Limitations of fluorescent timer protein maturation kinetics to isolate transcriptionally synchronized human neural progenitor cells

Differentiation of human pluripotent stem cells (hPSCs) into subtype-specific neurons holds substantial potential for disease modeling in vitro. For successful differentiation, a detailed understanding of the transcriptional networks regulating cell fate decisions is critical. The heterochronic nature of neurodevelopment, during which distinct cells in the brain and during in vitro differentiation acquire their fates in an unsynchronized manner, hinders pooled transcriptional comparisons. One approach is to "translate" chronologic time into linear developmental and maturational time. Simple binary promotor-driven fluorescent proteins (FPs) to pool similar cells are unable to achieve this goal, due to asynchronous promotor onset in individual cells. We tested five fluorescent timer (FT) molecules expressed from the endogenous paired box 6 (PAX6) promoter in 293T and human hPSCs. Each of these FT systems faithfully reported chronologic time in 293T cells, but none of the FT constructs followed the same fluorescence kinetics in human neural progenitor cells.

Limitations of fluorescent timer protein maturation kinetics to isolate transcriptionally synchronized cortically differentiating human pluripotent stem cells

Differentiation of human pluripotent stem cells (hPSC) into distinct neuronal populations holds substantial potential for disease modeling in vitro, toward both elucidation of pathobiological mechanisms and screening of potential therapeutic agents. For successful differentiation of hPSCs into subtype-specific neurons using in vitro protocols, detailed understanding of the transcriptional networks and their dynamic programs regulating endogenous cell fate decisions is critical. One major roadblock is the heterochronic nature of neurodevelopment, during which distinct cells and cell types in the brain and during in vitro differentiation mature and acquire their fates in an unsynchronized manner, hindering pooled transcriptional comparisons. One potential approach is to "translate" chronologic time into linear developmental and maturational time. Attempts to partially achieve this using simple binary promotor-driven fluorescent proteins (FPs) to pool similar cells have not been able to achieve this goal, due to asynchrony of promotor onset in individual cells. Toward solving this, we generated and tested a range of knock-in hPSC lines that express five distinct dual FP timer systems or single time-resolved fluorescent timer (FT) molecules, either in 293T cells or in human hPSCs driving expression from the endogenous paired box 6 (PAX6) promoter of cerebral cortex progenitors. While each of these dual FP or FT systems faithfully reported chronologic time when expressed from a strong inducible promoter in 293T cells, none of the tested FP/FT constructs followed the same fluorescence kinetics in developing human neural progenitor cells, and were unsuccessful in identification and isolation of distinct, developmentally synchronized cortical progenitor populations based on ratiometric fluorescence. This work highlights unique and often surprising expression kinetics and regulation in specific cell types differentiating from hPSCs.

BigNeuron: a resource to benchmark and predict performance of algorithms for automated tracing of neurons in light microscopy datasets

BigNeuron is an open community bench-testing platform with the goal of setting open standards for accurate and fast automatic neuron tracing. We gathered a diverse set of image volumes across several species that is representative of the data obtained in many neuroscience laboratories interested in neuron tracing. Here, we report generated gold standard manual annotations for a subset of the available imaging datasets and quantified tracing quality for 35 automatic tracing algorithms. The goal of generating such a hand-curated diverse dataset is to advance the development of tracing algorithms and enable generalizable benchmarking. Together with image quality features, we pooled the data in an interactive web application that enables users and developers to perform principal component analysis, t-distributed stochastic neighbor embedding, correlation and clustering, visualization of imaging and tracing data, and benchmarking of automatic tracing algorithms in user-defined data subsets. The image quality metrics explain most of the variance in the data, followed by neuromorphological features related to neuron size. We observed that diverse algorithms can provide complementary information to obtain accurate results and developed a method to iteratively combine methods and generate consensus reconstructions. The consensus trees obtained provide estimates of the neuron structure ground truth that typically outperform single algorithms in noisy datasets. However, specific algorithms may outperform the consensus tree strategy in specific imaging conditions. Finally, to aid users in predicting the most accurate automatic tracing results without manual annotations for comparison, we used support vector machine regression to predict reconstruction quality given an image volume and a set of automatic tracings.

