Timing and precision of rattlesnake spinal motoneurons are determined by the KV72/3 potassium channel

The evolution of novel motor behaviors requires modifications in the central pattern generators (CPGs) controlling muscle activity. How such changes gradually lead to novel behaviors remains enigmatic due to the long time course of evolution. Rattlesnakes provide a unique opportunity to investigate how a locomotor CPG was evolutionarily modified to generate a novel behavior-in this case, acoustic signaling. We show that motoneurons (MNs) in the body and tail spinal cord of rattlesnakes possess fundamentally different physiological characteristics, which allow MNs in the tail to integrate and transmit CPG output for controlling superfast muscles with high temporal precision. Using patch-clamp electrophysiology, we demonstrate that these differences in locomotor and rattle MNs are mainly determined by KV72/3 potassium channels. However, although KV72/3 exerted a significantly different influence on locomotor and rattle MN physiology, single-cell RNA-seq unexpectedly did not reveal any differences in KV72/3 channels' expression. VIDEO ABSTRACT.

Direct proteomic and high-resolution microscopy biopsy analysis identifies distinct ventricular fates in severe aortic stenosis

The incidence of aortic valve stenosis (AS), the most common reason for aortic valve replacement (AVR), increases with population ageing. While untreated AS is associated with high mortality, different hemodynamic subtypes range from normal left-ventricular function to severe heart failure. However, the molecular nature underlying four different AS subclasses, suggesting vastly different myocardial fates, is unknown. Here, we used direct proteomic analysis of small left-ventricular biopsies to identify unique protein expression profiles and subtype-specific AS mechanisms. Left-ventricular endomyocardial biopsies were harvested from patients during transcatheter AVR, and inclusion criteria were based on echocardiographic diagnosis of severe AS and guideline-defined AS-subtype classification: 1) normal ejection fraction (EF)/high-gradient; 2) low EF/high-gradient; 3) low EF/low-gradient; and 4) paradoxical low-flow/low-gradient AS. Samples from non-failing donor hearts served as control. We analyzed 25 individual left-ventricular biopsies by data-independent acquisition mass spectrometry (DIA-MS), and 26 biopsies by histomorphology and cardiomyocytes by STimulated Emission Depletion (STED) superresolution microscopy. Notably, DIA-MS reliably detected 2273 proteins throughout each individual left-ventricular biopsy, of which 160 proteins showed significant abundance changes between AS-subtype and non-failing samples including the cardiac ryanodine receptor (RyR2). Hierarchical clustering segregated unique proteotypes that identified three hemodynamic AS-subtypes. Additionally, distinct proteotypes were linked with AS-subtype specific differences in cardiomyocyte hypertrophy. Furthermore, superresolution microscopy of immunolabeled biopsy sections showed subcellular RyR2-cluster fragmentation and disruption of the functionally important association with transverse tubules, which occurred specifically in patients with systolic dysfunction and may hence contribute to depressed left-ventricular function in AS.

Calpain cleavage of Junctophilin-2 generates a spectrum of calcium-dependent cleavage products and DNA-rich NT1-fragment domains in cardiomyocytes

Calpains are calcium-activated neutral proteases involved in the regulation of key signaling pathways. Junctophilin-2 (JP2) is a Calpain-specific proteolytic target and essential structural protein inside Ca²⁺ release units required for excitation-contraction coupling in cardiomyocytes. While downregulation of JP2 by Calpain cleavage in heart failure has been reported, the precise molecular identity of the Calpain cleavage sites and the (patho-)physiological roles of the JP2 proteolytic products remain controversial. We systematically analyzed the JP2 cleavage fragments as function of Calpain-1 versus Calpain-2 proteolytic activities, revealing that both Calpain isoforms preferentially cleave mouse JP2 at R565, but subsequently at three additional secondary Calpain cleavage sites. Moreover, we identified the Calpain-specific primary cleavage products for the first time in human iPSC-derived cardiomyocytes. Knockout of RyR2 in hiPSC-cardiomyocytes destabilized JP2 resulting in an increase of the Calpain-specific cleavage fragments. The primary N-terminal cleavage product NT₁ accumulated in the nucleus of mouse and human cardiomyocytes in a Ca²⁺-dependent manner, closely associated with euchromatic chromosomal regions, where NT₁ is proposed to function as a cardio-protective transcriptional regulator in heart failure. Taken together, our data suggest that stabilizing NT₁ by preventing secondary cleavage events by Calpain and other proteases could be an important therapeutic target for future studies.

A junctional cAMP compartment regulates rapid Ca2+ signaling in atrial myocytes

Axial tubule junctions with the sarcoplasmic reticulum control the rapid intracellular Ca²⁺-induced Ca²⁺ release that initiates atrial contraction. In atrial myocytes we previously identified a constitutively increased ryanodine receptor (RyR2) phosphorylation at junctional Ca²⁺ release sites, whereas non-junctional RyR2 clusters were phosphorylated acutely following β-adrenergic stimulation. Here, we hypothesized that the baseline synthesis of 3',5'-cyclic adenosine monophosphate (cAMP) is constitutively augmented in the axial tubule junctional compartments of atrial myocytes. Confocal immunofluorescence imaging of atrial myocytes revealed that junctin, binding to RyR2 in the sarcoplasmic reticulum, was densely clustered at axial tubule junctions. Interestingly, a new transgenic junctin-targeted FRET cAMP biosensor was exclusively co-clustered in the junctional compartment, and hence allowed to monitor cAMP selectively in the vicinity of junctional RyR2 channels. To dissect local cAMP levels at axial tubule junctions versus subsurface Ca²⁺ release sites, we developed a confocal FRET imaging technique for living atrial myocytes. A constitutively high adenylyl cyclase activity sustained increased local cAMP levels at axial tubule junctions, whereas β-adrenergic stimulation overcame this cAMP compartmentation resulting in additional phosphorylation of non-junctional RyR2 clusters. Adenylyl cyclase inhibition, however, abolished the junctional RyR2 phosphorylation and decreased L-type Ca²⁺ channel currents, while FRET imaging showed a rapid cAMP decrease. In conclusion, FRET biosensor imaging identified compartmentalized, constitutively augmented cAMP levels in junctional dyads, driving both the locally increased phosphorylation of RyR2 clusters and larger L-type Ca²⁺ current density in atrial myocytes. This cell-specific cAMP nanodomain is maintained by a constitutively increased adenylyl cyclase activity, contributing to the rapid junctional Ca²⁺-induced Ca²⁺ release, whereas β-adrenergic stimulation overcomes the junctional cAMP compartmentation through cell-wide activation of non-junctional RyR2 clusters.

