Identification of Oxidized Phosphatidylinositols Present in OxLDL and Human Atherosclerotic Plaque

Oxidized low-density lipoprotein (OxLDL) plays an important role in initiation and progression of atherosclerosis. Proatherogenic effects of OxLDL have been attributed to bioactive phospholipids generated during LDL oxidation. It is unknown what effect oxidation has on the phosphatidylinositol (PtdIns) molecules in LDL, even though PtdIns is 6% of the total LDL phospholipid pool. We sought to identify and quantitate oxidized phosphatidylinositol (OxPtdIns) species in OxLDL and human atherosclerotic plaque. Bovine liver PtdIns was subjected to non-enzymatic and lipoxygenase-catalyzed oxidation. Reversed-phase liquid chromatography with negative ESI–MS identified and confirmed compounds by fragmentation pattern analysis from which an OxPtdIns library was generated. Twenty-three OxPtdIns molecules were identified in copper-oxidized human LDL at 0, 6, 12, 24, 30, and 48 h, and in human atherosclerotic plaque. In OxLDL, OxPtdIns species containing aldehydes and carboxylates comprised 17.3 ± 0.1 and 0.9 ± 0.2%, respectively, of total OxPtdIns in OxLDL at 48 h. Hydroperoxides and isoprostanes at 24 h (68.5 ± 0.2 and 22.8 ± 0.2%) were significantly greater than 12 h (P < 0.01) without additional changes thereafter. Hydroxides decreased with increased oxidation achieving a minimum at 24 h (5.2 ± 0.3%). Human atherosclerotic plaques contained OxPtdIns species including aldehydes, carboxylates, hydroxides, hydroperoxides and isoprostanes, comprising 18.6 ± 4.7, 1.5 ± 0.7, 16.5 ± 7.4, 33.3 ± 1.1 and 30.2 ± 3.3% of total OxPtdIns compounds. This is the first identification of OxPtdIns molecules in human OxLDL and atherosclerotic plaque. With these novel molecules identified we can now investigate their potential role in atherosclerosis.     

Structural features of iron‐phosphate glass

This paper reports a study and discusses the role of Fe ions in the inhibition of corrosion of iron phosphate glasses. The structure of the 40Fe₂O₃–60P₂O₅ (mol%) glass, having a confirmed dissolution rate in aqueous solution at 90°C superior to borosilicate glasses, was investigated. Samples were crystallized at characteristic temperatures defined by differential thermal analysis and analyzed by X‐ray diffraction. Crystalline phases of Fe₂Fe[P₂O₇]₂ and Fe₄[P₂O₇]₃ were detected. The hyperfine parameters from the Mössbauer spectrum indicate that both Fe²⁺ and Fe³⁺ ions are in octahedral coordination, and 18% of the Fe³⁺ ions in the starting batch are reduced to Fe²⁺ ions after melting. The broad and symmetric spectra centered in g≈2.0 from the EPR measurements indicate the presence of two or more Fe interacting ions occupying sites of relatively high local symmetry.     

Rhabdopeptides as Insect‐Specific Virulence Factors from Entomopathogenic Bacteria

Six novel linear peptides, named “rhabdopeptides”, have been identified in the entomopathogenic bacterium Xenorhabdus nematophila after the discovery of the corresponding rdp gene cluster by using a promoter trap strategy for the detection of insect‐inducible genes. The structures of these rhabdopeptides were deduced from labeling experiments combined with detailed MS analysis. Detailed analysis of an rdp mutant revealed that these compounds participate in virulence towards insects and are produced upon bacterial infection of a suitable insect host. Furthermore, two additional rhabdopeptide derivatives produced by Xenorhabdus cabanillasii were isolated, these showed activity against insect hemocytes thereby confirming the virulence of this novel class of compounds.     

