Askin Isimer

Oxidative stress and nitric oxide related parameters in type II diabetes mellitus: effects of glycemic control

OBJECTIVES The aim of this study is to investigate the status of oxidative stress and nitric oxide related parameters in type II diabetes mellitus (DM) patients in which heart disease, atherosclerosis, retinopathy, and nephropathy commonly occur, and also to determine the effect of glycemic control on these parameters. DESIGN AND METHODS Erythrocyte copper zinc-superoxide dismutase (CuZn-SOD), erythrocyte and plasma selenium dependent glutathione peroxidase (Se-GPx), erythrocyte catalase (CAT) activities, erythrocyte and plasma thiobarbituric acid reactive substances (TBARS) levels; nitrite/nitrate (NO(2)(-)/NO(3)(-)), cyclic guanosine monophosphate (cGMP) and nitrotyrosine levels in plasma of type II DM patients were measured. RESULTS Erythrocyte CuZn-SOD activities in type II DM were significantly higher than those of the control subjects (p < 0.05). TBARS levels in type II DM were significantly higher than the control subjects (p < 0.001). Plasma NO(2)(-)/NO(3)(-) levels in type II DM patients both during poor glycemic control and after three months of oral antidiabetic treatment were significantly higher than those of the control subjects (p < 0.001). Plasma cGMP levels in type II DM patients during poor glycemic control were significantly lower than those of control subjects (p < 0.001). CONCLUSION These results indicate that oxidative status and nitric oxide metabolism are affected in type II DM patients. We found high CuZn-SOD activity in type II DM patients. This increased activity could not protect the patients against the reactive oxygen species (ROS), since lipid peroxidation (defined by erythrocyte and plasma TBARS levels) still occurs in DM patients. After the therapy with oral antidiabetic agents for three months, erythrocyte SE-GPx and CAT activities were found to be decreased below the control values. Our results suggested that the low cGMP levels in the study may be a good marker of endothelium dysfunction in DM.

Increased oxidative stress and hypozincemia in male obesity

OBJECTIVES Antioxidants protect an organism from the detrimental effects of free radicals via scavenging or inhibiting their formation. Alterations in the levels of antioxidants and several essential trace elements in the plasma and various tissues of ob/ob mice have been reported previously. The aim of this study was to investigate oxidative status and trace elements in obese individuals. DESIGN AND METHODS Seventy-six obese men (body mass index (BMI) > 30 kg/m(2)) and 24 healthy, age-matched male control volunteers were enrolled in the study. Fasting plasma insulin, glucose, triglyceride (TG), total cholesterol, VLDL, and HDL levels, erythrocyte glutathione peroxidase (GSH-Px) and copper zinc-superoxide dismutase (CuZn-SOD) activities, and erythrocyte thiobarbituric acid reactive substances (TBARS) levels were measured in both groups. Erythrocyte copper (Cu), zinc (Zn) and iron (Fe) levels were also measured. RESULTS We found that the mean Cu and Fe levels in obese individuals were not significantly different than those in the control group, whereas the mean Zn levels were significantly lower than those of the control group (p = 0.023). The mean erythrocyte CuZn-SOD and GSH-Px levels in obese individuals were significantly lower than those in controls (p = 0.001) whereas erythrocyte TBARS levels were significantly higher (p = 0.001) than those of the control group. CONCLUSION We conclude that male obesity is associated with defective antioxidant status and hypozincemia, which may have implications in the development of obesity related health problems.

Effects of agmatine on ethanol withdrawal syndrome in rats

Effects of agmatine, which is an endogenous polyamine metabolite formed by decarboxylation of L-arginine, have been investigated on the ethanol withdrawal syndrome in rats. Adult male Wistar rats were used in the study. Ethanol (7.2% v/v) was given to the rats by a liquid diet for 21 days. Agmatine (20, 40, 80 and 160 mg/kg) and saline were injected to rats intraperitoneally 30 min before ethanol withdrawal testing. After 30th min, 2nd and 6th h of ethanol withdrawal, rats were observed for 5 min, and withdrawal signs which included locomotor hyperactivity, agitation, stereotyped behavior, wet dog shakes and tremor were recorded or rated. A second series of injections was given at 6 h after the first one, and subjects were then tested for audiogenic seizures. Agmatine caused dose-dependent and significant inhibitory effects on stereotyped behaviors, wet dog shakes and tremors during the observation period. It did not cause any significant change in motor coordination of naive (not ethanol-dependent) rats. Our results suggest that agmatine attenuates withdrawal syndrome in ethanol-dependent rats; thus, this drug may be beneficial in the treatment of ethanol dependence.

