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PubMed1983

[Cesium-137 and strontium-90 from nuclear weapon fallout using tobacco as an example].

42 to 75 pCi cesium-137 and 702 to 903 pCi strontium-90 per kg were found in samples of tobacco of German origin and from commercial cigarette. The presence of these radionuclides in tobacco is attributed to the fallout from nuclear explosions. Taking into consideration mean transfer rates of the radionuclides in the main stream smoke condensate and average consumption of cigarettes, whole body radiation doses for inhalation have been calculated to be in the range 10(-3) to 10(-4) mrem/year and per person. This means, they are in the same order of magnitude as radiation doses by inhalation of ambient air. They are smaller by a factor of 10(-4) than the radiation exposure due to ingestion of these radionuclides from the total diet.

Cesium Radioisotopes↗

PubMed1983

Strontium-90 and caesium-137 in Indian tea.

The paper presents results of measurements made on tea samples, collected during 1961-1979 period for their strontium-90 and caesium-137 content. Tea was found to contain higher concentration of these radioisotopes compared to other food-stuffs having vegetative origin. Levels in tea are compared with those in leafy vegetables from both India and Japan. Interpretation for higher concentrations in tea compared to leafy vegetables is briefly given on the basis of agro-climatic conditions. The levels are also considered from the point of view of health hazard.

Cesium Radioisotopes↗

PubMed1980

Transcapillary exchange and retention of fluoride, strontium, EDTA, sucrose, and antipyrine in bone.

The extractions of 85Sr2+, 18F-, sucrose-14C, EDTA-51Cr, and antipyrine-14C in bone were determined by the multiple indicator-dilution method. Fluoride and strontium extractions were 18 to 70% during a single transcapillary passage, and those of EDTA and sucrose were from 11 to 59%, whereas extraction of antipyrine was 87%. Injections of 85Sr2+ and 18F- made when perfusion was done alternately with blood and plasma resulted in similar fractional extractions. When flow and extraction were measured simultaneously, extraction was related inversely to flow.

Animals↗

PubMed1994

Production of immortal human endothelial cell lines by strontium phosphate transfection and electroporation of SV40 sequences.

Eleven human endothelial cell lines have been produced by introducing sequences from the DNA tumor virus SV40 into human umbilical vein endothelial cells either by strontium phosphate coprecipitation or electroporation. The resultant lines were confirmed as being endothelial in origin by their production of endothelial-specific von Willebrand factor. The growth characteristics of the different lines in normal and reduced levels of serum was determined, as was their cellular response to endothelial cell growth supplement in combination with heparin, basic fibroblast growth factor, transforming growth factor-alpha, and epidermal growth factor.

Antigens, Polyomavirus Transforming↗

PubMed1992

ATP-dependent strontium uptake by basolateral membrane vesicles from rat renal cortex in the absence or presence of calcium.

ATP-dependent Sr2+ transport was examined in vitro using basolateral membrane (BLM) vesicles isolated from rat renal cortex to clarify the discrimination mechanisms between strontium (Sr) and calcium (Ca) in renal tubules during reabsorption. ATP-dependent Sr2+ uptake and Ca2+ uptake were observed in renal BLM vesicles and were inhibited by vanadate. Hill plots indicate similar kinetic behavior for Ca2+ and Sr2+ uptake. The apparent Km and Vmax of ATP-dependent Sr2+ uptake were both higher than those for Ca2+ uptake. ATP-dependent Sr2+ uptake by BLM vesicles diminished in the presence of 0.1 microM Ca2+ and was more markedly inhibited by 1 microM Ca2+. Hill plots of Sr2+ uptake data with and without 0.1 microM Ca2+ showed that the cooperative behavior of Sr2+ uptake was not changed by Ca2+. In the presence of 0.1 microM Ca2+, the affinity of the transport system for Sr2+ and the velocity of Sr2+ uptake in the BLM were both decreased. However, the rate of Ca2+ uptake was not diminished by Sr2+ concentrations of less than 1.6 microM. These results suggest that Ca2+ is preferentially transported in the renal cortex BLM when Ca2+ and Sr2+ are present at the same time.

