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Spectra and frequencies of spontaneous and X-ray-induced somatic mutations were revealed with mouse long-term hematopoietic stem cells (LT-HSCs) by whole-genome sequencing of clonal cell populations propagated in vitro from single isolated LT-HSCs. SNVs and small indels were the most common types of somatic mutations, and increased up to twofold to threefold by whole-body X-irradiation. Base substitution patterns in the SNVs suggested a role of reactive oxygen species in radiation mutagenesis, and signature analysis of single base substitutions (SBS) revealed a dose-dependent increase of SBS40. Most of spontaneous small deletions were shrinkage of tandem repeats, and X-irradiation specifically induced small deletions out of tandem repeats (non-repeat deletions). Presence of microhomology sequences in non-repeat deletions suggested involvement of microhomology mediated end-joining repair mechanisms as well as nonhomologous end-joining in radiation-induced DNA damages. We also identified multisite mutations and structural variants (SV), i.e., large indels, inversions, reciprocal translocations, and complex variants. The radiation-specificity of each mutation type was evaluated from the spontaneous mutation rate and the per-Gy mutation rate estimated by linear regression, and was highest with non-repeat deletions without microhomology, followed by those with microhomology, SV except retroelement insertions, and multisite mutations; these types were thus revealed as mutational signatures of ionizing radiation. Further analysis of somatic mutations in multiple LT-HSCs indicated that large fractions of postirradiation LT-HSCs originated from single LT-HSCs that survived the irradiation and then expanded in vivo to confer marked clonality to the entire hematopoietic system, with varying clonal expansion and dynamics depending on radiation dose and fractionation.

Summary Red blood cell distribution width (RDW), which generally increases with age, is a risk marker for morbidity and mortality in various diseases. We investigated the association between elevated RDW and prior radiation exposure by examining longitudinal RDW changes in 4204 atomic‐bomb survivors over 15 years. A positive association was found between RDW and radiation dose, wherein RDW increased by 0·18%/Gy. This radiation‐associated effect increased as the participants aged. Elevated RDW was also associated with higher all‐cause mortality. The biological mechanisms underlying these observed associations merit further investigation.

Prohydrojasmon (PDJ), an analog of jasmonic acid (JA), was found to induce direct and indirect defenses against herbivores in non-infested plants. To test whether PDJ can be used for pest control in crop production, we conducted experiments in pesticide-free Japanese radish fields from October 4 to December 12 in 2015. Twenty-four Japanese radish plants in three plots were treated with a 100 times-diluted commercial formulation (5%) of PDJ (treated plants), and 24 plants in three different plots were treated with water (control plants) until November 29 every week. Throughout the observation period, the number of aphids, leaf-mining fly larvae, vegetable weevils, and thrips was significantly lower on the treated plants than on the control plants. In contrast, the number of lepidopteran larvae was not significantly different between the treated and control plants throughout the study period. Parasitized aphids (mummies) were also observed in both plots. Poisson regression analyses showed that a significantly higher number of mummies was recorded on the treated plants as compared to that on the control plants when the number of aphids increased. This suggested that PDJ application to Japanese radish plants attracted more parasitoid wasps on the treated plants than on the control plants. We also identified eight terpenoids and methyl salicylate as the PDJ-induced plant volatiles in the headspace of the treated plants. Some of these volatiles might be responsible for attracting aphid-parasitoid wasps in the field. However, for other insect pests, we did not find any natural enemies. Interestingly, the genes of the JA and salicylic acid signaling pathways were differentially upregulated in the treated plants. We also observed that the PDJ treatments induced the expression of the genes related to glucosinolate biosynthesis and the subsequent isothiocyanate formation. Additionally, the weights of both the aboveground and belowground parts of the treated plants were significantly lower than those of the respective parts of the control plants. These results indicated that the treatment of Japanese radish plants with a 100 times-diluted commercial formulation of PDJ induced their direct and indirect defenses against several insect pest species to reduce their numbers, and negatively affected their biomass.

