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O Canbolat

Publications and source records attributed to O Canbolat.

At least 19 recordsLinked to original sources
PubMed2000

Activities of adenosine deaminase and 5'-nucleotidase in cancerous and noncancerous human colorectal tissues.

In order to characterize human colorectal cancer, much attention has been paid to enzyme studies. However, little is known about the correlation between the levels of key enzymes of purine nucleotide pathway and some clinical and biological indicators of tumor invasiveness and aggressiveness. Adenosine deaminase (ADA) and 5'-nucleotidase (5'-NT) were measured in cancerous and cancer-free adjacent large bowel tissues from 38 patients with colorectal carcinoma. We have analyzed the relationship between the enzyme levels and some clinical and pathological parameters. The enzymes' activities were markedly higher in primary tumors than in corresponding normal mucosae. The ADA level in tumor tissue was significantly correlated with lymph node metastasis, histologic type, tumor location, and patient's age, whereas the 5'-NT level showed a significant correlation with tumor grade and tumor location. ADA activity in tumor tissues was significantly higher in patients whose clinical course remained stable than in those with recurrent diseases. The purine metabolism and salvage pathway activity of purine nucleotides are accelerated in the cancerous human colorectal tissue. Although our findings suggest that these enzymes' activities are most likely related to the same histomorphological architecture of the tumor, the authors believe that long-term follow-up studies are needed to evaluate the prognostic value of purine enzymes for colorectal cancer.

5'-Nucleotidase↗
PubMed2000

Alpha-lipoic acid treatment ameliorates metabolic parameters, blood pressure, vascular reactivity and morphology of vessels already damaged by streptozotocin-diabetes.

The present study investigated the effects of alpha-lipoic acid treatment (50 mg/kg/day) on the metabolism and vascular condition already damaged by streptozotocin (STZ)-diabetes in rats. Carbohydrate and lipid metabolism, oxidative stress and antioxidant status were assessed in non-diabetic controls, 12-week untreated diabetic and 12-week treated diabetic (untreated for 6 weeks and then treated with alpha-lipoic acid for the last 6 weeks) rats. Blood pressures of rats were measured by tail-cuff method. Vascular reactivity was evaluated in isolated aortic rings. Morphology of aorta was examined by electron microscopy technique. Alpha-lipoic acid treatment effectively reversed body weight, blood glucose, plasma insulin, cholesterol, triglycerides and lipid peroxidation levels of diabetic animals. STZ-diabetes resulted in increased blood pressure, which was partially improved by alpha-lipoic acid treatment. Although the superoxide dismutase (SOD) activity in aortic homogenates was not changed by diabetes or antioxidant treatment, catalase or glutathione peroxidase (GPx) activity significantly increased in untreated diabetic rats. Alpha-lipoic acid treatment improved catalase activity in diabetic aorta. The contractile effect of phenylephrine markedly increased in diabetic rings, which was completely reversed by alpha-lipoic acid treatment. The maximum vasorelaxant response of pre-contracted aortic rings exposed to cumulatively increased concentrations of acetylcholine was unaffected by diabetes or antioxidant treatment. Sodium nitroprusside-induced endothelium-independent relaxations were similar in all experimental groups. Various alterations caused by STZ-diabetes in aorta structure were partially ameliorated by alpha-lipoic acid treatment. The potency of alpha-lipoic acid on the reversal of hypertension by affecting vascular reactivity and morphology as well as general metabolism of diabetic rats confirms the importance of hyperglycemia-induced oxidative stress in the development of diabetes-induced vascular complications and suggests a potential therapeutic approach.

Animals↗
PubMed1999

The comparison of adenosine deaminase activity values with polymerase chain reaction results in patients with tuberculosis.

Three methods in the diagnosis and treatment of tuberculosis have been compared in this study. Serum adenosine deaminase activities of patients with tuberculosis was compared with those of control groups with (+) and (-) PPD (purified protein derivative) results and were found to be higher than the controls. Within the controls the PPD (+) group displayed higher adenosine deaminase activities in comparison to the PPD (-) group. All patients had growth of B. Tuberculosis in the culture medium and all but one had positive polymerase chain reaction (PCR) results. Control patients were negative for culture and PCR. The sensitivity of ADA (adenosine deaminase) assay was 91.7% and specificity was 94.5%, whereas PCR had a sensitivity of 95.8% and a specificity of 100%. The ADA assay may be used in adjunction with other methods in the follow-up of tuberculosis with high sensitivity, specificity, and ease in applicability and specimen collection.

