Intravenous prostaglandin E1 (alprostadil) bolus in ductus arteriosus-dependent CHD: valid or absolutely contraindicated?

The use of prostaglandin E1 is well documented in ductus arteriosus-dependent CHD or in neonatal pulmonary pathologies that cause severe pulmonary hypertension. The intravenous infusion is well established in loading infusion and maintenance with an onset of action of 30 minutes until 2 hours or even more. Our aim is to report three patients with pulmonary atresia that presented hypercyanotic spell due to a ductal spasm during cardiac catheterisation in whom the administration of a bolus of alprostadil reversed the spasm and increased pulmonary flow, immediately stabilising the condition of the patients allowing subsequent successful stent placement with no serious complications or sequelae after the administration of the bolus. More studies are needed to make a recommendation regarding the use of alprostadil in bolus in cases where the ductal spasm might jeopardise the life of the patient.

SARS-CoV-2 Viroporin E Induces Ca2+ Release and Neuron Cell Death in Primary Cultures of Rat Hippocampal Cells Aged In Vitro.

The COVID-19 pandemic was caused by infection with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which may lead to serious respiratory, vascular and neurological dysfunctions. The SARS-CoV-2 envelope protein (E protein) is a structural viroporin able to form ion channels in cell membranes, which is critical for viral replication. However, its effects in primary neurons have not been addressed. Here we used fluorescence microscopy and calcium imaging to study SARS-CoV-2 viroporin E localization and the effects on neuron damage and intracellular Ca2+ homeostasis in a model of rat hippocampal neurons aged in vitro. We found that the E protein quickly enters hippocampal neurons and colocalizes with the endoplasmic reticulum (ER) in both short-term (6-8 days in vitro, DIV) and long-term (20-22 DIV) cultures resembling young and aged neurons, respectively. Strikingly, E protein treatment induces apoptosis in aged neurons but not in young neurons. The E protein induces variable increases in cytosolic Ca2+ concentration in hippocampal neurons. Ca2+ responses to the E protein are due to Ca2+ release from intracellular stores at the ER. Moreover, E protein-induced Ca2+ release is very small in young neurons and increases dramatically in aged neurons, consistent with the enhanced Ca2+ store content in aged neurons. We conclude that the SARS-CoV-2 E protein quickly translocates to ER endomembranes of rat hippocampal neurons where it releases Ca2+, probably acting like a viroporin, thus producing Ca2+ store depletion and neuron apoptosis in aged neurons and likely contributing to neurological damage in COVID-19 patients.

Toll-like receptors in neuroinflammation, neurodegeneration, and alcohol-induced brain damage.

Toll-like receptors (TLRs) or pattern recognition receptors respond to pathogen-associated molecular patterns (PAMPs) or internal damage-associated molecular patterns (DAMPs). TLRs are integral membrane proteins with both extracellular leucine-rich and cytoplasmic domains that initiate downstream signaling through kinases by activating transcription factors like AP-1 and NF-κB, which lead to the release of various inflammatory cytokines and immune modulators. In the central nervous system, different TLRs are expressed mainly in microglia and astroglial cells, although some TLRs are also expressed in oligodendroglia and neurons. Activation of TLRs triggers signaling cascades by the host as a defense mechanism against invaders to repair damaged tissue. However, overactivation of TLRs disrupts the sustained immune homeostasis-induced production of pro-inflammatory molecules, such as cytokines, miRNAs, and inflammatory components of extracellular vesicles. These inflammatory mediators can, in turn, induce neuroinflammation, and neural tissue damage associated with many neurodegenerative diseases. This review discusses the critical role of TLRs response in Alzheimer's disease, Parkinson's disease, ischemic stroke, amyotrophic lateral sclerosis, and alcohol-induced brain damage and neurodegeneration.

Pilot phase experience of the International Quality Improvement Collaborative catheterization registry.

