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Homenauth E, Ghiasi M, Feldman L, Arrouf N, Mallya S, Lacombe J, Pichika SC, Zhao K, Aibibula W, Krishnan R, Kajeguka D, Kaaya R, Protopopoff N, Mosha F, Desrochers R, Watts A, Kulkarni M, Saravu K, Nair S, Mukhopadhyay C, George LS, Pai M, Jiang H, Brown P, Blais L, Lefebvre G, Samoilenko M, Kulkarni M, Jolly A, Roy-Gagnon MH, Sander B, Gauvreau CL, Memon S, Popadiuk C, Flanagan WM, Nadeau C, Coldman AJ, Wolfson MC, Miller AB, Acar E, Cox J, Hamelin AM, McLinden T, Klein MB, Brassard P, Chong M, Martin J. The Canadian Society for Epidemiology and Biostatistics 2016 National Student Conference001INVESTIGATING ECOLOGICAL DETERMINANTS OF MALARIA VECTOR DISTRIBUTION IN RURAL TANZANIA “A MULTI-SCALAR INVESTIGATION”002PREVALENCE AND RISK FACTORS OF TUBERCULOSIS INFECTION AMONG HEALTHCARE TRAINEES IN SOUTH INDIA003SPATIAL MODELLING OF LUNG AND THYROID CANCERS IN UNITED STATES COUNTIES004A MEDIATION ANALYSIS TO ASSESS THE IMPACT OF INHALED CORTICOSTEROIDS (ICSS) DURING PREGNANCY ON BIRTHWEIGHT005MODELLING HUMAN RISK OF WEST NILE VIRUS IN ONTARIO, 2002-2013: INCORPORATING SURVEILLANCE AND ENVIRONMENTAL DATA006EXPLORING THE HEALTH OUTCOMES OF VARIOUS PAN-CANADIAN CERVICAL CANCER SCREENING PROGRAMS USING MICROSIMULATION MODELING007INTEGRATIVE ANALYSIS OF MICRORNA AND GENE EXPRESSION DATA USING SPARSE CANONICAL CORRELATION ANALYSIS008CONDITIONAL DEPENDENCE MODELS UNDER COVARIATE MEASUREMENT ERROR009ASSOCIATION BETWEEN FOOD INSECURITY AND HIV VIRAL SUPPRESSION: A SYSTEMATIC REVIEW AND META-ANALYSIS010ANTIBIOTICS VERSUS APPENDECTOMY FOR UNCOMPLICATED APPENDICITIS: A GLOBAL HEALTH PERSPECTIVE. Am J Epidemiol 2016. [DOI: 10.1093/aje/kww058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Chong M, Cartledge J, Waters LJ. Significant benefit of a targeted HIV testing module on medical students' knowledge and confidence. Int J STD AIDS 2015; 27:1326-1329. [PMID: 26568252 DOI: 10.1177/0956462415618111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/08/2015] [Accepted: 10/28/2015] [Indexed: 11/15/2022]
Abstract
The objective was to evaluate the efficacy of a HIV targeted-testing teaching session in improving knowledge and confidence at a London medical school. A survey assessing knowledge of HIV testing guidelines, confidence to offer testing and outcomes of targeted-testing teaching was developed and distributed to fifth year medical students. Results were compared for students who had completed GU/HIV modules (GU+) and those who had not (GU-) and chi-squared testing was performed; 100 and 119 questionnaires were returned by GU+ and GU- students (response rate of 92.6% and 97.5%), respectively. For the three knowledge-based questions, GU+ students were significantly more likely to provide correct answers for two (p < 0.001). Similarly, they were significantly more likely to feel confident in offering an HIV test (p < 0.001). After targeted-testing teaching 92%, 98% and 62% felt more confident about when to test, how to discuss testing and more knowledgeable about testing, respectively. Most students were happy to offer HIV testing in different medical settings; significantly fewer reported this for an acute admissions unit compared with antenatal clinic (79% vs 96%). Students who had received targeted-testing teaching demonstrated better knowledge and confidence about HIV testing. We hope this study raises awareness of the need to include HIV testing teaching in medical school curricula.
