血链球菌在不同牙周状态下的分布及相关研究

目的：探讨口腔主要过氧化氢产生菌血链球菌和口腔链球菌在不同牙周健康状态下龈下菌群中的分布,及与牙周健康状态和牙龈卟啉单胞菌群中分布的相互关系。方法：纳入符合标准的受试者30人,受试位点86个,其中健康组11人,位点30个,龈炎组9人,位点29个,慢性牙周炎组10人,位点27个,检查记录牙周健康状态[包括牙龈指数（GI）和牙周袋深度（PD）],采集龈下菌斑标本,经厌氧菌培养基和AP-PCR及PCR鉴定后,将各受试组进行比较分析。结果：共获得草绿色链球菌523株,产黑色素菌241株。经AP-PCR及PCR鉴定后,得到血链球菌112株,口腔链球菌56株,牙龈卟啉单胞菌84株,健康组龈下菌斑中血链球菌,口腔链球菌和牙龈卟啉单胞菌构成比与牙周炎组相比有差异显著性;血链球菌和口腔链球菌与GI、PD呈负相关,牙龈卟啉菌与GI、PD呈正相关;血链球菌的构成与牙龈卟啉单胞菌的构成比呈负相关。结论：血链球菌等过氧化氢产生菌在龈下菌斑中比例的下降。可能是微生态失衡,致病菌过度增殖的重要机制。     

血链球菌拮抗可疑牙周病原菌机理探讨：Ⅱ细胞素的产生及…

血链球菌产生细菌素至培养上清液中,无论是需氧或厌氧环境,血链球菌均可产生血逻素。采用无水乙醇沉淀法提取血链球菌培养上清液中的蛋白质,运用ＳＤＳ－ＰＡＥＧ分析其蛋白成份,发现１３０ｋｄ、１２０ｋｄ、７４ｋｄ、和５６ｋｄ四条蛋白区带,通过电泳凝胶弥散法抑菌试验显示,５６ｋｄ蛋白带具很强的抑菌活性,提示此蛋白质可能为血链素的所在位置。     

ABA诱导蚕豆气孔保卫细胞H2O2的产生

以蚕豆叶片下麦皮为材料,将荧光探针ＨＰＴＳ导入蚕豆忆保卫细胞内,利用荧光光谱和激光共聚焦显微技术,检测了ＡＢＡ诱导蚕豆气孔关闭过程中Ｈ２Ｏ２的产生。结果表明,ＡＢＡ和１００μｍｏｌ／Ｌ的Ｈ２Ｏ２可以迅速猝灭ＨＰＴＳ的荧光,ＣＡＴ几乎可完全阻止９μｌ０．２ｍｍｏｌ／Ｌ的ＡＢＡ引起荧光猝灭。因此,ＡＢＡ可以诱导气孔保卫细胞产生Ｈ２Ｏ２,其产生的强度和速度与ＡＢＡ的浓度直接有关,并且推测：这种Ｈ２Ｏ２产     

ATP对中性粒细胞H2O2产生双重作用机制的研究

本文通过高压液相法测定ATP的代谢,探讨其对中性粒细胞H2O2产生双重作用的机制。结果显示,ATP本身不能激活中性粒细胞产生H     

植物细胞的氧化猝发和H2O2的信号转导

概述了植物细胞氧化猝发的特性、产生机理、生理作用以及Ｈ２Ｏ２信号转导途径及其对基因表达的调控等的研究进展。     

水分胁迫下苹果叶片的H2O2代谢

轻度水分胁迫下苹果叶片Pr迅速升高,CAT活性变化不大,NaHSO3处理能显著低叶内H2O2含量,表明光呼吸的加强促进了H2O2产生可能是叶内H2O2大量积累的主要原因;中度水分胁迫下叶片AsA含量的下降和ehler反应的增强都非常明显;DDTC和AsA处理都能有效降低叶内H2O2积累。但MV处理的作用不大,说明叶片H2O2主要来源于Mehler反应AsA降解造成叶片对H2O2清除能力的下降是其积累的根本原因;严重水分胁迫时,NaHSO3和DDTC都不能有效地减轻叶内H2O2积累,光呼吸和Mehler反应都可能不是H2O2的主要来源。     

H2O2和水杨酸对陈化马铃薯切片交换呼吸途径影响的比较

外源5.0mmol/L H2O2和0.1mmol/L水杨酸（salicylic acid,SA)处理均可明显提高陈化24h的马铃薯切片的交替呼吸途径容量（Valt)及其与总呼吸的比值（Valt/Vt)。应用交替氧化酶的单克隆抗体进行Western杂交的结果表明,H2O2和SA处理均可明显提高陈化马铃薯切片中交替氧化酶的表达水平。用氧同位素分辨法研究,结果表明：H2O2处理对陈化马铃薯切片中交替呼吸途径的实际运行没有影响,而SA处理对交替呼吸途径的实际运行具有明显的促进作用。上述结果表明,H2O2和SA对植物组织交替呼吸途径的影响存在差异,二均可促进交替氧化酶的表达从而诱导交替呼吸途径容量的发生,但H2O2不影响其实际运行,而SA还可同时诱导其实际运行。     

