Nutrición enteral en pacientes críticos con COVID-19 ventilados en decúbito prono

Introducción: el SARS-CoV-2 desde el 2020 generó innumerables desafíos. El decúbito prono se utilizó para mejorar la oxigenación, y la terapia nutricional se adaptó para cubrir los requerimientos y reducir complicaciones. Objetivos: evaluar la tolerancia de la nutrición enteral y su adecuación energética en pacientes ventilados en decúbito prono con infección por SARS-CoV-2, en sala respiratoria del Departamento de Cuidados Intensivos Adultos del Hospital de Clínicas-Facultad de Ciencias Médicas - Universidad Nacional de Asunción, de marzo a julio 2021. Metodología: estudio observacional, descriptivo, retrospectivo, de corte transversal, de casos consecutivos, con información obtenida de fichas de pacientes de terapia intensiva, que recibieron soporte nutricional en posición prona. Se tomaron datos demográficos, clínicos y nutricionales. Se evaluó la tolerancia nutricional durante la posición prona, definiéndola como la presencia de un volumen de residuo gástrico < 500 mL cada 6 h.. La adecuación energética fue determinada teniendo en cuenta el porcentaje cumplido de la prescripción nutricional. Resultados: se reclutaron 41 pacientes. El 60,9 % eran hombres; la mediana de edad fue 55 años (RIC=23). Las principales comorbilidades fueron obesidad (57,3 %) e hipertensión arterial (43,9 %). El 85,4 % presentó buena tolerancia gástrica en posición prono, con residuo gástrico menor a 500 ml. El porcentaje de adecuación energética fue de 84 %. Conclusión: la terapia nutricional enteral en decúbito prono fue bien tolerada por la mayoría de nuestros pacientes, posibilitando alcanzar los requerimientos nutricionales indicados.

Introduction: SARS-CoV-2 since 2020 has generated countless challenges. Prone position was used to improve oxygenation, and nutritional therapy was adapted to meet requirements and reduce complications. Objectives: evaluate the tolerance of enteral nutrition and its energetic adequacy in ventilated patients in the prone position with SARS-CoV-2 infection, in the respiratory room of the Adult Intensive Care Department of the Hospital de Clínicas - Facultad de Ciencias Médicas - Universidad Nacional de Asunción, from March to July 2021. Methodology: observational, descriptive, retrospective, cross-sectional study of consecutive cases, with information obtained from records of intensive care patients, who received nutritional support in a prone position. Demographic, clinical and nutritional data were taken. Nutritional tolerance was evaluated during the prone position, defining it as the presence of a volume of gastric residue < 500 mL every 6 h. Energy adequacy was determined taking into account the percentage fulfilled of the nutritional prescription. Results: 41 patients were recruited. 60.9 % were men; the median age was 55 years (IQR=23). The main comorbidities were obesity (57.3 %) and high blood pressure (43.9 %). 85.4 % had good gastric tolerance in the prone position, with gastric residue less than 500 ml. The percentage of energy adequacy was 84 %. Conclusion: enteral nutritional therapy in the prone position was well tolerated by the majority of our patients, making it possible to achieve the indicated nutritional requirements.

Clinical evolution and mortality of critically ill patients with SARS-CoV-2 pneumonia treated with remdesivir in an adult intensive care unit of Paraguay.