An unbiased AAV-STARR-seq screen revealing the enhancer activity map of genomic regions in the mouse brain in vivo

Enhancers are important cis-regulatory elements controlling cell-type specific expression patterns of genes. Furthermore, combinations of enhancers and minimal promoters are utilized to construct small, artificial promoters for gene delivery vectors. Large-scale functional screening methodology to construct genomic maps of enhancer activities has been successfully established in cultured cell lines, however, not yet applied to terminally differentiated cells and tissues in a living animal. Here, we transposed the Self-Transcribing Active Regulatory Region Sequencing (STARR-seq) technique to the mouse brain using adeno-associated-viruses (AAV) for the delivery of a highly complex screening library tiling entire genomic regions and covering in total 3 Mb of the mouse genome. We identified 483 sequences with enhancer activity, including sequences that were not predicted by DNA accessibility or histone marks. Characterizing the expression patterns of fluorescent reporters controlled by nine candidate sequences, we observed differential expression patterns also in sparse cell types. Together, our study provides an entry point for the unbiased study of enhancer activities in organisms during health and disease.

126 The Theatre Training Checklist: A Toolkit to Improve Operative Training

Aim

The operating theatre is expensive, costing approximately £1200 per hour to run. It is a crucial learning environment for many different trainees: anaesthetists, surgeons, operation department practitioners, etc. For individuals to achieve their training requirements, the operating theatre as a training environment must be shared between all trainees, requiring excellent teamwork and leadership. This could be improved by the adoption of innovative training strategies.

Method

The Theatre Training Checklist is a simple framework that aims to facilitate awareness, understanding, coordination and cooperation of training for all team members. It is a practical strategy that can be adopted in any setting. Usually, trainers discuss informally with their trainees about their individual skills, experience, expectations and what is achievable in a theatre list. However, there is currently limited opportunity to discuss this between different disciplines and the wider team. This tool aims to refine communication, optimize training, manage expectations, and ensure equity across the board.

Results

The checklist is completed at the start of the list during the theatre brief. It identifies all trainees and their specific needs within the operating theatre session to the whole team. An agreed strategy is developed on how to achieve identified training goals. Feedback undertaken from the MDT after local trailing of the checklist has been positive.

Conclusions

The toolkit is available for use and consists of the checklist tool and an instructional video. The checklist is being piloted in some centres and we hope to have the opportunity to present some early findings to the ASiT Innovation Summit.

Rapid nucleus-scale reorganization of chromatin in neurons enables transcriptional adaptation for memory consolidation

The interphase nucleus is functionally organized in active and repressed territories defining the transcriptional status of the cell. However, it remains poorly understood how the nuclear architecture of neurons adapts in response to behaviorally relevant stimuli that trigger fast alterations in gene expression patterns. Imaging of fluorescently tagged nucleosomes revealed that pharmacological manipulation of neuronal activity in vitro and auditory cued fear conditioning in vivo induce nucleus-scale restructuring of chromatin within minutes. Furthermore, the acquisition of auditory fear memory is impaired after infusion of a drug into auditory cortex which blocks chromatin reorganization in vitro. We propose that active chromatin movements at the nucleus scale act together with local gene-specific modifications to enable transcriptional adaptations at fast time scales. Introducing a transgenic mouse line for photolabeling of histones, we extend the realm of systems available for imaging of chromatin dynamics to living animals.

941 Post-Operative Outcomes of Patients Undergoing Surgery During the Acceleration Period of COVID-19 Infection

Introduction

There are concerns around the safety of performing surgery during COVID-19 outbreaks with few sources of robust evidence.

Method

We analysed 5020 consecutive patients who underwent surgery during the acceleration phase of COVID-19 at our hospital from 31st January to 13th April 2020. Data were also analysed for all patients who had a COVID-19 positive test result during the same study period.

Results

156 patients (3%) developed COVID-19 symptoms after surgery; 28 patients (<1%) subsequently had a positive swab result. All-cause mortality was 44 patients (0.9%); 33 deaths (75%) were due to non COVID-19 diagnoses. There were no adverse COVID-19 related outcomes in any of the 648 patients who had cancer operations. Of 28 COVID-19 positive patients, 11 died (8 orthopaedic, 2 urology, 1 vascular surgery) of which 10 had an emergency admission; all were over 70 years of age. Recent surgery was not an independent prognostic factor for survival after COVID-19 infection. 12% of positive COVID-19 swabs were from long-stay patients.

Conclusions

Of 5020 operative patients, 0.2% died from COVID-19 and most complications were not related to the infection. With careful consideration, surgery can be provided safely during times of COVID-19 outbreaks with particular emphasis on avoiding in-hospital transmission.

920 Long Term Outcomes After Resection of A 'Normal' Appendix

Introduction

Recent studies have suggested that there should be diagnostic confirmation of appendicitis prior to surgical resection to reduce the rate of negative (normal) appendicectomy. There are few long-term analyses of morbidity after negative appendicectomy.

