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At least 469 records · Page 26Linked to original sources
PubMed2002

Effect of high altitude on protein metabolism in Bolivian children.

In Bolivia, malnutrition in children is a major health problem that may be caused by inadequate protein, energy, and micronutrient intake; exposure to bacterial and parasitic infections; and life in a multistress environment (high altitude, cold, cosmic radiation, low ambient humidity). However, no data on protein absorption and utilization at high altitude were available. Therefore, we evaluated the effect of altitude on protein metabolism in Bolivian children. We measured protein utilization using leucine labeled with a stable isotope ((13)C) in two groups of healthy prepubertal children matched for age. Group 1 (n = 10) was examined at high altitude (HA) in La Paz (3600 m), and group 2 (n = 10) at low altitude (LA) in Santa Cruz (420 m). The nutritional status did not differ between groups but, as was to be expected, the HA group had higher hemoglobin concentration than the LA group. The children consumed casein that was intrinsically labeled with L-(1-(13)C) leucine and expired (13)CO(2) was analyzed. Samples of expired air were measured by isotope ratio mass spectrometer in Clermont-Ferrand. It was found that cumulative leucine oxidation ((13)CO(2)) at 300 min after ingestion was 19.7 +/- 4.9% at HA and 25.2 +/- 3.2% at LA. These results showed that protein absorption and/or utilization is significantly affected by altitude.

Altitude↗
PubMed2001

The response of the sievert instrument in neutron beams up to 180 MeV.

Measurements with a tissue-equivalent proportional counter (TEPC) using the variance-covariance method have been performed in neutron beams between 71 keV and 180 MeV and in the cosmic radiation reference field (CERF) at CERN. The results show that with appropriate linear QD(yD) relations, the ambient dose equivalent can be determined within about 55% in these beams. Build-up measurements show that wall thickness is not crucial for H* determinations at 60 and 180 MeV.

Brachytherapy↗
PubMed2004

Gamma dose rate calculation and mapping of piemonte (North-West Italy) from gamma spectrometry soil data.

In this study the air gamma dose rate map of Piemonte, a region in the North-West of Italy, was produced from gamma spectrometry soil data. Soil samples collected in 110 different sites of Piemonte were analysed with Hyperpure Germanium (HPGe) detectors (30% relative efficiency), which allow the evaluation of the activity concentrations of natural radionuclides and (137)Cs. Then, using the available mathematical models, the gamma absorbed dose rate in air due to radionuclides was calculated. The contribution of the cosmic radiation to the total absorbed dose rate, which depend on the site altitude was also evaluated and added to the soil contribution. Finally, the map of the whole region was obtained by fitting the dose rate values of the different sites with kriging algorithms.

Algorithms↗
PubMed2006

Bubble detector investigations in China.

Investigation on bubble detectors started in China in 1989. Five types of bubble detectors have been developed, with LET thresholds ranging from 0.05 to 6.04 MeV mg(-1) cm(2) at 25 degrees C. The neutron response of bubble detectors made with freon-12 has been investigated with mono-energetic neutrons from 20 keV to 19 MeV. Its effective threshold energy for neutron detection is approximately 100 keV at 28 degrees C. The response above this threshold is approximately 1.5 x 10(-4) (bubble cm(-2))/(n cm(-2)). Bubble detectors are unique not only for neutron dosimetry but also for monitoring and identifying high-energy heavy ions such as cosmic radiation in the space. High-energy heavy ion tracks in large size bubble detectors have been investigated in cooperation with scientists in Japan. The key parameter behind the thresholds of bubble detectors for track registration is the critical rate of energy loss. Three approaches to identify high-energy heavy ions with bubble detectors are suggested.

China↗
PubMed2004

Environmental health physics-50 years of progress.

