再生障碍性贫血患者血清一氧化氮与细胞因子水平分析

生物体内的一氧化氮 (NO)作为一种反应极强的效应分子 ,不仅参与免疫调控 ,而且也是造血祖细胞生长和分化不可缺少的调节因子 [1 ]。本文通过对再生障碍性贫血 (AA)患者血清 NO与白细胞介素 - 2 (IL- 2 )、肿瘤坏死子 (TNF)、血小板生成素 (TPO)、红细胞生成素 (EPO)、GM- CSF、5种细胞因子水平测定 ,分析其与外周血象及各细胞因子间的相互关系 ,并探讨 NO及 IL- 2等细胞因子在 AA发生发展过程中的作用。1　材料和方法1.1　材料1.1.1　标本来源　 AA患者 5 0例 ,以 2 0 0 2年 3月至 2 0 0 4年4月我院确诊为 AA的患者为研究对象…     

Handling of asymmetrical dimethylarginine and symmetrical dimethylarginine by the rat kidney under basal conditions and during endotoxaemia.

BACKGROUND: Asymmetrical dimethylarginine (ADMA) is capable of inhibiting nitric oxide synthase enzymes, whereas symmetrical dimethylarginine (SDMA) competes with arginine transport. The potential role of inflammation in the metabolism of ADMA has been elucidated in an in vitro model using tumour necrosis factor-alpha, resulting in a decreased activity of the ADMA-degrading enzyme dimethylarginine dimethylaminohydrolase (DDAH). The kidney probably plays a crucial role in the metabolism of ADMA by both urinary excretion and degradation by DDAH. We aimed to further elucidate the role of the kidney in a rat model under basal conditions and during endotoxaemia. METHODS: Twenty-five male Wistar rats weighing 275-300 g were used for this study. The combination of arteriovenous concentration differences and kidney blood flow allowed calculation of net organ fluxes. Blood flow was measured using radiolabelled microspheres according to the reference sample method. Concentrations of ADMA, SDMA and arginine were measured by high-performance liquid chromatography. RESULTS: The kidney showed net uptake of both ADMA and SDMA and fractional extraction rates were 35% and 31%, respectively. Endotoxaemia resulted in a lower systemic ADMA concentration (P = 0.01), which was not explained by an increased net renal uptake. Systemic SDMA concentrations increased during endotoxaemia (P = 0.007), which was accompanied by increased creatinine concentrations. CONCLUSIONS: The rat kidney plays a crucial role in the regulation of concentrations of dimethylarginines, as both ADMA and SDMA were eliminated from the systemic circulation in substantial amounts. Furthermore, evidence for the role of endotoxaemia in the metabolism of dimethylarginines was obtained as plasma levels of ADMA were significantly lower in endotoxaemic rats.     

一氧化氮与胚胎异常发育的相关性研究

为了解开一氧化氮（ＮＯ）是否与畸胎发生有关这一谜团和进一步阐明砷致畸作用机理，本实验应用诱生型ＮＯ合成酶（ｉＮＯＳ）组织化学、扫描电镜（ＳＥＭ）及体内致畸试验等方法研究了砷对小鼠卵黄囊胎盘（ＹＳＰ）和胚胎发育的影响。结果表明ＹＳＰ细胞ｉＮＯＳ表达与砷浓度之间存在明显的剂量—反应关系（Ｐ＜０．０５）；ＳＥＭ观察可见ＹＳＰ内皮层和间皮层细胞受损；光镜下可见ＹＳＰ变小、萎缩和微血管分化不良；随着染毒剂量的升高，畸胎率和死胎率亦逐步增加，最高分别达到５６．８％和２４．７％；畸胎的主要表现是神经管未闭，心包积液和体位异常等。研究结果率先提示过量ＮＯ与畸胎发生及致畸机理关系密切；推荐在致畸研究中ｉＮＯＳ可作为一种有效的生物标志物。     

几种化合物对石棉诱发肺泡巨噬细胞产生一氧化氮的抑制作用

为了寻求一种适宜的石棉表面改性剂，利用体外细胞培养技术，通过测定培养液中亚硝酸根（ＮＯ－２）含量，观察了茫崖产温石棉对豚鼠肺泡巨噬细胞（ＡＭ）产生一氧化氮（ＮＯ）的诱导作用以及混合稀土、亚硒酸钠、柠檬酸铝对石棉诱发ＡＭ产生ＮＯ的影响。结果显示，温石棉纤维可使培养液中ＮＯ－２浓度升高，并呈明显的剂量反应关系；混合稀土、亚硒酸钠、柠檬酸铝均可抑制石棉诱发ＡＭ产生ＮＯ，而且随上述化合物浓度的升高，抑制作用增强。提示用混合稀土和亚硒酸钠拮抗石棉的致病作用有实际应用的可能。     

