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Biomedical subjects

C E Webber

Publications and source records attributed to C E Webber.

At least 109 records · Page 6Linked to original sources
PubMed1975

Abnormal brain scans: Contribution of blood radioactivity to image.

Images obtained with 99m-Tc-labeled red blood cells were compared with 99m-Tc-pertechnetate scans in 26 patients with primary and secondary brain tumors, intracerebral infcts, and hemorrhage. The results indicated that the contribution of blood pool radioactivity to a positive brain scan was minor.

Astrocytoma↗
PubMedDate not supplied

An improved multi-element measurement of mineral absorption in the piglet utilizing the fecal monitoring technique.

The fecal monitoring technique for measuring the absorption of Zn, Mn, Se, and Fe was studied in eight male piglets (mean +/- SEM birthweight (bw) = 1695 +/- 50 g) using high resolution gamma spectrometry. Four d old piglets were fed a complete liquid milk diet for five d prior to the orogastric administration of an isotope dose (75Se, 54Mn, 59Fe, and 65Zn) equilibrated with the liquid milk diet. 51CrCl3 was used as a fecal marker but was found to be partially absorbed. Stool samples were collected daily for 15 d, counted, and then the daily fecal excretion was calculated. Results indicate that endogenous excretion for each of the isotopes was not constant but decreased exponentially with time. The pattern of endogenous excretion varied between elements. An improved method for calculating the endogenous excretion was therefore developed. This method is based on the pattern of endogenous excretion in three-four d old male piglets (mean +/- SEM bw = 2060 +/- 75 g) injected intravenously with the same isotopes and on the level of endogenous excretion in orally fed animals in the postabsorptive phase of excretion. These findings have important implications for the estimation of endogenous excretion in future fecal monitoring absorption studies in order to minimize underestimation of true absorption.

Absorption↗
PubMedDate not supplied

In vivo X-ray fluorescence (XRF) measurement of uranium in bone.

This study investigates the applicability of X-ray fluorescence (XRF) to measuring bone uranium concentrations, using a 57Co source to excite the uranium X-rays, with the source and detector in an approximate 180 degrees backscatter geometry relative to the sample position. It is demonstrated, by experiment and Monte Carlo simulation, that the X-ray to coherent peak ratio is linearly related to concentration and is independent of variations in source-sample geometry, thickness of overlying tissue and tibia size. Preliminary in vivo measurements indicate a minimum detectable concentration (MDC) of approximately 20 micrograms/g, which may not be sufficiently sensitive for monitoring occupational workers. However, a larger study of occupationally exposed individuals as well as work with subjects with known significant accidental uranium exposures is necessary to assess the clinical usefulness of this system.

Bone and Bones↗
PubMedDate not supplied

Photon scattering measurement of calcaneal bone density: result of in vivo cross-sectional studies.

The density of trabecular bone in the os calcis has been measured in 321 subjects using a gamma ray scattering technique. In normal subjects it was shown that density could be predicted from body weight and age with a standard error of 5.6%. It was also shown that the dependence of density upon weight and age was the same for both sexes. When the os calcis had been subjected to a greater than normal mechanical stress by either increased physical activity or excessive body weight, trabecular bone density was increased. Density was measured in 128 patients in whom the incidence of skeletal demineralization was expected to be greater than that in control subjects. Some significant reductions in density were observed. It is projected that density measurements might be of value in those situations where, in response to metabolic stress, the rate of loss of mineral from trabecular bone is greater than that from cortical bone.

Adult↗