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Search Results: 1 - 10 of 226 matches for " Margit Paparo "
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Investigation of Rotational Splitting in the Pulsating White Dwarf GD 154
Zsofia Bognar,Margit Paparo
Physics , 2013,
Abstract: We observed the ZZ Ceti star GD 154 over a whole season at the mountain station of Konkoly Observatory. Our long time base allowed to detect the sign of rotational triplets around the independent modes. To check whether these can be real detections we made a test on our data set. We searched for characteristic spacing values performing Fourier analysis of numerous peaks determined around five frequencies in the main pulsation region. The analysis revealed regular peak spacings with separations around 3.7 and 2.6 microHz. These values are in accordance with the ones determined by consecutive prewhitening of Whole Earth Telescope observations.
Neuropeptide Receptors in Pain Circuitries: Useful Targets for CNS Imaging with Non-Peptide Ligands Suitable for PET?  [PDF]
Margit Pissarek
World Journal of Neuroscience (WJNS) , 2014, DOI: 10.4236/wjns.2014.44040
Abstract:

Neuropeptide receptors of the brain and spinal cord are parts of the pain circuits targeted by analgesic drugs. Some of these receptors have been found in the central nervous system as well as in intracranial vascular structures and achieved revival of attention because of their role in acute and chronic pain syndromes. A number of them are of high clinical relevance for e.g. migraine. Others participate in symptoms of rare diseases like amyotrophic lateral sclerosis. Here we will focus on five of the neuropeptide receptors and their non-peptide ligands potentially or already successfully used as PET probes. Opioid receptors and neurotensin receptors are known to mediate analgesic actions. Bradykinin and calcitonin gene-related peptide (CGRP) receptors are known to be involved in the regulation of vascular tone and inflammatory responses, and neurokinin receptors play a role in the occurrence of pain perception in a rather indirect manner. Most experiences as PET tracers have been gathered with opioid receptor ligands and neurokinin receptor ligands. The most innovative fields revealed by the studies summarized in this report are the ligands of κ opioid receptors and CGRP receptors for which a first PET tracer was presented recently.

Potential PET Ligands for Imaging of Cerebral VPAC and PAC Receptors: Are Non-Peptide Small Molecules Superior to Peptide Compounds?  [PDF]
Margit Pissarek
World Journal of Neuroscience (WJNS) , 2015, DOI: 10.4236/wjns.2015.55036
Abstract: Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) have been known for decades to mediate neuroendocrine and vasodilative actions via G-protein-coupled receptors of Class B. These are targets of imaging probes for positron emission tomography (PET) or single photon emission tomography (SPECT) in tumor diagnostics and tumor grading. However, they play only a subordinate role in the development of tracers for brain imaging. Difficulties in development of non-peptide ligands typical for cerebral receptors of PACAP and VIP are shared by all members of Class B receptor family. Essential landmarks have been confirmed for understanding of structural details of Class B receptor molecular signalling during the last five years. High relevance in the explanation of problems in ligand development for these receptors is admitted to the large N-terminalectodomain markedly different from Class A receptor binding sites and poorly suitable as orthosteric binding sites for the most small-molecule compounds. The present study is focused on the recently available receptor ligands for PAC1, VPAC1 and VPAC2 receptors as well as potential small-molecule lead structures suitable for use in PET or SPECT. Recently, biaryl, cyanothiophene and pentanamide structures with affinities in nM-range have been proposed as non-peptide ligands at VPAC1 and VPAC2 receptors. However, most of these ligands have been classified as non-competitive related to the orthosteric binding site of endogenous peptide ligands of VPAC receptors. For PAC1 receptors have been identified hydrazide compounds for which an inhibitory and potentially competitive mechanism of receptor binding has been postulated based on molecular docking studies.
Small Molecule-Assisted PET: Approaches to Imaging of Conformational Diseases of the Brain  [PDF]
Margit Pissarek
World Journal of Neuroscience (WJNS) , 2017, DOI: 10.4236/wjns.2017.71010
Abstract: PET (positron emission tomography) in vivo imaging of cerebral conformational diseases is essentially based on non-peptide small molecule ligands used to detect early alterations in peptide secondary structures and subsequent accumulation of aberrant oligomers and protein deposits involved in progressive neurodegeneration, cognitive and movement disorders. In this article, an overview is given about tracers currently available and lead structures of potential PET probes for detection of?β-amyloid (Aβ), tau protein, α-synuclein, constitutive (PrPc) and infectious isoforms (PrPsc) of prions (proteinaceous infectious particles) as imaging targets. Whereas the styrylpyridine derivative florbetapir, approved for clinical applications, the stilbene derivative florbetaben and the benzoxazole derivative BF227 show high affinity binding to Aβ, preclinical investigations promise improved pharmacokinetics for benzoimidazothiazoles, aryloxazoles and benzofuran derivatives. Tau protein imaging based clinically, presently, on the pyridine-pyridoindole T807 has got new incentives following identification of a series of pyrrolopyridine quinolines and pharmacokinetic improvements of fluoropropoxy quinolines including for instance THK-5351. The pyridine isoquinoline MK6240 is involved now in clinical trials. Most forward-looking efforts apply to small molecule ligands of α-synuclein, which are expected to permit a breakthrough in differential diagnostics of Parkinson-related dementia and Lewy body diseases. However, at the moment the proposed lead structures are in affinity and blood brain barrier delivery properties below the possibilities of Aβ?and tau protein ligands. This is the case also for potential tracers of prion proteins.
