Childhood leukemia in Belarus before and after the Chernobyl accident

Childhood leukemia (ICD 204-208 [1]) incidence rates in the different regions of Belarus are reported for a period before and after the Chernobyl accident (1982-1994). There are, at this point, no recognizable trends towards higher rates.     

Further evidence for elevated human minisatellite mutation rate in Belarus eight years after the Chernobyl accident

Analysis of germline mutation rate at human minisatellites among children born in areas of the Mogilev district of Belarus heavily polluted after the Chernobyl accident has been extended, both by recruiting more families from the affected region and by using five additional minisatellite probes, including multi-locus probe 33.6 and four hypervariable single-locus probes. These additional data confirmed a twofold higher mutation rate in exposed families compared with non-irradiated families from the United Kingdom. An elevated rate was seen at all three independent sets of minisatellites (detected separately by multi-locus probes 33.15, 33.6 and six single-locus probes), indicating a generalised increase in minisatellite germline mutation rate in the Belarus families. Within the Belarus cohort, mutation rate was significantly greater in families with higher parental radiation dose estimated for chronic external and internal exposure to caesium-137, consistent with radiation induction of germline mutation. The spectra of mutation seen in the unexposed and exposed families were indistinguishable, suggesting that increased mutation observed over multiple loci arises indirectly by some mechanism that enhances spontaneous minisatellite mutation.     

The dynamics of thyroid diseases in the inhabitants of Kiev and Kiev Province after the accident at the Chernobyl Atomic Electric Power Station

Autoimmune affections of the thyroid gland were found to be on the increase as were Hashimoto's disease and follicular adenoma, as evidenced by a pathomorphic study in surgically removed thyroid glands of 12684 patients over 1984-1993. Rise in the frequency of malignant tumors was moderate. Increase in the incidence of papillary microcarcinoma against the background of another surgical pathology of the thyroid gland may be an unfavourable prognostic sign of further growth of morbidity of clinically manifest forms of carcinoma in Kiev and the Kiev Province.     

Pediatric thyroid cancer after the Chernobyl disaster. Pathomorphologic study of 84 cases (1991-1992) from the Republic of Belarus

BACKGROUND: During the initial period after the Chernobyl accident, large amounts of radioactive iodine were released in fallout, resulting in serious exposure to the thyroid gland in the residents of areas around the nuclear power station. Beginning in 1990, a definite increase in the incidence of thyroid cancer was noted in children of the Republic of Belarus. METHODS: Morphologic and clinical features of 84 cases of post-Chernobyl thyroid carcinoma in Belarussian children from 5 to 14 years of age are reported. The latent period for tumor development was 4-6 years, with a mean of 5.8 years. RESULTS: Papillary carcinoma was found in 83 patients and medullary carcinoma in one. Besides typical papillary carcinoma (14%), solid (34%), follicular (33%), mixed (10%), and diffuse sclerosing (9%) variants were observed. The follow-up period ranged from 8 months to 2.5 years. One patient died, local recurrence developed in 2, and cervical lymph node metastases developed in 10. To date, the incidence of local recurrence or metastatic disease after surgery was significantly higher in patients 5-8 years of age and in residents of areas nearest to the Chernobyl station. CONCLUSIONS: Post-Chernobyl pediatric thyroid carcinoma is characterized by a short latency, a higher proportion of tumors arising in young children, and an almost equal sex ratio. Microscopically, these tumors were usually aggressive, often demonstrating intraglandular tumor dissemination (92%), thyroid capsular and adjacent soft tissue invasion (89%), and cervical lymph node metastases (88%). Papillary carcinoma was diagnosed in 99% of cases, with an unusually high frequency of solid growth patterns. Morphologic changes in nonneoplastic thyroid tissue were present in 90% of the glands, and the most specific findings were vascular changes and perifollicular fibrosis.     

