The molecular mechanisms underlying the reduction of LDL apoB-100 by ezetimibe plus simvastatin

The combination of ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein (NPC1L1), and an HMG-CoA reductase inhibitor decreases cholesterol absorption and synthesis. In clinical trials, ezetimibe plus simvastatin produces greater LDL-cholesterol reductions than does monotherapy. The molecular mechanism for this enhanced efficacy has not been defined. Apolipoprotein B-100 (apoB-100) kinetics were determined in miniature pigs treated with ezetimibe (0.1 mg/kg/day), ezetimibe plus simvastatin (10 mg/kg/day), or placebo (n = 7/group). Ezetimibe decreased cholesterol absorption (-79%) and plasma phytosterols (-91%), which were not affected further by simvastatin. Ezetimibe increased plasma lathosterol (+65%), which was prevented by addition of simvastatin. The combination decreased total cholesterol (-35%) and LDL-cholesterol (-47%). VLDL apoB pool size decreased 26%, due to a 35% decrease in VLDL apoB production. LDL apoB pool size decreased 34% due to an 81% increase in the fractional catabolic rate, both of which were significantly greater than monotherapy. Combination treatment decreased hepatic microsomal cholesterol (-29%) and cholesteryl ester (-65%) and increased LDL receptor (LDLR) expression by 240%. The combination increased NPC1L1 expression in liver and intestine, consistent with increased SREBP2 expression. Ezetimibe plus simvastatin decreases VLDL and LDL apoB-100 concentrations through reduced VLDL production and upregulation of LDLR-mediated LDL clearance.     

Cytotoxicity of Malondialdehyde and Cytoprotective Effects of Taurine <Emphasis Type="Italic">via</Emphasis> Oxidative Stress and PGC-1α Signal Pathway in C2C12 Cells

One of the end-products of ROS-induced peroxidation, malondialdehyde (MDA), induces the cross-links in proteins, which leads to perturbation of the physiological functions of cells and contributes to abnormal biological regulation and various disorders. Taurine (2-aminoethanesulfonic acid, Tau) aids in adjusting normal physiological functions to confer stress resistance. The protective effects of Tau against MDA stress in vitro or in vivo were reported previously. In this study, we had investigated the protective effects of taurine on viability, oxidative stress levels and mitochondrial biogenesis in mouse muscle C2C12 cells undergoing MDA induced stress. We show that the treatment with 100 μM MDA leads to increase in cell oxidative stress levels, inhibition of mitochondrial biogenesis and the reduction of the cell survival rates. The pretreatment with 0.1 μM taurine reduced MDA-induced death rate via inhibition of oxidative stress, restoration of mitochondrial functions of the mitochondrial membrane potential (MMP) and ATP production. In MDA stress, the pre-treatment with 0.1 μM taurine leads to upregulation of the factors of mitochondrial biogenesis. These observations suggest that the cytoprotective effects of taurine may be due to an induction of mitochondrial biogenesis.     

Economic evaluation of ezetimibe combined with simvastatin for the treatment of primary hypercholesterolaemia

Objective

This study aims to assess the cost-effectiveness of ezetimibe plus simvastatin (E/S) versus atorvastatin or simvastatin monotherapy as second-line treatment of primary hypercholesterolaemia from the Dutch healthcare perspective.

Methods

The evaluation used a Markov model and patient data from the Dutch EASEGO study in which patients failing to reach goal low-density lipoprotein cholesterol levels on atorvastatin 10 mg or simvastatin 20 mg had their dose doubled or switched to ezetimibe 10 mg plus generic simvastatin 20 mg (E10/S20). The second scenario, based on Dutch guidelines, switched patients from simvastatin 40 mg to atorvastatin 40 mg, or ezetimibe 10 mg was added to simvastatin 40 mg (E10/S40). The key effectiveness input measure was change in total cholesterol/high-density lipoprotein ratio obtained from the EASEGO study. In conformity with published studies linking reduced lipid levels to reduced risk of cardiovascular events, the present model assumed that a lipid decrease with ezetimibe may be a signal for reduced risk of cardiovascular events. Model parameters were derived from published literature. Sensitivity analyses were performed for the key parameters.

