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Dental stem cells in bone tissue engineering: Current overview and challenges

Ercal, P. | Pekozer, G.G. | Kose, G.T.

Book Part | 2018 | Advances in Experimental Medicine and Biology1107 , pp.113 - 127

The treatment of bone that is impaired due to disease, trauma or tumor resection creates a challenge for both clinicians and researchers. Critical size bone defects are conventionally treated with autografts which are associated with risks such as donor site morbidity and limitations like donor shortage. Bone tissue engineering has become a promising area for the management of critical size bone defects by the employment of biocompatible materials and the discovery of novel stem cell sources. Mesenchymal stem cells (MSCs) can be isolated with ease from various dental tissues including dental pulp stem cells, stem cells from apical p . . .apilla, dental follicle stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, gingival stem cells and tooth germ derived stem cells. Outcomes of dental MSC mediated bone tissue engineering is explored in various in vivo and in vitro preclinical studies. However, there are still obscurities regarding the mechanisms underlying in MSC mediated bone regeneration and challenges in applications of dental stem cells. In this review, we summarized dental stem cell sources and their characterizations, along with currently used biomaterials for cell delivery and future perspectives for dental MSCs in the field of bone tissue engineering. Further efforts are necessary before moving to clinical trials for future applications. © Springer International Publishing AG 2018 Daha fazlası Daha az

Construction of Home-Made Tin Fixed-Point Cell at TUBITAK UME

Kalemci, M. | Arifovic, N. | Bağçe, A. | Aytekin, S.O. | Ince, A.T.

Article | 2015 | International Journal of Thermophysics36 ( 8 ) , pp.1968 - 1979

TUBITAK UME Temperature Laboratory initiated a new study which focuses on the construction of a tin freezing-point cell as a primary temperature standard. The design is an open-cell type similar to the National Institute of Standards and Technology design. With this aim, a brand new vacuum and filling line employing an oil diffusion pump and two cold traps (liquid nitrogen and dry ice) was set-up. The graphite parts (crucible, thermometer well, etc.) have been baked at high temperature under vacuum. Each cell was filled with approximately 1 kg of high-purity tin (99.9999 %) in a three-zone furnace. Then several melting and freezing . . .curves were obtained to assess the quality of the home-made cell, and also the new cell was compared with the existing reference cell of the laboratory. The results obtained are very close to the reference cell of UME, indicating that the method used for fabrication was promising and satisfactory and also seems to meet the requirements to have a primary level temperature standard. © 2015, Springer Science+Business Media New York Daha fazlası Daha az

Evaluation of Sexual Dysfunction in Males with Diabetes

Yıldız, H. | Bölüktaş, R.P.

Article | 2015 | Sexuality and Disability33 ( 2 ) , pp.187 - 205

This study was conducted in order to determine the prevalence of sexual dysfunction and factors affecting sexual dysfunction (SD) in male patients with diabetes. Diabetes is a public health problem. Erectile dysfunction (ED) is seen in nearly half of all males who have had diabetes for more than 10 years. Erectile dysfunction, metabolic and psychological factors are involved in the emergence. A descriptive was conducted and questionnaire was used in this study. Data was gathered via general knowledge form which consists of socio-demographic characteristics and risk factors, International Index of Erectile Function, Quality of Life S . . .cale (SF-36), Beck Depression Inventory, Coopersmith Self-Esteem Scale, and Body Image Scale. SD was determined in 48 % of our cases. The most affected domain among the cases was erectile function (33.1 %) and intercourse satisfaction (29.1 %), and the least affected domain was sexual desire (6.3 %). Most of the male cases with ED had mild and moderate ED (42.6 %). Factors affecting SD’s included age, education level, obesity, hypertension, retinopathy, vasculopathy, nephropathy, diabetic foot, HBA1C and LDL levels, diabetes duration, drugs used. All quality of life subgroups scores were lower in male patients with SD than patients without SD except for pain. Depression and body image scores were lower in male patients with SD. SD’s are affected by both metabolic and psychosocial factors. Sexual dysfunction in men with diabetes should be routinely evaluated. © 2015, Springer Science+Business Media New York Daha fazlası Daha az

Efficient simulations for a Bernoulli mixture model of portfolio credit risk

Başoğlu, İ. | Hörmann, W. | Sak, H.

Article | 2018 | Annals of Operations Research260 ( 01.02.2020 ) , pp.113 - 128

We consider the problem of calculating tail loss probability and conditional excess for the Bernoulli mixture model of credit risk. This is an important problem as all credit risk models proposed in literature can be represented as Bernoulli mixture models. Thus, we deviate from the efficient simulation of credit risk literature in that we propose an efficient simulation algorithm for this general Bernoulli mixture model in contrast to previous works that focus on specific credit risk models like CreditRisk+ or Credit Metrics. The algorithm we propose is a combination of stratification, importance sampling based on cross-entropy, an . . .d inner replications using the geometric shortcut method. We evaluate the efficiency of our general method considering three different examples: CreditRisk+ and two of the latent variable models, the Gaussian and the t-copula model. Numerical results suggest that the proposed general algorithm is more efficient than the benchmark methods for these specific models. © 2016, Springer Science+Business Media New York Daha fazlası Daha az

Some determinants of life expectancy in the United States: results from cointegration tests under structural breaks

Ketenci, N. | Murthy, V.N.R.

