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1.
Int J Radiat Biol ; 98(3): 395-403, 2022.
Article in English | MEDLINE | ID: mdl-34270368

ABSTRACT

PURPOSE: My journey to the stars began as I - along with the whole world - stood still and watched Neil Armstrong take those first small steps on the Moon. Fast forward 50 years and NASA astronauts Scott Kelly and Christina Koch each spend nearly a year in space aboard the International Space Station (ISS), a remarkable multinational collaborative project and floating U.S. National Laboratory that has supported continuous human presence in low Earth orbit for the past 20 years. Marking a new era of human space exploration, the first commercial rocket, SpaceX Falcon 9, recently launched NASA astronauts Doug Hurley and Bob Behnken in the Crew Dragon spacecraft Endeavor to the ISS and returned safely to Earth. NASA and its commercial partners are rapidly advancing innovative space technologies, and with the recently announced Artemis team of astronauts, plans to send the first woman and next man back to the moon and establish sustainable exploration by the end of the decade. Humankind will then be poised to take the next giant leap - pioneering human exploration of Mars. CONCLUSIONS: Historically, fewer than 600 individuals have participated in spaceflight, the vast majority of whom have been middle aged males (35-55 years) on short duration missions (less than 20 days). Thus, as the number and diversity of space travelers increase, a better understanding of how long-duration spaceflight affects human health is essential to maintaining individual astronaut performance during, and improving disease and aging trajectories following, future exploration missions. Here, I review findings from our NASA Twins Study and Telomeres investigations, highlighting potential mechanistic roles of chronic space radiation exposure in changes in telomere length and persistent DNA damage responses associated with long-duration spaceflight. Importantly, similar trends were observed in prostate cancer patients undergoing intensity-modulated radiation therapy (IMRT), additional support specifically for the role of radiation exposure. Individual differences in response were also observed in both cohorts, underscoring the importance of developing personalized approaches for evaluating human health effects and long-term outcomes associated with radiation exposures, whether on Earth or living in the extreme environment of space.


Subject(s)
Aging , Space Flight , Female , Humans , Laboratories , Male , Middle Aged , Telomere
2.
Genome Res ; 31(7): 1269-1279, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34162698

ABSTRACT

Telomeres are regions of repetitive nucleotide sequences capping the ends of eukaryotic chromosomes that protect against deterioration, and whose lengths can be correlated with age and adverse health risk factors. Yet, given their length and repetitive nature, telomeric regions are not easily reconstructed from short-read sequencing, thus making telomere sequencing, mapping, and variant resolution challenging problems. Recently, long-read sequencing, with read lengths measuring in hundreds of kilobase pairs, has made it possible to routinely read into telomeric regions and inspect their sequence structure. Here, we describe a framework for extracting telomeric reads from whole-genome single-molecule sequencing experiments, including de novo identification of telomere repeat motifs and repeat types, and also describe their sequence variation. We find that long, complex telomeric stretches and repeats can be accurately captured with long-read sequencing, observe extensive sequence heterogeneity of human telomeres, discover and localize noncanonical telomere sequence motifs (both previously reported, as well as novel), and validate them in short-read sequence data. These data reveal extensive intra- and inter-population diversity of repeats in telomeric haplotypes, reveal higher paternal inheritance of telomeric variants, and represent the first motif composition maps of multi-kilobase-pair human telomeric haplotypes across three distinct ancestries (Ashkenazi, Chinese, and Utah), which can aid in future studies of genetic variation, aging, and genome biology.

3.
Biomater Sci ; 9(10): 3576-3602, 2021 May 18.
Article in English | MEDLINE | ID: mdl-34008586

ABSTRACT

The outstretched applications of biosensors in diverse domains has become the reason for their attraction for scientific communities. Because they are analytical devices, they can detect both quantitative and qualitative biological components through the generation of detectable signals. In the recent past, biosensors witnessed significant changes and developments in their design as well as features. Nanotechnology has revolutionized sensing phenomena by increasing biodiagnostic capacity in terms of specificity, size, and cost, resulting in exceptional sensitivity and flexibility. The steep increase of non-communicable diseases across the world has emerged as a matter of concern. In parallel, the abrupt outbreak of communicable diseases poses a serious threat to mankind. For decreasing the morbidity and mortality associated with various communicable and non-communicable diseases, early detection and subsequent treatment are indispensable. Detection of different biological markers generates quantifiable signals that can be electrochemical, mass-based, optical, thermal, or piezoelectric. Speculating on the incumbent applicability and versatility of nano-biosensors in large disciplines, this review highlights different types of biosensors along with their components and detection mechanisms. Moreover, it deals with the current advancements made in biosensors and the applications of nano-biosensors in detection of various non-communicable and communicable diseases, as well as future prospects of nano-biosensors for diagnostics.


