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Biomedical subjects

K Gücüyener

Publications and source records attributed to K Gücüyener.

At least 19 recordsLinked to original sources
PubMed2005

Brain perfusion assessed by 99mTc-ECD SPECT imaging in pediatric patients with neurally mediated reflex syncope.

BACKGROUND: The involvement of cardiogenic and neurogenic mechanisms in neurally mediated reflex syncope is well documented. In our previous studies in patients with neurally mediated reflex syncope, we have found evidence for differential regulation of the noradrenergic receptors in tilt-positive and tilt-negative patients. The present work concentrates on the observations of differences in regional brain perfusion using brain SPECT via injecting the patient at the completion of the tilt test. METHODS AND RESULTS: The following study was designed to assess the reduction and regional differences in cerebral blood flow by means of SPECT using technetium-99m labeled V-oxo-1,2-N1ethylenedylbisl-cysteine diethylester (ECD) in patients with an injection during tilt testing. Twenty patients with NMS were included in the study with a mean age of 12.2 years (age range; 8-16 years). HUT was positive in 10 patients and negative in 10 patients. When tilt (+) and tilt (-) were evaluated together, regional cortical/cerebellum ratios were ranging from 0.85 to 1.25 in different cortical areas with highest variability of perfusion index in left frontoparietal cortex. The lowest perfusion index values were observed in the left anterior frontal region followed by the left prefrontal-frontoparietal-anterior, parietal-orbito frontal, and anterior temporal regions where perfusion is predominantly supplied via the anterior and middle cerebral arteries, while these differences did not reach statistical significance in a single dominant region compared to the other regions examined using ANOVA (P > 0.05) with this sample size. Decreases in [99mTc]ECD uptake were more widespread regionally on the left hemisphere than were decreases in right side of the brain. However when tilt- and tilt+ groups were compared, perfusion was significantly lower in the right periinsular posterior parietal and temporal regions (P < 0.05) in tilt + group. CONCLUSION: These tilt induced regional differences in brain perfusion suggest the distinct roles of middle cerebral artery dominant territory-related vasodepressor compensation mechanisms in neurally mediated reflex syncope phenomena where cerebral lateralization of cardiac control and insular ischemia may play an important role.

Adolescent↗
PubMed2001

Autosomal recessive spastic ataxia of Charlevoix-Saguenay in two unrelated Turkish families.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay is an early onset form of hereditary spastic paraplegia with a peculiar clinical presentation. In addition to cerebellar findings which manifest first with ataxic gait in early life and spasticity, on an evolutionary basis, there is axonal neuropathy, prominent myelinated fibers in the optic fundus, and evidence of cerebellar atrophy that can be detected by cranial MRI. Intelligence is usually normal, however lower IQs have also been documented. This disorder mainly originates from the Charlevoix-Saguenay region of Quebec. Here, we report two Turkish families linked to the disease locus on chromosome 13 q12. There was homozygosity and segregation of disease haplotypes in both families. This form of spastic ataxia may be more common than originally presumed.

Adolescent↗
PubMed2000

Neonatal cerebral venous thrombosis coexisting with bilateral adrenal hemorrhage.

We report a case of severe perinatal asphyxia with both cerebral venous thrombosis and adrenal hemorrhage who survived with severe sequela including multicystic encephalomalasia, acquired microcephaly and blindness. Hematological investigations showed normal levels of anticardiolipin antibodies, protein C and S levels and activity, antithrombin III levels. Factor V Leiden mutation was negative. The adrenal hemorrhage resolved within three months with glucocorticoid therapy, the cerebral venous thrombosis resolved within two months without treatment. The literature on neonatal cerebral venous thrombosis is also reviewed.

Adrenal Gland Diseases↗
PubMed2000

Methyl-prednisolone in neurologic complications of Mycoplasma pneumonia.

In patients with Mycoplasma pneumonia extrapulmonary manifestations such as encephalitis, meningitis, cerebellar and brain stem involvement, cranial nerve lesions, peripheral neuropathy, polymyositis have been observed. We report a 16-year-old girl with M. pneumonia infection, acute behavioral changes and coma. Treatment with high dose methyl-prednisolone and clarithromycin led to rapid clinical improvement.

Adolescent↗
PubMed2000

The serum nitric oxide levels in patients with Duchenne muscular dystrophy.

