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PubMed1975

[Strontium and calcium metabolism. Interaction of strontium and vitamin D].

Oral administration of strontium to calcium wellfed rats blocks the intestinal absorption of calcium. When high doses of vitamine D are given over long period, the inhibition of calcium intestinal absorption disapears. Under these conditions the absorption of strontium is increased. It is suggested that there is only one absorption mechanism for these two cations. An overdose of the vitamine D increases the renal elimination of strontium but under these conditions the plasma concentration of the strontium is unchanged. Vitamine D brings about the some action on the bone fixation of the strontium as it does on the bone fixation of calcium. The bone fixation is increased with low dosages. The bone fixation is decreased with high dosages.

Animals↗
PubMed2006

Human biokinetics of strontium--part II: Final data evaluation of intestinal absorption and urinary excretion of strontium in human subjects after stable tracer administration.

Fractional intestinal absorption (f1 value) and urinary excretion of strontium in healthy human volunteers has been measured by simultaneous oral and intravenous administration of the stable isotopes 86Sr and 84Sr using the double-isotope method. Final evaluation of the complete data set confirmed that ingestion of different foodstuff and nutritional factors could influence the fractional gut uptake of strontium. In some cases, significant deviations from the f1 value adopted by the International Commission on Radiological Protection (ICRP) were found. The arithmetic mean (+/- standard deviation) of the f1 values of all experiments performed was determined to be 0.46 (+/- 0.24). The probability distribution function of the f1 values is represented by a lognormal curve with a geometric mean of 0.38 and a geometric standard deviation of 2.06. Urinary excretion in all subjects varied depending on the administered foodstuff in a wide range and differs from the ICRP model, up to 2 days after tracer administration. No age or gender dependence of the absorbed strontium fraction and of the urinary excretion of strontium after an oral load was found.

Administration, Oral↗
PubMed2001

Large groundwater strontium flux to the oceans from the Bengal Basin and the marine strontium isotope record.

Strontium concentration and isotopic data for subsurface flowing groundwaters of the Ganges-Brahmaputra (G-B) delta in the Bengal Basin demonstrate that this is a potentially significant source of strontium to the oceans, equal in magnitude to the dissolved strontium concentration carried to the oceans by the G-B river waters. The strontium concentrations of groundwaters are higher by a factor of about 10 than typical G-B river waters and they have similar 87Sr/86Sr ratio to the river waters. These new data suggest that the present contribution of the G-B system to the rise in 87Sr/86Sr ratio in seawater is higher by at least a factor of 2 to 5 than the average over the past 40 million years.

Journal Article↗
PubMed1994

Strontium-90 in antlers of red deer: an indicator of environmental contamination by strontium-90.

The sampling procedures in connection with a very sensitive analytical method are described. Results from different areas in Austria are presented and an interpretion of the results is attempted. Some findings are in accordance with measurements from other substances, some are not. The differences most probably depend on several factors like soil type, precipitation, migration of strontium-90, concentration of stable strontium and calcium. No significant rise in the concentration could be found after 1986 thus in accordance with other measurements of strontium-90 contamination after the Chernobyl accident.

Animals↗
PubMed2003

Chemical and physical characterization by EELS of strontium hexanoate reverse micelles and strontium carbonate nanophase produced during tribological experiments.

Electron energy-loss spectroscopy (EELS) in the analytical electron microscope has been used to characterize nanometre-scale phases of overbased strontium 3,5-dimethylhexanoate reverse micelles and the tribological film obtained during a friction test when the phases are used as lubricant additives. Accurate chemical, molecular and structural information on these materials are deduced by interpreting the EELS near-edge structure. This approach allows confirmation of the composite structure of the micelles, which contain a mineral core and amorphous strontium carbonate surrounded by an organic shell. It also allows identification of the chemical composition and physical structure of the tribological film as an assembly of pure strontium carbonate microcrystals, i.e. strontianite, distributed in an amorphous intergranular phase.

Journal Article↗
PubMedDate not supplied

The effect of stable strontium on the incorporation and metabolism of radioactive strontium in young and adult rabbit bones.

The experiments were performed on 5-, 8-, 12- and 14 months old rabbits. The effect of stable strontium enriched diet on the bone tissue formation (apposition) and on physiocochemical processes consisting in ion exchange were studied using radioactive isotopes: Sr-85 and Ra-226 and tetracycline. The results of kinetic and autoradiographic studies and micoscopical analysis of bone preparations suggest that stable strontium inhibits the mineralization of newly formed bone tissue without affecting the physico-chemical processes related to ion exchange.

Age Factors↗
PubMed2002

Studies of strontium biokinetics in humans. Part 2: uptake of strontium from aqueous solutions and labelled foodstuffs.

The accidental release of radioactive isotopes of strontium, mainly (90)Sr, into the environment and its transfer into the biosphere results in an internal radiation exposure of the affected population. In order to obtain reliable estimates of the committed dose due to an intake of Sr radionuclides, reliable information on its metabolic behaviour inside the human body is needed, i.e. biokinetic data on fractional uptake from contaminated foodstuffs, distribution to and retention in different organs and tissues of the human body. Such information can be obtained by tracer kinetic investigations. The committed effective dose is dependent on the fractional intestinal absorption of the ingested activity (f(1) value). The International Commission on Radiological Protection in its publication ICRP 67 adopted an f(1) value of 0.3 for adults. This study is aimed at investigating if the value corresponds with the actual uptake from contaminated foodstuffs. Aqueous solutions and contaminated vegetables, i.e. cress and salad (lettuce) were used as test materials. For this purpose, the methodology for intrinsic labelling of foodstuffs described in part 1 was applied. For aqueous solutions, a mean f(1) value of 0.63+/-0.14 (mean +/- SD) was obtained by administering 1 mg of strontium. The uptake of Sr from cress intrinsically labelled with about 1 mg Sr almost corresponds to that from aqueous solutions (f(1)=0.62+/-0.10), but from lettuce it is reduced by a factor of 2 (f(1)=0.27+/-0.08).

