Nitric oxide donors offer protection to RBC from storage lesion

BackgroundRed blood cell (RBC), which is the most commonly transfused blood component, due to its ability to save a life in absence of any other blood components, can be stored up to maximum 6 weeks by following standard preservation procedure. During storage, RBC undergoes various biophysical and biochemical changes (commonly known as storage lesion) for which blood transfusion with “old RBC” shows a lot of clinical problems especially relevant to critically ill patients. Recent research on S-nitrosylation of haemoglobin to improve oxygen delivery of banked blood revealed the important role of nitric oxide (NO) in protecting storage lesion.Materials and methodsIn the present study, we used various “NO donating” chemicals with different NO release dynamics and chemistries in RBC storage cocktails to test the effects of NO on storage lesion. Changes in different storage markers were evaluated after 7 days storage of pre-treated RBC.ResultsAll the NO donors have shown protection against hemolysis. However, S-nitroso glutathione (GSNO) ranks first in shielding RBCs from storage lesion and additionally, it helps in elevating the value of 2, 3-di phosphoglycerate (2, 3-DPG), improving the RBC membrane fluidity and decreasing the adhesion towards endothelial monolayer.DiscussionPresent study reveals that NO released from NO donors confers protection against storage lesions of the RBC. Further, the study confirms that pre-treatment with GSNO, a NO donor and a nitrosylating agent, ensures the best protection to RBC during low temperature storage, when compared to other NO donor treatments.     

A rapid method for simultaneous determination of nitrate,nitrite and thiocyanate in milk by CZE-UV using quaternary ammonium chitosan as electroosmotic flow inverter

This paper proposes a rapid method for the simultaneous determination of nitrate, nitrite and thiocyanate in different milk samples (cow, goat and soy) using capillary zone electrophoresis. The separations were conducted in a fused silica capillary dynamically coated with quaternary ammonium chitosan, with a total length of 48.5 cm (40 cm effective x 75 μm internal diameter) and direct detection in the UV region at 210 nm. The background electrolyte (BGE) was composed of 30 mmol L⁻¹ of aminocaproic acid and 24 mmol L¹ of perchloric acid (pH 3.85).A typical anodic electroosmotic flow of -31 × 10^-9 m² V⁻¹ s⁻¹ was observed at the pH of the separations. Bromate was used as the internal standard. The samples were injected by hydrodynamic pressure (50 mbar, 40 s) and the separation voltage was −30 kV. The proposed method was validated and presented good linearity (R²> 0.99) in the linear range of 0.1–4.0 mg L⁻¹. The ranges of the limit of detection (LOD) and limit of quantification (LOQ) were 0.03-0.04 and 0.05–0.07 mg L⁻¹, respectively. The intra-day and inter-day precision values were better than 4.2 and 8.7 %, respectively. Recovery values ranged from 85 to 104% for the different samples of milk. The proposed method was applied in 12 commercial samples with run times of less than 2 min. The good analytical performance indicates that the method proposed is a promising alternative for the determination of nitrate, thiocyanate and nitrite in milk samples.     

唾液硝酸盐、亚硝酸盐检测方法的探讨

目的 通过比较几种不同测定唾液硝酸盐、亚硝酸盐含量的方法来寻求最佳测定唾液微量硝酸盐、亚硝酸盐的标准方法.方法 比较经典的Griess法、镉柱法和高压液相色谱法(HPLC)对含不同浓度的硝酸盐、亚硝酸盐标准品以及10位健康志愿者混合唾液样本中硝酸盐、亚硝酸盐含量的最低检出限和硝酸盐、亚硝酸盐回收率.结果 Griess法和镉柱法测定唾液硝酸盐、亚硝酸盐的最低检出限NO-3为10ng/μl,NO-2为1ng/μl,回收率为91.2%;HPLC法测定唾液硝酸盐、亚硝酸盐的最低检出限为NO-3为0.8ng/μl,NO-2为0.1ng/μl,回收率达到97.6%.结论 HPLC在微量硝酸盐、亚硝酸盐检测中的灵敏度明显高于经典的Griess法.     

