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At least 19 recordsLinked to original sources
PubMed1988

Effect of microbial biomass reduction by gamma-irradiation on the sorption of 137Cs, 85Sr, 139Ce, 57Co, 109Cd, 65Zn, 103Ru, 95mTc, I by soils.

Six soils, two Sphagnum peat samples and a clay mineral were irradiated with 40 and 80 kGy (4 and 8 Mrad) from a 60Co source. As a result the microbial biomass, determined separately for each sample, decreased considerably. Depending on the radionuclide, the sorption, as characterised by the distribution coefficient, decreased, increased or remained unchanged. The effect of the irradiation on the sorption of the radionuclides depended, in general, also on the type of the sample, especially whether well humified soils, (e.g. crop soils), poorly humified samples (Sphagnum peat, O-horizon from woodland), or a clay mineral was employed. The data reveal that irradiation produces, besides sterilization, also other effects in soils, which can change their sorption properties.

Adsorption↗
PubMedDate not supplied

Regional cerebral blood flow in the rat as determined by particle distribution and by diffusible tracer.

Measurements of total and regional cerebral blood flow in paralyzed rats maintained on 70% N2O/30% O2 obtained by a diffusible tracer technique, iodoantipyrine, and by a particle distribution method, microspheres, have been compared. Total CBF values were in good agreement, 0.86 +/- 0.07 ml/g/min (PaCO2 37.3 +/- 1.5, iodoantipyrine method) and 0.88 +/- 0.02 (PaCO2 36.2 +/- 0.8, microsphere method). Regional cerebral blood flows showed good agreement with the 2 methods, with highest flow in the colliculi, striatum and cerebral cortex and lowest flows in the hypothalamus, pons medulla and cerebellum. The iodoantipyrine method is technically easier to perform and had a higher precision.

Animals↗
PubMedDate not supplied

Gut retention of metals in rats.

In sucklings, a high fraction of orally administered metals and radionuclides is retained in the gut. The location of elements in the gut is of interest because of their potential local health effect. The purpose of this work was to evaluate the influence of chelation therapy on gut retention and location of cadmium, mercury, and cerium in suckling rats. Radionuclides 115mCd, 203Hg, and 141Ce were administered orally to 6-d-old rats. Chelating agent Zn-DTPA (3.64 mmol/kg) was administered to animals that received 115mCd or 141Ce and Na-DMPS (375 mumols/kg) to those that received 203Hg, immediately and 24 h or 24 and 48 h after radionuclide administration. Radioactivity was determined in the whole body and gastrointestinal tract 6 d later. Both early and delayed chelation treatment very effectively reduced whole body retention, and this was mainly owing to reduced gut retention. Although chelation therapy reduced gut retention of administered radionuclides 3-30 times, the site of metal accumulation and retention in the intestine remained unchanged. For all 3 radionuclides, both after early and delayed therapy, the site of metal accumulation was always the lower part of small intestine-ileum.

Animals↗
PubMed1987

[Decontamination effectiveness of Ca-, Zn- and MnDTPA chelates in internal contamination with Cs-137, Ce-144, J-131, Sr-90 radioisotopes].

The studies were carried out on 240 rabbits divided into 4 groups, in which, after contamination with i.v. radioisotopes 137Cs (A), 144Ce (B), 131J (C), 90Sr (D), Ca-, Zn-, MnDTPA chelates were used in 12.5% water solutions in doses of 0.4 g/kg of body weight. The evaluation of the decontaminating effectiveness of the above DTPA compounds, taking into account veterinary-clinical and veterinary-sanitary aspects, was made with to the individual radioisotopes on the basis of radiometric studies. These studies carried out after 1,2,4,6,15 days from the contamination, by using a measurement system, concerned the following organs and tissues: blood, brain, heart, muscles of the thigh and arm, lungs, kidneys, liver, stomach, colon, bone, thyroid gland. The results expressing the per cent values of radioactivity of the organs in relation to the dose of the radioisotopes introduced into the organism and to the value of radioactivity of the particular organs in Bq/100 mg of ash, including discussion and conclusions, are presented in individual groups. From these data it can be assumed for practical veterinary purpose that Ca-, Zn-, MnDTPA chelates show an effective action with respect to the veterinary-clinical aspect in contamination with radiocerium, and with respect to the veterinary-sanitary aspect in contamination with radiocerium and radioiiodine; less effective action with respect to the veterinary-sanitary aspect, and ineffective with respect to the veterinary-clinical aspect in contamination with radiocesium; negative one with respect to both aspects in contamination with radiostrontium. As regards the individual chelating compounds, the most effective can be recognized sodium zinc salt of DTPA.

