Expression of natriuretic peptides, nitric oxide synthase, and guanylate cyclase activity in frog mesonephros during the annual cycle

Natriuretic peptides (NPs), a family of structurally related hormones and nitric oxide (NO), generated by nitric oxide synthase (NOS), are believed to be involved in the regulation of fluid balance and sodium homeostasis. Differential expression and regulation of these factors depend on both physiological and pathological conditions. Both NPs and NO act in target organs through the activation of guanylate cyclase (GC) and the generation of guanosine 3',5'-cyclic monophosphate (cGMP), which is considered a common messenger for the action of these factors. The present study was designed to investigate--by histochemical methods--the expression of some NPs (proANP and ANP) and isoforms of NOS (neuronal NOS, nNOS, and inducible NOS, iNOS) in the mesonephros of Rana esculenta in different periods of the year including hibernation, to evaluate possible seasonal changes in their expression. We also studied the enzyme activity of NOS-related nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) and of GC. The experiments were performed on pieces of kidney of R. esculenta collected in their natural environment during active and hibernating life. The study was carried out using immunohistochemical techniques to demonstrate proANP, ANP, and some NOS isoforms. Antigen capture by enzyme linked immunosorbent assay (ELISA) was also performed to determine the presence of NPs in the frog kidney extract. Enzyme histochemistry was used to demonstrate the NOS-related NADPHd activity at light microscopy; GC activity was visualized at the electron microscope, using cerium as capture agent. The application of the immunohistochemical techniques demonstrated that frog mesonephros tubules express different patterns of distribution and/or expression of ANP and NOS during the annual cycle. Comparing the results obtained on active and hibernating frogs has provided interesting data; the NOS/NADPHd and GC activities showed some variations as well. Furthermore, the presence of NPs in the frog kidney extract was evidenced by dose-dependent response in the ELISA. The data suggest that both ANP and NO are intra-renal paracrine and/or autocrine factors which may modulate the adaptations of frog renal functions to seasonal changes through the action of the cGMP generated from GC activity.     

糖尿病大鼠胃窦胆碱能神经元与胃动力障碍的关系

目的 探讨链脲佐菌素(STZ)-糖尿病大鼠胃动力障碍和胃肌间神经丛胆碱能之间的关系.方法 45只SD大鼠随机分为对照组、糖尿病组和胰岛素组.成模后16 w测定大鼠胃动力,观察胃肌间神经丛胆碱能神经元的形态变化.结果 与对照组比较,糖尿病组大鼠胃动力减弱(P<0.01),胃窦肌间神经丛胆碱能神经元计数显著降低(P<0.01).与糖尿病组相比较,胰岛素组胃动力显著增高 (P<0.05),胃窦肌间神经丛胆碱能神经元平均光密度显著增高(P<0.05),胆碱能神经元计数有改善的趋势(P>0.05).结论 STZ-糖尿病大鼠胃动力障碍可能与胃肌间神经丛胆碱能神经损伤有关,胰岛素治疗能在一定程度上改善糖尿病胃动力障碍.     

不同HO-1表达水平对糖尿病模型大鼠血管舒张功能及NOS的影响

目的 探讨改变血红素加氧酶-1(HO-1)表达水平对糖尿病(DM)大鼠血管舒张功能的影响及与一氧化氮合酶(NOS)/一氧化氮(NO)的关系.方法 以链脲佐菌素(STZ)诱导DM大鼠模型.SD大鼠分成4组:对照组、DM组、正铁血红素(HO-1诱导剂)组、锌原卟啉(HO-1抑制剂)组.应用离体血管张力检测技术观察胸主动脉舒张功能变化;RT-PCR法及比色法分别检测血管组织和血清中诱生型NOS(iNOS)及内皮型NOS(eNOS)的表达和NO含量.结果 与DM组相比,正铁血红素组血管环对乙酰胆碱舒张百分率有所提高,而锌原卟啉组血管舒张反应继续下降.应用正铁血红素可在提高DM大鼠血管和血清eNOS表达的同时降低iNOS/NO表达;而锌原卟啉组血清中iNOS活性及其在血管组织表达均增高.结论 提高HO-1的表达水平有益于改善DM大鼠血管舒张反应失调,这种保护作用与抑制iNOS/NO的生成、上调eNOS表达水平有关.     

