The vascular endothelium masks the persistent inhibition of rat thoracic arterial tone induced by S-nitrosoglutathione

Aim

In endothelium-denuded arteries, the nitric oxide (NO) donor S-nitrosoglutathione (GSNO) induced a persistent hypo-reactivity to vasoconstrictors, and low-molecular weight thiols such as N-acetyl cysteine (NAC) produced a relaxant effect. These effects were attributed to the formation of vascular NO stores. In arteries with a functional endothelium, such long-lasting effects on arterial tone have not been well characterised. In this study, we proposed to examine the possibility of storing exogenous NO when the vascular endothelium is still able to produce its own NO.

Methods

For this purpose, changes in isometric tension of isolated arteries were assessed in organ chambers, and nitrosothiol formation was characterised by confocal microscopy.

Results

In rat aortic rings with endothelium pre-exposed to GSNO, the contractile response to norepinephrine (NE) was not attenuated in comparison with control rings, but NAC induced a relaxant effect. However, an attenuation of the response to NE was observed in GSNO-exposed, intact aortic rings after inhibition of NO synthase by N^w-nitro-L-arginine methylester (L-NAME) or in GSNO-denuded rings.The relaxing effects of NAC were due to the mobilisation of NO from nitrosothiols after nitrosylation of protein SH residues. Moreover, the hypo-reactivity to NE and the relaxant effect of NAC were abolished by 1H-[1,2,4] oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, and partially by the K⁺-sensitive channel inhibitor tetra-ethyl-ammonium (TEA).

Conclusion

These data show that endothelium-derived NO masked the persistent effect of GSNO in rat thoracic aorta. However, the ability of GSNO to form releasable NO stores without altering the vascular tone can be particularly useful in preventing endothelial dysfunction in which NO formation decreases.     

N-Nitrosomelatonin: synthesis, chemical properties, potential prodrug

Abstract:  Melatonin is easily nitrosated via various mechanisms at the nitrogen atom of the indole ring to give N -nitrosomelatonin (NOMela). This Mini-review provides a comprehensive view of this N -nitroso compound. With an improved procedure NOMela can now economically synthesized with low laboratory expenditure. The major chemical property of NOMela, i.e. the (formally) transfer of the NO⁺ function to its target nucleophile, is explained in detail and a variety of detection methods using this reaction are suggested. As the suspected carcinogenical potential of NOMela is clearly overruled it seems attractive to apply this nitroso compound for endogenous generation of S -nitrosothiols that act as nitric oxide donors in vivo.     

First insights into regiospecific transnitrosation reactions between tryptophan derivatives: melatonin as an effective target

Melatonin, a derivative of the essential amino acid tryptophan, has been portrayed as a hormone, a tissue factor, an autocoid, a paracoid, and a vitamin with antioxidative capabilities. In the present study a novel reaction which cannot be attributed to any of these suggested features, i.e. the transfer of the nitroso-function from N-nitrosotryptophan derivatives to melatonin, is unequivocally demonstrated. In the lipophilic buffer dimethylsulfoxide reaction of N-acetyl-N-nitrosotryptophan (NANT) with melatonin was very slow (k = 1.5 x 10(-6)/m/s), but reversible as shown by 15N-NMR spectrometry. These measurements demonstrated also that the thermodynamical equilibrium lies on the side of N-nitrosomelatonin (NOMela). Quantum-chemical calculations performed with the third-generation density functional B97-2 additionally predicted that this is also the case in an aqueous environment. In fact, reaction of melatonin with either NANT or N-nitrosotryptophan located at the endothelin-1 fragment 16-21 yielded NOMela with a rate constant of 1.7 +/- 0.5/m/s as shown by capillary zone electrophoresis. Interestingly, the known reactive nitrogen oxide species scavenger, piperazine, did not inhibit the NANT-dependent nitrosation of melatonin, thus very strongly indicating a direct transnitrosation reaction. All of these capabilities are known from the reaction of S-nitrosothiols with thiolate anions and are believed to be highly important in the transport and targeting of nitric oxide.     

