Ethanol metabolism in rat brain homogenates by a catalase-H2O2 system.

Homogenates of perfused rat brains incubated in the presence of ethanol (50-100 mM) and glucose (10 mM) were found to oxidize ethanol to acetaldehyde. The addition of glucose oxidase, a known hydrogen peroxide generator, to the incubation medium, significantly (P less than 0.05) increased the generation of acetaldehyde. The presence in the incubation medium of metyrapone, an inhibitor of cytochrome P450, or pyrazole, an alcohol dehydrogenase inhibitor, did not affect the levels of acetaldehyde obtained. Conversely, the presence of 3-amino-1,2,4-triazole, a known catalase inhibitor, induced a concentration-dependent reduction of the amount of acetaldehyde generated after incubation, even in the presence of glucose oxidase. Homogenates of perfused brains of rats treated with 3-amino-1,2,4-triazole or cyanamide (another H2O2-dependent catalase blocker) also showed a dose-dependent reduction of the acetaldehyde obtained. These findings support the notion that a catalase-mediated oxidation of ethanol is present in rat brain homogenates. It is suggested that this local oxidation of ethanol may have important biological implications. The data of both studies increase support for the notion that acetaldehyde is produced directly in the brain and that it may be the agent mediating some of the psychopharmacological properties of ethanol and be one of the factors determining the propensity of an animal to voluntarily consume ethanol.     

Comparative sterilization effectiveness of plasma in O2-H2O2 mixtures and ethylene oxide treatment

We investigated the influence of variable parameters of plasma sterilization and compared its effectiveness with that of ethylene oxide using a reactive ion etching plasma reactor at 13.56 MHz. Gases tested were pure oxygen and oxygen-hydrogen peroxide mixtures in 190/10, 180/20, and 160/40 sccm ratios with constant gas flow at 200 sccm, pressure at 0.100 torr, radio-frequency power at 25 W, 50 W, 100 W, and 150 W, and temperature below 60 degrees C. Ethylene oxide sterilization was performed using 450 mg/L at 55 degrees C, 60% humidity, and -0.65 and 0.60 kgf/cm2 pressure. The biological indicator was Bacillus atrophaeus ATCC 9372, with exposure times of 3 to 120 min. Observed D values were 215.91, 55.55, 9.19, and 2.98 min for pure oxygen plasma at 25 W, 50 W, 100 W, and 150 W, respectively. Oxygen-hydrogen peroxide plasma produced D values of 6.41 min (190/10), 6.47 min (180/20), and 4.02 min (160/40) at 100 W and 1.47 min (190/10), 3.11 min (180/20), and 1.94 min (160/40) at 150 W. Ethylene oxide processes resulted in a D value of 2.86 min. Scanning electron microscopy analyses showed damage to the spore cortex.     

Pulmonary toxicity of Fe2O3, ZnFe2O4, NiFe2O4 and NiZnFe4O8 nanomaterials: Inflammation and DNA strand breaks

Exposure to metal oxide nanomaterials potentially occurs at the workplace. We investigated the toxicity of two Fe-oxides: Fe₂O₃ nanoparticles and nanorods; and three MFe₂O₄ spinels: NiZnFe₄O₈, ZnFe₂O₄, and NiFe₂O₄ nanoparticles. Mice were dosed 14, 43 or 128 μg by intratracheal instillation. Recovery periods were 1, 3, or 28 days. Inflammation – neutrophil influx into bronchoalveolar lavage (BAL) fluid – occurred for Fe₂O₃ rods (1 day), ZnFe₂O₄ (1, 3 days), NiFe₂O₄ (1, 3, 28 days), Fe₂O₃ (28 days) and NiZnFe₄O₈ (28 days). Conversion of mass-dose into specific surface-area-dose showed that inflammation correlated with deposited surface area and consequently, all these nanomaterials belong to the so-called low-solubility, low-toxicity class. Increased levels of DNA strand breaks were observed for both Fe₂O₃ particles and rods, in BAL cells three days post-exposure. To our knowledge, this is, besides magnetite (Fe₃O₄), the first study of the pulmonary toxicity of MFe₂O₄ spinel nanomaterials.     

