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The determination of strontium in human blood samples by ICP-AES is described. For the analysis no chemical separations were required after microwave destruction. A mean value of 11.4 +/- 0.83 micrograms/l is found for normal whole blood. The limit of detection of the method is 0.3 microgram/l. As a possible application the enhancement of the strontium level in blood of human beings who died from drowning is examined.
The induction of strontium overload and its electromechanical manifestations, the factors influencing and the mechanism underlying Sr overload were studied in Purkinje fibers perfused in vitro. Strontium: (1) can induce an oscillatory potential (Vos) and repetitive spontaneous activity at low concentrations (1.35-2.7 mM); (2) at high concentrations (5.4-10.8 mM) less frequently causes a Vos but during recovery in Tyrode solution Vos appears as Sr overload recedes; (3) decreases the maximum diastolic potential by inducing a prolonged depolarization (Vex) which subsides slowly during an interruption of drive; (4) induces a larger Vex after procedures that increase Sr loading (fast driving rates, higher [Sr]o or longer action potentials); (5) does not induce Vos and Vex when the slow channel is blocked; (6) exaggerates Vex (but not Vos) in calcium overloaded fibers; (7) exchanges with Na since in low [Na]o the twitch amplitude increases; (8) is removed from the cell at the resting potential since after a period of quiescence the first resumed twitch decreases as a function of the preceding pause duration; (9) needs Na as charge carrier since the slope of diastolic depolarization decreases in low [Na]o. Thus, Sr causes overload even at low concentrations and induces an oscillatory potential and the prolonged depolarization Vex, whose mechanism appears to be an electrogenic Sr extrusion through Na-Sr exchange.
Twenty-seven patients with malignant epithelial tumors of the conjunctiva were treated between 1967 and 1987. Histological diagnosis was intraepithelial epithelioma in 15 cases (56%) and squamous cell carcinoma in 12 (44%). All patients were treated with a strontium-90 source on cup-shaped applicators of different sizes according to the extension of the tumor. Surface dose ranged from 60 Gy in a single treatment to 140 Gy in 7 fractions, depending on the thickness of the lesion. Fifteen patients were previously untreated, 7 were irradiated after some type of surgical treatment and 5 were treated for recurrence after multiple surgical excisions. Follow-up period ranged from 2 to 15 years. No patient died of his tumor. There were four local recurrences, three of them in patients with intraepithelial carcinoma. Two of the recurrences were salvaged with a new beta-ray treatment and the other two with enucleation. Since 1981, standard policy was to irradiate the entire conjunctiva in patients with diagnosis of intraepithelial epithelioma. Five patients developed cataracts. Considering the high primary control rate and minimal morbidity, strontium irradiation should be considered as a first-choice treatment for conjunctival tumors.
The results of a pilot investigation are presented. The study aimed to show that the presence of radioactive strontium-90 in human bone could be used as evidence of active uptake during life. In this way the time since death of the individual could be identified as occurring before or after the date when atmospheric levels of radioactive strontium were at a peak in the early 1960s. The results of this initial investigation were encouraging but further detailed analysis is required on a substantially larger sample of material spanning a more controlled time period.
The concentration of 38 trace and bulk elements in the serum from 19 patients with recent onset of epilepsy and 20 age- and sex-matched controls was estimated by neutron activation analysis or inductively coupled plasma source by mass spectrometry. The concentrations of aluminium, strontium and zinc were significantly higher and the concentrations of cobalt and manganese were significantly lower than controls. Low concentrations of manganese and high concentrations of zinc in epilepsy have been previously reported but the abnormalities of aluminium, cobalt and strontium are new findings. The possible significance of these results in the pathogenesis of epilepsy is discussed.