Antibodies directed against nitrosylated neoepitopes in sera of patients with human African trypanosomiasis

Antibodies directed against nitrosylated epitopes have been found in sera from patients suffering from human African trypanosomiasis (HAT) but not in sera from control subjects living in the same endemic area or African control subjects living in France. We conjugated amino acids to albumin by glutaraldehyde (conjugates) and then nitrosylated the conjugates. Both conjugates and nitrosylated conjugates were analysed by enzyme-linked immunosorbent assay (ELISA). We detected antibodies directed against nitrosylated L-cysteine and L-tyrosine conjugates; antibody levels were higher in stage II patients than in stage I. Patients with severe clinical signs had higher antibody levels, and antibody levels were highest in patients with major neurological signs. Antibody response was only associated with the IgM isotype. We evaluated antibody specificity and avidity by competition experiments using conjugates and nitrosylated conjugates. Avidity was around 2 x10(-6) m for the S-nitroso-cysteine epitope and 2 x 10(-8) m for the S-nitroso-tyrosine epitope. Detection of circulating antibodies to S-nitroso-cysteine and S-nitroso-tyrosine epitopes provides indirect evidence for nitric oxide (NO) involvement in HAT and their levels are correlated with disease severity.     

Pharmacological assessment of the role of nitric oxide in mice infected with lethal and nonlethal species of malaria

This pharmacological investigation sought to determine whether nitric oxide (NO) had an antiparasitic effect and/or mediated pathology in mice infected with nonlethal P. chabaudi or lethal P. berghei. Nitric oxide synthase (NOS) inhibitors were evaluated for their ability to inhibit the rise in reactive nitrogen intermediates (RNI) induced by bacterial lipopolysaccharide (LPS) in mice. The more effective compound, aminoguanidine (AG) inhibited the rise in RNI induced by P. chabaudi and increased mortality, but had no effect on parasitaemia. Inducers and donors of NO were screened for their ability to increase RNI and the most effective agents evaluated for their ability to modify P. berghei infection. S-Nitrosoglutathione had little effect, but LPS decreased parasitaemia and mortality. An inconsistent relationship is evident between the abilities of these agents to modify NO activity and their effects on malaria in mice. Increased mortality in mice with P. chabaudi treated with AG indicates a reduction in resistance. The absence of an effect on parasitaemia by a NOS inhibitor or NO donor indicates either RNI have insignificant antimalarial action in vivo or the efficacy of the compounds is inadequade. Resistance to P. berghei in LPS-treated mice demonstrates an antiparasitic effect, but this may be attributable to factors other than NO.     

血浆同型半胱氨酸与冠心病及高血压的相关性研究

目的探讨冠心病及高血压患者中,血浆同型半胱氨酸、一氧化氮水平的变化。方法对99例冠心病患者(冠心病组)与122例单纯高血压患者(高血压组)进行血浆同型半胱氨酸、一氧化氮水平的测定。结果冠心病组血浆同型半胱氨酸浓度为(18.57±7.47)μmol/L,明显高于高血压组(14.53±10.58)μmol/L(P0.01)。冠心病组血清一氧化氮浓度为(51.15±18.78)μmol/L,明显低于高血压组(70.39±41.55)μmol/L(P0.001)。结论高同型半胱氨酸血症与冠心病的发生有密切关系,并且同型半胱氨酸水平与一氧化氮呈反比,可能同型半胱氨酸水平与血管损伤的严重程度有明显的相关性。     

Cardioprotective effects of thioredoxin in myocardial ischemia and reperfusion: role of S-nitrosation [corrected

Apoptosis contributes to myocardial ischemia/reperfusion (MI/R) injury, and both thioredoxin (Trx) and nitric oxide have been shown to exert antiapoptotic effects in vitro. Recent evidence suggests that this particular action of Trx requires S-nitrosation at Cys-69. The present study sought to investigate whether or not exogenously applied Trx reduces MI/R injury in vivo and to which extent this effect depends on S-nitrosation. Adult mice were subjected to 30 min of MI and treated with either vehicle or human Trx (hTrx, 2 mg/kg, i.p.) 10 min before reperfusion. Native hTrx was incorporated into myocardial tissue as shown by immunostaining, and reduced MI/R injury as evidenced by decreased terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, DNA fragmentation, caspase-3 activity, and infarct size. When hTrx was partially S-nitrosated by preincubation with S-nitrosoglutathione, its cardioprotective effect was markedly enhanced. Treatment with hTrx significantly reduced p38 mitogen-activated protein kinase (MAPK) activity, and this effect was also potentiated by S-nitrosation. To further address the role of S-nitrosation for the overall antiapoptotic effect to Trx, the action of Escherichia coli Trx (eTrx) was investigated in the same model. Whereas eTrx inhibited MI/R-induced apoptosis to a degree similar to hTrx, S-nitrosation of this protein, which lacks Cys-69, failed to further enhance its antiapoptotic action. Collectively, our results demonstrate that systemically applied Trx is taken up by the myocardium to exert potent cardioprotective effects in vivo, offering interesting therapeutic avenues. In the case of hTrx, these effects are further potentiated by S-nitrosation, but this posttranslational modification is not essential for protection.     

