Channelrhodopsin-2 Oligomerization in Cell Membrane Revealed by Photo-Activated Localization Microscopy

Microbial rhodopsins are retinal membrane proteins that found a broad application in optogenetics. The oligomeric state of rhodopsins is important for their functionality and stability. Of particular interest is the oligomeric state in the cellular native membrane environment. Fluorescence microscopy provides powerful tools to determine the oligomeric state of membrane proteins directly in cells. Among these methods is quantitative photoactivated localization microscopy (qPALM) allowing the investigation of molecular organization at the level of single protein clusters. Here, we apply qPALM to investigate the oligomeric state of the first and most used optogenetic tool Channelrhodopsin-2 (ChR2) in the plasma membrane of eukaryotic cells. ChR2 appeared predominantly as a dimer in the cell membrane and did not form higher oligomers. The disulfide bonds between Cys34 and Cys36 of adjacent ChR2 monomers were not required for dimer formation and mutations disrupting these bonds resulted in only partial monomerization of ChR2. The monomeric fraction increased when the total concentration of mutant ChR2 in the membrane was low. The dissociation constant was estimated for this partially monomerized mutant ChR2 as 2.2±0.9 proteins/μm2 . Our findings are important for understanding the mechanistic basis of ChR2 activity as well as for improving existing and developing future optogenetic tools.

Baculovirus Actin Rearrangement-Inducing Factor 1 Can Remodel the Mammalian Actin Cytoskeleton

The actin rearrangement-inducing factor 1 (Arif-1) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an early viral protein that manipulates the actin cytoskeleton of host insect cells. Arif-1 is conserved among alphabaculoviruses and is responsible for the accumulation of F-actin at the plasma membrane during the early phase of infection. However, the molecular mechanism underlying Arif-1-induced cortical actin accumulation is still open. Recent studies have demonstrated the formation of invadosome-like structures induced by Arif-1, suggesting a function in systemic virus spread. Here, we addressed whether Arif-1 is able to manipulate the actin cytoskeleton of mammalian cells comparably to insect cells. Strikingly, transient overexpression of Arif-1 in B16-F1 mouse melanoma cells revealed pronounced F-actin remodeling. Actin assembly was increased, and intense membrane ruffling occurred at the expense of substrate-associated lamellipodia. Deletion mutagenesis studies of Arif-1 confirmed that the C-terminal cytoplasmic region was not sufficient to induce F-actin remodeling, supporting that the transmembrane region for Arif-1 function is also required in mammalian cells. The similarities between Arif-1-induced actin remodeling in insect and mammalian cells indicate that Arif-1 function relies on conserved cellular interaction partners and signal transduction pathways, thus providing an experimental tool to elucidate the underlying mechanism. IMPORTANCE Virus-induced changes of the host cell cytoskeleton play a pivotal role in the pathogenesis of viral infections. The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is known for intervening with the regulation of the host actin cytoskeleton in a wide manner throughout the infection cycle. The actin rearrangement-inducing factor 1 (Arif-1) is a viral protein that causes actin rearrangement during the early phase of AcMNPV infection. Here, we performed overexpression studies of Arif-1 in mammalian cells to establish an experimental tool that allows elucidation of the mechanism underlying the Arif-1-induced remodeling of actin dynamics in a well-characterized and genetically accessible system.

The mitral to aortic/pulmonary velocity-time integral ratio is a simple, feasible and accurate discriminator for echocardiographic evaluation of severe isolated mitral regurgitation

Background

Echocardiographic quantification of mitral regurgitation (MR) remains challenging, requiring dedicated image acquisition, and is limited by potential error from geometric assumptions of annular dimensions. Volume is a product of area and flow and assuming proportional mitral/aortic areas, an increased mitral-inflow volume compared to LV/RV-outflow semi-quantitatively represents greater MR regurgitant volume. Therefore, we investigated the feasibility and diagnostic performance of the mitral-aortic velocity-time integral (VTI) ratio in isolated MR. We also investigated the use of the mitral-pulmonary VTI ratio as an alternative in clinical situations where the LV outflow tract (LVOT) VTI could not be used.

Methods

We reviewed 166 consecutive patients (54 (33% severe MR by multi-parameter integrated expert opinion)). Pulsed-Doppler VTI at the mitral leaflet tips and the left ventricular outflow and continuous-wave Doppler of the right ventricular outflow tract were measured individually and independently by blinded readers (expert and trainee status) to derive the ratio. Receiver operator characteristic area under the curve (AUC) comparison was calculated and compared with effective regurgitant orifice area (EROA >40 mm), regurgitant volume (RVol >6 0mL), vena contracta (VC >0.7 cm), E-velocity >1.2 cm, systolic flow reversal (SFR), left atrial and ventricular dilatation.

Results

Increasing ratio was associated with severe MR (AUC 0.94) with optimal threshold defined at 1.3. This provided significant discrimination for severe MR (AUC 0.81) compared to EROA (0.68), VC (0.52), LV dilatation (0.69), LA dilatation (0.70), SFR (0.73), E-velocity (0.68) all p<0.05, with sensitivity 82% and specificity 94%. The mitral-pulmonary VTI ratio demonstrated similar discrimination (AUC 0.92) with optimal threshold defined at 1.14. Excellent inter-observer reproducibility (intra-class correlation 0.97) was seen between trainee and expert readers. There was no difference in AUC comparison by MR mechanism or patient rhythm.

