Search

Caviomorph rodents have been diverse and abundant components of South American mammal communities since the late Eocene. We describe herein the octodontoids of Pampa Castillo, a Lower Miocene site in southern Chile (Aysén Region). Six genera and seven species of octodontoids are present, two of which are new: Dudumus berggreni sp. nov. and Caviocricetus guenekko sp. nov. The octodontoids from Pampa Castillo support assignment of this fauna to the Santacrucian South American Land Mammal Age (SALMA), which is consistent with previous studies. We conducted similarity analyses on 11 Early–Middle Miocene Patagonian rodent faunas using hierarchical clustering. Faunas generally fell into the three SALMAs to which they were traditionally assigned: Colhuehuapian, Santacrucian and 'post‐Santacrucian'. The 'Pinturan' is a proposed biochronological interval between the Colhuehuapian and Santacrucian. At the genus level, Pampa Castillo clustered with 'Pinturan' faunas, while at the species level it clustered with the 'typical' faunas on which the Santacrucian SALMA is based (from outcrops of the Santa Cruz Formation along the Atlantic coast and Río Santa Cruz). The Pampa Castillo rodent fauna resembles both 'Pinturan' and 'typical' Santacrucian faunas in taxon distributions, reflecting complex temporal and palaeoenvironmental influences. Geochronological data indicate that some 'Pinturan' sites overlap temporally with Pampa Castillo and the upper Pinturas Formation, which both clustered with 'typical' Santacrucian faunas. These results indicate that the 'Pinturan' does not represent a distinct biochronological interval, but that the differences between it and 'typical' Santacrucian faunas are attributable to geographic or palaeoenvironmental differences. [ABSTRACT FROM AUTHOR]

Background: Recent literature suggests that the Western diet's imbalance between high ω-6 (n-6) and low ω-3 (n-3) PUFA intake contributes to fatty liver disease in obese youth.Objectives: We tested whether 12 wk of a low n-6:n-3 PUFA ratio (4:1) normocaloric diet mitigates fatty liver and whether the patatin-like containing domain phospholipase 3 (PNPLA3) rs738409 variant affects the response.Methods: In a single-arm unblinded study, obese youth 9-19 y of age with nonalcoholic fatty liver disease were treated with a normocaloric low n-6:n-3 PUFA ratio diet for 12 wk. The primary outcome was change in hepatic fat fraction (HFF%), measured by abdominal MRI. Metabolic parameters included alanine aminotransferase (ALT), lipids, measures of insulin sensitivity, and plasma oxidized linoleic acid metabolites (OXLAMs). Outcomes were also analyzed by PNPLA3 rs738409 genotype. Wilcoxon's signed rank test, the Mann-Whitney U test, and covariance pattern modeling were used.Results: Twenty obese adolescents (median age: 13.3 y; IQR: 10.5-16.4 y) were enrolled and 17 completed the study. After 12 wk of dietary intervention, HFF% decreased by 25.8% (P = 0.009) despite stable weight. We observed a 34.4% reduction in ALT (P = 0.001), 21.9% reduction in triglycerides (P = 0.046), 3.28% reduction in LDL cholesterol (P = 0.071), and a 26.3% improvement in whole body insulin sensitivity (P = 0.032). The OXLAMs 9-hydroxy-octadecandienoic acid (9-HODE) (P = 0.011), 13-HODE (P = 0.007), and 9-oxo-octadecadienoic acid (9-oxoODE) (P = 0.024) decreased after 12 wk. HFF% declined in both the not-at-risk (CC/CG) and at-risk (GG) PNPLA3 rs738409 genotype groups, with significant (P = 0.016) HFF% reduction in the GG group. Changes in 9-HODE (P = 0.023), 9-oxoODE (P = 0.009), and 13-oxoODE (P = 0.003) differed between the 2 genotype groups over time.Conclusions: These data suggest that, independently of weight loss, a low n-6:n-3 PUFA diet ameliorates the metabolic phenotype of adolescents with fatty liver disease and that response to this diet is modulated by the PNPLA3 rs738409 genotype.This trial was registered at clinicaltrials.gov as NCT01556113. [ABSTRACT FROM AUTHOR]

Recent literature suggests that the dietary imbalance between high omega-6 (n6) and low omega-3 (n3) polyunsaturated fatty acids (PUFA) intake, characteristic of the Western diet (average ratio 15:1), leads to development of fatty liver disease. We aimed to determine whether 12 weeks of a low n6/n3 PUFA ratio (4:1) normo-caloric diet might impact fatty liver (MRI assessed hepatic fat content ≥5.5%). Twenty obese adolescents with fatty liver were recruited (13.2±2.9y). Abdominal MRI and OGTT were performed at baseline and after 12-weeks intervention, the oxidized derivatives of linoleic acid (OXLAM) were measured every 4 weeks to assess compliance. Food was supplied to participants isocaloric to their pre-study diet. To control for weight change variable, weight was maintained stable throughout the study. Seventeen adolescents completed the study. After 12 weeks HFF%, decreased of about 26% (Figure 1). There was also a significant decrease in plasma concentrations of ALT (Figure 1), triglycerides (p=0.04) cholesterol (p=0.03), LDL (p=0.07) and an improvement of whole-body insulin resistance (p=0.01). There was a significant decrease of the OXLAM, 9- and 13-HODE (p=0.03 and p=0.01, respectively) and 9- and 13-oxo-ODE (p=0.05 and p=0.01, respectively). These data suggest that, independent of weight loss, a low n6/n3 PUFA diet is effective to ameliorate the metabolic phenotype of adolescents with fatty liver disease. Disclosure: M.A. Van Name: Research Support; Self; Novo Nordisk Inc. J.M. Chick: None. M. Savoye: None. B. Pierpont: None. B. Galuppo: None. A. Feldstein: None. N. Santoro: None. Funding: National Institutes of Health; American Heart Association [ABSTRACT FROM AUTHOR]