Subject(s)
Biosensing Techniques , Communicable Diseases , Biomarkers , Communicable Diseases/diagnosis , Humans , Nanotechnology
4.
Neurosci Biobehav Rev ; 127: 307-331, 2021 08.
Article in English | MEDLINE | ID: mdl-33915203

ABSTRACT

Multi-year crewed space exploration missions are now on the horizon; therefore, it is important that we understand and mitigate the physiological effects of spaceflight. The spaceflight hazards-radiation, isolation, confinement, and altered gravity-have the potential to contribute to neuroinflammation and produce long-term cognitive and behavioral effects-while the fifth hazard, distance from earth, limits capabilities to mitigate these risks. Accumulated evidence suggests that nutrition has an important role in optimizing cognition and reducing the risk of neurodegenerative diseases caused by neuroinflammation. Here we review the nutritional perspective of how these spaceflight hazards affect the astronaut's brain, behavior, performance, and sensorimotor function. We also assess potential nutrient/nutritional countermeasures that could prevent or mitigate spaceflight risks and ensure that crewmembers remain healthy and perform well during their missions. Just as history has taught us the importance of nutrition in terrestrial exploration, we must understand the role of nutrition in the development and mitigation of spaceflight risks before humans can successfully explore beyond low-Earth orbit.


Subject(s)
Astronauts , Space Flight , Brain , Cognition , Humans
5.
Sci Rep ; 11(1): 5293, 2021 03 05.
Article in English | MEDLINE | ID: mdl-33674665

ABSTRACT

Space radiation consists of energetic protons and other heavier ions. During the International Space Station program, chromosome aberrations in lymphocytes of astronauts have been analyzed to estimate received biological doses of space radiation. More specifically, pre-flight blood samples were exposed ex vivo to varying doses of gamma rays, while post-flight blood samples were collected shortly and several months after landing. Here, in a study of 43 crew-missions, we investigated whether individual radiosensitivity, as determined by the ex vivo dose-response of the pre-flight chromosome aberration rate (CAR), contributes to the prediction of the post-flight CAR incurred from the radiation exposure during missions. Random-effects Poisson regression was used to estimate subject-specific radiosensitivities from the preflight dose-response data, which were in turn used to predict post-flight CAR and subject-specific relative biological effectiveness (RBEs) between space radiation and gamma radiation. Covariates age, gender were also considered. Results indicate that there is predictive value in background CAR as well as radiosensitivity determined preflight for explaining individual differences in post-flight CAR over and above that which could be explained by BFO dose alone. The in vivo RBE for space radiation was estimated to be approximately 3 relative to the ex vivo dose response to gamma irradiation. In addition, pre-flight radiosensitivity tended to be higher for individuals having a higher background CAR, suggesting that individuals with greater radiosensitivity can be more sensitive to other environmental stressors encountered in daily life. We also noted that both background CAR and radiosensitivity tend to increase with age, although both are highly variable. Finally, we observed no significant difference between the observed CAR shortly after mission and at > 6 months post-mission.

6.
Cell Rep ; 33(10): 108457, 2020 12 08.
Article in English | MEDLINE | ID: mdl-33242406

ABSTRACT

Telomere length dynamics and DNA damage responses were assessed before, during, and after one-year or shorter duration missions aboard the International Space Station (ISS) in a comparatively large cohort of astronauts (n = 11). Although generally healthy individuals, astronauts tended to have significantly shorter telomeres and lower telomerase activity than age- and sex-matched ground controls before and after spaceflight. Although telomeres were longer during spaceflight irrespective of mission duration, telomere length shortened rapidly upon return to Earth, and overall astronauts had shorter telomeres after spaceflight than they did before; inter-individual differences were identified. During spaceflight, all crewmembers experienced oxidative stress, which positively correlated with telomere length dynamics. Significantly increased frequencies of chromosomal inversions were observed during and after spaceflight; changes in cell populations were also detected. We propose a telomeric adaptive response to chronic oxidative damage in extreme environments, whereby the telomerase-independent Alternative Lengthening of Telomeres (ALT) pathway is transiently activated in normal somatic cells.