Conclusions

The mitral-aortic or mitral-pulmonary VTI ratio is a simple, geometric-free parameter feasibly reproducible from routine echocardiographic datasets and is an excellent discriminative tool for severe MR. Readers should consider integration of this parameter in routine reporting.

Funding Acknowledgement

Type of funding sources: None.

The Functional Characterization of GCaMP3.0 Variants Specifically Targeted to Subcellular Domains

Calcium (Ca²⁺) ions play a pivotal role in physiology and cellular signaling. The intracellular Ca²⁺ concentration ([Ca²⁺]_i) is about three orders of magnitude lower than the extracellular concentration, resulting in a steep transmembrane concentration gradient. Thus, the spatial and the temporal dynamics of [Ca²⁺]_i are ideally suited to modulate Ca²⁺-mediated cellular responses to external signals. A variety of highly sophisticated methods have been developed to gain insight into cellular Ca²⁺ dynamics. In addition to electrophysiological measurements and the application of synthetic dyes that change their fluorescent properties upon interaction with Ca²⁺, the introduction and the ongoing development of genetically encoded Ca²⁺ indicators (GECI) opened a new era to study Ca²⁺-driven processes in living cells and organisms. Here, we have focused on one well-established GECI, i.e., GCaMP3.0. We have systematically modified the protein with sequence motifs, allowing localization of the sensor in the nucleus, in the mitochondrial matrix, at the mitochondrial outer membrane, and at the plasma membrane. The individual variants and a cytosolic version of GCaMP3.0 were overexpressed and purified from E. coli cells to study their biophysical properties in solution. All versions were examined to monitor Ca²⁺ signaling in stably transfected cell lines and in primary cortical neurons transduced with recombinant Adeno-associated viruses (rAAV). In this comparative study, we provide evidence for a robust approach to reliably trace Ca²⁺ signals at the (sub)-cellular level with pronounced temporal resolution.

The Landé factors of electrons and holes in lead halide perovskites: universal dependence on the band gap

The Landé or g-factors of charge carriers are decisive for the spin-dependent phenomena in solids and provide also information about the underlying electronic band structure. We present a comprehensive set of experimental data for values and anisotropies of the electron and hole Landé factors in hybrid organic-inorganic (MAPbI₃, MAPb(Br_0.5Cl_0.5)₃, MAPb(Br_0.05Cl_0.95)₃, FAPbBr₃, FA_0.9Cs_0.1PbI_2.8Br_0.2, MA=methylammonium and FA=formamidinium) and all-inorganic (CsPbBr₃) lead halide perovskites, determined by pump-probe Kerr rotation and spin-flip Raman scattering in magnetic fields up to 10 T at cryogenic temperatures. Further, we use first-principles density functional theory (DFT) calculations in combination with tight-binding and k ⋅ p approaches to calculate microscopically the Landé factors. The results demonstrate their universal dependence on the band gap energy across the different perovskite material classes, which can be summarized in a universal semi-phenomenological expression, in good agreement with experiment.

The Landé factors govern all the spin-related basic phenomena and are the key parameters which guide spintronics applications. Here, Kirstein et al. demonstrate a universal dependence of the Landé factors on the bandgap energy of several perovskite materials.

Simultaneous recording of multiple cellular signaling events by frequency- and spectrally-tuned multiplexing of fluorescent probes

Fluorescent probes that change their spectral properties upon binding to small biomolecules, ions, or changes in the membrane potential (Vm) are invaluable tools to study cellular signaling pathways. Here, we introduce a novel technique for simultaneous recording of multiple probes at millisecond time resolution: frequency- and spectrally-tuned multiplexing (FASTM). Different from present multiplexing approaches, FASTM uses phase-sensitive signal detection, which renders various combinations of common probes for Vm and ions accessible for multiplexing. Using kinetic stopped-flow fluorimetry, we show that FASTM allows simultaneous recording of rapid changes in Ca2+, pH, Na+, and Vm with high sensitivity and minimal crosstalk. FASTM is also suited for multiplexing using single-cell microscopy and genetically encoded FRET biosensors. Moreover, FASTM is compatible with optochemical tools to study signaling using light. Finally, we show that the exceptional time resolution of FASTM also allows resolving rapid chemical reactions. Altogether, FASTM opens new opportunities for interrogating cellular signaling.

Neue Terminologie für Sprachentwicklungsstörungen?

Hintergrund

Sprachtherapeutisch-linguistische Fachkreise empfehlen die Anpassung einer von einem internationalen Konsortium empfohlenen Änderung der Nomenklatur für Sprachstörungen im Kindesalter, insbesondere für Sprachentwicklungsstörungen (SES), auch für den deutschsprachigen Raum.

Fragestellung

Ist eine solche Änderung in der Terminologie aus ärztlicher und psychologischer Sicht sinnvoll?

Material und Methode

Kritische Abwägung der Argumente für und gegen eine Nomenklaturänderung aus medizinischer und psychologischer Sicht eines Fachgesellschaften- und Leitliniengremiums.

