Person: ÜYÜKLÜ, MEHMET
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Publication Kanın akışkanlığındaki değişimler birçok hastalığın habercisi olabilir(2015-08-01) ÜYÜKLÜ, MEHMET; ÜYÜKLÜ, MEHMETPublication Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation(2015-12-01) Sircan-Kucuksayan, A.; Uyuklu, MEHMET; CANPOLAT, MURAT; ÜYÜKLÜ, MEHMETTissue oxygen saturation (StO(2)) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO(2). In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO(2) prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO(2) of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO(2)levels of human tissue. The technique developed to measure StO(2) has potential to detect ischemia in real time.Publication Effect of lanthanides on red blood cell deformability and response to mechanical stress: Role of lanthanide ionic radius(2011-01-01T00:00:00Z) Alexy, Tamas; Baskurt, Oguz K.; NEMETH, Norbert; Uyuklu, MEHMET; Wenby, Rosalinda B.; Meiselman, Herbert J.; ÜYÜKLÜ, MEHMETPrior studies exploring the effects of lanthanides (Ln) on red blood cells (RBC) have primarily focused on ion transport, cell fusion, and membrane protein structure. Our previous report [Biorheology 44 (2007), 361-373] dealt only with lanthanum (La) and cell rigidity; the present study extends these observations to other lanthanides (Nd, Sm, Eu, Dy, Er) and to RBC response to mechanical shear. Deformation-shear stress behavior of normal human RBC was measured at Ln concentrations up to 200 mu M. In another series of experiments, RBC were exposed to mechanical stress (190 Pa, 300 s) at 50 mu M Ln and deformation-stress data obtained prior to and after this stress. Data were fitted to a Lineweaver-Burke model to obtain the shear stress at one-half maximum deformation (SS1/2). Our results include: (1) lanthanides cause decreased cell deformability with the magnitude of the decrease dependent on concentration and shear stress; (2) this decrease of deformability is affected by Ln ionic radius such that La > Nd > Sm > Eu > Dy > Er and is reversible for cells in Ln-free media; (3) mechanical stress decreases deformability (i.e., increases SS1/2) such that compared to control, La and Sm reduce and Dy and Er enhance the mechanical stress effect; (4) the decrease of deformability consequent to mechanical stress scales inversely with Ln ionic radius. These results indicate a reciprocal relation between cell rigidity and sensitivity to mechanical stress that is mediated by Ln ionic radius. Additional studies are clearly warranted, particularly those that explore membrane-glycocalyx and intracellular mechanisms.Publication Role of Angiotensin TYpe I and II receptor Blockade in Ischemia/Reperfusion Injury of Isolated Rat Heart(2017-05-04) Kılıç, AYSU; ÜSTÜNOVA, SAVAŞ; Usta, Cansu; BULUT, HURİ; ÜYÜKLÜ, MEHMET; Demirci-Tansel, Cihan; MERAL, İSMAİL; Artumak, Elif; Gurevin-Gürel, Ebru; KILIÇ, AYSU; ÜSTÜNOVA, SAVAŞ; BULUT, HURI; ÜYÜKLÜ, MEHMET; MERAL, İSMAİLPublication Effect of magnesium supplementation on blood rheology in NOS inhibition-induced hypertension model(2016-01-01) CENGİZ, MELİKE; Ulker, Pinar; Uyuklu, MEHMET; YARAŞ, NAZMİ; ÖZEN, NUR; Aslan, Mutay; Özyurt, Dilek; BASRALI, FİLİZ; ÜYÜKLÜ, MEHMETThis study investigated the effects of magnesium on blood rheological properties and blood pressure in nitric oxide synthase (NOS) inhibition-induced hypertension model. Hypertension was induced by oral administration of the nonselective NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME, 25 mg/kg/day) for 6 weeks and systolic blood pressure was measured by the tail-cuff method. The groups receiving magnesium supplementation were fed with rat chow containing 0.8% magnesium oxide during the experiment. At the end of experiment, blood samples were obtained from abdominal aorta, using ether anesthesia. Plasma and erythrocyte magnesium levels were determined by the atomic absorption spectrometer. RBC deformability and aggregation were determined by rotational ektacytometry. Plasma fibrinogen concentration was evaluated by ELISA. Whole blood and plasma viscosities were determined by viscometer and intracellular free Ca++ level was measured by using spectroflurometric method. Blood pressure was elevated in hypertensive groups and suppressed by magnesium therapy. Plasma viscosity and RBC aggregation were found to be higher in hypertensive rats than control animals and these parameters significantly decreased in magnesium supplemented hypertensive animals. Other measurements were not different between experimental groups. These results confirm that blood pressure, plasma viscosity and RBC aggregation increased in NOS inhibition-induced hypertension model and oral magnesium supplementation improved these parameters.Publication Effect of magnesium supplementation on erythrocyte aggregation in NOS inhibition-induced hypertension model(2016-06-08) CENGIZ, MELIKE; ÜYÜKLÜ, MEHMET; ULKER, PINAR; ASLAN, MUTAY; YARAS, NAZMI; OZEN, NUR; GUNDUZ, FILIZ; ÜYÜKLÜ, MEHMETPublication Measurement of Impedance Values of Different Erythrocyte Suspensions(2019-07-01T00:00:00Z) ÜYÜKLÜ, Mehmet; ÜYÜKLÜ, MEHMETObjective: The study was aimed to determine whether the impedance measurements of erythrocyte suspensions can be used with a different calculation method in determining the degree of erythrocyte aggregation. Methods: Impedance measurements of different erythrocyte suspensions were