induced gastric damage in mice

Our objective was to evaluate the role of heme-oxygenase 1 (HO-1)/biliverdin/CO pathway in gastric defense against ethanol-induced gastric damage in mice. Mice were pre-treated with saline, hemin (HO-1 inducer), biliverdin (HO-1 product), dimanganese decacarbonyl (DMDC, CO donor) or zinc protoporphyrin IX (ZnPP IX, HO-1 antagonist). Another group received soluble guanylate cyclase (sGC) inhibitor (ODQ) 30 min before hemin, biliverdin or DMDC. After 30 min, gastric damage was induced by ethanol. After one hour, rats were sacrificed. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malonylaldehyde (MDA), glutathione (GSH) or bilirubin. HO-1 expression was determined after saline or ethanol administration by polymerase chain reaction (PCR) or immunohistochemistry. Ethanol (25% or 50%) induced gastric damage, increased MDA levels and reduced GSH in the gastric tissue. Ethanol 50% increased HO-1 mRNA transcripts, HO-1 immunoreactivity, and bilirubin concentration in gastric mucosa. Pre-treatment with hemin reduced gastric damage and MDA formation and increased GSH concentration in the gastric mucosa. ZnPP IX amplified the ethanol-induced gastric lesion, increased MDA formation and decreased GSH concentration in gastric mucosa. Biliverdin and DMDC reduced gastric damage and MDA formation and increased GSH concentration in the gastric tissue. ODQ completely abolished the DMDC protective gastric effect However, effects of hemin or biliverdin did not change with ODQ treatment. Our results suggest that HO-1/biliverdin/CO pathway plays a protective role against ethanol-induced gastric damage through mechanisms that can be dependent (CO) or independent (biliverdin) of sGC activation. (C) 2010 Elsevier B.V. All rights reserved.

Lipopolysaccharide from Escherichia coli prevents indomethacin-induced gastric damage in rats: role of non-protein sulfhydryl groups and leukocyte adherence

To investigate the role of non-protein sulfhydryl groups (NP-SH) and leukocyte adhesion in the protective effect of lipopolysaccharide (LPS) from Escherichia coli against indomethacin-induced gastropathy. Male Wistar rats were divided into four groups: saline, LPS, saline + indomethacin and LPS + indomethacin, with six rats in each group. Rats were pretreated with LPS (300 mu g/kg, by intravenous) or saline. After 6 h, indomethacin was administered (20 mg/kg, by gavage). Three hours after treatments, rats were killed. Macroscopic gastric damage, gastric NP-SH concentration, myeloperoxidase (MPO) activity and mesenteric leukocyte adhesion (intravital microscopy) were assessed. Statistical analysis was performed using one-way analysis of variance followed by the Newman-Keuls test. Statistical significance was set at P < 0.05. LPS reduced the gastric damage, gastric MPO activity and increased gastric NP-SH concentration in indomethacin-induced gastropathy. LPS alone increased gastric NP-SH when compared to saline. Indomethacin increased leukocyte adhesion when compared to the saline, and LPS reduced indomethacin-induced leukocyte adhesion. In addition, LPS alone did not change leukocyte adhesion, when compared to the saline. LPS protective effect against indomethacin-induced gastropathy is mediated by an increase in the NP-SH and a decrease in leukocyte-endothelial adhesion.

Hydrogen Sulfide Prevents Ethanol-Induced Gastric Damage in Mice: Role of ATP-Sensitive Potassium Channels and Capsaicin-Sensitive Primary Afferent Neurons

