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Rau S, Nied C, Schmidt S, Niedziela D, Lindner J, Sommer K. Multi-phase simulation of pneumatic conveying applying a hydrodynamic hybrid model for the granular phase. POWDER TECHNOL 2018. [DOI: 10.1016/j.powtec.2018.02.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Nagesh SVS, Hinaman J, Sommer K, Xiong Z, Ionita CN, Bednarek DR, Rudin S. A simulation platform using 3D printed neurovascular phantoms for clinical utility evaluation of new imaging technologies. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2018; 10578. [PMID: 29887667 DOI: 10.1117/12.2293630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Modern 3D printing technology allows rapid prototyping of vascular phantoms based on an actual human patient with a high degree of precision. Using this technology, we present a platform to accurately simulate clinical views of neuro-endovascular interventions and devices. The neuro-endovascular interventional phantom has a 3D printed cerebrovasculature model derived from a patient CT angiogram and embedded inside a human skull providing bone attenuation. Acrylic layers were placed underneath and on top of the skull, simulating entrance and exit tissue attenuation and also simulating forward scatter. The 3D model was connected to a pulsatile flow loop for simulating interventions using clinical devices such as catheters and stents. To validate the x-ray attenuation and establish clinical accuracy, the automatic exposure selection by a clinical c-arm system for the phantom was compared with that for a commercial anthropomorphic head phantom (SK-150, Phantom Labs). The percentage difference between automatic exposure selection for the neuro-intervention phantom and the SK-150 phantom was under 10%. By changing 3D printed models, various patient diseased anatomies can be simulated accurately with the necessary x-ray attenuation. Using this platform various interventional procedures were performed using new imaging technologies such as a high-resolution x-ray fluoroscope and a dose-reduced region-of-interest attenuator and differential temporally filtered display for enhanced interventional imaging. Simulated clinical views from such phantom-based procedures were used to evaluate the potential clinical performance of such new technologies.
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Sommer K, Gerl J, Hof V, Surowiec A, Richter E, Wollenberg B, Baehre M, Meller B. High energy probe for detecting lymph node metastases with 18F-FDG in patients with head and neck cancer. Nuklearmedizin 2018. [DOI: 10.1055/s-0038-1625113] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
SummaryAim of this study was to validate a newly developed high energy probe (positron emission probe, PEP) optimised for localising PET tracers in vivo. Patients and methods: Physical investigations included determination of full width at half maximum (FWHM) values at a distance of 1 cm and angular resolution using different point sources. Values obtained with the new probe were compared to those of a conventional gamma probe (CGP). Additionally, PET studies were performed in 36 patients (6 women, 30 men) with proven head and neck cancer and suspected lymph node metastases (Axis, Marconi/Philips) after administering 250–320 MBq 18F-FDG. Subsequent to PET investigations 18F-FDG uptake in cervical regions was measured using the PEP. PEP investigations were carried out bilaterally in 5 lymph node (LN) levels (Robbins’ classification of the neck). Results of probe studies were correlated with visual and semiquantitative PET evaluations, US and histological findings. Results: FWHM of the new probe was 7 mm (CGP 22 mm) at 662 keV (137Cs) and angular resolution resulted in 8° (CGP 60°). In 29 out of 36 patients LN metastases were suspected due to ultrasound investigations. After neck dissection, histology confirmed LN metastases in 21 patients. Sensitivity (sens.) of US amounted to 95% and specificity to 40%. In 18/21 patients LN metastases were detected by PET (sens. 86%). PET scans failed to diagnose the LN status correctly in 6/36 patients (accuracy 83%). Employing the PEP probe in 20/21 patients LN metastases were identified (sens. 95%), and LN status was determined accurately in 29/36 patients (accuracy 81%). Tumour/ background ratios of PEP measurement and results of semiquantitative PET analyses were comparable. Conclusions: PEP measurement is a promising method for preoperative planning of the extent of neck dissection in patients with head and neck cancer and further for radioguided localising PET tracer accumulation during surgery.
