An organic O donor for biological hydroxylation reactions.

All biological hydroxylation reactions are thought to derive the oxygen atom from one of three inorganic oxygen donors, O2, H2O2, or H2O. Here, we have identified the organic compound prephenate as the oxygen donor for the three hydroxylation steps of the O2-independent biosynthetic pathway of ubiquinone, a widely distributed lipid coenzyme. Prephenate is an intermediate in the aromatic amino acid pathway and genetic experiments showed that it is essential for ubiquinone biosynthesis in Escherichia coli under anaerobic conditions. Metabolic labeling experiments with 18O-shikimate, a precursor of prephenate, demonstrated the incorporation of 18O atoms into ubiquinone. The role of specific iron-sulfur enzymes belonging to the widespread U32 protein family is discussed. Prephenate-dependent hydroxylation reactions represent a unique biochemical strategy for adaptation to anaerobic environments.

Anaerobic respiration of host-derived methionine sulfoxide protects intracellular Salmonella from the phagocyte NADPH oxidase.

Intracellular Salmonella experiencing oxidative stress downregulates aerobic respiration. To maintain cellular energetics during periods of oxidative stress, intracellular Salmonella must utilize terminal electron acceptors of lower energetic value than molecular oxygen. We show here that intracellular Salmonella undergoes anaerobic respiration during adaptation to the respiratory burst of the phagocyte NADPH oxidase in macrophages and in mice. Reactive oxygen species generated by phagocytes oxidize methionine, generating methionine sulfoxide. Anaerobic Salmonella uses the molybdenum cofactor-containing DmsABC enzymatic complex to reduce methionine sulfoxide. The enzymatic activity of the methionine sulfoxide reductase DmsABC helps Salmonella maintain an alkaline cytoplasm that supports the synthesis of the antioxidant hydrogen sulfide via cysteine desulfuration while providing a source of methionine and fostering redox balancing by associated dehydrogenases. Our investigations demonstrate that nontyphoidal Salmonella responding to oxidative stress exploits the anaerobic metabolism associated with dmsABC gene products, a pathway that has accrued inactivating mutations in human-adapted typhoidal serovars.

Elevated concentrations of polymyxin B elicit a biofilm-specific resistance mechanism in Vibrio cholerae.

Vibrio cholerae can form biofilms in the aquatic environment and in the human intestine, facilitating the release of hyper-infectious aggregates. Due to the increasing antibiotic resistance, alternatives need to be found. One of these alternatives is antimicrobial peptides, including polymyxin B (PmB). In this study, we first investigated the resistance of V. cholerae O1 El Tor strain A1552 to various antimicrobials under aerobic and anaerobic conditions. An increased resistance to PmB is observed in anaerobiosis, with a 3-fold increase in the dose required for 50 % growth inhibition. We then studied the impact of the PmB on the formation and the degradation of V. cholerae biofilms to PmB. Our results show that PmB affects more efficiently biofilm formation under anaerobic conditions. On the other hand, preformed biofilms are susceptible to degradation by PmB at concentrations close to the minimal inhibitory concentration. At higher concentrations, we observe an opacification of the biofilm structures within 20 min post-treatment, suggesting a densification of the structure. This densification does not seem to result from the overexpression of matrix genes but rather from DNA release through massive cell lysis, likely forming a protective shield that limits the penetration of the PmB into the biofilm.

Anaeramoeba pumila sp. nov. and Anaeramoeba sp. OCE22C represent two novel types of symbiosis of Anaeramoebae and prokaryotes.

Anaeramoebae is a recently described phylum of anaerobic, marine amoebae, and amoeboflagellates belonging to the Metamonada supergroup. So far, six species have been described based on light microscopic morphology and sequences of the SSU rRNA gene. Here we present three new strains of Anaeramoeba with a description of their morphology, ultrastructure, and phylogenetic position based on the analysis of SSU rRNA gene sequences. Two of the strains represent a new species, Anaeramoeba pumila sp. nov., that has the smallest cells of all known Anaeramoeba species, and one that represents a species from the newly recognized Anaeramoeba flamelloides complex. Anaeramoebae are known to have a syntrophic relationship with prokaryotes. Our strains display two novel, remarkable types of symbioses, previously unknown from Anaeramoebae.

