小鼠大脑亚硝酸盐暴露与DNA甲基化和组蛋白去乙酰化

目的 观察慢性亚硝酸盐暴露对小鼠大脑皮质炎症损伤的影响及其探讨DNA甲基化和组蛋白去乙酰化等相关机制。方法 选取8周龄健康雄性C57BL/6J小鼠,随机分为对照组（生理盐水）、低剂量亚硝酸盐组（3g/L）和高剂量亚硝酸盐组(6g/L),建立亚硝酸盐暴露模型,收集各组小鼠大脑皮质,利用免疫荧光染色法和Western blotting法分析大脑皮质炎症损伤,组蛋白去乙酰化酶和DNA甲基化相关酶的表达情况。结果 慢性亚硝酸盐暴露后小鼠大脑皮质炎症损伤因子环氧化酶2（COX2）、白细胞介素-1β（IL-1β）、离子钙接头蛋白分子1（Iba1）、c-Fos、IL-6表达量明显多于对照组（P<0.01）,同时高剂量暴露组DNA甲基化相关酶5-甲基胞嘧啶（5-mC）、DNA甲基转移酶1(DNMT1)、DNMT3a、和组蛋白去乙酰化酶1（HDAC1）表达明显低于对照组（P<0.01）且都呈亚硝酸盐剂量依赖性。结论 亚硝酸盐暴露可通过促进细胞免疫炎症对小鼠大脑皮质造成损伤,并且DNA甲基化和组蛋白去乙酰化可能参与了慢性亚硝酸盐暴露过程中的应答过程及其调控机制。     

局部冷冻对血管及机体合成一氧化氮的影响

目的:本实验通过对在体家兔动脉及心脏局部冷冻,观察冷冻对血管合成一氧化氮功能的影响,以及机体对冷冻的全身性反应的有关征象。方法:以家兔作为实验对象,随机分成对照组和冷冻组,以Ignarro和Green法测定血管壁的NO_2~-含量,以Shechter法测定NO_2~-浓度,在实验中分别测定冷冻前后血管壁和血液中心NO_2~-浓度。结果:①主动脉及股动脉壁冷冻10秒复温后随时间的延长动脉管壁NO_2~-含量逐渐升高。②对主动脉管壁冷冻2分钟后可见主动脉管壁NO_2~-含量明显下降。③对主动脉壁冷冻10秒钟后,血液中的NO_2~-含量未见明显变化。①对心脏心外膜冷冻10秒钟后血液中NO_2~-含量未见明显变化。结论:血管壁的冷冻对血管合成一氧化氮(NO)的功能影响较大,当冷冻时间较短时,血管壁合成NO的量随时间延长而增多。但是,随首冷冻时间增加,血管壁合成NO的量减少,由此可造成不良的后果。     

一种新的水中亚硝酸盐点滴检验法

目的介绍一种水中亚硝酸盐快速点滴检验法,以适应污染事故应急监测亚硝酸盐的需要.方法根据欧洲饮水法规亚硝酸盐限值(0.10 mg/L),使用一种优化的试剂混合物和二元的阳性-阴性反应,建立一种水中亚硝酸盐快速点滴检验法.结果将1片含磺胺、N-(1-萘)乙二胺二盐酸盐和氯化钠的固体试剂混合物放在聚四氟乙烯模的点滴检验板上.加1滴30%(体积分数)盐酸和1滴水样于试剂片上.在此情况下,所有含NO-2≥0.10 mg/L的检验水样均产生紫红色阳性反应,而给出阴性反应(无色)的水样表明NO2-含量低于此限值.实际水样均显示明确的阴性或阳性反应,且均由光度法根据相同的试剂测定得到确认.结论该方法简易、快速和准确,适合现场水中亚硝酸盐的监测.     

离子色谱法测定蔬菜中硝酸盐和亚硝酸盐

目的探讨离子色谱测定蔬菜中硝酸盐和亚硝酸盐。方法对离子色谱测定蔬菜中硝酸盐和亚硝酸盐的条件进行优化,同时进行方法学对照及实际样品测定。结果NO-2其变异系数为2.5%,加标回收率为99%～103%;NO-3其变异系数为1.1%,加标回收率为98%～102%,对照实验t相似文献   

Fluorometric assay of nitrite and nitrate in brain tissue after traumatic brain injury and cerebral ischemia

Nitric oxide synthase (NOS) is distributed within the brain, and nitric oxide (NO) is felt to be involved in the pathophysiology of deterioration after head injury and cerebral ischemia. This study determined the levels of the stable end products of NOS (NO_x=nitrite+nitrate) after traumatic brain injury (TBI) and transient cerebral ischemia. A fluorometric assay using nitrate reductase and the NADPH regenerating system was used to quantitate NO_x in ultrafiltered (10-kDa cutoff) cortical and hippocampal extracts after reduction of nitrate. In TBI rats, both the plasma and tissue showed a sharp increase in NO_x levels 5 min after injury. Plasma NO_x returned to control levels by 2 h after injury. Ipsilateral-cortex NO_x levels returned to control levels 6 h after injury and remained constant from 6–24 h. Contralateral-cortex returned near to control levels after 1 h. Hippocampus also followed a similar trend. In gerbils, there was a significant elevation in tissue NO_x levels immediately after 10 min transient cerebral ischemia, which gradually returned to control levels over 24 h reperfusion. This striking burst of NO synthesis immediately after injury is clearly evident whether the injury is head trauma or ischemia, or whether the measurements were performed on tissue or plasma. It is unknown whether endothelial NOS, neuronal NOS, or both caused the elevation of the NO end products seen after the CNS insults.     

