Cytotoxicity and Membrane Interaction of Tamoxifen as Affected by Ca2+ and Mg2+: Use of a Bacterial Model System

A strain of Bacillus stearothermophilus was used as a model to study the interaction of tamoxifen (TAM) with the membrane and the cytostatic antiproliferative effects not related to estrogen binding. TAM inhibits the growth of B. stearothermophilus as a function of concentration. The supplementation of the growth medium with Ca2+ or Mg2+ partially relieves the growth inhibition by TAM, allowing growth at TAM concentrations that fully impair growth in the basal medium. Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and of its propionic acid derivative (DPH-PA) reveals opposite effects induced by TAM and Ca2+. The addition of Ca2+ to liposomes of bacterial lipids promoted physical ordering as opposed to disordering induced by TAM. Thus, it is predictable that growth impairment induced by TAM is mediated through perturbations at the membrane level.http://www.sciencedirect.com/science/article/B6TCP-3X3K8KK-Y/1/c91ad40c71c69da7245d8f09c634d28

Correlation of Helicobacter pylori genotypes with gastric histopathology in the central region of a South-European country

BACKGROUND: Outcome of Helicobacter pylori (H. pylori) infection results from interaction of multiple variables including host, environmental and bacterial-associated virulence factors. AIM: This study aimed to investigate the correlation of cagA, cagE, vacA, iceA and babA2 genotypes with gastric histopathology and disease phenotype in the central region of a South-European country. METHODS: This prospective study involved 148 infected patients (110 female; mean age 43.5 ± 13.4 years) submitted to endoscopy with corpus and antrum biopsies. H. pylori was cultured and DNA extracted from the isolates. Genotypes were determined by PCR. Histopathological features were graded according to the updated Sydney system and OLGA/OLGIM classification. Only patients with single H. pylori genotypes and complete histopathological results were included. RESULTS: Antrum samples presented higher degrees of atrophy, intestinal metaplasia, chronic inflammation and neutrophil activity. Genotype distribution was as follows: cagA-31.8 %; cagE-45.9 %; vacA s1a-24.3 %; vacA s1b-19.6 %; vacA s1c-0.7 %; vacA s2-55.4 %; vacA m1-20.9 %; vacA m2-79.1 %; vacA s1m1-18.9 %; vacA s1m2-25.7 %; vacA s2m1-2 %; vacA s2m2-53.4 %; iceA1-33.8 %; iceA2-66.2 %; babA2-12.2 %. CagA genotype was significantly associated with higher degrees of intestinal metaplasia, neutrophil activity, chronic inflammation and OLGIM stages. BabA2 was linked with higher H. pylori density. Strains with vacA s1m1 or vacA s1m1 + cagA positive genotypes had a significant association with peptic ulcer and vacA s2m2 with iron-deficient anemia. CONCLUSIONS: cagA, vacA s1m1 and babA2 genotypes are relatively rare in the central region of Portugal. cagA-positive strains are correlated with more severe histopathological modifications. This gene is commonly associated with vacA s1m1, and such isolates are frequently found in patients with peptic ulcer.info:eu-repo/semantics/publishedVersio

Tamoxifen induces ultrastructural alterations in membranes of Bacillus Stearothermophilus

Tamoxifen (TAM), a non-steroid antiestrogen, is the mostly used drug for chemotherapy and chemoprevention of breast cancer. However, the mechanisms by which TAM inhibits cell proliferation in breast cancer are not fully understood. TAM strongly incorporates in biomembranes and a variety of effects have been assigned to biophysical and biochemical interactions with membranes. Therefore, a better understanding of the physicochemical basis of interaction of TAM with biomembranes is essential to elucidate the molecular mechanisms of action. A strain of Bacillus stearothermophilus has been used as a model to clarify the interaction of TAM with the cell membrane. TAM effects on the ultrastructure of membranes of this bacterium were evaluated by electron microscopy. Important ultrastructural alterations were observed in B. stearothermophilus treated with TAM, namely change in the geometry of the membrane profile from asymmetric to symmetric, disaggregation of ribosomes, coagulation of the cytoplasmic matrix, occurrence of mesossomes, appearance of fractures in membranes and the alteration of the ultrastructure of cell wall. These ultrastructural alterations confirm that TAM is a membrane-active drug and that membrane damage may be involved in molecular mechanisms of cell death induced by this drug.http://www.sciencedirect.com/science/article/B6TCP-49C5CK6-4/1/3be4dd3d281e88dacdf66a7cc47250e

First detection and molecular characterization of hepatitis E virus in water from wastewater treatment plants in Portugal