Chronic Multi-Electrode Electromyography in Snakes

Knowledge about body motion kinematics and underlying muscle contraction dynamics usually derives from electromyographic (EMG) recordings. However, acquisition of such signals in snakes is challenging because electrodes either attached to or implanted beneath the skin may unintentionally be removed by force or friction caused from undulatory motion, thus severely impeding chronic EMG recordings. Here, we present a reliable method for stable subdermal implantation of up to eight bipolar electrodes above the target muscles. The mechanical stability of the inserted electrodes and the overnight coverage of the snake body with a “sleeping bag” ensured the recording of reliable and robust chronic EMG activity. The utility of the technique was verified by daily acquisition of high signal-to-noise activity from all target sites over four consecutive days during stimulus-evoked postural reactions in Amazon tree boas and Western diamondback rattlesnakes. The successful demonstration of the chronic recording suggests that this technique can improve acute experiments by enabling the collection of larger data sets from single individuals.

Frequency modulation of rattlesnake acoustic display affects acoustic distance perception in humans

The estimation of one's distance to a potential threat is essential for any animal's survival. Rattlesnakes inform about their presence by generating acoustic broadband rattling sounds.¹ Rattlesnakes generate their acoustic signals by clashing a series of keratinous segments onto each other, which are located at the tip of their tails.^1-3 Each tail shake results in a broadband sound pulse that merges into a continuous acoustic signal with fast-repeating tail shakes. This acoustic display is readily recognized by other animals^4,5 and serves as an aposematic threat and warning display, likely to avoid being preyed upon.^1,6 The spectral properties of the rattling sound^1,3 and its dependence on the morphology and size of the rattle have been investigated for decades^7-9 and carry relevant information for different receivers, including ground squirrels that encounter rattlesnakes regularly.^10,11 Combining visual looming stimuli with acoustic measurements, we show that rattlesnakes increase their rattling rate (up to about 40 Hz) with decreasing distance of a potential threat, reminiscent of the acoustic signals of sensors while parking a car. Rattlesnakes then abruptly switch to a higher and less variable rate of 60-100 Hz. In a virtual reality experiment, we show that this behavior systematically affects distance judgments by humans: the abrupt switch in rattling rate generates a sudden, strong percept of decreased distance which, together with the low-frequency rattling, acts as a remarkable interspecies communication signal. VIDEO ABSTRACT.

Biallelic variants in YRDC cause a developmental disorder with progeroid features

The highly conserved YrdC domain-containing protein (YRDC) interacts with the well-described KEOPS complex, regulating specific tRNA modifications to ensure accurate protein synthesis. Previous studies have linked the KEOPS complex to a role in promoting telomere maintenance and controlling genome integrity. Here, we report on a newborn with a severe neonatal progeroid phenotype including generalized loss of subcutaneous fat, microcephaly, growth retardation, wrinkled skin, renal failure, and premature death at the age of 12 days. By trio whole-exome sequencing, we identified a novel homozygous missense mutation, c.662T > C, in YRDC affecting an evolutionary highly conserved amino acid (p.Ile221Thr). Functional characterization of patient-derived dermal fibroblasts revealed that this mutation impairs YRDC function and consequently results in reduced t⁶A modifications of tRNAs. Furthermore, we established and performed a novel and highly sensitive 3-D Q-FISH analysis based on single-telomere detection to investigate the impact of YRDC on telomere maintenance. This analysis revealed significant telomere shortening in YRDC-mutant cells. Moreover, single-cell RNA sequencing analysis of YRDC-mutant fibroblasts revealed significant transcriptome-wide changes in gene expression, specifically enriched for genes associated with processes involved in DNA repair. We next examined the DNA damage response of patient’s dermal fibroblasts and detected an increased susceptibility to genotoxic agents and a global DNA double-strand break repair defect. Thus, our data suggest that YRDC may affect the maintenance of genomic stability. Together, our findings indicate that biallelic variants in YRDC result in a developmental disorder with progeroid features and might be linked to increased genomic instability and telomere shortening.

Caveolin3 Stabilizes McT1-Mediated Lactate/Proton Transport in Cardiomyocytes

[Figure: see text].

Fully percutaneous fetoscopic repair of myelomeningocele: 30-month follow-up data

OBJECTIVE

This observational study reports on the postnatal mortality and 30-month outcome of children who underwent fully percutaneous fetoscopic repair of myelomeningocele (MMC) at a single center in Giessen, Germany.

METHODS

Between October 2010 and August 2014, a total of 72 patients underwent fully percutaneous fetoscopic MMC closure at 21 + 0 to 29 + 1 (mean, 23 + 5) weeks' gestation. Of these, 52 (72%) participated in this study; however, 30-month mortality data are available for all 72 children. Children were examined at four timepoints: shortly after birth and at 3 months, 12 months and 30 months of corrected age. The patients underwent age-specific standardized neurological examinations and assessment of leg movements and ambulation at all timepoints. Cognitive and motor development were assessed using the Bayley Scales of Infant Development, second edition (BSID-II), at 30 months.

