Autocrine, paracrine and necrotic NMDA receptor signalling in mouse pancreatic neuroendocrine tumour cells.

N-Methyl-d-aspartate receptor (NMDAR) activation is implicated in the malignant progression of many cancer types, as previously shown by the growth-inhibitory effects of NMDAR antagonists. NMDAR-mediated calcium influx and its downstream signalling depend critically, however, on the dynamics of membrane potential and ambient glutamate concentration, which are poorly characterized in cancer cells. Here, we have used low-noise whole-cell patch-clamp recording to investigate the electrophysiology of glutamate signalling in pancreatic neuroendocrine tumour (PanNET) cells derived from a genetically-engineered mouse model (GEMM) of PanNET, in which NMDAR signalling is known to promote cancer progression. Activating NMDARs caused excitation and intracellular calcium elevation, and intracellular perfusion with physiological levels of glutamate led to VGLUT-dependent autocrine NMDAR activation. Necrotic cells, which are often present in rapidly-growing tumours, were shown to release endogenous cytoplasmic glutamate, and necrosis induced by mechanical rupture of the plasma membrane produced intense NMDAR activation in nearby cells. Computational modelling, based on these results, predicts that NMDARs in cancer cells can be strongly activated in the tumour microenvironment by both autocrine glutamate release and necrosis

Virtual edge illumination and one dimensional beam tracking for absorption, refraction, and scattering retrieval

We propose two different approaches to retrieve x-ray absorption, refraction, and scattering signals using a one dimensional scan and a high resolution detector. The first method can be easily implemented in existing procedures developed for edge illumination to retrieve absorption and refraction signals, giving comparable image quality while reducing exposure time and delivered dose. The second method tracks the variations of the beam intensity profile on the detector through a multi-Gaussian interpolation, allowing the additional retrieval of the scattering signal

Novel coronavirus disease-2019 (COVID-19) in people with rheumatic disease: Epidemiology and outcomes

There is concern that people with rheumatic disease, often treated with immunosuppressive or immunomodulatory medication, may be at an increased risk of poor outcomes of novel coronavirus disease-2019 (COVID-19). However, hyperinflammation is a major cause of morbidity and mortality in COVID-19 and treatment with glucocorticoids has been shown to improve outcomes in patients with severe COVID-19. Therefore, uncertainty exists about continuing or withholding immune therapies with the risk of infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review covers the current knowledge with respect to the risk of infection and outcomes and risk factors for poor outcomes in patients with rheumatic disease. We also discuss data from other immune-mediated diseases and its relevance to patients with rheumatic disease. In addition, we cover the limitations of the research efforts to date and how the current knowledge translates into practice guidance. Finally, we discuss our vision of the future research agenda

Global research collaboration in a pandemic-challenges and opportunities: the COVID-19 Global Rheumatology Alliance

PURPOSE OF REVIEW: This review discusses the coronavirus disease-2019 (COVID-19) Global Rheumatology Alliance (GRA), the reason for its formation, the challenges with running the registry, and future opportunities for global collaborative research in rheumatology. RECENT FINDINGS: The GRA has been successful in collecting and publishing a large volume of case data on patients with rheumatic disease with COVID-19. In addition, the GRA has published reviews, opinion pieces, and patient-directed summaries of research to further assist in disseminating timely and accurate information about COVID-19 in rheumatic diseases. There have been numerous challenges in the journey but they have been addressed through a collaborative problem-solving approach. SUMMARY: The initial objectives of the GRA to describe the outcomes in patients with rheumatic disease who developed COVID-19 have been achieved. There has been extensive use of the data in the clinic and also to try and understand the mechanisms of disease and opportunities for drug repurposing. There remain numerous important areas for research which the GRA will continue to pursue as the pandemic evolves

Intrinsic Cornu Ammonis Area 1 Theta-Nested Gamma Oscillations Induced by Optogenetic Theta Frequency Stimulation.

UNLABELLED: Gamma oscillations (30-120 Hz) are thought to be important for various cognitive functions, including perception and working memory, and disruption of these oscillations has been implicated in brain disorders, such as schizophrenia and Alzheimer's disease. The cornu ammonis area 1 (CA1) of the hippocampus receives gamma frequency inputs from upstream regions (cornu ammonis area 3 and medial entorhinal cortex) and generates itself a faster gamma oscillation. The exact nature and origin of the intrinsic CA1 gamma oscillation is still under debate. Here, we expressed channel rhodopsin-2 under the CaMKIIα promoter in mice and prepared hippocampal slices to produce a model of intrinsic CA1 gamma oscillations. Sinusoidal optical stimulation of CA1 at theta frequency was found to induce robust theta-nested gamma oscillations with a temporal and spatial profile similar to CA1 gamma in vivo The results suggest the presence of a single gamma rhythm generator with a frequency range of 65-75 Hz at 32 °C. Pharmacological analysis found that the oscillations depended on both AMPA and GABAA receptors. Cell-attached and whole-cell recordings revealed that excitatory neuron firing slightly preceded interneuron firing within each gamma cycle, suggesting that this intrinsic CA1 gamma oscillation is generated with a pyramidal-interneuron circuit mechanism. SIGNIFICANCE STATEMENT: This study demonstrates that the cornu ammonis area 1 (CA1) is capable of generating intrinsic gamma oscillations in response to theta input. This gamma generator is independent of activity in the upstream regions, highlighting that CA1 can produce its own gamma oscillation in addition to inheriting activity from the upstream regions. This supports the theory that gamma oscillations predominantly function to achieve local synchrony, and that a local gamma generated in each area conducts the signal to the downstream region.J.L.B. is support by a Biotechnology and Biological Sciences Research Council CASE Studentship in collaboration with Eli Lilly and Company, and P.R.F.M. is supported by a CAPES Science without Borders Cambridge Scholarship.This is the final version of the article. It first appeared from the Society for Neuroscience via http://dx.doi.org/10.1523/JNEUROSCI.3150-15.201

