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The strong nuclear force is described by Quantum Chromodynamics (QCD), the parallel field theory to Quantum Electrodynamics (QED) that describes the electromagnetic force. It is propagated by gluons analogously to photons in the electromagnetic force, but unlike photons, which do not carry electric charge, gluons carry color, and they can self-interact. However, as individual quarks have never been observed in nature, it is postulated that the color charge itself is confined, and hence all baryons and mesons must be colorless objects. To study nuclear matter under extreme conditions, it is necessary to create hot and dense nuclear matter in the laboratory. In such conditions the confinement between quarks and gluons is cancelled (deconfinement). This state is characterized with a qusi-free behavior of quarks and gluons. The strange (s) and anti-strange (anti-s) quarks are not contained in the colliding nuclei, but are newly produced and show up in the strange hadrons in the final state. It was suggested that strange particle production is enhanced in the QGP with respect to that in a hadron gas. This enhancement is relative to a collision where a transition to a QGP phase does not take place, such as p+p collisions where the system size is very small. Therefore the energy- and system size dependence is studied to receive a picture about the initial state. In this thesis experimental results on the energy- and system size dependence of Xi hyperon production at the CERN SPS is shown. All measurements were performed with the NA49 detector at the CERN SPS. NA49 took central lead-lead collisions from 20 - 158 AGeV, minimus bias lead-lead collisions at 40 and 158 AGeV, and semi-central silicon-silicon colisions at 158 AGeV. The NA49 experiment features a large acceptance in the forward hemisphere allowing for measurements of Xi rapidity spectra. At the SPS accelerator at CERN Pb+Pb collisions are performed with beam energies to 158 AGeV. The analyzed data sets were taken in the period from 1999 to 2002. The NA49 experiment is a large acceptance hadron spectrometer, which measures charged hadrons in a wide acceptance. The main components are the four TPCs (Time Projection Chamber). The centrality of nucleon-nucleon collisions was done by measuring the not in the collision participating (spectator-) nucleons in the VETO-calorimeter. The study of strangeness is motivated by its role as a signature for the Quark Gluon Plasma. Any enhancement in the yield must be with respect to a ’normal’ yield, where a QGP is not formed. This is usually taken to mean suitably scaled p+p collisions, where the volume of the system created is too small for a QGP to occur. The results at SPS and RHIC energies show an enhancement, with the doubly strange Xi? being enhanced more than the Lambda, in accordance with the original prediction. However, the enhancement at SPS energies is higher than at RHIC energies.
Koalas are popular zoo animals, but difficult in husbandry. In addition to their specialised diet of eucalyptus leaves, they are prone to “stress” and disease. Particularly in European zoos, themonitoring of theirwell-being has high priority and they are protected from possible stressors. However, stress signs in koalas are vague and monitoring techniques like weighing might result in discomfort itself. Additionally, husbandry routines are planned according to keeper’s schedule, not to the endogenous rhythms of the koalas. Therefore it is necessary to investigate activity pattern in captive koalas and the signals influencing them. These signals have to be assessed on the strength and quality of their impact. A total of 17 koalas have been observed in three zoological gardens in Australia and Europe. Koalas kept in outdoor enclosures with little human contact (Koala Walkabout, Taronga Zoo, Sydney) showed a uniform activity pattern, which was clearly entrained by light. Activity levels were higher during the night, and there was a pronounced resting period in the morning which corresponds with low body temperature measured by Degabriele and Dawson (1979). Activity peaks were related to twilight and changed during the year related to day lengths. However, there was a clear influence from the introduction of fresh browse which resulted in a distinct feeding peak in the afternoon. With short day lengths, this stimulus competed with dusk. Activity patterns from koalas in indoor enclosures (Zoo Duisburg, Vienna Zoo) varied between individuals and in some cases lacked a detectable rhythm. Though activity peaks were related to light, entrainment to sunlight was weak. In winter, koalas reacted primarily to the artificial light, but some also showed activity peaks related to sunlight. Activity patterns in these koalas were less structured and differed severely from patterns expected according to literature. Activity was often related to the keeper’s presence and food introduction. Frequency of feeding bouts was considerably higher at Vienna Zoo compared to the other zoos and the bouts were shorter in duration. Time budgets of the koalas were within the range given in free-range studies. Feeding showed seasonal changes and was increased in lactating females. Koalas at Vinna Zoo had a high level of locomotor activity compared to the size of the enclosure. Koalas at Koala Walkabout were not used to handling, so they resisted the keeper. The koalas at the two European zoos were handled regularly and settled down quickly. However, handling took place in the morning; in most koalas, there was no activity prior to it. In Vienna, resting periods were interrupted daily due to weighing. Food introduction at KoalaWalkabout took place in the afternoon. It was preceded by locomotor activity and triggered a long feeding bout in the koalas. It is not