BACKGROUND: The health crisis due to Covid-19 led to the search for therapeutics that could improve the evolution of the disease. Remdesivir, an antiviral that interferes with viral replication, was one of the first to be used for the treatment of this pathology. OBJECTIVE: To determine clinical course and mortality of patients with severe SARS-CoV-2 pneumonia treated with remdesivir, in comparison of those who didn't receive the medication. PATIENTS AND METHODS: Retrospective cohort study, with medical records review of COVID-19 patients, between August 2020 and August 2021. The subjects were divided into two groups, those who received remdesivir before or after admission to intensive care and those who didn't. The primary outcome variable was mortality in intensive care. RESULTS: Of 214 subjects included, 109 (50,9%) received remdesivir. The median of days for the drug administration was 8 (2-20), IQR: 3. The bivariate analysis prove that the use of remdesivir was related with lower risk of develop Acute Respiratory Distress Syndrome (ARDS) (p = 0,019; OR: 0,521) and lower requirement of mechanical ventilation (p = 0,006; OR:0,450). Additionally, patients treated with remdesivir develop less kidney injury (p = 0,009; OR: 0,441). There was a total of 82 deaths, 29 (26,6%) in the remdesivir group and 53 (50,5%) in the control group [p < 0,001; OR: 0,356 (0,201-0,630)]. All the risk factors associated with mortality in the bivariate analysis were entered into the multivariate analysis by logistic regression, the use of remdesivir remained associated as an independent protective factor to mortality (p = 0.034; OR: 0.429). CONCLUSION: Critically ill patients with SARS-CoV-2 pneumonia treated with remdesivir had a lower risk of death and need for mechanical ventilation and develop less ARDS as compared to the control group. No differences were found in the presentation of adverse effects.

The transcription factor HSFA7b controls thermomemory at the shoot apical meristem by regulating ethylene biosynthesis and signaling in Arabidopsis.

The shoot apical meristem (SAM) is responsible for overall shoot growth by generating all aboveground structures. Recent research has revealed that the SAM displays an autonomous heat stress (HS) memory of a previous non-lethal HS event. Considering the importance of the SAM for plant growth, it is essential to determine how its thermomemory is mechanistically controlled. Here, we report that HEAT SHOCK TRANSCRIPTION FACTOR A7b (HSFA7b) plays a crucial role in this process in Arabidopsis, as the absence of functional HSFA7b results in the temporal suppression of SAM activity after thermopriming. We found that HSFA7b directly regulates ethylene response at the SAM by binding to the promoter of the key ethylene signaling gene ETHYLENE-INSENSITIVE 3 to establish thermotolerance. Moreover, we demonstrated that HSFA7b regulates the expression of ETHYLENE OVERPRODUCER 1 (ETO1) and ETO1-LIKE 1, both of which encode ethylene biosynthesis repressors, thereby ensuring ethylene homeostasis at the SAM. Taken together, these results reveal a crucial and tissue-specific role for HSFA7b in thermomemory at the Arabidopsis SAM.

Meningioma Meningotelial cerebeloso complicado con absceso único a Nocardia / Meningioma Meningotelial cerebellar complicated with unique abscess to Nocardia

La presentación de abscesos cerebrales relacionados a meningiomas es muy poco frecuente. Usualmente son causados por bacterias comunes, siendo la Nocardia un agente etiológico excepcional. Presentamos la primera descripción en Paraguay de un absceso cerebral a Nocardia Spp asociado a meningioma en un paciente inmunocomprometido por consumo prolongado de corticoides (dexametasona).

The presentation of cerebral abscesses related to meningiomas is very rare. They are usually caused by common bacteria, nocardia being an exceptional etiological agent. We present the first description in Paraguay of a cerebral abscess to Nocardia spp associated meningioma in an immunocompromised patient for prolonged corticosteroid consumption (dexamethasone).

Exact Bayesian inference for the detection of graft-mobile transcripts from sequencing data.

The long-distance transport of messenger RNAs (mRNAs) has been shown to be important for several developmental processes in plants. A popular method for identifying travelling mRNAs is to perform RNA-Seq on grafted plants. This approach depends on the ability to correctly assign sequenced mRNAs to the genetic background from which they originated. The assignment is often based on the identification of single-nucleotide polymorphisms (SNPs) between otherwise identical sequences. A major challenge is therefore to distinguish SNPs from sequencing errors. Here, we show how Bayes factors can be computed analytically using RNA-Seq data over all the SNPs in an mRNA. We used simulations to evaluate the performance of the proposed framework and demonstrate how Bayes factors accurately identify graft-mobile transcripts. The comparison with other detection methods using simulated data shows how not taking the variability in read depth, error rates and multiple SNPs per transcript into account can lead to incorrect classification. Our results suggest experimental design criteria for successful graft-mobile mRNA detection and show the pitfalls of filtering for sequencing errors or focusing on single SNPs within an mRNA.

