71 results on '"Orr DJ"'
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2. FOLLICULAR CARCINOMA OF THYROID PRESENTING AS BACK PAIN LEADING TO A DELAY IN DIAGNOSIS
- Author
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Simpson, H, primary, Orr, DJ, additional, John, PJ, additional, Wilson, K, additional, and Braidwood, AS, additional
- Published
- 1994
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3. Are paediatric burns more common in asylum seekers? An analysis of paediatric burn admissions.
- Author
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Dempsey MP and Orr DJ
- Abstract
The number of asylum seekers in Ireland has increased dramatically over the last 10 years. Based on our impression that the number of children admitted to our burn unit was disproportionately represented by children of asylum seekers we performed an audit to establish (1) what proportion of admissions are from this subgroup and (2) the characteristics of their burns. All paediatric burn admissions from May 2003 to April 2004 were reviewed. Data collected from a retrospective chart review included patient demographics and details of the burn injuries. The National Census of 2002 and the Office of the Refugee Applications Commissioner were consulted for population statistics. Total burn admissions for the period were 126: Irish nationals (n=107), non-national residents (n=2), asylum seekers (n=14) and patients of unknown asylum status (n=3, excluded from study). In the asylum seeker group, the median age was 18.6 months (range 10 months-5.3 years) with the majority less than 2 years (n=11). All burns occurred in the domestic setting. Scalds accounted for 13 cases, one contact burn occurred from a hot grill. The median total body surface area burned was 5.7% (range 1.5-26%). The National Census of 2002 recorded a population of 3,917,203. With less than 12,000 asylum seekers in the country, they comprise only approximately 0.3% of the population yet they account for 11.4% of the burn patients admitted to our unit, p<0.0001. Children of asylum seekers are over-represented in our series of paediatric admissions for burns and are more likely than Irish children to sustain a burn at a younger age and in the domestic setting. This may indicate an increased risk of injury and warrants further investigation. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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4. Axial Growth and Myopia Progression After Discontinuing Soft Multifocal Contact Lens Wear.
- Author
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Berntsen DA, Ticak A, Orr DJ, Giannoni AG, Sinnott LT, Mutti DO, Jones-Jordan LA, and Walline JJ
- Abstract
Importance: For myopia control to be beneficial, it would be important that the benefit of treatment (slowed eye growth) is not lost because of faster than normal growth (rebound) after discontinuing treatment., Objective: To determine whether there is a loss of treatment effect (rebound) after discontinuing soft multifocal contact lenses in children with myopia., Design, Setting, and Participants: The Bifocal Lenses in Nearsighted Kids 2 (BLINK2) cohort study involved children with myopia (aged 11-17 years at BLINK2 baseline) who completed the BLINK Study randomized clinical trial. Enrollment was from September 2019 through January 2021; follow-up was completed in January 2024. In the BLINK2 Study, all children wore high-add (+2.50 diopter [D]) multifocal soft contact lenses for 2 years and single-vision soft contact lenses during the third year to determine if rebound occurred., Exposure: High-add multifocal soft contact lenses and single-vision soft contact lenses., Main Outcomes and Measures: Eye length (optical biometry) and refractive error (cycloplegic autorefraction) were measured annually., Results: Of 248 participants enrolled in BLINK2, 235 completed the study. The median age at the baseline visit was 15 years (range, 11-17 years); 146 participants (59%) were female, and 102 (41%) were male. At baseline for BLINK2, mean (SD) axial length and spherical equivalent refractive error were 25.2 (0.9) mm and -3.40 (1.40) D, respectively. After participants switched from multifocal to single-vision contact lenses, axial elongation increased by 0.03 mm per year (95% CI, 0.01 to 0.05) regardless of their original BLINK treatment assignment (P = .81). There was also an increase in myopia progression after switching to single-vision lenses of -0.17 D per year (95% CI, -0.22 to -0.12) that did not depend on the original BLINK treatment assignment (P = .57). There continued to be a difference in axial length and refractive error throughout BLINK2 based on the BLINK Study treatment assignment with the original high-add group having shorter eyes and less myopia than the original medium-add (+1.50 D) and single-vision groups., Conclusions and Relevance: The BLINK2 Study found no evidence of a loss of treatment effect after discontinuing multifocal contact lenses in older teenagers. These data suggest eye growth and myopia progression returned to faster but age-expected rates and support continuing multifocal lenses until cessation of elongation and progression.
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- 2025
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5. Modeling with uncertainty quantification reveals the essentials of a non-canonical algal carbon-concentrating mechanism.
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Steensma AK, Kaste JAM, Heo J, Orr DJ, Sung CL, Shachar-Hill Y, and Walker BJ
- Abstract
The thermoacidophilic red alga Cyanidioschyzon merolae survives its challenging environment likely in part by operating a carbon-concentrating mechanism (CCM). Here, we demonstrated that C. merolae's cellular affinity for CO2 is stronger than the affinity of its rubisco for CO2. This finding provided additional evidence that C. merolae operates a CCM while lacking the structures and functions characteristic of CCMs in other organisms. To test how such a CCM could function, we created a mathematical compartmental model of a simple CCM, distinct from those we have seen previously described in detail. The results of our modeling supported the feasibility of this proposed minimal and non-canonical CCM in C. merolae. To facilitate the robust modeling of this process, we measured and incorporated physiological and enzymatic parameters into the model. Additionally, we trained a surrogate machine learning model to emulate the mechanistic model and characterized the effects of model parameters on key outputs. This parameter exploration enabled us to identify model features that influenced whether the model met the experimentally derived criteria for functional carbon concentration and efficient energy usage. Such parameters included cytosolic pH, bicarbonate pumping cost and kinetics, cell radius, carboxylation velocity, number of thylakoid membranes, and CO2 membrane permeability. Our exploration thus suggested that a non-canonical CCM could exist in C. merolae and illuminated the essential features generally necessary for CCMs to function., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists.)
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- 2024
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6. Regulation of Rubisco activity by interaction with chloroplast metabolites.
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Lobo AKM, Orr DJ, and Carmo-Silva E
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- Photosynthesis, Plant Proteins metabolism, Plant Proteins chemistry, Carbon Dioxide metabolism, Ribulosephosphates metabolism, Fructosephosphates metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Ribulose-Bisphosphate Carboxylase chemistry, Chloroplasts metabolism, Chloroplasts enzymology, Molecular Docking Simulation, Oryza metabolism, Oryza enzymology
- Abstract
Rubisco activity is highly regulated and frequently limits carbon assimilation in crop plants. In the chloroplast, various metabolites can inhibit or modulate Rubisco activity by binding to its catalytic or allosteric sites, but this regulation is complex and still poorly understood. Using rice Rubisco, we characterised the impact of various chloroplast metabolites which could interact with Rubisco and modulate its activity, including photorespiratory intermediates, carbohydrates, amino acids; as well as specific sugar-phosphates known to inhibit Rubisco activity - CABP (2-carboxy-d-arabinitol 1,5-bisphosphate) and CA1P (2-carboxy-d-arabinitol 1-phosphate) through in vitro enzymatic assays and molecular docking analysis. Most metabolites did not directly affect Rubisco in vitro activity under both saturating and limiting concentrations of Rubisco substrates, CO2 and RuBP (ribulose-1,5-bisphosphate). As expected, Rubisco activity was strongly inhibited in the presence of CABP and CA1P. High physiologically relevant concentrations of the carboxylation product 3-PGA (3-phosphoglyceric acid) decreased Rubisco activity by up to 30%. High concentrations of the photosynthetically derived hexose phosphates fructose 6-phosphate (F6P) and glucose 6-phosphate (G6P) slightly reduced Rubisco activity under limiting CO2 and RuBP concentrations. Biochemical measurements of the apparent Vmax and Km for CO2 and RuBP (at atmospheric O2 concentration) and docking interactions analysis suggest that CABP/CA1P and 3-PGA inhibit Rubisco activity by binding tightly and loosely, respectively, to its catalytic sites (i.e. competing with the substrate RuBP). These findings will aid the design and biochemical modelling of new strategies to improve the regulation of Rubisco activity and enhance the efficiency and sustainability of carbon assimilation in rice., (© 2024 The Author(s).)
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- 2024
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7. Radiometric determination of rubisco activation state and quantity in leaves.
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Ashton CJ, Page R, Lobo AKM, Amaral J, Siqueira JA, Orr DJ, and Carmo-Silva E
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- Photosynthesis physiology, Radiometry methods, Enzyme Assays methods, Carbon Dioxide metabolism, Carbon Dioxide analysis, Ribulose-Bisphosphate Carboxylase metabolism, Plant Leaves metabolism, Plant Leaves chemistry, Plant Leaves enzymology, Enzyme Activation
- Abstract
Rubisco is the key enzyme in photosynthesis, catalyzing fixation of carbon dioxide from the atmosphere into energy storage molecules. Several inefficiencies in Rubisco limit the rate of photosynthesis, and, therefore, the growth of the plant. Rubisco is sensitive to light, making deactivation of the enzyme upon sampling likely. Moreover, the indirect methods often used to study its activity make obtaining reliable data difficult. In this Chapter, we describe an approach to generate reliable and repeatable data for Rubisco activities, activation state and abundance in plant leaves. We include methods to sample and extract proteins, minimizing Rubisco degradation and deactivation. We describe radiometric techniques to measure Rubisco activities and calculate its activation state at the time of sampling, and to quantify its abundance., (Copyright © 2024. Published by Elsevier Inc.)
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- 2024
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8. Purification of Rubisco from Leaves.
