Untersuchungen zur Stabilisierung und Miniaturisierung kationensensitiver Schichten für die Entwicklung von optochemischen Mikrosensoren

Im Rahmen der vorliegenden Arbeit wurden optochemische Sensoren (Optroden) zur Detektion der kationischen Spezies Quecksilber(II), Calcium(II) und zur Bestimmung von pH-Werten entwickelt und miniaturisiert. Der erste thematische Schwerpunkt der Arbeit widmet sich der Verbesserung der Stabilität von kationensensitiven Rezeptorschichten. Werden diese durch einfache Einkapselung von Indikatoren hergestellt, so wird die Stabilität der Schicht bedingt durch das Auswaschen des Farbstoffes auf etwa einen Tag begrenzt. Zur Unterdrückung dieses Farbstoffaustrages wurde eine neue Immobilisierungsmethode entwickelt und erprobt, die in der kovalenten Anbindung von Fluoreszenzindikatoren an das wasserlösliche Polysaccharid Dextran (70.000 g/mol) und der anschließenden Einkapselung der makromolekular gebundenen Indikatormoleküle in hydrophilen Matrices besteht. Als Matrices wurden anorganische Silikagele, die nach dem Sol-Gel-Verfahren hergestellt wurden, und das organische Hydrogel Polyhydroxyethylmethacrylat (PolyHEMA) eingesetzt. Die vorgestellte Immobilisierungsmethode weist gegenüber der direkten kovalenten Anbindung des Indikators an die Matrix eine deutlich erhöhte Flexibilität auf, was beispielhaft an drei Analyt-Rezeptor-Paaren dargestellt wird. Zur Herstellung von Quecksilber-sensitiven Schichten wurden zunächst Porphyrin-Dextrane synthetisiert und mittels spektroskopischer Methoden sowie durch Elektrophorese charakterisiert. Porphyrin-Dextran-dotierte, mesoporöse Silikagel- Schichten zeigten nach 40tägiger Lagerung in Meßpuffer noch 92% der anfänglichen Fluoreszenzintensität. Auf der Basis von Fluorescein-Dextran wurden pH-sensitive Silikagel- und PolyHEMA-Schichten hergestellt. Letztere zeigten einen Meßbereich von pH 5 bis 8 und Ansprechzeiten von 5 Sekunden/pH. Nach 18tägiger Lagerung in Meßpuffer zeigten die Sensoren noch über 95% der ursprünglichen Fluoreszenzintensitäten. Durch Coimmobilisierung von Calcium Green-Dextran und Texas Red-Dextran wurde ein Calcium-sensitiver Sensor mit interner Referenz hergestellt. Der Meßbereich des Sensors liegt zwischen 5  10-8 und 10-5 mol/l Ca(II) bei Ansprechzeiten von 5 Sekunden bis zum Erreichen des Sättigungswertes. Der Sensor erwies sich als sehr selektiv gegenüber Interferenzen von Na(I), K(I) und Mg(II). Durch die interne Referenzierung des Meßsignals läßt sich die Reproduzierbarkeit der Sensorsignale entscheidend verbessern. Als zweiter Schwerpunkt der Arbeit wurde in mehreren Schritten die Miniaturisierung der Calciumsensoren mit interner Referenz vorgenommen. Unter Verwendung von optischer Fasertechnik wurden Mikrosensoren mit Durchmessern von 600 bzw. 50 µm entwickelt. Basierend auf verjüngten Faserspitzen (Taper) mit Durchmessern von etwa 300 nm wurden die derzeit kleinsten faseroptischen Calciumsensoren (Nanosensoren) erhalten. Aufgrund der verbesserten Stabilität und der extremen Miniaturisierung der vorgestellten optischen Sensoren lassen sich in Zukunft neue analytische Aufgabenstellungen (z.B. Messung in biologischen Zellen) mit einer Ortsauflösung im Nanometerbereich bearbeiten

Depth of anesthesia by Narcotrend® and postoperative characteristics in children undergoing cardiac surgery under extracorporeal circulation: a retrospective comparison of two anesthetic regimens

