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Biomedical subjects

G Koçak

Publications and source records attributed to G Koçak.

15 recordsLinked to original sources
PubMed2002

Elimination of *O(2)(-)/H(2)O(2) by alpha-lipoic acid mediates the recovery of basal EDRF/NO availability and the reversal of superoxide dismutase-induced relaxation in diabetic rat aorta.

AIM: The aims of this study were to ascertain the mechanism(s) of relaxant action of exogenous superoxide dismutase (SOD) in aortic rings obtained from 12-week, streptozotocin(STZ)-diabetic and age-matched control rats, and to examine the effects of alpha-lipoic acid (ALA) treatment (for 6 weeks, after 6 weeks of untreated diabetes) on SOD-induced relaxations. MATERIALS AND METHODS: Thoracic aorta rings were suspended to isolated tissue chamber, and the changes in isometric tension were recorded. RESULTS: SOD produced a greater relaxation in untreated-diabetic rings compared with control rings. ALA treatment partially reversed SOD-induced relaxation in diabetic aorta. Pretreatment of rings with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microm) inhibited SOD-induced relaxation. This effect of L-NAME was markedly observed in control and ALA-treated-diabetic rings compared with untreated-diabetic rings. SOD-induced relaxation was also inhibited by catalase (60 U/ml) in untreated-diabetic rings but not in ALA-treated-diabetic and control rings. Pretreatment with the cyclooxygenase inhibitor, indomethacin, or the catalase inhibitor, aminotriazole, had no effect on SOD-induced relaxation in any ring. CONCLUSION: Findings suggested that: (i) in normal physiological conditions, the relaxant effect of SOD is related to the inhibition of superoxide anion radicals (*O(2)(-))-induced endothelium-derived relaxing factor/nitric oxide (EDRF/NO) destruction in the rat aorta; (ii) in diabetic state, excess *O(2)(-) increasingly inhibits basal EDRF/NO, and the dismutation of excess *O(2)(-) to H(2)O(2) is enhanced by exogenous SOD. H(2)O(2) a vasorelaxant molecule, which probably accounts for the increased responsiveness of diabetic rings to exogenous SOD; and (iii) the reversal effect of in vivo ALA treatment on SOD-induced relaxation in diabetic aorta is probably linked with the elimination of *O(2)(-)/H(2)O(2), which mediates the recovery of basal EDRF/NO availability.

Amitrole↗
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

QT/corrected QT (QTc) intervals and QT/QTc dispersions in children with chronic renal failure.

UNLABELLED: We aimed to examine QT/corrected QT (QTc) intervals, QT/QTc dispersions (QTD/QTcD) and also the effect of different clinical and laboratory variables on these parameters in children with chronic renal failure. Serum biochemistry, 12-lead electrocardiogram, telecardiogram, and echocardiography were performed in 50 children with chronic renal failure (23 female and 27 male; aged 12.3+/-3.6 years, range 5 to 20 years). None of them had symptoms related to arrhythmias. When compared with a control group (372 children, aged 7 to 18 years, mean 12.4+/-2.6) patients with chronic renal failure had greater QT/QTc intervals and QT/QTc dispersion values (Patient: QT = 360.9+/-53.3; QTc = 438.5+/-33.2; QTD = 42.4+/-20.8; QTcD = 57.5+/-23.8; CONTROL: QT = 325.9+/-24.1; QTc = 398.7+/-19.7; QTD = 29.9+/-10.2; QTcD = 47.3+/-16.6; P<0.01). QT, QTc, and QTcD values were significantly greater in patients who had renal failure duration longer than 2 years. Patients who had impaired left ventricular systolic function on echocardiogram had greater QTc, QTD, and QTcD values. It was found that sex, cardiomegaly on chest X-ray, and left ventricular hypertrophy on echocardiogram were not related to these parameters. It is concluded that, impaired cardiac systolic function and longer renal failure duration are related to an increase in QT, QTc, QTD, and QTcD values and hence these variables may be risk factors for ventricular arrhythmias in uremic patients.

Adolescent↗
PubMed1999

Recurrent pericardial effusion due to gunshot wound of the heart in a hemodynamically stable child--a case report.

A 12-year-old girl presented with recurrent pericardial effusion due to firearm pellet injury to the left ventricle. The pellet was localized by two-dimensional echocardiography within the left ventricular apical wall. Since the patient was asymptomatic, left ventriculotomy was avoided to extract the pellet and only pericardial tube drainage was carried out. A slightly elevated blood lead level of the patient was alarming for potential subsequent lead poisoning due to retained pellets.

