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At least 19 recordsLinked to original sources
PubMed2006

Survey of strontium in mineral waters sold in Japan: relations of strontium to other minerals and evaluation of mineral water as a possible dietary source of strontium.

The concentrations of strontium, calcium, and magnesium in 33 brands of natural mineral waters commercially available in Japan were determined by inductively coupled plasma-atomic emission spectrometry. The geometric mean values were 94.4 microg/L for strontium, 19.1 mg/L for calcium, and 2.82 mg/L for magnesium. Wide confidence intervals of 1.96-4539 microg/L for strontium, 0.865-421 mg/L for calcium, and 0.064-123 mg/L for magnesium were observed. The significant linear relationships among the three elements over a wide distribution range suggest that the synchronized variations of these elements are regulated by the natural ecosystem and not from accidental contamination from human activities or exceptionally high natural sources. Using the results of multiple linear regression analysis, the strontium concentration can be predicted by that of calcium with the appropriate power function. The results of this study suggest that mineral water can be an important nutritional source of strontium. As trace elements imbalance is often found in older patients with chronic renal failure, we propose that close attention of trace elements intake from trendy foods or beverages is necessary to prevent this hidden problem of a rapidly aging society.

Calcium↗
PubMed1995

Strontium excitability of the inner mitochondrial membrane: regenerative strontium-induced strontium release.

Regenerative Sr(++)-induced Sr++ release from isolated rat liver mitochondria was studied using ion-selective electrode techniques. Mitochondria, when exposed to a pulse of Sr++, demonstrated a reversible and transient increase in inner membrane permeability to K+ and H+ ions. The increase in permeability was an all-or-none process with a threshold dependent on the amplitude of the Sr++ pulse. The threshold concentration of Sr++ was lowered from 120-150 microM to 20-30 microM when mitochondria were preloaded with 100 nmoles Sr++/mg protein. Release of matrix-stored divalent cations provided a mechanism for amplification of the extramitochondrial Sr++ concentration (regenerative Sr(++)-induced Sr++ release). The mitochondrial inner membrane became refractory, since subsequent cycles of excitation could not be immediately induced. These experiments demonstrate that the inner mitochondrial membrane is an excitable membrane, with threshold-dependent, regenerative and subsequently refractile Sr(++)-induced Sr++ release characteristics.

Animals↗
PubMed1959

Deposition of strontium-90 through October 1958; the global deposition of strontium-90 is discussed in relation to the absorption of the isotope by man.

It is estimated that the global deposition of strontium-90 increased from 1.9 to 2.6 megacuries during the period from June 1957 to October 1958. During this time the stratospheric reservoir of strontium-90 increased from 1.4 to 4.3 megacuries. Approximately 90 percent of the deposition of debris now stored in the stratosphere will have occurred by 1970. In 1958, the strontium-90 content of powdered milk in the New York area averaged 5.9 micromicrocuries per gram of calcium in comparison with 3.9 micromicrocuries per gram of calcium for the previous year. For this region of the country, the strontium-90 content of milk appears to be increasing in proportion to the strontium-90 content of the soils from which the cows derive their forage. The upper limit of foreseeable contamination in milk can be estimated by assuming that this proportionality will continue until all of the strontium-90 has been deposited from the upper atmosphere. This procedure should yield estimates which tend to err on the side of safety. In this manner, it is estimated that the maximum foreseeable sustained level of milk contamination in the New York area is 11 micromicrocuries per gram of calcium. A child deriving its calcium from dairy sources may be expected to develop a skeleton having 5.5 micromicrocuries per gram of calcium. This estimate is double that made in June 1957 and reflects the increased stratospheric inventory due to U.S.S.R. detonations in 1958. The radiological dose to the skeleton from natural sources such as cosmic rays, radium, potassium, and so forth, is approximately 125 millirems per year. A skeletal burden of 5.5 micromicrocuries of strontium-90 per gram of calcium will deliver a dose of approximately 5.5 millirems per year to the bone marrow. The maximum foreseeable dose from strontium-90 in the New York area is thereby estimated to be about 5 percent of the dose due to natural radioactivity.

Animals↗
PubMed1993

The effect of different strontium concentrations on the efficacy of chlorhexidine-fluoride-strontium gel in preventing enamel softening in vitro.

