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Aboelmagd SM, Low SB, Cahir JG, Loveday D, Marshall AT, Teh J, Vaughan P, Grainger A, MacGregor A, Toms AP. The Norwich Osteoarthritis of the Ankle MRI Score (NOAMS): a reliability study. Clin Radiol 2022; 77:e449-e457. [PMID: 35367050 DOI: 10.1016/j.crad.2022.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 02/24/2022] [Indexed: 11/30/2022]
Abstract
AIM To define and test the inter- and intra-rater reliability of a grading system for staging osteoarthritis (OA) of the ankle with magnetic resonance imaging (MRI) (Norwich Osteoarthritis of the Ankle MRI Score, NOAMS). MATERIALS AND METHODS The MRI features to be included in the score were defined by a multidisciplinary expert panel through a Delphi process. An anonymised randomised dataset of 50 MRI studies was created from patients with concurrent plain radiographs to include 10 ankles of each of the Kellgren-Lawrence grades 0 to 4. Two experienced musculoskeletal radiologists and two trainees scored each ankle MRI twice independently and blinded to the plain radiographs. RESULTS The inter-rater kappa coefficient of agreement for cartilage disease was 0.88 (95% confidence interval [CI]: 0.85, 0.91) for experienced raters and 0.71 (95% CI: 0.67, 0.76) for trainees. Inter-rater agreement for subchondral bone marrow oedema and cysts varied from 0.73 to 0.82 for experienced raters and from 0.63 to 0.75 for trainees with lowest 95% CI of 0.48 and 0.63. When bone marrow lesions were combined into a total joint score the level of agreement increased to between 0.88 and 0.97 with lowest 95% CI of 0.86. Combining cartilage zone scores did not increase the reliability coefficients. CONCLUSION An expert panel considered that cartilage degradation and subchondral bone marrow lesions were the most important features for staging the severity of ankle OA on MRI. Experienced observers can grade the severity of ankle OA on MRI with a clinically useful high degree of reproducibility.
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Affiliation(s)
- S M Aboelmagd
- Department of Radiology, Royal Devon and Exeter NHS Trust, UK
| | - S B Low
- Department of Radiology, Norfolk & Norwich University Hospital, UK
| | - J G Cahir
- Department of Radiology, Norfolk & Norwich University Hospital, UK
| | - D Loveday
- Department of Orthopaedic Surgery, Norfolk & Norwich University Hospital, UK
| | - A T Marshall
- Department of Rheumatology, Norfolk & Norwich University Hospital, UK
| | - J Teh
- Department of Radiology, Nuffield Orthopaedic Centre, Oxford, UK
| | - P Vaughan
- Department of Trauma and Orthopaedics, West Suffolk Hospital, Bury St Edmunds, UK
| | - A Grainger
- Department of Radiology, Addenbrooke's Hospital, Cambridge, UK
| | - A MacGregor
- Norwich Medical School, University of East Anglia, UK
| | - A P Toms
- Department of Radiology, Addenbrooke's Hospital, Cambridge, UK; Norwich Medical School, University of East Anglia, UK; NIHR Cambridge Biomedical Research Centre, Cambridge, UK.
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Vaughan P, Greening N, Oey I, Rathinam S, Waller D. O-013 * AN INDIVIDUALIZED RISK MODEL OF MORTALITY FOLLOWING LUNG VOLUME REDUCTION SURGERY. Interact Cardiovasc Thorac Surg 2014. [DOI: 10.1093/icvts/ivu167.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
Limited forefoot amputation in diabetic patients with osteomyelitis is frequently required. We retrospectively reviewed diabetic patients with osteomyelitis, an unhealed ulcer and blood pressure in the toe of > 45 mmHg who underwent limited amputation of the foot with primary wound closure. Between 2006 and 2012, 74 consecutive patients with a mean age of 67 years (29 to 93), and a median follow-up of 31 months, were included. All the wounds healed primarily at a median of 37 days (13 to 210; mean 48). At a median of 6 months (1.5 to 18; mean 353 days), 23 patients (31%) suffered a further ulceration. Of these, 12 patients (16% of the total) required a further amputation. We conclude that primary wound closure following limited amputation of the foot in patients with diabetes is a safe and effective technique when associated with appropriate antibiotic treatment. Cite this article: Bone Joint J 2013;95-B:1083–7.
