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The hemodynamic behavior of the elderly patient can be compromised during the intraoperative period by decreasing cardiac output, both in response to the physiological wear and tear of age, and because of anesthetic agents. The objective of the pre- sent study was to identify the usefulness of dobutamine to increase cardiac output and sustain systemic oxygenation during the perioperative period in the elderly surgical patient. MATERIAL AND METHOD: A descriptive study ­ Case Series ­ was carried out in surgical elderly patients, during the perioperative phase, to whom dobutamine was administered to 2 gammas. The variables of cardiac output and systemic oxygenation were analyzed in four phases, using repeated measures ANOVA and/or Friedman Analy- sis (p < 0.05). And in two phases using Paired T and/or Wilcoxon Marked Ranges (p < 0.05). RESULTS: A total of 18 patients were studied, who met the exclusion criteria, considered as ASA III, with an age of X = 81.9 years ± SD 8.23. An increase in cardiac output and oxygen availability was observed, in supra-optimal values, with statistically significant differences (p = 0.001; and p = 0.001 respectively). Systemic Vascular Resistances had a decreasing behavior during the intraoperative phase, with statistically significant differences (p = 0.001). The heart rate remained constant, despite presenting statistically significant differences (p = 0.027). CONCLUSIONS: The administration of dobutamine at a rate of 2 gammas is useful in favoring cardiac output and systemic oxygenation throughout the perioperative period in elderly patients.

El comportamiento hemodinámico del paciente anciano se puede comprometer durante el transoperatorio al disminuir el gasto cardiaco, tanto como respuesta al desgaste fisiológico de la edad, como por el efecto de los agentes anestésicos. El objetivo del presente estudio, fue identificar la utilidad de la dobutamina para incrementar el gasto cardiaco y sostener la oxigenación sistémica durante el perioperatorio, en el paciente anciano quirúrgico. MATERIAL Y MÉTODO: Se realizó un estudio descriptivo -Serie de Casos-, en pacientes ancianos quirúrgicos, durante la fase del perioperatorio, a los cuales se les administró dobutamina a 2 gammas. Se analizaron las variables del gasto cardiaco y la oxigenación sistémica en cuatro fases, mediante ANOVA de medidas repetidas y/o análisis de Friedman (p < 0,05). Y en dos fases mediante T Pareada y/o Rangos Señalados de Wilcoxon (p < 0,05).RESULTADOS: Se estudiaron un total de 18 pacientes, que cubrieron los criterios de exclusión, considerados como ASA III, con una edad de X = 81,9 años ± DE 8.23. Se observó un incremento en el gasto cardiaco y en la disponibilidad de oxígeno, en valores supraóptimos, con diferencias estadísticamente significativas (p = 0,001; y p = 0,001 respectivamente). Las Resistencias Vasculares Sistémicas tuvieron un comportamiento de descenso durante la fase del transoperatorio, con diferencias estadísticamente significativas (p = 0,001). La frecuencia cardiaca se mantuvo constante, a pesar de presentar diferencias estadísticamente significativas (p = 0,027). CONCLUSIONES: La administración de dobutamina a razón de 2 gammas reporta utilidad al favorecer el gasto cardiaco y la oxigenación sistémica, durante todo el perioperatorio en el paciente anciano.

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Forced aeration is one of the major energy consumption factors of the bioleaching process of run-of-mine ore. The effect of aeration in the microbial community has scarcely been studied at industrial level. Leptospirillum ferriphilum is one of the most representative species of the Fe3+ producing population in this kind of systems. We analyzed the effect of oxygen availability on L. ferriphilum by growth activity and transcriptional dynamics of its two terminal oxidases (cbb3 and bd complexes) under different experimental test: culture reactor, bioleaching column, and industrial heap tests. Relatively low O2 availability triggered important changes in the microbial community composition, cell growth, microbial activity and cydAB genes transcription in all cases of study. We assessed the potential role of the terminal oxidases on the adaptation to variable aeration conditions in different lifestyles of L. ferriphilum and identified transcriptional markers associated to oxygen metabolism in an industrial system. An interesting hypothesis about the possible role of the cbb3 complex in the response to oxidative stress as well as their role as a high oxygen-affinity oxidase in L. ferriphilum is proposed and discussed. This study successfully proves the function of the cydAB genes as valid genetic markers for low-grade copper industrial bioleaching systems.

