Browsing by Author "Yazihan, Nuray"

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    Bacterial hyaluronic acid production through an alternative extraction method and its characterization
    (2019) Gungor, Gokhan; Gedikli, Serap; Toptas, Yagmur; Akgun, Dilber E.; Demirbilek, Murat; Yazihan, Nuray; Celik, Pinar Aytar; Denkbas, Emir B.; Cabuk, Ahmet
    BACKGROUND In this study, hyaluronic acid (HA) was produced using Streptococcus equi ssp. equi via an optimized Central Composite Design process, with purification by an alternative extraction method. Determinations of molecular weight, cytotoxicity, viscosity; proton nuclear magnetic resonance (H-NMR) and Fourier transform infrared-attenuated total reflection (FTIR-ATR) analyses were provided. RESULTS The HA yield obtained was up to c. 12 g L-1 under the reaction conditions of pH 7.8, 33 degrees C incubation temperature, 24 h incubation time and 187 rpm agitation rate. According to gel permeation chromatography results, HA has an average molecular weight of 79 416 Da. FTIR-ATR analysis showed that the spectrum of the standard HA sample overlapped with the spectrum obtained from this study. CONCLUSION In this study, higher titer production of HA was obtained with a simple and economical sequential process. Additionally, the results indicate that the HA produced is an appropriate biomaterial for medical applications. (c) 2019 Society of Chemical Industry
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    Sorafenib and Lithium Chloride Combination Treatment Shows Promising Synergistic Effects in Human Glioblastoma Multiforme Cells in Vitro but Midkine Is not Implicated
    (2014) Sabanci, Pulat Akin; Erguven, Mine; Yazihan, Nuray; Aktas, Esin; Aras, Yavuz; Civelek, Erdinc; Aydoseli, Aydin; Imer, Murat; Gurtekin, Mehmet; Bilir, Ayhan; https://orcid.org/0000-0002-3988-4064; 24512012; ABI-6105-2020
    Objectives: The objectives of this study were to test the effects of the new combination treatment modality, sorafenib (SOR) and lithium chloride (LiCl) and to assess whether midkine (MK) protein has a role in any potential effects. Methods: Monolayer and spheroid cultures of T98G human glioblastoma multiforme (GBM) cells were treated with LiCl and SOR (inhibition concentration 50 value = 100 mu M), or their combination, or were left untreated (control). Cell proliferation and apoptotic indices, the mechanism of action, and the levels of apoptotic and anti-apoptotic proteins were evaluated in monolayer cultures and ultrastructure was evaluated by transmission electron microscopy (TEM) in spheroid cultures after for 72 hours. Results: All drug applications decreased cell numbers and increased the apoptotic index. The combination shows a synergistic effect. In the combination group, the decrease in cell numbers and the increase in the apoptotic index were significantly greater than with the individual drugs (P < 0.01). The combination treatment led to the greatest decreases in MRP-1 and p170 levels; but the greatest decreases in p-STAT-3, p-ERK (P < 0.05), p-AKT, p-GSK-3-beta (P < 0.01), EGFR (P < 0.01), NF-kappa-beta levels were with SOR alone, followed by the combination. The decreases in MK levels in the SOR and combination groups were similar (P = 0.06). Severe ultrastructural damage was more frequently observed in the combination group compared with the other groups. Conclusions: These results suggest the possibility that the addition of LiCl to SOR could improve the prognosis in at least some patients who need both cancer and psychotherapy and indicate the need for further studies.