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 radi...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）展开更多
Objective To find out whether dexamethasone induces an uncoupling of the endothelial nitric oxide synthase （eNOS）. Methods ＆ Results A major cause of eNOS uncoupling is a deficiency of its cofactor tetrahydrobiopte...Objective To find out whether dexamethasone induces an uncoupling of the endothelial nitric oxide synthase （eNOS）. Methods ＆ Results A major cause of eNOS uncoupling is a deficiency of its cofactor tetrahydrobiopterin （BH4）. Treatment of human EA.hy 926 endothelial cells with dexamethasone decreased mRNA and protein expression of both BH4-synthesizing enzymes： GTP cyclobydrolase I and dihydrofolate reductase. Consistently, a concentration- and time-dependent reduction of BH4, dihydrobiopterin （BH2） as well as BH4：BH2 ratio was observed in dexamethasone-treated cells. Surprisingly, no evidence for eNOS uncoupling was found. We then analyzed the expression and phosphorylation of the eNOS enzyme. Dexamethasone treatment led to a down-regulation of eNOS protein and a reduction of eNOS phosphorylation at serine 1177. A reduction of eNOS expression may lead to a relatively normal BH4： eNOS molar ratio in dexamethasone-treated cells. Because the BH4-eNOS stoichiometry rather than the absolute BH4 amount is the key determinant of eNOS functionality （i.e., coupled or uncoupled）, the down-regulation of eNOS may represent an explanation for the absence of eNOS uncoupling. Phosphorylation of eNOS at serine 1177 is needed for both the NO-producing activity of the coupled eNOS and the superoxide-producing activity of the uncoupled eNOS. Thus, a reduction of serine 1177 phosphorylation may render a potentially uncoupled eNOS hardly detectable. Conclusions Although dexamethasone reduces BH4 levels in endothelial cells, eNOS uncoupling is not evident. The reduction of NO production in dexamethasone-treated endothelial cells is mainly attributable to reduced eNOS expression and decreased eNOS phosphorylation at serine 1177.展开更多
Abstract Objectives To assess the incidence of tetrahydrobiopterin (BH4)deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese and evaluate clinical outcome and gene mutations in tetrahydrobi...Abstract Objectives To assess the incidence of tetrahydrobiopterin (BH4)deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese and evaluate clinical outcome and gene mutations in tetrahydrobiopterin deficient patients.Methods Urinary neopterin (N) and biopterin (B) was analyzed in 87 patients with hyperphenylalaninemia by high-performance liquid chromatography. Further combined loading tests with phenylalanine(Phe) (100*!mg/kg) and tetrahydrobiopterin (BH4) (7.5*!mg/kg) were performed in suspected patients with abnormal urinary pterin profiles. Gene mutation analysis was performed for patients with BH4 deficiency and their parents. BH4 deficient patients were treated with BH4 and neurotransmitter precursors after diagnosis. Blood phenylalanine levels, clinical symptoms and mental development were followed up.Results Eleven patients were diagnosed as having BH4 deficiency caused by 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The incidence of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese was 10%. Combined loading tests with phenylalanine and oral BH4 were done in 4 of 11 patients and their phenylalanine levels were decreased to normal 4-6h after BH4 administration. Four different mutations (P87S, N52S, D96N and G144R) in the PTPS gene were detected in 5 families. Five PTPS-deficient patients were treated with synthetic BH4, neurotransmitter precursors (L-dopa plus carbidopa, and 5-hydroxytryptophan). They had satisfactory physical and mental development after treatment. One patient with partial PTPS deficiency had normal growth and mental development without treatment. Conclusions Our results emphasize that screening for BH4 deficiency should be carried out in all patients with hyperphenylalaninemia in order to minimize the misdiagnosis. Patients with BH4 deficiency should be treated early with BH4 and a combination of neurotransmitter precursors.展开更多
