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Lupu M, Maillard P, Mispelter J, Poyer F, Thomas CD. A glycoporphyrin story: from chemistry to PDT treatment of cancer mouse models. Photochem Photobiol Sci 2018; 17:1599-1611. [DOI: 10.1039/c8pp00123e] [Citation(s) in RCA: 10] [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: 12/11/2022]
Abstract
Glycoporphyrin: from bench to preclinical studies on PDX xenografted on mice.
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Affiliation(s)
- M. Lupu
- Institut Curie
- Research Center
- PSL Research University
- CNRS
- INSERM
| | - Ph. Maillard
- Institut Curie
- Research Center
- PSL Research University
- CNRS
- INSERM
| | - J. Mispelter
- Institut Curie
- Research Center
- PSL Research University
- CNRS
- INSERM
| | - F. Poyer
- Institut Curie
- Research Center
- PSL Research University
- CNRS
- INSERM
| | - C. D. Thomas
- Institut Curie
- Research Center
- PSL Research University
- CNRS
- INSERM
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2
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Singer MC, Ng D, Thomas CD. HERITABILITY OF OVIPOSITION PREFERENCE AND ITS RELATIONSHIP TO OFFSPRING PERFORMANCE WITHIN A SINGLE INSECT POPULATION. Evolution 2017; 42:977-985. [DOI: 10.1111/j.1558-5646.1988.tb02516.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/1987] [Accepted: 04/27/1988] [Indexed: 11/27/2022]
Affiliation(s)
- M. C. Singer
- Department of Zoology University of Texas Austin TX 78712
| | - D. Ng
- Department of Zoology University of Texas Austin TX 78712
| | - C. D. Thomas
- Department of Zoology University of Texas Austin TX 78712
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3
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Thomas CD, Ng D, Singer MC, Mallet JLB, Parmesan C, Billington HL. INCORPORATION OF A EUROPEAN WEED INTO THE DIET OF A NORTH AMERICAN HERBIVORE. Evolution 2017; 41:892-901. [DOI: 10.1111/j.1558-5646.1987.tb05862.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/1986] [Accepted: 01/09/1987] [Indexed: 12/01/2022]
Affiliation(s)
- C. D. Thomas
- Department of Zoology University of Texas Austin TX 78712
| | - D. Ng
- Department of Zoology University of Texas Austin TX 78712
| | - M. C. Singer
- Department of Zoology University of Texas Austin TX 78712
| | | | - C. Parmesan
- Department of Zoology University of Texas Austin TX 78712
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4
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Gallud A, Warther D, Maynadier M, Sefta M, Poyer F, Thomas CD, Rouxel C, Mongin O, Blanchard-Desce M, Morère A, Raehm L, Maillard P, Durand JO, Garcia M, Gary-Bobo M. Identification of MRC2 and CD209 receptors as targets for photodynamic therapy of retinoblastoma using mesoporous silica nanoparticles. RSC Adv 2015. [DOI: 10.1039/c5ra14640b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An overexpression of MRC2 and CD209 mannose receptors was revealed in retinoblastoma and antibodies against these receptors were grafted to multifunctional nanoparticles for targeting of imaging and photodynamic therapy.
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5
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Affiliation(s)
| | - B. Huntley
- School of Biological and Biomedical Sciences; Durham University; South Road; Durham; DH1 3LE; UK
| | - W. E. Kunin
- Institute of Integrative and Comparative Biology; Faculty of Biological Sciences; University of Leeds; Leeds; UK; LS2 9JT
| | - C. D. Thomas
- Department of Biology; University of York; Wentworth Way; Heslington; York; YO10 5DD; UK
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6
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Maillard P, Lupu M, Thomas CD, Mispelter J. [Towards a new treatment of retinoblastoma?]. Ann Pharm Fr 2010; 68:195-202. [PMID: 20569775 DOI: 10.1016/j.pharma.2010.03.001] [Citation(s) in RCA: 4] [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] [Received: 08/18/2009] [Revised: 02/24/2010] [Accepted: 03/04/2010] [Indexed: 01/10/2023]
Abstract
Photodynamic therapy (PDT) is a recent approach for the treatment of small cancerous tumours, on-surface or accessible by endoscopy in which a dye (usually a tetrapyrrolic macrocycle) absorbs light and generates cytotoxic reactive oxygen species leading to cellular damage. Retinoblastoma (Rb) is a rare intraocular tumour of childhood. All the multifocal forms are hereditary and constitute a syndrome of genetic predisposition in the cancer. The current treatments with etoposide or carboplatine expose the patient to the late risk of second cancer. The use of PDT as cancer therapy is particularly attractive due to the use of few mutagenic and non-toxic photosensitizers (PS) prior light excitation and to the localized tumour illumination. The photoefficiency towards Rb of a glycoconjugated porphyrin is discussed and compared with the results obtained with a second-generation photosensitizer, the Foscan. Some in vivo results on an animal model of Rb are presented by a point of view of photoefficiency, biodistribution, pharmacokinetic and longitudinal follow-up of the PDT effect using a new non-invasive method of magnetic resonance imaging of real-time. Photodynamic treatments in association with non-invasive sodium imaging open ways for new treatment tailoring or treatment individualization of retinoblastoma in clinic.
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Affiliation(s)
- P Maillard
- UMR 176 CNRS, institut Curie, bâtiments 110-112, centre universitaire, université Paris-Sud, 91405 Orsay, France.
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7
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Machón C, Lynch GP, Thomson NH, Scott DJ, Thomas CD, Soultanas P. RepD-mediated recruitment of PcrA helicase at the Staphylococcus aureus pC221 plasmid replication origin, oriD. Nucleic Acids Res 2009; 38:1874-88. [PMID: 20044350 PMCID: PMC2847222 DOI: 10.1093/nar/gkp1153] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Plasmid encoded replication initiation (Rep) proteins recruit host helicases to plasmid replication origins. Previously, we showed that RepD recruits directionally the PcrA helicase to the pC221 oriD, remains associated with it, and increases its processivity during plasmid unwinding. Here we show that RepD forms a complex extending upstream and downstream of the core oriD. Binding of RepD causes remodelling of a region upstream from the core oriD forming a ‘landing pad’ for the PcrA. PcrA is recruited by this extended RepD–DNA complex via an interaction with RepD at this upstream site. PcrA appears to have weak affinity for this region even in the absence of RepD. Upon binding of ADPNP (non-hydrolysable analogue of ATP), by PcrA, a conformational rearrangement of the RepD–PcrA–ATP initiation complex confines it strictly within the boundaries of the core oriD. We conclude that RepD-mediated recruitment of PcrA at oriD is a three step process. First, an extended RepD–oriD complex includes a region upstream from the core oriD; second, the PcrA is recruited to this upstream region and thirdly upon ATP-binding PcrA relocates within the core oriD.
