Zeki Ilker Kunak

Beneficial Effects of N-Acetylcysteine and Ebselen on Renal Ischemia/Reperfusion Injury

Abstract Introduction: It has been demonstrated that peroxynitrite accompanies acute renal ischemia and contributes to the pathophysiology of renal damage. Therefore, we aimed to investigate the roles of N-acetylcysteine (NAC), a well-known powerful antioxidant, and ebselen (E), a scavenger of peroxynitrite, on renal injury induced by renal ischemia/reperfusion injury (IRI) of rat kidney. Materials and methods: Forty male Sprague–Dawley rats were divided into five groups: sham, renal IRI, renal IRI+NAC, renal IRI+E, and renal IRI+NAC+E. IR injury was induced by 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood samples were obtained for histopathological and biochemical evaluations. Results: Renal IR resulted in increased malondialdehyde and nitrite/nitrate levels suggesting increased lipid peroxidation and peroxynitrite production and decreased superoxide dismutase and glutathione peroxidase activities. Both NAC and E alone significantly decreased malondialdehyde and nitrite/nitrate levels and increased superoxide dismutase and glutathione peroxidase activities. Additionally in the renal IRI+NAC+E group, all biochemical results were quite close to those of sham group. Histopathologically, the kidney injury in rats treated with combination of NAC and E was found significantly less than the other groups. Conclusions: Both NAC and E are able to ameliorate IRI of the kidney by decreasing oxidative and nitrosative stresses and increasing free radical scavenger properties. Additionally, combination of NAC and E prevents kidney damage more than when each drug is used alone, suggesting that scavenging peroxynitrite nearby antioxidant activity is important in preventing renal IRI.

Simultaneous determination of cyclosporine A, tacrolimus, sirolimus, and everolimus in whole-blood samples by LC-MS/MS.

Objectives. Cyclosporine A (CyA), tacrolimus (TRL), sirolimus (SIR), and everolimus (RAD) are immunosuppressive drugs frequently used in organ transplantation. Our aim was to confirm a robust sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of CyA, TRL, SIR, and RAD in whole-blood samples. Materials and Methods. We used an integrated online solid-phase extraction-LC-MS/MS system and atmospheric pressure ionization tandem mass spectrometry (API-MS/MS) in the multiple reaction monitoring (MRM) detection mode. CyA, TRL, SIR, and RAD were simultaneously analyzed in whole blood treated with precipitation reagent taken from transplant patients. Results. System performance parameters were suitable for using this method as a high-throughput technique in clinical practice. The high concentration of one analyte in the sample did not affect the concentration of other analytes. Total analytical time was 2.5 min, and retention times of all analytes were shorter than 2 minutes. Conclusion. This LC-MS/MS method can be preferable for therapeutic drug monitoring of these immunosuppressive drugs (CyA, TRL, SRL, and RAD) in whole blood. Sample preparation was too short and simple in this method, and it permits robust, rapid, sensitive, selective, and simultaneous determination of these drugs.

Epigenetic perturbations in the pathogenesis of mustard toxicity; hypothesis and preliminary results.

Epigenetic perturbations in the pathogenesis of mustard toxicity; hypothesis and preliminary results Among the most readily available chemical warfare agents, sulfur mustard (SM), also known as mustard gas, has been the most widely used chemical weapon. SM causes debilitating effects that can leave an exposed individual incapacitated for days to months; therefore delayed SM toxicity is of much greater importance than its ability to cause lethality. Although not fully understood, acute toxicity of SM is related to reactive oxygen and nitrogen species, oxidative stress, DNA damage, poly(ADP-ribose) polymerase (PARP) activation and energy depletion within the affected cell. Therefore several antioxidants and PARP inhibitors show beneficial effects against acute SM toxicity. The delayed toxicity of SM however, currently has no clear mechanistic explanation. One third of the 100,000 Iranian casualties are still suffering from the detrimental effects of SM in spite of the extensive treatment. We, therefore, made an attempt whether epigenetic aberrations may contribute to pathogenesis of mustard poisoning. Preliminary evidence reveals that mechlorethamine (a nitrogen mustard derivative) exposure may not only cause oxidative stress, DNA damage, but epigenetic perturbations as well. Epigenetic refers to the study of changes that influence the phenotype without causing alteration of the genotype. It involves changes in the properties of a cell that are inherited but do not involve a change in DNA sequence. It is now known that in addition to mutations, epimutations contribute to a variety of human diseases. Under light of preliminary results, the current hypothesis will focus on epigenetic regulations to clarify mustard toxicity and the use of drugs to correct possible epigenetic defects.

Protective effects of melatonin and S-methylisothiourea on mechlorethamine induced nephrotoxicity.

