Electroencephalographic correlates of neurological disturbances at remote periods of the effect of ionizing radiation (sequelae of the Chernobyl' NPP accident).

The psychoneurological status of 40 participants (all men aged 25-45 years, official dose 15-51 rem) in the liquidation of the consequences of the accident at the Chernobyl Nuclear Power Plant in 1986-1987 was investigated; EEG mapping and three-dimensional localization of the sources of epileptic activity as compared with the data of healthy individuals (20 individuals) was carried out. Vegetative-vascular symptomatology was identified in the neurological status of all the patients; disseminated organic neurological symptomatology and endocrine disturbances were additionally identified in some of the patients. There were paroxysmal attacks periodically in the overwhelming majority (68%) of the patients; this correlated with the presence in the EEG of epileptic forms of activity. The patients were divided into two groups on the basis of the character of the EEG. Patients in whom slow alpha waves and waves of the theta range with a "focus" in the central-frontal regions of the cortex were recorded were included in group I (25 individuals). Analysis of the localization of the sources of epileptic activity revealed placement at the midline level in them with marked compactness and displacement of the focus to the right hemisphere. In the patients of group II (15 individuals), slow waves of frontal localization and diffuse beta waves predominated in the EEG in the presence of a reduction in the level of biopotentials. The localization of equivalents of epileptic activity was more diffuse in character and was at the basal level, with a greater representation of the sources of epileptic activity in the left hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

[The electroencephalographic correlates of neurological disorders in the late periods of exposure to ionizing radiation (the aftereffects of the accident at the Chernobyl Atomic Electric Power Station)]. / Elektroéntsefalograficheskie korreliaty nevrologicheskikh narushenii v otdalennye sroki vozdeistviia ioniziruiushchei radiatsii (posledstviia avarii na Chernobyl'skoi AES).

EEG mapping and three-dimensional localization of epileptic activity sources together with a neurological analysis were carried out in subjects having taken part in 1986-1987 in the liquidation of consequences of the Chernobyl accident. Experimental group included 40 right-handed 25-45 years-old men having received a radiation dose of 15-51 Ber stated officially. Control group consisted of 20 healthy men. Neurological examination of the patients revealed vegetative-vascular and endocrine dysfunctions as well as diffuse neurological symptoms. EEG of one group of patients (25 persons) was characterized by slow alpha- and theta-band foci and epileptic waves in the central-frontal regions; epileptic sources were localized at the diencephalic level mainly in the midline being shifted to the right hemisphere. In the EEG of another group (15 persons) delta-waves were recorded in the frontal regions at the background of diffuse beta-activity. The sources of epileptic activity of a diffuse character were localized at the basal level of the brain and in the cortex (predominantly) in the left hemisphere. The results obtained together with SPECT mapping and CT data permit to suppose the organic damage of different brain structures (at the cortical and the midline levels) in the patients, with participation of diencephalic structures in the pathological process hypothalamic-hypophysial system being probably connected with adaptive processes in the CNS.

[The late sequelae of radiation exposures on the neurological status of the body (clinico-experimental research)]. / Otdalennye posledstviia radiatsionnykh vosdeistvii na nevrologicheskii status organizma (kliniko-éksperimental'noe issledovanie).

It was found out in experiments on monkeys that one of the most serious remote consequences of small and medium doses of ionizing radiation was the development of stable organic disorders in various cerebral structures. Clinical researches substantiate the necessity to make registration of post-radiation pathological changes in central nerve system of patients.

[Radiation safety in space flights in the Intercosmos program]. / Problema radiatsionnoi bezopasnosti kosmicheskikh poletov v programme "Interkosmos".

This paper reviews the basic stages in the development of radiation safety of space flights within the framework of the Intercosmos program, including ground-based experiments on charged particle accelerators and gamma-emitters and actual flight studies onboard biosatellites and orbital stations. The paper also discusses norms and standards of radiation safety as related to flights of varying duration. It emphasizes the contribution made by Intercosmos cooperative projects into the development of space flight radiation safety parameters adopted as standards by the USSR Standardization Committee.

[Incidence of morphologic changes in cerebral cortex neurons of the rat exposed to accelerated carbon ions]. / Issledovanie chastoty morfologicheskikh izmenenii v neironakh kory golovnogo mozga krys pri vozdeistvii uskorennykh ionov ugleroda.

Structural lesions in neurons of the brain cortex of rats were investigated 1 and 3 months after their exposure to accelerated carbon ions with the energy 320 MeV/nuclon 10(4) particles/cm2 (LET = 120 MeVcm2/g) as well as to gamma-radiation in the dose 1.0 Gy. The irradiated animals showed morphofunctional, dystrophic and reparative lesions in neurons. The rats exposed to carbon ions developed more distinct changes that the animals exposed to gamma-radiation. It is postulated that similar fluxes of cosmic radiations will not produce a deleterious effect on the integrative functions of the central nervous system of cosmonauts.

[Radiobiologic basis of the quality factor of protons and helium ions]. / K radiobiologicheskomu obosnovaniiu faktora kachestva protonov i ionov geliia.

Reported data and experimental results of measuring the relative biological effectiveness of protons of different energies and helium ions of 4 GeV/nuclon were analyzed to determine quality factors of the major components of cosmic radiations. It is recommended to use quality factors equal to 1.30-1.45 for 100-730 MeV protons and equal to 1.75 for 9 GeV protons and 4 GeV/nuclon helium ions. It is also suggested to employ them as standards for solving practical problems of radiation safety in space flights.

