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PubMed1995

Intestinal strontium absorption: from bioavailability to validation of a simple test representative for intestinal calcium absorption.

Calcium absorption tests have rarely been validated for being representative for absolute bioavailability (true absorption) or for intraindividual variation. Therefore, we investigated the reproducibility of the absolute bioavailability of strontium chloride, a marker for intestinal calcium absorption, in healthy male volunteers (n = 8) by measuring the area under the plasma strontium concentration-time curve after oral and intravenous administration of strontium. Subsequently, we selected a simple test variable as being representative of absolute bioavailability. The mean absolute bioavailability (+/- SD) was 25% +/- 7%. The best test variable appeared to be the fractional absorption at 240 min (Fc240) after oral intake, which demonstrated the highest correlation with absolute bioavailability (r = 0.66). The intraindividual variations of the data for this variable and for the absolute bioavailability are similar to those described for various absorption tests based on the use of calcium isotopes. Thus, the Fc240 of strontium offers the potential of a simple clinical test for use as a measure of intestinal calcium absorption and its modulation.

Adult↗
PubMed1964

STRONTIUM AND CALCIUM UPTAKE BY THE GREEN ALGA, OOCYSTIS EREMOSPHAERIA.

The uptake of calcium and strontium by a green unicellular alga cultured in media containing these elements in concentrations found in nature is directly proportional to the concentration in the media. Variation in the concentration of either element has a slight inverse influence on the uptake of the other. The increase of strontium uptake when the calcium concentration is very low indicates that strontium is substituted for calcium when calcium is limited and suggests that the alga requires either element.

Calcium↗
PubMed1963

Strontium-90 in hair.

The hair of rats injected with strontium-90 retains a significant amount of the radionuclide. Although the strontium-90 content of hair is variable in these rats and appears to be subject to a variety of influences, determination of the radionuclide content of hair may offer a nondestructive method of estimating strontium-90 in bone.

Animals↗
PubMed1964

STUDIES ON INHIBITION OF INTESTINAL ABSORPTION OF RADIOACTIVE STRONTIUM. II. EFFECTS OF ADMINISTRATION OF SODIUM ALGINATE BY OROGASTRIC INTUBATION AND FEEDING.

A method is reported that enables selective suppression of absorption of radioactive strontium from ingested food material, permitting calcium to remain available to the body. Studies were carried out by measuring blood levels and bone uptake of Sr(89) and Ca(45) at different time intervals after orogastric intubation of rats. The addition of sodium alginate, derived from brown marine algae, to the radioactive isotopes increased the overall physiological discrimination against strontium by amounts up to 60% after 24 hours. This discrimination was further increased by feeding sodium alginate mixed with standard diet in the proportions of 20:80 and 30:70. The observed ratio was reduced by administration of sodium alginate from 0.25 to 0.09.Determination of the limiting dosage in rats is restricted to the amounts which rats will consume. In the event of an inadvertent release of radioactive strontium, human subjects probably could increase their intake of alginate at will, permitting a greater effectiveness of sodium alginate than could be obtained in experimental animals.

Absorption↗
PubMed2006

Strontium ranelate--data on vertebral and nonvertebral fracture efficacy and safety: mechanism of action.

Strontium ranelate is a novel therapy for the treatment of postmenopausal osteoporosis with actions to reduce bone resorption and increase bone formation. In vitro, strontium ranelate has anabolic and antiresorptive activity, increasing collagen and non-collagen protein synthesis, enhancing pre-osteoblast differentiation, inhibiting osteoclast differentiation, and reducing osteoclast function. In animal models, the increase in bone density is closely correlated with increases in biomechanical bone strength. Histomorphometry demonstrates reduced osteoclast surfaces with increased bone formation. Clinical trials in postmenopausal women have demonstrated 3-year fracture efficacy. Reductions in vertebral fracture were seen in patients with and without prevalent vertebral fracture. Nonvertebral fractures were also significantly reduced. In a subgroup of patients at high risk for hip fracture, there was a significant reduction in hip fracture risk. Strontium ranelate is well tolerated with nausea, diarrhea, headache, and dermatitis more frequent in treated patients only for the first 3 months of therapy. Together, these data suggest that strontium ranelate is a well-tolerated and effective therapy for postmenopausal osteoporosis reducing vertebral and nonvertebral fracture by a novel dual antiresorptive and anabolic action on bone.