Neue Entwicklungen im Bereich Cellulase‐Engineering

Degradation of cellulose represents a key step for efficient generation of biofuels such as ethanol or butanol from non‐food crops. Several strategies aim to improve the performance of cellulases in order to make the overall process more cost‐efficient. In one strategy, novel arrangements of cellulases are developed. The resulting so‐called designer cellulosomes might allow equipping fermenting hosts with sufficient cellulase activity to grow on cellulose as sole carbon source and, thus, enable consolidated bioprocessing. Other strategies aim to engineer cellulases with higher thermostability and activity to make cellulose hydrolysis more efficient. Current developments in the field of cellulose engineering are summarized and achievements as well as limitations are highlighted.     

Experimental investigation of the effect of residual stresses on rapid crack propagation in polyethylene (PE100) pipes

Pipe extruded from polyethylene of strength class PE100 was tested using the ISO 13477 Small Scale Steady State “S4” method, to investigate the effect of frozen‐in stress on rapid crack propagation (RCP). It was found that the lower the residual stress, the lower the S4 critical temperature T_cS4 for RCP. Different experimental thermal treatments were used to independently modify residual stresses and crystallinity, to study the separate effects on RCP. It was found that the effect of crystallinity was less significant than that of residual stresses. It has previously been suggested that the residual stress influence on T_cS4 is determined by the balance of two mechanisms: additional stored strain energy prior to fracture helps to drive the crack, while the closing moment after fracture helps to close the flaring pipe wall. Tests on annealed specimens suggested that the first effect dominates, especially soon after crack initiation. However, the observed effect seems too large to be explained by this mechanism, and we suggest that the observed benefit from annealing may be better explained by a change in crack front shape. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Gas Sensing Behavior of Mesoporous SiOC Glasses

In this study, for the first time, we report the gas sensing behavior of aerogel‐derived silicon oxycarbide (SiOC) glasses. The SiOC glass pyrolyzed at 1400°C has specific surface area of 150 m²/g with pore size in the 2–20 nm range. SiOC sensor shows good response to 5 ppm NO₂ at 300°C. NO₂ response completely disappears at 400°C, and from this temperature SiOC sensor starts respond to H₂. The optimum sensitivity for H₂ is obtained at 500°C. SiOC sensor is very selective; it is not sensitive to other gases such as acetone vapor or CO, even at high concentrations.     

Local and Regional Secondary Organic Aerosol: Insights from a Year of Semi-Continuous Carbon Measurements at Pittsburgh

We present Scanning Mobility CCN Analysis (SMCA) as a novel method for obtaining rapid measurements of size-resolved cloud condensation nuclei (CCN) distributions and activation kinetics. SMCA involves sampling the monodisperse outlet stream of a Differential Mobility Analyzer (DMA) operated in scanning voltage mode concurrently with CCN and condensation particle counters. By applying the same inversion algorithm as used for obtaining size distributions with a scanning mobility particle sizer (SMPS), CCN concentration and activated droplet size are obtained as a function of mobility size over the timescale of an SMPS scan (typically 60–120 s). Methods to account for multiple charging, particle non-sphericity, and limited counting statistics are presented. SMCA is demonstrated using commercial SMPS and CFSTGC instruments with the manufacturer-provided control software. The method is evaluated for activation of both laboratory aerosol and ambient aerosol obtained during the 2004 NEAQS-ITCT2k4 field campaign. It is shown that SMCA reproduces the results obtained with a DMA operating in voltage “stepping” mode.     

Application of a Diffusion Charger for the Measurement of Particle Surface Concentration in Different Environments

Particle surface area has recently been considered as a possible metric in an attempt to correlate particle characteristics with health effects. In order to provide input to such studies, two Nanoparticle Surface Area Monitors (NSAMs, TSI, Inc.) were deployed in different urban sites within Los Angeles to measure the concentration levels and the diurnal profiles of the surface area of ambient particles. The NSAM's principle of operation is based on the unipolar diffusion charging of particles. Results show that the particle surface concentration decreases from ～150 μ m² cm^?3 next to a freeway to ～ 100 μ m² cm^?3 at 100 m downwind of the freeway, and levels decline to 50–70 μ m² cm^?3 at urban background sites. Up to 51% and 30% of the total surface area corresponded to particles < 40 nm next to the freeway and at an urban background site, respectively. The NSAM signal was well correlated with a reconstructed surface concentration based on the particle number size distribution measured with collocated Scanning Mobility Particle Sizers (SMPSs, TSI, Inc.). In addition, the mean surface diameter calculated by combination of the NSAM and the total particle number concentration measured by a Condensation Particle Counter (CPC, TSI, Inc.) was in reasonable agreement with the arithmetic mean SMPS diameter, especially at the urban site. This study corroborates earlier findings on the application of diffusion chargers for ambient particle monitoring by demonstrating that they can be effectively used to monitor the particle surface concentration, or combined with a CPC to derive the mean surface diameter with high temporal resolution.     

