Hepatic glycogen participates in the regulation of hypothalamic pAkt/Akt ratio in high-sugar/high-fat diet-induced obesity

The hypothalamus is a major integrating centre that controls energy homeostasis and plays a major role in hepatic glycogen (HGlyc) turnover. Not only do hypothalamic and hepatic Akt levels influence glucose homeostasis and glycogen synthesis, but exposure to high-sugar/high-fat diets (HSHF) can also lead to hypothalamic inflammation and HGlyc accumulation. HSHF withdrawal overall restores energy and glucose homeostasis, but the actual relationship between hypothalamic inflammation and HGlyc after short-term HSHF withdrawal has not yet been fully elucidated. Here we investigated the short-term effects of HSHF withdrawal preceded by a 30-day HSHF intake on the liver-hypothalamus crosstalk and glucose homeostasis. Sixty-day old male Wistar rats were fed for 30 days a control chow (n = 10) (Ct), or an HSHF diet (n = 20). On the 30th day of dietary intervention, a random HSHF subset (n = 10) had their diets switched to control chow for 48 h (Hw) whilst the remaining HSHF rats remained in the HSHF diet (n = 10) (Hd). All rats were anaesthetized and euthanized at the end of the protocol. We quantified HGlyc, Akt phosphorylation, inflammation and glucose homeostasis biomarkers. We also assessed the effect of propensity to obesity on those biomarkers, as detailed previously. Hd rats showed impaired glucose homeostasis, higher HGlyc and hypothalamic inflammation, and lower pAkt/Akt. Increased HGlyc was significantly associated with HSHF intake on pAkt/Akt lowered levels. We also found that HGlyc breakdown may have prevented a further pAkt/Akt drop after HSHF withdrawal. Propensity to obesity showed no apparent effect on hypothalamic inflammation or glucose homeostasis. Our findings suggest a comprehensive role of HGlyc as a structural and functional modulator of energy metabolism, and such roles may come into play relatively rapidly

The Gaia-ESO Survey: The most metal-poor stars in the Galactic bulge

We present the first results of the EMBLA survey (Extremely Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor stars in the Milky Way bulge, where the oldest stars should now preferentially reside. EMBLA utilizes SkyMapper photometry to pre-select metal-poor candidates, which are subsequently confirmed using AAOmega spectroscopy. We describe the discovery and analysis of four bulge giants with -2.72 = [Fe/H] = -2.48, the lowest metallicity bulge stars studied with high-resolution spectroscopy to date. Using FLAMES/UVES spectra through the Gaia-ESO Survey we have derived abundances of twelve elements. Given the uncertainties, we find a chemical similarity between these bulge stars and halo stars of the same metallicity, although the abundance scatter may be larger, with some of the stars showing unusual [a/Fe] ratios

Recent progress in low-temperature silicon detectors

The CERN RD39 Collaboration studies the possibility to extend the detector lifetime in a hostile radiation environment by operating them at low temperatures. The outstanding illustration is the Lazarus effect, which showed a broad operational temperature range around 130 K for neutron irradiated silicon detectors

The effect of charge collection recovery in silicon p-n junction detectors irradiated by different particles

The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called "Lazarus effect", was studied in Si detectors irradiated by fast reactor neutrons, by protons of medium and high energy, by pions and by gamma-rays. The experimental results show that the Lazarus effect is observed: (a) after all types of irradiation; (b) before and after space charge sign inversion; (c) only in detectors that are biased at voltages resulting in partial depletion at room temperature. The experimental temperature dependence of the CCE for proton- irradiated detectors shows non-monotonic behaviour with a maximum at a temperature defined as the CCE recovery temperature. The model of the effect for proton-irradiated detectors agrees well with that developed earlier for detectors irradiated by neutrons. The same midgap acceptor-type and donor-type levels are responsible for the Lazarus effect in detectors irradiated by neutrons and by protons. A new, abnormal "zigzag"-shaped temperature dependence of the CCE was observed for detectors irradiated by all particles (neutrons, protons and pions) and by an ultra-high dose of gamma-rays, when operating at low bias voltages. This effect is explained in the framework of the double-peak electric field distribution model for heavily irradiated detectors. The redistribution of the space charge region depth between the depleted regions adjacent to p(+) and n(+) contacts is responsible for the "zigzag"-shaped curves. It is shown that the CCE recovery temperature increases with reverse bias in all detectors, regardless of the type of radiation