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At least 199 records · Page 11Linked to original sources
PubMed2001

The CEEF, closed ecosystem as a laboratory for determining the dynamics of radioactive isotopes.

Nuclear power generation is now confronted with a very difficult situation all over the world because of the problems of radioactive waste disposal and of the accidents, which have occurred. Nuclear power generation now supplies nearly 30% of total electric power demand in Japan. Therefore it is very difficult to change quickly the construction plans of nuclear facilities already designed. A nuclear fuel reprocessing center is now under construction in Rokkasho-Mura in Aomori Prefecture. If this center starts its operation, small amounts of 14CO2 are expected to be released into the atmosphere and will enter the global cycle. The simulation experiment of 14C trace amounts which enter into ecosystems is now being planned using stable isotope 13C within CEEF (Closed Ecology Experiment Facilities).

Air Pollution, Radioactive↗
PubMedDate not supplied

Radioactive isotope labeled diffusible components of a bone morphogenetic substratum.

Bone matrix gelatin labeled with radioactive glucose, cysteine, proline, tyrosine or tryptophan was enclosed in one chamber while an adjoined second chamber was left empty to become filled with interstitial fluid. The paired diffusion chambers were implanted into the anterior abdominal wall of allogeneic rats for 14 days. Release of the matrix gelatin (BMG) from the loaded chamber was followed by a bone formation on the outer membrane of the unloaded chamber. 3H-cysteine labeled components of BMG were disseminated into the interstitial fluids and throughout the host tissues 5 times more rapidly than 3H-proline labeled BMG. The relative rates of loss of radioactivity from the residue was cysteine greater than tryptophan greater than tyrosine greater than proline. Electron microscopic autoradiography revealed random dissemination of collagenous and non-collagenous derivatives of BMG. 3H-glucose distribution was coordinated with ruthenium red staining coarse granules and may have originated from BMG. A component of interstitial fluid staining positively with Coomassie brilliant blue and PAS methods was identified by SDS polyacrylamide gel electrophoresis of interstitial fluid aspirated from empty chambers attached to chambers loaded with bone matrix gelatin. The character of the bone morphogenetic property in bone gelatin has not yet been defined in physico-chemical terms but present evidence points to the view that it is associated with a protein molecule.

Animals↗
PubMed2003

Estimation of animal transfer factors for radioactive isotopes of iodine, technetium, selenium and uranium.

In post-closure radiological safety assessments of repositories for solid radioactive wastes, transfers of radionuclides to animal products are typically characterised using Transfer Factors (TFs), defined as the ratio of the concentration of the radionuclide in the animal product of interest to the rate of intake in diet. Such transfer factors can be measured directly in experimental studies, but they can also be estimated by use of biokinetic models for uptake and retention of radionuclides in animals. Based on a review of the literature, biokinetic models have been developed for the uptake and retention of iodine, technetium, selenium and uranium. These biokinetic models allow TF values to be estimated for different types of animals and for different animal lifetimes. For each radionuclide considered, reference values and ranges of TF values are estimated. These are summarised in Table 1.

Animals↗