Constrained β-Hairpins Targeting the EphA4 Ligand Binding Domain.

The activity of the receptor tyrosine kinase EphA4 has been implicated in several pathologies including oncology (gastric and pancreatic cancers) and neurodegenerative diseases (amyotrophic lateral sclerosis and Alzheimer's disease). However, advances in validating EphA4 as a possible drug target have been limited by the lack of suitable pharmacological inhibitors. Recently, we reported on the design of potent EphA4 agonistic agents targeting its ligand binding domain (LBD).

Astrocytic Ephrin-B1 Regulates Oligodendrocyte Development and Myelination.

Astrocytes have been implicated in oligodendrocyte development and myelination, however, the mechanisms by which astrocytes regulate oligodendrocytes remain unclear. Our findings suggest a new mechanism that regulates astrocyte-mediated oligodendrocyte development through ephrin-B1 signaling in astrocytes. Using a mouse model, we examined the role of astrocytic ephrin-B1 signaling in oligodendrocyte development by deleting ephrin-B1 specifically in astrocytes during the postnatal days (P)14-P28 period and used mRNA analysis, immunohistochemistry, and mouse behaviors to study its effects on oligodendrocytes and myelination.

Merocyanines: Electronic Structure and Spectroscopy in Solutions, Solid State, and Gas Phase.

Merocyanines, owing to their readily tunable electronic structure, are arguably the most versatile functional dyes, with ample opportunities for tailored design via variations of both the donor/acceptor (D/A) end groups and π-conjugated polymethine chain. A plethora of spectral properties, such as strong solvatochromism, high polarizability and hyperpolarizabilities, and sensitizing capacity, motivates extensive studies for their applications in light-converting materials for optoelectronics, nonlinear optics, optical storage, fluorescent probes, etc. Evidently, an understanding of the intrinsic structure-property relationships is a prerequisite for the successful design of functional dyes.

EphB2 Signaling Is Implicated in Astrocyte-Mediated Parvalbumin Inhibitory Synapse Development.

Impaired inhibitory synapse development is suggested to drive neuronal hyperactivity in autism spectrum disorders (ASD) and epilepsy. We propose a novel mechanism by which astrocytes control the development of parvalbumin (PV)-specific inhibitory synapses in the hippocampus, implicating ephrin-B/EphB signaling. Here, we utilize genetic approaches to assess functional and structural connectivity between PV and pyramidal cells (PCs) through whole-cell patch-clamp electrophysiology, optogenetics, immunohistochemical analysis, and behaviors in male and female mice.

Tetraanionic Oligo-Dioxaborines: Strongly Absorbing Near-Infrared Dyes.

Polymethine dyes of tetraanionic nature comprising 1,3,2-dioxaborine rings in the polymethine chain and end-groups of different electron-accepting abilities have been synthesized. They can be considered as oligomeric polymethines, where a linear conjugated π-system passes through three 1,3,2-dioxaborine units and a number of tri- and dimethine π-bridges between two end-groups. The obtained dyes exhibit near-infrared absorption and fluorescence, with molar absorption coefficients reaching as high as 564000 M cm in DMF, rendering them among the strongest absorbers known.

Characterization of Solitalea canadensis α-mannosidase with specific activity towards α1,3-Mannosidic linkages.

A recombinant exo-α-mannosidase from Solitalea canadensis (Sc3Man) has been characterized to exhibit strict specificity for hydrolyzing α1,3-mannosidic linkages located at the non-reducing end of glycans containing α-mannose. Enzymatic characterization revealed that Sc3Man operates optimally at a pH of 5.0 and at a temperature of 37 °C.

Design and Photonics of Merocyanine Dyes.

Merocyanines, thanks to their easily adjustable electronic structure, appear to be the most versatile and promising functional dyes. Their D-π-A framework offers ample opportunities for custom design through variations in both donor/acceptor end-groups and the π-conjugated polymethine chain, and leads to a broad range of practical properties, including noticeable solvatochromism, high polarizability/hyperpolarizabilities, and the ability to sensitize various physicochemical processes. Accordingly, merocyanines are applied and extensively studied in various fields, such as light-converting materials for optoelectronics, nonlinear optics, optical storage, solar cells, fluorescent probes, and antitumor agents in photodynamic therapy.

Influence of plasmons on the luminescence properties of solvatochromic merocyanine dyes with different solvatochromism.

The effect of localized surface plasmon resonance (LSPR) of a system consisting of a highly dipolar merocyanine dye and a silver nanoparticle (NP) was studied experimentally and theoretically. A theoretical model for estimating the fluorescence quantum yield () using quantum chemical calculations of intramolecular and intermolecular electronic transition rate constants was developed. Calculations show that the main deactivation channels of the lowest excited singlet state of the studied merocyanines are internal conversion ((S → S)) and fluorescence ((S → S)).