Kv4.2 channel activity controls intrinsic firing dynamics of arcuate kisspeptin neurons.

KEY POINTS: Neurons in the hypothalamus of the brain which secrete the peptide kisspeptin are important regulators of reproduction, and normal reproductive development. Electrical activity, in the form of action potentials, or spikes, leads to secretion of peptides and neurotransmitters, influencing the activity of downstream neurons; in kisspeptin neurons, this activity is highly irregular, but the mechanism of this is not known. In this study, we show that irregularity depends on the presence of a particular type of potassium ion channel in the membrane, which opens transiently in response to electrical excitation. The results contribute to understanding how kisspeptin neurons generate and time their membrane potential spikes, and how reliable this process is. Improved understanding of the activity of kisspeptin neurons, and how it shapes their secretion of peptides, is expected to lead to better treatment for reproductive dysfunction and disorders of reproductive development. ABSTRACT: Kisspeptin neurons in the hypothalamus are critically involved in reproductive function, via their effect on GnRH neuron activity and consequent gonadotropin release. Kisspeptin neurons show an intrinsic irregularity of firing, but the mechanism of this remains unclear. To address this, we carried out targeted whole-cell patch-clamp recordings of kisspeptin neurons in the arcuate nucleus (Kiss1Arc ), in brain slices isolated from adult male Kiss-Cre:tdTomato mice. Cells fired irregularly in response to constant current stimuli, with a wide range of spike time variability, and prominent subthreshold voltage fluctuations. In voltage clamp, both a persistent sodium (NaP) current and a fast transient (A-type) potassium current were apparent, activating at potentials just below the threshold for spiking. These currents have also previously been described in irregular-spiking cortical interneurons, in which the A-type current, mediated by Kv4 channels, interacts with NaP current to generate complex dynamics of the membrane potential, and irregular firing. In Kiss1Arc neurons, A-type current was blocked by phrixotoxin, a specific blocker of Kv4.2/4.3 channels, and consistent expression of Kv4.2 transcripts was detected by single-cell RT-PCR. In addition, firing irregularity was correlated to the density of A-type current in the membrane. Using conductance injection, we demonstrated that adding Kv4-like potassium conductance (gKv4 ) to a cell produces a striking increase in firing irregularity, and excitability is reduced, while subtracting gKv4 has the opposite effects. Thus, we propose that Kv4 interacting dynamically with NaP is a key determinant of the irregular firing behaviour of Kiss1Arc neurons, shaping their physiological function in gonadotropin release

Improved sensitivity at synchrotrons using edge illumination X-ray phase-contrast imaging

The application of the X-ray phase-contrast ‘edge illumination’ principle to the highly coherent beams available at synchrotron radiation facilities is presented here. We show that, in this configuration, the technique allows achieving unprecedented angular sensitivity, of the order of few nanoradians. The results are obtained at beamlines of two different synchrotron radiation facilities, using various experimental conditions. In particular, different detectors and X-ray energies (12 keV and 85 keV) were employed, proving the flexibility of the method and the broad range of conditions over which it can be applied. Furthermore, the quantitative separation of absorption and refraction information, and the application of the edge illumination principle in combination with computed tomography, are also demonstrated. Thanks to its extremely high phase sensitivity and its flexible applicability, this technique will both improve the image quality achievable with X-ray phase contrast imaging and allow tackling areas of application which remain unexplored until now

X-Ray Phase-Contrast Imaging with Nanoradian Angular Resolution

We present a new quantitative x-ray phase-contrast imaging method based on the edge illumination principle, which allows achieving unprecedented nanoradian sensitivity. The extremely high angular resolution is demonstrated theoretically and through experimental images obtained at two different synchrotron radiation facilities. The results, achieved at both very high and very low x-ray energies, show that this highly sensitive technique can be efficiently exploited over a very broad range of experimental conditions. This method can open the way to new, previously inaccessible scientific applications in various fields including biology, medicine and materials science

X–ray absorption, phase and dark–field tomography through a beam tracking approach

We present a development of the beam–tracking approach that allows its implementation in computed tomography. One absorbing mask placed before the sample and a high resolution detector are used to track variations in the beam intensity distribution caused by the sample. Absorption, refraction, and dark–field are retrieved through a multi–Gaussian interpolation of the beam. Standard filtered back projection is used to reconstruct three dimensional maps of the real and imaginary part of the refractive index, and of the dark–field signal. While the method is here demonstrated using synchrotron radiation, its low coherence requirements suggest a possible implementation with laboratory sources