肺炎克雷伯菌、类肺炎克雷伯菌和变栖克雷伯菌的研究进展

肺炎克雷伯菌临床分离株是一种有荚膜的革兰阴性粗短杆菌,是临床上重要的机会致病菌。肺炎克雷伯菌临床分离株基因间存在差异,依据系统发育树可分为肺炎克雷伯菌(Klebsiella pneumoniae, KpⅠ)、类肺炎克雷伯菌(Klebsiella quasipneumoniae, KpⅡ)和变栖克雷伯菌(Klebsiella variicola, KpⅢ),三者生态分布、基因型、耐药性、毒力特征以及致病性存在显著差异,为感染性疾病精准治疗带来新的挑战。本文对KpⅠ、KpⅡ、KpⅢ的鉴定、流行特点及致病特点的最新研究进展进行综述。     

匹莫齐特对金黄色葡萄球菌的体外和体内抗菌研究

目的 探讨抗精神病类药物匹莫齐特对金黄色葡萄球菌的体外和体内抗菌活性。方法 采用微量肉汤稀释法检测匹莫齐特的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)。通过96孔细胞培养板构建生物膜,利用比浊法检测匹莫齐特的抗生物膜活性,进一步通过激光共聚焦显微镜和SYTO9/PI染色观察匹莫齐特对生物膜的作用。采用棋盘稀释法检测匹莫齐特与抗菌药物联合抗菌效果,CCK-8试剂盒检测匹莫齐特的细胞毒性。构建皮肤脓肿模型,检测匹莫齐特的体内抗菌活性及毒性。结果 匹莫齐特对金黄色葡萄球菌具有明显的剂量依赖抑菌活性,其MIC为8～16μg/mL,能显著抑制金黄色葡萄球菌生物膜的形成并分散已形成的生物膜。匹莫齐特与多西环素联合,体外具有协同抗菌效果,其协同抑菌指数为0.5;体内能显著降低小鼠脓肿组织中的细菌载量,使活菌量从(8.25±0.13)对数值CFU/脓肿减少到(3.31±0.81)对数值CFU/脓肿(q=3.74,P<0.05);匹莫齐特的细胞毒性极低,对细胞的半数抑制浓度>64μg/mL。结论 匹莫齐特毒性低且具有明显的体外和体内抗菌活性,有望成为一种精神病患者合并局部金黄色葡萄球菌相...     

Nucleic acid vaccination of Brucella abortus ribosomal L7/L12 gene elicits immune response

Nucleic acid vaccines provide an exciting approach for antigen presentation to the immune system. As a test of this new methodology, the immune response to the in vivo-expressed Brucella abortus ribosomal L7/12 gene in the muscle cells of mice was examined. To accomplish this goal the eukaryotic expression systems pcDNA3 and p6 were used. Single intramuscular injection of the L7/L12 gene driven by the human cytomegalovirus (CMV) promoter (pcDNA3) or bovine MHC I promoter (p6) resulted in intracellular expression of the B. abortus L7/L12 immunodominant protein encoded by this gene. This application facilitated directed antigen presentation to the immune system and established specific antibody and T-cell responses compared with vector only (pcDNA₃) negative controls and B. abortus S19 injected positive controls. Although pcDNA₃-encoded L7/L12 gene-inoculated mice possessed significant protection, p6-L7/L12 did not engender significant protection against B. abortus S2308 infection compared to positive control mice. These data suggest a promising antigen-specific response, and L7/L12 nucleic acid vaccination may be an initial step in the development of genetically engineered candidate vaccines against brucellosis. This study for the first time focuses on DNA immunization of a gene from B. abortus.     

