ABSTRACT
Objective To investigate the long-term effects of xanthine oxidase inhibitor,oxypurinol on myocardial contractility of post-ischemic heart failure in mice,and explore the underlying mechanism. Methods One hundred and twenty SV120 mice were randomly assigned into myocardial infarction control group,sham operation group and Oxy treatment group.Post-ischemic heart failure were induced by left anterior descending coronary artery ligation in myocardial infarction control group and Oxy treatment group,and mice in Oxy treatment group and sham operation group were orally administered with 0.5 mmol/L Oxy each day.Nine to eleven months after treatment,echocardiography was performed in all groups.Trabeculae from the right ventricle of mice were dissected for assessment of changes in excitation-contraction coupling.Sarcomere length was measured by laser diffraction.Intracellular free Ca~(2+) concentration([Ca~(2+)]_I)was detected with fluorescent dye Fura-2,which was microinjected iontophoretically into cells. Steady-state force-[Ca~(2+)]_I was achieved by addition of ryanodine and increasing the stimulus frequency to induce tetanization,and the relationship between myocardial contractility and intracellular Ca~(2+) transients was analysed.Besides,Western blotting was performed to determine the oxidation of myofilament proteins. Results Long-term oral administration of oxypurinol significantly improved myocardial contraction function and reduced ventricular wall thickness.Programming of excitation-contraction coupling was significantly improved,and maximal Ca~(2+) activated force(F_(max))in steady-state wag also significantly increased.Western blotting revealed the oxidative modification of actin in mice of Oxy treatment group was significantly inhibited compared with that of myocardial infarction control group. Conclusion Long-term treatment with Oxy improves the cardiac contraction function and boosts the cardiac force dramatically in post-ischemia heart failure.The increase in contraction is the result of increased myofilament Ca~(2+) responsiveness.Thus,antioxidant oxypurinol,by preventing oxidative damage to contractile proteins,can augment contraction with little changes in[Ca~(2+)]_I,represents new class of inotropic agents with advantages of reducing Ca~(2+) overload,and offers new promises in management of heart failure in the future.
ABSTRACT
Objective To study whether the uremic toxins accumulated long-term in uremia patients may be involved in oxidation of protein by forming advanced oxidative protein products (AOPPs). Methods Malonylaldehyde (MDA), hippuric acid (HA) and p-cresol were used as the representatives of uremic toxins. Human albumin serum (HSA), plasma specimens from normal or uremia patients were incubated respectively with MDA (10 retool/L), HA (20 mmol/L) and p-cresol (10 retool/L) or PBS (20 retool/L, pH 7.4, as control groups) at 37℃ for 30 minutes or 24 hours, respectively. Those indices such as AOPPs, protein thiol groups (Pt-SH) and dityrosine were used as biomarkers of protein injury. High performance liquid chromatography (HPLC) was employed to identify the aggregation and cross-links of modified proteins. Results AOPPs levels in all groups containing poison compounds were significantly increased by 121.5%(P<0.05) compared to that in control groups. Uremic toxins also resulted in over 14.7% loss in Pt-SH (P< 0.05) and 119.2% increment in dityrosine, respectively (P<0.05). Meanwhile, the formation of HMW-AOPPs in a time-dependent manner was observed by HPLC and cross-linked protein levels were significantly increased by 148.45%～333.3% in comparison with control groups. Conclusion Uremic toxins can directly mediate the damage of proteins by inducing the formation of HMW- AOPPs in a time-dependent manner, which is also one of the mechanism of AOPPs production in vivo besides the activation of the myeloperoxidase-H2O2-Cl pathway.
ABSTRACT
Objective To study the effect of oxidative modification of hydrochlorous acid (HOCl) on human serum albumin (HSA) and the relationship between the AOPPs and HOCl-treated HSA. Methods Purified HSA (60 mg/ml) was treated with HOCl (0, 1, 5, 10, 20, 30, 40, 50 and 60 mmol/L). Size-exclusion chromatography was applied to estimate molecular weights of oxidized products of HSA by HOCl and spectrum scan from 190 nm -400 nm was performed to observe the spectrum characteristics of all variants of HSA. Results Major products of HSA after exposure to HOC1 were dimer and hexmer of HSA. The first-order process could be employed to describe the oxidative dynamics of monomer and dimer of HSA oxidized by HOCl. To AOPPs formation mediated by oxidant was identified as pseudo first-order reaction. However, formation hexmer was much in accordance with second-order reaction. Hexmer was also a major contributor to AOPPs in all types of modified HSA. Spectral analysis showed that red shift of absorbance maximum of polymers of HSA occurred, suggesting that a possibility that polymers of HSA were cross linked by tyrosine residues in protein. Conclusions Protein aggregation is primary consequence of HSA after its exposure to HOCl. Hexmer of HSA is the major contributor to AOPPs.