Adenosine Triphosphate↗

PubMed1999

Acquisition of improved reference values for cesium, iodine, strontium, thorium, and uranium in selected NIST reference materials.

As part of a study on the ingestion and organ content of some trace elements of importance in radiological protection, additional work has been undertaken to acquire improved reference values for cesium, iodine, strontium, thorium, and uranium in four selected reference materials provided by the US National Institute of Standards and Technology. The materials are SRM-1548 Total Diet, SRM-1548a Typical Diet, SRM-1486 Bone Meal, and RM-8414 Bovine Muscle. A coordinated study was undertaken with the help of seven selected laboratories in five countries. Instrumental and radiochemical neutron activation analysis and inductively coupled plasma-mass spectrometry were the analytical main techniques used.

Animals↗

PubMed1989

Renal discrimination between strontium and calcium in rats. Effects of renal damage caused by cadmium-metallothionein.

Renal functions were damaged at the reabsorptive site by the injection of cadmium-metallothionein (Cd-MT) and its effect on discrimination of chemically similar elements was examined for the two alkaline-earth elements, calcium (Ca) and strontium (Sr). Tubular damage was induced in female Wistar rats, 7 wk old, body wt 145.1 +/- 3.5 g (mean +/- S.D.), by an intraperitoneal injection of Cd-MT (400 micrograms Cd/kg body wt). The Cd-MT injection caused increases in urinary enzymes (lactate dehydrogenase; alkaline phosphatase), glucose, and total protein. Urinary Ca and Sr increased and urinary Sr/Ca ratio decreased rapidly after the Cd-MT injection. Both changes remained at significant levels throughout the experiment. On the other hand, renal Ca and Sr levels increased with time after 18 or 24 h and changed similarly. Although plasma levels of Ca and Sr slightly increased after 30 or 36 h post-injections, the plasma Sr/Ca level remained constant. A close exponential relationship formed between the relative clearances of Ca and Sr. There was no significant difference between the exponent of the following equation (K) for the Cd-MT-injected group and that for the control group. Sr clearance/creatinine clearance = (Ca clearance/creatinine clearance)K where K = 0.408 from experimental data for the two groups. This suggests that the discrimination mechanism between Sr and Ca during the reabsorptive step in the kidney is strictly regulated.

Alkaline Phosphatase↗

PubMed1990

Clastogenic activity of strontium chloride on bone marrow cells in vivo.

Oral administration of different concentrations of Strontium chloride to laboratory bred mice in vivo induced chromosomal aberrations in bone marrow cell metaphase preparations. The degree of clastogenicity was directly proportional to concentration used at 6, 12, and 24 h of treatment. Duration of treatment could only be related positively in the lower doses. The females showed greater susceptibility than the males at all concentrations used.

Animals↗

PubMed1990

Age-related changes in strontium to calcium ratios in rat tissues.

The Sr/Ca ratios in plasma, urine, bone, and soft tissues for various ages after weaning in male and female rats were determined to examine the effects of aging on the discrimination between strontium (Sr) and calcium (Ca) under physiological conditions. Age-related changes in the Sr/Ca ratios were similar in all tissues; the Sr/Ca ratios decreased rapidly until about 25-wk-old and then slowly, from that period on, reaching much lower values than in the diet. When the logarithm of the Sr/Ca ratio in each tissue was plotted against the logarithm of age, a linear relationship was observed with statistically significant (p less than 0.05) regression lines. The higher levels of Sr/Ca ratios in all tissues of the younger rats could be explained by the high efficiency of Sr absorption by the small intestine early in life. Parameters for the equations between age and Sr/Ca ratio differed with tissues, suggesting the existence of specific discrimination mechanisms in each tissue.

Aging↗

PubMed1991

Biological discrimination between calcium and strontium in kidneys and bone of young and adult rats.

