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Biomedical subjects

A Isimer

Publications and source records attributed to A Isimer.

At least 19 recordsLinked to original sources
PubMed2000

Defective antioxidant defense system in patients with a human leptin gene mutation.

Antioxidant defense system prevents the organism from the detrimental effects of free radicals via scavenging or inhibiting their formation. Changes in the antioxidant defense mechanisms and alterations of several essential trace elements in both plasma and various tissues of ob/ob mice have been reported previously. Recent finding of the restoration of the defective antioxidant enzyme activity after leptin treatment in ob/ob mice suggests a putative role of leptin in modulation of antioxidant enzyme activity. Therefore, the aim of this study was to investigate whether antioxidant enzymes and trace elements could also be altered in patients with leptin gene mutation. Seven patients (five men and two women, two of them are homozygous and 5 are heterozygous) with leptin gene mutation and 31 healthy, sex- and age-matched and non-related to the patients (24 male and 9 female), control volunteers were enrolled in the study. Plasma and erythrocyte glutathione peroxidase (GSH-Px) and erythrocyte copper-zinc superoxide dismutase (CuZn-SOD) activities were measured spectrophotometrically. Plasma selenium (Se), manganese (Mn), zinc (Zn), copper (Cu), and iron (Fe) levels were measured by atomic absorption spectrophotometry. Mean Cu and Fe levels in patients were not significantly different than those in controls whereas mean Se, Zn and Mn levels were significantly lower in patients than those of controls (P=0.007, P=0.001, and P=0.001, respectively). Erythrocyte GSH-Px (39%), plasma GSH-Px (24%) and erythrocyte CuZn-SOD activities (32%) were significantly lower than those of the control group (P=0.001, P=0.002, P=0.001, respectively). In conclusion, our results demonstrate that the activity of antioxidant enzymes and plasma levels of Se, Zn and Mn levels were decreased in both homozygous and heterozygous subjects with leptin gene mutation. We suggest that both leptin and trace elements might be involved in the modulation of antioxidant defense system.

Adult↗
PubMed1999

Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter.

Although endemic goiter has been shown to have a high prevalence in Turkey, little is known about the concentration of urinary iodine, plasma selenium (Se), copper (Cu), and zinc (Zn) in these patients. We studied on 140 male patient with endemic goiter (mean age: 22.2 +/- 0.19 yr) and 140 healthy male subjects (mean age: 21.8 +/- 0.28 yr). Daily urinary iodine excretion was determined by the ionometric method. Plasma Se, Zn, and Cu were determined by using atomic absorption spectrometry. Daily urinary iodine excretion was found to be significantly lower in the patient group (38.7 +/- 2.26 microg/d) than that of controls (50.73 +/- 2.56 microg/day, p = 0.001). Plasma Zn concentrations were also found to be significantly lower in the patient group (1.04 +/- 0.03 microg/mL) than that of controls (1.16 +/- 0.02 microg/mL, p = 0.001). No significant difference was determined in Se and Cu concentrations between the patient and control groups. Our study shows that a moderate iodine deficiency exists in both patients with endemic goiter and control subjects, which indicates the important role of iodine deficiency in the etiopathogenesis of endemic goiter in Turkey. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. However, Se and Cu do not seem to have any role in the etiopathogenesis of endemic goiter in Turkey. A community-based iodine fortification program throughout the country may be proposed to take over the problem, which also can prevent the contributing effects of other element deficiencies that occur when iodine deficiency is the prevailing factor.

Adult↗
PubMed1999

Beneficial effect of thyrotropin-releasing hormone on neuropathy in diabetic rats.

Thyrotropin releasing hormone (TRH) is therapeutically effective in experimental and clinical spinal injury. The effects of TRH on diabetic neuropathy are not known. The aim of the present study was to investigate the electrophysiological effects of TRH in the streptozotocin diabetic rats. Three groups of rats were studied, non-diabetic control (n = 10), diabetic controls (n = 8), and TRH treated diabetic rats (n = 9). Administration of TRH or saline and electrophysiological measurements were performed 4 weeks after induction of diabetes. TRH was given intraperitoneally in a dose of 600 microg (3 ml). Nerve conduction velocity (NCV), measured in caudal nerve, and N1 latency of somatosensory evoked potentials (SEP) were measured 75 min after injection of TRH or serum saline. SEP latencies were 28.1 +/- 0.6, 29.4 +/- 0.8, 27.8 +/- 1.1 ms, in normal, diabetic and diabetic TRH-treated groups, and NCV values were 28.1 +/- 0.8, 23.8 +/- 0.4, and 27.9 +/- 0.7 m/s respectively. NCV was significantly reduced in the diabetic group compared to normals (P < 0.05). but then improved by TRH treatment (P < 0.05). Our findings suggest that TRH has an acute effect on peripheral neuropathy in experimental streptozotocin diabetes in the rat.

