大理州市市售肉制品中亚硝酸盐含量检测结果分析

目的了解当前大理州市售肉制品中亚硝酸盐含量,为加强食品安全管理监督提供科学依据,并对其潜在危害进行分析。方法选择大理州有代表性的农贸市场及超市采集各类肉制品样品45件,根据GB/T 5009.33-2010《食品中亚硝酸盐与硝酸盐的测定》,选用萘乙二胺分光光度法进行测定,并对检测结果进行统计分析。结果本次抽检的45件肉制品中亚硝酸盐含量的合格率为95.56%,各类肉制品中硝酸盐含量的合格率差异无统计学意义（χ2=2.193,P〉0.05）,超过限值（≥30 mg/kg）为2件,占4.44%。结论大理州市市售肉制品的生产加工中普遍使用亚硝酸盐基本规范,不过仍存在一定问题,有关部门还需加强监管。     

β2- and β3-adrenergic receptors drive COMT-dependent pain by increasing production of nitric oxide and cytokines

Decreased activity of catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines, contributes to pain in humans and animals. Previously, we demonstrated that development of COMT-dependent pain is mediated by both β₂- and β₃-adrenergic receptors (β₂ARs and β₃ARs). Here we investigated molecules downstream of β₂- and β₃ARs driving pain in animals with decreased COMT activity. Based on evidence linking their role in pain and synthesis downstream of β₂- and β₃AR stimulation, we hypothesized that nitric oxide (NO) and proinflammatory cytokines drive COMT-dependent pain. To test this, we measured plasma NO derivatives and cytokines in rats receiving the COMT inhibitor OR486 in the presence or absence of the β₂AR antagonist ICI118,551 + β₃AR antagonist SR59320A. We also assessed whether the NO synthase inhibitor L-N_G-nitroarginine methyl ester (L-NAME) and cytokine-neutralizing antibodies block the development of COMT-dependent pain. Results showed that animals receiving OR486 exhibited higher levels of NO derivatives, tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), interleukin-6 (IL-6), and chemokine (C-C motif) ligand 2 (CCL2) in a β₂- and β₃AR-dependent manner. Additionally, inhibition of NO synthases and neutralization of the innate immunity cytokines TNFα, IL-1β, and IL-6 blocked the development of COMT-dependent pain. Finally, we found that NO influences TNFα, IL-1β, IL-6, and CCL2 levels, whereas TNFα and IL-6 influence NO levels. Altogether, these results demonstrate that β₂- and β₃ARs contribute to COMT-dependent pain, at least partly, by increasing NO and cytokines. Furthermore, they identify β₂- and β₃ARs, NO, and proinflammatory cytokines as potential therapeutic targets for pain patients with abnormalities in COMT physiology.     

细菌硝酸盐还原中的关键酶影响细菌耐药性的研究进展

硝酸盐的还原是细菌氮代谢中最重要的生化反应之一.随着对细菌耐药机制的不断探索,氮代谢过程尤其是某些代谢酶对细菌耐药性的影响得以揭示.作为硝酸盐还原过程中的关键代谢酶,硝酸还原酶(nitrate reductase,NR)与亚硝酸还原酶(nitrite reductase,NiR)不仅催化着细菌体内硝酸盐的一系列还原反应,还从多方面影响了细菌的耐药性.本文综述了NR/NiR与细菌耐药性之间关系的最新研究进展,以期为新药物靶标的发现及提出新治疗措施提供依据.     

济宁市咸菜亚硝酸盐含量及消化道癌流行病学分析

为研究强致癌物亚硝胺的前体亚硝酸盐在咸菜中的含量，对２４个品种３９９份咸菜及原料等进行了检测。结果表明，不同地区、不同品种咸菜亚硝酸盐含量不同，盐碱地区含量较高，胡萝卜、青萝卜、大头菜含量较高，与腌渍时间、温湿度、生产工艺等有关。对本地区和全省同期消化道癌流行病学进行对照分析表明，其发病率较高，可能与经济落后、咸菜食用量较大有关。     

PC-Ⅰ型水处理设备净化水质效果分析

目的 了解PC-Ⅰ型水处理设备对水质的净化效果。方法 取经PC-Ⅰ型水处理器处理前后的二次供水的水质样品，按《生活饮用水卫生规范》(2001年6月版)进行检测。结果 二次供水经深度净化处理后，细菌总数由处理前的120个／ml下降到处理后的10个／ml。氨氮去除率为98．92％，亚硝酸盐氮去除率为99．40％，符合生活饮用水卫生标准。结论 PC-Ⅰ型饮用水深度净化处理设备能有效地降低饮用水中的氨氮、亚硝酸盐氮的浓度及细菌总数。     

Generation of High Yields of Syrian Hamster Cholangiocellular Carcinomas and Hepatocellular Nodules by Combined Nitrite and Aminopyrine Administration and Opisthorchis viverrini Infection

Combined administration of 0.1% nitrite and 0.1% aminopyrine in the drinking water for eight to ten weeks resulted in subsequent development of both hepatocellular nodules and cholangiofibrotic lesions/cholangiocellular carcinomas in Syrian golden hamsters. Additional prior dosing with Opisthorchis viverrini metacercariae (100/animal) induced inflammatory and proliferative changes in the livers of infected hamsters and was associated with a significant increase in yields of hepatocellular and cholangiocellular preneoplastic and neoplastic lesions. Thus, environmental factors thought to be casually related to the high levels of human liver cancer observed in the Northeastern provinces of Thailand were sufficient to bring about development of equivalent tumors in experimental animals. The results indicate that parasite associated liver injury and non-specific compensatory regeneration may play an important role in generation of both hepatocellular and cholangiocellular carcinomas in man.     

