Diagnostic and Prognostic Value of Left Atrial Function in Identification of Cardioembolism and Prediction of Outcomes in Patients with Cryptogenic Stroke

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军医大学本科生鼻腔定植金黄色葡萄球菌和其他可培养菌群的筛查

目的了解鼻腔金黄色葡萄球菌(SA)和其他可培养共生菌的定植情况,为鼻腔定植条件致病菌特别是SA的感染预防及其医院感染控制措施的制定提供参考依据。方法采集在某院临床医学课程学习的健康军医大学本科生鼻前庭标本,以微生物自动化系统接种于各类细菌培养基进行细菌培养和菌落观察,对分离菌株采用质谱鉴定,对SA进行抗菌药物敏感性试验。结果共采集鼻前庭标本161份,检出鼻腔定植菌549株,其中革兰阳性菌493株,革兰阴性菌56株,居前三位的细菌为拥挤棒状杆菌(151株)、表皮葡萄球菌(150株)、假白喉棒状杆菌(54株)。共有72种不同的带菌模式,以同时检出金黄色葡萄球菌、表皮葡萄球菌和拥挤棒状杆菌带菌模式的学员最多,达21名(13.04%)。鼻腔SA定植率为25.46%(41/161),耐甲氧西林金黄色葡萄球菌(MRSA)定植率为4.35%(7/161),SA菌株对青霉素、红霉素和克林霉素耐药率为39.02%～78.05%。结论军医大学本科生鼻腔定植菌群以正常菌群为主,需注意定植的SA和其他条件致病菌导致自身感染和引发医院感染的可能性。     

海南地区疑似肺结核患者非结核分枝杆菌感染特征

目的了解海南地区疑似肺结核患者非结核分枝杆菌(NTM)的菌种分布、耐药性及临床感染特征。方法收集2015年1月—2018年8月海南省某院疑似肺结核患者痰、肺泡灌洗液等呼吸道标本进行培养、菌种鉴定,对NTM感染情况、药敏结果,以及NTM肺部感染患者临床资料进行分析。结果共有833份疑似肺结核患者阳性呼吸道标本,其中126份初步鉴定为NTM,经菌种鉴定,检出结核分枝杆菌3株,检出非分枝杆菌属细菌3株,检出的4株NTM无法鉴定至种,最终116份标本中检出NTM118株。109例为单一NTM感染,7例为混合感染。有8种NTM菌种类型,主要以龟/脓肿分枝杆菌(41.5%)和胞内分枝杆菌(37.3%)为主。8种NTM菌种对8种一、二线抗结核药物呈不同程度的耐药,总耐药率最高的为异烟肼(96.6%),对8种抗结核药物全部耐药的比率高达32.2%。NTM肺部感染患者中男性少于女性,主要好发于中老年人,患者主要以海南沿海地区为主。NTM肺部感染患者主要临床表现为咳嗽咳痰、胸闷气促、血痰或咯血、食欲减退及体重下降,基础疾病既往有结核病史、支气管扩张、肺部感染及咯血,影像学表现为继发型肺结核、肺部空洞、胸膜肥厚、支气管扩张伴有肺气肿及肺部感染。结论海南地区NTM肺部感染主要是以龟/脓肿分枝杆菌和胞内分枝杆菌为主,NTM对常用的抗结核药物均具有较高的耐药性,NTM肺部感染与肺结核应依据病原学检查进行鉴别。     

Increased detection of G3P[9] and G6P[9] rotavirus strains in hospitalized children with acute diarrhea in Bulgaria

Rotavirus severe disease in children is now vaccine-preventable and the roll-out of vaccination programs globally is expected to make a significant impact in the reduction of morbidity and mortality in children <5 years of age. Rotavirus is also a pathogen of other mammals and birds, and its segmented RNA genome can lead to the emergence of new or unusual strains in human population via interspecies transmission and reassortment events. Despite the efficacy and impact of rotavirus vaccine in preventing severe diarrhea, the correlates of protection remain largely unknown. Therefore, rotavirus strain surveillance before, during and after the introduction of immunization programs remains a crucial for monitoring rotavirus vaccine efficacy and impact. In this context, molecular characterization of 1323 Bulgarian rotavirus strains collected between June 2010 and May 2013 was performed. A total of 17 strains of interest were analyzed by partial sequence analysis. Twelve strains were characterized as G3P[9] and G6P[9] of potential animal origin. Phylogenetic analysis and comparisons with the same specificity strains detected sporadically between 2006 and 2010 revealed the constant circulation of these unusual human strains in Bulgaria, although in low prevalence, and their increased potential for person-to-person spread.     

A novel transducible chimeric phage from Escherichia coli O157:H7 Sakai strain encoding Stx1 production

Shiga toxin-producing Escherichia coli (STEC), and especially enterohaemorrhagic E. coli (EHEC) are important, highly virulent zoonotic and food-borne pathogens. The genes encoding their key virulence factors, the Shiga toxins, are distributed by converting bacteriophages, the Stx phages. In this study we isolated a new type of inducible Stx phage carrying the stx1 gene cluster from the prototypic EHEC O157:H7 Sakai strain. The phage showed Podoviridae morphology, and was capable of converting the E. coli K-12 MG1655 strain to Shiga toxin-producing phenotype. The majority of the phage genes originate from the stx2-encoding Sakai prophage Sp5, with major rearrangements in its genome. Beside certain minor recombinations, the genomic region originally containing the stx2 genes in Sp5 was replaced by a region containing six open reading frames from prophage Sp15 including stx1 genes. The rearranged genome, together with the carriage of stx1 genes, the morphology and the capability of lysogenic conversion represent a new type of recombinant Stx1 converting phage from the Sakai strain.     

动态轴向压应变促进丝素蛋白支架内MC3T3-E1细胞成骨分化

目的 观察动态轴向压应变对三维丝素蛋白支架内成骨细胞成骨相关基因表达的影响。方法 应用动态力学加载仪对实验组小鼠胚胎成骨细胞MC3T3-E1加载动态轴向压应变（5%应变幅度,1 Hz,30 min/d,共21 d）,对照组细胞常规静置培养,不施加力学刺激。应用定量PCR检测细胞成骨基因碱性磷酸酶（ALP）、I型胶原（COLⅠ）、骨特异性转录因子（Runx2）、成骨相关转录因子（Osx）、骨钙蛋白（OCN） mRNA表达量。结果 成骨细胞在周期性轴向压应力刺激下,Runx2、Osx及COLⅠ表达分别增加280%、68.9%和79.6%,ALP及OCN表达也分别增加10.7%和26.9%。实验组成骨相关基因mRNA表达与对照组比较,差异具有统计学意义（P<0.05）。结论 成骨细胞复合丝素蛋白生物支架材料在周期性轴向压应力刺激下,成骨基因COLⅠ、Runx2、Osx及OCN表达明显上调,可能是生理状态下压应力刺激促进骨折愈合的重要机制之一。研究结果对于以力学信号为基础的细胞疗法修复骨缺损等疾病具有重要临床价值。     

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry–high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress–strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P < 0.01), whereas no differences in these parameters were found distal to the obstruction site (P > 0.25). The circumferential stress–strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and biomechanical remodeling likely influence the function of the intestine affected by partial obstructed intestine.