644 research outputs found
A Review of Generalist and Specialist Community Health Workers for Delivering Adolescent Health Services in sub-Saharan Africa.
The health of adolescents is increasingly seen as an important international priority because the world's one point eight billion young people (aged 10 to 24 years) accounts for 15.5% of the global burden of disease and are disproportionately located in low- and middle-income countries (LMICs). Furthermore, an estimated 70% of premature adult deaths are attributable to unhealthy behaviors often initiated in adolescence (such as smoking, obesity, and physical inactivity). In order for health services to reach adolescents in LMICs, innovative service delivery models need to be explored and tested. This paper reviews the literature on generalist and specialist community health workers (CHWs) to assess their potential for strengthening the delivery of adolescent health services. We reviewed the literature on CHWs using Medline (PubMed), EBSCO Global Health, and Global Health Archive. Search terms (n = 19) were sourced from various review articles and combined with subject heading 'sub-Saharan Africa' to identify English language abstracts of original research articles on generalist and specialist CHWs. A total of 106 articles, from 1985 to 2012, and representing 24 African countries, matched our search criteria. A single study in sub-Saharan Africa used CHWs to deliver adolescent health services with promising results. Though few comprehensive evaluations of large-scale CHW programs exist, we found mixed evidence to support the use of either generalist or specialist CHW models for delivering adolescent health services. This review found that innovative service delivery approaches, such as those potentially offered by CHWs, for adolescents in sub-Saharan Africa are lacking, CHW programs have proliferated despite the absence of high quality evaluations, rigorous studies to establish the comparative effectiveness of generalist versus specialist CHW programs are needed, and further investigation of the role of CHWs in providing adolescent health services in sub-Saharan Africa is warranted
A New Discriminator for Gamma-Ray Burst Classification: The Epeak-Fluence Energy Ratio
Using the derived gamma-ray burst E_peak and fluences from the complete BATSE
5B Spectral Catalog, we study the ensemble characteristics of the
E_peak-fluence relation for GRBs. This relation appears to be a physically
meaningful and insightful fundamental discriminator between long and short
bursts. We discuss the results of the lower limit test of the E_peak-E_iso
relations in the E_peak-fluence plane for BATSE bursts with no observed
redshift. Our results confirm the presence of two GRB classes as well as
heavily suggesting two different GRB progenitor types.Comment: 8 pages, 3 figures, accepted for publication in Ap
WATCHING NEURONS GROW: GUIDANCE RECEPTORS, SIGNAL TRANSDUCTION MACHINERY AND CYTOSKELETAL REGULATORS AFFECT GROWTH CONE MORPHOLOGY AND DYNAMICS IN C. ELEGANS
The growth cone of a developing axon senses and responds to extracellular cues resulting in the migration of the growth cone and thus the axon to the correct target in the nervous system. Growth cones display dynamic, actin-based filopodial and lamellipodial protrusions. While much work has been done on growth cones in vitro and on fully developed axons in vivo, little has been done to study growth cones in vivo as the organism is developing. This work aims to bridge that gap by using C. elegans as a model system to study in vivo growth cone development. We found that many genes important for proper axon guidance exert their activity on the growth cone. We found a series of actin-modulating proteins important for filopodia formation, a guidance cue and its receptors important for polarity and extent of both filopodial and lammelipodial protrusion, and a pathway of signal transduction proteins and cytoskeletal regulators important for limiting the extent of filopodial protrusion. We show that in each of these cases, the proper control of growth cone morphology was important for the final axon pathfinding outcome. This work bridges the gap between in vitro growth cone analysis and in vivo endpoint analysis, showing a link between developmental control over protrusion and correct axon pathfinding and nervous system development
The Arp2/3 Complex, UNC-115/abLIM, and UNC-34/Enabled Regulate Axon Guidance and Growth Cone Filopodia Formation in Caenorhabditis Elegans
Background
While many molecules involved in axon guidance have been identified, the cellular and molecular mechanisms by which these molecules regulate growth cone morphology during axon outgrowth remain to be elucidated. The actin cytoskeleton of the growth cone underlies the formation of lamellipodia and filopodia that control growth cone outgrowth and guidance. The role of the Arp2/3 complex in growth cone filopodia formation has been controversial, and other mechanisms of growth cone filopodia formation remain to be described.