Child↗
PubMed1998

Congenital complete atrioventricular block in an infant with long QT syndrome.

A three months old patient with congenital complete atrioventricular block and prolonged QT interval syndrome is presented. Before admission she had had two syncopal attacks. During hospitalization she had an episode of torsade de pointes which was followed by ventricular fibrillation. After a successful cardiopulmonary resuscitation, a permanent epicardial ventricular pacemaker was implanted and she was discharged on propranolol therapy. She is now free of symptoms and doing well, 16 months after discharge.

Adrenergic beta-Antagonists↗
PubMed1997

Role of adenosine in the diagnosis and treatment of tachyarrhythmias in pediatric patients.

Tachyarrhythmias are common rhythm disturbances in infants and children. Despite the availability of diagnostic criteria arrhythmias are sometimes commonly misdiagnosed. Recent reports suggest that an endogenous purine nucleoside, adenosine, has a diagnostic effect in narrow QRS complex tachycardias, in addition to terminating supraventricular tachycardia involving the atrioventricular node. This report reviews the authors' experience with the use of adenosine for diagnosis of narrow and wide complex tachyarrhythmias in children. Adenosine was administered to 43 patients with several types of tachyarrhythmias (mean age, 8.3 +/- 5.24 years). Nineteen patients had structural or acquired heart disease. Of the 43 patients there were 28 (65%) several different types of narrow QRS complex tachycardia and 14 (33%) ventricular arrhythmias. One patient (2%) had long QT. Adenosine terminated supraventricular tachycardia, in 11 of 12 patients (92%), ventricular tachycardia in five of eight patients (63%), and transiently terminated premature ventricular contractions in two of six patients (33%). The diagnostic ability of adenosine was perfect in eight supraventricular tachycardia. In these eight cases the tachycardia mechanism was unclear before the administration of adenosine, which demonstrated three cases of sinus tachycardia, three of atrial flutter, one of atrial fibrillation and one of atrial fibrilloflutter. Confirmation of the primary diagnosis by adenosine was perfect in five tachyarrhythmias including three cases of atrial flutter, one of atrial fibrillation and one of ectopic atrial tachycardia. The average effective dose of adenosine was 212 micrograms/kg (range, 100-400 micrograms/kg). There were no serious side-effects except transient dyspnea, chest pain and flushing. These findings demonstrate adenosine to be helpful and safe in the diagnosis of tachyarrhythmias.

Adenosine↗
PubMedDate not supplied

Adenosine-sensitive right ventricular tachycardia in children.

Right ventricular outflow tachycardia is a distinct subgroup of idiopathic ventricular tachycardia (VT) with characteristic clinical and electrophysiologic properties. This study was planned to evaluate the effects of adenosine on idiopathic right ventricular tachycardia in children, and to assess the long-term efficacy of verapamil treatment. Diagnostic tests including electrocardiogram, chest roentgenogram, echocardiogram, exercise stress test and 24-hour ambulatory electrocardiographic monitoring were performed in each patient. Adenosine was administered in increasing amounts until an effective dose or a maximal dose of 300 micrograms/kg was reached. In adenosine-sensitive patients verapamil was given orally (3-10 mg/kg/day) for long-term suppression of arrhythmia. Seven patients with a mean age of 10.2 +/- 4.7 years were enrolled in the study. There were five male and two female patients. Six patients had VT, and one patient had frequent ventricular ectopic bests. Arrhythmia originated from the right ventricle in all patients. Adenosine was effective in terminating the arrhythmia in all patients, with a mean effective dose of 183 +/- 75 micrograms/kg. Favorable long-term results (mean follow-up period 17 +/- 8 months) were obtained with verapamil treatment at an average dose of 6.3 +/- 2.2 mg/kg. In conclusion, adenosine can be used effectively for termination of VT originating from the right ventricular outflow tract in children. In these patients verapamil may be considered as the drug of choice for long-term therapy.

Adenosine↗
PubMedDate not supplied

Poststreptococcal reactive arthritis: clinical course and outcome in 15 patients.

