Effect of rosiglitazone on cardiac electrophysiology, infarct size and mitochondrial function in ischaemia and reperfusion of swine and rat heart

Rosiglitazone, a peroxisome proliferator-activated receptor γ agonist, has been used to treat type 2 diabetes. Despite debates regarding its cardioprotection, the effects of rosiglitazone on cardiac electrophysiology are still unclear. This study determined the effect of rosiglitazone on ventricular fibrillation (VF) incidence, VF threshold (VFT), defibrillation threshold (DFT) and mitochondrial function during ischaemia and reperfusion. Twenty-six pigs were used. In each pig, either rosiglitazone (1 mg kg(-1)) or normal saline solution was administered intravenously for 60 min. Then, the left anterior descending coronary artery was ligated for 60 min and released to promote reperfusion for 120 min. The cardiac electrophysiological parameters were determined at the beginning of the study and during the ischaemia and reperfusion periods. The heart was removed, and the area at risk and infarct size in each heart were determined. Cardiac mitochondria were isolated for determination of mitochondrial function. Rosiglitazone did not improve the DFT and VFT during the ischaemia-reperfusion period. In the rosiglitazone group, the VF incidence was increased (58 versus 10%) and the time to the first occurrence of VF was decreased (3 ± 2 versus 19 ± 1 min) in comparison to the vehicle group (P < 0.05). However, the infarct size related to the area at risk in the rosiglitazone group was significantly decreased (P < 0.05). In the cardiac mitochondria, rosiglitazone did not alter the level of production of reactive oxygen species and could not prevent mitochondrial membrane potential changes. Rosiglitazone increased the propensity for VF, and could neither increase defibrillation efficacy nor improve cardiac mitochondrial function.     

Calcium channels and iron uptake into the heart

Iron overload can lead to iron deposits in many tissues,particularly in the heart.It has also been shown to be associated with elevated oxidative stress in tissues.Elevated cardiac iron deposits can lead to iron overload cardiomyopathy,a condition which provokes mortality due to heart failure in iron-overloaded patients.Currently,the mechanism of iron uptake into cardiomyocytes is still not clearly understood.Growing evidence suggests L-type Ca2+channels(LTCCs)as a possible pathway for ferrous iron(Fe2+)uptake into cardiomyocytes under iron overload conditions.Nevertheless,controversy still exists since some findings on pharmacological interventions and those using different cell types do not support LTCC’s role as a portal for iron uptake in cardiac cells.Recently,T-type Ca2+channels (TTCC)have been shown to play an important role in the diseased heart.Although TTCC and iron uptake in cardiomyocytes has not been investigated greatly,a recent finding indicated that TTCC could be an important portal in thalassemic hearts.In this review,comprehensive findings collected from previous studies as well as a discussion of the controversy regarding iron uptake mechanisms into cardiomyocytes via calcium channels are presented with the hope that understanding the cellular iron uptake mechanism in cardiomyocytes will lead to improved treatment and prevention strategies,particularly in iron-overloaded patients.     

Case reports of neuro-Chikungunya in southern Thailand

There has been a recent increase in reports of neurologic complications as major causes of morbidity and mortality in chikungunya virus infection. As a part of 2004-2009 global outbreaks, an unprecedented large chikungunya epidemic occurred in Southern Thailand during 2008-2009 in which 49,069 cases were reported. During this period, we encountered two patients with meningoencephalitis and another patient with myeloneuropathy among 1,018 cases diagnosed as chikungunya in our hospital. The clinical pictures are presented and the key points are used to recognize and differentiate chikungunya from Japanese encephalitis virus, dengue virus, and herpesvirus infections, which are more common causes of meningoencephalitis and myelitis in this region.     

Heart rate variability in beta‐thalassemia patients

Background: Cardiac failure remains the major cause of death in beta‐thalassemia major (TM). Reduced heart rate variability (HRV) is associated with a higher risk of arrhythmias after myocardial infarction and heart failure. We evaluated HRV in TM patients and its relationship with hemodynamics and echocardiographic parameters during a 6‐month follow‐up. Methods: Thirty‐four TM patients (19 ± 10 yr) and 20 healthy subjects (17 ± 6 yr) were evaluated. Hematologic, biochemical, echocardiographic and HRV parameters were determined at entry and at 6‐month follow‐up. Time and frequency domain HRV parameters were analyzed from 24‐h recorded electrocardiograms. All TM patients received blood transfusion and chelation therapy. Results: Both time and frequency domain HRV parameters were markedly reduced in TM patients, compared to the control. The significantly improved HRV was seen in correlation with higher hemoglobin (Hb) level when compared within TM group at different time point. No correlation was seen between HRV and serum ferritin, reactive oxygen species (ROS) and non‐transferrin bound iron (NTBI). Conclusion: HRV is depressed in TM patients. HRV was significantly correlated with Hb level, suggesting that anemia greatly influences the cardiac autonomic balance.     

