Person: DÜNDAR, TOLGA TURAN
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Publication Open Access A Rare Cause of Headache in the Emergency Department: Intraventricular Epidermoid Cyst Rupture With Hydrocephalus.(2016-07-01) YIGIT, M; Seyithanoglu, MEHMET HAKAN; DUNDAR, TOLGA TURAN; SOGUT, O; YIGIT, E; SEYİTHANOĞLU, MEHMET HAKAN; DÜNDAR, TOLGA TURANLateral intraventricular tumors are not frequently observed. Since these tumors grow linearly rather than exponentially, they grow gradually and thus do not cause mass effects and hydrocephalus. This study is the case report of a rare great volume left intraventricular epidermoid cyst rupture. The tumor was found to be associated with mass effect on neighboring structures and hydrocephalus.Publication Open Access Dexpanthenol and ascorbic acid ameliorate colistin-induced nephrotoxicity in rats.(2021-01-01T00:00:00Z) Aslan, T; Guler, E M; Dundar, T; Cakir, A; Gulgec, A S; Huseyinbas, O; Celikten, M; Coban, G; Hakyemez, I N; Kocyigit, ABDÜRRAHİM; Durdu, B; DÜNDAR, TOLGA TURAN; KOÇYİĞİT, ABDÜRRAHİMObjective: Colistin is a potent antibiotic which is mainly preferred in the treatment of multidrug-resistant (MDR) gram-negative bacilli. However, due to the increased risk of acute kidney injury following its use, the clinical application is limited. This nephrotoxicity is known to be induced by oxidative stress and related inflammation. In this study on rats, potent antioxidants Dexpanthenol (DEX) and Ascorbic acid (Vit C) have been administered in combination with Colistin to find out whether they would weaken Colistin's nephrotoxic effects. Materials and methods: Inflammation biomarkers were studied with enzyme-linked immunosorbent assay (ELISA) kits, and oxidative stress biomarkers were studied with different photometric methods in blood and tissue samples taken after treatment with DEX and Vit C in rats with colistin nephrotoxicity. In addition, inflammation and necrosis in the kidney tissues were examined pathologically. Results: It has been observed in the serum and tissue samples that DEX and Vit C decrease oxidative stress and inflammation biomarkers, therefore acting as nephroprotective agents. Conclusions: These compounds have been found to ameliorate the nephrotoxic effects of Colistin, which were demonstrated in the rats treated with Colistin, as well as the combinations.Publication Open Access Investigation of Brain Impairment Using Diffusion-Weighted and Diffusion Tensor Magnetic Resonance Imaging in Experienced Healthy Divers.(2018-11-17) SEYITHANOĞLU, MEHMET HAKAN; ABDALLAH, ANAS ABDELRAHIM SA; Dündar, TOLGA TURAN; KITIŞ, SERKAN; ARALAŞMAK, AYŞE; Gündağ, Papaker; SASANI, H; SEYİTHANOĞLU, MEHMET HAKAN; ABDALLAH, ANAS ABDELRAHıM SA; DÜNDAR, TOLGA TURAN; KİTİŞ, SERKAN; ARALAŞMAK, AYŞE; GUNDAG, MELİHABackground: The aim of this study was to understand the changes of decompression illness in healthy divers by comparing diffusion-weighted (DWI) and diffusion tensor MRI findings among healthy professional divers and healthy non-divers with no history of diving. Material/Methods: A total of 26 people were recruited in this prospective study: 11 experienced divers with no history of neurological decompression disease (cohort) and 15 healthy non-divers (control). In all study subjects, we evaluated apparent diffusion coefficient (ADC) and type of diffusion tensor metric fractional anisotropy (FA) values of different brain locations (e.g., frontal and parieto-occipital white matter, hippocampus, globus pallidus, putamen, internal capsule, thalamus, cerebral peduncle, pons, cerebellum, and corpus callosum). Results: ADC values of hippocampus were high in divers but low in the control group; FA values of globus pallidus and putamen were lower in divers compared to the control group. DWI depicted possible changes due to hypoxia in different regions of the brain. Statistically significant differences in ADC values were found in hypoxia, particularly in the hippocampus (p=0.0002), while FA values in the globus pallidus and putamen were statistically significant (p=0.015 and p=0.031, respectively). We detected forgetfulness in 6 divers and deterioration in fine-motor skills in 2 divers (p=0.002 and p=0.17, respectively). All of them were examined using neuro-psychometric tests. Conclusions: Repeated hyperbaric exposure increases the risk of white matter damage in experienced healthy divers without neurological decompression illness. The hippocampus, globus pallidus, and putamen are the brain areas responsible