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Biomedical subjects

J A Spence

Publications and source records attributed to J A Spence.

12 recordsLinked to original sources
PubMed1992

The effect of periodontal disease on sulphated glycosylaminoglycan distribution in the sheep periodontium.

The glycosylaminoglycan (GAG) distribution in the soft periodontal tissues of the sheep was investigated topographically in healthy tissue and the changes associated with periodontal disease determined and correlated with increasing disease severity. Total sulphated GAG content was determined spectrophotometrically and the proportions of individual GAGS measured after separation by cellulose acetate electrophoresis. In healthy tissue, total sulphated GAG distribution was found to mirror that described previously for collagen, being highest in the gum-pad region and adjacent to alveolar bone. This changed markedly in relation to periodontal disease. Early disease-related changes in GAGs were first detected adjacent to alveolar bone. In severely diseases tissue, an overall increase in sulphated GAG, particularly in the gum-pad region, was present. Increasing disease severity was accompanied by a decrease in dermatan sulphate and a concomitant increase in the proportion of chondroitin-4-sulphate. These changes may be due to the combined effects of chronic inflammation and alterations to the mechanical loading of the tissue owing to loss of attachment.

Animals↗
PubMed1991

Effect of periodontal disease ("broken mouth") on the distribution of matrix macromolecules in the sheep periodontium.

A topographical, biochemical analysis of the soft connective tissues of sheep periodontia diagnosed clinically as showing periodontitis was carried out and compared with healthy periodontal tissue. Protein content was mapped on a site-to-site basis and compared with the distribution of collagen for both healthy and diseased tissue using amino acid analysis. Diseased tissue was more biochemically homogeneous than corresponding healthy tissue. Protein content per cent was in general greater but collagen content was greatly reduced. Tissue adjacent to radicular cementum appeared to be most markedly affected by the disease process. The apparent selective loss of non-proteinaceous components along with loss of collagen attachment may explain the direction in which periodontal disease is propagated through the tissue.

Amino Acids↗
PubMed1990

A longitudinal study of the cultivable subgingival anaerobic bacteria isolated from sheep during the development of broken mouth periodontitis.

In a longitudinal bacteriological study of the cultivable subgingival anaerobic flora isolated from developing broken mouth periodontitis in sheep, samples were taken from five sheep on each of three farms on seven occasions over a period of 2.5 years. Ten different bacterial genera were isolated regularly but with fluctuating frequencies. Bacteroides and Fusobacterium organisms accounted for nearly 70% of the isolates. The Bacteroides and Fusobacterium isolates studied in detail from one farm were identified to species level. The fusobacteria comprised F. nucleatum-like organisms (68.6%). F. necrophorum (29.6%) and F. naviforme (1.8%). The Bacteroides spp. were divided into 11 main groups and included black-pigmented species similar to B. asaccharolyticus and B. gingivalis. On the farm studied in detail, the sheep could be allocated to two groups according to progression of periodontal disease. Most of the B. gingivalis-like isolates were from sheep with actively progressing disease, indicating that this organism may play a role in periodontal destruction in sheep.

Animals↗
PubMed1979

Measurement of regional lung function by tetrapolar electrical impedance plethysmography.

This study demonstrates the clinical feasibility of atraumatically measuring dynamic regional lung function with tetrapolar electrical impedance plethysmography (EIP) in the pediatric age group. A tetrapolar electrode system was used because of its ability to detect local baseline and pulsatile impedance changes, minimal electrode-tissue impedance interference, and uniform current distribution. Studies performed on 4 children 4 to 15 years old with various pulmonary diseases are presented. The information obtained on their regional ventilation and pulsatile perfusion by EIP was found to agree closely with pulmonary ventilation and perfusion scans. In one case, EIP detected pulsatile perfusion abnormalities which were not apparent in the non-pulsatile perfusion scan but were demonstrated by cineangiography. It is concluded that tetrapolar EIP can provide safe, reliable regional information about ventilation and perfusion in diseased lungs, and because of its atraumatic approach, is technically most suitable for use in children.

Adolescent↗
PubMed1978

Functional morphology of the periodontal ligament in the incisor region of the sheep.

The morphology of the periodontal ligament round the sheep incisor tooth is described. Thick, undecalcified sections (100 mum) allow separation of the collagenous fibres into distinct fibre groups and these are compared to similar groups found in other animals. The relationship between the forces applied to the teeth and the distribution of the fibre groups is discussed and it is concluded that there is a functional relationship between the two.

Animals↗