GSK3ß Inhibition by Phosphorylation at Ser389 Controls Neuroinflammation.

The inhibition of Glycogen Synthase Kinase 3 ß (GSK3ß) by Ser9 phosphorylation affects many physiological processes, including the immune response. However, the consequences of GSK3ß inhibition by alternative Ser389 phosphorylation remain poorly characterized. Here we have examined neuroinflammation in GSK3ß Ser389 knock-in (KI) mice, in which the phosphorylation of Ser389 GSK3ß is impaired. The number of activated microglia/infiltrated macrophages, astrocytes, and infiltrated neutrophils was significantly higher in these animals compared to C57BL/6J wild-type (WT) counterparts, which suggests that the failure to inactivate GSK3ß by Ser389 phosphorylation results in sustained low-grade neuroinflammation. Moreover, glial cell activation and brain infiltration of immune cells in response to lipopolysaccharide (LPS) failed in GSK3ß Ser389 KI mice. Such effects were brain-specific, as peripheral immunity was not similarly affected. Additionally, phosphorylation of the IkB kinase complex (IKK) in response to LPS failed in GSK3ß Ser389 KI mice, while STAT3 phosphorylation was fully conserved, suggesting that the NF-κB signaling pathway is specifically affected by this GSK3ß regulatory pathway. Overall, our findings indicate that GSK3ß inactivation by Ser389 phosphorylation controls the brain inflammatory response, raising the need to evaluate its role in the progression of neuroinflammatory pathologies.

Intranasal Administration of Undifferentiated Oligodendrocyte Lineage Cells as a Potential Approach to Deliver Oligodendrocyte Precursor Cells into Brain.

Oligodendrocyte precursor cell (OPC) migration is a mechanism involved in remyelination; these cells migrate from niches in the adult CNS. However, age and disease reduce the pool of OPCs; as a result, the remyelination capacity of the CNS decreases over time. Several experimental studies have introduced OPCs to the brain via direct injection or intrathecal administration. In this study, we used the nose-to brain pathway to deliver oligodendrocyte lineage cells (human oligodendroglioma (HOG) cells), which behave similarly to OPCs in vitro. To this end, we administered GFP-labelled HOG cells intranasally to experimental animals, which were subsequently euthanised at 30 or 60 days. Our results show that the intranasal route is a viable route to the CNS and that HOG cells administered intranasally migrate preferentially to niches of OPCs (clusters created during embryonic development and adult life). Our study provides evidence, albeit limited, that HOG cells either form clusters or adhere to clusters of OPCs in the brains of experimental animals.

A CMOS Low Pass Filter for SoC Lock-in-Based Measurement Devices.

This paper presents a fully integrated Gm-C low pass filter (LPF) based on a current steering Gm reduction-tuning technique, specifically designed to operate as the output stage of a SoC lock-in amplifier. To validate this proposal, a first-order and a second-order single-ended topology were integrated into a 1.8 V to 0.18 µm CMOS (Complementary Metal-Oxide-Semiconductor) process, showing experimentally a tuneable cutoff frequency that spanned five orders of magnitude, from tens of mHz to kHz, with a constant current consumption (below 3 µA/pole), compact size (<0.0140 mm2/pole), and a dynamic range better than 70 dB. Compared to state-of-the-art solutions, the proposed approach exhibited very competitive performances while simultaneously fully satisfying the demanding requirements of on-chip portable measurement systems in terms of highly efficient area and power. This is of special relevance, taking into account the current trend towards multichannel instruments to process sensor arrays, as the total area and power consumption will be proportional to the number of channels.

A 0.18 µm CMOS LDO Regulator for an On-Chip Sensor Array Impedance Measurement System.

This paper presents a fully integrated 0.18 μm CMOS Low-Dropout (LDO) Voltage Regulator specifically designed to meet the stringent requirements of a battery-operated impedance spectrometry multichannel CMOS micro-instrument. The proposed LDO provides a regulated 1.8 V voltage from a 3.6 V to 1.94 V battery voltage over a −40 °C to 100 °C temperature range, with a compact topology (<0.10 mm² area) and a constant quiescent current of only 7.45 μA with 99.985% current efficiency, achieving remarkable state-of-art Figures of Merit (FoMs) for the regulating⁻transient performance. Experimental measurements validate its suitability for the target application, paving the way towards the future achievement of a truly portable System on Chip (SoC) platform for impedance sensors.

