生物安全三级实验室核心区排风高效空气过滤器原位消毒的研究

<实验室生物安全通用要求>(GB19489-2008)要求生物安全三级实验室"应可以在原位对排风高效空气(HEPA)过滤器进行消毒灭菌".BSL-3实验室核心区排风HEPA过滤器是保证实验操作过程中产生的感染性气溶胶不外泄的最后防线,为了保障环境安全,需在原位实现HEPA过滤器的消毒.本研究设计并制作了循环消毒样机,与排风HEPA过滤器排风箱体的消毒接口连接,利用循环气流带动甲醛蒸汽循环实现原位消毒.结果显示,室温条件下甲醛蒸汽浓度16 mg/L,相对湿度70%,持续熏蒸循环穿透运行12 h,布置于HEPA过滤器排风箱体内用于指示消毒效果的金黄色葡萄球菌、耻垢分枝杆菌、枯草芽胞杆菌及嗜热脂肪芽胞杆菌均被完全杀灭,从设备及方法学两方面实现了排风HEPA过滤器的原位消毒.     

过氧化氢预处理对褐煤物化性质及生物产气的影响

【目的】研究过氧化氢预处理对褐煤物化性质及生物产气的影响。【方法】以胜利5号褐煤为研究对象,利用正交试验对过氧化氢预处理褐煤条件进行优化,在最优条件下处理褐煤得到处理后的残煤和处理液,通过X射线衍射分析(X-ray diffraction, XRD)、扫描电镜分析(scanning electron microscopy, SEM)、比表面积分析及孔隙分析(brunauer-emmett-teller, BET)、气相色谱-质谱分析(GC-MS)、高效液相色谱分析(HPLC)等方法对原煤、残煤和处理液的物化性质进行比较分析。【结果】经过氧化氢预处理,褐煤的最优条件为过氧化氢浓度5.0%、预处理时间20 d、液固比30:1,处理液中总有机碳含量为105 mg/L。在最优条件下,过氧化氢处理后残煤表面裂痕、凹陷增多,表面结构变得松散;煤的芳香面网间距增加,芳环结构更加疏松,晶核结构变小;孔隙度和比表面积均增大。处理后残煤中的固定碳、C元素和镜质组的相对含量降低,而灰分、挥发分、O和H元素及惰质组含量增加,残煤中O=C-O、C=C、C=O官能团含量增加,而N-H、C-H官能团含量则减少。生物产气结果表明反应液和残煤产气量均低于原煤,分别减少了39.13%和94.46%。过氧化氢预处理主要作用于煤中镜质组,使其有机碳溶解,煤中大分子结构的官能团发生变化,改变煤的芳环结构,在氧化作用下煤结构中的小分子溶解进入处理液。处理液中有机物以短链脂肪酸为主。经生物产气后,反应液中小分子酸以及有机物种类减少,被微生物利用产气。而各产气试验组中优势菌门及优势菌属的菌群丰度呈现出显著差异,古菌中原煤产气组盐杆菌门(Halobacteriota)为优势菌门,甲烷八叠球菌属(Methanosarcina)为优势菌属;反应液产气组热变形菌(Thermoprotei)为优势菌门,深古菌属(Bathyarchaeia)为优势菌属;细菌中原煤产气组放线菌门(Actinomycetota)为优势菌门,Gaiellales为优势菌属;反应液产气试验组假单胞菌门(Pseudomonadota)为优势菌门,代尔夫特菌属(Delftia)为优势菌属。【结论】煤溶解有机碳可以被微生物利用产气,但是煤中有机组分的过氧化脱除导致生物产气量减少。     

植物材料表面消毒方法的改进

苹果枝条用０．１％ＨｇＣＩ2磁力搅拌消毒１５-２０ｍｉｎ,无菌水磁力搅拌清洗５次,每次５ｍｉｎ。污染率和杀死率在１０％以下,成功率９０％左右,且无褐化。     

二氧化氯对小水榕外植体消毒效果研究

选取小水榕的绿芽和粗壮嫩芽组织为外植体,研究不同浓度ClO₂对外植体的消毒效果。结果表明:等于或高于500 mg/L的ClO₂溶液能迅速破坏小水榕成熟组织的绿色素;ClO₂溶液浸泡后未经无菌水冲洗的外植体污染率低,但生长缓慢,难以分化丛芽;以粗壮嫩芽组织为外植体的材料经ClO₂或HgCl₂溶液浸泡灭菌都可获得无菌外植体,建立有效的快繁体系。     