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Chong M, Callini E, Borgschulte A, Züttel A, Jensen CM. Dehydrogenation studies of the bimetallic borohydrides. RSC Adv 2014. [DOI: 10.1039/c4ra10352a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Lliteras ER, Chong M, Andries S, Merckx E, Jorssen EPA, Leroy JLMR, Bols PEJ. 84 THE EFFECT OF β-MERCAPTOETHANOL ON CLEAVAGE RATES, DEVELOPMENTAL COMPETENCE AND QUALITY OF IN VITRO PRODUCED BOVINE EMBRYOS. Reprod Fertil Dev 2014. [DOI: 10.1071/rdv26n1ab84] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The production of excessive levels of reactive oxygen species can be a major problem during in vitro embryo culture. Although studies have shown that supplementation with exogenous antioxidants can improve embryo quality, the results are controversial among researchers. In this study, we examined the effects of different concentrations of β-mercaptoethanol (β-ME) added to the culture media, on cleavage rates, the quality and developmental competence of in vitro-produced bovine embryos. The embryos were produced in vitro as described previously (Van Hoeck et al., 2013). Briefly, in total, 753 grade I cumulus–oocyte complexes (COC) from 2- to 6-mm-diameter follicles were matured in groups of 50 in 500 μL of TCM with 20 ng mL–1 EGF for 24 h, fertilized in groups of 100 in 500 μL of fertilization medium for 20 h (5% CO2, 38.5°C). Presumptive zygotes were denuded and randomly assigned to 4 treatments with different concentrations of β-ME: 0 μM (control), 50 μM, 100 μM, and 150 μM. They were cultured in groups of ±25 in 50 μL of SOF supplemented with ITS (10 μg mL–1 insulin; 5.5 μg mL–1 transferrin; 6.7 ng mL–1 selenium) and 2% BSA and covered with mineral oil (5% O2, 5% CO2, 38.5°C). At 48 h post-insemination (p.i.), cleavage rate was evaluated and expressed as the number of cleaved embryos on total number of oocytes. At Day 7 p.i., blastocyst rate was determined (number of blastocysts on total number of oocytes), blastocysts were fixed in 4% paraformaldehyde, and total cell number was determined by DAPI staining. Data were analysed by ANOVA and post hoc test. Comparable cleavage rates were obtained in treated groups: control (80.8%), 50 μM (77.7%), 100 μM (77.9%), and 150 μM (73.6%; P > 0.05). Also, no significant effect of treatment could be found on blastocyst rates: control (36%), 50 μM (36.5%), 100 μM (38.4%), and 150 μM (30.4%). The total cell number per blastocyst increased significantly (P < 0.05) using 100 μM of β-ME compared with the controls (158.0 ± 24.3 v. 123.2 ± 9.72, respectively). These results suggest that the inclusion of 100 μM β-ME during in vitro embryo culture could be used for production of high quality bovine blastocysts.
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Zhao H, Watts HR, Chong M, Huang H, Tralau-Stewart C, Maxwell PH, Maze M, George AJT, Ma D. Xenon treatment protects against cold ischemia associated delayed graft function and prolongs graft survival in rats. Am J Transplant 2013; 13:2006-18. [PMID: 23710625 PMCID: PMC3884761 DOI: 10.1111/ajt.12293] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/18/2013] [Accepted: 04/04/2013] [Indexed: 01/25/2023]
Abstract
Prolonged hypothermic storage causes ischemia-reperfusion injury (IRI) in the renal graft, which is considered to contribute to the occurrence of the delayed graft function (DGF) and chronic graft failure. Strategies are required to protect the graft and to prolong renal graft survival. We demonstrated that xenon exposure to human proximal tubular cells (HK-2) led to activation of range of protective proteins. Xenon treatment prior to or after hypothermia-hypoxia challenge stabilized the HK-2 cellular structure, diminished cytoplasmic translocation of high-mobility group box (HMGB) 1 and suppressed NF-κB activation. In the syngeneic Lewis-to-Lewis rat model of kidney transplantation, xenon exposure to donors before graft retrieval or to recipients after engraftment decreased caspase-3 expression, localized HMGB-1 within nuclei and prevented TLR-4/NF-κB activation in tubular cells; serum pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were reduced and renal function was preserved. Xenon treatment of graft donors or of recipients prolonged renal graft survival following IRI in both Lewis-to-Lewis isografts and Fischer-to-Lewis allografts. Xenon induced cell survival or graft functional recovery was abolished by HIF-1α siRNA. Our data suggest that xenon treatment attenuates DGF and enhances graft survival. This approach could be translated into clinical practice leading to a considerable improvement in long-term graft survival.