Ergebnisse

Die ICD-10-GM (Internationale statistische Klassifikation der Krankheiten und verwandter Gesundheitsprobleme, 10. Revision, German Modification) und eine S2k-Leitlinie unterteilen SES in umschriebene SES (USES) und SES assoziiert mit anderen Erkrankungen (Komorbiditäten). Die USES- wie auch die künftige SES-Definition der ICD-11 (International Classification of Diseases 11th Revision) fordern den Ausschluss von Sinnesbehinderungen, neurologischen Erkrankungen und einer bedeutsamen intellektuellen Einschränkung. Diese Definition erscheint weit genug, um leichtere nonverbale Einschränkungen einzuschließen, birgt nicht die Gefahr, Kindern Sprach- und weitere Therapien vorzuenthalten und erkennt das ICD(International Classification of Disease)-Kriterium, nach dem der Sprachentwicklungsstand eines Kindes bedeutsam unter der Altersnorm und unterhalb des seinem Intelligenzalter angemessenen Niveaus liegen soll, an. Die intendierte Ersetzung des Komorbiditäten-Begriffs durch verursachende Faktoren, Risikofaktoren und Begleiterscheinungen könnte die Unterlassung einer dezidierten medizinischen Differenzialdiagnostik bedeuten.

Schlussfolgerungen

Die vorgeschlagene Terminologie birgt die Gefahr, ätiologisch bedeutsame Klassifikationen und differenzialdiagnostische Grenzen zu verwischen und auf wertvolles ärztliches und psychologisches Fachwissen in Diagnostik und Therapie sprachlicher Störungen im Kindesalter zu verzichten.

AAV-Mediated CRISPRi and RNAi Based Gene Silencing in Mouse Hippocampal Neurons

Uncovering the physiological role of individual proteins that are part of the intricate process of cellular signaling is often a complex and challenging task. A straightforward strategy of studying a protein's function is by manipulating the expression rate of its gene. In recent years, the Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9-based technology was established as a powerful gene-editing tool for generating sequence specific changes in proliferating cells. However, obtaining homogeneous populations of transgenic post-mitotic neurons by CRISPR/Cas9 turned out to be challenging. These constraints can be partially overcome by CRISPR interference (CRISPRi), which mediates the inhibition of gene expression by competing with the transcription machinery for promoter binding and, thus, transcription initiation. Notably, CRISPR/Cas is only one of several described approaches for the manipulation of gene expression. Here, we targeted neurons with recombinant Adeno-associated viruses to induce either CRISPRi or RNA interference (RNAi), a well-established method for impairing de novo protein biosynthesis by using cellular regulatory mechanisms that induce the degradation of pre-existing mRNA. We specifically targeted hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels, which are widely expressed in neuronal tissues and play essential physiological roles in maintaining biophysical characteristics in neurons. Both of the strategies reduced the expression levels of three HCN isoforms (HCN1, 2, and 4) with high specificity. Furthermore, detailed analysis revealed that the knock-down of just a single HCN isoform (HCN4) in hippocampal neurons did not affect basic electrical parameters of transduced neurons, whereas substantial changes emerged in HCN-current specific properties.

Observations on early fungal infections with relevance for replant disease in fine roots of the rose rootstock Rosa corymbifera 'Laxa'

Replant disease is a worldwide phenomenon affecting various woody plant genera and species, especially within the Rosaceae. Compared to decades of intensive studies regarding replant disease of apple (ARD), the replant disease of roses (RRD) has hardly been investigated. The etiology of RRD is also still unclear and a remedy desperately needed. In greenhouse pot trials with seedlings of the RRD-sensitive rootstock Rosa corymbifera ‘Laxa’ cultured in replant disease affected soils from two different locations, early RRD symptom development was studied in fine roots. In microscopic analyses we found similarities to ARD symptoms with regards to structural damages, impairment in the root hair status, and necroses and blackening in the cortex tissue. Examinations of both whole mounts and thin sections of fine root segments revealed frequent conspicuous fungal infections in association with the cellular disorders. Particularly striking were fungal intracellular structures with pathogenic characteristics that are described for the first time. Isolated fungi from these tissue areas were identified by means of ITS primers, and many of them were members of the Nectriaceae. In a next step, 35 of these isolates were subjected to a multi-locus sequence analysis and the results revealed that several genera and species were involved in the development of RRD within a single rose plant. Inoculations with selected single isolates (Rugonectria rugulosa and Ilyonectria robusta) in a Perlite assay confirmed their pathogenic relationship to early necrotic host plant reactions, and symptoms were similar to those exhibited in ARD.

Rhizosphere microbial communities associated to rose replant disease: links to plant growth and root metabolites

Growth depression of Rosa plants at sites previously used to cultivate the same or closely related species is a typical symptom of rose replant disease (RRD). Currently, limited information is available on the causes and the etiology of RRD compared to apple replant disease (ARD). Thus, this study aimed at analyzing growth characteristics, root morphology, and root metabolites, as well as microbial communities in the rhizosphere of the susceptible rootstock Rosacorymbifera 'Laxa' grown in RRD-affected soil from two sites (Heidgraben and Sangerhausen), either untreated or disinfected by γ-irradiation. In a greenhouse bioassay, plants developed significantly more biomass in the γ-irradiated than in the untreated soils of both sites. Several plant metabolites detected in R. corymbifera 'Laxa' roots were site- and treatment-dependent. Although aloesin was recorded in significantly higher concentrations in untreated than in γ-irradiated soils from Heidgraben, the concentrations of phenylalanine were significantly lower in roots from untreated soil of both sites. Rhizosphere microbial communities of 8-week-old plants were studied by sequencing of 16S rRNA, ITS, and cox gene fragments amplified from total community DNA. Supported by microscopic observations, sequences affiliated to the bacterial genus Streptomyces and the fungal genus Nectria were identified as potential causal agents of RRD in the soils investigated. The relative abundance of oomycetes belonging to the genus Pythiogeton showed a negative correlation to the growth of the plants. Overall, the RRD symptoms, the effects of soil treatments on the composition of the rhizosphere microbial community revealed striking similarities to findings related to ARD.

