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Sequential isotopic determination of plutonium, thorium, americium, strontium and uranium in environmental and bioassay samples.

A procedure has been developed to provide sequential analysis of 238Pu, 230Th, 241Am, 238U, and 90Sr in environmental and bioassay samples. Tracers and/or carriers (242Pu, 243Am, 232U, and stable strontium) are added into the sample as chemical yield monitors, and then, plutonium, thorium, strontium, americium, and uranium are sequentially separated and purified by Dowex ion-exchange resin, EiChroM Sr-resin, EiChroM TRU-resin, and Chelate-100 resin, respectively. The radioactivities of 90Sr and the actinides are measured using the liquid scintillation counter and alpha-particle spectrometer, respectively. Acidified water, glass-fiber air filter, soil, synthetic urine and synthetic feces samples of US National Institute of Standard and Technology Radiochemical Intercomparison Program(NRIP) were analyzed to verify this method. All the analytical results of 238Pu, 230Th, 90Sr, 241Am and 238U meet the traceability limit per ANSI N42.22, and when appropriate, evaluation of radiobioassay measurement bias and precision per ANSI N13.30.

Chromatography, Ion Exchange↗

PubMed2005

Sorption kinetics of strontium in porous hydrous ferric oxide aggregates II. Comparison of experimental results and model predictions.

In a previous paper, we introduced the Donnan diffusion model to describe cation diffusion into microporous solids with variably charged surfaces, such as hydrous ferric oxides (HFO). Here, we present experiments investigating slow diffusion and sorption of strontium by HFO aggregates with well-characterized porosity. Adsorption of protons and strontium at the HFO surface was evaluated by acid-base titration and batch adsorption experiments with dispersed HFO. The experimental data were fitted with a 1-pK basic Stern model including surface ion pair formation of Na(+) and NO(3)(-) and charge distribution for Sr surface complexes. Sorption-diffusion experiments were conducted in flow-through columns at controlled flow rates and at two different pH values, pH 4 and 7. Wet HFO aggregates, which were synthesized using a freezing and thawing method, were packed into chromatographic columns, pre-equilibrated to reach a constant pH, and then Sr breakthrough curves for adsorption and desorption of Sr were recorded. Strong retardation of Sr indicated that diffusion was sufficiently fast in a fraction of pores, so that sorption sites in these pores were rapidly accessible. Based on the analysis of NaNO(3) breakthrough curves, this rapidly accessible pore fraction was estimated to be 37% of the total aggregate pore volume at pH 4.0 and 72% at pH 7.0, respectively. Taking this into account, the Donnan diffusion model gave a good description of the experimental Sr breakthrough curves. Cation exclusion was correctly predicted at pH 4.0. At pH 7, the strong tailing of Sr breakthrough curves due to Sr diffusion into the smallest pores was very well simulated. The Donnan diffusion model proved adequate for pore sizes between approximately 2 and 5 nm, depending on pH and ionic strength. This category of pores was dominant in the HFO aggregates used in this work.

Journal Article↗

PubMed2005

Synthesis and growth mechanisms of one-dimensional strontium hydroxyapatite nanostructures.

Strontium hydroxyapatite (SrHAp) nanowires with an aspect ratio of several hundreds were synthesized by controlling the growth conditions during a hydrothermal process. In the strontium phosphate system, it was found that the phase evolution changed with pH and that the aspect ratio of SrHAp was affected by the phases present before heating. Since the conditions for SrHAp nucleation prohibits one-dimensional growth, it was impossible to grow large-scale SrHAp nanowires using routine hydrothermal methods. Through thermodynamic considerations, the mechanisms of nanowire formation appear to involve the rapid release of the stored chemical potential in a metastable phase, which promotes the anisotropic growth of the most stable SrHAp nanostructures. Thereby, the conditions for both the nucleation of the SrHAp phase and the anisotropic growth were determined simultaneously, and considerable quantities of SrHAp nanowires were synthesized.

Journal Article↗

PubMed2001

A study of heat-treatment induced framework contraction in strontium-ETS-4 by powder neutron diffraction and vibrational spectroscopy.

