Search

Your search keyword '"Sari, Murat"' showing total 558 results
Start Over Author "Sari, Murat"

Refine your results

more »

more »

more »

more »
558 results on '"Sari, Murat"'

6. A stability preserved time-integration method for nonlinear advection-diffusion models

Author

Tunc, Huseyin and Sari, Murat

Subjects
Mathematics - Numerical Analysis, 65L05, 65L06, 34K28
Abstract

A new implicit-explicit local differential transform method (IELDTM) is derived here for time integration of the nonlinear advection-diffusion processes represented by (2+1)-dimensional Burgers equation. The IELDTM is adaptively constructed as stability preserved and high order time integrator for spatially discretized Burgers equation. For spatial discretization of the model equation, the Chebyshev spectral collocation method (ChCM) is utilized. A robust stability analysis and global error analysis of the IELDTM are presented with respect to the direction parameter \theta. With the help of the global error analysis, adaptivity equations are derived to minimize the computational costs of the algorithms. The produced method is shown to eliminate the accuracy disadvantage of the classical \theta-method and the stability disadvantages of the existing DTM-based methods. Two examples of the Burgers equation in one and two dimensions have been solved via the ChCM-IELDTM hybridization, and the produced results are compared with the literature. The present time integrator has been proven to produce more accurate numerical results than the MATLAB solvers, ode45 and ode15s., Comment: 17 pages, 4 figures and 2 tables

Published
2021
Full Text
View/download PDF

7. A spatial local method for solving 2D and 3D advection-diffusion equations

Author

Tunc, Huseyin and Sari, Murat

Subjects
Mathematics - Numerical Analysis, 65N35, 65N12
Abstract

In this study, an implicit-explicit local differential transform method (IELDTM) based on Taylor series representations is produced for solving 2D and 3D advection-diffusion equations. The parabolic advection-diffusion equations are reduced to the nonhomogeneous elliptic system of partial differential equations with the utilization of the Chebyshev spectral collocation approach in temporal variable. The IELDTM is constructed over 2D and 3D meshes using continuity equations of the neighbour representations with either explicit or implicit forms in related directions. The IELDTM is proven to have excellent convergence properties by experimentally illustrating both h-refinement and p-refinement outcomes. A distinctive feature of the IELDTM over existing numerical techniques is the optimization of the local spatial degrees of freedom. It has been proven that IELDTM provides more accurate results with far less degrees of freedom than the finite difference, finite element and spectral methods.

Published
2021

8. A New Implicit-Explicit Local Method to Capture Stiff Behavior with COVID-19 Outbreak Application

Author

Tunc, Huseyin and Sari, Murat

Subjects
Mathematics - Numerical Analysis, 65L04, 65L05, 65L06, 65L20
Abstract

In this paper, a new implicit-explicit local method with an arbitrary order is produced for stiff initial value problems. Here, a general method for one-step time integrations has been created, considering a direction free approach for integrations leading to a numerical method with parameter-based stability preservation. Adaptive procedures depending on the problem types for the current method are explained with the help of local error estimates to minimize the computational cost. Priority error analysis of the current method is made, and order conditions are presented in terms of direction parameters. Stability analysis of the method is performed for both scalar equations and systems of differential equations. The currently produced parameter-based method has been proven to provide A-stability, for 0.5<\theta<1, in various orders. The present method has been shown to be a very good option for addressing a wide range of initial value problems through numerical experiments. It can be seen as a significant contribution that the Susceptible-Exposed-Infected-Recovered equation system parameterized for the COVID-19 pandemic has been integrated with the present method and stability properties of the method have been tested on this stiff model and significant results are produced. Some challenging stiff behaviours represented by the nonlinear Duffing equation, Robertson chemical system, and van der Pol equation have also been integrated, and the results revealed that the current algorithm produces much more reliable results than numerical techniques in the literature.