Establishing a sensitive fluorescence-based quantification method for cyclic nucleotides

BACKGROUND

Approximately 40% of prescribed drugs exert their activity via GTP-binding protein-coupled receptors (GPCRs). Once activated, these receptors cause transient changes in the concentration of second messengers, e.g., cyclic adenosine 3',5'-monophosphate (cAMP). Specific and efficacious genetically encoded biosensors have been developed to monitor cAMP fluctuations with high spatial and temporal resolution in living cells or tissue. A well characterized biosensor for cAMP is the Förster resonance energy transfer (FRET)-based Epac1-camps protein. Pharmacological characterization of newly developed ligands acting at GPCRs often includes numerical quantification of the second messenger amount that was produced.

RESULTS

To quantify cellular cAMP concentrations, we bacterially over-expressed and purified Epac1-camps and applied the purified protein in a cell-free detection assay for cAMP in a multi-well format. We found that the biosensor can detect as little as 0.15 pmol of cAMP, and that the sensitivity is not impaired by non-physiological salt concentrations or pH values. Notably, the assay tolerated desiccation and storage of the protein without affecting Epac1-camps cyclic nucleotide sensitivity.

CONCLUSIONS

We found that determination cAMP in lysates obtained from cell assays or tissue samples by purified Epac1-camps is a robust, fast, and sensitive assay suitable for routine and high throughput analyses.

Incidence of dementia in the elderly: review of age and sex effects

A review of epidemiological studies about incidence of dementia among the aged is presented. Empirical studies on incidence of dementia have shown considerably differing estimations. Nevertheless, in all studies, an age-related increase in incidence becomes clearly apparent. Epidemiological field-studies could not yield consistent findings concerning the association of incidence and gender. However, most studies found an increased incidence for men until the age of 70–80 years. In older age most studies reported the same incidence for men and women or found an increased incidence of dementia in women. The findings are reviewed and discussed in the context of methodological issues.

Electronic decay of core-excited HCl molecules probed by THz streaking

The ultrafast electronic decay of HCl molecules in the time domain after resonant core excitation was measured. Here, a Cl-2p core electron was promoted to the antibonding σ^* orbital initiating molecular dissociation, and simultaneously, the electronic excitation relaxes via an Auger decay. For HCl, both processes compete on similar ultrashort femtosecond time scales. In order to measure the lifetime of the core hole excitation, we collinearly superimposed 40 fs soft x-ray pulses with intense terahertz (THz) radiation from the free-electron laser in Hamburg (FLASH). Electrons emitted from the molecules are accelerated (streaked) by the THz electric field where the resulting momentum change depends on the field's phase at the instant of ionization. Evaluation of a time-shift between the delay-dependent streaking spectra of photo- and Auger electrons yields a decay constant of (11 ± 2) fs for LMM Auger electrons. For further validation, the method was also applied to the MNN Auger decay of krypton. Reproduction of the value already published in the literature confirms that a temporal resolution much below the duration of the exciting x-ray pulses can be reached.

pH-Lemon, a Fluorescent Protein-Based pH Reporter for Acidic Compartments

Distinct subcellular pH levels, especially in lysosomes and endosomes, are essential for the degradation, modification, sorting, accumulation, and secretion of macromolecules. Here, we engineered a novel genetically encoded pH probe by fusing the pH-stable cyan fluorescent protein (FP) variant, mTurquoise2, to the highly pH-sensitive enhanced yellow fluorescent protein, EYFP. This approach yielded a ratiometric biosensor-referred to as pH-Lemon-optimized for live imaging of distinct pH conditions within acidic cellular compartments. Protonation of pH-Lemon under acidic conditions significantly decreases the yellow fluorescence while the cyan fluorescence increases due to reduced Förster resonance energy transfer (FRET) efficiency. Because of its freely reversible and ratiometric responses, pH-Lemon represents a fluorescent biosensor for pH dynamics. pH-Lemon also shows a sizable pH-dependent fluorescence lifetime change that can be used in fluorescence lifetime imaging microscopy as an alternative observation method for the study of pH in acidic cellular compartments. Fusion of pH-Lemon to the protein microtubule-associated protein 1A/1B-light chain 3B (LC3B), a specific marker of autophagic membranes, resulted in its targeting within autolysosomes of HeLa cells. Moreover, fusion of pH-Lemon to a glycophosphatidylinositol (GPI) anchor allowed us to monitor the entire luminal space of the secretory pathway and the exoplasmic leaflet of the plasma membrane. Utilizing this new pH probe, we revealed neutral and acidic vesicles and substructures inside cells, highlighting compartments of distinct pH throughout the endomembrane system. These data demonstrate, that this novel pH sensor, pH-Lemon, is very suitable for the study of local pH dynamics of subcellular microstructures in living cells.

