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Biomedical subjects

H Koçak

Publications and source records attributed to H Koçak.

At least 19 recordsLinked to original sources
PubMed2007

Early and late effects of hyperbaric oxygen treatment on oxidative stress parameters in diabetic patients.

Exposure to hyperbaric oxygen leads to increased amount of reactive oxygen species (ROS) that are derived from various sources. After the discovery that ROS can function as signaling molecules, the idea of ROS being hazardous to biological tissues has been challenged. The aim of this study was to examine the changes in oxidative stress parameters in diabetics undergoing hyperbaric oxygen therapy (HBOT) due to foot ulcers. Twenty patients, who received HBOT for diabetic foot ulcers, were included in the study. Blood samples were taken before HBOT and 30 min after exit from the chamber, on the day of the first and the fifteenth HBOT sessions. They were used for the determinations of malondialdehyde (MDA), 8-isoprostane and advanced oxidation protein products (AOPPs). 8-Isoprostane and AOPP levels were not altered significantly after the first HBOT session, while both were increased on the fifteenth day (p<0.05). MDA was significantly increased only after the first HBOT session, and remained unchanged on the fifteenth day (within-day variations). Plasma AOPP levels were lowered significantly after fifteen consecutive HBOT sessions (between-day variations). Decreased AOPP levels suggest that increased oxygenation of tissues due to HBO therapy may activate some endogenous factors that prevent hazardous effects of the disease itself.

Adult↗
PubMed2005

Cystatin-C and creatinine as indices of glomerular filtration rate in the immediate follow-up of renal transplant patients.

Serum cystatin-C (cys-C), creatinine (Cr), C-reactive protein (CRP) and amyloid A have been shown to provide useful information for renal function following transplantation. In this study, we wanted to evaluate the impact of these parameters as markers of the glomerular filtration rate (GFR) on the third and seventh days of the post-transplantation period. Cys-C was determined by the particle-enhanced immunoturbidimetric assay, and serum amyloid A (SAA) by the sandwich-enzyme immunoassay kit. Cr and CRP concentrations were measured by the Cobas Integra 400 autoanalyser. The patients (n=35) were followed with daily repetitive measurements of serum Cr and urine output per hour, and with Doppler ultrasonography against the risk of rejection. Statistical evaluations were made using the ANOVA and Pearson's test. Serum cys-C and Cr levels on both the 3rd and 7th days after transplantation were lower than those of pretransplantation values (P<0.001). The Cr/cys-C ratio was decreased on the 3rd day of the post-transplantation period, and kept declining on the 7th day. This ratio was high only in the patient with an acute rejection episode. None of the patients with high pretransplant CRP levels had a rejection episode during a six-month follow-up. SAA concentrations were found to be higher than the pretransplant values in the early post-transplant period. Cys-C had good sensitivity to estimate the renal function in the very early period of transplantation, but its value as a marker of GFR was decreased at the end of first week. As none of the 34 patients had a rejection episode, the observed rise in SAA and CRP levels is not specific to rejection.

Adolescent↗
PubMed2005

Hyperhomocysteinaemia as a risk factor for deep-vein thrombosis.

OBJECTIVE: Several studies have shown a relation between hyperhomocysteinaemia and vascular disease. To assess the risk of deep-vein thrombosis (DVT) associated with hyperhomocysteinaemia, we studied plasma homocysteine levels in patients with deep-vein thrombosis and in normal control subjects. MATERIALS AND METHODS: We measured plasma homocysteine levels in 48 patients with deep-vein thrombosis and in 33 healthy controls matched to the patients according to age and sex. Plasma homocysteine levels were measured with high performance liquid chromatography and fluorescence detection. Hyperhomocysteinaemia was defined as a plasma homocysteine level about 15 micromol/L in both groups. The diagnosis of all patients with deep-vein thrombosis (n=48) was verified by Doppler ultrasonography. RESULTS: Plasma homocysteine levels were found to be increased in the deep-vein thrombosis group compared the control group (p<0.001, t-test). The mean plasma homocysteine level in the patients was 17.1 SD 5.13 micromol/L (range 6.4-31.3), and that in the controls was 9.0 SD 1.27 micromol/L (range 6.0-11.5). The association between elevated homocysteine levels and venous thrombosis was stronger among men than among women. CONCLUSIONS: The increased plasma homocysteine levels we have observed may have a causative role in the development of deep-vein thrombosis.