Effects of aging on the biological discrimination between calcium (Ca) and strontium (Sr) by the kidneys and bone were studied in male and female rats of 5 to 50 wk of age by examining Sr/Ca ratios in the plasma, urine, and bone. The Ca-Sr discrimination at the reabsorption process in the kidneys was not affected by aging in male or female rats. On the other hand, discrimination between the two elements was shown to be age-related at the absorption process in the digestive tract, and became more strict with age. The reverse situation was observed in the discrimination of Ca and Sr in the femur; younger rats discriminated the two elements more strictly than older animals.

Aging↗

PubMed1991

Discrimination between strontium and calcium in suckling rats.

Discrimination between strontium (Sr) and calcium (Ca) was examined in suckling rats and compared with that in older rats after weaning. Concentrations of Sr and Ca and the Sr/Ca ratios in serum and femur of 10-d old and 21-d old rats were determined. The Sr concentrations and Sr/Ca ratios in the serum and femur of 10-d old rats were lower than those of 21-d old rats, that could be explained by the fact that 10-d old rats ingested only maternal milk in which the Sr/Ca ratio was much lower than the laboratory diet. The relative ratios of Sr/Ca in serum and femur to that in the diet were found to be higher in 10-d old rats compared with those in 21-d old rats, and also higher than those in the older rats after weaning, as described in our previous publication. This result may reflect that discrimination between Sr and Ca during intestinal absorption is lacking in very young animals before weaning and develops after this age. Renal discrimination between Sr and Ca in the suckling rats at 10 d of age was evaluated by determining the relationship between the relative clearances of Ca and Sr. The mathematical model proposed by Walser and Robinson was applied on these results and the parameter for the equation, that is, the discrimination constant, was shown to be higher in 10-d old rats compared to those in young (7 wk of age) and adult (25 wk of age) rats. This result suggests that the discrimination of Sr in favor of Ca during the tubular reabsorptive process may not be fully developed in the very young rats before weaning.

Age Factors↗

PubMed2001

Nickel and strontium nitrates as modifiers for the determination of selenium in wine by Zeeman electrothermal atomic absorption spectrometry.

A mixed matrix modifier of nickel and strontium nitrates was used as a chemical modifier for the determination of selenium in wines by Zeeman electrothermal atomic absorption spectrometry. Wine samples were heated on a boiling water bath with small amounts of nitric acid and hydrogen peroxide. For complete elimination of interference, especially from sulfates and phosphates, selenium is complexed with ammonium pyrolidinedithiocarbamate (APDTC), extracted into methyl isobutyl ketone (MIBK), and measured by ETAAS. The graphite furnace temperature program was optimized for both aqueous and organic solutions. Pyrolysis temperatures of 1300 degrees C and 800 degrees C were chosen for aqueous and organic solutions, respectively; 2700 degrees C and 2100 degrees C were used as optimum atomization temperatures for aqueous and organic solutions, respectively. The optimum modifier mass established is markedly lower than those presented in the literature. The platform atomization ensures pretreatment stabilization up to 1100 degrees C and 1600 degrees C, respectively, for organic and aqueous selenium solutions. The procedure was verified by the method of standard addition. The investigated wine samples originated from the different regions of the Republic of Macedonia. The selenium concentration varied from not detectable to 0.93 microg L(-1).

Hot Temperature↗

PubMed2004

Effects of strontium on the physicochemical characteristics of hydroxyapatite.

