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At least 577 records · Page 32Linked to original sources
PubMed1990

Strontium-90 for conjunctival AIDS-related Kaposi's sarcoma: the first case report.

AIDS-related Kaposi's sarcoma is often treated by local therapy for physically or cosmetically disabling symptoms. We present the first case of a bulbar conjunctival Kaposi's sarcoma lesion to be treated with a strontium-90 ophthalmic applicator. The treatment is simple, effective and well tolerated and we recommend that it should be considered for the management of superficial Kaposi's sarcoma lesions of the conjunctiva.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Palliation of bone metastases in prostate cancer. Hemibody irradiation or strontium-89?

The palliation of bone pain is a common clinical problem once metastatic prostate cancer has escaped from hormonal control. This retrospective study compares the results of treatment using hemibody irradiation (HBI) at the Royal Marsden Hospital (27 cases) with isotope therapy using the bone-seeking isotope strontium-89 (89Sr) at Southampton General Hospital (51 cases). Prior to analysis patients were matched for potential prognostic factors (performance status, bone scan extent of disease, age, histology and duration of hormone response) to minimize the effect of treatment selection bias. Pain control assessed at 3 months was similar for HBI and matched 89Sr cases, with 63% and 52% respectively showing some benefit. Median survival was similar for these groups at 20 and 21 weeks respectively. The unmatched 89Sr group, which had more favourable prognostic factors, had a better outcome with 96% showing improvement in pain and with a median survival of 59 weeks. Subsequent univariate analysis demonstrated that performance status and extent of disease on bone scan were of overriding importance in determining outcome. Transfusion requirements were higher for the HBI group than for the matched 89Sr group (50% and 25% respectively) but other bone marrow toxicity was similar. Despite routine anti-emetic therapy 37% of patients treated with HBI had some nausea or vomiting. Although expensive, 89Sr appears as effective a treatment option as HBI. Response is most likely with either approach when patients have a good performance status and a limited extent of disease.

Actuarial Analysis↗
PubMed1991

The role of strontium-90 beta irradiation in the management of pterygium.

A pterygium is a benign, usually progressive fibrovascular overgrowth of the conjunctiva usually arising at the inner canthus of the eye which may cause local symptoms, particularly if large and impinging on the cornea. The treatment of choice for symptomatic pterygia is surgical excision, but early proliferation of fibroblasts and vascular buds leads to recurrence in a large proportion of cases. We review the published results of adjuvant postoperative beta irradiation using an ophthalmic applicator containing strontium-90 which is effective at reducing recurrence to an acceptable level. This treatment is well tolerated in the short term, and although a number of late sequelae are recognized, these are extremely uncommon in everyday clinical practice.

Combined Modality Therapy↗
PubMed2001

An ultrastructural study of osteoclasts and chondroclasts in poorly calcified mandible induced by high doses of strontium diet to fetal mice.

A high dose strontium diet was fed to fetal mice from day 1 of gestation to birth in order to investigate the ultrastructural changes of osteoclasts/chondroclasts when associated with poorly calcified bone/cartilage. Calcification in the mandibular bone and condylar cartilage was extensively inhibited by this diet. Multinucleated osteoclasts and chondroclasts were observed on the mandibular alveolar bone and in the resorption area of the condylar cartilage, respectively. However, both cell types never formed ruffled borders and clear zones at the cell surfaces facing the matrices indicative of bone resorption, although they had well-developed organelles and vacuoles. Furthermore, they revealed signs of phagocytosis of the matrix vesicles. These results indicate that osteoclasts/chondroclasts can exhibit phagocytotic activity in response to requirements.

Animals↗
PubMed1998

Measurement standards for strontium-89 for use in bone palliation.

Strontium-89 standards have been prepared for use in calibrating instruments in the measurement chain from production in reactors to administration in the clinic or radiopharmacy. Alternate reactor production schemes were evaluated to yield high purity 89Sr with minimum 85Sr impurity. Following purification to remove radionuclidic impurities, samples of 89Sr were standardized by high-efficiency liquid-scintillation counting with a relative expanded uncertainty (intended to approximate two standard deviations) of 0.48%. A Standard Reference Material, SRM 4426A, was prepared and distributed to radiopharmaceutical manufacturers and other customers. The standard sources of 89Sr were used in different geometries to calibrate high purity Ge semiconductor detectors, re-entrant ionization chambers and commercial radionuclide calibrators. The latter included Capintec dose calibrators and the Capintec beta C NaI(Tl) scintillation counter.

Bone Diseases↗
PubMed2001

Cesium and strontium ion exchange on the framework titanium silicate M2Ti2O3SiO4.nH2O (M = H, Na).

