Thornas M Mckenna

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The brain is a dynamic system that is non-linear at multiple levels of analysis. Characterization of its non-linear dynamics is fundamental to our understanding of brain function. Identifying families of attractors in phase space analysis, an approach which has proven valuable in describing non-linear mechanical and electrical systems, can prove valuable in(More)
Lipopolysaccharide (LPS) treatment impairs cardiac myocyte contractility in a nitric oxide synthase (NOS)-dependent manner. The objective of this study was to assess whether protein kinase C (PKC) transduces the LPS signal into an enhanced NOS activity in rat cardiac myocytes. LPS (100 ng/ml) stimulated myocyte PKC activity, inducible NOS (iNOS) expression,(More)
Treatment of vascular tissue with low levels of lipopolysaccharide (LPS) induces nitric oxide synthase (NOS) activity and diminishes vascular contractility. However, in cultured vascular smooth muscle cells (VSMC), very high doses of LPS or the combination of LPS with cytokines are required for the induction of nitric oxide (NO) formation. The aims of this(More)
We have developed a fuzzy logic-based algorithm to qualify the reliability of heart rate (HR) and respiratory rate (RR) vital-sign time-series data by assigning a confidence level to the data points while they are measured as a continuous data stream. The algorithm's membership functions are derived from physiology-based performance limits and(More)
In vivo endotoxin treatment causes a nitric oxide-mediated hypocontractility in cardiac myocytes. The objective of this study was to assess whether in vitro endotoxin exposure confers similar contractile defects in adult rat cardiac cells. We found that incubation of cardiac myocytes for 6 h with 10-100 ng/ml endotoxin resulted in progressive time- and(More)
Changes in sodium and potassium balance and urinary aldosterone excretion (free plus "acid labile") were surveyed in house mice acclimating initially to 1/2 the ad libitum water ration and later to 1/4 of ad libitum. Each water restriction caused negative sodium and potassium balance, followed by conservation of both ions. At the first water restriction,(More)
The aim of the present study was to test the hypothesis that pulmonary microvascular reactivity is depressed in sepsis and that inducible nitric oxide synthase (iNOS) contributes to the vascular hyporeactivity. Rats were made septic by cecal ligation and puncture. After 16 h, pulmonary vascular reactivity was evaluated by measurement of perfusion pressures(More)
Isolated rat aortas, after incubation in medium conditioned by endotoxin-stimulated peritoneal macrophages, exhibited diminished contraction to norepinephrine (maximal contraction: control medium = 713 +/- 37 (SE) mg tension/mg tissue; medium conditioned by macrophages = 437 +/- 38, P less than .001). Medium containing endotoxin alone or medium conditioned(More)
Treatment of volunteers or animals with endotoxin in vivo results in reduced vascular reactivity to catecholamines. Endotoxin also causes liberation of the vasoactive cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF) from vascular smooth muscle and endothelial cells in culture. This study tested whether defects in contractility could be induced(More)