Association between polyclonal B cell activation and the presence of autoantibodies in mice infected with Yersinia enterocolitica O:3

Eight-week old conventional female Swiss mice were inoculated intravenously with Yersinia enterocolitica O:3. A second group of normal mice was used as control. Five mice from each group were bled by heart puncture and their spleens were removed for spleen cell collection on the 3rd, 5th, 7th, 10th, 14th and 21st day after infection. Immunoglobulin-secreting spleen cells were detected by the isotype-specific protein A plaque assay. Total immunoglobulin levels were determined in mouse serum by single radial immunodiffusion and the presence of autoantibodies was determined by ELISA. We observed a marked increase in the total number of cells secreting immunoglobulins of all isotypes as early as on the 3rd day post-infection and the peak of secretion occurred on the 7th day. At the peak of the immunoglobulin response, the total number of secreting cells was 19 times higher than that of control mice and most immunoglobulin-secreting cells were of the IgG2a isotype. On the 10th day post-infection, total serum immunoglobul in values were 2 times higher in infected animals when compared to the control group, and continued at this level up to the 21st day post-infection. Serum absorption with viable Y. enterocolitica cells had little effect on antibody levels detected by single radial immunodiffusion. Analysis of serum autoantibody levels revealed that Y. enterocolitica infection induced an increase of anti-myosin and anti-myelin immunoglobulins. The sera did not react with collagen. The present study demonstrates that Y. enterocolitica O:3 infection induces polyclonal activation of murine B cells which is correlated with the activation of some autoreactive lymphocyte clones.

Microbiological quality of ice used to refrigerate foods

Ice used for human consumption or to refrigerate foods can be contaminated with pathogenic microorganisms and may become a vehicle for human infection. To evaluate the microbiological content of commercial ice and ice used to refrigerate fish and seafood, 60 ice samples collected at six different retail points in the city of Araraquara, SP, Brazil, were studied. The following parameters were determined: total plate counts (37° C and 4° C), most probable number (MPN) for total coliforms, fecal coliforms and Escherichia coli, presence of Salmonella spp., Shigella spp., Yersinia spp., E. coli, Vibrio cholerae and Aeromonas spp.. Results suggested poor hygienic conditions of ice production due to the presence of indicator micro-organisms. Fifty strains of E. coli of different serotypes, as well as one Y. enterocolitica biotype 1, serogroup 0:5, 27 and phage type Xz (Ye 1/05,27/Xz) and one Salmonella Enteritidis phage type 1 (PT1) were isolated. Aeromonas spp., Shigella spp. and V. cholerae were not detected. The presence of high numbers of coliforms, heterotrophic indicator micro-organisms and pathogenic strains suggested that commercial ice and ice used to refrigerate fish and seafood may rep resent a potential hazard to the consumer in our community. © 2002 Elsevier Science Ltd. All rights reserved.

Frequency upconversion in rare-earth doped fluoroindate glasses

We present recent results on frequency upconversion (UPC) obtained in fluoroindate glasses (FIG) doped with Ho3+, Tm3+ and Nd3+ ions and codoped with Pr3+/Nd3+ and Yb3+/Tb3+ ions. The results for the Ho3+-doped samples show strong evidence of energy transfer (ET) between Ho3+ ions resonantly excited at 640 nm. The origin of the blue-green upconverted fluorescence observed was identified and the dynamics of the signals revealed the pathways involved in the UPC process. In the case of Tm3+-doped FIG, the samples were resonantly excited at 650 nm and the main mechanism that contributes for the red-to-blue upconversion is excited-state absorption (ESA). The FIG samples codoped with Pr3+/Nd3+ were excited at 588 nm in resonance with transitions starting from the ground state of the Nd 3+ and the Pr3+ ions. It was observed that the presence of Nd3+ ions enhanced the Pr3+ emission at 480 nm by two orders of magnitude. Multiphonon (MP)-assisted upconversion is also discussed for Nd3+-doped FIG pumped at 866 nm. Emission at 750 nm with a peculiar linear dependence with the laser intensity was observed and explained. A rate-equation model that includes MP absorption via thermally coupled electronic excited states of Nd3+ was developed and describes well the experimental results. The role played by effective phonon modes is clearly demonstrated. MP-assisted UPC process was also studied in Yb3+/ Tb3+-codoped FIG samples excited at 1064 nm, which is off-resonance with electronic transitions starting from the ground state. It was determined that the mechanism leading to Tb3+ emission in the blue is due to ET from a pair of excited Yb3+ ions followed by ESA in the Tb 3+ ions. © 2002 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS.