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Amaral J, Lobo AKM, Carmo-Silva E, and Orr DJ
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- Chromatography, Ion Exchange methods, Polyethylene Glycols chemistry, Ribulose-Bisphosphate Carboxylase isolation & purification, Ribulose-Bisphosphate Carboxylase chemistry, Ribulose-Bisphosphate Carboxylase metabolism, Plant Leaves chemistry, Plant Leaves enzymology
- Abstract
Rubisco fixes CO
2 through the carboxylation of ribulose 1,5-bisphosphate (RuBP) during photosynthesis, enabling the synthesis of organic compounds. The natural diversity of Rubisco properties represents an opportunity to improve its performance and there is considerable research effort focusing on better understanding the properties and regulation of the enzyme. This chapter describes a method for large-scale purification of Rubisco from leaves. After the extraction of Rubisco from plant leaves, the enzyme is separated from other proteins by fractional precipitation with polyethylene glycol followed by ion-exchange chromatography. This method enables the isolation of Rubisco in large quantities for a wide range of biochemical applications., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)- Published
- 2024
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9. Extraction of Soluble Proteins from Leaves.
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Carmo-Silva E, Page R, Marsden CJ, Gjindali A, and Orr DJ
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- Solubility, Plant Leaves chemistry, Plant Proteins isolation & purification
- Abstract
Protein biochemistry can provide valuable answers to better understand plant performance and responses to the surrounding environment. In this chapter, we describe the process of extracting proteins from plant leaf samples. We highlight the key aspects to take into consideration to preserve protein integrity, from sample collection to extraction and preparation or storage for subsequent analysis of protein abundance and/or enzymatic activities., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)
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- 2024
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10. Frailty Assessment in Vascular OUtpatients Review (FAVOUR) protocol: single-centre prospective cohort study comparing feasibility and prognostic value of commonly used frailty assessment tools.
- Author
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Welsh SA, Hussey K, Brittenden J, Orr DJ, and Quinn T
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- Adult, Humans, Aged, Prospective Studies, Outpatients, Prognosis, Feasibility Studies, State Medicine, Geriatric Assessment methods, Frail Elderly, Frailty diagnosis, Frailty complications
- Abstract
Introduction: Frailty has consistently demonstrated associations with poorer healthcare outcomes. Vascular guidelines have recognised the importance of frailty assessment. However, an abundance of frailty tools and a lack of prospective studies confirming suitability of routine frailty assessment in clinical practice has delayed the uptake of these guidelines. The Frailty Assessment in Vascular OUtpatients Review study speaks to this evidence gap. The primary aim is to assess feasibility of implementing routine frailty assessment in a reproducible outpatient setting. Secondary objectives include comparing prognostic values and interuser agreement across five frailty assessment tools., Methods and Analysis: This single-centre prospective cohort study of feasibility is conducted in a rapid-referral vascular surgery clinic, serving a population of 2 million. Adults with capacity (>18 years), attending a clinic for any reason, are eligible for inclusion. Five assessments are completed by patient (Rockwood Clinical Frailty Scale (CFS) and Frail NonDisabled Questionnaire), clinician (CFS, Healthcare Improvement Scotland FRAIL tool and 'Initial Clinical Evaluation') and researcher (11-item modified Frailty Index). Consistent with feasibility objectives, outcome measures include recruitment rates, frailty assessment completion rates, time-to-complete assessments and interuser variability. Electronic follow-up at 30 days and 1 year will assess home-time and mortality as prognostic indicators. Patients treated surgically/endovascularly will undergo additional 30-day and 1-year postoperative follow-up, outcome measures include: surgical procedure, mortality, complications (according to Clavien-Dindo Classification), length of stay, readmission rates, non-home discharge, home-time, higher social care requirements on discharge and amputation-free survival. Prognostic value will be compared by area under receiver operating characteristic curves. Continuous outcome variables will be analysed using Spearman's rank correlation coefficient. Interuser agreement will be compared by percentage agreement in Cohen's kappa coefficient. ETHICS AND DISSEMINATION: The study is sponsored by National Health Service Greater Glasgow and Clyde (R&IUGN23CE014). London-Riverside REC (23/PR/0062) granted ethical approval. Results will be disseminated through publication in peer-reviewed vascular surgery and geriatric medicine themed journals and presentation at similar scientific conferences., Trials Registration Number: NCT06040658. Stage of study: pre-results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2023
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11. A systematic review of frailty assessment tools used in vascular surgery research.
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Welsh SA, Pearson RC, Hussey K, Brittenden J, Orr DJ, and Quinn T
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- Humans, Vascular Surgical Procedures adverse effects, Consensus, Databases, Factual, Frailty diagnosis, Specialties, Surgical
- Abstract
Objective: Frailty is common in vascular patients and is recognized for its prognostic value. In the absence of consensus, a multitude of frailty assessment tools exist. This systematic review aimed to quantify the variety in these tools and describe their content and application to inform future research and clinical practice., Methods: Multiple cross-disciplinary electronic literature databases were searched from inception to August 2022. Studies describing frailty assessment in a vascular surgical population were eligible. Data extraction to a validated template included patient demographics, tool content, and analysis methods. A secondary systematic search for papers describing the psychometric properties of commonly used frailty tools was then performed., Results: Screening 5358 records identified 111 eligible studies, with an aggregate population of 5,418,236 patients. Forty-three differing frailty assessment tools were identified. One-third of these failed to assess frailty as a multidomain deficit and there was a reliance on assessing function and presence of comorbidity. Substantial methodological variability in data analysis and lack of methodological description was also identified. Published psychometric assessment was available for only 4 of the 10 most commonly used frailty tools. The Clinical Frailty Scale was the most studied and demonstrates good psychometric properties within a surgical population., Conclusions: Substantial heterogeneity in frailty assessment is demonstrated, precluding meaningful comparisons of services and data pooling. A uniform approach to assessment is required to guide future frailty research. Based on the literature, we make the following recommendations: frailty should be considered a continuous construct and the reporting of frailty tools' application needs standardized. In the absence of consensus, the Clinical Frailty Scale is a validated tool with good psychometric properties that demonstrates usefulness in vascular surgery., Competing Interests: Disclosures None., (Copyright © 2023 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
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12. Dynamics of Rubisco regulation by sugar phosphate derivatives and their phosphatases.
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Orr DJ, Robijns AKJ, Baker CR, Niyogi KK, and Carmo-Silva E
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- Phosphoric Monoester Hydrolases metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Tissue Plasminogen Activator
- Abstract
Regulating the central CO2-fixing enzyme Rubisco is as complex as its ancient reaction mechanism and involves interaction with a series of cofactors and auxiliary proteins that activate catalytic sites and maintain activity. A key component among the regulatory mechanisms is the binding of sugar phosphate derivatives that inhibit activity. Removal of inhibitors via the action of Rubisco activase is required to restore catalytic competency. In addition, specific phosphatases dephosphorylate newly released inhibitors, rendering them incapable of binding to Rubisco catalytic sites. The best studied inhibitor is 2-carboxy-d-arabinitol 1-phosphate (CA1P), a naturally occurring nocturnal inhibitor that accumulates in most species during darkness and low light, progressively binding to Rubisco. As light increases, Rubisco activase removes CA1P from Rubisco, and the specific phosphatase CA1Pase dephosphorylates CA1P to CA, which cannot bind Rubisco. Misfire products of Rubisco's complex reaction chemistry can also act as inhibitors. One example is xylulose-1,5-bisphosphate (XuBP), which is dephosphorylated by XuBPase. Here we revisit key findings related to sugar phosphate derivatives and their specific phosphatases, highlighting outstanding questions and how further consideration of these inhibitors and their role is important for better understanding the regulation of carbon assimilation., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Experimental Biology.)
- Published
- 2023
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13. The Effect of Multifocal Soft Contact Lens Wear on Axial and Peripheral Eye Elongation in the BLINK Study.
- Author
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Mutti DO, Sinnott LT, Berntsen DA, Jones-Jordan LA, Orr DJ, and Walline JJ
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- Child, Eyeglasses, Female, Humans, Male, Refraction, Ocular, Retina, Contact Lenses, Hydrophilic, Myopia therapy, Vision, Low
- Abstract
Purpose: The purpose of this study was to compare axial and peripheral eye elongation during myopia therapy with multifocal soft contact lenses., Methods: Participants were 294 children (177 [60.2%] girls) age 7 to 11 years old with between -0.75 diopters (D) and -5.00 D of myopia (spherical component) and less than 1.00 D astigmatism at baseline. Children were randomly assigned to Biofinity soft contact lenses for 3 years: D-designs with a +2.50 D addition, +1.50 D addition, or single vision. Five measurements of eye length were averaged at the fovea, ±20°, and ±30° in the horizontal and vertical meridians of the right eye using the Haag-Streit Lenstar LS 900., Results: Axial elongation over 3 years with single vision contact lenses was greater than peripheral elongation in the superior and temporal retinal qeuadrants by 0.07 mm (95% confidence interval [CI] = 0.05 to 0.09 mm) and 0.06 mm (95% CI = 0.03 to 0.09 mm) and similar in the inferior and nasal quadrants. Axial elongation with +2.50 D addition multifocal contact lenses was similar to peripheral elongation in the superior retinal quadrant and less than peripheral elongation in the inferior and nasal quadrants by -0.04 mm (95% CI = -0.06 to -0.01 mm) and -0.06 mm (95% CI = -0.09 to -0.02 mm)., Conclusions: Wearing +2.50 D addition multifocal contact lenses neutralized or reversed the increase in retinal steepness with single vision lenses. The mismatch between greater inhibition of elongation at the fovea than peripherally despite greater peripheral myopic defocus suggests that optical myopia therapy may operate through extensive spatial integration or mechanisms other than local defocus.
