A rapid method for the determination of nitrate and nitrite by chemiluminescence

Nitrite and nitrate + nitrite can be determined by selective chemical reduction to nitric oxide which is measured using a chemiluminescence analyser. The reducing agents are sodium iodide in acetic acid for nitrite and ferrous ammonium sulphate-ammonium molybdate for nitrate + nitrite. The concentrations of the reducing agents have been optimized to obtain the maximum yield of nitric oxide and the minimum coefficient of variation. Under these conditions, it is possible to inject repeated samples into the refluxing reducing agents and to obtain rapid evolutions of nitric oxide from which the determinations can be made. Nitric oxide has also been produced using the nitrite reagents from organic nitrites, a S-nitrosothiol, a pseudonitrole and N-nitrosamines. Similarly, an organic nitrate and some C-nitroso compounds respond to the method for nitrate but only to the extent of a yield of nitric oxide of about 10% of the theoretical. Very low or zero responses were evident from aliphatic and aromatic C-nitro compounds but not omega-N-nitroarginine which gave a large yield of nitric oxide using the reagents for nitrate. In general, however, concentrations of nitrate will be in considerable excess of those of related compounds which would interfere with the determinations. Nitrate can be determined either by difference in its mixtures with nitrite or by prior removal of the nitrite using ascorbic acid provided oxygen and nitric oxide are removed by degassing with nitrogen.     

Simultaneous microbial reduction of iron(III) and arsenic(V) in suspensions of hydrous ferric oxide

Bacterial reduction of arsenic(V) and iron(III) oxides influences the redox cycling and partitioning of arsenic (As) between solid and aqueous phases in sediment-porewater systems. Two types of anaerobic bacterial incubations were designed to probe the relative order of As(V) and Fe(III) oxide reduction and to measure the effect of adsorbed As species on the rate of iron reduction, using hydrous ferric oxide (HFO) as the iron substrate. In one set of experiments, HFO was pre-equilibrated with As(V) and inoculated with fresh sediment from Haiwee Reservoir (Olancha, CA), an As-impacted field site. The second set of incubations consisted of HFO (without As) and As(III)- and As(V)- equilibrated HFO incubated with Shewanella sp. ANA-3 wild-type (WT) and ANA-3deltaarrA, a mutant unable to produce the respiratory As(V) reductase. Of the two pathways for microbial As(V) reduction (respiration and detoxification), the respiratory pathway was dominant under these experimental conditions. In addition, As(III) adsorbed onto the surface of HFO enhanced the rate of microbial Fe(III) reduction. In the sediment and ANA-3 incubations, As(V) was reduced simultaneously or prior to Fe(III), consistent with thermodynamic calculations based on the chemical conditions of the ANA-3 WT incubations.     

气调包装材料对厚皮甜瓜采后呼吸途径的影响

采用聚乙烯醇（PVOH）、聚对苯二甲酸乙二醇酯（PET）、聚丙烯（PP）3种包装材料在同一气调比例下对新疆厚皮甜瓜进行贮藏实验,每10 d使用液相氧电极仪测定不同呼吸途径:糖酵解（EMP）、三羧酸循环（TCA）、戊糖磷酸途径（PPP）、细胞色素系统途径（CP）、交替途径（AP）、总呼吸（Total）的呼吸速率;采后第70 d统计各处理组甜瓜的腐烂率、好果率情况。结果表明:在贮藏温度为（3±1）℃,相对湿度为75%⁸5%条件下,甜瓜装入三种包装材料膜内充入O₂、CO₂浓度分别约为5.59%、1.80%后与CK相比较,采后各处理组总呼吸途径速率均得到有效抑制,其中PP处理组采后各呼吸速率均小于其它三组,EMP路径呼吸速率受环境影响转移到以TCA路径为主。至贮期结束后,PP包装膜处理的甜瓜贮藏品质相对最好,可以有效降低呼吸速率、延缓甜瓜的成熟衰老、防止病害的发生;CK贮藏效果最差。      

