Person: OGAN, AYŞE
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OGAN
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AYŞE
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Publication Metadata only Preparation and drug release properties of lignin-starch biodegradable films(WILEY-V C H VERLAG GMBH, 2012) OGAN, AYŞE; Calgeris, Ilker; Cakmakci, Emrah; Ogan, Ayse; Kahraman, M. Vezir; Kayaman-Apohan, NilhanStarch is one of the most commonly available natural polymers which are obtained from agro-sources. It is renewable and abundant in nature. Unfortunately due to its poor mechanical properties and hygroscopic nature, there are some strong limitations to the development of starch-based products. Usually blends of starch are prepared and plasticized with glycerol to improve some of its properties. In this study, lignin was extracted from hazelnut shells and investigated as a potential additive for starch biofilms. The structural characterization of hazelnut lignin was performed by employing UV spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Lignin was blended with corn starch in different ratios to obtain biofilms. Mechanical and thermal properties of the biofilms were enhanced as the lignin amount was increased in the formulations. Water absorption tests were performed at pH 2.0, 4.0, and 6.0. The percent swelling values of the starch/lignin films increased as pH increased. Also, the biofilm exhibiting the best properties was chosen for the drug release studies. Biofilms showed a fast ciprofloxacin (CPF) release within an hour and then the drug release rate decreased. A pH dependent drug release mechanism was also observed according to KoshnerPeppas model. The drug release increased with a decrease in pH.Publication Metadata only Soybean oil based resin: A new tool for improved immobilization of alpha-amylase(WILEY, 2006) OGAN, AYŞE; Kahraman, MV; Kayaman-Apohan, N; Ogan, A; Gungor, AAcrylated epoxidized soybean resin has been utilized to immobilize the alpha-amylase via UV-curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. (c) 2006 Wiley Periodicals, Inc.Publication Open Access Alterations in the kinetic activity of aromatlc-L-amino acid decarboxylase and preliminary 2-DE investigation of the brains in a 6-OHDA induced Parkinson's disease rat model(2003-07-01) OGAN, AYŞE; ONAT, FİLİZ; GÜLHAN, REZZAN; Günel A., OGAN A., ONAT F., GÜLHAN R.Objective: The aim of this study was to isolate and purify the aromatic-L-amino acid decarboxylase (AADC,EC 4.1.1.28) enzyme rats from Parkinson\"s Disease (PD) induced and the healthy control group rat brains and compare the alterations in the kinetic activities of the isolated enzyme. The protein spots displaying on the 2-DE patterns of the diseased and the healthy control group crude rat brain homogenates were evaluated. Medhods: In this study, the Parkinson\"s Disease model was induced by injecting 6-hydroxydopamine into the brains of the rats. The PD model formation was successful in two rats out of three. Results: The AADC decarboxylase was isolated and partially purified by DEAE-Sephacel ion exchange chromatography from the brains of PD induced and healthy control animals to compare the kinetic activity of the enzyme. The kinetic activity of the enzyme was reduced 70% in the PD group compared to controls. In order to determine and correlate the alterations with PD, and the distribution of the proteins displayed by the crude brain homogenates of the diseased and the healthy control group both were investigated. Polyacrylamide gel electrophoresis (PAGE) of the crude brain homogenates under the native and denaturizing conditions displayed matching bands for both of the groups, while two dimensional electrophoresis (2-DE) patterns of the crude brain homogenates of the diseased and the control group displayed considerable differences. Conclusion: The results of this study confirm the power of 2-DE-PAGE technique of the proteome analysis. Currently only the proteome analysis enables the identification of disease correlated proteins.Publication Metadata only İnsan monoamin oksidaz a ve b inhibitörleri olarak benzokumarin türevlerinin sentezi ve biyolojik olarak değerlendirilmesi(2015-05-07) DANIŞ, ÖZKAN; DEMİR, SERAP; OGAN, AYŞE; ERDEM, SAFİYE; Danış Ö., Yüce Dursun B., Demir S., Alparslan M., Ogan A., Erdem S.Publication Metadata