275 research outputs found
Benthic microbial communities of coastal terrestrial and ice shelf Antarctic meltwater ponds.
The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to examine variation between pond microbial communities and their biogeography. Geochemically comparable but geomorphologically distinct ponds were selected from Bratina Island (ice shelf) and Miers Valley (terrestrial) (<40 km between study sites), and community structure within ponds was compared using DNA fingerprinting and pyrosequencing of 16S rRNA gene amplicons. More than 85% of total sequence reads were shared between pooled benthic communities at different locations (OTU0.05), which in combination with favorable prevailing winds suggests aeolian regional distribution. Consistent with previous findings Proteobacteria and Bacteroidetes were the dominant phyla representing over 50% of total sequences; however, a large number of other phyla (21) were also detected in this ecosystem. Although dominant Bacteria were ubiquitous between ponds, site and local selection resulted in heterogeneous community structures and with more than 45% of diversity being pond specific. Potassium was identified as the most significant contributing factor to the cosmopolitan community structure and aluminum to the location unique community based on a BEST analysis (Spearman's correlation coefficient of 0.632 and 0.806, respectively). These results indicate that the microbial communities in meltwater ponds are easily dispersed regionally and that the local geochemical environment drives the ponds community structure
Enhanced Tissue Integration During Cartilage RepairIn VitroCan Be Achieved by Inhibiting Chondrocyte Death at the Wound Edge
Objective: Experimental wounding of articular cartilage results in cell death at the lesion edge. The objective of this study was to investigate whether inhibition of this cell death results in enhanced integrative cartilage repair. Methods: Bovine articular cartilage discs (6mm) were incubated in media containing inhibitors of necrosis (Necrostatin-1, Nec-1) or apoptosis (Z-VAD-FMK, ZVF) before cutting a 3mm inner core. This core was left in situ to create disc/ring composites, cultured for up to 6 weeks with the inhibitors, and analyzed for cell death, sulfated glycosaminoglycan release, and tissue integration. Results: Creating the disc/ring composites resulted in a significant increase in necrosis. ZVF significantly reduced necrosis and apoptosis at the wound edge. Nec-1 reduced necrosis. Both inhibitors reduced the level of wound-induced sulfated glycosaminoglycan loss. Toluidine blue staining and electron microscopy of cartilage revealed significant integration of the wound edges in disc/ring composites treated with ZVF. Nec-1 improved integration, but to a lesser extent. Push-out testing revealed that ZVF increased adhesive strength compared to control composites. Conclusions: This study shows that treatment of articular cartilage with cell death inhibitors during wound repair increases the number of viable cells at the wound edge, prevents matrix loss, and results in a significant improvement in cartilage-cartilage integration
Retroviral-mediated overexpression of human bone morphogenetic protein 2 affects human mesenchymal stem cells during monolayer proliferation: A cautionary note
Background: Retroviral vectors are commonly used for gene transfer
applications and they represent an effective way to provide a sustained
delivery of a bioactive factor in basic research and tissue engineering
applications. Cells that have been transduced with retroviral vectors
ex vivo are usually amplified on tissue culture plastic, for a
prolonged period of time, in order to obtain sufficient cell numbers
prior to the experiment of interest. However, the effect of the
transgene product on the transduced cells, during this period of time,
is rarely, if ever, investigated. The current study investigated if
transduction with a VSG.G pseudotyped retroviral vector expressing
human bone morphogenetic protein 2 (Rv.BMP-2) influences the gene
expression profile of human bone marrow-derived mesenchymal stem cells
(hMSCs) during monolayer proliferation. hMSCs that have been transduced
with a VSG.G pseudotyped retroviral vector expressing enhanced green
fluorescent protein (Rv.eGFP) served as controls. Results: It was
confirmed that Rv.BMP-2 transduced hMSCs produce detectable amounts of
bone morphogenetic protein 2 (BMP-2). Gene expression analysis revealed
that the hypertrophic marker collagen X was down-regulated by
approximately 50% and the chondrogenic marker Aggrecan was elevated
almost 9-fold in Rv.BMP-2 transduced hMSCs if compared to Rv.eGFP
transduced control cells. Interestingly, the same changes in gene
expression were detected when hMSCs were exposed to 100 ng/ml of
recombinant human BMP-2 and their gene expression profile was compared
to control hMSC. Again, collagen X message was down-regulated and
Aggrecan message was up-regulated. Conclusion: These results indicate
that, when using integrating vectors and then expanding the cells after
transduction, controls need to be carefully planned to ensure the
