Vasorelaxant properties of Vernonia amygdalina ethanol extract and its possible mechanism

Context: Vernonia amygdalina Del. (VA) (Asteraceae) is commonly used to treat hypertension in Malaysia.

Objective: This study investigates the vasorelaxant mechanism of VA ethanol extract (VAE) and analyzes its tri-step FTIR spectroscopy fingerprint.

Materials and methods: Dried VA leaves were extracted with ethanol through maceration and concentrated using rotary evaporator before freeze-dried. The vasorelaxant activity and the underlying mechanisms of VAE using the cumulative concentration (0.01–2.55?mg/mL at 20-min intervals) were evaluated on aortic rings isolated from Sprague Dawley rats in the presence of antagonists.

Results: The tri-step FTIR spectroscopy showed that VAE contains alkaloids, flavonoids, and saponins. VAE caused the relaxation of pre-contracted aortic rings in the presence and absence of endothelium with EC₅₀ of 0.057?±?0.006 and 0.430?±?0.196?mg/mL, respectively. In the presence of Nω-nitro-l-arginine methyl ester (EC₅₀ 0.971?±?0.459?mg/mL), methylene blue (EC₅₀ 1.203?±?0.426?mg/mL), indomethacin (EC₅₀ 2.128?±?1.218?mg/mL), atropine (EC₅₀ 0.470?±?0.325?mg/mL), and propranolol (EC₅₀ 0.314?±?0.032?mg/mL), relaxation stimulated by VAE was significantly reduced. VAE acted on potassium channels, with its vasorelaxation effects significantly reduced by tetraethylammonium, 4-aminopyridine, barium chloride, and glibenclamide (EC₅₀ 0.548?±?0.184, 0.158?±?0.012, 0.847?±?0.342, and 0.304?±?0.075?mg/mL, respectively). VAE was also found to be active in reducing Ca²⁺ released from the sarcoplasmic reticulum and blocking calcium channels.

Conclusions: The vasorelaxation effect of VAE involves upregulation of NO/cGMP and PGI₂ signalling pathways, and modulation of calcium/potassium channels, and muscarinic and β₂-adrenergic receptor levels.     

Polychlorinated Biphenyls Disrupt Intestinal Integrity via NADPH Oxidase-Induced Alterations of Tight Junction Protein Expression

Background

Polychlorinated biphenyls (PCBs) are widely distributed environmental toxicants that contribute to numerous disease states. The main route of exposure to PCBs is through the gastrointestinal tract; however, little is known about the effects of PCBs on intestinal epithelial barrier functions.

Objective

The aim of the present study was to address the hypothesis that highly chlorinated PCBs can disrupt gut integrity at the level of tight junction (TJ) proteins.

Methods

Caco-2 human colon adenocarcinoma cells were exposed to one of the following PCB congeners: PCB153, PCB118, PCB104, and PCB126. We then assessed NAD(P)H oxidase (NOX) activity and expression and the barrier function of Caco-2 cells. In addition, the integrity of intestinal barrier function and expression of TJ proteins were evaluated in C57BL/6 mice exposed to individual PCBs by oral gavage.

Results

Exposure of Caco-2 cells to individual PCB congeners resulted in activation of NOX and increased permeability of fluorescein isothiocyanate (FITC)-labeled dextran (4 kDa). Treatment with PCB congeners also disrupted expression of TJ proteins zonula occludens-1 (ZO-1) and occludin in Caco-2 cells. Importantly, inhibition of NOX by apocynin significantly protected against PCB-mediated increase in epithelial permeability and alterations of ZO-1 protein expression. Exposure to PCBs also resulted in alterations of gut permeability via decreased expression of TJ proteins in an intact physiological animal model.

Conclusions

These results suggest that oral exposure to highly chlorinated PCBs disrupts intestinal epithelial integrity and may directly contribute to the systemic effects of these toxicants.     

Specific detection of fungal pathogens by 18S rRNA gene PCR in microbial keratitis

Background  

The sensitivity and specificity of 18S rRNA polymerase chain reaction (PCR) in the detection of fungal aetiology of microbial keratitis was determined in thirty patients with clinical diagnosis of microbial keratitis.     

