Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Mandibular bone apposition in relation to temporomandibular joint disorders: a radiographic and MRI study
(BioMed Central, 2026) Akçay Köprücü, Saliha; Atasoy Sındıraç, Aysun; Uzun, Tuğçenur; Günaçar, Dilara Nil
Background: This study investigated whether mandibular angle bone apposition (MABA) observed in temporomandibular disorder (TMD) patients reflects intrinsic joint pathology or represents a skeletal response to altered biomechanical loading related to occlusal and demographic factors.
Methods: Panoramic radiographs and temporomandibular joint (TMJ) magnetic resonance imaging (MRI) scans from 282 patients with TMDss (564 TMJs) were retrospectively analyzed. Bone apposition was graded on panoramic images, while MRI findings (disc position, condylar morphology, effusion) were recorded. Demographic data and individual tooth loss patterns were evaluated. Statistical analyses included chi-square tests with Bonferroni-adjusted post hoc comparisons and ordinal logistic regression based on generalized estimating equations.
Results: MABA showed no significant association with MRI-detected intra-articular TMJ abnormalities (p > 0.05). In univariate analyses, higher apposition levels were associated with increasing age, male sex, and greater numbers of missing maxillary and mandibular teeth (p ≤ 0.05). Tooth-level analysis demonstrated a localized association involving the right maxillary second premolar (p = 0.037). In multivariable analysis using generalized estimating equations, male sex, right-side location, and higher grades of joint effusion remained significantly associated with bone apposition levels (p ≤ 0.05).
Conclusions: Although a causal relationship cannot be confirmed in this retrospective design, the observed associations suggest that MABA may be more closely related to functional and demographic factors than to intra-articular TMJ pathology. When MABA is detected on panoramic radiographs, assessment of occlusal stability may be considered, as functional loading patterns could play a role in mandibular remodeling.
Investigation of FGM patch repairs for cracked aluminum structures: J-integral analysis
(Nature Publishing Group, 2026) Abdelmadjid, Moulgada; Abderahmane, Sahli; Zagane Mohammed El Sallah; Ahmed, Mordjani; Tahar, Adjoudj; Kurt, Zafer; Yaylacı, Ecren Uzun; Yaylacı, Murat
Functionally Graded Materials (FGMs) represent a highly advanced solution for the repair of cracked aircraft structures, offering superior performance compared to conventional homogeneous materials. FGMs contribute to more durable, lightweight, and structurally effective repairs, extending service life while maintaining safety and performance standards. This study investigates the effectiveness of functionally graded material (FGM) patches for reinforcing cracked aluminum alloy plates. Using three-dimensional finite element analysis implemented in ABAQUS with a USDFLD subroutine, spatial variations of the Young's modulus were applied according to linear, logarithmic, and exponential gradation laws. The fracture behavior was quantified through J-integral calculations under plane strain conditions. Results show that FGM patches significantly reduce the J-integral at the crack tip compared to unrepaired plates: up to 56% reduction for linear gradation, 52% for logarithmic, and 44% for exponential gradation. Linear gradation is most effective in mitigating longitudinal crack propagation, while logarithmic gradation efficiently reduces local principal stresses. Contour convergence and comparison with homogeneous patch and unrepaired plate benchmarks confirm the reliability of the numerical results. These findings provide mechanistic insight into stiffness-gradient-driven stress redistribution, guiding the optimal design of FGM repairs for enhanced durability.
Whole-genome characterization of clinical Enterococcus faecalis and Staphylococcus epidermidis Isolates reveals mecA-positive E. faecalis and a shared lnu(A)-rep7a resistance plasmid in Türkiye
(BioMed Central, 2026) Ejder, Nebahat; Düzgün, Azer Özad
Background: This study aimed to genomically characterize clinical Enterococcus faecalis and Staphylococcus epidermidis isolates obtained from aspirate and sputum samples at Bayburt State Hospital, focusing on antimicrobial resistance genes, virulence factors, and mobile genetic elements.
Methods: Whole-genome sequencing (WGS) was performed on the isolates, and antimicrobial resistance genes, virulence determinants, multilocus sequence types (MLST), plasmid replicons, and mobile genetic elements were identified using bioinformatics tools.
Results: The E. faecalis E5 (ST64) isolate, recovered from an aspirate sample, carried multiple antimicrobial resistance genes, including mecA, vanT, erm(B), tet(M), and qacA, along with a diverse virulence gene repertoire (cyl, ebp, ace, and agg), mobile genetic elements (Tn6009, ISL1a3), and four plasmid replicons (rep19C, rep9C, repUS43, and rep7a). The E. faecalis E184 and E187 isolates (ST124), obtained from sputum samples, harbored fewer acquired resistance genes but shared gyrA (T672A) and parC (V307I) mutations associated with fluoroquinolone resistance. The S. epidermidis ST59 isolate carried resistance genes lnu(A), fosB, and qacD, together with the plasmid replicon rep7a and insertion sequence ISSau4. The co-occurrence of lnu(A) and the rep7a plasmid in both species suggests a potential pathway for interspecies transmission of resistance determinants.
