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Öğe A sepsis case caused by a rare opportunistic pathogen: Bacillus pumilus(Ankara Microbiology Soc, 2016) Borsa, Barış Ata; Aldag, Mehmet Ersoy; Tunalı, Birsen; Dinç, Uğur; Güngördü Dalar, Zeynep; Özalp, Veli CengizThe high prevalence of Bacillus species in nature and the detection of these bacteria as contaminant in cultures may lead diagnostic dilemma, however they should still be considered as a pathogen particularly in case of repeated positive cultures from patients with risk factors. Bacillus pumilus is a bacteria, though rarely, been reported as the causative agent of various infections such as sepsis, endocarditis, skin infections and food poisoning in human. In this report, a sepsis case in an immunocompetent patient caused by B. pumilus was presented. A 38-year-old female patient was admitted to emergency service of our hospital with the complaints of headache, dizziness and diarrhea. She had not any risk factors except a history of heart valve replacement operation two years ago. In physical examination, she had abdominal retention, high fever and hypotension, together with the high levels of sedimentation rate (ESR) and C-reactive protein (CRP). The patient was hospitalized with the preliminary diagnosis of sepsis. Three sets of blood samples at two different periods were taken for the culture. All blood culture vials had a positive signal at the second day of incubation in BD BACTEC (TM) 9050 system, therefore subcultures were performed in sheep blood agar, chocolate agar and MacConkey agar, and incubated in aerobic and anaerobic conditions. Beta-haemolytic, gray-colored large colonies were isolated from anaerobic culture at the end of 18-24 hours incubation, and Gram staining from colonies showed gram-positive rods. The isolate was identified as B. pumilus with 99% accuracy rate by using BD Phoenix (TM) 100 identification system. This result was also confirmed by MALDI-TOF based VITEK (R) MS system and 16S rRNA sequencing by Illumina MiSeq (R) platform. Antibiotic susceptibility test performed by BD Phoenix (TM) 100 system and the isolate was found to be resistant against penicillin, while it was susceptible to vancomycin, erythromycin, clindamycin, levofloxacin, and trimethoprim-sulfamethoxazole. Initial treatment of patient was started with intravenous ceftriaxone and metronidazole empirically. Hypotension and fever returned to normal levels at the second and third days of the treatment, respectively. Metronidazole treatment was stopped at seventh day, and treatment was completed to 14 day with ceftriaxone alone. At the end of the treatment course, general condition of the patient was completely good, ESR and CRP were also decreased to normal levels. In conclusion, although most of the reported bloodstream infections that are caused by B. pumilus are intravascular catheter-related, artificial heart valves should also be considered as a risk factor even though vegetation was not detected in our patient.Öğe Antibiotic loaded nanocapsules functionalized with aptamer gates for targeted destruction of pathogens(Royal Soc Chemistry, 2015) Kavruk, Murat; Çelikbıçak, Ömer; Özalp, Veli Cengiz; Borsa, Barış Ata; Hernandez, Frank J.; Bayramoğlu, Gülay; Arıca, YakupIn this study, we designed aptamer-gated nanocapsules for the specific targeting of cargo to bacteria with controlled release of antibiotics based on aptamer-receptor interactions. Aptamer-gates caused a specific decrease in minimum inhibitory concentration (MIC) values of vancomycin for Staphylococcus aureus when mesoporous silica nanoparticles (MSNs) were used for bacteria-targeted delivery.