The mitochondrial thioredoxin reductase system (TrxR2) in vascular endothelium controls peroxynitrite levels and tissue integrity

The mitochondrial thioredoxin/peroxiredoxin system encompasses NADPH, thioredoxin reductase 2 (TrxR2), thioredoxin 2, and peroxiredoxins 3 and 5 (Prx3 and Prx5) and is crucial to regulate cell redox homeostasis via the efficient catabolism of peroxides (TrxR2 and Trxrd2 refer to the mitochondrial thioredoxin reductase protein and gene, respectively). Here, we report that endothelial TrxR2 controls both the steady-state concentration of peroxynitrite, the product of the reaction of superoxide radical and nitric oxide, and the integrity of the vascular system. Mice with endothelial deletion of the Trxrd2 gene develop increased vascular stiffness and hypertrophy of the vascular wall. Furthermore, they suffer from renal abnormalities, including thickening of the Bowman’s capsule, glomerulosclerosis, and functional alterations. Mechanistically, we show that loss of Trxrd2 results in enhanced peroxynitrite steady-state levels in both vascular endothelial cells and vessels by using a highly sensitive redox probe, fluorescein-boronate. High steady-state peroxynitrite levels were further found to coincide with elevated protein tyrosine nitration in renal tissue and a substantial change of the redox state of Prx3 toward the oxidized protein, even though glutaredoxin 2 (Grx2) expression increased in parallel. Additional studies using a mitochondria-specific fluorescence probe (MitoPY1) in vessels revealed that enhanced peroxynitrite levels are indeed generated in mitochondria. Treatment with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin [Mn(III)TMPyP], a peroxynitrite-decomposition catalyst, blunted intravascular formation of peroxynitrite. Our data provide compelling evidence for a yet-unrecognized role of TrxR2 in balancing the nitric oxide/peroxynitrite ratio in endothelial cells in vivo and thus establish a link between enhanced mitochondrial peroxynitrite and disruption of vascular integrity.