BACKGROUND In this study, we aimed to investigate the protective effects of melatonin (MEL) and S-methylisothiourea (SMT) on mechlorethamine (MEC) induced nephrotoxicity. MATERIALS AND METHODS A total of 36 male Sprague-Dawley rats were divided into four groups: control, MEC, MEC+MEL, and MEC+SMT. Three groups received single dose of MEC (3.5 mg/kg) via transdermal route. Control animals were given saline only via transdermal route. MEL (100 mg/kg) was administered intraperitoneally 30 min after the application of MEC, and after the same dose of MEL was given every 12 h for a total of six doses. SMT (50 mg/kg) was also given intraperitoneally 30 min after the application of MEC. RESULTS The tissue TNF-α, IL-1β, and NOx levels were found significantly different for all groups (P < 0.001). MEC application resulted in severe histopathological changes. Melatonin showed meaningful protection against kidney damage. But protection by SMT was weaker. TNF-α and IL-1β levels increased significantly with MEC application, and MEL and SMT ameliorated these increases in kidney tissue. MEC also elevated NOx levels in kidney tissue. CONCLUSIONS Both inflammation and oxidative stress may have an important role in the MEC induced nephrotoxicity. MEL and SMT may also have anti-inflammatory properties, as well as anti-oxidant properties.

Plasma total homocysteine concentrations in a Turkish population sample.

Objectives — The purpose of this study is to determine the reference of plasma total homocysteine levels from a Turkish population and to investigate the relationship of plasma total homocysteine levels with sex and age groups. Design and methods — Plasma total homocysteine levels were measured in 2257 Turkish individuals (1381 men and 876 women) aged 1-90 years. Plasma total homocysteine concentrations were determined using high performance liquid chromatography with fluorescence detector. Results — The mean plasma total homocysteine level was significantly higher in men (mean, 10.6 μmol/L) than in women (mean, 8.7 μmol/L), P < 0.001. The mean plasma total homocysteine levels for the 1-10, 11-20, 21-30, and 31-40, 41-50, 51-60, and 61-70, 71-80, 81-90 age groups, were 6.5, 9.6, 10.1, and 10.4, 10.5, 10.9, and 11.3, 12.7, 14.6 μmol/L in men and 7.1, 7.6, 7.5, and 7.8, 8.7, 9.4, and 10.3, 11.2, 13.3 μmol/L in women, respectively. Conclusions — These data indicate the significance of sex- and age-associated differences of plasma total homocysteine levels in Turkish subjects. Plasma total homocysteine levels were increasing with age and men were found to have higher levels than women, as is found in other populations.

Protective efficiacy of taurine against pulmonary edema progression: experimental study.

Re-expansion pulmonary edema (RPE) is an acute, rare and potentially lethal complication [1,2]. Its beginning is sudden and dramatic. The mechanism is not yet fully understood [1]. Some authors suggest that it may occur after rapid re-inflation of a collapsed lung [1]. It was reported by other authors that it may relate to surfactant depletion or may result from hypoxic capillary damage, leading to increased capillary permeability [1,3]. In RPE, unilateral lung injury is initiated by cytotoxic oxygen metabolites and temporally associated with an influx of polymorphonuclear neutrophils [1]. These toxic oxygen products are the results of re-oxygenation of a collapsed lung. Treatment of re-expansion pulmonary edema is basically preventive [4].

The protective effect of melatonin and S-methylisothiourea treatments in nitrogen mustard induced lung toxicity in rats

OBJECTIVES Mustard is highly toxic to the lung. Its toxic effects are associated with inflammatory cell accumulation and increased pro-inflammatory cytokines as well as reactive oxygen and nitrogen species. In this study, we aimed to investigate the efficiency of melatonin (MEL) and S-methylisothiourea (SMT) on mechlorethamine (MEC) induced lung toxicity. METHODS Thirty-six male rats were randomly divided into four groups: control, MEC, MEC+MEL, and MEC+SMT. Control group was given saline only via transdermal route. Other groups were exposured to a single dose of MEC (3.5 mg/kg) via transdermal route. MEL (100 mg/kg) was administered intraperitoneally 30 min after the application of MEC, and after the same dose of MEL was given every 12 h for a total of six doses. SMT (50 mg/kg) was also given intraperitoneally 30 min after the application of MEC. RESULTS MEC injection resulted in alveolar epithelial injury, hemorrhage, inflammation, edema and interalveolar septal thickening in the lung tissues. The tissue TNF-α, IL-1β, and nitrate/nitrite (NOx) levels were found significantly different for all groups (p<0.001). TNF-α and IL-1β levels increased significantly with MEC exposure, and MEL and SMT ameliorated these increases in lung tissues. MEC also elevated NOx levels in lung tissue. Melatonin showed meaningful protection against lung injury. But protection of SMT was weaker. CONCLUSION Inflammation plays an important role in the MEC induced lung toxicity as well as oxidative and nitrosative stress. Melatonin has also anti-inflammatory properties similar to SMT, as well as anti-oxidant properties. But melatonin treatment was found more efficient than SMT treatment.

Measurement of TS-131, a New Monopyridinium Oxime, by High Performance Liquid Chromatography in Rat Plasma Samples

Aim TS-131 is a monopyridinium aldoxime-type cholinesterase reactivator developed as a potential alternative to commercially available oximes. A sensitive, simple and reliable high performance liquid chromatography (HPLC) method with diode array detector was developed for the measurement of TS- 131 concentrations in rat plasma samples.