Adult↗
PubMed2005

Subxiphoid pericardiostomy in the management of pericardial effusions: case series analysis of 368 patients.

OBJECTIVE: To assess the effectiveness of subxiphoid pericardiostomy in the treatment and diagnosis of pericardial effusions. METHODS: 368 patients who underwent subxiphoid pericardiostomy and tube drainage for cardiac tamponade, moderate to severe pericardial effusion, or suspicious bacterial aetiology were retrospectively analysed. Biopsies of the pericardium and fluid samples for diagnostic tests were obtained from each patient. RESULTS: The mean age of the patients was 38.4 years, and the male to female ratio was 220:148. The pericardial effusion was classified by echocardiography as severe in 53% of the patients, moderate in 43%, and mild in 4%. The incidence of cardiac tamponade was 25%. Myocardial injury requiring sternotomy occurred as an operative complication in 0.8% of the patients and recurrent effusion necessitating further surgical intervention developed in 10% of patients. Histopathological examination and the polymerase chain reaction of specimens of pericardium and fluid were helpful for establishing a diagnosis in 90% of patients with malignancy and 92% of patients with tuberculous pericarditis. The overall 30 day mortality rate was 0.8%. Patients were followed up for at least one year. Pericardial constriction requiring pericardiectomy developed in 3% of the patients. CONCLUSIONS: Pericardial effusions of various causes can be safely, effectively, and quickly managed with subxiphoid pericardiostomy in both adults and children.

Adolescent↗
PubMed2002

Effect of exogenous melatonin on ethanol-induced changes in Na(+),K(+)- and Ca(2+)-ATPase activities in rat synaptosomes.

In the present study, the effects of acute ethanol (EtOH) toxicity and of exogenous melatonin (MLT) on this toxicity were examined by measuring membrane-bound ATPases and acetylcholinesterase activities in rat synaptosomal membranes. The concentrations of plasma alpha-tocopherol and adrenal ascorbic acid (AA) were also measured. Synaptosomal Na(+),K(+)-ATPase and Ca(2+)-ATPase activities were significantly depressed in acute EtOH-intoxicated rats compared with controls, while acetylcholinesterase activity remained unaltered. Pretreatment with MLT (10 mg/kg) prior to acute EtOH administration prevented EtOH-induced inhibition of ATPases. Adrenal AA and plasma alpha-tocopherol levels were also depressed regardless of MLT pretreatment. MLT treatment alone affected neither membrane-bound enzyme activities nor tissue and blood levels of vitamins C and E. It is concluded that acute EtOH intoxication disturbs neural transport functions through the membrane-bound ATPase activity depression. Reduced AA and alpha-tocopherol levels may contribute to the neurodegenerative effects of EtOH. However, pretreatment with a high dose of MLT before EtOH administration may be beneficial to prevent EtOH-induced toxicity on ATPase-mediated neural transport functions.

Animals↗
PubMed2002

Comparison of the topical haemostatic agents for the prevention of suture hole bleeding. An experimental study.