Nitric oxide is formed in skeletal muscle by the neuronal type nitric oxide synthase and the signalling function of dystrophin and related compounds are in part mediated by nitric oxide. Duchenne muscular dystrophy, mdx mice and patients with Becker dystrophy demonstrated neuronal type nitric oxide synthase deficiency in muscle biopsy specimens. We have intended to find out whether the plasma nitric oxide levels show any abnormality in patients with Duchenne muscular dystrophy. Serum NO levels of Duchenne patients (4.191+/-2.82 micromol/l) were significantly lower than those of the control (39.53+/-19.43 micromol/l) and cerebral palsy (77.84+/-21.70 micromol/l) groups.

Cerebral Palsy↗
PubMed2000

Urinary nitric oxide in newborns with infections.

BACKGROUND: Neonatal sepsis is a major problem in newborn nurseries because of the difficulty in early diagnosis and because of the high morbidity and mortality. The objective of the present study was to investigate whether urinary nitric oxide (NO) levels could be useful for the diagnosis of infected newborns. METHODS: Newborns with suspected infection according to previously defined criteria between ages of 1-7 days and 8-30 days were included as the study groups (p) to be compared with age-matched healthy controls (c). Urine NO levels were assayed by Sievers NOA based on chemiluminescence and expressed as corrected for urine creatinine. RESULTS: 20 newborns with suspected infection at 1-7 days of age (group 1p) were compared with 45 healthy age-matched newborns (group 1c). 16 newborns with suspected infection at 8-30 days of age (group 2p) were compared with 15 healthy age-matched newborns (group 2c). The groups were similar with regard to birth weight and gestational age; however, the urinary NO levels in newborns with suspected infection at 1-7 days of age (80.25+/-60.68 micromol/mg creatinine) were higher than in healthy newborns (25.45+/- 19.35 micromol/mg creatinine). Similarly, newborns with suspected infection at 8-30 days of age had higher urinary NO levels (81.78+/- 40.43 micromol/mg creatinine) than age-matched controls (36.99+/-24.58 micromol/mg creatinine; p < 0.05). The sensitivity of urinary NO levels to detect infection was 50% in both age groups, and the specificity was 95% for 1-7 days of age and 93% for 8-30 days of age. Groups 1p and 2p were similar with regard to NO production. Altogether 12 patients had culture-proven sepsis, 11 patients had clinical sepsis, and 13 patients had other infections. The NO levels were similar in patients with culture-proven and clinical sepsis and higher than in patients with other infections. No difference was observed among NO levels of patients with gram-positive and gram-negative sepsis. CONCLUSIONS: Urinary NO levels which are quick and easy to measure are higher in infected newborns as compared with controls, and although the specificity is good, the sensitivity of the test is low, necessitating the use of another marker in addition to NO.

Biomarkers↗
PubMed2000

Evaluation of dysrhythmia in children with muscular dystrophy.

Myocardial involvement and dysrhythmia are common findings with muscular dystrophy and are among the leading causes of death. The authors evaluated rhythm and conduction abnormalities in children with muscular dystrophy by electrocardiography, signal-averaged electrocardiography, and Holter monitoring. Twenty-nine patients (mean age, 8 years) and 29 healthy control subjects were included in the study. Sixty-two percent of patients had electrocardiographic abnormalities defined as deep Q waves in V6, tall R waves in V1, and QRS axis deviation. The cardiomyopathy index was significantly greater in the patient group whereas QT and QTc dispersion values showed no significant difference. Holter monitoring revealed premature atrial and ventricular contractions more frequently than normal. However all were classified as Lown I and II. Mean heart rate was significantly higher in the patient group. The electrocardiograms of 41% of the patients showed late potentials. No relationship with these changes and cardiac function was observed. During the study, one patient died whose cardiomyopathy index was longer and had late potentials detected with signal-averaged electrocardiography. In conclusion, standard electrocardiography, cardiomyopathy index, signal-averaged electrocardiography, and Holter monitoring are valuable and reliable monitoring methods in children with muscular dystrophy.

Adolescent↗
PubMed2000

Moyamoya syndrome after radiation therapy for optic pathway glioma: case report.

We present a 4-year-old girl with neurofibromatosis-1 who developed moyamoya syndrome characterized by bilateral stenosis or occlusion of the distal internal carotid arteries and their branches, leading to the development of an abnormal vascular network. In light of a literature review, the postradiation vasculopathy of the moyamoya type and its relationship with neurofibromatosis-1 are discussed.