RESULTS

All 72 children survived the intrauterine procedure, however, four (5.6%) infants died postnatally (including two of the 52 comprising the study cohort). Of the 52 patients included in the study, 11.5% were delivered before the 30^th week of gestation (mean, 33 + 1 weeks) and, of the survivors, 48.1% had ventriculoperitoneal shunt placement. Of the 50 infants that were alive at 30 months, independent ambulation, without orthosis, was feasible for 46%. At 30 months of follow-up, 46% of children presented with a functional level that was at least two segments better than the anatomical level of the lesion. At 30 months, 70% of the children presented with BSID-II psychomotor development index score of ≥ 70 and 80% with BSID-II mental development index score of ≥ 70.

CONCLUSION

Intrauterine repair of MMC by percutaneous fetoscopy shows largely similar outcomes to those reported for open repair, with respect to mortality, prematurity, shunt-placement rates, motor and mental development and free ambulation. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

SnakeStrike: A Low-Cost Open-Source High-Speed Multi-Camera Motion Capture System

Current neuroethological experiments require sophisticated technologies to precisely quantify the behavior of animals. In many studies, solutions for video recording and subsequent tracking of animal behavior form a major bottleneck. Three-dimensional (3D) tracking systems have been available for a few years but are usually very expensive and rarely include very high-speed cameras; access to these systems for research is limited. Additionally, establishing custom-built software is often time consuming – especially for researchers without high-performance programming and computer vision expertise. Here, we present an open-source software framework that allows researchers to utilize low-cost high-speed cameras in their research for a fraction of the cost of commercial systems. This software handles the recording of synchronized high-speed video from multiple cameras, the offline 3D reconstruction of that video, and a viewer for the triangulated data, all functions previously also available as separate applications. It supports researchers with a performance-optimized suite of functions that encompass the entirety of data collection and decreases processing time for high-speed 3D position tracking on a variety of animals, including snakes. Motion capture in snakes can be particularly demanding since a strike can be as short as 50 ms, literally twice as fast as the blink of an eye. This is too fast for faithful recording by most commercial tracking systems and therefore represents a challenging test to our software for quantification of animal behavior. Therefore, we conducted a case study investigating snake strike speed to showcase the use and integration of the software in an existing experimental setup.

Zebrin Expression in the Cerebellum of Two Crocodilian Species

While in birds and mammals the cerebellum is a highly convoluted structure that consists of numerous transverse lobules, in most amphibians and reptiles it consists of only a single unfolded sheet. Orthogonal to the lobules, the cerebellum is comprised of sagittal zones that are revealed in the pattern of afferent inputs, the projection patterns of Purkinje cells, and Purkinje cell response properties, among other features. The expression of several molecular markers, such as aldolase C, is also parasagittally organized. Aldolase C, also known as zebrin II (ZII), is a glycolytic enzyme expressed in the cerebellar Purkinje cells of the vertebrate cerebellum. In birds, mammals, and some lizards (Ctenophoresspp.), ZII is expressed in a heterogenous fashion of alternating sagittal bands of high (ZII+) and low (ZII-) expression Purkinje cells. In contrast, turtles and snakes express ZII homogenously (ZII+) in their cerebella, but the pattern in crocodilians is unknown. Here, we examined the expression of ZII in two crocodilian species (Crocodylus niloticus and Alligator mississippiensis) to help determine the evolutionary origin of striped ZII expression in vertebrates. We expected crocodilians to express ZII in a striped (ZII+/ZII-) manner because of their close phylogenetic relationship to birds and their larger and more folded cerebellum compared to that of snakes and turtles. Contrary to our prediction, all Purkinje cells in the crocodilian cerebellum had a generally homogenous expression of ZII (ZII+) rather than clear ZII+/- stripes. Our results suggest that either ZII stripes were lost in three groups (snakes, turtles, and crocodilians) or ZII stripes evolved independently three times (lizards, birds, and mammals).

Transperineal prostate biopsies without antibiotic prophylaxis: Safety evaluation of the first 65 patients

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Background: There is an ongoing trend towards perineal prostate biopsies for the detection of prostate cancer. For many reasons the issue of antibiotic prophylaxis in prostate biopsies is becoming more important, especially with quinolone antibiotics being excluded from this indication and an increasing antibiotic resistance. Considering that the perineal biopsy is a sterile procedure, not giving antibiotics for prophylaxis seems to be an alluring approach. Methods: At the General Hospital Leverkusen, transperineal (TP) MRI TRUS fusion biopsies are performed using the Ginsburg Protocol with a template and software-guided approach in general anesthesia. Patients received single dose antibiotics (Ciprofloxacine 500 mg) two hours prior to surgery from Jan 2019 to Aug 2019 (group 1). Starting in Sep 2019, no antibiotics were used for prophylaxis (group 2). Surgical disinfection using Povidone-iodine was performed ahead of every procedure. In this study, postoperative infection rates were assessed. Patients were followed up by telephone interview at least two weeks after biopsy and were asked about the need for postoperative antibiotics to treat regular UTI, fever, prostatitis or for readmission to other hospitals. Results: A total of 180 TP biopsies were performed with a median of 22 cores (min 18, max 28). Out of 115 cases with antibiotic prophylaxis, no patient was readmitted to the hospital due to infection or fever. Group 2 included 65 patients. No one was readmitted with fever or prostatitis. At the time of abstract admission 45 out of 65 patients in this group were followed up by telephone interview. None needed antibiotics and none was readmitted to a hospital elsewhere. Conclusions: The study shows an infection rate of 0 % for perineal prostate biopsies with or without antibiotic prophylaxis. The results argue in favor of perineal prostate biopsies and challenge the dogma of prostate biopsies needing an antibiotic prophylaxis irrespective of the approach. However, a larger prospective multicenter study should be initiated to ensure patient safety.

