Biomedical subjects

P Predecki

Publications and source records attributed to P Predecki.

8 recordsLinked to original sources

PubMed1980

Prevention of platelet adhesion to porous surfaces.

Porous samples of cellulose diacetate/nitrate CAN (millipore filter), polycarbonate PC (nuclepore filter), cellulose diacetate Ca, and polydimethyl siloxane SR of various pore sizes were immersed in stirred heparinized human blood while being perfused with lactated Ringer's solution at various rates. Control samples were exposed to the blood in the absence of perfusion. The control tests showed that CAN and PC adhered platelets rapidly to plateau levels of 1--5 X 10(6)/cm2 in approximately 4 min, while CA and SR remained platelet-free. The critical perfusion rate vp* to prevent adhesion of platelets (and all formed elements) to the CAN and PC was approximately 0.1 cc/min cm2 at a shear rate of approximately 620 sec-1 independent of pore size tested. vp* increased slightly with stirring rate. A simplified diffusion-convection model was used to qualitatively account for the effects observed.

Adsorption↗

PubMed1980

Measurement of the activation time for platelet adhesion to foreign surfaces.

An apparatus is described which permitted a perfusant (lactated Ringer's solution) to be passed through a porous sample in a pulsatile manner with a square wave pressure profile. The "on" time, "off" time, number of cycles and pressure amplitude were separately controllable. Using this apparatus and immersing the sample in stirred, heparinized, human blood, there was a certain "off" time below which platelet adhesion to the sample abruptly ceased. The values of this "off" time, termed the activation time ta for platelet adhesion were approximately 0.5 sec for 0.2 micrometers pore size cellulose diacetate/nitrate (millipore filter) and approximately 0.3 sec for 0.2 micrometers polycarbonated (nuclepore filter). After a single cycle with a 5 sec "off" time, adhered platelets on both these materials showed pseudopodia, varying degrees of spreading and membrane perforation.

Adsorption↗

PubMed1977

Blood-compatible materials by fluid perfusion.

The feasibility of preventing platelet adhesion to porous foreign surfaces in contact with blood by passing (perfusing) a physiologic fluid through the pores into the blood was tested. Porous-walled tubes of Teflon (Gore-tex) and aluminosilicate ceramic were perfused with lactated Ringer's solution at rates between 3.13 and 0.3 cc/min per cm2 of perfused surfaced and exposed to heparinized and unheparinized flowing human whole blood for periods of 3-6 min. Under these conditions, with 0.159 cm I.D. tubes and a mean blood flow rate of 8.3 cm/sec, the adhesion of all blood cells was prevented, compared with the adhesion of 1 to 8 X 10(6) platelets/cm2 on the nonperfused controls. The adhesion of plasma proteins was also markedly reduced as determined by bromophenol blue staining. The critical perfusion rate to prevent platelet adhesion to Gore-tex (0.5 micron pore size, 60% pore volume) was found to be between 0.04 and 0.3 cc/(min-cm2). The boundary layer produced by a perfused segment of porous tubing prevented platelet adhesion for several centimeters downstream from the perfusing segment under experimental conditions used.

Aluminum Silicates↗

PubMed1974