Published
2021

14. Clinicopathologic Features And Efficacy Of Induction Chemotherapy In Nasopharyngeal Carcinoma: Real-World Experience

Author

Majidova, Nargiz, primary, Sari, Murat, additional, Kahvecıglu, Fatma Akdag, additional, Ozcan, Erkan, additional, Akdag, Mutıanur Ozkorkmaz, additional, Dogan, Akıf, additional, Yıldırım, Sedat, additional, Sonusen, Sermın Dınc, additional, Yunusov, Emıl, additional, Yasar, Alper, additional, Celebi, Abdussamet, additional, Sever, Nadıye, additional, Kocaaslan, Erkam, additional, Erel, Pınar, additional, Agyol, Yesım, additional, Guren, Ali Kaan, additional, Arikan, Rukiye, additional, Işık, Selver, additional, Balvan, Ozlem, additional, Geredeli, Caglayan, additional, Uygun, Kazım, additional, Hacıbekiroğlu, Ilhan, additional, Kostek, Osman, additional, and Bayoğlu, İbrahim Vedat, additional

Published
2024
Full Text
View/download PDF

18. Improving Predictive Efficacy for Drug Resistance in Novel HIV-1 Protease Inhibitors through Transfer Learning Mechanisms

Author

Tunc, Huseyin, Yilmaz, Sumeyye, Darendeli Kiraz, Busra Nur, Sari, Murat, Kotil, Seyfullah Enes, Sensoy, Ozge, and Durdagi, Serdar

Abstract

The human immunodeficiency virus presents a significant global health challenge due to its rapid mutation and the development of resistance mechanisms against antiretroviral drugs. Recent studies demonstrate the impressive performance of machine learning (ML) and deep learning (DL) models in predicting the drug resistance profile of specific FDA-approved inhibitors. However, generalizing ML and DL models to learn not only from isolates but also from inhibitor representations remains challenging for HIV-1 infection. We propose a novel drug-isolate-fold change (DIF) model framework that aims to predict drug resistance score directly from the protein sequence and inhibitor representation. Various ML and DL models, inhibitor representations, and protein representations were analyzed through realistic validation mechanisms. To enhance the molecular learning capacity of DIF models, we employ a transfer learning approach by pretraining a graph neural network (GNN) model for activity prediction on a data set of 4855 HIV-1 protease inhibitors (PIs). By performing various realistic validation strategies on internal and external genotype–phenotype data sets, we statistically show that the learned representations of inhibitors improve the predictive ability of DIF-based ML and DL models. We achieved an accuracy of 0.802, AUROC of 0.874, and rof 0.727 for the unseen external PIs. By comparing the DIF-based models with a null model consisting of isolate-fold change (IF) architecture, it is observed that the DIF models significantly benefit from molecular representations. Combined results from various testing strategies and statistical tests confirm the effectiveness of DIF models in testing novel PIs for drug resistance in the presence of an isolate.

Published
2024
Full Text
View/download PDF

19. The prognostic factors in patients with advanced hepatocellular carcinoma: impact of treatment sequencing

Author

Köstek, Osman, Demirel, Ahmet, Hacıoğlu, Muhammet Bekir, Tastekin, Didem, Karabulut, Senem, Gündogdu, Abidin, Sever, Nadiye, Ayhan, Murat, Çelebi, Abdussamed, Majidova, Nargiz, Yaşar, Alper, Ağyol, Yeşim, Erel, Pınar, Kocaaslan, Erkam, Güren, Ali Kaan, Arıkan, Rukiye, Isık, Selver, Ercelep, Ozlem, Goksu, Sema Sezgin, Alandag, Celal, Bilgetekin, İrem, Caner, Burcu, Sahin, Ahmet Bilge, Gulmez, Ahmet, Akagunduz, Baran, Kose, Fatih, Kaplan, Muhammet Ali, Dogan, Ender, Sakalar, Teoman, Guven, Deniz Can, Gurbuz, Mustafa, Ergun, Yakup, Karaagac, Mustafa, Turker, Sema, Ozkul, Ozlem, Yıldız, Birol, Sahin, Süleyman, Demiray, Atike Gokcen, Sari, Murat, Erdogan, Bülent, Hacıbekiroglu, İlhan, Çakmak Öksüzoğlu, Ömür Berna, Kilickap, Saadettin, Bilici, Ahmet, Bayoglu, İbrahim Vedat, Topaloglu, Sernaz, and Cicin, İrfan

