20 research outputs found

    Correlations of Behavioral Deficits with Brain Pathology Assessed through Longitudinal MRI and Histopathology in the R6/2 Mouse Model of HD

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    Huntington's disease (HD) is caused by the expansion of a CAG repeat in the huntingtin (HTT) gene. The R6/2 mouse model of HD expresses a mutant version of exon 1 HTT and develops motor and cognitive impairments, a widespread huntingtin (HTT) aggregate pathology and brain atrophy. Despite the vast number of studies that have been performed on this model, the association between the molecular and cellular neuropathology with brain atrophy, and with the development of behavioral phenotypes remains poorly understood. In an attempt to link these factors, we have performed longitudinal assessments of behavior (rotarod, open field, passive avoidance) and of regional brain abnormalities determined through magnetic resonance imaging (MRI) (whole brain, striatum, cortex, hippocampus, corpus callosum), as well as an end-stage histological assessment. Detailed correlative analyses of these three measures were then performed. We found a gender-dependent emergence of motor impairments that was associated with an age-related loss of regional brain volumes. MRI measurements further indicated that there was no striatal atrophy, but rather a lack of striatal growth beyond 8 weeks of age. T2 relaxivity further indicated tissue-level changes within brain regions. Despite these dramatic motor and neuroanatomical abnormalities, R6/2 mice did not exhibit neuronal loss in the striatum or motor cortex, although there was a significant increase in neuronal density due to tissue atrophy. The deposition of the mutant HTT (mHTT) protein, the hallmark of HD molecular pathology, was widely distributed throughout the brain. End-stage histopathological assessments were not found to be as robustly correlated with the longitudinal measures of brain atrophy or motor impairments. In conclusion, modeling pre-manifest and early progression of the disease in more slowly progressing animal models will be key to establishing which changes are causally related. © 2013 Rattray et al

    In Situ Imaging of Bacterial Outer Membrane Projections and Associated Protein Complexes Using Electron Cryo-Tomography

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    The ability to produce outer membrane projections in the form of tubular membrane extensions (MEs) and membrane vesicles (MVs) is a widespread phenomenon among diderm bacteria. Despite this, our knowledge of the ultrastructure of these extensions and their associated protein complexes remains limited. Here, we surveyed the ultrastructure and formation of MEs and MVs, and their associated protein complexes, in tens of thousands of electron cryo-tomograms of ~90 bacterial species that we have collected for various projects over the past 15 years (Jensen lab database), in addition to data generated in the Briegel lab. We identified outer MEs and MVs in 13 diderm bacterial species and classified several major ultrastructures: (1) tubes with a uniform diameter (with or without an internal scaffold), (2) tubes with irregular diameter, (3) tubes with a vesicular dilation at their tip, (4) pearling tubes, (5) connected chains of vesicles (with or without neck-like connectors), (6) budding vesicles and nanopods. We also identified several protein complexes associated with these MEs and MVs which were distributed either randomly or exclusively at the tip. These complexes include a secretin-like structure and a novel crown-shaped structure observed primarily in vesicles from lysed cells. In total, this work helps to characterize the diversity of bacterial membrane projections and lays the groundwork for future research in this field

    Roadmap on emerging concepts in the physical biology of bacterial biofilms: from surface sensing to community formation

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    Bacterial biofilms are communities of bacteria that exist as aggregates that can adhere to surfaces or be free-standing. This complex, social mode of cellular organization is fundamental to the physiology of microbes and often exhibits surprising behavior. Bacterial biofilms are more than the sum of their parts: single-cell behavior has a complex relation to collective community behavior, in a manner perhaps cognate to the complex relation between atomic physics and condensed matter physics. Biofilm microbiology is a relatively young field by biology standards, but it has already attracted intense attention from physicists. Sometimes, this attention takes the form of seeing biofilms as inspiration for new physics. In this roadmap, we highlight the work of those who have taken the opposite strategy: we highlight the work of physicists and physical scientists who use physics to engage fundamental concepts in bacterial biofilm microbiology, including adhesion, sensing, motility, signaling, memory, energy flow, community formation and cooperativity. These contributions are juxtaposed with microbiologists who have made recent important discoveries on bacterial biofilms using state-of-the-art physical methods. The contributions to this roadmap exemplify how well physics and biology can be combined to achieve a new synthesis, rather than just a division of labor

    Brain size regulations by cbp haploinsufficiency evaluated by in-vivo MRI based volumetry

