A disulfide bridge network within the soluble periplasmic domain determines structure and function of the outer membrane protein RCSF

RcsF, a proposed auxiliary regulator of the regulation of capsule synthesis (rcs) phosphorelay system, is a key element for understanding the RcsC-D-A/B signaling cascade, which is responsible for the regulation of more than 100 genes and is involved in cell division, motility, biofilm formation, and virulence. The RcsC-D-A/B system is one of the most complex bacterial signal transduction pathways, consisting of several membrane-bound and soluble proteins. RcsF is a lipoprotein attached to the outer membrane and plays an important role in activating the RcsC-d-A/B pathway. The exact mechanism of activation of the rcs phosphorelay by RcsF, however, remains unknown. We have analyzed the sequence of RcsF and identified three structural elements: 1) an N-terminal membrane-anchored helix (residues 3-13), 2) a loop (residues 14-48), and 3) a C-terminal folded domain (residues 49-134). We have determined the structure of this C-terminal domain and started to investigate its interaction with potential partners. Important features of its structure are two disulfide bridges between Cys-74 and Cys-118 and between Cys-109 and Cys-124. To evaluate the importance of this RcsF disulfide bridge network in vivo, we have examined the ability of the full-length protein and of specific Cys mutants to initiate the rcs signaling cascade. The results indicate that the Cys-74/Cys-118 and the Cys-109/Cys-124 residues correlate pairwise with the activity of RcsF. Interaction studies showed a weak interaction with an RNA hairpin. However, no interaction could be detected with reagents that are believed to activate the rcs phosphorelay, such as lysozyme, glucose, or Zn(2+) ions.     

pspK acquisition contributes to the loss of capsule in pneumococci: molecular characterisation of non-encapsulated pneumococci

With the introduction of the pneumococcal conjugate vaccine (PCV), the number of cases of non-vaccine type pneumococci and non-encapsulated Streptococcus pneumoniae (NESp) infection have increased. In order to clarify how pspK-harbouring NESp might have emerged, we characterised NESp and analysed the correlation between transformation and non-encapsulation. A total of 26 NESp strains were used in this study. The genetic backgrounds were compared using multilocus sequence typing (MLST). The ΔpspK::ermB strain, in which pspK was replaced by ermB in NESp, was constructed by homologous recombination. The genomic DNA of the ΔpspK::ermB strain was transformed into two types of encapsulated S. pneumoniae via transformation. The fitness of the parent and non-encapsulated transformants was compared using the growth curve. All NESp had pspK instead of capsular coding regions and were classified into 14 types by MLST, which indicated that NESp had several genetic backgrounds. Transformation of ΔpspK::ermB genomic DNA resulted in 10⁻⁴‒10⁻⁵ non-encapsulated transformants. Non-encapsulated transformants could grow faster than the encapsulated parent strain. The acquisition of pspK region via transformation contributed to the loss of encapsulation with high frequency. The present results suggest that non-encapsulation through pspK acquisition could be a potential mechanism to evade PCV.     

单气囊小肠镜在诊断胶囊内镜检查阴性的可疑小肠疾病患者中的应用价值

目的：探讨单气囊小肠镜（single-balloonenteroscop,SBE）在胶囊内镜检查阴性的可疑小肠疾病患者中的应用价值。方法：选取在我院行胶囊内镜检查无异常发现,后行单气囊小肠镜检查的可疑小肠疾病患者24例,分析后者对胶囊内镜检查阴性可疑小肠疾病患者的阳性发现率和病因的分布特点。结果：24例行SBE检查者有22例（91．7％）获得成功,2例失败,10例被检出阳性病变,其中间质瘤5例,小肠息肉2例,过敏性紫癜1例,血管畸形2例,SBE对胶囊内镜检查阴性的患者小肠疾病的再检出率为41．7％。结论：胶囊内镜和SBE在小肠疾病的诊断上有着各自的优缺点,对于胶囊内镜检查阴性的可疑小肠疾病患者进一步行SBE检查有助于确诊。     

脑血康胶囊联合巴曲酶对急性脑梗死患者血清 MBP、NSE水平的影响

摘要 目的：研究脑血康胶囊联合巴曲酶对急性脑梗死患者血清髓鞘碱性蛋白(myebin bosic protein,MBP)、神经元特异性烯醇化酶(neuron-specific enolase,NSE)水平的影响。方法：选择2018年3月～2019年3月我院收治的161例急性脑梗死患者,将其随机分为两组。对照组静脉滴注巴曲酶,首次给予10 BU,隔日给予5 BU,每两天给药1次;观察组在巴曲酶的基础上联合口服脑血康胶囊,每天3 次,每次3粒。观察和比较两组治疗总有效率、治疗前后血清MBP、NSE、全血黏度(whole blood viscosity,WBV)、红细胞压积(hematocrit,HCT)、血浆黏度(plasma viscosity,PV)和纤维蛋白原(fibrinogen,FIB)水平及NHISS和BI评分的变化。结果：治疗后,观察组的有效率为91.25 %,明显高于对照组(64.2%,P<0.05);两组血清MBP、NSE、WBV、HCT、PV和FIB水平均较治疗前明显降低(P<0.05),且观察组的以上指标明显低于对照组(P<0.05);两组的BI评分明显升高(P<0.05),NHISS评分明显降低(P<0.05),观察组BI评分明显高于对照组,而NHISS评分明显低于对照组(P<0.05)。结论：脑血康胶囊联合巴曲酶对急性脑梗死有显著的疗效,能明显降低患者血清MBP、NSE水平,促进神经功能的恢复。     