A new route was developed to synthesis a new type of strontium-containing hydroxyapatite (Sr-HAP) bone cement with precursors of tetracalcium phosphate (TTCP), strontium hydrogen phosphate (DSPA), dicalcium phosphate (DCPA), phosphate acid and water. The processing parameters and fundamental properties including pH value, setting time, compressive strength of final hardened body and the cytotoxicity for serial extracts of each cements were investigated. The result shows that the final product of the cement after setting for 24h is nonstoichiometic Sr-containing hydroxyapatite (Ca(10-m-x)Sr(x) square(m)(HPO4)y(PO4)6-y(OH)2-2m square2m, 0<x<1, nSr-HAP) and no other harmful impurities were detected. The pH value of Sr-containing cement pastes approaches to 7.0-7.6 when they are mixed with a ratio of 1:1 of powder to liquid (P/L) in weight. The setting time of the cement pastes is 4-11 min for the initial one and 10-17 min for the final one when the concentration of diluted phosphate is in a range of 0.5-1.0 mol/l. The compressive strengths of the hardened cements with different molar ratios of Sr/(Sr+Ca) after subjected an immersion in simulated body fluid (SBF) increase uniformly from 1 day to 5 days, where they get maximum values, respectively, but then decrease till to 2 weeks. Especially for the CPC-1, with a Sr/(Sr+Ca) molar ratios of 5% in cement powder composition, the largest compressive strength gained at 5 days is 66.57 MPa and the lowest one gained at 2 weeks is 44.75 MPa, which matches the value of human bones and can be expected to use in clinic application in repairing the nonloading sites on account of the positive result of cytotoxicity test of the extracts of Sr-containing calcium phosphate cement (Sr-CPC).
The bone-bonding behaviors of various biomaterials have been extensively investigated. However, the precise mechanisms of bone bonding have not yet been clarified, and the differences in interfacial behaviors of biomaterial bonding with cancellous bone and cortical bone have not yet been understood. In this study, strontium-containing hydroxyapatite (Sr-HA) cement, in which 10% calcium ions were substituted by strontium, was performed in a rabbit hip replacement model. Six months later, the morphology and chemical composition of interfaces between Sr-HA cement with cancellous bone and cortical bone were evaluated by field emission scanning electron microscopy (FESEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Remarkable differences between these two interfaces were suggested both in morphology and chemical compositions. An apatite layer was found between Sr-HA cement and cancellous bone with a thickness of about 70 microm. However, only a very thin interface (about 1 microm) was formed with cortical bone. As for the cancellous bone/cement interface, high ions intensity of Ca, P, Sr, Na, and O were confirmed by FESEM-EDX and ToF-SIMS. Differences in morphology and chemical component between these two interfaces provided convincing evidences for the proposed dissolution-precipitation coupling mechanism in the formation of biological apatite.
Recently, strontium (Sr) as ranelate compound has become increasingly popular in the treatment of osteoporosis. However, the lattice structure of bone crystal after Sr incorporation is yet to be extensively reported. In this study, we synthesized strontium-substituted hydroxyapatite (Sr-HA) with different Sr content (0.3%, 1.5% and 15% Sr-HA in mole ratio) to simulate bone crystals incorporated with Sr. The changes in chemical composition and lattice structure of apetite after synthetic incorporation of Sr were evaluated to gain insight into bone crystal changes after incorporation of Sr. X-ray diffraction (XRD) patterns revealed that 0.3% and 1.5% Sr-HA exhibited single phase spectrum, which was similar to that of HA. However, 15% Sr-HA induced the incorporation of HPO4(2-) and more CO3(2-), the crystallinity reduced dramatically. Transmission electron microscopy (TEM) images showed that the crystal length and width of 0.3% and 1.5% Sr-HA increased slightly. Meanwhile, the length and width distribution were broadened and the aspect ratio decreased from 10.68+/-4.00 to 7.28+/-2.80. The crystal size and crystallinity of 15% Sr-HA dropped rapidly, which may suggest that the fundamental crystal structure is changed. The findings from this work indicate that current clinical dosage which usually results in Sr incorporation of below 1.5% may not change chemical composition and lattice structure of bone, while it will broaden the bone crystal size distribution and strengthen the bone.
