Virulence Factors IN Fungi of Systemic Mycoses

Fatores de virulência em fungos de micoses sistêmicaFungos patogênicos causadores de micoses sistêmicas possuem vários fatores que permitem seu crescimento nas condições adversas oferecidas pelo hospedeiro, propiciando o estabelecimento da relação parasitária e contribuindo no processo de doença. Esses fatores são conhecidos como fatores de virulência auxiliando no desenvolvimento da infecção e interferindo com a patogênese das micoses. O presente trabalho avalia os fatores de virulência em fungos patogênicos como Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum e Paracoccidioides brasiliensis, em relação à termotolerância, dimorfismo, componentes da parede celular ou cápsula, bem como a produção de enzimas. Os fatores de virulência auxiliam na aderência, colonização, disseminação e habilidade do fungo para resistir a ambientes hostis e escapar dos mecanismos da resposta imune do hospedeiro.Tanto os fatores de virulência apresentados por diferentes fungos, como os mecanismos de defesa oferecidos pelo hospedeiro requerem ação e interação de processos complexos, cujo conhecimento permitirá a melhor compreensão da patogenia das micoses sistêmicas.

Correlation of reactivity with structural factors in a series of Fe(II) substituted cobalt ferrites

A series of powdered cobalt ferrites, CoxFe3-xO4 with 0.66 <= x< 1.00 containing different amounts of Fe-II, were synthesized by a mild procedure, and their Fe and Co site occupancies and structural characteristics were explored using X-ray anomalous scattering and the Rietveld refinement method. The dissolution kinetics, measured in 0.1 M oxalic acid aqueous solution at 70 degrees C, indicate in all cases the operation of a contracting volume rate law. The specific rates increased with the Fell content following approximately a second-order polynomial expression. This result suggests that the transfer of Fe-III controls the dissolution rate, and that the leaching of a first layer of ions Co-II and Fe-II leaves exposed a surface enriched in slower dissolving octahedral Fe-III ions. Within this model, inner vicinal lattice Fe-II accelerates the rate of Fe-III transfer via internal electron hopping. A chain mechanism, involving successive electron transfers, fits the data very well. (C) 2006 Elsevier B.V. All rights reserved.

LACK OF VIRULENCE FACTORS IN ESCHERICHIA-COLI STRAINS OF ENTEROPATHOGENIC SEROGROUPS ISOLATED FROM WATER

Thirty-eight Escherichia coli strains belonging to 14 human enteropathogenic serogroups were isolated from 33 of 208 water samples studied. No virulence factor or virulence-related gene sequences were found in any of the 38 strains analyzed. The results point out the importance of detecting specific virulence factors before incriminating water as a source of human diarrhea.

PATH-ORDERED PHASE-FACTORS IN SCALAR QUANTUM ELECTRODYNAMICS

Starting from linear equations for the complex scalar field, the two- and three-point Green's functions are obtained in the infrared approximation. We show that the infrared singularity factorizes in the vertex function as in spinor QED, reproducing in a simple and straightforward way the result of lengthy perturbative calculations.

Well productivity controlling factors in crystalline terrains of southeastern Brazil

Over the last decades, increasing water demands have fostered research to obtain high well yields in crystalline terrains where, besides the intrinsic properties of rocks, the groundwater flow depends on several factors. The depth of the wells, the lithotypes, the presence and thickness of sedimentary coverings and weathered layers, the landforms, the geological structures, and the effects of tectonic stresses are among the most investigated factors considered as determinant of well productivity. The influence of these factors on productivity of wells that exploit the Crystalline Aquifer System in the Jundiai-River Catchment, southeastern Brazil, is investigated in this work. The largest region of the studied area is located on the Precambrian Basement, partially covered by sedimentary deposits. The results show that the sedimentary deposits and the weathered layer are important for high well yield, but it also depends on the existence of a net of open fractures, in order to maintain high productivity. The sites that have more possibility of occurrence of such structures are the regional shear and fault zones and other minor structures with NW-SE and E-W directions, which characterize areas subjected to transtensional stress related to the neotectonics.