Conclusions: This study reports the genomic detection of mecA in an E. faecalis isolate from Türkiye based on WGS analysis. However, this finding is based solely on genomic data and lacks phenotypic or experimental validation. The detection of a shared plasmid-associated resistance element (lnu(A)-rep7a) in both E. faecalis and S. epidermidis highlights the potential for interspecies resistance gene flow within the hospital environment.
Stress distribution in angulated bendable one-piece and two-piece implant-supported single crowns in the posterior maxilla: a finite element analysis
(BioMed Central, 2026) Jaghoub, Qassam; Yeşil, Çağla; Yeşil, Zeynep
Background: This finite element analysis compared stress distribution and displacement in the implant-crown complex and peri-implant bone between angulated bendable one-piece and two-piece implants supporting posterior maxillary single crowns under standardized modeling conditions.
Methods: A three-dimensional finite element model of a maxillary first molar single crown in Misch bone density category 3 was generated. Two base models representing a bendable one-piece implant and a two-piece angulated implant system (15°, 4.1 × 11.5 mm) were each evaluated with 2 crown materials (monolithic zirconia and lithium disilicate) and a 0.05-mm cement layer. The bendable one-piece implant was analyzed in its final post-adjustment geometry. All component interfaces were defined as idealized bonded contacts, and a 100-N oblique load at 30° was applied to the occlusal surface in a linear static analysis.
Results: Implant von Mises stresses were markedly higher in the bendable one-piece models (518-529 MPa) than in the two-piece angulated models (109-112 MPa), representing an approximately 4.7-times-higher stress level. Cement-layer stresses ranged from 22 to 29 MPa and were higher in the two-piece configurations. Crown displacement was approximately two times higher in the two-piece configurations (0.036-0.037 mm) than in the one-piece configurations (0.018 mm). Peri-implant bone principal stresses were also higher in the one-piece models, whereas differences between zirconia and lithium disilicate crowns were modest.
Conclusions: Within the limitations of this finite element analysis, the two-piece angulated configuration was associated with lower implant and peri-implant bone stresses than the bendable one-piece configuration, although it showed higher cement-layer stress and crown displacement. These results represent comparative behavior within an idealized model.
High TROP-2 expression as a predictor of poor neoadjuvant chemotherapy response in luminal B breast cancer: a retrospective clinicopathological study
(BioMed Central, 2026) Öztürk, Çiğdem; Çubukçu, Safiye Sümeyye; Şen, Bayram; Öztürk, Ahmet Emin; Okcu, Oğuzhan
Purpose: Trophoblast cell surface antigen 2 (TROP-2) is a type I transmembrane glycoprotein that is expressed on the cell surface. It is overexpressed in various epithelial malignancies. Due to its protumoral biological effects and its role as a target receptor for antibody-drug conjugates, TROP-2 is of particular clinical interest. This study aims to investigate the relationships between TROP-2 expression, clinicopathological parameters, and response to neoadjuvant chemotherapy in invasive breast carcinomas.
Methods: TROP-2 expression was evaluated by immunohistochemically from 211 cases of invasive breast carcinoma. The H-score was used in the TROP-2 assessment. Cases with a score of 0-200 were considered low, and cases with a score above 200 were considered high TROP-2 expression.
Results: High TROP-2 expression was significantly associated with HER2 negativity (p = 0.019), lymph node metastasis (p = 0.016), and a poor response to neoadjuvant chemotherapy (RCB-II/III) (p = 0.01). Multivariate analysis revealed that molecular subtype, stromal tumor-infiltrating lymphocytes, and high TROP-2 expression were independent predictors of neoadjuvant chemotherapy response.
Conclusion: High TROP-2 expression was found to be associated with adverse clinicopathological parameters and poor response to neoadjuvant chemotherapy, and was identified as an independent predictive biomarker for neoadjuvant response. The lower pathological complete response rates observed in luminal B molecular subtype breast carcinomas with high TROP-2 expression suggest that TROP-2-targeting agents should be investigated more thoroughly in the neoadjuvant therapy setting, particularly in LB subtype cases. Furthermore, assessing TROP-2 expression in each case will aid in optimal patient selection for treatment and contribute to the personalization of oncological therapy.
