Browsing by Author "Aktas S."

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    Treatment and prophylaxis with sucralfate ameliorates hypoxia/ reoxygenation-induced intestinal injury in pup rats
    (2005) Sencan A.B.; Sencan A.; Aktas S.; Habif S.; Kabaroglu C.; Parildar Z.; Karaca I.
    Background: Sucralfate is widely used as a cytoprotective agent in patients with peptic ulcer and other intestinal mucosal injury. The aim of this study is to investigate whether sucralfate has any effect on the prevention and treatment of hypoxia/reoxygenation-induced intestinal injury. Material/Methods: Four groups of 10 1-day-old rat pups were studied. Hypoxia/reoxygenation (H/O)-induced intestinal injury was created. Group 1 was subjected to H/O just after birth and sacrificed at the end of the third day (Treatment Control). Group 2 was subjected to H/O just after birth and treated with sucralfate for 3 days. They were sacrificed at the end of the third day (Treatment). Group 3 was subjected to H/O on the third day after birth and then sacrificed (Prophylaxis Control). Group 4 was treated with sucralfate for the first 3 days, then H/O was created. Just after H/O, the pups were sacrificed (Prophylaxis). The intestinal tissues were harvested for histopathological investigation. Malondialdehyde (MDA) levels in the intestinal tissues were determined. Results: The mucosal injury grades of the treatment and prophylaxis groups were significantly lower than those of control groups (p<0.05). The mean MDA level in the treatment and prophylaxis groups were 0.42±0.17 and 0.21±0.23 nmol/mg respectively. The MDA levels of both groups were significantly lower than in the control groups (p<0.05). Conclusions: The present study shows that sucralfate has beneficial effects in an experimental model of hypoxia/reoxygenation-induced intestinal injury. © Med Sci Monit, 2005.
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    Effect of apoptosis and response of extracellular matrix proteins after chemotherapy application on human breast cancer cell spheroids
    (Spandidos Publications, 2006) Oktem G.; Vatansever S.; Ayla S.; Uysal A.; Aktas S.; Karabulut B.; Bilir A.
    Multicellular Tumor Spheroid (MTS) represents a three-dimentional structural form of tumors in laboratory conditions, and it has the characteristics of avascular micrometastases or intervascular spaces of big tumors. Recent studies indicate that extracellular matrix (ECM) proteins play a critical role in tumor metastasis, therefore normal and cancer cells require an ECM for survival, proliferation and differentiation. Doxorubicin and Docetaxel are widely used in the therapy of breast cancer, as well as in in vivo and in vitro studies. In this study, we examined the effect of apoptosis and proliferation of cells on the human breast cancer cell line, MCF-7, by using p53, bcl-2 and Ki67 gene expression, and the tendency to metastasis with extracellular matrix proteins, laminin and type IV collagen after chemotherapy in the spheroid model. The apoptotic cell death in situ was detected by TUNEL method. TUNEL-positive cells and positive immunoreactivities of laminin, type IV collagen, p53 and, bcl-2 were detected in the control group. There was no laminin and type IV collagen immunoreactivities in spheroids of drug groups. While TUNEL-positive cells and p53 immunoreactivity were detected in Docetaxel, Doxorubicin and Docetaxel/Doxorubicin groups, p53 immunoreactivity was not observed in the Docetaxel group. There was no bcl-2 immunoreactivity in either drug group. In addition, we did not detect Ki67 immunoreactivity in both control and drug treatment groups. However, the absence of Ki67 protein in MCF-7 breast multicellular tumor spheroids is possibly related to the cells in G0 or S phase. These chemotherapeutic agents may affect the presence of ECM proteins in this in vitro model of micrometastasis of spheroids. These findings suggest that the possible mechanism of cell death in Doxorubicin and Docetaxel/Doxorubicin treatment groups is related to apoptosis through the p53 pathway. However, we considered the possiblity that there is another control mechanism for the Docetaxel group.
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    Efficiency of bioflavonoids in the prevention of experimental myringosclerosis
    (2010) Ilknur A.E.; Dundar R.; Basoglu S.; Inan S.; Aktas S.; Aslan H.; Ozkul Y.; Ozturkcan S.; Katilmis H.
    Objectives/Hypothesis: It has been noted that some materials with anti-inflammatory and antioxidant effects decrease sclerotic lesions in experimental myringosclerosis. Our purpose in this study is to investigate the effect of micronized purified flavonoid fraction (MPFF), an antioxidant with anti-inflammatory effects, in experimental myringosclerosis in guinea pigs. Materials and Methods: Two study groups were formed. The first group was administered 100mg/kg/day MPFF by catheter for five days before myringotomy and 10 days after myringotomy, while the second group was administered distilled water by the same method, before and after myringotomy. On the 15th day of the study, after the tympanic membranes were examined otomicroscopically for myringosclerosis, they were removed by dissection together with the bone annulus, for histochemical and immunohistochemical examinations. Results: In the MPFF group, the otomicroscopical sclerosis score, inflammation score and tympanic membrane thickness were significantly less than those in the untreated group (p<0.05). It was also determined that the immunoactivity of the anti-VEGF, anti-TGF-beta, anti-eNOS, anti-iNOS, and anti-IL1-beta primary antibodies, which are known to have an important role in angiogenesis and inflammation, significantly decreased in the MPFF group (p<0.05). Conclusion: In conclusion, this study shows that orally administered MPFF can be efficient in the prevention of experimental myringosclerosis in guinea pigs. Copyright 2005 © The Mediterranean Society of Otology and Audiology.
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    Design and Performance Analysis of Coupled Dual Axial Flux PM Machines for Left Ventricular Assist Devices
    (Institute of Electrical and Electronics Engineers Inc., 2025) Karabulut Y.; Mese E.; Ayaz M.; Aktas S.
    This study aims to design a small-sized embedded axial flux permanent magnet synchronous motor (AFPMSM) for a left ventricular assist device (LVAD) pump. The power density per unit volume of the AFPMSM structure is much higher than conventional radial flux permanent magnet machines, so it is preferred for the geometry of the pump structure. For further enhancement in torque density and reliability, dual motors have been fitted into the pump structure successfully. AFPMSM is first analyzed analytically to shrink the design space, and then finite element analysis (FEA) methods were employed to give the motor its final shape. Experimental validations were performed by measuring the back-emf, torque, efficiency, and loss values of the prototyped AFPMSMs. The measured torque constant of 9.58 mNm/Arms ensures that the phase current of 0.35 Arms is sufficient for the LVAD pump when both motors are running at the same time. Compared to other commercial and noncommercial LVAD models, the proposed twin motor structure is superior in terms of volume and weight. Furthermore, it has advantages in terms of patient and device safety due to its natural fault-tolerant structure. Finally, due to the hidden embedded motors, blood flow can be created quite smoothly without any significant impeding effect caused by the motors. This resulted in increased pump efficiency and the desired motor power and torque. In this way, smaller yet more powerful motors can be used. © 1972-2012 IEEE.