内皮细胞型一氧化氮合酶基因多态性与糖尿病肾病的相关性研究

目的：探讨内皮细胞型一氧化氮合酶（eNOS)基因第7外显子894G→T点突变,及其第4内含子的1个27bp的插入／缺失（a/b)多态性,与2型糖尿病肾病（DN）之间的关系。方法：894G→T点突变采用聚合酶链反应限制性片段长度多态性（PCR－RFLP）技术,27bp的a/b多态性采用聚合酶链反应结合4％琼脂糖凝胶电泳分离技术。比较各组间的等位基因频率与基因型频率。结果：（1）早期糖尿病肾病组（DN^ 组）T等位基因及TG基因型频率显著高于糖尿病非肾病患者（DN^-组,P＜0．05）。（2）DN^ 组a等位基因及ab基因型频率显著高于DN^-组（P＜0．05）。（3）DN^ 组的TGab基因型频率亦显著高于DN^-组（P＜0．05）。（4）糖基化血红蛋白（GHbA1c),收缩压（SBP）,总胆固醇（TC）,eNOS基因第7外显子894G→T基因点突变及第4内含子a/b多态性均属糖尿病肾病的独立危险因素。结论：糖尿病患者eNOS基因第7外显子T等位基因及第4内含子a等位基因与DN^ 的发生密切相关,两种等位基因同时存在者,DN^ 发病风险更高。     

慢性心力衰竭患者外周血中血浆肾素活性和利钠肽水平的变化及卡维地洛对其影响

目的　观察慢性心力衰竭 (心衰 )患者外周血中血浆肾素活性 (PRA)、心钠肽 (ANP)及脑钠肽 (N BNP)水平的变化及卡维地洛对其影响。方法　 6 0例慢性心衰患者随机分为常规治疗组 (血管紧张素转换酶抑制 +利尿剂 +地高辛 )和卡维地洛组 (常治疗药物 +卡维地洛 ) ,随访 12w ,采用放射免疫法测定二组治疗前后和 30例健康体检者 (正常对照组 )外周血中PRA、ANP、及N BNP水平。同时使用核素心室显像测定心衰患者左心室射血分数 (LVEF)。结果　心衰患者外周血中PRA、ANP及N BNP水平较正常对照组显著升高 ,其中ANP及N BNP水平在卡维地洛治疗前与LVEF负相关 ,在卡维地洛治疗后与LVEF密切相关 ,但PRA水平与LVEF无关。治疗后卡维地洛组外周血中PRA、ANP及N BNP水平较常规治疗组下降更明显。结论　外周血中ANP及N BNP水平在慢性心衰的病理生理机制中起着重要作用 ,甚至在 β受体阻滞剂治疗后仍可用于指导心衰患者的治疗。β受体阻滞剂能抑制心衰患者神经内分泌的过度激活。     

内皮型一氧化氮合酶基因多态性与糖尿病肾病的关系

目的 探讨内皮型一氧化氮合酶(eNOS)基因27bp数目可变的串联重复序列(VNTR)多态性与糖尿病肾病(DN)的关系。方法 应用PCR方法检测了32名健康对照者与84例2型糖尿病(T2DM)患者的eNOS基因a／b基因型，用硝酸盐还原酶法测定上述人群空腹血清一氧化氮代谢物(NOx)水平。并根据24h尿白蛋白排泄率(UAER)将84例T2DM患者分为正常白蛋白尿(UAlb)组(DMl)，微量UAlb组(I)M2)和大量UAlb组(I)M3)。结果 (1)T2DM各组a等位基因频率显著高于对照组，T2DM各组aa ab基因型频率明显高于对照组。DMl组a等位基因频率及aa ab基因型频率高于DM2及DM3组，但差异无显著意义。(2)NC组aa ab基因型空腹血清NOx明显低于bb基因型。(3)血清NOx在DMl组较NC组有明显的升高，但在DM2、DM3组却较NC组显著降低。(4)T2DM患者中，aa ab基因型UAER和血清肌酐(Scr)水平显著高于bb基因型。结论 eNOS基因27bpVNTR多态性与DN发生有关，eNOS基因a等位基因是DN发生和发展的有用的预测标志。     

