1,618 research outputs found

    Siglec-F is a novel intestinal M cell marker

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    Intestinal microfold (M) cells are epithelial cells primarily present on Peyer's patches (PPs) in the small intestine. The ability of M cells to shuttle antigens into the PP for appropriate immune responses makes M cells a target for next-generation oral vaccine delivery. In this regard, discovery of M cell specific receptors are of great interest, which could act as molecular tags for targeted delivery of cargo to M cells. Here, using a monoclonal antibody we generated to the Sialic acid-binding immunoglobulin-like lectin F (Siglec-F), we show that Siglec-F is expressed on mouse M cells in the small intestine. Immunohistochemical analysis of the PP tissue sections shows that Siglec-F is expressed on the surface of the M cell membrane exposed to the intestinal lumen. Anti-Siglec-F antibody injected into the mouse small intestine bound to M-cells, demonstrating the potential to target M cells via Siglec-F

    Collective dynamics of two-mode stochastic oscillators

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    We study a system of two-mode stochastic oscillators coupled through their collective output. As a function of a relevant parameter four qualitatively distinct regimes of collective behavior are observed. In an extended region of the parameter space the periodicity of the collective output is enhanced by the considered coupling. This system can be used as a new model to describe synchronization-like phenomena in systems of units with two or more oscillation modes. The model can also explain how periodic dynamics can be generated by coupling largely stochastic units. Similar systems could be responsible for the emergence of rhythmic behavior in complex biological or sociological systems.Comment: 4 pages, RevTex, 5 figure

    Uso de meio seletivo para identificação de cepas de Burkholderia cepacia em amostras de trato respiratório de pacientes portadores de fibrose cística

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    Burkholderia cepacia colonizes cystic fibrosis (CF) patients. We evaluated the impact of the use of a selective medium in the rate of B. cepacia recovery from respiratory samples of CF patients. During a 6-month period, respiratory samples were collected from 106 CF patients and cultivated on selective media including a B. cepacia selective medium. Confirmation of the identity of B. cepacia isolates was carried out by species specific PCR and determination of genomovar status performed by a sequential PCR approach. Results of B. cepacia isolation during this period were compared to the preceding two years, when the sample processing was identical except for the lack of the B. cepacia selective medium. B. cepacia was isolated in 11/257 (4.2%) of the samples using the selective medium, in contrast with the preceding two years, when it was isolated in 6/1029 samples (0.58%), p < 0.0001. Identity of all 11 isolates was confirmed by PCR and genomovar determination was accomplished in all but one isolate. These results suggest that the use of a selective medium increases recovery rate of B. cepacia from respiratory samples.A Burkholderia cepacia coloniza os pacientes portadores de fibrose cística (FC). Avaliamos o impacto do uso de um meio seletivo no isolamento de B. cepacia em amostras de secreção respiratória de pacientes portadores de FC. Durante um período de 6 meses, amostras de trato respiratório foram colhidas de 106 pacientes com FC e cultivadas em meios seletivos incluindo um meio para isolamento de B. cepacia. A identidade das cepas de B. cepacia foi confirmada através de PCR espécie específica e a determinação do genomovar ou subespécie realizada através de reações seqüenciais de PCR. Os resultados de isolamento de B. cepacia durante este período foram comparados com os dois anos precedentes, quando o processamento das amostras era idêntico, exceto pela utilização do meio seletivo para B. cepacia. B. cepacia foi isolada em 11/257 (4,2%) amostras usando o meio seletivo, e em apenas 6/1029 (0,58%) nos dois anos precedentes (p < 0,0001). A identidade destas 11 cepas foi confirmada e a determinação do genomovar obtida em 10/11. Estes resultados sugerem que o uso do meio seletivo aumenta a freqüência de isolamento de B. cepacia em amostras de trato respiratório de pacientes portadores de FC

    Apolipoprotein E4 Frequencies in a Japanese Population with Alzheimer's Disease and Dementia with Lewy Bodies

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    BACKGROUND: The apolipoprotein E (APOE) ε4 allele has been reported to be a risk factor for Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Previous neuropathological studies have demonstrated similar frequencies of the APOE ε4 allele in AD and DLB. However, the few ante-mortem studies on APOE allele frequencies in DLB have shown lower frequencies than post-mortem studies. One reason for this may be inaccuracy of diagnosis. We examined APOE genotypes in subjects with AD, DLB, and a control group using the latest diagnostic criteria and MRI, SPECT, and MIBG myocardial scintigraphy. METHODS: The subjects of this study consisted of 145 patients with probable AD, 50 subjects with probable DLB, and a control group. AD subjects were divided into two groups based on age of onset: early onset AD (EOAD) and late onset AD (LOAD). All subjects had characteristic features on MRI, SPECT, and/or myocardial scintigraphy. RESULTS: The rate of APOE4 carrier status was 18.3% and the frequency of the ε4 allele was 9.7% in controls. The rate of APOE4 carrier status and the frequency of the ε4 allele were 47% and 27% for LOAD, 50% and 31% for EOAD, and 42% and 31% for DLB, respectively. CONCLUSION: The APOE4 genotypes in this study are consistent with previous neuropathological studies suggesting accurate diagnosis of AD and DLB. APOE4 genotypes were similar in AD and DLB, giving further evidence that the ε4 allele is a risk factor for both disorders

    Rhinovirus C and Respiratory Exacerbations in Children with Cystic Fibrosis

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    To investigate a possible role for human rhinovirus C in respiratory exacerbations of children with cystic fibrosis, we conducted microbiologic testing on respiratory specimens from 103 such patients in São Paulo, Brazil, during 2006–2007. A significant association was found between the presence of human rhinovirus C and respiratory exacerbations

    Cellularly-Driven Differences in Network Synchronization Propensity Are Differentially Modulated by Firing Frequency

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    Spatiotemporal pattern formation in neuronal networks depends on the interplay between cellular and network synchronization properties. The neuronal phase response curve (PRC) is an experimentally obtainable measure that characterizes the cellular response to small perturbations, and can serve as an indicator of cellular propensity for synchronization. Two broad classes of PRCs have been identified for neurons: Type I, in which small excitatory perturbations induce only advances in firing, and Type II, in which small excitatory perturbations can induce both advances and delays in firing. Interestingly, neuronal PRCs are usually attenuated with increased spiking frequency, and Type II PRCs typically exhibit a greater attenuation of the phase delay region than of the phase advance region. We found that this phenomenon arises from an interplay between the time constants of active ionic currents and the interspike interval. As a result, excitatory networks consisting of neurons with Type I PRCs responded very differently to frequency modulation compared to excitatory networks composed of neurons with Type II PRCs. Specifically, increased frequency induced a sharp decrease in synchrony of networks of Type II neurons, while frequency increases only minimally affected synchrony in networks of Type I neurons. These results are demonstrated in networks in which both types of neurons were modeled generically with the Morris-Lecar model, as well as in networks consisting of Hodgkin-Huxley-based model cortical pyramidal cells in which simulated effects of acetylcholine changed PRC type. These results are robust to different network structures, synaptic strengths and modes of driving neuronal activity, and they indicate that Type I and Type II excitatory networks may display two distinct modes of processing information

    Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.

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    Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells
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