Ramazan Erdem

Electrospinning of single and multilayered scaffolds for tissue engineering applications

Abstract Optimized electrospinning conditions were applied to produce single and multilayered (ML) scaffolds composed of polycaprolactone, collagen and elastin. The ML scaffold was cross-linked with glutaraldehyde to increase the stability. Morphological and structural characteristics of the scaffolds were measured by SEM and FTIR analyses. Results revealed that polymers combined to each other well and uniform fibers were obtained with the diameters ranging from 156 ± 53 to 1536 ± 293 nm. Contact angle measurements were performed to investigate the hydrophilic character of each structure. It was observed that incorporation of the natural polymers into the blends increased the hydrophilicity. Mechanical tests proved that collagen contributed to fabricate stiffer structures while elastin provided more elasticity. Biocompatibility of the scaffolds was examined by SEM analysis and WST-1 test with mouse fibroblast cells (L929) in vitro. Results exhibited that the addition of natural polymers increased the cell growth, and none of the single and ML scaffolds presented cytotoxic effect.

Langerhans Cell Histiocytosis: A Diagnostic Challenge in the Oral Cavity

Background Langerhans cell histiocytosis (LCH) is a rare disorder of the reticuloendothelial system with unknown etiology. This report aims to present a case of LCH with diffuse involvement of the oral cavity and to raise awareness of the distinguishing features of this diagnostically challenging entity. Case Report A 26-year-old male patient presented with complaints of teeth mobility, intense pain, and difficulty in chewing. Intraoral and radiological examinations revealed generalized gingival hyperplasia and severe teeth mobility with widespread alveolar bone loss. Periodontal therapy was performed with no significant improvement. An incisional biopsy revealed Langerhans cells and positive reaction to S-100 and CD1, and the patient was diagnosed with LCH. The patient underwent systemic chemotherapy with vinca alkaloids and corticosteroids. Regression of gingival lesions, as well as significant decrease in mobility of the remaining teeth and severity of pain, was achieved during 12 months of follow-up. Conclusion The rarity and variable system involvement of LCH necessitate a multidisciplinary approach be carried out for accurate diagnosis, effective treatment, and an uneventful follow-up. Awareness of oral manifestations of LCH may aid clinicians greatly in reducing morbidity and mortality associated with this debilitating condition.

C-MYC and BCL2 translocation frequency in diffuse large B-cell lymphomas: A study of 97 patients.

Purpose: Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma with marked biologic heterogeneity. MYC and BCL2 rearrangements have been reported in a proportion of DLBCLs, where they may be associated with an adverse clinical outcome. The aim of this study was to determine the frequency of MYC and BCL2 translocations in DLBCL and assess the prognostic impact in DLBCL patients. Materials and Methods:   In the present study, we evaluated the expression patterns of CD 10, BCL6, and MUM 1 by immunohistochemistry in 121 cases with DLBCL in tissue microarray (TMA): 62 cases in germinal center B-cells (GCBs); and 59 cases in activated B-cells (ABCs) of which 60 were females and 61 were males. MYC and BCL2 rearrangements were investigated by interphase fluorescence in situ hybridization on TMAs in 97 DLBCLs. Result: MYC rearrangements were observed in 11 of 97 cases. There was no association with other clinical features, including age, sex, and nodal/extranodal disease. MYC rearrangement was associated with significantly worse overall survival (P < 0.01). BCL2 rearrangements were observed in 14 of 97 cases. There was no association with other clinical features including age and sex. BCL2 rearrangement had a worse outcome (P < 0.01). MYC and BCL2 rearrangements were observed in 3 of 97 cases with the age of  53 (female), 53, 63 years old, respectively, died in 24, 18, and 35 months after the diagnosis. Two cases had primary nodal and one case primary extranodal presentations. All these patients had stage IV disease. Conclusion: We concluded that C-MYC and BCL2 may contribute to aggressive transformation, and more mechanism-based therapy should be explored. Targeted therapies involving these rearrangements and its associated pathways may change the fate of DLBCLs. Analysis of MYC gene rearrangement along with BCL2 is critical in the identification of high-risk patients with poor prognosis.

