Sorption of two alpha nuclides, 237Np and239Pu, on granite was studied by the autoradiographic method using a solid state track detector (CR-39) . The autoradiographs for the surface of rock thin sections of the Inada biotite-granite which were immersed for 48 h in the ground-water containing both nuclides, showed that the alpha nuclides sorbed preferentially on biotite rather than on quartz and feldspar. Mechanism of the alpha nuclides sorption on granite was discussed based on the results of optical microscopic observations of the thin section, track density measurements and alpha-ray spectrometry. It was considered that the ion exchange seems to be a major mechanism of the sorption of these nuclides on the granite.
Chitosan derived from chitin which is a cellulose-like biopolymer distributed widely in nature, especially in shellfish, insects, fungi and yeast, is known to be one of the natural chelating agents. The purpose of the present study is to investigate whether chitosan can be applied to the animal and human body in order to reduce the bioavailability of radiostrontium in foods. Chitosan solution was orally given and immediately after then85SrCl2was administered to rats using a stomach tube. The whole-body retention of85Sr determined by in vivo counting was lower than that of control rats which were not given chitosan. The activity ratio in urine and f eces f or chitosan-treated rats was higher than control rats. Ten percent of alginate food was given to rats during 10 days and85Sr was administered orally. The whole-body retention of85Sr alginatetreated rats was decreased sharply compared with control rats. These results suggested that chitosan and alginate can be used as a drug to reduce bioavailability from gastrointestine of ingested radio strontium.
An anticoincidence shielding has been developed for a low-background well-type Ge detector. The detector in a heavy lead shielding was surrounded by plastic scintillators to reduce background produced by cosmic rays. Background counting rate in the energy range 40 keV to 3 MeV was reduced to 1/2.2 at anticoincidence mode. An example of low-level γ spectrometry utilizing this detector assembly is given.
We measured serum and urinary concentrations of type IV collagen by radioimmunoassay (RIA) in patients with renal diseases and compared them with normal levels. In diabetics with macroproteinuria or with renal insufficiency, serum and urinary concentrations of type IV collagen were higher than in diabetics without nephropathy or with early renal damage as determined by the presence of microproteinuria. Serum concentrations of type IV collagen in patients with membranous nephropathy (MN) showed a significant increase compared with normal controls. Urinary concentrations of type IV collagen in patients with MN, minimal change nephrotic syndrome at the remission phase and nephrotic phase and IgA nephropathy showed a significant increase compared with normal controls. These increases may indicate that a change in basement membrane metabolism has occurred in these renal diseases.