Enhanced inflammatory responses have been suggested decades after radiation exposure in atomic-bomb survivors, but cellular and molecular alterations related to prolonged inflammation remain unclear. This study, utilizing longitudinal haematological data over 50 years for 14 000 persons, investigated whether radiation exposure promoted the relative increase in peripheral myeloid cells, known as an aging-associated indicator of low-grade inflammation. Statistical modelling was performed with a linear mixed-effects model for leucocyte subsets, together with a proportional hazards regression model for all-cause mortality. We found that age trends in lymphocyte, neutrophil and monocyte percentages or counts differed before versus after age 60 years. Radiation dose was associated with monocyte percentages and counts, but not with the lymphoid-myeloid cell ratio. Radiation effects on monocytes were stronger after versus before age 60 years. Increases in monocyte percentages and counts were associated with higher risk of all-cause mortality. Studies of chromosomal aberrations have shown a clonal expansion of haematopoietic stem cells among atomic-bomb survivors. Therefore, radiation exposure might accelerate aging-associated clonal haematopoiesis, which could result in a long-lasting elevation of circulating monocytes.

Although reactive oxygen species (ROS) play important roles in immune responses, excessive ROS production and accumulation might enhance the risk of inflammation-related diseases. Moreover, impaired immune function and the acceleration of pre-clinically persistent inflammation due to aging and radiation exposure have been observed in atomic bomb (A-bomb) survivors more than 60 years post-exposure. Meanwhile, the effects of aging and radiation exposure on ROS production in immune cells have not been characterized. This study investigated the relationship between intracellular ROS (H2O2 and O2•-) levels in blood cells or T cell subsets and serum iron, ferritin, and C-reactive protein (CRP) levels, as well as how these variables are affected by age and radiation exposure in A-bomb survivors. We examined 2495 Hiroshima A-bomb survivors. Multiple linear regression models adjusted for confounding factors indicated that intracellular O2•- levels in monocytes, granulocytes, and lymphocytes, and particularly in memory CD8+ T cells, including effector memory and terminally differentiated effector memory CD8+ T cells, increased with radiation dose. Additionally, serum iron, ferritin, and CRP levels affected intracellular ROS levels in specific blood cell types and T cell subsets. Serum CRP levels increased significantly with increasing age and radiation dose. Finally, when divided into three groups according to serum CRP levels, dose-dependent increases in the intracellular O2•- levels in blood cells and central memory and effector memory CD8+ T cells were most prominently observed in the high-CRP group. These results suggest that an increase in the levels of certain intracellular ROS, particularly after radiation exposure, might be linked to enhanced inflammatory status, including elevated serum CRP levels and reduced serum iron levels. This study reveals that aging and radiation exposure increase oxidative stress in blood cells, which is involved in impaired immune function and accelerated pre-clinically persistent inflammation in radiation-exposed individuals.

The objective of this study was to evaluate effects of whole body radiation exposure early in life on influenza vaccination immune responses much later in life. A total of 292 volunteers recruited from the cohort members of ongoing Adult Health Study (AHS) of Japanese atomic bomb (A-bomb) survivors completed this observational study spanning two influenza seasons (2011-2012 and 2012-2013). Peripheral blood samples were collected prior to and three weeks after vaccination. Serum hemagglutination inhibition (HAI) antibody titers were measured as well as concentrations of 25 cytokines and chemokines in culture supernatant from peripheral blood mononuclear cells, with and without in vitro stimulation with influenza vaccine. We found that influenza vaccination modestly enhanced serum HAI titers in this unique cohort of elderly subjects, with seroprotection ranging from 18 to 48% for specific antigen/season combinations. Twelve percent of subjects were seroprotected against all three vaccine antigens post-vaccination. Males were generally more likely to be seroprotected for one or more antigens post-vaccination, with no differences in vaccine responses based on age at vaccination or radiation exposure in early life. These results show that early life exposure to ionizing radiation does not prevent responses of elderly A-bomb survivors to seasonal influenza vaccine.

The elastoplastic deformation behaviors of thin-walled tubes made of pure aluminum and steel were measured under various tension–torsion combined loadings. The ratio between the displacement and rotation of a grip was held constant for the linear-loading experiment. In the nonlinear-loading experiments, a specimen was subjected to uniaxial tension followed by the simultaneous application of tension and torsion. It was determined that the associated flow rule predicts the plastic flow behaviors observed in the experiments with sufficient accuracy, provided that the specimen was subjected to linear loadings. Meanwhile, under nonlinear loadings, the plastic flow behaviors were markedly dissimilar to those in the linear loadings, and the direction of plastic flow rotated toward the direction of the stress/strain rate. By analyzing the experimental results, a linear relationship between the plastic flow direction and strain rate direction was determined. Therefore, the experimental data demonstrated that the stress state and the strain rate direction are essential parameters characterizing a plastic flow rule. Eventually, a pseudo-corner model capable of reproducing experimentally observed plastic deformation behavior was proposed.

