Erythropoietin promotes myocardial infarction repair in mice by improving the function of Sca-1+ stem cells / 生理学报

Myocardial infarction (MI) is one of the leading causes of death in the world. With the improvement of clinical therapy, the mortality of acute MI has been significantly reduced. However, as for the long-term impact of MI on cardiac remodeling and cardiac function, there is no effective prevention and treatment measures. Erythropoietin (EPO), a glycoprotein cytokine essential to hematopoiesis, has anti-apoptotic and pro-angiogenetic effects. Studies have shown that EPO plays a protective role in cardiomyocytes in cardiovascular diseases, such as cardiac ischemia injury and heart failure. EPO has been demonstrated to protect ischemic myocardium and improve MI repair by promoting the activation of cardiac progenitor cells (CPCs). This study aimed to investigate whether EPO can promote MI repair by enhancing the activity of stem cell antigen 1 positive stem cells (Sca-1+ SCs). Darbepoetin alpha (a long-acting EPO analog, EPOanlg) was injected into the border zone of MI in adult mice. Infarct size, cardiac remodeling and performance, cardiomyocyte apoptosis and microvessel density were measured. Lin- Sca-1+ SCs were isolated from neonatal and adult mouse hearts by magnetic sorting technology, and were used to identify the colony forming ability and the effect of EPO, respectively. The results showed that, compared to MI alone, EPOanlg reduced the infarct percentage, cardiomyocyte apoptosis ratio and left ventricular (LV) chamber dilatation, improved cardiac performance, and increased the numbers of coronary microvessels in vivo. In vitro, EPO increased the proliferation, migration and clone formation of Lin- Sca-1+ SCs likely via the EPO receptor and downstream STAT-5/p38 MAPK signaling pathways. These results suggest that EPO participates in the repair process of MI by activating Sca-1+ SCs.

Knocking-down Synaptotagmin 1 Attenuated Colitis via Suppressing the IL-6/STAT3 Signaling Pathway / 中国生物化学与分子生物学报

Synaptotagmin 1 (Sytl) is a member of the Synaptotagmin family and plays a role in neurotransmitter vesicle transport and exoeytosis. It has been reported that Sytl appears to be expressed in the intestinal epithelium, but the biological function of Sytl in colitis remains poorly understood. This study aimed to investigate the effects of Sytl in the inflammatory response and intestinal epithelial regeneration in colitis using Sytl transgenic mice and dextran sulfate sodium (DSS)-induced ulcerative colitis mode. qRT-PCR and Western blotting were employed to analyze the dynamic changes of Sytl in colitis. H&E staining, immunostaining and Western blotting were used to explore the roles of Sytl in the inflammatory response and in the regeneration and repair of intestinal epithelium in colitis. The results showed that the expression level of Sytl was indeed high in the colonic epithelium of wild-type mice and the intestinal epithelial cells of the adjacent tissues of colorectal cancer patients. Consistently, DSS-induced inflammation progressively resulted in marked upregulation of Sytl in the colon (P<0.01). In DSS-induced colitis, both the body weight loss and colonic shortening were dampened in Sytl loss-of-function mice compared with the control group (P < 0.05), while the number of regenerated crypts and Ki67 proliferating cells were also increased (P<0.01). Additionally, there were less infiltration of CD45 immune cells and F 4/80 macrophages and the expression of pro-inflammatory cytokines IL-6, TNFα and I L l-β, which were related with the severity of inflammation in the inflammatory bowel disease (I B D), were significantly decreased after Sytl deletion (P<0.05). Immunohistochemistry staining and Western blotting results further showed that IL-6 and p-STAT3 was significantly downregulated in Sytl knockdown mice (P<0.05). Taken together, these results suggested that knocking-down of Sytl may improve colitis by inhibiting the IL6/STAT3 signaling pathway.

