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Abstract
Plagiarism has been a problem plaguing academia for centuries. The Internet has made it easier than ever to copy material from one electronic document and paste it into another. Many cases are unintentional, as writers are unaware of the rules regarding plagiarism. This paper provides an overview of plagiarism and describes a project in which librarians partnered with the assistant dean of a graduate science program to educate students about the perils of plagiarism and encourage ethical writing practices.
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Sorensen K. Bone Health. JOURNAL OF CONSUMER HEALTH ON THE INTERNET 2011. [DOI: 10.1080/15398285.2011.573373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Sorensen K, Radha S, Siddiqui H. Management of Non-Spinal Injury Pressure Sore Referrals. Int J Surg 2010. [DOI: 10.1016/j.ijsu.2010.07.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Glassman NR, Habousha RG, Minuti A, Schwartz R, Sorensen K. Let me show you how it's done! Desktop sharing for distance learning from the D. Samuel Gottesman Library. Med Ref Serv Q 2009; 28:297-308. [PMID: 20183031 PMCID: PMC2829731 DOI: 10.1080/02763860903248979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Due to the proliferation of electronic resources, fewer users visit the library. Traditional classroom instruction and in-person consultations are no longer sufficient in assisting library users. Librarians are constantly seeking new ways to interact with patrons and facilitate efficient use of electronic resources. This article describes the development, implementation, and evaluation of a project in which desktop-sharing software was used to reach out to users at remote locations. Various ways of using this tool are described, and challenges and implications for future expansion are discussed.
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Sorensen K. Genetic enhancements and expectations. JOURNAL OF MEDICAL ETHICS 2009; 35:433-435. [PMID: 19567693 DOI: 10.1136/jme.2008.026435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Some argue that genetic enhancements and environmental enhancements are not importantly different: environmental enhancements such as private schools and chess lessons are simply the old-school way to have a designer baby. I argue that there is an important distinction between the two practices--a distinction that makes state restrictions on genetic enhancements more justifiable than state restrictions on environmental enhancements. The difference is that parents have no settled expectations about genetic enhancements.
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Larsen LU, Sloth E, Petersen OB, Pedersen TF, Sorensen K, Uldbjerg N. Systolic myocardial velocity alterations in the growth-restricted fetus with cerebroplacental redistribution. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2009; 34:62-67. [PMID: 19489024 DOI: 10.1002/uog.6375] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
OBJECTIVES Intrauterine growth restriction (IUGR) is associated with cerebroplacental redistribution (CPR), fetal stress and poor outcome, all of which may be related to dysfunction of the fetal myocardium. The aim of this study was to specifically assess myocardial function in IUGR fetuses with CPR in comparison with normal fetuses using color Doppler myocardial imaging (CDMI). METHODS CDMI was used to evaluate and compare myocardial velocities in the left and right ventricles in normal fetuses and in IUGR fetuses with CPR. Peak systolic tissue velocities (S') were acquired from both ventricular free walls in 20 IUGR fetuses (gestational age at scan ranged from 26 + 1 to 34 + 6 weeks, with serial measurements obtained in nine) and 42 normal fetuses (35 at week 28, with the remaining seven undergoing serial scans every 4 weeks, ranging from 18 + 6 to 39 + 1 weeks). Umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) flows were also recorded. RESULTS Left and right S' increased with gestational age in normal pregnancy. Fetuses with IUGR and CPR had lower left ventricular S' than normal fetuses (mean, 2.41 (95% CI, 1.96-2.86) cm/s vs. 3.30 (95% CI, 3.05-3.55) cm/s; P = 0.0006). This reduction in S' correlated with the grade of UA flow abnormality (P = 0.0002). Fetuses with reversed diastolic UA flow had significantly lower left S' (mean, 2.0 (95% CI, 1.4-2.6) cm/s; P = 0.001) than normal fetuses. There was no correlation between left S' and MCA pulsatility index (P = 0.37) in the IUGR-CPR group, but there was a reduction in S' approaching statistical significance in fetuses with reversed DV flow in comparison to those without it (P = 0.09). Right S' was similar in the two study groups and did not correlate with worsening UA flow class. All fetuses with a left S' below 1.6 cm/s and reversed UA flow died in the perinatal period. CONCLUSIONS CDMI facilitates acquisition of fetal myocardial ventricular S'. The combination of IUGR and CPR is associated with a reduced left ventricular S', especially in those with reversed UA flow. In this subgroup a left S' below 1.6 cm/s seemed to predict mortality in the perinatal period.