Elastoplastic responses of rate-independent polycrystals are simulated under linear and various nonlinear strain paths, and the influence of the loading condition on the plastic flow behavior is investigated. It is observed that the shear components of elastoplastic tangent moduli start decreasing when the plastic deformation occurs, and the direction of the plastic flow depends on the direction of the stress/strain rates. A phenomenological plastic flow rule capable of reproducing these behaviors is developed. The flow rule relates the direction of plastic strain rate to the direction of strain rate, and yields the reduction of shear modulus after plastic yielding. The proposed constitutive model is then integrated into a finite element program, and the plane strain tension and pure bending are analyzed. The advantage of the proposed flow rule for simulating the occurrence of a shear band is demonstrated.

This study is mainly concerned with the potential hazards of interactive friction force on a human–robot contact surface, which may result in various skin traumas, such as friction blisters. In thi...

A series of benzothieno[3,2-b]benzoheteroles containing Group 15 (N, P, As, and Sb) and Group 16 (O, S, Se, and Te) elements were synthesized by a versatile method. X-ray analyses revealed that all the tetracyclic heteroacene skeletons were planar. A linear relationship was found between the excitation energies of Group 16-heteroacenes and their atomic radius, in contrast to Group 15-heteroacenes. Density functional theory calculations and electrochemical measurements were performed to understand the structure–optical property relationship.

This research is a proposal of a novel transfer device using a Transverse Flux-Flux Reversal Linear Motor (TF-FRLM). Transfer device in this paper is mounted on a carrier apparatus which was operated in parallel synchronous operation. This digest mainly discusses the overview of a novel transfer device and the optimization result of C-core TF-FRLM. The section of new transfer device describes the basic structure and basic operation. In the section on optimization, the results of dimensional change are shown on the graph and the optimum points are discussed. Three-dimensional finite element analysis is used for dimension optimization.

The formability of AZ31 sheets was experimentally measured for uniaxial tension, plane strain stretching, and equi-biaxial stretching modes. The limit strain of the specimen was reasonable under uniaxial tension but was drastically reduced in the biaxial stretching modes. Full-field strain analysis and the observation of the fracture surface revealed that the specimen fractured without the formation of a visible local necking. To predict the fracture behavior using a crystal plasticity-based finite element method, a mean field model was developed to solve the mechanical interplay between the parent and twins. The destabilization of the specimen was simulated by introducing fracture criteria as functions of the accumulated slip inside the contraction twin region. Simulations revealed that strong strain heterogeneity forms in the case of the biaxial stretching modes, and this heterogeneity is apparently reduced under uniaxial tension as a result of the activation of prismatic slip, which produces a uniform strain distribution. Contraction twins nucleate at smaller strain levels in the biaxial stretching modes, and premature failure is predicted in the biaxial stretching modes as a result of the accumulation of slip in the twinned regions. Parametric studies show that even when the volume fraction of twins is small, they have a significant impact on the ductility of AZ31 sheets.

Plastic flow rule is a fundamental equation that describes the plastic behavior of polycrystalline aggregate. To clarify plastic response at the point where the loading mode is suddenly changed, uniaxial tension followed by combined tension–torsion was applied to an A3003-O tube. The loading mode was altered at different plastic strains. It was observed that the direction of the plastic strain rate rotated immediately when the loading mode was changed. The greater the deviation in the subsequent loading mode from the uniaxial tension, the higher is the extent of rotation of the direction of plastic strain rate. The extent of instantaneous rotation of the plastic flow direction was the same regardless of the magnitude of the plastic strain at the alteration of the loading mode. Thus, the experimental results showed that the direction of the plastic flow depended on the direction of the stress/strain rate tensor; however, it was not affected by the magnitude of the plastic strain. Then, the effects of the hardening behavior of a slip system on the direction of the plastic flow were examined through a crystal plasticity simulation that considers the latent and kinematic hardenings. The crystal plasticity simulations reproduced the experimentally observed rotation of the plastic flow direction. Moreover, the simulations showed that the latent and kinematic hardenings did not affect the direction of the macroscopic plastic flow, even though they altered the activities of the slip systems. Therefore, it became clear that the plastic flow behavior of the polycrystal depends on the stress state and the direction of the stress/strain rate, and it is not affected by either the magnitude of the plastic strain or the hardening behavior of a slip system.

