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PubMed1990

[Radioactivity of fodder mixtures for poultry and swine].

The investigation was conducted to determine the radioactivities of fodder mixtures and their components for poultry and swine. The total radioactivity, concentrations of potassium, potassium radioisotopes radium and thorium in 273 fodder mixture samples for poultry, 131 fodder mixture samples and concentrates for swine, and 915 component samples of the mixtures were estimated. The radioactivities of fodder mixtures for poultry, swine, and protein concentrates ranged from 212.0 (DKM-2) to 269.0 Bq/kg (DKA-starter), from 206.0 (PT-1) to 233.0 (PP-prestarter), and from 444.0 (KT-1) to 557.0 Bq/kg (Provit), respectively. As to the components of fodder mixture, the radioactivities ranged from 18.0 (fodder phosphate) to 1104.0 Bq/kg (fodder yeasts). The potassium concentrations in fodder mixtures for poultry ranged from 0.82 g/100 g (DKA-starter) to 0.62 g/100 g (KB-1); for swine ranged from 1.97 g/100 g (Provit) to 0.63 g/100 g (PT-1). The highest concentration of potassium was found in fodder yeasts (3.85 g/100 g), and the lowest one in fodder phosphate (0.01 g/100 g). The analysis of the data showed that the radioactivity of the mixtures and their components was mostly conditioned by radiopotassium and revealed correlations between the radioactivities and the total concentrations of potassium. The contamination with the natural radioelements (potassium, radium, thorium) as well as their limited absorption by the gastrointestinal tract, their metabolism in organism, and their radiotoxicological characteristics do not create radiological threat to animals.

Animal Feed↗
PubMed1985

Chemical blockade of the reticuloendothelial system results in arteriolar spasms: possible role of endothelial cells.

Scattered qualitative studies in the literature suggest that the reticuloendothelial system (RES) interacts with the microcirculation to effect host defense and that chemical or pharmacologic blockade of the RES might compromise the microcirculation. With this possibility in mind, we designed experiments in rats to determine whether colloid and pharmacologic blockade of the RES could alter microvascular tone and reactivity. The effects of colloidal carbon, thorium dioxide, tripalmitin and tetracycline on reticuloendothelial system phagocytic function, mesenteric terminal arteriolar tone and arteriolar reactivity to noradrenaline and acetylcholine were examined in situ at magnifications up to 5000x. Colloidal carbon and thorium dioxide, in the doses utilized, produced complete blockade of the RES. Treatment with tripalmitin and tetracycline produced pronounced RES depression. RES blockade and depression were associated with marked reductions in terminal arteriolar lumen sizes, curtailment of capillary inflow and outflow, hyper-reactivity to the constrictor, noradrenaline, and hypo-reactivity to the dilator, acetylcholine. Close examination of the endothelial linings of the capillaries, postcapillary venules and terminal arterioles of the experimentally-treated animals indicated pronounced uptake of carbon particles in the endothelial cells, different degrees of endothelial cell swelling and often bulging into the microvessel lumens. Our findings suggest that RES-induced alterations in microvascular tone and arteriolar reactivity may be related to injury of the microvascular endothelial cells.

Animals↗
PubMed1984

[Late complication of angiography - thorotrastoma causing pharyngeal phlegmon].

Carotid angiography with the use of thorium dioxide for brain tumour diagnosis has been performed in a woman 35 years ago. In the course of angiography thorium dioxide penetrated into the paravascular space with subsequent development of "thorothrustoma" the clinical symptoms of which progressed for years (compression of neck organs and nerves, gradual disturbance of swallowing). As a result of compression a decubitus ulcer and phlegmona of the pharyngeal wall developed. Late diagnosis of the phlegmona and its inadequate treatment resulted in aspiration pneumonia which was a direct cause of the patients death.

Aged↗
PubMed1994

Radiation-induced systemic and local bone tumors: two types of late effects with possible different origins?