Adenosine Deaminase↗
PubMed1998

Effects of modulators of the production and degradation of hydrogen peroxide on erythropoietin synthesis.

Erythropoietin (Epo) synthesis is suppressed in normoxia and stimulated in hypoxia. To test the hypothesis that the cellular H2O2 level is important in the control of Epo synthesis, we have studied effects of modulators of H2O2 generation and degradation on Epo production in human hepatic cell cultures (hepatoma lines HepG2 and Hep3B). In addition, we measured the activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase) in cultures following hypoxia exposure or H2O2 treatment. The results show that the formation of immunoreactive Epo was stimulated in normoxic cultures by treatment with exogenous catalase thus mimicking the effect of hypoxia (24 h incubation periods). Epo production was also stimulated when scavengers of reactive O2 species (tetramethylthiourea, dihydrorhodamine) were added to the cells. On the other hand, stimulators of H2O2 generation (xanthine oxidase, glucose oxidase, NADH, NADPH) lowered Epo production in hypoxic cultures. Hypoxia exposure decreased superoxide dismutase activity and H2O2 treatment reduced catalase activity thus influencing the endogenous antioxidant defense system. These findings support the concept that reactive O2 species, primarily H2O2, act as messengers in the O2-dependent control of the hepatic production of Epo. Changes in the cellular activities of antioxidant enzymes appear to play only a minor role in this process.

Carcinoma, Hepatocellular↗
PubMed1997

Activities of superoxide dismutase and glutathione peroxidase enzymes in cancerous and non-cancerous human kidney tissues.

The activities of superoxide dismutases (total, cytoplasmic and mitochondrial) and glutathione peroxidase were measured in 10 cancerous and 10 non-cancerous adjacent human kidney tissues. Total (T-SOD) and cytoplasmic (Cu, Zn-SOD) superoxide dismutase and glutathione peroxidase (GSH-Px) activities were found lower in cancerous tissues compared with those of non-cancerous ones. However, no difference was found between the mitochondrial (Mn-SOD) superoxide dismutase activities of the tissues. Similarly, no differences were observed between the enzyme activity values of the tissues at stage I-II and III-IV renal cancer. In correlation analysis the positive relation found between Cu, Zn-SOD and GSH-Px enzymes in the non-cancerous tissues was found to be absent in the cancerous ones. The results suggest that enzymatic free radical defense mechanism is significantly reduced in the cancerous human kidney tissues due to depressed Cu, Zn-SOD and GSH-Px activities.

Aged↗
PubMed1997

Impaired antioxidant defence in guinea pig heart tissues treated with halothane.

PURPOSE: To investigate the effects of halothane and halothane plus vitamin E treatment on myocardial free radical metabolism in guinea pigs. METHODS: Four groups of seven animals were studied: control, halothane, halothane plus vitamin E and vitamin E groups. In the halothane group, halothane 1.5% in oxygen was given for 90 min over three days. In the halothane plus vitamin E group, 300 mg.kg-1.day-1 vitamin E im was started three days before the first halothane treatment and continued for three days. Following sacrifice, the hearts were assayed for superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and malondialdehyde (MDA) level was determined. Electron spin resonance (ESR) analysis and electron microscopy (EM) were also performed. RESULTS: In the halothane group, SOD activities and MDA concentrations were increased compared with control and GSH-Px and CAT activities were decreased. In the halothane plus vitamin E group, there were no differences in enzyme activity compared with halothane alone but the MDA level was decreased. In the vitamin E group, enzyme activities were increased compared with control. Mainly the CF3CHCl radical was identified by ESR analysis in heart tissues exposed to halothane and the concentration of this radical was reduced by vitamin E. Electron microscopy showed cytoplasmic vacuolisation and dilation in sarcoplasmic reticulum in the heart tissues exposed to halothane: both were prevented by vitamin E. CONCLUSION: Although halothane causes impairment in enzymatic antioxidant defence potential, due to lowered GSH-Px and CAT activity, and accelerates peroxidative reactions in the tissues affected, no subcellular damage occurred. Vitamin E may protect tissues against free radical attack by scavenging toxic free radicals formed in heart tissue during halothane anaesthesia.