An iPSC-derived astrocyte model of fragile X syndrome exhibits dysregulated cholesterol homeostasis.

Cholesterol is an essential membrane structural component and steroid hormone precursor, and is involved in numerous signaling processes. Astrocytes regulate brain cholesterol homeostasis and they supply cholesterol to the needs of neurons. ATP-binding cassette transporter A1 (ABCA1) is the main cholesterol efflux transporter in astrocytes.

EphA4 targeting agents protect motor neurons from cell death induced by amyotrophic lateral sclerosis -astrocytes.

Amyotrophic lateral sclerosis (ALS) is a degenerative disease that progressively destroys motor neurons (MNs). Earlier studies identified EphA4, a receptor tyrosine kinase, as a possible disease-modifying gene. The complex interplay between the EphA4 receptor and its ephrin ligands in motor neurons and astrocytes has not yet been fully elucidated and includes a putative pro-apoptotic activity of the unbound receptor compared to ephrin-bound receptor.

Functional consequences of postnatal interventions in a mouse model of Fragile X syndrome.

Background: Fragile X syndrome (FXS) is a leading genetic cause of autism and intellectual disability with cortical hyperexcitability and sensory hypersensitivity attributed to loss and hypofunction of inhibitory parvalbumin-expressing (PV) cells. Our studies provide novel insights into the role of excitatory neurons in abnormal development of PV cells during a postnatal period of inhibitory circuit refinement.

Methods: To achieve Fragile X mental retardation gene (Fmr1) deletion and re-expression in excitatory neurons during the postnatal day (P)14-P21 period, we generated Cre/Fmr1 (cOFF) and Cre/Fmr1 (cON) mice, respectively.

NMR-Guided Design of Potent and Selective EphA4 Agonistic Ligands.

In this paper, we applied an innovative nuclear magnetic resonance (NMR)-guided screening and ligand design approach, named focused high-throughput screening by NMR (fHTS by NMR), to derive potent, low-molecular-weight ligands capable of mimicking interactions elicited by ephrin ligands on the receptor tyrosine kinase EphA4. The agents bind with nanomolar affinity, trigger receptor activation in cellular assays with motor neurons, and provide remarkable motor neuron protection from amyotrophic lateral sclerosis (ALS) patient-derived astrocytes. Structural studies on the complex between EphA4 ligand-binding domain and a most active agent provide insights into the mechanism of the agents at a molecular level.

Highly Fluorescent Dianionic Polymethines with a 1,3,2-Dioxaborine Core.

The difluoroboron β-diketonate ring is ever more used for creating bright polymethine-type fluorophores for the visible and NIR range. Here, we report the synthesis and spectral properties of a series of dianionic cyanine dyes of the rare A-π-A-π-A type, with the central dioxaborine ring (A) embedded into the polymethine chain and various electron-acceptor terminal groups A. Depending on the nature of the end group, the maxima of their intensive (with molar extinctions up to 380 000 M cm) and narrow long-wavelength absorption band lie in the range of 530-770 nm.

Surgeon cost feedback through a surgical receipt program reduces cost in sinonasal surgery.

Background: Operating room (OR) costs are a large portion of healthcare expenses. This study evaluates the impact of a surgeon-targeted surgical receipt cost feedback system on OR supply costs in sinonasal surgery and individual components contributing to procedural cost.

Methods: Itemized weekly surgical receipts detailing individual case supply costs were analyzed before and after the implementation of a non-incentivized surgeon cost feedback system between January 2017 and June 2019.

Derivation and Validation of a Diagnostic Prediction Tool for Interstitial Lung Disease.

Background: Interstitial lung disease (ILD) results in high morbidity and health-care utilization. Diagnostic delays remain common and often occur in nonpulmonology settings. Screening for ILD in these settings has the potential to reduce diagnostic delays and improve patient outcomes.

Biochemical characterization of the endo-α-N-acetylgalactosaminidase pool of the human gut symbiont Tyzzerella nexilis.

Three large (2084-, 984-, and 2104-amino acids) endo-α-N-acetylgalactosaminidase candidate genes from the commensal human gut bacterium Tyzzerella nexilis were successfully cloned and subsequently expressed in Escherichia coli. Activity tests of the purified proteins revealed that two of the candidate genes (Tn0153 and Tn2105) were able to hydrolyze the disaccharide unit from Galβ1-3GalNAc-α-pNP. The biochemical characterization revealed optimum pH conditions of 4.

