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Search Results: 1 - 10 of 401592 matches for " Euan M. Wallace "
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Amnion Epithelial Cells as a Candidate Therapy for Acute and Chronic Lung Injury
Ryan J. Hodges,Rebecca Lim,Graham Jenkin,Euan M. Wallace
Stem Cells International , 2012, DOI: 10.1155/2012/709763
Abstract: Acute and chronic lung injury represents a major and growing global burden of disease. For many of these lung diseases, the damage is irreparable, exhausting the host’s ability to regenerate new lung, and current therapies are simply supportive rather than restorative. Cell-based therapies offer the promise of tissue regeneration for many organs. In this paper, we examine the potential application of amnion epithelial cells, derived from the term placenta, to lung regeneration. We discuss their unique properties of plasticity and immunomodulation, reviewing the experimental evidence that amnion epithelial cells can prevent and repair lung injury, offering the potential to be applied to both neonatal, childhood, and adult lung disease. It is amazing to suggest that the placenta may offer renewed life after birth as well as securing new life before. 1. Introduction Chronic lung diseases, in both children and adults, are leading causes of morbidity and mortality worldwide, estimated to account for about 10% of global mortality [1]. It has been estimated by the World Health Organization that, by 2030, chronic lung disease, mainly caused by tobacco smoking, occupational irritant exposure and pollution, will become the third most common cause of death worldwide [1]. However, mortality is just the tip of the iceberg. A recent economic analysis of the burden of chronic lung disease in Australia revealed that almost 1 in 5 adults aged 40 or older have chronic obstructive pulmonary disease (COPD) to some degree, with half of these individuals having advanced disease [2]. The estimated financial cost of COPD in Australia in 2008 was nearly $9 billion. Further, chronic lung disease does not only affect adults. About 1 in 80 children aged under 10 suffer morbidity from COPD. In particular, over recent decades advances in perinatal care have greatly improved the survival chances of very preterm babies, principally through the reduction of acute respiratory distress syndrome (RDS) by antenatal corticosteroids and postnatal surfactant therapies [3, 4]. However, almost a third of these survivors develop chronic neonatal lung disease, so called bronchopulmonary dysplasia (BPD), a disease with the consequent long-term burdens of childhood respiratory dysfunction and neurodevelopmental delay [5]. Unfortunately, both neonatal BPD and adult COPD have an important feature in common. Neither have an effective treatment. Accordingly, together, these childhood and adult chronic lung conditions represent a significant and growing burden of disease for which there is no targeted
Rasch scaling procedures for informing development of a valid Fetal Surveillance Education Program multiple-choice assessment
Nathan Zoanetti, Patrick Griffin, Mark Beaves, Euan M Wallace
BMC Medical Education , 2009, DOI: 10.1186/1472-6920-9-20
Abstract: The Rasch item response model was employed for item and test analysis and to empirically derive the substantive interpretation of the assessment variable. This interpretation was then compared to the hierarchy of competencies specified a priori by a team of eight subject-matter experts. Classical Test Theory analyses were also conducted.A high level of agreement between the hypothesised and derived variable provided evidence of construct validity. Item and test indices from Rasch analysis and Classical Test Theory analysis suggested that the current test form was of moderate quality. However, the analyses made clear the required steps for establishing a valid assessment of sufficient psychometric quality. These steps included: increasing the number of items from 40 to 50 in the first instance, reviewing ineffective items, targeting new items to specific content and difficulty gaps, and formalising the assessment blueprint in light of empirical information relating item structure to item difficulty.The application of the Rasch model for criterion-referenced assessment validation with an expert stakeholder group is herein described. Recommendations for subsequent item and test construction are also outlined in this article.It is widely recognised that a significant number of adverse obstetric outcomes continue to arise from inappropriate use or interpretation of intrapartum fetal surveillance [1-4]. In both the United Kingdom and Australia, national reports on perinatal morbidity and mortality have highlighted that deficiencies in fetal surveillance practice continue to contribute significantly to the burden of adverse outcomes [2,4]. This has led to a call for regular training in fetal surveillance for all staff involved in the care of women in labour [1].In light of these national reports and the UK recommendations, it is perhaps surprising that options for formal education and credentialing in fetal surveillance remain limited. A recent survey of education and cred
Ventilation before Umbilical Cord Clamping Improves the Physiological Transition at Birth