P1230Impact of regulated junctophilin-2 clustering at axial tubule junctions on atrial excitation-contraction coupling and therapeutic implications

Objectives

Atrial dysfunction is highly prevalent and known to significantly aggravate heart failure. While rapid excitation-contraction (EC) coupling depends on axial tubule junctions in atrial myocytes (AMs), the mechanisms leading to atrial loss-of-function remain unclear. Junctophilin-2 (JP2), a tail-anchored protein of the sarcoplasmic reticulum, stabilizes the integrity of ventricular Ca2+ release units, which is disrupted in ventricular myocytes by reduced JP2 expression or proteolysis. Here we aim to characterize the abundance and subcellular localisation of JP2 in AMs, to assess the impact of decreased JP2 expression on atrial remodelling, and to investigate the potential to correct JP2 expression and atrial dysfunction.

Results

We identified 5-fold lower JP2 levels in atrial compared to ventricular tissue in mouse and human hearts by SDS-PAGE. Surprisingly, in AMs, this resulted in subcellular expression of large JP2 clusters at axial tubule junctions together with highly phosphorylated ryanodine receptor (RyR2) channels visualized by STED superresolution microscopy. Importantly, left atrial hypertrophy induced by aortic pressure overload led to an additional strong decrease in JP2 expression compared to sham control, disrupted junctional RyR2 clustering and EC-coupling. This loss-of-function mechanism was confirmed by conditional shRNA-mediated JP2 knockdown. Quantitative image analysis after atrial JP2 knockdown showed a 50% decrease in area overlap between RyR2 and JP2 in AMs (JP2 knockdown 0.03±0.003 μm2 vs. control 0.06±0.004 μm2, p<0.001), and a ∼2-fold increased Ca2+ spark frequency, consistent with decreased left atrial fractional shortening (JP2 knockdown 12.9±0.8% vs. control 16.5±0.9%, p<0.01). Whereas atrial-ventricular dysfunction due to aortic pressure overload resulted in 40% mortality, additional JP2 knockdown exacerbated mortality to 100% (n: 10 control vs. 9 JP2 knockdown mice). In contrast, transgenic JP2 overexpressor mice showed greatly improved atrial contractility without mortality after induced aortic pressure overload (n: 21 control vs. 16 JP2 overexpressor mice). JP2-OE not only augmented atrial RyR2-clustering, but induced the de-novo biogenesis of large poly-adic junctional membrane complexes, which were resolved by STED microscopy via high-resolution cholesterol-based membrane staining in live AMs and electron tomography.

Conclusions

Nanoscale imaging identifies a new subcellular mechanism of significantly limited atrial JP2 protein expression in large clusters at axial tubule junctions. In atrial hypertrophy, JP2 is further decreased with junctional RyR2 cluster disruption leading to impaired Ca2+ release and decreased contractility. Importantly, JP2 overexpression effectively protected from atrial dysfunction, providing a novel therapeutic rationale for atrial cardiomyopathies.

Junctophilin-2 expression rescues atrial dysfunction through polyadic junctional membrane complex biogenesis

Atrial dysfunction is highly prevalent and associated with increased severity of heart failure. While rapid excitation-contraction coupling depends on axial junctions in atrial myocytes, the molecular basis of atrial loss of function remains unclear. We identified approximately 5-fold lower junctophilin-2 levels in atrial compared with ventricular tissue in mouse and human hearts. In atrial myocytes, this resulted in subcellular expression of large junctophilin-2 clusters at axial junctions, together with highly phosphorylated ryanodine receptor (RyR2) channels. To investigate the contribution of junctophilin-2 to atrial pathology in adult hearts, we developed a cardiomyocyte-selective junctophilin-2-knockdown model with 0 mortality. Junctophilin-2 knockdown in mice disrupted atrial RyR2 clustering and contractility without hypertrophy or interstitial fibrosis. In contrast, aortic pressure overload resulted in left atrial hypertrophy with decreased junctophilin-2 and RyR2 expression, disrupted axial junctions, and atrial fibrosis. Whereas pressure overload accrued atrial dysfunction and heart failure with 40% mortality, additional junctophilin-2 knockdown greatly exacerbated atrial dysfunction with 100% mortality. Strikingly, transgenic junctophilin-2 overexpression restored atrial contractility and survival through de novo biogenesis of polyadic junctional membrane complexes maintained after pressure overload. Our data show a central role of junctophilin-2 cluster disruption in atrial hypertrophy and identify transgenic augmentation of junctophilin-2 as a disease-mitigating rationale to improve atrial dysfunction and prevent heart failure deterioration.

Axial Tubule Junctions Activate Atrial Ca2+ Release Across Species

Rationale: Recently, abundant axial tubule (AT) membrane structures were identified deep inside atrial myocytes (AMs). Upon excitation, ATs rapidly activate intracellular Ca²⁺ release and sarcomeric contraction through extensive AT junctions, a cell-specific atrial mechanism. While AT junctions with the sarcoplasmic reticulum contain unusually large clusters of ryanodine receptor 2 (RyR2) Ca²⁺ release channels in mouse AMs, it remains unclear if similar protein networks and membrane structures exist across species, particularly those relevant for atrial disease modeling.

Objective: To examine and quantitatively analyze the architecture of AT membrane structures and associated Ca²⁺ signaling proteins across species from mouse to human.

Methods and Results: We developed superresolution microscopy (nanoscopy) strategies for intact live AMs based on a new custom-made photostable cholesterol dye and immunofluorescence imaging of membraneous structures and membrane proteins in fixed tissue sections from human, porcine, and rodent atria. Consistently, in mouse, rat, and rabbit AMs, intact cell-wide tubule networks continuous with the surface membrane were observed, mainly composed of ATs. Moreover, co-immunofluorescence nanoscopy showed L-type Ca²⁺ channel clusters adjacent to extensive junctional RyR2 clusters at ATs. However, only junctional RyR2 clusters were highly phosphorylated and may thus prime Ca²⁺ release at ATs, locally for rapid signal amplification. While the density of the integrated L-type Ca²⁺ current was similar in human and mouse AMs, the intracellular Ca²⁺ transient showed quantitative differences. Importantly, local intracellular Ca²⁺ release from AT junctions occurred through instantaneous action potential propagation via transverse tubules (TTs) from the surface membrane. Hence, sparse TTs were sufficient as electrical conduits for rapid activation of Ca²⁺ release through ATs. Nanoscopy of atrial tissue sections confirmed abundant ATs as the major network component of AMs, particularly in human atrial tissue sections.

