Dragan M. Djuric

Statin intolerance - an attempt at a unified definition. Position paper from an International Lipid Expert Panel.

Statins are one of the most commonly prescribed drugs in clinical practice. They are usually well tolerated and effectively prevent cardiovascular events. Most adverse effects associated with statin therapy are muscle-related. The recent statement of the European Atherosclerosis Society (EAS) has focused on statin associated muscle symptoms (SAMS), and avoided the use of the term ‘statin intolerance’. Although muscle syndromes are the most common adverse effects observed after statin therapy, excluding other side effects might underestimate the number of patients with statin intolerance, which might be observed in 10–15% of patients. In clinical practice, statin intolerance limits effective treatment of patients at risk of, or with, cardiovascular disease. Knowledge of the most common adverse effects of statin therapy that might cause statin intolerance and the clear definition of this phenomenon is crucial to effectively treat patients with lipid disorders. Therefore, the aim of this position paper was to suggest a unified definition of statin intolerance, and to complement the recent EAS statement on SAMS, where the pathophysiology, diagnosis and the management were comprehensively presented.

Lipid lowering nutraceuticals in clinical practice: position paper from an International Lipid Expert Panel

Arrigo F.G. Cicero, University of Bologna Alessandro Colletti, University of Bologna Gani Bajraktari, University Clinical Centre of Kosovo Olivier Descamps, Centres Hospitaliers Jolimont Dragan M. Djuric, University of Belgrade Marat Ezhov, Russian Cardiology Research and Production Centre Zlatko Fras, University Medical Centre Ljubljana Niki Katsiki, Aristotle University of Thessaloniki Michel Langlois, AZ Sint-Jan Hospital Gustavs Latkovskis, University of Latvia

In vitro evaluation of neurotoxicity potential and oxidative stress responses of diazinon and its degradation products in rat brain synaptosomes.

Although primary toxic action of organophosphorous insecticides is associated with acetylcholinesterase inhibition, later studies suggest that oxidative stress may be responsible for induced organophosphates toxicity. These studies mostly include thio forms, while the effects of their metabolites/degradation products have been less investigated. Therefore, this paper studies the toxic effects of diazinon degradation products, diazoxon and 2-isopropyl-6-methyl-4-pyrimidinol, and compares them with the toxic potential of the parent compound. The toxicity induced by various concentrations of the investigated compounds was in vitro evaluated by the activities of acetylcholinesterase, ATPases, antioxidant defense enzymes and lactate dehydrogenase, and malondialdehyde level in rat brain synaptosomes. Diazinon inhibited acetylcholinesterase and Na(+)/K(+)-ATPase in dose-dependent manner, while the inhibition of ecto-ATPase activity was less than 15% at all investigated concentrations. It did not demonstrate noteworthy prooxidative properties causing increase (up to 10%) in antioxidant enzymes activity and malondialdehyde level, as a marker of lipid peroxidation. Diazinon oxidation product, diazoxon was found as the most toxic investigated compound. Beside the expected strong inhibitory effect on acetylcholinesterase, it induced dose-dependent and almost complete inhibition of Na(+)/K(+)-ATPase and ecto-ATPase at the highest investigated concentration (0.1mM). Increasing diazoxon concentrations activated catalase (up to 30%), superoxide dismutase (up to 50%), glutathione peroxidase (up to 30%), and significantly increased malondialdehyde level (up to 50%). The investigated hydrolysis product of diazinon, 2-isopropyl-6-methyl-4-pyrimidinol did not remarkably alter the activities of acetylcholinesterase, Na(+)/K(+)-ATPase, catalase, glutathione peroxidase and lipid peroxidation level (up to about 10%). Although this diazinon metabolite has been known as non toxic, it induced superoxide dismutase stimulation up to 30%. Finally, even high concentrations of both diazinon and its metabolites did noticeably affect lactate dehydrogenase activity as a marker of synaptosomal integrity. The changes in investigated biochemical parameters in rat brain synaptosomes could serve as indicators of toxicity due to the exposure to thio organophosphates and/or their break-down products.

Comparison of blood pro/antioxidant levels before and after acute exercise in athletes and non-athletes

The aims of our study were to assess the redox state of adolescent athletes and non-athletes both at rest and after acute exposure to physical load and to find relations between parameters of redox state and morphofunctional characteristics of subjects. 58 young handball players and 37 non-athletes were subjected to body composition analysis, measuring of maximal oxygen consumption and blood sampling immediately before and after a maximal progressive exercise test. At rest, athletes had significantly higher superoxide dismutase (SOD) and catalase (CAT) activity, higher levels of glutathione (GSH) and nitric oxide (NO) and lower levels of lipid peroxidation (TBARS) compared with non-athletes. A maximal exercise test induced statistically significant rise of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and NO levels in non-athletes, while TBARS levels decreased. Athletes experienced the fall in NO levels and the fall in CAT activity. After exercise, athletes had significantly lower levels of O2- compared with non-athletes. Two way repeated measures ANOVA showed that the response of O2-, NO and TBARS to the exercise test was dependent on the sports engagement (training experience) of subjects. Significant correlations between morphofunctional and redox parameters were found. These results suggest that physical fitness affects redox homeostasis.

