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Dive into the research topics where Semai Bek is active.

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Featured researches published by Semai Bek.


Progress in Neuro-psychopharmacology & Biological Psychiatry | 2008

Potential effects of zinc on information processing in boys with attention deficit hyperactivity disorder.

Ozgur Yorbik; M. Fatih Ozdag; Abdullah Olgun; M. Guney Senol; Semai Bek; Serif Akman

PURPOSE The aims of the present study were to investigate the relationship between plasma zinc levels and amplitudes and latencies of P1, N2, and P3 in parietal and frontal areas in children with ADHD, and to compare these zinc levels and event-related potentials (ERPs) indices with controls. METHODS 28 boys with ADHD were divided into two groups according to plasma zinc levels: low zinc group (N=13, zinc level <80 microg/dL) and zinc non-deficient group (N=15, zinc level >or=80 microg/dL). ERP indices from parietal and frontal brain regions were recorded in children with ADHD and in 24 normal boys by using an auditory oddball paradigm. Plasma zinc levels were measured by an atomic absorption spectrophotometer. RESULTS The plasma zinc levels were significantly lower in both ADHD groups (means are 65.8 microg/dL in low zinc group and 89.5 microg/dL in zinc non-deficient group) than controls (mean: 107.8 microg/dL; both p values <0.017). In ADHD compared to controls, the amplitudes of P3 in frontal and parietal regions were significantly lower, and the latency of P3 in parietal region was significantly longer (all p values <0.017). In low zinc ADHD group compared to zinc non-deficient ADHD group, the latencies of N2 in frontal and parietal region were significantly shorter (all p values <0.017). In addition, there was a medium but significant positive correlation between plasma zinc levels and amplitude and latency of frontal N2 wave in ADHD. CONCLUSIONS These results can suggest that plasma zinc levels might have an effect on information processing in ADHD children, and lower zinc levels seem to affect N2 wave. Since N2 wave changes may reflect a different inhibition process, further studies are warranted to investigate the effect of zinc on inhibitory process in children with ADHD, and in low zinc and non-deficient ADHD groups.


Peptides | 2011

Time-dependent changes in the serum levels of prolactin, nesfatin-1 and ghrelin as a marker of epileptic attacks young male patients

Suleyman Aydin; Ersel Dag; Yusuf Ozkan; Özgür Arslan; Güray Koç; Semai Bek; Serkan Kirbas; Tayfun Kasikci; Dilek Abasli; Zeki Gökçil; Zeki Odabaşı; Zekiye Catak

A relationship between hormones and seizures has been reported in animals and humans. Therefore, the purpose of this study was to investigate the association between serum levels of prolactin, nesfatin-1 and ghrelin measured different times after a seizure or non-epileptic event and compared with controls. The study included a total of 70 subjects, and of whom 18 patients had secondary generalized epilepsy (SGE), 16 patients had primary generalized epilepsy (PGE), 16 patients exhibited paroxysmal event (psychogenic) and 20 healthy males were control subjects. The first sample was taken within 5min of a seizure, with further samples taken after 1, 24, and 48h so long as the patient did not exhibit further clinically observable seizures; blood samples were taken once from control subjects. Prolactin was measured immediately using TOSOH Bioscience hormone assays. Nesfatin-1 and ghrelin peptides were measured using a commercial immunoassay kit. Patients suffering from focal epilepsy with secondary generalization and primary generalized epilepsy presented with significantly higher levels of serum prolactin and nesfatin-1 and lower ghrelin levels 5min, 1 and 24h after a seizure than patients presenting with paroxysmal events (psychogenic) and control subjects; the data were similar but not statistically significant after 48h. The present study suggests that increased serum prolactin and nesfatin-1 concentrations, decreased ghrelin concentrations could be used as markers to identify patients that have suffered a recent epileptic seizure or other paroxysmal event (psychogenic).


Cell Biochemistry and Function | 2009

Analysis of paraoxonase 1 (PON1) genetic polymorphisms and activities as risk factors for ischemic stroke in Turkish population.

Birsen Can Demirdöğen; Seref Demirkaya; Semai Bek; Emel Arinç; Orhan Adali

Paraoxonase1 (PON1) is protective against the development of atherosclerosis, a risk factor for ischemic stroke. PON1 gene has one promoter region (−107T/C) and two coding region (192Q/R and 55L/M) polymorphisms that affect the levels and catalytic efficiency of the enzyme, respectively. In this study, we aimed to determine the importance of −107T/C, 192Q/R and 55L/M polymorphisms of PON1 gene and three PON1 activities (diazoxonase, paraoxonase, arylesterase) as risk factors for ischemic stroke.


