Baran, O. | Kasimcan, O. | Sav, A. | Oruckaptan, H.

Article | 2019 | World Neurosurgery126 , pp.369 - 375

Background: Intramedullary glial neoplasms affecting the entire spinal cord from the cervicomedullary junction to conus medullaris are termed holocord tumors. Pilocytic astrocytomas are relatively uncommon tumors forming holocord involvement. Hitherto 24 holocord astrocytoma cases were reported in the literature. Here, a case of an adult holocord pilocytic astrocytoma was presented. Case Description: A 29-year-old female patient presented with a subtotal resection. Histopathologic examination revealed pilocytic astrocytoma, World Health Organization grade 1, presenting holocord involvement. Magnetic resonance imaging showed a mass c . . .ontaining necrotic and cystic foci leading to an expansion along the entire spinal cord extending from C4 to conus medullaris. Conclusions: Reported holocord pilocytic astrocytomas in the relevant literature cases were reviewed. When evaluating magnetic resonance imaging scans of adult patients with various neurologic symptoms, i.e., weakness and fecal and urinary incontinence, pilocytic astrocytoma should be considered among differential diagnoses of intramedullary mass lesions. © 2019 Elsevier Inc Daha fazlası Daha az

Mutlu, O. | Olcay, A.B. | Bilgin, C. | Hakyemez, B.

Article | 2019 | World Neurosurgery127 , pp.369 - 375

Background: Flow diverter stents are often used in the treatment of giant aneurysms at carotid arteries. Although these stents promise to decrease blood flow into the aneurysm sac, little is known about hemodynamics inside the aneurysm once the stent is planted into the aneurysm neck. To further explore this, computational fluid dynamics and Lagrangian coherent structure (LCS) techniques were used to evaluate the time evolution mechanism of stagnation regions inside an aneurysm. The purpose of this work is to provide a quantitative effectiveness comparison of 2 different flow diverter stents placed into the aneurysm neck based on th . . .eir stagnation zone formations in the sac. Methods: In numerical modeling, Womersley function, and fluidsolid interaction were defined as the 3 cardiac cycles for blood velocity and the aneurysm wall, respectively. Moreover, blood was accepted as a non-Newtonian fluid, and mean arterial blood pressure of the patient was entered into the computational domain to accurately mimic the hemodynamics inside the aneurysm sac accurately. Results: The numerical analyses revealed that the use of a Fred-type stent in the aneurysm neck causes fluid flow zone formations yielding to sequenced stagnated regions. Time evolution of stagnation regions in an aneurysm sac was shown just after a flow diverter stent was employed at a patient's aneurysm neck. Furthermore, the stagnation field in the Fred stent–fitted aneurysm was nearly 4.8 times the stagnation area of the Surpass brand stent–attached aneurysm. Conclusions: Finite time Lyapunov exponent fields obtained from the LCS techniques demonstrated a good agreement with the patient's digital subtraction angiography images obtained just after treatment. © 2019 Elsevier Inc Daha fazlası Daha az

Lafazanos, S. | Türe, U. | Harput, M.V. | Gonzalez Lopez, P. | Firat, Z. | Türe, H. | Yaşargil, M.G.

Review | 2015 | World Neurosurgery83 ( 5 ) , pp.836 - 841

Objective A challenging step of the paramedian supracerebellar-transtentorial approach is to expose the anterior portion of the mediobasal-temporal region (MTR), a step that seems most affected by the steepness of the tentorium. The objective of this study was to define magnetic resonance imaging measurements that can predict the level of challenge in exposing the anterior portion of the MTR. Methods Cranial magnetic resonance imaging studies of 100 healthy individuals were examined. The tentorial and occipital angles were measured, and the amount of brain tissue that remained hidden on the microscopic view in front of the petrous a . . .pex was indirectly estimated. These measurements were statistically compared with the cephalic index of each person. Results The mean values for the tentorial and occipital angles were 42° (range 25°-53°) and 98° (range 69°-122°), respectively. The results proved that the higher the tentorial angle, the higher the occipital angle and the greater the amount of hidden brain tissue. Of 100 persons, 3 (3%) were found to be dolichocephalic, 23 (23%) were mesocephalic, and 74 (74%) were brachycephalic. Statistical analysis proved that individuals with a dolichocephalic cranial shape have lower tentorial and occipital angles. Conclusions The results provide strong evidence proving that the lesser the tentorial and occipital angles, the easier the exposure of the anterior portion of the MTR during the paramedian supracerebellar-transtentorial approach. The tendency of the cranial shape toward dolichocephaly seems to have the same practical value in choosing the approach. It is easier to expose the anterior portion of the MTR in these individuals. © 2015 Elsevier Inc. All rights reserved Daha fazlası Daha az

Keser, N. | Kuskucu, A. | Is, M. | Celikoglu, E.

