Lack of correlation between central venous minus arterial PCO2 to arterial minus central venous O2 content ratio and respiratory quotient in patients with septic shock: A prospective observational study.

OBJECTIVE: Central venous-arterial PCO2 to arterial-central venous O2 content ratio (Pcv-aCO2/Ca-cvO2) is commonly used as a surrogate for respiratory quotient (RQ) and tissue oxygenation. Although Pcv-aCO2/Ca-cvO2 might be associated with hyperlactatemia and outcome, neither the interchangeability with RQ nor the correlation with conclusive variables of anaerobic metabolism has never been demonstrated in septic shock. Our goal was to compare Pcv-aCO2/Ca-cvO2 and RQ in patients with septic shock. DESIGN: Prospective, observational study. SETTING: Two adult ICUs. PATIENTS: Forty-seven patients with septic shock on mechanical ventilation with stable respiratory settings and vasopressor dose after initial resuscitation. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: We measured arterial and central venous gases, Hb, and O2Hb. Pcv-aCO2/Ca-cvO2 and the ratio of central venous-arterial CO2 content to arterial-central venous O2 content (Ccv-aCO2/Ca-cvO2) were calculated. RQ was determined by indirect calorimetry. RESULTS: Pcv-aCO2/Ca-cvO2 and Ccv-aCO2/Ca-cvO2 were not correlated with RQ (R2 = 0.01, P = 0.50 and R2 = 0.01, P = 0.58, respectively), showing large bias and wide 95 % limits of agreement with RQ (1.09, -1.10-3.27 and 0.42, -1.53-2.37). A multiple linear regression model showed Hb, and central venous PCO2 and O2Hb, but not RQ, as Pcv-aCO2/Ca-cvO2 determinants (R2 = 0.36, P = 0.0007). CONCLUSIONS: In patients with septic shock, Pcv-aCO2/Ca-cvO2 did not correlate with RQ and was mainly determined by factors that modify the dissociation of CO2 from Hb. Pcv-aCO2/Ca-cvO2 seems to be a poor surrogate for RQ; therefore, its values should be interpreted with caution.

Acute atrazine intoxication in heifers: Case report and toxicological studies.

Atrazine is a triazine organochloride herbicide, frequently used in different agricultural activities. Rare acute intoxication with atrazine is reported in production animals, and its metabolism in mammals is unknown. We report a spontaneous case of atrazine acute intoxication in 16.1% animals of a 168-beef heifer herd exposed to the herbicide at a farm located in Buenos Aires province, Argentina. Affected heifers showed different neurological signs and died suddenly, similar to the previous natural atrazine intoxication report. During autopsy, no gross lesions were observed. Different body fluids and tissues samples were collected during postmortem examination. No relevant histopathological findings were observed. High levels of atrazine and its metabolites were detected in different fluids and tissues by ultra-liquid chromatography high performance coupled to triple quadrupole mass spectrometry. These findings suggest ruminal or hepatic metabolization of atrazine in the exposed cattle. This is the first report of quantification and distribution of atrazine and its metabolites in intoxicated mammals providing relevant information for diagnostic purposes.

Calcium complexation by steroids involved in the steroidogenesis.

Steroids that take part in the pathways of human steroidogenesis are involved in many biological mechanisms where they interact with calcium. In the present work, the binding selectivities and affinities for calcium of progestagens, mineralocorticoids, androstagens, and estrogens were studied by Electrospray Ionization-Mass Spectrometry (ESI-MS). The adduct profile of each steroid was characterized by high resolution and tandem mass spectrometry. The relative stability of the most important adducts was studied by threshold collision induced dissociation, E1/2. Doubly-charged steroid-calcium complexes [nM + Ca]2+ with n = 1-6 were predominant in the mass spectra. The adduct [5M + Ca]2+ was the base peak for most 3-keto-steroids, while ligands bearing hindered ketones or α-hydroxy-ketones also yielded [nM + Ca + mH2O]2+ with n = 3-4 and m = 0-1. Principal component analysis allowed us to spot the main differences and similarities in the binding behavior of these steroids. The isomers testosterone and dehydroepiandrosterone, androstanolone and epiandrosterone, and 17-α-hydroxyprogesterone and 11-deoxycorticosterone showed remarkable differences in their adduct profiles. Computational modeling of representative adducts was performed by density functional theory methods. The possible binding modes at low and high numbers of steroid ligands were determined by calcium Gas Phase Affinity, and through modeling of the complexes and comparison of their relative stabilities, in agreement with the experimental results.