Results
Here we show that mutations in genes encoding the Arp2/3 complex (arx genes) caused defects in axon guidance. Analysis of developing growth cones in vivo showed that arx mutants displayed defects in filopodia and reduced growth cone size. Time-lapse analysis of growth cones in living animals indicated that arx mutants affected the rate of growth cone filopodia formation but not filopodia stability or length. Two other actin modulatory proteins, UNC-115/abLIM and UNC-34/Enabled, that had been shown previously to affect axon guidance had overlapping roles with Arp2/3 in axon guidance and also affected the rate of filopodia initiation but not stability or length.
Conclusion
Our results indicate that the Arp2/3 complex is required cell-autonomously for axon guidance and growth cone filopodia initiation. Furthermore, they show that two other actin-binding proteins, UNC-115/abLIM and UNC-34/Enabled, also control growth cone filopodia formation, possibly in parallel to Arp2/3. These studies indicate that, in vivo, multiple actin modulatory pathways including the Arp2/3 complex contribute to growth cone filopodia formation during growth cone outgrowth
The Arp2/3 complex, UNC-115/abLIM, and UNC-34/Enabled regulate axon guidance and growth cone filopodia formation in Caenorhabditis elegans
<p>Abstract</p> <p>Background</p> <p>While many molecules involved in axon guidance have been identified, the cellular and molecular mechanisms by which these molecules regulate growth cone morphology during axon outgrowth remain to be elucidated. The actin cytoskeleton of the growth cone underlies the formation of lamellipodia and filopodia that control growth cone outgrowth and guidance. The role of the Arp2/3 complex in growth cone filopodia formation has been controversial, and other mechanisms of growth cone filopodia formation remain to be described.</p> <p>Results</p> <p>Here we show that mutations in genes encoding the Arp2/3 complex (<it>arx </it>genes) caused defects in axon guidance. Analysis of developing growth cones <it>in vivo </it>showed that <it>arx </it>mutants displayed defects in filopodia and reduced growth cone size. Time-lapse analysis of growth cones in living animals indicated that <it>arx </it>mutants affected the rate of growth cone filopodia formation but not filopodia stability or length. Two other actin modulatory proteins, UNC-115/abLIM and UNC-34/Enabled, that had been shown previously to affect axon guidance had overlapping roles with Arp2/3 in axon guidance and also affected the rate of filopodia initiation but not stability or length.</p> <p>Conclusion</p> <p>Our results indicate that the Arp2/3 complex is required cell-autonomously for axon guidance and growth cone filopodia initiation. Furthermore, they show that two other actin-binding proteins, UNC-115/abLIM and UNC-34/Enabled, also control growth cone filopodia formation, possibly in parallel to Arp2/3. These studies indicate that, <it>in vivo</it>, multiple actin modulatory pathways including the Arp2/3 complex contribute to growth cone filopodia formation during growth cone outgrowth.</p
The UNC-6/Netrin receptors UNC-40/DCC and UNC-5 inhibit growth cone filopodial protrusion via UNC-73/Trio, Rac-like GTPases and UNC-33/CRMP
UNC-6/Netrin is a conserved axon guidance cue that can mediate both attraction and repulsion. We previously discovered that attractive UNC-40/DCC receptor signaling stimulates growth cone filopodial protrusion and that repulsive UNC-40–UNC-5 heterodimers inhibit filopodial protrusion in C. elegans. Here, we identify cytoplasmic signaling molecules required for UNC-6-mediated inhibition of filopodial protrusion involved in axon repulsion. We show that the Rac-like GTPases CED-10 and MIG-2, the Rac GTP exchange factor UNC-73/Trio, UNC-44/Ankyrin and UNC-33/CRMP act in inhibitory UNC-6 signaling. These molecules were required for the normal limitation of filopodial protrusion in developing growth cones and for inhibition of growth cone filopodial protrusion caused by activated MYR::UNC-40 and MYR::UNC-5 receptor signaling. Epistasis studies using activated CED-10 and MIG-2 indicated that UNC-44 and UNC-33 act downstream of the Rac-like GTPases in filopodial inhibition. UNC-73, UNC-33 and UNC-44 did not affect the accumulation of full-length UNC-5::GFP and UNC-40::GFP in growth cones, consistent with a model in which UNC-73, UNC-33 and UNC-44 influence cytoskeletal function during growth cone filopodial inhibition.We thank E. Struckhoff for technical assistance and J. Culotti for kindly providing the pU5GFP plasmid. Some strains were provided by the CGC, which is funded by the NIH Office of Research Infrastructure Programs [P40OD010440]
