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At least 1,225 records · Page 68Linked to original sources
PubMed1995

The transfer of polystyrene microspheres from the gastrointestinal tract to the circulation after oral administration in the rat.

Factors relating to the transfer of latex microspheres of 0.87 micron mean diameter from the gastrointestinal tract (GIT) to the circulation have been investigated. The rapidity of appearance and the number of particles increased when the volume of water used as a suspending vehicle was increased. This was probably due to barrier cell integrity being compromised so that the movement of particles across the enterocytes would be enhanced. Particles were swept into these channels by the waterflow. The tonicity of the fluid was important as isotonic and hypertonic saline were not as effective as water in transferring particles. Particles were transferred from GIT segments adjacent to the stomach which may in part explain the rapid appearance of particles in the circulation. Particle uptake was blocked by cytochalasin B which suggests an active component may also be involved.

Administration, Oral↗
PubMed2002

Opsonophagocytosis of fluorescent polystyrene beads coupled to Neisseria meningitidis serogroup A, C, Y, or W135 polysaccharide correlates with serum bactericidal activity.

We developed a polysaccharide-specific flow cytometric opsonophagocytic assay (OPA) for the simultaneous measurement of functional antibody to Neisseria meningitidis serogroups A, C, Y, and W135. OPA titers significantly correlated with serum bactericidal assay titers for all serogroups tested (mean r = 0.96; P < 0.001). OPA could be used in meningococcal vaccine evaluation.

Adult↗
PubMed1995

Polystyrene microspheres decrease bronchial artery resistance in anesthetized sheep.

The use of microspheres to measure tissue blood flow requires that the microspheres themselves do not alter regional arterial tone. To determine whether microspheres affected bronchial artery resistance, we cannulated and perfused the bronchial artery in anesthetized sheep. In seven sheep, the change in bronchial artery pressure at constant flow was recorded during infusion of 5 doses (1 x 10(5), 2 x 10(5), 5 x 10(5), 1 x 10(6), and 1.5 x 10(6)) of 15-microns microspheres. Microspheres produced a dose-dependent, self-limited decrease in bronchial artery pressure (1.5 x 10(6) microspheres decreased bronchial artery pressure by 36% for 31 min). This was a decrease in bronchial artery resistance, as evidenced by a shift in the slope, but not the intercept, of a pressure-flow curve (n = 4 sheep). Left atrial injection of 1 x 10(7) microspheres decreased bronchial artery resistance by 17% in six sheep with intact bronchial arteries in which flow was measured by ultrasound probe. The adenosine-receptor antagonist 8-phenyltheophylline attenuated the fall in resistance by 79% (n = 4 sheep). Cyclooxygenase inhibition by indomethacin attenuated the response by 37% (n = 4 sheep). These results suggest that microspheres caused the release of adenosine and a vasodilator prostaglandin. Repetitive measurements of bronchial blood flow by microspheres could overestimate true bronchial blood flow if the interval between measurements is < 30 min.

Animals↗
PubMed1983

In vitro thrombogenicity test of materials used in arterial prostheses. Comparison of fibrin deposition from blood on glass polystyrene and arterial prostheses.

Coagulation rates in fresh, normal, venous blood was investigated when a given volume of blood was allowed to contact various materials of equivalent surface area, at 22 degrees C, without disturbance. The coagulation rate was determined indirectly by measuring residual thrombin-clottable fibrinogen in cell-free supernatants after arresting coagulation at fixed time intervals with a Ca++-chelating type of anticoagulant and comparing the thrombin-clottable fibrinogen content of the test samples with control samples of blood anticoagulated immediately after venipuncture. In glass containers, after initial formation of the clot, progressive fibrin formation, measured by the rate of disappearance of thrombin-clottable fibrinogen, was found to take place as a gradual and linear progressive process not complete at 30 min after venipuncture with blood stored undisturbed at 22 degrees C. Various graft materials in tubular form were prepared to ensure equivalent blood surface contact. These were investigated for their influence on fibrinogen to fibrin conversion of fresh venous blood in a 15-min period at 22 degrees C. Fibrin formation was greatest in microvel pre-treated with clotting blood and decreased in the following order: microvel, woven Dacron, knitted dacron and Gore-tex. Gore-tex showed by far the least thrombogenicity of all the tested graft materials. We discuss our reasons for making our measurements under non-flow conditions and the reason for measuring fibrinogen to fibrin conversion rather than measuring platelet deposition on the various surfaces.

Arteries↗
PubMed1992

Control of adhesion and detachment of parenchymal liver cells using lactose-carrying polystyrene as substratum.

Adhesion of hepatocytes on culture dishes whose surface was coated with a lactose-carrying styrene homopolymer (PVLA) was investigated. Hepatocytes maintained their round shape on PVLA substratum, which is in contrast to the usual spread shape characteristic of those cultured on collagen and fibronectin substrata. Calcium ion was indispensable for hepatocyte adhesion in PVLA substratum, and hence the hepatocytes on PVLA were easily detached when the culture was treated with ethylenediamine tetraacetic acid (EDTA). The recovered hepatocytes readheres to PVLA. The adhesion of hepatocytes to PVLA was not inhibited by cytochalasin B but by colchicine. Hepatocytes recognize the galactose moieties on the surface of asialoglycoproteins and removes these proteins from the blood stream by receptor mediated endocytosis. The mechanism of adhesion of hepatocytes on PVLA substratum which contains a high density of galactose residues was distinct from the attachment on collagen and fibronectin substrata, and showed great similarity to the receptor and ligand interactions which occurs in the clearance of asialoglycoproteins by hepatocytes.

Animals↗
PubMed1993

On the structure of electrical double layer of IgG immobilized on polystyrene microspheres.

Latex particles used in the development of immunoassays usually present stability problems when the antibody is attached to the surface. This work is an attempt to know the potential distribution parameters around these complexes by electrokinetic measurements. The conversion of mobility data into zeta-potential was carried out by different theoretical approaches developed by Smoluchowski (classical equation), O'Brien and White, and Dukhin and Semenikhin. The zeta-potential calculated with allowance for electrical double layer (e.d.l.) polarization was substantially greater than zeta calculated according to the classical electrokinetic theory. The greater values of zeta D-S in comparison with zeta O-W were readily explained on the basis that in the first theory, the contribution to polarization from all ions of the diffuse layer was taken into account, whereas O'Brien and White accounted for only the ions of the hydrodynamically mobile part of the e.d.l. This is an indication that the anomalous surface conductance of latex particles coated by IgG molecules is much higher than that of bare latex particles.

Adsorption↗