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At least 1,729 records · Page 96Linked to original sources
PubMed1978

[The "ideal" pacemaker (author's transl)].

The therapeutic role of chronic cardiac pacing in cardiology has significantly altered for two fundamental reasons: a) on the one hand, there has been a widespread increase in the indications for cardiac stimulation, and consequently, today, approximately 50% of the patients with pacing do not suffer from advanced atrioventricular (A-V) block or syncopal attacks, but are frequently suffering from other pathological conditions: episodes of paroxysmal arrhythmia, atrial disease, depression of the habitual pacemaker by drugs or in the course of cardiomyopathy; b) on the other hand, through technological progress the life of the generator has been lengthened (lithium, plutonium), more variable frequencies within relatively high limits are available, electrodes, wiring, circuits etc. have improved. This extended use of the pacemaker, however, creates in itself a series of problems: it is now possible to envisage the characteristics of the "ideal" pacemaker, in other words, a stimulation unit endowed with resistance, modulation, self-control, innocuosness.

Cardiac Pacing, Artificial↗
PubMed1994

[Management of accidental internal exposure].

Radionucleides can penetrate into the body via the lung, the digestive tract, wounds and sometimes through healthy skin. Once they have penetrated the body, they can either remain localized at the site of entry or be rapidly metabolized. The risk is late effects. Radioelements must be eliminated as rapidly as possible decreasing the exposure proportionally. The effectiveness of the treatment depends on early institution. Nevertheless, emergency intensive care or surgery may be required. As soon as possible, explorations must be carried out to evaluate the level of contamination (human spectrometry, radiotoxicological examinations) and to start treatment. Modalities include non-specific techniques (lavage, insolubilization, laxatives) and specific techniques such as complexation or isotopic dilution (iodine for iodine, Prussian blue for cesium, DTPA for plutonium, Diamox or sodium bicarbonate for uranium). Surgical cleaning of wounds and burns is an excellent means of decontamination. External contamination is often associated. Further contamination must be prevented immediately.

Humans↗
PubMed1995

Gamma irradiation of the fetus damages the developing hemopoietic microenvironment rather than the hemopoietic progenitor cells.

Hemopoiesis is the product of two components: the hemopoietic tissue and the regulatory stromal microenvironment in which it resides. Plutonium-239, incorporated during fetal development, is known to cause deficient hemopoiesis. A predetermined equivalent gamma-ray dose has now been used in combination with cross-transplantation experiments to separate these two components and define where the damage arises. It was confirmed that 1.8 Gy gamma irradiation at midterm gestation caused a 40% reduction in the hemopoietic stem (spleen colony-forming) cell population of their offspring which persisted to at least 24 weeks of age. Spleen colony formation after sublethal doses of gamma rays reflected this reduced complement of endogenous stem cells. The regulatory hemopoietic microenvironment, measured as fibroblastoid colony-forming cells, was similarly depleted. Normal growth of the CFU-S population after transplantation into standard recipients showed that the quality of the stem cell population in the offspring of irradiated mothers was not affected. By contrast, when used as recipients of a bone marrow transplant from either normal or irradiated offspring, the offspring of irradiated mothers were unable to support normal growth: there was a twofold difference in the number of CFU-S per femur for at least 100 days after transplantation. There were 70% fewer CFU-F in the femur 1 month after bone marrow transplantation when the offspring of irradiated mothers were used as transplant recipients compared to when normal offspring were used. This not only confirmed their reduced capacity to host normal stem cells but also indicated that CFU-F in the transplant were unable to compensate for the poor microenvironment in the irradiated offspring hosts. It is concluded that irradiation at midterm gestation damages the developing regulatory microenvironment but not the hemopoietic stem cell population that it hosts.

Animals↗
PubMed1993

[Prevalence of radioactive particles in the territory of Byelorussia and their contents in the lungs].

Examination conducted in 1987--1988 included 200 samples of the autopsy material of subjects who died of various causes in different regions of Byelorussia. It revealed the presence of "hot" particles (i.e. particles with high specific radioactivity) in 50% of the samples taken from the northwest and in 70% of those from the southeast regions. A correlation was found to exist between the radioactive particles content in the soil, air and lungs of residents from the contaminated territory. It was shown that in 1990--1991, in contrast to 1987--1988, the particles content in a single lung sample reduced, which was associated both with mechanical removal of particles and their disintegration and, as a consequence with the accumulation of plutonium in the body. Study of radioactive particles distribution in the whole lung showed that at present they are found primarily in the lower segments.