HCN4 knockdown in dorsal hippocampus promotes anxiety-like behavior in mice

Hyperpolarization‐activated and cyclic nucleotide‐gated (HCN) channels mediate the I_h current in the murine hippocampus. Disruption of the I_h current by knockout of HCN1, HCN2 or tetratricopeptide repeat‐containing Rab8b‐interacting protein has been shown to affect physiological processes such as synaptic integration and maintenance of resting membrane potentials as well as several behaviors in mice, including depressive‐like and anxiety‐like behaviors. However, the potential involvement of the HCN4 isoform in these processes is unknown. Here, we assessed the contribution of the HCN4 isoform to neuronal processing and hippocampus‐based behaviors in mice. We show that HCN4 is expressed in various regions of the hippocampus, with distinct expression patterns that partially overlapped with other HCN isoforms. For behavioral analysis, we specifically modulated HCN4 expression by injecting recombinant adeno‐associated viral (rAAV) vectors mediating expression of short hairpin RNA against hcn4 (shHcn4) into the dorsal hippocampus of mice. HCN4 knockdown produced no effect on contextual fear conditioning or spatial memory. However, a pronounced anxiogenic effect was evident in mice treated with shHcn4 compared to control littermates. Our findings suggest that HCN4 specifically contributes to anxiety‐like behaviors in mice.

Blood glutamate EAAT2-cell grabbing therapy in cerebral ischemia

Background

Excitatory amino acid transporter 2 (EAAT₂) plays a pivotal role in glutamate clearance in the adult brain, thereby preventing excitotoxic effects. Considering the high efficacy of EAAT₂ for glutamate uptake, we hypothesized that the expression of this transporter in mesenchymal stem cells (MSCs) for systemic administration could yield a cell-based glutamate-grabbing therapy, combining the intrinsic properties of these cells with excitotoxic protection.

Methods

To address this hypothesis, EAAT₂-encoding cDNA was introduced into MSCs and human embryonic kidney 293 cells (HEK cells) as the control cell line. EAAT₂ expression and functionality were evaluated by in vitro assays. Blood glutamate-grabbing activity was tested in healthy and ischemic rat models treated with 3 × 10⁶ and 9 × 10⁶ cells/animal.

Findings

The expression of EAAT₂ in both cell types conferred the expected glutamate-grabbing activity in in vitro and in vivo studies. The functional improvement observed in ischemic rats treated with EAAT₂–HEK at low dose, confirmed that this effect was indeed mediated by the glutamate-grabbing activity associated with EAAT₂ functionality. Unexpectedly, both cell doses of non-transfected MSCs induced higher protection than transfected EAAT₂–MSCs by another mechanism independent of the glutamate-grabbing capacity.

Interpretation

Although the transfection procedure most likely interferes with some of the intrinsic protective mechanisms of mesenchymal cells, the results show that the induced expression of EAAT₂ in cells represents a novel alternative to mitigate the excitotoxic effects of glutamate and paves the way to combine this strategy with current cell therapies for cerebral ischemia.

[Decision-making regarding treatment limitation after severe traumatic brain injury: A survey of French neurosurgeons]

BACKGROUND/INTRODUCTION

In France, the law defines and prohibits "unreasonable obstinacy" and provides a framework for the subsequent decision to limit or to cease treatment. It also gives the person the right to appoint a trusted person and to draft advance directives regarding this issue. There have been few studies of neurosurgeons' involvement in decision-making in regard to treatment limitation after severe traumatic brain injury.

AIM OF THE STUDY

The first aim of the study was to assess French neurosurgeons' adherence to the law on patients' rights and end of life which governs such decision-making. The second aim was to assess the prognostic and decision-making criteria applied by neurosurgeons.

METHODS

A declarative practice and opinion survey, using a self-administered questionnaire emailed to all practising neurosurgeons members of the French Society of Neurosurgery, was conducted from April to June 2016.

RESULTS

Of the 197 neurosurgeons contacted, 62 filled in the questionnaire. Discussions regarding treatment limitation were in all cases collegial, as required under the law, and the patient's neurosurgeon was always involved. The trusted person and/or family were always informed and consulted, but their opinions were not consistently taken into account. Advance directives were most often lacking (68%) [56; 80] or inappropriate (27%) [16; 38]. The most frequently used prognostic criteria were clinical parameters, intracranial pressure, cerebral perfusion pressure, and imaging, with significant interindividual variation in their use. The main decision-making criteria were foreseeable disability, expected future quality of life, and age.

CONCLUSIONS

Neurosurgeons showed good compliance with legal requirements, except in the matter of calling for the opinion of an external consultant. Furthermore, this survey confirmed variability in the use of prognosis predictors, and the need for further clinical research so as to achieve more-standardized practices to minimise the subjectivity in decision-making.

Modulation of Hyperpolarization-Activated Inward Current and Thalamic Activity Modes by Different Cyclic Nucleotides

The hyperpolarization-activated inward current, I_h, plays a key role in the generation of rhythmic activities in thalamocortical (TC) relay neurons. Cyclic nucleotides, like 3′,5′-cyclic adenosine monophosphate (cAMP), facilitate voltage-dependent activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels by shifting the activation curve of I_h to more positive values and thereby terminating the rhythmic burst activity. The role of 3′,5′-cyclic guanosine monophosphate (cGMP) in modulation of I_h is not well understood. To determine the possible role of the nitric oxide (NO)-sensitive cGMP-forming guanylyl cyclase 2 (NO-GC2) in controlling the thalamic I_h, the voltage-dependency and cGMP/cAMP-sensitivity of I_h was analyzed in TC neurons of the dorsal part of the lateral geniculate nucleus (dLGN) in wild type (WT) and NO-GC2-deficit (NO-GC2^−/−) mice. Whole cell voltage clamp recordings in brain slices revealed a more hyperpolarized half maximal activation (V_1/2) of I_h in NO-GC2^−/− TC neurons compared to WT. Different concentrations of 8-Br-cAMP/8-Br-cGMP induced dose-dependent positive shifts of V_1/2 in both strains. Treatment of WT slices with lyase enzyme (adenylyl and guanylyl cyclases) inhibitors (SQ22536 and ODQ) resulted in further hyperpolarized V_1/2. Under current clamp conditions NO-GC2^−/− neurons exhibited a reduction in the I_h-dependent voltage sag and reduced action potential firing with hyperpolarizing and depolarizing current steps, respectively. Intrathalamic rhythmic bursting activity in brain slices and in a simplified mathematical model of the thalamic network was reduced in the absence of NO-GC2. In freely behaving NO-GC2^−/− mice, delta and theta band activity was enhanced during active wakefulness (AW) as well as rapid eye movement (REM) sleep in cortical local field potential (LFP) in comparison to WT. These findings indicate that cGMP facilitates I_h activation and contributes to a tonic activity in TC neurons. On the network level basal cGMP production supports fast rhythmic activity in the cortex.

