TY - JOUR A1 - Hornberger, Helga A1 - Witte, Frank A1 - Hort, Norbert A1 - Müller, Wolf-Dieter T1 - Effect of fetal calf serum on the corrosion behaviour of magnesium alloys JF - Materials Science and Engineering B N2 - The corrosion behaviour of WE43 magnesium alloys using the mini cell system was studied. Voltammetry and impedance spectroscopy were applied to study on the one hand the effect of microstructure of the working electrode and on the other hand the effect of proteins in the electrolyte. Two types of alloy samples were produced (i) by permanent mould casting and (ii) by gas atomization followed by extrusion. The results showed that the microstructure was strongly influenced by the production process. The extruded samples showed an improved homogeneity of phase distribution compared with cast samples as it was aimed for. Due to increased homogeneity it was expected to find higher corrosion resistance. However, the electrochemical results are contradictory and suggest an additional phase in the extruded microstructure. Using energy dispersive X-ray spectroscopy (EDX) the secondary magnesium rare earths (RE) phase of extruded samples showed differing composition than of cast samples as well as additional oxide phases. After the samples were electrochemically investigated in cell medium with and without fetal calf serum (FCS), an impact of FCS was detected in voltammetry due to the length of the polarisation curve. As the tip of the mini cell in contact with the working electrode is small, developing gases tend to spread on the working electrode and break the contact of liquid to the counter electrode; which results in disrupting the current flow. This effect was more pronounced when rising the voltage and was found reduced when using electrolytes with FCS. Impedance spectra were slightly deformed by FCS, seen as a kinetic effect but not as a basic differing corrosion reaction. The insight into the effects of FCS was provided by the mini cell system as this system enables to collect entire series of measurements. In contrast of two single measurements, those series reflected the slight difference caused by FCS. The focus of the electrochemical corrosion study was set on the first half hour of immersion. KW - Magnesium KW - Corrosion KW - Proteins KW - Impedance KW - Reproducibility KW - Polarization Y1 - 2011 U6 - https://doi.org/10.1016/j.mseb.2011.07.018 VL - 176 IS - 29 SP - 1746 EP - 1755 ER - TY - JOUR A1 - Manaranche, Claire A1 - Hornberger, Helga T1 - A proposal for the classification of dental alloys according to their resistance to corrosion JF - Dental Materials N2 - Objectives The purpose of this study was to establish a method to compare and classify dental alloys in relation to their resistance to corrosion. Methods Alloy samples and pure metal samples were prepared and tested in chemical and electrochemical corrosion according to ISO 10271. For electrochemical test, the rest potential versus time and a potentiodynamic scan were recorded. After chemical corrosion test, the ions released were analyzed by ICP (induced coupled plasma) spectroscopy. Results High gold alloys had a similar polarization curve than gold. The same effect was observed for Pd–base alloys, their curves were similar to the one of palladium. The ions released during chemical corrosion were non-precious metallic ions. Thereby Ni–Cr alloys were found to release the most ions. Au–Pt alloys showed the highest release of ions compared with other precious alloys but low compared with Ni–Cr. Electrochemical corrosion was more aggressive than chemical corrosion and every type of elements was etched, the higher the precious metal content, the higher the resistance to corrosion of the alloy. Discussion Using the recorded data, a classification system for electrochemical corrosion was developed and discussed to judge the results. Hereby were gold and zinc used as reference materials. The applied classification system defines five classes and it is proposed that alloys of class V are not acceptable. For chemical corrosion resistance, three classes were distinguished according to the quantity of metallic ions released and it is proposed that class III (100–1000 μg/cm2 week) is not acceptable. Palladium and Pd–base alloys showed