Forms of nitrogen inputs regulate the intensity of soil acidification.

Soil acidification induced by reactive nitrogen (N) inputs can alter the structure and function of terrestrial ecosystems. Because different N-transformation processes contribute to the production and consumption of H+ , the magnitude of acidification likely depends on the relative amounts of organic N (ON) and inorganic N (IN) inputs. However, few studies have explicitly measured the effects of N composition on soil acidification. In this study, we first conducted a meta-analysis to test the effects of ON or IN inputs on soil acidification across 53 studies in grasslands. We then compared soil acidification across five different ON:IN ratios and two input rates based on long-term field N addition experiments. The meta-analysis showed that ON had weaker effects on soil acidification than IN when the N addition rate was above 20 g N m-2 year-1 . The field experiment confirmed the findings from meta-analysis: N addition with proportions of ON ≥ 20% caused less soil acidification, especially at a high input rate (30 g N m-2 year-1 ). Structural equation model analysis showed that this result was largely due to a relatively low rate of H+ production from ON as NH3 volatilization and uptake of ON and NH4 + by the dominant grass species Leymus chinensis (which are both lower net contributors to H+ production) result in less NH4 + available for nitrification (which is a higher net contributor to H+ production). These results indicate that the evaluation of soil acidification induced by N inputs should consider N forms and manipulations of relative composition of N inputs may provide an effective approach to alleviate the N-induced soil acidification.

Antifungal γ-Pyrone and Isoprenylated Cyclohexanoids from the Fungus Beenakia informis.

Chemical investigation of the extract of the macroscopic fungus Beenakia informis led to the isolation of a previously unreported γ-pyrone and two new isoprenylated cyclohexanoids, together with speciocin N. Their structures were elucidated spectroscopically and the absolute configuration was determined by comparison of the experimental vs. calculated ECD curves. Three of the compounds showed very good to moderate activity against phytopathogenic fungi.

Scalable Query Answering Under Uncertainty to Neuroscientific Ontological Knowledge: The NeuroLang Approach.

Researchers in neuroscience have a growing number of datasets available to study the brain, which is made possible by recent technological advances. Given the extent to which the brain has been studied, there is also available ontological knowledge encoding the current state of the art regarding its different areas, activation patterns, keywords associated with studies, etc. Furthermore, there is inherent uncertainty associated with brain scans arising from the mapping between voxels-3D pixels-and actual points in different individual brains. Unfortunately, there is currently no unifying framework for accessing such collections of rich heterogeneous data under uncertainty, making it necessary for researchers to rely on ad hoc tools. In particular, one major weakness of current tools that attempt to address this task is that only very limited propositional query languages have been developed. In this paper we present NeuroLang, a probabilistic language based on first-order logic with existential rules, probabilistic uncertainty, ontologies integration under the open world assumption, and built-in mechanisms to guarantee tractable query answering over very large datasets. NeuroLang's primary objective is to provide a unified framework to seamlessly integrate heterogeneous data, such as ontologies, and map fine-grained cognitive domains to brain regions through a set of formal criteria, promoting shareable and highly reproducible research. After presenting the language and its general query answering architecture, we discuss real-world use cases showing how NeuroLang can be applied to practical scenarios.

Functional gradients in the human lateral prefrontal cortex revealed by a comprehensive coordinate-based meta-analysis.

The lateral prefrontal cortex (LPFC) of humans enables flexible goal-directed behavior. However, its functional organization remains actively debated after decades of research. Moreover, recent efforts aiming to map the LPFC through meta-analysis are limited, either in scope or in the inferred specificity of structure-function associations. These limitations are in part due to the limited expressiveness of commonly-used data analysis tools, which restricts the breadth and complexity of questions that can be expressed in a meta-analysis. Here, we adopt NeuroLang, a novel approach to more expressive meta-analysis based on probabilistic first-order logic programming, to infer the organizing principles of the LPFC from 14,371 neuroimaging studies. Our findings reveal a rostrocaudal and a dorsoventral gradient, respectively explaining the most and second most variance in meta-analytic connectivity across the LPFC. Moreover, we identify a unimodal-to-transmodal spectrum of coactivation patterns along with a concrete-to-abstract axis of structure-function associations extending from caudal to rostral regions of the LPFC. Finally, we infer inter-hemispheric asymmetries along the principal rostrocaudal gradient, identifying hemisphere-specific associations with topics of language, memory, response inhibition, and sensory processing. Overall, this study provides a comprehensive meta-analytic mapping of the LPFC, grounding future hypothesis generation on a quantitative overview of past findings.

