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Biomedical subjects

J R Heath

Publications and source records attributed to J R Heath.

At least 73 records · Page 4Linked to original sources
PubMed1981

The effects of sustained lung inflation on the pattern of breathing in man.

1. Continuous positive-pressure breathing (CPPB) at airway pressures of 0.65-1.00 kPa above ambient pressure has been used to produce a sustained inflation of the lungs of approximately 1 litre in six normal male subjects. 2. Lung inflation produced a reduction in the ventilatory response to carbon dioxide inhalation by slow rebreathing in oxygen over approximately 45 min, with a reduction in the slope of the VE/Pet,CO2 and VT/Pet,CO2 relations (Pet,CO2, = end-tidal PCO2). 3. The pattern of breathing is altered, so that for any given expired minute ventilation (VE), tidal volume (VT) is reduced with a fall in breath duration (Tt) resulting from a decrease in inspiratory time (Ti) with no change in expiratory time (Te). 4. The break point on the VT/Ti relation is lowered.

Adult↗
PubMed1981

Effect of tumors on the concentration of leucogenenol in the serum of mice.

It was found that inoculation of several strains of mice with several types of tumor cells resulted, within 24 hr, in a significant decrease in the serum leucogenenol levels of the mice. Serum leucogenenol levels of the mice inoculated with tumors that are rejected become normal or temporarily above normal at approximately the time the tumor is observed to be rejected. Contrariwise, serum leucogenenol levels of mice inoculated with tumors that are not rejected remain at significantly lower than normal levels during the life of the mice. Unlike tumors, skin allografts increase serum leucogenenol levels. When tumors are rejected because of the previous immunization of the mice, serum leucogenenol levels become normal at approximately the time the tumor is observed to be rejected. Excision of the tumor after 1 week of growth, with the consequent recovery of the mice, is accompanied by a recovery of normal serum leucogenenol levels. Also, it was found that injection of mice with a cell-free 0.9% NaCl solution extract of a tumor results in a temporary decrease in serum leucogenenol levels comparable to that observed with the inoculation of a viable tumor which lasts from 24 to 96 hr. It is suggested that the suppression of serum leucogenenol levels is one of the factors responsible for the immunosuppression associated with a growing tumor.

Animals↗
PubMed1980

Royal Naval dockyards asbestosis research project: nine-year follow-up study of men exposed to asbestos in Devonport Dockyard.

Progression of asbestos-related disease was assessed in a group of 253 dockyard workers examined in 1966 and 1975. Despite the almost complete protection from exposure to asbestos since 1966, radiographic parenchymal abnormalities increased and occurred more frequently during the next 9 years in those men who had been more heavily exposed to asbestos. Lung function values were lower in those most heavily exposed and were declining at a faster rate than in those with less dust exposure. The most sensitive lung function index was the transfer factor.Those men with persistent crackles in 1966 exhibited a restrictive pattern of lung function, whereas an obstructive pattern was seen in men with wheezes in 1966. The men with irregular small opacities of category 1/1 or more or with diffuse pleural change in 1966 and who survived to 1975 had worse lung functions than any other groups.Progression of disease was greater for smokers than non-smokers, with those who gave up smoking between 1966 and 1975 suffering the greatest changes. This latter group showed most increase in small opacities and included almost all new cases of diffuse pleural changes. They also showed the greatest declines in forced expiratory volume and forced vital capacity.

Asbestos↗
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↗
PubMed1974

Functional residual capacity during anaesthesia. II. Spontaneous respiration.

Functional residual capacity has been measured by helium dilution in 26 spontaneously breathing patients before and immediately after anaesthesia, which was induced with thiopentone and maintained with halothane. The mean reduction was 390 ml (16.1% or pre-induction value) and the change was highly significant (P less than 0.001). The decrease in FRC correlated with age (r equals 0.41: P less than 0.005) and less (P less than 0.001). The decrease in FRC correlated with age (r equals 0.41; P less than 0.005) and less satisfactorily with the weight/height ratio (r equals 0.31; P less than 0.05) which itself correlated with age. Inspired oxygen concentration, expiratory reserve volume and the presence of phasic expiratory muscle activity bore no significant relationship to the decrease in FRC. There was no evidence of any progressive change in FRC between 6 and 20 min after the induction of anaesthesia.

Adult↗