for memory, learning, navigation, and fine-motor skills and are sensitive to repeated hyperbaric exposurePublication Open Access Machine Learning-Based Surgical Planning for Neurosurgery: Artificial Intelligent Approaches to the Cranium(2022-04-01T00:00:00Z) Dündar, Tolga Turan; Yurtsever, İsmail; Kurt Pehlivanoğlu, Meltem; Yıldız, Uğur; Eker, Ayşegül; Demir, Mehmet Ali; Mutluer, Ahmet Serdar; Tektaş, Recep; Kazan, Mevlude Sila; Kitiş, Serkan; Gokoglu, Abdulkerim; Doğan, İhsan; Duru, Nevcihan; DÜNDAR, TOLGA TURAN; YURTSEVER, İSMAİL; KİTİŞ, SERKANObjectives: Artificial intelligence (AI) applications in neurosurgery have an increasing momentum as well as the growing number of implementations in the medical literature. In recent years, AI research define a link between neuroscience and AI. It is a connection between knowing and understanding the brain and how to simulate the brain. The machine learning algorithms, as a subset of AI, are able to learn with experiences, perform big data analysis, and fulfill human-like tasks. Intracranial surgical approaches that have been defined, disciplined, and developed in the last century have become more effective with technological developments. We aimed to define individual-safe, intracranial approaches by introducing functional anatomical structures and pathological areas to artificial intelligence. Methods: Preoperative MR images of patients with deeply located brain tumors were used for planning. Intracranial arteries, veins, and neural tracts are listed and numbered. Voxel values of these selected regions in cranial MR sequences were extracted and labeled. Tumor tissue was segmented as the target. Q-learning algorithm which is a model-free reinforcement learning algorithm was run on labeled voxel values (on optimal paths extracted from the new heuristic-based path planning algorithm), then the algorithm was assigned to list the cortico-tumoral pathways that aim to remove the maximum tumor tissue and in the meantime that functional anatomical tissues will be least affected. Results: The most suitable cranial entry areas were found with the artificial intelligence algorithm. Cortico-tumoral pathways were revealed using Q-learning from these optimal points. Conclusions: AI will make a significant contribution to the positive outcomes as its use in both preoperative surgical planning and intraoperative technique equipment assisted neurosurgery, its use increasedPublication Metadata only Comparison of TOF MRA, Contrast-Enhanced MRA and Subtracted CTA from CTP in Residue Evaluation of Treated Intracranial Aneurysms(2018-01-01) Dundar, TOLGA TURAN; Kits, Serkan; Ozdemir, HÜSEYİN; Seyithanoglu, MEHMET HAKAN; Uysal, Omer; Toprak, HÜSEYİN; Ozek, ERDİNÇ; Alkan, ALPAY; DÜNDAR, TOLGA TURAN; ARALAŞMAK, AYŞE; ÖZDEMİR, HÜSEYIN; SEYİTHANOĞLU, MEHMET HAKAN; UYSAL, ÖMER; TOPRAK, HÜSEYİN; KİTİŞ, SERKAN; ÖZEK, ERDİNÇ; ALKAN, ALPAYAIM: To compare effectiveness of contrast-enhanced magnetic resonance angiography (CE-MRA), 3D-Time-of-flight magnetic resonance angiography (3D-TOF-MRA) and subtracted computed tomography angiography from computed tomography perfusion (sub-CTA) in residue evaluation of intracranial aneurysms treated either with coiling or clipping.Publication Open Access Glioblastoma Stem Cells and Comparison of Isolation Methods.(2019-06-01) Kaynar, MY; Dundar, TOLGA TURAN; Hatiboglu, MA; Ergul, Z; Sozen, E; Seyithanoglu, MH; Tuzgen, S; Karaoz, E; DÜNDAR, TOLGA TURAN; HATİBOĞLU, MUSTAFA AZİZ; SEYİTHANOĞLU, MEHMET HAKANBackground: Glioblastoma (GBM) is the most aggressive and the most common primary brain tumor. Over the last few years, studies have identified many genetical and phenotypical molecular situations for developing new treatment modalities in patients with GBM. Nevertheless, main problem for the GBM is radio-chemotherapy resistance and relapse after the surgery. The identification of glioma stem cells and microenvironmental influences has created a paradigm shift in targets of therapy. Current studies have shown that glioma stem cell is responsible for aggressiveness, recurrence and resistance to therapy of GBM. GBM stem cell isolated from human GBM multiforme fresh tissue samples is important both for curative therapeutic options and personalized targeted therapy. The purpose of this study was to determine the most suitable isolation method of GBM stem cells (GSCs). Methods: Tumor tissue sample was obtained during the surgical resection of lesion in patients with the diagnosis of GBM. Tumor stem cell isolation