Selenocysteine-containing mitochondrial thioredoxin reductase (TrxR2) is the key regulator of the thioredoxin system and essential for mitochondrial redox homeostasis (1–3). This system constitutes a primary defense against peroxides produced in mitochondria, such as hydrogen peroxide and peroxynitrite (4). TrxR2 is necessary for maintaining thioredoxin 2 (Trx2) in its reduced state by using electrons from NADPH. In turn, Trx2 is a cofactor of mitochondrially localized peroxiredoxin 3 (Prx3) and peroxiredoxin 5 (Prx5) that reduce H₂O₂ and peroxynitrite^* generated by mitochondrial metabolism (1, 2, 4–7). The reaction rate constants of H₂O₂ and peroxynitrite with the fast reacting thiols of both Prx3 and Prx5 have been compiled recently (4). Notably, Prx3, the only peroxiredoxin which is exclusively localized in mitochondria (8, 9)^†, was reported to accept electrons also from glutaredoxin 2 (Grx2) (10). Among the biologically recognized functions, TrxR2 plays essential roles in hematopoiesis, heart development, and heart function (11, 12). In a previous study, we could show that loss of TrxR2 in endothelial cells (ECs) attenuated vascular remodeling processes following ischemic events and led to a prothrombotic and proinflammatory endothelium (13). While these studies pointed toward an important role of TrxR2 in the cardiovascular system, the underlying biochemical mechanisms, particularly in vivo, have remained largely unclear. Unlike many other cell types in the body, ECs are unique as they are constantly exposed to changing biochemical and mechanical stimuli. Furthermore, they do not just separate the circulating blood and the vascular smooth muscle cells but also have to fulfill a wide range of physiological tasks, including regulation of vascular tone, cellular adhesion, thromboresistance, smooth muscle cell proliferation, and inflammoresistance (14, 15). One of the most significant biomolecules that is involved in vascular endothelial function is the free radical nitric oxide (·NO) (16, 17). ·NO is not only an important vasodilator but also has antiinflammatory properties by inhibiting the synthesis and expression of cytokines and adhesion molecules that attract inflammatory cells and facilitate their entrance into the vessel wall (18, 19). Furthermore, ·NO suppresses platelet aggregation (20), vascular smooth muscle cell migration, and proliferation (21). Consequentially, a decreased synthesis of ·NO, as well as an enhanced inactivation, can result in endothelial dysfunction (22–24). Oxidative stress contributes to this phenomenon, starting with the diffusion-controlled reaction of ·NO with superoxide radical (O₂^·−), which shortens the biological half-life and compromises the signaling actions of ·NO (25–28). In addition, the oxidative inactivation of ·NO by O₂^·− yields a powerful oxidizing and nitrating species, peroxynitrite anion (28, 29). Moreover, peroxynitrite itself leads to uncoupling of endothelial nitric oxide synthase to become a dysfunctional O₂^·− and peroxynitrite-producing enzyme that additionally contributes to cellular oxidative stress (30, 31). A sustained overload of O₂^·− and, peroxynitrite combined with insufficient levels of ·NO may contribute to a switch of the endothelium from the quiescent stage toward an activated one, setting up a vicious cycle, causing endothelial dysfunction and inflammation. ECs are equipped with a number of antioxidant systems known to be potentially protective against vascular oxidative stress that, however, under persistent pathological stimuli, may become overwhelmed.In this context, it is increasingly recognized that mitochondrial-derived O₂^·− and the disruption of mitochondrial redox homeostasis contribute to alter the signaling actions of ·NO in vascular biology (32–34). Besides the mitochondrial thioredoxin system, a number of professional redox systems, including mitochondrial superoxide dismutase (MnSOD/SOD2), glutathione peroxidase, and glutathione reductase, are involved in maintaining mitochondrial redox homeostasis.However, the specific roles of these enzymes in the context of endothelial dysfunction are far from being understood. The fact that genetically modified mouse models revealed that many of the different antioxidant enzymes are indispensable for murine development (35–38) impedes further insights into their role for vascular homeostasis, and, to our knowledge, only a limited number of EC-specific transgenic mice have yet been described in this context (39–42). Interestingly, Trx2 transgenic mice that overexpress Trx2 specifically in the endothelium demonstrated an increased ·NO bioavailability and EC function, decreased oxidative stress, and reduced propensity to atheroma formation (3, 43).The aim of this study was to analyze the impact of endothelial TrxR2 on vascular homeostasis (in vitro, ex vivo, and in vivo), focusing on its role on mitochondrial peroxynitrite catabolism. The data support that enhanced mitochondrial steady-state levels of peroxynitrite in vascular ECs are connected with disruption of redox homeostasis and vascular structural and functional integrity.     

Structural profiling of endogenous S-nitrosocysteine residues reveals unique features that accommodate diverse mechanisms for protein S-nitrosylation

S-nitrosylation, the selective posttranslational modification of protein cysteine residues to form S-nitrosocysteine, is one of the molecular mechanisms by which nitric oxide influences diverse biological functions. In this study, unique MS-based proteomic approaches precisely pinpointed the site of S-nitrosylation in 328 peptides in 192 proteins endogenously modified in WT mouse liver. Structural analyses revealed that S-nitrosylated cysteine residues were equally distributed in hydrophobic and hydrophilic areas of proteins with an average predicted pK_a of 10.01 ± 2.1. S-nitrosylation sites were over-represented in α-helices and under-represented in coils as compared with unmodified cysteine residues in the same proteins (χ² test, P < 0.02). A quantile–quantile probability plot indicated that the distribution of S-nitrosocysteine residues was skewed toward larger surface accessible areas compared with the unmodified cysteine residues in the same proteins. Seventy percent of the S-nitrosylated cysteine residues were surrounded by negatively or positively charged amino acids within a 6-Å distance. The location of cysteine residues in α-helices and coils in highly accessible surfaces bordered by charged amino acids implies site directed S-nitrosylation mediated by protein–protein or small molecule interactions. Moreover, 13 modified cysteine residues were coordinated with metals and 15 metalloproteins were endogenously modified supporting metal-catalyzed S-nitrosylation mechanisms. Collectively, the endogenous S-nitrosoproteome in the liver has structural features that accommodate multiple mechanisms for selective site-directed S-nitrosylation.     

