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Brown E, Jr GAF, Shelton A, Johnson T, Chen C, Shaheen S, Holden TL, Dao VA, Bien JYE, King D, Vitzthum L, Kirilcuk N, Morris A, Kin C, Dawes A, Sheth V, Chang DT, Pollom E. A Technology-Informed Approach to Clinical Trial Equity. Int J Radiat Oncol Biol Phys 2023; 117:e8. [PMID: 37786184 DOI: 10.1016/j.ijrobp.2023.06.664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Despite efforts to increase participation of diverse communities in clinical trials, ethnic/racial minorities remain underrepresented. One such determinant may be lack of access to a comprehensive cancer center that conducts clinical research. Historically, our institution has had low accrual from rural regions further away from our cancer center, with Hispanic or Latino (HL) patients (pts) being especially underrepresented in our clinical research. In this study, we explored the impact of a clinical trial that allowed pts to receive chemotherapy (chemo) with their local oncologist. We hypothesize that allowing pts to receive chemo locally will lead to higher rates of enrollment from populations under-represented in clinical trials. MATERIALS/METHODS We conducted a study for pts with rectal cancer to undergo short-course radiation followed by 4 months of chemo with the option to pursue watch and wait if pts achieve a clinical complete response. Radiation was administered at our institution while pts could receive standard-of-care chemo closer to home with their local oncologist. For pts who received chemo locally, the research coordinator and co-investigators held video visits with the pts prior to each chemo infusion to review adverse events (AE), labs, and chemo dosing. We compared demographic data of pts on this trial with that of pts enrolled across all adult therapeutic oncologic clinical trials over the same time period at our institution. Distance to our institution was calculated based on pts' primary residence zip code. Protocol compliance with AE reporting for pts who received chemo locally was assessed by chart review. RESULTS Between May 2020 and January 2023, 24/35 enrolled pts completed both radiation and chemo on trial. 13/24 pts (54%) received chemo locally. Of the 24 pts, 16 were White (67%), 7 Asian (29%), 1 Native Hawaiian/ Pacific Islander (4%). Of all enrolled patients, 4 were HL (16.7%), compared to our institutional average of 16.5%. All enrolled HL pts received their chemo locally. The average distance traveled by non-HL pts from their home to our institution was 87.7 miles (range 5.1 - 308). In contrast, HL pts traveled an average of 147.8 miles (range 110 - 249), 68% further than their non-HL counterparts. There was 100% compliance with AE reporting among those pts who received their chemo locally. CONCLUSION Although the percentage of HL participation in our study was consistent with our institutional average, all HL pts enrolled on the trial received treatment locally and lived substantially further from our institution than non-HL. By allowing pts to receive this part of treatment locally, we provided pts who live further away an opportunity to engage in clinical research without the associated financial and time toxicities related with traveling for treatment. By decentralizing clinical trials and leveraging telemedicine, we can promote the participation of under-represented groups in clinical trials.