The role of oral anticoagulants in epistaxis

Purpose

The purpose of this retrospective study was to identify the impact of oral anticoagulants on epistaxis with the focus on new oral anticoagulants.

Methods

The study was conducted at the Department  for Ear- Nose- and Throat (ENT), Head and Neck Surgery, Technical University Munich, Germany. All patients presenting in 2014 with the diagnosis of epistaxis to a specialized ENT accident and emergency department were identified and analyzed in clinical data and medication.

Results

600 adult cases, with a median age of 66.6 years were identified with active bleeding. 66.8% of all cases were anticoagulated. Classic oral anticoagulants (COAC) were three times more common in patients than new-generation oral anticoagulants (NOAC). Recurrent bleeding was significantly associated with oral anticoagulants (OAC) (p = 0.014) and bleeding location was most often anterior (p = 0.006). In contrast, severe cases, which required surgery or embolization were significantly more likely in non-anticoagulated middle-aged patients with posterior bleedings (p < 0.05). In our epistaxis cohort, OAC were highly overrepresented (40%) when compared to the general German population (1%) but COAC as well as NOAC played only a minor role in severe courses of epistaxis.

Conclusion

Oral anticoagulation, especially with new-generation drugs, is not associated with more complicated and severe courses of epistaxis, but rather with recurrent bleeding. One should keep this information in mind when triaging the patient in the emergency room and when planning further procedures.

Modulation of thalamocortical oscillations by TRIP8b, an auxiliary subunit for HCN channels

Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels have important functions in controlling neuronal excitability and generating rhythmic oscillatory activity. The role of tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) in regulation of hyperpolarization-activated inward current, I h, in the thalamocortical system and its functional relevance for the physiological thalamocortical oscillations were investigated. A significant decrease in I h current density, in both thalamocortical relay (TC) and cortical pyramidal neurons was found in TRIP8b-deficient mice (TRIP8b-/-). In addition basal cAMP levels in the brain were found to be decreased while the availability of the fast transient A-type K+ current, I A, in TC neurons was increased. These changes were associated with alterations in intrinsic properties and firing patterns of TC neurons, as well as intrathalamic and thalamocortical network oscillations, revealing a significant increase in slow oscillations in the delta frequency range (0.5-4 Hz) during episodes of active-wakefulness. In addition, absence of TRIP8b suppresses the normal desynchronization response of the EEG during the switch from slow-wave sleep to wakefulness. It is concluded that TRIP8b is necessary for the modulation of physiological thalamocortical oscillations due to its direct effect on HCN channel expression in thalamus and cortex and that mechanisms related to reduced cAMP signaling may contribute to the present findings.

Real-life long-term effectiveness of fingolimod in Swiss patients with relapsing-remitting multiple sclerosis

Background and purpose

In 2011, fingolimod was approved in Switzerland for the treatment of relapsing‐remitting multiple sclerosis (RRMS). The aim of the present study was to assess the effectiveness and retention of fingolimod in a real‐life Swiss setting, in which patients can receive fingolimod as both first‐ and second‐line treatment for RRMS.

Methods

This cross‐sectional, observational study with retrospective data collection was performed at 19 sites that comprised both hospitals and office‐based physicians across Switzerland. Sites were asked to document eligible patients in consecutive chronological order to avoid selection bias. Demographic and clinical data from 274 consenting adult patients with RRMS who had received treatment with fingolimod were analyzed.

Results

Mean treatment duration with fingolimod was 32 months. Under fingolimod, 77.7% of patients remained free from relapses and 90.3% did not experience disability progression. The proportion of patients who were free from any clinical disease activity, i.e. without relapses and disability progression, was 72.1%. A total of 28.5% of patients had been RRMS treatment‐naïve prior to fingolimod therapy. High long‐term treatment retention rates ranging between 95.7% at 24 months and 87.8% at 36 months were observed.

Conclusion

In this Swiss cohort of naïve and pre‐treated subjects with RRMS, the majority of patients under fingolimod treatment showed freedom from relapses and disability progression. In addition, treatment retention rate over 2 and 3 years was high, irrespective of previous treatment.

Outcomes of Ulnar Shortening for Ulnar Impaction Syndrome Using the 2.7 mm AO Ulna Shortening Osteotomy System

Background: Ulnar shortening osteotomy is a well-established treatment for ulnar impaction syndrome. Controversy remains regarding the most effective system to achieve efficient bony union, whilst minimising incidence of complications, particularly hardware irritation. We present outcomes at 2 years using the recently released low profile AO osteotomy system.

