Sezer D.,Istanbul Science University
Physical Chemistry Chemical Physics | Year: 2014
The recently introduced methodology (Sezer, Phys. Chem. Chem. Phys., 2013, 15, 526) for calculating dynamic nuclear polarization (DNP) coupling factors through synergistic use of molecular dynamics (MD) simulations and the analytical model of diffusing hard spheres with spins at their centers (HSCS) is applied to several nitroxides in water. Computations with one TEMPONE and one TEMPOL in water agree with experiments at 0.35 T and 3.4 T, respectively. At 9.2 T the predicted coupling factors are larger by about 50% than the experimental numbers obtained with 1 M TEMPOL solution. MD simulations at this elevated concentration reveal nanoscopic TEMPOL clusters and qualitatively explain the lower experimental values. Comparing the dynamics from the MD simulations with those of the HSCS model, the assumption of centered spins is shown to be too limiting even for small molecules like TEMPOL and water. Using the available extension of the HSCS model to off-centered spins, the current procedure for analyzing hydration water dynamics from Overhauser DNP measurements on spin-labeled proteins is revisited. © 2014 the Owner Societies.
Kibaroglu A.,Istanbul Science University
Water International | Year: 2015
This article analyzes Turkey’s transboundary water policy by examining its institutional framework and basic principles. It explores the reasons why Turkey voted against the UN Watercourses Convention. Turkey’s harmonization with the water law of the European Union is also scrutinized with an aim to assess its implications for transboundary water policy making. Turkish water diplomacy faces new challenges, such as the devastating impacts of prolonged droughts as well as ongoing instability and conflicts in Syria and Iraq. Hence, it is imperative for Turkey to systematically reconcile its water policy objectives in accordance with the global norms that are adopted in this field. © 2014, © 2014 International Water Resources Association.
Diz-Kucukkaya R.,Istanbul Science University
Hematology / the Education Program of the American Society of Hematology. American Society of Hematology. Education Program | Year: 2013
Inherited platelet disorders (IPDs) are a heterogeneous group of diseases affecting platelet production, morphology, and function. The degree of thrombocytopenia and functional abnormality of platelets determines the clinical manifestations. Although severe deficiencies may cause excessive bleeding beginning in early childhood, most of IPDs have mild bleeding tendencies and therefore are not always easy to distinguish from acquired platelet disorders. The diagnosis of IPD may require extensive laboratory investigation, because current routine laboratory tests are not satisfactory for differential diagnosis in some cases, and most of the specific tests are not readily available in many countries. This review summarizes the classification and clinical and molecular characteristics of known IPDs, including Bernard-Soulier syndrome and Glanzmann thrombasthenia, with a focus on current challenges in the laboratory diagnosis and management of bleeding in these patients.
Ozturk A.,Abant Izzet Baysal University |
Ucsular F.D.,Istanbul Science University
Clinical Rehabilitation | Year: 2011
Objective: To test the hypothesis that, in comparison with those in a control group, community-dwelling wheelchair users in Turkey who have completed the Wheelchair Skills Training Program have better total percentage performance and safety scores on the Wheelchair Skills Test. Design: Randomized controlled trial. Subjects: The study group comprised individuals (n = 24) who have to use a wheelchair for mobility in daily life. The subjects were randomly allocated to training (n = 14) and control groups (n = 10). Interventions: The training group attended a skill training session three times a week for four weeks. The control group did not participate in the training. Main outcome measures: At the beginning of the study, subjects underwent a Wheelchair Skills Test (version 4.1), which evaluated their performance and safety for a range of skills. The test was repeated at the end of the study. Results: The mean ± SD total percentage Wheelchair Skills Test performance scores increased significantly in both the training group (P = 0.002) and control group (P = 0.01), although the training group increased to a greater extent (P = 0.034). The training group's mean ± SD total percentage Wheelchair Skills Test safety scores increased significantly (P = 0.001), but there was no significant change in the control group. A statistically significant improvement was found between the total percentage Wheelchair Skills Test safety scores in the training group compared with the control group (P = 0.001). Conclusion: Community-living wheelchair users who received wheelchair skills training increased their total performance and safety scores to a greater extent than a control group. © The Author(s) 2010.