a higher electrochemical and chemical corrosion resistance than gold. KW - Dental alloys KW - Precious alloys KW - Corrosion test KW - Resistance to corrosion KW - Classification KW - Ion release Y1 - 2007 U6 - https://doi.org/10.1016/j.dental.2006.11.030 VL - 23 IS - 11 SP - 1428 EP - 1437 ER - TY - JOUR A1 - Müller, Wolf-Dieter A1 - Hornberger, Helga T1 - The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys JF - International Journal of Molecular Science N2 - Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE) is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys. KW - magnesium KW - magnesium alloys KW - magnesium hydride KW - corrosion Y1 - 2014 U6 - https://doi.org/10.3390/ijms150711456 VL - 15 SP - 11456 EP - 11472 ER - TY - JOUR A1 - Hornberger, Helga A1 - Virtanen, Sannakaisa A1 - Boccaccini, Aldo R. T1 - Biomedical coatings on magnesium alloys BT - a review JF - Acta Biomaterialia N2 - This review comprehensively covers research carried out in the field of degradable coatings on Mg and Mg alloys for biomedical applications. Several coating methods are discussed, which can be divided, based on the specific processing techniques used, into conversion and deposition coatings. The literature review revealed that in most cases coatings increase the corrosion resistance of Mg and Mg alloys. The critical factors determining coating performance, such as corrosion rate, surface chemistry, adhesion and coating morphology, are identified and discussed. The analysis of the literature showed that many studies have focused on calcium phosphate coatings produced either using conversion or deposition methods which were developed for orthopaedic applications. However, the control of phases and the formation of cracks still appear unsatisfactory. More research and development is needed in the case of biodegradable organic based coatings to generate reproducible and relevant data. In addition to biocompatibility, the mechanical properties of the coatings are also relevant, and the development of appropriate methods to study the corrosion process in detail and in the long term remains an important area of research. KW - Magnesium alloyn KW - Biodegradable materials KW - Coatings KW - Conversion KW - Deposition Y1 - 2012 U6 - https://doi.org/10.1016/j.actbio.2012.04.012 VL - 8 IS - 7 SP - 2442 EP - 2455 ER - TY - RPRT A1 - Deglmann, Markus A1 - Ritthaler, Markus A1 - Raptis, Georgios T1 - Leitfaden für die Umsetzung des Reha-Konsils mittels HL7 FHIR BT - Projekt: Digitales Rehabilitationskonsil mit Anbindung an die Telematik-Infrastruktur N2 - Im Rahmen eines Forschungsprojektes soll eine Plattform für die Vermittlung von Telekonsilen und die Bereitstellung einer Konsilakte an die Telematik-Infrastruktur (TI) angeschlossen werden. Um sowohl eine bestmögliche Skalierbarkeit als auch eine optimale Integrierbarkeit in bestehende Systeme und Anwendungen zu erreichen, wurde HL7 FHIR als syntaktischer Standard für das Reha-Konsil festgelegt. Dieses Dokument liefert einen systematischen Überblick über die notwendigen Schritte und Voraussetzungen, um diesen Anschluss zu bewerkstelligen. Y1 - 2022 U6 - https://doi.org/10.13140/RG.2.2.25217.33120 ER - TY - JOUR A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Horn, Lars-Christian T1 - Bedeutung der Familienanamnese bei Zervixkarzinom JF - Zentralblatt für Gynäkologie N2 - Fragestellung: Molekulare Analysen haben deutlich gemacht, dass maligne Tumoren durch Veränderungen des Genoms hervorgerufen werden. Im Gegensatz zu den erblich bedingten Tumorerkrankungen sind die Kenntnisse zur Bedeutung familiärer Faktoren bei den sog. sporadischen Tumoren, insbesondere beim Zervixkarzinom (CX) begrenzt. Material und Methode: Patientinnen des CX-Registers der Universitäts-Frauenklinik wurden retrospektiv bezüglich der Familienanamnese (FA) analysiert. Als positive FA wurde eine maligne Tumorerkrankung bei einem oder mehreren Verwandten ersten Grades definiert. Es wurde unterschieden, ob es sich um Zervixkarzinome, andere gynäkologische Malignome (außer Mammakarzinom) oder eine extragenitale Lokalisation handelte. Diese Daten wurden zum Erkrankungsalter und zum Nachweis pelviner Lymphknotenmetastasen in Beziehung gesetzt. Ergebnisse: 159/737 Frauen (21,6 %) wiesen eine