76 results on '"Powell LC"'
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2. Resource Use Related to Pediatric Lower Limb Spasticity in Canada: Physician Questionnaire
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Powell, LC, primary, Johnston, KM, additional, Liovas, A, additional, Chong, M, additional, Danchenko, N, additional, and Dinet, J, additional
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- 2018
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3. PND37 - Resource Use Related to Pediatric Lower Limb Spasticity in Canada: Physician Questionnaire
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Powell, LC, Johnston, KM, Liovas, A, Chong, M, Danchenko, N, and Dinet, J
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- 2018
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4. CONDYLOMA ACUMINATUM
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Powell Lc
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business.industry ,Cancer research ,medicine ,Obstetrics and Gynecology ,Condyloma Acuminatum ,Carcinogenesis ,medicine.disease_cause ,business - Published
- 1978
5. Development of a General Composite Scale (GENCOMS) for Progressive Neurodegenerative Diseases and Implications for the Assessment of Disease-Modifying Therapies.
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Dickson SP, Mallinckrodt CH, Rogula B, Powell LC, Potashman MH, Coric V, L'Italien GJ, and Hendrix SB
- Abstract
Introduction: The reliable assessment of treatment outcomes for disease-modifying therapies (DMT) in neurodegenerative disease is challenging. The objective of this paper is to describe a generalized framework for developing composite scales that can be applied in diverse, degenerative conditions, termed "GENCOMS." Composite scales optimize the sensitivity for detecting clinically meaningful effects that slow disease progression., Methods: The GENCOMS method relies on robust natural history data and/or placebo arm data from DMT trials. Validated scales that are core to the disease process have been identified, and item level data obtained to standardize the response outcomes from 0 (best possible score) to 1 (worst possible score). A partial least squares regression analysis was conducted with temporal change as the dependent variable and change scores in standardized items as the explanatory variables. The derived model coefficients constitute a weighted sum of items that most effectively measure disease progression., Results: The resultant composite scale was optimized to detect disease progression and can be examined in a range of slow or fast progressing populations. The scale can be used in studies with comparable patient populations as an endpoint optimized to measure disease progression and therefore ideally suited to assess treatment effects in DMTs., Conclusion: The methodology presented here provides a generalizable framework for developing composite scales in the assessment of neurodegenerative disease progression and evaluation of DMT effects. By objectively selecting and weighting items from previously validated measures based solely on their sensitivity to disease progression, this methodology allows for the creation of a more responsive measurement of clinical decline. This heightened sensitivity to clinical decline can be utilized to detect modest yet meaningful treatment effects in the early stages of neurogenerative diseases, when it is optimal to begin a DMT., (© 2024. The Author(s).)
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- 2024
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6. Cost-effectiveness of rimegepant oral lyophilisate compared to best supportive care for the acute treatment of migraine in the UK.
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Johnston K, Powell LC, Popoff E, L'Italien GJ, Pawinski R, Ahern A, Large S, Tran T, and Jenkins A
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- Humans, United Kingdom, Adult, Male, Female, Markov Chains, Administration, Oral, Middle Aged, Migraine Disorders drug therapy, Migraine Disorders economics, Cost-Benefit Analysis, Quality-Adjusted Life Years, Piperidines therapeutic use, Piperidines economics, Piperidines administration & dosage, Pyridines therapeutic use, Pyridines economics
- Abstract
Aims: Migraine is the most common disabling headache disorder and is characterized by recurrent throbbing head pain and symptoms of photophobia, phonophobia, nausea, and vomiting. Rimegepant 75 mg, an oral lyophilisate calcitonin gene-related peptide antagonist, is the first treatment approved for both the acute and preventative treatment of migraine, and the first acute therapy approved in over 20-years. The objective was to assess the cost-utility of rimegepant compared with best supportive care (BSC) in the UK, for the acute treatment of migraine in the adults with inadequate symptom relief after taking at least 2 triptans, or for whom triptans are contraindicated or not tolerated., Materials and Methods: A de novo model was developed to estimate incremental costs and quality-adjusted life years (QALYs), structured as a decision tree followed by Markov model. Patients received rimegepant or BSC for a migraine attack and were assessed for response (pain relief at 2-h). Responders and non-responders followed different pain trajectories over 48-h cycles. Non-responders discontinued treatment while responders continued treatment for subsequent attacks, with a proportion discontinuing over time. Data sources included a post-hoc pooled analysis of the phase 3 acute rimegepant trials (NCT03235479, NCT03237845, NCT03461757), and a long-term safety study (NCT03266588). The analysis was conducted from the perspective of the UK National Health Service and Personal Social Services over a 20-year time horizon., Results: Rimegepant resulted in an incremental cost-utility ratio (ICUR) of £10,309 per QALY gained vs BSC, which is cost-effectiveness at a willingness to pay threshold of £30,000/QALY. Rimegepant generated +0.44 incremental QALYs and higher incremental lifetime costs (£4,492). Improved QALYs for rimegepant were a result of less time spent with severe and moderate headache pain., Conclusion: This study highlights the economic value of rimegepant which was found to be cost-effective for the acute treatment of migraine in adults unsuitable for triptans.
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- 2024
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7. Structure-Activity Relationships of Low Molecular Weight Alginate Oligosaccharide Therapy against Pseudomonas aeruginosa .
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Pritchard MF, Powell LC, Adams JYM, Menzies G, Khan S, Tøndervik A, Sletta H, Aarstad O, Skjåk-Bræk G, McKenna S, Buurma NJ, Farnell DJJ, Rye PD, Hill KE, and Thomas DW
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- Molecular Weight, Structure-Activity Relationship, Anti-Bacterial Agents pharmacology, Pseudomonas aeruginosa, Alginates pharmacology
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Low molecular weight alginate oligosaccharides have been shown to exhibit anti-microbial activity against a range of multi-drug resistant bacteria, including Pseudomonas aeruginosa . Previous studies suggested that the disruption of calcium (Ca
2+ )-DNA binding within bacterial biofilms and dysregulation of quorum sensing (QS) were key factors in these observed effects. To further investigate the contribution of Ca2+ binding, G-block (OligoG) and M-block alginate oligosaccharides (OligoM) with comparable average size DPn 19 but contrasting Ca2+ binding properties were prepared. Fourier-transform infrared spectroscopy demonstrated prolonged binding of alginate oligosaccharides to the pseudomonal cell membrane even after hydrodynamic shear treatment. Molecular dynamics simulations and isothermal titration calorimetry revealed that OligoG exhibited stronger interactions with bacterial LPS than OligoM, although this difference was not mirrored by differential reductions in bacterial growth. While confocal laser scanning microscopy showed that both agents demonstrated similar dose-dependent reductions in biofilm formation, OligoG exhibited a stronger QS inhibitory effect and increased potentiation of the antibiotic azithromycin in minimum inhibitory concentration and biofilm assays. This study demonstrates that the anti-microbial effects of alginate oligosaccharides are not purely influenced by Ca2+ -dependent processes but also by electrostatic interactions that are common to both G-block and M-block structures.- Published
- 2023
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8. Defining in vitro topical antimicrobial and antibiofilm activity of epoxy-tigliane structures against oral pathogens.
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Xue W, Pritchard MF, Khan S, Powell LC, Stokniene J, Wu J, Claydon N, Reddell P, Thomas DW, and Hill KE
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Background: Peri-implantitis has become an inexorable clinical challenge in implantology. Topical immunomodulatory epoxy-tiglianes (EBCs), derived from the Queensland blushwood tree, which induce remodeling and resolve dermal infection via induction of the inflammasome and biofilm disruption, may offer a novel therapeutic approach., Design: In vitro antimicrobial activity of EBC structures (EBC-46, EBC-1013 and EBC-147) against Streptococcus mutans , Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in minimum inhibitory concentration, growth curve and permeabilization assays were determined. Antibiofilm activity was assessed using minimum biofilm eradication concentration (MBEC) experiments. Biofilm formation and disruption assays were analyzed using confocal laser scanning microscopy, scanning electron microscopy and direct plate counting., Results: The observed antimicrobial efficacy of the tested compounds (EBC-1013 > EBC-46 > EBC-147) was directly related to significant membrane permeabilization and growth inhibition ( p < 0.05) against planktonic S. mutans and P. gingivalis . Antibiofilm activity was evident in MBEC assays, with S. mutans biofilm formation assays revealing significantly lower biomass volume and increased DEAD:LIVE cell ratio observed for EBC-1013 ( p < 0.05). Furthermore, biofilm disruption assays on titanium discs induced significant biofilm disruption in S. mutans and P. gingivalis ( p < 0.05)., Conclusions: EBC-1013 is a safe, semi-synthetic, compound, demonstrating clear antimicrobial biofilm disruption potential in peri-implantitis., Competing Interests: This work was supported by QBiotics Group Limited, Yungaburra, Australia, who also supplied the EBC compounds used in this study. DWT. KEH, MFP and LCP have received research funding from QBiotics Group. JS is an employee of QBiotics Group. PR is the Executive Director and Chief Scientific Officer of QBiotics Group. The other authors have no conflicts of interest to disclose., (© 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)
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- 2023
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9. Health State Utility Mapping of Rimegepant for the Preventive Treatment of Migraine: Double-Blind Treatment Phase and Open Label Extension (BHV3000-305).
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Powell LC, L'Italien G, Popoff E, Johnston K, O'Sullivan F, Harris L, Croop R, Coric V, and Lipton RB
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- Adult, Humans, Piperidines therapeutic use, Pyridines therapeutic use, Surveys and Questionnaires, Quality of Life, Migraine Disorders drug therapy, Migraine Disorders prevention & control
- Abstract
Introduction: The objectives of this study were to (1) report long-term health-related quality of life (HRQoL) outcomes among patients using rimegepant preventatively in BHV3000-305 (NCT03732638) open-label extension (OLE) and (2) map Migraine-Specific Quality of Life questionnaire version 2.1 (MSQv2) to EQ-5D-3L utility values over the double-blind treatment (DBT; 0-12 weeks) and the OLE (13-64 weeks) to assess the influence of treatment on these values., Methods: This was a post hoc analysis using data from a rimegepant study for the prevention of migraine (BHV3000-305). Adult patients with migraine took either rimegepant 75 mg or placebo every other day (EOD) during the DBT phase. All patients received rimegepant during the OLE. MSQv2 was measured at baseline, weeks 12, 24, and 64. A validated algorithm was used to map MSQv2 scores to EQ-5D utilities., Results: Baseline data were available for 347 patients treated with placebo and 348 treated with rimegepant in the DBT period, who continued to the OLE. Baseline EQ-5D utilities were similar between trial arms: 0.598 for placebo and 0.614 for rimegepant. EQ-5D improved from baseline to week 12 and utilities increased by + 0.09 for placebo and + 0.10 for rimegepant (p value = 0.011). By 24 weeks, at which point patients who were originally randomized to placebo had received rimegepant 75 mg EOD for 12 weeks, HRQoL measures (MSQv2 and EQ-5D) were similar across groups, demonstrating rapid onset of treatment effect. This HRQoL improvement was durable out to 64 weeks., Conclusion: Compared to placebo, treatment with rimegepant 75 mg was associated with greater improvement in EQ-5D utilities during the 12-week DBT phase. Patients originally randomized to placebo experienced a similar improvement in EQ-5D utilities after switching to rimegepant during the OLE, demonstrating that benefits are realized within 12 weeks of active treatment. This preventive effect was durable out to 64 weeks and was associated with an additional increase in HRQoL over time., Trial Registration: NCT03732638., (© 2022. The Author(s).)
