Dynamics of the cold surface layer of polythermal Storglaciären, Sweden

Polythermal glaciers, i.e. glaciers with a combination of ice at and below the freezing point, are widespread in arctic and subarctic environments. The polythermal structure has major implications for glacier hydrology, ice flow and glacial erosion. However, the interplay of factors governing its spatial and temporal variations such as net mass balance, ice advection and water content in the ice is poorly investigated and as yet not fully understood. This study deals with a thorough investigation of the polythermal regime on Storglaciären, northern Sweden, a small valley glacier with a cold surface layer in the ablation area. Extensive field work was performed including mapping of the cold surface layer using ground-penetrating radar, ice temperature measurements, mass balance and ice velocity measurements. Analyses of these data combined with numerical modelling were used specifically to investigate the spatial and temporal variability of the cold surface layer, the spatial distribution of the water content just below the cold surface layer transition, the effect of radar frequency on the detection of the surface layer, and the sensitivity of the cold surface layer to changes in forcing. A comparison between direct temperature measurements in boreholes and ground-penetrating surveys shows that the radar-inferred cold-temperate transition depth is within ±1 m from the melting point of ice at frequencies above ~300 MHz. At frequencies below ~155 MHz, the accuracy degrades because of reduced scattering efficiency that occurs when the scatterers become much smaller compared to the wavelength. The mapped spatial pattern of the englacial cold-temperate transition boundary is complex. This pattern reflects the observed spatial variation in net loss of ice at the surface by ablation and vertical advection of ice, which is suggested to provide the predominant forcing of the cold surface layer thickness pattern. This is further supported by thermomechanical modeling of the cold surface layer, which indicates high sensitivity of the cold surface layer thickness to changes in vertical advection rates. The water content is the least investigated quantity that is relevant for the thermal regime of glaciers, but also the most difficult to assess. Spatial variability of absolute water content in the temperate ice immediately below the cold surface layer on Storglaciären was determined by combining relative estimates of water content from ground-penetrating radar data with absolute determination from temperature measurements and the thermal boundary condition at the freezing front. These measurements indicate large-scale spatial variability in the water content, which seems to arise from variations in entrapment of water at the firn-ice transition. However, this variability cannot alone explain the spatial pattern in the thermal regime on Storglaciären. Repeated surveys of the cold surface layer show a 22% average thinning of the cold surface layer on Storglaciären between 1989 and 2001. Transient thermomechanical modeling results suggest that the cold surface layer adapts to new equilibrium conditions in only a few decades after a perturbation in the forcing is introduced. An increased winter air temperature since mid-1980s seems to be the cause of the observed thinning of the cold surface layer. Over the last decades, mass balance measurements indicate that the glacier has been close to a steady state. The quasi-steady state situation is also reflected in the vertical advection, which shows no significant changes during the last decades. Increased winter temperatures at the ice surface would result in a slow-down of the formation of cold ice at the base of the cold surface layer and lead to a larger imbalance between net loss of ice at the surface and freezing of temperate ice at the cold-temperate transition.

Simulations of glacial/interglacial cycles with simple box-models. The ocean CO2 source during deglaciations

Máster en Oceanografía

Revisione critica dei risultati e nuovi algoritmi decisionali sulla chirurgia dell'OSAS

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is the periodic reduction or cessation of airflow during sleep. The syndrome is associated whit loud snoring, disrupted sleep and observed apnoeas. Surgery aims to alleviate symptoms of daytime sleepiness, improve quality of life and reduce the signs of sleep apnoea recordered by polysomnography. Surgical intervention for snoring and OSAHS includes several procedures, each designed to increase the patency of the upper airway. Procedures addressing nasal obstruction include septoplasty, turbinectomy, and radiofrequency ablation (RF) of the turbinates. Surgical procedures to reduce soft palate redundancy include uvulopalatopharyngoplasty with or without tonsillectomy, uvulopalatal flap, laser-assisted uvulopalatoplasty, and RF of the soft palate. More significant, however, particularly in cases of severe OSA, is hypopharyngeal or retrolingual obstruction related to an enlarged tongue, or more commonly due to maxillomandibular deficiency. Surgeries in these cases are aimed at reducing the bulk of the tongue base or providing more space for the tongue in the oropharynx so as to limit posterior collapse during sleep. These procedures include tongue-base suspension, genioglossal advancement, hyoid suspension, lingualplasty, and maxillomandibular advancement. We reviewed 269 patients undergoing to osas surgery at the ENT Department of Forlì Hospital in the last decade. Surgery was considered a success if the postoperative apnea/hypopnea index (AHI) was less than 20/h. According to the results, we have developed surgical decisional algorithms with the aims to optimize the success of these procedures by identifying proper candidates for surgery and the most appropriate surgical techniques. Although not without risks and not as predictable as positive airway pressure therapy, surgery remains an important treatment option for patients with obstructive sleep apnea (OSA), particularly for those who have failed or cannot tolerate positive airway pressure therapy. Successful surgery depends on proper patient selection, proper procedure selection, and experience of the surgeon. The intended purpose of medical algorithms is to improve and standardize decisions made in the delivery of medical care, assist in standardizing selection and application of treatment regimens, to reduce potential introduction of errors. Nasal Continuous Positive Airway Pressure (nCPAP) is the recommended therapy for patients with moderate to severe OSAS. Unfortunately this treatment is not accepted by some patient, appears to be poorly tolerated in a not neglible number of subjects, and the compliance may be critical, especially in the long term if correctly evaluated with interview as well with CPAP smart cards analysis. Among the alternative options in Literature, surgery is a long time honoured solution. However until now no clear scientific evidence exists that surgery can be considered a really effective option in OSAHS management. We have design a randomized prospective study comparing MMA and a ventilatory device (Autotitrating Positive Airways Pressure – APAP) in order to understand the real effectiveness of surgery in the management of moderate to severe OSAS. Fifty consecutive previously full informed patients suffering from severe OSAHS were enrolled and randomised into a conservative (APAP) or surgical (MMA) arm. Demographic, biometric, PSG and ESS profiles of the two group were statistically not significantly different. One year after surgery or continuous APAP treatment both groups showed a remarkable improvement of mean AHI and ESS; the degree of improvement was not statistically different. Provided the relatively small sample of studied subjects and the relatively short time of follow up, MMA proved to be in our adult and severe OSAHS patients group a valuable alternative therapeutical tool with a success rate not inferior to APAP.