Plasma Trace Element, Plasma Glutathione Peroxidase, and Superoxide Dismutase Levels in Epileptic Children Receiving Antiepileptic Drug Therapy

Summary: Some antiepileptic drugs (AEDs) may altertrace element metabolism and free radical scavenging enzyme activities in humans and experimental animals. We investigated the effect of longterm AED therapy on copper (Cu), zinc (Zn), manganese (Mn), selenium (Se), magnesium (Mg), glutathione peroxidase (GSH‐PX), and superoxide dismutase (SOD) in the plasma in children with epilepsy. During treatment with valproate (VPA) or carbamazepine (CBZ) monotherapy plasma Cu, Zn, Mn, Se, and Mg concentrations of patients were not statistically different from those of control subjects. The level of seoxidation may be causally involved in some forms of epilepsies, and the decreased free radical scavenging enzyme activity is believed to cause the increased risk of anidiosyncratic drug reaction encountered in the manage‐ment of epilepsy. Because GSH‐PX and SOD are themost important members of antioxidant defense mechanisms, we quantitated the activities of these enzymes inplasma of children with epilepsy receiving VPA or CBZ. Only plasma GSH‐PX activities in VPA group werehigher than those of the control group, and the differencewas statistically significant.

The interaction between IL-1β and morphine: possible mechanism of the deficiency of morphine-induced analgesia in diabetic mice

&NA; It is known that diabetic mice are less sensitive to the analgesic effect of morphine. Some factor(s) derived from mononuclear cells, e.g. interleukin‐1&bgr; (IL‐1&bgr;), may be responsible for the diminished analgesic effect of morphine in diabetic mice. Therefore, we examined direct effects of IL‐1&bgr;, intracerebroventricularly (i.c.v.), on morphine‐induced analgesia, subcutaneously (s.c.), in diabetic and control mice by using the tail‐flick test. Morphine at doses of 1, 2 and 5 mg/kg (s.c.) produced dose‐dependent analgesia in diabetic and control mice but diabetic mice were less sensitive to the analgesic effect of morphine when compared to the controls. IL‐1&bgr; at a dose of 0.1 ng/mouse produced analgesia in control mice but not in diabetics, whereas IL‐1&bgr; at a dose of 10 ng/mouse produced a hyperalgesic effect both in diabetic and control mice. IL‐1&bgr; at a dose of 1 ng/mouse has neither an analgesic nor a hyperalgesic effect in control and diabetic mice. Administration of a neutral (neither analgesic nor hyperalgesic) dose of IL‐1&bgr;, 1 ng/mouse (i.c.v.), just prior to administration of morphine (s.c.) abolished the analgesic effect of morphine at doses of 1, 2 and 5 mg/kg in control mice and the analgesic effect of morphine became similar to that in diabetics. The diminished analgesic effect of morphine in diabetes was attenuated further with IL‐1&bgr; at a dose of 1 ng/mouse (i.c.v.). These results suggest that the decreased analgesic effect of morphine in diabetes may be related to IL‐1&bgr;.

Optimization of mobile phase in the separation of β-blockers by HPLC

Abstract β-blockers are generally determined using high-performance liquid chromatography (HPLC). Previous HPLC separations of β-blockers have often required a mobile phase containing three components; acetonitrile or methanol to control the retention; buffer to control the ionic strength and pH of the mobile phase; ion-pairing reagent to provide adequate retention of β-blockers or organic amines as masking agent to reduce peak tailing. Due to the complexity of the mobile phases employed, development of these assays can be a laborious process. Additionally, alkyl sulphonates and organic amines dramatically reduces the life-time reduction of silica based C18 columns. The results of this study demonstrated that the addition of tested alkyl sulphonates and organic amines is not essential for an adequate separation of β-blockers. In this study, we developed a simple HPLC method for the simultaneous separation of model β-blockers, atenolol, practolol, metoprolol, oxprenolol and propranolol. Atenolol, practolol, metoprolol, oxprenolol and propranolol adequately separated with high peak symmetries using a mobile phase consisted of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (15:15:70, v/v/v). By altering only the fraction of methanol with respect to acetonitrile, method development becomes a more efficient separation. Furthermore, atenolol, practolol, metoprolol, oxprenolol and propranolol can be detected up to 0.25, 5, 10, 50 and 10 ng ml−1. In this publication, we present the simultaneous separation of β-blockers having a wide range of polarity. It is proposed that this new mobile phase, consisting only acetonitrile, methanol and phosphate buffer can be used for the analysis of the several β-blockers presently in doping control analysis as well as others.

Enhanced release of solid dispersions of etodolac in polyethylene glycol

This work examines the release of etodolac from various molecular weight fractions of polyethylene glycol (PEG) solid dispersions. Solid dispersions of etodolac were prepared in different molar ratios of drug/carrier by using solvent and melting methods. The release rate of etodolac from the resulting complexes was determined from dissolution studies by use of USP dissolution apparatus 2 (paddle method). The physical state and drug:PEG interaction of solid dispersions and physical mixtures were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and differential scanning calorimetry (DSC). The dissolution rate of etodolac is increased in all of the solid dispersion systems compared to that of the pure drug and physical mixtures. The solid dispersion compound prepared in the molar ratio of 1:5 by the solvent method was found to have the fastest dissolution profile. The physical properties did not change after 9 months storage in normal conditions.