内皮细胞一氧化氮合酶4 a/b基因多态性与糖尿病肾病的关系

昆明汉族人2型糖尿病患者334例和正常对照者166例研究显示，内皮细胞NO合酶4a／b基因多态性并不与糖尿病肾病的发生相关。     

利钠多肽对慢性心力衰竭伴睡眠呼吸暂停患者心功能的评价

目的 探讨以利钠多肽评价伴睡眠呼吸暂停慢性心力衰竭患者心功能的可能性.方法 64例慢性充血性心力衰竭（心衰）住院患者,经多导睡眠监测分为两组,心衰伴睡眠呼吸暂停组36例和心衰不伴睡眠呼吸暂停组28例.观察两组患者的一般资料、血气分析、心功能和体液因子变化,采用双抗夹心ELISA定量和竟争EIA定量法测定心钠素和脑钠素水平.结果 心衰伴睡眠呼吸暂停组左室舒张末期内径、左房前后径、纽约心功能分级、房性利钠多肽前体（proANP）、N-端室性利钠多肽前体（Nt-proBNP）水平增加;左室射血分数、血氧饱和度（SaO2）下降.左室射血分数＜45%心衰患者较≥45%心衰患者原发性心肌病多见;心功能各项检查的多元相关分析：左室射血分数与左室舒张末期内径和Nt-proBNP呈负相关（r=-0.662,P=0.000和r=-0.307 P=0.009）;左室舒张末期内径与左房前后径呈正相关（r=0.491,P=0.000）;左房前后径与proANP和Nt-proBNP呈正相关（r=0.432,P=0.000和r=0.295,P=0.012）;proANP与Nt-proBNP呈正相关（r=0.784,P=0.000）.心衰的多种影响因素多元线性回归分析：冠心病、纽约心功能分级、左室舒张末期内径、proANP和Nt-proBNP与左室射血分数呈负相关（P=0.000、P=0.031、P=0.000、P=0.004、P=0.000）.结论 睡眠呼吸暂停对64例心衰住院患者的心功能产生影响;利钠多肽与心脏超声所测左室射血分数在评价心功能方面呈负相关.     

甲状腺激素对大鼠小脑,海马,嗅脑神经元型一氧化氮合酶基因表达的调节

目的　观察 15日龄大鼠小脑 ,海马 ,嗅脑一氧化氮 (NO)含量 ,一氧化氮合酶 (NOS)活性的变化及甲状腺激素对上述部位神经元型一氧化氮合酶 (nNOS)基因表达的调节。方法　采用丙基硫氧嘧啶 (PTU)给孕母鼠灌胃造成仔鼠甲减动物模型 ;采用NO ,NOS生化测定法及nNOSmRNA半定量逆转录聚合酶链反应 (RT PCR)法。结果　无论正常组还是甲减组 ,NO含量 ,NOS活性及nNOSmRNA转录均以小脑为最高 ,嗅脑次之 ,海马最低 (P <0 .0 5 ) ;正常组NO含量 ,NOS活性nNOSmRNA转录均高于甲减组 (P <0 .0 1)。结论　提示甲状腺激素对nNOS基因表达有上调作用 ,NO信号系统可能参与大鼠小脑 ,海马 ,嗅脑等区甲状腺激素缺乏所造成的脑损害过程。     

A direct comparison of the natriuretic peptides and their relationship to survival in chronic heart failure of a presumed non-ischaemic origin

