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Find video protocols related to scientific articles indexed in Pubmed.
Scaffold Mean Pore Size Influences Mesenchymal Stem Cell Chondrogenic Differentiation and Matrix Deposition.
Tissue Eng Part A
PUBLISHED: 09-10-2014
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Recent investigations into micro-architecture of scaffolds has revealed that mean pore sizes are cell-type specific and influence cellular shape, differentiation, and extracellular matrix secretion. In this context, the overall goal of this study was to investigate whether scaffold mean pore sizes affect mesenchymal stem cell initial attachment, chondrogenic gene expression, and cartilage-like matrix deposition. Collagen-hyaluronic acid (CHyA) scaffolds, recently developed in our laboratory for in vitro chondrogenesis, were fabricated with three distinct mean pore sizes (94, 130, and 300??m) by altering the freeze-drying technique used. It was evident that scaffolds with the largest mean pore sizes (300??m) stimulated significantly higher cell proliferation, chondrogenic gene expression, cartilage-like matrix deposition, and resulting bulk compressive modulus after in vitro culture, relative to scaffolds with smaller mean pore sizes (94, 130??m). Taken together, these findings demonstrate the importance of scaffold micro-architecture in the development of advanced tissue engineering strategies for articular cartilage defect repair.
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One step preparation and electrochemical analysis of IQS, a cell-cell communication signal in the nosocomial pathogen Pseudomonas aeruginosa.
Bioorg. Med. Chem. Lett.
PUBLISHED: 08-14-2014
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Pseudomonas aeruginosa uses a hierarchical cell-cell communication system consisting of a number of regulatory elements to coordinate the expression of bacterial virulence genes. Sensitive detection of quorum sensing (QS) molecules has the potential for early identification of P. aeruginosa facilitating early medical intervention. A recently isolated cell-cell communication molecule, a thiazole termed IQS, can bypass the las QS system of P. aeruginosa under times of stress, activating a subset of QS-controlled genes. This compound offers a new target for pathogen detection and has been prepared in a one step protocol. A simple electrochemical strategy was employed for its sensitive detection using boron-doped diamond and glassy carbon electrodes by cyclic voltammetry and amperometry.
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Combinatorial Gene Therapy Accelerates Bone Regeneration: Non-Viral Dual Delivery of VEGF and BMP2 in a Collagen-Nanohydroxyapatite Scaffold.
Adv Healthc Mater
PUBLISHED: 08-13-2014
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Vascularization and bone repair are accelerated by a series of gene-activated scaffolds delivering both an angiogenic and an osteogenic gene. Stem cell-mediated osteogenesis in vitro, in addition to increased vascularization and bone repair by host cells in vivo, is enhanced using all systems while the use of the nanohydroxyapatite vector to deliver both genes markedly enhances bone healing.
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Bile acids repress hypoxia-inducible factor 1 signaling and modulate the airway immune response.
Infect. Immun.
PUBLISHED: 06-09-2014
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Gastroesophageal reflux (GER) frequently occurs in patients with respiratory disease and is particularly prevalent in patients with cystic fibrosis. GER is a condition in which the duodenogastric contents of the stomach leak into the esophagus, in many cases resulting in aspiration into the respiratory tract. As such, the presence of GER-derived bile acids (BAs) has been confirmed in the bronchoalveolar lavage fluid and sputum of affected patients. We have recently shown that bile causes cystic fibrosis-associated bacterial pathogens to adopt a chronic lifestyle and may constitute a major host trigger underlying respiratory infection. The current study shows that BAs elicit a specific response in humans in which they repress hypoxia-inducible factor 1? (HIF-1?) protein, an emerging master regulator in response to infection and inflammation. HIF-1? repression was shown to occur through the 26S proteasome machinery via the prolyl hydroxylase domain (PHD) pathway. Further analysis of the downstream inflammatory response showed that HIF-1? repression by BAs can significantly modulate the immune response of airway epithelial cells, correlating with a decrease in interleukin-8 (IL-8) production, while IL-6 production was strongly increased. Importantly, the effects of BAs on cytokine production can also be more dominant than the bacterium-mediated effects. However, the effect of BAs on cytokine levels cannot be fully explained by their ability to repress HIF-1?, which is not surprising, given the complexity of the immune regulatory network. The suppression of HIF-1 signaling by bile acids may have a significant influence on the progression and outcome of respiratory disease, and the molecular mechanism underpinning this response warrants further investigation.
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Arousal from Sleep Does Not Lead to Reduced Dilator Muscle Activity or Elevated Upper Airway Resistance on Return to Sleep in Healthy Individuals.
Sleep
PUBLISHED: 05-23-2014
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To compare changes in end-tidal CO2, genioglossus muscle activity and upper airway resistance following tone-induced arousal and the return to sleep in healthy individuals with small and large ventilatory responses to arousal.
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A new regulator of pathogenicity (bvlR) is required for full virulence and tight microcolony formation in Pseudomonas aeruginosa.
Microbiology (Reading, Engl.)
PUBLISHED: 05-14-2014
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LysR-type transcriptional regulators (LTTRs) are the most common family of transcriptional regulators found in the opportunistic pathogen Pseudomonas aeruginosa. They are known to regulate a wide variety of virulence determinants and have emerged recently as positive global regulators of pathogenicity in a broad spectrum of important bacterial pathogens. However, in spite of their key role in modulating expression of key virulence determinants underpinning pathogenic traits associated with the process of infection, surprisingly few are found to be transcriptionally altered by contact with host cells. BvlR (PA14_26880) an LTTR of previously unknown function, has been shown to be induced in response to host cell contact, and was therefore investigated for its potential role in virulence. BvlR expression was found to play a pivotal role in the regulation of acute virulence determinants such as type III secretion system and exotoxin A production. BvlR also played a key role in P. aeruginosa pathogenicity within the Caenorhabditis elegans acute model of infection. Loss of BvlR led to an inability to form tight microcolonies, a key step in biofilm formation in the cystic fibrosis lung, although surface attachment was increased. Unusually for LTTRs, BvlR was shown to exert its influence through the transcriptional repression of many genes, including the virulence-associated cupA and alg genes. This highlights the importance of BvlR as a new virulence regulator in P. aeruginosa with a central role in modulating key events in the pathogen-host interactome.
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Inhibition of co-colonizing cystic fibrosis-associated pathogens by Pseudomonas aeruginosa and Burkholderia multivorans.
Microbiology (Reading, Engl.)
PUBLISHED: 04-30-2014
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Cystic fibrosis (CF) is a recessive genetic disease characterized by chronic respiratory infections and inflammation causing permanent lung damage. Recurrent infections are caused by Gram-negative antibiotic-resistant bacterial pathogens such as Pseudomonas aeruginosa, Burkholderia cepacia complex (Bcc) and the emerging pathogen genus Pandoraea. In this study, the interactions between co-colonizing CF pathogens were investigated. Both Pandoraea and Bcc elicited potent pro-inflammatory responses that were significantly greater than Ps. aeruginosa. The original aim was to examine whether combinations of pro-inflammatory pathogens would further exacerbate inflammation. In contrast, when these pathogens were colonized in the presence of Ps. aeruginosa the pro-inflammatory response was significantly decreased. Real-time PCR quantification of bacterial DNA from mixed cultures indicated that Ps. aeruginosa significantly inhibited the growth of Burkholderia multivorans, Burkholderia cenocepacia, Pandoraea pulmonicola and Pandoraea apista, which may be a factor in its dominance as a colonizer of CF patients. Ps. aeruginosa cell-free supernatant also suppressed growth of these pathogens, indicating that inhibition was innate rather than a response to the presence of a competitor. Screening of a Ps. aeruginosa mutant library highlighted a role for quorum sensing and pyoverdine biosynthesis genes in the inhibition of B. cenocepacia. Pyoverdine was confirmed to contribute to the inhibition of B. cenocepacia strain J2315. B. multivorans was the only species that could significantly inhibit Ps. aeruginosa growth. B. multivorans also inhibited B. cenocepacia and Pa. apista. In conclusion, both Ps. aeruginosa and B. multivorans are capable of suppressing growth and virulence of co-colonizing CF pathogens.
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Night-to-night repeatability of supine-related obstructive sleep apnea.
Ann Am Thorac Soc
PUBLISHED: 04-12-2014
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Patients with obstructive sleep apnea (OSA) experience respiratory events with greater frequency and severity while in the supine sleeping position. Postural modification devices (PMDs) prevent supine sleep, although there is a paucity of guidance to help clinicians decide when to use PMDs for their patients. In order for PMDs to treat OSA effectively, patients must experience respiratory events in the supine sleeping position consistently from night to night and must have a low nonsupine apnea and hypopnea index (AHINS).
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Emerging strategies and integrated systems microbiology technologies for biodiscovery of marine bioactive compounds.
Mar Drugs
PUBLISHED: 04-08-2014
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Marine microorganisms continue to be a source of structurally and biologically novel compounds with potential use in the biotechnology industry. The unique physiochemical properties of the marine environment (such as pH, pressure, temperature, osmolarity) and uncommon functional groups (such as isonitrile, dichloroimine, isocyanate, and halogenated functional groups) are frequently found in marine metabolites. These facts have resulted in the production of bioactive substances with different properties than those found in terrestrial habitats. In fact, the marine environment contains a relatively untapped reservoir of bioactivity. Recent advances in genomics, metagenomics, proteomics, combinatorial biosynthesis, synthetic biology, screening methods, expression systems, bioinformatics, and the ever increasing availability of sequenced genomes provides us with more opportunities than ever in the discovery of novel bioactive compounds and biocatalysts. The combination of these advanced techniques with traditional techniques, together with the use of dereplication strategies to eliminate known compounds, provides a powerful tool in the discovery of novel marine bioactive compounds. This review outlines and discusses the emerging strategies for the biodiscovery of these bioactive compounds.
