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Telemetry was used to examine spawning migration of sea trout, Salmo trutta L. ( n = 126), in two rivers in northern Sweden. The spawning areas defined by radio-tagged fish differed between the river systems. In the River Vindelälven, sea trout spawned in the main stem and 80% of tagged individuals returned to areas where hatchery-reared juveniles had been previously stocked. In the River Piteälven, 74% of tagged sea trout ascended tributaries for spawning. Tagged fish were categorised into three groups of migratory pattern. (classification and regression tree) analysis indicated that distance from tagging location to spawning site ( S) explained the migratory patterns. Large S separated fish with stepwise upstream migration from those with up- and downstream migrations and one-directional direct migration. Fish tagged early in the season migrated the longest distance to spawning areas. Stocking locations and sex explained the large search behaviour up- and downstream in the rivers. The findings are important for the sustainable management of sea trout in the Gulf of Bothnia. [ABSTRACT FROM AUTHOR]

Advances in diagnostics and targeted radionuclide therapy of haematological and neuroendocrine tumours have raised hope for improved radionuclide therapy of other forms of disseminated tumours. New molecular target structures are characterized and this stimulates the efforts to develop new radiolabelled targeting agents. There is also improved understanding of factors of importance for choice of appropriate radionuclides. The choice is determined by physical, chemical, biological, and economic factors, such as a character of emitted radiation, physical half-life, labelling chemistry, chemical stability of the label, intracellular retention time, and fate of radiocatabolites and availability of the radionuclide. There is actually limited availability of suitable radionuclides and this is a limiting factor for further progress in the field and this is the focus in this article. The probably most promising therapeutic radionuclide, 211At, requires regional production and distribution centres with dedicated cyclotrons. Such centres are, with a few exceptions in the world, lacking today. They can be designed to also produce beta- and Augeremitters of therapeutic interest. Furthermore, emerging satellite PET scanners will in the near future demand long-lived positron emitters for diagnostics with macromolecular radiopharmaceuticals, and these can also be produced at such centres. To secure continued development and to meet the foreseen requirements for radionuclide availability from the medical community it is necessary to establish specialized cyclotron centres for radionuclide production. [ABSTRACT FROM AUTHOR]

Objective: To investigate the elimination of stabilised hyaluronan following intra-articular injection into the knee joint.Design: This was a single-centre, single-dose study in healthy human volunteers.Participants: Six healthy men, aged 28 to 47 (mean 38) years, were enrolled in the study.Methods: Subjects received a single intra-articular injection (3ml; 20 mg/ml) of (131)I-labelled non-animal stabilised hyaluronic acid (NASHA). Radioactivity in the knee, blood, urine and over the liver was measured with gamma counters for 3 weeks post-injection; magnetic resonance and gamma camera imaging of the knee were also performed at 24 hours post-injection. Radioactivity uptake data were tested for conformity of fit to different mathematical models.Results: Elimination of (131)I-labelled NASHA from the knee was characterised by a fast initial phase and a slow late phase, and conformed to a three-exponential-function model with elimination half-lives of 1.5 hours, 1.5 days and 4 weeks. Radioactivity distribution within the knee joint was homogenous, and no local leakage was observed. Hepatic radioactivity uptake was low, but significantly above background levels, for the first 2 days post-injection, before declining to background levels. Visual imaging indicated an increase in intra-articular fluid volume at 24 hours post-injection.Conclusions: The elimination kinetics of (131)I-labelled NASHA from the human knee joint were described by three distinct phases, with half-times of 1.5 hours, 1.5 days and 4 weeks. Most likely, the last value reflects the true half-life of NASHA following intra-articular injection since the labelling method used causes minimal modification of hyaluronan. [ABSTRACT FROM AUTHOR]

Four patients with radiologically normal pituitary gland were examined with positron emission tomography after the administration of (methyl-C)-L-methionine. On a following day the examination was repeated with (methyl-c)-D-methionine. The accumulation rate of L-methionine in the pituitary was measured, giving a value that was about twice that of normal brain tissue. The accumulation rate of D-methionine in the pituitary was almost a factor of 10 lower than that of L-methionine. In the normal brain tissue that ratio was 2.3. The study clearly indicates that the methionine uptake in the pituitary is stereospecific. C-D-methionine is freely distributed in the tissue without entrapment, whereas C-L-methionine is irreversibly bound. It is concluded that PET with C-L-methionine can be used to study amino acid utilization in the pituitary. [ABSTRACT FROM AUTHOR]