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Istanbul, Turkey

Mahmutyazicioglu N.,Bogazici University | Albayrak O.,Mersin University | Ipekoglu M.,German-Turkish University | Altintas S.,Bogazici University
Journal of Materials Research | Year: 2013

In this study, a powder blend representing 6061 Al-alloy was first mixed with Al2O3 ceramic particles and then foamed by using the powder compact melting method. 6061-Al2O3 foams and control specimens 6061 foams (without ceramic reinforcement) were produced. The effects of both different ratios of Al2O3 particle addition and different kinds of heat treatment on hardenability, structure and mechanical behavior of the final foams were investigated. Foams that were fully heat treated had the highest hardness values, and they performed best with an increase in collapse strength up to 100% over the untreated samples. Improved cell structure and decreased drainage were obtained when the Al 2O3 addition was not more than 5 vol%. The compression test results were interpreted in terms of the foam's microstructure, and correlations were made relating to the unloading modulus and compression strength of the foams to the relative density. © Materials Research Society 2013. Source

Unal C.M.,German-Turkish University | Unal C.M.,TU Braunschweig | Steinert M.,TU Braunschweig | Steinert M.,Helmholtz Center for Infection Research
Biochimica et Biophysica Acta - General Subjects | Year: 2015

Background FK506-binding proteins (FKBPs) contain a domain with peptidyl-prolyl-cis/trans-isomerase (PPIase) activity and bind the immunosuppressive drugs FK506 and rapamycin. FKBPs belong to the immunophilin family and are found in eukaryotes and bacteria. Scope of review In this review we describe two major groups of bacterial virulence-associated FKBPs, the trigger factor and Mip-like PPIases. Moreover, we discuss the contribution of host FKBPs in bacterial infection processes. Major conclusions Since PPIases are regarded as alternative antiinfective drug targets we highlight current research strategies utilizing pipecolinic acid and cycloheximide derivatives as well as substrate based inhibitors. General significance The current research strategies suggest a beneficial synergism of drug development and basic research. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets. © 2014 Elsevier B.V. All rights reserved. Source

Unal C.M.,TU Braunschweig | Unal C.M.,German-Turkish University | Steinert M.,TU Braunschweig | Steinert M.,Helmholtz Center for Infection Research
Expert Opinion on Therapeutic Targets | Year: 2016

Introduction: In recent years, Clostridium difficile has become the primary cause of antibiotic-associated diarrhea and pseudomembranous colitis, resulting in long and complicated hospital stays that represent a serious burden for patients as well as health care systems. Currently, conservative treatment of C. difficile infection (CDI) relies on the antibiotics vancomycin, metronidazole or fidaxomicin, or in case of multiple recurrences, fecal microbiota transplantation (FMT).Areas covered: The fast-spreading, epidemic nature of this pathogen urgently necessitates the search for alternative treatment strategies as well as antibiotic targets. Accordingly, in this review, we highlight the recent findings regarding virulence associated traits of C. difficile, evaluate their potential as alternative drug targets, and present current efforts in designing inhibitory compounds, with the aim of pointing out possibilities for future treatment strategies.Expert opinion: Increased attention on systematic analysis of the virulence mechanisms of C. difficile has already led to the identification of several alternative drug targets. In the future, applying state of the art omics and the development of novel infection models that mimic the human gut, a highly complex ecological niche, will unveil the genomic and metabolic plasticity of this pathogen and will certainly help dealing with future challenges. © 2016 Taylor & Francis. Source

Rasch U.,TU Braunschweig | Unal C.M.,TU Braunschweig | Unal C.M.,German-Turkish University | Steinert M.,Helmholtz Center for Infection Research
Biochemical Society Transactions | Year: 2014

Legionella pneumophila, typically a parasite of free-living protozoa, can also replicate in human alveolar macrophages and lung epithelial cells causing Legionnaires' disease in humans, a severe atypical pneumonia. The pathogen encodes six peptidylprolyl cis-trans isomerases (PPIases), which generally accelerate folding of prolyl peptide bonds, and influence protein folding. PPIases can be divided into three classes, cyclophilins, parvulins and FK506-binding proteins (FKBPs). They contribute to a multitude of cellular functions including bacterial virulence. In the present review, we provide an overview of L. pneumophila PPIases, discussing their known and anticipated functions as well as moonlighting phenomena. By taking the example of the macrophage infectivity potentiator (Mip) of L. pneumophila, we highlight the potential of PPIases as promising drug targets. compilation © 2014 Biochemical Society. Source

Gok M.,Yalova University | Herand D.,German-Turkish University
MATEC Web of Conferences | Year: 2016

Prediction of bacterial virulent proteins is critical for vaccine development and understanding of virulence mechanisms in pathogens. For this purpose, a number of feature encoding methods based on sequences and evolutionary information of a given protein have been proposed and applied with some classifier algorithms so far. In this paper, we performed composition moment vector (CMV), which includes information about both composition and position of amino acid in the protein sequence to predict bacterial virulent proteins. The tests were validated in three different independent datasets. Experimental results show that CMV feature encoding method leads to better classification performance in terms of accuracy, sensitivity, f-measure and the Matthews correlation coefficient (MCC) scores on diverse classifiers. © Owned by the authors, published by EDP Sciences 2016. Source

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