Öğe Aptamer-gated silica nanoparticles synthesized via click chemistry(Amer Soc Cell Biology, 2014) Dilek, Özlem; Özalp, Veli Cengiz[No abstract available]Öğe Aptamers in medical diagnosis(Pan Stanford Publishing Pte. Ltd., 2016) Özalp, Veli Cengiz; Kavruk, Murat; Dilek, Özlem; Bayraç, Abdullah TahirAptamers have been increasingly applied in biomedical field as a class of biorecognition elements that possess many advantages such as high specificity and binding affinity, easy synthesis, easy modification, small size, non-toxicity and good stability. Many diseases like cancer exhibit cellular aberrations at morphological and molecular levels. Medical diagnosis based on molecular features can be highly specific and extremely sensitive when proper recognition molecule and an efficient signal transduction system are employed. However, bioanalysis of human diseases at the molecular level is an extremely challenging field because effective probes to identify and recognize biomarkers of diseases are not readily available. Traditional bio-recognition molecule, antibody has been exploited to develop excellent diagnosis assays in many formats, but antibodies are insufficient to match the requirements of fast and portable biosensors for point-of-care applications, which are at high demand in pathogenic bacteria detection as well as other diseases like cancer. Aptamers are short single-stranded oligonucleotides, which can be selected from random combinatorial library by SELEX in vitro. This relatively new biorecognition agent has superior intrinsic characteristics for biosensor development. In this review, we first present major aptamer selection technologies and the main formats of biosensors, which were frequently employed in aptasensor development. Then, the current state of aptamers as applied to medical diagnosis was discussed for specifically cancer and pathogen diagnosis. Finally, an overview of aptamer-nanomaterials conjugates was presented in many applications such as diagnosis, bioimaging, and theranostics.Öğe Aptamers: Molecular tools for medical diagnosis(Bentham Science Publ Ltd, 2015) Özalp, Veli Cengiz; Kavruk, Murat; Dilek, Özlem; Bayraç, Abdullah TahirAptamers have been increasingly applied in biomedical field as a class of biorecognition elements that possess many advantages such as high specificity and binding affinity, easy synthesis, easy modification, small size, non-toxicity and good stability. Many diseases like cancer exhibit cellular aberrations at morphological and molecular levels. Medical diagnosis based on molecular features can be highly specific and extremely sensitive when proper recognition molecule and an efficient signal transduction system are employed. However, bioanalysis of human diseases at the molecular level is an extremely challenging field because effective probes to identify and recognize biomarkers of diseases are not readily available. Traditional bio-recognition molecule, antibody has been exploited to develop excellent diagnosis assays in many formats, but antibodies are insufficient to match the requirements of fast and portable biosensors for point-of-care applications, which are at high demand in pathogenic bacteria detection as well as other diseases like cancer. Aptamers are short single-stranded oligonucleotides, which can be selected from random combinatorial library by SELEX in vitro. This relatively new biorecognition agent has superior intrinsic characteristics for biosensor development. In this review, we first present major aptamer selection technologies and the main formats of biosensors, which were frequently employed in aptasensor development. Then, the current state of aptamers as applied to medical diagnosis was discussed for specifically cancer and pathogen diagnosis. Finally, an overview of aptamer-nanomaterials conjugates was presented in many applications such as diagnosis, bioimaging, and theranostics.