Dietary Nitrate,Nitric Oxide,and Cardiovascular Health

Emerging evidence strongly suggests that dietary nitrate, derived in the diet primarily from vegetables, could contribute to cardiovascular health via effects on nitric oxide (NO) status. NO plays an essential role in cardiovascular health. It is produced via the classical L-arginine–NO-synthase pathway and the recently discovered enterosalivary nitrate–nitrite–NO pathway. The discovery of this alternate pathway has highlighted dietary nitrate as a candidate for the cardioprotective effect of a diet rich in fruit and vegetables. Clinical trials with dietary nitrate have observed improvements in blood pressure, endothelial function, ischemia-reperfusion injury, arterial stiffness, platelet function, and exercise performance with a concomitant augmentation of markers of NO status. While these results are indicative of cardiovascular benefits with dietary nitrate intake, there is still a lingering concern about nitrate in relation to methemoglobinemia, cancer, and cardiovascular disease. It is the purpose of this review to present an overview of NO and its critical role in cardiovascular health; to detail the observed vascular benefits of dietary nitrate intake through effects on NO status as well as to discuss the controversy surrounding the possible toxic effects of nitrate.     

Oxygen addition and sterol synthesis in Saccharomyces cerevisiae during enological fermentation

Under anaerobic conditions, yeast growth normally requires oxygen in order to favour the synthesis of sterols and unsaturated fatty acids. However, in such conditions, superfluous oxygen consumption by yeast cells is observed. The superfluous oxygen consumed by the yeast cells appears to be not related to classical respiration, but mainly to the operation of several alternative oxygen consumption pathways. In this study, the potential relationship between this superfluous oxygen consumption and the yeast sterol synthesis pathway was investigated during enological fermentation. Additions of small (7 mg l(-1)) and excess (37 mg l(-1)) amounts of oxygen at the end of cell growth phase were used as a method of comparing oxygen consumption by normal synthetic pathways with that by alternative respiration pathways. The superfluous oxygen consumption by yeast cells during fermentation seemed not to alter and strongly favoured fermentation kinetics and cell biomass formation. However, a marked decrease of the orderliness of the membrane phospholipids is observed, which is not related to the drop of cell viability. After oxygen additions, squalene contents of the cells decreased, while the relative proportions of ergosterol or its precursors in the total sterol fraction did not correlatively increase. It was further found that an oxygen-dependent sterol degradation occurred when oxygen was added in excess amounts with respect to the cellular requirements for sterol synthesis. At present, this modification of the sterol contents of yeast membranes has not been related to any physiological parameters.     

DNP和ATP对Phomopsis longanae Chi侵染的龙眼果实病害发生、能荷状态和呼吸代谢的调控

与拟茎点霉接种果实相比,DNP能提高拟茎点霉接种果实的病害指数和果皮褐变指数,提高果实呼吸速率和果皮COX、AAO、PPO活性及NAD和NADH含量,降低果皮NADK活性和NADP、NADPH含量及能荷值。而ATP则能降低拟茎点霉接种果实的病害指数和果皮褐变指数,降低果实呼吸速率和果皮COX、AAO、PPO活性及NAD和NADH含量,提高果皮NADK活性和NADP、NADPH含量,维持较高的果皮能荷值。据此认为,DNP处理促进拟茎点霉侵染所致龙眼果实采后病害发生,与DNP加剧能量亏缺、削弱磷酸戊糖呼吸代谢途径及增强COX、AAO和PPO等呼吸末端氧化酶活性有关;而ATP处理延缓拟茎点霉侵染所致龙眼果实采后病害发生,与ATP维持较高的能荷值、增强磷酸戊糖呼吸代谢途径及降低COX、AAO、PPO等呼吸末端氧化酶活性有关。     

The influence of nitrate on the physiology of the yeast Dekkera bruxellensis grown under oxygen limitation

