长白山地区红松树干呼吸的研究

采用土壤呼吸气室于2003年5～10月测定了长白山阔叶红松林主要树种红松不同径阶不同方位的树干呼吸,同时监测了树干温度和林内温度.结果表明,树干呼吸速率具有明显的季节变化趋势,呈单峰曲线,8月出现最大值,2月呼吸速率最低.树干呼吸速率与树干温度具有显著幂指数关系,同时表现出大径阶树干呼吸速率与温度因子间曲线拟合效果好于小径阶红松.不同径阶树干呼吸速率均呈南面高于北面,并随树干径阶的减小南北面呼吸速率差异降低.不同径阶红松树干平均维持呼吸占总树干呼吸63.63%,红松树干径阶越大维持呼吸所占比例越大.依树干径阶大小顺序分别为66.76%、73.29%和50.84%.不同径阶红松树干呼吸Q₁₀值在2.56～3.32之间,利用呼吸Q₁₀值分别获得不同径阶树干R_t和R_m的季节变化趋势.因此,当估算生态系统呼吸时应考虑树干不同部位和不同径阶之间的差异.     

Spatial heterogeneity of ecosystem health and its sensitivity to pressure in the waters of nearshore archipelago

The ecosystem-based management of nearshore waters requires synthesis of spatial data on the distribution of ecological conditions and intensity of anthropogenic perturbations, and the overlay of their effects on the ecosystem health. An assessment framework for ecosystem health incorporating 4 components namely vigor, organization, resilience and maintenance was proposed in this paper, based on which an analytical approach was developed to quantify the integrated effects of island mass and anthropogenic pressures on the waters of nearshore archipelago. The southern waters of Miaodao Archipelago, which are located in the intersection of the Bohai Sea and the Yellow Sea, China, were taken as a typical example to acquire the spatial heterogeneity of the ecosystem health and its sensitivity to multiple anthropogenic pressures. Results indicated that there was a relatively significant performance of the spatial heterogeneity for the ecosystem health. It presented that the interisland waters were poorer health than the external waters, and the waters adjacent to the continent functioned less well than those in a relatively open area. This phenomenon was primarily determined by the performance of vigor as well as resilience of ecosystem. For the 4 components of ecosystem health, there were an obvious spatial heterogeneity of vigor as well as the resilience, a seasonal succession of organization, and a spatiotemporal uniformity of maintenance. Moreover, the ecosystem health was more sensitive to the stressors of inland activities and coastline exploitation especially in the waters of Miaodao Bay and Changdao Port. The analytical process and resulting maps provide flexible tools for regional efforts to implement ecosystem-based management in the waters of archipelago and further nearshore waters so as to promote their sustainable development.     

Biochemical characterization of maintenance DNA methyltransferase DNMT-1 from silkworm,Bombyx mori

DNA methylation is an important epigenetic mechanism involved in gene expression of vertebrates and invertebrates. In general, DNA methylation profile is established by de novo DNA methyltransferases (DNMT-3A, -3B) and maintainance DNA methyltransferase (DNMT-1). DNMT-1 has a strong substrate preference for hemimethylated DNA over the unmethylated one. Because the silkworm genome lacks an apparent homologue of de novo DNMT, it is still unclear that how silkworm chromosome establishes and maintains its DNA methylation profile. As the first step to unravel this enigma, we purified recombinant BmDNMT-1 using baculovirus expression system and characterized its DNA-binding and DNA methylation activity. We found that the BmDNMT-1 preferentially methylates hemimethylated DNA despite binding to both unmethylated and hemimethylated DNA. Interestingly, BmDNMT-1 formed a complex with DNA in the presence or absence of methyl group donor, S-Adenosylmethionine (AdoMet) and the AdoMet-dependent complex formation was facilitated by Zn²⁺ and Mn²⁺. Our results provide clear evidence that BmDNMT-1 retained the function as maintenance DNMT but its sensitivity to metal ions is different from mammalian DNMT-1.     

