Nedret Kiliç

The importance of serum lipids in exudative diabetic macular edema in type 2 diabetic patients.

Abstract:  To evaluate the relationship between serum lipid levels and exudative diabetic maculopathy in patients with nonproliferative diabetic retinopathy, 27 patients with exudative diabetic macular edema were included in group A and 27 patients without exudative diabetic macular edema were included in group B. All 54 patients have nonproliferative diabetic retinopathy. Blood cholesterol, triglyceride, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, very low‐density lipoprotein (VLDL) cholesterol, hemoglobin A1c (HbA1c), and hemoglobin levels were measured in patients in group A and group B. The mean concentration of cholesterol in group A (224.30 ± 49.49 mg/dL), in group B (197.78 ± 41.49 mg/dL); triglyceride in group A (199.11 ± 90.51 mg/dL), in group B (160.78 ± 65.30 mg/dL); HDL in group A (43.48 ± 10.62 mmol/L), in group B (42.37 ± 10.92 mmol/L); LDL in group A (150.59 ± 43.96 mg/dL), in group B (124.37 ± 40.28 mg/dL); VLDL in group A (40.52 ± 16.54 mg/dL), in group B (37.89 ± 23.70 mg/dL); HbA1c in group A (9.62 ± 2.50), in group B (7.36 ± 1.62 g/dL); and hemoglobin in group A (13.46 ± 1.6 g/dL), in group B (13.90 ± 1.77 g/dL). Serum cholesterol (P= 0.38), LDL (P= 0.026), and HbA1c (P= 0.000) levels were different between the two groups. Triglyceride, HDL, VLDL, and hemoglobin levels were not different between the two groups. We must consider regulation of high blood sugar and elevated total serum cholesterol or LDL levels in patients with macular edema and high hard exudates.

Effects of Taurine in Cellular Responses to Oxidative Stress in Young and Middle‐Aged Rat Liver

Abstract:  Aging is related with an increased cellular level of lipid peroxides and reactive oxygen species (ROS). The useful effects of taurine as an antioxidant in biological systems have been attributed to its capability to stabilize biomembranes, to scavenge ROS, and to decrease the peroxidation of unsaturated membrane lipids. The aim of the present study was to investigate the effects of taurine on malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), thioredoxin reductase (TR), and endothelial nitric oxide synthase (eNOS) in young and middle‐aged rat liver. There was not a significant difference in liver MDA levels between the control groups of young and middle‐aged rats (P > 0.05). However, liver GSH levels, and GPx and TR activities between the control groups of young and middle‐aged rats were significantly different (P < 0.05). Liver MDA level was significantly lower in the taurine group of middle‐aged rats (P < 0.05). Liver GSH levels, and GPx and TR activities were significantly increased in the taurine group of middle‐aged rats when compared to the control group (P < 0.05). Liver MDA level was significantly lower in the taurine group of young rats than the ones in the control group (P < 0.05). Liver TR activity was significantly increased in the taurine group of young rats when compared to the control group (P < 0.05). Liver GPx activity was not statistically different between the taurine and the control groups in young rats (P > 0.05). Liver GSH levels were not different between the young taurine and the control groups (P > 0.05). Immunohistochemical studies exhibited no change in eNOS activity after taurine injection in young rats. However, in middle‐aged rats, taurine lowered the eNOS reactivity to the same level found in young rats. These results suggested that exogenous taurine might play a role in aging by means of its reducing effects on free radical levels in parallel to an increase in the antioxidant capacity.

Neuroprotective effects of gabapentin on spinal cord ischemia-reperfusion injury in rabbits.

OBJECT Extensive research has been focused on neuroprotection after spinal cord trauma to alleviate the effects of secondary injury. This study aims to investigate the neuroprotective effects of gabapentin in an experimental spinal cord ischemia reperfusion injury. METHODS Thirty-two adult male New Zealand white rabbits received spinal cord ischemic injury using the aortic occlusion model. Animals were divided into 4 groups (sham, control, low-dose, and high-dose treatment groups; 8 rabbits in each group). High (200 mg/kg) and low (30 mg/kg) doses of gabapentin were administered to the animals in the treatment groups after spinal cord ischemic injury. Neurological status of the animals, ultrastructural findings in injured tissue samples, and levels of tissue injury markers in these 2 groups were compared with findings in the animals that did not receive the ischemic procedure (sham-operated group) and those that received normal saline after administration of ischemia. RESULTS Regarding levels of tissue injury marker levels after ischemic injury, animals in the gabapentin-treated groups demonstrated better results than animals in the other groups. The ultrastructural findings and caspase-3 activity were similar. The treatment groups demonstrated better results than the other groups. CONCLUSIONS Gabapentin demonstrated significant neuroprotection after early phases of ischemic injury. Further studies with different experimental settings including neurological outcome are required to achieve conclusive results.