Article | 2019 | World Neurosurgery121 , pp.836 - 841

Background: The etiology of Chiari I malformation (CMI) has not been fully elucidated. Therefore, we performed a genetic study of a Turkish family in which 3 sisters had a diagnosis of CMI with or without syringomyelia. Methods: In a family with 7 children, 4 daughters complained of occipital headaches. In 2 of these daughters, CMI had been diagnosed during their 30s, and CMI plus syrinx had been diagnosed in the other daughter in her 40s. Cranial magnetic resonance imaging of the fourth daughter who had developed headaches during her 30s showed normal findings. Because the other siblings in the family were asymptomatic, radiologica . . .l examinations were not performed. The family had a history of distant consanguineous marriage between parents. Additionally, the father had died, and the mother was asymptomatic, with radiologically normal findings. Array comparative genome hybridization studies were performed for 12 persons from 3 generations of this family. Results: None of the 12 cases examined harbored copy number variations. Conclusions: This family with 3 sisters having CMI suggested a possible autosomal recessive single-gene etiology. Cases of familial CMI are unusual but important to study because they could reveal the specific genes involved in posterior fossa/foramen magnum structure and function and provide insights into the cause of sporadic cases. © 2018 Elsevier Inc Daha fazlası Daha az

Yaltırık, K. | Güdü, B.O. | Işık, Y. | Altunok, Ç. | Tipi, U. | Atalay, B.

Article | 2018 | World Neurosurgery116 , pp.836 - 841

Background: There is a strong relationship between lower back pain and paraspinal muscle atrophy. In this study, we aimed to investigate the prevalence of lumbar paravertebral muscle atrophy in patients with and without single-level disc herniation. Methods: The 110 retrospectively analyzed patients in this study were divided into 2 groups. Group A included 55 patients with radiologically confirmed single-level disc herniation with back pain and radiculopathy. Group B included 55 patients with back pain without radiologic lumbar disc herniation. The paravertebral muscle cross-sectional areas were measured in both groups by 2 indepen . . .dent observers. Results: In total, 68 women and 42 men were examined. Their mean age was 40.85 years old. The mean ages of groups A and B were 42.49 and 39.22 years, respectively. The cross-sectional areas of the multifidus muscles (MM) and erector spinae muscles were significantly greater in group B than in group A (P < 0.0001). However, there were no statistically significant differences in the psoas major cross-sectional areas, disc heights, and perpendicular distances between the MM and the laminae. Conclusions: The MM and erector spinae muscle groups are innervated by the dorsal root of the spinal nerve arising from the same level; therefore, long-term pressure on the root caused by disc herniation can cause atrophy and degeneration of that muscle group. © 2018 Elsevier Inc Daha fazlası Daha az

Kalayci, M. | Kocdor, M.A. | Kuloglu, T. | Sahin, İ. | Sarac, M. | Aksoy, A. | Aydin, S.

Article | 2017 | Life Sciences186 , pp.102 - 110

Aims The purpose of our investigative work has been to determine whether there can be therapeutic roles in the administration of sildenafil citrate, heparin and several neuropeptides on an animal model where gastric ulcers were induced with acetic acid, and to compare their efficacy. Materials and methods The animals were divided into 13 groups, with 4 animals in each. Gastric ulcers was induced in the animals of 12 groups with one untreated group being left as the control (Group I - control; given normal saline (NS)). The other groups were: Group II (ulcer + NS); Group III (5 mg/kg sildenafil citrate, low dose); Group IV (10 mg/kg . . .sildenafil citrate, high dose); Group V (0.6 mg/kg heparin, low dose); Group VI (6 mg/kg heparin, high dose); Group VII (20 nmol/kg des-acyl ghrelin); Group VIII (40 nmol/kg des-acyl ghrelin); Group IX (4 nmol/kg acyl ghrelin); Group X (8 nmol/kg acly ghrelin); Group XI (20 pmol/kg Nesfatin-1); Group XII (15 nmol/kg Obestatin) and Group XIII (5 nmol/kg Neuropeptide Y). Gastric neuropeptide expression was measured using an immunohistochemical method, and the amount in circulation was detected using ELISA. To compare with no treatment, the controls and other treatment groups, we recorded loss of the surface epithelium of the stomach, erosion, bleeding and inflammatory cell infiltration in the upper halves of the gastric glands. Key findings The muscularis and the layers beneath it were, however, apparently normal. The gastric mucosa healed with little or no inflammation when sildenafil citrate, low dose heparin, ghrelin, NUCB2/Nesfatin-1, obestatin, Neuropeptide Y were administered. Significance Overall the data indicate that low dose heparin, and especially sildenafil citrate and neuropeptides, can be used clinically as an alternative approach in the treatment of the gastric ulcer. © 2017 Elsevier Inc Daha fazlası Daha az