医院计算机化医疗设备的维护管理

现代医疗设备大都采用了计算机化设计,分析了目前医院拥有的计算机现状、医疗设备的分类和管理。最后,提出了维护管理措施。     

维持性血液透析患者慢性肾脏病矿物质和骨异常患病情况调查及血管钙化的危险因素分析

目的:调查维持性血液透析(MHD)患者慢性肾脏病矿物质和骨异常(CKD-MBD)患病情况,并分析血管钙化的危险因素。方法:选取2017年2月～2018年12月我院收治的MHD患者229例记为研究对象。统计并记录所有患者CKD-MBD患病情况,并通过Kauppila评分对所有患者的血管钙化情况予以评定,将患者按照Kauppila评分结果分为钙化组与非钙化组。比较两组患者基本资料以及血生化指标水平,并采用多因素Logistic回归分析MHD患者血管钙化的影响因素。结果:229例MHD患者中CKD-MBD患病率按照从高到低的顺序分别为高甲状旁腺激素(PTH)、高磷血症、低钙血症、低PTH、高钙血症、低磷血症,占比分别为45.85%、42.36%、30.57%、20.09%、19.65%、10.04%。229例MHD患者血管钙化发生率为68.56%。钙化组年龄、透析时间、血磷、颈动脉内膜中层厚度(IMT)、超敏C反应蛋白(hs-CRP)水平均高于非钙化组(均P0.05)。经多因素Logistic回归分析可得:年龄、透析时间、hs-CRP均是MHD患者血管钙化的独立危险因素(均P0.05)。结论:MHD患者CKD-MBD患病情况不容乐观,多见于高PTH、高磷血症、低钙血症。其中年龄、透析时间、hs-CRP均与MHD患者血管钙化密切相关,值得临床重点关注。     

百令胶囊联合左卡尼汀对维持性血液透析患者氧化应激、T淋巴细胞亚群及营养状态的影响*

目的:探讨百令胶囊联合左卡尼汀对维持性血液透析(MHD)患者氧化应激、T淋巴细胞亚群及营养状态的影响。方法:选取我院于2015年6月至2017年4月期间接受MHD治疗的慢性肾衰竭患者72例为研究对象。按照数表法将患者随机分为对照组(n=36)和实验组(n=36)。两组患者均行MHD治疗,实验组患者在此基础上给予百令胶囊联合左卡尼汀治疗,疗程均为6个月。比较两组治疗前、治疗6个月后的氧化应激指标:血浆丙二醛(MDA)、血浆谷胱甘肽过氧化物酶(GSHPx)、血浆总高半胱氨酸(tHcy)水平,免疫功能指标:CD3~+、CD4~+、CD8~+、CD4~+/CD8~+,营养状态指标:血红蛋白(Hb)、白蛋白(Alb)、前白蛋白(PA)、总胆固醇(TCh)、三酰甘油(TG)、脂蛋白(a)[Lp(a)]。结果:两组患者治疗6个月后MDA、t Hcy水平下降,且实验组低于对照组(P0.05);治疗6个月后实验组患者GSHPx水平高于治疗前与对照组(P0.05),而对照组GSHPx水平与治疗前相比差异无统计学意义(P0.05)。治疗6个月后,实验组患者CD3~+、CD4~+、CD4~+/CD8~+水平高于治疗前及对照组,而CD8~+低于治疗前及对照组(P0.05)。实验组治疗6个月后Hb、Alb、PA水平高于治疗前及对照组,而Lp(a)低于治疗前及对照组(P0.05),实验组患者TCh、TG水平与治疗前比较差异无统计学意义(P0.05);对照组治疗6个月后Hb、Alb、PA、TCh、TG、Lp(a)水平与治疗前比较差异均无统计学意义(P0.05)。结论:百令胶囊联合左卡尼汀可减轻MHD患者氧化应激反应,调节T淋巴细胞亚群,同时改善患者营养状况,值得临床推广应用。     

RFPL4A Increases the G1 Population and Decreases Sensitivity to Chemotherapy in Human Colorectal Cancer Cells

Cell cycle-arrested cancer cells are resistant to conventional chemotherapy that acts on the mitotic phases of the cell cycle, although the molecular mechanisms involved in halting cell cycle progression remain unclear. Here, we demonstrated that RFPL4A, an uncharacterized ubiquitin ligase, induced G₁ retention and thus conferred decreased sensitivity to chemotherapy in the human colorectal cancer cell line, HCT116. Long term time lapse observations in HCT116 cells bearing a “fluorescence ubiquitin-based cell cycle indicator” identified a characteristic population that is viable but remains in the G₁ phase for an extended period of time (up to 56 h). Microarray analyses showed that expression of RFPL4A was significantly up-regulated in these G₁-arrested cells, not only in HCT116 cells but also in other cancer cell lines, and overexpression of RFPL4A increased the G₁ population and decreased sensitivity to chemotherapy. However, knockdown of RFPL4A expression caused the cells to resume mitosis and induced their susceptibility to anti-cancer drugs in vitro and in vivo. These results indicate that RFPL4A is a novel factor that increases the G₁ population and decreases sensitivity to chemotherapy and thus may be a promising therapeutic target for refractory tumor conditions.     

小鳞鱼箴的维持日粮与转换效率

1998年 8月在一个养虾场蓄水池利用网箱进行了小鳞鱼箴维持日粮与转换效率的研究 .小鳞鱼箴生长率(GR)与日粮 (DR)的关系可表示为GR =14 0 .37DR -2 4.0 3 ;食物转换效率和能量转换效率分别为 13 .96 %和16 .12 % .从生长率和特定生长率计算的小鳞鱼箴维持日粮分别为体重的 17.12 %和 2 0 .39% ,表明从生长率和特定生长率计算维持日粮可能会导致不同的结果 .当日粮水平低于 3 .30 %时 ,小鳞鱼箴生长表现异常 ,意味着它可能利用了网采浮游动物以外的其它食物源 .     

