222 research outputs found

    Cerebral blood flow predicts differential neurotransmitter activity

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    Application of metabolic magnetic resonance imaging measures such as cerebral blood flow in translational medicine is limited by the unknown link of observed alterations to specific neurophysiological processes. In particular, the sensitivity of cerebral blood flow to activity changes in specific neurotransmitter systems remains unclear. We address this question by probing cerebral blood flow in healthy volunteers using seven established drugs with known dopaminergic, serotonergic, glutamatergic and GABAergic mechanisms of action. We use a novel framework aimed at disentangling the observed effects to contribution from underlying neurotransmitter systems. We find for all evaluated compounds a reliable spatial link of respective cerebral blood flow changes with underlying neurotransmitter receptor densities corresponding to their primary mechanisms of action. The strength of these associations with receptor density is mediated by respective drug affinities. These findings suggest that cerebral blood flow is a sensitive brain-wide in-vivo assay of metabolic demands across a variety of neurotransmitter systems in humans

    Soft elasticity optimises dissipation in 3D-printed liquid crystal elastomers

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    Soft-elasticity in monodomain liquid crystal elastomers (LCEs) is promising for impact-absorbing applications where strain energy is ideally absorbed at constant stress. Conventionally, compressive and impact studies on LCEs have not been performed given the notorious difficulty synthesizing sufficiently large monodomain devices. Here, we use direct-ink writing 3D printing to fabricate bulk (>cm3) monodomain LCE devices and study their compressive soft-elasticity over 8 decades of strain rate. At quasi-static rates, the monodomain soft-elastic LCE dissipated 45% of strain energy while comparator materials dissipated less than 20%. At strain rates up to 3000 s−1, our soft-elastic monodomain LCE consistently performed closest to an ideal-impact absorber. Drop testing reveals soft-elasticity as a likely mechanism for effectively reducing the severity of impacts – with soft elastic LCEs offering a Gadd Severity Index 40% lower than a comparable isotropic elastomer. Lastly, we demonstrate tailoring deformation and buckling behavior in monodomain LCEs via the printed director orientation

    Capturing the personal through the lens of the professional: The use of external data sources in autoethnography

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    This article shows how external data sources can be utilised in autoethnographic research. Beginning with an account of a critical incident that examines the incompatibility of private and professional identities, I show how, through the collection of data sources, I capture the impact of homophobic and heteronormative discursive practices on health, wellbeing and identity. In the critical incident, I explore how I prospered as a teacher at a British village school for almost 10 years by censoring my sexuality and carefully managing the intersection between my private and professional identities. However, when a malicious and homophobic neighbour and parent of children at the school exposed my sexuality to the Headteacher, I learned the extent to which the rural school community privileged and protected the heteronormative discourse. A poststructuralist theoretical framework underpins this article. My experience of being a subject is understood as the outcome of discursive practices. Sexual identity, teacher identity and autoethnographer identity are understood to be fluid, and constantly produced and reproduced in response to social, cultural and political influences. The article describes how email correspondence, medical records and notes from a course of cognitive behaviour therapy were deployed to augment my personal recollection and give a depth and richness to the narrative. As the critical incident became a police matter, examination takes place of how I sought to obtain and utilise data from the police national computer in the research. Attempts to collect data from the police and Crown Prosecution Service were problematic and provided an unexpected development in the research and offered additional insight into the nature of the British rural community and its police force