Neuroprotective effects of infliximab in experimental spinal cord ischemic injury

Reactive oxygen species (ROS) have been implicated in the pathogenesis of spinal cord injury after both ischemia-reperfusion (I/R) and trauma. This experimental study was designed to investigate the potential effects of infliximab, an anti-tumor necrosis factor-α agent, on I/R injury of the rabbit spinal cord. Eighteen New Zealand white rabbits were divided into three groups, each consisting of six rabbits: sham (no I/R), I/R, and infliximab (I/R + infliximab). Spinal cord ischemia was induced by applying an infrarenal aortic cross clamp for 30 minutes. At 48 hours after ischemia, animals were functionally evaluated using the Tarlov score. Changes in the spinal cord were observed by measuring tissue levels of malondialdehyde (MDA), glutathione (GSH), advanced oxidation protein products (AOPP), and superoxide dismutase (SOD) and by evaluating hematoxylin-eosin-stained sections. At 48 hours after ischemia, the Tarlov scores in the infliximab group were higher than those of the I/R group, MDA and AOPP levels in the I/R group were significantly higher than those in the sham and infliximab groups (p < 0.05), and SOD levels in the infliximab group were significantly higher than those in the I/R and sham groups (p < 0.05). The sham group had higher GSH levels than the infliximab group; however, the difference was not statistically significant (p > 0.05). Histological examination revealed that the infliximab group had significantly less vascular proliferation, edema, and neuron loss than the I/R group. These results indicate that infliximab may protect the spinal cord against injury in a rabbit I/R model.

The effect of time of day and exercise on platelet functions and platelet-neutrophil aggregates in healthy male subjects

Platelet activation state changes by exercise. The effect of exercise time on platelet activation state and formation of platelet–neutrophil aggregates are not known yet. In this study the effect of exercise and time of day were examined on platelet activity with platelet–neutrophil aggregates. Ten moderately active males aged 27± 1.63 (mean±S.D.) years completed sub-maximal (70% VO2max) exercise trials for 30 min. Blood pressure (BP) was recorded. Venous blood samples were obtained at rest, immediately post-exercise and after 30 min of recovery. Whole blood was analysed for haematocrit (Hct), haemoglobin (Hb), platelet count (PC), mean platelet count (MPV) and platelet aggregation (PA). Platelet–neutrophil aggregates and beta-thromboglobulin (β-TG) levels were assayed. Platelet count showed significant increase after morning exercise ((236± 32)×109 l−1 versus (202± 34)×109 l−1 baseline, p < 0.05). Exercise resulted in significantly lower MPV after the evening exercise (9.16± 0.5 fl versus 9.65± 0.36 fl, p < 0.05). Platelet aggregation by adenosine diphosphate (ADP) decreased after morning exercise and the recovery aggregation levels were significantly different at two different times of the day (68± 20% a.m. versus 80± 12% p.m., p < 0.05). It was also showed that platelet–neutrophil aggregates increased significantly from baseline after both exercises. Exercise-induced platelet–neutrophil aggregates were higher in the evening (10.7± 1.3% p.m. versus 6.4± 1.8% a.m., p < 0.0001). It is therefore concluded that besides platelet–platelet aggregation, exercise can cause platelet– neutrophil aggregates. In addition, time of day has an effect on platelet activation related events. Circadian variations of physiological parameters may have an effect on thrombus formation by platelet activation. (Mol Cell Biochem xxx: 119–124, 2005)

An Investigation into the Serum Thioredoxin, Superoxide Dismutase, Malondialdehyde, and Advanced Oxidation Protein Products in Patients with Breast Cancer

BackgroundReactive oxygen species (free radicals) play an important role in carcinogenesis. Extensive antioxidant defense mechanisms counteract free radicals in mammalian cells. Oxidative stress is a disturbance in the balance between the production of free radicals and antioxidant defenses. There is direct evidence that oxidative stress and lipid peroxidation (LPO) are linked to the etiology of breast cancer. The increasing global incidence of breast cancer emphasizes the need to understand the various mechanisms involved in breast tumorigenesis. The present study was undertaken to investigate the oxidative stress and antioxidant status in the blood samples of patients with breast cancer.MethodsThe present study was based on 23 women who were surgically treated at Gazi University, Faculty of Medicine, Department of General Surgery. The malondialdehyde (MDA) levels as an index of LPO along with the examination of superoxide dismutase (SOD) activities and advanced oxidation protein product (AOPP) and thioredoxin (Trx) levels were determined in the blood samples of 23 patients with breast cancer and 13 healthy controls.ResultsMDA, AOPP, and Trx levels and SOD activities were significantly higher in patients with breast cancer than the controls.ConclusionsThe results showed that oxidative stress may be related to breast cancer and especially some molecules, such as Trx and AOPP, may be useful biomarkers in breast cancer diagnosis and treatment. More detailed knowledge related to the pathophysiology of these molecules could provide valuable information on the origin and development of malignant tumors, such as breast cancer.