Partial characterization of a novel bacteriophage of Vibrio harveyi isolated from shrimp culture ponds in Thailand

A bacteriophage was isolated together with Vibrio harveyi (VH) 1114 a from a black tiger shrimp-rearing pond in Thailand. By negative staining transmission electron microscopy (TEM), the phage had an icosahedral head (diameter 60-62 nm), a rigid, non-contractile tail (9-10 nm x 100-120 nm) without a collar or terminal fibers and a genome of double stranded DNA of approximately 80 kb as determined by analysis of restriction enzyme digestion fragments. Since these features would place it in the family Siphoviridae, it was tentatively named V. harveyi siphoviridae-like phage or VHS1. VHS1 could also infect two VH reference strains LMD 22.30 and LMD 80.33 (=ATCC 14126) but yielded smaller plaques than with VH1114. The phage tolerated temperatures as high as 60 degrees C for up to 2h and overnight exposure to a broad range of pH. VHS1 lysogens of VH1114 were unstable, contained unaltered VHS1 DNA, were immune to VHS1 lysis and spontaneously released VHS1 in liquid cultures. Approximately 20 kb of the genome has been sequenced and deposited at GenBank but it mostly showed no significant homology with existing sequences in the database.     

Eryngium foetidum suppresses inflammatory mediators produced by macrophages

Objective: This study assessed anti-inflammatory and antioxidant activities of E. foetidum leaf extract on LPS-activated murine macrophages. Methods: RAW264.7 cells were pretreated with or without E. foetidum extract for 1 h prior to incubation with LPS for 24 h. Anti-inflammatory activity was evaluated with reference to iNOS, COX-2, TNF-α and IL-6 gene expression. In addition, NO and intracellular ROS generation were determined by Griess method and fluorescence intensity and activation of MAPKs and IkB by Western blotting. Results: Prior treatment with E. foetidum leaf extract inhibited elevation of IL-6, TNF-α, iNOS and COX-2, together with their cognate mRNAs in a dose-dependent manner. NO and intracellular ROS contents were similarly reduced. These effects were due to inhibition of LPS-induced phosphorylation of JNK and p38 as well as IkB. E. foetidum ethanol extract were shown to contain lutein, β-carotene, chlorogenic acid, kaempferol and caffeic acid, compounds known to exert these bioactive properties. Conclusions: E. foetidum leaf extract possesses suppressive effects against pro-inflammatory mediators. Thus, E. foetidum has a high potential to be used as a food supplement to reduce risk of cancer associated with inflammation.     

A rapid,simple, and sensitive loop-mediated isothermal amplification method to detect toxigenic Vibrio cholerae in rectal swab samples

Loop-mediated isothermal amplification (LAMP) method was designed for clinical diagnosis of Vibrio cholerae carrying the ctxA gene. The detection limits of the method were 5 fg of purified genomic DNA/reaction and 0.54 CFU/reaction. The method was applied to rectal swab samples from cholera patients and healthy volunteers (19 subjects each) and yielded the same results as the “gold standard” culture method, while the polymerase chain reaction-based method failed to detect V. cholerae in 8 of the positive samples. Direct application of this LAMP method without precultivation enabled the rapid detection of 5 asymptomatic carriers from rectal swabs of 21 household contacts of cholera patients. This LAMP method could be a sensitive, specific, inexpensive, and rapid detection tool for V. cholerae carrying the ctxA gene in the clinical laboratory and in the field.     

Prevalence and Correlates of Sexual Behaviors Among Karen Villagers in Northern Thailand

A cross-sectional survey was conducted in two mountainous villages of the Karen, a major ethnic minority in Thailand. The participants were 566 villagers aged 15–54 years (371 in Village A, 195 in Village B; response rate=81.9%). Premarital/extramarital sex was experienced by 10–20% of the sexually active respondents and sex with a female sex worker (FSW) by 12.6% of males. Premarital sex was independently associated with being a Christian and occupational experience in town; extramarital sex was associated with Village A and drug use; sex with a FSW was associated with being unmarried, a nonfarmer, and occupational experience in town. Approximately 80% of the married participants never used a condom with their spouse, and nearly one-third never did so with a boy/girlfriend or a FSW. A history of sexually transmitted infections (STIs) was associated with sex with a FSW. These findings suggest that nontraditional sexual practices are prevalent and could potentially threaten Karen communities with the spread of HIV.