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Vogel R, Heinzelmann F, Büchler P, Mück B. [Roboticassisted incisional hernia surgery-Retromuscular techniques]. CHIRURGIE (HEIDELBERG, GERMANY) 2024; 95:27-33. [PMID: 38051317 DOI: 10.1007/s00104-023-01998-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/02/2023] [Indexed: 12/07/2023]
Abstract
The trend to minimally invasive surgery has also made its way into the surgical treatment of incisional hernias. Unlike other areas of visceral surgery, recent years have seen a resurgence of open sublay repair in incisional hernia procedures, primarily due to the recognition of the retromuscular layer as the optimal mesh placement site. Additionally, with the growing availability of robotic systems in visceral surgery, these procedures are increasingly being offered in the form of minimally invasive procedures. These methods can be categorized based on the access routes: robotic-assisted transperitoneal procedures (e.g., r‑Rives, r‑TARUP, r‑TAR) and total extraperitoneal hernia repair (e.g., r‑eTEP, r‑eTAR). Notably, the introduction of transversus abdominis muscle release enables the robotic-assisted treatment of larger and more complex hernia cases with complete fascial closure. With respect to the comparison with open surgery required in retromuscular hernia treatment, the currently available literature on incisional hernia repair seems to show initial advantages of robotic-assisted surgery in the perioperative course. New technologies create new possibilities. In the context of surgical training the use of surgical robot systems with double consoles opens up completely new perspectives. Furthermore, the robot enables the implementation of models of artificial intelligence and augmented reality and could therefore open up novel dimensions in surgery.
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Amstutz C, Behr J, Krebs S, Haeberlin A, Vogel R, Zurbuchen A, Burger J. Design of percutaneous transluminal coronary angioplasty balloon catheters. Biomed Eng Online 2023; 22:94. [PMID: 37742021 PMCID: PMC10517552 DOI: 10.1186/s12938-023-01155-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/15/2023] [Indexed: 09/25/2023] Open
Abstract
BACKGROUND Eight commercially available percutaneous transluminal coronary angioplasty (PTCA), including semi-compliant and non-compliant balloons, have been assessed in detail on their tip, balloon, shaft, RX-Port, and hypotube design. Important performance characteristics such as tip deformation, balloon elongation, and deflation rate have been quantified. METHODS Five catheters of each model were evaluated during various tests. The robustness of the tips was evaluated through compression, measuring any occurrence of damage. The longitudinal growth of the balloons was recorded during inflation up to Rated Burst Pressure (RBP). The forces required to move the catheter forward and retract it into the guide catheter were measured in a simulated use test setup. The deflation behavior was studied by measuring extracted contrast media over time. Furthermore, balloon compliance and catheter dimensions were investigated. RESULTS The outer dimensions of the catheter were found to be smallest at the hypotube (0.59-0.69 mm) and highest at the balloon, respectively, the crossing profile (0.9-1.2 mm). The tip diameter increased after compression by 1.7-22%. Cross-sections of the folded balloons revealed a tri- and two-fold, respectively. The measured balloon elongation ranged from 0.6 to 2.0 mm. After the inflation of the balloon, an increase in friction between the guide wire and the catheter was observed on four catheters. A maximum increase of 0.12 N to 1.07 N was found. Cross-sections of the RX-Port revealed a semicircular-shaped inflation lumen and a circular guide wire lumen. The measured deflation rate ranged from 0.004 to 0.013 µL/s, resulting in an estimated balloon deflation time of 10.2-28.1 s. CONCLUSION This study provides valuable insights into the design characteristics of RX PTCA balloon catheters, which can contribute to facilitating the development of improved catheter designs and enhancing clinical outcomes. Distinctions between SC and NC catheters, such as balloon performance and dimensions, are evident. It is important to note that no single catheter excels in all aspects, as each possesses unique strengths. Therefore, it is essential to consider individual intervention requirements when selecting a catheter. The research also identifies specific catheter weaknesses, such as reduced wall thickness, fringes at the tip, and reduced performance characteristics.
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Werum V, Ehrmann M, Vogel R, Hilgarth M. Comparative genome analysis, predicted lifestyle and antimicrobial strategies of Lactococcus carnosus and Lactococcus paracarnosus isolated from meat. Microbiol Res 2022; 258:126982. [DOI: 10.1016/j.micres.2022.126982] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/04/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022]
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Gasser B, Vogel R. Older orienteers perform better–is experience key? Sci Sports 2021. [DOI: 10.1016/j.scispo.2020.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Caputo F, Vogel R, Savage J, Vella G, Law A, Della Camera G, Hannon G, Peacock B, Mehn D, Ponti J, Geiss O, Aubert D, Prina-Mello A, Calzolai L. Measuring particle size distribution and mass concentration of nanoplastics and microplastics: addressing some analytical challenges in the sub-micron size range. J Colloid Interface Sci 2021; 588:401-417. [PMID: 33422789 DOI: 10.1016/j.jcis.2020.12.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/13/2022]
Abstract
HYPOTHESIS The implementation of the proposal from the European Chemical Agency (ECHA) to restrict the use of nanoplastics (NP) and microplastics (MP) in consumer products will require reliable methods to perform size and mass-based concentration measurements. Analytical challenges arise at the nanometre to micrometre interface, e.g., 800 nm-10 µm, where techniques applicable at the nanometre scale reach their upper limit of applicability and approaches applicable at the micrometre scale must be pushed to their lower limits of detection. EXPERIMENTS Herein, we compared the performances of nine analytical techniques by measuring the particle size distribution and mass-based concentration of polystyrene mixtures containing both nano and microparticles, with the educational aim to underline applicability and limitations of each technique. FINDINGS Light scattering-based measurements do not have the resolution to distinguish multiple populations in polydisperse samples. Nanoparticle tracking analysis (NTA), nano-flowcytometry (nFCM) and asymmetric flow field flow fractionation hyphenated with multiangle light scattering (AF4-MALS) cannot measure particles in the micrometre range. Static light scattering (SLS) is not able to accurately detect particles below 200 nm, and similarly to transmission electron microscopy (TEM) and flow cytometry (FCM), is not suitable for accurate mass-based concentration measurements. Alternatives for high-resolution sizing and concentration measurements in the size range between 60 nm and 5 µm are tunable resistive pulse sensing (TRPS) and centrifugal liquid sedimentation (CLS), that can bridge the gap between the nanometre and micrometre range.
