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At least 451 records · Page 25Linked to original sources
PubMed2003

In vivo and in vitro measurements of complex-type chromosomal exchanges induced by heavy ions.

Heavy ions are more efficient in producing complex-type chromosome exchanges than sparsely ionizing radiation, and this can potentially be used as a biomarker of radiation quality. We measured the induction of complex-type chromosomal aberrations in human peripheral blood lymphocytes exposed in vitro to accelerated H-, He-, C-, Ar-, Fe- and Au-ions in the LET range of approximately 0.4-1400 keV/micrometers. Chromosomes were analyzed either at the first post-irradiation mitosis, or in interphase, following premature condensation by phosphatase inhibitors. Selected chromosomes were then visualized after FISH-painting. The dose-response curve for the induction of complex-type exchanges by heavy ions was linear in the dose-range 0.2-1.5 Gy, while gamma-rays did not produce a significant increase in the yield of complex rearrangements in this dose range. The yield of complex aberrations after 1 Gy of heavy ions increased up to an LET around 100 keV/micrometers, and then declined at higher LET values. When mitotic cells were analyzed, the frequency of complex rearrangements after 1 Gy was about 10 times higher for Ar- or Fe- ions (the most effective ions, with LET around 100 keV/micrometers) than for 250 MeV protons, and values were about 35 times higher in prematurely condensed chromosomes. These results suggest that complex rearrangements may be detected in astronauts' blood lymphocytes after long-term space flight, because crews are exposed to HZE particles from galactic cosmic radiation. However, in a cytogenetic study of ten astronauts after long-term missions on the Mir or International Space Station, we found a very low frequency of complex rearrangements, and a significant post-flight increase was detected in only one out of the ten crewmembers. It appears that the use of complex-type exchanges as biomarker of radiation quality in vivo after low-dose chronic exposure in mixed radiation fields is hampered by statistical uncertainties.

Biomarkers↗
PubMed2003

Mortality from cancer and other causes among male airline cockpit crew in Europe.

Airline pilots and flight engineers are exposed to ionizing radiation of cosmic origin and other occupational and life-style factors that may influence their health status and mortality. In a cohort study in 9 European countries we studied the mortality of this occupational group. Cockpit crew cohorts were identified and followed-up in Denmark, Finland, Germany, Great Britain, Greece, Iceland, Italy, Norway and Sweden, including a total of 28,000 persons. Observed and expected deaths for the period 1960-97 were compared based on national mortality rates. The influence of period and duration of employment was analyzed in stratified and Poisson regression analyses. The study comprised 547,564 person-years at risk, and 2,244 deaths were recorded in male cockpit crew (standardized mortality ratio [SMR] = 0.64, 95% confidence interval [CI] = 0.61-0.67). Overall cancer mortality was decreased (SMR = 0.68; 95% CI = 0.63-0.74). We found an increased mortality from malignant melanoma (SMR = 1.78, 95% CI = 1.15-2.67) and a reduced mortality from lung cancer (SMR = 0.53, 95% CI = 0.44-0.62). No consistent association between employment period or duration and cancer mortality was observed. A low cardiovascular mortality and an increased mortality caused by aviation accidents were noted. Our study shows that cockpit crew have a low overall mortality. The results are consistent with previous reports of an increased risk of malignant melanoma in airline pilots. Occupational risk factors apart from aircraft accidents seem to be of limited influence with regard to the mortality of cockpit crew in Europe.

Accidents, Aviation↗
PubMed2005

Checkpoint and physiological apoptosis in germ cells proceeds normally in spaceflown Caenorhabditis elegans.

It is important for human life in space to study the effects of environmental factors during spaceflight on a number of physiological phenomena. Apoptosis plays important roles in development and tissue homeostasis in metazoans. In this study, we have analyzed apoptotic activity in germ cells of the nematode C. elegans, following spaceflight. Comparison of the number of cell corpses in wild type or ced-1 mutants, grown under either ground or spaceflight conditions, showed that both pachytene-checkpoint apoptosis and physiological apoptosis in germ cells occurred normally under spaceflight conditions. In addition, the expression levels of the checkpoint and apoptosis related genes are comparable between spaceflight and ground conditions. This is the first report documenting the occurrence of checkpoint apoptosis in the space environment and suggests that metazoans, including humans, would be able to eliminate cells that have failed to repair DNA lesions introduced by cosmic radiation during spaceflight.

