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Biomedical subjects

A Sayal

Publications and source records attributed to A Sayal.

At least 19 recordsLinked to original sources
PubMed2004

Effects of statins on oxidative stress.

Free oxygen radicals and insufficient antioxidant enzymes have been implicated in the pathogenesis of hypercholesterolemia (HC). Trace elements function as cofactors in antioxidant enzymes. Antioxidant system and trace elements were investigated in many different studies including HC, but these subjects have not been investigated as a whole in these patients. The aim of the present study was to investigate the antioxidative system and trace elements in hypercholesterolemic patients given fluvastatin therapy. We examined malondialdehyde (MDA), copper zinc-superoxide dismutase (CuZn-SOD), and glutathione peroxidase (GSH-Px) activities together with copper (Cu), iron (Fe), and zinc (Zn) levels in erythrocytes of 35 patients with HC and 27 healthy control subjects. It was found that in patients with HC, erythrocyte MDA was significantly higher than those of controls and erythrocyte CuZn-SOD and GSH-Px activities were significantly lower in patients with HC. Erythrocyte iron levels were significantly higher than those of controls, and erythrocyte copper and zinc levels were significantly lower in patients with HC. Plasma lipid levels and the oxidative state were analyzed in statin-treatment groups given fluvastatin therapy before and after a 3-mo treatment period. In conclusion, we found that fluvastatin has significant antioxidant properties and these effects might be very important in managing dyslipidemia by improving endothelial function.

Adult↗
PubMed2002

Trace elements and antioxidant enzymes in Behçet's disease.

Free oxygen radicals and insufficiency of antioxidant enzymes have been implicated in the pathogenesis of Behçet's disease (BD). Trace elements function as cofactors to antioxidant enzymes. The antioxidant system and trace elements were investigated in many different studies, including BD, but these subjects have not been investigated as a whole in these patients. The aim of the present study was to investigate the antioxidative system and trace elements in BD to contribute to the knowledge of pathogenesis and treatment of this disease. We examined glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities together with selenium (Se), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) levels in plasma and erythrocytes of 50 patients with BD and 30 healthy controls. It was found that in patients with BD, erythrocyte GSH-Px and SOD activities and erythrocyte Se, plasma Fe, Mn, and Zn levels were significantly lower than those of controls and that plasma Cu, erythrocyte Zn, and Mn levels were significantly higher in patients with BD. Insufficient antioxidant enzyme activities were observed in patients with BD. The mechanism(s) of this phenomenon is not clear. Therefore, supplementation with trace elements involved in the antioxidative processes may increase scavenger enzyme activities, and consequently, an improvement in clinical symptoms may be expected.

Adult↗
PubMed2002

Investigation of antioxidant enzymes in children with autistic disorder.

Impaired antioxidant mechanisms are unable to inactivate free radicals that may induce a number of pathophysiological processes and result in cell injury. Thus, any abnormality in antioxidant defence systems could affect neurodevelopmental processes and could have an important role in the etiology of autistic disorder. The plasma levels of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), and erythrocyte levels of GSH-Px were investigated in 45 autistic children and compared with 41 normal controls. Levels of erythrocyte SOD, erythrocyte and plasma GSH-Px were assayed spectrophotometrically. Activities of erythrocyte SOD, erythrocyte and plasma GSH-Px in autistic children were significantly lower than normals. These results indicate that autistic children have low levels of activity of blood antioxidant enzyme systems; if similar abnormalities are present in brain, free radical accumulation could damage brain tissue.

Antioxidants↗
PubMed2001

Oxidative stress and nitric oxide related parameters in type II diabetes mellitus: effects of glycemic control.

