2,315 research outputs found
Caenorhabditis elegans dnj-14, the orthologue of the DNAJC5 gene mutated in adult onset neuronal ceroid lipofuscinosis, provides a new platform for neuroprotective drug screening and identifies a SIR-2.1-independent action of resveratrol
Adult onset neuronal lipofuscinosis (ANCL) is a human neurodegenerative disorder characterized by progressive neuronal dysfunction and premature death. Recently, the mutations that cause ANCL were mapped to the DNAJC5 gene, which encodes cysteine string protein alpha. We show here that mutating dnj-14, the Caenorhabditis elegans orthologue of DNAJC5, results in shortened lifespan and a small impairment of locomotion and neurotransmission. Mutant dnj-14 worms also exhibited age-dependent neurodegeneration of sensory neurons, which was preceded by severe progressive chemosensory defects. A focussed chemical screen revealed that resveratrol could ameliorate dnj-14 mutant phenotypes, an effect mimicked by the cAMP phosphodiesterase inhibitor, rolipram. In contrast to other worm neurodegeneration models, activation of the Sirtuin, SIR-2.1, was not required, as sir-2.1; dnj-14 double mutants showed full lifespan rescue by resveratrol. The Sirtuin-independent neuroprotective action of resveratrol revealed here suggests potential therapeutic applications for ANCL and possibly other human neurodegenerative diseases
The what and where of adding channel noise to the Hodgkin-Huxley equations
One of the most celebrated successes in computational biology is the
Hodgkin-Huxley framework for modeling electrically active cells. This
framework, expressed through a set of differential equations, synthesizes the
impact of ionic currents on a cell's voltage -- and the highly nonlinear impact
of that voltage back on the currents themselves -- into the rapid push and pull
of the action potential. Latter studies confirmed that these cellular dynamics
are orchestrated by individual ion channels, whose conformational changes
regulate the conductance of each ionic current. Thus, kinetic equations
familiar from physical chemistry are the natural setting for describing
conductances; for small-to-moderate numbers of channels, these will predict
fluctuations in conductances and stochasticity in the resulting action
potentials. At first glance, the kinetic equations provide a far more complex
(and higher-dimensional) description than the original Hodgkin-Huxley
equations. This has prompted more than a decade of efforts to capture channel
fluctuations with noise terms added to the Hodgkin-Huxley equations. Many of
these approaches, while intuitively appealing, produce quantitative errors when
compared to kinetic equations; others, as only very recently demonstrated, are
both accurate and relatively simple. We review what works, what doesn't, and
why, seeking to build a bridge to well-established results for the
deterministic Hodgkin-Huxley equations. As such, we hope that this review will
speed emerging studies of how channel noise modulates electrophysiological
dynamics and function. We supply user-friendly Matlab simulation code of these
stochastic versions of the Hodgkin-Huxley equations on the ModelDB website
(accession number 138950) and
http://www.amath.washington.edu/~etsb/tutorials.html.Comment: 14 pages, 3 figures, review articl
Autism as a disorder of neural information processing: directions for research and targets for therapy
The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself
Molecular and cellular mechanisms underlying the evolution of form and function in the amniote jaw.
The amniote jaw complex is a remarkable amalgamation of derivatives from distinct embryonic cell lineages. During development, the cells in these lineages experience concerted movements, migrations, and signaling interactions that take them from their initial origins to their final destinations and imbue their derivatives with aspects of form including their axial orientation, anatomical identity, size, and shape. Perturbations along the way can produce defects and disease, but also generate the variation necessary for jaw evolution and adaptation. We focus on molecular and cellular mechanisms that regulate form in the amniote jaw complex, and that enable structural and functional integration. Special emphasis is placed on the role of cranial neural crest mesenchyme (NCM) during the species-specific patterning of bone, cartilage, tendon, muscle, and other jaw tissues. We also address the effects of biomechanical forces during jaw development and discuss ways in which certain molecular and cellular responses add adaptive and evolutionary plasticity to jaw morphology. Overall, we highlight how variation in molecular and cellular programs can promote the phenomenal diversity and functional morphology achieved during amniote jaw evolution or lead to the range of jaw defects and disease that affect the human condition
A search for the decay modes B+/- to h+/- tau l
We present a search for the lepton flavor violating decay modes B+/- to h+/-
tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472
million BBbar pairs. The search uses events where one B meson is fully
reconstructed in one of several hadronic final states. Using the momenta of the
reconstructed B, h, and l candidates, we are able to fully determine the tau
four-momentum. The resulting tau candidate mass is our main discriminant
against combinatorial background. We see no evidence for B+/- to h+/- tau l
decays and set a 90% confidence level upper limit on each branching fraction at
the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.
