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Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2
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Publication Metadata only A novel microfluidics-based point of care technique for viscoelastic hemostatic assay(IOS Press, 2021) Erten, Ahmet Can; Yalçın, Özlem; Torun, Berfin Irmak; Öz, Fatma; Faculty Member; Master Student; Master Student; School of Medicine; Graduate School of Sciences and Engineering; raduate School of Sciences and Engineering; 218440; N/A; N/AN/APublication Metadata only A structured mechanical risk sensitivity assessment system using red cell deformability and fragmentation parameters(Ios Press, 2021) Yalçın, Özlem; Uğurel, Elif; Göktaş, Polat; Göksel, Evrim; Çilek, Neslihan; Atar, Dila; Faculty Member; Researcher; Researcher; PhD Student; PhD Student; Undergraduate Student; School of Medicine; School of Medicine; School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; School of Medicine; 218440; N/A; N/A; N/A; N/A; N/AN/APublication Metadata only Activation of protein kinase a cascade increases deformability of sickle red blood cells(Ios Press, 2021) Connes, Philippe; Boisson, Camille; Renoux, Celine; Gauthier, Alexandra; Fort, Romain; Nader, Elie; Poutrel, Solene; Göksel, Evrim; Yalçın, Özlem; PhD Student; Faculty Member; School of Medicine; School of Medicine; N/A; 218440Publication Metadata only Applications of deep learning to the assessment of red blood cell deformability(IOS Press, 2021) Turgut, Alper; N/A; Yalçın, Özlem; Faculty Member; School of Medicine; 218440BACKGROUND: Measurement of abnormal Red Blood Cell (RBC) deformability is a main indicator of Sickle Cell Anemia (SCA) and requires standardized quantification methods. Ektacytometry is commonly used to estimate the fraction of Sickled Cells (SCs) by measuring the deformability of RBCs from laser diffraction patterns under varying shear stress. In addition to estimations from model comparisons, use of maximum Elongation Index differences (Delta EImax) at different laser intensity levels was recently proposed for the estimation of SC fractions. OBJECTIVE: Implement a convolutional neural network to accurately estimate rigid-cell fraction and RBC concentration from laser diffraction patterns without using a theoretical model and eliminating the ektacytometer dependency for deformability measurements. METHODS: RBCs were collected from control patients. Rigid-cell fraction experiments were performed using varying concentrations of glutaraldehyde. Serial dilutions were used for varying the concentration of RBC. A convolutional neural network was constructed using Python and TensorFlow. RESULTS and CONCLUSIONS: Measurements and model predictions show that a linear relationship between Delta EImax and rigid-cell fraction exists only for rigid-cell fractions less than 0.2. The proposed neural network architecture can be used successfully for both RBC concentration and rigid-cell fraction estimations without a need for a theoretical model.Publication Metadata only 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/APublication Metadata only Complete remission of Burkitt Lymphoma after surgical excision: a case report(Springer, 2016) Bekoz, Hüseyin Saffet; Kantarcıoğlu, Bülent; Tecimer, Tülay; Uskent, Necdet; Sargın, Deniz; N/A; N/A; Çetiner, Mustafa; Ferhanoğlu, Ahmet Burhan; Faculty Member; Faculty Member; School of Medicine; School of Medicine; N/A; 18320Burkitt lymphoma (BL) is a highly aggressive B cell non-Hodgkin lymphoma that has a high proliferation rate. The prognosis for BL is generally favorable, with cure rate of 75-90 % with modern chemoimmunotherapy regimens. Prompt administration of multiagent immunochemotherapy regimens is critical, because BL is almost always fatal if left untreated. Nevertheless here we report a case of BL that is still in complete remission after more than 4 years without any further treatment after surgical excision of the involved lymph node.Publication Metadata only Cyclin-D1 positive B cell lymphoma with intravascular and interstitial involvement of kidney and bone marrow(Springer, 2023) Altinkaynak, Mustafa; Goksoy, Yagmur; Yegen, Gulcin; Erten, Sebile Nilgun; Saka, Bulent; Akpinar, Timur Selcuk; N/A; Gönenli, Mehmet Gökhan; Teaching Faculty; School of Medicine; Koç