OBJECTIVE: using a rabbit vascular graft model we investigated the use of fibrin glue (FG), gelatin-resorcinol-formaldehyde (GRF), and collagen (C) as a means of reducing suture hole bleeding. MATERIALS AND METHODS: twenty-eight rabbits were divided into four groups: fibrin glue, gelatin-resorcinol-formaldehyde, collagen and control. A 1 cm incision was made in the abdominal aortic wall of each animal. Incisions were covered with a polytetrafluoroethylene patch sutured with a 7-0 polypropylene. Fibrin Glue, GRF, and C were applied to cover suture holes in the groups 1, 2 and 3, respectively, but nothing in controls (group 4). The fibrin clot was allowed to achieve strength for 3 minutes before the clamps were reopened. After reopening the clamps, blood was collected from the surgical site using a syringe for a total of 2 min. RESULTS: mean blood loss was significantly lower in the FG, GRF, and C compared with control group (p=0.0022, p=0.0022, and p=0.0017, respectively). The volume of blood lost and the time of haemostasis in the group 1 (FG) was less than those in groups 2 and 3 (GRF and C, respectively) (p=0.001). The haemostasis (defined 2 min later) was achieved only in group 1 (FG) (p=0.00067). CONCLUSIONS: FG, GRF and C all reduce blood loss. Fibrin glue containing factor XIII was the most effective.

Administration, Topical↗
PubMed2001

Evaluation of leukocyte arylsulfatase-A activity in patients with breast cancer and benign breast disease.

This study was planned to evaluate the feasibility of using the assay of leukocyte arylsulfatase-A (AS-A) activity as a non-invasive diagnostic tool in patients with benign and malignant breast disease. The leukocyte AS-A activity of a total of 81 women was analyzed, including 28 healthy women, 29 women with benign breast disease (BBD) and 24 patients with primary breast cancer (BC). The mean leukocyte AS-A activity in patients with BBD was slightly higher (14.3%) that observed in the healthy subjects, but the difference was not statistically significant. In patients with BC the enzyme activity was significantly higher than in the healthy subjects (60.3%, P<0.05) and in the benign group (40.2%, P<0.05). In addition, since no significant differences have been observed between premenopausal patients and their controls, it is suggested that the measurement of leukocyte AS-A activity may not be a reliable test for differential diagnosis of benign and malignant proliferation in mammary glands due to the possible interfering effect of gonadal hormones on AS-A activity. In contrast, since peri- and postmenopausal BC patients have negligible or no gonadal activity function, the elevation in the activity of leukocyte AS-A in these age groups of patients may only be expected to originate from malignant proliferation. Based on our results, it is concluded that in patients in whom high leukocyte AS-A activities were observed the possibility of the presence of malignancy might also be high. Therefore, this test might be valuable as a non-invasive biochemical technique in combination with other established markers for the identification of masses in the breast.

Adult↗
PubMed2001

The effect of aminoguanidine on diabetes-induced inactivation of kidney Na(+),K(+)- ATPase in rats.

We studied the effect of aminoguanidine (AG), an inhibitor of advanced glycation product formation, on diabetes-induced oxidative damage. Renal cortex Na(+),K(+)- ATPase was chosen for study as a potential cellular target of oxygen radicals. In this study, the enzyme activity was reduced while malondialdehyde (MDA) and carbonyl levels were enhanced but sulphydryl (SH) level remained unchanged in the renal cortex in diabetic animals. Treatment of diabetic rats with AG had no significant effect on diabetes-induced impairments of enzyme activity and MDA but the carbonyl level readjusted to control level in the kidney. These results show that AG treatment at that dose did not exhibit profound antioxidant properties even if carbonyl stress was ameliorated by this treatment.

Animals↗
PubMed2001

The effect of vascular endothelial growth factor on angiogenesis: an experimental study.