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- 2023
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10. Alginate oligosaccharides enhance the antifungal activity of nystatin against candidal biofilms.
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Powell LC, Adams JYM, Quoraishi S, Py C, Oger A, Gazze SA, Francis LW, von Ruhland C, Owens D, Rye PD, Hill KE, Pritchard MF, and Thomas DW
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- Humans, Nystatin pharmacology, Nystatin metabolism, Alginates pharmacology, Alginates chemistry, Alginates metabolism, Candida, Candida tropicalis, Candida glabrata, Biofilms, Oligosaccharides pharmacology, Oligosaccharides chemistry, Adenosine Triphosphate metabolism, Microbial Sensitivity Tests, Antifungal Agents pharmacology, Antifungal Agents chemistry, Candidiasis drug therapy, Candidiasis microbiology
- Abstract
Background: The increasing prevalence of invasive fungal infections in immuno-compromised patients is a considerable cause of morbidity and mortality. With the rapid emergence of antifungal resistance and an inadequate pipeline of new therapies, novel treatment strategies are now urgently required., Methods: The antifungal activity of the alginate oligosaccharide OligoG in conjunction with nystatin was tested against a range of Candida spp. ( C. albicans , C. glabrata , C. parapsilosis , C. auris , C. tropicalis and C. dubliniensis ), in both planktonic and biofilm assays, to determine its potential clinical utility to enhance the treatment of candidal infections. The effect of OligoG (0-6%) ± nystatin on Candida spp. was examined in minimum inhibitory concentration (MIC) and growth curve assays. Antifungal effects of OligoG and nystatin treatment on biofilm formation and disruption were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and ATP cellular viability assays. Effects on the cell membrane were determined using permeability assays and transmission electron microscopy (TEM)., Results: MIC and growth curve assays demonstrated the synergistic effects of OligoG (0-6%) with nystatin, resulting in an up to 32-fold reduction in MIC, and a significant reduction in the growth of C. parapsilosis and C. auris (minimum significant difference = 0.2 and 0.12 respectively). CLSM and SEM imaging demonstrated that the combination treatment of OligoG (4%) with nystatin (1 µg/ml) resulted in significant inhibition of candidal biofilm formation on glass and clinical grade silicone surfaces ( p < 0.001), with increased cell death ( p < 0.0001). The ATP biofilm disruption assay demonstrated a significant reduction in cell viability with OligoG (4%) alone and the combined OligoG/nystatin (MIC value) treatment ( p < 0.04) for all Candida strains tested. TEM studies revealed the combined OligoG/nystatin treatment induced structural reorganization of the Candida cell membrane, with increased permeability when compared to the untreated control ( p < 0.001)., Conclusions: Antimicrobial synergy between OligoG and nystatin against Candida spp. highlights the potential utility of this combination therapy in the prevention and topical treatment of candidal biofilm infections, to overcome the inherent tolerance of biofilm structures to antifungal agents., Competing Interests: DT and KH have received research funding from AlgiPharma AS. PR is the Chief Scientific Officer at AlgiPharma AS. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Powell, Adams, Quoraishi, Py, Oger, Gazze, Francis, von Ruhland, Owens, Rye, Hill, Pritchard and Thomas.)
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- 2023
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11. Topical, immunomodulatory epoxy-tiglianes induce biofilm disruption and healing in acute and chronic skin wounds.
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Powell LC, Cullen JK, Boyle GM, De Ridder T, Yap PY, Xue W, Pierce CJ, Pritchard MF, Menzies GE, Abdulkarim M, Adams JYM, Stokniene J, Francis LW, Gumbleton M, Johns J, Hill KE, Jones AV, Parsons PG, Reddell P, and Thomas DW
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- Animals, Anti-Bacterial Agents pharmacology, Biofilms, Cattle, Humans, Keratinocytes, Mice, Wound Healing, Phorbols
- Abstract
The management of antibiotic-resistant, bacterial biofilm infections in chronic skin wounds is an increasing clinical challenge. Despite advances in diagnosis, many patients do not derive benefit from current anti-infective/antibiotic therapies. Here, we report a novel class of naturally occurring and semisynthetic epoxy-tiglianes, derived from the Queensland blushwood tree ( Fontainea picrosperma) , and demonstrate their antimicrobial activity (modifying bacterial growth and inducing biofilm disruption), with structure/activity relationships established against important human pathogens. In vitro, the lead candidate EBC-1013 stimulated protein kinase C (PKC)-dependent neutrophil reactive oxygen species (ROS) induction and NETosis and increased expression of wound healing-associated cytokines, chemokines, and antimicrobial peptides in keratinocytes and fibroblasts. In vivo, topical EBC-1013 induced rapid resolution of infection with increased matrix remodeling in acute thermal injuries in calves. In chronically infected diabetic mouse wounds, treatment induced cytokine/chemokine production, inflammatory cell recruitment, and complete healing (in six of seven wounds) with ordered keratinocyte differentiation. These results highlight a nonantibiotic approach involving contrasting, orthogonal mechanisms of action combining targeted biofilm disruption and innate immune induction in the treatment of chronic wounds.
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- 2022
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12. Jellyfish Collagen: A Biocompatible Collagen Source for 3D Scaffold Fabrication and Enhanced Chondrogenicity.
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Ahmed Z, Powell LC, Matin N, Mearns-Spragg A, Thornton CA, Khan IM, and Francis LW
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- Animals, Collagen pharmacology, Humans, Tissue Engineering, Aquatic Organisms chemistry, Biocompatible Materials chemistry, Chondrogenesis drug effects, Collagen chemistry, Osteoarthritis therapy, Scyphozoa, Tissue Scaffolds chemistry
- Abstract
Osteoarthritis (OA) is a multifactorial disease leading to degeneration of articular cartilage, causing morbidity in approximately 8.5 million of the UK population. As the dense extracellular matrix of articular cartilage is primarily composed of collagen, cartilage repair strategies have exploited the biocompatibility and mechanical strength of bovine and porcine collagen to produce robust scaffolds for procedures such as matrix-induced chondrocyte implantation (MACI). However, mammalian sourced collagens pose safety risks such as bovine spongiform encephalopathy, transmissible spongiform encephalopathy and possible transmission of viral vectors. This study characterised a non-mammalian jellyfish ( Rhizostoma pulmo ) collagen as an alternative, safer source in scaffold production for clinical use. Jellyfish collagen demonstrated comparable scaffold structural properties and stability when compared to mammalian collagen. Jellyfish collagen also displayed comparable immunogenic responses (platelet and leukocyte activation/cell death) and cytokine release profile in comparison to mammalian collagen in vitro. Further histological analysis of jellyfish collagen revealed bovine chondroprogenitor cell invasion and proliferation in the scaffold structures, where the scaffold supported enhanced chondrogenesis in the presence of TGFβ1. This study highlights the potential of jellyfish collagen as a safe and biocompatible biomaterial for both OA repair and further regenerative medicine applications.
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- 2021
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13. A New Method to Optimize Stent Deployment by High-Definition Intravascular Ultrasound.
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Leesar MA, Saif I, Hagood KL, Powell LC, Hillegass WB, and Brott BC
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- Coronary Angiography, Humans, Stents, Treatment Outcome, Angioplasty, Balloon, Coronary, Ultrasonography, Interventional
- Abstract
Objectives: Optimal stent deployment by intravascular ultrasound (IVUS) improves outcome, but it can only be achieved in 50% of patients. We investigated the feasibility and effect of a new method of stent optimization on optimal stent deployment., Methods: IVUS analyses of 168 coronary segments were performed after angiography-guided stenting (AGS) and stent optimization in 29 patients (30 lesions). Minimum stent area (MSA), stent volume index (SVI), lumen area, external elastic membrane (EEM), and plaque burden (PB) were measured. Stent optimization included post-stent dilation with a balloon sized by high-definition (HD)-IVUS to the distal reference EEM diameter for stent underexpansion or malapposition, and stenting of PB >50% or edge dissection., Results: After AGS, stent deployment was suboptimal in 77% of patients. After stent optimization, MSA and SVI were significantly larger than AGS. Adequate stent expansion - defined as MSA ≥5.4 mm² or ≥90% of distal reference lumen area - was significantly higher after stent optimization vs AGS (87% vs 56%, respectively; P=.02). Optimal stent deployment - a composite of adequate stent expansion, no malapposition, PB <50% at the stent edges, and no edge dissection - was markedly higher after stent optimization vs AGS (87% vs 35%, respectively; P<.01)., Conclusion: After stent deployment and postdilation, stent results were suboptimal in two-thirds of patients. This simple online stent optimization by HD-IVUS was feasible and resulted in optimal stent deployment in the majority of patients. Randomized studies are warranted to compare the rate of optimal stent deployment and outcomes of this strategy vs other techniques.
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- 2021
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14. Highly glycosylated MUC1 mediates high affinity L-selectin binding at the human endometrial surface.
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Francis LW, Yao SN, Powell LC, Griffiths S, Berquand A, Piasecki T, Howe W, Gazze AS, Farach-Carson MC, Constantinou P, Carson D, Margarit L, Gonzalez D, and Conlan RS
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- Biophysics, Cell Adhesion, Cell Line, Epithelial Cells, Glycosylation, Humans, Mucins metabolism, Single Molecule Imaging, L-Selectin chemistry, L-Selectin metabolism, Mucin-1 chemistry, Mucin-1 metabolism
- Abstract
Background: Sialyl-Lewis X/L-selectin high affinity binding interactions between transmembrane O-glycosylated mucins proteins and the embryo have been implicated in implantation processes within the human reproductive system. However, the adhesive properties of these mucins at the endometrial cell surface are difficult to resolve due to known discrepancies between in vivo models and the human reproductive system and a lack of sensitivity in current in vitro models. To overcome these limitations, an in vitro model of the human endometrial epithelial was interrogated with single molecule force spectroscopy (SMFS) to delineate the molecular configurations of mucin proteins that mediate the high affinity L-selectin binding required for human embryo implantation., Results: This study reveals that MUC1 contributes to both the intrinsic and extrinsic adhesive properties of the HEC-1 cellular surface. High expression of MUC1 on the cell surface led to a significantly increased intrinsic adhesion force (148 pN vs. 271 pN, p < 0.001), whereas this adhesion force was significantly reduced (271 pN vs. 118 pN, p < 0.001) following siRNA mediated MUC1 ablation. Whilst high expression of MUC1 displaying elevated glycosylation led to strong extrinsic (> 400 pN) L-selectin binding at the cell surface, low expression of MUC1 with reduced glycosylation resulted in significantly less (≤200 pN) binding events., Conclusions: An optimal level of MUC1 together with highly glycosylated decoration of the protein is critical for high affinity L-selectin binding. This study demonstrates that MUC1 contributes to cellular adhesive properties which may function to facilitate trophoblast binding to the endometrial cell surface through the L-selectin/sialyl-Lewis x adhesion system subsequent to implantation.
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- 2021
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15. Quantifying the effects of antibiotic treatment on the extracellular polymer network of antimicrobial resistant and sensitive biofilms using multiple particle tracking.