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Reactive oxygen species and nitrogen species (ROS and RNS), produced in a wide range of physiological process even under low oxygen availability, are among the main stressors found in the environment. Strategies developed to combat them constitute key features in bacterial adaptability and survival. Pseudomonas extremaustralis is a metabolic versatile and stress resistant Antarctic bacterium, able to grow under different oxygen conditions. The present work explores the effect of oxidative stress under low oxygen conditions in P. extremaustralis, by combining RNA deep sequencing analysis and physiological studies. Cells grown under microaerobiosis exhibited more oxidative damage in macromolecules and lower survival rates than under aerobiosis. RNA-seq analysis showed an up-regulation of genes related with oxidative stress response, flagella, chemotaxis and biofilm formation while chaperones and cytochromes were down-regulated. Microaerobic cultures exposed to H2O2 also displayed a hyper-flagellated phenotype coupled with a high motility behavior. Moreover, cells that were subjected to oxidative stress presented increased biofilm formation. Altogether, our results suggest that a higher motile behavior and augmented capacity to form biofilm structures could work in addition to well-known antioxidant enzymes and non-enzymatic ROS scavenging mechanisms to cope with oxidative stress at low oxygen tensions.

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BACKGROUND: Azotobacter vinelandii is a bacterium that produces alginate and polyhydroxybutyrate (P3HB); however, the role of NAD(P)H/NAD(P)+ ratios on the metabolic fluxes through biosynthesis pathways of these biopolymers remains unknown. The aim of this study was to evaluate the NAD(P)H/NAD(P) + ratios and the metabolic fluxes involved in alginate and P3HB biosynthesis, under oxygen-limiting and non-limiting oxygen conditions. RESULTS: The results reveal that changes in the oxygen availability have an important effect on the metabolic fluxes and intracellular NADPH/NADP+ ratio, showing that at the lowest OTR (2.4 mmol L-1 h-1), the flux through the tricarboxylic acid (TCA) cycle decreased 27.6-fold, but the flux through the P3HB biosynthesis increased 6.6-fold in contrast to the cultures without oxygen limitation (OTR = 14.6 mmol L-1 h-1). This was consistent with the increase in the level of transcription of phbB and the P3HB biosynthesis. In addition, under conditions without oxygen limitation, there was an increase in the carbon uptake rate (twofold), as well as in the flux through the pentose phosphate (PP) pathway (4.8-fold), compared to the condition of 2.4 mmol L-1 h-1. At the highest OTR condition, a decrease in the NADPH/NADP+ ratio of threefold was observed, probably as a response to the high respiration rate induced by the respiratory protection of the nitrogenase under diazotrophic conditions, correlating with a high expression of the uncoupled respiratory chain genes (ndhII and cydA) and induction of the expression of the genes encoding the nitrogenase complex (nifH). CONCLUSIONS: We have demonstrated that changes in oxygen availability affect the internal redox state of the cell and carbon metabolic fluxes. This also has a strong impact on the TCA cycle and PP pathway as well as on alginate and P3HB biosynthetic fluxes.

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AIM: To evaluate the influence of aeration on persister levels from Acinetobacter calcoaceticus-baumannii isolates exposed to meropenem or tobramycin, as well as analyze morphological and structural changes in persisters. MATERIALS & METHODS: Levels of persisters were determined after a 48-h exposure to tobramycin or meropenem under aerated or static conditions, and persisters were analyzed by scanning and transmission electron microscopy. RESULTS: The fractions of persisters varied between isolates. Aeration reduced cell survival under each antibiotic treatment, and cell survival decreased as the tobramycin concentration was increased. Interestingly, division septa were observed in persisters by electron microscopy. CONCLUSION: Aeration may have stimulated bacterial growth, providing more targets for antibiotic action and leading to increased production of reactive oxygen species, which decreased levels of persisters.