A CMOS Self-Contained Quadrature Signal Generator for SoC Impedance Spectroscopy.

This paper presents a low-power fully integrated quadrature signal generator for system-on-chip (SoC) impedance spectroscopy applications. It has been designed in a 0.18 μm-1.8 V CMOS technology as a self-contained oscillator, without the need for an external reference clock. The frequency can be digitally tuned from 10 to 345 kHz with 12-bit accuracy and a relative mean error below 1.7%, thus supporting a wide range of impedance sensing applications. The proposal is experimentally validated in two impedance spectrometry examples, achieving good magnitude and phase recovery results compared to the results obtained using a commercial LCR-meter. Besides the wide frequency tuning range, the proposed programmable oscillator features a total power consumption lower than 0.77 mW and an active area of 0.129 mm², thus constituting a highly suitable choice as stimulation module for instrument-on-a-chip devices.

A Compact Energy Harvesting System for Outdoor Wireless Sensor Nodes Based on a Low-Cost In Situ Photovoltaic Panel Characterization-Modelling Unit.

This paper presents a low-cost high-efficiency solar energy harvesting system to power outdoor wireless sensor nodes. It is based on a Voltage Open Circuit (VOC) algorithm that estimates the open-circuit voltage by means of a multilayer perceptron neural network model trained using local experimental characterization data, which are acquired through a novel low cost characterization system incorporated into the deployed node. Both units-characterization and modelling-are controlled by the same low-cost microcontroller, providing a complete solution which can be understood as a virtual pilot cell, with identical characteristics to those of the specific small solar cell installed on the sensor node, that besides allows an easy adaptation to changes in the actual environmental conditions, panel aging, etc. Experimental comparison to a classical pilot panel based VOC algorithm show better efficiency under the same tested conditions.

A Wearable Wireless Sensor Network for Indoor Smart Environment Monitoring in Safety Applications.

This paper presents the implementation of a wearable wireless sensor network aimed at monitoring harmful gases in industrial environments. The proposed solution is based on a customized wearable sensor node using a low-power low-rate wireless personal area network (LR-WPAN) communications protocol, which as a first approach measures CO2 concentration, and employs different low power strategies for appropriate energy handling which is essential to achieving long battery life. These wearables nodes are connected to a deployed static network and a web-based application allows data storage, remote control and monitoring of the complete network. Therefore, a complete and versatile remote web application with a locally implemented decision-making system is accomplished, which allows early detection of hazardous situations for exposed workers.

A High Performance LIA-Based Interface for Battery Powered Sensing Devices.

This paper proposes a battery-compatible electronic interface based on a general purpose lock-in amplifier (LIA) capable of recovering input signals up to the MHz range. The core is a novel ASIC fabricated in 1.8 V 0.18 µm CMOS technology, which contains a dual-phase analog lock-in amplifier consisting of carefully designed building blocks to allow configurability over a wide frequency range while maintaining low power consumption. It operates using square input signals. Hence, for battery-operated microcontrolled systems, where square reference and exciting signals can be generated by the embedded microcontroller, the system benefits from intrinsic advantages such as simplicity, versatility and reduction in power and size. Experimental results confirm the signal recovery capability with signal-to-noise power ratios down to -39 dB with relative errors below 0.07% up to 1 MHz. Furthermore, the system has been successfully tested measuring the response of a microcantilever-based resonant sensor, achieving similar results with better power-bandwidth trade-off compared to other LIAs based on commercial off-the-shelf (COTS) components and commercial LIA equipment.

Using Fluorescent GAP Indicators to Monitor ER Ca2.