Subject(s)
DNA Repair/physiology , Telomere Homeostasis/physiology , Weightlessness/adverse effects , Adult , Astronauts , DNA/chemistry , DNA/radiation effects , DNA Damage/physiology , DNA Repair/radiation effects , Female , Humans , Male , Middle Aged , Oxidative Stress/physiology , Space Flight , Telomerase/metabolism , Telomere/metabolism , Telomere/physiology , Telomere Homeostasis/radiation effects , Time Factors
7.
Cell Rep ; 33(10): 108435, 2020 12 08.
Article in English | MEDLINE | ID: mdl-33242411

ABSTRACT

Telomeres, repetitive terminal features of chromosomes essential for maintaining genome integrity, shorten with cell division, lifestyle factors and stresses, and environmental exposures, and so they provide a robust biomarker of health, aging, and age-related diseases. We assessed telomere length dynamics (changes over time) in three unrelated astronauts before, during, and after 1-year or 6-month missions aboard the International Space Station (ISS). Similar to our results for National Aeronautics and Space Administration's (NASA's) One-Year Mission twin astronaut (Garrett-Bakelman et al., 2019), significantly longer telomeres were observed during spaceflight for two 6-month mission astronauts. Furthermore, telomere length shortened rapidly after return to Earth for all three crewmembers and, overall, telomere length tended to be shorter after spaceflight than before spaceflight. Consistent with chronic exposure to the space radiation environment, signatures of persistent DNA damage responses were also detected, including mitochondrial and oxidative stress, inflammation, and telomeric and chromosomal aberrations, which together provide potential mechanistic insight into spaceflight-specific telomere elongation.


Subject(s)
DNA Damage/genetics , DNA Repair/physiology , Telomere/genetics , Adult , Astronauts , DNA/genetics , DNA/radiation effects , DNA Breaks, Double-Stranded , DNA Damage/radiation effects , DNA Repair/genetics , DNA Repair/radiation effects , Dose-Response Relationship, Radiation , Extraterrestrial Environment , Female , Humans , Male , Space Flight , Telomere/metabolism , Telomere/radiation effects , Time Factors , Weightlessness/adverse effects
8.
J Neurophysiol ; 123(5): 2037-2063, 2020 05 01.
Article in English | MEDLINE | ID: mdl-32292116

ABSTRACT

Space travel presents a number of environmental challenges to the central nervous system, including changes in gravitational acceleration that alter the terrestrial synergies between perception and action, galactic cosmic radiation that can damage sensitive neurons and structures, and multiple factors (isolation, confinement, altered atmosphere, and mission parameters, including distance from Earth) that can affect cognition and behavior. Travelers to Mars will be exposed to these environmental challenges for up to 3 years, and space-faring nations continue to direct vigorous research investments to help elucidate and mitigate the consequences of these long-duration exposures. This article reviews the findings of more than 50 years of space-related neuroscience research on humans and animals exposed to spaceflight or analogs of spaceflight environments, and projects the implications and the forward work necessary to ensure successful Mars missions. It also reviews fundamental neurophysiology responses that will help us understand and maintain human health and performance on Earth.


Subject(s)
Astronauts , Central Nervous System/physiology , Emotions/physiology , Mars , Psychomotor Performance/physiology , Space Flight , Vestibule, Labyrinth/physiology , Weightlessness , Animals , Humans , Weightlessness/adverse effects
9.
Science ; 364(6436)2019 04 12.
Article in English | MEDLINE | ID: mdl-30975860

ABSTRACT

To understand the health impact of long-duration spaceflight, one identical twin astronaut was monitored before, during, and after a 1-year mission onboard the International Space Station; his twin served as a genetically matched ground control. Longitudinal assessments identified spaceflight-specific changes, including decreased body mass, telomere elongation, genome instability, carotid artery distension and increased intima-media thickness, altered ocular structure, transcriptional and metabolic changes, DNA methylation changes in immune and oxidative stress-related pathways, gastrointestinal microbiota alterations, and some cognitive decline postflight. Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within 6 months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. These multiomic, molecular, physiological, and behavioral datasets provide a valuable roadmap of the putative health risks for future human spaceflight.