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Brown NA, Spielmann H, Bechter R, Flint OP, Freeman SJ, Jelínek RJ, Koch E, Nau H, Newall DR, Palmer AK, Renault JY, Repetto MF, Vogel R, Wiger R. Screening Chemicals for Reproductive Toxicity: The Current Alternatives. Altern Lab Anim 2020. [DOI: 10.1177/026119299502300615] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Orlando A, Cordero J, Carrick MM, Tanner AH, Banton K, Vogel R, Lieser M, Acuna D, Bar-Or D. Comparing complications of small-bore chest tubes to large-bore chest tubes in the setting of delayed hemothorax: a retrospective multicenter cohort study. Scand J Trauma Resusc Emerg Med 2020; 28:56. [PMID: 32571367 PMCID: PMC7310264 DOI: 10.1186/s13049-020-00754-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/12/2020] [Indexed: 11/10/2022] Open
Abstract
Background Previous studies have provided initial data suggesting that small-bore (SB, ≤ 14Fr) chest tubes have the same efficacy as large-bore (LB, > 14 Fr) chest tubes for acute hemothorax (HTX), but data continue to be lacking in the setting of delayed HTX. This study compared complications of SB chest tubes to LB tubes in patients with delayed HTX. Methods This was a retrospective observational study across 7.5 yrs. at 6 Level 1 trauma centers. Patients were included if 1) diagnosed with a HTX or > 1 rib fracture with bloody effusion from chest tube; 2) initial chest tube placed ≥36 h of hospital admission. Patients were excluded for hemopneumothoraces. The primary endpoint was having at least one of the following chest tube complications: tube replacement, VATS, tube falling out, tube clogging, pneumonia, retained HTX, pleural empyema. Secondary outcomes included chest tube output volume and drainage rate. Dependent/independent and parametric/non-parametric analyses were used to assess primary and secondary outcomes. Results There were 160 SB patients (191 tubes) and 60 LB patients (72 tubes). Both comparison groups were similar in multiple demographic, injury, clinical features. The median (IQR) tube size for each group was as follows: SB [12 Fr (12–14)] and LB [32 Fr (28–32)]. The risk of having at least one chest tube complication was similar for LB and SB chest tubes (14% vs. 18%, p = 0.42). LB tubes had significantly larger risk of VATS, while SB tubes had significantly higher risk of pneumonia. SB tubes had significantly slower least squares (LS) mean initial output drainage rate compared to LB tubes (52.2 vs. 213.4 mL/hour, p < 0.001), but a non-parametric analysis suggested no significant difference in median drainage rates between groups 39.7 [23.5–242.0] mL/hr. vs. 38.6 [27.5–53.8], p = 0.81. LB and SB groups had similar initial output volume (738.0 mL vs. 810.9, p = 0.59). Conclusions There was no clearly superior chest tube diameter size; both chest tube sizes demonstrated risks and benefits. Clinicians must be aware of these potential tradeoffs when deciding on the diameter of chest tube for the treatment of delayed HTXs.
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Wilent WB, Ney JP, Balzer J, Donohue ML, Gertsch JH, Holdefer R, Jahangiri FR, Overzet K, Shils J, Vogel R. Letter to the Editor. Intraoperative neurophysiological monitoring and ACDF. J Neurosurg Spine 2019; 32:152-153. [PMID: 31585415 DOI: 10.3171/2019.6.spine19641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Johnson P, Mur T, Vogel R, Roehm PC. Percutaneous Threshold of Facial Nerve Stimulation Predicts Facial Canal Dehiscence. Neurodiagn J 2019; 59:91-103. [PMID: 31210607 DOI: 10.1080/21646821.2019.1614420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Iatrogenic facial nerve (FN) injury is one of the most feared complications of otologic surgery. Dehiscence of the bony covering of the FN within the temporal bone increases FN vulnerability to accidental injury. High-resolution computed tomography (HRCT) of the temporal bone is used preoperatively to assess middle ear and mastoid anatomy; however, it is unreliable for detecting facial canal dehiscence. In this study, our aim was to determine if preoperative percutaneous FN stimulation could predict middle ear facial canal dehiscence. Between January 2015 and February 2017, we performed preoperative HRCT and percutaneous FN stimulation on adult patients who underwent otologic surgery at our institution. Stimulation was performed with a monopolar probe placed on the skin over the stylomastoid foramen. Electrical stimuli ranged from 0 to 40 milliamperes (mA). Recordings were made from ipsilateral facial muscles. Dependent variables included threshold to compound muscle action potential (CMAP), threshold to maximum amplitude of CMAP, and maximum amplitude of CMAP for each muscle. A retrospective chart review was performed. Seventy patients met inclusion criteria. Of the 24 with an intraoperatively confirmed dehiscence, 10 were identified preoperatively by the attending surgeon on HRCT. Averages of the lowest recorded threshold to CMAP (5.1mA v. 9.1mA), and an average of the threshold to CMAP (8.9 mA. 11.8 mA) of dehiscent versus non-dehiscent nerves were significantly different (p < .05). In conclusion, percutaneous FN stimulation is a simple and cost-effective tool that can give the surgeon important preoperative information about FN anatomy.