The natriuretic peptides have been validated as sensitive and specific markers of left ventricular dysfunction; brain natriuretic peptide (BNP), N-terminal atrial natriuretic peptide (NT-proANP) and N-terminal brain natriuretic peptide (NT-proBNP) elevations have been associated with New York Heart Association (NYHA) Class I-IV heart failure. We directly compared the association of each of these markers with 1-year survival in 173 patients with chronic heart failure of a presumed nonischaemic origin entering the PRAISE-2 Trial, a clinical study which assessed the therapeutic effect of Amlodipine in patients with NYHA Class III and IV heart failure and a left ventricular ejection fraction (LVEF) <30%. BNP, NT-proBNP, and NT-proANP levels were all correlated with 1-year mortality by univariate Cox proportional hazards analyses. With respect to multivariate Cox proportional hazards regression models containing variables deemed significant in univariate analyses, NT-proANP alone was identified as an independent predictor of 1-year mortality when log-transformed continuous covariates were utilized in the analysis. When the analysis was repeated using dichotomous covariates, NT-proANP remained the most significant predictor of 1-year mortality, followed by NT-proBNP, NYHA classification and BNP. We conclude that all three natriuretic peptides are significant predictors of short-term mortality in subjects with chronic congestive heart failure (CHF) of a presumed nonischaemic origin. Larger prospective studies are required to validate the clinical utility of NT-proANP as a discriminating marker of short-term survival, and to validate proposed cutoffs of approximately 2300 pmol/l for NT-proANP, 1500 pg/ml for NT-proBNP, and 50 pmol/l for BNP as prognostic indicators of adverse short-term outcome.     

Transgenic overexpression of brain natriuretic peptide prevents the progression of diabetic nephropathy in mice

Aims/hypothesis Brain natriuretic peptide (BNP) is a potent vasorelaxing and natriuretic peptide that is secreted from the heart and has cardioprotective properties. We have previously generated hypotensive transgenic mice (BNP-Tg mice) that overproduce BNP in the liver, which is released into the circulation. Using this animal model, we successfully demonstrated the amelioration of renal injury after renal ablation and in proliferative glomerulonephritis. Glomerular hyperfiltration is an early haemodynamic derangement, representing one of the key mechanisms of the pathogenesis of diabetic nephropathy. Based on the suggested involvement of increased endogenous natriuretic peptides, the aim of this study was to investigate their role in the development and progression of diabetic nephropathy. Materials and methods We evaluated the progression of renal injury and fibrogenesis in BNP-Tg mice with diabetes induced by streptozotocin. We also investigated the effect of BNP on high glucose-induced signalling abnormalities in mesangial cells. Results After induction of diabetes, control mice exhibited progressively increased urinary albumin excretion with impaired renal function, whereas these changes were significantly ameliorated in BNP-Tg mice. Notably, diabetic BNP-Tg mice revealed minimal mesangial fibrogenesis with virtually no glomerular hypertrophy. Glomerular upregulation of extracellular signal-regulated kinase, TGF-β and extracellular matrix proteins was also significantly inhibited in diabetic BNP-Tg mice. In cultured mesangial cells, activation of the above cascade under high glucose was abrogated by the addition of BNP. Conclusions/interpretation Chronic excess of BNP prevents glomerular injury in the setting of diabetes, suggesting that renoprotective effects of natriuretic peptides may be therapeutically applicable in preventing the progression of diabetic nephropathy.     

Endothelial cell-specific overexpression of endothelial nitric oxide synthase in Ins2Akita mice exacerbates diabetic nephropathy

