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Öğe Benzoik asidin Vitreoscilla hemoglobin geni aktarılmış Pseudomonas aeruginosa tarafından yıkımı(Fırat Üniversitesi Fen ve Mühendislik Bilimleri Dergisi, 2005) Kahraman, Hüseyin; Geckil, HikmetÖz: Bu çalışmada, Pseudomomas aeruginosa ile onun Vitreoscilla hemoglobin geni klonlanmış rekombinant susunun önemli. endüstriyel aromatik kirleticilerden birisi olan benzoik asit yıkım yetenekleri araştırılmıştır. Pseudomonas aeruginosa ve çeşitli suşları gen transferi ve ekspresyonu gibi çalışmalarda oldukça yaygın olarak kullanılmaktadır. Bu bakterilerin, çoğu canlılar için zararlı olan birçok heterohalkasal aromatik bileşikleri doğal olarak yıkma potansiyeline sahip olmaları, onlara olan ilgiyi arttırmıştır. Bu çalışmada Vitreoscilla sp.'den elde edilen bakteriyel hemoglobin (VHb) geni (vgb) klonlanmış rekombinant bir suş (PaJC) kullanılarak, iyi bir oksijen alım sistemi olan VHb'nin bu rekombinantm benzoik asiti yıkma potansiyeline etkisi yabanıl tip konakçı bakteri ile karşılaştırmalı biçimde çalışılmıştır. Başlık (İngilizce): Degradation of benzoic acid by Pseudomonas aeruginosa engineered with Vitreoscilla hemoglobin gene Öz (İngilizce): This study is concerned with the potential use of Pseudomomas aeruginosa and its recombinant strain carrying Vitreoscilla hemoglobin gene for degradation of an important harmful aromatic compound, the benzoic acid. Pseudomonas aeruginosa and its various strains are widely known for their ease of use characteristics allowing gene transfer and expression. Moreover, a great deal of interest was paid when it was discovered that these bacteria could be utilized for the degradation of many heterocychc aromatic compounds. In this study, a recombinant strain (PaJC) of P. aeruginosa cloned with bacterial hemoglobin (VHb) gene (vgb) from Vitreoscilla sp. was studied in comparison to the wild-type host strain for its benzoic acid degradation potential.Öğe BIOCHEMICAL EFFECT EVALUATION OF MICROBIAL CHONDROITIN SULPHATE IN EXPERIMENTAL KNEE OSTEOARTHRITIS MODEL(Parlar Scientific Publications (P S P), 2022) Erenler, Ayse Sebnem; Karabulut, Aysun Bay; Sevimli, Resit; Geckil, Hikmet; Akpolat, Nusret; Unver, Tuba; Otlu, OnderOsteoarthritis (OA) is the most common chronic joint disease, primarily due to aging. Chondroitin sulfate (CS) is a glycosaminoglycan (GAG) commonly used to treat osteoarthritis. CS can delay the progression of pathology or reverse morphological changes in joint structure. Traditionally CS is produced from animal sources. However, due to different reasons such as contamination, ecological risk, and the possibility of infectious diseases, the trend towards microbial sources has increased because of its advantages such as purer, more antiallergic, and lower Molecular Weight (MW) than animal sources. Biochemical analysis of Microbial CS (MCS), which is a new and significant alternative as a source of CS in the OA healing process, has not been evaluated in the literature yet. This study was designed to analyze the biochemical effects of MCS produced by our team from a microbial source, with an MW value of 269 Daltons, on the osteoarthritis healing process compared to the commercial foiut. We aim to reach data that MCS has a higher antioxidant effect than animal -sourced CS, and in this way, it is a more suitable production for the treatment of osteoarthritis. In this study, knee osteoarthritis was surgically induced in experimental rabbits; and TGF113, CAT, MPO, TOS, and OSI parameters measured in blood samples before the operation and after the healing period were analyzed comparatively. After the surgical application, the rabbits were randomly divided into three groups: control, animal -sourced CS, and E. cull sourced. MCS. The standard rabbit diet was administered daily to 10 rabbits in Group 1 (control), and. CS and MCS were applied daily to the other groups as 17 mg/kg for 12 weeks. Blood samples were taken from rabbits at the 12th week after surgery, and TGF-113, CAT, MPO, TOS, and OSI parameters were biochemically evaluated. This study has confirmed that the antioxidant properties of MCS and data on its effectiveness in controlling oxidative stress compared to animal -sourced CS. Based on these results, it can be concluded that MCS has a significant potency of nutraceutical and therapeutic agents for OA treatment.