Abstract

AbstractThe prognosis of patients with advanced HCC can vary widely depending on factors such as the stage of the cancer, the patient’s overall health, and treatment regimens. This study aimed to investigate survival outcomes and associated factors in patients with hepatocellular carcinoma (HCC). In this retrospective study, data from 23 medical oncology clinics were analyzed. Progression-free survival (PFS) and overall survival (OS) values were estimated using the Kaplan–Meier method. Prognostic factors associated with survival which were identified in univariate analysis were subsequently evaluated in a multivariate Cox-regression survival analysis was conducted using the backward stepwise (Conditional LR) method to determine the independent predictors of PFS and OS. Of 280 patients, 131 received chemotherapy and 142 received sorafenib, 6 received atezolizumab plus bevacizumab and 1 received nivolumab for first-line setting. The median follow-up time was 30.4 (95%CI 27.1–33.6) months. For-first line, median PFS was 3.1 (95%CI2.7–3.5) months, and it was significantly longer in patients who received sorafenib or atezolizumab-bevacizumab or nivolumab (PFS 5.8 (95%CI 4.2–7.5) than in those received chemotherapy (PFS 2.1 (95%CI 1.9–2.3) in the first-line setting (p < 0.001). Multivariate analysis revealed that male gender (HR: 2.75, 95% CI: 1.53–4.94, p = 0.01), poor ECOG performance score (HR: 1.88, 95% CI: 1.10–3.21, p = 0.02), higher baseline AFP level (HR: 2.38, 95% CI: 1.54–3.67, p < 0.001) and upfront sorafenib treatment (HR,0.38; 95% CI: 0.23–0.62, p < 0.001) were significantly associated with shorter PFS. The median OS was 13.2 (95%CI 11.1–15.2) months. It was significantly longer in patients who received sorafenib or atezolizumab-bevacizumab or nivolumab in the first-line setting followed by TKIs (sorafenib or regorafenib, OS 18.6 (95%CI 13.8–23.5)) compared to those who received chemotherapy (OS 10.3 (95%CI 6.6–14.1)) in the first-line setting. The multivariate analysis revealed that upfront chemotherapy treatment approach, male gender (HR: 1.77, 95% CI: 1.07–2.94, p = 0.02), poor ECOG performance score (HR: 1.96, 95% CI: 1.24–3.09, p = 0.004) and Child-Pugh score, presence of extrahepatic disease (HR: 1.54, 95% CI: 1.09–2.18, p = 0.01), and higher baseline AFP value (HR: 1.50, 95% CI: 1.03–2.19, p = 0.03) were significantly associated with poor prognosis. Additionally, regarding of treatment sequence, upfront sorafenib followed by regorafenib showed a significantly lower risk of mortality (HR: 0.40, 95% CI: 0.25–0.66, p < 0.001). Sorafenib followed by regorafenib treatment was associated with a significantly lower risk of mortality rather than upfront sorafenib followed by BSC group or upfront chemotherapy followed by TKIs. These findings underscore the importance of the optimal treatment sequences to improve survival in patients with advanced HCC.

Published
2024
Full Text
View/download PDF

20. Traveling waves reflecting various processes represented by reaction–diffusion equations.

Author

Sari, Murat, Yokus, Asif, Duran, Serbay, and Durur, Hulya

Subjects
*POPULATION density, *DIFFUSION coefficients, *VALUES (Ethics), *BIOLOGY, *EQUATIONS
Abstract

