Studying metacognitive processes at the single neuron level

© 2014 Springer-Verlag Berlin Heidelberg. All rights reserved.Over the past few decades, strides have been made toward understanding how higher level cognitive processes are mediated by neuronal spiking activity. Neuronal correlates of functions such as attention, executive control, working memory, decision-making, and reward processing have all been elucidated, to an impressive level of detail, at the single cell and circuit levels

Invariant, super and quasi-martingale functions of a Markov process

We identify the linear space spanned by the real-valued excessive functions of a Markov process with the set of those functions which are quasimartingales when we compose them with the process. Applications to semi-Dirichlet forms are given. We provide a unifying result which clarifies the relations between harmonic, co-harmonic, invariant, co-invariant, martingale and co-martingale functions, showing that in the conservative case they are all the same. Finally, using the co-excessive functions, we present a two-step approach to the existence of invariant probability measures

Serological and molecular characterization of Cryptosporidium species from humans in Sokoto State, Nigeria

Cryptosporidium species are one of the most common causes of gastrointestinal infection in humans around the world. This study aimed at the characterization of Cryptosporidium species in humans using the 18S rRNA gene. Among the 368 human faecal samples screened using Cryptosporidium antigen Copro-ELISA kit, 61 (16.6%) were positive. The positive faecal samples were subjected to Nested PCR for the amplification of 830 bp fragments of small subunit (SSU) rRNA gene and followed by nucleotide sequencing. Out of the 61 copro-ELISA positive samples, 5 (8.2%) were PCR positive for Cryptosporidium species (3 (4.9%) of C. parvum and 2 (3.3%) of C. hominis). Two HIV patients were found to be harbouring C. parvum and C. hominis, so also as hypertensive and diarrheic patients harbouring C. parvum and C. hominis, respectively. Higher prevalence rates of Cryptosporidium was found in young children (11.1%), males (8.7%), loose faeces (42.9%) than older age groups (8.7%), females (7.9%) and well-formed (3.1%) or mucoid/pasty faeces (0%) based on the data gathered from the close-ended questionnaire also used on each human subject. This study was the first to report C. parvum and C. hominis infecting humans in Sokoto state, Northwestern Nigeria. It is suggested that a multi-locus study of Cryptosporidium species in developing countries would be necessary to determine the extent of transmission of Cryptosporidium in the populations

Bisphenol A Detection in Various Brands of Drinking Bottled Water in Riyadh, Saudi Arabia Using Gas Chromatography/Mass Spectrometer

Purpose: To assess whether bisphenol A contamination occurred in seven brands of bottled drinking water in Riyadh, Saudi Arabia.Methods: Liquid-liquid extraction (using dichloromethane) was used to analytically extract bisphenol A from drinking water bottles and a gas chromatograph-mass spectrometer was employed for its detection using a splitless capillary column and helium as the carrier gas.Results: The concentration of bisphenol A (BPA) was high in all the bottled water brands tested. The mean concentration of BPA of the bottled water stored indoors (4.03 ng/L) was significantly lower than that stored outdoors (7.5 ng/L).Conclusion: Our results show that significant amounts of BPA leached from bottle containers into the water. Long storage of bottled water under direct sunlight should be avoided to reduce the risk of human exposure to BPA

Genome Sequence of Erythromelalgia-Related Poxvirus Identifies it as an Ectromelia Virus Strain

Erythromelagia is a condition characterized by attacks of burning pain and inflammation in the extremeties. An epidemic form of this syndrome occurs in secondary students in rural China and a virus referred to as erythromelalgia-associated poxvirus (ERPV) was reported to have been recovered from throat swabs in 1987. Studies performed at the time suggested that ERPV belongs to the orthopoxvirus genus and has similarities with ectromelia virus, the causative agent of mousepox. We have determined the complete genome sequence of ERPV and demonstrated that it has 99.8% identity to the Naval strain of ectromelia virus and a slighly lower identity to the Moscow strain. Small DNA deletions in the Naval genome that are absent from ERPV may suggest that the sequenced strain of Naval was not the immediate progenitor of ERPV

Adherens junctions remain dynamic

One of the four principal categories of cell-cell junctions that hold together and shape distinct tissues and organs in vertebrates, adherens junctions (AJs) form cell-cell contacts that connect transmembrane proteins with cytoskeletal actin filaments to provide architectural strength, aid in morphogenesis, and help to maintain proper tissue homeostasis. The classical organization of AJs, consisting of transmembrane cadherins and cytoplasmically attached β-catenins and α-catenins assembled together into a multiprotein complex, was once thought obligatory to craft a robust and stable connection to actin-based cytoskeletal elements, but this architecture has since been challenged and questioned to exist. In a stimulating paper published in a recent issue of BMC Biology, Millán et al. provide convincing evidence that in confluent vascular endothelial cells a novel dynamic vascular endothelial (VE)-cadherin-based AJ type exists that interacts with and physically connects prominent bundles of tension-mediating actin filaments, stress fibers, between neighboring cells. Stress fibers were known previously to link to integrin-based focal adhesion complexes but not to cell-cell adhesion mediating AJs. These new findings, together with previous results support the concept that different AJ subtypes, sharing the same transmembrane cadherin types, can assemble in various configurations to either increase barrier function and promote physical cell-cell adhesion, or to lessen cell-cell adhesion and promote cell separation and migration

