Pathogenic DPAGT1 variants in limb-girdle congenital myasthenic syndrome (LG-CMS) associated with tubular aggregates and ORAI1 hypoglycosylation.

AIMS: Limb-girdle congenital myasthenic syndrome (LG-CMS) is a genetically heterogeneous disorder characterized by muscle weakness and fatigability. The LG-CMS gene DPAGT1 codes for an essential enzyme of the glycosylation pathway, a posttranslational modification mechanism shaping the structure and function of proteins. In DPAGT1-related LG-CMS, reduced glycosylation of the acetylcholine receptor (AChR) reduces its localization at the neuromuscular junction (NMJ), and results in diminished neuromuscular transmission. LG-CMS patients also show tubular aggregates on muscle biopsy, but the origin and potential contribution of the aggregates to disease development are not understood. Here, we describe two LG-CMS patients with the aim of providing a molecular diagnosis and to shed light on the pathways implicated in tubular aggregate formation. METHODS: Following clinical examination of the patients, we performed next-generation sequencing (NGS) to identify the genetic causes, analysed the biopsies at the histological and ultrastructural levels, investigated the composition of the tubular aggregates, and performed experiments on protein glycosylation. RESULTS: We identified novel pathogenic DPAGT1 variants in both patients, and pyridostigmine treatment quantitatively improved muscle force and function. The tubular aggregates contained proteins of the sarcoplasmic reticulum (SR) and structurally conformed to the aggregates observed in tubular aggregate myopathy (TAM). TAM arises from overactivation of the plasma membrane calcium channel ORAI1, and functional studies on muscle extracts from our LG-CMS patients evidenced abnormal ORAI1 glycosylation. CONCLUSIONS: We expand the genetic variant spectrum of LG-CMS and provide a genotype/phenotype correlation for pathogenic DPAGT1 variants. The discovery of ORAI1 hypoglycosylation in our patients highlights a physiopathological link between LG-CMS and TAM.

Silencing of the Ca2+ Channel ORAI1 Improves the Multi-Systemic Phenotype of Tubular Aggregate Myopathy (TAM) and Stormorken Syndrome (STRMK) in Mice.

Tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK) form a clinical continuum associating progressive muscle weakness with additional multi-systemic anomalies of the bones, skin, spleen, and platelets. TAM/STRMK arises from excessive extracellular Ca2+ entry due to gain-of-function mutations in the Ca2+ sensor STIM1 or the Ca2+ channel ORAI1. Currently, no treatment is available. Here we assessed the therapeutic potential of ORAI1 downregulation to anticipate and reverse disease development in a faithful mouse model carrying the most common TAM/STRMK mutation and recapitulating the main signs of the human disorder. To this aim, we crossed Stim1R304W/+ mice with Orai1+/- mice expressing 50% of ORAI1. Systematic phenotyping of the offspring revealed that the Stim1R304W/+Orai1+/- mice were born with a normalized ratio and showed improved postnatal growth, bone architecture, and partly ameliorated muscle function and structure compared with their Stim1R304W/+ littermates. We also produced AAV particles containing Orai1-specific shRNAs, and intramuscular injections of Stim1R304W/+ mice improved the skeletal muscle contraction and relaxation properties, while muscle histology remained unchanged. Altogether, we provide the proof-of-concept that Orai1 silencing partially prevents the development of the multi-systemic TAM/STRMK phenotype in mice, and we also established an approach to target Orai1 expression in postnatal tissues.

ORAI1 inhibition as an efficient preclinical therapy for tubular aggregate myopathy and Stormorken syndrome.

Tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK) are clinically overlapping disorders characterized by childhood-onset muscle weakness and a variable occurrence of multisystemic signs, including short stature, thrombocytopenia, and hyposplenism. TAM/STRMK is caused by gain-of-function mutations in the Ca2+ sensor STIM1 or the Ca2+ channel ORAI1, both of which regulate Ca2+ homeostasis through the ubiquitous store-operated Ca2+ entry (SOCE) mechanism. Functional experiments in cells have demonstrated that the TAM/STRMK mutations induce SOCE overactivation, resulting in excessive influx of extracellular Ca2+. There is currently no treatment for TAM/STRMK, but SOCE is amenable to manipulation. Here, we crossed Stim1R304W/+ mice harboring the most common TAM/STRMK mutation with Orai1R93W/+ mice carrying an ORAI1 mutation partially obstructing Ca2+ influx. Compared with Stim1R304W/+ littermates, Stim1R304W/+Orai1R93W/+ offspring showed a normalization of bone architecture, spleen histology, and muscle morphology; an increase of thrombocytes; and improved muscle contraction and relaxation kinetics. Accordingly, comparative RNA-Seq detected more than 1,200 dysregulated genes in Stim1R304W/+ muscle and revealed a major restoration of gene expression in Stim1R304W/+Orai1R93W/+ mice. Altogether, we provide physiological, morphological, functional, and molecular data highlighting the therapeutic potential of ORAI1 inhibition to rescue the multisystemic TAM/STRMK signs, and we identified myostatin as a promising biomarker for TAM/STRMK in humans and mice.