Soft-metal(loid)s induce protein aggregation in Escherichia coli.

Metal(loid) salts were used to treat infectious diseases in the past due to their exceptional biocidal properties at low concentrations. However, the mechanism of their toxicity has yet to be fully elucidated. The production of reactive oxygen species (ROS) has been linked to the toxicity of soft metal(loid)s such as Ag(I), Au(III), As(III), Cd(II), Hg(II), and Te(IV). Nevertheless, few reports have described the direct, or ROS-independent, effects of some of these soft-metal(loid)s on bacteria, including the dismantling of iron-sulfur clusters [4Fe-4S] and the accumulation of porphyrin IX. Here, we used genome-wide genetic, proteomic, and biochemical approaches under anaerobic conditions to evaluate the direct mechanisms of toxicity of these metal(loid)s in Escherichia coli. We found that certain soft-metal(loid)s promote protein aggregation in a ROS-independent manner. This aggregation occurs during translation in the presence of Ag(I), Au(III), Hg(II), or Te(IV) and post-translationally in cells exposed to Cd(II) or As(III). We determined that aggregated proteins were involved in several essential biological processes that could lead to cell death. For instance, several enzymes involved in amino acid biosynthesis were aggregated after soft-metal(loid) exposure, disrupting intracellular amino acid concentration. We also propose a possible mechanism to explain how soft-metal(loid)s act as proteotoxic agents.

The divergent ER-mitochondria encounter structures (ERMES) are conserved in parabasalids but lost in several anaerobic lineages with hydrogenosomes.

BACKGROUND: The endoplasmic reticulum (ER)-mitochondria membrane contact sites (MCS) are extensively studied in aerobic eukaryotes; however, little is known about MCS in anaerobes with reduced forms of mitochondria named hydrogenosomes. In several eukaryotic lineages, the direct physical tether between ER and the outer mitochondrial membrane is formed by ER-mitochondria encounter structure (ERMES). The complex consists of four core proteins (Mmm1, Mmm2, Mdm12, and Mdm10) which are involved in phospholipid trafficking. Here we investigated ERMES distribution in organisms bearing hydrogenosomes and employed Trichomonas vaginalis as a model to estimate ERMES cellular localization, structure, and function. RESULTS: Homology searches revealed that Parabasalia-Anaeramoebae, anaerobic jakobids, and anaerobic fungi are lineages with hydrogenosomes that retain ERMES, while ERMES components were gradually lost in Fornicata, and are absent in Preaxostyla and Archamoebae. In T. vaginalis and other parabasalids, three ERMES components were found with the expansion of Mmm1. Immunofluorescence microscopy confirmed that Mmm1 localized in ER, while Mdm12 and Mmm2 were partially localized in hydrogenosomes. Pull-down assays and mass spectrometry of the ERMES components identified a parabasalid-specific Porin2 as a substitute for the Mdm10. ERMES modeling predicted a formation of a continuous hydrophobic tunnel of TvMmm1-TvMdm12-TvMmm2 that is anchored via Porin2 to the hydrogenosomal outer membrane. Phospholipid-ERMES docking and Mdm12-phospholipid dot-blot indicated that ERMES is involved in the transport of phosphatidylinositol phosphates. The absence of enzymes involved in hydrogenosomal phospholipid metabolism implies that ERMES is not involved in the exchange of substrates between ER and hydrogenosomes but in the unidirectional import of phospholipids into hydrogenosomal membranes. CONCLUSIONS: Our investigation demonstrated that ERMES mediates ER-hydrogenosome interactions in parabasalid T. vaginalis, while the complex was lost in several other lineages with hydrogenosomes.

Anaerobiosis, a neglected factor in phage-bacteria interactions.

IMPORTANCE: Many parameters affect phage-bacteria interaction. Some of these parameters depend on the environment in which the bacteria are present. Anaerobiosis effect on phage infection in facultative anaerobic bacteria has not yet been studied. The absence of oxygen triggers metabolic changes in facultative bacteria and this affects phage infection and viral life cycle. Understanding how an anaerobic environment can alter the behavior of phages during infection is relevant for the phage therapy success.

