Gül Güner

Determination of glutathione, glutathione reductase, glutathione peroxidase and glutathione S-transferase levels in human lung cancer tissues

This study was performed to elucidate the lung glutathione-related defense potential in tumoral tissues. Reduced (GSH) and oxidized (GSSG) glutathione, glutathione reductase (GR), selenium-dependent (SeGPx) and total glutathione peroxidase (tGPx), and glutathione S-transferase (GST) activities in 38 tumoral lung tissues and 17 normal lung tissues were determined to obtain a comprehensive profile of the lung glutathione and glutathione-related enzymes in cancer. The enzyme levels in tumoral tissues (n = 38) were found to be significantly higher (P < 0.05) than those in normal tissues (n = 17). Reduced glutathione levels, and not oxidized glutathione levels, were found to be higher in normal tissues than those in tumoral tissues. We found no statistically significant difference between the adenocarcinoma and squamous cell carcinoma groups for any of the parameters studied.

Evaluation of some antioxidant enzymes in lung carcinoma tissue

This investigation was effected to determine the levels of the two antioxidant enzymes, superoxide dismutase (SOD) (EC 1.15.1.1) and catalase (CAT) (EC 1.11.1.6) in lung cancerous tissues and to compare with normal lung tissue in order to evaluate the antioxidant status in lung cancer. Fifteen lung carcinoma tissue samples and the normal counterparts from the same cases were homogenized and the cytosols obtained by ultracentrifugation (100,000 x g). SOD was assayed using a modification of the indirect nitroblue tetrazolium assay method, while CAT was measured by a spectrophotometric method. The data obtained are as follows: 1.42 +/- 0.24 U/mg protein (means +/- SEM) of SOD in lung cancer and 3.13 +/- 0.51 U/mg protein in normal lung tissue and 33.53 +/- 6.09 U/mg protein of CAT in lung cancer and 71.33 +/- 14.38 in normal lung tissue. The differences were found to be significant at the level of P < 0.01 for both enzymes. These low levels of the antioxidant enzymes in lung cancerous tissues can lead to elevated levels of reactive oxygen metabolites, resulting in damage to the key subcellular structures such as DNA, cell membranes, and other vital cellular components.

Cytoprotective Effect of Trimetazidine on 75 min Warm Renal Ischemia-Reperfusion Injury in Rats

In this experimental study, we evaluated the effect of trimetazidine (TMZ) on renal ischemia-reperfusion (IR) injury in Sprague-Dawley rats. Renal IR was achieved by a 75-min clamping of the left renal pedicle and subsequent 24 h reperfusion, after right nephrectomy was performed. The rats were randomly divided into three groups: group 1 (sham operated: no IR injury), group 2 (ischemic control: saline treatment), and group 3 (3 mg/kg TMZ before ischemia). After 24 h of reperfusion, blood samples and renal tissue samples were taken to measure the levels of creatinine, tissue malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) activity. Histopathological changes were evaluated. In addition, the 7-day survival rates in each group were evaluated. We found significant increases in the levels of creatinine and tissue MDA, severe acute tubular necrosis, and a significant decrease in the activity of the GSH-Px in group 2. There were significant decreases in the levels of creatinine and tissue MDA, mild acute tubular necrosis, and a significant increase in activity of the GSH-Px in group 3 when compared with the control group (p <0.05). Statistically significant differences (p <0.05) in survival were noted between the ischemic control and sham-operated and TMZ groups. We have concluded that TMZ is able to protect the kidney from warm IR injury.

Basal serum nitric oxide levels in patients with type 2 diabetes mellitus and different stages of retinopathy

PURPOSE To compare the basal serum levels of nitric oxide (NO) in patients with type 2 diabetes mellitus and different stages of diabetic retinopathy (DR) with the levels in nondiabetic control subjects. METHODS The 39 patients with type 2 diabetes included in this study were divided by stage of DR into 3 groups: group A, those without DR; group B, those with background/preproliferative DR; and group C, those with proliferative DR. Eleven nondiabetic subjects made up the control group (group D). The NO concentration was determined indirectly by measuring the serum level of nitrite (NO2-) plus nitrate (NO3-) (NOx = NO2- plus NO3-) using a spectrophotometric method based on the Griess reaction. RESULTS The patients with type 2 diabetes had significantly higher levels of serum NOx than the nondiabetic controls (p = 0.0001). In addition, the levels in the patients with proliferative DR were significantly higher (p = 0.002) than the levels in the patients with nonproliferative or no DR. CONCLUSION Our study demonstrated both elevated levels of serum NOx in diabetic patients as compared with nondiabetic controls and a relationship between NOx and DR severity. Hence, abnormal NO metabolism may have a role in the pathogenesis of DR.

