164 research outputs found
Atomic Quantum Simulation of Dynamical Gauge Fields coupled to Fermionic Matter: From String Breaking to Evolution after a Quench
Using a Fermi-Bose mixture of ultra-cold atoms in an optical lattice, we
construct a quantum simulator for a U(1) gauge theory coupled to fermionic
matter. The construction is based on quantum links which realize continuous
gauge symmetry with discrete quantum variables. At low energies, quantum link
models with staggered fermions emerge from a Hubbard-type model which can be
quantum simulated. This allows us to investigate string breaking as well as the
real-time evolution after a quench in gauge theories, which are inaccessible to
classical simulation methods.Comment: 14 pages, 5 figures. Main text plus one general supplementary
material and one basic introduction to the topic. Published versio
Nutritional strategies for correcting low glucose values in patients with postbariatric hypoglycaemia: A randomized controlled three-arm crossover trial.
AIM
To evaluate the efficacy of nutritional hypoglycaemia correction strategies in postbariatric hypoglycaemia (PBH) after Roux-en-Y gastric bypass (RYGB).
MATERIALS AND METHODS
In a randomized, controlled, three-arm crossover trial, eight post-RYGB adults (mean [SD] 7.0 [1.4] years since surgery) with PBH ingested a solid mixed meal (584âkcal, 85âg carbohydrates, 21âg fat, 12âg protein) to induce hypoglycaemia on three separate days. Upon reaching plasma glucose of less than 3.0âmmol/L, hypoglycaemia was corrected with 15âg of glucose (G15), 5âg of glucose (G5) or a protein bar (P10, 10âg of protein) in random order. The primary outcome was percentage of time spent in the target plasma glucose range (3.9-5.5âmmol/L) during 40âminutes after correction.
RESULTS
Postcorrection time spent in the target glucose range did not differ significantly between the interventions (Pâ=â.161). However, postcorrection time with glucose less than 3.9âmmol/L was lower after G15 than P10 (Pâ=â.007), whereas time spent with glucose more than 5.5âmmol/L, peak glucose and insulin 15âminutes postcorrection were higher after G15 than G5 and P10 (Pâ<â.001). Glucagon 15âminutes postcorrection was higher after P10 than after G15 and G5 (Pâ=â.002 and Pâ=â.003, respectively). G15 resulted in rebound hypoglycaemia (<â3.0âmmol/L) in three of eight cases (38%), while no rebound hypoglycaemia occurred with G5 and P10.
CONCLUSIONS
Correcting hypoglycaemia with 15âg of glucose should be reconsidered in post-RYGB PBH. A lower dose appears to sufficiently increase glucose levels outside the critical range in most cases, and complementary nutrients (e.g. proteins) may provide glycaemia-stabilizing benefits.
REGISTRATION NUMBER OF CLINICAL TRIAL
NTC05250271 (ClinicalTrials.gov)
Nutritional strategies for correcting low glucose values in patients with postbariatric hypoglycaemia: A randomized controlled threeâarm crossover trial
AimTo evaluate the efficacy of nutritional hypoglycaemia correction strategies in postbariatric hypoglycaemia (PBH) after RouxâenâY gastric bypass (RYGB).Materials and methodsIn a randomized, controlled, threeâarm crossover trial, eight postâRYGB adults (mean [SD] 7.0 [1.4] years since surgery) with PBH ingested a solid mixed meal (584âkcal, 85âg carbohydrates, 21âg fat, 12âg protein) to induce hypoglycaemia on three separate days. Upon reaching plasma glucose of less than 3.0âmmol/L, hypoglycaemia was corrected with 15âg of glucose (G15), 5âg of glucose (G5) or a protein bar (P10, 10âg of protein) in random order. The primary outcome was percentage of time spent in the target plasma glucose range (3.9â5.5âmmol/L) during 40âminutes after correction.ResultsPostcorrection time spent in the target glucose range did not differ significantly between the interventions (Pâ=â.161). However, postcorrection time with glucose less than 3.9âmmol/L was lower after G15 than P10 (Pâ=â.007), whereas time spent with glucose more than 5.5âmmol/L, peak glucose and insulin 15âminutes postcorrection were higher after G15 than G5 and P10 (Pâ<â.001). Glucagon 15âminutes postcorrection was higher after P10 than after G15 and G5 (Pâ=â.002 and Pâ=â.003, respectively). G15 resulted in rebound hypoglycaemia (<â3.0âmmol/L) in three of eight cases (38%), while no rebound hypoglycaemia occurred with G5 and P10.ConclusionsCorrecting hypoglycaemia with 15âg of glucose should be reconsidered in postâRYGB PBH. A lower dose appears to sufficiently increase glucose levels outside the critical range in most cases, and complementary nutrients (e.g. proteins) may provide glycaemiaâstabilizing benefits.Registration number of clinical trialNTC05250271 (ClinicalTrials.gov)
Q-dependence of the inelastic neutron scattering cross section for molecular spin clusters with high molecular symmetry
For powder samples of polynuclear metal complexes the dependence of the
inelastic neutron scattering intensity on the momentum transfer Q is known to
be described by a combination of so called interference terms. They reflect the
interplay between the geometrical structure of the compound and the spatial
