8,909 research outputs found
Ghrelin, motilin in health and disease
Ghrelin is a 28 amino-acid peptide produced predominantly by the stomach. Two main
isoforms of ghrelin are currently known (octanoyl- and desoctanoyl ghrelin). It
functions as a circulating orexigenic hormone In addition, it has an effect on the
nervous, cardiovascular and immune system. Current data suggest that ghrelin may have
beneficial anti-inflammatory effects. Chapter 3 in this thesis primarily examines the
relationship between ghrelin and inflammation in Crohn’s disease (CD). Modulation of
inflammation with infliximab, a powerful anti-TNFα antibody therapy, can increase
total ghrelin concentration by 25%. In addition, a normal physiological post-prandial
decrease in ghrelin following a meal is restored when infused with infliximab,
suggesting a dysregulation of ghrelin in CD patients with active inflammation. At
cellular level, there is evidence that ghrelin may have an immunosuppressive effect on
activated T-lymphocytes. Chapter 4 of this thesis examines the effect of ghrelin, a
manufactured agonist and des-octanoyl ghrelin on NFκB activation on a human Blymphocyte
cell line. This study demonstrated that exposure to octanoyl ghrelin confers
an initial increase of NFκB activation in inactivated cells of up to 50% which suggests a
pro-inflammatory effect. However, NFκB activation appears to decrease at much higher
concentrations of octanoyl ghrelin, which may indicate toxicity at supra-physiological
levels. Ghrelin is also involved in the regulation of gastric motility and has structural
similarities to motilin. Symptoms of delayed gastric emptying can occur long after
cancer chemotherapy has ended. Chapter 5 of this thesis compares the contractility and
pro-motility neurotransmitter expression in chemotherapy and non-chemotherapy
exposed stomach tissues obtained from patients undergoing surgery for oesophagogastric
cancers. Chemotherapy exposed tissues have reduced contractility to carbachol
and apparent destruction of the cholinergic activity. The tendency for ghrelin receptors
to increase suggests an attempt to upregulate compensating systems. In conclusion,
ghrelin can be altered by inflammation and may have beneficial effects on gastric
motility
In silico identification of the key components and steps in IFN-γ induced JAK-STAT signaling pathway
Systems biology efforts are increasingly adopting quantitative, mechanistic modeling to study cellular signal transduction pathways and other networks. However, it is uncertain whether the particular set of kinetic parameter values of the model closely approximates the corresponding biological system. We propose that the parameters be assigned statistical distributions that reflect the degree of uncertainty for a comprehensive simulation analysis. From this analysis, we globally identify the key components and steps in signal transduction networks at a systems level. We investigated a recent mathematical model of interferon gamma induced Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling pathway by applying multi-parametric sensitivity analysis that is based on simultaneous variation of the parameter values. We find that suppressor of cytokine signaling-1, nuclear phosphatases, cytoplasmic STAT1, and the corresponding reaction steps are sensitive perturbation points of this pathway
Type II superconductivity in SrPd2Ge2
Previous investigations have shown that SrPd2Ge2, a compound isostructural
with "122" iron pnictides but iron- and pnictogen-free, is a conventional
superconductor with a single s-wave energy gap and a strongly three-dimensional
electronic structure. In this work we reveal the Abrikosov vortex lattice
formed in SrPd2Ge2 when exposed to magnetic field by means of scanning
tunneling microscopy and spectroscopy. Moreover, by examining the differential
conductance spectra across a vortex and estimating the upper and lower critical
magnetic fields by tunneling spectroscopy and local magnetization measurements,
we show that SrPd2Ge2 is a strong type II superconductor with \kappa >>
sqrt(2). Also, we compare the differential conductance spectra in various
magnetic fields to the pair breaking model of Maki - de Gennes for dirty limit
type II superconductor in the gapless region. This way we demonstrate that the
type II superconductivity is induced by the sample being in the dirty limit,
while in the clean limit it would be a type I superconductor with \kappa\ <<
sqrt(2), in concordance with our previous study (T. Kim et al., Phys. Rev. B
85, (2012)).Comment: 9 pages, 4 figure