Role of surface adsorption and porosity features in the molecular recognition ability of imprinted sol-gels.

Organically modified molecularly imprinted silicas (MIS) for nafcillin recognition were prepared using a simple sol-gel procedure. Molecular recognition of the template was observed by tuning the chemical and structural properties of the MIS. The relative amounts of organically modified alkoxysilane precursors were found to be key in the textural and morphological characteristics of the MIS as well as for developing an imprinting effect in the materials. The recognition properties of the imprinted materials were found to be strongly influenced by the hydrolytic stability of the alkoxysilanes and their inductive effects during sol-gel hydrolysis/condensation stages. The concept was to combine properties of organic groups with those of glass-like materials in order to develop synergetic properties through variations in the composition. Results from batch rebinding experiments as well as from the thorough study of the N(2) adsorption properties and the textural and structural characteristics of the MIS revealed that an imprint effect could be attributed to the presence of the template during the synthesis of MIS.

Molecularly imprinted sol-gels for nafcillin determination in milk-based products.

A study has been made of the analytical application of a nafcillin-imprinted sol-gel to the direct determination of the beta-lactamic antibiotic in spiked milk-based samples using a room temperature phosphorescent flow-through system. The influence of the sample matrix on the transduction and the recognition processes was statistically determined, and results demonstrated that the imprinted sol-gel optosensing system could be effectively applied to real sample analysis. The analytical performance characteristics were as follows: The detection limit results for aqueous and skimmed milk were 5.8 x 10(-6) and 3.3 x 10(-5) mol L(-1), respectively, and a relative standard deviation less than 5% was found for both matrices. Statistical analysis of variance studies have been shown to have no significant effect on different skimmed milk commercial products over the imprinted material recognition. This fact provides an indicator of the ruggedness/robustness of the proposed analytical system and the possibility to use external real matrix calibration. Application of the method to nafcillin analysis in other milk-based samples is outlined.

Aspectes perinatals del nadons prematurs nascuts per pneumònia covid-19 materna greu / Prematuridad por neumonía covid-19 materna grave / Preterm births due to severe maternal covid-19 pneumonia

Fonament. En els mesos de juliol i agost del 2021, coincidint amb l’onada de SARS-CoV-2 a causa de la variantdelta del virus i amb la vacunació poblacional encara incompleta, a l’hospital Vall d’Hebron hi va haver diversosingressos de nounats prematurs a causa de pneumòniagreu per covid-19 materna, en ser aquest un centre dereferència per a gestants amb covid-19 greu. En aquesttreball es recullen les característiques més rellevantsd’aquesta població.Objectiu. Descriure l’experiència amb nounats prematurs acausa de pneumònia greu per SARS-CoV-2 materna.Mètode. Es tracta d’un treball descriptiu que reuneix elscasos atesos a l’Hospital Vall d’Hebron (Barcelona) durantdos mesos, i en mostra les característiques clíniques principals.Resultats. La majoria dels pacients van ser negatius per aSARS-CoV-2 en els aspirats fets durant l’ingrés, no van requerir suport respiratori perllongat ni van presentar patologies importants més enllà de les associades a la prematuritat. Destaca la freqüència de símptomes gastrointestinals iproblemes en l’alimentació, probablement causats per ladificultat d’accés a la llet materna pròpia per gravetat clínicao derivats de la inflamació en el context perinatal.Conclusions. Es tracta d’una mostra petita, de manera quesón necessaris més estudis per poder extreure’n conclusions. (AU)

Fundamento. En los meses de julio y agosto de 2021, coincidiendocon la ola de SARS-CoV-2 debida a la variante delta del virus y ala vacunación poblacional incompleta, en el Hospital Vall d’Hebronhubo varios ingresos de recién nacidos prematuros debido a neumonía grave materna, al ser este un centro de referencia paragestantes con infección por covid-19 grave. En este trabajo serecogen las características más relevantes de dicha población.Objetivo. Describir la experiencia con recién nacidos prematuros acausa de neumonía grave por covid-19 materna. Método. Se trata de un trabajo descriptivo que reúne los casosatendidos en nuestro hospital durante dos meses y muestra susprincipales características clínicas.Resultados.La mayoría de los pacientes fueron negativos paraSARS-CoV-2 en los aspirados realizados durante su ingreso, norequirieron soporte respiratorio prolongado ni presentaron patologías importantes más allá de las asociadas a su prematuridad.Destaca la frecuencia de síntomas gastrointestinales y problemasen la alimentación, probablemente debidos a la dificultad en elacceso a leche materna propia por gravedad clínica y/o derivadosde la inflamación en el contexto perinatal.Conclusiones. Se trata de una muestra pequeña, por lo que sonnecesarios más estudios para poder extraer conclusiones. (AU)