Subject(s)
Adaptation, Physiological , Astronauts , Space Flight , Adaptive Immunity , Body Weight , Carotid Arteries/diagnostic imaging , Carotid Intima-Media Thickness , DNA Damage , DNA Methylation , Gastrointestinal Microbiome , Genomic Instability , Humans , Male , Telomere Homeostasis , Time Factors , United States , United States National Aeronautics and Space Administration
10.
Artif Cells Nanomed Biotechnol ; 46(sup2): 1053-1062, 2018.
Article in English | MEDLINE | ID: mdl-29879850

ABSTRACT

Nanodrug delivery systems sometimes referred to as nanocarriers (NCs) are nanoengineered biocompatible materials or devices, which in conjugation with desired bioactive compounds plays an indispensable functional role in the field of pharmaceutical and allied sciences. The diversified ability of this bioengineered colloidal or noncolloidal molecule to breach the biological barriers to reach the targeted location in the biological system uplifts its other versatile natures of mono- or polydispersity in biodistribution. Furthermore, its nontoxicity and biodegradability result in making it a unique candidate for its purpose as drug delivery system. A number of different conjugations of chemical and biological substances are currently implemented for the synthesis of this biofunctional hybrid nanomaterial by simple methods. The use of these bioconjugated as a nanoparticulated system is currently being used for the treatment of various deadly incurable infectious diseases such as tuberculosis and disorders such as diabetes and cancers of various forms. Henceforth, the objective of the present review article is to provide overviews of the diversified and types of nanoparticulated systems, their beneficial as well as deleterious impacts along with the future prospect of nanodrug delivery system based on present status.


Subject(s)
Drug Carriers/chemistry , Nanostructures/chemistry , Humans
11.
PLoS One ; 11(4): e0153998, 2016.
Article in English | MEDLINE | ID: mdl-27111667

ABSTRACT

The biological effects of high charge and energy (HZE) particle exposures are of interest in space radiation protection of astronauts and cosmonauts, and estimating secondary cancer risks for patients undergoing Hadron therapy for primary cancers. The large number of particles types and energies that makeup primary or secondary radiation in HZE particle exposures precludes tumor induction studies in animal models for all but a few particle types and energies, thus leading to the use of surrogate endpoints to investigate the details of the radiation quality dependence of relative biological effectiveness (RBE) factors. In this report we make detailed RBE predictions of the charge number and energy dependence of RBE's using a parametric track structure model to represent experimental results for the low dose response for chromosomal exchanges in normal human lymphocyte and fibroblast cells with comparison to published data for neoplastic transformation and gene mutation. RBE's are evaluated against acute doses of γ-rays for doses near 1 Gy. Models that assume linear or non-targeted effects at low dose are considered. Modest values of RBE (<10) are found for simple exchanges using a linear dose response model, however in the non-targeted effects model for fibroblast cells large RBE values (>10) are predicted at low doses <0.1 Gy. The radiation quality dependence of RBE's against the effects of acute doses γ-rays found for neoplastic transformation and gene mutation studies are similar to those found for simple exchanges if a linear response is assumed at low HZE particle doses. Comparisons of the resulting model parameters to those used in the NASA radiation quality factor function are discussed.


