Effet des glucocorticoïdes sur la capacité de dilution du rein chez un rongeur désertique : Gerbillus campestris

International audienc

Towards a Machine Learning-Based Digital Twin for Non-Invasive Human Bio-Signal Fusion

Human bio-signal fusion is considered a critical technological solution that needs to be advanced to enable modern and secure digital health and well-being applications in the metaverse. To support such efforts, we propose a new data-driven digital twin (DT) system to fuse three human physiological bio-signals: heart rate (HR), breathing rate (BR), and blood oxygen saturation level (SpO2). To accomplish this goal, we design a computer vision technology based on the non-invasive photoplethysmography (PPG) technique to extract raw time-series bio-signal data from facial video frames. Then, we implement machine learning (ML) technology to model and measure the bio-signals. We accurately demonstrate the digital twin capability in the modelling and measuring of three human bio-signals, HR, BR, and SpO2, and achieve strong performance compared to the ground-truth values. This research sets the foundation and the path forward for realizing a holistic human health and well-being DT model for real-world medical applications

ATP as a mediator of macula densa cell signalling

Within each nephro-vascular unit, the tubule returns to the vicinity of its own glomerulus. At this site, there are specialised tubular cells, the macula densa cells, which sense changes in tubular fluid composition and transmit information to the glomerular arterioles resulting in alterations in glomerular filtration rate and blood flow. Work over the last few years has characterised the mechanisms that lead to the detection of changes in luminal sodium chloride and osmolality by the macula densa cells. These cells are true “sensor cells” since intracellular ion concentrations and membrane potential reflect the level of luminal sodium chloride concentration. An unresolved question has been the nature of the signalling molecule(s) released by the macula densa cells. Currently, there is evidence that macula densa cells produce nitric oxide via neuronal nitric oxide synthase (nNOS) and prostaglandin E2 (PGE2) through cyclooxygenase 2 (COX 2)-microsomal prostaglandin E synthase (mPGES). However, both of these signalling molecules play a role in modulating or regulating the macula-tubuloglomerular feedback system. Direct macula densa signalling appears to involve the release of ATP across the basolateral membrane through a maxi-anion channel in response to an increase in luminal sodium chloride concentration. ATP that is released by macula densa cells may directly activate P2 receptors on adjacent mesangial cells and afferent arteriolar smooth muscle cells, or the ATP may be converted to adenosine. However, the critical step in signalling would appear to be the regulated release of ATP across the basolateral membrane of macula densa cells