Toxicity of airborne nanoparticles: Facts and challenges.

Air pollution is one of the most severe environmental healthhazards, and airborne nanoparticles (diameter <100 nm) are considered particularly hazardous to human health. They are produced by various sources such as internal combustion engines, wood and biomass burning, and fuel and natural gas combustion, and their origin, among other parameters, determines their intrinsic toxicity for reasons that are not yet fully understood. Many constituents of the nanoparticles are considered toxic or at least hazardous, including polycyclic aromatic hydrocarbons (PAHs) and heavy metal compounds, in addition to gaseous pollutants present in the aerosol fraction, such as NOx, SO2, and ozone. All these compounds can cause oxidative stress, mitochondrial damage, inflammation in the lungs and other tissues, and cellular organelles. Epidemiological investigations concluded that airborne pollution may affect the respiratory, cardiovascular, and nervous systems. Moreover, particulate matter has been linked to an increased risk of lung cancer, a carcinogenic effect not related to DNA damage, but to the cellular inflammatory response to the pollutants, in which the release of cytokines promotes the proliferation of pre-existing mutated cancer cells. The mechanisms behind toxicity can be investigated experimentally using cell cultures or animal models. Methods for gathering particulate matter have been explored, but standardized protocols are needed to ensure that the samples accurately represent chemical mixtures in the environment. Toxic constituents of nanoparticles can be studied in animal and cellular models, but designing realistic exposure settings is challenging. The air-liquid interface (ALI) system directly exposes cells, mimicking particle inhalation into the lungs. Continuous research and monitoring of nanoparticles and other airborne pollutants is essential for understanding their effects and developing active strategies to mitigate their risks to human and environmental health.

Mithramycin and its analogs: Molecular features and antitumor action.

The antitumor antibiotic mithramycin A (MTA) binds to G/C-rich DNA sequences in the presence of dications. MTA inhibits transcription regulated by the Sp1 transcription factor, often enhanced during tumor development. It shows antitumor activity, but its clinical use was discontinued due to toxic side effects. However, recent observations have led to its use being reconsidered. The MTA biosynthetic pathways have been modified to produce mithramycin analogs (mithralogs) that encompass lower toxicity and improved pharmacological activity. Some mithralogs reduce gene expression in human ovarian and prostate tumors, among other types of cancer. They down-regulate gene expression in various cellular processes, including Sp1-responsive genes that control tumor development. Moreover, MTA and several mithralogs, such as EC-8042 (DIG-MSK) and EC-8105, effectively treat Ewing sarcoma by inhibiting transcription controlled by the oncogenic EWS-FLI1 transcription factor.

Efficient removal of toxicity associated to wastewater treatment plant effluents by enhanced Soil Aquifer Treatment.

The regeneration of wastewater has been recognized as an effective strategy to counter water scarcity. Nonetheless, Wastewater Treatment Plant (WWTP) effluents still contain a wide range of contaminants of emerging concern (CECs) even after water depuration. Filtration through Soil Aquifer Treatment (SAT) systems has proven efficient for CECs removal although the attenuation of their associated biological effects still remains poorly understood. To evaluate this, three pilot SAT systems were monitored, two of them enhanced with different reactive barriers. SATs were fed with secondary effluents during two consecutive campaigns. Fifteen water samples were collected from the WWTP effluent, below the barriers and 15 m into the aquifer. The potential attenuation of effluent-associated biological effects by SATs was evaluated through toxicogenomic bioassays using zebrafish eleutheroembryos and human hepatic cells. Transcriptomic analyses revealed a wide range of toxic activities exerted by the WWTP effluents that were reduced by more than 70% by SAT. Similar results were observed when HepG2 hepatic cells were tested for cytotoxic and dioxin-like responses. Toxicity reduction appeared partially determined by the barrier composition and/or SAT managing and correlated with CECs removal. SAT appears as a promising approach to efficiently reduce effluent-associated toxicity contributing to environmental and human health preservation.

Linking the use of reclaimed water to indicators of crop stress by metabolomic and transcriptomic analyses. A tool to compare water irrigation quality.