Environmental health physics is an interdisciplinary field, involving study of the release, transport, and fate of radioactive material in the environment. Further, it addresses the interaction of humans with radioactive materials within the ambient (outdoor) environment and with the environments associated with modern technology and lifestyles. It also involves both naturally occurring and artificially produced radionuclides with the former generally being by far the highest source of exposure. In fact, doses from naturally occurring radionuclides are increasingly being used as a benchmark for the establishment of dose rate limits for people. Because of the pioneering work of early environmental health physicists, models exist today that can be used to assess the potential impacts of new nuclear facilities prior to their operation. In fact, these people represent the branch of the health physics profession who conducted environmental monitoring programs and performed the associated research studies that led to the identification of the principal radionuclides of interest, the major pathways and mechanisms through which they expose people, and the doses that may result from radioactive materials in the natural and technologically enhanced environments. One of their most important contributions was the identification and quantification of many of the key parameters that serve as input to such models. Monitoring of nuclear weapons development facilities used during and after World War II was the initial stimulus for the establishment of environmental health physics programs. Thereafter, these programs were expanded both nationally and globally, as a result of the atmospheric weapons testing programs of nations such as France, the People's Republic of China, the former Soviet Union, the United Kingdom, and the United States. Additional stimuli were provided by the development of the commercial nuclear power industry. Current environmental programs, particularly within the U.S., focus on decontamination and decommissioning of dormant facilities from these earlier defense and commercial programs. The range of the environmental health physics aspects of these activities is the subject of this paper. Presented at the end of the paper is a summary of some of the more important lessons that have been learned. As will be noted, this is an exciting field that will present challenges to health physicists for years to come.

Background Radiation↗
PubMed2005

Environmental health physics: 50 years of progress.

Environmental health physics is an interdisciplinary field, involving study of the release, transport, and fate of radioactive material in the environment. Further, it addresses the interaction of humans with radioactive materials within the ambient (outdoor) environment and with the environments associated with modern technology and lifestyles. It also involves both naturally occurring and artificially produced radionuclides with the former generally being by far the highest source of exposure. In fact, doses from naturally occurring radionuclides are increasingly being used as a benchmark for the establishment of dose rate limits for people. Because of the pioneering work of early environmental health physicists, models exist today that can be used to assess the potential impacts of new nuclear facilities prior to their operation. In fact, these people represent the branch of the health physics profession who conducted environmental monitoring programs and performed the associated research studies that led to the identification of the principal radionuclides of interest, the major pathways and mechanisms through which they expose people, and the doses that may result from radioactive materials in the natural and technologically enhanced environments. One of their most important contributions was the identification and quantification of many of the key parameters that serve as input to such models. Monitoring of nuclear weapons development facilities used during and after World War II was the initial stimulus for the establishment of environmental health physics programs. Thereafter, these programs were expanded both nationally and globally, as a result of the atmospheric weapons testing programs of nations such as France, the People's Republic of China, the former Soviet Union, the United Kingdom, and the United States. Additional stimuli were provided by the development of the commercial nuclear power industry. Current environmental programs, particularly within the U.S., focus on decontamination and decommissioning of dormant facilities from these earlier defense and commercial programs. The range of the environmental health physics aspects of these activities is the subject of this paper. Presented at the end of the paper is a summary of some of the more important lessons that have been learned. As will be noted, this is an exciting field that will present challenges to health physicists for years to come.

Background Radiation↗
PubMed1998

Mortality among US commercial pilots and navigators.

The airline industry may be an occupational setting with specific health risks. Two environmental agents to which flight crews are known to be exposed are cosmic radiation and magnetic fields generated by the aircraft's electrical system. Other factors to be considered are circadian disruption and conditions specific to air travel, such as noise, vibration, mild hypoxia, reduced atmospheric pressure, low humidity, and air quality. This study investigated mortality among US commercial pilots and navigators, using proportional mortality ratios for cancer and noncancer end points. Proportional cancer mortality ratios and mortality odds ratios were also calculated for comparison to the proportional mortality ratios for cancer causes of death. Results indicated that US pilots and navigators have experienced significantly increased mortality due to cancer of the kidney and renal pelvis, motor neuron disease, and external causes. In addition, increased mortality due to prostate cancer, brain cancer, colon cancer, and cancer of the lip, buccal cavity, and pharynx was suggested. Mortality was significantly decreased for 11 causes. To determine if these health outcomes are related to occupational exposures, it will be necessary to quantify each exposure separately, to study the potential synergy of effects, and to couple this information with disease data on an individual basis.

