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
The effect of cannabidiol on cancer-pathway genes in doxorubicin-sensitive and resistant breast cancer cells
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Çifçi, Kezban Uçar; Çelik, Ayşe Büşranur; Güçlü, Ebru; Şahinoğlu, Nisanur; Gülüm, Levent; Çapkınoğlu, Emir; Tutar, Yusuf
Purpose: Cannabidiol (CBD) is a primary bioactive, non-intoxicating cannabinoid found in the cannabis plant. Studies have shown that CBD causes anticancer activity by inhibiting the expression of growth factors and inducing apoptosis, leading to cell cycle arrest. In this study, we aimed to determine how CBD influences the expression of genes that affect cancer pathways in doxorubicin-sensitive (MCF-7) and doxorubicin-resistant (MCF-7/Adr) breast cancer cells. Materials and Methods: IC50 concentrations of CBD in MCF-7 and MCF-7/Adr cell lines were determined by the MTT cell cytotoxicity assay. RNA isolation and subsequent cDNA synthesis were performed for qPCR experiments with the determined IC50 values. The effects of CBD on the cell cycle and apoptosis were studied using flow cytometry. IC50 values of CBD were determined in MCF-7 and MCF-7/Adr breast cancer cell lines at eight different concentrations and at three different incubation periods (24 h, 48 h, and 72 h) with different doses. RT-qPCR was used to investigate the molecular mechanisms underlying the expression of genes involved in cancer pathway analysis. Results: Treatment with CBD at concentrations of 17.57 μM (MCF-7) and 11.41 μM (MCF-7/Adr) for 48 h decreased colony formation, induced apoptosis, and inhibited cell invasion in both cell lines. In addition, we observed significant alterations of angiogenesis, apoptosis, cell cycle, cellular senescence, DNA damage and repair, epithelial-to-mesenchymal transition, hypoxia, metabolism, telomeres, and telomerase in both cell lines. Conclusions: Our research indicates that CBD could be an effective natural bioactive compound for breast cancer treatment, inhibiting tumor cell proliferation and inducing apoptosis.
Transcriptional reprogramming of cancer metabolism: Tricholoma terreum inhibits nucleotide biosynthesis and energy flux in MCF-7 cells by downregulating DHFR, TK1, and ENO1
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Gülüm, Levent; Güler, Emrah; Çapkınoğlu, Emir; Çelik, Ayşe Büşranur; Tutar, Yusuf
Tricholoma terreum, a mushroom rich in bioactive compounds, exhibits notable antioxidant and anticancer properties. Despite its traditional use, its effects on breast cancer metabolism remain underexplored. Here, we conducted comprehensive phytochemical and volatile organic compound profiling of T. terreum extracts and evaluated their cytotoxicity against MCF-7 breast cancer cells. Using SPME–GC–MS and HPLC, we identified a complex chemical matrix dominated by organic acids (acetic acid, 43.85%) and nitrogen-containing heterocyclics (2-acetylpyridine, 15.19%), alongside significant phenolic acids such as gallic acid and syringic acid. Biological assays indicated that the ethanol extract showed notable cytotoxic effects, reducing MCF-7 cell viability to 3.64% after 72 h, while higher viability was preserved in healthy CCD-1072sk fibroblast cells. Using cell viability assays, flow cytometry, and gene expression analysis, we found that ethanol extracts selectively reduced cancer cell viability, induced G0/G1 cell cycle arrest (71.92%), and promoted apoptosis. Mechanistically, treatment downregulated key nucleotide biosynthesis genes (DHFR, TK1) and the glycolytic enzyme gene (ENO1), while upregulating the oxidative stress response gene SLC7A11 (18.32-fold), suggesting disruption of cancer metabolic pathways. These findings reveal a metabolic reprogramming effect of T. terreum extracts, highlighting their potential as metabolism-targeted agents in breast cancer therapy. Further studies are warranted to validate these effects in vivo and isolate active constituents.