Endothelium dysfunction in LDL receptor knockout mice: a role for H2O2

1. In this study, the role of endogenous H(2)O(2) as an endothelium-dependent relaxant factor was characterised in aortas from C57BL/6J and LDL receptor-deficient mice (LDLR(-/-)). 2. Aortic rings from LDLR(-/-) mice showed impaired endothelium-dependent relaxation to acetylcholine (ACh; 0.001-100 micro M) and to the Ca(2+) ionophore A23187 (0.001-3 micro M) compared with aortic rings from control mice. Endothelium-independent relaxation produced by the NO donor, 3-morpholino-sydnonimine (SIN-1) was not different between strains. 3. Pretreatment of vessels with L-NNA (100 micro M) or L-NNA (100 micro M) plus L-NAME (300 micro M) plus haemoglobin (10 micro M) markedly decreased, but did not abolish the relaxation to ACh in control mice. In the aortas from LDLR(-/-) mice treated with L-NNA (100 micro M), ACh induced a contractile effect. Catalase (800 and 2400 U ml(-1)) shifted to the right the endothelium-dependent relaxation to ACh in aortas from control but not from LDLR(-/-) mice. Aminotriazole (50 mM), which inhibits catalase, abolished its effect on control mice. Treatment of vessels with L-NNA and catalase abolished vasorelaxation induced by ACh. Indomethacin (10 micro M) did not modify the concentration-response curve to ACh. Superoxide dismutase (300 U ml(-1)) did not change ACh-induced relaxation in both strains. 4. Exogenous H(2)O(2) produced a concentration-dependent relaxation in endothelium-denuded aortic rings, which was not different between strains. 5. It is concluded that H(2)O(2) greatly contributes to relaxation to ACh in aorta from control mice. Endothelial-dependent relaxation to ACh is impaired in LDLR(-/-) mice. Reduced biosynthesis or increased inactivation of H(2)O(2) is the possible mechanism responsible for endothelial dysfunction in aortas of atherosclerosis-susceptible LDLR(-/-) mice.     

Improvement in regional myocardial O2 supply and O2 consumption by nitroglycerin during ischemia

In eight open-chest anesthetized dogs, nitroglycerin (10 micrograms/kg per min) was infused intravenously for 2 h, beginning 10 min following ligation of the left anterior descending coronary artery. Oxygen supply, (radioactive microspheres), extraction (microspectrophotometry) and consumption were determined in subepicardial and subendocardial regions of both ischemic and non-ischemic myocardium, and compared to eight control hearts. In control, coronary occlusion reduced both subepicardial and subendocardial blood flow by 49.5% and 79.5% respectively. In the presence of nitroglycerin, depression of blood flow to the occluded regions was significantly less marked (-79.5% in control and -26.6% in the nitroglycerin group in the subendocardium). O2 extraction was significantly lowered by nitroglycerin in all areas. Regional O2 consumption was significantly lower in the control occluded than non-occluded regions; no regional O2 consumption differences were observed following nitroglycerin. In the occluded regions, nitroglycerin reduced the number of veins with very low O2 saturation. It is concluded that nitroglycerin improves the O2 supply/consumption balance in ischemia by redistribution of blood flow and possibly by alterations in local O2 consumption.     

Effects of nitroglycerin on regional O2 supply and O2 consumption in reperfused dog myocardium

This study was designed to assess whether nitroglycerin would improve the relationship between O2 supply and O2 consumption in the reperfused ischemic dog myocardium. In 16 dogs the left anterior descending coronary artery was occluded for 2 h, followed by a 4 h period of reperfusion. In 8 of the 16 dogs, an infusion of 10 micrograms/kg per min of nitroglycerin was begun 10 min prior and continued during 4 h of reperfusion. Small artery and vein O2 saturations obtained microspectrophotometrically were combined with regional blood flow measurements using radioactive microspheres to determine regional myocardial O2 consumption. In both groups, 2 h of occlusion lowered the regional flow to a similar level. In the control group, 4 h of reperfusion returned the blood flow towards normal levels, from 15 +/- 20 ml/min per 100 g (mean +/- S.D.) at the end of occlusion to 57 +/- 39 in the affected area compared to 84 +/- 32 ml/min per 100 g in the nonischemic area. In nitroglycerin treated animals, the flow increase with reperfusion was similar to the control group (12 +/- 10 to 65 +/- 33 ml/min per 100 g). O2 extraction was greater in the reperfused than in the unaffected area in both groups. However, reperfused region O2 extraction was lower in the nitroglycerin treated than control group. There was a greater number of arteries and veins with reduced O2 saturations in the control group reperfused area compared to the nonischemic area. Nitroglycerin decreased the number of low O2 saturation vessels in the reperfusion area. Reperfusion alone does not restore the ratio of O2 supply to O2 consumption to control values, while nitroglycerin significantly improves this ratio. Thus nitroglycerin appears to better match the increased flow during reperfusion with microregional O2 consumption.     