The occurrence of contaminants of emerging concern (CECs) or heavy metals in reclaimed water used for agricultural irrigation may affect crop morphology and physiology. Here, we analyzed lettuce (Lactuca sativa) grown in outdoor lysimeters and irrigated with either tap water, used as a control, or reclaimed water: CAS-reclaimed water, an effluent from a conventional activated sludge system (CAS) followed by chlorination and sand filtration, or MBR-reclaimed water, an effluent from a membrane biological reactor (MBR). Chemical analyses identified seven CECs in the reclaimed waters, but only two of them were detected in lettuce (carbamazepine and azithromycin). Metabolomic and transcriptomic analyses revealed that irrigation with reclaimed water increased the concentrations of several crop metabolites (5-oxoproline, leucine, isoleucine, and fumarate) and of transcripts codifying for the plant stress-related genes Heat-Shock Protein 70 (HSP70) and Manganese Superoxide Dismutase (MnSOD). In both cases, MBR-water elicited the strongest response in lettuce, perhaps related to its comparatively high sodium adsorption ratio (4.5), rather than to its content in CECs or heavy metals. Our study indicates that crop metabolomic and transcriptomic profiles depend on the composition of irrigating water and that they could be used for testing the impact of water quality in agriculture.

Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes.

Exposure to particulate matter (PM) has been associated with a wide range of adverse health effects, but it is still unclear how particles from various transport modes differ in terms of toxicity and associations with different human health outcomes. This literature review aims to summarize toxicological and epidemiological studies of the effect of ultrafine particles (UFPs), also called nanoparticles (NPs, <100 nm), from different transport modes with a focus on vehicle exhaust (particularly comparing diesel and biodiesel) and non-exhaust as well as particles from shipping (harbor), aviation (airport) and rail (mainly subway/underground). The review includes both particles collected in laboratory tests and the field (intense traffic environments or collected close to harbor, airport, and in subway). In addition, epidemiological studies on UFPs are reviewed with special attention to studies aimed at distinguishing the effects of different transport modes. Results from toxicological studies indicate that both fossil and biodiesel NPs show toxic effects. Several in vivo studies show that inhalation of NPs collected in traffic environments not only impacts the lung, but also triggers cardiovascular effects as well as negative impacts on the brain, although few studies compared NPs from different sources. Few studies were found on aviation (airport) NPs, but the available results suggest similar toxic effects as traffic-related particles. There is still little data related to the toxic effects linked to several sources (shipping, road and tire wear, subway NPs), but in vitro results highlighted the role of metals in the toxicity of subway and brake wear particles. Finally, the epidemiological studies emphasized the current limited knowledge of the health impacts of source-specific UFPs related to different transport modes. This review discusses the necessity of future research for a better understanding of the relative potencies of NPs from different transport modes and their use in health risk assessment.

Acessibilidade geográfica aos serviços de reabilitação de crianças com síndrome congênita do vírus Zika / Geographical accessibility to rehabilitation services of children with congenital zika syndrome

Resumo Introdução Alterações neurológicas em crianças com síndrome congênita do vírus Zika (SCZ) repercutem em atrasos no desenvolvimento e deformidades, levando à necessidade da assistência aos serviços de reabilitação. Objetivo Analisar a acessibilidade geográfica de crianças com SCZ na Região Metropolitana do Recife (RMR) e compará-la com a otimizada (distância mais próxima entre a residência da criança e o serviço). Método Estudo descritivo, incluindo 51 crianças com SCZ que residiam na RMR. Utilizaram-se questionários semiestruturados com dados sociodemográficos, econômicos e informações dos serviços de reabilitação utilizados pela criança. Elaboraram-se mapas de distribuição espacial e fluxos pelo Sistema de Informação Geográfica QGis e análises descritivas do perfil da amostra, usando SPSS 20.0. Resultados A maioria era de crianças que viviam em locais de vulnerabilidade, considerando a renda como indicador. Quanto à acessibilidade, os serviços de reabilitação estavam concentrados na cidade do Recife, levando 37,3% das crianças a percorrer acima de 15 km até os serviços. Verificou-se que numa acessibilidade otimizada, 52,9% percorreriam entre 1 e 5 km. Conclusão Uma reorganização dos serviços para garantir maior facilidade de acessibilidade a essas crianças é necessária e imprescindível para garantia de melhor acompanhamento e assistência dessas famílias em longo prazo.

