不同病原学结果血流感染脓毒症患者PT、NLR、PCT/ALB的变化及其与预后的关系研究

摘要 目的：探讨不同病原学结果血流感染（BSI）脓毒症患者凝血酶原时间（PT）、中性粒细胞/淋巴细胞比值（NLR）、降钙素原/白蛋白（PCT/ALB）的变化及其与预后的关系。方法：选取2021年1月～2023年3月复旦大学附属上海市第五人民医院收治的BSI脓毒症患者130例,根据不同病原学结果分为真菌组11例、革兰阳性菌（G⁺菌）组49例、革兰阴性菌（G^-菌）组70例。根据28d临床结局将BSI脓毒症患者分为死亡组36例和存活组94例。检测并计算PT、NLR、PCT/ALB。采用多因素Logistic回归分析影响BSI脓毒症患者预后的因素,采用受试者工作特征（ROC）曲线分析PT、NLR、PCT/ALB对BSI脓毒症患者死亡的预测价值。结果：G^-菌组PT长于真菌组、G⁺菌组,NLR、PCT/ALB高于真菌组、G⁺菌组（P＜0.05）,真菌组与G⁺菌组PT、NLR、PCT/ALB比较无差异（P＞0.05）。多因素Logistic回归分析显示脓毒性休克、PT延长,序贯器官衰竭评估（SOFA）评分升高、急性生理和慢性健康评估Ⅱ（APACHEⅡ）评分升高、NLR升高、PCT/ALB升高为影响BSI脓毒症患者预后的独立危险因素（P＜0.05）。ROC曲线分析显示PT、NLR、PCT/ALB联合预测BSI脓毒症患者死亡的曲线下面积为0.897,大于PT、NLR、PCT/ALB单独预测（P＜0.05）。结论：相比真菌和G⁺菌,G^-菌BSI脓毒症患者PT、NLR、PCT/ALB明显升高,且PT、NLR、PCT/ALB升高是影响BSI脓毒症患者预后的独立危险因素,三者联合对BSI脓毒症患者预后的预测价值较高。     

内毒素、PCT联合NLR对经皮肾镜碎石术后患者尿源性脓毒血症的预测价值

摘要 目的：探讨内毒素、降钙素原（PCT）联合中性粒细胞与淋巴细胞比值（NLR）对经皮肾镜碎石术（PCNL）术后患者发生尿源性脓毒血症的预测价值。方法：选取2020年5月-2023年5月于西安医学院第二附属医院和空军军医大学第一附属医院泌尿外科行PCNL的患者750例作为研究对象。根据尿源性脓毒症发生情况分为尿源性脓毒血症组（n=45）和非脓毒血症组（n=705）。检测PCNL术前血清内毒素、PCT、中性粒细胞与淋巴细胞水平，并计算NLR。对比两组血清内毒素、PCT水平及NLR。采用多因素Logistic回归模型分析PCNL术后患者发生尿源性脓毒血症的影响因素。绘制受试者工作特征（ROC）曲线分析血清内毒素、PCT联合NLR预测PCNL术后患者发生尿源性脓毒血症的临床效能。结果：与非脓毒血症组相比，尿源性脓毒血症组血清内毒素、PCT及NLR更高（P<0.05）。多因素Logistic回归模型分析结果显示，血清内毒素升高、PCT升高、NLR升高、尿白细胞阳性、术前发热及鹿角型结石是PCNL术后患者发生尿源性脓毒血症的独立危险因素（P<0.05）；ROC曲线分析结果显示，血清内毒素、PCT联合NLR检测预测PCNL术后患者发生尿源性脓毒血症的曲线下面积（AUC）为0.913，高于上述各指标单独检测。结论：PCNL术前血清内毒素、PCT和NLR升高可能与术后患者发生尿源性脓毒血症有关。血清内毒素、PCT水平升高、NLR升高、术前发热、尿白细胞阳性、鹿角型结石是PCNL术后患者发生尿源性脓毒血症的危险因素。血清内毒素、PCT联合NLR检测对PCNL术后患者发生尿源性脓毒血症具有较高预测价值。     