Bone sarcomas may be induced throughout the skeleton (systemic) in mice by relatively low internal alpha-particle doses that are distributed over the whole skeleton. The induction of local (periosteal) bone sarcomas after paratibial deposition of insoluble radiocolloids required much higher doses, and in addition high energies of emitted particles. Paratibial deposition of alpha-particle-emitting radiocolloids of 227Th and 228Th resulted in formation of both local and systemic bone sarcomas. The latter were most probably induced by the released radium daughters of the thorium isotopes and were distributed about the skeleton. Paratibial injections with beta-particle emitters 144Ce+ 144Pr (29 kBq per mouse) showed an incidence of local bone sarcomas of more than 80%. An estimation of the local effective doses led to values of more than 1000 Gy for the beta-particle emitter 144Ce and around 150 Gy for the thorium isotopes. Thus induction of local bone sarcomas required doses considerably greater than those needed for systemic bone sarcomas. The local induction of bone sarcomas has been reported for high-energy beta particles using similar high doses of 144Ce+ 144Pr in rats and for external 90Sr+ 90Y irradiation in mice. We conclude that the processes involved in the induction of local and systemic bone sarcomas by radiation may be quite different.

Animals↗
PubMed2004

Preliminary results on the immobilisation of radionuclides from waters with specific adsorbers based on phosphate salts.

The present paper is focused on the ability of aluminium phosphate (ALPC), magnesium ammonium phosphate (MGPC), magnesium hydrogen phosphate (MGHPC), and calcium hydrogenphosphate (CAHPC), adsorbed onto charcoal, to immobilise actinides by adsorption from natural waters. The objective of this process is to evaluate the environmental pollution due to the actinides. Europium, thorium, protactinium, neptunyl, and uranyl ions were chosen to simulate actinides in the +3, +4, +5 and +6 oxidation state. The adsorbers were tested using natural waters samples. The adsorption trends and capacities were analysed. ALPC and MGPC exhibited a similar behaviour and adsorbed demonstrating that the +5, +4 and +3 actinide ions can be easily immobilised from natural waters and may be successfully used at pH 7-8. MGHPC may be used at a higher pH, whereas CAHPC is effective in the whole pH range. In all cases, thorium, protactinium and europium were strongly

Actinoid Series Elements↗
PubMed1982

Inhibition of vacuolar membrane fusion by intracellular symbiotic algae in Hydra viridis (Florida strain).

Hydra viridis (Florida strain) forms a stable symbiotic association with unicellular Chlorella-like algae. Algae are phagocytized by hydra phagocytes and maintained individually within vacuoles of the host-cell. The purpose of the studies presented in this paper was to determine how symbiotic algae avoid host-cell digestive processes. Viable symbiotic algae were found to inhibit the fusion of the algal vacuolar membrane and vacuoles labeled with thorium dioxide. By contrast, thorium-labeled vacuoles did fuse with vacuoles containing nonviable algae. Further, the absence of acid phosphatase activity within vacuoles containing established symbiotic algae implies that inhibition of membrane fusion by algae in hydras prevents the conversion of the algal vacuoles into phagolysosomes.

Acid Phosphatase↗
PubMed1976

Heterotopic allotransplantation of isolated aortic cells. An electron microscopic study.

Smooth muscle cells were enzymatically isolated from the tunica media of the aorta of 5-day-old rats. Following in vitro exposure to colloidal thorium dioxide particles the cells displayed numerous lysosomes filled with these particles. Intramuscular injection of isolated cells into the tongues of young rats of the same strain, resulted in the formation by both freshly isolated and thorium dioxide-labeled cells of a characteristic tissue similar to that found in the intact aortic wall. Thus, the transplants consisted of typical smooth muscle cells surrounded by an extracellular matrix consisting of a microfibrillar network, patches and fibers of elastin, collagen fibrils and small polygonal granules believed to represent proteoglycans. This system can be used for experimental studies on the production of extracellular matrix components and on other functions of arterial smooth muscle cells growing outside the vascular wall.

Animals↗
PubMed2005

The Hiroshima thermal-neutron discrepancy for (36)Cl at large distances. Part I: New (36)Cl measurements in granite samples exposed to A-bomb neutrons.