OBJECTIVES: To describe the development of a quality collaborative for congenital cardiac catheterization centers in low and middle-income countries (LMICs) including pilot study data and a novel procedural efficacy measure. BACKGROUND: Absence of congenital cardiac catheterization registries in LMICs led to the development of the International Quality Improvement Collaborative Congenital Heart Disease Catheterization Registry (IQIC-CHDCR). As a foundation for this initiative, the IQIC is a collaboration of pediatric cardiac surgical programs from LMICs. Participation in IQIC has been associated with improved patient outcomes. METHODS: A web-based registry was designed through a collaborative process. A pilot study was conducted from October through December 2017 at seven existing IQIC sites. Demographic, hemodynamic, and adverse event data were obtained and a novel tool to assess procedural efficacy was applied to five specific procedures. Procedural efficacy was categorized using ideal, adequate, and inadequate. RESULTS: A total of 429 cases were entered. Twenty-five adverse events were reported. The five procedures for which procedural efficacy was measured represented 48% of cases (n = 208) and 71% had complete data for analysis (n = 146). Procedure efficacy was ideal most frequently in patent ductus arteriosus (95%) and atrial septal defect (90%) device closure, and inadequate most frequently in coarctation procedures (100%), and aortic and pulmonary valvuloplasties (50%). CONCLUSIONS: The IQIC-CHDCR has designed a feasible collaborative to capture catheterization data in LMICs. The novel tool for procedural efficacy will provide valuable means to identify areas for quality improvement. This pilot study and lessons learned culminated in the full launch of the IQIC-CHDCR.

Marine Heterocyclic Compounds That Modulate Intracellular Calcium Signals: Chemistry and Synthesis Approaches.

Intracellular Ca2+ plays a pivotal role in the control of a large series of cell functions in all types of cells, from neurotransmitter release and muscle contraction to gene expression, cell proliferation and cell death. Ca2+ is transported through specific channels and transporters in the plasma membrane and subcellular organelles such as the endoplasmic reticulum and mitochondria. Therefore, dysregulation of intracellular Ca2+ homeostasis may lead to cell dysfunction and disease. Accordingly, chemical compounds from natural origin and/or synthesis targeting directly or indirectly these channels and proteins may be of interest for the treatment of cell dysfunction and disease. In this review, we show an overview of a group of marine drugs that, from the structural point of view, contain one or various heterocyclic units in their core structure, and from the biological side, they have a direct influence on the transport of calcium in the cell. The marine compounds covered in this review are divided into three groups, which correspond with their direct biological activity, such as compounds with a direct influence in the calcium channel, compounds with a direct effect on the cytoskeleton and drugs with an effect on cancer cell proliferation. For each target, we describe its bioactive properties and synthetic approaches. The wide variety of chemical structures compiled in this review and their significant medical properties may attract the attention of many different researchers.

[Degree of association between healthcare indicators and poverty measures in Chile over the period 1992-2017]. / Salud y Pobreza en Chile de Post-Transición: ¿Qué nos dicen los indicadores de pobreza sobre la salud de la población?

BACKGROUND: More than half of the worlds's population is deprived of essential healthcare services. In consideration of this, the World Health Organization introduced the concept of Social Determinants of Health to improve the awareness of this problem. AIM: To investigate and compare the pertinence of monetary and multidimensional measures of poverty as indirect measures of health status. MATERIAL AND METHODS: Three indices were used: the Historic Multidimensional Poverty Index (HMPI), calculated using Alkire-Foster method; health deprivations associated with the HMPI; and households in conditions of monetary poverty. The poverty identification outcomes for the three indices mentioned were all estimated using data from the Chilean national socioeconomic survey CASEN for the period 1992-2017. RESULTS: First, independently of how poverty is measured (monetarily or multidimensionally), the degree to which households living in poverty conditions are simultaneously suffering health deprivations steadily decreased during the period 1992-2017. Second, the association between multidimensional poverty and health deprivations is stronger than the association between health deprivations and monetary poverty. CONCLUSIONS: Poverty calculated on the basis of income alone is an inadequate predictor of health deprivations; multidimensional poverty performs better. However, poverty and health indicators have become progressively less associated. Therefore, it becomes necessary either to adapt the health indicators included in Multidimensional Poverty Index to the current health challenges or to implement a Multidimensional Health Deprivation Index, with a view to improving the integration of health within the current social policy framework.

