To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
To date, Ireland has been a leading light in the provision of youth mental health services. However, cognisant of the efforts of governmental and non-governmental agencies working in youth mental health, there is much to be done. Barriers into care as well as discontinuity of care across the spectrum of services remain key challenges. This editorial provides guidance for the next stage of development in youth mental care and support that will require significant national engagement and resource investment.
Objectives: With comparable baseline performance on executive functions (EF) and memory between Alzheimer’s disease (AD) and behavioral-variant frontotemporal dementia (bvFTD), it is currently unclear if both diseases can be distinguished longitudinally on these measures reliably. Methods: A total of 111 participants (33 AD, 31 bvFTD, and 47 controls) were followed-up annually over a 4-year period and tested on measures of EF, memory, and orientation. Linear mixed-effect models were constructed using disease severity as a nuisance variable to examine profiles of neuropsychological performance decline. Results: At baseline, overlap in terms of cognitive impairment between bvFTD and AD on multiple EF, memory, and orientation measures was present. Longitudinally, only disinhibition (Hayling total errors) appeared sensitive to discriminating AD from bvFTD; however, only after the first annual follow-up. Subgroup analyses on smaller samples revealed comparable profiles on EF tasks at baseline and over time between bvFTD and AD who presented with impaired EF at presentation, and on memory and orientation tasks between AD and bvFTD who presented with severe amnesia. Conclusions: Our results replicate previous findings showing only moderate discriminability between AD and bvFTD at clinical presentation on EF and memory measures. More importantly, we also show that longitudinal trajectories strongly overlap for both dementias on these measures. Disinhibition emerged as the sole measure that in the long run was significantly more impaired in bvFTD. Future studies should use tests designed to target cortical regions that are specifically impaired in bvFTD, such as the ventromedial prefrontal cortex, to improve the accurate discrimination of these diseases. (JINS, 2017, 23, 34–43)
Radio-wave scattering in the Vela supernova remnant acts as an imperfect lens to resolve the pulsar’s radio emission region. We use this lens to measure the pulsar’s emission region. We suggest that refraction of radiation within the pulsar’s magnetosphere is responsible for the observed size.
Observations of speckles in the scattering disk of the Vela pulsar are presented and speckle techniques for studying and circumventing scattering of radio waves by the turbulent interstellar plasma are discussed. The speckle pattern contains, in a hologrammatic fashion, complete information on the structure of the radio source as well as the distribution of the scattering material. Speckle observations of interstellar scattering of radio waves are difficult because of their characteristically short timescales (≈seconds) and narrow bandwidths (≈kHz). Here, we present first observations, taken at 13 cm wavelength with elements of the SHEVE VLBI network, of speckles in interstellar scattering.
The Wisconsin Plasma Astrophysics Laboratory (WiPAL) is a flexible user facility designed to study a range of astrophysically relevant plasma processes as well as novel geometries that mimic astrophysical systems. A multi-cusp magnetic bucket constructed from strong samarium cobalt permanent magnets now confines a
, fully ionized, magnetic-field-free plasma in a spherical geometry. Plasma parameters of
provide an ideal testbed for a range of astrophysical experiments, including self-exciting dynamos, collisionless magnetic reconnection, jet stability, stellar winds and more. This article describes the capabilities of WiPAL, along with several experiments, in both operating and planning stages, that illustrate the range of possibilities for future users.
An unlinked anonymous study was conducted to estimate the prevalence of hepatitis C virus (HCV) infection in emergency department (ED) attendees at a London Hospital. Nine hundred and ninety-seven samples collected over a 12-day period were tested for HCV antibody (Ab) and reactive samples were further tested for HCV RNA. The HCV seroprevalence was 2·6% (26/997) with 1·2% (12/997) HCV RNA positive. A peak HCV RNA-positive prevalence of 4·8% (3/63) was found in males aged 35–44 years, this was compared to 0% (0/136) in males aged <35 years (P = 0·0614) and 1·4% (4/278) in males aged ⩾45 years (P = 0·2415). Assuming the cost for HCV Ab is £6 and HCV RNA is £40 per test, screening ED attendees aged 25–54 years would cost £360 per viraemic infection and identify 82% of those who were HCV RNA positive, yielding the most favourable cost/benefit ratio. HCV screening of ED attendees aged 25–54 years in this population could be an effective way of identifying patients and limit onward transmission.
Objectives: The aim of this study was to develop a decision support tool to assess the potential benefits and costs of new healthcare interventions.
Methods: The Canadian Partnership Against Cancer (CPAC) commissioned the development of a Cancer Risk Management Model (CRMM)—a computer microsimulation model that simulates individual lives one at a time, from birth to death, taking account of Canadian demographic and labor force characteristics, risk factor exposures, and health histories. Information from all the simulated lives is combined to produce aggregate measures of health outcomes for the population or for particular subpopulations.
