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PubMed2003

Linking cesium and strontium uptake to kaolinite weathering in simulated tank waste leachate.

Weathering behavior of kaolinite was studied in batch systems under geochemical conditions characteristic of tank waste released to the vadose zone at the Hanford Site, WA (0.05 M Al(T), 2 M Na+, 1 M N03-, pH approximately 14, Cs+ and Sr2+ present as co-contaminants). Time series experiments were conducted from 0 to 369 d, with initial Cs+ and Sr2+ concentrations ranging from 10(-5) to 10(-3) M. Dissolution of kaolinite increased soluble Si and Al to maximum levels at 7 d (Cs and Sr concentrations of 10(-5) and 10(-4) M) or 33 d (Cs and Sr concentrations of 10(-3) M). Subsequent precipitation of Si and Al was coupled to the formation of oxalate-extractable solids that incorporated Cs and Sr. Strontium sorption was nearly complete within 24 h for initial Sr concentrations (Sr0) < or = 10(-4) whereas Cs uptake increased over the full year of the experiment for all initial Cs concentrations. Spectroscopic analyses revealed neoformed solids including the zeolite Na-Al silicate (Al-chabazite), and feldspathoids sodium aluminum nitrate silicate (NO3-sodalite), and sodium aluminum nitrate silicate hydrate (NO3-cancrinite), which can incorporate Cs. Single-pulse 27Al solid-state nuclear magnetic resonance (NMR) spectroscopyyielded first-order rate constants (k)for mineral transformation that decreased from 3.5 x 10(-3) to 2 x 10(-3) d(-1) as Cs and Sr concentrations were increased from 10(-5) to 10(-3) M. Discrete strontium silicate solids were also observed. The incongruent dissolution of kaolinite promoted the sequestration of contaminants into increasingly recalcitrant solid phases over the 1-yr time period.

Adsorption↗

PubMed2005

A nearly planar water sheet sandwiched between strontium-imidazolium carboxylate coordination polymers.

The crystal structure of a strontium-imidazolium polymeric material obtained from the reaction of zwitterionic 1,3-bis(carboxymethyl)imidazolium with SrCO(3) (2:1) in water is reported. The compound crystallized in the orthorhombic space group Pcc2 with a = 14.545(3) A, b = 8.514(5) A, c = 8.5619(14) A, V = 1060.2(6) A(3), and Z = 2. The macromolecular structure is constructed from 8-coordinate strontium, which binds to six different imidazolium carboxylate molecules. The two-dimensional polymer is separated by water sheets in which the water molecules form near-planar hexagons.

Carbonates↗

PubMed1999

Visual function after strontium-90 plaque irradiation in patients with age-related subfoveal choroidal neovascularization.

PURPOSE: To report 2-year visual and angiographic results in eyes treated with strontium plaque irradiation for subfoveal choroidal neovascular membranes (CNVM) in age-related macular degeneration. METHODS: Twenty eyes with recent subfoveal CNVM were treated with local irradiation. The impact of the treatment on visual function was evaluated by visual acuity, contrast sensitivity and reading speed testing. RESULTS: At 12 months visual acuity had improved or remained the same in 9/ 20 eyes (45%). At 24 months visual acuity was stable in 5/18 eyes (28%). Eyes with signs of CNVM regression (13/18, 72%) lost a mean of 3.3 lines, but eyes with recurrent CNVM lost a mean of 5.1 lines of vision. The mean contrast sensitivity was better in the irradiated eyes than in the fellow eyes with late age-related macular degeneration at 24 months. Six of 17 irradiated eyes (35%) could read at least some words at 24 months. CONCLUSIONS: Visual function decreases in patients treated with strontium irradiation, but less in eyes showing regression of the CNVM than in eyes with further growth of the CNVM.

Aged↗

PubMed2003

Dose-dependent effects of strontium on osteoblast function and mineralization.

