Protective effect of diltiazem on myocardial ischemic rats induced by isoproterenol.

The aim of the present study was to analyze the effect of diltiazem on myocardial fibrosis and remodeling of connexin43 (Cx43) in myocardial ischemic rats and mechanisms underlying these processes. A total of 36 Sprague­Dawley rats were randomly allocated into three groups (control, isoproterenol and isoproterenol with diltiazem). The myocardial ischemic model was established by 5 mg/kg/day isoproterenol administration for 7 days, and the diltiazem group received 25 mg/kg/day diltiazem for 4 weeks. Following the treatment, paraffin sections were prepared to observe microstructural changes and to evaluate the concentration of Ca2+ in myocardium. The expression of transforming growth factors­ß1 (TGF­ß1), mothers against decapentaplegic homologues (Smad)2 and 7 and Cx43, were analyzed by reverse transcription-quantitative polymerase chain reaction and western blotting. The percentage Cx43 expression in intercalated disks was evaluated using immunohistochemistry. Fibrosis did not differ significantly between the control and the diltiazem­treated group. The concentration of Ca2+ increased in the myocardium of model rats. The expression of Smad7 and Cx43 was decreased in the rat model, while the expression of TGF­ß1 and Smad2 was increased. There was a significant decrease in the relative abundance of intercalated disk Cx43 in the model group. The results of the present study suggest that diltiazem may serve a protective role during remodeling of myocardial ischemia, especially in fibrosis and Cx43 remodeling.

Exposure to a chronic high-fat diet promotes atrial structure and gap junction remodeling in rats.

Obesity has been demonstrated to be linked to atrial fibrillation (AF) with atrial enlargement and tissue fibrosis. Long-term high calorie intake is the main reason for the prevalence of obesity. To investigate the possible causes of AF, such as chronic high-fat diet (HFD), and to identify the underlying mechanisms, the present study analyzed a variety of structural and gap junctional electrophysiological alterations in the atria of female rats fed an HFD. After consistent HFD feeding of female rats for 12 weeks, hematoxylin and eosin (H&E) and Masson's staining, RT-qPCR, western blotting, immunofluorescence and TUNEL staining were performed. In our study, approximately 3/5 of the HFD-fed rats (HFD-OB, n=13) displayed a significant increase in body weight, while the other 2/5 did not (HFD-NOB, n=8). In addition, the atrial weight of the HFD-OB and HFD-NOB rats was markedly heavier, as compared to the rats fed a normal diet (CT, n=20). According to the plasma lipid levels, both HFD-OB and HFD-NOB rats exhibited dyslipidemia. Furthermore, H&E staining revealed broadened interstitial space and myocyte disarray in atria of the HFD-fed rats (i.e., HFD-OB and HFD-NOB rats). Expression levels of atrial fibrosis relevant factors, transforming growth factor-ß1 and matrix metalloproteinase-2, were significantly upregulated in the HFD-fed rat atria. In addition, we found a gap junction remodeling with distinct alterations in expression and distribution of connexin 40 (Cx40) and Cx43 in the HFD-fed rat atria. Moreover, a modest increase in apoptotic cell death in both the HFD-OB and HFD-NOB rat atria was detected. Taken together, our findings demonstrated that the impact of chronic HFD on atria displayed in the diet-induced obese rats was observed in HFD-fed rats in the absence of obesity as well.

Fresh Garlic Extract Enhances the Antimicrobial Activities of Antibiotics on Resistant Strains in Vitro.

