Person: BEKAR, AHMET
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BEKAR
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AHMET
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Publication NEAT1 Is a novel oncogenic LncRNA and correlated with miR-143 in pediatric oligodendrogliomas(Karger, 2021-03-19) Ak Aksoy, Seçil; Mutlu, Melis; Balçin, Rabia Nur; Taşkapılıoğlu, Mevlut Özgür; Tekin, Çağla; Kaya, Seçkin; Civan, Muhammet Nafi; Kocaeli, Hasan; Bekar, Ahmet; Eser Ocak, Pınar; Çeçener, Gülşah; Egeli, Ünal; Tolunay, Şahsine; Tunca, Berrin; Ak Aksoy, Seçil; Mutlu, Melis; BALÇIN, RABİA NUR; TAŞKAPILIOĞLU, MEVLÜT ÖZGÜR; Tekin, Çağla; KAYA, İSMAİL SEÇKİN; Civan, Muhammet Nafi; KOCAELİ, HASAN; BEKAR, AHMET; Eser Ocak, Pınar; ÇEÇENER, GÜLŞAH; EGELİ, ÜNAL; TOLUNAY, ŞAHSİNE; TUNCA, BERRİN; Tıp Fakültesi; Beyin Cerrahisi Ana Bilim Dalı; 0000-0001-5472-9065; 0000-0002-4256-2250; 0000-0003-0132-9927; 0000-0002-3820-424X; 0000-0001-7904-883X; 0000-0002-1619-6680; ADM-8457-2022; FPB-0403-2022; GXV-3107-2022; AAW-5254-2020; GDC-6329-2022; JGS-1849-2023; HKP-0793-2023; FDK-3229-2022; CGB-7869-2022; AAI-2073-2021; AAP-9988-2020; AAH-1420-2021; AAI-1612-2021; ABI-6078-2020Introduction: The noncoding RNAs (ncRNAs) play a role in biological processes of various cancers including gliomas. The majority of these transcripts are uniquely expressed in differentiated tissues or specific glioma types. Pediatric oligodendroglioma (POG) is a rare subtype of diffuse glioma and accounts for <1% of pediatric brain tumors. Because histologically POG resembles adult OG, the same treatment is applied as adults. However, the significance in predicting outcomes in POG patients is unclear. In this study, we aimed to investigate the prognostic significance of expression -profiles of microRNA (miRNA) and long noncoding RNA -(LncRNA) in POGs. Methods: We investigated the levels of 13 known miRNAs and 6 LncRNAs in tumor samples from 9 patients with primary POG by using RT-PCR and analyzed their association with outcomes. Results: The expression levels of miR-21, miR-106a, miR-10b, and LncRNA NEAT1 were higher, and the expression level of miR-143 was lower in POG tissues compared with normal brain tissues (p = 0.006, p = 0.032, p = 0.034, p = 0.002, and p = 0.001, respectively). High levels of NEAT1 and low expression of miR-143 were associated with decreased probability of short disease-free survival (p = 0.018 and p = 0.022, respectively). Discussion: NEAT1 and miR-143 levels could serve as reciprocal prognostic predictors of disease progression in patients with POG. New treatment models to regulate the expression levels of NEAT1 and miR-143 will bring a new approach to the therapy of POG.Publication The immunohistochemical expression of c-met is an independent predictor of survival in patients with glioblastoma multiforme(Springer International Publishing Ag, 2014-02-01) Ölmez, O. F.; Çubukçu, E.; ÇUBUKÇU, ERDEM; Evrensel, T.; EVRENSEL, TÜRKKAN; Kurt, M.; Avcı, N.; Tolunay, S.; TOLUNAY, ŞAHSİNE; Bekar, Ahmet; BEKAR, AHMET; Deligönül, Adem; DELİGÖNÜL, ADEM; Hartavi, M.; Alkış, N.; Manavoğlu, O.; Tıp Fakültesi; Onkoloji Ana Bilim Dalı; ABX-9081-2022; AAJ-1027-2021; AAA-3961-2020; AAI-1612-2021Because the outcome of glioblastoma multiforme (GBM) remains dismal, there is an urgent need for a better molecular characterization of this malignancy. The aim of this prospective study was to investigate the prognostic impact of the expression of c-mesenchymal-epithelial transition (c-Met) a receptor tyrosine kinase implicated in expression growth, survival, motility/migration, and invasion in GMB patients managed according to the established diagnostic and therapeutic protocols.Between May 2003 and March 2011, a total of 69 patients (33 males and 36 females; mean age: 52.2 +/- A 12.9 years, age range: 23-81 