Mucilaginous seeds of Ocimum basilicum were used in uptake studies with cesium-137 and strontium-90. Results showed that uptake was dependent on the structural integrity of the mucilage fibrils. Water imbibed seeds showed higher adsorption of both 137Cs and 90Sr in comparison to seeds pretreated with NaOH, HCl and Na-periodate solution. The uptake was pH dependent and while some divalent metal ions had no or little detrimental effect, the alkali metal ions Li+, Na+ and K+ decreased the uptake. The maximum adsorption capacity was 160 mg cesium g(-1) and 247 mg strontium g(-1) seed dry weight.
Radium is one of the prominent potential contaminants linked with industries extracting or processing material containing naturally occurring radionuclides. In this study we investigate if 133Ba and 85Sr can be used as tracers for predicting 226Ra soil-to-plant transfer. Three soil types were artificially contaminated with these radionuclides and transfer to ryegrass and clover was studied. Barium is considered a better tracer for radium than strontium, given the significant linear correlation found between the Ra and Ba-TF. For strontium, no such correlation was found. The relationship between soil characteristics and transfer factors was investigated. Cation exchange capacity, exchangeable Ca+Mg content and soil pH did not seem to influence Ra, Ba or Sr uptake in any clear way. A significant relation (negative power function) was found between the bivalent (Ca+Mg) concentration in the soil solution and the Ra-TF. A similar dependency was found for the Sr and Ba-TF, although less significant.
There is growing evidence that strontium ranelate (SR; S12911-2, PROTELOS; Institut de Recherches Internationales Servier, Courbevoie, France), a compound containing 2 atoms of stable strontium (Sr), influences bone cells and bone metabolism in vitro and in vivo. We previously reported that SR increases bone mass in rats and mice by stimulating bone formation and inhibiting bone resorption. We also showed that short-term treatment with SR enhances osteoblastic cell recruitment and function in short-term rat calvaria cultures. Because Sr incorporates into the bone matrix, it was of interest to determine whether SR may affect matrix mineralization in long-term culture. To this goal, osteogenic mouse calvaria-derived MC3T3-E1 osteoblastic cells were cultured for up to 14 days in the presence of ascorbic acid and phosphate to induce matrix formation and mineralization. Matrix formation was determined by incorporation of tritiated proline during collagen synthesis. Matrix mineralization was quantified by measuring the number and surface of mineralized nodules using a digital image analyzer. In this model, 1,25(OH)2 vitamin D (1 nmol/L) used as internal control, increased alkaline phosphatase (ALP) activity, an early osteoblast marker, on days 4, 10, and 14 of culture. Treatment with SR (1 mmol/L Sr(2+)) increased ALP activity at days 4 and 14 of culture. SR also increased collagen synthesis at days 4 and 10 of culture. In contrast, 1,25(OH)2 vitamin D (1 nmol/L) inhibited collagen synthesis at 4 to 14 days of culture. Long-term treatment with SR (0.1 to 1 mmol/L Sr(2+)) dose dependently increased Sr concentration into the calcified nodules, but did not alter matrix mineralization in long-term culture, as shown by the ratio of the surface of mineralized nodules to the number of mineralized nodules on day 14 of culture. These results show that long-term treatment with SR increases collagenous matrix formation by MC3T3-E1 osteoblasts without inducing deleterious effect on matrix mineralization.
