The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Patrick M. Schlievert - One of the best experts on this subject based on the ideXlab platform.
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The Staphylococcal and Streptococcal Pyrogenic Toxin Family
Advances in Experimental Medicine and Biology, 1996Co-Authors: Gregory A. Bohach, Cynthia V. Stauffacher, Douglas H. Ohlendorf, Gregory M. Vath, Patrick M. SchlievertAbstract:The term “Pyrogenic toxins” describes a group of protein exotoxins (Table 1) produced by organisms in two genera of bacteria, Staphylococcus and Streptococcus. Each Pyrogenic toxin (PT) has unique biological activities, however, they often are grouped collectively into a single toxin family based on an ability that they share to induce multiple systemic effects (Bohach, et al., 1990). These shared activities result from the action of the toxins on the immune, cardiovascular, and other organ systems.
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molecular analysis of Pyrogenic exotoxins from streptococcus pyogenes isolates associated with toxic shock like syndrome
Journal of Clinical Microbiology, 1991Co-Authors: Alan R Hauser, D L Stevens, Edwin L Kaplan, Patrick M. SchlievertAbstract:Toxic shock-like syndrome (TSLS) is characterized by hypotension or shock, fever, multiorgan system involvement, and a concurrent group A streptococcal infection. We analyzed 34 streptococcal strains isolated from patients with clinically well-documented TSLS for their Pyrogenic toxin profiles and M-protein types. Although strains of nine different M types were represented in the sample, 74% of the isolates were of either M type 1 or 3. It was determined that 53% produced streptococcal Pyrogenic exotoxin type A under in vitro growth conditions and that 85% contained the gene encoding this toxin. These values are in contrast to the published value of 15% for the incidence of this gene in a sample of general group A streptococcal isolates. As has been found with all group A streptococci examined to date, regardless of disease association, 100% of TSLS-associated isolates contained the gene encoding Pyrogenic exotoxin type B. This toxin was detectably produced by 59% of isolates. The gene encoding Pyrogenic toxin type C was found in only 21% of isolates. We conclude that the Pyrogenic exotoxin type A gene is associated with group A streptococcal strains isolated from patients with TSLS and may play a causative role in this illness. However, other factors are also likely to be important, since not all strains from patients with TSLS contained the A toxin gene. Images
Zhong Zhang - One of the best experts on this subject based on the ideXlab platform.
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comparative study on the optical surface mechanical and wear resistant properties of transparent coatings filled with Pyrogenic and colloidal silica nanoparticles
Composites Science and Technology, 2011Co-Authors: Hui Zhang, Longcheng Tang, Lingyun Zhou, Christian Eger, Zhong ZhangAbstract:Abstract We applied two kinds of silica nanoparticles, i.e. colloidal and Pyrogenic ones, to improve the performance of transparent coatings on polymer substrates. The urethane–acrylate oligomer was mixed with varied concentrations of silica nanoparticles, spin-coated onto polycarbonate substrate and finally cured by ultraviolet rays. The resultant thickness of the coatings can be controlled in the range of 20–30 μm. The transmission electron microscopy revealed that both silica nanoparticles presented different dispersion states, i.e. mono-dispersion for the colloidal nanoparticles and floc-like dispersion for the Pyrogenic ones. In comparison with the colloidal nanoparticles filled coatings, the Pyrogenic ones exhibited much improved modulus, hardness and wear resistance, but slightly decreased optical properties such as transmittance, haze and gloss. The nanoparticle morphology, amorphous structure, dispersion state and particle–matrix interfacial bonding relating to these properties were discussed in the present study.
P F Bernath - One of the best experts on this subject based on the ideXlab platform.
