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Nally MC, Farlow E, Keen R. PC132. Using Cephalic or Axillary Vein to Femoral Vein Bypass as Surgical Treatment of Symptomatic Venous Hypertension in Dialysis Patients With Central Venous Occlusion. J Vasc Surg 2016. [DOI: 10.1016/j.jvs.2016.03.325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Machado A, Keen R. Learning to Time (LET) or Scalar Expectancy Theory (SET)? A Critical Test of Two Models of Timing. Psychol Sci 2016. [DOI: 10.1111/1467-9280.00152] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Two theories of timing, scalar expectancy theory (SET) and learning to time (LeT), make substantially different assumptions about what animals learn in temporal tasks. In a test of these assumptions, pigeons learned two discriminations: On Type 1 trials, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; on Type 2 trials, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then, two psychometric functions were obtained by presenting them with intermediate durations (1 to 4 s and 4 to 16 s). The two functions did not superpose, and most bisection points were not at the geometric mean of the training stimuli (contra SET); for most birds, the function for Type 2 trials was to the left of the function for Type 1 trials (contra LeT). Finally, the birds were exposed to signals ranging from 1 to 16 s and given a choice between novel key combinations (e.g., red vs. blue). The results with the novel key combinations were always closer to LeT's than to SET's predictions. Observations of the birds' behavior also suggest that, more than being a mere expression of an internal clock, behavior constitutes the clock.
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Buckley K, Kerns JG, Gikas PD, Birch HL, Vinton J, Keen R, Parker AW, Matousek P, Goodship AE. Measurement of abnormal bone composition in vivo using noninvasive Raman spectroscopy. ACTA ACUST UNITED AC 2014. [DOI: 10.1038/bonekey.2014.97] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kerns JG, Gikas PD, Buckley K, Shepperd A, Birch HL, McCarthy I, Miles J, Briggs TWR, Keen R, Parker AW, Matousek P, Goodship AE. Evidence from Raman spectroscopy of a putative link between inherent bone matrix chemistry and degenerative joint disease. Arthritis Rheumatol 2014; 66:1237-46. [PMID: 24470432 PMCID: PMC4158861 DOI: 10.1002/art.38360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 01/09/2014] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Osteoarthritis (OA) is a common debilitating disease that results in degeneration of cartilage and bone in the synovial joints. Subtle changes in the molecular structure of the subchondral bone matrix occur and may be associated with cartilage changes. The aim of this study was to explore whether the abnormal molecular changes observed in the matrix of OA subchondral bone can be identified with Raman spectroscopy. METHODS Tibial plateaus from patients undergoing total knee replacement for OA (n = 10) were compared with healthy joints from patients undergoing leg amputation (n = 5; sex- and laterality-matched) and with non-OA cadaveric knee specimens (n = 5; age-matched). The samples were analyzed with Raman spectroscopy, peripheral quantitative computed tomography, and chemical analysis to compare changes in defined load-bearing sites in both the medial and lateral compartments. RESULTS OA subchondral bone matrix changes were detected by Raman spectroscopy. Within each cohort, there was no spectral difference in bone matrix chemistry between the medial and lateral compartments, whereas a significant spectral difference (P < 0.001) was observed between the non-OA and OA specimens. Type I collagen chain ratios were normal in the non-OA specimens but were significantly elevated in the OA specimens. CONCLUSION In comparing the results of Raman spectroscopy with those obtained by other standard techniques, these findings show, for the first time, that subchondral bone changes, or inherent differences, exist in both the medial and lateral (beneath intact cartilage) compartments of OA knees. The development of Raman spectroscopy as a screening tool, based on molecular-specific modifications in bone, would facilitate the identification of clinical disease, including early molecular changes.
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Zeggini E, Panoutsopoulou K, Southam L, Rayner NW, Day-Williams AG, Lopes MC, Boraska V, Esko T, Evangelou E, Hoffman A, Houwing-Duistermaat JJ, Ingvarsson T, Jonsdottir I, Jonnson H, Kerkhof HJ, Kloppenburg M, Bos SD, Mangino M, Metrustry S, Slagboom PE, Thorleifsson G, Raine EVA, Ratnayake M, Ricketts M, Beazley C, Blackburn H, Bumpstead S, Elliott KS, Hunt SE, Potter SC, Shin SY, Yadav VK, Zhai G, Sherburn K, Dixon K, Arden E, Aslam N, Battley PK, Carluke I, Doherty S, Gordon A, Joseph J, Keen R, Koller NC, Mitchell S, O'Neill F, Paling E, Reed MR, Rivadeneira F, Swift D, Walker K, Watkins B, Wheeler M, Birrell F, Ioannidis JPA, Meulenbelt I, Metspalu A, Rai A, Salter D, Stefansson K, Stykarsdottir U, Uitterlinden AG, van Meurs JBJ, Chapman K, Deloukas P, Ollier WER, Wallis GA, Arden N, Carr A, Doherty M, McCaskie A, Willkinson JM, Ralston SH, Valdes AM, Spector TD, Loughlin J. Identification of new susceptibility loci for osteoarthritis (arcOGEN): a genome-wide association study. Lancet 2012; 380:815-23. [PMID: 22763110 PMCID: PMC3443899 DOI: 10.1016/s0140-6736(12)60681-3] [Citation(s) in RCA: 278] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Osteoarthritis is the most common form of arthritis worldwide and is a major cause of pain and disability in elderly people. The health economic burden of osteoarthritis is increasing commensurate with obesity prevalence and longevity. Osteoarthritis has a strong genetic component but the success of previous genetic studies has been restricted due to insufficient sample sizes and phenotype heterogeneity. METHODS We undertook a large genome-wide association study (GWAS) in 7410 unrelated and retrospectively and prospectively selected patients with severe osteoarthritis in the arcOGEN study, 80% of whom had undergone total joint replacement, and 11,009 unrelated controls from the UK. We replicated the most promising signals in an independent set of up to 7473 cases and 42,938 controls, from studies in Iceland, Estonia, the Netherlands, and the UK. All patients and controls were of European descent. FINDINGS We identified five genome-wide significant loci (binomial test p≤5·0×10(-8)) for association with osteoarthritis and three loci just below this threshold. The strongest association was on chromosome 3 with rs6976 (odds ratio 1·12 [95% CI 1·08-1·16]; p=7·24×10(-11)), which is in perfect linkage disequilibrium with rs11177. This SNP encodes a missense polymorphism within the nucleostemin-encoding gene GNL3. Levels of nucleostemin were raised in chondrocytes from patients with osteoarthritis in functional studies. Other significant loci were on chromosome 9 close to ASTN2, chromosome 6 between FILIP1 and SENP6, chromosome 12 close to KLHDC5 and PTHLH, and in another region of chromosome 12 close to CHST11. One of the signals close to genome-wide significance was within the FTO gene, which is involved in regulation of bodyweight-a strong risk factor for osteoarthritis. All risk variants were common in frequency and exerted small effects. INTERPRETATION Our findings provide insight into the genetics of arthritis and identify new pathways that might be amenable to future therapeutic intervention. FUNDING arcOGEN was funded by a special purpose grant from Arthritis Research UK.
