Microtubule stabilization specifies initial neuronal polarization

Axon formation is the initial step in establishing neuronal polarity. We examine here the role of microtubule dynamics in neuronal polarization using hippocampal neurons in culture. We see increased microtubule stability along the shaft in a single neurite before axon formation and in the axon of morphologically polarized cells. Loss of polarity or formation of multiple axons after manipulation of neuronal polarity regulators, synapses of amphids defective (SAD) kinases, and glycogen synthase kinase-3β correlates with characteristic changes in microtubule turnover. Consistently, changing the microtubule dynamics is sufficient to alter neuronal polarization. Application of low doses of the microtubule-destabilizing drug nocodazole selectively reduces the formation of future dendrites. Conversely, low doses of the microtubule-stabilizing drug taxol shift polymerizing microtubules from neurite shafts to process tips and lead to the formation of multiple axons. Finally, local stabilization of microtubules using a photoactivatable analogue of taxol induces axon formation from the activated area. Thus, local microtubule stabilization in one neurite is a physiological signal specifying neuronal polarization

Predicted as observed? How to identify empirically adequate theoretical constructs

The identification of an empirically adequate theoretical construct requires determining whether a theoretically predicted effect is sufficiently similar to an observed effect. To this end, we propose a simple similarity measure, describe its application in different research designs, and use computer simulations to estimate the necessary sample size for a given observed effect. As our main example, we apply this measure to recent meta-analytical research on precognition. Results suggest that the evidential basis is too weak for a predicted precognition effect of d = 0.20 to be considered empirically adequate. As additional examples, we apply this measure to object-level experimental data from dissonance theory and a recent crowdsourcing hypothesis test, as well as to meta-analytical data on the correlation of personality traits and life outcomes.Die Autor*innen schlagen ein simples Ähnlichkeitsmaß vor, beschreiben seine Anwendung in verschiedenen Forschungsdesigns und verwenden Computersimulationen, um die erforderliche Stichprobengröße für einen bestimmten beobachteten Effekt zu schätzen

Laserspektroskopische Untersuchungen an Halogenarenen mit REMPI- und MATI-Spektroskopie

Die REMPI-Spektroskopie wie auch die MATI-Spektroskopie sind sehr präzise Methoden zur Messung elektronisch angeregter Zustände (REMPI) und des kationischen Grundzustands (MATI) von Molekülen. Die (1+1’)MATI-Spektroskopie kombiniert beide Spektroskopiearten, so dass sich eine zweidimensionale Methode ergibt, mit der sich Aussagen über Geometrieänderungen von Molekülen während der Anregung und Ionisierung machen lassen. Zusätzlich liefert diese Methode sehr genaue Werte der Anregungs- und Ionisierungsenergie. Insbesondere die Ionisierungsenergie ist eine der wichtigsten thermodynamischen Größen. Im Rahmen dieser Arbeit wurden 1,2,3-halogensubstituierte Benzole (1,2,3-Trichlorbenzol, 1,3-Dichlor-2-fluorbenzol, 1-Chlor-2,6-difluorbenzol) und 1,3,5-Trichlorbenzol untersucht. Von Interesse waren dabei der Einfluss des Substitutionsmusters auf die Anregungs- und Ionisierungsenergie, sowie die Geometrieänderungen, die durch diese elektronischen Übergänge induziert werden. Die Ionisierungsenergien konnten für 1,2,3-Trichlorbenzol, 1,3-Dichlor-2-fluorbenzol, 1-Chlor-2,6-difluorbenzol und 1,3,5-Trichlorbenzol sehr präzise zu 9,2107±0,0007 eV, 9,3288±0,0007 eV, 9,3765±0,0007 eV und 9,3347±0,0012 eV bestimmt werden. Weiterhin wurde für 1,2,3-Trichlorbenzol und 1,3-Dichlor-2-fluorbenzol eine Geometrieänderung während der Anregung und Ionisierung besonders entlang der Schwingungsmode 17b gefunden. Diese Normalmode ist eine Out-of-plane-Schwingung mit starker Beteiligung des an 2-Position substituierten Halogenatoms. Die beiden Moleküle sind folglich im elektronisch angeregten Zustand nicht planar. Das ähnlich substituierte 1-Chlor-2,6-difluorbenzol ist im S1-Zustand planar und ändert seine Geometrie entlang der In-plane-Moden 6a, 9a und 1. 1,3,5-Trichlorbenzol ist ebenfalls planar im elektronisch angeregten Zustand und ändert seine Struktur bei der Ionisierung in Richtung der beiden Normalmoden 6 und 7. Dies ist auf eine symmetriebedingte Jahn-Teller-Verzerrung im ionischen Grundzustand zurückzuführen. Die Jahn-Teller-Aufspaltung konnte aus den erhaltenen MATI-Spektren auf 10cm−1 abgeschätzt werden