Balci C.,Istanbul Science University
Diagnostic and Interventional Radiology | Year: 2011
Magnetic resonance imaging (MRI) plays an important role in the assessment of chronic pancreatitis. By standard MRI techniques, decreased parenchymal signal on T1-weighted fat-suppressed images and delayed gradual enhancement on serial contrast enhanced images represent fibrotic changes caused by chronic inflammation. Magnetic resonance cholangiopancreaticography (MRCP) can reveal ductal changes, including side branch ectasias, that are related to tissue fibrosis and destruction. The exocrine function of the gland and an increased number of side branch ectasias can be evaluated with secretin-stimulated MRCP. Diffusion weighted imaging is an emerging technology that can complement standard MRI to assess the parenchymal changes associated with chronic pancreatitis. The same technique can also quantify the parenchymal response to secretin stimulation. This article reviews standard imaging techniques and new advancements in MRI technology as they relate to the assessment of chronic pancreatitis. © Turkish Society of Radiology 2011.
Celik V.,Istanbul Science University |
Yesilyurt E.,Istanbul Science University
Computers and Education | Year: 2013
There is a large body of research regarding computer supported education, perceptions of computer self-efficacy, computer anxiety and the technological attitudes of teachers and teacher candidates. However, no study has been conducted on the correlation between and effect of computer supported education, perceived computer self-efficacy, computer anxiety and attitude to technology and which additionally explains their relationship to each other. This research is conducted in order to test the effect levels among the latent variables of attitude to technology, perceived computer self-efficacy, computer anxiety and the attitude toward doing computer supported education and these latent variables' ratios to each other. For this, eight hypotheses were developed in light of theoretical information by reviewing the literature. This research is done by using Technology Attitude Scale, Perceived Computer Self-Efficacy Scale, Computer Anxiety Scale and The Attitude Scale toward Applying Computer Supported Education. The participant group of the research consists of 471 pre-service teachers. Exploratory factor analyses of scales were analyzed via SPSS 16.0 software. For the confirmatory factor analyses of scales and the structural equation modeling, AMOS 17.0 software was used. The most significant finding of this study is that attitude to technology, perceived computer self-efficacy and computer anxiety are important predictors of teacher candidates' attitude toward using computer supported education.
Akman O.,Istanbul Science University |
Moshe S.L.,Yeshiva University |
Galanopoulou A.S.,Yeshiva University
Neurobiology of Disease | Year: 2014
Seizures are very common in the early periods of life and are often associated with poor neurologic outcome in humans. Animal studies have provided evidence that early life seizures may disrupt neuronal differentiation and connectivity, signaling pathways, and the function of various neuronal networks. There is growing experimental evidence that many signaling pathways, like GABAA receptor signaling, the cellular physiology and differentiation, or the functional maturation of certain brain regions, including those involved in seizure control, mature differently in males and females. However, most experimental studies of early life seizures have not directly investigated the importance of sex on the consequences of early life seizures. The sexual dimorphism of the developing brain raises the question that early seizures could have distinct effects in immature females and males that are subjected to seizures. We will first discuss the evidence for sex-specific features of the developing brain that could be involved in modifying the susceptibility and consequences of early life seizures. We will then review how sex-related biological factors could modify the age-specific consequences of induced seizures in the immature animals. These include signaling pathways (e.g., GABAA receptors), steroid hormones, growth factors. Overall, there are very few studies that have specifically addressed seizure outcomes in developing animals as a function of sex. The available literature indicates that a variety of outcomes (histopathological, behavioral, molecular, epileptogenesis) may be affected in a sex-, age-, region-specific manner after seizures during development. Obtaining a better understanding for the gender-related mechanisms underlying epileptogenesis and seizure comorbidities will be necessary to develop better gender and age appropriate therapies. © 2014 Elsevier Inc.
