Inducible nitric oxide synthase, nitrotyrosine and apoptosis in gastric adenocarcinomas and their correlation with a poor survival

AIM: To detect the presence of inducible nitric oxide synthase (iNOS), nitrotyrosine (NT) and apoptosis in gastric adenocarcinomas and their possible correlations with the clinicopathological characteristics and prognosis of gastric adenocarcinoma.METHODS: Sixty-six specimens of gastric adenocarcinoma and corresponding adjacent normal gastric tissues were studied. Immunohistochemistry was employed to localize iNOS and NT protein and an immunohistochemical scoring system was used. The occurrence of apoptotic cell death (apoptotic index [AI]) was analyzed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling (TUNEL) method. RESULTS: Results showed that iNOS expression wasdetected at an intermediate or high level in 41 of 66 (62%) specimens of gastric adenocarcinoma. NT expression was 58%. Neither of them was found in the normal gastric tissues; there were significant positive correlations among iNOSexpression, NT expression and AI. Many clinicopathologic characteristics of gastric adenocarcinoma, such as tumor size, depth of invasion, lymph node metastasis and TNM staging, were related to iNOS and NT expressions (P＜0.05). In 66 surviving patients, the 5-year survival rate of 41 patients who had tumors with intermediate or high iNOS expressions and high Ais (4.09%; 19.96%) was significantly lower than that of 25 patients who had tumors with negative or low iNOS expressions and low Ais (0.79%; 47.14%) (P= 0.001). COX's multivariate analysis revealed that the iNOS expression was identified as one of the significant independent prognostic factors predictive of a poor survival (relative risk [RR] = 2.69).CONCLUSION: NO produced by iNOS may play a stronger role in promoting gastric adenocarcinoma growth than in suppressing its growth. iNOS and NT expressions by gastric adenocarcinoma may correlate with a poor survival.

Oxidative and nitrosative stress enzymes in relation to nitrotyrosine in Helicobacter pylori-infected humans

AIM: To compare a possible relation between Helicobacter pylori(H. pylori) and the oxygen- and nitrogen radical system in humans. METHODS: Mechanisms for H. pylori to interfere with the oxygen and nitrogen radical system is of great importance for understanding of the H. pylori persistence and pathogenesis. Biopsies were obtained from the gastric wall of 21 individuals. Ongoing infection with H. pylori was detected using direct analyze from the biopsies using campylobacter-like organism test(CLO-test) and/or by using 14C-urea breath test. The individuals were divided in a negative H. pylori and a positive H. pylori group. Expression in the gastric mucosa of induc-ible nitric oxide syntase(iNOS), nicotinamide adenine dinucleotide phosphate-oxidase(NADPH-oxidase) myeloperoxidase(MPO), and nitrotyrosine were assessed by Western blotting.RESULTS: The individuals who undervent gastroscopy were divided in a H. pylori neg. [n = 13, m/f = 7/6, age(mean) = 39] and a H. pylori pos. group [n = 8, m/f = 5/3, age(mean) = 53]. Using western blot analysis iNOS was detected as a 130 kDa band. The iNOS expression was upregulated in the antrum of H. pylori infected individuals in comparison to the controls, mean ± SD being 12.6 ± 2.4 vs 8.3 ± 3.1, P < 0.01. There was a markedly upregulated expression of MPO in the antrum of H. pylori infected individuals in comparison to the control group without infection. In several of noninfected controls it was not possible to detect any MPO expression at all, whereas the expression was high in all the infected subjects, mean ± SD being 5.1 ± 3.4 vs 2.1 ± 1.9, P < 0.05. The NADPH-oxidase expression was analysed by detecting the NADPH-oxidase subunit p47-phox expression. P47-phox was detected as a 47 kDa band using Western blot, and showed a significantly higher expression of p47-phox in the antrum of the H. pylori infected individuals compared to the controls, mean ± SD being 3.1 ± 2.2 vs 0.3 ± 0.2, P < 0.01. Regarding nitrotyrosine formation, Western blot did not show any significant increase or decrease compared to controls, 7.0 ± 0.9 vs 6.9 ± 1.1, not significant.CONCLUSION: iNOS, MPO and NADPH-oxidase was up-regulated among H. pylori infected. Regarding nitrotyrosine no difference was found. This support an H. pylori related inhibition of radical formation.