Activated Microglia in the Brain: Mitochondrial and Cell Membrane-Associated Targets for Positron Emission Tomography  [PDF]
Margit Pissarek
World Journal of Neuroscience (WJNS) , 2018, DOI: 10.4236/wjns.2018.81006
Abstract: The emission tomographic imaging of activated microglia in the brain moves into the focus of neuroscientific research with increasing recognition of contributions of early inflammatory processes to neurodegenerative, traumatic, cancerous and infectious diseases of the brain. Whereas the mitochondrial isoform of the 18 kDa translocator protein (TSPO1) has been the main cellular target for positron emission tomography (PET) of this type of cells for decades, alternative marker proteins in the plasma membrane of microglia challenge efforts in ligand development, recently. The present report includes PET approaches using the chemokine receptor CX3CR1 and the FR2 folate receptor in parallel to small molecule PET tracers available for in vivo visualization of the “classical” target TSPO1. It compares first and second generation of TSPO1 ligands as well as new compounds like the tetrahydrocarbazole [18F]GE-180 and the quinazoline [11C]ER176 presumed to reduce polymorphism-related inter-subject variations, with allosteric ligands for the chemokine receptor CX3CR1 and with radio labelled folate conjugates targeting the folate “cargo” receptor FR1 and the FR2 receptor characteristic for anti-inflammatory M2 microglia.
Non-peptide ligands in the characterization of peptide receptors at the interface between neuroendocrine and mental diseases  [PDF]
Margit Pissarek, Ulrich Disko
World Journal of Neuroscience (WJNS) , 2013, DOI: 10.4236/wjns.2013.32014
Abstract:

Hypothalamic receptors for neuropeptide Y, melaninconcentrating hormone, melanocortins and orexins/ hypocretins as well as for the downstream signaling corticotrophic factor have been discussed broadly for their influence on food intake and reward but also on several psychiatric disorders. For the development of non-peptide ligands for the in vivo detection of alterations in density and affinity of such G-protein coupled (GPCRs) peptide receptors the requirements to affinity and pharmacokinetics have been shifted to thresholds markedly distict from classical GPCRs to dissociation constants < 0.5 nM, partition coefficients log P < 3.5 and transcellular transport ratios, e.g. for the permeability glycoprotein transporter, below 3. Nevertheless, a multitude of compounds has been reported originally as potential therapeutics in the treatment of obesity among which some are suitable candidates for labeling as PET or SPECT-tracers providing receptor affinities even below 0.1 nM. These could be unique tools not only for better understanding of the mechanism of obesity but also for investigations of extrahypothalamic role of “feeding receptors” at the interface between neuroendocrine and mental diseases.

Steps to the Reopening of an Interdisciplinary Journal Club—Austrian Experiences  [PDF]
Margit Eidenberger, Sylvia ?hlinger
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.717246
Abstract: Journal Clubs are one of the methods for continuing professional development in defined working units and have proved to be an effective teaching tool. A Journal Club introduced in 2011 for the University of Applied Sciences for Health Professions Upper Austria had limited success and was discontinued after 18 months. Searching for improvements, an online survey addressing the needs and expectations of the university staff was conducted. Results showed that the majority of the respondents (98%) are interested in attending a JC in the future. The new JC should take place between 3 and 5 pm. The main reasons for not participating in the former JC were other professional obligations and no time for preparation. Critical evaluation of studies should be the main target for further capacity building realised in the future. It is planned to reopen the JC with the knowledge gained.