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Metabolomic profiling and genomic study of a marine sponge-associated Streptomyces sp.
Mar Drugs
PUBLISHED: 03-25-2014
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Metabolomics and genomics are two complementary platforms for analyzing an organism as they provide information on the phenotype and genotype, respectively. These two techniques were applied in the dereplication and identification of bioactive compounds from a Streptomyces sp. (SM8) isolated from the sponge Haliclona simulans from Irish waters. Streptomyces strain SM8 extracts showed antibacterial and antifungal activity. NMR analysis of the active fractions proved that hydroxylated saturated fatty acids were the major components present in the antibacterial fractions. Antimycin compounds were initially putatively identified in the antifungal fractions using LC-Orbitrap. Their presence was later confirmed by comparison to a standard. Genomic analysis of Streptomyces sp. SM8 revealed the presence of multiple secondary metabolism gene clusters, including a gene cluster for the biosynthesis of the antifungal antimycin family of compounds. The antimycin gene cluster of Streptomyces sp. SM8 was inactivated by disruption of the antimycin biosynthesis gene antC. Extracts from this mutant strain showed loss of antimycin production and significantly less antifungal activity than the wild-type strain. Three butenolides, 4,10-dihydroxy-10-methyl-dodec-2-en-1,4-olide (1), 4,11-dihydroxy-10-methyl-dodec-2-en-1,4-olide (2), and 4-hydroxy-10-methyl-11-oxo-dodec-2-en-1,4-olide (3) that had previously been reported from marine Streptomyces species were also isolated from SM8. Comparison of the extracts of Streptomyces strain SM8 and its host sponge, H. simulans, using LC-Orbitrap revealed the presence of metabolites common to both extracts, providing direct evidence linking sponge metabolites to a specific microbial symbiont.
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Thermally triggered release of a pro-osteogenic peptide from a functionalized collagen-based scaffold using thermosensitive liposomes.
J Control Release
PUBLISHED: 03-04-2014
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Collagen is one of the most attractive materials for the development of matrices for tissue engineering, due to its excellent biocompatibility and non-toxic bioresorption. The present work describes a collagen-based externally controlled drug-eluting scaffold which consists of drug encapsulated thermoresponsive liposomes covalently attached to the surface of a functionalized collagen-based scaffold. The model drug used in this work was PTHrP 107-111, a pentapeptide with pro-osteogenic and antiosteoclastic activity. An osteoconductive collagen-hydroxyapatite scaffold, designed specifically for bone repair, was used as a model scaffold. The results demonstrate that it is possible to modify the kinetics of release of the drug from the scaffold with the application of an external thermal stimulus (42°C, 20min). In vitro studies carried out with pre-osteoblastic MC3T3-E1 cells demonstrated that neither the attachment of liposomes to the surface of the scaffolds nor the hyperthermic pulse negatively affected the ability of cells to attach and proliferate on the scaffolds. Importantly, the on-demand release of PTHrP 107-111 had a pro-osteogenic effect, as shown by the enhancement of alkaline phosphatase activity, an early osteogenic marker, which correlated with increased expression of the osteogenic genes osteopontin and osteocalcin. In conclusion, the scaffold-based release system developed in this study has immense potential for tuning the delivery of a diverse range of drugs which can be applied for the regeneration of a variety of tissue types.
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Comparison of biomaterial delivery vehicles for improving acute retention of stem cells in the infarcted heart.
Biomaterials
PUBLISHED: 02-28-2014
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Cell delivery to the infarcted heart has emerged as a promising therapy, but is limited by very low acute retention and engraftment of cells. The objective of this study was to compare a panel of biomaterials to evaluate if acute retention can be improved with a biomaterial carrier. Cells were quantified post-implantation in a rat myocardial infarct model in five groups (n = 7-8); saline injection (current clinical standard), two injectable hydrogels (alginate, chitosan/?-glycerophosphate (chitosan/ß-GP)) and two epicardial patches (alginate, collagen). Human mesenchymal stem cells (hMSCs) were delivered to the infarct border zone with each biomaterial. At 24 h, retained cells were quantified by fluorescence. All biomaterials produced superior fluorescence to saline control, with approximately 8- and 14-fold increases with alginate and chitosan/?-GP injectables, and 47 and 59-fold increases achieved with collagen and alginate patches, respectively. Immunohistochemical analysis qualitatively confirmed these findings. All four biomaterials retained 50-60% of cells that were present immediately following transplantation, compared to 10% for the saline control. In conclusion, all four biomaterials were demonstrated to more efficiently deliver and retain cells when compared to a saline control. Biomaterial-based delivery approaches show promise for future development of efficient in vivo delivery techniques.
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An experimental investigation of the effect of mechanical and biochemical stimuli on cell migration within a decellularized vascular construct.
Ann Biomed Eng
PUBLISHED: 02-23-2014
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The goal of this study was to promote rapid repopulation of the medial layer of decellularized tissues for use as vascular grafts. We utilized a combined approach of biochemical and mechanical stimuli to enhance repopulation of decellularized porcine arterial tissue. Chitosan ?-glycerophosphate loaded with hepatocyte growth factor (HGF) was injected into a channel in the artery wall while rat mesenchymal stem cells (rMSCs) were injected in two channels located 120° to this channel. In a second group rMSCs were injected into channels located at intervals of 120°. Both groups were subjected to 7 days mechanical stimuli in comparison to non-dynamically conditioned static controls. The combined effect of the biochemical and mechanical stimuli demonstrated that the repopulation zone was significantly enhanced, maximum migration achieved was 1.8 times more than that of the static HGF cultured control and 10 times higher than the average migration for statically cultured scaffolds without biochemical stimulus. Human umbilical vein endothelial cells were also successfully adhered to the scaffold and dynamically cultured. The response of medially injected cells to the biomechanically and biochemically altered environment demonstrated that enhanced circumferential scaffold repopulation could be achieved.
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Recapitulating endochondral ossification: a promising route to in vivo bone regeneration.
J Tissue Eng Regen Med
PUBLISHED: 02-14-2014
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Despite its natural healing potential, bone is unable to regenerate sufficient tissue within critical-sized defects, resulting in a non-union of bone ends. As a consequence, interventions are required to replace missing, damaged or diseased bone. Bone grafts have been widely employed for the repair of such critical-sized defects. However, the well-documented drawbacks associated with autografts, allografts and xenografts have motivated the development of alternative treatment options. Traditional tissue engineering strategies have typically attempted to direct in vitro bone-like matrix formation within scaffolds prior to implantation into bone defects, mimicking the embryological process of intramembranous ossification (IMO). Tissue-engineered constructs developed using this approach often fail once implanted, due to poor perfusion, leading to avascular necrosis and core degradation. As a result of such drawbacks, an alternative tissue engineering strategy, based on endochondral ossification (ECO), has begun to emerge, involving the use of in vitro tissue-engineered cartilage as a transient biomimetic template to facilitate bone formation within large defects. This is driven by the hypothesis that hypertrophic chondrocytes can secrete angiogenic and osteogenic factors, which play pivotal roles in both the vascularization of constructs in vivo and the deposition of a mineralized extracellular matrix, with resulting bone deposition. In this context, this review focuses on current strategies taken to recapitulate ECO, using a range of distinct cells, biomaterials and biochemical stimuli, in order to facilitate in vivo bone formation. Copyright © 2014 John Wiley & Sons, Ltd.
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Hyperthermia-induced drug delivery from thermosensitive liposomes encapsulated in an injectable hydrogel for local chemotherapy.
Adv Healthc Mater
PUBLISHED: 01-16-2014
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A novel drug delivery system, enabling an in situ, thermally triggered drug release is described, consisting of an injectable thermoresponsive chitosan hydrogel containing doxorubicin-loaded thermosensitive liposomes. The design, fabrication, characterization, and an assessment of in vitro bioactivity of this formulation is detailed. Combining on-demand drug delivery with in situ gelation results in a promising candidate for local chemotherapy.
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A collagen-hydroxyapatite scaffold allows for binding and co-delivery of recombinant bone morphogenetic proteins and bisphosphonates.
Acta Biomater
PUBLISHED: 01-14-2014
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An emerging paradigm in orthopedics is that a bone-healing outcome is the product of the anabolic (bone-forming) and catabolic (bone-resorbing) outcomes. Recently, surgical and tissue engineering strategies have emerged that combine recombinant human bone morphogenetic proteins (rhBMPs) and bisphosphonates (BPs) in order to maximize anabolism and minimize catabolism. Collagen-based scaffolds that are the current surgical standard can bind rhBMPs, but not BPs. We hypothesized that a biomimetic collagen-hydroxyapatite (CHA) scaffold would bind both agents and produce superior in vivo outcomes. Consistent with this concept, in vitro elution studies utilizing rhBMP-2 ELISA assays and scintillation counting of (14)C-radiolabeled zoledronic acid (ZA) confirmed delayed release of both agents from the CHA scaffold. Next, scaffolds were tested for their capacity to form ectopic bone after surgical implantation into the rat hind limb. Using CHA, a significant 6-fold increase in bone volume was seen in rhBMP-2/ZA groups compared to rhBMP-2 alone, confirming the ability of ZA to enhance rhBMP-2 bone formation. CHA scaffolds were found to be capable of generating mineralized tissue in the absence of rhBMP-2. This study has implications for future clinical treatments of critical bone defects. It demonstrates the relative advantages of co-delivering anabolic and anti-catabolic agents using a multicomponent scaffold system.
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Controlled release of transforming growth factor-?3 from cartilage-extra-cellular-matrix-derived scaffolds to promote chondrogenesis of human-joint-tissue-derived stem cells.
