Evaluación de medidas para reducir la transmisión de COVID-19 en espacios cerrados, Tegucigalpa, Honduras / Evaluation of measures to reduce COVID-19 transmission in closed spaces, Tegucigalpa, Honduras

Antecedentes. Ante la evidencia que establece una transmisión aérea del SARS-CoV-2, es primordial buscar nuevas formas para reducir la transmisión. El monitoreo a través de medidores de dióxido de carbono (CO 2 ) permite determinar la calidad de aire en espacios cerrados. Objetivo: Evaluar niveles de CO 2 y uso de medidas de seguridad para reducir la transmisión de COVID-19 en aulas universitarias, Tegucigalpa, Honduras, abril-mayo 2022. Métodos: Estudio observacional descriptivo transversal sobre aulas y estudiantes universitarios. Los datos se obtuvieron por observación, medición y documentación. La muestra fue a conveniencia. Se midieron las concentraciones de CO2 en 5 aulas usando un medidor infrarrojo marca ARANET4. Se registraron las medidas de bioseguridad utilizadas. Se realizó análisis univariado por medio de frecuencia y medidas de tendencia central; se calculó coeficientes de correlación de Pearson y valores de p. Se obtuvo consentimiento informado de los participantes. Resultados: De los 86 participantes, 91.9% (79) aplicaba medidas de bioseguridad. Los niveles máximos de CO 2 encontrados en 5 aulas se encontraron en el nivel recomendado para espacios de clases (clasificación Calidad del Aire Interior IDA, Subdirección de Salud Pública, Madrid, España). Discusión: Los niveles de CO 2 en las aulas se elevaron con la presencia de estudiantes. Sin embargo, los niveles alcanzados no sugieren un riesgo. Honduras no cuenta con normas de calidad del aire para la protección a la salud de los impactos de los contaminantes atmosféricos. Es necesario realizar estudios con mayor tamaño muestral en cuanto a sitios y participantes...(AU)

Comparative analysis on occupational hazards of three welding operations / 中华劳动卫生职业病杂志

Objective: To explore the occupational hazards caused by three kinds of welding operations, and to provide data support for individual protection. Methods: In October 2020, the welding fumes, metal elements and welding arc generated by three welding operations of argon gas shielded welding (JS80 welding wire) , manual welding (ZS60A welding rod) and carbon dioxide shielded welding (907A flux cored wire) were collected and measured in the welding laboratory. The samples were analyze and compare in the laboratory, and the differences of the occupational hazard factors of the three welding operations were judged. Results: The concentration of welding fume produced by carbon dioxide shielded welding, manual welding (ZS60A electrode) , and argon gas shielded welding (JS80 welding wires) were 6.80 mg/m(3), 6.17 mg/m(3), and 3.13 mg/m(3), respectively. The effective irradiance of the welding arc outside the welding mask from high to low is manual welding (ZS60A electrode) , carbon dioxide shielded welding (907A flux-cored welding wire) , and argon shielded welding (JS80 welding wire) , respectively 1 010.7, 740.9, 589.5 μW/cm(2). The long-wave ultraviolet UVA intensity generated by argon shielded welding (JS80 welding wire) is the largest, which is 1 500 μW/cm(2). The content of Mn in the three welding operations is the highest, and JS80 welding wire has the highest Mn content of 128493.2 mg/kg. 907A flux cored wire has the highest Ti content, which is 24355.5mg/kg. The electrode ZS60A has the highest Cu content, which is 24422.12 mg/kg. Conclusion: The intensity of occupational hazards is different in the three kinds of welding operations, so the methods of personal protective equipment, field exposure assessment and health monitoring should be more targeted.

Strategies for Collection and Analysis of Samples in Simple Asphyxiant Gas Acute Poisoning Death Cases / 法医学杂志

At present, the death cases of simple asphyxiant gas acute poisoning are increasing sharply. Common asphyxiant gases in death cases include nitrogen, helium, carbon dioxide, methane, propane, laughing gas, etc. Simple asphyxiant gas has no affinity for biological matrices and escapes quickly, which puts forward new requirements for autopsy procedures, selection and collection of samples, laboratory analysis and identification. This paper reviews the research and development process of death cases caused by simple asphyxiant gas acute poisoning and put forwards the collection and analysis strategy of the samples in such cases. The most valuable biological samples in such cases should be lung tissues associated with the airways, followed by brain tissue and cardiac blood. Gaseous samples from the esophageal cavity, tracheal cavity, pulmonary bronchi, gastric and cardiac areas are also recommended as valuable samples. In the case of postmortem examination, the gas should be injected into gas sample bag directly. Biological materials such as tissue and blood should be directly sealed in head-space vials and analyzed by using the headspace gas chromatography-mass spectrometry.

