Implementation of N-Interval fourier transform analysis - Application to compound action potentials

N -Interval Fourier Transform Analysis (N -FTA) allows for spectral separation of a periodic target signal from uncorrelated background interference. A N -FTA pseudo-code is presented. The spectral resolution is defined by the repetition rate of the near periodic signal. Acceptance criteria for spectral targets were defined such that the probability of accepting false positives is less than 1 500 . Simulated and recorded neural compound action potentials (CAPs) were investigated. Simulated data allowed for comparison with reference solutions demonstrating the stability of N -FTA at conditions being comparable to real world data. Background activity was assessed with small errors. Evoked target components were assessed down to power spectral density being approximately N times below the background level. Validation was completed investigating a measured CAP. In neurophysiological recordings, this approach allows for accurate separation of near periodic evoked activity from uncorrelated background activities for frequencies below 1kHz.•N-FTA allows for spectral separation of a periodic target signal from uncorrelated interference by analyzing a segment containing N target signal repetitions.•A MATLAB implementation of the algorithm is provided along with simulated and recorded data.•N-FTA was successfully validated using simulated and measured data for CAPs.

Nuclear Import and Export of YAP and TAZ

Yes-associated Protein (YAP) and its paralog Transcriptional Coactivator with PDZ-binding Motif (TAZ) are major regulators of gene transcription/expression, primarily controlled by the Hippo pathway and the cytoskeleton. Integrating an array of chemical and mechanical signals, they impact growth, differentiation, and regeneration. Accordingly, they also play key roles in tumorigenesis and metastasis formation. Their activity is primarily regulated by their localization, that is, Hippo pathway- and/or cytoskeleton-controlled cytosolic or nuclear sequestration. While many details of such prevailing retention models have been elucidated, much less is known about their actual nuclear traffic: import and export. Although their size is not far from the cutoff for passive diffusion through the nuclear pore complex (NPC), and they do not contain any classic nuclear localization (NLS) or nuclear export signal (NES), evidence has been accumulating that their shuttling involves mediated and thus regulatable/targetable processes. The aim of this review is to summarize emerging information/concepts about their nucleocytoplasmic shuttling, encompassing the relevant structural requirements (NLS, NES), nuclear transport receptors (NTRs, karyophererins), and NPC components, along with the potential transport mechanisms and their regulation. While dissecting retention vs. transport is often challenging, the emerging picture suggests that YAP/TAZ shuttles across the NPC via multiple, non-exclusive, mediated mechanisms, constituting a novel and intriguing facet of YAP/TAZ biology.

Myocardin-related transcription factor and serum response factor regulate cilium turnover by both transcriptional and local mechanisms

Turnover of the primary cilium (PC) is critical for proliferation and tissue homeostasis. Each key component of the PC resorption machinery, the HEF1/Aurora kinase A (AurA)/HDAC6 pathway harbors cis-elements potentially targeted by the transcriptional co-activator myocardin-related transcription factor (MRTF) and/or its partner serum response factor (SRF). Thus we investigated if MRTF and/or SRF regulate PC turnover. Here we show that (1) both MRTF and SRF are indispensable for serum-induced PC resorption, and (2) they act via both transcriptional and local mechanisms. Intriguingly, MRTF and SRF are present in the basal body and/or the PC, and serum facilitates ciliary MRTF recruitment. MRTF promotes the stability and ciliary accumulation of AurA and facilitates SRF phosphorylation. Ciliary SRF interacts with AurA and HDAC6. MRTF also inhibits ciliogenesis. It interacts with and is required for the correct localization of the ciliogenesis modulator CEP290. Thus, MRTF and SRF are critical regulators of PC assembly and/or disassembly, acting both as transcription factors and as PC constituents.

P1790TAVI is associated with less patient-prosthesis-mismatch than surgical aortic valve repair of severe aortic stenosis: A systematic review and meta-analysis

Background

TAVI has shown to be non-inferior to surgical aortic valve replacement (sAVR) in terms of mortality for the treatment of intermediate and high-risk patients with severe aortic stenosis (AS).

Purpose

We sought to assess whether there is a difference on echocardiographic parameters up to 2 years after TAVI and sAVR

Methods

We conducted a systematic review and a random-effect model meta-analysis of randomized controlled trials that compared TAVI and sAVR. The primary outcome was post-proceduralpatient-prosthesis-mismatch (PPM). Secondary outcomes were post-procedural and 2-year effective orifice area (EOA), paravalvular gradient (PVG) and moderate/severe paravalvular leak (PVL).