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Affiliation(s)
- N. Shaikh
- Addenbrooke’s Hospital, Orthopaedic
Department, Cambridge University Hospitals NHS
Foundation Trust, Cambridge, UK
| | - P. Vaughan
- Addenbrooke’s Hospital, Orthopaedic
Department, Cambridge University Hospitals NHS
Foundation Trust, Cambridge, UK
| | - K. Varty
- Addenbrooke’s Hospital, Vascular
Unit, Cambridge University Hospitals NHS Foundation
Trust, Cambridge, UK
| | - A. P. Coll
- Addenbrooke’s Hospital, Wolfson
Diabetes and Endocrine Clinic, Cambridge University
Hospitals NHS Foundation Trust, Cambridge, UK
| | - A. H. N. Robinson
- Addenbrooke’s Hospital, Orthopaedic
Department, Cambridge University Hospitals NHS
Foundation Trust, Cambridge, UK
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Howard LS, Crosby A, Vaughan P, Sobolewski A, Southwood M, Foster ML, Chilvers ER, Morrell NW. Distinct responses to hypoxia in subpopulations of distal pulmonary artery cells contribute to pulmonary vascular remodeling in emphysema. Pulm Circ 2012; 2:241-9. [PMID: 22837865 PMCID: PMC3401878 DOI: 10.4103/2045-8932.97616] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We have shown previously that hypoxia inhibits the growth of distal human pulmonary artery smooth muscle cells (PASMC) isolated under standard normoxic conditions (PASMC(norm)). By contrast, a subpopulation of PASMC, isolated through survival selection under hypoxia was found to proliferate in response to hypoxia (PASMC(hyp)). We sought to investigate the role of hypoxia-inducible factor (HIF) in these differential responses and to assess the relationship between HIF, proliferation, apoptosis, and pulmonary vascular remodeling in emphysema. PASMC were derived from lobar resections for lung cancer. Hypoxia induced apoptosis in PASMC(norm) (as assessed by TUNEL) and mRNA expression of Bax and Bcl-2, and induced proliferation in PASMC(hyp) (as assessed by (3)H-thymidine incorporation). Both observations were mimicked by dimethyloxallyl glycine, a prolyl-hydroxylase inhibitor used to stabilize HIF under normoxia. Pulmonary vascular remodeling was graded in lung samples taken from patients undergoing lung volume reduction surgery for severe heterogenous emphysema. Carbonic anhydrase IX expression in the medial compartment was used as a surrogate of medial hypoxia and HIF stabilization and increased with increasing vascular remodeling. In addition, a mixture of proliferation, assessed by proliferating-cell nuclear antigen, and apoptosis, assessed by active caspase 3 staining, were both higher in more severely remodeled vessels. Hypoxia drives apoptosis and proliferation via HIF in distinct subpopulations of distal PASMC. These differential responses may be important in the pulmonary vascular remodeling seen in emphysema and further support the key role of HIF in hypoxic pulmonary hypertension.
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Affiliation(s)
- L S Howard
- National Pulmonary Hypertension Service (London), Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK
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Slater S, Crawford MJ, Kabbouche MA, LeCates SL, Cherney S, Vaughan P, Segers A, Manning P, Burdine D, Powers SW, Hershey AD. Effects of Gender and Age on Paediatric Headache. Cephalalgia 2009; 29:969-73. [DOI: 10.1111/j.1468-2982.2008.01827.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this study was to evaluate the impact of gender and age on headache characteristics and disability. Headache characteristics were assessed at an initial visit to a paediatric specialty care centre and five follow-up visits. A total number of 4121 patients were evaluated. Fifty-eight per cent of the sample was female. Boys were younger at their first headache and initial visit. They more frequently described headache pain as squeezing and location as top of the head. Girls reported more frequent and longer headaches. Girls more often described headache pain as sharp and location as back of the head. Age accounted for more variance than gender in headache severity, duration, frequency and disability. Gender differences exist in headache characteristics. Age is also an important factor in the variability in characteristics and disability. Longitudinal studies are needed to describe further the natural history of headaches in childhood and compare outcome between genders.
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Affiliation(s)
- S Slater
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center
| | - MJ Crawford
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center
| | - MA Kabbouche
- Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - SL LeCates
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - S Cherney
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - P Vaughan
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - A Segers
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - P Manning
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - D Burdine
- Division of Neurology, Cincinnati Children's Hospital Medical Center
| | - SW Powers
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center
- Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - AD Hershey
- Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
- Division of Neurology, Cincinnati Children's Hospital Medical Center
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Waqar S, Vaughan P, Sarkar P. Bilateral pneumothoraces treated with a single chest drain. Br J Hosp Med (Lond) 2009; 70:359. [PMID: 19516218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Resolution of bilateral pneumothoraces with a single chest drain is seldom seen in clinical practice. A 76-year-old man underwent coronary artery bypass grafting following which he developed bilateral pneumothoraces.
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Affiliation(s)
- S Waqar
- Department of Cardiothoracis Surgery, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield
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Vaughan P, Waqar S, Morgan-Hughes N, Edwards J. French window thoracotomy: a case-control study of lung resection via a novel non-rib spreading thoracotomy. Lung Cancer 2009. [DOI: 10.1016/s0169-5002(09)70106-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Vaughan P, Marks R, Sarkar P. The dangers of toothpicking. Emerg Med J 2008; 25:509. [PMID: 18660403 DOI: 10.1136/emj.2007.054940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- P Vaughan
- Department of Cardiothoracic Surgery, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
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Abstract
OBJECTIVES The relation between complicated early childhood convulsion (ECC) and adult epilepsy is unclear, although a history of complicated ECC is obtainable in half of adults with epilepsy associated with hippocampal sclerosis. It is not known if the ECC is a marker of pre-existing brain damage or is itself harmful to the developing brain. The objective of the study was to assess the extent of structural brain abnormality present soon after a first complicated early childhood convulsion with a view to obtaining data which might contribute to an understanding of whether such abnormalities were likely to be pre-existing or caused by the convulsion. METHODS Children under the age of 5 years were recruited into the study after their first complicated febrile or non-febrile ECC. None had previously experienced an epileptic seizure. All underwent MRI of the brain within 14 days. Hippocampal volumes and T2 relaxation times were measured. The results were compared with a neurological control group of children without gross structural abnormalities of the neocortex undergoing MRI of the brain for reasons other than epilepsy. RESULTS Eighteen patients and 10 control subjects were recruited into the study. One patient was subsequently excluded because of EEG and clinical evidence of benign childhood epilepsy. Nine patients had volumetric evidence of significant hippocampal volume asymmetry (3 SD from the mean of the control group), although in only three of these was the asymmetry apparent on visual inspection of the MRI. Three patients had extrahippocampal neuropathology. None of the control subjects had significant hippocampal volume asymmetry (p<0.001). T2 relaxometry showed no evidence that postictal hippocampal oedema contributed to the asymmetry. CONCLUSIONS There is a high prevalence of structural brain abnormalities in children within 2 weeks of the first complicated early childhood convulsion, including significant hippocampal asymmetry unrelated to oedema. This does not exclude a damaging effect of complicated ECC on the brain, but suggests that in at least some patients the complicated ECC is the result of pre-existing brain abnormalities.
