Three-dimensional visualization of neural networks inside bone by Osteo-DISCO protocol and alteration of bone remodeling by surgical nerve ablation.

Bone is one of the largest organ systems in humans and is considered to regulate whole-body homeostasis in cooperation with other organs. We have previously reported that a sympathetic or sensory nervous system inside bone regulates bone homeostasis. However, the detailed regulatory mechanism, including the distribution of nerves inside bone, remains unknown. Although a two-dimensional histological analysis has been widely used to evaluate the structure of nerves or blood vessels, the actual structure is more complex, suggesting that it should be evaluated three-dimensionally. Here, we established a novel bone tissue clearing technique (Osteo-DISCO) for murine bones which enabled us to visualize the detailed distribution of nerves or blood vessels inside bone. Interestingly, we found that there is a specific nerve entry site in each long bone and that surgical ablation of the specific nerve fibers entering bone tissue led to decreased bone formation and impaired bone regeneration. Furthermore, we revealed that the administration of calcitonin gene-related peptide (CGRP), which is primarily released from sensory nerves, suppressed the bone loss caused by surgical nerve ablation. An in vitro study also indicated that CGRP directly promotes osteoblast activity, suggesting that sensory nerves inside bone can regulate osteogenesis via the secretion of CGRP.

[Approach to easing occupational stress for high-stress workers: applying the brief job stress questionnaire to workplace mental health promotion].

We investigated job stress among 442 employees from 19 divisions in a Japanese company using the Brief Job Stress Questionnaire. Job stress of the employees was estimated by the score for total health risk. Among the 19 divisions, two divisions showed over 120 points of mean total health risk score. Intervention with a stress-reduction program was carried out in these 2 divisions. First, to assess the job stress, health care staff interviewed all workers in the 2 divisions. Second, the results of the interviews were reported to the divisions' managers. Third, the managers applied the best remedy for job stress in their workplaces. In addition, occupational health staff conducted mental health education as well as individual interviews for the workers from the 2 divisions. At reevaluation one year later, both divisions showed a decreased general health risk (under 120 points). No sick leaves for depression occurred within the 2 divisions during the intervention. The results of the present study suggest that the intervention was effective in easing occupational stress for high-stress workers. The stress reduction program also seemed to have helped managers to change their recognition of occupational mental health and enabled close cooperation with occupational health staff, which may improve mental health in the workplace.

The in vivo Pig-a gene mutation assay is useful for evaluating the genotoxicity of ionizing radiation in mice.

The in vivo Pig-a mutation assay has been adapted for measuring mutation in rats, mice, monkeys, and humans. To date, the assay has been used mainly to assess the mutagenicity of chemicals that are known to be powerful point mutagens. The assay has not been used to measure the biological effects associated with ionizing radiation. In this study, we modified the Pig-a gene mutation assay (Kimoto et al. [2011b]: Mutat Res 723:36-42) and used 3-color staining with fluorescently labeled anti-CD24, anti-TER-119, and anti-CD71 to detect the Pig-a mutant frequencies in total red blood cells (RBCs) and in reticulocytes (RETs) from X-irradiated mice. Single exposures to X-irradiation resulted in dose- and time-dependent increases in Pig-a mutant frequencies, and these subsequently declined over time returning to background frequencies. The same total amount of radiation, delivered either as a single dose or as four repeat doses at weekly intervals, increased Pig-a mutant frequencies to comparable levels, reaching maxima 2-3 weeks after the single dose or 2-3 weeks after the last of the repeat doses. These increased frequencies subsequently returned to background levels. Our results indicated that the 3-color Pig-a assay was useful for evaluating the in vivo genotoxicity of radiation.