Kinetic characterization and modeling of a microalgae consortium isolated from landfill leachate under a high CO2 concentration in a bubble column photobioreactor

BACKGROUND: The determination of kinetic parameters and the development of mathematical models are of great interest to predict the growth of microalgae, the consumption of substrate and the design of photobioreactors focused on CO2 capture. However, most of the models in the literature have been developed for CO2 concentrations below 10%. RESULTS: A nonaxenic microalgal consortium was isolated from landfill leachate in order to study its kinetic behavior using a dynamic model. The model considered the CO2 mass transfer from the gas phase to the liquid phase and the effect of light intensity, assimilated nitrogen concentration, ammonium concentration and nitrate concentration. The proposed mathematical model was adjusted with 13 kinetic parameters and validated with a good fit obtained between experimental and simulated data. CONCLUSIONS: Good results were obtained, demonstrating the robustness of the proposed model. The assumption in the model of DIC inhibition in the ammonium and nitrate uptakes was correct, so this aspect should be considered when evaluating the kinetics with microalgae with high inlet CO2 concentrations.

Elevated CO2 concentration improves functional traits and early growth of the widespread species Enterolobium contortisiliquum (Vell. ) Morong / Elevada concentração de CO2 melhora as características funcionais e o crescimento inicial da espécie generalista Enterolobium contortisiliquum (Vell. ) Morong

Enterolobium contortisiliquum is a neotropical widespread species that occurs in native AtlanticForest, Cerrado and Caatinga vegetation in Brazil. Outside Brazil, it occurs in Argentina, Bolivia, Paraguay, and Uruguay. The objective of this study was to investigate the influence of high carbon dioxide concentration [CO2] on leaf gas exchange, chlorophyll content, chlorophyll a fluorescence, growth, and biomass allocation among roots, stems, and leaves in young plants of E. contortisiliquum. After germination, twenty days old individuals of E. contortisiliquum were grown in open-top chambers (OTC) at two different [CO2] (400 ppm and 700 ppm). Physiological measurements were made when the plants had been grown in OTC for 170, 200, 230, and 260 days. The higher [CO2] favored the early growth of E. contortisiliquum by increasing maximum net photosynthesis (PN) and water use efficiency. Under high [CO2], root dry mass increased in E. contortisiliquum, which might be a trait that will benefit this species by enhancing water uptake, particularly in seasonally dry environments.

Enterolobium contortisiliquum é uma espécie neotropical generalista, encontrada na vegetação nativa da Mata Atlântica do Brasil, no Cerrado e na Caatinga. Fora do país, também pode ser encontrada empaíses como Argentina, Bolívia, Paraguai e Uruguai. O objetivo deste estudo foi investigar a influência da alta concentração de dióxido de carbono [CO2] nas trocas gasosas foliares, no teor de clorofila, na fluorescência da clorofila a, no crescimento e alocação de biomassa entre raízes, caules e folhas em plantas jovens de E. contortisiliquum. Após a germinação, indivíduos de E. contortisiliquum de 20 dias de idade foram cultivados em câmaras de topo aberto (CTA), em duas diferentes [CO2] (400 ppm e 700 ppm). Asmedições fisiológicas foram realizadas no momento do cultivo das plantas em CTA por 170, 200, 230 e 260 dias. A alta [CO2] favoreceu o crescimento inicial de E. contortisiliquum aumentando a fotossíntese líquida máxima (PN) e a eficiência do uso da água. Sob alta [CO2], a massa seca da raiz aumentou em E. contortisiliquum, o que pode ser uma característica que beneficiará esta espécie, aumentando a absorção de água, particularmente em ambientes sazonalmente secos.

Effective Tidal Volume for Normocapnia in Very-Low-Birth-Weight Infants Using High-Frequency Oscillatory Ventilation

PURPOSE: Removal of CO₂ is much efficient during high-frequency oscillatory ventilation (HFOV) for preterm infants. However, an optimal carbon dioxide diffusion coefficient (DCO₂) and tidal volume (VT) have not yet been established due to much individual variance. This study aimed to analyze DCO₂ values, VT, and minute volume in very-low-birth-weight (VLBW) infants using HFOV and correlates with plasma CO₂ (pCO₂). MATERIALS AND METHODS: Daily respiratory mechanics and ventilator settings from twenty VLBW infants and their two hundred seventeen results of blood gas analysis were collected. Patients were treated with the Dräger Babylog VN500 ventilator (Drägerwerk Ag & Co.) in HFOV mode. The normocapnia was indicated as pCO₂ ranging from 45 mm Hg to 55 mm Hg. RESULTS: The measured VT was 1.7 mL/kg, minute volume was 0.7 mL/kg, and DCO₂ was 43.5 mL²/s. Mean results of the blood gas test were as follows: pH, 7.31; pCO₂, 52.6 mm Hg; and SpO₂, 90.5%. In normocapnic state, the mean VT was significantly higher than in hypercapnic state (2.1±0.5 mL/kg vs. 1.6±0.3 mL/kg), and the mean DCO₂ showed significant difference (68.4±32.7 mL²/s vs. 32.4±15.7 mL²/s). The DCO₂ was significantly correlated with the pCO₂ (p=0.024). In the receiver operating curve analysis, the estimated optimal cut-off point to predict the remaining normocapnic status was a VT of 1.75 mL/kg (sensitivity 73%, specificity 80%). CONCLUSION: In VLBW infants treated with HFOV, VT of 1.75 mL/kg is recommended for maintaining proper ventilation.