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Powell LC, Abdulkarim M, Stokniene J, Yang QE, Walsh TR, Hill KE, Gumbleton M, and Thomas DW
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- Biofilms drug effects, Dose-Response Relationship, Drug, Drug Resistance, Bacterial, Escherichia coli drug effects, Methicillin-Resistant Staphylococcus aureus drug effects, Microbial Sensitivity Tests, Microbial Viability drug effects, Microscopy, Confocal, Nanoparticles, Particle Size, Pseudomonas aeruginosa drug effects, Biofilms growth & development, Escherichia coli physiology, Methicillin-Resistant Staphylococcus aureus physiology, Polymyxin B pharmacology, Pseudomonas aeruginosa physiology, Single Molecule Imaging methods
- Abstract
Novel therapeutics designed to target the polymeric matrix of biofilms requires innovative techniques to accurately assess their efficacy. Here, multiple particle tracking (MPT) was developed to characterize the physical and mechanical properties of antimicrobial resistant (AMR) bacterial biofilms and to quantify the effects of antibiotic treatment. Studies employed nanoparticles (NPs) of varying charge and size (40-500 nm) in Pseudomonas aeruginosa PAO1 and methicillin-resistant Staphylococcus aureus (MRSA) biofilms and also in polymyxin B (PMB) treated Escherichia coli biofilms of PMB-sensitive (PMB
Sens ) IR57 and PMB-resistant (PMBR ) PN47 strains. NP size-dependent and strain-related differences in the diffusion coefficient values of biofilms were evident between PAO1 and MRSA. Dose-dependent treatment effects induced by PMB in PMBSens E. coli biofilms included increases in diffusion and creep compliance (P < 0.05), not evident in PMB treatment of PMBR E. coli biofilms. Our results highlight the ability of MPT to quantify the diffusion and mechanical effects of antibiotic therapies within the AMR biofilm matrix, offering a valuable tool for the pre-clinical screening of anti-biofilm therapies.- Published
- 2021
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16. Phenotypic and Genotypic Adaptations in Pseudomonas aeruginosa Biofilms following Long-Term Exposure to an Alginate Oligomer Therapy.
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Oakley JL, Weiser R, Powell LC, Forton J, Mahenthiralingam E, Rye PD, Hill KE, Thomas DW, and Pritchard MF
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- Anti-Bacterial Agents pharmacology, Biofilms growth & development, Drug Resistance, Multiple, Bacterial, Humans, Microbial Sensitivity Tests, Pseudomonas Infections drug therapy, Pseudomonas aeruginosa genetics, Sputum microbiology, Time Factors, Adaptation, Physiological genetics, Alginates chemistry, Biofilms drug effects, Genotype, Phenotype, Pseudomonas aeruginosa drug effects
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Chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) evolve to generate environmentally adapted biofilm communities, leading to increased patient morbidity and mortality. OligoG CF-5/20, a low-molecular-weight inhaled alginate oligomer therapy, is currently in phase IIb/III clinical trials in CF patients. Experimental evolution of P. aeruginosa in response to OligoG CF-5/20 was assessed using a bead biofilm model allowing continuous passage (45 days; ∼245 generations). Mutants isolated after OligoG CF-5/20 treatment typically had a reduced biofilm-forming ability and altered motility profile. Genotypically, OligoG CF-5/20 provided no selective pressure on genomic mutations within morphotypes. Chronic exposure to azithromycin, a commonly prescribed antibiotic in CF patients, with or without OligoG CF-5/20 in the biofilm evolution model also had no effect on rates of resistance acquisition. Interestingly, however, cross-resistance to other antibiotics (e.g., aztreonam) was reduced in the presence of OligoG CF-5/20. Collectively, these findings show no apparent adverse effects from long-term exposure to OligoG CF-5/20, instead resulting in both fewer colonies with multidrug resistance (MDR)-associated phenotypes and improved antibiotic susceptibility of P. aeruginosa IMPORTANCE The emergence of multidrug-resistant (MDR) pathogens within biofilms in the cystic fibrosis lung results in increased morbidity. An inhalation therapy derived from alginate, OligoG CF-5/20, is currently in clinical trials for cystic fibrosis patients. OligoG CF-5/20 has been shown to alter sputum viscoelasticity, disrupt mucin polymer networks, and disrupt MDR pseudomonal biofilms. Long-term exposure to inhaled therapeutics may induce selective evolutionary pressures on bacteria within the lung biofilm. Here, a bead biofilm model with repeated exposure of P. aeruginosa to OligoG CF-5/20 (alone and in combination with azithromycin) was conducted to study these long-term effects and characterize the phenotypic and genotypic adaptations which result. These findings, over 6 weeks, show that long-term use of OligoG CF-5/20 does not lead to extensive mutational changes and may potentially decrease the pathogenicity of the bacterial biofilm and improve the susceptibility of P. aeruginosa to other classes of antibiotics., (Copyright © 2021 Oakley et al.)
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- 2021
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17. Bi-Functional Alginate Oligosaccharide-Polymyxin Conjugates for Improved Treatment of Multidrug-Resistant Gram-Negative Bacterial Infections.
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Stokniene J, Powell LC, Aarstad OA, Aachmann FL, Rye PD, Hill KE, Thomas DW, and Ferguson EL
- Abstract
The recent emergence of resistance to colistin, an antibiotic of last resort with dose-limiting toxicity, has highlighted the need for alternative approaches to combat infection. This study aimed to generate and characterise alginate oligosaccharide ("OligoG")-polymyxin (polymyxin B and E (colistin)) conjugates to improve the effectiveness of these antibiotics. OligoG-polymyxin conjugates (amide- or ester-linked), with molecular weights of 5200-12,800 g/mol and antibiotic loading of 6.1-12.9% w / w , were reproducibly synthesised. In vitro inflammatory cytokine production (tumour necrosis factor alpha (TNFα) ELISA) and cytotoxicity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) of colistin (2.2-9.3-fold) and polymyxin B (2.9-27.2-fold) were significantly decreased by OligoG conjugation. Antimicrobial susceptibility tests (minimum inhibitory concentration (MIC), growth curves) demonstrated similar antimicrobial efficacy of ester- and amide-linked conjugates to that of the parent antibiotic but with more sustained inhibition of bacterial growth. OligoG-polymyxin conjugates exhibited improved selectivity for Gram-negative bacteria in comparison to mammalian cells (approximately 2-4-fold). Both OligoG-colistin conjugates caused significant disruption of Pseudomonas aeruginosa biofilm formation and induced bacterial death (confocal laser scanning microscopy). When conjugates were tested in an in vitro "time-to-kill" (TTK) model using Acinetobacter baumannii , only ester-linked conjugates reduced viable bacterial counts (~2-fold) after 4 h. Bi-functional OligoG-polymyxin conjugates have potential therapeutic benefits in the treatment of multidrug-resistant (MDR) Gram-negative bacterial infections, directly reducing toxicity whilst retaining antimicrobial and antibiofilm activities.
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- 2020
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18. Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.
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Jack AA, Nordli HR, Powell LC, Farnell DJJ, Pukstad B, Rye PD, Thomas DW, Chinga-Carrasco G, and Hill KE
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- Anti-Bacterial Agents chemistry, Biofilms drug effects, Drug Compounding, Humans, Microbial Sensitivity Tests, Molecular Weight, Oligosaccharides chemistry, Pseudomonas aeruginosa drug effects, Skin drug effects, Staphylococcus aureus drug effects, Alginates chemistry, Anti-Bacterial Agents pharmacology, Biofilms growth & development, Cellulose chemistry, Nanofibers chemistry, Oligosaccharides pharmacology, Wound Healing drug effects
- Abstract
Cellulose nanofibrils (CNFs) from wood pulp are a renewable material possessing advantages for biomedical applications because of their customizable porosity, mechanical strength, translucency, and environmental biodegradability. Here, we investigated the growth of multispecies wound biofilms on CNF formulated as aerogels and films incorporating the low-molecular-weight alginate oligosaccharide OligoG CF-5/20 to evaluate their structural and antimicrobial properties. Overnight microbial cultures were adjusted to 2.8 × 10
9 colony-forming units (cfu) mL-1 in Mueller Hinton broth and growth rates of Pseudomonas aeruginosa PAO1 and Staphylococcus aureus 1061A monitored for 24 h in CNF dispersions sterilized by γ-irradiation. Two CNF formulations were prepared (20 g m-2 ) with CNF as air-dried films or freeze-dried aerogels, with or without incorporation of an antimicrobial alginate oligosaccharide (OligoG CF-5/20) as a surface coating or bionanocomposite, respectively. The materials were structurally characterized by scanning electron microscopy (SEM) and laser profilometry (LP). The antimicrobial properties of the formulations were assessed using single- and mixed-species biofilms grown on the materials and analyzed using LIVE/DEAD staining with confocal laser scanning microscopy (CLSM) and COMSTAT software. OligoG-CNF suspensions significantly decreased the growth of both bacterial strains at OligoG concentrations >2.58% ( P < 0.05). SEM showed that aerogel-OligoG bionanocomposite formulations had a more open three-dimensional structure, whereas LP showed that film formulations coated with OligoG were significantly smoother than untreated films or films incorporating PEG400 as a plasticizer ( P < 0.05). CLSM of biofilms grown on films incorporating OligoG demonstrated altered biofilm architecture, with reduced biomass and decreased cell viability. The OligoG-CNF formulations as aerogels or films both inhibited pyocyanin production ( P < 0.05). These novel CNF formulations or bionanocomposites were able to modify bacterial growth, biofilm development, and virulence factor production in vitro. These data support the potential of OligoG and CNF bionanocomposites for use in biomedical applications where prevention of infection or biofilm growth is required.- Published
- 2019
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19. Polymer Masked-Unmasked Protein Therapy: Identification of the Active Species after Amylase Activation of Dextrin-Colistin Conjugates.
- Author
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Varache M, Powell LC, Aarstad OA, Williams TL, Wenzel MN, Thomas DW, and Ferguson EL
- Subjects
- Anti-Bacterial Agents chemistry, Anti-Bacterial Agents metabolism, Biofilms drug effects, Cell Line, Cell Survival drug effects, Chromatography, Gel, Escherichia coli drug effects, Humans, Kidney Tubules, Proximal cytology, Mass Spectrometry, Microbial Sensitivity Tests, Microscopy, Confocal, Molecular Structure, Amylases metabolism, Colistin chemistry, Colistin metabolism, Dextrins chemistry, Dextrins metabolism, Drug Compounding methods, Drug Delivery Systems methods
- Abstract
Polymer masked-unmasked protein therapy (PUMPT) uses conjugation of a biodegradable polymer, such as dextrin, hyaluronic acid, or poly(l-glutamic acid), to mask a protein or peptide's activity; subsequent locally triggered degradation of the polymer at the target site regenerates bioactivity in a controllable fashion. Although the concept of PUMPT is well established, the relationship between protein unmasking and reinstatement of bioactivity is unclear. Here, we used dextrin-colistin conjugates to study the relationship between the molecular structure (degree of unmasking) and biological activity. Size exclusion chromatography was employed to collect fractions of differentially degraded conjugates and ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) employed to characterize the corresponding structures. Antimicrobial activity was studied using a minimum inhibitory concentration (MIC) assay and confocal laser scanning microscopy of LIVE/DEAD-stained biofilms with COMSTAT analysis. In vitro toxicity of the degraded conjugate was assessed using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. UPLC-MS revealed that the fully "unmasked" dextrin-colistin conjugate composed of colistin bound to at least one linker, whereas larger species were composed of colistin with varying lengths of glucose units attached. Increasing the degree of dextrin modification by succinoylation typically led to a greater number of linkers bound to colistin. Greater antimicrobial and antibiofilm activity were observed for the fully "unmasked" conjugate compared to the partially degraded species (MIC = 0.25 and 2-8 μg/mL, respectively), whereas dextrin conjugation reduced colistin's in vitro toxicity toward kidney cells, even after complete unmasking. This study highlights the importance of defining the structure-antimicrobial activity relationship for novel antibiotic derivatives and demonstrates the suitability of LC-MS to aid the design of biodegradable polymer-antibiotic conjugates.