Abstract Background Neurological changes in children with congenital zika virus syndrome (CZS) have delays in development and deformities, leading to the need care for rehabilitation services Objective This study aims to analyze the geographical accessibility of children with CZS in the Metropolitan Region of Recife (RMR), and to compare such with the optimized (closest distance between the child's residence and the service). Method It is a descriptive study, including 51 CZS who resided in the RMR. The instruments used were semi structured questionnaire with sociodemographic data, economic and information from the centers attended by the child. Spatial distribution maps and flows were prepared by the Geographic Information System-QGis and descriptive analyzes of the sample profile, using SPSS 20.0. Results The majority were children who lived in locales of socioeconomic vulnerability. As for the accessibility, it was noted that the rehabilitation services which received these children were concentrated in the city of Recife, leading 37.3% of children to travel over 15 km to services. However, the optimal accessibility, 52,9% would be between 1 and 5 km. Conclusion A reorganization of these services to facilitate accessibility to these children, as well as a follow-up towards better tending to these families in the long term.

Perspectives on the Use of Toxicogenomics to Assess Environmental Risk.

Environmental toxicogenomics aims to collect, analyze and interpret data on changes in gene expression and protein activity resulting from exposure to toxic substances using high-performance omics technologies. Molecular profiling methods such as genomics, transcriptomics, proteomics, metabolomics, and bioinformatics techniques, permit the simultaneous analysis of a multitude of gene variants in an organism exposed to toxic agents to search for genes prone to damage, detect patterns and mechanisms of toxicity, and identify specific gene expression profiles that can provide biomarkers of exposure and risk. Compared to previous approaches to measuring molecular changes caused by toxicants, toxicogenomic technologies can improve environmental risk assessment while reducing animal studies. We discuss the prospects and limitations of converting omic datasets into valuable information, focusing on assessing the risks of mixed toxic substances to the environment and human health.

Molybdenum Foliar Fertilization Improves Photosynthetic Metabolism and Grain Yields of Field-Grown Soybean and Maize.

Foliar fertilization has been used as a supplemental strategy to plant nutrition especially in crops with high yield potential. Applying nutrients in small doses stimulates photosynthesis and increases yield performance. The aim of this study was to evaluate the efficiency of foliar application of molybdenum (Mo) to soybean and maize. The treatments consisted of the presence (+Mo) and absence (-Mo) of supplementation. Plant nutritional status, nitrate reductase (NR) activity, gas exchange parameters, photosynthetic enzyme activity (Rubisco in soybean and maize and PEPcase in maize), total soluble sugar concentration, leaf protein content, shoot dry matter, shoot nitrogen accumulated, number of grains per plant, mass of 100 grains, and grain yield were evaluated. For soybean and maize, application of Mo increased leaf NR activity, nitrogen and protein content, Rubisco activity, net photosynthesis, and grain yield. These results indicate that foliar fertilization with Mo can efficiently enhance nitrogen metabolism and the plant's response to carbon fixation, resulting in improved crop yields.

Bacillus subtilis Inoculation Improves Nutrient Uptake and Physiological Activity in Sugarcane under Drought Stress.

Sugarcane (Saccharum spp.) is one of the most important crops in the world. Throughout the sugarcane's growth stages, periods of drought are common, causing detrimental effects on plant growth. Therefore, the search for strategies for minimizing the impact of drought on sugarcane development is of great interest. Plant growth-promoting bacteria hold the potential for improving tolerance to drought in agricultural systems. Thus, the present study aimed to evaluate whether inoculation with Bacillus subtilis can reduce the negative effects of drought on the nutritional, physiological, and morphological characteristics of sugarcane plants. For this, sugarcane was cultivated in a greenhouse, under controlled conditions of water and temperature, with the aid of four treatments: without and with inoculation of B. subtilis, in normal conditions of water availability, and in conditions of water restriction (2 × 2 factorial), with four replications. In treatments with inoculation, the pre-emerged seedlings were immersed in a B. subtilis solution and transplanted into experimental pots. Our results showed that inoculation with B. subtilis improved plant nutrition and chlorophyll concentrations. As a result, the gas exchange parameters (especially net photosynthetic rate and water use efficiency) were also improved, even under drought conditions. In addition, stress parameters (antioxidant metabolism activity) were reduced in inoculated plants. The sum of these beneficial effects resulted in increased root growth, tillering, stalk weight, and higher sucrose concentration in the stalks.