Electrophoretic mobility of erythrocytes exposed to accelerated helium nuclei or to gamma-rays, as modified by adeturone.

The electrophoretic mobility of human erythrocytes exposed in whole blood or in cell suspensions to relatively low doses (0.7-2.5 Gy) of accelerated helium nuclei (4.6 GeV/nucleon) or of gamma-rays was found to diminish with increase in radiation dose, as measured at 3 h post-irradiation. Pre-treatment with a radioprotectant, adeturone (S-2-aminoethylisothiuronium adenosine-5'-triphosphate), allowed electrophoretic mobility to be maintained within normal limits, with more stable values in the case of alpha-irradiations. The experimental evidence is discussed in terms of the protectant's involvement in repair of radiation-induced conformational changes in surface membrane components.

[Frequency of chromosome disorders occurring in human lymphocytes in the in vitro exposure to different doses of deuterons as protected by adeturon]. / Issledovanie chastoty vozniknoveniia khromosomnykh narushenii v limfotsitakh cheloveka pri vozdeistvii in vitro razlichnykh doz deitronov pod zashchitoi adeturona.

Peripheral blood of 4 healthy donors was exposed to deutrons with the energy 4,2 GeV/nuclone and the intensivity of 4 to 6.10(10) particles per impulse, the capacity of the dose being 0,008 Gr/sec. The LPE of deutrons was 2,14 MeV sm2/g. Irradiation doses were 0,26; 0,49; 0,97; 2,02; 3,80 Gr. 15-20 min prior to irradiation, the protector adeturone was added at a concentration of 550 micrograms/ml of blood. Chromosome aberrations were analyzed in protected and unprotected blood samples. The results were treated using the method of variance and regression analysis. The correlative correspondence between the number of chromosome aberrations and an approximate dose of actual irradiation was established as Y = 0,13 d + 6,55.10(-4) D2 for dicentrics and as 0,26 D + 12,6.10(-4) D2 + 4,5 for the total percentage of aberrations. The pattern of the dose - effect dependence was retained in protected samples. The calculated values of the factor of dose decrease confirmed antiirradiation properties of adeturone.

[Effect of radiations with varying linear energy transfer on the skin of mice]. / Deistvie na kozhu myshei izluchenii s razlichnoi lineinoi peredachei énergii.

Experiments were carried out to measure the time and severity of the radiation reaction of the skin of mice exposed to X- and gamma-radiations, protons with energies of 645 and 50 MeV as well as accelerated helium ions at doses of 200 to 4000 rad. It was found that relative biological effectiveness coefficients of 645 and 50 MeV protons were 1.0 and those of helium ions were 1.3 for the skin reaction at early and late stages of observation. No significant difference in the time of manifestation of radiation-induced skin lesions as related to radiations with various LET was detected.

[Action of protons with 25 and 50 MeV energies on the chromosomes of human peripheral blood lymphocytes in vitro]. / Deistvie protonov s énergiei 25 i 50 MéV na khromosomy limfotsitov perifericheskoi krovi cheloveka in vitro.

The frequency and type of chromosomal abberations in human lymphocytes induced by 25, 50, 645 MeV protons and 200 kv x-rays were studied. It was shown that the yield of one-hit acentric fragments increased linearly and that of double-break aberrations increased exponentially with the irradiation dose. It was demonstrated that under the influence of radiations with high linear energy transfer the number of paired fragments increased and that of dicentrics and rings decreased. The test of total yield of chromosomal aberrations and their specific types helped to derive coefficients of relative biological effectiveness of the above irradiations. There was a quantitative correlation between the dose and yield of individual aberration types. This suggests that lymphocytes can be used as a biological dosimeter for dose measurement.

[Harmful action of radiations with different linear energy losses on the nerve cells of the rat cerebellum]. / Issledovanie povrezhdaiushchego deistviia izluchenii s razlichnymi lineinymi poteriami énergii na nervnye kletki mozzhechka krys.

The damaging effect of 25 and 50 Mev protons, X-rays and Co60 gamma-rays on the cerebellar cells of rats of early postnatal period was studied. Radiosensitivity of neurons of different compartments of the cerebellar cortex varied significantly. Radiosensitivity of the inner and outer granular layers of the cerebellum to irradiation with 25 Mev protons was similar.

Influence of heavy ions on the transforming activity of DNA.

Changes in functional activity following treatment of DNA with heavy ions were analysed by transformation assay. Biological response to exposure to charged particles, 10B, 12C, and 22Ne, was evaluated by the extent of inactivation of ability of DNA to transfer the genetic marker of tryptophane independence. The possibility of protecting the biological activity of DNA was studied using a conventional protector, cysteamine hydrochloride, or the preparation cytriphos, synthesized at the Institute of Radiobiology and Radiation Hygiene, Sofia. Dried samples of donor DNA isolated from a Bacillus subtilis prototroph strain were exposed to doses of 50 krad to 1 Mrad. For the three types of charged particles used, dose response of the inactivation process was defined by an exponential function. Comparison of response curves for the three types of radiation showed the effect to be dependent on LET, being highest for 10B and lowest for 22Ne. In all three cases, addition of a protective substance failed to produce any change in the biological effect observed.