Adult↗
PubMed1991

Effect of chelating agents on tissue distribution and excretion of strontium following semichronic strontium ingestion.

The effects of repeated ip administration of diethylenetriamine-pentaacetic acid (DTPA), ethylenglycol-bis-(-amino-ethlylether)-N,N'-tetraacetic acid (EGTA), Kryptofix 222, tartaric acid, and Kryptofix 5 on strontium (Sr) excretion and Sr levels in selected mouse tissues were investigated following semichronic strontium nitrate ingestion (284 mg/kg/day) for four weeks. Chelating agents were injected daily for five days at 1/4 of their respective LD50 in two equally divided doses. Only Kryptofix 5 significantly increased the amount of Sr excreted into urine, whereas none of the chelators enhanced the fecal Sr elimination. A significant decrease in the concentration of Sr in bone, the primary tissue of Sr deposition, was observed after treatment with EGTA. Under these experimental conditions, none of the chelators tested was able to remove significant amounts of Sr following Sr ingestion for four weeks.

Animals↗
PubMed1996

Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration.

The analysis of the interaction of strontium (Sr) with bone mineral is of interest because a new agent containing Sr (S 12911) has shown positive effects on bone mass in various animal models of osteoporosis and is currently being developed for preventive and curative treatment of postmenopausal osteoporosis. Iliac bone samples were obtained from 20 male monkeys: 4 untreated control animals, 12 animals sacrificed at the end of a 13-week treatment with high dose levels of S 12911 (750, 275, or 100 mg/kg/day orally), and 4 animals sacrificed 6 weeks after the end of a 13-week treatment with S 12911 (750 or 100 mg/kg/day orally). The distribution of Sr was determined and quantified by X-ray microanalysis. Changes at the crystal level were evaluated by X-ray diffraction and Raman microspectrometry. In the control animals, traces of Sr were found to be homogeneously distributed throughout the bone tissue. In the treated monkeys, Sr could only be detected in calcified matrix. In monkeys sacrificed at the end of the treatment, Sr was found to be dose-dependently incorporated into the mineral substance of the compact and cancellous bone. Sr was heterogeneously distributed with three to four times more Sr in new than in old compact bone, and approximately two and a half times more Sr in new than in old cancellous bone. The bone Sr content dramatically decreased in the animals sacrificed 6 weeks after the end of the treatment. Diffraction showed no significant changes in the characteristics of the crystal lattice. Sr appeared to be easily exchangeable from bone mineral and was slightly linked to mature crystals through ionic substitutions. Even at the highest dose level tested, less than 1 calcium ion out of 10 was substituted by 1 Sr ion in each crystal. In conclusion, taken up by bone, Sr was heterogeneously distributed with a higher concentration in new than in old bone but induced no major modifications of the bone mineral (crystallinity, crystal structure) at the crystal level. As a result, a treatment with S 12911 Sr salt should not induce any alteration of bone mineral.

Administration, Oral↗
PubMed2005

Establishing schedules for repeated doses of strontium and for concurrent chemotherapy in hormone-resistant patients with prostate cancer: measurement of blood and urine strontium levels.

Strontium-89 (Sr-89) alone or with concurrent chemotherapy has a role in the treatment of patients with prostate cancer (PCP). The schedules for repeated doses of Sr-89 or for concurrent chemotherapy is undetermined. The objective of this study was to measure the effective half-life (Te) of Sr-89 using a detector available in a nuclear research facility. Blood and urine samples obtained from PCP treated with Sr-89 (Metastron, Amersham, U.K.) were measured for radioactivity with a High Pure Germanium (HPGe) detector in a gamma spectrometry system (Eurisys, France). Twenty-five urine and 22 blood samples were obtained from 8 patients during a period of 160 days after Metastron injection. Sr-89 radioactivity levels in blood and urine were quite low (<8.2 x 10(-3) microCi/mL) in all patients after 21 days, whereas Sr-85 (available in 0.5% of Metastron) urine and, to a lesser extent, blood radioactivity levels were moderately high and could be detected up to 160 days. Based on Sr-85 urine levels, the calculated Sr-89 Te ranged from 9.6 to 20.7 days. Sr-89 Te can be routinely calculated in PCP based on HPGe detection of Sr-85 radioactivity levels in urine. This measurement can establish schedules for either repeated doses of Sr-89 or concurrent chemotherapy.

Aged↗
PubMed2005

Strontium D-glutamate hexahydrate and strontium di(hydrogen L-glutamate) pentahydrate.

[Sr(C5H7NO4)].6H2O, (I), and [Sr(C5H8NO4)2].5H2O, (II), both crystallize with similar strontium-glutamate-water layers. In (I), the neutral layers are connected through hydrogen bonds by water molecules, while in (II), the positively charged layers are connected through hydrogen bonds and electrostatic interactions by interleaving layers of hydrogen glutamate anions and water molecules.

Journal Article↗