Dati geochimici ed ecologici di foraminiferi planctonici. Implicazioni paleoceanografiche in due aree chiave: Oceano Meridionale e Mare Mediterraneo.

La studio della distribuzione spaziale e temporale della associazioni a foraminiferi planctonici, campionati in zone con differente regime idrografico, ha permesso di comprendere che molte specie possono essere diagnostiche della presenza di diverse masse d’acqua superficiali e sottosuperficiali e di diversi regimi di nutrienti nelle acque oceaniche. Parte di questo lavoro di tesi si basa sullo studio delle associazioni a foraminiferi planctonici attualmente viventi nel Settore Pacifico dell’Oceano Meridionale (Mare di Ross e Zona del Fronte Polare) e nel Mare Mediterraneo (Mar Tirreno Meridionale). L’obiettivo di questo studio è quello di comprendere i fattori (temperatura, salinità, nutrienti etc.) che determinano la distribuzione attuale delle diverse specie al fine di valutarne il valore di “indicatori” (proxies) utili alla ricostruzione degli scenari paleoclimatici e paleoceanografici succedutisi in queste aree. I risultati documentano che la distribuzione delle diverse specie, il numero di individui e le variazioni nella morfologia di alcuni taxa sono correlate alle caratteristiche chimico-fisiche della colonna e alla disponibilità di nutrienti e di clorofilla. La seconda parte del lavoro di tesi ha previsto l’analisi degli isotopi stabili dell’ossigeno e del rapporto Mg/Ca in gusci di N. pachyderma (sin) prelevati da pescate di micro zooplancton (per tarare l’equazione di paleo temperatura) da un box core e da una carota provenienti dalla zona del Fronte Polare (Oceano Pacifico meridionale), al fine di ricostruire le variazioni di temperatura negli ultimi 13 ka e durante la Mid-Pleistocene Revolution. Le temperature, dedotte tramite i valori degli isotopi stabili dell’ossigeno, sono coerenti con le temperature attuali documentate in questa zona e il trend di temperatura è paragonabile a quelli riportati in letteratura anche per eventi climatici come lo Younger Dryas e il mid-Holocene Optimum. I valori del rapporto Mg/Ca misurato tramite due diverse tecniche di analisi (laser ablation e analisi in soluzione) sono risultati sempre molto più alti dei valori riportati in letteratura per la stessa specie. La laser ablation sembra carente dal punto di vista del cleaning del campione e da questo studio emerge che le due tecniche non sono comparabili e che non possono essere usate indifferentemente sullo stesso campione. Per quanto riguarda l’analisi dei campioni in soluzione è stato migliorato il protocollo di cleaning per il trattamento di campioni antartici, che ha permesso di ottenere valori veritieri e utili ai fini delle ricostruzioni di paleotemperatura. Tuttavia, rimane verosimile l’ipotesi che in ambienti particolari come questo, con salinità e temperature molto basse, l’incorporazione del Mg all’interno del guscio risenta delle condizioni particolari e che non segua quindi la relazione esponenziale con la temperatura ampiamente dimostrata ad altre latitudini.