Autopsy↗
PubMed1994

Primary liver tumors among Danish patients exposed to Thorotrast.

The potential carcinogenic effects of internally deposited alpha-particle-emitting nuclides, notably plutonium, in the liver in humans are unknown but are of concern in relation to exposures from the nuclear industry. However, patients injected with the radiographic contrast medium Thorotrast are chronically exposed to alpha-particle radiation from 232ThO2 in the liver. Among 1003 patients injected with Thorotrast, 584 of whom were alive 15 years after the injection and 40 at the end of follow-up, a total of 127 liver cancers were diagnosed, 45 of which were hepatocellular carcinomas, 41 cholangiocarcinomas and 33 hemangiosarcomas. The median time from injection to diagnosis was 35 years (range 18-48) and the cumulative frequency was 55.4% after 48 years. In univariate and multivariate analyses, the cumulative frequency of liver cancer was best described as a function of the estimated mean cumulative alpha-particle radiation dose to the liver 15 years ago, being independent of age, gender and volume of injected Thorotrast. This may be interpreted to mean that the liver cancer rate is not related to the dose rate and that the period from malignant transformation to diagnosis of cancer is 15 years. The risk of liver carcinogenesis induced by alpha-particle radiation, assuming 15 years from induction to diagnosis, was estimated to be 712 cases/10(4) persons per gray. This value is considerably higher than estimated earlier.

Adolescent↗
PubMed1993

[Radionuclide inhalation during agricultural work in the regions polluted by the Chernobyl accident].

With pollution of agricultural fields by plutonium at a level of more than 3.7 kBg/m2 and cesium more than 7.4 MBq/m2 radionuclide levels in tractor cabin can exceed the permissible level. However field work being seasonal, annual level of inhaled radionuclides does not exceed the permissible limit. Actually the equivalent dose for the lungs does not exceed just few mSv under conditions of agricultural production.

Accidents, Occupational↗
PubMedDate not supplied

[The radioecological problems of Eurasia and the sources of radioactive environmental contamination in the former USSR].

There is three major sites of radioactive environmental contamination in the former USSR: the Chelyabinsk region in the Urals, Chernobyl NPP in Ukraine and Novaya Zemlya in the Arctic Ocean. The first mentioned is the most important with regard to local (potential) contamination, the last one dominates the global contamination. A number of sites and sources are less well known with regard to environmental contamination. This is thus the case for the plutonium production factories at Tomsk and Dodonovo. More information on nuclear reactors in lost or dumped submarines is also needed. From a global point of view reliable assessment of the radioactive run-off from land and deposits of nuclear waste in the Arctic Ocean are in particular pertinent.

Accidents↗
PubMedDate not supplied

[Uric acid in blood serum and incidence of hyperuricemia in irradiated people. Connection with radioactive and nonradioactive factors].

A total of 1,002 workers aged 36 to 72 years who were engaged in atomic industry and exposed to external gamma-irradiation and incorporated plutonium 239 in a wide dosage range. The levels of uric acid (UA), the incidence of hyperuricemia and their association with 2 radiation and 12 nonradiation factors were studied in the examinees. There was a positive correlation between the purine metabolic parameters and the total dosage of external gamma-irradiation, sex (UC levels were higher in males than in females), body weight index, essential hypertension, and the type of haptoglobin 1-1. The influence of nonradiation factors on the parameters in question were substantially greater than that of external irradiation. Linear regression equations were derived for the dependence of the levels of UA and hyperuricemia upon the influencing factors.

Adolescent↗
PubMed1996

Methylation of the estrogen receptor CpG island in lung tumors is related to the specific type of carcinogen exposure.