The ion exchange properties of the titanium silicate, M2Ti2O3SiO4.nH2O (M = H, Na), toward stable and radioactive 137Cs+ and 89Sr2+, have been examined. By studying the cesium and strontium uptake in the presence of NaNO3, CaCl2, NaOH, and HNO3 (in the range of 0.01-6 M) the sodium titanium silicate was found to be an efficient Cs+ ion exchanger in acid, neutral, and alkaline media and an efficient Sr2+ ion exchanger in neutral and alkaline media, which makes it promising for treatment of contaminated environmental media and biological systems.

Cesium↗
PubMed2001

Chemical equilibria model of strontium-90 adsorption and transport in soil in response to dynamic alkaline conditions.

Strontium-90 is a major hazardous contaminant of radioactive wastewater and its processing sludges at many Department of Energy (DOE) facilities. In the past, such contaminated wastewater and sludge have been disposed in soil seepage pits, lagoons, or cribs often under highly perturbed alkaline conditions (pH > 12) where 90Sr solubility is low and its adsorption to surrounding soil is high. As natural weathering returns these soils to near-neutral or slightly acidic conditions, the adsorbed and precipitated calcium and magnesium phases, in which 90Sr is carried, change significantly in both nature and amounts. No comprehensive computational method has been formulated previously to quantitatively simulate the dynamics of 90Sr in the soil-groundwater environment under such dynamic and wide-ranging conditions. A computational code, the Hydrologic Utility Model for Demonstrating Integrated Nuclear Geochemical Environmental Responses (HUMDINGER), was composed to describe the changing equilibria of 90Sr in soil based on its causative chemical reactions including soil buffering, pH-dependent cation-exchange capacity, cation selectivity, and the precipitation/dissolution of calcium carbonate, calcium hydroxide, and magnesium hydroxide in response to leaching groundwater characteristics including pH, acid-neutralizing capacity, dissolved cations, and inorganic carbonate species. The code includes a simulation of one-dimensional transport of 90Sr through a soil column as a series of soil mixing cells where the equilibrium soluble output from one cell is applied to the next cell. Unamended soil leaching and highly alkaline soil treatments, including potassium hydroxide, sodium silicate, and sodium aluminate, were simulated and compared with experimental findings using large (10 kg) soil columns that were leached with 90Sr-contaminated groundwater after treatment. HUMDINGER's simulations were in good agreement with dynamic experimental observations of soil exchange capacity, exchangeable cations, total 90Sr, and pH values of layers within the soil columns and of column effluents.

Adsorption↗
PubMed2004

Mechanisms of strontium and uranium removal from high-level radioactive waste simulant solutions by the sorbent monosodium titanate.

High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.

Adsorption↗
PubMed2006

Strontium speciation during reaction of kaolinite with simulated tank-waste leachate: bulk and microfocused EXAFS analysis.

Radioactive strontium (90Sr) is an important constituent of the complex wastes from past nuclear weapons production and has been stored in underground tanks at U.S. DOE sites (e.g., Hanford, WA). Using bulk and microfocused EXAFS spectroscopy, we examined temporal changes in solid-phase Sr speciation in kaolinite samples reacted for 1-369 d with high-pH, high ionic strength synthetic tank-waste leachate containing Sr(2+) and Cs(+) at 10(-3) mol kg(-1). Analyses of bulk EXAFS spectra showed that Sr initially forms a precipitate by 7 d with a local structure similar to SrCO(3-) (s). At 33 d, microfocused EXAFS of individual particles in one sample revealed a mixture of hydrated and dehydrated Sr associated with neoformed sodalite-type phases. At aging times of 93 d and longer, bulk EXAFS spectra and supporting characterizations indicated nonexchangeable Sr with a local structure consistent with incorporation into increasingly crystalline aluminosilicate particles, particularly sodalite. These experimental studies suggest that irreversible trapping of radionuclides occurs if they are present during the formation and aging of feldspathoid alteration products of local Si-bearing sediment minerals. This may serve as an effective contaminant sequestration mechanism at sites such as Hanford.

Carbonates↗
PubMed2006

Use of strontium isotopes to identify buried water main leakage into groundwater in a highly urbanized coastal area.

Previous studies indicate that the local aquifer systems in the Mid-Levels, a highly urbanized coastal area in Hong Kong, have commonly been affected by leakage from water mains. The identification of leakage locations was done by conventional water quality parameters including major and trace elements. However, these parameters may lead to ambiguous results and fail to identify leakage locations especially where the leakage is from drinking water mains because the chemical composition of drinking water is similar to that of natural groundwater. In this study, natural groundwater, seepage in the developed spaces, leakage from water mains, and parent aquifer materials were measured for strontium isotope (87Sr/86Sr) compositions to explore the feasibility of using these ratios to better constrain the seepage sources. The results show that the 87Sr/86Sr ratios of natural groundwater and leakage from water mains are distinctly different and thus, they can provide additional information on the sources of seepage in developed spaces. A classification system based on the aqueous 87Sr/86Sr ratio is proposed for seepage source identification.

