Geologi-geoscience i København - en verden af muligheder

Geologi-geoscience-studiet på Københavns Universitet er for dig, der gerne vil beskæftige dig tværfagligt med naturvidenskab i et bredt perspektiv og samtidig få en samfundsanvendelig viden inden for eksempelvis olie, råstoffer, grundvand, klima og miljø - en viden, der lige nu efterspørges af arbejdsmarkedet i Danmark og i udlandet

Untersuchungen am Trachealaspirat beatmeter Früh- und Reifgeborener zur Infektionsdiagnostik und Prädiktion der Bronchopulmonalen Dysplasie - eine Pilotstudie

Eine Frühgeburt birgt aufgrund der Unreife der Organsysteme des Neugeborenen erhöhte Krankheitsrisiken. Dazu zählen unter anderem Infektionserkrankungen und die Bronchopulmonale Dysplasie (BPD). Early- oder Late-Onset Infektionen durch diverse Erreger sind bei Frühgeborenen eine der Hauptursachen für die Mortalität in der Neonatalperiode. Bei der BPD führen inflammatorische Prozesse in der unreifen Lunge zu einer chronischen Lungenschädigung mit persistierendem Sauerstoffbedarf im Verlauf. Hierfür fehlen valide Frühvorhersagemodelle. Auch was Infektionserkrankungen betrifft, ergeben sich bei Früh- und Neugeborenen wegen der unspezifischen Symptomatik diagnostische Schwierigkeiten. Im Hinblick auf die Prädiktion der BPD und die Diagnostik von systemischen Infektionen erfolgten in der vorliegenden Arbeit Untersuchungen am Trachealaspirat von 33 intubierten Früh- und Reifgeborenen. Das Trachealaspirat wurde beim routinemäßigen Absaugen der Patienten gewonnen. Die Konzentrationen der Zytokine IL-6 und IFN-γ im Trachealaspirat wurden mittels Immunassay bestimmt. Zudem wurden die Trachealaspiratproben mit zwei verschiedenen mikrobiologischen Untersuchungsverfahren auf das Vorhandensein von Bakterien untersucht: Der konventionelle Untersuchungsansatz umfasste Färbung und Mikroskopie sowie kulturelle Anzucht, der molekulare Ansatz bestand aus einer PCR der im Trachealaspirat vorhandenen 16S-rDNA sowie chromatographischer Auftrennung und Sequenzierung der Amplifikate. Des Weiteren kam eine Elektronische Nase zum Einsatz, ein tragbares Gerät, das volatile organische Substanzen (VOCs) detektiert. So wurde ein Smellprint, also ein Profil der emittierten Substanzen, für jede Trachealaspiratprobe – ähnlich einem individuellen Fingerabdruck – erstellt. Die Untersuchung zeigte keine signifikanten Unterschiede der Konzentrationen der Zytokine IL-6 und IFN-γ im Trachealaspirat von Frühgeborenen mit einem Gestationsalter < 32 SSW, die später eine BPD entwickelten und denen, die keine BPD entwickelten. Die Zytokinkonzentrationen im Trachealsekret korrelierten ebenfalls nicht mit dem Vorliegen einer systemischen Infektion oder dem Bakteriennachweis im Trachealaspirat. Der Vergleich des konventionellen und genomischen Erregernachweises im Trachealaspirat zeigte eine erhebliche Diskrepanz. Bei Patienten, die später eine BPD entwickelten, zeigten sich signifikant häufiger Bakterien im Trachealaspirat. Die erstmalig bei Neugeborenen durchgeführte Analyse der durch die Elektronische Nase erstellten Smellprints erbrachte erfolgversprechende Ergebnisse: Die Smellprints der Trachealaspirate von Frühgeborenen, die später eine BPD entwickelten und Frühgeborenen, die keine BPD entwickelten, unterschieden sich in der Diskriminanzanalyse signifikant. Ebenso unterschieden sich die Smellprints von Patienten mit einer laborchemisch bestätigten Infektion signifikant von Patienten ohne Infektionsparameter, unabhängig davon, ob Letztere einen positiven Keimnachweis im Trachealaspirat hatten oder nicht. Der Einsatz der Elektronischen Nase in der Neugeborenenmedizin ist also vielversprechend hinsichtlich der Prädiktion der BPD sowie der Diagnostik von systemischen Infektionen. Es sind jedoch weitere Studien zur Validierung dieser Methode notwendig