Anesthetics, Inhalation↗
PubMed1997

The effects of gentamicin on the activities of glutathione peroxidase and superoxide dismutase enzymes and malondialdehyde levels in heart tissues of guinea pigs.

In this study, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) levels were measured in heart tissues from guinea pigs treated with gentamicin and gentamicin plus vitamin E combination. Mean values were compared with those of the controls treated with only physiological saline solution. The activities of SOD and GSH-Px were found to be lower and the MDA level higher in the hearts from gentamicin-treated animals compared with those of the controls. In the gentamicin plus vitamin E group, however, tissue SOD activity was found to be increased and MDA level decreased significantly relative to the gentamicin group. GSH-Px activity was lowest in this group. Results suggest that gentamicin suppresses SOD and GSH-Px activities in heart tissue, thereby making the tissue more vulnerable to oxidative stress and peroxidative attacks, an important indicator of which is increased MDA level in the heart tissues from gentamicin-treated guinea pigs. This effect might be deleterious when gentamicin is used after cardiac surgery since a potential risk of free radical injury exists in the heart tissue during and/or after cardiac surgery owing to ischaemia and reperfusion processes, and, possibly, in the management of the patients with certain types of heart disease. Our results showed that vitamin E given concomitantly with gentamicin could protect the heart tissue against free radical injury.

Animals↗
PubMed1997

Activity of the enzymes participating in purine metabolism of cancerous and noncancerous human kidney tissues.

In this study, activity of some of the key enzymes participating in purine metabolism was measured in cancerous and noncancerous human kidney tissues from 18 patients with renal cell carcinoma. Twelve cancerous tissues were at stage T1-T2 and 6 tissues were at stage T3-T4. Adenosine deaminase (ADA) and guanase (GUA) activity was increased and xanthine oxidase (XO) activity decreased in cancerous tissues compared to noncancerous ones. No difference was, however, found between 5'-Nucleotidase (5'-NT) activity of the tissues. There were also no statistically meaningful differences between the enzyme activities of the cancerous tissues at stage T1-2 and T3-4. Results suggest that the changes observed in the activity of the enzymes participating in purine metabolism result from accelerated DNA turnover in the cancerous tissues and cells, and these changes might provide selective advantage, possibly by causing acceleration of salvage pathway activity, to the cancer cells to grow and develop more rapidly.

5'-Nucleotidase↗
PubMed1996

Activities of total, cytoplasmic, and mitochondrial superoxide dismutase enzymes in sera and pleural fluids from patients with lung cancer.

In this study, total cytoplasmic (Cu,Zn-SOD) and mitochondrial (Mn-SOD) superoxide dismutase activities were measured in sera and pleural fluids from patients with squamous cell carcinoma of the lung. The results were compared with those of control subjects and those of patients with tuberculosis and chronic heart failure. Serum activities were found higher in all patient groups compared to control group. Highest values were however in tuberculosis group. In the correlation analysis, meaningful intra- and inter-correlations were established between enzyme activities in the samples. Results suggest that high serum and pleural fluid SOD activities are not specific biochemical parameters for carcinogenesis and, activities may also increase in some other degenerative diseases such as tuberculosis, chronic heart failure, etc. Therefore, we believe that it is not useful to use serum and pleural fluid SOD activities for diagnostic purposes in cancer. However, the activities of these enzymes in the biological samples might be used as nonspecific prognostic markers in assessing cellular and mitochondrial tissue destruction.

Adult↗
PubMed1996

Activities of adenosine deaminase, 5'-nucleotidase, guanase, and cytidine deaminase enzymes in cancerous and non-cancerous human breast tissues.