Cities↗
PubMed2006

The imidazole role in strontium beta-diketonate complexes formation.

A selection of new strontium beta-diketonate derivatives (imH2)2[Sr2(beta-dike)6] [where imH = imidazole and beta-dike = tfac (tfacH = 1,1,1-trifluoro-2,4-pentanedione), tfbz (tfbzH = 1,1,1-trifluoro-4-phenyl-2,4-butanedione), or hfac (hfacH = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione)], [Sr2(tfac)4(Meim)2(H2O)2], (MeimH)2[Sr(beta-dike)4] (where Meim = 1-methylimidazole and beta-dike = tfbz or hfac), [Sr2(thd)4(imH)2(EtOH)], and [Sr2(thd)4(Meim)2(EtOH)] (where thdH = 2,2,6,6-tetramethyl-3,5-heptanedione) have been synthesized and fully characterized. (imH2)2[Sr2(beta-dike)6] and (MeimH)2[Sr(beta-dike)4] are di- and mononuclear Sr anionic complexes, respectively, while [Sr2(tfac)4(Meim)2(H2O)2], [Sr2(thd)4(imH)2(EtOH)], and [Sr2(thd)4(Meim)2(EtOH)] are neutral dinuclear molecular derivatives. The derivative (imH2)2[Sr2(hfac)6] slowly decomposes in solution under aerobic conditions, giving (imH2)2[Sr(H2O)2(tfa)3](tfa) (tfaH = trifluoroacetic acid), which is an ionic compound containing polynuclear anionic chains composed of Sr(H2O)2(tfa)3 units. When a deficiency of imH is employed, the thdH proligand forms not only the dinuclear derivative [Sr2(thd)4(imH)2(EtOH)] but also an additional product with the formula [Sr(thd)2(H2O)2(EtOH)], in which the Sr atom is seven-coordinated. A complete solid-state characterization has been accomplished by comparing X-ray and solid-state 13C NMR data. Elucidation of the H-bond interaction between the heterocyclic rings and metal complexes by cross-polarization magic-angle-spinning 15N NMR is also reported.

Crystallography, X-Ray↗
PubMed2001

Crystal structure of the hydrated strontium salt of methotrexate: two independent molecules with different conformations.

The crystal and molecular structure of methotrexate has been determined by X-ray diffraction from a highly hydrated triclinic crystal form in which the asymmetric unit contains two independent methotrexate molecules with their glutamate carboxyl groups coordinated to two strontium ions. The two methotrexates exhibit differing conformations: They are almost related to one another by a pseudocenter of symmetry. This places the C(9)-N(10) bond vectors on opposite sides of the planes of the pteridine rings. The 2,4-diaminopteridines form 2-fold symmetry-related hydrogen-bonded dimers as well as hydrogen bonds to benzoyl carbonyl oxygens and lattice water molecules. This structure provides experimental proof of the existence of pteridine conformers through rotation about the C(6)-C(9) bond. Comparison of these conformers with other free and enzyme-bound methotrexate conformations shows them all to be different and illustrates the ability of the molecule to adapt to its chemical environment. The results from this crystal structure determination are experimental proof that methotrexate has not one preferred molecular conformation but may freely rotate about several bonds. They also suggest that the dihydrofolate reductase-bound methotrexate conformation is greatly influenced by the specific binding site environment of the enzyme.

Antimetabolites, Antineoplastic↗
PubMed2004

Strontium substituted calcium phosphate biphasic ceramics obtained by a powder precipitation method.

Strontium (Sr) substituted calcium phosphate ceramics were fabricated using a powder precipitation method. The Sr ions were added up to 8 mol % to replace the Ca ions during the powder preparation. Composition analysis showed that the added Sr was not fully incorporated within the as-precipitated apatite structure, presumably being washed out during the powder preparation. After calcination, the Sr containing powders were crystallized into apatite and tricalcium phosphate (TCP), that is, biphasic calcium phosphates were formed. The amount of TCP increased with increasing the Sr addition. The lattice parameters of the calcined powders increased gradually with Sr substitution in both the a- and c-axis. However, the obtained values deviated slightly from the calculated ones at higher Sr additions (>4%) due to the partial substitution of Sr ions. The microstructure of the sintered bodies changed with the Sr addition due to the formation of TCP. The Vickers hardness increased slightly from 5.2 to 5.5 MPa with increasing Sr addition, which was driven by the HA+TCP biphasic formation. The osteoblast-like cells cultured on the Sr-substituted biphasic sample spread and grew actively. The proliferation rate of the cells was higher in the samples containing more Sr. The alkaline phosphate activity of the cells was expressed to a higher degree with increasing Sr addition. These observations confirmed the enhanced cell viability and differentiation of the Sr-substituted biphasic calcium phosphate ceramics.

