Concentration of nitrite and nonthiol nitroso compounds in tissues as a high sensitive marker of leukocyte activity

This paper shows that the inflammation-induced appearance of nitrite and nonthiol nitroso compounds in the hen blood and cow milk is due to oxidation of dinitrosyl iron complexes (DNIC) and nitrosothiols (RSNO) by reactive oxygen species (ROS), which are produced by activated leukocytes. Since DNIC and RSNO are highly effective ROS scavengers, the content of nitrite and nonthiol nitroso compounds can be regarded as one of the most sensitive indicators of leukocyte activation.     

Mechanism of the relation between the content of nitro and nitroso compounds in amnion and allantois of chicken embryos and rate of posthatch chick growth

It is established that metabolism of nitric oxide (NO) in the chicken embryo and posthatch growth rate of chicks have a direct relation which is determined both by the genotype and by external factors influencing posthatch growth rate.     

Ascorbate-nitrite reaction: possible means of blocking the formation of carcinogenic N-nitroso compounds

The formation of carcinogenic N-nitroso compounds by the chemical reaction between nitrous acid and oxytetracycline, morpholine, piperazine, N-methylaniline, methylurea, and (in some experiments) dimethylamine was blocked by ascorbic acid. The extent of blocking depended on the compound nitrosated and on the experimental conditions. Urea and ammonium sulfamate were less effective as blocking agents. The possibility of in vivo formation of carcinogenic N-nitroso compounds from drugs could be lessened by the combination of such drugs with the ascorbic acid.     

外源性磷酸肌酸停跳液对儿童心肌保护作用的临床观察

目的:观察外源性磷酸肌酸对儿童心肌保护作用。方法:将30例心脏手术患儿随机分为实验组和对照组,每组15例。实验组采用含磷酸肌酸(CP)的st.Thomas 号停跳液,对照组采用st.Thomas 号停跳液,分别以手术中心脏停跳液用量、心脏停搏情况、心脏复跳情况、术后心律失常的发生率、血中肌钙蛋白T(Tn T)评价两种诱导停跳液的心肌保护作用。结果:(1)实验组停跳液能达到与对照组停跳液同样好的停跳效果;(2 )心脏自动复跳率、复跳后ST段改变、术后心律失常的发生率,两组间差异无显著性(P>0 .0 5 ) ;(3)实验组术中、术后6、2 4、4 8h的血Tn T水平均明显低于对照组(P<0 .0 1)。结论:磷酸肌酸停跳液较单纯晶体停跳液具有更好的心肌保护作用。     

Psilocybin: reaction with a fraction of rat brain

Psilocybin, a hallucinogen, formed a blue color with a subfraction of rat-brain mitochondria believed to contain nerve-ending particles. Color formation increased with pH, did not require oxygen, and involved a component that could not be solubilized. The effect was not shown by chemically related neuroactive compounds, such as bufotenine and serotonin, and was antagonized by only tyramine or ethylenediaminetetraacetic acid.     

Sulfur mustard: reaction with L-cells treated with 5-fluorodeoxyuridine

After exposure to 5-fluorodeoxyuridine, L-cells are considerably more sensitive to the lethal effect of sulfur mustard than after they have been released from this block by addition of thymidine and allowed to proceed into the G2 phase of the division cycle. Nevertheless, for both populations, the amounts of mustard bound per cell and per nucleus (expressed as the amount of mustard per unit of protein) were the same. Likewise, the amounts of mustard bound per unit of DNA were the same for both populations.     

Impact and inhibitory mechanism of phenolic compounds on the formation of toxic Maillard reaction products in food

As one of the dominant reactions occurring during thermal treatment of food, the Maillard reaction not only leads to the formation of aroma, browning color and taste compounds, but also contributes to the formation of some unpleasant toxic substances including acrylamide, heterocyclic amines and advanced glycation end products. Polyphenols, one of the most abundant antioxidants in the human diet, are contained in different kinds of foods. In this review, some recent studies on the impact of dietary polyphenols on the formation of acrylamide, heterocyclic amines and advanced glycation end products formed during the Maillard reaction are summarized, including the research work conducted with both chemical model systems and real food model systems; the possible inhibitory mechanisms of different polyphenols are also summarized and discussed in this review. Basically we found that some dietary polyphenols not only scavenge free radicals, but also react with reactive carbonyl species, thus lowering the formation of toxic Maillard reaction products. This review provides a useful theoretical foundation for the application of polyphenols in food safety, and suggests some directions for further study of natural products as inhibitors against the formation of toxic substances in thermally processed food.     

肉制品中亚硝酸盐含量超标原因分析

测定了潮州市面销售的8种品牌火腿的亚硝酸盐含量,结果显示,所测8份样品中有4份超标,抽检合格率为50%,其中亚硝酸盐残留量最高达29.77 mg/kg,超过国家标准(GB)规定1.49倍;超标检样主要集中在小型肉制品加工厂和个体食品加工者,提示消费者在选购火腿等肉制品时应注意品牌和生产厂家。     

Cytogenetic studies with cyclamate and related compounds

Cyclamate, cyclohexylamine, N-hydroxycyclohexylamine, and dicyclohexylamine can induce chromosomal damage in human leukocyte cultures.     

