649 research outputs found
Dried brewers’ grain as a replacement for soybean meal on nutrient digestibility and rumen parameters of cattle
The objective of this study was to determine the effect of replacing soybean meal with dried brewers’ grains (DBG) in intake and digestibility of the nutrients and the ruminal parameters of cattle. Four ruminal cannulated Jersey oxen with initial body weight of 662.7 ± 85.5 kg were distributed in a 4x4 Latin square design. The treatments were levels of 0%, 33%, 66% and 100% DBG replacing soybean meal in the diet. Dry matter (DM) and crude protein (CP) intake were not influenced by the treatments. There were linear increases in ether extract (EE), neutral detergent fibre (NDF) and acid detergent fibre (ADF) intakes because of higher levels of these nutrients in diets with DBG. Non-fibre carbohydrate (NFC) and total digestible nutrient (TDN) intake showed a decreasing linear effect. Dry matter and NFC digestibility decreased linearly with rising DBG levels, while EE, CP, NDF and ADF digestibilities were not affected. Ruminal pH was not influenced by DBG levels in the diet. There was a quadratic effect in ammonia nitrogen (NH3-N) concentration in the rumen, with the maximum occurring at a level of 36.7% DGB. The replacement of soybean meal with DBG in cattle diets did not alter DM intake and ruminal pH, but reduced TDN intake.Keywords: Ammonia nitrogen, by-product, digestibility, intake, p
How can the Odderon be detected at RHIC and LHC
The Odderon remains an elusive object, 33 years after its invention. The
Odderon is now a fundamental object in QCD and CGC and it has to be found
experimentally if QCD and CGC are right. In the present paper, we show how to
find it at RHIC and LHC. The most spectacular signature of the Odderon is the
predicted difference between the differential cross-sections for proton-proton
and antiproton-proton at high s and moderate t. The experiment can be done by
using the STAR detector at RHIC and by combining these future data with the
already present UA4/2 data. The Odderon could also be found by ATLAS
exeperiment at LHC by performing a high-precision measurement of the real part
of the hadron elastic scattering amplitude at small t.Comment: 14 pages, 16 figures, two typographical errors corrected and
acknowledgments adde
Importance of a deficiency in S-adenosyl-L-methionine synthesis in the pathogenesis of liver injury
One of the features of liver cirrhosis is an abnormal metabolism of methionine--a characteristic that was described more than a half a century ago. Thus, after an oral load of methionine, the rate of clearance of this amino acid from the blood is markedly impaired in cirrhotic patients compared with that in control subjects. Almost 15 y ago we observed that the failure to metabolize methionine in cirrhosis was due to an abnormally low activity of the enzyme methionine adenosyltransferase (EC 2.5.1.6). This enzyme converts methionine, in the presence of ATP, to S-adenosyl-L-methionine (SAMe), the main biological methyl donor. Since then, it has been suspected that a deficiency in hepatic SAMe may contribute to the pathogenesis of the liver in cirrhosis. The studies reviewed here are consistent with this hypothesis
Total photoproduction cross-section at very high energy
In this paper we apply to photoproduction total cross-section a model we have
proposed for purely hadronic processes and which is based on QCD mini-jets and
soft gluon re-summation. We compare the predictions of our model with the HERA
data as well as with other models. For cosmic rays, our model predicts
substantially higher cross-sections at TeV energies than models based on
factorization but lower than models based on mini-jets alone, without soft
gluons. We discuss the origin of this difference.Comment: 13 pages, 9 figures. Accepted for publication in EPJC. Changes
concern added references, clarifications of the Soft Gluon Resummation method
used in the paper, and other changes requested by the Journal referee which
do not change the results of the original versio
Elastic and quasi-elastic and scattering in the Dipole Model
We have in earlier papers presented an extension of Mueller's dipole cascade
model, which includes sub-leading effects from energy conservation and running
coupling as well as colour suppressed saturation effects from pomeron loops via
a ``dipole swing''. The model was applied to describe the total and diffractive
cross sections in and collisions, and also the elastic cross
section in scattering.