Öğe Biological rhythm of saliva ghrelin in humans(Taylor & Francis Ltd, 2006) Aydin, Suleyman; Ozercan, H. Ibrahim; Aydin, Suna; Ozkan, Yusuf; Dagli, Ferda; Oguzoncul, Ferdane; Geckil, HikmetBackground: We previously reported that ghrelin in saliva, orexigenic hormone that induces NPY release, was produced and released by salivary glands in humans. The purpose of this study was to investigate a possible circadian rhythm in saliva ghrelin concentration in human subjects as a function of time and meal. Saliva samples were collected at three-hour intervals throughout a 24-h period in 12 healthy volunteer males and ten healthy volunteer females who were provided with meals on a fixed schedule, and saliva collections were made within 15 minutes after each meal. Saliva ghrelin levels were measured by using a commercial radioimmuno assay (RIA) kit that uses I-125-labeled bioactive ghrelin as a tracer and a rabbit polyclonal antibody raised against full-length octanoylated human ghrelin. Immunohistochemical analysis of salivary glands was also performed. The results of this investigation indicated the following. (1) The saliva ghrelin level was slightly higher in female subjects in comparison with male subjects. (2) Saliva ghrelin levels were elevated before each meal and fell to trough levels after eating. (3) Saliva ghrelin levels showed a circadian rhythm that rose throughout the day to a zenith at 0300, then dropped at 0600-0900. (4) Saliva ghrelin also weakly correlated with BMI. (5) Immunohistochemical analysis showed that ghrelin was localized in the striated and excretory ducts of salivary glands of human. The present work is the first report of the circadian rhythm of saliva ghrelin level in human subjects as a function of time and meal. Meal plays an important role in lowering saliva ghrelin concentration in humans. However, present data did not exclude whether the circadian changes in saliva ghrelin expression were regulated by the biological clock or by food intake.Öğe Bioremediation and Decolorization of Textile Dyes by White Rot Fungi and Laccase Enzymes(Springer International Publishing Ag, 2018) Yesilada, Ozfer; Birhanli, Emre; Geckil, Hikmet[Abstract Not Available]Öğe Cancer: normal cells' reply to a deadly fate(Tubitak Scientific & Technological Research Council Turkey, 2014) Mehta, Rajendra; Geckil, Hikmet; Gozuacik, Devrim[Abstract Not Available]Öğe Cloning and Expression vgb-kfo Genes in E. coli and Microbial Chondroitin Sulfate Production(Amer Scientific Publishers, 2019) Erenler, Ayse Sebnem; Geckil, Hikmet; Karabulut, Aysun Bay; Akpolat, Nusret; Sevimli, Resit; Ulke, Esra; Aliyeva, AygunThis study focused on a new plasmid and new recombinant strain developed for the production of microbial chondroitin sulfate a new and limited area of study the strategies we applied for the production of microbial chondroitin sulfate, and the possible contributions of this study to published research literature. In this study, pETM6-PACF, which carries the genes responsible for capsular chondroitin synthesis [kfA, kfoC, kfoF] was used as the basic plasmid. The Vitreoscilla hemoglobin gene region was transformed into this basic plasmid and the common expression of both gene groups was added to research literature for the first time. This plasmid was transferred to non-pathogenic E. coil (C2987) to produce a completely new chondroitin source specific to this study. Following the transformation by chondroitin synthesis, and the subsequent microbial production of chondroitin by the application of purification protocols, microbial chondroitin sulfate was produced in sulfate form. Consequently, in comparison to published literature, a product with a low molecular weight value of 269 Daltons was developed. This product, which has significant potential drug potency, can be used in many different areas as a novel and unique biomedical product.Öğe Cloning, isolation and expression of L-asparaginase gene (ansB) in different gram-negative bacteria expressing Vitreoscilla hemoglobin(Elsevier Sci Ltd, 2011) Erenler, Sebnem; Geckil, Hikmet[Abstract Not Available]Öğe Ecotoxicity of Nanomaterials in Aquatic Environment(Springer International Publishing Ag, 2020) Ozmen, Murat; Gungordu, Abbas; Geckil, Hikmet[Abstract Not Available]Öğe Effect of Vitreoscilla Hemoglobin and Culture Conditions on Production of Bacterial L-Asparaginase, an Oncolytic Enzyme(Humana Press Inc, 2014) Erenler, Sebnem O.; Geckil, Hikmetl-asparaginase is a widely used cancer chemotherapy enzyme. The source for the enzyme with this property is mainly bacterial and its synthesis is strongly regulated by oxygen. In this study, we utilized two recombinant systems: one carried the gene (vgb) for the Vitreoscilla hemoglobin (VHb), a protein of prokaryotic origin which confers a highly efficient oxygen uptake to its host and the other carried the l-asparaginase gene (ansB). The host bacteria were Escherichia coli, Enterobacter aerogenes, and Pseudomonas aeruginosa. Of these three bacteria, all gram-negative, E. coli and its recombinant strain showed up to sevenfold higher l-asparaginase activity in lactose than in other carbon sources. Although, in this bacterium glycerol was the poorest source for