Fungal Biodeterioration and Preservation of Miniature Artworks.

The study of biodeterioration is an important issue to allow the best conservation and prevent the decay of cultural heritage and artworks. In Naples (Italy), a particular museum (Museodivino) preserves the miniature artworks representing Dante's Divine Comedy and Nativity scenes, executed with organic-based materials in walnut and clay shells. Since they showed putative signs of biodeterioration, the first aim of this study was to verify the presence of microbial colonization. A culture-dependent approach and molecular biology allowed us to isolate and identify the sole fungal strain Aspergillus NCCD (Nativity and Dante's Divine Comedy) belonging to the A. sydowii sub-clade. Based on this result, a sustainable and eco-friendly approach was applied to find a method to preserve the miniature artwork by contrasting the growth of the strain NCCD. Several essential oils used as a natural biocide were tested against Aspergillus strain NCCD belonging to the A. sydowii subclade to determine their potential antimicrobial activity. Results revealed that basil, cloves, fennel, and thyme essential oils exerted antifungal activity, although their effect depended also on the concentration used. Moreover, anoxic treatment and the control of the relative humidity were used in the presence of thyme, in vitro, and in vivo assays to define the impact on fungal growth. No fungal development was detected in vivo in the shells treated with thyme essential oil at high relative humidity after 60 days of incubation at 28 °C. These results highlighted that although relative humidity was the major factor affecting the development of the strain Aspergillus NDDC, the application of thyme in an anaerobic environment is essential in contrasting the fungal growth. Identifying the biodeterioration agent allowed us to plan an eco-friendly, non-destructive approach to be successfully used to guarantee the conditions suitable for conserving miniature artwork.

Comparative analysis of mitochondrion-related organelles in anaerobic amoebozoans.

Archamoebae comprises free-living or endobiotic amoebiform protists that inhabit anaerobic or microaerophilic environments and possess mitochondrion-related organelles (MROs) adapted to function anaerobically. We compared in silico reconstructed MRO proteomes of eight species (six genera) and found that the common ancestor of Archamoebae possessed very few typical components of the protein translocation machinery, electron transport chain and tricarboxylic acid cycle. On the other hand, it contained a sulphate activation pathway and bacterial iron-sulphur (Fe-S) assembly system of MIS-type. The metabolic capacity of the MROs, however, varies markedly within this clade. The glycine cleavage system is widely conserved among Archamoebae, except in Entamoeba, probably owing to its role in catabolic function or one-carbon metabolism. MRO-based pyruvate metabolism was dispensed within subgroups Entamoebidae and Rhizomastixidae, whereas sulphate activation could have been lost in isolated cases of Rhizomastix libera, Mastigamoeba abducta and Endolimax sp. The MIS (Fe-S) assembly system was duplicated in the common ancestor of Mastigamoebidae and Pelomyxidae, and one of the copies took over Fe-S assembly in their MRO. In Entamoebidae and Rhizomastixidae, we hypothesize that Fe-S cluster assembly in both compartments may be facilitated by dual localization of the single system. We could not find evidence for changes in metabolic functions of the MRO in response to changes in habitat; it appears that such environmental drivers do not strongly affect MRO reduction in this group of eukaryotes.

An easy method for quantification of anaerobic and microaerobic gene expression with fluorescent reporter proteins.

Fluorescent proteins, such as green fluorescent proteins, are invaluable tools for detecting and quantifying gene expression in high-throughput reporter gene assays. However, they introduce significant inaccuracies in studies involving microaerobiosis or anaerobiosis, as oxygen is required for the maturation of these proteins' chromophores. In this study, the authors highlight the errors incurred by using fluorescent proteins under limited oxygenation by comparing standard fluorescence-based reporter gene assays to quantitative real-time PCR data in the study of a complex oxygen-regulated gene network. Furthermore, a solution to perform quantification of anaerobic and microaerobic gene expression with fluorescent reporter proteins using a microplate reader with an oxygen control system and applying pulses of full oxygenation before fluorescence measurements is provided.