Background：Tetrahydrobiopterin （BH4） is an essential cofactor of nitric oxide synthases （NOSs） for the synthesis of nitric oxide （NO）.BH4 therapy can reverse the disease-related redox disequilibrium observed wi...Background：Tetrahydrobiopterin （BH4） is an essential cofactor of nitric oxide synthases （NOSs） for the synthesis of nitric oxide （NO）.BH4 therapy can reverse the disease-related redox disequilibrium observed with BH4 deficiency.However,whether BH4 exerts a protective effect against radiation-induced damage to cardiomyocytes remains unknown.Methods：Clonogenic assays were performed to determine the effects of X-ray on H9c2 cells with or without BH4 treatment.The contents of lactate dehydrogenase （LDH）,superoxide dismutase （SOD）,and malondialdehyde （MDA） in H9c2 cells were measured to investigate oxidative stress levels.The cell cycle undergoing radiation with or without BH4 treatment was detected using flow cytometry.The expression levels of proteins in the phosphatidylinositol 3 kinase （PI3K）/protein kinase B （AKT）/P53 signaling pathway,inducible NOS （iNOS）,and endothelial NOS （eNOS） were examined using Western blotting.Results：X-ray radiation significantly inhibited the growth of H9c2 cells in a dose-dependent manner,whereas BH4 treatment significantly reduced the X-ray radiation-induced growth inhibition （control group vs.X-ray groups,respectively,P 〈 0.0 l）.X-ray radiation induced LDH release,apoptosis,and G0/G 1 peak accumulation,significantly increasing the level of MDA and the production of NO,and decreased the level of SOD （control group vs.X-ray groups,respectively,P 〈 0.05 or P 〈 0.01）.By contrast,BH4 treatment can significantly reverse these processes （BH4 treatment groups vs.X-ray groups,P 〈 0.05 or P 〈 0.01）.BH4 reversed the X-ray radiation-induced expression alterations ofapoptosis-related molecules,including B-cell lymphoma-2 （Bcl-2）,Bcl-2 associated X protein,and caspase-3,and molecules of the PI3K/Akt/P53 signaling pathway.BH4 enhanced the production of NO in 2 Gy and 4 Gy radiated groups by upregulating eNOS protein expression and downregulating iNOS protein expression.Conclusions：BH4 treatment can protect against X-ray-induced cardiomyocyte injury,possibly by recoupling eNOS rather than iNOS.BH4 treatment also decreased oxidative stress in radiated H9c2 cells.展开更多
Objective To investigate the effect and mechanism of tetrahydrobiopterin(BH4)on the angiogenesis in hepatocellular carcinoma(HCC).Methods BALB/c-nu mice were subcutaneously injected with Hep G-2 cells and randomly div...Objective To investigate the effect and mechanism of tetrahydrobiopterin(BH4)on the angiogenesis in hepatocellular carcinoma(HCC).Methods BALB/c-nu mice were subcutaneously injected with Hep G-2 cells and randomly divided into control and BH4 groups.The展开更多
Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control...Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.展开更多
文摘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）
文摘Objective To find out whether dexamethasone induces an uncoupling of the endothelial nitric oxide synthase （eNOS）. Methods ＆ Results A major cause of eNOS uncoupling is a deficiency of its cofactor tetrahydrobiopterin （BH4）. Treatment of human EA.hy 926 endothelial cells with dexamethasone decreased mRNA and protein expression of both BH4-synthesizing enzymes： GTP cyclobydrolase I and dihydrofolate reductase. Consistently, a concentration- and time-dependent reduction of BH4, dihydrobiopterin （BH2） as well as BH4：BH2 ratio was observed in dexamethasone-treated cells. Surprisingly, no evidence for eNOS uncoupling was found. We then analyzed the expression and phosphorylation of the eNOS enzyme. Dexamethasone treatment led to a down-regulation of eNOS protein and a reduction of eNOS phosphorylation at serine 1177. A reduction of eNOS expression may lead to a relatively normal BH4： eNOS molar ratio in dexamethasone-treated cells. Because the BH4-eNOS stoichiometry rather than the absolute BH4 amount is the key determinant of eNOS functionality （i.e., coupled or uncoupled）, the down-regulation of eNOS may represent an explanation for the absence of eNOS uncoupling. Phosphorylation of eNOS at serine 1177 is needed for both the NO-producing activity of the coupled eNOS and the superoxide-producing activity of the uncoupled eNOS. Thus, a reduction of serine 1177 phosphorylation may render a potentially uncoupled eNOS hardly detectable. Conclusions Although dexamethasone reduces BH4 levels in endothelial cells, eNOS uncoupling is not evident. The reduction of NO production in dexamethasone-treated endothelial cells is mainly attributable to reduced eNOS expression and decreased eNOS phosphorylation at serine 1177.