OBJECTIVES: In a prospective randomized Canadian trial, addition of radionuclide strontium (89Sr) to external radiotherapy (ER) was found to prolong the time to further ER by 15 weeks (35 versus 20, P = 0.006) compared to ER alone in patients with hormone-refractory metastatic prostate cancer (HRMPC). The total direct lifetime costs within the Swedish health care system for the following two treatment strategies was estimated as follows: (a) ER initially and in the event of relapse and (b) ER + 89Sr initially and ER in the event of relapse. METHODS: Calculation of lifetime costs was based on the initial total treatment cost and the probability of future treatment costs. In a retrospective analysis, the average cost of a relapse treated with ER alone was calculated from the actual care consumption of 79 consecutive patients from the south of Sweden who received ER because of skeletal pain due to HRMPC. The costs related to ER included skeletal scintigraphy, ER, outpatient visits, inpatients days, and travel to the treatment center. When 89Sr was added, the cost also included the radionuclide and its administration. Costs in Swedish currency (SEK) were based on the regional tariff for 1993 (U.S. $1 = SEK 8.30). RESULTS: The initial cost for one relapse treated with ER alone was estimated to be SEK 31,011 (U.S. $3736) per patient resident within county (close to hospital) and SEK 48,585 (U.S. $5854) per patient resident out of county (far from hospital). The corresponding figure for initial addition of 89Sr to ER was SEK 43,426 (U.S. $5232) and 61,000 (U.S. $7349), respectively. However, comparison between estimated lifetime cost for the two treatment strategies indicated potential cost savings with initial addition of 89Sr to 3% SEK 2720 (U.S. $328) and 7% SEK 11,290 (U.S. $1360), respectively. CONCLUSIONS: Strontium-89 as initial supplement to ER for palliation of pain in HRMPC is beneficial both from the patient and lifetime health service costs perspectives.
This work deals essentially with the study of the interactions between chitosan and an alkaline-earth metal: 85Sr. We showed that addition of carbonate ions is necessary to observe this interaction, but only for pH values over 11. The use of an appropriate calculation software allowed us to determine the nature of the strontium ionic species present in solution. In order to understand the mechanism of interaction, the influence of various parameters on the complexation was studied. Thus, the interaction was maximum for a CO3(2-) concentration close to 10(-2) mol/l, the lowest ionic strength, the most expanded physical form (lyophilisate) and the lowest degree of acetylation of the polymer. We conclude to the formation of a ternary complex between the ion pair Sr2+ CO3(2-) and the amino groups of chitosan. We also showed the presence of interactions between chitosan and carbonate ions which hinder further interactions with strontium ions.
Vegetation-to-milk transfer coefficients for 137Cs, 90Sr and stable strontium were determined for cows grazing on two intensively managed lowland pastures and two Alpine pastures in Austria. The 90Sr transfer coefficient at the four pastures ranged from 0.0005 to 0.0012 dl-1 and correlated with the stable strontium transfer coefficient (0.0006-0.0013 dl-1) with the lower values found on the intensively managed pastures. The 137Cs transfer coefficient ranged from 0.0009-0.0045 dl-1.
An analytical technique utilizing selective extractant resins to concentrate strontium and actinides from soil followed by separation with radiochromatography was evaluated. The technique was tested using uncontaminated soil samples spiked with a radionuclide tracer solution that were either microwave-aided acid digested or leached with a strong acid. Extraction of the strontium and actinides from the acidified solution was accomplished using a serial arrangement of Sr-Resin and TRU-Resin columns. The combined eluate solutions from the extraction resins were treated with HNO(3) and H(2)O(2) to oxidize residual extractant and eluates prior to separation and analysis of the radionuclides by radiochromatography. Chromatograms obtained with larger soil mass loadings resulted in either incomplete peak resolution of the tracers or had highly variable peak elution times, indicative of an ionic interfering constituent(s). Better separations (e.g., chromatograms that resolved all radioactive constituents) were obtained when the sample mass loading was decreased, but with a concurrent decreased sensitivity for the radionuclides. Elemental analyses of the soil were conducted to provide data on the ionic constituents in unprocessed soil and post-processed soil samples. These results identified aluminum as an interfering contributor to the poor performance exhibited by the radiochromatographic separations.
