Clustering
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- MeSH
- Alzheimerova nemoc patologie MeSH
- infekce pomalými viry klasifikace MeSH
- nemoci mozku diagnóza etiologie MeSH
- Publikační typ
- kazuistiky MeSH
Small hydrophobic gold nanoparticles with diameter lower than the membrane thickness can form clusters or uniformly distribute within the hydrophobic core of the bilayer. The coexistence of two stable phases (clustered and dispersed) indicates the energy barrier between nanoparticles. We calculated the distance dependence of the membrane-mediated interaction between two adjacent nanoparticles. In our model we consider two deformation modes: the monolayer bending and the hydroxycarbon chain stretching. Existence of an energy barrier between the clustered and the separated state of nanoparticles was predicted. Variation analysis of the membrane mechanical parameters revealed that the energy barrier between two membrane embedded nanoparticles is mainly the consequence of the bending deformation and not change of the thickness of the bilayer in the vicinity of nanoparticles. It is shown, that the forces between the nanoparticles embedded in the biological membrane could be either attractive or repulsive, depending on the mutual distance between them.
BACKGROUND AND OBJECTIVES: Recent studies fueled doubts as to whether all currently defined central disorders of hypersomnolence are stable entities, especially narcolepsy type 2 and idiopathic hypersomnia. New reliable biomarkers are needed, and the question arises of whether current diagnostic criteria of hypersomnolence disorders should be reassessed. The main aim of this data-driven observational study was to see whether data-driven algorithms would segregate narcolepsy type 1 and identify more reliable subgrouping of individuals without cataplexy with new clinical biomarkers. METHODS: We used agglomerative hierarchical clustering, an unsupervised machine learning algorithm, to identify distinct hypersomnolence clusters in the large-scale European Narcolepsy Network database. We included 97 variables, covering all aspects of central hypersomnolence disorders such as symptoms, demographics, objective and subjective sleep measures, and laboratory biomarkers. We specifically focused on subgrouping of patients without cataplexy. The number of clusters was chosen to be the minimal number for which patients without cataplexy were put in distinct groups. RESULTS: We included 1,078 unmedicated adolescents and adults. Seven clusters were identified, of which 4 clusters included predominantly individuals with cataplexy. The 2 most distinct clusters consisted of 158 and 157 patients, were dominated by those without cataplexy, and among other variables, significantly differed in presence of sleep drunkenness, subjective difficulty awakening, and weekend-week sleep length difference. Patients formally diagnosed as having narcolepsy type 2 and idiopathic hypersomnia were evenly mixed in these 2 clusters. DISCUSSION: Using a data-driven approach in the largest study on central disorders of hypersomnolence to date, our study identified distinct patient subgroups within the central disorders of hypersomnolence population. Our results contest inclusion of sleep-onset REM periods in diagnostic criteria for people without cataplexy and provide promising new variables for reliable diagnostic categories that better resemble different patient phenotypes. Cluster-guided classification will result in a more solid hypersomnolence classification system that is less vulnerable to instability of single features.
- MeSH
- idiopatická hypersomnie * diagnóza MeSH
- kataplexie * diagnóza MeSH
- lidé MeSH
- mladiství MeSH
- narkolepsie * diagnóza farmakoterapie MeSH
- poruchy nadměrné spavosti * diagnóza epidemiologie MeSH
- shluková analýza MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- Publikační typ
- časopisecké články MeSH
- pozorovací studie MeSH
T cell activation is initiated when ligand binding to the T cell receptor (TCR) triggers intracellular phosphorylation of the TCR-CD3 complex. However, it remains unknown how biophysical properties of TCR engagement result in biochemical phosphorylation events. Here, we constructed an optogenetic tool that induces spatial clustering of ζ-chain in a light controlled manner. We showed that spatial clustering of the ζ-chain intracellular tail alone was sufficient to initialize T cell triggering including phosphorylation of ζ-chain, Zap70, PLCγ, ERK and initiated Ca2+ flux. In reconstituted COS-7 cells, only Lck expression was required to initiate ζ-chain phosphorylation upon ζ-chain clustering, which leads to the recruitment of tandem SH2 domain of Zap70 from cell cytosol to the newly formed ζ-chain clusters at the plasma membrane. Taken together, our data demonstrated the biophysical relevance of receptor clustering in TCR signaling.
- MeSH
- aminokyselinové motivy MeSH
- buněčná membrána metabolismus MeSH
- Cercopithecus aethiops MeSH
- COS buňky MeSH
- cytosol metabolismus MeSH
- difuze MeSH
- fluorescenční spektrometrie MeSH
- fosforylace MeSH
- Jurkat buňky MeSH
- lidé MeSH
- optogenetika MeSH
- receptory antigenů T-buněk chemie metabolismus MeSH
- shluková analýza MeSH
- signální transdukce * MeSH
- světlo MeSH
- tyrosinkinasa p56(lck), specifická pro lymfocyty metabolismus MeSH
- vápník metabolismus MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Antenna protein aggregation is one of the principal mechanisms considered effective in protecting phototrophs against high light damage. Commonly, it is induced, in vitro, by decreasing detergent concentration and pH of a solution of purified antennas; the resulting reduction in fluorescence emission is considered to be representative of non-photochemical quenching in vivo. However, little is known about the actual size and organization of antenna particles formed by this means, and hence the physiological relevance of this experimental approach is questionable. Here, a quasi-single molecule method, fluorescence correlation spectroscopy (FCS), was applied during in vitro quenching of LHCII trimers from higher plants for a parallel estimation of particle size, fluorescence, and antenna cluster homogeneity in a single measurement. FCS revealed that, below detergent critical micelle concentration, low pH promoted the formation of large protein oligomers of sizes up to micrometers, and therefore is apparently incompatible with thylakoid membranes. In contrast, LHCII clusters formed at high pH were smaller and homogenous, and yet still capable of efficient quenching. The results altogether set the physiological validity limits of in vitro quenching experiments. Our data also support the idea that the small, moderately quenching LHCII oligomers found at high pH could be relevant with respect to non-photochemical quenching in vivo.