Changes in the microbial community during bioremediation of gasoline-contaminated soil

Abstract We aimed to verify the changes in the microbial community during bioremediation of gasoline-contaminated soil. Microbial inoculants were produced from successive additions of gasoline to municipal solid waste compost (MSWC) previously fertilized with nitrogen-phosphorous. To obtain Inoculant A, fertilized MSWC was amended with gasoline every 3 days during 18 days. Inoculant B received the same application, but at every 6 days. Inoculant C included MSWC fertilized with N–P, but no gasoline. The inoculants were applied to gasoline-contaminated soil at 10, 30, or 50 g/kg. Mineralization of gasoline hydrocarbons in soil was evaluated by respirometric analysis. The viability of the inoculants was evaluated after 103 days of storage under refrigeration or room temperature. The relative proportions of microbial groups in the inoculants and soil were evaluated by FAME. The dose of 50 g/kg of inoculants A and B led to the largest CO2 emission from soil. CO2 emissions in treatments with inoculant C were inversely proportional to the dose of inoculant. Heterotrophic bacterial counts were greater in soil treated with inoculants A and B. The application of inoculants decreased the proportion of actinobacteria and increased of Gram-negative bacteria. Decline in the density of heterotrophic bacteria in inoculants occurred after storage. This reduction was bigger in inoculants stored at room temperature. The application of stored inoculants in gasoline-contaminated soil resulted in a CO2 emission twice bigger than that observed in uninoculated soil. We concluded that MSWC is an effective material for the production of microbial inoculants for the bioremediation of gasoline-contaminated soil.

Hipertermia maligna: a propósito de un caso / Malignant hyperthermia: a case report

Malignant hyperthermia (MH) is a rare neuromuscular hereditary disorder, triggered in susceptible individuals by exposure to inhalational agents or succinylcholine and manifested as a hypermetabolic state. We report the case of a 22 years old male patient anesthetized with Desflurane in whom MH was suspected because of unexplained increased levels of End-Tidal carbon dioxide. Dantrolene was administered with good response. Respiratory acidosis and hyperkalemia were also detected but could be easily controlled. The postoperative period was uneventful with the exception of a superficial venous thrombosis at the dantrolene’s injection site. The patient was discharged eight days after the episode without sequela. Successful management of a malignant hyperthemia episode must include: early suspicion, asking for help and early treatment with dantrolene.

La Hipertermia Maligna es un trastorno neuromuscular hereditario infrecuente, manifestado por un estado hipermetabólico desencadenado en individuos susceptibles por la exposición a anestésicos halogenados o Succinilcolina. Se reporta el caso de un hombre de 22 años anestesiado con Desflurano, en quien el diagnóstico de Hipertermia Maligna se sospechó por la presencia de elevación inexplicada del CO2 espirado, que respondió a la suspensión del Desflurano y administración de Dantroleno. Se observó además hiperkalemia y acidosis respiratoria, que fueron fácilmente compensadas. La evolución postoperatoria fue satisfactoria, a excepción de una trombosis venosa superficial en el sitio de inyección del Dantroleno. El paciente fue dado de alta al 8avo día postoperatorio, sin secuelas. Las claves del manejo exitoso de un episodio de hipertermia maligna están en: Sospecha precoz, solicitar ayuda e inició rápido del tratamiento con Dantroleno.

Avaliação da qualidade do ar de um centro cirúrgico de um hospital do sul do Brazil / Evaluation of the quality of air in a surgical center of a hospital in the south of Brazil / Evaluación de la calidad del aire de un centro quirúrgico de un hospital del sur de Brasil

Objetivo Avaliar a qualidade do ar das salas do centro cirúrgico de um hospital no Sul do Brasil. Métodos Foi realizada uma avaliação dos parâmetros de confortabilidade (temperatura, luminosidade, concentração de dióxido de carbono e umidade relativa do ar), análise microbiológica e cromatográfica do material particulado presente nos filtros dos aparelhos de ar condicionados. Resultados Em relação aos aspectos de confortabilidade, três salas cirúrgicas não apresentaram temperatura de acordo com a legislação vigente, mas encontram-se dentro do padrão ideal nos demais fatores ambientais. Na análise do material particulado, obteve-se um maior número de bioaerossóis fúngicos de colônias viscosas do que as filamentosas. Conclusões Constatou-se que os principais aspectos da qualidade do ar no hospital são atendidos, no entanto há a necessidade de modificação de aspectos construtivos nas salas de cirurgia para que se reduza a possibilidade de contaminações por via atmosférica e possa reduzir a concentração de dióxido de carbono no ambiente.(AU)

