Elevated plasma concentration of NO and cGMP may be responsible for the decreased platelet aggregation and platelet leukocyte conjugation in platelets hypo-responsive to catecholamines

Impaired responsiveness to epinephrine and other catecholamines (CA) were previously reported in platelets of 20 ～ 30% healthy Japanese and Koreans. In the present study, the possible mechanisms of different responsiveness to CA in platelets of CA hypo-responders (CA-HY) and CA good-responders (CA-GR) were investigated. Increased platelet-leukocyte conjugate (PLC) formations were observed with whole blood of CA-GR than with that of CA-HY in both non-stimulated [mean fluorescence intensity (MFI) values: 1.33 ± 0.26 vs. 1.16 ± 0.19] and ADP (MFI: 5.54 ± 3.46 vs. 2.15 ± 1.13) or TRAP (MFI: 5.11 ± 2.32 vs. 3.38 ± 1.47) activated states. The platelets of CA-GR, when stimulated with ADP (10 µM), released approximately twice the amount of ATP than those of CA-HY (0.88 ± 0.65 and 0.45 ± 0.36 nmole, respectively). Nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) levels were significantly higher in non-stimulated PRP of CA-HY than in that of CA-GR (70.3 ± 24.1 µM and 14.1 ± 4.9 nM vs. 41.1 ± 15.8 µM and 6.7 ± 2.4 nM, respectively). The platelet-monocyte conjugation induced with either ADP or TRAP was significantly reduced in CA-GR with the addition of linsidomine, a NO donor, (MFI: 2.78 ± 0.43 vs. 3.73 ± 0.90, or 4.28 ± 0.95 vs. 5.76 ± 1.33, respectively). Moreover, the degree of platelet aggregation and the ATP secretion induced by epinephrine in CA-GR were significantly retarded with the addition of either linsidomine or 8-Bromo-cGMP (a cGMP analog) with more substantial effects on ATP release than aggregation. The results suggested that elevated NO and/or cGMP plasma levels may be responsible for the lower platelet aggregation and PLC formation observed in CA-HY than that in CA-GR.     

Attenuation of Intrinsic Active Tone by Endothelium-Derived Nitric Oxide in Aortae of Spontaneously Hypertensive Rats with Different Levels of Blood Pressure

The influences of endothelium on the basal tone of aortae from various strains of spontaneously hypertensive rats with different blood pressure (SHR, SHRSP, MSHRSP) were studied. Endothelium-intact preparations of aortac from spontaneously hypertensive rats exhibited spontaneous active tone, which was greater in the order of SHR < SHRSP < M-SHRSP. The active tone of the MSHRSP preparations was about 40% of high-K⁺-induced contraction, while that of normotensive WKY was less than 5%. The active tone was enhanced by the removal of endothelium. The active tone was sensitive to extracellular Ca²⁺ and abolished by verapamil. The application of N^G-monomethyl-L-arginine caused the increase in the active tone which was counteracted by L-arginine. These results indicate that the active tone of smooth muscle increases as the blood pressure of the rat increases, and that endothelium attenuates the active tone by releasing nitric oxide (NO) spontaneously. It was also demonstrated that the attenuating action of endothelium was impaired depending on the blood pressure level.     

The functional and structural changes in the basilar artery due to overpressure blast injury

Overpressure blast-wave induced brain injury (OBI) leads to progressive pathophysiologic changes resulting in a reduction in brain blood flow, blood brain barrier breakdown, edema, and cerebral ischemia. The aim of this study was to evaluate cerebral vascular function after single and repeated OBI. Male Sprague-Dawley rats were divided into three groups: Control (Naive), single OBI (30 psi peak pressure, 1 to 2 msec duration), and repeated (days 1, 4, and 7) OBI (r-OBI). Rats were killed 24 hours after injury and the basilar artery was isolated, cannulated, and pressurized (90 cm H₂O). Vascular responses to potassium chloride (KCl) (30 to 100 mmol/L), endothelin-1 (10⁻¹² to 10⁻⁷ mol/L), acetylcholine (ACh) (10⁻¹⁰ to 10⁻⁴ mol/L) and diethylamine-NONO-ate (DEA-NONO-ate) (10⁻¹⁰ to 10⁻⁴ mol/L) were evaluated. The OBI resulted in an increase in the contractile responses to endothelin and a decrease in the relaxant responses to ACh in both single and r-OBI groups. However, impaired DEA-NONO-ate-induced vasodilation and increased wall thickness to lumen ratio were observed only in the r-OBI group. The endothelin-1 type A (ET_A) receptor and endothelial nitric oxide synthase (eNOS) immunoreactivity were significantly enhanced by OBI. These findings indicate that both single and r-OBI impairs cerebral vascular endothelium-dependent dilation, potentially a consequence of endothelial dysfunction and/or vascular remodelling in basilar arteries after OBI.     

Human apolipoprotein A-I Gly26Arg stimulation of inflammatory responses via NF-kB activation: Potential roles in amyloidosis?