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Vogel R. Infection Prevention and Control's Role in the Design and Construction of a new Ambulatory Care Center. Lessons Learned. Am J Infect Control 2019. [DOI: 10.1016/j.ajic.2019.04.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Spielmann H, Vogel R. REACH Testing Requirements Must Not be Driven by Reproductive Toxicity Testing in Animals. Altern Lab Anim 2019; 34:365-6. [PMID: 16945004 DOI: 10.1177/026119290603400405] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hunziker L, Radovanovic D, Jeger R, Pedrazzini G, Cuculi F, Urban P, Erne P, Rickli H, Pilgrim T, Hess F, Simon R, Hangartner P, Hufschmid U, Hornig B, Altwegg L, Trummler S, Windecker S, Rueff T, Loretan P, Roethlisberger C, Evéquoz D, Mang G, Ryser D, Müller P, Jecker R, Kistler W, Hongler T, Stäuble S, Freiwald G, Schmid H, Stauffer J, Cook S, Bietenhard K, Roffi M, Wojtyna W, Schönenberger R, Simonin C, Waldburger R, Schmidli M, Federspiel B, Weiss E, Marty H, Weber K, Zender H, Poepping I, Hugi A, Koltai E, Iglesias J, Erne P, Heimes T, Jordan B, Pagnamenta A, Feraud P, Beretta E, Stettler C, Repond F, Widmer F, Heimgartner C, Polikar R, Bassetti S, Iselin H, Giger M, Egger P, Kaeslin T, Fischer A, Herren T, Eichhorn P, Neumeier C, Flury G, Girod G, Vogel R, Niggli B, Yoon S, Nossen J, Stoller U, Veragut U, Bächli E, Weber A, Schmidt D, Hellermann J, Eriksson U, Fischer T, Peter M, Gasser S, Fatio R, Vogt M, Ramsay D, Wyss C, Bertel O, Maggiorini M, Eberli F, Christen S. Twenty-Year Trends in the Incidence and Outcome of Cardiogenic Shock in AMIS Plus Registry. Circ Cardiovasc Interv 2019; 12:e007293. [DOI: 10.1161/circinterventions.118.007293] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Blaes AH, Petersen A, Beckwith H, Potter D, Florea N, Yee D, Vogel R, Duprez D. Abstract P1-12-06: Endothelial dysfunction in breast cancer survivors on aromatase inhibitors (AIs) over time. Cancer Res 2019. [DOI: 10.1158/1538-7445.sabcs18-p1-12-06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Endothelial dysfunction in breast cancer survivors on aromatase inhibitors (AIs) over time
Background: AIs reduce breast cancer-related mortality however they may increase cardiovascular (CV) risk. Our previously published cross-sectional study suggested women on AIs were more likely to have endothelial dysfunction when measured by EndoPAT ratio as compared to healthy postmenopausal women. Reductions in EndoPAT ratio (<1.67) and small artery elasticity (SAE) and increases in highly sensitive C-reactive protein (CRP) are associated with worsening endothelial dysfunction and increased cardiovascular events. We present data from a longitudinal pilot study looking at endothelial dysfunction over time in women on AIs.
Methods: Fourteen women with locally advanced breast cancer prescribed an AI underwent vascular testing at baseline (pre-AI) and at 6 months. Subjects with tobacco use, hypertension or hyperlipidemia were excluded. Consented subjects underwent biomarker analysis and radial artery pulse wave analysis using the HDI/Pulse Wave CR-2000 CV Profiling System and pulse contour analysis using the Endo-PAT2000 system. Biomarkers were obtained using a fasting blood draw to evaluate the following lipids and inflammatory markers: serum ultrasensitive estradiol, serum glucose, total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglycerides (TG), CRP, plasminogen-activator 1 (PA1), and tissue-type plasminogen activator (tPA). Changes between baseline and follow-up using Wilcoxon signed-rank tests were analyzed.
Results: Mean baseline age was 59 years and median body mass index was 26.5 kg/m2. Median systolic blood pressure and total cholesterol were 120/70 mm/Hg and 228 mg/dL, respectively. Baseline ultrasensitive estradiol levels were 7 pg/mL and hsCRP was 2.45 mg/dL. Prior to AI therapy, endoPAT ratio was 2.18 (1.19, 2.43). After six months, EndoPAT ratio declined to a median 1.12 (0.85, 1.86) (p=0.045). There were no statistically significant changes in serum glucose, TC, LDL, HDL, hsCRP, PA1 and tPA. HsCRP remained elevatedat median 2.98 mg/L. At six months, estradiol levels decreased to a median of 2 pg/mL (p=0.052), however, there appeared to be no linear association between changes in EndoPAT and estradiol (p=0.91).
Conclusion: Breast cancer survivors on AIs have endothelial dysfunction, a predictor of adverse CV disease. These changes develop while on AIs. Underlying pathophysiology requires further evaluation.
Cardiovascular markersMeasuresBaselineFollow-Up at 6 MonthsChangeP-valueBMI (kg/m2)26.5 (24.4, 31.6)27.1 (23.9, 32.9)0.5 (0.0, 1.3)0.056SBP (mmHg)120 (115, 124)123 (114, 127)-0.8 (-7.4, 3.6)0.91DBP (mmHg)70 (61, 73)69 (62, 71)0.0 (-3.0, 2.6)0.88Total Cholesterol (mg/dL)228 (202, 244)213 (210, 229)-1 (-18, 27)0.70HDL (mg/dL)64 (58, 69)73 (61, 77)2 (-3, 14)0.44LDL (mg/dL)143 (121, 159)129 (120, 142)6 (-11, 14)0.65Estradiol (pg/mL)7 (4, 15)2 (2, 3)-8 (-12, -3)0.05hsCRP (mg/dL)2.45 (1.14, 6.07)2.98 (0.90, 4.81)-8 (-12, -3)0.85EndoPAT Ratio2.18 (1.19, 2.43)1.12 (0.85, 1.86)-0.16 (-1.45, -0.02)0.0451.Summaries shown are median (1st quartile, 3rd quartile).