The aim of this paper is to discover analytically the interactional responses of populations in a dynamic region where the reaction–diffusion process with forcing effects takes place through traveling wave solutions. An expansion method is considered here to properly capture the responses for the first time. In order to profoundly analyze the physical and mathematical discussions, some illustrative behavioral results are exhibited for various values of physical parameters. Especially for the different values of diffusion coefficients in the model under consideration, their effects on the behavior of the solitary wave are discussed and observationally supported by considering various illustrations. It is also seen that the solutions representing the diffusion seen to be in the form of the behavior of hexagonal Turing patterns in different time periods. The application of this study in mathematical biology is to analyze the relationship between the population density of certain species in any local region and the specific population density with invasion characteristics. In addition, the formation of the extinction vortex of the invading population, depending on the characteristics of the solutions presented, is also descriptively discussed. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

21. BIOMEDICAL MODELLING THROUGH PATH ANALYSIS APPROACH.

Author

AHMAD, Arshed A., SARI, Murat, and DEMİR, Ibrahim

Subjects
*PATH analysis (Statistics), *MEDICAL personnel, *BLOOD diseases, *MEDICAL research, *TREATMENT programs
Abstract

Since blood disease markers are one of the most prevalent health problems in this era, the aim of this study is to forecast pathological subjects from a population through biomedical variables of individuals using the currently produced path analysis (PA) model. In terms of the dataset, 539 subjects were used to implement this study. A mathematical approach based on the PA has been used to create a reliable biomedical model in this research that investigates if there exists a relation between the various anemia types and the biomedical variables through observational variables (the blood variables, age, and sex) and anemia types. Other linear approaches were taken into consideration for comparison, in terms of R² value of the model, which has a value of 0.699. The findings reveal that the model has great predictive potential. It is believed that the developed model, which includes observational variables, will help healthcare providers predictively plan appropriate treatment programs for their patients. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

22. Some Difference Algorithms for Nonlinear Klein-Gordon Equations

Author

Zeytinoglu, Asuman, Sari, Murat, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Nikolov, Geno, editor, Kolkovska, Natalia, editor, and Georgiev, Krassimir, editor

Published
2019
Full Text
View/download PDF

29. Constrained Paracomplex Mechanical Systems

Author

Tekkoyun, Mehmet and Sari, Murat

Subjects
Mathematics - Dynamical Systems, Mathematical Physics, 53C15, 70H03, 70H05
Abstract

In this study, it is introduced paracomplex analogue of Lagrangians and Hamiltonians with constraints in the framework of para-Kaehlerian manifolds. The geometrical and mechanical results on the constrained mechanical system have also been discussed.

Published
2009

30. Bi-Para-Mechanical Systems on Lagrangian Distributions

Author

Tekkoyun, Mehmet and Sari, Murat

Subjects
Mathematical Physics, PACS: 02.04, 03.40.
Abstract

In this work, bi-para-complex analogue of Lagrangian and Hamiltonian systems was introduced on Lagrangian distributions. Yet, the geometric and physical results related to bi-para-dynamical systems were also presented., Comment: 12 pages

Published
2009

31. An investigation on the estimation of the impact factors of pandemic deaths with artificial neural network and multiple regression algorithms: Covid-19 case.

Author

DEMİR, İbrahim, SARI, Murat, GÜLEN, Seda, and BALACESCU, Aniela

Subjects
*ARTIFICIAL neural networks, *COVID-19 pandemic, *MULTIPLE regression analysis, *PANDEMICS
Abstract

This article aims to successfully estimate the number of deaths in a pandemic, with the appropriate implementation of two new modelling approaches, artificial neural network and multiple regression analysis. Then, these methods have been used comparatively to predict death cases for the future course of the COVID-19 outbreak. These approaches proposed for estimation appear to result in few errors and perform well in providing information on the course of deaths in the epidemic. The agreement between the predicted results by these methods, and the actual data proves the superiority of the proposed ones in forecasting accuracy in future cases. This is expected to provide significant benefits in increasing the effectiveness of health policies to be implemented within the scope of the measures to be taken for the future of this and similar epidemics. As this investigation reveals that the current modelling methods have undeniable advantages in predicting epidemic trends, using our models is believed to provide an accurate estimate of death rates and guide policymakers in formulating research, health, socio-economic and fiscal policies. All these findings can be widely regarded as significant milestones and essential guides for researchers examining potential future epidemic tendencies. In addition, although this epidemic is quite complex and varies from country-to-country and various factors, the proposed approaches offer a great opportunity to model the outbreak in other epidemics as well as in other countries. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

