Biomedical subjects

Gareth McKinley

Publications and source records attributed to Gareth McKinley.

3 recordsLinked to original sources

PubMed2002

Electrophoresis using ultra-high voltages.

Optimization of electrophoretic techniques is becoming an increasingly important area of research as microdevices are now routinely adapted for numerous biology and engineering applications. The present work seeks to optimize electrophoresis within microdevices by utilizing ultra-high voltages to increase sample concentration prior to separation. By imaging fluorescently-tagged DNA samples, the effects of both conventional and atypical voltage protocols on DNA migration and separation are readily observed. Experiments illustrate that short periods of high voltage during electrophoretic injection do not destroy the quality of DNA separations, and in fact can enhance sample concentration five-fold. This study presents data that illustrate increases in average resolution, and resolution of longer fragments, obtained from electrophoretic injections utilizing voltages between 85 and 850 V/cm.

DNA↗

PubMed2002

Electrophoretic injection within microdevices.

The flexibility of the microfabricated format creates unique opportunities for study of the electrophoretic process. The present work utilizes digital images to capture the motion of DNA samples during pre-electrophoretic processes. A systematic study of DNA loading and strong sample stacking (sample concentration effects) was performed in order to analyze realistic DNA analysis conditions within microdevices. Using digital imaging and microscopy, DNA sample profiles within the injector were analyzed by deconvolving the geometrical intensity profile into different velocity groups. This analysis illustrates the evolution of molecular separation into distinct migrating populations within the injector itself. The present study performed DNA injections within microfabricated devices imposing run voltages between 85 and 850 V/cm. Data from 3 different offset lengths of a double-T cross-injector, 10 different applied voltages, and 2 different sample preparation protocols are presented.

DNA↗

PubMed2002

Rheology of joint fluid in total knee arthroplasty patients.

While the properties of joint fluid may affect the tribology of joint replacement prostheses, the flow parameters of joint fluid have not yet been examined in the context of total knee arthroplasty (TKA). The objective of this study was to evaluate the flow properties of joint fluids in patients undergoing index TKA or revision TKA. We hypothesized that an alteration of the properties of joint fluid would result from TKA. The steady-shear viscosity and storage and loss moduli were evaluated in joint fluid from 35 arthritis patients undergoing TKA, 14 patients undergoing revision of a previous TKA, and two patients presenting with joint effusion after TKA. The same properties were also evaluated in two commercially available sodium hyaluronate preparations and bovine serum, which is used as a lubricant in joint simulators. The steady-shear viscosity varied over three orders of magnitude among samples obtained from patients undergoing TKA, spanning previously established "normal" and "diseased" ranges. Fluid obtained at index TKA was more likely to exhibit normal viscous properties than fluid obtained at revision TKA (p = 0.01). Other viscous parameters distinguished the two groups, but the difference did not reach statistical significance. Both groups exhibited degenerate flow properties when compared to synovial fluid from healthy individuals. Further examination of the connection between flow properties and the tribology of joint replacement prostheses is warranted.

Adult↗