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Biomedical subjects

R A Odell

Publications and source records attributed to R A Odell.

7 recordsLinked to original sources
PubMed2000

Acute cellular interaction with textured surfaces in blood contact.

Textured blood-contacting surfaces can promote the formation of a blood-compatible pseudo-neointima. We hypothesized that by controlling the surface texturing, the pseudo-neointima thickness could be controlled. The hypothesis was tested experimentally by fabricating the polyurethane textured surfaces with three different fiber lengths, and exposing them simultaneously to the flowing blood in an ovine ex vivo carotid-jugular series shunt for periods up to 4 h. The textured surface consisted of regularly spaced tapered micro-fibers of defined length on a smooth base-plane surface. Because of the simple surface topography, detailed computational fluid-dynamic modeling of the surface could be obtained as a parallel study. Experimental results showed that white cell was the predominant cell type deposited on the textured surfaces, whereas macroscopic thrombus formation occurred only in one of nine blood-contacting experiments. White cell density on the textured base-plane surface was subsequently quantified by image-analyzing the electron micrographs of blood-contacted textured surfaces. The statistical analysis of cell densities on individual textured surfaces showed effects of wall shear stress on the textured base plane (which was obtained from the fluid-dynamic modeling), the longitudinal position of the test section in the series shunt, and blood-contact time.

Animals↗
PubMed1999

Comparison between the clonogenic, MTT, and SRB assays for determining radiosensitivity in a panel of human bladder cancer cell lines and a ureteral cell line.

Using a series of human bladder cancer cell lines and an immortalised normal ureteral cell line, radiosensitivities measured by three different methods after a single dose of X-radiation are compared. Clear differences between cell survival curves obtained using the clonogenic, microtetrazoline (MTT) and sulforhodamine B (SRB) assays are shown. The most sensitive of the assays investigated was the clonogenic assay. The MTT and SRB assays were found to be relatively insensitive especially at lower radiation levels, suggesting that these assays may not be suitable for predicting therapeutic dose schedules in vivo, but will be important for investigating radio-sensitivity in cell lines with very low plating efficiencies. Each assay discriminated between a range of sensitivities in the cell lines examined, and with some minor differences, the ordering of sensitivities using the three assays was similar. Possible explanations for the differences between results obtained with the three assays are discussed.

Cell Survival↗
PubMed1991

Beta 2-microglobulin kinetics in end-stage renal failure.

The kinetics of beta 2-microglobulin (beta 2m) were studied in five anephric or anuric hemodialysis patients. Human beta 2m was isolated from peritoneal dialysate using ion-exchange and gel chromatography and radiolabeled with 125I. Patients were injected with 10 microCi labeled beta 2m. In one study (N = 4), plasma activity was measured over 72 hours. In a second study (N = 4), patients received low-flux dialysis 24 hours after injection and high-clearance dialysis (Bellco BL655) at 48 hours. Plasma activities were fitted to a three-compartment, variable volume model. Endogenous beta 2m levels (radioimmunoassay) were 56 +/- 6 mg/liter. The beta 2m distribution volume was 12.7 +/- 2.0 liter (0.20 +/- 0.03 liter/kg) and the non-renal clearance was 3.0 +/- 0.4 ml/min. The generation rate, 9.9 +/- 1.7 mg/hr (0.16 +/- 0.04 mg/kg/hr), was similar to that measured in subjects with normal renal function. The three compartment model derived from the turnover data gave an adequate fit of the arterial concentrations of endogenous and exogenous beta 2m during low-flux (nil beta 2m clearance) and high-clearance (beta 2m clearance of 19 ml/min) dialysis. Simulations based on this model indicate that extracorporeal treatment can at best remove about 50% of weekly production. These results suggest that beta 2m production is not increased in dialysis patients, that there is substantial non-renal beta 2m clearance, and that the amount of beta 2m that can be removed by extracorporeal therapy is therefore limited.

Adult↗
PubMed1987

A model of ultrafiltration and glucose mass transfer kinetics in peritoneal dialysis.

We have investigated the variation with dwell time of dialysate volume and glucose concentration during continuous ambulatory peritoneal dialysis using a one-pool model. No assumption was made regarding the ultrafiltration rate that was calculated by the model. Results show that the volume ultrafiltered during dwell time is an increasing function of peritoneal membrane hydraulic permeability and a decreasing function of glucose mass transfer coefficient (MTC). For large MTC and low initial glucose concentration there is reabsorption of dialysate into the blood at large dwell times. For a 6 h dwell time, glycerol (92 daltons) is a more effective osmotic agent than glucose (198 daltons) at the same weight concentration. These results are in quantitative agreement with published clinical studies.

Biological Transport, Active↗
PubMedDate not supplied

Beta 2-microglobulin kinetics in an ovine model.

The kinetics of 125I-beta 2 microglobulin (beta 2M) and 51Cr-EDTA were measured in normal and nephrectomized sheep. In normal sheep the beta 2M clearance was similar to that of EDTA (i.e., glomerular filtration rate), as were the distribution volumes. In anephric sheep the beta 2M clearance was 7.7 +/- 1.4 ml/min.

Animals↗