32. Symmetric Teleparallel Gravity: Some exact solutions and spinor couplings

Author

Adak, Muzaffer, Sert, Özcan, Kalay, Mestan, and Sarı, Murat

Subjects
General Relativity and Quantum Cosmology
Abstract

In this paper we elaborate on the symmetric teleparallel gravity (STPG) written in a non-Riemannian spacetime with nonzero nonmetricity, but zero torsion and zero curvature. Firstly we give a prescription for obtaining the nonmetricity from the metric in a peculiar gauge. Then we state that under a novel prescription of parallel transportation of a tangent vector in this non-Riemannian geometry the autoparallel curves coincides with those of the Riemannian spacetimes. Subsequently we represent the symmetric teleparallel theory of gravity by the most general quadratic and parity conserving lagrangian with lagrange multipliers for vanishing torsion and curvature. We show that our lagrangian is equivalent to the Einstein-Hilbert lagrangian for certain values of coupling coefficients. Thus we arrive at calculating the field equations via independent variations. Then we obtain in turn conformal, spherically symmetric static, cosmological and pp-wave solutions exactly. Finally we discuss a minimal coupling of a spin-1/2 field to STPG., Comment: Accepted for publication in the International Journal of Modern Physics A

Published
2008
Full Text
View/download PDF

35. The Effectiveness of Adjuvant PD-1 Inhibitors in Patients With Surgically Resected Stage III/IV Acral Melanoma

Author

Arak, Haci, Erkiliç, Suna, Yaslikaya, Şendağ, Eylemer Mocan, Eda, Aktaş, Gökmen, Özdemir, Melek, Semiz, Hüseyin Salih, kiliçkap, Saadettin, Özalp, Faruk Recep, Sever, Özlem Nuray, Akdağ, Goncagül, Ağaoğlu, Ahmet Burak, Özçelik, Melike, Sari, Murat, Arcagök, Murat, Anik, Hicran, Yayla, Şaziye Burçak, Sever, Nadiye, Açar, Fatma Pinar, Bayrakçi, İsmail, Turhal, Serdar, Ayhan, Murat, and Kuş, Tülay

Abstract

Our aim was to assess the efficacy of adjuvant programmed cell death protein-1 (PD-1) inhibitors and compare the other adjuvant treatments in patients with surgically resected stage III or IV acral melanoma. This study is a multicenter, retrospective analysis. We included 114 patients with stage III or IV acral malignant melanoma who underwent surgery within the past 10 years. We analyzed the effect of adjuvant programmed cell death protein-1 inhibitors on disease-free survival (DFS). The mean follow-up was 40 months, during which 69 (59.5%) patients experienced recurrence. Among the participants, 64 (56.1%) received systemic adjuvant therapy. Specifically, 48.4% received anti–PD-1 therapy, 29.7% received interferon, 14.1% received tezozolomide, and 7.8% received B-Raf proto-oncogene/mitogen-activated protein kinase inhibitors. Patients who received adjuvant therapy had a median DFS of 24 (10.9–37.2) months, whereas those who did not receive adjuvant therapy had a median DFS of 15 (9.8–20.2) months. Multivariate analysis for DFS revealed that the receipt of adjuvant therapy and lymph node metastasis stage were independent significant parameters (P= 0.021, P= 0.018, respectively). No statistically significant difference was observed for DFS between programmed cell death protein-1 inhibitor treatment and other adjuvant treatments. Regarding overall survival (OS), patients who received adjuvant treatment had a median OS of 71 (30.4–111.7) months, whereas those who did not receive adjuvant treatment had a median OS of 38 (16.7–59.3; P= 0.023) months. In addition, there were no significant differences in OS observed between various adjuvant treatment agents (P= 0.122). In our study, we have shown that adjuvant therapy had a positive effect on both DFS and OS in patients with stages III–IV acral melanoma who underwent curative intent surgery. Notably, we found no significant differences between anti–PD-1 therapy and other adjuvant therapies.