clear, whether food had true Zeitgeber properties or masked the endogenous rhythm. In the two European zoos, food was introduced in the morning. The peaks related to this were smaller than those at Koala Walkabout. Activity was rarely observed prior to food introduction. The koalas at Koala Encounter, Taronga Zoo (Sydney),were regularly confronted with visitors, though no contact was allowed. Direct observation by the keepers did rarely show any stress signs. Activity patterns at night were strikingly similar to Koala Walkabout, but differed dramatically during the day. Food was introduced three times a day, which usually resulted in activity that interrupted a resting period. Generally, the koalas at Koala Encounter were more active than those at KoalaWalkabout. They also displayed a high level of locomotor activity, especially on the ground, which is an accepted sign of discomfort in koalas (Wood 1978; Zoological Society of San Diego 2001; Yusuf& Rosenthal unpublished data). In summary, this chronoethological study of the captive koalas showed that there are several problems with koala husbandry. Artificial light regimes for koalas are not sufficient for entrainment and result in unstructured activity pattern. This is especially the case in winter, when the day in Europe is artificially extended. Due to the mainly nocturnal behaviour of koalas, such an extension might not be necessary and therefore should be avoided. Handling in Europe took place during the physiological resting time of the koalas. Interruptions of resting times are considered as stressors (Wood 1978) and should be avoided. Handling in the afternoon would be more suitable for the koalas and triggered activity in the two koalas at Vienna Zoo. It is also arguable if daily weighing is necessary to monitor health in captive koalas or if the frequent interruption of resting countervail the advantages of constant monitoring. Frequent contact with visitors, evenwithout the so-called cuddling, has a considerable impact on activity patterns and time budget of koalas, even if no immediate stress signs are displayed. Such contact should therefore be reduced to a minimum and chronoethological observations of the koalas should be used. A study on koalas with direct visitor contact is also advisable to revise the current legislation on “koala cuddling”. Koalas frequently rested in living trees if they had access to it. Since no food-poisoning has been reported from koalas using living non-food trees, the provision of living trees with an appropriate canopy should be included in the husbandry guidelines. Increased locomotor activity has been shown to be related to conditions of discomfort or stress and possibly to oestrus. This is in accordance with literature (Wood 1978; Zoological Society of San Diego 2001). Further observation, combined with hormone analysis, are advisable to establish this parameter for evaluation of well-being. Chronoethology has proven to be useful for the evaluation of husbandry conditions and group dynamics. Different to other, traditional ethologicalmethods, it indicated problems and enabled me to advise more appropriate times for handling and food introduction. It is desirable that zoos already using 24-hour video observation include chronoethological aspects into their analysis.
Synaptopodin is the founding member of a family of actin-associated proline-rich proteins. It is present in a subset of telencephalic dendritic spines, where it is tightly associated with the dendritic spine apparatus, a putative calcium store. Synaptopodin-deficient mice lack the spine apparatus and show deficits in long-term potentiation and spatial memory. Thus, synaptopodin appears to play a role in synaptic plasticity. In the present thesis, three major questions were addressed: (1) What is the distribution of synaptopodin and the spine apparatus in identified hippocampal neurons? (2) Is the distribution of synaptopodin affected by denervation? (3) Is synaptopodin involved in the regulation of denervation-induced spine loss? The major findings of this thesis are: (1) Immunohistochemistry in the hippocampus of wildtype and EGFP-transgenic mice revealed significant layer-specific differences in the prevalence of synaptopodin at the level of individual neurons. (2) Light and electron microscopic analysis also revealed the presence of synaptopodin in axon initial segments of cortical and hippocampal principal neurons. There, it was found to be an essential component of the cisternal organelle, a putative axonal homologue of the dendritic spine apparatus. (3) Immunohistochemistry in the rat fascia dentata before and following entorhinal deafferentation revealed changes in synaptopodin expression in denervated and non-denervated layers of the hippocampus, suggesting that the distribution of synaptopodin in hippocampal neurons is regulated by presynaptic signals. (4) The dynamics of denervation-induced spine plasticity were studied in vitro using confocal live imaging of organotypic entorhino-hippocampal slice cultures. Whereas spines were remarkably stable under control conditions, spine loss and spine formation were seen following denervation. No significant differences were observed between cultures from wildtype and synaptopodin-deficient mice, suggesting that synaptopodin is not involved in lesion-induced spine plasticity. (5) Finally, a set of transgenic mice expressing fluorescently tagged synaptopodin were generated to facilitate future experiments on the dynamics and function of synaptopodin. In summary, this thesis presents novel findings on (1) the subcellular distribution of synaptopodin in spines and the axon initial segment, (2) the molecular composition of the cisternal organelle, and (3) the dynamics of spines and the spine apparatus organelle following deafferentation in vivo and in vitro.