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Affiliation(s)
- R A Grünewald
- Section of Clinical Neurology, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, UK.
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Leahy M, Vaughan P, Fanning L, Fanning S, Sheehan D. Purification and some characteristics of a recombinant dimeric rhizobium meliloti beta-galactosidase expressed in escherichia coli. Enzyme Microb Technol 2001; 28:682-688. [PMID: 11339953 DOI: 10.1016/s0141-0229(01)00314-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A recombinant Rhizobium meliloti beta-galactosidase was purified to homogeneity from an Escherichia coli expression system. The gene for the enzyme was cloned into a pKK223-3 plasmid which was then used to transform E. coli JM109 cells. The enzyme was purified 35-fold with a yield of 34% by a combination of DEAE-cellulose (pH 8.0) and two sequential Mono Q steps (at pH 8.0 and 6.0, respectively). The purified enzyme had an apparent molecular mass of 174 kDa and a subunit molecular weight of 88 kDa, indicating that it is a dimer. It was active with both synthetic substrates p-nitrophenyl beta-D-galactopyranoside (PNPG) and o-nitrophenyl beta-D-galactopyranoside (ONPG) with K(m)(PNPG) and K(m)(ONPG) of 1 mM at 25 degrees C. The k(cat)/K(m) ratios for both substrates were approximately 70 mM(-1) sec(-1), indicating no clear preference for either PNPG or ONPG, unlike E. coli beta-galactosidase. After non-denaturing electrophoresis, active beta-galactosidase bands were identified using 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-gal) or 6-bromo-2-naphthyl beta-D-galactopyranoside (BNG) and diazo blue B.
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Affiliation(s)
- M Leahy
- Department of Biochemistry, Lee Maltings, Prospect Row, Mardyke, Cork, Ireland
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16
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O'Donnell KA, Tighe O, O'Neill C, Naughten E, Mayne PD, McCarthy TV, Vaughan P, Croke DT. Rapid detection of the R408W and I65T mutations in phenylketonuria by glycosylase mediated polymorphism detection. Hum Mutat 2001; 17:432. [PMID: 11317360 DOI: 10.1002/humu.1120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mutation detection methods based upon chemical or enzymatic cleavage of DNA offer excellent detection efficiencies coupled with high throughput and low unit cost. We describe the application of the novel technique of Glycosylase Mediated Polymorphism Detection (GMPD) to the detection of two of the most common mutations of the PAH gene in the Irish population that cause phenylketonuria (PKU), R408W and I65T, which occur at relative frequencies of 41.0% and 10.4% respectively. GMPD assays for R408W and I65T were developed permitting fluorescent detection of cleavage products on the ALFexpresstrade mark automated DNA sequencer. The method was validated by screening a panel of PKU patients whose mutant genotypes had previously been characterised by standard methods. It also proved possible to perform multiplex detection of the two mutations by co-electrophoresis of GMPD products. GMPD is a rapid and robust method for the detection of the R408W and I65T mutations, whose key advantage lies in its use of a pair of enzymes with high cleavage efficiency to detect a number of mutations as compared to the use of individual digestions with a range of specific restriction endonuclease enzymes. Hum Mutat 17:432, 2001.
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Affiliation(s)
- K A O'Donnell
- Department of Pathology, The Children's Hospital, Temple Street, Dublin 1, Republic of Ireland
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Vaughan P. Use of uracil DNA glycosylase in the detection of known DNA mutations and polymorphisms. Glycosylase-mediated polymorphism detection (GMPD-check). Methods Mol Biol 2001; 152:169-77. [PMID: 10957977 DOI: 10.1385/1-59259-068-3:169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Vaughan P. Use of uracil DNA glycosylase in scanning for unknown DNA mutations and polymorphisms. Glycosylase-mediated polymorphism detection (GMPD-scan). Methods Mol Biol 2001; 152:179-86. [PMID: 10957978 DOI: 10.1385/1-59259-068-3:179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Chantornvong S, Collin J, Dodgson R, Lee K, McCargo D, Seddon D, Vaughan P, Woelk G. Political economy of tobacco control in low-income and middle-income countries: lessons from Thailand and Zimbabwe. Global Analysis Project Team. Bull World Health Organ 2000; 78:913-9. [PMID: 10994265 PMCID: PMC2560812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Crucial to the success of the proposed Framework Convention on Tobacco Control will be an understanding of the political and economic context for tobacco control policies, particularly in low-income and middle-income countries. Policy studies in Thailand and Zimbabwe employed the analytical perspective of political economy and a research strategy that used political mapping, a technique for characterizing and evaluating the political environment surrounding a policy issue, and stakeholder analysis, which seeks to identify key actors and to determine their capacity to shape policy outcomes. These policy studies clearly revealed how tobacco control in low-income and middle-income countries is also being shaped by developments in the global and regional political economy. Hence efforts to strengthen national control policies need to be set within the context of globalization and the international context. Besides the transnational tobacco companies, international tobacco groups and foreign governments, international agencies and nongovernmental organizations are also playing influential roles. It cannot be assumed, therefore, that the tobacco control strategies being implemented in industrialized countries will be just as effective and appropriate when implemented in developing countries. There is an urgent need to expand the number of such tobacco policy studies, particularly in low-income and middle-income countries. Comprehensive guidelines for tobacco policy analysis and research are required to support this process, as is a broader international strategy to coordinate further tobacco policy research studies at country, regional and global levels.