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Affiliation(s)
- E Brown
- Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA
| | - G A Fisher Jr
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - A Shelton
- Department of Surgery, Stanford University School of Medicine, Palo Alto, CA
| | - T Johnson
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - C Chen
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - S Shaheen
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - T L Holden
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - V A Dao
- Department of Medicine, Stanford University School of Medicine, Palo Alto, CA
| | - J Y E Bien
- Kaiser Permanente Santa Clara Medical Center, Santa Clara, CA
| | - D King
- Department of Medical Oncology/Hematology, Northwell Health Cancer Institute, New Hyde Park, NY
| | - L Vitzthum
- Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA
| | - N Kirilcuk
- Department of Surgery, Stanford University School of Medicine, Palo Alto, CA
| | - A Morris
- Department of Surgery, Stanford University School of Medicine, Palo Alto, CA
| | - C Kin
- Department of Surgery, Stanford University School of Medicine, Palo Alto, CA
| | - A Dawes
- Department of Surgery, Stanford University School of Medicine, Palo Alto, CA
| | - V Sheth
- Department of Radiology, Stanford University School of Medicine, Palo Alto, CA
| | - D T Chang
- Department of Radiation Oncology, Michigan Medicine, Ann Arbor, MI
| | - E Pollom
- Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA
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Rath A, Wong M, Pannuti CM, Hesarghatta Ramamurthy P, Fernandes B, Shelton A, Muttalib KA. Cross-cultural adaptation and validation of Malay version of Rapid Estimate of Adult Literacy in Dentistry (MREALD-30) among Orang Asli population in Malaysia. BMC Oral Health 2021; 21:519. [PMID: 34641831 PMCID: PMC8513292 DOI: 10.1186/s12903-021-01866-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/28/2021] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The aim of this study was to adapt, translate and validate the Rapid Estimate of Adult Literacy in Dentistry (MREALD-30) instrument for the Orang Asli population in Malaysia. METHODS After translation and cross-cultural adaptation, interviews were conducted with 326 participants of the Temuan tribe from village Kampung Tering in Johol, Negeri Sembilan, Malaysia. The instrument's validity was assessed using the scores of MREALD-30, which were compared based on occupation, monthly household income, educational attainment, general literacy, use of dental services, and three dental outcomes. A questionnaire containing socio-behavioral information and validated Malay Oral Health Impact Profile (M-OHIP-14) was also administered. The reliability of the MREALD-30 was assessed by re-administering it to 30 subjects after two weeks. Its correlations evaluated convergent and discriminative validity of MREALD-30 with the level of education and dental visiting habits, monthly household income, respectively. Predictive validity was assessed with M-OHIP-14, while construct validity was evaluated by exploratory factor analysis using the Rasch model. RESULTS The internal consistency of the MREALD-30 measured by Cronbach's alpha was 0.89. The test-retest reliability was excellent (ICC 0.95, k = 0.85). MREALD-30 exhibited good construct validity. Rasch analysis showed two factors, and infit mean-square statistics for MREALD-30 were all within the desired range of 0.50-2.0. The discriminant validity and predictive validity were statistically significant (p < 0.05). CONCLUSIONS MREALD-30 showed very strong reliability, good construct, discriminant, and predictive validity, but poor convergent validity. Overall, it showed good psychometric properties and can be used in these community settings.
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Affiliation(s)
- Avita Rath
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia.
| | - Melissa Wong
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
| | | | | | - Bennete Fernandes
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
| | | | - Khairiyah Abdul Muttalib
- Faculty of Dentistry, SEGi University, No. 9 Jalan Teknologi PJU5, 47810, Kota Damansara, Selangor, Malaysia
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Cheng K, Qureshi M, Dyer M, Bloch B, Gignac G, Katz M, Shelton A, Cruz R, Pottier E, Hirsch A. Patient-Reported QOL Outcomes of Hypofractionated Stereotactic Body Radiation Therapy Boost for the Treatment of Localized, Non-Metastatic, High-Risk Prostate Cancer: Updated Results of a Phase II Trial. Int J Radiat Oncol Biol Phys 2020. [DOI: 10.1016/j.ijrobp.2020.07.533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hanna BR, Saylor HE, Schuster JG, Shelton A, Hickner RC, Chow G, Ormsbee MJ. CHARACTERIZING PERFORMANCE IN ELITE TRACK AND FIELD SPRINTERS IN RELATION TO THE ACUTE:CHRONIC WORKLOAD RATIO. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675948.23003.8e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hulsbergen M, Topaz S, Kumar A, Bishop N, Shelton A, Granger S, Chiang B, DE Boer L, Luikenaar R, Mohammed S, Kolff W. Elastomeric Valves, a New Design. Int J Artif Organs 2018. [DOI: 10.1177/039139889501800405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The convex bileaflet valve replaces the flat biflap inflow valve designed by Long Sheng Yu and the tricusp semilunair outflow valve. One reason is easier manufacturing. Convex bileaflet valves are developed for the 11, 20, 40, 70 and 140cc ventricles. Testing included curves (Cardiac Output versus Venous Pressure, Cardiac Output versus Heart rate), flow visualization studies, paint and bloodbag studies. The curves and flow visualization were done by connecting ventricles to one of our standard mock circulations. Paint and bloodbag studies were done by connecting the hearts to a bloodbag, but the bag was filled with water for the paint studies. The curves show high cardiac output, even with pumping at high heart rates (150 BPM+). The flow visualization shows a good stream through the sinus Valsalvae. No stagnating flow is visible. The bloodbag studies which provoke thrombosis show it on the edges of the heart valves, and little in the groove between the valve and the sinus Valsalvae. Heparninzation prevents the thrombosis. Results of our tests were good. The convex bileaflet valve seems to have good future.
