747 research outputs found
Multifrequency Observations of the Virgo Blazars 3C 273 and 3C 279 in CGRO Cycle 8
We report first observational results of multifrequency campaigns on the
prominent Virgo blazars 3C 273 and 3C 279 which were carried out in January and
February 1999. Both blazars are detected from radio to gamma-ray energies. We
present the measured X- to gamma-ray spectra of both sources, and for 3C 279 we
compare the 1999 broad-band (radio to gamma-ray) spectrum to measured previous
ones.Comment: 5 pages including 3 figures, latex2e, to appear in: 'Proc. of the 5th
Compton Symposium', AIP, in pres
Adenosine has two faces: Regionally dichotomous adenosine tone in a model of epilepsy with comorbid sleep disorders
Objective: Adenosine participates in maintaining the excitatory/inhibitory balance in neuronal circuits. Studies indicate that adenosine levels in the cortex and hippocampus increase and exert sleep pressure in sleep-deprived and control animals, whereas in epilepsy reduced adenosine tone promotes hyperexcitability. To date, the role of adenosine in pathological conditions that result in both seizures and sleep disorders is unknown. Here, we determined adenosine tone in sleep and seizure regulating brain regions of Kv1.1 knockout (KO) mice, a model of temporal epilepsy with comorbid sleep disorders.
Methods: 1) Reverse phase-high performance liquid chromatography (RP-HPLC) was performed on brain tissue to determine levels of adenosine and adenine nucleotides. 2) Multi-electrode array extracellular electrophysiology was used to determine adenosine tone in the hippocampal CA1 region and the lateral hypothalamus (LH).
Results: RP-HPLC indicated a non-significant decrease in adenosine (~50%, p = 0.23) in whole brain homogenates of KO mice. Regional examination of relative levels of adenine nucleotides indicated decreased ATP and increased AMP in the cortex and hippocampus and increased adenosine in cortical tissue. Using electrophysiological and pharmacological techniques, estimated adenosine levels were ~35% lower in the KO hippocampal CA1 region, and 1–2 fold higher in the KO LH. Moreover, the increased adenosine in KO LH contributed to lower spontaneous firing rates of putative wake-promoting orexin/hypocretin neurons.
Interpretation: This is the first study to demonstrate a direct correlation of regionally distinct dichotomous adenosine levels in a single model with both epilepsy and comorbid sleep disorders. The weaker inhibitory tone in the dorsal hippocampus is consistent with lower seizure threshold, whereas increased adenosine in the LH is consistent with chronic partial sleep deprivation. This work furthers our understanding of how adenosine may contribute to pathological conditions that underlie sleep disorders within the epileptic brain
Coordinated regulation of transcription by CcpA and the \u3ci\u3eStaphylococcus aureus\u3c/i\u3e twocomponent system HptRS
The success of Staphylococcus aureus as a pathogen is due in part to its ability to adapt to changing environmental conditions using signal transduction pathways, such as metaboliteresponsive regulators and two-component systems. S. aureus has a two-component system encoded by the gene pair sav0224 (hptS) and sav0223 (hptR) that regulate the hexose phosphate transport (uhpT) system in response to extracellular glucose-6-phosphate. Glycolytic intermediates such as glucose-6-phosphate are important carbon sources that also modulate the activity of the global metabolite-responsive transcriptional regulator CcpA. Because uhpT has a putative CcpA binding site in its promoter and it is regulated by HptR, it was hypothesized the regulons of CcpA and HptR might intersect. To determine if the regulatory domains of CcpA and HptRS overlap, ccpA was deleted in strains SA564 and SA564- ΔhptRS and growth, metabolic, proteomic, and transcriptional differences were assessed. As expected, CcpA represses hptS and hptR in a glucose dependent manner; however, upon CcpA derepression, the HptRS system functions as a transcriptional activator of metabolic genes within the CcpA regulon. Importantly, inactivation of ccpA and hptRS altered sensitivity to fosfomycin and ampicillin in the absence of exogenous glucose-6-phosphate, indicating that both CcpA and HptRS modulate antibiotic susceptibility
Comparison of antibacterial activity of phytochemicals against common foodborne pathogens and potential for selection of resistance