    Organizational theory for dissemination and implementation research

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    Abstract Background Even under optimal internal organizational conditions, implementation can be undermined by changes in organizations’ external environments, such as fluctuations in funding, adjustments in contracting practices, new technology, new legislation, changes in clinical practice guidelines and recommendations, or other environmental shifts. Internal organizational conditions are increasingly reflected in implementation frameworks, but nuanced explanations of how organizations’ external environments influence implementation success are lacking in implementation research. Organizational theories offer implementation researchers a host of existing, highly relevant, and heretofore largely untapped explanations of the complex interaction between organizations and their environment. In this paper, we demonstrate the utility of organizational theories for implementation research. Discussion We applied four well-known organizational theories (institutional theory, transaction cost economics, contingency theories, and resource dependency theory) to published descriptions of efforts to implement SafeCare, an evidence-based practice for preventing child abuse and neglect. Transaction cost economics theory explained how frequent, uncertain processes for contracting for SafeCare may have generated inefficiencies and thus compromised implementation among private child welfare organizations. Institutional theory explained how child welfare systems may have been motivated to implement SafeCare because doing so aligned with expectations of key stakeholders within child welfare systems’ professional communities. Contingency theories explained how efforts such as interagency collaborative teams promoted SafeCare implementation by facilitating adaptation to child welfare agencies’ internal and external contexts. Resource dependency theory (RDT) explained how interagency relationships, supported by contracts, memoranda of understanding, and negotiations, facilitated SafeCare implementation by balancing autonomy and dependence on funding agencies and SafeCare developers. Summary In addition to the retrospective application of organizational theories demonstrated above, we advocate for the proactive use of organizational theories to design implementation research. For example, implementation strategies should be selected to minimize transaction costs, promote and maintain congruence between organizations’ dynamic internal and external contexts over time, and simultaneously attend to organizations’ financial needs while preserving their autonomy. We describe implications of applying organizational theory in implementation research for implementation strategies, the evaluation of implementation efforts, measurement, research design, theory, and practice. We also offer guidance to implementation researchers for applying organizational theory

    Acute Regulation of Cardiac Metabolism by the Hexosamine Biosynthesis Pathway and Protein O-GlcNAcylation

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    OBJECTIVE: The hexosamine biosynthesis pathway (HBP) flux and protein O-linked N-acetyl-glucosamine (O-GlcNAc) levels have been implicated in mediating the adverse effects of diabetes in the cardiovascular system. Activation of these pathways with glucosamine has been shown to mimic some of the diabetes-induced functional and structural changes in the heart; however, the effect on cardiac metabolism is not known. Therefore, the primary goal of this study was to determine the effects of glucosamine on cardiac substrate utilization. METHODS: Isolated rat hearts were perfused with glucosamine (0-10 mM) to increase HBP flux under normoxic conditions. Metabolic fluxes were determined by (13)C-NMR isotopomer analysis; UDP-GlcNAc a precursor of O-GlcNAc synthesis was assessed by HPLC and immunoblot analysis was used to determine O-GlcNAc levels, phospho- and total levels of AMPK and ACC, and membrane levels of FAT/CD36. RESULTS: Glucosamine caused a dose dependent increase in both UDP-GlcNAc and O-GlcNAc levels, which was associated with a significant increase in palmitate oxidation with a concomitant decrease in lactate and pyruvate oxidation. There was no effect of glucosamine on AMPK or ACC phosphorylation; however, membrane levels of the fatty acid transport protein FAT/CD36 were increased and preliminary studies suggest that FAT/CD36 is a potential target for O-GlcNAcylation. CONCLUSION/INTERPRETATION: These data demonstrate that acute modulation of HBP and protein O-GlcNAcylation in the heart stimulates fatty acid oxidation, possibly by increasing plasma membrane levels of FAT/CD36, raising the intriguing possibility that the HBP and O-GlcNAc turnover represent a novel, glucose dependent mechanism for regulating cardiac metabolism

    Preference for biological motion is reduced in ASD: implications for clinical trials and the search for biomarkers

