Outer membrane protein A (OmpA) is a potential virulence factor of Vibrio alginolyticus strains isolated from diseased fish

Vibrio alginolyticus is one of the most serious causative agents of diseases in cultured marine fish and shellfish. However, the characteristics of virulence factors in pathogenic V. alginolyticus are poorly known. To gain insight into fish diseases caused by V. alginolyticus, we carried out two-dimensional gel electrophoresis (2-DE) combined with MALDI-TOF mass spectrometry to identify uniquely expressed proteins in the disease-causing V. alginolyticus. V. alginolyticus strains were isolated from marine environments and diseased fish obtained from southern Thailand. We identified seven unique proteins in the disease-causing V. alginolyticus strain. Among those, the outer membrane protein A (OmpA) had the strongest expression. Therefore, the function of this protein was further analysed. To investigate the role of OmpA protein, an in-frame deletion mutant of ompA was constructed using the homologous recombination method. Although the ompA mutant V. alginolyticus strain (ΔompA) grew normally, the mutant exhibited a significant defect in the swarming ability and the biofilm formation. Furthermore, Galleria mellonella larvae injected with the mutant bacteria had a significantly greater survival percentage than those injected with the wild-type strain, demonstrating that OmpA protein is required for the pathogenicity of V. alginolyticus. Together, this study suggests a potential target for vaccine development against pathogenic V. alginolyticus strain.

Proteomic profiling of Stemona alkaloids production response to chitosan elicitor

The study purposed to investigate the protein expression of Stemona alkaloids biosynthesis response to chitosan elicitor by 2D gel electrophoresis. The total proteins extraction of Stemona roots were performed for comparison with the control and chitosan treatments. It was found that 15 out of 150 protein spots exhibited different expression between control and chitosan culture treatment. The identified 15 protein spots were subjected to amino acid sequencing and two proteins appeared interesting for examining Stemona alkaloids biosynthesis. After treated with chitosan, glutathione S-transferase became down-regulated while heat shock protein up-regulated in relation to the control treatment. These proteins may play roles in alkaloids biosynthesis via plant defense metabolism from the presumptions that chitosan might weaken the detoxifying function of glutathione S-transferase, then, heat shock protein is probably produced to signal for tissue protection mechanism. Thus, Stemona alkaloids may be responsive to this stress.

Bioequivalence study of generic amlodipine in healthy Thai male volunteers

SUBJECTS, MATERIAL AND METHODS

To determine the bioequivalence of 10 mg generic amlodipine in healthy male volunteers, the reference and the test formulations were administered as a single oral dose after overnight fasting in a crossover study separated by 2-week washout interval. After dosing, serial blood samples were collected for a period of 144 h. Plasma amlodipine concentrations were determined by LC-MS/MS and the pharmacokinetic parameters were analyzed by non-compartmental analysis.

RESULTS

The mean elimination half-life (t1/2) for the test (40 h) and the reference (44 h) were within the values previously reported. The rate of absorption reflected by tmax had a difference of -0.33 h, with a 90% CI of (-1.52)-0.85 (acceptable range +/- 1.3). Although the tmax of the test (5 h) was faster than the reference (6 h), the mean (90% CI) of the AUC(0-infinity) and Cmax ratios Test/Reference were 0.91 (0.87-0.97) and 1.01 (0.93-1.09), respectively. These values were within the range of 0.80-1.25, thus, the study demonstrated the bioequivalence of the 2 formulations.

Dual effects of quercetin on contraction in cardiac and skeletal muscle preparations

The effects of quercetin, a plant flavonoid, on contraction in cardiac and skeletal muscle preparations were examined. Higher concentrations of quercetin increased mean arterial blood pressure in anesthetized rats. Quercetin showed positive inotropic action on spontaneous contraction in a dose-dependent manner in isolated rat atria. Quercetin prevented the negative inotropism evoked by acetylcholine in isolated rat atria. On the other hand, quercetin inhibited the twitch contraction in isolated rat hemidiaphragm muscles. The addition of Ca2+ to extracellular medium recovered the inhibitory effects of twitch contraction in Ca2+-free medium but did not prevent the inhibitory effects of twitch contraction in Ca2+-free medium containing quercetin. The present results suggest that quercetin have a positive inotropic action in cardiac muscle but inhibitory effects on contraction in skeletal muscle.