The aim of this study was to evaluate the protective effect of hydrogen sulfide (H(2)S) on ethanol-induced gastric lesions in mice and the influence of ATP-sensitive potassium (K(ATP)) channels, capsaicin-sensitive sensory afferent neurons, and transient receptor potential vanilloid (TRPV) 1 receptors on such an effect. Saline and L-cysteine alone or with propargylglycine, sodium hydrogen sulfide (NaHS), or Lawesson`s reagent were administrated for testing purposes. For other experiments, mice were pretreated with glibenclamide, neurotoxic doses of capsaicin, or capsazepine. Afterward, mice received L-cysteine, NaHS, or Lawesson`s reagent. After 30 min, 50% ethanol was administrated by gavage. After 1 h, mice were sacrificed, and gastric damage was evaluated by macroscopic and microscopic analyses. L-Cysteine, NaHS, and Lawesson`s reagent treatment prevented ethanol-induced macroscopic and microscopic gastric damage in a dose-dependent manner. Administration of propargylglycine, an inhibitor of endogenous H(2)S synthesis, reversed gastric protection induced by L-cysteine. Glibenclamide reversed L-cysteine, NaHS, or Lawesson`s reagent gastroprotective effects against ethanol-induced macroscopic damage in a dose-dependent manner. Chemical ablation of sensory afferent neurons by capsaicin reversed gastroprotective effects of L-cysteine or H(2)S donors (NaHS or Lawesson`s reagent) in ethanol-induced macroscopic gastric damage. Likewise, in the presence of the TRPV1 antagonist capsazepine, the gastroprotective effects of L-cysteine, NaHS, or Lawesson`s reagent were also abolished. Our results suggest that H(2)S prevents ethanol-induced gastric damage. Although there are many mechanisms through which this effect can occur, our data support the hypothesis that the activation of K(ATP) channels and afferent neurons/TRPV1 receptors is of primary importance.

Sonographic evaluation of endothelial function in letrozole and tamoxifen users

Objectives: Studies have shown that women previously treated for breast cancer present fewer cardiovascular events, indicating a possible protective effect of tamoxifen treatment. The effects of these aromatase inhibitors on cardiovascular protection remain controversial. The aim of this study was to compare some cardiovascular risk markers among breast cancer survivors following treatment with tamoxifen group (TMXg), letrozole group (LTZg) or no endocrine treatment group (NETg). Methods: A total of 103 breast cancer survivors: 35 using TMXg, 34 using letrozole group (LTZg) and 34 using no endocrine treatment group (NETg) were evaluated. Ultrasonographic evaluation of brachial artery flow-mediated dilation (FMD), carotid intima-media thickness (IMT) and stiffness index (beta); blood total cholesterol, HDL and triglycerides were assessed. Results: All three groups presented similar values of HDL and IMT. TMXg showed the lowest total cholesterol (219.29 +/- 36.31 mg/dL vs. 250.59 +/- 38.37 mg/dL vs. 245.09 +/- 35.35 mg/dL; TMXg vs. LTZg vs. NETg, respectively; p < 0.01-ANOVA), the highest triglycerides (139.34 +/- 41.82 mg/dL vs. 111.35 +/- 28.22 mg/dL vs.122.09 +/- 33.42 mg/dL; p < 0.01), the highest FMD (6.32 +/- 2.33% vs. 4.10 +/- 2.06% vs. 4.66 +/- 2.52%; p < 0.01) and the lowest stiffness index (beta) (5.08 +/- 1.68 vs. 6.28 +/- 1.75 vs. 5.99 +/- 1.86; p=0.01). LTZg did not differ significantly from NETg on any evaluated parameter. Conclusions: We did not observe any effect of LTZg on the evaluated cardiovascular risk parameters compared to NETg. As such, the observed difference on lipid values, stiffness index (beta) and FMD between women receiving tamoxifen anti letrozole might be best attributed to the beneficial effect of tamoxifen than to a detrimental effect of letrozole. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Knowledge and practices of medical students to prevent tuberculosis transmission in Rio de Janeiro, Brazil

