1,236 research outputs found
Status report on TAUOLA, its environment, and its applications
The status of the Monte Carlo programs for the simulation of the tau-lepton
production and decay in high energy accelerator experiments is reviewed. In
particular, the status of the following packages is discussed: (i) TAUOLA for
tau-lepton decay and PHOTOS for radiative corrections in decays, (ii) MC-TESTER
for universal tests of the Monte Carlo programs describing particle decays,
(iii) KORALB, KORALZ, KKMC packages for tau-pair production in e+e- collisions,
and (iv) universal interface of TAUOLA for the decay of tau-leptons produced by
``any'' generator.Comment: Talk at the Seventh International Workshop on Tau Lepton Physics
(TAU02), Santa Cruz, Ca, USA, Sept 2002, 5 pages, LaTeX, 4 eps/ps figure
Covariant gauge fixing and Kuchar decomposition
The symplectic geometry of a broad class of generally covariant models is
studied. The class is restricted so that the gauge group of the models
coincides with the Bergmann-Komar group and the analysis can focus on the
general covariance. A geometrical definition of gauge fixing at the constraint
manifold is given; it is equivalent to a definition of a background (spacetime)
manifold for each topological sector of a model. Every gauge fixing defines a
decomposition of the constraint manifold into the physical phase space and the
space of embeddings of the Cauchy manifold into the background manifold (Kuchar
decomposition). Extensions of every gauge fixing and the associated Kuchar
decomposition to a neighbourhood of the constraint manifold are shown to exist.Comment: Revtex, 35 pages, no figure
Bacterial topoisomerase I as a target for discovery of antibacterial compounds
Bacterial topoisomerase I is a potential target for discovery of new antibacterial compounds. Mutant topoisomerases identified by SOS induction screening demonstrated that accumulation of the DNA cleavage complex formed by type IA topoisomerases is bactericidal. Characterization of these mutants of Yersinia pestis and Escherichia coli topoisomerase I showed that DNA religation can be inhibited while maintaining DNA cleavage activity by decreasing the binding affinity of Mg(II) ions. This can be accomplished either by mutation of the TOPRIM motif involved directly in Mg(II) binding or by altering the charge distribution of the active site region. Besides being used to elucidate the key elements for the control of the cleavage-religation equilibrium, the SOS-inducing mutants of Y. pestis and E. coli topoisomerase I have also been utilized as models to study the cellular response following the accumulation of bacterial topoisomerase I cleavage complex. Bacterial topoisomerase I is required for preventing hypernegative supercoiling of DNA during transcription. It plays an important role in transcription of stress genes during bacterial stress response. Topoisomerase I targeting poisons may be particularly effective when the bacterial pathogen is responding to host defense, or in the presence of other antibiotics that induce the bacterial stress response
Structural Coupling between RNA Polymerase Composition and DNA Supercoiling in Coordinating Transcription: a Global Role for the Omega Subunit?
In growing bacterial cells, the global reorganization of transcription is associated with alterations of RNA polymerase composition and the superhelical density of the DNA. However, the existence of any regulatory device coordinating these changes remains elusive. Here we show that in an exponentially growing Escherichia coli rpoZ mutant lacking the polymerase ω subunit, the impact of the Eσ38 holoenzyme on transcription is enhanced in parallel with overall DNA relaxation. Conversely, overproduction of σ70 in an rpoZ mutant increases both overall DNA supercoiling and the transcription of genes utilizing high negative superhelicity. We further show that transcription driven by the Eσ38 and Eσ70 holoenzymes from cognate promoters induces distinct superhelical densities of plasmid DNA in vivo. We thus demonstrate a tight coupling between polymerase holoenzyme composition and the supercoiling regimen of genomic transcription. Accordingly, we identify functional clusters of genes with distinct σ factor and supercoiling preferences arranging alternative transcription programs sustaining bacterial exponential growth. We propose that structural coupling between DNA topology and holoenzyme composition provides a basic regulatory device for coordinating genome-wide transcription during bacterial growth and adaptation
Hearing aid effectiveness after aural rehabilitation - individual versus group (HEARING) trial: RCT design and baseline characteristics
<p>Abstract</p> <p>Background</p> <p>Hearing impairment is the most common body system disability in veterans. In 2008, nearly 520,000 veterans had a disability for hearing loss through the Department of Veterans Affairs (VA). Changes in eligibility for hearing aid services, along with the aging population, contributed to a greater than 300% increase in the number of hearing aids dispensed from 1996 to 2006. In 2006, the VA committed to having no wait times for patient visits while providing quality clinically-appropriate care. One approach to achieving this goal is the use of group visits as an alternative to individual visits. We sought to determine: 1) if group hearing aid fitting and follow-up visits were at least as effective as individual visits, and 2) whether group visits lead to cost savings through the six month period after the hearing aid fitting. We describe the rationale, design, and characteristics of the baseline cohort of the first randomized clinical trial to study the impact of group versus individual hearing aid fitting and follow-up visits.