Objective The aim of this study was to evaluate the quality of air in surgical centre rooms of a hospital in the South of Brazil. Methods An evaluation of the parameters of comfortability (temperature, luminosity, concentration of carbon dioxide and relative humidity), microbiological analysis and chromatographic of the particulate material present in the filters of air conditioners was carried out. Results Regarding the aspects of comfortability, three surgical rooms did not present temperature in accordance to the current legislation, but were found within the ideal patterns in other environmental factors. In the analysis of particulate material, a larger number of fungal bio-aerosols of viscous colonies was obtained than filamentous. Conclusion It was found that the main aspects related to the quality of air in the hospital being studied are being accomplished; however there is a need of modifying building aspects in the surgical rooms in order to reduce the possibility of contamination by air and decrease the concentration of carbon dioxide in the environment.(AU)

Objetivo Evaluar la calidad del aire de las salas del centro quirúrgico de un hospital en el "Vale do Rio Pardo", en el sur de Brasil. Métodos Fue realizada una evaluación de los parámetros de confortabilidad (temperatura, luminosidad, concentración de dióxido de carbono y humedad relativa del aire), análisis microbiológico y cromatográfico del material particulado presente en los filtros de los aparatos de aire acondicionados. Resultados En relación a los aspectos de confortabilidad, tres salas quirúrgicas no presentaron temperatura de acuerdo con la legislación vigente, pero se encuentran dentro del padrón ideal en los demás factores ambientales. En el análisis del material particulado, se obtuvo un número más grande de bioaerosoles fúngicos de colonias viscosas de que las filamentosas. Conclusión Se constató que los principales aspectos relacionados a la calidad del aire en el hospital en estudio, son atendidos, sin embargo, ahí la necesidad de cambio de aspectos constructivos en las salas de cirugía para que se reduzca la posibilidad de contaminaciones por vía atmosférica y pueda reducir la concentración de dióxido de carbono en el ambiente.(AU)

Variação temporal do efluxo de CO2do solo em sistemas agroflorestais com palma de óleo na Amazônia Oriental / Temporal variation of soil CO2 efflux in oil palm-based agroforestry systems in eastern Amazon

The soil carbon dioxide (CO2) efflux dynamics and its controlling factors of Amazonian agroforestry systems are poorly understood. The objective of this study was to evaluate the temporal variation of soil CO2 efflux in oil palm-based agroforestry systems and the relation between efflux and biotic (microbial and total soil carbon, microbial respiration, fine roots, individual components of agroforestry systems (AFS)) and abiotic factors (soil moisture and temperature). The measurements were taken during the less rainy (December 2010) and rainy (May 2011) periods. The soil CO2 efflux was highest during the rainy season, probably due to increased microbial activity influenced by climatic factors coupled with biotic factors. The soil CO2 efflux correlated positively with soil moisture and microbial biomass carbon and negatively with soil temperature and metabolic quotient, but these correlations were weak. The soil CO2 efflux was sensitive to the type of agroforestry system and to rainfall seasonality.

A dinâmica do efluxo de dióxido de carbono (CO2) do solo e seus fatores controladores em sistemas agroflorestais da Amazônia são pouco compreendidas. O objetivo deste estudo foi avaliar a variação temporal do efluxo de CO2 do solo em sistemas agroflorestais onde a palma de óleo é a cultura principal e sua relação com fatores bióticos (carbono microbiano do solo, carbono total do solo, respiração microbiana do solo, raízes finas do solo, indivíduos componentes dos sistemas agroflorestais (SAFs) ) e abióticos (umidade e temperatura do solo). As medições foram realizadas nos períodos menos chuvoso (dezembro de 2010) e chuvoso (maio de 2011). O efluxo de CO2 do solo foi mais alto no período chuvoso, provavelmente, devido à maior atividade microbiana nesse período influenciada por fatores climáticos aliados a fatores bióticos. O efluxo de CO2do solo se correlacionou positivamente com umidade do solo e carbono da biomassa microbiana e negativamente com temperatura do solo e quociente metabólico, porém as correlações foram fracas. O efluxo de CO2do solo foi sensível ao tipo de sistema agroflorestal e a sazonalidade da precipitação.