A previous study showed that the use of nitrate by Dekkera bruxellensis might be an advantageous trait when ammonium is limited in sugarcane substrate for ethanol fermentation. The aim of the present work was to evaluate the influence of nitrate on the yeast physiology during cell growth in different carbon sources under oxygen limitation. If nitrate was the sole source of nitrogen, D. bruxellensis cells presented slower growth, diminished sugar consumption and growth‐associated ethanol production, when compared to ammonium. These results were corroborated by the increased expression of genes involved in the pentose phosphate (PP) pathway, the tricarboxylic acid (TCA) cycle and ATP synthesis. The presence of ammonium in the mixed medium restored most parameters to the standard conditions. This work may open up a line of investigation to establish the connection between nitrate assimilation and energetic metabolism in D. bruxellensis and their influence on its fermentative capacity in oxygen‐limited or oxygen‐depleted conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Relationship between nitrate/nitrite reductase activities in meat associated staphylococci and nitrosylmyoglobin formation in a cured meat model system

Quantitative determination of catalase, nitrate reductase, nitrite reductase and nitric oxide synthase activities (NOS) was performed on 11 different bacterial strains, mainly staphylococci, isolated from fermented sausages, bacon brine or cured meat products. All except one strain possessed catalase activity in the range from 1.0 to 6.1 μmol min^− 1 ml^− 1. Ten out of 11 bacteria strains showed nitrate reductase activity in the range between 50 and 796 nmol min^− 1 ml^− 1 and nine showed nitrite reductase activity in the range between 6 and 42 nmol min^− 1 ml^− 1. No evidence of NOS activity of the selected strains was detected. In a colour formation assay containing myoglobin all strains affected nitrosylmyoglobin (MbFe^IINO) formation in assays containing nitrite, whereas only strains having nitrate reductase activity generated MbFe^IINO in assays containing nitrate as the sole nitrosylating agent. The quantitative nitrate and nitrite reductase activity did not fully explain or correlate well with the observed rate of formation of MbFe^IINO, which seemed to be more affected by the growth rate of the different strains. The mechanism of the reduction of nitrite into NO of strains not having nitrite reductase activity remains to be fully elucidated, but could be due to a dual-mode action of nitrate reductase capable of acting on nitrate.     

Non-respiratory oxygen consumption pathways in anaerobically-grown Saccharomyces cerevisiae: evidence and partial characterization

Despite the absence of an alternative mitochondrial ubiquinol oxidase, Saccharomyces cerevisiae consumes oxygen in an antimycin A- and cyanide-resistant manner. Cyanide-resistant respiration is typically used when the classical respiratory chain is impaired or absent (i.e in anaerobically-grown cells shifted to normoxia or in respiratory-deficient cells). We characterized the non-respiratory oxygen consumption pathways operating during anoxic-normoxic transitions in glucose-repressed resting cells. High-resolution oxygraphy confirmed that the cellular non-respiratory oxygen consumption pathway is sensitive to high concentrations of cyanide, azide, SHAM and TTFA, and revealed several new characteristics. First, the use of sterol biosynthesis inhibitors showed that this pathway makes a considerable contribution (about 25%) to both endogenous and glucose-dependent oxygen consumption. Anaerobically-grown glucose-repressed cells exhibited high apparent oxygen affinities (K(m) for oxygen = 0.5-1 micro M), even in mutants deficient in respiration or sterol synthesis. Exogeneously added glucose and endogenous stored carbohydrates were the only substrates that were efficient for cellular oxygen consumption (apparent K(m) for exogenous glucose = 2-3 mM). On the other hand, fluorimetric measurements of the cellular NAD(P)H pool showed that the cellular oxygen consumption (sterol biosynthesis and unknown pathways) was dependent more on the intracellular level of NADPH than of NADH. High oxygen affinity NADPH-dependent oxygen consumption systems were thought to be mainly localized in microsomal membranes, and several data indicated a significant contribution made by uncoupled p450 systems, together with still uncharacterized systems. Such activities are associated in vitro with a massive production of O(2) (.-) and, to a lower extent, H(2)O(2) and a likely concomitant production of H(2)O.     