Lack of change in the respiratory quotient during oxygen supply dependence in endotoxemic shock: a subanalysis of an experimental controlled study / Ausência de alteração no quociente respiratório durante a dependência do suprimento de oxigênio no choque endotoxêmico: subanálise de um estudo experimental controlado

ABSTRACT Objective: To evaluate if the reductions in systemic and renal oxygen consumption are associated with the development of evidence of anaerobic metabolism. Methods: This is a subanalysis of a previously published study. In anesthetized and mechanically ventilated sheep, we measured the respiratory quotient by indirect calorimetry and its systemic, renal, and intestinal surrogates (the ratios of the venous-arterial carbon dioxide pressure and content difference to the arterial-venous oxygen content difference. The Endotoxemic Shock Group (n = 12) was measured at baseline, after 60 minutes of endotoxemic shock, and after 60 and 120 minutes of fluid and norepinephrine resuscitation, and the values were compared with those of a Control Group (n = 12) without interventions. Results: Endotoxemic shock decreased systemic and renal oxygen consumption (6.3 [5.6 - 6.6] versus 7.4 [6.3 - 8.5] mL/minute/kg and 3.7 [3.3 - 4.5] versus 5.4 [4.6 - 9.4] mL/minute/100g; p < 0.05 for both). After 120 minutes of resuscitation, systemic oxygen consumption was normalized, but renal oxygen consumption remained decreased (6.3 [5.9 - 8.2] versus 7.1 [6.1 - 8.6] mL/minute/100g; p = not significance and 3.8 [1.9 - 4.8] versus 5.7 [4.5 - 7.1]; p < 0.05). The respiratory quotient and the systemic, renal and intestinal ratios of the venous-arterial carbon dioxide pressure and content difference to the arterial-venous oxygen content difference did not change throughout the experiments. Conclusion: In this experimental model of septic shock, oxygen supply dependence was not associated with increases in the respiratory quotient or its surrogates. Putative explanations for these findings are the absence of anaerobic metabolism or the poor sensitivity of these variables in detecting this condition.

RESUMO Objetivo: Avaliar se as reduções do consumo de oxigênio sistêmico e renal estão associadas ao desenvolvimento de evidências de metabolismo anaeróbico. Métodos: Esta é uma subanálise de estudo já publicado. Em ovinos anestesiados e ventilados mecanicamente, medimos o quociente respiratório por calorimetria indireta e seus substitutos sistêmicos, renais e intestinais (as razões entre a diferença de pressão venoarterial do teor de dióxido de carbono e a diferença arteriovenosa do teor de oxigênio). O Grupo Choque Endotoxêmico (n = 12) foi medido inicialmente, após 60 minutos do choque endotoxêmico e após 60 e 120 minutos da ressuscitação com fluidos e norepinefrina, e os valores foram comparados com os do Grupo Controle (n = 12) sem intervenções. Resultados: O choque endotoxêmico diminuiu o consumo de oxigênio sistêmico e renal (6,3 [5,6 - 6,6] versus 7,4 [6,3 - 8,5] mL/minuto/kg e 3,7 [3,3 - 4,5] versus 5,4 [4,6 - 9,4] mL/minuto/100g; p < 0,05 para ambos). Após 120 minutos de ressuscitação, o consumo sistêmico de oxigênio foi normalizado, mas o consumo renal de oxigênio permaneceu reduzido (6,3 [5,9 - 8,2] versus 7,1 [6,1 - 8,6] mL/minuto/100g; p = NS e 3,8 [1,9 - 4,8] versus 5,7 [4,5 - 7,1]; p < 0,05). O quociente respiratório e as razões sistêmica, renal e intestinal entre a diferença na pressão venoarterial do teor de dióxido de carbono e a diferença arteriovenosa do teor de oxigênio não se alteraram ao longo dos experimentos. Conclusão: Nesse modelo experimental de choque séptico, a dependência do suprimento de oxigênio não foi associada a aumentos no quociente respiratório ou em seus substitutos. As explicações possíveis para esses achados são a ausência de metabolismo anaeróbico ou a baixa sensibilidade dessas variáveis na detecção dessa condição.