Sasmira Bhatt,Graeme R. Polglase,Euan M. Wallace,Arjan B. te Pas,Stuart B. Hooper
Frontiers in Pediatrics , 2014, DOI: 10.3389/fped.2014.00113
Abstract: The transition from a fetus to a neonate at birth represents a critical phase in our life. Most infants make this transition without complications, but preterm infants usually require some form of assistance due to immature cardiopulmonary systems that predispose them to lifelong sequelae. As the incidence of preterm birth is increasing, there is now an urgent need for the development of management strategies that facilitate this transition, which will likely include improved strategies for the management of the maternal third stage of labor. For instance, recent studies on the physiological transition at birth have led to the discovery that establishing ventilation in the infant before the umbilical cord is clamped greatly stabilizes the cardiovascular transition at birth. While most benefits of delayed clamping previously have been attributed to an increase in placenta to infant blood transfusion, clearly there are other significant benefits for the infant, which are not well understood. Nevertheless, if ventilation can be established before cord clamping in a preterm infant, the large adverse changes in cardiac function that normally accompanies umbilical cord clamping can be avoided. As preterm infants have an immature cerebral vascular bed, large swings in cardiovascular function places them at high risk of cerebral vascular rupture and the associated increased risk of mortality and morbidity. In view of the impact that cord clamping has on the cardiovascular transition at birth, it is also time to re-examine some of the strategies used in the management of the third stage of labor. These include the appropriate timing of uterotonic administration in relation to delivery of the infant and placenta. As there is a lack of evidence on the effects these individual practices have on the infant, there is a necessity to improve our understanding of their impact in order to develop strategies that facilitate the transition to newborn life.
The role of the avian hippocampus in spatial memory
Euan M. Macphail
Psicológica , 2002,
Abstract: Avian hippocampal function is surveyed, using data drawn from three areas: conventional laboratory paradigms, pigeon navigation, and food-storing. Damage to the avian hippocampus disrupts performance in laboratory tasks that tap spatial learning and memory, and also disrupts both pigeon homing and cache recovery by food-storing birds. Further evidence of hippocampal involvement in food-storing is provided by the fact that the hippocampus of food-storing birds is selectively enlarged. These findings lend support to the notion that the hippocampus plays a critical role in spatial learning and memory. However, avian hippocampal lesions (like mammalian hippocampal lesions) also disrupt certain laboratory tasks that do not have an overt spatial component. Moreover, analysis of the effects of hippocampal lesions on navigation find, first, that basic navigational processes are left intact, and second, that at least some of the disruption of homing may be caused by disruption of the associability of information derived from the sun compass - a non-spatial deficit. Finally, attempts to demonstrate that the enlarged hippocampus of food-storing birds is associated with enhanced spatial memory have failed to deliver conclusive support. The extensive parallels between effects of hippocampal lesions in birds and mammals suggest that both the spatial and the non-spatial deficits form part of a single syndrome, one that cannot readily be explained in terms of disruption of specifically spatial processes.
Human Amnion Epithelial Cells Induced to Express Functional Cystic Fibrosis Transmembrane Conductance Regulator
Sean V. Murphy, Rebecca Lim, Philip Heraud, Marian Cholewa, Mark Le Gros, Martin D. de Jonge, Daryl L. Howard, David Paterson, Courtney McDonald, Anthony Atala, Graham Jenkin, Euan M. Wallace
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046533
Abstract: Cystic fibrosis, an autosomal recessive disorder caused by a mutation in a gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), remains a leading cause of childhood respiratory morbidity and mortality. The respiratory consequences of cystic fibrosis include the generation of thick, tenacious mucus that impairs lung clearance, predisposing the individual to repeated and persistent infections, progressive lung damage and shortened lifespan. Currently there is no cure for cystic fibrosis. With this in mind, we investigated the ability of human amnion epithelial cells (hAECs) to express functional CFTR. We found that hAECs formed 3-dimensional structures and expressed the CFTR gene and protein after culture in Small Airway Growth Medium (SAGM). We also observed a polarized CFTR distribution on the membrane of hAECs cultured in SAGM, similar to that observed in polarized airway cells in vivo. Further, hAECs induced to express CFTR possessed functional iodide/chloride (I?/Cl?) ion channels that were inhibited by the CFTR-inhibitor CFTR-172, indicating the presence of functional CFTR ion channels. These data suggest that hAECs may be a promising source for the development of a cellular therapy for cystic fibrosis.