Subject(s)
Chromosomes , Cosmic Radiation , Neoplasms/physiopathology , Dose-Response Relationship, Radiation , Humans , Neoplasms/genetics , Relative Biological Effectiveness
12.
Front Oncol ; 5: 226, 2015.
Article in English | MEDLINE | ID: mdl-26539409

ABSTRACT

We have investigated chromosome exchanges induced in human cells by seven different energies of protons (5-2500 MeV) with LET values ranging from 0.2 to 8 keV/µm. Human lymphocytes were irradiated in vitro and chromosome damage was assessed using three-color fluorescence in situ hybridization chromosome painting in chemically condensed chromosomes collected during the first cell division post irradiation. The relative biological effectiveness (RBE) was calculated from the initial slope of the dose-response curve for chromosome exchanges with respect to low dose and low dose-rate γ-rays (denoted as RBEmax), and relative to acute doses of γ-rays (denoted as RBEγAcute). The linear dose-response term was similar for all energies of protons, suggesting that the decrease in LET with increasing proton energy was balanced by the increase in dose from the production of nuclear secondaries. Secondary particles increase slowly above energies of a few hundred megaelectronvolts. Additional studies of 50 g/cm(2) aluminum shielded high-energy proton beams showed minor differences compared to the unshielded protons and lower RBE values found for shielded in comparison to unshielded beams of 2 or 2.5 GeV. All energies of protons produced a much higher percentage of complex-type chromosome exchanges when compared to acute doses of γ-rays. The implications of these results for space radiation protection and proton therapy are discussed.

13.
Radiat Res ; 182(4): 368-79, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25229974

ABSTRACT

The assumption of a linear dose response used to describe the biological effects of high-LET radiation is fundamental in radiation protection methodologies. We investigated the dose response for chromosomal aberrations for exposures corresponding to less than one particle traversal per cell nucleus by high-energy charged (HZE) nuclei. Human fibroblast and lymphocyte cells were irradiated with several low doses of <0.1 Gy, and several higher doses of up to 1 Gy with oxygen (77 keV/µm), silicon (99 keV/µm) or Fe (175 keV/µm), Fe (195 keV/µm) or Fe (240 keV/µm) particles. Chromosomal aberrations at first mitosis were scored using fluorescence in situ hybridization (FISH) with chromosome specific paints for chromosomes 1, 2 and 4 and DAPI staining of background chromosomes. Nonlinear regression models were used to evaluate possible linear and nonlinear dose-response models based on these data. Dose responses for simple exchanges for human fibroblasts irradiated under confluent culture conditions were best fit by nonlinear models motivated by a nontargeted effect (NTE). The best fits for dose response data for human lymphocytes irradiated in blood tubes were a linear response model for all particles. Our results suggest that simple exchanges in normal human fibroblasts have an important NTE contribution at low-particle fluence. The current and prior experimental studies provide important evidence against the linear dose response assumption used in radiation protection for HZE particles and other high-LET radiation at the relevant range of low doses.


Subject(s)
Cell Nucleus/genetics , Cell Nucleus/radiation effects , Chromosome Aberrations/radiation effects , Cosmic Radiation/adverse effects , Dose-Response Relationship, Radiation , Endpoint Determination , Fibroblasts/cytology , Fibroblasts/radiation effects , Humans , Linear Energy Transfer
14.
Radiat Res ; 181(3): 284-92, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24611656

ABSTRACT

We have developed a model that can simulate the yield of radiation-induced chromosomal aberrations (CAs) and unrejoined chromosome breaks in normal and repair-deficient cells. The model predicts the kinetics of chromosomal aberration formation after exposure in the G0/G1 phase of the cell cycle to either low- or high-LET radiation. A previously formulated model based on a stochastic Monte Carlo approach was updated to consider the time dependence of DNA double-strand break (DSB) repair (proper or improper), and different cell types were assigned different kinetics of DSB repair. The distribution of the DSB free ends was derived from a mechanistic model that takes into account the structure of chromatin and DSB clustering from high-LET radiation. The kinetics of chromosomal aberration formation were derived from experimental data on DSB repair kinetics in normal and repair-deficient cell lines. We assessed different types of chromosomal aberrations with the focus on simple and complex exchanges, and predicted the DSB rejoining kinetics and misrepair probabilities for different cell types. The results identify major cell-dependent factors, such as a greater yield of chromosome misrepair in ataxia telangiectasia (AT) cells and slower rejoining in Nijmegen (NBS) cells relative to the wild-type. The model's predictions suggest that two mechanisms could exist for the inefficiency of DSB repair in AT and NBS cells, one that depends on the overall speed of joining (either proper or improper) of DNA broken ends, and another that depends on geometric factors, such as the Euclidian distance between DNA broken ends, which influences the relative frequency of misrepair.