Development and characterization of non-oxide ceramic composites for mechanical and tribological applications

The main reasons for the attention focused on ceramics as possible structural materials are their wear resistance and the ability to operate with limited oxidation and ablation at temperatures above 2000°C. Hence, this work is devoted to the study of two classes of materials which can satisfy these requirements: silicon carbide -based ceramics (SiC) for wear applications and borides and carbides of transition metals for ultra-high temperatures applications (UHTCs). SiC-based materials: Silicon carbide is a hard ceramic, which finds applications in many industrial sectors, from heat production, to automotive engineering and metals processing. In view of new fields of uses, SiC-based ceramics were produced with addition of 10-30 vol% of MoSi2, in order to obtain electro conductive ceramics. MoSi2, indeed, is an intermetallic compound which possesses high temperature oxidation resistance, high electrical conductivity (21·10-6 Ω·cm), relatively low density (6.31 g/cm3), high melting point (2030°C) and high stiffness (440 GPa). The SiC-based ceramics were hot pressed at 1900°C with addition of Al2O3-Y2O3 or Y2O3-AlN as sintering additives. The microstructure of the composites and of the reference materials, SiC and MoSi2, were studied by means of conventional analytical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (SEM-EDS). The composites showed a homogeneous microstructure, with good dispersion of the secondary phases and low residual porosity. The following thermo-mechanical properties of the SiC-based materials were measured: Vickers hardness (HV), Young’s modulus (E), fracture toughness (KIc) and room to high temperature flexural strength (σ). The mechanical properties of the composites were compared to those of two monolithic SiC and MoSi2 materials and resulted in a higher stiffness, fracture toughness and slightly higher flexural resistance. Tribological tests were also performed in two configurations disco-on-pin and slideron cylinder, aiming at studying the wear behaviour of SiC-MoSi2 composites with Al2O3 as counterfacing materials. The tests pointed out that the addition of MoSi2 was detrimental owing to a lower hardness in comparison with the pure SiC matrix. On the contrary, electrical measurements revealed that the addition of 30 vol% of MoSi2, rendered the composite electroconductive, lowering the electrical resistance of three orders of magnitude. Ultra High Temperature Ceramics: Carbides, borides and nitrides of transition metals (Ti, Zr, Hf, Ta, Nb, Mo) possess very high melting points and interesting engineering properties, such as high hardness (20-25 GPa), high stiffness (400-500 GPa), flexural strengths which remain unaltered from room temperature to 1500°C and excellent corrosion resistance in aggressive environment. All these properties place the UHTCs as potential candidates for the development of manoeuvrable hypersonic flight vehicles with sharp leading edges. To this scope Zr- and Hf- carbide and boride materials were produced with addition of 5-20 vol% of MoSi2. This secondary phase enabled the achievement of full dense composites at temperature lower than 2000°C and without the application of pressure. Besides the conventional microstructure analyses XRD and SEM-EDS, transmission electron microscopy (TEM) was employed to explore the microstructure on a small length scale to disclose the effective densification mechanisms. A thorough literature analysis revealed that neither detailed TEM work nor reports on densification mechanisms are available for this class of materials, which however are essential to optimize the sintering aids utilized and the processing parameters applied. Microstructural analyses, along with thermodynamics and crystallographic considerations, led to disclose of the effective role of MoSi2 during sintering of Zrand Hf- carbides and borides. Among the investigated mechanical properties (HV, E, KIc, σ from room temperature to 1500°C), the high temperature flexural strength was improved due to the protective and sealing effect of a silica-based glassy phase, especially for the borides. Nanoindentation tests were also performed on HfC-MoSi2 composites in order to extract hardness and elastic modulus of the single phases. Finally, arc jet tests on HfC- and HfB2-based composites confirmed the excellent oxidation behaviour of these materials under temperature exceeding 2000°C; no cracking or spallation occurred and the modified layer was only 80-90 μm thick.

Geological evolution of the Monte Rosa

Eine detaillierte geochemische und geochronologische Studie an Gesteinen der Monte Rosa Decke (MR; Westalpen) wurde durchgeführt. Die MR wurde während der alpinen Orogenese zunächst eklogitfaziell und nachfolgend grünschieferfaziell überprägt.Eine detaillierte U-Pb geochronologische Studie an Zirkonen und Monaziten des MR Granits ergab ein Permisches Intrusionsalter (270 ± 4 Ma). Der MR Granit gehört zu den post-variszischen magmatischen Einheiten, welche die Instabilität der variszischen kontinentalen Kruste andeuten. Für die MR kann eine paläogeographische Position als Teil der 'Briançonnais-Schwelle' angenommen werden.Innerhalb des MR Granits treten Talk-Kyanit-Chloritoid-Gesteine ('Weißschiefer') auf. Diese stellen wesentliche Indikatoren für eine alpine Hochdruckmetamorphose in der MR dar. Massenbilanzberechnungen wurden durchgeführt, um den Massentransfer zu quantifizieren, welcher für die Bildung eines Weißschiefers aus einem granitischen Protolith notwendig ist. Ein Modell für die Entwicklung der Weißschiefer wurde entwickelt.Es wurde eine in-situ 40Ar/39Ar UV-Laser-Ablationsstudie an Hellglimmern der alpinen Mineralparagenese durchgeführt. Sie ergab eine heterogene Altersverteilung. Diese Alter können durch Glimmerrekristallisation unter relativ 'trockenen' hochdruckmetamorphen Bedingungen begleitet von partiellem Verlust von radiogenem Argon während der alpinen Metamorphose erklärt werden. Eine ähnlich komplexe Entwicklung mit partieller Homogenisierung des Isotopensystems kann in der Strontium-Isotopie beobachtet werden. Diese Isotopenstudien liefern Hinweise auf das Schließverhalten von Isotopensystemen unter hochdruckmetamorphen Bedingungen.