Acta Biomater
PUBLISHED: 01-07-2014
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The objective of this study was to develop a scaffold derived from cartilaginous extracellular matrix (ECM) that could be used as a growth factor delivery system to promote chondrogenesis of stem cells. Dehydrothermal crosslinked scaffolds were fabricated using a slurry of homogenized porcine articular cartilage, which was then seeded with human infrapatellar-fat-pad-derived stem cells (FPSCs). It was found that these ECM-derived scaffolds promoted superior chondrogenesis of FPSCs when the constructs were additionally stimulated with transforming growth factor (TGF)-?3. Cell-mediated contraction of the scaffold was observed, which could be limited by the additional use of 1-ethyl-3-3dimethyl aminopropyl carbodiimide (EDAC) crosslinking without suppressing cartilage-specific matrix accumulation within the construct. To further validate the utility of the ECM-derived scaffold, we next compared its chondro-permissive properties to a biomimetic collagen-hyaluronic acid (HA) scaffold optimized for cartilage tissue engineering (TE) applications. The cartilage-ECM-derived scaffold supported at least comparable chondrogenesis to the collagen-HA scaffold, underwent less contraction and retained a greater proportion of synthesized sulfated glycosaminoglycans. Having developed a promising scaffold for TE, with superior chondrogenesis observed in the presence of exogenously supplied TGF-?3, the final phase of the study explored whether this scaffold could be used as a TGF-?3 delivery system to promote chondrogenesis of FPSCs. It was found that the majority of TGF-?3 that was loaded onto the scaffold was released in a controlled manner over the first 10days of culture, with comparable long-term chondrogenesis observed in these TGF-?3-loaded constructs compared to scaffolds where the TGF-?3 was continuously added to the media. The results of this study support the use of cartilage-ECM-derived scaffolds as a growth factor delivery system for use in articular cartilage regeneration.
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Novel microhydroxyapatite particles in a collagen scaffold: a bioactive bone void filler?
Clin. Orthop. Relat. Res.
PUBLISHED: 01-03-2014
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Treatment of segmental bone loss remains a major challenge in orthopaedic surgery. Traditional techniques (eg, autograft) and newer techniques (eg, recombinant human bone morphogenetic protein-2 [rhBMP-2]) have well-established performance limitations and safety concerns respectively. Consequently there is an unmet need for osteoinductive bone graft substitutes that may eliminate or reduce the use of rhBMP-2.
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A biomimetic multi-layered collagen-based scaffold for osteochondral repair.
Acta Biomater
PUBLISHED: 01-02-2014
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Cartilage and osteochondral defects pose a significant challenge in orthopedics. Tissue engineering has shown promise as a potential method for the treatment of such defects; however, a long-lasting repair strategy has yet to be realized. This study focuses on the development of a layered construct for osteochondral repair, fabricated through a novel "iterative layering" freeze-drying technique. The process involved repeated steps of layer addition followed by freeze-drying, enabling control over material composition, pore size and substrate stiffness in each region of the construct, while also achieving a seamlessly integrated layer structure. The novel construct developed mimics the inherent gradient structure of healthy osteochondral tissue: a bone layer composed of type I collagen and hydroxyapatite (HA), an intermediate layer composed of type I collagen, type II collagen and HA and a cartilaginous region composed of type I collagen, type II collagen and hyaluronic acid. The material properties were designed to provide the biological cues required to encourage infiltration of host cells from the bone marrow while the biomechanical properties were designed to provide an environment optimized to promote differentiation of these cells towards the required lineage in each region. This novel osteochondral graft was shown to have a seamlessly integrated layer structure, high levels of porosity (>97%), a homogeneous pore structure and a high degree of pore interconnectivity. Moreover, homogeneous cellular distribution throughout the entire construct was evident following in vitro culture, demonstrating the potential of this multi-layered scaffold as an advanced strategy for osteochondral defect repair.
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Enamel Matrix Derivative has No Effect on the Chondrogenic Differentiation of Mesenchymal Stem Cells.
Front Bioeng Biotechnol
PUBLISHED: 01-01-2014
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Treatment of large bone defects due to trauma, tumor resection, or congenital abnormalities is challenging. Bone tissue engineering using mesenchymal stem cells (MSCs) represents a promising treatment option. However, the quantity and quality of engineered bone tissue are not sufficient to fill large bone defects. The aim of this study was to determine if the addition of enamel matrix derivative (EMD) improves in vitro chondrogenic priming of MSCs to ultimately improve in vivo MSC mediated endochondral bone formation.
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The impact of simvastatin on pulmonary effectors of Pseudomonas aeruginosa infection.
PLoS ONE
PUBLISHED: 01-01-2014
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The statin family of cholesterol-lowering drugs is known to have pleiotropic properties which include anti-inflammatory and immunomodulatory effects. Statins exert their pleiotropic effects by altering expression of human immune regulators including pro-inflammatory cytokines. Previously we found that statins modulate virulence phenotypes of the human pathogen Pseudomonas aeruginosa, and sought to investigate if simvastatin could alter the host response to this organism in lung epithelial cells. Simvastatin increased the expression of the P. aeruginosa target genes KLF2, KLF6, IL-8 and CCL20. Furthermore, both simvastatin and P. aeruginosa induced alternative splicing of KLF6. The novel effect of simvastatin on wtKLF6 expression was found to be responsible for induction of the KLF6 regulated genes CCL20 and iNOS. Simvastatin also increased the adhesion of P. aeruginosa to host cells, without altering invasion or cytotoxicity. This study demonstrated that simvastatin had several novel effects on the pulmonary cellular immune response.
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The SPI-1-like Type III secretion system: more roles than you think.
Front Plant Sci
PUBLISHED: 01-01-2014
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The type III secretion system (T3SS) is a protein delivery system which is involved in a wide spectrum of interactions, from mutualism to pathogenesis, between Gram negative bacteria and various eukaryotes, including plants, fungi, protozoa and mammals. Various phylogenetic families of the T3SS have been described, including the Salmonella Pathogenicity Island 1 family (SPI-1). The SPI-1 T3SS was initially associated with the virulence of enteric pathogens, but is actually found in a diverse array of bacterial species, where it can play roles in processes as different as symbiotic interactions with insects and colonization of plants. We review the multiple roles of the SPI-1 T3SS and discuss both how these discoveries are changing our perception of the SPI-1 family and what impacts this has on our understanding of the specialization of the T3SS in general.
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Aquimarina amphilecti sp. nov., isolated from the sponge Amphilectus fucorum.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 10-09-2013
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A Gram staining negative, rod-shaped orange-coloured, catalase and oxidase positive, non-motile bacterium designated as 92VT was isolated from the marine sponge, Amphilectus fucorum, collected from Lough Hyne, Co. Cork, Ireland. 16S rRNA gene sequence analysis revealed that strain 92VT clustered with members of the family Flavobacteriaceae, the closest member being Aquimarina latercula NCIMB 1399T, with a gene sequence similarity of 97.5%. Strain 92VT requires seawater for growth with optimal growth occurring at 25°C, pH 6-7 and 3 % (w/v) NaCl. MK-6 is the sole respiratory quinone present and the major fatty acids are iso-C17:0 3-OH, iso-C15:0, iso-C17:1 ?9c and iso-C15:0 3-OH. The DNA G+C content is 36.1 Mol%. Combined phenotypic differences and phylogenetic analysis indicate that strain 92VT represents a novel species of the genus Aquimarina, for which the name Aquimarina amphilecti sp. nov is proposed with strain 92VT as the type strain (=NCIMB 14723T = DSM 25232 T).
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Cell-scaffold interactions in the bone tissue engineering triad.
Eur Cell Mater
PUBLISHED: 09-21-2013
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Bone tissue engineering has emerged as one of the leading fields in tissue engineering and regenerative medicine. The success of bone tissue engineering relies on understanding the interplay between progenitor cells, regulatory signals, and the biomaterials/scaffolds used to deliver them--otherwise known as the tissue engineering triad. This review will discuss the roles of these fundamental components with a specific focus on the interaction between cell behaviour and scaffold structural properties. In terms of scaffold architecture, recent work has shown that pore size can affect both cell attachment and cellular invasion. Moreover, different materials can exert different biomechanical forces, which can profoundly affect cellular differentiation and migration in a cell type specific manner. Understanding these interactions will be critical for enhancing the progress of bone tissue engineering towards clinical applications.
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Specific sleepiness symptoms are indicators of performance impairment during sleep deprivation.
Accid Anal Prev
PUBLISHED: 07-24-2013
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Drivers are not always aware that they are becoming impaired as a result of sleepiness. Using specific symptoms of sleepiness might assist with recognition of drowsiness related impairment and help drivers judge whether they are safe to drive a vehicle, however this has not been evaluated. In this study, 20 healthy volunteer professional drivers completed two randomized sessions in the laboratory - one under 24h of acute sleep deprivation, and one with alcohol. The Psychomotor Vigilance Task (PVT) and a 30min simulated driving task (AusEdTM) were performed every 3-4h in the sleep deprivation session, and at a BAC of 0.00% and 0.05% in the alcohol session, while electroencephalography (EEG) and eye movements were recorded. After each test session, drivers completed the Karolinska Sleepiness Scale (KSS) and the Sleepiness Symptoms Questionnaire (SSQ), which includes eight specific sleepiness and driving performance symptoms. A second baseline session was completed on a separate day by the professional drivers and in an additional 20 non-professional drivers for test-retest reliability. There was moderate test-retest agreement on the SSQ (r=0.59). Significant correlations were identified between individual sleepiness symptoms and the KSS score (r values 0.50-0.74, p<0.01 for all symptoms). The frequency of all SSQ items increased during sleep deprivation (?(2) values of 28.4-80.2, p<0.01 for all symptoms) and symptoms were related to increased subjective sleepiness and performance deterioration. The symptoms "struggling to keep your eyes open", "difficulty maintaining correct speed", "reactions were slow" and "head dropping down" were most closely related to increased alpha and theta activity on EEG (r values 0.49-0.59, p<0.001) and "nodding off to sleep" and "struggling to keep your eyes open" were related to slow eye movements (r values 0.67 and 0.64, p<0.001). Symptoms related to visual disturbance and impaired driving performance were most accurate at detecting severely impaired driving performance (AUC on ROC curve of 0.86-0.91 for detecting change in lateral lane position greater than the change at a BAC of 0.05%). Individual sleepiness symptoms are related to impairment during acute sleep deprivation and might be able to assist drivers in recognizing their own sleepiness and ability to drive safely.
