220 research outputs found
Structural determinants of oligomerization of the aquaporin-4 channel
��2016 by The American Society for Biochemistry and Molecular Biology, Inc. The aquaporin (AQP) family of integral membrane protein channels mediate cellular water and solute flow. Although qualitative and quantitative differences in channel permeability, selectivity, subcellular localization, and trafficking responses have been observed for different members of the AQP family, the signature homotetrameric quaternary structure is conserved. Using a variety of biophysical techniques, we show that mutations to an intracellular loop (loop D) of human AQP4 reduce oligomerization. Non-tetrameric AQP4 mutants are unable to relocalize to the plasma membrane in response to changes in extracellular tonicity, despite equivalent constitutive surface expression levels and water permeability to wild-type AQP4. A network of AQP4 loop D hydrogen bonding interactions, identified using molecular dynamics simulations and based on a comparative mutagenic analysis of AQPs 1, 3, and 4, suggest that loop D interactions may provide a general structural framework for tetrameric assembly within theAQPfamily.Supported by Biotechnology and Biological Sciences Research Council Grants BB/I019960/1, BB/K013319/1, and BB/L502194/1 and Innovative Medicines Joint Undertaking under Grant Agreement 115583 to the ND4BB ENABLE Consortium.Published versio
Methylated DNA recognition during the reversal of epigenetic silencing is regulated by cysteine and cerine residues in the Epstein-Barr Virus lytic switch protein
Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with various malignancies, including Burkitt's lymphoma and nasopharyngeal carcinoma. Like all herpesviruses, the EBV life cycle alternates between latency and lytic replication. During latency, the viral genome is largely silenced by host-driven methylation of CpG motifs and, in the switch to the lytic cycle, this epigenetic silencing is overturned. A key event is the activation of the viral BRLF1 gene by the immediate-early protein Zta. Zta is a bZIP transcription factor that preferentially binds to specific response elements (ZREs) in the BRLF1 promoter (Rp) when these elements are methylated. Zta's ability to trigger lytic cycle activation is severely compromised when a cysteine residue in its bZIP domain is mutated to serine (C189S), but the molecular basis for this effect is unknown. Here we show that the C189S mutant is defective for activating Rp in a Burkitt's lymphoma cell line. The mutant is compromised both in vitro and in vivo for binding two methylated ZREs in Rp (ZRE2 and ZRE3), although the effect is striking only for ZRE3. Molecular modeling of Zta bound to methylated ZRE3, together with biochemical data, indicate that C189 directly contacts one of the two methyl cytosines within a specific CpG motif. The motif's second methyl cytosine (on the complementary DNA strand) is predicted to contact S186, a residue known to regulate methyl-ZRE recognition. Our results suggest that C189 regulates the enhanced interaction of Zta with methylated DNA in overturning the epigenetic control of viral latency. As C189 is conserved in many bZIP proteins, the selectivity of Zta for methylated DNA may be a paradigm for a more general phenomenon
QueryVis: Logic-based diagrams help users understand complicated SQL queries faster
Understanding the meaning of existing SQL queries is critical for code
maintenance and reuse. Yet SQL can be hard to read, even for expert users or
the original creator of a query. We conjecture that it is possible to capture
the logical intent of queries in \emph{automatically-generated visual diagrams}
that can help users understand the meaning of queries faster and more
accurately than SQL text alone. We present initial steps in that direction with
visual diagrams that are based on the first-order logic foundation of SQL and
can capture the meaning of deeply nested queries. Our diagrams build upon a
rich history of diagrammatic reasoning systems in logic and were designed using
a large body of human-computer interaction best practices: they are
\emph{minimal} in that no visual element is superfluous; they are
\emph{unambiguous} in that no two queries with different semantics map to the
same visualization; and they \emph{extend} previously existing visual
representations of relational schemata and conjunctive queries in a natural
way. An experimental evaluation involving 42 users on Amazon Mechanical Turk
shows that with only a 2--3 minute static tutorial, participants could
interpret queries meaningfully faster with our diagrams than when reading SQL
alone. Moreover, we have evidence that our visual diagrams result in
participants making fewer errors than with SQL. We believe that more regular
exposure to diagrammatic representations of SQL can give rise to a
\emph{pattern-based} and thus more intuitive use and re-use of SQL. All details
on the experimental study, the evaluation stimuli, raw data, and analyses, and
source code are available at https://osf.io/mycr2Comment: Full version of paper appearing in SIGMOD 202
The extraordinary evolutionary history of the reticuloendotheliosis viruses