Macrophage cytotoxicity: role for L-arginine deiminase and imino nitrogen oxidation to nitrite

Previous studies have shown that cytotoxic activated macrophages cause inhibition of DNA synthesis, of mitochondrial respiration, and of aconitase activity in tumor target cells. An L-arginine-dependent biochemical pathway synthesizing L-citrulline and nitrite, coupled to an effector mechanism, is now shown to cause this pattern of metabolic inhibition. Murine cytotoxic activated macrophages synthesize L-citrulline and nitrite in the presence of L-arginine but not D-arginine. L-Citrulline and nitrite biosynthesis by cytotoxic activated macrophages is inhibited by NG-monomethyl-L-arginine, which also inhibits this cytotoxic effector mechanism. This activated macrophage cytotoxic effector system is associated with L-arginine deiminase activity, and the imino nitrogen removed from the guanido group of L-arginine by the deiminase reaction subsequently undergoes oxidation to nitrite. L-Homoarginine, an alternative substrate for this deiminase, is converted to L-homocitrulline with concurrent nitrite synthesis and similar biologic effects.     

反硝化细菌的筛选及其亚硝酸盐降解特性研究

从海水养殖池的底泥中筛选到6株反硝化细菌,其中对亚硝酸盐降解力最强的1株菌JN1初步鉴定为假单胞菌,研究了JN1的亚硝酸盐降解特性,结果表明:JN1具有高效降解转化亚硝酸钠的能力,其适宜降解条件为:亚硝酸钠浓度1 000~4 000 mg.L-1,菌种接种量5%(v/v),培养基装量100 mL(250 mL容量),中量充气发酵,发酵时间18~30 h,发酵pH值6.5~7.5。     

谷胱甘肽存在条件下NO2-对玉米植株干旱胁迫的缓解作用

【目的】研究谷胱甘肽(GSH)还原亚硝酸钠(NaNO2)生成S-亚硝基谷胱甘肽(GSNO)所释放NO对玉米幼苗抗旱性的影响。【方法】以玉米品种"郑单958"为供试材料,采用盆栽试验,分别用NO-2+GSH合成的不同浓度GSNO(50,250,500,800,1 000μmol/L)熏蒸处理三叶期的玉米幼苗,通过控制浇水进行干旱胁迫,以未经GSNO处理的玉米幼苗(0μmol/L GSNO)为干旱对照,通过测定干旱胁迫期间玉米的生长、生理指标,分析GSNO对干旱胁迫条件下玉米植株生长、抗氧化酶活性、膜脂过氧化程度的影响。【结果】干旱胁迫7d后,50~1 000μmol/L GSNO处理的玉米幼苗较干旱对照生长更好,其中500μmol/L GSNO处理玉米幼苗的株高、茎粗和叶面积分别较干旱对照提高32.26%,45.83%和53.13%。GSNO处理能够显著增强干旱胁迫玉米幼苗的超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)、过氧化氢酶(CAT)和抗坏血酸氧化酶(APX)的活性,相应减少过氧化氢(H2O2)和超氧阴离子(O-·2)含量,降低膜脂的过氧化伤害。GSNO处理还能够维持干旱胁迫下玉米幼苗光合色素的相对稳定性,降低离体叶片的失水速率,其变化趋势表现为500μmol/L50μmol/L1 000μmol/L。【结论】GSNO处理能明显改善玉米的抗旱性,其发挥作用的最佳浓度为500μmol/L。     

Lunar organic compounds: search and characterization

The carbon concentration in Apollo 11 lunar fine material is of the order of 200 ppm. By far the largest single amount of this carbon appears to be in carbon monoxide. Some of this seems to be in the form of gas bubbles in the glass spheres, but most of it could be in some complex form other than gas. This result would be consistent with the idea that most of the fines passed through a high temperature and that the carbon was oxidized by mineral oxides at that time.     

石灰性土壤中亚硝态氮的累积机理和条件

【目的】探讨石灰性土壤中亚硝态氮的累积机理和条件,为氮素管理和环境保护提供依据。【方法】采用室内培养的方法,探讨了不同氮肥种类、氮肥用量、土壤水分含量和温度对土壤亚硝态氮产生和累积的影响。【结果】在培养条件下(土壤水分含量为田间持水量(WHC)的60%,温度为25℃),硝态氮肥处理的土壤中几乎未检测到亚硝态氮;3种铵态氮肥处理均有不同程度的亚硝态氮累积,土壤中亚硝态氮含量依次为硫酸铵>尿素>硝酸铵;土壤中亚硝态氮含量与铵态氮含量呈极显著正相关,与硝化速率呈极显著负相关。土壤中亚硝态氮含量随氮肥施用量的增加而增大;随土壤水分含量的增加而上升。培养温度为45℃时,土壤亚硝态氮含量最小;培养温度为25℃和35℃时,土壤亚硝态氮含量差异较小,且均高于45℃时。土壤中亚硝态氮累积总量与氮肥用量和土壤水分含量均呈显著直线正相关;亚硝态氮最大含量与土壤水分含量呈显著直线正相关,出现在硝化作用5~10 d后。【结论】在该试验培养条件下,硝化过程是石灰性土壤亚硝态氮的来源,土壤亚硝态氮累积量随氮肥施用量和土壤水分含量的增加而增大,其最适宜累积的温度为25℃。