2011年、2013年和2016年医院内获得性血流感染常见病原菌分布及其耐药性分析

动态监测2011年、2013年和2016年我国不同地区医院内获得性血流感染病原菌分布及耐药进展趋势。从全国10个城市回顾性收集血流感染病原菌非重复性株,采用琼脂稀释法或微量肉汤稀释法进行药物敏感性试验,采用Whonet 5.6软件对药敏试验结果进行分析。收集的2 248株血流感染病原菌中革兰阴性杆菌为1 657株 (占73.7%),革兰阳性球菌为591株 (占26.3%)。分离率排名前五的病原菌依次为大肠埃希菌 (32.6%,733株/2 248株)、肺炎克雷伯菌 (14.5%,327株/2 248株)、金黄色葡萄球菌 (10.0%,225株/2 248株)、鲍曼不动杆菌 (8.7%,196株/ 2 248株) 和铜绿假单胞菌 (6.2%,140株/2 248株)。血流感染分离的革兰阴性杆菌对抗菌药物体外敏感率较高的抗菌药物依次为粘菌素 (96.5%,1 525株/1 581株,不包括天然耐药菌株)、替加环素 (95.6%,1 375株/1 438株,不包括天然耐药菌株)、头孢他啶/克拉维酸 (89.2%,1 112株/1 246株)、阿米卡星 (86.4%,1 382株/1 599株) 和美罗培南 (85.7%,1 376株/1 605株);革兰阳性球菌对抗菌药物体外敏感率较高的抗菌药物依次为替加环素、替考拉宁和达托霉素 (敏感率均为100.0%)、万古霉素和利奈唑胺 (敏感率均为99.7%)。2011年、2013年和2016年产超广谱β-内酰胺酶肠杆菌科细菌分离率分别为50.6% (206株/407株)、49.8% (136株/273株) 和38.9% (167株/429株);碳青霉烯不敏感肠杆菌科细菌分离率分别为2.2% (9株/408株)、4.0% (16株/402株) 和3.9% (17株/ 439株);多重耐药鲍曼不动杆菌分离率分别为76.4% (55株/72株)、82.7% (43株/52株) 和87.5% (63株/72株),多重耐药铜绿假单胞菌分离率分别为9.8% (5株/51株)、20.0% (7株/35株) 和13.0% (7株/54株);甲氧西林耐药金黄色葡萄球菌的分离率分别为51.9% (41株/79株)、29.7% (19株/64株) 和31.7% (26株/82株)。屎肠球菌和粪肠球菌中高水平庆大霉素耐药株分离率分别为43.2% (48株/111株) 和40.9% (27株/66株)。碳青霉烯不敏感肠杆菌科细菌中肺炎克雷伯菌居首位,占57.1% (24株/42株) 。肠杆菌科细菌中分离出30株替加环素不敏感株,其中肺炎克雷伯菌占76.7% (23株/30株);分离出粘菌素耐药肠杆菌科细菌39株,其中大肠埃希菌、阴沟肠杆菌和肺炎克雷伯菌分别占43.6% (17株/39株)、35.9% (14株/39株) 和15.4% (6株/39株)。医院获得性血流感染病原菌主要为革兰阴性杆菌 (以大肠埃希菌和肺炎克雷伯菌为主),其对替加环素、粘菌素和碳青霉烯类药物的敏感率较高;革兰阳性球菌中分离率最高的为金黄色葡萄球菌,其次为屎肠球菌,这两种细菌对替加环素、达托霉素、利奈唑胺、万古霉素和替考拉宁的敏感率较高。粘菌素耐药肠杆菌科细菌、替加环素不敏感肠杆菌科细菌、利奈唑胺或万古霉素不敏感革兰阳性球菌的分离,警示临床高度关注,仍需动态监测耐药进展趋势。     

