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V Menéndez López R Funez G Osman Agha M López Almansa E García 《Canadian Metallurgical Quarterly》1997,21(8):800-802
Middle raphe cysts are very uncommon lesions in the daily clinical practice and can go unnoticed based on their size. We contribute two cases where a quick growth is seen over the last few months. Their histological origin is discussed using specific staining and immunohistochemical techniques. 相似文献
104.
Carolina Gismene Jorge Enrique Hernndez Gonzlez Angela Rocio Nio Santisteban Andrey Fabricio Ziem Nascimento Lucas dos Santos Cunha Fbio Rogrio de Moraes Cristiano Luis Pinto de Oliveira Caio C. Oliveira Paola Jocelan Scarin Provazzi Pedro Geraldo Pascutti Raghuvir Krishnaswamy Arni Ricardo Barros Mariutti 《International journal of molecular sciences》2022,23(17)
Staphylococcal exfoliative toxins (ETs) are glutamyl endopeptidases that specifically cleave the Glu381-Gly382 bond in the ectodomains of desmoglein 1 (Dsg1) via complex action mechanisms. To date, four ETs have been identified in different Staphylococcus aureus strains and ETE is the most recently characterized. The unusual properties of ETs have been attributed to a unique structural feature, i.e., the 180° flip of the carbonyl oxygen (O) of the nonconserved residue 192/186 (ETA/ETE numbering), not conducive to the oxyanion hole formation. We report the crystal structure of ETE determined at 1.61 Å resolution, in which P186(O) adopts two conformations displaying a 180° rotation. This finding, together with free energy calculations, supports the existence of a dynamic transition between the conformations under the tested conditions. Moreover, enzymatic assays showed no significant differences in the esterolytic efficiency of ETE and ETE/P186G, a mutant predicted to possess a functional oxyanion hole, thus downplaying the influence of the flip on the activity. Finally, we observed the formation of ETE homodimers in solution and the predicted homodimeric structure revealed the participation of a characteristic nonconserved loop in the interface and the partial occlusion of the protein active site, suggesting that monomerization is required for enzymatic activity. 相似文献
105.
Mejía-Centeno Isidro Martínez-Hernández Angel Fuentes Gustavo A. 《Topics in Catalysis》2007,42(1-4):381-385
The use of low-sulfur fuel is known to improve the performance of the three-way catalytic converter (TWC). However, in this
work we report how low-sulfur operation of commercial TWC also favors formation of N2O and NH3 as by products. We found that low-sulfur rich operation above 300 °C increases the production of NH3, inhibiting the formation of N2O characteristic of high-sulfur operation. During lean operation, the production of N2O near the stoichiometric point is not significantly affected by the sulfur level. The large production of N2O observed during light-off is not affected by SO2 when the operation is lean, but under rich conditions N2O is produced up to 575 °C. The increased production of NH3 and N2O in TWC as a result of the introduction of low-sulfur gasoline is an area that requires further analysis because of its implication
upon public health in large urban settings. 相似文献
106.
S. Firmino Mendes C. M. Costa R. Sabater i Serra A. Andrio Baldalo V. Sencadas J. L. Gomez-Ribelles R. Gregorio Jr. S. Lanceros-Méndez 《Journal of Polymer Research》2012,19(9):1-14
Poly(vinylidene fluoride)/Pb(Zr0.53Ti0.47)O3([PVDF]1 ? x/[PZT]x ) composites of volume fractions x and (0?C3) type connectivity were prepared in the form of thin films. The films were prepared by solvent casting with PZT powder of 0.84, 1.86, and 2.35???m average size with filler contents up to 40?% volume. The crystalline phase of the polymer matrix was the nonpolar ??-phase and the polar ??-phase. Dielectric measurements were performed in order to evaluate the influence of the filler size and content as well as the effect of the polymer matrix in the overall response of the material. No nucleation effect of any of the phases was observed for the used fillers. The spherulitic structure of the pure ??-PVDF and the characteristic porosity of the ??-phase material are destroyed for high PZT volume fractions. The inclusion of ceramic particles in the PVDF polymer matrix increases the complex dielectric constant of the composites independently of the PVDF polymer matrix. The dielectric properties of the composites are mainly affected by the amount of the ceramic particles. With respect to the relaxation processes of the polymer, the activation energy of the ??a-relaxation increases and the glass transition temperature decreases with increasing particle size and content. The high-temperature conductivity decreases with increasing filler content and there is an important contribution of the Maxwell-Wagner-Sillars effect to the overall dielectric response. 相似文献
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Herrero-Fresno A Martínez N Sánchez-Llana E Díaz M Fernández M Martin MC Ladero V Alvarez MA 《International journal of food microbiology》2012,157(2):297-304
Tyramine and histamine are the biogenic amines (BAs) most commonly found in cheese, in which they appear as a result of the microbial enzymatic decarboxylation of tyrosine and histidine respectively. Given their toxic effects, their presence in high concentrations in foods should be avoided. In this work, samples of three cheeses (Zamorano, Cabrales and Emmental) with long ripening periods, and that often have high BA concentrations, were screened for the presence of BA-degrading lactic acid bacteria (LAB). Seventeen isolates were found that were able to degrade tyramine and histamine in broth culture. All 17 isolates were identified by 16S rRNA sequencing as belonging to Lactobacillus casei. They were typed by plasmid S1-PFGE and genomic macrorestriction-PFGE analysis. Two strains (L. casei 4a and 5b) associated with high degradation rates for both BAs were selected to test how this ability might affect histamine and tyramine accumulation in a Cabrales-like mini-cheese manufacturing model. The quantification of BAs and the monitoring of the strains' growth over ripening were undertaken by RP-HPLC and qPCR respectively. Both strains were found to reduce histamine and tyramine accumulation. These two strains might be suitable for use as adjunct cultures for reducing the presence of BAs in cheese. 相似文献
109.