PubMed Health⌕ Search

Biomedical subjects

Ralph J van Oort

Publications and source records attributed to Ralph J van Oort.

3 recordsLinked to original sources
PubMed2006

EUK-8, a superoxide dismutase and catalase mimetic, reduces cardiac oxidative stress and ameliorates pressure overload-induced heart failure in the harlequin mouse mutant.

OBJECTIVES: The purpose of this study was to identify apoptosis-inducing factor (AIF) as a cardiac mitochondrial antioxidant and assess the efficacy of EUK-8, a salen-manganese catalytic free radical scavenger, to protect the AIF-deficient myocardium against pressure overload. BACKGROUND: Oxidative stress has been postulated to provoke cell death and pathologic remodeling in heart failure. We recently characterized the apoptosis-inducing factor-deficient harlequin (Hq) mouse mutant to display excessive pressure overload-induced oxidative stress, cell death, accelerated progression to heart failure, and a reduced capacity of subsarcolemmal mitochondria to scavenge free radicals, suggesting a role for AIF as a novel mitochondrial antioxidant. METHODS: Oxidative stress-sensitized Hq mutant mice and their wild-type (WT) counterparts were given low-dose EUK-8 (25 mg/kg/day), an antioxidant with superoxide dismutase, catalase, and oxyradical scavenging properties, or vehicle for 4 weeks, and subjected to pressure overload (transverse aortic constriction) for 4 weeks. Myocardial geometry and function was serially assessed by echocardiography. RESULTS: EUK-8 ameliorated survival in Hq and WT mice subjected to pressure overload. EUK-8 also improved left ventricular end-systolic dimensions and fractional shortening, prevented myocardial oxidant stress, attenuated necrotic and apoptotic cell death, and attenuated cardiac hypertrophy and fibrosis in both mutant and WT mice. CONCLUSIONS: The protection against pressure overload-induced heart failure in Hq mice by EUK-8 substantiates the notion that AIF functions as an important mitochondrial antioxidant in the heart. Furthermore, because antioxidant treatment protected both the oxidative stress-prone Hq mouse model and WT mice against pressure overload-induced maladaptive left ventricular remodeling and cardiac decompensation, it may be useful as a novel therapeutic tool in the treatment of human heart failure.

Animals↗
PubMed2006

MEF2 activates a genetic program promoting chamber dilation and contractile dysfunction in calcineurin-induced heart failure.

BACKGROUND: Hypertrophic growth, a risk factor for mortality in heart disease, is driven by reprogramming of cardiac gene expression. Although the transcription factor myocyte enhancer factor-2 (MEF2) is a common end point for several hypertrophic pathways, its precise cardiac gene targets and function in cardiac remodeling remain to be elucidated. METHODS AND RESULTS: We report the existence of synergistic interactions between the nuclear factor of activated T cells and MEF2 transcription factors triggered by calcineurin signaling. To circumvent the embryonic lethality and mitochondrial deficiency associated with germ-line null mutations for MEF2C and MEF2A respectively, we used conditional transgenesis to express a dominant-negative form of MEF2 in the murine postnatal heart and combined this with magnetic resonance imaging to assess MEF2 transcriptional function in Ca2+/calcineurin-induced cardiac remodeling. Surprisingly, end-diastolic and end-systolic ventricular dimensions and contractility were normalized in the presence of severely hypertrophied left ventricular walls on MEF2 inhibition in calcineurin transgenic mice. In line, we generated lines of transgenic mice expressing MEF2A in the heart, which displayed primarily chamber dilation. Microarray profiling indicated that MEF2 promotes a gene profile functioning primarily to or at the nucleus, cytoskeletal and microtubular networks, and mitochondria. CONCLUSIONS: These findings assign a novel function to MEF2 transcription factors in the postnatal heart, where they activate a genetic program that minimally affects cardiac growth yet promotes chamber dilation, mechanical dysfunction, and dilated cardiomyopathy.

Animals↗