Results

In the EASEGO scenario, incremental cost-effectiveness ratio for E10/S20 was €3497/quality-adjusted life-years (QALY) vs atorvastatin 20 mg and €26,417/QALY vs simvastatin 40 mg. In the Dutch guidelines scenario, E10/S40 was dominant (more effective and cost-saving) vs atorvastatin 40 mg. Varying model inputs had limited impact on the cost-effectiveness of E/S.

Conclusions

The analysis showed the cost-effectiveness of E/S versus atorvastatin 20 mg or simvastatin 40 mg (EASEGO scenario) at a threshold of €30,000/QALY and vs atorvastatin 40 mg was dominant (Dutch guidelines). Thus, E/S seems a valuable cost-effective second-line treatment option for patients not attaining lipid treatment goals.     

Changes in cholesterol absorption and cholesterol synthesis caused by ezetimibe and/or simvastatin in men

This study evaluates changes in cholesterol balance in hypercholesterolemic subjects following treatment with an inhibitor of cholesterol absorption or cholesterol synthesis or coadministration of both agents. This was a randomized, double blind, placebo-controlled, four-period crossover study to evaluate the effects of coadministering 10 mg ezetimibe with 20 mg simvastatin (ezetimibe/simvastatin) on cholesterol absorption and synthesis relative to either drug alone or placebo in 41 subjects. Each treatment period lasted 7 weeks. Ezetimibe and ezetimibe/simvastatin decreased fractional cholesterol absorption by 65% and 59%, respectively (P < 0.001 for both relative to placebo). Simvastatin did not significantly affect cholesterol absorption. Ezetimibe and ezetimibe/simvastatin increased fecal sterol excretion (corrected for dietary cholesterol), which also represents net steady state cholesterol synthesis, by 109% and 79%, respectively (P < 0.001). Ezetimibe, simvastatin, and ezetimibe/simvastatin decreased plasma LDL-cholesterol by 20, 38, and 55%, respectively. The coadministered therapy was well tolerated. The decreases in net cholesterol synthesis and increased fecal sterol excretion yielded nearly additive reductions in LDL-cholesterol for the coadministration of ezetimibe and simvastatin.     

VAP II analysis of lipoprotein subclasses in mixed hyperlipidemic patients on treatment with ezetimibe/simvastatin and fenofibrate

This analysis evaluates the effects on lipoprotein subfractions and LDL particle size of ezetimibe/simvastatin with or without coadministration of fenofibrate in patients with mixed hyperlipidemia. This multicenter, double-blind, placebo-controlled, parallel-group study included 611 patients aged 18-79 years randomized in 1:3:3:3 ratios to one of four 12 week treatment groups: placebo; ezetimibe/simvastatin 10/20 mg/day; fenofibrate 160 mg/day; or ezetimibe/simvastatin 10/20 mg/day + fenofibrate 160 mg/day. At baseline and study endpoint, cholesterol associated with VLDL, intermediate density lipoprotein (IDL), LDL, and HDL subfractions was quantified using the Vertical Auto Profile II method. LDL particle size was determined using segmented gradient gel electrophoresis. Whereas fenofibrate reduced cholesterol mass within VLDL and IDL, and shifted cholesterol from dense LDL subfractions into the more buoyant subfractions and HDL, ezetimibe/simvastatin reduced cholesterol mass within all apolipoprotein B-containing particles without significantly shifting the LDL particle distribution profile. When administered in combination, the effects of the drugs were complementary, with more-pronounced reductions in VLDL, IDL, and LDL, preferential loss of more-dense LDL subfractions, and increased HDL, although the effects on most lipoprotein subfractions were not additive. Thus, ezetimibe/simvastatin + fenofibrate produced favorable effects on atherogenic lipoprotein subclasses in patients with mixed hyperlipidemia.     