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Weiler R, Keen R, Wolman R. Changes in bone turnover markers during the close season in elite football (soccer) players. J Sci Med Sport 2012; 15:255-8. [DOI: 10.1016/j.jsams.2011.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 09/16/2011] [Accepted: 09/20/2011] [Indexed: 10/15/2022]
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Lipe AW, Ward KC, Watson AT, Manley K, Keen R, Kelly J, Clemmer J. The effects of an arts intervention program in a community mental health setting: A collaborative approach. ARTS IN PSYCHOTHERAPY 2012. [DOI: 10.1016/j.aip.2011.11.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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McCarthy ID, Bloomer Z, Gall A, Keen R, Ferguson-Pell M. Changes in the structural and material properties of the tibia in patients with spinal cord injury. Spinal Cord 2011; 50:333-7. [PMID: 22124349 DOI: 10.1038/sc.2011.143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
STUDY DESIGN A cross-sectional study. OBJECTIVES To measure the change of structural and material properties at different sites of the tibia in spinal cord-injured patients using peripheral quantitative computerised tomography (pQCT). SETTING Orthopaedic research centre (UK). METHODS Thirty-one subjects were measured--eight with acute spinal cord injury (SCI), nine with chronic SCI and fourteen able-bodied controls. pQCT scans were performed at 2% (proximal), 34% (diaphyseal) and 96% (distal) along the tibia from the tibial plateau. Structural measures of bone were calculated, and volumetric bone mineral density (vBMD) was also measured at all three levels. Muscle cross-sectional area was measured at the diaphyseal level. RESULTS Structurally, there were changes in the cortical bone; in the diaphysis, the shape of the cross-section changed to offer less resistance to AP bending, and the cross-sectional area of the cortical shell decreased both proximally and distally. There were corresponding changes in vBMD in the anterior aspect of the cortical diaphysis, as well as proximal and distal trabecular bone. Changes in muscle occurred more rapidly than changes in bone. CONCLUSION There were clear changes of both structure and material at all three levels of the tibia in chronic SCI patients. These changes were consistent with specific adaptations to reduced local mechanical loading conditions. To assess fracture risk in SCI and also to monitor the effect of therapeutic interventions, the structure of the bone should be considered in addition to trabecular bone mineral density.
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Panoutsopoulou K, Southam L, Elliott KS, Wrayner N, Zhai G, Beazley C, Thorleifsson G, Arden NK, Carr A, Chapman K, Deloukas P, Doherty M, McCaskie A, Ollier WER, Ralston SH, Spector TD, Valdes AM, Wallis GA, Wilkinson JM, Arden E, Battley K, Blackburn H, Blanco FJ, Bumpstead S, Cupples LA, Day-Williams AG, Dixon K, Doherty SA, Esko T, Evangelou E, Felson D, Gomez-Reino JJ, Gonzalez A, Gordon A, Gwilliam R, Halldorsson BV, Hauksson VB, Hofman A, Hunt SE, Ioannidis JPA, Ingvarsson T, Jonsdottir I, Jonsson H, Keen R, Kerkhof HJM, Kloppenburg MG, Koller N, Lakenberg N, Lane NE, Lee AT, Metspalu A, Meulenbelt I, Nevitt MC, O'Neill F, Parimi N, Potter SC, Rego-Perez I, Riancho JA, Sherburn K, Slagboom PE, Stefansson K, Styrkarsdottir U, Sumillera M, Swift D, Thorsteinsdottir U, Tsezou A, Uitterlinden AG, van Meurs JBJ, Watkins B, Wheeler M, Mitchell S, Zhu Y, Zmuda JM, Zeggini E, Loughlin J. Insights into the genetic architecture of osteoarthritis from stage 1 of the arcOGEN study. Ann Rheum Dis 2010; 70:864-7. [PMID: 21177295 PMCID: PMC3070286 DOI: 10.1136/ard.2010.141473] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Objectives The genetic aetiology of osteoarthritis has not yet been elucidated. To enable a well-powered genome-wide association study (GWAS) for osteoarthritis, the authors have formed the arcOGEN Consortium, a UK-wide collaborative effort aiming to scan genome-wide over 7500 osteoarthritis cases in a two-stage genome-wide association scan. Here the authors report the findings of the stage 1 interim analysis. Methods The authors have performed a genome-wide association scan for knee and hip osteoarthritis in 3177 cases and 4894 population-based controls from the UK. Replication of promising signals was carried out in silico in five further scans (44 449 individuals), and de novo in 14 534 independent samples, all of European descent. Results None of the association signals the authors identified reach genome-wide levels of statistical significance, therefore stressing the need for corroboration in sample sets of a larger size. Application of analytical approaches to examine the allelic architecture of disease to the stage 1 genome-wide association scan data suggests that osteoarthritis is a highly polygenic disease with multiple risk variants conferring small effects. Conclusions Identifying loci conferring susceptibility to osteoarthritis will require large-scale sample sizes and well-defined phenotypes to minimise heterogeneity.