内毒素休克大鼠核因子κB活化规律及其在生物蝶呤诱生中的作用

目的观察内毒素休克大鼠血浆及主要脏器核因子(NF)κB活化规律及其对生物蝶呤(BH4)和一氧化氮(NO)表达水平的影响,探讨内毒素休克时NF-κB信号通路对BH4诱生NO的分子调控机制及其与多器官功能损害的关系。方法将47只大鼠按表格随机法分为正常组(8只)、内毒素／脂多糖(LPS)组(24只,每观察时相点8只,均同时注射LPS制成休克模型)和拮抗组[15只,每观察时相点5只,均同时注射LPS并以吡咯烷二硫代氨基甲酸盐(PDTC)拮抗]。休克及拮抗组于注射LPS后2、6、12 h观察,并与正常组同法处死,无菌留取大鼠血标本及肝、肺、肾组织,测定组织中NF-κB活性和三磷酸鸟苷环水解酶Ⅰ(GTP-CHⅠ)和诱导型一氧化氮合酶(iNOS)mRNA表达水平、血浆和组织中的BH4含量及NO水平、肝脏和肾脏功能指标、肺组织髓过氧化物酶活性。结果与正常组(例如肺组织中NF-κB活性为26±6)比较,LPS组大鼠组织中NF-κB迅速活化(P<0．01),并于注射后2 h达峰值(肺组织中为291±44);LPS组各组织中GTP-CHⅠ和iNOS mRNA表达、BH4和NO水平也较正常组明显升高(P<0．05或0．01),至伤后12 h仍持续较高水平。此外,该组相应器官功能均受到不同程度的损害。应用PDTC的拮抗组大鼠各组织中NF-κB活性均较LPS组有所降低,GTP-CHⅠ、iNOS mRNA表达及BH4、NO水平显著受抑,肝、肺、肾功能明显改善。结论内毒素休克时机体内NF-κB通路高度活化,并对BH4／NO系统具有明显调节效应;可通过下调BH4介导的iNOS的过度活化抑制NF-κB信号途径,从而减轻组织炎性反应,对机体脏器功能起到保护作用。     

良性前列腺增生组织中一氧化氮合酶活性的变化

为探讨一氧化氮（ＮＯ）与良性前列腺增生（ＢＰＨ）发病的关系，应用双波长分光光度法测定１５例正常前列腺及２５例ＢＰＨ组织中一氧化氮合酶（ＮＯＳ）活性，并比较不同年龄组的正常前列腺及ＢＰＨ组织中ＮＯＳ活性水平。结果：ＢＰＨ组织中ＮＯＳ活性（９６．７７±２８．０２ｐｍｏｌ．ｍｇ－１．ｍｉｎ－１）明显低于正常前列腺者（２９０．９９±１３０．６８ｐｍｏｌ．ｍｇ－１．ｍｉｎ－１），Ｐ＜０．００１。不同年龄组的正常前列腺组织中ＮＯＳ活性水平与年龄无相关关系。而在５０岁、６０岁和≥７０岁三个年龄组之间的ＢＰＨ组织中ＮＯＳ活性水平有显著性差异，Ｐ＜０．０１，ＢＰＨ组织中ＮＯＳ活性水平随年龄增大呈下降趋势。结果提示前列腺组织中ＮＯＳ活性水平与ＢＰＨ有相关关系，ＮＯＳ活性降低可能是ＢＰＨ的年龄依赖性发病原因之一。     

Inhibition of nitric oxide synthase attenuates blood-brain barrier disruption during experimental meningitis

Increased permeability of the blood-brain (B-B) barrier is observed during meningitis. Preventing B-B barrier alterations is important because adverse neurological outcomes are correlated with breeches in barrier integrity. It was hypothesized that pathological production of nitric oxide (NO) contributes to B-B barrier disruption during meningitis in the rat. Experimental meningitis was induced by intracisternal (i.c.) administration of lipopolysaccharides (LPS) or vehicle. Groups of rats were concomitantly infused intravenously (i.v.) with saline or the NO synthase inhibitor, aminoguanidine (AG). Eight h after i.c. dosing, B-B barrier alterations were quantitated pharmacokinetically using [¹⁴C]sucrose. Serum and regional brain tissues were obtained 0–30 min after tracer dosing and sucrose influx transfer coefficients ( K_{in (app)}) were calculated from the brain tissue data. Compared to the control groups (i.c. vehicle/i.v. saline), the K_{in (app)} of the i.c. LPS/i.v. saline group increased 1.6–2.1-fold in various brain regions, thus confirming previous observations of increased [¹⁴C]sucrose barrier penetration during meningeal inflammation. Remarkably, i.v. administration of AG to i.c. LPS-treated rats significantly inhibited meningeal NO synthesis and decreased K_{in (app)} permeability alterations in the B-B barrier, compared to i.c. LPS/i.v. saline-treated rats. Regional brain K_{in (app)} estimates in the i.c. LPS/i.v. AG group were similar to control groups (i.c. vehicle/i.v. AG and i.c. vehicle/i.v. saline). In conclusion, these data suggest the general concept that excessive NO production during neuroinflammatory diseases contributes to disruption of the blood-brain barrier.     