Animals↗
PubMed1994

Influence of dearterialization on distribution of absolute tumor blood flow between hepatic artery and portal vein.

BACKGROUND: Conflicting results have been obtained regarding blood flow distribution to liver tumors. The emphasis on portal vein perfusion has had a great impact on the design of treatment protocols. METHODS: Double microsphere technique with reference organ sampling was used for the measurement of hepatic artery and portal vein blood flow of an implanted liver tumor in 42 rats after permanent dearterialization and repeated dearterialization (2 hours/day) compared with untreated sham-operated controls. RESULTS: Portal venous blood flow constituted 16% of total tumor blood flow and slightly increased after permanent and repeat dearterializations, though the elevation was not statistically significant as compared with sham-treatment (P > 0.05). In another 3 groups, the treatment was extended to 10 days, and tumor blood flow was measured in central and peripheral parts separately. Arterial blood flow further decreased in tumor periphery and was still lower in the tumor center (P < 0.01 versus tumor periphery), and portal blood flow declined concomitantly to 4% of total tumor blood perfusion. However, no difference in portal blood flow between the tumor center and periphery could be demonstrated (P > 0.05). Furthermore, portal supply increased neither in tumor periphery nor in tumor center after both permanent and repeated dearterialization (P > 0.05). CONCLUSION: The authors' results showed that portal blood flow did contribute to tumor circulation, but made up only 16% of blood flow when tumors were small and declined to 4% of entire tumor blood supply when tumors became large. Portal perfusion also declined as tumors grew larger and did not compensate for the withdrawal of tumor arterial blood supply after dearterialization.

Animals↗
PubMed1977

Studies of bone and soft-tissue tumours induced in rats with radioactive cerium chloride.

A colloidal suspension of radioactive cerium chloride was inoculated into the hind legs of Sprague Dawley rats. Bone and soft-tissue tumours were induced at the site of inoculation in 77% of the animals. All bone tumours were osteogenic osteosarcomas. Soft tissue tumours were mostly malignant and were of various histological types, predominantly fibrosarcomas, haemangiopericytomas, angiosarcomas and rhabdomyosarcomas. A kinetic study showed that the doubling time (DT) of tumours was closely correlated with the anatomical site of tumour development: bone tumours had a DT of 17.4 +/- 4.3 days and malignant tumours which developed in soft tissues had a DT ranging from 7.4 to 8.4 days with the exception of two haemangiosarcomas which had a long DT of 17 +/- 0.6 days. Pulmonary metastases were frequent for osteosarcomas and tumours of vascular origin. This model of induction of bone and soft-tissue tumours in rats by injection of a colloidal suspension of radioactive cerium chloride offers the possibility of more comprehensive physiopathological and kinetic studies of these tumours and may constitute a good model for their human counterparts.

Animals↗
PubMed1980

Malignant bone tumours induced by a local injection of colloidal radioactive 144Cerium in rats as a model for human osteosarcomas.

Lung metastases were observed in 80% to 85% of rats bearing advanced malignant bone tumours (osteogenic osteosarcomas and angiosarcomas). These tumours were induced in 2-month-old Sprague-Dawley rats by inoculation of a colloidal suspension of radioactive cerium (144Ce) into the hind leg, in close contact to the bones of the knee joint. Twenty-eight rats were killed or died spontaneously shortly after detection of palpable tumours at the site of injection: the incidence of lung metastases was 73.3% and 53.8%, respectively, for osteogenic sarcomas and angiosarcomas, showing that most lung metastases are present at the time of diagnosis of the primary tumour. Tumour-cell kinetic parameters were studied in 49 rats bearing tumours following intraperitoneal injection of [3H]thymidine. The labelling index (LI) of the primary tumours was significantly lower in advanced tumours (7.2% for osteosarcomas and 10.1% for angiosarcomas) than than in tumors examined at the time of detection (12.2% and 13.5%, respectively). Mitotic indices (MI) of all tumours were less than 1%. From the curve of the percentage of labelled mitoses (PLM) at different times after [3H]thymidine injection, Ts (6.5 h) and TG2 (1.75 h) were determined. TC and TG1 were also evaluated (18 h and 9.25 h, respectively). These results show that malignant bone tumours induced in rats with 144Ce may be a good model for human osteosarcomas and may be useful in studying the numerous problems in the therapy of malignant bone tumours in man.