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Abstract
During the last decade the planning of services for offenders with mental disorders in the United Kingdom has been geared toward diverting them from the criminal justice system to appropriate levels of psychiatric and social care. Although a seamless service system is yet to be developed, the central government has made a concerted effort to promote a better understanding of the needs of offenders with mental disorders and encourage collaboration between the relevant agencies. A major program of research has been initiated, and local health authorities have been encouraged to use a consortium approach to planning and delivery of specialist services. The authors discuss the activities of the Wessex consortium, composed of five local health authorities and a social services department serving a catchment area with a population of 2.5 million in southern England. The consortium has commissioned needs assessments for all offenders with mental illness from the catchment area and a survey of the resources for secure residential treatment in the region. Based on data from this research, the consortium is planning the development of two long-stay secure units to accommodate offenders with a history of repeated inpatient and prison stays and poor response to previous treatment and rehabilitation efforts.
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Affiliation(s)
- D Badger
- Department of Professional Education in Community Studies, University of Reading, Earley, Reading, England.
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Lynch PJ, Tong J, Lehane M, Mallet A, Giblin L, Heffron JJ, Vaughan P, Zafra G, MacLennan DH, McCarthy TV. A mutation in the transmembrane/luminal domain of the ryanodine receptor is associated with abnormal Ca2+ release channel function and severe central core disease. Proc Natl Acad Sci U S A 1999; 96:4164-9. [PMID: 10097181 PMCID: PMC22438 DOI: 10.1073/pnas.96.7.4164] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Central core disease is a rare, nonprogressive myopathy that is characterized by hypotonia and proximal muscle weakness. In a large Mexican kindred with an unusually severe and highly penetrant form of the disorder, DNA sequencing identified an I4898T mutation in the C-terminal transmembrane/luminal region of the RyR1 protein that constitutes the skeletal muscle ryanodine receptor. All previously reported RYR1 mutations are located either in the cytoplasmic N terminus or in a central cytoplasmic region of the 5,038-aa protein. The I4898T mutation was introduced into a rabbit RYR1 cDNA and expressed in HEK-293 cells. The response of the mutant RyR1 Ca2+ channel to the agonists halothane and caffeine in a Ca2+ photometry assay was completely abolished. Coexpression of normal and mutant RYR1 cDNAs in a 1:1 ratio, however, produced RyR1 channels with normal halothane and caffeine sensitivities, but maximal levels of Ca2+ release were reduced by 67%. [3H]Ryanodine binding indicated that the heterozygous channel is activated by Ca2+ concentrations 4-fold lower than normal. Single-cell analysis of cotransfected cells showed a significantly increased resting cytoplasmic Ca2+ level and a significantly reduced luminal Ca2+ level. These data are indicative of a leaky channel, possibly caused by a reduction in the Ca2+ concentration required for channel activation. Comparison with two other coexpressed mutant/normal channels suggests that the I4898T mutation produces one of the most abnormal RyR1 channels yet investigated, and this level of abnormality is reflected in the severe and penetrant phenotype of affected central core disease individuals.
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Affiliation(s)
- P J Lynch
- Department of Biochemistry, University College Cork, Ireland
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Abstract
A process for mutation and polymorphism detection is described here that offers significant advances over current mutation detection systems and that has the potential to significantly enhance molecular genetic analysis of human disease. This novel process is referred to as glycosylase mediated polymorphism detection (GMPD) and exploits the use of highly specific DNA glycosylase enzymes to excise substrate bases incorporated into amplified DNA. Action of the glycosylase leaves the DNA with one or more specific abasic sites which can be cleaved by enzymatic or chemical means. The GMPD process permits detection of polymorphisms and mutations using fragment size analysis or solid phase formats. GMPD is particularly suitable for genotyping of single nucleotide polymorphism (SNP) based markers and also permits efficient scanning of genes for unknown polymorphisms and mutations.
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Affiliation(s)
- P Vaughan
- National Food Biotechnology Centre, University College, Cork, Ireland.
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Kapsa RM, Quigley AF, Han TF, Jean-Francois MJ, Vaughan P, Byrne E. mtDNA replicative potential remains constant during ageing: polymerase gamma activity does not correlate with age related cytochrome oxidase activity decline in platelets. Nucleic Acids Res 1998; 26:4365-73. [PMID: 9742236 PMCID: PMC147866 DOI: 10.1093/nar/26.19.4365] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Progressive age-related oxidative phosphorylation (OxPhos) decline is well known in human tissues. Depletion of mitochondrial DNA (mtDNA) causes OxPhos defects in patients with myopathic syndromes and deficient mtDNA replication has been observed in cells cultured from patients with mitochondrial disease. Patients undergoing treatment for AIDS develop OxPhos defects via mtDNA depletion resulting from inhibition of mtDNA polymerase gamma (Polgamma) by 2'-deoxy 3'-azido thymidine. These findings by others give rise to a possible link between mtDNA replication and bioenergetic decline in disease and during ageing. We have designed an in vitro assay for Polgamma function in small tissue samples to explore this possible link. Platelet homogenate Polgamma showed an activity with a K m of 150 microM (dTTP), a V max of 11.8 pmol/min/mg, inhibited (41% inhibition; 50 microM) by ethidium bromide. Determination of several storage characteristics showed that platelets were a convenient source of Polgamma for assay. Polgamma activity in 45 subjects did not coincide with significant age-related decline (P<0.002; P) observed in cytochrome oxidase (CytOx) activity or with citrate synthase activity. Of the activities studied, the only significant age-wise variation was a 24% CytOx deficiency in elderly (>50; n = 19) compared to young (<51; n = 24) individuals (P<0.01; t). These results suggest a maintenance of total cellular mtDNA Polgamma processive levels during ageing, largely independent of total cellular bioenergetic status or mitochondrial number/density. The processive component of Polgamma is therefore unlikely to make a major contribution to age-related bioenergetic activity decline. This does not, however, preclude the possibility that transient periods of inhibition at crucial points of the cell cycle or development may augment existing intracellular deficiencies. The assay described here greatly facilitates study of Polgamma activity in patients with conditions involving mtDNA depletion or rearrangement.