l-asparaginase synthesis, it supported the highest biomass production. In glucose medium, l-asparaginase activity of E. aerogenes was about threefold higher than its vgb and ansB recombinants. ansB recombinant showed significantly higher enzyme levels than both host and vgb recombinants in glycerol and lactose media. In this bacterium, VHb/vgb clearly caused a decrease in the enzyme synthesis under all conditions. As seen for E. aerogens, glycerol was the most favorable carbon source for P. aeruginosa and its vgb strain in terms of both l-asparaginase synthesis and biomass production. The cultures grown in glycerol had more than two- and threefold biomass than in glucose and lactose, respectively, and up to elevenfold than in mannitol. Indeed, the highest biomass production for all bacteria and their recombinants was in glycerol. The VHb/vgb system is clearly advantageous for production of l-asparaginase in P. aeruginosa. The same, however, does not hold true for E. aerogenes.Öğe Engineering hydrogels as extracellular matrix mimics(Future Medicine Ltd, 2010) Geckil, Hikmet; Xu, Feng; Zhang, Xiaohui; Moon, SangJun; Demirci, UtkanExtracellular matrix (ECM) is a complex cellular environment consisting of proteins, proteoglycans, and other soluble molecules. ECM provides structural support to mammalian cells and a regulatory milieu with a variety of important cell functions, including assembling cells into various tissues and organs, regulating growth and cell cell communication. Developing a tailored in vitro cell culture environment that mimics the intricate and organized nanoscale meshwork of native ECM is desirable. Recent studies have shown the potential of hydrogels to mimic native ECM. Such an engineered native-like ECM is more likely to provide cells with rational cues for diagnostic and therapeutic studies. The research for novel biomaterials has led to an extension of the scope and techniques used to fabricate biomimetic hydrogel scaffolds for tissue engineering and regenerative medicine applications. In this article, we detail the progress of the current state-of-the-art engineering methods to create cell-encapsulating hydrogel tissue constructs as well as their applications in in vitro models in biomedicine.Öğe Expression of gene encoding Theileria parva enolase in Escherichia coli JM103 strain(Elsevier Sci Ltd, 2011) Celik, Venhar; Icen, Irmak; Pelle, Roger; Munzuroglu, Omer; Geckil, Hikmet[Abstract Not Available]Öğe Genetic engineering of Theileria parva lactate dehydrogenase gene: a new anti-theilerial target(Revista Pesquisa Veterinaria Brasileira, 2018) Icen-Taskin, Irmak; Munzuroglu, Omer; Geckil, HikmetTheileria parva is the causative agent of East Coast Fever (ECF), a tick borne disease, which results in major economic losses in cattle. Major problems in dealing with this illness are the high cost of drugs, development of resistance, and absence of effective vaccines. Thus, exploiting new targets for cost effective and higher therapeutic value drugs are imperative. Glycolysis is the main pathway for generation of ATP in T. parva, given its development inside erythrocytes. Thus, the enzymes of this pathway may prove potential targets for designing new-generation anti-theilerials. Lactate dehydrogenase of T. parva (TpLDH} has the highest activity of all glycolytic enzymes and thus we selected this enzyme as the potential therapeutic target. Our study is the first to report the isolation, removal of introns through directed mutagenesis, and cloning of TpLDH and showing that amino acid insertions or deletions most notably corresponded to a 5-amino acid sequence (Asn-91A, Glu-91B, Glu-91C, Trp-91D, Asn-91E) between Ser-91 ve Arg-92 of the enzyme. This region is also present in other apicomplexan such as Babesia bovis, a pathogen of cattle and Plasmodium falciparum, a human pathogen. Providing as the attachment site for the enzyme inhibitors and not being present in LDH of respective hosts, we propose this site as an attractive drug target. The work here is expected to lead new studies on detailed structural and kinetic aspects of apicomplexan LDHs and development of new inhibitors.Öğe Investigation of some biochemical parameters of wild and culturedMyrtus communisL. fruits subjected to different conservation methods(Springer, 2021) Cakmak, Meltem; Bakar, Busra; Ozer, Dursun; Geckil, Hikmet; Karatas, Fikret; Saydam, SinanIn this study, wild and cultivated whiteMyrtus communisL. (myrtle) fruits were investigated for their vitamin levels (A, B, C and E), carotenes (lycopene, beta-carotene), functional peptides (glutathione, ghrelin), oxidative stress markers (GSSG and MDA), total phenolic and flavonoid substances, antioxidant capacity (DPPH, TEAC) and essential elements (Se, Zn, Fe, Cu and Mn). The results showed that both myrtle fruits can be considered as the good source of vitamins, antioxidants and elements. The preservation (sun or microwave-drying) methods for this seasonal fruit caused a significant (p < 0.05) decrease in their biochemical and bio-pharmacological content compared to fresh or frozen fruits. On the contrary, preservation resulted a significant increase in GSSG and MDA levels. The amounts of Se, Zn, Fe, Cu and Mn in wild myrtle fruit were found as 0.58, 205, 228.0, 37.22 and 24.3 mu g/g dw, respectively.