Abnormalities, Radiation-Induced↗
PubMed1999

Excitatory amino acids and taurine levels in cerebrospinal fluid of hypoxic ischemic encephalopathy in newborn.

The recent studies indicating the transiently enhanced expression of excitatory amino acid receptors in hypoxia vulnerable brain regions and the elevated concentration of aspartate and glutamate in cerebrospinal fluid of asphyxiated newborns strongly suggest the role of excitatory amino acids in hypoxic ischemic brain damage in the developing human brain. In this study, we compared the concentrations of glutamate, aspartate, taurine and glycine in the cerebrospinal fluid of asphyxiated infants with values of a healthy control group. The concentrations of aspartate (5.82 +/- 3.36), glutamate (1.76 +/- 1.0) and taurine (9.32 +/- 9.1) were significantly elevated in cerebrospinal fluid of asphyxiated infants (P < 0.05). When compared to the control group, the high levels of aspartate was correlated with the degrees of hypoxic-ischemic encephalopathy (HIE) and the varying outcome. The high levels of aspartate and glutamate in the asphyxiated patients adds further evidence to the role of excitotoxicity in hypoxic ischemic encephalopathy. The mental and motor development of the patients in asphyxiated group was followed for 3 years.

Aspartic Acid↗
PubMed1999

Tc-99m HMPAO brain perfusion imaging in young Down's syndrome patients.

Down's syndrome (DS) is characterized by moderate mental retardation and a variety of abnormalities involving multiple organ systems. There is a high incidence of Alzheimer's disease (AD) type dementia beyond the age of 35. In this study, single photon emission computed tomography (SPECT) brain perfusion imaging of young Down's syndrome patients was performed to define the perfusion pattern. Tc-99m HMPAO brain perfusion SPECT was performed on 17 young DS patients, aged 3-24 years (mean: 10.9+/-5.9 years). None of the patients had dementia symptoms. Brain perfusion scans were acquired 15 min after i.v. injection of 12 MBq/kg of Tc-99m HMPAO using a single head rotating gamma camera. Images were analyzed visually and semiquantitatively by defining side-to-side asymmetry index. Nine DS cases showed normal brain perfusion. Eight of the 17 cases revealed mostly unilateral parieto-temporal, parieto-occipital and frontal hypoperfusions. The side-to-side asymmetry indices for these visually interpreted regional brain perfusion abnormalities ranged from 6 to 15%. These findings revealing mostly unilateral parieto-temporal and frontal hypoperfusions may not be considered as predictive patterns of dementia related Alzheimer type perfusion deficits in DS. However, such findings may connect to other functional imaging studies related to the higher cortical dysfunction in mental retardation.

Adolescent↗
PubMed1999

Cerebrospinal fluid and serum nitric oxide levels in asphyxiated newborns.

Hypoxic-ischemic encephalopathy (HIE) is the result of a chain of events caused mainly by cytokines and nitric oxide (NO) release, which is later on followed by free oxygen radical injury. To investigate NO involvement in asphyxiated newborns, serum and cerebrospinal fluid (CSF) values of NO levels in 17 neonates with HIE were detected. Infants at or above 37 weeks of gestation were classified to have mild, moderate and severe HIE due to Sarnat and Sarnat. Samples obtained between 24 and 72 h of life were immediately frozen at -70 degrees C till the time of measurement by Sievers NOA. Five patients had mild, 6 patients had moderate and 6 patients had severe HIE, 4 in the severe HIE group also had multisystem involvement. The CSF NO levels were significantly higher in moderate and severe HIE groups compared to the mild HIE group (p = 0.028 and p = 0.018 respectively). Our results show that NO level increases in CSF with the severity of HIE between 24 and 72 h following asphyxia. According to the animal work, this is the time period where inducible NO synthase gets activated and could cause neurotoxicity, which might perhaps be prevented by interventions.

Asphyxia Neonatorum↗
PubMed1998

Nitric oxide in developing brain.