胱抑素C水平与冠心病的相关性研究

目的了解胱抑素C水平与冠状动脉病变严重程度的关系。方法选择疑诊冠心病且行选择性冠状动脉造影的冠心病患者114例(冠心病组).根据临床病史和冠状动脉造影结果分为2组:急性冠状动脉综合征(acute coronarysyndromes,ACS)组73例,稳定性心绞痛(stable angina pectoris,SAP)组41例;另选择非冠心病(冠状动脉造影阴性)患者38例作为对照组。采用Gensini评分系统对冠状动脉病变程度进行评分。应用免疫比浊法测定血清胱抑素C水平。分析血清胱抑素C水平与冠状动脉病变严重程度及病变支数的相互关系。结果 ACS组和SAP组血清胱抑素C水平明显高于对照组[(2.2±3.5)mg/L vs(1.6±4.1)mg/L vs(0.7±2.9)mg/L,P<0.01].且ACS组血清胱抑素C水平明显高于SAP组(P<0.05)。Gcnsini积分≥30分患者血清胱抑素C水平明显高于Gensini积分<30分患者[(2.6±2.7)mg/L vs(1.8±5.2)mg/L,P<0.01]。3支病变患者血清胱抑紊C水平和Gensini积分较单支病变和双支病变患者明显增高[(2.8±1.8)mg/L vs(1.9±3.4)mg/L vs(2.1±4.1)mg/L;(49±16)分v5(17±9)分vs(28±1 8)分,P<0.05,P<0.01];双支病变患者Gensin积分较单支病变患者明显增高(P<0.01);而单支病变与双支病变患者血清胱抑素C水平差异无统计学意义(P>0.05)。血清胱抑素C水平与冠状动脉病变严重程度Gensini积分呈正相关(r=0.673,P<0.01)。结论胱抑素C水平与冠状动脉病变严重程度及病变支数显著相关,胱抑素C水平可以作为评价冠状动脉病变严重程度的一个指标。     

A protein microarray-based analysis of S-nitrosylation

The ubiquitous cellular influence of nitric oxide (NO) is exerted substantially through protein S-nitrosylation. Whereas NO is highly promiscuous, physiological S-nitrosylation is typically restricted to one or very few Cys residue(s) in target proteins. The molecular basis for this specificity may derive from properties of the target protein, the S-nitrosylating species, or both. Here, we describe a protein microarray-based approach to investigate determinants of S-nitrosylation by biologically relevant low-mass S-nitrosothiols (SNOs). We identify large sets of yeast and human target proteins, among which those with active-site Cys thiols residing at N termini of α-helices or within catalytic loops were particularly prominent. However, S-nitrosylation varied substantially even within these families of proteins (e.g., papain-related Cys-dependent hydrolases and rhodanese/Cdc25 phosphatases), suggesting that neither secondary structure nor intrinsic nucleophilicity of Cys thiols was sufficient to explain specificity. Further analyses revealed a substantial influence of NO-donor stereochemistry and structure on efficiency of S-nitrosylation as well as an unanticipated and important role for allosteric effectors. Thus, high-throughput screening and unbiased proteome coverage reveal multifactorial determinants of S-nitrosylation (which may be overlooked in alternative proteomic analyses), and support the idea that target specificity can be achieved through rational design of S-nitrosothiols.     

The impact of estrogen and L-arginine on serum NO and eNOS expression in aorta of aged rats

