[en] Dose size for quantifying stochastic effect from which hazard factors are derived, does not suffice; individual or collective predispositions must be considered, too. This is indicated by the difference of the natural incidence of malignant diseases in Hiroshima and Nagasaki. Inclusion of hazard factors in the formula of effective equivalent dose appears to pose some problems. (DG)

[en] Organ and tissue doses outside of focus volume were calculated for their occurrence under radio therapy conditions. Organ-specific hazard co-efficients can be deduced from data of the incidence of secondary tumours obtaining in the irradiation of Bechterew's disease and from the data of calculated organ doses, and can be compared with the corresponding results of other epidemiological studies. Based on the hazard co-efficients obtained, it is possible to assess the risk of stochastic delayed damage occurring after radio therapy. Irradiation of a low abdominal tumour was selected for matters of exemplification. (orig./DG)

[en] It seems that a sizeable portion of the malignant thyroid tumors diagnosed after previous irradiation to a certain extent reflect the prevalence of nonchirical thyroid cancer in the general population. Thyroid carzinogenesis has been extensively studied in animals. Major experience with radiation-induced thyroid cancer stems mainly from the population of Hiroshima and Nagasaki. To date three different population have been studied after exposure to J-131 from fallout (low-level-radiation). (DG)

[en] Thorotrast is an X-ray contrast medium for use in angiography and consists of a colloidal dextrin-stabilized 25%-thorium-dioxide solution. The results obtained allow to make some propositions concerning the hazards of radiation-induced carcinogenesis in liver, spleen, muscular connective tissue, lungs, bone marrow, marrow-free bones and kidneys. (DG)

[en] Rats were exposed to Ru 222-concentrations of 1.073 x 10³ Bq/l under constant environmental conditions in order to establish a correlate for increased corticosterone production. The radiation dose was studied which accumulated in the suprarenal glands or in a number of other organs during exposure time. Examination showed a statistically significant increase of liposome volume and of mitochondriac internal membrane surface where both adenosine triphosphate production and corticosterone synthesis are localized. (DG)

[en] A prolonged stage of radiation sensitivity results for the development of the brain and the nervous system from the fact that man has a relatively long fetal period. Even with doses down to 0.2 to 1 Gy, later development is dominated by this fact particularly between the 10th and 18th pregnancy week. There seems to be a high sensitivity to the induction of malignant changes. Infantile induction rate for leukaemia is increased. (DG)

[en] The question has to be examined from a medical point of view whether or not the additional diseases of breast cancer and leukaemia as well as genetic effects are exclusivley due to the impact of ionizing radiation or whether or not additional noxae like drugs or non-malignant tissue changes as cofactors enhance the assumed carcinogenic effect of radiation. An analysis of literature showed that additional epidemiological studies on stochastic radiation effects are needed in order to confirm the actual rise level of radiation exposure. (DG)

[en] Exemplified by chronic irradiation of dogs, it could be shown that haemocytogenesis is maintained. There are some signs in the blood picture indicating increased cell turnover through increased formation in the bone marrow. Readjustment to increased blood cell production levels is accompagnied by changes in humoral regulation factors. Concerning the issue of the pathogenesis of late sequelae, special attention should be given to the miro-ecology of the stem-cell storage tissue. (DG)

[en] Damage which was caused in the genetic substance (DNA) through radiation or certain chemical noxae, can be repaired. As a rule, there are several repair systems in the cells which have different modes of action. Gene mutations are not generally the result of absorbed radiation but the result of deficient repair processes. Cellular repair systems represent a complicated network in which certain repair enzymes participate in various repair processes. Concentration of repair enzymes may vary in certain instances. (DG)

[en] DNA excision repair constitutes the most important DNA repair system. DNA modifications may be induced even during the course of DNA replication of semiconservative DNA synthesis. All repair processes occur in almost every cell; however, juvenile cells have higher enzyme activities than completely differentiated mature cells. DNA errors or defects result in chromosome aberrations, sister chromatid exchanges, mutations, transformations and in carcinogenesis. Repair processes have a special significance for persons living in areas of elevated environmental radio-activity or for those with an occupational exposure to a certain radiation level. This is why the staffs of the Gasteiner Heilstollen and of the Seibersdorf Research Centre were examined. The paper briefly reports the results obtained. (DG)