OBJECTIVES: To compare toxicity, subjective response rate, time to subjective progression and overall survival in patients with painful bone metastases of hormone-resistant prostate cancer (HRPC) treated with a single intravenous injection of 150MBq (4mCi) Strontium(89) Chloride (S) or palliative local field radiotherapy (R) with the usual radiotherapy regimen used at each centre. The costs of both treatments were also assessed. PATIENTS AND METHODS: 101 patients were randomized to S and 102 to R. Time to event endpoints were compared with the Logrank test and Kaplan-Meier curves, in the intent-to-treat population (2-sided alpha=0.05). RESULTS: Baseline characteristics of both groups were comparable. There was a borderline statistically significant difference in overall survival in favour of the local field radiotherapy (R: 11 months; S: 7.2 months; p=0.0457). There was no difference in progression-free survival or time to progression. Subjective response was seen in 34.7% in the S-arm and in 33.3% in the R-arm. A biochemical response was observed in 10% and 13% of the R- and S-groups, respectively. There was no difference in treatment toxicity between the two groups. CONCLUSION: In symptomatic HRPC, pain treatment with local field radiotherapy is associated with a better overall survival compared to Strontium(89). The lower costs of local field radiotherapy also favour the use of this treatment in patients with HRPC. The reason for the apparent survival benefit of localised radiation treatment is not clear.
The presence of Sr in bone influences bone mineral density (BMD) and content (BMC) measurements by dual-energy X-ray absorptiometry (DXA). This interaction is of interest, since strontium ranelate (S12911) demonstrated positive effects on bone metabolism in various animal models of osteoporosis, and is currently being evaluated for treatment of postmenopausal osteoporosis. The present in vitro study aimed to determine adjustment factors for DXA measurements of BMC and BMD at different Sr concentrations in order to estimate the corresponding values that would have been measured without Sr. A series of mixtures of Ca and Sr hydroxyapatites were prepared, with biologically relevant Sr/Ca ratios ranging from 0 to 3.5 mol/mol%, and a constant total concentration of divalent cations (145 mmol). The mixtures were conditioned in plastic dishes 4.5 cm in diameter, to obtain an areal density close to the human vertebral mineral density of 0.7-1.1 g/cm(2). DXA measurements of the mixtures were made with a wide range of different instruments and various acquisition modes. A direct linear relationship (r(2) > 0.99) was found between strontium content and overestimation of BMD and BMC. There were no significant differences in adjustment factors for BMC or BMD between the different machines or acquisition modes, and the presence of Sr in the water bath used to mimic soft tissues did not affect the accuracy and precision of the method. This demonstrates that reliable DXA determinations of BMD may be carried out in the presence of Sr, and may be interpreted in terms of calcium hydroxyapatite equivalent if the bone Sr content of the measured bone is known. The same adjustment factor (10% overestimation for 1 mol/mol% Sr) can be used for all presently available types of instrument and acquisition modes.
The release of radioactive strontium to the environment is of concern due to the strong accumulation of this calcium resembling element in the bone and other tissues. To predict the effects of changes in environmental conditions on the uptake of Sr2+ and Ca2+ by freshwater fish, a Michaelis-Menten type model is introduced that accounts for the effects of chemical speciation, hydrogen ion activity, and metal ion competition. The uptake kinetics were characterized in vivo from short-term exposure experiments using the common carp (Cyprinus carpio) as the model organism. Fish were exposed to a wide range of waterborne Sr2+ (0.2-10,000 microM) and Ca2+ (10-10,000 microM) concentrations and water pH (5.0-8.5). Strontium uptake by the whole body of fish increased with increasing Sr2+ activity, displaying saturation kinetics, but decreased significantly with increasing Ca2+ and H+ activities in the water. Likewise, calcium uptake by the fish decreased with increasing Sr2+ and H+ activities in the water. The model fitted to the pooled data explains 97.5% of the variation in Sr2+ uptake and 86% in Ca2+ uptake over the wide range of exposure conditions and reveals that Sr2+ and Ca2+ inhibit each other completely competitively, while H+ inhibits the uptake of both metal ions in a partially noncompetitive way. This model can be used as a mechanistic tool to predict the uptake of these metals in carp under variable conditions.