Niche-specific association of Aeromonas ribotypes from human and environmental origin

A total of 88 Aeromonas isolates from distinct locations and sources (39 from extraintestinal infections, 31 from diarrhoeic, ten from non-diarrhoeic faeces, all human, and eight from fresh water) were subjected to phenospecies identification, serotyping, ribotyping and detection of some virulence markers. The strains belonged to four different phenospecies marked by 19 O serogroups and 38 ribotypes. No strong correlation between these parameters was found, and no group, as defined by the typing methods, could be characterized with a particular set of virulence markers. There was a clear association of ribotypes with the source of the strains. Cluster analysis allowed the identification of a complex of ribotypes belonging to distinct but related sources, including clinical and environmental isolates. These results suggest that ribotyping may be an epidemiological tool suitable for the study of Aeromonas infections.

Importância de Yersinia enterocolitica em microbiologia médica

Y. enterocolitica is a human invasive enteropathogen which causes a number of intestinal and extraintestinal clinical symptoms of various degrees of severity, ranging from mild gastroenteritis to mesenteric lymphadenitis, which mimics appendicitis and in rare cases can evolve to septicemia. Infection by Y. enterocolitica can also lead to post-infection immunological sequelae including arthritis, erythema nodosum and glomerulonephritis. Pathogenic Y. enterocolitica strains have traditionally been linked to specific biotypes and serogroups and associated to a variety of phenotypic characteristics related to virulence. Molecular genetics studies have pointed to the importance of the pYV virulence plasmid, which encodes various virulence genes, as well that of specific chromosomal virulence genes, in determining the pathogenesis of this bacterium. Intestinal infections by Y. enterocolitica are mostly self-limiting and usually do not need an antibiotic treatment. The occurrence of this microorganism is not as frequently described in Brazil as it is in other countries, such as Japan, USA and many European countries. This review focuses on the general characteristics, pathogenesis, clinical symptoms, virulence characteristics, treatment and antibiotic susceptibility of Yersinia enterocolitica strains isolated in Brazil and around the world.

Invasin of Yersinia pseudotuberculosis is not a polyclonal activator of mouse B lymphocytes

It is known that the invasin molecule of Yersinia pseudotuberculosis stimulates human peripheral B cells in vitro. In this work we evaluated the in vivo role of invasin as polyclonal activator of B lymphocytes in the mouse experimental model, by comparing strains of Y. pseudotuberculosis expressing invasin and isogenic inv mutants. Swiss mice were infected intravenously with two strains expressing invasin (YpIII pIB1 and an isogenic virulence plasmid-cured strain, YpIII) and with two invasin mutant strains (Yp100 pIB1 and Yp100, plasmid-cured). Spleen cells were sampled on days 7, 14, 21 and 28 after infection. Immunoglobulin (Ig)-secreting spleen cells were detected by protein A plaque assay and specific antibodies were detected in sera by ELISA. The virulent strain YPIII pIB1 (wild type) did not provoke polyclonal activation of B lymphocytes in vivo. In general, fewer Ig-secreting spleen cells of all isotypes were found in the infected animals than in the control animals. Specific IgG antibodies were detected in the sera of animals infected with all strains. The peak response occurred on the 21 st day post-infection, and the Yp100 strain provoked the highest level of these antibodies. We concluded that invasin is not a polyclonal activator of murine B cells.

Antimony glasses with large nonlinear refractive indices, small two-photon absorption coefficients and ultrafast response at telecom wavelengths

Nonlinear (NL) optical properties of antimony oxide based glasses (AG) were characterized for excitation wavelengths from 800 to 1600 m. The NL refractive indices, n2, and the two-photon absorption (TPA) coefficient, β, have been evaluated using the Z-scan technique. Values of n2≈ 10-15 - 10-14 cm2/W of electronic origin were measured and negligible TPA coefficients (β < 0.003 cm/GW) were determined. The response time of the nonlinearity is faster than 100 fs as determined using the Kerr shutter technique. The figure-of-merit usually considered for all-optical switching, T = 2βλ/n2 , indicates that AG are very good materials for ultrafast switches at telecom wavelengths. © 2007 IEEE.

Histological evaluation of the bone repair using mineral trioxide aggregate combined to a material carrier

The aim of this study was to present a possible carrier for MTA, monoolein gel, with the objective to maintain this material in the place that was inserted and verify if this procedure is able to optimize its action. The data were evaluated by histomorphometric method and submitted to statistical analysis. The histological responses observed in this study indicate that the MTA is a reliable material and should be considered effective in bone periapical defects and the monoolein gel was capable to maintain the MTA in situ.