Flicking technique for microencapsulation of cells in calcium alginate leading to the microtissue formation

Microbeads have wide applications in biomedical engineering field that include drug delivery, encapsulation of biomolecules, tissue padding and tissue regeneration. In this paper, we report a simple, yet efficient, flicking technique to produce microcapsules of calcium alginate at a narrow distribution of size. The system consists of an infusion pump and a customised flicker that taps the syringe needle for dispersing microcapsules of sodium alginate that polymerised in the calcium chloride solution. The flow rate of the syringe pump and the velocity of the flicker were studied to achieve a well controlled and tunable size distribution of microbeads ranging from 200 to 400?μm. At a flow rate of 4?μl/min and flicking rate of 80?rpm, a narrow size distribution of microbeads were produced. Via this technique, HaCaT cells were encapsulated in calcium alginate microbeads that grown into microtissues with a size ranging from 100 to 300?μm after two weeks of culture. These microtissues could be potentially useful for pharmacological application.     

MAGNOLOL REDUCES INFARCT SIZE AND SUPPRESSES VENTRICULAR ARRHYTHMIA IN RATS SUBJECTED TO CORONARY LIGATION

1. Magnolol is an active component of Magnolia officinalis. It is 1000-times more potent than α-tocopherol in inhibiting lipid peroxidation in rat heart mitochondira. In the present study, the in vivo antiarrhythmic and anti-ischaemic effects of magnolol in coronary ligated rats were investigated. 2. Male Sprague-Dawley rats were anaesthetized with urethane. Magnolol, at dosages of 10^?7, 10^?8 and 10^?9 g/kg, was adminstered intravenously 15 min before ligation of the coronary artery. 3. The incidence and duration of ventricular tachycardia and ventricular fibrillation during 30 min coronary ligation were significantly reduced by magnolol. Ventricular arrhythmias during 10 min reperfusion after the relief of coronary ligation were also reduced. 4. In rats subjected to 4h coronary ligation, 10^?7 and 10^?8 g/kg magnolol significantly reduced infarct size. 5. We conclude that magnolol may protect the myocardium against ischaemic injury and suppress ventricular arrhythmia during ischaemia and reperfusion.     

携带LacZ的腺病毒载体在牵引骨痂局部转染成纤维细胞和成骨细胞的表达

目的:利用小鼠胫骨牵引成骨动物模型,在牵引成骨过程中局部给予携带了LacZ的腺病毒载体后观察其表达情况,以探讨基因治疗促进骨折愈合的可行性。方法:实验于2004-10/2006-01在中南大学湘雅三医院完成。①实验分组:取雄性8周龄CD-1小鼠20只,随机数字表法分为实验组和对照组,每组各10只。②实验方法:所有小鼠接受左胫骨中上段骨干横行截骨安置特制延长外固定架,胫骨牵引过程包括5d静止期,10d牵引期,牵引速率为0.1mm/次,2次/d,共0.2mm/d。牵引期第7天实验组牵引骨痂局部注射5μL携带了LacZ的腺病毒载体,对照组局部注入等量未含LacZ腺病毒液。③实验评估:注射后第3天麻醉后杀取动物,采集左胫骨标本,分别作组织学检查和组织化学分析。结果:纳入小鼠20只,均进入结果分析。在牵引第10天,牵引骨痂中纤维间区形成,两端的新生骨由骨折两端中心生长延伸。骨髓腔内外可见大量新生骨形成。X-Gal底物染色显示,在实验组新生骨组织内可见大量细胞呈阳性染色;而对照组未发现阳性染色细胞。结论:在牵引成骨过程中,骨痂局部注射携带LacZ的腺病毒,能成功转染局部的成纤维细胞及成骨细胞,并表达LacZ基因,为临床应用基因治疗促进骨牵引延长或骨折愈合提供可行性。     