Inhibition of cholesterol absorption by the combination of dietary plant sterols and ezetimibe: effects on plasma lipid levels

Consumption of plant sterols and treatment with ezetimibe both reduce cholesterol absorption in the intestine. However, the mechanism of action differs between the two treatments, and the consequences of combination treatment are unknown. Therefore, we performed a double-blind, placebo-controlled, crossover study for the plant sterol component with open-label ezetimibe treatment. Forty mildly hypercholesterolemic subjects were randomized to the following treatments for 4 weeks each: 10 mg/day ezetimibe combined with 25 g/day control spread; 10 mg/day ezetimibe combined with 25 g/day spread containing 2.0 g of plant sterols; 25 g/day spread containing 2.0 g of plant sterols; and placebo treatment consisting of 25 g/day control spread. Combination treatment of plant sterols and ezetimibe reduced low density lipoprotein cholesterol (LDL-C) by 1.06 mmol/l (25.2%; P < 0.001) compared with 0.23 mmol/l (4.7%; P = 0.006) with plant sterols and 0.94 mmol/l (22.2%; P < 0.001) with ezetimibe monotherapy. LDL-C reduction conferred by the combination treatment did not differ significantly from ezetimibe monotherapy (-0.12 mmol/l or -3.5%; P = 0.13). Additionally, the plasma lathosterol-to-cholesterol ratio increased with all treatments. Sitosterol and campesterol ratios increased after plant sterol treatment and decreased upon ezetimibe and combination therapy. Our results indicate that the combination of plant sterols and ezetimibe has no therapeutic benefit over ezetimibe monotherapy in subjects with mild hypercholesterolemia.     

Effects of ezetimibe and simvastatin on apolipoprotein B metabolism in males with mixed hyperlipidemia

Sixteen hyperlipidemic men were enrolled in a randomized, placebo-controlled, double-blind, cross-over study to evaluate the effect of ezetimibe 10 mg and simvastatin 40 mg, coadministered and alone, on the in vivo kinetics of apolipoprotein (apo) B-48 and B-100 in humans. Subjects underwent a primed-constant infusion of a stable isotope in the fed state. The coadministration of simvastatin and ezetimibe significantly reduced plasma concentrations of cholesterol (−43.0%), LDL-C (−53.6%), and triglycerides (−44.0%). Triglyceride-rich lipoproteins (TRL) apoB-48 pool size (PS) was significantly decreased (−48.9%) following combination therapy mainly through a significant reduction in TRL apoB-48 production rate (PR) (−38.0%). The fractional catabolic rate (FCR) of VLDL and LDL apoB-100 were significantly increased with all treatment modalities compared with placebo, leading to a significant reduction in the PS of these fractions. We also observed a positive correlation between changes in TRL apoB-48 PS and changes in TRL apoB-48 PR (r = 0.85; P < 0.0001) with combination therapy. Our results indicate that treatment with simvastatin plus ezetimibe is effective in reducing plasma TRL apoB-48 levels and that this effect is most likely mediated by a reduction in the intestinal secretion of TRL apoB-48. Our study also indicated that the reduction in LDL-C concentration following combination therapy is mainly driven by an increase in FCR of apoB-100 containing lipoproteins.     

