过氧化氢对白色念珠菌DNA破坏的研究

本文用热变性温度法研究一定浓度 H_2O_2对 C.albicans DNA 破坏作用。结果表明,经6%和10%H_2O_2处理后,C.albicans DNA G c Mol%(分别为28.1±0.82和14.4±1.51)显著低于对照 DNA G C Mol%(85.9±0.62),并推断 H_2O_2可能作用于 C.albicans DNA 碱基以及其间的氢键上;DNA 电泳图谱发现,经3%和6%H_2O_2处理的 C.albicans DNA 电泳带明显不同于对照,提示 H_2O_2更易造成 C.albicans DNA 核苷酸链的降解或断裂.H_2O_2对 C.albicans DNA 的破坏,增强了其杀菌作用。     

H^＋—ISFET的性能特点及应用研究

本文报道由我们研制的氢离子半导体传感器的性能特点，并与普通离子选择电极（玻璃电极）比较。Ｈ＾＋－ＩＳＦＥＴ具有体积小、取样少、快速、稳定、全固体化、不用预先活化等优点，对氢离子的敏感性也优于普通玻璃电极。本文还成功地将Ｈ＾＋－ＩＳＦＥＴ应用于有复杂成分并存的尿、血及其他生物材料的ｐＨ值测试，并改进胆碱酯酶活力测定方法，将Ｈ＾＋－ＩＳＦＥＴ应用于有机磷中毒后胆碱酯酶活力的快速定量测定。     

Monoamine oxidase inhibition as a sequel of hydrogen sulfide intoxication: increases in brain catecholamine and 5-hydroxytryptamine levels

Administration of sodium hydrosulfide (NaHS), an alkali salt of hydrogen sulfide (H₂S) at doses of 10 and 30 mg/kg, corresponding to sublethal and lethal doses (0.66 and 2.0 X LD₅₀) resulted in significant increases in regional catecholamine levels of the rat brain only after the dose of 2.0 × LD₅₀ of NaHS. Whereas the cortex and the cerebellum showed little or no change in catecholamine content, the hippocampus, striatum and brainstem all showed increases in noradrenaline and adrenaline. Additional analysis also showed that brainstem dopamine and 5-hydroxytryptamine levels (5-HT) increased as well. In vitro testing of sulfide for inhibition of monoamine oxidase (MAO) activity showed the anion to be inhibitory with an IC₅₀ of 39.1±3.6 M. Inhibition of MAO activity ex vivo could be demonstrated at a dose of 100 mg/kg but not at the lower dose of 30 mg/kg NaHS. Inhibition of enzyme activity could not be demonstrated at this lower dose, possibly due to the well known rapid intramitochondrial metabolism of sulfide. Correlation of synaptosomal and mitochondrial sulfide levels with enzyme inhibition data suggests that inhibition of MAO may be an important contributing factor to the mechanism(s) underlying loss of central respiratory drive after fatal intoxication with H₂S.     

Pigments of the Gastrointestinal Tract: A Comparison of Light Microscopic and Electron Microscopic Findings

It is now apparent that light microscopy and histochemistry failed to identify correctly the nature and composition of pigments in various gastrointestinal tract melanoses. In most instances it was thought that the pigment was melanin or a melanin-like substance. Electron microscopy (EM) and electron-probe energy dispersive x-ray analysis have rectified these errors and have shown the following: in melanosis coli the pigment granules contain lipofuscin; in melanoses ilei the pigment granules may contain either silicates and titanium or hemosiderin; and in melanosis duodeni the pigment granules contain iron sulfide. In melanosis esophagi it is not clear what the pigment is; it could be melanin or lipofuscin.     