Noise-induced nitrotyrosine increase and outer hair cell death in guinea pig cochlea

Background Modern research has provided new insights into the biological mechanisms of noise-induced hearing loss, and a number of studies showed the appearance of increased reactive oxygen species （ROS） and reactive nitrogen species （RNS） during and after noise exposure. This study was designed to investigate the noise exposure induced nitrotyrosine change and the mechanism of outer hair cells death in guinea pig cochlea. Method Thirty guinea pigs were used in this study. The experimental animals were either exposed for 4 hours per day to broadband noise at 122 dB SPL （A-weighted） for 2 consecutive days or perfused cochleae with 5 mg/ml of the SIN1 solutions, an exogenous NO and superoxide donor, for 30 minutes. Then the cochleae of the animals were dissected. Propidium iodide （PI）, a DNA intercalating fluorescent probe, was used to trace morphological changes in OHC nuclei. The distribution of nitrotyrosine （NT） in the organ of Corti and the cochlear lateral wall tissue from the guinea pigs were examined using fluorescence immunohistochemistry method. Whole mounts of organ of Corti were prepared. Morphological and fluorescent changes were examined under a confocal microscope. Results Either after noise exposure or after SIN1 perfusion, outer hair cells （OHCs） death with characteristics of both apoptotic and necrotic degradation appeared. Nitrotyrosine immunolabeling could be observed in the OHCs from the control animals. After noise exposure, NT immunostaining became much greater than the control animals in OHCs. The apoptotic OHC has significant increase of nitrotyrosine in and around the nucleus following noise exposure. In the normal later wall of cochleae, relatively weak nitrotyrosine immunolabeling could be observed. After noise exposure, nitrotyrosine immunoactivity became stronger in stria vascularis. Conclusion Noise exposure induced increase of nitrotyrosine production is associated with OHCs death suggesting reactive nitrogen species participation in the cochlear pathophysiology of noise-induced hearing loss.

Effects and Clinical Significance of Pentoxifylline on the Oxidative Stress of Rats with Diabetic Nephropathy

Diabetic nephropathy（DN） is a common and serious clinical complication of diabetes and presently there are no effective ways to prevent its occurrence and progression. Recent studies show that pentoxifylline（PTX） can improve renal hemodynamics, reduce urinary protein excretion, and alleviate or delay renal failure in DN patients. In this study, we focused on the anti-oxidative stress effect of PTX on alleviating renal damages of DN using rat models. DN rats were established with injection of streptozotocin. Blood glucose, urinary protein excretion, serum cystatin C, renal biopsy, superoxide dismutase（SOD） and malondialdehyde（MDA） in serum and renal homogenate and renal nitrotyrosine levels were analyzed before and 12 weeks after the treatment of PTX. Before treatment, all the DN rats had elevated blood glucose, increased urinary protein excretion and elevated serum cystatin C. Morphologically, DN rats exhibited renal tissue damages, including swelling and fusions of foot processes of podocytes under electron microscope. Masson staining revealed blue collagen deposition in glomeruli and renal interstitium. With treatment of PTX, symptoms and renal pathological changes of DN rats were alleviated. Furthermore, the MDA levels were increased and the SOD levels were decreased in the serum and kidneys of DN rats, and these changes were reversed by PTX. The expression of nitrotyrosine was up-regulated in DN rat model and down-regulated by PTX, indicating that PTX was able to inhibit oxidative reactions in DN rats. PTX could alleviate renal damage in DN, which may be attributable to its anti-oxidative stress activity.

A silybin-phospholipids complex counteracts rat fatty liver degeneration and mitochondrial oxidative changes