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BACKGROUND: Understanding the effects of oxygen levels on yeast xylose metabolism would benefit ethanol production. In this work, xylose fermentative capacity of Scheffersomyces stipitis, Spathaspora passalidarum, Spathaspora arborariae and Candida tenuis was systematically compared under aerobic, oxygen-limited and anaerobic conditions. RESULTS: Fermentative performances of the four yeasts were greatly influenced by oxygen availability. S. stipitis and S. passalidarum showed the highest ethanol yields (above 0.44 g g-1) under oxygen limitation. However, S. passalidarum produced 1.5 times more ethanol than S. stipitis under anaerobiosis. While C. tenuis showed the lowest xylose consumption rate and incapacity to produce ethanol, S. arborariae showed an intermediate fermentative performance among the yeasts. NAD(P)H xylose reductase (XR) activity in crude cell extracts correlated with xylose consumption rates and ethanol production. CONCLUSIONS: Overall, the present work demonstrates that the availability of oxygen influences the production of ethanol by yeasts and indicates that the NADH-dependent XR activity is a limiting step on the xylose metabolism. S. stipitis and S. passalidarum have the greatest potential for ethanol production from xylose. Both yeasts showed similar ethanol yields near theoretical under oxygen-limited condition. Besides that, S. passalidarum showed the best xylose consumption and ethanol production under anaerobiosis.

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Abstract Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30 °C, 200 rpm, for 48 h in 125 mL Erlenmeyer flasks containing either 25 or 50 mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67 g g-1) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34 g L-1 h-1) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate.

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Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30 °C, 200 rpm, for 48 h in 125 mL Erlenmeyer flasks containing either 25 or 50 mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67 g g-1) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34 g L-1 h-1) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate.(AU)

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Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30°C, 200rpm, for 48h in 125mL Erlenmeyer flasks containing either 25 or 50mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67gg(-1)) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34gL(-1)h(-1)) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate.

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The physiology of B. subtilis R14 was investigated in minimal medium under excess-oxygen and oxygen-limited conditions. Growth and efficient sporulation could be achieved in excess-oxygen culture on medium with readily metabolizable carbon and nitrogen sources, which allowed high growth rate and high biomass yield. A short transition phase between the exponential growth and sporulation could be attained by formulating a medium with a well-balanced C/N ratio. Under oxygen-limitation, but in the presence of essential nutrients (i.e. excess-nutrient cultivation), B. subtilis R14 produced bioactive compounds, which showed activity against several phytopathogenic bacteria. Under anaerobic condition, the organism did not grow neither through fermentation nor anaerobic respiration. However, addition of pyruvate to the medium allowed its growth through fermentation and anaerobic respiration. The knowledge acquired in this work could be relevant both for the design of a production process as well as for the formulation of an effective commercial biocontrol product.

A fisiologia de B. subtilis R14 foi investigada em meio mínimo em condições de excesso e limitação de oxigênio. Crescimento e esporulação eficientes foram obtidas em culturas com excesso de oxigênio em meio contendo fontes de carbono e nitrogênio de fácil assimilação, que permitiram alta taxa de crescimento e alto rendimento em biomassa. Uma fase de transição curta, entre o crescimento exponencial e a esporulação, pode ser obtida pela formulação de um meio com razão C/N balanceada. Sob limitação de oxigênio, mas em presença de nutrientes essenciais, B. subtilis R14 produziu compostos bioativos. Os compostos apresentaram atividade contra várias bactérias fitopatogênicas. Sob condição de anaerobiose, o microrganismo não cresceu, nem através de fermentação nem de respiração anaeróbica. A adição de piruvato ao meio permitiu o crescimento, tanto através de fermentação como de respiração anaeróbica. O conhecimento adquirido neste trabalho é relevante tanto para o projeto do processo de produção quanto para a formulação de um produto comercial eficiente para biocontrole.

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Growth and polymer synthesis were studied in a recombinant E. coli strain carrying phaBAC and phaP of Azotobacter sp. strain FA8 using different carbon sources and oxygen availability conditions. The results obtained with glucose or glycerol were completely different, demonstrating that the metabolic routes leading to the synthesis of the polymer when using glycerol do not respond to environmental conditions such as oxygen availability in the same way as they do when other substrates, such as glucose, are used. When cells were grown in a bioreactor using glucose the amount of polymer accumulated at low aeration was reduced by half when compared to high aeration, while glycerol cultures produced at low aeration almost twice the amount of polymer synthesized at the higher aeration condition. The synthesis of other metabolic products, such as ethanol, lactate, formate and acetate, were also affected by both the carbon source used and aeration conditions. In glucose cultures, lactate and formate production increased in low agitation compared to high agitation, while poly(3-hydroxybutyrate) synthesis decreased. In glycerol cultures, the amount of acids produced also increased when agitation was lowered, but carbon flow was mostly redirected towards ethanol and poly(3-hydroxybutyrate). These results indicated that carbon partitioning differed depending on both carbon source and oxygen availability, and that aeration conditions had different effects on the synthesis of the polymer and other metabolic products when glucose or glycerol were used.

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