扶正化瘀胶囊对心肌梗死大鼠心肌纤维化的影响

目的：急性心肌梗死是危害人类健康的重大疾病之一,心肌梗死后心肌纤维化是造成心脏结构破坏、心功能下降、心律失常发生、心衰甚至猝死的微观病理机制。防治心肌纤维化是当前医学研究的重点和热点。本研究主要探讨扶正化瘀胶囊对心肌梗死大鼠心肌纤维化的干预作用。方法：大鼠随机分为假手术组、模型组、扶正化瘀胶囊组和卡托普利组,采用结扎冠状动脉前降支的方法建立心肌梗死模型,假手术组只穿线,不结扎。于造模成功后第10天开始给予相应药物治疗2个月。治疗结束后,检测左心室梗死范围和心肌胶原含量。结果：与假手术组比较,模型组、扶正化瘀胶囊组和卡托普利组的非梗死区面积显著减小（P〈0.01）。与模型组比较,扶正化瘀胶囊组和卡托普利组的梗死区面积和梗死百分比显著减小（P〈0.05,P〈0.01）。在心肌胶原表达上,与假手术组比较,模型组和扶正化瘀胶囊组胶原含量显著增加（P〈0.01）。与模型组比较,卡托普利组和扶正化瘀胶囊组胶原含量显著降低（P〈0.05,P〈0.01）。结论：扶正化瘀胶囊能够改善心肌缺血,缩小心肌梗死范围,抑制心肌胶原表达,除能用于肝纤维化的治疗外,还能用于防治心肌梗死后的心肌纤维化。     

Effects of crowding on life history parameters of four green leafhoppers,Nephotettix spp. (Homoptera: Cicadellidae)

The effects of intraspecific crowding on the different life history parameters of the three tropical and subtropical green leafhoppers, Nephotettix virescensStål ,N. nigropictusDistant and N. malayanusIshihara etKawase , and one temperate species, N. cincticepsUhler , were studied under 25±1°C using the susceptible Japonica rice variety “Nipponbare”. Crowding during the immature stages of the four species prolonged the nymphal developmental period and resulted to smaller adults with reduced fecundity and shorter life span. Similarly, crowding during the adult stage also shortened the life span of both sexes of adults and decreased the fecundity of females of the four species. The effect of crowding during the adult stage was more adverse than the effect of crowding during the immature stages. N. cincticeps seemed more sensitive to crowding even at lower densities whereas the three tropical species were sensitive mostly at higher densities.     

细菌“特殊结构”之浅见

细菌的结构是病原生物学课程教学中最为基础的教学内容.随着科学技术和研究方法的发展,人们对细菌结构的认识也愈加深入.对国内教材普遍采用的细菌“特殊结构”概念提出不同的观点,试与同行切磋探讨.     

顺天胶囊药理学实验研究Ⅱ.顺天胶囊对幼鼠性功能及抗疲劳作用的影响

本文探讨了顺天胶囊对幼鼠性机能的影响和抗疲劳等作用。实验结果表明,本品对雌性幼鼠性机能无明显影响作用,但能明显提高雄性幼鼠前列腺一精囊重量和睾丸酮水平,明显延长小鼠游泳时间。提示本品具有提高雄性动物性机能及明显抗疲劳作用。     

复方银杏胶囊镇痛作用及其机制的实验研究

目的:研究复方银杏胶囊的镇痛作用及其机制.方法:大鼠电刺激法测定痛阈;用试剂盒比色法测定脑组织中谷氨酸的含量;原子吸收光谱法测定脑组织中钙离子(Ca2 )浓度;免疫组织化学ABC法观察脑组织中N-甲基-D-天门冬氨酸Ⅰ型受体(NMDAR1)的分布.结果:复方银杏胶囊350 mg/kg可显著提高大鼠电刺激嘶叫阈(P＜0.05),700 mg/kg显著减少小鼠脑组织中谷氨酸的释放以及脑内钙离子浓度(P＜0.05);复方银杏胶囊700 mg/kg、350 mg/kg可明显减少疼痛模型小鼠大脑皮层NMDAR1阳性细胞数(P＜0.01,P＜0.05).结论:复方银杏胶囊具有良好的镇痛效应,其镇痛作用可能与拮抗NMDA受体从而抑制脑组织中谷氨酸的释放及钙离子内流有关.     

Heterotylenchus antumnalis. Hemocytic reactions and capsule formation in the host, Musca domestica

Failure of the nematode H. autumnalis to develop in M. domestica is attributed to the defense reaction of host larvae to the infective, gamogenetic stage of the parasite. The defense reaction involves melanization and encapsulation of the parasite, and is manifested as changes in the hemocyte picture of the host.