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- 2022
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14. Structural plasticity enables evolution and innovation of RuBisCO assemblies.
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Liu AK, Pereira JH, Kehl AJ, Rosenberg DJ, Orr DJ, Chu SKS, Banda DM, Hammel M, Adams PD, Siegel JB, and Shih PM
- Abstract
Oligomerization is a core structural feature that defines the form and function of many proteins. Most proteins form molecular complexes; however, there remains a dearth of diversity-driven structural studies investigating the evolutionary trajectory of these assemblies. Ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) is one such enzyme that adopts multiple assemblies, although the origins and distribution of its different oligomeric states remain cryptic. Here, we retrace the evolution of ancestral and extant form II RuBisCOs, revealing a complex and diverse history of oligomerization. We structurally characterize a newly discovered tetrameric RuBisCO, elucidating how solvent-exposed surfaces can readily adopt new interactions to interconvert or give rise to new oligomeric states. We further use these principles to engineer and demonstrate how changes in oligomerization can be mediated by relatively few mutations. Our findings yield insight into how structural plasticity may give rise to new oligomeric states.
- Published
- 2022
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15. The surgical burden of sebaceous naevus excision in childhood.
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Casey MC and Orr DJ
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- Child, Humans, Nevus, Retrospective Studies, Anesthetics, General, Carcinoma, Basal Cell surgery, Skin Neoplasms pathology, Skin Neoplasms surgery
- Abstract
Prophylactic excision of sebaceous naevi during childhood has been common practice due to the risk of malignant transformation into basal cell carcinoma (BCC). With incidence of BCC now recognised as 0.8%, a more conservative approach to management is being advocated. The aim of this study was to evaluate the surgical burden produced by the traditional approach of prophylactic excision in childhood., Methods: A retrospective analysis of all sebaceous naevi excised in a tertiary-referral paediatric hospital between January 2007 and December 2017 was conducted., Results: No malignancy was identified in this consecutive series of 189 patients. General anaesthetic was required in 99% of cases with 23% (n = 43) requiring more than one general anaesthetic. Staged-excision was performed in 17% (n = 33), with tissue expanders used in 2% (n = 3) and rotation flap in 1.6% (n = 3). Post-operative sequelae requiring re-operative intervention occurred in 7% (n = 13)., Conclusions: Routine excision of sebaceous naevi during childhood carries a high burden of care and is not necessary for cancer prevention. Excision can be safely delayed until patients are old enough to participate in decision-making about their surgery., Competing Interests: Declaration of Competing Interest Nothing to disclose., (Copyright © 2022. Published by Elsevier Ltd.)
- Published
- 2022
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16. Rubiscosome gene expression is balanced across the hexaploid wheat genome.
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Caruana L, Orr DJ, and Carmo-Silva E
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- Gene Expression, Gene Expression Regulation, Plant, Genome, Plant genetics, Polyploidy, Ribulose-Bisphosphate Carboxylase metabolism, Triticum genetics, Triticum metabolism
- Abstract
Functional and active Rubisco is essential for CO
2 fixation and is a primary target for engineering approaches to increasing crop yields. However, the assembly and maintenance of active Rubisco are dependent on the coordinated biosynthesis of at least 11 nuclear-encoded proteins, termed the 'Rubiscosome'. Using publicly available gene expression data for wheat (Triticum aestivum L.), we show that the expression of Rubiscosome genes is balanced across the three closely related subgenomes that form the allohexaploid genome. Each subgenome contains a near complete set of homoeologous genes and contributes equally to overall expression, both under optimal and under heat stress conditions. The expression of the wheat thermo-tolerant Rubisco activase isoform 1β increases under heat stress and remains balanced across the subgenomes, albeit with a slight shift towards greater contribution from the D subgenome. The findings show that the gene copies in all three subgenomes need to be accounted for when designing strategies for crop improvement., (© 2022. The Author(s).)- Published
- 2022
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17. A procedure to introduce point mutations into the Rubisco large subunit gene in wild-type plants.
- Author
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Lin MT, Orr DJ, Worrall D, Parry MAJ, Carmo-Silva E, and Hanson MR
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- Chloroplasts genetics, Ribulose-Bisphosphate Carboxylase metabolism, Nicotiana enzymology, Gene Editing methods, Genes, Plant genetics, Point Mutation genetics, Ribulose-Bisphosphate Carboxylase genetics, Nicotiana genetics
- Abstract
Photosynthetic inefficiencies limit the productivity and sustainability of crop production and the resilience of agriculture to future societal and environmental challenges. Rubisco is a key target for improvement as it plays a central role in carbon fixation during photosynthesis and is remarkably inefficient. Introduction of mutations to the chloroplast-encoded Rubisco large subunit rbcL is of particular interest for improving the catalytic activity and efficiency of the enzyme. However, manipulation of rbcL is hampered by its location in the plastome, with many species recalcitrant to plastome transformation, and by the plastid's efficient repair system, which can prevent effective maintenance of mutations introduced with homologous recombination. Here we present a system where the introduction of a number of silent mutations into rbcL within the model plant Nicotiana tabacum facilitates simplified screening via additional restriction enzyme sites. This system was used to successfully generate a range of transplastomic lines from wild-type N. tabacum with stable point mutations within rbcL in 40% of the transformants, allowing assessment of the effect of these mutations on Rubisco assembly and activity. With further optimization the approach offers a viable way forward for mutagenic testing of Rubisco function in planta within tobacco and modification of rbcL in other crops where chloroplast transformation is feasible. The transformation strategy could also be applied to introduce point mutations in other chloroplast-encoded genes., (© 2021 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)
- Published
- 2021
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18. Heat-induced changes in the abundance of wheat Rubisco activase isoforms.
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Degen GE, Orr DJ, and Carmo-Silva E
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- Photosynthesis, Plant Proteins genetics, Plant Proteins metabolism, Protein Isoforms genetics, Tissue Plasminogen Activator, Ribulose-Bisphosphate Carboxylase metabolism, Triticum genetics, Triticum metabolism
- Abstract
The Triticum aestivum (wheat) genome encodes three isoforms of Rubisco activase (Rca) differing in thermostability, which could be exploited to improve the resilience of this crop to global warming. We hypothesized that elevated temperatures would cause an increase in the relative abundance of heat-stable Rca1β. Wheat plants were grown at 25° C : 18°C (day : night) and exposed to heat stress (38° C : 22°C) for up to 5 d at pre-anthesis. Carbon (C) assimilation, Rubisco activity, CA1Pase activity, transcripts of Rca1β, Rca2β, and Rca2α, and the quantities of the corresponding protein products were measured during and after heat stress. The transcript of Rca1β increased 40-fold in 4 h at elevated temperatures and returned to the original level after 4 h upon return of plants to control temperatures. Rca1β comprised up to 2% of the total Rca protein in unstressed leaves but increased three-fold in leaves exposed to elevated temperatures for 5 d and remained high at 4 h after heat stress. These results show that elevated temperatures cause rapid changes in Rca gene expression and adaptive changes in Rca isoform abundance. The improved understanding of the regulation of C assimilation under heat stress will inform efforts to improve wheat productivity and climate resilience., (© 2020 The Authors New Phytologist © 2020 New Phytologist Foundation.)
- Published
- 2021
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19. CRISPR-Cas9-Mediated Mutagenesis of the Rubisco Small Subunit Family in Nicotiana tabacum .
- Author
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Donovan S, Mao Y, Orr DJ, Carmo-Silva E, and McCormick AJ
- Abstract
Engineering the small subunit of the key CO
2 -fixing enzyme Rubisco (SSU, encoded by rbcS ) in plants currently poses a significant challenge, as many plants have polyploid genomes and SSUs are encoded by large multigene families. Here, we used CRISPR-Cas9-mediated genome editing approach to simultaneously knock-out multiple rbcS homologs in the model tetraploid crop tobacco ( Nicotiana tabacum cv . Petit Havana). The three rbcS homologs rbcS_S1a, rbcS_S1b and rbcS_T1 account for at least 80% of total rbcS expression in tobacco. In this study, two multiplexing guide RNAs (gRNAs) were designed to target homologous regions in these three genes. We generated tobacco mutant lines with indel mutations in all three genes, including one line with a 670 bp deletion in rbcS-T1 . The Rubisco content of three selected mutant lines in the T1 generation was reduced by ca . 93% and mutant plants accumulated only 10% of the total biomass of wild-type plants. As a second goal, we developed a proof-of-principle approach to simultaneously introduce a non-native rbcS gene while generating the triple SSU knockout by co-transformation into a wild-type tobacco background. Our results show that CRISPR-Cas9 is a viable tool for the targeted mutagenesis of rbcS families in polyploid species and will contribute to efforts aimed at improving photosynthetic efficiency through expression of superior non-native Rubisco enzymes in plants., Competing Interests: The 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 © 2020 Donovan, Mao, Orr, Carmo-Silva and McCormick.)- Published
- 2020
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20. Overcoming the limitations of Rubisco: fantasy or realistic prospect?
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Orr DJ and Parry MAJ
- Subjects
- Plant Proteins metabolism, Plants enzymology, Ribulose-Bisphosphate Carboxylase metabolism
- Published
- 2020
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21. During photosynthetic induction, biochemical and stomatal limitations differ between Brassica crops.