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Phosphoinositide 3-kinases as accelerators and brakes of autophagy.
FEBS J.
PUBLISHED: 07-01-2013
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Degradation of cytoplasmic material by autophagy plays a key role in protein homeostasis and metabolic control, as well as in the removal of intracellular protein aggregates, pathogens and damaged organelles. The concept of up- or down-regulating this pathway pharmacologically in neurodegenerative diseases, infections, inflammation and cancer is therefore attractive. Among the key pharmacological targets in regulation of autophagy are the phosphoinositide 3-kinases (PI3Ks), which mediate the phosphorylation of phosphatidylinositol (PtdIns) or PtdIns 4,5-bisphosphate in the 3-position of the (phospho)inositol headgroup. The catalytic products, PtdIns 3-phosphate (PtdIns3P) and PtdIns 3,4,5-trisphosphate [PtdIns(3,4,5)P3 ], respectively, have opposing roles in autophagy. PtdIns3P, the product of class II and III PI3Ks, mediates the recruitment of specific autophagic effectors to the sites of origin of autophagic membranes and thereby plays an essential role in canonical autophagy. By contrast, PtdIns(3,4,5)P3 , the product of class I PI3Ks, triggers the target of rapamycin signalling pathway, which inhibits autophagy. In this review, we discuss the functions of class I, II and III PI3Ks in autophagy and describe the protein effectors of PtdIns3P and PtdIns(3,4,5)P3 that promote or inhibit autophagy, respectively. We also provide examples of how PI3K-mediated control of autophagy is relevant to an understanding of tumour suppression and progression.
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Two-tiered control of epithelial growth and autophagy by the insulin receptor and the ret-like receptor, stitcher.
PLoS Biol.
PUBLISHED: 07-01-2013
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Body size in Drosophila larvae, like in other animals, is controlled by nutrition. Nutrient restriction leads to catabolic responses in the majority of tissues, but the Drosophila mitotic imaginal discs continue growing. The nature of these differential control mechanisms that spare distinct tissues from starvation are poorly understood. Here, we reveal that the Ret-like receptor tyrosine kinase (RTK), Stitcher (Stit), is required for cell growth and proliferation through the PI3K-I/TORC1 pathway in the Drosophila wing disc. Both Stit and insulin receptor (InR) signaling activate PI3K-I and drive cellular proliferation and tissue growth. However, whereas optimal growth requires signaling from both InR and Stit, catabolic changes manifested by autophagy only occur when both signaling pathways are compromised. The combined activities of Stit and InR in ectodermal epithelial tissues provide an RTK-mediated, two-tiered reaction threshold to varying nutritional conditions that promote epithelial organ growth even at low levels of InR signaling.
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Auto-titrating continuous positive airway pressure treatment for obstructive sleep apnoea after acute quadriplegia (COSAQ): study protocol for a randomized controlled trial.
Trials
PUBLISHED: 06-04-2013
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Quadriplegia is a severe, catastrophic injury that predominantly affects people early in life, resulting in lifelong physical disability. Obstructive sleep apnoea is a direct consequence of quadriplegia and is associated with neurocognitive deficits, sleepiness and reduced quality of life. The usual treatment for sleep apnoea is nasal continuous positive airway pressure (CPAP); however, this is poorly tolerated in quadriplegia. To encourage patients to use this therapy, we have to demonstrate that the benefits outweigh the inconvenience. We therefore propose a prospective, multinational randomized controlled trial of three months of CPAP for obstructive sleep apnoea after acute quadriplegia.
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Hypoglossal nerve stimulation improves obstructive sleep apnoea: 12-month outcomes.
J Sleep Res
PUBLISHED: 05-23-2013
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Reduced upper airway muscle activity during sleep is a key contributor to obstructive sleep apnoea pathogenesis. Hypoglossal nerve stimulation activates upper airway dilator muscles, including the genioglossus, and has the potential to reduce obstructive sleep apnoea severity. The objective of this study was to examine the safety, feasibility and efficacy of a novel hypoglossal nerve stimulation system (HGNS(®) ; Apnex Medical, St Paul, MN, USA) in treating obstructive sleep apnoea at 12 months following implantation. Thirty-one subjects (35% female, age 52.4 ± 9.4 years) with moderate to severe obstructive sleep apnoea and unable to tolerate positive airway pressure underwent surgical implantation and activation of the hypoglossal nerve stimulation system in a prospective single-arm interventional trial. Primary outcomes were changes in obstructive sleep apnoea severity (apnoea-hypopnoea index, from in-laboratory polysomnogram) and sleep-related quality of life [Functional Outcomes of Sleep Questionnaire (FOSQ)]. Hypoglossal nerve stimulation was used on 86 ± 16% of nights for 5.4 ± 1.4 h per night. There was a significant improvement (P < 0.001) from baseline to 12 months in apnoea-hypopnoea index (45.4 ± 17.5 to 25.3 ± 20.6 events h(-1) ) and Functional Outcomes of Sleep Questionnaire score (14.2 ± 2.0 to 17.0 ± 2.4), as well as other polysomnogram and symptom measures. Outcomes were stable compared with 6 months following implantation. Three serious device-related adverse events occurred: an infection requiring device removal; and two stimulation lead cuff dislodgements requiring replacement. There were no significant adverse events with onset later than 6 months following implantation. Hypoglossal nerve stimulation demonstrated favourable safety, feasibility and efficacy.
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Can we predict sleep-disordered breathing in pregnancy? The clinical utility of symptoms.
J Sleep Res
PUBLISHED: 04-28-2013
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Sleep-disordered breathing (SDB) is reported commonly during pregnancy and is associated with an increased risk of adverse maternal and fetal outcomes, but the majority of these data are based upon self-report measures not validated for pregnancy. This study examined the predictive value of screening questionnaires for SDB administered at two time-points in pregnancy, and attempted to develop an optimized predictive model for detecting SDB in pregnancy. A total of 380 women were recruited from an antenatal clinic in the second trimester of pregnancy. All participants completed the Berlin Questionnaire and the Multivariable Apnea Risk Index (MAP Index) at recruitment, with a subset of 43 women repeating the questionnaires at the time of polysomnography at 37 weeks gestation. Fifteen of 43 (35%) women were confirmed to have a respiratory disturbance index (RDI) > 5 h(-1) . Prediction of an RDI > 5 h(-1) was most accurate during the second trimester for both the Berlin Questionnaire (sensitivity 0.93, specificity 0.50, positive predictive value 0.50 and negative predictive value 0.93), and the MAP Index [area under the receiver operating characteristic (ROC) curve of 0.768]. A stepwise selection model identified snoring volume, a body mass index (BMI)?32 kg m(-2) and tiredness upon awakening as the strongest independent predictors of SDB during pregnancy; this model had an area under the ROC curve of 0.952. We conclude that existing clinical prediction models for SDB perform inadequately as a screening tool in pregnancy. The development of a highly predictive model from our data shows promise for a quick and easy screening tool to be validated for future use in pregnancy.
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Subtilomycin: a new lantibiotic from Bacillus subtilis strain MMA7 isolated from the marine sponge Haliclona simulans.
Mar Drugs
PUBLISHED: 04-25-2013
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Bacteriocins are attracting increased attention as an alternative to classic antibiotics in the fight against infectious disease and multidrug resistant pathogens. Bacillus subtilis strain MMA7 isolated from the marine sponge Haliclona simulans displays a broad spectrum antimicrobial activity, which includes Gram-positive and Gram-negative pathogens, as well as several pathogenic Candida species. This activity is in part associated with a newly identified lantibiotic, herein named as subtilomycin. The proposed biosynthetic cluster is composed of six genes, including protein-coding genes for LanB-like dehydratase and LanC-like cyclase modification enzymes, characteristic of the class I lantibiotics. The subtilomycin biosynthetic cluster in B. subtilis strain MMA7 is found in place of the sporulation killing factor (skf) operon, reported in many B. subtilis isolates and involved in a bacterial cannibalistic behaviour intended to delay sporulation. The presence of the subtilomycin biosynthetic cluster appears to be widespread amongst B. subtilis strains isolated from different shallow and deep water marine sponges. Subtilomycin possesses several desirable industrial and pharmaceutical physicochemical properties, including activity over a wide pH range, thermal resistance and water solubility. Additionally, the production of the lantibiotic subtilomycin could be a desirable property should B. subtilis strain MMA7 be employed as a probiotic in aquaculture applications.
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Meeting report: 1st international functional metagenomics workshop may 7-8, 2012, st. Jacobs, ontario, Canada.
Stand Genomic Sci
PUBLISHED: 04-15-2013
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This report summarizes the events of the 1(st) International Functional Metagenomics Workshop. The workshop was held on May 7 and 8, 2012, in St. Jacobs, Ontario, Canada and was focused on building an international functional metagenomics community, exploring strategic research areas, and identifying opportunities for future collaboration and funding. The workshop was initiated by researchers at the University of Waterloo with support from the Ontario Genomics Institute (OGI), Natural Sciences and Engineering Research Council of Canada (NSERC) and the University of Waterloo.
