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Öğe Comparison of Bayesian survival analysis and Cox regression analysis in simulated and breast cancer data sets(Pergamon-Elsevier Science Ltd, 2009) Omurlu, Imran Kurt; Ozdamar, Kazim; Ture, MevlutWe aimed to compare the performance of Cox regression analysis (CRA) and Bayesian survival analysis (BSA) by using simulations and breast cancer data. Simulation study was carried out with two different algorithms that were informative and noninformative priors. Moreover, in a real data set application, breast cancer data set related to disease-free survival (DFS) that was obtained from 423 breast cancer patients diagnosed between 1998 and 2007 was used. In the simulation application, it was observed that BSA with noninformative priors and CRA methods showed similar performances in point of convergence to simulation parameter. In the informative priors' simulation application, BSA with proper informative prior showed a good performance with too little bias. It was found out that the bias of BSA increased while priors were becoming distant from reliability in all sample sizes. In addition, BSA obtained predictions with more little bias and standard error than the CRA in both small and big samples in the light of proper priors. In the breast cancer data set, age, tumor size, hormonal therapy, and axillary nodal status were found statistically significant prognostic factors for DFS in stepwise CRA and BSA with informative and noninformative priors. Furthermore, standard errors of predictions in BSA with informative priors were observed slightly. As a result, BSA showed better performance than CRA, when subjective data analysis was performed by considering expert opinions and historical knowledge about parameters. Consequently, BSA should be preferred in existence of reliable informative priors, in the contrast cases, CRA should be preferred. (C) 2009 Elsevier Ltd. All rights reserved.Öğe The comparisons of prognostic indexes using data mining techniques and Cox regression analysis in the breast cancer data(Pergamon-Elsevier Science Ltd, 2009) Ture, Mevlut; Tokatli, Fusun; Omurlu, Imran KurtThe purpose of this study is to determine new prognostic indexes for the differentiation of subgroups of breast cancer patients with the techniques of decision tree algorithms (C&RT, CHAID, QUEST, ID3, C4.5 and C5.0) and Cox regression analysis for disease-free survival (DFS) in breast cancer patients. A retrospective analysis was performed in 381 breast cancer patients diagnosed. Age, menopausal status, age of menarche, family history of cancer, histologic tumor type, quadrant of tumor, tumor size, estrogen and progesterone receptor status, histologic and nuclear grading, axillary nodal status, pericapsular involvement of lymph nodes, lymphovascular and perineural invasion, adjuvant radiotherapy, chemotherapy and hormonal therapy were assessed. Based on these prognostic factors, new prognostic indexes for C&RT, CHAID, QUEST, ID3, C4.5 and C5.0 and Cox regression were obtained. Prognostic indexes showed a good degree of classification, which demonstrates that an improvement seems possible using standard risk factors. We obtained that C4.5 has a better performance than C&RT, CHAID, QUEST, ID3, C5.0 and Cox regression to determine risk groups using Random Survival Forests (RSF). (C) 2008 Elsevier Ltd. All rights reserved.Öğe The comparisons of random survival forests and Cox regression analysis with simulation and an application related to breast cancer(Pergamon-Elsevier Science Ltd, 2009) Omurlu, Imran Kurt; Ture, Mevlut; Tokatli, FuesunThe objective of this study was to compare the performances of Cox regression analysis (CRA) and random survival forests (RSF) methods with simulation and a real data set related to breast cancer. In the simulations, we compared across the methods under varying sample sizes by using Monte Carlo simulation method. The results showed that the performance of the CRA was a slightly better for analysis based on Harrell's concordance index than RSF approaches based on log-rank, conservation of events, log-rank score and approximate log-rank splitting rules. In the real data application, a retrospective analysis was performed in 279 breast cancer patients diagnosed. According to Harrell's concordance index, RSF based on approximate log-rank splitting rule to determined major risk factors for disease-free survival (DFS) showed a slightly better performance than other approaches. In general, performances of all the methods were almost similar. The predictive capability of CRA can be used for different sample sizes and potential future suitable survival data problems, whereas RSF provide interpretive results. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Developing and comparing two different prognostic indexes for predicting disease-free survival of nonmetastatic breast cancer patients(Tubitak Scientific & Technological Research Council Turkey, 2011) Tokatli, Zehra Fusun; Ture, Mevlut; Omurlu, Imran Kurt; Alas, Rusen Cosar; Uzal, Mustafa CemAim: To determine 2 different prognostic indexes (PI) for the differentiation of subgroups of nonmetastatic breast cancer patients with the Cox regression analysis and survival tree (ST) methods and the additional usage of the Kaplan-Meier estimates to investigate the predictive power of these methods. Materials and methods: Prognostic factors data were collected for 410 patients. The Cox regression analysis examines the relationship of the survival distribution and covariates. The ST method is a tree-structured survival analysis based on a recursive partitioning algorithm. In this study, Harrell's concordance indexes of models for training and test sets were computed. Furthermore, survival curves were estimated by the Kaplan-Meier method. Disease-free survival (DFS) was calculated from the time of initial diagnosis (initiation of the first treatment) to the first recurrence of disease. Results: After a median follow-up of 48 months, 100 (24.4%) patients have had at least 1 of the DFS events. In Cox regression analysis, we proposed the simple PI, which is a sum of axillary nodal and HER2/neu status. In the ST method, we identified 3 variables: HER2/neu, axillary nodal, and estrogen receptor status. The axillary nodal status was the most important determining factor for recurrence. Conclusion: We found that the PI of the ST and Cox regression methods had similar performance levels in predicting DFS, and the error rates of the models were close to each other in the training and test sets. Furthermore, we determined that the axillary nodal status and HER2/neu were the most important determining factors for prediction of DFS in breast cancer patients.Öğe Effect of Lidocaine on Reducing Injury in a Rat Electrical Burn Model(Lippincott Williams & Wilkins, 2012) Benlier, Erol; Eskiocak, Sevgi; Puyan, Fulya Oz; Sikar, Emel Yurdakul; Kandulu, Huseyin; Omurlu, Imran Kurt; Top, HusamettinElectrical injuries induce progressive tissue loss. We evaluated the effect of lidocaine on tissue necrosis after electrical burn injuries. Forty-two male Wistar albino rats (250-300 g) were divided into 3 groups [Group A (n = 6), control group without an electrical burn injury; and Groups B (n = 18) and C (n = 18), electrical burn injury groups without and with lidocaine therapy, respectively]. Three separate analyses were performed at different time points on 6 of 18 rats from Groups B and C at each time point. Electrical burns were induced by applying 220 V AC between the left upper and right lower extremities for 10 seconds. Myeloperoxidase and malondialdehyde levels were measured in skin and muscle biopsy specimens after the first hour, fresh and dry weight differences in the amputated extremities were calculated after 24 hours, and live and necrotic tissue areas were measured at 7 days after burn injury. We found that lidocaine reduced edema, the number of neutrophils, and neutrophil damage in tissues. We conclude that lidocaine decreased the amount of necrotic tissue caused by electric injury.Öğe Effect of the Pruritus on the Quality of Life: A Preliminary Study(Korean Dermatological Assoc, 2012) Erturk, Irem Eren; Arican, Ozer; Omurlu, Imran Kurt; Sut, NecdetBackground: Pruritus affects the quality of life (QoL) in the patients. However, little is known of the impacts of itching on the QoL in the literature. Objective: In this study, a questionnaire eliciting specific responses about pruritus was used to determine the effect of itching and its severity on QoL in chronic pruritic patients. Methods: One hundred ten adult patients with chronic pruritus were surveyed. Once itch severity had been self-reported by patients, together with Skindex-29, they have been given the 18-item Pruritus-related Life Quality Index (PLQI) questionnaire, which was used to generated the new index. Results: Significant correlations have been found between the pruritus severity score of participants and their total Skindex-29 (p < 0.001) with its function, emotion and symptom subscale scores (p < 0.001 for each). Also, significant correlations were evident between total PLQI (p < 0.001) and