Öğe Comparison of a novel test (ODAK brucella coombs gel test) with commonly used serological tests in human brucellosis(Clin Lab Publ, 2016) Borsa, Barış Ata; Aldağ, Mehmet Ersoy; Yılmaz, Meriç; Dalar, Zeynep Güngördü; Özalp, Veli CengizBackground: Since Brucellosis is difficult to diagnose based on clinical symptoms, the diagnosis mostly relies on the results of serological testing. ODAK Brucella Coombs Gel Test is a novel and rapid gel microcolumn agglutination test which is performed in microcolumns containing gel matrix and Coombs antibodies. In this study, we aimed to compare ODAK Brucella Coombs Gel Test with other commonly used serological tests. Methods: 150 blood samples of patients, preliminarily diagnosed as Brucellosis, were included in this study. Rose Bengal (RB), ODAK Brucella Coombs Gel Test (CGT), Brucellacapt (BCAP), and Standard Agglutination Test (SAT) were performed for all samples. Also, Coombs Agglutination Test (CAT) was performed for all SAT negative samples. 1/160 and above titers were accepted as positive result except RB which is a qualitative test. Results: 100 (67%) out of 150 samples were found positive by RB. All of the 50 RB negative samples were also found negative by SAT and CAT test. However, 2 (4%) and 7 (14%) of them were positive by CGT and BCAP tests, respectively. Additionally, among 100 RB positive samples, only 68, 77, and 87 were positive by SAT+CAT combination, CGT, and BCAP tests, respectively. Conclusions: Currently, CGT is the only rapid (< 1 hour) serological test in which Coombs antibodies are used. Our results showed that negative results of RB, as a screening test, are not reliable enough as compared to CGT. However, positive RBT results confirmed with SAT were almost always, in most of the cases with higher titers, positive with CGT and BCAP. On the other hand, even if SAT is found negative with RB positivity, samples still must be investigated with CAT, CGT or BCAP. Consequently, CGT may be used as a rapid screening test instead of RB and it furthermore has similar sensitivity with the other confirmation tests in which Coombs antibodies are used. Therefore, ODAK Brucella Coombs Gel Test seems to be a very useful diagnostic tool for Brucellosis.Öğe DNA Aptamers are functional molecular recognition sensors in protic Ionic liquids(Wiley-V C H Verlag Gmbh, 2014) Machado, Isabel; Özalp, Veli Cengiz; Rezabal, Elixabete; Schaefer, ThomasThe function and structural changes of an AMP molecular aptamer beacon and its molecular recognition capacity for its target, adenosine monophosphate (AMP), was systematically explored in solution with a protic ionic liquid, ethylammonium nitrate (EAN). It could be proven that up to 2 M of EAN in TBS buffer, the AMP molecular aptamer beacon was still capable of recognizing AMP while also maintaining its specificity. The specificity was proven by using the guanosine monophosphate (GMP) as target; GMP is structurally similar to AMP but was not recognized by the aptamer. We also found that in highly concentrated EAN solutions the overall amount of double stranded DNA formed, as well as its respective thermal stability, diminished gradually, but surprisingly the hybridization rate (k(h)) of single stranded DNA was significantly accelerated in the presence of EAN. The latter may have important implications in DNA technology for the design of biosensing and DNA-based nanodevices in nonconventional solvents, such as ionic liquids.Öğe DNA-aptamer gating membranes(Royal Soc Chemistry, 2015) Schaefer, Thomas; Özalp, Veli CengizThis report describes a membrane barrier whose permeability is modulated through the recognition of a small-molecule target, adenosine triphosphate (ATP), by a DNA-aptamer. The gating function of the DNA-aptamer in the stimulus-responsive membrane was shown to be specific, concentration dependent, and reversible.