Plant mitochondrial FMT and its mammalian homolog CLUH controls development and behavior in Arabidopsis and locomotion in mice.

Mitochondria in animals are associated with development, as well as physiological and pathological behaviors. Several conserved mitochondrial genes exist between plants and higher eukaryotes. Yet, the similarities in mitochondrial function between plant and animal species is poorly understood. Here, we show that FMT (FRIENDLY MITOCHONDRIA) from Arabidopsis thaliana, a highly conserved homolog of the mammalian CLUH (CLUSTERED MITOCHONDRIA) gene family encoding mitochondrial proteins associated with developmental alterations and adult physiological and pathological behaviors, affects whole plant morphology and development under both stressed and normal growth conditions. FMT was found to regulate mitochondrial morphology and dynamics, germination, and flowering time. It also affects leaf expansion growth, salt stress responses and hyponastic behavior, including changes in speed of hyponastic movements. Strikingly, Cluh± heterozygous knockout mice also displayed altered locomotive movements, traveling for shorter distances and had slower average and maximum speeds in the open field test. These observations indicate that homologous mitochondrial genes may play similar roles and affect homologous functions in both plants and animals.

Shoot and root single cell sequencing reveals tissue- and daytime-specific transcriptome profiles.

Although several large-scale single-cell RNA sequencing (scRNAseq) studies addressing the root of Arabidopsis (Arabidopsis thaliana) have been published, there is still need for a de novo reference map for both root and especially above-ground cell types. As the plants' transcriptome substantially changes throughout the day, shaped by the circadian clock, we performed scRNAseq on both Arabidopsis root and above-ground tissues at defined times of the day. For the root scRNAseq analysis, we used tissue-specific reporter lines grown on plates and harvested at the end of the day (ED). In addition, we submitted above-ground tissues from plants grown on soil at ED and end of the night to scRNAseq, which allowed us to identify common cell types/markers between root and shoot and uncover transcriptome changes to above-ground tissues depending on the time of the day. The dataset was also exploited beyond the traditional scRNAseq analysis to investigate non-annotated and di-cistronic transcripts. We experimentally confirmed the predicted presence of some of these transcripts and also addressed the potential function of a previously unidentified marker gene for dividing cells. In summary, this work provides insights into the spatial control of gene expression from nearly 70,000 cells of Arabidopsis for below- and whole above-ground tissue at single-cell resolution at defined time points.

Primary carbohydrate metabolism genes participate in heat-stress memory at the shoot apical meristem of Arabidopsis thaliana.

In plants, the shoot apical meristem (SAM) is essential for the growth of aboveground organs. However, little is known about its molecular responses to abiotic stresses. Here, we show that the SAM of Arabidopsis thaliana displays an autonomous heat-stress (HS) memory of a previous non-lethal HS, allowing the SAM to regain growth after exposure to an otherwise lethal HS several days later. Using RNA sequencing, we identified genes participating in establishing the SAM's HS transcriptional memory, including the stem cell (SC) regulators CLAVATA1 (CLV1) and CLV3, HEAT SHOCK PROTEIN 17.6A (HSP17.6A), and the primary carbohydrate metabolism gene FRUCTOSE-BISPHOSPHATE ALDOLASE 6 (FBA6). We demonstrate that sugar availability is essential for survival of plants at high temperature. HEAT SHOCK TRANSCRIPTION FACTOR A2 (HSFA2A) directly regulates the expression of HSP17.6A and FBA6 by binding to the heat-shock elements in their promoters, indicating that HSFA2 is required for transcriptional activation of SAM memory genes. Collectively, these findings indicate that plants have evolved a sophisticated protection mechanism to maintain SCs and, hence, their capacity to re-initiate shoot growth after stress release.

Developmental stage-specific metabolite signatures in Arabidopsis thaliana under optimal and mild nitrogen limitation.