Method

All appendicectomy specimens removed for suspected appendicitis from June 2010 to August 2015 at a single-centre surgical unit were identified. Patients with a histologically 'normal' appendix were analysed. Demographics, pre-operative and operative details and post-operative outcomes (Clavien-Dindo system) were recorded. Minimum follow-up was 5 years.

Results

There were 1977 patients. Most (1938 patients, 98%) had a laparoscopic procedure. There were 241 normal specimens (12.1%); none of these patients had pre-operative CT imaging. Thirty-two patients had at least one re-admission in the 5 years after surgery; 12 of these patients had multiple re-admissions (range, 2-5 re-admissions). 22 patients (69%) had a re-admission within 30 days after primary surgery. 4 patients (&lt;1%) required further surgery and mortality was 0%. 6 patients (2%) had a Grade III complication, and none had a Grade IV complication.

Conclusions

There was low long-term morbidity after negative appendicectomy in this study. The cost of confirming a normal diagnosis by way of mandatory pre-operative CT does not represent a cost-effective method of management.

Gemeindenotfallsanitäter als innovatives Einsatzmittel in der Notfallversorgung – erste Ergebnisse einer Beobachtungsstudie

Hintergrund

Rettungsdienst und Notaufnahmen werden zunehmend durch nichtlebensbedrohlich erkrankte Patienten belastet. In England und den USA wurden zur Versorgung vor Ort bereits vor einigen Jahren Community-paramedic-Systeme etabliert.

Auf diesen Konzepten basierend wurde ein an das deutsche Rettungswesen adaptierte System „Gemeindenotfallsanitäter“ (G-NFS) entwickelt. Das Ziel des G‑NFS ist, eine unnötige Disponierung höherwertiger Rettungsmittel zu reduzieren.

Ziel

Deskriptive Analyse der in den ersten 12 Monaten erhobenen Daten.

Methodik

Es handelt sich um eine retrospektive Beobachtungsstudie auf Basis der Einsatzdokumentation im Jahr 2019.

Ergebnisse

Es wurden 3703 Einsatzprotokolle ausgewertet. Das Durchschnittsalter betrug 62,2 ± 24,7 Jahre. Bei 2186 (61,1 %) Patienten wurde die Behandlungspriorität „0“ gewählt, d. h.: Es lag keine Dringlichkeit der Versorgung vor. 2134 (59 %) Patienten benötigten kein weiteres Rettungsmittel, eine ambulante Versorgung vor Ort war ausreichend. Am häufigsten wurde den Patienten die Vorstellung beim Hausarzt (n = 1422, 38 %) sowie die Vorstellung in der Notaufnahme (n = 1222, 33 %) empfohlen. Aus Sicht der G‑NFS wurden 3058 (85 %) Einsätze von den Leitstellendisponenten richtig kategorisiert.

Diskussion

Durch die gezielte Alarmierung der neu geschaffenen Ressource „Gemeindenotfallsanitäter“ können Patienten ambulant vor Ort versorgt werden und folglich die Institutionen der Notfallversorgung entlastet werden. Im weiteren Projektverlauf ist zu untersuchen, was die Einsatzindikationen bei den 1480 (41 %) Einsätzen mit einer Nachalarmierung von Rettungsmitteln sind und wie die Einschätzung der Leitstelle verbessert werden kann.

An Irish National Diabetes in Pregnancy Audit: aiming for best outcomes for women with diabetes

AIMS

The purpose of this study was to identify the number of pregnancies affected by pre-gestational diabetes in the Republic of Ireland; to report on pregnancy outcomes and to identify areas for improvement in care delivery and clinical outcomes.

METHODS

Healthcare professionals caring for women with pre-gestational diabetes during pregnancy were invited to participate in this retrospective study. Data pertaining to 185 pregnancies in women attending 15 antenatal centres nationally were collected and analysed. Included pregnancies had an estimated date of delivery between 1 January and 31 December 2015.

RESULTS

The cohort consisted of 122 (65.9%) women with Type 1 diabetes and 56 (30.3%) women with Type 2 diabetes. The remaining 7 (3.8%) pregnancies were to women with maturity-onset diabetes of the young (MODY) (n = 6) and post-transplant diabetes (n = 1). Overall women were poorly prepared for pregnancy and lapses in specific areas of service delivery including pre-pregnancy care and retinal screening were identified. The majority of pregnancies 156 (84.3%) resulted in a live birth. A total of 103 (65.5%) women had a caesarean delivery and 58 (36.9%) infants were large for gestational age.