only Preparation and characterization of sol-gel hybrid coating films for covalent immobilization of lipase enzyme(ELSEVIER, 2016) OGAN, AYŞE; Yuce-Dursun, Basak; Cigil, Asli Beyler; Dongez, Dilek; Kahraman, M. Vezir; Ogan, Ayse; Demir, SerapIn this study UV-curable hybrid epoxy-silica polymer films were prepared via sol-gel method. Lipase (EC 3.1.1.3) from Candida rugosa was covalently immobilized onto hybrid epoxy-silica polymer films and immobilization capacity of polymer films was found 7.22 mg g(-1). The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Immobilized and free enzymes were used in two different reaction systems: hydrolysis of p-nitrophenyl palmitate in aqueous medium and synthesis of p-nitrophenyl linoleate (from p-nitrophenol and linoleic acid) in n-hexane medium. The effect of temperature on hydrolytic and synthetic activities was investigated and observed maximum activities at 50 degrees C and 45 degrees C for immobilized enzyme, orderly. Km values for free enzyme were determined 0.71 and 1.12 mM by hydrolytic and synthetic activity assays, respectively, while these values were observed as 0.91 mM and 1.19 mM for immobilized enzyme. At the end of 30 repeated cycles, 56% and 59% of initial activities remained for hydrolytic and synthetic assays, respectively. Native enzyme lost its activity completely within 20 days, whereas the immobilized enzyme retained for hydrolytic and synthetic activities was approximately 82% and 72%, respectively, under the same storage time. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only Anne sütünden insülin benzeri büyüme faktörü-I (igf-I) bağlayıcı proteinlerin ligand blot metodu ile analizi(2002-06-24) OGAN, AYŞE; Yeldan M., Ogan A.Publication Open Access Spectrophotometric determination of leukocytes in urine(WILEY, 2004) OGAN, AYŞE; Imren-Eryilmaz, E; Kuzu-Karsilayan, H; Ogan, AA spectrophotometric method based on myeloperoxidase activity for the determination of leukocytes in urine is described. Red cells that may be found in urine samples were lysed by an ammonium chloride method. Leukocytes were then sedimented by centrifugation and lysed using Triton X-100 (Sigma Chemicals Co., St. Louis, MO). Myeloperoxidase-catalyzed oxidation of o-dianisidine was carried out at 37degreesC, pH 7. The reaction was stopped with the addition of 2 M H2SO4, and a stable form of oxidized o-dianisidine in acidic solution was obtained. Solid particles that may be found in urine samples were removed by centrifugation to avoid turbidity, and absorbance values of the supernatants were recorded at 400 rim. An Average number of leukocytes were noted per number of fields by microscopic examination and were related with the absorbance values of the supernatants at 400 nm. Pearson correlation (r) between our presented spectrophotometric analysis results and visual microscopic analysis was 0.877. Roche Combur 10-test M strips (Roche, Mannheim, Germany) and Multistix 10 SG Bayer test strips (Bayer Diagnostics, UK) were 0.645 and 0.648, respectively (P < 0.0001). (C) 2004 Wiley-Liss, Inc.Publication Metadata only Preparation, characterization, and in vitro evaluation of isoniazid and rifampicin-loaded archaeosomes(WILEY, 2018) OGAN, AYŞE; Attar, Azade; Bakir, Ceren; Yuce-Dursun, Basak; Demir, Serap; Cakmakci, Emrah; Danis, Ozkan; Birbir, Meral; Ogan, AyseThe ability of Archaea to adapt their membrane lipid compositions to extreme environments has brought in archaeosomes into consideration for the development of drug delivery systems overcoming the physical, biological blockades that the body exhibits against drug therapies. In this study, we prepared unilamellar archaeosomes, from the polar lipid fraction extracted from Haloarcula 2TK2 strain, and explored its potential as a drug delivery vehicle. Rifampicin and isoniazid which are conventional drugs in tuberculosis medication were loaded separately and together in the same archaeosome formulation for the benefits of the combined therapy. Particle size and zeta potential of archaeosomes were measured by photon correlation spectroscopy, and the morphology was assessed by with an atomic force microscope. Encapsulation efficiency and loading capacities of the drugs were determined, and in vitro drug releases were monitored spectrophotometrically. Our study demonstrates that rifampicin and isoniazid could