Subject(s)
Chromosome Aberrations/radiation effects , DNA Repair/radiation effects , Models, Biological , Cell Line , DNA Breaks, Double-Stranded/radiation effects , Humans , Kinetics
15.
Radiat Environ Biophys ; 53(2): 255-63, 2014 May.
Article in English | MEDLINE | ID: mdl-24477407

ABSTRACT

Chromosome aberrations in blood lymphocytes provide a useful measure of past exposure to ionizing radiation. Despite the widespread and successful use of the dicentric assay for retrospective biodosimetry, the approach suffers substantial drawbacks, including the fact that dicentrics in circulating blood have a rather short half-life (roughly 1-2 years by most estimates). So-called symmetrical aberrations such as translocations are far more stable in that regard, but their high background frequency, which increases with age, also makes them less than ideal for biodosimetry. We developed a cytogenetic assay for potential use in retrospective biodosimetry that is based on the detection of chromosomal inversions, another symmetrical aberration whose transmissibility (stability) is also ostensibly high. Many of the well-known difficulties associated with inversion detection were circumvented through the use of directional genomic hybridization, a method of molecular cytogenetics that is less labor intensive and better able to detect small chromosomal inversions than other currently available approaches. Here, we report the dose-dependent induction of inversions following exposure to radiations with vastly different ionization densities [i.e., linear energy transfer (LET)]. Our results show a dramatic dose-dependent difference in the yields of inversions induced by low-LET gamma rays, as compared to more damaging high-LET charged particles similar to those encountered in deep space.


Subject(s)
Chromosome Inversion/radiation effects , Environmental Exposure/adverse effects , Environmental Exposure/analysis , Radiometry/methods , Chromosome Breakage/radiation effects , Chromosomes, Human, Pair 3/genetics , Chromosomes, Human, Pair 3/radiation effects , Dose-Response Relationship, Radiation , Gamma Rays/adverse effects , Humans , Linear Energy Transfer , Nucleic Acid Hybridization , Retrospective Studies
16.
Radiat Res ; 180(1): 25-33, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23692480

ABSTRACT

We have investigated how radiation quality affects the induction of chromosomal aberrations in human cells. Human lymphocytes were irradiated in vitro with various energies of accelerated high charge and energy (HZE) particles including oxygen, neon, silicon, titanium and iron. Chromosome damage was assessed using three-color FISH chromosome painting in chemically induced premature chromosome condensation samples collected at first cell division after irradiation. The LET values for these particles ranged from 30 to 195 keV/µm, and their energies ranged from about 55 MeV/u to more than 1,000 MeV/u. The 89 and 142 MeV/u neon particles produced the most simple-type reciprocal exchanges per unit dose. For complex-type exchanges, 64 MeV/u neon and 450 MeV/u iron were equally effective and induced the greatest amount of complex damage. Track structure models predict that at a fixed value of LET, particles with lower charge number (Z) will have a higher biological effectiveness compared to particles with a higher Z, and that a saturation cross section will be observed for different radiation qualities. Our results are consistent with model expectations within the limitation of experimental error, and provide the most extensive data that have been reported on the radiation quality dependences of chromosomal aberrations.


Subject(s)
Chromosome Aberrations/radiation effects , Linear Energy Transfer , Lymphocytes/radiation effects , Relative Biological Effectiveness , Cells, Cultured , Cosmic Radiation , Dose-Response Relationship, Radiation , Humans , In Situ Hybridization, Fluorescence
17.
Mutat Res ; 756(1-2): 101-7, 2013 Aug 30.
Article in English | MEDLINE | ID: mdl-23688614