An application of EPR spectroscopy that is becoming increasingly important is the measurement of distances between electron spins. Several EPR methods have been developed for this purpose, all based on measuring the dipolar coupling between two spins. Due to the specific nature of the sample, we applied dipolar relaxation enhancement measurements to study the geometry of a protein-protein complex. The paramagnetic centers in question had EPR spectra that were too broad and had such short relaxation time that they could not be studied using the more straightforward PELDOR technique. EPR spectral resolution can be increased appreciably by measuring at a frequency higher than conventional X-band (9 GHz) frequency. The spectra of many paramagnetic species can only be resolved at frequencies higher than 90 GHz. For accurate measurement of the orientation of the vector between two dipolar coupled spins with respect to the g-tensors of the spins, high spectral resolution is required. We therefore performed our EPR measurements at G-band (180 GHz) frequency. Dipolar relaxation measurements were applied to study the complex that is formed by the two electron-transfer proteins cytochrome c and cytochrome c oxidase (CcO) from the soil bacterium Paracoccus denitrificans. We were able to detect dipolar relaxation enhancement due to complex formation of soluble subunit II of P.d. CcO (CcOII) with two substrate cytochromes, which was practically absent in a mixture of CcOII with the negative control protein cytochrome c1. This complex formation was characterized by a pronounced temperature dependence that could be simulated using a home-written computer program. The G-band EPR measurements could not be simulated with a single complex geometry. This provided evidence for the hypothesis that electron-transfer protein complexes are short-lived and highly dynamic; they do not seem to form one specific electron-transfer conformation, but rather move around on each other’s binding surfaces and transfer an electron as soon as the distance between donor and acceptor is short enough. As a test of our simulation program, we also applied dipolar relaxation measurements to specially synthesized organic molecules that contained a nitroxide radical and a metal center. The transverse relaxation of Cu2+-OEP-TPA was compared to the relaxation of Ni2+-OEP-TPA at temperatures between 20 and 120 K. In this temperature range, the nitroxide relaxation was enhanced due to the presence of Cu2+, but not by Ni2+. Similarly, relaxation enhancement was found in the nitroxide-Mn2+ pair in Mn2+-terpyridine-TPA with respect to the terpyridine-TPA ligand. Due to the fast T2 relaxation of the nitroxide radical at high temperatures, the measurements were all performed in the low-temperature regime where the T1 relaxation rate of the metal ion was smaller than the dipolar coupling frequency. In this region, no structural information about the molecule can be deduced, since the dipolar relaxation enhancement is only determined by the T1 of the metal ion. The dipolar relaxation measurements we performed at high field indicated a difference in relaxation times between X-band and G-band frequencies. Extensive T1 - measurements of different paramagnetic centers (CuA, Cu2+) confirmed a strong dependence of T1 on magnetic field in the temperature range where the direct process is the dominating T1 relaxation process. This dependence is very strong (factor of 103 with respect to X-band), but does not follow the B04 dependence predicted in literature. The T1 relaxation of low-spin iron in cytochrome c at high magnetic field, estimated from dipolar relaxation data, is also in agreement with a larger contribution by the direct process (factor of 104). Dipolar relaxation enhancement was found to be a technique that is useful for measuring distances between paramagnetic centers, but only for systems where several important conditions are met, such as: the system exists in one certain static geometry, and the relaxation rate of the fast-relaxing spin is faster than the dipolar coupling frequency within the accessible temperature range. Additionally, it is a great advantage for the analysis of dipolar relaxation data if the procedure of dividing the relaxation trace of the dipolar-coupled slow-relaxing spin by the relaxation trace of the slow-relaxing spin in absence of dipolar coupling can be applied. Another useful application of dipolar relaxation enhancement measurements is the measurement of T1 relaxation of extremely fast-relaxing spins, or spins that are otherwise difficult to detect.