Remodeling of Intracellular Ca2+ Homeostasis in Rat Hippocampal Neurons Aged In Vitro.

Aging is often associated with a cognitive decline and a susceptibility to neuronal damage. It is also the most important risk factor for neurodegenerative disorders, particularly Alzheimer's disease (AD). AD is related to an excess of neurotoxic oligomers of amyloid ß peptide (Aßo); however, the molecular mechanisms are still highly controversial. Intracellular Ca2+ homeostasis plays an important role in the control of neuronal activity, including neurotransmitter release, synaptic plasticity, and memory storage, as well as neuron cell death. Recent evidence indicates that long-term cultures of rat hippocampal neurons, resembling aged neurons, undergo cell death after treatment with Aßo, whereas short-term cultures, resembling young neurons, do not. These in vitro changes are associated with the remodeling of intracellular Ca2+ homeostasis with aging, thus providing a simplistic model for investigating Ca2+ remodeling in aging. In vitro aged neurons show increased resting cytosolic Ca2+ concentration, enhanced Ca2+ store content, and Ca2+ release from the endoplasmic reticulum (ER). Ca2+ transfer from the endoplasmic reticulum (ER) to mitochondria is also enhanced. Aged neurons also show decreased store-operated Ca2+ entry (SOCE), a Ca2+ entry pathway related to memory storage. At the molecular level, in vitro remodeling is associated with changes in the expression of Ca2+ channels resembling in vivo aging, including changes in N-methyl-D-aspartate NMDA receptor and inositol 1,4,5-trisphosphate (IP3) receptor isoforms, increased expression of the mitochondrial calcium uniporter (MCU), and decreased expression of Orai1/Stim1, the molecular players involved in SOCE. Additionally, Aßo treatment exacerbates most of the changes observed in aged neurons and enhances susceptibility to cell death. Conversely, the solely effect of Aßo in young neurons is to increase ER-mitochondria colocalization and enhance Ca2+ transfer from ER to mitochondria without inducing neuronal damage. We propose that cultured rat hippocampal neurons may be a useful model to investigate Ca2+ remodeling in aging and in age-related neurodegenerative disorders.

The Eighth ECS Workshop on "Calcium Signaling in Aging and Neurodegenerative Diseases".

The European Calcium Society (ECS) is very glad to present the realization of a special issue of the International Journal of Molecular Sciences (IJMS) related to the eighth ECS workshop organized this year around the theme of "Calcium Signaling in Aging and Neurodegenerative Diseases" [...].

Calcium remodeling in colorectal cancer.