乙基纤维素微胶囊对过氧化氢酶固定化的研究

以乙基纤维素作膜材,用液中干燥法使过氧化氢酶微胶囊化。研究了微胶囊化操作条件对酶活性的影响。通过测定微胶囊化酶的释放曲线,证明微胶囊膜对过氧化氢酶具有较好的固定性能力。固定化酶用于催化底物过氧化氢分解,测定米氏常数为０．５５ｍｏｌ／Ｌ。     

甲醇对酵母过氧化氢酶活性的影响机理研究

将酵母过氧化氢酶加入一定比例的甲醇,测定其活性变化。结果表明:在含2%甲醇时酶活比对照提高4026%。将粗酶液用70%饱和度的硫酸铵盐析后离心所得的上清液再加入硫酸铵至80%饱和度,离心的沉淀溶解在缓冲液中,上SephadexG75柱,分离出的有酶活性的蛋白峰经电泳得一条蛋白带,说明过氧化氢酶已经被提纯到电泳纯。光谱分析发现,甲醇处理后过氧化氢酶纯酶的吸收光谱和荧光发射光谱与未经处理的比较基本不变,而差示光谱出现明显的正峰和负峰。由动力学分析可知,在甲醇中,过氧化氢酶的Vmax和Km值均有不同程度提高 。     

高压静电场对过氧化氢酶的稳定作用及机理研究

用高压静电场直接处理过氧化氢酶溶液 ,结果表明 :不同强度的高压静电场能提高和降低过氧化氢酶的活力。电场强度越大 ,酶活力达到平衡所需时间越短。处理后的过氧化氢酶溶液 ,玻棒 30秒的搅拌作用能使酶活力基本上回到原来的状态。溶液极性降低 ,酶活力达到平衡所需时间减少。处于高压静电场中的过氧化氢酶溶液 ,在 2 0℃时 ,电场强度为 3× 10 3V/cm ,活力能保持 5～ 6天 ,而对照只能保持 2～ 3天。在 30℃时 ,同样电场强度下 ,活力能保持 48小时左右 ,对照能保持 2 4小时左右。经高压静电场处理的酶 ,活力保持时间也比对照长。研究表明 :高压静电场对酶活力的稳定作用很可能是高压静电场使酶及溶液发生极化作用产生的。     

低温对植物叶片中超氧物歧化酶、过氧化氢酶和过氧化氢水平的影响

番茄和鸡蛋果叶片中可提取的SOD活性不受低温的影响。在电泳谱带上SOD主同工酶带被氰化物而不被低温抑制,次同工酶带在低温下不稳定,且活性很低,它的变化不影响总的SOD活性。一些冷敏感植物叶片中CAT活性被低温抑制,而H_2O_3水平在低温下稳定或有增加,这可能使毒性更强的羟基离子(OH·)易于形成。     

藻类产生及清除过氧化氢的研究

过氧化氢的生物生成是天然水体中H2O2的来源之一。从藻类产生及分解过氧化氢的途径,影响过氧化氢产量的主要因素,如藻的种类、细胞的渗透性、藻的生长阶段、藻浓度和光照条件等几方面对这一领域的研究作了综述。     

Caspases are reversibly inactivated by hydrogen peroxide

Hydrogen peroxide (H₂O₂) is known to both induce and inhibit apoptosis, however the mechanisms are unclear. We found that H₂O₂ inhibited the activity of recombinant caspase-3 and caspase-8, half-inhibition occurring at about 17 μM H₂O₂. This inhibition was both prevented and reversed by dithiothreitol while glutathione had little protective effect. 100–200 μM H₂O₂ added to macrophages after induction of caspase activation by nitric oxide or serum withdrawal substantially inhibited caspase activity. Activation of H₂O₂-producing NADPH oxidase in macrophages also caused catalase-sensitive inactivation of cellular caspases. The data suggest that the activity of caspases in cells can be directly but reversibly inhibited by H₂O₂.     