Die vorliegende Arbeit behandelt die Entwicklung und Überprüfung von Modellen zur Berechnung von Schwingungspektren von Peptiden und Proteinen. Solche Modelle verbinden die Konformationsstruktur eines Moleküls mit seinen Schwingungseigenschaften und sind demzufolge wichtig für die Interpretation der Schwingungspektren. Die im Rahmen dieser Arbeit durchgeführte theoretische Erforschung dieses Gebietes beschränkt sich auf die Betrachtung der Amide-I-Moden, welche aufgrund ihrer physikalischen Eigenschaften sich zur Untersuchung der Peptidkonformationen eignen. Die Arbeit kann prinzipiell in zwei Teile separiert werden. In dem ersten Teil werden Fragen betrachtet, die mit der Entwicklung des Schwingungshamiltonian verbunden sind. Im zweiten Teil wurden die erhaltenen Hamiltonian für die Berechnung der Schwingungspektren verwendet. Bei der Berechnung der Schwingungspektren wurden verschiedene spektroskopische Näherungen verwendet und erforscht. Die Entwicklung des Schwingungshamiltonian beinhaltet zwei Aufgaben. Die ab initio Parametrisierung des Schwingungshamiltonian von Dipeptiden, sowie die Analyse der Entwicklungsmethoden für Schwingungshamiltonian von Polypeptiden. Die Entwicklungsmethoden stützen sich auf ab initio berecheten Schwingungseigenschaften von Dipeptiden und/oder elektrostatische Modelle. Die ab initio Parametrisierung basiert auf einer Geometrieoptimierung und anschließender Berechnung von Normalmoden. Hierbei wurde die Abhängigkeit der Ergebnisse vom theoretischen Niveau und dem verwendeten Basissatz untersucht. Die Transformation der errechneten Normalmoden lieferte die Schwingungseigenschaften der lokale Amide-I-Mode. Die Lokalisierung der Normalmode folgt diversen Kriterien. Sie ist von der Wahl der Lokalmoden und somit implizit auch von der Art der Geometrieoptimierung abhängig. Mit dieser Arbeit konnte die Abhängigkeit der Ergebnisse von der Parameterwahl weitgehend aufgeklärt und eine für das Amide-I-System geeignet Parametrisierung gefunden werden. Im nächsten Arbeitsschritt wurde die Abhängigkeit der Amide-I-Schwingungseigenschaften von den Peptidseitenketten und terminalen Gruppen untersucht. Desweiteren wurden Methoden zur Formulierung der Hamiltonian für Polypeptide konzeptionell entwickelt. Diese Untersuchung ist außerordentlich wichtig, da direkte quantenmechanische Berechnungen von Polypeptiden zu zeitaufwendig sind. Solche Methoden beruhen auf dem sogenannten “Building-Block”-Ansatz und verschiedenen elektrostatischen Modellen. In dieser Arbeit wurden sowohl die einzelnen Methoden als auch ihre Kombination für die Entwicklung des Hamiltonians verwendet. Zur Abschätzung der Genauigkeit der verwendeten Methoden wurden Vergleichsrechnungen durchgeführt. Im zweiten Teil dieser Arbeit wurden die erhaltenen Schwingungshamiltonian zur Berechnung von Schwingungsspektren diverser gelöster Peptide angewandt. In diesem Zusammenhang konnte die Genauigkeit unterschiedlicher spektroskopischer Approximationen überprüft werden. Auf Grundlage der erhaltenen Ergebnisse können wir sagen, dass eine angemessene Beschreibung der konformationellen Verteilung und eine korrekte Berechnung des dynamischen Absorptionsspektrum gewährleistet ist. Was noch fehlt, ist ein hinreichend genaues quantenchemisches Modell für die Schwingungsfrequenzen eines gelösten Peptids. Diese Aufgabe stellt zur Zeit ein aktives Forschungsgebiet dar. Zuletzt wurde das Schwingungsspektrum eines sogenanten “Photoschaltbaren”-Peptids simuliert. Mit Hilfe des dafür aufgestellten Hamiltonians ist man in der Lage spektroskopische Beobachtungen auf Konformationsänderungen direkt zu übertragen.