Colorectal cancer (CRC) is the third most frequent form of cancer and the fourth leading cause of cancer-related death in the world. Basic and clinical data indicate that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) may prevent colon cancer but mechanisms remain unknown. Aspirin metabolite salicylate and other NSAIDs may inhibit tumor cell growth acting on store-operated Ca2+ entry (SOCE), suggesting an important role for this pathway in CRC. Consistently, SOCE is emerging as a novel player in different forms of cancer, including CRC. SOCE and store-operated currents (SOCs) are dramatically enhanced in CRC while Ca2+ stores are partially empty in CRC cells. These features may contribute to CRC hallmarks including enhanced cell proliferation, migration, invasion and survival. At the molecular level, enhanced SOCE and depleted stores are mediated by overexpression of Orai1, Stromal interaction protein 1 (STIM1) and Transient receptor protein channel 1 (TRPC1) and downregulation of STIM2. In normal colonic cells, SOCE is mediated by Ca2+-release activated Ca2+ channels made of STIM1, STIM2 and Orai1. In CRC cells, SOCE is mediated by different store-operated currents (SOCs) driven by STIM1, Orai1 and TRPC1. Loss of STIM2 contributes to depletion of Ca2+ stores and enhanced resistance to cell death in CRC cells. Thus, SOCE is a novel key player in CRC and inhibition by salicylate and other NSAIDs may contribute to explain chemoprevention activity. SUMMARY: Colorectal cancer (CRC) is the third most frequent form of cancer worldwide. Recent evidence suggests that intracellular Ca2+ remodeling may contribute to cancer hallmarks. In addition, aspirin and other NSAIDs might prevent CRC acting on remodeled Ca2+ entry pathways. In this review, we will briefly describe 1) the players involved in intracellular Ca2+ homeostasis with a particular emphasis on the mechanisms involved in SOCE activation and inactivation, 2) the evidence that aspirin metabolite salicylate and other NSAIDs inhibits tumor cell growth acting on SOCE, 3) evidences on the remodeling of intracellular Ca2+ in cancer with a particular emphasis in SOCE, 4) the remodeling of SOCE and Ca2+ store content in CRC and, finally, 5) the molecular basis of Ca2+ remodeling in CRC. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.

Mitochondrial control of store-operated Ca2+ channels in cancer: Pharmacological implications.

Intracellular Ca2+ is a pleiotropic second messenger involved in control of different cell and physiological functions including long-term processes such as cell proliferation, migration and survival. Agonist-induced Ca2+ entry in most cells, especially in non-excitable cells including epithelial cells, is mediated by store-operated Ca2+ entry (SOCE), a Ca2+ entry pathway activated by agonist-induced release of Ca2+ from intracellular stores in the endoplasmic reticulum (ER). This pathway is modulated also by mitochondria which, acting as Ca2+ sinks, take up Ca2+, thus limiting Ca2+-dependent inactivation of Ca2+-release activated Ca2+ channels (CRAC). Compelling evidence shows that SOCE is upregulated in a large variety of cancer cells and this change contribute to cancer hallmarks. Mechanisms for enhanced SOCE include changes in expression of members of the Orai, Stromal interaction molecule (STIM) and canonical transient receptor potential channel (TRPc) gene families. Tumor cell mitochondria may contribute to SOCE upregulation in cancer as well. Molecular players involved in enhancing mitochondrial Ca2+ uptake are upregulated in tumor cells whereas negative modulators are repressed. Furthermore, mitochondrial potential, the driving force for mitochondrial Ca2+ uptake, is enhanced in tumor cells due to the Warburg effect. Finally, SOCE in tumor cells may be sustained further by the gain of function of non-selective TRPC channels permeable to Na+ that favour Ca2+ exit from mitochondria in exchange for Na+, thus limiting Ca2+-dependent inactivation of Orai1 channels. Therefore, tumor cell mitochondria may efficiently contribute to enhance and sustain SOCE in cancer. Interestingly, this effect could be counterbalanced by selected non-steroidal anti-inflammatory drugs (NSAIDs) reported to prevent colorectal cancer and other forms of cancer.

In vitro aging promotes endoplasmic reticulum (ER)-mitochondria Ca2+ cross talk and loss of store-operated Ca2+ entry (SOCE) in rat hippocampal neurons.

Aging is associated to cognitive decline and susceptibility to neuron death, two processes related recently to subcellular Ca2+ homeostasis. Memory storage relies on mushroom spines stability that depends on store-operated Ca2+ entry (SOCE). In addition, Ca2+ transfer from endoplasmic reticulum (ER) to mitochondria sustains energy production but mitochondrial Ca2+ overload promotes apoptosis. We have addressed whether SOCE and ER-mitochondria Ca2+ transfer are influenced by culture time in long-term cultures of rat hippocampal neurons, a model of neuronal aging. We found that short-term cultured neurons show large SOCE, low Ca2+ store content and no functional coupling between ER and mitochondria. In contrast, in long-term cultures reflecting aging neurons, SOCE is essentially lost, Stim1 and Orai1 are downregulated, Ca2+ stores become overloaded, Ca2+ release is enhanced, expression of the mitochondrial Ca2+ uniporter (MCU) increases and most Ca2+ released from the ER is transferred to mitochondria. These results suggest that neuronal aging is associated to increased ER-mitochondrial cross talking and loss of SOCE. This subcellular Ca2+ remodeling might contribute to cognitive decline and susceptibility to neuron cell death in the elderly.

