214 research outputs found
A miniaturized bioreactor system for the evaluation of cell interaction with designed substrates in perfusion culture
In tissue engineering, the chemical and topographical cues within three-dimensional (3D) scaffolds are normally tested using static cell cultures but applied directly to tissue cultures in perfusion bioreactors. As human cells are very sensitive to the changes of culture environment, it is essential to evaluate the performance of any chemical, and topographical cues in a perfused environment before they are applied to tissue engineering. Thus the aim of this research was to bridge the gap between static and perfusion cultures by addressing the effect of perfusion on cell cultures within 3D scaffolds. For this we developed a scale down bioreactor system, which allows to evaluate the effectiveness of various chemical and topographical cues incorporated into our previously developed tubular ε-polycaprolactone scaffold under perfused conditions. Investigation of two exemplary cell types (fibroblasts and cortical astrocytes) using the miniaturized bioreactor indicated that: (1) quick and firm cell adhesion in 3D scaffold was critical for cell survival in perfusion culture compared with static culture, thus cell seeding procedures for static cultures might not be applicable. Therefore it was necessary to re-evaluate cell attachment on different surfaces under perfused conditions before a 3D scaffold was applied for tissue cultures, (2) continuous medium perfusion adversely influenced cell spread and survival, which could be balanced by intermittent perfusion, (3) micro-grooves still maintained its influences on cell alignment under perfused conditions, while medium perfusion demonstrated additional influence on fibroblast alignment but not on astrocyte alignment on grooved substrates. This research demonstrated that the mini-bioreactor system is crucial for the development of functional scaffolds with suitable chemical and topographical cues by bridging the gap between static culture and perfusion culture
Biodiversity and Ecosystem Function in the Gulf of Maine: Pattern and Role of Zooplankton and Pelagic Nekton
This paper forms part of a broader overview of biodiversity of marine life in the Gulf of Maine area (GoMA), facilitated by the GoMA Census of Marine Life program. It synthesizes current data on species diversity of zooplankton and pelagic nekton, including compilation of observed species and descriptions of seasonal, regional and cross-shelf diversity patterns. Zooplankton diversity in the GoMA is characterized by spatial differences in community composition among the neritic environment, the coastal shelf, and deep offshore waters. Copepod diversity increased with depth on the Scotian Shelf. On the coastal shelf of the western Gulf of Maine, the number of higher-level taxonomic groups declined with distance from shore, reflecting more nearshore meroplankton. Copepod diversity increased in late summer, and interdecadal diversity shifts were observed, including a period of higher diversity in the 1990s. Changes in species diversity were greatest on interannual scales, intermediate on seasonal scales, and smallest across regions, in contrast to abundance patterns, suggesting that zooplankton diversity may be a more sensitive indicator of ecosystem response to interannual climate variation than zooplankton abundance. Local factors such as bathymetry, proximity of the coast, and advection probably drive zooplankton and pelagic nekton diversity patterns in the GoMA, while ocean-basin-scale diversity patterns probably contribute to the increase in diversity at the Scotian Shelf break, a zone of mixing between the cold-temperate community of the shelf and the warm-water community offshore. Pressing research needs include establishment of a comprehensive system for observing change in zooplankton and pelagic nekton diversity, enhanced observations of underknown\u27\u27 but important functional components of the ecosystem, population and metapopulation studies, and development of analytical modeling tools to enhance understanding of diversity patterns and drivers. Ultimately, sustained observations and modeling analysis of biodiversity must be effectively communicated to managers and incorporated into ecosystem approaches for management of GoMA living marine resources
Blind Test of Methods for Obtaining 2-D Near-Surface Seismic Velocity Models from First-Arrival Traveltimes
Seismic refraction methods are used in environmental and engineering studies to image the
shallow subsurface. We present a blind test of inversion and tomographic refraction analysis
methods using a synthetic first-arrival-time dataset that was made available to the community in
2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry
and the data’s frequency and added noise. Fourteen estimated models were determined by ten
participants using eight different inversion algorithms, with the true model unknown to the
participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated
models are generally consistent in terms of their large-scale features, demonstrating the
robustness of refraction data inversion in general, and the eight inversion algorithms in
particular. When compared to the true model, all of the estimated models contain a smooth
expression of its two main features: a large offset in the bedrock and the top of a steeply dipping
low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and
other fine-scale features, in accord with conventional wisdom. Together, the results support
confidence in the reliability and robustness of modern refraction inversion and tomographic
Methods
Advancing Research on the Complex Interrelations Between Atrial Fibrillation and Heart Failure A Report From a US National Heart, Lung, and Blood Institute Virtual Workshop
The interrelationships between atrial fibrillation (AF) and heart failure (HF) are complex and poorly understood, yet the number of patients with AF and HF continues to increase worldwide. Thus, there is a need for initiatives that prioritize research on the intersection between AF and HF. This article summarizes the proceedings of a virtual workshop convened by the US National Heart, Lung, and Blood Institute to identify important research opportunities in AF and HF. Key knowledge gaps were reviewed and research priorities were proposed for characterizing the pathophysiological overlap and deleterious interactions between AF and HF; preventing HF in people with AF; preventing AF in individuals with HF; and addressing symptom burden and health status outcomes in AF and HF. These research priorities will hopefully help inform, encourage, and stimulate innovative, cost-efficient, and transformative studies to enhance the outcomes of patients with AF and HF
Phylogeny and ecology of the ubiquitous saprobe Cladosporium sphaerospermum, with descriptions of seven new species from hypersaline environments
Saprobic Cladosporium isolates morphologically similar to C.
sphaerospermum are phylogenetically analysed on the basis of DNA
sequences of the ribosomal RNA gene cluster, including the internal
transcribed spacer regions ITS1 and ITS2, the 5.8S rDNA (ITS) and the small
subunit (SSU) rDNA as well as β-tubulin and actin gene introns and exons.