Results

We identified 5 trials with a total of 5552 participants with AS, including 2777 patients randomized to TAVI and 2775 randomized to sAVR (Figure 1). TAVI was associated with a significant 35% relative risk reduction (95% CI [0.50–0.8), p=0.005) in moderate/severe post-procedural PPM. The effect was more evident in self- than balloon-expandable valves (p=0.029). Similar results were found in terms of post procedural EOA (RR=0.53, 95% CI [0.43–0.62]), and residual gradients (RR=0.54, 95% CI [0.32–0.76]). As expected, TAVI demonstrated higher rates of moderate/severe PVL (RR=9.41, 95% CI [5.22–16.96]). The results were sustainable at 2 years as seen in pooled increased EOA (pooled mean difference 0.48, 95% CI [0.24–0.72]), and the pooled decreased residual gradients of 0.58 (95% CI [0.77–0.25]) in favor of TAVI. The incidence of moderate/severe PVL remained also lower in sAVR patients (RR=10.39, 95% CI [4.80–22.46]).

Figure 1. PRISMA flow diagram

Conclusions

Our meta-analysis suggests that TAVI is associated with a lower risk of PPM, as well as higher EOA and lower residual gradients through 2 years of follow-up. This was accompanied by a higher incidence of moderate/severe PVL compared to sAVR. Future research should focus on the effect of these echocardiographic differences on clinical outcomes.

P1676De novo aortic insufficiency following long term LVAD support can be successfully treated with TAVI and a pre-stenting technique

Background/Introduction

Long-term continuous flow left ventricular assist device (cf-LVAD) can result in the development of relevant aortic regurgitation (AR). Although its impact on survival is still controversial, it causes heart failure related symptoms. Current evidence for less invasive strategies to treat AR in cf-LVAD patients is limited.

Purpose

This study sought to investigate the value of transcatheter aortic valve implantation (TAVI) to treat severe de novo AR in patients on long-term cf-LVAD support. Methods

We performed a retrospective analysis of 13 patients with severe AR following cf-LVAD implantation treated with TAVI between 2010 and 2019. TAVI's were performed via transfemoral (n=11), transapical (n=1) and transaxillary (n=1) access route. CoreValve (n=2), LotusValve (n=1), SapienXT (n=1) and Sapien3 (n=9) were used as transcatheter heart valves. In 4 patients, a new off-label strategy using landing-zone pre-stenting with a Sinus-XL stent was used (Figure 1).

Results

The median time interval from LVAD-implantation to TAVI was 1.7 years [interquartile range (IQR): 1.0 - 3.1]. Median age was 62 years [IQR: 57 - 67]. No procedural mortality or stroke was observed. Overall, device success according to VARC-II criteria was low due to a high rate of second valve necessity (54%). In contrast to the standard implantation technique, device success was 100% when the newly developed pre-stenting technique was applied (Table 1). Aortic regurgitation at discharge was none/trace in all patients. Valve function remained stable in all patients during a median echocardiographic follow-up time of 105 days [IQR: 11 - 298].

Table 1 Overall Sinus-XL prestenting (n=4) NO prestenting (n=9) Device success 7 (54) 4 (100) 3 (33) Procedural mortality 0 (0) 0 (0) 0 (0) Correct positioning of a single valve 7 (54) 4 (100) 3 (33) Intended valve performance 13 (100) 4 (100) 9 (100) Moderate or severe aortic regurgitation 0 (0) 0 (0) 0 (0)

Figure 1

Conclusions

Transcatheter aortic valve implantation is an efficient tool to treat cf-LVAD induced severe AR. The challenging anatomy of the non-calcified device landing zone causes a relatively high rate of primary device failure, which could be overcome with a pre-stenting technique.

Acknowledgement/Funding

None

Influence of posture on blink reflex prepulse inhibition induced by somatosensory inputs from upper and lower limbs

BACKGROUND

Prepulse inhibition (PPI) is a neurophysiological phenomenon whereby a weak stimulus modulates the reflex response to a subsequent strong stimulus. Its physiological purpose is to avoid interruption of sensory processing by subsequent disturbing stimuli at the subcortical level, thereby preventing undesired motor reactions. An important hub in the PPI circuit is the pedunculopontine nucleus, which is also involved in the control of posture and sleep/wakefulness.

OBJECTIVE

To study the effect of posture (supine versus standing) on PPI, induced by somatosensory prepulses to either upper or lower limb. PPI was measured as the percentage inhibition of the blink reflex response to electrical supraorbital nerve (SON) stimulation.

METHODS

Sixteen healthy volunteers underwent bilateral blink reflex recordings following SON stimulation either alone (baseline) or preceded by an electrical prepulse to the median nerve (MN) or sural nerve (SN), both in supine and standing. Stimulus intensity was 8 times sensory threshold for SON, and 2 times sensory threshold for MN and SN, respectively. Eight stimuli were applied in each condition.

RESULTS

Baseline blink reflex parameters did not differ significantly between the two postures. Prepulse stimulation to MN and SN caused significant inhibition of R2. In supine but not in standing, R2 was significantly more inhibited by MN than by SN prepulses. In standing, SN stimulation caused significantly more inhibition of R2 than in supine, while the inhibition caused by MN prepulses did not differ significantly between postures.