The global anaerobic metabolism regulator fnr is necessary for the degradation of food dyes and drugs by Escherichia coli.

IMPORTANCE: This work has broad relevance due to the ubiquity of dyes containing azo bonds in food and drugs. We report that azo dyes can be degraded by human gut bacteria through both enzymatic and nonenzymatic mechanisms, even from a single gut bacterial species. Furthermore, we revealed that environmental factors, oxygen, and L-Cysteine control the ability of E. coli to degrade azo dyes due to their impacts on bacterial transcription and metabolism. These results open up new opportunities to manipulate the azoreductase activity of the gut microbiome through the manipulation of host diet, suggest that azoreductase potential may be altered in patients suffering from gastrointestinal disease, and highlight the importance of studying bacterial enzymes for drug metabolism in their natural cellular and ecological context.

Anaerocyclidiidae fam. nov. (Oligohymenophorea, Scuticociliatia): A newly recognized major lineage of anaerobic ciliates hosting prokaryotic symbionts.

The research on anaerobic ciliates, to date, has mainly been focused on representatives of obligately anaerobic classes such as Armophorea or Plagiopylea. In this study, we focus on the anaerobic representatives of the subclass Scuticociliatia, members of the class Oligohymenophorea, which is mainly composed of aerobic ciliates. Until now, only a single anaerobic species, Cyclidium porcatum (here transferred to the genus Anaerocyclidium gen. nov.), has been described both molecularly and morphologically. Our broad sampling of anoxic sediments together with cultivation and single cell sequencing approaches have shown that scuticociliates are common and diversified in anoxic environments. Our results show that anaerobic scuticociliates represent a distinctive evolutionary lineage not closely related to the family Cyclidiidae (order Pleuronematida), as previously suggested. However, the phylogenetic position of the newly recognized lineage within the subclass Scuticociliatia remains unresolved. Based on molecular and morphological data, we establish the family Anaerocyclidiidae fam. nov. to accommodate members of this clade. We further provide detailed morphological descriptions and 18S rRNA gene sequences for six new Anaerocyclidium species and significantly broaden the described diversity of anaerobic scuticociliates.

Allometric Scaling of Anaerobic Capacity Estimated from a Unique Field-Based Data Set of Fish Swimming.

AbstractLocomotion is a defining characteristic that can dictate many aspects of an organism's life history in the pursuit of maximizing fitness, including escaping predators, capturing prey, and transitioning between habitats. Exhaustive exercise can have negative consequences for both short-term and long-term energetics and life history trade-offs, influencing fish survival and reproduction. Studies of swimming performance and exhaustive exercise in fish are often conducted on individual species, but few multispecies analyses exist and even fewer in field settings. In fish, swimming performance and exercise have historically been studied in the laboratory using swim tunnels, but an increasing body of work in recreational fisheries science provides a novel way to examine swimming capacity and exhaustion. Using fight time, the time it takes for a hooked fish to be landed on rod and reel fishing gear, as an opportunistic proxy for fish exhaustion, a multispecies meta-analysis of data from studies on recreational fisheries was conducted to elucidate the factors that most influence capacity for exhaustive exercise. Data from 39 species of freshwater and marine fish were aggregated, and negative binomial mixed effects models as well as phylogenetic least squares regression were used to identify the factors that most influenced exhaustive exercise in the field. Fish total length, aspect ratio of the caudal fin, and body form were significant factors in explaining the capacity for exhaustive exercise. Large migratory fish with high aspect ratios were able to fight, and therefore exercise, the longest. These results illustrate that body form and physiology are both deeply intertwined to inform function across fish species and point to angling fight time as a useful approximation of fish swimming capabilities that can be further developed for understanding the limits of fish exercise physiology.

Role of Pv-aCO2 gradient and Pv-aCO2/Ca-vO2 ratio during cardiac surgery: a retrospective observational study.

