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PubMedDate not supplied

Five-year clinical and angiographic follow-up after intracoronary iridium-192 radiation therapy.

BACKGROUND: Ionizing gamma radiation has been shown to reduce neointimal formation and the incidence of restenosis after balloon angioplasty and stenting in clinical trials. However, the long-term effects of this therapy are unknown. The first cohort of patients to receive intracoronary gamma radiation after balloon angioplasty for the prevention of restenosis have completed a 5-year angiographic and clinical follow-up. The outcome of these patients is presented and discussed. METHODS: Twenty-one patients with unstable angina (22 arteries) underwent standard balloon angioplasty. Intracoronary radiation therapy was performed immediately after the intervention using an Iridium-192 source wire hand-delivered to the angioplasty site. All patients were followed clinically and Quantitative Coronary Analysis (QCA) was performed at 6, 24, 36 and 60 months. RESULTS: Target lesion revascularization occurred in six lesions, three of which were total occlusions (two early within 30 days and one occurred at 2 years), and one patient had a myocardial infarction attributable to a nontarget vessel. Serial QCA detected a binary restenosis rate of 28.6% (n=6) at 6 months. The late loss (0.29 mm) and loss index (0.25) remained low at 2, 3 and 5 years. Angiographic complications included four aneurysms (two procedure related and two occurring within 3 months). At 2 years, only one aneurysm increased in size (46 vs. 27 mm(2)); and at 3 and 5 years, all aneurysms remained unchanged. No other angiographic complications were observed. CONCLUSION: The early clinical and angiographic effects of intracoronary gamma radiation were maintained at 5 years without further increase in the aneurysm formation or apparent new adverse effects related to the radiation therapy between 2 and 5 years.

Adult↗
PubMed1999

Pathologic and technical considerations in the treatment of ductal carcinoma in situ of the breast with lumpectomy and radiation therapy.

BACKGROUND: Lumpectomy and radiation therapy is considered a standard treatment option for ductal carcinoma in situ (DCIS) of the breast. The incidence of locally recurrent carcinoma using this therapeutic approach ranges from 6%-19%. Multiple studies have attempted to identify factors associated with the development of local recurrences in these patients. Despite extensive reports examining this issue, no factor(s) has consistently been correlated with outcome. METHODS: This review examines the criteria that various authors have proposed as being associated with recurrence, including DCIS grade, size, histologic subtype, status of surgical margins, and technical factors to help clarify their roles in optimizing treatment outcome. The issue of the definition of the type of recurrence is also addressed. RESULTS: Though multiple studies have examined the impact of grade, histologic subtype, necrosis, and DCIS size on outcome, no consistent results have been observed to suggest that these factors can be routinely used to guide therapy. The adequacy of excision appears to correlate with local control but is imprecisely defined by margin status alone. Based upon recent data, it appears that atypical ductal hyperplasia and cancerization of lobules in the context of coexistent DCIS, may need to be considered as part of the DCIS lesion that should be excised. This issue may account for some of the disparate results of different studies of DCIS. For statistical purposes, recent studies also suggest that only recurrences developing within or adjacent to the bed of the initial DCIS lesion should be considered when analyzing factors associated with outcome. Recurrences developing elsewhere in the breast may include new DCIS and invasive lesions that bear no biologic relationship with the initial DCIS lesion. Finally, since it is impossible to insure that all DCIS has been removed, it may be more appropriate to consider DCIS lesions as adequately or inadequately excised instead of completely or incompletely excised. Since DCIS is essentially a microscopic disease, pathologists should have a primary role in helping to define the adequacy of excision. CONCLUSIONS: Additional studies with complete pathology review and longer follow-up are needed to reach a consensus on which prognostic factors are consistently associated with recurrence for patients with DCIS treated with lumpectomy and radiation therapy. At the present time, adequacy of excision appears to correlate with outcome. However, more precise and consistent methods need to be developed to assist in the determination of adequate DCIS extirpation.

Breast Neoplasms↗
PubMedDate not supplied

[Study on genetic radioresistance of natural Drosophila Melanogaster population from radionuclide contaminated regions of Byelarus].