Experimental modulation of capsule size in Cryptococcus neoformans

Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the cryptococcal strain. A high CO(2) atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans

Down-regulation of miR-27a might inhibit proliferation and drug resistance of gastric cancer cells

<p>Abstract</p> <p>Aims</p> <p>Here we aimed to firstly investigate the role of miR-27a in proliferation and multidrug resistance of gastric cancer cells.</p> <p>Methods</p> <p>The role of miR-27a in gastric cancer cells was detected using MTT assay, soft agar assay, flow cytometry assay, nude mice assay, real-time PCR, western blot and reporter gene assay, etc.</p> <p>Results</p> <p>Down-regulation of miR-27a could inhibit porliferation of gastric cancer cells in vitro and in vivo. Down-regulation of miR-27a could also confer sensitivity of drugs on gastric cancer cells, and might increase accumulation and decrease releasing amount of adriamycin in gastric cancer cells. Down-regulation of miR-27a could significantly decrease the expression of P-glycoprotein and the transcriptional activity of cyclin D1, and up-regulate the expression of p21.</p> <p>Conclusions</p> <p>MiR-27a might play important roles in porliferation and drug resistance of gastric cancer. MiR-27a might be considered as a useful target for cancer therapy.</p

Augmentation of HIV-specific T cell function by immediate treatment of hyperacute HIV-1 infection

Sustained viremia after acute HIV infection is associated with profound CD4+ T cell loss and exhaustion of HIV-specific CD8+ T cell responses. To determine the impact of combination antiretroviral therapy (cART) on these processes, we examined the evolution of immune responses in acutely infected individuals initiating treatment before peak viremia. Immediate treatment of Fiebig stages I and II infection led to a rapid decline in viral load and diminished magnitude of HIV-specific (tetramer+) CD8+ T cell responses compared to untreated donors. There was a strong positive correlation between cumulative viral antigen exposure before full cART-induced suppression and immune responses measured by MHC class I tetramers, IFN-γ ELISPOT, and CD8+ T cell activation. HIV-specific CD8+ T responses of early treated individuals were characterized by increased CD127 and BCL-2 expression, greater in vitro IFN-γ secretion, and enhanced differentiation into effector memory (Tem) cells. Transcriptional analysis of tetramer+ CD8+ T cells from treated persons revealed reduced expression of genes associated with activation and apoptosis, with concurrent up-regulation of prosurvival genes including BCL-2, AXL, and SRC. Early treatment also resulted in robust HIV-specific CD4+ T cell responses compared to untreated HIV-infected individuals. Our data show that limiting acute viremia results in enhanced functionality of HIV-specific CD4+ and CD8+ T cells, preserving key antiviral properties of these cells

Differential adherence and expression of virulence traits by Candida albicans and Candida parapsilosis in mono- and dual-species cultures in artificial saliva

AIMS: To evaluate specific virulence factors of Candida albicans and Candida parapsilosis clinical oral isolates in mono- and dual-species culture in the presence of artificial saliva. METHODS AND RESULTS: Two of the strains used in this study were isolated from co-infection (C. albicans AM and C. parapsilosis AM2), and the other two were isolated from single infection (C. albicans AC and C. parapsilosis AD). The number of adhered yeast cells was measured and their enzymatic activity was determined simultaneously. In mono-species culture, C. parapsilosis strains adhered to a higher extent to the surface in comparison with the C. albicans strains. In dual-species culture, the C. parapsilosis strains adhered more in the presence of C. albicans AM. Interestingly, C. albicans AM and C. parapsilosis AD adhered to a higher extent when compared with all other co-cultures. In dual-species culture, the enzymatic activity of C. parapsilosis strains in the presence of C. albicans AC was higher than in the presence of C. albicans AM. CONCLUSIONS: The virulence factors of C. albicans and C. parapsilosis differ from strain to strain and are influenced by the presence of other species in culture. SIGNIFICANCE AND IMPACT OF THE STUDY: To understand the expression of virulence factors in Candida dual-species systems.This work was supported by Portuguese Foundation for Science and Technology (FCT) through the grant SFRH/BPD/20987/2004 attributed to Claudia Botelho