Buyukgebiz A.,Istanbul Science University
JCRPE Journal of Clinical Research in Pediatric Endocrinology | Year: 2013
Newborn screening (NS) for congenital hypothyroidism (CH) is one of the major achievements in preventive medicine. Most neonates born with CH have normal appearance and no detectable physical signs. Hypothyroidism in the newborn period is almost always overlooked, and delayed diagnosis leads to the most severe outcome of CH, mental retardation, emphasizing the importance of NS. Blood spot thyroid stimulating hormone (TSH) or thyroxine (T4) or both can be used for CH screening. The latter is more sensitive but not cost-effective, so screening by TSH or T4 is used in different programs around the world. TSH screening was shown to be more specific in the diagnosis of CH. T4 screening is more sensitive in detecting especially those newborns with rare hypothalamic-pituitary-hypothyroidism, but it is less specific with a high frequency of false positives mainly in low birth weight and premature infants. The time at which the sample is taken may vary. In the majority of the centers, blood is obtained from a heel prick after 24 hours of age to minimize the false positive high TSH due to the physiological neonatal TSH surge that elevates TSH levels and causes dynamic T4 and T3 changes in the first 1 or 2 days after birth. Early discharge of mothers postpartum has increased the ratio of false positive TSH elevations. Although transient hypothyroidism may occur frequently, all these infants should be treated as having CH for the first 3 years of life, taking into account the risk of mental retardation. A reevaluation after 3 years is needed in such patients. The goal of initial therapy in CH is to minimize neonatal central nervous system exposure to hypothyroidism by normalizing thyroid function, as rapidly as possible. © Journal of Clinical Research in Pediatric Endocrinology, Published by Galenos Publishing.
Onhon N.O.,Istanbul Science University |
Cetin M.,Istanbul Science University
IEEE Transactions on Image Processing | Year: 2012
Image formation algorithms in a variety of applications have explicit or implicit dependence on a mathematical model of the observation process. Inaccuracies in the observation model may cause various degradations and artifacts in the reconstructed images. The application of interest in this paper is synthetic aperture radar (SAR) imaging, which particularly suffers from motion-induced model errors. These types of errors result in phase errors in SAR data, which cause defocusing of the reconstructed images. Particularly focusing on imaging of fields that admit a sparse representation, we propose a sparsity-driven method for joint SAR imaging and phase error correction. Phase error correction is performed during the image formation process. The problem is set up as an optimization problem in a nonquadratic regularization-based framework. The method involves an iterative algorithm, where each iteration of which consists of consecutive steps of image formation and model error correction. Experimental results show the effectiveness of the approach for various types of phase errors, as well as the improvements that it provides over existing techniques for model error compensation in SAR. © 2011 IEEE.
Yavuz S.,Istanbul Science University
Genes and Immunity | Year: 2016
Behcet’s disease (BD) exhibits more severe disease course and higher mortality among male patients. However, underlying mechanisms of gender differences in clinical manifestations and disease severity are unclear. The aim of this study was to determine whether testosterone (T) has any role on BD pathogenesis. We studied peripheral blood mononuclear cells (PBMC) and neutrophils of BD patients and controls. Functional assay of neutrophils, cytokine measurements of culture supernatants and gene expressions on both cells were analyzed before and after T incubation. Neutrophils were significantly activated after incubation with T in only BD patients. Incubation with T caused significantly elevated interleukin (IL)-12 and IL-2 in BD. Gene expression of IL-10 was significantly downregulated after incubation with T in BD, especially in male patients. The same difference was observed in IL-10 levels in culture supernatant after T. Baseline TLR4 expression was significantly higher in BD patients compared to healthy donors (HC). Toll-like receptor (TLR) 4 expression on PBMC was significantly elevated in female BD patients. ERAP1 expressions of all patients and controls were decreased under the T effect but it differed significantly between BD vs HC. Baseline IL23R expression was higher in BD males compared with females but the difference disappeared after T. When BD patients were analyzed separately, baseline C-C motif chemokine receptor1 (CCR1), STAT4, TLR4 and KLRC4 expressions were lower in males. Despite immunosuppressive behavior in healthy subjects, T causes neutrophil hyperactivation and TH1 type immune alterations in BD patients. Our results suggest that T may have a role in BD pathogenesis by altering the expression level of IL-10, TLR4, ERAP1, CCR1.Genes and Immunity advance online publication, 28 July 2016; doi:10.1038/gene.2016.28. © 2016 Macmillan Publishers Limited, part of Springer Nature.