OBJECTIVES: The aim of this study is to investigate the status of oxidative stress and nitric oxide related parameters in type II diabetes mellitus (DM) patients in which heart disease, atherosclerosis, retinopathy, and nephropathy commonly occur, and also to determine the effect of glycemic control on these parameters. DESIGN AND METHODS: Erythrocyte copper zinc-superoxide dismutase (CuZn-SOD), erythrocyte and plasma selenium dependent glutathione peroxidase (Se-GPx), erythrocyte catalase (CAT) activities, erythrocyte and plasma thiobarbituric acid reactive substances (TBARS) levels; nitrite/nitrate (NO(2)(-)/NO(3)(-)), cyclic guanosine monophosphate (cGMP) and nitrotyrosine levels in plasma of type II DM patients were measured. RESULTS: Erythrocyte CuZn-SOD activities in type II DM were significantly higher than those of the control subjects (p < 0.05). TBARS levels in type II DM were significantly higher than the control subjects (p < 0.001). Plasma NO(2)(-)/NO(3)(-) levels in type II DM patients both during poor glycemic control and after three months of oral antidiabetic treatment were significantly higher than those of the control subjects (p < 0.001). Plasma cGMP levels in type II DM patients during poor glycemic control were significantly lower than those of control subjects (p < 0.001). CONCLUSION: These results indicate that oxidative status and nitric oxide metabolism are affected in type II DM patients. We found high CuZn-SOD activity in type II DM patients. This increased activity could not protect the patients against the reactive oxygen species (ROS), since lipid peroxidation (defined by erythrocyte and plasma TBARS levels) still occurs in DM patients. After the therapy with oral antidiabetic agents for three months, erythrocyte SE-GPx and CAT activities were found to be decreased below the control values. Our results suggested that the low cGMP levels in the study may be a good marker of endothelium dysfunction in DM.

Adult↗
PubMed2000

Lipid peroxidation and antioxidant system in the blood of patients with Hodgkin's disease.

OBJECTIVES: The purpose of this study was to measure the extent of lipid peroxidation and the status of antioxidants in patients with Hodgkin's disease. DESIGN AND METHODS: Glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities, and malondialdehyde (MDA), selenium, zinc and copper content have been measured in 20 patients with Hodgkin's disease and 30 age-matched controls. RESULTS: Significantly higher concentrations of MDA in plasma as well as in erythrocytes were found compared to the control group. In both plasma and erythrocytes, GPX activity, selenium and zinc levels were significantly lower in patients than in controls. However, SOD activity in erythrocytes and copper levels in both plasma and erythrocytes were significantly higher in patients. CONCLUSION: We conclude that the antioxidant system is impaired in Hodgkin's disease due to the abnormal metabolism of trace elements and antioxidant enzymes.

Adult↗
PubMed2000

Oxidative stress status in adults with nephrotic syndrome.

BACKGROUND: Excessive generation of reactive oxygen species is one of the incriminated mechanisms in the pathogenesis of progressive renal injury. The role of oxidant stress in acute and chronic glomerular diseases has been investigated through experimental and clinical studies. SUBJECTS, MATERIALS AND METHODS: In the present study, oxidative stress status in adult nephrotic patients was studied by determining plasma selenium levels, erythrocyte and plasma glutathione peroxidase (GSH-Px) activities, erythrocyte superoxide dismutase (Cu-Zn-SOD) activity, erythrocyte and plasma levels of malondialdehyde (MDA). RESULTS: Twenty adult nephrotic syndrome patients included into the study had lower activities of erythrocyte (17.17 +/- 2.29 U/gHb) and plasma (153.76 +/- 20.12 U/l) GSH-Px activities when compared the controls ( 27.05 +/- 7.30 U/gHb and 308.89 +/- 55.04 U/l for erythrocyte and plasma GSH-Px activities, respectively). They also had lower erythrocyte Cu-Zn-SOD activity (1896.30 +/-94.31 U/gHb) than that of the controls (2506.17 +/- 461.08 U/gHb). Erythrocyte (483.40 +/- 37.45 nmol/gHb in patients vs 210.35 +/- 55.55 nmol/gHb in controls) and plasma (4.84 +/- 0.65 nmol/ml in patients vs 2.03 +/- 0.41 nmol/ml in controls) levels of MDA were higher in patients. Plasma selenium levels of the patients (48.0 +/- 7.28 ng/ml) were lower than that of the controls (69.25 +/-5.80 ng/ml). CONCLUSION: In conclusion, these results obtained in adult nephrotic syndrome patients support the previous data indicating an abnormality in antioxidative system of nephrotic patients.

