Researcher:
Gürses, Rabia Candan

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Rabia Candan

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Gürses

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Gürses, Rabia Candan

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2016 - 201942020 - 202212

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Now showing 1 - 10 of 16
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    Effects of beta-hydroxybutyrate on brain vascular permeability in rats with traumatic brain injury
    (Wiley, 2016) Orhan, Nurcan; Yılmaz, Canan Uğur; Ekizoğlu, Oğuzhan; Ahıshalı, Bülent; Küçük, Mutlu; Arıcan, Nadir; Elmas, İmdat; Gürses, Candan; Kaya, Mehmet; Gürses, Rabia Candan; Faculty Member; School of Medicine; 110149
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    The strategies of drug targeting into the brain through the blood-brain barrier in drug-resistant epilepsy
    (Wiley, 2019) Yılmaz, Canan Uğur; Emik, Serkan; Orhan, Nurcan; Arican, Nadir; Temizyürek, Arzu; Ahıshalı, Bülent; Akcan, Uğur; Atış, Müge; Gürses, Rabia Candan; Kaya, Mehmet; Other; Faculty Member; PhD Student; PhD Student; Faculty Member; Faculty Member; School of Medicine; School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; School of Medicine; School of Medicine; 357912; 9509; N/A; 346431; 110149; 10486
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    Elimination of pseudo-HFOs in iEEG using sparse representation and random forest classifier
    (Verasonics, 2022) Besheli, Behrang Fazli; Sha, Zhiyi; Henry, Thomas; Gavvala, Jay R; Ince, Nuri F.; N/A; Karamürsel, Sacit; Gürses, Rabia Candan; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 19597; 110149
    High-Frequency Oscillation (HFO) is a promising biomarker of the epileptogenic zone. However, sharp artifacts might easily pass the conventional HFO detectors as real HFOs and reduce the seizure onset zone (SOZ) localization. We hypothesize that, unlike pseudo-HFOs, which originates from artifacts with sharp changes or arbitrary waveform characteristic, real HFOs could be represented by a limited number of oscillatory waveforms. Accordingly, to distinguish true ones from pseudo-HFOs, we established a new classification method based on sparse representation of candidate events that passed an initial detector with high sensitivity but low specificity. Specifically, using the Orthogonal Matching Pursuit (OMP) and a redundant Gabor dictionary, each event was represented sparsely in an iterative fashion. The approximation error was estimated over 30 iterations which were concatenated to form a 30-dimensional feature vector and fed to a random forest classifier. Based on the selected dictionary elements, our method can further classify HFOs into Ripples (R) and Fast Ripples (FR). In this scheme, two experts visually inspected 2075 events captured in iEEG recordings from 5 different subjects and labeled them as true-HFO or Pseudo-HFO. We reached 90.22% classification accuracy in labeled events and a 21.16% SOZ localization improvement compared to the conventional amplitude-threshold-based detector. Our sparse representation framework also classified the detected HFOs into R and FR subcategories. We reached 91.24% SOZ accuracy with the detected R+FR events. Clinical Relevance---This sparse representation framework establishes a new approach to distinguish real from pseudo-HFOs in prolonged iEEG recordings. It also provides reliable SOZ identification without the selection of artifact-free segments.
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    The effects of lipopolysaccharide on the disrupted blood-brain barrier in a rat model of preeclampsia
    (Elsevier Science Bv, 2018) Kucuk, Mutlu; Yilmaz, Canan Ugur; Orhan, Nurcan; Ahishali, Bulent; Arican, Nadir; Elmas, Imdat; Gürses, Rabia Candan; Kaya, Mehmet; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 110149; 10486
    Background: Preeclampsia is a disorder characterized by high blood pressure and often proteinuria during pregnancy. It is known that a subseptic dose of bacterial lipopolysaccharide (LPS) induces production of proinflammatory cytokines, and possibly increasing the risk for developing preeclampsia. We investigated the effects of LPS on the blood-brain barrier (BBB) integrity in pregnant rats with N (omega)-nitro-L-arginine methyl ester (L-NAME) induced preeclampsia. Methods: Starting from the 10th day of gestation, pregnant rats were given L-NAME for 10 days to produce hypertension and proteinuria. Animals were then treated with a single injection of LPS on the 19th day of pregnancy. Arterial blood pressure and proteinuria were measured on the day of the experiment, which was 24 hours after the LPS injection. The BBB integrity was assessed by using Evans blue (EB) and horseradish peroxidase (HRP) tracers. Results: Proteinuria was observed in varying degrees, and the arterial blood pressure increased in L-NAME-treated pregnant rats (P < .01). The overall brain EB content did not increase in these preeclamptic rats when compared to pregnant animals, and LPS treatment also did not change EB content. Ultrastructurally, frequent vesicles containing HRP reaction products were observed in the capillary endothelial cells in the cerebral cortex and hippocampus of pregnant rats treated with L-NAME (P < .01). However, LPS did not change the amounts of HRP that mainly accumulated in brain capillary endothelial cells of these animals. Conclusion: Our results suggest that, in this experimental setting, LPS does not change the severity of BBB disruption observed in preeclamptic animals.