years) referred to our Department for the surgical removal of GBM were evaluated immunohistochemically for c-Met expression. Progression-free survival (PFS) and overall survival (OS) served as the main outcome measures.Compared with c-Met- subjects (n = 38), c-Met+ subjects (n = 31) had both a significantly lower OS (15.3 +/- A 2.3 vs. 22.6 +/- A 2.5 months, respectively, p < 0.01) and PFS (12.3 +/- A 2.1 vs. 19.1 +/- A 2.6 months, respectively, p < 0.05). After allowance for potential confounders, multivariate Cox regression analysis identified c-Met+ as an independent predictor of both OS (hazard ratio = 1.7; 95 % confidence interval = 1.2-1.9, p < 0.01) and PFS (hazard ratio = 1.6; 95 % confidence interval = 1.1-2.3, p < 0.05).Our findings suggest that c-Met immunohistochemical expression is an independent predictor of outcomes in patients with GBM treated by standard of care.Publication Diabetes mellitus-mediated MALAT1 expression induces glioblastoma aggressiveness(Turkish Neurosurgical Soc, 2023-01-01) Kocaeli, Aysen Akkurt; Aksoy, Seçil A. K.; Erçelik, Melis; Tezcan, Gülçin; Tekin, Çağla; Kocaeli, Hasan; Bekar, Ahmet; Taşkapılıoğlu, Mevlüt Özgür; Tolunay, Şahsine; Tunca, Berrin; AKSOY, SEÇİL; Erçelik, Melis; TEZCAN, GÜLÇİN; Tekin, Çağla; KOCAELİ, HASAN; BEKAR, AHMET; TAŞKAPILIOĞLU, MEVLÜT ÖZGÜR; TOLUNAY, ŞAHSİNE; TUNCA, BERRİN; Tıp Fakültesi; Tıbbi Biyoloji Ana Bilim Dalı; 0000-0002-3760-9755; ADM-8457-2022; EUG-3329-2022; JJL-1176-2023; GDC-6329-2022; FDK-3229-2022; JWS-5881-2024; IRO-2619-2023; AAI-1612-2021; JXJ-7901-2024AIM: To describe the role of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in glioblastoma (GB) progression in patients concurrently diagnosed with diabetes mellitus (DM).MATERIAL and METHODS: Formalin-fixed paraffin-embedded (FFPE) tumor samples of 47 patients diagnosed with GB only and 13 patients diagnosed with GB and DM (GB-DM) were enrolled in this study. Data for p53 and Ki67 immunohistochemical staining of the tumors and blood HbA1c levels of patients with DM were retrospectively collected. MALAT1 expression was assessed using quantitative real-time polymerase chain reaction.RESULTS: The coexistence of GB and DM induced the nuclear expression of p53 and Ki67 compared with GB only. MALAT1 expression was higher in GB-DM tumors than in GB only tumors. The expression of MALAT1 and HbA1c levels were positively correlated. Additionally, MALAT1 was positively correlated with tumoral p53 and Ki67. The disease-free survival of patients with GB-DM with high MALAT1 expression was shorter than that of those diagnosed with GB only and with a lower MALAT1 expression.CONCLUSION: Our findings suggest that one of the mechanisms of the facilitating effect of DM on GB tumor aggressiveness is via MALAT1 expression.Publication Hemorrhagic presentation of previously silent brain tumors(Elsevier Espana Slu, 2023-07-03) Türkkan, Alper; Khezri, Marzieh Karimi; Eser, Pınar; Kuytu, Turgut; Tolunay, Şahsine; Bekar, Ahmet; TOLUNAY, ŞAHSİNE; BEKAR, AHMET; Eser, Pınar; Tıp Fakültesi; Patoloji Ana Bilim Dalı; 0000-0003-0132-9927; AAI-2073-2021; CGB-7869-2022; AAI-1612-2021Introduction and objectives: Acute presentation with intracranial hemorrhage owing to a previously silent brain tumor (BT) is rare. Although any BT can bleed, the frequency and type of bleeding varies across tumor types.Materials and methods: We aimed to retrospectively review our experience with 55 patients with BTs presenting with ICH.Results: Signs of increased intracranial pressure were the most common symptoms. The temporal lobe was the most common lesion site (n = 22). Hemorrhages were mainly confined to the tumor margins (HCTs) (n = 34). Extensive intraparenchymal hemorrhages (EIHs) were mainly associated with moderately/severely decreased levels of consciousness (LOCs) (n = 15/16). High-grade