Imamoglu, S. | Kaya, V. | Oral, D. | Perente, I. | Basarir, B. | Yilmaz, O.F.

Article | 2014 | Journal of Cataract and Refractive Surgery40 ( 5 ) , pp.785 - 792

Purpose To assess the efficacy and safety of corneal wavefront-guided custom laser in situ keratomileusis (LASIK) to correct refractive errors and higher-order aberrations (HOAs) after penetrating keratoplasty (PKP). Setting Beyoglu Eye Training and Research Hospital, Istanbul, Turkey. Design Noncomparative case series. Methods The study comprised consecutive patients who were unable to tolerate spectacles or contact lenses for the correction of anisometropia after PKP and had corneal wavefront-guided custom LASIK. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction spherical equivalent (MRSE), . . .and corneal HOAs were recorded before and after LASIK. Results The study evaluated 11 eyes (10 patients). The mean follow-up after LASIK was 24.3 months ± 11.7 (SD) (range 9 to 36 months). The mean MRSE was -2.97 ± 1.66 diopters (D) (range -0.50 to -5.38 D) preoperatively and -0.88 ± 0.96 D (range -2.75 to 0.5 D) postoperatively. The mean total higher-order root mean square (RMS) was 4.65 ± 1.14 µm (range 2.26 to 5.94 µm) preoperatively and 2.71 ± 1.31 µm (range 1.22 to 5.33 µm) postoperatively. Postoperatively, the UDVA improved in 7 eyes and remained unchanged in 4 eyes. The CDVA improved in all eyes postoperatively even cases in which the attempted astigmatic correction was not totally achieved. Conclusions Corneal wavefront-guided custom LASIK after PKP did not totally correct both refractive errors and HOAs because of the high volume of laser ablation required and inadequate corneal stromal thickness. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned. © 2014 ASCRS and ESCRS Daha fazlası Daha az

Karaca, F. | Öner, M.A.

Article | 2015 | Technological Forecasting and Social Change91 , pp.327 - 340

https://hdl.handle.net/20.500.11831/744

Saritas, O. | Oner, M.A.

Article | 2004 | Technological Forecasting and Social Change71 ( 01.02.2020 ) , pp.27 - 65

This paper proposes a new systems approach to foresight studies. The paper will first indicate the complex and conflicting nature of long-term decision-making process. Then, the need for systems approach will be highlighted by the analysis of 1995 UK Delphi survey results and the scenarios of 2000 UK foresight scenarios. The paper proposes two methodologies, namely Integrated Management Model (IMM) and Roadmapping, in order to overcome challenges introduced by the multidimensional characteristics and complex nature of foresight studies. Based on systemic approach, IMM offers a useful way of developing long-term normative policies an . . .d strategies and their transformations into actions by considering necessary changes in organizational structures and behaviors. In addition, roadmapping is used to capture, manipulate and manage information to decrease complexity in the foresight by constructing roadmaps. In the paper, IMM and roadmapping are employed first to analyze UK foresight results and then to develop a new methodology to formulate Delphi events and scenarios for the successful implementation of foresight. This paper also promotes the integrated use of foresight techniques such as scenarios and Delphi rather than one for another. © 2003 Elsevier Inc. All rights reserved Daha fazlası Daha az

Tuysuz, E.C. | Gulluoglu, S. | Yaltirik, C.K. | Ozbey, U. | Kuskucu, A. | Çoban, E.A. | Bayrak, O.F.