Impact of sowing dates on the yield efficiency of upland rice cultivars

The choice of cultivars adapted to different regions and the determination of the best sowing dates are indispensable tools for crop development. This allows the installation of the crop in times favorable to its development, as well as cultivars that manage to reach their maximum yield potential. The objective of this study was to determine the best sowing dates and the cultivars that can adapt to the low-altitude Cerrado region and have the best development and yield efficiency. The experiment was conducted on a typical clayey dystrophic Red Latosol soil. The experimental design was in randomized blocks in a factorial scheme, comprised by four sowing dates during the spring/summer season (October, November, December, and February) and in each sowing date there were eight upland rice cultivars (BRS Esmeralda, ANa 6005, ANa 5015, IPR 117, IAC 203, IAC 500, ANa 7211 and BRSGO Serra Dourada) with four replicates. Sowing in October and November benefited the aerial dry mass and the spikelets fertility however, sowing in November provided higher plant height, which caused lodging in plants. Sowing in December caused the incidence of scald, mainly affecting the cultivar ANa 7211. For all cultivars, sowing in October favored the yield efficiency of upland rice in the low-altitude Cerrado, followed by sowing in November. The cultivars which demonstrated higher yield efficiency in the conditions of the region were BRS Esmeralda and ANa 5015.

Dynamics of Macronutrient Uptake and Removal by Modern Peanut Cultivars.

The productive potential of new peanut cultivars has increased over the years in relation to old cultivars, especially when compared with ones with upright growth habit. Thus, the requirement for macronutrients for these new cultivars may also have increased, making the existing fertilizer recommendation tables obsolete, thus increasing the need for further studies measuring the real macronutrient requirements of these new peanut cultivars. Our study aimed to evaluate the growth patterns and the macronutrient absorption rate throughout the biological cycle of three modern runner peanut cultivars, as well as the potential for producing dry matter, pods, and kernels, and their respective macronutrient accumulations. The experimental design was a randomized complete block with split-plots and nine replications. The experimental plots consisted of three peanut cultivars (IAC Runner 886, IAC 505, and IAC OL3), and subplots consisted of nine plant samplings (14, 28, 42, 56, 70, 84, 105, 126, and 147 days after emergence (DAE)). Our results showed that modern peanut cultivars presented nutrient accumulation around 30 to 40 days earlier than older cultivars, as well as increasing the uptake by K and Ca. IAC 505 absorbed higher amounts of macronutrients and resulted in greater dry matter production compared with IAC OL3 and IAC Runner 886. Our study demonstrated that the most appropriate time for plants to find greater availability of nutrients in the soil is 70 to 84 DAE, in addition to highlighting the need for updates on nutritional recommendations for higher yields of modern peanut cultivars.

Long-Term Lime and Phosphogypsum Amended-Soils Alleviates the Field Drought Effects on Carbon and Antioxidative Metabolism of Maize by Improving Soil Fertility and Root Growth.

Long-term surface application of lime (L) and/or phosphogypsum (PG) in no-till (NT) systems can improve plant growth and physiological and biochemical processes. Although numerous studies have examined the effects of L on biomass and plant growth, comprehensive evaluations of the effects of this practice on net CO2 assimilation, antioxidant enzyme activities and sucrose synthesis are lacking. Accordingly, this study examined the effects of long-term surface applications of L and PG on soil fertility and the resulting impacts on root growth, plant nutrition, photosynthesis, carbon and antioxidant metabolism, and grain yield (GY) of maize established in a dry winter region. At the study site, the last soil amendment occurred in 2016, with the following four treatments: control (no soil amendments), L (13 Mg ha-1), PG (10 Mg ha-1), and L and PG combined (LPG). The long-term effects of surface liming included reduced soil acidity and increased the availability of P, Ca2+, and Mg2+ throughout the soil profile. Combining L with PG strengthened these effects and also increased SO4 2--S. Amendment with LPG increased root development at greater depths and improved maize plant nutrition. These combined effects increased the concentrations of photosynthetic pigments and gas exchange even under low water availability. Furthermore, the activities of Rubisco, sucrose synthase and antioxidative enzymes were improved, thereby reducing oxidative stress. These improvements in the physiological performance of maize plants led to higher GY. Overall, the findings support combining soil amendments as an important strategy to increase soil fertility and ensure crop yield in regions where periods of drought occur during the cultivation cycle.

Magnesium Foliar Supplementation Increases Grain Yield of Soybean and Maize by Improving Photosynthetic Carbon Metabolism and Antioxidant Metabolism.