Over the period from 1998 to 2000 adaptation to unfavorable ecological factors was revealed to be formed in natural Drosophila melanogaster populations from various regions of Belarus with increased radiation background due to the Chernobyl accident. This adaptation was shown to be of non-specific character, since the populations from radiation regions were more resistant to the effect of not only factors of physical nature (irradiation), but also to that of chemical mutagen ethylmethanesulphonate. Assessment of population resistance was carried out by means of tests of dominant lethal mutations and recessive sex-linked lethal mutations.

Animals↗
PubMed1998

Pharmacological management of acute radiation morbidity.

BACKGROUND: The acute radiation morbidity may be a serious problem for the patient and may be decreased by pharmacological approaches. MATERIAL AND METHODS: A database research (Medline, Cancerlit, DIMDI, etc.) was performed in order to obtain pharmacological approaches to decrease the acute radiation morbidity. The evaluation was focused on therapeutic principles but not on special drugs. RESULTS: Different approaches may be chosen to protect healthy tissues from the effects of ionizing radiation: 1. administration of cyto- or radioprotective agents prior to irradiation, 2. administration of agents to avoid additional secondary toxicity by inflammation or superinfection during the treatment cycle (supportive care) and 3. administration of rescue agents, such as bone marrow CSFs or hyperbaric oxygen (HBO), after therapy. For radioprotection, there are reports on cellular protection by vitamine E, vitamine C, beta carotene, ribose-cysteine, glutamine, Mgcl2/adenosine triphosphate and WR-2721 (amifostine). In general, preclinical studies show that the combination of pretreatment with amifostine, irradiation, and G-CSF after radiation enhances hematologic recovery. Assessment of these combined effects, including local supportive therapies, merits further clinical investigation. There are data from prospective studies as well as from empirical clinical experience, that radioprotection and clinical supportive care may reduce the treatment related morbidity by 10 to 30% either. CONCLUSIONS: A further improvement of the therapeutic ratio is to be expected by systemically combined application of radioprotectors, supportive care and rescue agents.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Chernobyl fallout and outcome of pregnancy in Finland.

Possible effects of Chernobyl fallout on outcome of pregnancy in Finland were evaluated in a nationwide follow-up study. The outcomes were the rate of live births and stillbirths, pregnancy loss, and induced abortions by municipality. Exposure was assessed based on nationwide surveys of radiation dose rate from the Chernobyl fallout, from both external and internal exposures. Using these measurements, we estimated the monthly dose rate for each of the 455 Finnish municipalities. On average, the dose rate from Chernobyl fallout reached 50 microSv per month in May 1986--a doubling of the natural background radiation. In the most heavily affected area, 4 times the normal background dose rates were recorded. Given the underlying regional differences in live birth, stillbirth, and abortion rates, we used longitudinal analysis comparing changes over time within municipalities. A temporary decline in the live birth rate had already begun before 1986, with no clear relationship to the level of fallout. A statistically significant increase in spontaneous abortions with dose of radiation was observed. No marked changes in induced abortions or stillbirths were observed. The decrease in the live birth rate is probably not a biological effect of radiation, but more likely related to public concerns of the fallout. The effect on spontaneous abortions should be interpreted with caution, because of potential bias or confounding. Further, there is little support in the epidemiologic literature on effects of very low doses of radiation on pregnancy outcome.

Abortion, Spontaneous↗
PubMed1999

Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures.

OBJECTIVES: The aim of this study was to accurately assess the radiation exposure received by patients during cardiac catheterization in a large sample representative of the current state of practice in cardiac angiography. BACKGROUND: Radiation exposure to patients and laboratory staff has been recognized as a necessary hazard in coronary angiography. The effects on x-ray exposure of the increased complexity of coronary angiographic procedures and, in particular, the increasing use of coronary artery stenting, have not been adequately addressed in previous studies. METHODS: X-ray exposure measurements were performed on a consecutive series of 972 patients undergoing 992 diagnostic and interventional studies in the Mayo Clinic catheterization laboratory within an eight week period in late 1997. Data were acquired from 706 diagnostic procedures and 286 interventional procedures using a real-time exposure measurement system to continuously calculate and record the exposure rate and total exposure, reflecting all parameters relevant to the specific patient and procedure situation. RESULTS: The median exposure for all 992 procedures was 41.8 mC/kg (162.1 R); the corresponding values for diagnostic and interventional procedures were 34.9 and 95.6 mC/kg, respectively (135.3 vs. 370.5 R). There were significant differences in the fluoroscopy exposure time between diagnostic and interventional procedures: 4.7 min vs. 21.0 min. Heavier patients (>83 kg) received x-ray exposures at a significantly higher rate than did lighter patients (<83 kg) during both fluoroscopy and cine; 44.9 mC/kg/min (173.9 R/min) vs. 27.9 mC/kg/min (108.3 R/min) for cine exposure rate and 2.3 mC/kg/min (8.8 R/min) vs. 1.5 mC/kg/min (5.8 R/min) for fluoroscopy exposure rate. CONCLUSIONS: Changes in practice have led to higher values for patient x-ray radiation exposures during cardiac catheterization procedures. The real-time display and recording of x-ray exposure facilitates the reduction of exposure in the catheterization laboratory.