its psychosocial negativities, difficulties in everyday activities and social live subscale scores (p < 0.001 for each). In particular, the emotion subscale of Skindex-29 (p = 0.02) and psychosocial negativity subscale of PLQI (p = 0.02) were significantly high in psychopathologic patients. A highly positive statistical correlation between Skindex-29 and PLQI scales was evident (r = 0.845, p < 0.001). For reliability, Cronbach's coefficient a coefficients were 0.931 for the Skindex-29 scale and 0.918 for the PLQI scale. Conclusion: The results demonstrate that chronic pruritus appreciably reduces the QoL. PLQI could be used in the development of new questionnaires for determining the QoL of patients with chronic itch. (Ann Dermatol 24(4) 406 similar to 412, 2012)Öğe Effects of Curcumin on Apoptosis and Oxidoinflammatory Regulation in a Rat Model of Acetic Acid-Induced Colitis: The Roles of c-Jun N-Terminal Kinase and p38 Mitogen-Activated Protein Kinase(Mary Ann Liebert, Inc, 2013) Topcu-Tarladacalisir, Yeter; Akpolat, Meryem; Uz, Yesim Hulya; Kizilay, Gulnur; Sapmaz-Metin, Melike; Cerkezkayabekir, Aysegul; Omurlu, Imran KurtThe present study evaluated the effects of curcumin on epithelial cell apoptosis, the immunoreactivity of the phospho-c-Jun N-terminal kinase (JNK) and phospho-p38 mitogen-activated protein kinases (MAPKs) in inflamed colon mucosa, and oxidative stress in a rat model of ulcerative colitis induced by acetic acid. Rats were randomly divided into three groups: control, acetic acid, and acetic acid + curcumin. Curcumin (100 mg/kg per day, intragastrically) was administered 10 days before the induction of colitis and was continued for two additional days. Acetic acid-induced colitis caused a significant increase in the macroscopic and microscopic tissue ranking scores as well as an elevation in colonic myeloperoxidase (MPO) activity, malondialdehyde (MDA) levels, and the number of apoptotic epithelial cells in colon tissue compared to controls. In the rat colon, immunoreactivity of phospho-p38 MAPK was increased, whereas the phospho-JNK activity was decreased following the induction of colitis. Curcumin treatment was associated with amelioration of macroscopic and microscopic colitis sores, decreased MPO activity, and decreased MDA levels in acetic acid-induced colitis. Furthermore, oral curcumin supplementation clearly prevented programmed cell death and restored immunreactivity of MAPKs in the colons of colitic rats. The results of this study suggest that oral curcumin treatment decreases colon injury and is associated with decreased inflammatory reactions, lipid peroxidation, apoptotic cell death, and modulating p38- and JNK-MAPK pathways.Öğe Factors Effecting Job Satisfaction Among Academic Staff(Galenos Publ House, 2011) Dagdeviren, Nezih; Musaoglu, Zeliha; Omurlu, Imran Kurt; Oztora, SerdarObjective: In this paper, we aimed to investigate the job satisfaction levels of all the academic staff in Trakya University, along with their socioeconomic features. Material and Methods: We used a questionnaire including the Minnesota Satisfaction Questionnaire Short Form. Frequency tables, cross tabulations, Pearson Chi-square, Exact Chi-square, Kruskal-Wallis, Dunn's Multiple Comparison and Chi-squared Automatic Interaction Detector (CHAID) tests were used for statistical analysis. Results: The mean age of 560 participants was 33.86 +/- 7.33 years, of whom 47% (n=263) were female and 53% (n=297) male. Of the participants, the mean levels were 63.06 +/- 10.96 for general, 44.79 +/- 7.49 for intrinsic, and 18.27 +/- 4.64 for extrinsic job satisfaction. 85.4% of the academic staff (n=478) had a moderate level of satisfaction, whereas 14.6% (n=82) had a higher level. There was a significant relationship between income and job satisfaction levels. With the CHAID analysis, it was determined that job satisfaction had a relationship with age, educational status, total years of service and years of service in the current department. Conclusion: Job satisfaction can reflect the general emotional status of employees. It has a greater importance for the jobs that can affect the extraoccupational lives directly and require constant devotion. Employers should take some measures to increase job satisfaction in order to improve efficiency.