Results: The CRMM can project the population health and economic impacts of cancer control programs in Canada and the impacts of major risk factors, cancer prevention, and screening programs and new cancer treatments on population health and costs to the healthcare system. It estimates both the direct costs of medical care, as well as lost earnings and impacts on tax revenues. The lung and colorectal modules are available through the CPAC Web site (www.cancerview.ca/cancerrriskmanagement) to registered users where structured scenarios can be explored for their projected impacts. Advanced users will be able to specify new scenarios or change existing modules by varying input parameters or by accessing open source code. Model development is now being extended to cervical and breast cancers.
Samples of Fe76RE16B8 have been prepared by melt spinning and plasma deposition. The samples were fully saturated by cooling fran 350°C in a 5 kOe field. The room temperature coercivities of these samples are reported and correlated to the microstructures revealed by scanning electron microscopy. Subsequent heat treatments are shown to either increase or decrease the intrinsic coercivities depending upon the solidification rate that each sample experienced.
Purified type I collagen was formed into matrices whose pore sizes were defined on the basis of previous results. The first series of in vitro studies measured the metabolism of chondrocytes grown in matrices with various pore sizes; results revealed that the growth rate was independent of the average matrix pore size, but that ckmdrocyte infiltration throughout the matrix was optimal for pore sizes of 100 to 150 un. In a second series of studies, type I collagen was combined with hyaluranic acid; the HyA/collagen matrices had little effect on chcrdrocyte cell growth versus the collagen matrices. A third set of in vitro studies used collagen matrices incorporating varying cornentrations of insulin-like growth factor. It was found that the IGF-1/collagen matrices can significantly effect the growth and metabolism of the clxrihrocytes. These experiments were vital in establishing the collagen matrix parameters which will be used in subsequent in vivo studies.
A method is described for the production of collagen constructs formed from densely packed, native-banded collagen fibrils. This “Dense Fibrillar Collagen” is formed by concentrating collagen in situ prior to self assembly of the collagen into fibrils. The effect of altering the pH, ionic strength, and osmolarity of the concentrating solution was measured. Increasing the ionic strength and osmolarity of the concentrating solution increased the burst strength of the constructs; increasing the pH from 3.8 to 7.1 reduced the surface fibrillarity, degree of platelet uptake and “short term in vivo thrombogenicity. This construct is being considered as the basis of a small-caliber vascular prosthesis to support guided tissue regeneration.
Spontaneous new bone formation does not occur in the adult calvarium. In humans, cranial defects may require repair for brain protection, headaches or cosmetic. Over the years the search for the ideal cranioplasty material to repair such cranial defects has been extensive. We report an evaluation of alpha plaster of paris as an osteoconductive material in a cat craniectomy defect.
Adult cats of either sex were anesthetized with ketamine/halothane and a 15mm biparietal craniectomy defect created. The right side was filled with alpha plaster of paris and the left served as a control. There were 4 animals in each time cohort and animals were sacrificed at 6 weeks, 6 or 12 months. The cranium was removed, fixed, stained, histologically studied and analysised for the percentage of trabecular bone formation. At all durations the control defects were bridged by proliferative fibrous tissue membrane and less than 1% trabecular bone. At six weeks the plaster of paris filled defects were either totally or nearly totally replaced by new bone formation. The plaster was completely resorbed. At 6 wks there was 28% trabecular bone which increased to 93% at 52 wks. Our experiments demonstrate the oeteoconductive potential of alpha plaster of paris in the adult calvarium. This material needs to be evaluated in humans to ascertain its potential as a biocompatible cranioplasty material.
The coverage of an oxidized Ti-surface by amphoteric OH groups seems to be the driving mechanism for the attachement of bone material to Ti-implants. To contribute to the quantitative and fundamental understanding of this phenomenon, an ab-inito surface method was applied to calculate the electronic structure and energetics of the clean and hydroxylated (110) TiO2 rutile surface. Some of the most important relaxation and reconstruction effects of surface geometries were derived from total energy minimization.
Glass-ceramics (A-W) containing apatite and wollastonite phases have been developed that show good bio-compatibility and rapidly form chemical bonds with living bone. The glass-ceramic (A-W) was implanted with 200 keV Zr and Ar ions at doses of 1E15 to 1E17 ions/sq.cm. It was found that the Zr ion implantation was effective for obtaining high mechanical strength in simulated body fluid. The increase of the mechanical strength can be considered to be due to the formation of Zr and O bonds by ion implantation. The bioactivity of the implanted ceramics remained, and was improved after soaking in the simulated body fluid. In the case of Ar ion implantation, the fracture strength was not improved. However, the bioactivity was strong and improved with increase of the time soaked in the simulated body fluid.