Background Cardiovascular diseases (CVD) are less prevalent in postmenopausal women received estrogen replacement therapy (ERT) than those who did not receive ERT.Previous study has shown that the increase of nitric oxide (NO) synthesis is one of the cardioprotective effects of estrogen.This study investigated the effects of estrogen and L-arginine (L-Arg) on serum NO concentrations and the possible regulatory role in endothelial nitric oxide synthase (eNOS) expression in aortas of aged rats.Methods Fifty aged female wistar rats (18-20 months) were randomly divided into five groups (n=10):Sham group (sham operated,0.9 % NaCl 10 μg every three day for 4 months),OVX group (ovariectomized,0.9 % NaCl 10 μg i.m every three day for 4 months),OVE group (ovariectomized + 17β-estradiol 10 μg i.m every three day for 4 months),OVE + L-Arg group (ovariectomized + 17β-estradiol 10ug i.m every three day + 2.25 % L-Arg contained in drinking water every day for 4 months) and L-Arg group (ovariectomized + 2.25 % L-Arg contained in drinking water every day for 4 months).NO concentration and the expression of eNOS mRNA in aorta were measured after 4 months.Results Serum NO synthesis did not alter after ovariectomized (P=0.362),but were increased in OVE group,L-Arg group and OVE + L-Arg group compared with OVX group (P < 0.05,P < 0.05,P < 0.01,respectively).NO concentration also increased in OVE + L-Arg group when compared with OVE group (P < 0.05) or L-Arg group (P < 0.05).There was no significant difference in eNOS mRNA expression in aortas of aged rats between sham,OVX,OVE,OVE + L-Arg and L-Arg group (F=0.550,P=0.700).Conclusions Estrogen treatment and L-Arg supplementation increase serum NO synthesis,but do not upregulate eNOS mRNA expression in aortas of aged rats.     

内皮型一氧化氮合酶基因G894T多态性与原发性高血压的相关关系

目的　探讨内皮型一氧化氮合酶 (eNOS)基因G894T多态性与中国汉族人原发性高血压 (EH)的相关性。方法　 (1)采用多聚酶链式反应结合限制性内切酶片段长度多态分析方法检测310例健康人和 15 1例高血压患者的eNOS基因G894T多态性 ,(2 )硝酸还原酶法测定空腹血清一氧化氮代谢物 (NOx)水平 ,用放射免疫法测定内皮素 (ET)的水平。结果　 (1)EH组GT TT基因型和T等位基因频率显著高于对照组 (P <0 0 5 ) ;(2 )高血压患者中T等位基因携带者的收缩压 [(15 0 5± 13 6 )mmHg]、舒张压 [(10 0 0± 8 5 )mmHg]和脉压 (116 8± 7 8)mmHg均高于GG基因型携带者 (14 5 0± 12 2 ,97 4± 8 0 ,114 0± 7 5 )mmHg ,且有显著性差异 ,(P <0 0 5 )。 (3)EH组GT TT基因型空腹血清NOx[(6 9 7± 2 7 0 ) μmol/L]、NOx/ET比 (1 0 1± 0 5 6 )明显低于GG基因型 (78 5± 32 5 ) μmol/L (1 4 7± 1 5 1) ,而GT TT基因型 (83 2 5± 39 74 ) pg/mLET水平明显高于GG基因型 (72 9± 33 8)pg/mL。 结论　eNOS基因G894T多态性的T等位基因与中国汉族人EH的发生相关 ,T等位基因携带者可能通过减少内皮NO的释放参与EH发病。     

Nitric Oxide and its Role in Blastocyst Implantation

Reviews in Endocrine and Metabolic Disorders -     

肝癌组织中一氧化氮合酶及其基因表达的研究

目的研究肝癌组织中一氧化氮合酶(iNOS)及其基因表达与肝癌发生发展的关系。方法用免疫组化和原位杂交的方法对21例肝癌及癌旁组织中的诱导型一氯化氮合酶(iNOS)及其基因表达进行原位检测和观察。结果:NOS 阳性反应物质呈黄色或棕黄色,位于细胞浆中。非癌殖织(肉眼观距癌组织边缘>1.5)多呈阴性或弥漫弱阳性,但部分非癌组织中可见 iNOS 呈阳性的细胞呈点状分布;癌旁组织多呈阳性,提示 iNOS 表达与肝组织癌变有关。癌组织核心多呈阴性或弥漫弱阳性,但分化中和差的癌组织核心也分别有一例 NOS 呈强阳性;周边癌组织呈局灶阳性,侵入纤维组织中的弥敢癌细胞星强阳性,提示 NOS 的表达与肝癌组织的侵润能力有关。肝癌组织 iNOSmRNA 阳性细胞的分布与 iN-OS 蛋白的表达基本相似。结论 iNOS 蛋白及其基因表达与肝组织癌变及肝癌侵润能力有关。     

S-nitrosylation/activation of COX-2 mediates NMDA neurotoxicity

Glutamate/N-methyl-d-aspartate (NMDA) receptor-mediated neurotoxicity involves cyclooxygenase (COX)-2. We demonstrate that this neurotoxicity reflects activation of COX-2 by S-nitrosylation after selective binding of neuronal nitric oxide synthase (nNOS) to COX-2. nNOS, via its PDZ domain, binds COX-2 with the generated NO S-nitrosylating and activating the enzyme. Selective disruption of nNOS-COX-2 binding prevents NMDA neurotoxicity.     