- Published
- 2019
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20. Frequency and age at occurrence of clinical manifestations of disease in patients with hypophosphatasia: a systematic literature review.
- Author
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Szabo SM, Tomazos IC, Petryk A, Powell LC, Donato BMK, Zarate YA, Tiulpakov A, and Martos-Moreno GÁ
- Subjects
- Adolescent, Adult, Alkaline Phosphatase genetics, Child, Child, Preschool, Enzyme Replacement Therapy, Female, Fractures, Bone epidemiology, Fractures, Bone genetics, Humans, Hypophosphatasia complications, Hypophosphatasia genetics, Infant, Infant, Newborn, Male, Pain epidemiology, Pain etiology, Young Adult, Hypophosphatasia epidemiology, Hypophosphatasia pathology
- Abstract
Background: Hypophosphatasia (HPP) is a rare, inherited, metabolic disease caused by tissue-nonspecific alkaline phosphatase deficiency, characterized by bone mineralization defects and systemic complications. Understanding of the clinical course and burden of HPP is limited by its rarity. This systematic literature review and synthesis of case report data aimed to determine the frequency and timing of clinical HPP manifestations and events., Methods: Case reports and series of patients with HPP who had been followed longitudinally for ≥1 year were identified. Demographics and clinical data of interest, identified through consultation with clinical experts in HPP, were extracted. Occurrences of clinical manifestations/events of interest were categorized, classified by age at first reported occurrence of HPP manifestations and visualized over time. Clinical manifestations/events considered to contribute to the clinical burden of HPP were identified. Kaplan-Meier curves were used to estimate the median (range) age at first occurrence of the most frequently reported manifestations/events., Results: From the 283 studies that met the inclusion criteria, 265 patients with HPP with ≥1 year of longitudinal follow-up were identified (median [interquartile range] age 4 [0-34] years; 45% male). The types of clinical manifestations/events of interest experienced by individuals with ≥1 such manifestation/event (n = 261) often differed between older and younger patients. Most (94%) of the 265 patients experienced ≥1 manifestation/event deemed to contribute to the clinical burden of HPP; premature tooth loss (53.5%), fractures (35.8%), pain (33.6%), and gross motor/ambulation difficulties (30.9%) were most frequently reported. The median (range) age at first reported occurrence of respiratory symptoms, cranial abnormalities, and premature tooth loss ranged from 0.3 to 10 years, whereas the median age at first reported occurrence of fractures, pain, gross motor/ambulation difficulties, and surgery ranged from 33 to 70 years., Conclusions: HPP is associated with a high clinical burden of disease, regardless of age at first reported occurrence of HPP manifestations. Over an individual's lifetime, the types of manifestations/events experienced can change and multiple HPP-related clinical manifestations/events can accumulate. These observations may reflect evolution and progression of the disease.
- Published
- 2019
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21. Anti-pseudomonad Activity of Manuka Honey and Antibiotics in a Specialized ex vivo Model Simulating Cystic Fibrosis Lung Infection.
- Author
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Roberts AEL, Powell LC, Pritchard MF, Thomas DW, and Jenkins RE
- Abstract
Pseudomonas aeruginosa causes problematic chronic lung infections in those suffering from cystic fibrosis. This is due to its antimicrobial resistance mechanisms and its ability to form robust biofilm communities with increased antimicrobial tolerances. Using novel antimicrobials or repurposing current ones is required in order to overcome these problems. Manuka honey is a natural antimicrobial agent that has been used for many decades in the treatment of chronic surface wounds with great success, particularly those infected with P. aeruginosa . Here we aim to determine whether the antimicrobial activity of manuka honey could potentially be repurposed to inhibit pulmonary P. aeruginosa infections using two ex vivo models. P. aeruginosa isolates ( n = 28) from an international panel were tested for their susceptibility to manuka honey and clinically relevant antibiotics (ciprofloxacin, ceftazidime, and tobramycin), alone and in combination, using conventional antimicrobial susceptibility testing (AST). To increase clinical applicability, two ex vivo porcine lung (EVPL) models (using alveolar and bronchiolar tissue) were used to determine the anti-biofilm effects of manuka honey alone and in combination with antibiotics. All P. aeruginosa isolates were susceptible to manuka honey, however, varying incidences of resistance were seen against antibiotics. The combination of sub-inhibitory manuka honey and antibiotics using conventional AST had no effect on activity against the majority of isolates tested. Using the two ex vivo models, 64% (w/v) manuka honey inhibited many of the isolates where abnormally high concentrations of antibiotics could not. Typically, combinations of both manuka honey and antibiotics had increased antimicrobial activity. These results highlight the potential of manuka honey as a future antimicrobial for the treatment of pulmonary P. aeruginosa isolates, clearing potential infection reservoirs within the upper airway.
- Published
- 2019
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22. The burden of treatment-resistant depression: A systematic review of the economic and quality of life literature.
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Johnston KM, Powell LC, Anderson IM, Szabo S, and Cline S
- Subjects
- Depressive Disorder, Treatment-Resistant epidemiology, Female, Health Status, Humans, Male, Quality of Life, Cost of Illness, Depressive Disorder, Treatment-Resistant economics, Health Care Costs trends
- Abstract
Background: Major depressive disorder (MDD) is a global public health concern. In particular, treatment-resistant depression (TRD) represents a key unmet need in the management of MDD. A systematic review of the epidemiological and economic literature on the burden associated with an increasing number of treatment steps due to TRD/non-response within an MDD episode was performed to quantify the burden of TRD., Methods: Studies were identified in the PubMed/Medline databases through April 27th, 2017. Articles were limited to full-length peer-reviewed journal publications with no date restrictions. Economic and patient health-related quality of life (HRQoL) data on non-response by the number of treatment steps were quantified and, where appropriate, compared across studies; otherwise, comparative data within studies were reported., Results: The 12 studies on economic burden found an association between increasing levels of TRD/non-response and elevations in direct and indirect costs. Likewise, the 19 studies studying HRQoL burden found that increasing levels of TRD/non-response correlated with reduced patient HRQoL and health status., Limitations: TRD is defined inconsistently, which results in notable heterogeneity between published studies and poses methodological challenges for between-study comparisons. It is unknown if the increased economic and patient HRQoL burden are due to factors associated with TRD/non-response in addition to those due to depression persistence or severity., Conclusions: A consistent trend was observed such that medical costs increased and patient HRQoL and health status decreased by increasing level of TRD/non-response within an MDD episode. These findings highlight the need for improved therapies for TRD to help reduce disease burden., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2019
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23. Controlled release of dextrin-conjugated growth factors to support growth and differentiation of neural stem cells.
- Author
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Ferguson EL, Naseer S, Powell LC, Hardwicke J, Young FI, Zhu B, Liu Q, Song B, and Thomas DW
- Subjects
- Cell Differentiation, Cell Proliferation, Humans, Cell Culture Techniques methods, Dextrins metabolism, Fibroblast Growth Factor 2 metabolism, Neural Stem Cells metabolism
- Abstract
An essential aspect of stem cell in vitro culture and in vivo therapy is achieving sustained levels of growth factors to support stem cell survival and expansion, while maintaining their multipotency and differentiation potential. This study investigated the ability of dextrin (~74,000 g/mol; 27.8 mol% succinoylation) conjugated to epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF; or FGF-2) (3.9 and 6.7% w/w protein loading, respectively) to support the expansion and differentiation of stem cells in vitro via sustained, controllable growth factor release. Supplementation of mouse neural stem cells (mNSCs) with dextrin-growth factor conjugates led to greater and prolonged proliferation compared to unbound EGF/bFGF controls, with no detectable apoptosis after 7 days of treatment. Immunocytochemical detection of neural precursor (nestin) and differentiation (Olig2, MAP2, GFAP) markers verified that controlled release of dextrin-conjugated growth factors preserves stem cell properties of mNSCs for up to 7 days. These results show the potential of dextrin-growth factor conjugates for localized delivery of bioactive therapeutic agents to support stem cell expansion and differentiation, and as an adjunct to direct neuronal repair., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2018
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24. Targeted disruption of the extracellular polymeric network of Pseudomonas aeruginosa biofilms by alginate oligosaccharides.
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Powell LC, Pritchard MF, Ferguson EL, Powell KA, Patel SU, Rye PD, Sakellakou SM, Buurma NJ, Brilliant CD, Copping JM, Menzies GE, Lewis PD, Hill KE, and Thomas DW
- Abstract
Acquisition of a mucoid phenotype by Pseudomonas sp. in the lungs of cystic fibrosis (CF) patients, with subsequent over-production of extracellular polymeric substance (EPS), plays an important role in mediating the persistence of multi-drug resistant (MDR) infections. The ability of a low molecular weight (Mn = 3200 g mol
-1 ) alginate oligomer (OligoG CF-5/20) to modify biofilm structure of mucoid Pseudomonas aeruginosa (NH57388A) was studied in vitro using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) with Texas Red (TxRd®)-labelled OligoG and EPS histochemical staining. Structural changes in treated biofilms were quantified using COMSTAT image-analysis software of CLSM z-stack images, and nanoparticle diffusion. Interactions between the oligomers, Ca2+ and DNA were studied using molecular dynamics (MD) simulations, Fourier transform infrared spectroscopy (FTIR) and isothermal titration calorimetry (ITC). Imaging demonstrated that OligoG treatment (≥0.5%) inhibited biofilm formation, revealing a significant reduction in both biomass and biofilm height ( P < 0.05). TxRd®-labelled oligomers readily diffused into established (24 h) biofilms. OligoG treatment (≥2%) induced alterations in the EPS of established biofilms; significantly reducing the structural quantities of EPS polysaccharides, and extracellular (e)DNA ( P < 0.05) with a corresponding increase in nanoparticle diffusion ( P < 0.05) and antibiotic efficacy against established biofilms. ITC demonstrated an absence of rapid complex formation between DNA and OligoG and confirmed the interactions of OligoG with Ca2+ evident in FTIR and MD modelling. The ability of OligoG to diffuse into biofilms, potentiate antibiotic activity, disrupt DNA-Ca2+ -DNA bridges and biofilm EPS matrix highlights its potential for the treatment of biofilm-related infections., Competing Interests: D.W.T. has a consultancy relationship and has, with K.E.H., received research funding from AlgiPharma AS. P.D.R. is a director/owner of AlgiPharma AS. The remaining authors declare no competing interests.- Published
- 2018
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25. Alginate Oligosaccharide-Induced Modification of the lasI-lasR and rhlI-rhlR Quorum-Sensing Systems in Pseudomonas aeruginosa.
