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At least 19 recordsLinked to original sources
PubMed1990

Ion exchange chromatography on a new form of tin dioxide for the isolation of strontium radioisotopes from fission products: an application to milk samples.

An amorphous, partially-reduced tin dioxide, having properties of an inorganic exchanger, was tested for application to fission product separations. Due to the good sorption of both strontium and barium the application of the exchanger to radiostrontium isolation from fission product mixtures is subject to important restrictions. An application to 90Sr determination in milk is proposed.

Animals↗
PubMed1975

Influence of perfusion pressure and heart rate on local myocardial flow in the collateralized heart with chronic coronary occlusion.

We studied the influence of controlled changes in perfusion pressure and heart rate on the regional distribution of myocardial flow in normal dogs and in dogs with multiple chronic coronary artery occlusions but without infarctions. Local myocardial blood flow was determined with the tracer microsphere technique. By stepwise altering of systemic blood pressure during maximal vasodilation classical pressure flow relations were obtained. One week after complete chronic occlusion a functionally and anatomically well-defined compartmentation of blood flow was found. The dilatory reserve is clearly compromised not only in the collateral-dependent myocardium but also in the apparently normal myocardium which delivers collateral flow. An "arterio-arterial shunting" mechanism is shown to exist. Several months after coronary occlusion, regional mycoardial flow is still nonhomogeneous. Although the coronary dilatory capacity of the collateralized myocardium is nearly normal, that of the normal myocardium is found to be higher than normal. Vessel growth in both areas is discussed as being responsible for this phenomenon. Right ventricular pacing during maximal vasodilation produces a flow decrease to the endocardial muscle layers in normal dogs, while the epicardial flow is unchanged. One week after complete chronic coronary occlusion pacing during maximal vasocilation reduces the dilatory capacity in the collateralized areas to such an extent that the supplementary increase in myocardial oxygen demand will induce ischemia because of the compromised oxygen supply.

Animals↗
PubMed1979

Radioisotope therapy in bone and joint disease.

The short range tissue destruction of beta-emitting radioisotopes can be utilized in painful metastatic disease of the skeleton by employing a radionuclide that is specifically metabolized in or adjacent to these lesions. Sodium phosphate P 32 has been used for this purpose for the past 25 yr. It uptake in skeletal tumor and in osteoblastic new bone adjacent to tumor can be markedly increased by pharmacologic stimulation using androgenic steroids, or during rebound deposition after a course of parathyroid hormone. Although efficacy in terms of subjective pain relief is high, more objective signs of success are often lacking, and survival, while more confortable, is not prolonged. Marrow depression is the most significant side effect. A beta-emitting, bone-seeking isotope, 89Sr, may have a better therapeutic/toxic ratio, and should receive further trial. Radiation-induced necrosis has also been applied, though more hesitantly, to the proliferative, destructive, but nonmalignant synovium in rheumatoid disease. Here, a number of colloidal preparations, most commonly 198Au, have been employed. Again, relief of symptoms, particularly recurrent joint effusions, is quite high, although the basic disease process is not reversed. The major hazard here appears to be leakage of material to regional lymph nodes, resulting in irradiation of circulating lymphocytes. Although chromosomal damage can be detected when such cells are then cultured, the actual consequences of this, if any, are not presently known. Both shorter-lived (165Dy) and longer-lived (32P) larger-size colloids are being evaluated, which may prove safer in this regard than 198Au.

Bone Marrow↗
PubMed1976

The dosimetry of radioisotopes incorporated in bone using cavity ionization theory.

Cavity ionization theory is applied to the dosimetry of bones incorporating beta- and gamma-emitting radioactive isotopes. The assumptions inherent in different theoretical approaches to bone dosimetry are reviewed and compared with those adopted in cavity theory. In presenting the theory attention is given to the effects of electron and photon attenuation and to the absence of electronic equilibrium which may occur in bone. The mean marrow dose is calculated for a range of cavity size and gamma-ray energies and for a beta-ray emitter. The mean marrow dose and the mean endosteal dose are calculated for a human lumbar vertebra and some comparisons made with the results of other workers. It is concluded that cavity theory provides a useful approach to the dosimetry problems of bone-seeking beta- and gamma-ray radioactive isotopes.

Adult↗
PubMed1976

Calculated beta-ray dose factors for trabecular bone.

Mean dose factors have been calculated for those tissues in bone that are relevant to the induction of late irradiation effects; namely, red bone marrow and endosteal tissues lining trabecular bone surfaces. The calculations are based on a Monte Carlo computer method for beta-emitting radionuclides which are distributed uniformly throughout the volume of mineralized bone. Results are given for the radionuclides 14C, 45Ca, 22Na, 18F, 32P, 90Y and 90Sr+90Y (all considered for this purpose as volume-seekers) for seven bones from the adult human skeleton and calculations are also presented of average skeletal dose factors. Where possible, results are compared with those derived from other methods based on simple geometrical models.

Adult↗
PubMed1977

[Correlation between gastrointestinal absorption and uptake of radioisotopes by the critical organs].

