Intercellular communication of DNA damage and oxidative status underpin bystander effects.

Purpose: A well-known phenomenon in the field of radiation biology is that cells exposed to ionizing radiation (IR) (targeted cells) can induce in non-irradiated (non-targeted), bystander cells effects reminiscent of DNA damage responses (DDR) normally expected, exclusively in targeted cells. These phenomena are collectively referred to as radiation-induced bystander effects (RIBE) and have different manifestations depending on the endpoint studied. Although it is now recognized that RIBE reflects to a considerable extent communication by the targeted cells to undamaged cells of their damaged status, the molecular underpinnings of this communication and its significance for the organism are only partly understood.

[Radiation protection in medical research : Licensing requirement for the use of radiation and advice for the application procedure].

Background: In Germany, persons who are to be exposed to radiation for medical research purposes are protected by a licensing requirement. However, there are considerable uncertainties on the part of the applicants as to whether licensing by the competent Federal Office for Radiation Protection is necessary, and regarding the choice of application procedure.

Aim: The article provides explanatory notes and practical assistance for applicants and an outlook on the forthcoming new regulations concerning the law on radiation protection of persons in the field of medical research.

Bystander effects as manifestation of intercellular communication of DNA damage and of the cellular oxidative status.

It is becoming increasingly clear that cells exposed to ionizing radiation (IR) and other genotoxic agents (targeted cells) can communicate their DNA damage response (DDR) status to cells that have not been directly irradiated (bystander cells). The term radiation-induced bystander effects (RIBE) describes facets of this phenomenon, but its molecular underpinnings are incompletely characterized. Consequences of DDR in bystander cells have been extensively studied and include transformation and mutation induction; micronuclei, chromosome aberration and sister chromatid exchange formation; as well as modulations in gene expression, proliferation and differentiation patterns.

The impact of serotonin on the development of bystander damage assessed by γ-H2AX foci analysis.

Purpose: This investigation addresses the question of whether serum constituents have a modulating effect on the induction of bystander effects. It was carried out as part of an inter-laboratory comparison-exercise within the European Union-integrated project NOTE (Non-targeted effects of ionizing radiation). Serotonin is a neurotransmitter, which is present in the circulatory system and therefore in blood serum.

Dependence of adaptive response and its bystander transmission on the genetic background of tested cells.

Purpose: Radiation-induced adaptive response (AR) is a phenomenon of increased radioresistance mediated by a low priming dose of ionizing radiation (IR) applied prior to a higher challenging dose. We have previously shown that in mouse-embryo fibroblasts (MEF) and human A549 cells, AR is associated with enhanced repair of DNA double-strand breaks (DSB) by the DNA-PK-dependent pathway of non-homologous end-joining (D-NHEJ). Importantly, AR was 'transmitted' to non-irradiated bystander cells through transfer of medium from cells that had received a priming dose of IR.