Previous immunological studies in atomic bomb survivors have suggested that radiation exposure leads to long-lasting changes, similar to immunological aging observed in T-cell-adaptive immunity. However, to our knowledge, late effects of radiation on dendritic cells (DCs), the key coordinators for activation and differentiation of T cells, have not yet been investigated in humans. In the current study, we hypothesized that numerical and functional decreases would be observed in relationship to radiation dose in circulating conventional DCs (cDCs) and plasmacytoid DCs (pDCs) among 229 Japanese A-bomb survivors. Overall, the evidence did not support this hypothesis, with no overall changes in DCs or functional changes observed with radiation dose. Multivariable regression analysis for radiation dose, age and gender effects revealed that total DC counts as well as subpopulation counts decreased in relationship to increasing age. Further analyses revealed that in women, absolute numbers of pDCs showed significant decreases with radiation dose. A hierarchical clustering analysis of gene expression profiles in DCs after Toll-like receptor stimulation in vitro identified two clusters of participants that differed in age-associated expression levels of genes involved in antigen presentation and cytokine/chemokine production in cDCs. These results suggest that DC counts decrease and expression levels of gene clusters change with age. More than 60 years after radiation exposure, we also observed changes in pDC counts associated with radiation, but only among women.

The role of Notch signaling in human innate lymphoid cell (ILC) differentiation is unclear, although IL-7 and IL-15 promote differentiation of natural cytotoxicity receptor (NCR) NKp44+ group 3 ILCs (NCR+ILC3s) and conventional NK (cNK) cells from CD34+ hematopoietic progenitor cells (HPCs) ex vivo. In this study, we analyzed the functions of Notch in the differentiation of NCR+ILC3s and cNK cells from human HPC subpopulations circulating in peripheral blood by limiting dilution and clonal assays using high-throughput flow cytometry. We demonstrated that Notch signaling in combination with IL-7 induced NCR+ILC3 differentiation, but conversely suppressed IL-15–dependent cNK cell generation in CD45RA+Flt-3−c-Kitlow, a novel innate lymphocyte-committed HPC subpopulation. In contrast, Notch signaling induced CD45RA−Flt-3+c-Kithigh multipotent HPCs to generate CD34+CD7+CD62Lhigh, the earliest thymic progenitor–like cells, which preserved high cNK/T cell potential, but lost NCR+ILC3 potential. These findings implicate the countervailing functions of Notch signaling in the fate decision between NCR+ILC3 and cNK cell lineages at different maturational stages of human HPCs. Inhibition of Notch functions by Abs specific for either the Notch1 or Notch2 negative regulatory region suggested that both Notch1 and Notch2 signals were involved in the fate decision of innate lymphocyte-committed HPCs and in the generation of earliest thymic progenitor–like cells from multipotent HPCs. Furthermore, the synergistic interaction between Notch and IL-7 in NCR+ILC3 commitment was primarily explicable by the induction of IL-7 receptor expression in the innate lymphocyte–committed HPCs by Notch stimulation, suggesting the pivotal role of Notch in the transcriptional control required for human NCR+ILC3 commitment.

Background: In soccer performance, coordination training is important and there is a high chance of injury due to improper concentration during a performance, but there is little research on the relationship with injury. The aim of this study was to assess the effect of dual-task training on young soccer players' attention distribution ability, physical function and performance, and occurrence of injury. Methods: The subjects were 70 soccer players as intervention group and 52 players were as control group (age of all subjects was 15.9 ± 0.8 years, the height was 168.8 ± 5.3 cm, and the body weight was 59.5 ± 6.2 kg). Agility t-test and an original dual-task agility t-test were measured as indicator of attention distribution ability. The history of subjects’ injuries was interviewed, and a single-leg triple hop for the distance test and a single-leg standing test with closed eyes were measured as physical function. The dual-task training concluded 5 items and the intervention was performed in approximately 20 minutes one time and six times over 3 weeks at a frequency of twice weekly. The number of people with injuries in each group and each measurement value was compared in each group. Results: The control group comprised 10 subjects with injuries before intervention and 7 after intervention, whereas the intervention group comprised 12 subjects with injuries before intervention and 3 after intervention. No significant differences were observed in any of the parameters after the intervention in either of the two groups. Conclusion: Whether this difference was caused by the intervention remains unclear; however, it is possible that the training program in this study was effective for short-term injury prevention. The contents of evaluation and training menu should be reexamined in the future.

