Optimization of skin dose using in-vivo MOSFET dose measurements in bolus/non-bolus fraction ratio: A VMAT and a 3DCRT study.

In-phantom and in-vivo three dimensional conformal radiation therapy (3DCRT) and volumetric modulated arc therapy (VMAT) skin doses, measured with and without bolus in a female anthropomorphic phantom RANDO and in patients, were compared against treatment planning system calculated values. A thorough characterization of the metal oxide semiconductor field effect transistor measurement system was performed prior to the measurements in phantoms and patients. Patients with clinical indication for postoperative external radiotherapy were selected. Skin dose showed higher values with 3DCRT technique compared with VMAT. The increase in skin dose due to the use of bolus was quantified. It was observed that, in the case of VMAT, the bolus effect on the skin dose was considerable when compared with 3DCRT. From the point of view of treatment time, bolus cost, and positioning reproducibility, the use of bolus in these situations can be optimized.

Enhancement of memory consolidation by the histone deacetylase inhibitor sodium butyrate in aged rats.

Here we show that a systemic injection of the histone deacetylase inhibitor (HDACi) sodium butyrate (NaB) immediately after training in a step-down inhibitory avoidance task produced an enhancement of memory consolidation that persisted across consecutive retention tests during 14 days in aged rats, while it did not significantly affect memory in young adults. Control aged and young adult rats showed comparable basal levels of memory retention. Our results suggest that HDACis can display memory-enhancing effects specific for aged animals, even in the absence of age-related memory impairment.

Basolateral amygdala activity is required for enhancement of memory consolidation produced by histone deacetylase inhibition in the hippocampus.

Histone acetylation, a type of chromatin modification that allows increased gene transcription and can be pharmacologically promoted by histone deacetylase (HDAC) inhibitors (HDACis), has been consistently associated with promoting memory formation in the hippocampus. The basolateral nucleus of the amygdala (BLA) is a brain area crucially involved in enabling hormones and drugs to influence memory formation. Here, we show that BLA activity is required for memory enhancement by intrahippocampal administration of an HDACi. Two different HDACis, sodium butyrate (NaB) and trichostatin A (TSA), differentially enhanced the retention of memory for inhibitory avoidance (IA) when administered to the dorsal hippocampus after training. TSA showed a biphasic pattern of response during consolidation, in which infusions given immediately or 3h after training produced memory enhancement, whereas no effect was observed when it was infused 1.5 or 6h posttraining. Muscimol (MUS)-induced unilateral functional inactivation of the BLA prevented the enhancement of memory retention produced by posttraining infusion of TSA into the ipsilateral hippocampus. TSA did not affect IA extinction or reconsolidation. These results indicate that HDACis can increase IA memory retention when given into the hippocampus, and, most importantly, BLA activity is necessary for enabling HDACi-induced influences on memory formation.