Detecção de Bacteroides fragilis enterotoxigênicos e não enterotoxigênicos de amostras fecais de crianças em São Paulo, Brasil

Non-enterotoxigenic bacteria of the Bacteroides fragilis group and enterotoxigenic B. fragilis were identified from children with and without aqueous acute diarrhea. In this study, 170 stool samples from 96 children with and 74 without diarrhea were analyzed. Enterotoxin production and the toxin gene detection were detected by cytotoxicity assay on HT-29/C1 cells and by PCR, respectively. B. fragilis species was prevalent in both groups and enterotoxigenic B. fragilis strains were isolated from two children with diarrhea. More studies are important to evaluate the role of each bacteria of the B. fragilis group, including enterotoxigenic strains play in the diarrheal processes in children.Bactérias não enterotoxigênicas do grupo Bacteroides fragilis e B. fragilis enterotoxigênicas foram isoladas e identificadas de crianças com e sem diarréia aguda aquosa. Neste estudo, 170 amostras fecais de 96 e 74 crianças, com e sem diarréia, respectivamente, foram analisadas. A produção de enterotoxina e a detecção do gene que media a produção da toxina foram determinadas por ensaios citotóxicos em células HT-29/C1 e por PCR, respectivamente. A espécie B. fragilis foi prevalente em ambos os grupos, e cepas de B. fragilis enterotoxigênicas foram isoladas de duas crianças com diarréia aquosa aguda. Maiores estudos são necessários para avaliar o papel de cada bactéria desse importante grupo bacteriano, incluindo-se o papel que as cepas enterotoxigênicas, desempenham no processo diarréico em crianças

Prevalência de periodontopatógenos em pacientes com doença periodontal e indivíduos sadios de São Paulo, SP, Brasil

A. actinomycetemcomitans, B. forsythus, P. gingivalis, C. rectus, E. corrodens, P. intermedia, F. nucleatum, and T. denticola were identified from subgingival plaque from 50 periodontal patients and 50 healthy subjects. PCR products from each species showed a specific band and could be used to identify periodontal organisms from clinical specimens. Identical negative or positive results between PCR and culture occurred in 66% (A. actinomycetemcomitans) to 93% (F. nucleatum) of the samples. PCR detection odds ratio values for A. actinomycetemcomitans, B. forsythus, C. rectus, E. corrodens, P. intermedia, and T. denticola were significantly associated with disease having a higher OR values for B. forsythus (2.97, 95% CI 1.88 - 4.70). Cultures showed that A. actinomycetemcomitans, B. forsythus and P. intermedia were associated with periodontitis, however, P. gingivalis, C. rectus, E. corrodens and F. nucleatum were not significantly associated with the disease.Cepas de A. actinomycetemcomitans, B. forsythus, P. gingivalis, C. rectus, E. corrodens, P. intermedia, F. nucleatum e T. denticola foram identificadas da placa subgengival de 50 pacientes com doença periodontal e 50 indivíduos sadios. Os produtos de PCR de cada espécie microbiana mostraram bandas específicas, favorecendo a identificação direta de bactérias periodontais de espécimes clínicos. Resultados negativos ou positivos idênticos entre PCR e a cultura ocorreram de 66% (A. actinomycetemcomitans) a 93% (F. nucleatum) das amostras. A detecção de A. actinomycetemcomitans, B. forsythus, C. rectus, E. corrodens, P. intermedia e T. denticola por PCR foi significativamente associada com a doença, mostrando valores altos de odds ratio (OR) para B. forsythus (2,97, 95% CI 1,88 - 4,70). Através da cultura foi observada a associação de A. actinomycetemcomitans, B. forsythus e P. intermedia com a periodontite, entretanto, P. gingivalis, C. rectus, E. corrodens e F. nucleatum não foram significativamente relacionados à doença

Diversidade genética de Fusobacterium nucleatum orais isolados de pacientes com diferentes condições clínicas

The genetic diversity of 23 oral Fusobacterium nucleatum isolated from 15 periodontal patients, eight from seven healthy subjects, nine from nine AIDS patients and two from two Cebus apella monkeys were analyzed. EcoRI restricted the bacterial DNA and 28 ribotypes grouped from A to J groups were obtained. Isolates formed 24 ribotypes which were contained into A, B, C, D, E and F groups, and three reference strains and two clinical isolates of A. actinomycetemcomitans, and E. coli CDC formed four different ribotypes into the G, H, I and J groups. Moreover, from nine F. nucleatum from AIDS patients, six were ribotyped as group C and three as group D. By using ribotyping we distinguished F. nucleatum recovered from different sources. It is possible that isolates from AIDS patients may contain some phenotypic or genotypic factor did not observed in this study.Neste estudo foi avaliada a diversidade genética de 23 amostras de Fusobacterium nucleatum isoladas da cavidade bucal de 15 pacientes com doença periodontal, de oito cepas isoladas de sete indivíduos sadios, de nove isoladas de nove pacientes com AIDS e de duas isoladas de dois macacos Cebus apella. Pela ação da enzima EcoRI sobre o DNA bacteriano foram reconhecidos 28 ribotipos agrupados de A a J. Os isolados testados formaram 24 ribotipos os quais foram contidos nos grupos A, B, C, D, E e F, e as três cepas de referência e dois isolados clínicos de A. actinomycetemcomitans e E. coli CDC formaram quatro diferentes ribotipos contidos nos grupos G, H, I e J. Em adição, as nove cepas de F. nucleatum isoladas de pacientes com AIDS, seis pertenciam ao grupo C e três ao grupo D. Usando-se a ribotipagem foi possível distinguir F. nucleatum isolados de diferentes origens

