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Extracranial cerebrovascular disease has been the subject of intense research throughout the world, and is of paramount importance for vascular surgeons. This guideline, written by the Brazilian Society of Angiology and Vascular Surgery (SBACV), supersedes the 2015 guideline. Non-atherosclerotic carotid artery diseases were not included in this document. The purpose of this guideline is to bring together the most robust evidence in this area in order to help specialists in the treatment decision-making process. The AGREE II methodology and the European Society of Cardiology system were used for recommendations and levels of evidence. The recommendations were graded from I to III, and levels of evidence were classified as A, B, or C. This guideline is divided into 11 chapters dealing with the various aspects of extracranial cerebrovascular disease: diagnosis, treatments and complications, based on up-to-date knowledge and the recommendations proposed by SBACV.
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CONTEXT: Community health workers (CHWs) are vital frontline public health workers. Given their trusted roles and connection to and understanding of the communities they serve, CHWs are able to link underserved communities to resources and public health agencies. With CHWs' increased prominence in the public health workforce, calls have been made for expanding and supporting CHW training and career development opportunities. PROGRAM: Public health training centers (PHTCs) are mandated to assess public health workforce needs, provide evidence-based professional development trainings, and increase students' aptitude for working with underserved and underresourced communities through applied practice experiences. Public health training centers can support CHWs in each of these areas. DESIGN: Case studies from 3 PHTCs are provided to exemplify how PHTCs are well positioned to support the critical CHW workforce via assessment, training, and student field placements. IMPLEMENTATION: A regional needs assessment survey with a designated section for CHWs, the provision of accessible and relevant CHW training, and CHW-focused student field placements were implemented in PHTC Regions 6/South Central, 1/New England, and 5/Great Lakes, respectively. EVALUATION: The Region 6 needs assessment found that CHWs in Oklahoma had multiple core roles and training interests. A crosswalk of needs and available training in the region guided the creation of tailored CHW trainings. Across 35 CHW-targeted trainings in Region 1, 88.5% of trainees were satisfied with the trainings and identified actions they could take to apply information they learned to their work. Significant improvements ( P < .001) in knowledge occurred across the 13 trainings that had pre-/posttests. In Region 5, students engaged with CHW-based organizations in Wisconsin to inform statewide CHW priority action items and deliverables and found the field placements meaningful for their academic experience. DISCUSSION: Public health training centers' strengths in workforce development can complement and extend existing efforts to support the CHW workforce.
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Agentes Comunitarios de Salud , Salud Pública , Agentes Comunitarios de Salud/educación , Humanos , Evaluación de Necesidades , Salud Pública/educación , Desarrollo de Personal , EstudiantesRESUMEN
Saccular superior vena cava aneurysms (SVCAs) are one of the rarest causes of mediastinal masses. Seventy years after the first published case report, to the best of our knowledge, fewer than 30 cases have been described in the literature. This article provides an overview of the peculiarities regarding diagnosis and treatment performed in these cases and addresses the protocol adopted in our case report. We present a saccular aneurysm resected through median sternotomy, under cardiopulmonary bypass and superior vena cava reconstruction using a bovine pericardial patch.
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Aneurisma/cirugía , Pericardio/trasplante , Procedimientos de Cirugía Plástica , Procedimientos Quirúrgicos Vasculares , Vena Cava Superior/cirugía , Adolescente , Adulto , Anciano , Aneurisma/diagnóstico por imagen , Animales , Puente Cardiopulmonar , Bovinos , Femenino , Xenoinjertos , Humanos , Masculino , Persona de Mediana Edad , Esternotomía , Resultado del Tratamiento , Vena Cava Superior/diagnóstico por imagen , Adulto JovenRESUMEN
Pollution due to waste generated by the oil industry has led to serious damage to ecosystems and the environment. Therefore, preventive and corrective actions must be taken to mitigate the ecological impact of waste resulting from oil-related activities, to explore and implement environment-friendly approaches, and achieve sustainable development. In this study, an alternative treatment for cuttings generated during the drilling of oil wells was investigated by extracting the hydrocarbons present in such cuttings through the use of carbon dioxide under supercritical conditions. The extractions were performed in a Supercritical Fluid Technologies Inc. Model SFT-150 extractor, under varying pressure (2300-6600 psi) and temperature (52-109 °C), while maintaining constant carbon dioxide flow rate and extraction time, to analyse the effect of these two thermodynamic variables on the extraction efficiency. During supercritical extraction, 21.51 g of total hydrocarbons from drill cuttings (oil/kg) were recovered at 6000 psi and 100 °C. The results indicated that pressure had the strongest effect on the extraction yield, with only a small amount of hydrocarbons recovered at the lowest pressure for all fractions. At <3000 psi pressure, increasing the temperature led to a decrease in the amount of recovered hydrocarbons; at >3000 psi pressure, increasing the temperature led to an increase in the extraction yield.