Animals↗
PubMed1981

Acute hemodynamic effects and blood pool kinetics of polystyrene microspheres following intravenous administration.

The acute hemodynamic effect of intravenous administration of polystyrene microspheres was investigated and correlated with their distribution pattern and kinetics. Microspheres of three diameters (3.4, 7.4, and 11.6 micrometer) were administered. The 7.4- and 11.6-micrometer diameter microspheres were filtered by the pulmonary capillary network following intravenous administration, the majority during the first pass. There was no significant hemodynamic effect following administrations of the 7.4- and 11.6-micrometer diameter microspheres in doses as high as 3.0 X 10(9) and 6.1 X 10(8) respectively (total cross-sectional area of 1.3 X 10(11) and 6.4 X 10(10) micrometer2, respectively). Intravenous administration of 3.4-micrometer diameter microspheres produced significant dose-dependent systemic hypotension and depression of myocardial performance at dosages as slow as 1.0 X 10(10) (cross-sectional area of 9.1 X 10(10) micrometer2). These differences in acute hemodynamic effect from the 7.4- and 11.6-micrometer diameter microspheres may be due to the differences in distribution kinetics and fate of the 3.4-micrometer diameter microspheres, which readily pass through the lungs to the spleen. Although elimination of the smaller spheres from the blood during the first 6-8 min was rapid, i.e., t 1/2 = 1.62 and 1.72 min from the venous and arterial blood circulation, respectively, levels of 10(3) spheres/g of blood were present in the circulation for greater than 1 hr. These findings must be considered in the planning of intravenous administration of microspheres as a drug delivery system to target organs.

Animals↗
PubMed1984

Physiologic isolation of the canine proximal fibular epiphysis on a vascular pedicle.

In order to create a model for epiphyseal growth plate transplantation by microvascular technique, a well-defined donor site was established. Dissection of latex-injected adult and juvenile dogs established the vascular supply to the proximal canine fibula. By isolating 7 cm of proximal fibula on the popliteal vessels, the nutrient supply to the epiphyses, metaphysis, and diaphysis is retained. This preserves the nutrient arterial supply to the fibula originating from the cranial tibial artery, the caudal tibial artery, and the small blood vessels from these to the epiphysis. Perfusion of the graft through the defined vascular pedicle was confirmed using 141Ce-labeled microspheres. These results showed a perfusion of the established graft that was as great as or greater than the control, unoperated side. It is concluded that the technique described for isolation can be used for developing a model for vascularized transplantation of epiphyseal growth cartilage in canines.

Animals↗
PubMed1994

The effect of irradiation on blood flow through rabbit submandibular glands.

Microspheres labelled with radioactive isotopes were used to study blood flow through irradiated rabbit submandibular glands before and after injection of pilocarpine. The blood flow through the submandibular glands was measured by the microsphere technique with satisfactory accuracy. A single radiation dose of 13.1 Gy at 3 months of age reduced blood flow through the whole gland significantly 4 months later, and even more at 10 months after irradiation. However, the relative blood flow (per gram of gland tissue) was almost unaffected at both 4 and 10 months post-irradiation with 13.1 Gy because of the simultaneous reduction of gland parenchyma.

Animals↗
PubMed1987

Dietary treatment for decreasing 141Ce body burden in immature rats.

The purpose of this work was to evaluate the effect of prolonged (immediate or delayed) administration of dietary additives to suckling rats on the absorption and retention of radioactive cerium in the body. The experiment was performed on 6-day-old suckling rats. According to dietary treatment the animals were divided into three groups. Each group was artificially fed over 8 h for 6 or 12 days on one of the diets: the first group of animals was fed milk, the second group was given ingredients of rat diet and the third received milk during the first 2 days of the experiment and the ingredients of rat diet afterwards. At the end of the artificial feeding period the pups returned to their mothers and suckled overnight. On the 1st day of the experiment the food was labelled with 141Ce. Whole body radioactivity was determined in a double crystal scintillation counter every 48 h over a 12-day period. Half of the animals from each group were killed 6 days after 141Ce administration and the other half after 12 days. At these intervals retention was determined in the gut, liver, kidneys and femur. The early and delayed administration of rat diet ingredients--fish meal, sunflower meal, alfalfa, cane molasses and premix--greatly reduced whole body retention. The early treatment was more efficacious than the delayed one. The reduction was mostly due to decreased gut retention but organ retentions were also lower. The results obtained indicate that by prolonged (immediate or delayed) administration of some dietary means the retention of radioactive cerium in sucklings can be significantly decreased.

Animals↗