Aerospace Medicine↗
PubMed2001

Measurement of the cosmic-ray antiproton-to-proton abundance ratio between 4 and 50 GeV.

We present a new measurement of the antiproton-to-proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm(2). A total of 71 antiprotons were identified above the vertical geomagnetic cutoff rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.

Journal Article↗
PubMedDate not supplied

A retrospective cohort mortality study of Italian commercial airline cockpit crew and cabin attendants, 1965-96.

A retrospective cohort mortality study was conducted among Italian commercial flight personnel for the period 1965-1996. The cohort was composed of 3,022 male cockpit crew members and 3,418 male and 3,428 female cabin attendants. Cause-specific standardized mortality ratios (SMRs) and exact 95% confidence intervals (CIs) were calculated as estimates of the relative risk. Mortality from all cancers was less than expected for all categories (SMRs of 0.58 for male cockpit crew, 0.67 for male cabin attendants, and 0.90 for female cabin attendants). Among male flight personnel, the SMR for leukemia was somewhat elevated (SMR 1.73; 95% CI: 0.75-3.41) based on eight deaths, with a positive trend by length of employment (p = 0.046). Additionally, an excess of death by suicide was seen among female cabin attendants (SMR 3.38; 95% CI: 1.24-7.35). Other Italian studies of flight personnel are under way, including a detailed assessment of cosmic radiation exposure and investigations of non-radiation occupational risk factors and prevalence of nonfatal outcomes.

Adult↗
PubMed2026

Interpreting cancer genetics through a two-step "evolutionary cascade hypothesis": bridging neutral and selective perspectives.

BACKGROUND: DNA mutations are the fundamental engines of cancer, driving its initiation and progression. The forces that fuel malignancy are also the architects of evolution, shaping life through genetic variations. Mutations, in fact, can emerge naturally from endogenous processes, such as oxidative DNA damage or errors in replication, as well as induced by external factors, including cosmic radiation and chemical carcinogens. MAIN BODY: A key question in cancer research is whether tumor evolution is primarily governed by selective bottlenecks, neutral evolution, or dynamic genetic plasticity. In this work, we examine cancer as a disease driven by evolutionary processes rooted in fundamental biological requirements, including sustained proliferation and nutrient utilization. We hypothesize that the accumulation of mutations activates an evolutionary switch, enabling tumor cells to acquire an enhanced capacity for survival, adaptation, and growth at rates far exceeding typical evolutionary timescales. We propose the "evolutionary cascade hypothesis," a unifying framework that integrates these models into a coherent sequence. At its core lies the failure of DNA repair mechanisms, representing a critical transition in cancer progression. This shift marks the transition from an initial non-Darwinian, neutral phase to a Darwinian, more deterministic phase. CONCLUSIONS: As predictive models of tumor evolution advance through genomic big data and artificial intelligence-driven analysis, the future of cancer treatment may extend beyond targeting individual mutations to disrupting the underlying evolutionary mechanisms that sustain malignancy. This paradigm shift could redefine therapeutic strategies and ultimately improve patient outcomes.

Humans↗
PubMed1993

The carcinogenic effect of solar activity with different intensities on embryos.

The carcinogenic effects of solar activity with different intensities on embryos were studied epidemiologically. The study reveals that receiving a moderate amount of low level cosmic radiation at embryonic stage may reduce cancer occurrence later. This paper analyses and discusses the mechanisms of this hormetic effect.

China↗
PubMed2002

Influence of the shielding on the induction of chromosomal aberrations in human lymphocytes exposed to high-energy iron ions.