Experimental investigation of fin distribution effects on single-phase flow in micro-pin-finned heat sinks with numerical support
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Evcimen, Alperen; Markal, Burak; Avcı, Mete
Technological development and thermal management are closely related, as chip-based units demand efficient cooling. Microchannel cooling is a key solution. This study, for the first time, experimentally and numerically investigates fin distributions with decreasing numbers, with/without staggered configurations, and the effect of dimples on single-phase flow in micro-pin-finned heat sinks. The database covers mass fluxes from 500 to 750 kg m−2 s−1 (in 50 increments) and four heat sinks (coded as MH-0, MH-1, MH-2, MH-3), with Reynolds numbers ranging from 234 to 327. Complementary numerical simulations were also employed to visualize flow structures and local Nusselt distributions to elucidate the experimental observations. It was concluded that low-velocity eddies occur in the dimples and between the successive pin-fins. The best thermal performance was obtained for MH-3, while the lowest pressure drop was measured for MH-1. Therefore, if heat transfer is the primary aim, MH-3 is preferred. MH-3 increases average Nusselt Number (Nuavg) by between 11.45% and 14.38% compared to MH-0. However, the pumping power results underline the importance of MH-1. Compared to MH-0, the pumping power decreases by up to 18.4% for MH-1, 16.6% for MH-2, and 13.8% for MH-3.
An experimental study and FEM-based analysis for road safety barriers: additively manufactured PLA–geopolymer hybrid composites
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Yentimur, Muhammed Fatih; Akarsu, Oğuzhan; Alparslan, Cem; Kütük-Sert, Tuba; Bayraktar, Şenol; Aydin, Abdulkadir Cüneyt; Tortum, Ahmet
This study investigates the impact response and energy absorption performance of additively manufactured PLA–geopolymer hybrid composites for potential application in road safety barriers. Hybrid Charpy specimens were fabricated with three different infill densities (20%, 60%, and 100%), combining a 3D-printed PLA outer shell with a geopolymer core. Charpy impact tests were conducted in accordance with ISO 179-1 and ASTM D6110, and the absorbed energy, specific energy absorption, and mass efficiency were determined experimentally. A phase-based analytical model was also used to estimate elastic energy contributions, while fracture surfaces were examined to identify infill-dependent damage mechanisms. To extend the material-level findings to an engineering-scale application, the observed trends were transferred to a New Jersey-type road safety barrier model and evaluated using ANSYS Explicit Dynamics. The results showed that infill density strongly affects fracture behavior and energy dissipation performance, with 60% infill providing the most balanced response in terms of energy absorption and mass/material efficiency. The originality of the present study lies in going beyond a material-scale investigation of the impact behavior of additively manufactured PLA–geopolymer hybrid structures by integrally correlating the experimental Charpy results with a theoretical energy-based framework, fracture-surface observations, and explicit dynamic finite element analysis of a New Jersey-type road safety barrier model.
Prevalence of obstructive sleep apnea syndrome in patients with resistant hypertension
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Özyurt, Songül; Taştan, Mustafa; Gümüş, Aziz; Beyazal Polat, Hatice; Özçelik, Neslihan
Background: Obstructive sleep apnea (OSA) is a significant cardiovascular risk factor, frequently co-existing with systemic hypertension. While the association between OSA and blood pressure elevation is well documented, its specific prevalence and impact among patients with resistant hypertension remain a critical area of clinical investigation. Objective: The primary aim of this study was to evaluate the prevalence and severity of obstructive sleep apnea (OSA) specifically within a cohort of patients with resistant hypertension (RHT). Additionally, we sought to identify the clinical and anthropometric factors that distinguish RHT patients with OSA from non-resistant hypertensive and normotensive controls, thereby clarifying the increased hypoxic burden and polysomnographic differences unique to this high-risk population. Methods: A total of 300 patients presenting with OSA symptoms were included. Participants were classified into three groups: Group 0 (n = 100), normotensive individuals; Group 1 (n = 100), non-resistant hypertension; and Group 2 (n = 100), confirmed resistant hypertension. Standard overnight polysomnography (PSG) was performed on all participants. Demographic data, comorbidities, anthropometric measurements, and PSG parameters were recorded and compared across groups. Results: Of the subjects, 50.3% were female (sex), and the mean age was 49.5 ± 12.3 years. Patients with RHT (Group 2) were significantly older and had a higher prevalence of diabetes mellitus. OSA prevalence was 94% in Group 2 (37% severe), 89% in Group 1 (22% severe), and 74% in Group 0 (only 2% severe). In PSG analysis, AHI and ODI values were significantly higher in hypertensive groups (Groups 1 and 2) compared to normotensive individuals (Group 0), while minimum and mean oxygen saturations were significantly lower. Conclusions: OSA is both more prevalent and more severe in patients with resistant hypertension. Furthermore, hypertensive OSA patients are characterized by an increased hypoxic load compared to normotensives. Systematic investigation and detailed polysomnographic evaluation of OSA are of paramount importance in hypertensive individuals, particularly those with resistant hypertension.