The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVsâunequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events
Effects of Methoxyisoflavone, Ecdysterone, and Sulfo-Polysaccharide Supplementation on Training Adaptations in Resistance-Trained Males
PURPOSE: Methoxyisoflavone (M), 20-hydroxyecdysone (E), and sulfo-polysaccharide (CSP3) have been marketed to athletes as dietary supplements that can increase strength and muscle mass during resistancetraining. However, little is known about their potential ergogenic value. The purpose of this study was to determine whether these supplements affect training adaptations and/or markers of muscle anabolism/catabolism in resistance-trained athletes. METHODS: Forty-five resistance-trained males (20.5Âą3 yrs; 179Âą7 cm, 84Âą16 kg, 17.3Âą9 % body fat) were matched according to FFM and randomly assigned to ingest in a double blind manner supplements containing either a placebo (P); 800 mg/day of M; 200 mg of E; or, 1,000 mg/day of CSP3 for 8-weeks during training. At 0, 4, and 8-weeks, subjects donated fasting blood samples and completed comprehensive muscular strength, muscular endurance, anaerobic capacity, and body composition analysis. Data were analyzed by repeated measures ANOVA. RESULTS: No significant differences (p>0.05) were observed in training adaptations among groups in the variables FFM, percent body fat, bench press 1RM, leg press 1RM or sprint peak power. Anabolic/catabolic analysis revealed no significant differences among groups in active testosterone (AT), free testosterone (FT), cortisol, the AT to cortisol ratio, urea nitrogen, creatinine, the blood urea nitrogen to creatinine ratio. In addition, no significant differences were seen from pr
Following wrong suggestions: self-blame in human and computer scenarios
This paper investigates the specific experience of following a suggestion by
an intelligent machine that has a wrong outcome and the emotions people feel.
By adopting a typical task employed in studies on decision-making, we presented
participants with two scenarios in which they follow a suggestion and have a
wrong outcome by either an expert human being or an intelligent machine. We
found a significant decrease in the perceived responsibility on the wrong
choice when the machine offers the suggestion. At present, few studies have
investigated the negative emotions that could arise from a bad outcome after
following the suggestion given by an intelligent system, and how to cope with
the potential distrust that could affect the long-term use of the system and
the cooperation. This preliminary research has implications in the study of
cooperation and decision making with intelligent machines. Further research may
address how to offer the suggestion in order to better cope with user's
self-blame.Comment: To be published in the Proceedings of IFIP Conference on
Human-Computer Interaction (INTERACT)201
Current strategies for monitoring men with localised prostate cancer lack a strong evidence base: observational longitudinal study
Consensus-based guidelines for Video EEG monitoring in the pre-surgical evaluation of children with epilepsy in the UK
PURPOSE:
Paediatric Epilepsy surgery in the UK has recently been centralised in order to improve expertise and quality of service available to children. Video EEG monitoring or telemetry is a highly specialised and a crucial component of the pre-surgical evaluation. Although many Epilepsy Monitoring Units work to certain standards, there is no national or international guideline for paediatric video telemetry.
METHODS:
Due to lack of evidence we used a modified Delphi process utilizing the clinical and academic expertise of the clinical neurophysiology sub-specialty group of Childrenâs Epilepsy Surgical Service (CESS) centres in England and Wales. This process consisted of the following stages I: Identification of the consensus working group, II: Identification of key areas for guidelines, III: Consensus practice points and IV: Final review. Statements that gained consensus (median score of either 4 or 5 using a five-point Likerttype scale) were included in the guideline.
RESULTS:
Two rounds of feedback and amendments were undertaken. The consensus guidelines includes the following topics: referral pathways, neurophysiological equipment standards, standards of recording techniques, with specific emphasis on safety of video EEG monitoring both with and without drug withdrawal, a protocol for testing patientâs behaviours, data storage and guidelines for writing factual reports and conclusions. All statements developed received a median score of 5 and were adopted by the group.
CONCLUSIONS:
Using a modified Delphi process we were able to develop universally-accepted video EEG guidelines for the UK CESS. Although these recommendations have been specifically developed for the pre-surgical evaluation of children with epilepsy, it is assumed that most components are transferable to any paediatric video EEG monitoring setting
Mandibular Actinomyces osteomyelitis complicating florid cemento-osseous dysplasia: case report
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