中性粒细胞绝对值对脓毒血症并发肾损伤的早期诊断

摘要 目的：探讨中性粒细胞绝对值对脓毒血症并发肾损伤的早期诊断价值。方法：2016年1月-2020年6月选择在本院重点监护病房(Intensive care unit,ICU)和急诊科进行诊治的脓毒血症患者145例,测定与计算患者的中性粒细胞绝对值,调查患者的临床资料并进行早期诊断分析。结果：在145例患者中,发生肾损伤69例(肾损伤组),发生率为47.6 %。肾损伤组的年龄、性别、白细胞计数(white blood cell,WBC)计数、C反应蛋白(C reactive protein,CRP)、降钙素原(procalcitonin,PCT)、体重指数等与非肾损伤组对比差异无统计学意义(P>0.05)。肾损伤组的肌酐(Serum creatinine,Scr)和尿素氮(Blood urea nitrogen,BUN)、急性生理和慢性健康评分Ⅱ(acute physiology and chronic health evaluation II,APACHE Ⅱ)评分、序贯多器官功能障碍评分(sequential organ failure assessment,SOFA)都显著高于非肾损伤组(P<0.05)。肾损伤组的中性粒细胞绝对值都显著高于非损伤组(P<0.05)。logistic回归分析显示中性粒细胞绝对值、BUN、Scr、APACHE Ⅱ评分、SOFA评分都为影响肾损伤发生的主要独立因素(P<0.05)。结论：脓毒血症患者多伴随有肾损伤,可导致中性粒细胞绝对值升高,中性粒细胞绝对值也是导致脓毒血症并发肾损伤的主要因素,也具有重要的诊断价值。     

血清sTM、PCT、CRP/PAB比值与脓毒症患者APACHEⅡ评分、SOFA评分的相关性及其联合检测对预后的预测价值

摘要 目的：探讨血清可溶性血栓调节蛋白（sTM）、降钙素原（PCT）、C-反应蛋白与前白蛋白（CRP/PAB）比值与脓毒症患者急性生理和慢性健康评估Ⅱ（APACHEⅡ）评分、序贯器官衰竭评估（SOFA）评分的相关性及其联合检测对预后的预测价值。方法：选取2020年3月～2020年12月我院重症医学科收治的97例脓毒症患者,根据Sepsis-3.0诊断标准分为普通脓毒症组44例、脓毒性休克组53例,根据入院后30 d内预后情况分为死亡组35例和存活组62例。收集患者基线资料和APACHEⅡ评分、SOFA评分,并检测血清sTM、PCT、CRP/PAB比值。采用Spearman相关性分析脓毒症患者血清sTM、PCT、CRP/PAB比值与APACHEⅡ评分、SOFA评分的相关性,多因素Logistic回归分析脓毒症患者预后不良的影响因素,受试者工作特征（ROC）曲线分析血清sTM、PCT、CRP/PAB比值对脓毒症患者预后不良的预测价值。结果：脓毒性休克组血清sTM、PCT、CRP/PAB比值和APACHEⅡ评分、SOFA评分高于普通脓毒症组（P均＜0.05）。Spearman相关性分析显示,脓毒症患者血清sTM、PCT、CRP/PAB比值与APACHEⅡ评分、SOFA评分呈正相关（P＜0.05）。多因素Logistic回归分析显示,收缩压升高为脓毒症患者预后不良的独立保护因素（P＜0.05）,脓毒性休克、合并器官损伤≥3个、机械通气时间延长、APACHEⅡ评分增加、SOFA评分增加、sTM升高、PCT升高、CRP/PAB比值升高为独立危险因素（P均＜0.05）。ROC曲线分析显示,血清sTM、PCT、CRP/PAB比值联合预测脓毒症患者预后不良的曲线下面积大于各指标单独预测。结论：脓毒症患者血清sTM、PCT、CRP/PAB比值升高与APACHEⅡ评分、SOFA评分增加密切相关,血清sTM、PCT、CRP/PAB比值联合检测对脓毒症患者预后不良的预测价值较高。     