We measured activities of some DNA turnover enzymes in 9 breast tissues with stage II cancer, 6 breast tissues with stage IIIa cancer, and 9 non-cancerous adjacent breast tissues from the same patients with stage II cancer. We found higher Adenosine Deaminase (ADA) and 5'-Nucleotidase (5'NT) and lower Guanase (GUA) activities in the cancerous tissues compared with the non-cancerous ones. No meaningful differences were however found between Cytidine Deaminase (CD) activities. Regarding the correlation analysis, positive correlations were established between ADA and 5'NT activities of the cancerous tissues (r = 0.45 for the tissues with stage II and r = 0.60 for the tissues with stage IIIa cancer). No meaningful correlations were however found between other enzyme activities. Relating to activity ratios, no meaningful differences were found between ADA/5'NT values in the tissues. GUA/CD ratios were however lower and the other ratios higher in the cancerous tissues. Results indicated that ADA and 5'NT activities increased and GUA activity decreased in the cancerous breast tissues but CD activities did not change in the tissues affected. It has been suggested that increased ADA and 5'NT together with decreased GUA activities might be a physiologic attempt of the cancer cells to provide more substrates needed by cancer cells to accelerate the salvage pathway activity. Furthermore, high ADA activity might also play part in the detoxication process of high amounts of toxic adenosine and deoxyadenosine substrates produced from accelerated purine metabolism in the cancerous tissues.

5'-Nucleotidase↗
PubMed1996

Halothane hepatotoxicity and hepatic free radical metabolism in guinea pigs; the effects of vitamin E.

PURPOSE: The aim of this study was to investigate the relation between halothane hepatotoxicity and hepatic free radical metabolism and to establish a possible protective role of vitamin E against halothane hepatotoxicity. METHODS: Twenty-eight guinea pigs were used in the experiments. Halothane (1.5% v/v) in oxygen (100%) was given to the animals for 90 min over three days. Livers from animals were then taken and prepared for the assays. In the enzymatic study, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were measured. As a peroxidation index, the malondialdehyde (MDA) concentration was determined. Also, electron spin resonance (ESR) analysis and electron microscopy (EM) were performed. RESULTS: Superoxide dismutase (1168.3 +/- 78.2 U.mg-1) and glutathione peroxidase (14.9 +/- 6.2 mIU.mg-1) activities were decreased, but catalase activity (1260.0 +/- 250.6 IU.mg-1) and malondialdehyde concentration (11.5 +/- 1.8 ppb) were increased in liver tissues exposed to halothane compared with control values (1382.2 +/- 91.8 U.mg-1 for SOD, 27.8 +/- 5.2 mIU.mg-1 for GSH-Px, 840.2 +/- 252.4 IU.mg-1 for CAT and 10.0 +/- 1.0 ppb for MDA). Electron spin resonance analysis revealed a peak of CF3CHCl. radical in the exposed tissue. Electron microscopy indicated ultrastructural changes in the hepatic cells of both halothane groups with and without vitamin E treatment. CONCLUSION: Halothane causes impairment in the hepatic antioxidant defense system and accelerates peroxidation reactions. As a result, some ultrastructural changes in hepatic tissues occur due to halothane treatment. Although vitamin E prevents peroxidative damage, it does not ameliorate ultrastructural changes caused by halothane treatment. This shows that halothane toxicity results not only from impaired hepatic antioxidant defense system but also from other, unknown causes.

Anesthetics, Inhalation↗
PubMed1996

Impaired enzymatic antioxidant defense mechanism in cancerous human thyroid tissues.

The activities of total superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes were measured in cancerous and non-cancerous adjacent tissues from 15 patients with follicular thyroid cancer containing single nodule. SOD and GSH-Px activities were found lower but malondialdehyde levels higher in cancerous tissues compared with those of noncancerous ones. However, no difference was found between CAT activities of the tissues. Activity decrease of GSH-Px enzyme in cancerous tissue was greater than that of SOD enzyme. Results suggested that enzymatic free radical defense system was significantly impaired and lipid peroxidation increased in the cancerous human thyroid tissues.

Adolescent↗
PubMed1996

Reduced enzymatic antioxidant defense mechanism in kidney tissues from gentamicin-treated guinea pigs: effects of vitamins E and C.

