Zipora Matas

The hydroxyl radical scavengers dimethylsulfoxide and dimethylthiourea protect rats against thioacetamide-induced fulminant hepatic failure

BACKGROUND/AIMS Reactive oxygen species, proinflammatory cytokines, glutathione depletion and nitric oxide have all been implicated in the pathogenesis of fulminant hepatic failure. The aim of the present study was to examine the respective roles of these factors in the pathogenesis of thioacetamide-induced fulminant hepatic failure in rats. METHODS Fulminant hepatic failure was induced by 3 consecutive intraperitoneal injections of thioacetamide (400 mg/kg) at 24-h intervals. Rats were pretreated with one of the following agents: the free radical scavengers dimethylsulfoxide (4 g/kg every 6 h) or dimethylthiourea (200 mg/kg every 12 h), the glutathione donor, N-acetylcysteine (130 or 200 mg/kg every 6 h), or the anti-tumor necrosis factor-alpha agents pentoxifylline (100 and 200 mg/kg) and soluble tumor necrosis factor receptor (100 or 1000 microg/rat). The nitric oxide synthase inhibitor N-mono-methyl arginine ester (L-NAME, 0.1 mg/ml) was administered in the drinking water, starting 7 days prior to thioacetamide administration. RESULTS Serum levels of liver enzymes, blood ammonia and prothrombin time and the stage of hepatic encephalopathy were significantly improved in rats treated with dimethylsulfoxide or dimethylthiourea compared to the other treatment groups (p<0.001). Liver histology and the survival rate in these rats were not adversely affected by thioacetamide administration (p<0.001), while in all the other treatment groups those parameters were similar to control rats with fulminant hepatic failure. Furthermore, dimethylsulfoxide ameliorated liver damage and improved survival even when its administration was initiated 8 and 16 h after the first thioacetamide injection. The hepatic concentration of methanesulfinic acid, which is produced after direct interaction of dimethylsulfoxide with hydroxyl radicals, was increased five-fold in rats treated with thioacetamide+dimethylsulfoxide (p<0.001), suggesting a role for hydroxyl radical scavenging in the protection from fulminant hepatic failure in this model. In the group of thioacetamide-treated rats that were pretreated with L-NAME, liver enzymes, blood ammonia levels and the mortality rate were higher than in the control group, treated with thioacetamide only. CONCLUSIONS In thioacetamide-induced fulminant hepatic failure, the hydroxyl radical scavengers dimethylsulfoxide and dimethylthiourea prevent liver injury. Neither N-acetylcysteine nor antagonists of tumor necrosis factor-alpha are protective in this rat model. Inhibition of nitric oxide formation aggravates liver damage and reduces the survival of rats with thioacetamide-induced liver damage.

Melatonin inhibits nuclear factor kappa B activation and oxidative stress and protects against thioacetamide induced liver damage in rats

BACKGROUND/AIMS Free radical-mediated oxidative stress has been implicated in the pathogenesis of acute liver injury. The aim of our study was to investigate whether melatonin, a potent free radical scavenger could prevent fulminant hepatic failure in rats. METHODS Liver damage was induced by two consecutive injections of thioacetamide (TAA, 300 mg/kg/i.p.) at 24 h intervals. Treatment with melatonin (3 mg/kg/daily, i.p) was initiated 24 h prior to TAA. RESULTS Twenty-four h after the second TAA injection, serum liver enzymes and blood ammonia were lower in rats treated with TAA+melatonin compared to TAA (P<0.001). Liver histology was significantly improved and the mortality in the melatonin-treated rats was decreased (P<0.001). The increased nuclear binding of nuclear factor kappa B in the livers of the TAA-treated rats, was inhibited by melatonin. The hepatic levels of thiobarbituric acid reactive substances, protein carbonyls and inducible nitric oxide synthase were lower in the TAA+melatonin-treated group (P<0.01), indicating decreased oxidative stress and inflammation. CONCLUSIONS In a rat model of TAA-induced fulminant hepatic failure, melatonin improves survival and reduces liver damage and oxidative stress. The results suggest a causative role of oxidative stress in TAA-induced hepatic damage and suggest that melatonin may be utilized to reduce liver injury associated with oxidative stress.