Recent deep sequencing studies on T-cell receptor (TCR) repertoire have provided robust data to characterize diversity of T-cell immune responsiveness to a wide variety of peptide antigens, including viral and tumor antigens. The human TCR repertoire declines with age, but this decline has not been fully investigated longitudinally in individuals. Using a deep sequencing approach, we analyzed TCRβ repertoires longitudinally over approximately 20years, with ages ranging from 23 to 50years at the start (23 to 65years overall), in peripheral-blood CD4 and CD8 T-cell populations that were collected and cryopreserved 3 times at intervals of approximately 10years from each of 6 healthy adults (3 men and 3 women). Sequence data at the hypervariable complementarity determining region 3 (CDR3) in the TCRB gene locus were evaluated by applying a random-coefficient statistical regression model. Two outcomes were analyzed: total number of distinct TCRB CDR3 sequences as a TCR diversity metric, and clonality of the T-cell populations. TCR repertoire diversity decreased (p

Experimental and spectroscopic studies revealed unprecedented reactivity of a “naked” lithium cation with very weakly coordinating anions, including carborane anions. The superactivated lithium cation has greatly enhanced Lewis acidic character and mediates various organic reactions such as carbonyl-ene reaction, NBS-bromination of unactivated aromatics, and Friedel–Crafts alkylation, which are not promoted by conventional lithium salts. Chemical robustness of the counteranion also plays an important role in the chemistry of the strongly activated lithium cation.

In a series of studies of atomic bomb survivors, radiation-dose-dependent alterations in peripheral T-cell populations have been reported. For example, reduced size in naïve T-cell pools and impaired proliferation ability of T cells were observed. Because these alterations are also generally observed with human aging, we hypothesized that radiation exposure may accelerate the aging process of the T-cell immune system. To further test this hypothesis, we conducted cross-sectional analyses of telomere length, a hallmark of cellular aging, of naïve and memory CD4 T cells and total CD8 T cells in the peripheral blood of 620 atomic bomb survivors as it relates to age and radiation dose, using fluorescence in situ hybridization with flow cytometry. Since telomere shortening has been recently demonstrated in obesity-related metabolic abnormalities and diseases, the modifying effects of metabolic status were also examined. Our results indicated nonlinear relationships between T-cell telomere length and prior radiation exposure, i.e., longer telomeres with lower dose exposure and a decreasing trend of telomere length with individuals exposed to doses higher than 0.5 Gy. There were associations between shorter T-cell telomeres and higher hemoglobin Alc levels or fatty liver development. In naïve and memory CD4 T cells, radiation dose and high-density lipoprotein (HDL) cholesterol were found to positively interact with telomere length, suggesting that the decreasing trend of telomere length from a higher radiation dose was less conspicuous in individuals with a higher HDL cholesterol. It is therefore likely that radiation exposure perturbs T-cell homeostasis involving telomere length maintenance by multiple biological mechanisms, depending on dose, and that long-term-radiation-induced effects on the maintenance of T-cell telomeres may be modified by the subsequent metabolic conditions of individuals.

Physical stress hazards are identified as a part of the safety requirements for personal care robots as described in ISO 13482. We conducted a safety verification study to clarify an inherently safe condition region in the shear stress—time relationship: The higher the shear stress is, the smaller number of times is needed for blister generation. For validating the verified safety data, we also built a testbed where a manipulator is used to optimally control the position and force of a cuff in contact with a piece of porcine skin for the purpose of reproducing the contact conditions as close as possible to those obtained when a human wears a robot.

Immune system impairments reflected by the composition and function of circulating lymphocytes are still observed in atomic bomb survivors, and metabolic abnormalities including altered blood triglyceride and cholesterol levels have also been detected in such survivors. Based on closely related features of immune and metabolic profiles of individuals, we investigated the hypothesis that long-term effects of radiation exposure on lymphocyte subsets might be modified by metabolic profiles in 3,113 atomic bomb survivors who participated in health examinations at the Radiation Effect Research Foundation, Hiroshima and Nagasaki, in 2000-2002. The lymphocyte subsets analyzed involved T-, B- and NK-cell subsets, and their percentages in the lymphocyte fraction were assessed using flow cytometry. Health examinations included metabolic indicators, body mass index, serum levels of total cholesterol, high-density lipoprotein cholesterol, C-reactive protein and hemoglobin A1c, as well as diabetes and fatty liver diagnoses. Standard regression analyses indicated that several metabolic indicators of obesity/related disease, particularly high-density lipoprotein cholesterol levels, were positively associated with type-1 helper T- and B-cell percentages but were inversely associated with naive CD4 T and NK cells. A regression analysis adjusted for high-density lipoprotein cholesterol revealed a radiation dose relationship with increasing NK-cell percentage. Additionally, an interaction effect was suggested between radiation dose and C-reactive protein on B-cell percentage with a negative coefficient of the interaction term. Collectively, these findings suggest that radiation exposure and subsequent metabolic profile changes, potentially in relationship to obesity-related inflammation, lead to such long-term alterations in lymphocyte subset composition. Because this study is based on cross-sectional and exploratory analyses, the implications regarding radiation exposure, metabolic profiles and circulating lymphocytes warrant future longitudinal and molecular mechanistic studies.

