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Search Results: 1 - 10 of 479675 matches for " Craig A James "
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More than Meets the Eye: Functionally Salient Changes in Internal Bone Architecture Accompany Divergence in Cichlid Feeding Mode
R. Craig Albertson,W. James Cooper,Kenneth A. Mann
International Journal of Evolutionary Biology , 2012, DOI: 10.1155/2012/538146
Abstract: African cichlids have undergone extensive and repeated adaptive radiations in foraging habitat. While the external morphology of the cichlid craniofacial skeleton has been studied extensively, biomechanically relevant changes to internal bone architecture have been largely overlooked. Here we explore two fundamental questions: (1) Do changes in the internal architecture of bone accompany shifts in foraging mode? (2) What is the genetic basis for this trait? We focus on the maxilla, which is an integral part of the feeding apparatus and an element that should be subjected to significant bending forces during biting. Analyses of CT scans revealed clear differences between the maxilla of two species that employ alternative foraging strategies (i.e., biting versus suction feeding). Hybrids between the two species exhibit maxillary geometries that closely resemble those of the suction feeding species, consistent with a dominant mode of inheritance. This was supported by the results of a genetic mapping experiment, where suction feeding alleles were dominant to biting alleles at two loci that affect bone architecture. Overall, these data suggest that the internal structure of the cichlid maxilla has a tractable genetic basis and that discrete shifts in this trait have accompanied the evolution of alternate feeding modes. 1. Introduction Adaptive radiations involve the concomitant evolution of ecological and phenotypic diversity within a rapidly multiplying lineage [1], and many of the most notable adaptive radiations are characterized by divergence in functional morphology. Hawaiian silverswords, for example, have evolved a suite of morphological traits associated with adaptations to an extreme range of environmental moisture (mesic to xeric) [2, 3]; Anolis lizards have diversified in regard to traits involved in clinging and climbing abilities [4–8]; both Galápagos finches and African cichlids are renowned for their extensive (and in the case of cichlids, repeated) adaptive radiations in trophic morphology that parallel, and presumably contribute to, microhabitat divergence in foraging niches [9–16]. Not surprisingly, considerable attention has been given to characterizing the phenotypic diversity associated with these extraordinary radiations [3, 4, 9, 14, 17–19]. In the case of the multiple adaptive radiations of East-African cichlids, extensive analyses of their anatomical diversity have only recently been undertaken [14, 20, 21]. Among the notable findings from this body of work is that patterns of diversification within each of the three large lakes in
β-alanine supplementation improves isometric endurance of the knee extensor muscles
Craig Sale, Chester A Hill, James Ponte, Roger C Harris
Journal of the International Society of Sports Nutrition , 2012, DOI: 10.1186/1550-2783-9-26
Abstract: Thirteen males (age 23?±?6 y; height 1.80?±?0.05?m; body mass 81.0?±?10.5?kg), matched for pre-supplementation isometric endurance, were allocated to either a placebo (n?=?6) or β-alanine (n?=?7; 6.4?g·d-1 over 4?weeks) supplementation group. Participants completed an isometric knee extension test (IKET) to fatigue, at an intensity of 45% MVIC, before and after supplementation. In addition, two habituation tests were completed in the week prior to the pre-supplementation test and a further practice test was completed in the week prior to the post-supplementation test. MVIC force, IKET hold-time, and impulse generated were recorded.IKET hold-time increased by 9.7?±?9.4?s (13.2%) and impulse by 3.7?±?1.3 kN·s-1 (13.9%) following β-alanine supplementation. These changes were significantly greater than those in the placebo group (IKET: t(11)?=?2.9, p ≤0.05; impulse: t(11)?=?3.1, p?≤?0.05). There were no significant changes in MVIC force in either group.Four weeks of β-alanine supplementation at 6.4?g·d-1 improved endurance capacity of the knee extensors at 45% MVIC, which most likely results from improved pH regulation within the muscle cell as a result of elevated muscle carnosine levels.
