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Biomedical subjects

G Toker

Publications and source records attributed to G Toker.

14 recordsLinked to original sources
PubMed2003

Callus formation and cucurbitacin B accumulation in Ecballium elaterium callus cultures.

Ecballium elaterium fruit juice is used for the treatment of sinusitis in Turkish folk medicine. The aim of this study was to increase the yield of cucurbitacin B, an anti-inflammatory compound previously isolated in various organs of E. elaterium, through tissue culture techniques. Higher yields of cucurbitacin B (1.126%) were obtained from the first subculture calluses from stem nodes in the presence of benzyl adenine (BA; 1 mg/l) and naphtalene acetic acid (NAA; 0.1 mg/l) in comparison with the yields obtained from plant material (0.01%).

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Comparative evaluation of the flavonoid content in officinal Tiliae flos and Turkish lime species for quality assessment.

Lime flowers are used for various medicinal purposes in phytotherapy. Flavonoids, volatile oil and mucilage components are known as the active ingredients. In European Pharmacopoeia (EP), a simple thin-layer chromatographic (TLC) technique, which based on the analysis of the flavonoid composition was defined for the qualitative analysis of the drug. In this study, flavonoid composition in the flowers, bracts and leaves of the officinal species, Tilia platyphyllos were studied using a reversed-phase high performance liquid chromatographic (HPLC) technique, in order to develop a rapid, reliable and accurate method for quantitative analysis. The results were further compared with in those parts of two common species growing in Turkey, Tilia rubra and Tilia argentea. Results of the present study revealed that flavonoid composition of each lime species possesses a specific fingerprint HPLC chromatogram depending upon the parts used and evaluation of the data might be helpful in the quality assurance as well as determination of adulteration of the crude drug.

Chromatography, High Pressure Liquid↗
PubMed2000

The effect of selenium and/or vitamin E treatments on radiation-induced intestinal injury in rats.

Cytotoxic effects of ionizing radiation on gastrointestinal epithelium may be related to oxidative stress. In this study, we wanted to investigate the effects of selenium, vitamin E and selenium plus vitamin E pretreatments prior to whole abdominal irradiation on intestinal injury. Irradiation caused increased lipid peroxide and decreased GSH levels in the intestine. Intestinal superoxide dismutase and glutathione peroxidase activities were increased, but glutathione transferase activity decreased following irradiation. Selenium and/or vitamin E pretreatments ameliorated these disturbances in prooxidant-antioxidant balance. This amelioriation has been verified with histopathological findings. These results indicate that antioxidant pretreatments prior to irradiation may have some beneficial effects against irradiation-induced intestinal injury.

Animals↗
PubMed2000

Triterpenoid saponins from Bongardia chrysogonum.

Two new triterpenoid saponins, 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-alph a-L-arabinopyranosyl]-hederagenin (1) and 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-alph a-L-arabinopyranosyl]-hederagenin 28-O-[beta-L-glucopyranosyl-(1-->6)-beta-L-glucopyranosyl] ester (2), together with five known saponins, were isolated from an ethanolic extract of the tubers of Bongardia chrysogonum. The structures of 1 and 2 were determined on the basis of spectroscopic studies.

Chromatography, High Pressure Liquid↗
PubMed1998

Increased lipoperoxide levels and antioxidant system in colorectal cancer.

In this study, lipid peroxide and glutathione (GSH) levels, GSH peroxidase, GSH S-transferase, superoxide dismutase, gamma-glutamylcysteine synthetase and gamma-glutamyl transpeptidase activities were investigated in tumorous and nontumorous colorectal tissues obtained from ten patients diagnosed with colon and rectum cancer. Histopathological evaluations, including type, stage, necrosis and lymphocyte infiltration, were also performed for each patient. According to the results, lipid peroxide and GSH levels and the activities of GSH peroxidase, superoxide dismutase, gamma-glutamylcysteine synthetase were found to be increased, while GSH S-transferase and gamma-glutamyl transpeptidase activities remained unchanged in tumors compared to adjacent normal tissues of subjects with colorectal cancer. However, the considerable interindividual variations were found in these parameters. A definite interrelation between histopathological results with lipid peroxidation and antioxidant system was not observed.