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Roemer FW, Kassim Javaid M, Guermazi A, Thomas M, Kiran A, Keen R, King L, Arden NK. Anatomical distribution of synovitis in knee osteoarthritis and its association with joint effusion assessed on non-enhanced and contrast-enhanced MRI. Osteoarthritis Cartilage 2010; 18:1269-74. [PMID: 20691796 DOI: 10.1016/j.joca.2010.07.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 06/07/2010] [Accepted: 07/20/2010] [Indexed: 02/02/2023]
Abstract
PURPOSE To describe the anatomical distribution of synovitis and its association with joint effusion on non-enhanced and contrast-enhanced (CE) MRI in patients with knee osteoarthritis (OA). METHODS Baseline MRI was performed at 1.5T using axial proton density (PD)-weighted (w) fat suppressed (fs) and axial and sagittal T1-w fs CE sequences. Synovial enhancement was scored in nine articular subregions. Maximum synovial enhancement was grouped as absent (0), equivocal (1) and definite (2 and 3). Effusion was scored from 0 to 3 on the axial sequences. We described the anatomical distribution of synovitis, its association with effusion and compared assessment of effusion on T1-w fs CE and PD fs sequences. RESULTS 111 subjects were included and examined by MRI. 89.2% of knees exhibited at least one subregion with a minimum grade 2 and 39.6% at the maximum of a grade 3. The commonest sites for definite synovitis were posterior to the posterior cruciate ligament (PCL) in 71.2% and in the suprapatellar region in 59.5% of all knees. On T1-w fs CE, 73.0% of knees showed any effusion. Definite synovitis in at least one location was present in 96.3% knees with an effusion and in 70.0% without an effusion. Higher grades of effusion were scored on the PD fs sequence. CONCLUSION Definite synovitis was present in the majority of knees with or without effusion with the commonest sites being posterior to the PCL and in the suprapatellar recess. Joint effusion as measured on PD fs images does not only represent effusion but also synovial thickening.
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Lyritis G, Marin F, Barker C, Pfeifer M, Farrerons J, Brixen K, del Pino J, Keen R, Nickelsen TN. Back pain during different sequential treatment regimens of teriparatide: results from EUROFORS. Curr Med Res Opin 2010; 26:1799-807. [PMID: 20482322 DOI: 10.1185/03007995.2010.488516] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To investigate changes in back pain in postmenopausal women with severe osteoporosis who received teriparatide for 24 months or switched at 12 months to raloxifene or no active treatment. STUDY DESIGN AND METHODS This prospective, controlled, randomised, open-label, 2-year study enrolled 868 postmenopausal women with osteoporosis and a recent fragility fracture. After 12 months of teriparatide (20 microg/day), 507 patients were randomised to further teriparatide (n = 305), raloxifene 60 mg/day (n = 100), or no active treatment (n = 102) for another 12 months (substudy 1); in substudy 2, 199 patients continued teriparatide. All received calcium and vitamin D supplementation. Back pain was self-assessed by patients using a visual analogue scale (0-100 mm). Changes in back pain were analysed using a mixed model for repeated measures. RESULTS During year 1, back pain decreased from a mean (SD) of 48.9 mm (24.0) at baseline by 11.5 mm (p < 0.001) in the total study population. In substudy 1, mean change in back pain from month 12 (randomisation) to 24 months was -2.2, -4.4 and +0.7 mm in the teriparatide (p = 0.076), raloxifene (p = 0.041), and no active treatment groups (p = 0.751). There were no between-group differences from randomization to 18 or 24 months. In a sensitivity analysis excluding patients with low baseline back pain (VAS < 30 mm), mean change from randomisation to endpoint was significant for teriparatide (-3.9 mm, p = 0.006) and raloxifene (-6.3 mm, p = 0.018) groups. Subgroup analyses of 503 patients who received teriparatide for up to 2 years showed that patients with a recent vertebral fracture had a greater decrease in back pain than those without (p < 0.05). Those with and without mild back pain (>or=30 mm), and those with and without severe back pain (>or=60 mm) at baseline all had a statistically significant reduction in back pain after 24 months (p < 0.05). CONCLUSIONS Teriparatide treatment is associated with significant reductions in back pain regardless of the presence of recent vertebral fracture. These results need to be considered with caution due to the open-label design of the study.
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El Miedany Y, El Gaafary M, Youssef S, Toth M, Weightman J, Kelly M, Johnston E, Stone A, Harrison P, Bartholomew P, Kelly C, Vagadia V, Tuck S, Al-Shakarchi I, Louise Dolan A, Bridges MJ, Ruddick S, Bracewell C, Wright D, Aspray T, Hynes GM, Jameson K, Aihie Sayer A, Cooper C, Dennison E, Robinson S, Tull TJ, Fisher BA, Jenabzadeh R, Cobb JP, Abraham S, Hynes GM, Jameson K, Harvey N, Aihie Sayer A, Cooper C, Dennison E, Cheah J, Stacpoole S, Heaney D, Duncan J, Roshandel D, Holliday K, Pye SR, Boonen S, Borghs H, Vanderschueren D, Adams JE, Ward KA, Finn JD, Huhtaniemi IT, Silman AJ, Wu FC, Thomson W, O'Neill TW, White S, Shaw S, Short C, Gilleece Y, Fisher M, Walker-Bone K, Narshi CB, Martin R, Mitchell K, Keen R, Bridges MJ, Ruddick S, El Miedany Y, Toth M, Youssef S, El Gaafary M, Alhambra DP, Azagra R, Duro GE, Aguye A, Zwart M, Javaid KM. Osteoporosis and Metabolic Bone Disease [127-142]: 127. Osteoporosis, Falls and Fractures: Three Confounders in One Equation. Development and Validity of a New form for Assessment of Patients Referred for Dxa Scanning. Rheumatology (Oxford) 2010. [DOI: 10.1093/rheumatology/keq723] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Farrow EG, Davis SI, Ward LM, Summers LJ, Bubbear JS, Keen R, Stamp TC, Baker LRI, Bonewald LF, White KE. Molecular analysis of DMP1 mutants causing autosomal recessive hypophosphatemic rickets. Bone 2009; 44:287-94. [PMID: 19007919 PMCID: PMC2669955 DOI: 10.1016/j.bone.2008.10.040] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 09/10/2008] [Accepted: 10/06/2008] [Indexed: 11/16/2022]
Abstract
We previously demonstrated that the mutations Met1Val (M1V) and the deletion of nucleotides 1484-1490 (1484-1490del) in Dentin matrix protein-1 (DMP1) cause the novel disorder autosomal recessive hypophosphatemic rickets (ARHR), which is associated with elevated fibroblast growth factor-23 (FGF23). To further understand the role of DMP1 in ARHR, we undertook molecular genetic and in vitro expression studies. First, we examined a kindred with a severe hypophosphatemic rickets phenotype and recessive inheritance. Analyses of this family demonstrated that the affected members had elevated serum FGF23 and carried a large, biallelic deletion that removed the majority of DMP1. At a minimum, this deletion encompassed 49 kb between DMP1 exon 3 and an intergenic region 5' to the next telomeric gene, integrin-binding sialoprotein (IBSP). We next performed immunofluorescent studies in cells to understand the effects of the known ARHR mutations on DMP1 cellular processing. These analyses showed that the M1V DMP1 mutant was not sorted to the trans-Golgi network (TGN) and secretory pathway, but filled the entire cytoplasm. In contrast, the 1484-1490del mutant localized to the TGN and was secreted, similar to wild type DMP1. The 1484-1490del mutation replaces the DMP1 18 C-terminal amino acids with 33 non-native residues. Truncation of wild type DMP1 by these native 18 residues followed by Western blot and confocal microscopic analyses demonstrated a wild type expression pattern when compared with the 1484-1490del mutant, indicating that the last 18 residues are not critical for cellular trafficking, but that the 33 additional residues arising from the 1484-1490del mutation likely compromise DMP1 processing. The relationship between DMP1 and FGF23 is unclear. To test endogenous DMP1 response to serum metabolites that also regulate FGF23, UMR-106 cells were treated with 1,25(OH)(2) vitamin D (1x10(-7) M) and showed a 12-fold increase in DMP1 mRNA and protein at 24 h. In summary, we have identified a novel DMP1 deletion as the cause of ARHR, as well as demonstrated that the ARHR mutations alter DMP1 cellular processing, and that DMP1 can be regulated by vitamin D. Taken together, this work expands our understanding of the genetic and molecular mechanisms associated with DMP1 alterations causing ARHR.