嗜热酯酶APE1547催化活性的定向进化研究

对来源于嗜热古菌Aeropyrum pernix的酯酶(APE1547)催化活性进行定向进化研究。利用APE1547特殊的稳定性,建立了准确的高通量高温酯酶筛选方法。对第一代随机突变库筛选获得了催化活性较野生型提高1.5倍的突变体M010,序列分析表明其氨基酸突变为R526S。从第二代突变库中筛选出的总活力提高5.8倍突变体M020,突变位点为R526S/E88G/A200T/I519L,其比活力与M010一致,但表达量比野生型提高约4倍。对M020酶学性质表征发现,其最适pH为8.5,比野生型向碱性偏移0.5;活性中心残基酸性基团的解离常数(pK1)由野生型的7.0提高至7.5。晶体结构分析表明,突变位点R526距离活性中心较近,将其突变为Ser降低了活性中心的极性,抑制了催化残基His的解离,使酸性基团的解离常数升高。     

兰属Cymbidium植物ISSR遗传多样性分析

将简单重复序列区间扩增多态标记(inter-simple sequence repeats, ISSR)技术应用于16种兰属的遗传多样性分析, 15个引物共扩增出836条带, 其中有227条多态带, 多态百分比为27.2%。UPGMA聚类结果显示: 春兰与春剑的亲缘关系最近, 而兔耳兰与其他15种兰属植物的距离最远。ISSR聚类结果与传统分类结果基本相似, 表明该技术能在分子水平上对传统兰属分类进行必要补充。     

Testing the responses of four wheat crop models to heat stress at anthesis and grain filling

Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT‐CERES‐Wheat, DSSAT‐Nwheat, APSIM‐Wheat, and WheatGrow) were evaluated with 4 years of environment‐controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 °C), grain filling duration was reduced by 0.30–0.60%, total aboveground biomass was reduced by 0.37–0.43%, and grain yield was reduced by 1.0–1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies.     

内耳淋巴液的来源、性质和成分

内耳淋巴液中外淋巴液的来源有2种说法:①来源于脑脊液;②来自毛细血管的血液超滤液。内淋巴可能是以分泌方式产生的,二者性质与成分存在一定的差异     

Characterization of humoral responses in mice immunized with plasmid DNAs encoding SARS-CoV spike gene fragments

The immunological characteristics of SARS-CoV spike protein were investigated by administering mice with plasmids encoding various S gene fragments. We showed that the secreting forms of S1, S2 subunits and the N-terminus of S1 subunit (residues 18-495) were capable of eliciting SARS-CoV specific antibodies and the region immediate to N-terminus of matured S1 protein contained an important immunogenic determinant for elicitation of SARS-CoV specific antibodies. In addition, mice immunized with plasmids encoding S1 fragment developed a Th1-mediated antibody isotype switching. Another interesting finding was that mouse antibodies elicited separately by plasmids encoding S1 and S2 subunits cooperatively neutralized SARS-CoV but neither the S1 nor S2 specific antibodies did, suggesting the possible role of both S1 and S2 subunits in host cell docking and entry. These results provide insights into understanding the immunological characteristics of spike protein and the development of subunit vaccines against SARS-CoV.     

Recombinant Galectins of <Emphasis Type="Italic">Haemonchus contortus</Emphasis> Parasite Induces Apoptosis in the Peripheral Blood Lymphocytes of Goat

The effect of Haemonchus contortus galectin peptides rHco-gal-m/f to induce apoptosis in the peripheral blood lymphocytes (PBLCs) of goats was investigated. Analysis of apoptosis was carried out with agarose gel electrophoresis, flow cytometry and transmission electron microscopy. The results indicated that there were visible apoptosis bodies and typical DNA ladders by genomic DNA fragmentation. The quantitative analysis of apoptosis by flow cytometry indicated that rHco-gal-m/f peptides induced apoptosis was time and dose dependent. Ultrastructural studies of the PBLCs revealed that a large number of apoptotic cells were present in galectin-treated cells, which had the typical morphologic changes of apoptosis such as reduction of the cytoplasmic volume, loss of cell surface microvilli, chromatin condensation and fragmentation of the apoptotic cells into small apoptotic bodies.