The long-lived radioisotope (36)Cl (half-life: 301,000 years) was measured in granite samples exposed to A-bomb neutrons at distances from 94 to 1,591 m from the hypocenter in Hiroshima, by means of accelerator mass spectrometry (AMS). Measured (36)Cl/Cl ratios decrease from 1.6 x 10(-10) close to the hypocenter to about 1-2 x 10(-13), at a distance of 1,300 m from the hypocenter. At this distance and beyond the measured (36)Cl/Cl ratios do not change significantly and scatter around values of 1-2 x 10(-13). These findings suggest that the (36)Cl had been predominantly produced by thermalized neutrons from the A-bomb via neutron capture on stable (35)Cl, at distances from the hypocenter smaller than about 1,200 m. At larger distances, however, confounding processes induced by cosmic rays or neutrons from the decay of uranium and thorium become important. This hypothesis is theoretically and experimentally supported in a consecutive paper. The results are compared to calculations that are based on the most recent dosimetry system DS02. Close to the hypocenter, measured (36)Cl/Cl ratios are lower than those calculated, while they are significantly higher at large distances from the hypocenter. If the contribution of the cosmic rays and of the neutrons from the decay of uranium and thorium in the sample was subtracted, however, no significant deviation from the DS02 calculations was observed, at those distances. Thus, the Hiroshima neutron discrepancy reported in the literature for (36)Cl for samples from large distances from the hypocenter, i.e., higher measured (36)Cl/Cl ratios than predicted by the previous dosimetry system DS86, was not confirmed.

Biophysical Phenomena↗
PubMed2005

Elemental composition of Jamaican foods 1: a survey of five food crop categories.

The concentrations of 27 elements in Jamaican food categories consisting of fruit, legumes, leafy and root vegetables and other root crops are reported. The main analytical techniques used were neutron activation analysis and flame and graphite furnace atomic absorption spectrophotometry. The results are compared, where possible, with values from Denmark, the United Kingdom, the United States and Nigeria, and with some regulatory limits. Over 75% of the results for antimony, arsenic, barium, cerium, thorium and uranium were below the respective sample detection limits but even among these, some of the maximum values observed indicate that further examination may be useful for those foods grown in the regions of highest uptake and consumed in large amounts. The other elements reported are bromine, cadmium, calcium, caesium, cerium, chromium, copper, europium, hafnium, iron, lanthanum, lead, magnesium, manganese, phosphorus, potassium, rubidium, scandium, samarium, sodium, strontium, thorium, uranium, and zinc. Many of these elements occur at concentration levels above those reported from the other countries but it seems unlikely that most of these will contribute significantly to public health risk. However, at this stage cadmium clearly appears to be the element of greatest concern in the Jamaican food chain. The observed range of cadmium concentrations suggests that factors such as land selection, coupled perhaps where necessary, with suitably modified agricultural practices, is a feasible way to reduce the cadmium content of certain local foods.

Animals↗
PubMed1982

Long-term occupational risk of rare-earth pneumoconiosis. A case report as investigated by neutron activation analysis.

A case of rare-earth (RE) pneumoconiosis is described and discussed. A man working in a lithographic laboratory as a photoengraver, and exposed to the smoke of cored carbon arc lamps over a period of 46 years developed an interstitial pneumoconiosis. Neutron activation analysis (NAA) of eight rare-earths (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in lung and lymph node biopsies showed an abnormally high amount of these elements in comparison to the corresponding values of 11 autopsied for unexposed subjects. The estimated radiological dose due to the inhalation of natural thorium, as calculated from NAA of thorium in the biopsies, tends to exclude the effect of ionizing radiation in the pathogenesis of lung fibrosis. Effects of other potential pathogenetic agents such as coal or heavy metal dusts, other than RE, irritative agents such as nitrous and hydrofluoric vapours originated during the photoengraving process, are also discussed. The findings strongly suggest that a relationship exists between the pneumoconiosis diagnosed and the occupational exposure to rare-earth dusts calling attention to proposals for maximum permissible concentration limits of occupational exposure to RE in air.