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Swanton J, Simister R, Altmann D, Watts H, Keen R, Duncan JS, Koepp MJ. Bone mineral density in institutionalised patients with refractory epilepsy. Seizure 2007; 16:538-41. [PMID: 17408980 DOI: 10.1016/j.seizure.2007.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 03/07/2007] [Accepted: 03/12/2007] [Indexed: 11/18/2022] Open
Abstract
Bone mineral density (BMD) and content (BMC) were measured in 208 institutionalised patients with refractory epilepsy. BMD was in the osteoporotic range in 43% of males and 21% of females. BMC was reduced only in male patients. Apart from age and gender, no other factor or specific AED was particularly associated with reduced BMD or BMC. This study indicates the magnitude of the problem of bone disease in refractory epilepsy, in particular affecting young and male patients with chronic epilepsy.
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Abstract
Osteoporosis is a serious public health issue, affecting up to 1 in 2 women and 1 in 5 men over the age of 50 years. The common osteoporotic fractures occur at the spine, wrist and hip. For the patient affected by osteoporosis, these fractures are associated with significant morbidity and, in the case of hip and spine fractures, an excess mortality. The treatment of osteoporotic fractures is also associated with a significant healthcare cost for society. Currently, measurement of bone mineral density using dual energy X-ray absorptiometry is the gold standard for the diagnosis of osteoporosis. In the future, however, assessment of fracture risk will be based on algorithms incorporating clinical risk factors and bone density measurements, where appropriate. The goal of treatment is to reduce the risk of future fracture. Patients at high risk for fracture should be assessed and screened to exclude secondary causes for osteoporosis. Bisphosphonates (alendronate, etidronate, ibandronate, risedronate) are the first-line therapy for the majority of patients and these treatments can be given either orally or intravenously. Alternative treatment options include strontium ranelate and raloxifene. Anabolic therapy with parathyroid hormone can be considered for patients with severe disease. These patients will often require referral for specialist assessment and monitoring. All patients at risk of developing osteoporosis should be given lifestyle advice regarding dietary intake of calcium and vitamin D and regular weight-bearing exercise.
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Keen R, Jodar E, Iolascon G, Kruse HP, Varbanov A, Mann B, Gold DT. European women's preference for osteoporosis treatment: influence of clinical effectiveness and dosing frequency. Curr Med Res Opin 2006; 22:2375-81. [PMID: 17257451 DOI: 10.1185/030079906x154079] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To determine participant preference for weekly versus monthly bisphosphonate therapy for osteoporosis after being informed about differences in fracture efficacy. DESIGN 20-minute, semi-structured, face-to-face or telephone interviews. Two bisphosphonate choices were presented on the basis of block randomization: weekly therapy with proven efficacy to reduce fracture risk at the spine and hip, or monthly therapy with proven efficacy to reduce fracture risk at the spine but not the hip. SUBJECTS Women from the UK, Germany, France, Spain and Italy, with postmenopausal osteoporosis and aged > or = 55 years. Fifty percent were currently taking a weekly bisphosphonate; 50% had no history of taking any bisphosphonate. MEASURES An efficacy rating scale and an intention-to-use rating scale were developed for this study. The primary endpoint was preference for weekly or monthly therapy. Reasons for preference were recorded. RESULTS A preference was recorded for 1248 women (1253 were recruited). More women preferred weekly to monthly therapy (82% vs. 18%, respectively; p < 0.001). Among women who preferred weekly therapy, efficacy was the most commonly cited reason (65%). Ninety-two percent of the total cohort rated the efficacy of the weekly therapy as 'excellent/good' versus 38% for monthly (p < 0.001). Sixty-nine percent intended to use weekly bisphosphonates compared with 34% for monthly (p < 0.001). CONCLUSIONS When informed about differences in fracture efficacy in weekly and monthly bisphosphonates, a significantly greater proportion (82%) of women preferred a weekly bisphosphonate with proven fracture efficacy at the spine and hip over a monthly bisphosphonate with proven fracture efficacy only at the spine.
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Reid DM, Mackay I, Wilkinson S, Miller C, Schuette DG, Compston J, Cooper C, Duncan E, Galwey N, Keen R, Langdahl B, McLellan A, Pols H, Uitterlinden A, O'Riordan J, Wass JAH, Ralston SH, Bennett ST. Cross-calibration of dual-energy X-ray densitometers for a large, multi-center genetic study of osteoporosis. Osteoporos Int 2006; 17:125-32. [PMID: 16136277 DOI: 10.1007/s00198-005-1936-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Accepted: 04/18/2005] [Indexed: 11/25/2022]
Abstract
Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Bone mineral density (BMD) is the most important determinant of osteoporotic fracture risk, but the genes responsible for BMD regulation and fracture are incompletely defined. To enable multi-center studies to examine the genetic influences on BMD there is a requirement to standardize measurements across different manufacturers of bone densitometers, different versions of machines and different normative ranges. This paper describes a method developed to allow near-identical subjects with low age-adjusted BMD (based on Z-scores) to be recruited in 17 centers using 27 different densitometers. Cross-calibration was based on measurements using a European spine phantom circulated to all centers and measured ten times on each individual machine. From theses values an individual exponential curve, based on nominal versus observed BMD, was derived for each machine. As expected, there were large and significant variations in nominal BMD values, not only between scanners from different manufacturers but also between different versions of scanners from the same manufacturer. Hologic scanners tended to underestimate the nominal BMD, while Lunar scanners overestimated the value. Norland scanners gave mixed values over estimating BMD at the lower nominal value (0.5 g/cm2) while underestimating the value at the higher value (1.5 g/cm2). The validity of the exponential equations was tested using hip and spine measurements on 991 non-proband women from a familial osteoporosis study (FAMOS). After cross-calibration there was a considerable reduction in variation between machines. This observation, coupled with the absence of a similar reduction in variation attributable to a linear regression on age, demonstrated the validity of the cross-calibration approach. Use of the cross-calibration curves along with a standard normative range (in the case of this study, the Hologic normative range) allowed age-specific Z-scores to be used as an inclusion criterion in this genetic study, a method that will be useful for other trials where age-specific BMD inclusion criteria are required.
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Abstract
The procedures for classical and operant conditioning, and for many timing procedures, involve the delivery of reinforcers that may be related to the time of previous reinforcers and responses, and to the time of onsets and terminations of stimuli. The behavior resulting from such procedures can be described as bouts of responding that occur in some pattern at some rate. A packet theory of timing and conditioning is described that accounts for such behavior under a wide range of procedures. Applications include the food searching by rats in Skinner boxes under conditions of fixed and random reinforcement, brief and sustained stimuli, and several response-food contingencies. The approach is used to describe how multiple cues from reinforcers and stimuli combine to determine the rate and pattern of response bouts.
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Keen R. Casebook: osteoporosis. THE PRACTITIONER 2005; 249:639-43. [PMID: 16163973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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70
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Ralston SH, Galwey N, MacKay I, Albagha OME, Cardon L, Compston JE, Cooper C, Duncan E, Keen R, Langdahl B, McLellan A, O'Riordan J, Pols HA, Reid DM, Uitterlinden AG, Wass J, Bennett ST. Loci for regulation of bone mineral density in men and women identified by genome wide linkage scan: the FAMOS study. Hum Mol Genet 2005; 14:943-51. [PMID: 15746152 DOI: 10.1093/hmg/ddi088] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Osteoporosis is a common disease with a strong genetic component, characterized by reduced bone mass and an increased risk of fracture. Bone mineral density (BMD) is a highly heritable trait and a key determinant of osteoporotic fracture risk, but the genes responsible are incompletely defined. Here, we identified quantitative trait loci (QTL) for regulation of BMD by a genome wide scan involving 3691 individuals from 715 families, who were selected because of reduced BMD values at the lumbar spine (LS-BMD) or femoral neck (FN-BMD) in probands. Linkage analysis was conducted in the study group as a whole with correction for age, gender, weight and height. Further analyses were conducted for men and women separately to identify gender-specific QTL and for those under and over the age of 50 years to distinguish QTL for peak bone mass from those that influence bone mass in older people. No regions of suggestive or significant linkage were identified when data from all subjects were analyzed together. On subgroup analysis, however, we identified a significant QTL for FN-BMD on chromosome 10q21 (LOD score +4.42; men < or =50 years) and two suggestive QTL for LS-BMD on chromosomes 18p11 (LOD score +2.83; women >50 years) and 20q13 (LOD score +3.20; women < or =50 years). We identified five other QTL for BMD with LOD scores of greater than +2.20 on chromosomes 3q25, 4q25, 7p14, 16p13 and 16q23. This study provides evidence for gender-specific, site-specific and age-specific QTL, which regulate BMD in humans, and illustrates the importance of conducting subgroup analysis to detect these loci.
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Keen R, Macinnis M, Guilhardi P, Chamberland K, Church R. The lack of behavioral effects of fenbendazole: a medication for pinworm infection. CONTEMPORARY TOPICS IN LABORATORY ANIMAL SCIENCE 2005; 44:17-23. [PMID: 15773771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Pinworm infection in rodent laboratories is common and often treated with fenbendazole, which is effective and has a low toxicity level. However, very little is known about the behavioral effects of the drug. The purpose of this study was to determine the behavioral effects of fenbendazole on rats tested by using various conditioning and timing procedures. These behavioral effects were examined both between animals (i.e., control versus medicated treatments) and within animals (baseline-treatment-baseline design). Fenbendazole reduced the detection of pinworm eggs, and it had no significant behavioral effects across multiple levels of analysis (e.g., from overall response rates to response patterns to interresponse intervals). All behavioral differences (e.g., discrimination ratios) were a result of task variables. These results suggest that behavioral studies are unlikely to be influenced by fenbendazole treatment given before or during a study.