Computer code calculations based on biophysical models are commonly used to evaluate the effectiveness of shielding in reducing the biological damage caused by cosmic radiation in space flights. Biological measurements are urgently needed to benchmark the codes. We have measured the induction of chromosomal aberrations in human peripheral blood lymphocytes exposed in vitro to 56Fe-ion beams accelerated at the HIMAC synchrotron in Chiba. Isolated lymphocytes were exposed to the 500 MeV/n iron beam (dose range 0.1-1 Gy) after traversal of 0 to 8 g/cm2 of either PMMA (lucite, a common plastic material) or aluminum. Three PMMA shield thickness and one Al shield thickness were used. 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 yield of chromosomal aberrations per unit dose at the sample position was poorly dependent on the shield thickness and material. However, the yield of aberrations per unit ion incident on the shield was increased by the shielding. This increase is associated to the increased dose-rate measured behind the shield as compared to the direct beam. These preliminary results prove that shielding can increase the effectiveness of heavy ions, and the damage is dependent upon shield thickness and material.

Adult↗
PubMed2002

LET distributions measured at the CERF facility with the RRMD-III.

The LET distributions in front of the 80 cm-thick concrete side shield at the CERF facility were measured with a Si detector telescope (RRMD-III) covered with and without a 1 cm-thick acrylic plate. In these measurements, a slight difference between the LET distributions was seen as a result of recoil protons and/or carbon particles by neutrons. Also, the LET distributions are compared with the micro-dosimetric spectrum (i.e., lineal energy distribution) measured with a cylindrical TEPC under the same conditions.

Background Radiation↗
PubMed2001

Microflora investigation experiment.

Many microorganisms were isolated from condensed water, wiping and scratching of cabin wall and air sampler in Russian space station Mir by Russian astronauts Lazutkin et al. in February 1997 as part of NASDA "First MIR Utilization Space Experiment (JMIR)". For example, there were about 2 x 10(6) cells/ml in condensed water sample No. 1 isolated from the transfer-docking compartment of Crystal module. We tried the colony isolation, pure culturing and identification from these sampled microorganisms. After the bacteria separated from filamentous fungi and yeasts were observed using the phase contrast optical microscopy and gram stain method, twenty-one kinds of biochemical characters, e.g., oxidase test, activity of beta-galactosidase and fermentation of glucose etc., were investigated on the isolated bacteria. Then, we found Serratia liquefaciens and Yersinia enterocolitica and the chemoheterotroph Pseudomonadaceae, Stenotrophomonas maltophila. Furthermore, using ultraviolet (UV) lamp we tried the isolation of radioresistant bacteria, we found the radioresistant Sphingomonas paucimobilis (90.8% identification) by comparing with radioresistant Escherichia coli B/r strain. Considering Mir environment under cosmic radiation, this radioresistant S. paucimobilis might be the mutant from radiosensitive one. Following papers were published [see text].

Bacteria↗
PubMed1991

Space travel shortens diapause in gypsy moth eggs.

Field-collected and laboratory-reared gypsy moth eggs were exposed to microgravity, cosmic radiation, sub-freezing temperatures, unusual vibrations, and other extraterrestrial phenomena while they were sealed for 6 days, in January, in a Get-Away-Special (GAS) canister in the open bay of a NASA earth-orbiting spacecraft, the Columbia. Insects were not exposed to light after preparation for and during space flight. Under field conditions, out-of-doors, the eggs should have hatched in April, after 3-4 months of chilling temperatures and should not have hatched after the 6 days of chilling to -11 degrees C during flight in the Columbia spacecraft. However by April 1, more than 4000 larvae had hatched from eggs that had travelled in space, as opposed to approximately 350 from a similar number of control, earthbound eggs. These results indicate that the period of a circannual rhythm in field- and lab-reared insects had been shortened, presumably as result of exposure to microgravity, other factors associated with space flight, and/or conditions of outer space. These results suggest that it may be possible to develop methods for rearing the gypsy moth year round, without the necessity of three months chilling interspersed in the development process. This, in turn, would facilitate production of large numbers of insects for sterile male release or for use as a rearing medium for parasites, predators and pathogens of the gypsy moth.

Animals↗