Evaluation of electromagnetic shielding effectiveness of multi-axial fabrics and their reinforced PES composites

The usage of electrical and electronic equipments has been increasing in daily life, which has a potential hazardous impact on humans and other living organisms. In this paper, multi-axial fabrics containing steel yarns and carbon filaments, and their polyester (PES) resin-reinforced composites have been prepared for electromagnetic shielding applications. The electromagnetic shielding effectiveness (EMSE) of these structures was determined by using coaxial transmission line measurement technique. There were eight different multi-axial fabrics constructed. It was observed that the amount and the orientation of carbon and stainless steel yarns influenced the EMSE performances of multi-axial fabrics and their reinforced PES composites. The structures containing both carbon filaments and stainless steel yarns exhibited better EMSE than the ones including only one type of conductive yarns or filaments. Also, the EMSE performance of multi-axial fabrics was found better than their reinforced composites. The best EMSE results were obtained for the fabric, including two layers of yarns (steel and carbon) on top of each other in the centre with the angle of 45 and −45°.

Analyses of the mechanical, electrical and electromagnetic shielding properties of thermoplastic composites doped with conductive nanofillers

The purpose of this study is to observe effect of incorporating vapor-grown carbon nanofibers with various amounts in polyvinylidene fluoride matrix in terms of mechanical strength and electromagnetic shielding effectiveness. Thermoplastic conductive nanocomposites were prepared by heat-pressed compression molding. Vapor-grown carbon nanofibers were utilized at various weight ratios (1 wt.%, 3 wt.%, 5 wt.%, and 8 wt.%) as conductive and reinforcing materials. Polyvinylidene fluoride was used as a thermoplastic polymer matrix. Scanning electron microscopic analysis was conducted in order to characterize the morphology and structural properties of the nanocomposites and results revealed well dispersion of carbon nanofibers within the matrix for all concentrations. Mechanical characteristics were investigated according to standards. Findings proved that overall increments of 16%, 37.5%, and 56% were achieved in terms of tensile strength, elasticity modulus, and impact energy, respectively, where a total reduction of 44.8% was observed in terms of elongation for 8 wt.% vapor-grown nanofiber matrix compared to that of 0 wt.%. Electromagnetic shielding effectivenesses of the nanocomposites were determined by standard protocol using coaxial transmission line measurement technique in the frequency range of 15–3000 MHz. It was observed that resistance, sheet resistance, and resistivity of nanocomposites depicted substantial reduction with the increment in nanofiber content. Nevertheless, it was observed that nanofiber content, dispersion, and network formation within the composites were highly influent on the electromagnetic shielding effectiveness performance of the structures.

Elektrik Alan ile Lif Çekimi Yöntemi ile Elde Edilen Ligand Katkılı Poliüretan Nanoliflerin Morfolojik ve Lüminesans Özelliklerinin İncelenmesi

Luminesans ozellige sahip binaftilamin ligand sentezi gerceklestirilmis ve diklorometan/hekzan karisiminda kristallendirilmistir. Bu yapilarin elemental karakterizasyonunda fourier transform infrared spectroscopy (FTIR) ve nukleer manyetik rezonans (H-NMR) spektrumlarindan yararlanilmistir. Sentezlenen ligand, elektrik alan ile lif cekimi yontemi ile poliuretan nanolifler icerisine katkilanmistir. Bu liflerden meydana gelen nano ag yuzeylerin morfolojik analizleri taramali elektron mikroskobunda (SEM) incelenmistir. Caplari ortalama 730±322 nm ile 858±307 nm araliginda degisen hatasiz liflerin elde edildigi gorulmustur. Yapilan florimetri analizleri sonucunda, ligand katkili liflerin yaklasik olarak 530 nm civarinda emisyon verdigi ve luminesans ozellik sergiledigi tespit edilmistir.