glioma (HGGT) (n = 25) was the leading pathological diagnosis followed by metastasis (MBT) (n = 16/55). The hemorrhage type was associated with the pathological diagnosis of the tumor. Patients with HGGT (n = 19/25) and MBT (n = 9/16) mainly presented with HCTs, whereas low-grade gliomas (LGGT) primarily caused EIHs (n = 6/7).Conclusions: Hemorrhagic presentation is a rare occurrence in BTs. Among all, MBT and HGGT are responsible for majority of the cases. Importantly, despite their relatively benig ncharacteristics, LGGTs mainly result in extensive parenchymal destruction once they bleed. Maximum surgical resection of hemorrhagic BTs and decompression of the affected brain regions followed by histological confirmation of the diagnosis should be the main goals of treatment in cases with hemorrhagic BTs.(c) 2022 Published by Elsevier Espana, S.L.U. on behalf of Sociedad Espanola deNeurocirug ' ia.Publication Co-loading of Temozolomide with Oleuropein or rutin into polylactic acid core-shell nanofiber webs inhibit glioblastoma cell by controlled release(Elsevier, 2023-09-03) Erçelik, Melis; Tekin, Çağla; Parin, Fatma Nur; Mutlu, Büşra; Doğan, Hazal Yılmaz; Tezcan, Gülçin; Aksoy, Seçil Ak; Gürbüz, Melisa; Yıldırım, Kenan; Bekar, Ahmet; Kocaeli, Hasan; Taşkapılıoğlu, Mevlüt Özgür; Eser, Pınar; Tunca, Berrin; Erçelik, Melis; Tekin, Çağla; TEZCAN, GÜLÇİN; Aksoy, Seçil Ak; Gürbüz, Melisa; BEKAR, AHMET; KOCAELİ, HASAN; TAŞKAPILIOĞLU, MEVLÜT ÖZGÜR; Eser, Pınar; TUNCA, BERRİN; Diş Hekimliği Fakültesi; Beyin Cerrahi Ana Bilim Dalı; 0000-0002-1640-6035; 0000-0003-0132-9927; 0000-0002-1619-6680; ABX-9081-2022; AAI-2073-2021; HKM-7750-2023; EUG-3329-2022; GDC-6329-2022; JJL-1176-2023; JJH-2235-2023; CGB-7869-2022; FDK-3229-2022; IRO-2619-2023Glioblastoma (GB) has susceptibility to post-surgical recurrence. Therefore, local treatment methods are required against recurrent GB cells in the post-surgical area. In this study, we developed a nanofiber-based local therapy against GB cells using Oleuropein (OL), and rutin and their combinations with Temozolomide (TMZ). The polylactic acid (PLA) coreshell nanofiber webs were encapsulated with OL (PLA(OL)), rutin (PLA(rutin)), and TMZ (PLA(TMZ)) by an electrospinning process. A SEM visualized the morphology and the total immersion method determined the release characteristics of PLA webs. Real-time cell tracking analysis for cell growth, dual Acridine Orange/Propidium Iodide staining for cell viability, a scratch wound healing assay for migration capacity, and a sphere formation assay for tumor spheroid aggressiveness were used. All polymeric nanofiber webs had core -shell structures with an average diameter between 133 +/- 30.7-139 +/- 20.5 nm. All PLA webs promoted apoptotic cell death, suppressed cell migration, and spheres growth (p < 0.0001). PLA(OL) and PLA(TMZ) suppressed GB cell viability with a controlled release that increased over 120 h, while PLA(rutin) caused rapid cell inhibition (p < 0.0001). Collectively, our findings suggest that core-shell nanowebs could be a novel and effective therapeutic tool for the controlled release of OL and TMZ against recurrent GB cells.Publication Nuances to provide ideas for radiologic diagnosis in primary spinal paragangliomas: Report of two cases(Taylor & Francis, 2019-03-04) Türkkan, Alper; Kuytu, Turgut; Yıldırım, Sükrü; Bekar, Ahmet; BEKAR, AHMET; Tıp Fakültesi; ABX-9081-2022Spinal paragangliomas are rarely-observed neuroendocrine benign tumors in the extra-adrenal paraganglionic system. Primary spinal involvement is even rarer. Radiologic differential diagnosis is not easy. This paper presents 2 lumbar paraganglioma cases and focuses on nuances to provide ideas for radiological differential diagnosis.Publication Olea europaea leaf phenolics oleuropein, hydroxytyrosol, tyrosol, and rutin