Aging and amyloid ß oligomers enhance TLR4 expression, LPS-induced Ca2+ responses, and neuron cell death in cultured rat hippocampal neurons.

BACKGROUND: Toll-like receptors (TLRs) are transmembrane pattern-recognition receptors of the innate immune system recognizing diverse pathogen-derived and tissue damage-related ligands. It has been suggested that TLR signaling contributes to the pathogenesis of age-related, neurodegenerative diseases, including Alzheimer's disease (AD). AD is associated to oligomers of the amyloid ß peptide (Aßo) that cause intracellular Ca2+ dishomeostasis and neuron cell death in rat hippocampal neurons. Here we assessed the interplay between inflammation and Aßo in long-term cultures of rat hippocampal neurons, an in vitro model of neuron aging and/or senescence. METHODS: Ca2+ imaging and immunofluorescence against annexin V and TLR4 were applied in short- and long-term cultures of rat hippocampal neurons to test the effects of TLR4-agonist LPS and Aßo on cytosolic [Ca2+] and on apoptosis as well as on expression of TLR4. RESULTS: LPS increases cytosolic [Ca2+] and promotes apoptosis in rat hippocampal neurons in long-term culture considered aged and/or senescent neurons, but not in short-term cultured neurons considered young neurons. TLR4 antagonist CAY10614 prevents both effects. TLR4 expression in rat hippocampal neurons is significantly larger in aged hippocampal cultures. Treatment of aged hippocampal cultures with Aßo increases TLR4 expression and enhances LPS-induced Ca2+ responses and neuron cell death. CONCLUSIONS: Aging and amyloid ß oligomers, the neurotoxin involved in Alzheimer's disease, enhance TLR4 expression as well as LPS-induced Ca2+ responses and neuron cell death in rat hippocampal neurons aged in vitro.

Transcriptomic Analysis of Calcium Remodeling in Colorectal Cancer.

Colorectal cancer (CRC) cells undergo the remodeling of intracellular Ca2+ homeostasis, which contributes to cancer hallmarks such as enhanced proliferation, invasion and survival. Ca2+ remodeling includes critical changes in store-operated Ca2+ entry (SOCE) and Ca2+ store content. Some changes have been investigated at the molecular level. However, since nearly 100 genes are involved in intracellular Ca2+ transport, a comprehensive view of Ca2+ remodeling in CRC is lacking. We have used Next Generation Sequencing (NGS) to investigate differences in expression of 77 selected gene transcripts involved in intracellular Ca2+ transport in CRC. To this end, mRNA from normal human colonic NCM460 cells and human colon cancer HT29 cells was isolated and used as a template for transcriptomic sequencing and expression analysis using Ion Torrent technology. After data transformation and filtering, exploratory analysis revealed that both cell types were well segregated. In addition, differential gene expression using R and bioconductor packages show significant differences in expression of selected voltage-operated Ca2+ channels and store-operated Ca2+ entry players, transient receptor potential (TRP) channels, Ca2+ release channels, Ca2+ pumps, Na⁺/Ca2+ exchanger isoforms and genes involved in mitochondrial Ca2+ transport. These data provide the first comprehensive transcriptomic analysis of Ca2+ remodeling in CRC.

Delphinidin Reduces Glucose Uptake in Mice Jejunal Tissue and Human Intestinal Cells Lines through FFA1/GPR40.