The effects were compared of strontium concentrations of 0, 15, 50 and 250 parts/10(6) in chlorhexidine(0.20%)-fluoride(0.16%) gel in preventing the softening of bovine enamel during bacterial fermentation. Fresh Streptococcus sobrinus cells were suspended in a buffer solution (pH 6.0) with 3.3% sucrose and centrifuged as a plaque-like layer on the top of enamel slabs covered with 10 microliters gel. AFter 24 h incubation, the pH fall of the fluid was significantly smaller in all test groups than in the placebo group. Strontium seemed to have an inhibitory effect on the pH fall. All test gels significantly prevented softening and dissolution of enamel during bacterial fermentation, which was directly related to strontium concentration. The amounts of calcium and phosphorus in the cells and fluid after incubation were the smallest in the group with 250 parts/10(6) strontium. In a second experiment without bacteria, new enamel slabs were covered with 10 microliters gel containing chlorhexidine and NaF with 0 and 250 parts/10(6) strontium to study the protective effect of strontium. After 24 h gel treatment, each enamel slab was dissolved in 1 ml 0.1 M lactic acid, pH 5.0, for 2 h. Significantly less calcium and phosphorus were dissolved from the enamel in both test groups than in the control and placebo groups. However, the placebo gel also prevented calcium and phosphorus dissolution significantly. These results suggest that the addition of strontium to chlorhexidine-fluoride gel improves the ability of this combination to prevent caries-like enamel softening. The inhibition of bacterial acid production by the strontium-containing gel may explain this enhanced protection of enamel.

Administration, Topical↗
PubMed1992

Lack of effectiveness of several chelators in removing internally deposited strontium from mice following repeated parenteral strontium administration.

Diethylenetriaminepentaacetic acid (DTPA), ethylenglycolbis-(beta-amino-ethylether)-N,N-tetraacetic acid (EGTA), tartaric acid, KRYPTOFIX 222, and KRYPTOFIX 5 were evaluated for their efficacy in mobilization of strontium from the body of mice which had received 20 sc injections of strontium nitrate (95 mg/kg/injection) for 4 w. Twenty-four hours after the last strontium injection, ip administration of 1 of the various chelators or 0.9% saline was initiated and continued daily for 5 d. Mice were housed in metabolic cages, and urine and feces were collected daily for 5 d. After this period, the animals were killed and tissues removed. Tartaric acid, KRYPTOFIX 222, and KRYPTOFIX 5 had no effect on urinary or fecal strontium elimination, whereas DTPA and EGTA significantly decreased the fecal strontium excretion. The concentration of strontium in bone was only lowered in tartaric-treated mice. This study indicates the use of the above chelators is not an effective treatment to enhance the removal of strontium following repeated parenteral strontium administration.

Animals↗
PubMed1957

The effect of carrier strontium on the absorption of oral doses of radioactive strontium in rats.

Carrier strontium had relatively little effect on the retention of an oral dose of radioactive strontium by the rat when it was administered immediately after the radioactive dose. The proportion of the radioactive dose which was excreted in the urine, on the other hand, increased progressively with the carrier dose. There was a decreased uptake of radioactive strontium in rats fed on a special low strontium diet. The effects of dietary strontium are discussed. Evidence was found of a discrimination by the rat against strontium in favour of calcium which was accounted for, at least in part, by a preferential urinary excretion of strontium.

Animals↗
PubMed1963

Strontium-89 and strontium-90 levels in breast milk and in mineral-suplement preparations.

Strontium-90, strontium-89 and S.U. values were determined in human milk before and after the resumption of atmospheric nuclear testings in 1961, and the levels were compared to cows' milk values reported during the same time. S.U.(90) levels in human milk were approximately one-fifth of those found in cows' milk. Assuming an average dietary intake of 11-13 S.U.(90) during the period tested, the mean strontium/calcium ratio of 1.78 found in human milk represents an Observed Ratio milk-diet of approximately 0.14-0.16. Although strontium-89 was present in cows' milk already in September 1961, it did not appear in human milk until November 1961. It seems, therefore, that there was a two-month lag period between the appearance of fresh fallout in cows' milk and human milk. Calcium-supplement mineral preparations used by pregnant and lactating women were tested to find their strontium-89, strontium-90 and S.U. levels, because strontium isotopes, if present in these products, will be transferred to the fetus and to breast-fed infants. The compounds tested had S.U.(90) levels of 0.13-2.62; in none of the preparations was Sr(89) present.

