Chalk River Laboratories

About: Chalk River Laboratories is a based out in . It is known for research contribution in the topics: Neutron diffraction & Neutron scattering. The organization has 2297 authors who have published 2700 publications receiving 73287 citations.

Interaction of Aspirin (Acetylsalicylic Acid) with Lipid Membranes

Abstract: We studied the interaction of Aspirin (acetylsalicylic acid) with lipid membranes using x-ray diffraction for bilayers containing up to 50 mol% of aspirin. From 2D x-ray intensity maps that cover large areas of reciprocal space we determined the position of the ASA molecules in the phospholipid bilayers and the molecular arrangement of the molecules in the plane of the membranes. We present direct experimental evidence that ASA molecules participate in saturated lipid bilayers of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) and preferably reside in the head group region of the membrane. Up to 50 mol% ASA molecules can be dissolved in this type of bilayer before the lateral membrane organization is disturbed and the membranes are found to form an ordered, 2D crystal-like structure. Furthermore, ASA and cholesterol were found to co-exist in saturated lipid bilayers, with the ASA molecules residing in the head group region and the cholesterol molecules participating in the hydrophobic membrane core.

Recovery of somatic embryos and plantlets from protoplast cultures of Larix × eurolepis

Abstract: Somatic embryos and plantlets were regenerated from protoplasts of hybrid larch (Larix × eurolepis) isolated from two embryogenic callus and cell suspension culture lines (L1 and L2). L2, which was highly embryogenic, consistently yielded protoplasts that gave rise to somatic embryos. Centrifugation on a discontinuous medium/Percoll density gradient resulted in accumulation of embryogenic protoplasts in one of the Percoll interfaces. First division frequencies were in the range of 28–39% in line 1 and 18–20% in line 2 in both liquid and agarose-solidified culture media. The critical factor in maintaining high viability of cultures was lowering of osmotic pressure by dilution of the initial medium. The first somatic embryos were detected in 23- to 28-day-old cultures. Some of these developed into plants that were transferred to soil.

Low Doses of Radiation Reduce Risk In Vivo

Abstract: The “Linear No Threshold” hypothesis, used in all radiation protection practices, assumes that all doses, no matter how low, increase the risk of cancer, birth defects and heritable mutations. In vitro cell based experiments show adaptive processes in response to low doses and dose rates of low LET radiation, and do not support the hypothesis. This talk will present cellular data and data from animal experiments that test the hypothesis in vivo for cancer risk. The data show that a single, low, whole body dose (less than about 100 mGy) of low LET radiation, given at low dose rate, increased cancer latency and consequently reduced both spontaneous and radiation-induced cancer risk in both genetically normal and cancer-prone mice. This adaptive response lasted for the entire lifespan of all the animals that developed these tumors, and effectively restored a portion of the life that would have been lost due to the cancer in the absence of the low dose. Overall, the results demonstrate that the assumption of a linear increase in risk with increasing dose in vivo is not warranted, and that low doses actually reduce risk.