Article | 2018 | Journal of Economics and Finance42 ( 3 ) , pp.508 - 525

In the United States, health economists, experts in population studies, and policy makers seek to understand the important factors that augment life expectancy. This paper attempts to identify empirically effects of some major determinants on life expectancy in the United States during the period 1960–2012. Recently developed powerful methods of unit root testing and cointegration analysis, Carrion-i-Silvestre et al. Economet Theor, 25, 1754–1792, (2009), Perron and Yabu J Bus Econ Stat, 27, 369–96, (2009), Kejriwal and Perron J Econ, 146(1), 59–73, (2008), Kejriwal and Perron J Bus Econ Stat, 28(4), 503–522, (2010a), and Maki Econ . . .Model, 29(5), 2011–2015, (2012) that allow for the presence of structural shifts, are employed. The papers’ findings reveal that the level of real per capita income and the level of educational attainment are the factors that affect the level of life expectancy most. Other factors such as the level of real health expenditure per capita and any measure of income inequality, although important, were found to be highly collinear with real per capita income. The policy implications of the results of the paper are discussed. © 2017, Springer Science+Business Media New York Daha fazlası Daha az

Ultrasonic Investigation of the Effect of Carbon Content in Carbon Steels on Bulk Residual Stress

Uzun, F. | Bilge, A.N.

Article | 2015 | Journal of Nondestructive Evaluation34 ( 2 ) , pp.508 - 525

Formation of residual stress as a result of welding process is a familiar fact, but its relation with material composition is unknown. This study aims to investigate the effect of carbon content on welding residual stress in carbon steels. For this purpose, samples of ultra-low carbon interstitial free, low carbon and medium carbon steels are selected. Welding is performed as a beam on plate in spite of a joining process. Weld grooves are prepared at center of the rectangular samples. Automated submerged arc technique is preferred for welding process in order to ensure same welding parameters at each sample. Ultrasonic sound waves a . . .re used to determine residual stress. This non-destructive technique provides bulk residual stress which is average of shear and normal stresses through thickness of a material. A new approach is practiced to verify experimentally determined bulk residual stress with finite element simulation results. The model geometry of numerical analysis is divided into equivalent parts and average of shear and normal stresses is calculated. Non-destructive ultrasonic technique seems to be in good agreement with finite element analysis. © 2015, Springer Science+Business Media New York Daha fazlası Daha az

Cytoglobin inhibits migration through PI3K/AKT/mTOR pathway in fibroblast cells

Demirci, S. | Doğan, A. | Apdik, H. | Tuysuz, E.C. | Gulluoglu, S. | Bayrak, O.F. | Şahin, Fikrettin

Article | 2018 | Molecular and Cellular Biochemistry437 ( 01.02.2020 ) , pp.133 - 142

Cell proliferation and migration are crucial in many physiological processes including development, cancer, tissue repair, and wound healing. Cell migration is regulated by several signaling molecules. Identification of genes related to cell migration is required to understand molecular mechanism of non-healing chronic wounds which is a major concern in clinics. In the current study, the role of cytoglobin (CYGB) gene in fıbroblast cell migration and proliferation was described. L929 mouse fibroblast cells were transduced with lentiviral particles for CYGB and GFP, and analyzed for cell proliferation and migration ability. Fibroblas . . .t cells overexpressing CYGB displayed decreased cell proliferation, colony formation capacity, and cell migration. Phosphorylation levels of mTOR and two downstream effectors S6 and 4E-BP1 which take part in PI3K/AKT/mTOR signaling declined in CYGB-overexpressing cells. Microarray analysis indicated that CYGB overexpression leads to downregulation of cell proliferation, migration, and tumor growth associated genes in L929 cell line. This study demonstrated the role of CYGB in fibroblast cell motility and proliferation. CYGB could be a promising candidate for further studies as a potential target for diseases related to cell migration such as cancer and chronic wound treatment. © 2017, Springer Science+Business Media, LLC Daha fazlası Daha az

Management of blood donation system: Literature review and research perspectives

Baş, S. | Carello, G. | Lanzarone, E. | Ocak, Z. | Yalçındağ, S.

Conference Object | 2016 | Springer Proceedings in Mathematics and Statistics169 , pp.121 - 132

2nd International Conference on Health Care Systems Engineering, HCSE 2015 -- 27 May 2015 through 29 May 2015 -- -- 181519

Evidence for an association of serum melatonin concentrations with recognition and circadian preferences in patients with schizophrenia

Sahbaz, C. | Özer, O.F. | Kurtulmus, A. | Kırpınar, I. | Şahin, Fikrettin | Guloksuz, S.

