Evaluation of a Compact, Portable Centrifuge for Separating Microvolume Blood Samples at the Point of Collection.

Background: The increased demand for decentralized blood sample collection presents numerous operational challenges for diagnostics providers. Sample degradation including sample hemolysis due to time, temperature, and handling between collection and laboratory analysis leads to limited test menus and unreliable results. Here we introduce the lightweight, portable Labcorp TrueSpin™ for rapid point-of-care blood separation using commercially available microvolume blood collection tubes.

Clinical Evaluation of the Torq Zero Delay Centrifuge System for Decentralized Blood Collection and Stabilization.

Blood sample collection and rapid separation-critical preanalytical steps in clinical chemistry-can be challenging in decentralized collection settings. To address this gap, the Torq™ zero delay centrifuge system includes a lightweight, hand-portable centrifuge (ZDrive™) and a disc-shaped blood collection device (ZDisc™) enabling immediate sample centrifugation at the point of collection. Here, we report results from clinical validation studies comparing performance of the Torq System with a conventional plasma separation tube (PST).

At-home sperm testing for epidemiologic studies: Evaluation of the Trak male fertility testing system in an internet-based preconception cohort.

Background: Semen quality assessment in population-based epidemiologic studies presents logistical and financial challenges due to reliance on centralised laboratory semen analysis. The Trak Male Fertility Testing System is an FDA-cleared and validated at-home test for sperm concentration and semen volume, with a research use only sperm motility test. Here we evaluate the Trak System's overall utility among men participating in Pregnancy Study Online (PRESTO), a web-based study of North American couples planning pregnancy.

Novel centrifugal technology for measuring sperm concentration in the home.

Objective: To evaluate the analytical performance and usability of the Trak Male Fertility Testing System, a semiquantitative (categorical) device recently US Food and Drug Administration (FDA)-cleared for measuring sperm concentration in the home by untrained users.

Design: A three-site clinical trial comparing self-reported lay user results versus reference results obtained by computer-aided semen analysis (CASA).

Setting: Simulated home use environments at fertility centers and urologist offices.

Centrifugal microfluidic platform for ultrasensitive detection of botulinum toxin.

We present an innovative centrifugal microfluidic immunoassay platform (SpinDx) to address the urgent biodefense and public health need for ultrasensitive point-of-care/incident detection of botulinum toxin. The simple, sample-to-answer centrifugal microfluidic immunoassay approach is based on binding of toxins to antibody-laden capture particles followed by sedimentation of the particles through a density-media in a microfluidic disk and quantification by laser-induced fluorescence. A blind, head-to-head comparison study of SpinDx versus the gold-standard mouse bioassay demonstrates 100-fold improvement in sensitivity (limit of detection = 0.

A centrifugal fluidic immunoassay for ocular diagnostics with an enzymatically hydrolyzed fluorogenic substrate.

We present a novel "Lab-on-a-Disk" platform and demonstrate its capability for rapid and sensitive measurement of vascular endothelial growth factor (VEGF) intended for patients suffering from diabetic retinopathy (DR) and age-related macular degeneration (AMD). This approach combines sedimentation principles applied to microspheres under centrifugal force with signal amplification using an enzyme and a fluorogenic substrate for readout. The simple single channel per assay platform separates, washes and concentrates antibody-coated microspheres from excess label to produce a sensitive fluorogenic response proportional to the amount of VEGF in the sample.

Whole blood immunoassay based on centrifugal bead sedimentation.

Background: Centrifugal "lab on a disk" microfluidics is a promising avenue for developing portable, low-cost, automated immunoassays. However, the necessity of incorporating multiple wash steps results in complicated designs that increase the time and sample/reagent volumes needed to run assays and raises the probability of errors. We present proof of principle for a disk-based microfluidic immunoassay technique that processes blood samples without conventional wash steps.

Orai1 regulates intracellular calcium, arrest, and shape polarization during neutrophil recruitment in shear flow.

Orai1 was reported to function as a calcium channel subunit that facilitates store operated calcium entry (SOCE) in T cells and is necessary for formation of the immune synapse. We reasoned that SOCE via Orai1 might regulate PMNs activation during recruitment to inflamed endothelium. Orai1 function was assessed by real-time imaging of calcium transients as PMNs were stimulated to roll, arrest, and migrate on E-selectin and ICAM-1 in shear flow.

Transmigration of neutrophils across inflamed endothelium is signaled through LFA-1 and Src family kinase.

Leukocyte capture on inflamed endothelium is facilitated by a shift in LFA-1 from low to high affinity that supports binding to ICAM-1. LFA-1 bonds help anchor polymorphonuclear leukocytes (PMN) to inflamed endothelium in shear flow, and their redistribution to the leading edge guides pseudopod formation, migration, and extravasation. These events can be disrupted at the plasma membrane by stabilizing LFA-1 in a low- or intermediate-affinity state with allosteric small molecules.

Leucocyte recruitment under fluid shear: mechanical and molecular regulation within the inflammatory synapse.

1. Nature has evolved an exquisite system for regulation of leucocyte recruitment at sites of tissue inflammation. Mechanical energy translated to the red and white blood cells transports them from large arteries down to the microcirculation.

Spatial regulation of inflammation by human aortic endothelial cells in a linear gradient of shear stress.

Objective: Atherosclerosis is a focal disease that develops at sites of low and oscillatory shear stress in arteries. This study aimed to understand how endothelial cells sense a gradient of fluid shear stress and transduce signals that regulate membrane expression of cell adhesion molecules and monocyte recruitment.