Adolescent↗
PubMed1999

Lipid peroxidation and antioxidant system in the blood of cancerous patients with metastasis.

Free-radical-mediated damages may play an important role during metastasis. To investigate their relevance in the metastatic process MDA levels, glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities, and selenium, zinc and copper contents were determined in plasma and erythrocytes from 20 cancerous patients with metastasis and 30 age-matched controls. Significantly higher concentrations of MDA in plasma as well as in erythrocytes were found comparing to the control group. In both plasma and erythrocytes, GPX activity and selenium and zinc levels were significantly lower in patients than in controls. However, SOD activity in erythrocytes and copper levels in both plasma and erythrocytes were significantly higher in patients. The impaired antioxidant system may favor accumulation of free radicals which may induce the process of metastasis. On the other hand, it is possible that the antioxidant system is impaired as a consequence of abnormality in the antioxidative metabolisms due to the cancer process.

Adult↗
PubMed1998

Pulmonary function of workers in the aluminum industry.

The effects of aluminum on the pulmonary function of aluminum workers were investigated in this study. Serum aluminum levels and spirometry were measured in 55 male workers and 30 male controls. The mean serum aluminum level of workers (72.7 +/- 9.9 ng/ml) was significantly high compared to that of controls, indicating aluminum toxicity. Spirometric parameters were significantly lower in workers than in controls and correlated negatively with both exposure time and serum aluminum levels. The impairment in pulmonary function may be due to exposure time and insufficient protection.

Adult↗
PubMed1998

Antioxidative metabolism in Down syndrome.

Down syndrome is the most common cause of mental retardation, affecting 1 in 700-800 liveborn infants. Although numerous biochemical abnormalities accompanying the syndrome have not yet been completely clarified, the antioxidant defense system enzymes have shown to be altered due to increased gene dosage on chromosome 21 and overproduction of superoxide dismutase (SOD-1 or Cu/Zn SOD). The purpose of this study was to investigate the activities of SOD-1 and glutathione peroxidase (GSH-Px) enzymes and the levels of their cofactors zinc (Zn), copper (Cu) and selenium (Se) in plasma of 20 Down syndrome patients. In comparison with age and sex-matched controls (n = 15), plasma GSH-Px, SOD, and Cu levels were significantly decreased in the patient group, but Zn and Se concentrations remained unchanged.

Adolescent↗
PubMed1998

Role of excitatory aminoacids in neonatal hypoglycemia.

BACKGROUND: In many neurological disorders, injury to neurons may be due in part to overstimulation of the receptors for the excitatory amino acids glutamate and aspartate. The same excitotoxic mechanism and high aspartate levels in experimental studies led to this study of the concentrations of glutamate and aspartate and zinc, copper, and magnesium levels in the cerebrospinal fluid (CSF) of hypoglycemic newborns. METHODS: Aspartate and glutamate were determined by high-performance liquid chromatography, and magnesium, zinc and copper by atomic absorption spectrophotometer. RESULTS: The CSF levels of aspartate (3.98 +/- 1.77 mumol/L) and glutamate (1.7 +/- 1.05 mumol/L) in 20 hypoglycemic newborns were significantly higher when compared with the values of aspartate (2.19 +/- 0.6 mumol/L) and glutamate (0.77 +/- 0.34 mumol/L) of 10 control newborns. In the hypoglycemic patients, the concentration of zinc (0.57 +/- 0.13 microgram/mL), but not copper (0.39 +/- 0.40 microgram/mL) was significantly lower when compared with the control values. There was no difference in the magnesium levels between the two groups. CONCLUSIONS: The higher levels of excitatory amino acids found in the CSF of hypoglycemic infants than in controls were consistent with previous animal studies, which may indicate the role of excitatory amino acids in the late biochemical effects of hypoglycemia in newborn brain metabolism.