Published
2024
Full Text
View/download PDF

37. Mathematical modelling of antibiotic interaction on evolution of antibiotic resistance: an analytical approach.

Author

Nashebi, Ramin, Sari, Murat, and Kotil, Seyfullah Enes

Subjects
DRUG resistance in bacteria, ANTIBIOTICS, ANTIBIOSIS, MATHEMATICAL models, DRUG resistance in microorganisms
Abstract

Background: The emergence and spread of antibiotic-resistant pathogens have led to the exploration of antibiotic combinations to enhance clinical effectiveness and counter resistance development. Synergistic and antagonistic interactions between antibiotics can intensify or diminish the combined therapy's impact. Moreover, these interactions can evolve as bacteria transition from wildtype to mutant (resistant) strains. Experimental studies have shown that the antagonistically interacting antibiotics against wildtype bacteria slow down the evolution of resistance. Interestingly, other studies have shown that antibiotics that interact antagonistically against mutants accelerate resistance. However, it is unclear if the beneficial effect of antagonism in the wildtype bacteria is more critical than the detrimental effect of antagonism in the mutants. This study aims to illuminate the importance of antibiotic interactions against wildtype bacteria and mutants on the deacceleration of antimicrobial resistance. Methods: To address this, we developed and analyzed a mathematical model that explores the population dynamics of wildtype and mutant bacteria under the influence of interacting antibiotics. The model investigates the relationship between synergistic and antagonistic antibiotic interactions with respect to the growth rate of mutant bacteria acquiring resistance. Stability analysis was conducted for equilibrium points representing bacteria-free conditions, all-mutant scenarios, and coexistence of both types. Numerical simulations corroborated the analytical findings, illustrating the temporal dynamics of wildtype and mutant bacteria under different combination therapies. Results: Our analysis provides analytical clarification and numerical validation that antibiotic interactions against wildtype bacteria exert a more significant effect on reducing the rate of resistance development than interactions against mutants. Specifically, our findings highlight the crucial role of antagonistic antibiotic interactions against wildtype bacteria in slowing the growth rate of resistant mutants. In contrast, antagonistic interactions against mutants only marginally affect resistance evolution and may even accelerate it. Conclusion: Our results emphasize the importance of considering the nature of antibiotic interactions against wildtype bacteria rather than mutants when aiming to slow down the acquisition of antibiotic resistance. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

38. The effect of parity, breastfeeding history, and duration on clinical and pathological characteristics of breast cancer patients.

Author

AK, Naziye, TUZ, Zeynep, AYDIN, Esra, FERHATOĞLU, Ferhat, SARI, Murat, PAKSOY, Nail, DOĞAN, İzzet, YILDIZ, Anıl, DİŞÇİ, Rian, and SAİP, Pınar Mualla

Subjects
CANCER patients, BREASTFEEDING, BREAST cancer, PROGESTERONE receptors, LYMPH nodes, ANKYLOGLOSSIA
Abstract

Background/aim: The study is aimed to determine the relationship between the delivery and breastfeeding history of the patients and the clinicopathological properties of breast cancer. Materials and methods: A questionnaire was utilized for the study, which included the age of diagnosis, the number of children at the time of diagnosis, the age of the children, and the breastfeeding period of each child. Results: The study included 828 patients. The median age at diagnosis was 47 years for parous women and 42 years for nonparous women (p < 0.001). The tumor size of the patients diagnosed within the breastfeeding period was significantly larger compared to the other patients. Estrogen and progesterone receptor positivity were lower in patients diagnosed during breastfeeding. Additionally, the mean number of positive lymph nodes, dissected lymph nodes, and positive lymph node/dissected lymph node ratio in parous and breastfed patients with a nonmetastatic disease were statistically significantly higher in multivariable analysis than those patients who were nulliparous and have not breastfed. Conclusion: Breast cancer is seen at a later age in patients who are parous than those who have never given birth. Patients who are parous and have breastfed tend to present with a higher stage of the disease. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