Recent advances in the biotoxicity of silica nanoparticles / 医学研究生学报

Silica Nanoparticles (SiNPs) is widely used in many fields including antibacterial agent, molecular probe and drug delivery forits special physicochemical properties. Recently, the biosecurity of nano-materials has become a hot spot of research in toxicology due to special structure and functional activeness of nano-materials. This paper briefly summarized recent researchreports at home and abroadto review the toxicity of SiNPs on cells and animals, the factors for influencing the toxicity of SiNPs and the mechanisms underlying SiNPs biotoxicity, aiming to provide references for the development, application and biosecurity of SiNPs.

Research Advances in Sympathetic Remodeling after Myocardial Infarction and Its Significance in Forensic Science / 法医学杂志

Sympathetic remodeling after myocardial infarction is presented as denervation, sympathetic nerve sprouting and sympathetic hyperinnervation, and is closely related to ventricular tachyarrhythmias and even sudden cardiac death at convalescence in patients with myocardial infarction. This article reviews the anatomic structure, morphology and functional remodeling of cardiac sympathetic nerve, as well as its role in healed myocardial infarction identification, which may provide references for forensic research.

A preliminary experimental study on the cardiac toxicity of glutamate and the role of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor in rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Monosodium L-glutamate (MSG) is a food flavour enhancer and its potential harmfulness to the heart remains controversial. We investigated whether MSG could induce cardiac arrhythmias and apoptosis via the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor.</p><p><b>METHODS</b>Myocardial infarction (MI) was created by ligating the coronary artery and ventricular arrhythmias were monitored by electrocardiogram in the rat in vivo. Neonatal rat cardiomyocytes were isolated and cultured. Cell viability was estimated by 3-(4,5)-dimethylthiahiazo(-z-yl)-3,5-di-phenytetrazoliumromide (MTT) assay. Calcium mobilization was monitored by confocal microscopy. Cardiomyocyte apoptosis was evaluated by acridine orange staining, flow cytometry, DNA laddering, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting.</p><p><b>RESULTS</b>MSG (i.v.) decreased the heart rate at 0.5 g/kg and serious bradycardia at 1.5 g/kg, but could not induce ventricular tachyarrhythmias in normal rats in vivo. In rats with acute MI in vivo, however, MSG (1.5 g/kg, i.v.) induced ventricular tachyarrhythmias and these arrhythmias could be prevented by blocking the AMPA and N-methyl-d-aspartate (NMDA) receptors. Selectively activating the AMPA or NMDA receptor induced ventricular tachyarrhythmias in MI rats. At the cellular level, AMPA induced calcium mobilization, oxidative stress, mitochondrial dysfunction and apoptosis in cultured cardiomyocytes, especially when the AMPA receptor desensitization were blocked by cyclothiazide. The above toxic cellular effects of AMPA were abolished by AMPA receptor blockade or by H2O2 scavengers.</p><p><b>CONCLUSIONS</b>MSG induces bradycardia in normal rats, but triggers lethal tachyarrhythmias in myocardial infarcted rats probably by hindering AMPA receptors. AMPA receptor overstimulation also induces cardiomyocyte apoptosis, which may facilitate arrhythmia.</p>

Development of an ECG signals analysis service system based on B/S / 中国医疗器械杂志

An online ECG signals analysis service system based on the network has been established and is introduced in this paper which integrates the advantages of the network, database and ECG analysis tools, providing on-line ECG signal analysis service. Users with the knowledge of general operation of a browser, can process the ECG data and get a real-time display of analysis results.

Short time ECG signal analysis based on the reconstruction of phase space / 中国医疗器械杂志

Based on the reconstruction of two-dimension phase space of time series of short ECG signals, the variation of the strange attractor geometry is described and two indices, VMI and VAI, are derived in this paper. The two indices can distinguish clearly the ECG signals of sinus rhythm, tachycardia and ventricular fibrillation. Stable results of VMI and VAI can be obtained by analyzing ECG signals of several seconds. They are expected to be used in the development of medical instruments for a fast realtime display of analysis results.