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Dabernig J, Sorensen K, Shaw-Dunn J, Hart AM. The thin circumflex scapular artery perforator flap. J Plast Reconstr Aesthet Surg 2007; 60:1082-96. [PMID: 17825774 DOI: 10.1016/j.bjps.2006.10.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2005] [Revised: 07/18/2006] [Accepted: 10/13/2006] [Indexed: 11/28/2022]
Abstract
The development of microsurgery has most recently been focused upon the evolution of perforator flaps, with the aim of minimising donor site morbidity, and avoiding the transfer of functionally unnecessary tissues. The vascular basis of perforator flaps also facilitates radical primary thinning prior to flap transfer, when appropriate. Based upon initial clinical observations, cadaveric, and radiological studies, we describe a new, thin, perforator flap based upon the circumflex scapular artery (CSA). A perforator vessel was found to arise within 1.5cm of the CSA bifurcation (arising from the main trunk, or the descending branch). The perforator arborises into the sub-dermal vascular plexus of the dorsal scapular skin, permitting the elevation and primary thinning of a skin flap. This thin flap has been employed in a series of five clinical cases to reconstruct defects of the axilla (two cases of hidradenitis suppurativa; pedicled transfers), and upper limb (one sarcoma, one brachial to radial artery flowthrough revascularisation plus antecubital fossa reconstruction, and one hand reconstruction with a chimeric flap incorporating vascularised bone, fascia, and thin skin flaps; free tissue transfers). No intramuscular perforator dissection is required; pedicle length is 8-10cm and vessel diameter 2-4mm. There was no significant peri-operative complication or flap failure, all donor sites were closed primarily, patient satisfaction was high, and initial reconstructive aims were achieved in all cases. Surgical technique, and the vascular basis of the flap are described. The thin circumflex scapular artery perforator flap requires no intramuscular dissection yet provides high quality skin (whose characteristics can be varied by orientation of the skin paddle), and multiple chimeric options. The donor site is relatively hair-free, has favourable cosmesis and no known functional morbidity. This flap represents a promising addition to the existing range of perforator flaps.
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Sorensen K, Dabernig J, Hart AM, Watson S. Harvesting a dorsal digital vein and its intercapitular branch at the MCPJ level in digital replantation. J Plast Reconstr Aesthet Surg 2007; 60:959-60. [PMID: 17400042 DOI: 10.1016/j.bjps.2007.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 02/17/2007] [Indexed: 11/28/2022]
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Schmidt MR, Smerup M, Konstantinov IE, Shimizu M, Li J, Cheung M, White PA, Kristiansen SB, Sorensen K, Dzavik V, Redington AN, Kharbanda RK. Intermittent peripheral tissue ischemia during coronary ischemia reduces myocardial infarction through a KATP-dependent mechanism: first demonstration of remote ischemic perconditioning. Am J Physiol Heart Circ Physiol 2006; 292:H1883-90. [PMID: 17172279 DOI: 10.1152/ajpheart.00617.2006] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Remote ischemic preconditioning reduces myocardial infarction (MI) in animal models. We tested the hypothesis that the systemic protection thus induced is effective when ischemic preconditioning is administered during ischemia (PerC) and before reperfusion and examined the role of the K(+)-dependent ATP (K(ATP)) channel. Twenty 20-kg pigs were randomized (10 in each group) to 40 min of left anterior descending coronary artery occlusion with 120 min of reperfusion. PerC consisted of four 5-min cycles of lower limb ischemia by tourniquet during left anterior descending coronary artery occlusion. Left ventricular (LV) function was assessed by a conductance catheter and extent of infarction by tetrazolium staining. The extent of MI was significantly reduced by PerC (60.4 +/- 14.3 vs. 38.3 +/- 15.4%, P = 0.004) and associated with improved functional indexes. The increase in the time constant of diastolic relaxation was significantly attenuated by PerC compared with control in ischemia and reperfusion (P = 0.01 and 0.04, respectively). At 120 min of reperfusion, preload-recruitable stroke work declined 38 +/- 6% and 3 +/- 5% in control and PerC, respectively (P = 0.001). The force-frequency relation was significantly depressed at 120 min of reperfusion in both groups, but optimal heart rate was significantly lower in the control group (P = 0.04). There were fewer malignant arrhythmias with PerC during reperfusion (P = 0.02). These protective effects of PerC were abolished by glibenclamide. Intermittent limb ischemia during myocardial ischemia reduces MI, preserves global systolic and diastolic function, and protects against arrhythmia during the reperfusion phase through a K(ATP) channel-dependent mechanism. Understanding this process may have important therapeutic implications for a range of ischemia-reperfusion syndromes.
