Influence of Age on the Association Between Various Measures of Obesity and All-Cause Mortality

OBJECTIVES: To determine whether the association between various simple measures of obesity and risk for all-cause mortality differs between younger and older men and women.
DESIGN: Prospective cohort study with 8.7 ± 0.2 years of follow-up for mortality linkage.
SETTING: Third National Health and Nutrition Examination Survey, 1988 to 1994.
PARTICIPANTS: Four thousand, four hundred thirty-seven men and 5,166 women.
MEASUREMENTS: Measures of obesity included body mass, waist circumference, waist-to-hip ratio, hip circumference, sum of skinfolds, and bioelectrical impedance.
RESULTS: Overall and abdominal obesity are associated with greater mortality risk in younger adults (<65) ( P <.05), whereas the associations between obesity and mortality are null or inverse in older adults (>65). In general, the association was stronger with measures of abdominal obesity than with measures of overall obesity or fat-free mass.
CONCLUSION: The adverse effects of obesity on mortality risk are apparent only in adults younger than 65. Obesity as characterized using several different measures was not generally associated with greater mortality risk in older adults. Although weight loss is beneficial for reducing morbidity in obese adults of any age, it is unclear whether weight loss is equally beneficial for reducing mortality risk in older adults.     

Characterization of 13 microsatellite loci for the tope shark, Galeorhinus galeus, discovered with next-generation sequencing and their utility for eastern Pacific smooth-hound sharks (Mustelus)

The tope shark, Galeorhinus galeus, is a commercially important member of the Triakidae that has been exploited globally for the past 80 years. Here we describe 13 microsatellite loci for G. galeus discovered by next-generation sequencing (Roche 454 pyrosequencing) and their utility for eastern Pacific smooth-hound sharks (Mustelus). These loci were polymorphic (3–12 alleles) with observed heterozygosity between 0.11 and 0.86 and expected heterozygosity between 0.24 and 0.87. Several loci (7 of 13) amplified consistently for Mustelus californicus and M. henlei. These loci are the first to be characterized explicitly for G. galeus and should be useful in the investigation of population structure of this vulnerable elasmobranch.     

Visual responses in the lateral geniculate evoked by Cx36-independent rod pathways

Emerging evidence indicates rods can communicate with retinal ganglion cells (RGCs) via pathways that do not involve gap-junctions. Here we investigated the significance of such pathways for central visual responses, using mice lacking a key gap junction protein (Cx36^−/−) and carrying a mutation that disrupts cone phototransduction (Gnat2^cpfl3). Electrophysiological recordings spanning the lateral geniculate revealed rod-mediated ON and OFF visual responses in virtually every cell from all major anatomical sub-compartments of this nucleus. Hence, we demonstrate that one or more classes of RGC receive input from Cx36-independent rod pathways and drive extensive ON and OFF responses across the visual thalamus.     

A Finite Element Model of the Foot/Ankle to Evaluate Injury Risk in Various Postures

The foot/ankle complex is frequently injured in many types of debilitating events, such as car crashes. Numerical models used to assess injury risk are typically minimally validated and do not account for ankle posture variations that frequently occur during these events. The purpose of this study was to evaluate a finite element model of the foot and ankle accounting for these positional changes. A model was constructed from computed tomography scans of a male cadaveric lower leg and was evaluated by comparing simulated bone positions and strain responses to experimental results at five postures in which fractures are commonly reported. The bone positions showed agreement typically within 6° or less in all anatomical directions, and strain matching was consistent with the range of errors observed in similar studies (typically within 50% of the average strains). Fracture thresholds and locations in each posture were also estimated to be similar to those reported in the literature (ranging from 6.3 kN in the neutral posture to 3.9 kN in combined eversion and external rotation). The least vulnerable posture was neutral, and all other postures had lower fracture thresholds, indicating that examination of the fracture threshold of the lower limb in the neutral posture alone may be an underestimation. This work presents an important step forward in the modeling of lower limb injury risk in altered ankle postures. Potential clinical applications of the model include the development of postural guidelines to minimize injury, as well as the evaluation of new protective systems.