One Loop Back Reaction On Power Law Inflation

We consider quantum mechanical corrections to a homogeneous, isotropic and spatially flat geometry whose scale factor expands classically as a general power of the co-moving time. The effects of both gravitons and the scalar inflaton are computed at one loop using the manifestly causal formalism of Schwinger with the Feynman rules recently developed by Iliopoulos {\it et al.} We find no significant effect, in marked contrast with the result obtained by Mukhanov {\it et al.} for chaotic inflation based on a quadratic potential. By applying the canonical technique of Mukhanov {\it et al.} to the exponential potentials of power law inflation, we show that the two methods produce the same results, within the approximations employed, for these backgrounds. We therefore conclude that the shape of the inflaton potential can have an enormous impact on the one loop back-reaction.Comment: 28 pages, LaTeX 2 epsilo

Modulation des propriétés ONL de ligands azobenzéniques par coordination de cations métalliques

National audienc

Comparative antilipidemic effect of N-acetylcysteine and sesame oil administration in diet-induced hypercholesterolemic mice

<p>Abstract</p> <p>Background</p> <p>There is an increasing number of novel antilipidemic therapies under consideration. The putative hypolipidemic effect of N-acetylcysteine (NAC) and sesame oil was studied in a mouse model of dietary-induced hypercholesterolemia.</p> <p>Methods</p> <p>Male C57bl/6 mice were assigned to the following groups: (NC) control group, (HC) group receiving test diet supplemented with 2% cholesterol and 0.5% cholic acid for 8 weeks, (HCN) group receiving the test diet with NAC supplementation (230 mg/kg p.o.) and (HCS) group fed the test diet enriched with 10% sesame oil. Total serum cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides were assayed at the beginning and at the end of the experiment. Total peroxides and nitric oxide (NO) levels were measured in the serum at the end of the experiment. Hepatic and aortic lesions were evaluated by haematoxylin-eosin staining.</p> <p>Results</p> <p>Higher serum levels of total and LDL-cholesterol were recorded in all groups fed the high cholesterol diet. The HCN group presented reduced lipid levels compared to HC and HCS groups. No differences were observed between HCS and HC groups. Peroxide content in serum was markedly increased in mice consuming high cholesterol diet. NAC and sesame oil administration led to a significant decrease of serum lipid peroxidation in the levels of control group, whereas only NAC restored NO bioavailability. In terms of liver histology, the lesions observed in HCN group were less severe than those seen in the other high cholesterol groups.</p> <p>Conclusion</p> <p>Co-administration of NAC, but not sesame oil, restored the disturbed lipid profile and improved hepatic steatosis in the studied diet-induced hypercholesterolemic mice. Both agents appear to ameliorate serum antioxidant defense.</p

Phosphoproteomics Screen Reveals Akt Isoform-Specific Signals Linking RNA Processing to Lung Cancer

The three Akt isoforms are functionally distinct. Here we show that their phosphoproteomes also differ, suggesting that their functional differences are due to differences in target specificity. One of the top cellular functions differentially regulated by Akt isoforms is RNA processing. IWS1, an RNA processing regulator, is phosphorylated by Akt3 and Akt1 at Ser720/Thr721. The latter is required for the recruitment of SETD2 to the RNA Pol II complex. SETD2 trimethylates histone H3 at K36 during transcription, creating a docking site for MRG15 and PTB. H3K36me3-bound MRG15 and PTB regulate FGFR-2 splicing, which controls tumor growth and invasiveness downstream of IWS1 phosphorylation. Twenty-one of the twenty-four non-small-cell-lung carcinomas we analyzed express IWS1. More importantly, the stoichiometry of IWS1 phosphorylation in these tumors correlates with the FGFR-2 splicing pattern and with Akt phosphorylation and Akt3 expression. These data identify an Akt isoform-dependent regulatory mechanism for RNA processing and demonstrate its role in lung cancer

High Temperature Phase Transitions in Two-Scalar Theories with Large NN Techniques

We consider a theory of a scalar one-component field $\phi$ coupled to a scalar $N$-component field $\chi$. Using large $N$ techiques we calculate the effective potential in the leading order in $1/N$. We show that this is equivalent to a resummation of an infinite subclass of graphs in perturbation theory, which involve fluctuations of the $\chi$ field only. We study the temperature dependence of the expectation value of the $\phi$ field and the resulting first and second order phase transitions.Comment: 11 pages, LaTex, includes 5 uuencoded postscript figures, OUTP-94-11

Antithrombotic and Antiatherosclerotic Properties of Olive Oil and Olive Pomace Polar Extracts in Rabbits

Olive oil polar lipid (OOPL) extract has been reported to inhibit atherosclerosis development on rabbits. Olive pomace polar lipid (PPL) extract inhibits PAF activity in vitro and the most potent antagonist has been identified as a glycerylether-sn-2-acetyl glycolipid with common structural characteristics with the respective potent antagonist of OOPL. The aim of this study was to investigate the effect of PPL on early atherosclerosis development on rabbits and to compare it with the antiatherosclerotic effect of OOPL. OOPL and PPL inhibition potency, towards both PAF action and PAF binding, was tested in vitro on washed rabbit platelets. Consequently, rabbits were divided into three groups (A, B, and C). All groups were fed atherogenic diet for 22 days. Atherogenic diets in groups B and C were enriched with OOPL and PPL, respectively. At the end of the experimental time, rabbits were euthanized and aortic samples were examined histopathologically. OOPL and PPL inhibited PAF-induced aggregation, as well as specific PAF binding, with PPL being more potent. Free and bound PAF levels and PAF-AH activity were significantly elevated at the end of the experimental time. Plasma total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides levels were also found increased. Groups B and C exhibited significantly increased values of EC50 compared to group A. Histopathological examination revealed that the development of early atherosclerosis lesions in groups B and C were significantly inhibited compared to group A. Significant differences were noted in the early atherosclerosis lesions between groups B and C, thus indicating that PPL exhibit its anti-atherosclerotic activity by blocking PAF receptor. Specific PAF antagonists with similar in vitro and in vivo bioactivity to those that have been previously reported in OOPL exist in PPL