Cyclic heptapeptides with metal binding properties isolated from the fungus Cadophora malorum from Antarctic soil.

The Antarctic fungus Cadophora malorum produces previously undescribed cyclic heptapeptides (cadophorin A and B) containing an anthranilic acid residue. The planar structure of these peptides was determined by high-resolution mass spectrometry combined with extensive 1D and 2D NMR spectroscopy. The absolute configuration of the amino acids was determined by Marfey's method, with HPLC analysis of FDVA (Nα-(2,4-dinitro-5-fluorphenyl)-L-valinamide) derivatives making use of a PFP column. Remarkably, cadophorin 2 possesses both the uncommon D-Ile and D-allo-Ile in its structure. The peptides have metal binding properties as shown by LCMS with post column addition of metal salt solutions. These results were supported by DFT calculations.

Tana, a Healthcare Chatbot to Help Patients During the COVID-19 Pandemic at a University Hospital in Argentina.

A Chatbot or Conversational Agent is a computer application that simulates the conversation with a human person (by text or voice), giving automated responses to people's needs. In the healthcare domain, chatbots can be beneficial to help patients, as a complement to care by health personnel, especially in times of high demand or constrained resources such as the COVID-19 Pandemic. In this paper we share the design and implementation of a healthcare chatbot called Tana at the Hospital Italiano de Buenos Aires. Considering best practices and being aware of possible unintended consequences, we must take advantage of information and communication technologies, such as chatbots, to analyze and promote useful conversations for the health of all people.

Wing osteology, myology, and function of Rhea americana (Aves, Rheidae).

The Greater Rhea (Rhea americana, Rheidae) is a flightless paleognath with a wide geographical distribution in South America. The morphology of its shoulder girdle and wings are different from those of flying birds and some characteristics are similar to basal birds and paravian theropods. We present a detailed osteological, myological, and functional study of the shoulder and the wing of the Greater Rhea. Particular features of the anatomy of the pectoral girdle and wing of Rhea include the lack of triosseal canal, reduced origin area of the mm. pectoralis p. thoracica and supracoracoideus and the lack of a propatagium. The wing muscle mass is markedly reduced, reaching only 0.89% of total body mass (BM). Forelimb muscles mass values are low compared to those of flying birds and are congruent with the non-use of wings for active locomotion movements. R. americana does not flap the wings dorso-ventral as typical for flying birds, but predominantly in cranio-caudal direction, following a craniolateral to caudomedial abduction-adduction arc. When the wings are fully abducted, they are inverted L-shaped, with the inner surface caudally faced, and when the wings are folded against the body, they do not perform the complete automatic wing folding nor the circumduction of the manus, a movement performed by extant volant birds. This study complements our knowledge of the axial musculature of the flightless paleognaths and highlights the use of the Greater Rhea as a model, which may help understand the evolution of Palaeognathae, as well as the origin of flapping flight among paravian theropods.

Modelling COVID-19 incidence in the African sub-region using smooth transition autoregressive model.

Prediction of COVID-19 incidence and transmissibility rates are essential to inform disease control policy and allocation of limited resources (especially to hotspots), and also to prepare towards healthcare facilities demand. This study demonstrates the capabilities of nonlinear smooth transition autoregressive (STAR) model for improved forecasting of COVID-19 incidence in the Africa sub-region were investigated. Data used in the study were daily confirmed new cases of COVID-19 from February 25 to August 31, 2020. The results from the study showed the nonlinear STAR-type model with logistic transition function aptly captured the nonlinear dynamics in the data and provided a better fit for the data than the linear model. The nonlinear STAR-type model further outperformed the linear autoregressive model for predicting both in-sample and out-of-sample incidence.

Geographically weighted principal component analysis for characterising the spatial heterogeneity and connectivity of soil heavy metals in Kumasi, Ghana.