Deprotonative directed ortho cupration of aromatic/heteroaromatic C–H bond and subsequent oxidation with t-BuOOH furnished functionalized phenols in high yields with high regio- and chemoselectivity. DFT calculations revealed that this hydroxylation reaction proceeds via a copper (I → III → I) redox mechanism. Application of this reaction to aromatic C–H amination using BnONH2 efficiently afforded the corresponding primary anilines. These reactions show broad scope and good functional group compatibility. Catalytic versions of these transformations are also demonstrated.

Accumulated DNA damage in hematopoietic stem cells is a primary mechanism of aging-associated dysfunction in human hematopoiesis. About 70 years ago, atomic-bomb (A-bomb) radiation induced DNA damage and functional decreases in the hematopoietic system of A-bomb survivors in a radiation dose-dependent manner. The peripheral blood cell populations then recovered to a normal range, but accompanying cells derived from hematopoietic stem cells still remain that bear molecular changes possibly caused by past radiation exposure and aging. In the present study, we evaluated radiation-related changes in the frequency of phosphorylated (Ser-139) H2AX (γH2AX) foci formation in circulating CD34-positive/lineage marker-negative (CD34 + Lin−) hematopoietic stem and progenitor cells (HSPCs) among 226Hiroshima A-bomb survivors. An association between the frequency of γH2AX foci formation in HSPCs and the radiation dose was observed, but the γH2AX foci frequency was not significantly elevated by past radiation. We found a negative correlation between the frequency of γH2AX foci formation and the length of granulocyte telomeres. A negative interaction effect between the radiation dose and the frequency of γH2AX foci was suggested in a proportion of a subset of HSPCs as assessed by the cobblestone area-forming cell assay (CAFC), indicating that the self-renewability of HSPCs may decrease in survivors who were exposed to a higher radiation dose and who had more DNA damage in their HSPCs. Thus, although many years after radiation exposure and with advancing age, the effect of DNA damage on the self-renewability of HSPCs may be modified by A-bomb radiation exposure.

Ionizing radiation (IR) is a major source of cellular damage and the immediate cellular response to IR has been well characterized. But the long-term impact of IR on cell function and its relationship with aging are not known. Here, we examined the IR effects on telomere length and other biomarkers 50 to 68 years post-exposure (two time points per person) in survivors of the atomic bombing at Hiroshima during WWII. We found that telomere length of leukocytes was inversely correlated with the dose of IR (p=0.008), and this effect was primarily found in survivors who were exposed at younger ages; specifically those

It is not yet known whether hematopoietic stem and progenitor cells (HSPCs) are compromised in the aging population of atomic bomb (A-bomb) survivors after their exposure nearly 70 years ago. To address this, we evaluated age- and radiation-related changes in different subtypes of circulating HSPCs among the CD34-positive/lineage marker-negative (CD34(+)Lin(-)) cell population in 231 Hiroshima A-bomb survivors. We enumerated functional HSPC subtypes, including: cobblestone area-forming cells; long-term culture-initiating cells; erythroid burst-forming units; granulocyte and macrophage colony-forming units; and T-cell and natural killer cell progenitors using cell culture. We obtained the count of each HSPC subtype per unit volume of blood and the proportion of each HSPC subtype in CD34(+)Lin(-) cells to represent the lineage commitment trend. Multivariate analyses, using sex, age and radiation dose as variables, showed significantly decreased counts with age in the total CD34(+)Lin(-) cell population and all HSPC subtypes. As for the proportion, only T-cell progenitors decreased significantly with age, suggesting that the commitment to the T-cell lineage in HSPCs continuously declines with age throughout the lifetime. However, neither the CD34(+)Lin(-) cell population, nor HSPC subtypes showed significant radiation-induced dose-dependent changes in counts or proportions. Moreover, the correlations of the proportions among HSPC subtypes in the survivors properly revealed the hierarchy of lineage commitments. Taken together, our findings suggest that many years after exposure to radiation and with advancing age, the number and function of HSPCs in living survivors as a whole may have recovered to normal levels.