Animals↗
PubMed2006

Addressing and meeting the needs of osteoporotic patients with strontium ranelate: a review.

Patients with osteoporosis need a safe and effective treatment that reduces the risk of vertebral and non-vertebral fractures, leading to clinical benefits such as reduced back pain and height loss. Strontium ranelate corrects bone turnover, producing a more physiological state. Double-blind, placebo-controlled studies in postmenopausal osteoporosis show it to be effective in reducing vertebral and non-vertebral fracture risks. Treatment efficacy has been documented across a wide range of patient profiles, and appears to be independent of all the major determinants of fracture risk, including the severity of the disease at baseline, the number of prevalent fractures, and the age of the patient. This antifracture efficacy translates into clinical benefits, such as a 20% reduction in the rate of height loss and a 29% increase in the number of patients free of back pain. The effect of treatment with strontium ranelate on well-being has been assessed using the Quality-of-Life Questionnaire in Osteoporosis, which is a supplement to the 36-question Short-Form Health Survey. Treatment with strontium ranelate had a significant beneficial effect on the emotional, physical, and global Quality-of-Life Questionnaire in Osteoporosis scores compared with placebo. The rates of compliance with treatment were over 80% in phase III studies, reflecting the tolerability and safety profile and the ease of administration of this agent. Together with the antifracture data, the clinical benefits and quality of life data endorse the treatment of postmenopausal osteoporosis with strontium ranelate.

Bone Density↗
PubMed1991

Determination of strontium binding to macromolecules.

An equilibrium dialysis technique for determining the binding of strontium to macromolecules is described. The major difficulty to be overcome is that 90Sr has a decay product, 90Y, which is also a beta-emitter. The described protocol is used to determine the Sr binding isotherm to bovine prothrombin fragment 1. The binding is found to be cooperative, somewhat weaker than Ca binding, and to involve approximately nine strontium sites. The stoichiometric equilibrium constants are determined by nonlinear regression. The procedure should be of great utility for many macromolecules that show strontium affinity.

Animals↗
PubMed1999

Strontium and samarium therapy for bone metastases from prostate carcinoma.

A review was performed of all patients who received strontium-89 chloride or samarium-153 ethylenediamine-tetramethylenephosphonate for prostate cancer metastatic to bone at the Royal Brisbane Hospital between 1992 and 1997. There were 57 patients, 38 treated with strontium-89 and 19 with samarium-153. Forty patients had radionuclide therapy alone, and 28/40 (or 70%) responded in terms of experiencing a beneficial effect on pain. In the other 17 patients, the effect of the radionuclide on pain could not be assessed because they received external beam radiotherapy concomitant with a therapeutic radionuclide. There was no difference in response rates between the samarium and strontium groups as measured by the effect on pain or in the time to progression. The median time to progression for all patients was 2-3 months. The present study confirms that following administration of a therapeutic radionuclide, a high proportion of patients experienced improvement of pain, but the time to progression is not long, so that the overall degree of benefit is modest.

Aged↗
PubMed2006

Methods for assessing gastrointestinal absorption of strontium in humans by stable tracer techniques.

Intestinal absorption of strontium from an oral test dose was studied in 13 healthy human volunteers using double tracer techniques with two stable strontium isotopes as tracers. Defined amounts of one isotope were administered orally, while tracer amounts of the second isotope were injected intravenously. Two different methods were used to assess the total fraction absorbed (f1 value). Fractional intestinal strontium absorption can be calculated from the ratio of the two isotopes in plasma or urine samples (in this paper called the double-isotope method) or the convolution integral technique, since both methods provide an accurate estimate of fractional absorption and yield comparable results. The latter additionally provides information on the absorption kinetics in the gastrointestinal tract. The absorption varies with respect to the chemical form and to the amount administered. Absorption patterns are characteristically different for uptake from solutions or from whole meals.

Administration, Oral↗
PubMed1957

Strontium-90 in man.