Article | 2019 | Experimental Cell Research380 ( 1 ) , pp.9 - 19

Chordoma is a rare, slow-growing tumor thought to arise from remnants of embryonic notochord associated with an aggressive outcome. Cancer stem-like cells (CSCs)are related to tumorigenesis, recurrence, and resistance in cancers. Therefore, chordoma CSCs are possible targets for chordoma treatment. In this study, dysregulated miRNAs were determined in chordoma CSCs and identified their role in chordoma. Dysregulated miRNAs were determined via miRNA microarray and validated through qPCR. miRNAs were transiently transfected to the chordoma cell lines and their roles in proliferation, apoptosis, migration and invasion capacities and st . . .em-like properties were identified. Finally, a relationship between clinicopathological features and dysregulated miRNAs has been evaluated among 21 chordoma patients. CD133 + CD15 + cells exhibited CSC phenotype with increased CSC- and Epithelial-Mesenchymal Transition (EMT)-related gene expression, invasion, migration, tumorosphere- and colony-forming abilities. In addition, WNT5A, TGF-?, BTG2 and MYCBP genes involved in CSC-related pathways, were targets of miR-140-3p, miR-148a-3p, miR-210-5p and miR-574-5p, respectively. Transfection of CSC-related miRNAs also increased migration and invasion along with stem cell phenotype. Finally, we determined that miR-140-3p and miR-148a-3p expressions correlated with Ki67 while miR-140-3p and TGF-? expressions were correlated with p53. Moreover, MYCBP expression was positively correlated with tumor volume, and metastasis was associated with the expression of miR-210-5p and TGF-? in our patient cohort. Through these findings, we conclude that chordoma CSCs have distinctive miRNA profile, which can regulate stem-like properties of chordoma CSCs. © 2019 Elsevier Inc Daha fazlası Daha az

Serra, C. | Türe, U. | Krayenbühl, N. | Şengül, G. | Yaşargil, D.C.H. | Yaşargil, M.G.

Article | 2017 | World Neurosurgery97 , pp.438 - 452

Objective To describe the topographic anatomy of surgically accessible surfaces of the human thalamus as a guide to surgical exploration of this sensitive area. Methods Using the operating microscope, we applied the fiber microdissection technique to study 10 brain specimens. Step-by-step dissections in superior-inferior, medial-lateral, and posterior-anterior directions were conducted to expose the surfaces and nuclei of the thalamus and to investigate the relevant anatomic relationships and visible connections. Results There were 4 distinct free surfaces of the thalamus identified: lateral ventricle surface, velar surface, cistern . . .al surface, and third ventricle surface. Each is described with reference to recognizable anatomic landmarks and to the underlying thalamic nuclei. The neural structures most commonly encountered during the surgical approach to each individual surface are highlighted and described. Conclusions Observations from this study supplement current knowledge, advancing the capabilities to define the exact topographic location of thalamic lesions. This improved understanding of anatomy is valuable when designing the most appropriate and least traumatic surgical approach to thalamic lesions. These proposed surface divisions, based on recognizable anatomic landmarks, can provide more reliable surgical orientation. © 2016 Elsevier Inc Daha fazlası Daha az

Utine, C.A. | Tzu, J.H. | Akpek, E.K.

Article | 2011 | American Journal of Ophthalmology151 ( 1 ) , pp.170 - 1740

Purpose To report the clinical outcomes of lamellar keratoplasty using sterile, gamma-irradiated corneal tissues (VisionGraft) for partial-thickness corneal defects. Design Interventional case series. Methods The medical records of 10 patients with partial-thickness corneal defects who were operated at The Wilmer Eye Institute between April 2009 and December 2009 were retrospectively reviewed. Indications for surgery included corneal melt with microperforation (n = 6), keratoprosthesis-associated corneal melt (n = 2), and noninflammatory limbal lesions (n = 2). The grafts were fashioned from full- or partial-thickness tissues using . . .disposable trephines, based on the depth, shape, and size of the defect in the recipient bed, and were secured with multiple interrupted 10/0 nylon sutures. Rate of epithelialization and clarity of the grafts at the last visit were assessed retrospectively. Results All but 1 graft became epithelialized between postoperative 1st and 13th days. Corneal inflammation progressed in the 1 patient with Boston type 1 keratoprosthesis- associated corneal melt, probably attributable to the progression of underlying Sjgren syndrome, despite initiation of systemic immunomodulatory treatment, and required replacement of the device. The donor tissues remained clear in all the other cases over a period of 7 to 15 months. No immune rejection, infection, significant opacification, or neovascularization of the donor tissues were noted during a follow-up period. Conclusions VisionGraft may be considered in lieu of fresh donor corneas for lamellar corneal patch grafts because of its availability, easy handling, and lack of immunogenicity Daha fazlası Daha az