The effects of heat-treatment on the structure of the strontium ion-exchanged titanosilicate ETS-4 have been studied by Rietveld analysis of powder neutron diffraction data and by FT-Raman spectroscopy. Hydrous Sr-ETS-4 (space group Cmmm), upon heat-treatment under inert atmosphere at temperatures between 423 and 573 K, exhibits framework contraction as evinced by the decrease in the unit cell dimensions. The effects of heat-treatment on the dimensions of the transport-controlling eight-membered ring (8MR) are elucidated by Rietveld analysis. It is also found that during heat-treatment: (a) the double three membered rings (D3MRs) in ETS-4 are sites of structural instability, (b) the titania chains running along [010] exhibit a large degree of disorder in the bridging oxygen atoms, and (c) significant relocations of the strontium cations take place, which may affect the separation properties of the heat-treated materials. Raman spectra of heat-treated ETS-4 crystals exhibit strong cation-framework interaction effects. Vibrational modes involving the atoms in the titania chains show progressive frequency shifts and loss of intensity with increasing heat-treatment temperature, in a manner consistent with the crystallographic results. The study indicates the potential for continuously varying the effective pore dimension of ETS-4 by combining heat-treatment with appropriate ion-exchange procedures.

Journal Article↗

PubMed2002

In vivo response of strontium and zinc-based ionomeric cement implants in bone.

In this study the osteoconductive properties of strontium based ionomeric cements (ICs) named, LG125 and LG119, as well as zinc-based ICs, designated by LG130 and LG132, were compared. Wet ICs were surgically implanted into the femora of weaned Wistar rats for 4 weeks. To assess the percentage osseointegration the perimeter of the implant and the perimeter of bone in contact with the implant were measured using a pointer (the length of bone/implant interfacial contact). Osteoconduction was determined by taking six points at random around the perimeter of each ionomeric rod measuring the thickness of newly formed bone. The degree of osteoconduction was taken as the average thickness of new bone produced on the implant surface. It was found that osteoconduction was greatest in the strontium based IC implant LG125. From these studies it can be concluded that the composition LG125 might provide a useful purpose as a bone cement.

Journal Article↗

PubMed2002

Coherent light transport in a cold strontium cloud.

We study light coherent transport in the weak localization regime using magneto-optically cooled strontium atoms. The coherent backscattering cone is measured in the four polarization channels using light resonant with a J(g) = 0-->J(e) = 1 transition of the strontium atom. We find an enhancement factor close to 2 in the helicity preserving channel, in agreement with theoretical predictions. This observation confirms the effect of internal structure as the key mechanism for the contrast reduction observed with a rubidium cold cloud [G. Labeyrie et al., Phys. Rev. Lett. 83, 5266 (1999)]. Experimental results are in good agreement with Monte Carlo simulations taking into account geometry effects.

Journal Article↗

PubMed2006

Structure of strontium barium niobate SrxBa1-xNb2O6 (SBN) in the composition range 0.32<or=x<or=0.82.

The structure of strontium barium niobate crystals SrxBa1-xNb2O6 is comprehensively studied in the whole range of the tetragonal tungsten bronze phase (x=0.32-0.82) using both powder and single-crystal X-ray diffraction measurements. Unit-cell parameters, density, site-occupancy factors and interionic distances show an explicit composition dependence which can be consistently explained using simple model calculations. The temperature dependence of the unit-cell parameters exhibits a remarkable anisotropy in a broad temperature region below the phase transition temperature. This proves that the electrostrictive contribution to the thermal expansion plays an important role in strontium barium niobate.

Journal Article↗

PubMed2002

Strontium ranelate: dose-dependent effects in established postmenopausal vertebral osteoporosis--a 2-year randomized placebo controlled trial.