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Nied C, Lindner J, Sommer K. On the influence of the wall friction coefficient on void fraction gradients in horizontal pneumatic plug conveying measured by electrical capacitance tomography. POWDER TECHNOL 2017. [DOI: 10.1016/j.powtec.2017.07.072] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Sommer K, Amthor T, Doneva M, Koken P, Meineke J, Börnert P. Towards predicting the encoding capability of MR fingerprinting sequences. Magn Reson Imaging 2017; 41:7-14. [PMID: 28684268 DOI: 10.1016/j.mri.2017.06.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 11/19/2022]
Abstract
Sequence optimization and appropriate sequence selection is still an unmet need in magnetic resonance fingerprinting (MRF). The main challenge in MRF sequence design is the lack of an appropriate measure of the sequence's encoding capability. To find such a measure, three different candidates for judging the encoding capability have been investigated: local and global dot-product-based measures judging dictionary entry similarity as well as a Monte Carlo method that evaluates the noise propagation properties of an MRF sequence. Consistency of these measures for different sequence lengths as well as the capability to predict actual sequence performance in both phantom and in vivo measurements was analyzed. While the dot-product-based measures yielded inconsistent results for different sequence lengths, the Monte Carlo method was in a good agreement with phantom experiments. In particular, the Monte Carlo method could accurately predict the performance of different flip angle patterns in actual measurements. The proposed Monte Carlo method provides an appropriate measure of MRF sequence encoding capability and may be used for sequence optimization.
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Sander AL, Sommer K, Schäf D, Braun C, Marzi I, Pohlemann T, Frank J. Clinical outcome after alternative treatment of scaphoid fractures and nonunions. Eur J Trauma Emerg Surg 2017; 44:113-118. [PMID: 28243717 DOI: 10.1007/s00068-017-0773-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/08/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE Achieving stable fixation of scaphoid fractures and nonunions continues to be a challenge. Compression screw fixation has been the current standard surgical procedure. However, in some cases, bone healing cannot be achieved and requires further revision. Recent series reintroduced volar plating as valid option for stable fixation. The aim of the study was to review clinical outcome of alternative scaphoid treatment. METHODS From 2011 to 2014, nine patients with scaphoid fracture were treated by Headless Compression Screw (HCS) and seven patients with scaphoid nonunion by HCS or volar mini condylar plate with bone graft. The average age was 34.4 years and the average time to follow-up was 19.3 months. From 1996 to 1998, 38 patients with scaphoid nonunion were treated using compression screw (S-group) or volar mini condylar plate (P-group) with bone graft. The average age was 39.6 years and the average time to follow-up was 26.2 months. RESULTS The union rate was 100%. For scaphoid fractures, the mean Modified Mayo Wrist Score (MMWS) was 94.1 and the DASH score 7.4. From 2011 to 2014, the MMWS was 87.9 and the DASH score 7 in scaphoid nonunions. In the period between 1996 and 1998, the MMWS was 67.2 in the P-group and 58.6 in the S-group, and the DASH score 16.8 and 28.2. CONCLUSIONS Our study demonstrated that appropriate application of the HCS was able to produce very satisfactory results in scaphoid fractures and nonunions. In our opinion, however, the method of scaphoid plate osteosynthesis can achieve a higher degree of stability, particularly rotational stability, in case of multifragmentary avascular scaphoid nonunions.
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Affolter A, Samosny G, Heimes AS, Schneider J, Weichert W, Stenzinger A, Sommer K, Jensen A, Mayer A, Brenner W, Mann WJ, Brieger J. Multikinase inhibitors sorafenib and sunitinib as radiosensitizers in head and neck cancer cell lines. Head Neck 2017; 39:623-632. [DOI: 10.1002/hed.24557] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 05/27/2016] [Accepted: 06/24/2016] [Indexed: 12/16/2022] Open
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Gargya A, Chua E, Hetherington J, Sommer K, Cooper M. Acute adrenal insufficiency: an aide-memoire of the critical importance of its recognition and prevention. Intern Med J 2016; 46:356-9. [PMID: 26968598 DOI: 10.1111/imj.12998] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 11/14/2015] [Accepted: 12/16/2015] [Indexed: 11/27/2022]
Abstract
Adrenal crisis is a life-threatening emergency that causes significant excess mortality in patients with adrenal insufficiency. Delayed recognition by medical staff of an impending adrenal crisis and failure to give timely hydrocortisone therapy within the emergency department continue to be commonly encountered, even in metropolitan teaching hospitals. Within the authors' institutions, several cases of poorly handled adrenal crises have occurred over the last 2 years. Anecdotal accounts from members of the Addison's support group suggest that these issues are common in Australia. This manuscript is a timely reminder for clinical staff on the critical importance of the recognition, treatment and prevention of adrenal crisis. The manuscript: (i) outlines a case and the clinical outcome of sub-optimally managed adrenal crisis, (ii) summarises the clinical features and acute management of adrenal crisis, (iii) provides recommendations on the prevention of adrenal crisis and (iv) provides guidance on the management of 'sick days' in patients with adrenal insufficiency.
