Effects on the maternofetal unit of the rabbit model after substitution of the amniotic fluid with perfluorocarbons

Objectives: Exchanging amniotic fluid (AF) with perfluorocarbon (PFC) may serve as a medium for fetoscopic surgery. This study evaluates the distribution and physiologic effects of intraamniotic PFC as a medium for fetoscopy. Methods: Fetuses of 17 pregnant rabbits underwent either exchange of the AF with PFC, electrolyte solution (ES), or control. The quality of vision during fetoscopy was assessed in AF and PFC. After 6 h, we determined the distribution of PFC in the maternofetal unit. Results: Quality of vision during fetoscopy was better in PFC than with AF. There was no difference in fetal survival between the study groups. PFC was demonstrated on X-ray in the pharynx of 4 fetuses, and the esophagus in 1. Conclusions: PFC provided an ideal medium for fetoscopy without fetal compromise. Copyright (c) 2005 S. Karger AG, Basel

Prevalence and etiology of false normal aEEG recordings in neonatal hypoxic-ischaemic encephalopathy.

BACKGROUND: Amplitude-integrated electroencephalography (aEEG) is a useful tool to determine the severity of neonatal hypoxic-ischemic encephalopathy (HIE). Our aim was to assess the prevalence and study the origin of false normal aEEG recordings based on 85 aEEG recordings registered before six hours of age. METHODS: Raw EEG recordings were reevaluated retrospectively with Fourier analysis to identify and describe the frequency patterns of the raw EEG signal, in cases with inconsistent aEEG recordings and clinical symptoms. Power spectral density curves, power (P) and median frequency (MF) were determined using the raw EEG. In 7 patients non-depolarizing muscle relaxant (NDMR) exposure was found. The EEG sections were analyzed and compared before and after NDMR administration. RESULTS: The reevaluation found that the aEEG was truly normal in 4 neonates. In 3 neonates, high voltage electrocardiographic (ECG) artifacts were found with flat trace on raw EEG. High frequency component (HFC) was found as a cause of normal appearing aEEG in 10 neonates. HFC disappeared while P and MF decreased significantly upon NDMR administration in each observed case. CONCLUSION: Occurrence of false normal aEEG background pattern is relatively high in neonates with HIE and hypothermia. High frequency EEG artifacts suggestive of shivering were found to be the most common cause of false normal aEEG in hypothermic neonates while high voltage ECG artifacts are less common

Therapeutic hypothermia translates from ancient history in to practice

Acute postasphyxial encephalopathy around the time of birth remains a major cause of death and disability. The possibility that hypothermia may be able to prevent or lessen asphyxial brain injury is a “dream revisited”. In this review, a historical perspective is provided from the first reported use of therapeutic hypothermia for brain injuries in antiquity, to the present day. The first uncontrolled trials of cooling for resuscitation were reported more than 50 y ago. The seminal insight that led to the modern revival of studies of neuroprotection was that after profound asphyxia, many brain cells show initial recovery from the insult during a short “latent” phase, typically lasting ~6 h, only to die hours to days later during a “secondary” deterioration phase characterized by seizures, cytotoxic edema, and progressive failure of cerebral oxidative metabolism. Studies designed around this conceptual framework showed that mild hypothermia initiated as early as possible before the onset of secondary deterioration, and continued for a sufficient duration to allow the secondary deterioration to resolve, is associated with potent, long-lasting neuroprotection. There is now compelling evidence from randomized controlled trials that mild induced hypothermia significantly improves intact survival and neurodevelopmental outcomes to midchildhood