Anthocyanins are pigments with antihyperglycemic properties, and they are potential candidates for developing functional foods for the therapy or prevention of Diabetes mellitus type 2 (DM2). The mechanism of these beneficial effects of anthocyanins are, however, hard to explain, given their very low bioavailability due to poor intestinal absorption. We propose that free fatty acid receptor 1 (FFA1, also named GPR40), is involved in an inhibitory effect of the anthocyanidin delphinidin over intestinal glucose absorption. We show the direct effects of delphinidin on the intestine using jejunum samples from RF/J mice, and the human intestinal cell lines HT-29, Caco-2, and NCM460. By the use of specific pharmacological antagonists, we determined that delphinidin inhibits glucose absorption in both mouse jejunum and a human enterocytic cell line in a FFA1-dependent manner. Delphinidin also affects the function of sodium-glucose cotransporter 1 (SGLT1). Intracellular signaling after FFA1 activation involved cAMP increase and cytosolic Ca2+ oscillations originated from intracellular Ca2+ stores and were followed by store-operated Ca2+ entry. Taken together, our results suggest a new GPR-40 mediated local mechanism of action for delphinidin over intestinal cells that may in part explain its antidiabetic effect. These findings are promising for the search for new prevention and pharmacological treatment strategies for DM2 management.

Remodeling of Calcium Entry Pathways in Cancer.

Ca(2+) entry pathways play important roles in control of many cellular functions, including long-term proliferation, migration and cell death. In recent years, it is becoming increasingly clear that, in some types of tumors, remodeling of Ca(2+) entry pathways could contribute to cancer hallmarks such as excessive proliferation, cell migration and invasion as well as resistance to cell death or survival. In this chapter we briefly review findings related to remodeling of Ca(2+) entry pathways in cancer with emphasis on the mechanisms that contribute to increased store-operated Ca(2+) entry (SOCE) and store-operated currents (SOCs) in colorectal cancer cells. Finally, since SOCE appears critically involved in colon tumorogenesis, the inhibition of SOCE by aspirin and other NSAIDs and its possible contribution to colon cancer chemoprevention is reviewed.

A reciprocal shift in transient receptor potential channel 1 (TRPC1) and stromal interaction molecule 2 (STIM2) contributes to Ca2+ remodeling and cancer hallmarks in colorectal carcinoma cells.

We have investigated the molecular basis of intracellular Ca(2+) handling in human colon carcinoma cells (HT29) versus normal human mucosa cells (NCM460) and its contribution to cancer features. We found that Ca(2+) stores in colon carcinoma cells are partially depleted relative to normal cells. However, resting Ca(2+) levels, agonist-induced Ca(2+) increases, store-operated Ca(2+) entry (SOCE), and store-operated currents (ISOC) are largely enhanced in tumor cells. Enhanced SOCE and depleted Ca(2+) stores correlate with increased cell proliferation, invasion, and survival characteristic of tumor cells. Normal mucosa cells displayed small, inward Ca(2+) release-activated Ca(2+) currents (ICRAC) mediated by ORAI1. In contrast, colon carcinoma cells showed mixed currents composed of enhanced ICRAC plus a nonselective ISOC mediated by TRPC1. Tumor cells display increased expression of TRPC1, ORAI1, ORAI2, ORAI3, and STIM1. In contrast, STIM2 protein was nearly depleted in tumor cells. Silencing data suggest that enhanced ORAI1 and TRPC1 contribute to enhanced SOCE and differential store-operated currents in tumor cells, whereas ORAI2 and -3 are seemingly less important. In addition, STIM2 knockdown decreases SOCE and Ca(2+) store content in normal cells while promoting apoptosis resistance. These data suggest that loss of STIM2 may underlie Ca(2+) store depletion and apoptosis resistance in tumor cells. We conclude that a reciprocal shift in TRPC1 and STIM2 contributes to Ca(2+) remodeling and tumor features in colon cancer.

Susceptibility to excitotoxicity in aged hippocampal cultures and neuroprotection by non-steroidal anti-inflammatory drugs: role of mitochondrial calcium.

