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PubMed1997

Analysis of strontium metabolism in humans on the basis of the Techa river data.

Age and sex features of strontium metabolism have been analyzed on studies of the population residing on the banks of the Techa river which was contaminated by fission products during the years 1949-1956. Measurements of 90Sr body burden have been performed since 1974 using a whole-body counter, and these have made it possible to estimate age-specific long-term retention and elimination rates for men and women. Regarding the retention that correlated with the respective maturation ages, distinct sex differences have been observed for adolescents, whereas only postmenopausal women showed a sharp increase of their elimination rates. There were no differences concerning the reproductive ages. Our experimental findings have a clear physiological interpretation and can be used to develop metabolic models for bone-seeking radionuclides.

Adolescent↗
PubMed1979

The use of strontium-90 in the treatment of carcinoma in situ of the conjunctiva.

Four patients with carcinoma in situ were treated with strontium-90 beta ray application. The dose used was 4,500 rads after surgical removal or with small recurrent tumor and 7,000 rads for primary treatment. All patients were disease-free at follow-up periods of 48 to 320 months after treatment. One patient required superficial x-ray treatment for recurrent disease. No serious complications developed with the treatment and no progressive cataracts have occurred.

Aged↗
PubMed1982

Effects of strontium administration on rat molar morphology.

Strontium at concentrations of 0, 50 and 150 mg/l was given to rats during pregnancy and to the pups during a pre- and post-weaning period. Measurements were made on first and second mandibular molars to assess the morphology of tooth and fissure dimensions, and enamel and dentine thickness. A significant increase in horizontal and vertical dentine thickness was associated with a level of 50 mg Sr/l, a concentration previously found to be associated with decreased caries prevalence in rats.

Animals↗
PubMed1993

The structure of dentine after the injection of strontium chloride by backscattered electron imaging in the scanning electron microscope.

The subcutaneous injection of 0.5 ml of 20% aqueous strontium chloride produced a distinct calciotraumatic response in rat incisor dentine. In both the labial and lingual dentine this consisted of an unmineralized layer comprising continuous interglobular spaces. Lingually this unmineralized layer was sharply defined and about 1-2 microns in width but labially it was more irregular, diffuse and difficult to measure. Labially and lingually the dentine formed after the unmineralized layer hypomineralized in comparison to the rest of the dentine. Within the hypomineralized labial dentine a diffuse, more intensely hypomineralized layer was often present. The appearance of the unmineralized layer probably reflects the differences in structure between labial and lingual dentine, that is, small linear calcospherites lingually and large irregular calcospherites labially.

Animals↗
PubMed1984

The biology of strontium: interactions with the mammalian crystalline lens.

Rabbit lenses incubated in a Ca-free medium gain Na and lose K, but this effect is reduced by the presence of strontium. Little Sr enters the lens under in vitro conditions and that which is present does not appear to significantly enter the lenticular cells. The Sr present, however, appears to be displaced by lanthanum, suggesting that Sr is interacting with the cell surface. This outer 'bound' Sr does not interfere with exchanges of Ca across the cell membrane but it may contribute to the control of lens permeability to Na and K. Uptake of Sr can be enhanced by exposure of the lens to a Ca-free medium or the Ca-Mg ionophore A23187.

Animals↗
PubMed1987

A four compartment model to study the kinetics of strontium metabolism in man.

Many drugs confer upon the body the characteristics of a four compartment model. This paper deals with the estimation of pharmacokinetic parameters of a four compartment model to study the distribution of strontium in the organism. The central compartment (where the introduction of the material takes place) is connected to two other compartments (which represent the organic fluids) and one of them is connected to the fourth compartment (which represents the fraction that can be exchanged in the bone). The elimination from the central compartment is through urine and the elimination from the third compartment is in the form of a non-exchangeable deposit. The method of solution involves an optimization method which provides the global minimum of delta, a single variable function. The model is tested for different sets of data and the results are compared with those obtained by the generalized least square method.

Computer Simulation↗
PubMed1992

Effect of strontium on action potential repolarization in rabbit sinoatrial node cells.