Aged↗
PubMed1990

Radiation hormesis: an evolutionary expectation and the evidence.

Fundamental to evolutionary biology is the tendency for organisms to become progressively adapted to those environments to which they are most frequently exposed. Since background radiation is a universal component of our environment, radiation hormesis is an evolutionary expectation. Whole-of-life experiments and more numerous (and evolutionarily more artificial) shorter duration and higher dose-rate experiments are consistent with this expectation. Additional research is needed especially at the molecular level to search for underlying mechanisms, and implications for radiation protection guidelines need to be analyzed.

Adaptation, Physiological↗
PubMed1987

Radionuclide monitoring in Northern Ireland of the Chernobyl nuclear reactor accident.

Northern Ireland received higher radiation doses due to the radionuclide contamination from the Chernobyl nuclear reactor accident than did the south of England. Levels of radioactive iodine ((131)I) and caesium ((137)Cs) in cows' milk in Northern Ireland increased to 166 and 120 Bq/l respectively in May 1986, but had decreased by factors of one million, and of twenty-five, respectively, by 1 September 1986. The resultant radiation doses represent less than one per cent of those received by a Northern Ireland individual over a period of 40 years from natural background radiation sources. The added risk to any individual from the Chernobyl accident will therefore be very small and may best be judged in the context of the enormously greater risk of death due to potentially preventable diseases, such as smoking-related lung cancer, and coronary heart disease.

Adult↗
PubMed1995

Biomarkers for low-level exposure causing epigenetic responses in stem cells.

Our current understanding of experimental in vitro and in vivo studies, as well as of epidemiological data, suggests that carcinogenesis is the result of many endogenous and exogenous factors interacting during a multi-step, multi-mechanism process. No single factor "causes" cancer. Carcinogenesis is known to involve both mutagenic and nonmutagenic processes. Therefore, the objective of this review is to examine how low dose exposure to ionizing radiation might contribute to the carcinogenic process and if measurable "biomarkers" might be used to monitor the susceptibility, exposure, biological consequence and clinical disease patterns attributable to ionizing radiation. While the primary biomarker for ionizing radiation has been DNA damage and genetic/chromosomal mutations, possible effects on apoptosis and epigenetic processes have been examined. The search for biomarkers of cytotoxic (apoptotic) and epigenetic events induced by low-level ionizing radiation was thought to be difficult in view of the fact that controlled apoptotic and epigenetic events occur constantly in a healthy body exposed to background radiation. In addition, if the stem cell is the target cell for low-level radiation exposure, detection of biomarkers in this small subpopulation of cells in any tissue places severe limitations on any practical noninvasive means to identify such biomarkers. Last, a critical re-examination of the cancer incidence data of the Hiroshima/Nagasaki A-bomb survivors is suggested in view of modifying factors such as caloric restriction and post-irradiation trauma/treatment that could affect the multi-stage nature of carcinogenesis.

Animals↗
PubMedDate not supplied

[Effect of low-dose gamma-irradiation of silkworm eggs on the development of the mulberry silkworm (Bombyx mori L.)].

Chronic gamma-irradiation of an egg at a dose-rate 100, 1000 and 4000 times as high as that of the natural radiation background significantly accelerates the development of Bombyx mori L. The caterpillar development may also be stimulated by a single exposure of the egg to 2 Gy radiation. The acceleration of the caterpillar growth promotes the increase in the cocoon weight and the raw-silk mass.

