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Schmidt W. Ultraschall bei Vaskulitiden. AKTUEL RHEUMATOL 2017. [DOI: 10.1055/s-0042-105953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
ZusammenfassungMittels Ultraschall lässt sich eine pathognomonische Gefäßwandschwellung bei Vaskulitiden an Temporalarterien und an extrakraniellen Arterien nachweisen. Die Sonografie ist wichtiger Bestandteil in der Diagnostik der Arteriitis temporalis, der Riesenzellarteriitis großer Gefäße und der Takayasu Arteriitis geworden. Durch „Fast Track Clinics“ in denen gleichzeitig fachärztliche klinische Untersuchung und Sonografie mindestens von Temporal- und Axillararterien angeboten wird, kann die Inzidenz von Erblindungen reduziert werden.
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Naumann U, Moll A, Schleehauf D, Lutz T, Schmidt W, Jaeger H, Funke B, Witte V. Similar efficacy and tolerability of raltegravir-based antiretroviral therapy in HIV-infected patients, irrespective of age group, burden of comorbidities and concomitant medication: Real-life analysis of the German 'WIP' cohort. Int J STD AIDS 2017; 28:893-901. [PMID: 28385065 PMCID: PMC5513442 DOI: 10.1177/0956462416679550] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/01/2016] [Indexed: 11/18/2022]
Abstract
Only limited efficacy and tolerability data on raltegravir (RAL) use are currently available. Study objectives were to describe the efficacy and tolerability profile of RAL-based antiretroviral therapy (ART) in routine clinical practice in Germany. The WIP study (WIP = "Wirksamkeit von Isentress unter Praxisbedingungen", Efficacy of Isentress under routine clinical conditions) was a prospective, multi-centre cohort study in Germany. Human immunodeficiency virus (HIV)-infected patients aged ≥ 18 years in whom combinational ART with RAL 400 mg BID was indicated were enrolled. The primary endpoint was virologic response (HIV-RNA <50 copies/mL; non-completion equals failure) after 48 weeks. Of 451 patients, 85.1% (n = 384) were still receiving RAL at week 48. At baseline (BL), the prevalence of concomitant diseases was higher in patients of the age group ≥50 years (94.2% vs. 75.7%) as well as concomitant medications (74.8 % vs. 55.4%). Virologic response at week 48 was 74.7% (overall), 75.0% (naïve at BL), 81.5% (suppressed at BL), 47.1% (interrupted previous treatment at BL) and 64.9% (failing at BL), without significant differences by age group. A significant correlation of achievement of HIV-RNA <50 copies/mL was seen with treatment status at BL (p = 0.004). In addition, 77.3 % of the patients with a CD4 cell count >200 cells/µL at BL achieved HIV-RNA <50 copies/mL (p = 0.029). RAL was well tolerated with 80 adverse events (AEs) in 49 patients (10.9%) and 8 serious AEs (SAEs) in 6 patients (1.3%) reported to be drug related. A total of 22 patients (4.9%) discontinued treatment due to AEs. The WIP study shows that the previously reported efficacy and safety profile of RAL can be achieved in a population with multiple comorbidities and comedications, with no major difference observed in ageing patients (≥50 years) vs. younger patients. RAL is therefore an attractive treatment option in routine medical care in Germany.