Fachlicher Abschlussbericht

Im Rahmen des Eigenforschungsvorhabens wurde eine umfassende strukturmechanische Analyse von Brennelementen, Brennstäben sowie Transport- und Lagerbehältern für Kernbrennstoffe unter Berücksichtigung vielfältiger realer Belastungsszenarien durchgeführt. Das zentrale Ziel bestand darin, das mechanische Verhalten und die Belastungsgrenzen dieser Komponenten bei Zwischenlagerung und anschließenden Handhabungsvorgängen zu bestimmen. Besonderes Augenmerk galt dabei Ereignissen wie einem Behälteraufprall aus 30 cm Höhe, die mittels Finite-Elemente-Methoden (FEM) modelliert und simuliert wurden. Im methodischen Ansatz wurden für sämtliche relevante Behälterkomponenten spezifische Randbedingungen und Parameter abgeleitet, um die Wirkungen von normalen Transportprozessen sowie von außergewöhnlichen Vorfällen (wie Unfällen oder Stürzen) umfassend abzubilden. Ein Schwerpunkt lag auf der Entwicklung und Validierung von Rechenmodellen, welche die komplexen geometrischen Strukturen, Materialeigenschaften und Interaktionsmechanismen im System realitätsnah erfassen. Die Modelle wurden iterativ optimiert und anhand von experimentellen Daten sowie Literaturwerten verifiziert. Die Simulationsergebnisse liefern belastbare Daten für die sicherheitstechnische Bewertung und schließen erste Wissenslücken bezüglich der Belastungszustände von Brennelementen nach verlängerter Zwischenlagerung. Insbesondere wurden kritische Lastfälle identifiziert, die als Grundlage für zukünftige Untersuchungen dienen können. Die Arbeit trägt somit entscheidend zur wissenschaftlichen Nachvollziehbarkeit und Dokumentation bei. Abschließend zeigt die Studie, dass die entwickelten Methoden und Modelle eine sorgfältige Bewertung der mechanischen Integrität von Brennstäben, Brennelementen und Behältersystemen in Zwischenlagern ermöglichen. Die Ergebnisse unterstreichen die Notwendigkeit, verschiedene Lastszenarien und die komplexe Systeminteraktion in die Sicherheitsbewertung einzubeziehen und bieten eine belastbare Grundlage für weiterführende Forschung im Bereich der Zwischenlagerung abgebrannter Brennelemente.Within the scope of this research project, a comprehensive structural-mechanical analysis of fuel assemblies, fuel rods, and transport and storage casks for nuclear fuel was conducted, taking into account a variety of realistic loading scenarios. The central objec tive was to determine the mechanical behavior and stress limits of these components during interim storage and subsequent handling operations. Particular attention was given to events such as a container impact from a height of 30 cm, which were modeled and simulated using finite element methods (FEM). Methodologically, specific boundary conditions and parameters were derived for all relevant components to comprehensively represent the effects of normal transport scenarios as well as handling incidents (e.g., accidents or drops). A key focus was the development and validation of computational models that realistically capture the complex geometrical structures, material properties, and interaction mechanisms within the system. The models were iteratively optimized and validated by comparison with experi mental data and literature values. The simulation results provide reliable data for safety assessments and close initial knowledge gaps regarding the stress states of fuel assemblies after extended interim storage. Critical load cases were identified that can serve as a basis for future studies. Consequently, this work makes a significant contribution to scientific transparency and documentation. In conclusion, the study demonstrates that the developed methods and models enable a thorough assessment of the mechanical integrity of fuel rods, fuel assemblies, and cask systems in interim storage facilities. The results emphasize the necessity of includ ing various load scenarios and the complex system interaction in safety evaluations and provide a sound foundation for further research in the field of interim storage of spent nuclear fuel