Previous studies demonstrated that global deficiency of eNOS in diabetic mice exacerbated renal lesions and that overexpression of eNOS may protect against tissue injury. Our study revealed for the first time overexpression of eNOS leads to disease progression rather than protection. Transgenic mice selectively expressing eNOS in endothelial cells (eNOSTg) were cross bred with Ins2Akita type-1 (AK) diabetic mice to generate eNOS overexpressing eNOSTg/AK mice. Wild type, eNOSTg, AK and eNOSTg/AK mice were assessed for kidney function and blood glucose levels. Remarkably, overexpressing eNOSTg mice showed evidence of unpredicted glomerular injury with segmental mesangiolysis and occasional microaneurysms. Notably, in eNOSTg/AK mice overexpression of eNOS led to increased glomerular/endothelial injury that was associated with increased superoxide levels and renal dysfunction. Results indicate for the first time that overexpressing eNOS in endothelial cells cannot ameliorate diabetic lesions, but paradoxically leads to progression of nephropathy likely due to eNOS uncoupling and superoxide upsurge. This novel finding has a significant impact on current therapeutic strategies to improve endothelial function and prevent progression of diabetic renal disease. Further, the eNOSTg/AK model developed in this study has significant translational potentials for elucidating the underlying mechanism implicated in the deflected function of eNOS in diabetic nephropathy.     

Clinical benefits of natriuretic peptides and galectin-3 are maintained in old dyspnoeic patients

BackgroundAcute dyspnoea is the leading cause of unscheduled admission of elderly patients. Several biomarkers are used to diagnose acute heart failure (AHF) and assess prognosis of dyspnoeic patients, but their value in elderly patients is unclear. Objective: To compare diagnostic and prognostic performances of conventional and novel cardiovascular biomarkers in 2 age groups: young (<75 years old) vs. old (≥75 years old) dyspnoeic patients.DesignProspective observational registry.SettingEmergency department (ED).SubjectsAcutely dyspnoeic adult patients.MethodsBlood samples were collected at ED admission. The diagnostic value of 4 natriuretic peptides (BNP, proBNP, NT-proBNP, MR-proANP) for AHF was tested. We also assessed the prognostic value of same natriuretic peptides and of 3 novel cardiovascular biomarkers (galectin-3, sST2 and proenkephalin), using 1-year all-cause mortality as end-point. Diagnostic or prognostic performances are expressed as area under the receiveroperating characteristic curve (AUC) with 95% confidence interval.ResultsTwo hundred one acutely dyspnoeic patients were studied. AHF was the cause of dyspnoea in 57% of old and 44% of young patients, respectively. All 4 natriuretic peptides performed well in diagnosing AHF in both age groups (all AUC > 0.7). BNP showed the best diagnostic performance in both old (AUC: 0.98 [0.97–1.00]) and young (AUC 0.98 [0.95–1.00]) patients. Galectin-3 showed the best prognostic performance in both old (AUC 0.74 [0.62–0.87]) and young patients (AUC 0.75 [0.56–0.94]).ConclusionsBNP and galectin-3 show good clinical benefits in both oldand young acutely dyspnoeic patients.     

氧化型低密度脂蛋白对血小板一氧化氮合成酶的抑制作用及卡托普利的上调作用

目的　研究氧化型低密度脂蛋白 ( ox-L DL)对血小板一氧化氮合成酶 ( NOS)的抑制作用及卡托普利的抗氧化作用及对 NOS活性的上调作用。方法　测定 5 0例动脉粥样硬化患者和 3 0例健康老年体检者血小板悬液 NOS及加入 ox-LDL、卡托普利后 NOS活性的变化。结果　动脉粥样硬化组血小板 NOS活性明显低于对照组 ( P<0 .0 5 ) ;动脉粥样硬化组和对照组血小板加入 ox-LDL 后 NOS活性均显著降低 ( P<0 .0 1) ;两组血小板同时加入ox-LDL 和卡托普利后 NOS活性均明显升高 ( P<0 .0 1) ;两组血小板单纯加卡托普利后 NOS活性均明显升高 ( P<0 .0 1)。血小板 NOS活性变化与 ox-L DL呈负相关 ( r=-0 .989,P<0 .0 1) ,与卡托普利呈正相关 ( r=0 .987,P<0 .0 1)。结论　 ox-LDL能抑制血小板 NOS活性 ,而卡托普利不仅有抗氧化作用 ,还能直接上调 NOS活性     

Endothelial nitric oxide synthase dysfunction in diabetic mice: importance of tetrahydrobiopterin in eNOS dimerisation