Conclusion: AT junctions represent a conserved, cell-specific membrane structure for rapid excitation-contraction coupling throughout a representative spectrum of species including human. Since ATs provide the major excitable membrane network component in AMs, a new model of atrial “super-hub” Ca²⁺ signaling may apply across biomedically relevant species, opening avenues for future investigations about atrial disease mechanisms and therapeutic targeting.

Synaptic convergence of afferent inputs in primary infrared-sensitive nucleus (LTTD) neurons of rattlesnakes (Crotalinae) as the origin for sensory contrast enhancement

Pitvipers have a specialized sensory system in the upper jaw to detect infrared (IR) radiation. The bilateral pit organs resemble simple pinhole cameras that map IR objects onto the sensory epithelium as blurred representations of the environment. Trigeminal afferents transmit information about changing temperature patterns as neuronal spike discharge in a topographic manner to the hindbrain nucleus of the lateral descending trigeminal tract (LTTD). A presumed, yet so far unknown neuronal connectivity within this central nucleus exerts a synaptic computation that constrains the relatively large receptive field of primary afferent fibers. Here, we used intracellular recordings of LTTD neurons in isolated rattlesnake brains to decipher the spatio-temporal pattern of excitatory and inhibitory responses following electrical stimulation of single and multiple peripheral pit organ-innervating nerve branches. The responses of individual neurons consisted of complex spike sequences that derived from spatially and temporally specific interactions between excitatory and inhibitory synaptic inputs from the same as well as from adjacent peripheral nerve terminal areas. This pattern complies with a central excitation that is flanked by a delayed lateral inhibition, thereby enhancing the contrast of IR sensory input, functionally reminiscent of the computations for contrast enhancement in the peripheral visual system.

Beyond the 3'UTR binding-microRNA-induced protein truncation via DNA binding

Here, we present a miR mechanism which is active in the nucleus and is essential for the production of intron included, C-terminal truncated and biologically active proteins, like e.g. Vim3. We exemplified this mechanism by miRs, miR-15a and miR-498, which are overexpressed in clear cell renal carcinoma or oncocytoma.

Both miRs directly interact with DNA in an intronic region, leading to transcriptional stop, and therefore repress the full length version of the pre-mRNA, resulting in intron included truncated proteins (Mxi-2 and Vim3). A computational survey shows that this miR:DNA interactions mechanism may be generally involved in regulating the human transcriptome, with putative interaction sites in intronic regions for over 1000 genes.

In this work, an entirely new mechanism is revealed how miRs can repress full length protein translation, resulting in C-terminal truncated proteins.

68-Ga-PSMA-PET in lymph node staging in PSA recurrent prostate cancer-does the primary influence the result?

210

Background: Prostate cancer is the most common cancer in western countries. 68Ga PSMA-PET is the most accurate tool to detect lymph node metastases even at low PSA values. Salvage lymph node dissection prolongs biochemical recurrent free survival, whereas salvage radical prostatectomy has the potential to achieve long term tumor control at least in node negative disease. We compared the diagnostic value of 68Ga-PSMA PET in patients with biochemical recurrence after radical prostatectomy an salvage radiotherapy (Group1) and in patients with local recurrence after radiotherapy (Group2) to evaluate the influence of the primary. Methods: We retrospectively reviewed 57 and 31 patients in Group I and II respectively. In Group I a salvage lymph node dissection was performed on the side of the positive PSMA-staining. In Group II an extended pelvic lymph node dissection was performed in addiction to a salvage radical prostatectomy. Sensitivity, Specificity, posisive and negative predictive value as well as accuracy of PSMA-PET was calculated per lesion. Results: A total of 649 (2-32) and 515 (3-29) lymph nodes had been dissected. In 39 (68%) and 11(35,5%) at least one positive lymph node could be found. Mean diameter of the metastases was 0,81 (0,1-2,6)cm and 0,8(0,1-2) cm respectively. Sensitivity, Specificity, pos and neg. predicitve value as well as accuracy in Group I and two are 85, 96, 77, 98, 94,6 and 40, 100, 100, 98, 97,6%. Conclusions: In salvage surgeries in PCA good diagnostic tools to identify lymph node metastases are mandatory. With the primary in situ there is a significant reduced sensitivity of only 40% to identify positive nodes. The specific role of the primary tumor is not yet known.

Vimentin 3 and endothelin in prostate cancer

349

Background: An upregulation of vimentin 3, a truncated version of the full length vimentin, with an unknown function, was previously described by our group, in a direct dependency of increased ET-1 levels. We analyzed now vimentin 3 in further genitourinary cancers. Here, we describe our findings how vimentin 3 is part of the signaling pathways from Endothelin-1 (ET-1) and the Endothelin-A-Receptor (ETAR) and how it correlates with aggressive tumor behavior in a PCa cell culture and in human tissue and serum samples from PCa patients. Methods: DU145 cells were cultured. We stimulated with ET-1 with and without artificial downregulation of the ETAR, the ETBR or both receptors. A scratch assay was performed to demonstrate the influence of ET-1. Proteins were then extracted and WB for vimentin full length and vimentin 3 was performed. Additionally we analyzed ET-1 and vimentin 3 in serum from prostate cancer patients using ELISA and we did IF and IHC staining for vimentin 3 in human prostate cancer tissue. Results: Treatment with ET-1 and downregulation of the ETBR lead to a significant increased migration of DU145 cells after 3 and 6 h. The corresponding WB showed increased vimentin 3. ELISA showed increased levels of ET-1 in samples of prostate cancer patients compared to patients with no cancer history. ELISA could also demonstrate elevated levels of vimentin 3 in serum of patients with local disease and significantly elevated values in metastatic prostate cancer patients compared to patients with no cancer history. Conclusions: The data presented shows that ET-1 stimulation leads to overexpression of vimentin 3 in prostate cancer cell cultures and a concomitant aggressive biological behavior. Here we previously described the direct interaction of Vimentin 3 in prostate cancer and the activation mechanism via ET-1 and the ETAR. IHC, IF show an upregulation of the truncated variant Vimentin3 in tissue samples. In an Vimentin 3 ELISA we could show that this truncated variant is increased and therefore represents a potential biomarker. Highest values of vimentin 3 were measured using ELISA in serum of patients with recurrent and metastatic disease also suggesting that vimentin 3 correlates with aggressive tumor behavior.