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Semmelmann K, Nordt M, Sommer K, Röhnke R, Mount L, Prüfer H, Terwiel S, Meissner TW, Koldewyn K, Weigelt S. U Can Touch This: How Tablets Can Be Used to Study Cognitive Development. Front Psychol 2016; 7:1021. [PMID: 27458414 PMCID: PMC4935681 DOI: 10.3389/fpsyg.2016.01021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 06/21/2016] [Indexed: 11/13/2022] Open
Abstract
New technological devices, particularly those with touch screens, have become virtually omnipresent over the last decade. Practically from birth, children are now surrounded by smart phones and tablets. Despite being our constant companions, little is known about whether these tools can be used not only for entertainment, but also to collect reliable scientific data. Tablets may prove particularly useful for collecting behavioral data from those children (1-10 years), who are, for the most part, too old for studies based on looking times and too young for classical psychophysical testing. Here, we analyzed data from six studies that utilized touch screen tablets to deliver experimental paradigms in developmental psychology. In studies 1 and 2, we employed a simple sorting and recall task with children from the ages of 2-8. Study 3 (ages 9 and 10) extended these tasks by increasing the difficulty of the stimuli and adding a staircase-based perception task. A visual search paradigm was used in study 4 (ages 2-5), while 1- to 3-year-olds were presented with an extinction learning task in study 5. In study 6, we used a simple visuo-spatial paradigm to obtain more details about the distribution of reaction times on touch screens over all ages. We collected data from adult participants in each study as well, for comparison purposes. We analyzed these data sets in regard to four metrics: self-reported tablet usage, completeness of data, accuracy of responses and response times. In sum, we found that children from the age of two onwards are very capable of interacting with tablets, are able to understand the respective tasks and are able to use tablets to register their answers accordingly. Results from all studies reiterated the advantages of data collection through tablets: ease of use, high portability, low-cost, and high levels of engagement for children. We illustrate the great potential of conducting psychological studies in young children using tablets, and also discuss both methodological challenges and their potential solutions.
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Affolter A, Muller MF, Sommer K, Stenzinger A, Zaoui K, Lorenz K, Wolf T, Sharma S, Wolf J, Perner S, Weber KJ, Freier K, Plinkert PK, Hess J, Weichert W. Targeting irradiation-induced mitogen-activated protein kinase activation in vitro and in an ex vivo model for human head and neck cancer. Head Neck 2016; 38 Suppl 1:E2049-61. [PMID: 26918677 DOI: 10.1002/hed.24376] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/28/2015] [Accepted: 12/04/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Despite new radiotherapeutic strategies, radioresistance in head and neck squamous cell carcinoma (HNSCC) remains a major problem. Preclinical model systems are needed to identify resistance mechanisms in this heterogeneous entity. METHODS We elucidated the interplay among mitogen-activated protein kinase (MAPK)-inhibition, radiation, and p53 mutations in vitro and in a novel ex vivo model derived from vital human HNSCC samples. HNSCC cell lines (p53WT/mut) were treated with the mitogen-activated protein kinase (MEK)-inhibitor PD-0325901 and subsequently irradiated. Radiosensitization was functionally assessed and evaluated in the ex vivo model. RESULTS We observed a pronounced irradiation-induced extracellular signal-regulated kinase (ERK) phosphorylation in 2 cell lines, which was independent of their p53 mutation status and associated with PD-0325901-related radiosensitization in a clonogenic assay. Heterogeneity in irradiation-induced ERK phosphorylation and in radiosensitization after MEK-inhibition was also reflected in the ex vivo model. CONCLUSION We provide experimental evidence for radiosensitizing effects of PD-0325901 in HNSCC. The ex vivo culture technology might offer a promising tool for individualized drug efficacy testing. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2049-E2061, 2016.