The cascade of molecular events leading to Human apolipoprotein A–I (apoA–I) amyloidosis is not completely understood, not even the pathways that determine clinical manifestations associated to systemic protein deposition in organs such as liver, kidney and heart. About twenty natural variants of apoA–I were described as inducing amyloidosis, but the mechanisms driving their aggregation and deposition are still unclear. We previously identified that the mutant Gly26Arg but not Lys107-0 induced the release of cytokines and reactive oxygen species from cultured RAW 264.7 murine macrophages, suggesting that part of the pathogenic pathway could elicit of an inflammatory signal. In this work we gained deep insight into this mechanism and determined that Gly26Arg induced a specific pro-inflammatory cascade involving activation of NF-κB and its translocation into the nucleus. These findings suggest that some but not all apoA–I natural variants might promote a pro-oxidant microenvironment which could in turn result in oxidative processing of the variants into a misfolded conformation.     

Peroxynitrite modified DNA may be an antigenic trigger for antibodies in various cancers of gynecologic origin

This study aimed towards probing the role of peroxynitrite damaged human DNA (ONOO^–-DNA) in the induction of circulating antibodies in certain cancers of gynecologic origin. We have compared the binding specificity of DNA isolated from the lymphocytes of cancer patients with that of the experimentally modified DNA. Also, the induced anti-ONOO⁻-DNA antibodies have been used to probe oxidative damage in the DNA isolated from cancer patients. Human placental DNA was modified with peroxynitrite (ONOO⁻) and analyzed by ultraviolet (UV) and fluorescence spectroscopy, gel electrophoresis, thermal denaturation profile, etc. Antibodies against modified DNA were induced in experimental animals. Specific binding of the antibodies was evaluated by ELISA and band shift assay. 91 cancer patients were selected and grouped according to the type of cancer. Specific binding characteristics of circulating autoantibodies (IgG) were determined by competitive-inhibition ELISA, using different inhibitors. Maximum inhibition of antibody activity by ONOO⁻-DNA reflected specific recognition of modified epitopes by cancer IgG. This shows generation of neo-epitopes on DNA, upon modification with ONOO⁻, that are recognized by cancer IgG. Our results indicate epitope sharing between the DNA isolated from cancer patients and the in-vitro modified ONOO⁻-DNA. The possible role of nitrosative stress in the gynecologic oncology has been discussed.     

纳洛酮对心肺复苏后犬血流动力学和心肌氧自由基、一氧化氮的影响

目的 观察纳洛酮(naloxone，NLX)对犬心跳骤停复苏后血流动力学和心肌氧自由基及一氧化氮(NO)的影响。方法体外电击诱发犬室颤，3min后复苏，18只犬随机分为3组：CPR组、NLX组、正常对照组，每组6只。采用Swan-Ganz漂浮导管监测复苏前和复苏后6h的CO和PAWP。6h后取心肌组织，匀浆检测超氧化物岐化酶(SOD)、丙二醛(MDA)和一氧化氮(NO)。结果CPR组的平均动脉压在复苏后4、6h低于正常对照组，而NLX组在复苏后2、4、6h高于CPR组，与正常对照组无差异。CO、Cl、SV和LVS,W1在心跳骤停前三组间差异无统计学意义，复苏成功后0-6h NLX组和CPR组的各指标均低于正常组，而NLX组的CO、CI、SV和LVSWI在复苏后1．6h高于CPR组。复苏后6h CPR组和NLX组心肌组织SOD活性则低于正常对照组，而MDA和NO高于正常对照组，NLX组心肌组织MDA和NO含量较CPR组降低，而SOD活力较CPR组升高。结论诱发室颤犬复苏成功后存在心功能不全、氧自由基和NO产生增加和内源性抗氧化机制的削弱，NLX能予以改善。     

结核性和癌性胸水中NO水平测定

用酶法检测结核性和非结核性胸水及血清中NO含量，结果显示．结核组NO水平明显升高（15±43μmol／l，）与癌性胸水组比有明显性差异（P＜0．01）。结核性胸水NO含量与SIL－2R呈正相关（r=0．654，P＜0.01），敏感性（97％）、特异性（82％）均较理想。测定购水中NO，对于结核性胸水诊断、鉴别诊断和病因学研究有一定意义。     

分娩发动对NO、NOS水平及产后出血的影响

目的 探讨剖宫产孕妇术前临产状态对其血清NO、NOS水平的影响以及在产后出血防治中的作用.方法 选择剖宫产终止妊娠的孕妇180例,因臀位、社会因素、骨盆狭窄、胎儿宫内窘迫等行剖宫产术,按剖宫产术前临产与否分为临产组（n=88）：阴道试产6小时以上者;未临产组（n=92）：未经阴道试产直接行剖宫产术者;所有孕妇分别于剖宫产术麻醉前30分钟及术后2小时测血清NO及NOS,术中娩出胎儿后于子宫切缘上缘及胎盘母体面中央无钙化区分别取子宫肌组织及胎盘组织各一,切片作免疫组织化学分析iNOS的表达,准确收集剖宫产术中出血量及产后24小时出血量.结果 未临产组产后24小时出血量及产后出血的发生率均大于临产组;无论是临产组还未临产组,术前到术后血清NO及NOS水平均呈逐渐下降的趋势,而且未临产组术前、术后血清NO及NOS含量较临产组明显增高,差异有显著性意义（P＜0.05）;未临产组子宫肌和胎盘的iNOS阳性表达率均显著高于临产组（P＜0.05）;术前、术后血清NO、NOS含量与产后24小时出血量均呈显著正相关.结论 分娩发动且经过充分阴道试产的孕妇,随着其体内NO、NOS水平及表达下降,削宫产产后出血的发生率也下降.