Evaluation of lipid peroxidation, cathepsin L and acid phosphatase activities in experimental brain ischemia–reperfusion

This investigation was conducted in rat brain tissues to elucidate the free radical induced cellular and subcellular membrane injuries in two different depth of global ischemia. Global moderate (penumbral) ischemia was performed on rat brains by bilateral vertebral arteries cauterization and temporary occlusion of the bilateral carotid arteries. Global severe ischemia was produced by a neck tourniquet in addition to four vessel occlusion. Somatosensory evoked potentials (SSEPs) were used as a feed back parameter to monitor electrophysiologically the ischemia. At the end of ischemic insult (0 min reperfusion) or various reperfusion periods (20, 60 and 240 min), all rats were decapitated and brains were frozen in liquid nitrogen. The brain tissues were prepared for the determination of cathepsin L (CL) and acid phosphatase (AP) activities in the supernatant (cytosolic) fraction (SF) and the fraction enriched with lysosomes (FEL). Further the level of thiobarbituric acid reactive substances (TBARS) of lipid peroxidation was assessed by the spectrophotometric methods. Severe ischemia-reperfusion was accompanied by a significant increase in TBARS levels and the SF/FEL ratio for CL and AP activities compared to the sham operated group and the concurrent reperfusion groups of moderate ischemia (p<0.05). There were no significant differences between the sham operated and moderate ischemia-reperfusion groups for the same parameters. Our data clearly demonstrate that; in rat brain although severe ischemia-reperfusion causes lipid peroxidation in cellular membranes and redistribution of lysosomal enzymes from lysosomes to cytoplasm due to lysosomal membrane injury, there are no changes in lysosomal membrane stability in moderate ischemia-reperfusion.

Ferritin: a tumor marker expressed by renal cell carcinoma.

Renal cell carcinoma (RCC) has been shown to secrete several hormones and biologically active substances that influence the host metabolism or induce paraneoplastic syndromes. Observation of anemia in 20% of patients with RCC and the spontaneous recovery of anemia following nephrectomy drew attention to the body iron metabolism. Ferritin was previously proposed as a tumor marker for RCC. In order to determine whether RCC cells actually produce ferritin, we studied ferritin levels in serum from peripheral and renal veins as well as from the tumor tissue and the healthy parenchyma from radical nephrectomy specimens of 22 patients with RCC. Ferritin levels both in sera and cytosols were measured by an enzyme immunoassay method. The mean serum ferritin level from the renal vein was 419.9 +/- 72.4 ng/ml, and it was 157.3 +/- 18.3 ng/ml from the peripheral vein (p < 0.05). Renal vein ferritin correlated with stage and had a significant impact on prognosis (p < 0.05). The mean cytosolic ferritin level of the cancer tissue was 705.6 +/- 56.9 ng/mg cytosol protein, whereas in the normal parenchyma it was 95.9 +/- 10.1 ng/mg cytosol protein. This was also highly significant (p = 1.15 x 10(-13)), suggesting that RCC cells probably express ferritin. As currently there exists no reliable tumor marker for RCC, the value of ferritin as a marker should be investigated further before drawing any clinical conclusions.

Effects of oral L-arginine supplementation on blood pressure and asymmetric dimethylarginine in stress-induced preeclamptic rats

This study was carried out to elucidate the role of asymmetric dimethylarginine (ADMA) and nitric oxide (NO) in preeclampsia development, and to investigate the effect of L‐arginine supplementation in rats. Preeclampsia was induced in pregnant rats using a stress model. L‐arginine was administered orally and ADMA, urinary nitrate, and protein levels were measured on the 20th day of pregnancy. Compared with the group of rats that are normally pregnant, the levels of blood pressure (BP), protein excretion, and ADMA were significantly increased in preeclampsia which returned to normal levels following the supplementation of L‐arginine. Both group of rats had similar urine nitrate levels. Arginine–ADMA–NO pathway is affected in preeclampsia. L‐arginine supplementation decreased hypertension (HT), proteinuria, and ADMA levels indicating that taking L‐arginine may be beneficial in preeclampsia treatment. Copyright

