285 research outputs found
SN 1988Z: Spectro-photometric catalogue and energy estimates
We present a spectro-photometric catalogue of the evolution of supernova
1988Z which combines new and published observations in the radio, optical and
X-ray bands, with the aim of offering a comprehensive view of the evolution of
this object and deriving the total energy radiated since discovery. The major
contribution to the total radiated energy comes at optical to X-ray
frequencies, with a total emission of at least erg (for
Ho=50 km/s) in 8.5 years. A model-dependent extrapolation of this value
indicates that the total radiated energy may be as high as erg. The
high value of the radiated energy supports a scenario in which most of the
kinetic energy of the ejecta is thermalized and radiated in a short interaction
with a dense circumstellar medium of nearly constant density. In this sense,
1988Z is not a supernova but a young and compact supernova remnant.Comment: Accepted to be published in MNRAS (14 pages, 10 figures). Also
available at http://www.inaoep.mx/~itzia
High fat diet-induced non alcoholic fatty liver disease in rats is associated with hyperhomocysteinemia caused by down regulation of the transsulphuration pathway
<p>Abstract</p> <p>Background</p> <p>Hyperhomocysteinemia (HHcy) causes increased oxidative stress and is an independent risk factor for cardiovascular disease. Oxidative stress is now believed to be a major contributory factor in the development of non alcoholic fatty liver disease, the most common liver disorder worldwide. In this study, the changes which occur in homocysteine (Hcy) metabolism in high fat-diet induced non alcoholic fatty liver disease (NAFLD) in rats were investigated.</p> <p>Methods and results</p> <p>After feeding rats a standard low fat diet (control) or a high fat diet (57% metabolisable energy as fat) for 18 weeks, the concentration of homocysteine in the plasma was significantly raised while that of cysteine was lowered in the high fat as compared to the control diet fed animals. The hepatic activities of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CGS), the enzymes responsible for the breakdown of homocysteine to cysteine via the transsulphuration pathway in the liver, were also significantly reduced in the high fat-fed group.</p> <p>Conclusions</p> <p>These results indicate that high fat diet-induced NAFLD in rats is associated with increased plasma Hcy levels caused by down-regulation of hepatic CBS and CGL activity. Thus, HHcy occurs at an early stage in high fat diet-induced NAFLD and is likely to contribute to the increased risk of cardiovascular disease associated with the condition.</p
- …