The use of principal component analysis (PCA) for soil heavy metals characterization provides useful information for decision making and policies regarding the potential sources of soil contamination. However, the concentration of heavy metal pollutants is spatially heterogeneous. Accounting for such spatial heterogeneity in soil heavy metal pollutants will improve our understanding with respect to the distribution of the most influential soil heavy metal pollutants. In this study, geographically weighted principal component analysis (GWPCA) was used to describe the spatial heterogeneity and connectivity of soil heavy metals in Kumasi, Ghana. The results from the conventional PCA revealed that three principal components cumulatively accounted for 86% of the total variation in the soil heavy metals in the study area. These components were largely dominated by Fe and Zn. The results from the GWPCA showed that the soil heavy metals are spatially heterogeneous and that the use of PCA disregards this considerable variation. This spatial heterogeneity was confirmed by the spatial maps constructed from the geographically weighted correlations among the variables. After accounting for the spatial heterogeneity, the proportion of variance explained by the three geographically weighted principal components ranged between 85% and 89%. The first three identified GWPC were largely dominated by Fe, Zn and As, respectively. The location of the study area where these variables are dominated provides information for remediation.

The effects of weather on the spread of COVID-19: evidence from Ghana.

BACKGROUND: Climatic factors have been shown to influence communicable disease dynamics especially in tropical regions where temperature could swing from extreme heat and dryness to wet and cold within a short period of time. This is more pronounced in the spread of airborne diseases. In this study, the effect of some local weather variables (average temperature, average relative humidity, average wind speed and average atmospheric pressure) on the risk of Severe Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Ghana is investigated. The daily confirmed new COVID-19 cases were compiled from the Ghana Health Service and the weather data extracted from Weatherbase. The type of relationship between the climatic variable and risk of spread were explored using the Generalized Additive Model (GAM). RESULTS: Results obtained showed that wind speed and atmospheric pressure have positive linear relationship with the spread of infection an increase in the risk of COVID-19 spread. In addition, the risk of spread fluctuates for temperature between 24 and 29 °C but sharply decreases when average temperature exceeds 29 °C. The risk of spread of COVID-19 significantly decrease for relative humidity between 72 and 76% and leveled afterwards. CONCLUSION: The results indicate that wind speed and pressure have a positive linear relationship with the risk of spread of COVID-19 whilst temperature and humidity have a non-linear relationship with the spread of COVID-19. These findings highlight the need for policy makers to design effective countermeasures for controlling the spread as we are still within the low temperature season.

Effect of leaf-to-fruit ratios on phenolic and sensory profiles of Malbec wines from single high-wire-trellised vineyards.

BACKGROUND: The single high-wire system is a free canopy trellis system suitable for warm to hot climates. In a global warming scenario, it arouses as a technological solution since it prevents berry overheating and sunburn. Canopy management practices manipulate leaf-to-fruit ratios, affecting berry and wine composition. We aimed to evaluate the phenolic and sensory profiles of Malbec wines from single high-wire trellised vineyards in a hot region in Mendoza (Argentina) and to assess the effect of varying leaf-to-fruit ratios on these attributes. We manipulated leaf-to-fruit ratios by varying shoot trimming (experiment 1: 0.45 m, 0.80 m, and untrimmed) and winter pruning severity (experiment 2: 16, 24, 32, and >32 countable buds per meter). We characterized wine attributes by a descriptive analysis, color by the CIELAB space, and global phenolics compounds and anthocyanins by high-performance liquid chromatography with diode array detection. RESULTS: We found that wines where shoots were trimmed to 0.80 m or left untrimmed had similar and greater intensity of color, violet hue, astringency, and alcohol and a richer aroma profile than wines where shoots were trimmed to 0.45 m. Meanwhile, wines from 16 and >32 buds/m treatments (the latter simulating a box pruning) were similar to each other and had higher color intensity, violet hue, acidity, alcohol, and astringency and a more complex aroma profile than the other pruning treatments. CONCLUSIONS: The best quality wines were achieved by leaving 16 or >32 buds/m and by trimming shoots to 0.80 m or leaving them untrimmed. The modulation of cultural practices in sprawling canopies offers the potential to produce wines with different styles in hot regions. © 2020 Society of Chemical Industry.

Lanostanoid triterpenes from the fungus Rigidoporus microporus.