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Andersson M, Kolodziej B, Andersson RE, Andersson M, Eriksson T, Ramsing A, Westman L, Björkman J, Håkansson HO, Lundström T, Björkman H, Johansson P, Hjert O, Edin R, Ekström A, Wenander C, Wallon C, Andersson P, Frisk J, Arvidsson B, Lantz R, Wallin G, Wickberg Å, Stenberg E, Erixon C, Schmidt W, Räntfors J, Göthberg G, Styrud J, Elias K, Boström L, Kretschmar G, Jonsson M, Brav C, Nilsson I, Kamran F, Hammarqvist F, Rutqvist J, Almström M, Hedberg M, Lindh V, Rosemar A, Wangberg H, Gustafsson J, Neovius G, Juhlin C, Christofferson R, Månsson C, Zittel T, Fagerström N. Randomized clinical trial of Appendicitis Inflammatory Response score-based management of patients with suspected appendicitis. Br J Surg 2017; 104:1451-1461. [PMID: 28730753 DOI: 10.1002/bjs.10637] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 05/23/2017] [Accepted: 05/31/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND The role of imaging in the diagnosis of appendicitis is controversial. This prospective interventional study and nested randomized trial analysed the impact of implementing a risk stratification algorithm based on the Appendicitis Inflammatory Response (AIR) score, and compared routine imaging with selective imaging after clinical reassessment. METHOD Patients presenting with suspicion of appendicitis between September 2009 and January 2012 from age 10 years were included at 21 emergency surgical centres and from age 5 years at three university paediatric centres. Registration of clinical characteristics, treatments and outcomes started during the baseline period. The AIR score-based algorithm was implemented during the intervention period. Intermediate-risk patients were randomized to routine imaging or selective imaging after clinical reassessment. RESULTS The baseline period included 1152 patients, and the intervention period 2639, of whom 1068 intermediate-risk patients were randomized. In low-risk patients, use of the AIR score-based algorithm resulted in less imaging (19·2 versus 34·5 per cent; P < 0·001), fewer admissions (29·5 versus 42·8 per cent; P < 0·001), and fewer negative explorations (1·6 versus 3·2 per cent; P = 0·030) and operations for non-perforated appendicitis (6·8 versus 9·7 per cent; P = 0·034). Intermediate-risk patients randomized to the imaging and observation groups had the same proportion of negative appendicectomies (6·4 versus 6·7 per cent respectively; P = 0·884), number of admissions, number of perforations and length of hospital stay, but routine imaging was associated with an increased proportion of patients treated for appendicitis (53·4 versus 46·3 per cent; P = 0·020). CONCLUSION AIR score-based risk classification can safely reduce the use of diagnostic imaging and hospital admissions in patients with suspicion of appendicitis. Registration number: NCT00971438 ( http://www.clinicaltrials.gov).
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Schäfer H, Stahn R, Schmidt W. Lösangsmitteleffekte auf die Fluoreszenz-Quantenausbeuten von Thionin und Methylenblau. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-1979-260110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Schäfer H, Schmidt W. Ligandeneffekte auf die Reaktionen von Triplett-Methylenblau and Triplett-Thionin mit Fe II. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-1979-260106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Schäfer H, Schmidt W. Lösungsmitteleffekte auf die Photoreaktionen von Methylenblau und Thionin mit Fe II. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-1979-260113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Wintermantel J, Wachsmuth N, Schmidt W. Doping Cases among Elite Athletes from 2000 to 2013. DEUTSCHE ZEITSCHRIFT FÜR SPORTMEDIZIN 2016. [DOI: 10.5960/dzsm.2016.258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Khalil AA, Hohenhaus M, Kunze C, Schmidt W, Brunecker P, Villringer K, Merboldt KD, Frahm J, Fiebach JB. Sensitivity of Diffusion-Weighted STEAM MRI and EPI-DWI to Infratentorial Ischemic Stroke. PLoS One 2016; 11:e0161416. [PMID: 27529697 PMCID: PMC4987060 DOI: 10.1371/journal.pone.0161416] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 08/01/2016] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES To assess the sensitivity of stimulated echo acquisition mode diffusion weighted imaging (STEAM-DWI) to ischemic stroke in comparison to echo-planar imaging diffusion weighted imaging (EPI-DWI) in the infratentorial compartment. METHODS Fifty-seven patients presenting with clinical features of infratentorial stroke underwent STEAM-DWI, high-resolution EPI-DWI (HR-DWI, 2.5 mm slice thickness) and low-resolution EPI-DWI (LR-DWI, 5 mm slice thickness). Four readers assessed the presence of ischemic lesions and artifacts. Agreement between sequences and interobserver agreement on the presence of ischemia were calculated. The sensitivities of the DWI sequences were calculated in 45 patients with a confirmed diagnosis of infratentorial stroke. RESULTS Median time from symptom onset to imaging was 24 hours. STEAM-DWI agreed with LR-DWI in 89.5% of cases (kappa = 0.72, p<0.0001) and with HR-DWI in 89.5% of cases (kappa = 0.68, p<0.0001). STEAM-DWI showed fewer intraparenchymal artifacts (1/57) than HR-DWI (44/57) and LR-DWI (41/57). Ischemia was visible in 87% of cases for LR-DWI, 93% of cases for HR-DWI, and 89% of cases for STEAM-DWI. Interobserver agreement was good for STEAM-DWI (kappa = 0.62, p<0.0001). CONCLUSIONS Compared to the best currently available MR sequence for detecting ischemia (HR-DWI), STEAM-DWI shows fewer artifacts and a similar sensitivity to infratentorial stroke.