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Characterization of mineral phosphate solubilization traits from a barley rhizosphere soil functional metagenome.
Microbiologyopen
PUBLISHED: 04-15-2013
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Mineral phosphate solubilization (MPS) microorganisms are important for their provision of orthophosphate anions for plant growth promotion activity in soil. In this study, we applied a functional metagenomic approach to identify this trait directly from the microbiome in barley rhizosphere soil that had not received P fertilizer over a 15-year period. A fosmid system was used to clone the metagenome of which 18,000 clones (~666 Mb of DNA) was screened for MPS. Functional assays and High Performance Liquid Chromatography analysis recognized gluconic acid production and MPS activity in the range 24.8-77.1 mmol/L and 27.6-38.16 ?g/mL, respectively, when screened in an Escherichia coli host (at frequency of one MPS-positive clone hit per 114 Mb DNA tested). The MPS clones (with average insert size of ~37 kb) were analysed by 454 Roche sequencing and annotated. A number of genes/operons with homology to Phosphorous (P) uptake, regulatory and solubilization mechanisms were identified, linking the MPS function to the uncultivated microbiome present in barley rhizosphere soil.
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Chitosan for gene delivery and orthopedic tissue engineering applications.
Molecules
PUBLISHED: 04-01-2013
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Gene therapy involves the introduction of foreign genetic material into cells in order exert a therapeutic effect. The application of gene therapy to the field of orthopaedic tissue engineering is extremely promising as the controlled release of therapeutic proteins such as bone morphogenetic proteins have been shown to stimulate bone repair. However, there are a number of drawbacks associated with viral and synthetic non-viral gene delivery approaches. One natural polymer which has generated interest as a gene delivery vector is chitosan. Chitosan is biodegradable, biocompatible and non-toxic. Much of the appeal of chitosan is due to the presence of primary amine groups in its repeating units which become protonated in acidic conditions. This property makes it a promising candidate for non-viral gene delivery. Chitosan-based vectors have been shown to transfect a number of cell types including human embryonic kidney cells (HEK293) and human cervical cancer cells (HeLa). Aside from its use in gene delivery, chitosan possesses a range of properties that show promise in tissue engineering applications; it is biodegradable, biocompatible, has anti-bacterial activity, and, its cationic nature allows for electrostatic interaction with glycosaminoglycans and other proteoglycans. It can be used to make nano- and microparticles, sponges, gels, membranes and porous scaffolds. Chitosan has also been shown to enhance mineral deposition during osteogenic differentiation of MSCs in vitro. The purpose of this review is to critically discuss the use of chitosan as a gene delivery vector with emphasis on its application in orthopedic tissue engineering.
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Surgical checklists: the human factor.
Patient Saf Surg
PUBLISHED: 03-29-2013
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Surgical checklists has been shown to improve patient safety and teamwork in the operating theatre. However, despite the known benefits of the use of checklists in surgery, in some cases the practical implementation has been found to be less than universal. A questionnaire methodology was used to quantitatively evaluate the attitudes of theatre staff towards a modified version of the World Health Organisation (WHO) surgical checklist with relation to: beliefs about levels of compliance and support, impact on patient safety and teamwork, and barriers to the use of the checklist.
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The bacterial secondary metabolite 2,4-diacetylphloroglucinol impairs mitochondrial function and affects calcium homeostasis in Neurospora crassa.
Fungal Genet. Biol.
PUBLISHED: 02-06-2013
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The bacterial secondary metabolite 2,4-diacetylphloroglucinol (DAPG) is of interest as an active ingredient of biological control strains of Pseudomonas fluorescens and as a potential lead pharmaceutical molecule because of its capacity to inhibit growth of diverse microbial and non-microbial cells. The mechanism by which this occurs is unknown and in this study the filamentous fungus Neurospora crassa was used as a model to investigate the effects of DAPG on a eukaryotic cell. Colony growth, conidial germination and cell fusion assays confirmed the inhibitory nature of DAPG towards N. crassa. A number of different fluorescent dyes and fluorescent protein reporters were used to assess the effects of DAPG treatment on mitochondrial and other cellular functions. DAPG treatment led to changes in mitochondrial morphology, and rapid loss of mitochondrial membrane potential. These effects are likely to be responsible for the toxicity of DAPG. It was also found that DAPG treatment caused extracellular calcium to be taken up by conidial germlings leading to a transient increase in cytosolic free Ca(2+) with a distinct concentration dependent Ca(2+) signature.
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Genome-wide investigation of cellular targets and mode of action of the antifungal bacterial metabolite 2,4-diacetylphloroglucinol in Saccharomyces cerevisiae.
FEMS Yeast Res.
PUBLISHED: 02-01-2013
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Saccharomyces cerevisiae is a proven model to investigate the effects of small molecules and drugs on fungal and eukaryotic cells. In this study, the mode of action of an antifungal metabolite, 2,4-diacetylphloroglucinol (DAPG), was determined. Applying a combination of genetic and physiological approaches, it was established that this bacterial metabolite acts as a proton ionophore and dissipates the proton gradient across the mitochondrial membrane. The uncoupling of respiration and ATP synthesis ultimately leads to growth inhibition and is the primary toxic effect of DAPG. A genome-wide screen identified 154 DAPG-tolerant mutants and showed that there are many alterations in cellular metabolism that can confer at least some degree of tolerance to this uncoupler. One mutant, ydc1, was studied in some more detail as it displayed increased tolerance to both DAPG and the uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) and appears to be unconnected to other tolerant mutant strains. Deleting YDC1 alters sphingolipid homoeostasis in the cell, and we suggest here that this may be linked to reduced drug sensitivity. Sphingolipids and their derivatives are important eukaryotic signal molecules, and the observation that altering homoeostasis may affect yeast response to metabolic uncoupling agents raises some intriguing questions for future studies.
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A non-classical LysR-type transcriptional regulator PA2206 is required for an effective oxidative stress response in Pseudomonas aeruginosa.
PLoS ONE
PUBLISHED: 01-28-2013
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LysR-type transcriptional regulators (LTTRs) are emerging as key circuit components in regulating microbial stress responses and are implicated in modulating oxidative stress in the human opportunistic pathogen Pseudomonas aeruginosa. The oxidative stress response encapsulates several strategies to overcome the deleterious effects of reactive oxygen species. However, many of the regulatory components and associated molecular mechanisms underpinning this key adaptive response remain to be characterised. Comparative analysis of publically available transcriptomic datasets led to the identification of a novel LTTR, PA2206, whose expression was altered in response to a range of host signals in addition to oxidative stress. PA2206 was found to be required for tolerance to H(2)O(2)in vitro and lethality in vivo in the Zebrafish embryo model of infection. Transcriptomic analysis in the presence of H(2)O(2) showed that PA2206 altered the expression of 58 genes, including a large repertoire of oxidative stress and iron responsive genes, independent of the master regulator of oxidative stress, OxyR. Contrary to the classic mechanism of LysR regulation, PA2206 did not autoregulate its own expression and did not influence expression of adjacent or divergently transcribed genes. The PA2214-15 operon was identified as a direct target of PA2206 with truncated promoter fragments revealing binding to the 5-ATTGCCTGGGGTTAT-3 LysR box adjacent to the predicted -35 region. PA2206 also interacted with the pvdS promoter suggesting a global dimension to the PA2206 regulon, and suggests PA2206 is an important regulatory component of P. aeruginosa adaptation during oxidative stress.
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Orchestrating osteogenic differentiation of mesenchymal stem cells--identification of placental growth factor as a mechanosensitive gene with a pro-osteogenic role.
Stem Cells
PUBLISHED: 01-25-2013
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Skeletogenesis is initiated during fetal development and persists through adult life as either a remodeling process in response to homeostatic regulation or as a regenerative process in response to physical injury. Mesenchymal stem cells (MSCs) play a crucial role providing progenitor cells from which osteoblasts, bone matrix forming cells are differentiated. The mechanical environment plays an important role in regulating stem cell differentiation into osteoblasts, however, the mechanisms by which MSCs respond to mechanical stimuli are yet to be fully elucidated. To increase understanding of MSC mechanotransuction and osteogenic differentiation, this study aimed to identify novel, mechanically augmented genes and pathways with pro-osteogenic functionality. Using collagen glycoaminoglycan scaffolds as mimics of native extracellular matrix, to create a 3D environment more representative of that found in bone, MSC-seeded constructs were mechanically stimulated in a flow-perfusion bioreactor. Global gene expression profiling techniques were used to identify potential candidates warranting further investigation. Of these, placental growth factor (PGF) was selected and expression levels were shown to strongly correlate to both the magnitude and duration of mechanical stimulation. We demonstrated that PGF gene expression was modulated through an actin polymerization-mediated mechanism. The functional role of PGF in modulating MSC osteogenic differentiation was interrogated, and we showed a concentration-dependent response whereby low concentrations exhibited the strongest pro-osteogenic effect. Furthermore, pre-osteoclast migration and differentiation, as well as endothelial cell tubule formation also maintained concentration-dependent responses to PGF, suggesting a potential role for PGF in bone resorption and angiogenesis, processes key to bone remodeling and fracture repair.
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Genome sequence reveals that Pseudomonas fluorescens F113 possesses a large and diverse array of systems for rhizosphere function and host interaction.
