Search PubMed⌕ Search

Biomedical subjects

E L Lloyd

Publications and source records attributed to E L Lloyd.

At least 37 records · Page 2Linked to original sources
PubMed1984

The effects of sera from Ra dial painters on the mitogenic responses of normal human lymphocytes.

Sera from former Ra workers were incubated with normal human lymphocytes and the effects produced in stimulation assays with specific mitogens were compared with those observed with incubation using normal human sera. The sera from the Ra workers with high residual body burdens (greater than 0.1 muCi 226Ra) inhibited normal control lymphocytes stimulated with Con A and PHA when compared with control homologous sera. Although a significant suppression was not obtained between high- and low-body-burden groups a trend was indicated. Sera from the highest body-burden worker (0.58 muCi) was inhibitory to all normal lymphocyte populations tested regardless of the mitogen stimulant employed.

Adult↗
PubMed1983

Measurement of lymphoblastogenic activity from thorium workers.

Mitogenic stimulation of peripheral blood lymphocyte cultures obtained from 36 thorium workers was studied to determine whether the response of these cells was affected by the individuals' occupational exposure to alpha irradiation. The standard assay involved incubating 2 X 10(5) lymphocytes per test well for 72 hours in the presence of phytohemagglutinin (PHA), concanavalin A (Con A) or pokeweed mitogen (PWM). The results showed that there was a significant decrease in lymphocyte responsiveness of former thorium workers grouped by decade of life when compared with controls of the same decade of life for each mitogen tested with the exceptions of PHA in the 41-50 age group and PWM in the 51-60 age group. We are unable to correlate the decreased response observed with the measured body burdens, external gamma exposure, or thoron exhalation rates in these thorium cases. However, other occupational exposures (i.e., various chemicals used in processing thorium) cannot be eliminated as a possible cause.

Adult↗
PubMed1983

Cells at risk for the production of bone tumors in radium exposed individuals: an electron microscope study.

The endosteal cells of bone from a 75-yr-old woman who had acquired radium internally, as a consequence of her previous employment as a radium dial painter, are documented here for the first time by electron microscopy. As a result of amputation for a fibrosarcoma in the region of the right knee joint, fresh samples of bone and tumor tissue from the femur were made available. A sample of bone, also obtained at amputation from an unirradiated control patient, age 65, was examined from the same site in the femur. A comparison of the bone-marrow interface from the two patients showed that, unlike the control bone where cells were seen close to bone mineral a fibrotic layer was interposed between the marrow cells and the bone mineral in the bone from the radium case. This layer varied in thickness up to 50 microns and was often acellular, although cell remnants and cells, which appeared viable, were sometimes seen within this layer. It is suggested that irradiation of those cells proliferating within, and at the edge of, this replacement fibrotic layer may be the most important in the induction of bone tumors rather than the original cells lying within the 0-10 microns range from bone mineral which has previously been supposed. The nuclear dimensions of the endosteal bone lining cells and their distance from bone mineral have been measured in the bones from the radium and control cases. These dimensions are important not only in understanding the mechanisms by which bone tumors arise but in developing models of carcinogenic risks of other alpha-particle emitting isotopes such as plutonium.

Aged↗
PubMed1981

A rational regimen for perioperative steroid supplements and a clinical assessment of the requirement.

Sixty-one patients with rheumatoid arthritis on long-term corticosteroid treatment were managed for 107 orthopaedic procedures using a flexible method of supplementary steroid cover. It was found that the amount actually required was surprisingly small and in 78% of the operations no postoperative supplements were given. There were no consistent factors which would predict a requirement for supplementary steroids in any particular individual.

Adolescent↗
PubMed1981

Morphology of cells malignantly transformed by alpha particle irradiation.

The idea that one alpha particle (with LET approximately 100keV/micrometers) traversing a cell nucleus would kill a cell has been a concept which has been traditionally accepted by most radiation biologists. It was, therefore, difficult to see how alpha radiation could act directly on nuclear DNA to cause cancer. In experiments where mouse embryo cells (C3H 10T1/2) were irradiated with a parallel beam of 5.6 MeV alpha particles from a Tandem Van de Graaff machine, we made the surprising discovery that about 10 to 20 alpha particles through each nucleus were required to kill 2/3 of the cells (Lloyd 1979a). Earlier workers were misled because they failed to make measurements of nuclear areas of the cells as they were irradiated. We have used scanning electron microscopy, both to observe the cells at the time of irradiation and to document the change in unirradiated cellular dimensions as the cells become flattened on conventional tissue culture plates. The present paper also describes the morphological changes observed by SEM between cells which were subsequently transformed to become malignant by alpha irradiation and untransformed control cells.

Alpha Particles↗