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Larsen LU, Petersen OB, Norrild K, Sorensen K, Uldbjerg N, Sloth E. Strain rate derived from color Doppler myocardial imaging for assessment of fetal cardiac function. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2006; 27:210-3. [PMID: 16435318 DOI: 10.1002/uog.2669] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
OBJECTIVE Color Doppler myocardial imaging (CDMI) is a new multigated method that allows direct analysis of myocardial motion. It is superior to pulsed-wave tissue Doppler in its ability to generate new and important indices of myocardial function such as strain, strain rate and tissue tracking. The purpose of this study was to assess the feasibility of CDMI in the fetal heart. METHODS Three normal fetuses of gestational ages 20 + 1, 28 + 1 and 36 + 0 weeks and a fetus of 20 + 3 weeks with aortic valve atresia were studied. Velocity data were acquired from the apical four-chamber view using a Vivid 7 ultrasound platform with integrated software for CDMI and with frame rates around 200/s. Data were post-processed using dedicated software and with the sample area placed at the subvalvular and middle part of the septum and the ventricular walls. RESULTS CDMI was feasible in all fetuses. The fetus with aortic valve atresia had severely reduced strain rate of the left ventricular wall. CONCLUSIONS Using this new technique it is possible to obtain information on the global and regional contractility of the fetal heart and thereby gain new insights into the physiology of the fetal cardiovascular system. CDMI is a promising new method for monitoring at-risk fetuses.
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Coleman MA, Yin E, Peterson LE, Nelson D, Sorensen K, Tucker JD, Wyrobek AJ. Low-dose irradiation alters the transcript profiles of human lymphoblastoid cells including genes associated with cytogenetic radioadaptive response. Radiat Res 2005; 164:369-82. [PMID: 16187739 DOI: 10.1667/rr3356.1] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Low-dose ionizing radiation alters the gene expression profiles of mammalian cells, yet there is little understanding of the underlying cellular mechanisms responsible for these changes or of their consequences for genomic stability. We investigated the cytogenetic adaptive response of human lymphoblastoid cell lines exposed to 5 cGy (priming dose) followed by 2 Gy (challenge dose) compared to cells that received a single 2-Gy dose to (a) determine how the priming dose influences subsequent gene transcript expression in reproducibly adapting and non-adapting cell lines, and (b) identify gene transcripts that are associated with reductions in the magnitude of chromosomal damage after the challenge dose. The transcript profiles were evaluated using oligonucleotide arrays and RNA obtained 4 h after the challenge dose. A set of 145 genes (false discovery rate = 5%) with transcripts that were affected by the 5-cGy priming dose fell into two categories: (a) a set of common genes that were similarly modulated by the 5-cGy priming dose irrespective of whether the cells subsequently adapted or not and (b) genes with differential transcription in accordance with the cell lines that showed either adaptive or non-adaptive outcomes. The common priming-dose response genes showed up-regulation for protein synthesis genes and down-regulation of metabolic and signal transduction genes (>10-fold differences). The genes associated with subsequent adaptive and non-adaptive outcomes involved DNA repair, stress response, cell cycle control and apoptosis. Our findings support the importance of TP53-related functions in the control of the low-dose cytogenetic radioadaptive response and suggest that certain low-dose-induced alterations in cellular functions are predictive for the risk of subsequent genomic damage.
