Person: GÜRBÜZ, BURÇAK
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GÜRBÜZ
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BURÇAK
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Publication Metadata only Colonic delivery of compression coated nisin tablets using pectin/HPMC polymer mixture(ELSEVIER, 2007) GÜRBÜZ, BURÇAK; Ugurlu, Timucin; Turkoglu, Murat; Gurer, Umran Soyogul; Akarsu, Burcak GurbuzNisin containing pectin/HPMC compression coated tablets were prepared and their in vitro behavior tested for colonic delivery. Nisin is a 34-amino-acid residue long, heat stable peptide belonging to the group A lantibiotics with wide antimicrobial activity against Grampositive bacteria. The invention can be useful for treating colonic infectious diseases such as by Clostridium difficile, and also by colonization of vancomycin-resistant enterococci. In this study, each 100 mg core tablet of nisin was compression coated with 100% pectin, 90% pectin-10% HPMC, 85% pectin-15% HPMC, 80% pectin-20% HPMC 75% pectin-25% HPMC, 100% HPMC at a coat weight of 400 mg. The concentration and the activity of nisin were quantified using Well Diffusion Agar Assay. Drug release studies were carried out in pH 3.3 buffer solution. System degradation/erosion experiments were carried out in pH 1.2, 3.3, and 6.8 buffers using a pectinolytic enzyme. The biological activity and NMR studies were performed to assess the stability of nisin during the processing and after the in vitro tests. It was found that pectin alone was not sufficient to protect the nisin containing core tablets. At the end of the 6 h 40% degradation was observed for 100% pectin tablets. HPMC addition required to control the solubility of pectin, a 5% increase in HPMC ratio in pectin/HPMC mixture provided a 2-h lag time for nisin release. Eighty percent pectin-20% HPMC appeared to be an optimum combination for further evaluation. Tablets maintained their integrity during the 6-h dissolution test, approximating the colon arrival times. Nisin was found to be active/stable during processing and after in vitro tests. Effect of polymer hydration on pectin degradation was found to be crucial for the enzyme activity. Sufficiently hydrated pectin degraded faster. The pectin/HPMC envelope was found to be a good delivery system for nisin to be delivered to the colon. (c) 2007 Elsevier B.V. All rights reserved.Publication Metadata only FLAVONOIDS AND BIOLOGICAL ACTIVITIES OF Centaurea stenolepis(SPRINGER, 2014) ŞEN, ALİ; Sen, Ali; Gurbuz, Burcak; Gurer, Umran Soyogul; Bulut, Gizem; Bitis, LeylaPublication Metadata only Investigation of chronotherapeutic effects of amphotericin B administered to mice infected with Candida albicans(TAYLOR & FRANCIS LTD, 2013) GÜRBÜZ, BURÇAK; Tahmaz, Yesim; Cevikbas, Adile; Gurer, Umran Soyogul; Gurbuz, Burcak; Cevikbas, UgurIn this study, mice were infected with Candida albicans at 07:00 h or 19:00 h. After 24 h, the subgroups of mice received either 0.2/ml saline (as control) or one of two doses (0.5 or 1.0 mg/kg) of amphotericin B (AmB) at 0 h or 12 h for three consecutive days. A second set of uninfected mice received a single dose of either saline or AmB (5 mg/kg) at 0 h or 12 h for 4 days to study only about nephrotoxicity. For uninfected controls and AmB-treated (5 mg/kg) mice, serum blood urea nitrogen (BUN), creatinine and total protein tended to be higher at 0 h vs. 12 h, as was the histopathology score in treated mice (3.60 vs. 1.20). Serum levels changed in treated mice when compared to the control mice. The BUN levels increased whereas serum creatinine levels decreased at 12 h compared to 0 h. C. albicans colony forming units per milliliter (CFU/ml) was high in the kidneys of infected mice. Compared with the control, after treatment for 3 days with 0.5 mg AmB lowered CFU by 48% at 0 h and by 75% at 12 h. However, for the higher dose 1.0 mg AmB, CFU was lowered more or less equally at both test times: 51% at 0 h and 46% at 12 h.Publication Metadata only Synergic potential of Pelargonium endlicherianum Fenzl. Essential oil and antibiotic combinations against Klebsiella pneumoniae(ELSEVIER, 