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    Slow repetitive transcranial magnetic stimulation in refractory juvenile myoclonic epilepsies
    (Academic Press Inc Elsevier Science, 2020) Özek, Sibel Üstün; Bebek, Nerses; Baykan, Betül; Gökyiğit, Ayşen; Öge, A. Emre; Gürses, Rabia Candan; Faculty Member; School of Medicine; 110149
    Objective: The objective of the study was to investigate the effects of slow repetitive transcranial magnetic stimulation (rTMS) on patients with refractory juvenile myodonic epilepsy (JME).
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    A sparse representation strategy to eliminate pseudo-HFO events from intracranial EEG for seizure onset zone localization
    (Institute of Physics (IOP) Publishing, 2022) Besheli, Behrang Fazli; Sha, Zhiyi; Gavvala, Jay R.; Quach, Michael M.; Curry, Daniel J.; Sheth, Sameer A.; Francis, David J.; Henry, Thomas R.; Ince, Nuri F.; N/A; Karamürsel, Sacit; Gürses, Rabia Candan; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 19597; 110149
    Objective. High-frequency oscillations (HFOs) are considered a biomarker of the epileptogenic zone in intracranial EEG recordings. However, automated HFO detectors confound true oscillations with spurious events caused by the presence of artifacts. Approach. We hypothesized that, unlike pseudo-HFOs with sharp transients or arbitrary shapes, real HFOs have a signal characteristic that can be represented using a small number of oscillatory bases. Based on this hypothesis using a sparse representation framework, this study introduces a new classification approach to distinguish true HFOs from the pseudo-events that mislead seizure onset zone (SOZ) localization. Moreover, we further classified the HFOs into ripples and fast ripples by introducing an adaptive reconstruction scheme using sparse representation. By visualizing the raw waveforms and time-frequency representation of events recorded from 16 patients, three experts labeled 6400 candidate events that passed an initial amplitude-threshold-based HFO detector. We formed a redundant analytical multiscale dictionary built from smooth oscillatory Gabor atoms and represented each event with orthogonal matching pursuit by using a small number of dictionary elements. We used the approximation error and residual signal at each iteration to extract features that can distinguish the HFOs from any type of artifact regardless of their corresponding source. We validated our model on sixteen subjects with thirty minutes of continuous interictal intracranial EEG recording from each. Main results. We showed that the accuracy of SOZ detection after applying our method was significantly improved. In particular, we achieved a 96.65% classification accuracy in labeled events and a 17.57% improvement in SOZ detection on continuous data. Our sparse representation framework can also distinguish between ripples and fast ripples. Significance. We show that by using a sparse representation approach we can remove the pseudo-HFOs from the pool of events and improve the reliability of detected HFOs in large data sets and minimize manual artifact elimination.
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    Ictal asystole in a patient with right temporal lobe epilepsy
    (Taiwan Soc Cardiology, 2022) Kaya, Caglar; Ozkan, Hulya; Yilmaztepe, Mustafa; Aksoy, Yuksel; Baysal-Kirac, Leyla; Gürses, Rabia Candan; Faculty Member; School of Medicine; Koç University Hospital; 110149
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    Targeted delivery of lacosamide-conjugated gold nanoparticles into the brain in temporal lobe epilepsy in rats
    (Elsevier, 2020) Yılmaz, Canan Uğur; Emik, Serkan; Orhan, Nurcan; Arican, Nadir; Küçük, Mutlu; N/A; N/A; N/A; Department of Chemistry; N/A; N/A; N/A; Temizyürek, Arzu; Atış, Müge; Akcan, Uğur; Khodadust, Rouhollah; Gürses, Rabia Candan; Ahıshalı, Bülent; Kaya, Mehmet; Other; PhD Student; PhD Student; Other; Faculty Member; Faculty Member; Faculty Member; Department of Chemistry;  Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; College of Sciences; School of Medicine; School of Medicine; School of Medicine; 357912; 346431; N/A; N/A; 110149; 9509; 10486
