Biomedical subjects
Publications and source records attributed to R S Coleman.
We describe a solution to a molecular mechanics parameterization problem involving disulfide bonds between thionucleosides. Key torsional and bending parameters developed from ab initio calculations were incorporated into the AMBER* force-field in order to accurately represent the disulfide linkage in DNA cross-linked via this bond.
Full details of the template-directed covalent cross-linking of duplex oligodeoxynucleotides are presented. 4-Thio-2'-deoxyuridine was incorporated synthetically into a 17mer oligodeoxynucleotide, and the thiocarbonyl group of the modified base was alkylated with a variety of alpha-bromoacetyl-derivatized diamines. Covalent cross-linking was initiated by annealing the electrophilic probe oligomers with their complementary sequences, where a dG base was targeted at the position complementary to the modified 4-thio-2'-deoxyuridine. The sequence selectivity of cross-link formation as a function of tether topology and rigidity was examined, and the thermal stability of the modified duplexes was measured by UV melting experiments.
The comparative DNA binding properties and cytotoxic activity of CDPIn methyl esters (n = 1-5) vs. PDE-In methyl esters (n = 1-3) are detailed in studies which provide experimental evidence for the intrinsic importance of stabilizing hydrophobic binding and non-covalent van der Waals contacts dominant in the CC-1065/B-DNA minor groove binding. High affinity minor groove binding to DNA was established through: (1) the observation of CDPI3 binding (UV) but not unwinding of supercoiled DNA (phi 174 RFI DNA) thus excluding intercalative binding; (2) the observation of CDPI3 binding to T4 phage DNA (UV, delta Tm) in which the major groove is occluded by glycosylation thus excluding major groove binding; (3) the observation of salt (Na+) concentration independent high affinity CDPI3 binding to poly(dA . poly(dT) thus excluding simple electrostatic binding to the DNA phosphate backbone; and further inferred through (4) the observation of an intense induced dichroism (ICD, poly(dA) . poly(dT) and poly(dG) . poly(dC) [phi]23(358) = 24,000 and 23,500). This high affinity minor groove binding is sufficient to produce a potent cytotoxic effect.(ABSTRACT TRUNCATED AT 400 WORDS)
As shared governance increases in organizations that employ nurses, it becomes an essential element of professional socialization and preservice education. Framing a course in concepts of shared governance offers students experiential learning in uses of power, accountability, organizational decision making, and peer negotiation. The authors present concepts and examples of classroom shared governance from student and teacher perspectives.