Xylan decoration patterns and the plant secondary cell wall molecular architecture.

The molecular architecture of plant secondary cell walls is still not resolved. There are several proposed structures for cellulose fibrils, the main component of plant cell walls and the conformation of other molecules is even less well known. Glucuronic acid (GlcA) substitution of xylan (GUX) enzymes, in CAZy family glycosyl transferase (GT)8, decorate the xylan backbone with various specific patterns of GlcA. It was recently discovered that dicot xylan has a domain with the side chain decorations distributed on every second unit of the backbone (xylose). If the xylan backbone folds in a similar way to glucan chains in cellulose (2-fold helix), this kind of arrangement may allow the undecorated side of the xylan chain to hydrogen bond with the hydrophilic surface of cellulose microfibrils. MD simulations suggest that such interactions are energetically stable. We discuss the possible role of this xylan decoration pattern in building of the plant cell wall.We thank Nadine Anders for helpful comments on the manuscript. The work was supported by a Leverhulme Trust Programme Grant : The Centre for Natural Material Innovation and the Biotechnology and Biological Sciences Research Council grant numbers [BB/K005537/1] and [BB/G016240/1].This is the author accepted manuscript. The final version is available from Portland Press via http://dx.doi.org/10.1042/BST2015018

Determining the impacts of hospital cost-sharing on the uninsured near-poor households in Vietnam

Objectives: The study objective was to identify the size of different hospital financing sources for different hospital services and their impact on the uninsured. Methods: A panel dataset of 84 public general hospitals (2005–2008) with cross-section data on hospital activity and hospital revenue was created and used to calculate unit costs of different hospital services by applying multiple regression models. The resulting risk of catastrophic health expenditure (CHE) was estimated based on official income statistics. Results: Average user fees (UF) for outpatient visits and inpatient bed days were US$4.13 and US$20.27, while actual full costs (AFC) were US$8.41 and US$36.66, respectively. These unit costs were 2.5 times higher in hospitals at the central versus the provincial level. UF for surgical inpatient bed days were 3.6 times that of non-surgical treatments (US$47.50 vs. 12.87) and AFC 5.0 times (US$101.72 vs. 20.08). UF accounted for 44.6%-77.9% of the AFC, the rest (22.1%-55.4%) was provided by direct government support (DGS). One surgical inpatient treatment at either central or provincial hospital level and one non-surgical inpatient treatment at central hospital level, immediately pushed uninsured near-poor households at risk of CHE. Conclusions: Around 45% of hospital AFC was paid by DGS, the larger rest by UF. UF have become a great financial burden on the uninsured near-poor households, who have to pay for these out-of-pocket and therefore may not utilize even necessary services. If the rate of DGS were reduced, this would have the effect of increasing UF, but the savings to Government could be spent on subsidizing insurance to ensure that a larger part of the population can cover UF through insurance, especially the near-poor households

Accelerated Growth Plate Mineralization and Foreshortened Proximal Limb Bones in Fetuin-A Knockout Mice

PMCID: PMC3473050This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Low intensity pulsed ultrasonography for fractures: systematic review of randomised controlled trials

Objective To determine the efficacy of low intensity pulsed ultrasonography for healing of fractures

Enhanced Recovery after Intensive Care (ERIC): study protocol for a German stepped wedge cluster randomised controlled trial to evaluate the effectiveness of a critical care telehealth program on process quality and functional outcome

Introduction: Survival after critical illness has noticeably improved over the last decades due to advances in critical care medicine. Besides, there is an increasing number of elderly patients with chronic diseases being treated in the intensive care unit (ICU). More than half of the survivors of critical illness suffer from medium-term or long-term cognitive, psychological and/or physical impairments after ICU discharge, which is recognised as post-intensive care syndrome (PICS). There are evidence-based and consensus-based quality indicators (QIs) in intensive care medicine, which have a positive influence on patients' long-term outcomes if adhered to. Methods and analysis: The protocol of a multicentre, pragmatic, stepped wedge cluster randomised controlled, quality improvement trial is presented. During 3 predefined steps, 12 academic hospitals in Berlin and Brandenburg, Germany, are randomly selected to move in a one-way crossover from the control to the intervention condition. After a multifactorial training programme on QIs and clinical outcomes for site personnel, ICUs will receive an adapted, interprofessional protocol for a complex telehealth intervention comprising of daily telemedical rounds at ICU. The targeted sample size is 1431 patients. The primary objective of this trial is to evaluate the effectiveness of the intervention on the adherence to eight QIs daily measured during the patient's ICU stay, compared with standard of care. Furthermore, the impact on long-term recovery such as PICS-related, patient-centred outcomes including health-related quality of life, mental health, clinical assessments of cognition and physical function, all-cause mortality and cost-effectiveness 3 and 6 months after ICU discharge will be evaluated. Ethics and dissemination: This protocol was approved by the ethics committee of the Charité-Universitätsmedizin, Berlin, Germany (EA1/006/18). The results will be published in a peer-reviewed scientific journal and presented at international conferences. Study findings will also be disseminated via the website (www.eric-projekt.net). Trial registration number: ClinicalTrials.gov Registry (NCT03671447)

Evolution of Xylan Substitution Patterns in Gymnosperms and Angiosperms: Implications for Xylan Interaction with Cellulose.

