Multilevel atlas comparisons reveal divergent evolution of the primate brain.

Whether the size of the prefrontal cortex (PFC) in humans is disproportionate when compared to other species is a persistent debate in evolutionary neuroscience. This question has left the study of over/under-expansion in other structures relatively unexplored. We therefore sought to address this gap by adapting anatomical areas from the digital atlases of 18 mammalian species, to create a common interspecies classification. Our approach used data-driven analysis based on phylogenetic generalized least squares to evaluate anatomical expansion covering the whole brain. Our main finding suggests a divergence in primate evolution, orienting the stereotypical mammalian cerebral proportion toward a frontal and parietal lobe expansion in catarrhini (primate parvorder comprising old world monkeys, apes, and humans). Cerebral lobe volumes slopes plotted for catarrhini species were ranked as parietal∼frontal > temporal > occipital, contrasting with the ranking of other mammalian species (occipital > temporal > frontal∼parietal). Frontal and parietal slopes were statistically different in catarrhini when compared to other species through bootstrap analysis. Within the catarrhini's frontal lobe, the prefrontal cortex was the principal driver of frontal expansion. Across all species, expansion of the frontal lobe appeared to be systematically linked to the parietal lobe. Our findings suggest that the human frontal and parietal lobes are not disproportionately enlarged when compared to other catarrhini. Nevertheless, humans remain unique in carrying the most relatively enlarged frontal and parietal lobes in an infraorder exhibiting a disproportionate expansion of these areas.

Paraoxonase-1 and serum concentrations of HDL-cholesterol and apoA-I.

Paraoxonase-1 (PON1) and HDL are tightly associated in plasma, and this is generally assumed to reflect the need for the enzyme to associate with a hydrophobic complex. The association has been examined in coronary cases and age-matched controls. Highly significant (P < 0.0001), positive associations were observed between PON1 activities and concentrations and HDL-cholesterol and apolipoprotein A-I (apoA-I) concentrations in cases and controls. Corrected slopes were significantly different in cases (cases vs. controls: arylesterase, r = 0.19 vs. 0.38, P < 0.02 for apoA-I and r = 0.15 vs. 0.34, P < 0.02 for HDL-cholesterol) such that if PON1 should influence serum HDL, it would be less effective in coronary cases. When examined as a function of the PON1 gene promoter polymorphism C-107 T, highly significant differences (P < 0.001) in HDL-cholesterol and apoA-I were observed between genotypes for controls, with high expresser alleles having the highest HDL concentrations. This relationship was lost in cases with coronary disease. The coding region polymorphisms Q192R and L55M of the PON1 gene showed no association with HDL. The promoter polymorphism was an independent determinant of HDL concentrations in multivariate analyses. These data are consistent with an impact of PON1 on plasma concentrations of HDL, with detrimental modifications to the relationship in coronary cases.

Small, dense lipoprotein particles and reduced paraoxonase-1 in patients with the metabolic syndrome.

The presence of the metabolic syndrome (World Health Organization definition) and its association with lipoprotein abnormalities suggestive of greater susceptibility to oxidative stress have been analyzed in patients with angiographically defined coronary artery disease. The odds ratio for the presence of the metabolic syndrome was significantly higher in coronary artery disease-positive patients (P < 0.001). The metabolic syndrome was also associated with more severe coronary disease (P < 0.01). Patients with the metabolic syndrome had significantly decreased low-density lipoprotein-cholesterol/apolipoprotein B and high-density lipoprotein-cholesterol/apolipoprotein AI ratios, indicative of the presence of small, dense lipoprotein particles. The syndrome was also associated with reduced concentrations and activities of the antioxidant enzyme, paraoxonase-1. The metabolic syndrome is characterized by smaller, denser lipoprotein particles that increase their susceptibility to oxidative modifications and diminished serum paraoxonase-1, which is a major determinant of the antioxidant capacity of high-density lipoproteins. These may be contributory factors to the increased presence and severity of coronary disease in such patients.