fachlicher Abschlussbericht

Fragen zur Strahlenexposition durch radioaktive Abfälle lassen sich grundsätzlich nur bei genauer Kenntnis der emittierten Dosisleistungen beantworten. Dabei spielen die Inventarcharakterisierung und die Abschirmwirkung des Behälters eine Schlüsselrolle bei der Festlegung geeigneter Randbedingungen, beispielsweise für besondere Anordnungen in Zwischenlagern oder für spezifische Transportanforderungen. Die GRS verfügt über die notwendigen Programme und Expertisen zur wissenschaftlichen Bewertung sicherheitsrelevanter Fragen im Zusammenhang mit Zwischenlagerung und Transport. Dieses Eigenforschungsvorhaben wurde initiiert, um die Berechnungskette für die Inventarcharakterisierung und Dosisberechnung schwach- (LAW), mittel- (MAW) und hochradioaktiver Abfälle (HAW) zu modernisieren. Zu diesem Zweck wurde die bestehende Methode überprüft und es wurde ein neues aktualisiertes Konzept entwickelt. Dies umfasst die verwendeten Programme und -methoden in den Bereichen Inventarbestimmung, Aktivierungs- und Abschirmberechnungen sowie deren Schnittstellen. Die neue Rechenkette, gesteuert über die Anwendung WANIRAS, umfasst moderne Berechnungscodes und -methoden, um zuverlässige Vorhersagen über die radiologischen Auswirkungen von Transport und Lagerung von LAW/MAW und HAW zu ermöglichen, die dann für Sicherheitsplanungen und -bewertungen genutzt werden können. Der aktu-elle Stand von WANIRAS, umfasst Grundfunktionen der Berechnungskette: Inventarbe-rechnung und Strahlungsfeldberechnung. WANIRAS besteht aus einer grafischen Ober-fläche, die der Inputerstellung diverser Rechenprogramme sowie deren Nachbereitung und Schnittstellen dient. Die Identifizierung repräsentativer Rechenfälle, eine zentrale Aufgabe des Eigenforschungsvorhabens, sowie die Neubewertung und teilweise Erneuerung der verwendeten Software erlaubte es, den Informationstransfer zwischen den Berechnungsschritten zu überarbeiten. Diese Rechenfälle wurden außerdem dazu genutzt, die Kompatibilität mit den früher genutzten Rechenmethoden zu überprüfen. Die Ergebnisse der repräsentativen Rechenfälle, gesteuert durch die entwickelte Anwendung WANIRAS, und der alten Rechenkette stimmen gut überein. Eventuelle Abweichungen konnten durch Anpassung der verwendeten Verfahren und Bibliotheken zufriedenstellend erklärt werden. In WANIRAS und der begleitenden Dokumentation sind außerdem Beispiele, Leitfäden und unterstützende Werkzeuge implementiert, die auch unerfahrenen Modellierern die Berechnung und Bewertung von Standardproblemen im deutschen Abfallmanagement ermöglichen sollen. Die Bereitstellung einer erweiterbaren Struktur durch die Software WANIRAS, in welcher Wissen und Methoden gebündelt sind, gewährleistet zudem Konsistenz bei Auswertungen und Bewertungen über den Erfahrungsstand einzelner Gutachter hinaus. Darüber hinaus bietet sie einen erweiterbaren Rahmen für den Aufbau weiterer Methoden zur Dosis- und Inventarbewertung, wie beispielsweise die Einbeziehung anderer Transportcodes, sowie eine robuste Methode für Wissensmanagement und -transfer im Bereich der Strahlentransportmodellierung.Questions about radiation exposure from radioactive waste can generally only be an swered with precise knowledge of the emitted dose rates. Inventory characterization and the shielding effect of the storage container play a key role in determining suitable bound ary conditions, for example, for special arrangements in storage facilities or for specific transport requirements. GRS has the necessary software and expertise for the scientific evaluation of safety relevant issues related to nuclear waste storage and transport. This research project was initiated to modernize the calculation chain for inventory characterization and dose cal culations for low-level (LAW), intermediate-level (MAW), and high-level radioactive waste (HAW). For this purpose, the existing method was reviewed, and a new, updated concept was developed. This includes the programs and methods used in the areas of inventory determination, activation and shielding calculations, and their interfaces. The new calculation chain, controlled by the WANIRAS application, includes modern calculation codes and methods to enable reliable predictions of the radiological impacts of transport and storage of LAW/MAW and HAW, which can then be used for safety planning and assessments. The current status of WANIRAS includes basic functions of the calculation chain: inventory calculation and radiation field calculation. WANIRAS con sists of a graphical interface used for input generation of various calculation programs, as well as data post-processing and interfaces between calculation codes. The identification of representative calculation cases, a central task of the project, as well as the re-evaluation and partial renewal of the software used, made it possible to revise the information transfer between the calculation steps. These calculation cases were also used to verify compatibility with the previously used calculation methods. The results of the representative calculation cases, controlled by the developed WANIRAS applica tion, and the previous calculation chain are in good agreement. Any deviations could be satisfactorily explained by adapting the methods and libraries used. WANIRAS and the accompanying documentation also contain examples, guidelines, and supporting tools designed to enable even inexperienced modelers to calculate and evaluate standard problems relevant to German waste management. The WANIRAS software's provision of an expandable structure, in which knowledge and methods are bundled, also ensures consistency in evaluations and assessments beyond the IV experience level of individual experts. Furthermore, it offers a modular framework for developing additional methods for dose and inventory assessment, such as the inclusion of other transport codes, as well as a robust method for knowledge management and transfer in the field of radiation transport modeling