Animals↗
PubMed1999

Aluminum content of vaccines used in Turkey.

Aluminum salts have been used in the preparation of a number of vaccines, toxoids, and allergen injectants as an adjuvant for many years. Although aluminum allergy is rare, there are many reported cases caused by aluminum-precipitated vaccines or hyposensitization therapy. Therefore, determination of the aluminum content of these vaccines is necessary information regarding adverse reactions related to these vaccines. In the present study, the aluminum contents of several vaccines (n = 19) routinely used in Turkey were, determined by electrothermal atomic absorption spectrophotometry. We found that aluminum levels in the vaccines ranged from 0.0 to 1438 mg/L.

Aluminum↗
PubMed1999

Noradrenaline and nitrite-nitrate concentrations in the contralateral testes during ipsilateral spermatic cord torsion in the presence or absence of a testis and epididymis.

OBJECTIVE: To determine the changes occurring during ipsilateral spermatic cord torsion either in the presence or absence of the ipsilateral testis and epididymis, by evaluating noradrenaline and nitrite-nitrate concentrations in the contralateral testes. MATERIALS AND METHODS: Forty male albino rats were allocated randomly to one of four equal groups undergoing: group 1, a sham operation; group 2, ipsilateral spermatic cord torsion; group 3, epididymo-orchidectomy only; and group 4, spermatic cord torsion after epididymo-orchidectomy. The contralateral testes were harvested after 24 h and the noradrenaline and nitrite-nitrate contents determined. The levels in each group were compared using the Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: The noradrenaline content of testes from group 2 was significantly lower than in those of groups 1 and 3, but there were no significant differences in content between groups 1 and 3, 1 and 4, and 2 and 4. The content in group 4 was significantly less than that in group 3. There were no significant differences in nitrite-nitrate contents among any of the groups. CONCLUSION: Spermatic cord torsion for 24 h, either in the presence or absence of a testis and epididymis, significantly decreased the noradrenaline content in the contralateral testis. This finding supports the suggestion that the sympathetic system is activated by exposure to noradrenaline in the contralateral testis during ipsilateral spermatic cord torsion, with no dependency on the presence of a testis and epididymis. As the nitrite-nitrate concentrations were unaffected, nitric oxide seems to have no role in contralateral testicular deterioration.

Animals↗
PubMed1998

Optimization of mobile phase in the separation of beta-blockers by HPLC.

Beta-blockers are generally determined using high-performance liquid chromatography (HPLC). Previous HPLC separations of beta-blockers have often required a mobile phase containing three components; acetonitrile or methanol to control the retention; buffer to control the ionic strength and pH of the mobile phase; ion-pairing reagent to provide adequate retention of beta-blockers or organic amines as masking agent to reduce peak tailing. Due to the complexity of the mobile phases employed, development of these assays can be a laborious process. Additionally, alkyl sulphonates and organic amines dramatically reduces the life-time reduction of silica based C18 columns. The results of this study demonstrated that the addition of tested alkyl sulphonates and organic amines is not essential for an adequate separation of beta-blockers. In this study, we developed a simple HPLC method for the simultaneous separation of model beta-blockers, atenolol, practolol, metoprolol, oxprenolol and propranolol. Atenolol, practolol, metoprolol, oxprenolol and propranolol adequately separated with high peak symmetries using a mobile phase consisted of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (15:15:70, v/v/v). By altering only the fraction of methanol with respect to acetonitrile, method development becomes a more efficient separation. Furthermore, atenolol, practolol, metoprolol, oxprenolol and propranolol can be detected up to 0.25, 5, 10, 50 and 10 ng ml(-1). In this publication, we present the simultaneous separation of beta-blockers having a wide range of polarity. It is proposed that this new mobile phase, consisting only acetonitrile, methanol and phosphate buffer can be used for the analysis of the several beta-blockers presently in doping control analysis as well as others.

