Use of a serological approach for prediction of Salmonella status in an integrated pig production system

Relevance of a Salmonella serological detection technique was studied from complete results obtained from 9 pigs fattening units. Feces and overshoes were sampled at different periods after starting fattening (2, 3 and 4 months) while caecal contents were taken on the slaughter line. The bacteriological technique used was based on a Diasalm enrichment and a commercial test was used for serology on an average of ten animals per batch. The aim of this work was to establish a correlation between serological results obtained at slaughter (10 samples/batch) and bacteriological results. In this context, two types of logistic regression models were tested by considering alternatively serology and Salmonella detection in caecal contents as the dependent variables. Firstly, beside the fact that all logistic regression models show weak correlations, the first finding was that positive results in overshoes taken at 2 and 3 months are slightly correlated with serological status of herds (odds-ratios of 4.96 and 2.55). Secondly, when batches were characterized as positive on the basis of serological results, the probability of Salmonella recovery in caecal contents was higher than when the batches were considered as negative (odds-ratios comprised between 4.36 and 5.81). A major conclusion is that serology can be used to follow the improvement of an integrated pig production system, but is not the unique solution for assessing risk of Salmonella shedding from specific herds.     

Measurement of Enzymatic and Nonenzymatic Polyunsaturated Fatty Acid Oxidation Products in Plasma and Urine of Macular Degeneration Using LC-QTOF-MS/MS

Oxidized polyunsaturated fatty acids (PUFA) are associated to pathogenesis of diseases including cardiovascular and neurodegeneration. The novel products are not only biomarkers but also lipid mediators in gene regulation and signaling pathways. Herein, simultaneous quantitation of 28 products derived from nonenzymatic and enzymatic oxidation of PUFA i.e. 5-, 15-F_2t-isoprostanes, 7-, 17-F_2t-dihomo-isoprostanes, 7-, 17-F_2t-dihomo-isofurans, 5-, 8-, 18-F_3t-isoprostanes, 4-, 10-, 13-, 14-, 20-F_4t-neuroprostanes, 5-, 8-, 9-, 11-,12-, 15-, 20-HETE, 4-, 7-, 11-, 14-, 17-HDHA, RvE1, and NPD1 using LC-(ESI)-QTOF-MS/MS was developed. These products were measurable in a single sample and the analytical time was relative short (~15 min). Furthermore, we showed that the use of internal standards is a requisite to normalize matrix effects and preparation loss for the quantitation. Validation assays indicated the method to be robust for plasma and mid-stream urine sample analysis in particular from those of age-related macular degeneration subjects, where the accuracy of quantitation displayed good repeatability.     

Human Skin Volatiles: A Review

Odors emitted by human skin are of great interest to biologists in many fields; applications range from forensic studies to diagnostic tools, the design of perfumes and deodorants, and the ecology of blood-sucking insect vectors of human disease. Numerous studies have investigated the chemical composition of skin odors, and various sampling methods have been used for this purpose. The literature shows that the chemical profile of skin volatiles varies greatly among studies, and the use of different sampling procedures is probably responsible for some of these variations. To our knowledge, this is the first review focused on human skin volatile compounds. We detail the different sampling techniques, each with its own set of advantages and disadvantages, which have been used for the collection of skin odors from different parts of the human body. We present the main skin volatile compounds found in these studies, with particular emphasis on the most frequently studied body regions, axillae, hands, and feet. We propose future directions for promising experimental studies on odors from human skin, particularly in relation to the chemical ecology of blood-sucking insects.     

Lack of Evidence for HLA-Linked Patterns of Odorous Carboxylic Acids Released from Glutamine Conjugates Secreted in the Human Axilla

