TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14365/4
Browse
6 results
Search Results
Article Model-Based Feature Selection Using Structural Equation Modeling for Enhanced Classification Performance in High-Dimensional Datasets(Gazi University, 2025-09-01) Albayrak, Muammer; Turhan, KemalFeature selection is becoming more and more important for machine learning and data mining. Especially for high dimensional datasets, it is necessary to filter out irrelevant and unnecessary features to overcome the problems of overfitting and multidimensionality. We hypothesized that an effective feature selection can be made with a model-based approach using the Structural Equation Modeling (SEM) method. The dataset consists of 2969 samples and 117 features. First, a measurement model created was tested with confirmatory factor analysis (CFA) and the number of features was reduced to 58 by removing the statistically insignificant features. In SEM analysis, sub-feature sets consisting of 55, 52, 41 and 35 features were obtained by removing the variables whose relationship was below the threshold values determined for the standardized regression coefficient (SRC). The obtained sub-feature sets were tested with a multilayer perceptron (MLP) and their effect on performance was examined. Results were compared with random forest feature importance as baseline method. SEM and random forest have generally performed very closely. While sub-feature sets created with the random forest in two-class classification produced better results, the sub-feature sets created with the suggested SEM-based method in three and five-class classification provided better performance. These results showed that effective feature selection can be made with the proposed model-based approach using SEM. With this approach, it is possible to obtain sub-feature sets that form a model which statistically significant and consistent with field knowledge by including expert knowledge in the modeling process.Article Preantral Follicle Morphometry and Ultrastructure of Antral Follicles in Anatolian Water Buffalo(TUBITAK, 2023-10-17) Bakı, Acar, D.; Bırdane, M.K.; Tokyol, Ç.; Göçmen, Karabekır, N.N.; Hayran, Mürvet; Özenç, E.; Aktepe, F.; Uçar, Mehmet; Hayran, Hatice Mürvet; Göçmen Karabekır, Nermin Nüket; Bakı Acar, Duygu; Karabekir, Nermin Nuket Gocmen; Yağcı, İlknur Pir; Yazıcı, Ebubekir; Mas, Nuket Gocmen; Acar, Duygu BakiThis study aimed to evaluate quantitative and morphometric analyses of preantral follicles and the ultrastructural characteristics of antral follicles in different oestrous cycle stages in Anatolian water buffaloes. Twenty-four ovaries collected from twelve slaughtered Anatolian water buffaloes were classified macroscopically as luteal or follicular stages. The ovaries were prepared for histological examination (Hematoxylin-eosin staining), and primordial, primary, and secondary follicle numbers were calculated, and the diameters of oocytes, follicles, and nuclei were measured under a light microscope with a micrometre. The theca and granulosa cells of antral follicles were observed under a transmission electron microscope. The mean number of preantral follicles was 18584 ± 4855, and there was a significant difference in the number of primordial follicles (p < 0.0001) and primary follicles (p < 0.001) between buffaloes. The number of primordial follicles was 10,636, that of primary follicles was 6514, and that of secondary follicles was 1434; the statistical difference was found between primordial, primary, and secondary follicle and oocyte diameters (p < 0.001) in Anatolian water buffaloes. In this study, the ultrastructural evaluation of antral follicles showed that the theca cells were active in the luteal stage with their functional organelles and higher lipid droplets. The granulosa cells were still inactive in the luteal stage. In the follicular stage of the oestrous cycle, the theca cells were found inactive, although granulosa cells showed moderate or high activity. It was found that the serum progesterone concentration and cycle stage directly affected the theca and granulosa cell ultrastructural activity in Anatolian water buffalo. In this research, information from light and electron microscopic analyses of preantral and antral follicles has been obtained for the first time for Anatolian water buffaloes. The result of our study suggests that detailed molecular research is needed to evaluate the ultrastructural activity of antral follicles in different oestrous cycle stages and steroidogenic circumstances. © TÜBİTAK.Article Citation - WoS: 1Citation - Scopus: 1Healthcare-Related Hcv Genotype 4d Infections in Kayseri, Turkey(Aves, 2022-11-15) Gokahmetoglu, Selma; Polat, Ceylan; Atalay, Mustafa Altay; Sezgin, Gulten Can; Ergor, Gul; Aygen, Bilgehan; Gursoy, Sebnem; Abacıoğlu, Yusuf Hakan; Gökahmetolu, Selma; Abacolu, Yusuf Hakan; Abacioglu, HakanBackground: The frequency of genotype 4 hepatitis C virus infection is significantly higher in a city compared to other provinces in Turkey. In this study, we aimed to investigate the epidemiology and risk factors of hepatitis C virus genotype 4 infection in Kayseri province of Turkey. Methods: A case-control study was conducted with 61 hepatitis C virus genotype 4-infected patients and 71 controls. A questionnaire was administered to the patients and controls, asking for information about the risk factors of hepatitis C virus transmission. Core/E1 and NS5B regions of hepatitis C virus genome were amplified and sequenced by Sanger method. Phylogenetic analysis and molecular clock analysis were performed. The risk was determined by calculating the odds ratio and 95% CI. Logistic