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Affiliation(s)
- R M Kapsa
- Melbourne Neuromuscular Research Centre and Department of Clinical CSIRO Division of Molecular Science, Parkville Laboratory, Parkville, Victoria 3052, Australia.
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Yin C, Jiranek WA, Vaughan P, Cardea JA. Differential messenger ribonucleic acid expression in aggressive versus linear periprosthetic osteolysis. Clin Orthop Relat Res 1998:95-104. [PMID: 9678037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Osteolysis is a radiographic term used to describe bone resorption adjacent to prosthetic implants. This process involves a spectrum of radiographic presentations, from small generalized linear patterns (linear osteolysis) to larger erosive patterns (aggressive osteolysis). The tissue from aggressive osteolytic lesions from five patients were compared with a series of linear osteolytic lesions from five additional patients. Total ribonucleic acid was extracted from these tissue samples, followed by reverse transcription and amplification by the polymerase chain reaction using a series of primers intended to amplify all ribonucleic acid species. The polymerase chain reaction products were separated by gel electrophoresis and compared by side by side analysis (differential display techniques). Transcription initiation factor IIB and cytokine receptor CRFB4 messenger ribonucleic acid were expressed in four of five patients with aggressive osteolytic lesions, as compared with none of five patients with linear osteolytic lesions. Conversely, nonmuscle myosin heavy chain messenger ribonucleic acid was expressed in five of five patients with linear osteolysis, and in none of the five patients with aggressive osteolysis. Thus, there is a difference in cell behavior between linear and aggressive osteolytic lesions that likely accounts for differences in radiographic appearance. This disparity is likely attributable to differences in local conditions (greater amounts of debris, increasing instability of the implant, or increased fluid pressures within the osteolytic lesions), and differences in host response.
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Affiliation(s)
- C Yin
- Department of Orthopaedic Surgery, Virginia Commonwealth University, Richmond 23298-0694, USA
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McGrath A, Vaughan P, McCarthy TV. A DNA glycosylase-based fingerprint for accurate identification of amplified DNA products and its application in the accurate diagnosis of infectious organisms. Anal Biochem 1998; 259:288-92. [PMID: 9618213 DOI: 10.1006/abio.1998.2673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- A McGrath
- Department of Biochemistry, University College Cork, Cork, Ireland
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Manning BM, Quane KA, Ording H, Urwyler A, Tegazzin V, Lehane M, O'Halloran J, Hartung E, Giblin LM, Lynch PJ, Vaughan P, Censier K, Bendixen D, Comi G, Heytens L, Monsieurs K, Fagerlund T, Wolz W, Heffron JJ, Muller CR, McCarthy TV. Identification of novel mutations in the ryanodine-receptor gene (RYR1) in malignant hyperthermia: genotype-phenotype correlation. Am J Hum Genet 1998; 62:599-609. [PMID: 9497245 PMCID: PMC1376943 DOI: 10.1086/301748] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that is triggered in genetically predisposed individuals by common anesthetics and muscle relaxants. The ryanodine receptor (RYR1) is mutated in a number of MH pedigrees, some members of which also have central core disease (CCD), an inherited myopathy closely associated with MH. Mutation screening of 6 kb of the RYR1 gene has identified four adjacent novel mutations, C6487T, G6488A, G6502A, and C6617T, which result in the amino acid alterations Arg2163Cys, Arg2163His, Val2168Met, and Thr2206Met, respectively. Collectively, these mutations account for 11% of MH cases and identify the gene segment 6400-6700 as a mutation hot spot. Correlation analysis of the in vitro contracture-test data available for pedigrees bearing these and other RYR1 mutations showed an exceptionally good correlation between caffeine threshold and tension values, whereas no correlation was observed between halothane threshold and tension values. This finding has important ramifications for assignment of the MH-susceptible phenotype, in genotyping studies, and indicates that assessment of recombinant individuals on the basis of caffeine response is justified, whereas assessment on the basis of halothane response may be problematic. Interestingly, the data suggest a link between the caffeine threshold and tension values and the MH/CCD phenotype.
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Affiliation(s)
- B M Manning
- Department of Biochemistry, University College Cork, Cork, Ireland
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Abstract
A novel process is presented for the detection of known mutations and polymorphisms in DNA. This process, termed glycosylase mediated polymorphism detection (GMPD) involves amplification of the target DNA using three normal dNTPs and a fourth modified dNTP, whose base is a substrate for a specific DNA-glycosylase once incorporated into the DNA. The work described here utilises uracil DNA-glycosylase as the specific glycosylase and dUTP as the modified dNTP. Primers are designed so that during extension, the position of the first uracil incorporated into the extended primers differs depending on whether a mutation is present or absent. Subsequent glycosylase excision of the uracil residues followed by cleavage of the apyrimidinic sites allows detection of the mutation in the amplified fragment as a fragment length polymorphism. Variation in the sizes of the fragment length polymorphisms generated, can be readily achieved through the use of inosine bases in place of adenine bases in the upper and/or lower primers. The GMPD process is also adaptable to solid phase analysis. The use of the process for detection of mutations in the RYR1 and CFTR genes is demonstrated. Overall, the simplicity, specificity, versatility and flexibility of the GMPD process make it an attractive candidate for both small and large scale application in mutation detection and genome analysis.