ErbB2 enhances mammary tumorigenesis, oncogene-independent recurrence and metastasis in a model of IGF-IR-mediated mammary tumorigenesis
Craig I Campbell, James J Petrik, Roger A Moorehead
Molecular Cancer , 2010, DOI: 10.1186/1476-4598-9-235
Abstract: ErbB2 was overexpressed in our RM11A cell line, a murine tumor cell line that overexpresses human IGF-IR in an inducible manner. ErbB2 conferred an accelerated tumor onset and increased tumor incidence after injection of RM11A cells into the mammary glands of syngeneic wild type mice. This was associated with increased proliferation immediately after tumor cell colonization of the mammary gland; however, this effect was lost after tumor establishment. ErbB2 overexpression also impaired the regression of established RM11A tumors following IGF-IR downregulation and enhanced their metastatic potential.This study has revealed that even in the presence of vast IGF-IR overexpression, a modest increase in ErbB2 can augment tumor establishment in vivo, mediate resistance to IGF-IR downregulation and facilitate metastasis. This supports the growing evidence suggesting a possible advantage of using IGF-IR and ErbB2-directed therapies concurrently in the treatment of breast cancer.Receptor tyrosine kinases (RTKs) are transmembrane proteins with intracellular kinase domains that undergo phosphorylation in response to ligand binding. This group of proteins has a well established role in breast cancer, and thus many RTKs are currently the focus of directed therapeutics with a significant number of these therapies in clinical trials. Two such proteins with validated roles in breast cancer are ErbB2 (also known as Her2/neu), a member of the epidermal growth factor receptor family, and the type I insulin-like growth factor receptor (IGF-IR). A large amount of evidence implicating both in clinical breast cancer is emerging. In addition, both receptors have been validated as oncogenes through the generation and characterization of transgenic mouse models (reviewed in [1] and [2]).The IGF-IR undergoes autophosphorylation on conserved intracellular tyrosine residues after binding its ligands IGF-I and IGF-II which subsequently triggers signal cascades involved in many processes includin
Modeling Grain Boundaries using a Phase Field Technique
Ryo Kobayashi,James A. Warren,W. Craig Carter
Physics , 1998,
Abstract: We propose a two dimensional frame-invariant phase field model of grain impingement and coarsening. One dimensional analytical solutions for a stable grain boundary in a bicrystal are obtained, and equilibrium energies are computed. We are able to calculate the rotation rate for a free grain between two grains of fixed orientation. For a particular choice of functional dependencies in the model the grain boundary energy takes the same analytic form as the microscopic (dislocation) model of Read and Shockley.
Clonal Interference, Multiple Mutations, and Adaptation in Large Asexual Populations
Craig A. Fogle,James L. Nagle,Michael M. Desai
Quantitative Biology , 2008,
Abstract: Two important problems affect the ability of asexual populations to accumulate beneficial mutations, and hence to adapt. First, clonal interference causes some beneficial mutations to be outcompeted by more-fit mutations which occur in the same genetic background. Second, multiple mutations occur in some individuals, so even mutations of large effect can be outcompeted unless they occur in a good genetic background which contains other beneficial mutations. In this paper, we use a Monte Carlo simulation to study how these two factors influence the adaptation of asexual populations. We find that the results depend qualitatively on the shape of the distribution of the effects of possible beneficial mutations. When this distribution falls off slower than exponentially, clonal interference alone reasonably describes which mutations dominate the adaptation, although it gives a misleading picture of the evolutionary dynamics. When the distribution falls off faster than exponentially, an analysis based on multiple mutations is more appropriate. Using our simulations, we are able to explore the limits of validity of both of these approaches, and we explore the complex dynamics in the regimes where neither are fully applicable.