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Affiliation(s)
- C. Machón
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
| | - G. P. Lynch
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
| | - N. H. Thomson
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
| | - D. J. Scott
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
| | - C. D. Thomas
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
| | - P. Soultanas
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham University Park, Nottingham NG7 2RD, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT and National Centre for Molecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, Leics LE12 5RD, UK
- *To whom correspondence should be addressed. Tel: +44 0 1159513525; Fax: +44 0 1158468002;
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Robinson RA, Crick HQP, Learmonth JA, Maclean IMD, Thomas CD, Bairlein F, Forchhammer MC, Francis CM, Gill JA, Godley BJ, Harwood J, Hays GC, Huntley B, Hutson AM, Pierce GJ, Rehfisch MM, Sims DW, Santos BM, Sparks TH, Stroud DA, Visser ME. Travelling through a warming world: climate change and migratory species. ENDANGER SPECIES RES 2009. [DOI: 10.3354/esr00095] [Citation(s) in RCA: 234] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Hoegh-Guldberg O, Hughes L, McIntyre S, Lindenmayer DB, Parmesan C, Possingham HP, Thomas CD. ECOLOGY: Assisted Colonization and Rapid Climate Change. Science 2008; 321:345-6. [PMID: 18635780 DOI: 10.1126/science.1157897] [Citation(s) in RCA: 349] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- O Hoegh-Guldberg
- Centre for Marine Studies, Australian Research Council Centre for Excellence in Reef Studies and the Coral Reef Targeted Research Project, University of Queensland, St Lucia, Queensland (QLD) 4072, Australia.
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10
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Kremen C, Cameron A, Moilanen A, Phillips SJ, Thomas CD, Beentje H, Dransfield J, Fisher BL, Glaw F, Good TC, Harper GJ, Hijmans RJ, Lees DC, Louis E, Nussbaum RA, Raxworthy CJ, Razafimpahanana A, Schatz GE, Vences M, Vieites DR, Wright PC, Zjhra ML. Aligning Conservation Priorities Across Taxa in Madagascar with High-Resolution Planning Tools. Science 2008; 320:222-6. [PMID: 18403708 DOI: 10.1126/science.1155193] [Citation(s) in RCA: 379] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- C Kremen
- Department of Environmental Sciences, Policy and Management, 137 Mulford Hall, University of California, Berkeley, CA 94720-3114, USA.
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11
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Biesmeijer JC, Roberts SPM, Reemer M, Ohlemüller R, Edwards M, Peeters T, Schaffers AP, Potts SG, Kleukers R, Thomas CD, Settele J, Kunin WE. Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands. Science 2006; 313:351-4. [PMID: 16857940 DOI: 10.1126/science.1127863] [Citation(s) in RCA: 1143] [Impact Index Per Article: 63.5] [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: 11/02/2022]
Abstract
Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.
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Affiliation(s)
- J C Biesmeijer
- Institute of Integrative and Comparative Biology and Earth and Biosphere Institute, University of Leeds, Leeds, LS2 9JT, UK.
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12
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Biesmeijer JC, Roberts SPM, Reemer M, Ohlemüller R, Edwards M, Peeters T, Schaffers AP, Potts SG, Kleukers R, Thomas CD, Settele J, Kunin WE. Parallel declines in pollinators and insect-pollinated plants in Britain and the Netherlands. Science 2006. [PMID: 16857940 DOI: 10.1126/science.112786] [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: 05/05/2023]
Abstract
Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.
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Affiliation(s)
- J C Biesmeijer
- Institute of Integrative and Comparative Biology and Earth and Biosphere Institute, University of Leeds, Leeds, LS2 9JT, UK.
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13
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Castelletto V, Hamley IW, Kerstens SLH, Deacon S, Thomas CD, Lübbert A, Klok HA. Spontaneous condensation in DNA-polystyrene- b-poly(l-lysine) polyelectrolyte block copolymer mixtures. Eur Phys J E Soft Matter 2006; 20:1-6. [PMID: 16733633 DOI: 10.1140/epje/i2005-10074-x] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Accepted: 02/10/2006] [Indexed: 05/09/2023]
Abstract
We investigated the condensation of calf thymus DNA by amphiphilic polystyrene(m)-b-poly(l-lysine)(n) block copolymers ( PS(m)-b- PLys(n), m, n = degree of polymerization), using small-angle X-ray scattering, polarized optical microscopy and laser scanning confocal microscopy. Microscopy studies showed that the DNA condenses in the form of fibrillar precipitates, with an irregular structure, due to electrostatic interactions between PLys and DNA. This is not modified by the presence of hydrophobic PS block. Scattering experiments show that the structure of the polyplexes corresponds to a local order of DNA rods which becomes more compact upon increasing n. It can be concluded that for DNA/ PS(m)-b- PLys(n) polyplexes, the balance between the PLys block length and the excess charge in the system plays an essential role in the formation of a liquid crystalline phase.
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Affiliation(s)
- V Castelletto
- School of Chemistry, The University of Reading, P.O. Box 224, RG6 6AD, Whiteknights, Reading, UK.
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Paton RW, Hinduja K, Thomas CD. The significance of at-risk factors in ultrasound surveillance of developmental dysplasia of the hip. A ten-year prospective study. ACTA ACUST UNITED AC 2005; 87:1264-6. [PMID: 16129755 DOI: 10.1302/0301-620x.87b9.16565] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [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: 12/15/2022]
Abstract
Of the 34,723 infants born between 1 June 1992 and 31 May 2002, the hips of 2578 with clinical instability or at-risk factors for developmental dysplasia of the hip were imaged by ultrasound. Instability of the hip was present in 77 patients, of whom only 24 (31.2%) had an associated risk factor. From the 'at-risk' groups, the overall risk of type-III dysplasia, instability and irreducibility was 1:15 when family history, 1:27 when breech delivery and 1:33 when foot deformity were considered as risk factors. Of those hips which were ultrasonographically stable, 88 had type-III dysplasia. A national programme of selective ultrasound screening of at-risk factors for the diagnosis of hip dislocation or instability alone cannot be recommended because of its low predictive value (1:88). However, the incidence of type-III dysplasia and hip dislocation or dislocatability in the groups with clinical instability, family history, breech position and possibly postural foot deformity as risk factors could justify a programme of selective ultrasound imaging.