The role of reference pathology to assess MRI-TRUS fusion prostate biopsies in a tertiary referral center

32

Background: Risk stratification for patients diagnosed with prostate cancer (PCa) through MR-TRUS fusion biopsy still relies on Gleason (GL) grading of the biopsy specimens. GL grading of the same sample can differ between pathologists. In our tertiary high-volume center GL grading of the biopsy specimens is crucial for further therapy planning. Methods: Reference pathology of 42 patients after transperineal MR-TURS fusion plus saturation biopsy was assessed by one specialized genitourinary pathologist. GL grading of the original pathology and the reference pathology for the saturation and targeted biopsy cores were compared. Risk groups for this study were set as GL 6 for low, GL 7a and GL 7b for intermediate and GL 8, GL 9 and GL 10 for high-risk. Results: In 42 patients 49 lesions were identified by mpMRI (PI-RADS 3-5) in which 150 biopsy cores were taken. In addition, 709 cores were taken as saturation biopsies. The highest GL grading per patient differed in 18 (43 %) of the cases. In 16 cases, there was a difference within the targeted biopsies but only in 8 cases there was a difference in the saturation biopsies. In 6 cases both saturation and fusion biopsies were different. Taking risk stratification into account there was a misclassification with low- and intermediate risk in 9 (21 %) cases, an intermediate- and high risk in 2 cases and a misclassification within the same risk group in 6 (14 %) cases. In 16 of the 18 differences there was an upgrading of the Gleason score by the reference pathologist whereas only in 2 cases there was a downgrading. Conclusions: The data shows that in times of mpMRIs and transperineal MRI-TRUS fusion biopsies it still is the GL score graded by the pathologist who accounts for many potential therapy plan mistakes. In this study 21 % of the patients were misclassified as GL 6 while reference pathology graded for GL 7a or GL 7b. The demonstrated data suggests that there should be a reference pathology at least for every GL 6 cancer and that the quality of GL grading should be monitored. Also this data again addresses the need for a better risk stratification irrespective of the GL score that can be done in a more objective way with less potential for misclassification.

Functional outcome and quality of life in patients undergoing salvage radical prostatectomy (SRPE)

212

Background: Salvage radical prostatectomy is one option for patients with locally recurrent disease with proven long term oncologic control. There are concerns about worse functional results due to fibrotic tissue after radiotherapy and patients are treated with palliative systemic androgendreptivation. We retrospectively analyzed continence and quality of life in patients undergoing SRPE. Methods: After biopsy proven local recurrent prostate cancer 138 patients were offered SRPE and extended lymphadenectomy. Continence and quality of life had been collected before 6 and 12 months after surgery. Validated questionaires with ICIQ and EORTC qlq 30 had been used. Results: Präoperatively at 6 monts and 12 months the feed back was available in 93, 84 and 82 patients respectively. Präoperatively there was no or mild incontinence in 38(40.8%), moderate in 33 (35.5%) and strong incontinence in 22 (23.7%) of the patients. There is a significant decrease in the rate of continence after 6 and 12 months to no or mild in 19 (23.1%), moderate in 19 (23.2%) and strong incontinence in 44 (53.7%) of the patients. In 5 patients an artifitial sphinkter was implanted. Quality of life did not change significantly before and 12 months after surgery. Median value of Question 30 was 6 and five respectively. Conclusions: Patients need to be informed about a worse functional outcome and the potential need for further surgical interventions as artificial sphinkter implantion compared to primary radical prostatectomy. Quality of life seems to be affected only moderatly. Nevertheless there is already a rather high rate of any incontinence before surgery that needs to be taken into account.

68-Ga-PSMA-PET in the diagnosis of local recurrent disease after radiotherapy in patients with prostate cancer

213

Background: For planning salvage procedures in recurrent prostate cancer accurate diagnostic tools are needed. Till now in patients suspicious for isolated local recurrent cancer invasive biopsy was needed. 68-Ga-PSMA-PET is frequently used to identify even small metastatic deposits. We analyzed the diagnostic value to identify local recurrence in patients after radiotherapy undergoing salvage radical prostatectomy, sRPE. Methods: We retrospectively reviewed patients undergoing sRPE with 68-Ga-PSMA-PET as preoperative staging. All patients underwent sRPE and extended lymph node dissection. Sensitivity, Specificity, pos and neg predictive value had been calculated per patient and per prostate lobe. Results: 37 patients with preoperative 68-Ga-PSMA-PEt could be identified. In all but one at least in one lobe PSMA staining could be identified. Mean tumor volume per prostate lobe was 6.22 (0.1-24)ml. Sensitivity, Specificity, neg and pos predictive value per lobe is 80%, 75%, 32% and 96%. Sensitivity to identify cancer recurrence per person irrespective of the side is 95% with a pos predictive value of 100%. Conclusions: 68-Ga-PSMA-PET seems to have a very high diagnistic value to identify local recurrence after radiotherapy. After validation of our experience an invasive biopsy to proof cancer recurrence might be spared.