Acetonitriles↗
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↗
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↗
PubMed1994

Plasma endothelin-1 concentrations in patients with Behçet's disease.

Plasma Endothelin-1 (ET-1) concentrations were determined by radio immunoassay in 30 patients with Behçet's disease at various stages and 20 healthy subjects. Mean ET-1 plasma concentrations were significantly (p < 0.001) increased in patients with active Behçet's disease (35.99 +/- 5.06 fmol/ml, mean +/- standard error) compared to concentrations found in healthy volunteers (10.98 +/- 0.84 fmol/ml). No difference in plasma ET-1 level was observed between patients with inactive Behçet's disease (12.98 +/- 1.14 fmol/ml) and volunteers. Increased plasma levels of ET-1 in patients with Behçet's disease may be attributable to increased secretion or leakage of this mitogen from injured vascular endothelial cells. These results indicate that ET-1 may play an important pathogenetic role in the development or progression of vasculitis common to Behçet's disease. Plasma concentrations of ET-1 correlates with the activity of illness.

Adult↗
PubMed1993

Determination of debrisoquine and 4-hydroxydebrisoquine in urine by high-performance liquid chromatography with fluorescence detection after solid-phase extraction.

A simple, selective and sensitive method has been developed to determine debrisoquine and 4-hydroxydebrisoquine in human urine. Separation of the analytes was obtained using a mobile phase of 0.1 M sodium dihydrogen phosphate-acetonitrile (87:13, v/v) and a muBondapak C18 column. The column effluent was monitored with fluorescence detection at 210 nm (ex) and 290 nm (em). Rapid sample preparation was achieved by solid-phase extraction columns (Bond Elut CBA, 3 ml capacity) which provided excellent recovery values for both compounds. The cost per sample using this approach could be minimized by column regeneration and re-use. The within-day and the day-to-day reproducibilities were less than 7% for both components. The method was shown to be suitable for the study of the debrisoquine-sparteine type genetic polymorphism in man.

Acetonitriles↗
PubMed1993

The effects of selenium supplementation on antioxidative enzyme activities and plasma and erythrocyte selenium levels.

Plasma and erythrocyte selenium levels in rabbits supplemented with therapeutic doses of selenium were studied by Zeeman graphite furnace atomic absorption spectrometry using a new palladium-ascorbic acid chemical modifier in order to achieve a higher precision. An improved coupled test procedure was used to determine the glutathione peroxidase (GSH-Px) activities. Superoxide dismutase activities were measured employing a method for the clinical assay of the enzyme. The selenium levels and GSH-Px activities both in the plasma and erythrocytes were higher in the supplemented group when compared to the controls. The SOD activities were increased in the erythrocytes but remained unchanged in the plasma. Or the other hand, a higher copper/zinc ratio was found both in the plasma and erythrocytes of the supplemented group. These findings support the importance of the dietary selenium intake in terms of the principal role of selenium in the cellular antioxidative mechanisms and imply that measurements of plasma selenium levels may be a notable sensitive indicator of the short-term selenium status.

Animals↗
PubMed1992

Trace elements in hydatid disease.

The serum and cyst fluid levels of selenium, zinc and copper were investigated both in patients and sheep with hydatid cysts. Results were compared with those of healthy subjects in both species. The serum values of Se, Zn and Cu in healthy subjects were 60.24 +/- 1.96 micrograms/L, 0.59 +/- 0.07 mg/L, and 1.01 +/- 0.08 mg/L, respectively. The corresponding serum values of the three trace elements in patients with hydatidosis were 41.30 +/- 1.94 micrograms/L, 1.27 +/- 0.08 mg/L, and 0.89 +/- 0.09 mg/L. These results show a decrease in Se and Zn, and a rise in Cu in sera of patients with hydatid disease. Similar results were obtained in infested sheep as related to the healthy control animals. Our results on the three trace elements were found to correlate well with the incidence of cirrhosis, malignant and infectious diseases and arthritis. Se was not detectable in cyst fluid, while Cu and Zn levels were found significantly lower than serum levels. Cu and Zn levels in cyst fluid showed no difference in both species. Variations in serum Cu, Zn and Se levels were insignificant with regard to the genus of the host and the fertile capacity of the hydatid cyst.

Adult↗