Most of the C. sphaerospermum-like species show halotolerance as a
recurrent feature. Cladosporium sphaerospermum, which is
characterised by almost globose conidia, is redefined on the basis of its
ex-neotype culture. Cladosporium dominicanum, C.
psychrotolerans, C. velox, C. spinulosum and C.
halotolerans, all with globoid conidia, are newly described on the basis
of phylogenetic analyses and cryptic morphological and physiological
characters. Cladosporium halotolerans was isolated from hypersaline
water and bathrooms and detected once on dolphin skin. Cladosporium
dominicanum and C. velox were isolated from plant material and
hypersaline water. Cladosporium psychrotolerans, which grows well at
4 °C but not at 30 °C, and C. spinulosum, having
conspicuously ornamented conidia with long digitate projections, are currently
only known from hypersaline water. We also newly describe C. salinae
from hypersaline water and C. fusiforme from hypersaline water and
animal feed. Both species have ovoid to ellipsoid conidia and are therefore
reminiscent of C. herbarum. Cladosporium langeronii (=
Hormodendrum langeronii) previously described as a pathogen on human
skin, is halotolerant but has not yet been recorded from hypersaline
environments
Chronic mucocutaneous candidiasis in APECED or thymoma patients correlates with autoimmunity to Th17-associated cytokines
Chronic mucocutaneous candidiasis (CMC) is frequently associated with T cell immunodeficiencies. Specifically, the proinflammatory IL-17A–producing Th17 subset is implicated in protection against fungi at epithelial surfaces. In autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED, or autoimmune polyendocrine syndrome 1), CMC is often the first sign, but the underlying immunodeficiency is a long-standing puzzle. In contrast, the subsequent endocrine features are clearly autoimmune, resulting from defects in thymic self-tolerance induction caused by mutations in the autoimmune regulator (AIRE). We report severely reduced IL-17F and IL-22 responses to both Candida albicans antigens and polyclonal stimulation in APECED patients with CMC. Surprisingly, these reductions are strongly associated with neutralizing autoantibodies to IL-17F and IL-22, whereas responses were normal and autoantibodies infrequent in APECED patients without CMC. Our multicenter survey revealed neutralizing autoantibodies against IL-17A (41%), IL-17F (75%), and/ or IL-22 (91%) in >150 APECED patients, especially those with CMC. We independently found autoantibodies against these Th17-produced cytokines in rare thymoma patients with CMC. The autoantibodies preceded the CMC in all informative cases. We conclude that IL-22 and IL-17F are key natural defenders against CMC and that the immunodeficiency underlying CMC in both patient groups has an autoimmune basis
The great screen anomaly—a new frontier in product discovery through functional metagenomics
Functional metagenomics, the study of the collective genome of a microbial community by expressing it in a foreign host, is an emerging field in biotechnology. Over the past years, the possibility of novel product discovery through metagenomics has developed rapidly. Thus, metagenomics has been heralded as a promising mining strategy of resources for the biotechnological and pharmaceutical industry. However, in spite of innovative work in the field of functional genomics in recent years, yields from function-based metagenomics studies still fall short of producing significant amounts of new products that are valuable for biotechnological processes. Thus, a new set of strategies is required with respect to fostering gene expression in comparison to the traditional work. These new strategies should address a major issue, that is, how to successfully express a set of unknown genes of unknown origin in a foreign host in high throughput. This article is an opinionating review of functional metagenomic screening of natural microbial communities, with a focus on the optimization of new product discovery. It first summarizes current major bottlenecks in functional metagenomics and then provides an overview of the general metagenomic assessment strategies, with a focus on the challenges that are met in the screening for, and selection of, target genes in metagenomic libraries. To identify possible screening limitations, strategies to achieve optimal gene expression are reviewed, examining the molecular events all the way from the transcription level through to the secretion of the target gene product
Radiation exposure in X-ray-based imaging techniques used in osteoporosis
Recent advances in medical X-ray imaging have enabled the development of new techniques capable of assessing not only bone quantity but also structure. This article provides (a) a brief review of the current X-ray methods used for quantitative assessment of the skeleton, (b) data on the levels of radiation exposure associated with these methods and (c) information about radiation safety issues. Radiation doses associated with dual-energy X-ray absorptiometry are very low. However, as with any X-ray imaging technique, each particular examination must always be clinically justified. When an examination is justified, the emphasis must be on dose optimisation of imaging protocols. Dose optimisation is more important for paediatric examinations because children are more vulnerable to radiation than adults. Methods based on multi-detector CT (MDCT) are associated with higher radiation doses. New 3D volumetric hip and spine quantitative computed tomography (QCT) techniques and high-resolution MDCT for evaluation of bone structure deliver doses to patients from 1 to 3 mSv. Low-dose protocols are needed to reduce radiation exposure from these methods and minimise associated health risks
Improving risk management for violence in mental health services: a multimethods approach
contractual_start_date: 07-2008 editorial_review_begun: 07-2014 accepted_for_publication: 06-2015contractual_start_date: 07-2008 editorial_review_begun: 07-2014 accepted_for_publication: 06-2015contractual_start_date: 07-2008 editorial_review_begun: 07-2014 accepted_for_publication: 06-2015contractual_start_date: 07-2008 editorial_review_begun: 07-2014 accepted_for_publication: 06-201
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