oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 470 )

2018 ( 837 )

2017 ( 779 )

2016 ( 1142 )

Custom range...

Search Results: 1 - 10 of 471286 matches for " Christopher A. Fowler "
All listed articles are free for downloading (OA Articles)
Page 1 /471286
Display every page Item
Model of Genetic Variation in Human Social Networks
James H. Fowler,Christopher T. Dawes,Nicholas A. Christakis
Quantitative Biology , 2008, DOI: 10.1073/pnas.0806746106
Abstract: Social networks exhibit strikingly systematic patterns across a wide range of human contexts. While genetic variation accounts for a significant portion of the variation in many complex social behaviors, the heritability of egocentric social network attributes is unknown. Here we show that three of these attributes (in-degree, transitivity, and centrality) are heritable. We then develop a "mirror network" method to test extant network models and show that none accounts for observed genetic variation in human social networks. We propose an alternative "Attract and Introduce" model with two simple forms of heterogeneity that generates significant heritability as well as other important network features. We show that the model is well suited to real social networks in humans. These results suggest that natural selection may have played a role in the evolution of social networks. They also suggest that modeling intrinsic variation in network attributes may be important for understanding the way genes affect human behaviors and the way these behaviors spread from person to person.
Health-Related Quality of Life and Overall Life Satisfaction in People with Serious Mental Illness
Amy L. Barnes,Meghan E. Murphy,Christopher A. Fowler,Melisa V. Rempfer
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/245103
Abstract: Quality of life (QoL) in people with schizophrenia and other serious mental illnesses (SMI) is an important outcome goal, yet there is no consistent definition of the construct. We examined three aspects of QoL in persons with SMI: overall life satisfaction, physical health-related QoL (HRQoL), and mental HRQoL. This study had two primary aims: first, to examine whether there are differences in physical and mental HRQoL in persons with SMI, and, second, to investigate the cognitive, clinical, and functional correlates of the three QoL indicators. Participants were 48 persons with SMI who completed assessments of QoL, cognition, functional capacity, psychiatric symptomatology, and medical comorbidity. Results indicate that participants experience similar levels of physical and mental HRQoL, and these two constructs are not related to one another. Physical HRQoL is associated with less medical comorbidity, while mental HRQoL is associated with negative and depressive symptoms. Overall life satisfaction was associated with fewer psychiatric symptoms and less medical comorbidity. This study adds to the important literature defining distinct domains of QoL and supports the necessity of addressing both physical and mental health factors as they relate to recovery and well-being among persons with SMI.
Corticolimbic Expression of TRPC4 and TRPC5 Channels in the Rodent Brain
Melissa A. Fowler, Kyriaki Sidiropoulou, Emin D. Ozkan, Christopher W. Phillips, Donald C. Cooper
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000573
Abstract: The canonical transient receptor potential (TRPC) channels are a family of non-selective cation channels that are activated by increases in intracellular Ca2+ and Gq/phospholipase C-coupled receptors. We used quantitative real-time PCR, in situ hybridization, immunoblots and patch-clamp recording from several brain regions to examine the expression of the predominant TRPC channels in the rodent brain. Quantitative real-time PCR of the seven TRPC channels in the rodent brain revealed that TRPC4 and TRPC5 channels were the predominant TRPC subtypes in the adult rat brain. In situ hybridization histochemistry and immunoblotting further resolved a dense corticolimbic expression of the TRPC4 and TRPC5 channels. Total protein expression of HIP TRPC4 and 5 proteins increased throughout development and peaked late in adulthood (6–9 weeks). In adults, TRPC4 expression was high throughout the frontal cortex, lateral septum (LS), pyramidal cell layer of the hippocampus (HIP), dentate gyrus (DG), and ventral subiculum (vSUB). TRPC5 was highly expressed in the frontal cortex, pyramidal cell layer of the HIP, DG, and hypothalamus. Detailed examination of frontal cortical layer mRNA expression indicated TRPC4 mRNA is distributed throughout layers 2–6 of the prefrontal cortex (PFC), motor cortex (MCx), and somatosensory cortex (SCx). TRPC5 mRNA expression was concentrated specifically in the deep layers 5/6 and superficial layers 2/3 of the PFC and anterior cingulate. Patch-clamp recording indicated a strong metabotropic glutamate-activated cation current-mediated depolarization that was dependent on intracellular Ca2+and inhibited by protein kinase C in brain regions associated with dense TRPC4 or 5 expression and absent in regions lacking TRPC4 and 5 expression. Overall, the dense corticolimbic expression pattern suggests that these Gq/PLC coupled nonselective cation channels may be involved in learning, memory, and goal-directed behaviors.