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    Background: The neurocognitive mechanisms underlying autism spectrum disorder (ASD) remain unclear. Progress has been largely hampered by small sample sizes, variable age ranges and resulting inconsistent findings. There is a pressing need for large definitive studies to delineate the nature and extent of key case/control differences to direct research towards fruitful areas for future investigation. Here we focus on perception of biological motion, a promising index of social brain function which may be altered in ASD. In a large sample ranging from childhood to adulthood, we assess whether biological motion preference differs in ASD compared to neurotypical participants (NT), how differences are modulated by age and sex and whether they are associated with dimensional variation in concurrent or later symptomatology. Methods: Eye-tracking data were collected from 486 6-to-30-year-old autistic (N = 282) and non-autistic control (N = 204) participants whilst they viewed 28 trials pairing biological (BM) and control (non-biological, CTRL) motion. Preference for the biological motion stimulus was calculated as (1) proportion looking time difference (BM-CTRL) and (2) peak look duration difference (BM-CTRL). Results: The ASD group showed a present but weaker preference for biological motion than the NT group. The nature of the control stimulus modulated preference for biological motion in both groups. Biological motion preference did not vary with age, gender, or concurrent or prospective social communicative skill within the ASD group, although a lack of clear preference for either stimulus was associated with higher social-communicative symptoms at baseline. Limitations: The paired visual preference we used may underestimate preference for a stimulus in younger and lower IQ individuals. Our ASD group had a lower average IQ by approximately seven points. 18% of our sample was not analysed for various technical and behavioural reasons. Conclusions: Biological motion preference elicits small-to-medium-sized case–control effects, but individual differences do not strongly relate to core social autism associated symptomatology. We interpret this as an autistic difference (as opposed to a deficit) likely manifest in social brain regions. The extent to which this is an innate difference present from birth and central to the autistic phenotype, or the consequence of a life lived with ASD, is unclear

    Does physiotherapy reduce the incidence of postoperative complications in patients following pulmonary resection via thoracotomy? a protocol for a randomised controlled trial

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    Background: Postoperative pulmonary and shoulder complications are important causes of postoperative morbidity following thoracotomy. While physiotherapy aims to prevent or minimise these complications, currently there are no randomised controlled trials to support or refute effectiveness of physiotherapy in this setting. Methods/Design: This single blind randomised controlled trial aims to recruit 184 patients following lung resection via open thoracotomy. All subjects will receive a preoperative physiotherapy information booklet and following surgery will be randomly allocated to a Treatment Group receiving postoperative physiotherapy or a Control Group receiving standard care nursing and medical interventions but no physiotherapy. The Treatment Group will receive a standardised daily physiotherapy programme to prevent respiratory and musculoskeletal complications. On discharge Treatment Group subjects will receive an exercise programme and exercise diary to complete. The primary outcome measure is the incidence of postoperative pulmonary complications, which will be determined on a daily basis whilst the patient is in hospital by a blinded assessor. Secondary outcome measures are the length of postoperative hospital stay, severity of pain, shoulder function as measured by the self-reported shoulder pain and disability index, and quality of life measured by the Medical Outcomes Study Short Form 36 v2 New Zealand standard version. Pain, shoulder function and quality of life will be measured at baseline, on discharge from hospital, one month and three months postoperatively. Additionally a subgroup of subjects will have measurement of shoulder range of movement and muscle strength by a blinded assessor. Discussion: Results from this study will contribute to the increasing volume of evidence regarding the effectiveness of physiotherapy following major surgery and will guide physiotherapists in their interventions for patients following thoracotomy. Trial registration: The study protocol is registered with the Australian and New Zealand Clinical Trials registry (ANZCTRN12605000201673)

    Mitochondrial Lactate Dehydrogenase Is Involved in Oxidative-Energy Metabolism in Human Astrocytoma Cells (CCF-STTG1)

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    Lactate has long been regarded as an end product of anaerobic energy production and its fate in cerebral metabolism has not been precisely delineated. In this report, we demonstrate, for the first time, the ability of a human astrocytic cell line (CCF-STTG1) to consume lactate and to generate ATP via oxidative phosphorylation. 13C-NMR and HPLC analyses aided in the identification of tricarboxylic acid (TCA) cyle metabolites and ATP in the astrocytic mitochondria incubated with lactate. Oxamate, an inhibitor of lactate dehydrogenase (LDH), abolished mitochondrial lactate consumption. Electrophoretic and fluorescence microscopic analyses helped localize LDH in the mitochondria. Taken together, this study implicates lactate as an important contributor to ATP metabolism in the brain, a finding that may significantly change our notion of how this important organ manipulates its energy budget
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