Comparison of independent and dependent culture methods for the detection of transient bacteremia in diabetic subjects with chronic periodontitis / Comparación entre métodos de cultivo independientes y dependientes para la detección de bacteriemia transitoria en individuos diabéticos con periodontitis crónica

Introduction: Oral-derived bacteremia may occur after several dental procedures and routine daily activities. Some conditions of the oral cavity may favor episodes of bacteremia. This would be the case of patients with diabetes mellitus and periodontitis, who exhibit exacerbated gingival inflammation and may be more prone to developing oral-derived bacteremia. Objective: To compare the effectiveness of an independent culture method (quantitative real-time PCR- qCR) and the most commonly used method (BacT-ALERT 3D ® ) for the diagnosis of bacteremia. Materials and methods: Blood samples were drawn from subjects with type 2 diabetes mellitus and chronic periodontitis before and after apple chewing. Samples were processed by an automated blood culture system (BacT-ALERT 3D ® ) monitored for 15 days with suitable subculture of positive cultures. In parallel, whole DNA from blood samples was purified using a commercial kit and screened by qPCR using a universal primer set of 16S rDNA for bacteria detection. Results: Blood cultures taken before apple chewing were shown to be negative by the two diagnostic methods. After chewing, two samples (11%) showed bacterial growth by BacT-ALERT 3D ® whereas qPCR did not detect the presence of bacteria in any sample. Conclusions: qPCR did not show greater effectiveness than the BacT-ALERT 3D ® in the detection of bacteremia of oral origin.

Introducción. Las bacteriemias de origen oral pueden ocurrir después de procedimientos odontológicos y de otros actos cotidianos. Algunas condiciones de la cavidad oral favorecen las bacteriemias como en el caso de pacientes con diabetes mellitus y periodontitis que presentan inflamación gingival exacerbada. Objetivo. Comparar la eficacia de un método independiente de cultivo (PCR cuantitativa) y otro dependiente (BacT-ALERT 3D ® ) en la detección de la bacteriemia. Materiales y métodos. Se tomaron muestras de sangre de individuos con diabetes mellitus de tipo II y periodontitis, antes y después de la masticación de manzana. Una alícuota se procesó por el sistema automatizado de hemocultivo (BacT-ALERT 3D ® ) y se monitorizó durante 15 días; la otra alícuota fue tratada para la extracción del ADN y procesada por RT-PCR usando un conjunto de cebadores de 16S rDNA exclusivos para bacterias. Resultados. En las muestras tomadas antes de masticar se confirmó la ausencia de bacterias mediante los dos métodos. En las muestras tomadas después de masticar la presencia de bacterias se evidenció únicamente en dos hemocultivos y en ninguna de las muestras se detectó la presencia de bacterias con el método de RT-PCR. Conclusiones. La PCR cuantitativa no mostró mayor eficacia que el BacT-ALERT 3D ® en la detección de la bacteriemia de origen oral.

Acute but not chronic metabolic acidosis potentiates the acetylcholine-induced reduction in blood pressure: an endothelium-dependent effect

Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control.

Effect of edible quinoa protein-chitosan based films on refrigerated strawberry (Fragaria × ananassa) quality

Background Strawberries are non-climacteric fruits with a low respiration rate, but are subject to serious fungal deterioration during postharvest handling. The edible coatings based on chitosan (CH), quinoa protein-chitosan (Q/CH) and quinoa protein-chitosan-sunflower oil (Q/CH/SO) may provide a solution to this problem. Thus, in this work CH, Q/CH and Q/CH/SO were elaborated and applied to fresh strawberries, and its effect on the strawberries shelf life during storage for 15 d was evaluated by mold and yeast count, fungal decay, carbon dioxide rate, physicochemical properties, and sensory evaluation. Results On all analysis days, the strawberries coated with the film-forming CH, Q/CH and Q/CH/SO solutions presented a significant lower amount of mold and yeast growth than the uncoated strawberries. Coated strawberries with Q/CH/SO decreased the CO2 emission rate by 60% compared to the uncoated strawberries. The color of the strawberries was not influenced by the films. There was no significant difference between the different coating groups and the uncoated group in the physicochemical parameters. Sensory analysis showed that the coating application retained the total sensorial quality. Conclusions Fresh strawberries coated with CH, Q/CH/SO and Q/CH edible films had longer shelf lives than uncoated fruits.

Diffusive emission of methane and carbon dioxide from two hydropower reservoirs in Brazil / Emissões difusivas de metano e de dióxido de carbono oriundas de dois reservatórios hidrelétricos