positive FA auf. In 10,7 % der Fälle war mehr als ein Verwandter ersten Grades erkrankt; bei 6,9 % Angehörige ersten und zweiten Grades. Weibliche Verwandte ersten Grades von 42 Frauen wiesen Malignome des weiblichen Genitaltraktes (außer CX) auf. In 6,9 % waren die Mutter und/oder die Schwester an einem Zervixkarzinom erkrankt. Das Durchschnittsalter der Patientinnen mit positiver Familienanamnese (FA) unterschied sich nicht von dem derjenigen mit leerer FA, wohl aber bei getrennter Betrachtung nach der Tumorlokalisation. Bezüglich des Tumorstadiums (pTNM) und der Zahl der Patientinnen mit histologisch nachgewiesenen pelvinen Lymphknotenmetastasen bestand kein Unterschied. Schlussfolgerungen: Die bisherigen Ergebnisse deuten auch beim Zervixkarzinom auf eine familiäre Belastung hin. Dabei existieren offenbar Familien, in denen mit HPV-assoziierte Präkanzerosen bzw. Tumoren vermehrt auftreten. Besonders gefährdet sind Patientinnen, deren weibliche Anverwandte ersten Grades bereits an einer zervikalen Präkanzerose (besonders CIN III) oder einem invasiven CX erkrankt sind. Diese Frauen sollten einem engmaschigen Screening unterzogen werden. T2 - Impact of familiar history in cervical cancer patients KW - Gebärmutterhalskrebs KW - Familienanamnese KW - Zervixkarzinom KW - hereditär KW - familiär KW - Anamnese KW - Karzinom KW - Prognose Y1 - 2001 U6 - https://doi.org/10.1055/s-2001-14791 VL - 123 SP - 302 EP - 307 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Nenning, Hans T1 - DNA cytometric analysis of surgically treated squamous cell cancer of the uterine cervix, stage pT1b1-pT2b JF - Analytical and quantitative cytology and histology N2 - Objective: To determine the utility of DNA content and DNA-related variables of proliferative activity regarding prognosis in cervical cancer. Study design: DNA image (ICM) andflow cytometry (FCM) were performed to determine the DNA index (DI), 5c-exceeding rate (5c-ER), S-phase fraction (SPF) and proliferation index (PI) in 163 patients with surgically staged pT1b1-pT2b squamous cell cancer of the uterine cervix and treated with primary radical hysterectomy. ICM was performed on imprint cytology, obtained from fresh tumor tissue, which was also used for FCM. Results were analyzed using the chi2 test and Cox regression analysis for risk of pelvic lymph node involvement, tumor recurrence and recurrence-free survival (RFS). Results: ICM was performed on all 163 and FCM on 133 samples. One-third of the tumors showed DNA aneuploidy. Analysis demonstrated prognostic significance of a DI > or = 1.70, with a (70:30) 2.3-fold risk of recurrence (P=.024) and reduced RFS of 10 months (P=.003) in cases of DI > or = 1.70. A high 5c-ER > 11% was associated with pelvic lymph node involvement and decreased RFS (P < or = .04). Significantly more relapses were found in tumors with SPF > 12% (70.8% vs. 29.2%, P=.007). RFS was markedly reduced in tumors with high SPF (52.3 vs. 61.1 months, P=.011). Low proliferative tumors (PI<25%) were associated with lower stage (P=.036) and increased RFS (61.2 vs. 47.1 months, P=.028). In multivariate analysis of clinicopathologic variables (pT category, nodal status, lymphovascular space involvement) and DNA related variables, pelvic lymph node involvement was the only significant predictor of RFS. In patients with nodal involvement, tumors with DI >1.70 were associated with lessfavorable outcomes. Conclusion: DNA-related variables of cell cycle analysis were valuablefor predicting prognosis in cervical cancer patients. Tumors with DI>1.70, 5c-ER >11% and high proliferative activity (SPF>12%, PI>25%) represent a subgroup with a poor prognosis. KW - Gebärmutterhals KW - squamöser Krebs KW - Cytometrie KW - Chirurgie Y1 - 2002 VL - 24 IS - 1 SP - 23 EP - 29 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Pippig, S. A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Köhler, U. A1 - Hentschel, Bettina A1 - Martin, Rosemarie T1 - Clinical relevance of urokinase-type plasminogen activator and its inhibitor type-1 (PAI-1) in squamous cell carcinoma of the uterine cervix JF - Australian and New Zealand Journal of Obstetrics and Gynaecology N2 - Objective The expression of uPA and PAI‐1 as parameters of tumour‐associated proteolysis has been