Öğe Is ghrelin a natural anti-microbial agent?(Tubitak Scientific & Technological Research Council Turkey, 2008) Aydin, Sueleyman; Geckil, Hikmet; Kilic, Nermin; Erman, Fazilet; Kilic, Sueleyman Sirri; Yesilada, Oezfer[Abstract Not Available]Öğe Micro and nanofluidics - applications in biotechnology(Wiley-V C H Verlag Gmbh, 2011) Demirci, Utkan; Geckil, Hikmet[Abstract Not Available]Öğe Miniaturized lensless imaging systems for cell and microorganism visualization in point-of-care testing(Wiley-V C H Verlag Gmbh, 2011) Gurkan, Umut Atakan; Moon, Sangjun; Geckil, Hikmet; Xu, Feng; Wang, Shuqi; Lu, Tian Jian; Demirci, UtkanLow-cost, robust, and user-friendly diagnostic capabilities at the point-of-care (POC) are critical for treating infectious diseases and preventing their spread in developing countries. Recent advances in micro- and nanoscale technologies have enabled the merger of optical and fluidic technologies (optofluidics) paving the way for cost-effective lensless imaging and diagnosis for POC testing in resource-limited settings. Applications of the emerging lensless imaging technologies include detecting and counting cells of interest, which allows rapid and affordable diagnostic decisions. This review presents the advances in lensless imaging and diagnostic systems, and their potential clinical applications in developing countries. The emerging technologies are reviewed from a POC perspective considering cost effectiveness, portability, sensitivity, throughput and ease of use for resource-limited settings.Öğe Simultaneous quantification of acylated and desacylated ghrelin in biological fluids(Wiley, 2008) Aydin, Suleyman; Karatas, Fikret; Geckil, HikmetThis study reports simultaneous quantification of both acylated and desacylated forms of ghrelin in biological samples, utilizing a reverse-phase high-performance liquid chromatography (HPLC) system. The HPLC assay was also compared with RIA assays in use. Biological samples (serum, saliva, urine, milk) known for the presence of ghrelin were collected from a total of eight post-partum women and eight male volunteers. Analysis of ghrelin with HPLC was also validated for linearity, precision, detection limit and accuracy. An elution time of 6 min was observed for pure (commercial) desacylated human ghrelin and for the same form of the hormone from all body fluids studied. The elution time for acylated pure human ghrelin and that in body fluids, however, was around 16 min. The mean recovery rate was over 90% for both forms with no significant interference. The lowest detectable levels for acylated and desacylated ghrelin with the method used here were 11 (+/- 2) and 14 (+/- 3) pg mL(-1), respectively. Given its simplicity, accuracy, time and cost-effectiveness, the HPLC method described here for determination of two forms of ghrelin (active and inactive) might prove useful for certain diagnostic purposes. Copyright (C) 2008 John Wiley & Sons, Ltd.Öğe Triumph or tragedy: progress in cancer(Tubitak Scientific & Technological Research Council Turkey, 2014) Erenler, Ayse Sebnem; Geckil, HikmetCancer is probably the number one research area among all human endeavors, receiving the largest portion of science funding in most countries. This is because cancer remains one of the oldest conundrums among all human maladies. Although we now have a greater understanding of the biological and molecular basis of cancer, its diagnosis and therapy still pose great challenges. In this review, our aim is not to establish a comprehensive understanding of cancer, which is essentially impossible, but to outline, in a more provocative way, why cancer research in the pursuit of a cure did not live up to its promise, as the death rate from cancer has not changed much after almost half a century. In addition, we discuss some future perspectives to give some insight into cancer research and debunk the old view that pouring money into cancer research is the only way to overcome this dreadful disease.Öğe Türkiye'deki erysimum (Brassicaceae) türleri üzerinde taksonomik araştırmalar(2009) Mutlu, Birol; Geckil, Hikmet[Abstract Not Available]Öğe Vitreoscilla hemoglobin eksprasyonu yapan rekombinant bakterilerde L-DOPA ve DOPAMİN üretimi(2009) Geckil, Hikmet; Bulut, Şule; Ateş, Burhan[Abstract Not Available]