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Affiliation(s)
- R W Paton
- Orthopaedic Department, Blackburn Royal Infirmary, Bolton Road, Blackburn BB2 3LR, Lancashire, England, UK.
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Thomas CD, Chenu E, Walczak C, Plessis MJ, Perin F, Volk A. Relationship between tumour growth rate and carbogen-based functional MRI for a chemically induced HCC in mice. MAGMA 2004; 17:271-80. [PMID: 15614512 DOI: 10.1007/s10334-004-0087-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 10/29/2004] [Accepted: 11/09/2004] [Indexed: 11/28/2022]
Abstract
We previously performed MRI studies of HCC (hepatocellular carcinomas) in mice showing the feasibility of measuring a carbogen effect. In the present study carbogen response of the whole tumour was compared with growth characteristics during longitudinal follow-up. HCC were chemically induced. The imaging protocol at 4.7 T comprised a fast spin-echo sequence for high-resolution screening and measurement of growth curves, and a fast gradient echo sequence allowing an entire T2*w image acquisition per respiratory cycle to perform fMRI under carbogen breathing. A new parameter, T+, the fraction of tumour voxels with increased intensity under carbogen was measured on manually defined ROIs. Twenty-two HCC were followed for 3-10 weeks. Tumours were divided into two groups, "regularly" and "irregularly" growing tumours. A linear correlation between T+ and tumour growth rate was observed only for "regularly" growing HCC. These results suggest a link between tumour growth rates and tumour fractions exhibiting signal increase upon carbogen breathing. They are compatible with observations by others that rapidly growing tumours are more hypoxic than slowly growing ones. Combined measurement of T+ and tumour growth may become a useful noninvasive follow-up approach for assessment and/or management of therapies involving vasculature-targeting and anti-proliferative drugs.
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Affiliation(s)
- C D Thomas
- INSERM--Curie Institute--Research, Centre Universitaire, Bâtiment 112, 91405, Orsay cedex, France.
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Vrtovec B, Thomas CD, Radovancevic R, Frazier OH, Radovancevic B. Comparison of intravenous ganciclovir and cytomegalovirus hyperimmune globulin pre-emptive treatment in cytomegalovirus-positive heart transplant recipients. J Heart Lung Transplant 2004; 23:461-5. [PMID: 15063406 DOI: 10.1016/s1053-2498(03)00200-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2002] [Revised: 04/04/2003] [Accepted: 04/17/2003] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND We compared the use of intravenous ganciclovir and cytomegalovirus hyperimmune globulin (CMVIG) as a pre-emptive treatment for cytomegalovirus (CMV)-positive heart transplant recipients. METHODS Of 59 CMV-seropositive adult heart transplant recipients enrolled in Group 1, 37 tested positive for pp65 antigen within 12 weeks post-transplantation. These patients were randomized to receive either intravenous ganciclovir (n = 23) or CMVIG (n = 14). Group 2 included 133 CMV-seropositive heart transplant recipients who were not tested for CMV antigenemia and who received no anti-CMV therapy. RESULTS CMV disease developed in 0 of 59 patients from Group 1, and in 27 of 133 patients (20%) in Group 2 (p = 0.0001). The incidence of superinfections was lower in Group 1 (0.28 +/- 0.46) than in Group 2 (1.10 +/- 1.33) (p = 0.01). The 2 groups did not differ with regard to incidence of rejection (0.7 +/- 0.9 in Group 1 vs 1.0 +/- 1.2 in Group 2; p = NS), transplant coronary artery disease at 1 year (14% in Group 1 vs 16% in Group 2; p = NS) or post-transplant lymphoproliferative disease (0% in Group 1 vs 2% in Group 2; p = NS). Ganciclovir and CMVIG therapies were associated with similar rates of rejection (0.52 +/- 0.6 with ganciclovir vs 0.50 +/- 0.60 with CMVIG; p = NS), superinfection (0.30 +/- 0.48 with ganciclovir vs 0.25 +/- 0.46 with CMVIG; p = NS), and transplant coronary artery disease at 1 year (13% with ganciclovir vs 14% with CMVIG, p = NS). CONCLUSIONS The pre-emptive anti-CMV approach is superior to prophylaxis in CMV-seropositive heart transplant recipients. Both ganciclovir and CMVIG are equally effective.
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Affiliation(s)
- B Vrtovec
- Department of Cardiopulmonary Transplantation, Texas Heart Institute, Houston, Texas 77225, USA
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18
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Bailey RI, Thomas CD, Butlin RK. Premating barriers to gene exchange and their implications for the structure of a mosaic hybrid zone between Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae). J Evol Biol 2003; 17:108-19. [PMID: 15000654 DOI: 10.1046/j.1420-9101.2003.00648.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [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: 11/20/2022]
Abstract
Many hybrid zones contain a deficit of hybrid genotypes relative to expectations from tension zone models. This is often associated with separation of parental genotypes into distinct habitats (mosaicism), but sometimes parentals can be found co-occuring in the same local population (bimodality). In both cases, prezygotic isolation may play an important role in determining the genotypic composition of the zone. Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae) meet and form a complex hybrid zone in northern Spain. Analysis of stridulatory peg numbers reveals partial spatial and seasonal isolation in a 25 km2 area of the zone: C. jacobsi phenotypes predominate in June and July and are present in both valley and mountain habitats; C. brunneus phenotypes predominate in August and are restricted to valley habitats, always in sympatry with C. jacobsi. Strong assortative mating was observed in laboratory mating experiments. Spatial, seasonal and behavioural isolation combine to produce strong premating isolation in the study area. These results suggest a role for premating isolation in maintaining both the mosaic structure and bimodality of this hybrid zone.
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Affiliation(s)
- R I Bailey
- Centre for Biodiversity and Conservation, School of Biology, University of Leeds, Leeds, UK.