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Scheuren H, Sommer K, Dillenburger M. Explanation for the increase in free dimethyl sulphide during mashing. JOURNAL OF THE INSTITUTE OF BREWING 2015. [DOI: 10.1002/jib.234] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Scheuren H, Feilner R, Sommer K, Dillenburger M. Validation and discussion of the vaporization surface. JOURNAL OF THE INSTITUTE OF BREWING 2015. [DOI: 10.1002/jib.231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Wirth W, Sommer K, von Pape T, Karnowski V. Success in online searches: Differences between evaluation and finding tasks. J Assoc Inf Sci Technol 2015. [DOI: 10.1002/asi.23389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sridhar B, Sommer K. Mathematical modeling of grinding kinetics of food particulates. FOOD AND BIOPRODUCTS PROCESSING 2015. [DOI: 10.1016/j.fbp.2014.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Scheuren H, Tippmann J, Methner FJ, Sommer K. Decomposition kinetics of dimethyl sulphide. JOURNAL OF THE INSTITUTE OF BREWING 2014. [DOI: 10.1002/jib.156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Lecreps I, Orozovic O, Jones M, Sommer K. Application of the principles of gas permeability and stochastic particle agitation to predict the pressure loss in slug flow pneumatic conveying systems. POWDER TECHNOL 2014. [DOI: 10.1016/j.powtec.2014.01.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lecreps I, Orozovic O, Eisenmenger M, Jones M, Sommer K. Methods for in-situ porosity determination of moving porous columns and application to horizontal slug flow pneumatic conveying. POWDER TECHNOL 2014. [DOI: 10.1016/j.powtec.2013.12.023] [Citation(s) in RCA: 17] [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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Sommer K, Sander AL, Albig M, Weber R, Henrich D, Frank J, Marzi I, Jakob H. Delayed wound repair in sepsis is associated with reduced local pro-inflammatory cytokine expression. PLoS One 2013; 8:e73992. [PMID: 24086305 PMCID: PMC3783436 DOI: 10.1371/journal.pone.0073992] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/26/2013] [Indexed: 11/18/2022] Open
Abstract
Sepsis is one of the main causes for morbidity and mortality in hospitalized patients. Moreover, sepsis associated complications involving impaired wound healing are common. Septic patients often require surgical interventions that in-turn may lead to further complications caused by impaired wound healing. We established a mouse model to the study delayed wound healing during sepsis distant to the septic focus point. For this reason cecal ligation and puncture (CLP) was combined with the creation of a superficial wound on the mouse ear. Control animals received the same procedure without CPL. Epithelialization was measured every second day by direct microscopic visualization up to complete closure of the wound. As interplay of TNF-α, TGF-β, matrix metalloproteinases (MMP), and tissue inhibitors of metalloproteinases (TIMP) is important in wound healing in general, TNF-α, TGF-β, MMP7, and TIMP1 were assessed immunohistochemical in samples of wounded ears harvested on days 2, 6, 10 and 16 after wounding. After induction of sepsis, animals showed a significant delay in wound epithelialization from day 2 to 12 compared to control animals. Complete wound healing was attained after mean 12.2± standard deviation (SD) 3.0 days in septic animals compared to 8.7± SD 1.7 days in the control group. Septic animals showed a significant reduction in local pro-inflammatory cytokine level of TNF-α on day 2 and day 6 as well as a reduced expression of TGF-β on day 2 in wounds. A significant lower expression of MMP7 as well as TIMP1 was also observed on day 2 after wounding. The induction of sepsis impairs wound healing distant to the septic focus point. We could demonstrate that expression of important cytokines for wound repair is deregulated after induction of sepsis. Thus restoring normal cytokine response locally in wounds could be a good strategy to enhance wound repair in sepsis.