In a previous experimental study using a chronic renal failure rat model, a dose-related multiphasic effect of strontium (Sr) on bone formation was found that could be reproduced in an in vitro set-up using primary rat osteoblasts. The results from the latter study allowed us to distinguish between a reduced nodule formation in the presence of an intact mineralization at low Sr-doses (1 microg/ml) and an interference of the element with the hydroxyapatite (HA) formation at high doses (20-100 microg/ml). To further investigate the latter effect of Sr on physicochemical bone mineral properties, an in vitro study was set up in which the UMR-106 rat osteosarcoma cell line was exposed to Sr, added to the cell culture medium in a concentration range varying between 0-100 microg/ml. Temporal growth and functionality of the culture was investigated by measurement of the alkaline phosphatase activity and calcium (Ca) concentration in the culture medium (used as an index of Ca-incorporation, i.e., HA formation) at various time points. At the end of the culture period (14 days post-confluence), samples of the mineralized cultures were taken for further analysis using X-ray diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR). Synthetic HA doped with various Sr concentrations (based on the cell culture and previous experimental studies and yielding Sr/(Sr + Ca) ratios ranging from 0-60%), was prepared and examined for crystal growth and solubility. Crystal size was assessed using scanning electron microscopy (SEM). Ca incorporation indicated a reduced mineralization in the 20 and 100 microg/ml Sr groups vs. controls. Sr-doped synthetic HA showed a significant dose-dependent reduction in crystal growth, as assessed by SEM, and an increase in solubility, apparent from 12.7% Sr/(Sr + Ca) on. Moreover, in both mineralized cultures and synthetic HA, XRD and FTIR analysis showed a reduced crystallinity and altered crystal lattice at similar concentrations. These new data support our previous in vivo and in vitro findings and point to a potential physicochemical interference of Sr with HA formation and crystal properties in vivo.

Alkaline Phosphatase↗

PubMed2002

Strontium-89 (Metastron) and the bisphosphonate olpadronate reduce the incidence of spinal cord compression in patients with hormone-refractory prostate cancer metastatic to the skeleton.

Spinal cord compression (SCC) is a devastating complication of metastatic cancer. We investigated the potential beneficial effect of two palliative therapies--strontium-89 (Metastron) and the nitrogen-containing bisphosphonate olpadronate--on the incidence of SCC in hormone-refractory prostate cancer (HRPC) metastatic to the skeleton. We retrospectively studied 415 patients with histologically proven prostate cancer who underwent bone scintigraphy at the time of diagnosis and were followed up at the Leiden University Medical Center between 1990 and 1999. Medical or surgical castration was undertaken in 172 patients with evidence for skeletal metastases. Within 2 years, 147 of these patients (85%) developed HRPC associated with severe progressive bone pain. Palliative treatment was given to 131 patients in the form of local radiotherapy ( n=10), 89Sr ( n=46) or intravenous olpadronate ( n=66), with ( n=57) or without ( n=9) maintenance oral olpadronate. Nine patients received both 89Sr and olpadronate at various intervals. Sixteen patients who did not receive any of these treatments were used as historical controls. There was no significant difference in baseline characteristics between treatment modalities. The incidence of SCC was 17% in the whole group, and highest in controls receiving no palliation (50%). None of the patients treated with local radiotherapy, only 4% of patients receiving 89Sr and 21% of patients given olpadronate developed this complication. Our findings suggest a significant reduction in SCC in patients with symptomatic HRPC metastatic to the skeleton who receive palliative therapies. Local radiotherapy completely prevents the incidence of SCC, 89Sr leads to an important decrease in this complication and olpadronate induces a significant, albeit smaller decrease in the incidence of SCC. The use of these agents opens new avenues in the difficult management of patients with advanced prostate cancer who are most at risk of developing SCC.

Aged↗

PubMed1997

Gamma camera imaging of osseous metastatic lesions by strontium-89 bremsstrahlung.

The aim of this study was to optimise the parameters affecting the Bremsstrahlung scintigraphy of patients injected with strontium-89 chloride. The parameters considered were : (1) instrumental detection efficiency, and (2) tissue attenuation factor for 89Sr calibrated sources, which permit quantitative evaluation of the activity in a given bone lesion. Some typical examples of in vivo 89Sr imaging are presented to illustrate the clinical utility of the imaging procedure developed by us, which is implemented in our department for all patients treated with 89Sr chloride.

Bone Neoplasms↗

PubMed1998

The effect of repeated strontium-89 chloride therapy on bone pain palliation in patients with skeletal cancer metastases.