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Conradt L, Zollner PA, Roper TJ, Frank K, Thomas CD. Foray search: an effective systematic dispersal strategy in fragmented landscapes. Am Nat 2003; 161:905-15. [PMID: 12858275 DOI: 10.1086/375298] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2002] [Accepted: 11/14/2002] [Indexed: 11/03/2022]
Abstract
In the absence of evidence to the contrary, population models generally assume that the dispersal trajectories of animals are random, but systematic dispersal could be more efficient at detecting new habitat and may therefore constitute a more realistic assumption. Here, we investigate, by means of simulations, the properties of a potentially widespread systematic dispersal strategy termed "foray search." Foray search was more efficient in detecting suitable habitat than was random dispersal in most landscapes and was less subject to energetic constraints. However, it also resulted in considerably shorter net dispersed distances and higher mortality per net dispersed distance than did random dispersal, and it would therefore be likely to lead to lower dispersal rates toward the margins of population networks. Consequently, the use of foray search by dispersers could crucially affect the extinction-colonization balance of metapopulations and the evolution of dispersal rates. We conclude that population models need to take the dispersal trajectories of individuals into account in order to make reliable predictions.
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Affiliation(s)
- L Conradt
- Centre for Biodiversity and Conservation, School of Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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Hill JK, Thomas CD, Fox R, Telfer MG, Willis SG, Asher J, Huntley B. Responses of butterflies to twentieth century climate warming: implications for future ranges. Proc Biol Sci 2002; 269:2163-71. [PMID: 12396492 PMCID: PMC1691143 DOI: 10.1098/rspb.2002.2134] [Citation(s) in RCA: 323] [Impact Index Per Article: 14.7] [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: 11/12/2022] Open
Abstract
We analyse distribution records for 51 British butterfly species to investigate altitudinal and latitudinal responses to twentieth century climate warming. Species with northern and/or montane distributions have disappeared from low elevation sites and colonized sites at higher elevations during the twentieth century, consistent with a climate explanation. We found no evidence for a systematic shift northwards across all species, even though 11 out of 46 southerly distributed species have expanded in the northern part of their distributions. For a subset of 35 species, we model the role of climate in limiting current European distributions and predict potential future distributions for the period 2070-2099. Most northerly distributed species will have little opportunity to expand northwards and will disappear from areas in the south, resulting in reduced range sizes. Southerly distributed species will have the potential to shift northwards, resulting in similar or increased range sizes. However, 30 out of 35 study species have failed to track recent climate changes because of lack of suitable habitat, so we revised our estimates accordingly for these species and predicted 65% and 24% declines in range sizes for northern and southern species, respectively. These revised estimates are likely to be more realistic predictions of future butterfly range sizes.
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Affiliation(s)
- J K Hill
- Department of Biology, PO Box 373, University of York, York YO10 5YW, UK.
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Cowley MJR, Thomas CD, Wilson RJ, León-Cortés JL, Gutiérrez D, Bulman CR. Density-distribution relationships in British butterflies. II. An assessment of mechanisms. J Anim Ecol 2002. [DOI: 10.1046/j.1365-2656.2001.00509.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Cowley MJR, Thomas CD, Roy DB, Wilson RJ, León-Cortés JL, Gutiérrez D, Bulman CR, Quinn RM, Moss D, Gaston KJ. Density-distribution relationships in British butterflies. I. The effect of mobility and spatial scale. J Anim Ecol 2002. [DOI: 10.1046/j.1365-2656.2001.00508.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Thomas JA, Rose RJ, Clarke RT, Thomas CD, Webb NR. Intraspecific variation in habitat availability among ectothermic animals near their climatic limits and their centres of range. Funct Ecol 2002. [DOI: 10.1046/j.1365-2435.1999.00008.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Bell KL, Loveridge N, Reeve J, Thomas CD, Feik SA, Clement JG. Super-osteons (remodeling clusters) in the cortex of the femoral shaft: influence of age and gender. Anat Rec 2001; 264:378-86. [PMID: 11745093 DOI: 10.1002/ar.10014] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previous studies of cortical remodeling in the fractured femoral neck indicated that the merging of spatially clustered remodeling osteons could result in the formation of deleteriously large cavities associated with femoral neck fracture. This study aimed to identify whether remodeling osteons in the femoral shaft were also clustered and to assess the influence of age and gender. Microradiographic images of femoral mid-shaft cross-sections from 66 subjects over 21 years of age were analyzed to determine the number, size and location of all Haversian canals. Those most recently remodeled were identified using an edge-detection algorithm highlighting the most marked differential gradients in grey levels. Cluster analysis (JMP software) of these osteons identified the proportion of recently remodeled osteons that were within 0.75 mm clusters. As in the femoral neck, remodeling osteons were significantly more clustered than could occur by chance (real, 59.4%; random, 39.4%; P < 0.0001). The density of these clusters (number/mm(2)) was not significantly associated with subject age or gender but was greatest near the periosteum and decreased toward the marrow cavity (periosteal 0.043 +/- 0.004; mid-cortex 0.028 +/- 0.003; endosteal 0.017 +/- 0.002). Cortical porosity increased with age. The presence of giant canals (diameter >385 microm) was inversely related to the presence of clusters (R(2) = 0.237, P < 0.0001). This data suggest that remodeling osteons tend to be spatially colocalized in the shaft as they are in the neck of the femur and their presence is independent of age or gender. We propose that these remodeling clusters be termed super-osteons. The negative relationship between super-osteons and giant canals raises the intriguing possibility that loss of the control of remodeling depth results in the merging of osteonal systems to form deleteriously large cortical cavities with a marked reduction in bone strength.
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Affiliation(s)
- K L Bell
- Bone Research Group (MRC), Department of Medicine, University of Cambridge, Cambridge, United Kingdom
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Warren MS, Hill JK, Thomas JA, Asher J, Fox R, Huntley B, Roy DB, Telfer MG, Jeffcoate S, Harding P, Jeffcoate G, Willis SG, Greatorex-Davies JN, Moss D, Thomas CD. Rapid responses of British butterflies to opposing forces of climate and habitat change. Nature 2001; 414:65-9. [PMID: 11689943 DOI: 10.1038/35102054] [Citation(s) in RCA: 966] [Impact Index Per Article: 42.0] [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: 11/09/2022]
Abstract
Habitat degradation and climate change are thought to be altering the distributions and abundances of animals and plants throughout the world, but their combined impacts have not been assessed for any species assemblage. Here we evaluated changes in the distribution sizes and abundances of 46 species of butterflies that approach their northern climatic range margins in Britain-where changes in climate and habitat are opposing forces. These insects might be expected to have responded positively to climate warming over the past 30 years, yet three-quarters of them declined: negative responses to habitat loss have outweighed positive responses to climate warming. Half of the species that were mobile and habitat generalists increased their distribution sites over this period (consistent with a climate explanation), whereas the other generalists and 89% of the habitat specialists declined in distribution size (consistent with habitat limitation). Changes in population abundances closely matched changes in distributions. The dual forces of habitat modification and climate change are likely to cause specialists to decline, leaving biological communities with reduced numbers of species and dominated by mobile and widespread habitat generalists.