定量脑电图联合PLR、NLR、MPV/PLT比值在急性脑梗死静脉溶栓治疗疗效和短期预后评估中的临床应用价值

摘要 目的：探究定量脑电图联合血小板/淋巴细胞比值(PLR)、中性粒细胞/淋巴细胞比值(NLR)、血小板平均体积(MPV)/血小板计数(PLT)比值在急性脑梗死（ACI）静脉溶栓治疗疗效和短期预后评估中的临床应用价值。方法：选择2019年10月-2022年10月于长沙市第一医院收治的119例ACI患者为研究对象,根据静脉溶栓治疗疗效分为溶栓治疗有效组和溶栓治疗无效组,对比两组的功率比指数（DTABR）、PLR、NLR、MPV/PLT比值变化;根据ACI患者预后情况分为预后良好组与预后不良组,单因素分析比较两组基线临床资料,多因素Logistic回归模型分析ACI静脉溶栓预后影响因素,采用受试者工作特征曲线（ROC）分析各指标对ACI静脉溶栓预后的预测效能。结果：治疗后,溶栓治疗无效组DTABR、中性粒细胞计数、PLT、MPV、PLR、NLR、MPV/PLT比值显著高于溶栓治疗有效组（P＜0.05）,淋巴细胞计数显著低于溶栓治疗有效组（P＜0.05）。与预后良好组比较,预后不良组年龄、入院时美国国立卫生院神经功能缺损评分(NIHSS)评分、溶栓24 h后NIHSS评分、高血压史占比、DTABR、中性粒细胞计数、PLT、MPV、PLR、NLR、MPV/PLT比值显著升高（P＜0.05）,淋巴细胞计数显著降低（P＜0.05）。Logistic回归模型,显示入院时及溶栓24 h后NIHSS评分升高、DTABR升高、PLR升高、NLR升高、MPV/PLT比值升高是ACI静脉溶栓预后不良的危险因素（P＜0.05）。ROC曲线显示,DTABR、PLR、NLR、MPV/PLT比值联合预测ACI静脉溶栓预后的效能较高。结论：定量脑电图DTABR、PLR、NLR、MPV/PLT比值与ACI静脉溶栓治疗疗效和短期预后关系密切,对于短期预后有较高的预测价值。     

NLR、RDW和PCT评估老年社区获得性肺炎患者病情严重程度及预后的临床价值

摘要 目的：探讨中性粒细胞/淋巴细胞比值（NLR）、红细胞分布宽度（RDW）及降钙素原（PCT）在老年社区获得性肺炎（CAP）患者病情严重程度及预后评估中的临床价值。方法：回顾性分析2018年1月～2020年11月期间我院收治的127例老年CAP患者的临床资料,根据英国胸科协会改良肺炎评分(CURB-65)分为低危组（CURB-65评分＜3分,n=69例）和高危组（CURB-65评分≥3分,n=58例）;根据患者转归分为存活组（n=114例）和死亡组（n=13例）,比较各组患者的基线资料、NLR、RDW、PCT及其他实验室检查指标,并分析NLR、RDW、PCT与CURB-65评分的相关性以及预后的影响因素。结果：高危组NLR、RDW和 PCT水平均显著高于低危组,差异有统计学意义（P＜0.05）。经Pearson相关性分析可得：NLR、RDW、PCT与CURB-65评分均呈正相关关系（P＜0.05）。生存组患者白细胞计数（WBC）、中性粒细胞（NEU）、NLR、RDW、PCT和D-二聚体（D-Dimer）水平均低于死亡组,差异具有统计学意义（P＜0.05）,经多因素Logistic回归分析可得：NLR、RDW、PCT均是老年CAP患者预后的影响因素（均OR＞1,P＜0.05）。结论：NLR、RDW和PCT与CURB-65评分相关,且均是老年CAP患者预后的影响因素,NLR、RDW和PCT对老年CAP患者病情严重程度及预后具有一定的评估价值。     