Cadmium-induced oxidative stress and DNA damage in kidney of pregnant female rats

In the present study, we have investigated the influence of sub-acute treatment with cadmium (Cd) on some parameters indicative of oxidative stress and DNA damage in tissues of pregnant female rats. Pregnant female rats (n=6) were injected subcutaneously, daily with a dose of cadmium chloride of 3 mg/kg body weight (b.w.) from day 6 to day 19 of pregnancy, and they were allowed to deliver normally. MDA level and GPx, CAT and SOD activities were used as markers of oxidative stress in liver and kidney. The 8-oxo-dG level was measured by the HPLC-EC system. Cd treatment increased MDA (+116%, p<0.01) in kidney. Moreover, Cd treatment also decreased CuZn-SOD (-11%, p<0.05) and GSH level (-52%, p<0.05) in kidney. Treated rats displayed an increase of the liver metallothionein (MT) level. Induction of MT in liver was probably implicated in the detoxification of Cd. The high level of Cd (3 mg/kg) used in the present study is partially neutralized by MT in liver, whereas the free fraction could be implicated in the oxidative stress and DNA oxidation observed in kidney. Cd treatment failed to alter 8-oxodGuo, indicating the absence of DNA oxidation in liver; by contrast, the same treatment increased the 8-oxodGuo level (+51%, p<0.05) in the kidney of pregnant female rats, indicating an oxidative stress associated with DNA damage only in kidney.     

Antioxidant effect of simvastatin is not enhanced by its association with alpha-tocopherol in hypercholesterolemic patients

Among the pleiotropic effects of statins, their antioxidant action may be involved in their protective effects. Thus, we investigated the antioxidant effect of simvastatin, associated or not with alpha-tocopherol, on levels of electronegative low-density lipoprotein (LDL-), nitrotyrosine, thiols (homocysteine, glutathione, cysteine, methionine), and lipid-soluble antioxidants in blood plasma of hypercholesterolemic subjects. In this study, 25 hypercholesterolemic subjects were treated for 2 months with simvastatin (20 mg/day) and with simvastatin (20 mg/day) + alpha-tocopherol (400 IU/day). Concentrations of thiols were determined by high-performance capillary electrophoresis-laser-induced fluorescene. Lipid-soluble antioxidants were determined by HPLC, and LDL-, and nitrotyrosine by ELISA. Simvastatin, independent of its association with alpha-tocopherol, reduced plasma concentrations of LDL-, nitrotyrosine, total cholesterol, and LDL cholesterol and the LDL cholesterol/HDL cholesterol ratio. Neither simvastatin nor simvastatin plus alpha-tocopherol altered plasma levels of the thiols analyzed. alpha-Tocopherol did not change the antioxidant effect of simvastatin on the levels of LDL- and nitrotyrosine in hypercholesterolemic subjects. The reduction of LDL- and nitrotyrosine by simvastatin seems to be related to the pleiotropic effects of this statin, and it may have an important protective effect against endothelial dysfunction and atherosclerosis.     

Chronic administration of pioglitazone attenuates intracerebroventricular streptozotocin induced-memory impairment in rats

Memory impairment induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) in rats is associated with impaired brain glucose and energy metabolism, oxidative stress and impaired cholinergic neurotransmission. Treatment with antioxidants and cholinergic agonists has been reported to produce beneficial effect in this model. However, no reports are available on drugs that improve glucose utilization and metabolism. In the present study, we evaluated the effects of pioglitazone on cognitive performance, oxidative stress and glucose utilization in ICV STZ injected rats (3 mg/kg, on day 1 and 3). Pioglitazone (10 and 30 mg/kg) was administered per oral (p.o.) for 14 days, starting 5 days prior to STZ injection. Cognitive performance was assessed using step-through passive avoidance and Morris water maze task. Malondialdehyde (MDA) and glutathione levels in brain were estimated as parameters of oxidative stress. Glucose utilization by brain was assessed as the amount of glucose consumed from the media by the brain. ICV STZ injected rats showed a severe deficit in learning and memory associated with increased MDA levels (+67.5%), decreased glutathione levels (-29.2%) and impaired cerebral glucose utilization (-44.4%). In contrast pioglitazone treatment improved cognitive performance, lowered oxidative stress and improved cerebral glucose utilization in ICV STZ rats. The present study demonstrates the beneficial effects of pioglitazone in the ICV STZ induced cognitive deficits, which can be exploited for the dementia associated with diabetes and age-related neurodegenerative disorder, where oxidative stress and impaired glucose and energy metabolism are involved.     