Deeply coloured and highly fluorescent dipolar merocyanines based on tricyanofuran.

Three vinylogous series of merocyanines with the tricyanofuran (TCF) acceptor and different electron-donor groups have been synthesized, and their absorption and fluorescence spectra have been studied in different polarity solvents to reveal the polyene-polymethine transitions of their electronic structures. The TCF dyes with the indole or benzimidazole donor groups have relatively bright fluorescence in the red and near-IR spectral ranges. From the obtained data, the electron-acceptor ability of the TCF group has been estimated to be close to that of the thiobarbituric residue, while the TCF group is less prone to formation of solute-solvent H-bonds in protic media.

Beneficial effects of sound exposure on auditory cortex development in a mouse model of Fragile X Syndrome.

Background: Fragile X syndrome (FXS) is the most common genetic cause of autism and intellectual disability. Fragile X mental retardation gene (Fmr1) knock-out (KO) mice display core deficits of FXS, including abnormally increased sound-evoked responses, and show a delayed development of parvalbumin (PV) cells. Here, we present the surprising result that sound exposure during early development reduces correlates of auditory hypersensitivity in Fmr1 KO mice.

Interaction of Polymethine Dyes with Detonation Nanodiamonds.

Among cationic, anionic, and merocyanine polymethine dyes, the binding to detonation nanodiamond (DND) colloid particles in hydrosol occurs only for negatively charged dye species. This, in view of the positive ζ-potential of the DND used in this study, suggests the predominance of electrostatic interactions over other intermolecular forces in such systems. Indeed, after decorating the merocyanine and the cationic dye by one and two negatively charged sulfopropyl groups, respectively, so that the net charge of their colored species becomes negative, the compounds also demonstrate affinity to the DND particles.

Differences in Complication Rates of Gluteoplasty Procedures That Utilize Autologous Fat Grafting, Implants, or Local Flaps.

Background: Gluteoplasty (gluteal augmentation) procedures are increasing in popularity, but there is not a universally accepted technique to produce optimal outcomes while minimizing risk. In this systematic review, we perform a meta-analysis to evaluate rates of complication from autologous fat grafting, implants, and local flaps, which are the three most common gluteoplasty operations.

Methods: A search of the PubMed/MEDLINE database for articles including the terms "gluteoplasty" OR "gluteal augmentation" OR "buttock augmentation" OR "Brazilian butt lift" OR "gluteal autologous fat graft" OR "buttock autologous fat graft" OR "gluteal implant" OR "buttock implant" OR "gluteal flap" OR "buttock flap" generated 229 articles.

Low-Temperature Effect on the Electronic Structure and Spectral-Fluorescent Properties of Highly Dipolar Merocyanines.

Absorption and fluorescence spectra of a vinylogous series of reversely solvatochromic merocyanines based on benzimidazole and malononitrile have been studied in frozen ethanol solutions at 77 K. It is found that they possess negative thermochromism-in contrast to both positively solvatochromic merocyanines and negatively solvatochromic symmetrical ionic polymethines-and even stronger negative thermofluorochromism. It has been deduced from the spectral data that at low temperature their electronic structure becomes more dipolar, deviating substantially from the virtual ideal polymethine in both the ground and the excited states.

Engineering of an Episomal Plasmid Suitable for High-Throughput Expression in Pichia pastoris.

Aim And Objective: This study describes the design and evaluation of an expression vector for Pichia pastoris (pPICZαBHF), which is based on the commercial vector construct pPICZαB.

Material And Methods: The performance of pPICZαBHF was evaluated with red fluorescent protein as a reporter. Additional His- and Flag-tags on the N-terminal ensured a simplified protein purification procedure.

UV-Vis absorption spectra and electronic structure of merocyanines in the gas phase.

Gas-phase absorption spectra of a merocyanine vinylogous series have been studied for the first time. In vapour, their long-wavelength absorption bands were found to be considerably shifted hypsochromically, broader, more symmetrical, less intense, and their vinylene shift much smaller than even in low-polarity n-hexane. This indicates that in the gas phase their electronic structure closely approaches the nonpolar polyene limiting structure.

Effects of microvirin monomers and oligomers on hepatitis C virus.

Microvirin (MVN) is a carbohydrate-binding protein which shows high specificity for high-mannose type N-glycan structures. In the present study, we tried to identify whether MVN could bind to high-mannose containing hepatitis C virus (HCV) envelope glycoproteins, which are heavily decorated high-mannose glycans. In addition, recombinantly expressed MVN oligomers in di-, tri- and tetrameric form were evaluated for their viral inhibition.