The development of novel drugs targeting GPCRs is of particular interest since modulation of subfamilies of this receptor class highly influences neurotransmission in the central nervous system. This study has focused on the development of ligands for the dopamine D3 receptor. The receptor belongs to the dopamine D2-like family among the biogenic amine binding GPCRs. The dopamine D3 receptor is involved in neurological and neuropsychiatric disorders such as Parkinson’s disease, schizophrenia and drug addiction. Due to its close structural similarity to the dopamine D2 receptor subtype, it is still a challenge to identify and further optimize new leads. Therefore an in vitro screening assay, which also allows elucidating comprehensive structure-affinity relationships, is required. In this investigation the implementation and evaluation of radioligand binding assays for human dopamine D2S and dopamine D3 receptors and for the related aminergic human histamine H1 receptor stably expressed in Chinese hamster ovary (CHO) cells has been performed. Saturation binding experiments with [³H]spiperone at dopamine D2S and D3 receptors and with [³H]mepyramine at histamine H1 receptors were carried out. The determined equilibrium dissociation constant of radioligands (Kd) and the total number of specific binding sites (Bmax) of the receptor membrane preparations were in good agreement with reference data. Inhibition constants (Ki) of reference ligands obtained in radioligand competition binding experiments at dopamine hD2S, hD3 and histamine H1 receptors validated the reliability and reproducibility of the assay. In order to discriminate agonists from antagonists, a GTP shift assay has been investigated for dopamine D2S and D3 receptors. In competition binding studies at dopamine D2S receptors the high- and low affinity state in the absence of the GTP analogue Gpp(NH)p has been recognized for the agonists pramipexole and the seleno analogue 54. In the presence of Gpp(NH)p a decrease in affinity, referred to as “GTP shift”, has been revealed for agonists at dopamine D2S and D3 receptors. An effect of Gpp(NH)p on dopamine D2S receptor binding has not been observed for the antagonists ST 198 and BP 897, while a reverse “GTP shift” has been noticed at the dopamine D3 receptor. For the development of novel ligands with high affinity and selectivity for dopamine D3 receptors, investigation in refined structure-affinity relationships (SAR) of analogues of the lead BP 897 has been performed. Replacement of the naphthalen-2-carboxamide of BP 897 by aryl amide residues (1 - 4) had a clear influence on affinity binding and selectivity for dopamine D3 receptors. Introduction of the benzo[b]thiophen-2-carboxamide (1) has markedly improved binding with subnanomolar affinity and enhanced selectivity for dopamine D3 receptors. Exchanging the aryl substituted basic alkanamine residue of 1 by a 1,2,3,4-tetrahydroisoquinoline moiety (6) emphasized the benefit of the 4-(2-methoxyphenyl) piperazine residue of BP 897 regarding dopamine D2 and D3 receptor affinities. The change of particular elements of BP 897 and the rearrangement of the amide functionality resulted in inverse amide compounds with new chemical properties. Moderate affinity binding data, as obtained for the isoindol-1-carbonyl compound 11, suggest that inverse amides provide a worthwhile new lead structure with a novel structural scaffold. A hybrid approach combining privileged scaffolds of histamine H1 receptor antagonists and fragments of dopamine D3 receptor-preferring ligands, related to BP 897and analogues has been investigated. Various benzhydrylpiperazine derivatives and related structures have shown moderate to high affinities for dopamine D3 receptors with the impressive enhancement of the cinnamide substituted bamipine-related hybrid 39, exhibiting the highest affinity and selectivity for dopamine D3 receptors. Improved affinity profiles of structural modified histamine H1 receptor antagonists for dopamine D2 and D3 receptors and a refined SAR has been achieved. A SAR of derivatives of the dopamine agonist pramipexole and the related etrabamine has been studied. The propargyl substituted etrabamine derivative 61 demonstrated highest affinity and selectivity. The ligand attracts attention since neuroprotective properties have been reported for the propargyl functionality. Further development resulted in the most promising compound 64, a cinnamide derivative with 4-fluoro substitution on the phenyl ring. Subnanomolar affinity and remarkable selectivity for dopamine D3 receptors has aroused particular interest in this ligand due to its development potential as a radioligand for PET studies. Radioligand binding studies in combination with virtual screening and different classification techniques of chemoinformatic methods resulted in further elucidation of SAR. New leads with novel chemical scaffolds have been found in the bicycle[2.2.1]heptane derivative 95 and the benzhydrylidene substituted pyrrolidindione 112 and can be further optimized by chemical modifications. The outcome of the studies provides the development of various novel high affine and dopamine D3 receptor selective ligands. Modifications of lead structures or application of chemoinformatic tools in combination with radioligand competition binding assays have resulted in new leads with different chemical scaffolds. Furthermore, a comprehensive insight into structure-affinity relationships of ligands at dopamine D3 receptors has been revealed. This refined SAR is valuable to develop more affine and selective drug candidates with a designed pharmacological receptor profile.