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Dugan LC, Pattee MS, Williams J, Eklund M, Sorensen K, Bedford JS, Christian AT. Polymerase chain reaction-based suppression of repetitive sequences in whole chromosome painting probes for FISH. Chromosome Res 2005; 13:27-32. [PMID: 15791409 DOI: 10.1007/s10577-005-2349-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 09/17/2004] [Accepted: 10/19/2004] [Indexed: 11/28/2022]
Abstract
We have developed a method to suppress the PCR amplification of repetitive sequences in whole chromosome painting probes by adding Cot-1 DNA to the amplification mixture. The repetitive sequences in the Cot-1 DNA bind to their homologous sequences in the probe library, prevent the binding of primers, and interfere with extension of the probe sequences, greatly decreasing PCR efficiency selectively across these blocked regions. A second labelling reaction is then done and this product is resuspended in FISH hybridization mixture without further addition of blocking DNA. The hybridization produces little if any non-specific binding on any other chromosomes. We have been able to successfully use this procedure with both human and rat chromosome probes. This technique should be applicable in producing probes for CGH, M-FISH and SKY, as well as reducing the presence of repetitive DNA in genomic libraries.
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Dorup I, Levitt G, Sullivan I, Sorensen K. Prospective longitudinal assessment of late anthracycline cardiotoxicity after childhood cancer: the role of diastolic function. Heart 2004; 90:1214-6. [PMID: 15367528 PMCID: PMC1768494 DOI: 10.1136/hrt.2003.027516] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Levitt GA, Dorup I, Sorensen K, Sullivan I. Does anthracycline administration by infusion in children affect late cardiotoxicity? Br J Haematol 2004; 124:463-8. [PMID: 14984495 DOI: 10.1111/j.1365-2141.2004.04803.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The severity of late cardiotoxicity after anthracycline treatment for childhood cancer relates mainly to the cumulative anthracycline dose received, but all dose ranges cause some cardiac dysfunction. Anthracycline administration by infusion in order to lower peak drug concentration has been used in an attempt to reduce cardiotoxicity. Cardiac performance was assessed by echocardiography in children who were relapse-free survivors of treatment for acute lymphoblastic leukaemia (ALL). They received the same cumulative anthracycline dose (daunorubicin 180 mg/m2) either by bolus injection (UKALL X protocol, n = 40) or by infusion (UKALL XI protocol, n = 71) with a follow-up duration of 5.3 +/- 2.0 and 5.4 +/- 1.0 years respectively. On analysis, both the bolus administration and infusion groups showed similar mild impairment of cardiac performance, characterized by increased left ventricular end systolic stress and impaired left ventricular function. In conclusion, subclinical abnormality of left ventricular performance was confirmed in both groups despite the relatively modest cumulative anthracycline dose received. We were unable to demonstrate an advantage of anthracycline administration by 6-h infusion with respect to late cardiotoxicity at this dose.