Nitrite reduction in acidic solution at a GC/Eastman-AQ-Os(bpy)32+-PVP composite modified electrode

The negatively charged polymer polyester sulfonic acid (Eastman-AQ, abbreviated to AQ), positively charged polymer polyvinyl pyridine (PVP) and mediator Os(bpy)₃²⁺ were used to construct composite modified glassy carbon (GC) electrodes (abbreviated to GC/AQ-Os(bpy)₃²⁺-PVP). The reduction of NO₂^? in acidic solution was taken as a model reaction to explore the properties of the modified electrode. On the steady state polarization curve of NO₂^? reduction there were two well-developed waves with much enhanced plateau current densities and positively shifted half-wave potentials compared with bare GC electrodes. In 0.05 mol/l H₂SO₄ + 5 mmol/l NO₂^? the modified electrode exhibited plateau current densities of 723 and 1153 μA cm^?2 and half-wave potential shifts of 0.29 and 0.56 V for the first and second current wave, respectively, showing promising potential for nitrite detection. The catalytic activity for NO₂^? reduction did not decrease appreciably over 4 months. A number of relevant kinetic and thermodynamic parameters are estimated experimentally. NO₂^? reduction at the composite modified electrodes is suggested to follow the SR mechanism (pure kinetic conditions involving mutual compensation between a catalytic reaction and substrate diffusion in the film in addition to diffusion in the solution phase) according to the Savéant–Andrieux theory.     

Electroreduction of methyl viologen in the presence of nitrite. Its influence on enzymatic electrodes

The electroreduction of methyl viologen (MV) in the presence of nitrite was studied by cyclic voltammetry. A catalytic wave for the reduction of MV²⁺ was observed at ?0.740 V for which an EC catalytic mechanism is proposed. The rate constant for this chemical reaction under pseudo-first-order conditions, evaluated using working curves, was employed in the simulation of the voltammetric response. The second-order rate constant was also evaluated. Influences of the reaction at ?0.800 V on enzymatic electrodes employing nitrate reductase (NR) and MV⁺ as mediator were also analysed by chronoamperometry.     

Nitrite Reduces Acute Lung Injury and Improves Survival in a Rat Lung Transplantation Model

Ischemia/reperfusion injury (IRI) is the most common cause of early mortality following lung transplantation (LTx). We hypothesized that nitrite, an endogenous source of nitric oxide (NO), may protect lung grafts from IRI. Rat lung grafts were stored in preservation solution at 4°C for 6 hours. Both grafts and recipients were treated with nitrite. Nitrite treatment was associated with significantly higher levels of tissue oxygenation, lower levels of cytokines and neutrophil/macrophage infiltration, lower myeloperoxidase activity, reduced oxidative injury and increased cGMP levels in grafts than in the controls. Treatment with either a nitric oxide scavenger or a soluble guanylyl cyclase (sGC) inhibitor diminished the beneficial effects of nitrite and decreased cGMP concentrations. These results suggest that nitric oxide, generated from nitrite, is the molecule responsible for the effects of nitrite via the nitric oxide/sGC/cGMP pathway. Allopurinol, a xanthine oxidoreductase (XOR) inhibitor, abrogated the protective effects of nitrite, suggesting that XOR is a key enzyme in the conversion of nitrite to nitric oxide. In vitro experiments demonstrated that nitrite prevented apoptosis in pulmonary endothelial cells. Nitrite also exhibits longer survival rate in recipients than control. In conclusion, nitrite inhibits lung IRI following cold preservation and had higher survival rate in LTx model.     

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.     

亚硝酸钠和克山病病区粮对大鼠心肌线粒体四种复合物活性的影响

本研究观察了亚硝酸钠和克山病病区粮对大白鼠心肌线粒体呼吸链四种复合物活性的影响。发现克山病病区粮可使复合物Ⅰ、Ⅱ和Ⅳ活性下降,而亚硝酸钠也可降低复合物Ⅰ和Ⅳ的活性。结果表明,亚硝酸盐和克山病病区粮在对心肌能量代谢影响方面的一致性很可能是它们在形态学上所呈现出来的协同作用的原因之一。本文还对亚硝酸盐影响线粒体复合物活性的机制进行了讨论。     

一起就餐后引起胃部不适症状投诉的调查及分析

目的 对一起就餐后引起胃部不适症状的投诉进行调查及分析. 方法 亚硝酸盐依据GB5009.33-2010进行检测,菌落总数、沙门菌、金黄色葡萄球菌依据GB4789.2,4,10-2010进行检测,大肠菌群、志贺菌依据GB4789.3,5-2003进行检测. 亚硝酸盐依据GB2760-2011《食品添加剂使用标准》进行判定. 结果 患者呕吐物亚硝酸盐含量为7.90 mg/kg,筒子骨炖萝卜样品中亚硝酸盐含量为29.84 mg/kg.样品中未检出致病菌.结论少量亚硝酸盐引起的轻度食物中毒症状不明显,容易出现误诊,要进一步加强对亚硝酸盐使用的监管.