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Affiliation(s)
- M.H. Hulsbergen
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - S. Topaz
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - A. Kumar
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - N.D. Bishop
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - A. Shelton
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - S. Granger
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - B.Y. Chiang
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - L. DE Boer
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - R.A. Luikenaar
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - S.F. Mohammed
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
| | - W.J. Kolff
- Kolff's Laboratory, University of Utah, Salt Lake City - USA
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Gill T, McGloin J, Charpentier P, Araujo K, Skokos E, Latham N, Shelton A, Lu C. STRIDE: SCREENING AND RECRUITING OLDER PATIENTS AT RISK FOR SERIOUS FALL INJURIES. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.3657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- T.M. Gill
- Yale University, New Haven, Connecticut,
| | - J. McGloin
- Yale University, New Haven, Connecticut,
| | | | | | - E. Skokos
- Yale University, New Haven, Connecticut,
| | - N. Latham
- Brigham and Women’s Hospital, Boston, Boston, Massachusetts
| | - A. Shelton
- Yale University, New Haven, Connecticut,
| | - C. Lu
- Yale University, New Haven, Connecticut,
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Hosey K, Waldron J, Shelton A, Mburu J, Farquhar C. Teaching Global Health Nursing: The Process of Integrating Nursing
Training into the Clinical Education Partnership Initiative. Ann Glob Health 2017. [DOI: 10.1016/j.aogh.2017.03.097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Story DA, Shelton A, Jones D, Heland M, Belomo R. Audit of co-management and critical care outreach for high risk postoperative patients (The POST audit). Anaesth Intensive Care 2014; 41:793-8. [PMID: 24180722 DOI: 10.1177/0310057x1304100616] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Co-management and critical care outreach for high risk surgical patients have been proposed to decrease postoperative complications and mortality. We proposed that a clinical project with postoperative comanagement and critical care outreach, the Post Operative Surveillance Team: (POST), would be associated with decreased hospital length of stay. We conducted a retrospective before (control group) and after (POST group) audit of this hospital program. POST was staffed for four months in 2010 by two intensive care nurses and two senior registrars who conducted daily ward rounds for the first five postoperative days on high risk patients undergoing inpatient general or urological surgery. The primary endpoint was length of hospital stay and secondary endpoints were Medical Emergency Team (MET) calls, cardiac arrests and in-hospital mortality. There were 194 patients in the POST group and 1,185 in the control group. The length of stay in the POST group, median nine days (Inter-quartile range [IQR]: 5 to 17 days), was longer than the control group, median seven days (IQR: 4 to 13 days): difference two days longer (95.0% confidence interval [95.0% CI]: 1 to 3 days longer, P <0.001). There were no important differences in the proportion of patients having MET calls (16.0% POST versus. 13% control (P=0.25)) or mortality (2.1% POST versus 2.8% Control (P=0.82)). Our audit found that the POST service was not associated with reduced length of stay. Models of co-management, different to POST, or with different performance metrics, could be tested.