Aspartic Acid↗
PubMed1997

The hydroxylation of omeprazole correlates with S-mephenytoin and proguanil metabolism.

OBJECTIVES: This pharmacogenetic study was aimed at studying the pattern of oxidation of omeprazole in a Turkish population and testing whether omeprazole metabolism cosegregates with the genetically determined metabolism of mephenytoin and proguanil in Turkish subjects. METHODS: The hydroxylation of omeprazole was measured in 116 unrelated healthy Turkish subjects after administration of a single oral dose of omeprazole (20 mg), using the ratio of omeprazole to 5-hydroxyomeprazole in plasma 3 h after dosing. To 31 subjects, who were phenotyped with omeprazole, mephenytoin (100 mg, p.o.) or proguanil (200 mg, p.o.) were administered at least 1 week apart. The S/R ratio of mephenytoin and the ratio of proguanil to cycloguanil were determined from an 8-h urine collection. RESULTS: Based on the distribution of the log (omeprazole/hydroxyomeprazole) values and using the antimode value of 0.8, the frequency of poor metabolizers of omeprazole was estimated to be 7.7% (95% confidence interval 3-18%) which was similar to that in the other Caucasian populations (P = 0.54, Fisher's exact test). Three poor metabolizers of omeprazole were also classified as poor metabolizers of both mephenytoin and proguanil and no misclassification occurred with three phenotyping methods. All three methods separated poor or extensive metabolizer phenotypes with complete concordance. The ratio of omeprazole to hydroxyomeprazole correlated with the S/R ratio of mephenytoin and the ratio of proguanil to cycloguanil. CONCLUSION: These results support the hypothesis that the oxidative metabolism of three different drugs may be catalyzed by the same cytochrome P450 enzyme.

Adult↗
PubMed1996

Proguanil metabolism in relation to S-mephenytoin oxidation in a Turkish population.

The oxidation of proguanil was studied in 89 unrelated healthy Turkish volunteers after administration of proguanil (single dose, 200 mg, orally). Based on the distribution of the ratio of proguanil to cycloguanil excreted in urine, and using an antimode value of 15, the prevalence of poor metabolizers in a Turkish population was estimated to be 5.6% (95% confidence interval 2.0%-17.3%) which was similar to that in the other Caucasian populations. The relationship between the oxidative capacities of CYP2C19 for the two substrates, proguanil and mephenytoin, was studied in 39 subjects (two poor and 37 extensive metabolizers of proguanil). The two poor metabolizers of proguanil were also identified as poor metabolizers of S-mephenytoin and no misclassification by the two phenotyping methods was observed. The correlation between the metabolic ratio of proguanil to cycloguanil and the S/R-mephenytoin ratio as assessed by Spearman's rank test, was statistically significant (rs = 0.50, P < 0.001).

Adult↗
PubMed1996

Serum and pleural fluid selenium, copper, zinc, and magnesium levels in malignant and nonmalignant pleural diseases.

In the present study, selenium (Se), copper (Cu), zinc (Zn), and magnesium (Mg) levels in serum and pleural fluid from patients with malignant and nonmalignant pleural diseases were measured and compared with serum concentrations in healthy subjects. Serum/pleural fluid ratios were also calculated for each element. The purpose of this study was to evaluate the diagnostic value of trace metals, especially Se, in neoplastic and nonneoplastic pleural diseases. Serum Cu and Mg levels were significantly higher in both malignant and nonmalignant groups of patients when compared with control subjects (p < 0.05). However, serum levels of these elements did not show a significant difference between malignant and nonmalignant cases (p > 0.05). The serum/pleural fluid ratio of Zn was significantly lower in patients with malignant effusions than in benign conditions (p = 0.05). Serum and pleural fluid Se, Cu, Zn and Mg levels were not significantly different between the two groups (p > 0.05). Thus, Se, Cu, Zn, and Mg seem to have no diagnostic value for distinguishing malignant from nonmalignant effusions.