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Hoffberger JD, Rossi H, Keen R, Savage EB. Penetrating trauma to the aortic arch: a case report. ACTA ACUST UNITED AC 2005; 58:381-3. [PMID: 15706206 DOI: 10.1097/01.ta.0000085851.74222.90] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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73
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Koay MA, Woon PY, Zhang Y, Miles LJ, Duncan EL, Ralston SH, Compston JE, Cooper C, Keen R, Langdahl BL, MacLelland A, O'Riordan J, Pols HA, Reid DM, Uitterlinden AG, Wass JAH, Brown MA. Influence of LRP5 polymorphisms on normal variation in BMD. J Bone Miner Res 2004; 19:1619-27. [PMID: 15355556 DOI: 10.1359/jbmr.040704] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Revised: 01/15/2004] [Accepted: 05/18/2004] [Indexed: 11/18/2022]
Abstract
UNLABELLED Genetic studies based on cohorts with rare and extreme bone phenotypes have shown that the LRP5 gene is an important genetic modulator of BMD. Using family-based and case-control approaches, this study examines the role of the LRP5 gene in determining normal population variation of BMD and describes significant association and suggestive linkage between LRP5 gene polymorphisms and BMD in >900 individuals with a broad range of BMD. INTRODUCTION Osteoporosis is a common, highly heritable condition determined by complex interactions of genetic and environmental etiologies. Genetic factors alone can account for 50-80% of the interindividual variation in BMD. Mutations in the LRP5 gene on chromosome 11q12-13 have been associated with rare syndromes characterized by extremely low or high BMD, but little is known about the contribution of this gene to the development of osteoporosis and determination of BMD in a normal population. MATERIALS AND METHODS To examine the entire spectrum of low to high BMD, 152 osteoporotic probands, their families (597 individuals), and 160 women with elevated BMD (T score > 2.5) were recruited. BMD at the lumbar spine, femoral neck, and hip were measured in each subject using DXA. RESULTS PAGE sequencing of the LRP5 gene revealed 10 single nucleotide polymorphisms (SNPs), 8 of which had allele frequencies of >5%, in exons 8, 9, 10, 15, and 18 and in introns 6, 7, and 21. Within families, a strong association was observed between an SNP at nucleotide C171346A in intron 21 and total hip BMD (p < 1 x 10(-5) in men only, p = 0.0019 in both men and women). This association was also observed in comparisons of osteoporotic probands and unrelated elevated BMD in women (p = 0.03), along with associations with markers in exons 8 (C135242T, p = 0.007) and 9 (C141759T, p = 0.02). Haplotypes composed of two to three of the SNPs G121513A, C135242T, G138351A, and C141759T were strongly associated with BMD when comparing osteoporotic probands and high BMD cases (p < 0.003). An SNP at nucleotide C165215T in exon 18 was linked to BMD at the lumbar spine, femoral neck, and total hip (parametric LOD scores = 2.8, 2.5, and 2.2 and nonparametric LOD scores = 0.3, 1.1, and 2.2, respectively) but was not genetically associated with BMD variation. CONCLUSION These results show that common LRP5 polymorphisms contribute to the determination of BMD in the general population.
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Patel S, Dolan AL, Hajela V, Cheung N, Keen R. Does giving osteoporosis patient information to women who have had a fracture improve access to health care? Rheumatology (Oxford) 2004; 43:387-9. [PMID: 14963206 DOI: 10.1093/rheumatology/keh047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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75
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Bubbear J, Keen R. Clinical management and algorithms in osteoporosis. HOSPITAL MEDICINE (LONDON, ENGLAND : 1998) 2003; 64:512-6. [PMID: 14521065 DOI: 10.12968/hosp.2003.64.9.2241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
The aim of management in osteoporosis is to reduce the risk of fractures. Case-finding strategies are currently recommended to identify subjects at high risk of future fracture who will benefit most from therapy. This article reviews these approaches and discusses the current and future treatment options that are available for patients with osteoporosis.
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Abstract
Pigeons were placed in a long chamber equipped with one key and feeder at each end side and one key and houselight at the middle. To obtain food the birds had to choose one side key after a short signal and the other side key after a long signal. The signals consisted of the illumination of the center key and the houselight and were initiated by a peck at the center key. The chamber had sensitive floor panels that enabled us to measure the location of the bird during the signals. In Experiment 1, after the birds learned the discrimination we reversed the assignment of keys to signals. In Experiment 2, we examined performance on two pairs of discriminations holding the same ratio. In Experiment 3, after the pigeons learned to discriminate two signals, we changed the duration of the long signal. The results showed that (a) the birds' motion during the signal was highly stereotypical, i.e. the birds moved to the short side, waited a few seconds, and then departed to, and stayed on the long side; (b) this motion pattern predicted the results of generalization tests with novel durations; (c) the mean of the times of departure from the short side approached its steady state values quicker than the standard deviation and consequently superposition of behavioral measures became stronger with training; (d) only the duration of the short signal influenced significantly the moment the birds departed from the short side; finally (e) the times of arrival at and departure from the short side were positively correlated, but the times of arrival and residence at the short side were negatively correlated.
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Moss K, Keen R. Usefulness of bone densitometry in postmenopausal women with clinically diagnosed vertebral fractures. Ann Rheum Dis 2002; 61:667-8; author reply 668. [PMID: 12079924 PMCID: PMC1754151 DOI: 10.1136/ard.61.7.667-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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78
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Machado A, Keen R. Relative numerosity discrimination in the pigeon: further tests of the linear-exponential-ratio model. Behav Processes 2002; 57:131-148. [PMID: 11947994 DOI: 10.1016/s0376-6357(02)00010-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study tested a model of how animals discriminate the relative numerosity of stimuli in successive or sequential presentation tasks. In a discrete-trials procedure, pigeons were shown one light for nf times and then another for nl times. Next they received food for choosing the light that had occurred the least-number of times during the sample. At issue were (a) how performance varies with the interval between the two stimulus sets (the interblock interval) and the interval between the end of the sample and the beginning of the choice period (the retention interval); and (b) whether a simple mathematical model of the discrimination process could account for the data. The model assumed that the influence of a stimulus on choice increases linearly when the stimulus is presented, but decays exponentially when the stimulus is absent; choice probability is given by the ratio of the influence values of the two stimuli. The model also assumed that as the retention interval elapses there is an increasing probability that the ongoing discriminative process be disrupted and then the animal responds randomly. Results showed that increasing the interblock intervals reduced the probability of choosing the last stimulus of the sample as the least-frequent one. Increasing the retention interval reduced accuracy without inducing any stimulus bias. The model accounted well for the major trends in the data.