Compared to all other organisms with 1 to 3 heat stress transcription factors (Hsfs) or Hsf-related factors, plants have extraordinarily large Hsf families with more than 20 Hsfs. Plant Hsfs are classified into three classes according to their oligomerization domains which is built of hydrophobic heptad repeats (HR) in two parts, HR-A and HR-B. Both parts may be immediately adjacent (class B), or they are separated by insertion of 21 (class A) and 7 amino acid residues (class C). In plant Hsf family, detailed investigations are so far limited to Hsfs A1a, A2, A3, A4d, A9, and B1. They strongly indicate functional diversification to be the main reason for the coexistence of multiple Hsfs. As an example the functional triad of HsfA1a, HsfA2, and HsfB1 is essential for all three phases of the hs response, (i) the triggering of the response by HsfA1a as master regulator, (ii) the maintenance and high efficiency of hs gene transcription by cooperation of HsfA1a with Hsfs A2 and B1, and finally, (iii) the restoration of house-keeping gene transcription during the recovery phase mediated by HsfB1 in cooperation with house-keeping transcription factors. The results presented in this thesis for Hsfs A4 and A5 open completely different aspects of functional diversification and cooperation of Hsfs. HsfA4 and HsfA5 homooligomerize and bind to corresponding HSE motifs. But in contrast to the highly active HsfA4, HsfA5 is completely inactive as transcriptional activator. Yeast two hybrid and GST pull-down techniques showed that both Hsfs have strong tendency for heterooligomerization. Using fluorescence microscopy the HsfA4/A5 heterooligomers were found to localize in the nucleus. These complexes are transcriptionally inactive due to the impairment of DNA binding. The repressor function of HsfA5 requires only its OD and no additional factors, e.g. a putative co-repressor recruited by the C-terminal domain, are involved. Evidently, the repressor effect mainly results from the interference with the oligomeric state of HsfA4b, which is essential for efficient DNA binding and activator functions. EST database search revealed that plants have a single HsfA5 and usually two A4-type Hsfs. Using bioinformatics tools, Hsfs A4 and A5 were found to be phylogenetically closely related and clearly distinct from the other members of the Hsf family. On the basis of RT-PCR and Microarray data the representatives of the A4/A5 group are well expressed in different plant tissues albeit at very different levels which change with the developmental stages and stress conditions In rice and Arabidopsis, HsfA4 functions as an anti-apoptotic factor for stress induced oxidative damages. Based on my results, I hypothesize that HsfA5 functions as a novel type of selective repressor, regulating the function of A4-type Hsfs in plants. Considering the high sequence conservation with in plant Hsf family, it is tempting to speculate that this role of Hsf4/A5 pair is a fundamental feature of the Hsf system in plants.
We consider the theory of high temperature superconductivity from the viewpoint of a strongly correlated electron system. In particular, we discuss Gutzwiller projected wave functions, which incorporate strong correlations by prohibiting double occupancy in orbitals with strong on-site repulsion. After a general overview on high temperature superconductivity, we discuss Anderson’s resonating valence bond (RVB) picture and its implementation by renormalized mean field theory (RMFT) and variational Monte Carlo (VMC) techniques. In the following, we present a detailed review on RMFT and VMC results with emphasis on our recent contributions. Especially, we are interested in spectral features of Gutzwiller-Bogoliubov quasiparticles obtained by extending VMC and RMFT techniques to excited states. We explicitly illustrate this method to determine the quasiparticle weight and provide a comparison with angle resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). We conclude by summarizing recent successes and by discussing open questions, which must be solved for a thorough understanding of high temperature superconductivity by Gutzwiller projected wave functions.