AIM:To investigate the effectiveness of antioxidant compounds in modulating mitochondrial oxidative alterations and lipids accumulation in fatty hepatocytes.METHODS:Silybin-phospholipid complex containing vitamin E(Realsil) was daily administered by gavage(one pouch diluted in 3 mL of water and containing 15 mg vitamin E and 47 mg silybin complexed with phospholipids) to rats fed a choline-deprived(CD) or a high fat diet [20% fat,containing 71% total calories as fat,11% as carbohydrate,and 18% as protein,high fat diet(HFD)] for 30 d and 60 d,respectively.The control group was fed a normal semi-purified diet containing adequate levels of choline(35% total calories as fat,47% as carbohydrate,and 18% as protein).Circulating and hepatic redox active and nitrogen regulating molecules(thioredoxin,glutathione,glutathione peroxidase),NO metabolites(nitrosothiols,nitrotyrosine),lipid peroxides [malondialdehyde-thiobarbituric(MDA-TBA)],and pro-inflammatory keratins(K-18) were measured on days 0,7,14,30,and 60.Mitochondrial respiratory chain proteins and the extent of hepatic fatty infiltration were evaluated.RESULTS:Both diet regimens produced liver steatosis(50% and 25% of liver slices with CD and HFD,respectively) with no signs of necro-inflammation:fat infiltration ranged from large droplets at day 14 to disseminated and confluent vacuoles resulting in microvesicular steatosis at day 30(CD) and day 60(HFD).In plasma,thioredoxin and nitrosothiols were not significantly changed,while MDA-TBA,nitrotyrosine(from 6 ± 1 nmol/L to 14 ± 3 nmol/L day 30 CD,P < 0.001,and 12 ± 2 nmol/L day 60 HFD,P < 0.001),and K-18(from 198 ± 20 to 289 ± 21 U/L day 30 CD,P < 0.001,and 242 ± 23 U/L day 60 HFD,P < 0.001) levels increased significantly with ongoing steatosis.In the liver,glutathione was decreased(from 34.0 ± 1.3 to 25.3 ± 1.2 nmol/mg prot day 30 CD,P < 0.001,and 22.4 ± 2.4 nmol/mg prot day 60 HFD,P < 0.001),while thioredoxin and glutathione peroxidase were initially increased and then decreased.Nitrosothiols were constantly increased.MDA-TBA levels were five-fold increased from 9.1 ± 1.2 nmol/g to 75.6 ± 5.4 nmol/g on day 30,P < 0.001(CD) and doubled with HFD on day 60.Realsil administration significantly lowered the extent of fat infiltration,maintained liver glutathione levels during the first half period,and halved its decrease during the second half.Also,Realsil modulated thioredoxin changes and the production of NO derivatives and significantly lowered MDA-TBA levels both in liver(from 73.6 ± 5.4 to 57.2 ± 6.3 nmol/g day 30 CD,P < 0.01 and from 27.3 ± 2.1 nmol/g to 20.5 ± 2.2 nmol/g day 60 HFD,P < 0.01) and in plasma.Changes in mitochondrial respiratory complexes were also attenuated by Realsil in HFD rats with a major protective effect on Complex Ⅱ subunit CII-30.CONCLUSION:Realsil administration effectively contrasts hepatocyte fat deposition,NO derivatives formation,and mitochondrial alterations,allowing the liver to maintain a better glutathione and thioredoxin antioxidant activity.

Pathogenic role of oxidative and nitrosative stress in primary biliary cirrhosis

Primary biliary cirrhosis is a multifactor autoimmune disease characterized by hepatic and systemic manifestations,with immune system dysregulation and abnormalities in the hepatic metabolism of bile salts,lipids,and nutrients,as well as destruction of membrane lipids and mitochondrial dysfunction.Both oxidative and nitrosative stress are associated with ongoing manifestations of the disease.In particular,abnormalities in nitric oxide metabolism and thiol oxidation already occur at early stages,thus leading to the hypothesis that these biochemical events play a pathogenic role in primary biliary cirrhosis.Moreover,the association of these metabolic abnormalities with the progression of the disease may indicate some biochemical parameters as early diagnostic markers of disease evolution,and may open up the potential for pharmacological intervention to inhibit intra-and extra-cellular stress events for resuming hepatocellular functions.The following paragraphs summarize the current knowledge by outlining molecular mechanisms of the disease related to these stress events.