Ansatz zur Etablierung von konditional/reversiblen knock-out Mäusen für das zellspezifische T-Zell Onkogen SCL

Ziel der vorliegenden Arbeit war es, ein innovatives System zur Herstellung einer konditional/reversiblen SCL-knock-out Maus zu etablieren. Es wurde deshalb ein neuer knock-in/knock-out Ansatz mit Hilfe des Tet-Systems gewählt. Im Rahmen dieser Arbeit war es möglich für die Generierung der konditionalen SCL-knock-out Maus essentielle Effektor- und Respondermauslinien zu etablieren und zu charakterisieren. Durch knock-in der rtTA-cDNA in den SCL-Lokus wurde eine Effektormauslinie hergestellt, welche in allen untersuchten hämatopoietischen Geweben rtTA exprimierte.Die zur Generierung der SCL-knock-out Maus notwendigen transgenen Responderlinien wurden ebenfalls generiert. Diese Linien wurden in einem Funktionsassay auf ihre Regulierbarkeit rekombinanter SCL-Expression untersucht. Dabei wurde eine Linie identifiziert, welche stringent/exogen regulierbar war.Effektor- und Responderlinie konnten etabliert und durch adäquate Kreuzung eine heterozygote Effektor/Responderlinie generiert werden. Die Rückkreuzung dieser Linie bei gleichzeitiger Gabe von DOX sollte in der konditionalen/reversiblen SCL-knock-out Maus resultieren. Bei Ende dieser Arbeit wurde allerdings in keinem Fall ein Rescue des letalen SCL Nullhintergrunds durch die rtTA-vermittelte rekombinante SCL-Expression beobachtet. Die in dieser Arbeit bereits hergestellten und verbesserten neuen Effektorkonstrukte sowie das Zurückgreifen auf alle vorhandenen SCL-Respondermäuse können in Zukunft zur erfolgreichen Etablierung eines exogen regulierbaren konditional/reversiblen SCL knock-out führen.

Entwicklung und Validierung einer massenspektrometrischen Isotopenverdünnungsanalyse zur direkten Multielementbestimmung in pulverförmigen Proben mittels LA-ICP-MS

In dieser Arbeit wurde erstmalig eine massenspektrometrische Isotopenverdünnungsanalyse (MSIVA) als Quantifizierungsmethode für die Multielementbestimmung in pulverförmigen Proben mittels Laserablations-induktiv gekoppelter Plasma-Massenspektrometrie (LA-ICP-MS) entwickelt. Diese LA-ICP-MSIVA wurde zur Bestimmung von Elementspuren in optisch-reinem Calciumfluorid eingesetzt und anhand der Analyse mehrerer zertifizierter Referenzmaterialien unterschiedlicher Matrixzusammensetzung validiert.Mit den in dieser Arbeit entwickelten direkten LA-ICP-MS-Analysenmethoden dürfte es in der Zukunft möglich sein, Routineanalysen von optisch-reinem Calciumfluorid durchzuführen, wobei sich im Vergleich zu naßchemischen Aufschlußverfahren eindeutige Vorteile ergeben. Neben einer deutlich einfacheren und weniger kontaminationsanfälligen Probenvorbereitung liegen die Nachweisgrenzen (im Bereich von 0.05 ng/g für Zr bis 20 ng/g für Mg) um etwa ein bis drei Größenordnungen niedriger.Die am Beispiel der Multielementbestimmung in Calciumfluorid entwickelte LA-ICP-MSIVA wurde nachfolgend anhand der Analyse von sieben zertifizierten Referenzmaterialien mit organischer und anorganischer Matrix validiert. Hierbei wurde für 28 von insgesamt 32 analysierten Elementkonzentrationen eine hervorragende Übereinstimmung mit den zertifizierten Werten erhalten. Im Mittel weichen die mittels LA-ICP-MSIVA analysierten Gehalte nur um 1.6 % von den zertifizierten Werten ab. Die erzielte Präzision von durchschnittlich 4.9 % relativer Standardabweichung für drei unabhängig analysierte Proben liegt im Bereich der durchschnittlichen zertifizierten Unsicherheit der Referenzmaterialien von 4.4 %.

