The evaluation of effects of lipoic acid on the lipid peroxidation,nitrite formation and antioxidant enzymes in the hippocampus of rats after pilocarpine-induced seizures

It has been suggested that pilocarpine-induced seizures is mediated by increases in oxidative stress. Current researches have suggested that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures in cellular level. The objective of the present study was to evaluate the neuroprotective effects of lipoic acid (LA) in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), LA (10 mg/kg, i.p., LA group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of LA (10 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before of administration of LA (LA plus pilocarpine group). After the treatments all groups were observed for 6 h. The enzyme activities as well as the lipid peroxidation and nitrite concentrations were measured using spectrophotometric methods and the results compared to values obtained from saline and pilocarpine-treated animals. Protective effects of LA were also evaluated on the same parameters. In pilocarpine group there was a significant increase in lipid peroxidation and nitrite level. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content as well as increased the superoxide dismutase and catalase activities in hippocampus of rats after seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that strong protective effect could be achieved using lipoic acid as an antioxidant.     

深圳市腌腊制品中亚硝酸盐含量的调查

目的了解深圳市市场上腌腊制品中亚硝酸盐污染状况,为相关部门提供监管依据。方法采用国家食品卫生检验标准方法（GB／T5009133—2003）即食品中亚硝酸盐与硝酸盐的盐酸萘乙二胺比色法对市场上抽检108份腌腊制品中亚硝酸盐含量进行测定,对测定结果进行分析。结果亚硝酸盐超标率为22．2％,其中腊猪耳、腊兔、麻辣肠、腊鸡和猪头肉类亚硝酸盐平均含量分别高达71．0、56．7、46．2、37．6和35．9mg／kg。不同类样品（腊家禽、腊兔、腊猪肉及内脏、腊牛肉、腊兔肉）的亚硝酸盐含量和超标率差别有统计学意义（χ^2=102．79,P〈0．01）。结论市售腌腊制品中亚硝酸盐滥用情况比较普遍,应引起有关部门重视。     

分光光度法测定酱腌菜类食品中亚硝酸盐的实验室质量控制

目的:探讨测定酱腌菜类食品中亚硝酸盐含量的盐酸萘乙二胺分光光度法的实验室质量控制。方法:对贵阳市两城区市售的5类40种酱腌菜类食品中亚硝酸盐暴露水平进行抽样,检测方法采用盐酸萘乙二胺分光光度法测定,用样品配制成亚硝酸盐加标浓度为4.0 mg/kg的实验室内部质控样,每天平行测定1次,连续20 d,计算各次加标回收率、均值及标准差,制作准确度控制图。结果:回收率算术均值为99.8%,标准差4.32%,则上、下控制限分别为101.5%、98.1%,上、下警告限分别为:101.0%、98.6%,上、下辅助限分别为:100.4%、99.2%,20次质控样测定的回收率在98.8%~100.7%之间,有60%(12/20)的点在辅助线内,无连续7个点位于中心线的同一侧;无连续3个点位于控制限和警告限之间。40种酱腌菜类食品中亚硝酸盐浓度范围为0.08~31.23 mg/kg,亚硝酸盐检出率为57.5%,超标率为8.0%。结论:该研究采用质控方法将盐酸萘乙二胺分光光度法测定酱腌菜类食品中亚硝酸盐的结果控制在规定的误差范围内。     

Characterisation of the nitrite reductase gene (NII1) and the nitrate-assimilation gene cluster of Stagonospora (Septoria) nodorum

By sequencing downstream of the cloned nitrate reductase gene (NIA1) in the phytopathogenic fungus Stagonospora (Septoria) nodorum, a second open reading frame was found. Further analysis revealed this to be the nitrite reductase gene (NII1). Both genes are transcribed in the same direction, and are separated by an intergenic region of 829-bp. The coding sequence of NII1 is interrupted by three small introns and corresponds to a predicted protein of 1141 amino acids in length. Consensus binding sites for regulatory proteins are present in the promoter region of NII1. There is no indication, however, from hybridisation or sequence analysis that the nitrate transporter gene is closely associated with the NIA1-NII1 cluster, as has been found for a number of fungi. Received: 23 November 1998 / 26 April 1999     

大蒜阻断细菌对亚硝胺合成的促进作用

通过实验观察到大蒜提取液可阻断大肠杆菌、肠球菌对二乙基亚硝胺、二丁基亚硝胺合成的促进作用,并有阻断大肠杆菌使硝酸盐还原为亚硝酸盐的作用。     

空气中亚硝酸盐和硝酸盐的离子色谱测定方法的研究

目的:建立空气中亚硝酸盐和硝酸盐的离子色谱测定方法。方法:本文采用超细玻璃纤维滤纸采集空气中亚硝酸盐和硝酸盐,用蒸馏水洗脱过滤后,经色谱柱分离,电导检测器检测,保留时间定性,峰高或峰面积定量。结果:空气中亚硝酸盐和硝酸盐的线性范围分别为0.5~30.0μg/m l和0.5~30.0μg/m l;相关系数分别为0.9997和0.9992;方法的最低检出限分别为0.5μg/m l和0.5μg/m l;若采集300 L空气进行测定,则最低检出浓度分别为0.017 mg/m3和0.017 mg/m3;相对标准偏差分别为0.39%~1.03%和0.45%~1.00%;样品洗脱效率分别为100.4%~103.2%和102.3%~106.8%;采样效率分别为94.8%~100.0%和92.7%~94.6%;样品在室温中至少可保存1周。结论:此法灵敏度高,选择性好,干扰少,是同时检测空气中亚硝酸盐和硝酸盐的好方法。     