Laboratory Evaluation of the Toxicity of Perfluorooctane Sulfonate (PFOS) on Selenastrum capricornutum , Chlorella vulgaris , Lemna gibba , Daphnia magna , and Daphnia pulicaria

Perfluorooctane sulfonate (PFOS) is an anthropogenic compound found in trace amounts in many environmental compartments far from areas of production. This, along with the highly persistent nature of PFOS, presents a concern for possible effects in aquatic ecosystems. The objective of this study was to determine the toxicity of PFOS in representative freshwater organisms. Toxicity testing using standard laboratory protocols was performed on the green algae Selenastrum capricornutum and Chlorella vulgaris, the floating macrophyte Lemna gibba, and the invertebrates Daphnia magna and Daphnia pulicaria. No observable effect concentration (NOEC) values were generated from the most sensitive endpoints for all organisms. Autotroph inhibition of growth NOEC values were 5.3, 8.2, and 6.6 mg/L for S. capricornutum, C. vulgaris, and L. gibba, respectively. The 48-h immobility NOEC values for D. magna and D. pulicaria were 0.8 and 13.6 mg/L, respectively. In comparison to immobility, the 21-day lethality NOEC for D. magna was 5.3 mg/L. Based on effect (immobility) values, the most sensitive of all test organisms was D. magna. The most sensitive organism based on 50% inhibition of growth (IC₅₀) was L. gibba, with an IC₅₀ value of 31.1 mg/L determined from wet weight. This is 4.3 times less than the LC₅₀ for D. pulicaria, which was 134 mg/L. Significant adverse effects (p ≤ 0.05) were observed for all organisms in concentrations >134 mg/L. The results indicate that under laboratory conditions PFOS is acutely toxic to freshwater organisms at concentrations at or near 100 mg/L. Based on known environmental concentrations of PFOS, which occur in the low ng/L to low μg/L range, there is no apparent risk to freshwater systems. However, further work is required to investigate long-term effects in these and other freshwater organisms. Received: 2 May 2002/Accepted: 29 July 2002     

空肠弯曲菌Cj1136、Cj1138、Cj1139基因对比研究

目的 了解吉兰-巴雷综合征(GBS)相关空肠弯曲菌(C.jejuni)的Cj1136、Cj1138、Cj1139基因序列特征,并同GenBank中的非GBS相关C.jejuni菌株对应序列进行比较,找出可能使C.jejuni菌株具有致GBS能力的碱基突变.方法 选取分离自GBS患者粪便并经动物模型证实为致GBS的AMAN型C.jejuni 3株进行培养并提取基因组DNA测序.将基因测序结果与NCTC11168菌株进行对照比较,寻找此3株C.jejuni的Cj1136、Cj1138、Cj139基因突变位点,并计算此3株致GBS C.jejuni的Cj1136、Cj1138、Cj1139基因序列间的遗传距离.结果 3株致GBSC.jejuni菌株的Cj1136基因由1173个碱基构成;Cj1138基因由1170个碱基构成;Cj1139基因由912个碱基构成,与NCTC11168的Cj1136、Cj1138、Cj1139基因序列相比,此3株致GBS C.jejuni中只有Cj1138存在2个相同的碱基突变.遗传距离计算,3株致GBS C.jejuni的Cj1136、Cj1138、Cj1139基因之间最大遗传距离为2.1%.结论 与NCTC11168相比GBS相关C.jejuni中Cj1138基因序列存在相同碱基突变,这些碱基突变可能与C.jejuni致GBS能力的改变相关.该3株致GBSC.jejuni的Cj1136、Cj1138、Cj1139基因遗传距离较小,反映河北地区致GBS的C.jejuni在进化上存在聚类现象,具有一定的区域特征.     

