Kathryn D Held

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Ionising radiation has been an important part of cancer treatment for almost a century, being used in external-beam radiotherapy, brachytherapy, and targeted radionuclide therapy. At the molecular and cellular level, cell killing has been attributed to deposition of energy from the radiation in the DNA within the nucleus, with production of DNA(More)
Although radiation-induced bystander effects have been demonstrated in a number of cell types, the studies have largely been performed using high linear energy transfer (LET) radiation, such as alpha-particles. The literature is contradictory on whether fibroblasts show bystander responses, especially after low LET radiation such as X- or gamma-rays and(More)
The Gray Cancer Institute ultrasoft X-ray microprobe was used to quantify the bystander response of individual V79 cells exposed to a focused carbon K-shell (278 eV) X-ray beam. The ultrasoft X-ray microprobe is designed to precisely assess the biological response of individual cells irradiated in vitro with a very fine beam of low-energy photons.(More)
In space, astronauts are exposed to radiation fields consisting of energetic protons and high atomic number, high-energy (HZE) particles at very low dose rates or fluences. Under these conditions, it is likely that, in addition to cells in an astronaut's body being traversed by ionizing radiation particles, unirradiated cells can also receive intercellular(More)
Previous studies have shown that under certain conditions some thiol-containing compounds can cause apoptosis in a number of different cell lines. Herein, we investigated the apoptotic pathways in HL-60 cells triggered by dithiothreitol (DTT), used as a model thiol compound, and tested the hypothesis that thiols cause apoptosis via production of hydrogen(More)
Although bystander effects have been shown for some high-LET radiations, few studies have been done on bystander effects induced by heavy-ion radiation. In this study, using a Transwell insert co-culture system, we have demonstrated that irradiation with 1 GeV/nucleon iron ions can induce medium-mediated bystander effects in normal AG01522 human(More)
mTOR is a highly conserved serine/threonine protein kinase that serves as a central regulator of cell growth, survival, and autophagy. Deregulation of the PI3K/Akt/mTOR signaling pathway occurs commonly in cancer and numerous inhibitors targeting the ATP-binding site of these kinases are currently undergoing clinical evaluation. Here, we report the(More)
PURPOSE In space, astronauts are exposed to mixed radiation fields consisting of energetic protons and high atomic number, high energy (HZE) particles at low dose rates. Therefore, it is critical to understand effects of combinations of low doses of different radiation types at the cellular level. MATERIALS AND METHODS AG01522 normal human skin(More)
We have established controlled conditions for studying the reaction of chemically and radiolytically produced hydroxyl radical (.OH) with 2-deoxy-D-ribose (2-DR). Ascorbate (ASC) or dithiothreitol (DTT) and cuprous or cupric ions were used to generate the OH-radical. The OH-radical was detected using the classical method of measuring the amount of(More)
When Chinese hamster V79 cells are exposed to various thiol compounds in phosphate-buffered saline (PBS), some compounds cause toxicity (loss of colony formation), although the dependence on drug concentration and the magnitude of the cell killing vary between the different thiols. For example: dithiothreitol (DTT) and WR-1065 cause a biphasic toxicity(More)