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Affiliation(s)
- D A Story
- Division of Surgery and Departments of Intensive Care and Anaesthesia, Austin Health; and Anaesthesia, Perioperative and Pain Medicine Unit, Melbourne Medical School, University of Melbourne, Melbourne, Victoria
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Affiliation(s)
- Hani Abudiak
- Senior Dental Officer, Bradford and Airedale PCT, 99 Horton Park Avenue, Bradford
| | - A Shelton
- FTTA in Orthodontics, Seacroft Hospital and Leeds Dental Institute, Clarendon Way, Leeds, LS2 9LU
| | - RJ Spencer
- Consultant Orthodontist, Orthodontic Department, Pinderfields General Hospital, Wakefield
| | - L Burns
- Dental Student at Leeds Dental Institute, Worsley Building, Clarendon Way, Leeds
| | - SJ Littlewood
- Consultant Orthodontist, Orthodontic Department, St Luke's Hospital, Little Horton Lane, Bradford, BD5 0NA, UK
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Clements-Stephens A, Shelton A. Spatial organization and configural processing strategies: From perception to memory. J Vis 2011. [DOI: 10.1167/11.11.1086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Seldin DC, Andrea N, Berenbaum I, Berk JL, Connors L, Dember LM, Doros G, Fennessey S, Finn K, Girnius S, Lerner A, Libbey C, Meier-Ewert HK, O'Connell R, O'Hara C, Quillen K, Ruberg FL, Sam F, Segal A, Shelton A, Skinner M, Sloan JM, Wiesman JF, Sanchorawala V. High-dose melphalan and autologous stem cell transplantation for AL amyloidosis: recent trends in treatment-related mortality and 1-year survival at a single institution. Amyloid 2011; 18 Suppl 1:127-9. [PMID: 21838459 PMCID: PMC5601311 DOI: 10.3109/13506129.2011.574354047] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Treatment with high-dose melphalan chemotherapy supported by hematopoietic rescue with autologous stem cells produces high rates of hematologic responses and improvement in survival and organ function for patients with AL amyloidosis. Ongoing clinical trials explore pre-transplant induction regimens, post-transplant consolidation or maintenance approaches, and compare transplant to non-transplant regimens. To put these studies into context, we reviewed our recent experience with transplant for AL amyloidosis in the Amyloid Treatment and Research Program at Boston Medical Center and Boston University School of Medicine. Over the past 10 years, there was a steady reduction in rates of treatment-related mortality and improvement in 1-year survival, now approximately 5% and 90%, respectively, based upon an intention-to-treat analysis. Median overall survival of patients treated with this approach at our center exceeds 7.5 years.
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Affiliation(s)
- D C Seldin
- Clinical Trials Office, Boston University School of Medicine and Boston Medical Center, Boston, MA 02118, USA
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Bazan J, Hara W, Kunz P, Fisher G, Ford J, Welton M, Koong A, Shelton A, Goodman K, Chang D. Intensity Modulated Radiation Therapy vs. Conventional Radiation Therapy for Squamous Cell Carcinoma of the Anal Canal. Int J Radiat Oncol Biol Phys 2010. [DOI: 10.1016/j.ijrobp.2010.07.714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Walsh M, Gmeindl L, Flombaum J, Shelton A. Spatial working memory is limited by fixed resolution representations of location. J Vis 2010. [DOI: 10.1167/10.7.751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Chennupati SK, Kamaya A, Fisher GA, Ford JM, Kunz P, Itakura H, Welton ML, Shelton A, Van Dam J, Koong AC, Chang DT. Pathological response after chemoradiation for T3 rectal cancer. Colorectal Dis 2010; 12:e24-30. [PMID: 19614668 DOI: 10.1111/j.1463-1318.2009.02013.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE The aim of this study was to investigate the effect of preoperative chemoradiotherapy (CRT) on nodal disease in locally advanced rectal adenocarcinoma. METHOD Thirty-two patients staged uT3N0 and 27 patients staged uT3N1 rectal adenocarcinoma who underwent pre-CRT staging using endoscopic ultrasound or rectal protocol CT were included. The median radiation dose was 50.4 Gy (range: 45-50.4 Gy) at 1.8 Gy per fraction and all patients received concurrent 5-FU or capecitabine-based chemotherapy. Low anterior resection or abdomino-perineal resection occurred at a median of 46 days (range: 27-112 days) after CRT. RESULTS Eleven of 32 uT3N0 patients (34.4%) and 13 of 26 uT3N1 patients (50.0%) had ypN+ (P = 0.29). For patients with uT3N0, 10 of 20 (50.0%) with ypT2-3 and 1 of 12 (8.3%) with ypT0-1 were ypN+ (P = 0.02). For patients with uT3N1, 12 of 20 (60.0%) with ypT2-3 and 1 of 6 (16.7%) with ypT0-1 were ypN+ (P = 0.16). Overall, the ypN+ rate was 11.1% in the ypT0-yT1 group compared with 55.0% in the ypT2-yT3 group (P = 003). Among patients with uT3N0 disease, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 7.1%vs 55.6% (P = 0.01) respectively. Among patients with uT3N1 disease, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 54.5%vs 46.7%, (P = 0.99) respectively. Overall, the ypN+ rate in patients who had surgery > 46 days vs<or= 46 days was 28.0%vs 51.5% (P = 0.11). CONCLUSIONS The risk of residual nodal disease after CRT is significant. Primary tumour response is associated with nodal response.