Adult↗
PubMed1995

Plasma trace element, plasma glutathione peroxidase, and superoxide dismutase levels in epileptic children receiving antiepileptic drug therapy.

Some antiepileptic drugs (AEDs) may alter trace element metabolism and free radical scavenging enzyme activities in humans and experimental animals. We investigated the effect of long-term AED therapy on copper (Cu), zinc (Zn), manganese (Mn), selenium (Se), magnesium (Mg), glutathione peroxidase (GSH-PX), and superoxide dismutase (SOD) in the plasma in children with epilepsy. During treatment with valproate (VPA) or carbamazepine (CBZ) monotherapy plasma Cu, Zn, Mn, Se, and Mg concentrations of patients were not statistically different from those of control subjects. The level of serum VPA weakly correlated with the increase in plasma Zn level. Recent studies suggest that membrane lipid peroxidation may be causally involved in some forms of epilepsies, and the decreased free radical scavenging enzyme activity is believed to cause the increased risk of an idiosyncratic drug reaction encountered in the management of epilepsy. Because GSH-PX and SOD are the most important members of antioxidant defense mechanisms, we quantitated the activities of these enzymes in plasma of children with epilepsy receiving VPA or CBZ. Only plasma GSH-PX activities in VPA group were higher than those of the control group, and the difference was statistically significant.

Adolescent↗
PubMed1994

Trace element (Al, Se, Zn, Cu) levels in serum, urine and tissues of burn patients.

Trace elements are known to play many important roles in humans. It has also been shown that some of these elements are essential in wound healing. In this study, aluminium, copper, zinc and selenium levels were determined in serum, urine and tissue samples of burned patients and the relationships between wound healing and trace elements were evaluated. Trace element levels were determined using atomic absorption spectrophotometry. During 20 days' treatment, a significant rise in aluminium levels was determined in serum, urine and tissue samples of patients. After day 5 of treatment, copper levels increased significantly only in urine samples. Zinc levels decreased in serum and tissue samples. However, zinc gave high values in urine within the first week then returned to the initial value. There was a significant decrease in zinc in serum and tissue samples taken from burned patients during treatment. Urine selenium levels showed a significant rise within the first 15 days.

Adult↗
PubMed1994

Polymorphic debrisoquin metabolism in a Turkish population.

Debrisoquin hydroxylation polymorphism was studied in 326 unrelated healthy Turkish volunteers. Debrisoquin sulfate (10 mg) was administered to subjects, and debrisoquin and 4-hydroxydebrisoquin were determined in the 0- to 8-hour urine samples. Debrisoquin oxidation was polymorphic, with 11 subjects (3.37%; 95% confidence interval, 1.69% to 6.07%) phenotyped as poor metabolizers. The metabolic ratio between debrisoquin and 4-hydroxydebrisoquin in 8-hour urine samples ranged from 0.02 in extensive metabolizers to 263.8 in poor metabolizers. The proportion of poor metabolizers was found to be in the range observed in the other white populations studied.

Adolescent↗
PubMed1994

S-mephenytoin, sparteine and debrisoquine oxidation: genetic polymorphisms in a Turkish population.

A mephenytoin test was carried out in 106 unrelated healthy Turkish volunteers. Racemic mephenytoin was coadministered with either debrisoquine or sparteine. The S/R mephenytoin ratio ranged from < 0.1 to 0.73 in 105 subjects, accordingly phenotyped as extensive metabolisers. One subject had an S/R mephenytoin ratio of 1.02, showing that he was a poor metaboliser of mephenytoin (0.94%, confidence interval 0.25% and 13.65%). In 48 subjects, the metabolic ratios of debrisoquine and sparteine were correlated significantly (rs = 0.61, P < 0.001).

Adolescent↗