The aim of the strontium ranelate (SR) for treatment of osteoporosis (STRATOS) trial was to investigate the efficacy and safety of different doses of SR, a novel agent in the treatment of postmenopausal osteoporosis. A randomized, multicenter, double-blind, placebo-controlled trial was undertaken in 353 osteoporotic women with at least one previous vertebral fracture and a lumbar T-score <-2.4. Patients were randomized to receive placebo, 0.5 g, 1 g, or 2 g SR/d for 2 yr. The primary efficacy endpoint was lumbar bone mineral density (BMD), assessed by dual-energy x-ray absorptiometry. Secondary outcome measures included femoral BMD, incidence of new vertebral deformities, and biochemical markers of bone metabolism. Lumbar BMD, adjusted for bone strontium content, increased in a dose-dependent manner in the intention-to-treat population: mean annual slope increased from 1.4% with 0.5 g/d SR to 3.0% with 2 g/d SR, which was significantly higher than placebo (P < 0.01). There was a significant reduction in the number of patients experiencing new vertebral deformities in the second year of treatment with 2 g/d SR [relative risk 0.56; 95% confidence interval (0.35; 0.89)]. In the 2 g/d group, there was a significant increase in serum levels of bone alkaline phosphatase, whereas urinary excretion of cross-linked N-telopeptide, a marker of bone resorption, was lower with SR than with placebo. All tested doses were well tolerated; the 2 g/d dose was considered to offer the best combination of efficacy and safety. In conclusion, SR therapy increased vertebral BMD and reduced the incidence of vertebral fractures.

Aged↗

PubMed2004

Detailed study of an efficient blue laser source by second-harmonic generation in a semimonolithic cavity for the cooling of strontium atoms.

We have constructed a blue laser source consisting of an amplified, grating tuned diode laser that is frequency doubled by a KNbO3 crystal in a compact standing wave cavity and produces as much as 200 mW of internal second-harmonic power. We have analyzed the unusual characteristics of this standing wave cavity to clarify the advantages and disadvantages of this configuration as an alternative to a ring cavity for second-harmonic generation. We emphasize its efficiency and stability and the fact that it has an inherent walk-off compensation, similar to twin crystal configurations. We demonstrate its utility for laser cooling and trapping of earth alkalis by stabilizing the laser to the 461-nm transition of strontium, using a heat pipe, and then forming a magneto-optic trap of strontium from a Zeeman-slowed atomic beam.

Journal Article↗

PubMed2005

Strontium ranelate (Fujisawa/Servier).

Strontium ranelate (PROTELOS), a divalent strontium salt, has been developed and launched by Servier for the treatment of osteoporosis. Fujisawa Pharmaceutical is developing the drug in Japan; in November 2004, phase II Japanese trials were ongoing.

Animals↗

PubMed2005

[Strontium ranelate: a new therapeutic principle for postmenopausal osteoporosis].

Strontium ranelate (SR) is a new drug for osteoporosis that has a unique effect profile, being antiresorptive as well as anabolic. In postmenopausal women with spinal osteoporosis pretreated with calcium and vitamin D, SR reduced the risk of new vertebral fractures after 1 year by 49% and after 3 years by 41% (NNT = 9). The numbers of clinical fractures were in the same periods reduced by 52% and 38%, respectively. The number of patients with more than one new spinal fracture was reduced by 36%. Height reduction was less among the patients so treated, and there was a tendency towards less lumbar pain. Measured lumbar BMD increased 14.4% over three years, corresponding to an increase of 6.8% after adjustment for bone strontium content, compared with a decrease in the placebo group of 1.3%. The risk of new non-vertebral fractures was reduced by 16%. Among elderly women with a hip T-score <-3, SR decreased the risk of hip fractures by 36% over three years (NNT = 48). In patients with osteopenia and at least one clinical risk factor, SR reduced the risk of first vertebral fracture by 72% over three years (NNT = 12). In patients over 80 years of age, the risk of new vertebral fractures was reduced by 32% (NNT = 14). There were few side effects. SR is thus suitable for reducing the risk of vertebral and hip fractures from postmenopausal osteoporosis, especially among patients with upper abdominal dyspepsia and the elderly.

Aged↗

PubMed2006

Strontium ranelate for osteoporosis?

In the UK, there are around 200,000 osteoporotic fractures each year. National guidelines in the UK recommend preventative treatment in patients who are at high risk of fracture on the basis of age, fracture history, bone mineral density and other risk factors. For secondary prevention, an oral bisphosphonate, such as alendronate or risedronate, is the drug of choice but may not be tolerated, particularly because of unwanted upper gastrointestinal effects. Raloxifene provides a potential oral alternative in women. National guidelines also suggest subcutaneous teriparatide for women aged more than 65 years with severe osteoporosis who have failed to tolerate or respond to a bisphosphonate; however, we believe use of this drug is problematic. Strontium ranelate (Protelos-Servier) is a new oral treatment for women with postmenopausal osteoporosis that is promoted as "the first dual action bone agent" and "the only drug to simultaneously increase bone formation and decrease bone resorption". Here we review the evidence for strontium ranelate and consider whether it has a role in postmenopausal osteoporosis.