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Glimm AM, Ohrndorf S, Fischer I, Strunk J, Schmidt W, Hartung W, Sattler H, Kellner H, Schmittat G, Burmester GR, Backhaus M. OP0124 Imaging Remission by Musculoskeletal Ultrasound Leads To A Better Functional Outcome – Results of The US Impera Study - Us 7-Score Implementation Study in Early Rheumatoid Arthritis. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.5892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Ryan BJ, Goodrich JA, Schmidt W, Kane LA, Byrnes WC. Ten Days of Intermittent, Low-dose Carbon Monoxide Inhalation does not Significantly Alter Hemoglobin Mass, Aerobic Performance Predictors, or Peak-power Exercise Tolerance. Int J Sports Med 2016; 37:884-9. [PMID: 27410770 DOI: 10.1055/s-0042-108197] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Carbon monoxide (CO) rebreathing procedures are used to assess hemoglobin mass (Hbmass) but recent evidence suggests that CO is a signaling molecule that may alter physiological functions. We examined the effects of 10 days of intermittent, low-dose CO inhalation on Hbmass, aerobic performance predictors, and peak-power exercise tolerance. 18 recreationally-active men were randomized to either CO or placebo inhalation groups in a single-blind, pre-post parallel-groups trial. Primary outcomes were assessed before and after an intervention period during which subjects inhaled a bolus of 1.2 ml kg(-1) CO or placebo (room air) for 30 s, once per day on 10 days over a 12-day period. Cycling tests were performed >16 h following CO inhalation to exclude acute effects of CO exposure. CO inhalation elevated carboxyhemoglobin by 4.4±0.4% (mean±SD) following each exposure. Compared to placebo, chronic CO inhalation did not significantly alter Hbmass (p=0.99), peak oxygen uptake (p=0.59), peak power output (p=0.10), submaximal oxygen uptake (p=0.91), submaximal RER (p=0.22), lactate threshold (p=0.65), or peak-power exercise tolerance (p=0.60). In conclusion, our data support the ability to perform repeated measurements of Hbmass using CO rebreathing over a 12-day period without altering physiological responses.
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Adinolfi A, Filippou G, Scirè C, Damjanov N, Carrara G, Picerno V, Toscano C, Bruyn G, D'Agostino M, Delle Sedie A, Filippucci E, Gutierrez M, Micu M, Moller I, Naredo E, Pascal Z, Pineda C, Porta F, Schmidt W, Terslev L, Vlad V, Zufferey P, Frediani B, Iagnocco A. FRI0517 The Omeract Ultrasonographic Criteria for Elementary Lesions in Calcium Pyrophosphate Deposition Disease: Results of A Delphi Process by Ultrasound Working Group. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.5406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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White S, Schmidt W, Sahanggamu D, Fatmaningrum D, van Liere M, Curtis V. Can gossip change nutrition behaviour? Results of a mass media and community-based intervention trial in East Java, Indonesia. Trop Med Int Health 2016; 21:348-64. [PMID: 26701153 DOI: 10.1111/tmi.12660] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE It is unclear how best to go about improving child feeding practices. We studied the effect of a novel behaviour change intervention, Gerakan Rumpi Sehat (the Healthy Gossip Movement), on infant and young child feeding practices in peri-urban Indonesia. METHODS The pilot intervention was designed based on the principles of a new behaviour change theory, Behaviour Centred Design (BCD). It avoided educational messaging in favour of employing emotional drivers of behaviour change, such as affiliation, nurture and disgust and used television commercials, community activations and house-to-house visits as delivery channels. The evaluation took the form of a 2-arm cluster randomised trial with a non-randomised control arm. One intervention arm received TV only, while the other received TV plus community activations. The intervention components were delivered over a 3-month period in 12 villages in each arm, each containing an average of 1300 households. There were two primary outcomes: dietary diversity of complementary food and the provision of unhealthy snacks to children aged 6-24 months. RESULTS Dietary diversity scores increased by 0.8 points in the arm exposed to TV adverts only (95% CI: 0.4-1.2) and a further 0.2 points in the arm that received both intervention components (95% CI: 0.6-1.4). In both intervention arms, there were increases in the frequency of vegetable and fruit intake. We found inconsistent evidence of an effect on unhealthy snacking. CONCLUSION The study suggests that novel theory-driven approaches which employ emotional motivators are capable of having an effect on improving dietary diversity and the regularity of vegetable and fruit intake among children aged 6-24 months. Mass media can have a measurable effect on nutrition-related behaviour, but these effects are likely to be enhanced through complementary community activations. Changing several behaviours at once remains a challenge.