Objectives. To describe knowledge, practices, and associated factors of medical students to prevent transmission of tuberculosis (TB) in five medical schools. Methods. Cross-sectional survey of undergraduate medical students in preclinical and in early and late clinical years. Information was obtained on sociodemographic profile, previous lectures on TB, knowledge about TB transmission, exposure to patients with active pulmonary TB, and use of respiratory protective masks. Results. Among 1 094 respondents, 575 (52.6%) correctly answered that coughing, speaking, and sneezing can transmit TB. Early [adjusted odds ratio = 4.0 (3.0, 5.5)] and late [adjusted odds ratio = 4.2 (3.1, 5.8)] clinical years were associated with correct answers, but having had previous lectures on TB was not. Among those who had previous lectures on TB, the rate of correct answers increased from 42.1% to 61.6%. Among 332 medical students who reported exposure to TB patients, 194 (58.4%) had not used protective masks. More years of clinical experience was associated with the use of masks [adjusted odds ratio = 2.9 (1.4, 6.1)], while knowledge was inversely associated with the use of masks [adjusted odds ratio = 0.4 (0.2, 0.6)]. Conclusions. Many medical students are not aware of the main routes of TB infection, and lectures on TB are not sufficient to change knowledge and practices. Regardless of knowledge about TB transmission, students engage in risky behaviors: more than two-thirds do not use a protective mask when examining an active TB case. We suggest innovative, effective active learning experiences to change this scenario.

Exercise reduces inflammation and cell proliferation in rat colon carcinogenesis

Purposes: There is evidence that the risk of colon cancer is reduced by appropriate levels of physical exercise. Nevertheless, the mechanisms involved in this protective effect of exercise remain largely unknown. Inflammation is emerging as a unifying link between a range of environment exposures and neoplastic risk. The carcinogen dimethyl-hydrazine (DMH) induces an increase in epithelial cell proliferation and in the expression of the inflammation-related enzyme cyclooxigenase-2 (COX-2) in the colon of rats. Our aim was to verify whether these events could be attenuated by exercise. Methods: Four groups of eight Wistar rats were used in the experiment. The groups G1 and G3 were sedentary (controls), and the groups G2 and G4 were submitted to 8 wk of swimming training, 5 d wk(-1). The groups G3 and G4 were given subcutaneous injections of DMH immediately after the exercise protocols. Fifteen days after the neoplasic induction, the rats were sacrificed and the colon was processed for histological examination and immunohistochemistry staining of proliferating cell nuclear antigen (PCNA) and COX-2. Results: We found a significant increase in the PCNA-labeling index in both DMH-treated groups of rats. However, this increase was significantly attenuated in the training group G4 (P < 0.01). Similar results were observed in relation to the COX-2 expression. Conclusions: From our findings, we conclude that exercise training exerts remarkable antiproliferative and antiinflammatory effects in the rat colonic mucosa, suggesting that this may be an important mechanism to explain how exercise protects against colonic cancer.

Role of the CYP2D6, EPHX1, MPO, and NQO1 Genes in the Susceptibility to Acute Lymphoblastic Leukemia in Brazilian Children

Polymorphic variations of several genes associated with dietary effects and exposure to environmental carcinogens may influence susceptibility to leukemia development. The objective of the present study was to evaluate the effect of the polymorphisms of debrisoquine hydroxylase (CYP2D6), epoxide hydrolase (EPHX1), myeloperoxidase (MPO), and quinone-oxoreductase (NQO1), which have been implicated in xenobiotic metabolism, on the risk of childhood acute lymphoblastic leukemia (ALL). We evaluated the frequency of polymorphisms in the CYP2D6 (*3 and *4), EPHX1 (*2 and *3), MPO (*2), and NQO1 (*2) genes in 206 patients with childhood ALL and in 364 healthy individuals matched for age and gender from a Brazilian population separated by ethnicity (European ancestry and African ancestry), using the PCR-RFLP method. The CYP2D6 polymorphism variants were associated with an increased risk of ALL. The EPHX1, NQO1, and MPO variant genotypes were significantly associated with a reduced risk of childhood ALL. A significantly stronger protective effect is observed when the EPHX1, NQO1, and MPO variant genotypes are combined suggesting that, CYP2D6 polymorphisms may play a role in the susceptibility to pediatric ALL, whereas the EPHX1, NQO1, and MPO polymorphisms might have a protective function against leukemogenesis. Environ. Mal. Mulagen. 51:48-56, 2010. (C) 2009 Wiley-Liss, Inc.