41. The effect of low HER2 expression on treatment outcomes in metastatic hormone receptor positive breast cancer patients treated with a combination of a CDK4/6 inhibitor and endocrine therapy: A multicentric retrospective study

Author

SARI, MURAT and ÇALIŞKAN YILDIRIM E., ATAĞ E., Coban E., Umit Unal O., Celebi A., Keser M., UZUN M., KESKİNKILIÇ M., Tanrikulu Simsek E., Sari M., et al.

Subjects
Internal Diseases, Cancer Research, palbociclib, SURGERY, Life Sciences (LIFE), Molecular Biology and Genetics, Sağlık Bilimleri, İç Hastalıkları, Clinical Medicine (MED), hormone positive, breast cancer, Surgery Medicine Sciences, BİYOKİMYA VE MOLEKÜLER BİYOLOJİ, Yaşam Bilimleri, Health Sciences, Klinik Tıp (MED), Cytogenetic, HER2-Low, ribociclib, Moleküler Biyoloji ve Genetik, Cerrahi, Internal Medicine Sciences, Klinik Tıp, Temel Bilimler, CERRAHİ, Life Sciences, Dahili Tıp Bilimleri, CLINICAL MEDICINE, ONCOLOGY, Onkoloji, Tıp, MOLECULAR BIOLOGY & GENETICS, Oncology, Yaşam Bilimleri (LIFE), Cerrahi Tıp Bilimleri, Medicine, ONKOLOJİ, Surgery, Natural Sciences, BIOCHEMISTRY & MOLECULAR BIOLOGY, Sitogenetik, Kanser Araştırmaları
Abstract

Background: CDK4/6 inhibitors combined with endocrine therapy have significantly improved treatment outcomes for metastatic hormone receptor-positive (HR+) breast cancer patients. However, the impact of low HER2 expression on treatment response and progression-free survival (PFS) remains unclear. Methods: This multicenter retrospective study included 204 HR+ breast cancer patients treated with a combination of CDK4/6 inhibitor and endocrine therapy. HER2-zero disease was detected in 138 (68%) and HER2-low disease in 66 (32%) patients. Treatment-related characteristics and clinical outcomes were analyzed, with a median follow-up of 22 months. Results: The objective response rate (ORR) was 72.7% in the HER2 low group and 66.6% in the HER2 zero group (p = 0.54). Median PFS was not significantly different between the HER2-low and HER2 zero groups (19 months vs.18 months, p = 0.89), although there was a trend toward longer PFS in the HER2-low group for first-line treatment (24 months progression-free survival rate 63% vs 49%). In recurrent disease, the median PFS was 25 months in the HER2-low group and 12 months in the HER2-zero group (p = 0.08), while in de novo metastatic disease, the median PFS was 18 months in the HER2-low group and 27 months in the HER2-zero group (p = 0.16). The order of CDK4/6 inhibitor use and the presence of visceral metastasis were identified as independent variables affecting PFS. Conclusion: Low HER2 expression did not significantly impact treatment response or PFS in HR+ breast cancer patients treated with a CDK4/6 inhibitor and endocrine therapy. Because of the conflicting results in the literature, further prospective studies are needed to evaluate the clinical significance of HER2 expression in HR+ breast cancer.