[Reconstructive surgery of ureteral stricture disease]

Ureterstrikturen mit konsekutiver Hydronephrose können sich als Folge endourologischer oder operativer Manipulationen, nach intra- oder extraluminalen entzündlichen Prozessen, als Folge einer Radiotherapie der Nachbarorgane oder auch nach Steinabgängen entwickeln. Anatomische Lage, Längenausdehnung, zugrundeliegende Ursache, Alter und Komorbiditäten des Patienten sowie die bereits durchgeführten Voroperationen im Peritonealraum, Retroperitoneum oder kleinem Becken müssen im Rahmen der Planung einer operativen Korrektur berücksichtigt werden. An Therapieoptionen stehen von der End-zu-End Anastomose über die Ureterolyse und die Ureterneoimplantation bis hin zum Ureter-Ileum-Interponat oder der renalen Autotransplantation eine Vielzahl chirurgischer Techniken zur Verfügung, die individuell abgewogen werden müssen und von dem Chirurgen eine große operative Erfahrung erfordern. Neben den operativ-rekonstruktiven Verfahren müssen auch minimal-invasive Therapieverfahren wie die Implantation selbst-expandierender Stents oder eines pyelovesikalen Bypass in das Therapiespektrum mit einbezogen werden. Bei geeigneter Indikation und entsprechender operativer Erfahrung sind die einzelnen Verfahren mit einer hohen Erfolgsrate von über 90 % und einer signifikanten Komplikationsrate von < 5 % vergesellschaftet. Es ist die Zielsetzung dieses Artikels die verschiedenen Therapieverfahren kritisch darzustellen und Empfehlungen für eine individuelle, differenzialtherapeutische Entscheidung aufzuzeigen.

Cuticular microstructures turn specular black into matt black in a stick insect

The stick insect Peruphasma schultei stands out from other insects by its deep matt black cuticle. We tested whether the appearance of P. schultei is due to microstructures of the cuticle, a phenomenon that has recently been described for the velvet black scales of the Gaboon viper. The shiny black stick insect Anisomorpha paromalus served as a control. We found that the P. schultei cuticle is characterised by two different types of microstructures, tall elevations with a maximum size of 18 μm and small structures with a height of 4 μm. Other than in the snake, P. schultei microstructures do not bear nanostructures. The microstructures scatter light independently of the viewing angle. This causes the matt appearance of the cuticle, whereas pigments are responsible for the black colouration, resulting in a maximum reflectance of 2.8% percent. The microstructures also cause the hydrophobic properties of the cuticle with contact angles near 130°. Resin replicas and bleaching of the cuticle strongly support these results. Moreover, the matt black cuticle has a higher heat absorption compared to the control. We discuss the selective benefit of the matt black appearance of P. schultei in the context of behaviour, ecology and phylogeny.

Mice lacking WRB reveal differential biogenesis requirements of tail-anchored proteins in vivo

Tail-anchored (TA) proteins are post-translationally inserted into membranes. The TRC40 pathway targets TA proteins to the endoplasmic reticulum via a receptor comprised of WRB and CAML. TRC40 pathway clients have been identified using in vitro assays, however, the relevance of the TRC40 pathway in vivo remains unknown. We followed the fate of TA proteins in two tissue-specific WRB knockout mouse models and found that their dependence on the TRC40 pathway in vitro did not predict their reaction to receptor depletion in vivo. The SNARE syntaxin 5 (Stx5) was extremely sensitive to disruption of the TRC40 pathway. Screening yeast TA proteins with mammalian homologues, we show that the particular sensitivity of Stx5 is conserved, possibly due to aggregation propensity of its cytoplasmic domain. We establish that Stx5 is an autophagy target that is inefficiently membrane-targeted by alternative pathways. Our results highlight an intimate relationship between the TRC40 pathway and cellular proteostasis.

Axial tubule junctions control rapid calcium signaling in atria

The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters. In mouse AM, AT structures triggered Ca2+ release from the SR approximately 2 times faster at the AM center than at the surface. Rapid Ca2+ release correlated with colocalization of highly phosphorylated RyR2 clusters at AT-SR junctions and earlier, more rapid shortening of central sarcomeres. In contrast, mice expressing phosphorylation-incompetent RyR2 displayed depressed AM sarcomere shortening and reduced in vivo atrial contractile function. Moreover, left atrial hypertrophy led to AT proliferation, with a marked increase in the highly phosphorylated RyR2-pS2808 cluster fraction, thereby maintaining cytosolic Ca2+ signaling despite decreases in RyR2 cluster density and RyR2 protein expression. AT couplon "super-hubs" thus underlie faster excitation-contraction coupling in health as well as hypertrophic compensatory adaptation and represent a structural and metabolic mechanism that may contribute to contractile dysfunction and arrhythmias.

Superresolution modeling of calcium release in the heart

Stable calcium-induced calcium release (CICR) is critical for maintaining normal cellular contraction during cardiac excitation-contraction coupling. The fundamental element of CICR in the heart is the calcium (Ca²⁺) spark, which arises from a cluster of ryanodine receptors (RyR). Opening of these RyR clusters is triggered to produce a local, regenerative release of Ca²⁺ from the sarcoplasmic reticulum (SR). The Ca²⁺ leak out of the SR is an important process for cellular Ca²⁺ management, and it is critically influenced by spark fidelity, i.e., the probability that a spontaneous RyR opening triggers a Ca²⁺ spark. Here, we present a detailed, three-dimensional model of a cardiac Ca²⁺ release unit that incorporates diffusion, intracellular buffering systems, and stochastically gated ion channels. The model exhibits realistic Ca²⁺ sparks and robust Ca²⁺ spark termination across a wide range of geometries and conditions. Furthermore, the model captures the details of Ca²⁺ spark and nonspark-based SR Ca²⁺ leak, and it produces normal excitation-contraction coupling gain. We show that SR luminal Ca²⁺-dependent regulation of the RyR is not critical for spark termination, but it can explain the exponential rise in the SR Ca²⁺ leak-load relationship demonstrated in previous experimental work. Perturbations to subspace dimensions, which have been observed in experimental models of disease, strongly alter Ca²⁺ spark dynamics. In addition, we find that the structure of RyR clusters also influences Ca²⁺ release properties due to variations in inter-RyR coupling via local subspace Ca²⁺ concentration ([Ca²⁺]_ss). These results are illustrated for RyR clusters based on super-resolution stimulated emission depletion microscopy. Finally, we present a believed-novel approach by which the spark fidelity of a RyR cluster can be predicted from structural information of the cluster using the maximum eigenvalue of its adjacency matrix. These results provide critical insights into CICR dynamics in heart, under normal and pathological conditions.

