PubMed Health⌕ Search

Biomedical subjects

R Fouts

Publications and source records attributed to R Fouts.

6 recordsLinked to original sources
PubMed2001

Decreased p38 MAPK activity in end-stage failing human myocardium: p38 MAPK alpha is the predominant isoform expressed in human heart.

Short duration exposure to cellular stresses have been shown to activate p38 mitogen-activated protein kinase (MAPK) in cultured rat ventricular cardiomyocytes and isolated perfused hearts; however, effects of chronic stress on p38 MAPK are not well understood. This study determined whether alterations in the p38 MAPK pathway occurred prior to end-stage human heart failure. The p38 MAPK alpha isoform was detectable in human cardiac tissue. However, carefully controlled analysis of protein and message in this study demonstrated an absence of the p38 MAPK beta -isoform. Low levels of message for the non-SB203580 sensitive p38 MAPK gamma and delta isoforms were also detected in both normal and failing human myocardium. Ischemic and idiopathic end-stage failing human hearts were compared to non-failing hearts for both p38 alpha MAPK protein level and total p38 MAPK activity. Western blotting techniques demonstrated no significant changes in total p38 alpha MAPK content. However, approximately 75% decreases in active/phosphorylated p38 MAPK (P<0.005) were observed in both ischemic and idiopathic failing hearts compared to non-failing hearts. In-gel kinase assays confirmed that activated p38 MAPK, detected by Western blotting, phosphorylated its potential downstream targets. When compared to non-failing hearts, approximately 46% decreases in p38 MAPK phosphorylation of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK-2) were observed in ischemic and idiopathic failing hearts (P=0.03 and P=0.04 respectively). Active p38 MAPK was localized to sarcomeric structures in the cytosol of myocytes by confocal immunofluorescence microscopy. The correlation between decreased MAPKAPK-2 phosphorylation and loss of active p38 MAPK in failing human myocytes suggests that decreases in the activation of p38 MAPK alpha, the predominant cardiac isoform, occur prior to end-stage heart failure.

Adult↗
PubMed1996

Recombinant human secretory phospholipase A2 released thromboxane from guinea pig bronchoalveolar lavage cells: in vitro and ex vivo evaluation of a novel secretory phospholipase A2 inhibitor.

The primary objective of this study was to develop a functional assay that could provide rapid and reliable information on some pharmacologic characteristics of a novel inhibitor of human secretory phospholipase A2 (sPLA2). Guinea pig bronchoalveolar lavage (BAL) fluid, containing predominantly macrophages, eosinophils and epithelial cells, released thromboxane A2, as measured by thromboxane B2, in a concentration-dependent manner on exposure to recombinant human sPLA2 (rh-sPLA2). Similarly, n-formyl-L-methionyl-L-leucyl-L-phenylalanine (n-F-Met-Leu-Phe) or arachidonic acid also released this lipid mediator. Indomethacin, a cyclooxygenase inhibitor, blocked synthesis of thromboxane in response to these agents. p-Bromophenacylbromide-inactivated rh-sPLA2 was substantially less effective than the untreated enzyme in causing release of thromboxane. LY311727 is a potent indole-derived inhibitor of the isolated enzyme (IC50 = 23 nM). Incubation of this agent with BAL cells, just before addition of rh-sPLA2, reduced release of thromboxane with an IC50 = 1.8 x 10(-6) M. Specificity for sPLA2 was demonstrated in that LY311727, unlike indomethacin, did not reduce synthesis and subsequent release of thromboxane A2 in response to arachidonic acid. Using this technique as a basis, we determined whether LY311727 could sufficiently accumulate in lung after i.v. administration to inhibit rh-sPLA2-induced thromboxane A2 release from BAL cells. The compound, given i.v. to guinea pigs 5 min before collecting BAL fluid, produced a dose-dependent inhibition of rh-sPLA2 with an ED50 = 50 mg/kg. Thus, new in vitro and ex vivo assays were developed that permit functional evaluation of novel sPLA2 inhibitors. These techniques should serve as secondary assays for evaluation of human sPLA2 inhibitory activity from a chemical series and in addition provide initial data related to metabolic stability and distribution to the lung.

Animals↗
PubMed1984

Autoreactivity to collagen in a murine lupus model.

MRL/l mice exhibit many characteristics of human systemic lupus erythematosus including antinuclear antibodies, circulating immune complexes, glomerulonephritis, and death secondary to renal failure. In addition, these mice have elevated levels of rheumatoid factor and spontaneously develop arthritis that has many similarities to human rheumatoid arthritis. Our present studies indicate that, with age, they also develop reactivity to types I and II collagen. The levels of antibodies against native or denatured types I and II collagen in the sera of 4-5-month-old MRL/l mice are significantly higher than those in the sera of age-matched Balb/c or MRL/n mice. The specificity of these antibodies for collagen was demonstrated by a competitive binding assay. The T cells from 1- or 2-month-old MRL/l mice exhibited a significant proliferative response in the presence of type I collagen and a mild or no response to type II collagen. Both antigenic and mitogenic responses decreased with age. The results suggest that the development of autoimmunity to collagen may play an important role in the perpetuation of arthritis, vasculitis, and glomerulonephritis in MRL/l mice.

Animals↗
PubMed1984

Collagen-induced and adjuvant-induced arthritis in rats. Post-immunization treatment with collagen to suppress or abrogate the arthritic response.

Immunization of Lewis rats with native type II collagen results in an inflammatory arthritis and increased humoral and cellular immune responses to type II collagen. The exposure of rats to native type II collagen at day 7 or 10 after immunization suppressed the incidence of arthritis and anticollagen antibody levels, although the cellular response was not affected. The exposure to denatured type II collagen offered partial protection, while type I collagen had no significant effect. Rats immunized with Mycobacterium tuberculosis also showed reduced arthritic response when subsequently treated with type II collagen. The common modalities between the 2 models and the possible role of type II collagen in the interference with the inflammatory arthritic events are discussed.

Animals↗