Aims/hypothesis Impaired nitric oxide (NO) bioactivity and increased superoxide (SO) production are characteristics of vascular endothelial dysfunction in diabetes. The underlying mechanisms remain unknown. In this regard, we investigated the role of tetrahydrobiopterin (BH4) bioavailability in regulating endothelial nitric oxide synthase (eNOS) activity, dimerisation and SO production in streptozotocin-induced diabetic mice.Methods Mouse aortas were used for assays of the following: (1) aortic function by isometric tension; (2) NO by electronic paramagnetic resonance; (3) SO by lucigenin-enhanced chemiluminescence and dihydroethidine fluorescence; (4) total biopterin and BH4 by high-performance liquid chromatography; and (5) eNOS protein expression and dimerisation by immunoblotting.Results In diabetic mouse aortas, relaxations to acetylcholine and NO levels were significantly decreased, but SO production was increased, in association with reductions in total biopterins and BH4. Although total eNOS levels were increased in diabetes, the protein mainly existed in monomeric form. Conversely, specifically augmented BH4 in diabetic endothelium preserved eNOS dimerisation, but the expression remained unchanged.Conclusions/interpretation Our results demonstrate that BH4 plays an important role in regulating eNOS activity and its functional protein structure, suggesting that increasing endothelial BH4 and/or protecting it from oxidation may be a rational therapeutic strategy to restore eNOS function in diabetes.     

Effects of endogenous nitric oxide induced by 5-fluorouracil and L-Arg on liver carcinoma in nude mice

AIM： To study the effects of endogeous nitric oxide induced by 5-fluorouracil （5-FU） and L-arginine （L-Arg） on the human liver carcinoma model in nude mice. METHODS： The human liver carcinoma model in nude mice was established with BEL-7402 cells and normal saline （NS）, 5-FU and 5-FU ＋ L-Arg injected intraperitoneally. The tumor size was measured. The necrotic degree and range were observed under microscope. The apoptosis of cancer cell was detected by turmina deoxynucleotidyl transferanse mediated dUTP nick end labeling （TUNEL） method. Immunohistochemical method was performed to determine the expression of iNOS, P16, BAX. The chemical colorimetry was used to test the activity and nitrate reductase method was adopted to test the concentration of nitric oxide （NO） in the tumor tissue. The BI2000 pathological image analyzer was used to analyze the result of immunohistochemistry. RESULTS： 5-FU combined with L-Arg could inhibit the tumor growth apparently. In NS, 5-FU and 5-FU＋L- Arg groups, the changes of tumor volumes were 257.978 ± 59.0, 172.232 ± 66.0 and 91.523 ± 26.7 mm3, respectively （P 〈 0.05 5-FU vs 5-FU ± L-Arg group;P 〈 0.05 NS ys 5-FU ± L-Arg group; P 〈 0.05, NS ys 5-FU group）. The necrotic range and apoptosis index were significantly increased after the drug injection. The necrotic range was biggest in 5-FU ＋ L-Arg group （X^2= 15.963, P 〈 0.05）. The apoptosis indexes were as follows： NS, 17.4% ± 6.19%; 5-FU, 31.3% ± 12.3%; and 5-FU ± L-Arg, 46% ± 15.24% （P 〈 0.05, 5-FU ys 5-FU ± L-Arg; P 〈 0.05, NS ys 5-FU ± L-Arg; P 〈 0.05, NS ys 5-FU）. The expression and activity of iNOS were increased in the tumor tissue. The concentration of NO was also increased. F of opticaldensity of iNOS, iNOS activity and NO concentration are 31.693, 21.949, and 33.909, respectively, P 〈 0.05. The concentration of NO was related to the expression of PI6 and BAX. The correlation coefficient was 0.764 and 0.554. CONCLUSION： 5-FU combined with L-Arg can inhi     

Natriuretic peptides in the monitoring of anthracycline induced reduction in left ventricular ejection fraction