Öğe Examination of fabrication conditions of acrylate-based hydrogel formulations for doxorubicin release and efficacy test for hepatocellular carcinoma cell(Taylor & Francis Ltd, 2014) Bayramoğlu, Gülay; Gözen, Damla; Ersoy, Gözde; Özalp, Veli Cengiz; Akçalı, K. Can; Arıca, M. YakupThe objective of the present study was to develop 2-hydroxypropyl methacrylate-co-polyethylene methacrylate [p(HPMA-co-PEG-MEMA)] hydrogels that are able to efficiently entrap doxorubicin for the application of loco-regional control of the cancer disease. Systemic chemotherapy provides low clinical benefit while localized chemotherapy might provide a therapeutic advantage. In this study, effects of hydrogel properties such as PEG chains length, cross-linking density, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery. In addition, the characterization of the hydrogel formulations was conducted with swelling experiments, permeability tests, Fourier transform infrared, SEM, and contact angle studies. In these drug-hydrogel systems, doxorubicin contains amine group that can be expected a strong Lewis acid-base interaction between drug and polar groups of PEG chains, thus the drug was released in a timely fashion with an electrostatic interaction mechanism. It was observed that doxorubicin release from the hydrogel formulations decreased when the density of cross-linking, and drug/polymer ratio were increased while an increase in the PEG chains length of the macro-monomer (i.e. PEG-MEMA) in the hydrogel system was associated with an increase in water content and doxorubicin release. The biocompatibility of the hydrogel formulations has been investigated using two measures: cytotoxicity test (using lactate dehydrogenase assay) and major serum proteins adsorption studies. Antitumor activity of the released doxorubicin was assessed using a human SNU398 human hepatocellular carcinoma cell line. It was observed that doxorubicin released from all of our hydrogel formulations which remained biologically active and had the capability to kill the tested cancer cells.Öğe Fibrous polymer grafted magnetic chitosan beads with strong poly(cation-exchange) groups for single step purification of lysozyme(Elsevier Science Bv, 2015) Bayramoğlu, Gülay; Tekinay, Turgay; Özalp, Veli Cengiz; Arıca, M. YakupLysozyme is an important polypetide used in medical and food applications. We report a novel magnetic strong cation exchange beads for efficient purification of lysozyme from chicken egg white. Magnetic chitosan (MCHT) beads were synthesized via phase inversion method, and then grafted with poly(glycidyl methacrylate) (p(GMA)) via the surface-initiated atom transfer radical polymerization (SI-ATRP). Epoxy groups of the grafted polymer, were modified into strong cation-exchange groups (i.e., sulfonate groups) in the presence of sodium sulfite. The MCTH and MCTH-g-p(GMA)-SO3H beads were characterized by ATR-FTIR, SEM, and VSM. The sulphonate groups content of the modified MCTH-g-p(GMA)-4 beads was found to be 0.53 mmol g(-1) of beads by the potentiometric titration method. The MCTH-g-p(GMA)-SO3H beads were first used as an ion-exchange support for adsorption of lysozyme from aqueous solution. The influence of different experimental parameters such as pH, contact time, and temperature on the adsorption process was evaluated. The maximum adsorption capacity was found to be 208.7 mg g(-1) beads. Adsorption of lysozyme on the MCTH-g-p(GMA)-SO3H beads fitted to Langmuir isotherm model and followed the pseudo second-order kinetic. More than 93% of the adsorbed lysozyme was desorbed using Na2CO3 solution (pH 11.0). The purity of the lysozyme was checked by HPLC and SDS gel electrophoresis. In addition, the MCTH-g-p(GMA)-SO3H beads prepared in this work showed promising potential for separation of various anionic molecules. (C) 2015 Elsevier B.V. All rights reserved.