results obtained during the 3D experiments are not due to artefacts
created in response to the different cell proliferation conditions
employed
Distinct mesenchymal progenitor cell subsets in the adult human synovium
Objective. To analyse the heterogeneity at the single-cell level of human mesenchymal progenitor cells from SM. Methods. Cell populations were enzymatically released from the knee joint synovium of adult human individuals. Single cell-derived clonal populations were obtained by limiting dilution and serially passaged to determine growth rates. Phenotypic analysis was carried out by flow cytometry. Replicative senescence was assessed by the senescence-associated β-galactosidase staining. Telomere lengths were determined semiquantitatively by Southern blotting. Telomerase activity was measured using a real-time quantitative telomerase repeat amplification procedure. Culture-expanded clonal populations were subjected to in vitro differentiation assays to investigate their mesenchymal multipotency. Results. The 50 clones analysed displayed wide variations in the proliferation rates, even within the same donor sample. The time taken to reach 20 population doublings ranged from 44 to 130 days. The phenotype of the clones tested was compatible with that of mesenchymal stem cells. Mean telomere lengths ranged from 5.2 to 10.9 kb with positive linear trend with telomerase activity, but no correlation with proliferative rates or cell senescence. All clones tested were capable of chondrogenic and osteogenic differentiation, though with large variability in potency. In contrast, only 30% of the clones were adipogenic. Conclusions. We report for the first time the co-existence, within the synovium, of progenitor cell subsets with distinct mesenchymal differentiation potency. Our findings further emphasize the need for strategies to purify cell populations with the clinically desired tissue formation potential
An integrated proteomic and transcriptomic signature of the failing right ventricle in monocrotaline induced pulmonary arterial hypertension in male rats
Aim: Pulmonary arterial hypertension (PAH) is an obstructive pulmonary vasculopathy that results in death from right ventricular failure (RVF). There is limited understanding of the molecular mechanisms of RVF in PAH. Methods: In a PAH-RVF model induced by injection of adult male rats with monocrotaline (MCT; 60Â mg/kg), we performed mass spectrometry to identify proteins that change in the RV as a consequence of PAH induced RVF. Bioinformatic analysis was used to integrate our previously published RNA sequencing data from an independent cohort of PAH rats. Results: We identified 1,277 differentially regulated proteins in the RV of MCT rats compared to controls. Integration of MCT RV transcriptome and proteome data sets identified 410 targets that are concordantly regulated at the mRNA and protein levels. Functional analysis of these data revealed enriched functions, including mitochondrial metabolism, cellular respiration, and purine metabolism. We also prioritized 15 highly enriched protein:transcript pairs and confirmed their biological plausibility as contributors to RVF. We demonstrated an overlap of these differentially expressed pairs with data published by independent investigators using multiple PAH models, including the male SU5416-hypoxia model and several male rat strains. Conclusion: Multiomic integration provides a novel view of the molecular phenotype of RVF in PAH which includes dysregulation of pathways involving purine metabolism, mitochondrial function, inflammation, and fibrosis
A useful savagery: The invention of violence in nineteenth-century England
âA Useful Savagery: The Invention of Violence in Nineteenth-Century Englandâ considers a particular configuration of attitudes toward violence that emerged in the early decades of the nineteenth century. As part of a longer-term process of emerging âsensibilities,â violence was, seemingly paradoxically, âinventedâ as a social issue while concurrently relocated in the âcivilisedâ imagination as an anti-social feature mainly of âsavageâ working-class life. The dominant way this discourse evolved was through the creation of a narrative that defined âcivilisationâ in opposition to the presumed âsavageryâ of the working classes. Although the refined classes were often distanced from the physical experience of violence, concern with violence and brutality became significant parts of social commentary aimed at a middle-class readership. While stridently redefining themselves in opposition to âbrutality,â one of the purposes of this literature was to create a new middle class and justify the expansion of state power. By the closing decades of the nineteenth century, as the working classes adopted tenets of Victorian respectability, a proliferating number of social and psychological âothersâ were identified against which âcivilisedâ thought could define itself
Evolved Gas Analyses of Sedimentary Rocks and Eolian Sediment in Gale Crater, Mars: Results of the Curiosity Rover's Sample Analysis at Mars Instrument.