CONCLUSIONS

This audit identifies clear areas for improvement in delivery of care for women with diabetes in the Republic of Ireland before and during pregnancy.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Seagrass habitat in Tarawa Lagoon, Kiribati: Service benefits and links to national priority issues

This paper presents a review around seagrass habitat in Tarawa Lagoon, Kiribati and explores the links between seagrass occurrence and the national priority issues of climate change, urban development, human health, nearshore fisheries, threatened species, ocean policy, research capacity and awareness. The contribution of healthy seagrass habitats to many aspects of these national issues is often overlooked and there is need to establish the knowledge gaps and priority actions that can enable mitigation of issues that impact on valuable seagrass resources and their management. Research data on seagrass habitats in Kiribati, and the wider Pacific Island region, is limited and this hinders informed decisions at local, national and regional levels. We present a comprehensive review on seagrass within a national context to aid prioritisation and uptake of information for resource owners, and wider stakeholders, in Kiribati while acknowledging local expertise. The paper highlights data and knowledge gaps that if addressed, will provide information useful to Kiribati nationals, communities and government stakeholders. Recommendations for actions that fill these gaps and build understanding of seagrass resources in Kiribati are provided.

Mushroom productivity trends in relation to tree growth and climate across different European forest biomes

Although it is logical to think that mycorrhizal mushroom production should be somehow related to the growth of the trees from which the fungi obtain carbohydrates, little is known about how mushroom yield patterns are related to tree performance. In this study, we delved into the understanding of the relationships between aboveground fungal productivity, tree radial growth patterns and climatic conditions across three latitudinally different bioclimatic regions encompassing Mediterranean, temperate and boreal forest ecosystems in Europe. For this purpose, we used a large assemblage of long-term data of weekly or biweekly mushroom yield monitoring in Spain, Switzerland and Finland. We analysed the relationships between annual mushroom yield (considering both biomass and number of sporocarps per unit area), tree ring features (tree ring, earlywood and latewood widths), and meteorological conditions (i.e. precipitation and temperature of summer and autumn) from different study sites and forest ecosystems, using both standard and partial correlations. Moreover, we fitted predictive models to estimate mushroom yield from mycorrhizal and saprotrophic fungal guilds based on climatic and dendrochronological variables. Significant synchronies between mushroom yield and climatic and dendrochronological variables were mostly found in drier Mediterranean sites, while few or no significant correlations were found in the boreal and temperate regions. We observed positive correlations between latewood growth and mycorrhizal mushroom biomass only in some Mediterranean sites, this relationship being mainly mediated by summer and autumn precipitation. Under more water-limited conditions, both the seasonal wood production and the mushroom yield are more sensitive to precipitation events, resulting in higher synchrony between both variables. This comparative study across diverse European forest biomes and types provides new insights into the relationship between mushroom productivity, tree growth and weather conditions.

Subjective emotional responses to IAPS pictures in patients with borderline personality disorder, cluster-C personality disorders, and non-patients

According to Linehan (1993), emotion dysregulation is a central feature of borderline personality disorder (BPD). We hypothesized that patients with BPD are emotionally hyperresponsive. For BPD treatment, it is important to evaluate this hypothesis, because, if it is supported, therapeutic interventions could be designed to help patients to better manage hyperemotional reactions. We investigated the subjective reactions (in terms of valence and arousal) of patients with BPD to visual emotional stimuli of the International Affective Picture System (IAPS). We hypothesized that, compared to patients with Cluster-C personality disorders and non-patients, BPD patients would show higher scores on the arousal dimension and higher negative scores on the valence dimension when rating IAPS pictures with varying degrees of arousal and valence. Ratings of valence and arousal for 40 IAPS pictures were collected from 39 borderline personality disorder (BPD), 36 patients diagnosed with Cluster-C personality disorders (PD), and a group of 226 non-patients. Contrary to expectations, BPD patients did not differ from the non-patients. This indicates that their self-report scores do not reflect hypersensitivity. We found that patients with BPD showed lower scores on arousal than Cluster-C PD patients. The scores on valence suggested that Cluster-C PD patients also experienced more positive emotions than BPD patients.