Antimicrobial resistance is now commonly observed in bacterial isolates from multiple settings, compromising the efficacy of current antimicrobial agents. Therefore, there is an urgent requirement for efficacious novel antimicrobials to be used as therapeutics, prophylactically or as preservatives. One promising source of novel antimicrobial chemicals is phytochemicals, which are secondary metabolites produced by plants for numerous purposes, including antimicrobial defence. In this report, we compare the bioactivity of a range of phytochemical compounds, testing their ability to directly inhibit growth or to potentiate other antimicrobials against Salmonella enterica Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus. We found that nine compounds displayed consistent bioactivity either as direct antimicrobials or as potentiators. Thymol at 0.5 mg/mL showed the greatest antimicrobial effect and significantly reduced the growth of all species, reducing viable cell populations by 66.8%, 43.2%, 29.5%, and 70.2% against S. enterica Typhimurium, S. aureus, P. aeruginosa, and L. monocytogenes, respectively. Selection of mutants with decreased susceptibility to thymol was possible for three of the pathogens, at a calculated rate of 3.77 × 10−8, and characterisation of S. enterica Typhimurium mutants showed a low-level MDR phenotype due to over-expression of the major efflux system AcrAB-TolC. These data show that phytochemicals can have strong antimicrobial activity, but emergence of resistance should be evaluated in any further development
Accurate non-invasive diagnosis and staging of non-alcoholic fatty liver disease using the urinary steroid metabolome
Background The development of accurate, non-invasive markers to diagnose and stage non-alcoholic fatty liver disease (NAFLD) is critical to reduce the need for an invasive liver biopsy and to identify patients who are at the highest risk of hepatic and cardio-metabolic complications. Disruption of steroid hormone metabolic pathways has been described in patients with NAFLD. Aim(s) To assess the hypothesis that assessment of the urinary steroid metabolome may provide a novel, non-invasive biomarker strategy to stage NAFLD. Methods We analysed the urinary steroid metabolome in 275 subjects (121 with biopsy-proven NAFLD, 48 with alcohol-related cirrhosis and 106 controls), using gas chromatography-mass spectrometry (GC-MS) coupled with machine learning-based Generalised Matrix Learning Vector Quantisation (GMLVQ) analysis. Results Generalised Matrix Learning Vector Quantisation analysis achieved excellent separation of early (F0-F2) from advanced (F3-F4) fibrosis (AUC receiver operating characteristics [ROC]: 0.92 [0.91-0.94]). Furthermore, there was near perfect separation of controls from patients with advanced fibrotic NAFLD (AUC ROC = 0.99 [0.98-0.99]) and from those with NAFLD cirrhosis (AUC ROC = 1.0 [1.0-1.0]). This approach was also able to distinguish patients with NAFLD cirrhosis from those with alcohol-related cirrhosis (AUC ROC = 0.83 [0.81-0.85]). Conclusions Unbiased GMLVQ analysis of the urinary steroid metabolome offers excellent potential as a non-invasive biomarker approach to stage NAFLD fibrosis as well as to screen for NAFLD. A highly sensitive and specific urinary biomarker is likely to have clinical utility both in secondary care and in the broader general population within primary care and could significantly decrease the need for liver biopsy
Turnover of passerine birds on islands in the Aegean Sea (Greece)
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73442/1/j.1365-2699.2007.01695.x.pd
Boron isotopic composition of olivine-hosted melt inclusions from Gorgona komatiites, Colombia : new evidence supporting wet komatiite origin
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters 312 (2011): 201–212, doi:10.1016/j.epsl.2011.09.033.A fundamental question in the genesis of komatiites is whether 30 these rocks originate
from partial melting of dry and hot mantle, 400−500°C hotter than typical sources of MORB and
OIB magmas, or if they were produced by hydrous melting of the source at much lower
temperatures, similar or only moderately higher than those known today. Gorgona Island,
Colombia, is a unique place where Phanerozoic komatiites occur and whose origin is directly
connected to the formation of the Caribbean Large Igneous Province. The genesis of Gorgona
komatiites remains controversial, mostly because of the uncertain origin of volatile components
which they appear to contain. These volatiles could equally result from shallow level magma
contamination, melting of a “damp” mantle or fluid-induced partial melting of the source due to
devolatilization of the ancient subducting plate. We have analyzed boron isotopes of olivine40
hosted melt inclusions from the Gorgona komatiites. These inclusions are characterized by
relatively high contents of volatile components and boron (0.2−1.0 wt.% H2O, 0.05−0.08 wt.%
S, 0.02−0.03 wt.% Cl, 0.6−2.0 μg/g B), displaying positive anomalies in the overall depleted,
primitive mantle (PM) normalized trace element and REE spectra ([La/Sm]n = 0.16−0.35;
[H2O/Nb]n = 8−44; [Cl/Nb]n = 27−68; [B/Nb]n = 9-30, assuming 300 μg/g H2O, 8 μg/g Cl and
0.1 μg/g B in PM; Kamenetsky et al., 2010. Composition and temperature of komatiite melts
from Gorgona Island constrained from olivine-hosted melt inclusions. Geology 38, 1003–1006).