血链球菌产生过氧化氢机理研究

作者在国内首次建立两种确定细菌产生过氧化氦的方法,可以定性和定量分析。本文探讨了血链球菌产生过氧化氢的条件,研究其在牙周微生态环境中的作用。     

HYDROGEN PEROXIDE AND ECDYSONE IN THE CRYOPROTECTIVE DEHYDRATION STRATEGY OF Megaphorura Arctica (ONYCHIURIDAE: COLLEMBOLA)

The Arctic springtail, Megaphorura arctica, survives sub‐zero temperatures in a dehydrated state via trehalose‐dependent cryoprotective dehydration. Regulation of trehalose biosynthesis is complex; based in part on studies in yeast and fungi, its connection with oxidative stress caused by exposure of cells to oxidants, such as hydrogen peroxide (H₂O₂), or dehydration, is well documented. In this respect, we measured the amount of H₂O₂ and antioxidant enzyme activities (superoxide dismutases: copper, zinc—CuZnSOD and manganese containing–MnSOD, and catalase—CAT), as the regulatory components determining H₂O₂ concentrations, in Arctic springtails incubated at 5 °C (control) versus ?2 °C (threshold temperature for trehalose biosynthesis). Because ecdysone also stimulates trehalose production in insects and regulates the expression of genes involved in redox homeostasis and antioxidant protection in Drosophila, we measured the levels of the active physiological form of ecdysone—20‐hydroxyecdysone (20‐HE). Significantly elevated H₂O₂ and 20‐HE levels were observed in M. arctica incubated at ?2 °C, supporting a link between ecdysone, H₂O₂, and trehalose levels during cryoprotective dehydration. CAT activity was found to be significantly lower in M. arctica incubated at ?2 °C versus 5 °C, suggesting reduced H₂O₂ breakdown. Furthermore, measurement of the free radical composition in Arctic springtails incubated at 5 °C (controls) versus ?2 °C by Electron Paramagnetic Resonance spectroscopy revealed melanin‐derived free radicals at ?2 °C, perhaps an additional source of H₂O₂. Our results suggest that H₂O₂ and ecdysone play important roles in the cryoprotective dehydration process in M. arctica, linked with the regulation of trehalose biosynthesis.     

蛭弧菌J26转化山梨糖生产2—酮基—L—古龙酸发酵条件的研究

对新分离得到的能产生维生素C前体2-酮基-L-古龙酸（2-KGA）的优良菌株蛭弧菌J26,进行了一系列摇瓶发酵条件试验,通过添加一些其它有机碳源或其它氮源,可使蛭弧菌J26摇瓶发酵产生2－KGA由50-60mg／ml上升到70mg／ml以上,采用SMA探针技术的流加发酵摇瓶试验产生2－KGA可以达到83．9－91．7mg／ml。本文还对发酵时种子液的接种量、发酵初始精浓度、初始pH值等对产酸的影响,进行了比较研究,对摇瓶发酵全过程的单一菌体形态特征进行了电子显微镜观察。     

STUDIES OF POLYSACCHARIDES FROM THREE EDIBLE SPECIES OF NOSTOC (CYANOBACTERIA) WITH DIFFERENT COLONY MORPHOLOGIES: STRUCTURAL CHARACTERIZATION AND EFFECT ON THE COMPLEMENT SYSTEM OF POLYSACCHARIDES FROM NOSTOC COMMUNE

The cyanobacterium Nostoc commune Vaucher produces quite complex extracellular polysaccharides. The cyanobacterium is nitrogen fixing, and on growing the cyanobacterium in media with and without nitrogen, different types of extracellular polysaccharides were obtained. These were also different from the polysaccharides present in N. commune collected in the field. High pH anion exchange chromatography (HPAEC) of weak acid hydrolysates of the culture-grown material demonstrated that, in this case, HPAEC was useful for comparison of the different polymers. The main differences between the polymers from the field group and the culture-grown samples were the presence of substantial amounts of arabinose, 2- O -methylglucose, and glucuronic acid in the latter. Methylation studies also revealed a difference in the branching points on the glucose units between the field and cultured samples, being 1,4,6 for the first and 1,3,6 for the latter. The field acidic fraction gave, on weak acid hydrolysis and separation on BioGel P2 and HPAEC, 12 oligosaccharide fractions that were isolated and studied by different mass spectroscopy techniques. The structures of the oligosaccharides were determined, and two different series that can originate from two repeating pentamers were identified: GlcA1-4/6GlcM1-4Gal1-4Glc1-4Xyl and GlcA1-4/6Glc1-4Gal1-4Glc1-4Xyl. The difference between these oligosaccharides lies in the methyl substituent on carbon 2 of the glucose unit next to the nonreducing glucuronic acid unit. The polysaccharides from field material were shown to have a strong effect on the complement system.