Tissue Doppler imaging for diagnosis of coronary artery disease: a systematic review and meta-analysis
Rajender Agarwal, Priyanka Gosain, James N Kirkpatrick, Tareq Alyousef, Rami Doukky, Gurpreet Singh, Craig A Umscheid
Cardiovascular Ultrasound , 2012, DOI: 10.1186/1476-7120-10-47
Abstract: Coronary artery disease (CAD) is responsible for one out of every six deaths in the United States. Each year, approximately 800,000 Americans have a new coronary event resulting in approximately one death per minute [1]. This extraordinary burden of disease necessitates early diagnosis and treatment.Non-invasive imaging tests like radionuclide imaging and stress echocardiography are frequently used in clinical practice for detection and evaluation of CAD [2]. Global and regional left ventricular (LV) systolic function is an important marker of CAD in stress echocardiography, which is conventionally assessed using two-dimensional echocardiography. In 1989, the technique of tissue Doppler imaging (TDI) emerged as a potential modality for assessing systolic and diastolic LV performance [3-5]. TDI visualizes myocardial velocities by measuring low-frequency, high-amplitude signals of myocardial motion. TDI is done using either the spectral pulsed-wave or the color-coded pulsed-wave technique. Spectral Doppler measures the instantaneous velocity in a sample volume of the region of interest, while color-coded Doppler allows simultaneous sampling of the entire ultrasound sector [6-8].Most of the studies of TDI have employed the technique for measuring LV diastolic function. Other investigators have applied TDI to measure resting or post-stress velocities of various myocardial segments of the LV as an adjunct tool in the diagnosis of regional wall motion abnormalities from CAD. However, there has not been a consensus on the value of these techniques in the diagnosis of CAD. In this paper, we perform a systematic review and meta-analysis to assess the efficacy of TDI indices in the diagnosis of CAD.We searched MEDLINE (inception to June 2012) and the Cochrane Library (inception to June 2012) using keywords and/or medical subject headings (MeSH) for TDI and CAD. The detailed search strategy for MEDLINE is presented in Table 1. Titles and abstracts of the references identified
Quality of care for older adults with chronic obstructive pulmonary disease and asthma based on comparisons to practice guidelines and smoking status
Benjamin M Craig, Connie K Kraus, Betty A Chewning, James E Davis
BMC Health Services Research , 2008, DOI: 10.1186/1472-6963-8-144
Abstract: Using a nationally representative sample of 29,902 older adults who participated in the Medicare Current Beneficiary Survey (1992–2002), we compared guideline recommendations on the treatment and prevention of chronic obstructive pulmonary disease and asthma with survey utilization data, including the use of bronchodilators, spirometry and influenza vaccine.26% to 30% of older adults were diagnosed with or self-reported chronic respiratory diseases; however 69% received no pharmacological treatment and 30% of patients reporting use of pharmacological treatments did not receive short-acting bronchodilator inhalers. Current smokers appeared to receive significantly less care for respiratory diseases than non-smokers or former smokers.Disparities between recommended and actual care for older adults with chronic lung disease require further research. The needs of older adults with co-morbidities and nicotine addiction deserve special attention in care as well as guideline development and implementation.Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death of adults in the world and a leading cause of death in people over the age of 45 in the United States [1]. The worldwide prevalence in 1990 was estimated to be 9.34/1,000 in men and 7.33/1,000 in women, but these estimates included all ages and may have underestimated the true prevalence in older adults. COPD causes a major financial burden to the healthcare system [2]. Under-diagnosis and under-treatment are associated with increased use of emergency department services due to exacerbations of the disease [3]. Implementation of practice guidelines, optimization of pharmacotherapy and reduction of risk factors, like smoking, have been shown to improve clinical and economic outcomes.Likewise, asthma mortality continues to increase in the United States [4]. An analysis of asthma mortality between 1979 and 1996 showed that people over age 65 have the highest crude mortality rates from asthma. S
Open Babel: An open chemical toolbox
Noel M O'Boyle, Michael Banck, Craig A James, Chris Morley, Tim Vandermeersch, Geoffrey R Hutchison
Journal of Cheminformatics , 2011, DOI: 10.1186/1758-2946-3-33
