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Search Results: 1 - 10 of 147442 matches for " Aaron B Bowman "
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Disease-Toxicant Interactions in Manganese Exposed Huntington Disease Mice: Early Changes in Striatal Neuron Morphology and Dopamine Metabolism
Jennifer L. Madison, Michal Wegrzynowicz, Michael Aschner, Aaron B. Bowman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031024
Abstract: YAC128 Huntington's disease (HD) transgenic mice accumulate less manganese (Mn) in the striatum relative to wild-type (WT) littermates. We hypothesized that Mn and mutant Huntingtin (HTT) would exhibit gene-environment interactions at the level of neurochemistry and neuronal morphology. Twelve-week-old WT and YAC128 mice were exposed to MnCl2-4H2O (50 mg/kg) on days 0, 3 and 6. Striatal medium spiny neuron (MSN) morphology, as well as levels of dopamine (DA) and its metabolites (which are known to be sensitive to Mn-exposure), were analyzed at 13 weeks (7 days from initial exposure) and 16 weeks (28 days from initial exposure). No genotype-dependent differences in MSN morphology were apparent at 13 weeks. But at 16 weeks, a genotype effect was observed in YAC128 mice, manifested by an absence of the wild-type age-dependent increase in dendritic length and branching complexity. In addition, genotype-exposure interaction effects were observed for dendritic complexity measures as a function of distance from the soma, where only YAC128 mice were sensitive to Mn exposure. Furthermore, striatal DA levels were unaltered at 13 weeks by genotype or Mn exposure, but at 16 weeks, both Mn exposure and the HD genotype were associated with quantitatively similar reductions in DA and its metabolites. Interestingly, Mn exposure of YAC128 mice did not further decrease DA or its metabolites versus YAC128 vehicle exposed or Mn exposed WT mice. Taken together, these results demonstrate Mn-HD disease-toxicant interactions at the onset of striatal dendritic neuropathology in YAC128 mice. Our results identify the earliest pathological change in striatum of YAC128 mice as being between 13 to 16 weeks. Finally, we show that mutant HTT suppresses some Mn-dependent changes, such as decreased DA levels, while it exacerbates others, such as dendritic pathology.
Lipid Modifications of Sonic Hedgehog Ligand Dictate Cellular Reception and Signal Response
Vandana K. Grover,J. Gerardo Valadez,Aaron B. Bowman,Michael K. Cooper
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021353
Abstract: Sonic hedgehog (Shh) signaling regulates cell growth during embryonic development, tissue homeostasis and tumorigenesis. Concentration-dependent cellular responses to secreted Shh protein are essential for tissue patterning. Shh ligand is covalently modified by two lipid moieties, cholesterol and palmitate, and their hydrophobic properties are known to govern the cellular release and formation of soluble multimeric Shh complexes. However, the influences of the lipid moieties on cellular reception and signal response are not well understood.
Glutamine-Expanded Ataxin-7 Alters TFTC/STAGA Recruitment and Chromatin Structure Leading to Photoreceptor Dysfunction
Dominique Helmlinger,Sara Hardy,Gretta Abou-Sleymane,Adrien Eberlin,Aaron B. Bowman,Anne Gansmüller,Serge Picaud,Huda Y. Zoghbi,Yvon Trottier,Làszlò Tora,Didier Devys
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0040067
Abstract: Spinocerebellar ataxia type 7 (SCA7) is one of several inherited neurodegenerative disorders caused by a polyglutamine (polyQ) expansion, but it is the only one in which the retina is affected. Increasing evidence suggests that transcriptional alterations contribute to polyQ pathogenesis, although the mechanism is unclear. We previously demonstrated that theSCA7 gene product, ataxin-7 (ATXN7), is a subunit of the GCN5 histone acetyltransferase–containing coactivator complexes TFTC/STAGA. We show here that TFTC/STAGA complexes purified from SCA7 mice have normal TRRAP, GCN5, TAF12, and SPT3 levels and that their histone or nucleosomal acetylation activities are unaffected. However, rod photoreceptors from SCA7 mouse models showed severe chromatin decondensation. In agreement, polyQ-expanded ataxin-7 induced histone H3 hyperacetylation, resulting from an increased recruitment of TFTC/STAGA to specific promoters. Surprisingly, hyperacetylated genes were transcriptionally down-regulated, and expression analysis revealed that nearly all rod-specific genes were affected, leading to visual impairment in SCA7 mice. In conclusion, we describe here a set of events accounting for SCA7 pathogenesis in the retina, in which polyQ-expanded ATXN7 deregulated TFTC/STAGA recruitment to a subset of genes specifically expressed in rod photoreceptors, leading to chromatin alterations and consequent progressive loss of rod photoreceptor function.