Background: Depth of anesthesia may be insufficient in pediatric cardiac anesthesia if a total intravenous anesthetic regimen with opioids and midazolam is used during cardiopulmonary bypass. The advantages of sevoflurane-based balanced anesthesia may be (1) a more graduated regulation of the depth of anesthesia during cardiopulmonary bypass and (2) a reduction in postoperative ventilation time for children in comparison with total intravenous anesthesia. Aim: To evaluate a possibly positive effect of sevoflurane-based balanced anesthesia in children undergoing cardiac surgery we analyzed whether this anesthetic regimen had a significant effect related to (1) depth of anesthesia, (2) the need for opioids during cardiopulmonary bypass as well as on postoperative characteristics such as (3) time of postoperative ventilation, and (4) duration of stay in the intensive care unit in comparison with total intravenous anesthesia. Methods: In a retrospective analysis, data from heart-lung machine protocols from 2013 to 2016 were compared according to anesthetic regimen (sevoflurane-balanced anesthesia, n = 70 vs. total intravenous anesthesia, n = 65). Children (age: 8 weeks to 14 years) undergoing cardiac surgery with cardiopulmonary bypass were included. As a primary outcome measure, we compared Narcotrend® system–extracted data to detect insufficient phases of anesthetic depth during extracorporeal circulation under moderate hypothermia. Postoperatively, we measured the postoperative ventilation time and the number of days in the intensive care unit. Furthermore, we analyzed patients’ specific characteristics such as opioid consumption during cardiopulmonary bypass. Regression analysis relating primary objectives was done using the following variables: anesthetic regimen, age, severity of illness/surgery, and cumulative dosage of opiates during cardiopulmonary bypass. Results: No significant differences were observed in descriptive patient characteristics (age, body weight, height, and body temperature) between the two groups. Further, no significant differences were found in depth of anesthesia by analyzing phases of superficial B1-C2-electroencephalography Narcotrend® data. No marked difference between the groups was observed for the duration of postoperative intensive care unit stay. However, the postoperative ventilation time (median (95% CI, hours)) was significantly lower in the sevoflurane-based balanced anesthesia group (6.0 (2.0-15.0)) than in the total intravenous anesthesia group (13.5 (7.0-25)). A higher dosage of opioids and midazolam was required in the total intravenous anesthesia group to maintain adequate anesthesia during cardiopulmonary bypass. Regression analysis showed an additional, significant impact of the following factors: severity of illness and severity grade of cardiac surgery (according to Aristotle) on the primary endpoint. Conclusion: In children undergoing cardiac surgery in our department, the use of sevoflurane-balanced anesthesia during cardiopulmonary bypass showed no superiority of inhalational agents over total intravenous anesthesia with opioids and benzodiazepines preventing phases of superficial anesthesia, but a marked advantage for the postoperative ventilation time compared with total intravenous anesthesia

Acupuncture to improve tolerance of diagnostic esophagogastroduodenoscopy in patients without systemic sedation: results of a single-center, double-blinded, randomized controlled trial (DRKS00000164)

Background: Sedation prior to esophagogastroduodenoscopy is widespread and increases patient comfort. However, it demands additional trained personnel, accounts for up to 40% of total endoscopy costs and impedes rapid hospital discharge. Most patients lose at least one day of work. 98% of all serious adverse events occurring during esophagogastroduodenoscopy are ascribed to sedation. Acupuncture is reported to be effective as a supportive intervention for gastrointestinal endoscopy, similar to conventional premedication. We investigated whether acupuncture during elective diagnostic esophagogastroduodenoscopy could increase the comfort of patients refusing systemic sedation. Methods: We performed a single-center, double-blinded, placebo-controlled superiority trial to compare the success rates of elective diagnostic esophagogastroduodenoscopies using real and placebo acupuncture. All patients aged 18 years or older scheduled for elective, diagnostic esophagogastroduodenoscopy who refused systemic sedation were eligible; 354 patients were randomized. The primary endpoint measure was the rate of successful esophagogastroduodenoscopies. The intervention was real or placebo acupuncture before and during esophagogastroduodenoscopy. Successful esophagogastroduodenoscopy was based on a composite score of patient satisfaction with the procedure on a Likert scale as well as quality of examination, as assessed by the examiner. Results: From February 2010 to July 2012, 678 patients were screened; 354 were included in the study. Baseline characteristics of the two groups showed a similar distribution in all but one parameter: more current smokers were allocated to the placebo group. The intention-to-treat analysis included 177 randomized patients in each group. Endoscopy could successfully be performed in 130 patients (73.5%) in the real acupuncture group and 129 patients (72.9%) in the placebo group. Willingness to repeat the procedure under the same conditions was 86.9% in the real acupuncture group and 87.6% in the placebo acupuncture group. Conclusions: Esophagogastroduodenoscopy without sedation is safe and can successfully be performed in two-thirds of patients. Patients planned for elective esophagogastroduodenoscopy without sedation do not benefit from acupuncture of the Sinarteria respondens (Rs) 24 Chengjiang middle line, Pericard (Pc) 6 Neiguan bilateral, or Dickdarm (IC) 4 Hegu bilateral, according to traditional Chinese medicine meridian theory. Trial registration DRKS00000164. Registered on 10 December 2009

A New Technique for the Calculation and 3D Visualisation of Magnetic Complexities on Solar Satellite Images

YesIn this paper, we introduce two novel models for processing real-life satellite images to quantify and then visualise their magnetic structures in 3D. We believe this multidisciplinary work is a real convergence between image processing, 3D visualization and solar physics. The first model aims to calculate the value of the magnetic complexity in active regions and the solar disk. A series of experiments are carried out using this model and a relationship has been indentified between the calculated magnetic complexity values and solar flare events. The second model aims to visualise the calculated magnetic complexities in 3D colour maps in order to identify the locations of eruptive regions on the Sun. Both models demonstrate promising results and they can be potentially used in the fields of solar imaging, space weather and solar flare prediction and forecasting

BepiColombo Science Investigations During Cruise and Flybys at the Earth, Venus and Mercury

The dual spacecraft mission BepiColombo is the first joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet Mercury. BepiColombo was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, and a sunshield. BepiColombo cruise trajectory is a long journey into the inner heliosphere, and it includes one flyby of the Earth (in April 2020), two of Venus (in October 2020 and August 2021), and six of Mercury (starting from 2021), before orbit insertion in December 2025. A big part of the mission instruments will be fully operational during the mission cruise phase, allowing unprecedented investigation of the different environments that will encounter during the 7-years long cruise. The present paper reviews all the planetary flybys and some interesting cruise configurations. Additional scientific research that will emerge in the coming years is also discussed, including the instruments that can contribute