Metabolites influence flowering time, and thus are among the major determinants of yield. Despite the reported role of trehalose 6-phosphate and nitrate signaling on the transition from the vegetative to the reproductive phase, little is known about other metabolites contributing and responding to developmental phase changes. To increase our understanding which metabolic traits change throughout development in Arabidopsis thaliana and to identify metabolic markers for the vegetative and reproductive phases, especially among individual amino acids (AA), we profiled metabolites of plants grown in optimal (ON) and limited nitrogen (N) (LN) conditions, the latter providing a mild but consistent limitation of N. We found that although LN plants adapt their growth to a decreased level of N, their metabolite profiles are strongly distinct from ON plant profiles, with N as the driving factor for the observed differences. We demonstrate that the vegetative and the reproductive phase are not only marked by growth parameters such as biomass and rosette area, but also by specific metabolite signatures including specific single AA. In summary, we identified N-dependent and -independent indicators manifesting developmental stages, indicating that the plant's metabolic status also reports on the developmental phases.

Physiological Profiling of Embryos and Dormant Seeds in Two Arabidopsis Accessions Reveals a Metabolic Switch in Carbon Reserve Accumulation.

In flowering plants, sugars act as carbon sources providing energy for developing embryos and seeds. Although most studies focus on carbon metabolism in whole seeds, knowledge about how particular sugars contribute to the developmental transitions during embryogenesis is scarce. To develop a quantitative understanding of how carbon composition changes during embryo development, and to determine how sugar status contributes to final seed or embryo size, we performed metabolic profiling of hand-dissected embryos at late torpedo and mature stages, and dormant seeds, in two Arabidopsis thaliana accessions with medium [Columbia-0 (Col-0)] and large [Burren-0 (Bur-0)] seed sizes, respectively. Our results show that, in both accessions, metabolite profiles of embryos largely differ from those of dormant seeds. We found that developmental transitions from torpedo to mature embryos, and further to dormant seeds, are associated with major metabolic switches in carbon reserve accumulation. While glucose, sucrose, and starch predominantly accumulated during seed dormancy, fructose levels were strongly elevated in mature embryos. Interestingly, Bur-0 seeds contain larger mature embryos than Col-0 seeds. Fructose and starch were accumulated to significantly higher levels in mature Bur-0 than Col-0 embryos, suggesting that they contribute to the enlarged mature Bur-0 embryos. Furthermore, we found that Bur-0 embryos accumulated a higher level of sucrose compared to hexose sugars and that changes in sucrose metabolism are mediated by sucrose synthase (SUS), with SUS genes acting non-redundantly, and in a tissue-specific manner to utilize sucrose during late embryogenesis.

All roads lead to growth: imaging-based and biochemical methods to measure plant growth.

Plant growth is a highly complex biological process that involves innumerable interconnected biochemical and signalling pathways. Many different techniques have been developed to measure growth, unravel the various processes that contribute to plant growth, and understand how a complex interaction between genotype and environment determines the growth phenotype. Despite this complexity, the term 'growth' is often simplified by researchers; depending on the method used for quantification, growth is viewed as an increase in plant or organ size, a change in cell architecture, or an increase in structural biomass. In this review, we summarise the cellular and molecular mechanisms underlying plant growth, highlight state-of-the-art imaging and non-imaging-based techniques to quantitatively measure growth, including a discussion of their advantages and drawbacks, and suggest a terminology for growth rates depending on the type of technique used.

m5C Methylation Guides Systemic Transport of Messenger RNA over Graft Junctions in Plants.

In plants, transcripts move to distant body parts to potentially act as systemic signals regulating development and growth. Thousands of messenger RNAs (mRNAs) are transported across graft junctions via the phloem to distinct plant parts. Little is known regarding features, structural motifs, and potential base modifications of transported transcripts and how these may affect their mobility. We identified Arabidopsis thaliana mRNAs harboring the modified base 5-methylcytosine (m5C) and found that these are significantly enriched in mRNAs previously described as mobile, moving over graft junctions to distinct plant parts. We confirm this finding with graft-mobile methylated mRNAs TRANSLATIONALLY CONTROLLED TUMOR PROTEIN 1 (TCTP1) and HEAT SHOCK COGNATE PROTEIN 70.1 (HSC70.1), whose mRNA transport is diminished in mutants deficient in m5C mRNA methylation. Together, our results point toward an essential role of cytosine methylation in systemic mRNA mobility in plants and that TCTP1 mRNA mobility is required for its signaling function.

