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Biomedical subjects

C W Mays

Publications and source records attributed to C W Mays.

At least 91 records · Page 5Linked to original sources
PubMed1976

90Sr + 90Y bremsstrahlung efficiency predicted for humans.

Bremsstrahlung x-rays are produced when energetic beta-particles are emitted and absorbed. Measurements of total-body bremsstrahlung efficiencey (x-ray photon output per muCi 90Sr in the body, relative to that in water) have been made in the intact mouse, rat, rabbit, and dog sacrificed 2 weeks after the injection of 90Sr + 85Sr. Efficiencies were determined by a comparison of the bremsstrahlung output from 90Sr + its daughter 90Y and the gamma-ray emission of 85Sr. Results were checked by a beta-assay of the ashed animals. Bremsstrahlung efficiencies averaged 1.10 in a 0.04 kg mouse, 1.14 in a 0.13 kg rat, 1.23 in a 2.6 kg rabbit, and 1.32 in an 8.5 kg beagle. Extrapolating to a 70 kg human, a relative bremsstrahlung efficiency of about 1.4 is predicted. An estimate was made of the 90Sr body content in a former dial painter based on in vivo counting and a bremsstrahlung efficiency of 1.39 predicted for a 55 kg human female by these animal data. Our value of 1.42 +/- 0.08 muCi 90Sr was in good agreement with corresponding results reported for this subject by 8 other laboratories.

Animals↗
PubMed1976

Ca-DTPA-induced fetal death and malformation in mice.

Increased fetal mortality and congenital malformation were induced in mice by Ca-DTPA, a chelate widely used for the removal of internally deposited plutonium in human beings. Mated C57BL/Do female mice were given five daily injections of 720-2,880 mumol/kg Ca-DTPA during early, mid, or late gestation. Damage probably occurred as a result of the depletion by Ca-DTPA of zinc and manganese, trace elements essential to growth and development. By extension, it seems likely that Ca-DTPA could damage human fetuses. A much safer chelate, Zn-DTPA, is recommended for the treatment of accidental plutonium contamination.

Abnormalities, Drug-Induced↗
PubMed1976

Mammary neoplasia in a closed beagle colony.

The incidence rate of mammary neoplasia in a large colony of beagles and the relationship to internal skeletal and/or liver radiation, age, relatively late ovariectomy (4 years and older), endometritis, parity status, and adrenal weight were examined. Of these various factors, age was the only condition that was clearly correlated with changes in the mammary tumor incidence. The rate became significant at approximately eight years of age and increased progressively throughout the older age classes. Among the female dogs, the incidence of mammary cancer was higher than that of any other form of spontaneous malignancy.

Adrenal Glands↗
PubMed1975

Determining liver retention of transuranium elements in living beagles.

A method has been developed whereby the liver content of photon-emitting transuranium elements can be determined in living beagles by a combination of total-body and partial-body counting. Calibration of the system was accomplished through the photon counting of intact dogs and also of the parts of the same animals following autopsy. A determination of the calibration factors for 252Cf, 247Cf, 243Cm, 237Pu, and 241Am has been made. The special case of 252Cf was treated in which a significant fraction of the high energy fission gamma-ray spectrum penetrates the Pb shield employed in partial-body counting, and methods were developed which allow for this effect in the calculation of liver content. Some uniformity of response in the system was evident for all of the emitters which were considered. It is proposed that similar techniques could be applied in the determination of selected organ radioactivity in other species including man.

Americium↗