Expert Panel Workshop Consensus Statement on the Role of the Environment in the Development of Autoimmune Disease

Autoimmune diseases include 80 or more complex disorders characterized by self-reactive, pathologic immune responses in which genetic susceptibility is largely insufficient to determine disease onset. In September 2010, the National Institute of Environmental Health Sciences (NIEHS) organized an expert panel workshop to evaluate the role of environmental factors in autoimmune diseases, and the state of the science regarding relevant mechanisms, animal models, and human studies. The objective of the workshop was to analyze the existing data to identify conclusions that could be drawn regarding environmental exposures and autoimmunity and to identify critical knowledge gaps and areas of uncertainty for future study. This consensus document summarizes key findings from published workshop monographs on areas in which “confident” and “likely” assessments were made, with recommendations for further research. Transcribed notes and slides were reviewed to synthesize an overview on exposure assessment and questions addressed by interdisciplinary panels. Critical advances in the field of autoimmune disease research have been made in the past decade. Collaborative translational and interdisciplinary research is needed to elucidate the role of environmental factors in autoimmune diseases. A focus on exposure assessment methodology is needed to improve the effectiveness of human studies, and more experimental studies are needed to focus on causal mechanisms underlying observed associations of environmental factors with autoimmune disease in humans.     

Biosynthesis of medium-chain triacylglycerols and phospholipids by HepG-2 cells

In an attempt to understand the metabolism by the liver of fatty acids (FA) of different chain length, we have studied the incorporation of [1-¹⁴C]-labeled C₂, C₈, C₁₀, C₁₂, and C₁₆ into cellular lipids by HepG-2 cells. Over 90% of the radiolabeled FA were detected in phospholipids (PL) and triacylglycerols (TAG). The incorporation of C₁₂ and C₁₆ was three to four times higher than that of C₈ and C₁₀ (and reached 35 nmoles per mg protein after 1.5 h). The radioactivity of C₂, C₈, and C₁₀ was recovered mainly in PL. C₁₂ and C₁₆ were incorporated at approximately equal amounts into PL and TAG. The radioactivity of both C₂ and C₈ was recovered exclusively in long-chain FA, suggesting oxidation of C₈ into C₂ units prior to FA synthesis. C₁₀ likewise yielded mainly long-chain FA. However 10% of unchanged C₁₀ was found in PL and up to 30% in TAG. ¹⁴C–C₁₂ was largely incorporated unchanged. Under these conditions, the presence of C₁₀ and C₁₂ in PL and TAG was shown also by gas-liquid chromatography. In the presence of either C₂, C₈, or C₁₀, up to 30% of ¹⁴C-monounsaturated FA were detected in PL and TAG. With C₁₂ and C₁₆, the fraction of ¹⁴C-monounsaturated FA was much smaller suggesting that extensive desaturation occurred during de novo synthesis.     

Correlation Between the Total Morphology of an Epoxy System and Some of its Properties

Due to the ever growing use of epoxy resins for structural applications, more information is required about their structure-properties relationship. Much work was done on this subject by us and by others, but many questions still remain unanswered. Some problems which require more detailed studies are the influence of factors like compositional changes in the resin (ratio of prepolymer-curing agent), postcuring and cooling of the polymerized resin from temperatures above T_g to room temperature, on physical properties of the product.     