Using standard microelectrode techniques, the effects of strontium (Sr++) ions on action potential (AP) repolarizations in rabbit sinoatrial node (SAN) cells were studied. In a nominally magnesium-free, calcium-free solution, Sr++ (0.5-3.55 mmol) produced an early afterdepolarization (EAD) and a prolongation of the AP. Until now, no experimental evidence has been presented in favor of an EAD mechanism in SAN cells. Superfusion of the SAN cells with 0.5 mmol Sr++ solution containing 1-5 mmol magnesium (Mg++) or 0.5 mmol calcium (Ca++) did not induce the EAD. Increasing the extracellular Mg++ to 1-5 mmol did not affect the EAD induced by superfusion with 3.55 mmol Sr++ solution. Increasing the extracellular Ca++ to 0.5 mmol suppressed the 3.55 mmol Sr(++)-induced EAD. The presence of 0.3 mmol manganese (Mn++) suppressed the EAD induced by superfusion with 0.5 mmol Sr++ solution. The EAD did not occur in the presence of 1 x 10(-6) mol nitrendipine or 2 x 10(-6) mol diltiazem hydrochloride. The presence of 0.03 mmol Mn++ did not significantly alter the 0.5 mmol Sr(++)-induced EAD. These results suggest that a slow inward Sr++ current through the Ca++ channel has an important role in the development of the EAD.

Action Potentials↗
PubMed1982

Dissociation of aldosterone response to angiotensin II and potassium in the presence of strontium.

the effect of Ca2+, Sr2+ and Ba2+ on aldosterone output was studied in basal conditions and under the stimulus of angiotensin II, potassium and ACTH. Aldosterone production was measured in glomerulosa cells isolated from bovine adrenal glands and incubated in Krebs-Ringer solution in which 1.25 mM Ca2+ was substituted by Sr2+ or Ba2+. Strontium and Ba2+ can substitute for Ca2+ in steroid production when angiotensin II or ACTH were the aldosterone-stimulating agents. The relative aldosterone production was Ca greater than Sr greater than Ba. However, when the steroidogenic effect of potassium was measured under similar conditions, neither Sr2+ nor Ba2+ were able to replace Ca2+ responses. The results suggest a dissociation between the calcium mediated stimulation of aldosterone production by angiotensin II and potassium.

Adrenal Cortex↗
PubMed1989

Calcium release induced by inositol 1,4,5-trisphosphate in thymocyte microsomes. Inhibition by barium and strontium.

The properties of calcium transport in microsomes and the effect of inositol 1,4,5-trisphosphate (IP3) on accumulated calcium were studied in rat thymocytes. Active calcium transport shows an apparent affinity constant for calcium of 0.2 +/- 0.01 microM and a maximal velocity of 2.3 +/- 0.6 nmol/mg/30 min (mean +/- SD). IP3 was able to induce release of calcium only in the absence of oxalate. At 6 microM ambient free calcium, half-maximal effect of IP3 was attained at 2 microM and maximal calcium release was produced by IP3 concentrations over 5 microM. Barium and strontium did not modify calcium uptake by microsomes but markedly inhibited the action of IP3.

Adenosine Triphosphate↗
PubMed1993

Strontium and barium induce exocytosis in electropermeabilized neutrophils.

Calcium, strontium and barium induced an exocytotic response in electropermeabilized rabbit neutrophils while magnesium was without any effect. The extent of enzyme release was found to depend upon the concentration of these cations. For all cations, an optimum concentration was found with the same maximum enzyme release. At concentrations higher than optimum a decrease in lysozyme release was observed. Efficiency to induce enzyme release was in the order: Ca2+ > Sr2+ > Ba2+. Enzyme release was significantly enhanced by guanosine-5'-[gamma-thio]triphosphate (GTP gamma S) resulting in a shift to the left of the dose/response curve. The enhancement by GTP gamma S was strongest with Ca2+, was less with Sr2+, and was very little with Ba2+. The time course of lysozyme release was the same for Ca2+, Sr2+, and Ba2+ in the presence and absence of GTP gamma S when suboptimal cation concentrations were used. A decrease in responsiveness to the effectors after electropermeabilization was observed with Ca2+, Sr2+ and Ba2+ in the presence and absence of GTP gamma S. The lysozyme release induced by the different cations was not inhibited by the protein kinase C inhibitor staurosporine and was slightly affected by pertussis toxin. Ca2+ and Sr2+, but not Ba2+, potentiated formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) induced enzyme release in intact neutrophils. The divalent cation ionophore A23187 induced enzyme release in the presence of Ca2+ and Sr2+ but not in the presence of Ba2+. The results obtained with electropermeabilized neutrophils indicate that Sr2+ and Ba2+ can act as substitutes for Ca2+ in activating exocytosis, and that permeabilized neutrophils provide the best tool to investigate the effects of alkaline earth ions in exocytosis.

Animals↗
PubMed1977

Short-term toxicity of strontium chloride in rats.