- MeSH
- chlorofyl chemie genetika účinky záření MeSH
- fluorescence MeSH
- fluorescenční spektrometrie MeSH
- fotosyntéza genetika MeSH
- fotosystém II (proteinový komplex) genetika účinky záření MeSH
- fototrofní procesy genetika MeSH
- homeodoménový protein Antennapedia chemie genetika MeSH
- koncentrace vodíkových iontů MeSH
- proteinové agregáty genetika MeSH
- shluková analýza MeSH
- světlo škodlivé účinky MeSH
- světlosběrné proteinové komplexy chemie genetika MeSH
- tylakoidy chemie genetika účinky záření MeSH
- zeaxanthiny genetika MeSH
- Publikační typ
- časopisecké články MeSH
Cílem této studie bylo představit české veřejnosti návrh clusteringu a switchingu v testu verbální fluence (VF), adaptovat vybrané klasifikace do českého prostředí a posoudit jejich relevanci. Článek se zabývá hodnocením uspořádání slov do celků (tzv. clusterů) a plynulosti přepínání mezi nimi (switching). Tento v zahraničí rozšířený přístup k analýze protokolů VF nebyl doposud v češtině systematizován. Čtenář je seznámen s teoretickým pozadím hodnocení clusterů a switchů ve fonologické verzi (PVF) i kategoriální verzi (SVF) a některými vybranými klasifikacemi – např. Troyer et al. (1997), Abwender et al. (2001), Libon et al. (2009) či Tallberg et al. (2011). Klasifikace Troyerové et al. (1997), která je celosvětově nejcitovanější, byla převzata a autoři článku se vyjádřili k jednotlivým pravidlům z pohledu českého jazyka i kulturního prostředí (Studie 1). Ve Studii 2 byly u deseti vybraných protokolů dvěma posuzovateli oskórovány fonematické clustery v PVF a sémantické clustery v SVF. Vypočtená shoda posuzovatelů ukázala v obou případech na dobrou až výbornou shodu. Jedná se o velmi slibný, nicméně stále teoretický koncept, jehož aplikace do praxe si žádá další zkoumání.
The main goal of this study was to introduce the evaluation procedure in Verbal fluency task – clustering and switching – to the Czech public, to adapt this procedure to the Czech language and to judge its relevance. The review focuses on the way of arranging the words into the clusters (so called clustering) and switching between them. This procedure is extended in foreign research but it has not yet been systematically adapted in the Czech context. In the article the theoretical background of clustering and switching in phonological verbal fluency (PVF) and also in semantic verbal fluency (SVF) is introduced and few classifications of clustering are described – e.g. Troyer et al. (1997), Abwender et al. (2001), Libon et al. (2009) and Tallberg et al. (2011). In Study 1, the most cited classification by Troyer et al. (1997) is adapted to the Czech language and the differences between the original version and Czech adaptation are discussed. In Study 2, ten protocols were rated by two raters and the inter-rater reliability was calculated. The value of Cohen,s kappa showed moderate to excellent agreement. This approach is very promising but it requires further research.
- MeSH
- fonetika MeSH
- lingvistika metody MeSH
- neuropsychologické testy MeSH
- sémantika MeSH
- verbální chování klasifikace MeSH
- Publikační typ
- práce podpořená grantem MeSH
It is unclear how dietary, physical activity and sedentary behaviors co-occur in school-aged children. We investigated the clustering of energy balance-related behaviors and whether the identified clusters were associated with weight status. Participants were 6- to 9-year-old children (n = 63,215, 49.9% girls) from 19 countries participating in the fourth round (2015/2017) of the World Health Organization (WHO) European Childhood Obesity Surveillance Initiative. Energy balance-related behaviors were parentally reported. Weight and height were objectively measured. We performed cluster analysis separately per group of countries (North Europe, East Europe, South Europe/Mediterranean countries and West-Central Asia). Seven clusters were identified in each group. Healthier clusters were common across groups. The pattern of distribution of healthy and unhealthy behaviors within each cluster was group specific. Associations between the clustering of energy balance-related behaviors and weight status varied per group. In South Europe/Mediterranean countries and East Europe, all or most of the cluster solutions were associated with higher risk of overweight/obesity when compared with the cluster 'Physically active and healthy diet'. Few or no associations were observed in North Europe and West-Central Asia, respectively. These findings support the hypothesis that unfavorable weight status is associated with a particular combination of energy balance-related behavior patterns, but only in some groups of countries.
- MeSH
- cvičení MeSH
- dítě MeSH
- energetický metabolismus fyziologie MeSH
- lidé MeSH
- obezita epidemiologie MeSH
- shluková analýza MeSH
- Světová zdravotnická organizace MeSH
- zdravé chování * MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