Health-Related Quality of Life and Overall Life Satisfaction in People with Serious Mental Illness
Amy L. Barnes,Meghan E. Murphy,Christopher A. Fowler,Melisa V. Rempfer
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/245103
Abstract: Quality of life (QoL) in people with schizophrenia and other serious mental illnesses (SMI) is an important outcome goal, yet there is no consistent definition of the construct. We examined three aspects of QoL in persons with SMI: overall life satisfaction, physical health-related QoL (HRQoL), and mental HRQoL. This study had two primary aims: first, to examine whether there are differences in physical and mental HRQoL in persons with SMI, and, second, to investigate the cognitive, clinical, and functional correlates of the three QoL indicators. Participants were 48 persons with SMI who completed assessments of QoL, cognition, functional capacity, psychiatric symptomatology, and medical comorbidity. Results indicate that participants experience similar levels of physical and mental HRQoL, and these two constructs are not related to one another. Physical HRQoL is associated with less medical comorbidity, while mental HRQoL is associated with negative and depressive symptoms. Overall life satisfaction was associated with fewer psychiatric symptoms and less medical comorbidity. This study adds to the important literature defining distinct domains of QoL and supports the necessity of addressing both physical and mental health factors as they relate to recovery and well-being among persons with SMI. 1. Introduction Quality of life (QoL) among persons with schizophrenia and other serious mental illnesses (SMI) has become an important outcome assessment for both research and treatment in recent years [1–4]. However, it remains unclear what factors best predict QoL in this population [3, 5, 6] and a significant challenge for researchers has been the varied methods used to define and measure the broad concept. In an attempt to reduce some of this heterogeneity, research in this area has begun to distinguish between objective and subjective assessments of QoL, as these appear to represent distinct constructs [6]. For instance, objective QoL has been operationalized by examining factors such as the frequency of social interactions, number of hours worked per week, or housing status [5]. However, subjective QoL measurement, which addresses perceived life satisfaction, may be a particularly meaningful treatment goal in this population [4] and is consistent with the recovery model, which emphasizes the lived experience of individuals with SMI [7, 8]. To date, much of the research on life satisfaction in SMI has focused on its relationship with cognitive and clinical symptoms. In terms of cognition, some studies have reported significant correlations between life
Generalized Random Simplicial Complexes
Christopher F. Fowler
Mathematics , 2015,
Abstract: We consider a multi-parameter model for randomly constructing simplicial complexes. This model interpolates between random clique complexes and Linial-Meshulam random $k$-dimensional complexes, two models that have been extensively studied. While these models asymptotically exhibit nontrivial cohomology in only one or two dimensions, we show that in this generalized setting nontrivial cohomology can occur in several dimensions simultaneously. We establish upper and lower thresholds for the appearance of nontrivial cohomology in a particular dimension, and in some instances characterize the behavior at criticality.
A long-term follow-up study investigating health-related quality of life and resource use in survivors of severe sepsis: comparison of recombinant human activated protein C with standard care
Christopher J Longo, Daren K Heyland, Harold N Fisher, Robert A Fowler, Claudio M Martin, Andrew G Day
Critical Care , 2008, DOI: 10.1186/cc7031
Abstract: Model based estimation for mean PCS and standard error bar for all patients. Average group differences: P = 0.04. APC, activated protein C; PCS, physical component score.Model based estimation for mean RP and standard error bar for all patients. Average group differences: P = 0.10. APC, activated protein C; RP, role physical.Model based estimation for mean BP and standard error bar for all patients. Average group differences: P = 0.14. APC, activated protein C; BP, bodily pain.Model based estimation for mean PF and standard error bar for all patients. Average group differences: P = 0.12. APC, activated protein C; PF, physical function.