Citation Format: Blaes AH, Petersen A, Beckwith H, Potter D, Florea N, Yee D, Vogel R, Duprez D. Endothelial dysfunction in breast cancer survivors on aromatase inhibitors (AIs) over time [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-12-06.
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Fredi G, Bruenig H, Vogel R, Scheffler C. Melt-spun polypropylene filaments containing paraffin microcapsules for multifunctional hybrid yarns and smart thermoregulating thermoplastic composites. EXPRESS POLYM LETT 2019. [DOI: 10.3144/expresspolymlett.2019.93] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Vogel R. Review of "The Central Nervous System, 5th Edition," by Per Brodal. Neurodiagn J 2018; 58:260-262. [PMID: 30365395 DOI: 10.1080/21646821.2018.1530551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Vogel R, Balzer J, Gertsch J, Holdefer RN, Lee GR, Moreira JJ, Wilent B, Shils JL. Letter: Guidelines for the Use of Electrophysiological Monitoring for Surgery of the Human Spinal Column and Spinal Cord. Neurosurgery 2018; 82:E190-E191. [DOI: 10.1093/neuros/nyy093] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Riley MR, Doan AT, Vogel R, Scheid E. Platform Session – Evoked potentials & NIOM: Use of motor evoked potentials during lateral lumbar interbody fusion reduces postoperative deficits. Clin Neurophysiol 2018. [DOI: 10.1016/j.clinph.2018.04.587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vogel R, Johnson P, Mur T, Roehm P. Platform Session – Evoked potentials & NIOM: Percutaneous threshold of facial nerve stimulation predicts facial canal dehiscence. Clin Neurophysiol 2018. [DOI: 10.1016/j.clinph.2018.04.591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Miller IM, Wittreich J, Vogel R, Cook TJ. The Safety and Efficacy of Topical Norfloxacin Compared with Placebo in the Treatment of Acute, Bacterial Conjunctivitis. Eur J Ophthalmol 2018; 2:58-66. [PMID: 1498569 DOI: 10.1177/112067219200200202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Two hundred and eighty-four patients with acute conjunctivitis were enrolled in a double-masked study comparing norfloxacin ophthalmic solution with placebo. The proportion of patients who were clinically improved after 5 days treatment was 88.1 % in the norfloxacin group and 71.6% in the placebo group (p<0.01). The proportion of patients who had all organisms eradicated, including the coagulase-negative staphylococci, after two to three days treatment was 52.7% for norfloxacin and 23.9% for placebo (p<0.01) and 64.7% and 26.3% (p<0.01) respectively when the coagulase-negative staphylococci were not included. Adverse experiences occurred in 4.2% of the patients receiving norfloxacin compared to 7.1% of the placebo patients. None of the adverse experiences was serious.
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Cherif C, Tran NHA, Kirsten M, Bruenig H, Vogel R. Environmentally friendly and highly productive bi-component melt spinning of thermoregulated smart polymer fibres with high latent heat capacity. EXPRESS POLYM LETT 2018. [DOI: 10.3144/expresspolymlett.2018.19] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Doan A, Vogel R. TO THE EDITOR. Spine (Phila Pa 1976) 2017; 42:E991. [PMID: 28538592 DOI: 10.1097/brs.0000000000002249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Vogel R, Woiwod M, Zijlstra G. OLDER ADULTS’ PREFERENCES REGARDING BEHAVIOUR CHANGE TECHNIQUES IN A FEAR OF FALLING PROGRAM. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.5112] [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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Marisa T, Niederhauser T, Haeberlin A, Wildhaber RA, Vogel R, Goette J, Jacomet M. Pseudo Asynchronous Level Crossing adc for ecg Signal Acquisition. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2017; 11:267-278. [PMID: 28186908 DOI: 10.1109/tbcas.2016.2619858] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A new pseudo asynchronous level crossing analogue-to-digital converter (adc) architecture targeted for low-power, implantable, long-term biomedical sensing applications is presented. In contrast to most of the existing asynchronous level crossing adc designs, the proposed design has no digital-to-analogue converter (dac) and no continuous time comparators. Instead, the proposed architecture uses an analogue memory cell and dynamic comparators. The architecture retains the signal activity dependent sampling operation by generating events only when the input signal is changing. The architecture offers the advantages of smaller chip area, energy saving and fewer analogue system components. Beside lower energy consumption the use of dynamic comparators results in a more robust performance in noise conditions. Moreover, dynamic comparators make interfacing the asynchronous level crossing system to synchronous processing blocks simpler. The proposed adc was implemented in [Formula: see text] complementary metal-oxide-semiconductor (cmos) technology, the hardware occupies a chip area of 0.0372 mm2 and operates from a supply voltage of [Formula: see text] to [Formula: see text]. The adc's power consumption is as low as 0.6 μW with signal bandwidth from [Formula: see text] to [Formula: see text] and achieves an equivalent number of bits (enob) of up to 8 bits.