Interobserver agreement of Thyroid Imaging Reporting and Data System (TIRADS) and strain elastography for the assessment of thyroid nodules

Background: Thyroid Imaging Reporting and Data System (TIRADS) was developed to improve patient management and cost-effectiveness by avoiding unnecessary fine needle aspiration biopsy (FNAB) in patients with thyroid nodules. However, its clinical use is still very limited. Strain elastography (SE) enables the determination of tissue elasticity and has shown promising results for the differentiation of thyroid nodules. Methods: The aim of the present study was to evaluate the interobserver agreement (IA) of TIRADS developed by Horvath et al. and SE. Three blinded observers independently scored stored images of TIRADS and SE in 114 thyroid nodules (114 patients). Cytology and/or histology was available for all benign (n = 99) and histology for all malignant nodules (n = 15). Results: The IA between the 3 observers was only fair for TIRADS categories 2–5 (Coheńs kappa = 0.27,p = 0.000001) and TIRADS categories 2/3 versus 4/5 (ck = 0.25,p = 0.0020). The IA was substantial for SE scores 1–4 (ck = 0.66,p<0.000001) and very good for SE scores 1/2 versus 3/4 (ck = 0.81,p<0.000001). 92–100% of patients with TIRADS-2 had benign lesions, while 28–42% with TIRADS-5 had malignant cytology/histology. The negative-predictive-value (NPV) was 92–100% for TIRADS using TIRADS-categories 4&5 and 96–98% for SE using score ES-3&4 for the diagnosis of malignancy, respectively. However, only 11–42% of nodules were in TIRADS-categories 2&3, as compared to 58–60% with ES-1&2. Conclusions: IA of TIRADS developed by Horvath et al. is only fair. TIRADS and SE have high NPV for excluding malignancy in the diagnostic work-up of thyroid nodules

Mechanical Adaptive Silicone Composites for UV-triggered Facilitated Cochlear-Implant Removal

The removal of the cochlear implant (CI), which in some cases is without alternative, is still an act of simple pulling, not only causing harm for the patient by damaging tissue but also making reimplantation more difficult. For that reason, it is necessary to develop mechanisms to make an explantation easier. To overcome this problem adaption of the mechanical properties by light-degradable periodic mesoporous organosilica (PMO) can be one solution. By introducing PMO nanoparticles into the CI's silicone matrix, the particles act as a stiffening agent, which can be degraded by irradiation with UV light. Using this mechanism, the silicone becomes softer, thus making explantation easier and safer for patients. Here first results, concerning the creation of a silicone composite material with light-sensitive adaptive mechanical properties are reported

Predator avoidance in extremophile fish

Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis

Core-Shell-Nanoparticles with Superparamagnetic Properties for Novel Applications as Biomaterials

Due to the increasing average age of the population, the number of implants is also increasing and with it the number of explantations. Therefore, facilitated implant removal is of great interest. A nanocomposite consisting of superparamagnetic core-shell nanoparticles (CSNPs) and a synthetic polymer is supposed to be used as implant coating, aiming for a stimulus-inducible modification of the composite's rheological properties by hyperthermia. Here, the first steps following this concept, the synthesis and modification of the CSNP are reported. In this work magnetite nanoparticles build the core and are surrounded by a periodic mesoporous organisilica (PMO) shell. For this reason, the CSNP are referred to as magnetic PMO (mPMO) particles in the following

How lipid flippases can modulate membrane structure

AbstractPhospholipid flippases, are proteins able to translocate phospholipids from one side of a membrane to the other even against a gradient of concentration and thereby able to establish, or annihilate, a transmembrane asymmetrical lipid distribution. This lipid shuttling forms new membrane structures, in particular vesicles, which are associated with diverse physiological functions in eukaryotic cells such as lipid and protein traffic via vesicles between organelles or towards the plasma membrane, and the stimulation of fluid phase endocytosis. The transfer of lipids is also responsible for the triggering of membrane associated events such as blood coagulation, the recognition and elimination of apoptotic or aged cells, and the regulation of phosphatidylserine dependent enzymes. Exposure of new lipid-head groups on a membrane leaflet by rapid flip-flop can serve as a specific signal and, upon recognition, can be the cause of physiological modifications. Membrane bending is one of the mechanisms by which such activities can be triggered. We show that the lateral membrane tension is an important physical factor for the regulation of the size of the membrane invaginations. Finally, we suggest in this review that this diversity of functions benefits from the diversity of the lipids existing in a cell and the ability of proteins to recognize specific messenger molecules