Five new lanostanoid triterpenes were isolated from the extract of R. microporus. Three of the metabolites (1-3) present a Δ8,9 skeleton with an uncommon keto functionality at C-1. Another compound (4) has an unprecedented rearranged skeleton in which methyl-19 was transposed to C-1, with conjugated double bonds at Δ1-10 and Δ8-9. All of the compounds have hydroxylated or furane-cyclized side-chains. The structures were elucidated by spectroscopic methods, and the absolute configuration of the hydroxyl-bearing carbon in the side chain of compound 5 was established in silico. The metabolites were evaluated for their antifungal activity and the bioactivity as agonist/antagonists of the liver X receptors (LXRs). Compound 4 presents antifungal activity and compounds 3 and 5 are the agonists of LXRs.

Acute renal failure in children. Multicenter prospective cohort study in medium-complexity intensive care units from the Colombian southeast.

BACKGROUND: Acute kidney injury is frequent in critically ill children; however, it varies in causality and epidemiology according to the level of patient care complexity. A multicenter prospective cohort study was conducted in four medium-complexity pediatric intensive care units from the Colombian southeast aimed to estimate the clinical prognosis of patients with diagnosis of acute kidney injury. METHODS: We included children >28 days and <18 years of age, who were admitted with diagnosis of acute kidney injury classified by Kidney Disease Improving Global Outcomes (KDIGO), during the period from January to December 2017. Severe acute kidney injury was defined as stage 2 and stage 3 classifications. Maximum KDIGO was evaluated during the hospital stay and follow up. Length of hospital stay, use of mechanical ventilation and vasoactive drugs, use of renal replacement therapy, and mortality were assessed until discharge. RESULTS: Prevalence at admission of acute kidney injury was 5.2% (95%CI 4.3% to 6.2%). It was found that 71% of the patients had their maximum KDIGO on day one; an increment in the maximum stage of acute kidney injury increased the pediatric intensive care unit stay. Patients with maximum KDIGO 3 were associated with greater use of mechanical ventilation (47%), compared with maximum KDIGO 2 (37%) and maximum KDIGO 1 (16%). Eight patients with maximum KDIGO 2 and 14 with maximum KDIGO 3 required renal replacement therapy. Mortality was at 11.8% (95%CI 6.4% to 19.4%). CONCLUSION: Acute kidney injury, established and classified according to KDIGO as severe and its maximum stage, was associated with worse clinical outcomes; early therapeutic efforts should focus on preventing the progression to severe stages.

Quantifying nutrient recovery efficiency and loss from compost-based urban agriculture.

The use of compost in urban agriculture offers an opportunity to increase nutrient recycling in urban ecosystems, but recent studies have shown that compost application often results in phosphorus (P) being applied far in excess of crop nutrient demand, creating the potential for P loss through leachate and runoff. Management goals such as maximizing crop yields or maximizing the mass of nutrients recycled from compost may inadvertently result in P loss, creating a potential ecosystem disservice. Here, we report the results from the first two years of an experimental study in which four different crops grown in raised-bed garden plots with high background P and organic matter received one of two types of compost (municipal compost made from urban organics waste, or manure-based compost) at two different levels (applied based on crop N or P demand), while additional treatments received synthetic N and P fertilizer or no soil amendments. Because of the low N:P ratio of compost relative to crop nutrient uptake, compost application based on crop N demand resulted in overapplication of P. Crop yield did not differ among treatments receiving compost inputs, and the mass of P recovered in crops relative to P inputs decreased for treatments with higher compost application rates. Treatments receiving compost targeted to crop N demand had P leachate rates approximately twice as high as other treatments. These results highlight tradeoffs inherent in recycling nutrients through UA, but they also show that targeted compost application rates have the capacity to maintain crop yields while minimizing nutrient loss. UA has the potential to help close the urban nutrient loop, but if UA is to be scaled up in order to maximize potential social, economic, and environmental benefits, it is especially important to carefully manage nutrients to avoid ecosystem disservices from nutrient pollution.

The genus Obrium Dejean, 1821 (Coleoptera: Cerambycidae: Cerambycinae: Obriini) in Argentina: new species, distributions and host plant.

The following species of the genus Obrium Dejean, 1821 are currently listed for Argentina: O. bifasciatum Martins and Galileo, 2003; O. cantharinum cantharinum (Linnaeus, 1767); O. cicatricosum Gounelle, 1909; O. multifarium Berg, 1889; O. trifasciatum Bosq, 1951; O. vicinum Gounelle, 1909. Two new species are described: O. mimicum and O. trilobatum. The species are illustrated; a key to species of the genus occurring in Argentina is provided. The geographic distribution and the host plants in the country are mentioned.