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Wolfersdorf M, Vogel R, Vogl R, Grebner M, Keller F, Purucker M, Wurst FM. [Suicide in psychiatric hospitals : Results, risk factors and therapeutic measures]. DER NERVENARZT 2017; 87:474-82. [PMID: 27090898 DOI: 10.1007/s00115-016-0111-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Suicide prevention is a core responsibility of psychiatry and psychotherapy. Periods of change in psychiatric inpatient treatment concepts are usually also accompanied by an increase in psychopathological behavior and with increased suicide rates in psychiatric hospitals, as seen in the 1970s and 1980s in Germany. That this represented a real increase of inpatient suicides during those years was confirmed and subsequently the number and rate of inpatient suicides has decreased from approximately 280 out of 100,000 admissions of patients in 1980 to approximately 50 in 2014. Death can also occur in psychiatric hospitals and an absolute prevention is not possible even under optimal conditions of therapy and nursing, communication and security. The suicide rate has clearly decreased over the last two decades in relation to admissions. The group of young male schizophrenic patients newly identified as having a high clinical suicide risk has decreased among the suicide victims whereas the percentage of severely depressed patients with delusions has increased. This reduction could be associated with the comprehensive improvements in educational and training programs in the field of suicide and suicide prevention, objectification of coping methods, development of diagnostic and therapeutic strategies, improvements in therapy and relationship possibilities and a general reduction in the number of suicides in Germany.
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Blaes AH, Beckwith H, Hebbel R, Solovey A, Potter D, Yee D, Vogel R, Luepker R, Duprez D. Abstract S5-07: Aromatase inhibitors and endothelial function: Is there an association with early cardiovascular disease? Cancer Res 2017. [DOI: 10.1158/1538-7445.sabcs16-s5-07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: As more women are cured from their breast cancer, survivors with early stage breast cancer are at greater risk of dying from cardiovascular disease than their breast cancer. Aromatase inhibitors (AI) have been shown to reduce breast cancer-related mortality in women with estrogen receptor (ER)-positive disease which makes up 75% of all breast cancer cases. The use of AIs has been associated with higher rates of hypertension, hypercholesterolemia, angina pectoris and ischemic cardiovascular disease. In the aging population taking AIs, little is known about the direct impact of AIs on endothelial function, a predictor of cardiovascular disease. Endothelial dysfunction identified by reactive hyperemia using Endo-PAT has been associated with an increased risk of cardiac adverse events, independent of Framingham risk score.
Methods: At the University of Minnesota in 2014-2015, 25 healthy postmenopausal women and 36 postmenopausal women with locally advanced breast cancer and prescribed an aromatase inhibitor were identified. Subjects with a history of hypertension or hyperlipidemia were excluded. Consented subjects underwent biomarker analysis and pulse wave analysis using the HDI/Pulse Wave CR-2000 Cardiovascular Profiling System and pulse contour analysis using the Endo-PAT2000 system. Biomarkers and functional test markers were compared between cases and controls using T-tests and Wilcoxon Rank-Sum tests.
Results: Mean age (61.7 vs 58.8 years), body mass index (27.4 vs 26.2 kg/m2), race (93% vs 92% Caucasian), and tobacco use (100% nonsmokers) were similar between cases and controls, respectively. Mean systolic blood pressure (BP) was elevated in cases (128.3 mmHg vs 114.5 mmHg, p=0.0006). There were no differences in lipid profiles. Median ultrasensitive estradiol levels were reduced in cases (2 vs 15 pg/mL, p<0.0001). Median high sensitive C-reactive protein was significantly elevated in cases (4146 vs 1406 ng/L, p=0.05). There were no differences seen in markers of hemostasis or endothelial damage, including circulating endothelial cells, vascular cell adhesion molecule, P-selectin. Median large artery elasticity (12.5 vs 15.1 ml/mmHg, p=0.02), small artery elasticity (5.2 vs 6.7 ml/mmHg, p=0.04), and endoPAT ratio (0.8 vs 2.6, p<0.0001) were significantly reduced in breast cancer survivors on AIs as compared to controls. There was no correlation between use of chemotherapy, radiation therapy, type of AI, or duration of AI use and endothelial function among the cases. When adjusting for differences in BP, endoPAT ratio continued to remain significantly decreased in breast cancer survivors (0.8 vs 2.6, p<0.0001).
Conclusion: Postmenopausal women with breast cancer on AIs have reductions in endothelial function, a predictor of adverse cardiovascular disease (acute coronary syndrome, chest pain, myocardial infarction, cardiac death). With the growing trend that longer duration of endocrine therapy is needed, further work is needed to confirm these findings.
Citation Format: Blaes AH, Beckwith H, Hebbel R, Solovey A, Potter D, Yee D, Vogel R, Luepker R, Duprez D. Aromatase inhibitors and endothelial function: Is there an association with early cardiovascular disease? [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S5-07.