Animals↗
PubMed1988

The response of structure and function of the gravireceptor in a vertebrate to near weightlessness.

The paper sums up results of a 7-day space flight experiment (D-l-Mission-BW-STA 00-STATEX) using growing frog embryos and larvae (Xenopus laevis) as a model system. Evaluation of photographs taken from the surface of sectioned deep-frozen objects, and micrographs using TEM and SEM show no aberrations in the shape, size, position, or respective electron density of the otolith membranes in larvae developed for 154 h under near-zero g. The further evaluation of the "weightless larvae" revealed a probably not yet described otolith-like formation below the dorsal wall of the vestibulum. In the weightless larvae this formation outnumbers, also qualitatively, strongly the 1-g control samples. The swimming behavior of the tadpoles which was observed about one hour after landing of the Space Shuttle showed a typical anomaly (loop swimming), which is known from larvae developed on the clinostat or from fish flown aboard Apollo capsules. An extra result is the lack of striking effects of cosmic radiation on the embryonic development of the flown Xenopus eggs.

Animals↗
PubMed1992

Ionizing radiation exposure of LDEF (pre-recovery estimates).

The long duration exposure facility (LDEF), launched into a 258 nautical mile orbit with an inclination of 28.5 degrees, remained in space for nearly 6 yr. The 21,500 lb NASA satellite was one of the largest payloads ever deployed by the Space Shuttle. LDEF completed 32,422 orbits and carried 57 major experiments representing more than 200 investigators from 33 private companies, 21 universities and nine countries. The experiments covered a wide range of disciplines including basic science, electronics, optics, materials, structures and power and propulsion. A number of the experiments were specifically designed to measure the radiation environment. These experiments are of specific interest, since the LDEF orbit is essentially the same as that of the Space Station Freedom. Consequently, the radiation measurements on LDEF will play a significant role in the design of radiation shielding of the space station. The contributions of the various authors presented here attempt to predict the major aspects of the radiation exposure received by the various LDEF experiments and therefore should be helpful to investigators who are in the process of analyzing experiments which may have been affected by exposure to ionizing radiation. The paper discusses the various types and sources of ionizing radiation including cosmic rays, trapped particles (both protons and electrons) and secondary particles (including neutrons, spallation products and high-LET recoils), as well as doses and LET spectra as a function of shielding. Projections of the induced radioactivity of LDEF are also discussed.

Computer Simulation↗
PubMed2004

Chromosomal aberrations induced by high-energy iron ions with shielding.

Biophysical models are commonly used to evaluate the effectiveness of shielding in reducing the biological damage caused by cosmic radiation in space flights. To improve and validate these codes biophysical experiments are needed. We have measured the induction of chromosomal aberrations in human peripheral blood lymphocytes exposed in vitro to 500 MeV/n iron ion beams (dose range 0.1-1 Gy) after traversing shields of different material (lucite, aluminium, or lead) and thickness (0-11.3 g/cm2). For comparison, cells were exposed to 200 MeV/n iron ions and to X-rays. Chromosomes were prematurely condensed by a phosphatase inhibitor (calyculin A) to avoid cell-cycle selection produced by the exposure to high-LET heavy-ion beams. Aberrations were scored in chromosomes 1, 2, and 4 following fluorescence in situ hybridization. The fraction of aberrant lymphocytes has been evaluated as a function of the dose at the sample position, and of the fluence of primary 56Fe ions hitting the shield. The influence of shield thickness on the action cross-section for the induction of exchange-type aberrations has been analyzed, and the dose average-LET measured as a function of the shield thickness. These preliminary results prove that the effectiveness of heavy ions is modified by shielding, and the biological damage is dependent upon shield thickness and material.

Aluminum↗
PubMed2005

Response of a Si-diode-based device to fast neutrons.