ABSTRACT

We have studied the induction of chromosome aberrations in human fibroblasts exposed in G0/G1 to X-rays or heavy ions to study the influence of G1 cell cycle arrest. Confluent normal fibroblasts were exposed to X-rays or accelerated particles with different LET values and chromosome aberrations were investigated in the first G0/G1 and G2//M phase. The particles used here were 490MeV/nucleon Si, 500MeV/nucleon Fe, and 200MeV/nucleon Fe ions. Cells were subcultured 24h after exposure and premature chromosome condensation (PCC) was performed by fusion-induced method for analysis of G0/G1 cells, and chemically-induced method for analysis of G2 and metaphase cells. Chromosome damage was assessed in chromosomes 1 and 3 using whole chromosome fluorescence in situ hybridization (FISH). Cell cycle was analyzed by flow cytometry at different incubation times following subculture. After irradiation with 2Gy of high-LET particles, the yields of chromosome aberrations and fragments were significantly higher in G0/G1 phase than in G2/M phase, whereas similar yields of damage were measured in both phases after exposure to X-rays. In contrast, the yield of misrepair, assessed by the number of color junctions, was similar in the G0/G1 and G2/M phases after exposure to either X-rays or high-LET particles. The yields of chromosome aberrations, fragments, and color junctions in both the G0/G1 and the G2/M phases, increased with LET up to 200keV/µm, then decreased for 440keV/µm Fe particles. A good correlation was found between chromosome aberrations in both G0/G1 and G2/M cells and survival fractions after 2Gy of different LET radiations, although the slopes were steeper for the G0/G1 cells. Flow cytometry analysis indicated that high-LET particles induce more non cycling G0/G1 cells within 48h of subculture than X-rays, suggesting that chromosome aberrations scored at the G2/M phase may not accurately describe the true radiation effect.


Subject(s)
Cell Cycle/genetics , Cell Cycle/radiation effects , Chromosome Aberrations/radiation effects , Fibroblasts/radiation effects , Skin/radiation effects , Cells, Cultured , Fibroblasts/cytology , Fibroblasts/metabolism , Flow Cytometry , Humans , Image Processing, Computer-Assisted , In Situ Hybridization, Fluorescence , Linear Energy Transfer , Skin/cytology , Skin/metabolism , X-Rays
18.
J Radiat Res ; 54(6): 989-97, 2013 Nov 01.
Article in English | MEDLINE | ID: mdl-23674607

ABSTRACT

Potentially lethal damage (PLD) and its repair (PLDR) were studied in confluent human fibroblasts by analyzing the kinetics of chromosome break rejoining after X-ray or heavy-ion exposures. Cells were either held in the non-cycling G0 phase of the cell cycle for 12 h, or forced to proliferate immediately after irradiation. Fusion premature chromosome condensation (PCC) was combined with fluorescence in situ hybridization (FISH) to study chromosomal aberrations in interphase. The culture condition had no impact on the rejoining kinetics of PCC breaks during the 12 h after X-ray or heavy-ion irradiation. However, 12 h after X-ray and silicon irradiation, cycling cells had more chromosome exchanges than non-cycling cells. After 6 Gy X-rays, the yield of exchanges in cycling cells was 2.8 times higher than that in non-cycling cells, and after 2 Gy of 55 keV/µm silicon ions the yield of exchanges in cycling cells was twice that of non-cycling cells. In contrast, after exposure to 2 Gy 200-keV/µm or 440-keV/µm iron ions the yield of exchanges was similar in non-cycling and cycling cells. Since the majority of repair in G0/G1 occurs via the non-homologous end joining process (NHEJ), increased PLDR in X-ray and silicon-ion irradiated cells may result from improved cell cycle-specific rejoining fidelity through the NHEJ pathway, which is not the case in high-LET iron-ion irradiated cells.


Subject(s)
Apoptosis/genetics , Cell Cycle/physiology , Chromosome Aberrations/radiation effects , DNA End-Joining Repair/genetics , DNA End-Joining Repair/radiation effects , Fibroblasts/cytology , Fibroblasts/physiology , Linear Energy Transfer/radiation effects , Apoptosis/radiation effects , Cell Cycle/radiation effects , Cells, Cultured , Dose-Response Relationship, Radiation , Fibroblasts/radiation effects , Humans , Kinetics , Linear Energy Transfer/genetics , Radiation Dosage
19.
Radiat Res ; 177(6): 727-37, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22490019