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Siewert S, Sämann M, Schmidt W, Stiehm M, Falke K, Grabow N, Guthoff R, Schmitz KP. Gekoppelte Analyse der Fluid-Struktur-Interaktion eines mikromechanischen Ventils für Glaukomdrainageimplantate. Klin Monbl Augenheilkd 2015; 232:1374-80. [DOI: 10.1055/s-0041-107940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kane LA, Ryan BJ, Schmidt W, Byrnes WC. Acute, Low-dose CO Inhalation does not Alter Energy Expenditure during Submaximal Exercise. Int J Sports Med 2015; 37:19-24. [PMID: 26509382 DOI: 10.1055/s-0035-1554641] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Carbon monoxide, a gas known most widely for its toxic effects at high doses, is receiving increased attention for its role as a physiological signaling molecule and potential therapeutic agent when administered in low doses. We sought to quantify any changes to oxygen consumption and energy expenditure during submaximal exercise after low-dose CO inhalation. 9 active individuals completed 4 graded submaximal exercise tests, with each test occurring during a separate visit. For their first exercise test, subjects inhaled CO or room air (1.2 mL·kg(-1) body mass) in a randomized, subject-blind fashion. A second test was repeated 24 h later when the inhaled gas should have cleared the system. Subjects repeated study procedures with the alternate dose after a washout period of at least 2 days. Low-dose CO administration did not affect oxygen consumption or energy expenditure during submaximal exercise immediately or 24 h following its administration. Increases in heart rate, blood [lactate], and perceived exertion were observed following acute CO inhalation but these effects were absent after 24 h. The results of this study suggest that low-dose CO administration does not influence the energetics of submaximal exercise, but it acutely increases the relative intensity associated with absolute workloads below the lactate threshold.
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Naumann R, Schmidt W. Inverse Pulspolarographie am hängenden Quecksilbertropfen. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/bf00498527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Iagnocco A, Terslev L, Backhaus M, Balint P, Bruyn GAW, Damjanov N, Filippucci E, Hammer HB, Jousse-Joulin S, Kane D, Koski JM, Mandl P, Möller I, Peetrons P, Schmidt W, Szkudlarek M, Vojinovic J, Wakefield RJ, Hofer M, D'Agostino MA, Naredo E. Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses. RMD Open 2015; 1:e000139. [PMID: 26535148 PMCID: PMC4623365 DOI: 10.1136/rmdopen-2015-000139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 08/06/2015] [Accepted: 08/22/2015] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVE To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses. METHODS A Delphi-based procedure with 24 recommendations covering five main areas (Duration and place of the course; Faculty members; Content of the course; Evaluation of the teaching skills; TTT competency assessment) was distributed among a group of experts involved in MSUS teaching, in addition to an advisory educational expert being present. Consensus for each recommendation was considered achieved when the percentage of agreement was >75%. RESULTS 21 of 24 invited participants responded to the first Delphi questionnaire (88% response rate). All 21 participants also responded to the second round. Agreement on 19 statements was obtained after two rounds. CONCLUSIONS This project has led to the development of guidelines for the conduct, content and format of teaching at the EULAR MSUS TTT Courses that are organised annually, with the aim of training future teachers of EULAR MSUS Courses, EULAR Endorsed MSUS Courses, as well as national and local MSUS Courses. The presented work gives indications on how to homogenise the teaching at the MSUS TTT Courses, thus resolving current discrepancies in the field.