Monitoring a high--amplitude Delta Sct star for 152 days: discovery of 12 additional modes and modulation effects in the light curve of CoRoT 101155310
Ennio Poretti,Monica Rainer,Werner W. Weiss,Zsofia Bognar,Andy Moya,Ewa Niemczura,Juan Carlos Suarez,Michel Auvergne,Annie Baglin,Frederic Baudin,Jozsef M. Benko,Jonas Debosscher,Rafa Garrido,Luciano Mantegazza,Margit Paparo
Physics , 2011, DOI: 10.1051/0004-6361/201016045
Abstract: The detection of small-amplitude nonradial modes in high-amplitude Delta Sct (HADS) variables has been very elusive until at least five of them were detected in the light curve of V974 Oph obtained from ground-based observations. The combination of radial and nonradial modes has a high asteroseismic potential, thanks to the strong constraints we can put in the modelling. The continuous monitoring of ASAS 192647-0030.0=CoRoT 101155310 (P=0.1258 d, V=13.4) ensured from space by the CoRoT (Convection, Rotation and planetary Transits) mission constitutes a unique opportunity to exploit such potential. The 22270 CoRoT measurements were performed in the chromatic mode. They span 152 d and cover 1208 consecutive cycles. After the correction for one jump and the long-term drift, the level of the noise turned out to be 29 micromag. The phase shifts and amplitude ratios of the coloured CoRoT data, the HARPS spectra, and the period-luminosity relation were used to determine a self-consistent physical model. In turn, it allowed us to model the oscillation spectrum, also giving feedback on the internal structure of the star. In addition to the fundamental radial mode f1=7.949 c/d with harmonics up to 10f1, we detected 12 independent terms. Linear combinations were also found and the light curve was solved by means of 61 frequencies (smallest amplitude 0.10 mmag). The newest result is the detection of a periodic modulation of the f1 mode (triplets at +/-0.193 c/d centred on f1 and 2f1), discussed as a rotational effect or as an extension of the Blazhko effect to HADS stars. The physical model suggests that CoRoT 101155310 is an evolved star, with a slight subsolar metallic abundance, close to the terminal age main sequence. All the 12 additional terms are identified with mixed modes in the predicted overstable region.
CoRoT light curves of RR Lyrae stars. CoRoT 101128793: long-term changes in the Blazhko effect and excitation of additional modes
Ennio Poretti,Margit Paparo,Magali Deleuil,Merieme Chadid,Katrien Kolenberg,Robert Szabo,Jozsef M. Benko,Eric Chapellier,Elisabeth Guggenberger,Jean-Francois Le Borgne,Florent Rostagni,Herve Trinquet,Michel Auvergne,Annie Baglin,Luis M. Sarro,Werner W. Weiss
Physics , 2010, DOI: 10.1051/0004-6361/201014941
Abstract: The CoRoT (Convection, Rotation and planetary Transits) space mission provides a valuable opportunity to monitor stars with uninterrupted time sampling for up to 150 days at a time. The study of RR Lyrae stars, performed in the framework of the Additional Programmes belonging to the exoplanetary field, will particularly benefit from such dense, long-duration monitoring. The Blazhko effect in RR Lyrae stars is a long-standing, unsolved problem of stellar astrophysics. We used the CoRoT data of the new RR Lyrae variable CoRoT 101128793 (f0=2.119 c/d, P=0.4719296 d) to provide us with more detailed observational facts to understand the physical process behind the phenomenon. The CoRoT data were corrected for one jump and the long-term drift. We applied different period-finding techniques to the corrected timeseries to investigate amplitude and phase modulation. We detected 79 frequencies in the light curve of CoRoT 101128793. They have been identified as the main frequency f0, and its harmonics, two independent terms, the terms related to the Blazhko frequency, and several combination terms. A Blazhko frequency fB=0.056 c/d and a triplet structure around the fundamental radial mode and harmonics were detected, as well as a long-term variability of the Blazhko modulation. Indeed, the amplitude of the main oscillation is decreasing along the CoRoT survey. The Blazhko modulation is one of the smallest observed in RR Lyrae stars. Moreover, the additional modes f1=3.630 and f2=3.159 c/d are detected. Taking its ratio with the fundamental radial mode into account, the term f1 could be the identified as the second radial overtone. Detecting of these modes in horizontal branch stars is a new result obtained by CoRoT.
L'homme comme expression de l'inconditionné dans la nature
Ruffing, Margit;
Trans/Form/A??o , 2009, DOI: 10.1590/S0101-31732009000100003
Abstract: in the anthropology from a pragmatic point of view, kant answers the question what human beings are in a descriptive and empirical way, characterizing the phenomenon "human being" as a member of the human community under social and cultural conditions. in the second part of the critique of judgment, however, kant tries to explain the noumenal dimension of the human being, based on the "conclusion" from moral teleology to a final purpose (see aa 05: 455). this argument has already been present in the human faculty of reason from its earlierst germination, and it develops more and more during the progressive cultivation of this faculty (see aa 05: 458). to point out the relationship between the "methodology of the teleological power of judgment" and the didactic function of the anthropology can help to understand the idea of man as a final purpose and as an aim requiring nothing else as condition of its possibility, thereby expressing the unconditional within the limits of sensual nature.
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