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Affiliation(s)
- P Vaughan
- Department of Biochemistry and National Food Biotechnology Centre, University College, Cork, Ireland
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Vaughan P. You can go home again. CMAJ 1997; 157:1728-9. [PMID: 9418674 PMCID: PMC1228661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Vaughan P. In harm's way. CMAJ 1997; 156:855-6. [PMID: 9084394 PMCID: PMC1227052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- P Vaughan
- Johns Hopkins School of Hygiene and Public Health, Baltimore
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Vaughan P. Finding the heart of medicine at the end of the road in Guatemala. CMAJ 1996; 155:1733-4. [PMID: 8976339 PMCID: PMC1335507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Canadian physician Peter Vaughan recently participated in a medical mission in Guatemala. He recalled that a visit to the war-torn country 20 years earlier had inspired him to go into medicine; his return visit this past March to share his medical skills reconfirmed his decision.
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Vaughan P. Mental health. Screen test. Health Serv J 1996; 106:31. [PMID: 10162640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- P Vaughan
- Loddon Community Trust, North Hampshire, UK
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Vaughan P. Creutzfeldt-Jakob disease latest unknown in struggle to restore faith in blood supply. CMAJ 1996; 155:565-8. [PMID: 8804263 PMCID: PMC1335038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
There was considerable medical interest in a recent Toronto conference on prion disease--and in Creutzfeldt-Jakob disease (CJD) in particular--because of the recent tainted-beef controversy in Britain. Although there is no proven link between a newly recognized variant form of CJD and "mad cow disease," and no evidence that CJD can be spread through the blood supply, the theoretical risk has scientists scrambling to understand how the disease is spread and policymakers struggling with the thorny issue of whether to notify persons who have received blood or blood products that may place them at risk. Until the mysteries of prion diseases and their transmission are unravelled, Dr. Peter Vaughan reports, physicians and their patients will have to live with uncertainty.
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Affiliation(s)
- P Vaughan
- Johns Hopkins School of Hygiene and Public Health, USA
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Vaughan P. Canada considers capitation fee for GPs. BMJ 1995; 311:707. [PMID: 7549680 DOI: 10.1136/bmj.311.7007.707a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Abstract
BACKGROUND Construction is one of the most dangerous industries in the world. However, there has been little literature on occupational epidemiology in this field. A study of the mortality experience over a 13-year period among construction workers in the UK was carried out. METHOD This was based on 15,007 death certificates of members of the Building and Civil Engineering Holiday and Benefit Scheme, who had died during 1975 to 1987 aged 20-64 years. Proportional mortality ratio (PMR) and mortality odds ratio techniques were used. RESULTS Significantly elevated PMR were found for deaths from all cancers, including cancer of the lung and stomach, and for accidental deaths. Associations were demonstrated between several job categories and an increased risk of cancer mortality. Occupational exposures to hazardous substances may have contributed to the elevated cancer mortality, although the study findings should be interpreted with caution. Inadequate supervision of safety procedures, together with a high proportion of young and inexperienced workers, may be associated with the high number of accidental deaths. CONCLUSIONS The results support the hypothesis that working in the construction industry is associated with a high risk for accidental death and probably also for malignant diseases including lung, mesothelium and stomach cancers. Further epidemiological studies among construction workers are needed to support policies aimed at improving occupational health, including the prevention of accidents.
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Affiliation(s)
- W Dong
- Department of Epidemiology and Public Health, University College, London, UK
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Vaughan P. Canadian medical residents strike over fees. West J Med 1995. [DOI: 10.1136/bmj.311.6999.214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Vaughan P. Canada's health care system faces criticism. BMJ 1995; 310:1285. [PMID: 7773035 DOI: 10.1136/bmj.310.6990.1285a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Vaughan P, Lindahl T, Sedgwick B. Induction of the adaptive response of Escherichia coli to alkylation damage by the environmental mutagen, methyl chloride. Mutat Res 1993; 293:249-57. [PMID: 7679475 DOI: 10.1016/0921-8777(93)90076-s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Methyl chloride (MeCl) is an abundant environmental mutagen and carcinogen and may be one of several environmental alkylating agents against which the protection of an adaptive response is required in microorganisms. Both MeCl and methyl iodide (MeI), at micromolar concentrations, induced the adaptive response to alkylation damage in Escherichia coli. This response is regulated by the Ada protein which is converted into a transcriptional activator by self-methylation on repair of methylphosphotriesters in methylated DNA. However, using high amounts of Ada protein, activation of Ada occurred in vitro following direct protein methylation by both MeI (in agreement with previously published data) and MeCl. Activation was enhanced when methyl halide treatments were performed in the presence of DNA. An unadapted E. coli cell contains only 2 to 4 molecules of Ada protein, and presents an extremely small target of 2 to 4 specific cysteine residues per cell for activation of Ada by direct protein methylation in vivo. Thus, it is proposed that induction of the adaptive response in vivo initially occurs via efficient repair by the Ada protein of a low number of methylphosphotriesters in DNA. When the cellular Ada protein level has substantially increased, a greater probability of direct methylation and activation of Ada at cysteine-69 by MeCl may sustain and further increase induction of the adaptive response.