过氧化氢熏蒸消毒手术物品的效果观察

本文报道使用过氧化氢熏蒸消毒法用于手术物品的消毒效果。选择电刀导线、尿管、剪刀及橡胶管作为试验对象,将以上物品放于自制的消毒箱内,将过氧化氢加热挥发,封闭消毒箱2h,以上物品消毒前后分别在无菌技术下用同样的方法采集标本,进行细菌培养。结果：消毒后全部无细菌生长,合格率达100%。文章认为,过氧化氢主要是由于加热后挥发释放出新生态氧,破坏细菌酶的结构,致使细菌代谢发生障碍,从而起到杀菌消毒作用。     

Vibrio cholerae O2 as a cause of a skin lesion in a tourist returning from Tunisia

Isolates of Vibrio cholerae other than O1 and O139 (non O1 Vibrio cholerae) are associated with sporadic diarrheal disorders, and limited outbreaks of diarrhea, and have often been reported in association with extraintestinal infections. The majority of cases of non O1 Vibrio cholerae infection involve immunocompromised patients with hematologic malignancies or cirrhosis. In Italy, very few cases of gastrointestinal and extraintestinal infections due to non O1 Vibrio cholerae have been described in the past years. We describe a case of non O1 Vibrio cholerae infection with cutaneous bullous lesions in a tourist returning from Tunisia.     

Beta-glucuronidase-cleavable prodrugs of O6-benzylguanine and O6-benzyl-2'-deoxyguanosine

Glucuronic acid linked prodrugs of O(6)-benzylguanine and O(6)-benzyl-2'-deoxyguanosine were synthesized. The prodrugs were found to be quite stable at physiological pH and were more than 200-fold less active as inactivators of O(6)-alkylguanine-DNA alkyltransferase (alkyltransferase) than either O(6)-benzylguanine or O(6)-benzyl-2'-deoxyguanosine. Beta-glucuronidase from both Escherichia coli and bovine liver cleaved the prodrugs efficiently to release O(6)-benzylguanine and O(6)-benzyl-2'-deoxyguanosine, respectively. In combination with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), the prodrugs were not effective adjuvants for HT29 cell killing. However, as expected, incubation of these prodrugs with beta-glucuronidase in the culture medium led to much more efficient cell killing by BCNU as a result of the liberation of the more potent inactivators, O(6)-benzylguanine and O(6)-benzyl-2'-deoxyguanosine. These prodrugs may be useful for prodrug monotherapy of necrotic tumors that liberate beta-glucuronidase or for antibody-directed enzyme prodrug therapy with antibodies that can deliver beta-glucuronidase to target tumor cells.     

Alpha-lipoic acid, a scavenging agent for H2O2, reduces ethanol-stimulated locomotion in mice

Rationale  

The main system of central ethanol oxidation is mediated by the enzyme catalase. By reacting with H₂O₂, brain catalase forms compound I (the catalase–H₂O₂ system), which is able to oxidize ethanol to acetaldehyde in the brain. Previous studies have demonstrated that pharmacological manipulations of brain catalase activity modulate the stimulant effects of ethanol in mice. However, the role of H₂O₂ in the behavioral effects of ethanol has not yet been clearly addressed.     