(1) Background: The aim of this study was to explore whether supplementary magnesium (Mg) foliar fertilization to soybean and maize crops established in a soil without Mg limitation can improve the gas exchange and Rubisco activity, as well as improve antioxidant metabolism, converting higher plant metabolism into grain yield. (2) Methods: Here, we tested foliar Mg supplementation in soybean followed by maize. Nutritional status of plants, photosynthesis, PEPcase and Rubisco activity, sugar concentration on leaves, oxidative stress, antioxidant metabolism, and finally the crops grain yields were determined. (3) Results: Our results demonstrated that foliar Mg supplementation increased the net photosynthetic rate and stomatal conductance, and reduced the sub-stomatal CO2 concentration and leaf transpiration by measuring in light-saturated conditions. The improvement in photosynthesis (gas exchange and Rubisco activity) lead to an increase in the concentration of sugar in the leaves before grain filling. In addition, we also confirmed that foliar Mg fertilization can improve anti-oxidant metabolism, thereby reducing the environmental stress that plants face during their crop cycle in tropical field conditions. (4) Conclusions: Our research brings the new glimpse of foliar Mg fertilization as a strategy to increase the metabolism of crops, resulting in increased grain yields. This type of biological strategy could be encouraged for wide utilization in cropping systems.

Spatial patterns of avoidable fetal mortality and social deprivation.

OBJECTIVE: To develop a social need index for stratification of municipalities and identification of priority areas for reducing fetal mortality. METHODS: ecological study, carried out in the state of Pernambuco, between 2010 and 2017. The technique of factor analysis by main components was used for the elaboration of the social need index. In the spatial analysis, the local empirical Bayesian estimator was applied and Moran's spatial autocorrelation was verified. RESULTS: The social deprivation index selected two factors that, together, explained 77.63% of the total variance. The preventable fetal mortality rate increased among strata of social need, with rates of 8.0 per thousand births (low deprivation), 8.1 per thousand (medium deprivation), 8.8 per thousand (high deprivation), and 10.7 per thousand (very high social deprivation). Some municipalities in the São Francisco and Sertão Mesoregions had both high fetal and preventable fetal mortality, in addition to a very high social deprivation rate. Conclusion: The spatial analysis identified areas with the highest risk for fetal mortality. The social deprivation index listed some determinants of fetal deaths in areas with worse living conditions. Priority areas for intervention in public policies to reduce fetal mortality and its determinants were detected.

Insights into DNA-drug interactions in the era of omics.

Despite the rise of sophisticated new targeting strategies in cancer chemotherapy, many classic DNA-binding drugs remain on the front line of the therapy against cancer. Based on examples primarily from the author's laboratory, this article reviews the capabilities of several DNA-binding drugs to alter gene expression. Research is ongoing about the molecular bases of the inhibition of gene expression and how alteration of the cellular transcriptome can commit cancer cells to die. The development of a variety of omic techniques allows us to gain insights into the effect of antitumor drugs. Genome-wide approaches provide unbiased genomic data that can facilitate a deeper understanding of the cellular response to DNA-binding drugs. Moreover, the results of large-scale genomic studies are gathered in publicly available databases that can be used in developing precision medicine in cancer treatment.

Spatial patterns of avoidable fetal mortality and social deprivation / Padrões espaciais da mortalidade fetal evitável e carência social

ABSTRACT: Objective: To develop a social need index for stratification of municipalities and identification of priority areas for reducing fetal mortality. Methods: ecological study, carried out in the state of Pernambuco, between 2010 and 2017. The technique of factor analysis by main components was used for the elaboration of the social need index. In the spatial analysis, the local empirical Bayesian estimator was applied and Moran's spatial autocorrelation was verified. Results: The social deprivation index selected two factors that, together, explained 77.63% of the total variance. The preventable fetal mortality rate increased among strata of social need, with rates of 8.0 per thousand births (low deprivation), 8.1 per thousand (medium deprivation), 8.8 per thousand (high deprivation), and 10.7 per thousand (very high social deprivation). Some municipalities in the São Francisco and Sertão Mesoregions had both high fetal and preventable fetal mortality, in addition to a very high social deprivation rate. Conclusion: The spatial analysis identified areas with the highest risk for fetal mortality. The social deprivation index listed some determinants of fetal deaths in areas with worse living conditions. Priority areas for intervention in public policies to reduce fetal mortality and its determinants were detected.