Resuspension of Dust Particles in a Chamber and Associated Environmental Factors

Experiments investigating particle resuspension from human activities were conducted in a full-scale experimental chamber. The experiments tested three types of flooring (vinyl tiles, new and old level-loop carpets) and two ventilation configurations (ceiling and side wall supply systems). The floorings were seeded with 0.1–10 μ m test particles. The airborne particle concentration was measured by an array of optical particle counters (OPCs) in the chamber. Resuspension rates were estimated in size ranges of 0.8–1, 1.0–2.0, 2.0–5.0, and 5.0–10 μm ranging from 10^?5–10^?2 hr^?1, with higher resuspension rates associated with larger particles. Resuspension via walking activity varied from experiment to experiment. “Heavy and fast” walking was associated with higher resuspension rates than less active walking, most likely due to a combination of increased pace, increased air swirl velocity, and electrostatic field effects established by the walking. The type of floorings also influenced the particle resuspension. Given the same size and mass distribution of test particles per unit floor area, resuspension rates for the seeded new level-loop carpet were significantly higher than those for the vinyl tile flooring for larger particles (1.0–10 μ m) under the ceiling air supply system.     

Spatial Measurements of Ultrafine Particles Using an Engine Exhaust Particle SizerTM within a Local Community Downwind of a Major International Trade Bridge in Buffalo,New York

Ultrafine particles (UFP) can be defined as having at least one dimension that is less than 100 nanometers. Because of their dimensions, they exhibit unique properties that affect atmospheric transport, exposures, and possibly health endpoints. Freshly generated Diesel particulate matter (DPM) is predominantly in the ultrafine particle size range size range, which in practice is defined by the detection characteristics of the sampling instrument. During two seasons, an Engine Exhaust Particle Sizer^TM (TSI, St. Paul, MN) detects particles over a range of 5.6–560 nm was used to continuously measure real-time particle size distributions along several streets that extend from the Peace Bridge (PB), a major international trade bridge, into a the nearby adjacent neighborhood that has reported a high prevalence rate of asthma (Lwebuga-Mukasa 2000). The Peace Bridge connects Buffalo, NY, USA to Fort Erie, ON, Canada. During summer 2004, one minute average particle number concentrations were continuously monitored along neighborhood streets near the Peace Bridge Complex (PBC) plaza out to about 2 km. Ultrafine particle counts as a function of bridge traffic showed downwind UFP levels at 300 m ranging from 60,000–70,000 p/cm³. Upwind background UFP levels at the shore line of Lake Erie were typically 8,000–10,000 p/cm³ under similar traffic and meteorological conditions. During winter 2006, additional measurements were conducted in front of several homes that were part of a separate indoor-outdoor exposure study (McAuley et al. 2010 McAuley, T. R., Fisher, R., Zhou, X., Jaques, P. A. and Ferro, A. R. 2010. Relationships of Outdoor and Indoor Ultrafine Particles at Residences Downwind of a Major International Border Crossing in Buffalo, NY.. Indoor Air, 20: 298–308. [Crossref] , [Google Scholar]). Sampling at the homes was done during the weekdays when heavy diesel truck traffic was highest. Results showed that most of the UFP number concentrations fell between 10–20 nm in front of homes with UFP levels ranging from 59,000 p/cm³ at couple hundred m downwind to 81,000 p/cm³ several hundred m directly downwind of the Peace Bridge under similar diesel trucks traffic and meteorological conditions.