Öğe Hedefe Yönelik Aptamer-İlaç Konjugatı: Kanser Tedavisinde Hücre İçine Selektif İlaç Taşınması ve Dual İnhibitör Etki(2018) Altıok, Nedret; Özalp, Veli CengizBu projede, yüksek oranda HER2 ekspresyonu bulunan meme kanser hücreleri, MDA MB 453 ve SKBR3, kullanarak Hücre-SELEX yöntemi ile HER2 reseptörünü hedef alan yeni bir DNA aptamer sentezledik. Aptamerlerin bağlanma ve hücre içine alınmasını spektroskopik ve optikal yöntemle LI-COR® Odyssey® Infrared Imaging Systemi kullanarak izleyebilmek için yakın kızılötesi (NIR) IRDye 800 boyası HER2 aptamer dizilerinin 5? uçlarına bağlandı. Dizilemeden sonra elde edilen 10 aday aptamer dizisinin HER2 reseptörlerine bağlanma affiniteleri yakın kızılötesi optikal görüntüleme kullanılarak hücrelerdeki fluoresan yoğunlukları ölçülerek analiz edildi. Bir aptamer dizisinin, HMAP7 (41 nt), hücreye bağlanma affinitesi ve spesifitesi Hücre-SELEX ?ten elde ettiğimiz diğer aptamer dizilerinden 2-8 kat daha yüksek bulundu. Ayrıca, HMAP7?nin bağlanma özelliklerini, daha önce iki grup tarafından yayınlanmış HER2 hedefli DNA aptamerler ile karşılaştırdığımızda bir aptamer dizisi ile hiç bağlanma görmezken diğeri ile HMAP7?ye göre 8 kat daha az bağlanma saptadık. HMAP7, aşırı HER2 ekspresyonu bulunan meme kanser hücrelerine spesifik ve kompetitif şekilde bağlandıktan sonra, hücrelerin içine alındı, fakat hiç HER2 ekspresyonu olmayan MDA MB 231 hücrelerine bağlanmadı. İlginç olarak, HMAP7, MDA MB 453 hücrelerine konstitutif olarak aktif HER2 reseptörleri bulunan SKBR3 hücrelerinden daha yüksek afinite ile bağlandı. Daha sonra, sitotoksik ilaç paklitakse?li hedefe yönelik bir şekilde taşımak için HMAP7-paklitaksel konjugatı sentezleyerek HER2 aşırı ekspresyonu olan meme kanser hücrelerinde hücre proliferasyonu ve ölümü üzerine etkilerini araştırdık, fakat HMAP7-paklitaksel konjugatı ile tek başına paklitaksel?in etkileri arasında belirgin bir fark göremedik. Bunun nedeni, paklitaksel?in üç hücrede de düşük nanomolar konsantrasyonlarda hücre ölümüne yol açması ve uzun süreli inkübasyonda aptamerin nükleazlar tarafından degrade edilmesi olabilir. Bu bulgular, bu çalışmada seçilen HER2 reseptörlerini hedefleyen DNA aptamer HMAP7?nin görüntüleme veya terapötik ajanların HER2-pozitif meme tümörlerine taşınmasında yeterince selektif olduğunu göstermiştir, fakat fonksiyonel olabilmesi için HMAP7?nin modifikasyonu gerekecektirÖğe Immobilized lipase on micro-porous biosilica for enzymatic transesterification of algal oil(Inst Chemical Engineers, 2015) Bayramoğlu, Gülay; Akbulut, Aydın; Özalp, Veli Cengiz; Arıca, M. YakupEnzymatic transesterification reactions for biodiesel production require harsh conditions, which require methods of enzyme stability enhancements. In this study, we present covalently immobilized lipase on the biosilica-polymer composite as a viable method to obtain enzymes with enhanced stability in such harsh conditions. The fresh water microalgae Scenedesmus quadricauda was cultivated in a batch photo-bioreactor with CO2 aeration, and urea was supplied as nitrogen source (0.075 g L-1). Under optimized conditions, the amount of extracted oil was around 29.6%. Finally, the algal oil was utilized for production of biodiesel via enzymatic transesterification reaction which were performed in n-hexane using the free and immobilized lipase preparations. Fatty acid methyl ester (FAME) components were determined using gas chromatography-mass spectrophotometry (GC-MS). The conversion of algal oil to biodiesel was found to be 85.7% and 96.4%, with the free and immobilized enzyme, respectively. The immobilized lipase was highly stable and only 17% of activity was lost after 6 cycles repeated uses. (c) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe Improvement stability and performance of invertase via immobilization on to silanized and polymer brush grafted magnetic nanoparticles(Elsevier Sci Ltd, 2017) Bayramoğlu, Gülay; Doz, Tuğce; Özalp, Veli Cengiz; Arıca, M. YakupIn this study, magnetic nanoparticles (Fe3O4) were modified sequentially with silica (Fe3O4@SiO2), glycidyl methacrylate (GMA) by surface initiated atom transfer radical polymerization (SI-ATRP) and hexamethylene diamine (as a spacer arm). The p(GMA) grafted and SA modified form (i.e., Fe3O4@SiO2@pGMA-SA-3) was used for covalent immobilization of invertase (EC 3.2.1.26). The amount of immobilized enzyme on Fe3O4@SiO2@p(GMA) and Fe3O4@SiO2@p(GMA)-SA-3 was 36.1 +/- 0.9 and 33.4 +/- 1.3 mg/g, respectively. The K-m and V-max values of immobilized invertase were found to be 39.4 mmol/L and 349.5 mmol/L min, and not significantly changed compared with free form (34.3 mmol/L and 387.2 mmol/L min), respectively, revealed that the applied protocol did not have any detrimental effect on the retained activity of immobilized invertase. (C) 2016 Elsevier Ltd. All rights reserved.