- Author
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Jack AA, Khan S, Powell LC, Pritchard MF, Beck K, Sadh H, Sutton L, Cavaliere A, Florance H, Rye PD, Thomas DW, and Hill KE
- Subjects
- 4-Butyrolactone analogs & derivatives, 4-Butyrolactone metabolism, Pseudomonas aeruginosa metabolism, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Pseudomonas aeruginosa drug effects, Quorum Sensing drug effects
- Abstract
Pseudomonas aeruginosa plays a major role in many chronic infections. Its ability to readily form biofilms contributes to its success as an opportunistic pathogen and its resistance/tolerance to antimicrobial/antibiotic therapy. A low-molecular-weight alginate oligomer (OligoG CF-5/20) derived from marine algae has previously been shown to impair motility in P. aeruginosa biofilms and disrupt pseudomonal biofilm assembly. As these bacterial phenotypes are regulated by quorum sensing (QS), we hypothesized that OligoG CF-5/20 may induce alterations in QS signaling in P. aeruginosa QS regulation was studied by using Chromobacterium violaceum CV026 biosensor assays that showed a significant reduction in acyl homoserine lactone (AHL) production following OligoG CF-5/20 treatment (≥2%; P < 0.05). This effect was confirmed by liquid chromatography-mass spectrometry analysis of C
4 -AHL and 3-oxo-C12 -AHL production (≥2%; P < 0.05). Moreover, quantitative PCR showed that reduced expression of both the las and rhl systems was induced following 24 h of treatment with OligoG CF-5/20 (≥0.2%; P < 0.05). Circular dichroism spectroscopy indicated that these alterations were not due to steric interaction between the AHL and OligoG CF-5/20. Confocal laser scanning microscopy (CLSM) and COMSTAT image analysis demonstrated that OligoG CF-5/20-treated biofilms had a dose-dependent decrease in biomass that was associated with inhibition of extracellular DNA synthesis (≥0.5%; P < 0.05). These changes correlated with alterations in the extracellular production of the pseudomonal virulence factors pyocyanin, rhamnolipids, elastase, and total protease ( P < 0.05). The ability of OligoG CF-5/20 to modify QS signaling in P. aeruginosa PAO1 may influence critical downstream functions such as virulence factor production and biofilm formation., (Copyright © 2018 American Society for Microbiology.)- Published
- 2018
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26. The economic burden of overactive bladder in the United States: A systematic literature review.
- Author
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Powell LC, Szabo SM, Walker D, and Gooch K
- Subjects
- Depression, Humans, United States, Cost of Illness, Health Care Costs, Urinary Bladder, Overactive economics
- Abstract
Aims: Overactive bladder (OAB) affects up to 17% of the United States (US) population. This study aimed to synthesize estimates of direct and indirect costs of OAB in the US and compare costs among those with and without OAB., Methods: A systematic review was performed using MEDLINE/PubMed and Embase, from 2003 to 2016, following PRISMA guidelines. The target population was adults with idiopathic OAB or urge urinary incontinence from the US. Data were extracted on study and patient characteristics, all-cause and OAB-specific direct costs, resource use, and indirect costs. Costs were inflated to a common price year of 2016 USD., Results: Eighteen studies were included. Mean insurer paid all-cause total direct healthcare costs ranged from 8168 to 15 569 USD, and OAB-specific costs ranged from 656 to 860 USD per-patient annually. Estimates of the incremental costs for OAB patients compared to non-OAB comparators ranged from 43% to 117%. One study estimated total annual indirect costs of OAB at 11 134 USD per-patient., Conclusions: The range of direct healthcare costs reported for managing patients with OAB varied, but was relatively small given the differing contributing data sources, study designs, and cost definitions. Direct costs were consistently higher among patients with OAB versus non-OAB comparisons, from a 1.4- to >2-fold increase annually. OAB-specific costs made up a small proportion of all-cause costs, highlighting the clinical and economic impact of OAB-related conditions such as falls, urinary tract infection, and depression. Few studies were identified that examined the indirect costs of OAB in the US., (© 2018 Wiley Periodicals, Inc.)
- Published
- 2018
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27. Alginate oligosaccharides modify hyphal infiltration of Candida albicans in an in vitro model of invasive human candidosis.
- Author
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Pritchard MF, Jack AA, Powell LC, Sadh H, Rye PD, Hill KE, and Thomas DW
- Subjects
- Candida albicans genetics, Candida albicans growth & development, Candida albicans metabolism, Candidiasis drug therapy, Glucuronic Acid pharmacology, Hexuronic Acids pharmacology, Humans, Hyphae drug effects, Hyphae growth & development, Virulence Factors genetics, Virulence Factors metabolism, Alginates pharmacology, Antifungal Agents pharmacology, Candida albicans drug effects, Candidiasis microbiology, Oligosaccharides pharmacology
- Abstract
Aims: A novel alginate oligomer (OligoG CF-5/20) has been shown to potentiate antifungal therapy against a range of fungal pathogens. The current study assessed the effect of this oligomer on in vitro virulence factor expression and epithelial invasion by Candida species., Methods and Results: Plate substrate assays and epithelial models were used to assess Candida albicans (CCUG 39343 and ATCC 90028) invasion, in conjunction with confocal laser scanning microscopy and histochemistry. Expression of candidal virulence factors was determined biochemically and by quantitative PCR (qPCR). Changes in surface charge of C. albicans following OligoG treatment were analysed using electrophoretic light scattering. OligoG induced marked alterations in hyphal formation in the substrate assays and reduced invasion in the epithelial model (P < 0·001). Significant dose-dependent inhibition of phospholipase activity in C. albicans was evident following OligoG treatment (P < 0·05). While OligoG binding failed to affect alterations in surface charge (P > 0·05), qPCR demonstrated a reduction in phospholipase B (PLB2) and SAPs (SAP4 and SAP6) expression., Conclusion: OligoG CF-5/20 reduced in vitro virulence factor expression and invasion by C. albicans., Significance and Impact of the Study: These results, and the previously described potentiation of antifungal activity, define a potential therapeutic opportunity in the treatment of invasive candidal infections., (© 2017 The Society for Applied Microbiology.)
- Published
- 2017
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28. A Low-Molecular-Weight Alginate Oligosaccharide Disrupts Pseudomonal Microcolony Formation and Enhances Antibiotic Effectiveness.
- Author
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Pritchard MF, Powell LC, Jack AA, Powell K, Beck K, Florance H, Forton J, Rye PD, Dessen A, Hill KE, and Thomas DW
- Subjects
- Biofilms drug effects, Cystic Fibrosis microbiology, Drug Resistance, Multiple, Bacterial, Drug Synergism, Glucuronic Acid pharmacology, Hexuronic Acids pharmacology, Humans, Microbial Sensitivity Tests, Pseudomonas Infections microbiology, Pseudomonas aeruginosa growth & development, Quorum Sensing drug effects, Respiratory Tract Infections microbiology, Sputum microbiology, Alginates pharmacology, Anti-Bacterial Agents pharmacology, Biofilms growth & development, Colistin pharmacology, Oligosaccharides pharmacology, Pseudomonas Infections drug therapy, Pseudomonas aeruginosa drug effects, Respiratory Tract Infections drug therapy
- Abstract
In chronic respiratory disease, the formation of dense, 3-dimensional "microcolonies" by Pseudomonas aeruginosa within the airway plays an important role in contributing to resistance to treatment. An in vitro biofilm model of pseudomonal microcolony formation using artificial-sputum (AS) medium was established to study the effects of low-molecular-weight alginate oligomers (OligoG CF-5/20) on pseudomonal growth, microcolony formation, and the efficacy of colistin. The studies employed clinical cystic fibrosis (CF) isolates ( n = 3) and reference nonmucoid and mucoid multidrug-resistant (MDR) CF isolates ( n = 7). Bacterial growth and biofilm development and disruption were studied using cell viability assays and image analysis with scanning electron and confocal laser scanning microscopy. Pseudomonal growth in AS medium was associated with increased ATP production ( P < 0.05) and the formation (at 48 h) of discrete (>10-μm) microcolonies. In conventional growth medium, colistin retained an ability to inhibit growth of planktonic bacteria, although the MIC was increased (0.1 to 0.4 μg/ml) in AS medium compared to Mueller-Hinton (MH) medium. In contrast, in an established-biofilm model in AS medium, the efficacy of colistin was decreased. OligoG CF-5/20 (≥2%) treatment, however, induced dose-dependent biofilm disruption ( P < 0.05) and led to colistin retaining its antimicrobial activity ( P < 0.05). While circular dichroism indicated that OligoG CF-5/20 did not change the orientation of the alginate carboxyl groups, mass spectrometry demonstrated that the oligomers induced dose-dependent (>0.2%; P < 0.05) reductions in pseudomonal quorum-sensing signaling. These findings reinforce the potential clinical significance of microcolony formation in the CF lung and highlight a novel approach to treat MDR pseudomonal infections., (Copyright © 2017 American Society for Microbiology.)
- Published
- 2017
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29. The antimicrobial effects of the alginate oligomer OligoG CF-5/20 are independent of direct bacterial cell membrane disruption.
- Author
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Pritchard MF, Powell LC, Khan S, Griffiths PC, Mansour OT, Schweins R, Beck K, Buurma NJ, Dempsey CE, Wright CJ, Rye PD, Hill KE, Thomas DW, and Ferguson EL
- Subjects
- Alginates chemistry, Cations, Divalent pharmacology, Cell Membrane drug effects, Cell Membrane Permeability drug effects, Cell Wall drug effects, Cell Wall metabolism, Glucuronic Acid chemistry, Glucuronic Acid pharmacology, Hexuronic Acids chemistry, Hexuronic Acids pharmacology, Lipopolysaccharides chemistry, Lipopolysaccharides pharmacology, Microbial Sensitivity Tests, Pseudomonas aeruginosa drug effects, Streptococcus mutans drug effects, Alginates pharmacology, Anti-Infective Agents pharmacology, Cell Membrane metabolism, Pseudomonas aeruginosa cytology, Streptococcus mutans cytology
- Abstract
Concerns about acquisition of antibiotic resistance have led to increasing demand for new antimicrobial therapies. OligoG CF-5/20 is an alginate oligosaccharide previously shown to have antimicrobial and antibiotic potentiating activity. We investigated the structural modification of the bacterial cell wall by OligoG CF-5/20 and its effect on membrane permeability. Binding of OligoG CF-5/20 to the bacterial cell surface was demonstrated in Gram-negative bacteria. Permeability assays revealed that OligoG CF-5/20 had virtually no membrane-perturbing effects. Lipopolysaccharide (LPS) surface charge and aggregation were unaltered in the presence of OligoG CF-5/20. Small angle neutron scattering and circular dichroism spectroscopy showed no substantial change to the structure of LPS in the presence of OligoG CF-5/20, however, isothermal titration calorimetry demonstrated a weak calcium-mediated interaction. Metabolomic analysis confirmed no change in cellular metabolic response to a range of osmolytes when treated with OligoG CF-5/20. This data shows that, although weak interactions occur between LPS and OligoG CF-5/20 in the presence of calcium, the antimicrobial effects of OligoG CF-5/20 are not related to the induction of structural alterations in the LPS or cell permeability. These results suggest a novel mechanism of action that may avoid the common route in acquisition of resistance via LPS structural modification.