    Temporal lobe epilepsy (TLE) is the most common form of epilepsy with focal seizures, and currently available drugs may fail to provide a thorough treatment of the patients. The present study demonstrates the utility of glucose-coated gold nanoparticles (GNPs) as selective carriers of an antiepileptic drug, lacosamide (LCM), in developing a strategy to cross the blood-brain barrier to overcome drug resistance. Intravenous administration of LCM-loaded GNPs to epileptic animals yielded significantly higher nanoparticle levels in the hippocampus compared to the nanoparticle administration to intact animals. The amplitude and frequency of EEG-waves in both ictal and interictal stages decreased significantly after LCM-GNP administration to animals with TLE, while a decrease in the number of seizures was also observed though statistically insignificant. In these animals, malondialdehyde was unaffected, and glutathione levels were lower in the hippocampus compared to sham. Ultrastructurally, LCM-GNPs were observed in the brain parenchyma after intravenous injection to animals with TLE. We conclude that glucose-coated GNPs can be efficient in transferring effective doses of LCM into the brain enabling elimination of the need to administer high doses of the drug, and hence, may represent a new approach in the treatment of drug-resistant TLE.
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    Senile-onset subacute sclerosing panencephalitis, presenting with peculiar findings
    (Sage Publications Inc, 2019) Elmali, Ayse Deniz; Simsekoglu, Ruken; Sahin, Erdi; Ilki, Canan Duman; Uygun, Ozge; Coban, Oguzhan; N/A; Gürses, Rabia Candan; Faculty Member; School of Medicine; Koç University Hospital; 110149
    Subacute sclerosing panencephalitis (SSPE) is a well-known childhood disease; however, the adult onset of SSPE cases are also widely recognized where the oldest case reported is 52 years old. We report a 61-year-old woman patient presenting with atypical clinical and EEG features, diagnosed with SSPE. Measles and SSPE have decreased dramatically owing to worldwide immunization programs; however, there are still reasons to consider SSPE in differential diagnosis even in patients presenting with atypical clinical findings and older ages. First, there is a generation who missed the immunization era, constituting a latent disease pool. Second, antivaccination movements have led to a decline in MMR (measles, mumps, rubella) vaccination worldwide, leading to measles outbreaks and potential future SSPE cases. Third, most of the vaccination programs start measles immunization at the age of 12 months, leading to a shift in the incidence below the age of 1 year, when the risk of developing SSPE in adult life is higher. Finally, disruption in vaccination programs, in which fast disease transmission due to close contact living, unhygienic conditions of refugee camps, and limited access to health care in displaced populations have also led to measles outbreaks. In conclusion, we believe that neurologists for adults should consider SSPE in differential diagnosis, even in older patients with atypical presentations.
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    The effect of a seminar on medical students' information acquisition of and attitudes toward epilepsy
    (Academic Press Inc Elsevier Science, 2021) Yeni, Kubra; Tulek, Zeliha; Cavusoglu, Aysel; Bebek, Nerses; Baykan, Betul; Gokyigit, Aysen; N/A; Gürses, Rabia Candan; Faculty Member; School of Medicine; Koç University Hospital; 110149
    Aim: The aim of the present study was to investigate the effect of a brief seminar focusing on medical and social aspects of epilepsy on information acquisition of and attitudes toward epilepsy among medical school students. Method: The sample of this pretest-posttest study consisted of 57 fifth-grade medical students. The students participated in a one-hour seminar including medical and social aspects of epilepsy. An epilepsy-related awareness form developed by researchers and also the Epilepsy Attitude Scale were applied to the participants before and after the seminar. Results: It was determined that half of the students (50.9%) encountered an epileptic seizure and 12.3% of them applied first aid. The students had difficulty in describing the seizure type before education. Before education, the rate of describing the seizure was 47.4% for myoclonic seizure, 50.9% for simple partial seizure, and 64.9% for absence seizure, and after education, these rates increased to 82.5% (p < 0.001), 91.2% (p < 0.001), and 98.2% (p < 0.001), respectively. Students generally well described the seizure triggering factors; however, the rate of students reporting the menstrual period as triggering factors were lower (66.7%), and the rates increased after the education (93.0%) (p = 0.001). The percentages of correct answers increased also for the questions regarding seizure first aid. The percentage of students who felt competent for seizure first-aid management increased from 12.3% to 91.2% (p < 0.001) after the education. The correct response rates of students for social aspects of epilepsy was generally high. In our study, attitude toward epilepsy was also evaluated. After the education, a mild increase in the attitude score of students was found (p = 0.009). Although it is minimal, the number of students who marked more positive attitude increased for each item of the Attitude scale. Conclusion: Although a lack of acquaintance was found in some areas, awareness of epilepsy in our sample was at a moderate level. This study showed a positive effect of the education given to students on information acquisition and attitude. (C) 2020 Elsevier Inc. All rights reserved.