Cellular and transcriptional response of Pseudomonas stutzeri to quantum dots under aerobic and denitrifying conditions

Pseudomonas stutzeri was exposed to quantum dots (QDs) with three different surface coatings (anionic polymaleic anhydride-alt-1-octadecene (PMAO), cationic polyethylenimine (PEI), and carboxyl QDs) under both aerobic and anaerobic (denitrifying) conditions. Under aerobic conditions, toxicity (assessed per growth inhibition) increased from PMAO to carboxyl to PEI QDs. The positive charge of PEI facilitated direct contact with negatively charged bacteria, which was verified by TEM analysis. Both PMAO and PEI QDs hindered energy transduction (indicated by a decrease in cell membrane potential), and this effect was most pronounced with PEI QDs under denitrifying conditions. Up-regulation of denitrification genes (i.e., nitrate reductase narG, periplasmic nitrate reductase napB, nitrite reductase nirH, and NO reductase norB) occurred upon exposure to subinhibitory PEI QD concentrations (1 nM). Accordingly, denitrification activity (assessed per respiratory nitrate consumption in the presence of ammonia) increased during sublethal PEI QD exposure. However, cell viability (including denitrification) was hindered at 10 nM or higher PEI QD concentrations. Efflux pump genes czcB and czcC were induced by PEI QDs under denitrifying conditions, even though Cd and Se dissolution from QDs did not reach toxic levels (exposure was at pH 7 to minimize hydrolysis of QD coatings and the associated release of metal constituents). Up-regulation of the superoxide dismutase (stress) gene sodB occurred only under aerobic conditions, likely due to intracellular production of reactive oxygen species (ROS). The absence of ROS under denitrifying conditions suggests that the antibacterial activity of QDs was not due to ROS production alone. Overall, this work forewarns about unintended potential impacts to denitrification as a result of disposal and incidental releases of QDs, especially those with positively charged coatings (e.g., PEI QDs).     

Nitric oxide production during endotoxin-induced mastitis in the cow

Nitric oxide production was measured during endotoxin-induced mastitis. One hour after morning milking, the right hind quarters of 15 cows were infused with saline containing Escherichia coli endotoxin. Left hind control quarters were infused with saline only. At varying intervals before and after infusion, diagnostic markers of mastitis were recorded and nitric oxide production was evaluated by measuring nitrite plus nitrate levels in milk. In endotoxin-infused quarters, a significant increase in nitrite plus nitrate concentrations was observed 3 h postinfusion; concentrations decreased to preinfusion levels within 48 h. This change indicates that significant amounts of nitric oxide are released during endotoxin-induced mastitis. At 3 different time points, somatic cells were harvested from milk samples, plated, and maintained in culture for 24 h. The concentration of nitrite plus nitrate in medium from cells harvested 12 h postinfusion was increased, suggesting that nitric oxide is released, at least in part, by milk somatic cells. In a second set of experiments, we evaluated nitric oxide production when animals were infused with endotoxin and aminoguanidine, a specific inhibitor of the inducible form of nitric oxide synthase. In cows treated with aminoguanidine, the increase in nitrite plus nitrate observed after endotoxin infusion was prevented. These results suggest that nitric oxide production during endotoxin-induced mastitis resulted from the activity of the inducible form of nitric oxide synthase. They also support a possible involvement for nitric oxide in the inflammatory reaction observed during mastitis.     