Animals↗
PubMed1998

Accumulation of strontium and fluoride in approximal dental plaque and changes in plaque microflora after rinsing with chlorhexidine-fluoride-strontium solution.

OBJECTIVES: To find out if strontium is incorporated into plaque and enamel in vivo during a 2-week rinsing period with a chlorhexidine-fluoride-strontium solution and to determine the effects of the rinsing on the numbers of mutans streptococci and lactobacilli in plaque. SUBJECTS AND METHODS: A total of 18 adult participants rinsed their mouths twice a day for 2 weeks, first with a placebo solution and subsequently, separated by a 1-week interval without rinsing, with a chlorhexidine gluconate (0.05%)-sodium fluoride (0.04%)-strontium (100 ppm as SrCl2) rinsing solution (CXFSr) for another 2 weeks. RESULTS: After the CXFSr rinsing period the strontium and fluoride contents (microgram g-1 plaque dry weight; mean +/- sr) of approximal plaque were 32.5 +/- 4.7 and 72.8 +/- 9.0, compared with the respective contents of 8.4 +/- 1.2 and 42.0 +/- 4.8 after placebo rinsing (P = 0.0001 for both comparisons). The strontium content remained elevated for 6 weeks. The median proportion of mutans streptococci of approximal plaque of the total viable count of bacteria was 1% after placebo rinsing but decreased to 0.2% after CXFSr rinsing. The proportion of mutans streptococci remained low at 3 weeks (P = 0.018 vs placebo) but had reached the placebo level at 6 weeks. Rinsing with CXFSr solution did not reduce lactobacilli in plaque. The strontium or fluoride contents of the enamel surfaces subjected to tooth brushing did not significantly change. CONCLUSIONS: Strontium and fluoride accumulated in dental plaque during a 2-week CXFSr rinsing period and the proportion of mutans streptococci in approximal plaque was reduced at least for 3 weeks after completion of the rinsing.

Adult↗
PubMed2002

Studies of strontium biokinetics in humans. Part 1: optimisation of intrinsic labelling of foodstuffs with stable isotopes of strontium.

The radioactive isotopes of strontium, mainly (90)Sr, which are common fission products, may significantly contribute to the internal exposure of the population in case of their accidental release into the environment and transfer to the food chain. For (90)Sr, the internal radiation dose is significantly dependent on the fractional absorption of the ingested activity (f(1)-value). Human data on the absorption of dietary strontium and of soluble forms of the element give values ranging from about 0.15 to 0.45 (up to 1.0) for adults. The International Commission on Radiological Protection (ICRP) has adopted f(1)-values of 0.6 for children of less than 1 year of age, 0.4 for children between 1 and 15 years and 0.3 for adolescents above 15 years of age. This study was aimed at investigating how far these values correspond to the actual uptake of strontium from contaminated foodstuffs. A methodology is presented that has been developed for preparing foodstuffs intrinsically labelled with stable isotopes and that will be used in tracer kinetic investigations. The results show that cress and salad can be adequately labelled, i.e. a strontium concentration of 1.36+/-0.47 g per kg of cress (wet weight) and of 0.29+/-0.04 g per kg of salad (wet weight) may be obtained within 15 days and 24 days, respectively. For the biokinetic investigations on humans, applying stable isotopes of Sr as tracers, about 0.1-1 mg strontium is required per volunteer, i.e. a few grams of the edible parts of the labelled material are sufficient.

Air Pollutants, Radioactive↗
PubMed2002

Kinetics of isotopic exchange between strontium polymolybdate and strontium ions in aqueous solution.

A heterogeneous isotopic exchange reaction of strontium polymolybdate in strontium chloride solution was studied using 90Sr as a tracer. The effects of low and high strontium chloride concentration on the rate and mechanism of the isotopic exchange reaction were investigated. It was found that, at high concentrations, the rate is independent of strontium concentration, but, at low concentrations, the rate is proportional to the strontium concentration. These results support a hypothesis that, at low concentrations, the rate is controlled by film diffusion, whereas at high concentrations it is controlled by particle diffusion. Experiments were performed at 293, 303 and 313 K. Activation energy of isotopic exchange reaction and thermodynamic parameters deltaH*, deltaS*, and deltaG* were calculated using the Arrhenius and Eyring equations. The results also indicated that recrystallization is a predominant factor in the present exchange reaction.

