Browsing by Author "Yang, Xiaoxi"
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Item A rapid paper-based test for quantifying sickle hemoglobin in blood samples from patients with sickle cell disease(American Journal of Hematology, 6/1/2016) Piety, Nathaniel Z.; Yang, Xiaoxi; Lezzar, Dalia; George, Alex; Shevkoplyas, Sergey S.Quantification of sickle hemoglobin (HbS) in patients with sickle cell disease (SCD) undergoing hydroxyurea or chronic transfusion therapy is essential to monitoring the effectiveness of these therapies. The clinical monitoring of %HbS using conventional laboratory methods is limited by high per-test costs and long turnaround times usually associated with these methods. Here we demonstrate a simple, rapid, inexpensive paper-based assay capable of quantifying %HbS in blood samples from patients with SCD. A 20 ?L droplet of whole blood and hemoglobin solubility buffer was deposited on chromatography paper. The relative color intensities of regions of the resulting blood stain, determined by automated image analysis, are used to estimate %HbS. We compared the paper-based assay with hemoglobin electrophoresis (comparison method) using blood samples from 88 subjects. The test shows high correlation (R2 = 0.86) and strong agreement (standard deviation of difference = 7 %HbS) with conventional Hb electrophoresis measurement of %HbS, and closely approximates clinically predicted change in %HbS with transfusion therapy (mean difference 2.6 %HbS, n = 4). The paper-based assay can be completed in less than 35 minutes and has a per-test cost less than $0.25. The assay is accurate across a wide range of HbS levels (10–97%) and hemoglobin concentrations (5.6–12.9 g/dL) and is unaffected by high levels of HbF (up to 80.6%). This study demonstrates the feasibility of the paper-based %HbS assay. The paper-based test could improve clinical care for SCD, particularly in resource-limited settings, by enabling more rapid and less expensive %HbS monitoring.Item Deterioration of red blood cell mechanical properties is reduced in anaerobic storage(Blood Transfusion, 1/14/2016) Burns, Jennie M.; Yoshida, Tatsuro; Dumont, Larry J.; Yang, Xiaoxi; Piety, Nathaniel Z.; Shevkoplyas, Sergey S.Background Hypothermic storage of red blood cells (RBCs) results in progressive deterioration of the rheological properties of the cells, which may reduce the efficacy of RBC transfusions. Recent studies have suggested that storing RBC units under anaerobic conditions may reduce this storage-induced deterioration. Materials and methods The aim of this study was to compare the rheological properties of conventionally and anaerobically stored RBC and provide a measure of the relationship between oxidative damage to stored RBC and their ability to perfuse microvascular networks. Three different microfluidic devices were used to measure the ability of both types of stored RBC to perfuse artificial microvascular networks. Flow rates of the RBC passing through the entire network (bulk perfusion) and the individual capillaries (capillary perfusion) of the devices were measured on days 2, 21, 42, and 63 of storage. Results The bulk perfusion rates for anaerobically stored RBC were significantly higher than for conventionally stored RBCs over the entire duration of storage for all devices (up to 10% on day 42; up to 14% on day 63). Capillary perfusion rates suggested that anaerobically stored RBC units contained significantly fewer non-deformable RBC capable of transiently plugging microfluidic device capillaries. The number of plugging events caused by these non-deformable RBC increased over the 63 days of hypothermic storage by nearly 16- to 21-fold for conventionally stored units, and by only about 3- to 6-fold for anaerobically stored units. Discussion The perfusion measurements suggest that anaerobically stored RBC retain a greater ability to perfuse networks of artificial capillaries compared to conventionally (aerobically) stored RBC. It is likely that anaerobic storage confers this positive effect on the bulk mechanical properties of stored RBC by significantly reducing the number of non-deformable cells present in the overall population of relatively well-preserved RBC.Item Quantifying morphological heterogeneity: a study of more than 1 000 000 individual stored red blood cells(Vox Sanguinis, 10/1/2016) Piety, Nathaniel Z.; Gifford, Sean C.; Yang, Xiaoxi; Shevkoplyas, Sergey S.Background and Objectives The morphology of red blood cells (RBCs) deteriorates progressively during hypothermic storage. The degree of deterioration varies between individual cells, resulting in a highly heterogeneous population of cells contained within each RBC unit. Current techniques capable of categorizing the morphology of individual stored RBCs are manual, laborious, error-prone procedures that limit the number of cells that can be studied. Our objective was to create a simple, automated system for high-throughput RBC morphology classification. Materials and Methods A simple microfluidic device, designed to enable rapid, consistent acquisition of images of optimally oriented RBCs, was fabricated using soft lithography. A custom image analysis algorithm was developed to categorize the morphology of each individual RBC in the acquired images. The system was used to determine morphology of individual RBCs in several RBC units stored hypothermically for 6–8 weeks. Results The system was used to automatically determine the distribution of cell diameter within each morphological class for >1,000,000 individual stored RBCs (speed: >10,000 cells/hour; accuracy: 91.9% low-resolution, 75.3% high-resolution). Diameter mean and standard deviation by morphology class: discocyte 7.80±0.49?m, echinocyte 1 7.61±0.63?m, echinocyte 2 7.02±0.61?m, echinocyte 3 6.47±0.42?m, sphero-echinocyte 6.01±0.26?m, spherocyte 6.02±0.27?m, stomatocyte 1 6.95±0.61?m, stomatocyte 2 7.32 ± 0.47?m. Conclusion The automated morphology classification procedure described in this study is significantly simpler, faster and less subjective than conventional manual procedures. The ability to evaluate the morphology of individual RBCs automatically, rapidly and in statistically significant numbers enabled us to perform the most extensive study of stored RBC morphology to date.Item Validation of a Low-Cost Paper-Based Screening Test for Sickle Cell Anemia(PLoS One, 1/6/2016) Piety, Nathaniel Z.; Yang, Xiaoxi; Kanter, Julie; Vignes, Seth M.; George, Alex; Shevkoplyas, Sergey S.The high childhood mortality and life-long complications associated with sickle cell anemia (SCA) in developing countries could be significantly reduced with effective prophylaxis and education if SCA is diagnosed early in life. However, conventional laboratory methods used for diagnosing SCA remain prohibitively expensive and impractical in this setting. This study describes the clinical validation of a low-cost paper-based test for SCA that can accurately identify sickle trait carriers (HbAS) and individuals with SCA (HbSS) among adults and children over 1 year of age.