Primary rat bone marrow cells were cultured on bacteriological grade polystyrene dishes which had been treated in selected areas with concentrated sulphuric acid. X-ray photoelectron spectroscopy, angle-resolved and imaging modes, and atomic force microscopy showed that the acid treatment brought about both chemical and topographical changes in the substratum surface. While the bone marrow cells attached to both treated and untreated areas of the surfaces of the dishes, the distribution of early mineralized extracellular matrix in these areas was reproducibily different. Thus, using extracellular matrix deposition as a marker, modification of the polymer surface resulted in the cells adhering to treated and untreated areas exhibiting different phenotypes.
Because cells can recognize and attach to short synthetic peptides containing the tripeptide sequence, arg-gly-asp (RGD), we have designed peptides which will spontaneously bind and present an active RGD sequence on biomaterial surfaces. We have analyzed a number of synthetic peptides and fully characterized one which fulfills this functional criteria. This peptide has been named PepTite-2000™. When biomaterials are placed in aqueous buffers containing PepTite-2000, the peptide rapidly binds to the surface and provides a site for cell attachment. Cell attachment occurs to PepTite-2000 coated materials by an RGD dependent mechanism using the αvβ3 integrin. This coating protocol is widely applicable, and the peptide will coat and promote cell attachment to all the commonly used biomaterials we have tested including dacron, teflon, titanium and silicone. Analysis of the soft tissue response to dacron implants coated with PepTite-2000 demonstrates that the coating results in more rapid tissue ingrowth and less giant cell recruitment around the implanted materials. These data demonstrate that PepTite-2000 can be used to modify biomaterial surfaces and present a more “natural” site for cell interactions.
Growth and differentiation of animal cells are influenced by a number of interacting local and circulating protein factors. Several such growth factors, or morphogenetic proteins, that affect hard tissue regeneration and repair have been isolated from bone [1–3]. Bone matrix is a complex milieu consisting of serum, cell, and hydroxyapatite binding proteins, bioactive agents, and other proteins whose functions are not yet known. Most of the growth factors can be dissociated from the decalcified collagen matrix only by using chaotropic solvents such as guanidine hydrochloride or urea .This extraction removes virtually all noncollagenous proteins from the matrix, producing a nonselective portfolio of proteins, of which growth factors are only a small percentage. A series of chromatographic separations are then required to isolate the morphogenetic proteins from the mixture . Recently, a process has been developed that permits selective extraction of certain growth factors from demineralized bone and produces a water-soluble extract of collagenous and noncollagenous proteins. When placed in an orthotopic site in the rat, the extract exhibits pronounced osteogenic activity and has a surface-adherent property that may be exploited in the coating of allograft bone or osteoprosthetic implants to facilitate osseointegration. The objective of this study is to observe the in vivo effects of this extract on proliferation and synthetic activity of cartilage cells of the chick embryo.
An enzyme immunoassay has been developed to semi-quantitate the degree of activation of platelets adhering to biomaterials. The method employs a monoclonal mouse anti-GMP-140 antibody. The glycoprotein GMP-140 is contained in alpha granules of resting platelets and is translocated to the outer membrane of platelets during activation via the thrombin-dependent pathway. A polyclonal anti-mouse IgG peroxidase conjugate is then added and platelet activation can be semi-quantitated by use of a suitable substrate, such as OPD.
The results obtained by this method compare well with scanning electron microscopy, and are shown to be less prone to the misinterpretation often associated with other conventional assay systems such as the determination of platelet adhesion by detection of ATP.
The adhesion and activation of platelets by biomaterials has been compared before and after coating these materials with phosphorylcholine (PC) derivatives. PC, in its form as a headgroup in membrane phosphoglyceride (lecithin) and ceramide (sphingomyelin) is a ubiquitous component of cell membranes, and displays extremely low interaction and binding with plasma proteins such as Factor XII [1,2], complement , fibrinogen [3,2], immunoglobulins  and albumin [2,4].
Using the immunoassay described here activation of platelets is seen to be dramatically reduced after coating surfaces, such as polyethylene, with PC compared with the untreated control. A PCcoated surface should therefore be an ideal starting point for developing tissue-inducing biomaterials. In addition endothelial cells contain GMP-140 in their secretory granules . This would make this assay a potential tool in the investigation of endothelial cell - biomaterial interaction.
Plaster bandages have been found to support bacteria. The sterilization of plaster (calcium sulfate hemihydrate) for use as an implant biomaterial is, therefore, a primary concern. Heat sterilization can significantly alter material properties and the kinetics of plaster hydration. A study has been done of the effects of sterilization by gamma radiation and by ethylene oxide on the hydration rate of plaster. Three hemihydrate bases with differing water requirements and hydration rates were sterilized by each method. Adiabatic temperature rise was used to follow hydration. Five outcomes were measured and analyzed. These outcomes include the induction period, maximum rate of temperature rise (MRR), time to MRR, total temperature rise, and time to maximum temperature. Neither sterilization mode was found to significantly alter the hydration process of any of the plaster bases. From a material property standpoint, either gamma radiation or ethylene oxide treatment is preferred to heat sterization of calcium sulfate hemihydrate.