properties of the wave functions involved in the transition. In this work, it
is shown that the Q-dependence is strongly interrelated with the molecular
symmetry of molecular nanomagnets, and, if the molecular symmetry is high
enough, is actually completely determined by it. A general formalism connecting
spatial symmetry and interference terms is developed. The arguments are
detailed for cyclic spin clusters, as experimentally realized by e.g. the
octanuclear molecular wheel Cr8, and the star like tetranuclear cluster Fe4.Comment: 8 pages, 1 figures, REVTEX
RNAi Screening Uncovers a Synthetic Sick Interaction between CtIP and the BARD1 Tumor Suppressor
Human CtIP is best known for its role in DNA end resection to initiate DNA double-strand break repair by homologous recombination. Recently, CtIP has also been shown to protect reversed replication forks from nucleolytic degradation upon DNA replication stress. However, still little is known about the DNA damage response (DDR) networks that preserve genome integrity and sustain cell survival in the context of CtIP insufficiency. Here, to reveal such potential buffering relationships, we screened a DDR siRNA library in CtIP-deficient cells to identify candidate genes that induce synthetic sickness/lethality (SSL). Our analyses unveil a negative genetic interaction between CtIP and BARD1, the heterodimeric binding partner of BRCA1. We found that simultaneous disruption of CtIP and BARD1 triggers enhanced apoptosis due to persistent replication stress-induced DNA lesions giving rise to chromosomal abnormalities. Moreover, we observed that the genetic interaction between CtIP and BARD1 occurs independently of the BRCA1-BARD1 complex formation and might be, therefore, therapeutical relevant for the treatment of BRCA-defective tumors.Peer reviewe
Prioritization of zoonotic diseases in Kenya, 2015
INTRODUCTION:Zoonotic diseases have varying public health burden and socio-economic impact across time and geographical settings making their prioritization for prevention and control important at the national level. We conducted systematic prioritization of zoonotic diseases and developed a ranked list of these diseases that would guide allocation of resources to enhance their surveillance, prevention, and control. METHODS:A group of 36 medical, veterinary, and wildlife experts in zoonoses from government, research institutions and universities in Kenya prioritized 36 diseases using a semi-quantitative One Health Zoonotic Disease Prioritization tool developed by Centers for Disease Control and Prevention with slight adaptations. The tool comprises five steps: listing of zoonotic diseases to be prioritized, development of ranking criteria, weighting criteria by pairwise comparison through analytical hierarchical process, scoring each zoonotic disease based on the criteria, and aggregation of scores. RESULTS:In order of importance, the participants identified severity of illness in humans, epidemic/pandemic potential in humans, socio-economic burden, prevalence/incidence and availability of interventions (weighted scores assigned to each criteria were 0.23, 0.22, 0.21, 0.17 and 0.17 respectively), as the criteria to define the relative importance of the diseases. The top five priority diseases in descending order of ranking were anthrax, trypanosomiasis, rabies, brucellosis and Rift Valley fever. CONCLUSION:Although less prominently mentioned, neglected zoonotic diseases ranked highly compared to those with epidemic potential suggesting these endemic diseases cause substantial public health burden. The list of priority zoonotic disease is crucial for the targeted allocation of resources and informing disease prevention and control programs for zoonoses in Kenya
An Evolutionarily Conserved Arginine Is Essential for Tre1 G Protein-Coupled Receptor Function During Germ Cell Migration in Drosophila melanogaster
BACKGROUND: G protein-coupled receptors (GPCRs) play central roles in mediating cellular responses to environmental signals leading to changes in cell physiology and behaviors, including cell migration. Numerous clinical pathologies including metastasis, an invasive form of cell migration, have been linked to abnormal GPCR signaling. While the structures of some GPCRs have been defined, the in vivo roles of conserved amino acid residues and their relationships to receptor function are not fully understood. Trapped in endoderm 1 (Tre1) is an orphan receptor of the rhodopsin class that is necessary for primordial germ cell migration in Drosophila melanogaster embryos. In this study, we employ molecular genetic approaches to identify residues in Tre1 that are critical to its functions in germ cell migration. METHODOLOGY/PRINCIPAL FINDINGS: First, we show that the previously reported scattershot mutation is an allele of tre1. The scattershot allele results in an in-frame deletion of 8 amino acids at the junction of the third transmembrane domain and the second intracellular loop of Tre1 that dramatically impairs the function of this GPCR in germ cell migration. To further refine the molecular basis for this phenotype, we assayed the effects of single amino acid substitutions in transgenic animals and determined that the arginine within the evolutionarily conserved E/N/DRY motif is critical for receptor function in mediating germ cell migration within an intact developing embryo. CONCLUSIONS/SIGNIFICANCE: These structure-function studies of GPCR signaling in native contexts will inform future studies into the basic biology of this large and clinically important family of receptors