MÉTODOS MICROBIOLÓGICOS ALTERNATIVOS: REVISIÓN DEL PROCESO DE VALIDACIÓN PARA LA IMPLEMENTACIÓN EN LA INDUSTRIA FARMACÉUTICA / Alternatives microbiological methods: review of the validation process for the implementation in the pharmaceutical industry

Los métodos clásicos o tradicionales utilizados para el control microbiológico de medicamentos fueron desarrollados hace más de un siglo y se continúan utilizando ya que cumplen con su función de enumerar e identificar microorganismos, contribuyendo a controlar la seguridad microbiológica de los productos farmacéuticos. Estos métodos, tienen la principal desventaja de requerir prolongados tiempos de incubación por lo que, con la intención de resolver este punto y otras limitaciones, se desarrollaron nuevas tecnologías con distintas estrategias para la detección microbiana. El objetivo del presente trabajo fue analizar y discutir acerca de los procesos de validación de métodos microbiológicos alternativos y su implementación en el control de calidad de productos farmacéuticos. Las tecnologías utilizadas en los métodos microbiológicos alternativos pueden clasificarse en detección temprana basada en la actividad metabólica, medición directa de células, o basados en la medición de biomoléculas. Los parámetros críticos a evaluar son exactitud, precisión, especificidad, límite de detección y cuantificación, linealidad y rango, robustez y equivalencia; su determinación dependerá de la categoría del ensayo: cualitativo/cuantitativo. Las guías analizadas presentan lineamientos generales sobre el análisis de estos atributos, evidenciándose leves diferencias en la terminología, procedimientos de validación, interpretación de datos, criterios de aceptación y uso de métodos estadísticos. Según surge de la revisión realizada, se destaca el requisito de contar con procedimientos de ensayo detallados, con el fin de establecer los atributos de validación para productos farmacéuticos

The traditional methods used for the microbiological quality control of medicines were developed more than a century ago and they continue being used since they fulfill the role to enumerate and identify microorganisms, providing microbiological safety of pharmaceutical products. These methods have the main disadvantage of requiring long incubation times, therefore, with the intention of solving this point and other limitations, new technologies were developed. The objective of this work was to analyze and discuss the validation processes of alternative microbiological methods and their implementation in the quality control of pharmaceutical products. The technologies used in alternative microbiological methods can be classified as: early detection based on metabolic activity, direct measurement of cells, or based on the measurement of biomolecules. The critical parameters to evaluate are accuracy, precision, specificity, limit of detection and quantification, linearity and range, robustness and equivalence; its determination will depend on the category of the assay: qualitative / quantitative. The consulted bibliography presents general guidelines on the analysis of these attributes, showing slight differences in terminology, validation procedures, data interpretation, acceptance criteria and use of statistical methods. To summarize, this review highlights the importance of using detailed test procedures, in order to establish the validation attributes for pharmaceutical products.

Wing and tail myology of Tyto furcata (Aves, Tytonidae).

Barn Owls (Tytonidae) are nocturnal raptors with the largest geographical distribution among Strigiformes. Several osteological, morphometrical, and biomechanical studies of this species were performed by previous authors. Nevertheless, the myology of forelimb and tail of the Barn Owls is virtually unknown. This study is the first detailed myological study performed on the wing and tail of the American Barn Owl (Tyto furcata). A total of 11 specimens were dissected and their morphology and muscle masses were described. Although T. furcata has the wing and tail myological pattern present in other species of Strigiformes, some peculiarities were observed including a difference in the attachment of m. pectoralis propatagialis due to the lack of the os prominence, and the presence of an osseous arch in the radius that seems to widen the anchorage area of the mm. pronator profundus, extensor longus alulae, and extensor longus digiti majoris. Furthermore, the m. biceps brachii has an unusual extra belly that flexes the forearm. The interosseous muscles have a small size and lacks ossified tendons. This feature may be indicative of a lower specialization in the elevation and flexion of the digiti majoris. Forelimb and tail muscle mass account for 10.66 and 0.24% of the total body mass, respectively. Forelimb muscle mass value is similar to the nocturnal (Strigiformes) and diurnal (Falconidae and Accipitridae) raptors, while the tail value is lower than in the diurnal raptors (Falconidae and Accipitridae). The myological differences with other birds of prey are here interpreted in association with their "parachuting" hunting style. This work complements our knowledge of the axial musculature of the American Barn owls, and provides important information for future studies related to functional morphology and ecomorphology.