Plesiomonas shigelloides: Um enteropatógeno emergente?

Plesiomonas shigelloides is a Gram-negative rod-shaped bacterium, of the family Enterobacteriaceae, which has been isolated from freshwater and salt water, freshwater fish, shellfish and many species of animals. Most human P. shigelloides infections are suspected to be waterborne. The organism can be found in untreated water used as drinking water, in recreational water, or in water used to rinse food that is consumed without cooking or heating. The ingestion of P. shigelloides does not always cause illness in the host animal, and the organism may be present temporarily as a transient, noninfectious member of the intestinal flora. It has been isolated from the stools of patients with diarrhea,but it is also sometimes isolated from healthy individuals. P. shigelloides has been implicated in gastroenteritis, usually a self-limiting disease characterized by fever, chills, abdominal pain, nausea, diarrhea or vomiting; in severe cases the diarrhea may be yellowish-green, foamy and tinged with blood. The bacteria may also cause extra-intestinal infection. Furthermore, it can produce toxins and may be invasive. The evidence in favor of considering P. shigelloides as an enteropathogen is not totally convincing. Although it has been isolated from patients with diarrhea and incriminated in some outbreaks involving contaminated water and food, it was not possible, in many P. shigelloides samples associated with gastrointestinal infections, to identify a definite mechanism of virulence.

Cursos de geologia: expansão, interiorização e consolidação do ensino de geologia no brasil

A short time after the creation of the first Geology courses in Brazil (in 1957 with the pioneers in the University of São Paulo and in the Federal Universities of Ouro Preto, Pernambuco and Rio Grande do Sul, and then in the following year in the Federal Universities of Bahia and Rio de Janeiro), there arose other initiatives that spread almost twenty Geology courses throughout Brazil. In addition to expanding the Geology teaching in the South, Southeast and Northeast regions, these initiatives succeeded in allowing access to geological education for the population in the North and Central-west of Brazil. In the 1960s, the courses in the Federal University of Para in Belém (1964), University of Brasilia (1965) and São Paulo State University in Rio Claro (1969) were implanted. In the following decade, the courses in the Federal Rural University of Rio de Janeiro in Seropédica (1970), the Federal University of Ceará in Fortaleza (1970), the University of Rio dos Sinos in São Leopoldo (1973), the Federal University of Paraná in Curitiba (1973), the Federal University of Minas Gerais in Belo Horizonte (1973), the Federal University of Amazonas in Manaus (1976), the Federal University of Mato Grosso in Cuiabá (1976), the Federal University of Rio Grande do Norte in Natal (1976), and the State University of Rio de Janeiro in Rio de Janeiro (1977) were all created. At the close of the twentieth century, the course was implanted in the State University of Campinas (1998). Now, at the beginning of the twenty-first century, new Geology courses are being implanted, accentuating the movement inland of Geology teaching in Brazil. The Federal University of Pará began a new course in its campus in Marabá in the south-east of Pará and the Federal University of Bahia implanted a new course in its campus in Barreiras in the west of Bahia. Finally, the Federal Universities of Sergipe, Espírito Santo and Roraima commenced Geology courses in Aracaju, Alegre and Boa Vista, respectively. This chapter will present the synthesis of the Geology courses which, over the last decades of the twentieth century, contributed to the expansion of Geology teaching in the country, taking it to every region and giving opportunities to a large number of Brazilian citizens to realize their dreams and tread the paths of their professional vocation.

Oropharyngeal dysphagia identification using wavelets and optimum path forest

The swallowing disturbers are defined as oropharyngeal dysphagia when present specifies signals and symptoms that are characterized for alterations in any phases of swallowing. Early diagnosis is crucial for the prognosis of patients with dysphagia and the potential to diagnose dysphagia in a noninvasive manner by assessing the sounds of swallowing is a highly attractive option for the dysphagia clinician. This study proposes a new framework for oropharyngeal dysphagia identification, having two main contributions: a new set of features extract from swallowing signal by discrete wavelet transform and the dysphagia classification by a novel pattern classifier called OPF. We also employed the well known SVM algorithm in the dysphagia identification task, for comparison purposes. We performed the experiments in two sub-signals: the first was the moment of the maximal peak (MP) of the signal and the second is the swallowing apnea period (SAP). The OPF final accuracy obtained were 85.2% and 80.2% for the analyzed signals MP and SAP, respectively, outperforming the SVM results. ©2008 IEEE.