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Biomedical subjects

J R Heath

Publications and source records attributed to J R Heath.

13 recordsLinked to original sources
PubMed1991

Evaluation of biodegradable ampicillin anhydrate microcapsules for local treatment of experimental staphylococcal osteomyelitis.

Successful treatment of chronic osteomyelitis requires sustained high concentrations of antibiotics locally within the infected bone. The efficacy of biodegradable (poly-DL-lactide-co-glycolide) microspheres containing 30.7% ampicillin anhydrate for the local treatment of experimental staphylococcal osteomyelitis was evaluated in rabbits. In the initial experiment, antibiotic therapy was initiated immediately following injection of Staphylococcus aureus into the proximal tibial metaphysis. A single intramedullary injection of microencapsulated ampicillin (100 mg) prevented osteomyelitis in all seven animals tested and was as effective as a two-week course of parenteral ampicillin administration. When antibiotic therapy was delayed for seven days, osteomyelitis developed in four of eight animals treated locally with microencapsulated ampicillin and in six of eight animals that received parenteral ampicillin therapy. When antibiotic therapy was delayed for seven days and was preceded by debridement, all ten animals treated locally with microencapsulated ampicillin had sterile bone cultures. In contrast, seven of ten animals treated locally with unencapsulated ampicillin powder developed osteomyelitis. Biodegradable antibiotic-loaded microspheres may be of clinical benefit for the local treatment of chronic osteomyelitis.

Ampicillin↗
PubMed1976

Abrasion of restorative materials by toothaste.

The procedure developed in this investigation is suitable for determining the abrasion resistance of restorative materials to toothbrush/dentifrice abrasion. Ideally, a restoration should have an abrasion resistance similar to that of enamel. Of the materials tested, gold was the only one that wore slightly less than enamel, whilst amalgam wore almost twice as quickly. The silicate material and composites (excluding TD.71) wear away 2-4 times faster than enamel. TD.71 and especially the unfilled resin exhibited very high rates of abrasion. After prolonged toothbrush/dentifrice abrasion, the surfaces of gold and amalgam were considerably smoother than those of the silicate and composite materials.

Dental Amalgam↗
PubMed1975

Enzyme activities and properties of lysosomes and brush borders in jejunal biopsies from control subjects and patients with coeliac disease.

1. Reduced activities of four enzymes from brush borders were found in intestianl biopsies from patients with untreated coeliac disease. The activities returned towards control values after treatment by gluten withdrawal. Parallel changes were noted for the cytosol enzyme lactate dehydrogenase. 2. Measurement of brush-border integrity by differential centrifugation of biopsy extracts indicated increased fragility of the brush borders in biopsies from untreated patients. Normal values were obtained for biopsies from treated patients. 3. Increased activites of six acid hydrolases (lysosomal enzymes) were found in biopsies from untreated coeliac patients. Normal values were obtained for biopsies from treated patients. 4. Assement of lysosomal integrity by assay of latent N-acetyl-beta-glucosaminidase and of sedimentable activity of four acid hydrolases demonstrated increased lysosomal fragility in untreated coeliac mucosa. These lysosomal changes return to within the normal range after treatment by gluten withdrawal. 5. The lysosomal changes are consistent with their having a pathogenic role in the enterocyte damage of coeliac disease. Possible mechanisms for the lysosomal changes are discussed.

Acetylglucosaminidase↗
PubMed1975

Effect of bile-duct ligation on organelle marker enzymes in the liver and serum of rats.

1. Marker enzymes for the principal subcellular organelles of rat liver were asayed in the liver of rats 1 day and 8 days after bile-duct ligation or after laparotomy as a control procedure. 2. The microsomal enzymes in liver tissue showed complex changes. Benz[alpha]pyrene hydroxylase activity, predominantly found in the smooth endoplasmic reticulum, was decreased. Glucose 6-phosphatase activity and ribonucleic acid, which are localized predominantly in the rough endoplasmic reticulum, were increased. 3. The plasma membrane enzyme, alkaline phosphatase, increased in activity after bile-duct ligation. 4. No changes in mitochondrial enzyme activities were noted after 1 day but there was a 50% reduction 8 days after ligation. Lysosomal enzyme activities did not change in the liver tissue. 5. Liver catalase and D-amino acid oxidase activities showed a slight increase at 1 day postligation but a significant fall by 8 days. 6. Lactate dehydrogenase, a cytosol enzyme, showed a decrease in activity after 1 day but an increase in tissue activities 8 days after ligation. 7. Serum activities of mitochondrial, plasma membrane, microsomal, lysosomal and cytosol marker enzymes tended to increase post-ligation, particularly at 8 days. 8. Monoamine oxidase, a predominantly mitochondrial enzyme, was greatly elevated in the serum after 1 day but had returned to normal activities by 8 days.

Acetylglucosaminidase↗