BMC Genomics
PUBLISHED: 01-23-2013
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Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar-beet rhizosphere. This bacterium has been extensively studied as a model strain for genetic regulation of secondary metabolite production in P. fluorescens, as a candidate biocontrol agent against phytopathogens, and as a heterologous host for expression of genes with biotechnological application. The F113 genome sequence and annotation has been recently reported.
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Patterns of Internet and smartphone use by parents of children attending a pediatric otolaryngology service.
Int. J. Pediatr. Otorhinolaryngol.
PUBLISHED: 01-16-2013
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To assess Internet use and the influence of smartphones on health-information seeking by parents and carers of children with ENT conditions.
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Characterization of the SPI-1 and Rsp type three secretion systems in Pseudomonas fluorescens F113.
Environ Microbiol Rep
PUBLISHED: 01-10-2013
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Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar beet rhizosphere. The recent annotation of the F113 genome sequence has revealed that this strain encodes a wide array of secretion systems, including two complete type three secretion systems (T3SSs) belonging to the Hrp1 and SPI-1 families. While Hrp1 T3SSs are frequently encoded in other P. fluorescens strains, the presence of a SPI-1 T3SS in a plant-beneficial bacterial strain was unexpected. In this work, the genetic organization and expression of these two T3SS loci have been analysed by a combination of transcriptional reporter fusions and transcriptome analyses. Overexpression of two transcriptional activators has shown a number of genes encoding putative T3 effectors. In addition, the influence of these two T3SSs during the interaction of P.?fluorescens F113 with some bacterial predators was also assessed. Our data revealed that the transcriptional activator hilA is induced by amoeba and that the SPI-1 T3SS could potentially be involved in resistance to amoeboid grazing.
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Archaea Appear to Dominate the Microbiome of Inflatella pellicula Deep Sea Sponges.
PLoS ONE
PUBLISHED: 01-01-2013
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Microbes associated with marine sponges play significant roles in host physiology. Remarkable levels of microbial diversity have been observed in sponges worldwide through both culture-dependent and culture-independent studies. Most studies have focused on the structure of the bacterial communities in sponges and have involved sponges sampled from shallow waters. Here, we used pyrosequencing of 16S rRNA genes to compare the bacterial and archaeal communities associated with two individuals of the marine sponge Inflatella pellicula from the deep-sea, sampled from a depth of 2,900 m, a depth which far exceeds any previous sequence-based report of sponge-associated microbial communities. Sponge-microbial communities were also compared to the microbial community in the surrounding seawater. Sponge-associated microbial communities were dominated by archaeal sequencing reads with a single archaeal OTU, comprising ?60% and ?72% of sequences, being observed from Inflatella pellicula. Archaeal sequencing reads were less abundant in seawater (?11% of sequences). Sponge-associated microbial communities were less diverse and less even than any other sponge-microbial community investigated to date with just 210 and 273 OTUs (97% sequence identity) identified in sponges, with 4 and 6 dominant OTUs comprising ?88% and ?89% of sequences, respectively. Members of the candidate phyla, SAR406, NC10 and ZB3 are reported here from sponges for the first time, increasing the number of bacterial phyla or candidate divisions associated with sponges to 43. A minor cohort from both sponge samples (?0.2% and ?0.3% of sequences) were not classified to phylum level. A single OTU, common to both sponge individuals, dominates these unclassified reads and shares sequence homology with a sponge associated clone which itself has no known close relative and may represent a novel taxon.
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Effects of maternal obstructive sleep apnoea on fetal growth: a prospective cohort study.
PLoS ONE
PUBLISHED: 01-01-2013
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The objective of this study is to determine whether obstructive sleep apnea (OSA) is associated with reduced fetal growth, and whether nocturnal oxygen desaturation precipitates acute fetal heart rate changes.
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Non-viral gene-activated matrices: next generation constructs for bone repair.
Organogenesis
PUBLISHED: 01-01-2013
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In the context of producing enhanced therapeutics for regenerative medicine, our laboratory develops gene-activated matrices (GAMs) using non-viral gene therapy (GT) in combination with collagen-based scaffolds engineered specifically for tissue repair. Non-viral vectors have been referred to as a minority pursuit in GT but considering the concerns associated with viral vectors and as transient gene expression is such a key consideration, further research is clearly warranted for tissue engineering (TE) applications. Mesenchymal stem cells (MSCs) are well regarded for their capability in bone regeneration but as primary cells, they are difficult to transfect. We have recently optimised the non-viral vector, polyethyleneimine (PEI), to achieve high transfection efficiencies in MSCs. Subsequently, a series of PEI-based GAMs were developed using collagen, collagen-glycosaminoglycan and collagen-nanohydroxyapatite (collagen-nHa) scaffolds whereby transgene expression was detected up to 21 d with the collagen-nHa scaffold providing the most prolonged expression. Moreover, all PEI-based GAMs contained a low plasmid DNA dose of 2 µg which is far below doses often required in previous GAMs. Having successfully developed these GAMs, the ephrinB2 gene has recently been incorporated to produce a novel therapeutic GAM for bone repair. Herein, we discuss our recent investigations in the development and application of non-viral GAMs.
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Treating obstructive sleep apnea with hypoglossal nerve stimulation.
Sleep
PUBLISHED: 11-02-2011
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Reduced upper airway muscle activity during sleep is fundamental to obstructive sleep apnea (OSA) pathogenesis. Hypoglossal nerve stimulation (HGNS) counteracts this problem, with potential to reduce OSA severity.
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A high-throughput screen to identify novel calcineurin inhibitors.
J. Microbiol. Methods
PUBLISHED: 08-29-2011
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Calcineurin is a eukaryotic protein phosphatase important for many signalling and developmental processes in cells. Inhibitors of this enzyme are used clinically and there is interest in identifying novel inhibitors for therapeutic applications. This report describes a high-throughput assay that can be used to screen natural or chemical libraries of compounds to identify new calcineurin inhibitors. The microtitre plate assay is based on a yeast reporter strain and was validated with known inhibitors and tested in a pilot screen of bacterial extracts.
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Addition of hyaluronic acid improves cellular infiltration and promotes early-stage chondrogenesis in a collagen-based scaffold for cartilage tissue engineering.
J Mech Behav Biomed Mater
PUBLISHED: 08-26-2011
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The response of mesenchymal stem cells (MSCs) to a matrix largely depends on the composition as well as the extrinsic mechanical and morphological properties of the substrate to which they adhere to. Collagen-glycosaminoglycan (CG) scaffolds have been extensively used in a range of tissue engineering applications with great success. This is due in part to the presence of the glycosaminoglycans (GAGs) in complementing the biofunctionality of collagen. In this context, the overall goal of this study was to investigate the effect of two GAG types: chondroitin sulphate (CS) and hyaluronic acid (HyA) on the mechanical and morphological characteristics of collagen-based scaffolds and subsequently on the differentiation of rat MSCs in vitro. Morphological characterisation revealed that the incorporation of HyA resulted in a significant reduction in scaffold mean pore size (93.9 ?m) relative to collagen-CS (CCS) scaffolds (136.2 ?m). In addition, the collagen-HyA (CHyA) scaffolds exhibited greater levels of MSC infiltration in comparison to the CCS scaffolds. Moreover, these CHyA scaffolds showed significant acceleration of early stage gene expression of SOX-9 (approximately 60-fold higher, p<0.01) and collagen type II (approximately 35-fold higher, p<0.01) as well as cartilage matrix production (7-fold higher sGAG content) in comparison to CCS scaffolds by day 14. Combining their ability to stimulate MSC migration and chondrogenesis in vitro, these CHyA scaffolds show great potential as appropriate matrices for promoting cartilage tissue repair.
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Low oxygen induces the type III secretion system in Pseudomonas aeruginosa via modulation of the small RNAs rsmZ and rsmY.
Microbiology (Reading, Engl.)
PUBLISHED: 08-26-2011
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A steep oxygen gradient within the mucus of the cystic fibrosis (CF) lung combined with the biofilm mode of bacterial growth forces respiratory pathogens to adapt to varying oxygen availability. This study presents the novel finding that the Pseudomonas aeruginosa response to limiting oxygen stress includes induction of its type III secretion system (T3SS), which subsequently contributes towards host cell cytotoxicity. In P. aeruginosa, the global anaerobic response regulator Anr perceives low oxygen and subsequently triggers gene expression of a range of target genes, including the response regulator narL. Here we demonstrate that microaerobic induction of the T3SS is dependent on Anr, and that this is mediated through direct NarL transcriptional repression of the sRNAs rsmY and rsmZ, allowing free RsmA protein to positively regulate the T3SS. This study reveals a novel interplay between the Anr-NarL and RsmAYZ regulatory circuits, and introduces RsmA as an important regulator during P. aeruginosa adaptation to a low-oxygen environment.
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Mesenchymal stem cell fate is regulated by the composition and mechanical properties of collagen-glycosaminoglycan scaffolds.