Background. During the months of July and August of 2021, duringthe SARS-CoV-2 delta variant wave in the context of incompletevaccination of the population in Spain, several premature newborns due to severe maternal pneumonia were admitted in Hospital Vall d’Hebron, which is a reference center for pregnant womenwith severe Covid-19 infections. In this study we describe the essential characteristics of this population.Objective. To describe the experience with premature neonates secondary to severe SARS-CoV-2 maternal pneumonia.Method. Descriptive study of the clinical characteristics of all thesenewborns admitted during the months of July and August of 2021.Results. Most of the patients were negative for SARS-CoV-2 in themicrobiological tests performed, most of them did not require prolonged respiratory support and most of them did not present significant pathologies beyond those associated with their prematurity.There was a high frequency of gastrointestinal symptoms and feeding problems, mostly related to difficulties in accessing to breastmilk due to maternal clinical severity and possibly to perinatalinflammatory context.Conclusions. Considering the small sample size, more studies arenecessary to further describe this population. (AU)

Impact of Covalent Functionalization on the Aqueous Processability, Catalytic Activity, and Biocompatibility of Chemically Exfoliated MoS2 Nanosheets.

Chemically exfoliated MoS2 (ce-MoS2) has emerged in recent years as an attractive two-dimensional material for use in relevant technological applications, but fully exploiting its potential and versatility will most probably require the deployment of appropriate chemical modification strategies. Here, we demonstrate that extensive covalent functionalization of ce-MoS2 nanosheets with acetic acid groups (∼0.4 groups grafted per MoS2 unit) based on the organoiodide chemistry brings a number of benefits in terms of their processability and functionality. Specifically, the acetic acid-functionalized nanosheets were furnished with long-term (>6 months) colloidal stability in aqueous medium at relatively high concentrations, exhibited a markedly improved temporal retention of catalytic activity toward the reduction of nitroarenes, and could be more effectively coupled with silver nanoparticles to form hybrid nanostructures. Furthermore, in vitro cell proliferation tests carried out with murine fibroblasts suggested that the chemical derivatization had a positive effect on the biocompatibility of ce-MoS2. A hydrothermal annealing procedure was also implemented to promote the structural conversion of the functionalized nanosheets from the 1T phase that was induced during the chemical exfoliation step to the original 2H phase of the starting bulk material, while retaining at the same time the aqueous colloidal stability afforded by the presence of the acetic acid groups. Overall, by highlighting the benefits of this type of chemical derivatization, the present work should contribute to strengthen the position of ce-MoS2 as a two-dimensional material of significant practical utility.

Chemically exfoliated MoS2 nanosheets as an efficient catalyst for reduction reactions in the aqueous phase.

Chemically exfoliated MoS2 (ce-MoS2) nanosheets that incorporate a large fraction of metallic 1T phase have been recently shown to possess a high electrocatalytic activity in the hydrogen evolution reaction, but the potential of this two-dimensional material as a catalyst has otherwise remained mostly uncharted. Here, we demonstrate that ce-MoS2 nanosheets are efficient catalysts for a number of model reduction reactions (namely, those of 4-nitrophenol, 4-nitroaniline, methyl orange, and [Fe(CN)6](3-)) carried out in aqueous medium using NaBH4 as a reductant. The performance of the nanosheets in these reactions is found to be comparable to that of many noble metal-based catalysts. The possible reaction pathways involving ce-MoS2 as a catalyst are also discussed and investigated. Overall, the present results expand the scope of this two-dimensional material as a competitive, inexpensive, and earth-abundant catalyst.

Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

BACKGROUND: Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 - 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. PRINCIPAL FINDINGS: Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands. CONCLUSIONS/SIGNIFICANCE: Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century.

The primary habitat of polar bears is sea ice, but in Western Hudson Bay (WH), the seasonal ice cycle forces polar bears ashore each summer. Survival of bears on land in WH is correlated with breakup and the ice-free season length, and studies suggest that exceeding thresholds in these variables will lead to large declines in the WH population. To estimate when anthropogenic warming may have progressed sufficiently to threaten the persistence of polar bears in WH, we predict changes in the ice cycle and the sea ice concentration (SIC) in spring (the primary feeding period of polar bears) with a high-resolution sea ice-ocean model and warming forced with 21st century IPCC greenhouse gas (GHG) emission scenarios: B1 (low), A1B (medium), and A2 (high). We define critical years for polar bears based on proposed thresholds in breakup and ice-free season and we assess when ice-cycle conditions cross these thresholds. In the three scenarios, critical years occur more commonly after 2050. From 2001 to 2050, 2 critical years occur under B1 and A2, and 4 under A1B; from 2051 to 2100, 8 critical years occur under B1, 35 under A1B and 41 under A2. Spring SIC in WH is high (>90%) in all three scenarios between 2001 and 2050, but declines rapidly after 2050 in A1B and A2. From 2090 to 2100, the mean spring SIC is 84 (±7)% in B1, 56 (±26)% in A1B and 20 (±13)% in A2. Our predictions suggest that the habitat of polar bears in WH will deteriorate in the 21st century. Ice predictions in A1B and A2 suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century.