The Sample Analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, SO2, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. The SAM-EGA heats samples to 870C and measures evolved gas releases as function of temperature. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. CO2 and CO evolved at similar temperatures suggesting that as much as 2373 820 gC/g may occur as organic carbon in the Gale Crater rock record while relatively higher temperature CO2 detections are consistent with carbonate (<0.70 0.1 wt % CO3). Evolved NO amounts up to 0.06 0.03 wt % NO3 have been detected while O2 detections suggests chlorates and/or perchlorates (0.05 to 1.05 wt % ClO4) are present. Evolution of SO2 indicated the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 - 2.5 wt% H2O) was consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2S detections suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population
Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian : Insights From the Mars Science Laboratory
We acknowledge the NASA Mars Science Laboratory Program, Centre National d'Ătudes Spatiales, the Universidad Nacional AutĂłnoma de MĂŠxico (PAPIIT IN109416, IN111619, and PAPIME PE103216), and the Consejo Nacional de Ciencia y TecnologĂa de MĂŠxico (CONACyT 220626) for their support. We thank Fred Calef for constructing Figure 4 and appreciate the interest and support received from John P. Grotzinger and Joy A. Crisp throughout the Curiosity mission. The authors are grateful to the SAM and MSL teams for successful operation of the SAM instrument and the Curiosity rover. The data used in this paper are listed in the supporting information, figures, and references. SAM Data contained in this paper are publicly available through the NASA Planetary Data System at http://pdsâgeosciences.wustl.edu/missions/msl/sam.htm. We would like to express gratitude to PierreâYves Meslin from the Research Institute in Astrophysics and Planetology at Toulouse, France, and five anonymous reviewers whose comments/suggestions on earlier drafts helped improve and clarify this manuscript. The authors declare no conflicts of interests.Peer reviewedPublisher PD
Identification and Clonal Characterisation of a Progenitor Cell Sub-Population in Normal Human Articular Cartilage
Background: Articular cartilage displays a poor repair capacity. The aim of cell-based therapies for cartilage defects is to repair damaged joint surfaces with a functional replacement tissue. Currently, chondrocytes removed from a healthy region of the cartilage are used but they are unable to retain their phenotype in expanded culture. The resulting repair tissue is fibrocartilaginous rather than hyaline, potentially compromising long-term repair. Mesenchymal stem cells, particularly bone marrow stromal cells (BMSC), are of interest for cartilage repair due to their inherent replicative potential. However, chondrocyte differentiated BMSCs display an endochondral phenotype, that is, can terminally differentiate and form a calcified matrix, leading to failure in long-term defect repair. Here, we investigate the isolation and characterisation of a human cartilage progenitor population that is resident within permanent adult articular cartilage.
Methods and Findings: Human articular cartilage samples were digested and clonal populations isolated using a differential adhesion assay to fibronectin. Clonal cell lines were expanded in growth media to high population doublings and karyotype analysis performed. We present data to show that this cell population demonstrates a restricted differential potential during chondrogenic induction in a 3D pellet culture system. Furthermore, evidence of high telomerase activity and maintenance of telomere length, characteristic of a mesenchymal stem cell population, were observed in this clonal cell population. Lastly, as proof of principle, we carried out a pilot repair study in a goat in vivo model demonstrating the ability of goat cartilage progenitors to form a cartilage-like repair tissue in a chondral defect.
Conclusions: In conclusion, we propose that we have identified and characterised a novel cartilage progenitor population resident in human articular cartilage which will greatly benefit future cell-based cartilage repair therapies due to its ability to maintain chondrogenicity upon extensive expansion unlike full-depth chondrocytes that lose this ability at only seven population doublings
INCITE: A randomised trial comparing constraint induced movement therapy and bimanual training in children with congenital hemiplegia
Background: Congenital hemiplegia is the most common form of cerebral palsy (CP) accounting for 1 in 1300 live births. These children have limitations in capacity to use the impaired upper limb and bimanual coordination deficits which impact on daily activities and participation in home, school and community life. There are currently two diverse intensive therapy approaches. Traditional therapy has adopted a bimanual approach (BIM training) and recently, constraint induced movement therapy (CIMT) has emerged as a promising unimanual approach. Uncertainty remains about the efficacy of these interventions and characteristics of best responders. This study aims to compare the efficacy of CIMT to BIM training to improve outcomes across the ICF for school children with congenital hemiplegia
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