Tıbbi Görüntüleme Teknikleri Bölümü Koleksiyonu
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- ItemMultimodal imaging analysis of autosomal recessive Parkinson’s disease(Springer, 2025-04) Soydaş Turan, Başak; Yalçın Çakmaklı, Gül; Lay Ergün, Eser; Daşgın, Hacer; Karlı Oğuz, Kader; Elibol, Bülent; Uğur, Ömer; Volkan Salancı, Bilge; 396621Objective Pathophysiological backgrounds of idiopathic Parkinson’s disease (IPD) and autosomal recessive monogenic Parkinson’s disease (AR-PD) have common features that can be assessed through multimodal imaging. In this study, the striatal and myocardial dopaminergic innervation, brain 18F-FDG metabolism, resting-state functional activity of basal ganglia network (BGN) and white-matter (WM) microstructure were evaluated in AR-PD with respect to IPD, to investigate whether AR-PD can be subtyped as “brain-first” parkinsonism according to recent etiopathogenetic classification effort. Methods Forty patients (17 with Parkin, 3 with DJ-1 mutations and 20 with IPD) were included. Striatal dopaminergic innervation was assessed semi-quantitatively by 18F-DOPA PET, and cardiac 18F-DOPA uptake was also evaluated. Brain 18F-FDG PET images were evaluated visually. Resting-state functional MRI and diffusion tensor imaging (DTI) were used to assess the BGN activity and WM microstructural alterations. Results AR-PD patients showed significantly decreased 18F-DOPA uptake in caudate corpus compared to both IPD and controls, with a more symmetrical striatal dopaminergic denervation. Myocardial 18F-DOPA uptake in AR-PD was similar to controls, while it was significantly reduced in IPD. There was no significant difference in cortical 18F-FDG metabolism and functional activity of BGN between PD groups. The DTI data revealed more extensive WM microstructural damage in AR-PD compared to IPD. Conclusions AR-PD group showed additional significant decreased 18F-DOPA uptake in caudate corpus and more symmetrical striatal denervation. Additionally, relatively preserved myocardial innervation, cortical metabolic and WM microstructural changes suggest the possibility of “brain-first” type progression in AR-PD. Also, 18F-DOPA PET/CT may be a practical tool for evaluating dopaminergic innervation of striatum and heart together, but further evaluation is needed in this area.
- ItemFabrication of Al/n-GaN/p-Si/Al diodes by thermal evaporation and evaluation of effect of gamma irradiation on device properties(Elsevier, 2024-12) Olkun, Ali; Kaplan, Hüseyin Kaan; Akay, Sertan Kemal; Sarsıcı, Serhat; Erdoğan, Nursev; 414025This study investigates the impact of gamma-irradiation on the material and device properties of Al/n-GaN/p-Si/Al heterojunction diodes. GaN thin films were deposited on glass and p-Si substrates using thermal evaporation, followed by annealing at 450 degrees C. The diodes were subjected to gamma-irradiation doses of 0, 3, and 6 kGy. X-ray diffraction (XRD) measurements revealed significant structural changes, including phase transitions influenced by radiation. Electrical characteristics were assessed through current-voltage (I-V) measurements within the +/- 2 V range. Notably, the ideality factor for the annealed diodes improved from 6.60 to 4.62 and 3.85 with increased gamma-irradiation. The barrier height was determined to be 0.85 eV, and it did not exhibit a significant change upon gamma-irradiation dose. The results provided valuable insights into the response of heterojunction diodes to radiation exposure, aiding in the understanding and potential improvement of the radiation resistance of GaN-based electronic devices.
- ItemThe Role of Advanced Glycation End Products in Saphenous Vein Graft Failure(Karger, 2024-10) Akgümüş, Alkame; Boyraz, Bedrettin; Balun, Ahmet; 313898Objective: We aimed to investigate the relationship between advanced glycation end product (AGE) levels in patients with saphenous vein graft (SVG) failure and in patients without SVG failure. Subjects and Methods: In our study, 55 patients with a history of previous coronary artery bypass grafting (CABG) surgery, who subsequently underwent coronary angiography for any reason and were found to have either SVG occlusion or significant lesions, were included as study patients. Additionally, 55 patients who have had CABG surgery without SVG failure for at least 1 year served as the control group. AGE values of the patients were measured using the skin autofluorescence method. Results: In our study results, we observed a significant difference in AGE levels between the two groups of patients with similar demographic characteristics (SVG failure groups AGE 3.2 [2.8–3.6] vs. control groups AGE 2.4 [2.1–2.7] p < 0.001). In the receiver operating characteristic curve analysis, we determined the ability of AGE levels to detect SVG failure with an area under the curve of 0.869. We found that in patients with AGE >3, it could detect SVG failure with a sensitivity of 70.9% and a specificity of 87.3%. Conclusions: Our results demonstrate that AGE levels can predict SVG failure risk inexpensively, easily, and quickly.
