Biomedical subjects

P W Todd

Publications and source records attributed to P W Todd.

12 recordsLinked to original sources

PubMed1993

Effects of spaceflight on the musculoskeletal system: NIH and NASA future directions.

Prolonged bed rest, undertaken by volunteers or resulting from injury and disease, can impair bone and muscle function and structure; extended travel in space also induces these effects. Fluid shifts and disrupted fluid balance may also contribute to observed musculoskeletal aberrations in the weightless environment. Some molecular and cellular events involved in the loading and unloading of the musculoskeletal system are under neural and endocrine influence or control, whereas other events are influenced by local growth factors. Studies are in progress to develop interventions that preserve or improve musculoskeletal integrity in 1g. The NIAMS and NASA are interested in basic and clinical studies of the influence of microgravity on the musculoskeletal system. The interagency workshop results form the basis for new collaborative and cooperative research emphases for the biomedical community under a broad agreement between the National Institutes of Health and NASA.

Bone and Bones↗

PubMed1983

Differing electrical surface charge and transplantation properties of genetically variant sublines of the TA3 murine adenocarcinoma tumor.

Comparative measurements have been made of the transplantation and electrical surface charge properties of the near-diploid TA3-Ha ascites tumor and a new hypotetraploid ascites subline designated TA3-L. The negative surface charge density and the density of electrophoretically detectable sialic acid residues were determined to be twice as great for TA3-L as TA3-Ha cells. The two TA3 sublines were found to have identical growth properties in isogeneic mice and to exhibit progressive growth in three allogeneic strains of mice. The lethal tumor cell inoculum in allogeneic mice was lower in all cases for the TA3-L cells. From a comparison of several TA3 ascites tumor sublines, it can be concluded that their transplantability into allogeneic strains of mice is correlated with the density of negative surface charge but is independent of the degree of tumor aneuploidy.

Adenocarcinoma↗

PubMed1979

Surface charge in foreign body carcinogenesis.

The importance of surface charge in foreign body carcinogenesis was evaluated by implanting in C3H/HeJ male mice, bipolar polystyrene thermoelectrets formed in variously charged electrical fields. Charged electrets had tumor rates similar to control groups. The cumulative probability of tumor development was highest in the charged electret group being 0.58 at 133 weeks after implantation. The tumor rate for all charged electrets was 27% as compared to 17% and 6% for the control groups. The latent period of tumor induction varied little between groups and averaged approximately 700 days. No conclusions regarding the tumorigenic effect of electropositive versus electronegative sides of the electret were made although the majority of tumors arose on the electronegative (body) side of the electrets. An occasional tumor (2/25) arose on both sides of a single electret. The antigenicities of tumors tested by excise and challenge techniques were weak. The immunologic relationship between top and bottom growing tumors on a single electret could not be adequately determined because of the weak antigenicity.

Animals↗

PubMed1979