Aged↗

PubMed2006

[Synthesis and spectral properties of a new europium strontium oxide SrEu2O4].

A new europium strontium oxide was synthesized by high-temperature solid state reaction of SrCO3 with Eu2O3 in air. The new multiple oxide was characterized by use of XRD, TG/DTA and fluorescence spectra. The XRD results show that the molecular formula of the europium strontium oxide is SrEu2O4, whose structure is isostructural with that of BaEu2O4 reported earlier. The excitation spectrum of SrEu2O4 displays a broad double peaks band with one peak around 257 nm and the other around 280 nm. This broad band is attributed to the charge transfer transition of Eu3+-O2- bonds. Excited with a radiation of 280 nm, SrEu2O4 emits strong red light which is assigned to the 5D0-->7F2 electric dipole transition of Eu3+.

English Abstract↗

PubMed2007

[Therapeutic agents for disorders of bone and calcium metabolism. Osteoporotic fracture prevention by strontium ranelate].

Bone loss results in osteoporosis and increased susceptibility to bone fractures. Importantly, osteoporosis is a major cause of morbidity and mortality in the elderly population. With a constantly increasing aging population worldwide, early prevention of bone loss is essential for adequate control of this condition. Strontium ranelate, an oral treatment for postmenopausal osteoporosis, is unique in its mode of action as it is the sole anti-osteoporotic agent that both decreases bone resorption and increases bone formation. Its efficacy to reduce vertebral and non-vertebral fractures including those of the hip, in addition to its safety profile has been demonstrated in the Spinal Osteoporosis Therapeutic Intervention (SOTI) and Treatment of Peripheral Osteoporosis (TROPOS) clinical studies over 3 years and recently confirmed over the long-term. Furthermore, a pre-planned analysis of a sub-group of patients aged 80 years and over demonstrated that, currently, strontium ranelate is the only anti-osteoporotic agent to reduce vertebral and non-vertebral fractures in this age group.

Administration, Oral↗

PubMed1965

STUDIES OF INHIBITION OF INTESTINAL ABSORPTION OF RADIOACTIVE STRONTIUM. IV. ESTIMATION OF THE SUPPRESSANT EFFECT OF SODIUM ALGINATE.

A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, allowing calcium to be available to the body. Studies were carried out on the inhibitory effect of various amounts of sodium alginate and the dose-response relationship of Sr(89) and bone uptake. The results obtained indicated that under laboratory conditions sodium alginate effectively reduces Sr(89) uptake in a constant proportion. This effect was observed at the three levels of administration of 1.4%, 12% and 24% of sodium alginate. The linear relationship between the dosage of the radioisotope and the bone uptake in the presence of sodium alginate suggests that the same proportion is maintained at the lower levels of intake of radioactive strontium.Previous studies with small constant doses of sodium alginate were extended in rats to a period corresponding approximately to three years of human life span. Low doses were sufficient to reduce appreciably bone uptake of radiostrontium.

Alginates↗

PubMed2000

Treatment of bone metastases of prostate cancer with strontium-89 chloride: efficacy in relation to the degree of bone involvement.

This retrospective study evaluated the toxicity and efficacy of strontium-89 chloride (Metastron, Amersham) in 94 patients with painful bone metastases of prostate cancer (117 injections of 150 MBq) and compared the efficacy of treatment in patients with moderate and extensive bone involvement. The predictive value of flare response with regard to analgesic response was also studied. High-grade leukothrombopenias were observed after only 5% of injections. An improvement in quality of life was obtained in 65% of cases, a decrease in pain in 78% (31% complete response) and a reduction of analgesics in 60%. Efficacy was significantly better for pain decrease (P=0.005) and reduction of analgesics (P=0.018), and response was significantly longer (P<0.0035) in patients with moderate than in patients with extensive bone involvement. The flare response observed in 23% of cases was not predictive of pain response (P=0.919) or reduction of analgesics (P=0.353). A second dose prolonged analgesia in three-quarters of cases without any apparent increase in toxicity. These results confirm the benefit of 89Sr chloride for the treatment of metastatic bone pain and suggest that internal radiotherapy should be started earlier. A bone scan could be proposed at the time of hormonal escape resulting in bone pain, and internal radiotherapy could be initiated when several metastatic foci exist, even if only one is painful. In this way, pain-free follow-up could be prolonged, and the transition to other therapeutic approaches, particularly opioids, delayed.

