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Special Problems of Internal Radioactive Materials
Published in George W. Casarett, Radiation Histopathology, 2019
Thorium-232 is an alpha emitter with a physical half-life of 1.39 × 1010 years. After its introduction in 1928, thorotrast, a 20% colloidal suspension of thorium dioxide, became widely used as a contrast medium in diagnostic radiology. Amounts of 3 to 15 grams were administered intravenously. The colloidal particles are rapidly phagocytosed and concentrated in cells of the reticuloendothelial system. Looney76 found that the excretion of thorium dioxide is minimal. He estimated the biological half-life to be about 190 years. The colloid tends to remain fixed in the tissues, although there is some migration which is probably accomplished within the macrophages which are migrating.
Assembly of a Technological Vision for X-Ray Contrast Agents
Published in Christoph de Haën, X-Ray Contrast Agent Technology, 2019
Around 1927, Theophil Blühbaum (alias for Czesław Murczyński) (Leszczyński 2000b), a radiologist postdoctoral fellow from Krakow, working with Karl Frik, the chief of the Werner Siemens-Institute for Röntgen Research at the Municipal Hospital Moabit in Berlin (Casper 1967) and his radiologist associate, Helmut Kalkbrenner, engaged in a search for improved contrast agents, returning to colloidal preparations. They discovered the clinical utility of plain colloidal thorium dioxide, a radioactive substance erroneously considered harmless, as contrast agent for the liver and the spleen (Blühbaum, Frik, and Kalkbrenner 1928). Siemens-Reiniger-Veifa Gesellschaft für Mediziniche Technik m. b. H, Berlin) and Chemische Fabrik von Heyden AG, Dresden, Germany, put the same colloidal thorium dioxide on the market, under the respective trade names TORDIOL™ and UMBRATHOR™.31 Through the addition of protection colloid, the latter company achieved a product with improved stability in the blood, generically called stabilized colloidal thorium dioxide (THOROTRAST™). This product and its congeners allowed the acquisition of angiographic images of unsurpassable sharpness and resolution of various anatomical territories, the brain included but left a tragic legacy in the form of permanent deposition of the radioactive contrast agent in the liver, where in some cases, it produced tumors (Andersson, Juel, and Storm 1993).
Other causes of mesothelioma not related to asbestiform mineral fibers
Published in Dorsett D. Smith, The Health Effects of Asbestos, 2015
The relationship between cumulative external radiation dose and the proximal mortality ratio (PMR) for mesothelioma, suggests that external radiation at nuclear facilities is associated with an increased risk of mesothelioma. (Gibb H, Fulcher K, Nagarajan S et al. Analyses of radiation and mesothelioma in the US transuranium and uranium registries. Am J Public Health 2013;103(4):710–6.) Thorium dioxide has been implicated as a cause of mesothelioma. (Maurer R, Egloff B. Malignant peritoneal mesothelioma after cholangiography with thorotrast. Cancer 1975;36(4):1381–5.)
Mesothelioma mortality within two radiation monitored occupational cohorts
Published in International Journal of Radiation Biology, 2022
Michael T. Mumma, Jennifer L. Sirko, John D. Boice, William J. Blot
Radiation. Therapeutic doses of radiation and injection with Thorotrast, an alpha-particle emitting colloidal solution of thorium dioxide used as a diagnostic radiographic contrast medium, are likely causes of mesothelioma, including cancers of the pleura and peritoneum. However, cancer of the pleura is not increased among atomic bomb survivors, and large-scale studies of occupational groups exposed to low radiation levels are either negative or the increases are attributed to asbestos exposure. Associations between radiation and asbestosis (which is only caused by asbestos) indicate that jobs with relatively high radiation exposures are highly correlated with jobs with relatively high asbestos exposure. Over 83,000 IRs not employed at shipyards did not have an excess of mesothelioma or asbestosis, and there was no clear evidence of a radiation dose-response relationship in the overall cohort. Low-dose radiation received in these occupational setting was not found to be associated with mesothelioma.
Structure and function of the open canalicular system – the platelet’s specialized internal membrane network
Published in Platelets, 2018
Maria V. Selvadurai, Justin R. Hamilton
A major function of the OCS is the transport of substances into and out of the platelet. Platelets have very little capacity for protein synthesis, so much of their cargo is taken up from plasma sources. This uptake largely occurs via the OCS, with a number of plasma proteins including fibrinogen (32) and tissue factor (33) taken up through channels of the OCS and then subsequently distributed to organelles within the platelet (e.g. alpha or dense granules). Behnke’s early studies showed that particles added to platelet-rich plasma in vitro, or infused intravenously in vivo, were subsequently found in channels of the OCS, without any change in platelet morphology (1). White soon confirmed this finding and showed that thorium dioxide particles added to platelet-rich plasma were observed not only in OCS channels, but also in alpha granules – even when these granules had no visible physical association with the OCS (2). These early studies by the two pioneering researchers of OCS confirmed the ‘open’ nature of the OCS and revealed that these internal platelet channels are essentially exposed to the same medium as the platelet exterior.