We present a new approach to model dose rate effects on cell killing after photon radiation based on the spatio-temporal clustering of DNA double strand breaks (DSBs) within higher order chromatin structures of approximately 1-2 Mbp size, so called giant loops. The main concept of this approach consists of a distinction of two classes of lesions, isolated and clustered DSBs, characterized by th...

Although increased superoxide dismutase (SOD) activity is often associated with enhanced resistance of cells and organisms to oxidant challenges, few direct tests of the antioxidant importance of this enzyme have been carried out. To assess the importance of SOD in defending against gamma-radiation, we employed Escherichia coli with deficient, normal, and super-normal enzyme activities. Surpris...

DNA double-strand breaks are the critical lesions responsible for the majority of ionizing radiation-induced cell killing. Thus, the ability of tumor cells to elicit a DNA damage response following radiation, via activation of DNA repair and cell-cycle checkpoints, promotes radiation resistance and tumor cell survival. Consequently, agents that target these DNA damage response pathways are bein...

the effects of chronic administration of lithium, on acute toxicity of chlorpromazine (cpz) in male albino mice was studied and the ldso values were determined from dose-probit curves. tfie results showed that in lithium pretrealed animals (anmials consumed drinking water containing 600mg/l lithium chloride for 10 days) the ld50 value (the dose corresponding to probit 5) of cpz increased signif...

OBJECTIVE Suicide is a major public health concern. This study aimed to determine the predictors of repeated suicide attempts, focusing on whether lethality level of the suicidal method predicts the risk of subsequent suicide attempts. METHODS All consecutive individuals (N=2,070) with an episode of nonfatal self-harm registered in a surveillance database provided by the Department of Health ...

Mutations in Kirsten rat-sarcoma (KRAS) are well appreciated to be major drivers of human cancers through dysregulation of multiple growth and survival pathways. Similar to many other non-kinase oncogenes and tumor suppressors, efforts to directly target KRAS pharmaceutically have not yet materialized. As a result, there is broad interest in an alternative approach to develop therapies that ind...

Systemic administration of recombinant thrombomodulin (TM) confers radiation protection partly by accelerating hematopoietic recovery. The uniquely potent radioprotector gamma tocotrienol (GT3), in addition to being a strong antioxidant, inhibits the enzyme hydroxy-methyl-glutaryl-coenzyme A reductase (HMGCR) and thereby likely modulates the expression of TM. We hypothesized that the mechanism ...

Exposure of Venezuelan equine encephalomyelitis (VEE) virus (at -70 C) to 6 x 106 r y-radiation (6WCo) resulted in loss of lethality for young adult mice and guinea pigs, and loss of capacity to produce plaques or cyLopathic effects in tissue culture. The suckling mouse was more sensitive for detecting live virus in radiated suspensions than was the adult mouse or guinea pig. Live virus was dem...

Mutations occur at a higher rate in space than under terrestrial conditions, primarily due to an increase in radiation levels. These mutations may effect the productivity of plants found in a controlled ecological life support system (CELSS). Computer simulations of plants with different ploidies, modes of reproduction, lethality thresholds, viability thresholds and susceptibilities to radiatio...