Ortsaufgelöster Nachweis von Elementspuren mittels Laserablation und Resonanzionisations-Massenspektrometrie und Untersuchungen zur Laserablations-Dynamik

Im Rahmen dieser Arbeit wurde eine neue Methode für einen empfindlichen und isotopenselektiven Elementnachweis entwickelt. Unter Einsatz von Laserablation geschieht der Probenaufschluß direkt und mit einer Ortsauflösung von unter 30 m. Hierzu wurde ein hochauflösendes MALDI-TOF-Massenspektrometer, welches üblicherweise für biochemische Fragestellungen eingesetzt wird, mit einem spektroskopischen Aufbau zur resonanten Ionisation von Elementgehalten modifiziert. Die Methode ist somit insbesondere für die Untersuchung von Elementspuren in Festkörperproben mit mikroskopischer Struktur konzipiert. Methodische Entwicklungsarbeiten wurden anhand des Elements Gadolinium durchgeführt. Durch die Verwendung gepulster Farbstofflaser stehen ausreichend hohe Laserfelder zur Verfügung, um unabhängig von Hyperfeinstruktur und Isotopieverschiebung Übergänge aller Isotope im Rahmen des Resonanzionisations-Verfahrens zu sättigen. Darauf konnte eine Isotopenverhältnisanalyse mit einer Genauigkeit im Prozentbereich verwirklicht werden. Verschiedene Anregungsleitern wurden untersucht, und mit elementspezifischen Resonanzüberhöhungen bis zu zwei Größenordnungen über dem nicht-resonant gebildeten Untergrund konnte eine Nachweiseffizienz von über 10-4 (entsprechend sub-fg/g-Niveau) erzielt werden. Dazu wurden Simulationsrechnungen zum atomaren Sättigungsverhalten in starken resonanten Laserfeldern durchgeführt. Erste Anwendungen des Laserablationsverfahrens waren Proben kosmologischer Herkunft. Der physikalische Prozeß der Laserablation bei Metallen wurde unter Hochvakuum-Bedingung systematisch in Abhängigkeit der Laserfluenz untersucht. In der ablatierten Plasmaphase erwies sich der Neutralanteil als besonders geeignet für geschwindigkeitsselektive Laserionisations-Messungen. Eine bimodale Struktur wurde beobachtet, bestehend aus einer thermischen und einer schockwellen-induzierten Komponente. Der ionische Anteil der ablatierten Dampfphase konnte über variable elektrische Feldpulse untersucht werden. Laserablation unter Atmosphärenbedingung wurde an einem beschichteten Messingtarget untersucht. Dabei wurde die Entstehung von permanenten Oberflächenstrukturen beobachtet, welche sich durch Nichtgleichgewichts-Prozesse in der Dampfphase erklären lassen.

Sleep-related changes in blood pressure in hypocretin-deficient narcoleptic mice

Objectives. Blood pressure (BP) physiologically has higher and lower values during the active and rest period, respectively. Subjects failing to show the appropriate BP decrease (10-20%) on passing form diurnal activity to nocturnal rest and sleep have increased risk of target organ damage at the cardiac, vascular and cerebrovascular levels. Hypocretin (HCRT) releasing neurons, mainly located in the lateral hypothalamus, project widely to the central nervous system. Thus HCRT neurons are involved in several autonomic functions, including BP regulation. HCRT neurons also play a key role in wake-sleep cycle regulation, the lack of which becomes evident in HCRT-deficient narcoleptic patients. I investigated whether chronic lack of HCRT signaling alters BP during sleep in mouse models of narcolepsy. Methods. The main study was performed on HCRT-ataxin3 transgenic mice (TG) with selective post-natal ablation of HCRT neurons, HCRT gene knockout mice (KO) with preserved HCRT neurons, and Wild-Type control mice (WT) with identical genetic background. Experiments where replicated on TG and WT mice with hybrid genetic background (hTG and hWT, respectively). Mice were implanted with a telemetric pressure transducer (TA11PA-C10, DSI) and electrodes for discriminating wakefulness (W), rapid-eye-movement sleep (REMS) and non-REMS (NREMS). Signals were recorded for 3 days. Mean BP values were computed in each wake-sleep state and analyzed by ANOVA and t-test with significance at p<0.05. Results. The decrease in BP between either NREMS or REMS and W was significantly blunted in TG and KO with respect to WT as well as in hTG with respect to hWT. Conclusions. Independently from the genetic background, chronic HCRT deficiency leads to a decreased BP difference between W and sleep potentially adverse in narcoleptic subjects. These data suggest that HCRT play an important role in the sleep-dependent cardiovascular control.

optomotor-blind and the horizontal and vertical system cells of the drosophila optic lobes