- Published
- 2017
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30. The interaction of wood nanocellulose dressings and the wound pathogen P. aeruginosa.
- Author
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Jack AA, Nordli HR, Powell LC, Powell KA, Kishnani H, Johnsen PO, Pukstad B, Thomas DW, Chinga-Carrasco G, and Hill KE
- Subjects
- Biofilms, Pseudomonas aeruginosa growth & development, Bandages, Cellulose chemistry, Nanoparticles, Wood
- Abstract
Chronic wounds pose an increasingly significant worldwide economic burden (over £1 billion per annum in the UK alone). With the escalation in global obesity and diabetes, chronic wounds will increasingly be a significant cause of morbidity and mortality. Cellulose nanofibrils (CNF) are highly versatile and can be tailored with specific physical properties to produce an assortment of three-dimensional structures (hydrogels, aerogels or films), for subsequent utilization as wound dressing materials. Growth curves using CNF (diameter <20nm) in suspension demonstrated an interesting dose-dependent inhibition of bacterial growth. In addition, analysis of biofilm formation (Pseudomonas aeruginosa PAO1) on nanocellulose aerogels (20g/m
2 ) revealed significantly less biofilm biomass with decreasing aerogel porosity and surface roughness. Importantly, virulence factor production by P. aeruginosa in the presence of nanocellulose materials, quantified for the first time, was unaffected (p>0.05) over 24h. These data demonstrate the potential of nanocellulose materials in the development of novel dressings that may afford significant clinical potential., (Copyright © 2016 Elsevier Ltd. All rights reserved.)- Published
- 2017
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31. A New Class of Safe Oligosaccharide Polymer Therapy To Modify the Mucus Barrier of Chronic Respiratory Disease.
- Author
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Pritchard MF, Powell LC, Menzies GE, Lewis PD, Hawkins K, Wright C, Doull I, Walsh TR, Onsøyen E, Dessen A, Myrvold R, Rye PD, Myrset AH, Stevens HN, Hodges LA, MacGregor G, Neilly JB, Hill KE, and Thomas DW
- Subjects
- Adolescent, Adult, Alginates metabolism, Animals, Chronic Disease, Clinical Trials, Phase I as Topic, Female, Glucuronic Acid chemistry, Glucuronic Acid metabolism, Hexuronic Acids chemistry, Hexuronic Acids metabolism, Humans, Male, Microscopy, Atomic Force, Microscopy, Electron, Scanning, Mucins metabolism, Mucus metabolism, Oligosaccharides metabolism, Polymers chemistry, Rats, Rats, Sprague-Dawley, Rheology, Spectroscopy, Fourier Transform Infrared, Sputum chemistry, Swine, Young Adult, Alginates chemistry, Cystic Fibrosis drug therapy, Mucins chemistry, Mucus chemistry, Oligosaccharides chemistry, Polymers pharmacology
- Abstract
The host- and bacteria-derived extracellular polysaccharide coating of the lung is a considerable challenge in chronic respiratory disease and is a powerful barrier to effective drug delivery. A low molecular weight 12-15-mer alginate oligosaccharide (OligoG CF-5/20), derived from plant biopolymers, was shown to modulate the polyanionic components of this coating. Molecular modeling and Fourier transform infrared spectroscopy demonstrated binding between OligoG CF-5/20 and respiratory mucins. Ex vivo studies showed binding induced alterations in mucin surface charge and porosity of the three-dimensional mucin networks in cystic fibrosis (CF) sputum. Human studies showed that OligoG CF-5/20 is safe for inhalation in CF patients with effective lung deposition and modifies the viscoelasticity of CF-sputum. OligoG CF-5/20 is the first inhaled polymer therapy, represents a novel mechanism of action and therapeutic approach for the treatment of chronic respiratory disease, and is currently in Phase IIb clinical trials for the treatment of CF.
- Published
- 2016
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32. An investigation of Pseudomonas aeruginosa biofilm growth on novel nanocellulose fibre dressings.
- Author
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Powell LC, Khan S, Chinga-Carrasco G, Wright CJ, Hill KE, and Thomas DW
- Subjects
- Microscopy, Atomic Force, Biofilms growth & development, Cellulose chemistry, Nanostructures chemistry, Pseudomonas aeruginosa growth & development
- Abstract
Nanocellulose from wood is a novel biomaterial, which is highly fibrillated at the nanoscale. This affords the material a number of advantages, including self-assembly, biodegradability and the ability to absorb and retain moisture, which highlights its potential usefulness in clinical wound-dressing applications. In these in vitro studies, the wound pathogen Pseudomonas aeruginosa PAO1 was used to assess the ability of two nanocellulose materials to impair bacterial growth (<48 h). The two nanocelluloses had a relatively small fraction of residual fibres (<4%) and thus a large fraction of nanofibrils (widths <20 nm). Scanning electron microscopy and confocal laser scanning microscopy imaging demonstrated impaired biofilm growth on the nanocellulose films and increased cell death when compared to a commercial control wound dressing, Aquacel(®). Nanocellulose suspensions inhibited bacterial growth, whilst UV-vis spectrophotometry and laser profilometry also revealed the ability of nanocellulose to form smooth, translucent films. Atomic force microscopy studies of the surface properties of nanocellulose demonstrated that PAO1 exhibited markedly contrasting morphology when grown on the nanocellulose film surfaces compared to an Aquacel(®) control dressing (p<0.05). This study highlights the potential utility of these biodegradable materials, from a renewable source, for wound dressing applications in the prevention and treatment of biofilm development., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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33. 3D Bioprinting of Carboxymethylated-Periodate Oxidized Nanocellulose Constructs for Wound Dressing Applications.
- Author
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Rees A, Powell LC, Chinga-Carrasco G, Gethin DT, Syverud K, Hill KE, and Thomas DW
- Subjects
- Bandages, Cellulose chemistry, Humans, Materials Testing, Nanostructures chemistry, Periodic Acid chemistry, Periodic Acid therapeutic use, Printing, Three-Dimensional, Pseudomonas aeruginosa drug effects, Pseudomonas aeruginosa pathogenicity, Bioprinting, Cellulose therapeutic use, Nanostructures therapeutic use, Wound Healing drug effects
- Abstract
Nanocellulose has a variety of advantages, which make the material most suitable for use in biomedical devices such as wound dressings. The material is strong, allows for production of transparent films, provides a moist wound healing environment, and can form elastic gels with bioresponsive characteristics. In this study, we explore the application of nanocellulose as a bioink for modifying film surfaces by a bioprinting process. Two different nanocelluloses were used, prepared with TEMPO mediated oxidation and a combination of carboxymethylation and periodate oxidation. The combination of carboxymethylation and periodate oxidation produced a homogeneous material with short nanofibrils, having widths <20 nm and lengths <200 nm. The small dimensions of the nanofibrils reduced the viscosity of the nanocellulose, thus yielding a material with good rheological properties for use as a bioink. The nanocellulose bioink was thus used for printing 3D porous structures, which is exemplified in this study. We also demonstrated that both nanocelluloses did not support bacterial growth, which is an interesting property of these novel materials.
- Published
- 2015
- Full Text
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34. Alginate oligosaccharides inhibit fungal cell growth and potentiate the activity of antifungals against Candida and Aspergillus spp.
- Author
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Tøndervik A, Sletta H, Klinkenberg G, Emanuel C, Powell LC, Pritchard MF, Khan S, Craine KM, Onsøyen E, Rye PD, Wright C, Thomas DW, and Hill KE
- Subjects
- Alginates chemistry, Cell Proliferation drug effects, Dimerization, Drug Synergism, Glucuronic Acid chemistry, Glucuronic Acid pharmacology, Hexuronic Acids chemistry, Hexuronic Acids pharmacology, Microbial Sensitivity Tests, Alginates pharmacology, Antifungal Agents pharmacology, Aspergillus cytology, Aspergillus drug effects, Candida cytology, Candida drug effects, Oligosaccharides chemistry
- Abstract
The oligosaccharide OligoG, an alginate derived from seaweed, has been shown to have anti-bacterial and anti-biofilm properties and potentiates the activity of selected antibiotics against multi-drug resistant bacteria. The ability of OligoG to perturb fungal growth and potentiate conventional antifungal agents was evaluated using a range of pathogenic fungal strains. Candida (n = 11) and Aspergillus (n = 3) spp. were tested using germ tube assays, LIVE/DEAD staining, scanning electron microscopy (SEM), atomic force microscopy (AFM) and high-throughput minimum inhibition concentration assays (MICs). In general, the strains tested showed a significant dose-dependent reduction in cell growth at ≥6% OligoG as measured by optical density (OD600; P<0.05). OligoG (>0.5%) also showed a significant inhibitory effect on hyphal growth in germ tube assays, although strain-dependent variations in efficacy were observed (P<0.05). SEM and AFM both showed that OligoG (≥2%) markedly disrupted fungal biofilm formation, both alone, and in combination with fluconazole. Cell surface roughness was also significantly increased by the combination treatment (P<0.001). High-throughput robotic MIC screening demonstrated the potentiating effects of OligoG (2, 6, 10%) with nystatin, amphotericin B, fluconazole, miconazole, voriconazole or terbinafine with the test strains. Potentiating effects were observed for the Aspergillus strains with all six antifungal agents, with an up to 16-fold (nystatin) reduction in MIC. Similarly, all the Candida spp. showed potentiation with nystatin (up to 16-fold) and fluconazole (up to 8-fold). These findings demonstrate the antifungal properties of OligoG and suggest a potential role in the management of fungal infections and possible reduction of antifungal toxicity.
- Published
- 2014
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- View/download PDF
35. A nanoscale characterization of the interaction of a novel alginate oligomer with the cell surface and motility of Pseudomonas aeruginosa.
- Author
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Powell LC, Pritchard MF, Emanuel C, Onsøyen E, Rye PD, Wright CJ, Hill KE, and Thomas DW
- Subjects
- Alginates chemistry, Anti-Bacterial Agents chemistry, Burkholderia drug effects, Burkholderia growth & development, Chemistry, Pharmaceutical, Dose-Response Relationship, Drug, Glucuronic Acid chemistry, Glucuronic Acid pharmacology, Hexuronic Acids chemistry, Hexuronic Acids pharmacology, Light, Microscopy, Atomic Force, Nanoparticles, Pseudomonas aeruginosa physiology, Scattering, Radiation, Surface Properties, Alginates pharmacology, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Nanomedicine methods, Pseudomonas aeruginosa drug effects
- Abstract
Pseudomonas aeruginosa (PA) biofilm-associated infections are a common cause of morbidity in chronic respiratory disease and represent a therapeutic challenge. Recently, the ability of a novel alginate oligomer (OligoG) to potentiate the effect of antibiotics against gram-negative, multi-drug-resistant bacteria and inhibit biofilm formation in vitro has been described. Interaction of OligoG with the cell surface of PA was characterized at the nanoscale using atomic force microscopy (AFM), zeta potential measurement (surface charge), and sizing measurements (dynamic light scattering). The ability of OligoG to modify motility was studied in motility assays. AFM demonstrated binding of OligoG to the bacterial cell surface, which was irreversible after exposure to hydrodynamic shear (5,500 × g). Zeta potential analysis (pH 5-9; 0.1-0.001 M NaCl) demonstrated that binding was associated with marked changes in the bacterial surface charge (-30.9 ± 0.8 to -47.0 ± 2.3 mV; 0.01 M NaCl [pH 5]; P < 0.001). Sizing analysis demonstrated that alteration of surface charge was associated with cell aggregation with a 2- to 3-fold increase in mean particle size at OligoG concentrations greater than 2% (914 ± 284 to 2599 ± 472 nm; 0.01 M NaCl [pH 5]; P < 0.001). These changes were associated with marked dose-dependent inhibition in bacterial swarming motility in PA and Burkholderia spp. The ability of OligoG to bind to a bacterial surface, modulate surface charge, induce microbial aggregation, and inhibit motility represents important direct mechanisms by which antibiotic potentiation and biofilm disruption is affected. These results highlight the value of combining multiple nanoscale technologies to further our understanding of the mechanisms of action of novel antibacterial therapies.