J Mech Behav Biomed Mater
PUBLISHED: 08-19-2011
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In stem cell biology, focus has recently turned to the influence of the intrinsic properties of the extracellular matrix (ECM), such as structural, composition and elasticity, on stem cell differentiation. Utilising collagen-glycosaminoglycan (CG) scaffolds as an analogue of the ECM, this study set out to determine the effect of scaffold stiffness and composition on naive mesenchymal stem cell (MSC) differentiation in the absence of differentiation supplements. Dehydrothermal (DHT) and 1-ethyl-3-3-dimethyl aminopropyl carbodiimide (EDAC) crosslinking treatments were used to produce three homogeneous CG scaffolds with the same composition but different stiffness values: 0.5, 1 and 1.5 kPa. In addition, the effect of scaffold composition on MSC differentiation was investigated by utilising two glycosaminoglycan (GAG) types: chondroitin sulphate (CS) and hyaluronic acid (HyA). Results demonstrated that scaffolds with the lowest stiffness (0.5 kPa) facilitated a significant up-regulation in SOX9 expression indicating that MSCs are directed towards a chondrogenic lineage in more compliant scaffolds. In contrast, the greatest level of RUNX2 expression was found in the stiffest scaffolds (1.5 kPa) indicating that MSCs are directed towards an osteogenic lineage in stiffer scaffolds. Furthermore, results demonstrated that the level of up-regulation of SOX9 was higher within the CHyA scaffolds in comparison to the CCS scaffolds indicating that hyaluronic acid further influences chondrogenic differentiation. In contrast, enhanced RUNX2 expression was observed in the CCS scaffolds in comparison to the CHyA scaffolds suggesting an osteogenic influence of chondroitin sulphate on MSC differentiation. In summary, this study demonstrates that, even in the absence of differentiation supplements, scaffold stiffness can direct the fate of MSCs, an effect that is further enhanced by the GAG type used within the CG scaffolds. These results have significant implications for the therapeutic uses of stem cells and enhance our understanding of the physical effects of the in vivo microenvironment on stem cell behaviour.
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Detection of the Pseudomonas Quinolone Signal (PQS) by cyclic voltammetry and amperometry using a boron doped diamond electrode.
Chem. Commun. (Camb.)
PUBLISHED: 08-19-2011
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2-Heptyl-3-hydroxy-4-quinolone, known as the Pseudomonas Quinolone Signal, is a key regulator of bacterial cooperative behaviour known as quorum sensing. A simple electrochemical strategy was employed for its sensitive detection using a bare boron-doped diamond electrode by cyclic voltammetry and amperometry. PQS (and potentially other quinolones) was then detected in cultures of P. aeruginosa pqsL(-) mutant strains.
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Work adjustment in cardiovascular disease: job characteristics and social support.
J Cardiopulm Rehabil Prev
PUBLISHED: 08-10-2011
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To better understand social influences on work recovery, we studied the association between work status, work adjustment (WA), job demands, and social support (employer, family, physician) for return to work in cardiac rehabilitation (CR) patients.
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The development of non-viral gene-activated matrices for bone regeneration using polyethyleneimine (PEI) and collagen-based scaffolds.
J Control Release
PUBLISHED: 08-09-2011
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The healing potential of scaffolds for tissue engineering can be enhanced by combining them with genes to produce gene-activated matrices (GAMs) for tissue regeneration. We examined the potential of using polyethyleneimine (PEI) as a vector for transfection of mesenchymal stem cells (MSCs) in monolayer culture and in 3D collagen-based GAMs. PEI-pDNA polyplexes were fabricated at a range of N/P ratios and their optimal transfection parameters (N/P 7 ratio, 2?g dose) and transfection efficiencies (30±8%) determined in monolayer culture. The polyplexes were then loaded onto collagen, collagen-glycosaminoglycan and collagen-nanohydroxyapatite scaffolds where gene expression was observed up to 21 days with a polyplex dose as low as 2?g. Transient expression profiles indicated that the GAMs act as a polyplex depot system whereby infiltrating cells become transfected over time as they migrate throughout the scaffold. The collagen-nHa GAM exhibited the most prolonged and elevated levels of transgene expression. This research has thus demonstrated that PEI is a highly efficient pDNA transfection agent for both MSC monolayer cultures and in the 3D GAM environment. By combining therapeutic gene therapy with highly engineered scaffolds, it is proposed that these GAMs might have immense capability to promote tissue regeneration.
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Implications of interspecies signaling for virulence of bacterial and fungal pathogens.
Future Microbiol
PUBLISHED: 07-30-2011
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Despite the broad armory of vaccines, antibiotics and other weapons at our disposal, pathogenic bacteria and fungi continue to present a serious threat to human health. These pathogens have proved very versatile and many are associated with infections of vulnerable individuals, often in hospital settings. Evidence is accumulating that certain infections, for example, of medical devices, the cystic fibrosis lung, the oral cavity, the GI tract and wounds, are in fact polymicrobial, with more than one microbe involved. To understand diseases and formulate intervention strategies, it is necessary to know the extent of contact and communication between microbes in these mixed infections. It is now emerging that the signals that microbes use to coordinate expression of viruence factors within a species may also be perceived by other microbes in the community. This article addresses such interspecies signaling and examines the consequences of such signaling between bacterial and fungal pathogens for expression of virulence traits.
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The Pseudomonas quinolone signal (PQS), and its precursor HHQ, modulate interspecies and interkingdom behaviour.
FEMS Microbiol. Ecol.
PUBLISHED: 05-26-2011
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The Pseudomonas quinolone signal (PQS), and its precursor 2-heptyl-4-quinolone (HHQ), play a key role in coordinating virulence in the important cystic fibrosis pathogen Pseudomonas aeruginosa. The discovery of HHQ analogues in Burkholderia and other microorganisms led us to investigate the possibility that these compounds can influence interspecies behaviour. We found that surface-associated phenotypes were repressed in Gram-positive and Gram-negative bacteria as well as in pathogenic yeast in response to PQS and HHQ. Motility was repressed in a broad range of bacteria, while biofilm formation in Bacillus subtilis and Candida albicans was repressed in the presence of HHQ, though initial adhesion was unaffected. Furthermore, HHQ exhibited potent bacteriostatic activity against several Gram-negative bacteria, including pathogenic Vibrio vulnificus. Structure-function analysis using synthetic analogues provided an insight into the molecular properties that underpin the ability of these compounds to influence microbial behaviour, revealing the alkyl chain to be fundamental. Defining the influence of these molecules on microbial-eukaryotic-host interactions will facilitate future therapeutic strategies which seek to combat microorganisms that are recalcitrant to conventional antimicrobial agents.
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Genomic analysis of the type VI secretion systems in Pseudomonas spp.: novel clusters and putative effectors uncovered.
Microbiology (Reading, Engl.)
PUBLISHED: 04-07-2011
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Bacteria encode multiple protein secretion systems that are crucial for interaction with the environment and with hosts. In recent years, attention has focused on type VI secretion systems (T6SSs), which are specialized transporters widely encoded in Proteobacteria. The myriad of processes associated with these secretion systems could be explained by subclasses of T6SS, each involved in specialized functions. To assess diversity and predict function associated with different T6SSs, comparative genomic analysis of 34 Pseudomonas genomes was performed. This identified 70 T6SSs, with at least one locus in every strain, except for Pseudomonas stutzeri A1501. By comparing 11 core genes of the T6SS, it was possible to identify five main Pseudomonas phylogenetic clusters, with strains typically carrying T6SSs from more than one clade. In addition, most strains encode additional vgrG and hcp genes, which encode extracellular structural components of the secretion apparatus. Using a combination of phylogenetic and meta-analysis of transcriptome datasets it was possible to associate specific subsets of VgrG and Hcp proteins with each Pseudomonas T6SS clade. Moreover, a closer examination of the genomic context of vgrG genes in multiple strains highlights a number of additional genes associated with these regions. It is proposed that these genes may play a role in secretion or alternatively could be new T6S effectors.
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The Hounsfield value for cortical bone geometry in the proximal humerus--an in vitro study.
Skeletal Radiol.
PUBLISHED: 03-15-2011
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Fractures of the proximal humerus represent a major osteoporotic burden. Recent developments in CT imaging have emphasized the importance of cortical bone thickness distribution in the prevention and management of fragility fractures. We aimed to experimentally define the CT density of cortical bone in the proximal humerus for building cortical geometry maps.
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Staphylococcus aureus protein A binds to osteoblasts and triggers signals that weaken bone in osteomyelitis.
PLoS ONE
PUBLISHED: 03-09-2011
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Osteomyelitis is a debilitating infectious disease of the bone. It is predominantly caused by S. aureus and is associated with significant morbidity and mortality. It is characterised by weakened bones associated with progressive bone loss. Currently the mechanism through which either bone loss or bone destruction occurs in osteomyelitis patients is poorly understood. We describe here for the first time that the major virulence factor of S. aureus, protein A (SpA) binds directly to osteoblasts. This interaction prevents proliferation, induces apoptosis and inhibits mineralisation of cultured osteoblasts. Infected osteoblasts also increase the expression of RANKL, a key protein involved in initiating bone resorption. None of these effects was seen in a mutant of S. aureus lacking SpA. Complementing the SpA-defective mutant with a plasmid expressing spa or using purified protein A resulted in attachment to osteoblasts, inhibited proliferation and induced apoptosis to a similar extent as wildtype S. aureus. These events demonstrate mechanisms through which loss of bone formation and bone weakening may occur in osteomyelitis patients. This new information may pave the way for the development of new and improved therapeutic agents to treat this disease.
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Impaired expression of hypoxia-inducible factor-1? in cystic fibrosis airway epithelial cells - a role for HIF-1 in the pathophysiology of CF?
J. Cyst. Fibros.
PUBLISHED: 02-18-2011
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The continuous infection-inflammation cycle plays a crucial role in the progression of cystic fibrosis (CF) disease. This noxious loop can be aggravated by a reduced partial pressure of oxygen in the blood, hypoxemia, present in CF patients. These interconnected factors, hypoxia, inflammation and infection, by stabilizing the hypoxia-inducible factor-1? (HIF-1?) protein subunit, are able to activate the transcription factor HIF-1. To date, data investigating the potential role of HIF-1 in CF are scarce. Our results demonstrated that HIF-1? protein expression was altered in CF-affected compared to CFTR-corrected airway epithelial cells in unsimulated and simulated hypoxic conditions. In contrast, when CF-affected cells were infected with Pseudomonas aeruginosa, HIF-1? was more stabilized compared to CFTR-corrected cells. As HIF-1 is linked with an efficient immune response and pulmonary complications in cystic fibrosis, this difference in HIF-1? protein levels could have an impact in the CF pathology and the persistence of P. aeruginosa infection.