2020) GÜRBÜZ, BURÇAK; Dumlupinar, Berrak; Karatoprak, Gokce Seker; Celik, Damla Damar; Gurer, Umran Soyogul; Demirci, Betul; Gurbuz, Burcak; Rayaman, Pervin; Kurtulus, Eda MerveIn this study we investigated antimicrobial activity against Klebsiella pneumoniae and the phagocytic functions of human leukocyte cells as revealed in an in vitro experimental model combining cefepime and gentamicin with Pelargonium endlicherianum Fenzl. essential oil treatments. The bactericidal effects of this essential oil and antibiotic combinations were dynamically detected by time-kill assay. To examine the function of this essential oil and antibiotics in permeating outer membrane barriers when used singly or in combination, a UV spectrophotometer was used, and morphologic images were captured by scanning electron microscopy. The antibacterial activity of the essential oil and antibiotics was assessed using broth microdilution and agar well diffusion. The combined effects of the essential oils of P. endlicherianum and gentamicin and cefepime were evaluated by means of the checkerboard method against K. pneumoniae. In the assays, fractional inhibitory concentration (FIC) values were calculated to characterize the interactions between the combinations. In the combinations of essential oil and antibiotics, the sensitivity of the bacteria to antibiotics increased and the antibiotics had a synergistic effect, and the antibacterial effect on the microorganisms increased. The cefepime + essential oil pair tested showed a synergistic effect (FIC <= 0.5), but the gentamicin + essential oil pair did not (FIC > 0.5-4.0). Thus, the cefepime + essential oil pair has been found to exhibit a synergistic effect against K. pneumoniae compared to the gentamicin + essential oil pair. According to the results obtained here, the combined use of essential oils with antibiotics can be applied as a treatment strategy to reduce the use of antibiotics, reduce side effects, and possibly reverse antibiotic resistance to these microorganisms in light of the increase in multiple antibiotic resistance. (c) 2020 SAAB. Published by Elsevier B.V. All rights reserved.Publication Metadata only Effect of the function of polymorphonuclear leukocytes and interleukin-1 beta on wound healing in patients with diabetic foot infections(W B SAUNDERS CO LTD, 2007) GÜRBÜZ, BURÇAK; Oncul, O.; Yildiz, S.; Gurer, U. Soyogul; Yeniiz, E.; Qyrdedi, T.; Top, C.; Gocer, P.; Akarsu, B.; Cevikbas, A.; Cavuslu, S.Objectives: This study was carried out prospectively to determine the effect on prognosis of phagocytic activity index (PAI) and intracellular killing activity (IKA) of polymorphonuclear leukocytes (PMNL), and the levels of interleukin-1 beta (IL-1 beta) on prognosis in patients with diabetic foot infection (DFI). Methods: The evaluation of PAI and IKA in PMNL and the levels of IL-1 beta were performed at the beginning and in the second and fourth weeks of therapy in all diabetic patients, who were categorized into a heating group (HG) and a non-heating group (NHG) on the basis of therapy results. Results: Sixty-six cases (38 diabetic patients and 28 non-diabetic controls) were included in the study. Full recovery was observed in 23 HG patients, whereas 15 (NHG) patients were unresponsive to treatment and nine patients were subjected to amputation at the end. At the baseline, PAI, IKA and IL-1 beta levels in FIG were not significantly different compared to those of NHG, but at weeks 2 and 4, PAI and IKA levels were significantly higher and IL-1 beta levels were significantly lower than those in NHG. On the other hand, at the baseline, PAI and IKA values in HG were significantly lower and IL-1 beta levels were significantly higher in comparison with the controls. However, no significant difference was observed at week 2 or 4. Conclusion: Our results suggest that the PMNL functions and IL-1 beta regulation deteriorated in patients with DFI, and that such deteriorations might indicate inefficient therapeutic responses in patients with diabetes mellitus. (C) 2006 The British Infection Society. Published by Elsevier Ltd. ALL rights reserved.