Oxidation of Good's buffers by hydrogen peroxide

Good's zwitterionic buffers are widely used in biological and biochemical research in which hydrogen peroxide is a solution component. This study was undertaken to determine whether Good's buffers exhibit reactivity toward H(2)O(2). It is found that H(2)O(2) oxidizes both morpholine ring-containing buffers (e.g., Mops, Mes) and piperazine ring-containing zwitterionic buffers (e.g., Pipes, Hepes, and Epps) to produce their corresponding N-oxide forms. The percentage of oxidized buffer increases as the concentration of H(2)O(2) increases. However, the rate of oxidation is relatively slow. For example, no oxidized Mops was detected 2h after adding 0.1M H(2)O(2) to 0.1M Mops (pH 7.0), and only 5.7% was oxidized after 24h exposure to H(2)O(2). Thus, although all of these buffers can be oxidized by H(2)O(2), their slow reaction does not significantly perturb levels of H(2)O(2) in the time frame and at the concentrations of most biochemical studies. Therefore, the previously reported rapid loss of H(2)O(2) produced from the ferroxidase reaction of ferritin is unlikely due to reaction of H(2)O(2) with buffer, a conclusion supported by the fact that H(2)O(2) is also lost rapidly when the solution pH of the ferroxidase reaction is controlled by a pH stat apparatus in the absence of buffer.     

Action of 1,1-dimethylhydrazine on bacterial cells is determined by hydrogen peroxide

Seven different recombinant bioluminescent strains of Escherichia coli containing, respectively, the promoters katG and soxS (responsive to oxidative damage), recA (DNA damage), fabA (membrane damage), grpE, and rpoE (protein damage) and lac (constitutive expression) fused to the bacterial operon from Photorhabdus luminescens, were used to describe the mechanism of toxicity of 1,1-dimethylhydrazine (1,1-DMH) on bacteria, as well as to determine whether bacteria can sensitively detect the presence of this compound. A clear response to 1,1-DMH was observed only in E. coli carrying the katG’::lux, soxS’::lux, and recA’::lux-containing constructs. Preliminary treatment with catalase of the medium containing 1,1-DMH completely diminished the stress-response of the P_katG, P_recA, and P_soxS promoters. In the strain E. coli (pXen7), which contains a constitutive promoter, the level of cellular toxicity caused by the addition of 1,1-DMH was dramatically reduced in the presence of catalase.It is suggested that the action of 1,1-DMH on bacterial cells is determined by hydrogen peroxide, which is formed in response to reduction of the air oxygen level.     

产H_2O_2的乳酸杆菌分离培养基的改良

对MRS培养基的使用方法进行了改良。将MRS(含0.25 mg/ml TMB)融化后倾倒入平皿,待其凝固后,在琼脂表明加入200μl(0.01 mg/ml)HRP,涂匀后进行乳酸杆菌划线分离。37℃、厌氧培养48~72 h。结果表明,产生H2O2的乳酸杆菌呈蓝色菌落,和原来的培养方法相比,改良的方法简便经济、HPR的使用量为原来的1%,分离产H2O2的乳酸杆菌的效果良好。     

Vanadium catalyzed oxidation with hydrogen peroxide

Vanadium peroxides are known as very effective oxidants of different organic and inorganic substrates. In this short account reactivity, structural and mechanistic studies concerning the behaviour of peroxovanadates toward a number of different substrates are collected. Homogeneous and two-phase systems are presented, in addition, interesting synthetic results obtained with the use of ionic liquids as reaction media are also presented.     

Inhibition of hydrogen peroxide release from activated macrophages by prior ingestion of erythrocytes or haemoglobin

Abstract Production of hydrogen peroxide by mouse peritoneal macrophages activated with Corynebacterium parvum was induced by incubating the cells with opsonised zymosan. H₂O₂ release was reduced by 47% when macrophages were preincubated with opsonised sheep erythrocytes. A significant decrease also occurred when the cells were preincubated with heat-denatured haemoglobin, but not when preincubated with opsonised erythrocyte ghosts, even though the latter were taken up by the macrophages. The ability of macrophages in an infected lesion to destroy microorganisms may therefore be impaired by ingestion of extravasated erythrocytes.     