Effects of Peroxisome Proliferator-Activated Receptor Ligands, Bezafibrate and Fenofibrate, on Adiponectin Level

Objective—Adiponectin is adipose-specific secretory protein and acts as anti-diabetic and anti-atherosclerotic molecule. We previously found peroxisome proliferators response element in adiponectin promoter region, suggesting that peroxisome proliferator-activated receptor (PPAR) ligands elevate adiponectin. Fibrates are known to be PPARα ligands and were shown to reduce risks of diabetes and cardiovascular disease. Effect of fibrates on adiponectin has not been clarified, whereas thiazolidinediones enhance adiponectin. Thus, we explored the possibility and mechanism that fibrates enhance adiponectin in humans, mice, and cells. Methods and Results—Significant increase of serum adiponectin was observed in bezafibrate-treated subjects compared with placebo group in patients enrolled in The Bezafibrate Infarction Prevention study. Higher baseline adiponectin levels were strongly associated with reduced risk of new diabetes. Fibrates, bezafibrate and fenofibrate, significantly elevated adiponectin levels in wild-type mice and 3T3-L1 adipocytes. Such an effect was not observed in PPARα-deficient mice and adipocytes. Fibrates activated adiponectin promoter but failed to enhance its activity when the point mutation occurred in peroxisome proliferators response element site and the endogenous PPARα was knocked down by PPARα-RNAi. Conclusions—Our results suggest that fibrates enhance adiponectin partly through adipose PPARα and measurement of adiponectin might be a useful tool for searching subjects at high risk for diabetes.

Expression of Opioid Receptors During Heart Ontogeny in Normotensive and Hypertensive Rats

BACKGROUND The opioidergic systems are involved in modulating nociceptive stimuli. In addition, the recent results suggest that endogenous and exogenous opioids could play a role in the modulation of blood pressure and cardiac functions. However, little is known regarding the expression and role of opioid-binding sites in the heart. The decreased sensitivity to noxious stimuli in hypertensive rats raises the possibility of different developmental pattern expression of opioid-binding sites in normotensive versus hypertensive rats. METHODS AND RESULTS Opioid receptor expression in hearts from hypertensive and normotensive rats was studied during heart development by binding assays. From P1 until P90, the development of the heart in the two rat strains was accompanied by a gradual increase in the density of kappa-opioid receptors. Hearts from hypertensive rats expressed significantly higher levels of kappa receptors compared with those of normotensive rats. At ages older than P7, mu-opioid receptors could not be detected in hearts of both strains, whereas delta-opioid-binding sites gradually increased until reaching adult levels. Seven-day-old cardiomyocyte cultures of both rat strains expressed similar densities of delta or kappa receptors to those observed in hearts from 7-day-old neonates. The mu-binding sites were not detected in cardiomyocytes cultures. Similar to the in vivo state, cultured myocytes from hypertensive rats had significantly higher levels of kappa-binding sites (1.5 fold) compared with those of normotensive rats. The kappa sites are pertussis toxin sensitive, and the state of coupling of the receptor to G protein is similar for the two rat strains. CONCLUSION The role of opioid-binding sites in the heart is not completely clear. Hypertensive rats are known to be less sensitive to noxious stimuli compared with normotensive rats. It is controversial whether the site if application of noxious stimuli plays an important role in the sensitivity to pain in hypertensive rats. We suggest that the opioidergic system could play a role in the modulation of blood pressure in addition to its known effect on nociception.

Prevention of hepatic cirrhosis in rats by hydroxyl radical scavengers

BACKGROUND/AIMS Reactive oxygen species and oxidative stress were implicated in hepatic stellate cell activation and liver fibrosis. The aim of the present study was to examine whether the administration of free radical scavengers in vivo would prevent experimentally-induced hepatic cirrhosis in rats. METHODS Cirrhosis was induced by administration of thioacetamide (TAA; 200 mg/kg, i.p.) twice/week, for 12 weeks. Rats were treated concurrently with either dimethylsulfoxide (DMSO; 4 g/kg, s.c. or p.o.) or dimethylthiourea (DMTU; 200 mg/kg i.p.) three times a week. RESULTS Liver fibrosis (histopathological score, spleen weight, and hepatic hydroxyproline) was abolished in rats treated with TAA and either DMSO or DMTU (P < 0.001). Accordingly, the hepatic expression of alpha smooth muscle actin, tissue inhibitor of metalloproteinase 2 and collagen alpha1 (I) gene were inhibited. The hepatic level of methane-sulfinic acid (produced by the interaction of DMSO with hydroxyl radicals) was increased in rats treated with TAA + DMSO (P = 0.0005) and decreased after pretreatment of these rats with DMTU (P = 0.008). However, the hepatic levels of malondialdehyde, lipid peroxides and protein carbonyls were not lower in the DMSO- and DMTU-treated groups. CONCLUSIONS The administration of free radical scavengers prevented the development of TAA-induced liver cirrhosis probably associated with decreased oxidative stress.