from tissue was performed in three different ways: 1) GBM cell isolation with trypsin; 2) GBM cell isolation with brain tumor dissociation Kit (BTD Kit); and 3) GBM cell isolation with tumor dissociation enzyme (TDE). Results: We showed that GSCs were isolated from tumor specimen using flow cytometry and immunofluorescence staining. Our study showed that isolation with BTD Kit is the most suitable method to isolate GBM tissue-derived glial tumor stem cells. Conclusions: The development of alternative personalized therapies targeting brain tumor stem cell is urgently needed. It is important to understand the fundamental mechanisms of driving stem cells. If their life cycle mechanisms can be identified, we can control the growth of GBM.Publication Open Access A Remarkable Age-Related Increase in SIRT1 Protein Expression against Oxidative Stress in Elderly: SIRT1 Gene Variants and Longevity in Human(2015-03-18) Elibol-Can, BİRSEN; Kilic, Ulkan; Gok, Ozlem; DUNDAR, TOLGA TURAN; DUNDAROZ, Mehmet Rusen; Torun, EMEL; Erenberk, UFUK; Uysal, Omer; ERENBERK, UFUK; TORUN, EMEL; ELİBOL, BİRSEN; UYSAL, ÖMER; DÜNDAR, TOLGA TURANAging is defined as the accumulation of progressive organ dysfunction. Controlling the rate of aging by clarifying the complex pathways has a significant clinical importance. Nowadays, sirtuins have become famous molecules for slowing aging and decreasing age-related disorders. In the present study, we analyzed the SIRT1 gene polymorphisms (rs7895833 A>G, rs7069102 C>G and rs2273773 C>T) and its relation with levels of SIRT1, eNOS, PON-1, cholesterol, TAS, TOS, and OSI to demonstrate the association between genetic variation in SIRT1 and phenotype at different ages in humans. We observed a significant increase in the SIRT1 level in older people and found a significant positive correlation between SIRT1 level and age in the overall studied population. The oldest people carrying AG genotypes for rs7895833 have the highest SIRT1 level suggesting an association between rs7895833 SNP and lifespan longevity. Older people have lower PON-1 levels than those of adults and children which may explain the high levels of SIRT1 protein as a compensatory mechanism for oxidative stress in the elderly. The eNOS protein level was significantly decreased in older people as compared to adults. There was no significant difference in the eNOS level between older people and children. The current study is the first to demonstrate age-related changes in SIRT1 levels in humans and it is important for a much better molecular understanding of the role of the longevity gene SIRT1 and its protein product in aging. It is also the first study presenting the association between SIRT1 expression in older people and rs7895833 in SIRT1 gene.Publication Open Access Follow-Up of High-Grade Glial Tumor; Differentiation of Posttreatment Enhancement and Tumoral Enhancement by DCE-MR Perfusion(2022-01-01T00:00:00Z) DÜNDAR, TOLGA TURAN; Cetinkaya, Ezra; YURTSEVER, İSMAİL; Uysal, Ömer; Aralaşmak, Ayşe; DÜNDAR, TOLGA TURAN; ÇETİNKAYA, EZRA; YURTSEVER, İSMAİL; UYSAL, ÖMERPurpose: To search for the utility of DCE-MRP to differentiate between posttreatment enhancement (PT) and tumoral enhancement (TM) in high-grade glial tumors. Materials and methods: Thirty-four patients with glioma (11 grade 3; 23 grade 4) were enrolled. Enhancement in the vicinity of the resection cavity demonstrated by DCE-MRP was taken into consideration. Based on the follow-up scans, reoperation or biopsy results, the enhancement type was categorized as PT or TM. Measurements were performed at the enhancing area near the resection cavity (ERC), nearby (NNA) and contralateral nonenhancing areas (CLNA). Perfusion parameters of the ERC were also subtracted from NNA and CLNA. Intragroup comparison (paired sample t-test) and intergroup comparison (Student's t-test) were made. Results: There were 7 PTs and 27 TMs. In the PT, the subtracted values of Ve and IAUC from the CLNA and NNA and the subtracted value of Kep from NNA were statistically different. In TM, all metrics were significantly different comparing the CLNA and NNA. Comparing PT with TM, Ktrans, IAUC, Kep, and subtracted values of Ktrans and IAUC from both NNA and CLNA were significantly different. Conclusions: In PT, only Ktrans values did not reveal any difference comparing NNA and CLNA. To differentiate PT from TM, Ktrans, Kep, IAUC, and subtracted values of Ktrans and IAUC from NNA and CLNA can be used. These findings are in concordance with literature.