Combination of carvacrol with simvastatin improves the lipid‐lowering efficacy and alleviates simvastatin side effects

The present investigation was designed to examine the possible additive hypolipidemic effect of carvacrol (CARV) in combination with simvastatin (SIM) on poloxamer 407 (P407)‐induced hyperlipidemia. Rats were injected with P407, (500 mg/ kg; i.p.), twice a week, for 30 days. Treatment was carried out by administration of SIM (20 mg/kg/day; p.o.) or CARV (50 mg/kg/day; p.o.) or combination of them. Treatment with CARV significantly decreased total cholesterol, triglycerides, low‐density lipoprotein, atherogenic index, leptin, and increased high‐density lipoprotein and adiponectin. Moreover, CARV potentiated the hypolipidemic effect of SIM. Both SIM and CARV alleviated the oxidative stress induced by P407. Interestingly, CARV, when combined with SIM, significantly ameliorated SIM‐induced liver and muscle injury by reducing the level of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and myoglobin and restoring the normal histological picture of both liver and muscle as well as apoptosis.     

Erythrocyte antioxidant enzymes in hypertensive patients receiving lisinopril monotherapy or combined lisinopril plus simvastatin therapy

Statins and angiotensin-converting enzyme (ACE) inhibitors have beneficial impact on the serum cholesterol and blood pressure. It is supposed that statins and ACE inhibitors may modify the antioxidative status in erythrocytes. The study objective was to compare the effects of two treatments, lisinopril alone versus lisinopril plus simvastatin, on erythrocyte antioxidant enzyme activities. The study involved 32 patients with arterial hypertension, their initial serum total cholesterol, LDL-cholesterol and triglycerides were within the normal range. Patients of two groups, each of 16 subjects, were treated with lisinopril (10 mg/day) or with lisinopril (10 mg/day) plus simvastatin (20 mg/day). Before and after the ambulatory therapy for 3 and 6 months, activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR) were determined in purified erythrocytes. All treated patients had significantly higher catalase activity (by 79.3–106.5%, p < 0.0001) and significantly lower GPx activity (by 20.7–30.6%, p < 0.001) as compared to the baselines. The same results were obtained in both groups (lisinopril and lisinopril + simvastatin), after both periods (3 and 6 month) of treatments. SOD activity increased only in the lisinopril group and only after 6 months (p = 0.0345). No changes of GR activity were observed under all conditions studied. Thus, the lisinopril monotherapy and combined lisinopril plus simvastatin therapy exhibit specific, pronounced and equipotent effects on antioxidant enzymes in human erythrocytes. Peroral administration of lisinopril or lisinopril plus simvastatin may protect erythrocytes and other tissues against oxidative damage.     

Statin therapy lowers muscle sympathetic nerve activity and oxidative stress in patients with heart failure

Despite standard drug therapy, sympathetic nerve activity (SNA) remains high in heart failure (HF) patients making the sympathetic nervous system a primary drug target in the treatment of HF. Studies in rabbits with pacing-induced HF have demonstrated that statins reduce resting SNA, in part, due to reductions in reactive oxygen species (ROS). Whether these findings can be extended to the clinical setting of human HF remains unclear. We first performed a study in seven statin-na?ve HF patients (56 ± 2 yr; ejection fraction: 31 ± 4%) to determine if 1 mo of simvastatin (40 mg/day) reduces muscle SNA (MSNA). Next, to control for possible placebo effects and determine the effect of simvastatin on ROS, a double-blinded, placebo-controlled crossover design study was performed in six additional HF patients (51 ± 3 yr; ejection fraction: 22 ± 4%), and MSNA, ROS, and superoxide were measured. We tested the hypothesis that statin therapy decreases resting MSNA in HF patients and this would be associated with reductions in ROS. In study 1, simvastatin reduced resting MSNA (75 ± 5 baseline vs. 65 ± 5 statin bursts/100 heartbeats; P < 0.05). Likewise, in study 2, simvastatin also decreased resting MSNA (59 ± 5 placebo vs. 45 ± 6 statin bursts/100 heartbeats; P < 0.05). In addition, statin therapy significantly reduced total ROS and superoxide. As expected, cholesterol was reduced after simvastatin. Collectively, these findings indicate that short-term statin therapy concomitantly reduces resting MSNA and total ROS and superoxide in HF patients. Thus, in addition to lowering cholesterol, statins may also be beneficial in reducing sympathetic overactivity and oxidative stress in HF patients.     