Animals↗
PubMed1987

Liver tumors in rodents: extrapolation to man.

Man is a poor model for the prediction of agents that are hepatocarcinogenic for laboratory rodents. Relatively few agents are known to cause any form of primary liver cancer in man. The most important is hepatitis B virus, for which there is possibly a model in the woodchuck but not one in rats or mice. The only other agents known to cause primary liver cancer in man are certain steroid hormones, vinyl chloride, and thorium dioxide. There are animal models for the first two of these and a reasonable expectation that thorium dioxide would produce liver tumors in animals if the appropriate experiments were done. Aflatoxin, a potent hepatocarcinogen in rats and other species but not mice, is strongly suspected of being an important human hepatocarcinogen in certain geographical areas of the world, but the evidence is circumstantial. There is no more than a weak association between the nutritional type of cirrhosis secondary to excessive intake of alcohol and increased primary liver cancer in man, and no evidence at all that ethanol per se causes liver tumors in mice, rats, hamsters, or mastomys. By contrast, a very large number of chemicals to which people in the West have been exposed for many decades have been found to be hepatocarcinogens in laboratory rodents. In most cases the levels of exposure required to produce liver tumors in rodents far exceed those to which man is normally exposed. The problem is to guess whether low-level exposure to such rodent hepatocarcinogens poses any real liver cancer threat to man?The mortality from primary liver cancer is very low in countries such as England and Wales where there is widespread exposure to low doses of both natural and synthetic agents which, in high dosage, cause liver tumors in rodents. This suggests that, if there is any risk, it can only be very small. Death rate data collected in England and Wales by the Registrar General are consistent with there having been a small increase in the incidence of primary liver cancer in England and Wales during the past 20 years, but the apparent increase might well be a consequence of revisions in the International Classification of Diseases system and not real. During the first half of the present century the age-standardized incidence of primary liver cancer in England and Wales was falling.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Splenic angiosarcoma following chemotherapy for follicular lymphoma.

A case of splenic angiosarcoma in a patient who had been treated for a follicular lymphoma with chemotherapy over a period of about nine years is reported. The etiologic agents for angiosarcomas at various sites, and their associations with other tumors, are reviewed. The most important of these associations are radiotherapy and lymphedema with tumors of the skin and soft tissues; and vinyl chloride, arsenic, and thorium dioxide with hepatic tumors. For splenic angiosarcomas, only isolated associations with breast carcinoma and thorium dioxide exposure have been reported. In the present case long-term combination chemotherapy seems to be the most likely etiologic association.

Adult↗
PubMed2002

Transfer of selected elements from food into human milk.

OBJECTIVES: We measured the transfer factors of antimony, cerium, chromium, cobalt, gallium, lanthanum, molybdenum, niobium, ruthenium, silver, thorium, titanium, and uranium from food to milk in nursing mothers. METHODS: Food and milk samples from 19 mothers were taken daily over 2 to 8 wk. The samples were analyzed for element content after microwave-assisted pressure digestion with a mass spectrometer and inductively coupled plasma. The transfer factor, or the portion of element intake passed on in the milk, was calculated as the element concentration in food (g/kg) divided by the element concentration in milk (g/L). RESULTS: The calculated transfer factors were 5.1 for silver, 16.1 for cerium, 6.9 for chromium, 8.4 for cobalt, 19.1 for gallium, 13.8 for lanthanum, 77.4 for molybdenum, 20.7 for niobium, 4.1 for ruthenium, 13.2 for antimony, 20.2 for thorium, 5.6 for titanium, and 21.3 for uranium. Factors differed significantly across individuals. CONCLUSION: These differences can be attributed to the fact that the different levels of elements in breast milk are the result of individual differences in milk production and factors other than the amount of any particular element absorbed by the body.