Alkaline Phosphatase↗
PubMed2004

[Contamination of the food chain with caesium-137 and strontium-90 in Switzerland].

One task of the field physiology of nutrition is the monitoring of the quality of feedstuffs. Rations may consequently be prepared with unadulterated components. This review uses the example of contamination with the radionuclides caesium-137 und strontium-90 and shows how these two unwanted substances reach the end host via the food chain and how their untoward effects are expressed in animals and humans. The extent of the contamination with artificial radioactivity is followed with periodical measurements according to the program of the Division for Radiological Protection of the Swiss Federal Office of Public Health. The interpretation of the measurements and the directives of this division are designed to protect primarily human health, but also that of animals.

Animals↗
PubMed1981

Mice treated with strontium 90: an animal model deficient in NK cells.

Treatment of BALB/c mice with radioactive isotopes of the bone-seeking element strontium reduces the percentage of specific NK-cell cytotoxicity to only 2.6%, compared with 13.6% for normal BALB/c and 36.3% for athymic (nude) BALB/c. The syngeneic plasmacytoma NS-1 was used as target in a 4th in vitro NK-cell microassay. Marrow cellularity in treated mice is reduced to 12.5% of controls, but haemopoietic and stem-cell functions are taken over by the spleen and the peripheral blood picture remains relatively normal. Allogenic (H-2k) tumour transplants are rejected normally with good anti-H-2k alloantibody response. Haemopoietic and T- and B-cell functions are therefore substantially intact, and the defect seems confined to NK cells. In vivo, after s.c. inoculation of 10(6) NS-1 cells, 8/12 controls grew a solid tumour after a mean delay of 30.5 +/- 1.25 (s.e.) days, whereas 5/6 90Sr-treated mice grew the tumours after a delay of only 10.5 +/- 1.8 days. This markedly reduced delay in the 90Sr-treated mice lends support to suggestions that NK cells play an important role in resisting the establishment of tumour foci (i.e. in antitumour surveillance). Mice treated with 90Sr could be useful in evaluating the in vitro role of NK cells.

Animals↗
PubMed2003

Trace ion analysis of sea water by capillary electrophoresis: determination of strontium and lithium pre-concentrated by transient isotachophoresis.

The applicability of capillary zone electrophoresis (CZE) to ions having relatively low natural occurrences in sea water is limited by method's relatively poor concentration detection sensitivity. A combination of CZE with indirect UV detection and transient isotachophoresis (tITP) pre-concentration was developed to evolve the CZE practical utility towards the quantitative determination of the minor sea water cationic components, strontium and lithium. The ITP stacking criterion at the initial stage of a CZE separation was met by taking a highly mobile sodium, the principle matrix cation, to perform the role of a leading ion, whereas the moderately mobile sample macrocomponents, Ca2+ and Mg2+, acted as the terminating ion. The carrier electrolyte, consisting of 10 mM 4-methylbenzylamine and 1.5 mM citric acid at pH 4.8, was found to be optimal to accommodate both analyte cations in the ITP range and then separate them in the CZE mode, with relative standard deviations for migration times from 0.06-0.15% and for peak areas from 4-8%. The limits of detection were 1.3 mg l(-1) Sr2+ and 0.12 mg l(-1) Li+. The developed method was applied to the analysis of a surface sea water sample and a sea water reference material. The results were in good agreement with those obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and electrothermal atomic absorption spectrometry (ET-AAS).

Electrophoresis↗
PubMed2002

Strontium-89: a novel treatment for a case of osteosclerotic myeloma associated with life-threatening neuropathy.

Osteosclerotic myeloma is a rare disorder characterized by paraproteinaemia and osteosclerosis, and may be associated with a progressive peripheral neuropathy. Patients with widespread osteosclerotic lesions can succumb from neurological complications despite systemic chemotherapy. We present a case of disseminated osteosclerotic myeloma associated with POEMS (peripheral neuropathy, organomegaly, endocrinopathy, M band, skin changes) syndrome, which was complicated by a rapidly progressive, life-threatening neuropathy. The patient's symptoms remained unchanged in the face of combination chemotherapy. However, a substantial improvement was seen following outpatient treatment with the commonly available radioisotope strontium 89 in combination with steroids.

Anti-Inflammatory Agents↗