OBJECTIVE: to evaluate the effects of exogenous vascular endothelial growth factor (VEGF) on angiogenesis in a rabbit model of persistent hind limb ischaemia. MATERIALS AND METHODS: ischaemia was induced in the hind limbs of 42 New Zealand white rabbits divided into six groups, each of 7 animals. Group 1a and 1b received intramuscular injections of 1 and 2 mg VEGF/day, respectively, into the ischaemic hind limb for 10 days beginning on postoperative 11th day, and group 1c received IM injections of saline only. Group 2a and 2b received similar regimen of VEGF, but administered intra-arterially. Group 2c served as controls. Perfusion of the ischaemic limb was evaluated by thigh blood pressure and thigh circumference at 10, 25 and 40 days following limb ischaemia in all animals and by digital subtraction angiography, perfusion scans, histological examination of capillary density in 2 animals from each group. RESULTS: thigh pressure index and thigh circumference improved significantly in the VEGF treated animals (Groups 1a,b and 2a,b). Collateral formation, as assessed by angiography, scintigraphy and by histological examination, indicated marked formation of collaterals in the VEGF treated animals as compared with the controls. This was most pronounced in groups receiving the highest dose of VEGF. CONCLUSION: these data suggest that VEGF promotes angiogenesis, that the route of administration is unimportant, but that a dose-response relationship is present in this experimental ischaemic hind limb model.

Angiography, Digital Subtraction↗
PubMed2001

Infected cardiac hydatid cyst.

A 24 year old woman presented with chest pain and palpitation. The presence of a semisolid mass-an echinococcal cyst or tumour-in the left ventricular apex was diagnosed by echocardiography, computed tomography, and magnetic resonance imaging. The infected cyst was seen at surgery. The cyst was removed successfully by using cardiopulmonary bypass with cross clamp.

Adult↗
PubMed2000

Sex-dependent changes in blood-brain barrier permeability and brain NA(+),K(+) ATPase activity in rats following acute water intoxication.

To understand the increased susceptibility of the development of serious complications to hypoosmotic hyponatremia in young females, we examined the resistance of blood brain barrier (BBB) permeability to water along with the synaptosomal Na(+),K(+)ATPase activity in both sexes of rats during acute water intoxication. Four groups of rats were used: Group I and II were normal female and male rats injected with only Evans-blue. Group III and IV were water intoxicated female and male rats respectively. BBB permeability in female rats was found to be increased following acute water intoxication. In contrast, synaptosomal Na(+),K(+)ATPase activities in both water intoxicated male and female rats were found significantly lower than those in control rats. But inhibition in enzyme activity in synaptosomes from water intoxicated female rats was more pronounced than those of corresponding male rats. Our results concluded that female sex steroids may be responsible for the highly significant decrease in synaptosomal Na(+),K(+)ATPase activity and increased BBB permeability in female rats following water intoxication.

Acute Disease↗
PubMed2000

Testis glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase activities in aminoguanidine-treated diabetic rats.

Severe steroidogenic and spermatogenic alterations are reported in association with diabetic manifestations in humans and experimental animals. This study was planned to determine whether oxidative stress is involved in diabetes-induced alterations in the testes. Diabetes was induced in male rats by injection of 50 mg/kg of streptozotocin (STZ). Ten weeks after injection of STZ, levels of selenium and activities of selenium dependent-glutathione peroxidase (GPx) and phospholipid hydroperoxide glutathione peroxidase (PHGPx) were measured in rat testis. Lipid and protein oxidations were evaluated as measurements of testis malondialdehyde (MDA) and protein carbonyl levels, respectively. Testis sulfydryl (SH) levels were also determined. The control levels of GPx and PHGPx activities were found to be 46.5 +/- 6.2 and 108.8 +/- 19.8 nmol GSH/mg protein/min, respectively. Diabetes caused an increase in testis GPx (65.0 +/- 21.1) and PHGPx (155.9 +/- 43.1) activities but did not affect the levels of selenium or SH. However, the testis MDA and protein carbonyl levels as markers of lipid and protein oxidation, respectively, did not increase in the diabetic group. Aminoguanidine (AG) treatment of diabetic rats returned the testis PHGPx activity (136.5 +/- 24.9) to the control level but did not change the value of GPx activity (69.2 +/- 17.4) compared with diabetic group. MDA and protein carbonyl levels in testis were not affected by AG treatment of diabetic rats, but interestingly AG caused SH levels to increase. The results indicate that reactive oxygen radicals were not involved in possible testicular complications of diabetes because diabetes-induced activations of GPx and PHGPx provided protection against oxidative stress, which was reported to be related to some diabetic complications.