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Brocchi E, Sorensen K, Mackay D. The use of serology as part of the exit strategy to the 1996 epidemic of FMD in the Balkans. DEVELOPMENTS IN BIOLOGICALS 2004; 119:283-92. [PMID: 15742640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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Kharbanda RK, Mortensen UM, White PA, Kristiansen SB, Schmidt MR, Hoschtitzky JA, Vogel M, Sorensen K, Redington AN, MacAllister R. Transient limb ischemia induces remote ischemic preconditioning in vivo. Circulation 2002; 106:2881-3. [PMID: 12460865 DOI: 10.1161/01.cir.0000043806.51912.9b] [Citation(s) in RCA: 532] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND Ischemic preconditioning reduces local tissue injury caused by subsequent ischemia-reperfusion (IR), but may also have a salutary effect on IR injury of tissues remote from those undergoing preconditioning. We tested the hypothesis that limb ischemia induces remote preconditioning, reduces endothelial IR injury in humans, and reduces experimental myocardial infarct size. METHODS AND RESULTS Endothelial IR injury of the human forearm was induced by 20 minutes of upper limb ischemia (inflation of a blood pressure cuff to 200 mm Hg) followed by reperfusion. Remote preconditioning was induced by three 5-minute cycles of ischemia of the contralateral limb. Venous occlusion plethysmography was used to assess forearm blood flow in response to acetylcholine at baseline and 15 minutes after reperfusion. Experimental myocardial infarction was achieved by 40 minutes of balloon occlusion of the left anterior descending artery in 15-kg pigs. Remote preconditioning was induced by four 5-minute cycles of lower limb ischemia. Triphenyltetrazolium staining was used to assess the extent of myocardial infarction. In the human study, the response to acetylcholine was significantly attenuated in the control group after 15 minutes' reperfusion, but remote preconditioning prevented this reduction. Limb ischemia caused a significant reduction in the extent of myocardial infarction relative to the area at risk compared with control (26+/-9% versus 53+/-8%, P<0.05). CONCLUSION Remote ischemic preconditioning prevents IR-induced endothelial dysfunction in humans and reduces the extent of myocardial infarction in experimental animals. Transient limb ischemia is a simple preconditioning stimulus with important potential clinical applications.
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Glavind-Kristensen M, Brix-Christensen V, Toennesen E, Ravn HB, Forman A, Sorensen K, Hjortdal VE. Pulmonary endothelial dysfunction after cardiopulmonary bypass in neonatal pigs. Acta Anaesthesiol Scand 2002; 46:853-9. [PMID: 12139542 DOI: 10.1034/j.1399-6576.2002.460716.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND In neonatal pigs cardiopulmonary bypass (CPB) is associated with endothelial dysfunction in isolated large pulmonary arteries. It is, however, of great importance if this functional change extends to the small pulmonary resistance arteries, which are the key regulators of pulmonary flow and pressure. The aim of this study was to assess changes in pulmonary microvascular function after CPB using a clinically relevant pediatric procedure. METHODS From three groups of neonatal pigs (CPB-, sham- and control group) pulmonary resistance arteries and systemic resistance arteries (from skeletal muscle) were isolated and mounted as ring preparations in wire myographs. Vessel diameters were less than 500 microm. Concentration-response curves were constructed for norepinephrine (NA), vasopressin (Vp), and the thromboxane A2-analog U46619, while the endothelium-dependent and -independent vasodilator functions were assessed as responses to acetylcholine and nitric oxide (NO). RESULTS Maximum pulmonary vasodilator response to acetylcholine was attenuated after CPB compared with sham-operated and control animals (P=0.04). NO-induced relaxation, and contractile responses to NA, Vp, and U46619 were not influenced by CPB. In systemic arteries no changes in contractile or relaxant responses were seen after CPB. CONCLUSION CPB seems to induce pulmonary endothelial dysfunction in pulmonary but not peripheral resistance arteries in neonatal piglets.
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Good VD, Clarke IC, Gustafson GA, Downs B, Anissian L, Sorensen K. Wear of ultra-high molecular weight polyethylene and polytetrafluoroethylene in a hip simulator: a dose-response study of protein concentration. ACTA ORTHOPAEDICA SCANDINAVICA 2000; 71:365-9. [PMID: 11028884 DOI: 10.1080/000164700317393358] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Charnley's laboratory wear studies of non-gamma sterilized polytetrafluoroethylene (PTFE) and polyethylene (PE) found that the PTFE to PE wear-rate ratio of 250:1 was much higher than the in-vivo wear ratio of 20:1. Tests of PTFE and PE in our laboratory showed a wear ratio of 150:1, using bovine serum as the lubricant and 190:1 with water as the lubricant. Our hypothesis was that the wear-rates of PTFE and PE cup materials were related to the concentration of protein in the serum. We studied the wear behavior of PTFE and PE cups in varied protein concentrations, using 4 femoral head sizes to validate the clinical range reported by Charnley. The PTFE wear-rates increased with increasing protein concentration and conversely, PE wear-rates decreased with increasing protein concentration. This inverse relationship made it possible to bring the wear ratio closer to the desired clinical wear ratio. We found that the clinically relevant PTFE/PE wear ratio corresponded to 3-10 mg/mL of protein in bovine serum.