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Stahnke T, Siewert S, Walther E, Schmidt W, Stachs O, Schmitz KP, Guthoff RF. Adopting oculopressure tonometry as a transient in vivo rabbit glaucoma model. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2015. [DOI: 10.1515/cdbme-2015-0033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Glaucoma represents a group of eye disorders partly related to raised intraocular pressure (IOP) leading to progressive optic nerve damage resulting in impaired vision and possibly blindness. To assess the suitability of new IOP lowering therapeutic strategies, such as the implantation of glaucoma drainage devices, appropriate animal models have to be used. Currently, a number of rodent glaucoma models are available [1], however, especially for surgical interventions rodent eyes are too small. Rabbits are much more suitable with respect to dimension. Unfortunately, rabbit glaucoma model systems described in literature are difficult to reproduce or fail totally, associated with a high level of discomfort and pain for treated animals. Therefore, development of an
in vivo
rabbit glaucoma model is one of the most important goals in glaucoma research. Here, we describe the adaptation of the oculopressure tonometry, an existing method to quantify the outflow of aqueous humor in humans, to generate a transient glaucoma model in rabbits. The existing suction-cup oculopressor (SCOP) is extended with newly designed suction-cups, which are adjusted to the anatomy of the rabbit eye. The modification of the oculopressure tonometry method facilitates an increase in IOP over a time frame of 9 minutes by vacuum induced deformation of the rabbit eye. This method can be used to test functionality of fistulating glaucoma surgeries or implanted drainage devices in a long term follow-up without any side effects and suffering of the animals.
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Matthies JB, Kurzhals A, Schmidt W, Atamna A, Andresen R, Schmitz KP, Grabow N. Test setup for characterizing the efficacy of embolic protection devices. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2015. [DOI: 10.1515/cdbme-2015-0109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Systems for embolic protection are applied during the dilatation and the implantation of stents in the carotid artery. They are used to avoid downstream drift of arterial plaque particles which may be released during the intervention. Such particulate debris increases the risk of stroke when reaching and occluding even minor cranial vessels. Embolic protection devices (EPD) are intended to collect such particles during intervention and to finally remove them.
A test setup was developed in order to assess the effi-cacy of commercially available EPDs. The setup considers the introduction of relevant particles, as well as typical anatomic conditions. The EPDs could be tested using curved and ovalized vessel types to simulate stressed vessel conditions. Furthermore, a method for counting the particles was established to quantify collected particles in the EPD, the leaked particles and those which were left behind in the vessel.
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Boeck M, Kamke F, Grabow N, Schmidt W. Investigation of the dynamic diameter deformation of vascular stents during fatigue testing with radial loading. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2015. [DOI: 10.1515/cdbme-2015-0124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Endovascular stents are exposed to cyclic loads resulting from daily activity and pulsatile arterial blood pressure. DIN EN ISO 25539-2 and FDA guideline 1545 recommend durability testing, exposing stents to physiological cyclic loads for a 10 year equivalent. For accelerated testing, the simulated deformation has to be comparable to physiological in-vivo deformation. A new test setup is presented to determine diameter deformation of vascular stents during fatigue testing with radial loading.
Methods
The new setup allows the investigation of stents (n = 1–10) up to a length of 200 mm using a CCD line camera independent from special configurations. For demonstration, the radial deformation of two peripheral stents (stent 1: 8.0×40 mm, stent 2: 4.5×40 mm) and coronary stents (stent 3: 2.5×22 mm, stent 4: 4.0×40 mm) is determined as a function of the longitudinal measuring position. The stents are implanted in polyurethane tubes and exposed to physiologically relevant pressure at test frequencies 100 Hz.
Results
In addition to the verification of test frequencies for fatigue testing the setup can also be used for the investigation of radial deformation performance. The results show that radial deformation may vary along the stent length. Larger radial deformation was detected at the middle of the stent. For stent 1 a maximum deformation of 0.21 ± 0.07 mm (± 2.65 %) was measured at 50 ± 40 mmHg, 90 Hz. It was also measured that the radial deformation is dependent on stent design, geometric dimension and external loading.
