Browsing by Subject "DISSOCIATION"

Sort by: Order: Results:

Now showing items 1-11 of 11
  • Rozov, Stanislav V.; Zant, Janneke; Gurevicius, Kestutis; Porkka-Heiskanen, Tarja; Panula, Pertti (2016)
    Aim: Under natural conditions diurnal rhythms of biological processes of the organism are synchronized with each other and to the environmental changes by means of the circadian system. Disturbances of the latter affect hormonal levels, sleep-wakefulness cycle and cognitive performance. To study mechanisms of such perturbations animal models subjected to artificial photoperiods are often used. The goal of current study was to understand the effects of circadian rhythm disruption, caused by a short light-dark cycle regime, on activity of the cerebral cortex in rodents. Methods: We used electroencephalogram to assess the distribution of vigilance states, perform spectral analysis, and estimate the homeostatic sleep drive. In addition, we analyzed spontaneous locomotion of C57BL/6J mice under symmetric, 22-, 21-, and 20-h-long light-dark cycles using video recording and tracking methods. Results and Conclusions: We found that shortening of photoperiod caused a significant increase of slow wave activity during non-rapid eye movement sleep suggesting an elevation of sleep pressure under such conditions. While the rhythm of spontaneous locomotion was completely entrained by all light-dark cycles tested, periodic changes in the power of the theta- and gamma-frequency ranges during wakefulness gradually disappeared under 22- and 21-h-long light-dark cycles. This was associated with a significant increase in the theta-gamma phase-amplitude coupling during wakefulness. Our results thus provide deeper understanding of the mechanisms underlying the impairment of learning and memory retention, which is associated with disturbed circadian regulation.
  • Miliutina, Elena; Guselnikova, Olga; S. Soldatova, Natalia; Bainova, Polina; Elashnikov, Roman; Fitl, Přemysl; Kurten, Theo; S. Yusubov, Mekhman; Švorčík, Václav; Valiev, Rashid; M. Chehimi, Mohamed; Lyutakov, Oleksiy; S. Postnikov, Pavel (2020)
    Plasmon-assisted transformations of organic compounds represent a novel opportunity for conversion of light to chemical energy at room temperature. However, the mechanistic insights of interaction between plasmon energy and organic molecules is still under debate. Herein, we proposed a comprehensive study of the plasmon-assisted reaction mechanism using unsymmetric iodonium salts (ISs) as an organic probe. The experimental and theoretical analysis allow us to exclude the possible thermal effect or hot electron transfer. We found that plasmon interaction with unsymmetrical ISs led to the intramolecular excitation of electron followed by the regioselective cleavage of C–I bond with the formation of electron-rich radical species, which cannot be explained by the hot electron excitation or thermal effects. The high regioselectivity is explained by the direct excitation of electron to LUMO with the formation of a dissociative excited state according to quantum-chemical modeling, which provides novel opportunities for the fine control of reactivity using plasmon energy.
  • Roet, Sander; Daub, Christopher; Riccardi, Enrico (2021)
    We propose to analyze molecular dynamics (MD) output via a supervised machine learning (ML) algorithm, the decision tree. The approach aims to identify the predominant geometric features which correlate with trajectories that transition between two arbitrarily defined states. The data-driven algorithm aims to identify these features without the bias of human “chemical intuition”. We demonstrate the method by analyzing the proton exchange reactions in formic acid solvated in small water clusters. The simulations were performed with ab initio MD combined with a method to efficiently sample the rare event, path sampling. Our ML analysis identified relevant geometric variables involved in the proton transfer reaction and how they may change as the number of solvating water molecules changes.
  • Adam, J.; Brucken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Kral, J.; Mieskolainen, M. M.; Rak, J.; Snellman, T. W.; Trzaska, W. H.; Räsänen, Sami Sakari; The ALICE collaboration (2015)
    We report the first measurement at the LHC of coherent photoproduction of rho(0) mesons in ultra-peripheral Pb-Pb collisions. The invariant mass and transverse momentum distributions for rho(0) production are studied in the pi(+)pi(-) decay channel at mid-rapidity. The production cross section in the rapidity range vertical bar y vertical bar <0.5 is found to be d sigma/dy = 425 +/- 10 (stat.) (+42)(-50) (sys.) mb. Coherent rho(0) production is studied with and without requirement of nuclear breakup, and the fractional yields for various breakup scenarios are presented. The results are compared with those from lower energies and with model predictions.
