N.S.K. Ramli

The effect of environmental conditions on biofilm formation of Burkholderia pseudomallei clinical isolates.

Burkholderia pseudomallei, a Gram-negative saprophytic bacterium, is the causative agent of the potentially fatal melioidosis disease in humans. In this study, environmental parameters including temperature, nutrient content, pH and the presence of glucose were shown to play a role in in vitro biofilm formation by 28 B. pseudomallei clinical isolates, including four isolates with large colony variants (LCVs) and small colony variants (SCVs) morphotypes. Enhanced biofilm formation was observed when the isolates were tested in LB medium, at 30°C, at pH 7.2, and in the presence of as little as 2 mM glucose respectively. It was also shown that all SVCs displayed significantly greater capacity to form biofilms than the corresponding LCVs when cultured in LB at 37°C. In addition, octanoyl-homoserine lactone (C8-HSL), a quorum sensing molecule, was identified by mass spectrometry analysis in bacterial isolates referred to as LCV CTH, LCV VIT, SCV TOM, SCV CTH, 1 and 3, and the presence of other AHLs with higher masses; decanoyl-homoserine lactone (C10-HSL) and dodecanoyl-homoserine lactone (C12-HSL) were also found in all tested strain in this study. Last but not least, we had successfully acquired two Bacillus sp. soil isolates, termed KW and SA respectively, which possessed strong AHLs degradation activity. Biofilm formation of B. pseudomallei isolates was significantly decreased after treated with culture supernatants of KW and SA strains, demonstrating that AHLs may play a role in B. pseudomallei biofilm formation.

Draft Genome Sequences of Helicobacter pylori Isolates from Malaysia, Cultured from Patients with Functional Dyspepsia and Gastric Cancer

Helicobacter pylori is the main bacterial causative agent of gastroduodenal disorders and a risk factor for gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. The draft genomes of 10 closely related H. pylori isolates from the multiracial Malaysian population will provide an insight into the genetic diversity of isolates in Southeast Asia. These isolates were cultured from gastric biopsy samples from patients with functional dyspepsia and gastric cancer. The availability of this genomic information will provide an opportunity for examining the evolution and population structure of H. pylori isolates from Southeast Asia, where the East meets the West.

Testosterone enhances expression and functional activity of epithelial sodium channel (ENaC), cystic fibrosis transmembrane regulator (CFTR) and sodium hydrogen exchanger (NHE) in vas deferens of sex-steroid deficient male rats

HighlightsTestosterone affects vas deferens fluid secretion rate, pH, HCO3−, Cl− and Na+ concentration.Testosterone effects were antagonized by amiloride and Cftr inh‐172.Testosterone effects were antagonized by flutamide and finasteride.Testosterone increased expression of &ggr;‐ENaC, CFTR and NHE 1, 2, 3 and 4 in vas deferens.These proteins were differentially expressed in vas deferens epithelium under testosterone influence. ABSTRACT Effects of testosterone on expression and functional activity of ENaC, CFTR and NHE in vas deferens were investigated. Methods: Orchidectomized, adult male rats were given 125 and 250 &mgr;g/kg/day testosterone subcutaneously, with or without flutamide and finasteride for seven consecutive days. At the end of the treatment, rats were anesthetized and vas deferens were perfused. Changes in vas deferens fluid secretion rate, pH, HCO3−, Cl− and Na+ concentrations were recorded in the presence of amiloride and Cftr inh‐172. Rats were then sacrificed and vas deferens were harvested and subjected for molecular biological analysis. Results: Testosterone treatment caused the fluid pH and HCO3− concentrations to decrease but secretion rate, Cl− and Na+ concentrations to increase, where upon amiloride administration, the pH and HCO3− concentration increased but Cl− and Na+ concentrations further increased. In testosterone‐treated rats, administration of Cftr inh‐172 caused all fluid parameters to decrease. In testosterone‐treated rats co‐administered with flutamide or finasteride, pH and HCO3− concentration increased but fluid secretion rate, Cl− and Na+ concentrations decreased and these parameters were not affected by amiloride or Cftr inh‐172 administration. Under testosterone influence, CFTR and &ggr;‐ENaC were highly expressed at the apical membrane while NHE‐1 and 4 were highly expressed at the basolateral membrane of vas deferens epithelium. Meanwhile, NHE‐2 and 3 were highly expressed at the apical membrane. Conclusions: Differential expression of ENaC, CFTR and NHE in vas deferens under testosterone influence indicated the important role of these transporters in creating optimal fluid microenvironment that is essential for preserving male fertility.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA “on” and “off” motifs. Proteomics analysis was performed on AGS cell pre‐infection and postinfection with H. pylori oipA “on” and “off” strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down‐regulated postinfection with oipA “off” strains comparing to oipA “on” strains. Furthermore, oipA “off” and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell‐cycle arrest than oipA “on” strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA “on” strains predominates.