In this study, the activities of major enzymes participating in free radical metabolism (xanthine oxidase, XO; Cu,Zn and Mn superoxide dismutases, SOD; glutathione peroxidase, GSH-Px; catalase, CAT) were measured in kidney tissues from guinea pigs treated with gentamicin alone (200 mg/kg/day), gentamicin plus vitamin C (600 mg/kg/day), gentamicin plus vitamin E (400 mg/kg/day), and gentamicin plus vitamins C and E together for 10 days, and from animals treated with physiological saline solution alone during this period. We found no significant differences between control and gentamicin groups with respect to XO and Cu,Zn-SOD activities. However, the activities of Mn-SOD, GSH-Px, and CAT were found to be significantly depressed in the gentamicin-treated group relative to controls. In the gentamicin plus vitamin C group, the renal tissue Mn-SOD activity was found to be higher as compared with control and gentamicin groups. In this group, XO, GSH-Px and CAT activities were also higher than in the gentamicin-treated group, but no statistically significant differences existed between the values of this group and controls. Similar results were also observed in the gentamicin plus vitamin E group for Mn-SOD, GSH-Px, CAT, and XO. In this group, the Cu,Zn-SOD activity was found to be decreased as compared with control and gentamicin groups. In the gentamicin plus vitamins C and E group, the Cu,Zn-SOD activity was found to be decreased, the XO activity to be unchanged, and Mn-SOD, GSH-Px, and CAT activities to be increased as compared with the gentamicin and control groups. The results suggest that the enzymatic antioxidant defense system was significantly disturbed because of the suppressed activities of Mn-SOD, GSH-Px, and CAT in the kidney tissues from animals treated with gentamicin. However, vitamins C and E given concurrently with gentamicin completely abrogated this enzymatic suppression.

Animals↗
PubMed1994

Adenosine deaminase, 5'-nucleotidase, guanase and cytidine deaminase activities in gastric tissues from patients with gastric cancer.

The activities of some of the enzymes participating in nucleotide metabolism were measured in cancerous and noncancerous gastric tissues from patients with gastric cancer. The enzyme activities measured were found to be higher in the cancerous tissues than in the non-cancerous tissues. Adenosine deaminase (ADA), 5'-nucleotidase (5'-NT), guanase (GUA) and cytidine deaminase (CD) activities in the cancerous tissues were 56.0 +/- 24.0, 45.0 +/- 20.0, 0.34 +/- 0.16 and 4.65 +/- 2.04, respectively. The activities in non-cancerous tissues were 13.2 +/- 6.0, 19.8 +/- 8.3, 0.12 +/- 0.06 and 1.65 +/- 0.8, respectively. Cancerous tissues consisted of 7 gastric tissues with Grade I-II and 8 tissues with Grade III-IV adeno cancer. Non-cancerous adjacent tissues were obtained from the same patients with Grade I-II cancer. There were no meaningful differences between enzyme activities of the gastric tissues with Grade I-II and Grade III-IV cancer. Enzyme activity ratios indicates that ADA activity increased by the highest amount relative to other enzyme activities in the cancerous tissues. In the correlation analysis, we found positive correlations between some of the enzyme activities in the cancerous tissues. Results suggest that increased activities of these enzymes might play a part in the accelerated nucleotide metabolism in the cancerous gastric tissues.

5'-Nucleotidase↗
PubMed1994

Magnesium contents of leukemic lymphocytes.

In this study, magnesium concentrations were measured in lymphocytes from patients with acute myeloblastic leukemia (AML), chronic megalositer leukemia (KML) and acute lymphoblastic leukemia (ALL) before and after chemotherapy management, and results were compared with those of control subjects. Magnesium concentrations were higher in the patient groups compared with control values. However, no meaningful differences were found among magnesium concentrations of the patient groups themselves. Similarly, no statistically meaningful differences were found between lymphocyte magnesium concentrations before and after chemotherapy management in the patient groups. In the inter-correlation analysis, we observed no correlations between pre- and post-magnesium concentrations in patients' lymphocytes. It has been suggested that magnesium concentrations of leukemic lymphocytes might increase due to the high ATP requirement of the leukemic cells since magnesium is known to play an important part as a cofactor in most of the energy-producing reactions.

Adolescent↗