Journal of the Neurological Sciences | 2008

Long-term follow-up of patients with adult-onset subacute sclerosing panencephalitis

Erdal Eroglu; Zeki Gökçil; Semai Bek; Ümit Hıdır Ulaş; Mehmet F. Ozdag; Zeki Odabasi

Subacute sclerosing panencephalitis (SSPE) is a rare infectious central nervous system disease with a poor prognosis. Nineteen patients, 18 males and one female, ranging in age from 18 to 22, mean 19.6+/-1.5 years with SSPE were evaluated. We treated 9 patients with oral isoprinosine and 10 patients with alpha-interferon plus oral isoprinosine and followed up for 16 to 160 months. Of the 9 patients treated with oral isoprinosine, 7 (77.7%) died, one stabilized, and one showed progression. Seven (70%) of 10 patients treated with alpha-interferon plus oral isoprinosine died, one showed progression, and stabilization was observed in two patients. Thus, we suggest that isoprinosine alone or in combination with intraventricular interferon did not change the prognosis in long-term follow-up periods.


Epilepsy Research | 2009

Is asymmetric dimethylarginine responsible for the vascular events in patients under antiepileptic drug treatment

Oguzhan Oz; Zeki Gökçil; Semai Bek; Erdinc Cakir; Zeki Odabaşı

Some recent studies indicated that administration of antiepileptic drugs (AEDs) is associated with occlusive vascular diseases. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide (NO) synthase inhibitor and increased plasma ADMA levels are associated with cardiovascular morbidity. We hypothesized that elevated plasma ADMA concentrations exist in patients receiving AEDs and administration of AEDs may result in an increased risk of occlusive vascular disease. Thirty five newly diagnosed epilepsy patients participated, patients were classified into two groups according to their antiepileptic drug regimen. In the first group patients were treated with valproic acid (VPA, n=17) (500-1500 mg/day), and in the second group with carbamazepine (CBZ, n=18) (400-1200 mg/day). ADMA levels significantly increased after treatment in both VPA (p=0.002) and CBZ (p=0.024) groups. Homocysteine levels increased in both groups, but the difference was significant only in VPA group (p=0.005). Serum folate levels did not differ in VPA group, but significantly decreased in CBZ group (p=0.006). Vitamin B(12) levels significantly increased in VPA group (p=0.001) but did not differ in CBZ group. Correlation analysis showed that the increases in ADMA and homocysteine levels in the VPA group were higher however the differences between the groups were insignificant. The correlations of the changes between ADMA and other parameters were all insignificant in both VPA and CBZ groups. In conclusion our data suggest that elevated ADMA levels may be responsible for the increased cardiovascular risk in patients with epilepsy under AED therapy.


Human & Experimental Toxicology | 2013

Cytochrome P4501A1 genotypes and smoking- and hypertension-related ischemic stroke risk:

B. Can Demirdöğen; A.Ç. Adali; Semai Bek; Şeref Demirkaya; Orhan Adali

This study aimed to determine whether the coding (A4889G) and noncoding region (T6235C) polymorphisms of the gene coding for cytochrome P4501A1 (CYP1A1), a xenobiotic-metabolizing enzyme responsible for the metabolism of carcinogenic polycyclic aromatic hydrocarbons, are involved in the pathogenesis of ischemic stroke in Turkish population. Study group consisted of 226 ischemic stroke patients and 113 controls. Genotypes were attained by allele-specific polymerase chain reaction (PCR) for A4889G and PCR/restriction fragment length polymorphism analysis for T6235C. Frequency of 6235C allele was significantly lower in patients (0.151) compared with controls (0.226, P = 0.015). Prevalence of hypertension and hypertension-associated ischemic stroke risk was lower for 6235C allele carriers. This allele decreased ischemic stroke risk twofold (adjusted odds ratio = 0.48, P = 0.005). There was almost no difference in 4889G allele frequencies in patients (0.445) and controls (0.425). However, prevalence of hypertension was lower in 4889G allele carriers when compared with the wild-type genotypes. In addition, risk of ischemic stroke for smoker and hypertensive individuals was lower when they have at least one 4889G allele. The present study demonstrated that CYP1A1 genetic variants contribute to interindividual variability in smoking- and hypertension-induced ischemic stroke risk.