Acoustic radiation force impulse imaging for differentiation of thyroid nodules

Background: Acoustic Radiation Force Impulse (ARFI)-imaging is an ultrasound-based elastography method enabling quantitative measurement of tissue stiffness. The aim of the present study was to evaluate sensitivity and specificity of ARFI-imaging for differentiation of thyroid nodules and to compare it to the well evaluated qualitative real-time elastography (RTE). Methods: ARFI-imaging involves the mechanical excitation of tissue using acoustic pulses to generate localized displacements resulting in shear-wave propagation which is tracked using correlation-based methods and recorded in m/s. Inclusion criteria were: nodules $5 mm, and cytological/histological assessment. All patients received conventional ultrasound, real-time elastography (RTE) and ARFI-imaging. Results: One-hundred-fifty-eight nodules in 138 patients were available for analysis. One-hundred-thirty-seven nodules were benign on cytology/histology, and twenty-one nodules were malignant. The median velocity of ARFI-imaging in the healthy thyroid tissue, as well as in benign and malignant thyroid nodules was 1.76 m/s, 1.90 m/s, and 2.69 m/s, respectively. While no significant difference in median velocity was found between healthy thyroid tissue and benign thyroid nodules, a significant difference was found between malignant thyroid nodules on the one hand and healthy thyroid tissue (p = 0.0019) or benign thyroid nodules (p = 0.0039) on the other hand. No significant difference of diagnostic accuracy for the diagnosis of malignant thyroid nodules was found between RTE and ARFI-imaging (0.74 vs. 0.69, p = 0.54). The combination of RTE with ARFI did not improve diagnostic accuracy. Conclusions: ARFI can be used as an additional tool in the diagnostic work up of thyroid nodules with high negative predictive value and comparable results to RTE

How do signers mark conditionals in German Sign Language? Insights from a Sentence Reproduction Task on the use of nonmanual and manual markers

This paper presents the results of a Sentence Reproduction Task (SRT) investigating conditional sentences in German Sign Language (DGS). We found that participants mark conditional sentences in DGS by systematically using different non-manual markers on the antecedent and the consequent. In addition, these non-manual markers were frequently used in combination with one or two manual signs. However, the manual markers were omitted in the test sentences, i.e., the input stimuli the participants were asked to reproduce. The results of our experimental study are, on the one hand, consistent with descriptions of manual and non-manual strategies used to mark conditional sentences in different unrelated sign languages. On the other hand, our findings provide new insights on the multi-layered marking of conditional sentences in DGS

Isolation from forest reduces pollination, seed predation and insect scavenging in Swiss farmland

Habitat loss and fragmentation lead to changes in species richness and composition which may affect ecosystem services. Yet, few studies distinguish between the effects of habitat loss and isolation, or how multiple ecosystem services may be affected simultaneously. We investigated the effects of variation in cover of woody and open semi-natural habitats and isolation from forest on the relative functioning of pollination, seed predation and insect scavenging in agricultural landscapes. We established 30 sites in grassland locations in the Swiss plateau around Berne. The sites varied independently in their isolation from forest edges, in the percentage of woody habitats and in the percentage of open semi-natural habitats in the surrounding landscape (500m radius). We experimentally exposed primroses, sunflower seeds and cricket corpses during spring 2008. None of the three studied services was affected by variation in woody or open semi-natural habitat cover. However, the proportion of flowers setting seed was significantly reduced by isolation from forest. Further, seed predation and insect scavenging were significantly lower at isolated sites than at sites connected to woody habitat. This pattern was particularly pronounced for seeds and insect corpses that were enclosed by wire netting and thus inaccessible to vertebrates. Thus, all three studied services responded quite similarly to the landscape context. The observed small-scale determination of seed set, seed predation and insect scavenging contrasts with larger-scale determination of pollination and insect pest control found in other studie