Domestic Value Added and Employment Generated by Chinese Exports: A Quantitative Estimation
We develop an input-output methodology to estimate how Chinese exports affect the country’s total domestic value added (DVA) and employment for 1995 and 2002. Total DVA generated by exports is obtained by subtracting all direct and indirect imported intermediate goods from the gross value of exports, and total employment is obtained by adding all direct and indirect employment generated by exports. To implement these estimations, we use hitherto unpublished Chinese government data to construct several completely new datasets, including an input-output table with separate input-output and employment-output coefficients for processing and non-processing exports. In 2002 (1995), for every US466 (US$545) and 0.242 (0.375) person-year, respectively.Input-output tables, Chinese exports, employment, domestic value added
DeformSyncNet: Deformation Transfer via Synchronized Shape Deformation Spaces
Shape deformation is an important component in any geometry processing toolbox. The goal is to enable intuitive deformations of single or multiple shapes or to transfer example deformations to new shapes while preserving the plausibility of the deformed shape(s). Existing approaches assume access to point-level or part-level correspondence or establish them in a preprocessing phase, thus limiting the scope and generality of such approaches. We propose DeformSyncNet, a new approach that allows consistent and synchronized shape deformations without requiring explicit correspondence information. Technically, we achieve this by encoding deformations into a class-specific idealized latent space while decoding them into an individual, model-specific linear deformation action space, operating directly in 3D. The underlying encoding and decoding are performed by specialized (jointly trained) neural networks. By design, the inductive bias of our networks results in a deformation space with several desirable properties, such as path invariance across different deformation pathways, which are then also approximately preserved in real space. We qualitatively and quantitatively evaluate our framework against multiple alternative approaches and demonstrate improved performance
Maximally Supersymmetric Yang-Mills in five dimensions in light-cone superspace
We formulate maximally supersymmetric Yang-Mills theory in five dimensions in
light-cone superspace. The light-cone Hamiltonian is of the quadratic form and
the theory can be understood as an oxidation of the N=4 Super Yang-Mills Theory
in four dimensions. We specifically study three-point counterterms and show how
these counterterms vanish on-shell. This study is a preliminary to set up the
technique in order to study possible four-point counterterms.Comment: 25 pages, typos corrected, references adde
Simultaneous effects of water and nitrogen stress on the vegetative and yield parameters of choy sum (Brassica chinensis var. parachinensis)
Hypothetically, leafy vegetables need water and nitrogen (N) simultaneously in their applications for good growth. Therefore, this study was conducted to determine the effects of four watering frequencies (watering once a day, once a week and once in every two weeks and no watering) and five levels of nitrogen (0, 34, 68, 136 and 272 kg N ha-1) on the vegetative and yield parameters of choy sum over a period of four weeks. The choy sum was grown in polyethylene bags under a rain shelter. The experimental design was a split-split plot with four replications. Plant vegetative and yield parameters measured weekly were plant height, leaf number, total leaf area, maximum root length, the various plant part weights and total tissue nitrogen. Water stress detrimentally affected choy sumfs leaf growth more than root growth and the effect of water stress was more than nitrogen stress. Higher nitrogen rates in water-stressed condition increasingly reduced the number of leaves and height of the choy sum. Choy sum grown under once-a-day watering and once-a-week treatments did not experience water stress. The optimal soil water content and nitrogen application rate were 0.4 m3 m-3 and 30 to 40 kg N ha-1, respectively. The rate of 34 kg N ha-1 and once-a-week watering treatment generally gave the highest values for all the measured vegetative and yield parameters. Under lower and point of sufficient nitrogen rates, nitrogen was used for leaf thickness and weight rather than for intercepting light via leaf area expansion
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