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E R Humphreys

Publications and source records attributed to E R Humphreys.

33 records · Page 2Linked to original sources
PubMed1978

The relationship between 59Fe uptake in marrow and 239Pu deposition in bone.

The marrow in the left femur of each of 17 mice was destroyed by X-irradiation and 59Fe and 239Pu uptake into both femurs was measured 1, 3 and 7 days later. Uptake of 59Fe into marrow was depressed in the left femur 1 and 3 days after irradiation but was enhanced in the right unirradiated femur 3 days after the left femur was irradiated. There was no corresponding depression of 239Pu uptake into the left irradiated femur or enhancement into the right unirradiated femur. These results do not support the view that a functioning erythropoietic marrow is necessary for 239Pu to be deposited in bone.

Animals↗
PubMed1977

The measurement of blood flow in mouse femur and its correlation with 239Pu deposition.

The concentration of 18F was measured in three parts of the femur and in the blood of 36 mice killed at intervals of from 1 min to 2 h after intravenous injection. Blood supply to the bone sections, calculated by dividing the increase in 18F concentration in bone by the integral of 18F concentration in blood between selected time intervals, was shown to be unaffected by the return of 18F from bone to blood at times earlier than 90 min following injection. The supply of blood per unit mass of bone was greatest in distal end of the femur, less in proximal end and least in shaft. In whole femur average blood flow was 230 mm3 per gram fresh bone per min. The deposition of 239Pu in three parts of the mouse femur was shown to be linearly related to blood flow and the nature of the relationship is discussed.

Animals↗
PubMed1976

Cytogenetic effects of protracted exposures to alpha-particles from plutonium-239 and to gamma-rays from cobalt-60 compared in male mice.

Adult C3H X 101 hybrid male mice were injected intravenously with 4 muCi of 239Pu citrate per kg body weight and examined for evidence of cytogenetic damage to the testis after exposures of 21, 28 and 34 weeks, with average doses from alpha-particles estimated as 13, 18 and 18 rad respectively (mean dose rate 0.00006 rad/min). Results were compared with those obtained when equivalent males were exposed continuously and concurrently to 1128 rad 60Co gamma-irradiation over 28 weeks (0.004 rad/min). The following estimates of the relative effectiveness of the alpha- and gamma-radiation were made: 24 for reciprocal translocations and for chromosome fragments, 22 for dominant lethal mutations acting after implantation. These values (with mean of 23) are based on average testis doses, with no correction for probable non-homogeneity of alpha dose distribution. In the mice exposed to gamma-irradiation there were significant reductions in testis mass and epididymal sperm-count. Although corresponding differences from control were not significant in the alpha series, consideration of results from a previous experiment by the same authors [2] allowed the relative effectiveness of the alpha- and gamma-irradiation for testis mass reduction to be estimated as roughly 10-15. Existing data on translocation induction in mouse spermatogonia by low dose-rates of gamma-rays (down to 0.003 rad/min) were analysed. They suggested that minimum rates of induction at very low intensities were not less than 1 X 10(-5) translocations per rad. A comparison of the frequencies of induction of fragments and of sperm-head abnormalities obtained after chronic gamma-ray exposures in the present experiment with those found by other workers after acute X-ray exposures suggested that there were no marked dose-rate effects with these types of mutational effect. Finally, the special problems associated with cytogenetic studies on alpha-emitters are discussed.

Alpha Particles↗
PubMed1975

Radiation dose from plutonium deposited in marrow and bone of normal and chimaeric mice.

239Pu citrate was injected intraperitoneally into CBA mice and into CBA mice which had been made chimaeric by replacing their haematopoietic bone-marrow with that from another genetically-identical but cytologically-distinct strain. The mice were killed at three intervals up to 90 days after injection, and the deposited 239Pu was determined radiochemically in bone-marrow and in bone. The average radiation dose (integrated over 90 days) was found to be greater in the bones but lower in the marrow of chimaeric mice than in the corresponding tissues of the normal CBA mice. These results are discussed from the points of view of induction of malignant change in marrow and bone and of plutonium metabolism in the two types of mouse.

Animals↗