Brain damage after insult and cognitive decline are related to excitotoxicity and strongly influenced by aging, yet mechanisms of aging-dependent susceptibility to excitotoxicity are poorly known. Several non-steroidal anti-inflammatory drugs (NSAIDs) may prevent excitotoxicity and cognitive decline in the elderly by an unknown mechanism. Interestingly, after several weeks in vitro, hippocampal neurons display important hallmarks of neuronal aging in vivo. Accordingly, rat hippocampal neurons cultured for several weeks were used to investigate mechanisms of aging-related susceptibility to excitotoxicity and neuroprotection by NSAIDs. We found that NMDA increased cytosolic Ca(2+) concentration in young, mature and aged neurons but only promoted apoptosis in aged neurons. Resting Ca(2+) levels and responses to NMDA increased with time in culture which correlated with changes in expression of NMDA receptor subunits. In addition, NMDA promoted mitochondrial Ca(2+) uptake only in aged cultures. Consistently, specific inhibition of mitochondrial Ca(2+) uptake decreased apoptosis. Finally, we found that a series of NSAIDs depolarized mitochondria and inhibited mitochondrial Ca(2+) overload, thus preventing NMDA-induced apoptosis in aged cultures. We conclude that mitochondrial Ca(2+) uptake is critical for age-related susceptibility to excitotoxicity and neuroprotection by NSAIDs. Rat hippocampal neurons aged in culture were used to investigate mechanisms of age-related susceptibility to excitotoxicity and neuroprotection by non-steroidal anti-inflammatory drugs (NSAIDs). Old neurons display enhanced resting calcium and responses to NMDA along with increased expression of NMDA receptor subunits NR1 and NR2A altogether favoring mitochondrial calcium overload. NSAIDs protect neurons against excitotoxicity acting on mitochondrial calcium uptake. NMDA, N methyl d-aspartate.

Calcium microdomains at the immunological synapse: how ORAI channels, mitochondria and calcium pumps generate local calcium signals for efficient T-cell activation.

Cell polarization enables restriction of signalling into microdomains. Polarization of lymphocytes following formation of a mature immunological synapse (IS) is essential for calcium-dependent T-cell activation. Here, we analyse calcium microdomains at the IS with total internal reflection fluorescence microscopy. We find that the subplasmalemmal calcium signal following IS formation is sufficiently low to prevent calcium-dependent inactivation of ORAI channels. This is achieved by localizing mitochondria close to ORAI channels. Furthermore, we find that plasma membrane calcium ATPases (PMCAs) are re-distributed into areas beneath mitochondria, which prevented PMCA up-modulation and decreased calcium export locally. This nano-scale distribution-only induced following IS formation-maximizes the efficiency of calcium influx through ORAI channels while it decreases calcium clearance by PMCA, resulting in a more sustained NFAT activity and subsequent activation of T cells.

Structural and practical identifiability analysis in bioengineering: a beginner's guide.

Advancements in digital technology have brought modelling to the forefront in many disciplines from healthcare to architecture. Mathematical models, often represented using parametrised sets of ordinary differential equations, can be used to characterise different processes. To infer possible estimates for the unknown parameters, these models are usually calibrated using associated experimental data. Structural and practical identifiability analyses are a key component that should be assessed prior to parameter estimation. This is because identifiability analyses can provide insights as to whether or not a parameter can take on single, multiple, or even infinitely or countably many values which will ultimately have an impact on the reliability of the parameter estimates. Also, identifiability analyses can help to determine whether the data collected are sufficient or of good enough quality to truly estimate the parameters or if more data or even reparameterization of the model is necessary to proceed with the parameter estimation process. Thus, such analyses also provide an important role in terms of model design (structural identifiability analysis) and the collection of experimental data (practical identifiability analysis). Despite the popularity of using data to estimate the values of unknown parameters, structural and practical identifiability analyses of these models are often overlooked. Possible reasons for non-consideration of application of such analyses may be lack of awareness, accessibility, and usability issues, especially for more complicated models and methods of analysis. The aim of this study is to introduce and perform both structural and practical identifiability analyses in an accessible and informative manner via application to well established and commonly accepted bioengineering models. This will help to improve awareness of the importance of this stage of the modelling process and provide bioengineering researchers with an understanding of how to utilise the insights gained from such analyses in future model development.