Animals↗
PubMed2000

Genotype-phenotype correlation in a large group of Turkish patients with familial mediterranean fever: evidence for mutation-independent amyloidosis.

OBJECTIVES: Differences in clinical manifestations of familial Mediterranean fever (FMF) between different ethnic groups have been documented. The FMF gene was recently cloned and four missense mutations (Met694Val, Met680Ile, Val726Ala, and Met694Ile) that account for a large percentage of the patients were identified. The results of initial mutation studies have led to the hypothesis that phenotypic variation of the disease may be attributable to the existence of some of these mutations. The purpose of this study was to evaluate whether this phenotypic variation is associated with the existence of particular mutations in Turkish FMF patients living in Turkey. METHODS: Four missense mutations and genotype-phenotype correlation were investigated in 167 Turkish FMF patients. The patients were grouped according to the presence of the Met694Val and the Met680Ile mutations, and 12 clinical parameters were compared between the groups. RESULTS: The presence of the Met694Val mutation was not found to be associated with a severe form of the disease or the development of amyloidosis. Arthritis frequency was found to be lower in the patients with homozygous Met680Ile mutation. CONCLUSIONS: None of the four missense mutations is associated with a severe disease or the development of amyloidosis in Turkish FMF patients living in Turkey. The influence of unknown environmental factors and/or the presence of other genetic changes are necessary to explain the phenotypic variation of the disease and the development of amyloidosis.

Adolescent↗
PubMed1999

Familial Mediterranean fever and acute rheumatic fever: a pathogenetic relationship?

The frequency of acute rheumatic fever (ARF) in patients with familial Mediterranean fever (FMF) was documented and the effects of preceding streptococcal infections on the exacerbation of FMF were determined. In the first part of the study, 162 individuals with FMF were investigated for a history of ARF in a retrospective study. In the second part of the study, antistreptolysin-O (ASO) titres were measured in 130 individuals with FMF. Thirty-six patients had an arthritic attack (group A1), 55 patients had a typical FMF attack without arthritis (group A2) and 39 patients were in the attack-free interval (group B) during the investigation. Nine patients with FMF (5.5%) were considered to have ARF and three of them (1.85%) also had rheumatic heart disease. This prevalence of rheumatic heart disease in FMF is higher than that of the normal population (0.65%) reported in Turkey. Elevated ASO titres were found in 75%, 42% and 38% of the patients in groups A1, A2 and B, respectively. These percentages were found to be significantly higher in group A1 than in both groups A2 (p<0.01) and B (p<0.01). We concluded that patients with FMF might be more prone to the late complications of streptococcal infections.

Acute Disease↗
PubMed1999

Familial Mediterranean fever--renal involvement by diseases other than amyloid.

BACKGROUND: In patients with familial Mediterranean fever (FMF) renal involvement is usually in the form of AA amyloidosis. There is increasing evidence that renal involvement may be due to diseases other than amyloid as well. METHODS: Amongst 302 children with FMF we observed and followed 28 with typical clinical and laboratory features of vasculitis. The diagnosis of FMF was established according to the Tel Hashomer criteria. RESULTS: Polyarteritis nodosa, protracted febrile attacks and Henoch-Schönlein purpura were diagnosed in 4, 13, and 11 patients, respectively. The presentation was often difficult to distinguish from FMF attacks, but protracted febrile attacks lasting several weeks, hypertension, thrombocytosis, and dramatic responses to corticosteroid therapy that were observed in many cases were different from what is observed in classical FMF. CONCLUSIONS: We suggest that FMF, perhaps as a consequence of impaired control of inflammatory responses, predisposes to vasculitis with renal involvement.

Child↗