The role of greenhouse gas emissions from freshwater reservoirs and their contribution to increase greenhouse gas concentrations in the atmosphere is currently under discussion in many parts of the world. We studied CO2 and CH4 diffusive fluxes from two large neotropical hydropower reservoirs with different climate conditions. We used floating closed-chambers to estimate diffusive fluxes of these gaseous species. Sampling campaigns showed that the reservoirs studied were sources of greenhouse gases to the atmosphere. In the Serra da Mesa Reservoir, the CH4 emissions ranged from 0.530 to 396.96 mg.m–2.d–1 and CO2 emissions ranged from –1,738.33 to 11,166.61 mg.m–2.d–1 and in Três Marias Reservoir the CH4 fluxes ranged 0.720 to 2,578.03 mg.m–2.d–1 and CO2 emission ranged from -3,037.80 to 11,516.64 to mg.m–2.d–1. There were no statistically significant differences of CH4 fluxes between the reservoirs, but CO2 fluxes from the two reservoirs studied were significantly different. The CO2 emissions measured over the periods studied in Serra da Mesa showed some seasonality with distinctions between the wet and dry transition season. In Três Marias Reservoir the CO2 fluxes showed no seasonal variability. In both reservoirs, CH4 emissions showed a tendency to increase during the study periods but this was not statistically significant. These results contributed to increase knowledge about the magnitude of CO2 and CH4 emission in hydroelectric reservoirs, however due to natural variability of the data future sampling campaigns will be needed to better elucidate the seasonal influences on the fluxes of greenhouse gases.

Atualmente, em diversas partes do mundo, tem-se discutido muito sobre a contribuição das emissões de gases de efeito estufa oriundas de reservatórios hidrelétricos. Neste trabalho foram medidos fluxos difusivos de CO2 e CH4 em dois grandes reservatórios hidrelétricos neotropicais com diferentes condições climáticas (UHE Serra da Mesa e UHE Três Marias). Utilizamos câmaras flutuantes para estimar os fluxos difusivos de CO2 e CH4. As campanhas de amostragem mostraram que os dois reservatórios estudados apresentaram-se como fontes emissoras de gases por mecanismo de difusão. No reservatório de Serra da Mesa as emissões de CH4 variaram entre 0,530 e 396,96 mg.m–2.d–1 e as emissões de CO2 variaram entre –1.738,33 a 11.166,61 mg.m–2.d–1. No reservatório de Três Marias os fluxos de CH4 variaram entre 0,720 e 2.578,03 mg.m–2.d–1. Já os fluxos de CO2 variaram de -3.037,80 à 11.516,64 mg.m–2.d–1. Não houve diferença estatisticamente significativa dos fluxos de CH4 entre os reservatórios estudados, entretanto os fluxos de CO2 foram significativamente diferentes. As emissões de CO2 medidas ao longo dos períodos estudados em Serra da Mesa mostrou certa sazonalidade, com distinções entre o período de transição seco e úmido. No reservatório de Três Marias os fluxos de CO2 não apresentaram variabilidade sazonal. Em ambos os reservatórios, as emissões de CH4 apresentaram aumento do fluxo ao longo dos períodos de estudo, mas isso não foi estatisticamente significativo. Estes resultados contribuíram para aumentar o conhecimento sobre a variabilidade das emissões difusivas de CO2 e CH4 em reservatórios de usinas hidrelétricas. Entretanto, novas campanhas de amostragem serão necessárias para melhor estudar as influências sazonais sobre os fluxos dos gases de efeito estufa.

Productividad primaria en el Humedal Nacional Térraba-Sierpe, Costa Rica / Primary productivity in the National Térraba-Sierpe Wetland, Costa Rica

Resumen Se determinó la productividad primaria (PP) del fitoplancton en un amplio sector del Humedal Nacional Térraba Sierpe (HNTS) de Costa Rica, durante la estación lluviosa del año 2008 y en la estación seca del año 2009. Seis sitios se ubicaron en las áreas norte y central del humedal, donde por lo general ocurre la mayor influencia del aporte de caudal del Río Grande de Térraba. Se realizaron adicionalmente determinaciones de otros parámetros ambientales, asociados con la productividad primaria, como profundidad de penetración del disco de Secchi, la concentración de sólidos en suspensión, la concentración de clorofila a, la salinidad, la temperatura, la concentración del oxígeno disuelto en el agua, la concentración de nutrimentos inorgánicos disueltos (amonio, nitrito, fósforo disuelto, silicato), la conductividad eléctrica específica y se llevó a cabo un estudio basado en el análisis de componentes principales. La PP en el HNTS fue en general baja, con un valor máximo de 8.16gC/m2·d de PPN, el cual se registró en la estación seca, en marzo del 2009, en Isla Loros. Los sitios de mayor influencia del río (Samu y El Caite en la estación lluviosa), fueron los que tuvieron valores más bajos, mientras que los sitios con mayor influencia marina fueron los que presentaron los valores más altos de este estudio, cuyo promedio y desviación estándar fue de 0.79±0.50gC/m2.d (n=12), y la mediana fue 0.80gC/m2.d. Esta diferencia se debe principalmente al elevado aporte de agua dulce y de sólidos en suspensión del Río Grande de Térraba que limita el desarrollo del fitoplancton marino en el humedal. Es importante que se establezca y mantenga un programa de monitoreo de los parámetros medidos en este estudio, con al menos dos muestreos por año, uno en la época seca y otro en la época lluviosa, siguiendo el gradiente de salinidad desde el río hasta el mar al menos en dos direcciones.

