453 research outputs found

    Perceptions and Determinants of Eating for Health and Performance in High-Level Male Adolescent Rugby Union Players

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    Sports nutrition recommendations provide guidance on dietary strategies to optimise sports performance. However, research indicates that young athletes often find it difficult to follow these guidelines in practice. Limited research exists on the determinants that influence adherence to sports nutrition guidelines. This study aimed to explore the perceptions and determinants of eating for health and performance in high-level male adolescent rugby union players. Determinants were explored using semi-structured individual interviews in New Zealand high-level male rugby union players (n = 20, 16⁝18 years). Interviews were recorded, transcribed, and then underwent thematic analysis. Perceptions of eating for health and performance included balance and variety, appropriate portions, and specific foods. Both adolescent- and sport-specific determinants influenced the food choices of participants. Determinants relevant to adolescent lifestyles included the influence of significant others such as peers and family but also included the taste, cost, convenience, and availability of food. Sports-specific determinants revolved around the desire to enhance sports performance, motivation to perform, and team culture. The media (mainstream and social media), physical appearance, and feeling good were identified as both adolescent- and sport-specific factors influencing food choice. These findings highlight the importance of having support and positive role modelling to help young athletes make optimal food choices for health and performance. Strategies to further enable healthy eating practices should aim to strengthen the support available to young athletes in the home, school, and sporting environments and should include education on appropriate social media use to inform eating for health and performance

    Inhibition of tyrosine kinase receptors by SU6668 promotes abnormal stromal development at the periphery of carcinomas

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    Dynamic contrast-enhanced (albumin-Gd-DTPA) magnetic resonance imaging, performed during 2 weeks of daily administration of an inhibitor of tyrosine kinase receptors (SU6668) in an HT-29 colon carcinoma model, revealed the onset of a hyper-enhancing rim, not observed in untreated tumours. To account for tissue heterogeneity in the quantitative analysis, we segmented tumours into three subunits automatically identified by cluster analysis of the enhancement curves using a k-means algorithm. Transendothelial permeability (Kps) and fractional plasma volume (fPV) were calculated in each subunit. An avascular and necrotic region, an intermediate zone and a well-vascularised periphery were reliably identified. During untreated tumour growth, the identified sub-regions did not substantially change their enhancement pattern. Treatment with SU6668 induced major changes at tumour periphery where a significant increase of Kps and fPV was observed with respect to control tumours. Histology revealed a sub-capsular layer composed of hyper-dense viable tumour cells in the periphery of untreated tumours. The rim of viable neoplastic cells was reduced in treated tumours, and replaced by loose connective tissue characterised by numerous vessels, which explains the observed hyper-enhancement. The present data show a peripheral abnormal development of cancer-associated stroma, indicative of an adaptive response to anti-angiogenic treatment

    Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes

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    Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable

    Dopamine Beta Hydroxylase Genotype Identifies Individuals Less Susceptible to Bias in Computer-Assisted Decision Making

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    Computerized aiding systems can assist human decision makers in complex tasks but can impair performance when they provide incorrect advice that humans erroneously follow, a phenomenon known as “automation bias.” The extent to which people exhibit automation bias varies significantly and may reflect inter-individual variation in the capacity of working memory and the efficiency of executive function, both of which are highly heritable and under dopaminergic and noradrenergic control in prefrontal cortex. The dopamine beta hydroxylase (DBH) gene is thought to regulate the differential availability of dopamine and norepinephrine in prefrontal cortex. We therefore examined decision-making performance under imperfect computer aiding in 100 participants performing a simulated command and control task. Based on two single nucleotide polymorphism (SNPs) of the DBH gene, −1041 C/T (rs1611115) and 444 G/A (rs1108580), participants were divided into groups of low and high DBH enzyme activity, where low enzyme activity is associated with greater dopamine relative to norepinephrine levels in cortex. Compared to those in the high DBH enzyme activity group, individuals in the low DBH enzyme activity group were more accurate and speedier in their decisions when incorrect advice was given and verified automation recommendations more frequently. These results indicate that a gene that regulates relative prefrontal cortex dopamine availability, DBH, can identify those individuals who are less susceptible to bias in using computerized decision-aiding systems

    Abiotrophia defectiva knee prosthesis infection: A case report

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    <p>Abstract</p> <p>Background</p> <p><it>Abiotrophia </it>species have rarely been implicated in osteoarticular infections. We report one case of an <it>A. defectiva </it>knee prosthesis infection.</p> <p>Case presentation</p> <p>A 71-year-old man of Italian origin presented with pain and swelling of the knee four years after the implantation of a total knee replacement prosthesis. While standard culturing of the synovial fluid resulted in no isolation of microorganisms, the direct inoculation of the synovial fluid into a rich culture medium resulted in the identification of <it>A. defectiva </it>by polymerase chain reaction sequencing. Repeated attempts of culturing microorganisms from blood were negative, and echocardiograms and colonoscopies were unremarkable. High-dose amoxicillin for nine months and a two-stage replacement of the knee prosthesis led to full patient recovery by the time of the 12-month follow-up examination.</p> <p>Conclusions</p> <p>Because <it>Abiotrophia </it>spp. are fastidious microorganisms, it is likely that cases of <it>Abiotrophia </it>orthopedic infection are misdiagnosed as culture-negative infections. Direct inoculation of synovial fluids into rich broth medium and further polymerase chain reaction-based detection of culture-negative synovial fluids are key tests for accurate documentation and detection of these infections.</p

    Does child weight influence how mothers report their feeding practices?