implicated in the process of tumour cell invasion and the metastatic process. However, there is limited information on the impact of these parameters in cervical carcinoma. Methods Quantitative levels for uPA (n = 114) and PAI‐1 (n = 103) were researched in operatively treated, surgically staged squamous cell cancer of the uterine cervix, using an ELISA‐technique. Results were assessed regarding their impact in predicting pelvic lymph nodes metastases, tumour recurrence rate and recurrence free survival (RFS) using uni‐ and multivariate analysis. Results Median levels of both parameters were significantly higher in tumour tissue than in normal cervical tissue (p < 0.001). Detection of uPA gave no useful prognostic information. PAI‐1 concentration showed a positive correlation with advanced tumour stage (p = 0.008), but no significant correlation with nodal status (pN0: 2.6 vs. pN1: 4.0 ng/mg protein; p = 0.092). Using a cut‐off level of 2.4 ng/mg protein, patients with elevated PAI‐1 levels demonstrated reduced RFS (45.9 versus 52.9 months; p = 0.1). Multivariate analysis, including nodal status, tumour stage, lymphovascular space involvement and grading failed to demonstrate any prognostic impact of uPA and PAI‐1. Conclusions The results indicate, that PAI‐1 expression is of some prognostic impact in cervical cancer, indicating an association of elevated PAI levels with local tumour progression and reduced recurrence‐free survival. KW - Plasminogen human-Aktivator KW - Urokinase KW - squamöser Krebs KW - Gebärmutterhals Y1 - 2004 U6 - https://doi.org/10.1111/j.0004-8666.2002.00385.x VL - 42 IS - 4 SP - 385 EP - 388 ER - TY - CHAP A1 - Raptis, Georgios T1 - Ein Verfahren zur Lösung des Problems der kryptographischen Langzeitsicherheit medizinischer Daten, die in einer Infrastruktur gespeichert werden T2 - BIOSIG-Konferenz 2007, Darmstadt N2 - Medizinische Daten, die - wie derzeit für die Telematik-Infrastruktur nach §291a SGB V spe-zifiziert - auch außerhalb der physischen Kontrolle der Eigentümer oder Ersteller (also z.B. außerhalb von Arztpraxen oder Klinken) auf Servern kryptographisch verschlüsselt gespeichert werden, müssen sehr lange vertraulich bleiben. Insbesondere darf der technische Betreiber des Servers, der die Daten speichert, keinen Zugriff erlangen. Es kann jedoch keine verlässliche Aussage dahingehend getroffen werden, ob die heute eingesetzten kryp-tographischen Algorithmen in 30 oder 40 Jahren die Vertraulichkeit der medizinischen Daten weiterhin gewährleisten. Es wird ein Verfahren vorgestellt, welches das Problem der langfristigen Sicherheit von verschlüsselt gespeicherten medizinischen Daten aus kryptographischer Sicht löst. Die Anwendung des Verfahrens wird am Beispiel einer nach den derzeit bekannten gematik-Spezifikationen definierten Infrastruktur veranschaulicht. Es wird von einer getrennten Speicherung von verschlüsselten medizinischen Daten und Schlüsselmaterial ausgegangen. Die Daten werden an der Datenquelle (Konnektor, z.B. eines Arztes) mit einem Einmalblock (One Time Pad, OTP) verschlüsselt. Sie sind damit beweisbar sicher verschlüsselt, weil das One-Time-Pad-Verschlüsselungsverfahren beweisbar „perfekt geheim“ ist. Der OTP-Schlüssel wird mit einem symmetrischen Schlüssel verschlüsselt, der wiederum mit den asymmetrischen Schlüsseln aller Zugriffsberechtigten verschlüsselt wird. Die kryptographische, technische und organisatorische Sicherheit des Verfahrens sowie seine Voraussetzungen und Kosten werden analysiert. KW - Gesundheitsinformationssystem KW - Datensicherhung KW - Kryptologie Y1 - 2007 UR - http://www.baek.de/downloads/Raptis_Verfahren-2.pdf ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta T1 - Familial cancer history in patients with carcinoma of the cervix uteri JF - European Journal of Obstetrics & Gynecology and Reproductive Biology KW - Gebärmutterhalskrebs KW - Familienanamnese Y1 - 2002 U6 - https://doi.org/10.1016/s0301-2115(01)00520-6 VL - 101 IS - 1 SP - 54 EP - 57 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Fischer, Uta A1 - Hanel, C. A1 - Kuhn, H. A1 - Raptis, Georgios A1 - Bilek, Karin T1 - p53 in surgically treated and pathologically staged cervical cancer BT - correlation with local tumor progression, but not with lymphatic spread