绿茶对胃癌癌前高危因素及癌细胞增殖的干预作用研究

采用体外实验及动物实验方法，研究绿茶在正常饮用浓度下对胃癌几种高危因素的干预作用及对胃癌细胞增殖的抑制作用。结果表明：绿茶水能有效消除ＮａＮＯ２，消除率与茶剂量对数呈显著正相关；１％绿茶水对鱼露亚硝酸钠饮水诱导大鼠ＬＰＯ增高有明显阻抑作用；１％绿茶水对鱼露亚硝酸钠饮水诱导的胃粘膜增生肥厚有一定遏制保护作用；１％绿茶水对酒精引起的胃粘膜出血性损伤有明显减轻作用；５％绿茶水再稀释２０～２００倍时对胃癌细胞系ＦＧＣ－８５细胞株的增殖均有抑制作用，抑制率随茶浓度增加而升高，呈现剂量－效应关系。     

食品加工与亚硝酸盐生成的关系

本文以经典方法测定了几种肉、蛋、菜加工制品及其同种属新鲜品中的亚硝酸盐含量，结果表明一般加工制品中的NO含量高于同种鲜品几倍至几十倍。同时发现NO含量与贮存时间及环境温度呈正相关。     

1起食源性亚硝酸盐中毒事件调查分析

目的通过此次食源性亚硝酸盐中毒事件的调查,分析事件中毒原因,总结应对中毒事件经验,为预防类似食源性疾病事件发生提供依据。方法收集患者食源性疾病事件个案调查表,对可疑餐次开展现场流行病学调查、食品卫生学调查、结合临床表现和实验室检测对事件进行综合分析。结果发病者一家共3人,其中有2人进餐食品相同,发病2例,潜伏期30~60 min,临床表现以紫绀、恶心、腹泻、头昏不适、乏力为主,经特效药亚甲蓝治疗后症状迅速缓解。剩余卤鸡腿、卤鸡腿汤中检出亚硝酸盐含量超标。认定为1起食源性亚硝酸盐中毒事件。结论该事件由于误食亚硝酸盐引起,应加大食品安全宣传力度,提高居民自我保护意识;哨点医院要强化监测预警,及时发现、及时报告、及时救治;相关部门要加强食品添加剂尤其是亚硝酸盐的市场监管,预防类似事件发生。     

Bioavailability of sodium nitrite from an aqueous solution in healthy adults

Nitrate intake in humans is high through intake of vegetables such as beets, lettuce, and spinach. Nitrate itself is a compound of low toxicity but its metabolite, nitrite, formed by bacteria in the oral cavity and gastrointestinal tract, has been suspected of potential carcinogenic effects. Nitrite can induce systemic toxicity only after having been absorbed from the gastrointestinal tract. The aim of this study was to determine the absolute bioavailability of nitrite following oral administration in humans. In an open, three-way cross-over study, nine subjects received two single oral doses of sodium nitrite (0.12 and 0.06 mmol NaNO₂/mmol Hb) and one intravenous sodium nitrite dose (0.12 mmol NaNO₂/mmol Hb). Plasma samples were analysed to assess the nitrite levels, and pharmacokinetic parameters were calculated. Nitrate and methaemoglobin levels in plasma were also measured as oxidation of nitrite results in the formation of these two compounds. Absolute bioavailability of nitrite was 98% after oral administration of 0.12 mmol NaNO₂/mmol Hb, and 95% after oral administration of 0.06 mmol NaNO₂/mmol Hb. Minor adverse effects were observed after the 0.12 mmol NaNO₂/mmol Hb oral dose. In conclusion, nitrite in solution is highly absorbed from the gastrointestinal tract and the first pass effect in the liver is low.     

一起亚硝酸盐食物中毒的调查

目的通过一起亚硝酸盐食物中毒的调查检测及分析,总结经验,为制定防治方法提供依据。方法用盐酸萘乙二胺法检测样品中的亚硝酸盐。结果在患者的洗胃液及呕吐物中均检出亚硝酸盐。结论食物中毒为变质食物引起的亚硝酸盐中毒。     

Nitrite content and antioxidant enzyme levels in the blood of schizophrenia patients

RATIONALE: Recent studies have suggested augmentation in the inflammatory response as well as involvement of nitric oxide (NO) in mood disorders. Polymorphonuclear leukocytes (PMN), NO and free radicals have been associated with inflammatory response; however, the status of NO in the PMN has not been investigated so far in schizophrenia patients. OBJECTIVES: The present study was undertaken to investigate levels of nitrite (a metabolite of NO), malonaldehyde (MDA, lipid peroxidation product) and antioxidant enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase (Gpx) in the PMN of schizophrenia patients. METHODS: Patients with schizophrenia (n=62) were diagnosed according to DSM-IV and were free of anti-psychotic medications/ECT for at least 3 months. Mean age of the patients was 29.06+/-1.17 years, with a male to female ratio of 4:1, and mean duration of illness was 3.7+/-0.6 years. The control group consisted of 82 healthy subjects with a mean age of 37.0+/-1.26 and a male to female ratio of 5:1. PMN were isolated from the blood. Nitrite, MDA and antioxidant enzymes were estimated by standard biochemical techniques in the PMN of normal healthy controls and schizophrenia patients. Platelet and plasma nitrite levels were also estimated in controls and schizophrenia patients. RESULTS: Nitrite content in the PMN was reduced to 68%, while plasma and platelet nitrite content in schizophrenia patients was not significantly changed in comparison to controls. Malonaldehyde (MDA) content in PMN was significantly augmented in schizophrenia patients but activity of SOD, catalase and Gpx remain unaltered. CONCLUSION: Results obtained indicate a significant decrease in NO synthesis and an increase in MDA in the PMN of schizophrenia patients, while antioxidant enzyme activities were not altered in the PMN of schizophrenia patients. This suggests that the decrease in PMN NO synthesis by PMN might lead to oxidative stress in schizophrenia patients.     