Development and quantification of H2O2 decontamination cycles

Whereas correlation of physical process parameters with bacterial reduction is well established in thermal sterilisation, such a method is currently neither generally recognised nor possible for H2O2 decontamination. As a result, the efficiency and reproducibility of H2O2 decontamination and the course of the process over time can at present only be ascertained, verified, and documented using a microbiological system. Based on the "Fractional Negative" method of determining the D-values of Biological Indicators (BIs), which is contained in the ISO 11138-1 and EN 866-3 standards, a complete and systematic method is presented that enables the parameters for each cycle phase to be determined and verified, and the effectiveness of the process to be quantified. The method also enables differences in bacterial reduction between positions which can be effectively decontaminated and "worst case" positions to be quantified, so that, using the results, the process can be individually adjusted to specific overall bacterial reduction requirements. The new method also specifies the procedure for assessing the suitability of the microbiological system used prior to qualification and validation a condition sine qua non if process parameter studies are to be used to establish and document a decontamination cycle. With the aid of practical experimental data, this paper presents in detail the individual stages involved in the method proposed for decontamination cycle development, and interpretation of the results and their implications for the process parameters. In particular, it is shown that bacterial reduction is only stable over time under certain conditions, and that doubling the decontamination time does not result in doubling of kill effect. Moreover, the method makes it possible to react to any fluctuations in resistance in the microbiological system employed, which occur during requalification of the process.     

潘生丁抑制中性粒细胞过氧化氢的产生机制

中性粒细胞是循环系统中最丰富的白细胞,并且是最先到达感染或者发炎部位的细胞。被激活的中性粒细胞可吞噬细菌、细菌碎片、细菌有氧代谢产物和溶酶体,研究表明[1],中性粒细胞在组织缺血再灌注损伤过程中,起着重要的作用。因此,药物可通过干扰中性粒细胞的作用,对组织细胞起到     

Green tea catechins evoke a phasic contraction in rat aorta via H2O2-mediated multiple-signalling pathways

1. The contractile effects of tea polyphenols (TP) and its four principle catechins, namely (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), on rat aorta contractility were investigated using the isometric tension recording technique. 2. At concentrations of 5-100 mg/L, TP evoked phasic contraction of rat aorta in a concentration-dependent but endothelium-independent manner. Of the four catechins tested, EGCG and EGC (3-300 micromol/L), but not EC and ECG, mimicked the contractile response to TP, suggesting that the epigallol moiety in the B ring may be associated with the contractile effect. 3. Contractions in response to EGCG and EGC were not affected by several endogenous vasoconstrictor receptor antagonists, but could be abolished by 10 micro mol/L BAPTA-AM, a membrane-permeable Ca2+ chelator, or attenuated by removal of extracellular Ca2+, suggesting the involvement of both intracellular and extracellular Ca2+ in evoking the contraction. 4. Pretreatment with non-selective Ca2+ channel antagonists mefenamic acid (10 micro mol/L), tetrandrine (30 micro mol/L) and SKF 96365 (30 micromol/L), but not nifedipine (1 micromol/L), the selective inhibitor of voltage-dependent Ca2+ channels, inhibited the contractile responses to EGC and EGCG, indicating the involvement of Ca2+ influx via non-voltage dependent Ca2+ channels. 5. Several intracellular Ca2+ channel modulators, including procaine (5 mmol/L), dantrolene (30 micromol/L) and 2-amino ethoxydiphenyl borate (50 micromol/L; an inositol 1,4,5-trisphosphate receptor inhibitor), also inhibited EGCG- and EGC-induced contractions, thus suggesting a role of intracellular Ca2+ release in these contractions. 6. Both EGCG- and EGC-induced contractions were depressed, to different degrees, by inhibitors of several receptor-coupled enzymes, including phospholipase C, protein kinase C, phospholipase A2 and tyrosine kinase. Furthermore, both EGCG- and EGC-induced contractions were completely abolished by catalase, but not by superoxide dismutase or mannitol/dimethyl sulphoxide. 7. Taken together, these data show, for the first time, that TP and its related catechins that contain an epigallol structure in the B ring, as in EGCG and EGC, exert direct contractile effects on rat aortic smooth muscle via a H2O2-mediated pathway.     