人胃癌组织中一氧化氮合酶的表达

目的探讨NOS与胃癌的关系.方法用NADPH-d组织化学法测定了正常胃组织、癌旁组织和癌组织中一氧化氮合酶(NOS)表达水平.结果正常胃组织中粘膜上皮细胞、各种有分泌功能的细胞及肌层神经纤维中均有NOS表达,测一个视野NOS阳性细胞的平均灰度,正常胃组织为112、癌旁组织为120、胃癌组织为145.各组间差异有显著意义.表明正常胃组织NOS活性最高,胃癌组织NOS活性最低.结论①正常胃组织有广泛的NOS分布,提示NO对维持正常胃功能具有重要作用;②胃粘膜细胞癌变过程中,NOS活性明显降低,提示NOS活性与胃粘膜细胞癌变有高度相关性.     

Expression of inducible nitric oxide synthase in human gastric cancer

INTRODUCTIONInduciblenitricoxidesynthase(iNOS)isanenzymethatcatalyzestheformationofnitric0xide(N0)fromL-arginine.iNOSexpressionandactivityresultsintheproduction0fhighlevelsofNO[1].ThegenerationofphysiologicallevelsofNOisimp0rtantformucosalfunctionanditalsoexertsacytoprotectiveeffectonthegastr0intestinalmucosa.However,increasediNOSexpressionhasbeenobservedinpatientswithchronicinflammatorydiseasesofthegastr0intestinaltract,suchasulcerativec0litis[2'3],andgastritis['Jandithasbeenspecul…     

Nitrotyrosine and NO synthases in infants with respiratory failure: influence of inhaled NO

Inhaled nitric oxide (NO) is a selective vasodilator in pulmonary hypertension. However, the safety of inhaled NO (iNO) has not been established. Using an immunohistochemical technique, we studied the expression of NO synthase (NOS) isoforms NOS1, NOS2, NOS3, and nitrotyrosine, the marker of toxic NO-superoxide pathway, in lung specimens from autopsies. Twelve infants dying with respiratory failure had iNO up to 60 parts per million for 0.1-15 days. Twelve control infants were matched in pairs on the basis of the diagnosis, number of gestational days at birth, age at death, and whether extracorporeal perfusion was required. In addition, 5 infants who died of SIDS or nonpulmonary trauma (healthy lungs) were compared to 8 age-matched cases with respiratory failure. Immunostaining was graded by the intensity of the color deposit and the frequency in specific cells stained. Inhaled NO tended to increase NOS2 expression in bronchiolar epithelium and adjacent tissue. There were no other differences in the distribution of nitrotyrosine or NOS isoforms between iNO-treated infants and the control group with respiratory failure. All NOS isoforms were evident in the lungs studied. In severe respiratory failure, nitrotyrosine was mostly detectable in the bronchiolar epithelium and alveolar exudates, whereas in healthy lungs those sites did not contain nitrotyrosine. The alveolar tissue of infants with progressive respiratory may be affected by the NO-superoxide pathway. However, inhalation of NO was not associated with a detectable increase in oxidant stress.     

洛汀新对原发性高血压患者NOS活性及NO的影响

目的:探讨血管紧张素转换酶抑制剂洛汀新对原发性高血压（EH）患者的降压作用及其对NO和NOS水平的影响。方法:采用每日1次洛汀新10 mg治疗EH患者（21例）8周,观察治疗前、后血压和血小板（Pt）NO水平及NOS活性的变化。结果:EH患者Pt的NOS活性和NO水平显著低于正常对照组（14例）（P<0.01）。经洛汀新治疗后EH患者的血压显著降低（P<0.01）,Pt的NO产生量及NOS活性显著升高（P<0.01）。结论:洛汀新可降低血压、调节血小板NOS的活性和NO分泌量。