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Affiliation(s)
- P Vaughan
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Potters Bar, Herts, UK
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Abstract
At pH 5 the steady-state chloride chord conductance in frog skeletal muscle rises to an asymptotic maximum at very negative voltages and approaches an asymptotic minimum at positive voltages. When a two-pulse test paradigm is used, the conductance computed from steady-state currents during the first (conditioning) voltage step are not duplicated by the conductance at the onset of a second (test) step. If the test step is to a more negative voltage than the conditioning step the steady-state conductance is overestimated; if it is to a less negative voltage the conductance is underestimated. In some fibres the initial currents accompanying steps from the resting potential are inwardly rectified. From this it was inferred that chloride channel conductance is voltage dependent: in those fibres in which no such initial inward rectification was observed it was inferred that at rest the voltage-dependent chloride channels are all closed. Time-dependent ("gated") changes of conductance could be reasonably described by a first-order process, but the relaxations were not simple exponentials. Simulation of the experimental set-up predicted the type of deviation from exponentiality seen experimentally, although the observed deviations were often more pronounced than those predicted.
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Affiliation(s)
- P Vaughan
- Department of Physiology, University of British Columbia, Vancouver, Canada
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Abstract
Many bacterial species have adaptive responses which protect against the toxicity and mutagenicity of methylating agents. Induced 3-methyladenine-DNA glycosylase and O6-methylguanine-DNA methyltransferase activities increase the cellular capacity of E. coli, B. subtilis, and M. luteus to repair toxic and mutagenic methylated base derivatives in DNA. The DNA methyltransferase or Ada protein of E. coli regulates the response and is converted into a strong transcriptional activator by self-methylation on repair of a methylphosphotriester in DNA. The multiple functions of the E. coli Ada protein (39 kDa) are split between two proteins, AdaA (24 kDa) and AdaB (20 kDa), in B. subtilis. Proteins (39 kDa) recognised by anti-Ada antibodies are efficiently induced in several enterobacterial species and correlate with increased DNA methyltransferase activities. In contrast, an "Ada-related" protein is only weakly induced in Salmonella typhimurium and no increase in DNA repair activity is detectable. The existence of adaptive responses in diverged bacterial species suggests the frequent occurrence of methylating agents in the environment. Several direct-acting methylating agents which are known to arise in the environment have been shown to induce the response. These include abundantly occurring methyl chloride, the antibiotic streptozotocin, the precursors of the known labile inducers N-methyl-N'-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine and as shown in this paper, methyl radicals which may arise by the irradiation or oxidation of methyl compounds.
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Affiliation(s)
- B Sedgwick
- Imperial Cancer Research Fund, Potters Bar, Herts., Great Britain
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Vaughan P. Substitute anions and the chloride conductance of frog muscle: effects of chlorate and bromate on steady-state values and kinetics. Pflugers Arch 1991; 419:152-9. [PMID: 1961685 DOI: 10.1007/bf00373001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Voltage-clamp experiments have been used to study the effects of external nitrate, chlorate and bromate on the chloride conductance of sarcolemma of Xenopus laevis. Nitrate reduces inward current (chloride efflux), but less potently than does thiocyanate [Vaughan (1987) Pflügers Arch 410:153-158] and does not affect conductance kinetics. As its concentration is increased the blocking effect of nitrate saturates; at a nitrate mole fraction of 0.6 the anion conductance is reduced to about 50% and further increases in nitrate concentration are without significant effect. Nitrate's influences are not voltage-dependent. Chlorate is a much less potent blocker than is nitrate, and its effects are voltage-dependent. With small hyperpolarizations, currents are sometimes seen to be larger than the control, but the degree of block (or the conversion of augmentation to reduction) increases with the size of the voltage step. Anomalous mole-fraction effects are observed in the range 0.4-0.6 mol/mol, in that in some cells the reduction of conductance is noticeably greater in the lower than in the higher concentration of the replacement ion. In the presence of chlorate, relaxation rates are significantly increased, and this influence is not anomalously dependent on the mole fraction. Similar effects are observed in bromate. The effect on kinetics is not pH-dependent. The main series of experiments was conducted at pH 5, but the same influence on kinetics was observed at pH 9. Using point voltage-clamp experiments, chlorate and thiocyanate were both seen to lower the contraction threshold voltage, but thiocyanate has no influence on conductance kinetics.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P Vaughan
- Department of Physiology, University of British Columbia, Vancouver, Canada
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Abstract
An efficient adaptive response to alkylation damage was observed in several enterobacterial species, including Klebsiella aerogenes, Shigella sonnei, Shigella boydii, Escherichia alkalescens, Escherichia hermanii, and Escherichia fergusonii. Increased O6-methylguanine-DNA and methylphosphotriester-DNA methyltransferase activities correlated with the induction of a 39-kDa protein recognized by monoclonal antibodies raised against the Escherichia coli Ada protein. Induced methyltransferase activities were similarly observed in Aerobacter aerogenes and Citrobacter intermedius, although no antigenically cross-reacting material was present. Weak induction of a 39-kDa protein immunologically related to the E. coli Ada protein occurred in Salmonella typhimurium. This protein encoded by the cloned S. typhimurium ada gene was shown to be an active methyltransferase which repaired O6-methylguanine and methylphosphotriesters in DNA as efficiently as did the E. coli Ada protein. However, the mehtyltransferase activity of the weakly induced 39-kDa protein in S. typhimurium was not detected, apparently because it was self-methylated and thus inactivated during the adaptive N-methyl-N-nitro-N-nitrosoguanidine pretreatment. In contrast, the E. coli ada gene on a low-copy-number plasmid was efficiently induced in S. typhimurium, and high methyltransferase activities were observed. We concluded that the inefficient induction of the adaptive response in S. typhimurium results from weak transcriptional activation of its ada gene by the self-methylated protein.
