Kevin Nakamura

Early Biomarkers of Stroke

BACKGROUND The diagnosis and management of acute ischemic stroke are limited by the lack of rapid diagnostic assays for use in an emergency setting. Computed tomography (CT) scanning is used to diagnose hemorrhagic stroke but is relatively ineffective (<33% sensitive) in detecting ischemic stroke. The ability to correlate blood-borne protein biomarkers with stroke phenotypes would aid in the development of such rapid tests. METHODS ELISAs for >50 protein biomarkers were developed for use on a high-throughput robotic workstation. These assays were used to screen plasma samples from 214 healthy donors and 223 patients diagnosed with stroke, including 82 patients diagnosed with acute ischemic stroke. Marker assay values were first compared by univariate analysis, and then the top markers were subjected to multivariate analysis to derive a marker panel algorithm for the prediction of stroke. RESULTS The top markers from this analysis were S-100b (a marker of astrocytic activation), B-type neurotrophic growth factor, von Willebrand factor, matrix metalloproteinase-9, and monocyte chemotactic protein-1. In a panel algorithm in which three or more marker values above their respective cutoffs were scored as positive, these five markers provided a sensitivity of 92% at 93% specificity for ischemic stroke samples taken within 6 h from symptom onset. CONCLUSION A marker panel approach to the diagnosis of stroke may provide a useful adjunct to CT scanning in the emergency setting.

Microarray Immunoassays in the Microfluidic Triage® Protein Chip

The Triage® protein chip is a tool for the simultaneous measurement of up to 100 different proteins by immunoassay. The immunoassays are performed in a microfluidic plastic chip and results are achieved in 15 minutes with picomolar sensitivities directly from several drops of whole blood or plasma. Microfluidic fluid flow is controlled passively in the protein chip by the surface architecture and surface hydrophobicity in the microcapillaries. The immunoassays utilize high affinity antibodies and a near infrared fluorescent label, which is read by a portable, battery powered fluorometer. The products aid emergency room physicians in the rapid diagnosis of myocardial infarction, congestive heart failure, and drug overdose.