共刺激分子CD86对急诊脓毒症发生的预测价值

摘要 目的：：探讨共刺激分子CD86评估急诊感染患者发生脓毒症的价值。方法：以2019年9月至2020年9月上海交通大学医学院附属仁济医院急诊科监护室和病房收治的年龄≥18岁且存在感染或临床高度怀疑感染的患者为研究对象。按照Sepsis-3.0标准,将患者分为脓毒症组和非脓毒症组。记录所有患者的临床资料,入院时24小时内检测所有患者的静脉血血常规、外周血单核细胞（PBMC）的CD86和HLA-DR表达水平、C反应蛋白（CRP）、降钙素原（PCT）、白蛋白（ALB）、乳酸(Lac)、血清白介素水平,计算CRP/ALB比值、中性粒细胞/淋巴细胞比值(NLR),血小板/淋巴细胞比值(PLR),淋巴细胞/单核细胞比值(LMR)并记录。组间比较上述各指标的差异,然后进一步采用Logistics回归模型进行多因素分析。结果：入选患者共91例,脓毒症患者49例（死亡15例,占30.6%）,非脓毒症患者42例（0死亡）;脓毒症组CD86%、N（中性粒细胞）、CRP/ALB、NLR、IL-6、IL-10、SIL-2R、CRP、PCT均高于非脓毒症感染（P<0.05）,而HLA-DR、LY（淋巴细胞）、PLT（血小板）、ALB、LMR在脓毒症组中则较非脓毒症组降低（P<0.05）。多因素Logistics回归分析建立CD86模型和HLA-DR模型,发现在CD86模型中,CD86,呼吸频率（RR）,LY,PCT是发生脓毒症的独立预测因子（P<0.05）,OR值分别为1.539(1.148-2.064),1.141(1.009-1.290),0.280(0.097-0.811)和1.036(1.005-1.068);在HLA-DR模型中,HLA-DR和LY是发生脓毒症的独立预测因子（P<0.05）,OR值分别为0.971(0.953-0.988)和0.290（0.117-0.718）。最后将CD86模型、HLA-DR模型和APACHII评分进行ROC曲线分析,曲线下面积（AUC）分别为0.870（0.796-0.944）、0.793（0.700-0.887）、0.754（0.653-0.855）。结论：脓毒症患者PBMC的CD86水平升高,HLA-DR水平降低,CD86和HLA-DR可以早期预测急诊脓毒症的发生。     

脓毒症患者血清降钙素原、C-反应蛋白与凝血功能、病情评分的关系及预后的影响因素分析

摘要 目的：探讨脓毒症患者血清降钙素原（PCT）、C-反应蛋白（CRP）与凝血功能、病情评分的关系及预后的影响因素。方法：选择2017年8月至2019年10月我院诊治的150例脓毒症患者作为研究对象,根据脓毒症组患者的生存状况将其分为存活组（n=118）和死亡组（n=32）。检测两组患者血清PCT、CRP水平,凝血酶原时间（PT）和部分凝血活酶时间（APTT）。采用急性生理功能和慢性健康状况评分系统Ⅱ(APACHEⅡ)和序贯器官衰竭估计(SOFA)对两组患者病情进行评估。比较两组患者临床资料。相关性分析采用Pearson检验。患者预后的影响因素采用多因素Logistic回归分析。结果：与存活组相比,死亡组血清PCT、CRP,PT、APTT,APACHE II和SOFA评分均明显升高（P<0.05）。血清PCT>7.32 ng/mL、CRP>86.73 ng/mL、PT>15.48s、APTT>36.74s、APACHE Ⅱ评分>15.88分和SOFA评分>6.48分均是脓毒症患者死亡的危险因素（OR=2.099、1.747、2.333、1.596、1.916、2.208,P<0.05）。血清PCT和CRP均与APACHE Ⅱ评分、SOFA评分、PT和APTT呈正相关（P<0.05）。结论：血清PCT和CRP水平升高与脓毒症患者死亡相关,两者与脓毒症患者APACHE Ⅱ评分、SOFA评分、PT和APTT存在正相关,并且是患者不良预后的影响因素,在脓毒症患者预后的评估中具有一定临床价值。     