改进镉柱分光光度法测定奶制品中硝酸盐及亚硝酸盐

目的：建立镉柱还原分光光度法测定奶制品中硝酸盐和亚硝酸盐的方法。方法：采用进口镉粒,用耐酸碱的活塞旋钮滴定管替代镉柱玻璃管,对国家标准方法镉柱法进行改进后,测定奶制品中硝酸盐和亚硝酸盐,结果：测定结果与国标测定方法一致。结论：经改进后的镉柱法测定奶制品中硝酸盐及亚硝酸盐,制备镉柱简单,再生镉粒冲洗简便,还原效率高,方法简单,省时省力,准确快速。     

The antioxidant and cytotoxic activities of Sonchus oleraceus L. extracts

This study investigated in vitro antioxidant activity of Sonchus oleraceus L. by extraction solvent, which were examined by reducing power, hydroxyl radical-scavenging activity(HRSA) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. 70% MeOH extract had the greatest reducing power while EtOH extract had the greatest HRSA. The antioxidant activity of S. oleraceus extracts was concentration dependent and its IC₅₀ values ranged from 47.1 to 210.5 µg/ml and IC₅₀ of 70% MeOH, boiling water and 70% EtOH extracts were 47.1, 52.7 and 56.5 µg/ml, respectively. 70% MeOH extract of S. oleraceus contained the greatest amount of both phenolic and flavonoid contents. The extracts tested had greater nitrite scavenging effects at lower pH conditions. The cytotoxic activity showed that EtOH extract had the best activity against the growth of stomach cancer cell. These results suggest that S. oleraceus extract could be used as a potential source of natural antioxidants.     

Intragastrale Nitrosation — Risikofaktor für die Carcinomentstehung im operierten Magen?

Zusammenfassung Im Hinblick auf die bekannte Carcinomgefährdung des operierten Magens wurde die Konzentration von Nitrit und N-Nitroso-Verbindungen im Nüchternmagensaft bei 44 magenoperierten Patienten untersucht. Alle Patienten waren aufgrund eines Geschwürleidens operiert worden, wobei die Operation im Durchschnitt 2,5 Jahre zurücklag. Als Kontrollgruppe wurden 26 magengesunde Personen gleicher Altersschichtung herangezogen. Die Konzentration von Nitrit und N-Nitroso-Verbindungen im Magensaft unterschied sich bei proximal-gastral vagotomierten Patienten (PGV) nicht von denen der Kontrollgruppe. Dagegen fand sich ein signifikanter Anstieg der Nitrit-Konzentration im Magensaft bei den nach Billroth I oder Billroth II magenresezierten Patienten. Der Anteil von N-Nitroso-Verbindungen war jedoch nur im Billroth-II-resezierten Magen signifikant gegenüber den übrigen untersuchten Magensaftproben erhöht. Auf die mögliche Bedeutung des Anstieges von Nitrit und N-Nitroso-Verbindungen für die Carcinomgefährdung des Restmagens wird hingewiesen.

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Intragastral nitrosation — Cancer risk in the operated stomach

Summary The concentration of nitrite and N-nitroso compounds was examined in the fasting gastric juice of 44 patients with regard to the known cancer risk to the operated stomach. All patients had surgery for therapy of an ulcer disease. The operation had taken place an average of 2.5 years previously. Enlisted as a control group were 26 age-matched individuals with healthy stomachs. The concentration of nitrite and N-nitroso compounds in the gastric juice of the vagotomized patients (PGV) did not differ from that of the controls. On the other hand, a significant increase of the nitrite concentration was found in the gastric juice of those patients resected according to the Billroth I or II procedures. The fraction of N-nitroso compounds, however, was significantly elevated in relation to the other gastric juice samples only in the Billroth II resected stomach. The importance of the increase of nitrite and N-nitroso compounds to the cancer risk inherent in the gastric stump is the subject of discussion.

     

表面活性剂增敏催化共振光散射法测定痕量亚硝酸根

目的：建立测定痕量亚硝酸根的新方法。方法：基于硫酸介质中，亚硝酸根催化溴酸钾氧化健那绿的反应，使其与十二烷基苯磺酸钠缔合的共振光散射强度减弱，据此建立了催化共振光散射分析法测定亚硝酸根的新方法。结果：方法的线性范围为0．83—41．67ng／ml，检出限0．70ng／ml。RSD为1．32％、1．24％，样品加标回收率为96．1％-103．9％。结论：该方法简便快速，常见物质干扰小，用于环境水样痕量的亚硝酸根测定，结果满意。