Selenium and Behçet's disease.

Behçets disease is an inflammatory disorder of unknown etiology, characterized by recurrent oral and genital aphthous ulcers, ocular inflammation, and skin lesions of erythema nodusum and acneiformeruptions. Selenium (Se) affects all components of the immune system, i.e., the development and expression of nonspecific, humoral, and cell-mediated responses. In general, a deficiency in Se appears to result in immunosuppression, whereas supplementation with low doses of Se appears to result in augmentation and/or restoration of immunoglogic functions. In this study, the distribution of Se and IgG, IgM in serum were compared in samples from healthy adult control and Behçets disease patients. The serum Se levels were measured by AA-30-40 Varian Spectra, and immunoglobulins were measured by immunodiffusion technique. The mean (SD) serum Se level of 54.24 ± 8.06 ng/mL among Behçets disease subjects was significantly different (P<0.01) from that in the control subjects (90.01 ± 9.94 ng/mL). We also measured IgG and IgM as 10.01 ± 2.74 mg/mL and 1.26 ± 0.29 mg/mL, respectively for patients, and 15.08 ± 4.73 mg/mL and 1.58 ± 0.43 mg/mL for controls. The mean values of IgG and IgM for patients were significantly (P<0.05) different from the values of controls. It seems, therefore, that a deficiency in selenium impedes the humoral immune response.

Accumulation of aluminum in rat brain: Does it lead to behavioral and electrophysiological changes?

The present study was undertaken to examine possible aluminum (Al) accumulation in the brain of rats and to investigate whether subchronic exposure to the metal leads to behavioral and neurophysiological changes in both treated and control groups. Each of the groups consisted of 10 animals. Aluminum chloride (AlCl3) at a low (50 mg/kg/d) or high (200 mg/kg/d) dose was applied to male Wistar rats by gavage for 8 wk. Al-free water by gavage was given to the control group throughout the experiment. Behavioral effects were evaluated by open-field (OF) motor activity and by acoustic startle response (ASR). Electrophysiological examination was done by recording spontaneous activity and sensory-evoked potentials from the visual, somatosensory, as well as auditory cortex. The Al content of each whole brain was determined by electrothermal atomic absorption spectrophotometry. Subchronic Al exposure slightly caused some changes in the evoked potentials and electrocorticograms and in the OF and ASR performance, but these results were not statistically significant. The brain Al levels of the control and the low and high dose of Al-exposed groups were measured as 0.717±0.208 µg/g (wet weight), 0.963±0.491 µg/g (wet weight) and 1.816±1.157 µg/g (wet weight), respectively.

Combined effects of cadmium and nickel on testicular xenobiotic metabolizing enzymes in rats

When male rats were given a single dose of cadmium (Cd) (3.58 mg CdCl2·H2O/kg, ip) 72 hr prior to sacrifice, the testicular 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities toward the substrates 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), ethacrynic acid (EAA), 1,2-epoxy-3-(p-nitrophenoxy)-propane (EPNP), and cumene hydroperoxide (CHPx) decreased significantly as compared to controls. Cd also inhibited reduced glutathione (GSH) level while increasing the lipid peroxidation (LP) level significantly. When the animals were given a single dose of nickel (Ni) (59.5 mg NiCl2·6H2O/kg, ip) 16 hr prior to sacrifice, significant decreases were observed in EROD and GST activities toward CDNB, EAA, EPNP, and CHPx, and GSH level. No significant alterations were noted in DCNB GST activity and LP level by Ni. For the combined treatment, rats received the single dose of Ni 56 hr after the single dose of Cd and were killed 16 hr later. In these animals, lesser depressions were observed on EROD activity and LP level than those of Cd alone. The combination of metals significantly inhibited GST activities and GSH level but not to a greater degree than noted by Cd or Ni alone. Plasma testosterone levels of Cd-, Ni-, and combination-treated rats decreased significantly compared to controls. The strongest depression was achieved by Cd alone. Cd, both alone and in combination with Ni, increased the tissue Ni uptake significantly. Ni, however, did not produce such an effect on the tissue uptake of Cd in either case. Cd treatment caused interstitial edema and coagulation necrosis in seminiferous tubules and also caused fibrinoidal necrosis in vascular endothelium. Ni treatment did not produce any pathological testicular alterations compared to controls. Combined treatment produced fewer pathological alterations (i.e., only interstitial edema) than that of Cd treatment. These results reveal that the combination of Cd and Ni does not have a synergistic effect on testicular xenobiotic metabolizing enzymes, and in contrast, Ni has an ameliorating effect on pathological disturbances caused by Cd alone in the rat testis.