Extragalactic HII regions and their ionizing star clusters are the most prominent signposts of recent starbirth activity in galaxies. In this paper, we present optical measurements of nearby extragalactic HII regions with the aim of investigating possible relationships between the newborn ionizing clusters and their dynamical environment. Evidence for variations in the measured HII region prope...

We discuss recent results on the ionizing fluxes of O stars obtained from our “combined stellar structure and atmosphere models” (CoStar) accounting for stellar winds, non-LTE effects and line blanketing. The implications on the ionization structure of H ii regions are summarized, and observational constraints on the ionizing spectra and the total ionizing photon fluxes are presented. Using our...

Introduction: Retinoblastoma (RB) is a malignant retinal tumor, which affects infants and children. This cancer happens through a mutation in the retinoblastoma tumor suppressor genes (RB1). Inactivation of RB1 has been observed in more than 97% of all retinoblastoma patients with mutations. In recent years, RB treatment has developed significantly. RBchr('39')s treatment methods can be one or ...

BACKGROUND Melanin pigments are ubiquitous in nature. Melanized microorganisms are often the dominating species in certain extreme environments, such as soils contaminated with radionuclides, suggesting that the presence of melanin is beneficial in their life cycle. We hypothesized that ionizing radiation could change the electronic properties of melanin and might enhance the growth of melanize...

Cells exposed to densely ionizing radiation (high-LET) experience more severe biological damage than do cells exposed to sparsely ionizing radiation (low-LET). The prevailing hypothesis is that high-LET radiations induce DNA double strand-breaks (DSB) that are more complex and clustered, and are thereby more challenging to repair. Here, we present experimental data obtained by atomic force micr...

Evidence of health benefits and longer average life-span following low-dose irradiation should replace fear, “all radiation is harmful,” and “the perception of harm” as the basis for action in the 21 century. Hormesis is the excitation, or stimulation, by small doses of any agent in any system. Large doses inhibit. “Low dose” is defined as any dose between ambient levels of radiation and the th...

Although several signaling pathways have been suggested to be involved in the cellular response to ionizing radiation, the molecular basis of tumor resistance to radiation remains elusive. We have developed a unique model system based upon the MCF-7 human breast cancer cell line that became resistant to radiation treatment (MCF+FIR30) after exposure to chronic ionizing radiation. By proteomics ...

Macroautophagy (mAG) is a lysosomal mechanism of degradation of cell self-constituents damaged due to variety of stress factors, including ionizing irradiation. Activation of mAG requires expression of mAG protein Atg8 (LC3) and conversion of its form I (LC3-I) to form II (LC3-II), mediated by redox-sensitive Atg4 protease. We have demonstrated upregulation of this pathway in the innate host de...