系统性炎症指标预测脓毒性休克预后的临床价值

摘要 目的：探讨系统性炎症指标对脓毒性休克预后的临床预测价值。方法：回顾性分析2019年7月至2022年7月贵州省铜仁市石阡人民医院重症医学科救治的脓毒性休克患者46例（治疗组），46例患者随访60 d后根据临床预后分为存活组22例和死亡组24例。收集患者入院后治疗前血常规中白细胞、中性粒细胞、淋巴细胞、单核细胞和血小板计数，计算中性粒细胞与淋巴细胞比值（neutrophil-to-lymphocyte ratio，NLR）、血小板与淋巴细胞比值（platelet-to-lymphocyte ratio，PLR）、淋巴细胞与单核细胞比值（lymphocyte-to-monocyte ratio，LMR），同时记录生化中肌酐（Cr）、C反应蛋白（CRP）等指标，比较治疗后存活组和死亡组上述指标的差异，观察NLR、PLR、LMR与Cr水平的相关性。以Shapiro-Wilk检验进行正态性检验；Mann-Whitney U检验非正态分布的两组计数资料；相关性研究采用Spearman相关性分析；影响脓毒性休克预后的独立危险因素采用二分类logistic回归分析，并绘制生存曲线和受试者工作特征曲线（ROC曲线），评估危险因素预测脓毒性休克发生死亡事件的价值。结果：治疗组与正常对照组相比，入院时白细胞、中性粒细胞、淋巴细胞、单核细胞、血小板计数、NLR、PLR、LMR，差异有统计学意义（P＜0.01）。患者入院当天中性粒细胞、淋巴细胞、NLR、CRP在存活组与死亡组之间比较，差异有统计学意义（均P＜0.05），其余指标差异无统计学意义。脓毒性休克患者肌酐水平与NLR呈正相关（P＜0.01）。多因素logistic回归分析，结果显示仅有NLR是影响脓毒性休克患者60d预后的独立危险因素（OR=1.038，P= 0.031）。ROC曲线分析发现曲线下面积为0.705（95% CI: 0.597~0.812，P=0.001）；根据约登指数原则提示NLR预测死亡风险的截断值为16.35（敏感度为66.7%，特异度为72.7%），即NLR＞16.35时脓毒性休克的死亡率较高。Kaplan-Meier法分析治疗后60天生存预后，结果显示NLR≤16.35组中位生存期显著高于NLR＞16.35组，（χ²=5.568，P= 0.018）。结论：ICU初始NLR有助于脓毒性休克的病情判断并对患者生存预后评估有一定的临床价值，是发生死亡事件的独立预测指标。     

血清NGAL、GLI及NLR对脑卒中并发肺部感染患者预后的预测价值分析

摘要 目的：探究血清中性粒细胞明胶酶相关脂质蛋白（NGAL）、血糖不稳定指数（GLI）、中性粒细胞与淋巴细胞比值（NLR）对脑卒中并发肺部感染患者预后的预测价值。方法：选取2020年10月-2022年6月我院收治的98例脑卒中并发肺部感染患者，随访3个月，根据预后分为预后良好组67例与预后不良组31例，比较两组临床资料、实验室指标及血清NGAL、GLI、NLR水平，分析NGAL、GLI、NLR与临床肺部感染评分（CPIS）、美国国立卫生研究院卒中量表（NIHSS）评分、急性缺血性卒中相关性肺炎评分（AIS-APS）、肿瘤坏死因子-α（TNF-α）、超敏C反应蛋白（hs-CRP）、白细胞（WBC）计数的相关性，多因素Logistic回归分析脑卒中并发肺部感染患者预后不良的影响因素，受试者工作特征曲线（ROC）分析NGAL、GLI、NLR单独预测及联合预测脑卒中并发肺部感染患者预后不良的价值。结果：预后不良组住院时间、空腹血糖、CPIS评分、AIS-APS评分、NIHSS评分、TNF-α、hs-CRP、WBC显著高于预后良好组（P＜0.05）。预后不良组血清NGAL、GLI、NLR、中性粒细胞计数显著高于预后良好组（P＜0.05），淋巴细胞计数显著低于预后良好组（P＜0.05）。NGAL、GLI、NLR与CPIS评分、AIS-APS评分、NIHSS评分、TNF-α、hs-CRP、WBC均呈正相关（P＜0.05）。高NGAL、GLI、NLR、CPIS评分、NIHSS评分、TNF-α为脑卒中并发肺部感染患者预后不良的危险因素（P＜0.05）。NGAL、GLI、NLR联合预测脑卒中并发肺部感染患者预后不良的AUC为0.864，其价值显著优于各项指标单独检测（P＜0.05）。结论：血清NGAL、GLI、NLR在脑卒中并发肺部感染预后不良患者中升高较为显著，三者联合对于脑卒中并发肺部感染患者预后不良有较好的预测价值。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.