Increasing intracellular cAMP and cGMP inhibits cadmium-induced oxidative stress in rat submandibular saliva

The effect of cadmium on induction of oxidative stress in rat submandibular saliva and protective role of increasing intracellular cAMP and cGMP by use of specific phosphodiesterase inhibitors, theophylline and sildenafil were investigated. Pure submandibular saliva was collected intraorally by micro polyethylene cannula from anaesthetized rats using pilocarpine as secretagogue. Acute administration of cadmium (10 mg/kg) caused significant oxidative stress by increasing lipid peroxidation by-products (thiobarbituric reactive substances, TBARS) and decreasing total thiols and total antioxidant power of the saliva. Concurrent therapy of rats by theophylline (25 mg/kg) and sildenafil (5 mg/kg) prevented cadmium-induced oxidative stress in saliva. Theophylline and sildenafil inhibited cadmium-induced increase in lipid peroxidation and decrease in total thiols and antioxidant power. It is concluded that cadmium administration results in oxidative stress in rat submandibular saliva, which can be protected by concurrent administration of specific cyclic nucleotide phosphodiesterase inhibitors.     

Oxidative stress of liver in hamsters infected with Leishmania (L.) chagasi

Oxidative stress as a mediator of hepatic tissue damage concurrent with Leishmania (L.) chagasi infection was investigated. Chemiluminescence in liver supernatant of hamsters infected with Leishmania (L.) chagasi showed a ratio of 1.53/ mg protein and 2.10/liver weight 90 days after infection when compared with the control. The malondialdehyde (MDA) levels also increased significantly both with and without addition of Fe3+/ascorbic acid in the reaction mixture, with a ratio of 2.12 and 1.55/mg protein or 2.91 and 2.12/liver weight, respectively. The parasite burden in the spleen, as a measure of infection severity, was 9.1+/-1.33 x 10(8) parasites/organ. On the 10th day of infection, the chemiluminescence also was significantly higher in infected hamsters than in the controls (ratio = 1.36/mg protein or 1.34/liver weight); however, the MDA levels were not different from those of controls. After 90 days of infection, significant correlations were observed between chemiluminescence and MDA concentration with and without the presence of Fe3+/ascorbic acid (r = 0.54, P = 0.0001; r = 0.56, P = 0.0001; respectively). The high infection/control ratio of both chemiluminescence and MDA concentration and the significant correlation between those events strongly indicate the occurrence of oxidative stress and lipid peroxidation as a mechanism of liver damage in cases of chronic infection by L. chagasi. The significant increase in chemiluminescence at 10 days of infection demonstrates that oxidative stress occurs very early, first consuming the antioxidants and then inducing lipid peroxidative damage later in the chronic stage of this disease.     