Antioxidant Enzymes and Diabetic Retinopathy

Abstract:  The aim of this study was to discuss the serum copper (Cu), zinc (Zn), nitric oxide (NO), glutathione (GSH), advanced oxidation protein products (AOPP) levels, and superoxide dismutase (SOD) activities with diabetic retinopathy severity. Twenty‐five patients with proliferative diabetic retinopathy (PDR group 1), 25 patients with nonproliferative diabetic retinopathy (NPDR group 2), and 25 nondiabetic controls (control group) were included in the study. Patients who had macrovascular complications of diabetes (coronary arterial disease, periferic vascular disease) were excluded. The major finding of our study was that we did not observe any differences between group 1 and 2, which we aimed to discuss the severity of diabetic retinopathy. As the levels of SOD and Zn were not different between the groups, statistically significant differences were observed for GSH, NO, and Cu levels when compared to control group. AOPP levels were statistically increased in group 1 compared to control group. It can be suggested that hyperglycemia in DM is associated with accelerated nonenzymatic glycation and oxidative stress.

The evaluation of the oxidative stress parameters in nondiabetic and diabetic senile cataract patients.

The aim of the present study was to evaluate the copper (Cu), zinc (Zn), malondialdehyde (MDA), glutathione (GSH), and advanced oxidation protein products (AOPP) levels and superoxide dismutase (SOD) activities in diabetic senile cataract. Ten patients with diabetic senile cataract and ten patients with nondiabetic senile cataract (control group) were included in this study. AOPP, MDA, and GSH levels and SOD activity were measured by a spectrophotometric method. Serum, lens Cu, and Zn levels were measured by an atomic absorption spectrophotometric method. Both the lens and serum Zn and Cu levels between the two groups were not significantly different (p > 0.05). GSH, AOPP, and MDA levels and the SOD activities in the diabetic senile cataract group were significantly increased as compared to the control group (p < 0.05). Oxidative stress is one of the major factors which may lead to the early cataract formation. Oxidative events are of great importance in diabetic complications and, particularly in the lens, may have a role in the pathogenesis of cataract associated with diabetes mellitus as exhibited in this study.

Pseudoexfoliation syndrome and trace elements

Abstract:  To investigate the role of zinc and copper in the development of pseudoexfoliation (PSX) syndrome, 34 cataract patients with PSX syndrome and 27 cataract patients without PSX syndrome were included in the study and groups were matched for age and gender. During the cataract surgery, lenses were obtained intraoperatively, frozen under liquid nitrogen, and kept at −70°C until processing. Zinc and copper concentrations were measured by atomic absorption spectrophotometric method after the homogenization (acid hydrolysis) of dried lenses. The mean concentration of zinc in the lens from patients with PSX (20.33 ± 8.76 μg/g tissue; range 11.04–42.94 μg/g tissue) was significantly lower than that measured in the lens of patients without PSX (28.88 ± 15.32 μg/g tissue; range 12.02–64.32 μg/g tissue) (P < 0.05). The mean concentration of copper in the lens from patients with PSX (29.51 ± 10.05 μg/g tissue; range 12.69–59.71 μg/g tissue) and in the lens of patients without PSX (39.72 ± 25.64 μg/g tissue; range 12.38–92.14 μg/g tissue) was not statistically different. The decreased content of zinc could increase oxidative stress. The results support the role of oxidative stress in the development of PSX in cataract patients.

Effect of the sulfonylurea glyburide on superoxide dismutase in streptozotocin-induced diabetic rat muscle

1. The effect of glyburide (glibenclamide) treatment on the muscle superoxide dismutase (SOD) activity of diabetic rats has been studied. 2. Four weeks of treatment with glyburide (5 mg/kg, orally) increased muscle SOD activity and decreased blood glucose levels. 3. The results of this study demonstrate that the sulfonylurea, glyburide, is capable of exerting direct insulin-like effects on muscle SOD activity in vivo.