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Biomedical subjects

J M Allen

Publications and source records attributed to J M Allen.

At least 271 records · Page 15Linked to original sources
PubMed1977

Autooxidation as a basis for altered function by polymorphonuclear leukocytes.

To investigate the possibility that human polymorphonuclear leukocytes (PMN) elaborate sufficient amounts of hydrogen peroxide (H2O2) and other radicals of reduced oxygen to be autotoxic and retard directed cell movement and phagocytosis, the rate of ingestion of opsonized lipopolysaccharide-paraffin oil particles and movement through Nuclepore filters were studied. Ingestion rates were increased under anaerobic conditions and in normal aerobic conditions in the presence of extracellular catalase but not superoxide dismutase (SOD) or scavengers of singlet oxygen or hydroxyl radicals. Conversely, ingestion rates were decreased when cells were exposed to H2O2 or a superoxide anion (O2-)-H2O2 generating system of xanthine-xanthine oxidase. Catalase, but not SOD, prevented the effect and also enhanced the directed movement of PMN in normal aerobic conditions. PMN from volunteers administered 1600 U/day of the membrane lipid antioxidant alpha-tocopherol were hyperphagocytic but killed Staphylococcus aureus 502A less effectively than controls, suggesting that less H2O2 was available to damage PMN or kill bacteria. H2O2-dependent stimulation of the hexose monophosphate shunt, H2O2 release from phaogytizing PMN, and fluoresceinated concanavalin A cap formation promoted by H2O2 damage to microtubules were all diminished, but the release of O2- from phagocytizing PMN was not diminished in the vitamin E group. These results support the hypothesis that directed movement and phagocytosis by PMN are attenuated by autooxidative damage to the cell membrane by endogenously derived H2O2 and that the administration in vivo of vitamin E may prevent this damage by scavenging H2O2.

Aerobiosis↗
PubMed1975

Scanning electron microscopy of normal and abnormal exfoliated cervical squamous cells.

The surface ultrastructure of normal, malignant and dyskaryotic exfoliated cervical squamous cells was examined with the Scanning Electron Microscope (SEM). Normal and malignant cells were found to have very similar surfaces to those seen on similar cells in a biopsy specimen. Dyskaryotic cells, however, showed a large range of surface features and dyskaryotic cells that looked identical at light microscopy could be subdivided into three groups by examining their ultrastructural features.

Biopsy↗
PubMed1975

Surgical prophylaxis of subluxation and dislocation of the hip in cerebral palsy.

The clinical and radiological state of the hips of a group of children with cerebral palsy treated without operation is compared with that in a group treated by operation to correct adduction and flexion deformity and to obtain balanced action in the hip muscles. In the first group, 11 per cent of hips were dislocated, 28 per cent subluxated, 46 per cent dysplastic and 15 per cent normal. In the second group no hip was dislocated, 13 per cent were subluxated, 35 per cent dysplastic and 52 per cent normal. Surgical intervention is indicated clinically for a range of abduction diminishing to less than 45 degrees and--on radiological criteria--for early dysplastic changes, especially a break in Shenton's line, irrespective of the patient's age, severity of involvement or neurological maturity. Prevention of subluxation or dislocation improves function and diminishes the liability to develop a painful hip in adolescence or early adult life.

Adolescent↗
PubMed1969

Allantoinase: association with amphibian hepatic peroxisomes.

Differential and density-gradient centrifugation studies have estaiblished an associatiotn between allaintoinase and peroxisomes from the liver of the frog Rana pipiens. The presence of allantoincase in the peroxisome indicates. a iricolytic function for this orgainelle in the liver of amphibians.

Acid Phosphatase↗