Effects of Lithium and Lamotrigine on Oxidative–Nitrosative Stress and Spatial Learning Deficit After Global Cerebral Ischemia

Lithium (Li) and lamotrigine (LTG) have neuroprotective properties. However, the exact therapeutic mechanisms of these drugs have not been well understood. We investigated the antioxidant properties of Li (40 and 80 mg/kg/day) and LTG (20 and 40 mg/kg/day) in a rat model of global cerebral ischemia based on permanent bilateral occlusion of the common carotid arteries (BCAO). Nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), glutathione reductase (GSH-R), catalase (CAT) and superoxide dismutase (SOD) levels were measured as an indicator of oxidative–nitrosative stress in both prefrontal cortex (PFC) and hippocampus after 28 days of treatment. The spatial learning disability was also assessed at the end of the study by Morris water maze (MWM) test. All oxidative–nitrosative parameters were found to be higher in the groups under treatment than in sham. Both drugs caused a decrease in PFC NO and MDA elevation, meanwhile the increase in GSH, GSH-R, CAT and SOD levels was significantly more evident in treated groups. We also found higher PFC GSH-R and hippocampal SOD levels in BCAO + Li (80 mg/day) treated group when compared with BCAO + LTG 40 mg/day. MWM test data showed a similar increase in spatial learning ability in all groups under treatment. We found no other statistical difference in comparison of treated groups with different dosages. Our findings suggested that Li and LTG treatments may decrease spatial learning memory deficits accompanied by lower oxidative–nitrosative stress in global cerebral ischemia. Both drugs may have potential benefits for the treatment of vascular dementia in clinical practice.     

Unexpected effect of urate on hydrogen peroxide-induced oxidative damage in embryonic chicken cardiac cells

Uric acid (UA) is a potent scavenger of oxidants in most mammalian and avian species. The aim of this study was to obtain more comprehensive information regarding the relationship between different concentrations of UA and oxidative balance in chicken cardiac cells. First, oxidative damage parameters were measured in chicken cardiac cells treated with different concentrations of UA. UA concentrations within the normal physiological range had no effect, while treatment with a high level of UA, i.e. 1200?μM, increased the malondialdehyde (MDA) and protein carbonyl contents, decreased the superoxide dismutase (SOD) and catalase (CAT) activities, and had no effect on glutathione (GSH) in cardiac muscle cells. In addition, the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was stimulated in cells treated with 1200?μM UA. Next, the role of UA in protecting cells from oxidative damage was investigated in hydrogen peroxide (H₂O₂)-damaged chicken cardiac cells. Treatment with UA within the normal physiological range reduced the increased MDA and protein carbonyl contents and SOD enzymatic activity induced by H₂O₂ exposure to some extent and inhibited reactive oxygen species (ROS) formation, presumably as a result of the Nrf2 pathway activation in H₂O₂-damaged cells. By contrast, the MDA and protein carbonyl contents were increased, SOD enzymatic activity was depressed, and the Nrf2 pathway was further down-regulated in H₂O₂-damaged cells treated with 1200?μM UA. In conclusion, the results indicated that physiological UA concentration partially alleviated oxidative stress in chicken cardiac muscle cells treated with H₂O₂. However, supraphysiological UA concentrations promoted oxidative damages directly in primary cultured chicken cardiac muscle cells and aggravated oxidative stress in H₂O₂-damaged cells.     

Mycophenolate mofetil and curcumin provide comparable therapeutic benefit in experimental chronic kidney disease: role of Nrf2-Keap1 and renal dopamine pathways