- ItemExploring Cognitive Enhancements and Default Mode Network Connectivity in Relapsing-Remitting Multiple Sclerosis: Insights from a Prospective Study Investigating the MIND Diet(Sage, 2024-09) Demirel, Mert; Daşgın, Hacer; Acar, Nazire Pınar; Özçelik-Eroğlu, Elçin; Atabilen, Büşra; Ertuğrul, Aygün; Akdevelioğlu, Yasemin; Oğuz, Kader Karlı; Tuncer, Meryem Aslı; 396621The potential therapeutic impact of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet on relapsing-remitting multiple sclerosis (RRMS) remains an underexplored area. Objectives/Aims: This study aims to evaluate the influence of the MIND diet on RRMS by examining neurological, cognitive, and functional magnetic resonance imaging (fMRI) parameters. Methods: Seventeen early-stage RRMS patients (aged 20-40, disease duration < 10 years, Beck Depression Inventory Score < 17) underwent MRI at baseline and following a 9-month adherence to the MIND diet. They were matched with 10 healthy controls. Diet adherence was assessed using the MIND Diet scale score. MRI encompassed structural and resting-state fMRI (RS-fMRI) sequences. Neurological evaluation (Expanded Disability Status Scale [EDSS], Timed 25-Foot Walk [T25W], 9-Hole Peg Test [9HPT]), and cognitive assessments (Mini-Mental State Examination [MMSE], Rey Auditory Verbal Learning Test [AVLT], phonemic and semantic fluency, forward and backward digit span tests [FDST, BDST]) were conducted. Functional connectivity was assessed using seed-based correlation (SBC) and global correlation by general linear model (GLM), focusing on Default Mode Network (DMN), Central Executive Network (CEN), Dorsal Attention Network (DAN), Salience Network (SN), Visual Network (VN), and Sensorimotor Network (SMN). Results: Patients exhibited high adherence to the diet throughout the 9-month period. Significant improvements were observed in dominant hand 9-HPT (p=0.023) and AVLT parameters (p<0.001), except delayed recall (p=0.982), following the intervention. Increased connectivity within the whole brain was noted in the left frontal orbital cortex of the 9th-month group compared to healthy controls (p=0.000005). Moreover, RRMS patients in the 9th-month group displayed enhanced functional connectivity in the bilateral caudate, bilateral pallidum, and right putamen within the DMN compared to baseline (p=0.000034). Conclusion: The findings of this study suggest potential cognitive benefits of the MIND diet, as evidenced by improvements in AVLT scores. Furthermore, the observed alterations in Default Mode Network (DMN) connectivity in RRMS patients following the dietary intervention indicate a promising avenue for further investigation into cognitive deficit management in this population
- ItemThe Relationship between Resistant Hypertension and Advanced Glycation End-Product Levels Measured Using the Skin Autofluorescence Method: A Case–Control Study(MDPI, 2023-10) Peker, Tezcan; Boyraz, Bedrettin; 313898Resistant hypertension is hypertension that cannot be controlled despite the use of three antihypertensive drugs, one of which is a diuretic. Resistant hypertension often coexists with advanced age, obesity, smoking, and diabetes. Advanced glycation end products (AGEs) are substances that are generated as a result of the glycation of proteins, lipids, and nucleic acids due to conditions such as hyperlipidemia, oxidative stress, and hyperglycemia. There are studies showing the relationships between AGE levels and aortic stiffness, hypertension, and microvascular and macrovascular complications in diabetes. In our study, we examined the relationship between resistant hypertension and AGE levels. Our study was planned as a case–control study, and 88 patients with resistant hypertension were included in the focus group, while 88 patients with controlled hypertension were included in the control group. The AGE levels of the patients were measured using the skin autofluorescence method. AGE levels were found to be significantly higher in patients with resistant hypertension than those recorded in the control group. A significant increase in AGE levels was also observed in patients with resistant hypertension and without diabetes compared with the control group. The levels of AGEs, which can be measured cheaply, noninvasively, and quickly with the skin autofluorescence method, may provide benefits in identifying these patients with resistant hypertension.