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Foong HBB, Chong M, Taylor EM, Carlson JA, Petrella T. Blastic plasmacytoid dendritic cell neoplasm in an elderly woman. THE MEDICAL JOURNAL OF MALAYSIA 2013; 68:161-163. [PMID: 23629565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Blastic plasmacytoid dendritic cell neoplasm (a.k.a. NK cell lymphoma, CD4+CD56+ haematodermic neoplasm) is a rare aggressive tumour that arises from plasmacytoid dendritic cell precursors. We report the first case from Malaysia of a 79-year-old Chinese woman who presented with purpuric plaques and nodules produced by pleomorphic CD4+, CD56+, CD68+, CD123+ and CD303+, but CD2APmononuclear cell infiltrates. Leukemic dissemination occurred and she succumbed to disease without treatment 4 weeks after diagnosis and 9 months after onset of cutaneous disease.
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Raman K, Chong M, Akhtar-Danesh GG, D'Mello M, Hasso R, Ross S, Xu F, Paré G. Genetic Markers of Inflammation and Their Role in Cardiovascular Disease. Can J Cardiol 2013; 29:67-74. [DOI: 10.1016/j.cjca.2012.06.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 06/29/2012] [Accepted: 06/29/2012] [Indexed: 10/27/2022] Open
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Borbon A, Ruiz M, Bechara J, Aumont B, Chong M, Huntrieser H, Mari C, Reeves CE, Scialom G, Hamburger T, Stark H, Afif C, Jambert C, Mills G, Schlager H, Perros PE. Transport and chemistry of formaldehyde by mesoscale convective systems in West Africa during AMMA 2006. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd017121] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Li JY, Chong M, Yong LT, Tan NC, Iyer G, Soo KC, Tan HK. O131. Giant Ameloblastoma: Is radical resection the choice of treatment? Oral Oncol 2011. [DOI: 10.1016/j.oraloncology.2011.06.242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ivanov I, Zhou L, Huh J, Santori F, Manel N, Chong M, Umesaki Y, Brodie E, Honda K, Littman D. Role of microbiota and transcription factors in control of Th17 cell differentiation. Cytokine 2009. [DOI: 10.1016/j.cyto.2009.07.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sebastian R, Skowronski DM, Chong M, Dhaliwal J, Brownstein JS. Age-related trends in the timeliness and prediction of medical visits, hospitalizations and deaths due to pneumonia and influenza, British Columbia, Canada, 1998-2004. Vaccine 2007; 26:1397-403. [PMID: 18280620 DOI: 10.1016/j.vaccine.2007.11.090] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 11/27/2007] [Accepted: 11/30/2007] [Indexed: 11/30/2022]
Abstract
The influenza immunization program in North America has been primarily designed to provide direct benefit to vaccinated individuals at highest risk of serious influenza outcomes. Some evidence suggests that immunization of certain age groups may also extend indirect protective benefit to vulnerable populations. Our goal was to identify age groups associated earliest with seasonal influenza activity and who may have the greatest indirect impact at the population level. We examined age-based associations between influenza medical visits and population-wide hospitalization/mortality due to pneumonia & influenza (P&I) using administrative datasets in British Columbia, Canada. A peak week was identified for each age group based on the highest rates observed in a given week for that study year. Mean rates at the peak week were averaged over the study years per age group. Timeliness (T) was defined as the mean difference in days between the first peak in influenza medical visits and population-wide P&I hospitalizations/deaths. Poisson regression was applied to calculate prediction (Pr) as the average proportion of deviance in P&I explained by influenza medical visits. T and Pr were derived by age group, and the product (T x Pr) was used as a summary measure to rank potential indirect effects of influenza by age group. Young children (0-23 months) and the elderly (> or = 65 years) had the highest peak rates of P&I hospitalization. Children < 6m and the elderly had the highest peak rates of P&I mortality. We found no significant differences by age for influenza medical visits in predicting population-wide P&I hospitalizations or deaths. School-aged children (5-19 years) showed the best relative combination of T x Pr, followed by preschool-aged children (2-4 years). We conclude that the very young and old suffer the greatest morbidity due to P&I, and an indirect role for school-aged children in anticipating the risk to others warrants further evaluation.