BACKGROUND: Infections caused by strains with multi-drug resistance are difficult to treat with standard antibiotics. Garlic is a powerful remedy to protect against infections of many bacteria, fungi and viruses. However, little is known about the potentials of fresh garlic extract (FGE) to improve the sensitivity of multi-drug resistant strains to antibiotics. OBJECTIVES: In this study, we used the disk diffusion method to investigate the antimicrobial activities of FGE and the combination of antibiotics with FGE, on methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Candida albicans, to evaluate the interactions between antibiotics and FGE. MATERIALS AND METHODS: Clinical isolates were isolated from clinical specimens obtained from the inpatients at the First Affiliated Hospital of Xi'an Jiaotong University Health Science Center. The isolates consisted of MRSA, (n = 30), C. albicans (n = 30) and P. aeruginosa (n = 30). Quality control for CLSI (Clinical and Laboratory Standards Institute) disk diffusion was performed using S. aureus ATCC®25923, C. albicans ATCC®90028 and P. aeruginosa ATCC®27853. The 93 microorganisms were divided into four groups in a factorial design: control (deionized water), FGE, antibiotics without FGE, and antibiotics with FGE. Next, antibacterial activity was evaluated by measuring the diameter of inhibition zones according to performance standards for antimicrobial susceptibility testing of the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS). RESULTS: Fresh garlic extract displayed evident inhibition properties against C. albicans and MRSA, yet weak inhibition properties against P. aeruginosa. Additionally, FGE showed the potential to improve the effect of antibiotics on antibiotic resistant pathogens. The synergism of fluconazole and itraconazole with FGE on C. albicans yielded larger sized inhibition zones compared with fluconazole and itraconazole without FGE (P < 0.01). The factorial analysis represents intense positive interaction effects (P < 0.01). The synergism of cefotaxime and ceftriaxone with FGE on P. aeruginosa yielded larger sized inhibition zones than cefotaxime and ceftriaxone without FGE (P < 0.01). The factorial analysis represents intense positive interaction effects (P < 0.01). CONCLUSIONS: The results suggest that FGE can improve the antibiotic sensitivity of these pathogens to some antibiotics.

Review of melamine scandal: still a long way ahead.

In September 2008, in China, tens of thousands of children were hospitalized, several even died, as a result of infant-formula milk adulterated with a synthetic chemical compound, melamine, and in the next few months, this crisis became the focus of attention worldwide. Although there are a number of articles about melamine toxicity on different species of animals, the long-term effect of melamine on humans is still unknown. Besides, several recent in vitro studies indicated that melamine can damage cells of other parts of the body, including the central nervous system, breaking the previous view that melamine toxicity is limited to the urinary system. Hence, we strongly recommend a long-term follow-up for the overall health status of the victims, not confined to kidneys, to minimize the potential toxic effects in their later life; and research to study the specific mechanism of melamine should be encouraged.

The effect of exogenous melamine on rat hippocampal neurons.

Rat hippocampal neurons in culture medium were exposed to different concentrations of melamine. By examining the morphology of cells detected with acridine orange staining, different changes of fluorescences of Ca²âº observed with Fluo3, and caspase-3 activity assayed with optical density by enzyme linked immunosorbent assay kit, we found the effect of melamine on hippocampal neurons. Pathologic changes happened in hippocampal neurons, and there seemed to be insoluble metabolites in most of the cells with 312 µg/mL melamine stimulated for 12 hours. Then, we tested the Ca²âº fluorescences of the cells above. The free intracellular Ca²âº concentrations were measured using the fluorescent dye Fluo3. The average fluorescence of Ca²âº in hippocampal neurons stimulated by 312 µg/mL melamine (55.43 ± 3.54) was higher than the normal ones (6.94 ± 0.14). Besides, caspase-3 activity of hippocampal neurons after being challenged with melamine was higher than that of normal ones in the mass. From the above conclusions, melamine did induce damnification to hippocampal neurons, probably in the way of inducing cells to undergo apoptotic processes and disrupting the homeostasis of Ca²âº. Our experimental results disproved some viewpoints that not melamine alone, but melamine and cyanuric acid in combination could cause damage in toxicological studies and provided compelling evidence that low levels of melamine exposure may also represent a health risk to nerves, in opposition to the idea that damage of melamine and cyanuric acid in combination were limited to the kidneys.