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Sorensen K. Weight watchers. Nurs Stand 1999; 13:18. [PMID: 10085893 DOI: 10.7748/ns.13.18.18.s31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Littlefield LG, McFee AF, Salomaa SI, Tucker JD, Inskip PD, Sayer AM, Lindholm C, Mäkinen S, Mustonen R, Sorensen K, Tekkel M, Veidebaum T, Auvinen A, Boice JD, Makinen S. Do Recorded Doses Overestimate True Doses Received by Chernobyl Cleanup Workers? Results of Cytogenetic Analyses of Estonian Workers by Fluorescence In Situ Hybridization. Radiat Res 1998. [DOI: 10.2307/3579859] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Littlefield LG, McFee AF, Salomaa SI, Tucker JD, Inskip PD, Sayer AM, Lindholm C, Mäkinen S, Mustonen R, Sorensen K, Tekkel M, Veidebaum T, Auvinen A, Boice JD. Do recorded doses overestimate true doses received by Chernobyl cleanup workers? Results of cytogenetic analyses of Estonian workers by fluorescence in situ hybridization. Radiat Res 1998; 150:237-49. [PMID: 9692369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Studies of workers who were sent to Chernobyl after the 1986 reactor accident are being conducted to provide a better understanding of the effects of chronic low-dose radiation exposures. A crucial component to these investigations is an accurate assessment of the radiation doses received during the cleanup activities. To provide information on biological measurements of dose, fluorescence in situ hybridization (FISH) with whole-chromosome painting probes has been applied to quantify stable chromosome aberrations (translocations and insertions) among a defined cohort of 4,833 cleanup workers from Estonia. Cytogenetic analysis of 48-h lymphocyte cultures from 118 Estonian cleanup workers (10.3 cGy mean recorded dose; 25 cGy maximum), 29 Estonian population controls and 21 American controls was conducted by three laboratories. More than 258,000 painted metaphases were evaluated. Overall, we observed lower translocation frequencies than has been reported in previous studies using FISH among Chernobyl cleanup workers. In our data, a clear association with increased levels of translocations was seen with increasing age at blood drawing. There was no correlation, however, between aberration frequency and recorded measurements of physical dose or any category of potential high-dose and high-dose-rate exposure such as being sent to Chernobyl in 1986, working on the roof near the damaged nuclear reactor, working in special zones or having multiple tours. In fact, the translocation frequency was lower among the exposed workers than the controls, though not significantly so. To estimate the level of effect that would have been expected in a population of men having an average dose of approximately 10 cGy, blood from six donors was exposed to low-LET radiation, and more than 32,000 metaphases were scored to estimate dose-response coefficients for radiation-induced translocations in chromosome pairs 1, 2 and 4. Based on these results, we estimate that had this group of 118 men received an average whole-body dose of 10-11 cGy, as chronic or acute exposures, an increase in the mean frequency of chromosome translocations of more than 40-65% would have been observed in their lymphocytes compared to findings in nonirradiated controls. In spite of evaluating more than a quarter of a million metaphases, we were unable to detect any increase in the mean, median or range in chromosome aberrations in lymphocyte cultures from a group of Estonian men who took part in the cleanup of the Chernobyl nuclear power site and those who did not. We conclude that it is likely that recorded doses for these cleanup workers overestimate their average bone marrow doses, perhaps substantially. These results are consistent with several negative studies of cancer incidence in Chernobyl cleanup workers and, if borne out, suggest that future studies may not be sufficiently powerful to detect increases in leukemia or cancer, much less distinguish differences between the effects of chronic compared to brief radiation exposures.