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Peyton PJ, Chong M, Stuart-Andrews C, Robinson GJB, Pierce R, Thompson BR. Measurement of Anesthetics in Blood Using a Conventional Infrared Clinical Gas Analyzer. Anesth Analg 2007; 105:680-7. [PMID: 17717223 DOI: 10.1213/01.ane.0000278126.94161.33] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Measurement of the partial pressure of volatile anesthetics in blood is usually done using a "headspace equilibration" method with gas chromatography. However, it is not often performed in clinical studies because of the technical, equipment, and logistic requirements. To improve the accessibility of this measurement, we tested the use of a common infrared clinical gas analyzer, the Datex-Ohmeda Capnomac, for this purpose. METHODS After characterization of the linearity of the device in measuring the volatile anesthetic concentration in the presence of nitrous oxide, carbon dioxide, and water vapor, blood was tonometered with known concentrations of sevoflurane (actual value between 0.5% and 5.0%) in oxygen and oxygen/nitrous oxide mixtures, as well as mixtures of isoflurane and desflurane in oxygen. RESULTS Mean bias (standard deviation) overall for sevoflurane in oxygen relative to the tonometered reference partial pressure was -4.5 (4.8%) of the actual concentration. This was not altered significantly by measurement in 40% oxygen/60% nitrous oxide. For isoflurane and desflurane it was -3.9 (3.3%) and -4.6 (3.8%), respectively, of the actual concentration. CONCLUSIONS The accuracy and precision of measurement of volatile anesthetic gas partial pressures in blood by a double headspace equilibration technique, using a clinical infrared gas analyzer, were comparable to that achieved by previous studies using gas chromatography.
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Dobson G, Chong M, Walker M, Petrasek P, Johnston CR, Tyberg JV, Karamanoglu M. Characterization of the Upper Limb Arterial Properties during Reactive Hyperemia. ACTA ACUST UNITED AC 2007; 7:127-34. [PMID: 17676391 DOI: 10.1007/s10558-007-9032-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The radial artery (RA) pressure waveform is commonly used to reconstruct the central aortic pressure waveform. Because the RA pressure waveform has been used as input to this process, its features that are dependent on the local arterial properties can influence the final reconstructed aortic waveform. In this study, we determined the effects of altered upper limb pulse wave velocity (PWV) and local wave reflection parameters on RA pressure waveform augmentation (RA-AIx). Twenty healthy volunteers (10 men) between the ages of 18 and 35 years of age were recruited. Simultaneous pressure waveforms were acquired using arterial tonometers from the right carotid and the radial arteries, prior to and following tourniquet induced hyperemia. The phase velocities from the pressure wave transfer function were used to estimate the pulse wave velocity (PWV(infinity)), the local reflection coefficient (Gamma) and an estimate of the terminal impedance of the upper limbs, PWV(0+). The RA-AIx was represented as a linear, three-parameter model that included the input (the AIx of the carotid artery pressure waveform, CA-AIx), the Gamma and PWV(infinity) of the arm. Tourniquet induced hyperemia did not alter Gamma but reduced PWV(infinity), and PWV(0+) and increased RA-AIx. Multiple linear regression analysis indicated that RA-AIx was increased by high levels of CA-AIx and PWV(infinity) and decreased by elevated Gamma. The relative weighing of CA-AIx, Gamma and PWV(infinity) on RA-AIx were 3:2:1, respectively. The AIx of RA is determined to an equal extent by the input and local factors. Interpretation of the AIx of the RA and the reconstructed central aortic waveform should be made in the context of this relationship.