Template and Temperature Controlled Polymorph Formation in Squaraine Thin Films

Controlling the polymorph formation in organic semiconductor thin films by the choice of substrate and deposition temperature is a key factor for targeted device performance. Small molecular semiconductors such as the quadrupolar donor-acceptor-donor (D-A-D) type squaraine compounds allow both solution and vapor phase deposition methods. A prototypical anilino squaraine with branched butyl chains as terminal functionalization (SQIB) has been considered for photovoltaic applications due to its broad absorption within the visible to deep-red spectral range. Its opto-electronic properties depend on the formation of the two known polymorphs adopting a monoclinic and orthorhombic crystal phase. Both phases emerge with a strongly preferred out-of-plane and rather random in-plane orientation in spincasted thin films depending on subsequent thermal annealing. Upon vapor deposition on dielectric and conductive substrates, such as silicon dioxide, potassium chloride, graphene and gold, the polymorph expression depends on the choice of growth substrate. In all cases the same pronounced out-of-plane orientation is adopted, but with a surface templated in-plane alignment in case of crystalline substrates. Combining X-ray diffraction, atomic force microscopy, ellipsometry and polarized spectro-microscopy we identify the processing dependent evolution of the crystal phases, correlating morphology and molecular orientations within the textured SQIB films.Comment: 10 pages, 7 figure

Action potentials in primary osteoblasts and in the MG-63 osteoblast-like cell line

Whole-cell patch-clamp analysis revealed a resting membrane potential of −60 mV in primary osteoblasts and in the MG-63 osteoblast-like cells. Depolarization-induced action potentials were characterized by duration of 60 ms, a minimal peak-to-peak distance of 180 ms, a threshold value of −20 mV and a repolarization between the spikes to −45 mV. Expressed channels were characterized by application of voltage pulses between −150 mV and 90 mV in 10 mV steps, from a holding potential of −40 mV. Voltages below −60 mV induced an inward current. Depolarizing voltages above −30 mV evoked two currents: (a) a fast activated and inactivated inward current at voltages between −30 and 30 mV, and (b) a delayed-activated outward current that was induced by voltages above −30 mV. Electrophysiological and pharmacological parameters indicated that hyperpolarization activated strongly rectifying K+ (Kir) channels, whereas depolarization activated tetrodotoxin sensitive voltage gated Na+ (Nav) channels as well as delayed, slowly activated, non-inactivating, and tetraethylammonium sensitive voltage gated K+ (Kv) channels. In addition, RT-PCR showed expression of Nav1.3, Nav1.4, Nav1.5, Nav1.6, Nav1.7, and Kir2.1, Kir2.3, and Kir2.4 as well as Kv2.1. We conclude that osteoblasts express channels that allow firing of action potentials. The final publication is available at Springer via https://doi.org/10.1007/s10863-011-9354-7.BMBF/NANOTOMEDFG/Transregio37Boehringer Ingelheim International GmbHBMBF/NANOTOMEDFG/Transregio/37Boehringer Ingelheim International Gmb

Semi-classical Laguerre polynomials and a third order discrete integrable equation

A semi-discrete Lax pair formed from the differential system and recurrence relation for semi-classical orthogonal polynomials, leads to a discrete integrable equation for a specific semi-classical orthogonal polynomial weight. The main example we use is a semi-classical Laguerre weight to derive a third order difference equation with a corresponding Lax pair.Comment: 11 page