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ace fts observations of Pyrogenic trace species in boreal biomass burning plumes during bortas
Atmospheric Chemistry and Physics, 2012Co-Authors: K Tereszchuk, Gonzalo Gonzalez Abad, Cathy Clerbaux, Juliette Hadjilazaro, Daniel Hurtmans, Pierrefrancois Coheur, P F BernathAbstract:Abstract. To further our understanding of the effects of biomass burning emissions on atmospheric composition, the BORTAS campaign (BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) was conducted on 12 July to 3 August 2011 during the boreal forest fire season in Canada. The simultaneous aerial, ground and satellite measurement campaign sought to record instances of boreal biomass burning to measure the tropospheric volume mixing ratios (VMRs) of short- and long-lived trace molecular species from biomass burning emissions. The goal was to investigate the connection between the composition and the distribution of these Pyrogenic outflows and their resulting perturbation to atmospheric chemistry, with particular focus on oxidant species to determine the overall impact on the oxidizing capacity of the free troposphere. Measurements of Pyrogenic trace species in boreal biomass burning plumes were made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) onboard the Canadian Space Agency (CSA) SCISAT-1 satellite during the BORTAS campaign. Even though biomass burning emissions are typically confined to the boundary layer, outflows are often injected into the upper troposphere by isolated convection and fire-related convective processes, thus allowing space-borne instruments to measure these Pyrogenic outflows. An extensive set of 14 molecules – CH 3 OH, C 2 H 2 , C 2 H 6 , C 3 H 6 O, CO, HCN, HCOOH, HNO 3 , H 2 CO, NO, NO 2 , OCS, O 3 , and PAN – have been analysed. Included in this analysis is the calculation of age-dependent sets of enhancement ratios for each of the species originating from fires in North America (Canada, Alaska) and Siberia for a period of up to 7 days. Ratio values for the shorter lived primary Pyrogenic species decrease over time primarily due to oxidation by the OH radical as the plume ages and values for longer lived species such as HCN and C 2 H 6 remain relatively unchanged. Increasing negative values are observed for the oxidant species, including O 3 , indicating a destruction process in the plume as it ages such that concentrations of the oxidant species have dropped below their off-plume values. Results from previous campaigns have indicated that values for the molar ratios of ΔO 3 /ΔO obtained from the measurements of the Pyrogenic outflow from boreal fires are highly variable and range from negative to positive, irrespective of plume age. This variability has been attributed to pollution effects where the Pyrogenic outflows have mixed with either local urban NO x emissions or Pyrogenic emissions from the long-range transport of older plumes, thus affecting the production of O 3 within the plumes. The results from this study have identified another potential cause of the variability in O 3 concentrations observed in the measurements of biomass burning emissions, where evidence of stratosphere–troposphere exchange due to the pyroconvective updrafts from fires has been identified. Perturbations caused by the lofted emissions in these fire-aided convective processes may result in the intrusion of stratospheric air masses into the free troposphere and subsequent mixing of stratospheric O 3 into the Pyrogenic outflows causing fluctuations in observed ΔO 3 /ΔCO molar ratios.
Karl-hermann Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Superantigens and pseudosuperantigens of gram-positive cocci
Medical Microbiology and Immunology, 1995Co-Authors: Bernhard Fleischer, Dieter Gerlach, Andreas Fuhrmann, Karl-hermann SchmidtAbstract:Superantigens use an elaborate and unique mechanism of T lymphocyte stimulation. Prototype superantigen are the Pyrogenic exotoxins produced by Staphylococcus aureus and Streptococcus pyogenes . Many candidate proteins of bacterial, viral and protozoal origin have recently been reported to be superantigens. In most cases the evidence that these proteins are in fact superantigens is highly indirect. In this review the evidence that grampositive cocci produce superantigens other than the Pyrogenic exotoxins is critically discussed. Evidence in described demonstrating that the epidermolytic toxins of Staphylococcus aureus and the Pyrogenic exotoxin B and M-proteins of Streptococcus pyrogenes are not superantigens. Criteria are described for acceptance of a candidate as a superantigen.
Paul J Mankiewicz - One of the best experts on this subject based on the ideXlab platform.
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Pyrogenic polycyclic aromatic hydrocarbons in sediments record past human activity a case study in prince william sound alaska
Marine Pollution Bulletin, 1999Co-Authors: David S Page, Paul D Boehm, Gregory S Douglas, A E Bence, William A Burns, Paul J MankiewiczAbstract:Polycyclic aromatic hydrocarbons (PAH) are sensitive recorders of past human activities in Prince William Sound, Alaska. In the nearshore subtidal sediments of bays, the fingerprints of the Pyrogenic (combustion-derived) PAH record numerous sites of both present and historical human activities including active settlements, fish hatcheries, fish camps and recreational campsites, in addition to abandoned settlements, canneries, sawmills, and mining camps. In instances, there are high levels of PAH attributable to past human activities even though there is little remaining visual evidence of these activities on the shorelines. Forest fires are also an important source of Pyrogenic PAH in subtidal sediments at certain time periods and locations and Pyrogenic PAH from atmospheric fallout forms part of the regional PAH background. These Pyrogenic PAH fingerprints are superimposed on a regional background of natural petroleum hydrocarbons derived from seeps in the eastern Gulf of Alaska. In isolated locations, weathered traces of the Exxon Valdez oil spill were detected as a minor part of the total PAH present from all sources.