Impact of thymidylate synthase promoter and DNA repair gene polymorphisms on susceptibility to childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the frequency of polymorphisms in the TYMS, XRCC1, and ERCC2 DNA repair genes in pediatric patients with acute lymphoblastic leukemia using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) approaches. The study was conducted in 206 patients and 364 controls from a Brazilian population. No significant differences were observed among the analyzed groups regarding XRCC1 codon 399 and codon 194 and ERCC2 codon 751 and codon 312 polymorphisms. The TYMS 3R variant allele was significantly associated with a reduced risk of childhood ALL, represented by the sum of heterozygous and polymorphic homozygous genotypes (odds ratio 0.60; 95% confidence interval 0.37-0.99). The results suggest that polymorphism in TYMS may play a protective role against the development of childhood ALL.

Vitamin E and tannic acid improve DNA damage in rats submitted chronic ethanol administration

Purpose - Chronic ethanol consumption induces lipid peroxidation by increasing free radicals or reducing antioxidants and may increase damage to hepatic DNA. Tannins are polyphenolic metabolites present in various plants and one of their effects is antioxidant activity that reduces lipoperoxidation, as is the case for vitamin E. This paper aims to assess the role of tannic acid and vitamin E in lipid peroxidation and in DNA damage in rats receiving ethanol. Design/methodology/approach - A total of 60 Wistar rats were divided into six groups: control + ethanol (0-24hs), tannic acid + ethanol (0-24 hs), and vitamin E + ethanol (0-24 hs). The animals were sacrificed immediately (0 hour) or 24 hours after a period of four weeks of ethanol administration and the following measurements were made: plasma vitamin E and liver glutathione, thiobarbituric acid resistant substances, and a-tocopherol. The comet test was also applied to hepatocytes. Findings - Ethanol administration led to an increase in DNA damage (148.67 +/- 15.45 versus 172.63 +/- 18.94) during a period of 24 hours which was not detected in the groups receiving tannic acid or vitamin E. Steatosis was lower in the groups receiving tannic acid. Originality/value - The paper highlights that antioxidant role of vitamin E and of tannic acid in biological systems submitted to oxidative stress should be reevaluated, especially regarding the protective role of tannic acid against hepatic steatosis.

Ethanolic extract of Casearia sylvestris and its clerodane diterpen (caseargrewiin F) protect against DNA damage at low concentrations and cause DNA damage at high concentrations in mice`s blood cells

Casearia sylvestris is used in Brazil as a popular medicine to treat ulcer, inflammation and tumour. Caseargrewiin F is a clerodane diterpene isolated from the ethanolic leaf extract of C.sylvestris. The aim of the study was to assess the capacity of the ethanolic extract of C.sylvestris leaves and caseargrewiin F to protect DNA and verify if both the compounds cause some DNA damage, using the micronucleus (MN) test and comet assay in mice. Balb-C mice were treated with the extract [3.13, 6.25, 12.5, 25, 50 and 75 mg/kg body weight (b.w.)] and caseargrewiin F (0.16, 0.32, 0.63, 1.3, 2.5 and 3.8 mg/kg b.w.) for 14 days. On day 15, DNA damage was induced by intra-peritoneal (i.p.) injection of cyclophosphamide (CP) (i.p.) at 50 mg/kg b.w. after the MN test and comet assay were performed. A protective effect of ethanolic extract was observed in MN test (6.25 and 12.5 mg/kg b.w.) and the comet assay (3.13 and 6.25, 12.5 and 25 mg/kg b.w.). Caseargrewiin F showed protective effect at 0.63, 1.3 and 2.5 mg/kg b.w. only in comet assay. We also tested the ability of compounds of C.sylvestris to induce MN and to increase the comet assay tail moment. The experimental design was similar to the DNA protection assay except that in test groups we omitted the CP challenge. We observed increased damage at 50 and 75 mg/kg b.w. of ethanolic extract of C.sylvestris and caseargrewiin F at 3.18 mg/kg b.w. in both the MN test and comet assay. We conclude that ethanolic extract of C. sylvestris and caseargrewiin F can protect cells against DNA damage induced by CP at low concentrations, but at high concentrations these compounds also induce DNA damage.