In vivo modeling of human neuron dynamics and Down syndrome

Harnessing the potential of human stem cells for modeling the physiology and diseases of cortical circuitry requires monitoring cellular dynamics in vivo. We show that human induced pluripotent stem cell (iPSC)-derived cortical neurons transplanted into the adult mouse cortex consistently organized into large (up to ~100 mm³) vascularized neuron-glia territories with complex cytoarchitecture. Longitudinal imaging of >4000 grafted developing human neurons revealed that neuronal arbors refined via branch-specific retraction; human synaptic networks substantially restructured over 4 months, with balanced rates of synapse formation and elimination; and oscillatory population activity mirrored the patterns of fetal neural networks. Lastly, we found increased synaptic stability and reduced oscillations in transplants from two individuals with Down syndrome, demonstrating the potential of in vivo imaging in human tissue grafts for patient-specific modeling of cortical development, physiology, and pathogenesis.

Catalytic abatement of CO species from incomplete combustion of solid fuels used in domestic cooking

This study reveals a first time approach to catalytic based interventions primarily on indoor air pollution emanating from commercial and household solid fuel burning in a region in Nigeria. An intensive survey of the temperatures at different locations in the common stoves used for cooking was conducted so as to ascertain temperatures suitable for catalyst efficiency and stability. Furthermore, cobalt and iron based catalysts were prepared using ultra stable Y type zeolite as supports. The synthesized catalysts were characterized for its physico-chemical properties. The catalytic efficiency of the supported catalysts was tested using simulated exhaust gases in a fix bed reactor. The study further explored real time testing of the catalyzed ceramic monolith using two different wood species. First, the best catalyst in terms of simulated exhaust testing was selected. Consequently, a small layer of zeolite Y was deposited at 3% of the monolith weight to enhance the subsequent adhesion of the best catalyst powder to the structured monolith. Then to catalyze the zeolite Y wash-coated monolith with the cobalt precursor, the dip coating technique was used. From the results, the average values of temperatures observed from the surveyed cook stoves using wood and plant residue as fuel were confirmed to be in the range of 203–425 °C which is considered suitable for catalysts activity. The Co/ZY catalyst showed approximately 100% CO conversion (T₁₀₀) at 250 °C for initial CO concentration of 1000 ppm, making it the most effective, while T₁₀₀ was increased to 275 °C and 325 °C for Fe/ZY and Co-Fe/ZY catalyst respectively at an exhaust residence time of 20000 h⁻¹. The catalytic converter in real time testing for CO abatement performed well for both wood species. Only minor differences have been noticed.

The use of a novel adhesive tissue patch as an aid to anastomotic healing

Introduction One of the most feared complications of colorectal surgery is anastomotic leak. Numerous techniques have been studied in the hope of decreasing leakage. This study was designed to assess the handling characteristics of a novel adhesive tissue patch (TissuePatch™; Tissuemed, Leeds, UK) applied to colorectal anastomoses in a pilot study. This was with a view to assessing its potential role in aiding anastomotic healing in subsequent trials. Methods A patch was applied to colorectal anastomoses after the surgeon had completed the anastomosis and prior to abdominal closure. Handling characteristics and patient outcomes were recorded prospectively. Results Nine patients were recruited before the study was prematurely terminated. In one patient, the patch fell off and in another patient, the surgeon omitted to apply it. Six patients had significant postoperative problems (1 confirmed leak necessitating return to theatre and excision anastomosis, 3 suspicious of leak on computed tomography delaying discharge, 2 perianastomotic collections). One patient had an uneventful recovery. Conclusions Although the handling characteristics of this novel tissue patch were deemed satisfactory, it appears that wrapping a colorectal anastomosis with an adhesive hydrophilic patch has significant deleterious effects on anastomotic healing. This could be a consequence of the creation of a microenvironment between the patch and the anastomosis that impairs healing. Further research is required to better understand the mechanisms involved. At present, the use of such patches on colorectal anastomoses should be discouraged outside the confines of a well monitored trial.

Filopodyan: An open-source pipeline for the analysis of filopodia

Filopodia have important sensory and mechanical roles in motile cells. The recruitment of actin regulators, such as ENA/VASP proteins, to sites of protrusion underlies diverse molecular mechanisms of filopodia formation and extension. We developed Filopodyan (filopodia dynamics analysis) in Fiji and R to measure fluorescence in filopodia and at their tips and bases concurrently with their morphological and dynamic properties. Filopodyan supports high-throughput phenotype characterization as well as detailed interactive editing of filopodia reconstructions through an intuitive graphical user interface. Our highly customizable pipeline is widely applicable, capable of detecting filopodia in four different cell types in vitro and in vivo. We use Filopodyan to quantify the recruitment of ENA and VASP preceding filopodia formation in neuronal growth cones, and uncover a molecular heterogeneity whereby different filopodia display markedly different responses to changes in the accumulation of ENA and VASP fluorescence in their tips over time.