Öğe In situ monitoring of DNA-aptavalve gating function on mesoporous silica nanoparticles(Wiley-V C H Verlag Gmbh, 2014) Özalp, Veli Cengiz; Pinto, Alessandro; Nikulina, Elizaveta; Chuvilin, Andrey; Schaefer, ThomasMesoporous silica nanoparticles have proved to be efficient stimuli-responsive controlled release systems for drug delivery when functionalized with nanovalves. Nucleic acid aptamers have recently been adapted to function as novel nanovalves, so-called aptavalves, with molecular-recognition capabilities and target concentration-dependent actuation in nanopore-controlled drug delivery and membrane separation systems. The working mechanism of aptavales relies on their structural rearrangement triggered by a specific target molecule. As a consequence, a controlled and concentration-dependent release of payload occurs rendering this system particularly appealing for therapeutic applications. However, straightforward monitoring techniques are necessary in order to elucidate the function of aptavalves in situ and varying experimental conditions. Here, the structure-switching mechanical movements of an ATP-responsive aptavalve on the surface of mesoporous silica are characterized in real-time and in situ using circular dichroism (CD). The experimental data obtained on the aptavalve actuation are in excellent agreement with the payload release kinetics determined by fluorescence measurements. It is shown that CD serves as a reliable real-time analysis of the function of aptalvalves, and that the results obtained obey furthermore standard controlled release models. This allows in principle to pre-determine the release rate of the modified silica particles according to particular application requirements.Öğe Inhibitory effects of aptamer targeted teicoplanin encapsulated PLGA nanoparticles for Staphylococcus aureus strains(Springer, 2020) Uçak, Samet; Sudağıdan, Mert; Borsa, Barış Ata; Mansuroğlu, Banu; Özalp, Veli CengizEmergence of resistance to traditional antibiotic treatments necessitates alternative delivery systems. Teicoplanin is a glycopeptide antibiotic used in the treatments of serious infections caused by Gram-positive bacteria, including Methicillin Resistant Staphylococcus aureus (MRSA). One strategy to keep up with antibiotic resistance development is to limit dose and amount during treatments. Targeted delivery systems of antibiotics have been suggested as a mechanism to slow-down the evolution of resistance and to increase efficiency of the antimicrobials on already resistant pathogens. In this study, we report teicoplanin delivery nanoparticles of Poly Lactic-co-Glycolic Acid (PLGA), which are functionalized with S. aureus specific aptamers. A 32-fold decrease in minimum inhibitory concentration (MIC) values of teicoplanin for S. aureus was demonstrated for susceptible strains and about 64-fold decline in MIC value was achieved for moderately resistant clinical isolates of MRSA upon teicoplanin treatment with aptamer-PLGA nanoparticles. Although teicoplanin delivery in PLGA nanoparticles without targeting demonstrated eightfold decrease in MIC of susceptible strains of S. aureus and S. epidermidis and twofold in MIC of resistant strains, the aptamer targeting specifically decreased MIC for S. aureus, but not for S. epidermidis. Therefore, aptamer-targeted PLGA delivery of antibiotic can be an attractive alternative to combat with some of the multi-drug resistant bacterial pathogens.