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Biomedical subjects

G Güner

Publications and source records attributed to G Güner.

At least 19 recordsLinked to original sources
PubMed2001

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

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 fructosamine 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.

Animals↗
PubMed2001

Biochemical analysis of total collagen content and collagen types I, III, IV, V and VI in gingiva of various periodontitis categories.

Collagen is one of the chief components of the extracellular matrix of gingival connective tissue, where five different types have been identified to date. The molecular mechanism of collagen loss in periodontitis still needs to be explored. In the present study total collagen content was investigated in gingival connective tissue of adult periodontitis (AP) as well as early onset periodontitis patients (EOP) and clinically healthy subjects. Furthermore, collagen type I, III, IV, V andVI content was evaluated in gingival biopsies obtained from periodontitis patients. There was a statistically significant difference between AP (25.1 +/- 8.1 microg/mg) and EOP (15.6 +/- 4.0microg/mg) groups with regard to the total collagen content (P < 0.05). In the clinically healthy control group the total collagen content was 20.7 +/- 4.6microg/mg. Moreover, the distribution of collagen types exhibited variations in pooled homogenates of each periodontitis group. The total collagen loss seemed to be greater in the EOP patients than in the AP patients. When the ratio of fibril forming collagens to nonfibrillar collagens was evaluated, it seems to be decreased in AP patients in comparison to EOP patients. The findings of the present study suggest that different collagen types present in various periodontitis categories may be related with diverse pathogenic mechanisms acting in these diseases.

Adolescent↗
PubMed1999

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.

Acid Phosphatase↗
PubMed1999

Alterations in superoxide dismutase, glutathione peroxidase and catalase activities in experimental cerebral ischemia-reperfusion.

Free radicals are thought to be the most important cause of the reperfusion injury subsequent to ischemia. The antioxidant status of the tissue affected by ischemia-reperfusion is of great importance for the primary endogenous defense against the free radical induced injury. This investigation was performed to evaluate the antioxidant enzyme capacity of the brain tissue in the ischemia-reperfusion period using an experimental global moderate (penumbral) ischemia model on rat brains. Experiments were performed on 45 male Sprague Dawley rats. Ischemia was induced by bilateral vertebral arteries cauterization and temporary bilateral carotid arteries occlusion and sustained for 10 minutes. At the end of ischemia (0 min reperfusion) and various reperfusion periods (20 min, 60 min, 240 min), rats were decapitated and brains were frozen in liquid nitrogen. Changes in the intracellular antioxidant enzyme (superoxide dismutase, glutathione peroxidase and catalase) activities were assessed in the rat brain tissues, by spectrophotometric methods. In all moderate ischemia-reperfusion groups, superoxide dismutase activities were found to have decreased significantly compared to the sham operated controls (P < 0.05). During ischemia superoxide dismutase activity was lowered to 31% of that of the control group. The decreases were more significant in reperfusion groups, particularly in 60 min reperfusion (40%). Relatively smaller but still significant diminution was observed in glutathione peroxidase activities (P < 0.05). The ratio of diminution was striking in 20 min and 60 min reperfusion groups with 26% of the sham operated rats. Conversely, moderate ischemia-reperfusion caused significant increase in catalase activities (P < 0.05). The increment was 63% of the preischemic level with 10 min of moderate ischemia. In conclusion, activities of the major antioxidant enzymes were changed significantly in moderate brain ischemia-reperfusion. These results suggest that the disturbance in oxidant-antioxidant balance might play a part in rendering the tissue more vulnerable to free radical induced injuries.

Animals↗
PubMed1998

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.

Animals↗
PubMed1998

Anterior sacroiliac fusion: a new video-assisted endoscopic technique.

We present a case of sacroiliac fusion performed for an intraarticular osteochondroma of the sacroiliac joint, which was the cause of severe pain and disability. Excision of the lesion and sacroiliac fusion were successfully performed by utilizing minimally invasive surgical techniques. Although the application of this technique requires a dedicated and highly experienced team, the encouraging result of our first case, with minimal morbidity and disability due to the operation, induces us to recommend this technique in sacroiliac fusion, especially when fusion is combined with additional procedures such as drainage, biopsy, or excision.

Adult↗
PubMed1997

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

OBJECTIVES: To examine the impact of diabetic state on the concentrations of lipoprotein(a) [Lp(a)] in patients with non-insulin-dependent diabetes mellitus (NIDDM) and the correlation between angiographic coronary artery disease (CAD) and serum Lp(a) concentrations in NIDDM. DESIGN: In this cross-sectional study of 26 patients with NIDDM and 19 nondiabetic sex- and age-matched patients who underwent coronary angiography. CAD was assessed visually using coronary artery score (CAS), and plasma Lp(a) was measured by an enzyme-linked immunosorbent assay. SETTING: The study was performed in an internal medicine clinic at a university hospital. SUBJECTS: Twenty-six age- and sex-matched patients with NIDDM and 19 control patients without diabetes. RESULTS: There was no significant difference between the Lp(a) concentrations of patients with NIDDM and nondiabetic subjects (P > 0.05). When patients with NIDDM were stratified by absence or presence of CAD, patients with CAD had higher levels of Lp(a) (P < 0.05). However, there was no significant correlation between the concentrations of Lp(a) and CAS (P > 0.05). CONCLUSIONS: Diabetic state does not have any impact on Lp(a) concentrations. Lp(a) excess seems to be atherogenic in patients with NIDDM as shown in nondiabetic patients in previous studies. Although diabetic patients with CAD have higher Lp(a) concentrations than the diabetic patients without CAD, Lp(a) levels were not correlated with CAS.

Coronary Angiography↗
PubMed1997

Nisoldipine Cardioplegia in the Isolated Rabbit Heart.

BACKGROUND: The metabolic and hemodynamic effects of nisoldipine supplementation in cardioplegia after ischemic injury were investigated in 13 isolated rabbit hearts. Group 1 consisted of 6 hearts, which received St. Thomas II cardioplegic solution. In group 2, nisoldipine was added to the cardioplegic solution at a concentration of 0.1 mg/kg in 7 hearts. METHODS: The explanted hearts were suspended from Langendorff apparatus and were perfused with Krebs-Henseleit solution. Left ventricular pressure, heart rate, malondialdehyde, glutathione peroxidase, glutathione reductase, reduced glutathione, oxidized glutathione, creatine kinase MB, (CK-MB), aspartate transaminase, and lactate dehydrogenase (LDH) were measured before and after 60 minutes of ischemia. Peak generated pressure after ischemia was significantly higher in group 2 versus group 1 while end-diastolic pressure was significantly lower in group 2 after ischemic arrest (P <.05). RESULTS: Malondialdehyde levels were lower in group 2 (P <.05). Glutathione peroxidase and glutathione reductase levels were significantly higher in group 2 (P <.05). The only enzymatic significant difference was observed between the preischemic and postischemic levels of aspartate transaminase in group 2 (P <.05). CONCLUSIONS: These findings show beneficial effects of nisoldipine cardioplegia, although its use as a cardioplegic additive is not yet possible. We believe, however, the effects of oral nisoldipine before cardiac surgery can be studied in a clinical setting.

Journal Article↗
PubMed1996

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.

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

Arthroscopically assisted tibial plateau fracture management: a modified method.

We present a new technique for arthroscopically assisted treatment of tibial plateau fracture. This is a modification of previously described reduction and grafting techniques. We performed a core graft under the depressed fragment and used it for reduction. With the aid of anterior cruciate ligament surgery techniques, we aimed to simplify the graft harvesting and reduction for better healing.

Arthroscopy↗
PubMed1995

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.

Biomarkers, Tumor↗