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Article Citation - WoS: 15Citation - Scopus: 13K+-induced Conformational Changes in the Trimeric Betaine Transporter Betp Monitored by Atr-Ftir Spectroscopy(Elsevier Science Bv, 2013) Korkmaz, Filiz; Ressl, Susanne; Ziegler, Christine; Maentele, Werner; Mäntele, WernerThe trimeric Na+-coupled betaine symporter BetP from Corynebactrium glutamicum adjusts transport activity according to the external osmolality. BetP senses the increasing internal K+ concentration, which is an immediate consequence of osmotic upshift in C. glutamicum. It is assumed that BetP specifically binds potassium to yet unidentified binding sites, thereby inducing conformational changes resulting in activation. Atomic structures of BetP were obtained in the absence of potassium allowing only a speculative glimpse on a putative mechanism of K+-induced transport activation. The structural data suggest that activation in BetP is crucially linked to its trimeric state involving an interaction network between several arginines and glutamates and aspartates. Here, we describe the effect of K+-induced activation on the specific ionic interaction sites in terminal domains and loops and on the protomer-protomer interactions within the trimer studied by ATR-FTIR spectroscopy. We suggest that arginine and aspartate and/or glutamate residues at the trimeric interface rearrange upon K+-induced activation, although they remain assembled in an interaction network. Our data propose a two-step mechanism comprising first a change in solvent exposure of charged residues and second a modification of their interaction sites in a partner-switching manner. FTIR reveals a higher alpha-helical content than expected from the X-ray structures that we attribute to the structurally unresolved N-terminal domain modulating regulation. In situ H-1/H-2 exchange studies point toward an altered exposure of backbone regions to buffer solution upon activation, most likely due to conformational changes in both terminal domains, which further affects ionic interactions within the trimer. (C) 2013 Elsevier B.V. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 5Investigation of the Effect of Hyperthyroidism on Endoplasmic Reticulum Stress and Transient Receptor Potential Canonical 1 Channel in the Kidney(Tubitak Scientific & Technological Research Council Turkey, 2021) Aykanat, Nuriye Ezgi Bektur; Şahin, Erhan; Kaçar, Sedat; Bağcı, Rıdvan; Karakaya, Şerife; Dönmez, Dilek Burukoğlu; Şahintürk, Varol; Bektur Aykanat, Nuriye Ezgi; Burukoğlu Dönmez, Dilek; Bektur, EzgiBackground/aim: Hyperthyroidism is associated with results in increased glomerular filtration rate as well as increased renin-angiotensin-aldosterone activation. The disturbance of Ca2+ homeostasis in the endoplasmic reticulum (ER) is associated with many diseases, including diabetic nephropathy and hyperthyroidism. Transient receptor potential canonical 1 (TRPC1) channel is the first cloned TRPC family protein. Although it is expressed in many places in the kidney, its function is uncertain. TRPC1 is involved in regulating Ca2+ homeostasis, and its upregulation increases ER Ca2+ level, activates the unfolded protein response, which leads to cellular damage in the kidney. This study investigated the role of TRPC1 in the kidneys of hyperthyroid rats in terms of ER stress markers that are glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), (protein kinase R (PKR)-like endoplasmic reticulum kinase) (PERK), Inositol-requiring enzyme 1 (IRE1). Materials and methods: Twenty male rats were assigned into control and hyperthyroid groups (n = 10). Hyperthyroidism was induced by adding 12 mg/L thyroxine into the drinking water of rats for 4 weeks. The serum-free T3 and T4 (fT3, fT4), TSH, blood urea nitrogen (BUN), and creatinine levels were measured. The histochemical analysis of kidney sections for morphological changes and also immunohistochemical and western blot analysis of kidney sections were performed for GRP78, ATF6, PERK, IRE1, TRPC1 antibodies. Results: TSH, BUN, and creatinine levels decreased while fT3 and fT4 levels increased in the hyperthyroid rat. The morphologic analysis resulted in the capillary basal membrane thickening in glomeruli and also western blot, and immunohistochemical results showed an increase in TRPC1, GRP78, and ATF6 in the hyperthyroid rat (p < 0.05). Conclusion: In conclusion, in our study, we showed for the first time that the relationship between ER stress and TRPC1, and their increased expression caused