The endoplasmic reticulum (ER) is the main reservoir of Ca2+ of the cell. Accurate and quantitative measuring of Ca2+ dynamics within the lumen of the ER has been challenging. In the last decade a few genetically encoded Ca2+ indicators have been developed, including a family of fluorescent Ca2+ indicators, dubbed GFP-Aequorin Proteins (GAPs). They are based on the fusion of two jellyfish proteins, the green fluorescent protein (GFP) and the Ca2+-binding protein aequorin. GAP Ca2+ indicators exhibit a combination of several features: they are excitation ratiometric indicators, with reciprocal changes in the fluorescence excited at 405 and 470 nm, which is advantageous for imaging experiments; they exhibit a Hill coefficient of 1, which facilitates the calibration of the fluorescent signal into Ca2+ concentrations; they are insensible to variations in the Mg2+ concentrations or pH variations (in the 6.5-8.5 range); and, due to the lack of mammalian homologues, these proteins have a favorable expression in transgenic animals. A low Ca2+ affinity version of GAP, GAP3 (KD ≅ 489 µM), has been engineered to conform with the estimated [Ca2+] in the ER. GAP3 targeted to the lumen of the ER (erGAP3) can be utilized for imaging intraluminal Ca2+. The ratiometric measurements provide a quantitative method to assess accurate [Ca2+]ER, both dynamically and at rest. In addition, erGAP3 can be combined with synthetic cytosolic Ca2+ indicators to simultaneously monitor ER and cytosolic Ca2+. Here, we provide detailed methods to assess erGAP3 expression and to perform Ca2+ imaging, either restricted to the ER lumen, or simultaneously in the ER and the cytosol. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Detection of erGAP3 in the ER by immunofluorescence Basic Protocol 2: Monitoring ER Ca2+ Basic Protocol 3: Monitoring ER- and cytosolic-Ca2+ Support Protocol: Generation of a stable cell line expressing erGAP3.

In Vitro Effects of Methylprednisolone over Oligodendroglial Cells: Foresight to Future Cell Therapies.

The implantation of oligodendrocyte precursor cells may be a useful therapeutic strategy for targeting remyelination. However, it is yet to be established how these cells behave after implantation and whether they retain the capacity to proliferate or differentiate into myelin-forming oligodendrocytes. One essential issue is the creation of administration protocols and determining which factors need to be well established. There is controversy around whether these cells may be implanted simultaneously with corticosteroid treatment, which is widely used in many clinical situations. This study assesses the influence of corticosteroids on the capacity for proliferation and differentiation and the survival of human oligodendroglioma cells. Our findings show that corticosteroids reduce the capacity of these cells to proliferate and to differentiate into oligodendrocytes and decrease cell survival. Thus, their effect does not favour remyelination; this is consistent with the results of studies with rodent cells. In conclusion, protocols for the administration of oligodendrocyte lineage cells with the aim of repopulating oligodendroglial niches or repairing demyelinated axons should not include corticosteroids, given the evidence that the effects of these drugs may undermine the objectives of cell transplantation.

Hippocampal subfield abnormalities and biomarkers of pathologic brain changes: from SARS-CoV-2 acute infection to post-COVID syndrome.

BACKGROUND: Cognitive deficits are among the main disabling symptoms in COVID-19 patients and post-COVID syndrome (PCS). Within brain regions, the hippocampus, a key region for cognition, has shown vulnerability to SARS-CoV-2 infection. Therefore, in vivo detailed evaluation of hippocampal changes in PCS patients, validated on post-mortem samples of COVID-19 patients at the acute phase, would shed light into the relationship between COVID-19 and cognition. METHODS: Hippocampal subfields volume, microstructure, and perfusion were evaluated in 84 PCS patients and compared to 33 controls. Associations with blood biomarkers, including glial fibrillary acidic protein (GFAP), myelin oligodendrocyte glycoprotein (MOG), eotaxin-1 (CCL11) and neurofilament light chain (NfL) were evaluated. Besides, biomarker immunodetection in seven hippocampal necropsies of patients at the acute phase were contrasted against eight controls. FINDINGS: In vivo analyses revealed that hippocampal grey matter atrophy is accompanied by altered microstructural integrity, hypoperfusion, and functional connectivity changes in PCS patients. Hippocampal structural and functional alterations were related to cognitive dysfunction, particularly attention and memory. GFAP, MOG, CCL11 and NfL biomarkers revealed alterations in PCS, and showed associations with hippocampal volume changes, in selective hippocampal subfields. Moreover, post mortem histology showed the presence of increased GFAP and CCL11 and reduced MOG concentrations in the hippocampus in post-mortem samples at the acute phase. INTERPRETATION: The current results evidenced that PCS patients with cognitive sequalae present brain alterations related to cognitive dysfunction, accompanied by a cascade of pathological alterations in blood biomarkers, indicating axonal damage, astrocyte alterations, neuronal injury, and myelin changes that are already present from the acute phase. FUNDING: Nominative Grant FIBHCSC 2020 COVID-19. Department of Health, Community of Madrid. Instituto de Salud Carlos III through the project INT20/00079, co-funded by European Regional Development Fund "A way to make Europe" (JAMG). Instituto de Salud Carlos III (ISCIII) through Sara Borrell postdoctoral fellowship Grant No. CD22/00043) and co-funded by the European Union (MDC). Instituto de Salud Carlos III through a predoctoral contract (FI20/000145) (co-funded by European Regional Development Fund "A way to make Europe") (MVS). Fundación para el Conocimiento Madri+d through the project G63-HEALTHSTARPLUS-HSP4 (JAMG, SOM).