BACKGROUND: Strontium-ranelate is now being used in the treatment of osteoporosis in elderly patients. As the majority of these patients already have a decreased renal function they are at an increased risk for accumulation of the element. Recent findings from epidemiologic studies in dialysis patients and experimental data obtained in a chronic renal failure (CRF) rat model established a dose-related multiphasic effect of strontium (Sr) on bone formation. To confirm these in vivo findings an in vitro set-up, consisting of primary rat osteoblast cultures, was applied. Sr was added to the culture medium at concentrations of 0, 0.5, 1.0, 2.0, 5.0, 20, and 100 microg/mL, respectively. METHODS: Calcium incorporation (index of mineralization) and alkaline phosphatase activity were determined in the medium during the culture period, while at the end of the experiment, nodule formation (mineralized + unmineralized area) was quantified using a digital imaging system. mRNA synthesis of various osteoblast specific genes was assessed by means of reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Compared to the control group (0 microg/mL Sr), a significantly reduced nodule formation in the presence of an intact mineralization was found for the lowest 0.5 and 1 microg/mL Sr doses, suggesting an impaired in vitro osteoblast differentiation. Both nodule formation and mineralization were normal for the 2 and 5 microg/mL doses. For the highest Sr doses (20 and 100 microg/mL) a reduced mineralization was observed in the presence of an intact nodule formation indicating an inhibitory effect on the hydroxyapatite formation. The alkaline phosphatase activity reflected the multiphasic pattern of the nodule formation while the calcium incorporation corresponded with the pattern of nodular mineralization. No variations in cell proliferation were found. RT-PCR revealed that Sr interfered with the osteoblast at the level of the mRNA synthesis of several relevant genes. CONCLUSION: Using the proposed in vitro model we confirmed the multiphasic effect of Sr on bone formation previously demonstrated in a CRF rat model. The data presented allow us to suggest that at low concentrations Sr interferes with the bone formation at the level of cell differentiation, whereas at high concentrations the disturbed mineralization in the presence of an intact nodule formation is indicative for a physicochemical interference of Sr with the hydroxyapatite formation.

Alkaline Phosphatase↗

PubMed2002

Long-term treatment with strontium ranelate increases vertebral bone mass without deleterious effect in mice.

It was previously shown that strontium ranelate (SR; S12911-PROTOS, Institut de Recherches Internationales Servier, Courbevoie, France) can modulate bone metabolism in rats and mice. To determine the long-term effects of SR on vertebral bone metabolism in adult mice, the compound or the vehicle was given in the diet to normal male and female mice for 104 weeks at the dose of 200, 600, or 1,800 mg/kg/d corresponding to 0.78, 2.34 or 7.01 mmol Sr(2+)/kg/d. SR dose-dependently increased plasma strontium concentration, as well as exposure to the drug. Histomorphometric analyses of indices of bone volume, bone formation, and resorption were determined in the endosteal vertebral bone. SR significantly increased the trabecular bone volume by 25% and 59% in females treated with SR 600 and 1,800 mg/kg/d, respectively. This was associated with a 27% and 62% increase in mineralized bone volume. Bone volume was also significantly increased by 17% and 38% in male mice treated with SR 200 and 1,800 mg/kg/d, respectively. In parallel, SR increased the osteoblastic surface by 131% in males. In addition to this stimulatory effect on bone formation, a 52% decrease in osteoclastic surface, and a dose-dependent decrease in osteoclastic number (30% to 47%), was observed in female mice. Finally, SR even at the highest dose tested did not alter the osteoid thickness, indicating no deleterious effect on bone mineralization. Altogether, these findings show that SR simultaneously increases bone formation and decreases bone resorption in male or female mice, which results in increased vertebral bone mass in both genders without deleterious effect on bone mineralization.

Administration, Oral↗

PubMed1995

Selective accumulation of strontium-89 in metastatic deposits in bone: radio-histological correlation.

The systemic administration of 89Sr has proven effective in the palliation of painful osseous metastases. Biodistribution studies with the gamma-emitter 85Sr suggest that both its uptake and retention are increased in bone metastases, where increased mineral turnover takes place. To study the pattern and nature of this process further, bones containing metastatic deposits were obtained from three patients who had previously been treated with 148 MBq of 89Sr. The bones were cut into 0.5-1.0 cm sections. The cut surfaces which faced together were marked with India ink, and adjacent sections were submitted for histology and autoradiography. Strontium deposition and retention were observed in regions which exhibited significant osteoblastic activity, mostly in areas adjacent to metastatic deposits, but also in subchondral and endosteal locations, as well as in an area corresponding to a pathological fracture with callus formation. With these exceptions, strontium deposition was not observed in histologically normal bone or within the marrow. Our findings demonstrate directly the selective nature of accumulation and retention of 89Sr and confirm previous clinical impressions.

Adenocarcinoma↗

PubMed1984

Strontium, nifedipine and 4-aminopyridine modify the time course of the action potential in cells from rat ventricular muscle.

Action potentials, initiated by brief depolarizing pulses, were recorded from single cells isolated from rat ventricular muscle. These action potentials showed a rapid upstroke to about +30 mV, followed by two phases of repolarization referred to as the early and late phases of the action potential. Nifedipine (1 microM), which blocks the second inward current (Isi) carried by Ca in these cells, shortened the early phase. Substitution of strontium for calcium in the solution bathing the cells, a procedure which prolongs Isi, prolonged the early phase. 4-Aminopyridine (1 mM), which inhibits transient outward current, prolonged the early phase with either calcium or strontium in the external solution. It is concluded that both Isi and transient outward current contribute to the early phase of the action potential in rat ventricular muscle. It is also suggested that Isi does not directly contribute to the late phase, since the characteristics of the late phase are not compatible with such a role, and the possibility of additional inward current is investigated in the accompanying paper (Mitchell et al., 1984).

