Efficacy and cost-effectiveness of nutritional intervention in elderly after hip fracture: design of a randomized controlled trial

Background: Hip fracture patients often have an impaired nutritional status at the time of fracture, which can result in a higher complication rate, prolonged rehabilitation time and increased mortality. A study was designed to evaluate the effect of nutritional intervention on nutritional status, functional status, total length of stay, postoperative complications and cost-effectiveness. Methods: Open-labelled, multi-centre, randomized controlled trial in hip fracture patients aged 55 years and above. The intervention group receives dietetic counselling (by regular home visits and telephone calls) and oral nutritional supplementation for three months after surgery. The control group receives usual dietetic care as provided by the hospital. Outcome assessment is performed at three and six months after hip fracture. Discussion: Patient recruitment has started in July 2007 and has ended in December 2009. First results are expected in 2011. Trial registration: ClinicalTrials.gov NCT00523575Mechanical, Maritime and Materials Engineerin

Silent chromatin at the middle and ends: lessons from yeasts

Eukaryotic centromeres and telomeres are specialized chromosomal regions that share one common characteristic: their underlying DNA sequences are assembled into heritably repressed chromatin. Silent chromatin in budding and fission yeast is composed of fundamentally divergent proteins tat assemble very different chromatin structures. However, the ultimate behaviour of silent chromatin and the pathways that assemble it seem strikingly similar among Saccharomyces cerevisiae (S. cerevisiae), Schizosaccharomyces pombe (S. pombe) and other eukaryotes. Thus, studies in both yeasts have been instrumental in dissecting the mechanisms that establish and maintain silent chromatin in eukaryotes, contributing substantially to our understanding of epigenetic processes. In this review, we discuss current models for the generation of heterochromatic domains at centromeres and telomeres in the two yeast species

Promoter directionality is controlled by U1 snRNP and polyadenylation signals

Transcription of the mammalian genome is pervasive, but productive transcription outside of protein-coding genes is limited by unknown mechanisms1. In particular, although RNA polymerase II (RNAPII) initiates divergently from most active gene promoters, productive elongation occurs primarily in the sense-coding direction2, 3, 4. Here we show in mouse embryonic stem cells that asymmetric sequence determinants flanking gene transcription start sites control promoter directionality by regulating promoter-proximal cleavage and polyadenylation. We find that upstream antisense RNAs are cleaved and polyadenylated at poly(A) sites (PASs) shortly after initiation. De novo motif analysis shows PAS signals and U1 small nuclear ribonucleoprotein (snRNP) recognition sites to be the most depleted and enriched sequences, respectively, in the sense direction relative to the upstream antisense direction. These U1 snRNP sites and PAS sites are progressively gained and lost, respectively, at the 5′ end of coding genes during vertebrate evolution. Functional disruption of U1 snRNP activity results in a dramatic increase in promoter-proximal cleavage events in the sense direction with slight increases in the antisense direction. These data suggest that a U1–PAS axis characterized by low U1 snRNP recognition and a high density of PASs in the upstream antisense region reinforces promoter directionality by promoting early termination in upstream antisense regions, whereas proximal sense PAS signals are suppressed by U1 snRNP. We propose that the U1–PAS axis limits pervasive transcription throughout the genome.United States. Public Health Service (grant RO1-GM34277)United States. Public Health Service (grant R01-CA133404)National Cancer Institute (U.S.) (Cancer Center Support (core) grant P30-CA14051)National Institutes of Health (U.S.)National Institute of General Medical Sciences (U.S.) (Public Health Service research grant (GM-085319))Howard Hughes Medical Institute (International Student Research fellow

Biosphere-atmosphere exchange of ammonia

Substantial progress has been made in the last eight years in the understanding and quantification of ammonia exchange between the atmosphere and biosphere. Much of the work has been linked to the joint EC/EUROTRAC subproject BIATEX (BIosphere ATmosphere EXchange), which has served as the main European forum for work in this area. In the mid-1980s there was still much confusion and uncertainty over the rate and direction of ammonia fluxes with different ecosystems; although the results of isolated studies were available, there was no clear overview of the key factors affecting ammonia fluxes. Work since that time has highlighted the dominant effects of ecosystem type and management, as well as humidity and wetness, on ammonia exchange. Ammonia is a key component of plant metabolism, so that ammonia emission may occur from plants in relation to nitrogen nutrition and plant growth stage. In contrast, ammonia is highly soluble and may be efficiently captured by leaf cuticles and surface w etness allowing large deposition velocities. The consequence is that ammonia exchange is bi-directional over agricultural ecosystems, though for most semi-natural ecosystems dry deposition dominates, being a significant component of the total atmospheric nitrogen input. The work within BIATEX has focused in more detail on the processes controlling these differences and, using the results of both micrometeorological and controlled environment measurements, has developed new models that are able to provide the synthesis necessary to predict ammonia fluxes. Long term and regional estimates of ammonia net exchange are still uncertain, though the models developed now provide the necessary framework to guide future measurements