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Affiliation(s)
- M S Warren
- Butterfly Conservation, Manor Yard, East Lulworth, Wareham, Dorset BH20 5QP, UK
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Abstract
Many animals are regarded as relatively sedentary and specialized in marginal parts of their geographical distributions. They are expected to be slow at colonizing new habitats. Despite this, the cool margins of many species' distributions have expanded rapidly in association with recent climate warming. We examined four insect species that have expanded their geographical ranges in Britain over the past 20 years. Here we report that two butterfly species have increased the variety of habitat types that they can colonize, and that two bush cricket species show increased fractions of longer-winged (dispersive) individuals in recently founded populations. Both ecological and evolutionary processes are probably responsible for these changes. Increased habitat breadth and dispersal tendencies have resulted in about 3- to 15-fold increases in expansion rates, allowing these insects to cross habitat disjunctions that would have represented major or complete barriers to dispersal before the expansions started. The emergence of dispersive phenotypes will increase the speed at which species invade new environments, and probably underlies the responses of many species to both past and future climate change.
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Affiliation(s)
- C D Thomas
- Centre for Biodiversity and Conservation, School of Biology, University of Leeds, Leeds LS2 9JT, UK.
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Abstract
Twins studies provide a powerful approach to determining the relative contribution of genetics and environment to observed variation. Such studies assume trait differences in monozygous (MZ) twins are due to environmental factors and those in dizygous (DZ) twins are due to both genetic and environmental factors. This study quantitated facial profiles of twins using Fourier equations, determining their value in profile analysis and the assessment of the genetic contribution to facial shape. Standardized profile slide photographs of 79 pairs of 4-6 year-old twins (37 MZ pairs, 42 DZ pairs) were scanned and x and y coordinates were extracted from each profile using sellion and Camper's plane as references. The coordinates were subjected to Fourier analysis and the normalised vertex projection coefficients were studied. The means of the differences between coefficients for MZ co-twins did not differ significantly from that of DZ co-twins, although the DZ group showed higher mean differences in the higher harmonics. Subjective examination of superimposed reconstructions showed wider variation between DZ co-twins than MZ co-twins. Correct classification of twins by discriminant function analysis using Fourier coefficients was similar for both groups (MZ: 70.3%; DZ: 73.8%). Fourier analysis could quantitate facial profiles of young children and differentiate some details, but was unable to discriminate between genetic and environmental influences, and any possible interactions between these influences, on their overall facial profiles at this developmental stage.
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Affiliation(s)
- K Tangchaitrong
- School of Dental Science, The University of Melbourne, 711 Elizabeth Street, Melbourne, Victoria 3000, Australia
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Conradt L, Bodsworth EJ, Roper TJ, Thomas CD. Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models. Proc Biol Sci 2000; 267:1505-10. [PMID: 11007325 PMCID: PMC1690706 DOI: 10.1098/rspb.2000.1171] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [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: 11/12/2022] Open
Abstract
The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations.
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Affiliation(s)
- L Conradt
- School of Biology, University of Leeds, UK.
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Affiliation(s)
- C D Thomas
- Department of Orthopedic Surgery, Manchester Royal Infirmary, United Kingdom
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Abstract
Lotka's law of scientific productivity is a bibliometric example: the number of authors against the number of contributions made by the authors was plotted on a logarithmic scale. The points were closely scattered around a straight line having a slope of -2. The purpose of this study was to apply information technology to real-world data and to quantify the extent of the bibliometric regularity that exists in the literature of dental science. We have analyzed the productivity index of authors (PI) in a scientific journal (Journal of American Dental Association). Details of a total of 4,088 papers published between 1966 and 1995 were extracted electronically from MEDLINE. The total number of authors was 5,589, responsible for 8,569 authorships. Only 0.8% of the authors presented a PI > = 1 (large producers), and 78.1% a PI = 0 (occasional authors). The number of authors publishing N papers was 1/N2.64 of those publishing one paper. The result suggested that repeated publications in the Journal were more difficult than those predicted by Lotka (1/N2).
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Affiliation(s)
- M Kawamura
- Department of Preventive Dentistry, Faculty of Dentistry, Hiroshima University, Japan.
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Abstract
Modern lifestyle changes may result in site-specific alterations in the skeleton. Our aim was to determine sex and age differences in regional geometry at the mid-femur. Complete cross sections from 113 individuals aged 20-97 years from a modern Australian population were obtained. A further subsample of 24, in whom the precise orientation of specimens was known, was subsequently collected. Microradiographs were made of 100-microm sections and the bone was analyzed using image processing software (Optimas, Media Cybernetics). The periosteal boundary was extracted automatically and the centroid of the periosteal outline was calculated. Fourier shape analysis was used to delineate the endocortical surface. Radial and cortical widths in each quadrant were determined. The posterior was identified by the linea aspera, and the medial and lateral were indistinguishable and therefore grouped together. For analysis, the entire sample was divided into three groups: young (20-40 years), middle (41-60 years), and old (61+ years). Raw and height-normalized values were analyzed with SPSS using t-tests, analysis of variance, and Tukey's honestly significant difference (HSD) tests. The results show that with age the femoral mid-shaft in both sexes becomes larger and more circular, with a slight shift towards the anterior. Apposition is least on the posterior and resorption greatest on the anterior, the latter being particularly evident in postmenopausal females. The greatest sex differences are seen in the middle years, lessening again in the old. We conclude that differential circumferential modeling in response to functional and postural changes occurs in both sexes with age.
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Affiliation(s)
- S A Feik
- School of Dental Science, University of Melbourne, Victoria 3000, Australia.