</p> <p>Methods</p> <p>Participants were recruited from the VA Puget Sound Health Care System Audiology Clinic. Eligible patients had no previous hearing aid use and monaural or binaural air-conduction hearing aids were ordered at the evaluation visit. Participants were randomized to receive the hearing aid fitting and the hearing aid follow-up in an individual or group visit. The primary outcomes were hearing-related function, measured with the first module of the Effectiveness of Aural Rehabilitation (Inner EAR), and hearing aid adherence. We tracked the total cost of planned and unplanned audiology visits over the 6-month interval after the hearing aid fitting.</p> <p>Discussion</p> <p>A cohort of 659 participants was randomized to receive group or individual hearing aid fitting and follow-up visits. Baseline demographic and self-reported health status and hearing-related measures were evenly distributed across the treatment arms.</p> <p>Outcomes after the 6-month follow-up period are needed to determine if group visits were as least as good as those for individual visits and will be reported in subsequent publication.</p> <p>Trial Registration</p> <p>NCT00260663</p
ACR Appropriateness Criteria® Locoregional therapy for resectable oropharyngeal squamous cell carcinomas
BackgroundThere are no level I studies to guide treatment for resectable oropharyngeal squamous cell carcinoma (SCC). Treatment toxicities influence management recommendations. Ongoing investigations are examining deintensified treatments for human papillomavirus (HPV)‐associated oropharyngeal SCC.MethodsThe Appropriateness Criteria panel, using modified Delphi methodology, produced a literature summary, an assessment of treatment recommendations, and cases to illustrate their use.ResultsA multidisciplinary team produces optimum results. Based on HPV status, smoking history, and staging, patients are divided into groups at low, intermediate, and high‐risk of death. In the future, treatment recommendations may be influenced by HPV status, which has changed the epidemiology of oropharyngeal SCC.ConclusionT1 to T2N0M0 resectable oropharyngeal SCC can be treated with surgery or radiation without chemotherapy. Patients with T1‐2N1‐2aM0 disease can receive radiation, chemoradiation, or transoral surgery with neck dissection and appropriate adjuvant therapy. Patients with T1‐2N2b‐3M0 disease should receive chemoradiation or transoral surgery with neck dissection and appropriate adjuvant therapy. Concurrent chemoradiation is preferred for T3 to T4 disease. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1299–1309, 2016Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133590/1/hed24447.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133590/2/hed24447_am.pd
Downregulation of the Escherichia coli guaB promoter by FIS
The Escherichia coli guaB promoter (PguaB) regulates transcription of two genes, guaB and guaA, that are required for the synthesis of guanosine 5′-monophosphate (GMP), a precursor for the synthesis of guanine nucleoside triphosphates. Transcription from PguaB increases as a function of increasing cellular growth rate, and this is referred to as growth rate-dependent control (GRDC). Here we investigated the role of the factor for inversion stimulation (FIS) in the regulation of this promoter. The results showed that there are three binding sites for FIS centred near positions −11, +8 and +29 relative to the guaB transcription start site. Binding of FIS to these sites results in repression of PguaB in vitro but not in vivo. Deletion of the fis gene results in increased PguaB activity in vivo, but GRDC of PguaB is maintained
Imidazoquinolines with improved pharmacokinetic properties induce a high IFNα to TNFα ratio in vitro and in vivo
TLR Agonists have promising activity in preclinical models of viral infection and cancer. However, clinical use is only in topical application. Systemic uses of TLR-ligands such as Resiquimod, have failed due to adverse effects that limited dose and thus, efficacy. This issue could be related to pharmacokinetic properties that include fast elimination leading to low AUC with simultaneously high cmax at relevant doses. The high cmax is associated with a sharp, poorly tolerated cytokine pulse, suggesting that a compound with a higher AUC/cmax-ratio could provide a more sustained and tolerable immune activation. Our approach was to design TLR7/8-agonist Imidazoquinolines intended to partition to endosomes via acid trapping using a macrolide-carrier. This can potentially extend pharmacokinetics and simultaneously direct the compounds to the target compartment. The compounds have hTLR7/8-agonist activity (EC50 of the most active compound in cellular assays: 75-120 nM hTLR7, 2.8-3.1 µM hTLR8) and maximal hTLR7 activation between 40 and 80% of Resiquimod. The lead candidates induce secretion of IFNα from human Leukocytes in the same range as Resiquimod but induce at least 10-fold less TNFα in this system, consistent with a higher specificity for human TLR7. This pattern was reproduced in vivo in a murine system, where small molecules are thought not to activate TLR8. We found that Imidazoquinolines conjugated to a macrolide or, substances carrying an unlinked terminal secondary amine, had longer exposure compared with Resiquimod. The kinetics of pro-inflammatory cytokine release for these substances in vivo were slower and more extended (for comparable AUCs, approximately half-maximal plasma concentrations). Maximal IFNα plasma levels were reached 4 h post application. Resiquimod-treated groups had by then returned to baseline from a peak at 1 h. We propose that the characteristic cytokine profile is likely a consequence of altered pharmacokinetics and, potentially, enhanced endosomal tropism of the novel substances. In particular, our substances are designed to partition to cellular compartments where the target receptor and a distinct combination of signaling molecules relevant to IFNα-release are located. These properties could address the tolerability issues of TLR7/8 ligands and provide insight into approaches to fine-tune the outcomes of TLR7/8 activation by small molecules
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