Adult↗
PubMed2000

Practical applicability of field gamma-ray scintillation spectrometry in geophysical surveys

We discuss the problems and calibration procedures for a portable gamma-ray scintillation spectrometer for determinations of potassium, uranium and thorium concentration in rocks. Particular emphasis was given to the evaluation of the background radiation. The apparatus was tested in the field at two selected areas in NW Italy. We found appropriate sites which could be used as reference targets to frequently check the gamma-ray equipment. An area formed by serpentinitic rocks showed such a low measured radioactivity that it could be used as a reference for the local background effect. An anomalously high uranium amount against negligible potassium and thorium concentrations were found in outcrops of dolomitic rocks, which can be used to detect possible changes in the instrument calibration constants.

Journal Article↗
PubMed2001

Preparation of alpha-sources of U(VI) and Th(IV) by the electrodeposition technique in the presence of Ca2+ and some trivalent metals.

A new method for the electrodeposition of uranium and thorium from an aqueous/ethanol media in the presence of Ca(II) and some trivalent metals is described. The deposition is carried out at a constant weak voltage of 30 V and starting current intensity of 3 A. The deposition yields of uranium is investigated as a function of the amounts of various carriers and impurities such as Fe, Al, Bi, La and Ca as well as acetic, nitric and hydrochloric acids. All solutions containing up to 900 ppm of Ca2+ and 100-150 microg of the foreign ions namely: Fe, Bi or La can be used with no chemical separation. Uranium and thorium recoveries between 80 and 96% are obtained and the resolution is typically 25-40 keV. Procedure without chemical purification is proposed for a selective electrodeposition of U(VI) and Th(IV) from one another and from calcium.

Journal Article↗
PubMed2002

A method for preparation and purification of 234Th.

An improved method to recover 234Th from depleted uranium has been developed. The method is based on solvent extraction and ion-exchange separations. The final thorium fraction has a high specific activity, about 1-3 PBq/mol Th, which makes it well suited for investigations, where a low thorium concentration is essential. The method is comparably fast, with a total processing time of 2 days. Another advantage is that the uranium fraction can be used as a 234Th generator for several years.

Journal Article↗
PubMed2006

Preparation and optical properties of ThO(2) and Eu-doped ThO(2) nanotubes by the sol-gel method combined with porous anodic aluminum oxide template.

In this paper, we report the synthesis of thorium oxide and Eu-doped thorium oxide nanotubes for the first time using the sol-gel method in porous anodic aluminum oxide template. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were applied to characterize the morphology and structure of the as-prepared nanotubes. It has been demonstrated that Eu(3+) ions were homogeneously doped into the ThO(2) crystal lattice. The optical properties resulting from Eu-doped products were investigated by means of photoluminescence spectroscopy. Strong visible light emissions were observed at low doping concentration, and the luminescent intensity decreased at high doping concentration. The luminescent centers were concluded to be the Eu(3+) ions in the cubic (O(h)) sites rather than the C(3v) sites, which accounted well for the decrease of luminescent intensity at high doping concentration.

Journal Article↗
PubMed2005

Helium solubility in olivine and implications for high 3He/4He in ocean island basalts.

High 3He/4He ratios found in ocean island basalts are the main evidence for the existence of an undegassed mantle reservoir. However, models of helium isotope evolution depend critically on the chemical behaviour of helium during mantle melting. It is generally assumed that helium is strongly enriched in mantle melts relative to uranium and thorium, yet estimates of helium partitioning in mantle minerals have produced conflicting results. Here we present experimental measurements of helium solubility in olivine at atmospheric pressure. Natural and synthetic olivines were equilibrated with a 50% helium atmosphere and analysed by crushing in vacuo followed by melting, and yield a minimum olivine-melt partition coefficient of 0.0025 +/- 0.0005 (s.d.) and a maximum of 0.0060 +/- 0.0007 (s.d.). The results indicate that helium might be more compatible than uranium and thorium during mantle melting and that high 3He/4He ratios can be preserved in depleted residues of melting. A depleted source for high 3He/4He ocean island basalts would resolve the apparent discrepancy in the relative helium concentrations of ocean island and mid-ocean-ridge basalts.

Journal Article↗