Animals↗
PubMed1998

Issues in the reconstruction of environmental doses on the basis of thermoluminescence measurements in the Techa riverside.

The potential of thermoluminescence measurements of bricks from the contaminated area of the Techa river valley, Southern Urals, Russia, for reconstructing external exposures of affected population groups has been studied. Thermoluminescence dating of background samples was used to evaluate the age of old buildings available on the river banks. The anthropogenic gamma dose accrued in exposed samples is determined by subtracting the natural radiation background dose for the corresponding age from the accumulated dose measured by thermoluminescence. For a site in the upper Techa river region, where the levels of external exposures were extremely high, the depth-dose distribution in bricks and the dependence of accidental dose on the height of the sampling position were determined. For the same site, Monte Carlo simulations of radiation transport were performed for different source configurations corresponding to the situation before and after the construction of a reservoir on the river and evacuation of the population in 1956. A comparison of the results provides an understanding of the features of the measured depth-dose distributions and height dependencies in terms of the source configurations and shows that bricks from the higher sampling positions are likely to have accrued a larger fraction of anthropogenic dose from the time before the construction of the reservoir. The applicability of the thermoluminescent dosimetry method to environmental dose reconstruction in the middle Techa region, where the external exposure was relatively low, was also investigated.

Alpha Particles↗
PubMed2003

Tritium release from nuclear power plants in Taiwan.

Tritium is produced in light water reactors from various sources and the design source terms for both BWR and PWR plants are reviewed. The chemical forms of tritium produced in the coolant are discussed in terms of water radiolysis and free radical reactions in the reactor core regions, and the major form of tritium released from the coolant systems is confirmed to be tritiated water. The tritium activity concentrations and inventories in various coolant systems have been measured, and the release pathways of tritium from nuclear power plants are also reviewed in this paper. Decreasing trends of tritium release from nuclear power plants in both liquid waste and ventilation sources have been observed in Taiwan. The impact of tritium release on environmental radiation is estimated with well-established screening models, and the results confirm that the impact is less than 1% of the regulatory limits and less than 0.1% of the natural radiation background.

Air Pollutants, Radioactive↗
PubMed2001

Neutron environments on the Martian surface.

Radiation is a primary concern in the planning of a manned mission to Mars. Recent studies using NASA Langley Research Center's HZETRN space radiation transport code show that the low energy neutron fluence on the Martian surface is larger than previously expected. The upper atmosphere of Mars is exposed to a background radiation field made up of a large number of protons during a solar particle event and mixture of light and heavy ions caused by galactic cosmic rays at other times. In either case, these charged ions interact with the carbon and oxygen atoms of the Martian atmosphere through ionization and nuclear collisions producing secondary ions and neutrons which then interact with the atmospheric atoms in a similar manner. In the past, only these downward moving particles have been counted in evaluating the neutron energy spectrum on the surface. Recent enhancements in the HZETRN code allow for the additional evaluation of those neutrons created within the Martian regolith through the same types of nuclear reactions, which rise to the surface. New calculations using this improved HZETRN code show that these upward moving neutrons contribute significantly to the overall neutron spectrum for energies less than 10 MeV.

Computer Simulation↗
PubMed1987

Radioactive iodine and cesium in travellers to different parts of Europe after the Chernobyl accident.

Thyroid uptake of 131I was measured in 130 volunteers following the nuclear power plant accident at Chernobyl in April 1986. Ninety of these volunteers had been travelling in different parts of eastern Europe at the time of or immediately after the accident while 40 persons were permanently in Sweden. Also, 28 additional healthy volunteers, living in Sweden, were chosen for a long-term follow-up of the time-course of 134Cs and 137Cs whole body uptake. The highest levels of 131I were found in persons having visited Poland (mean value 3.27 kBq +/- 3.68 SD, extrapolated to April 27) while persons that had stayed in other parts of eastern or northern Europe showed significantly lower levels (p less than 0.01). The whole body burdens of cesium radionuclides were barely detectable immediately after the accident but increased gradually throughout the observed period. After five months nine farmers from a high fallout area in central Sweden had reached mean values of 4.20 kBq (+/- 3.34 SD) of 134Cs and 137Cs while six nonfarmers from the Stockholm area showed significantly lower levels, 0.64 kBq (+/- 0.24 SD, p less than 0.05). The radiation doses from the observed amounts of iodine and cesium isotopes reported in this study reflect only a marginal addition to the already existing dose from the natural environmental background radiation.

