Browsing by Author "Yazar, H."

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Effects of iloprost and n-acetylcysteine on ischemia-reperfusion injury and thiol/disulfide hemostasis in rats
(2023.01.01) Yildiz, Y.A.; Altintoprak, F.; Celebi, F.; Oter, V.; Cakar, G.C.; Yazar, H.; Cakiroglu, H.; Muhtaroglu, A.
Aim: Intestinal ischemia occurs after partial or complete obstruction of the intestinal arterial blood flow, and reperfusion injury following the restoration of blood flow. Intestinal ischemia-reperfusion [IIR] damage can cause multiple organ failure and death. In our study, we aimed to observe the effect of ilioprost and N-acetylcysteine on ischemia-reperfusion injury and to show the effect of the Thiol disulfide mechanism in this area. Material and Methods: Thirty Sprague Dawley rats were divided into five groups of six animals each: sham, IIR, IIR+IL, IIR+NAC and IIR+NAC+IL. Intestinal samples and blood were collected after completion of the sham or IIR protocol. Small-bowel samples were evaluated according to the Chiu score. Thiol/disulfide [DS] hemostasis was followed using a novel series of serum biomarkers. Serum concentrations of total thiol, native thiol and disulfide were also determined. Results: The average Chiu score was lower in the IIR + NAC group than in both the IIR and the IIR + IL group, but the differences were not statistically significant. The score in the sham group was significantly lower than those of the other four groups. The level of reduced thiol and the native thiol/total thiol [NT/TT] ratios were higher in groups treated with NAC, IL or both. In the latter groups, oxidized thiol, DS/TT and DS/NT ratios were lower than in the IIR group but the differences between the three treatment groups were not statistically significant. Discussion: The addition of IL to NAC was not more protective than NAC alone in a rat model of IIR injury. Our results suggest that markers of thiol-DS hemostasis can be used as indicators of antioxidant mechanisms in IIR injury.
Microstructural, mechanical, and biocompatibility properties of Ti-Cu/B4C composites for biomedical applications
(2024.01.01) Islak, S.; Houssain, H.; Emin, N.; Yazar, H.; Danaci, H.C.; Koç, V.
This study investigated the effects of B4C on the microstructural, mechanical, and biocompatibility properties of Ti-Cu/B4C composites produced by powder metallurgy. Different amounts of B4C (3, 6, 9, and 12 %) were added to the Ti-Cu matrix. XRD results showed that Ti2Cu, alpha-Ti, TiB, and B4C phases formed in the microstructure. The addition of B4C and the phases forming in the microstructure resulted in significant increases in the hardness and wear resistance of the composites. SEM images of the wear surfaces showed that the abrasive wear mechanism was dominant. Biodegradability analyses showed that sodium, found in trace amounts in the structure of the alloys, and calcium, released from the structure of B4C into the medium, were the least at the addition of 6 % B4C. Considering the reduced amount of phosphate in the medium, it was found that the mass gain observed in the specimens was due to the deposition of calcium-phosphate precipitates on the surface of the composites. This result suggested that Ti-Cu/B4C alloys were bioactive for bone and may provide osteointegration. Indirect MTT analysis with bone marrow mesenchymal stem cells showed that the specimens were cytotoxic at an acute dose on the first day. However, the cytotoxic effect diminished when they were kept in the PBS medium and replaced every other day for 28 days. Notably, the composite specimen with the addition of 6 % B4C demonstrated maximum cytocompatibility. Consequently, it indicated that adding B4C to the alloy improved osteogenic properties, although it partially increased copper release into the medium.
Microstructural, mechanical, and biocompatibility properties of Ti–Cu/B4C composites for biomedical applications
(Elsevier Ltd, 2024) Islak, S.; Houssain, H.; Emin, N.; Yazar, H.; Danacı, H.C.; Koç, V.
This study investigated the effects of B4C on the microstructural, mechanical, and biocompatibility properties of Ti–Cu/B4C composites produced by powder metallurgy. Different amounts of B4C (3, 6, 9, and 12 %) were added to the Ti–Cu matrix. XRD results showed that Ti2Cu, α-Ti, TiB, and B4C phases formed in the microstructure. The addition of B4C and the phases forming in the microstructure resulted in significant increases in the hardness and wear resistance of the composites. SEM images of the wear surfaces showed that the abrasive wear mechanism was dominant. Biodegradability analyses showed that sodium, found in trace amounts in the structure of the alloys, and calcium, released from the structure of B4C into the medium, were the least at the addition of 6 % B4C. Considering the reduced amount of phosphate in the medium, it was found that the mass gain observed in the specimens was due to the deposition of calcium-phosphate precipitates on the surface of the composites. This result suggested that Ti–Cu/B4C alloys were bioactive for bone and may provide osteointegration. Indirect MTT analysis with bone marrow mesenchymal stem cells showed that the specimens were cytotoxic at an acute dose on the first day. However, the cytotoxic effect diminished when they were kept in the PBS medium and replaced every other day for 28 days. Notably, the composite specimen with the addition of 6 % B4C demonstrated maximum cytocompatibility. Consequently, it indicated that adding B4C to the alloy improved osteogenic properties, although it partially increased copper release into the medium.