A model of gene-gene and gene-environment interactions and its implications for targeting environmental interventions by genotype
Helen M Wallace
Theoretical Biology and Medical Modelling , 2006, DOI: 10.1186/1742-4682-3-35
Abstract: A new model for gene-gene and gene-environment interactions is developed that abandons the assumptions of the classical twin study, including Fisher's (1918) assumption that genes act as risk factors for common traits in a manner necessarily dominated by an additive polygenic term. Provided there are no confounders, the model can be used to implement a top-down approach to quantifying the potential utility of genetic prediction and prevention, using twin, family and environmental data. The results describe a solution space for each disease or trait, which may or may not include the classical twin study result. Each point in the solution space corresponds to a different model of genotypic risk and gene-environment interaction.The results show that the potential for reducing the incidence of common diseases using environmental interventions targeted by genotype may be limited, except in special cases. The model also confirms that the importance of an individual's genotype in determining their risk of complex diseases tends to be exaggerated by the classical twin studies method, owing to the 'equal environments' assumption and the assumption of no gene-environment interaction. In addition, if phenotypes are genetically robust, because of epistasis, a largely environmental explanation for shared sibling risk is plausible, even if the classical heritability is high. The results therefore highlight the possibility – previously rejected on the basis of twin study results – that inherited genetic variants are important in determining risk only for the relatively rare familial forms of diseases such as breast cancer. If so, genetic models of familial aggregation may be incorrect and the hunt for additional susceptibility genes could be largely fruitless.Some geneticists have predicted a genetic revolution in healthcare: involving a future in which individuals take a battery of genetic tests, at birth or later in life, to determine their individual 'genetic susceptibility' to
Diagnosis of Early Chronic Pancreatitis by Endoscopic Ultrasound. Are We There Yet?
Raimondo M,Wallace MB
JOP Journal of the Pancreas , 2004,
Abstract: The diagnosis of chronic pancreatitis at an early stage is a clinical challenge. A major limitation is the inability of clinicians to obtain a tissue or histological sample to confirm the clinical diagnosis. Currently available imaging modalities have limited sensitivity or specificity for diagnosing early chronic pancreatitis. Endoscopic ultrasonography (EUS), introduced in the early 1980's, was first developed to image the pancreas. It overcame many of the limitations (abdominal gas and fat) of transabdominal ultrasonography when evaluating patients for possible pancreatic diseases. To date, EUS represents the most promising imaging modality for diagnosing chronic pancreatitis. Contrary to endoscopic retrograde pancreatography (ERCP), EUS has a very low risk of complications and can detect abnormalities suggestive of chronic pancreatitis in the pancreatic parenchyma and ductal system which are not visible on any other imaging modality. The minimal changes in echotexture are difficult to interpret because there is no reliable gold standard confirmatory test. There is now some evidence in the literature suggesting that these early changes detected by EUS correlate with the histological changes of chronic pancreatitis and may predict progression to more advanced disease. The EUS diagnosis of chronic pancreatitis relies on quantitative (more than qualitative) parenchymal and ductal criteria found during evaluation of the pancreas. It is generally accepted that, in the absence of any criteria, chronic pancreatitis is unlikely, whereas in the presence of 5 or more criteria (out of 9-11) chronic pancreatitis is likely although ERCP and pancreatic function tests may still be normal. The diagnostic significance of patients with fewer (1-4) criteria found on EUS is currently unclear, particularly when other diagnostic tests such as ERCP and function testing are normal. In these cases, there is a potential for "over-diagnosis" of chronic pancreatitis, since the EUS changes cannot be confirmed by other modalities. How can we better understand the implications of EUS detected changes when other tests are normal?