Associations between y-glutamyl transferase, metabolic abnormalities and inflammation in healthy subjects from a population-based cohort: A possible implication for oxidative stress

AIM: To examine the relationships between γ -glutamyltransferase (GGT), alanine-aminotransferase (ALT),aspartate-aminotransferase (AST) and various metabolic parameters, C-reactive protein (CRP) and an oxidative stress marker (nitrotyrosine, NT) in subjects without any metabolic abnormalities from a population-based sample.METHODS: Two hundred and five subjects with normal body mass index (BMI), glucose tolerance, and without any metabolic abnormality were studied out of 1339subjects, without known liver diseases, alcohol abuse or use of hepatotoxic drugs, who are representative of the 45-64 aged population of Asti (north-western Italy).RESULTS: In all patients metabolic parameters and hs-CRP levels linearly increase from the lowest to the highest ALT and GGT tertiles, while in subjects without metabolic abnormalities, there is a significant association between fasting glucose, uric acid, waist circumference,hs-CRP, triglyceride values, and GGT levels. In these subjects, male sex, higher hs-CRP and glucose levels are associated with GGT levels in a multiple regression model, after adjustments for multiple confounders.In the same model, median NT levels are significantly associated with the increasing GGT tertile (β = 1.06;95%CI 0.67-1.45), but not with the AST and ALT tertiles.In a multiple regression model, after adjusting for age,sex, BMI, waist, smoking, and alcohol consumption, both NT (β = 0.05; 95%CI 0.02-0.08) and hs-CRP levels (β =0.09; 95%CI 0.03-0.15) are significantly associated with fasting glycemia.CONCLUSION: GGT, an easy, universally standardized and available measurement, could represent an early marker of sub-clinical inflammation and oxidative stress in otherwise healthy individuals. Prospective studies are needed to establish if GGT could predict future diabetes in these subjects.

Effect of Triptolide on Expression of Oxidative Carbonyl Protein in Renal Cortex of Rats with Diabetic Nephropathy

The traditional Chinese medicine（Tripterygium wilfordii Hook.f., TWH） has been clinically used to treat primary and secondary renal diseases and proteinuria for nearly 40 years. However, there is a rare literature about the effect of triptolide（the main active ingredient of TWH） on the expression of oxidative carbonyl protein（OCP） in diabetic nephropathy（DN）. This study aimed to provide experimental evidence for triptolide treatment on DN through its effect on the expression of OCP, in order to investigate the effects of triptolide on the expression of OCP in rats with DN. Sixty SD rats were randomly divided into five groups： control group, high-dose triptolide（Th） group, low-dose triptolide（Tl） group, DN model group, and positive control（benazepril） group. The DN model was established using streptozotocin. Urinary protein excretion, fasting blood glucose（FBG）, superoxide dismutase（SOD） in renal homogenate, malondialdehyde（MDA） in renal homogenate and renal nitrotyrosine by immunohistochemistry, and the expression of OCP by oxyblotimmune blotting were detected. In the DN model group, rat urinary protein excretion and renal MDA were significantly increased, while renal SOD significantly decreased and nitrotyrosine expression was obviously upregulated in the kidney. After triptolide treatment, 24-h urinary protein excretion（61.96±19.00 vs. 18.32±4.78 mg/day, P〈0.001）, renal MDA（8.09±0.79 vs. 5.45±0.68 nmol/L, P〈0.001）, and nitrotyrosine expression were decreased. Furthermore, renal OCP significantly decreased, while renal SOD（82.50±19.10 vs. 124.00±20.52 U/L, P〈0.001） was elevated. This study revealed that triptolide can down-regulate the expression of OCP in the renal cortex of DN rats.

Levels of biological markers of nitric oxide in serum of patients with squamous cell carcinoma of the oral cavity

The aim of the study was a determination of the levels of nitric oxide（NO）and its biological markers such as malonyldialdehyde（MDA）and nitrotyrosine in the serum of patients with squamous cell carcinoma（SCC）of the oral cavity and identification of the relationships between NO and those markers.These studies were performed on patients with SCC of the oral cavity before and after treatment.Griess reaction was used for the estimation of the total concentration of NO in serum.The nitrotyrosine level in serum was assessed with an enzyme-linked immunosorbent assay（ELISA）kit,and MDA level using a spectrophotometric assay.Higher concentrations of NO in blood serum were determined in patients with stage IV of the disease before treatment in comparison to the control group and patients with stages II and III of the disease.Moreover,higher concentrations of MDA and nitrotyrosine were determined in the serum of patients in all stages of the disease in comparison to healthy people.After treatment,lower concentrations of NO in the serum of patients with stage IV of the disease were observed in comparison to the amounts obtained prior to treatment.In addition,lower levels of nitrotyrosine in the serum of patients with all stages of the disease were recorded,whereas higher concentrations of MDA were determined in these patients in comparison to results obtained before treatment.The compounds formed with the contribution of NO,such as MDA and nitrotyrosine,may lead to cancer progression in patients with SCC of the oral cavity,and contribute to formation of resistance to therapy in these patients as well.Moreover,the lack of a relationship between concentrations of NO and MDA,and between NO and nitrotyrosine in serum suggests that the process of lipid peroxidation and nitration in patients with SCC does not just depend on NO.