The interaction between cellulose and xylan is important for the load-bearing secondary cell wall of flowering plants. Based on the precise, evenly spaced pattern of acetyl and glucuronosyl (MeGlcA) xylan substitutions in eudicots, we recently proposed that an unsubstituted face of xylan in a 2-fold helical screw can hydrogen bond to the hydrophilic surfaces of cellulose microfibrils. In gymnosperm cell walls, any role for xylan is unclear, and glucomannan is thought to be the important cellulose-binding polysaccharide. Here, we analyzed xylan from the secondary cell walls of the four gymnosperm lineages (Conifer, Gingko, Cycad, and Gnetophyta). Conifer, Gingko, and Cycad xylan lacks acetylation but is modified by arabinose and MeGlcA. Interestingly, the arabinosyl substitutions are located two xylosyl residues from MeGlcA, which is itself placed precisely on every sixth xylosyl residue. Notably, the Gnetophyta xylan is more akin to early-branching angiosperms and eudicot xylan, lacking arabinose but possessing acetylation on alternate xylosyl residues. All these precise substitution patterns are compatible with gymnosperm xylan binding to hydrophilic surfaces of cellulose. Molecular dynamics simulations support the stable binding of 2-fold screw conifer xylan to the hydrophilic face of cellulose microfibrils. Moreover, the binding of multiple xylan chains to adjacent planes of the cellulose fibril stabilizes the interaction further. Our results show that the type of xylan substitution varies, but an even pattern of xylan substitution is maintained among vascular plants. This suggests that 2-fold screw xylan binds hydrophilic faces of cellulose in eudicots, early-branching angiosperm, and gymnosperm cell walls.This work was supported by the Leverhulme Trust Centre for Natural Material Innovation (MBW, PD), The Low Carbon Energy University Alliance (AL), BBSRC Grant: BB/G016240/1 BBSRC Sustainable Bioenergy Centre cell wall sugars (TT, PD) and the Sao Paulo Research Foundation (RLS, CSP, MSS, TCFG) (Grants 2013/08293-7, 2014/10448-1 and 2015/25031-1)

The pattern of xylan acetylation suggests xylan may interact with cellulose microfibrils as a twofold helical screw in the secondary plant cell wall of Arabidopsis thaliana.

The interaction between xylan and cellulose microfibrils is important for secondary cell wall properties in vascular plants; however, the molecular arrangement of xylan in the cell wall and the nature of the molecular bonding between the polysaccharides are unknown. In dicots, the xylan backbone of β-(1,4)-linked xylosyl residues is decorated by occasional glucuronic acid, and approximately one-half of the xylosyl residues are O-acetylated at C-2 or C-3. We recently proposed that the even, periodic spacing of GlcA residues in the major domain of dicot xylan might allow the xylan backbone to fold as a twofold helical screw to facilitate alignment along, and stable interaction with, cellulose fibrils; however, such an interaction might be adversely impacted by random acetylation of the xylan backbone. Here, we investigated the arrangement of acetyl residues in Arabidopsis xylan using mass spectrometry and NMR. Alternate xylosyl residues along the backbone are acetylated. Using molecular dynamics simulation, we found that a twofold helical screw conformation of xylan is stable in interactions with both hydrophilic and hydrophobic cellulose faces. Tight docking of xylan on the hydrophilic faces is feasible only for xylan decorated on alternate residues and folded as a twofold helical screw. The findings suggest an explanation for the importance of acetylation for xylan-cellulose interactions, and also have implications for our understanding of cell wall molecular architecture and properties, and biological degradation by pathogens and fungi. They will also impact strategies to improve lignocellulose processing for biorefining and bioenergy.The work conducted by TT and NN was supported by a grant from the BBSRC: BB/G016240/1 BBSRC Sustainable Energy Centre Cell Wall Sugars Programme (BSBEC) to PD and DNB. The work of PD was supported by the European Community’s Seventh Framework Programme SUNLIBB (FP7/2007-2013) under the grant agreement #251132. The NMR facility infrastructure was supported by the BBSRC and the Wellcome Trust. TCFG thanks CNPq (Brazil) for a graduate fellowship (grant # 140978/2009-7). MSS thanks CEPROBIO (grant # 490022/2009- 0) and FAPESP for funding (grant #2013/08293-7).This is the accepted version of the following article: "Busse-Wicher, M; Gomes, T.C.F; Tryfona, T; Nikolovski, N; Stott, K; Grantham, N.J; Bolam, D.N; Skaf, M.S; Dupree, P. (2014) "The pattern of xylan acetylation suggests xylan may interact with cellulose microfibrils as a two-fold helical screw in the secondary plant cell wall of Arabidopsis thaliana." The Plant Journal. Accepted article [electronic] 10.1111/tpj.12575", which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/tpj.12575/abstrac