The slippery slope - Critical perspectives on in vitro research methodologies

Objectives. This paper attempts to provide critical perspectives on common in vitro research methodologies, including shear bond testing, wear testing, and load-to-failure tests. Origins of interest in high-quality laboratory data is reviewed, in vitro data is categorized into property and simulation protocols, and two approaches are suggested for establishing clinical validity. It is hoped that these insights will encourage further progress toward development of in vitro tests that are validated against clinical performance and/or by producing clinically validated failure or damage mechanisms.Materials and methods. Published shear and tensile bond data (macro and micro) is examined in light of published finite element analyses (FEA). This data is subjected to a Weibull scaling analysis to ascertain whether scaling is consistent with failure from the bonded interface or not. Wear tests results are presented in light of the damage mechanism(s) operating. Quantitative wear data is re-examined as being dependent upon contact pressure. Load-to-failure test results are re-analyzed by calculating contact stresses at failure for 119 tests from 54 publications over more than 25 years.Results. FEA analyses and reported failure modes (adhesive, mixed, cohesive) are consistent with failure not involving interfacial "shear stresses" as calculated in published work. Weibull scaling clearly suggests failure involving external surfaces of specimens, not interfacial origins. Contact stresses (pressures) are clearly an important variable in wear testing and are not well-controlled in published work. Load-to-failure tests create damage not seen clinically due to excessively high contact stresses. Most contact stresses in the 119 tests examined were calculated to be between 1000 MPa and 5000 MPa, whereas clinical contact stresses at wear facets have been measured not to exceed 40 MPa.Conclusions. Our community can do a much better job of designing in vitro tests that more closely simulate clinical conditions, especially when contact is involved. Journals are encouraged to thoughtfully consider a ban on publishing papers using bond tests and load-to-failure methods that are seriously flawed and have no clinical relevance. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Intrinsic and extrinsic factors in the conservation of ants and their use as bioindicators.

Ant communities are sensitive to fragmentation responding through: extinction of specialist species compared with large habitats, invasion of generalist species, changes in community composition and richness of species. Because of these characteristics, this review aims at examining the main risks that ants have been facing to maintain their communities, as well as to report current conservation practices in Brazil and in the world.

Virulence factors in Escherichia coli strains isolated from pigs in the Ribeirao Preto region, State of Sao Paulo, Brazil.

Three-hundred faecal swabs were obtained from pigs with diarrhoea in farms located in different areas of the Ribeirao Preto region in the State of Sao Paulo. One-hundred Escherichia coli strains were isolated and tested for production of thermolabile (TL) and thermostable (STRa and STb) enterotoxins, and for the presence of colonization factors F4, F5 and F6. The strains were also tested for sensitivity to 14 antibiotics and chemotherapeutic agents. Twenty-four Escherichia coli strains produced enterotoxin STb, 5 produced LT and 3 produced STa. In the mannose-resistant haemagglutination reaction, one strain reacted positively with sheep, chicken, horse and human red blood cells and another reacted positively with guinea pig, sheep, chicken, horse and human red cells. However, both strains were negative for colonization factors F4, F5 and F6 when submitted to the slide agglutination test. All Escherichia coli strains were resistant to at least one antibiotic, the highest percentages being obtained for resistance to penicillin, tetracycline and cephalotin. In addition to the importance of the virulence factors normally encountered in enterotoxigenic Escherichia coli strains from pigs, the present results show the possible existence of new colonization factors other than F4, F5 and F6 participating in E. coli-induced pigs colibacillosis in the Ribeirao Preto region.

Prevalence of enamel white spots and risk factors in children up to 36 months old

The aim of this study was to determine the prevalence of enamel white spots and the quality of oral hygiene in children up to 36 months old, in municipalities with different fluoride levels in the water supply, analyzing the contribution of several variables. After approval of the Ethics Committee, the parents signed an informed consent form and were interviewed about their educational level, economic classification of the family, nursing habits, use of toothpaste, access to dental service and other information. The children were clinically examined using the same codes and criteria established by the WHO (World Health Organization) and ADA (American Dental Association). The data were processed and analyzed with the Epi-info software program, version 3.2, and Microsoft Excel. Fisher's exact test (p<0.05) was applied to assess the association among the variables. The enamel white spot prevalence was 30.8% and the age group, duration of the bedtime milk feeding habit, age of initial practice of oral hygiene and presence of caries lesions with cavitation were considered statistically significant with regard to enamel white spot prevalence (p < 0.05). No association was found between oral hygiene quality and the study variables. © 2009 Sociedade Brasileira de Pesquisa Odontológica.

Correlation between oral health perception and clinical factors in a Brazilian community

Objective: The aim of this study was to analyse associations between self-perception of oral health and relevant clinical, personal and socio-demographic factors in a Brazilian community. Material And Methods: Urban adults living in a city in southern Brazil were interviewerd and examined. Individuals with acute pain and who needed multiple extractions of teeth were excluded. Self-perception and the Oral Health Impact Profile (OHIP-14) were applied to measure the impact of oral conditions on the quality of life. Socio-demographic and clinical indicators were also analysed. Results: The clinical examination revealed a high dental caries experience (DMFT = 18.9) and a high prevalence of periodontal disease. Oral condition was considered normal by 42% of respondents. The variables associated with the OHIP-14 were: education, age, self-assessment, dental caries and the DMFT index. Conclusions: Self-perception of oral health was associated with OHIP-14 and the clinical indicators had low influence in the self-perception. Therefore, the development of educational initiatives and preventive strategies for the adult population is recommended. © BASCD 2011.