Pyrrolidine dithiocarbamate protects against thioacetamide-induced fulminant hepatic failure in rats

BACKGROUND/AIMS Reactive oxygen species and nuclear factor kappa B (NF-kappaB) activation have been implicated in the pathogenesis of cell injury in experimental models of liver damage. The aim of the present study was to examine whether pyrrolidine dithiocarbamate (PDTC), an anti oxidant and inhibitor of NF-kappaB activation, would prevent hepatic damage induced in a rat model of thioacetamide (TAA)-induced liver failure. METHODS Fulminant hepatic failure was induced in the control and treatment groups by two intraperitoneal injections of TAA (either 300 or 400 mg/kg) at 24-h intervals. In the treatment groups, rats were treated also with PDTC (60 mg/kg/24 h, i.p.), initiated 24 h prior to TAA. RESULTS Liver enzymes, blood ammonia, and hepatic levels of thiobarbituric acid reactive substances (P<0.001) and protein carbonyls (P<0.05) were significantly lower in rats treated with PDTC compared to TAA only. Liver histology and the survival rate in the PDTC-treated rats were also improved (P<0.01 compared to TAA only). NF-kappaB activation, 2 and 6 h after TAA administration, was inhibited by PDTC. CONCLUSIONS In a rat model of fulminant hepatic failure, the administration of PDTC attenuated liver damage and improved survival. This effect may be due to decreased oxidative stress and inhibition of NF-kappaB activation.

Effect of long-term treatment with antioxidants (vitamin C, vitamin E, coenzyme Q10 and selenium) on arterial compliance, humoral factors and inflammatory markers in patients with multiple cardiovascular risk factors.

BackgroundAntioxidant supplementations have the potential to alleviate the atherosclerotic damage caused by excessive production of reactive oxygen species (ROS). The present study evaluated the effects of prolonged antioxidant treatment on arterial elasticity, inflammatory and metabolic measures in patients with multiple cardiovascular risk factors.MethodsStudy participants were randomly assigned to two groups. Group 1 received oral supplementation with 2 capsules per day of Mid Life Guard, SupHerb, Israel. In each capsule vitamin C (500 mg) vitamin E (200 iu), co-enzyme Q10 (60 mg) and selenium (100 mcg), Group 2 received matching placebo(SupHerb) for 6 months. Patients were evaluated for lipid profile, HbA1C, insulin, C-peptide, hs-CRP, endothelin, aldosterone, plasma renin activity and Homeostasis model assessment-insulin resistance (HOMA-IR). Arterial elasticity was evaluated using pulse wave contour analysis (HDI CR 2000, Eagan, Minnesota).ResultsAntioxidant-treated patients exhibited significant increases in large arterial elasticity index (LAEI) as well as small arterial elasticity index (SAEI). A significant decline HbA1C and a significant increase in HDL-cholesterol were also observed. In the placebo group, significant changes in LAEI, SAEI or metabolic measures were not observed.ConclusionsAntioxidant supplementation significantly increased large and small artery elasticity in patients with multiple cardiovascular risk factors. This beneficial vascular effect was associated with an improvement in glucose and lipid metabolism as well as decrease in blood pressure.

efficacy and safety of prolonged-release melatonin in insomnia patients with diabetes: a randomized, double-blind, crossover study

Background: Diabetes is a major comorbidity in insomnia patients. The efficacy and safety of prolonged-release melatonin 2 mg in the treatment of glucose, lipid metabolism, and sleep was studied in 36 type 2 diabetic patients with insomnia (11 men, 25 women, age 46–77 years). Methods: In a randomized, double-blind, crossover study, the subjects were treated for 3 weeks (period 1) with prolonged-release melatonin or placebo, followed by a one-week washout period, and then crossed over for another 3 weeks (period 2) of treatment with the other preparation. All tablets were taken 2 hours before bedtime for a period of 3 weeks. In an extension period of 5 months, prolonged-release melatonin was given nightly to all patients in an open-label design. Sleep was objectively monitored in a subgroup of 22 patients using wrist actigraphy. Fasting glucose, fructosamine, insulin, C-peptide, triglycerides, total cholesterol, high-density and low-density lipoprotein cholesterol, and some antioxidants, as well as glycosylated hemoglobin (HbA1c) levels were measured at baseline and at the end of the study. All concomitant medications were continued throughout the study. Results: No significant changes in serum glucose, fructosamine, insulin, C-peptide, antioxidant levels or blood chemistry were observed after 3 weeks of prolonged-release melatonin treatment. Sleep efficiency, wake time after sleep onset, and number of awakenings improved significantly with prolonged-release melatonin as compared with placebo. Following 5 months of prolonged-release melatonin treatment, mean HbA1c (±standard deviation) was significantly lower than at baseline (9.13% ± 1.55% versus 8.47% ± 1.67%, respectively, P = 0.005). Conclusion: Short-term use of prolonged-release melatonin improves sleep maintenance in type 2 diabetic patients with insomnia without affecting glucose and lipid metabolism. Long-term prolonged-release melatonin administration has a beneficial effect on HbA1c, suggesting improved glycemic control.

