544 research outputs found
Online matching on a line
We prove a lower bound ρ ≥ 9.001 for the competitive ratio of the so-called online matching problem on a line. As a consequence, the online matching problem is revealed to be strictly more difficult than the "cow problem". \u
The two novel MHC class II transactivators RFX5 and CIITA both control expression of HLA-DM genes
MHC-encoded HLA-DMA and-DMB molecules are atypical MHC chains that play an essential role in antigen presentation by MHC class II molecules. They resemble both MHC class I and II molecules but are not expressed at the cell surface. From the study of MHC class II regulatory mutants, it was found recently that two novel transactivators, CIITA and RFX5, are essential for the control of MHC class II gene expression. We report here that CIITA and RFX5, although operating at different levels of transcriptional control, are also both essential regulators of HLA-DMA and-DMB genes. This is true for both the constitutive and the inducible mode of DM gene expression. Indeed, both CIITA and RFX5 cDNA can correct the HLA-DMA and-DMB gene expression defect in the respective regulatory mutants. The involvement of these two transcription factors accounts for the coordinate expression of MHC class II and HLA-DM, two sets of molecules that perform quite different functions in the overall process of antigen presentatio
Comparative study of the catalytic growth of patterned carbon nanotube films
Three different catalysts (Fe, Ni, Co nitrates dissolved in ethanol) were
patterned on a SiO2/Si substrate and multi-wall carbon nanotubes were grown by
catalytic decomposition of acetylene. We compare the growth of the carbon
nanostructures in the temperature range between 580C and 1000C. With our
experimental set-up the catalyst solutions of cobalt and nickel were found to
be less efficient than the one of iron. An optimal production of multi-wall
nanotubes was observed at temperatures between 650C and 720C with the iron
solution as catalyst. We found a tendency towards thicker structures with
higher temperatures. Finally, we suggest a mechanism for the growth of these
carbon structures.Comment: 5 pages, 5 figure
The asparagine-transamidosome from Helicobacter pylori: a dual-kinetic mode in non-discriminating aspartyl-tRNA synthetase safeguards the genetic code
Helicobacter pylori catalyzes Asn-tRNAAsn formation by use of the indirect pathway that involves charging of Asp onto tRNAAsn by a non-discriminating aspartyl-tRNA synthetase (ND-AspRS), followed by conversion of the mischarged Asp into Asn by the GatCAB amidotransferase. We show that the partners of asparaginylation assemble into a dynamic Asn-transamidosome, which uses a different strategy than the Gln-transamidosome to prevent the release of the mischarged aminoacyl-tRNA intermediate. The complex is described by gel-filtration, dynamic light scattering and kinetic measurements. Two strategies for asparaginylation are shown: (i) tRNAAsn binds GatCAB first, allowing aminoacylation and immediate transamidation once ND-AspRS joins the complex; (ii) tRNAAsn is bound by ND-AspRS which releases the Asp-tRNAAsn product much slower than the cognate Asp-tRNAAsp; this kinetic peculiarity allows GatCAB to bind and transamidate Asp-tRNAAsn before its release by the ND-AspRS. These results are discussed in the context of the interrelation between the Asn and Gln-transamidosomes which use the same GatCAB in H. pylori, and shed light on a kinetic mechanism that ensures faithful codon reassignment for Asn
The Influence of a KDT501, a Novel Isohumulone, on Adipocyte Function in Humans
Objective: In a phase II clinical trial in nine obese, insulin-resistant humans, we observed that treatment with KDT501, a novel isohumulone drug, increased total and high-molecular weight (HMW) adiponectin in plasma. The objective was to determine whether KDT501 increased adiponectin secretion from subcutaneous white adipose tissue (SC WAT) and the underlying mechanism(s).
Methods: Nine obese participants with either prediabetes or with normal glucose tolerance plus three features of metabolic syndrome were part of the study. SC WAT biopsies were performed before and after 28 days of KDT501 treatment in a clinical research setting. In addition, a cold stimulus was used to induce thermogenic gene expression. Adiponectin secretion was measured, and gene expression of 130 genes involved in adipose tissue function was determined. The effect of KDT501 on adipocyte mitochondrial function was analyzed in vitro.
Results: SC WAT explants secreted more total and HMW adiponectin after KDT501 treatment (P \u3c 0.05). After KDT501 treatment, a number of genes involved in thermogenesis and lipolysis were induced by cold (P \u3c 0.05). KDT501 also potentiated β-adrenergic signaling (P \u3c 0.001) and enhanced mitochondrial function in adipocytes (P \u3c 0.001).
Conclusion: KDT501 induced adiponectin secretion posttranscriptionally and increased gene expression of thermogenic and lipolytic genes in response to cold stimulation. These beneficial effects on SC WAT may be explained by the ability of KDT501 to potentiate β-adrenergic signaling and enhance mitochondrial function in adipocytes.
Clinical Trial Registration: https://www.ClinicalTrials.gov, ID number: NCT02444910
Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System
The exclusive reaction , at 18 GeV has been studied with a partial wave analysis on a sample
of 23~492 events from BNL experiment E852. A mass-dependent fit
is consistent with a resonant hypothesis for the wave, thus providing
evidence for a neutral exotic meson with , a mass of MeV, and a width of MeV. New
interpretations of the meson exotics in neutral system observed in
E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase
variations. p4, rewording paragrath "The second method ..." . p4, at the
bottom of paragrath "The third method ..." added consistent with the results
of methods 1 and 2
Exotic Meson Production in the System observed in the Reaction at 18 GeV/c
This letter reports results from the partial wave analysis of the
final state in collisions at 18GeV/c.
Strong evidence is observed for production of two mesons with exotic quantum
numbers of spin, parity and charge conjugation, in the decay
channel . The mass MeV/c^2 and
width MeV/c^2 of the first state are consistent
with the parameters of the previously observed . The second
resonance with mass MeV/c^2 and width MeV/c^2 agrees very well with predictions from theoretical
models. In addition, the presence of is confirmed with mass MeV/c^2 and width MeV/c^2
and a new state, , is observed with mass
MeV/c^2 and width MeV/c^2. The decay properties of
these last two states are consistent with flux tube model predictions for
hybrid mesons with non-exotic quantum numbers
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