Exhumed Geogrid-Reinforced Retaining Wall

An instrumented geogrid-reinforced wall constructed on a highly compressible foundation was deconstructed 16 months after its completion, providing a unique opportunity to exhume and examine the instrumented geogrids that were used to construct the wall. The objectives of this post mortem study were: (1) to inspect the condition of the strain gauges that were attached to the geogrid layers before construction and to verify the reliability of their output; (2) to develop a procedure in which the residual (plastic) strains along exhumed geogrid panels could be determined; and (3) to assess the in situ strain and force distribution along geogrid panels based on the measured residual strains from the exhumed geogrids. After exhumation, it was observed that many of the attached strain gauges failed due to full or partial debonding from the geogrid, thus rendering outputs which potentially underestimated the actual strain. Combining aperture measurements of virgin and exhumed geogrids, all from the same manufacturing lots, enabled the assessment of residual strains following stress relaxation. Laboratory simulation of loading and unloading, including creep and relaxation, yielded a relationship between the measured residual strains and the in situ strain and force distribution; i.e., the residual strain fingerprint provided insight into the behavior of the geogrids within the wall prior to its deconstruction. The mobilized maximum tensile strains in the geogrid panels along the height of the wall were roughly uniform, in the range 4±1%. These findings imply that if the same type of reinforcement had been used throughout the height of the wall, the mobilized force along the height would have been relatively uniform. The back-calculated maximum force in the geogrids indicated that the factor of safety on the long-term strengths of the geogrids ranged from about 1.4 on the stronger/stiffer geogrid to about 1.8 on the weaker/softer geogrid.     

Tin Oxide Thin-Film Sensors for Aromatic Hydrocarbons Detection: Effect of Aging Time on Film Microstructure

SnO₂ thin films for gas-sensor devices were deposited by pulsed laser ablation on < h 00> silicon wafers and on substrate heater elements with 200 nm thick Si₃N₄ membranes as physical supports of the sensor stack. Microscopic analysis showed that the thin films were polycrystalline, with ∼40-60 nm equiaxial grains, high porosity, and high specific surface area. The sensors were exposed to gas mixtures containing benzene, wet synthetic air, and CO, with 0.5 ppm of benzene added to 30% relative humidity synthetic air and 20 ppm CO. A 100% relative conductance variation, Delta I / I ₀, of the sensing layer was observed. However, this Delta I / I ₀ value consistently decreased after prolonged testing (up to 2 weeks) in a gas-sensor chamber. The sensing layer was studied using several analytical techniques to understand the aging time effects on sensor performance under working conditions. X-ray diffractometry showed a marked decrease of the residual microstrain after prolonged heat treatments, suggesting a substantial reduction of lattice (point and line) defects. Furthermore, photothermal deflection spectroscopy highlighted a consistent decrease of the sensing layer absorption coefficient near 1 eV that could be related to a reduction of carrier concentration. Because structural defects in SnO₂, such as oxygen vacancies or dislocations, are electrically active and variations in the carrier concentration are, at least in part, related with changes in the defect density, the annealing of these defects might have accounted for the observed worsening of sensor performance with the aging time.     

Seasickness as a self-fulfilling prophecy: Raising self-efficacy to boost performance at sea.

Applying the self-fulfilling prophecy (SFP) approach to combating seasickness, the authors experimentally augmented the self-efficacy of naval cadets by telling them that they were unlikely to experience seasickness and that, if they did, it was unlikely to affect their performance at sea. Naval cadets (N?=?25) in the Israel Defense Forces were randomly assigned to experimental and control conditions. At the end of a 5-day training cruise, experimental cadets reported less seasickness and were rated as better performers by naive training officers than were the control cadets. There was a nonsignificant tendency for the experimental effects to be stronger among cadets of lower initial self-efficacy, suggestive of behavioral plasticity. Reducing seasickness by verbally enhancing self-efficacy is discussed as an application of "verbal placebo." These findings extend the generalizability of the SFP-at-work model and suggest new arenas for its practical application. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fracture Toughness Evaluation of Small Thin Ceramic Specimens

A test method to evaluate the fracture toughness, K_IC, of thin, small, precracked ceramic specimens is described. The method is applicable for thin plates, wafers, self-supported layers, etc., especially when a large amount of material is not available for testing. The method consists of bonding a small, thin single-edge notched beam on one side of a metallic beam. A stress-free precrack with a square root singularity is achieved when the assembly is deformed in three-point bending.
The fracture toughness of a thin, alumina single-edge precracked beam was evaluated experimentally using this method, and compared with that obtained for similar specimens having a 0.3-mm-wide machined notch. Comparison with previously reported fracture toughness values suggests that even a very sharp machined notch overestimates the evaluated fracture toughness.