Genetic factors within the major histocompatibility locus (MHC) have been shown to influence body odors in mice. MHC-dependent preferences for body odors also have been reported in humans. The axillary glands are a key odor-forming organ in humans, and it is assumed that they provide behaviorally relevant odors. Volatile carboxylic acids are the most diverse class of known axillary odorants, and the pattern of these acids is genetically determined. These acids are released by an N_α-acyl-glutamine-aminoacylase present in skin bacteria. We tested a hypothesis concerning whether or not the inherited individual-specific patterns of odorous acids are strongly influenced by polymorphic genes in the MHC. Axilla secretions were collected in 12 families, comprising 3 to 6 siblings, who had been typed for HLA-A, B, and DRB1 loci. The samples were treated with N_α-acyl-glutamine-aminoacylase, and the methyl esters of the released acids were analyzed with comprehensive two-dimensional gas chromatography (GC × GC) and time-of-flight mass spectrometry (ToF MS). The patterns of the analytes were compared by distance analysis. The distance was lowest between samples taken from the same individual, confirming the presence of donor-specific odor-prints. A much higher distance was observed between siblings, but there were no differences among siblings sharing none, one, or both HLA-A,B,DRB1 haplotypes. By applying principal component analysis, a clear clustering of samples taken from one individual was confirmed, but no clustering was observed for siblings sharing identical HLA-A,B,DRB1 alleles. Thus, the genetically determined pattern of N-acyl-glutamine conjugates of volatile carboxylic acids, secreted in the human axilla, appears not to be determined by genes residing in the HLA complex.     

So Useful,Those Quasicrystals

For years, the community working on quasicrystals in many countries in the world was expecting the ultimate recognition of its contribution to the advancement of crystal chemistry, solid-state physics, mathematics, and other fields. Nearly thirty years after the initial discovery, it was finally awarded in October 2011 to Prof. Danny Shechtman by the Nobel Committee for Physics and Chemistry. Many, most often independent, achievements contributed to this success. The purpose of this article is to chronicle the role played by the applications of quasicrystals and related compounds in the development of the field and its financing by governmental institutions as well as private companies. Those applications, potential or realized, have made the field of quasicrystals comprehensible to the general public and to decision makers all over the world, including in Stockholm, in spite of its rather complicated high-dimensional crystallographic background, and in spite of the absolute opposition that a great chemist manifested against it in its infancy.     

Facile synthesis and promising antibacterial properties of a new guaiacol-based polymer

A new acrylamide-type monomer (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide) derived from guaiacol was successfully synthesized. Polymers containing guaiacol moiety were obtained via conventional radical polymerization of this monomer with AIBN as initiator. The influence of reaction time, initiator concentration and temperature on polymers characteristics was studied. Evaluation of the termination mode in free-radical polymerization was performed by MALDI-TOF mass spectrometry. Termination occurs mainly by disproportionation reaction. Additional peaks in the spectrum were attributed to side chain reactions implying phenoxy radicals. This new polymer exhibits a potential antibacterial activity against Bacillus subtilis by using anti-adhesion and anti-biofilm tests. After an adhesion time of 3 h, compared to a non-coated glass slide, there was a decrease of bacteria of 99% on the polymer coated glass slide. After three days of culture in a bacterial suspension, no biofilm was observed on the polymer coated surface.     

Influence of 6-Amino chrysene on the Kinetics of the Metabolic Process for 9-Hydroxybenzo(a)pyrene in 3T3 and RTG2 Cells

PAH metabolism is known to proceed in two successive steps, the first one resulting in the production of activated metabolites which are subsequently transformed by the different pathways involved in the second step. Microspectrofluorometry enables us to study the kinetics of these steps in living intact cells in which no imbalance has been introduced artificially. We have used this technique in order to check the influence of 6-Amino-chrysene (6 AC) on the kinetics of the metabolism of 9-Hydroxybenzo(a)pyrene (9-OH-B(a)P) which, in a previous study, had been shown to proceed mainly through the glucuronide pathway. We have first demonstrated that both 6 AC and 9-OH-B(a)P were good substrates for Rabbit Glucuronic Transferase. Then using RTG2 and 3T3 cells, we have verified that the glucuronide pathway was strongly involved in the metabolism of 6 AC. Finally we have demonstrated that 6 AC strongly inhibits the metabolism of 9-OH-B(a)P in both cell lines. Such results are consistent with a competition of both compounds for the same binding site of GTAse 1.     