A range-finding experiment with strontium chloride hexahydrate (0, 3, 30, 300 and 3000 ppm in the diet) and subsequently a 90-day test with the same compound at dose levels of 0, 75, 300, 1200 and 4800 ppm in a semipurified diet was carried out with SPF-derived Wistar-rats. The diet contained adequate levels of Ca, Mg, P and Vit.D3. Growth, food intake, behaviour and mortality were measured, extensive haematology and clinical biochemistry carried out, organ weights determined, X-ray photographs of the bones taken and complete histopathological examination was performed. In addition Sr-content of blood, bone and muscles was determined. Thyroid weights were significantly increased in the males of the 1200 and 4800 ppm group. Histological evidence for increased thyroid activity was noticed in the males of the 4800 ppm group. Pituitary weights were significantly decreased in the females of the 300 ppm and 4800 ppm group, but not of the 1200 ppm group. A histologically confirmed glycogen depletion of the liver was noted biochemically in the highest dose group (4800 ppm). Sr-content in bone was increased at all dose levels having a constant level from 4 weeks onwards, thus indicating that a no effect level cannot be established. If the increased Sr-concentration in the bone can be considered a non-toxic effect, the non-toxic effect level appears to be 309 ppm.

Animals↗
PubMed1991

Strontium toxicity in Drosophila melanogaster.

The Drosophila strains v;bw and Austin represent the extremes in resistance and sensitivity, respectively, to the toxic effects of CdCl2 in the diet. Using the six genotypes containing the possible combinations of the three main chromosomes for v;bw and Austin, we had shown previously that the gene(s) for cadmium resistance is on the X-chromosome. In this paper it is shown, using the same six genotypes, that the gene(s) for strontium resistance is on the second chromosome, as measured by LC50 values.

Animals↗
PubMed1983

Depolarization-dependent protein phosphorylation in rat cortical synaptosomes: the effects of calcium, strontium and barium.

Depolarization of synaptosomes increases the phosphorylation of a number of proteins in a calcium-dependent manner. The concentration of calcium required for optimum stimulation was 0.1 mM, with higher concentrations up to 2.5 mM being progressively less effective. Calcium was significantly better than strontium at increasing depolarization-dependent protein phosphorylation, while barium had no stimulating effect at concentrations above 0.1 mM. The order of potency of these ions is consistent with a calmodulin-stimulated protein kinase being activated on entry of calcium into synaptosomes, but is not consistent with the known efficacy of these ions in stimulating neurotransmitter release. The data show for the first time that phosphorylation of proteins may not be a prerequisite for neurotransmitter release.

Adenosine Triphosphate↗
PubMed1985

Serum strontium estimation as a diagnostic criterion of the type of drowning water.

The estimation of serum strontium in rabbits before and after death by drowning, in soft or hard water, or by barbiturate intoxication is highly promising as a method in medicolegal practice. It not only diagnoses drowning but also indicates the type of drowning water. Atomic absorption spectrophotometry is a good method for the estimation.

Animals↗
PubMed1990

Ion exchange chromatography on a new form of tin dioxide for the isolation of strontium radioisotopes from fission products: an application to milk samples.

An amorphous, partially-reduced tin dioxide, having properties of an inorganic exchanger, was tested for application to fission product separations. Due to the good sorption of both strontium and barium the application of the exchanger to radiostrontium isolation from fission product mixtures is subject to important restrictions. An application to 90Sr determination in milk is proposed.

Animals↗
PubMed1987

Treatment of metastatic bone pain with strontium-89.

We have utilized 89Sr as palliative treatment for bone pain secondary to metastatic cancer in the skeleton of over 200 patients. The best results have been in patients with carcinoma of the prostate (80% response rate) and breast (89%). Results in a small number of patients with a variety of other cell types were not nearly as encouraging. Strontium-89 provides excellent palliation in the management of bone pain secondary to prostate and breast carcinoma.

Adolescent↗
PubMed1989

Strontium-90 eye application.

Details of the Strontium-90 Eye Application including equipment, irradiation technique, radiation safety and data are presented.

Brachytherapy↗
PubMed1990

Effects of low doses of strontium on bone quality and quantity in rats.

Strontium (Sr) has been shown to increase bone mass when given at low doses. In this study, the diets of rats containing 0.50% calcium were supplemented with Sr (0.19 and 0.40% of SrCl2 orally) for periods of four and eight weeks. Long bones and vertebrae were studied by density fractionation and each fraction was analyzed chemically. X-ray diffraction was used to determine crystal size. Static and dynamic histomorphometric parameters of bone formation were also measured. We found a shift towards lower density in the mineralization profiles of Sr supplemented rats (0.40%), as well as a decrease in bone crystal size at the larger dose of Sr. The CO3 content and the Ca/Sr ratio of the bone decreased with increasing Sr content. We found an increase in the vertebral trabecular bone volume together with an increase in osteoid volume in Sr supplemented rats. This study shows that Sr at the larger dose induces bone hypomineralization as well as an increase in bone mass in rats fed a relatively low calcium diet.

Animals↗