Methods: 32 consecutive patients with significant pain from ulnar impaction syndrome (idiopathic or post-traumatic), without degenerative changes of the distal radio-ulnar joint, were included. Time to union, range of motion, grip strength, pain and complications were recorded.

Results: Median time to union was 10.14 weeks (9.27–11.01, 95%CI), with one nonunion. Visual Analogue Pain score, grip strength and range of motion improved significantly. No patient experienced hardware irritation. No plate required removal. Positive ulnar variance was reduced by 3.8 mm (mean).

Conclusions: The low profile AO system appears effective in achieving bony union whilst minimising incidence of hardware irritation, at a follow up of 2 years

Thermodynamic description of Tc(iv) solubility and carbonate complexation in alkaline NaHCO3–Na2CO3–NaCl systems

A comprehensive thermodynamic model is derived for the system Tc⁴⁺–Na⁺–Cl⁻–OH⁻–HCO₃⁻–CO₃²⁻–H₂O(l) based upon solubility experiments in alkaline carbonate solutions, advanced spectroscopic techniques and DFT calculations.

International registry on the use of the CytoSorb® adsorber in ICU patients : Study protocol and preliminary results

INTRODUCTION

The aim of this clinical registry is to record the use of CytoSorb® adsorber device in critically ill patients under real-life conditions.

METHODS

The registry records all relevant information in the course of product use, e. g., diagnosis, comorbidities, course of the condition, treatment, concomitant medication, clinical laboratory parameters, and outcome (ClinicalTrials.gov Identifier: NCT02312024). Primary endpoint is in-hospital mortality as compared to the mortality predicted by the APACHE II and SAPS II score, respectively.

RESULTS

As of January 30, 2017, 130 centers from 22 countries were participating. Data available from the start of the registry on May 18, 2015 to November 24, 2016 (122 centers; 22 countries) were analyzed, of whom 20 centers from four countries provided data for a total of 198 patients (mean age 60.3 ± 15.1 years, 135 men [68.2%]). In all, 192 (97.0%) had 1 to 5 Cytosorb® adsorber applications. Sepsis was the most common indication for CytoSorb® treatment (135 patients). Mean APACHE II score in this group was 33.1 ± 8.4 [range 15-52] with a predicted risk of death of 78%, whereas the observed mortality was 65%. There were no significant decreases in the SOFA scores after treatment (17.2 ± 4.8 [3-24]). However interleukin-6 levels were markedly reduced after treatment (median 5000 pg/ml before and 289 pg/ml after treatment, respectively).

CONCLUSIONS

This third interim report demonstrates the feasibility of the registry with excellent data quality and completeness from 20 study centers. The results must be interpreted with caution, since the numbers are still small; however the disease severity is remarkably high and suggests that adsorber treatment might be used as an ultimate treatment in life-threatening situations. There were no device-associated side effects.

Dm5-HT2B: Pharmacological Characterization of the Fifth Serotonin Receptor Subtype of Drosophila melanogaster

Serotonin (5-hydroxytryptamine, 5-HT) is an important regulator of physiological and behavioral processes in both protostomes (e.g., insects) and deuterostomes (e.g., mammals). In insects, serotonin has been found to modulate the heart rate and to control secretory processes, development, circadian rhythms, aggressive behavior, as well as to contribute to learning and memory. Serotonin exerts its activity by binding to and activating specific membrane receptors. The clear majority of these receptors belong to the superfamily of G-protein-coupled receptors. In Drosophila melanogaster, a total of five genes have been identified coding for 5-HT receptors. From this family of proteins, four have been pharmacologically examined in greater detail, so far. While Dm5-HT_1A, Dm5-HT_1B, and Dm5-HT₇ couple to cAMP signaling cascades, the Dm5-HT_2A receptor leads to Ca²⁺ signaling in an inositol-1,4,5-trisphosphate-dependent manner. Based on sequence similarity to homologous genes in other insects, a fifth D. melanogaster gene was uncovered coding for a Dm5-HT_2B receptor. Knowledge about this receptor’s pharmacological properties is very limited. This is quite surprising because Dm5-HT_2B has been attributed to distinct physiological functions based on genetic interference with its gene expression. Mutations were described reducing the response of the larval heart to 5-HT, and specific knockdown of Dm5-HT_2B mRNA in hemocytes resulted in a higher susceptibility of the flies to bacterial infection. To gain deeper understanding of Dm5-HT_2B’s pharmacology, we evaluated the receptor’s response to a series of established 5-HT receptor agonists and antagonists in a functional cell-based assay. Metoclopramide and mianserin were identified as two potent antagonists that may allow pharmacological interference with Dm5-HT_2B signaling in vitro and in vivo.

Functional disorders of swallowing

Swallowing involves complex coordination of the neuromuscular anatomy and physiology of the oropharynx and esophagus, controlled by the enteric and central nervous systems. Dysphagia is classified as either oropharyngeal or esophageal and results from mechanical or structural disturbances. Videofluoroscopy, fiberoptic endoscopic evaluation of swallowing, barium swallow, manometry, and endoscopy are common modalities utilized in diagnosis, but none is as important as a patient's history. Functional dysphagia is a diagnosis of exclusion and is based on Rome criteria. Its mechanism is unknown but potentially related to visceral hypersensitivity, inappropriate pain perception, or unidentified contraction abnormalities. Its management is mainly supportive; however, there is literature to suggest, but not confirm, benefit with the use of antidepressants. Continued understanding of functional dysphagia and other functional esophageal disorders, including globus sensation, will require further investigation into diagnostic algorithms and finding treatment methods.

