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In the departments of nuclear medicine, patients are treated with relatively large activities of (131)I for therapeutic purposes. The applied activities are in the range of 200-10 000 MBq. Consequently, individuals situated in the dwellings of the patients dismissed from the hospital are subjected to an external as well as an internal radioiodine exposition. Internal exposition is due to the inhalation of (131)I exhaled by the patients. In this article, the measurements of radioactivity exhaled by patients with various thyroid diseases, treated with (131)I in the department of Nuclear Medicine of the Radiological Centre in Goettingen and in the Hospital of Nuclear Medicine in Wuerzburg are presented. The measurements of activities exhaled by patients were repeated daily, up to 25 d after the treatment. In addition, the residual activities were monitored by measuring the external dose rates, and by measuring the (131)I activity in the urine of these patients. In some cases, the exhaled radioiodine was separated into three fractions: the elemental, the organically bound and the aerosol-bound iodine fraction. On the basis of the proposed measurements, the doses received by the family members of a discharged patient treated with (131)I were estimated by a model calculation.

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A survey of a CLINAC 2100 C medical accelerator showed residual short half-life radiation after switching off the accelerator. This led to a dose of radiation for the medical employees when the patient was handled. The dose rate was measured with a dose rate meter FH40G, and annual dose for an assistant medical technician (AMT) was estimated under conservative conditions. In the assumed situation of 1000 patient treatment fractions with high-energy photons, an AMT would get an annual dose of 960 muSv, while the monthly dosimeter records would show zero, if the dose received is below threshold of 100 muSv.

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The fraction of the positively charged unattached radon decay products, 218Po and 214Pb in indoor air was determined by model calculations. The results of the calculations were confirmed by measurements in a test chamber (volume: 8 m3). The fraction of both radionuclides depends on the attachment parameter (S(1)) and the neutralisation rate (nu) in room air. The total removal parameter S1 = lambda1 + v + q(f) + X = lambda1 C1f/C0 considers the attachment rate to aerosol particles (X), plate-out rate to room surfaces (q(f)) and the ventilation rate (nu) (lambda1: decay constant of 218Po). The S1-value of room can be determined by measurement of the concentration of the unattached 218Po clusters (C1f) and radon (C0). The neutralisation rate (nu) in environmental air depends mainly on the ion production rate. The influence of the relative humidity in the range 30-95% (temperature: 20 degrees C) is negligible. In addition, equal neutralisation rates for 218Po and 214Pb could be derived. In room air with ion production rates between 5 and 500 nC kg(-1) h(-1) mainly generated by the alpha emitters of radon, thoron and their short-lived decay products, the fractions for positive 218Po clusters vary between 55 and 17% and for 214Pb clusters between 53 and 14%. For a typical average concentration of radon (50 Bq m(-3)) and thoron (10 Bq m(-3)) in homes, 48% of 218Po clusters and 45% of 214Pb clusters are positively charged.

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The monitoring of radon exposure at workplaces is of great importance. Up to now passive measurement systems have been used for the registration of radon gas. Recently an electronic radon gas personal dosemeter came onto the market as an active measurement system for the registration of radon exposure (DOSEman; Sarad GmbH, Dresden, Germany). In this personal monitor, the radon gas diffuses through a membrane into a measurement chamber. A silicon detector system records spectroscopically the alpha decays of the radon gas and of the short-lived progeny 218Po and 214Po gathered onto the detector by an electrical field. In this work the calibration was tested and a proficiency test of this equipment was made. The diffusion behaviour of the radon gas into the measurement chamber, susceptibility to thoron, efficiency, influence of humidity, accuracy and the detection limit were checked.

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This article investigates the effects of di-n-octyl tin dichloride (DOTC) on some morphologic changes in spleen and thymus as well as on the immune reaction of rats. One i.v. injection of DOTC in a dose of 4 mg/kg led in female rats to an atrophy which was reversible within six weeks, and to cell depletion of the thymus. The time needed for the regeneration (the thymus indicated a dose-dependency of the action of DOTC (4-12 mg/kg) on these morphologic changes, which was established by examining immunostimulated rats. Changes in the spleen were observed only with extremely high doses of DOTC. The action of DOTC after one or repeated immunization of rats erythrocytes taken from sheep, on the daughter-cell-dependent production of antibodies was examined by means of an immuno-rosette-test and by determining the hemagglutination titre. The number of lymphocytes in the spleen which form rosettes was reduced after one intravenous administration (4 mg/kg) of DOTC 1, 2, 3, or 8 d prior to antigenic stimulation. The time needed to form rosettes was dependent on the dose. The immunoglobulin-G-immunoglobulin-M antibody titre remained unaffected if DOTC was given once by i.v. injection 7 or 8 d prior to immunostimulation, the doses ranging from 4 to 12 mg/kg. DOTC-treatment carried out twice with 4 mg/kg led to a complete suppression of the immunoglobulin-G/immunoglobulin-M antibody production against erythrocytes taken from sheep, if DOTC had been applied on eight consecutive d and on d 0 (the d of the primary immunization).(ABSTRACT TRUNCATED AT 250 WORDS)

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Antisera produced in rabbits against Triton X-100 solubilized human erythrocyte ghosts formed several several precipitation lines in immunoelectrophoresis and immunodiffusion tests against the solubilized ghosts. The antisera were used for detecting several membrane components during chromatographic separation. A membrane component was partially isolated using gel filtration on SEPHADEX G-200 (fraction F1/F2). Spectrin (Tektin A) was shown to be the main moiety of these fractions. Associated proteins (haemoglobin, GAPD) could not be detected by the antisera against whole ghost solubilisate.

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