Araştırma Çıktıları | WoS | Scopus | TR-Dizin | PubMed
Permanent URI for this communityhttps://hdl.handle.net/20.500.14719/1741
Browse
30 results
Search Results
Publication Metadata only Temporal expression analysis of angiogenesis-related genes in brain development(2012) Ozkan, Abdulkadir; Biçer, Atilla; Avşar, Timuçin; Şeker, Aśkin N.; Toktaş, Zafer Orkun; Bozkurt, Süheyla Uyar; Baak, Ayse Nazli; Kilic, Turker D.; Ozkan, Abdulkadir, Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Department of Molecular Biology and Genetics, Boğaziçi Üniversitesi, Bebek, Turkey; Biçer, Atilla, Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey; Avşar, Timuçin, Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Dr. Orhan Cal Giray Molecular Biology, İstanbul Teknik Üniversitesi, Istanbul, Turkey; Şeker, Aśkin N., Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Department of Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Department of Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey; Bozkurt, Süheyla Uyar, Department of Neuropathology, Marmara Üniversitesi, Istanbul, Turkey; Baak, Ayse Nazli, Department of Molecular Biology and Genetics, Boğaziçi Üniversitesi, Bebek, Turkey; Kilic, Turker D., Prof. Dr. Peter Black Laboratory of Molecular Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Department of Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyBackground: The current knowledge on molecular pathogenesis of cerebral vascular malformations (CVM), which are believed to arise during development, is very limited. To unravel the molecular mechanisms involved in CVMs, a detailed understanding of the brain vascular development at molecular level is crucial. In this study, we aimed to explore the temporal and comparative expression profile of angiogenesis-related genes in the establishment of brain vasculature. Methods. Expression of a total of 113 angiogenesis-related genes during murine brain development has been analyzed using low-density array systems designed for angiogenesis-related genes. Bai1 (brain specific angiogenesis inhibitor-1), a recently identified novel anti-angiogenic gene, has been selected for further characterization. Results: We found that 62 out of 113 analyzed genes have expression in brain development at varying levels. Nineteen of these were differentially expressed between embryonic and postnatal stages (>1.5 fold). Bai1 is strongly expressed on growing blood vessels of cerebral cortex and hippocampus, partially expressed in the lateral regions of striatum, but mostly absent on the thalamus. Conclusion: By showing the comparative expression analysis of angiogenesis-related genes throughout brain development, the data presented here will be a crucial addition to further functional studies on cerebrovascular research. © 2012 zkan et al., licensee BioMed Central Ltd. © 2013 Elsevier B.V., All rights reserved.Publication Metadata only Total spondylectomy of an L3 osteosarcoma, L3 osteosarkomuna total spondilektomi cerrahisi(2013) Yilmaz, Baran; Ekşi̇, Murat Şakir; Toktaş, Zafer Orkun; Konya, Deniz; Yilmaz, Baran, Bahçeşehir Üniversitesi, Istanbul, Turkey; Ekşi̇, Murat Şakir, Department of Orthopedic Surgery-Spine Center, University of California, San Francisco, San Francisco, United States; Toktaş, Zafer Orkun, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Bahçeşehir Üniversitesi, Istanbul, TurkeyPrimary osteosarcoma is a rare malignant osseous tumor of vertebra. Prognosis has been improved with new technologies and surgical techniques. In modern era of spinal surgery en bloc resection has become more popular in these neoplasms. We presented a 19-year-old young man admitted to our clinic with low back pain. An L3 vertebral mass lesion was detected on MRI. CT-guided biopsy result was osteosarcoma. En bloc resection was planned. In the literature, intraoperative blood loss amounts were very high in osteosarcoma cases, so we decided to embolize the tumor pre-operatively. It worked in the surgery that only 700 ml of blood was lost. Although surgery was one staged (combined anterior and posterior approaches), it took 6 hours with 2 surgeons. Definitive diagnosis was osteosarcoma and the patient was referred to oncologists. Embolization should be kept in mind before vertebral tumor surgery to make it smooth and easy. © 2014 Elsevier B.V., All rights reserved.Publication Metadata only Rare solitary