Augmenting Effect of a Nonmutagenic Fraction in Soy Sauce on Mutagenicity of 3-Diazotyramine Produced in the Nitrite-treated Sauce

When 25 kinds of Japanese soy sauce at a concentration of 5% were incubated with 50m M sodium nitrite (pH 2) at 37° for 1 hr, the reaction mixtures induced 34-834 (average 368 × 228) revertants per microliter of soy sauce equivalent in Salmonella typhimurium strain TA100 in the absence of S9 mix. The mutagen(s) formed was very unstable under natural daylight and a fluorescent lamp but quite stable under a yellow lamp as well as in the dark. In addition to the known precursors, i.e., tyramine and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-β-carboline, which caused weak mutagenesis, was found in the soy sauce. However, the sum of the activities of the three mutagen-precursors after nitrite treatment accounted for only a part of the mutagenicity of nitrite-treated soy sauce. There was in the soy sauce a factor which increased ninefold the mutagenicity of nitrite-treated tyramine, 3-diazotyramine. Therefore, tyramine was considered the principal precursor of the mutagen produced in the nitrite-treated soy sauce. These three precursors together with the mutagenicity augmentation accounted for all the mutagenicity of nitrite-treated sauce. The mutagenicity-augmenting factor in the soy sauce was nonmutagenic before and after nitrite treatment and was stable to heat and light irradiation.     

Effect of cyanide antidotes on the metabolic conversion of cyanide to thiocyanate

The excretion of thiocyanate following the administration of equitoxic doses of cyanide to unprotected mice and to animals pretreated with various cyanide antidotes has been studied.The results demonstrate that cyanide given alone or to animals pretreated with thiosulfate is extensively converted to thiocyanate. Animals pretreated with sodium nitrite or a combination of nitrite and sodium thiosulfate excreted even higher amounts of thiocyanate. This demonstrates that cyanide originally detoxified by combination with methemoglobin is ultimately converted to thiocyanate in the animal body.Pretreatment of animals with cobalt compounds (cobaltous chloride or dicobalt-EDTA) or a combination of cobalt compounds and thiosulfate resulted, on the other hand, in a less efficient conversion of cyanide to thiocyanate. The cyanide detoxified by trapping as highly undissociated cobalt-cyanide complexes is instead excreted in the urine, as demonstrated by detection of high amounts of cobalt ions and strongly complex-bound cyanide in the urine from animals treated with cobalt compounds and cyanide. A method for the determination of cyanide present as cobalt-cyanide complexes is described and its forensic application is proposed.     

Can Urinary Nitrite Results Be Used to Conduct Antimicrobial Option for Urinary Tract Infection in Children?

Objective

This study was performed to determine the relationship between urinary nitrite results and bacterial resistance to antimicrobial drugs in urinary tract infection of children.

Methods

In a cross-section study 119 children younger than 12 years with urinary tract infection were evaluated in Qazvin children''s hospital. Patients were divided into negative and positive nitrite groups depending on urinary nitrite test result. Rates of antibiotic resistance in the two groups were compared.

Findings

Sixty seven patients were in the negative nitrite group and 52 in the positive nitrite group. Resistance rates to ceftriaxone, trimethoprim sulfamethoxazole, ampicillin, gentamicin, amikacin, nalidixic acid, cephalothin and nitrofurantoin in the nitrite negative group were 7.5%, 31.3%, 50.7%, 11.9%, 9%, 3%, 14.9% and 11.9%, respectively. These values in the nitrite positive group were 21.2%, 28.8%, 63.5%, 7.7%, 5.8%, 1.9%, 9.6%, and 3.8%, respectively (P>0.05).

Conclusion

This study showed that there is no correlation between urinary nitrite results and bacterial resistance to antimicrobial drugs. Therefore, it seems that physicians should not adjust antibiotic therapy for UTI based on nitrite results.     

天津市部分市售熟肉制品亚硝酸盐含量的风险监测

目的对天津市部分市售熟肉制品中亚硝酸盐检出量进行风险监测。方法于2010年随机抽取天津市市售的180份熟肉制品样本,样本均采自天津市各个饭店。结果 180份样品中亚硝酸盐的检出量为0.93～158 mg/kg。合格174份,样本合格率为96.7%。结论该市熟肉制品中仍有少量样本亚硝酸盐超标,应继续加强监督检测和宣传工作。