INTRODUCTION: Arterial lactate, mixed venous O2 saturation, venous minus arterial CO2 partial pressure (Pv-aCO2) and the ratio between this gradient and the arterial minus venous oxygen content (Pv-aCO2/Ca-vO2) were proposed as markers of tissue hypoperfusion and oxygenation. The main goals were to characterize the determinants of Pv-aCO2 and Pv-aCO2/Ca-vO2, and the interchangeability of the variables calculated from mixed and central venous samples. METHODS: 35 cardiac surgery patients were included. Variables were measured or calculated: after anesthesia induction (T1), end of surgery (T2), and at 6...8.ßhours intervals after ICU admission (T3 and T4). RESULTS: Macrohemodynamics was characterized by increased cardiac index and low systemic vascular resistances after surgery (p.ß<.ß0.05). Hemoglobin, arterial-pH, lactate, and systemic O2 metabolism showed significant changes during the study (p.ß<.ß0.05). Pv-aCO2 remained high and without changes, Pv-aCO2/Ca-vO2 was also high and decreased at T4 (p.ß<.ß0.05). A significant correlation was observed globally and at each time interval, between Pv-aCO2 or Pv-aCO2/Ca-vO2 with factors that may affect the CO2 hemoglobin dissociation. A multilevel linear regression model with Pv-aCO2 and Pv-aCO2/Ca-vO2 as outcome variables showed a significant association for Pv-aCO2 with SvO2, and BE (p.ß<.ß0.05), while Pv-aCO2/Ca-vO2 was significantly associated with Hb, SvO2, and BE (p.ß<.ß0.05) but not with cardiac output. Measurements and calculations from mixed and central venous blood were not interchangeable. CONCLUSIONS: Pv-aCO2 and Pv-aCO2/Ca-vO2 could be influenced by different factors that affect the CO2 dissociation curve, these variables should be considered with caution in cardiac surgery patients. Finally, central venous and mixed values were not interchangeable.

Chaperone proteins: universal roles in surviving environmental stress.

Chaperone proteins have crucial roles to play in all animal species and are involved in mediating both the folding of newly synthesized peptides into their mature conformation, the refolding of misfolded proteins, and the trafficking of proteins between subcellular compartments. These highly conserved proteins have particularly important roles to play in dealing with disruptions of the proteome as a result of environmental stress since abiotic factors, including temperature, pressure, oxygen, water availability, and pollutants can readily disrupt the conformation and/or function of all types of proteins, e.g., enzymes, transporters, and structural proteins. The current review provides an update on recent advances in understanding the roles and responses of chaperones in aiding animals to deal with environmental stress, offering new information on chaperone action in supporting survival strategies including torpor, hibernation, anaerobiosis, estivation, and cold/freeze tolerance among both vertebrate and invertebrate species.

Effects of a maximal cycling all-out anaerobic test on visual performance.

CLINICAL RELEVANCE: All-out exercise may not impair all central nervous system processes, such as those related to visual-motor abilities, and may actually prove stimulatory to such tasks allowing athletes and sports conditioning specialists to develop strategies to take advantage of/mitigate the effects of such exercise on athletic performance. BACKGROUND: Despite research indicating that visual-motor abilities play a critical role in athletic performance, research has primarily focused on the effect of all-out exercise on processes along the motor pathway, such as resultant force production or simple cognitive tasks. Such research has neglected to investigate the effect of all-out exercise on visual tasks. When investigations on visual tasks are forthcoming, they focus on prolonged aerobic exercise, which is not the primary metabolic pathway for all, or even the majority of sports. METHODS: Sixty untrained males (experimental group; N = 30, control group; N = 30) completed a standardised six-item baseline sports vision test battery and one week later, the experimental participants returned to undertake a 30-second Wingate anaerobic test (30-WAnT) immediately followed by the same test battery. RESULTS: Significant (P < 0.05) improvements were found in accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness and hand-eye coordination (P < 0.001 for all), but not visual memory (P = 0.242) following the 30-WAnT. CONCLUSIONS: Although the mechanisms underlying these improvements in visual task performance have not yet been studied, this study suggests that simple anaerobic all-out exercise does not cause central- or brain-based fatigue impairing the oculomotor system but may rather provide "excitability" of the underlying motor cortex, motoneurons and/or corticofugal connections utilised in visual task response. It appears that the sweeping improvements in visual task performance elucidate the need for an intense anaerobic warm-up when training visual skills and when visual skills form an integral part of athletic performance.