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79
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Hunter D, Major P, Arden N, Swaminathan R, Andrew T, MacGregor AJ, Keen R, Snieder H, Spector TD. A randomized controlled trial of vitamin D supplementation on preventing postmenopausal bone loss and modifying bone metabolism using identical twin pairs. J Bone Miner Res 2000; 15:2276-83. [PMID: 11092410 DOI: 10.1359/jbmr.2000.15.11.2276] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vitamin D supplementation, when given with calcium, has been shown to increase bone mineral density (BMD) and reduce the incidence of hip fracture in elderly subjects. Despite its widespread use, the benefits of vitamin D supplementation in younger women and as a single agent are less clear. We performed a randomized co-twin, placebo-controlled, double-blind trial over 2 years to measure the effect of vitamin D3 supplementation on bone density and bone metabolism in young postmenopausal women. Seventy-nine monozygotic (MZ) twin pairs (mean age, 58.7 years; range, 47-70 years) were recruited. For each twin pair, one was randomized to 800 IU cholecalciferol/day for 2 years and the other was randomized to placebo. BMD was measured at the spine and hip and heel ultrasound at baseline, 12, 18, and 24 months. Samples were collected at 0, 3, and 6 months to measure serum calcium, 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), osteocalcin, and urinary deoxypyridinoline (DPD). In total, 64 pairs completed the study. No differences in baseline characteristics were seen between the groups. At 6 months, the treatment group had an increase in serum vitamin D [mean +/- SEM intrapair difference, 14.1+/-2.4 microg/liter (p < 0.001)]. There were no significant differences in other serum measurements or bone markers at 3 months or 6 months. At 24 months, no significant treatment effect was seen on BMD or calcaneal ultrasound change within pairs. Subanalysis of treatment response by vitamin D receptor (VDR) genotype revealed no significant difference in effect on BMD variables with treatment. On the basis of these results, vitamin D supplementation, on its own, cannot be recommended routinely as an osteoporosis prevention for healthy postmenopausal women with normal vitamin D levels under the age of 70 years.
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Abstract
This study examined how pigeons discriminate the relative frequencies of events when the events occur serially. In a discrete-trials procedure, 6 pigeons were shown one light nf times and then another nl times. Next, they received food for choosing the light that had occurred the least number of times during the sample. At issue were (a) how the discrimination was related to two variables, the difference between the frequencies of the two lights, D = nf - nl, and the total number of lights in the sample, T = nf + nl; and (b) whether a simple mathematical model of the discrimination process could account for the data. In contrast with models that assume that pigeons count the stimulus lights, engage in mental arithmetic on numerons, or remember the number of stimuli, the present model assumed only that the influence of a sample stimulus on choice increases linearly when the stimulus is presented, but decays exponentially when the stimulus is absent. The results showed that, overall, the pigeons discriminated the relative frequencies well. Their accuracy always increased with the absolute value of the difference D and, for D > 0, it decreased with T. Performance also showed clear recency, primacy, and contextual effects. The model accounted well for the major trends in the data.
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81
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Spector TD, Snieder H, Keen R, Lewis C, MacGregor A. Interpreting the results of a segregation analysis of generalized radiographic osteoarthritis: comment on the article by Felson et al. ARTHRITIS AND RHEUMATISM 1999; 42:1068-70. [PMID: 10323471 DOI: 10.1002/1529-0131(199905)42:5<1068::aid-anr34>3.0.co;2-l] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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82
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Frazin LJ, Keen R, Astleford P, Blackburn DR, Yao JS. 980-86 Abdominal Aortic Ultrasound: A Comparison Between Transabdominal and Transgastric Approaches. J Am Coll Cardiol 1995. [DOI: 10.1016/0735-1097(95)92552-g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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83
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Wyns W, Schwaiger M, Huang SC, Buxton DB, Hansen H, Selin C, Keen R, Phelps ME, Schelbert HR. Effects of inhibition of fatty acid oxidation on myocardial kinetics of 11C-labeled palmitate. Circ Res 1989; 65:1787-97. [PMID: 2684448 DOI: 10.1161/01.res.65.6.1787] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of glucose and lactate infusion on palmitate oxidation were compared with the effect of 2-tetradecylglycidic acid (TDGA), an irreversible inhibitor of the carnitine acyltransferase I, in normoxic canine myocardium. The initial capillary transit retention fraction of [1-11C]palmitate and its fractional distribution between oxidation and esterification in myocardium were measured by the residue detection method after intracoronary tracer injection, as well as by effluent measurements of 11CO2, the end product of palmitate oxidation. TDGA reduced the initial capillary transit retention fraction (from 56 +/- 13% to 37 +/- 6%; p less than 0.001) and oxidation of palmitate (n = 19), as also evidenced by the decrease in the fraction of tracer released as 11CO2 from 28 +/- 5% to 6 +/- 3% (p less than 0.001). Infusion of carbohydrate (glucose or lactate; n = 6) reduced 11CO2 production from 30 +/- 7% to 7 +/- 4% (p less than 0.05) but did not alter the initial capillary transit retention fraction of tracer (59 +/- 5% vs. 56 +/- 10%; NS). The latter was due to increased esterification into neutral lipids (41 +/- 11% of injected palmitate after carbohydrate infusion versus 21 +/- 12% in control conditions), as measured from multiexponential curve fittings. When carbohydrates were given after inhibition of palmitate oxidation by TDGA (n = 7), the 11C tissue clearance kinetics were strikingly similar to those observed after carbohydrate infusion alone. Thus, enhanced metabolic trapping of [1-11C]palmitate in myocardium resulted in initial capillary transit retention fractions that were not different from control conditions (41 +/- 5% vs. 48 +/- 12%; NS) despite inhibition of oxidation. The results show that the intracellular metabolism of palmitate contributes to the control of its uptake by myocardium. The findings are consistent with inhibition of palmitate oxidation by carbohydrates occurring at the same site as TDGA.
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84
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Lufkin RB, Keen R, Rhodes M, Quinn J, Glenn W, Hanafee W. MRI simulator for instruction in pulse-sequence selection. AJR Am J Roentgenol 1986; 147:199-202. [PMID: 3521237 DOI: 10.2214/ajr.147.1.199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An ordinary desk-top microcomputer was programmed to simulate MR images for specified spin-echo pulse sequences. Model pixel maps of proton density and T1 and T2 relaxation times were made from published estimated values for regions of the human head, neck, and spine. Images were generated and displayed from the model maps and user-specified pulse-sequence parameters in less than 30 sec/image. Models for various pathologic conditions, including calcification, subacute hemorrhage, porencephaly, lipoma, and multiple sclerosis, were superimposed on the images of normal anatomy to create unknown cases. Simulated images can easily demonstrate the effect of pulse-sequence selection on the contrast of normal structures and pathologic conditions. Use of simulated images is an excellent technique for gaining experience in pulse-sequence selection. Low-cost microcomputers can provide adequate image detail and reasonable image display time of synthetic MR images for teaching purposes.