The Integration of Cell Therapy and Biomaterials as Treatment Strategies for Remyelination.

Multiple sclerosis (MS) is a chronic degenerative autoimmune disease of the central nervous system that causes inflammation, demyelinating lesions, and axonal damage and is associated with a high rate of early-onset disability. Disease-modifying therapies are used to mitigate the inflammatory process in MS but do not promote regeneration or remyelination; cell therapy may play an important role in these processes, modulating inflammation and promoting the repopulation of oligodendrocytes, which are responsible for myelin repair. The development of genetic engineering has led to the emergence of stable, biocompatible biomaterials that may promote a favorable environment for exogenous cells. This review summarizes the available evidence about the effects of transplantation of different types of stem cells reported in studies with several animal models of MS and clinical trials in human patients. We also address the advantages of combining cell therapy with biomaterials.

Nose-to-Brain: The Next Step for Stem Cell and Biomaterial Therapy in Neurological Disorders.

Neurological disorders are a leading cause of morbidity worldwide, giving rise to a growing need to develop treatments to revert their symptoms. This review highlights the great potential of recent advances in cell therapy for the treatment of neurological disorders. Through the administration of pluripotent or stem cells, this novel therapy may promote neuroprotection, neuroplasticity, and neuroregeneration in lesion areas. The review also addresses the administration of these therapeutic molecules by the intranasal route, a promising, non-conventional route that allows for direct access to the central nervous system without crossing the blood-brain barrier, avoiding potential adverse reactions and enabling the administration of large quantities of therapeutic molecules to the brain. Finally, we focus on the need to use biomaterials, which play an important role as nutrient carriers, scaffolds, and immune modulators in the administration of non-autologous cells. Little research has been conducted into the integration of biomaterials alongside intranasally administered cell therapy, a highly promising approach for the treatment of neurological disorders.

A programmable plug & play sensor interface for WSN applications.

Cost reduction in wireless sensor networks (WSN) becomes a priority when extending their application to fields where a great number of sensors is needed, such as habitat monitoring, precision agriculture or diffuse greenhouse emission measurement. In these cases, the use of smart sensors is expensive, consequently requiring the use of low-cost sensors. The solution to convert such generic low-cost sensors into intelligent ones leads to the implementation of a versatile system with enhanced processing and storage capabilities to attain a plug and play electronic interface able to adapt to all the sensors used. This paper focuses on this issue and presents a low-voltage plug & play reprogrammable interface capable of adapting to different sensor types and achieving an optimum reading performance for every sensor. The proposed interface, which includes both electronic and software elements so that it can be easily integrated in WSN nodes, is described and experimental test results to validate its performance are given.

An FPGA-Based Machine Learning Tool for In-Situ Food Quality Tracking Using Sensor Fusion.

The continuous development of more accurate and selective bio- and chemo-sensors has led to a growing use of sensor arrays in different fields, such as health monitoring, cell culture analysis, bio-signals processing, or food quality tracking. The analysis and information extraction from the amount of data provided by these sensor arrays is possible based on Machine Learning techniques applied to sensor fusion. However, most of these computing solutions are implemented on costly and bulky computers, limiting its use in in-situ scenarios outside complex laboratory facilities. This work presents the application of machine learning techniques in food quality assessment using a single Field Programmable Gate Array (FPGA) chip. The characteristics of low-cost, low power consumption as well as low-size allow the application of the proposed solution even in space constrained places, as in food manufacturing chains. As an example, the proposed system is tested on an e-nose developed for beef classification and microbial population prediction.