RESUMO: Objetivo: Elaborar um índice de carência social para a estratificação dos municípios e a identificação de áreas prioritárias para a redução da mortalidade fetal. Métodos: Estudo ecológico, realizado no estado de Pernambuco, entre 2010 e 2017. Utilizou-se a técnica de análise fatorial por componentes principais para a elaboração do índice de carência social. Na análise espacial, aplicou-se o estimador bayesiano empírico local, e verificou-se a autocorrelação espacial de Moran. Resultados: O índice de carência social selecionou dois fatores que, juntos, explicaram 77,63% da variância total. A taxa de mortalidade fetal evitável apresentou aumento entre estratos de carência social, com taxas de 8 por mil nascimentos (baixa carência), 8,1 por mil (média carência), 8,8 por mil (alta carência) e 10,7 por mil (muito alta carência social). Alguns municípios das mesorregiões São Francisco e Sertão tiveram, simultaneamente, elevada mortalidade fetal e fetal evitável, além de índice de carência social muito alto. Conclusão: A análise espacial identificou áreas com maior risco para a mortalidade fetal. O índice de carência social relacionou alguns determinantes das mortes fetais em áreas com piores condições de vida. Detectaram-se áreas prioritárias para a intervenção das políticas públicas de redução da mortalidade fetal e seus determinantes.

Laboratory Studies of Questing Behavior in Colonized Nymphal Amblyomma maculatum Ticks (Acari: Ixodidae).

Environmental factors affect host-seeking behavior in ticks. In this study, 80 nymphal Amblyomma maculatum Koch were released in an observation arena containing four different heights of broomsedge stems (Andropogon virginicus L.) anchored in sand. Observations were made over three days as to proportion of ticks questing, questing height, and stem height distribution This scenario was replicated three times with different cohorts of ticks (n = 80 per replicate) for each of three treatment combinations of temperature and humidity: High temperature/high humidity (HTHH), high temperature/low humidity (HTLH), and low temperature/high humidity (LTHH). A fourth treatment utilizing the same size cohort and number of replicates included Wind (HTHHW+/-) by alternating days of wind and no-wind conditions over four days. Mean questing height for ticks under HTHH, HTLH, and LTHH conditions ranged from 4.45 to 6.03 cm with ticks questing significantly higher in HTHH. A significantly lower proportion ticks quested in HTLH (8.64%) than HTHH (14.06%) and LTHH (15.33%). In HTHH and LTHH, a significantly higher proportion of ticks were observed questing on 5-cm stems. Wind significantly reduced average questing height, and when absent, ticks on 20- and 30-cm stems quested significantly higher. These data indicate that A. macuatum nymphs randomly select stems to quest upon and climb upward until environmental conditions are prohibitive/ideal. Conditions with reduced vapor pressure deficit (VPD) led to higher questing frequency and height. Relatively low questing heights observed correspond with size of preferred hosts and may explain infrequency of collection by dragcloth in the field.

Mean Airway Pressure As a Predictor of 90-Day Mortality in Mechanically Ventilated Patients.

OBJECTIVES: To determine the association between mean airway pressure and 90-day mortality in patients with acute respiratory failure requiring mechanical ventilation and to compare the predictive ability of mean airway pressure compared with inspiratory plateau pressure and driving pressure. DESIGN: Prospective observational cohort. SETTING: Five ICUs in Lima, Peru. SUBJECTS: Adults requiring invasive mechanical ventilation via endotracheal tube for acute respiratory failure. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of potentially eligible participants (n = 1,500), 65 (4%) were missing baseline mean airway pressure, while 352 (23.5%) were missing baseline plateau pressure and driving pressure. Ultimately, 1,429 participants were included in the analysis with an average age of 59 ± 19 years, 45% female, and a mean PaO2/FIO2 ratio of 248 ± 147 mm Hg at baseline. Overall, 90-day mortality was 50.4%. Median baseline mean airway pressure was 13 cm H2O (interquartile range, 10-16 cm H2O) in participants who died compared to a median mean airway pressure of 12 cm H2O (interquartile range, 10-14 cm H2O) in participants who survived greater than 90 days (p < 0.001). Mean airway pressure was independently associated with 90-day mortality (odds ratio, 1.38 for difference comparing the 75th to the 25th percentile for mean airway pressure; 95% CI, 1.10-1.74) after adjusting for age, sex, baseline Acute Physiology and Chronic Health Evaluation III, baseline PaO2/FIO2 (modeled with restricted cubic spline), baseline positive end-expiratory pressure, baseline tidal volume, and hospital site. In predicting 90-day mortality, baseline mean airway pressure demonstrated similar discriminative ability (adjusted area under the curve = 0.69) and calibration characteristics as baseline plateau pressure and driving pressure. CONCLUSIONS: In a multicenter prospective cohort, baseline mean airway pressure was independently associated with 90-day mortality in mechanically ventilated participants and predicts mortality similarly to plateau pressure and driving pressure. Because mean airway pressure is readily available on all mechanically ventilated patients and all ventilator modes, it is a potentially more useful predictor of mortality in acute respiratory failure.