NO EVIDENCE OF PATHOLOGICAL AUTOIMMUNITY FOLLOWING MYCOBACTERIUM LEPRAE HEAT-SHOCK PROTEIN 65-DNA VACCINATION IN MICE

Heat-shock proteins (HSPs) are currently one of the most promising targets for the development of immunotherapy against tumours and autoimmune disorders. This protein family has the capacity to activate or modulate the function of different immune system cells. They induce the activation of monocytes, macrophages and dendritic cells, and contribute to cross-priming, an important mechanism of presentation of exogenous antigen in the context of MHC class I molecules, These various immunological properties of HSP have encouraged their use in several clinical trials. Nevertheless, an important issue regarding these proteins is whether the high homology among HSPs across different species may trigger the breakdown of immune tolerance and induce autoimmune diseases. We have developed a DNA vaccine codifying the Mycobacterium leprae Hsp65 (DNAhsp65), which showed to be highly immunogenic and protective against experimental tuberculosis. Here, we address the question of whether DNAhsp65 immunization could induce pathological autoimmunity in mice. Our results show that DNAhsp65 vaccination induced antibodies that can recognize the human Hsp60 but did not induce harmful effects in 16 different organs analysed by histopathology up to 210 days after vaccination. We also showed that anti-DNA antibodies were not elicited after DNA vaccination. The results are important for the development of both HSP and DNA-based immunomodulatory agents.

Vascular endothelial growth factor genotypes and haplotypes are associated with pre-eclampsia but not with gestational hypertension

Vascular endothelial growth factor (VEGF) is relevant for normal pregnancy, and abnormalities in VEGF functions are associated with hypertensive disorders of pregnancy. Because there are few studies on how VEGF genetic polymorphisms affect susceptibility to pre-eclampsia (PE), and no studies on how they affect susceptibility to gestational hypertension (GH), we compared VEGF genotype and haplotype distributions in normotensive and hypertensive pregnancies. Genotypes and haplotypes for VEGF polymorphisms (C-2578A, G-1154A and G-634C) were determined in 303 pregnant women (108 healthy pregnant, HP; 101 with GH and 94 with PE). When white and non-white pregnant women were considered together, no significant differences were found in the distributions of VEGF genotypes or haplotypes (P > 0.05) in the three groups. However, with only white subjects, significant differences were found in genotypes distributions for two (C-2578A and G-634C) VEGF polymorphisms (both P < 0.05) between the HP and the PE groups. Importantly, the haplotype including the variants C-2578, G-1154 and C-634, which is associated with higher VEGF gene expression, was less common in the PE group compared with the HP group (4% versus 16%; P = 0.0047). However, we found no significant differences in VEGF haplotypes distributions when the HP and GH groups were compared (P > 0.05). These findings suggest a protective effect for the `C-2578, G-1154 and C-634` haplotype against the development of PE, but no major effects of VEGF gene variants on susceptibility to GH.

