Bioactivity and antimicrobial properties of chitosan-tobermorite membranes

Tobermorite (Ca5Si6O16(OH)2.4H2O) is a layered calcium silicate hydrate phase whose bioactivity and biocompatibility with respect to bone and dental tissues are documented. Chitosan is a biodegradable mucopolysaccharide derivative that has been evaluated as a tissue scaffold material for the in situ regeneration of bone and periodontal structures. Recent studies have shown that tobermorite-chitosan composites are potential candidates for use as biodegradable guided tissue regeneration (GTR) membranes [2,3]. During the GTR process, a membrane is used to isolate the exposed root surface from invasive epithelial and gingival tissues in order to enable the slow-growing periodontal ligament and hard tissues to regenerate. Resistance to potentially pathogenic oral bacteria is a highly desirable property of GTR membranes which are prone to biomaterial-centred infection. Silver (Ag+), copper (Cu2+) and gallium (Ga3+) ions are reported to confer antimicrobial activity when incorporated into bioactive materials [1,4,5]. In the present study, tobermorite was synthesised and ion-exchanged with Ag+, Cu2+ or Ga3+ ions. The in vitro bioactivity and antibacterial properties of solvent-cast tobermorite-chitosan composite membranes were then evaluated with respect to their potential use as GTR membranes to repair damaged periodontal structures

Copper- and zinc-bearing composite membranes for periodontal repair

Periodontitis (inflammation and destruction of the tooth attachment apparatus) is one of the most widespread diseases in the world. Polymer-bioactive glass composite membranes can be used for the guided tissue regeneration (GTR) of diseased periodontal structures. GTR involves the placement of the membrane to exclude soft epithelial and gingival tissues from the exposed tooth in order to facilitate the regeneration of the more slow-growing periodontal ligament and hard tissues. Bioactive glasses incorporating antimicrobial ions such as silver, zinc and copper have been shown to resist biomaterial-centred infection; although, the presence of these metal ions is reported to reduce bioactivity in some instances. Chitosan, a biodegradable carbohydrate polymer, is a popular choice for GTR membranes as its structure resembles that of bone extracellular matrix. In the present study, copper- and/or zinc-bearing bioactive glasses were prepared by the sol-gel process and incorporated into chitosan membranes by solvent-casting. The in vitro bioactivity and degradation rates of the chitosan-bioactive glass membranes were evaluated with respect to their potential use as GTR membranes

POP-type ligands : Variable coordination and hemilabile behaviour

Hemilabile ligands – ligands containing two or more potential donors to a metal centre, of which one or more can dissociate – have the ability to provide a transition metal complex with open coordination sites at which reactivity can occur, or stabilise low coordinate intermediates along reaction pathways. POP-type ligands and in particular POP, Xantphos, DBFphos and DPEphos-based ligands contain three possible binding sites: two phosphines and an ether linker, thus have the potential to show κ1-, κ2- or κ3-binding modes. This review summarises the examples where POP-type ligands display hemilabile, or closely related variable coordination, characteristics in either synthesis or catalysis

Exploring Cosmic Origins with CORE: Cosmological Parameters

We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

How to stop wing dieback with bat wing injuries

Unfortunately most of Australia's flying-foxes are listed as vulnerable, largely due to habitat loss and colony destruction. Both of these lead to increased interaction with humans and, inevitably, result in injuries. Specific causes of injuries vary with the location and the time of year, however in Sydney alone, some typical per annum figures for the Grey-headed Flying-fox 'Pteropus poliocephalus' (GHFF) are: • power line 17% (78% fatal); • miscellaneous physical injury 17%; • net caught 17% (in country areas this is by barbed wire instead); • less than half are released and a quarter are euthanised

Decision-making experiences of health professionals in withdrawing treatment for children and young people: A qualitative study

Objective: To explore factors that influence professionals in deciding whether to withdraw treatment from a child and how decision making is managed amongst professionals as an individual and as a team. Study Design: Semi-structured interviews were conducted with a purposive sample of health professionals working at a UK Children's Hospital, with children with life-limiting illnesses whose treatment has been withdrawn. Data were transcribed verbatim, anonymized and analysed using a thematic framework method. Results: A total of 15 participants were interviewed. Five interrelated themes with associated subthemes were generated to help understand the experiences of health professionals in decision making on withdrawing a child's treatment: (1) understanding the child's best interests, (2) multidisciplinary approach, (3) external factors, (4) psychological well-being and (5) recommendations to support shared decision making. Conclusion: A shared decision-making approach should be adopted to support professionals, children and their families to make decisions collectively

A 3D motion analysis study comparing the effectiveness of cervical spine orthoses at restricting spinal motion through physiological range

Objective: To compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars at restricting cervical spine movement in the sagittal, coronal and axial planes. Methods: Nineteen healthy volunteers (12 female, 7 male) were recruited to the study. Collars were fitted by an approved physiotherapist. Eight ProReflex (Qualisys, Sweden) infrared cameras were used to track the movement of retro-reflective marker clusters placed in predetermined positions on the head and trunk. 3D kinematic data were collected during forward flexion, extension, lateral bending and axial rotation from uncollared to collared subjects. The physiological range of motion in the three planes was analysed using the Qualisys Track Manager System. Results: The Aspen and Philadelphia were significantly more effective at restricting flexion/extension than the Vista (p < 0.001), Miami-J (p < 0.001 and p < 0.01) and Miami-J Advanced (p < 0.01 and p < 0.05). The Aspen was significantly more effective at restricting rotation than the Vista (p < 0.001) and the Miami-J (p < 0.05). The Vista was significantly the least effective collar at restricting lateral bending (p < 0.001). Conclusion: Our motion analysis study found the Aspen collar to be superior to the other collars when measuring restriction of movement of the cervical spine in all planes, particularly the sagittal and transverse planes, while the Aspen Vista was the least effective collar