Semiconductor devices based on a Si-detector are frequently used for charged particle's detection; one application being in the investigation of cosmic radiation fields. From the spectra of energy deposition events in such devices, the total energy deposited by the radiation in silicon can be derived. This contribution presents the results of studies concerning the response of this type of detector to fast neutrons. First, the spectrum of energy deposition was established in fast neutron radiation fields with average energies from 0.5 to 50 MeV. It was found that these spectra vary significantly with the neutron energy. The comparison with the spectra registered in photon beams permitted an estimation of the part of energy deposited that could be attributed to neutrons. It was found that this part increases rapidly with neutron energy. The possibilities to use this type of detector for neutron detection and dosimetry for radiation protection are analysed and discussed.

Aircraft↗
PubMed1997

Increase of chromosomal aberrations induced by ionising radiation in peripheral blood lymphocytes of civil aviation pilots and crew members.

This study inquires if there is an increase of chromosomal aberrations by ionising radiation of cosmic origin in civil pilots and flight-crew members. Totals of 37,208 exposed cells and 10,950 control cells, from 192 and 55 donors respectively, were scored averaging 200 observations per subject. The analysis showed the increase of dicentric and ring chromosomes in peripheral blood lymphocytes of the flight personnel. The difference of the total aberration frequencies between exposed and control was statistically significant.

Adult↗
PubMedDate not supplied

Cytogenetics of myelodysplasia and acute myeloid leukaemia in aircrew and people treated with radiotherapy.

Increased risk of acute myeloid leukaemia has been reported in aircrew, possibly in association with cosmic radiation. We studied the cytogenetics of seven aircrew members who had acute myeloid leukaemia or myelodysplasia and found deletion or loss of chromosome 7 in four. The same abnormality was found in eight of 19 patients with leukaemia after radiotherapy alone. By comparison, only 81 of 761 unselected cases of myelodysplasia or acute myeloid leukaemia had the same cytogenetic abnormalities. Our results support the concept that deletions or loss of the long arm of chromosome 7 in myelodysplasia and acute myeloid leukaemia could indicate previous exposure to ionising radiation.

Adult↗
PubMed1998

Accumulation of stress protein 72 (HSP72) in muscle and spleen of goldfish taken into space.

Using Western blot analysis, here, we report the levels of HSP72 in several organs from goldfish which were taken into space on the NASA space shuttle. A remarkable accumulation of HSP72 was detected in muscle and spleen of those fish taken into space as compared with controls. These results suggested that the HSP72 induction is a kind of stress response at the molecular level introduced by the space environment consisting of microgravity and/or cosmic radiation as stressors.

Adaptation, Physiological↗
PubMed2000

In vitro neurotoxic effects of 1 GeV/n iron particles assessed in retinal explants.

The heavy ion component of the cosmic radiation remains problematic to the assessment of risk in manned space flight. The biological effectiveness of HZE particles has yet to be established, particularly with regard to nervous tissue. Using heavy ions accelerated at the AGS of Brookhaven National Laboratory, we study the neurotoxic effects of iron particles. We exposed retinal explants, taken from chick embryos, to determine the dose response relationships for neurite outgrowth. Morphometric techniques were used to evaluate the in vitro effects of 1 GeV/a iron particles (LET 148 keV/micrometer). Iron particles produced a dose-dependent reduction of neurite outgrowth with a maximal effect achieved with a dose of 100 cGy. Doses as low as 10-50 cGy were able to induce reductions of the neurite outgrowth as compared to the control group. Neurite generation is a more sensitive parameter than neurite elongation, suggesting different mechanism of radiation damage in our model. These results showed that low doses/fluences of iron particles could impair the retinal ganglion cells' capacity to generate neurites indicating the highly neurotoxic capability of this heavy charged particle.

Animals↗
PubMed2003

Health hazards and electromagnetic fields.