The inclusions range in δ11B values from −11.5 to +15.6 ± 2.2‰ (1 SE), forming two distinct
trends in a δ11B vs. B-concentration diagram. Direct assimilation of seawater, seawater-derived
components, altered oceanic crust or marine sediments by ascending komatiite magma cannot
readily account for the volatile contents and B isotope variations. Alternatively, injection of <3%
of a 11B enriched fluid to the mantle source could be a plausible explanation for the δ11B range
that also may explain the H2O, Cl and B excess.Financial support
to AAG during data acquisition and manuscript preparation was provided by Northeast National
Ion Microprobe Facility (Woods Hole Oceanographic Institution, USA) and the Centre de
Recherches Pétrographiqueset Géochimiques (France). This research was also supported by the
Australian Research Council (Research Fellowship and Discovery grants to VSK). We
acknowledge partial support of the Alexander von Humboldt Foundation, Germany (F.W. Bessel
Award to VSK and Wolfgang Paul Award to A.V. Sobolev who provided access to the electron
microprobe at the Max Planck Institute, Mainz, Germany
Sustainable Urban Systems: Co-design and Framing for Transformation
Rapid urbanisation generates risks and opportunities for sustainable development. Urban policy and decision makers are challenged by the complexity of cities as social–ecological–technical systems. Consequently there is an increasing need for collaborative knowledge development that supports a whole-of-system view, and transformational change at multiple scales. Such holistic urban approaches are rare in practice. A co-design process involving researchers, practitioners and other stakeholders, has progressed such an approach in the Australian context, aiming to also contribute to international knowledge development and sharing. This process has generated three outputs: (1) a shared framework to support more systematic knowledge development and use, (2) identification of barriers that create a gap between stated urban goals and actual practice, and (3) identification of strategic focal areas to address this gap. Developing integrated strategies at broader urban scales is seen as the most pressing need. The knowledge framework adopts a systems perspective that incorporates the many urban trade-offs and synergies revealed by a systems view. Broader implications are drawn for policy and decision makers, for researchers and for a shared forward agenda
An improved predictive recognition model for Cys2-His2 zinc finger proteins
Cys2-His2 zinc finger proteins (ZFPs) are the largest family of transcription factors in higher metazoans. They also represent the most diverse family with regards to the composition of their recognition sequences. Although there are a number of ZFPs with characterized DNA-binding preferences, the specificity of the vast majority of ZFPs is unknown and cannot be directly inferred by homology due to the diversity of recognition residues present within individual fingers. Given the large number of unique zinc fingers and assemblies present across eukaryotes, a comprehensive predictive recognition model that could accurately estimate the DNA-binding specificity of any ZFP based on its amino acid sequence would have great utility. Toward this goal, we have used the DNA-binding specificities of 678 two-finger modules from both natural and artificial sources to construct a random forest-based predictive model for ZFP recognition. We find that our recognition model outperforms previously described determinant-based recognition models for ZFPs, and can successfully estimate the specificity of naturally occurring ZFPs with previously defined specificities
Genome-wide meta-analysis of muscle weakness identifies 15 susceptibility loci in older men and women.
Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10-17), arthritis (GDF5 p = 4 × 10-13), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing
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