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Affiliation(s)
- S K Chennupati
- Department of Radiation Oncology, Stanford University Medical Center, Stanford, CA, USA
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Cabebe EC, Kuo T, Koong A, Welton M, Shelton A, Kunz PL, Ford JM, Sikic BI, Kaiser HL, Rogers J, Fisher GA. Phase I trial of preoperative cetuximab in combination with oxaliplatin, capecitabine, and radiation therapy for locally advanced rectal cancer. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.15019] [Citation(s) in RCA: 10] [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: 11/20/2022] Open
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Abstract
Combined tension-torsion tests have been performed at constant stress ratios on En 25 steel, previously annealed and then subjected to a pre-stress in either tension or torsion.The post-yield behaviour showed marked room-temperature creep and, in general, both the axial- and the shear-strain components could be expressed by the logarithmic creep equation. The direction of the incremental strain-ratio vector was initially markedly different from that shown in the previous tests on annealed En 25 steel, but rotated towards that direction with increased stress. The yield locus subsequent to each pre-stress was established by fulfilling two requirements: that it must pass through the stress space normal to all the plastic-strain-increment vectors it encounters; that each yield stress should be an extrapolation from the curves of creep coefficient plotted against stress and stress plotted against ‘long time’ strain.The results show that a pre-stress hardens the material over that half of biaxial stress space bisected by the pre-stress axis and hardens it less or even softens it in the reverse half of that space. The cross-effect of a tensile pre-stress is greater than that of a torsion pre-stress and increasing the degree of pre-stress has a gradually reducing cross-effect.
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Affiliation(s)
- J Rogan
- Imperial College of Science and Technology, London
| | - A Shelton
- Imperial College of Science and Technology, London
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Abstract
Constant-stress-ratio tests under combined tension-torsion have been performed on annealed En 25 and En 24 steels. The sharp yield behaviour of these materials enabled the initial yield locus to be clearly defined and this was close to that predicted by the Tresca criterion. Post-yield behaviour showed marked room-temperature creep of the logarithmic form ∊ = a ln t+ c, by both the axial- and shear-strain components. The strain-rate ratios and the strain ratios were normal to the yield locus and remained so for increasing stress.The equivalent-plastic-work hypothesis did not produce satisfactory correlation of the combined-stress results and empirical equivalence of the strains was established by introducing a factor to account for the influence of combined stresses upon the magnitude of the resulting strains. This empirical equivalence also provided good correlation of the creep-strain rates and these results finally led to the complete correlation of the stress-strain-time behaviour of these materials at room temperature.
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Affiliation(s)
- J Rogan
- Imperial College of Science and Technology, London
| | - A Shelton
- Imperial College of Science and Technology, London
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Abstract
Tests under combinations of tension, torsion and internal pressure have been performed at constant stress ratio on En24 steel, previously annealed, and then subjected to a pre-stress in either axial or circumferential tension or torsion. Post-yield behaviour showed marked room-temperature creep by all strain components in the logarithmic form ε = a In t + c. The initial direction of the incremental plastic strain-ratio vector was markedly different from isotropic behaviour and remained constant in direction with time. Increased loading resulted in a progressive rotation towards the isotropic direction. Anisotropic yield loci were established from the normality rule and from the backward extrapolation of curves of creep coefficient versus stress and stress versus ‘long-time’ strain. The yield locus was translated to the pre-stress point and this local work-hardening was accompanied by softening in both the transverse and reverse directions, i.e. the cross-effect and Bauschinger effect respectively. Yield loci in planes not containing the pre-stress axis showed softening in all directions and under axial tension-internal pressure the cross-effect caused a rotation of the locus. All yield loci were smooth and continuous. Yield criteria derived from the theories of Edelman and Drucker and also Williams and Svensson were in good agreement with experiment over the whole locus. Hill's theory was thought to be more appropriate to material behaviour following large deformations.