- Author
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Taylor SH, Orr DJ, Carmo-Silva E, and Long SP
- Subjects
- Brassica physiology, Chlorophyll metabolism, Crops, Agricultural metabolism, Crops, Agricultural physiology, Light, Models, Biological, Plant Leaves metabolism, Plant Proteins metabolism, Plant Stomata physiology, Ribulose-Bisphosphate Carboxylase metabolism, Brassica metabolism, Photosynthesis physiology, Plant Stomata metabolism
- Abstract
Interventions to increase crop radiation use efficiency rely on understanding of how biochemical and stomatal limitations affect photosynthesis. When leaves transition from shade to high light, slow increases in maximum Rubisco carboxylation rate and stomatal conductance limit net CO
2 assimilation for several minutes. However, as stomata open intercellular [CO2 ] increases, so electron transport rate could also become limiting. Photosynthetic limitations were evaluated in three important Brassica crops: Brassica rapa, Brassica oleracea and Brassica napus. Measurements of induction after a period of shade showed that net CO2 assimilation by B. rapa and B. napus saturated by 10 min. A new method of analyzing limitations to induction by varying intercellular [CO2 ] showed this was due to co-limitation by Rubisco and electron transport. By contrast, in B. oleracea persistent Rubisco limitation meant that CO2 assimilation was still recovering 15 min after induction. Correspondingly, B. oleracea had the lowest Rubisco total activity. The methodology developed, and its application here, shows a means to identify the basis of variation in photosynthetic efficiency in fluctuating light, which could be exploited in breeding and bioengineering to improve crop productivity., (© 2020 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.)- Published
- 2020
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22. Generating and characterizing single- and multigene mutants of the Rubisco small subunit family in Arabidopsis.
- Author
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Khumsupan P, Kozlowska MA, Orr DJ, Andreou AI, Nakayama N, Patron N, Carmo-Silva E, and McCormick AJ
- Subjects
- CRISPR-Cas Systems, Gene Knockout Techniques, Mutation, Phenotype, Arabidopsis genetics, Arabidopsis metabolism, Ribulose-Bisphosphate Carboxylase genetics, Ribulose-Bisphosphate Carboxylase metabolism
- Abstract
The primary CO2-fixing enzyme Rubisco limits the productivity of plants. The small subunit of Rubisco (SSU) can influence overall Rubisco levels and catalytic efficiency, and is now receiving increasing attention as a potential engineering target to improve the performance of Rubisco. However, SSUs are encoded by a family of nuclear rbcS genes in plants, which makes them challenging to engineer and study. Here we have used CRISPR/Cas9 [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9] and T-DNA insertion lines to generate a suite of single and multiple gene knockout mutants for the four members of the rbcS family in Arabidopsis, including two novel mutants 2b3b and 1a2b3b. 1a2b3b contained very low levels of Rubisco (~3% relative to the wild-type) and is the first example of a mutant with a homogenous Rubisco pool consisting of a single SSU isoform (1B). Growth under near-outdoor levels of light demonstrated Rubisco-limited growth phenotypes for several SSU mutants and the importance of the 1A and 3B isoforms. We also identified 1a1b as a likely lethal mutation, suggesting a key contributory role for the least expressed 1B isoform during early development. The successful use of CRISPR/Cas here suggests that this is a viable approach for exploring the functional roles of SSU isoforms in plants., (© Crown copyright. Published by Oxford University Press on behalf of the Society for Experimental Biology.)
- Published
- 2020
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23. The Effect of Refractive Error on Melanopsin-Driven Pupillary Responses.
- Author
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Mutti DO, Mulvihill SP, Orr DJ, Shorter PD, and Hartwick ATE
- Subjects
- Adult, Female, Humans, Light, Male, Pupil radiation effects, Retinal Ganglion Cells metabolism, Young Adult, Hyperopia physiopathology, Myopia physiopathology, Reflex, Pupillary physiology, Rod Opsins metabolism
- Abstract
Purpose: Human and animal studies suggest that light-mediated dopamine release may underlie the protective effect of time outdoors on myopia development. Melanopsin-containing retinal ganglion cells may be involved in this process by integrating ambient light exposure and regulating retinal dopamine levels. The study evaluates this potential involvement by examining whether melanopsin-driven pupillary responses are associated with adult refractive error., Methods: Subjects were 45 young adults (73% female, 24.1 ± 1.8 years) with refractive errors ranging from -6.33 D to +1.70 D. The RAPDx (Konan Medical) pupillometer measured normalized pupillary responses to three forms of square-wave light pulses alternating with darkness at 0.1 Hz: alternating long wavelength (red, peak at 608 nm) and short wavelength (blue, peak at 448 nm), followed by red only and then blue only., Results: Non-myopic subjects displayed greater pupillary constriction in the blue-only condition and slower redilation following blue light offset than subjects with myopia (P = 0.011). Pupillary responses were not significantly different between myopic and non-myopic subjects in the red-only condition (P = 0.15). More hyperopic/less myopic refractive error as a continuous variable was linearly related to larger increases in pupillary constriction in response to blue-only stimuli (r = 0.48, P = 0.001)., Conclusions: Repeated light exposures to blue test stimuli resulted in an adaptation in the pupillary response (more constriction and slower redilation), presumably due to increased melanopsin-mediated input in more hyperopic/less myopic adults. This adaptive property supports a possible role for these ganglion cells in the protective effects of time outdoors on myopia development.
- Published
- 2020
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24. Novel bacterial clade reveals origin of form I Rubisco.
- Author
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Banda DM, Pereira JH, Liu AK, Orr DJ, Hammel M, He C, Parry MAJ, Carmo-Silva E, Adams PD, Banfield JF, and Shih PM
- Subjects
- Phylogeny, Cyanobacteria genetics, Cyanobacteria metabolism, Molecular Structure, Photosynthesis genetics, Photosynthesis physiology, Plant Physiological Phenomena genetics, Ribulose-Bisphosphate Carboxylase genetics, Ribulose-Bisphosphate Carboxylase metabolism
- Abstract
Rubisco sustains the biosphere through the fixation of CO
2 into biomass. In plants and cyanobacteria, form I Rubisco is structurally comprised of large and small subunits, whereas all other Rubisco forms lack small subunits. The rise of the form I complex through the innovation of small subunits represents a key, yet poorly understood, transition in Rubisco's evolution. Through metagenomic analyses, we discovered a previously uncharacterized clade sister to form I Rubisco that evolved without small subunits. This clade diverged before the evolution of cyanobacteria and the origin of the small subunit; thus, it provides a unique reference point to advance our understanding of form I Rubisco evolution. Structural and kinetic data presented here reveal how a proto-form I Rubisco assembled and functioned without the structural stability imparted from small subunits. Our findings provide insight into a key evolutionary transition of the most abundant enzyme on Earth and the predominant entry point for nearly all global organic carbon.- Published
- 2020
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25. Rubisco and carbon-concentrating mechanism co-evolution across chlorophyte and streptophyte green algae.
- Author
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Goudet MMM, Orr DJ, Melkonian M, Müller KH, Meyer MT, Carmo-Silva E, and Griffiths H
- Subjects
- Carbon, Carbon Dioxide, Photosynthesis, Phylogeny, Ribulose-Bisphosphate Carboxylase metabolism, Chlamydomonas reinhardtii genetics, Chlamydomonas reinhardtii metabolism, Chlorophyta metabolism
- Abstract
Green algae expressing a carbon-concentrating mechanism (CCM) are usually associated with a Rubisco-containing micro-compartment, the pyrenoid. A link between the small subunit (SSU) of Rubisco and pyrenoid formation in Chlamydomonas reinhardtii has previously suggested that specific RbcS residues could explain pyrenoid occurrence in green algae. A phylogeny of RbcS was used to compare the protein sequence and CCM distribution across the green algae and positive selection in RbcS was estimated. For six streptophyte algae, Rubisco catalytic properties, affinity for CO
2 uptake (K0.5 ), carbon isotope discrimination (δ13 C) and pyrenoid morphology were compared. The length of the βA-βB loop in RbcS provided a phylogenetic marker discriminating chlorophyte from streptophyte green algae. Rubisco kinetic properties in streptophyte algae have responded to the extent of inducible CCM activity, as indicated by changes in inorganic carbon uptake affinity, δ13 C and pyrenoid ultrastructure between high and low CO2 conditions for growth. We conclude that the Rubisco catalytic properties found in streptophyte algae have coevolved and reflect the strength of any CCM or degree of pyrenoid leakiness, and limitations to inorganic carbon in the aquatic habitat, whereas Rubisco in extant land plants reflects more recent selective pressures associated with improved diffusive supply of the terrestrial environment., (© 2020 The Authors New Phytologist © 2020 New Phytologist Trust.)- Published
- 2020
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26. Photosynthesis across African cassava germplasm is limited by Rubisco and mesophyll conductance at steady state, but by stomatal conductance in fluctuating light.