Stabilization of Snail by HuR in the process of hydrogen peroxide induced cell migration

Snail functions as a key regulator in the induction of a phenotypic change called epithelial to mesenchymal transition (EMT). Aberrant expression of Snail prevails in the onset and development of tumor. Here, we have observed increased expression of Snail under the treatment of hydrogen peroxide (H(2)O(2)). Investigation into the underlying mechanisms revealed that stabilization of Snail mRNA contributes partially to this process. H(2)O(2)-induced the luciferase activity of the reporter construct contains the 3'UTR of Snail. Deletion of the AU-rich elements in the UTR eliminated the response of the reporter to H(2)O(2), suggesting the potential role of HuR in the process. Lowering of endogenous HuR levels through knockdown of HuR by siRNA greatly reduced the inducability and half-life of Snail mRNA, which consequently inhibited the downregulation of E-cadherin by H(2)O(2). Our findings indicate that HuR plays a major role in regulating H(2)O(2)-induced Snail expression by enhancing Snail mRNA stability, which in turn enhances cell migrating ability through repressing expression of E-cadherin.     

Activity of magnetite-immobilized catalase in hydrogen peroxide decomposition

The present work analyzes the activity in decomposition of H₂O₂ using magnetite-immobilized catalase. The support of catalase is a glutaraldehyde-treated magnetite (Fe₃O₄). The data obtained in the H₂O₂ decomposition are analyzed. The fitting of the initial rate of the H₂O₂ decomposition versus hydrogen peroxide concentration data is discussed using a specific program for enzyme kinetics modeling (Leonora). The free catalase from Aspergillus niger (3.5 or 10 U/mL) does not show substrate inactivation up to 0.4 M H₂O₂. The immobilized catalase at low catalyst concentration shows substrate inhibition. Using 1 mg/mL of supported catalase the predicted maximum activity is higher than in the case of the free catalase at similar catalase concentration, although the optimum temperature is lower (40 °C versus 60 °C).     

Chemiluminescence in the reaction of cytochrome c with hydrogen peroxide

(1) Aqueous solutions of 1–10 μM ferricytochrome c treated with 100 μM–100 mM H₂O₂ at pH 8.0 emit chemiluminescence with quantum yield $\text{Ф ? 10}{}^{\mathrm{?9}}$ and absolute maximum intensity $\text{I}{}_{\mathrm{<mtext>max</mtext>}}\text{? 10}{}^5\text{hv/}\text{s}$ per cm³ (λ = 440), and exhibit exponential decay with a rate constant of 0.15 s^?1. (2) The emission spectrum of the chemiluminescence covers the range 380–620 nm with the maximum at 460 ± 10 nm. (3) Neither cytochrome c nor haemin fluoresce in the spectral region of the chemiluminescence. In the reaction course with H₂O₂, a weak fluorescence in the region 400–620 nm with λ_max = 465–510 nm (λ_exc 315–430 nm) gradually arises. This originates from tryptophan oxidation products of the formylkynurenine type or from imidazole derivatives, respectively. (4) Frozen solutions (77 K) of cytochrome c exhibit phosphorescence typical of tryptophan (λ_exc = 280 nm, λ_em = 450 nm). During the peroxidation, an additional phosphorescence gradually appears in the range 480–620 nm with λ_max = 530 nm (λ_exc = 340 nm). This originates from oxidative degradation products of tryptophan. (5) There are no red bands in the chemiluminescence spectra of cytochrome c or haemin. This result suggests that singlet molecular oxygen $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{<mtext>g</mtext>}}\text{)}$ is not involved in either peroxidation or chemiluminescence. (6) The haem Fe³⁺ group and H₂O₂ appear to be crucial for the chemiluminescence. It is suggested that the generation of electronically excited, light-emitting states is coupled to the production of conformational out-of-equilibrium states of peroxy-Fe-protoporphyrin IX compounds.     

Cytochemical localization of hydrogen peroxide generating sites in the rat thyroid gland

Sites of H₂O₂ generation in lightly prefixed, intact thyroid follicles were studied by two cytochemical reactions: peroxidase-dependent DAB oxidation and cerium precipitation. In both cases reaction product accumulated on the apical surface of the follicle cell at the membrane-colloid interface. The former reaction was inhibited by the peroxidase inhibitor, aminotriazole; both reactions were blocked by the presence of catalase. NADH in the medium slightly increased the amount of cerium precipitation. The ferricyanide technique for oxidoreductase activity was also applied; reaction product again was associated with the apical surface. These results strongly imply that the follicle cells have a NADH oxidizing system generating H₂O₂ at the apical plasma membrane.