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Vogel R. Schlußbemerkung zur Diskussion mit Herrn E. Jänecke. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-1939-18510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Pulver T, Heilmann W, Richter J, Shahi M, Vogel R, Ghebre R, Bazzaro M. Ubiquitin-Specific Protease 14 is a Biomarker for Recurrence in Early-Stage Endometrial Adenocarcinoma and Potential Therapeutic Target. Gynecol Oncol 2016. [DOI: 10.1016/j.ygyno.2016.08.248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Argyropoulos KV, Vogel R, Ziegler C, Altan-Bonnet G, Velardi E, Calafiore M, Dogan A, Arcila M, Patel M, Knapp K, Mallek C, Hunter ZR, Treon SP, van den Brink MRM, Palomba ML. Clonal B cells in Waldenström's macroglobulinemia exhibit functional features of chronic active B-cell receptor signaling. Leukemia 2016; 30:1116-25. [PMID: 26867669 PMCID: PMC4858584 DOI: 10.1038/leu.2016.8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 11/23/2015] [Accepted: 12/22/2015] [Indexed: 12/19/2022]
Abstract
Waldenström's macroglobulinemia (WM) is a B-cell non-Hodgkin's lymphoma (B-NHL) characterized by immunoglobulin M (IgM) monoclonal gammopathy and the medullary expansion of clonal lymphoplasmacytic cells. Neoplastic transformation has been partially attributed to hyperactive MYD88 signaling, secondary to the MYD88 L265P mutation, occurring in the majority of WM patients. Nevertheless, the presence of chronic active B-cell receptor (BCR) signaling, a feature of multiple IgM+ B-NHL, remains a subject of speculation in WM. Here, we interrogated the BCR signaling capacity of primary WM cells by utilizing multiparametric phosphoflow cytometry and found heightened basal phosphorylation of BCR-related signaling proteins, and augmented phosphoresponses on surface IgM (sIgM) crosslinking, compared with normal B cells. In support of those findings we observed high sIgM expression and loss of phosphatase activity in WM cells, which could both lead to signaling potentiation in clonal cells. Finally, led by the high-signaling heterogeneity among WM samples, we generated patient-specific phosphosignatures, which subclassified patients into a ‘high' and a ‘healthy-like' signaling group, with the second corresponding to patients with a more indolent clinical phenotype. These findings support the presence of chronic active BCR signaling in WM while providing a link between differential BCR signaling utilization and distinct clinical WM subgroups.
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Vogel R. Review of "Handbook for Clinical Research: Design, Statistics, and Implementation," by Flora M. Hammond, James F. Malec, Todd G. Nick, and Ralph M. Buschbacher. Neurodiagn J 2016; 56:220-222. [PMID: 28436769 DOI: 10.1080/21646821.2016.1202719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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Vogel R. Review of "Practical Neurology Visual Review, 2nd Edition," by José Biller and Alberto Espay. Neurodiagn J 2016; 56:218-219. [PMID: 28436764 DOI: 10.1080/21646821.2016.1202717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Chen J, Schneider K, Gao S, Vogel R, Heinrich G. In-situ synchrotron X-ray studies of crystallization of β-nucleated iPP subjected to a wide range of shear rates and shear temperatures. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.08.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Marisa T, Niederhauser T, Haeberlin A, Wildhaber RA, Vogel R, Jacomet M, Goette J. Bufferless Compression of Asynchronously Sampled ECG Signals in Cubic Hermitian Vector Space. IEEE Trans Biomed Eng 2015; 62:2878-87. [PMID: 26126269 DOI: 10.1109/tbme.2015.2449901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Asynchronous level crossing sampling analog-to-digital converters (ADCs) are known to be more energy efficient and produce fewer samples than their equidistantly sampling counterparts. However, as the required threshold voltage is lowered, the number of samples and, in turn, the data rate and the energy consumed by the overall system increases. In this paper, we present a cubic Hermitian vector-based technique for online compression of asynchronously sampled electrocardiogram signals. The proposed method is computationally efficient data compression. The algorithm has complexity O(n), thus well suited for asynchronous ADCs. Our algorithm requires no data buffering, maintaining the energy advantage of asynchronous ADCs. The proposed method of compression has a compression ratio of up to 90% with achievable percentage root-mean-square difference ratios as a low as 0.97. The algorithm preserves the superior feature-to-feature timing accuracy of asynchronously sampled signals. These advantages are achieved in a computationally efficient manner since algorithm boundary parameters for the signals are extracted a priori.
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Lowe M, Spiro A, Vogel R, Donaldson N, Gosselin C. SU-E-E-06: Teaching About the Gamma Camera and Ultrasound Imaging. Med Phys 2015. [DOI: 10.1118/1.4923928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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de Andrade Pereira B, Ackermann M, Chaudhary S, Vogel R, Vogt B, Dresch C, Fraefel C. Tolerance of activated pathogenic CD4+ T cells by transcriptional targeting of dendritic cells. Gene Ther 2015; 22:382-90. [PMID: 25739989 DOI: 10.1038/gt.2015.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/02/2014] [Accepted: 01/15/2015] [Indexed: 01/30/2023]
Abstract
We have recently shown that targeted expression of myelin oligodendrocyte glycoprotein (MOG) to dendritic cells with self-inactivating-lentivirus vectors induces antigen-specific tolerance in naive antigen-specific CD4+ T cells and protects mice from experimental autoimmune encephalomyelitis (EAE). In the present study, we demonstrate that this approach also induces tolerance of activated antigen-specific CD4+ T cells and completely protects mice from passive EAE induction. Tolerance induction did not correlate with the depletion of the preactivated antigen-specific CD4+ T cells. However, upon isolation and in vitro re-stimulation at day 6 after adoptive transfer the MOG-specific CD4+ T cells from the non-tolerized mice produced large amounts of inflammatory cytokines, whereas those from tolerized mice did not. This unresponsiveness correlated with the upregulation of regulatory molecules associated with anergy and regulatory T cells (Tregs). The in vivo depletion of Tregs resulted in EAE susceptibility of the tolerized animals, suggesting that these cells have indeed a role in tolerance induction/maintenance.
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Pospischil A, Hässig M, Vogel R, Salvini MM, Fabrikant S, Axhausen K, Schenker SN, Erni D, Guscetti F. [Dog population and dog breeds in Switzerland from 1955 to 2008]. SCHWEIZ ARCH TIERH 2015; 155:219-28. [PMID: 23531943 DOI: 10.1024/0036-7281/a000450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aim of this study is to present a survey of the dog population and breed distribution in Switzerland from 1955 to 2008 as basis to realize a population based canine cancer register for Switzerland. The number of dogs rose from 309'000 in 1955 to approximately 500'000 in 2008 correlating with a parallel increase of human population. The ratio of dogs per 100 inhabitants remains stable. This ratio is lower in German speaking compared to French or Italian speaking Cantons. The variety and popularity of breeds changed from 1955 to 2008, "winners" are Labrador and Golden Retrievers, Yorkshire and Jack Russel Terriers. Less popular breeds over the years are German Sheherd dogs and Poodles.