萝摩甙抗自由基损伤作用的实验研究

目的:探讨萝摩甙对自由基所致脑损伤的神经元保护作用及机制。方法:复制脑缺血模型及H₂O₂诱导神经元损伤模型,分别测定大鼠脑组织、培养神经元中的丙二醛(MDA)含量以及培养神经元中的乳酸脱氢酶(LDH)漏出率、DNA断裂率和羟自由基清除率,观察萝摩甙对损伤神经元的保护作用。结果:萝摩甙可明显降低脑缺血造成的MDA的升高,亦可明显降低H₂O₂对神经元造成的LDH漏出率、DNA断裂率增加和丙二醛含量的升高,而且随着萝摩甙浓度的升高羟自由基清除率明显升高。结论:萝摩甙可通过清除自由基来保护神经元。     

Hydrogen peroxide mediates damage by xanthine and xanthine oxidase in cerebellar granule neuronal cultures

The free radical-generating system of xanthine and xanthine oxidase is commonly used experimentally as a source of superoxide anion, which can produce oxidative stress, leading to cellular damage and death. Models of oxidative stress are important in elucidating pathologies associated with increased levels of reactive oxygen species, including stroke and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. We therefore, examined the effect of the xanthine/xanthine oxidase system on the viability of postnatal cerebellar granule neurones obtained from 8-day old Sprague–Dawley rat pups. Xanthine (100 μM) and xanthine oxidase (0.02 U/ml) applied for 1 or 6 h reduced the viability of cells at 8 div assessed using the alamar blue assay, and induced morphological changes, such as shrinkage of the cell bodies and neurites. Heat-inactivation of xanthine oxidase resulted in complete loss of its activity. Superoxide dismutase (250 U/ml) failed to modify the damage by xanthine and xanthine oxidase, while catalase (250 U/ml) completely prevented it. When applied alone, xanthine oxidase significantly lowered cell viability, an effect that was blocked by allopurinol and catalase, but not by superoxide dismutase. The results indicate that xanthine and xanthine oxidase can produce predominantly hydrogen peroxide instead of the superoxide anion. Cerebellar granule cells in culture may also possess significant levels of endogenous xanthine.     

管花苷B对抗H2O2诱导的PC12细胞凋亡

目的：观察肉苁蓉提取物管花苷B对H₂O₂诱导的PC12细胞损伤的影响。方法：用MTT法检测细胞存活率，以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化，DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生，并用荧光酶标仪测定caspase-3的活性。结果：100 μmol·L^-1 H₂O₂处理细胞24 h显著降低细胞的存活率；诱导细胞发生凋亡，凋亡率达48.0％；细胞内活性氧水平及caspase-3的活性显著升高；而线粒体膜电位却明显降低，红/绿荧光强度的比值由正常的5.97降低为0.41左右。而预先给予1、10或100 mg·L^-1浓度的管花苷B处理细胞12 h，可显著提高细胞存活率；并可有效抑制DNA ladder的发生；流式细胞仪检测凋亡率分别降低到30.9%、18.3%和6.2%；激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平；并可逐渐恢复线粒体的高能量状态；caspase-3的活性不断降低，并呈现了一定的剂量依赖性。结论：管花苷B能显著地抑制H₂O₂诱导的PC12细胞凋亡，其神经细胞保护作用可能与其降低细胞内活性氧水平，维持线粒体膜电位的高能状态和抑制caspase-3的活性有关。     

Is there a role of taurine bromamine in inflammation? Interactive effects with nitrite and hydrogen peroxide