建设世界一流科技期刊的策略——基于Nature、Science、The Lancet和Cell的分析

【目的】 探索建设世界一流科技期刊的策略,以助力中国科技期刊冲刺世界一流水平。【方法】 通过研读相关政策和研究文献,结合对Nature、Science、The Lancet、Cell等不同类型的世界一流科技期刊的分析,解析世界一流科技期刊的概念及内涵,探讨建设世界一流科技期刊的充分条件和必要条件,提出建设世界一流科技期刊的建议。【结果】 卓越的办刊理念、全方位的国际化水平、世界一流的人才队伍、先进的经营管理水平以及汇聚一流前沿成果、卓著的科学声望是建设世界一流科技期刊的必要条件。“高、精、尖”和“稳、准、狠”的办刊策略,是建设世界一流科技期刊的充分条件。建设世界一流科技期刊要理性且准确地认知其内涵,始终坚持卓越的办刊理念、国际化战略、人才战略、质量战略和集群化战略。【结论】 中国科技期刊既要扎根祖国大地,又要学习世界一流期刊的成功经验,从办刊的硬实力和软实力方面吸收借鉴,才能探索出具有中国特色的世界一流科技期刊建设路径。     

Evolutionary origin of the Jiv90 gene of Pestivirus

Phylogenetic analyses were used to test the hypothesis that the Jiv90 insert in the genomes of Pestivirus species originated by horizontal transfer from their hosts (mammals in the order Artiodactyla). The results supported this hypothesis because the Jiv90 insert clustered with the corresponding domains of mammalian Jiv proteins and closer to artiodactyl than to rodent or primate genes. A phylogeny of Pestivirus genotypes showed that the Jiv90 insert occurred only in one clade (Pestivirus Type 1), although numerous members of this clade lacked the insert. This pattern is probably most easily explained on the hypothesis that the insert occurred in the common ancestor of the Type 1 clade and that it has been subsequently lost independently by several members of the clade.     

中国土拉弗朗西斯菌holarctica亚种的遗传多样性

目的 研究国内外土拉弗朗西斯菌的遗传进化关系。方法 选择17个单核苷酸多态性、4个插入/缺失和12个可变数目串联重复,采用单核苷酸多态性和插入/缺失、多位点可变数目串联重复分析方法单独和组合起来对39株土拉菌(10株中国土拉菌和29株已公布测序的土拉菌)进行系统进化分析。结果 组合分析显示,3株中国土拉菌和日本的FSC022被分配到B5;剩余3株中国土拉菌和瑞典的FSC200被分配到B1;3株和美国的OSU18被分配到B2;1株和法国的FTNF002-00、德国的F92与美国的OR96246一起被分配到B4。10株中国土拉菌分为4种亚型,研究表明中国土拉菌具有广泛的遗传多样性。结论 本研究针对土拉菌B型建立了一套简易高效的分型方法,并以此为基础得出土拉菌B型的起源可能是亚洲地区。     

The composition of Hirsutella sinensis, anamorph of Cordyceps sinensis

The compositions of natural fruiting bodies of Cordyceps sinensis (NFCS), mycelia from submerged culture (MSMC) and shake culture (MSKC) of RCEF0273, a strain of Hirsutella sinensis, anamorph of C. sinensis, were compared to evaluate the potentiality of MSMC. The contents of crude fat, crude protein, total and essential amino acids were in the following descending order: MSKC>MSMC>NFCS, respectively. Unsaturated fatty acids of MSMC accounted for 65.9% of total fatty acids, obviously lower than those of NFCS (86.9%) and MSKC (76.5%). Both As and Hg were lower than 0.20 μg/g in all samples tested. The contents of Ca, Se and Cu were higher in MSMC than in NFCS, while the contents of Fe, Zn and Sn, were lower in MSMC than in NFCS. Vitamin B₆ was not detected in MSMC but in NFCS, while vitamin B₁ was not found in NFCS but in freeze-dried MSMC. Niacin content of NFCS was 1.6 times more than that of MSMC. The total content of four nucleosides (adenosine, guanosine, uridnine and inosine) in MSMC (6.20 mg/g) was significantly higher than those of NFCS (1.80 mg/g) and MSKC (1.60 mg/g). The above results suggest that MSMC can probably be used as a substitute for NFCS.     