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Hinüber C, Chwalek K, Pan-Montojo FJ, Nitschke M, Vogel R, Brünig H, Heinrich G, Werner C. Hierarchically structured nerve guidance channels based on poly-3-hydroxybutyrate enhance oriented axonal outgrowth. Acta Biomater 2014; 10:2086-95. [PMID: 24406197 DOI: 10.1016/j.actbio.2013.12.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/07/2013] [Accepted: 12/26/2013] [Indexed: 01/19/2023]
Abstract
Traumatic peripheral nerve lesions can cause local anesthesia, paralysis and loss of autonomic control. Reconstruction using engineered nerve guidance conduits (NGCs) is rarely successful due to the sub-optimal characteristics of the conduits. To address the demands of clinical practice, we developed a hierarchically structured NGC from slowly resorbing poly(3-hydroxybutyric acid) (P3HB). The NGC consists of a permeable single-lumen tube and melt-spun fibrillar lumen fillers. Permeable tubes were constructed from P3HB/poly(ɛ-caprolactone) (PCL) blends or poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid) (P(3HB-co-4HB)). Polyvinylpyrrolidone was used as a porogen in solvent-free thermoplastic processing, followed by selective polymer leaching. All tested material compositions showed hydrolytic degradation after 16weeks in phosphate buffered saline, whereas P3HB/PCL tubes maintained mechanical strength compared to (P(3HB-co-4HB)). The porous scaffolds allowed diffusion of large molecules (∼70kDa). In vitro studies demonstrated that mouse fibroblasts survived and proliferated inside closed porous tubes. An in vitro model of axonal regeneration using dorsal root ganglia and sympathetic cervical ganglia demonstrated that the NGCs successfully supported neuron survival and neurite outgrowth. The introduction of fibrillar lumen fillers promoted oriented neurite growth and coating with extracellular matrix proteins further increased ganglia attachment and cell migration. In this study we show that P3HB-based NGCs scaffolds have potential in long gap peripheral nerve repair strategies.
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Niederhauser T, Haeberlin A, Marisa T, Mattle D, Abächerli R, Goette J, Jacomet M, Vogel R. An optimized lead system for long-term esophageal electrocardiography. Physiol Meas 2014; 35:517-32. [PMID: 24577330 DOI: 10.1088/0967-3334/35/4/517] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Long-term electrocardiography (ECG) featuring adequate atrial and ventricular signal quality is highly desirable. Routinely used surface leads are limited in atrial signal sensitivity and recording capability impeding complete ECG delineation, i.e. in the presence of supraventricular arrhythmias. Long-term esophageal ECG might overcome these limitations but requires a dedicated lead system and recorder design. To this end, we analysed multiple-lead esophageal ECGs with respect to signal quality by describing the ECG waves as a function of the insertion level, interelectrode distance, electrode shape and amplifier's input range. The results derived from clinical data show that two bipolar esophageal leads, an atrial lead with short (15 mm) interelectrode distance and a ventricular lead with long (80 mm) interelectrode distance provide non-inferior ventricular signal strength and superior atrial signal strength compared to standard surface lead II. High atrial signal slope in particular is observed with the atrial esophageal lead. The proposed esophageal lead system in combination with an increased recorder input range of ±20 mV minimizes signal loss due to excessive electrode motion typically observed in esophageal ECGs. The design proposal might help to standardize long-term esophageal ECG registrations and facilitate novel ECG classification systems based on the independent detection of ventricular and atrial electrical activity.
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Kratz T, Vogel R, Eberling J, Tröster M. [Legal ramifications of medical end-of-life decisions in dementia--orientational certainty through the latest decisions of the German Supreme Court?]. FORTSCHRITTE DER NEUROLOGIE-PSYCHIATRIE 2013; 81:679-88. [PMID: 24307086 DOI: 10.1055/s-0033-1355924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Taking care of dying people is one of the most difficult obligations of the physician, especially if these patients are suffering from dementia and accordingly when their current capacity to consent is arguable. In this field, numerous ethical and forensic problems arise that have to be considered. Legal medical end-of-life decisions that potentially shorten life (Sterbehilfe) are divided into two categories: direct "Sterbehilfe" refers to stopping life-prolonging measures. Indirect "Sterbehilfe" describes the use of agents to alleviate symptoms of a terminally ill patient which may however, shorten life expectancy. A physician terminating a patient's life based on his own decision and authority of action always acts illegally. This paper describes the current discussion on this issue in Germany considering the medical and legal aspects of it while focussing on patients suffering from dementia and their ability to form and to articulate their own will.