4-Aminopyridine↗

PubMed1997

Dentine hypersensitivity and the placebo response. A comparison of the effect of strontium acetate, potassium nitrate and fluoride toothpastes.

A considerable number of varied agents are apparently effective in the treatment of dentine hypersensitivity. In particular, the literature supports the efficacy of strontium, potassium and fluoride containing toothpastes. This study was a double-blind, randomised, parallel group comparison of three products, namely strontium- and potassium-based desensitising toothpastes both containing fluoride, and a conventional fluoride toothpaste. A total of 131 subjects entered a 4-week wash-in phase using the conventional fluoride toothpaste, of whom 120 entered a 6-week treatment phase. Sensitive teeth were evaluated at wash-in baseline, treatment baseline and after 2 and 6 weeks use of the treatment pastes. Dentine hypersensitivity was assessed with tactile and cold air stimuli together with an overall subjective assessment. Analysis of the findings was performed using non-parametric statistical methods. Of the original 120 subjects, 112 completed the trial. All 3 toothpaste groups showed reductions in sensitivity over the 6 weeks; however, no significant differences were found between the three products at any given time. Interestingly, there was no significant change in sensitivity between wash-in baseline and treatment baseline for the cold air stimulus with the fluoride-only-based paste. However, for the group using the same fluoride toothpaste, there was significant improvement between wash-in baseline and week 6, and treatment baseline and week 6 for this stimulus, suggesting a substantial placebo effect occurred. There is a need for further investigation of a wash-in period and examination of the placebo effect when evaluating dentine hypersensitivity trials.

Acetates↗

PubMed1973

Release of noradrenaline from slices of cat spleen by pre-treatment with calcium, strontium and barium.

1. Spleen slices pre-incubated for different periods at 4 degrees C in Krebs solution containing varying concentrations of calcium, up to 96 mM, lost their endogenous noradrenaline stores when reincubated in normal Krebs solution at 37 degrees C for 2 hr. Rate of loss of noradrenaline was roughly related to the calcium concentration of the pre-incubation medium and the pre-exposure time.2. Pre-treatment with isotonic barium or strontium (96 mM) Krebs solution also induced release of noradrenaline from spleen slices when re-exposed to normal Krebs solution. Barium was more effective than either calcium or strontium.3. The enhanced release induced by calcium pre-treatment occurred in the absence of calcium, with or without EGTA.4. Tissue calcium concentration of spleen slices was 0.68 m-mole/kg. Pre-treatment of slices with normal or 96 mM calcium-Krebs solution for 4 hr at 4 degrees C increased the calcium concentration to 2.57 and 9.9 m-mole/kg, respectively.5. Ouabain, which caused a dose-dependent release of noradrenaline, did not modify the release induced by calcium pre-treatment.6. Spleen slices prepared from cats anaesthetized with sodium pentobarbitone instead of ether were resistant to noradrenaline depletion by calcium pre-treatment.7. Evoked release of [(3)H]noradrenaline by high potassium from calcium-pre-treated slices did not occur in the absence of external calcium, even though the calcium pre-treatment enhanced the tissue concentration of this ion by nearly tenfold.8. Net uptake of noradrenaline in normal and in treated slices whose noradrenaline content was severely reduced by barium pre-treatment or sodium withdrawal was comparable.9. Specific activity of released and endogenous [(3)H]noradrenaline increased as the tissue stores of noradrenaline were reduced.10. It is suggested that the spontaneous loss of tissue noradrenaline after pre-treatment with high-calcium solution was due to inhibition of sodium-potassium-activated ATPase by intracellular accumulation of calcium ions. Evidence is presented to suggest that vesicles depleted of their endogenous transmitter by pre-treatment with calcium, strontium or barium, or by sodium withdrawal, are re-used for the storage and release of exogenous noradrenaline.

Acetates↗

PubMed1959

Effect of strontium replacement for calcium on production of motile cells in Protosiphon.

Protosiphon botryoides Klebs grows without evident zoosporogenesis in inorganic media in which strontium is substituted for calcium. Growth is 50 to 90 percent of that obtained with calcium; when sodium is substituted for calcium, there is no appreciable growth. Motility was observed at or above CaCl(2). 2H(2)O levels of 5 mg/lit., with or without strontium.

Calcium↗

PubMed1969

Strontium-90: concentrations in surface waters of the Atlantic Ocean.

From the large body of analyses of strontium-90 in surface waters of the Atlantic Ocean, annual average concentrations (from 10 degrees N to 70 degrees N) have been compared to those predicted. The data indicate higher fall-out over ocean than over land and confirm the rapid rates of down-mixing shown by most studies of subsurface strontium-90.

