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Biomedical subjects

M S Munro

Publications and source records attributed to M S Munro.

5 recordsLinked to original sources
PubMed1987

Albumin adsorption and retention on C18-alkyl-derivatized polyurethane vascular grafts.

The short-term albumin affinity and thrombo-resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire-reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short-term (4-h) exposure at femoral arterial sites in the dog. 125I-Albumin was preabsorbed on tubes and then exposed to blood for successive 2-h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity-enhancing property of C18 alkylation in the short term. Blood-preconditioning experiments suggested endogenous albumin has a high affinity for the C18-alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18-alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces.

Adsorption↗
PubMed1987

Influence of endogenous albumin binding on blood-material interactions.

A method has been developed to enhance the albumin affinity of a number of medical polymers, based on alkylation of the surface with straight-chain 16- or 18-carbon alkyl groups. This method has been demonstrated to induce the rapid binding of albumin from single and binary protein solutions, from plasma, and apparently, from whole blood. The bound albumin resists fluid shear or chemically induced desorption. Fibrinogen adsorption is inhibited in vitro and in vivo. Complement protein C3 activation from plasma is inhibited. Fibrin formation and platelet aggregation is inhibited in short-term in vivo experiments. Long-term catheter implant studies suggest that the C18 alkylation is more effective than most, if not all, currently available treatments for the retention of a clean, biocompatible, blood-contacting surface. No data have been obtained to date that conflict with the hypothesis that a renewable albumin layer, so formed, blocks the adsorption or conformational alteration of plasma proteins that otherwise might initiate or participate in various host defenses.

Animals↗
PubMed1983

Alkyl derivatized cellulose acetate membranes with enhanced albumin affinity.

Alkylation techniques have been developed for C16 derivatization of cellulose acetate membranes. High yields of alkylated cellulose acetate were obtained which led to correspondingly high yields in albumin adsorption. Centrifugation improved impurity removal and enhanced albumin binding to the membrane. The affinity of the alkylated membranes for albumin diminished with increasing degrees of alkylation, which we attribute to steric hindrance effects. The results suggest that improved thromboresistance may be obtained by such means for hemodialysis, plasmapheresis and other filtration applications.

Adsorption↗
PubMed1982

Indwelling chemical sensors based on semiconductor technology.

Indwelling chemical sensors have been designed and built which operate on similar principles to field effect transistors, the fundamental structural unit of the computer. By appropriate use of ion-filtering membranes with these devices, it is possible to measure, continuously, serum electrolytes, including hydrogen ion, and CO2 tension. Semiconductor processing techniques allow incorporation of multiple ion sensors on a single miniaturized chip. Chip-based signal processing can also allow compensation for temperature effects and other sources of instability. Because these devices can be produced inexpensively, they seem to be promising for patient monitoring in the critical care environment. Problems with stability, blood compatibility, and reference electrode design are addressed and potential solution methods are proposed. The performance of preliminary devices in vitro and in vivo is discussed.

Blood Chemical Analysis↗