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Sridhar B, Sommer K. Fracture Behavior of Turmeric (Curcuma Longa
) under Ambient and Cryogenic Conditions. J FOOD PROCESS ENG 2013. [DOI: 10.1111/jfpe.12028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Sander AL, Sommer K, Neumayer T, Fleming I, Marzi I, Barker JH, Frank J, Jakob H. Soluble epoxide hydrolase disruption as therapeutic target for wound healing. J Surg Res 2013; 182:362-7. [DOI: 10.1016/j.jss.2012.10.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 09/23/2012] [Accepted: 10/17/2012] [Indexed: 12/22/2022]
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Sridhar BS, Sommer K. Finite Element Simulation of Fracture Mechanism of Fibrous Food. INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2013. [DOI: 10.1080/10942912.2010.535190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Feyerabend T, Steeves R, Jager B, Wiedemann G, Sommer K, Richter E, Katschinski D, Robins H. Local hyperthermia, hyperfractionated radiation, and cisplatin in preirradiated recurrent lymph node metastases of recurrent head and neck cancer. Int J Oncol 2012; 10:591-5. [PMID: 21533418 DOI: 10.3892/ijo.10.3.591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Large tumor size is a negative prognostic variable for attaining complete regression (CR) with local hyperthermia (HT) and radiotherapy (RT). Such poor prognosis lesions (i.e., >7 cm(2) or >14 cm(3)) have an expected CR rate of similar to 30+/-8%. To improve on this result we added cisplatin to HT and RT with standard fractionation (std Fx) in an earlier study, and observed a 19% CR rate in head and neck (H&N) patients. We now report the results of a second generation trial combining HT, cisplatin (40 mg/m(2)) and hyperfractionated RT in a series of 13 pretreated poor prognosis H&N patients. Therapy encompassed 44 triple modality sessions and was well tolerated: toxicity included one episode of grade-3 skin reaction and one grade 1 leukopenia. Although the overall remission rate was 92%, the CR rate was only 8%; this resulted in early closure of this trial concluding that hyperfractionated RT had no (over std Fx RT) benefit in this combined modality approach.
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Sommer K, Van der Molen M, De Pascalis V. Individual differences in the emotional modulation of prepulse inhibition: An ERP study. Int J Psychophysiol 2012. [DOI: 10.1016/j.ijpsycho.2012.07.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Haeffner B, Voigt J, Sommer K. Neue Verfahrensschritte und Ansätze zur Optimierung der anaeroben Fermentation aus Lebensmittelreststoffen. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Seeger FH, Rasper T, Fischer A, Muhly-Reinholz M, Hergenreider E, Leistner DM, Sommer K, Manavski Y, Henschler R, Chavakis E, Assmus B, Zeiher AM, Dimmeler S. Heparin disrupts the CXCR4/SDF-1 axis and impairs the functional capacity of bone marrow-derived mononuclear cells used for cardiovascular repair. Circ Res 2012; 111:854-62. [PMID: 22821930 DOI: 10.1161/circresaha.112.265678] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
RATIONALE Cell therapy is a promising option for the treatment of acute or chronic myocardial ischemia. The intracoronary infusion of cells imposes the potential risk of cell clotting, which may be prevented by the addition of anticoagulants. However, a comprehensive analysis of the effects of anticoagulants on the function of the cells is missing. OBJECTIVE Here, we investigated the effects of heparin and the thrombin inhibitor bivalirudin on bone marrow-derived mononuclear cell (BMC) functional activity and homing capacity. METHODS AND RESULTS Heparin, but not bivalirudin profoundly and dose-dependently inhibited basal and stromal cell-derived factor 1 (SDF-1)-induced BMC migration. Incubation of BMCs with 20 U/mL heparin for 30 minutes abrogated SDF-1-induced BMC invasion (16±8% of control; P<0.01), whereas no effects on apoptosis or colony formation were observed (80±33% and 100±44% of control, respectively). Pretreatment of BMCs with heparin significantly reduced the homing of the injected cells in a mouse ear-wound model (69±10% of control; P<0.05). In contrast, bivalirudin did not inhibit in vivo homing of BMCs. Mechanistically, heparin binds to both, the chemoattractant SDF-1 and its receptor, chemokine receptor 4 (CXCR4), blocking CXCR4 internalization as well as SDF-1/CXCR4 signaling after SDF-1 stimulation. CONCLUSIONS Heparin blocks SDF-1/CXCR4 signaling by binding to the ligand as well as the receptor, thereby interfering with migration and homing of BMCs. In contrast, the thrombin inhibitor bivalirudin did not interfere with BMC homing or SDF-1/CXCR4 signaling. These findings suggest that bivalirudin but not heparin might be recommended as an anticoagulant for intracoronary infusion of BMCs for cell therapy after cardiac ischemia.
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