Silicon and phosphorus contents in polished and unpolished rice planted on a district of high incidence of amyotrophic lateral sclerosis (ALS) have been determined by neutron activation and X-ray fluorescence methods, and compared with those from control areas. In the neutron activation analysis, β-ray spectra of32P produced by the31P (n, γ) 32P reaction on polished and unpolished rice were measured with a low background β-ray spectrometer. In the X-ray fluorescence analysis, characteristic X-rays were analyzed with a wavelength dispersive X-ray fluorescence spectrometer. Silicon contents in polished and unpolished rice from the ALS area are 42 μg·g-1and 370 μg·g-1, respectively, and the corresponding phosphorus contents are 1210μg·g-1, and 3 370μg·g-1, respectively. The data for ALS area are equal to those for the control area within standard deviation.
CA 19-9 epitope (s) on carcinoembryonic antigen (CEA) was studied by a method designated the hybrid immunoradiometric-assay (hybrid IRMA) using solid phase CEA antibody as a capture of CEA molecule and radio-labeled NS 19-9 antibody as a detector. The radioactivities of the hybrid IRMA of respective sera with certain cancers differed from that of normal sera. The specific radioactivities of hybrid IRMA were not disappeared by washing with the reaction mixture containing Triton X-100 as a detergent. Treatments of the sample with neuraminidase or periodate diminished the specific bound radioactivities, like as a CA 19-9 antigen. Furthermore, the treatment of CEAs by PI-PLC had no effect to the radioactivities. Taken together, it was suggested that CEA sugar moieties contain CA 19-9 like epitope (s) .
A lead-shielding was constructed for a welltype Ge detector to utilize low-level r spectrometry. Background counting rate was investigated under lead thickness of 5-25 cm. It has been confirmed that selection of low activity materials for the construction of the detector has advantage to reduce the contribution of background deu to natural radioactivities. N2gas was helpful to reduce the contribution of atmospheric radon daughters especially during ofd ventilation period.