The world-wide average strontium-90 content of man was about 0.12 micromicrocurie per gram of calcium (1/10,000 of the maximum permissible concentration) in the fall of 1955. A few values as high as 10 times the average have been obtained. This value is in accord with the predicted value based on fallout measurements and fractionation through the soilplant-milk-human chain. With the present burden of strontium-90, this average level should rise to 1 to 2 micromicrocuries of strontium-90 per gram of calcium by 1970.

Calcium↗
PubMed1961

Foliar retention of strontium-90 by wheat.

Wheat harvested from the University of Maryland Agronomy Farm in June 1959 contained 20 to 50 micromicrocuries of strontium-90 per kilogram of grain. More than 90 percent of the strontium-90 came from deposition on aboveground plant parts, and less than 10 percent was taken up through the soil. About 1 to 2 percent of the strontium-90 fallout during the time the heads were exposed was retained in the grain.

Head↗
PubMed1962

Strontium-90 in the 1959 United States wheat crop.

A broad sampling of the 1959 United States wheat crop has been analyzed for the presence of strontium-90. The level of strontium-90 found in these samples is in general agreement with the findings of other investigators, with the exception that the highest levels of strontium-90 in wheat were found in samples from Oklahoma.

Agriculture↗
PubMed2004

[Strontium-89 diagnosis and therapy of bone metastases].

A clinical test of strontium-89 chloride effect was carried out in 150 patients with bone metastases and bone pain from different patterns of tumor. Different types of bone lesions were considered. Pain-relieving effect was reported in 77%, irrespective of lesion gravity. There was no response to strontium-89 chloride in 150 patients with bone metastases. It mostly occurred in cases of lysis. Strontium-89 chloride therapy contributed to partial bone tissue repair. It is indicated as a component of complex treatment for bone metastases.

Analgesics↗
PubMed1993

Strontium-89--precursor targeted therapy for pain relief of blastic metastatic disease.

Strontium-89 is a radioactive calcium analog that provides an energetic beta particle for radiation therapy of osteoblastic disease. Strontium-89 is used as palliative therapy with the primary goal being pain relief. More than 500 patients with painful blastic metastatic disease were treated at University of Kansas Medical Center since the initiation of the first clinical trial there 15 years ago. Most patients have had metastatic prostate cancer to bone or breast cancer, as these tumors are commonly associated with bone pain as their primary clinical management problem. Improvement (decrease in pain, increase in physical activity level) was noted in 80% of patients with prostate carcinoma and 81% of patients with metastatic breast cancer to bone. Marrow toxicity levels were acceptable. The therapy can be repeated at 3-month intervals. Strontium-89 is a safe and effective systemic therapy for painful blastic metastatic disease. There is no longer any reason why the vast majority of persons with painful blastic metastatic disease should continue to hurt.

Bone Neoplasms↗
PubMedDate not supplied

Contribution to the penetration of radionuclides across the skin. Concentration dependence of strontium through the skin in vitro.

Toxicological studies of radionuclide passage across the skin, which represents a crucial barrier of radiation, are important for ensuring the quality of the environment. Both (137)Cs and (90)Sr are most frequently involved in radionuclide contamination of the human body. In our study, we selected (90)Sr because this radionuclide is chemically very close to the bio-element calcium. The permeation of (90)Sr from donor solution across the intact skin of 5- or 9-day-old rats (5DR, 9DR) and across stripped and split skin of the 5DR was studied. The experiments in vitro were carried out using vertical diffusion cells. Strontium chloride (SrCl(2)) was used as carrier in the donor solution in different concentrations. Liquid scintillation spectrometry was applied for radiation detection. The experiments showed that: the permeated fraction of (90)Sr(2+) was indirectly proportional to the carrier concentration in the donor solution; the stratum corneum was found to be the principal penetration barrier of strontium; and in the case of the 9DR the dominant route of strontium penetration was along the follicles.

Animals↗
PubMed2004

Prospective study on exclusive, nonsurgical strontium-/yttrium-90 irradiation of pterygia.