be successfully loaded separately and together in archaeosomes with reasonable drug-loading and desired vesicle-specific characters. Both of the drugs had greater affinity for archaeosomes than a conventional liposome formulation. The results imply that archaeosomes prepared from extremely halophilic archaeon were compatible with the liposomes for the development of stable and sustained release of antituberculosis drugs.Publication Metadata only Changes in intracellular protein expression in cortex., thalamus and hippocampus in a genetic rat model of absence epilepsy(PERGAMON-ELSEVIER SCIENCE LTD, 2011) OGAN, AYŞE; Danis, Ozkan; Demir, Serap; Gunel, Aslihan; Aker, Rezzan Gulhan; Gulcebi, Medine; Onat, Filiz; Ogan, AyseEpilepsy is a chronic disorder characterized by repeated seizures resulting from abnormal activation of neurons in the brain. Although mutations in genes related to Na+, K+, Ca2+ channels have been defined, few studies show intracellular protein changes. We have used proteomics to investigate the expression of soluble proteins in a genetic rat model of absence epilepsy Genetic Absence Epilepsy Rats from Strasbourg (GAERS). The advantage of this technique is its high throughput quantitative and qualitative detection of all proteins with their post-translational modifications at a given time. The parietal cortex and thalamus, which are the regions responsible for the generation of absence seizures, and the hippocampus, which is not involved in this activity, were dissected from GAERS and from non-epileptic control rat brains. Proteins from each tissue sample were isolated and separated by two-dimensional gel electrophoresis. Spots that showed significantly different levels of expression between controls and GAERS were identified by nano LC-ESI-MS/MS. Identified proteins were: ATP synthase subunit delta and the 14-3-3 zeta isoform in parietal cortex; myelin basic protein and macrophage migration inhibitory factor in thalamus; and macrophage migration inhibitory factor and 0-beta 2 globulin in hippocampus. All protein expressions were up-regulated in GAERS except 0-beta globulin. These soluble proteins are related to energy generation, signal transduction, inflammatory processes and membrane conductance. These results indicate that not only membrane proteins but also cytoplasmic proteins may take place in the pathophysiology and can be therapeutic targets in absence epilepsy. (C) 2011 Elsevier Inc. All rights reserved.Publication Open Access Covalent immobilization of acetylcholinesterase on a novel polyacrylic acid-based nanofiber membrane(WILEY, 2018-04) OGAN, AYŞE; Cakiroglu, Bekir; Cigil, Asli Beyler; Ogan, Ayse; Kahraman, M. Vezir; Demir, SerapIn this study, polyacrylic acid-based nanofiber (NF) membrane was prepared via electrospinning method. Acetylcholinesterase (AChE) from Electrophorus electricus was covalently immobilized onto polyacrylic acid-based NF membrane by demonstrating efficient enzyme immobilization, and immobilization capacity of polymer membranes was found to be 0.4 mg/g. The novel NF membrane was synthesized via thermally activated surface reconstruction, and activation with carbonyldiimidazole upon electrospinning. The morphology of the polyacrylic acid-based membrane was investigated by scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and thermogravimetric analysis. The effect of temperature and pH on enzyme activity was investigated and maxima activities for free and immobilized enzyme were observed at 30 and 35 degrees C, and pH 7.4 and 8.0, respectively. The effect of 1 mM Mn2+, Ni2+, Cu2+, Zn2+, Mg2+, Ca2+ ions on the stability of the immobilized AChE was also investigated. According to the Michaelis-Menten plot, AChE possessed a lower affinity to acetylthiocholine iodide after immobilization, and the Michaelis-Menten constant of immobilized and free AChE were found to be 0.5008 and 0.4733 mM, respectively. The immobilized AChE demonstrated satisfactory reusability, and even after 10 consecutive activity assay runs, AChE maintained ca. 87% of its initial activity. Free enzyme lost its activity completely within 60 days, while the immobilized enzyme retained approximately 70% of the initial activity under the same storage time. The favorable reusability of immobilized AChE enables the support to be employable to develop the AChE-based biosensors.