Michael G. Roper

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A glass microdevice has been constructed for the on-line integration of solid-phase extraction (SPE) of DNA and polymerase chain reaction (PCR) on a single chip. The chromatography required for SPE in the microfluidic sample preparation device (muSPD) was carried out in a silica bead/sol-gel SPE bed, where the purified DNA was eluted directly into a(More)
We describe a microfluidic genetic analysis system that represents a previously undescribed integrated microfluidic device capable of accepting whole blood as a crude biological sample with the endpoint generation of a genetic profile. Upon loading the sample, the glass microfluidic genetic analysis system device carries out on-chip DNA purification and(More)
A microfluidic device has been developed for the determination of insulin secreted from islets of Langerhans by a capillary electrophoresis competitive immunoassay. Online assays were performed by electrophoretically sampling anti-insulin antibody (Ab), fluorescein isothiocyanate-labeled insulin (FITC-insulin), and insulin from separate reservoirs and(More)
L-783,281, an antidiabetic fungal metabolite that has previously been shown to activate insulin signaling in CHO cells, was tested for its effect on intracellular Ca(2+) ([Ca(2+)](i)) and insulin secretion in single mouse pancreatic beta-cells. Application of 10 micromol/l L-783,281 for 40 s to isolated beta-cells in the presence of 3 mmol/l glucose(More)
There are numerous detection methods available for microfluidic analyses. Both conventional and novel detection methods are being put to use for detection on these miniaturized systems, with the analyte of interest driving the choice of detection method. In this article, we summarize microfluidic-based detection strategies from the last 2 years. More focus(More)
Paramagnetic particles in a magnetic ratchet potential were transported in discrete steps in an aqueous solution on the surface of a magnetic garnet film. The proposed technique allows the simultaneously controlled, dispersion-free movement of an ensemble of paramagnetic particles across the surface. External magnetic modulations were used to transport the(More)
The signaling pathway by which insulin stimulates insulin secretion and increases in intracellular free Ca(2+) concentration ([Ca(2+)](i)) in isolated mouse pancreatic beta-cells and clonal beta-cells was investigated. Application of insulin to single beta-cells resulted in increases in [Ca(2+)](i) that were of lower magnitude, slower onset, and longer(More)
Mice with deletion of insulin receptor substrate (IRS)-1 (IRS-1 knockout [KO] mice) show mild insulin resistance and defective glucose-stimulated insulin secretion and reduced insulin synthesis. To further define the role of IRS-1 in islet function, we examined the insulin secretory defect in the knockouts using freshly isolated islets and primary(More)
A microfluidic system was developed to investigate the entrainment of insulin secretion from islets of Langerhans to oscillatory glucose levels. A gravity-driven perfusion system was integrated with a microfluidic system to deliver sinusoidal glucose waveforms to the islet chamber. Automated manipulation of the height of the perfusion syringes allowed(More)