Hepatitis E virus (HEV) genotype 3 is widespread in industrialized countries and widely recognized as a serious public health issue. HEV genotype 3 is excreted in both human and animal stools, having the potential to be introduced in aquatic environments through wastewater discharge. For this reason, waterborne transmission of the HEV genotype 3 is drawing increasing attention from the scientific community. Although studies in Portugal have shown that HEV circulates in both humans and swine, no study has yet focused on the presence of HEV in wastewater. Hence, a total of 60 water samples (influent and effluent) from 15 Wastewater Treatment Plants (WWTP) of different regions of Portugal were tested for the presence of HEV using a broad spectrum real-time RT-PCR with amplification within the ORF2 region of HEV genome. Positive samples were retested by nested RT-PCR with amplification within the ORF1 region, sequenced followed by phylogenetic analysis. HEV sequences were retrieved from two influent samples collected in December 2013 from WWTPs of North and Central of Portugal and classified in subgenotype 3i and 3f. This is the first study showing the presence of HEV in aquatic environments of Portugal

Helicobacter pylori antimicrobial resistance rates in the central region of Portugal

Helicobacter pylori resistance to antimicrobial agents is steadily increasing. It is extremely important to be aware of the local prevalence of antibiotic resistance so as to adjust treatment strategies. During this single-centre, prospective study, we aimed to determine primary and secondary resistance rates of H. pylori to antibiotics as well as host and bacterial factors associated with this problem. Overall, 180 patients (131 female; mean age 43.4±13.5 years; primary resistance 103; secondary resistance 77) with positive (13) C-urea breath test were submitted to upper endoscopy with gastric biopsies. Helicobacter pylori was cultured and antimicrobial susceptibility was determined by Etest and molecular methods. Clinical and microbiological characteristics associated with resistance were evaluated by logistic regression analysis. Among the 180 isolates 50% were resistant to clarithromycin (primary 21.4%; secondary 88.3%), 34.4% to metronidazole (primary 29.1%; secondary 41.6%), 33.9% to levofloxacin (primary 26.2%; secondary 44.2%), 0.6% to tetracycline and 0.6% to amoxicillin. Being female was an independent predictor of resistance to clarithromycin and metronidazole. Previous, failed, eradication treatments were also associated with a decrease in susceptibility to clarithromycin. History of frequent infections, first-degree relatives with gastric carcinoma and low education levels determined increased resistance to levofloxacin. Mutations in the 23S rRNA and gyrA genes were frequently found in isolates with resistance to clarithromycin and levofloxacin, respectively. This study revealed that resistance rates to clarithromycin, metronidazole and levofloxacin are very high and may compromise H. pylori eradication with first-line and second-line empiric triple treatments in Portugal

Non-Selective Toxicological Effects of the Insect Juvenile Hormone Analogue Methoprene. A Membrane Biophysical Approach

Abstract The Gram-positive bacterium, Bacillus stearothermophilus, was used as a model organism to identify the non-selective toxic effects of the currently used insecticide methoprene (isopropyl(2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate). A significant decrease of the yield of bacterial cultures and a premature appearance of ultrastructural abnormalities in cells cultured in the presence of the insecticide were taken as indicators of cytotoxicity. A putative correlation of this cytotoxicity with methoprene-induced perturbations on membrane lipid organization was investigated, using differential scanning calorimetry and the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its propionic acid derivative (DPH–PA). The membrane physical effects depended on the lipid bilayer composition and packing. The most striking effect was a progressive broadening and shifting to lower temperatures, with increasing methoprene concentrations, of the main transition phase of the dimyristoyl- or dipalmitoylphosphatidylcholine bilayers and of the lateral phase separation of liposomes reconstituted with the lipid extracts of B. stearothermophilus

Securitização da dívida rural brasileira: o caso do Banco do Brasil de 1995 a 2008

No começo da década de 90, produtores rurais estavam endividados e não conseguiriam pagar seus financiamentos se não tivesse havido a renegociação desses débitos, a denominada securitização de dívidas rurais. O Banco do Brasil tinha impactos negativos nos seus resultados ocasionados pela inadimplência dos produtores, principalmente por ser a instituição mais importante em termos de crédito rural. Após um longo processo de negociações, foi aprovada a Lei n. 9.138, de 1995, que deu início à denominada securitização das dívidas. A partir da interpretação das leis sobre a securitização e da análise dos dados contidos nos relatórios contábeis-financeiros do Banco do Brasil, fez-se uma análise detalhada sobre o comportamento econômico-financeiro dessa instituição e constatou-se que a securitização foi essencial para o banco reverter seus prejuízos em lucros