One hundred and eighteen patients with painful skeletal metastases of malignant diseases (predominantly prostate, breast and lung cancer) were treated with 150 MBq of strontium-89 chloride (Metastron, Amersham, UK) intravenously. The results were evaluated according to a score considering pain relief, mobility, analgesic intake and general feeling. In only five patients (4.2%) was no improvement observed; mild improvement was noted in 48 (40.7%), and substantial or complete improvement in 56 (47.5%) and 9 (7.6%), respectively. The mean painless period after a single 89SrCl dose was 3.3 +/- 2.28 months (in patients with prostate, lung, breast and other types of cancer it was 3.65 +/- 2.11, 3.29 +/- 1.27, 3.08 +/- 0.48 and 3.44 +/- 1.36 months, respectively). During a 3-year study, 89SrCl treatment was successively repeated up to 5 times in some patients (total number of Metastron applications was 256) who benefited from the first Metastron administration and did not show signs of myelosuppression. Even after repeated treatment, relief was consistent and the duration of the period without pain increased (in particular in patients with breast cancer, in whom the period of relief was prolonged from 3.08 +/- 0.48 months after the first dose to 5.33 +/- 2.36 months after the fifth 89SrCl administration). The increased painless period was not observed after repeated treatment in the patient group comprising miscellaneous types of cancer, and the degree of improvement was less apparent. During the course of successive 89SrCl treatments, transient signs of myelosuppression indicated by a decrease in white cell and thrombocyte counts of at least 25% were observed 10 times after Metastron administration (twice in two patients), i.e. in 3.9% of all 89SrCl administrations; these transient haematological changes of moderate grade were closely connected with Metastron administration. Palliative treatment of metastatic skeletal pain with 89SrCl improves the quality of life in most patients suffering from prostate, lung and breast cancer and may be safely repeated with the same benefit and without significant myelosuppression. The beneficial effect of 89SrCl treatment seems to be less pronounced in other types of cancer with painful skeletal metastases.

Adult↗

PubMed2000

Effects of strontium on the absorption of calcium, magnesium and phosphate ions from the ovine reticulo-rumen.

The net absorption rates of strontium ions from the ovine reticulo-rumen, isolated in situ in trained conscious animals, were measured under controlled conditions. A linear positive response was obtained from the addition of Sr2+ ions to the artificial rumen fluid. This increase in the absorption of Sr was reflected in an increase in the plasma Sr concentration. In contrast to the discrimination observed elsewhere in favour of the absorption of Ca relative to Sr, the absorption rate of Sr from the reticulo-rumen was significantly greater than that of Ca, from solutions containing the same molar concentration. A graded increase in the Sr concentration in the ruminal fluid from 1 mmol/l to 4 mmol/l led to a corresponding reduction in the absorption rate of Ca but an increase in that of phosphate. The latter result is similar to that observed when the intra-ruminal concentration of Ca2+ ions is increased. It is suggested that Ca and Sr share a common pathway for absorption from the reticulo-rumen and that this may involve coupling with the absorption of phosphate ions.

Animals↗

PubMed2000

Strontium metabolism in teeth and enamel dose assessment: analysis of the Techa river data.

People living on the banks of the Techa river were exposed to 90Sr in the early 1950s. Data obtained by radiochemical measurements of extracted permanent teeth, 90Sr autopsy measurements in bone and tooth samples, in vivo measurements of surface beta activity of the anterior teeth and whole-body counter (WBC) measurements of 90Sr in the skeleton have been analyzed. Surface beta activity measurements indicate a biological half-life of 90Sr of about 35 years in enamel. The WBC measurements have been performed since 1974 and a model for the age-dependent strontium retention in human bone has been used to extrapolate to previous time periods when the other measurement results were obtained. For the first decade after the intake, the ratio of the 90Sr concentrations in teeth and bones were found to decrease with age at the time of major intake, from about 10 for 1-year-old children to about 0.3 for adults. There was a considerable variability of individual data within each age group. For adults, the correlation between 90Sr in skeleton and teeth was not high at 0.47 according to radiochemical data for posterior teeth (molars and premolars) and 0.43 according to measurements of surface beta activity for anterior teeth. For children and adolescents there was no correlation between individual measurements in the skeleton and teeth. The absorbed dose in enamel due to 90Sr in dentine has been calculated by Monte Carlo simulations of the electron transport. The results are in agreement with EPR measurements of the absorbed dose in the enamel of persons exposed, mainly due to 90Sr ingestion.

Adolescent↗