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Affiliation(s)
- P Vaughan
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom
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Vaughan P. Rules of engagement: key factors in the successful management of interagency projects. Health Serv Manage 1991; 87:126-8. [PMID: 10111609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
In recent years the implementation of community care policies in relation to the mentally ill has led to increasing collaboration between the caring agencies. Unfortunately early experience has shown that joint projects employing multidisciplinary mental health teams are difficult and time consuming to manage. Phillip Vaughan comments on some of the difficulties encountered by such teams and offers suggestions for their remedy.
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Vaughan P, Sedgwick B, Hall J, Gannon J, Lindahl T. Environmental mutagens that induce the adaptive response to alkylating agents in Escherichia coli. Carcinogenesis 1991; 12:263-8. [PMID: 1995192 DOI: 10.1093/carcin/12.2.263] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Many microorganisms exhibit an adaptive response to mutagenic alkylation damage. In Escherichia coli the response is regulated by the inducible Ada protein. A sensitive immunoassay employing two anti-Ada monoclonal antibodies has been developed here to monitor low levels of induction of the Ada protein. This protein was detected in non-induced E. coli which contained an average of two molecules of Ada per cell. The occurrence of the adaptive response in bacteria signals the existence of an ecological niche in which cells are exposed to direct-acting methylating compounds, but the structure and identity of these agents are unknown. Using the immunoassay to search for possible candidates, a number of methylating agents and precursors of such agents have been investigated. Carbamyl phosphate and methylamine yield N-methylurea, which reacts subsequently with nitrite to generate the strong inducer N-methyl-N-nitrosourea. The antibiotic streptozotocin also is a potent inducer of the adaptive response. Moreover, the abundant environmental mutagen methyl chloride acts as an inducer.
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Affiliation(s)
- P Vaughan
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK
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Vaughan P, Brooks C. Adult respiratory distress syndrome. A complication of shock. Crit Care Nurs Clin North Am 1990; 2:235-53. [PMID: 2192728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
ARDS is a complex type of respiratory failure that usually is a complication of a catastrophic critical illness, such as shock. Mortality is high, especially in patients with septic shock and multisystem failure. Mortality often is related to complications of refractory hypoxemia. Identifying patients at risk for developing ARDS and early recognition of ARDS are important so that treatment can be initiated to prevent the potentially lethal consequences of refractory hypoxemia. The nurse has an important role in collaborating with the physician and respiratory therapist to support the patient's oxygenation, ventilation, and tissue oxygen delivery system. The nurse is responsible for performing highly sophisticated assessment of clinical and hemodynamic parameters to evaluate the effectiveness of therapy. A key role of the nurse is anticipating, recognizing, and reporting to the physician complications of hypoxemia and complications of therapy that can lead to sepsis, airway trauma, or failure of other organ systems.
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Abstract
Voltage clamp experiments in muscle show that the steady state chloride conductance at pH 9 remains rather independent of [Cl-]o, for [Cl-]o in the range 165-265 mM. The steady state conductance-voltage relation has a maximum near Vrest -20 mV. The initial-conductance-voltage relation obtained when the voltage is stepped away from a constant conditioning value (e.g. the resting potential) approaches an asymptotic maximum for hyperpolarizing steps and a minimum for depolarizing steps. The conductance declines with time if the test voltage is more negative than the resting potential, but remains constant if it is more positive. When the conditioning voltage is varied and the test kept constant the initial conductance at the step is also seen to be sigmoidal, if the test step is hyperpolarizing: for large negative conditioning steps the conductance at the test potential approaches the same asymptotic value as does the steady state relation, independent of the test voltage. At positive conditioning voltages it approaches a maximum asymptote which is dependent on the test voltage. When the test step is positive-going the initial conductance at the step is weakly dependent on the conditioning voltage and for large negative conditioning potentials is larger than predicted from the steady state relation. In summary, during hyperpolarizing voltage steps the chloride conductance seems to decline due to a "gating" phenomenon, but openstate conductance seems to be voltage-dependent, and at membrane potentials more positive than the resting it rapidly (within the settling time of the clamp) assumes a value almost independent of any preceding (conditioning) voltage.
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Affiliation(s)
- P Vaughan
- Department of Physiology, University of British Columbia, Vancouver, Canada
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Vaughan P, O’Dea J, Cunningham AJ, Crowley K, Boyle T, Scunitlger T, Browne L, Gallagher J, McDevitt S, Cunningham AJ, Raftery S, Warde D, Patterson K, Warde D, O’Flaherty D. Royal Academy of Medicine in Ireland Section of Anaesthesia. Ir J Med Sci 1989. [DOI: 10.1007/bf02943618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Vaughan P. Home study program. Bedside assessment of the myocardial infarction patient. Crit Care Nurse 1984; 4:59-77. [PMID: 6561996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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Vaughan P. Home study program. Bedside assessment of the myocardial infarction patient. Crit Care Nurse 1984. [DOI: 10.4037/ccn1984.4.2.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Vaughan P. Arrhythmia quiz. Crit Care Nurse 1983. [DOI: 10.4037/ccn1983.3.6.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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