Management of 29 children with thyroid cancer following the Chernobyl accident]

As a consequence of the Chernobyl nuclear power plant accident, a considerable increase of thyroid cancer among contaminated children has been reported in Ukraine, Belarus and Russia. A group of 29 children aged from 5 months to 10 years (mean 4.7 years) at the time of the accident, with a papillary thyroid cancer, have been examined at the Pitié-Salpêtrière hospital in Paris. The cancer was discovered by systematic ultrasonography in only 25% of cases. No reliable dosimetric estimation was achieved. The initial surgical treatment was performed in Ukraine. Cervical lymph node and pulmonary metastases were present in 24 and 11 cases respectively. A complementary surgical treatment was necessary for 9 children and one to four radioiodine treatments were given to 24 children. With a mean delay of 7 years after the cancer discovery, an apparent cure or a remission was obtained for 20 children, 6 children have cervical lymph node metastases requiring a surgical treatment and 3 have evolving lung metastases. The management of the great number of foreseeable cases of thyroid cancer requires an improved systematic screening, a large number of rooms dedicated to high activity radioiodine treatments, funds for disposable material and training missions.     

Prevalence of thyroid autoantibodies in children and adolescents from Belarus exposed to the Chernobyl radioactive fallout

BACKGROUND: The long-term effects of ionising radiation, including radioiodine, on thyroid function are not well known. We compared thyroid immunity and function in two groups of children from Belarus, one of whom was exposed to the radioactive fallout of Chernobyl. METHODS: We measured serum free thyroxine 4 (free T4), free T3, and thyrotropin hormone (TSH) and the prevalence of thyroid autoantibodies (antithyroglobulin and antithyroperoxidase), in 287 children or adolescents living in Hoiniki (average caesium contamination of 5.4 Ci/km2). We also studied 208 children and adolescents living in Braslav (average contamination <0.1 Ci/km2), who were age 12 years or less at the time of the Chernobyl accident. FINDINGS: The prevalence of antithyroglobulin or antithyroperoxidase, or both, was significantly higher (p=0.0001) in individuals living in Hoiniki (56 [19.5%] of 287) than in those living in Braslav (eight [3.8%] of 208). In both villages, no sex differences were found in the antibody prevalence before age 13 years. Thereafter, a significantly higher prevalence of thyroid autoantibodies was found in girls from Hoiniki. The increase in the prevalence of circulating antibodies in the contaminated group was already apparent in individuals who, at the time of the accident, were in utero or newborn (15.7%), and was even more pronounced in children of 9 years or more (35.1%). No major alterations of serum FT-4, FT-3, or TSH were found. INTERPRETATION: 6-8 years after the Chernobyl accident, a significant increase in thyroid autoimmunity was found in children exposed to radioactive fallout. Pubertal age in girls is a risk factor for increased prevalence of thyroid autoimmunity. The autoimmune phenomena are limited to an increased prevalence of circulating thyroid autoantibodies without evidence of significant thyroid dysfunction. The future development of clinically relevant thyroid autoimmune diseases, especially hypothyroidism, is a possibility.     

Carcinoma of the stomach following the Chernobyl nuclear accident

Medical consequences of many nuclear accidents on humans are well studied, but the results pertaining to gastric cancer patients who were exposed to radiation as a result of the Chernobyl nuclear accident have not been analysed. In this study, the outcome of the surgical treatment of 68 gastric cancer patients who were exposed to radiation as a result of the Chernobyl nuclear accident was compared with that of 117 consecutive gastric cancer patients from uncontaminated areas of the Ukraine. Patients in the study group was significantly younger than that of the control group. Comparative analysis showed the same frequency of regional metastases (65.7% versus 71.1%, P > 0.05), but a smaller number of distant metastases (23.8% versus 38.1%, P < 0.05) in the study group. 41.2% of patients in the study group underwent total gastrectomy compared to 19.6% of patients in the control group (P = 0.002). Postoperative complications developed in 13.2% of patients in the study group, while postoperative mortality in the study group was 7.3% compared to 1.7% in the control group. A significant decrease in CD16 cells was noted in patients from the study group following the operative procedure. Young age, invasive tumours with smaller number of distant metastases, frequent necessity for total gastrectomy and combined operations with adjacent organs, a higher level of postoperative morbidity and mortality and low levels of natural killer cells (CD16+) with a tendency to decrease after surgery are characteristic of patients with carcinoma of the stomach affected by the Chernobyl accident.     