ABSTRACT

We present a computational model for calculating the yield of radiation-induced chromosomal aberrations in human cells based on a stochastic Monte Carlo approach and calibrated using the relative frequencies and distributions of chromosomal aberrations reported in the literature. A previously developed DNA-fragmentation model for high- and low-LET radiation called the NASARadiationTrackImage model was enhanced to simulate a stochastic process of the formation of chromosomal aberrations from DNA fragments. The current version of the model gives predictions of the yields and sizes of translocations, dicentrics, rings, and more complex-type aberrations formed in the G(0)/G(1) cell cycle phase during the first cell division after irradiation. As the model can predict smaller-sized deletions and rings (<3 Mbp) that are below the resolution limits of current cytogenetic analysis techniques, we present predictions of hypothesized small deletions that may be produced as a byproduct of properly repaired DNA double-strand breaks (DSB) by nonhomologous end-joining. Additionally, the model was used to scale chromosomal exchanges in two or three chromosomes that were obtained from whole-chromosome FISH painting analysis techniques to whole-genome equivalent values.


Subject(s)
Chromosome Aberrations/radiation effects , Computer Simulation , Linear Energy Transfer , Models, Biological , Alpha Particles/adverse effects , Chromosomes, Human/genetics , Chromosomes, Human/radiation effects , Dose-Response Relationship, Radiation , Humans , In Situ Hybridization, Fluorescence , Male
20.
Cochrane Database Syst Rev ; (3): CD005106, 2012 Mar 14.
Article in English | MEDLINE | ID: mdl-22419306

ABSTRACT

BACKGROUND: Neck disorders are common, disabling, and costly. The effectiveness of patient education strategies is unclear. OBJECTIVES: To assess the short- to long-term effects of therapeutic patient education (TPE) strategies on pain, function, disability, quality of life, global perceived effect, patient satisfaction, knowledge transfer, or behaviour change in adults with neck pain associated with whiplash or non-specific and specific mechanical neck pain with or without radiculopathy or cervicogenic headache. SEARCH METHODS: We searched computerised bibliographic databases (inception to 11 July 2010). SELECTION CRITERIA: Eligible studies were randomised controlled trials (RCT) investigating the effectiveness of TPE for acute to chronic neck pain. DATA COLLECTION AND ANALYSIS: Paired independent review authors conducted selection, data abstraction, and 'Risk of bias' assessment. We calculated risk ratio (RR) and standardised mean differences (SMD). Heterogeneity was assessed; no studies were pooled. MAIN RESULTS: Of the 15 selected trials, three were rated low risk of bias. Three TPE themes emerged.Advice focusing on activation: There is moderate quality evidence (one trial, 348 participants) that an educational video of advice focusing on activation was more beneficial for acute whiplash-related pain when compared with no treatment at intermediate-term [RR 0.79 (95% confidence interval (CI) 0.59 to 1.06)] but not long-term follow-up [0.89 (95% CI, 0.65 to 1.21)]. There is low quality evidence (one trial, 102 participants) that a whiplash pamphlet on advice focusing on activation is less beneficial for pain reduction, or no different in improving function and global perceived improvement from generic information given out in emergency care (control) for acute whiplash at short- or intermediate-term follow-up. Low to very low quality evidence (nine trials using diverse educational approaches) showed either no evidence of benefit or difference for varied outcomes. Advice focusing on pain & stress coping skills and workplace ergonomics: Very low quality evidence (three trials, 243 participants) favoured other treatment or showed no difference spanning numerous follow-up periods and disorder subtypes.  Low quality evidence (one trial, 192 participants) favoured specific exercise training for chronic neck pain at short-term follow-up.Self-care strategies: Very low quality evidence (one trial, 58 participants) indicated that self-care strategies did not relieve pain for acute to chronic neck pain at short-term follow-up. AUTHORS' CONCLUSIONS: With the exception of one trial, this review has not shown effectiveness for educational interventions, including advice to activate, advice on stress-coping skills, workplace ergonomics and self-care strategies. Future research should be founded on sound adult learning theory and learning skill acquisition.


Subject(s)
Neck Pain/therapy , Patient Education as Topic/methods , Whiplash Injuries/complications , Adaptation, Psychological , Adult , Combined Modality Therapy , Humans , Neck Pain/etiology , Radiculopathy/complications , Randomized Controlled Trials as Topic , Rest , Self Care/methods , Treatment Outcome , Whiplash Injuries/therapy
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