Caspase-3 and GFAP as early markers for apoptosis and astrogliosis in shRNA-induced hippocampal cytotoxicity

Genetic manipulation of cells and tissue by RNA interference has significantly contributed to the functional characterization of individual proteins and their role in physiological processes. Despite its versatility, RNA interference can have detrimental side effects, including reduced cell viability. We applied recombinant adeno-associated viruses by stereotaxic injection into the murine hippocampus to express different short hairpin RNA (shRNA) constructs along with eGFP. Tissue responses were assessed immunohistochemically for up to 8 weeks post-infection. Strong hippocampal degeneration and tissue atrophy was observed, most likely induced by high shRNA expression. The effect was entirely absent in mice injected with vectors driving only expression of eGFP. Active caspase-3 (Casp-3) and glial fibrillary acidic protein (GFAP) were identified as molecular markers and early indicators of adverse tissue responses. Our findings also demonstrate that detrimental effects of high shRNA expression in hippocampal tissue can be monitored even before the onset of tissue degeneration.

Solubility and hydrolysis of Tc(iv) in dilute to concentrated KCl solutions: an extended thermodynamic model for Tc4+–H+–K+–Na+–Mg2+–Ca2+–OH−–Cl−–H2O(l) mixed systems

The solubility of Tc(iv) under strongly reducing conditions is investigated in KCl solutions with 1.5 ≤ pHm ≤ 14.5, and an extended thermodynamic model for the system Tc⁴⁺–H⁺–K⁺–Na⁺–Mg²⁺–Ca²⁺–OH⁻–Cl⁻–H₂O(l) is provided.

AmTAR2: Functional characterization of a honeybee tyramine receptor stimulating adenylyl cyclase activity

The biogenic monoamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. Insects such as honeybees do not synthesize these neuroactive substances. Instead, they employ octopamine and tyramine for comparable physiological functions. These biogenic amines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Based on pharmacological data obtained on heterologously expressed receptors, α- and β-adrenergic-like octopamine receptors are better activated by octopamine than by tyramine. Conversely, GPCRs forming the type 1 tyramine receptor clade (synonymous to octopamine/tyramine receptors) are better activated by tyramine than by octopamine. More recently, receptors were characterized which are almost exclusively activated by tyramine, thus forming an independent type 2 tyramine receptor clade. Functionally, type 1 tyramine receptors inhibit adenylyl cyclase activity, leading to a decrease in intracellular cAMP concentration ([cAMP]_i). Type 2 tyramine receptors can mediate Ca²⁺ signals or both Ca²⁺ signals and effects on [cAMP]_i. We here provide evidence that the honeybee tyramine receptor 2 (AmTAR2), when heterologously expressed in flpTM cells, exclusively causes an increase in [cAMP]_i. The receptor displays a pronounced preference for tyramine over octopamine. Its activity can be blocked by a series of established antagonists, of which mianserin and yohimbine are most efficient. The functional characterization of two tyramine receptors from the honeybee, AmTAR1 (previously named AmTYR1) and AmTAR2, which respond to tyramine by changing cAMP levels in opposite direction, is an important step towards understanding the actions of tyramine in honeybee behavior and physiology, particularly in comparison to the effects of octopamine.

Elimination of a ligand gating site generates a supersensitive olfactory receptor

Olfaction poses one of the most complex ligand-receptor matching problems in biology due to the unparalleled multitude of odor molecules facing a large number of cognate olfactory receptors. We have recently deorphanized an olfactory receptor, TAAR13c, as a specific receptor for the death-associated odor cadaverine. Here we have modeled the cadaverine/TAAR13c interaction, exchanged predicted binding residues by site-directed mutagenesis, and measured the activity of the mutant receptors. Unexpectedly we observed a binding site for cadaverine at the external surface of the receptor, in addition to an internal binding site, whose mutation resulted in complete loss of activity. In stark contrast, elimination of the external binding site generated supersensitive receptors. Modeling suggests this site to act as a gate, limiting access of the ligand to the internal binding site and thereby downregulating the affinity of the native receptor. This constitutes a novel mechanism to fine-tune physiological sensitivity to socially relevant odors.

Expression and characterization of a recombinant i-type lysozyme from the harlequin ladybird beetle Harmonia axyridis

Lysozymes are enzymes that destroy bacterial cell walls by hydrolysing the polysaccharide component of peptidoglycan. In insects, there are two classes of lysozymes, the c-type with muramidase activity and the i-type whose prototypical members from annelids and molluscs possess both muramidase and isopeptidase activities. Many insect genes encoding c-type and i-type lysozymes have been identified during genome and transcriptome analyses, but only c-type lysozymes have been functionally characterized at the protein level. Here we produced one of five i-type lysozymes represented in the immunity-related transcriptome of the invasive harlequin ladybird beetle Harmonia axyridis as recombinant protein. This was the only one containing the serine and histidine residues that are thought to be required for isopeptidase activity. This i-type lysozyme was recombinantly expressed in the yeast Pichia pastoris, but the purified protein was inactive in both muramidase and isopeptidase assays. Transcription and immunofluorescence analysis revealed that this i-type lysozyme is produced in the fat body but is not inducible by immune challenge. These data suggest that i-type lysozymes in insects may have acquired novel and as yet undetermined functions in the course of evolution.