Regulation of GSK3ß by Ser389 Phosphorylation During Neural Development.

GSK3ß is a constitutively active kinase that promotes cell death, which requires strict regulatory mechanisms. Although Akt-mediated phosphorylation at Ser9 is the default mechanism to inactivate GSK3ß, phosphorylation of GSK3ß at Ser389 by p38 MAPK has emerged as an alternative inhibitory pathway that provides cell protection and repair in response to DNA damage. Phosphorylation of Ser389 GSK3ß has been detected in adult brain, where it has been related to neuronal survival and behavior. However, the use of this pathway to regulate GSK3ß in the neonatal developing brain is unknown. In this study, we show that phosphorylation of GSK3ß at Ser389 in the brain is developmentally regulated, with the highest levels corresponding to the first 2 weeks of age. Moreover, we found that the phosphorylation of GSK3ß at Ser389 is the preferential mechanism for inactivating brain GSK3ß in 2-week-old mice. Importantly, we show that phospho-Ser389 GSK3ß expression is predominant in neuronal cell cultures from neonatal brain relative to other cell populations. However, phospho-Ser389 GSK3ß is triggered by DNA double-strand breaks in all developing neural cell types examined. Thus, the phosphorylation of GSK3ß on Ser389 could be a central regulatory mechanism to restrain GSK3ß during neurogenesis early in life.

Dissociation of neonatal and adult mice brain for simultaneous analysis of microglia, astrocytes and infiltrating lymphocytes by flow cytometry.

The technical difficulty to isolate microglia, astrocytes and infiltrating immune cells from mouse brain is nowadays a limiting factor in the study of neuroinflammation. Brain isolation requirements are cell-type and animal-age dependent, but current brain dissociation procedures are poorly standardized. This lack of comprehensive studies hampers the selection of optimized methodologies. Thus, we present here a comparative analysis of dissociation methods and Percoll-based separation to identify the most efficient procedure for the combined isolation of healthy microglia, astrocytes and infiltrated leukocytes; distinguishing neonatal and adult mouse brain. Gentle mechanical dissociation and DNase I incubation was supplemented with papain or collagenase II. Dispase II digestion was also used alone or in combination. In addition, cell separation efficiency of 30 % and 30-70 % Percoll gradients was compared. In these experiments, cell yield and integrity of freshly dissociated cells was measured by flow cytometry. We found that papain digestion in combination with dispase II followed by 30 % Percoll separation is the most balanced method to obtain a mixture of microglia, astrocytes and infiltrated immune cells; while addition of dispase II was not an advantage for neonatal brain. These dissociation conditions allowed flow cytometry detection of a slight glial activation triggered by sublethal LPS injection. In conclusion, the enzymes and Percoll density gradients tested here affected differently resting microglia, activated microglia/macrophages, astrocytes and infiltrated lymphocytes. Also, newborn and adult brain showed contrasting reactions to digestion. Our study highlights the strength of flow cytometry for the simultaneous analysis of neuroimmune cell populations once extraction is optimized.

Digitally programmable analogue circuits for sensor conditioning systems.

This work presents two current-mode integrated circuits designed for sensor signal preprocessing in embedded systems. The proposed circuits have been designed to provide good signal transfer and fulfill their function, while minimizing the load effects due to building complex conditioning architectures. The processing architecture based on the proposed building blocks can be reconfigured through digital programmability. Thus, sensor useful range can be expanded, changes in the sensor operation can be compensated for and furthermore, undesirable effects such as device mismatching and undesired physical magnitudes sensor sensibilities are reduced. The circuits were integrated using a 0.35 µm standard CMOS process. Experimental measurements, load effects and a study of two different tuning strategies are presented. From these results, system performance is tested in an application which entails extending the linear range of a magneto-resistive sensor. Circuit area, average power consumption and programmability features allow these circuits to be included in embedded sensing systems as a part of the analogue conditioning components.