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Biomedical subjects

D C Ward

Publications and source records attributed to D C Ward.

259 records · Page 15Linked to original sources
PubMed1969

Stereochemical analysis of the specificity of pancreatic RNAse with polyformycin as substrate: differentiation of the transphosphorylation and hydrolysis reactions.

A stereochemical analysis of the substrate and inhibitor specificities of bovine pancreatic ribonuclease A is presented. A scheme is proposed in which the binding specificity for this protein-nucleic acid interaction is rationalized in terms of a simple system of H-bonds. The functional groups that govern substrate binding for transphosphorylation and hydrolysis, respectively, are considered and differentiated, and predictions are offered concerning the interaction of presumptive substrates with RNase.

Animals↗
PubMed1965

Base specificity in the interaction of polynucleotides with antibiotic drugs.

Echinomycin, daunomycin, ethidium bromide, nogalamycin, chromomycin, mithramycin, and olivomycin inhibit RNA synthesis by RNA polymerase by interacting with the DNA template. Chromomycin and olivomycin form complexes with DNA, preferably in the helical form, but not with RNA. These complexes require guanine in DNA and the addition of a stoichiometric amount of bivalent cation. None of the other antibiotics requires the presence of any single base in the template for its action.

Animals↗
PubMedDate not supplied

Internet-based support for bioscience research: a collaborative genome center for human chromosome 12.

This paper describes an approach that provides Internet-based support for a genome center to map human chromosome 12, as a collaboration between laboratories at the Albert Einstein College of Medicine in Bronx, New York, and the Yale University School of Medicine in New Haven, Connecticut. Informatics is well established as an important enabling technology within the genome mapping community. The goal of this paper is to use the chromosome 12 project as a case study to introduce a medical informatics audience to certain issues involved in genome informatics and in the Internet-based support of collaborative bioscience research. Central to the approach described is a shared database (DB/12) with Macintosh clients in the participating laboratories running the 4th Dimension database program as a user-friendly front end, and a Sun SPARCstation-2 server running Sybase. The central component of the database stores information about yeast artificial chromosomes (YACs), each containing a segment of human DNA from chromosome 12 to which genome markers have been mapped, such that an overlapping set of YACs (called a "contig") can be identified, along with an ordering of the markers. The approach also includes 1) a map assembly tool developed to help biologists interpret their data, proposing a ranked set of candidate maps, 2) the integration of DB/12 with external databases and tools, and 3) the dissemination of the results. This paper discusses several of the lessons learned that apply to many other areas of bioscience, and the potential role for the field of medical informatics in helping to provide such support.

Chromosome Mapping↗
PubMedDate not supplied

Chemical extraction methods to assess bioavailable arsenic in soil and solid media.

Soil ingestion by children is an important pathway in assessing public health risks associated with exposure to arsenic-contaminated soils. Soil chemical methods are available to extract various pools of soil arsenic, but their ability to measure bioavailable arsenic from soil ingestion is unknown. Arsenic extracted by five commonly used soil extractants was compared with bioavailable arsenic measured in vivo by immature swine (Sus scrofa) dosing trials. Fifteen contaminated soils that contained 233 to 17 500 mg kg(-1) arsenic were studied. Soil extractants were selected to dissolve surficially adsorbed and/or readily soluble arsenic (water, 1 M sodium acetate, 0.1 M Na2HPO4/0.1 M NaH2PO4) and arsenic in Fe and Mn oxide minerals (hydroxylamine hydrochloride, ammonium oxalate). The mean percent of total arsenic extracted was: ammonium oxalate (53.6%) > or = hydroxylamine hydrochloride (51.7%) > phosphate (10.5%), acetate (7.16%) > water (0.15%). The strongest relationship between arsenic determined by soil chemical extraction and in vivo bioavailable arsenic was found for hydroxylamine hydrochloride extractant (r = 0.88, significant at the 0.01 probability level). Comparison of the amount of arsenic extracted by soil methods with bioavailable arsenic showed the following trend: ammonium oxalate, hydroxylamine hydrochloride > in vivo > phosphate, acetate > water. The amount of arsenic dissolved in the stomach (potentially bioavailable) is between surficially adsorbed (extracted by phosphate or acetate) and surficially adsorbed + nonsurficial forms in Fe and Mn oxides (extracted by hydroxylamine hydrochloride or ammonium oxalate). Soil extraction methods that dissolve some of the amorphous Fe, such as hydroxylamine hydrochloride, can be designed to provide closer estimates of bioavailable arsenic.

Animals↗