Dissimilatory arsenate reduction by a facultative anaerobe, Bacillus sp. strain SF-1

Bacillus sp. strain SF-1, isolated first as a selenate-reducing bacterium, was characterized as a novel arsenate-reducing bacterium. Strain SF-1 rapidly reduced 10 mM levels of arsenate to arsenite with concomitant cell growth and lactate oxidation under anoxic conditions, indicating that arsenate can act as the terminal electron acceptor for anaerobic respiration (dissimilatory arsenate reduction). Strain SF-1 can use various organic compounds including synthetic sewage mainly composed of peptone and meat extract as the electron donors for arsenate reduction. Although strain SF-1 can grow aerobically, which is very rare for dissimilatory arsenate-reducing bacteria, the presence of oxygen inhibited the arsenate reduction. On the other hand, the presence of nitrate or selenate, which can support the growth of strain SF-1 as electron acceptors, did not significantly inhibit the arsenate reduction. Arsenate-reducing activity, that is, arsenate reductase, was exhibited in strain SF-1 only when grown on arsenate, but the enzyme could not reduce other oxyanions including nitrate and selenate. It was presumed that arsenate reduction was carried out by an enzyme system separate from those of nitrate and selenate reduction, and the arsenate reductase was inducible and specific for arsenate. These results suggest that strain SF-1 may be utilized for extracting arsenic from contaminated soil for the purpose of bioremediation.     

硝酸盐促进环磷酸腺苷发酵合成的生理机制研究

目的：阐明硝酸盐促进环磷酸腺苷发酵合成的生理机制。方法：首先通过摇瓶实验确定硝酸钠最适添加条件,并在发酵罐上进行添加硝酸钠的cAMP发酵实验,然后对发酵过程动力学数据、硝酸盐代谢、还原力水平、关键酶活性、氨基酸水平和能量代谢进行分析。结果：确定在发酵24 h添加3 g/L-broth硝酸钠为最适条件,cAMP发酵产量和得率分别达到5.02 g/L和0.097 g/g,比对照批次分别提高了22.7%和29.8%,发酵性能得到明显提升。硝酸盐利用过程消耗了大量NADPH,缓解了对6-磷酸葡萄糖脱氢酶的抑制作用,同时糖酵解途径受到抑制而磷酸戊糖途径和三羧酸循环中关键酶活性明显提高,更多碳流分配到产物合成途径。此外,胞内前体氨基酸水平、NADH/NAD⁺和ATP/AMP均得到明显提高,为cAMP发酵合成提供了物质和能量基础。结论：硝酸盐利用过程消耗了大量的还原力,改变了代谢流分配情况,提高了胞内氨基酸水平和ATP合成,进而促进cAMP的发酵合成。硝酸盐作用机制的阐明,为提高核苷酸类发酵产品的生产水平提供了参考。     

Metabolic flux analysis of RQ-controlled microaerobic ethanol production by Saccharomyces cerevisiae

Microaerobic ethanol production by Saccharomyces cerevisiae CBS 8066 was investigated at different growth rates in respiratory quotient (RQ)-controlled continuous culture. The RQ was controlled by changing the inlet gas composition by a feedback controller while keeping other parameters constant. The ethanol yield increased slightly from the anaerobic values with decreasing RQ, reaching a broad maximum at RQ 20 to 12. There was little or no glycerol production at RQ values below 17 over a wide range of dilution rates. Metabolic flux analysis revealed that a decrease in the ethanol yield at RQ 6 coincided with the cyclic, oxidative operation of the TCA cycle reactions. The model indicated that respiratory dissimilation of glucose only occurs when the oxygen uptake rate is high enough to completely substitute for glycerol formation. The cytosolic and the mitochondrial NADH balances were important for determining the flux distributions. The smallest deviations between estimated and measured product yields were obtained when the unknown co-factor requirements of a limited number of biosynthetic reactions were chosen so that the amount of excess NADH formed in biosynthesis was minimized. The biomass yield was positively correlated with the net amount of NADH reoxidized in respiration and glycerol formation, indicating that the turnover of excess NADH from biosynthesis is an important factor influencing the biomass yield under oxygen-limiting conditions.     