Adult↗
PubMed1998

Nitric oxide and radiation enteritis.

OBJECTIVE: To investigate the changes in intestinal nitric oxide (NO) and myeloperoxidase (MPO) concentrations, the rate of endotoxaemia, and intestinal mucosal structure in rats after irradiation of the abdomen and to find out the effect of Nomega-nitroarginine methyl ester (L-NAME) inhibition NO synthesis. SETTING: Medical school, Turkey. DESIGN: Experimental study. MATERIAL: 46 Wistar-albino rats. INTERVENTIONS: In Group I (n = 12), rats underwent abdominal irradiation alone. In Group II (n = 12), they underwent abdominal irradiation and were given L-NAME orally for 3 days before and 3 days after irradiation. In Group III (n = 12), rats had abdominal irradiation and were given L-NAME orally for 3 days after irradiation. Group IV (n = 10) were controls and were untreated. The irradiation procedure consisted of a single shot of 1000 cGy to the abdomen and L-NAME was given 30 mg/kg/day orally in the drinking water. MAIN OUTCOME MEASURES: Intestinal mucosal MPO and nitrite, and plasma endotoxin concentrations. Changes in villous height and number were recorded. RESULTS: In groups II and III, MPO and NO2- concentrations decreased significantly compared with group I. Mucosal integrity was protected in both groups treated with L-NAME (groups II and III) in contrast to the group given irradiation without treatment (group I). CONCLUSION: These results suggest that the NO pathway contributes to the inflammatory response of radiation enteritis. Inhibition of NO synthesis may have a beneficial effect in the treatment of inflammation caused by irradiation.

Animals↗
PubMed1997

The effect of chronic stress on hepatic and gastric lipid peroxidation in long-term depletion of glutathione in rats.

The effect of chronic stress (immobilization and cold) on hepatic and gastric thiobarbituric acid reactive substances (TBARS) and vitamin C levels were investigated in rats having long-term depletion of glutathione (GSH) by applying buthionine sulfoximine (BSO). GSH and vitamin C levels decreased and TBARS levels increased in the liver and stomach of rats subjected to stress. Long-term BSO administration along with stress caused no additional changes in these parameters. These results may indicate that long-term glutathione depletion did not potentiate stress-induced hepatic and gastric lipid peroxidation.

Animals↗
PubMed1997

Endogenous and copper-induced lipid peroxidation and antioxidant activity of serum in hypercholesterolemic subjects.

Endogenous malondialdehyde and diene conjugate levels were increased in hypercholesterolemic subjects with serum cholesterol levels above 240 mg/dl as compared to normocholesterolemic subjects (below 20 mg/dl). A decrease in vitamin E/cholesterol and vitamin C/cholesterol ratios was observed in serum of hypercholesterolemic individuals. However, the susceptibility of serum to copper-induced lipid peroxidation and antioxidant activity were found unchanged. The present study indicates that hypercholesterolemic subjects have a high level of circulating lipid peroxides and that a higher tendency towards atherosclerosis in these subjects may be related to increased baseline levels of serum lipid peroxides.

Adult↗
PubMed1997

Peroxidation status of erythrocytes and apolipoprotein B containing lipoproteins in hypercholesterolemic subjects.

Erythrocyte diene conjugate levels and glutathione peroxidase and superoxide dismutase activities were found unchanged in hypercholesterolemic subjects with plasma cholesterol levels of 240 mg/dl as compared to normocholesterolemics (below 200 mg/dl). However, the susceptibility of VLDL + LDL, apolipoprotein B containing lipoproteins to copper-induced peroxidation and plasma endogenous malondialdehyde levels were increased in hypercholesterolemics. These results indicate that hypercholesterolemia is associated with increased susceptibility of VLDL + LDL to lipid peroxidation.