Abstract: We discuss, for the first time, Open Babel, an open-source chemical toolbox that speaks the many languages of chemical data. Open Babel version 2.3 interconverts over 110 formats. The need to represent such a wide variety of chemical and molecular data requires a library that implements a wide range of cheminformatics algorithms, from partial charge assignment and aromaticity detection, to bond order perception and canonicalization. We detail the implementation of Open Babel, describe key advances in the 2.3 release, and outline a variety of uses both in terms of software products and scientific research, including applications far beyond simple format interconversion.Open Babel presents a solution to the proliferation of multiple chemical file formats. In addition, it provides a variety of useful utilities from conformer searching and 2D depiction, to filtering, batch conversion, and substructure and similarity searching. For developers, it can be used as a programming library to handle chemical data in areas such as organic chemistry, drug design, materials science, and computational chemistry. It is freely available under an open-source license from http://openbabel.org webcite.The history of chemical informatics has included a huge variety of textual and computer representations of molecular data. Such representations focus on specific atomic or molecular information and may not attempt to store all possible chemical data. For example, line notations like Daylight SMILES [1] do not offer coordinate information, while crystallographic or quantum mechanical formats frequently do not store chemical bonding data. Hydrogen atoms are frequently omitted from x-ray crystallography due to the difficulty in establishing coordinates, and are often ignored by some file formats as the "implicit valence" of heavy atoms that indicates their presence. Other types of representations require specification of atom types on the basis of a specific valence bond model, inclusion of c
MAP Kinase Phosphatase-2 Plays a Key Role in the Control of Infection with Toxoplasma gondii by Modulating iNOS and Arginase-1 Activities in Mice
Stuart Woods,Juliane Schroeder,Helen A. McGachy,Robin Plevin,Craig W. Roberts,James Alexander
PLOS Pathogens , 2013, DOI: 10.1371/journal.ppat.1003535
Abstract: The dual specific phosphatase, MAP kinase phosphatase-2 (MKP-2) has recently been demonstrated to negatively regulate macrophage arginase-1 expression, while at the same time to positively regulate iNOS expression. Consequently, MKP-2 is likely to play a significant role in the host interplay with intracellular pathogens. Here we demonstrate that MKP-2?/? mice on the C57BL/6 background have enhanced susceptibility compared with wild-type counterparts following infection with type-2 strains of Toxoplasma gondii as measured by increased parasite multiplication during acute infection, increased mortality from day 12 post-infection onwards and increased parasite burdens in the brain, day 30 post-infection. MKP-2?/? mice did not, however, demonstrate defective type-1 responses compared with MKP-2+/+ mice following infection although they did display significantly reduced serum nitrite levels and enhanced tissue arginase-1 expression. Early resistance to T. gondii in MKP-2+/+, but not MKP-2?/?, mice was nitric oxide (NO) dependent as infected MKP-2+/+, but not MKP-2?/? mice succumbed within 10 days post-infection with increased parasite burdens following treatment with the iNOS inhibitor L-NAME. Conversely, treatment of infected MKP-2?/? but not MKP-2+/+ mice with nor-NOHA increased parasite burdens indicating a protective role for arginase-1 in MKP-2?/? mice. In vitro studies using tachyzoite-infected bone marrow derived macrophages and selective inhibition of arginase-1 and iNOS activities confirmed that both iNOS and arginase-1 contributed to inhibiting parasite replication. However, the effects of arginase-1 were transient and ultimately the role of iNOS was paramount in facilitating long-term inhibition of parasite multiplication within macrophages.
Turning ABO$_3$ antiferroelectrics into ferroelectrics: Design rules for practical rotation-driven ferroelectricity in double perovskites and A$_3$B$_2$O$_7$ Ruddlesden-Popper compounds
Andrew T. Mulder,Nicole A. Benedek,James M. Rondinelli,Craig J. Fennie
Physics , 2012, DOI: 10.1002/adfm.201300210
Abstract: Ferroic transition metal oxides, which exhibit spontaneous elastic, electrical, magnetic or toroidal order, exhibit functional properties that find use in ultrastable solid-state memories to sensors and medical imaging technologies. To realize multifunctional behavior, where one order parameter can be coupled to the conjugate field of another order parameter, however, requires a common microscopic origin for the long-range order. Here, we formulate a complete theory for a novel form of ferroelectricity, whereby a spontaneous and switchable polarization emerges from the destruction of an antiferroelectric state due to octahedral rotations and ordered cation sublattices. We then construct a materials design framework based on crystal-chemistry descriptors rooted in group theory, which enables the facile design of artificial oxides with large electric polarizations, P, simultaneous with small energetic switching barriers between +P and -P. We validate the theory with first principles density functional calculations on more than 16 perovskite-structured oxides, illustrating it could be operative in any materials classes exhibiting two- or three-dimensional corner-connected octahedral frameworks. We show the principles governing materials selection of the "layered" systems originate in the lattice dynamics of the A cation displacements stabilized by the pervasive BO$_6$ rotations of single phase ABO$_3$ materials, whereby the latter distortions govern the optical band gaps, magnetic order and critical transition temperatures. Our approach provides the elusive route to the ultimate multifunctionality property control by an external electric field.
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