Oxidative stress in liver and red blood cells in acute lindane toxicity in rats

The aim of our study was to determine the role and dynamics of oxidative and nitrosative stress, as well as superoxide dismutase (SOD) and catalase activity in the hepatocytes and erythrocytes in early phase of acute lindane intoxication. Male Wistar rats were divided into groups: control, dimethylsulfoxide and lindane-treated groups (L, 8 mg/kg, intraperitoneally). Animals were sacrificed 0.5 and 4 hours after treatment (L0.5 and L4 groups, respectively). Oxidative and nitrosative stress parameters and antioxidant enzymes were determined spectrophotometrically. Liver and plasma thiobarbituric acid reactive substances (TBARS) concentration were significantly increased 0.5 after lindane administration (p < .01), with subsequent additional rise within 4 hours (p < .01), while plasma nitrite + nitrate level was significantly higher only 4 hours after lindane treatment. Total liver SOD activity was significantly increased in L4 group in comparison with control group (p < .01). In conclusion, oxidative and nitrosative stress play an important role in early phase of acute lindane hepatotoxicity. Antioxidant capacity of hepatocytes is partly increased, due to an adaptive increase in SOD activity.

Exercise Decreases Susceptibility to Homocysteine Seizures: the Role of Oxidative Stress

The aim of the study was to examine the effects of chronic exercise training on seizures induced by homocysteine thiolactone (HCT) in adult rats. Rats were assigned to: sedentary control; exercise control; sedentary+HCT; exercise+HCT group. Animals in the exercise groups ran 30 min daily on a treadmill for 30 consecutive days (belt speed 20 m/min), while sedentary rats spent the same time on the treadmill (speed 0 m/min). On the 31st day, the HCT groups received HCT (8.0 mmol/kg), while the control groups received vehicle. Afterwards, convulsive behavior and EEG activity were registered. Lipid peroxidation, superoxide dismutase (SOD) and catalase (CAT) activity were ascertained in the rat hippocampus. No signs of seizures were registered in sedentary and exercise control rats. Seizure latency was increased, while number of seizure episodes and spike-and-wave discharges (SWD) in EEG were decreased in the exercise+HCT compared to the sedentary+HCT group. Seizure incidence, the severity thereof and duration of SWDs were not significantly different between these groups. Exercise partly prevented increase of lipid peroxidation and decrease of the SOD and CAT activity after HCT administration. These results indicate beneficial effects of exercise in model of HCT-induced seizures in rats, what could be, at least in part, a consequence of improved antioxidant enzymes activity.

Effects of DL-Homocysteine Thiolactone on Cardiac Contractility, Coronary Flow, and Oxidative Stress Markers in the Isolated Rat Heart: The Role of Different Gasotransmitters

Considering the adverse effects of DL-homocysteine thiolactone hydrochloride (DL-Hcy TLHC) on vascular function and the possible role of oxidative stress in these mechanisms, the aim of this study was to assess the influence of DL-Hcy TLHC alone and in combination with specific inhibitors of important gasotransmitters, such as L-NAME, DL-PAG, and PPR IX, on cardiac contractility, coronary flow, and oxidative stress markers in an isolated rat heart. The hearts were retrogradely perfused according to the Langendorff technique at a 70 cm H2O and administered 10 μM DL-Hcy TLHC alone or in combination with 30 μM L-NAME, 10 μM DL-PAG, or 10 μM PPR IX. The following parameters were measured: dp/dt max, dp/dt min, SLVP, DLVP, MBP, HR, and CF. Oxidative stress markers were measured spectrophotometrically in coronary effluent through TBARS, NO2, O2 −, and H2O2 concentrations. The administration of DL-Hcy TLHC alone decreased dp/dt max, SLVP, and CF but did not change any oxidative stress parameters. DL-Hcy TLHC with L-NAME decreased CF, O2 −, H2O2, and TBARS. The administration of DL-Hcy TLHC with DL-PAG significantly increased dp/dt max but decreased DLVP, CF, and TBARS. Administration of DL-Hcy TLHC with PPR IX caused a decrease in dp/dt max, SLVP, HR, CF, and TBARS.