  • Riekki, Tapani; Svedholm-Häkkinen, Annika M.; Lindeman, Marjaana (2018)
    Using the empathizing-systemizing theory as our framework, we investigated how people with high self-reported empathizing (having good social skills and being interested in people) and systemizing (being interested in physical things and processes) differ in the social information processing of emotionally negative photographs of people during “spontaneous watching” and emotional and cognitive empathy tasks. Empathizers evaluated the pictures as more emotionally touching and the reactions in the photographs more understandable than the systemizers. Compared to the empathizers, systemizers had stronger activations in the posterior cingulate cortex, an area related to cognitive empathy, as well as in the left superior temporal gyrus and middle frontal gyrus when watching emotional photographs spontaneously. During guided emotional and cognitive empathy tasks, these differences disappeared. However, during the emotional empathy task, higher systemizing was associated with weaker activation of the right inferior frontal gyrus /insula. Furthermore, during emotional and cognitive empathy tasks, empathizing was related to increased activations of the amygdala which were in turn related to higher behavioral ratings of emotional and cognitive empathy. The results suggest that empathizers and systemizers engage in social information processing differently: systemizers in more cognitive terms and empathizers with stronger automatic emotional reactions.
  • Lindeman, Marjaana; Koirikivi, Iivo; Lipsanen, Jari (2018)
    Research on empathy has increased rapidly during the last decades but brief assessment methods are not easily available. The aim was to develop a test for affective empathic reactions which would be simple to translate into different languages, easy to use in a variety of research settings, and which would catch the empathic reactions at the moment they arise. We describe the development and validation of the Pictorial Empathy Test (PET) in three studies (Study 1, N = 91: Study 2, N = 2,789: and Study 3, N = 114). The PET includes seven photographs about distressed individuals and the participants are asked to rate on a 5-point scale how emotionally moving they find the photograph. The results indicated that the PET displayed a unitary factor structure and it had high internal consistency and good seven-month test-retest reliability. In addition, the results supported convergent and discriminant validity of the test. The results suggest that the PET is a useful addition to the prevailing methods for assessing affective empathy.
  • Santos-Perez, Isaac; Charro, Diego; Gil-Carton, David; Azkargorta, Mikel; Elortza, Felix; Bamford, Dennis H.; Oksanen, Hanna M.; Abrescia, Nicola G. A. (2019)
    The vertical double beta-barrel major capsid protein (MCP) fold, fingerprint of the PRD1-adeno viral lineage, is widespread in many viruses infecting organisms across the three domains of life. The discovery of PRD1-like viruses with two MCPs challenged the known assembly principles. Here, we present the cryo-electron microscopy (cryo-EM) structures of the archaeal, halophilic, internal membrane-containing Haloarcula californiae icosahedral virus 1 (HCIV-1) and Haloarcula hispanica icosahedral virus 2 (HHIV-2) at 3.7 and 3.8 angstrom resolution, respectively. Our structures reveal proteins located beneath the morphologically distinct two- and three-tower capsomers and homopentameric membrane proteins at the vertices that orchestrate the positioning of pre-formed vertical single beta-barrel MCP heterodimers. The cryo-EM based structures together with the proteomics data provide insights into the assembly mechanism of this type of viruses and into those with membrane-less double beta-barrel MCPs.
  • Blum, Markus; Feil, Christoph M.; Nieger, Martin; Gudat, Dietrich (2021)
    A diphosphine with an unsupported PP bond connecting two carbon-free "inorganic" 1,3,2,4,5-diazaphosphadisilolidine rings was prepared by reductive coupling of a P-chloro-substituted monocyclic precursor molecule. VT-EPR studies revealed that the diphosphine exists in solution, like other compounds of this kind, in dynamic equilibrium with the corresponding phosphinyl radicals. Determination of the radical concentration from the EPR spectra permitted to calculate thermochemical parameters for the homolytic PP bond fission. The results disclose that both the enthalpy and entropy of dissociation are higher than in topologically related bi(diazaphospholidines). The impact of the entropy term allows explaining that, regardless of the presence of an energetically rather stable PP bond, the onset of dissociation is observable even at ambient temperature. Irradiation experiments showed that radical formation cannot only be induced thermally, but also by photolysis.
