Local and global processing. Observations from a remote culture

In Experiment 1, a normal adult population drawn from a remote culture (Himba) in northern Namibia made similarity matches to [Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353–383] hierarchical figures. The Himba showed a local bias stronger than that has been previously observed in any other non-clinical human population. However, in Experiment 2, their recognition of normal or distorted (“Thatcherized”) faces did not appear to have been affected by their attention to detail as has been suggested for autistic populations. The data are consistent with a cultural/experiential origin for population differences in local processing and suggest that attention to the local and global properties of stimuli may differ for hierarchical figures and faces

Cultural Differences in Perception: Observations from a Remote Culture

Perceptual similarity was examined in a remote culture (Himba) and compared to that of Western observers. Similarity was assessed in a relative size judgement task and in an odd-one-out detection task. Thus, we examined the effects of culture on what might be considered low-level visual abilities. For both tasks, we found that performance was affected by stimuli that were culturally relevant to the tasks. In Experiment 1, we showed that the use of cow stimuli instead of the standard circles increased illusory strength for the Himba. In Experiment 2, only the Himba showed more accurate detection based on category differences in the displays. It is argued that that Categorical Perception in Experiment 2, based on its presumed Whorfian origins, was the more reliable procedure for examining the effects of culture on perception

Monitoring Antigen Processing for MHC Presentation via Macroautophagy

Macroautophagy has recently emerged as an important catabolic process involved not only in innate immunity but also in adaptive immunity. Initially described to deliver intracellular antigens to MHC class II loading compartments, its molecular machinery has now also been described to impact the delivery of extracellular antigens to MHC class II loading compartments through the noncanonical use of the macroautophagy machinery during LC3-associated phagocytosis (LAP). Therefore, in pathological situations (viral or bacterial infections, tumorigenesis) the pathway might be involved in shaping CD4$^{+}$ T cell responses.In this chapter we describe three basic experiments for the monitoring and manipulation of macroautophagic antigen processing toward MHC class II presentation through the canonical pathway. Firstly, we will discuss how to monitor autophagic flux and autophagosome fusion with MHC class II loading compartments. Secondly, we will show how to target proteins to autophagosomes in order to monitor macroautophagy dependent antigen processing via their enhanced presentation on MHC class II molecules to CD4$^{+}$ T cells. And finally, we will describe how macroautophagy can be silenced in antigen presenting cells, like human monocyte-derived dendritic cells (DCs)

Colour categories are reflected in sensory stages of colour perception when stimulus issues are resolved

Debate exists about the time course of the effect of colour categories on visual processing. We investigated the effect of colour categories for two groups who differed in whether they categorised a blue-green boundary colour as the same- or different-category to a reliably-named blue colour and a reliably-named green colour. Colour differences were equated in just-noticeable differences to be equally discriminable. We analysed event-related potentials for these colours elicited on a passive visual oddball task and investigated the time course of categorical effects on colour processing. Support for category effects was found 100 ms after stimulus onset, and over frontal sites around 250 ms, suggesting that colour naming affects both early sensory and later stages of chromatic processing

Impact of HIV on Cell Survival and Antiviral Activity of Plasmacytoid Dendritic Cells

Plasmacytoid dendritic cells (pDCs) are important mediators of innate immunity that act mainly through secretion of interferon (IFN)-α. Previous studies have found that these cells can suppress HIV in vitro; additionally, pDCs have been shown to be severely reduced in the peripheral blood of HIV-infected individuals. In the present study, we sought to determine the ability of pDCs to directly suppress viral replication ex vivo and to delineate the potential mechanisms whereby pDCs are depleted in HIV-infected individuals. We demonstrate that activated pDCs strongly suppress HIV replication in autologous CD4(+) T cells via a mechanism involving IFN-α as well as other antiviral factors. Of note, unstimulated pDCs from infected individuals who maintain low levels of plasma viremia without antiretroviral therapy were able to suppress HIV ex vivo via a mechanism requiring cell-to-cell contact. Our data also demonstrate that death of pDCs by both apoptosis and necrosis is induced by fusion of HIV with pDCs. Taken together, our data suggest that pDCs play an important role in the control of HIV replication and that high levels of viral replication in vivo are associated with pDC cell death via apoptosis and necrosis. Elucidation of the mechanism by which pDCs suppress HIV replication in vivo may have clinically relevant implications for future therapeutic strategies

CD4CD8αα Lymphocytes, A Novel Human Regulatory T Cell Subset Induced by Colonic Bacteria and Deficient in Patients with Inflammatory Bowel Disease