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas Reservoirs
We present the H i mass inventory for the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey, a volume-limited, multi-wavelength census of >1500 z = 0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of ~109 . This first 21 cm data release provides robust detections or strong upper limits (1.4M H i 1012 ) halos, suggesting that gas stripping and/or starvation may be induced by interactions with larger halos or the surrounding cosmic web. We find that the detailed relationship between G/S and environment varies when we examine different subvolumes of RESOLVE independently, which we suggest may be a signature of assembly bias
Early Stage Drug Treatment that Normalizes Proinflammatory Cytokine Production Attenuates Synaptic Dysfunction in a Mouse Model that Exhibits Age-Dependent Progression of Alzheimer\u27s Disease-Related Pathology
Overproduction of proinflammatory cytokines in the CNS has been implicated as a key contributor to pathophysiology progression in Alzheimer\u27s disease (AD), and extensive studies with animal models have shown that selective suppression of excessive glial proinflammatory cytokines can improve neurologic outcomes. The prior art, therefore, raises the logical postulation that intervention with drugs targeting dysregulated glial proinflammatory cytokine production might be effective disease-modifying therapeutics if used in the appropriate biological time window. To test the hypothesis that early stage intervention with such drugs might be therapeutically beneficial, we examined the impact of intervention with MW01-2-151SRM (MW-151), an experimental therapeutic that selectively attenuates proinflammatory cytokine production at low doses. MW-151 was tested in an APP/PS1 knock-in mouse model that exhibits increases in AD-relevant pathology progression with age, including increases in proinflammatory cytokine levels. Drug was administered during two distinct but overlapping therapeutic time windows of early stage pathology development. MW-151 treatment attenuated the increase in microglial and astrocyte activation and proinflammatory cytokine production in the cortex and yielded improvement in neurologic outcomes, such as protection against synaptic protein loss and synaptic plasticity impairment. The results also demonstrate that the therapeutic time window is an important consideration in efficacy studies of drugs that modulate glia biological responses involved in pathology progression and suggest that such paradigms should be considered in the development of new therapeutic regimens that seek to delay the onset or slow the progression of AD
Targeting Astrocytes Ameliorates Neurologic Changes in a Mouse Model of Alzheimer\u27s Disease
Astrocytes are the most abundant cell type in the brain and play a critical role in maintaining healthy nervous tissue. In Alzheimer\u27s disease (AD) and most other neurodegenerative disorders, many astrocytes convert to a chronically activated phenotype characterized by morphologic and biochemical changes that appear to compromise protective properties and/or promote harmful neuroinflammatory processes. Activated astrocytes emerge early in the course of AD and become increasingly prominent as clinical and pathological symptoms progress, but few studies have tested the potential of astrocyte-targeted therapeutics in an intact animal model of AD. Here, we used adeno-associated virus (AAV) vectors containing the astrocyte-specific Gfa2 promoter to target hippocampal astrocytes in APP/PS1 mice. AAV-Gfa2 vectors drove the expression of VIVIT, a peptide that interferes with the immune/inflammatory calcineurin/NFAT (nuclear factor of activated T-cells) signaling pathway, shown by our laboratory and others to orchestrate biochemical cascades leading to astrocyte activation. After several months of treatment with Gfa2-VIVIT, APP/PS1 mice exhibited improved cognitive and synaptic function, reduced glial activation, and lower amyloid levels. The results confirm a deleterious role for activated astrocytes in AD and lay the groundwork for exploration of other novel astrocyte-based therapies
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