Öğe Investigation of isepamicin, chloramphenicol and minocycline sensitivity in carbapenem-resistant enterobacteriaceae(Aves, 2018) Karakullukçu, Asiye; Borsa, Barış Ata; Kuşkucu, Mert Ahmet; Bakır, Esra; Taner, Zeynep; Özalp, Veli Cengiz; Aygun, GökhanObjective: In this study, we aimed to determine the resistance mechanisms of carbapenem-resistant Enterobacteriaceae (CRE), and evaluate the prospective alternative treatment options. Methods: Between October 2014 and July 2015, rectal swabs routinely obtained from hospitalized patients were included in the study. The isolated Gram-negative enteric bacteria were identified to the species level by using standard conventional microbiological methods. Determined carbapenem resistance in enteric bacteria was confirmed by using meropenem Etest (R) (bioMerieux, Marcy l'Etoile, France), and the resistance mechanisms were investigated with MAST-ID (TM) Discs (Mast Diagnostics Ltd, Bootle, Merseyside, UK). Antibiotic susceptibilities of the CRE were determined by disk diffusion method using isepamicin, chloramphenicol, and minocycline disks (Oxoid, Basingstoke, Hampshire, UK). Results: Of the 3,323 rectal swabs sent to the laboratory during the study period, totally 84 (2.5%) CRE were isolated with one strain from each patient. Of the 84 CRE, 74 (88%) were Klebsiella pneumoniae and 10 (12%) were Escherichia coli. Among the 84 CRE, 66 (78.5%) with OXA-48, 11 (13.1%) with OXA48 + metallo-beta-lactamase (MBL), 1 (1.2%) with only MBL and 1 (1.2%) with AmpC + porin loss were detected, none of the strains were positive for KPC. In 5 (6%) strains, none of the resistance mechanisms were found. Of the 84 CRE, 80 (95.2%), 77 (91.6%) and 14 (16.6%) were found to be susceptible to isepamicin, chloramphenicol and minocycline, respectively. Conclusions: The OXA-48 type, endemic in Turkey, was also the most commonly detected carbapenemase in the study. It has been observed that isepamicin and chloramphenicol can be the potential antibiotics in the treatment of KDE-related infections.Öğe Karbapeneme Dirençli Enterik Bakterilerde İsepamisin, Kloramfenikol ve Minosiklin Duyarlılığının Araştırılması(2018) Karakullukçu, Asiye; Borsa, Barış Ata; Kuşkucu, Mert Ahmet; Bakır, Esra; Taner, Zeynep; Özalp, Veli Cengiz; Aygün, GökhanAmaç: Bu çalışmada, karbapeneme dirençli enterik bakteri(KDE)’lerin direnç özelliklerinin belirlenmesi ve ileriye yönelikalternatif tedavi seçeneklerinin değerlendirilmesi amaçlanmıştır.Yöntemler: Ekim 2014-Temmuz 2015 tarihleri arasında, yatanhastalardan rutin olarak elde edilen rektal sürüntü örnekleriçalışmaya alındı. İzole edilen enterik bakteriler standard konvansiyonelmikrobiyolojik yöntemlerle idantifiye edildi. Saptanankarbapenem direnci meropenem Etest® (bioMérieux,Marcy l'Etoile, Fransa) yöntemiyle doğrulanıp, direnç mekanizmalarıMAST-ID™ Discs (Mast Diagnostics Ltd, Bootle,Merseyside, Birleşik Krallık) karbapenemaz aktivite testdiskleriyle araştırıldı. Kökenlerin duyarlılıkları, disk difüzyonyöntemiyle isepamisin, kloramfenikol ve minosiklin diskleri(Oxoid, Basingstoke, Hampshire, Birleşik Krallık) kullanılarakdeğerlendirildi.Bulgular: Çalışma dönemi içerisinde laboratuvara gönderilen3323 rektal örnekten, her hastaya ait bir köken olmak üzere toplam84 (%2.5) KDE izole edildi. Bu kökenlerin 74 (%88)'ü Klebsiellapneumoniae ve 10 (%12)'u Escherichia coli idi. Kökenlerin66 (%78.5)’sında OXA-48, 11 (%13.1)’inde OXA-48 + metallo-β-laktamaz (MBL), 1 (%1.2)’inde sadece MBL, 1 (%1.2)’inde sadeceAmpC + porin kaybı saptanırken, hiçbirinde KPC pozitifliğisaptanmadı; 5 (%6)'inde ise test edilen direnç mekanizmalarındanhiçbirine rastlanmadı. Toplam 84 KDE'nin 80 (%95.2)’iisepamisine, 77 (%91.6)’si kloramfenikole ve 14 (%16.6)’ü minosiklineduyarlı olarak saptandı.Sonuçlar: Türkiye'de endemik olan OXA-48 tipi, çalışmada daen çok tespit edilen karbapenemaz oldu. KDE'lere bağlı infekÖzgün siyonların tedavisinde isepamisin ve kloramfenikol gündemegelebilecek antibiyotikler olabilir.Klimik Dergisi 2018; 31(1): 50-5.