A long-term follow-up study investigating health-related quality of life and resource use in survivors of severe sepsis: comparison of recombinant human activated protein C with standard care
Christopher J Longo, Daren K Heyland, Harold N Fisher, Robert A Fowler, Claudio M Martin, Andrew G Day
Critical Care , 2007, DOI: 10.1186/cc6195
Abstract: This was an observational cohort study at nine Canadian intensive care units. Patients with severe sepsis who survived to 28 days were recruited. Patients who received APC formed the treatment group and those that did not formed the standard care group. Patients who did not receive APC because of central nervous system bleeding risk were excluded from the standard care group. HRQoL (determined using the 36-item Short Form) and resource use were recorded at 28 days, and 3, 5 and 7 months.One hundred patients were enrolled (64 in the standard care group and 36 in the APC group), with 70 patients completing all follow-up visits. Over the 6 months of follow up, APC-treated patients exhibited statistically significantly better scores for the physical component score (P = 0.04) and trends toward improvements in physical functioning (P = 0.12), role physical (P = 0.10) and bodily pain (P = 0.14) as compared with standard care patients. Shorter hospital length of stay was observed for the APC group (36 days versus 48 days; P = 0.05).These findings challenge earlier assumptions suggesting equivalent HRQoL and resource use in APC-treated and standard care patients who survive severe sepsis.Each year approximately 750,000 patients in the USA develop sepsis, and at least 215,000 of these cases are fatal [1]. Several studies have documented that sepsis is associated with increased hospital resource utilization and prolonged intensive care unit (ICU) and hospital stay [2-5]. With such considerable effects on associated morbidity and mortality, the economic burden associated with sepsis has recently been estimated at 17 billion dollars each year in the USA alone [1]. As novel, expensive therapies for the treatment of sepsis are introduced into international markets, decision makers will need accurate estimates of long-term outcomes and resource utilization if they are to appreciate the relative merits and limitations of these new therapies.Morbidity associated with severe sepsis c
Comparison of percent density from raw and processed full-field digital mammography data
Celine M Vachon, Erin EE Fowler, Gail Tiffenberg, Christopher G Scott, V Shane Pankratz, Thomas A Sellers, John J Heine
Breast Cancer Research , 2013, DOI: 10.1186/bcr3372
Abstract: A case-control study of 180 cases and 180 controls matched by age, postmenopausal hormone use, and screening history was conducted. Mammograms were acquired from a General Electric Senographe 2000D FFDM unit. Percent density (PD) was assessed for each FFDM representation using the operator-assisted Cumulus method. Reproducibility within image type (n = 80) was assessed using Lin's concordance correlation coefficient (rc). Correlation of PD between image representations (n = 360) was evaluated using Pearson's correlation coefficient (r) on the continuous measures and the weighted kappa statistic (κ) for quartiles. Conditional logistic regression was used to estimate odds ratios (ORs) for the PD and breast cancer associations for both image representations with 95% confidence intervals. The area under the receiver operating characteristic curve (AUC) was used to assess the discriminatory accuracy.Percent density from the two representations provided similar intra-reader reproducibility (rc= 0.92 for raw and rc= 0.87 for processed images) and was correlated (r = 0.82 and κ = 0.64). When controlling for body mass index, the associations of quartiles of PD with breast cancer and discriminatory accuracy were similar for the raw (OR: 1.0 (ref.), 2.6 (1.2 to 5.4), 3.1 (1.4 to 6.8), 4.7 (2.1 to 10.6); AUC = 0.63) and processed representations (OR: 1.0 (ref.), 2.2 (1.1 to 4.1), 2.2 (1.1 to 4.4), 3.1 (1.5 to 6.6); AUC = 0.64).Percent density measured with an operator-assisted method from raw and processed FFDM images is reproducible and correlated. Both percent density measures provide similar associations with breast cancer.Increased mammographic breast density is an established breast cancer risk factor [1-3]. Irrespective of the method of measurement, the majority of studies have found a three- to sixfold increased risk of breast cancer in the highest vs. lowest density categories [2]. The majority of these studies estimated density from digitized film mammograms. Currently
Human Neuroepithelial Cells Express NMDA Receptors
Christopher D Sharp, M Fowler, TH Jackson, J Houghton, A Warren, A Nanda, I Chandler, B Cappell, A Long, A Minagar, JS Alexander
BMC Neuroscience , 2003, DOI: 10.1186/1471-2202-4-28