Combined effects of carbon monoxide plus sodium nitrite or carbon tetrachloride on the sciatic motor conduction velocity of rats

Summary Combined administrations of 0.2 or 0.4 mmol sodium nitrite/kg i.p. and 1.2 mmol carbon monoxide/kg s.c., or administration of 1.2 mmol carbon monoxide/kg alone decrease the sciatic motor conduction velocity of rats to the same degree. Pretreatment of rats with 8.3 mmol carbon tetrachloride/kg per os did not influence the retardation of the nerve conduction following carbon monoxide intoxication. The results support the assumption that the carbon monoxide poisoning lead to threshold values of motor conduction velocity; the additional toxic substances examined are not able to aggravate this effect.     

Potential health effects of chlorine dioxide as a disinfectant in potable water supplies

Chlorination of potable water supplies high in organics may yield carcin-ogenic compounds such as trihalomethanes. Chlorine dioxide has been proposed as an alternative disinfectant to chlorine. However, chlorine dioxide is a strong oxidant that forms significant amounts of chlorite when added to potable water supplies, and chlorite is similar to nitrite in its molecular structure and may be similar in its mechanism of methemoglobin production. Nitrites and chlorites are thought to act synergistically to produce MetHb. Neonates and persons with G-6-PD deficiency are likely to be unusually susceptible to MetHb formation from these compounds because their red cells lack the metabolic machinery to adequately protect against oxidant stress. Since male blacks represent the largest population in the U.S. to be G-6-PD deficient, Black male neonates may represent the group at highest risk to the use of chlorine dioxide as a disinfectant in the nations water supplies.     

Mutagenicity Arising from Boiled Rice on Treatment with Nitrous Acid

When an aqueous homogenate of boiled rice was treated with nitrous acid at pH 3, direct-acting mutagens were formed. The presence of the mutagens was demonstrated by isolating the mutagenic fractions through blue-rayon adsorption, a method used to extract polycyclic compounds, and subsequent high-performance liquid chromatography (HPLC). The mutagens were active in Salmonella typhimurium TA100 and TA98 without metabolic activation. Several different mutagens were formed, as judged from the HPLC profile.     

溴酸钾氧化茜素红催比色测定肉制品亚硝酸盐含量

在酸性条件下,通过溴酸钾氧化茜素红可测定反应催化剂亚硝酸盐含量,其最大吸收峰为4151nm;,在15～70μg亚硝酸盐范围内线性相关(r=0.9996),回收率89.1％～98.7％。     

Investigation of the electrochemical behavior of metallo-tetraazaporphyrin modified silver and pyrolytic graphite electrodes in aqueous nitrite solution

Five new complexes of the type [M(OBTTAP)] (where M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺; OBTTAP = 2,3,7,8,12,13,17,18-octakis(benzylthio)-5,10,15,20-tetraazaporphyrin(2?)) were used to prepare modified silver and pyrolytic graphite electrodes and their electrochemical behavior towards the reduction of aqueous nitrite solution was investigated in acidic, neutral and alkaline medium. Of these electrodes, [Co(OBTTAP)] and [Cu(OBTTAP)] modified electrodes showed affinity for ${\mathrm{NO}}_2^{-}$ ions and thereby exhibited significantly altered cathodic responses. The [Co(OBTTAP)]/Ag electrode in acidic, neutral and also in alkaline nitrite solutions, exhibited a new one electron irreversible reduction wave at E_p,c ～ ?0.2 V vs. Ag|AgCl. The [Cu(OBTTAP)]/Ag electrode in acidic and neutral nitrite solutions also behaved in a similar manner. However, in alkaline aqueous nitrite solution it showed two successive one electron reductions, the first reversible reduction at E_1/2 = ?0.26 V and the second irreversible reduction at E_p,c = ?0.73 V vs. Ag|AgCl. Controlled potential electrolysis of alkaline nitrite solutions using a [Cu(OBTTAP)]/Ag cathode led to isolation of a nitrosyl complex. The peak current, particularly with [Cu(OBTTAP)]/Ag microelectrode in alkaline medium, showed a linear response to $[{\mathrm{NO}}_2^{-}]$ and could be exploited in the electrochemical sensing and determination of ${\mathrm{NO}}_2^{-}$.