Induce apoptosis and additionally affect temozolomide against glioblastoma: In particular, oleuropein inhibits spheroid growth by attenuating stem-like cell phenotype(Mdpi, 2023-02-01) Erçelik, Melis; Tekin, Çağla; Tezcan, Gülçin; Aksoy, Seçil Ak; Bekar, Ahmet; Kocaeli, Hasan; Taşkapılıoğlu, Mevlüt Özgür; Eser, Pınar; Tunca, Berrin; Erçelik, Melis; Tekin, Çağla; TEZCAN, GÜLÇİN; Aksoy, Seçil Ak; BEKAR, AHMET; KOCAELİ, HASAN; TAŞKAPILIOĞLU, MEVLÜT ÖZGÜR; Eser, Pınar; TUNCA, BERRİN; Tıp Fakültesi; Tıbbi Biyoloji Ana Bilim Dalı; 0000-0002-5956-8755; 0000-0001-5472-9065; 0000-0003-0132-9927; 0000-0002-1619-6680; EUG-3329-2022; GDC-6329-2022; AAH-3843-2020; ADM-8457-2022; CGB-7869-2022; FDK-3229-2022; AAW-5254-2020; AAI-2073-2021; ABI-6078-2020The effects of Olea europaea leaf extract (OLE) phenolics, including oleuropein (OL), hydroxytyrosol (HT), tyrosol (TYR), and rutin against glioblastoma (GB), independently and in combination with temozolomide (TMZ), were investigated in T98G and A172 cells. Cell growth was assessed by WST-1, real-time cell analysis, colony formation, and cell cycle distribution assays. A dual acridine orange propidium iodide (AO/PI) staining and annexin V assay determined cell viability. A sphere-forming assay, an intracellular oxidative stress assay, and the RNA expression of CD133 and OCT4 investigated the GB stem-like cell (GSC) phenotype. A scratch wound-healing assay evaluated migration capacity. OL was as effective as OLE in terms of apoptosis promotion (p < 0.001) and GSC inhibition (p < 0.001). HT inhibited cell viability, GSC phenotype, and migration rate (p < 0.001), but its anti-GB effect was less than the total effect of OLE alone. Rutin decreased reactive oxygen species production and inhibited colony formation and cell migration (p < 0.001). TYR demonstrated the least effect. The additive effects of OL, HT, TYR and rutin with TMZ were significant (p < 0.001). Our data suggest that OL may represent a novel therapeutic approach against GB cells, while HT and rutin show promise in increasing the efficacy of TMZ therapy.Publication A clinical evaluation of gelastic and dacrystic seizures: A multicenter study(Assoc Arquivos Neuro- Psiquiatria, 2022-12-01) Demir, Aylin Bican; Öz, Başak Yılmaz; Yıldız, Mustafa Onur; Türk, Bengi Gül; Tanrıverdi, Taner; Bekar, Ahmet; Yeni, Naz; Bora, İbrahim; BİCAN DEMİR, AYLİN; BEKAR, AHMET; BORA, İBRAHİM HAKKI; Tıp Fakültesi; Epilepsi Merkezi; Nöroloji Ana Bilim Dalı; 0000-0001-6739-8605; ENI-7759-2022; CGB-7869-2022; V-7170-2017Background Gelastic seizures are extremely rare, short-lasting, unprovoked, and uncontrollable laughing attacks. We conducted this retrospective evaluation to determine whether these symptoms, manifesting in different forms, such as cheerful laughter, laughing, smiling, and sobbing had any value in terms of etiology or localization.Methods A total of 31 patients who exhibited bouts of laughing or crying and who were under follow-up between 2000 and 2019 at tertiary epilepsy centers were included in the study. Laughing seizures were divided into three groups in terms of semiology (i.e., laughter with mirth, laughter without mirth, and smile). Dacrystic seizures were accompanied by some gelastic seizures and were divided into two groups in terms of semiology (i.e., weeping loudly [motor and voice-sobbing] and crying).Results Of the 27 patients with laughing seizures, 12 had seizures that manifested with smiling, 7 had seizures that manifested with laughing and mirth, and 8 had seizures that manifested with laughter without mirth. Dacrystic-gelastic seizures were observed in four patients, among whom 2 patients had crying and laughter without mirth and 2 patients had weeping loudly and laughter without mirth episodes.Conclusion Gelastic and dacrystic seizures often suggest hypothalamic