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Abstract
Bone is characterised by age-related morphological and histological changes. We have previously established an automated method of recording bone morphometry and histology from entire transverse sections of cortical bone. Our aim was to determine whether data acquired using this automated system were useful in the prediction of age. Ninety-six specimens of human femoral middiaphysis were studied from subjects aged 21-92 y. Equations predicting specimen age were constructed using macroscopic data (total subperiosteal area (TSPA), periosteal perimeter (PP), endosteal perimeter (EP), cortical bone area (CA) and moments of area) and microscopic data (the number, size and diversity of pores and intracortical porosity) together with sex, height and weight. Both TSPA and PP were independent predictors of age but the number of pores was not a significant predictor of age in any equation. The age predicted by these equations was inaccurate by more than 8 y in over half the subjects. We conclude that we could not predict age at a clinically acceptable level using data from our automated system. This most likely reflects an insensitivity to regional age-related changes in bone histology because we recorded data from each entire cortex. Automated bone measurement according to cortical region might be more useful in the prediction of age. The inclusion of TSPA together with PP as independent predictors of age raises the possibility that a future measure of periosteal shape at the femoral diaphysis could also be helpful in the prediction of age. The accuracy reached with the relatively simple methods described here is sufficient to encourage the development of image-analysis systems for the automatic detection of more complex features.
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Affiliation(s)
- C D Thomas
- School of Dental Science, University of Melbourne, Victoria, Australia
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Abstract
OBJECTIVES To investigate possible variation in directional material properties of dentine in relationship to tubule orientation using a new optical imaging technique. METHOD The optical imaging technique records photometrically a grid pattern formed by using a transmission electron microscope grid as a template on the polished surface of the dentine. The grid pattern is silhouetted onto the sample surface using standard techniques. Compression (c) and diametral compression (dc) tests were undertaken using a servo hydraulic testing machine (MTS model 810) acting on rectangular blocks of dentine with dimensions 1.5 x 1.0 x 1.0 mm (for c) and cylindrical samples with dimensions 2.1 mm in diameter and 1-1.5 mm thick (for dc), respectively. The samples were cut using a diamond wheel and miniature lathe and the cut surfaces polished. Images due to a changing load profile were captured and stored as digitised files on a computer for later analysis. The precision is mainly determined by the pixel resolution of the charged-coupled device camera. RESULTS Preliminary results show the value of elastic modulus of dentine (10.4 +/- 2.9 GPa) to be similar to those previously reported in the literature. Very small localised strains at the surface of a sample can be observed qualitatively and measured quantitatively by reference to the line spacing (approximately 85 microns). Maximum strength varied with tubule orientation and (compressive/tensile) stress. CONCLUSION Very small samples of dentine may be investigated for strain in more than one direction using the imaging technique described. These results may be more appropriate for finding relative directional change rather than obtaining the elastic properties of the dentine.
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Affiliation(s)
- J E Palamara
- School of Dental Science, University of Melbourne, Australia.
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Abstract
Evolutionary and population dynamics models suggest that the migration rate will affect the probability of survival in fragmented landscapes. Using data for butterfly species in the fragmented British landscape and in immediately adjoining areas of the European continent, this paper shows that species of intermediate mobility have declined most, followed by those of low mobility, whereas high-mobility species are generally surviving well. Compared to the more sedentary species, species of intermediate mobility require relatively large areas where they breed at slightly lower local densities. Intermediate mobility species have probably fared badly through a combination of metapopulation (extinction and colonization) dynamics and the mortality of migrating individuals which fail to find new habitats in fragmented landscapes. Habitat fragmentation is likely to result in the non-random extinction of populations and species characterized by different levels of dispersal, although the details are likely to depend on the taxa, habitats and regions considered.
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Affiliation(s)
- C D Thomas
- Centre for Biodiversity and Conservation, School of Biology, University of Leeds, UK.
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Affiliation(s)
- S R Bryant
- School of Biological Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UKCNY CNYCODE="GB">, , , ,
| | - C D Thomas
- Ecology and Evolution, School of Biology, University of Leeds, Leeds, LS2 9JT, UKCNY CNYCODE="GB">, , , ,
| | - J S Bale
- School of Biological Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UKCNY CNYCODE="GB">, , , ,
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Hill JK, Thomas CD, Blakeley DS. Evolution of flight morphology in a butterfly that has recently expanded its geographic range. Oecologia 1999; 121:165-170. [DOI: 10.1007/s004420050918] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Kawamura M, Thomas CD, Kawaguchi Y, Sasahara H. Lotka's law and the pattern of scientific productivity in the dental science literature. Med Inform Internet Med 1999; 24:309-15. [PMID: 10674421 DOI: 10.1080/146392399298320] [Citation(s) in RCA: 13] [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] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Statistical regularities can be observed in many natural and social phenomena. From empirical data on the authorship of scientific papers, Lotka deduced an inverse-square law: the number of authors publishing n papers is 1/n2 of those publishing one paper. The general type for the relation (1/n(c)) has a wide range of applicability to a variety of phenomena. This study examined, by means of bibliometric tools, whether Lotka's law could be applied to the literature of dental science. Data came from 20 leading dental science journals, as reported in Journal Citation Reports. The search was performed with a programme developed using Visual Basic for Applications, which counted the number of authors and analysed their contributions to the literature. Authorship for all contributions, as reported in Medline, was compiled for each of these 20 journals for the last 25 years, 1971 through 1995. The total number of authors was 43,796, responsible for 124,556 authorships. The journals published in countries other than the USA exhibited higher degrees of author concentration. The dental science literature conformed very well to Lotka's model with c = 1.95.
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Affiliation(s)
- M Kawamura
- Hiroshima University School of Dentistry, Japan
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Affiliation(s)
- M. J. R. Cowley
- Centre for Biodwersity and Conservation, School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - C. D. Thomas
- Centre for Biodwersity and Conservation, School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - J. A. Thomas
- institute of Terrestrial Ecology, FurZebrook Research Station, Mr Wareham, Dorset BH20 5AS, UK
| | - M. S. Warren
- Butterfly Conservation, PO Box 444, Wareham, Dorset BH20 5YA, UK
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Klimenko DE, Convery MA, Rowsell S, Thomas CD, Phillips SE. Crystallization and preliminary X-ray crystallographic studies of RepDC, a hybrid rolling-circle plasmid replication initiator protein. Acta Crystallogr D Biol Crystallogr 1999; 55:1076-8. [PMID: 10216311 DOI: 10.1107/s0907444999003005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The hybrid plasmid-replication initiator protein RepDC, which is a fusion of the catalytic fragment of the RepD protein and the DNA-binding fragment of the RepC protein from Staphylococcus aureus, has been successfully crystallized and X-ray data to 3.5 A have been collected on a synchrotron radiation source. Crystals belong to space group I4132 with unit-cell dimensions a = b = c = 165.1 A. The crystals are estimated to contain one protein monomer per asymmetric unit, with 55% solvent content.