The horizontal and vertical system neurons (HS and VS cells) are part of a conserved set of lobula plate giant neurons (LPGNs) in the optic lobes of the adult brain. Structure and physiology of these cells are well known, predominantly from studies in larger Dipteran flies. Our knowledge about the ontogeny of these cells is limited and stems predominantly from laser ablation studies in larvae of the house fly Musca domestica. These studies suggested that the HS and VS cells stem from a single precursor, which, at least in Musca, has not yet divided in the second larval instar. A regulatory mutation (In(1)omb[H31]) in the Drosophila gene optomotor-blind (omb) leads to the selective loss of the adult HS and VS cells. This mutation causes a transient reduction in omb expression in what appears to be the entire optic lobe anlage (OLA) late in embryogenesis. Here, I have reinitiated the laser approach with the goal of identifying the presumptive embryonic HS/VS precursor cell in Drosophila. The usefulness of the laser ablation approach which has not been applied, so far, to cells lying deep within the Drosophila embryo, was first tested on two well defined embryonic sensory structures, the olfactory antenno-maxillary complex (AMC) and the light-sensitive Bolwing´s organ (BO). In the case of the AMC, the efficiency of the ablation procedure was demonstrated with a behavioral assay. When both AMCs were ablated, the response to an attractive odour (n-butanol) was clearly reduced. Interestingly, the larvae were not completely unresponsive but had a delayed response kinetics, indicating the existence of a second odour system. BO will be a useful test system for the selectivity of laser ablation when used at higher spatial resolution. An omb-Gal4 enhancer trap line was used to visualize the embryonic OLA by GFP fluorescence. This fluorescence allowed to guide the laser beam to the relevant structure within the embryo. The success of the ablations was monitored in the adult brain via the enhancer trap insertion A122 which selectively visualizes the HS and VS cell bodies. Due to their tight clustering, individual cells could not be identified in the embryonic OLA by conventional fluorescence microscopy. Nonetheless, systematic ablation of subdomains of the OLA allowed to localize the presumptive HS/VS precursor to a small area within the OLA, encompassing around 10 cells. Future studies at higher resolution should be able to identify the precursor as (an) individual cell(s). Most known lethal omb alleles do not complement the HS/VS phenotype of the In(1)omb[H31] allele. This is the expected behaviour of null alleles. Two lethal omb alleles that had been isolated previously by non-complementation of the omb hypomorphic allele bifid, have been reported, however, to complement In(1)omb[H31]. This report was based on low resolution paraffin histology of adult heads. Four mutations from this mutagenesis were characterized here in more detail (l(1)omb[11], l(1)omb[12], l(1)omb[13], and l(1)omb[15]). Using A122 as marker for the adult HS and VS cells, I could show, that only l(1)omb[11] can partly complement the HS/VS cell phenotype of In(1)omb[H31]. In order to identify the molecular lesions in these mutants, the exons and exon/intron junctions were sequenced in PCR-amplified material from heterozygous flies. Only in two mutants could the molecular cause for loss of omb function be identified: in l(1)omb[13]), a missense mutation causes the exchange of a highly conserved residue within the DNA-binding T-domain; in l(1)omb[15]), a nonsense mutation causes a C-terminal truncation. In the other two mutants apparently regulatory regions or not yet identified alternative exons are affected. To see whether mutant OMB protein in the missense mutant l(1)omb[13] is affected in DNA binding, electrophoretic shift assays on wildtype and mutant T-domains were performed. They revealed that the mutant no longer is able to bind the consensus palindromic T-box element.

Method development using ICP-MS and LA-ICP-MS and their application in environmental and material science

Within this PhD thesis several methods were developed and validated which can find applicationare suitable for environmental sample and material science and should be applicable for monitoring of particular radionuclides and the analysis of the chemical composition of construction materials in the frame of ESS project. The study demonstrated that ICP-MS is a powerful analytical technique for ultrasensitive determination of 129I, 90Sr and lanthanides in both artificial and environmental samples such as water and soil. In particular ICP-MS with collision cell allows measuring extremely low isotope ratios of iodine. It was demonstrated that isotope ratios of 129I/127I as low as 10-7 can be measured with an accuracy and precision suitable for distinguishing sample origins. ICP-MS with collision cell, in particular in combination with cool plasma conditions, reduces the influence of isobaric interferences on m/z = 90 and is therefore well-suited for 90Sr analysis in water samples. However, the applied ICP-CC-QMS in this work is limited for the measurement of 90Sr due to the tailing of 88Sr+ and in particular Daly detector noise. Hyphenation of capillary electrophoresis with ICP-MS was shown to resolve atomic ions of all lanthanides and polyatomic interferences. The elimination of polyatomic and isobaric ICP-MS interferences was accomplished without compromising the sensitivity by the use of a high resolution mode as available on ICP-SFMS. Combination of laser ablation with ICP-MS allowed direct micro and local uranium isotope ratio measurements at the ultratrace concentrations on the surface of biological samples. In particular, the application of a cooled laser ablation chamber improves the precision and accuracy of uranium isotopic ratios measurements in comparison to the non-cooled laser ablation chamber by up to one order of magnitude. In order to reduce the quantification problem, a mono gas on-line solution-based calibration was built based on the insertion of a microflow nebulizer DS-5 directly into the laser ablation chamber. A micro local method to determine the lateral element distribution on NiCrAlY-based alloy and coating after oxidation in air was tested and validated. Calibration procedures involving external calibration, quantification by relative sensitivity coefficients (RSCs) and solution-based calibration were investigated. The analytical method was validated by comparison of the LA-ICP-MS results with data acquired by EDX.