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Schwaiger M, Schelbert HR, Keen R, Vinten-Johansen J, Hansen H, Selin C, Barrio J, Huang SC, Phelps ME. Retention and clearance of C-11 palmitic acid in ischemic and reperfused canine myocardium. J Am Coll Cardiol 1985; 6:311-20. [PMID: 4019919 DOI: 10.1016/s0735-1097(85)80166-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Free fatty acids are the major energy source for cardiac muscle. Oxidation of fatty acid decreases or even ceases during ischemia. Its recovery after transient ischemia remains largely unexplored. Using intracoronary carbon-11 palmitic acid as a tracer of myocardial fatty acid metabolism in an open chest dog model, retention and clearance of tracer in myocardium were evaluated at control, during ischemia and after reperfusion following a 20 minute occlusion of the left anterior descending coronary artery. Myocardial C-11 time-activity curves were analyzed with biexponential curve-fitting routines yielding fractional distribution and clearance half-times of C-11 palmitic acid in myocardial tissue. In animals with permanent occlusion and intracoronary injection of C-11 palmitic acid distal to the occlusion site, the relative size and half-time of the early clearance curve component differed markedly from control values and did not change with ongoing ischemia. Conversely, in animals with only 20 minutes of coronary occlusion, the relative size of the early C-11 clearance phase was still significantly depressed at 20 and 90 minutes of reperfusion but returned to control level at 180 minutes. Tissue C-11 clearance half-times remained significantly prolonged throughout the reperfusion period. Regional function in reperfused myocardium monitored with ultrasonic crystals recovered slowly and was still less than control after 3 hours of reperfusion. The data indicate that after transient ischemia, myocardial fatty acid metabolism fails to recover immediately. Because the metabolic recovery occurs in parallel with recovery of regional function, C-11 palmitic acid in conjunction with positron tomography may be useful for studying regional fatty acid metabolism noninvasively after an ischemic injury, and may be helpful in identifying reversible tissue injury.
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Keen R, Filardo T, Colgan A. History and physical examination by oral and maxillofacial surgeons: the development of a physical assessment course. J Am Dent Assoc 1985; 110:64-6. [PMID: 3855923 DOI: 10.14219/jada.archive.1985.0286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Qualified oral surgeons may be granted hospital privileges to perform history and physical examinations on their patients as a result of a JCAH policy change, which became effective in January 1982. Oral surgeons must apply for and be granted this privilege from their affiliate hospitals and must demonstrate their qualifications. Various criteria can be used to assess qualification, including a review of the applicant's training in physical diagnosis in residency training, and participation in physical assessment continuing education programs. Review courses that feature hands-on practice are useful to oral surgeons interested in updating and refining their skills. Since the University of Illinois began offering a review course in 1981, 91 oral surgeons have completed the 2-day intensive review program. A follow-up survey of the participants indicates that the oral surgeons are applying for medical staff privileges. In a survey of 30 oral surgeons who participated in the course during 1982, 13 (43%) indicated that they had obtained the privilege to perform histories and physical examinations from their local hospitals.
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Eross J, Kreutzmann D, Jimenez M, Keen R, Rogers S, Cowell C, Vines R, Silink M. Colorimetric measurement of glycosylated protein in whole blood, red blood cells, plasma and dried blood. Ann Clin Biochem 1984; 21 ( Pt 6):477-83. [PMID: 6517486 DOI: 10.1177/000456328402100606] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A colorimetric method for the measurement of whole-blood glycosylation (WBG), glycosylated haemoglobin in red blood cells (GHb), glycosylated plasma protein (GPP) and dried-blood glycosylation (DBG) is described which is rapid, inexpensive and precise. GHb correlated well with HbA1 measured by cation-exchange chromatography and was also correlated with WBG, DBG and GPP. DBG, which showed good correlation with GHb, could be measured on several drops of blood dried on filter paper treated with glucose oxidase. Filter papers are posted to the laboratory prior to clinic visits, and by having the DBG result available more rational diabetic management is possible. For DBG, the intra- and inter-assay coefficient of variation at three levels is less than 6%. Reference values in non-diabetic children have been calculated and are compared with values obtained in 'good' clinical diabetic control and in 'fair' control. The filter-paper assay DBG method has a high degree of patient acceptance.
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88
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Hitchcock HB, Keen R, Kurta A. Survival Rates of Myotis leibii and Eptesicus fuscus in Southeastern Ontario. J Mammal 1984. [DOI: 10.2307/1381210] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Schelbert HR, Henze E, Keen R, Schon HR, Hansen H, Selin C, Huang SC, Barrio JR, Phelps ME. C-11 palmitate for the noninvasive evaluation of regional myocardial fatty acid metabolism with positron-computed tomography. IV. In vivo evaluation of acute demand-induced ischemia in dogs. Am Heart J 1983; 106:736-50. [PMID: 6604447 DOI: 10.1016/0002-8703(83)90096-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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90
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Schelbert HR, Henze E, Schon HR, Keen R, Hansen H, Selin C, Huang SC, Barrio JR, Phelps ME. C-11 palmitate for the noninvasive evaluation of regional myocardial fatty acid metabolism with positron computed tomography. III. In vivo demonstration of the effects of substrate availability on myocardial metabolism. Am Heart J 1983; 105:492-504. [PMID: 6600872 DOI: 10.1016/0002-8703(83)90368-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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91
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Keen R, Hitchcock HB. Survival and Longevity of the Little Brown Bat (Myotis lucifugus) in Southeastern Ontario. J Mammal 1980. [DOI: 10.2307/1379951] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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92
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Bland BH, Sinclair BR, Jorgenson RG, Keen R. A direct-drive, non-rotating version of Ranck's microdrive. Physiol Behav 1980; 24:395-7. [PMID: 7375557 DOI: 10.1016/0031-9384(80)90104-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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93
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Keen R, Parker DL. Determining expected duration of development under conditions of alternating temperatures. J Theor Biol 1979; 81:599-607. [PMID: 575398 DOI: 10.1016/0022-5193(79)90057-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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