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    The Rubinstein-Taybi Syndrome (RSTS) is a congenital disease that affects brain development causing severe cognitive deficits. In most cases the disease is associated with dominant mutations in the gene encoding the CREB binding protein (CBP). In this work, we present the first quantitative analysis of brain abnormalities in a mouse model of RSTS using magnetic resonance imaging (MRI) and two novel self-developed automated algorithms for image volumetric analysis. Our results quantitatively confirm key syndromic features observed in RSTS patients, such as reductions in brain size (-16.31%, p < 0.05), white matter volume (-16.00%, p < 0.05), and corpus callosum (-12.40%, p < 0.05). Furthermore, they provide new insight into the developmental origin of the disease. By comparing brain tissues in a region by region basis between cbp(+/-) and cbp(+/+) littermates, we found that cbp haploinsufficiency is specifically associated with significant reductions in prosencephalic tissue, such us in the olfactory bulb and neocortex, whereas regions evolved from the embryonic rhombencephalon were spared. Despite the large volume reductions, the proportion between gray-, white-matter and cerebrospinal fluid were conserved, suggesting a role of CBP in brain size regulation. The commonalities with holoprosencephaly and arhinencephaly conditions suggest the inclusion of RSTS in the family of neuronal migration disorders.We are grateful to Begona Fernandez for her excellent technical assistance. We would like to thank S. Sawiak (Wolfson Imaging Centre, University of Cambridge, Cambridge, United Kingdom) for the mouse brain tissue probability maps and the SPMmouse plug-in, and to N. Kovacevic (Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada) for the atlas of the mouse brain. Supported by grants from the Spanish MINECO to S.C. (BFU 2012-39958) and MINECO and FEDER to D.M. (TEC 2012-33778) and from MINECO (SAF2011-22855) and Generalitat Valenciana (Prometeo/2012/005) to A.B. The Instituto de Neurociencias is "Centre of Excellence Severo Ochoa".Ateca Cabarga, JC.; Cosa, A.; Pallares, V.; Lopez-Atalaya, JP.; Barco, A.; Canals, S.; Moratal Pérez, D. (2015). Brain size regulations by cbp haploinsufficiency evaluated by in-vivo MRI based volumetry. Scientific Reports. 5. https://doi.org/10.1038/srep16256S5Rubinstein, J. H. & Taybi, H. Broad thumbs and toes and facial abnormalities. A possible mental retardation syndrome. Am J Dis Child 105, 588–608 (1963).Van Belzen, M., Bartsch, O., Lacombe, D., Peters, D. J. & Hennekam, R. C. Rubinstein-Taybi syndrome (CREBBP, EP300). Eur J Hum Genet. 19, preceeding 118–120 (2011).Hennekam, R. C. 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    Impact of an Electronic Pain andOpioid Risk Assessment Program: Are There Improvements in PatientEncounters and Clinic Notes?

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    A comprehensive electronic self-report assessment, called PainCAS® (Clinical Assessment System), was developed and implemented in three clinics. PainCAS captures demographic information, pain assessment, quality-of-life variables, and contains validated, electronic versions of screeners for risk of aberrant opioid-related behaviors (the SOAPP and COMM). This investigation sought to determine the impact of PainCAS on documentation of pain and opioid risk evaluations. Exploratory hypotheses examined changes in the content of the patient-provider interaction and any impact on outcome. METHODS: In study 1, chart reviews were conducted between pain patients who completed the electronic program (N = 89) and controls who represented standard of care (N = 120). In study 2, two groups of chronic pain patients (treatment-as-usual Control condition = 75, PainCAS Experimental condition = 72) were interviewed after completing their index clinic visit and completed mailed questionnaires 3 months later. RESULTS: Results revealed significantly more key, pain-relevant chart elements documented in charts of patients who completed the PainCAS than those using a traditional paper questionnaire (Study 1

    Roadmap on emerging concepts in the physical biology of bacterial biofilms: from surface sensing to community formation

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    Bacterial biofilms are communities of bacteria that exist as aggregates that can adhere to surfaces or be free-standing. This complex, social mode of cellular organization is fundamental to the physiology of microbes and often exhibits surprising behaviour. Bacterial biofilms are more than the sum of their parts: Single cell behaviour has a complex relation to collective community behaviour, in a manner perhaps cognate to the complex relation between atomic physics and condensed matter physics. Biofilm microbiology is a relatively young field by biology standards, but it has already attracted intense attention from physicists. Sometimes, this attention takes the form of seeing biofilms as inspiration for new physics. In this roadmap, we highlight the work of those who have taken the opposite strategy: We highlight work of physicists and physical scientists who use physics to engage fundamental concepts in bacterial biofilm microbiology, including adhesion, sensing, motility, signalling, memory, energy flow, community formation and cooperativity. These contributions are juxtaposed with microbiologists who have made recent important discoveries on bacterial biofilms using state-of-the-art physical methods. The contributions to this roadmap exemplify how well physics and biology can be combined to achieve a new synthesis, rather than just a division of labour
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