Space-time correlations in turbulent flow: A review
James M. Wallace
Physics , 2015, DOI: 10.1063/2.1402203
Abstract: This paper reviews some of the principal uses, over almost seven decades, of correlations, in both Eulerian and Lagrangian frames of reference, of properties of turbulent flows at variable spatial locations and variable time instants. Commonly called space--time correlations, they have been fundamental to theories and models of turbulence as well as for the analyses of experimental and direct numerical simulation turbulence data.
Ontogeny, structure and moulting of Parabolina frequens argentina (Kayser) (Trilobita, Olenidae) from the Furongian of northwestern Argentina
Tortello,M. Franco; Clarkson,Euan N.K.;
Ameghiniana , 2008,
Abstract: parabolina frequens argentina (kayser) (trilobita, olenidae) is a guide fossil occurring in different assemblages and lithologies of the upper cambrian (furongian) of northwestern argentina. the black and dark grey shales of the lampazar formation at sierra de cajas and the santa rosita formation (lower part) at iruya and alfarcito (jujuy and salta provinces) contain numerous well-preserved specimens at different stages of development. the juveniles represent anaprotaspis, metaprotaspis and degrees 0-11 meraspis. the latter exhibit a high variability related with the pattern of glabellar furrows and lobes, the sagittal length of the thoracic segments, the splay and length of the genal and thoracic spines, the relative width of the axis, and the relative development of the axial tubercles. as in other species of parabolina, the meraspid stages of p. frequens argentina do not form well-defined instar groupings. besides, in the adult specimens the length of the anterior cephalic border and the preglabellar field are also variable characters. the hypostome is characterized by having almost completely reduced anterior wings; it lies in close association with the ventral doublure (conterminant condition). although some authors suggested that p. frequens argentina and p. frequens frequens (barrande) could be synonyms, these taxa differ in having distinctive pygidia and hypostomes. many exoskeletal configurations can be interpreted as exuviae. from a functional point of view, it is likely that the genal and macropleural spines on the 8th thoracic segment supported the body of the trilobite when resting on the sea floor. the exoskeleton can be reconstructed in two alternative postures, the "alert" and "relaxed" attitudes.
Effect of Nutrient Restriction on Social Transmission of Food Preferences Depends on Nutrient and Species  [PDF]
Darryl J. Mayeaux, Maxwell B. Wallace, Anne M. Young
Journal of Behavioral and Brain Science (JBBS) , 2014, DOI: 10.4236/jbbs.2014.412056
Abstract: For omnivores to determine whether an unfamiliar item is an appropriate food, they could rely on personal information from sampling it themselves or rely on less risky observation of whether other individuals eat the item. Availability of information about food from social companions in group-living species is one of the benefits of group life. Adults of solitary-living species, however, seem typically less likely to rely on social information about food choice. If an individual faced a nutritional deficit, it would seem to increase the value of public information. This study addresses whether dietary restriction from certain nutrients (sodium, potassium, protein, carbohydrates) affects reliance on information about food from conspecifics. Without nutrient restriction, group-living Norway rats (Rattus norvegicus) preferred the diet that they smelled on the breath of a conspecific demonstrator, but solitary-living Syrian hamsters (Mesocricetus auratus) avoided it. Protein restriction yielded similar results as measured one hour into a diet choice test. Potassium restriction, however, reversed the pattern: rats avoided the demonstrator’s diet but hamsters preferred it. Clearly, the valence of social information depended on the nutrient from which individuals were restricted and the species under study. This could be related to the contrasting social organization that members of each species generate. Neither species relied on social information about the availability of a nutrient from which they were restricted if they could taste that nutrient for themselves (sodium, carbohydrates).
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