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Affiliation(s)
- S. N. Shahabi
- Professor of Engineering, University of Tabriz, Iran. Formerly Research Student, Department of Mechanical Engineering. Imperial College, London
| | - A. Shelton
- Lecturer, Department of Mechanical Engineering, Imperial College, London. Member of the Institution
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Tillman G, Fisher G, Cho C, Ford J, Mehta V, Welton M, Shelton A, Bastidas J, Young H, Koong A. The stanford experience with preoperative chemoradiation using CPT-11 and 5-FU in locally advanced rectal cancer: Toxicities and outcomes. Int J Radiat Oncol Biol Phys 2004. [DOI: 10.1016/j.ijrobp.2004.07.304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bayston R, Andrews M, Rigg K, Shelton A. Recurrent infection and catheter loss in patients on continuous ambulatory peritoneal dialysis. Perit Dial Int 1999; 19:550-5. [PMID: 10641776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
OBJECTIVE To elucidate the factors leading to catheter loss from recurrent infection in patients on continuous ambulatory peritoneal dialysis (CAPD). DESIGN All catheters removed from patients were prospectively examined for infection. SETTING CAPD unit in large tertiary-care general hospital. PATIENTS Sixty-five consecutive patients undergoing catheter removal for whatever cause; 20 catheters rejected because of desiccation or contamination in transit. INTERVENTIONS None. MAIN OUTCOME MEASURES Micro-organisms linked to catheter removal; their locations on removed catheters. RESULTS Of 45 catheters removed between January 1994 and August 1995, 26 were infected: 13/26 infections were caused by Staphylococcus aureus and 7/26 by Pseudomonas aeruginosa. In only one case was S. epidermidis associated with catheter removal. The most striking finding was that the inner cuff harbored large numbers of the infecting organisms, even when antibiotics had eradicated them from the peritoneal cavity and exit site, where present, and the catheter lumen. CONCLUSION The importance of S. aureus and Ps. aeruginosa rather than S. epidermidis in catheter loss due to relapsing infection is confirmed. Persistence of the causative organisms in the inner cuff is a likely explanation for relapse after treatment, and might be due to the predominantly intraperitoneal administration of antibiotics. A clinical trial of the effect on catheter retention of empirical use of systemic or oral agents that give high tissue levels and are active against intracellular micro-organisms, along with recommended intraperitoneal regimens, is indicated.
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Affiliation(s)
- R Bayston
- Division of Microbiology, University of Nottingham, United Kingdom
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Cunningham R, Gurnell M, Bayston R, Cockayne A, Shelton A. Teicoplanin resistance in Staphylococcus haemolyticus, developing during treatment. J Antimicrob Chemother 1997; 39:438-9. [PMID: 9096201 DOI: 10.1093/jac/39.3.438] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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Hulsbergen MH, Topaz S, Kumar A, Bishop ND, Shelton A, Granger S, Chiang BY, De Boer L, Luikenaar RA, Mohammed SF. Elastomeric valves, a new design. Int J Artif Organs 1995; 18:203-9. [PMID: 8530200] [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: 01/31/2023]
Abstract
The convex bileaflet valve replaces the flat biflap inflow valve designed by Long Sheng Yu and the tricusp semilunair outflow valve. One reason is easier manufacturing. Convex bileaflet valves are developed for the 11, 20, 40, 70 and 140cc ventricles. Testing included curves (Cardiac Output versus Venous Pressure, Cardiac Output versus Heart rate), flow visualization studies, paint and bloodbag studies. The curves and flow visualization were done by connecting ventricles to one of our standard mock circulations. Paint and bloodbag studies were done by connecting the hearts to a bloodbag, but the bag was filled with water for the paint studies. The curves show high cardiac output, even with pumping at high heart rates (150 BPM+). The flow visualization shows a good stream through the sinus Valsalvae. No stagnating flow is visible. The bloodbag studies which provoke thrombosis show it on the edges of the heart valves, and little in the groove between the valve and the sinus Valsalvae. Heparninzation prevents the thrombosis. Results of our tests were good. The convex bileaflet valve seems to have good future.