- Author
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De Souza AP, Wang Y, Orr DJ, Carmo-Silva E, and Long SP
- Subjects
- Carbon Dioxide, Photosynthesis, Plant Breeding, Plant Leaves metabolism, Manihot, Ribulose-Bisphosphate Carboxylase metabolism
- Abstract
Sub-Saharan Africa is projected to see a 55% increase in food demand by 2035, where cassava (Manihot esculenta) is the most widely planted crop and a major calorie source. Yet, cassava yield in this region has not increased significantly for 13 yr. Improvement of genetic yield potential, the basis of the first Green Revolution, could be realized by improving photosynthetic efficiency. First, the factors limiting photosynthesis and their genetic variability within extant germplasm must be understood. Biochemical and diffusive limitations to leaf photosynthetic CO
2 uptake under steady state and fluctuating light in 13 farm-preferred and high-yielding African cultivars were analyzed. A cassava leaf metabolic model was developed to quantify the value of overcoming limitations to leaf photosynthesis. At steady state, in vivo Rubisco activity and mesophyll conductance accounted for 84% of the limitation. Under nonsteady-state conditions of shade to sun transition, stomatal conductance was the major limitation, resulting in an estimated 13% and 5% losses in CO2 uptake and water use efficiency, across a diurnal period. Triose phosphate utilization, although sufficient to support observed rates, would limit improvement in leaf photosynthesis to 33%, unless improved itself. The variation of carbon assimilation among cultivars was three times greater under nonsteady state compared to steady state, pinpointing important overlooked breeding targets for improved photosynthetic efficiency in cassava., (© 2019 The Authors New Phytologist © 2019 New Phytologist Trust.)- Published
- 2020
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27. Hybrid Cyanobacterial-Tobacco Rubisco Supports Autotrophic Growth and Procarboxysomal Aggregation.
- Author
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Orr DJ, Worrall D, Lin MT, Carmo-Silva E, Hanson MR, and Parry MAJ
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Carbon Cycle genetics, Carbon Cycle physiology, Chloroplasts genetics, Chloroplasts metabolism, Chloroplasts ultrastructure, Microscopy, Electron, Transmission, Organelles metabolism, Photosynthesis physiology, Plants, Genetically Modified metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Synechococcus metabolism, Nicotiana growth & development, Nicotiana metabolism, Autotrophic Processes genetics, Carbon Dioxide metabolism, Photosynthesis genetics, Plant Breeding methods, Ribulose-Bisphosphate Carboxylase genetics, Synechococcus genetics, Nicotiana enzymology, Nicotiana genetics
- Abstract
Much of the research aimed at improving photosynthesis and crop productivity attempts to overcome shortcomings of the primary CO
2 -fixing enzyme Rubisco. Cyanobacteria utilize a CO2 -concentrating mechanism (CCM), which encapsulates Rubisco with poor specificity but a relatively fast catalytic rate within a carboxysome microcompartment. Alongside the active transport of bicarbonate into the cell and localization of carbonic anhydrase within the carboxysome shell with Rubisco, cyanobacteria are able to overcome the limitations of Rubisco via localization within a high-CO2 environment. As part of ongoing efforts to engineer a β-cyanobacterial CCM into land plants, we investigated the potential for Rubisco large subunits (LSU) from the β-cyanobacterium Synechococcus elongatus (Se) to form aggregated Rubisco complexes with the carboxysome linker protein CcmM35 within tobacco ( Nicotiana tabacum ) chloroplasts. Transplastomic plants were produced that lacked cognate Se Rubisco small subunits (SSU) and expressed the Se LSU in place of tobacco LSU, with and without CcmM35. Plants were able to form a hybrid enzyme utilizing tobacco SSU and the Se LSU, allowing slow autotrophic growth in high CO2 CcmM35 was able to form large Rubisco aggregates with the Se LSU, and these incorporated small amounts of native tobacco SSU. Plants lacking the Se SSU showed delayed growth, poor photosynthetic capacity, and significantly reduced Rubisco activity compared with both wild-type tobacco and lines expressing the Se SSU. These results demonstrate the ability of the Se LSU and CcmM35 to form large aggregates without the cognate Se SSU in planta, harboring active Rubisco that enables plant growth, albeit at a much slower pace than plants expressing the cognate Se SSU., (© 2020 The authors. All Rights Reserved.)- Published
- 2020
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28. Overexpression of ca1pase Decreases Rubisco Abundance and Grain Yield in Wheat.
- Author
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Lobo AKM, Orr DJ, Gutierrez MO, Andralojc PJ, Sparks C, Parry MAJ, and Carmo-Silva E
- Subjects
- Biomass, Plants, Genetically Modified, Ribulose-Bisphosphate Carboxylase antagonists & inhibitors, Triticum genetics, Triticum growth & development, Phosphoric Monoester Hydrolases metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Triticum enzymology
- Abstract
Rubisco catalyzes the fixation of CO
2 into organic compounds that are used for plant growth and the production of agricultural products, and specific sugar-phosphate derivatives bind tightly to the active sites of Rubisco, locking the enzyme in a catalytically inactive conformation. 2-carboxy-d-arabinitol-1-phosphate phosphatase (CA1Pase) dephosphorylates such tight-binding inhibitors, contributing to the maintenance of Rubisco activity. Here, we investigated the hypothesis that overexpressing ca1pase would decrease the abundance of Rubisco inhibitors, thereby increasing the activity of Rubisco and enhancing photosynthetic performance and productivity in wheat ( Triticum aestivum ). Plants of four independent wheat transgenic lines overexpressing ca1pase showed up to 30-fold increases in ca1pase expression compared to the wild type. Plants overexpressing ca1pase had lower numbers of Rubisco tight-binding inhibitors and higher Rubisco activation state than the wild type; however, there were 17% to 60% fewer Rubisco active sites in the four transgenic lines than in the wild type. The lower Rubisco content in plants overexpressing ca1pase resulted in lower initial and total carboxylating activities measured in flag leaves at the end of the vegetative stage and lower aboveground biomass and grain yield measured in fully mature plants. Hence, contrary to what would be expected, ca1pase overexpression decreased Rubisco content and compromised wheat grain yields. These results support a possible role for Rubisco inhibitors in protecting the enzyme and maintaining an adequate number of Rubisco active sites to support carboxylation rates in planta., (© 2019 The authors.)- Published
- 2019
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29. Extraction of RuBisCO to Determine Catalytic Constants.
- Author
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Orr DJ and Carmo-Silva E
- Subjects
- Blotting, Western, Catalysis, Plant Extracts isolation & purification, Plant Extracts metabolism, Plant Leaves enzymology, Enzyme Assays methods, Photosynthesis, Plant Physiological Phenomena, Ribulose-Bisphosphate Carboxylase isolation & purification, Ribulose-Bisphosphate Carboxylase metabolism
- Abstract
RuBisCO enables net carbon fixation through the carboxylation of RuBP during photosynthesis. Its complex biochemistry and catalytic diversity found among different plants make characterization of RuBisCO properties useful for investigations aimed at improving photosynthetic performance. This chapter reports methods for rapid extraction of soluble proteins to examine RuBisCO catalytic properties, and for large-scale purification of RuBisCO from leaves to measure the specificity of the enzyme toward its gaseous substrates.
- Published
- 2018
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30. Naukan ethnobotany in post-Soviet times: lost edibles and new medicinals.
- Author
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Jernigan KA, Belichenko OS, Kolosova VB, and Orr DJ
- Subjects
- Humans, Plants, Edible, Russia, Ethnobotany, Plants, Medicinal
- Abstract
Background: This study focuses on health-related plant use among speakers of the critically endangered Naukan language (Inuit-Yupik-Unangan family) in the Russian Far East. The Naukan people were forced, in 1958, under Soviet consolidation, to move from their original settlement on Cape Dezhnev, leading to significant changes in spiritual worldview, subsistence, social structure, and language proficiency in the years that followed. Here, we focus on changes that elders report in their edible, medicinal, and spiritual uses of local plant species since their childhood., Methods: The authors worked from 2014 to 2016 in the villages of Lavrentiya, Lorino, and Uelen, in the Chukotskiy district of the Chukotka autonomous region, directly adjacent to the Bering Strait. We conducted structured interviews, using an oral history approach, along with participant observation and collection of voucher specimens from the local arctic tundra. Those with Naukan names and uses represent 42 species in 25 families., Results: Participants reported a decrease of 13% in the number of edible species that people currently harvest, from what they recall harvesting in their youth. On the other hand, the number of local species considered to be medicinal has actually increased by 225%. Current and past Naukan medicinal practices diverge in some notable ways from those of neighboring societies on the Alaskan side of the Bering Strait. Most of the spiritual significance of local plants species is remembered by only a few elders., Conclusions: Naukan elders explained the large increase in use of medicinal plants by noting that their original concept of medicine emphasized prevention and that illnesses were often assigned a spiritual rather than physical cause. Increased integration with ethnic Russians after moving from Naukan led to the adoption not only of new plant uses, but also of an entirely different, more naturalistic way of viewing illness and treatment.
- Published
- 2017
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31. Engineering photosynthesis: progress and perspectives.
- Author
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Orr DJ, Pereira AM, da Fonseca Pereira P, Pereira-Lima ÍA, Zsögön A, and Araújo WL
- Abstract
Photosynthesis is the basis of primary productivity on the planet. Crop breeding has sustained steady improvements in yield to keep pace with population growth increases. Yet these advances have not resulted from improving the photosynthetic process per se but rather of altering the way carbon is partitioned within the plant. Mounting evidence suggests that the rate at which crop yields can be boosted by traditional plant breeding approaches is wavering, and they may reach a "yield ceiling" in the foreseeable future. Further increases in yield will likely depend on the targeted manipulation of plant metabolism. Improving photosynthesis poses one such route, with simulations indicating it could have a significant transformative influence on enhancing crop productivity. Here, we summarize recent advances of alternative approaches for the manipulation and enhancement of photosynthesis and their possible application for crop improvement., Competing Interests: Competing interests: The authors declare that they have no competing interests.No competing interests were disclosed.No competing interests were disclosed.
- Published
- 2017
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32. Uncertainty in measurements of the photorespiratory CO 2 compensation point and its impact on models of leaf photosynthesis.