Nitric oxide synthesis in endothelial cytosol: Evidence for a calcium-dependent and a calcium-independent mechanism

Summary Release of nitric oxide (NO) from endothelial cells critically depends on a sustained increase in intracellular free calcium maintained by a transmembrane calcium influx into the cells. Therefore, we studied whether the free cytosolic calcium concentration directly affects the activity of the NO-forming enzyme(s) present in the cytosol from freshly harvested porcine aortic endothelial cells. NO was quantified by activation of a purified soluble guanylate cyclase coincubated with the cytosol. In the presence of 1 mM L-arginine, 0.1 mM NADPH and 0.1 mM EGTA, endothelial cytosol (0.2 mg of cytosolic protein per ml) stimulated the activity of guanylate cyclase 5.0 + 0.5-fold (from 31 + 9 to 153 + 15 nmol cyclic GMP formed per min per mg guanylate cyclase). Calcium chloride increased this stimulation further in a concentration-dependent fashion by up to 136 + 15% (with 2 M free calcium; EC₅₀ 0.3 M). The calcium-dependent and -independent activation of guanylate cyclase was enhanced by superoxide dismutase (0.3 M) and was inhibited by the stereospecifically acting inhibitor of L-arginine-dependent NO formation N^G-nitro-L-arginine (1 mM) and by LY 83583 (1 M), a generator of superoxide anions. Our findings suggest a calcium-dependent and -independent synthesis of NO from L-arginine by native porcine aortic endothelial cells. Send of fprint requests to A. Mülsch, at the above address     

Effects of atrial natriuretic peptide on DNA synthesis and NADPH diaphorase activity in epitheliocytes and smooth muscle cells of the respiratory tract in newborn albino rats

Newborn rats received single intraperitoneal injections of atrial natriuretic peptide (1-28) in a dose of 3.2×10_-8 mol/kg on day 6 of life. Autoradiography with ³H-thymidine showed that the peptide inhibited DNA synthesis in smooth muscle cells of the respiratory tract. Pretreatment with nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester attenuated, but did not abolish the effect of atrial natriuretic peptide (1-28). Histochemical assay for NADPH diaphorase showed that nitric oxide constitutively produced in the epithelium is involved in the growth-inhibitory effect of atrial natriuretic peptide (1-28) on proliferating smooth muscle cells.     

Role of nitric oxide in skeletal muscle: synthesis,distribution and functional importance

Over the last two decades, nitric oxide (NO) has been established as a novel mediator of biological processes, ranging from vascular control to long-term memory, from tissue inflammation to penile erection. This paper reviews recent research which shows that NO and its derivatives also are synthesized within skeletal muscle and that NO derivatives influence various aspects of muscle function. Individual muscle fibres express one or both of the constitutive NO synthase (NOS) isoforms. Type I (neuronal) NOS is localized to the sarcolemma of fast fibres; type III (endothelial) NOS is associated with mitochondria. Isolated skeletal muscle produces NO at low rates under resting conditions and at higher rates during repetitive contraction. NO appears to mediate cell–cell interactions in muscle, including vasodilation and inhibition of leucocyte adhesion. NO also acts directly on muscle fibres to alter cell function. Muscle metabolism appears to be NO-sensitive at several sites, including glucose uptake, glycolysis, mitochondrial oxygen consumption and creatine kinase activity. NO also modulates muscle contraction, inhibiting force output by altering excitation–contraction coupling. The mechanisms of NO action are likely to include direct effects on redox-sensitive regulatory proteins, interaction with endogenous reactive oxygen species, and activation of second messengers such as cyclic guanosine monophosphate (cGMP). In conclusion, research published over the past few years makes it clear that skeletal muscle produces NO and that endogenous NO modulates muscle function. Much remains to be learned, however, about the physiological importance of NO actions and about their underlying mechanisms.