C-Reactive Protein as a Predictor of Incident Ischemic Stroke Among Patients With Preexisting Cardiovascular Disease

Background and Purpose— C-reactive protein (CRP) has emerged as an important predictor of cardiovascular disease, but there are few prospective data on its association with risk of ischemic stroke in patients at high risk. Methods— We examined the association between CRP levels and subsequent risk of incident ischemic stroke among 2979 patients with stable coronary heart disease included in a controlled clinical trial (Bezafibrate Infarction Prevention) that assessed the efficacy of bezafibrate, a fibric acid derivative, versus placebo for secondary prevention. CRP was measured by a high-sensitivity assay in plasma samples collected before randomization and again at the second follow-up year of an overall mean follow-up of 6.2 years. Results— Risk of ischemic stroke per 1000 person-years increased from 4.1% for baseline CRP in the lowest tertile (<2.3 mg/L; n=982) to 5.9% for levels at the middle tertile (2.3 to 5.4 mg/L; n=1013) and 10.5% for CRP levels at the upper tertile (>5.4 mg/L; n=984; P<0.001). With adjustment for potential confounders, baseline CRP levels in the top versus bottom tertile were associated with a 2.16-fold increased hazard (95% CI, 1.32 to 3.53) for ischemic stroke, and CRP levels measured after 2 years were associated with a hazard ratio of 2.43 (95% CI, 1.30 to 4.57). The risk of an incident ischemic stroke did not differ between the bezafibrate group compared with the placebo group regardless of baseline CRP levels. Conclusions— These findings, based on a large prospective study, demonstrate the risk prediction for incident ischemic stroke conferred by CRP levels in patients at high risk.

Comparison of hemostatic factors and serum malondialdehyde as predictive factors for cardiovascular disease in hemodialysis patients

Hemodialysis (HD) patients have accelerated cardiovascular morbidity and mortality rates compared with the general population. Identifying the factors that predict major coronary events in this population can direct the focus on prevention. This cross-sectional study compares known and suspected cardiovascular risk factors in HD patients with and without prevalent cardiovascular disease (CVD). In 76 HD patients (prevalent CVD, 44 of 76 patients), serum lipid, lipoprotein, apolipoprotein (Apo), plasma fibrinogen, tissue plasminogen activator (TPA), plasminogen activator inhibitor (PAI-1), and factor VII levels were measured using standard kits. Serum malondialdehyde (MDA; a marker of oxidative stress) was measured using spectrophotometry. Predictor variables were compared using analysis of variance and chi-squared tests, as appropriate. CVD prevalence was modeled using multiple logistic regression analysis, and odds ratios (OR) were calculated. Serum lipid, lipoprotein, Apo, plasma TPA, PAI-1, and factor VII values did not differ significantly from laboratory norms or discriminate for prevalent CVD in HD patients. Plasma fibrinogen levels were significantly elevated in HD patients compared with laboratory norms (369.4 +/- 130.02 v 276.7 +/- 77.7 mg/dL; P < 0.0001) but were not significantly different in HD patients with and without prevalent CVD. Serum MDA levels, both before and after the midweek HD treatment, were significantly elevated in all HD patients compared with laboratory norms (pretreatment, 2.6 +/- 0.8 nmol/mL; posttreatment, 2.1 +/- 0.3 v 0.91 +/- 0.09 nmol/mL; P < 0.01) and were significantly elevated in HD patients with prevalent CVD versus those without (pretreatment, 2.8 +/- 0.6 v 2.4 +/- 0.4 nmol/mL; P < 0.01; posttreatment, 2.3 +/- 0.4 v 1.94 +/- 0.2 nmol/mL; P < 0.01). Only serum MDA levels, both before and after the midweek treatment, contributed to the explanation of variation in CVD prevalence. OR for CVD in the highest versus lowest tertile of pretreatment MDA level was 2.71 (95% confidence interval [CI], 1.42 to 5.19). ORs for CVD in the highest versus lowest tertile of posttreatment MDA level was 3.65 (95% CI, 1.6 to 8.32).