Öğe Prognostic value DCE-MRI parameters in predicting factor disease free survival and overall survival for breast cancer patients(Elsevier Ireland Ltd, 2012) Tuncbilek, Nermin; Tokatli, Fusun; Altaner, Semsi; Sezer, Atakan; Ture, Mevlut; Omurlu, Imran Kurt; Temizoz, OsmanPurpose: The aim of the study is to assess the predictive power of DCE-MRI semi-quantitative parameters during treatment of breast cancer, for disease-free (DFS) and overall survival (OS). Materials and methods: Forty-nine women (age range, 28-84 years; mean, 50.6 years) with breast cancer underwent dynamic contrast enhancement MRI at 1.0 T imaging, using 2D FLASH sequences. Time intensity curves (TICs) were obtained from the regions showing maximal enhancement in subtraction images. Semi-quantitative parameters (TICs; maximal relative enhancement within the first minute, E (max/1); maximal relative enhancement of the entire study, E-max; steepest slope of the contrast enhancement curve; and time to peak enhancement) derived from the DCE-MRI data. These parameters were then compared with presence of recurrence or metastasis, DFS and OS by using Cox regression (proportional hazards model) analysis, linear discriminant analysis. Results: The results from of the 49 patients enrolled into the survival analysis demonstrated that traditional prognostic parameters (tumor size and nodal metastasis) and semi-quantitative parameters (E-max/1, and steepest slope) demonstrated significant differences in survival intervals (p < 0.05). Further Cox regression (proportional hazards model) survival analysis revealed that semi-quantitative parameters contributed the greatest prediction of both DFS, OS in the resulting models (for E-max/1: p = 0.013, hazard ratio 1.022; for stepest slope: p = 0.004, hazard ratio 1.584). Conclusion: This study shows that DCE-MRI has utility predicting survival analysis with breast cancer patients. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Öğe The Value of Serum MDA For the Diagnosis of Intracranial Injury(Aves Yayincilik, Ibrahim Kara, 2008) Kavalci, Cemil; Durukan, Polat; Ilhan, Necip; Guzel, Ahmet; Omurlu, Imran KurtObjectives: Malonyldialdehid (MDA) is one of the most sensitive parameters of the lipid peroxidation. In the present study, it was aimed to investigate the value of serum MDA levels in diagnosing intracranial pathologies in minor head trauma. Patients and Methods: This prospective study was approved in Firat University. Patients were categorized into 2 groups: those without intracranial lesions in head CTs (group 1) and those with intracranial lesions in head CTs (group 2). Serum MIDA levels were determined. Results: Mean serum MIDA levels in group 1 (n=50) and group 2 (n=24) were 31.186 +/- 46.9 pg/ml and 54.873 +/- 127.6 pg/ml, respectively. Statistical analysis showed no significant difference between the two groups in terms of MDA values. Conclusion: It is found that serum MDA has limited value in determining the intracranial injury detected with computed tomography in patients with minor head trauma.Öğe Vitamin E modulates apoptosis and c-jun N-terminal kinase activation in ovarian torsion-detorsion injury(Academic Press Inc Elsevier Science, 2013) Sapmaz-Metin, Melike; Topcu-Tarladacalisir, Yeter; Uz, Yesim Hulya; Inan, Mustafa; Omurlu, Imran Kurt; Cerkezkayabekir, Aysegul; Kizilay, GulnurThe aim of this study was to evaluate the role of vitamin E in follicular degeneration and to assess histopathological and biochemical changes following ischemia-reperfusion (IR) injury in rat ovaries. Twenty-eight Wistar albino rats were randomly divided into four groups: sham, 4 h torsion, 24 h detorsion, and a vitamin E group. Thirty minutes before detorsion, a single dose of 200 mg/kg vitamin E was administered intraperitoneally. The ovarian histology score was determined, serum levels of malondialdehyde (MDA) and myeloperoxidase (MPO) were measured. The apoptosis of granulosa cells and the phospho-c-jun N-terminal kinase (p-JNK) and phospho-p38 (p-p38) immunoreactivities of these cells were determined. MDA and MPO levels were significantly increased in the torsion and detorsion groups. Hemorrhage, edema, and congestion were also apparent in these groups. In addition, the apoptotic index and the immunoreactivity of p-JNK were highest in the detorsion group, which also showed marked follicular degeneration. However, p-p38 activity was not affected by torsion-detorsion (TD) induction. Vitamin E ameliorated TD-induced histological alterations. It also decreased serum levels of MDA and MPO, reduced the activity of p-JNK in the ovaries, and reduced numbers of apoptotic follicular cells. In conclusion, these data indicate that vitamin E attenuated ovarian follicular degeneration by inhibiting the immunoreactivity of p-JNK and reducing the apoptosis of granulosa cells. (c) 2013 Elsevier Inc. All rights reserved.