Objective and Design: The myeloperoxidase system of neutrophils generates chlorinating and brominating oxidants in vivo. The major haloamines of the system are taurine chloramine (TauCl) and taurine bromamine (TauBr). It has been demonstrated in vitro that TauCl exerts both antiinflammatory and anti-bacterial properties. Much less is known about TauBr. The present study was conducted to compare bactericidal and immunoregulatory capacity of TauBr with that of the major chlorinating oxidants: HOCl and TauCl. Moreover, the effect of nitrites and H₂O₂ on TauBr activity was investigated.Materials: TauBr was prepared by reaction of HOBr with taurine. The reaction was monitored by UV absorption spectra.Methods: Bactericidal activity of TauBr, TauCl and HOCl was tested by incubation of E. coli with the compounds and determined by the pour-plate method. To test the anti-inflammatory activity the compounds were incubated with LPS and IFN- stimulated murine peritoneal macrophages. The production of following mediators was measured: nitrites by Griess reaction; TNF-, IL-6, IL-10, IL-12p40 using capture ELISA. In some experiments the compounds were incubated with either nitrites or H₂O₂.Results: In our experimental set-up TauBr and HOCl exerted strong bactericidal effects on E. coli (MBC = 110 M and 8 M, respectively), while TauCl (< 1000 M) did not kill test bacteria. However, both, TauBr and TauCl, at noncytotoxic concentrations (< 300 M) inhibited the cytokine and nitric oxide production by macrophages. H₂O₂ completely abolished the biological activities of TauBr but not those of TauCl. Nitrites did not affect any activity of TauBr or TauCl while they diminished the HOCl^– mediated bacterial killing.Conclusion: TauBr, despite very low concentration of Br^– in body fluids, may support TauCl and HOCl in the regulation of inflammatory response and in killing of bacteria by neutrophils. However, TauBr activity in vivo will depend on the presence of H₂O₂ and possible other mediators of inflammation which can compete with target molecules for TauBr.Received 16 August 2004; returned for revision 16 September 2004; accepted by A. Falus 13 October 2004     

心血管组织钙化时内源性硫化氢系统下调

目的：观察心血管组织钙化时内源性硫化氢生成系统(CSE/H2S)的变化，以探讨内源性硫化氢在心血管组织钙化中的作用及血管钙化的细胞分子机制。方法：在维生素D3 (Vit D3)和尼古丁(nicotine)诱导大鼠血管钙化模型上，测定钙含量、［45Ca2+］沉积及碱性磷酸酶（ALP）活性判断心血管钙化程度,采用生化法测定血浆、心肌组织和主动脉H2S含量及CSE活性，半定量RT-PCR方法测定心血管组织CSE mRNA水平。结果：钙化组大鼠心肌组织钙含量较对照组高3.8倍,主动脉钙含量、［45Ca2+］ 沉积及ALP 活性分别较对照组高6.8倍、1.4倍和 1.9倍（P＜0.01）；钙化组大鼠血浆H2S含量较对照组低39%（P<0.01），心肌和主动脉组织的 H2S含量也分别较对照组低39%和31%，CSE mRNA表达也分别低28％和36％（P<0.01），CSE活性分别低56%和53%(P<0.01)。结论：钙化心血管组织CSE/H2S通路受抑制，内源性H2S生成减少。     

硫化氢对体外大鼠肝星状细胞内Ca2+浓度变化及细胞增殖的影响

目的 研究硫化氢(H₂ S)对大鼠肝星状细胞-T6(HSC-T6) Ca²⁺浓度、细胞增殖的影响及其机制。 方法 活化HSC-T6用含10%小牛血清DMEM培养液制备为1×10⁵个肝星状细胞(HSC)悬液。钙离子荧光探针Fluo-3/AM负载细胞后，在不同刺激条件下，利用激光扫描共焦显微镜动态扫描HSC-T6细胞内Ca²⁺荧光强度（FI）变化，FI表示细胞内Ca²⁺浓度。四唑盐比色法，观察不同浓度H₂S供体——NaSH对HSC-T6细胞增殖的影响。 结果 低浓度H₂S（100μmol/L）明显降低HSC-T6细胞内Ca²⁺浓度（P<0.05)，而细胞增殖增加（增殖率为116%）；K_ATP通道阻断剂——格列本脲可阻断H2S的作用。高浓度H₂S（1mmol/L）刺激HSC-T6细胞内Ca₂₊浓度增加，但细胞增殖无明显变化(P＞0.05)。 结论 低浓度H₂S通过激活HSC-T6细胞K_ATP通道降低细胞内Ca²⁺浓度，可能通过调节细胞氧化应激促进细胞增殖；高浓度H2S刺激HSC-T6细胞内Ca₂₊浓度增加。提示H₂S在肝硬化门脉高压症的发生机制中具有双重作用。