Reflective Metasurfaces for Incoherent Light To Bring Computer Graphics Tricks to Optical Systems

The normal mapping technique is widely used in computer graphics to visualize three-dimensional (3D) objects displayed on a flat screen. Taking advantage of optical properties of metasurfaces, which provide a highly efficient approach for manipulation of incident light wavefront, we have designed a metasurface to implement diffuse reflection and used the concept of normal mapping to control its scattering properties. As a proof of principle, we have fabricated and characterized a flat diffuse metasurface imitating lighting and shading effects of a 3D cube. The 3D image is displayed directly on the illuminated metasurface and it is brighter than a standard white paper by up to 2.4 times. The designed structure performs equally well under coherent and incoherent illumination. The normal mapping approach based on metasurfaces can complement traditional optical engineering methods of surface profiling and gradient refractive index engineering in the design of 3D security features, high-performance planar optical diffusers, novel optical elements, and displays.

Directional Emission from Dielectric Leaky-Wave Nanoantennas

An important source of innovation in nanophotonics is the idea to scale down known radio wave technologies to the optical regime. One thoroughly investigated example of this approach are metallic nanoantennas which employ plasmonic resonances to couple localized emitters to selected far-field modes. While metals can be treated as perfect conductors in the microwave regime, their response becomes Drude-like at optical frequencies. Thus, plasmonic nanoantennas are inherently lossy. Moreover, their resonant nature requires precise control of the antenna geometry. A promising way to circumvent these problems is the use of broadband nanoantennas made from low-loss dielectric materials. Here, we report on highly directional emission from hybrid dielectric leaky-wave nanoantennas made of Hafnium dioxide nanostructures deposited on a glass substrate. Colloidal semiconductor quantum dots deposited in the nanoantenna feed gap serve as a local light source. The emission patterns of hybrid nanoantennas with different sizes are measured by Fourier imaging. We find for all antenna sizes a highly directional emission, underlining the broadband operation of our design.

Development and function of human cerebral cortex neural networks from pluripotent stem cells in vitro

A key aspect of nervous system development, including that of the cerebral cortex, is the formation of higher-order neural networks. Developing neural networks undergo several phases with distinct activity patterns in vivo, which are thought to prune and fine-tune network connectivity. We report here that human pluripotent stem cell (hPSC)-derived cerebral cortex neurons form large-scale networks that reflect those found in the developing cerebral cortex in vivo. Synchronised oscillatory networks develop in a highly stereotyped pattern over several weeks in culture. An initial phase of increasing frequency of oscillations is followed by a phase of decreasing frequency, before giving rise to non-synchronous, ordered activity patterns. hPSC-derived cortical neural networks are excitatory, driven by activation of AMPA- and NMDA-type glutamate receptors, and can undergo NMDA-receptor-mediated plasticity. Investigating single neuron connectivity within PSC-derived cultures, using rabies-based trans-synaptic tracing, we found two broad classes of neuronal connectivity: most neurons have small numbers (<10) of presynaptic inputs, whereas a small set of hub-like neurons have large numbers of synaptic connections (>40). These data demonstrate that the formation of hPSC-derived cortical networks mimics in vivo cortical network development and function, demonstrating the utility of in vitro systems for mechanistic studies of human forebrain neural network biology.

Summary: Human PSC-derived cerebral cortex neurons form large-scale functional networks that change over time and mimic those found in the developing cerebral cortex in vivo.

Functional profiling and distribution of the forest soil bacterial communities along the soil mycorrhizosphere continuum