The detection of Yersinia enterocolitica in surface water by quantitative PCR amplification of the ail and yadA genes

Yersinia enterocolitica has been detected in surface water, and drinking untreated water is a risk factor for infection. PCR-based methods have been used to detect Y. enterocolitica in various sample types, but quantitative studies have not been conducted in water. In this study, quantitative PCR (qPCR)-based methods targeting the Yersinia virulence genes ail and yadA were used to survey the Grand River watershed in southern Ontario, Canada. Initial testing of reference strains showed that ail and yadA PCR assays were specific for pathogenic biotypes of Y. enterocolitica; however the genes were also detected in one clinical Yersinia intermedia isolate. A survey of surface water from the Grand River watershed showed that both genes were detected at five sampling locations, with the ail and yadA genes detected in 38 and 21% of samples, respectively. Both genes were detected more frequently at colder water temperatures. A screening of Yersinia strains isolated from the watershed showed that the ail gene was detected in three Y. enterocolitica 1A/O:5 isolates. Results of this study show that Yersinia virulence genes were commonly detected in a watershed used as a source of drinking water, and that the occurrence of these genes was seasonal.     

日月潭按蚊对间日疟原虫易感性的实验研究

本文报告日月潭按蚊对间日疟原虫易感性的实验观察结果。以8例间日疟患者血离体感染8批日月潭按蚊,其中4批腺感染率达100%,阳性腺指数平均为3.73。原虫在蚊体内发育良好,在感染后第8天卵囊分化,第9天涎腺阳性,其发育速度和分化卵囊体积均和在微小按蚊体内者一致。说明该蚊对间日疟原虫具高度易感性。其自然感染率低主要是偏嗜畜血的习性所致。显然,该蚊在一定条件下可起重要传疟作用,不应忽视。     

Fluorescence analysis detects gp60 subtype diversity in Cryptosporidium infections

Ninety percent of human cryptosporidiosis infections are attributed to two species; the anthroponotic Cryptosporidium hominis and the zoonotic Cryptosporidium parvum. Sequence analysis of the hypervariable gp60 gene, which is used to classify Cryptosporidium to the subtype level, has highlighted extensive intra-species diversity within both C. hominis and C. parvum. The gp60 has also facilitated contamination source tracking and increased understanding of the epidemiology of cryptosporidiosis. Two surface glycoproteins, the gp40 and gp15 are encoded in the gp60 gene; both are exposed to the hosts’ immune system and play a pivotal role in the disease initiation process. The extent of genetic diversity observed within the gp60 would support the hypotheses of significant selection pressure placed on the gp40 and gp15. This study used a dual fluorescent terminal-restriction fragment length polymorphism (T-RFLP) analysis to investigate the genetic diversity of Cryptosporidium subtype populations in a single host infection. Terminal-RFLP showed subtype variation within one human Cryptosporidium sample and mouse samples from seven consecutive passages with C. parvum. Furthermore, this was the first study to show that differences in the ratio of subtype populations occur between infections. T-RFLP has provided a novel platform to study infection populations and to begin to investigate the impact of the hosts’ immune system on the gp60 gene.     

Changes in aromatic characteristics of Loureiro and Alvarinho wines during maturation

Changes in volatiles during maturation in bottles of monovarietal Vinhos Verdes wines from Loureiro and Alvarinho grape varieties, were followed by chemical and sensory analyses. Young wines and wines matured for 8 and 20 months were studied. The volatiles were determined by gas chromatography–mass spectrometry (GC-MS) after extraction on XAD-2 resin. Straight chain fatty acid ethyl esters and acetates of fusel alcohols decreased quicker for Loureiro wine, while the increase in ethyl esters of branched fatty acids was similar for both varieties. Linalool, Ho-trienol, α-terpineol and β-damascenone could be used to differentiate between each variety. However, linalool decreased to negligible values after 20 months of maturation. β-Damascenone decreased but remained high enough to be useful for differentiating each variety. Sensory analysis indicated a decrease of tropical fruit and tree fruit characters with conservation time for Alvarinho wine, and the opposite for Loureiro; moreover, citrus fruit character decreased in both varieties.