基金theShanghaiScientificandTechnologyCommittee (No .95 41190 3)
文摘Abstract Objectives To assess the incidence of tetrahydrobiopterin (BH4)deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese and evaluate clinical outcome and gene mutations in tetrahydrobiopterin deficient patients.Methods Urinary neopterin (N) and biopterin (B) was analyzed in 87 patients with hyperphenylalaninemia by high-performance liquid chromatography. Further combined loading tests with phenylalanine(Phe) (100*!mg/kg) and tetrahydrobiopterin (BH4) (7.5*!mg/kg) were performed in suspected patients with abnormal urinary pterin profiles. Gene mutation analysis was performed for patients with BH4 deficiency and their parents. BH4 deficient patients were treated with BH4 and neurotransmitter precursors after diagnosis. Blood phenylalanine levels, clinical symptoms and mental development were followed up.Results Eleven patients were diagnosed as having BH4 deficiency caused by 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The incidence of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese was 10%. Combined loading tests with phenylalanine and oral BH4 were done in 4 of 11 patients and their phenylalanine levels were decreased to normal 4-6h after BH4 administration. Four different mutations (P87S, N52S, D96N and G144R) in the PTPS gene were detected in 5 families. Five PTPS-deficient patients were treated with synthetic BH4, neurotransmitter precursors (L-dopa plus carbidopa, and 5-hydroxytryptophan). They had satisfactory physical and mental development after treatment. One patient with partial PTPS deficiency had normal growth and mental development without treatment. Conclusions Our results emphasize that screening for BH4 deficiency should be carried out in all patients with hyperphenylalaninemia in order to minimize the misdiagnosis. Patients with BH4 deficiency should be treated early with BH4 and a combination of neurotransmitter precursors.
基金This work was supported by the National Natural Science Foundation of China （No. 81270332）, and Gansu Province Health Industry Scientific Research Plan （No. GSWSKY-2014-33）.
文摘Background：Tetrahydrobiopterin （BH4） is an essential cofactor of nitric oxide synthases （NOSs） for the synthesis of nitric oxide （NO）.BH4 therapy can reverse the disease-related redox disequilibrium observed with BH4 deficiency.However,whether BH4 exerts a protective effect against radiation-induced damage to cardiomyocytes remains unknown.Methods：Clonogenic assays were performed to determine the effects of X-ray on H9c2 cells with or without BH4 treatment.The contents of lactate dehydrogenase （LDH）,superoxide dismutase （SOD）,and malondialdehyde （MDA） in H9c2 cells were measured to investigate oxidative stress levels.The cell cycle undergoing radiation with or without BH4 treatment was detected using flow cytometry.The expression levels of proteins in the phosphatidylinositol 3 kinase （PI3K）/protein kinase B （AKT）/P53 signaling pathway,inducible NOS （iNOS）,and endothelial NOS （eNOS） were examined using Western blotting.Results：X-ray radiation significantly inhibited the growth of H9c2 cells in a dose-dependent manner,whereas BH4 treatment significantly reduced the X-ray radiation-induced growth inhibition （control group vs.X-ray groups,respectively,P 〈 0.0 l）.X-ray radiation induced LDH release,apoptosis,and G0/G 1 peak accumulation,significantly increasing the level of MDA and the production of NO,and decreased the level of SOD （control group vs.X-ray groups,respectively,P 〈 0.05 or P 〈 0.01）.By contrast,BH4 treatment can significantly reverse these processes （BH4 treatment groups vs.X-ray groups,P 〈 0.05 or P 〈 0.01）.BH4 reversed the X-ray radiation-induced expression alterations ofapoptosis-related molecules,including B-cell lymphoma-2 （Bcl-2）,Bcl-2 associated X protein,and caspase-3,and molecules of the PI3K/Akt/P53 signaling pathway.BH4 enhanced the production of NO in 2 Gy and 4 Gy radiated groups by upregulating eNOS protein expression and downregulating iNOS protein expression.Conclusions：BH4 treatment can protect against X-ray-induced cardiomyocyte injury,possibly by recoupling eNOS rather than iNOS.BH4 treatment also decreased oxidative stress in radiated H9c2 cells.
文摘Objective To investigate the effect and mechanism of tetrahydrobiopterin(BH4)on the angiogenesis in hepatocellular carcinoma(HCC).Methods BALB/c-nu mice were subcutaneously injected with Hep G-2 cells and randomly divided into control and BH4 groups.The
基金funded by the Universiti Tunku Abdul Rahman Research fund(IPSR/RMC/UTARRF/2019-C2/L08)。
文摘Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.