Accidents↗
PubMed1975

X-ray emmissions from colour television receivers in New Zealand.

Colour television receivers produced for the New Zealand market have been tested to ensure that any x-radiation emmissions result in dose rates less than the 0.5mrem/h (500murem/h) limit allowed under the Radiation Protection Regulations, 1973. Five receivers representing the five different models available on the New Zealand market were surveyed and the maximum dose rate measured from any screen was 0.05murem/h. The estimated maximum annual radiation dose to an average viewer from the receivers surveyed will be less than 5murem or less than 5 x 10-minus 3 percent of the dose from natural background radiation. This level of x-radiation is well below that which could constitute a health hazard.

Child↗
PubMed1999

Radionuclides in the lichen-caribou-human food chain near uranium mining operations in northern Saskatchewan, Canada.

The richest uranium ore bodies ever discovered (Cigar Lake and McArthur River) are presently under development in northeastern Saskatchewan. This subarctic region is also home to several operating uranium mines and aboriginal communities, partly dependent upon caribou for subsistence. Because of concerns over mining impacts and the efficient transfer of airborne radionuclides through the lichen-caribou-human food chain, radionuclides were analyzed in tissues from 18 barren-ground caribou (Rangifer tarandus groenlandicus). Radionuclides included uranium (U), radium (226Ra), lead (210Pb), and polonium (210Po) from the uranium decay series; the fission product (137Cs) from fallout; and naturally occurring potassium (40K). Natural background radiation doses average 2-4 mSv/year from cosmic rays, external gamma rays, radon inhalation, and ingestion of food items. The ingestion of 210Po and 137Cs when caribou are consumed adds to these background doses. The dose increment was 0.85 mSv/year for adults who consumed 100 g of caribou meat per day and up to 1.7 mSv/year if one liver and 10 kidneys per year were also consumed. We discuss the cancer risk from these doses. Concentration ratios (CRs), relating caribou tissues to lichens or rumen (stomach) contents, were calculated to estimate food chain transfer. The CRs for caribou muscle ranged from 1 to 16% for U, 6 to 25% for 226Ra, 1 to 2% for 210Pb, 6 to 26% for 210Po, 260 to 370% for 137Cs, and 76 to 130% for 40K, with 137Cs biomagnifying by a factor of 3-4. These CRs are useful in predicting caribou meat concentrations from the lichens, measured in monitoring programs, for the future evaluation of uranium mining impacts on this critical food chain.

Animals↗
PubMedDate not supplied

[The possible role of the elements of protein secondary structure in adaptation to the action of ionizing radiation].

Changes in the secondary structure of enzymes induced by gamma-rays 60Co at doses not exceeding one ionization per macromolecule were studied to elucidate a possible role of radiation-chemical processes in the evolution of proteins. The data on the comparative radioresistance of various types of secondary protein structures, alpha-helix, parallel and anti-parallel beta-structures, and beta-turn, were obtained by the method of circular dichroism. It was shown that beta-turns were resistant against radiation, alpha-helix was relatively stable, and beta-layer underwent significant changes. The importance of these structural types in the evolution of proteins is discussed. A special role of beta-turn as structural elements fixing the confirmation of macromolecules and therefore responsible for adaptation of the protein structure against a constant radiation background is proposed.

Adaptation, Physiological↗
PubMed2005

Distribution of naturally occurring radionuclides in soils of the southern districts of Bangladesh.

The activity concentrations of naturally occurring radioactive materials in soil samples of an elevated radiation background area of nine southern districts of Bangladesh were determined using gamma-ray spectrometry with an aim of evaluating the environmental radioactivity. The outdoor and indoor external effective dose rates and the radiation hazard indices from the soil activity were evaluated with an aim of minimising the harmful effects of ionising radiation to the population of the area concerned. The activity of (137)Cs was measured and observed in some of the locations.

Bangladesh↗