Quantitation of the Relative Amounts of Anhydrous Carbamazepine (C15H12N2O) and Carbamazepine Dihydrate (C15H12N2O · 2H2O) in a Mixture by Solid-State Nuclear Magnetic Resonance (NMR)

The application of solid state nuclear magnetic resonance (NMR) for the quantitation of the relative amounts of carbamazepine anhydrate (I) and Carbamazepine dihydrate (II) in a mixture is presented. The techniques of cross polarization, dipolar decoupling, and magic angle spinning have been used to obtain high-resolution NMR spectra of the samples in the solid state. Although the chemical shifts of I and II were similar, the proton spin lattice relaxation time of II was much shorter than that of I. A delay time of 10 sec between pulses resulted in saturation of the signal from I and in a spectrum arising solely from II. The dependence of the observed signal intensity on the contact time was evaluated for II and glycine, the internal standard, to allow theoretical estimation of the peak area ratios. Various molar ratios of I and II were then mixed with glycine, and the resulting peak area ratios of II to the area of the alpha and the carbonyl carbons of glycine was linearly related to the relative proportion of II in the mixture.     

Penicillin-enhanced chemiluminescence of the luminol-H2O2-Co2+ system.

The luminol-H2O2-Co2+ system has been widely used in chemical and biological analysis. We report here an investigation of the observation that penicillins have the ability to prolong and enhance the intensity of chemiluminescence from luminol. The basis of this phenomenon appears, as revealed by difference spectroscopy, to be the formation of a complex between the beta-lactam and the superoxide ion. The latter is the oxidizing species responsible for the oxidation of luminol in alkaline solution and has a mean lifetime, in solution, of milliseconds. The stabilization of the superoxide ion by penicillin complexation extends the effective lifetime of the superoxide ion by a few orders of magnitude and thereby allows for more efficient oxidation of the beta-lactam. Several penicillins were determined by their enhancement of luminol chemiluminescence. A detection limit of 100 ng mL was obtained for penicillin G with a less-than-ideal detection system.     

Synergism in insulin-like effects of molybdate plus H2O2 or tungstate plus H2O2 on glucose transport by isolated rat adipocytes.

The effect of molybdate, tungstate, molybdate plus H2O2 or tungstate plus H2O2 on 3-O-methylglucose (3-O-MG) uptake was studied in isolated rat adipocytes to investigate whether these agents possess an insulin-like action. High concentrations (10-30 mM) of molybdate or tungstate significantly stimulated the uptake of 3-O-MG while 1 mM of the metaloxides did not. The combination of 1 mM molybdate and 1 mM H2O2, or 1 mM tungstate and 1 mM H2O2 induced striking stimulation of the uptake of 3-O-MG in a synergistic manner, whereas 1 mM H2O2 alone showed only a small effect. The effect of metaloxides plus H2O2 (1 mM) and the effect of insulin (20 nM) were not additive, and both effects were ATP or energy dependent based on experiments using KCN. These results indicate that a weak insulin-like effect of molybdate or tungstate is potentiated synergistically with H2O2, presumably by producing peroxocompounds. Based on the present findings, these new agents may be useful for investigating the mechanism of insulin action and may indicate a new class of drugs for diabetes mellitus.     

下调microRNA-1对H2O2诱导的心肌细胞损伤的保护作用

【摘要】目的? ?研究下调microRNA-1在H2O2诱导的心肌细胞损伤中的保护作用及其机制。方法? ?将大鼠H9c2心肌细胞株分为4组,Blank组、NC组、H2O2组和H2O2+AS-miR-1组。Blank组为不做任何处理的空白对照组,NC组细胞转染随机合成的miRNA阴性对照片;H2O2组和H2O2+AS-miR-1组分别为不转染或转染miR-1 inhibitor（AS-miR-1）的H2O2细胞损伤组。采用定量PCR方法检测各组miR-1表达水平,MTT和流式细胞术检测细胞存活率和凋亡情况,利用生物信息学预测miR-1的靶基因,荧光定量PCR和Western Blot的方法检测靶基因Bcl-2的mRNA和蛋白表达情况。结果? ?Blank组和NC组相比较,各个指标均没有统计学差异。H2O2组细胞的miR-1mRNA表达水平显著升高,存活率降低,凋亡增加,Bcl-2的mRNA和蛋白表达水平均明显降低。转染AS-miR-1,可以降低H2O2诱导的心肌细胞损伤,提高细胞存活率、降低细胞凋亡,上升Bcl-2的mRNA和蛋白表达水平。 结论? ?下调miR-1表达可以通过升高凋亡抑制因子Bcl-2的表达水平降低H2O2诱导的心肌细胞凋亡,发挥心肌细胞保护作用。