Kinetics↗
PubMed1972

An evaluation of strontium chloride, Rappaport and strontium selenite enrichment for the isolation of salmonellas from man, animals, meat products and abattoir effluents.

Strontium chloride enrichment broth was found to be comparable to Rappaport broth for the recovery of a wide range of Salmonella serotypes from man, animals, meat products and effluents. With the exception of cloacal samples from reptiles, both procedures were superior to selenite F.The performance of strontium chloride Mand selenite F enrichment was improved when effluent samples were incubated at 43 degrees C.Strontium chloride M and Rappaport enrichment were superior to selenite F for the isolation of Arizona species from reptiles.Strontium chloride B, strontium selenite and Rappaport broths were found suitable for the isolation of multiple Salmonella serotypes from sea water contaminated with abattoir effluents. The strontium chloride B and strontium selenite enrichment media were superior to Rappaport broth when samples were incubated at 43 degrees C.Modified bismuth sulphite agar was found superior to Salmonella-Shigella agar as a solid subculture medium.The investigation of a food poisoning outbreak due to Salmonella typhimurium phage type 21 is reported.The significance of the choice of sampling and isolation techniques in salmonellosis in man and animals is discussed.

Abattoirs↗
PubMed2004

Strontium biokinetics in humans: influence of alginate on the uptake of ingested strontium.

Radioactive isotopes of strontium, mainly 90Sr, released into the environment due to nuclear accidents may contribute significantly to the internal radiation exposure of members of the public after ingestion of strontium with contaminated foodstuffs. The committed radiation dose is significantly dependent on the fraction of the ingested activity that crossed the gut wall (f1 value). In tracer kinetic investigations, the effect of sodium alginate on the gastrointestinal absorption of strontium was studied in human subjects. Sodium alginate was proven to be a potent agent for reducing strontium absorption with high efficiency and virtually no toxicity. The data obtained show that the uptake of ingested strontium from milk was reduced by a factor of nine when alginate was added to milk. It is concluded that alginate preparations are a suitable antidote against radiostrontium.

Administration, Oral↗
PubMed1995

Effects of strontium on calcium metabolism in rats. II. Strontium prevents the increased rate of bone turnover in ovariectomized rats.

The effects of stable strontium were investigated in ovariectomized (OVX) rats by calcium balance and calcium kinetic studies, histomorphometric analysis and measurements of calcium levels in bone. After 10 days of pair-feeding with a control diet, 71-day-old female Wistar rats were either sham-operated (Sham group) or ovariectomized. The OVX rats were divided into two subgroups: those that were treated with strontium (OVX+Sr group, strontium intake; 87.5 mumol/day/rat) and those that were not (OVX group). Both groups were pair-fed their respective control or strontium diets for 2 weeks. Calcein and tetracycline were injected every 2 weeks from 1 week before ovariectomy to calculate the rate of bone formation in the diaphyseal femora cortex (% BFFC). In the OVX group, urinary calcium and % BFFC decreased, while bone resorption, bone formation and femora length increased at the end of the experiment, as compared with those in the Sham group. No such changes were observed in rats in the OVX+Sr group. The calcium balance, calcium levels in bone and trabecular bone volume in the metaphysis did not change in any of the three groups. These results suggest that strontium may be able to prevent the changes in bone turnover induced by estrogen deficiency.

Animals↗
PubMed1987

Strontium-89 therapy: strontium kinetics and dosimetry in two patients treated for metastasising osteosarcoma.

We report a study of strontium kinetics in two patients who received 89Sr therapy for disseminated osteogenic sarcoma, together with estimates of absorbed dose to the principal metastases and to bone marrow. In neither patient did tumour uptake of strontium have a significant effect on whole-body retention. In one patient, whole-body strontium kinetics agreed closely with the ICRP standard model, while in the second, retention was extremely prolonged, probably due to hypertrophic osteoarthropathy. Strontium-85 scintigraphy, surface counting and high-resolution whole-body profiles agreed in showing that in both patients tumour turnover of strontium was very rapid, with a biological half-life of only a few days. Absorbed dose to tumour was found to be comparable in magnitude to the mean bone-marrow dose. We have no reason to believe that 89Sr therapy was of clinical benefit to either patient.

Adolescent↗