In this paper we extend the model to describe the corresponding quasi-elastic
cross sections in , namely the exclusive production of vector mesons
and deeply virtual compton scattering. Also for these reactions we find a good
agrement with measured cross sections. In addition we obtain a reasonable
description of the -dependence of the elastic and quasi-elastic
cross sections
S-Adenosylmethionine revisited: its essential role in the regulation of liver function
Dietary methionine is mainly metabolized in the liver where it is converted into S-adenosylmethionine (AdoMet), the main biologic methyl donor. This reaction is catalyzed by methionine adenosyltransferase I/III (MAT I/III), the product of MAT1A gene, which is exclusively expressed in this organ. It was first observed that serum methionine levels were elevated in experimental models of liver damage and in liver cirrhosis in human beings. Results of further studies showed that this pathological alteration was due to reduced MAT1A gene expression and MAT I/III enzyme inactivation associated with liver injury. Synthesis of AdoMet is essential to all cells in the organism, but it is in the liver where most of the methylation reactions take place. The central role played by AdoMet in cellular function, together with the observation that AdoMet administration reduces liver damage caused by different agents and improves survival of alcohol-dependent patients with cirrhosis, led us to propose that alterations in methionine metabolism could play a role in the onset of liver disease and not just be a consequence of it. In the present work, we review the recent findings that support this hypothesis and highlight the mechanisms behind the hepatoprotective role of AdoMet
Redox regulation of methylthioadenosine phosphorylase in liver cells: molecular mechanism and functional implications
MTAP (5'-methylthioadenosine phosphorylase) catalyses the reversible phosphorolytic cleavage of methylthioadenosine leading to the production of methylthioribose-1-phosphate and adenine. Deficient MTAP activity has been correlated with human diseases including cirrhosis and hepatocellular carcinoma. In the present study we have investigated the regulation of MTAP by ROS (reactive oxygen species). The results of the present study support the inactivation of MTAP in the liver of bacterial LPS (lipopolysaccharide)-challenged mice as well as in HepG2 cells after exposure to t-butyl hydroperoxide. Reversible inactivation of purified MTAP by hydrogen peroxide results from a reduction of V(max) and involves the specific oxidation of Cys(136) and Cys(223) thiols to sulfenic acid that may be further stabilized to sulfenyl amide intermediates. Additionally, we found that Cys(145) and Cys(211) were disulfide bonded upon hydrogen peroxide exposure. However, this modification is not relevant to the mediation of the loss of MTAP activity as assessed by site-directed mutagenesis. Regulation of MTAP by ROS might participate in the redox regulation of the methionine catabolic pathway in the liver. Reduced MTA (5'-deoxy-5'-methylthioadenosine)-degrading activity may compensate for the deficient production of the precursor S-adenosylmethionine, allowing maintenance of intracellular MTA levels that may be critical to ensure cellular adaptation to physiopathological conditions such as inflammation
Regulation of mammalian liver methionine adenosyltransferase
S-adenosylmethionine (SAM) is an essential metabolite in all cells. SAM is the most important biological methyl group donor and is a precursor in the synthesis of polyamines. Methionine adenosyltransferase (MAT; EC 2.5.1.6) catalyzes the only known SAM biosynthetic reaction from methionine and ATP. In mammalian tissues, three different forms of MAT (MAT I, MAT III and MAT II) have been identified that are the product of two different genes (MAT1A and MAT2A). Although MAT2A is expressed in all mammalian tissues, the expression of MAT1A is primarily restricted to adult liver. In mammals, up to 85% of all methylation reactions and as much as 48% of methionine metabolism occurs in the liver, which indicates the important role of this organ in the regulation of blood methionine. Recent evidence indicates that not only is SAM the main biological methyl group donor and an intermediate metabolite in methionine catabolism, but it is also an intracellular control switch that regulates essential hepatic functions such as liver regeneration and differentiation as well as the sensitivity of this organ to injury. Therefore, knowledge of factors that regulate the activity of MAT I/III, the specific liver enzyme, is essential to understand how cellular SAM levels are controlled
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