Biomedical subjects

S A Gibson

Publications and source records attributed to S A Gibson.

23 records · Page 2Linked to original sources

PubMed1988

Identification of extractable proteins from the bovine ocular zonule: major zonular antigens of 32kD and 250kD.

Using Western immunoblotting, the extractable proteins of the bovine zonular fibers were examined for reactivity with two zonular antisera known to have strong affinity for zonular fibers in tissues, in order to identify the antigenic components. The extracts were also tested with antisera to several matrix proteins that have been reported to be associated with zonular fibers. Proteins reactive with antisera to bovine serum albumin, serum immunoglobulins and fibronectin were present. No bands reactive with antisera to a-elastin, prealbumin, amyloid P component, collagen VI, lysyl oxidase or monoclonal antibody to fibrillin were demonstrated. The major nonserum protein band identified by both antisera was a 32kD polypeptide. An equally strong 250kD polypeptide was shown by the antiserum to guanidine-dithiothreitol extracted zonular fibers. Both of these proteins were PAS-positive and were demonstrated also by the antisera in extracts of bovine elastic neck ligament. Whether the two glycoproteins are related to each other, with the higher molecular weight protein either a precursor or aggregate form, is not yet clear. They appear to bear a close relationship to the elusive core microfibrillar protein.

Animals↗

PubMed1986

Extrapolation of biodegradation results to groundwater aquifers: reductive dehalogenation of aromatic compounds.

The reductive biodegradation of a variety of haloaromatic substrates was monitored in samples from two sites within a shallow anoxic aquifer and was compared with freshwater sediment and sewage sludge. The metabolic capacity existing in methane-producing aquifer material was very similar to that in sediment in that three of four chlorobenzoates, five of seven chlorophenols, and one of two chlorophenoxyacetate herbicides were reductively dehalogenated in both types of incubations. The 2,4-dichlorophenoxyacetate was first converted to a dichlorophenol before dehalogenation occurred. Sewage sludge microorganisms dehalogenated four of seven chlorophenols tested and degraded both phenoxyacetate herbicides by first converting them to the corresponding chlorophenols, but the microorganisms did not transform the chlorobenzoates. In general, the same suite of initial metabolites were produced from a test substrate in all types of samples, as confirmed by cochromatography of the intermediates with authentic material. Aquifer microbiota from a sulfate-reducing site was unable to significantly degrade any of the haloaromatic substrates tested. Biological removal of the sulfate in samples from this site permitted dehalogenation of a model substrate, while stimulation of methanogenesis without removal of sulfate did not. These results demonstrate that dehalogenating microorganisms were present at this site but that their activity was at least partially inhibited by the high sulfate levels.

Anaerobiosis↗

PubMed1986

Pseudoexfoliative material contains an elastic microfibrillar-associated glycoprotein.

Because of histochemical similarities, there is reason for thinking that some component or components of PSX material are also present in zonular fibers. Since the zonule is a member of the elastic microfibrillar system, PSX material on the lens capsule was tested for immunologic affinity to elastic MFP from three widely divergent sources, using an indirect immunoperoxidase electron microscopic method. Positive staining was obtained with all three antibodies on all components of lens PSX material, including the superficial aggregates, deep fibrogranular zone, and capsular inclusions. The results support our hypothesis that PSX material derives from abnormal polymerization of glycoprotein associated with the zonular-elastic microfibrillar system. Similar staining of the abnormal material within the lens capsule indicates that the lens epithelial cell is involved in processing this protein. It might be suspected that other microfibrillar-secreting cells, even beyond the present range of suspected sources, could produce similar material.

Antibodies, Monoclonal↗

PubMed1986

Lectin binding to pseudoexfoliative material and the ocular zonules.

Lectin staining of pseudoexfoliative material on the lens capsule, zonules, and iris showed the presence of the beta-D-galactose (1-3) galactosamine sequence, alpha-D-galactosamine, beta-D-galactose, beta-(1-4)-D-glucosamine, and terminal sialic acid. Mono and difucosyl binding sites were also found. The likelihood that the lectins were binding to two different galactosamine-containing moieties was supported by their different distributions in the photoreceptors. These affinities suggest a complex carbohydrate composition in pseudoexfoliative material, with both O-linked sialomucin-type and N-linked oligosaccharide chains.

Anterior Eye Segment↗

PubMed1983

The protein composition of the ocular zonules.

Bovine and human zonules were found to be composed of noncollagenous acidic glycoprotein with a high cysteine content, double that previously reported. In reduced zonular fractions the most prominent peptide had a molecular weight (MW) of approximately 70,000. Lesser quantities of 170,000, 50,000, and 35,000 dalton peptides were also present and a variable number of lower MW bands, depending upon the degree of reduction and denaturation. A fraction of bovine zonules soluble in low ionic strength buffers contained primarily a peptide of approximately 50,000 daltons, often present as a doublet. Amino acid and hexosamine content of these two fractions was consistent with the presence of at least two different glycoconjugates, one a proteoglycan. Carbohydrate analysis of whole zonules suggested that these glycoconjugates include a sialofucose-containing glycoprotein and a lesser quantity of xylose-containing proteoglycan. The amino acid profile and peptide content of the zonules resembled that of elastic tissue microfibrils, increasing further the possibility of a close relationship between these two fibrils.

Adult↗