Abstract Phytoplankton primary production (PP) was determined in a broad sector of the Térraba-Sierpe National Wetland, Costa Rica, from September to November 2008 in the rainy season and from January to March 2009 in the dry season. Six sampling stations were located at the Northern and Central zone of the wetland, according to the main expected flux of Río Grande de Térraba. Additionally other environmental parameters such as Secchi disk depth, suspended solid matter concentration, chlorophyll-a concentration, salinity, temperature, dissolved oxygen concentration, dissolved inorganic nutrients concentrations (phosphate, nitrate, ammonium and silicate), specific conductivity were also measured and a principal components analysis was performed. The PP in the Terraba-Sierpe National Wetland (HNTS by its Spanish name) was generally low, with a maximum value of 8.16gC/m2·d of Net Primary Productivity (NPP), which was recorded in the dry season, in March 2009, at Loros island. Sites that had a greater riverine influence showed lower PP values, while sites with greater marine influence presented higher PP values. These latter had an average and standard deviation of 0.79±0.50gC/m2·d (n=12). This difference is the result of the high input of freshwater and suspended solids from the Río Grande de Térraba which limits the development of marine phytoplankton in the wetland. Rev. Biol. Trop. 63 (Suppl. 1): 9-28. Epub 2015 April 01.

Quantification of ruminal microbiota and production of methane and carbonic dioxide from diets with inclusion of glycerin / Quantificação da microbiota ruminal e produção de metano e gás carbônico de dietas com inclusão de glicerina

The aim of this study was to quantify the liquid-associated bacteria and protozoa of the rumen and to evaluate the potential of in vitro production of gases CH4 and CO2 of diets with inclusion of glycerin for sheep. Two diets were formulated with a roughage:concentrate ratio of 20:80, according to the presence or absence of glycerin: G0 - control, without glycerin; and G10 - 10% glycerin as part of the concentrate. To quantify the liquid-associated bacteria and protozoa from the rumen and production of CH4 and CO2 gases, a completely randomized design was used. The diets had no effect (P>0.05) on production and composition of liquid-associated protozoa and bacteria from the rumen of lambs. Likewise, a (P>0.05) diet effect was not observed on production of CH4 and CO2 in vitro, which presented average concentrations of 24.55mL/g MS and 51.52mL/g MS, respectively. The use of 10% glycerin did not alter production or composition of ruminal microflora, and moreover, did not negatively impact the production of CH4 and CO2 gases in vitro.

Objetivou-se com este estudo quantificar as bactérias e protozoários líquido-associados do rúmen e avaliar o potencial de produção dos gases CH4 e CO2 in vitro de dietas com inclusão de glicerina para ovinos. Duas dietas foram formuladas, na proporção volumoso:concentrado de 20:80, conforme a presença ou ausência de glicerina: G0 - controle sem glicerina, G10 - 10% glicerina como parte do concentrado. Para a quantificação das bactérias e protozoários líquido-associados do rúmen e produção dos gases CH4 e CO2, utilizou-se o delineamento inteiramente ao acaso. Não foi observado efeito de dieta (P>0,05) sobre a produção e composição de protozoários e bactérias líquido-associados do rúmen de cordeiros. Da mesma forma, não houve efeito de dieta (P>0,05) sobre a produção de CH4 e CO2 in vitro, os quais apresentaram concentrações médias de 24,55mL/g MS e 51,52mL/g MS, respectivamente. O uso de 10% glicerina não altera a produção ou composição da microflora ruminal, e também não impacta negativamente a produção dos gases CH4 e CO2 in vitro.

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake / Amostragem diurna demonstra variação significativa na emissão de CO2 em um lago tropical produtivo

It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO2 because they receive allochthonous carbon inputs. However, autotrophy and CO2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO2 and CO2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO2 and CO2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO2 dynamics in tropical lakes. Net heterotrophy and CO2 outgassing from the lake were registered only at night, while significant CO2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO2 emissions from tropical lakes.

É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO2 e no fluxo de CO2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO2 quanto o fluxo de CO2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO2 por lagos tropicais.