Toxic Effects of Palladium Compounds on the Isolated Rat Heart

Taken into consideration limited data about effects of palladium on cardiovascular system, the aim of our study was to compare toxicity of inorganic and organic palladium compounds on the isolated rat heart. The hearts (total number n=30, 6 for each experimental group) excised from Wistar albino rats, male sex, age 8 weeks, and body mass 180-200 g, were retrogradely perfused according to the Langendorff technique at constant perfusion pressure (70 cm H2O). After the insertion of sensor in the left ventricle, the parameters of heart function: maximum rate of left ventricular pressure development (dP/dt max), systolic left ventricular pressure (SLVP), diastolic left ventricular pressure (DLVP), mean blood pressure (MBP) and heart rate (HR)), were continuously registered. The experiments were performed during control conditions, and in the presence of perfusion with incresing concentration of the following: (triethanolamine (TEA), triethanolamine acetate (TEAA), palladium(II)chloride (PdCl2), and trans-dichlorobis(triethanolamine-N)palladium(II) complex (trans-[PdCl2(TEA)2])) started every 30 minutes (30, 60, 90, 120 minute). dP/dt max was not affected significantly by either TEAA, TEA, PdCl2 or Pd complex. SLVP was, also, not affected significantly by either TEAA, TEA, PdCl2, or Pd complex. DLVP was significantly decreased by both TEAA and PdCl2, while TEA and Pd complex did not show significant effect. MBP was significantly decreased only by PdCl2, while TEAA, TEA and Pd complex did not show significant effect. HR was significantly decreased by all compounds- PdCl2, TEAA, TEA and Pd complex. In our study, inorganic palladium compound (PdCl2) induced clear depression of the isolated rat heart contractility, manifested as drop in diastolic and mean blood pressure , and as decrease of the heart rate. On the other hand, it seems that palladium, when bound in an organic compound (linked to TEA in Pd complex), does not contribute significantly to cardio-toxicity in our experimental conditions.

Effect of acute lindane and alcohol intoxication on serum concentration of enzymes and fatty acids in rats

This study examines possible synergistic effects of lindane and ethanol on inducing liver injury and serum fatty acid derangement in adult male Wistar rats. When administered together, ethanol and lindane-induced even more pronounced increase of alanine aminotransferase (165 +/- 10 U/L) and gamma-glutamyltranspeptidase activity (10.3 +/- 0.6 U/L) than after isolated administration of either substance. In addition, separate administration of lindane and ethanol was followed by a significant decrease of linoleic acid level in the serum (301 +/- 38 mg/L, 276 +/- 35 mg/L vs. 416 +/- 48 mg/L). However, when ethanol administration was followed by lindane injection, serum linoleic acid was at the similar level found in the control group (516 +/- 62 mg/L). Ethanol-treated rats that received lindane 30 min after ethanol administration have shown a marked increase of palmitic (421 +/- 27 mg/L) and linolic acid level (43 +/- 5 mg/L) in comparison with rats that have been treated only with ethanol (316+/-26 mg/L for palmitic and 32 +/- 2 mg/L for linolic acid) or lindane (295 +/- 26 mg/L for palmitic and 301 +/- 38 mg/L for linolic acid). Linolic acid level was significantly greater in comparison with control group (29 +/- 1 mg/L). In conclusion, this study found enough evidence to support the hypothesis that acute ethanol intoxication potentiates lindane-induced liver injury and enhances lipid derangement.

The effect of N-methyl-D-aspartate receptor antagonists on D,L-homocysteine thiolactone induced seizures in adult rats.

The aim of our study was to investigate the effects of ifenprodil and MK-801 on D,L-homocysteine thiolactone induced seizures in adult rats.Male Wistar rats were divided into following groups: 1. Saline-treated (C, n=10); 2. D,L-homocysteine thiolactone 8 mmol/kg, i.p. (H, n=7); 3. Ifenprodil 20 mg/kg i.p. (IF, n=8); 4. MK-801 0.5 mg/kg, i.p. (MK, n=8) and 5. Groups that received IF or MK 30 minutes prior to H (IFH, n=8 and MKH, n=8). Seizure behavior was assessed by incidence, latency, number and intensity of seizure episodes. Seizure severity was described by a descriptive scale with grades 0-4. Lethality in experimental group was recorded 90 min and 24 h upon D,L-homocysteine thiolactone administration.There were no behavioral signs of seizure activity in groups C, IF and MK.Pre-treatment with MK-801 (MKH) showed tendency to reduced incidence of convulsions, latency to the first seizure onset and the severity of seizure episodes, but statistical significance was not attained comparing to the H group. However, median number of seizure episodes was significantly decreased in MKH (p<0.05), comparing to the H group. On the other hand, ifenprodil (IFH) decreased the latency to the first seizure onset and increased the median number of seizure episodes (p<0.05). The majority of seizure episodes in IFH (72.1%, p<0.05) and MKH (73.1%, p<0.05) groups was grade 2 and significantly different comparing to the H (36.0%). Our findings suggest that MK-801 has a mild anticonvulsive effect on D,L-homocysteine thiolactone induced seizures in adult rats.