Biological rhythms, physical wellbeing and mental states are dependent on our electrical brainwave system interacting with the extremely weak electromagnetic fields generated by the Earth's telluric and Cosmic radiations. In a single generation, since the evolution of humankind over millions of years, we are exposed to a wide range of powerful, artificially generated electromagnetic radiation which adversely affects the subtle balance in nature's energy fields and has become the source of so-called 'diseases of civilization'. This also includes electromagnetic sensitivity. Generally, there is a lack of awareness and understanding of the impact electromagnetic fields can have upon health and wellbeing.Our ancestors were acutely aware that certain locations, were perceived to have a positive energy field which was beneficial to health and vitality. Over time, these areas are now referred to as sacred sites for spiritual ceremony and as healing centres. In contrast, there are other geographical locations that can have a negative effect upon health and these are known as geopathic stress zones. It is believed that such zones can interfere with the brain's normal function that inhibits the release of melatonin and other endocrine secretions needed to replenish the immune system. Geopathic stress can affect animals and plant life as well as human beings and significantly contributes to sick building syndrome (SBS). Whilst there is an increasing body of opinion amongst eminent researchers and scientists who are addressing these issues, the establishment professions are slow to change. However, very gradually, modern allopathic medicine and attitudes are beginning to recognise the extraordinary wisdom and efficacy of ancient traditions such as acupuncture, light, colour and other therapies based on the understanding and treatment of the interaction of a person's electromagnetic subtle body and the immediate environment. These and many other 'complementary' therapies may soon become mainstream medical practice. In the meantime, we can help ourselves by learning how to detect the hazards and daily practise prudent avoidance.

Abnormalities, Radiation-Induced↗
PubMed2001

[Air travel--a disease risk? ].

Civil air traffic moves in an altitude that is dangerous for human beings without technical aids. Low temperature and humidity, reduced air pressure combined with oxygen pressure, seasonal depending high concentration of ozone and cosmic radiation may also be risk factors. Further risks on long haul flights may be jet lag, risk of economy class syndrome and contact with permethrin, because of disinsection before take-off out of tropical regions. The aim of an airline is to offer good cabin air quality, comfort and security for all passengers, may they be healthy, old, disabled or sick. Medical incidences on board arise and passengers expect modern equipment such as doctor's kit and defibrillators.

Aerospace Medicine↗
PubMed1997

Chromosomal aberrations in blood lymphocytes of astronauts after long-term space flights.

PURPOSE: To analyse lymphocyte chromosomes from astronauts of MIR and EUROMIR missions. MATERIALS AND METHODS: Peripheral lymphocytes from seven astronauts before and after space flights were cultured and analysed for structural chromosomal aberrations. RESULTS: Chromosome-type but not chromatid-type aberrations were significantly elevated after space flights when compared to pre-flight values. In one astronaut two rogue cells were found. CONCLUSIONS: Overall the frequencies of aberrations were found to be correlated with estimated absorbed cosmic radiation doses.

Astronauts↗
PubMed2005

Species selection for phytoremediation of 36Cl/35Cl using angiosperm phylogeny and inter-taxa differences in uptake.

High concentrations of 35Cl and the radioisotope 36Cl (produced naturally by cosmic radiation and anthropogenically by U fission and the use of neutron sources) can be problematic in soil, but are potentially amenable to phytoremediation if appropriate plants can be found. Here, results are reported that might aid the selection of plants with unusually high or low uptake of 36Cl A residual maximum likelihood analysis was used to estimate, from 13 experiments, relative 36Cl uptake by 106 species across the angiosperm phylogeny. Nested analysis of variance, coded using a recent angiosperm phylogeny, showed that there were significant inter-species differences in 36Cl uptake and that species behavior was not independent; but linked through theirphylogeny. Eudicots had significantly higher 36Cl uptake than Monocots and related clades and, in particular the Orders Caryophyllales, Apiales, and Cucurbitales had high uptake while the Poales, Lillales, Brassicales, and Fabales had low uptake. Overall, 35% of the inter-taxa variation in 36Cl was attributed to the taxonomic ranks of Order and above, a significant phylogenetic effect compared with other elements for which similar analyses have been published. The implications of these findings for selecting plants for phytoremediation of soil contaminated with 35/36Cl are discussed.

Chlorine↗