University Hospital; 350445Kidney involvement is rare in non-Hodgkin's lymphomas (NHL), and can be caused by direct lymphoid infiltration, paraneoplastic glomerulonephritis (GN), or both. Herein, we present a case of acute kidney injury (AKI) due to renal cyclin-D1 positive B cell lymphoma infiltration. To our knowledge, this is the first case where a renal biopsy revealed intravascular neoplastic cells along with parenchymal infiltration.Publication Metadata only 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/APrior 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 Metadata only Effect of solution and post-mortem time on mechanical and histological properties of liver during cold preservation(IOS Press, 2014) N/A; N/A; Department of Mechanical Engineering; Ayyıldız, Mehmet; Aktaş, Ranan Gülhan; Başdoğan, Çağatay; PhD Student; Faculty Member; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineeringg; School of Medicine; College of Engineering; N/A; 137519; 125489Background: In liver transplantation, the donor and recipient are in different locations most of the time, and longer preservation periods are inevitable. Hence, the choice of the preservation solution and the duration of the preservation period are critical for the success of the transplant surgery. Objective: In this study, we examine the mechanical and histological properties of the bovine liver tissue stored in Lactated Ringer's (control), HTK and UW solutions as a function of preservation period. Methods: The mechanical experiments are conducted with a shear rheometer on cylindrical tissue samples extracted from 3 bovine livers and the change in viscoelastic material properties of the bovine liver is characterized using the fractional derivative Kelvin-Voigt Model. Also, the histological examinations are performed on the same liver samples under a light microscope. Results: The results show that the preservation solution and period have a significant effect on the mechanical and histological properties of the liver tissue. The storage and loss shear moduli, the number of the apoptotic cells, the collagen accumulation, and the sinusoidal dilatation increase, and the glycogen deposition decreases as the preservation period is longer. Conclusions: Based on the statistical analyses, we observe that the liver tissue is preserved well in all three solutions for up to 11 h. After then, UW solution provides a better preservation up to 29 h. However, for preservation periods longer than 29 h, HTK is a more effective preservation solution based on the least amount of change in mechanical properties. on the other hand, the highest correlation between the mechanical and histological properties is observed for the liver samples preserved in UW solution.Publication Metadata only EPO or PlacEPO? Science versus practical experience(IOS Press, 2014) Hardeman, Max; Alexy, Tamas; Brouwer, Bram; Connes, Philippe; Jung, Friedrich; Kuipers, Harm; N/A; Başkurt, Oğuz Kerim; Faculty Member; School of Medicine; N/ARecombinant human erythropoietin (rHuEPO) is an agent commonly used by athletes with the aim to improve performance in endurance sports. However, the scientific community continues to debate the risks, benefits and its mechanism of action when used as a doping agent. This paper provides a brief overview on the pros and cons of rHuEPO use, as discussed by a group of scientist with diverse background, at the 17th Conference of the European Society for Clinical Hemorheology and Microcirculation in Pecs, Hungary. Among multiple topics, panel members challenged the common belief that the increased circulating hemoglobin concentration is the simple key to the improved sporting performance. Rather, hemorheologists developed the concept of optimal hematocrit (Hct), a Hct value that represents the optimal balance between the oxygen transport capacity of blood and blood viscosity. While guideline-directed transfusion therapy is advantageous under pathological conditions, such as severe anemia related to chronic kidney disease, its beneficial effects on endurance in healthy athletes remains questionable. Further studies are warranted in the field evaluating the effects of rHuEPO that are independent of increasing hemoglobin concentration, such as peripheral vasodilation and tissue metabolic changes.