Conclusion
The new setup allows for test frequency verification for accelerated fatigue testing with radial loading. It is also suitable for more detailed investigation of the radial deformation performance of stents along their longitudinal axis. This is necessary for a better understanding of potential mechanical failure especially in the case of long or overlapping stents.
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Koski JM, Kamel A, Waris P, Waris V, Tarkiainen I, Karvanen E, Szkudlarek M, Aydin SZ, Alasaarela E, Schmidt W, De Miguel E, Mandl P, Filippucci E, Ziswiler H, Terslev L, Áts K, Kurucz R, Naredo E, Balint P, Iagnocco A, Lepojärvi S, Elseoud A, Fouda M, Saarakkala S. Atlas-based knee osteophyte assessment with ultrasonography and radiography: relationship to arthroscopic degeneration of articular cartilage. Scand J Rheumatol 2015; 45:158-64. [DOI: 10.3109/03009742.2015.1055797] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Petersen U, Schmidt W. NUEVOS ESTÍMULOS PARA EL DEPORTE ESCOLAR. EDUCACION FISICA Y DEPORTE 2015. [DOI: 10.17533/udea.efyd.23027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
La educación física y el deporte se desarrollan de dos maneras diferentes en la escuela. Por un lado, el deporte es el objeto de una materia de enseñanza obligatoria para todos los alumnos. Pero, junto a esto el deporte también se lleva a cabo y se realiza independientemente de la educación física obligatoria y siempre que la escuela permita la práctica libre del deporte, respectivamente, no prohíbe las actividades de movimiento de los alumnos. Los nuevos estímulos para el deporte pertenecen a esta segunda área del deporte escolar. Ellos no representan exigencias obligatorias, sino que los alumnos por decisión propia y libremente, los aceptan o los rechazan.
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Tseng JC, Schmidt W, Sager U, Däuber E, Pommerin A, Weidenthaler C. Microstructure analysis of complex CuO/ZnO@carbon adsorbers: what are the limits of powder diffraction methods? Phys Chem Chem Phys 2015; 17:12282-91. [PMID: 25892653 DOI: 10.1039/c5cp01135c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Activate carbon impregnated with a mixture of copper oxide and zinc oxide performs well as active adsorber for NO2 removal in automotive cabin air filters. The oxide-loaded activated carbon exhibits superior long-term stability in comparison to pure activated carbon as has been shown in previous studies. The carbon material was loaded only with 2.5 wt% of each metal oxide. Characterization of the oxide nanoparticles within the pores of the activated carbon is difficult because of the rather low concentration of the oxides. Therefore, a systematic study was performed to evaluate the limits of line profile analysis of X-ray powder diffraction patterns. The method allows evaluation of crystalline domain size distributions, crystal defect concentrations and twinning probabilities of nanoscopic materials. Here, the analysis is hampered by the presence of several phases including more or less amorphous carbon. By using physical mixtures of defined copper oxide and zinc oxide particles with activated carbon, potential errors and limits could be identified. The contribution of the activated carbon to the scattering curve was modeled with a convolution of an exponential decay curve, a Chebyshev polynomial, and two Lorentzian peaks. With this approach, domain size distributions can be calculated that are shifted only by about 0.5-1.0 nm for very low loadings (≤4 wt%). Oxide loadings of 4 wt% and 5 wt% allow very reliable analyses from diffraction patterns measured in Bragg-Brentano and Debye-Scherrer geometry, respectively. For the real adsorber material, mean domain sizes have been calculated to be 2.8 nm and 2.4 nm before and after the NO2 removal tests.
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Rietsch S, Schmidt W. MRT-Grundlagen. ROFO-FORTSCHR RONTG 2015. [DOI: 10.1055/s-0035-1551505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Wissgott C, Schmidt W, Andresen R. Experimentelle mechanische Eigenschaften und erste klinische Ergebnisse eines neuen doppelschichtigen Carotisstents. ROFO-FORTSCHR RONTG 2015. [DOI: 10.1055/s-0035-1551092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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50
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Kutzner D, Schmidt W. „Gedanken sehen“ – Funktionelle Bildgebung in der Kernspintomografie. ROFO-FORTSCHR RONTG 2015. [DOI: 10.1055/s-0035-1551496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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