Key role for transketolase activity in erythritol production by Trichosporonoides megachiliensis SN-G42

Erythritol is an important sugar alcohol industrially produced only by fermentation. The highly osmophilic yeast-like fungi, Trichosporonoides megachiliensis SN-G42, enables commercial production of erythritol with a high conversion from glucose to erythritol of more than 47%. However, the microbial production pathway of erythritol remains unclear. In the present study, the activities of enzymes in the pentose phosphate pathway of Trichosporonoides megachiliensis SN-G42 used for industrial erythritol production were measured under various culture conditions to examine the production mechanism and the key-enzymes.As a result, the various enzyme activities of this organism are revealed in the pentose phosphate pathway, i.e., those of hexokinase, glucose-6-phosphate dehydrogenase, gluconate dehydrogenase, transketolase, transaldolase, and erythrose reductase. In the cultures in which erythritol was produced after completion of cell growth, the enzyme activities of the pentose phosphate pathway were higher than those of the TCA cycle. In particular, transketolase activity was correlated with erythritol productivity under various production cultures with different agitation speeds and thiamine concentrations.These results suggest that erythritol may be produced mainly through the pentose phosphate pathway. In addition, the high activity of transketolase is required to produce abundant intermediates, which results in high erythritol productivity. As such, transketolase appears to be a key-enzyme for erythritol production in the organism studied.     

Characterization of the respiration‐induced yeast mitochondrial permeability transition pore

When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane, dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable through the yPTP in an industrial yeast strain, Yeast Foam. The presence of oligomycin, an inhibitor of ATP synthase, allowed for respiration‐induced mannitol permeability in mitochondria from this strain. Potassium (K⁺) had varied effects on the respiration‐induced yPTP, depending on the concentration of the respiratory substrate added. At low respiratory substrate concentrations K⁺ inhibited respiration‐induced yPTP opening, while at high substrate concentrations this effect diminished. However, at the high respiratory substrate concentrations, the presence of K⁺ partially prevented phosphate inhibition of yPTP opening. Phosphate was found to inhibit respiration‐induced yPTP opening by binding a site on the matrix space side of the inner membrane in addition to its known inhibitory effect of donating protons to the matrix space to prevent the pH change necessary for yPTP opening. The respiration‐induced yPTP was also inhibited by NAD, Mg²⁺, NH₄⁺ or the oxyanion vanadate polymerized to decavanadate. The results demonstrate similar effectors of the respiration‐induced yPTP as those previously described for the ATP‐induced yPTP and reconcile previous strain‐dependent differences in yPTP solute selectivity. Copyright © 2013 John Wiley & Sons, Ltd.     

小檗碱活化AMPK-eNOS减轻油酸所致人主动脉内皮细胞损伤

目的：考察小檗碱对油酸所致内皮细胞损伤的保护作用,并探究其作用机制。方法：以体外培养人主动 脉内皮细胞系（human aorta endothelial cells,HAEC）为受试对象;分别以油酸、油酸联合小檗碱、油酸联合单 磷酸腺苷活化蛋白激酶（adenosine monophosphate-activated protein kinase,AMPK）激活剂（AICAR）或抑制剂 （Compound C）处理HAEC;采用油红O染色法观察细胞内脂滴合成;采用比色法检测细胞内甘油三酯、总胆 固醇含量,硝酸还原酶法检测NO的水平,2’,7’-二氯荧光黄双乙酸盐探针检测细胞内总活性氧（reactive oxygen species,ROS）水平,Western Blotting检测细胞总AMPK、内皮型一氧化氮合酶（endothelial nitric oxide synthase, eNOS）及其磷酸化（p-AMPK、p-eNOS）水平。结果：油酸可浓度依赖性地抑制细胞增殖,小檗碱组各项指标 较正常对照组无显著性差异,油酸联合小檗碱组的细胞活性较油酸组明显好转（P＜0.01）。与正常对照组比较, 油酸组的脂质浸润程度明显,油酸在不同浓度下使内皮细胞的脂质含量呈剂量依赖性增加,加入小檗碱可明显减 少这种脂质堆积。油酸组的NO水平较正常对照组明显减少,小檗碱能显著抑制油酸所致的内皮NO水平的减少, 并且减少由于油酸所致的ROS水平的升高;油酸抑制了AMPK的活化,使p-AMPK和p-eNOS的蛋白水平明显降低 （P＜0.01）;小檗碱可明显逆转油酸所致AMPK和eNOS磷酸化水平下降,Compound C可拮抗其作用。结论：小檗 碱可减轻油酸所致血管内皮细胞损伤,或与其活化AMPK/eNOS信号相关。     

