Researcher:
Başkurt, Oğuz Kerim

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Oğuz Kerim

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Başkurt

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Başkurt, Oğuz Kerim

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2010 - 201630

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Now showing 1 - 10 of 30
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    A comparison of capillary and venous blood sampling methods for the use in haemorheology studies
    (Ios Press, 2011) Simmonds, Michael J.; Meiselman, Herbert J.; Marshall-Gradisnik, Sonya M.; N/A; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    There is accumulating evidence that exercise may improve disturbed haemorheological parameters that are typically observed in various chronic diseases, thus there is a growing interest in exploring the influence of various exercise models for the improvement of haemorheology. Blood sampling using venipuncture, however, can be limiting during exercise and/or in field settings. The purpose of the present study was to investigate whether venous and capillary blood samples yield comparable red blood cell (RBC) deformability and aggregation indices. Twelve healthy volunteers (6 males and 6 females; age 30 +/- 9 yrs; body mass index 24.9 +/- 2.8 kgm(-2)) provided blood samples that were collected simultaneously from: i) a prominent forearm vein by venipuncture; ii) the earlobe using a lancet; iii) the middle finger using a lancet. Haematocrit, RBC deformability (Rheoscan-D, Sewon Meditech Inc., Korea) and RBC aggregation (Myrenne GmbH, Roetgen, Germany) were measured for each sample. Haematocrit and RBC deformability were not different between the three sampling sites, and the group averages of RBC aggregation parameters were not different between the three sampling methods. The time course of RBC aggregation was slower when using blood sampled from the earlobe, and there was stronger agreement between RBC aggregation parameters measured using venous and capillary finger samples compared with venous and earlobe. It is suggested that capillary blood sampling from the finger may provide a reliable alternative to venous blood sampling in clinical and field settings.
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    Haemorheology of the eastern grey kangaroo and the Tasmanian devil
    (Csiro Publishing, 2011) Simmonds, Michael; Marshall- Gradisnik, Sonya; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
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    Measurement of red blood cell aggregation in disposable capillary tubes
    (IOS Press, 2011) Uyuklu, Mehmet; Özdem, Sebahat; Meiselman, Herbert J.; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    A new method is described in this paper that allows measurement of red blood cell (RBC) aggregation indexes in disposable glass tubes within minutes. Light transmission through the RBC suspension filled into a microhematocrit capillary at stasis is recorded during RBC aggregation; a novel method assures an initial dispersion of aggregates in the capillary. The resulting light transmittance-time data are analyzed to calculate various parameters. Measurement of erythrocyte sedimentation rate (ESR) and RBC aggregation using well established methods and the newly developed capillary tube aggregometer in blood samples with a wide range of RBC aggregation indicated significant correlations between these parameters. Additionally, light transmittance during complete disaggregation allows estimating hematocrit, thereby enabling hematocrit correction of the measured and calculated parameters. The newly developed capillary tube RBC aggregometer is suitable for use as a method to rapidly monitor disease activity and the acute phase response, especially at the point-of-care (e. g., health care facilities, physician's office) and for field studies.
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    Red blood cell aggregation parameters measured by capillary tube aggregometer using venous and capillary blood samples
    (Korean Soc Rheology, 2011) Simmonds, Michael J.; Christy, Rhys; Marshall-Gradisnik, Sonya M.; Meiselman, Herbert J.; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    The extent of red blood cell (RBC) aggregation has widely been accepted as a reliable indicator of inflammatory processes. The ability to measure RBC aggregation indexes in capillary blood samples may simplify the application of the test and may bring advantages in its clinical usage as well as application in field studies. This study compared RBC aggregation indexes measured in venous and capillary blood samples using a newly developed capillary tube aggregometer. Although strong correlations between aggregation indexes measured in capillary and venous samples were detected, the indexes measured in venous samples were higher compared to capillary samples, thus indicating a bias. The possible reason for this bias is proposed to be related to the difference in oxygen saturation of venous and capillary samples and therefore altered the light absorption spectrums. Our results indicate that capillary blood samples can be used to estimate RBC aggregation in venous blood samples, however the bias should be taken into account.
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    Exercise training enhances flow-mediated dilation in spontaneously hypertensive rats
