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Biomedical subjects

Charles D Johnson

Publications and source records attributed to Charles D Johnson.

6 recordsLinked to original sources

In vitro models to evaluate acute and chronic injury to the heart and vascular systems.

Multiple in vitro model systems are currently available to evaluate structure and function relationships in the cardiovascular system as well as the system's response to injury. As the level of molecular sophistication continues to advance, so does the level of complexity of the analysis. One of the most daunting tasks faced by researchers interested in studying cardiovascular function and injury is the selection of the system or systems best suited to answer the particular question at hand. In order to successfully apply any given model system, the researcher must recognize the advantages and limitations in the system of choice. This review provides a listing of the historical and modern techniques used to study cardiovascular function and chemically-induced toxicity. With the growing number of new pharmaceuticals discovered each year, it is imperative to use experimental model systems that allow for identification of targets that participate in or mediate adverse outcomes. Clearly, in vitro analysis cannot replace in vivo experimentation, but the methods currently available allow for a reduction in the number of animals used for experimentation and a better understanding of the complexity associated with the injury response.

Animals↗

Unraveling gene-gene interactions regulated by ligands of the aryl hydrocarbon receptor.

The co-expression of genes coupled to additive probabilistic relationships was used to identify gene sets predictive of the complex biological interactions regulated by ligands of the aryl hydrocarbon receptor ((Italic)Ahr(/Italic)). To maximize the number of possible gene-gene combinations, data sets from murine embryonic kidney, fetal heart, and vascular smooth muscle cells challenged (Italic)in vitro(/Italic) with ligands of the (Italic)Ahr(/Italic) were used to create predictor/training data sets. Biologically relevant gene predictor sets were calculated for (Italic)Ahr(/Italic), cytochrome P450 1B1, insulin-like growth factor-binding protein-5, lysyl oxidase, and osteopontin. Transcript levels were categorized into ternary expressions and target genes selected from the data set and tested for all possible combinations using three gene sets as predictors of transitional level. The goodness of prediction for each set was quantified using a multivariate nonlinear coefficient of determination. Evidence is presented that predictor gene combinations can be effectively used to resolve gene-gene interactions regulated by (Italic)Ahr(/Italic) ligands. (Italic)Key words:(/Italic) aryl hydrocarbon receptor, bioinformatics, gene networks, genomics. (Italic)Environ Health Perspect (/Italic)112:403-412 (2004). [Online 14 January 2004]

Animals↗

Cardiac pacemakers: an update.

In this update of cardiac pacing we review the new revised ACC/AHA/NASPE Guidelines for implantation of cardiac pacemakers, including selection of pacing mode, possible new indications, and other more recent advances in cardiac pacing.

Arrhythmias, Cardiac↗

Cardiac pacemakers.

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Adult↗