Kathy
Well-known member
I thought some of you might find these studies of interest. Both are examples of chronic exposure to uranium via ingestion.
The first study determined that the uranium was only absorbed into the body via the small intestine. Not the mouth (buccal cavity) and not the large intestine (proximal colon). No, only via the small intestine. Interestingly, the distal ileum is part of the small intestine. The distal ileum is classified a specified risk material (SRM).
In this second study, they analysed whether using acute exposure results held true during chronic exposure to uranium. The results did not hold true. Chronic exposure to rats in their drinking water resulted in accummulation of uranium in their teeth and in their BRAINS. It is recommended that chronic exposure modelling be further looked into.
In this third study, acute exposure to depleted uranium (injected intraperitoneally) caused neurotoxic effects. It definitely crossed through the blood-brain barrier.
What is the toxic agent, when prions are ashed? (no protein remains)
This information is important, if you know anybody returning from Iraq or even Afganastan, they should be aware of these "new" findings. Supposedly, some of the states are going to test their soldiers for DU upon their return.
The first study determined that the uranium was only absorbed into the body via the small intestine. Not the mouth (buccal cavity) and not the large intestine (proximal colon). No, only via the small intestine. Interestingly, the distal ileum is part of the small intestine. The distal ileum is classified a specified risk material (SRM).
(1) Int. J. Radiat. Biol. 2005 Jun;81(6):473-82
Absorption of uranium through the entire gastrointestinal tract of the rat.
Dublineau I, Grison S, Baudelin C, Dudoignon N, Souidi M, Marquette C, Paquet F, Aigueperse J, Gourmelon P.
Institut de Radioprotection et de Surete Nucleaire, Direction de la RadioProtection de l'Homme, Service de Radiobiologie et d'Epidemiologie, Laboratoire de Radiotoxicologie experimentale, Fontenay-aux-Roses Cedex, France. [email protected].
The aim was to determine the gastrointestinal segments preferentially implicated in the absorption of uranium. The apparent permeability to uranium (233U) was measured ex vivo in Ussing chambers to assess uranium passage in the various parts of the small and large intestines. The transepithelial electrical parameters (potential difference, short-circuit current, transepithelial resistance and tissue conductance) were also recorded for each segment. Determination of in vivo uranium absorption after in-situ deposition of 233U in digestive segments (buccal cavity, ileum and proximal colon) and measurements of uranium in peripheral blood were then made to validate the ex vivo results. In addition, autoradiography was performed to localize the presence of uranium in the digestive segments. The in vivo experiments indicated that uranium absorption from the digestive tract was restricted to the small intestine (with no absorption from the buccal cavity, stomach or large intestine). The apparent permeability to uranium measured with ex vivo techniques was similar in the various parts of small intestine. In addition, the experiments demonstrated the existence of a transcellular pathway for uranium in the small intestine. The study indicates that uranium absorption from the gastrointestinal tract takes place exclusively in the small intestine, probably via a transcellular pathway.
PMID: 16249162 [PubMed - indexed for MEDLINE]
In this second study, they analysed whether using acute exposure results held true during chronic exposure to uranium. The results did not hold true. Chronic exposure to rats in their drinking water resulted in accummulation of uranium in their teeth and in their BRAINS. It is recommended that chronic exposure modelling be further looked into.
(2) Health Phys. 2006 Feb;90(2):139-147. LWWonline – Lippincott Williams & Wilkins
ACCUMULATION AND DISTRIBUTION OF URANIUM IN RATS AFTER CHRONIC EXPOSURE BY INGESTION.
Paquet F, Houpert P, Blanchardon E, Delissen O, Maubert C, Dhieux B, Moreels AM, Frelon S, Gourmelon P.
* IRSN/DRPH/SRBE Laboratoire de Radiotoxicologie Experimentale, BP 166, 26702 Pierrelatte, Cedex, France; dagger IRSN/DRPH/SDI/Laboratoire d'Evaluation de la Dose Interne, BP17, 92262 Fontenay aux Roses, Cedex, France; double dagger IRSN/DRPH, BP17, 92262 Fontenay aux Roses, Cedex, France.
Data describing the biokinetics of radionuclides after contamination come mainly from experimental acute exposures of laboratory animals and follow-up of incidental exposures of humans. These data were compiled to form reference models that could be used for dose calculation in humans. In case of protracted exposure, the same models are applied, assuming that they are not modified by the duration of exposure. This work aims at testing this hypothesis. It presents new experimental data on retention of uranium after chronic intake, which are compared to values calculated from a biokinetic model that is based on experiments of acute exposure of rats to uranium. Experiments were performed with 56 male Sprague Dawley rats, from which 35 were exposed during their whole adult life to 40 mg L of uranyl nitrate dissolved in mineral water and 21 were kept as controls. Animals were euthanatized at 32, 95, 186, 312, 368, and 570 d after the beginning of contamination. Urine and all tissues were removed, weighted, mineralized, and then analyzed for uranium content by Kinetics Phosphorescence Analysis (KPA) or by ICP-MS. Experimental data showed that uranium accumulated in most organs, following a nonmonotonous pattern. Peaks of activities were observed at 1-3, 10, and 19 mo after the beginning of exposure. Additionally, accumulation was shown to occur in tissues such as teeth and brain that are not usually described as target organs. Comparison with model prediction showed that the accumulation of uranium in target organs after chronic exposure is overestimated by the use of a model designed for acute exposure. These differences indicate that protracted exposure to uranium may induce changes in biokinetic parameters when compared to acute contamination and that calculation of dose resulting from chronic intake of radionuclides may need specific models that are not currently available.
In this third study, acute exposure to depleted uranium (injected intraperitoneally) caused neurotoxic effects. It definitely crossed through the blood-brain barrier.
Toxicology 2005 Sep 1;212(2-3):219-26
The brain is a target organ after acute exposure to depleted uranium.
Lestaevel P, Houpert P, Bussy C, Dhieux B, Gourmelon P, Paquet F.
Institut de Radioprotection et de Surete Nucleaire, Departement de Radio-Protection de l'Homme, Laboratoire de Radio-Toxicologie Experimentale, BP 166, 26702 Pierrelatte, France. [email protected].
The health effects of depleted uranium (DU) are mainly caused by its chemical toxicity. Although the kidneys are the main target organs for uranium toxicity, uranium can also reach the brain. In this paper, the central effects of acute exposure to DU were studied in relation to health parameters and the sleep-wake cycle of adult rats. Animals were injected intraperitoneally with 144+/-10 microg DU kg-1 as nitrate. Three days after injection, the amounts of uranium in the kidneys represented 2.6 microg of DU g-1 of tissue, considered as a sub-nephrotoxic dosage. The central effect of uranium could be seen through a decrease in food intake as early as the first day after exposure and shorter paradoxical sleep 3 days after acute DU exposure (-18% of controls). With a lower dosage of DU (70+/-8 microg DU kg-1), no significant effect was observed on the sleep-wake cycle. The present study intends to illustrate the fact that the brain is a target organ, as are the kidneys, after acute exposure to a moderate dosage of DU. The mechanisms by which uranium causes these early neurophysiological perturbations shall be discussed.
What is the toxic agent, when prions are ashed? (no protein remains)
This information is important, if you know anybody returning from Iraq or even Afganastan, they should be aware of these "new" findings. Supposedly, some of the states are going to test their soldiers for DU upon their return.