renal damage in hyperthyroid rats.Key words: Hyperthyroidism, endoplasmic reticulum (ER) stress, transient receptor potential canonical 1 (TRPC1), kidney, ratArticle Citation - WoS: 11Citation - Scopus: 14Informal Payments in Health Systems: Purpose and Occurrences in Turkey(Routledge Journals, Taylor & Francis Ltd, 2015) Tengilimoglu, Dilaver; Guzel, Alper; Toygar, Anil; Akinci, Fevzi; Dziegielewski, Sophia F.Informal payments constitute a significant portion of out-of-pocket payments in health systems, especially in developing countries. This study examined the current status of informal payments in Turkey and the opinions, attitudes, and behavior of individuals toward informal payments. To examine this concept, 1,033 residents in Ankara, the capital city of Turkey, were surveyed. The 28-item questionnaire used in data collection was developed based on previous research and expert opinions. The data analysis revealed that approximately 29% of the study participants made informal payments in return for the medical service they received. Three out of 4 people who made informal payments were from a low-income group. Informal payments were made in the form of cash prior to medical procedures and also as gifts following the procedures. Future recommendations for health policymakers include designing a new patient copay mechanism where informal payments can be effectively incorporated into the formal payment system, assistance to low-income individuals, and improvement in current medical staff salaries that would discourage taking such payments.Article Citation - WoS: 3Citation - Scopus: 3Expectancy From, and Acceptance of Augmented Reality in Dental Education Programs: a Structural Equation Model(Wiley, 2024) Toker, Sacip; Akay, Canan; Basmaci, Fulya; Kilicarslan, Mehmet Ali; Mumcu, Emre; Cagiltay, Nergiz ErcilObjectiveDental schools need hands-on training and feedback. Augmented reality (AR) and virtual reality (VR) technologies enable remote work and training. Education programs only partially integrated these technologies. For better technology integration, infrastructure readiness, prior-knowledge readiness, expectations, and learner attitudes toward AR and VR technologies must be understood together. Thus, this study creates a structural equation model to understand how these factors affect dental students' technology use.MethodsA correlational survey was done. Four questionnaires were sent to 755 dental students from three schools. These participants were convenience-sampled. Surveys were developed using validity tests like explanatory and confirmatory factor analyses, Cronbach's alpha, and composite reliability. Ten primary research hypotheses are tested with path analysis.ResultsA total of 81.22% responded to the survey (755 out of 930). Positive AR attitude, expectancy, and acceptance were endogenous variables. Positive attitudes toward AR were significantly influenced by two exogenous variables: infrastructure readiness (B = 0.359, beta = 0.386, L = 0.305, U = 0.457, p = 0.002) and prior-knowledge readiness (B = -0.056, beta = 0.306, L = 0.305, U = 0.457, p = 0.002). Expectancy from AR was affected by infrastructure, prior knowledge, and positive and negative AR attitudes. Infrastructure, prior-knowledge readiness, and positive attitude toward AR had positive effects on expectancy from AR (B = 0.201, beta = 0.204, L = 0.140, U = 0.267, p = 0.002). Negative attitude had a negative impact (B = -0.056, beta = -0.054, L = 0.091, U = 0.182, p = 0.002). Another exogenous variable was AR acceptance, which was affected by infrastructure, prior-knowledge preparation, positive attitudes, and expectancy. Significant differences were found in infrastructure, prior-knowledge readiness, positive attitude toward AR, and expectancy from AR (B = 0.041, beta = 0.046, L = 0.026, U = 0.086, p = 0.054).ConclusionInfrastructure and prior-knowledge readiness for AR significantly affect positive AR attitudes. Together, these three criteria boost AR's potential. Infrastructure readiness, prior-knowledge readiness, positive attitudes toward AR, and AR expectations all increase AR adoption. The study provides insights that can help instructional system designers, developers, dental education institutions, and program developers better integrate these technologies into dental education programs. Integration can improve dental students' hands-on experience and program performance by providing training options anywhere and anytime.Article Citation - WoS: 11Citation - Scopus: 14Card Spending Dynamics in Turkey