- Author
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Walker BJ, Orr DJ, Carmo-Silva E, Parry MAJ, Bernacchi CJ, and Ort DR
- Subjects
- Cell Respiration physiology, Plant Leaves metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Temperature, Carbon Dioxide metabolism, Photosynthesis physiology
- Abstract
Rates of carbon dioxide assimilation through photosynthesis are readily modeled using the Farquhar, von Caemmerer, and Berry (FvCB) model based on the biochemistry of the initial Rubisco-catalyzed reaction of net C
3 photosynthesis. As models of CO2 assimilation rate are used more broadly for simulating photosynthesis among species and across scales, it is increasingly important that their temperature dependencies are accurately parameterized. A vital component of the FvCB model, the photorespiratory CO2 compensation point (Γ* ), combines the biochemistry of Rubisco with the stoichiometry of photorespiratory release of CO2 . This report details a comparison of the temperature response of Γ* measured using different techniques in three important model and crop species (Nicotiana tabacum, Triticum aestivum, and Glycine max). We determined that the different Γ* determination methods produce different temperature responses in the same species that are large enough to impact higher-scale leaf models of CO2 assimilation rate. These differences are largest in N. tabacum and could be the result of temperature-dependent increases in the amount of CO2 lost from photorespiration per Rubisco oxygenation reaction.- Published
- 2017
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33. Rubisco small subunits from the unicellular green alga Chlamydomonas complement Rubisco-deficient mutants of Arabidopsis.
- Author
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Atkinson N, Leitão N, Orr DJ, Meyer MT, Carmo-Silva E, Griffiths H, Smith AM, and McCormick AJ
- Subjects
- Amino Acid Sequence, Arabidopsis growth & development, Arabidopsis metabolism, Biocatalysis, Chlorophyll metabolism, Fluorescence, Gene Expression Regulation, Plant, Isoenzymes metabolism, Phenotype, Photosynthesis, Plant Leaves metabolism, Plant Proteins metabolism, Plants, Genetically Modified, Protein Subunits chemistry, RNA, Messenger genetics, RNA, Messenger metabolism, Ribulose-Bisphosphate Carboxylase chemistry, Arabidopsis genetics, Chlamydomonas enzymology, Genetic Complementation Test, Mutation genetics, Protein Subunits metabolism, Ribulose-Bisphosphate Carboxylase metabolism
- Abstract
Introducing components of algal carbon concentrating mechanisms (CCMs) into higher plant chloroplasts could increase photosynthetic productivity. A key component is the Rubisco-containing pyrenoid that is needed to minimise CO
2 retro-diffusion for CCM operating efficiency. Rubisco in Arabidopsis was re-engineered to incorporate sequence elements that are thought to be essential for recruitment of Rubisco to the pyrenoid, namely the algal Rubisco small subunit (SSU, encoded by rbcS) or only the surface-exposed algal SSU α-helices. Leaves of Arabidopsis rbcs mutants expressing 'pyrenoid-competent' chimeric Arabidopsis SSUs containing the SSU α-helices from Chlamydomonas reinhardtii can form hybrid Rubisco complexes with catalytic properties similar to those of native Rubisco, suggesting that the α-helices are catalytically neutral. The growth and photosynthetic performance of complemented Arabidopsis rbcs mutants producing near wild-type levels of the hybrid Rubisco were similar to those of wild-type controls. Arabidopsis rbcs mutants expressing a Chlamydomonas SSU differed from wild-type plants with respect to Rubisco catalysis, photosynthesis and growth. This confirms a role for the SSU in influencing Rubisco catalytic properties., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)- Published
- 2017
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34. Patterns of orofacial clefting in the facial morphology of bats: a possible naturally occurring model of cleft palate.
- Author
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Orr DJ, Teeling EC, Puechmaille SJ, and Finarelli JA
- Subjects
- Animals, Face anatomy & histology, Phylogeny, Chiroptera anatomy & histology, Cleft Palate veterinary, Facial Bones anatomy & histology
- Abstract
A normal feature of the facial anatomy of many species of bat is the presence of bony discontinuities or clefts, which bear a remarkable similarity to orofacial clefts that occur in humans as a congenital pathology. These clefts occur in two forms: a midline cleft between the two premaxillae (analogous to the rare midline craniofacial clefts in humans) and bilateral paramedian clefts between the premaxilla and the maxillae (analogous to the typical cleft lip and palate in humans). Here, we describe the distribution of orofacial clefting across major bat clades, exploring the relationship of the different patterns of clefting to feeding mode, development of the vomeronasal organ, development of the nasolacrimal duct and mode of emission of the echolocation call in different bat groups. We also present the results of detailed radiographic and soft tissue dissections of representative examples of the two types of cleft. The midline cleft has arisen independently multiple times in bat phylogeny, whereas the paramedian cleft has arisen once and is a synapomorphy uniting the Rhinolophidae and Hipposideridae. In all cases examined, the bony cleft is filled in by a robust fibrous membrane, continuous with the periosteum of the margins of the cleft. In the paramedian clefts, this membrane splits to enclose the premaxilla but forms a loose fold laterally between the premaxilla and maxilla, allowing the premaxilla and nose-leaf to pivot dorsoventrally in the sagittal plane under the action of facial muscles attached to the nasal cartilages. It is possible that this is a specific adaptation for echolocation and/or aerial insectivory. Given the shared embryological location of orofacial clefts in bats and humans, it is likely that aspects of the developmental control networks that produce cleft lip and palate in humans may also be implicated in the formation of these clefts as a normal feature in some bats. A better understanding of craniofacial development in bats with and without clefts may therefore suggest avenues for research into abnormal craniofacial development in humans., (© 2016 Anatomical Society.)
- Published
- 2016
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35. Surveying Rubisco Diversity and Temperature Response to Improve Crop Photosynthetic Efficiency.
- Author
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Orr DJ, Alcântara A, Kapralov MV, Andralojc PJ, Carmo-Silva E, and Parry MA
- Subjects
- Biocatalysis, Crops, Agricultural classification, Crops, Agricultural enzymology, Kinetics, Phylogeny, Plant Proteins metabolism, Ribulose-Bisphosphate Carboxylase metabolism, Sequence Analysis, DNA, Species Specificity, Temperature, Crops, Agricultural genetics, Genetic Variation, Photosynthesis genetics, Plant Proteins genetics, Ribulose-Bisphosphate Carboxylase genetics
- Abstract
The threat to global food security of stagnating yields and population growth makes increasing crop productivity a critical goal over the coming decades. One key target for improving crop productivity and yields is increasing the efficiency of photosynthesis. Central to photosynthesis is Rubisco, which is a critical but often rate-limiting component. Here, we present full Rubisco catalytic properties measured at three temperatures for 75 plants species representing both crops and undomesticated plants from diverse climates. Some newly characterized Rubiscos were naturally "better" compared to crop enzymes and have the potential to improve crop photosynthetic efficiency. The temperature response of the various catalytic parameters was largely consistent across the diverse range of species, though absolute values showed significant variation in Rubisco catalysis, even between closely related species. An analysis of residue differences among the species characterized identified a number of candidate amino acid substitutions that will aid in advancing engineering of improved Rubisco in crop systems. This study provides new insights on the range of Rubisco catalysis and temperature response present in nature, and provides new information to include in models from leaf to canopy and ecosystem scale., (© 2016 American Society of Plant Biologists. All Rights Reserved.)
- Published
- 2016
- Full Text
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36. Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis.
- Author
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Prins A, Orr DJ, Andralojc PJ, Reynolds MP, Carmo-Silva E, and Parry MA
- Subjects
- Amino Acids metabolism, Genotype, Kinetics, Models, Biological, Triticum genetics, Biocatalysis, Crops, Agricultural enzymology, Crops, Agricultural physiology, Photosynthesis, Ribulose-Bisphosphate Carboxylase metabolism, Triticum enzymology, Triticum physiology
- Abstract
Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis-Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.)
- Published
- 2016
- Full Text
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37. Epidemiology of orofacial clefts in the East of ireland in the 25-year period 1984-2008.
- Author
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McDonnell R, Owens M, Delany C, Earley M, McGillivary A, Orr DJ, and Duggan L
- Subjects
- Abnormalities, Multiple epidemiology, Adult, Female, Humans, Infant, Newborn, Ireland epidemiology, Male, Maternal Age, Prevalence, Cleft Lip epidemiology, Cleft Palate epidemiology
- Abstract
Objective : To describe the epidemiology of orofacial clefts in the east of Ireland. Design and Setting : A descriptive epidemiologic study on 851 cases of orofacial cleft identified over a 25-year period from 1984 to 2008 from more than 500,000 births. Results : There were 438 (51.5%) cases of cleft lip with or without cleft palate and 413 (48.5%) cases of cleft palate. The total birth prevalence was 16.0 per 10,000 births for all orofacial clefts, 8.2 for cleft lip with or without cleft palate, and 7.8 for cleft palate. Of all cases, 63.7% (542/851) occurred as isolated anomalies, 21.5% (183/851) were associated with multiple anomalies, and 14.8% (126/851) were associated with a syndrome or chromosomal anomaly. A significantly increasing trend over the 25-year period was observed for cleft lip with or without cleft palate associated with syndromes or chromosomal anomalies among mothers younger than 35 years but not in those older than 35 years. Conclusion : A slightly higher rate of orofacial clefts was observed in the east of Ireland than was observed in European and multinational studies during the study period, and there were higher rates of cleft palate. The rising trend in the proportion of mothers aged 35 years or older in Ireland is not contributing significantly to orofacial clefts associated with chromosomal syndromes.