- Published
- 2014
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- View/download PDF
36. An in vitro study of alginate oligomer therapies on oral biofilms.
- Author
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Roberts JL, Khan S, Emanuel C, Powell LC, Pritchard MF, Onsøyen E, Myrvold R, Thomas DW, and Hill KE
- Subjects
- Bacterial Adhesion drug effects, Bacterial Load drug effects, Bacteriological Techniques, Dental Materials chemistry, Drug Combinations, Drug Synergism, Humans, Materials Testing, Microbial Viability drug effects, Microscopy, Atomic Force, Microscopy, Fluorescence, Polymethyl Methacrylate chemistry, Porphyromonas gingivalis drug effects, Saliva, Artificial chemistry, Streptococcus mutans drug effects, Titanium chemistry, Triclosan pharmacology, Alginates pharmacology, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Mouth microbiology, Oligosaccharides pharmacology
- Abstract
Objectives: The in vitro effect of a novel, oligosaccharide nanomedicine OligoG against oral pathogen-related biofilms, both alone and in the presence of the conventional anti-bacterial agent triclosan, was evaluated., Methods: The effect of OligoG±triclosan was assessed against established Streptococcus mutans and Porphyromonas gingivalis biofilms by bacterial counts and image analysis using LIVE/DEAD(®) staining and atomic force microscopy (AFM). The effect of triclosan and OligoG surface pre-treatments on bacterial attachment to titanium and polymethylmethacrylate was also studied., Results: OligoG potentiated the antimicrobial effect of triclosan, particularly when used in combination at 0.3% against S. mutans grown in artificial saliva. OligoG was less effective against established P. gingivalis biofilms. However, attachment of P. gingivalis, to titanium in particular, was significantly reduced after surface pre-treatment with OligoG and triclosan at 0.01% when compared to controls. Light microscopy and AFM showed that OligoG was biocidal to P. gingivalis, but not S. mutans., Conclusions: OligoG and triclosan when used in combination produced an enhanced antimicrobial effect against two important oral pathogens and reduced bacterial attachment to dental materials such as titanium, even at reduced triclosan concentrations. Whilst the use of triclosan against oral bacteria has been widely documented, its synergistic use with OligoG described here, has not previously been reported. The use of lower concentrations of triclosan, if used in combination therapy with OligoG, could have environmental benefits., Clinical Importance: The potentiation of antimicrobial agents by naturally occurring oligomers such as OligoG may represent a novel, safe adjunct to conventional oral hygiene and periodontal therapy. The ability of OligoG to inhibit the growth and impair bacterial adherence highlights its potential in the management of peri-implantitis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
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37. The effect of alginate oligosaccharides on the mechanical properties of Gram-negative biofilms.
- Author
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Powell LC, Sowedan A, Khan S, Wright CJ, Hawkins K, Onsøyen E, Myrvold R, Hill KE, and Thomas DW
- Subjects
- Acinetobacter baumannii physiology, Alginates chemistry, Alginates isolation & purification, Bacterial Adhesion drug effects, Biomechanical Phenomena, Elastic Modulus, Hydrodynamics, Laminaria chemistry, Microbial Sensitivity Tests, Oligosaccharides chemistry, Pseudomonas aeruginosa physiology, Rheology methods, Shear Strength drug effects, Stress, Mechanical, Acinetobacter baumannii drug effects, Alginates pharmacology, Biofilms drug effects, Oligosaccharides pharmacology, Pseudomonas aeruginosa drug effects
- Abstract
The influence of a novel, safe antibiofilm therapy on the mechanical properties of Pseudomonas aeruginosa and Acinetobacter baumannii biofilms in vitro was characterized. A multiscale approach employing atomic force microscopy (AFM) and rheometry was used to quantify the mechanical disruption of the biofilms by a therapeutic polymer based on a low-molecular weight alginate oligosaccharide (OligoG). AFM demonstrated structural alterations in the biofilms exposed to OligoG, with significantly lower Young's moduli than the untreated biofilms, (149 MPa vs 242 MPa; p < 0.05), a decreased resistance to hydrodynamic shear and an increased surface irregularity (Ra) in the untreated controls (35.2 nm ± 7.6 vs 12.1 nm ± 5.4; p < 0.05). Rheology demonstrated that increasing clinically relevant concentrations of OligoG (<10%) were associated with an increasing phase angle (δ) over a wide range of frequencies (0.1-10 Hz). These results highlight the utility of these techniques for the study of three-dimensional biofilms and for quantifying novel disruption therapies in vitro.
- Published
- 2013
- Full Text
- View/download PDF
38. Cardiac kallikrein-kinin system is upregulated in chronic volume overload and mediates an inflammatory induced collagen loss.
- Author
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Wei CC, Chen Y, Powell LC, Zheng J, Shi K, Bradley WE, Powell PC, Ahmad S, Ferrario CM, and Dell'Italia LJ
- Subjects
- Angiotensin II blood, Angiotensin-Converting Enzyme 2, Animals, Aprotinin pharmacology, Bradykinin blood, Catecholamines blood, Cell Count, Cell Degranulation drug effects, Chymases metabolism, Extracellular Fluid, Gelatinases metabolism, Heart Ventricles diagnostic imaging, Heart Ventricles enzymology, Heart Ventricles pathology, Heart Ventricles physiopathology, Hemodynamics drug effects, Immunohistochemistry, Inflammation complications, Inflammation genetics, Mast Cells drug effects, Mast Cells enzymology, Mast Cells physiology, Models, Cardiovascular, Myocardium metabolism, Peptidyl-Dipeptidase A genetics, Peptidyl-Dipeptidase A metabolism, RNA, Messenger genetics, RNA, Messenger metabolism, Rats, Receptors, Bradykinin metabolism, Ultrasonography, Vascular Fistula diagnostic imaging, Vascular Fistula genetics, Vascular Fistula pathology, Vascular Fistula physiopathology, Collagen metabolism, Inflammation pathology, Kallikrein-Kinin System drug effects, Myocardium pathology, Up-Regulation drug effects, Ventricular Remodeling drug effects
- Abstract
Background: The clinical problem of a "pure volume overload" as in isolated mitral or aortic regurgitation currently has no documented medical therapy that attenuates collagen loss and the resultant left ventricular (LV) dilatation and failure. Here, we identify a potential mechanism related to upregulation of the kallikrein-kinin system in the volume overload of aortocaval fistula (ACF) in the rat., Methodology/principal Findings: LV interstitial fluid (ISF) collection, hemodynamics, and echocardiography were performed in age-matched shams and 4 and 15 wk ACF rats. ACF rats had LV dilatation and a 2-fold increase in LV end-diastolic pressure, along with increases in LV ISF bradykinin, myocardial kallikrein and bradykinin type-2 receptor (BK(2)R) mRNA expression. Mast cell numbers were increased and interstitial collagen was decreased at 4 and 15 wk ACF, despite increases in LV ACE and chymase activities. Treatment with the kallikrein inhibitor aprotinin preserved interstitial collagen, prevented the increase in mast cells, and improved LV systolic function at 4 wk ACF. To establish a cause and effect between ISF bradykinin and mast cell-mediated collagen loss, direct LV interstitial bradykinin infusion in vivo for 24 hrs produced a 2-fold increase in mast cell numbers and a 30% decrease in interstitial collagen, which were prevented by BK(2)R antagonist. To further connect myocardial stretch with cellular kallikrein-kinin system upregulation, 24 hrs cyclic stretch of adult cardiomyocytes and fibroblasts produced increased kallikrein, BK(2)R mRNA expressions, bradykinin protein and gelatinase activity, which were all decreased by the kallikrein inhibitor-aprotinin., Conclusions/significance: A pure volume overload is associated with upregulation of the kallikrein-kinin system and ISF bradykinin, which mediates mast cell infiltration, extracellular matrix loss, and LV dysfunction-all of which are improved by kallikrein inhibition. The current investigation provides important new insights into future potential medical therapies for the volume overload of aortic and mitral regurgitation.
- Published
- 2012
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39. Application of AFM from microbial cell to biofilm.
- Author
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Wright CJ, Shah MK, Powell LC, and Armstrong I
- Subjects
- Bacteria ultrastructure, Bacterial Physiological Phenomena, Biofilms, Microscopy, Atomic Force methods
- Abstract
Atomic Force Microscopy (AFM) has proven itself over recent years as an essential tool for the analysis of microbial systems. This article will review how AFM has been used to study microbial systems to provide unique insight into their behavior and relationship with their environment. Immobilization of live cells has enabled AFM imaging and force measurement to provide understanding of the structure and function of numerous microbial cells. At the macromolecular level AFM investigation into the properties of surface macromolecules and the energies associated with their mechanical conformation and functionality has helped unravel the complex interactions of microbial cells. At the level of the whole cell AFM has provided an integrated analysis of how the microbial cell exploits its environment through its selective, adaptable interface, the cell surface. In addition to these areas of study the AFM investigation of microbial biofilms has been vital for industrial and medical process analysis. There exists a tremendous potential for the future application of AFM to microbial systems and this has been strengthened by the trend to use AFM in combination with other characterization methods, such as confocal microscopy and Raman spectroscopy, to elucidate dynamic cellular processes., (© 2010 Wiley Periodicals, Inc.)
- Published
- 2010
- Full Text
- View/download PDF
40. Antioxidant capacity of lycopene-containing foods.
- Author
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Djuric Z and Powell LC
- Subjects
- Analysis of Variance, Chromatography, High Pressure Liquid, Cucurbitaceae chemistry, Food Preservation, Humans, Lycopene, Vitamin E analogs & derivatives, Antioxidants analysis, Carotenoids analysis, Solanum lycopersicum chemistry
- Abstract
Increased consumption of tomatoes and tomato products has been associated with decreased cancer risks. One fat-soluble compound identified in tomatoes which may be responsible for this association is lycopene. There may, however, be other antioxidants present in tomato-based foods, and total antioxidant capacity may be another way to rate the health benefits of these foods. In this work, we examined the Trolox-equivalent antioxidant capacity (TEAC) of aqueous and organic extracts of lycopene-containing foods: ketchup, fresh tomatoes, tomato paste, tomato sauce, tomato soup, tomato juice, vegetable juice, canned tomatoes and watermelon. Antioxidant activity in these food extracts was greater in the aqueous versus organic fractions, except for watermelon and tomato sauce where the levels were similar in the two fractions. Lycopene levels in the food samples tested, however, were relatively greater in the organic fractions, with the exception of the two juices, which had similar levels in the two fractions, and two highly concentrated tomato products, tomato paste and ketchup, which had relatively higher lycopene levels in the aqueous fractions. The foods with the highest antioxidant capacity per serving overall (tomato soup was highest) did not have the highest lycopene levels. This indicates that it may be important to consume a variety of tomato-containing products in order to obtain the largest variety of dietary antioxidants possible.
