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Severe heart failure (HF) is characterized by profound alterations in cardiac metabolic phenotype, with down-regulation of the free fatty acid (FFA) oxidative pathway and marked increase in glucose oxidation. We tested whether fenofibrate, a pharmacological agonist of peroxisome proliferator-activated receptor-␣, the nuclear receptor that activates the expression of enzymes involved in FFA oxidation, can prevent metabolic alterations and modify the progression of HF. We administered 6.5 mg/kg/day p.o. fenofibrate to eight chronically instrumented dogs over the entire period of highfrequency left ventricular pacing (HF ϩ Feno). Eight additional HF dogs were not treated, and eight normal dogs were used as a control. Feno (14.1 Ϯ 1.6 mm Hg) compared with HF (18.7 Ϯ 1.3 mm Hg), but it increased up to 25 Ϯ 2 mm Hg, indicating end-stage failure, in both groups after 29 Ϯ 2 days of pacing. FFA oxidation was reduced by 40%, and glucose oxidation was increased by 150% in HF compared with control, changes that were prevented by fenofibrate. Consistently, the activity of myocardial medium chain acyl-CoA dehydrogenase, a marker enzyme of the FFA ␤-oxidation pathway, was reduced in HF versus control (1.46 Ϯ 0.25 versus 2.42 Ϯ 0.24 mol/min/gram wet weight (gww); p Ͻ 0.05) but not in HF ϩ Feno (1.85 Ϯ 0.18 mol/min/gww; N.S. versus control). Thus, preventing changes in myocardial substrate metabolism in the failing heart causes a modest improvement of cardiac function during the progression of the disease, with no effects on the onset of decompensation.The cardiac metabolic phenotype undergoes profound alterations during heart failure (HF), including defective energy production, lower mechanical efficiency, and a partial shift in energy substrate use . Oxidation of free fatty acids (FFA), which constitutes the preferential energy source for the normal heart, decreases in overt heart failure, whereas glucose oxidation markedly increases. The mechanisms underlying this phenomenon are numerous and complex. There is reduced myocardial expression and activity of key enzymes of the FFA oxidative pathway in different models of human as well as experimental heart failure (Sack et al., 1996;Martin et al., 2000;Rosenblatt et al., 2001;Osorio et al., 2002). The expression of these enzymes is under the control of the peroxisome proliferator-activated receptor (PPAR)-␣ and retinoid X receptor-␣ nuclear receptors that were also found down-regulated in the failing heart (Osorio et al., 2002;Karbowska et al., 2003). Whether such alterations in substrate metabolism play a role in the pathophysiological progression of heart failure remains an open question, with obvious implications for new therapeutic strategies based on metabolic modulators . It has

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Tangier disease is one of the most severe forms of familial high-density lipoprotein (HDL) deficiency. Since its discovery it has been diagnosed in about 100 patients and is characterized by severe plasma deficiency or absence of HDL, apolipoprotein A-I (apoA-I, the major HDL apolipoprotein) and by accumulation of cholesteryl esters in many tissues throughout the body. The biochemical signs of this condition are plasma HDL concentrations less than 5 mg/dL, low total plasma cholesterol (below 150 mg/dL), and normal or high plasma triglycerides. Tangier disease is caused by mutations in the 'ATP-Binding Cassette transporter A1' (ABCA1) gene, which encodes the membrane transporter ABCA1. This transporter plays a key role in the first step of reverse cholesterol transport, through which the efflux of free cholesterol from peripheral cells is transferred to lipid-poor apoA-I. The Tangier disease clinical phenotype is inherited as an autosomal recessive trait, the biochemical phenotype is inherited as an autosomal co-dominant trait. Nearly all the children affected by Tangier disease were identified on the basis of large, yellow-orange tonsils, while half of the adult patients affected by Tangier disease came to medical attention because of symptoms of neuropathy. Diagnosis in the remaining subjects was related to the clinical features of hepatomegaly, splenomegaly, premature myocardial infarction (about 30% of Tangier disease cases) or stroke, thrombocytopenia, anemia, gastrointestinal disorders, corneal opacities, hypocholesterolemia, low HDL cholesterol, or following a familial screening of Tangier patients. To date there is no specific treatment for Tangier disease. Old and recently designed drugs, known to increase HDL levels, have been shown to be ineffective in Tangier patients. The possible and more realistic therapeutic strategy should be designed to obtain a selective increase of mature HDL concentration to restore cholesterol efflux. Recently designed drugs like the cholesteryl ester transfer protein (CETP) inhibitors dalcetrapib and anacetrapib and reconstituted forms of HDL could be considered until the development of gene therapy.