Gammaretroviral vector encoding a fluorescent marker to facilitate detection of reprogrammed human fibroblasts during iPSC generation
Narasimhachar Srinivasakumar,Michail Zaboikin,Andrew M. Tidball,Asad A. Aboud,M. Diana Neely,Kevin C. Ess,Aaron B. Bowman,Friedrich G. Schuening
PeerJ , 2015, DOI: 10.7717/peerj.224
Abstract: Induced pluripotent stem cells (iPSCs) are becoming mainstream tools to study mechanisms of development and disease. They have a broad range of applications in understanding disease processes, in vitro testing of novel therapies, and potential utility in regenerative medicine. Although the techniques for generating iPSCs are becoming more straightforward, scientists can expend considerable resources and time to establish this technology. A major hurdle is the accurate determination of valid iPSC-like colonies that can be selected for further cloning and characterization. In this study, we describe the use of a gammaretroviral vector encoding a fluorescent marker, mRFP1, to not only monitor the efficiency of initial transduction but also to identify putative iPSC colonies through silencing of mRFP1 gene as a consequence of successful reprogramming.
Towards a National Injury Costing System?:Lessons from a Public-Private Injury Costing Pilot Study in South Africa
G Stevens, B Bowman
African Safety Promotion: A Journal of Injury and Violence Prevention , 2009,
Abstract: South Africa has extremely high incidence rates of fatal and non-fatal injuries due to interpersonal violence, pedestrian–motor vehicle collisions, burns, falls and other unintentional causes. While the actual cost associated with these injuries remains relatively unknown, the estimated direct cost of the medical treatment, rehabilitation and administration of these victims may run into billions of rands. This public–private injury costing pilot study (hereafter the study) was conducted at a tertiary public health facility in Johannesburg, South Africa (hereafter the public facility). The study attempted to facilitate further costing capacity through skills transfers from personnel at a sentinel private health facility in Johannesburg (hereafter the private hospital) to selected personnel within the identified public facility, and through the determination of the partial baseline direct medical cost of the treatment of gun shot wounds, pedestrian–motor vehicle collision injuries, falls and burns at the public facility. Both the capacity building component and the actual study were complicated by a number of obstacles, including limited personnel, poor costing and billing capacity, underdeveloped billing documentation and recording procedures, and limited levels of investment in the general practice of injury costing in the public health sector itself. This article examines the practical challenges facing further attempts to describe the cost of injuries in South Africa. It concludes with several critical reflections on concerns associated with an uncritical pursuit of the roll-out of a national injury costing system, which may have a negative impact on service delivery to the very populations that encounter injuries as a public health sector priority.
Research and Theory Towards a National Injury Costing System?:Lessons from a Public-Private Injury Costing Pilot Study in South Africa
G Stevens, B Bowman
African Safety Promotion: A Journal of Injury and Violence Prevention , 2009,
Abstract: South Africa has extremely high incidence rates of fatal and non-fatal injuries due to interpersonal violence, pedestrian–motor vehicle collisions, burns, falls and other unintentional causes. While the actual cost associated with these injuries remains relatively unknown, the estimated direct cost of the medical treatment, rehabilitation and administration of these victims may run into billions of rands. This public–private injury costing pilot study (hereafter the study) was conducted at a tertiary public health facility in Johannesburg, South Africa (hereafter the public facility). The study attempted to facilitate further costing capacity through skills transfers from personnel at a sentinel private health facility in Johannesburg (hereafter the private hospital) to selected personnel within the identified public facility, and through the determination of the partial baseline direct medical cost of the treatment of gun shot wounds, pedestrian–motor vehicle collision injuries, falls and burns at the public facility. Both the capacity building component and the actual study were complicated by a number of obstacles, including limited personnel, poor costing and billing capacity, underdeveloped billing documentation and recording procedures, and limited levels of investment in the general practice of injury costing in the public health sector itself. This article examines the practical challenges facing further attempts to describe the cost of injuries in South Africa. It concludes with several critical reflections on concerns associated with an uncritical pursuit of the roll-out of a national injury costing system, which may have a negative impact on service delivery to the very populations that encounter injuries as a public health sector priority.