- Published
- 2001
- Full Text
- View/download PDF
41. Seminal plasma trace metal levels in industrial workers.
- Author
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Dawson EB, Evans DR, Harris WA, and Powell LC
- Subjects
- Adult, Aged, Chemical Industry, Humans, Male, Metallurgy, Middle Aged, Petroleum, Occupational Exposure analysis, Semen chemistry, Trace Elements analysis
- Abstract
This study compares the seminal plasma trace metal levels of hospital workers with groups of industrial workers in a petroleum refinery, smelter, and chemical plant. The metals measured were the essential metals (copper, zinc, nickel, cobalt, and manganese) and the toxic metals (lead, cadmium, and aluminum). The group mean +/- SE metal level for each group (50 subjects per group) was calculated, and the statistical significance of the group mean differences of the industrial groups with the hospital group (control) was determined by the Student's t-test. The differences observed in the smelter group were increased copper and zinc (p < or = 0.001) and decreased nickel, cobalt, and manganese (p < or = 0.001, < or = 0.01). The refinery group differences were increased copper, zinc, and nickel (p < or = 0.001) but decreased cobalt and manganese (p < or = 0.001). The chemical group differences were increased zinc (p < or = 0.001) and decreased cobalt (p < or = 0.001). The seminal plasma levels of the toxic metals lead and aluminum were increased in each of the industrial groups (p < or = 0.001). Concurrent differences were (1) decreased accumulation of nickel, cobalt, and manganese in the smelter group, (2) decreased cobalt and manganese in the refinery group, and (3) only decreased cobalt in the chemical group.
- Published
- 2000
- Full Text
- View/download PDF
42. Comparison of sperm viability with seminal plasma metal levels.
- Author
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Dawson EB, Ritter S, Harris WA, Evans DR, and Powell LC
- Subjects
- Adult, Humans, Male, Metals metabolism, Semen metabolism, Spermatozoa physiology
- Abstract
This study compares the semen levels of lead (Pb), cadmium (Cd), and aluminum (Al) in relation to live sperm in semen samples from 64 apparently healthy men. The measured levels were separated into live sperm count tertiles (<25% [18 subjects], 25-50% [26 subjects], and >50% [20 subjects]). The mean +/- SD for each group was calculated, and the difference between the means of the high and low tertiles were compared by ANOVA. Significant differences were observed between the high and low live sperm groups for Pb (p < 0.01) and Al (p < 0.05), but not Cd. Spearman's rank correlation between sperm viability and the semen plasma metal levels showed a direct relation to Mg (p < 0.05). However, there was an inverse relation to lead (p < 0.001), cadmium (p < 0.01), and aluminum (p < 0.01). There was no significant correlation between Ca and Zn. Linear regression between the live sperm counts and semen level of the three metals show that metal levels were inversely correlated with the percentage of live sperm (p < 0.001, < 0.01). Apparently, the presence of these metals in the environment and in seminal plasma exerts a toxic effect on sperm.
- Published
- 1998
- Full Text
- View/download PDF
43. Effect of ascorbic acid supplementation on the sperm quality of smokers.
- Author
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Dawson EB, Harris WA, Teter MC, and Powell LC
- Subjects
- Adult, Ascorbic Acid administration & dosage, Ascorbic Acid metabolism, Cell Aggregation, Cell Survival, Humans, Male, Semen metabolism, Sperm Count, Sperm Motility, Spermatozoa drug effects, Ascorbic Acid therapeutic use, Smoking adverse effects, Spermatozoa physiology
- Abstract
Objective: To determine the effect of ascorbic acid supplementation on the sperm quality of heavy smokers., Design: Microscopic examination of semen for 1 month during supplementation with placebo or ascorbic acid at dose levels of 200 or 1,000 mg/d., Setting: Department of Obstetrics and Gynecology, The University of Texas Medical Branch., Participants: Seventy-five men (20 to 35 years old) randomly divided into one of three supplementation groups: placebo, 200 mg and 1,000 mg of ascorbic acid., Main Outcome: Improvement in sperm quality as compared with presupplementation levels and between the three treatment groups., Results: The placebo group showed no improvement in sperm quality. The groups receiving ascorbic acid showed improvement in sperm quality with most improvement in the 1,000-mg group. Pearson's correlation showed statistically significant relationships between the weekly group means of serum and seminal plasma ascorbic acid levels and sperm qualities., Conclusions: Ascorbic acid supplementation of heavy smokers in excess of 200 mg/d results in improved sperm quality.
- Published
- 1992
44. Relationship between ascorbic acid and male fertility.
- Author
-
Dawson EB, Harris WA, and Powell LC
- Subjects
- Adult, Agglutination, Aging, Ascorbic Acid therapeutic use, Clinical Trials as Topic, Evaluation Studies as Topic, Humans, Infertility, Male drug therapy, Male, Middle Aged, Semen metabolism, Ascorbic Acid metabolism, Diet, Fertility, Spermatozoa physiology
- Published
- 1990
- Full Text
- View/download PDF
45. Locally aggressive granular cell tumor causing priapism of the crus of the clitoris. A light and ultrastructural study, with observations concerning the pathogenesis of fibrosis of the corpus cavernosum in priapism.
- Author
-
Slavin RE, Christie JD, Swedo J, and Powell LC Jr
- Subjects
- Adult, Female, Humans, Immunoenzyme Techniques, Male, Middle Aged, Neoplasms, Muscle Tissue complications, Neoplasms, Muscle Tissue immunology, Vulvar Neoplasms complications, Vulvar Neoplasms immunology, Clitoris, Neoplasms, Muscle Tissue pathology, Priapism etiology, Vulvar Neoplasms pathology
- Abstract
A case of focal priapism of the clitoris caused by a microscopic granular cell tumor (GCT) is described. This neoplasm is considered locally aggressive because it invades the lumens of peripheral cavernous sinuses of the crus of the clitoris. Caverns adjacent to those invaded by tumor exhibit stasis, telangiectasia, and necrosis of the smooth muscle of the trabecular wall. These alterations lead to telescoping collapse and compression of the cavernous spaces and culminate in fibrosis. Ultrastructurally, replicated basal lamina is found surrounding clusters of granular cells. We suspect that the multilayered lamina, in addition to being produced by tumor cells, is derived from the trabecular endothelium surrounding the caverns invaded by the GCT. The replication of the basal lamina may be provoked by cycles of injury and repair to these vessels caused by repeated episodes of prolonged vascular stasis. A peculiar large vein with perforating branches was observed in the center of the cavernous spaces of the crus. This vein is not found in normal crura and, therefore, represents a morphologic adaptation created to drain the cavernous spaces.
- Published
- 1986
- Full Text
- View/download PDF
46. The obstetrical management of conjoined twins.
- Author
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Vaughn TC and Powell LC
- Subjects
- Cesarean Section, Delivery, Obstetric methods, Female, Humans, Infant, Newborn, Pregnancy, Prenatal Diagnosis, Ultrasonography, Twins, Conjoined diagnosis, Twins, Conjoined surgery
- Abstract
A pair of conjoined twins (thoracopagus) was delivered abdominally after antepartum diagnosis. Obstetrical planning is more likely to be successful with antepartum diagnosis, which can be done only if the possibility of conjoining is considered with each twin gestation. Once a twin gestation is suspected, ultrasonography should be performed for confirmation. Conjoined twins should be suspected in a gravid mother with multiple gestations and an abnormal fetal attitude. When the images cannot be separated on ultrasonography, amniographic examination, using a double contrast medium of oil-water, should demonstrate dye in the gastrointestinal tract and a union between the twins, as well as establish the presence of a monoamniotic sac. Because of increased fetal morbidity and mortality of vaginal delivery in monoamniotic twins, even if not conjoined, elective cesarean section at term will ensure the best chance for fetal survival.
- Published
- 1979
47. Carcinoma in situ of the vulva. A clinicopathologic study of 50 cases.
- Author
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Powell LC Jr, Dinh TV, Rajaraman S, Hannigan EV, Dillard EA Jr, Yandell RB, and To T
- Subjects
- Adult, Aged, Carcinoma in Situ complications, Carcinoma in Situ drug therapy, Carcinoma in Situ surgery, Female, Follow-Up Studies, Genital Neoplasms, Female complications, Humans, Middle Aged, Pregnancy, Recurrence, Sexually Transmitted Diseases complications, Vulvar Neoplasms complications, Vulvar Neoplasms drug therapy, Vulvar Neoplasms surgery, Carcinoma in Situ pathology, Vulvar Neoplasms pathology
- Abstract
The authors reviewed 50 cases of carcinoma in situ of the vulva treated at the University of Texas Medical Branch, Galveston, from 1975 to 1984. Sixty-two percent of the patients were premenopausal. The most frequent complaint was vulvar itching. Twenty-six percent of the patients were asymptomatic. Recurrences were frequent (25%) and were associated with multifocal lesions, involved surgical margins and the bowenoid histologic type. Superficially invasive carcinoma was detected in 8% of patients, mostly postmenopausal women with simplex histologic types. Immunohistochemical studies failed to detect papillomavirus- or herpesvirus-associated antigens in any of the cases. Follow-up of 48 patients from six months to ten years revealed no mortality from invasive cancer.
- Published
- 1986
48. The ultrastructural response of human endometrium to medroxyprogesterone acetate.
- Author
-
Roberts DK, Horbelt DV, and Powell LC Jr
- Subjects
- Adult, Cell Nucleus ultrastructure, Endometrium ultrastructure, Female, Humans, Inclusion Bodies ultrastructure, Time Factors, Endometrium drug effects, Medroxyprogesterone pharmacology
- Abstract
Medroxyprogesterone acetate is a steroid compound similar to progesterone in structure and function. Thirty women were given 150 mg. of medroxyprogesterone intramuscularly, and samples of the endometrium were examined by light and electron microscopy. The initial response of normal human endometrium was maturation and then inhibition. By 50 days after injection, the atrophic changes began to reverse, and by Day 90, after injection the tissue resembled normal proliferative endometrium. A previously undescribed nuclear inclusion body is present; however, its significance is unclear at this time. On the basis of ultrastructural changes, medroxyprogesterone appeared not to exert a significant influence on the endometrium past 90 days at this dosage.
- Published
- 1975
- Full Text
- View/download PDF
49. Intrauterine fetal transfusion.
- Author
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Powell LC Jr and Schreiber MH
- Subjects
- Amniocentesis, Erythroblastosis, Fetal diagnosis, Female, Fetus diagnostic imaging, Humans, Methods, Pregnancy, Radiography, Blood Transfusion, Intrauterine adverse effects, Erythroblastosis, Fetal therapy
- Published
- 1974
50. Rapid treatment approach to human sexual inadequacy.
- Author
-
Powell LC Jr, Blakeney P, Croft H, and Pulliam GP
- Subjects
- Anatomy, Audiovisual Aids, Coitus, Communication, Fear, Female, Humans, Interview, Psychological, Male, Marriage, Physical Examination, Physiology, Sex Education, Sexual Dysfunction, Physiological therapy
- Published
- 1974
- Full Text
- View/download PDF
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