Inhibitory effects of glycoprotein isolated from Laminaria japonica on lipopolysaccharide-induced pro-inflammatory mediators in BV2 microglial cells

Chronic microglial activation endangers neuronal survival through release of various toxic pro-inflammatory molecules; therefore, negative regulators of microglial activation have been identified as potential therapeutic candidates for use in treatment of many neurological diseases. In this study, we conducted an investigation of the inhibitory effects of glycoprotein isolated from Laminaria japonica (LJGP) on production of lipopolysaccharide (LPS)-induced pro-inflammatory mediators in BV2 microglial cells. Data from the study indicated that treatment with LJGP resulted in significant inhibition of excessive production of nitric oxide and prostaglandin E(2) in LPS-stimulated BV2 cells. LJGP also attenuated expression of inducible nitric oxide synthase, cyclooxygenase-2, and pro-inflammatory cytokines, including interleukin-1β and tumor necrosis factor-α. In addition, LJGP exhibited anti-inflammatory properties by suppression of nuclear factor-kappaB activation and downregulation of extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and Akt pathways. These findings suggest LJGP may provide neuroprotection through suppression of the proinflammatory pathway in activated microglia.     

Modulation of steroid activity in chronic inflammation: a novel anti-inflammatory role for curcumin

The expression of NF-kappaB (NF-kappaB)-dependent pro-inflammatory genes in response to oxidative stress is regulated by the acetylation-deacetylation status of histones bound to the DNA. It has been suggested that in severe asthma and in chronic obstructive pulmonary disease (COPD) patients, oxidative stress not only activates the NF-kappaB pathway but also alters the histone acetylation and deacetylation balance via post-translational modification of histone deacetylases (HDACs). Corticosteroids have been one of the major modes of therapy against various chronic respiratory diseases such as asthma and COPD. Failure of corticosteroids to ameliorate such disease conditions has been attributed to their inability to either recruit HDAC2 or to the presence of an oxidatively modified HDAC2 in asthmatics and COPD subjects. Naturally occurring polyphenols such as curcumin and resveratrol have been increasingly considered as safer nutraceuticals. Curcumin is a polyphenol present in the spice turmeric, which can directly scavenge free radicals such as superoxide anion and nitric oxide and modulate important signaling pathways mediated via NF-kappaB and mitogen-activated protein kinase pathways. Polyphenols also down-regulate expression of pro-inflammatory mediators, matrix metalloproteinases, adhesion molecules, and growth factor receptor genes and they up-regulate HDAC2 in the lung. Thus, curcumin may be a potential antioxidant and anti-inflammatory therapeutic agent against chronic inflammatory lung diseases.     

寡糖素诱导冬枣果实水杨酸信号变化的研究

以采后冬枣为实验对象,研究寡糖素诱导处理对冬枣果实抗病反应过程中水杨酸信号分子的影响.实验结果表明,冬枣果实在寡糖素诱导作用下,12h内果实水杨酸含量升高,增加量达60.60％,至诱导后24h果实内游离水杨酸含量急剧下降,水杨酸信号与果实钙离子通道的抑制作用相互协作,共同参与了寡糖素诱导的苯丙氨酸代谢酶活性升高过程.