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In-vivo generation of bone via endochondral ossification by in-vitro chondrogenic priming of adult human and rat mesenchymal stem cells.
BMC Musculoskelet Disord
PUBLISHED: 01-31-2011
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Bone grafts are required to repair large bone defects after tumour resection or large trauma. The availability of patients own bone tissue that can be used for these procedures is limited. Thus far bone tissue engineering has not lead to an implant which could be used as alternative in bone replacement surgery. This is mainly due to problems of vascularisation of the implanted tissues leading to core necrosis and implant failure. Recently it was discovered that embryonic stem cells can form bone via the endochondral pathway, thereby turning in-vitro created cartilage into bone in-vivo. In this study we investigated the potential of human adult mesenchymal stem cells to form bone via the endochondral pathway.
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The effect of sleep deprivation on BOLD activity elicited by a divided attention task.
Brain Imaging Behav
PUBLISHED: 01-29-2011
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Sleep loss, widespread in todays society and associated with a number of clinical conditions, has a detrimental effect on a variety of cognitive domains including attention. This study examined the sequelae of sleep deprivation upon BOLD fMRI activation during divided attention. Twelve healthy males completed two randomized sessions; one after 27 h of sleep deprivation and one after a normal night of sleep. During each session, BOLD fMRI was measured while subjects completed a cross-modal divided attention task (visual and auditory). After normal sleep, increased BOLD activation was observed bilaterally in the superior frontal gyrus and the inferior parietal lobe during divided attention performance. Subjects reported feeling significantly more sleepy in the sleep deprivation session, and there was a trend towards poorer divided attention task performance. Sleep deprivation led to a down regulation of activation in the left superior frontal gyrus, possibly reflecting an attenuation of top-down control mechanisms on the attentional system. These findings have implications for understanding the neural correlates of divided attention and the neurofunctional changes that occur in individuals who are sleep deprived.
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Three hours of perfusion culture prior to 28 days of static culture, enhances osteogenesis by human cells in a collagen GAG scaffold.
Biotechnol. Bioeng.
PUBLISHED: 01-25-2011
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In tissue engineering, bioreactors can be used to aid in the in vitro development of new tissue by providing biochemical and physical regulatory signals to cells and encouraging them to undergo differentiation and/or to produce extracellular matrix prior to in vivo implantation. This study examined the effect of short term flow perfusion bioreactor culture, prior to long-term static culture, on human osteoblast cell distribution and osteogenesis within a collagen glycosaminoglycan (CG) scaffold for bone tissue engineering. Human fetal osteoblasts (hFOB 1.19) were seeded onto CG scaffolds and pre-cultured for 6 days. Constructs were then placed into the bioreactor and exposed to 3?×?1?h bouts of steady flow (1?mL/min) separated by 7?h of no flow over a 24-h period. The constructs were then cultured under static osteogenic conditions for up to 28 days. Results show that the bioreactor and static culture control groups displayed similar cell numbers and metabolic activity. Histologically, however, peripheral cell-encapsulation was observed in the static controls, whereas, improved migration and homogenous cell distribution was seen in the bioreactor groups. Gene expression analysis showed that all osteogenic markers investigated displayed greater levels of expression in the bioreactor groups compared to static controls. While static groups showed increased mineral deposition; mechanical testing revealed that there was no difference in the compressive modulus between bioreactor and static groups. In conclusion, a flow perfusion bioreactor improved construct homogeneity by preventing peripheral encapsulation whilst also providing an enhanced osteogenic phenotype over static controls.
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Transcutaneous measurement of carbon dioxide tension during extended monitoring: evaluation of accuracy and stability, and an algorithm for correcting calibration drift.
Respir Care
PUBLISHED: 01-21-2011
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When polysomnography is indicated in a patient with a presumed sleep disorder, continuous monitoring of arterial carbon dioxide tension (P(aCO(2))) is desirable, especially if nocturnal hypoventilation is suspected. Transcutaneous CO(2) monitors (P(tcCO(2))) provide a noninvasive correlate of P(aCO(2)), but their accuracy and stability over extended monitoring have been considered inadequate for the diagnosis of hypoventilation. We examined the stability and accuracy of P(tcCO(2)) measurements and the performance of a previously described linear interpolation technique designed to correct for calibration drift.
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Bioreactors in tissue engineering.
Technol Health Care
PUBLISHED: 01-21-2011
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A bioreactor can be defined as a device that uses mechanical means to influence biological processes. In tissue engineering bioreactors can be used to aid in the in vitro development of new tissue by providing biochemical and physical regulatory signals to cells and encouraging them to undergo differentiation and/or to produce extracellular matrix prior to in vivo implantation. This chapter discusses the necessity for bioreactors in tissue engineering, the numerous types of bioreactor that exist, the means by which they stimulate cells and how their functionality is governed by the requirements of the specific tissue being engineered and the cell type undergoing stimulation.
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Crosslinking and mechanical properties significantly influence cell attachment, proliferation, and migration within collagen glycosaminoglycan scaffolds.
Tissue Eng Part A
PUBLISHED: 01-17-2011
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Crosslinking and the resultant changes in mechanical properties have been shown to influence cellular activity within collagen biomaterials. With this in mind, we sought to determine the effects of crosslinking on both the compressive modulus of collagen-glycosaminoglycan scaffolds and the activity of osteoblasts seeded within them. Dehydrothermal, 1-ethyl-3-3-dimethyl aminopropyl carbodiimide and glutaraldehyde crosslinking treatments were first investigated for their effect on the compressive modulus of the scaffolds. After this, the most promising treatments were used to study the effects of crosslinking on cellular attachment, proliferation, and infiltration. Our experiments have demonstrated that a wide range of scaffold compressive moduli can be attained by varying the parameters of the crosslinking treatments. 1-Ethyl-3-3-dimethyl aminopropyl carbodiimide and glutaraldehyde treatments produced the stiffest scaffolds (fourfold increase when compared to dehydrothermal crosslinking). When cells were seeded onto the scaffolds, the stiffest scaffolds also showed increased cell number and enhanced cellular distribution when compared to the other groups. Taken together, these results indicate that crosslinking can be used to produce collagen-glycosaminoglycan scaffolds with a range of compressive moduli, and that increased stiffness enhances cellular activity within the scaffolds.
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Towards in vitro vascularisation of collagen-GAG scaffolds.
Eur Cell Mater
PUBLISHED: 01-13-2011
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Collagen-glycosaminoglycan scaffolds that have been used clinically for skin regeneration have also shown significant promise for other applications in tissue engineering. However, regeneration of thicker tissues with the aid of implanted biomaterials is likely to depend on, or be accelerated by, the ability to establish rapid vascularisation of the implant. The present study aims to establish a nascent vascular network in vitro within a CG scaffold as a first step towards that goal. Mesenchymal stem cells (MSCs) were chosen as primary vasculogenic candidate cells and a culture medium that promoted maximal network formation on Matrigel by these cells was selected. MSCs seeded in the CG scaffold formed networks of cord-like structures after one to two weeks in the presence of the vasculogenic medium; similar structures were formed by aortic endothelial cells (ECs) cultured for comparison. Gene expression analysis suggested that the MSCs began to adopt an endothelial phenotype, with RNA for PECAM and VCAM rising while that for alpha-smooth muscle actin fell. However there was no increase in Tie-2 and vWF expression. Addition of smooth muscle cells (SMCs) as a potential perivascular stabilising component did not have a noticeable effect on MSC-derived networks, although it enhanced EC-derived structures.
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The marine-derived, multi-mineral formula, Aquamin, enhances mineralisation of osteoblast cells in vitro.
Phytother Res
PUBLISHED: 01-06-2011
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Osteoporosis is a global health problem characterized by low bone mass and an increase in bone fragility. It is now well accepted that dietary factors play a central role in bone development and health. Diet that lacks adequate minerals is considered to be a risk factor for osteoporosis. The food supplement, Aquamin, is a natural, multi-mineral derived from the red algae Lithothamnion corallioides, rich in calcium, magnesium and 72 other trace minerals. The aim of this study was to evaluate the effect of Aquamin on osteoblastic behaviour and mineralisation in a pre-osteoblastic cell line. Cell number and metabolic activity were assessed using Hoescht DNA and AlamarBlue assays respectively. Osteogenic differentiation was measured using an alkaline phosphatase assay while mineralisation was determined using von Kossa and alizarin red staining. It is reported here that Aquamin promotes increased mineralisation in osteoblast cell culture. These data suggest that the nutritional supplement Aquamin plays an important role in promoting bone formation and may be useful in treating bone diseases such as osteoporosis.
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The 2007 AASM recommendations for EEG electrode placement in polysomnography: impact on sleep and cortical arousal scoring.
Sleep
PUBLISHED: 01-05-2011
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To examine the impact of using American Academy of Sleep Medicine (AASM) recommended EEG derivations (F4/M1, C4/M1, O2/M1) vs. a single derivation (C4/M1) in polysomnography (PSG) on the measurement of sleep and cortical arousals, including inter- and intra-observer variability.
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Tetracycline resistance-encoding plasmid from Bacillus sp. strain #24, isolated from the marine sponge Haliclona simulans.
Appl. Environ. Microbiol.
PUBLISHED: 11-05-2010
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Knowledge of the nature of resistance determinants in natural habitats is fundamental to increasing our understanding of the development of antibiotic resistance in clinical settings. Here we provide the first report of a tetracycline resistance-encoding plasmid, pBHS24, from a marine sponge-associated bacterium, Bacillus sp. strain #24, isolated from Haliclona simulans.
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