Evidence for an excess of B -> D(*) Tau Nu decays
Based on the full BaBar data sample, we report improved measurements of the
ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or
mu. These ratios are sensitive to new physics contributions in the form of a
charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) =
0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0
sigma and 2.7 sigma, respectively. Taken together, our results disagree with
these expectations at the 3.4 sigma level. This excess cannot be explained by a
charged Higgs boson in the type II two-Higgs-doublet model. We also report the
observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.Comment: Expanded section on systematics, text corrections, improved the
format of Figure 2 and included the effect of the change of the Tau
polarization due to the charged Higg
Study of the reaction e^{+}e^{-} -->J/psi\pi^{+}\pi^{-} via initial-state radiation at BaBar
We study the process with
initial-state-radiation events produced at the PEP-II asymmetric-energy
collider. The data were recorded with the BaBar detector at center-of-mass
energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454
. We investigate the mass
distribution in the region from 3.5 to 5.5 . Below 3.7
the signal dominates, and above 4
there is a significant peak due to the Y(4260). A fit to
the data in the range 3.74 -- 5.50 yields a mass value
(stat) (syst) and a width value (stat)(syst) for this state. We do not
confirm the report from the Belle collaboration of a broad structure at 4.01
. In addition, we investigate the system
which results from Y(4260) decay
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
A distinct bacterial dysbiosis associated skin inflammation in ovine footrot
Ovine footrot is a highly prevalent bacterial disease caused by Dichelobacter nodosus and characterised by the separation of the hoof horn from the underlying skin. The role of innate immune molecules and other bacterial communities in the development of footrot lesions remains unclear. This study shows a significant association between the high expression of IL1β and high D. nodosus load in footrot samples. Investigation of the microbial population identified distinct bacterial populations in the different disease stages and also depending on the level of inflammation. Treponema (34%), Mycoplasma (29%) and Porphyromonas (15%) were the most abundant genera associated with high levels of inflammation in footrot. In contrast, Acinetobacter (25%), Corynebacteria (17%) and Flavobacterium (17%) were the most abundant genera associated with high levels of inflammation in healthy feet. This demonstrates for the first time there is a distinct microbial community associated with footrot and high cytokine expression
'Collective Making' as knowledge mobilisation: the contribution of participatory design in the co-creation of knowledge in healthcare
The discourse in healthcare Knowledge Mobilisation (KMb) literature has shifted from simple, linear
models of research knowledge production and action to more iterative and complex models. These
aim to blend multiple stakeholders’ knowledge with research knowledge to address the researchpractice
gap. It has been suggested there is no 'magic bullet', but that a promising approach to take is
knowledge co-creation in healthcare, particularly if a number of principles are applied. These include
systems thinking, positioning research as a creative enterprise with human experience at its core, and
paying attention to process within the partnership. This discussion paper builds on this proposition
and extends it beyond knowledge co-creation to co-designing evidenced based interventions and
implementing them. Within a co-design model, we offer a specific approach to share, mobilise and
activate knowledge, that we have termed 'collective making'. We draw on KMb, design, wider
literature, and our experiences to describe how this framework supports and extends the principles of
co-creation offered by Geenhalgh et al[1] in the context of the state of the art of knowledge
mobilisation. We describe how collective making creates the right ‘conditions’ for knowledge to be
mobilised particularly addressing issues relating to stakeholder relationships, helps to discover, share
and blend different forms of knowledge from different stakeholders, and puts this blended
knowledge to practical use allowing stakeholders to learn about the practical implications of
knowledge use and to collectively create actionable products. We suggest this collective making has
three domains of influence: on the participants; on the knowledge discovered and shared; and on the
mobilisation or activation of this knowledge
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