Pulmonary Vasoreactivity to Materno-Fetal Hyperoxygenation Testing in Fetuses with Hypoplastic Left Heart

PURPOSE

The aim of the study was to describe the response of fetal lung vasculature to maternal hyperoxygenation (MH) in the case of prenatally diagnosed hypoplastic left heart (HLH) with intact or restrictive (IAS/RAS) and without restriction of the atrial septum. Furthermore, the ability of MH to differentiate between newborns with HLH who do not require immediate atrial septostomy and newborns who will undergo immediate left atrial septoplasty after birth was evaluated.

MATERIALS AND METHODS

Cross-sectional prospective study of fetuses ≥ 26 weeks of gestation with prenatally diagnosed HLH. Lung perfusion (LP) was qualitatively assessed by color Doppler interrogation and LP was quantitatively measured using the pulsatility index for veins (PIV). Measurements were performed both with the mother breathing room air (LPRA) and after receiving 100% oxygen for 10 minutes (LPMH). The oxygen test was defined as positive if MH led to an increase in lung perfusion and as negative if MH did not lead to an increase.

RESULTS

A total number of 22 pregnancies with hypoplasia of the left heart structures were included. 6/20 cases presented with an intact or restrictive atrial septum (IAS/RAS). All of these fetuses presented with a reduced LPRA. MH led to an increase in LP in 2/6 cases. The overall 30-day-survival rate was 83.3% (5/6). In 14/20 fetuses an open septum was detected. 11 cases had a normal LPRA, and the LPRA was reduced in 3/14 fetuses. The overall 30-day-survival rate was 92.9% (13/14).

CONCLUSION

MH might be a useful adjunct in the assessment of pulmonary vasculopathy in fetuses with HLH.

Percutaneous minimally invasive fetoscopic surgery for spina bifida aperta. Part III: neurosurgical intervention in the first postnatal year

OBJECTIVE

To evaluate the need for postnatal neurosurgical intervention after fetoscopic patch coverage of spina bifida aperta (SBA).

METHODS

This was a retrospective analysis of a cohort of 71 fetuses which underwent minimally invasive fetoscopic patch coverage of SBA between 21 + 0 and 29 + 1 weeks of gestation. Postnatal neurosurgical procedures were classified into two types: re-coverage of the SBA within the first 3 months following birth, and shunt placement as treatment of associated hydrocephalus within the first year.

RESULTS

Location of the SBA was lumbosacral in 59 cases, lumbar in seven, thoracic in three and sacral in two. In total, 20/71 (28%) patients underwent early postnatal neurosurgical intervention by means of re-coverage of the SBA. This was performed because of cerebrospinal fluid leakage in seven (35%), adhesions with functional deterioration in three (15%), incomplete coverage in five (25%) and skin defect in five (25%) cases. Ventriculoperitoneal shunt placement within 1 year was required in 32 (45%) cases and was preceded by ventriculostomy in two. Three (4%) infants needed Chiari decompression surgery in the first 12 months following birth, because of syringomyelia or gait disturbance.

CONCLUSIONS

Fetoscopic patch coverage of SBA may require postnatal re-coverage in some cases. In most cases, conservative wound treatment shows good results, without requiring neurosurgical intervention. The low 1-year-shunt rate is comparable to data of the Management of Myelomeningocele Study and lower compared with published data of patients with postnatal only coverage of SBA.

On the Adjacency Matrix of RyR2 Cluster Structures

In the heart, electrical stimulation of cardiac myocytes increases the open probability of sarcolemmal voltage-sensitive Ca2+ channels and flux of Ca2+ into the cells. This increases Ca2+ binding to ligand-gated channels known as ryanodine receptors (RyR2). Their openings cause cell-wide release of Ca2+, which in turn causes muscle contraction and the generation of the mechanical force required to pump blood. In resting myocytes, RyR2s can also open spontaneously giving rise to spatially-confined Ca2+ release events known as "sparks." RyR2s are organized in a lattice to form clusters in the junctional sarcoplasmic reticulum membrane. Our recent work has shown that the spatial arrangement of RyR2s within clusters strongly influences the frequency of Ca2+ sparks. We showed that the probability of a Ca2+ spark occurring when a single RyR2 in the cluster opens spontaneously can be predicted from the precise spatial arrangements of the RyR2s. Thus, "function" follows from "structure." This probability is related to the maximum eigenvalue (λ1) of the adjacency matrix of the RyR2 cluster lattice. In this work, we develop a theoretical framework for understanding this relationship. We present a stochastic contact network model of the Ca2+ spark initiation process. We show that λ1 determines a stability threshold for the formation of Ca2+ sparks in terms of the RyR2 gating transition rates. We recapitulate these results by applying the model to realistic RyR2 cluster structures informed by super-resolution stimulated emission depletion (STED) microscopy. Eigendecomposition of the linearized mean-field contact network model reveals functional subdomains within RyR2 clusters with distinct sensitivities to Ca2+. This work provides novel perspectives on the cardiac Ca2+ release process and a general method for inferring the functional properties of transmembrane receptor clusters from their structure.