Role of Pv-aCO2 gradient and Pv-aCO2/Ca-vO2 ratio during cardiac surgery: a retrospective observational study

Abstract Introduction: Arterial lactate, mixed venous O2 saturation, venous minus arterial CO2 partial pressure (Pv-aCO2) and the ratio between this gradient and the arterial minus venous oxygen content (Pv-aCO2/Ca-vO2) were proposed as markers of tissue hypoperfusion and oxygenation. The main goals were to characterize the determinants of Pv-aCO2 and Pv-aCO2/Ca-vO2, and the interchangeability of the variables calculated from mixed and central venous samples. Methods: 35 cardiac surgery patients were included. Variables were measured or calculated: after anesthesia induction (T1), end of surgery (T2), and at 6-8 hours intervals after ICU admission (T3 and T4). Results: Macrohemodynamics was characterized by increased cardiac index and low systemic vascular resistances after surgery (p < 0.05). Hemoglobin, arterial-pH, lactate, and systemic O2 metabolism showed significant changes during the study (p < 0.05). Pv-aCO2 remained high and without changes, Pv-aCO2/Ca-vO2 was also high and decreased at T4 (p < 0.05). A significant correlation was observed globally and at each time interval, between Pv-aCO2 or Pv-aCO2/Ca-vO2 with factors that may affect the CO2 hemoglobin dissociation. A multilevel linear regression model with Pv-aCO2 and Pv-aCO2/Ca-vO2 as outcome variables showed a significant association for Pv-aCO2 with SvO2, and BE (p < 0.05), while Pv-aCO2/Ca-vO2 was significantly associated with Hb, SvO2, and BE (p < 0.05) but not with cardiac output. Measurements and calculations from mixed and central venous blood were not interchangeable. Conclusions: Pv-aCO2 and Pv-aCO2/Ca-vO2 could be influenced by different factors that affect the CO2 dissociation curve, these variables should be considered with caution in cardiac surgery patients. Finally, central venous and mixed values were not interchangeable.

Ventilatory Muscle Strength Six Months After Coronary Artery Bypass Grafting in Patients Submitted to Inspiratory Muscular Training Based on Anaerobioc Threshold: A Clinical Trial

Abstract Introduction Coronary artery bypass grafting (CABG) surgery is associated with a decline in ventilatory muscle strength and lung function. Inspiratory muscle training (IMT) based on anaerobic threshold (AT) has been used to minimize the impact of CABG on these parameters, but the long-term impact is unknown. Objective To test the hypothesis that AT-based IMT improves inspiratory muscle strength and lung function even six months after CABG. Methods This is a randomized controlled clinical trial. In the preoperative period, maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), vital capacity (VC) and peak expiratory flow (PEF) rate were assessed. On the first postoperative day, patients were randomized into two groups: AT-based IMT (IMT-AT) (n=21) where the load was prescribed based on glycemic threshold and conventional IMT (IMT-C) (n=21), with load of 40% of MIP. Patients were trained during hospitalization until the day of discharge and were assessed at discharge and six months later. For within-group comparison, paired Student's t-test or Wilcoxon test was used, and independent Student's t-test or the Mann-Whitney test was used to analyze the different time points. A p<0.05 was considered significant. Results At six months after CABG surgery, statistical difference was found between the IMT-AT and the IMT-C groups in MIP (difference between the means of -5cmH2; 95% CI=- 8.21to-1.79) and VC (difference between the means of -2ml/kg;95%CI=-3.87to-0.13). No difference was found between groups in the other variables analyzed. Conclusion IMT-AT promoted greater recovery of inspiratory muscle strength and VC after six months of CABG when compared to conventional training.