recorded in horizontal glass capillaries with a haematocrit value of 40% with inductance-capacitance-resistance meter after a stop flow generated by the injector pump. Results: As a result of calculating the impedance values of the samples for which the aggregation in phosphate-buffered saline didn't occur, the impedance values of the samples that aggregation at different grades took place were calculated as in the previous measurements of erythrocyte suspensions time course was significantly decreased for in diluted plasmas and was increased for in the 1% dextran 500 solution. It is obvious that aggregation index (Al) was calculated, using Z data exhibited a similar trend for the diluted plasma and plasma with 1% dextran 500, with a rank order of Dextran 500 >whole blood >1/2 diluted plasma. Conclusion: Although impedance measurements of erythrocyte suspensions don't allow for the calculation of erythrocyte aggregation kinetics, it is thought that they can be used as AI which indicates the degree of erythrocyte aggregation.Publication Tam kan saklama koşullarının eritrosit agregasyonuna etkisi(2015-06-01) Ülker, G; Fettahoğlu, E; Çağlayan, O; Aydınoğlu, FK; Dağdelen, HÜLYA; ÜSTÜNOVA, SAVAŞ; ÜYÜKLÜ, MEHMET; DAĞDELEN, HÜLYA; ÜSTÜNOVA, SAVAŞ; ÜYÜKLÜ, MEHMETPublication Investigation of dose-dependent effects of berberine against renal ischemia/reperfusion injury in experimental diabetic rats(2019-01-01) Kanbay, Songül; KUMAŞ, MELTEM; EŞREFOĞLU, MUKADDES; Karataş, Ersin; Duymaç, Nurcihan; ERGÜN, İLYAS SAMET; ÜYÜKLÜ, MEHMET; KOÇYİĞİT, ABDÜRRAHİM; KUMAŞ, MELTEM; EŞREFOĞLU, MUKADDES; ERGÜN, İLYAS SAMET; ÜYÜKLÜ, MEHMET; KOÇYİĞİT, ABDÜRRAHİMBackground: Ischemia-reperfusion injury causes various severe morphological and functional changes in diabetic patients. To date, numerous antidiabetic and antioxidant agents have been used for treatment of the disease-related changes. Objectives: We aimed to examine effective therapeutic doses or doses of berberine against renal ischemia/reperfusion injury (IRI) in a streptozotocin (STZ)-induced diabetic rat model by histopathological and biochemical analysis. Methods: Thirty male Sprague Dawley rats were treated with STZ injection for the development of diabetes, and divided into the following groups: STZ-induced diabetic group (STZ); IRI-induced diabetic group (STZ+IRI); 50mg/kg berberine (BRB) treated diabetic group after inducing IRI (STZ+IRI+BRB1); 100mg/kg BRB treated diabetic group after IRI (STZ+IRI+BRB2); 150mg/kg BRB treated diabetic group after IRI (STZ+IRI+BRB3). Bilateral renal ischemia model was applied for 45min, then reperfusion was allowed for 14 days in STZ-induced diabetic rats. Renal injury was detected histopathologically. Blood urea nitrogen (BUN), creatinine and lactate dehydrogenase (LDH) levels were measured in serum using the ELISA method. Total antioxidant status (TAS) and total oxidant status (TOS) of renal tissue was studied by spectrophotometric assay. Oxidative stress index (OSI) was calculated as TOS-to-TAS ratio. Tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), Na+/K+-ATPase (sodium pump), and Ca2+-ATPase (calcium ATPase) enzyme levels were measured in tissues using the ELISA method. Anti-apoptotic Bax and pro-apoptotic Bcl-2 protein levels were detected by Western blot analysis. All data were evaluated statistically. Results: The highest histopathological score was detected in the STZ+IRI group compared to the other group. BRB administration at the doses of 100mg/kg and 150mg/kg markedly improved renal injury. BUN and creatinine levels significantly increased in the STZ+IRI group compared to the STZ group (p<0.001). 100mg/kg and 150mg/kg BRB administration significantly decreased those levels (p<0.01). The highest TOS and the lowest TAS levels were detected in the STZ+IRI group (p<0.001). IRI markedly aggravated inflammation via increasing levels of TNF-α and CRP (<0.001), and caused apoptosis via inducing Bcl-2 protein, and suppressing Bax protein (p<0.001). BRB administration at the doses of 100mg/kg and 150mg/kg showed anti-oxidant, anti-inflammatory and anti-apoptotic effects (p<0.01). The LDH enzyme, was used as a necrosis marker, was higher in the STZ+IRI group than other groups. BRB administration at all of the doses, resulted in the decline of LDH enzyme level (p<0.001). Ca2+-ATPase and Na+/K+-ATPase enzyme activities decreased in the STZ+IRI group compared to the STZ group (p<0.001), while BRB administration at the doses of 100mg/kg and 150mg/kg significantly increased those of enzyme activities, respectively (p<0.05). Conclusion: Ischemia with diabetes caused severe histopathological and biochemical damage in renal tissue. The high doses of berberine markedly improved histopathological findings, regulated kidney function via decreasing BUN and creatinine levels, and rearranged intercellular ion concentration via increasing Na+/K+-ATPase and Ca2+- ATPase levels. Berberine showed anti-oxidant, anti-apoptotic, and anti-inflammatory effects. According to these data, we suggest that berberine at the doses of 100 and 150mg may be used as a potential therapeutic agent to prevent renal ischemic injury.Publication Eritrosit agregasyon kinetiğine hipoksinin etkisi(2015-06-01) Dağdelen, HÜLYA; Ülker, G; Fettahoğlu, E; Çağlayan, O; Aydınoğlu, FK; ÜSTÜNOVA, SAVAŞ; ÜYÜKLÜ, MEHMET; DAĞDELEN, HÜLYA; ÜSTÜNOVA, SAVAŞ; ÜYÜKLÜ, MEHMET
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