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Affiliation(s)
- D E Klimenko
- Astbury Centre for Structural Molecular Biology and School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, England
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Abstract
Characteristics of microscopic structures in bone cross sections carry essential clues in age determination in forensic science and in the study of age-related bone developments and bone diseases. Analysis of bone cross sections represents a major area of research in bone biology. However, traditional approaches in bone biology have relied primarily on manual processes with very limited number of bone samples. As a consequence, it is difficult to reach reliable and consistent conclusions. In this paper we present an image processing system that uses microstructural and relational knowledge present in the bone cross section for bone image segmentation. This system automates the bone image analysis process and is able to produce reliable results based on quantitative measurements from a large number of bone images. As a result, using large databases of bone images to study the correlation between bone structural features and age-related bone developments becomes feasible.
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Affiliation(s)
- Z Q Liu
- Department of Computer Science, University of Melbourne, Parkville, Victoria, Australia
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Abstract
The matrix of human cortical bone is arranged around a network of vascular spaces (hereafter referred to as "pores"). Our aim was to investigate age-related differences in human cortical porosity (total pore area divided by cortical bone area), pore size and number, and surface to volume ratios, while adjusting for sex, height, and weight. Ninety-six specimens of entire transverse sections of human femoral diaphysis, from subjects aged 21-92 years, were examined. We used our established automated image acquisition and analysis system which measures pores from entire sections of multiple specimens of bone. Over 400,000 pores were recorded. Results showed a greater porosity in older bone (p < 0.01) but marked variation in porosity for any given age. The cohort median, of the specimen medians, of pore cross-sectional area was 2050 microns 2. Older specimens did not have more pores than younger specimens but had a greater proportion of larger pores (p < 0.05) and greater intraspecimen variation in pore size (p < 0.001). The pore surface to bone matrix volume ratio was a median 2.3 mm2/mm3. This varied more than 4-fold between individuals but did not relate to age. No simple relationships were found between any of the measured parameters and either sex, height, or weight, even after adjustment for age. We conclude that the greater porosity in older specimens is due to greater pore size rather than a larger number of pores. Age, however, explains little of the inter-individual variation in the parameters studied.
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Affiliation(s)
- M S Stein
- University of Melbourne Department of Medicine, Royal Melbourne Hospital, Australia
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Soultanas P, Dillingham MS, Papadopoulos F, Phillips SE, Thomas CD, Wigley DB. Plasmid replication initiator protein RepD increases the processivity of PcrA DNA helicase. Nucleic Acids Res 1999; 27:1421-8. [PMID: 10037801 PMCID: PMC148333 DOI: 10.1093/nar/27.6.1421] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [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: 11/13/2022] Open
Abstract
The replication initiator protein RepD encoded by the Staphylococcus chloramphenicol resistance plasmid pC221 stimulates the helicase activity of the Bacillus stearothermophilus PcrA DNA helicase in vitro. This stimulatory effect seems to be specific for PcrA and differs from the stimulatory effect of the Escherichia coli ribosomal protein L3. Whereas L3 stimulates the PcrA helicase activity by promoting co-operative PcrA binding onto its DNA substrate, RepD stimulates the PcrA helicase activity by increasing the processivity of the enzyme and enables PcrA to displace DNA from a nicked substrate. The implication of these results is that PcrA is the helicase recruited into the replisome by RepD during rolling circle replication of plasmids of the pT181 family.
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Affiliation(s)
- P Soultanas
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK andSchool of Biochemistry and Molecular Biology, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK
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Thomas CD, Glen SWT, Lewis OT, Hill JK, Blakeley DS. Population differentiation and conservation of endemic races: the butterfly, Plebejus argus. Anim Conserv 1999. [DOI: 10.1111/j.1469-1795.1999.tb00044.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Abstract
The reasons for the increase in fracture rates with age are not fully understood. It is known that there is a decrease in bone mass with a presumed loss of strength. This decrease may possibly be compensated for by changes in cross-sectional geometry. Previous studies, which have been limited by lack of information on subjects' heights and weights, were not able to resolve this issue. In this study, measurements of cross-sectional geometry (area and second moments of area) from 107 specimens of human femoral diaphysis from subjects aged 21-92 years were analysed. Mathematical models of the variation in bone geometry with age were developed. These models included the effects of sex, height and weight. Values of parameters from these models were then used in a biomechanical analysis of the static stresses at the mid-shaft of the femur. Results indicate that although there was a reduction in cortical area in old age, bone tissue was redistributed so that neither bending stresses in the coronal plane nor torsional stresses were higher in old age than in young adulthood. An additional finding was that at any age women had smaller bones, less cortical bone area and higher bone stresses than men. This finding may have some bearing on the higher fracture incidence seen in older women.
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Affiliation(s)
- M S Stein
- University of Melbourne, Department of Medicine, The Royal Melbourne Hospital, Australia
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46
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Affiliation(s)
- C D Thomas
- Department of Biochemistry & Molecular Biology, University of Leeds, U.K
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47
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Abstract
Complete cross-sections from the femoral midshaft of 180 individuals of known height and weight, aged 21-97 y, from a modern Australian population were examined using automatic video image analysis to quantify total subperiosteal porosity (TSPP). More specifically, the aim was to investigate whether age changes were similar in both sexes in (1) total subperiosteal area (TSPA), cortical area (CA) and medullary area (MA), (2) intracortical porosity (ICP), and (3) the respective contributions to TSPP made by MA and intracortical void area (ICVA). Our findings indicated that both sexes showed a significantly greater height normalised TSPA in the 70s as compared with the 20s. Males had consistently larger bones with a greater height normalised CA. In both sexes CA showed a tendency to increase till the 7th decade and then to decline, more so in females. MA approximately trebled in females and doubled in males over the age range studied. Although ICP also increased, from 4-6% in young adults to over 9% in the elderly, it showed a significant difference between the sexes only in the 3rd decade, being greater in males at this stage. By contrast, TSPP became significantly greater in females (from that recorded in the 3rd decade) by the time they reached the 50s, while in males this did not occur till the 80s. It increased from approximately 25% in young adults of both sexes to approximately 50% in females and approximately 37% in males in their 80s. However, in the elderly there was great variability in both sexes in the appearance of bones from individuals of similar chronological age. Some bones differed little from those in younger subjects, others showed greatly increased ICP, still others displayed reduced cortical widths with low ICP. The femoral midshaft resembles other skeletal sites in that age changes in TSPP are more marked in females than males.