Identification of trigger factors selecting for polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge sequencing batch reactors

Nutrient removal performances of sequencing batch reactors using granular sludge for intensified biological wastewater treatment rely on optimal underlying microbial selection. Trigger factors of bacterial selection and nutrient removal were investigated in these novel biofilm systems with specific emphasis on polyphosphate- (PAO) and glycogen-accumulating organisms (GAO) mainly affiliated with Accumulibacter and Competibacter, respectively. In a first dynamic reactor operated with stepwise changes in concentration and ratio of acetate and propionate (Ac/Pr) under anaerobic feeding and aerobic starvation conditions and without wasting sludge periodically, propionate favorably selected for Accumulibacter (35% relative abundance) and stable production of granular biomass. A Plackett-Burman multifactorial experimental design was then used to screen in eight runs of 50 days at stable sludge retention time of 15 days for the main effects of COD concentration, Ac/Pr ratio, COD/P ratio, pH, temperature, and redox conditions during starvation. At 95% confidence level, pH was mainly triggering direct Accumulibacter selection and nutrient removal. The overall PAO/GAO competition in granular sludge was statistically equally impacted by pH, temperature, and redox factors. High Accumulibacter abundances (30–47%), PAO/GAO ratios (2.8–8.4), and phosphorus removal (80–100%) were selected by slightly alkaline (pH > 7.3) and lower mesophilic (<20 °C) conditions, and under full aeration during fixed 2-h starvation. Nitrogen removal by nitrification and denitrification (84–97%) was positively correlated to pH and temperature. In addition to alkalinity, non-limited organic conditions, 3-carbon propionate substrate, sludge age control, and phase length adaptation under alternating aerobic-anoxic conditions during starvation can lead to efficient nutrient-removing granular sludge biofilm systems.     

Views on R&D needs about in-vessel reflooding issues, with a focus on debris coolability

In-vessel reflooding during a severe accident in a PWR was analyzed in 2000–2002 by a group of experts with the aim to prepare a global IRSN R&;D strategy to answer the corresponding pending safety issues. Indeed, water is today systematically injected if available during a severe accident in a PWR. However, knowledge on consequences of such an injection is not complete and answers are necessary for accident management in present PWR as well for design and safety analysis of future PWR: is in-vessel corium retention possible? What is the kinetics of hydrogen production? What is the reactor cooling system (RCS) re-pressurization? Is there a risk of steam explosion (steam explosion is not discussed in this paper)? What is the impact on source term? And more generally, how to optimize water injection? (When? How?) R&;D needs of investigation of these aspects were identified. This should cover separate-effect and integral tests, as well as modeling and code development.The approach consisted first in updating the synthesis of knowledge, based on the multiple reports released in an international frame (OECD, European Commission (EC) Framework Programs (FwP), …), and then in focusing on a detailed re-analysis of the most important experiments CORA, QUENCH, LOFT-LP-FP2 and of TMI-2 accident, the latter two being directly related to debris coolability phenomena. Several out-of-pile experiments on debris bed coolability were also analyzed.A qualitative analysis of different possible core degradation scenarios was performed for French PWR, depending on operator actions or procedures. Simplified and mechanistic models were used to evaluate orders of magnitude of the phenomena in reactor conditions.A Phenomena Identification Ranking Table (PIRT) ranked the elementary phenomena with respect, on one hand, to their importance from the point of view of safety consequences and, on the other hand, to their level of understanding (often based on experts opinion). In particular, coolability of debris either in the core or in the lower plenum was identified as an important issue to be solved: uncertainties were underlined on debris characterization (size, distribution, composition, …) and on multi-D thermal–hydraulics in a debris bed. This ranking is fully consistent with the outcomes of the EURSAFE 5th FwP project. Existing or future experiments that could satisfy the needs were then identified, including for debris coolability POMECO, DEBRIS, STYX, etc. This specific issue will be analyzed in the frame of the Network of Excellence on severe accidents SARNET which has started in 2004 in the 6th FwP. Further model developments are being performed in the IRSN codes ICARE/CATHARE (detailed modeling) and ASTEC (simplified fast-running modeling), the latter being jointly developed with GRS.     

Mechanical properties of NBR/clay nanocomposites by using a novel testing system

NBR/clay nanocomposites are prepared by two different filler types: clay microparticles and clay nanoparticles. The morphology properties of all specimens are explored by XRD and SEM. The mechanical properties are characterized by means of a novel video-controlled method under uniaxial tension. Apart a limited increase in tensile stress at small strains, the ultimate stress at rupture of nanocomposites is much higher than microcomposites. The most dramatic phenomenon is the development of volume strain while the materials are stretched. The nucleation of voids is much more active in composites containing the filler with higher specific surface when the cavitation occurs at the poor interface between the clay platelets and the rubber matrix. In turn, the existence of very diffuse voids hinders the propagation of cracks and retards the rupture process. DMA results reveal that the interfacial action of NBR molecules with layered silicates increases with the degree of intercalation.