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Dobson G, Chong M, Walker M, Johnston C, Karamanoglu M. A simple means of evaluating peri-operative endothelial function? Can J Anaesth 2006. [DOI: 10.1007/bf03016942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Choi P, Snyder H, Petrucelli L, Theisler C, Chong M, Zhang Y, Lim K, Chung KKK, Kehoe K, D'Adamio L, Lee JM, Cochran E, Bowser R, Dawson TM, Wolozin B. SEPT5_v2 is a parkin-binding protein. ACTA ACUST UNITED AC 2004; 117:179-89. [PMID: 14559152 DOI: 10.1016/s0169-328x(03)00318-8] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Mutations in parkin are associated with various inherited forms of Parkinson's disease (PD). Parkin is a ubiquitin ligase enzyme that catalyzes the covalent attachment of ubiquitin moieties onto substrate proteins destined for proteasomal degradation. The substrates of parkin-mediated ubiquitination have yet to be completely identified. Using a yeast two-hybrid screen, we isolated the septin, human SEPT5_v2 (also known as cell division control-related protein 2), as a putative parkin-binding protein. SEPT5_v2 is highly homologous to another septin, SEPT5, which was recently identified as a target for parkin-mediated ubiquitination. SEPT5_v2 binds to parkin at the amino terminus and in the ring finger domains. Several lines of evidence have validated the putative link between parkin and SEPT5_v2. Parkin co-precipitates with SEPT5_v2 from human substantia nigra lysates. Parkin ubiquitinates SEPT5_v2 in vitro, and both SEPT5_v1 and SEPT5_v2 accumulate in brains of patients with ARJP, suggesting that parkin is essential for the normal metabolism of these proteins. These findings suggest that an important relationship exists between parkin and septins.
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Soula S, Chauzy S, Chong M, Coquillat S, Georgis JF, Seity Y, Tabary P. Surface precipitation electric current produced by convective rains during the Mesoscale Alpine Program. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jd001588] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Choi P, Golts N, Snyder H, Chong M, Petrucelli L, Hardy J, Sparkman D, Cochran E, Lee JM, Wolozin B. Co-association of parkin and alpha-synuclein. Neuroreport 2001; 12:2839-43. [PMID: 11588587 DOI: 10.1097/00001756-200109170-00017] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Parkin and alpha-synuclein are two proteins that are associated with the pathophysiology of Parkinson's disease (PD). Parkin is present in Lewy bodies and axonal spheroids in brains affected by PD, and mutations in parkin cause hereditary forms of Parkinsonism. Alpha-synuclein is a major component of Lewy bodies and is associated with rare cases of PD. We now show that parkin binds to alpha-synuclein, including conditions associated with alpha-synuclein aggregation. Parkin and alpha-synuclein complexes were observed in BE-M17 cells under basal conditions, in BE- M17 cells under oxidative conditions and in brains from control or PD donors. Double staining of PD brains shows parkin and alpha-synuclein co-localize to the same pathological structures (both Lewy bodies and axonal spheroids). These results suggest that parkin interacts with alpha-synuclein and could contribute to the pathophysiology of PD more generally than was previously considered.