Patients with Group A beta-hemolytic streptococcal infection and articular disease, who do not fulfill the modified Jones criteria for diagnosis of acute rheumatic fever (ARF), have been classified as having poststreptococcal reactive arthritis (PSRA). We reviewed the clinical characteristics, laboratory findings and outcome of 15 patients with PSRA. None of these patients had clinical evidence of carditis. The pattern of joint involvement was variable and included arthritis in five patients and arthralgia in the remaining ten patients. Nine patients were treated with salicylates for one to 16 weeks; the others recovered spontaneously. Usually, the patients with arthralgia responded promptly to salicylates, while the response was poor in patients with arthritis. One patient with monoarthritis developed carditis nine months after his first arthritis attack. Another patient presenting with monoarthritis later had two additional episodes of poststreptococcal reactive arthralgia. It seems there is a wide spectrum of poststreptococcal rheumatic diseases, and patients with PSRA are also at risk for cardiac disease; therefore, prophylactic antibiotic therapy should be considered in these patients.

Anti-Bacterial Agents↗
PubMedDate not supplied

Impact of dialysis adequacy on cardiac function in pediatric CAPD patients.

BACKGROUND: Left ventricular hypertrophy is a major cause of morbidity and mortality among patients with chronic renal failure. Uremia-related risk factors play a fundamental role in its occurrence, thus better prognosis and prolonged survival can be attained by successful dialytic therapies. OBJECTIVE: To investigate whether dialysis adequacy has a beneficial effect on cardiac structure and function in children receiving continuous ambulatory peritoneal dialysis (CAPD). DESIGN: Cross-sectional study in the Pediatric Peritoneal Dialysis Unit of a university hospital. PATIENTS: Eighteen children, aged 13.3 +/- 2.8 years, being treated with CAPD, and 20 healthy age- and sex-matched control subjects were enrolled in this study. MAIN OUTCOME MEASURES: Echocardiographic evaluation was performed in all subjects. Dialysis adequacy indices [weekly urea (Kt/V) and creatinine clearance (TCCr)] were calculated in the dialysis group. RESULTS: Interventricular septal thickness, left ventricular (LV) posterior wall thickness, LV mass index (LVMI), and LV end systolic and diastolic dimensions were all found to be significantly higher in the CAPD group compared to the control subjects (p < 0.01). Ejection fraction and fractional shortening of the LV were not significantly different between the two groups. Mean Kt/V was 2.02 +/- 0.71 and mean TCCr was 58 +/- 33 L/wk/1.73 m2. There were significant negative correlations between dialysis adequacy indices and LV end systolic and diastolic dimensions (p < 0.05 and p < 0.001). Ejection fraction and fractional shortening were positively correlated with Kt/V (p < 0.01). Systolic and diastolic blood pressures were positively correlated with LVMI (r= 0.501 and r = 0.523). Significant inverse correlations between mean arterial pressure and both Kt/V and TCCr (r = -0.555 and r = -0.520) were detected. CONCLUSION: These data clearly document that cardiac structure and function are remarkably influenced by the uremic state and dialysis therapy in pediatric CAPD patients. The close relationships between echocardiographic findings and dialysis adequacy indices suggest that adequate dialysis has a beneficial effect on cardiac function via effective removal of toxic substances.

Adolescent↗
PubMedDate not supplied

Unilateral agenesis of the sternocleidomastoid muscle.

An eight-year-old girl with an asymmetrical appearance of the neck is presented. Physical examination and ultrasonographic (USG) findings revealed the absence of the patient's right sternocleidomastoid muscle.

Child↗
PubMedDate not supplied

Short- and intermediate-term efficacy of amiodarone in infants and children with cardiac arrhythmia.

The antiarrhythmic effect of amiodarone was examined in this retrospective study in a group of 20 patients with a mean age of 8.5 +/- 6.7 years (range 42 days to 20 years, median 9 years). Five patients with atrial flutter, one patient with atrial fibrillation, two patients with an intermediate rhythm between atrial flutter and atrial fibrillation, four patients with chaotic atrial tachycardia, three patients with atrioventricular reentry tachycardia, two patients with junctional ectopic tachycardia, and three patients with ventricular arrhythmias were treated with amiodarone. The mean duration of therapy was 9.1 +/- 12.3 months (range 1 month to 4 years). Before amiodarone treatment, 18 patients had been unresponsive to various antiarrhythmic drugs (range 1-8, median 2). Two patients received amiodarone as an initial therapy. It was administered orally at a dose of 10 mg/kg once per day for 10 days and then decreased to 5 mg/kg once per day. Amiodarone was effective in 16 patients (80%). Side effects occurred in three patients, including thyroid dysfunction, elevation of liver enzymes, and keratopathy. All side effects disappeared upon cessation of the therapy. We recommend amiodarone for the treatment of childhood arrhythmias, especially for the refractory types.

Administration, Oral↗