Cancer consequences of the Chernobyl accident in Europe outside the former USSR: a review

Therapeutic research is being stepped up to light Alzheimer's disease (AD), although its heterogeneity, the insufficiency of physiopathological knowledge, and the lack of a reference treatment impede the development of a drug to combat it. However, progress has opened up many avenues. Some recent approaches that have led to therapeutic research are identification of biochemical abnormalities, identification of dysfunction in several neurotransmitter systems (cholinergic, catecholaminergic, serotonergic, and peptidergic systems), and the study of senile plaques and neurofibrillary degeneration tangles. Although some types of therapy have been used for a long time (e.g., metabolic products such as nootropes), recently developed drugs target different systems: for example, neurotransmitter systems are important for symptomatic improvements in cognitive functions. The principal improvements expected with some new anticholinesterases whose role is to increase the available amount of central acetylcholine are in memory and attention. Second, retarding neuronal degeneration by acting on amyloid plaques is another possible future therapy. Here, protease inhibitors appear to be interesting tools. Third, the endototoxin etiology of neurodegenerative illnesses remains uncertain. After the first attempts with N-methyl-D-aspartate (NMDA) antagonists that had inescapable side effects, hopes rose with some new pharmacological tools such as the AMPA/kainate antagonists. Fourth, a possible stimulation of neuronal plasticity by neurotrophic factors such as nerve growth factor (NGF) constitutes another prospected research area. Fifth, the inflammatory aspects of degenerative diseases attract the attention of many laboratories and preliminary reports are hopeful. Finally, out of the established pharmacological tools, gene therapy, though still hypothetical, may become the expected treatment in the future. Pharmacotherapy used in the most common types of dementia has until now been largely palliative and dealt with symptoms. It is nonetheless not unreasonable to look forward to the development of drugs that will be able to combat the evolution of the dementia itself, rather than its symptoms. A list of different products developed to treat AD is concluded by an evaluation of the expected results and, in particular, the orientations likely to be necessary.     

Genetic disorders in house mice after the accident at Chernobyl power plant

Genetic effects were studied in house mice caught from 1986 to 1994 in regions polluted by radionuclides as a result of the Chernobyl disaster. The dose rates of gamma-radiation on the soil surface ranged from 0.02 to 200 mR/h. The frequency of reciprocal translocations in mouse spermatocytes was relatively low, but increased with the dose rate. Embryo mortality was increased only in the progeny of male mice caught in 1987 in the area with maximum contamination. The frequency of mice heterozygous for recessive lethal mutations decreased with the time after the accident.     

Radiocesium contamination in a submediterranean semi-natural ecosystem following the Chernobyl accident: measurements and models

Radiocesium dynamics in a Quercus conferta Kit ecosystem in Northern Greece have been extensively studied over the years 1993-1995. Radiocesium distribution in the different parts of the ecosystem was measured. A total 137Cs inventory of 243+/-66 MBq ha(-1) due to the Chernobyl accident was measured in all parts of the ecosystem. Almost 90% of this inventory is still in the upper layers of the soil and the forest floor. In particular 13.4% is in the forest floor, 52.6% in the Ah horizon, and 23.4% in the upper 5 cm of the soil. Only 2.2% of this inventory is in the above ground biomass. The mean total 137Cs deposited on the forest floor from the above ground biomass is 0.18 MBq ha(-1) y(-1). Cesium leaching from the forest floor is negligible. The radiocesium distribution in soil is fixed and in equilibrium, at least since 1993. Most of radiocesium is not available for migration. Cesium migration in soil was modeled by a) an "equivalent diffusion" model with different initial conditions and b) a "compartment" model derived from a diffusion-advection model. A compartment model for the contamination of living biomass is proposed. The total absorbed dose rate in air as well as the contribution due to 137Cs from the Chernobyl accident was determined inside the forest, by in-situ gamma spectrometry.     