Apolipoproteins B↗
PubMed1997

Mitochondrial lipid peroxides and antioxidant enzymes in the liver following phorone-induced glutathione depletion.

The levels of lipid peroxidation product (malondialdehyde = MDA) and vitamin C and the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were determined in the liver and its mitochondrial fraction, in the rats 2 and 18 hr after the injection of phorone, a glutathione (GSH) depleting agent. GSH levels decreased in liver homogenate and its mitochondrial fraction after 2 hr of phorone treatment, but these values returned to normal levels at 18 hr. In GSH depleted conditions, hepatic vitamin C levels increased, GSH-Px and SOD activities remained unchanged in mitochondrial and post-mitochondrial fractions. These results indicate that GSH depletion per se does not influence lipid peroxidation and GSH-Px and SOD activities in the liver and the mitochondrial fraction.

Animals↗
PubMed1997

The effects of interferon-alpha on serum lipid peroxidation and total thiol content in patients with chronic active hepatitis-C.

Chronic hepatitis develops in at least half of the patients with acute hepatitis C. Although there is currently no effective therapy for chronic hepatitis C (CHC), it is reported that Interferon-alpha (IFN alpha) has some beneficial effects. It has been suggested that changes in the oxidant-antioxidant balance may take decisive role in the progression of liver damage in viral hepatitis and IFN alpha might be effective in the treatment of liver damage by improving the antioxidant system. In the present study, when the patients with chronic active hepatitis-C (CAH-C) were compared to controls, serum thiobarbituric acid reactive substance (TBARS) levels and glutathione peroxidase (GPx) activity as well as transaminase activities were increased, but total sulfhydryl (t-SH) contents were decreased Following IFN alpha treatment three times a week for a period of 6 months, it has been observed that elevated TBARS levels and GPx activity were decreased and reduced t-SH contents were increased significantly in patients with chronic active hepatitis-C (CAH-C). According to our results, these findings suggests that oxidative stress may play an important role in HCV induced liver injury and IFN alpha may be useful in treatment by reducing the oxidative stress.

Adult↗
PubMed1995

Peroxidation potential and antioxidant activity of serum in patients with diabetes mellitus and myocard infarction.

Endogen malondialdehyde (MDA), diene conjugate levels, the susceptibility to copper-induced lipid peroxidation and antioxidant activity of serum were determined in patients with atherosclerotic diseases such as diabetes mellitus and myocard infarction. Lipid peroxidation susceptibility and antioxidant activity did not change, however, an increase in endogen MDA and diene conjugate levels was observed in serum of these patients. These results indicate the presence of oxidative stress in diabetes mellitus and myocard infarction.

Aged↗
PubMedDate not supplied

Lipid peroxides, glutathione, gamma-glutamylcysteine synthetase and gamma-glutamyltranspeptidase activities in several tissues of rats following water-immersion stress.

The effects of water-immersion restraint (WIR) stress on lipid peroxide, glutathione (GSH), glutathione peroxidase (GSH-Px), gamma-glutamylcysteine synthetase (gamma-GCS) and gamma-glutamyltranspeptidase (gamma-GT) activities in several tissues of rats were investigated. Hepatic and intestinal lipid peroxide levels were increased significantly in the WIR stress group. In both tissues, GSH levels were significantly decreased and gamma-GCS activity was significantly increased. In addition, gamma-GT activities remained unchanged in both tissues following WIR stress. However, lipid peroxide and GSH levels did not change in the stomach and brain in the WIR stress group compared to the control group. These results suggest that lipid peroxidation, but not the depression of GSH synthesis and/or the increase of GSH breakdown may be a factor in hepatic and intestinal GSH reduction following WIR stress.

Animals↗