JF - Pathology - Research and Practice KW - Gebärmutterhalskrebs KW - Tumorsuppressor-Gen KW - Chirurgie KW - Histopathologie Y1 - 2001 VL - 197 IS - 9 SP - 605 EP - 609 ER - TY - JOUR A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Geßner, W. A1 - Roschlau, U. A1 - Dressel, K. A1 - Bilek, Karin A1 - Horn, Lars-Christian T1 - Epidemiologie und formale Pathogenese des Zervixkarzinoms JF - Zentralblatt für Gynäkologie T2 - Epidemiology and pathogenesis of cervical cancer KW - Gebärmutterhalskrebs KW - Epidemiologie KW - Pathogenese Y1 - 2001 VL - 123 IS - 4 SP - 198 EP - 205 ER - TY - CHAP A1 - Raptis, Georgios T1 - Die Konzepte und Mechanismen der elektronischen Gesundheitskarte und des Heilberufsausweises aus der Sicht der Datensicherheit / des Datenschutzes BT - Vortrag T2 - Forschungsseminar med. Informatik an der Universität Heidelberg, 22.06.2006 KW - Elektronische Gesundheitskarte KW - Heilberuf KW - Ausweis KW - Datenschutz KW - Datensicherheit Y1 - 2005 ER - TY - GEN A1 - Raptis, Georgios T1 - Ist die Sicherheit der medizinischen Daten in der Telematik-Infrastruktur zu gewährleisten? BT - Vortrag an der Universität Heidelberg, Kolloquium Wissenschaftlichkeit in der Medizin, 10.05.2007 T2 - Kolloquium Wissenschaftlichkeit in der Medizin, Universität Heidelberg, 10.05.2007 KW - Telemedizin KW - Datensicherheit Y1 - 2007 ER - TY - CHAP A1 - Markus Rütten, A1 - Krenkel, Lars A1 - Kessler, Roland T1 - Secondary Flow Effects as Physical Mechanism of Molecular Species Transport in Highly Oscillating Generic-Trachea Flows T2 - 83rd Annual Scientific Conference of the International Association of Applied Mathematics and Mechanics, 26.-30. März 2012, Darmstadt, Germany N2 - The high frequency oscillation artificial respiration technique is often the last hope for patients to survive highly damaged lung tissue. The mortality can significantly be reduced. In comparison to conventional artificial respiration the applied volume flow rate and pressure is significantly lowered in order to avoid further damaging of lung tissue and remaining intact alveolae. However, the physical mechanism of transport of oxygen to the aeriols under high frequency oscillation is not well understood. In the upper part of the lung convection is dominant, in contrast, the gas exchange in the lower parts of the lung is mainly driven by diffusion. It is not clear how associated gradients of concentrations of different molecular species are then achieved. Highly oscillating fluid flows has been a long research topic in fluid dynamics. It is known that oscillating pressure fluctuations are able to induce secondary flows, in particular, in curved ducts and pipes. The question is, whether the trachea enforces the generation of secondary flow by its kidney like cross section geometry. The influence of molecular species of different densities onto the formation of secondary flows and the convectional transport within the trachea is investigated. In order to clarify the physical mechanisms behind flow simulations have been conducted by using state of the art CFD techniques. KW - CFD KW - Generic-Trachea Flows Y1 - 2012 UR - https://elib.dlr.de/75733/ ER - TY - CHAP A1 - Friedrich, Janet A1 - Feldmann, Daniel A1 - Krenkel, Lars A1 - Wagner, Claus A1 - Schreiber, Laura Maria T1 - 19F Gas Flow Measurement of C3F7H During Constant Flow and High Frequency Oscillatory Ventilation T2 - Discovery, innovation & application - advancing mr for improved health : ISMRM 21st Annual Meeting & Exhibition ; SMRT 22nd Annual Meeting Salt Lake City, Utah, USA 20-26 April 2013 N2 - The aim of the current study is the development of MRI methods that enable the investigation of gas flow mechanisms during high frequency oscillatory ventilation. This work includes flow measurements during three constant flows (19.9, 30.6 and 41.4 L min-1) and the comparison to direct numerical simulations (DNS) using a second-order-acurate finite-volume method and to data measured with a volume flow meter. 19F-MRI, DNS and flow meter data are in good agreement. Flow measurements during HFOV of 4 Hz were successfully performed and velocity profiles could be recorded at different phases of the ventilation cycle. Y1 - 2013 UR - https://archive.ismrm.org/2013/1482.html VL - 21 ER -