Immunohistochemical and Molecular Prognostic/Predictive Markers in Neoplastic Diseases

Traditional morphological examinations are not anymore sufficient for a complete evaluation of tumoral tissue and the use of neoplastic markers is of utmost importance. Neoplastic markers can be classified in: diagnostic, prognostic and predictive markers. Three markers were analyzed. 1) Insulin-like growth factor binding protein 2 (IGFBP2) was immunohistochemically examined in prostatic tissues: 40 radical prostatectomies from hormonally untreated patients with their preoperative biopsies, 10 radical prostatectomies from patients under complete androgen ablation before surgery and 10 simple prostatectomies from patients with bladder outlet obstruction. Results were compared with α-methylacyl-CoA racemase (AMACR). IGFBP2 was expressed in the cytoplasm of untreated adenocarcinomas and, to a lesser extent, in HG-PIN; the expression was markedly lower in patients after complete androgen ablation. AMACR was similarly expressed in both adenocarcinoma and HG-PIN, the level being similar in both lesions; the expression was slightly lower in patients after complete androgen ablation. IGFBP2 may be used a diagnostic marker of prostatic adenocarcinomas. 2) Heparan surface proteoglycan immunohistochemical expression was examined in 150 oral squamous cell carcinomas. Follow up information was available in 93 patients (range: 6-34 months, mean: 19±7). After surgery, chemotherapy was performed in 8 patients and radiotherapy in 61 patients. Multivariate and univariate overall survival analyses showed that high expression of syndecan-1 (SYN-1) was associated with a poor prognosis. In patients treated with radiotherapy, such association was higher. SYN-1 is a prognostic marker in oral squamous cell carcinomas; it may also represent a predictive factor for responsiveness to radiotherapy. 3) EGFR was studied in 33 pulmonary adenocarcinomas with traditional DNA sequencing methods and with two mutation-specific antibodies. Overall, the two antibodies had 61.1% sensitivity and 100% specificity in detecting EGFR mutations. EGFR mutation-specific antibodies may represent a predictive marker to identify patients candidate to tyrosine kinase inhibitors therapy.

Cambiamenti dello scenario epidemiologico e clinico dell'epatocarcinoma in Italia nell'ultimo ventennio

Background & Aims: This study investigates whether the aetiologic changes in liver disease and the improved management of hepatocellular carcinoma (HCC) have modified the clinical scenario of this tumour over the last 20 years in Italy. Methods: Retrospective study based on the analysis of the ITA.LI.CA (Italian Liver Cancer) database including 3027 HCC patients managed in 11 centres. Patients were divided into 3 groups according to the period of HCC diagnosis: 1987–1996 (year of the ‘‘Milano criteria’’ publication), 1997–2001 (year of release of the EASL guidelines for HCC), and 2002–2008. Results: The significant changes were: (1) progressive patient ageing; (2) increasing prevalence of HCV infection until 2001, with a subsequent decrease, when the alcoholic aetiology increased; (3) liver function improvement, until 2001; (4) increasing ‘‘incidental’’ at the expense of ‘‘symptomatic’’ diagnoses, until 2001; (5) unchanged prevalence of tumours diagnosed during surveillance (around 50%), with an increasing use of the 6- month schedule; (6) favourable HCC ‘‘stage migration’’, until 2001; (7) increasing use of percutaneous ablation; (8) improving survival, until 2001. Conclusions: Over the last 20 years, several aetiologic and clinical features regarding HCC have changed. The survival improvement observed until 2001 was due to an increasing number of tumours diagnosed in early stages and in a background of compensated cirrhosis, and a growing and better use of locoregional treatments. However, the prevalence of early cancers and survival did not increase further in the last years, a result inciting national policies aimed at implementing surveillance programmes for at risk patients.