Erythrocyte membrane and cytoskeletal protein glycation and oxidation in short-term diabetic rabbits

Abstract The objective of this study was to elucidate the glycation and oxidation processes in plasma and erythrocyte membrane proteins as well as the major erythrocyte cytoskeletal protein, spectrin, using a short-term experimental rabbit diabetes model. Diabetes was induced with a single-dose alloxan injection. Spectrin was purified from erythrocyte ghosts with selective solubilization followed by gel filtration chromatography techniques, and tested for purity using sodium dodecyl sulfate-poly-acrylamide gel electrophoresis. Glycation in plasma proteins was measured as fructosamin3 using the nitroblue tetrazolium method, and in erythrocyte membrane and purified spectrin, as ketoamine equivalents, by the hydrazine/phenylhydrazine method. Protein oxidation in plasma, erythrocyte membrane proteins, and purified spectrin was evaluated in terms of sulfhydryl oxidation, based on cis-dichlorodiammine platinum (II) binding. Carbonyl formation was also measured in plasma and membrane proteins. Sulfhydryl oxidation, carbonyl groups and glycated protein levels showed statistically significant differences between the diabetic and control groups for both the plasma and the erythrocyte membrane proteins. The cis-dichlorodiammine platinum (II) binding was significantly different in diabetic rabbit erythrocyte spectrin, while glycation was not significantly different for this protein. Our data clearly demonstrate that both protein glycation and oxidation are biochemical alterations occurring in diabetes, even of short duration.

The effects of alpha-lipoic acid on MMP-2 and MMP-9 activities in a rat renal ischemia and re-perfusion model

Abstract Matrix metalloproteinases (MMPs) are enzymes that are responsible for degradation of extracellular matrix (ECM); they are involved in the pathogenesis of ischemia-re-perfusion (I-R) injury. We investigated the possible preventive effect of alpha-lipoic acid (LA) in a renal I-R injury model in rats by assessing its reducing effect on the expression and activation of MMP-2 and MMP-9 induced by I-R. Rats were assigned to four groups: control, sham-operated, I-R (saline, i.p.) and I-R+ LA (100 mg/kg, i.p.). After a right nephrectomy, I-R was induced by clamping the left renal pedicle for 1 h, followed by 6 h re-perfusion. In the sham group, a right nephrectomy was performed and left renal pedicles were dissected without clamping and the entire left kidney was excised after 6 h. LA pretreatment was started 30 min prior to induction of ischemia. Injury to tubules was evaluated using light and electron microscopy. The expressions of MMP-2 and MMP-9 were determined by immunohistochemistry and their activities were analyzed by gelatin zymography. Serum creatinine was measured using a quantitative kit based on the Jaffe colorimetric technique. Malondialdehyde (MDA) and glutathione (GSH) were analyzed using high performance liquid chromatography. Tissue inhibitor of metalloproteinase (TIMP)-2 and TIMP-1 were assessed using enzyme-linked immunosorbent assay (ELISA). I-R caused tubular dilatation and brush border loss. LA decreased both renal dysfunction and abnormal levels of MDA and GSH during I-R. Moreover, LA decreased significantly both MMP-2 and MMP-9 expressions and activations during I-R. TIMP-1 and TIMP-2 levels were increased significantly by LA administration. LA modulated increased MMP-2 and MMP-9 activities and decreased TIMP-1 and TIMP-2 levels during renal I-R.

Correlation between serum lipoprotein (a) and angiographic coronary artery disease in non‐insulin‐dependent diabetes mellitus

Abstract. Comlekqi A, Biberoglu S, Kozan 0, Bahqeci 0, Ergene 0, Nazli C, Kinay 0, Guner G (Dokuz Eylul University, Medical School, Inciralti, Izmir, Turkey). Correlation between serum lipoprotein(a) and angio‐graphic coronary artery disease in non‐insulin‐dependent diabetes mellitus. J Intern Med 1997; 242:449‐54.