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White PA, Brookes CI, Ravn HB, Stenbøg EE, Christensen TD, Chaturvedi RR, Sorensen K, Hjortdal VE, Redington AN. The effect of changing excitation frequency on parallel conductance in different sized hearts. Cardiovasc Res 1998; 38:668-75. [PMID: 9747434 DOI: 10.1016/s0008-6363(98)00052-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE An important component of the ventricular volume measured using the conductance catheter technique is due to parallel conductance (Vc), which results from the extension of the electric field beyond the ventricular blood pool. Parallel conductance volume is normally estimated using the saline dilution method (Vc(saline dilution)), in which the conductivity of blood in the ventricle is transiently increased by injection of hypertonic saline. A simpler alternative has been reported by Gawne et al. [12]. Vc(dual frequency) is estimated from the difference in total conductance measured at two exciting frequencies and the method is based on the assumption that parallel conductance is mainly capacitive and hence is negligible at low frequency. The objective of this study was to determine whether the dual frequency technique could be used to substitute the saline dilution method to estimate Vc in different sized hearts. METHODS The accuracy and linearity of a custom-built conductance catheter (CC) system was initially assessed in vitro. Subsequently, a CC and micromanometer were inserted into the left ventricle of seven 5 kg pigs (group 1) and six 50 kg pigs (group 2). Cardiac output was determined using thermodilution (group 1) and an ultrasonic flow probe (group 2) from which the slope coefficient (alpha) was determined. Steady state measurements and Vc estimated using saline dilution were performed at frequencies in the range of 5-40 kHz. All measurements were made at end-expiration. Finally, Vc was estimated from the change in end-systolic conductance between 5 kHz and 40 kHz using the dual frequency technique of Gawne et al. [12]. RESULTS There was no change in measured volume of a simple insulated cylindrical model when the stimulating frequency was varied from 5-40 kHz. Vc(saline dilution) varied significantly with frequency in group 1 (8.63 +/- 2.74 ml at 5 kHz; 11.51 +/- 2.65 ml at 40 kHz) (p = 0.01). Similar results were obtained in group 2 (69.43 +/- 27.76 ml at 5 kHz; 101.24 +/- 15.21 ml at 40 kHz) (p < 0.001). However, the data indicate that the resistive component of the parallel conductance is substantial (Vc at 0 Hz estimated as 8.01 ml in group 1 and 62.3 ml in group 2). There was an increase in alpha with frequency in both groups but this did not reach significance. The correspondence between Vc(dual frequency) and Vc(saline dilution) methods was poor (group 1 R2 = 0.69; group 2 R2 = 0.22). CONCLUSION At a lower excitation frequency of 5 kHz a smaller percentage of the electric current extends beyond the blood pool so parallel conductance is reduced. While parallel conductance is frequency dependent, it has a substantial resistive component. The dual frequency method is based on the assumption that parallel conductance is negligible at low frequencies and this is clearly not the case. The results of this study confirm that the dual frequency technique cannot be used to substitute the saline dilution technique.
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Steenland K, Cedillo L, Tucker J, Hines C, Sorensen K, Deddens J, Cruz V. Thyroid hormones and cytogenetic outcomes in backpack sprayers using ethylenebis(dithiocarbamate) (EBDC) fungicides in Mexico. ENVIRONMENTAL HEALTH PERSPECTIVES 1997; 105:1126-30. [PMID: 9349837 PMCID: PMC1470391 DOI: 10.1289/ehp.971051126] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Ethylenebis(dithiocarbamate) (EBDC) fungicides are used heavily in the United States. EBDCs (e.g., mancozeb, maneb) are metabolized to ethylene thiourea (ETU). The EPA classifies ETU as a carcinogen, based on thyroid and other cancers in rodents, and has restricted the use of EBDCs, while requiring workers to use protective equipment. There are no data on the potential carcinogenicity of EBDCs in humans, and there is only one study on human genotoxicity. ETU is known to cause decreases of thyroxine (T4) and increases in thyroid-stimulating hormone (TSH) in rodents. We have studied cytogenetic outcomes and serum thyroid hormone levels among 49 heavily exposed workers without protective equipment spraying EBDC on tomatoes in Mexico. We also studied 14 lightly exposed landowners and 31 nonexposed controls. Urinary ETU was used to compare exposure between groups. We found an increase in TSH (p = 0.05) among applicators compared to controls, but no decrease in thyroid hormone (T4). We found increases in sister chromatid exchange (p = 0.03) and in chromosome translocations (chromosome aberrations that persist through cell division) for applicators compared to controls (p = 0.05). However, the subset of reciprocal translocations showed a lesser increase (p = 0.24). Our data suggest that EBDCs affect the thyroid gland and the lymphocyte genome among heavily exposed workers. However, our data are limited to subclinical outcomes, are of borderline statistical significance, and should be interpreted with caution.