ABSTRACT
OBJECTIVE: This study was performed to compare the prooxidative activity stimulating the protein carbonyl formation by cephalosporins in the umbilical venous and placenta of preeclampsia with that of normal pregnancy. METHODS: Lipid peroxide levels in the umbilical venous plasma and placental tissue homogenates of normal pregnancy (n=12) and preeclampsia (n=12) were measured by thiobarbituric acid reaction. The basal protein carbonyl contents in the umbilical venous plasma and placental tissue homogenates of normal pregnancy (n=12) and preeclampsia (n=12) were determined by the 2,4-dinitrophenylhydrazine (DNPH) method. After samples of them were mixed and incubated up to 5 hours with 0.2 mL of 1 mM moxalactam or cephalothin, the protein carbonyl contents in them were measured by DNPH. RESULTS: Protein carbonyls formation by moxalactam and cephalothin in the umbilical venous plasma and of women with preeclampsia were significantly higher than that of women with normal pregnancy (8.5+/-2.0 vs. 6.6+/-1.4 nmol/mg protein, p<0.05, 7.6+/-1.6 vs. 6.2+/-1.2 nmol/mg protein, p<0.05). Protein carbonyls formation by moxalactam and cephalothin in the placental tissue homogenates of women with preeclampsia were significantly higher than that of women with normal pregnancy (17.6+/-5.3 vs. 13.0+/-4.2 nmol/mg protein, p<0.05, 16.1+/-5.2 vs. 12.5+/-4.4 nmol/mg protein, p<0.05). There were significant positive correlations between lipid peroxide and cephalosporins induced protein carbonyls levels of umbilical venous plasma, and placental tissue homogenates (p<0.01). CONCLUSION: These results suggest that increase in the prooxidative activity stimulating the oxidative modification of proteins in placenta may be involved in the pathogenesis of preecalmpsia.
Subject(s)
Female , Humans , Pregnancy , Cephalosporins , Cephalothin , Moxalactam , Placenta , Plasma , Pre-Eclampsia , Protein CarbonylationABSTRACT
Objective: To explore the mechanism of high incidence of cardiovascular diseases and the levels of plasma lipids and oxidized lowdensity lipoprotein(Ox-LDL) in patients with rheumatoid arthritis(RA).Methods: Fifty-five patients with RA(24 case of active type,31 non-active) and 60 healthy controls were randomly chosen.Plasma lipids and Ox-LDL levels were studied.All the data were subjected to statistical analysis.Results: Compared with the control,total cholesterol(TC),LDL cholesterol(LDL-C) and apolipoprotein B(apoB) levels were increased in patients with active RA,while TC,triglyceride(TG),LDL-C,apoAⅠ,B and Ox-LDL levels were elevated in those with non-active RA.Furthermore,plasma lipids and Ox-LDL level decreased in the active patients as compared with the non-active ones,while only the change of apoAⅠhad statistical significance.The erythrocyte sedimentation rate was found negatively related with TC,LDL-C,high-density lipoprotein cholesterol(HDL-C) and apoAⅠ,while C-reacting protein was found negatively related with LDL-C and HDL-C.Conclusion: Ox-LDL and plasma lipid levels were changed in RA patients.Inflammation may induce changes of lipoprotein and play an important role in atherosclerosis.
ABSTRACT
Objective: Oxidative modification of low density lipoprotein(LDL) plays an important role in the development of premature atherosclerosis in autoimmune disorders.Oxidized LDL(ox-LDL) reportedly forms stable complexes with ?2-glycoprotein I(?2-GPI),a major autoantigen for anticardiolipin antibodies,in circulation and the intima of atherosclerotic lesions. This study aims to investigate the serum ?2-GPI/ox-LDL concentration in Chinese patients with systemic lupus erythematosus(SLE),and clinical diagnostic value.Methods: The concentrations of ?2-GPI/ox-LDL complexes were analyzed in 47 SLE patients and 42 healthy controls by ELISA.Results: The serum ?2-GPI/ox-LDL concentrations were significantly higher in the SLE patients than in the controls(\U/ml vs\U/ml,P
ABSTRACT
BACKGROUND: The oxidative modification of lipids and the endothelial expression of adhesion molecules are key events in the pathogenesis of atherosclerosis. The appropriate antioxidants that protected and slowed the progression of the disease were reported. We measured the antioxidant enzyme activities and the levels of soluble cellular adhesion molecules in order to evaluate whether antioxidant vitamin supplementation affected the oxidative changes and the expression of cellular adhesion molecules. METHODS: Seventy-seven patients participated in a randomized, double blind, placebo-controlled trial. The test group (38 patients) was given antioxidant vitamin doses including a daily dose of vitamin C 500 mg, beta-carotene 15 mg, vitamin E 400 IUs, and selenium 50 microgram, The control group (44 patients) received placeboes for three months. We measured the vitamin serum levels, intercellular adhesion molecules-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin and activities of erythrocyte enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) before and at 3 months after supplementation. RESULTS: After supplementation, the serum vitamin levels increased significantly (P<0.05) and the activity of the erythrocyte SOD significantly increased by 0.85 unit/mg hemoglobin (P<0.05) in the test group. Soluble ICAM-1, VCAM-1 and E-selectin levels did not change significantly in the test group after supplementation. CONCLUSIONS: These results suggest that the antioxidant vitamin supplementation may affect erythrocyte SOD activity, but not soluble cellular adhesion molecule levels.
Subject(s)
Humans , Antioxidants , Ascorbic Acid , Atherosclerosis , beta Carotene , Catalase , E-Selectin , Erythrocytes , Glutathione Peroxidase , Intercellular Adhesion Molecule-1 , Selenium , Superoxide Dismutase , Vascular Cell Adhesion Molecule-1 , Vitamin E , VitaminsABSTRACT
AIM: To study the effects of oxidative modification lipoproteins on blood coagulation and fibrino (lysis) in vitro. METHODS: Normal human plasma VLDL, LDL and HDL, which were isolated by density gradient ultracentrifugation method, were oxidatively modified by Cu~(2+) and HOCl method. N-VLDL, Ox-VLDL, N-LDL, Ox-LDL, N-HDL, Ox-HDL were added to the reaction system which consisted of mixed fresh normal plasma respectively, prothrombin time (PT), activated partial thrombplastin time (APTT), plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA) and platelet aggregation were measured according to the direction of the kits. RESULTS: The relative electrophoretic mobility (REM), absorbance at 234nm and TBARS of oxidized VLDL, LDL and HDL mediated by HOCl or Cu~(2+) were significantly higher than that of the control group (P