33 research outputs found

    Variable Fitness Impact of HIV-1 Escape Mutations to Cytotoxic T Lymphocyte (CTL) Response

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    Human lymphocyte antigen (HLA)-restricted CD8+ cytotoxic T lymphocytes (CTL) target and kill HIV-infected cells expressing cognate viral epitopes. This response selects for escape mutations within CTL epitopes that can diminish viral replication fitness. Here, we assess the fitness impact of escape mutations emerging in seven CTL epitopes in the gp120 Env and p24 Gag coding regions of an individual followed longitudinally from the time of acute HIV-1 infection, as well as some of these same epitopes recognized in other HIV-1-infected individuals. Nine dominant mutations appeared in five gp120 epitopes within the first year of infection, whereas all four mutations found in two p24 epitopes emerged after nearly two years of infection. These mutations were introduced individually into the autologous gene found in acute infection and then placed into a full-length, infectious viral genome. When competed against virus expressing the parental protein, fitness loss was observed with only one of the nine gp120 mutations, whereas four had no effect and three conferred a slight increase in fitness. In contrast, mutations conferring CTL escape in the p24 epitopes significantly decreased viral fitness. One particular escape mutation within a p24 epitope was associated with reduced peptide recognition and high viral fitness costs but was replaced by a fitness-neutral mutation. This mutation appeared to alter epitope processing concomitant with a reduced CTL response. In conclusion, CTL escape mutations in HIV-1 Gag p24 were associated with significant fitness costs, whereas most escape mutations in the Env gene were fitness neutral, suggesting a balance between immunologic escape and replicative fitness costs

    Role of antioxidant enzymes and small molecular weight antioxidants in the pathogenesis of age-related macular degeneration (AMD)

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    It Looks Good, but What is it Like to Live There? Exploring the Impact of Innovative Housing Design on Crime

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    This paper reports on the findings of a collaborative project (funded by the Home Office and managed by the Commission for Architecture and the Built Environment - CABE) which was conducted in late 2009 and early 2010. The project set out to strengthen and update the evidence base on the impact of design on a range of crime types – with a specific focus upon housing developments acclaimed for their innovative design and award winning architecture. This paper presents the findings of an in-depth assessment of the impact of housing design features on crime. Utilising a comprehensive data collection exercise, the specific design features of thousands of homes were collated and assessed against police recorded crime data. The design features were based upon the key elements of Crime Prevention Through Environmental Design (CPTED) including road layout, house design, surveillance, territoriality, car parking, communal space, management and maintenance and physical security. The unique and painstaking methodology not only provided an excellent dataset for analysis, but also highlighted the need both for greater conceptual clarity within CPTED and for crime-risk assessments to be based on the careful operationalisation and measurement of CPTED factors. As well as assessing the impact of specific (and combined) design features upon crime, the research also resulted in the production of a new data collection tool designed to address the weaknesses of existing checklists in assessing innovative contemporary developments, which are often unconventional in nature. The paper explores the degree of conflict and/or synergy between the traditional principles of CPTED and contemporary directions in architecture and design. Finally the paper considers the extent to which traditional CPTED principles remain relevant within contemporary residential developments and explores whether areas of revision are required

    Nest and maternal origin can influence morphology and locomotor performance of hatchling green turtles (Chelonia mydas)incubated in field nests

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    In numerous laboratory experiments involving the incubation of reptile eggs, both the maternal origin of eggs and the incubating environment (nest effect) have been demonstrated to influence hatchling phenotype. Although different hatchling phenotypes have been reported from natural nests, the separate effects of maternal origin and nest on hatchling phenotype in natural nests have not been demonstrated because in natural nests the two effects are confounded with each other. Here, we use a split clutch design to experimentally separate nest effects from maternal origin effects in field nests of green turtles (Chelonia mydas). We found both maternal origin and nest to influence hatchling morphology and locomotor performance in some but not all field nests. By using egg mass (maternal origin effect) and nest temperature (nest effect) in multiple regression analysis, we found maternal origin had a greater influence than nest temperature on the morphological attributes of hatchling mass and carapace size, but nest temperature had a greater influence than maternal origin on the performance attributes of self-righting time, self-righting propensity, swim thrust during the first 30 min of swimming, and power stroke rate during the first 30 min of swimming
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