壳聚糖基因转移载体在关节软骨细胞中表达的定量分析

目的:壳聚糖作为基因转移的载体存在着转染效率的问题。实验对壳聚糖介导的报告基因增强型绿色荧光蛋白在关节软骨细胞中的基因表达效率进行定量分析。方法:实验于2005-09/2006-06在健康科学研究所骨科细胞与分子生物学实验室完成。①实验材料:壳聚糖购自Sigma公司;荧光质粒pEGFP-C3为Clontech公司产品;成年新西兰白兔2只。②实验分组:实验分为空白对照组(软骨细胞不转染)、裸质粒pEGFP-C3对照组和壳聚糖-pEGFP转染组。③实验过程:软骨细胞取自新西兰白兔的关节软骨。以多聚糖壳聚糖为载体,荧光质粒pEGFP-C3作为报告基因,利用高速震荡法制备壳聚糖-pEGFP超微颗粒,用制备的携带不同量(1,2,3,4,5μg)DNA的壳聚糖-pEGFP超微颗粒对软骨细胞进行体外转染。裸质粒pEGFP-C3对照组加入等量的DNA。④实验评估:光镜观察软骨细胞及壳聚糖-DNA超微颗粒的形态;荧光显微镜观察不同条件下绿色荧光蛋白的表达并进行定量分析。结果:①光镜下观察空白对照组,裸质粒pEGFP-C3对照组及壳聚糖-pEGFP转染组,软骨细胞形态均呈多角形,贴壁生长,增长活跃,转染组软骨细胞周围黏附有大量的球形小颗粒;制备的壳聚糖-DNA超微颗粒大小均匀,直径大约在150～300nm。②在壳聚糖-pEGFP超微颗粒转染的软骨细胞中观察到有绿色荧光蛋白的表达,且DNA含量在1～5μg范围内,细胞的转染效率和表达效率随颗粒包被的DNA量的增加而增加。结论:壳聚糖在关节基因转移中具有一定的体外DNA导入的功能,且随壳聚糖-pEGFP超微颗粒所携带的DNA量的增加转染效率和表达效率增加,经进一步研究它有望成为一种关节体内基因导入的有效工具。     

光生物调节及糖皮质激素治疗类固醇肌病的前景

目的:综述糖皮质激素引起类固醇肌病的机制及其传统治疗方法和具有前景的光生物调节疗法。资料来源:应用计算机检索Medline、Ovoid和Springer1970/2007与糖皮质激素类固醇肌病及其疗法相关的文章,检索词“glucocorticoid,myopathy,therapy,low intensity laser therapy”,并限定文章语言为English。同时在中国全文数据库中检索,检索词“糖皮质激素,类固醇肌病”,并限定文章语言为中文。资料选择:对资料进行初审,纳入标准:糖皮质激素引起类固醇肌病的机制及其主要疗法的文献。排除标准:重复性研究。资料提炼:共收集到133篇相关文献。在选择和分析的基础上,排除重复或类似研究,最终提炼出48篇文献进行分类整理。资料综合:长期使用或大量使用糖皮质激素可以导致类固醇肌病的发生。通过糖皮质激素受体介导的信号转导,糖皮质激素可以正向或者负向调节相关基因的表达,从而产生如加快蛋白降解和减慢蛋白合成等相关效应。细胞模型或动物模型的实验表明,糖皮质激素可以从对骨骼肌能量代谢、氨基酸平衡、蛋白质代谢和成肌等方面的干扰而破坏骨骼肌细胞的内稳态,这可能是糖皮质激素引起类固醇肌病的机制。激活MAPKs信号途径或G蛋白耦联受体信号途径可能抑制糖皮质激素的信号转导。结论:激素疗法和运动疗法可以治疗类固醇肌病。光生物调节作用可以激活细胞MAPKs信号途径和G蛋白耦联受体信号途径,提示光生物调节作用是治疗类固醇肌病的一种潜在的疗法。     

Practicality, safety and accuracy of computed tomography coronary angiography in the evaluation of low TIMI-risk score chest pain patients: a pilot study

Objectives: The present pilot study aimed to assess the practicality, safety and accuracy of performing CT coronary angiography (CT‐CA) in the evaluation of acute chest pain of patients with low thrombolysis in myocardial infarction (TIMI) risk scores. Methods: The present prospective observational study was undertaken in a university teaching hospital between November 2004 and December 2005. Participants were a convenience sample of patients admitted to hospital for investigation of chest pain with TIMI risk scores <3. Consenting patients underwent CT‐CA within 48 h of presentation. Outcomes of interest were practicality (proportion of diagnostic quality scans obtained and preparation time for CT‐CA), rate of serious adverse events, and accuracy at the patient level using selective coronary angiography as the reference standard. Results: Thirty‐four patients were recruited. Diagnostic quality scans were obtained in 26/34 or 76% of patients (four failed CT‐CA and four non‐diagnostic scans). The median CT preparation time was 1.9 h (range 0.17–4.0). No serious adverse events were found. Fourteen of those 26 patients with diagnostic CT‐CA subsequently had selective coronary angiography, of which nine were positive. The sensitivity and specificity of CT‐CA in identifying patients with significant coronary artery disease were 9/9 (100%; 95% confidence interval 72–100%) and 4/5 (80%; 95% confidence interval 28–100%), respectively. Conclusions: The majority of acute chest pain patients with low TIMI risk scores were successfully scanned with a 16‐slice CT to produce CT‐CA studies with good diagnostic quality and accuracy. No major adverse events were found. The place of CT‐CA in diagnostic workup for chest pain remains to be defined.