Response of Arabidopsis primary metabolism and circadian clock to low night temperature in a natural light environment.

Plants are exposed to varying irradiance and temperature within a day and from day to day. We previously investigated metabolism in a temperature-controlled greenhouse at the spring equinox on both a cloudy and a sunny day [daily light integral (DLI) of 7 mol m-2 d-1 and 12 mol m-2 d-1]. Diel metabolite profiles were largely captured in sinusoidal simulations at similar DLIs in controlled-environment chambers, except that amino acids were lower in natural light regimes. We now extend the DLI12 study by investigating metabolism in a natural light regime with variable temperature including cool nights. Starch was not completely turned over, anthocyanins and proline accumulated, and protein content rose. Instead of decreasing, amino acid content rose. Connectivity in central metabolism, which decreased in variable light, was not further weakened by variable temperature. We propose that diel metabolism operates better when light and temperature are co-varying. We also compared transcript abundance of 10 circadian clock genes in this temperature-variable regime with the temperature-controlled natural and sinusoidal light regimes. Despite temperature compensation, peak timing and abundance for dawn- and day-phased genes and GIGANTEA were slightly modified in the variable temperature treatment. This may delay dawn clock activity until the temperature rises enough to support rapid metabolism and photosynthesis.

Defining Human Tyrosine Kinase Phosphorylation Networks Using Yeast as an In Vivo Model Substrate.

Systematic assessment of tyrosine kinase-substrate relationships is fundamental to a better understanding of cellular signaling and its profound alterations in human diseases such as cancer. In human cells, such assessments are confounded by complex signaling networks, feedback loops, conditional activity, and intra-kinase redundancy. Here we address this challenge by exploiting the yeast proteome as an in vivo model substrate. We individually expressed 16 human non-receptor tyrosine kinases (NRTKs) in Saccharomyces cerevisiae and identified 3,279 kinase-substrate relationships involving 1,351 yeast phosphotyrosine (pY) sites. Based on the yeast data without prior information, we generated a set of linear kinase motifs and assigned ∼1,300 known human pY sites to specific NRTKs. Furthermore, experimentally defined pY sites for each individual kinase were shown to cluster within the yeast interactome network irrespective of linear motif information. We therefore applied a network inference approach to predict kinase-substrate relationships for more than 3,500 human proteins, providing a resource to advance our understanding of kinase biology.

Getting back to nature: a reality check for experiments in controlled environments.

Irradiance from sunlight changes in a sinusoidal manner during the day, with irregular fluctuations due to clouds, and light-dark shifts at dawn and dusk are gradual. Experiments in controlled environments typically expose plants to constant irradiance during the day and abrupt light-dark transitions. To compare the effects on metabolism of sunlight versus artificial light regimes, Arabidopsis thaliana plants were grown in a naturally illuminated greenhouse around the vernal equinox, and in controlled environment chambers with a 12-h photoperiod and either constant or sinusoidal light profiles, using either white fluorescent tubes or light-emitting diodes (LEDs) tuned to a sunlight-like spectrum as the light source. Rosettes were sampled throughout a 24-h diurnal cycle for metabolite analysis. The diurnal metabolite profiles revealed that carbon and nitrogen metabolism differed significantly between sunlight and artificial light conditions. The variability of sunlight within and between days could be a factor underlying these differences. Pairwise comparisons of the artificial light sources (fluorescent versus LED) or the light profiles (constant versus sinusoidal) showed much smaller differences. The data indicate that energy-efficient LED lighting is an acceptable alternative to fluorescent lights, but results obtained from plants grown with either type of artificial lighting might not be representative of natural conditions.

Circadian, Carbon, and Light Control of Expansion Growth and Leaf Movement.