    (Acad Sciences Czech Republic, Inst Physiology, 2011) Gündüz, Filiz; Koçer, Günnur; Ülker, Seher; Meiselman, Herbert J.; Şentürk, Ümit Kemal; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    This study investigated the effect of exercise training on the flow-mediated dilation (FMD) in gastrocnemius muscle arteries from spontaneously hypertensive rats (SHR). SHR and WKY rats were divided into sedentary and exercised groups. After swimming exercise for eight weeks, the isolated arteries were mounted on pressurized myograph and FMD responses examined. The role of nitric oxide (NO), prostaglandins (PGs) and endothelium derived hyperpolarizing factor (EDHF) on FMD were assessed by obtaining dilation responses in the presence and absence of pharmacological antagonists. N-omega-nitro-L-arginine methyl ester (L-NAME), indomethacin (INDO) and tetraethylamonium (TEA) were used to inhibit nitric oxide synthase, cyclooxygenase and EDHF-mediated responses, respectively. The FMD response was significantly blunted in arteries of SHR compared with WKY rats, and, improved by exercise training in SHR (SHR-ET) group. In SHR arteries, L-NAME and TEA did not affect dilation responses to flow, while INDO led to a significant enhancement in this response. Although dilation response was not altered by L-NAME in arteries obtained from trained SHR, TEA caused a significant attenuation and INDO led to significant increases. These results demonstrate that exercise training improves FMD in SHR, and, this enhancement induced by exercise training occurs through EDHF-mediated mechanism(s).
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    Vascular fluid mechanics in the regulation of endothelial function
    (CRC Press, 2013) Meiselman, Herbert J.; N/A; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    Vascular endothelium is one of the large organs of the human body with a number of cells on the order of 1013; the total weight of endothelial cells in a 70 kg man is several hundred grams. These cells are arranged as the inner surface of all blood vessels, and thus the total surface area of endothelium which is in contact with blood is on the order of several thousand square meters under resting conditions; this area can be increased several fold in response to increased demand for blood flow in certain tissues (e.g., during strenuous exercise) by means of capillary recruitment (Wolinsky 1980).
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    Abnormal blood rheology and chronic low grade inflammation: possible risk factors for accelerated atherosclerosis and coronary artery disease in Lewis negative subjects
    (Elsevier, 2015) Alexy, Tamas; Pais, Eszter; Wenby, Rosalinda B.; Mack, Wendy J.; Hodis, Howard N.; Kono, Naoko; Wang, Jun; Fisher, Timothy C.; Meiselman, Herbert J.; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    Objective: To test the hypothesis that abnormal hemorheology and chronic low-grade inflammation are more prevalent in Lewis negative individuals, possibly contributing to premature atherosclerosis. Methods and results: We enrolled 223 healthy subjects (154 females, mean age: 64yrs). Conventional risk factors, markers of inflammation and hemorheological profiles were measured; Lewis blood group was determined by serology. Conventional risk factors (age, gender, BMI, blood pressure, lipid profile, smoking habit) did not differ among Lewis phenotypes. However, markers of inflammation (WBC, hs-CRP, ESR) were significantly elevated and rheological parameters (RBC aggregation, plasma viscosity) were abnormal in Lewis negative subjects, especially when compared to the Le(a-b+) group. Conclusions: With a prevalence of 33% in select populations, our data support the hypothesis that Le(a-b-) represents a pro-inflammatory phenotype that may contribute to the elevated cardiovascular risk in this group. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
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    Tissue oxygen demand in regulation of the behavior of the cells in the vasculature
    (Wiley, 2013) Barvitenko, Nadezhda N.; Aslam, Muhammad; Filosa, Jessica; Matteucci, Elena; Nikinmaa, Mikko; Pantaleo, Antonella; Saldanha, Carlota; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    The control of arteriolar diameters in microvasculature has been in the focus of studies on mechanisms matching oxygen demand and supply at the tissue level. Functionally, important vascular elements include EC, VSMC, and RBC. Integration of these different cell types into functional units aimed at matching tissue oxygen supply with tissue oxygen demand is only achieved when all these cells can respond to the signals of tissue oxygen demand. Many vasoactive agents that serve as signals of tissue oxygen demand have their receptors on all these types of cells (VSMC, EC, and RBC) implying that there can be a coordinated regulation of their behavior by the tissue oxygen demand. Such functions of RBC as oxygen carrying by Hb, rheology, and release of vasoactive agents are considered. Several common extra-and intracellular signaling pathways that link tissue oxygen demand with control of VSMC contractility, EC permeability, and RBC functioning are discussed.
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    Assessment of oxidant susceptibility of red blood cells in various species based on cell deformability
    (IOS Press, 2011) Simmonds, Michael J.; Meiselman, Herbert J.; Marshall-Gradisnik, Sonya M.; Pyne, Michael; Kakanis, Michael; Keane, James; Brenu, Ekua; Christy, Rhys; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
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    Effect of lanthanides on red blood cell deformability and response to mechanical stress: role of lanthanide ionic radius
    (Ios Press, 2011) Alexy, Tamas; Nemeth, Norbert; Uyuklu, Mehmet; Wenby, Rosalinda B.; Meiselman, Herbert J.; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/A
    Prior 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.