The genetic sequelae for plant populations of radioactive environmental pollution in connection with the Chernobyl accident

Populations of Arabidopsis thaliana (L.) Heynh., and Pinus sylvestris L., growing within 30 km of Chernobyl and Bryansk region have been analyzed for the frequency of embryonic lethal mutations on Arabidopsis and frequency of chlorophyll mutations and chromosome aberrations by pine. On pine also have been analyzed rate of mutations at enzyme loci in endosperms of seeds. Dose dependence of the value genetic damage on level of radioactive pollution was observed.     

Transgenic plants are sensitive bioindicators of nuclear pollution caused by the Chernobyl accident

To evaluate the genetic consequences of radioactive contamination originating from the nuclear reactor accident of Chernobyl on indigenous populations of plants and animals, it is essential to determine the rates of accumulating genetic changes in chronically irradiated populations. An increase in germline mutation rates in humans living close to the Chernobyl Nuclear Power Plant site, and a two- to tenfold increase in germline mutations in barn swallows breeding in Chernobyl have been reported. Little is known, however, about the effects of chronic irradiation on plant genomes. Ionizing radiation causes double-strand breaks in DNA, which are repaired via illegitimate or homologous recombination. We make use of Arabidopsis thaliana plants carrying a beta-glucuronidase marker gene as a recombination substrate to monitor genetic alterations in plant populations, which are caused by nuclear pollution of the environment around Chernobyl. A significant (p<0.05) increase in somatic intrachromosomal recombination frequencies was observed at nuclear pollution levels from 0.1-900 Ci/km2, consistent with an increase in chromosomal aberrations. This bioindicator may serve as a convenient and ethically acceptable alternative to animal systems.     

Osteogenic sarcoma of the maxillary alveolus occurring five years following the Chernobyl nuclear accident

A novel member of the opioid receptor family (orphan ORL receptor) was cloned in 1994, followed by the discovery of its endogenous ligand OFQ or nociceptin in 1995. ORL receptor has 50% homology with conventional opioid receptor, and OFQ is structurally homologous with dynorphin A. Whether the two systems are functionally antagonistic or synergistic with each other is a subject of future research.     

Tick-borne encephalitis (TBE) epidemiology in the Brest Province of the Republic of Belarus

BACKGROUND: Lens adherence and a reduced postlens tear film circulation have been suggested as factors contributing to some adverse reactions in extended wear of hydrogel contact lenses. In this study, we determined lens fitting and postlens tear film characteristics during closed-eye wear. METHODS: Twenty subjects wore hydrogel lenses for 3 h of eye closure, followed by 30 min of open-eye wear. Lens movement was measured with a video biomicroscope. Postlens tear film appearances in specular reflection were classified as either amorphous, or as one of four color intensity grades, where a colored appearance was taken as indicative of a depleted postlens tear film. RESULTS: All subjects showed lens adherence (movement < 0.1 mm) and postlens tear film depletion within 45 min of eye closure. These changes were sustained for the remainder of the closed-eye period, but were reversed within 15 min of eye opening. Lens adherence was associated with colored postlens tear film patterns of any intensity. CONCLUSION: Closed-eye wear was invariably associated with the onset of lens adherence and postlens tear film depletion. This finding emphasizes the need for adequate lens movement during the open-eye phase of extended wear.     

Thyroid neoplasms in some regions of Russia after radiation accident in Chernobyl

There is an increase of thyroid carcinoma incidence in regions contaminated after the Chernobyl accident as well as in Russia on the whole. The most considerable increase occurred in younger age groups of population. No difference in thyroid tumors structure was found in polluted with radionuclides and non-polluted regions.     

The clinico-hematological indices of the participants in the cleanup of the aftermath of the Chernobyl accident

Clinicohematological investigations and cytogenetic analysis of blood lymphocytes were made 5-7 years after the Chernobyl accident in 201 liquidators who had worked in the radionuclide-contaminated zone. Among the somatic diseases found in the examinees statistically more prevalent were cardiovascular and gastrointestinal affections, asthenic syndrome, thyroid disorders. Hemograms presented a rise in hemoglobin, red cell and eosinophil content, a drop in the number of neutrophils. A tendency to erythrocytosis was observed in 20.3% of the wreckers. Dicenters and rings were abundant in the lymphocytes of 69% of the cytogenetically examined examinees 5-7 years after the exposure to radiation.