This study was undertaken to investigate the correlation between gastrointestinal absorption of radioisotopes and uptake by the critical organ during the same period using 85Sr, 109Cd, 131I and 203Hg as radioisotopes. When the distribution of 85Sr, 109Cd, 131I and 203Hg in mice were investigated by means of the whole body autoradiography, these critical organs were determined as follows; 85Sr: bone, 109Cd: liver, 131I: thyroid gland and 230Hg: kidney. When the correlation between the injected dose and the uptake dose by the critical organ of 85Sr, 109Cd, 131I and 203Hg were investigated, uptake dose the critical organ expressed as cpm per gram of organ was in direct proportion to the injected dose and that expressed as % of the injected dose per gram of organ was held constand in either case. When the coefficient of correlation between gastrointestinal absorption and uptake by the critical organ of 85Sr, 109Cd, 131I and 203Hg were calculated, a positive correlation was revealed in either case. It is concluded from the results obtained that in vivo or in situ method, gastrointestinal absorption of radioisotopes received a support from uptake by the critical organ during the same period.

Animals↗
PubMedDate not supplied

[Absorption of radiocobalt in Chlorella vulgaris]?1Assorbimento di radiocobalto in "Chlorella vulgaris".

The uptake, accumulation and loss of traces of radiocobalt present in the culture medium by a green alga, Chlorella vulgaris, were studied. The trace quantities of the radionuclide employed had no effect on the growth of the algal population. The uptake is related to the number of cells present and to the temperature of the culture medium; it is not affected by mitotic activity. The rate of the 60Co, uptake during algal growth is compared to the rate of uptake of other radioisotopes; 90Sr and, to some extent, 137Cs have the same rate of uptake as 60Co, whereas 90Y and 144Ce differ. Perhaps the radiocobalt in the cells undergoes a chelating process and consequently its loss to the outer environment is very slow. The involvement of a biological process, in addition to a physical one, is claimed in order to explain the possibility of an active concentration of the radioisotope (C.F.=170). Emphasis is laid on the possible danger of this concentration when a disposal system by dilution of industrial or nuclear waste is employed.

Cesium Radioisotopes↗
PubMed1979

The use of 22Na as a tracer for long-term bone mineral turnover studies.

Sodium-22 has been studied as a tracer for bone mineral metabolism in rats and dogs. When incorporated into bone during growth from birth to adulthood, the bone becomes uniformly tagged with 22Na, which is released through the metabolic turnover of the bone. The 22Na not incorporated in the bone matrix is rapidly excreted within a few days when animals are fed high, but nontoxic levels of NaCl. The 22Na tracer can be used to measure bone mineral loss in animals during space flight and in research on bone disease.

Adult↗
PubMed1975

Occurrence of hemangiosarcomas in beagles with internally deposited radionuclides.

In a series of related experiments to evaluate the relative toxicity of inhaled radionuclides, beagles were exposed to aerosols containing relatively soluble (chloride) or relatively insoluble (fused clay) forms of 144-Ce and 90Sr. With the solubled 144-CeCl3, significant radiation doses were delivered to the lungs, liver, and skeleton whereas, after 90-SrCl2 exposure, the radiation dose was delivered predominantly to the skeleton. In dogs exposed to 144-Ce and 90-Sr in fused clay particles, radiation doses were delivered mostly to the lungs and tracheobronchial lymph nodes. In most dogs dying within 2 years after exposure, deaths were attributable to nonneoplastic radiation-induced lesions in the target organ systems. At later times after exposure, neoplasms were the major cause of death, again occurring mostly in target organs or the adjacent tissues. Lung liver, and bone-related neoplasms, including five hepatic hemangiosarcomas, developed after 144-CeCl3 exposure. Among the bone-related sarcomas seen in dogs exposed to 144-CeC3 or 90-SrC2, the incidence of hemangiosarcomas was over 40%. Among the 20 dogs dying with pulmonary neoplasms after exposure to 144-Ce or 90Sr in fused clay particles, all had hemangiosarcomas and several also had other neoplasms. This high after exposure and differs from results in other laboratories where beagles have been exposed to both alpha and beta-emitting radionuclides.

Aerosols↗
PubMedDate not supplied

[Radionuclide transfer by migratory birds].

Evaluation of the zoogenic transfer of radionuclides from the 30-km zone around the Chernobyl NPP was necessary because of the enormous heavily polluted territory and mighty flow of migratory birds who tended to large rivers, the Dnieper and Pripyat. The integral estimate of the transferred amount was obtained as a product of three variables: the transfer factor (0.0077 m2/kg for 137Cs; 0.0107 m2/kg for 90Sr), the density of birds (0.002 kg/m2, at the mass of migrants about 5000 t per year), and the total fund of radionuclides throughout the territory. The upper estimated limit of the annual transfer rate was 5.5 Ci (2E + 11 Bq) for 137 Cs and 1.8 Ci (6.7E + 10 Bq) for 90 Sr. Restrictions of hunting are recommended within the northern part of the Kiev reservoir.

Accidents↗