Fitness training of athletes in freestyle skiing / Treinamento de aptidão física de atletas em esqui de estilo livre / Entrenamiento de aptitud física de atletas en esquí de estilo libre

ABSTRACT Introduction: Physical training is essential to physical fitness in freestyle skiers. The domain of stability in the technical movements is a determinant of the competition, always constantly improving. Objective: Develop a physical training program adapted to freestyle skiing. Methods: Twelve freestyle skiers were selected as volunteers for the experiment. This paper compares athletes' physical qualities and individual abilities before and after physical training. Through recent research, the athletes' physical condition was comprehensively evaluated to test the effectiveness of their physical training. results: Freestyle skiers showed good anaerobic fitness. A relationship was found between the maximum number of thrusts, the degree of spin in the air, the maximum power duration, and the power decay rate (P<0.05). In the body balance test, the lower limbs showed deficiencies in anteroposterior mobility, while bipodal balance showed no significantly statistical differences (P>0.05). Conclusion: This paper systematically studies body composition, the center of gravity strength, anaerobic capacity, and balance in freestyle skiers. The results provide a good assessment of the effect of fitness training on freestyle ski athletes. These results have particular guiding significance for formulating and implementing training programs focused on the sport. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: O treinamento físico é parte essencial da aptidão física em esquiadores de estilo livre. O domínio da estabilidade nos movimentos técnicos é determinante sobre as competições, estando sempre em constante aprimoramento. Objetivo: Elaborar um programa de treinamento físico adaptado ao esporte do esqui de estilo livre. Métodos: Selecionou-se 12 esquiadores de estilo livre como voluntários ao experimento. Este artigo compara as qualidades físicas e habilidades individuais dos atletas antes e depois do treinamento físico. Através de pesquisas recentes, avaliou-se de forma abrangente a condição física dos atletas para testar a eficácia de seu treinamento físico. Resultados: Os esquiadores de estilo livre apresentaram uma boa praticabilidade anaeróbica. Foi encontrada uma relação particular entre o número máximo de propulsões e o grau de giro no ar, a duração máxima da potência e a taxa de decaimento da potência (P<0,05). No teste de equilíbrio corporal, os membros inferiores apresentaram deficiências de mobilidade anteroposterior, enquanto o equilíbrio bipodal não apresentou diferenças significativamente estatísticas (P>0,05). Conclusão: Este artigo fornece um estudo sistemático da composição corporal, força do centro gravitacional, capacidade anaeróbica e equilíbrio em esquiadores de estilo livre. Os resultados proporcionam uma boa avaliação do efeito de treinamento de aptidão física nos atletas de esqui de estilo livre. Estes resultados têm um significado orientador particular para a formulação e implementação de programas de treinamento focados na modalidade. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: El entrenamiento físico es una parte esencial de la aptitud física en los esquiadores de estilo libre. El dominio de la estabilidad en los movimientos técnicos es determinante sobre las competiciones, estando siempre en constante mejora. Objetivo: Desarrollar un programa de entrenamiento físico adaptado al deporte del esquí de estilo libre. Métodos: Se seleccionaron doce esquiadores de estilo libre como voluntarios para el experimento. Este artículo compara las cualidades físicas y las capacidades individuales de los atletas antes y después del entrenamiento físico. Mediante una investigación reciente, se evaluó exhaustivamente la condición física de los atletas para comprobar la eficacia de su entrenamiento físico. Resultados: Los esquiadores de estilo libre mostraron una buena aptitud anaeróbica. Se encontró una relación particular entre el número máximo de empujes y el grado de giro en el aire, la duración de la potencia máxima y la tasa de disminución de la potencia (P<0,05). En la prueba de equilibrio corporal, los miembros inferiores mostraron deficiencias en la movilidad anteroposterior, mientras que el equilibrio bipodal no mostró diferencias estadísticas significativas (P>0,05). Conclusión: Este artículo proporciona un estudio sistemático de la composición corporal, la fuerza gravitatoria central, la capacidad anaeróbica y el equilibrio en esquiadores de estilo libre. Los resultados proporcionan una buena evaluación del efecto del entrenamiento físico en los atletas de esquí de estilo libre. Estos resultados tienen una especial importancia orientativa para la formulación y aplicación de programas de entrenamiento centrados en este deporte. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.