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Biomedical subjects

R Ryder

Publications and source records attributed to R Ryder.

At least 37 records · Page 2Linked to original sources
PubMed1985

Structural analysis of hepatitis B surface antigen by monoclonal antibodies.

A method has been developed for the analysis of hepatitis B surface antigen (HBsAg) antigenic structure at the molecular level that creates "fingerprints" or "signatures" of various hepatitis B viral (HBV) strains. This technique employs high affinity IgM and IgG monoclonal antibodies (anti-HBs) directed against distinct and separate determinants on HBsAg. In performing this antigenic structural analysis, separate binding curves for different monoclonal anti-HBs are generated by measuring immunoreactivity in serial dilutions of HBsAg-positive serum by radioimmunoassay. Since the HBsAg concentration in serum is unknown, the binding profiles of groups of samples are aligned by an iterative least-squares procedure to generate the numerical signature characteristic of the viral strain. The numerical signatures are then displayed on a computer-graphic plot. The signature profiles of HBsAg subtypes are a true reflection of their antigenic structure, and in vertical and horizontal transmission studies the molecular characteristics of the viral epitopes are conserved. By signature analysis we found substantial antigenic heterogeneity among the ayw3 strain both in the U.S. and France, as well as in populations of the Far East and Africa. Populations in Ethiopia, Gambia, and the Philippines were infected with two antigenically distinct HBV strains. In some newly identified HBV strains, it was found that epitopes identified by some monoclonal antibodies were absent or substantially reduced, which suggested that a genetic mutation may have occurred. Thus this study suggests that there is far more antigenic heterogeneity in HBV than previously recognized. These variants are antigenically distinct from each other at the epitope level, and were heretofore unrecognized by polyvalent anti-HBsAg antibodies.

Adult↗
PubMed1982

Post-mortem study of emphysema in coalworkers and non-coalworkers.

A post-mortem survey of emphysema in coalworkers and non-coalworkers was carried out in men aged 50-70 years dying of ischaemic heart disease (IHD). It was determined that in such men selection for necropsy was similar in coalworkers and non-coalworkers. All lungs were examined in a standard way and the amounts of centrilobular and panacinar emphysema were scored on numerical scales. Emphysema in men dying of IHD was significantly more frequent in coalworkers than in non-coalworkers even after age and smoking habits were accounted for by stratification. In the coalworkers, the severity of emphysema was related to the amount of dust in simple foci in the lungs. Because both groups were selected similarly from their parent populations the relative frequency of emphysema found in this study reflects that in the whole populations of coalworkers and non-coalworkers in the study area and confirms an excess of emphysema in coalworkers. This excess is likely to be due to occupational factors.

Aged↗
PubMed1979

Heat-labile enterotoxin production in isolates from a shipboard outbreak of human diarrheal illness.

As reported elsewhere, an enterotoxigenic strain of Escherichia coli serotype O25:K98:NM was epidemiologically incriminated as the etiological agent in a shipboard outbreak of diarrheal illness. This enterotoxigenic E. coli strain and possibly other enteric isolates were found to produce heat-labile toxin and not heat-stable toxin. Since previous genetic analyses of enterotoxigenic E. coli strains producing heat-labile and heat-stable toxins have shown a plasmid location for both toxin determinants and since in this outbreak more than one bacterial strain appeared to produce only heat-labile toxin, the possibility of an extrachromosomal heat-labile toxin determinant was investigated. Results of endonuclease cleavage and hybridization experiments, as well as apparent heat-labile toxin phenotypic instability, strongly suggest a plasmid mediation of toxin production. Additionally, the stability of this heat-labile toxin production was evaluated after several traditional methods of bacterial cell preservation.

Bacterial Toxins↗
PubMed1972

Pulmonary disability in coal workers' pneumoconiosis.

Results from a correlation survey which compared radiological and physiological findings during life with detailed morbid anatomical findings in the lungs of 247 deceased miners and ex-miners with pneumoconiosis were used to assess the extent and significance of their pulmonary disability.Coal workers' pneumoconiosis usually caused progressive impairment of ventilation, which in the simple type of disease was not related to radiological category. In such cases the presence of emphysema was found to be a more important factor in determining the impairment of ventilation than the radiological category of simple pneumoconiosis.

Aged↗
PubMed1970

Emphysema in coal workers' pneumoconiosis.

A correlation survey has been carried out between the pathological, physiological, and radiological findings pertaining to emphysema in 247 deceased coal miners and ex-miners, most of whom had been diagnosed as suffering from coal workers' pneumoconiosis during life. The pathological findings, which included large lung sections and detailed histology in every case, were compared with similar findings in a contrast non-mining population matched for age and sex.The results indicated that emphysema was much more common among the coal miners, both with simple and with complicated pneumoconiosis, than among the contrast group. In addition the extent of the emphysema as measured by a recognized "counting" method carried out on paper-mounted lung sections was remarkably closely related to ventilatory impairment as evidenced by the forced expiratory volume in one second.Extensive emphysema was more commonly found in those pneumoconiosis cases, both simple and complicated, showing the finer punctiform type of radiological change than in cases showing the larger micronodular and nodular opacities.

Adult↗