  • Eesmaa, Ave; Yu, Li-Ying; Göös, Helka; Nõges, Kristofer; Kovaleva, Vera; Hellman, Maarit; Zimmermann, Richard; Jung, Martin; Permi, Perttu; Varjosalo, Markku; Lindholm, Paivi; Saarma, Mart (2021)
    Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER)-stress-regulated protein exhibiting cytoprotective properties through a poorly understood mechanism in various in vitro and in vivo models of neuronal and non-neuronal damage. Although initially characterized as a secreted neurotrophic factor for midbrain dopamine neurons, MANF has recently gained more interest for its intracellular role in regulating the ER homeostasis, including serving as a cofactor of the chaperone glucose-regulated protein 78 (GRP78). We aimed for a better understanding of the neuroprotective mechanisms of MANF. Here we show for the first time that MANF promotes the survival of ER-stressed neurons in vitro as a general unfolded protein response (UPR) regulator, affecting several UPR pathways simultaneously. Interestingly, MANF does not affect naive neurons. We hypothesize that MANF regulates UPR signaling toward a mode more compatible with neuronal survival. Screening of MANF interacting proteins from two mammalian cell lines revealed a conserved interactome of 15 proteins including several ER chaperones such as GRP78, GRP170, protein disulfide isomerase family A member 1, and protein disulfide isomerase family A member 6. Further characterization confirmed previously published finding that MANF is a cofactor of GRP78 interacting with its nucleotide binding domain. Using microscale thermophoresis and nuclear magnetic resonance spectroscopy, we discovered that MANF is an ATP binding protein and that ATP blocks the MANF-GRP78 interaction. Interestingly, functional analysis of the antiapoptotic properties of MANF mutants in cultured neurons revealed divergent roles of MANF as a GRP78 cofactor and as an antiapoptotic regulator of UPR. We conclude that the co-factor type interaction with GRP78 is dispensable for the survival-promoting activity of MANF in neurons.
  • Zwir, Igor; Del-Val, Coral; Arnedo, Javier; Pulkki-Råback, Laura; Konte, Bettina; Yang, Sarah S.; Romero-Zaliz, Rocio; Hintsanen, Mirka; Cloninger, Kevin M.; Garcia, Danilo; Svrakic, Dragan M.; Lester, Nigel; Rozsa, Sandor; Mesa, Alberto; Lyytikainen, Leo-Pekka; Giegling, Ina; Kahonen, Mika; Martinez, Maribel; Seppala, Ilkka; Raitoharju, Emma; de Erausquin, Gabriel A.; Mamah, Daniel; Raitakari, Olli; Rujescu, Dan; Postolache, Teodor T.; Gu, C. Charles; Sung, Joohon; Lehtimäki, Terho; Keltikangas-Jarvinen, Liisa; Cloninger, C. Robert (2021)
    Phylogenetic, developmental, and brain-imaging studies suggest that human personality is the integrated expression of three major systems of learning and memory that regulate (1) associative conditioning, (2) intentionality, and (3) self-awareness. We have uncovered largely disjoint sets of genes regulating these dissociable learning processes in different clusters of people with (1) unregulated temperament profiles (i.e., associatively conditioned habits and emotional reactivity), (2) organized character profiles (i.e., intentional self-control of emotional conflicts and goals), and (3) creative character profiles (i.e., self-aware appraisal of values and theories), respectively. However, little is known about how these temperament and character components of personality are jointly organized and develop in an integrated manner. In three large independent genome-wide association studies from Finland, Germany, and Korea, we used a data-driven machine learning method to uncover joint phenotypic networks of temperament and character and also the genetic networks with which they are associated. We found three clusters of similar numbers of people with distinct combinations of temperament and character profiles. Their associated genetic and environmental networks were largely disjoint, and differentially related to distinct forms of learning and memory. Of the 972 genes that mapped to the three phenotypic networks, 72% were unique to a single network. The findings in the Finnish discovery sample were blindly and independently replicated in samples of Germans and Koreans. We conclude that temperament and character are integrated within three disjoint networks that regulate healthy longevity and dissociable systems of learning and memory by nearly disjoint sets of genetic and environmental influences.
  • Bhattarai, Mamata; Valoppi, Fabio; Hirvonen, Sami-Pekka; Hietala, Sami; Kilpelainen, Petri; Aseyev, Vladimir; Mikkonen, Kirsi S. (2020)
    The demand for naturally derived, functional and cost-effective raw materials for various food applications is escalating. Spruce wood is a sustainable and abundant, but underutilized source of novel hydrocolloids-galactoglucomannans (GGM). Pressurized-hot water extracted GGM with an intermediate molar mass are hypothesized to form colloidal solutions. To design superior quality products from GGM, an understanding of their colloidal stability and their potential effect in multiphasic systems is required. The present study addresses the functionality of GGM by characterizing their properties in a bi-phasic system, and for the first time, their time-dependent colloidal stability at different extrinsic conditions- pH, ionic strength and after the application of high-intensity mechanical shearing. Amongst the conditions studied, the colloidal stability of aqueous GGM solution was highly pH dependent. The results showed that an intermediate molar mass polysaccharide like GGM formed inter-/intra molecular assemblies, which grew over time, depending on the composition and processing of the aqueous medium. The molecular dispersion of GGM and their dynamic behavior was also compared to solutions of known food hydrocolloids-gum Arabic and hydroxypropylmethyl cellulose. The observed solution properties explain the hydmcolloid functionality of GGM and contribute to design of colloidal polysaccharide systems in food application.