PURPOSE: Prospective study to evaluate consecutive treatment results and to demonstrate safety and efficacy of nonsurgical, exclusive strontium-/yttrium-90 beta-irradiation of nonoperated pterygia. PATIENTS AND METHODS: Between November 1999 and March 2002, 20 patients with 21 primary pterygia and six patients with recurrent pterygia after former surgery were treated with exclusive strontium-/yttrium-90 irradiation up to a total dose of 3,600 cGy (six fractions) and 4,800 cGy (eight fractions), respectively. All patients were referred from a single institution. The mean follow-up is 35.6 +/- 7.3 months (range 24-48 months). RESULTS: Prior to irradiation the mean horizontal diameter of all pterygia was 2.6 mm and shrank to a mean diameter of 1.6 mm after treatment (p = 0.0011, Student's t-test). The treatment led to a reduction in size of all 21 primary and all six recurrent pterygia. Visual acuity reached a value of 0.73 before and 0.82 after treatment. This improvement was not significant in Student's t-test (p = 0.12). The visual acuity did not decrease in any patient, complications were not observed, and in none of the 27 pterygia a recurrence developed CONCLUSION: Exclusive strontium-/yttrium-90 irradiation of the early and moderately advanced pterygium is a very efficient and very well-tolerated method of treatment. As to the therapeutic management, it is suggested to apply beta-irradiation prior to the development of an astigmatism-relevant pterygium, which requires excision.

Adult↗
PubMed1998

Strontium plaque irradiation of subfoveal neovascular membranes in age-related macular degeneration.

PURPOSE: To determine the effect of focal strontium-90 plaque radiotherapy on subfoveal choroidal neovascularization in patients with age-related macular degeneration. METHODS: Twenty patients with age-related macular degeneration, presenting with a recent subfoveal neovascular membrane, were treated with local episcleral radiotherapy using a strontium-90 applicator. The applicator was applied to the sclera under the macular region and held there tightly for 54 min to obtain a dose of 15 Gy at a depth of 1.75 mm. The main parameters evaluated at follow-up after 3, 6 and 12 months were visual acuity and changes in fluorescein angiography. Twelve untreated patients with the same criteria were followed as controls. RESULTS: Early effects of radiation could be seen at 3 months, but became more obvious after follow-up for 6 and 12 months. At 6 months, regression of the choroidal neovascularization was detected in 14/19 patients (74%) as a decrease in the size of the lesion or as diminished leakage in late-phase fluorescein angiography. Likewise, in 14/19 patients (74%) at 12 months the neovascular membrane was partially or totally occluded. In all patients showing regression of the choroidal neovascular membrane, the neurosensory detachment had also dried. Visual acuity was unchanged (within 1 line) or improved in 11/20 (55%) and 9/20 (45%) treated patients after 6 and 12 months, respectively. In the controls, the choroidal neovascularization had increased in size in 9/12 patients (75%) at the last follow-up (mean 12.0 months). Visual acuity was unchanged in 3/12 patients (25%). CONCLUSION: Local low-energy beta irradiation with a strontium-90 applicator can induce regression of choroidal neovascularization. The effect of irradiation is seen as a decrease in the size of the choroidal neovascular membrane and disappearance of the neurosensory detachment and exudates.

Aged↗
PubMed1998

Results of treatment of choroidal malignant melanoma with high-dose-rate strontium-90 brachytherapy. A retrospective study of 46 patients treated between 1983 and 1995.

PURPOSE: We review the results of treatment of small to medium-sized choroidal malignant melanomas after high-dose-rate brachytherapy with a strontium-90 applicator. METHODS: The applicator is positioned against the sclera using an afterloading technique. Brachytherapy is completed in a single session lasting 2-4 h with the patient under local anaesthesia. From September 1983 until March 1995, 46 eyes were treated in this way. Most tumours were 7-11 mm in diameter (range from 4.5-15 mm) with a mean height of approximately 3 mm (range from 1.5-7 mm). Follow-up ranged from 6 months to 12 years (mean 49 months). RESULTS: Thirty of the 46 eyes had at the final evaluation a nonevolutive scar (20 of these after a single application, the others with some additional treatment). In 13 eyes the tumours were in involution but their complete destruction was not yet certain, and 3 eyes were enucleated for local recurrence. Three patients developed systemic metastases. No radiogenic complications were noticed. CONCLUSION: Strontium-90 brachytherapy is a valuable and safe treatment technique for small to medium-sized choroidal malignant melanomas. In addition the use of a strontium-90 applicator is inexpensive thanks to this element's long half-life and the short application time.

Adult↗