Inhibition of COX 1 and 2 prior to Renal Ischemia/Reperfusion Injury Decreases the Development of Fibrosis

Ischemia and reperfusion injury (IRI) contributes to the development of chronic interstitial fibrosis/tubular atrophy in renal allograft patients, Cyclooxygenase (COX) 1 and 2 actively participate in acute ischemic injury by activating endothelial cells and inducing oxidative stress. Furthermore, blockade of COX I and 2 has been associated with organ improvement after ischemic damage. The aim of this study was to evaluate the role of COX I and 2 in the development of fibrosis by performing a COX I and 2 blockade immediately before IRI We subjected C57BI/6 male mice to 60 min of unilateral renal pedicle occlusion, Prior to surgery mice were either treated with indomethacin (IMT) at days -1 and 0 or were untreated. Blood and kidney samples were collected 6 wks after IRI. Kidney samples were analyzed by real-time reverse transcription-poly me rase chain reaction for expression of transforming growth factor beta (TGF-beta), monocyte chemoattractant protein 1 (MCP-1), osteopontin (OPN), tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1 beta, IL-10, heme oxygenose 1 (HO-1), vimentin, connective-tissue growth factor (CTGF), collagen 1, and bone morphogenic protein 7 (BMP-7), To assess tissue fibrosis we performed morphometric analyses and Sirius red staining. We also performed immunohistochemical analysis of anti-actin smooth muscle, Renal function did not significantly differ between groups. Animals pretreated with IMT showed significantly less interstitial fibrosis than nontreated animals. Gene transcript analyses showed decreased expression of TGF-beta, MCP-1,TNF-alpha, IL-1-beta, vimentin, collagen 1, CTGF and IL-10 mRNA (all P < 0.05), Moreover, HO-I mRNA was increased in animals pretreated with IMT (P < 0.05) Conversely, IMT treatment decreased osteopontin expression and enhanced BMP-7 expression, although these levels did rot reach statistical significance when compared with control expression levels, I he blockade of COX 1 and 2 resulted in less tissue fibrosis, which was associated with a decrease in proinflammatory cytokines and enhancement of the protective cellular response.

Effect of isoflavone extracts from Glycine max on human endothelial cell damage and on nitric oxide production

Objective: In this study, we determined the protective effect of isoflavones from Glycine max on human umbilical vein endothelial cell (ECV304) damage induced by hydrogen peroxide (H(2)O(2)) and on nitric oxide (NO) production. Methods: We studied the regulation of NO synthesis in cultured human endothelial cells by phytoestrogens contained in soy extracts in the presence or absence of ICI 182,780 or N(omega)-nitro-L-arginine methyl esther and determined the protective effect of these isoflavones on ECV304 damage induced by H(2)O(2). Results: We show that soy extracts activate NO synthesis in endothelial cells and protect against cell damage. Conclusions: In conclusion, soy isoflavones markedly protect ECV304 cells against H(2)O(2) damage and promote NO synthesizing. Therefore, these isoflavones call potentially act as an NO promoter and as an antioxidant.

LipL53, a temperature regulated protein from Leptospira interrogans that binds to extracellular matrix molecules

The regulation of gene expression by environmental signals, such as temperature and osmolarity, has been correlated with virulence. In this study, we characterize the protein LipL53 from Leptospira interrogans, previously shown to react with serum sample of individual diagnosed with leptospirosis and to be up-regulated by shift to physiological osmolarity. The recombinant protein was expressed in Escherichia coli system, in insoluble form, recovered by urea solubilization and further refolded by decreasing the denaturing agent concentration during the purification procedure. The secondary structure content of the recombinant LipL53, as assessed by circular dichroism, showed a mixture of beta-strands and alpha-helix. The presence of LipL53 transcript at 28 degrees C was only detected within the virulent strains. However, upon shifted of attenuated cultures of pathogenic strains from 28 degrees C to 37 degrees C and to 39 degrees C, this transcript could also be observed. LipL53 binds laminin, collagen IV, cellular and plasma fibronectin in dose-dependent and saturable manner. Animal challenge studies showed that LipL53, although immunogenic, elicited only partial protection in hamsters. LipL53 is probably surface exposed as seen through immunofluorescence confocal microscopy. Our results suggest that LipL53 is a novel temperature regulated adhesin of L. interrogans that may be relevant in the leptospiral pathogenesis. (C) 2009 Elsevier Masson SAS. All rights reserved.