primary osseous lesions of the spine in adults, challenges in ct and mr imaging diagnosis with pathological correlation, Yetişkinlerde Nadir Primer Omurga Kemik Kökenli Lezyonları, CT ve MR ile Tanısal Görüntülemenin Patolojik Korelasyonundaki Zorluklar(Ege University Press Bornova Izmir 35100, 2015) Toktaş, Zafer Orkun; Yilmaz, Baran; Akakin, Akin In; Demir, Mustafa Kemal; Kurtkaya-Yapicier, Özlem Sahan; Onat, Elif; Urgun, Kamran; Konya, Deniz; Toktaş, Zafer Orkun, Bahçeşehir Üniversitesi, Istanbul, Turkey; Yilmaz, Baran, Bahçeşehir Üniversitesi, Istanbul, Turkey; Akakin, Akin In, Bahçeşehir Üniversitesi, Istanbul, Turkey; Demir, Mustafa Kemal, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kurtkaya-Yapicier, Özlem Sahan, Bahçeşehir Üniversitesi, Istanbul, Turkey; Onat, Elif, Bahçeşehir Üniversitesi, Istanbul, Turkey; Urgun, Kamran, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Bahçeşehir Üniversitesi, Istanbul, TurkeyThis pictorial essay is a review of the computerized tomography and magnetic resonance imaging of a few solitary primary osseous lesions encountered in the adults. The lesions discussed include giant cell tumor, Langerhans cell histiocytosis, Paget'sdisease, plasmacytoma, fibrous dysplasia and osteoblastoma. Challenges in computerized tomography and magnetic resonance imaging diagnosis of these lesions are mentioned with clinicoradiological differential diagnosis, and include pathological correlation. Although active diagnosis and radiological familiarity of these lesions is crucial for preventing unnecessary examinations or procedures, pathological evaluation is mandatory to establish final diagnosis. © 2015 Elsevier B.V., All rights reserved.Publication Open Access Cervical myelopathy due to single level disc herniation presenting as intramedullary mass lesion: What to do first?(Wolters Kluwer Medknow Publications, 2015) Ekşi̇, Murat Şakir; Özcan-Ekşi̇, Emel Ece; Yılmaz, Baran; Toktaş, Zafer Orkun; Konya, Deniz; Ekşi̇, Murat Şakir, Department of Orthopedic Surgery-Spine Center, UCSF Medical Center, San Francisco, United States; Özcan-Ekşi̇, Emel Ece, Department of Orthopedic Surgery-Spine Center, UCSF Medical Center, San Francisco, United States; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyCervical myelopathy (CM) is mostly a degenerative process ending in myelopathic and/or radiculopathic syndromes. On T2-weighted magnetic resonance imaging (MRI), CM appears as a hyperintense area near the spondylotic spine. This high intensity signal depends on the impact of outer forces and their duration. It also determines the prognosis of the surgical candidate. A 40-year-old male patient admitted to our clinic with right upper extremity weakness and hypoesthesia that had started 2 months earlier. On neurological examination there was 2/5 motor weakness of right biceps brachii, and hypoesthesia over right C6 dermatome. Right upper extremity deep tendon reflexes were hypoactive, but lower ones were hyperactive. After clinical and radiological work-up, preliminary diagnosis was directed to a spinal intramedullary tumor. Total resection of the herniated cervical disc fragment and the mass lesion was managed. Pathology of the mass lesion was compatible with subacute infarct tissue and inflammatory response. Final diagnosis was CM under effect of cervical disc herniation. Contrast-enhanced spinal cord myelopathic lesions are very rare and resemble much more tumors and inflammatory processes. However, the principal treatment approach totally differs depending on pathology. When there are both a disc herniation and a high clinical suspicion, biopsy should be delayed. The most probable solution will be surgery for the disc disease with thorough preoperative scanning of vascular malformations, clinical and radiological close follow-up after surgery. Biopsy or surgical resection can be performed if patient deteriorates despite the primary surgery. © 2021 Elsevier B.V., All rights reserved.Publication Metadata only Kyphectomy and Pedicular Screw Fixation with Posterior-Only Approach in Pediatric Patients with Myelomeningocele(S. Karger AG, 2015) Kaplan, Sümeyye Çoruh; Ekşi̇, Murat Şakir; Bayri, Yasar; Toktaş, Zafer Orkun; Konya, Deniz; Kaplan, Sümeyye Çoruh, Department of Neurosurgery, Bismil Devlet Hastanesi, Diyarbakir, Turkey; Ekşi̇, Murat Şakir, UCSF School of Medicine, San Francisco, United