Aged↗

PubMed1997

Strontium-89 for palliation of pain from bone metastases in patients with prostate and breast cancer.

We have used strontium-89 chloride (89Sr) for the palliative treatment of metastatic bone pain. Seventy-six patients (50 males with prostate carcinoma and 26 females with breast cancer) were treated with 148 MBq of 89Sr. Sixteen patients were retreated, receiving two or three doses; the total number of injected doses was consequently 95. The Karnofsky performance status was assessed and pain and analgesia were scored on scales of 9 and 5 points, respectively. The efficacy of 89Sr was evaluated at 3 months of treatment. Three levels of response were considered: good - when there was an increase in the Karnofsky status and a decrease in the pain score (equal to or higher than 4) or analgesic score (equal to or higher than 1); partial - when there was an increase in the Karnofsky status and a decrease in the pain score (2 or 3 points) without significant changes in the analgesic score; no response - if no variation or deterioration in these parameters was observed. In prostate cancer patients, the response was good in 64% of cases and partial in 25%, and there was no response in the remaining 11%. In breast cancer patients, the response was good in 62% of cases and partial in 31%, and there was no response in the remaining 8%. Duration of the response ranged from 3 to 12 months (mean 6 months). In the patients who were retreated the effectiveness was as good as after the first dose of 89Sr. A decrease in the initial leucocyte and platelet counts was observed after the 1st month of treatment, with a gradual partial to complete recovery within 6 months. It is concluded that 89Sr is an effective agent in palliative therapy for metastatic bone pain in patients with prostate or breast carcinoma. If required, retreatment can be administered safely and with the same efficacy as is achieved by the first dose.

Aged↗

PubMed2006

Human biokinetics of strontium. Part I: intestinal absorption rate and its impact on the dose coefficient of 90Sr after ingestion.

Intestinal absorption of strontium (Sr) in thirteen healthy adult German volunteers has been investigated by simultaneous oral and intravenous administration of two stable tracer isotopes, i.e. (84)Sr and (86)Sr. The measured Sr tracer concentration in plasma was analyzed using the convolution integral technique to obtain the intestinal absorption rate. The results showed that the Sr labeled in different foodstuffs was absorbed into the body fluids in a large range of difference. The maximum Sr absorption rates were observed within 60-120 min after administration. The rate of absorption is used to evaluate the intestinal absorption fraction, i.e. the f (1) value for various foodstuffs. The equivalent and effective dose coefficients for ingestion of (90)Sr were calculated using these f (1) values, and they were compared with those recommended by the International Commission on Radiological Protection (ICRP). The geometric and arithmetic means of the f (1) values are 0.38 and 0.45 associated with a geometric standard deviation and a standard deviation of 1.88 and 0.22, respectively. The 90% confidence interval of the f (1) values obtained in the present study ranges from 0.13 to 0.98. Expressed as the ratio of the 95 and 50% percentiles of the estimated probability, the uncertainty for the f (1) value corresponds to a factor of 2.58. The effective dose coefficients of (90)Sr after ingestion are 6.1 x 10(-9) Sv Bq(-1) for an f(1) value of 0.05, 1.0 x 10(-8) Sv Bq(-1) for 0.1, 1.9 x 10(-8) Sv Bq(-1) for 0.2, 2.8 x 10(-8) Sv Bq(-1) for 0.3, 3.6 x 10(-8) Sv Bq(-1) for 0.4, 5.3 x 10(-8) Sv Bq(-1) for 0.6, 7.1 x 10(-8) Sv Bq(-1) for 0.8, and 7.9 x 10(-8) Sv Bq(-1) for 0.9, respectively. Taking the effective dose coefficient of 2.8 x 10(-8) Sv Bq(-1) for an f (1) value of 0.3, which is recommended by the ICRP, as a reference, the effective dose coefficient of (90)Sr after ingestion varies by a factor of 2.8 when the f (1) value changes by a factor of 3, i.e. it decreases from 0.3 to 0.1 or increases from 0.3 to 0.9, respectively.

Administration, Oral↗