The role of NO in the neonatal brain, particularly during hypoxia and ischaemia has been studied extensively in animal models of focal and global ischaemia. The n-NOS and i-NOS activation have been found to be harmful whereas e-NOS activation has a neuroprotective effect in focal ischaemia (Fig. 1). The findings following global ischaemia are somewhat more controversial. Although all these studies clearly demonstrate that NO has an important role in the neonatal brain, it may be difficult to apply the results to humans for it is not clear when and which isoform of NOS gets activated following ischaemia in newborn infants. Also it is hard to determine the timing of intervention to inhibit or stimulate the production of NO in humans since we still do not know all the details about protective mechanisms of the human body. Some interventions may have a deleterious effect on some of those mechanisms. In addition, the relatively selective NOS inhibitors which are now used in animal experiments are not appropriate for human studies. New studies regarding the production of NO following ischaemia will be needed in newborns, together with the development of selective NOS inhibitors which can be used in humans. If the NO production follows the same pattern in humans as in animals at least the effects of i-NOS may be prevented either by selective inhibitors or by neuroprotective agents.

Brain↗
PubMed1998

Clinical observations in autosomal recessive spastic paraplegia in childhood and further evidence for genetic heterogeneity.

Among our 23 families (32 cases) with autosomal recessive hereditary spastic paraplegia (AR-HSP) all presenting in childhood, 9 families had the "pure" form. Occasional patients with this form had upper extremity hyperreflexia, pes cavus and sphincter disturbances, even at the early stages. Fourteen families were classified as the "complicated" types which manifested with mental retardation and cerebellar abnormalities. The evolution and severity was variable, but was generally consistent within families. Carriers (parents) did not manifest any signs. A total of 5 multiplex families with "complicated" type were used to test for a genetic heterogeneity to the region on chromosome 8p12-q13 where the "pure" AR-HSP has been mapped previously. No evidence in favor of linkage was detected in 3 of our families, thus we further supported genetic heterogeneity for AR-HSP.

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↗
PubMed1998

D2 receptor imaging with iodine-123-iodobenzamide brain SPECT in infants with hypoxic-ischemic brain injury.

UNLABELLED: The purpose of this study was to evaluate the striatal dopamine D2 receptor density in infants with perinatal hypoxic-ischemic brain injury (HIBI) using 123I-iodobenzamide (IBZM) brain SPECT and to correlate the findings with the severity of HIBI and neurologic outcome. METHODS: Twenty infants who were diagnosed to have perinatal HIBI were included in this study. They were classified as having mild (n = 6), moderate (n = 10) or severe (n = 4) HIBI according to their neurologic findings at birth using the criteria of Sarnat and Sarnat. Neurologic outcome of these infants was determined by serial neurologic examinations and the Denver developmental screening test; 10 infants recovered without any deficit and the remaining 10 were affected to a degree varying from motor impairment to cerebral palsy. All 20 infants were examined using 123I-IBZM brain SPECT at age 7.8 +/- 2.3 mo. Transaxial slices were obtained 2 hr after intravenous injection of 300 micro ci (11.1 MBq) 123I-IBZM and the activity ratios of striatal to occipital cortex (ST/OC) were calculated. RESULTS: The mean ST/OC ratios in patients with mild, moderate and severe HIBI (1.219 +/- 0.078, 1.097 +/- 0.069 and 0.813 +/- 0.140, respectively) were significantly different from each other (p = 0.001). The infants who recovered from HIBI without any neurologic sequelae had higher mean ST/OC ratios than the others (1.184 +/- 0.010 versus 0.969 +/- 0.160, p = 0.002). CONCLUSION: The results of this study show that in infants with HIBI, striatal D2 receptor density decreases as the severity of injury increases. The D2 receptor density is higher in infants who recover without neurologic deficits compared to those who are affected neurologically. Dopamine D2 receptor imaging can be used to assess the severity of HIBI in children.

Benzamides↗
PubMed1997

Biochemical alterations in neonatal hypoxic ischaemic brain damage.

Asphyxiated (n = 39) and control (n = 23) were elected for the study. Free radical-mediated lipid peroxidation, prostaglandin E2 and vitamin E levels were studied and the degree of hypoxic ischaemic encephalopathy was determined in each case. In the hypoxic group the concentration of prostaglandin E2 activity (P < 0.05) and malondialdehyde levels (P < 0.01) were significantly higher when compared to that of controls. The high vitamin E concentrations in the asphyxiated infants supports the role of oxygen free radicals in hypoxic ischaemic encephalopathy of newborns.

Asphyxia Neonatorum↗