Publications by authors named "Kirchmann R"

The project "Sunshine" was originally focused on the study of strontium 90 from the world-wide radioactive fallout and its effects on man. It was one of the most important projects the USAEC had ever had. It was being conducted as a scientific study, the primary purpose of which was to discuss the scientific truth and present the facts publicly.

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Combined treatment with trypsin, cholesterol esterase, and neuraminidase transforms LDL, but not HDL or VLDL, to particles with properties akin to those of lipid extracted from atherosclerotic lesions. Single or double enzyme modifications, or treatment with phospholipase C, or simple vortexing are ineffective. Triple enzyme treatment disrupts the ordered and uniform structure of LDL particles, and gives rise to the formation of inhomogeneous lipid droplets 10-200 nm in diameter with a pronounced net negative charge, but lacking significant amounts of oxidized lipid.

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The movement through the environment and the toxicity to plants of 99Tc have been studied. However, information is scanty on 99Tc toxicity to mammals even though this is the decisive criterion for assessing the consequences of releases of Tc. A critical tissue could be the thyroid because of its preferential accumulation of Tc and the developing organism because of its greater radiosensitivity; moreover, this toxicity might be enhanced under conditions of a low iodine (I) diet.

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The objective of this paper is to evaluate the dose to man from releases of 99Tc in a fresh water system and to identify the biospheric transfer parameters to which the total dose is the most sensitive. Only internal exposure is taken into account, as the external irradiation leads to a negligible dose contribution. Two release modes were considered: continuous (routine) releases and accidental releases.

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Technetium (Tc) released into the environment can reach animals in various chemical forms: as pertechnetate (TcO-4) in drinking water or deposited on the surface of vegetables and forage plants, or as Tc bioincorporated into plants and associated with various plant constituents. In addition to being influenced by chemical speciation in the diet, absorption, metabolism, and retention of Tc in animals are modified by the treatment that the alimentary bolus undergoes during its passage through the gastrointestinal tract. This behavior differs markedly between polygastric and monogastric animals.

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Two lactating cows were given tritiated hay containing organically bound tritium (OBT) only for about 4 weeks. Tritium activity was determined in milk fat, casein, lactose, milk water, and whole milk. In one cow, milk was sampled for approximately 450 days, covering two lactation periods.

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Different radionuclides which can be released by nuclear installations (Na2(51) CrO4 , 54MnCl2 , 59FeCl3 and 60CoCl2 ) were given to lactating dairy cows either orally or by intravenous (i.v.) injection.

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A research programme on the transfer of tritium in the food chain has been in progress for several years on the experimental farm of the Nuclear Energy Research Center at Mol. The studies reported here are related to the distribution of tritium in the organs of farm animals contaminated in various ways. Two young male calves ingested tritiated milk; the daily intake of 3H-organic form was about 15 muCi for each calf and the total activity ingested until the sacrifice was 482 muCi.

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Freshwater and marine algae are particularly useful for studying the radioactive contamination of aquatic systems. Acetabularia, Chlamydomonas and Porphyra were used to investigate the uptake and eventual biological effects of tritium. When the Acetabularia are grown in the presence of tritiated water, a significant amount of 3H is incorporated in the total nucleic acids and protein fraction.

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The paper presents the results of an experimental investigation designed to study the trend of the contamination by radiocesium of milk and meat of cows: (1) under conditions of a single contamination of the pasture. (2) under conditions of a continuous ingestion corresponding to the case of a constant contamination of the pasture. The knowledge of the evolution in the course of time of the relation between the activities of meat and milk and of its dependence on the nature of the different organs and the age of the animals should make more easy the survey of the contamination of the environment and allow to decide on possible countermeasures to be taken in the case of an accident.

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