Öğe Kerstersia gyiorum: An unusual pathogen causing chronic suppurative otitis media(Aves, 2017) Borsa, Barış Ata; Kaplan, Hasan Hayri; Bayri-Barış, Ayşe; Güngördü-Dalar, Zeynep; Özalp, Veli CengizChronic suppurative otitis media was diagnosed in a 30-year old female with left ear pain and ear discharge lasting since 5 years intermittently. Lactose-negative, oxidase-negative, Gram-negative small bacilli grown as flat and gray colonies with smooth margins were identified as Kerstersia gyiorum by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rRNA analysis. Minimum inhibitory concentration values were determined by broth microdilution method (ciprofloxacin >2 mu g/mL, ertapenem <0.25 mu g/mL, imipenem 0.5 mu g/mL, ceftazidime 2 mu g/mL, amikacin <= 4 mu g/mL, ceftriaxone <= 0.5 mu g/mL, gentamicin 2 mu g/mL and tigecycline 1 mu g/mL). It was learned that her clinical findings resolved by oral amoxycillin-clavulanic acid and topical ciprofloxacin given empirically.Öğe Label-free lateral flow assay for Listeria monocytogenes by aptamer-gated release of signal molecules(Academic Press Inc Elsevier Science, 2019) Taşbaşı, B. Büşra; Güner, Buket C.; Sudağıdan, Mert; Uçak, Samet; Kavruk, Murat; Özalp, Veli CengizLateral flow assay (LFA) type of biosensors have been popular due to cost-effectiveness and easy-interpretation for instant results, most common examples of applications being pregnancy tests, food safety or medical diagnostics. There are several examples of reports with high sensitivity, including pre-concentration of the sample by magnetic pull-down. However, sensitivity and direct detection designs with aptamers has been a limiting factor for developing aptamers-based LFA assays. In this study, we report a lateral flow design based on aptamer-gated silica nanoparticles to develop high sensitivity and direct bacterial assay by shifting aptamers-target interaction to conjugation pad. Aptamer-gated silica nanoparticles-based biosensors were reported for their high sensitivity, specificity and label-free detection for small molecules and whole cells. This label-free strategy for LFA can determine L. monocytogenes in minced chicken matrix at less than 5 min with a limit of detection (LOD) of 53 cells in one mL samples.Öğe Magnetic polymeric beads functionalized with different mixed-mode ligands for reversible immobilization of trypsin(Amer Chemical Soc, 2014) Bayramoğlu, Gülay; Özalp, Veli Cengiz; Arica, M. YakupIn this study, we describe a preparation of magnetic affinity support carrying different ligands for immobilization of trypsin via adsorption. The magnetic support was synthesized in the bead form using glycidylmethacrylate (GMA) and methylmethacrylate (MMA) monomers. Three different ligands (i.e., p-aminobenzoic acid, L-phenylalanine and p-aminobenzamidine,) were attached on the aminated magnetic beads surface via glutaraldhyde coupling. Specific surface area of the mp(GMA/MMA) beads was found to be 21.4 m(2)/g. The maximum trypsin adsorption was observed at pH 7.0 for p-aminobenzoic acid and L-phenylalanine and at pH 8.0 for p-aminobenzamidine carrying ligand. The maximum amounts of the enzyme adsorbed on the p-aminobenzoic acid-, L-phenylalanine-, and p-aminobenzamidine-attached magnetic beads reached 99.6, 84.2, and 75.9 mg/g with an enzyme activity recovery of 69.4, 73.2, and 22.9%, respectively. The L-phenylalanine ligand-attached support displayed a higher activity recovery than those of the p-aminobenzoic acid- and the p-aminobenzamidine-attached magnetic beads. This carrier showed also very good storage and operational stability. Trypsin immobilized on p-aminobenzoic acid showed significant activity toward casein. Trypsin could be repeatedly adsorbed and desorbed with all of the ligand-attached beads without a noticeable loss in the adsorption capacity.
