Radiation dose from high-energy nucleons in targets containing soft tissue and bone.
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Biomedical subjects
Publications and source records attributed to V E Anderson.
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A universal procedure to isolate cross-linked peptides has been demonstrated. The procedure relies on initially converting the epsilon-amino groups of lysine to dimethyl lysine by reductive methylation with sodium cyanoborohydride and formaldehyde. The lysine-modified protein is proteolytically cleaved and the resulting alpha-amino groups derivatized with methoxypoly(ethylene glycol)5000 succinyl hydroxysuccinimide. Any unintentional derivatization of tyrosine side chains can be reversed by incubation under mildly alkaline conditions. The cross-linked polypeptides contain two poly(ethylene glycol)5000 chains while non-cross-linked peptides contain a single poly(ethylene glycol)5000 chain. The two populations of peptides can be separated by gel filtration chromatography. This procedure has been shown capable of isolating cross-linked peptides using glutathione, lysozyme, chemically cross-linked hemoglobin, and neurofibrillary tangles isolated from the brain of a case of Alzheimer's disease.
Evidence of genetic factors in seizure disorders by examination of plasma amino acid concentrations in multiply affected sibships was investigated. The strategy of multiply affected sibship ascertainment was used to reduce heterogeneity as one of several potential sources of variation in quantitative amino acid levels. Our results do not support previously reported increases in plasma taurine, aspartic acid, or glutamic acid in seizure patients. However, we do find that multiply affected sibships have significantly elevated plasma concentrations of arginine and asparagine, and significantly decreased ornithine. These amino acid concentrations may be under quantitative genetic control. Within-sibship comparisons indicate that seizure patients have increased glutamine and decreased lysine and phenylalanine, possibly secondary to the seizures. We also find that anticonvulsant use complicates statistical analyses. Further studies to more clearly delineate the genetics of plasma amino acid concentrations (or other quantitative metabolic measures) and their role in seizure disorders are required and will benefit from the use of a homogeneous sampling strategy.