Evaluation of tetrahydrobiopterin(BH4)as a potential therapeutic agent to treat erectile dysfunction

Aim： Nitric oxide （NO）-mediated smooth muscle relaxation causes penile erections. The endothelial NO synthase （eNOS） coenzyme tetrahydrobiopterin （BH4） converts eNOS-mediated catalytic activity from oxygen radical to NO production, improving endothelial function and vascular smooth muscle relaxation. Methods： Using quantitative immunohistochemistry, 8-isoprostane and nitrotyrosine concentrations were compared in cavernosal tissue from 17 potent and 7 impotent men, and the effect of single oral doses of BH4 on penile rigidity and tumescence was investigated. The pharmacodynamic effect of single oral doses of BH4 on penile rigidity and tumescence was investigated in a randomized, placebo-controlled, double-blind cross-over fashion in 18 patients with erectile dysfunction （ED） while receiving visual sexual stimulation. Results： 8-isoprostane content in endothelium and smooth muscle was signifi- cantly higher in impotent patient samples; the level of nitrotyrosine was unchanged in ED patients. Relative to placebo, a single dose of 200 mg BH4 led to a mean increase in duration of 〉 60% penile rigidity （33.5 rain [95% confidence interval （CI）： 13.1-49.3] at base and 29.4 rain [95% CI： 8.9-42,2] at tip）. A 500-mg dose increased the relative duration of 〉 60% penile rigidity by 36. I rain （95% CI： 16.3-51.8） at the base and 33.7 rain （95% CI： 11.4-43.9） at the tip. Treatments were well tolerated. Conclusion： BH4 treatment is suggested to switch eNOS catalytic activity from super-oxide to NO formation, leading to a reduced formation of free radical reaction product 8-isoprostane without alteration of nitrotyrosine. The observed results make BH4 a suitable candidate as an ED treatment through reconstitution of altered catalytic activity of the eNOS. （Asian JAndro12006 Mar; 8： 159-167）

Differences in oxidative stress dependence between gastric adenocarcinoma subtypes

AIM： To investigate the extent of oxidative stress in preneoplastic and neoplastic gastric mucosa in relation to their pathological criteria and histological subtypes. METHODS： A total of 104 gastric adenocarcinomas from 98 patients （88 infiltrative and 16 intraepithelial tumors） were assessed immunohistochemically for expression of iNOS and occurrence of nitrotyrosine （NTYR）-containing proteins and 8-hydroxy-2＇-deoxyguanosine （8-OH- dG）-containing DNA, as markers of NO production and damages to protein and DNA. RESULTS： Tumor cells staining for iNOS, NTYR and 8-OH-dG were detected in 41%, 62% and 50% of infiltrative carcinoma, respectively. The three markers were shown for the first time in intraepithelial carcinoma. The expression of iNOS was significantly more frequent in tubular carcinoma （TC） compared to diffuse carcinoma （DC） （54% vs 18%; P=0.008） or in polymorphous carcinoma （PolyC） （54% vs 21% ; P=0.04）. NTYR staining was obviously more often found in TC than that in PolyC （72% vs 30% ; P=0.03）. There was a tendency towards a higher rate of iNOS staining when distant metastasis （pM） was present. In infiltrative TC, the presence of oxidative stress markers was not significantly correlated with histological grade, density of inflammation, the depth of infiltration （pT）, lymph nodes dissemination （pN） and pathological stages （pTNM）.CONCLUSION： The iNOS-oxidative pathway may play an important role in TC, but moderately in PolyC and DC. DNA oxidation and protein nitration occur in the three subtypes. Based on the significant differences of NTYR levels, TC and PolyC appear as two distinct subtypes.