Abstract: Glutamate receptor stimulation is an important physiological event, which helps regulate learning and memory development. [1]. In the mammalian nervous system, L-glutamate binds to several classes of 'glutamatergic' receptors, which are classified into two major groups, metabotropic and ionotropic. Within the ionotropic family of glutamate receptors there are three subtypes (based upon their binding and activation by AMPA, kainic acid, and NMDA): 1) α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), 2) kainic acid (KA) receptors, and 3) N-methyl-D-aspartate (NMDA) receptors [2].Glutamate is present at concentrations ranging from 18–25 μM in plasma [3], 0.3 μM in the cerebral spinal fluid (CSF), and as high as 3 mM within the parenchymal cell stores [4-6]. However, under ischemic or traumatic conditions the glutamate concentration levels in the brain interstitial space can increase 55-fold [7] to levels that are toxic to neurons.During stroke and trauma it has been suggested that majority of glutamate released (although not the only pathway) is due to neuronal injury within the cerebrum, which is provoked by cerebral oxygen and glucose deprivation, resulting in the excessive release of stored synaptic glutamate. Glutamate synaptic release is due to the loss of ATP stores and dissipation of membrane ion gradients leads to K+ efflux, and membrane depolarization. Eventually anoxia triggers a massive depolarization and opening of voltage-dependent Na+ channels. As a result, glutamate is released by synaptic exocytosis and trapped in the interstitium, due to the reversal of the glutamate transporters flooding the synaptic space with glutamate. This response in turn leads to the massive over-stimulation of NMDA receptors, referred to as 'glutamate excitotoxicity' [8-11]. In addition to neuronal excitotoxicity, increased extracellular glutamate may also contribute to 'vasogenic edema' (characterized by an increase in microvascular solute permeability) [12-18].In the
Decreased Copper in Alzheimer’s Disease Brain Is Predominantly in the Soluble Extractable Fraction
Alan Rembach,Dominic J. Hare,Monica Lind,Christopher J. Fowler,Robert A. Cherny,Catriona McLean,Ashley I. Bush,Colin L. Masters,Blaine R. Roberts
International Journal of Alzheimer's Disease , 2013, DOI: 10.1155/2013/623241
Abstract: Alzheimer’s disease (AD) is the leading cause of dementia and represents a significant burden on the global economy and society. The role of transition metals, in particular copper (Cu), in AD has become of significant interest due to the dyshomeostasis of these essential elements, which can impart profound effects on cell viability and neuronal function. We tested the hypothesis that there is a systemic perturbation in Cu compartmentalization in AD, within the brain as well as in the periphery, specifically within erythrocytes. Our results showed that the previously reported decrease in Cu within the human frontal cortex was confined to the soluble ( ) and total homogenate ( ) fractions. No differences were observed in Cu concentration in erythrocytes. Our data indicate that there is a brain specific alteration in Cu levels in AD localized to the soluble extracted material, which is not reflected in erythrocytes. Further studies using metalloproteomics approaches will be able to elucidate the metabolic mechanism(s) that results in the decreased brain Cu levels during the progression of AD. 1. Introduction Alzheimer’s disease (AD) is the predominant cause of dementia in the aging population and represents a mounting health epidemic [1]. Despite advances in understanding the events leading to the onset of cognitive decline, the principal cause of AD is still undetermined. The role of copper (Cu), iron (Fe), and zinc (Zn) in AD has become of significant interest because the dyshomeostasis of essential trace elements has been observed to have profound effects on cell viability and neuronal function [2, 3], which have been previously reviewed [4]. Cu, an essential element in the central nervous system (CNS), is crucial for life, but its unique redox propensity renders it toxic in circumstances of an increase pool of labile species [5–8]. Specific lesions in the Cu pathway can lead to a severe but treatable neurological impairment, including Menkes and Wilson’s disease [9–11]. Cu displays a distinctly compartmentalized distribution throughout the brain, reflecting its diverse function in various neurological processes [12, 13]. Within the CNS, Cu is known to decrease in the frontal, occipital, and parietal lobes [14] amygdala and hippocampus in AD [15]. The process for this decline is not well understood, though extracellular plaques of aggregated amyloid-β (Aβ) are reported to be enriched with trace elements including Fe, Zn, and Cu [16]. Recently, it was also reported that frontal cortex from AD subjects had an increased propensity to bind exchangeable Cu,
Page 1 /471286
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.