Effect of exogenous surfactants on viability and DNA synthesis in A549, immortalized mouse type II and isolated rat alveolar type II cells

<p>Abstract</p> <p>Background</p> <p>In mechanically ventilated preterm infants with respiratory distress syndrome (RDS), exogenous surfactant application has been demonstrated both to decrease DNA-synthesis but also and paradoxically to increase epithelial cell proliferation. However, the effect of exogenous surfactant has not been studied directly on alveolar type II cells (ATII cells), a key cell type responsible for alveolar function and repair.</p> <p>Objective</p> <p>The aim of this study was to investigate the effects of two commercially available surfactant preparations on ATII cell viability and DNA synthesis.</p> <p>Methods</p> <p>Curosurf^®and Alveofact^®were applied to two ATII cell lines (human A549 and mouse iMATII cells) and to primary rat ATII cells for periods of up to 24 h. Cell viability was measured using the redox indicator resazurin and DNA synthesis was measured using BrdU incorporation.</p> <p>Results</p> <p>Curosurf^®resulted in slightly decreased cell viability in all cell culture models. However, DNA synthesis was increased in A549 and rat ATII cells but decreased in iMATII cells. Alveofact^®exhibited the opposite effects on A549 cells and had very mild effects on the other two cell models.</p> <p>Conclusion</p> <p>This study showed that commercially available exogenous surfactants used to treat preterm infants with RDS can have profound effects on cell viability and DNA synthesis.</p

Lung recruitment and endotracheal suction in ventilated preterm infants measured with electrical impedance tomography

Aims Although suctioning is a standard airway maintenance procedure, there are significant associated risks, such as loss of lung volume due to high negative suction pressures. This study aims to assess the extent and duration of change in end-expiratory level (EEL) resulting from endotracheal tube (ETT) suction and to examine the relationship between EEL and regional lung ventilation in ventilated preterm infants with respiratory distress syndrome. Methods A prospective observational clinical study of the effect of ETT suction on 20 non-muscle-relaxed preterm infants with respiratory distress syndrome (RDS) on conventional mechanical ventilation was conducted in a neonatal intensive care unit. Ventilation distribution was measured with regional impedance amplitudes and EEL using electrical impedance tomography. Results ETT suction resulted in a significant increase in EEL post-suction (P < 0.01). Regionally, anterior EEL decreased and posterior EEL increased post-suction, suggesting heterogeneity. Tidal volume was significantly lower in volume-guarantee ventilation compared with pressure-controlled ventilation (P = 0.04). Conclusions ETT suction in non-muscle-relaxed and ventilated preterm infants with RDS results in significant lung volume increase that is maintained for at least 90 min. Regional differences in distribution of ventilation with ETT suction suggest that the behaviour of the lung is heterogeneous in nature