Glutamine-Expanded Ataxin-7 Alters TFTC/STAGA Recruitment and Chromatin Structure Leading to Photoreceptor Dysfunction
Dominique Helmlinger,Sara Hardy equal contributor,Gretta Abou-Sleymane equal contributor,Adrien Eberlin,Aaron B Bowman,Anne Gansmüller,Serge Picaud,Huda Y Zoghbi,Yvon Trottier,Làszlò Tora ,Didier Devys
PLOS Biology , 2006, DOI: 10.1371/journal.pbio.0040067
Abstract: Spinocerebellar ataxia type 7 (SCA7) is one of several inherited neurodegenerative disorders caused by a polyglutamine (polyQ) expansion, but it is the only one in which the retina is affected. Increasing evidence suggests that transcriptional alterations contribute to polyQ pathogenesis, although the mechanism is unclear. We previously demonstrated that theSCA7 gene product, ataxin-7 (ATXN7), is a subunit of the GCN5 histone acetyltransferase–containing coactivator complexes TFTC/STAGA. We show here that TFTC/STAGA complexes purified from SCA7 mice have normal TRRAP, GCN5, TAF12, and SPT3 levels and that their histone or nucleosomal acetylation activities are unaffected. However, rod photoreceptors from SCA7 mouse models showed severe chromatin decondensation. In agreement, polyQ-expanded ataxin-7 induced histone H3 hyperacetylation, resulting from an increased recruitment of TFTC/STAGA to specific promoters. Surprisingly, hyperacetylated genes were transcriptionally down-regulated, and expression analysis revealed that nearly all rod-specific genes were affected, leading to visual impairment in SCA7 mice. In conclusion, we describe here a set of events accounting for SCA7 pathogenesis in the retina, in which polyQ-expanded ATXN7 deregulated TFTC/STAGA recruitment to a subset of genes specifically expressed in rod photoreceptors, leading to chromatin alterations and consequent progressive loss of rod photoreceptor function.
An experimental-differential investigation of cognitive complexity
DAMIAN P. BIRNEY,DAVID B. BOWMAN
Psychology Science Quarterly , 2009,
Abstract: Cognitive complexity as defined by differential and experimental traditions was explored to investigate the theoretical advantage and utility of relational complexity (RC) theory as a common framework for studying fluid cognitive functions. RC theory provides a domain general account of processing demand as a function of task complexity. In total, 142 participants completed two tasks in which RC was manipulated, and two tasks entailing manipulations of complexity derived from the differential psychology literature. A series of analyses indicated that, as expected, task manipulations influenced item difficulty. However, comparable changes in a psychometric index of complexity were not consistently observed. Active maintenance of information across multiple steps of the problem solving process, which entails strategic coordination of storage and processing that cannot be modelled under the RC framework was found to be an important component of cognitive complexity.
Measuring perinatal complications: methodologic issues related to gestational age
Aaron B Caughey
BMC Pregnancy and Childbirth , 2007, DOI: 10.1186/1471-2393-7-18
Abstract: One issue that can clearly affect absolute rates and trends is how groups of women are categorized by their gestational age. Since most perinatal outcomes can only occur in women and neonates who have delivered, using the number of pregnancies delivered (PD) as the denominator of outcomes is appropriate. However, for an outcome such as antepartum stillbirth, all women who are pregnant at a particular gestational age are at risk. Thus, the denominator should include all ongoing pregnancies (OP). When gestational age is used by week this means using both deliveries during a particular week plus those women who deliver beyond the particular week of gestation in the denominator. Researchers should be careful to make sure they are utilizing the appropriate measure of perinatal complications so they do not report findings that would be misleading to clinicians, patients, and policy makers.Traditional perinatal epidemiology utilized metrics such as the neonatal mortality rate (number of neonatal deaths per 1,000 live births) and the perinatal mortality rate (number of neonatal deaths plus stillbirths per 1,000 total births) [1]. Prior to the current age of birth certificate and other large electronic databases, expanding computational power, and statistical software packages, it was recognized that these simple metrics had some small problems, but gave reasonable estimates to compare risk factors. While much of the technological advances have led to better statistical techniques for controlling potential confounders and quicker analysis of large data files, there has been little attempt to develop appropriate metrics to examine rates of perinatal morbidity and mortality and to further improve the accuracy of these measures. This is unfortunate, as the thoughtful approach to measuring complications of pregnancy is paramount and different methods can lead to entirely different outcomes and conclusions.For example, when examining the complications among all patients with term
Acute Gamma Hydroxybutyrate Toxicity
Schneir, Aaron B
Western Journal of Emergency Medicine : Integrating Emergency Care with Population Health , 2001,
Abstract:
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