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Abstract
PURPOSE To determine the efficacy of arterial phase helical computed tomography (CT) for the depiction of small pancreatic arteries. MATERIALS AND METHODS Arterial phase helical CT (3-mm collimation, 1-mm reconstruction interval) was performed during power injection of 180 mL of ioversol at 5 mL/sec. Two radiologists reviewed 100 consecutive arterial phase helical CT scans of the pancreas in patients with normal glands and recorded the frequency of visualization of the major visceral (celiac, hepatic, splenic, gastroduodenal, superior mesenteric) and small pancreatic (dorsal pancreatic, right branch of the dorsal pancreatic, pancreaticomagna, caudal pancreatic, transverse pancreatic, anterior and posterior arcade, and inferior pancreaticoduodenal) arteries. RESULTS Scans in 87 patients were technically satisfactory and were included in the analysis. The major visceral arteries were seen in all patients. The following secondary pancreatic arteries were seen: dorsal pancreatic, 82 (94%) patients; pancreaticomagna, 45 (52%); caudal pancreatic, 34 (39%); transverse pancreatic, 36 (41%); right branch of the dorsal pancreatic, eight (9%); anterior arcade, 47 (54%); posterior arcade, 63 (72%); and inferior pancreaticoduodenal, 73 (84%). CONCLUSION Small pancreatic arteries can be delineated on arterial phase helical CT scans by using optimized techniques.
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Chauzy S, Chong M, Delannoy A, Despiau S. The June 22 tropical squall line observed during COPT 81 experiment: Electrical signature associated with dynamical structure and precipitation. ACTA ACUST UNITED AC 1985. [DOI: 10.1029/jd090id04p06091] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Testud J, Chong M. Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data. Part I: Filtering, Interpolating and Differentiating the Raw Data. ACTA ACUST UNITED AC 1983. [DOI: 10.1175/1520-0450(1983)022<1204:tdwfaf>2.0.co;2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Missirlis YF, Chong M. Aortic valve mechanics--Part I: material properties of natural porcine aortic valves. JOURNAL OF BIOENGINEERING 1978; 2:287-300. [PMID: 711721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A new methodology has been developed whereby the inhomogeneous and anisotropic aspects of an irregularly surfaced organ component have been incorporated in establishing the material properties of its tissue. Specifically the direction-dependent post-transition elastic moduli have been calculated from microtensile experiments for the porcine aortic valve leaflets with an average of ECIRC/ERAD = 3.2. Furthermore pressure-strain data have been measured for a grid of points on the surface of a porcine aortic valve and an isostrain map has been developed for P = 80 mm. Hg. These data are used for the stress analysis of porcine aortic valves which is the subject of a companion paper.
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Chong M, Eng M, Missirlis YF. Aortic valve mechanics. Part II: a stress analysis of the porcine aortic valve leaflets in diastole. BIOMATERIALS, MEDICAL DEVICES, AND ARTIFICIAL ORGANS 1978; 6:225-44. [PMID: 728516 DOI: 10.3109/10731197809118703] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The stress analysis of the porcine aortic valve leaflets in diastole at 80 mm Hg pressure in-vitro is presented. Incorporation of local geometrical asymmetry, material inhomogeneity, anistropy and non-linearity are applied. The stress theory used is a modified form of the thin membrane stress theory for a homogeneous linearly elastic and orthotropic lamina. Modifications are made so that the Hooke's law constitutive equations of stress may be applied to the inhomogeneous, non-lineary elastic and orthotropic thin (membrane) aortic valve leaflets. Stress calculations are made on the premise that the valve is in pre-transition (i.e. low elastic modulus) in the circumferential direction and post-transition (i.e. high elastic modulus) in the radial direction. It is shown that sigmaCIR less than 1 gm/mm2, and for most of the noncoronary leaflet, 0 less than sigmaRAD less than 30 gm/mm2. The areas of highest stress concentrations are in the areas of mutual leaflet coaptation near the Node of Arantii. A progressive increase of radial stresses from the sinus-annulus edge toward the node is observed.
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