- Published
- 2014
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38. 1H NMR-based metabolomics methods for chemical genomics experiments.
- Author
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Orr DJ, Barding GA Jr, Tolley CE, Hicks GR, Raikhel NV, and Larive CK
- Subjects
- Arabidopsis drug effects, Arabidopsis genetics, Arabidopsis metabolism, Arabidopsis Proteins metabolism, Data Interpretation, Statistical, Genome, Plant, Genomics, Indenes pharmacology, Magnetic Resonance Spectroscopy, Metabolomics, Multivariate Analysis, Principal Component Analysis, Protein Transport, Pyridines pharmacology, Seedlings drug effects, Seedlings metabolism, Seedlings genetics
- Abstract
Metabolomics and chemical genomics studies can each provide unique insights into plant biology. Although a variety of analytical techniques can be used for the interrogation of plant systems, nuclear magnetic resonance (NMR) provides unbiased characterization of abundant metabolites. An example methodology is provided for probing the metabolism of Arabidopsis thaliana in a chemical genomics experiment including methods for tissue treatment, tissue collection, metabolite extraction, and methods to minimize variance in biological and technical sample replicates. Additionally, considerations and methods for data analysis, including multivariate statistics, univariate statistics, and data interpretation are included. The process is illustrated by examining the metabolic effects of chemical treatment of Arabidopsis with Sortin 1, also known as vacuolar protein sorting inhibitor 1. Sortin 1 was applied to Arabidopsis seedlings to examine metabolic effects in a chemical genomics experiment and to demonstrate the utility of metabolomics in conjunction with other "omics" techniques.
- Published
- 2014
- Full Text
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39. Socioeconomic deprivation does not affect prescribing of secondary prevention in patients with peripheral arterial disease.
- Author
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Park JH, Ruiz MC, Shields D, and Orr DJ
- Subjects
- Aged, Cardiovascular Agents economics, Comorbidity, Drug Prescriptions, Drug Utilization Review trends, Female, Humans, Life Style, Male, Middle Aged, Peripheral Arterial Disease diagnosis, Peripheral Arterial Disease economics, Peripheral Arterial Disease epidemiology, Practice Patterns, Physicians' economics, Referral and Consultation, Retrospective Studies, Risk Factors, Scotland epidemiology, Secondary Prevention economics, Smoking adverse effects, Smoking epidemiology, Treatment Outcome, Cardiovascular Agents therapeutic use, Peripheral Arterial Disease drug therapy, Poverty, Practice Patterns, Physicians' trends, Secondary Prevention trends, Social Class, Socioeconomic Factors
- Abstract
Aim: Aim of the study was to assess the effect of socioeconomic deprivation on prescribing of cardiovascular secondary prevention medications in patients referred with peripheral arterial disease (PAD)., Methods: A retrospective review of vascular clinic referrals was performed. All patients referred from primary care with suspected PAD over a two month period were included. The deprivation score, prescription of cardiovascular secondary prevention medications, smoking status and the presence of cardiovascular co-morbidities (coronary artery or cerebrovascular disease--CAD/CVD) were assessed. Comparison was made between socioeconomic groups using the Carstairs Deprivation (DepCat) Score and between patients with and without a history of currently existing cardiovascular co-morbidities., Results: The study included 391 patients. Almost two thirds of patients (253) were from the most deprived socioeconomic groups and were significantly younger at presentation (median age DepCat 7: 63 yrs, DepCat 1-2: 74.5 yrs, P<0.0001). The majority of patients with a prior history of CAD/CVD were prescribed secondary preventative medications at the time of referral with suspected PAD whereas those with no prior history of CAD/CVD, (212 patients, 54%) were significantly less likely to be prescribed antiplatelets (47% vs. 83%), statins (45% vs. 86%) or ACEi/ARBs (29% vs. 68%) (all P<0.05). Secondary prevention prescribing did not differ between socioeconomic groups., Conclusion: Secondary prevention prescribing is inadequate in patients with suspected PAD regardless of socioeconomic group and is significantly lower in those without previously diagnosed CAD/CVD. There remains a lack of appreciation of the high cardiovascular risk associated with PAD.
- Published
- 2013
40. VIZR--an automated chemometric technique for metabolic profiling.
- Author
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Barding GA Jr, Orr DJ, Sathnur SM, and Larive CK
- Subjects
- Alcoholic Beverages analysis, Analgesics, Non-Narcotic pharmacology, Female, Humans, Ibuprofen pharmacology, Male, Magnetic Resonance Spectroscopy methods, Metabolome drug effects, Metabolomics methods, Urinalysis methods
- Abstract
A chemometric technique, visual interpretation of z-score ratios (VIZR), written in the open source code R, has been developed to identify metabolic differences between individual biosamples and a control group. To demonstrate the capabilities of VIZR, 49 urine samples were collected from healthy volunteers: 41 samples were collected randomly following a normal dietary routine and 7 test samples were collected after dietary supplementation with either ibuprofen or alcoholic beverages. An eighth test sample was prepared by 50% dilution of a control sample. Sample analysis was conducted by (1)H nuclear magnetic resonance (NMR) spectroscopy and the collected data were subjected to VIZR analysis, which successfully discriminated each of the 8 test samples from the 41 control samples. In addition, VIZR analysis revealed the NMR spectral regions responsible for the disparity between the individual test samples and the control group. The self-normalizing nature of the VIZR calculation provides a robust analysis independent of dilution effects, which is especially important in urine analyses. Potential applications of VIZR include high-throughput data analysis for toxicological profiling, disease diagnosis, and biomarker identification in any type of biosample for which a control dataset can be established. Although demonstrated herein for the statistical analysis of (1)H NMR data, the VIZR program is platform independent and could be applied to digitized metabolic datasets acquired using other techniques including hyphenated mass spectrometry measurements.
- Published
- 2013
- Full Text
- View/download PDF
41. An unusual exit point from an electrocution injury.
- Author
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Davidson CC and Orr DJ
- Subjects
- Burns, Electric pathology, Humans, Male, Tooth Injuries therapy, Young Adult, Accidents, Occupational, Burns, Electric complications, Incisor, Tooth Injuries etiology
- Published
- 2010
- Full Text
- View/download PDF
42. Pharmacotherapy to improve outcomes in infrainguinal bypass graft surgery: a review of current treatment strategies.
- Author
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Jackson AJ, Coats P, Orr DJ, Teenan RP, and Wadsworth RM
- Subjects
- Combined Modality Therapy, Evidence-Based Medicine, Humans, Peripheral Vascular Diseases physiopathology, Practice Guidelines as Topic, Time Factors, Treatment Outcome, Vascular Patency drug effects, Cardiovascular Agents therapeutic use, Lower Extremity blood supply, Peripheral Vascular Diseases drug therapy, Peripheral Vascular Diseases surgery, Vascular Surgical Procedures, Veins transplantation
- Abstract
A total of 12,000 infrainguinal bypass grafts are performed annually in the United Kingdom, with outcomes suboptimal: 20% of above-knee vein grafts require intervention by 3 years. Transatlantic Inter-Society Consensus (TASC) guidelines exist on pharmacological management of peripheral vascular disease patients, however, little is recommended regarding optimum pharmacological management following revascularization to improve graft patency. The current recommendation is that all patients are on an antiplatelet agent following bypass grafting, the only intervention with significant evidence supporting use. This article will review pharmacological strategies aimed at improving the survival of infrainguinal vein grafts and the current evidence base for their use., (Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
43. Unnecessary inter-hospital referral of minor hand injuries: a continuing problem.
- Author
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Murphy SM, Whately K, Eadie PA, and Orr DJ
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Female, Humans, Injury Severity Score, Male, Middle Aged, Prospective Studies, Retrospective Studies, Severity of Illness Index, Young Adult, Hand Injuries surgery, Health Services Needs and Demand, Interinstitutional Relations, Patient Transfer, Referral and Consultation statistics & numerical data
- Abstract
Background: Trauma patients are a burden on resources in terms of personnel, operating time and bed occupancy. The plastic surgery trauma clinic was established in January 1999 and has been running Monday to Friday mornings from 9 am to 1 pm since its establishment., Aim: To analyse and compare referral patterns to the Plastic Surgery trauma clinic over three time periods., Method: Three time groups were analysed and compared: data from this initial study (2000-2001), a retrospective chart review (2002-2003), as well as a prospective study (2006-2007)., Results: Numbers of attendances at the Trauma Clinic seem to be increasing every year despite encouragement by letter after the initial study for local centres to treat many of the minor injuries not requiring plastic surgical skills., Conclusion: Admission rates have remained below 50% of the patients seen in the clinic; however 50% of patients required only local anaesthetic procedures performed in the clinic, or no treatment at all (27.6% of patients in 2003, 35.3% in 2006).