We used Phytotyping4D to investigate the contribution of clock and light signaling to the diurnal regulation of rosette expansion growth and leaf movement in Arabidopsis (Arabidopsis thaliana). Wild-type plants and clock mutants with a short (lhycca1) and long (prr7prr9) period were analyzed in a T24 cycle and in T-cycles that were closer to the mutants' period. Wild types also were analyzed in various photoperiods and after transfer to free-running light or darkness. Rosette expansion and leaf movement exhibited a circadian oscillation, with superimposed transients after dawn and dusk. Diurnal responses were modified in clock mutants. lhycca1 exhibited an inhibition of growth at the end of night and growth rose earlier after dawn, whereas prr7prr9 showed decreased growth for the first part of the light period. Some features were partly rescued by a matching T-cycle, like the inhibition in lhycca1 at the end of the night, indicating that it is due to premature exhaustion of starch. Other features were not rescued, revealing that the clock also regulates expansion growth more directly. Expansion growth was faster at night than in the daytime, whereas published work has shown that the synthesis of cellular components is faster in the day than at nighttime. This temporal uncoupling became larger in short photoperiods and may reflect the differing dependence of expansion and biosynthesis on energy, carbon, and water. While it has been proposed that leaf expansion and movement are causally linked, we did not observe a consistent temporal relationship between expansion and leaf movement.

Cellulose Synthesis and Cell Expansion Are Regulated by Different Mechanisms in Growing Arabidopsis Hypocotyls.

Plant growth is sustained by two complementary processes: biomass biosynthesis and cell expansion. The cell wall is crucial to both as it forms the majority of biomass, while its extensibility limits cell expansion. Cellulose is a major component of the cell wall and cellulose synthesis is pivotal to plant cell growth, and its regulation is poorly understood. Using periodic diurnal variation in Arabidopsis thaliana hypocotyl growth, we found that cellulose synthesis and cell expansion can be uncoupled and are regulated by different mechanisms. We grew Arabidopsis plants in very short photoperiods and used a combination of extended nights, continuous light, sucrose feeding experiments, and photosynthesis inhibition to tease apart the influences of light, metabolic, and circadian clock signaling on rates of cellulose biosynthesis and cell wall biomechanics. We demonstrate that cell expansion is regulated by protein-mediated changes in cell wall extensibility driven by the circadian clock. By contrast, the biosynthesis of cellulose is controlled through intracellular trafficking of cellulose synthase enzyme complexes regulated exclusively by metabolic signaling related to the carbon status of the plant and independently of the circadian clock or light signaling.

Gpr161 anchoring of PKA consolidates GPCR and cAMP signaling.

Scaffolding proteins organize the information flow from activated G protein-coupled receptors (GPCRs) to intracellular effector cascades both spatially and temporally. By this means, signaling scaffolds, such as A-kinase anchoring proteins (AKAPs), compartmentalize kinase activity and ensure substrate selectivity. Using a phosphoproteomics approach we identified a physical and functional connection between protein kinase A (PKA) and Gpr161 (an orphan GPCR) signaling. We show that Gpr161 functions as a selective high-affinity AKAP for type I PKA regulatory subunits (RI). Using cell-based reporters to map protein-protein interactions, we discovered that RI binds directly and selectively to a hydrophobic protein-protein interaction interface in the cytoplasmic carboxyl-terminal tail of Gpr161. Furthermore, our data demonstrate that a binary complex between Gpr161 and RI promotes the compartmentalization of Gpr161 to the plasma membrane. Moreover, we show that Gpr161, functioning as an AKAP, recruits PKA RI to primary cilia in zebrafish embryos. We also show that Gpr161 is a target of PKA phosphorylation, and that mutation of the PKA phosphorylation site affects ciliary receptor localization. Thus, we propose that Gpr161 is itself an AKAP and that the cAMP-sensing Gpr161:PKA complex acts as cilium-compartmentalized signalosome, a concept that now needs to be considered in the analyzing, interpreting, and pharmaceutical targeting of PKA-associated functions.