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Weller H, Eychmüller A, Vogel R, Katsikas L, Hässelbarth A, Giersig M. Synthesis and Photochemistry of Quantum-Size Semiconductor Particles in Solution and in Modified Layers. Isr J Chem 2013. [DOI: 10.1002/ijch.199300016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Traupe T, Gloekler S, Stoller M, Steck H, Khattab AA, Vogel R, Seiler C. Effect of heart rate reduction by ivabradine on collateral function in patients with chronic stable coronary artery disease. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht309.p3114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Geller M, Petzel S, Vogel R, Chan D, McClellan M, Gerber M, Cragg J, Jacko J, Sainfort F. A novel approach to palliative care and end-of-life decision-making: A patient-centered website to promote health care decision-making. Gynecol Oncol 2013. [DOI: 10.1016/j.ygyno.2013.04.396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hunt CR, Geller M, Evans C, Vogel R, Ramakrishnan S, Saluja A. A water-soluble analog of triptolide induces ovarian cancer cell death in vitro and in vivo. Gynecol Oncol 2013. [DOI: 10.1016/j.ygyno.2013.04.372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Geller M, Petzel S, Vogel R, McClellan M, Jacko J, Cragg J, Gerber M, Chan D, Sainfort F. An interactive website for patients with ovarian cancer and their care givers - can we improve quality of life? Gynecol Oncol 2013. [DOI: 10.1016/j.ygyno.2013.04.411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Dickson E, Vogel R, Downs L. Cervical cytology and HPV infection: A study of 15,565 women. Gynecol Oncol 2013. [DOI: 10.1016/j.ygyno.2013.04.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Vogel R, Brünig H, Beyreuther R, Tändler B, Voigt D. Rheological and Theoretical Estimation of the Spinnability of Polyolefines. INT POLYM PROC 2013. [DOI: 10.3139/217.1518] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Melt spinning is a polymer processing technique that makes great demands on the extensibility of the polymer melt in the distance between die exit and solidification point [1]. The polymer material is exposed to a rapidly growing deformation rate over a large range of deformation within a short time of about 100 milliseconds. Simultaneously an extreme cooling occurs with cooling rates of about 1000 K/s. For this reason only a few polymer materials are usable for this kind of polymer processing with sufficient take-up speeds. Most polymers show a fiber break in the molten state either by brittle cohesive rupture or ductile failure when approaching critical conditions of deformation. The rheological behaviour of a polymer melt at the critical conditions of deformation in the fiber forming process can not be predicted by means of usual rheological material functions. This paper reports the attempt to find out material functions, which describe the critical deformation states of the melt spinning process. The established material functions are compared with the results of spinning experiments to estimate their practicality.
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Beyreuther R, Brünig H, Vogel R. Preferable Filament Diameter Ratios of Hybrid Yarn Components for Optimized Longfiber Reinforced Thermoplastics. INT POLYM PROC 2013. [DOI: 10.3139/217.1681] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
The mechanical properties of hybrid (commingled) yarn based reinforced thermoplastics depend on many parameters of the fiber components as well as of the different technological conditions during the commingling and the hot press molding. Among the fiber parameters the diameter ratio of the matrix and the reinforcing yarn components are most important to obtain best mechanical properties of the reinforced thermoplastics. The paper treats theoretical considerations in order to reach a high probability of coating each reinforcing filament with the thermoplastic material during the hot press molding. The calculations include the filament ratios and the achieved volume ratios of both hybrid yarn components of the finished reinforced thermoplastics. It is demonstrated that under different optimization criterias (same filament numbers for both components or the same surfaces of the reinforcing yarn filaments and the matrix yarn filaments before the hot press molding) a more or less small range of filament ratios seem to be valid for manufacturing a homogeneous faultless reinforced thermoplastic. Quantitative calculations for two hybrid yarn systems PEEK/carbon fibers and PP/glass fibers, presented in diagrams, are demonstrated. Technological conditions for the spinning of micro fibers like PEEK-filaments complete the presentation.
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Beyreuther R, Tändler B, Vogel R, Hoffmann M. Melt Spinning of Reactive Extruded and/or Blended Polymer Fibers by Means of an Online Coupled Twin Screw Extruder. INT POLYM PROC 2013. [DOI: 10.3139/217.1724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
After some general introductory remarks to the advantageous application of a twin screw extrusion to the melt spinning the lecture deals with investigations of elastomeric fibers consisting of ethylene-octene-copolymers which have been grafted by organosilanes and additionally blended with polybutylenter-ephthalates (PBT) and/or polyesterelastomers (PEE), all by means of a reactive twin screw extruder coupled with a side feeding single screw extruder in an online melt spinning process. It will be demonstrated that considerably improved mechanical properties of the elastomeric EO-fibers can be reached with this additional blend step. All spun fiber samples will be characterized regarding their structural and mechanical properties extensively.
This work is a decisive expansion of our results published during the last two years regarding to the twin screw extrusion melt spinning [1 to 4].
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Vogel R, Hatzikiriakos SG, Brünig H, Tändler B, Golzar M. Improved Spinnability of Metallocene Polyethylenes by Using Processing Aids. INT POLYM PROC 2013. [DOI: 10.3139/217.1722] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Melt spinning is a polymer processing technique that is strongly influenced by the extensional flow behaviour of polymer melts. Therefore only a few polymeric materials are usable for this kind of processing with sufficient take-up speeds. When approaching critical conditions of deformation most polymers show either fibre break in the molten state either by a brittle cohesive rupture or a ductile failure. During the melt spinning of pure and modified metallocene poylethylenes additional flow instabilities occur within the spinning die. Namely, wall slip, ‘sharkskin’ and pressure oscillations (gross fracture) may be obtained dependending on the volume flow rate. Pressure oscillations lead to diameter oscillations of the melt extrudate, which create local increase of tensile stress in the spin line. This effect immediately causes fiber break in the spinline.
Therefore, melt spinning of polyethylenes was only possible up to a critical molecular weight or its relating melt viscosity. The limitation of the molecular weight restricts the mechanical properties of the melt spun fibres. This paper reports on an attempt to find out appropriate processing aids for suppressing ‘sharkskin’ effects and pressure oscillations in an attempt to overcome the limitation of a critical molecular weight. At first, the critical conditions for the onset of flow instabilities for higher molecular weight polymers were analysed. Further experiments concerned with the use of processing aids for melt spinning of metallocene polyethylenes of higher molecular weights. A combination of boron nitride powder and a fluoroelastomer was found to be an effective processing aid for this process.
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