An ectomycorrhiza is a multitrophic association between a tree root, an ectomycorrhizal fungus, free-living fungi and the associated bacterial communities. Enzymatic activities of ectomycorrhizal root tips are therefore result of the contribution from different partners of the symbiotic organ. However, the functional potential of the fungus-associated bacterial communities remains unknown. In this study, a collection of 80 bacterial strains randomly selected and isolated from a soil-ectomycorrhiza continuum (oak-Scleroderma citrinum ectomycorrhizas, the ectomycorrhizosphere and the surrounding bulk soil) were characterized. All the bacterial isolates were identified by partial 16S rRNA gene sequences as members of the genera Burkholderia, Collimonas, Dyella, Mesorhizobium, Pseudomonas, Rhizobium and Sphingomonas. The bacterial strains were then assayed for β-xylosidase, β-glucosidase, N-acetyl-hexosaminidase, β-glucuronidase, cellobiohydrolase, phosphomonoesterase, leucine-aminopeptidase and laccase activities, chitin solubilization and auxin production. Using these bioassays, we demonstrated significant differences in the functional distribution of the bacterial communities living in the different compartments of the soil-ectomycorrhiza continuum. The surrounding bulk soil was significantly enriched in bacterial isolates capable of hydrolysing cellobiose and N-acetylglucosamine. In contrast, the ectomycorrhizosphere appeared significantly enriched in bacterial isolates capable of hydrolysing glucopyranoside and chitin. Notably, chitinase and laccase activities were found only in bacterial isolates belonging to the Collimonas and Pseudomonas genera. Overall, the results suggest that the ectomycorrhizal fungi favour specific bacterial communities with contrasting functional characteristics from the surrounding soil.

Transgenic mouse models enabling photolabeling of individual neurons in vivo

One of the biggest tasks in neuroscience is to explain activity patterns of individual neurons during behavior by their cellular characteristics and their connectivity within the neuronal network. To greatly facilitate linking in vivo experiments with a more detailed molecular or physiological analysis in vitro, we have generated and characterized genetically modified mice expressing photoactivatable GFP (PA-GFP) that allow conditional photolabeling of individual neurons. Repeated photolabeling at the soma reveals basic morphological features due to diffusion of activated PA-GFP into the dendrites. Neurons photolabeled in vivo can be re-identified in acute brain slices and targeted for electrophysiological recordings. We demonstrate the advantages of PA-GFP expressing mice by the correlation of in vivo firing rates of individual neurons with their expression levels of the immediate early gene c-fos. Generally, the mouse models described in this study enable the combination of various analytical approaches to characterize living cells, also beyond the neurosciences.

Drought and air warming affects abundance and exoenzyme profiles of Cenococcum geophilum associated with Quercus robur, Q. petraea and Q. pubescens

The present study aimed to elucidate the influence of drought and elevated temperature on relative abundance and functioning of the ectomycorrhizal fungus Cenococcum geophilum on three oak species differing in adaptation to a warm and dry climate. The experiment QUERCO comprised three Quercus species (Q. robur, Q. petraea, Q. pubescens) grown for 3 years under four treatments: elevated air temperature, drought, a combination of the two, and control. Fine root samples were analysed for relative abundance and potential extracellular enzyme activities of ectomycorrhizae of C. geophilum, a fungal species known to be drought resistant. The relative abundance of C. geophilum on the roots of the oak species was significantly increased by temperature, decreased by drought, but unchanged in the combined treatment compared to the control. Although the extent of treatment effects differed among oak species, no significant influence of tree species on relative abundance of C. geophilum was detected. Exoenzyme activities of C. geophilum on Q. robur and Q. petraea (but not Q. pubescens) significantly increased in the combined treatment, but for all oak species were reduced under drought and air warming alone compared to the control. There was a significant negative correlation between abundance of C. geophilum and its leucine aminopeptidase activity. As this enzyme is not frequent among ectomycorrhizal fungi, this emphasises the functional importance of C. geophilum in the ectomycorrhizal community. Our results indicate that increased temperature and drought will influence the relative abundance and enzyme activity of C. geophilum. However, both the Quercus species and C. geophilum tolerated warming and strong drought.

Induction of immediate early genes in the mouse auditory cortex after auditory cued fear conditioning to complex sounds

Immediate early genes (IEGs) are widely used as markers to delineate neuronal circuits because they show fast and transient expression induced by various behavioral paradigms. In this study, we investigated the expression of the IEGs c-fos and Arc in the auditory cortex of the mouse after auditory cued fear conditioning using quantitative polymerase chain reaction and microarray analysis. To test for the specificity of the IEG induction, we included several control groups that allowed us to test for factors other than associative learning to sounds that could lead to an induction of IEGs. We found that both c-fos and Arc showed strong and robust induction after auditory fear conditioning. However, we also observed increased expression of both genes in any control paradigm that involved shocks, even when no sounds were presented. Using mRNA microarrays and comparing the effect of the various behavioral paradigms on mRNA expression levels, we did not find genes being selectively upregulated in the auditory fear conditioned group. In summary, our results indicate that the use of IEGs to identify neuronal circuits involved specifically in processing of sound cues in the fear conditioning paradigm can be limited by the effects of the aversive unconditional stimulus and that activity levels in a particular primary sensory cortical area can be strongly influenced by stimuli mediated by other modalities.

