The nuclear receptor peroxisome proliferator-activated receptor-␥ (PPAR␥) is critically required ... more The nuclear receptor peroxisome proliferator-activated receptor-␥ (PPAR␥) is critically required for adipogenesis. PPAR␥ exists as two isoforms, ␥1 and ␥2. PPAR␥2 is the more potent adipogenic isoform in vitro and is normally restricted to adipose tissues, where it is regulated more by nutritional state than PPAR␥1. To elucidate the relevance of the PPAR␥2 in vivo, we generated a mouse model in which the PPAR␥2 isoform was specifically disrupted. Despite similar weight, body composition, food intake, energy expenditure, and adipose tissue morphology, male mice lacking the ␥2 isoform were more insulin resistant than wild-type animals when fed a regular diet. These results indicate that insulin resistance associated with ablation of PPAR␥2 is not the result of lipodystrophy and suggests a specific role for PPAR␥2 in maintaining insulin sensitivity independently of its effects on adipogenesis. Furthermore, PPAR␥2 knockout mice fed a high-fat diet did not become more insulin resistant than those on a normal diet, despite a marked increase in their mean adipocyte cell size. These findings suggest that PPAR␥2 is required for the maintenance of normal insulin sensitivity in mice but also raises the intriguing notion that PPAR␥2 may be necessary for the adverse effects of a high-fat diet on carbohydrate metabolism.
We present measurements of the branching fractions, longitudinal polarization, and direct CP-viol... more We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B+ -> rho0 K*+ and B+ -> f0(980) K*+ with a sample of 467+/-5 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory. We observe B+ -> rho0 K*+ with a significance of 5.3 sigma and measure the branching fraction Br(B+ -> rho0 K*+) = (4.6+/-1.0+/-0.4) x 10^{-6}, the longitudinal polarization fL = 0.78+/-0.12+/-0.03, and the CP-violation asymmetry ACP = 0.31+/-0.13+/-0.03. We observe B+ -> f0(980) K*+ and measure the branching fraction Br(B+ -> f0(980) K*+) x Br(f0(980) -> pi+pi-) = (4.2+/-0.6+/-0.3) x 10^{-6} and the CP-violation asymmetry ACP = -0.15+/-0.12+/-0.03. The first uncertainty quoted is statistical and the second is systematic.
The nuclear receptor peroxisome proliferator-activated receptor-␥ (PPAR␥) is critically required ... more The nuclear receptor peroxisome proliferator-activated receptor-␥ (PPAR␥) is critically required for adipogenesis. PPAR␥ exists as two isoforms, ␥1 and ␥2. PPAR␥2 is the more potent adipogenic isoform in vitro and is normally restricted to adipose tissues, where it is regulated more by nutritional state than PPAR␥1. To elucidate the relevance of the PPAR␥2 in vivo, we generated a mouse model in which the PPAR␥2 isoform was specifically disrupted. Despite similar weight, body composition, food intake, energy expenditure, and adipose tissue morphology, male mice lacking the ␥2 isoform were more insulin resistant than wild-type animals when fed a regular diet. These results indicate that insulin resistance associated with ablation of PPAR␥2 is not the result of lipodystrophy and suggests a specific role for PPAR␥2 in maintaining insulin sensitivity independently of its effects on adipogenesis. Furthermore, PPAR␥2 knockout mice fed a high-fat diet did not become more insulin resistant than those on a normal diet, despite a marked increase in their mean adipocyte cell size. These findings suggest that PPAR␥2 is required for the maintenance of normal insulin sensitivity in mice but also raises the intriguing notion that PPAR␥2 may be necessary for the adverse effects of a high-fat diet on carbohydrate metabolism.
We present measurements of the branching fractions, longitudinal polarization, and direct CP-viol... more We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B+ -> rho0 K*+ and B+ -> f0(980) K*+ with a sample of 467+/-5 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory. We observe B+ -> rho0 K*+ with a significance of 5.3 sigma and measure the branching fraction Br(B+ -> rho0 K*+) = (4.6+/-1.0+/-0.4) x 10^{-6}, the longitudinal polarization fL = 0.78+/-0.12+/-0.03, and the CP-violation asymmetry ACP = 0.31+/-0.13+/-0.03. We observe B+ -> f0(980) K*+ and measure the branching fraction Br(B+ -> f0(980) K*+) x Br(f0(980) -> pi+pi-) = (4.2+/-0.6+/-0.3) x 10^{-6} and the CP-violation asymmetry ACP = -0.15+/-0.12+/-0.03. The first uncertainty quoted is statistical and the second is systematic.
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Papers by Antonio Blount