Potential of Macrostomum lignano to recover from γ-ray irradiation

Stem cells are the only proliferating cells in flatworms and can be eliminated by irradiation with no damage to differentiated cells. We investigated the effect of fractionated irradiation schemes on Macrostomum lignano, namely, on survival, gene expression, morphology and regeneration. Proliferating cells were almost undetectable during the first week post-treatment. Cell proliferation and gene expression were restored within 1 month in a dose-dependent manner following exposure to up to 150 Gy irradiation. During recovery, stem cells did not cross the midline but were restricted within lateral compartments. An accumulated dose of 210 Gy resulted in a lethal phenotype. Our findings demonstrate that M. lignano represents a suitable model system for elucidating the effect of irradiation on the stem cell system in flatworms and for improving our understanding of the recovery potential of severely damaged stem-cell systems

Is genetic counseling a stressful event?

Purpose. The aim of this paper was to investigate whether cancer genetic counseling could be considered as a stressful event and associated with more anxiety and/or depression compared to other cancer-related events for instance attending mammography screening or receiving a cancer diagnosis. Methods. A total of 4911 individuals from three Scandinavian countries were included in the study. Data was collected from individuals who had attended either cancer genetic counseling (self-referred and physician-referred) or routine mammography screening, were recalled for a second mammograpy due to a suspicious mammogram, had received a cancer diagnosis or had received medical follow-up after a breast cancer-surgery. Data from the genetic counseling group was also compared to normative data. Participants filled in the Hospital Anxiety and Depression Scale twice: prior to a potentially stressful event and 14 days after the event. Results. Pre-counseling cancer genetic counselees reported significant lower level of anxiety compared to the cancer-related group, but higher levels of anxiety compared to the general population. Furthermore, the level of depression observed within the genetic counseling group was lower compared to other participants. Post-event there was no significant difference in anxiety levels between the cancer genetic counselees and all other groups; however, the level of depression reported in the self-referred group was significantly lower than observed in all other groups. Notably, the level of anxiety and depression had decreased significantly from pre-to post-events within the genetic counseling group. In the cancer-related group only the level of anxiety had decreased significantly post-event. Conclusion. Individuals who attend cancer genetic counseling do not suffer more anxiety or depression compared to all other cancer-related groups. However, some counselees might need additional sessions and extended support. Thus, identifying extremely worried individuals who need more support, and allocating further resources to their care, seems to be more sufficient

Fluoride inhibits the response of bone cells to mechanical loading

The response of bone cells to mechanical loading is mediated by the cytoskeleton. Since the bone anabolic agent fluoride disrupts the cytoskeleton, we investigated whether fluoride affects the response of bone cells to mechanical loading, and whether this is cytoskeleton mediated. The mechano-response of osteoblasts was assessed in vitro by measuring pulsating fluid flow-induced nitric oxide (NO) production. Osteocyte shape was determined in hamster mandibles in vivo as parameter of osteocyte mechanosensitivity. Pulsating fluid flow (0.7 ± 0.3 Pa, 5 Hz) stimulated NO production by 8-fold within 5 min. NaF (10-50 μM) inhibited pulsating fluid flow-stimulated NO production after 10 min, and decreased F-actin content by ~3-fold. Fluid flow-induced NO response was also inhibited after F-actin disruption by cytochalasin B. NaF treatment resulted in more elongated, smaller osteocytes in interdental bone in vivo. Our results suggest that fluoride inhibits the mechano-response of bone cells, which might occur via cytoskeletal changes. Since decreased mechanosensitivity reduces bone mass, the reported anabolic effect of fluoride on bone mass in vivo is likely mediated by other factors than changed bone cell mechanosensitivity. © 2011 The Society of The Nippon Dental University