Promoter methylation has recently been shown to be an alternative to mutation in inactivating tumor suppressor genes in human neoplasia. Although specific carcinogen exposures have been associated with characteristic mutation patterns in genes, the factors that lead to promoter hypermethylation remain unknown. One gene target for inactivation through promoter methylation is the estrogen receptor (ER). The purpose of this investigation was to determine the methylation status of this gene in lung tumors from smokers and those who never smoked and in rodents exposed to specific environmental carcinogens. Promoter methylation at the ER locus was detected in 4 of 11 tumors from never-smokers (36.4%) and 7 of 35 tumors from smokers (20%, P < 0.001). Lung tumors induced by the tobacco-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone also had a low incidence (16.7%) of ER methylation. In marked contrast, spontaneous and plutonium-induced tumors had a very high (81.8%) incidence of ER methylation. X-ray-induced tumors had an intermediate frequency of ER methylation (38.1%). The presence of ER methylation was associated with absent ER expression in rodent lung cancer cell lines. These results show for the first time that gene-specific promoter methylation can be modulated differentially depending on carcinogen exposure.

Animals↗
PubMed1996

Cancer mortality in the exposed population of the Techa River area.

Radioactive contamination and population exposure resulted from the operation of the Mayak complex, a plutonium-production facility in the Southern Urals. The highest doses were received by residents along the Techa River into which wastes from the complex leaked between 1949 and 1956. A registry was established containing data on 29,528 persons and information on deaths (9426 by 1982; 6439 death certificates) and cancer cases. Six groups differing in exposure levels were set up for the cohort analysis. The range of doses to red bone marrow in these cohorts was from 1.64 to 0.176 Sv. Leukaemia and solid cancer mortality over the 33-year period of exposure was analysed. The age-standardized total cancer mortality rates and their 95% confidence intervals account for 140 (131-150) and 105 (101-109) per 100,000 person-years for the entire exposed and entire control population. The analysis of cancer mortality in different organs has shown increased rates for leukaemia in one exposed group and for cancers of the uterine corpus and cervix in the other exposed group, as compared to the identical control groups.

Humans↗
PubMed1996

First attempts at validation of radiation exposure of the population along the Techa River, southern Urals.

A research programme sponsored by the German Federal Ministry for the Environment, Nature Protection and Nuclear Safety (BMU) was conducted during 1992 and 1993 in the Southern Urals, to provide an initial validation and comparison of results of population exposure arising from the release of radioactive waste from the MAYAK nuclear facility between the years 1948 and 1967. This programme included investigations of the contamination of the soil, of food (milk, drinking-water, potatoes) and whole-body-counter measurements of inhabitants of settlements at the Techa River. The nuclides of interest were plutonium isotopes and the long-lived fission products 137Cs and 90Sr. Results of these investigations, particularly in and around the village of Muslyumovo (78 km downstream from the point of release of the radioactive waste into the Techa River), are shown. These investigations are a first step towards an independent validation of the enormous data base collected by the Russian institutes and of derived values of the doses to the population of the Techa River.

Environmental Exposure↗
PubMedDate not supplied

Safe handling of tissue containing radioactive substances.

Patients recently treated with radioactive isotopes may present problems or even hazards during physical examination, operation or autopsy, especially following the use of iodine isotopes and 198Au. 32P is rarely a significant hazard. Contamination of victims of radiation accidents may be a problem initially, but they are usually promptly decontaminated. Guidance of the hospital's radiation safety officer is helpful, particularly with regard to handling of contaminated persons or materials. Long-lived isotopes, such as radium or thorotrast, are usually present in too low concentration to be dangerous. Projected use of artificial hearts powered by plutonium should not be hazardous because of adequate shielding of the source.

Autopsy↗
PubMedDate not supplied

[Genotype analysis of biochemical status in people irradiated with significant doses of radiation].

416 workers of the enterprise of a nuclear industry aged from 52 to 78 years exposed to chronic influence of external gamma-irradiation in summary dozes 1.0-7.56 Gy and plutonium-239 incorporation, (in 32.3% of cases exceeding the allowable limit) were studied. A correlation between a complex of 26 biochemical and immunochemical parameters and the radiating factors was investigated at different haptoglobin genotypes (Hp). It was established, that the greatest number of changes of biochemical parameters related to radiating influence, was observed at the people with a genotype Hp 2-2 (7 parameters), to a lesser degree--at a genotype Hp 2-1 (5 parameters) and in some more smaller degree--at a genotype Hp 1-1 (4 parameters). All investigated people with a genotype 2-2 were characterised by increase of serum protein entropy.

Aged↗