Published
2023

42. Seismic wave modelling using the boundary element method

Author

Sari, Murat

Subjects
519, Applied mathematics
Abstract

The main objective of this thesis is to use the boundary element method as an efficient and advantageous numerical approach to model the seismic signals received at selected receiver points due to a source located within a geophysical structure. These signals may travel through different geophysical structures. This work determines whether rock interfaces can be identified from the signals received at selected points. The method proves to be most satisfactory and more easily applicable for unbounded media than for bounded media. Each layer in the media of interest is assumed to be linearly elastic, homogeneous and isotropic. This assumption is used for both two- and three-dimensional geometries. Throughout this research linear and constant time approximations are used to represent the displacements and tractions, respectively. With the use of these temporal variations all time integrations are evaluated analytically. The two-dimensional boundary kernels and internal flux kernels have been derived. New kernels for boundary and internal points have also been obtained for three-dimensional scalar waves. In addition, the three­ dimensional elastodynamic boundary kernels have been evolved. Constant elements are normally employed to discretize the boundary. To determine the dynamical response constant elements are seen to be well suited for the geometries used here. The improper integrals are evaluated analytically in two dimensions. In three dimensions two different techniques are used to cope with the singularities. Some available computer codes for the boundary nodes are extended to determine material behaviour at internal points. For three-dimensional cases some programs are developed with the help of the two-dimensional programs. For layered materials these codes are expanded for each layer as subprogram. In spite of the fact that the existence of the interfaces makes the solution of the problem tend to instability, this analysis shows that the BEM is capable of treating layered media problems. In general, the examples presented show that the time domain direct BEM is stable for practical applications. Some supplemental layered media results are also presented to show the usefulness and range of the method in real applications. These results also demonstrate the validity of the extended and developed programs in this thesis. Where possible the current work is compared with that of others. Strong interface and other reflections are visible in all seismograms though somewhat weaker in the case of three dimensions. The potential and flux changes across a plane body have been examined in two and three dimensions.

Published
2000

46. The effect of low HER2 expression on treatment outcomes in metastatic hormone receptor positive breast cancer patients treated with a combination of a CDK4/6 inhibitor and endocrine therapy: A multicentric retrospective study

Author

KESKİNKILIÇ, MERVE, Tanrikulu Simsek, Eda, Sari, Murat, Yavuzsen, TUĞBA, Keser, Murat, ÇALIŞKAN YILDIRIM, EDA, ATAĞ, ELİF, Coban, Ezgi, Umit Unal, Olcun, Celebi, Abdussamet, and UZUN, MEHMET

Abstract

Background: CDK4/6 inhibitors combined with endocrine therapy have significantly improved treatment outcomes for metastatic hormone receptor-positive (HR+) breast cancer patients. However, the impact of low HER2 expression on treatment response and progression-free survival (PFS) remains unclear. Methods: This multicenter retrospective study included 204 HR+ breast cancer patients treated with a combination of CDK4/6 inhibitor and endocrine therapy. HER2-zero disease was detected in 138 (68%) and HER2-low disease in 66 (32%) patients. Treatment-related characteristics and clinical outcomes were analyzed, with a median follow-up of 22 months. Results: The objective response rate (ORR) was 72.7% in the HER2 low group and 66.6% in the HER2 zero group (p = 0.54). Median PFS was not significantly different between the HER2-low and HER2 zero groups (19 months vs.18 months, p = 0.89), although there was a trend toward longer PFS in the HER2-low group for first-line treatment (24 months progression-free survival rate 63% vs 49%). In recurrent disease, the median PFS was 25 months in the HER2-low group and 12 months in the HER2-zero group (p = 0.08), while in de novo metastatic disease, the median PFS was 18 months in the HER2-low group and 27 months in the HER2-zero group (p = 0.16). The order of CDK4/6 inhibitor use and the presence of visceral metastasis were identified as independent variables affecting PFS. Conclusion: Low HER2 expression did not significantly impact treatment response or PFS in HR+ breast cancer patients treated with a CDK4/6 inhibitor and endocrine therapy. Because of the conflicting results in the literature, further prospective studies are needed to evaluate the clinical significance of HER2 expression in HR+ breast cancer.

Published
2023

49. Fıkıh Usûlünde Mutlak'ın Mukayyed'e Haml’i.

Author

SARI, Murat

Abstract

Copyright of Journal of Young Intellectuals / Genç Mütefekkirler Dergisi is the property of Journal of Young Intellectuals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2023

Catalog

Books, media, physical & digital resources
See catalog results