Journal of Stroke & Cerebrovascular Diseases | 2013

Clinical Properties of Regional Thalamic Hemorrhages

Serhat Tokgoz; Seref Demirkaya; Semai Bek; Tayfun Kasikci; Zeki Odabasi; Gençer Genç; Mehmet Yücel

BACKGROUND Thalamic hemorrhage constitutes 6% to 25% of intracerebral hemorrhages. Vascular lesions affecting the thalamus may cause a variety of clinical symptoms. This retrospective study aims to evaluate localization of hemorrhage and clinical symptoms in patients with thalamic hemorrhage. METHODS One hundred and one patients with thalamic hemorrhage were examined retrospectively in our department. Hemorrhages were classified into 5 groups according to computed tomography: medial (thalamoperforate), anterolateral (tuberothalamic), posterolateral (thalamogeniculate), dorsal (posterior choroidal), and global. The relation between volume, localization, and penetration to adjacent structures/ventricles of hemorrhage and risk factors, clinical features, and prognosis were evaluated. RESULTS The study group included 101 patients. Eighty-two percent of the patients had hypertension, 19.8% had diabetes mellitus, 14.9% had cardiac disease, and 5.9% had chronic renal failure. Mean blood pressure was 173/101 mm Hg. Decreased Glasgow coma scale was significantly higher in the global hemorrhage group than in all regional groups (Chi-square, 10.54; P = .002). Medial group hemorrhages had a significantly higher rate than anterolateral, posterolateral, and dorsal intraventricular expansion. Out of speech disorders, 49% of patients had a right thalamic lesion (especially dysarthria) and 51% of patients had a left thalamic lesion (mostly aphasia). CONCLUSIONS In the study, we detected that the most important risk factor in thalamic hemorrhage is hypertension. The prognosis is worse in global and medial group hemorrhages, especially those which rupture to the ventricle, than the other groups. Thalamic lesions cause a variety of symptoms, including forms of aphasia, such as crossed dextral aphasia.


Cytotherapy | 2009

Reinnervation cannot be interpreted as an indicator of electrophysiologic improvement in amyothrophic lateral sclerosis

Semai Bek; Tayfun Kasikci; Zeki Odabasi

Denervation and reinnervation comprise a dynamic process that begins in the early periods of amyothrophic lateral sclerosis and lasts until the final individual motor neuron dies. A dynamic process like denervation-reinnervation that is found in the natural course of the disease can not be presented as a neurophysiologic measure. Other parameters, such as motor unit number estimation, compound muscle action potential amplitude and neurophysiologic index, seem more appropriate for therapeutic trials.


Multiple Sclerosis International | 2012

Strength-Duration Time Constant in Peripheral Nerve: No Abnormality in Multiple Sclerosis

Gençer Genç; Semai Bek; Tayfun Kasikci; Ümit Hıdır Ulaş; Seref Demirkaya; Zeki Odabasi

Objectives. To investigate the properties of the strength-duration time constant (SDTC) in multiple sclerosis (MS) patients. Methods. The SDTC and rheobase in 16 MS patients and 19 healthy controls were obtained following stimulation of the right median nerve at the wrist. Results. SDTC and rheobase values were 408.3 ± 60.0 μs and 4.0 ± 1.8 mA in MS patients, versus 408.0 ± 62.4 μs and 3.8 ± 2.1 mA in controls. The differences were not significant in SDTC or rheobase values between the patients and controls (P = 0.988 for SDTC and P = 0.722 for rheobase). Conclusion. Our study showed no abnormality in relapsing remitting MS patients in terms of SDTC, which gives some indirect information about peripheral Na+ channel function. This may indicate that alterations in the Na+ channel pattern in central nervous system (CNS) couldnot be shown in the peripheral nervous system (PNS) in the MS patients by SDTC. The opinion that MS can be a kind of channelopathy might be proven by performing other axonal excitability tests or SDTC in progressive forms of MS.


Neuro-Ophthalmology | 2009

Gabapentin and Superior Oblique Myokymia

Semai Bek; Tayfun Kasikci; Gençer Genç; Zeki Odabasi

Superior oblique myokymia (SOM) is an uncommon disorder characterized by episodic monocular oscillopsia. Though the mechanism of SOM is not fully established, recent reports focus on the role of vascular compression. Several medications have been reported to be of benefit but a standard protocol for SOM has not been established. This case report documents a complete symptom relief in SOM with a documented vascular compression using gabapentin.

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Zeki Odabasi

University of Alabama at Birmingham

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Gençer Genç

Military Medical Academy

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Zeki Gökçil

Military Medical Academy

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Erdal Eroglu

Military Medical Academy

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Zeki Odabaşı

Military Medical Academy

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Mehmet Yücel

Military Medical Academy

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Orhan Adali

Middle East Technical University

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