- Published
- 2010
- Full Text
- View/download PDF
44. Testing reported associations of genetic risk factors for oral clefts in a large Irish study population.
- Author
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Carter TC, Molloy AM, Pangilinan F, Troendle JF, Kirke PN, Conley MR, Orr DJ, Earley M, McKiernan E, Lynn EC, Doyle A, Scott JM, Brody LC, and Mills JL
- Subjects
- Female, Gene Frequency, Genotype, Humans, Infant, Newborn, Ireland epidemiology, Male, Pregnancy, Risk Factors, Cleft Lip epidemiology, Cleft Lip genetics, Cleft Palate epidemiology, Cleft Palate genetics, Genetic Predisposition to Disease
- Abstract
Background: Suggestive, but not conclusive, studies implicate many genetic variants in oral cleft etiology. We used a large, ethnically homogenous study population to test whether reported associations between nonsyndromic oral clefts and 12 genes (CLPTM1, CRISPLD2, FGFR2, GABRB3, GLI2, IRF6, PTCH1, RARA, RYK, SATB2, SUMO1, TGFA) could be confirmed., Methods: Thirty-one single nucleotide polymorphisms (SNPs) in exons, splice sites, and conserved non-coding regions were studied in 509 patients with cleft lip with or without cleft palate (CLP), 383 with cleft palate only (CP), 838 mothers and 719 fathers of patients with oral clefts, and 902 controls from Ireland. Case-control and family-based statistical tests were performed using isolated oral clefts for the main analyses., Results: In case-control comparisons, the minor allele of PTCH1 A562A (rs2066836) was associated with reduced odds of CLP (odds ratios [OR], 0.29; 95% confidence interval [CI], 0.13-0.64 for homozygotes), whereas the minor allele of PTCH1 L1315P (rs357564) was associated with increased odds of CLP (OR, 1.36; 95% CI, 1.07-1.74 for heterozygotes; and OR, 1.56; 95% CI, 1.09-2.24 for homozygotes). The minor allele of one SUMO1 SNP, rs3769817 located in intron 2, was associated with increased odds of CP (OR, 1.45; 95% CI, 1.06-1.99 for heterozygotes). Transmission disequilibrium was observed for the minor allele of TGFA V159V (rs2166975) which was over-transmitted to CP cases (p = 0.041)., Conclusions: For 10 of the 12 genes, this is the largest candidate gene study of nonsyndromic oral clefts to date. The findings provide further evidence that PTCH1, SUMO1, and TGFA contribute to nonsyndromic oral clefts.
- Published
- 2010
- Full Text
- View/download PDF
45. Occupational injuries in foreign-national workers presenting to St James's Hospital Plastic Surgery service.
- Author
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Davidson CC and Orr DJ
- Subjects
- Adolescent, Adult, Aged, Female, Humans, Ireland epidemiology, Male, Middle Aged, Occupational Health, Prospective Studies, Risk Factors, Young Adult, Accidents, Occupational statistics & numerical data, Occupational Diseases epidemiology, Surgery, Plastic statistics & numerical data, Transients and Migrants statistics & numerical data
- Abstract
This study was undertaken to investigate our impression that migrant foreign-national workers were more at risk of sustaining work place injuries requiring referral to our Plastic Surgery service than their indigenous Irish counterparts. Data were collected prospectively from August 2006 to February 2007 on all work-related injuries presenting to the Plastic Surgery service in St James's Hospital, Dublin. 201 work-related injuries were recorded during the six month study period. 40% (n = 81) of the study group were foreign-national workers. Foreign-national workers account for only nine percent of the total Irish workforce. 31% (n = 25) of the study group required a translator. Over half (55%) of all the foreign-national workers in the current study had been in their present job for less than six months at the time of injury compared to only nine percent of Irish workers. This study highlights that foreign-national workers in Ireland are at a disproportionately high risk of occupational injury when compared to their Irish colleagues and emphasises the need for targeted occupational health and safety measures in this vulnerable group.
- Published
- 2009
46. Folate-related gene polymorphisms as risk factors for cleft lip and cleft palate.
- Author
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Mills JL, Molloy AM, Parle-McDermott A, Troendle JF, Brody LC, Conley MR, Cox C, Pangilinan F, Orr DJ, Earley M, McKiernan E, Lynn EC, Doyle A, Scott JM, and Kirke PN
- Subjects
- Amino Acid Substitution genetics, Case-Control Studies, Child, Cleft Lip enzymology, Cleft Lip metabolism, Cleft Palate enzymology, Cleft Palate metabolism, Female, Folic Acid genetics, Humans, Male, Methylenetetrahydrofolate Reductase (NADPH2) genetics, Multicenter Studies as Topic, Pregnancy, Risk Factors, Cleft Lip genetics, Cleft Palate genetics, Folic Acid metabolism, Genetic Predisposition to Disease, Polymorphism, Single Nucleotide
- Abstract
Background: Cleft lip with or without cleft palate (CLP) and cleft palate only (CPO) have an inherited component and, many studies suggest, a relationship with folate. Attempts to find folate-related genes associated with clefts have, however, often been inconclusive. This study examined four SNPs related to folate metabolism (MTHFR 677 C-->T, MTHFR 1298 A-->C, MTHFD1 1958 G-->A, and TC II 776 C-->G) in a large Irish population to clarify their relationship with clefts., Methods: Cases and their parents were recruited from major surgical centers performing cleft repairs in Ireland and a support organization. Data on risk factors, medical history, and DNA were collected. Controls were pregnant women from the greater Dublin area (n = 1,599)., Results: CLP cases numbered 536 and CPO cases 426 after exclusions. CPO mothers were significantly more likely than controls to be MTHFR 677 TT, OR 1.50 (95% CI: 1.05-2.16; p = .03). Log-linear analysis showed a borderline association (p = .07). Isolated CPO case mothers were significantly more likely than controls to be homozygous for the MTHFD1 1958 G-->A variant, OR 1.50 (95%CI: 1.08-2.09; p = .02). When multiple cases were added, both CPO cases and case mothers were significantly more likely to be AA (p = .02 and p = .007, respectively). The CLP case-control and mother-control analyses also showed significant effects, ORs 1.38 (95% CI: 1.05-1.82; p = .03) and 1.39 (95% CI: 1.04-1.85; p = .03), respectively., Conclusions: Associations were found for both CPO and CLP and MTHFD1 1958 G-->A in cases and case mothers. MTHFR 677 C-->T could be a maternal risk factor for clefts but the association was not strong. Because multiple comparisons were made, these findings require additional investigation. Given the known association between MTHFD1 1958 G-->A and NTDs, these findings should be explored in more detail., ((c) 2008 Wiley-Liss, Inc.)
- Published
- 2008
- Full Text
- View/download PDF
47. Intraoperative retrograde mesenteric angioplasty for acute occlusive mesenteric ischaemia: a case series.
- Author
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Moyes LH, McCarter DHA, Vass DG, and Orr DJ
- Subjects
- Adult, Aged, Angioplasty, Balloon instrumentation, Female, Humans, Ischemia diagnostic imaging, Ischemia etiology, Ischemia mortality, Ischemia surgery, Ligation, Male, Mesenteric Artery, Superior surgery, Mesenteric Vascular Occlusion complications, Mesenteric Vascular Occlusion diagnostic imaging, Mesenteric Vascular Occlusion mortality, Mesenteric Vascular Occlusion surgery, Middle Aged, Radiography, Reoperation, Stents, Time Factors, Treatment Outcome, Vascular Surgical Procedures, Angioplasty, Balloon methods, Digestive System Surgical Procedures, Intestines blood supply, Ischemia therapy, Mesenteric Vascular Occlusion therapy
- Abstract
Acute mesenteric ischaemia secondary to atherosclerotic disease of the superior mesenteric artery is a surgical emergency associated with a poor prognosis, and requires prompt diagnosis and early revascularisation in order to improve outcome. The traditional management of surgical resection of necrotic bowel plus mesenteric revascularisation by surgical bypass is associated with significant morbidity and mortality. We describe the use of a combined surgical and endovascular approach, using intraoperative retrograde superior mesenteric angioplasty at the time of laparotomy. Four patients have been treated by this combined technique with three surviving, although one subsequently required an open surgical revascularisation procedure.
- Published
- 2008
- Full Text
- View/download PDF
48. The use of clopidogrel in carotid endarterectomy: an audit of current practice.
- Author
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Jackson AJ, Teenan RP, and Orr DJ
- Subjects
- Cerebrovascular Disorders etiology, Clopidogrel, Hemorrhage chemically induced, Humans, Practice Guidelines as Topic, Practice Patterns, Physicians', Surveys and Questionnaires, Ticlopidine adverse effects, Ticlopidine therapeutic use, Aspirin therapeutic use, Cerebrovascular Disorders prevention & control, Endarterectomy, Carotid adverse effects, Medical Audit, Platelet Aggregation Inhibitors therapeutic use, Ticlopidine analogs & derivatives
- Abstract
Clopidogrel is commonly encountered in patients presenting for carotid endarterectomy (CEA). Its use around this time is controversial and there is no randomized control trial data to determine best practice. Questionnaires were posted to all members of the Vascular Society investigating clopidogrel use at the time of CEA. 52% discontinue clopidogrel preoperatively, with 51% of those using no alternative and 49% replacing it with aspirin. Clopidogrel use is not related to the number of endarterectomies performed by each surgeon. There is no consensus on clopidogrel use during CEA. This highlights the need for quality prospective data on this subject.
- Published
- 2007
- Full Text
- View/download PDF
49. Tall toddlers--at increased risk for scalds?
- Author
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Murphy SM, Murray D, Rooney K, and Orr DJ
- Subjects
- Accidents, Home, Body Surface Area, Child, Preschool, Environment Design, Female, Humans, Infant, Male, Risk Factors, Body Height, Burns etiology
- Published
- 2004
- Full Text
- View/download PDF
50. Severe acute hepatitis in a burns patient.
- Author
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Nugent N, McCormick PA, and Orr DJ
- Subjects
- Acute Disease, Burns blood, Burns therapy, Chemical and Drug Induced Liver Injury blood, Chemical and Drug Induced Liver Injury therapy, Humans, Male, Middle Aged, Treatment Outcome, Burns complications, Chemical and Drug Induced Liver Injury etiology, Herbicides poisoning, Paraquat poisoning
- Published
- 2004
- Full Text
- View/download PDF
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