It has become evident that bacteria in our gut affect health and disease, but less is known about how they do this. Recent studies in mice showed that gut Clostridium bacteria and their metabolites can activate regulatory T cells (Treg) that in turn mediate tolerance to signals that would ordinarily cause inflammation. In this study we identify a subset of human T lymphocytes, designated CD4CD8αα T cells that are present in the surface lining of the colon and in the blood. We demonstrate Treg activity and show these cells to be activated by microbiota; we identify F. prausnitzii, a core Clostridium strain of the human gut microbiota, as a major inducer of these Treg cells. Interestingly, there are fewer F. prausnitzii in individuals suffering from inflammatory bowel disease (IBD), and accordingly the CD4CD8αα T cells are decreased in the blood and gut of patients with IBD. We argue that CD4CD8αα colonic Treg probably help control or prevent IBD. These data open the road to new diagnostic and therapeutic strategies for the management of IBD and provide new tools to address the impact of the intestinal microbiota on the human immune system

Connected by sea, disconnected by tuna? Challenges to regionalism in the Southwest Indian Ocean

Madagascar, Mauritius and Seychelles are at the center of industrial tuna extraction in the Southwest Indian Ocean (SWIO). In this paper, we show that, while a discourse of regionalism between the three islands is prominent, the possibilities of regionalism face deep challenges in relation to the tuna industry. This is due to three factors. First, local perceptions, especially amongst those working in and on the tuna industry, are in disconnection with an ‘Indianoceania’ vision. Second, the geopolitics between coastal states and distant water fishing nations create various entanglements including through fishing access revenue and foreign aid. Finally, the materiality of tuna can at times create competition as countries seek to individually maximize benefits from the industry. We argue that the active reinforcement of regional identity and collaboration around this resource is necessary to sustain local benefits into the future

Combined antiviral activity of interferon-α and RNA interference directed against hepatitis C without affecting vector delivery and gene silencing

The current standard interferon-alpha (IFN-α)-based therapy for chronic hepatitis C virus (HCV) infection is only effective in approximately half of the patients, prompting the need for alternative treatments. RNA interference (RNAi) represents novel approach to combat HCV by sequence-specific targeting of viral or host factors involved in infection. Monotherapy of RNAi, however, may lead to therapeutic resistance by mutational escape of the virus. Here, we proposed that combining lentiviral vector-mediated RNAi and IFN-α could be more effective and avoid therapeutic resistance. In this study, we found that IFN-α treatment did not interfere with RNAi-mediated gene silencing. RNAi and IFN-α act independently on HCV replication showing combined antiviral activity when used simultaneously or sequentially. Transduction of mouse hepatocytes in vivo and in vitro was not effected by IFN-α treatment. In conclusion, RNAi and IFN-α can be effectively combined without cross-interference and may represent a promising combinational strategy for the treatment of hepatitis C

Human Neonatal Dendritic Cells Are Competent in MHC Class I Antigen Processing and Presentation

Neonates are clearly more susceptible to severe disease following infection with a variety of pathogens than are adults. However, the causes for this are unclear and are often attributed to immunological immaturity. While several aspects of immunity differ between adults and neonates, the capacity of dendritic cells in neonates to process and present antigen to CD8+ T cells remains to be addressed. We used human CD8+ T cell clones to compare the ability of neonatal and adult monocyte-derived dendritic cells to present or process and present antigen using the MHC class I pathway. Specifically, we assessed the ability of dendritic cells to present antigenic peptide, present an HLA-E–restricted antigen, process and present an MHC class I-restricted antigen through the classical MHC class I pathway, and cross present cell-associated antigen via MHC class I. We found no defect in neonatal dendritic cells to perform any of these processing and presentation functions and conclude that the MHC class I antigen processing and presentation pathway is functional in neonatal dendritic cells and hence may not account for the diminished control of pathogens

Plasmacytoid Dendritic Cells Capture and Cross-Present Viral Antigens from Influenza-Virus Exposed Cells

Among the different subsets of dendritic cells (DC), plasmacytoid dendritic cells (PDC) play a unique role in secreting large amounts of type I interferons upon viral stimulation, but their efficiency as antigen-presenting cells has not been completely characterized. We show here, by flow cytometry, with human primary blood PDC and with a PDC cell line, that PDC display poor endocytic capacity for soluble or cellular antigens when compared to monocyte-derived myeloid DC. However, immature PDC efficiently take up cellular material from live influenza-exposed cells, subsequently mature and cross-present viral antigens very efficiently to specific CD8+ T cells. Therefore, during viral infection PDC not only secrete immunomodulatory cytokines, but also recognize infected cells and function as antigen cross-presenting cells to trigger the anti-viral immune response