群体性亚硝酸盐中毒的急救与护理

总结了14例群体性亚硝酸盐中毒的急救与护理措施。包括严密管理、合理分工,及早、彻底地清除毒物,保持呼吸道通畅,抗休克护理等。认为在群体性亚硝酸盐中毒患者救治中,正规化、科学化、程序化的护理管理模式以及积极的急救护理措施可明显提高急救质量和效率。     

Effect of Chronic Ethanol Feeding on Nitric Oxide Synthesis by Rat Kupffer Cells

Kupffer cells contribute to the important role of the liver defense mechanism through nitric oxide (NO) production. In this study, the effect of chronic ethanol administration on the ability of Kupffer cells to synthesize and release NO was investigated after stimulation with lipopolysaccharide (LPS). Male Wistar rats were chronically fed ethanol for 8 weeks according to the method described by DeCarli and Lieber et al. ( J Nutr. 91:331–336, 1967). Kupffer cells were isolated and cultured with LPS (1 μg/ml) for 24 hr. The levels of nitrite and nitrate, metabolites of NO, were determined in the culture medium. NO synthase (NOS) activity in Kupffer cells was determined by the method that measures conversion of [¹⁴C]arginine into [¹⁴C]citrul-line. In control rats, a significant increase of nitrite and nitrate levels in culture medium was observed after LPS treatment. The magnitude of this increase was significantly smaller in chronic ethanol-fed rats. When the activity of NOS was determined, inducible NOS (iNOS) activity was higher than that of constitutive NOS, and LPS administration produced a significant elevation of iNOS activity in both control and chronic ethanol-fed rats. However, the elevation of iNOS activity by LPS stimulation was diminished by chronic ethanol administration. Distribution of iNOS in Kupffer cells as determined by an immunofluorescence method using a laser scanning confocal image system showed a lower expression of iNOS in chronic ethanol-fed rats even in the presence of LPS. These results demonstrate that the excessive production of NO by increased iNOS activity in Kupffer cells is diminished by chronic ethanol administration.     

Reduction of nitrite on tin-modified noble metal electrodes

The electrocatalytic activity and product distribution of the nitrite reduction on Sn-modified noble metal (Ru, Pd, Rh, Pt, and Ir) electrodes, as well as unmodified noble metal electrodes, were examined in a 0.1 M HClO₄ solution. The most effective coverages were 0.35 and 0.55 for the Sn/Pt and Sn/Pd, respectively. The activity of the Sn/Ru, Sn/Rh, and Sn/Ir electrodes simply increased with an increase in the Sn coverage. From the maximum current densities at −0.1 V, the orders of the reduction activity for the unmodified and Sn-modified electrodes were Ir > Pt > Pd > Ru > Rh and Sn/Ir ≈ Sn/Ru > Sn/Rh ≈ Sn/Pt > Sn/Pd, respectively. The electrolysis of nitrite for 5 h was carried out on each electrode in 0.1 M HClO₄ at −0.2 V. The conversion of nitrite increased due to the Sn modification (4–27% conversion). The highest N₂ selectivity (53%) was obtained using the unmodified Pt electrode. Sn was not effective for the N₂ selectivity.     

Classification of Groundwater Contamination in Yuxi River Valley,Shaanxi Province,China

This study investigated groundwater contamination in the Yuxi River Valley in northern Shaanxi Province, one of largest energy resource centers in China. Groundwater samples collected from 129 locations in the Yuxi River Valley area were analyzed and evaluated to establish the local groundwater quality zonings. Results indicate that groundwater in the Yuxi River Valley is contaminated, and the dominant contaminants in the groundwater are ammonium (NH₄ ⁺) and nitrite (NO₂ ⁻). Maximal concentration of NH₄ ⁺ was detected at 0.019 and 3.50 mg/L in the samples collected up-gradient and down-gradient, respectively, of the segment of Yuxi River that flows through Yulin City. Concentration of NO₂ ⁻ was detected at 0.0015 and 1.522 mg/L, respectively from the same samples. Zones I through IV, from non-polluted to seriously polluted, were identified for groundwater quality in the Yuxi River Valley. We attribute the groundwater contamination in the Yuxi River valley to sources in the Yulin township, presumably its wastewater discharge.