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    Objectives. The present study aimed to ascertain whether parental reports of their feeding practices are associated with independent observations of these behaviours, and whether the reliability of maternal report depends upon the child's weight. Methods. A total of 56 mothers and their children ate a lunch to satiety which was videotaped and coded for maternal use of control during feeding. Mothers also completed questionnaires about their feeding practices and children were weighed and measured. Results. Maternal reports of controlling feeding practices were poorly related to independent observations of these behaviours in the laboratory. However, there was a significant interaction between child BMI z score and observed pressure to eat in predicting maternally reported pressure to eat. There was also a significant interaction between child BMI z score and observed maternal restriction with food in predicting maternally reported restriction. When decomposed, these interactions suggested that only mothers of relatively underweight children were accurate at reporting their use of pressure to eat when compared to independent observations. For mothers of relatively overweight children there was a significant negative relationship between observed and reported restriction over food. Conclusions. Overall there was poor correspondence between maternal reports and independent observations of the use of controlling feeding practices. Further research is needed to replicate these findings and to ascertain whether parents who are inaccurate at reporting their use of these feeding practices are unaware that they are using controlling feeding practices or whether they are responding in socially desirable ways to questionnaires assessing their feeding behaviour. Š 2011 Informa Healthcare

    Characterization of killer immunoglobulin-like receptor genetics and comprehensive genotyping by pyrosequencing in rhesus macaques

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    <p>Abstract</p> <p>Background</p> <p>Human killer immunoglobulin-like receptors (KIRs) play a critical role in governing the immune response to neoplastic and infectious disease. Rhesus macaques serve as important animal models for many human diseases in which KIRs are implicated; however, the study of KIR activity in this model is hindered by incomplete characterization of <it>KIR </it>genetics.</p> <p>Results</p> <p>Here we present a characterization of <it>KIR </it>genetics in rhesus macaques (<it>Macaca mulatta)</it>. We conducted a survey of <it>KIRs </it>in this species, identifying 47 novel full-length <it>KIR </it>sequences. Using this expanded sequence library to build upon previous work, we present evidence supporting the existence of 22 <it>Mamu-KIR </it>genes, providing a framework within which to describe macaque <it>KIRs</it>. We also developed a novel pyrosequencing-based technique for <it>KIR </it>genotyping. This method provides both comprehensive <it>KIR </it>genotype and frequency estimates of transcript level, with implications for the study of <it>KIRs </it>in all species.</p> <p>Conclusions</p> <p>The results of this study significantly improve our understanding of macaque <it>KIR </it>genetic organization and diversity, with implications for the study of many human diseases that use macaques as a model. The ability to obtain comprehensive KIR genotypes is of basic importance for the study of KIRs, and can easily be adapted to other species. Together these findings both advance the field of macaque KIRs and facilitate future research into the role of KIRs in human disease.</p

    Changes in joint coupling and variability during walking following tibialis posterior muscle fatigue

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    <p>Abstract</p> <p>Background</p> <p>The tibialis posterior muscle is believed to play a key role in controlling foot mechanics during the stance phase of gait. However, an experiment involving localised tibialis posterior muscle fatigue, and analysis of discrete rearfoot and forefoot kinematic variables, indicated that reduced force output of the tibialis posterior muscle did not alter rearfoot and forefoot motion during gait. Thus, to better understand how muscle fatigue affects foot kinematics and injury potential, the purpose of this study was to reanalyze the data and investigate shank, rearfoot and forefoot joint coupling and coupling variability during walking.</p> <p>Methods</p> <p>Twenty-nine participants underwent an exercise fatigue protocol aimed at reducing the force output of tibialis posterior. An eight camera motion analysis system was used to evaluate 3 D shank and foot joint coupling and coupling variability during treadmill walking both pre- and post-fatigue.</p> <p>Results</p> <p>The fatigue protocol was successful in reducing the maximal isometric force by over 30% and a concomitant increase in coupling motion of the shank in the transverse plane and forefoot in the sagittal and transverse planes relative to frontal plane motion of the rearfoot. In addition, an increase in joint coupling variability was measured between the shank and rearfoot and between the rearfoot and forefoot during the fatigue condition.</p> <p>Conclusions</p> <p>The reduced function of the tibialis posterior muscle following fatigue resulted in a disruption in typical shank and foot joint coupling patterns and an increased variability in joint coupling. These results could help explain tibialis posterior injury aetiology.</p
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