BACKGROUND: The use of anthracyclines in treatment of cancer is limited by cardiotoxicity of these compounds and may lead to heart failure. Therefore monitoring of cardiac function is necessary during therapy. AIM: We evaluated the value of natriuretic peptides (N-terminal pro-atrial natriuretic peptide (N-ANP) and brain natriuretic peptide (BNP)) for monitoring and predicting anthracycline induced cardiotoxicity using radionuclide left ventricular ejection fraction (EF) measurements as reference. METHODS AND RESULTS: A total of 107 consecutive patients receiving anthracycline as part of their chemotherapy for malignant disease were studied. Plasma concentrations of the peptides were measured by radioimmunoassay and EF by radionuclide cardiography. For reduced EF values, i.e. below 0.50 a fairly strong correlation was found between N-ANP or BNP and EF. Of 48 patients with serial EF and peptide measurements, 19% showed a significant EF decrease (>0.10) and ended with a final EF value below 0.50. Baseline EF was no predictor of a change in EF during treatment. Neither baseline levels of N-ANP or BNP nor a change in the same variables during therapy were predictive of a change in EF. CONCLUSIONS: In spite of correlations between peptide concentrations and reduced EF values neither baseline values nor serial measurements can safely substitute EF monitoring in patients undergoing anthracycline therapy.     

Critical role of inducible nitric oxide synthase in degeneration of retinal capillaries in mice with streptozotocin-induced diabetes

Aims/hypothesis Diabetes results in the upregulation of the production of several components of the inflammatory response in the retina, including inducible nitric oxide synthase (iNOS). The aim of this study was to investigate the role of iNOS in the pathogenesis of the early stages of diabetic retinopathy using iNOS-deficient mice (iNos ^−/−). Materials and methods iNos ^−/− mice and wild-type (WT; C57BL/6J) mice were made diabetic with streptozotocin or kept as non-diabetic controls. Mice were killed at different time points after the induction of diabetes for assessment of vascular histopathology, cell loss in the ganglion cell layer (GCL), retinal thickness, and biochemical and physiological abnormalities. Results The concentrations of nitric oxide, nitration of proteins, poly(ADP-ribose) (PAR)-modified proteins, endothelial nitric oxide synthase, prostaglandin E₂, superoxide and leucostasis were significantly (p < 0.05) increased in retinas of WT mice diabetic for 2 months compared with non-diabetic WT mice. All of these abnormalities except PAR-modified proteins in retinas were inhibited (p < 0.05) in diabetic iNos ^−/− mice. The number of acellular capillaries and pericyte ghosts was significantly increased in retinas from WT mice diabetic for 9 months compared with non-diabetic WT controls, these increases being significantly inhibited in diabetic iNos ^−/− mice (p < 0.05 for all). Retinas from WT diabetic mice were significantly thinner than those from their non-diabetic controls, whereas diabetic iNos ^−/− mice were protected from this abnormality. We found no evidence of cell loss in the GCL of diabetic WT or iNos ^−/− mice. Deletion of iNos had no beneficial effect on diabetes-induced abnormalities on the electroretinogram. Conclusions/interpretation We demonstrate that the inflammatory enzyme iNOS plays an important role in the pathogenesis of vascular lesions characteristic of the early stages of diabetic retinopathy in mice. An erratum to this article can be found at     

2型糖尿病患者内皮一氧化氮合酶基因(CA)n多态性的分布及与糖尿病肾病的关系

目的探讨内皮一氧化氮合酶基因（CA）n多态性在新加坡2型糖尿病患者中的分布及与糖尿病肾病的关系。方法258例2型糖尿病患者入选。从全血中提取DNA，然后进行多聚酶链反应、凝胶电泳及测序。结果在新加坡的中国人、马来西亚人和印度人中各有23、22、20种（CA）n多态性，其基因型分布差异有统计学意义（P〈0．01）。新加坡中国人（CA）n的分布与欧洲白人差异有统计学意义。该基因多态性与糖尿病肾病无显著相关性。结论（CA）n多态性在新加坡3个种族中的分布差异有统计学意义，而且与欧洲白人的分布差异也有统计学意义，但与糖尿病肾病无显著相关性。