Stellar Properties of z ~ 8 Galaxies in the Reionization Lensing Cluster Survey

Measurements of stellar properties of galaxies when the universe was less than one billion years old yield some of the only observational constraints of the onset of star formation. We present here the inclusion of \textit{Spitzer}/IRAC imaging in the spectral energy distribution fitting of the seven highest-redshift galaxy candidates selected from the \emph{Hubble Space Telescope} imaging of the Reionization Lensing Cluster Survey (RELICS). We find that for 6/8 \textit{HST}-selected $z\gtrsim8$ sources, the $z\gtrsim8$ solutions are still strongly preferred over $z\sim$1-2 solutions after the inclusion of \textit{Spitzer} fluxes, and two prefer a $z\sim 7$ solution, which we defer to a later analysis. We find a wide range of intrinsic stellar masses ($5\times10^6 M_{\odot}$ -- $4\times10^9$ $M_{\odot}$), star formation rates (0.2-14 $M_{\odot}\rm yr^{-1}$), and ages (30-600 Myr) among our sample. Of particular interest is Abell1763-1434, which shows evidence of an evolved stellar population at $z\sim8$, implying its first generation of star formation occurred just $< 100$ Myr after the Big Bang. SPT0615-JD, a spatially resolved $z\sim10$ candidate, remains at its high redshift, supported by deep \textit{Spitzer}/IRAC data, and also shows some evidence for an evolved stellar population. Even with the lensed, bright apparent magnitudes of these $z \gtrsim 8$ candidates (H = 26.1-27.8 AB mag), only the \textit{James Webb Space Telescope} will be able further confirm the presence of evolved stellar populations early in the universe.Comment: 8 pages, 3 figures, 2 table

Apoptotic microtubules delimit an active caspase free area in the cellular cortex during the execution phase of apoptosis

Apoptotic microtubule network (AMN) is organized during apoptosis, forming a cortical structure beneath plasma membrane, which has an important role in preserving cell morphology and plasma membrane permeability. The aim of this study was to examine the role of AMN in maintaining plasma membrane integrity during the execution phase of apoptosis. We demonstrated in camptothecin-induced apoptosis in H460 cells that AMN delimits an active caspase free area beneath plasma membrane that permits the preservation of cellular cortex and transmembrane proteins. AMN depolymerization in apoptotic cells by a short exposure to colchicine allowed active caspases to reach the cellular cortex and cleave many key proteins involved in plasma membrane structural support, cell adhesion and ionic homeostasis. Cleavage of cellular cortex and plasma membrane proteins, such as a-spectrin, paxilin, focal adhesion kinase (FAK), E-cadherin and integrin subunit b4 was associated with cell collapse and cell detachment. Otherwise, cleavage-mediated inactivation of calcium ATPase pump (PMCA-4) and Naþ/Ca2þ exchanger (NCX) involved in cell calcium extrusion resulted in calcium overload. Furthermore, cleavage of Naþ/Kþ pump subunit b was associated with altered sodium homeostasis. Cleavage of cell cortex and plasma membrane proteins in apoptotic cells after AMN depolymerization increased plasma permeability, ionic imbalance and bioenergetic collapse, leading apoptotic cells to secondary necrosis. The essential role of caspase-mediated cleavage in this process was demonstrated because the concomitant addition of colchicine that induces AMN depolymerization and the pan-caspase inhibitor z-VAD avoided the cleavage of cortical and plasma membrane proteins and prevented apoptotic cells to undergo secondary necrosis. Furthermore, the presence of AMN was also critical for proper phosphatidylserine externalization and apoptotic cell clearance by macrophages. These results indicate that AMN is essential to preserve an active caspase free area in the cellular cortex of apoptotic cells that allows plasma membrane integrity during the execution phase of apoptosis

Evidence of a Non-universal Stellar Initial Mass Function. Insights from HST Optical Imaging of Six Ultra-faint Dwarf Milky Way Satellites

Using deep observations obtained with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST), we demonstrate that the sub-solar stellar initial mass function (IMF) of six ultra-faint dwarf Milky Way satellites (UFDs) is more bottom light than the IMF of the Milky Way disk. Our data have a lower-mass limit of ~0.45 M_⊙, while the upper limit is ~0.8 M_⊙, set by the turnoff mass of these old, metal-poor systems. If formulated as a single power law, we obtain a shallower IMF slope than the Salpeter value of −2.3, ranging from −1.01 for Leo IV to −1.87 for Boötes I. The significance of these deviations depends on the galaxy and is typically 95% or more. When modeled as a log-normal, the IMF fit results in a higher peak mass than in the Milky Way disk, but a Milky Way disk value for the characteristic system mass (~0.22 M_⊙) is excluded at only 68% significance, and only for some UFDs in the sample. We find that the IMF slope correlates well with the galaxy mean metallicity, and to a lesser degree, with the velocity dispersion and the total mass. The strength of the observed correlations is limited by shot noise in the number of observed stars, but future space-based missions like the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope ( WFIRST) will enhance both the number of dwarf Milky Way satellites that can be studied in such detail and the observation depth for individual galaxies