Ansatz zur Generierung einer konditionalen, reversiblen Wt1 k.o.-Maus

Ansatz zur Generierung einer konditionalen, reversiblen Wt1 k.o.-Maus Der Wilms-Tumor (WT, Nephroblastom) ist ein embryonaler Nierentumor, der durch die maligne Transformation von undifferenziertem Nierengewebe, sog. nephrogenen Resten, entsteht. WT treten mit einer Inzidenz von 1 in 10.000 Lebendgeburten auf. Das Hauptmanifestationsalter, der normalerweise einseitig und sporadisch auftretenden Tumore, liegt zwischen dem 3. und 4. Lebensjahr. Etwa 10 % der Patienten entwickeln jedoch bilaterale Tumore. In diesen Fällen ist eine Assoziation mit komplexen genetischen Krankheitsbildern (u. a. WAGR-, Denys-Drash-, Frasier- und Beckwith-Wiedemann-Syndrom) festzustellen. In 15 % der sporadischen WT sind Mutationen im WT1 (Wilms-Tumor 1)-Gen beschrieben. WT1 besteht aus zehn Exons und weist typische Merkmale von Transkriptionsfaktoren (z. B. vier Zinkfinger) auf. Zwei alternative Spleißereignisse betreffen Exon 5 (+/−Exon 5) und Exon 9 (Transkripte mit bzw. ohne die codierenden Sequenzen für die AS Lysin-Threonin-Serin; +/−KTS). Die Lage der drei alternativ vorhandenen AS zwischen den Zinkfingern 3 und 4 bestimmt die verschiedenen Funktionen der WT1-Proteine (4 Isoformen) als Transkriptionsfaktor (−KTS) bzw. als RNA-bindendes Protein (+KTS). Das zunächst im Zusammenhang mit WT als Tumorsuppressorgen identifizierte WT1 ist ein Entwicklungsgen mit einem sehr komplexen Expressionsmuster in der Embryonalentwicklung. Dabei ist v. a. die Bedeutung in der Urogenitalentwicklung entscheidend. Konstitutive, homozygote Wt1−/− k.o.-Mäuse sind embryonal (~ E12,5 dpc) letal und bilden u. a. keine Gonaden und keine Nieren. Aus diesem Grund existiert bisher kein Wilms-Tumormodell. Die Herstellung eines konditionalen murinen Tiermodells auf Basis des Tet on/off-Systems zur Untersuchung der Nierenentwicklung bzw. zur Analyse der Wilms-Tumorpathogenese war Ziel dieser Arbeit. Hierfür wurden drei Mauslinien generiert: Zwei transgene sog. Responder-Linien, die eine chimäre spleißbare Wt1-cDNA der Variante musWt1+Exon 5;+/−KTS unter der Kontrolle eines Tet-responsiven Promotors im Genom tragen. Dieses tTA/Dox-abhängig regulierbare Wt1-Transgen (tgWt1) sollte (exogen regulierbar) die Expression des endogenen Wt1-Lokus ausreichend nachahmen, um die kritischen Phasen der Embryogenese zu überwinden und lebensfähige Tiere zu erhalten. Parallel dazu wurde die Wt1-Effektor-Mauslinie (WE2) generiert. Diese trägt einen tetrazyklinabhängigen Transaktivator (tTA) zur Steuerung Tet-regulierbarer Transgene unter der Kontrolle des endogenen Wt1-Promotors. Die durch homologe Rekombination in ES-Zellen erreichte Integration des tTA direkt am Translationsstartpunkt des Wt1-Lokus hat in den Tieren einen heterozygoten Wt1 knock out/tTA knock in zur Folge. Die bisher vorgenommenen Verpaarungen doppelt transgener Wt1-tTA+/−/Resp-Mäuse ergaben keinen Rescue des letalen Wt1 k.o. und es konnten bislang keine Wilms-Tumore induziert werden. Alle im Verlauf der Arbeit generierten Mauslinien wurden umfassend charakterisiert. So konnte für die Tiere der Responder-Linien Wt1-Resp1 (mit zusätzlichen Isolator-Sequenzen zum Schutz des Transgens vor Positionseffekten) und Wt1-Resp2 (ohne Isolatoren) konnte die Tet-induzierbare Expression und die Spleißbarkeit des tgWt1 in MEF-Assays und mittels Effektor-Mäusen auf RNA-Ebene nachgewiesen werden. Die genomische Charakterisierung der WE2-Linie ergab eine ungeklärte etwa 120 kb große Inversion am Wt1-Lokus, die alle 5'-regulatorischen Sequenzen mitsamt des tTA vom Rest von Wt1 trennt. Tiere dieser Linie weisen aber dennoch einen funktionalen Wt1 k.o. auf: Unter den Nachkommen aus Intercross-Verpaarungen von Wt1-tTA+/−-Mäusen lassen sich auf Grund der Letalität keine Wt1−/−-Genotypen nachweisen. Die Charakterisierung der Effektor-Linie auf RNA-Ebene und mittels Reporter-Mäusen liefert ein Wt1-analoges tTA-Expressionsmuster: So findet man eine deutliche tTA-Expression u. a. in Niere (Glomeruli), Uterus, Ovar und Testis. Die hier vorgestellten Experimente ergeben darüber hinaus eindeutige Hinweise einer Beteiligung von Wt1 in der Entstehung der glatten Muskulatur bzw. in der Vaskulogenese.