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Affiliation(s)
- M H Hulsbergen
- Kolff's Laboratory, University of Utah, Salt Lake City, USA
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van Loon J, Wilde JC, Topaz SR, Bishop ND, Shelton A, Marten C, Pantalos G, Kolff WJ, Thomas G, Nakajima H. The development of a valveless cardiac assist device attached to the ventricular apex. ASAIO J 1994; 40:171-5. [PMID: 8003754] [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: 01/28/2023] Open
Abstract
Konstantinov et al, in October, 1991, published a novel way to bridge a patient for heart transplantation. They proposed to cut off both ventricles high under the atrioventricular groove, leaving the atria, aorta, and pulmonary artery and their valves intact and to attach pneumatically driven, valveless pulsating pouches to assist the heart until a donor could be found. The removal of the ventricles just below the atrioventricular groove is called the "high cut"; it, however, destroys the chordae tendineae rendering the mitral and tricuspid valves insufficient. These have to be replaced by tissue inflow valves. We chose to cut off the ventricles at a lower level (the "low cut") to leave the papillary muscles on both sides intact, thereby saving the integrity of the mitral and tricuspid valves. Pulsating pouches were made to fit the heart at this lower level. They can be easily connected to the remaining heart after a specially disigned cuff has been sutured over the ventricular stumps. The pouches were pumped during the systole of the natural heart, but the myocardium may have to be electrically stimulated during systole to prevent undue distension. If the turgor is too weak to prevent distension, a sleeve over the ventricles is provided. To find the best location for these pouches, human cadaver implantations were done and the pre peritoneal cavity was found to be the most suitable. In vitro testing to determine how much flow could be pumped was done by attaching the pouches to fresh pig hearts and connecting them to a double sided mock circulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J van Loon
- University of Utah, Salt Lake City 84112
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Abstract
The action of ciprofloxacin and norfloxacin on two strains of Escherichia coli was studied by diverse methods including electronmicroscopy, viable counting and continuous turbidimetric monitoring. During the first few hours of exposure to inhibitory concentrations of the drugs, the opacity of bacterial cultures continued to increase for a period that was inversely proportional to the drug concentration. This change corresponded to the appearance of filamentous bacteria, swollen forms and some lysis. There was subsequently a gradual drop in opacity during which extensive lysis occurred. As judged by viable counts of bacteria washed free of drug, cell death occurred within 30 min of first exposure to the drugs and continued over a 3-h period. Ultrastructure studies demonstrated that lysis was preceded by the formation of vacuoles, predominantly at the poles of the cells. At these sites, breaks in the cell walls eventually occurred, resulting in extrusion of the cytoplasmic contents.
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Kaliner M, Dyer J, Merlin S, Shelton A, Greenhill A, Treadwell G, McKenna W, Lieberman P. Increased urine histamine and contrast media reactions. Invest Radiol 1984; 19:116-8. [PMID: 6533100 DOI: 10.1097/00004424-198403000-00007] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Urine samples were collected from 200 subjects undergoing intravenous pyelography. The urine histamine levels were compared with those of 132 normal control subjects, 11 subjects with systemic mastocytosis, six subjects with idiopathic anaphylaxis, and ten subjects experiencing mild anaphylactic reactions during allergy immunotherapy. Compared with normal controls, as a group, all subjects receiving intravenous contrast media had increased urine histamine (P less than 0.05 by Student's t-test) while those subjects experiencing adverse reactions had considerably larger increases. The urine histamine levels in the subjects experiencing systemic reactions were in the same range as those observed in patients having mild anaphylactic reactions to immunotherapy and somewhat lower than those found in idiopathic anaphylaxis or systemic mastocytosis. These data suggest that some histamine release accompanies infusions of contrast media in all subjects and that larger amounts of histamine release are associated with adverse reactions.
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