Biomedical subjects

F Hampson

Publications and source records attributed to F Hampson.

14 recordsLinked to original sources

PubMed2001

An investigation of mucus/polymer rheological synergism using synthesised and characterised poly(acrylic acid)s.

A range of poly(acrylic acid)s with different average degrees of polymerisation and cross-linking densities were synthesised using a solution polymerisation process. The rheological characteristics of aqueous dispersions of these materials and those of mixtures with homogenised pigs gastric mucus were investigated using dynamic oscillatory rheology, and compared to the known mucoadhesive Carbopol 934P. From the storage moduli, the rheological synergy and relative rheological synergy were calculated, and the effects of concentration and pH on this considered. Generally, the larger the molecular weight (and degree of cross-linking), the greater the rheological synergy, with Carbopol 934P giving the most pronounced effect. Rheological synergy was seen to be concentration-dependent, and a maximum concentration to produce an optimum effect was evident. Acid pHs were seen to favour synergy, although in marked contrast to previous literature reports, the optimum mucus-polymer interaction was not observed at the half ionised value (pH = pKa) but at pH regimes that were unique to each polymer type. This could be influenced by the structural constrains imposed on potential hydrogen bonded interactions. It was concluded that synthesising poly(acrylic acid)s with better defined physicochemical properties than commercially available polymers will advance the study of the phenomenon of rheological synergy.

Acrylic Resins↗

PubMed2001

Synthesis of radiolabeled congeners of the carbomers: (14)C-labeled poly(acrylic acid)s.

A general method for the synthesis of (14)C-acrylic acid is described in detail. The material is used for the synthesis of a range of radiolabeled poly(acrylic acid)s in which the (14)C-label forms an integral part of the polymer backbone. The chemical structure of the synthesized polymers is examined in the light of spectroscopic data, molecular weight determinations, and rheological studies.

Acrylates↗

PubMed2001

The gastrointestinal transit profile of 14C-labelled poly(acrylic acids): an in vivo study.

The gastrointestinal distribution profiles for three 14C-labelled poly(acrylic acid)s of different average molecular weights and degrees of cross-linking have been established using the rat model. Despite initial differences in transit times and retention characteristics, these structural features were found to be of little influence to the overall gastrointestinal transit of the materials under consideration. No evidence for the systemic absorption of any of the polymers could be identified.

Acrylic Resins↗

PubMed1989

Immune mediators increase adherence of T-lymphocytes to human lung fibroblasts.

The purpose of the present study was to determine whether immunological mediators that are known to be released in the lungs of patients with active sarcoidosis might increase the adherence of human T-lymphocytes to human lung fibroblasts. The studies demonstrate that interleukin 1 (IL-1), tumor necrosis factor (TNF), gamma-interferon (IFN), and interleukin 2 (IL-2) increase the adherence of T-lymphocytes to fibroblasts in a dose- and time-dependent manner. An effect of IL-1, TNF, and IFN was observed at concentrations less than 1 ng/ml; an effect of IL-2 was not observed unless greater than or equal to 60 ng/ml of the mediator was used. The effect of the mediators was primarily on the fibroblasts; however, a significant increase in adherence was also observed when the T-lymphocytes were preincubated with the mediators. These observations suggest that there may be an intimate relationship between the immune response and the fibrotic response in the lungs of patients with pulmonary sarcoidosis or in other disorders where tissue fibrosis is mediated by immunological processes.

Cell Adhesion↗

PubMed1989

Effects of chlorinated amines on endothelial and epithelial barriers in vitro and ex vivo.

Chlorinated amines are long-lived oxidants released from inflammatory cells. They have been observed to alter the function of important inflammatory molecules. Whether they can contribute directly to the inflammatory alteration of cellular barriers is not known. Monolayers of cultured porcine pulmonary artery endothelial cells, monolayers of cultured dog kidney tubular epithelial cells (MDCK), and the vascular surface of an isolated perfused rabbit lung were exposed to taurine chloramine. Taurine chloramine increased albumin flux across the endothelium, decreased the electrical resistance across the epithelium, and increased the hydraulic conductivity of the rabbit lung vasculature. These alterations in barrier function appeared to occur in the absence of cytolysis of the cells making up the barriers. These results suggest that chlorinated amines, long-lived oxidants released from inflammatory cells, may contribute directly to alteration of cellular barriers.

Albumins↗

PubMed1984

A comparative study of properties and toxic constituents of funnel web spider (Atrax) venoms.

The crude venoms of male and female Sydney funnel web spiders, Atrax robustus, were compared by cation-exchange and high-performance liquid chromatography, lethality to new-born mice, polyacrylamide gel isoelectric focusing, immunoelectrophoresis, phospholipase A analysis, effects on the mouse phrenic nerve hemidiaphragm and passive paw oedema in the rat and, except in the case of rat paw oedema, were found to exhibit quite different properties. Polyacrylamide gel isoelectric focusing and high-performance liquid chromatography proved to be suitable for gender and species determination when applied to the venoms of A. formidabilis, A. infensus, A. robustus and A. versutus. These venoms were also compared by lethality, promotion of muscle fasciculation and phospholipase A activity.

Animals↗

PubMed1979

Displacement electrophoresis in gel as a technique for separating proteins on a preparative scale.

A preparative displacement electrophoresis apparatus has been developed for the fractionation of proteins and other macromolecules. The separation is carried out down a vertical annular gel which is supported by a cylindrical glass cooler. The gel is protected from evaporation by a heavy inert insulating liquid with the terminating electrolyte floating on it. Very high potential drops and instabilities in the terminating electrolyte are avoided by continuously lowering the level of the inert liquid during the course of the separation. Fluorescent mobility markers have been synthesized, which make it possible to follow the progress of the separation and to divide the gel into fractions, once the separation is complete.

Animals↗

PubMed1978