States; Bayri, Yasar, Department of Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyPurpose: Defective posterior spinal arch and paraspinal musculature lead to progressive kyphosis in patients with myelomeningocele. Kyphosis decreases the patients' functional status and quality of life. To correct or prevent further deterioration, different surgical techniques have been introduced. Our aim is to present our clinical experience in kyphectomy and pedicle screw fixation with a posterior-only approach in pediatric patients with myelomeningocele and to discuss the technique with a review of the literature. Materials and Methods: Four patients with lumbar and 2 patients with thoracolumbar kyphosis (female:male ratio = 1:5) secondary to myelomeningocele were operated between January 2009 and October 2012. The median age was 5.5 years (range = 3-10 years). The criteria of the patient selection for the procedure were progression of kyphosis angle, impaired truncal balance and cosmetic deformity. In this retrospective study, we performed chart reviews for demographic and clinical data. We measured the pre- and postoperative kyphosis angles by using the Cobb method on lateral x-rays. Results: The mean preoperative kyphosis angle was 114.3° (range = 91-136°). The mean operative time was 171.7 min (range = 110-220 min). The mean intraoperative blood loss was 450 cc (range = 300-700 cc). The postoperative mean kyphosis angle was 28.2° (range = 13-33°). Five patients had skin breakdown. After osteofusion was established, those 5 patients' instrumentations were explanted. No acute or immediate postoperative complications occurred. Other complications were pneumonia and urinary tract infection. In the long term, 2 patients died due to pneumonia and slit-ventricle syndrome, respectively. Conclusions: Kyphectomy and pedicle screw instrumentation with the posterior-only approach dramatically reduces the kyphosis angle that develops in patients with myelomeningocele. The method itself is less time-consuming and leads to less intraoperative blood loss compared to other methods used for this patient population. Skin breakdown is the most common short-term complication. © 2016 Elsevier B.V., All rights reserved.Publication Metadata only Association of collagen I, IX and vitamin D receptor gene polymorphisms with radiological severity of intervertebral disc degeneration in Southern European Ancestor(Springer Verlag service@springer.de, 2015) Toktaş, Zafer Orkun; Ekşi̇, Murat Şakir; Yilmaz, Baran; Demir, Mustafa Kemal; Özgen, Serdar; Kilic, Turker D.; Konya, Deniz; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Ekşi̇, Murat Şakir, UCSF School of Medicine, San Francisco, United States; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Demir, Mustafa Kemal, Department of Radiology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Özgen, Serdar, Department of Neurosurgery, Acıbadem Mehmet Ali Aydınlar Üniversitesi, Istanbul, Turkey; Kilic, Turker D., Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyPurpose: Several genomic loci have been previously found to be associated with intervertebral disc degeneration, so far. Data are mostly derived from northern European countries whereas data derived from Southern European Ancestor are limited. This study aimed to evaluate the association between radiological disease severity of lumbar disc degeneration and certain genetic loci in a sample of participants from Southern Europe. Methods: Seventy-five patients with mild to severe lumbar disc degeneration and 25 healthy controls were enrolled into the study. In each subject, each lumbar intervertebral disc was separately examined to obtain a total radiological score for disease severity. In addition, single-nucleotide polymorphisms of predefined genetic samples were analyzed in all participants: COL1A1 Sp1, COL9a2 Trp2, COL9a3 Trp3, and VDR TaqI. Results: Degeneration scores were significantly worse in cases with COL1A1 Sp1, COL9a3 Trp3, and VDR TaqI mutations, however, COL9a2 Trp2 mutation was not associated with a difference in the severity of disc degeneration. In addition, subjects with mutation in more than one gene sample (n = 20) had significantly worse degeneration scores than the remaining study participants (n = 80) (17.70 ± 2.72 vs. 21.81 ± 1.81, p < 0.001). Conclusion: Single-nucleotide polymorphisms occurring in COL1A1, COL9a3 and VDR genes seem