Methods: Human aortic endothelial cells were stimulated with TNF-alpha and simultaneously exposed to a linear gradient of shear stress that increased from 0 to 16 dyne/cm2.

Optical and fluorescence detection of neutrophil integrin activation.

Neutrophils are among the first cells to respond to acute inflammation through a multistep process initiated by selectin mediated rolling, which transitions to an integrin/intercellular adhesion molecule-dependent arrest and transmigration across endothelium. A conformational shift in the CD11/CD18 adhesion receptor on neutrophils is a critical determinant of the efficiency of recruitment on inflamed endothelium. For instance, beta2-integrin expression level is upregulated up to 10-fold by fusion of cytoplasmic granule pools of CD11b/CD18 (Mac-1).

Calcium flux in neutrophils synchronizes beta2 integrin adhesive and signaling events that guide inflammatory recruitment.

Intracellular calcium flux is an early step in the signaling cascade that bridges ligation of selectin and chemokine receptors to activation of adhesive and motile functions during recruitment on inflamed endothelium. Calcium flux was imaged in real time and provided a means of correlating signaling events in neutrophils rolling on E-selectin and stimulated by chemokine in a microfluidic chamber. Integrin dependent neutrophil arrest was triggered by E-selectin tethering and ligation of IL-8 seconds before a rapid rise in intracellular calcium, which was followed by the onset of pseudopod formation.

SLIC-1/sorting nexin 20: a novel sorting nexin that directs subcellular distribution of PSGL-1.

P-Selectin glycoprotein ligand-1 (PSGL-1) is a mucin-like glycoprotein expressed on the surface of leukocytes that serves as the major ligand for the selectin family of adhesion molecules and functions in leukocyte tethering and rolling on activated endothelium and platelets. Previous studies have implicated the highly conserved cytoplasmic domain of PSGL-1 in regulating outside-in signaling of integrin activation. However, molecules that physically and functionally interact with this domain are not completely defined.

Neutrophil adhesion to E-selectin under shear promotes the redistribution and co-clustering of ADAM17 and its proteolytic substrate L-selectin.

E-selectin is expressed by the vascular endothelium and binds flowing neutrophils in the blood to facilitate their recruitment into the underlying tissue at sites of inflammation. L-selectin on neutrophils is engaged by E-selectin and undergoes rapid clustering and then coalescence in the trailing edge of polarizing cells. These processes are believed to increase the valency and capacity of L-selectin to signal CD18 integrin activity.

Vascular mimetics based on microfluidics for imaging the leukocyte--endothelial inflammatory response.

We describe the development, validation, and application of a novel PDMS-based microfluidic device for imaging leukocyte interaction with a biological substrate at defined shear force employing a parallel plate geometry that optimizes experimental throughput while decreasing reagent consumption. The device is vacuum bonded above a standard 6-well tissue culture plate that accommodates a monolayer of endothelial cells, thereby providing a channel to directly observe the kinetics of leukocyte adhesion under defined shear flow. Computational fluid dynamics (CFD) was applied to model the shear stress and the trajectory of leukocytes within the flow channels at a micron length scale.

Triglyceride-rich lipoproteins prime aortic endothelium for an enhanced inflammatory response to tumor necrosis factor-alpha.

High levels of triglyceride-rich lipoproteins (TGRLs) in blood are linked to development of atherosclerosis, yet the mechanisms by which these particles initiate inflammation of endothelium are unknown. TGRL isolated from human plasma during the postprandial state was examined for its capacity to bind to cultured human aortic endothelial cells (HAECs) and alter the acute inflammatory response to tumor necrosis factor-alpha. HAECs were repetitively incubated with dietary levels of freshly isolated TGRL for 2 hours per day for 1 to 3 days to mimic postprandial lipidemia.

Impaired integrin-dependent function in Wiskott-Aldrich syndrome protein-deficient murine and human neutrophils.

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency that manifests as increased susceptibility to many pathogens. Although the spectrum of infections suffered by WAS patients is consistent with defects in neutrophil (PMN) function, the consequences of WAS protein (WASp) deficiency on this innate immune cell have been unclear. We report that deficiency of WASp in both human and murine PMNs resulted in profound defects in clustering of beta2 integrins, leading to defective adhesion and transendothelial migration under conditions of physiologic shear flow.

Dynamic shifts in LFA-1 affinity regulate neutrophil rolling, arrest, and transmigration on inflamed endothelium.

Polymorphonuclear leukocyte (PMN) recruitment to vascular endothelium during acute inflammation involves cooperation between selectins, G-proteins, and beta2-integrins. LFA-1 (CD11a/CD18) affinity correlates with specific adhesion functions because a shift from low to intermediate affinity supports rolling on ICAM-1, whereas high affinity is associated with shear-resistant leukocyte arrest. We imaged PMN adhesion on cytokine-inflamed endothelium in a parallel-plate flow chamber to define the dynamics of beta2-integrin function during recruitment and transmigration.

Cytoskeletal interactions regulate inducible L-selectin clustering.

L-selectin (CD62L) amplifies neutrophil capture within the microvasculature at sites of inflammation. Activation by G protein-coupled stimuli or through ligation of L-selectin promotes clustering of L-selectin and serves to increase its adhesiveness, signaling, and colocalization with beta(2)-integrins. Currently, little is known about the molecular process regulating the lateral mobility of L-selectin.