Adverse effect of noise in the operating theatre on surgical-site infection

Background

The aim of this pilot study was to evaluate the noise level in an operating theatre as a possible surrogate marker for intraoperative behaviour, and to detect any correlation between sound level and subsequent surgical-site infection (SSI).

Methods

The sound level was measured during 35 elective open abdominal procedures. The noise intensity was registered digitally in decibels (dB) every second. A standard questionnaire was used to evaluate the behaviour of the surgical team during the operation. The primary outcome parameter was the SSI rate within 30 days of surgery.

Results

The overall rate of SSI was six of 35 (17 per cent). Demographic parameters and duration of operation were not significantly different between patients with, or without SSI. The median sound level (43·5 (range 26·0–60·0) versus 25·0 (25·0–60·0) dB; P = 0·040) and median level above baseline (10·7 (0·6–33·3) versus 0·6 (0·5–10·8); P = 0·001) were significantly higher for patients who developed a SSI. The sound level was at least 4 dB above the median in 22·5 per cent of the peaks in patients with SSI compared with 10·7 per cent in those without (P = 0·029). Talking about non-surgery-related topics was associated with a significantly higher sound level (P = 0·024).

Conclusion

Intraoperative noise volume was associated with SSI. This may be due to a lack of concentration, or a stressful environment, and may therefore represent a surrogate parameter by which to assess the behaviour of a surgical team.

[Knee cartilage lesions and occupational load. Results of an arthroscopic study]

AIM

Numerous epidemiological studies have suggested a relationship between knee osteoarthritis and occupational load or, respectively, a kneeling or squatting position at work. Cartilage breakdown was clearly identified as the main mechanism of the osteoarthritic process. This arthroscopic study was aimed to evaluate the relationship between frequency and grade of knee cartilage damage compared with occupational load. It was hypothesised that heavy work conditions cause higher cartilage degeneration in diverse age groups. Furthermore, it was suggested that kneeling or squatting work positions (analogous to the BK 2112) produce more severe cartilage damage or other distributions thereof compared with patients in low knee-loading professions.

METHODS

A total of 1199 patients with knee pain (history of 3 months or more) underwent arthroscopic operations. Cartilage lesions were classified according to the ICRS (International Cartilage Repair Society) protocol. The grading of joint degeneration was quantified by using the WOAKS (whole organ arthroscopic knee score). Patients were divided into 5 age groups (24-39-51-64-75 years) by analysis of cluster centres.

RESULTS

In 80.6% (n = 1086) the preoperative radiography suggested signs of a knee osteoarthritis. There was a range from grade I to grade III osteoarthritis according to the Kellgren-Lawrence score. Older female patients had knee osteoarthritis significantly (p = 0.027) more frequently. The grade of osteoarthritis correlated significantly with the patients' age (p > 0.001). The mean WOAKS was 16.6 +/- 13.7 points. There was a continuous increase of WOAKS from 8.2 +/- 5.1 in 24-year-old patients to 24.2 +/- 16.3 points in 75-year-old patients (p < 0.001). In about half of the cases cartilage lesions within the patella and trochlea were evaluated. Most frequently we recorded cartilage lesions within the mean bearing zone of the medial femoral condyle (96.2%) and the medial tibia (57.7)%. Only about a third of our patients suffered from cartilage lesions within the mean bearing zone of the lateral condyle and tibia. The frequency of cartilage lesions and the severity of the lesions grade was significantly less within the non-loaded margin of the surfaces. In 45 knees (3.8%) we found intraarticular osteophytes located: medial (n = 9) and lateral (n = 3) patella margin, intracondylar notch (n = 12), medial tibia (n = 9) and lateral margin of the lateral tibia (n = 4), lateral femoral condyle at the intersection to the lateral trochlea margin (n = 3). The occurrence of osteophytes correlated with the patients' age and the radiological grade of the osteoarthritis. There were no differences with respect to the profession within the age groups. In the non-adjusted WOAKS, patients with hard knee-loading work had a WOAKS of 16.8 +/- 13.9 points and patients with soft work a score of 17.2 +/- 14.3 points (p = 0.583). Differences in the frequency of cartilage distributions within the judged regions of the knee with respect to professional burden were also not evaluated. The same held for the frequency of intraarticular osteophytes.

CONCLUSION

Despite there is a known relation between occupational load and knee osteoarthritis no relation to cartilage degeneration was found in our arthroscopic investigation. For better understanding of work-related knee osteoarthritis prospective studies are needed urgently.