[Cardiovascular manifestations in pediatric multisystem inflammatory syndrome associated with COVID-19 in a tertiary care pediatric center in Mexico City]. / Alteraciones cardiovasculares en el síndrome inflamatorio multisistémico pediátrico asociado a COVID-19 en un hospital pediátrico de tercer nivel de la Ciudad de México.

Objective: The objective is to expose the cardiovascular alterations in patients diagnosed with pediatric inflammatory multisystem syndrome (PIMS) associated with COVID-19 during the SARS-CoV-2 pandemic, in order to understand the disease, its evolution, and optimal management upon diagnosis. Method: Retrospective, observational, cross-sectional analytical study of patients diagnosed with PIMS according to the criteria of the World Health Organization at the National Institute of Pediatrics, from March 2020 to December 2021. Results: During the study period, 77 patients with PIMS were diagnosed. The results showed correlation between the shock state and alteration of laboratory markers (platelets 144217.29 ± 139321.6 µL [p < 0.001], procalcitonin 27.37 ± 38.37 ng/ml [p = 0.05] and ferritin 1937.87 ± 2562.63 [p < 0.001]). The ventricular function in patients with shock was significantly lower compared to those without shock (49.6 ± 9.1% vs. 58.1 ± 8.4 %; t-Student p < 0.001), as well as injury to the left coronary artery (p = 0.02). There is a correlation between NT-proBNP and ventricular dysfunction (Kruskal-Wallis p = 0.007). Statistical significance was found in the association between death, elevation of inflammatory markers and ventricular dysfunction (p < 0.001). Conclusions: The cardiovascular alterations observed, in order of frequency, were pericardial effusion (25.7%), myocarditis (15%), mild ventricular dysfunction (13.5%) and small coronary aneurysm with predominance of the left coronary artery and the anterior descending one.

Objetivo: Exponer las alteraciones cardiovasculares en los pacientes diagnosticados con síndrome inflamatorio multisistémico pediátrico (PIMS) asociado a COVID-19 durante la pandemia por SARS-CoV-2 con el fin de comprender la enfermedad, su evolución y el manejo óptimo al diagnóstico. Método: Estudio retrospectivo, observacional, transversal y analítico de pacientes con diagnóstico de PIMS de acuerdo con los criterios de la Organización Mundial de la Salud en el Instituto Nacional de Pediatría, de marzo de 2020 a diciembre de 2021. Resultados: Durante el periodo de estudio se diagnosticaron 77 pacientes con PIMS. Los resultados demostraron una correlación entre el estado de choque y la alteración de los marcadores de laboratorio (plaquetas 144217.29 ± 139321.6 µl [p < 0.001], procalcitonina 27.37 ± 38.37 ng/ml [p = 0.05] y ferritina 1937.87 ± 2562.63 [p < 0.001]). La función ventricular en los pacientes con choque se registró significativamente menor en comparación con aquellos sin choque (49.6 ± 9.1 % vs. 58.1 ± 8.4 %; t de Student p < 0.001), así como lesión en la arteria coronaria izquierda (p = 0.02). Existe una correlación entre el NT-proBNP y la disfunción ventricular (Kruskal-Wallis p = 0.007). Se encontró significancia estadística en la asociación entre fallecimiento, elevación de los marcadores inflamatorios y disfunción ventricular (p < 0.001). Conclusiones: Las alteraciones cardiovasculares observadas fueron, en orden de frecuencia, derrame pericárdico (25.7%), miocarditis (15%), disfunción ventricular leve (13.5%) y aneurisma pequeño coronario con predominio de la arteria coronaria izquierda y la descendente anterior.