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Rao SK, Mathrubutham M, Karteron A, Sorensen K, Cohen JR. A versatile microassay for elastase using succinylated elastin. Anal Biochem 1997; 250:222-7. [PMID: 9245442 DOI: 10.1006/abio.1997.2223] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have developed a rapid, versatile, and sensitive elastase assay that is based on the measurement of primary amines that are exposed due to enzymatic degradation of proteins, using succinylated elastin as the substrate for elastase. After incubation with elastase the degree of digestion is determined with trinitrobenzene sulfonic acid. The assay is rapid and sensitive, detecting elastase down to 1 ng/ml, and is linear up to enzyme concentrations of 10 microg/ml. The assay is carried out in microtiter plate wells and therefore offers the potential for assaying numerous samples of small volume. The use of succinylated elastin shows specificity for elastase over the control protease, trypsin. This assay is also versatile because it can be applied to samples such as cell culture supernatants, blood plasma, tissue biopsies, and tissue homogenates.
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Sorensen K, Levitt G, Bull C, Chessells J, Sullivan I. Anthracycline dose in childhood acute lymphoblastic leukemia: issues of early survival versus late cardiotoxicity. J Clin Oncol 1997; 15:61-8. [PMID: 8996125 DOI: 10.1200/jco.1997.15.1.61] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Late abnormalities of left ventricular (LV) performance occur in most survivors of childhood acute lymphoblastic leukemia (ALL) treated with moderate anthracycline doses. We studied the prevalence of late cardiotoxicity in patients treated with lower anthracycline doses and related this to survival. PATIENTS AND METHODS Echocardiograms were performed in 50 normal children and 120 relapse-free ALL survivors 6.2 +/- 2.0 years after the end of cumulative daunorubicin doses of 90 mg/m2 (n = 40), 180 mg/m2 (n = 40), or 270 mg/m2 (n = 40) on UKALL X pilot (1982 to 1984) or UKALL X (1985 to 1989) protocols. Age at treatment onset was 4.7 +/- 2.8 years. Cardiac abnormalities were reviewed in light of the UKALL X 5-year disease-free survival rates of 57% (95% confidence interval [CI], 51% to 63%), 61% to 62% (95% CI, 56% to 68%), and 71% (95% CI, 66% to 76%) for the groups that received 90, 180, and 270 mg/m2 of daunorubicin, respectively. RESULTS ALL survivors had reduced LV fractional shortening (FS) compared with normal (32.3% +/- 4.4% v 35.9% +/- 4.2%, P < .005), which was accounted for by increased LV end-systolic stress (49.4 +/- 13.5 v 42.2 +/- 9.1 g/cm2, P < .001), whereas LV contractility independent of loading conditions was normal for the group as a whole. Of 27 patients (23%) with cardiac abnormalities, 25 (21%) had increased end-systolic stress, whereas only two (2%) had reduced contractility. The proportion with cardiac abnormality was similar in the three dose groups. Anthracycline dose, age at treatment, sex, follow-up duration, growth hormone, pubertal status, hemoglobin level, and total WBC count at presentation were not predictive of increased LV end-systolic stress. CONCLUSION There was a reduced incidence and severity of cardiac abnormalities with the lower anthracycline dose protocols (90 to 270 mg/m2) studied compared with previous reports in which subjects had received moderate anthracycline doses (approximately 300 to 550 mg/m2). Cumulative anthracycline dose within the range 90 to 270 mg/m2 did not relate to cardiac abnormalities. This suggests that there may be no safe anthracycline dose to avoid late cardiotoxicity, but reinforces the use of the protocol that affords best survival within the dose range studied.
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