Biomedical subjects

S F Elliott

Publications and source records attributed to S F Elliott.

4 recordsLinked to original sources

PubMed2001

Activation of procollagenases is a key control point in cartilage collagen degradation: interaction of serine and metalloproteinase pathways.

OBJECTIVE: Bovine and human cartilages in explant culture respond to proinflammatory cytokines with the up-regulation of procollagenases. In stimulated bovine nasal cartilage (BNC), >90% of collagen is released by day 14 of culture, but collagen release is rarely seen before day 7. The aim of this study was to investigate if activation of procollagenases is a rate-limiting step in cartilage collagen breakdown. METHODS: BNC and human articular cartilage explants were cultured with interleukin-1alpha (IL-1alpha) and/or oncostatin M (OSM) with or without test reagents. Collagen levels were determined by assay of hydroxyproline. Collagenase activity was measured using the diffuse fibril assay. RESULTS: The addition of procollagenase activators, matrix metalloproteinase 3 (MMP-3), and APMA to IL-1alpha/OSM-stimulated BNC resulted in early release of collagen. The release with APMA was completely blocked by the addition of tissue inhibitor of metalloproteinases 1. This shows that procollagenases are present early in the culture period, but cartilage collagen breakdown does not happen until activation occurs. The addition of plasminogen to IL-1alpha/OSM-stimulated cartilage produced early collagen release in bovine and a significant increase in human cartilage. Thus, plasminogen activators (PAs) are present and convert plasminogen to plasmin, a known activator of several MMPs, including collagenases. Addition of alpha1-proteinase inhibitor or a urokinase-type PA inhibitor, 7-amino-4-chloro-3-(3-isothiureidopropoxy) isocoumarin, partially blocked the breakdown of collagen from IL-1alpha/OSM-treated bovine cartilage. This suggests that serine proteinases are involved in the activation cascades of procollagenases that result in cartilage collagen breakdown. CONCLUSION: The activation of procollagenases is a key control point in cartilage collagen breakdown, and serine proteinase pathways activate MMPs.

Animals↗

PubMed1994

A simple method for isolating alpha 2 macroglobulin-cytokine complexes.

There is the need for a simple, effective procedure for separating alpha 2 macroglobulin-cytokine complexes from free cytokine in order that the nature and possible immunological significance of cytokine-binding by alpha 2 macroglobulin (alpha 2-M) might be further investigated. This presentation describes a method which exploits the presence of zinc-binding sites on alpha 2-M which permit the isolation of complexes from other proteins by zinc-affinity chromatography. Furthermore the method may be used in either a column or batch format.

Chromatography, Affinity↗

PubMed1994

The effect of alpha 2 macroglobulin in commercial cytokine assays.

alpha 2 macroglobulin (alpha 2M), a 725 kDa plasma protein, has been reported to bind a range of cytokines. We have therefore investigated its effect on a number of commercial cytokine assays. The methylamine converted fast form of the molecule was found to reproducibly depress, by 26% or more, the standard curves obtained with certain commercial assays for IL-2 and for tumor necrosis factor alpha, and had a small inhibitory effect on some IL-4 assays. In contrast it slightly enhanced or had no effect on ELISAs for IL-1 beta and IL-6. The inhibition observed was directly proportional to the concentration of alpha 2 M used in the range 0.5-5 mg/ml. Studies in the IL-2 system also revealed that it was largely attributable to the fast form of alpha 2M. Preliminary evidence suggests that the effects observed may be dependent on the assay source. These findings may be relevant to the assay of biological fluids in which alpha 2 M is present.

Artifacts↗

PubMed1981

Response of hamster trachea in organ culture to Mount St. Helens volcano ash.

The effects of Mount St. Helens volcanic ash on rings of hamster tracheal epithelium in organ culture were studied. Volcanic ash samples with mass median aerodynamic diameters (MMAD) of 7.7 micrometers and 1.6 micrometers caused markedly different alterations in the tracheal mucosa. Examination by SEM of the ventral epithelial surface of tissue from untreated control explants after 2 weeks in culture showed equal numbers of ciliated and microvillous cells. Examination by SEM of tracheas exposed to the smaller size particles revealed that ash concentrations as low as 1 microgram/ml increased mucous secretion after one 2-hr exposure. After four or nine 2-hr exposures, cells contained cilia that were short and blunt. Ciliary activity after these exposures showed a significant depression in beating frequency. Tracheal ring cultures exposed to the larger volcanic ash particles exhibited moderate cytomorphological changes after one 2-hr exposure at concentrations of 1, 10 and 100 micrograms/ml. As the number of exposures increased, most of the columnar cell layer was lost, resulting in exposure of the basal cells. After nine exposures at the two highest concentrations of ash (10 and 100 micrograms/ml), only a few ciliated cells were remaining. Statistically significant reductions in ciliary activity paralleled the epithelial damage. The degree of epithelial damage and changes in the cilia beating frequency were related to the dose and the number of exposures to the volcanic ash.

Animals↗