Article | 2019 | Metabolic Brain Disease34 ( 3 ) , pp.865 - 874

Melatonin, a neuro-differentiation factor, may play a role in the neurodevelopmental origins of schizophrenia. Cognitive impairment and decreased melatonin are reported in schizophrenia; however, the relationship between them remains unclear. We hypothesised that patients with schizophrenia would have lower concentrations of circulating melatonin than healthy controls and that melatonin levels would be associated with cognitive impairment. This study included 47 patients with schizophrenia and 40 healthy controls (HC). Serum melatonin concentrations were measured using the enzyme-linked immunosorbent assay. Positive and Negative Syn . . .drome Scales (PANSS), The Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI), the Stroop and Oktem verbal memory processes (VMPT) tests were applied. Patients with schizophrenia had lower levels of melatonin compared to the HC group (p = 0.016), also after controlling for age, sex, and body mass index (BMI) (p = 0.024). In patients with schizophrenia, melatonin concentrations were associated with higher BMI (rho = 0.34, p = 0.01) and lower MEQ score (rho = -0.29, p = 0.035). The patient sample was split into low and high melatonin categories by using the median melatonin concentration in HC as the cut-off. Patients in the low melatonin group had poorer performance in VMPT-Recognition (p = 0.026) and Stroop-Colour Error (p = 0.032). Notwithstanding its limitations, the findings of this exploratory study suggest that decreased serum melatonin concentrations observed in schizophrenia might also be associated with cognitive impairment and circadian preferences. Future studies are required to investigate the role of melatonergic pathways in patients with schizophrenia. © 2019, Springer Science+Business Media, LLC, part of Springer Nature Daha fazlası Daha az

Psychological Help-Seeking Attitudes and Barriers to Help-Seeking in Young People in Turkey

Koydemir, S. | Erel, O. | Yumurtacı, D. | Şahin, G.N.

Article | 2010 | International Journal for the Advancement of Counselling32 ( 4 ) , pp.274 - 289

This qualitative research sought to understand the needs of Turkish university students related to adjustment to university, the sources they seek help from, their attitudes about and barriers to psychological help-seeking. Data analysis of interview transcriptions from 15 undergraduates identified several themes. Interpersonal problems, difficulties with staff and authority and future concerns were the most frequent issues. Students preferred informal sources of help in dealing with problems and in the main did not seek psychological help when confronted with problems. Perceiving one's problems as manageable and having an unwilling . . .ness to disclose oneself to others were among the barriers to help-seeking. Students were also unwilling to seek help from a professional unless the problem seemed crucial. © 2010 Springer Science+Business Media, LLC Daha fazlası Daha az

Boron promotes streptozotocin-induced diabetic wound healing: roles in cell proliferation and migration, growth factor expression, and inflammation

Demirci, S. | Doğan, A. | Aydın, S. | Dülger, E.Ç. | Şahin, Fikrettin

Article | 2016 | Molecular and Cellular Biochemistry417 ( 01.02.2020 ) , pp.119 - 133

Acute wounds do not generally require professional treatment modalities and heal in a predictable fashion, but chronic wounds are mainly accompanied with infection and prolonged inflammation, leading to healing impairments and continuous tissue degradation. Although a vast amount of products have been introduced in the market, claiming to provide a better optimization of local and systemic conditions of patients, they do not meet the expectations due to being expensive and not easily accessible, requiring wound care facilities, having patient-specific response, low efficiency, and severe side-effects. In this sense, developing new, . . .safe, self-applicable, effective, and cheap wound care products with broad-range antimicrobial activity is still an attractive area of international research. In the present work, boron derivatives [boric acid and sodium pentaborate pentahydrate (NaB)] were evaluated for their antimicrobial activity, proliferation, migratory, angiogenesis, gene, and growth factor expression promoting effects on dermal cells in vitro. In addition, boron-containing hydrogel formulation was examined for its wound healing promoting potential using full-thickness wound model in streptozotocin-induced diabetic rats. The results revealed that while both boron compounds significantly increased proliferation, migration, vital growth factor, and gene expression levels of dermal cells along with displaying remarkable antimicrobial effects against bacteria, yeast, and fungi, NaB displayed greater antimicrobial properties as well as gene and growth factor expression inductive effects. Animal studies proved that NaB-containing gel formulation enhanced wound healing rate of diabetic animals and histopathological scores. Overall data suggest a potential promising therapeutic option for the management of chronic wounds but further studies are highly warranted to determine signaling pathways and target metabolisms in which boron is involved to elucidate the limitations and extend its use in clinics. © 2016, Springer Science+Business Media New York Daha fazlası Daha az

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