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Affiliation(s)
- S A Feik
- School of Dental Science, University of Melbourne, Victoria, Australia.
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Nozue M, Lee I, Yuan F, Teicher BA, Brizel DM, Dewhirst MW, Milross CG, Milas L, Song CW, Thomas CD, Guichard M, Evans SM, Koch CJ, Lord EM, Jain RK, Suit HD. Interlaboratory variation in oxygen tension measurement by Eppendorf "Histograph" and comparison with hypoxic marker. J Surg Oncol 1997; 66:30-8. [PMID: 9290690 DOI: 10.1002/(sici)1096-9098(199709)66:1<30::aid-jso7>3.0.co;2-o] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [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: 02/05/2023]
Abstract
BACKGROUND AND OBJECTIVES The median of pO2 values in tumor measured by Eppendorf "Histograph" with a needle-type electrode has been used as a prognostic indicator in cancer patients. However, it is not established that a pretreatment measured pO2 value can be used as a universal predictor of local control probability, because the variation in pO2 values, especially in hypoxic tissue, among institutes may not allow comparison of measured "absolute pO2 values." The purpose of this study was to examine the variation in oxygen tension measurement by Eppendorf "Histograph" among six laboratories using a single batch of mice and tumors and the same detailed protocol. These results were also compared to the immunohistochemical staining of 2-nitromidazole adducts. METHODS C3H mice bearing FSaII murine fibrosarcoma subcutaneously were shipped to all laboratories, and the oxygen status in tumors and in normal subcutis was examined using Eppendorf "Histograph" and immunohistochemical hypoxic marker. RESULTS All laboratories showed that the FSaII tumor was hypoxic with at least 77% of measured points under 10 mmHg in pO2 and with a median pO2 value less than that of normal subcutis. These results were further confirmed immunohistochemically. These findings are interpreted as evidence that the pO2 values measured by Eppendorf "Histograph" can be useful. However, the median values of tumor pO2 varied from 1.5 mmHg to 5.6 mmHg among the laboratories, and pO2 of normal subcutis also varied from 28 mmHg to 38 mmHg. There were also significant differences in hypoxic fraction, defined as the fraction under a given oxygen partial pressure (i.e., under 2.5, 5, or 10 mmHg), among institutes. CONCLUSIONS Caution needs to be exercised in using the absolute, median, or distribution of pO2 values measured by the Eppendorf "Histograph" to compare the data between laboratories or to predict the radiation response in an individual subject.
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Affiliation(s)
- M Nozue
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
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Abstract
OBJECTIVE In 1991 the Oregon Board of Medical Examiners initiated a separate category for the complaint of sexual misconduct. Investigated complaints of sexual misconduct brought to the Oregon Board of Medical Examiners were analyzed for the years 1991 to 1995 to serve as a baseline. Comparison was made to the Federation of State Medical Boards sexual misconduct data for 1991 and 1992. STUDY DESIGN One hundred complaints brought against 80 licensees were evaluated by practitioner's degree, age group, sex, specialty, and disposition of complaints for the years 1991 to 1995. The allegations were classified into behavior categories of sexual impropriety, sexual transgression, and sexual violations. RESULTS Sexual misconduct was the allegation in 5.9% of the complaints investigated for the study period. Oregon had more sexual misconduct complaints than the average reported to the Federation of State Medical Boards for the years 1991 and 1992. Most (72%) complaints came from the patients or their families. Two female physicians (2.4%) had sexual boundary complaints. Sexual misconduct complaints increased by a risk ratio of 1.44 with advancing age by decades. Allegations classified into behavior categories according to severity revealed 39% sexual impropriety, 31% sexual transgression, and 30% sexual violation. Reportable disciplinary actions occurred only with multiple allegations of sexual impropriety (6.5%) and for sexual transgression (27%) whereas sexual violation allegations often had one complainant but there were 54% reportable disciplinary actions. Family practice, obstetrics and gynecology, and psychiatry had the highest incidence of sexual misconduct complaints whereas psychiatry and obstetrics and gynecology had the highest incidence of reportable disciplinary actions. Twenty-five percent of the closed cases resulted in reportable disciplinary actions. This analysis is discussed in relationship to legal and ethical issues and the goal of zero tolerance. CONCLUSIONS Oregon has a higher percentage of sexual misconduct complaints than the average for 42 states reporting to the Federation of State Medical Boards for the years 1991 and 1992. Analysis of the Oregon Board's experience for the study years will provide a baseline for future evaluation and as an educational resource for the Oregon Board of Medical Examiners and professional and specialty societies. Ethical standards, the reporting and investigative processes, and the legal framework are in place and lessen the incidence of sexual misconduct and work toward zero tolerance.
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Affiliation(s)
- J A Enbom
- Oregon Board of Medical Examiners, Portland 97201, USA
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Sheridan CS, Thomas CD, Clement JG. Quantification of ethnic differences in facial profile. Aust Orthod J 1997; 14:218-24. [PMID: 9528404] [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: 02/07/2023]
Abstract
The concept of facial aesthetics is becoming increasingly important and with the expanding application of orthodontic, orthognathic, plastic and reconstructive techniques to patients from continually diversifying ethnic backgrounds, it is timely that more elaborate methods for the evaluation of facial form are adopted. The aim of the present study was to further investigate the use of Fourier shape analysis in the quantification of facial profile and to investigate differences between racial groups. One hundred and twenty-two undergraduate dental students were photographed and surveyed for information pertaining to ethnic origin. Student's t-tests revealed significant differences (p < 0.05) in higher-order (fourth- and above) Fourier harmonics between male and female profiles, as well as between intervention and non-intervention groups. A comparison of multiple means test revealed significant differences (p < 0.05) in the third-order Fourier harmonic (vertex projection) between the Asian group and three other groups--Anglo-Celtic, Eastern European and Western European. Differences correlated with convexity in the lower third of the face, which was demonstrated by Fourier reconstruction.
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Affiliation(s)
- C S Sheridan
- School of Dental Science, University of Melbourne, Australia
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