Equilíbrio ácido-básico de embriões e pintos de corte em momentos críticos da incubação e submetidos a diferentes períodos de transferência para o nascedouro / Acid-base balance of embryos and broiler chicks in critical moments of incubation and submitted to different periods of transfer to the hatcher

Foram analisados os níveis de pCO2, pO2, pH e HCO3 - de embriões e pintos de corte provenientes de matrizes novas e velhas, nos momentos anteriores à bicagem interna e externa da casca e ao nascimento, submetidos a diferentes períodos de transferência para as condições ambientais dos nascedouros. Os tratamentos foram definidos pela idade da matriz (33 e 63 semanas) e pela transferência para o nascedouro (aos 15, 17 e 19 dias). O delineamento experimental foi em parcelas subdivididas, sendo a parcela os três momentos de transferência e a subparcela as duas idades das matrizes. Foram utilizadas seis repetições para cada tratamento, e o embrião ou o pinto foi considerado uma repetição. Os dados normais e homogêneos foram submetidos às análises de variância, e as médias comparadas pelos testes F, de Tukey e SNK. Embriões cujos ovos foram transferidos aos 15 dias para o nascedouro apresentaram melhor equilíbrio ácido-básico durante as fases pré-natal e perinatal. Durante o último terço da incubação, independentemente das diferentes condições ambientais às quais os embriões são submetidos e da idade da matriz, há capacidade de resposta fisiológica que permite uma estabilidade no equilíbrio ácido-básico dos pintos após a eclosão...

We analyzed the levels of pCO2, pO2, pH and HCO3 - in embryos and chicks from young and older breeders, in the moments before internal pipping, external pipping and at hatch and submitted to different periods in the environmental conditions of hatchers. The treatments were defined by breeder age (33 and 63 weeks) and transfer to the hatcher (at 15, 17 and 19 days). The experimental design was split plots with three periods in the hatcher and the plots were the two breeder ages. We used six replicates per treatment and the embryo or chick was considered a repetition. The normal data forms were submitted to analysis of variance and means were compared by F, Tukey and SNK tests. Embryos transferred at 15 days to the hatcher had better acid-base balance during the pre-and perinatal phases. During the last third of incubation, regardless of the different environmental conditions which the embryos are subjected and breeder age, there is physiological responsiveness that allows for stability in acid-base balance of the chicks after hatching...

Bicarbonato/CO2 aumenta dano em isquemia-reperfusão: da observação inicial à caracterização molecular / Bicarbonate/CO2 increase damage in ischemia-reperfusion injury: from observation to molecular characterization

Bicarbonato é uma importante espécie química para os seres vivos, sendo o principal tampão celular, alem de apresentar uma negligenciada atividade redox. Isquemia é um evento no qual existe inibição do aporte de nutrientes e oxigênio, sendo a reperfusão o retorno do fluxo de nutrientes e oxigênio, que é acompanhada por alta produção de radicais livres e morte celular. Nessa tese estudamos o efeito da presença de bicarbonato durante a isquemia-reperfusão. Em nosso modelo nós mantivemos o pH constante e modulamos a quantidade de bicarbonato enquanto células, órgãos e animais foram submetidos a isquemia-reperfusão. Utilizamos condições sem a presença de bicarbonato, a concentração basal sanguínea e uma concentração mais alta simulando o acúmulo de bicarbonato em condições isquêmicas. Nesses diversos modelos mostramos que a presença de bicarbonato aumenta o dano provocado por isquemia-reperfusão e provoca um aumento do acúmulo de proteínas oxidadas. A presença do bicarbonato não modifica a respiração, produção de espécies reativas de oxigênio, ou a morfologia mitocondrial, também não detectamos mudança na atividade do proteassoma e nos indicadores de autofagia geral. Entretanto detectamos um acúmulo de marcadores autofágicos na fração mitocondrial indicando inibição da mitofagia. Essa inibição foi confirmada ao detectarmos o acúmulo de uma proteína degradada especificamente por mitofagia enquanto não houve mudança em outra degradada pelo proteassoma. Além disso, ao inibirmos farmacologicamente a autofagia, reproduzimos o fenótipo causado pelo bicarbonato mesmo na sua ausência. Em conclusão, a presença de bicarbonato é deletéria em condições de isquemia/reperfusão devido a inibição da mitofagia

Bicarbonate is an important molecule in all living being, acting as the main cellular buffer. However, its biological and redox activity has been mostly neglected to date. Ischemia is an event in which an inhibition of nutrient availablity and oxygen flow occurs, while reperfusion is the return of nutrients and oxygen, accompanied of a burst of reactive oxygen species production and cell death. Here, we studied the effects of bicarbonate during cardiac ischemia-reperfusion. In our model, we kept the pH stable and changed the concentration of the bicarbonate. We then subjected cells, organs and animals to ischemia-reperfusion under conditions where there was no presence, basal blood concentration or a higher concentration of bicarbonate. In these diverse models, we found that the presence of bicarbonate increased damage after a ischemia-reperfusion, and promoted the accumulation of oxidized proteins. Bicarbonate did not change respiration, production of reactive oxygen species or the morphology of the mitochondria. There were also no changes in proteasome activity and in global autophagy markers, although there was an accumulation of mitophagy markers. We also found that mitophagy was responsible for the increased damage observed, since pharmacological inhibiting of autophagy abolished the increased damage caused by the presence of bicarbonate. In conclusion the presence of bicarbonate is deleterious in ischemia-reperfusion due mitophagy inhibition