SIGNIFICANCE

PPI induced by lower limb afferent input may contribute to postural control while standing.

Focus on the pedunculopontine nucleus. Consensus review from the May 2018 brainstem society meeting in Washington, DC, USA

The pedunculopontine nucleus (PPN) is located in the mesopontine tegmentum and is best delimited by a group of large cholinergic neurons adjacent to the decussation of the superior cerebellar peduncle. This part of the brain, populated by many other neuronal groups, is a crossroads for many important functions. Good evidence relates the PPN to control of reflex reactions, sleep-wake cycles, posture and gait. However, the precise role of the PPN in all these functions has been controversial and there still are uncertainties in the functional anatomy and physiology of the nucleus. It is difficult to grasp the extent of the influence of the PPN, not only because of its varied functions and projections, but also because of the controversies arising from them. One controversy is its relationship to the mesencephalic locomotor region (MLR). In this regard, the PPN has become a new target for deep brain stimulation (DBS) for the treatment of parkinsonian gait disorders, including freezing of gait. This review is intended to indicate what is currently known, shed some light on the controversies that have arisen, and to provide a framework for future research.

Acyclovir resistance in herpes simplex virus type I encephalitis: a case report

Acyclovir resistance is rarely seen in herpes simplex virus (HSV) type I encephalitis. Prevalence rates vary between 0.5 % in immunocompetent patients (Christophers et al. 1998; Fife et al. 1994) and 3.5–10 % in immunocompromised patients (Stranska et al. 2005). We report a 45-year-old, immunocompetent (negative HIV antigen/antibody testing), female patient, without previous illness who developed—after a febrile prodromal stage—aphasia and psychomotor slowing. Cerebral magnetic resonance imaging (cMRI) showed right temporal and insular T2-hyperintense lesions with spreading to the contralateral temporal lobe. Cerebrospinal fluid (CSF) analysis yielded lymphocytic pleocytosis and elevated protein level. Polymerase chain reaction testing for HSV type I showed a positive result in repeat lumbar puncture. HSV type I encephalitis was diagnosed and intravenous acyclovir treatment was initiated (750 mg t.i.d.). Acyclovir treatment was intensified to 1000 mg t.i.d., due to clinical deterioration, ongoing pleocytosis and progression on cMRI 5 days after initiation of antiviral therapy. In parallel, acyclovir resistance testing showed mutation of thymidine kinase gene at position A156V prompting foscarnet therapy (60 mg t.i.d.). Patient’s condition improved dramatically over 2 weeks. Acyclovir resistance is rare but should be considered in case of clinical worsening of patient’s condition. To our knowledge, this is the first report of acyclovir resistance in HSV type I encephalitis of an immunocompetent and previously healthy patient in Austria.

Context-dependent switch in chemo/mechanotransduction via multilevel crosstalk among cytoskeleton-regulated MRTF and TAZ and TGFβ-regulated Smad3

Myocardin-related transcription factor (MRTF) and TAZ are major mechanosensitive transcriptional co-activators that link cytoskeleton organization to gene expression. Despite many similarities in their regulation, their physical and/or functional interactions are unknown. Here we show that MRTF and TAZ associate partly through a WW domain-dependent mechanism, and exhibit multilevel crosstalk affecting each other's expression, transport and transcriptional activity. Specifically, MRTF is essential for TAZ expression; TAZ and MRTF inhibit each other's cytosolic mobility and stimulus-induced nuclear accumulation; they antagonize each other's stimulatory effect on the α-smooth muscle actin (SMA) promoter, which harbours nearby cis-elements for both, but synergize on isolated TEAD-elements. Importantly, TAZ confers Smad3 sensitivity to the SMA promoter. Thus, TAZ is a context-dependent switch during mechanical versus mechano/chemical signalling, which inhibits stretch-induced but is indispensable for stretch+TGFβ-induced SMA expression. Crosstalk between these cytoskeleton-regulated factors seems critical for fine-tuning mechanical and mechanochemical transcriptional programmes underlying myofibroblast transition, wound healing and fibrogenesis.

Twisted amide electrophiles enable cyclic peptide sequencing

There is an ever-increasing interest in synthetic methods that not only enable peptide macrocyclization, but also facilitate downstream application of the synthesized molecules. We have found that aziridine amides are stereoelectronically attenuated in a macrocyclic environment such that non-specific interactions with biological nucleophiles are reduced or even shut down. The electrophilic reactivity, revealed at high pH, enables peptide sequencing by mass spectrometry, which will further broaden the utility of aziridine amide-containing libraries of macrocycles.

Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study

BACKGROUND AND OBJECTIVES

Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment.

METHODS

Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group.

RESULT

In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time.

CONCLUSION

Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen.