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Most patients with bony metastases experience painful symptoms. Strontium-89 isotope therapy is an alternative to traditional hemibody radiation in cases of multiple, diffuse metastases. Generally given as a single i.v. slow-push infusion, relief begins in one to three weeks, peaks at six weeks, and has a mean duration of 12 months. Up to 22 percent of patients are pain-free at three months.
We report initial 87Sr/86Sr values from an Upper Proterozoic carbonate succession from Svalbard and East Greenland. This succession, now tectonically separated into three sequences, is thick, relatively continuous, and well preserved. The relative ages of the samples from within the basin are well constrained by litho-, bio-, and chemostratigraphic techniques. The data from this study and related data from the literature are used to construct a curve of 87Sr/86Sr for Upper Proterozoic seawater. The new data reported in this study substantially improve the isotopic record of Sr in seawater for the period between 650 and 800 Ma. The data indicate that delta 87Sr values of seawater were variable but low (delta 87Sr approximately -500 to -250) between 900 and 650 Ma, and rose rapidly to approximately +30 by 600 Ma. The range of variation of delta 87Sr in seawater during the Riphean-Vendian exceeds the entire range of delta 87Sr in seawater during the Phanerozoic. While variation in the average isotopic composition of Sr delivered to the oceans by rivers can account for some of the observed range, changes in the ratio of submarine hydrothermal flux to river water (continental) flux are responsible for the large variation in seawater Sr isotopic composition. Changes in the continental flux of Sr to the oceans can be related to tectonic factors. Large changes in the hydrothermal flux to river water flux ratio indicated by the data could have significant consequences for the chemistry of the ocean-atmosphere system.
Serial 87mSr bone scintigrams were performed on a series of patients being treated by cyclical combination chemotherapy for metastatic breast cancer. All the patients investigated responeded to the chemotherapy, but initially the scintigrams showed an apparent deterioration, in that the tumor-to-normal isotope uptake ratios increased. Following this initial "flare" the scintigram appearance improved with a decrease in the tumor-to-normal uptake ratio. It is suggested that deterioration in the scintigram in the early stages of treatment should not be regarded as an indication that the patient is failing to respond.
The CI meteorites are rare but important objects because they may represent our best sample of chemically unfractionated Solar System material. Despite the fact the these meteorites apparently retain their original chemical composition, they clearly contain secondary mineral phases, some at least believed to have been produced through the action of liquid water on the parent body. The timing of this event, however, was unknown. In an attempt to solve this problem, we have measured the Sr isotopic composition and 87Rb/86Sr in carbonates and sulphate separated from the Orgueil meteorite. Both of these phases probably precipitated from aqueous solution. Our first results, reported here, show that carbonate deposition occurred contemporaneously with parent body formation or shortly after it probably within 100 Myr. On the other hand, at least some of the calcium sulphate seems to have been formed recently.
In spite of increasing efforts to reduce nitrogen inputs into groundwater from intensive agriculture, nitrate (NO3) remains one of the major pollutants of drinking-water resources worldwide. Determining the source(s) of NO3 contamination in groundwater is an important first step for improving groundwater quality by emission control, and it is with this aim that we investigated the viability of an isotopic multi-tracer approach (delta15N, delta11B, 87Sr/86Sr), in addition to conventional hydrogeologic analysis, in two small catchments of the Arguenon watershed (Brittany, France). The main anthropogenic sources (fertilizer, sewage effluent, and hog, cattle and poultry manure) were first characterized by their specific B, N and Sr isotope signatures, and compared to those observed in the ground- and surface waters. Chemical and isotopic evidence shows that both denitrification and mixing within the watershed have the effect of buffering NO3 contamination in the groundwater. Coupled delta11B, delta15N and 87Sr/86Sr results indicate that a large part of the NO3 contamination in the Arguenon watershed originates from the spreading of animal manure, with hog manure being a major contributor. Point sources, such as sewage effluents, contribute to the NO3 budget of the two watersheds.
1. Radiocalcium absorption was measured in duplicate in 10 subjects by the double-isotope method, with calcium as the oral carrier (2.5 mmol). Analysis of variance gave 95% confidence limits for a single measurement of fractional absorption and maximum absorption rate in a given individual of +/- 16.5% of administered dose and +/- 18.2% of dose/h respectively. 2. The size of these within individual variations suggests that alterations in the rate of calcium absorption may contribute to the week-to-week stabilization of some other controlled variable, such as plasma concentration of calcium. 3. In six of the subjects, calcium absorption was also measured with calcium loads at concentrations of 0.5, 5.0 and 20 mmol. Significant falls in fractional absorption, maximum absorption rate and mean transfer rate occurred as the load increased, together with a rise in mean transit time. Although between-individual differences at a given load were considerable, given a single-test result with a known carrier load, it is possible to predict quite accurately the results which would be obtained if a different carrier load were to be given.
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