A Macroecological Analysis of SERA Derived Forest Heights and Implications for Forest Volume Remote Sensing
Individual trees have been shown to exhibit strong relationships between DBH, height and volume. Often such studies are cited as justification for forest volume or standing biomass estimation through remote sensing. With resolution of common satellite remote sensing systems generally too low to resolve individuals, and a need for larger coverage, these systems rely on descriptive heights, which account for tree collections in forests. For remote sensing and allometric applications, this height is not entirely understood in terms of its location. Here, a forest growth model (SERA) analyzes forest canopy height relationships with forest wood volume. Maximum height, mean, H100, and Lorey's height are examined for variability under plant number density, resource and species. Our findings, shown to be allometrically consistent with empirical measurements for forested communities world-wide, are analyzed for implications to forest remote sensing techniques such as LiDAR and RADAR. Traditional forestry measures of maximum height, and to a lesser extent H100 and Lorey's, exhibit little consistent correlation with forest volume across modeled conditions. The implication is that using forest height to infer volume or biomass from remote sensing requires species and community behavioral information to infer accurate estimates using height alone. SERA predicts mean height to provide the most consistent relationship with volume of the height classifications studied and overall across forest variations. This prediction agrees with empirical data collected from conifer and angiosperm forests with plant densities ranging between 102â106 plants/hectare and heights 6â49 m. Height classifications investigated are potentially linked to radar scattering centers with implications for allometry. These findings may be used to advance forest biomass estimation accuracy through remote sensing. Furthermore, Lorey's height with its specific relationship to remote sensing physics is recommended as a more universal indicator of volume when using remote sensing than achieved using either maximum height or H100
DNA Interactions of Monofunctional Organometallic Ruthenium(II) Antitumor Complexes in Cell-free Media
Modifications of natural DNA in a cell-free medium by antitumor monodentate Ru(II) arene
compounds of the general formula [(eta 6-arene)Ru(en)Cl]+ (arene ) biphenyl, dihydroanthracene,
tetrahydroanthracene, p-cymene, or benzene; en ) ethylenediamine) were studied by atomic absorption,
melting behavior, transcription mapping, circular and linear dichroism, plasmid unwinding, competitive
ethidium displacement, and differential pulse polarography. The results indicate that these complexes
bind preferentially to guanine residues in double-helical DNA. The data are consistent with DNA binding
of the complexes containing biphenyl, dihydroanthracene, or tetrahydroanthracene ligands that involves
combined coordination to G N7 and noncovalent, hydrophobic interactions between the arene ligand and
DNA, which may include arene intercalation and minor groove binding. In contrast, the single hydrocarbon
rings in the p-cymene and benzene ruthenium complexes cannot interact with double-helical DNA by
intercalation. Interestingly, the adducts of the complex containing p-cymene ligand, which has methyl
and isopropyl substituents, distort the conformation and thermally destabilize double-helical DNA distinctly
more than the adducts of the three multiring ruthenium arene compounds. It has been suggested that the
different character of conformational alterations induced in DNA, and the resulting thermal destabilization,
may affect differently further âdownstreamâ effects of damaged DNA and consequently may result in
different biological effects of this new class of metal-based antitumor compounds. The results point to a
unique profile of DNA binding for Ru(II) arene compounds, suggesting that a search for new anticancer
compounds based on this class of complexes may also lead to an altered profile of biological activity in
comparison with that of metal-based antitumor drugs already used in the clinic or currently on clinical
trials
The V471A polymorphism in autophagy-related gene ATG7 modifies age at onset specifically in Italian Huntington disease patients
The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the âREGISTRYâ cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis
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