Increased oxidative stress and inflammation have an important role in the pathophysiology of chronic kidney disease (CKD). On the other hand, more affordable therapeutic alternatives for treating this disease are urgently needed. Therefore, we compared the therapeutic efficacy of curcumin and mycophenolate mofetil (MMF) in 5/6 nephrectomy (5/6 Nx) model of CKD. Also, we evaluated whether both compounds provide benefit through the preservation of similar antioxidant mechanisms. Four groups of male Wistar were studied over a period of 4 wk. Control sham group (n=?12), 5/6 Nx (n?=?12), 5/6 Nx?+?MMF (30?mg/k BW/day, n?=?11) and 5/6 Nx?+?Curcumin (120?mg/k BW/day, n?=?12). Renal function and markers of oxidative stress and inflammation were evaluated. Also Nrf2-Keap1 and renal dopamine, antioxidant pathways were assessed. 5/6 Nx induced an altered renal autoregulation response, proteinuria, and hypertension; these effects were in association with increased oxidative stress, endothelial dysfunction and renal inflammation. The mechanisms associated with these alterations included a reduced nuclear translocation of Nrf2 and hyperphosphorylation of dopamine D1 receptor with a concurrent overactivation of renal NADPH oxidase. Treatments with MMF and curcumin provided equivalent therapeutic efficacy as both prevented functional renal alterations as well as preserved antioxidant capacity and avoided renal inflammatory infiltration. Moreover, both treatments preserved Nrf2-Keap1 and renal dopamine antioxidant pathways. In summary, therapeutic strategies aimed to preserve renal antioxidant pathways can help to retard the progression of CKD.     

Study on organochlorine pesticide levels in chronic kidney disease patients: association with estimated glomerular filtration rate and oxidative stress

Nephrotoxicity of organochlorine pesticides (OCPs) has been established in experimental animal models. This study was designed to evaluate the relationship of the blood OCPs level with the estimated glomerular filtration rate (eGFR) and oxidative stress (OS) in chronic kidney disease (CKD) patients. Patients in different stages of CKD (n = 150) and age, sex matched healthy controls (n = 96) were recruited. The blood OCPs level were analyzed by gas chromatography, and plasma levels of several OS parameters such as malondialdehyde (MDA), protein carbonyl, advanced oxidation protein products (AOPP), and total thiols were quantified by standard spectrophotometric methods. We observed significantly higher levels of hexachlorocyclohexane (α, γ), endosulfan, aldrin, p,p'-dichlorodiphenyldichloroethylene (DDE), and total pesticides in CKD patients. Negative correlation was also observed for aldrin, p,p'-DDE and total pesticides (p < 0.05) with eGFR. Plasma levels of MDA and AOPP showed significant positive association with the total pesticides level, indicating augmentation of OS with increased accumulation of OCPs in CKD patients.     

Simvastatin treatment prevents oxidative damage to DNA in whole blood leukocytes of dyslipidemic type 2 diabetic patients

Type 2 diabetes (T2D) is associated with increased oxidative stress as indicated by elevated levels of lipid peroxidation and protein oxidation products. Since reactive oxygen species (ROS) can cause damage to biological macromolecules including DNA, this study investigated oxidative damage to DNA using the alkaline (pH > 13) comet assay in peripheral whole blood leukocytes sampled from 15 dyslipidemic T2D patients treated with simvastatin (20 mg/day), 15 dyslipidemic T2D patients not treated with simvastatin, 20 non‐dyslipidemic T2D patients, and 20 healthy individuals (controls). Our results showed a greater DNA migration in terms of damage index (DI) (p < 0.01) in the dyslipidemic T2D patients not treated with statin (DI = 67.70 ± 10.89) when compared to the dyslipidemic T2D patients under statin treatment (DI = 47.56 ± 7.02), non‐dyslipidemic T2D patients (DI = 52.25 ± 9.14), and controls (DI = 13.20 ± 6.40). Plasma malondialdehyde (MDA) and C‐reactive protein (CRP) levels were also increased and total antioxidant reactivity (TAR) and paraoxonase activity (PON1) decreased in non‐dyslipidemic T2D patients and dyslipidemic T2D non‐treated with simvastatin. We also found that DI was inversely correlated with TAR (r = ?0.61, p < 0.05) and PON1 (r = ?0.67, p < 0.01). In addition, there was a significant positive correlation between DI and CRP (r = 0.80, p < 0.01). Our results therefore indicate that simvastatin treatment plays a protective role on oxidative damage to DNA in dyslipidemic T2D patients probably reflecting a general decrease in oxidative stress in these patients. Copyright © 2010 John Wiley & Sons, Ltd.