regression analysis was performed to determine the effect of risk factors by controlling for confounding variables. Results: Kayseri isolates were closely related to type 4d sequences but formed a separate cluster. According to the molecular clock analysis, hepatitis C virus genotype 4d entered Kayseri province probably between 1941 and 1988. Blood transfusion and surgical intervention were found to be significant risk factors for the infection. Conclusion: Epidemiological data showed that hepatitis C virus genotype 4d infections are significantly associated with unsafe medical procedures.Article Citation - WoS: 15Citation - Scopus: 14Changes on Hepatitis C Virus Genotype Distribution in Western Turkey: Evaluation of Twelve-Year Data(Aves, 2020-02-15) Duran, Alev Cetin; Cetinkaya, Ozgul Kaya; Sayiner, Ayca Arzu; Seydaoglu, Gulsah; Ozkaratas, Emre; Abacioglu, HakanBackground/Aims: Hepatitis C virus (HCV) prevalence is 1% in Turkey with genotype 1 being the predominant type traditionally. However unique geographical location of Turkey and increasing human migration in the region influences the epidemiology of the infection. The aim of this study was to determine the changes in distribution of HCV genotypes and risk factors. Materials and Methods: In this retrospective single-center study, HCV genotyping results of 558 patients were evaluated in between 2005 and 2016.Three different HCV genotyping assays were used during the 12-year study period;restriction fragment length polymorphism (RFLP), Abbott Real Time HCV Genotype II and Bosphore HCV genotyping kit. Results: The most prevalent HCV genotype was genotype 1 detected in 88.4% of the patients followed by genotype 3 (5.2%),genotype 4 (2.9%),genotype 2 (2.1%), mixed genotypes (1.1%) and genotype 5 (0.3%). Genotype 1a showed an increasing prevalence. There were 19 patients (3.4%) either of foreign nationalities or Turkish citizens living abroad. Genotype 3 was the most common type among these patients which 10.3% had intravenous drug use history. Syrian migrant population differed in terms of HCV genotypes. Genotype 5 detected in two Syrian patients, which is the first report of HCV type 5 in Western Turkey. Among the HCV genotype 4 infected patients, 31.3% were Syrians. Conclusion: Our study showed that although genotype 1b dominance continues, the distribution and prevalence of HCV genotypes are changing in our region mainly due to migration and increase in the frequency of patients with non-traditional risk factors such as intravenous drug use. Monitoring the epidemiology of HCV genotypes may provide guidance in treatment decisions.Article A Preliminary Study of Possible Fibrotic Role of Meprin Metalloproteases in Scleroderma Patients(Turkish League Against Rheumatism, 2021-12-31) Kocak, Ayse; Avsar, Aydan Koken; Harmancı, Duygu; Akdogan, Gul; Birlik, A. MerihObjectives: This study aims to investigate the possible fibrotic role of meprin metalloproteases and possible fibrotic effects of activator protein-1 (AP-1) in scleroderma patients. Patients and methods: Between April 2018 and April 2019, a total of 85 scleroderma patients (9 males, 76 females; mean age: 54.9 +/- 12.1 years; range, 22 to 80 years) who met the 2013 American College of Rheumatology/European League Against Rheumatism criteria and 80 healthy control individuals (10 males, 70 females; mean age 42.9 +/- 10.2 years; range, 19 to 65 years) were included. Patients' data and blood samples were collected. Messenger ribonucleic acid expressions of interleukin (IL)-6, AP-1 subunits, and tumor necrosis factor-alpha (TNF-alpha) were analyzed by quantitative real-time polymerase chain reaction. Serum meprin alpha and beta protein levels were analyzed using the enzyme-linked immunosorbent assay. Results: Meprin alpha and meprin beta protein levels increased in scleroderma patients. The AP-1 subunits (c-Fos, c-Jun), IL-6, and TNF-alpha increased in scleroderma patients, compared to controls. Conclusion: Our results provide evidence showing that increased meprins levels may be related to AP-1 levels and increased meprins levels may responsible for increased inflammatory TNF-alpha and IL-6 levels. All these data suggest meprins as promising therapeutic targets to restore the balance between inflammation and extracellular matrix deposition in scleroderma.Article Citation - WoS: 7An in Vitro Study in Which New Boron Derivatives Maybe an Option for Breast Cancer Treatment(Kare Publ, 2019) Simsek, Fatma; Inan, Sevinc; Korkmaz, MehmetObjectives: We aimed to investigate the distribution of immunoreactivities of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), and inducible NOS (iNOS) on breast cancer cells in response to treatment with boron derivatives. Methods: We initially analyzed the cytotoxic effect and IC50 value of boron by MTT assay. For the evaluation of the angiogenesis, expression level of antibodies was detected to following boron derivatives such as boric acid, boron penta (BP), and T-Boron (DPD) in the absence of boron treatment using the indirect immunohistochemical method.The evaluation of these staining was done using the H-scoring system. Results: It was found that immunoreactivities of VEGF, eNOS, and iNOS increased on control compared to those of the cells of MDA-MB231 human breast cancer cell line. Following boron derivatives treatment, it was observed that they were inhibited the VEGF/NOS labeling in MDA-MB-231 breast cancer cells. Conclusion: The present data suggest that BP, especially DPD, inhibits the angiogenesis of breast cancer cells through VEGF pathway. From this point, these boron derivatives may provide a novel therapeutic approach for breast cancer treatment.