During the Covid-19 Pandemic(Central Bank Republic Turkey, 2021) Kantur, Zeynep; Özcan, GülserimThis paper provides an extensive analysis of card spending during the COVID-19 pandemic in Turkey by using weekly aggregated and sectoral credit and debit card spending data from March 2014 to December 2020. At an aggregated level, we show that aggregate demand decreases significantly at the early stages of COVID-19 and seems to reinstate its pre-COVID trend. However, when we include the pre-existing conditions of Turkey, the 2018 currency crisis, we observe that the recovery in demand is not that strong. To highlight the underlying reasons for structural change in aggregate demand, we estimate the model with stringency index and unemployment-related search index. The estimated model indicates that containment measures and restrictions and fear of job/income loss mainly explain the overall impact of COVID-19 on aggregate demand. We also examined sectoral data to understand aggregate demand dynamics better. Only stable and delayable sector groups have reached a trend above their pre-pandemic trajectories. However, the social and work-related sectors are far from their respective pre-pandemic trend.Article Differences of Microbial Growth and Biofilm Formation Among Periprosthetic Joint Infection-Causing Species: an Animal Study(Springer Science and Business Media Deutschland GmbH, 2025) Ertan, M.B.; Ayduğan, M.Y.; Evren, E.; İnanç, İ.; Erdemli, E.; Erdemli, B.Purpose: The most frequently used surgical procedures for periprosthetic joint infections (PJIs) are debridement, antibiotics, and implant retention (DAIR), as well as single- or two-stage revision arthroplasty. The choice of surgery is made depending on the full maturation of the biofilm layer. The purpose of this study was to evaluate the biofilm formation and microbial growth using common PJI-causing agents and compare its development on the implant surface. Methods: The in vivo study was performed using 40 Sprague–Dawley rats divided into five groups (n = 8/group): Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Candida albicans, and control. Six standard titanium alloy discs were placed into the subcutaneous air pouches of the interscapular areas of the rats. After the inoculation of microorganisms, disc and soft tissue cultures were collected at 2-week intervals for 6 weeks, and the microbial load and the microscopic appearance of the biofilm were compared. Results: The disc samples from the S. aureus group had the highest infection load at all time points; however, in soft tissue samples, this was only observed at week 4 and 6. Electron microscopic images showed no distinctive differences in the biofilm structures between the groups. Conclusion: S. aureus microbial burden was significantly higher in implant cultures at week 2 compared to other PJI-causing agents examined. These results may explain the higher failure rate seen if the DAIR procedure was performed at < 3–4 weeks after the PJI symptom onset and support the observation that DAIR may not be effective against PJIs caused by S. aureus. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.Article Citation - Scopus: 19Pulmonary rehabilitation principles in SARS-COV-2 infection (COVID-19): The revised guideline for the acute, subacute, and post-COVID-19 rehabilitation(Turkish Society of Physical Medicine and Rehabilitation, 2021) Aytür,Y.K.; Köseoglu,B.F.; Taşkıran,Ö.Ö.; Gökkaya,N.K.O.; Delialioğlu,S.Ü.; Tur,B.S.; Tıkız,C.Coronavirus disease 2019 (COVID-19) is a contagious infection disease, which may cause respiratory, physical, psychological, and generalized systemic dysfunction. The severity of disease ranges from an asymptomatic infection or mild illness to mild or severe pneumonia with respiratory failure and/or death. COVID-19 dramatically affects the pulmonary system. This clinical practice guideline includes pulmonary rehabilitation (PR) recommendations for adult COVID-19 patients and has been developed in the light of the guidelines on the diagnosis and treatment of COVID-19 provided by the World Health Organization and Republic of Turkey, Ministry of Health, recently published scientific literature, and PR recommendations for COVID-19 regarding basic principles of PR. This national guideline provides suggestions regarding the PR methods during the clinical stages of COVID-19 and post-COVID-19 with its possible benefits, contraindications, and disadvantages. © 2021 All right reserved by the Turkish Society of Physical Medicine and RehabilitationArticle Citation - WoS: 28Citation - Scopus: 28Photoelectronic and Electrical Properties of Cuin5s8< Single Crystals(Wiley-v C H verlag Gmbh, 2003) Qasrawi, AF; Gasanly, NMTo identify the impurity levels in CuIn5S8 single crystals, the dark electrical conductivity and photoconductivity measurements were carried out in the temperature range of 50-460 K. The data reflect the intrinsic and extrinsic nature of the crystals above and below 300 K, respectively. Energy band gaps of 1.35 and 1.31 eV at 0 K and 300 K, were defined from the dark conductivity measurements and the photocurrent spectra, respectively. The dark and photoconductivity data in the extrinsic temperature region reflect the existence of two independent donor energy levels located at 130 and 16 meV. The photocurrent-illumination intensity dependence (F) follows the law I(ph)alphaF(gamma), with gamma being 1.0, 0.5 and 1.0 at low, moderate and high intensities indicating the domination of monomolecular, bimolecular and strong recombination at the surface, respectively. In the intrinsic region and in the temperature region where the shallow donor energy level 16 meV is dominant, the free electron life time, tau(n), is found to be constant with increasing F. In the temperature region 140 K < T < 210 K, the free electron life time increases with increasing illumination intensity showing the supralinear character. Below 140 K, tau(n) decrease with decreasing illumination intensity. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article Citation - WoS: 1Citation - Scopus: 2Design of a Ratio Control Algorithm for a Fluid Catalytic Cracking System in an Universal Oil Product Context(Maik Nauka/interperiodica/springer, 2024) Atiyah, Safa Khalaf; Aljanabi, Ahmed Yaseen Ali; Ahmed, Mohammed S.; Al-Timimi, Buthainah Ali; Mhmood, Ali H.This paper delves into the intricate dynamics of industrial fluid catalytic cracking, a pivotal process in refining universal oil products (UOP). At the core of this investigation is the endeavor to derive a comprehensive mathematical model that captures the essence of mass and energy balances within a UOP fluid catalytic cracking unit. The study's central objective is to explore and apply a ratio control algorithm in two distinct operational scenarios. In the first scenario, the ratio controller is strategically positioned after the control valve for the regenerator's input air, while in the second, it precedes the control valve. The primary focus here is the meticulous control of outlet temperatures for both the riser and regenerator reactors. Leveraging the capabilities of MATLAB software, the research methodically simulates the fluid catalytic cracking process. It introduces variables such as the gas oil feed rate, along with the temperatures of the gas oil feed and air, to rigorously test the efficacy of the proposed ratio control algorithm. The results of this investigation reveal a notable superiority of the ratio control in case one over case two. In the riser and regenerator reactors, this advantage is demonstrated by improved stability and operational efficiency, as evidenced by lower integral absolute error (IAE) readings and a quicker approach to the intended setpoint temperatures.Article Citation - WoS: 9Citation - Scopus: 9Structural and Optoelectronic Properties of Cds/Y Thin Films(Elsevier Science Sa, 2019) Qasrawi, A. F.; Abed, Tamara Y.In the current study, the structural, optical, photoelectrical and electrical properties of CdS/Y/CdS thin films are investigated. The current design include the evaporation of a layer of 70 nm thick yttrium between two layers of CdS. Each CdS layer is of thickness of 500 nm. It is observed that the yttrium slab increased the microstrain, defect density, stacking faults and decreased the grain size and redshifts the indirect allowed transitions energy band gap of CdS. In addition an enhancement by similar to 5 times in the light absorbability is detected at 1.74 eV. The enhanced absorbance results in increasing the photocurrent by similar to 21 times and changed the recombination mechanism from a trap assisted recombination to supralinear recombination mechanisms. Moreover, the ac signal analysis in the frequency domain of 10-1800 MHz has shown that the yttrium forces the CdS to exhibit negative capacitance effect and make it behave as band stop filter with notch frequency of 1520 MHz. The quality of the CdS/Y/CdS films as microwave cavities are screened by the evaluation of the return loss which revealed good features of the nanostructured films as microwave receivers.