Low-cycle full-field residual strains in cortical bone and their influence on tissue fracture evaluated via in situ stepwise and continuous X-ray computed tomography

As a composite material, the mechanical properties of bone are highly dependent on its hierarchical organisation, thus, macroscopic mechanical properties are dictated by local phenomena, such as microdamage resulting from repetitive cyclic loading of daily activities. Such microdamage is associated with plastic deformation and appears as a gradual accumulation of residual strains. The aim of this study is to investigate local residual strains in cortical bone tissue following compressive cyclic loading, using in situ X-ray computed tomography (XCT) and digital volume correlation (DVC) to provide a deeper insight on the three-dimensional (3D) relationship between residual strain accumulation, cortical bone microstructure and failure patterns. Through a progressive in situ XCT loading–unloading scheme, localisation of local residual strains was observed in highly compressed regions. In addition, a multi-scale in situ XCT cyclic test highlighted the differences on residual strain distribution at the microscale and tissue level, where high strains were observed in regions with the thinnest vascular canals and predicted the failure location following overloading. Finally, through a continuous in situ XCT compression test of cycled specimens, the full-field strain evolution and failure pattern indicated the reduced ability of bone to plastically deform after damage accumulation due to high number of cyclic loads. Altogether, the novel experimental methods employed in this study, combining high-resolution in situ XCT mechanics and DVC, showed a great potential to investigate 3D full-field residual strain development under repetitive loading and its complex interaction with bone microstructure, microdamage and fracture

The role of the cerebellum in social and non-social action sequences : a preliminary LF-rTMS study

An increasing number of studies demonstrated the involvement of the cerebellum in (social) sequence processing. The current preliminary study is the first to investigate the causal involvement of the cerebellum in sequence generation, using low-frequency repetitive transcranial magnetic stimulation (LF-rTMS). By targeting the posterior cerebellum, we hypothesized that the induced neuro-excitability modulation would lead to altered performance on a Picture and Story sequencing task, which involve the generation of the correct chronological order of various social and non-social stories depicted in cartoons or sentences. Our results indicate that participants receiving LF-rTMS over the cerebellum, as compared to sham participants, showed a stronger learning effect from pre to post stimulation for both tasks and for all types of sequences (i.e. mechanical, social scripts, false belief, true belief). No differences between sequence types were observed. Our results suggest a positive effect of LF-rTMS on sequence generation. We conclude that the cerebellum is causally involved in the generation of sequences of social and nonsocial events. Our discussion focuses on recommendations for future studies

Glycosylated hemoglobin as a screening test for hyperglycemia in antipsychotic-treated patients: A follow-up study

Purpose: To assess the point prevalence of undetected prediabetes (preDM) and diabetes mellitus (DM) in patients treated with antipsychotics and to compare metabolic parameters between patients with normoglycemia (NG), preDM, and DM. Furthermore, conversion rates for preDM and DM were determined in a 1-year follow-up.Patients and methods: In a naturalistic cohort of 169 patients, fasting glucose (FG) and hemoglobin A1c (HbA1c) criteria were applied at baseline and at follow-up after 1 year. A distinction was made between baseline patients diagnosed according to FG (B-FG) and those diagnosed according to HbA1c (B-HbA1c). Conversion rates in the 1-year follow-up were compared between B-FG and B-HbA1c.Results: At baseline, preDM and DM were present in 39% and 8%, respectively. As compared to patients with NG, metabolic syndrome was significantly more prevalent in patients with preDM (62% vs 31%). Although the majority of patients were identified by the FG criterion, HbA1c contributed significantly, especially to the number of patients diagnosed with preDM (32%). Regarding the patients with preDM, conversion rates to NG were much higher in the B-FG group than in the B-HbA1c group (72% vs 18%). In patients diagnosed with DM, conversion rates were found for B-FG only.Conclusion: PreDM and DM are highly prevalent in psychiatric patients treated with antipsychotic drugs. HbA1c was shown to be a more stable parameter in identifying psychiatric patients with (an increased risk for) DM, and it should therefore be included in future screening instruments