Oceanography↗

PubMed1969

Strontium-90 concentration factors of lake plankton, macrophytes, and substrates.

The ratio of concentration of strontium-90 in living and inert lake components to that in lake water (concentration factors) was determined for plankton, macrophytes, and substrates in eutrophic, mesotropric-eutrophic, and dystrophic Latgalian lakes. Concentration factors of strontium-90 in aquatic organisms and substrates are higher in a dystrophic lake than in the other types.

Geological Phenomena↗

PubMed1970

Phylum ectoprocta, order cheilostomata: microprobe analysis of calcium, magnesium, strontium, and phosphorus in skeletons.

Calcium, magnesium, and strontium occur in approximately constant ratios in traverses through skeletal walls of a single mineralogy (either calcite or aragonite). Skeletal walls of more than one mineralogy have the magnesium-rich layer (calcite) surrounding the living chamber and the strontium-rich layer (aragonite) on the outside. In contrast, phosphorus may be present in greater or lesser amounts in different parts of the same calcite skeletal wall. Aragonitic crystallites appear oriented roughly perpendicular to skeletal walls, whereas calcitic crystallites are parallel to skeletal walls.

Animals↗

PubMed1987

Strontium phosphate transfection of human cells in primary culture: stable expression of the simian virus 40 large-T-antigen gene in primary human bronchial epithelial cells.

Strontium ion formed DNA-phosphate precipitates analogous to those formed by calcium but lacking the lethal and differentiation-inducing effects of calcium on many epithelial cell types in primary culture. Human primary bronchial epithelial cells were transiently and stably transfected by using strontium phosphate; the frequency of stable transformation with a plasmid carrying the simian virus 40 large-T-antigen gene was greater than 10(-4).

Antigens, Viral, Tumor↗

PubMed1990

Cerebrospinal fluid content of manganese, platinum, and strontium in patients with cerebral tumors, leukemia, and other noncerebral neoplasms.

Electrothermal atomic absorption spectrophotometry was employed to measure the concentrations of manganese, platinum, and strontium in the cerebrospinal fluid (CSF) of 47 patients with brain neoplasms (34 benign and 13 malignant), 17 leukemic patients, 10 patients with lymphoma or non-cerebral solid tumors, and 27 control patients. According to the data obtained, manganese appears to be significantly (p less than 0.015) depleted from the CSF of leukemic patients, whereas platinum is diminished in CSF of patients with brain tumors, leukemia, lymphoma, or noncerebral solid tumors; the ratios for the mean CSF concentration of platinum in these tumor patients/control patients ranged between 0.52 and 0.7. There was no significant difference in CSF concentrations of strontium among the groups examined.

Adolescent↗

PubMed1990

Effect of a strontium complex on fluoride uptake by artificial caries lesions and sound enamel in vitro.

The effect of a strontium-polyacrylate complex on fluoride uptake by bovine enamel was determined. A salivary pellicle was formed on sound enamel and enamel with artificially formed caries lesions. Ten specimens of each were treated with solutions containing (A) 225 ppm F, (B) 225 ppm F plus Sr complex, (C) 200 ppm F, 0.1 M phosphate, pH 4.5 or (D) placebo for 1 h and then washed 24 h to remove labile fluoride. Analysis of ten thin layers of enamel showed that, on both enamel types, solution (C) deposited the largest amount of fluoride. The strontium complex decreased fluoride deposition, particularly in the outermost layer.

Acidulated Phosphate Fluoride↗

PubMed1983

Acid reactivity of carbonated apatites with strontium and fluoride substitutions.

Carbonated apatites containing approximately 3.0 or 6.5% CO3 were precipitated in the presence of sodium, strontium, and/or fluoride at various concentrations. Almost all the available strontium and fluoride was incorporated into the crystals, whereas only a portion of the carbonate and sodium present was taken up. When incorporated together, Sr and F improved the crystallinity of carbonated apatites and markedly reduced their acid reactivity. This phenomenon may partially explain the observed reduction in caries for populations whose drinking water contains optimum levels of Sr at 5-10 mg/l and F at 1-2 mg/l.

Apatites↗

PubMed1989

Serum strontium estimation as a medico-legal diagnostic indicator of drowning.

In order to corroborate the medico-legal diagnosis of vital submersion we reviewed the appropriate literature and tested Icard's initial hypothesis, already expressed in 1932, that Strontium might be a good indicator of sea-water drowning. Therefore, we examined all the bodies found either in fresh or in sea-water, and also non-drowned control cases. Strontium concentrations in both cardiac cavities and in a peripheral blood-vessel were determined by flameless atomic absorption spectrophotometry. The statistical evaluation of the results is hereby presented. We come to the conclusion that this determination can be a valuable additional proof for sea-water drowning diagnosis, whilst freshwater drowning would be more difficult to assess. Further investigations are being undertaken.

Drowning↗