to be associated with the development of lumbar disc degeneration in this cohort, possibly with even more pronounced association when multiple mutations are present in the same individual. By further prospective twin studies in associated genes and analyses of their relationship with environmental factors in an internationally sampled large cohort will make a more clear-minded conclusion about their association with disc degeneration, which would yield better appreciation and clinical planning of some predisposed people for these pathologies. © 2016 Elsevier B.V., All rights reserved.Publication Open Access Multiple hemorrhages in brain after spine surgery supra- and infra-tentorial components together(Wolters Kluwer Medknow Publications, 2015) Yılmaz, Baran; Işık, Semra; Ekşi̇, Murat Şakir; Özcan-Ekşi̇, Emel Ece; Akakın, Akın; Toktaş, Zafer Orkun; Konya, Deniz; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Işik, Semra, Department of Neurosurgery, T. C. Sağlık Bakanlığı Hakkari Devlet Hastanesi, Hakkari, Turkey; Ekşi̇, Murat Şakir, University of California, San Francisco, San Francisco, United States; Özcan-Ekşi̇, Emel Ece, University of California, San Francisco, San Francisco, United States; Akakin, Akin In, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyRemote cerebellar hemorrhage after cranial and spinal surgeries is a well-documented entity, so far concomitant supra- and infra-tentorial hemorrhage after spine surgery has rarely been reported in the literature. A 57-year-old woman presented with intractable low back pain and severely impaired mobility. One year ago, she underwent lumbar laminectomy and fusion with posterior spinal instrumentation between L2 and S1. She developed adjacent segment disease at the upper level of the instrumented vertebra. She had a revision surgery and underwent posterior laminectomy and fusion with bilateral transpedicular instrumentation between T10 and S1. She had severe headache, somnolence, and left hemiparesia 48 h after the surgery. Her emergent head computed tomography depicted intra-parenchymal hemorrhage in the right parietal lobe accompanying with subarachnoid hemorrhage, bilateral symmetrical cerebellar hemorrhages and pneumocephalus. She was treated nonsurgically and she got better despite some residual deficits. Symptoms including constant headache, nausea, vomiting, impaired consciousness, new onset seizure, and focal neurological deficit after spine surgeries should raise suspicion for intracranial intra-parenchymal hemorrhage. © 2021 Elsevier B.V., All rights reserved.Publication Open Access Tetraventricular central neurocytoma: A rare presentation with imaging-pathologic correlation(Medknow Publications B9, Kanara Business Centre, off Link Road, Ghatkopar (E) Mumbai 400 075, 2015) Akakın, Akın; Yılmaz, Baran; Demir, Mustafa Kemal; Kurtkaya-Yapıcıer, Özlem Sahan; Toktaş, Zafer Orkun; Kılıç, Türker; Akakin, Akin In, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Demir, Mustafa Kemal, Department of Radiology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kurtkaya-Yapicier, Özlem Sahan, Department of Pathology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kilic, Turker D., Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyCentral neurocytoma (CN) is a benign intraventricular neuronal tumor with a favorable prognosis. It accounts approximately 0.25-0.5% of intracranial tumors. In this report, we describe a very rare case of tetraventricular CN with imaging-pathologic correlation, and discuss their atypical features in a location together with treatment options. A 27-year-old man was admitted to the hospital with symptoms of progressive headaches of several months' duration. Magnetic resonance imaging of the brain revealed a well-circumscribed, lobulated intraventricular mass with numerous intratumoral cystlike areas. The mass was located in the enlarged lateral ventricles bilaterally extending to the third and the fourth ventricle. Surgical removal of the 4th ventricle component of the tumor was performed. Histomorphological and immunohistochemical findings of the tumor were consistent with CN. After pathological diagnosis, gamma knife surgery was performed. CN may present with atypical features in a location with a usual histopathological findings. To our knowledge, we described the third case of tetraventricular CN, which was partially treated with both surgical resection and radiosurgery. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only Gamma Knife treatment of low-grade gliomas in children(Springer Verlag service@springer.de, 2015) Ekşi̇, Murat Şakir; Yilmaz, Baran; Akakin, Akin In; Toktaş, Zafer Orkun; Kaur, Ahmet Cemil; Demir, Mustafa Kemal; Kilic, Turker D.; Ekşi̇, Murat Şakir, University of California, San Francisco, San Francisco, United States; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Akakin, Akin In, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kaur, Ahmet Cemil, Department of Pathology, Medical Park Göztepe Hospital, Istanbul, Turkey; Demir, Mustafa Kemal, Department of Radiology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kilic, Turker D., Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyBackground: Low-grade gliomas have good overall survival rates in pediatric patients compared to adults. There are some case series that reported the effectiveness and safety of Gamma Knife radiosurgery, yet they are limited in number of patients. We aimed to review the relevant literature for pediatric low-grade glial tumors treated with stereotactic radiosurgery, specifically Gamma Knife radiosurgery, and to present an exemplary case. Case description: A 6-year-old boy was admitted to clinic due to head trauma. He was alert, cooperative, and had no obvious motor or sensorial deficit. A head CT scan depicted a hypodense zone at the right caudate nucleus. The brain magnetic resonance imaging (MRI) depicted a mass lesion at the same location. A stereotactic biopsy was performed. Histopathological diagnosis was low-grade astrocytoma (grade II, World Health Organization (WHO) classification, 2007). Gamma Knife radiosurgery was applied to the tumor bed. Tumor volume was 21.85 cm3. Fourteen gray was given to 50 % isodose segment of the lesion (maximal dose of 28 Gy). The tumor has disappeared totally in 4 months, and the patient was tumor-free 21 months after the initial treatment. Discussion and conclusion: The presented literature review represents mostly single-center experiences with different patient and treatment characteristics. Accordingly, a mean/median margin dose of 11.3–15 Gy with Gamma Knife radiosurgery (GKRS) is successful in treatment of pediatric and adult low-grade glial tumor patients. However, prospective studies with a large cohort of pediatric patients should be conducted to make a more comprehensive conclusion for effectiveness and safety of GKRS in pediatric low-grade glial tumors. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only Lumbar Spinal Immature Ganglioneuroma with Conus Medullaris Invasion: Case Report(S. Karger AG, 2015) Yilmaz, Baran; Toktaş, Zafer Orkun; Akakln, Akln; Demir, Mustafa Kemal; Kurtkaya-Yapicier, Özlem Sahan; Konya, Deniz; Yilmaz, Baran, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Akakln, Akln, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Demir, Mustafa Kemal, Department of Radiology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kurtkaya-Yapicier, Özlem Sahan, Department of Pathology, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyGanglioneuroma (GN) is a benign rare tumor that originates from neural crest cells. It shares a common histogenic family with ganglioneuroblastoma and neuroblastoma and represents the most benign and differentiated form of the group. The most common locations of the GNs are the mediastinum and retroperitoneum. We report an extremely rare case of lumbar spinal GN with conus medullaris invasion and extradural paraspinal extension. A 10-year-old girl presented with a history of worsening lower-back pain and an intermittent tingling sensation in the left leg. Neurological examination revealed reduced sensation in the left L2-L5 dermatomes. Magnetic resonance imaging revealed an intra- and extradural mass extending from the D11 to L5 vertebral body level. There was conus medullaris invasion by the tumor. After L1-L5 laminotomies, the patient underwent tumor resection. Histopathological diagnosis was immature GN. GNs occurring within the spinal column are rare and may grow to a large size. Despite the size and the common involvement of both intra- and extraspinal compartments, the prognosis is usually excellent after complete excision using microsurgical techniques. © 2016 Elsevier B.V., All rights reserved.
- «
- 1 (current)
- 2
- 3
- »