老年营养风险指数联合血清铁蛋白水平对维持性血液透析患者腹主动脉钙化风险的预测价值

摘要 目的：探讨老年营养风险指数（GNRI）联合血清铁蛋白（SF）水平对维持性血液透析患者腹主动脉钙化（AAC）风险的预测价值。方法：选取2020年3月-2022年4月安徽省铜陵市人民医院收治的112例维持性血液透析患者,根据有无合并AAC分为钙化组（n=63）与未钙化组（n=49）,比较两组临床资料、GNRI、血清SF水平。根据AAC评分将钙化组分为轻度钙化组（n=24）、中度钙化组（n=21）与重度钙化组（n=18）,比较三组GNRI、血清SF水平。采用Pearson相关性分析法分析钙化患者GNRI、血清SF水平与AAC评分的相关性;采用多因素Logistic回归模型分析AAC发生的影响因素,采用受试者工作特征（ROC）曲线分析GNRI、血清SF对维持性血透患者发生AAC风险的预测价值。结果：钙化组年龄大于未钙化组,白蛋白水平及GNRI低于未钙化组,透析时间长于未钙化组,低密度脂蛋白胆固醇、血磷、全段甲状旁腺素（iPTH）、血清SF水平高于未钙化组（P＜0.05）。轻、中、重度钙化组GNRI依次下降,血清SF水平依次上升（P＜0.05）。Pearson相关性显示,GNRI与AAC评分呈负相关,SF水平与其呈正相关（P＜0.05）。多因素Logistic结果显示,透析时间增加、血磷、iPTH、血清SF水平上升,白蛋白水平下降与GNRI分值降低为AAC发生的危险因素（P＜0.05）。ROC曲线显示,GNRI对AAC预测的曲线下面积（AUC）为0.744,血清SF的AUC为0.769,两者联合检测的AUC为0.844,GNRI的灵敏度与特异度为58.72%、77.66%,SF的灵敏度与特异度为85.75%、73.51%,两者联合检测的灵敏度与特异度为84.10%、79.67%。结论：GNRI下降及血清SF水平上升为维持性血透患者发生AAC的危险因素,与钙化程度密切相关,两者联合检测作为预测患者发生AAC风险的有效指标具有更高价值。     

The role of carbon dioxide in glucose metabolism of Bacteroides fragilis

The effect of CO₂ concentration on growth and glucose fermentation of Bacteroides fragilis was studied in a defined mineral medium. Batch culture experiments were done in closed tubes containing CO₂ concentrations ranging from 10% to 100% (with appropriate amounts of bicarbonate added to maintain the pH at 6.7). These experiments revealed that CO₂ had no influence on growth rate or cell yield when the CO₂ concentration was above 30% CO₂ (minimum available CO₂–HCO ₃ ^- , 25.5 mM), whereas a slight decrease in these parameters was observed at 20% and 10% CO₂ (available CO₂–HCO ₃ ^- , 17 and 8.5 mM, respectively). If CO₂–HCO ₃ ^- concentrations were below 10 mM, the lag phase lengthened and a decrease in maximal growth rate and cell yield were observed. The amount of acetate made decreased, while d-lactate concentration increased. A net production of CO₂ allowed growth under conditions of extremely low concentrations of added CO₂.When B. fragilis was grown in continuous culture with 100% CO₂ or 100% N₂, the dilution rate influenced the concentrations of acetate, succinate, propionate, d-lactate, l-malate and formate formed. Decreasing the dilution rate favored propionate and acetate production under both conditions. When the organism was grown with 100% N₂, the amount of propionate formed was greater than the amount of succinate formed at all dilution rates. Except at slow dilution rates the reverse was true when 100% CO₂ was used. B. fragilis was unable to grow at dilution rates faster than 0.154 h^-1 when grown with 100% N₂; the Y _glc ^max was 67.9 g DW cells/mol glucose and m _s was 0.064 mmol glucose/g DW·h. If the gas atmosphere was 100% CO₂ the organism was washed out of the culture when the dilution rate exceeded 0.38 h^-1; the Y _glc ^max was 59.4 g DW cells/mol glucose and m _s was 0.094 mmol glucose/g DW·h.Measurement of the phosphoenolpyruvate (PEP) carboxykinase (E.C. 4.1.1.49) with whole, permeabilized cells of B. fragilis showed an increase of specific enzyme activity with decreasing CO₂ concentrations. The mechanisms used by B. fragilis to adjust to low levels of CO₂ are discussed.