hamartomas, in the literature. This rare ictal behavior can originate from different cortical locations and lesions of a different nature. However, we found that gelastic seizures with smiling were a more homogenous group with regard to location in the temporal lobe, which we aimed to show by evaluating the patients included in this study.Publication The survival effect of resection of cranial metastatic lesions in patients with lung cancer(Elsevier Science, 2015-09-01) Deligönül, Adem; Taşkapılıoğlu, Özgür; Melek, Hüseyin; Bekar, Ahmet; Çetinkaya, Gamze; Sarihan, Süreyya; Bayram, Ahmet Sami; Gebitekin, Cengiz; Evrensel, Türkkan; DELİGÖNÜL, ADEM; TAŞKAPILIOĞLU, MEVLÜT ÖZGÜR; MELEK, HÜSEYİN; BEKAR, AHMET; Çetinkaya, Gamze; SARIHAN, SÜREYYA; BAYRAM, AHMET SAMİ; GEBİTEKİN, CENGİZ; EVRENSEL, TÜRKKAN; Tıp Fakültesi; İç Hastalıkları Ana Bilim Dalı; Tıbbi Onkoloji Bilim Dalı; 0000-0001-5472-9065; 0000-0003-4816-5798; 0000-0003-0684-0900; AAI-5039-2021; ABX-9081-2022; AAH-4970-2021; AAE-1069-2022; JDW-2654-2023; AAJ-1027-2021; JCE-0097-2023; ABB-8161-2020; ABB-7580-2020Publication A rare cause of epilepsy: Ulegyria revisited in a series of 10 patients(Sage Publications, 2021-09-17) Demir, Aylin Bican; Eser, Pınar; Bekar, Ahmet; Hakyemez, Bahattin; Bora, İbrahim; BİCAN DEMİR, AYLİN; Eser, Pınar; BEKAR, AHMET; HAKYEMEZ, BAHATTİN; BORA, İBRAHİM HAKKI; Tıp Fakültesi; Nöroloji Ana Bilim Dalı; Epilepsi Merkezi; 0000-0001-6739-8605; 0000-0003-0132-9927; 0000-0002-3425-0740; ABX-9081-2022; AAI-2073-2021; V-7170-2017; AAI-2318-2021; ENI-7759-2022Introduction. Ulegyria results from perinatal hypoxic-ischemic brain injury in term infants. The specific mushroom-shaped configuration of ulegyria results from small atrophic circumvolutions at the bottom of a sulcus underlying an intact gyral apex. Clinically, ulegyria is generally associated with epilepsy. Here, we aimed to delineate the characteristics of patients with ulegyria and the epileptic seizures they experience. Material and methods. Medical records including radiology and pathology reports, video-electroencephalographic (EEG) analysis, operative notes, hospital progress and outpatient clinic notes were reviewed retrospectively in a total of 10 ulegyria patients. Results. Patients ages ranged between 24 and 58 years (mean, 32 +/- 9.8 years). Past medical history was confirmed for neonatal asphyxia in 2 (20%). Neurological examination was remarkable for spastic hemiparesis in 1 (10%) patient with perisylvian ulegyria and for visual field deficits in 2 patients (20%) with occipital ulegyria. Ulegyria most commonly involved the temporoparietal region (n = 5, 50%) followed by the perisylvian area (n = 2, 20%). Except the one with bilateral perisylvian ulegyria, all patients had unilateral lesions (n = 9, 90%). Hippocampal sclerosis accompanied ulegyria in 2 patients (20%). All patients experienced epileptic seizures. Mean age at seizure onset was 8.8 +/- 5.4 years (range, 2-20 years). Interictal scalp EEG and EEG-video monitoring records demonstrated temporoparietal and frontotemporal activities in 5 (50%) and 2 (20%) patients, respectively. The seizures were successfully controlled by antiepileptic medication in 8 patients (n = 8, 80%). The remaining 2 patients (%20) with concomitant hippocampal sclerosis required microsurgical resection of the seizure foci due to medically resistant seizures. Discussion. Ulegyria is easily recognized with its unique magnetic resonance imaging characteristics and clinical presentation in the majority of cases. It is highly associated with either medically resistant or medically controllable epileptic seizures. The treatment strategy depends on the age at onset and extends of the lesion that has a significant impact on the severity of the clinical picture.
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