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Dióxido de Carbono , Ecosistema , Hidrocarburos , Yacimiento de Petróleo y Gas , TemperaturaRESUMEN
A population of Desertifilum (Cyanobacteria, Oscillatoriales) from an oligotrophic desertic biotope was isolated and characterized using a polyphasic approach including molecular, morphological, and ecological information. The population was initially assumed to be a new species based on ecological and biogeographic separation from other existing species, however, phylogenetic analyses based on sequences of the 16S rRNA gene and 16S-23S ITS region, placed this strain clearly within the type species, Desertifilum tharense. Comparative analysis of morphology, 16S rRNA gene similarity, 16S-23S ITS secondary structure, and percent dissimilarity of the ITS regions for all characterized strains supports placing the six Desertifilum strains (designated as PD2001/TDC17, UAM-C/S02, CHAB7200, NapGTcm17, IPPAS B-1220, and PMC 872.14) into D. tharense. The recognition of Desertifilum salkalinema and Desertifilum dzianense is not supported, although our analysis does support continued recognition of Desertifilum fontinale. Pragmatic criteria for recognition of closely related species are proposed based on this study and others, and more rigorous review of future taxonomic papers is recommended.
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Cianobacterias , ADN Bacteriano , Filogenia , ARN Ribosómico 16S , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: Duplex ultrasonography (DUS), although consolidated as the primary tool for the estimation of carotid stenosis, may be impaired by calcified plaques that promote acoustic shadow (AcS). AcS seems to hamper the quantification of the main parameter used in the determination of percentage stenosis, that is, the maximal peak systolic velocity (PSV) at the lesion site. The aim of our study was to compare the degrees of carotid artery stenosis in DUS/PSV and computed tomography angiography (CTA) in the presence of AcS. METHODS: During 36 months, 1,178 carotid DUS tests were performed. A total of 164 carotids in 139 patients showed AcS resulting from calcified plaques. Carotids with AcS were referred for a second imaging examination; thus, 62 carotids were analyzed by both DUS/PSV and CTA. CTA measured the area reduction at the lesion site to calculate the percent stenosis. PSV was measured immediately after the end of the AcS. According to velocities-based DUS criteria, stenoses were classified as mild (PSV < 125 cm/s), moderate (125 ≤ PSV ≤ 230 cm/s), and severe (PSV > 230). CTA and DUS/PSV measurements were compared to determine the accuracy of PSV in characterizing the severity of carotid stenosis with AcS. RESULTS: Of the 62 lesions, PSV characterized 10 as severe, 21 as moderate, and 31 as mild. According to the CTA study, there were 36 severe, 8 moderate, and 18 mild lesions. PSV underestimated in 27.79% the incidence of cases of severe carotid artery stenosis detected by the CTA. In addition, PSV overestimated the incidence of the cases of moderate and mild stenosis in 61.91% and 37.78%, respectively. The agreement ratio between the imaging examinations used in this study was 50%. DUS/PSV discretely correlated with CTA (r = 0.668, P < 0.0001, 95% confidence interval = 0.502-0.786). Using PSVs >125 and >230 as predictors of carotid lesions higher than 50% and 70%, respectively, the sensitivities were 63.3% and 27.8%, the specificities were 100%, the positive predictive values were 100%, and the negative predictive values were 71.9% and 50%. CONCLUSION: PSV alone is inadequate to quantify carotid stenosis in the presence of calcified plaques and AcS. Another image tool, such as CTA, could be recommendable for clinical decision-making.
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Arterias Carótidas/diagnóstico por imagen , Estenosis Carotídea/diagnóstico por imagen , Angiografía por Tomografía Computarizada , Placa Aterosclerótica , Ultrasonografía Doppler Dúplex , Calcificación Vascular/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Velocidad del Flujo Sanguíneo , Arterias Carótidas/patología , Arterias Carótidas/fisiopatología , Estenosis Carotídea/patología , Estenosis Carotídea/fisiopatología , Estenosis Carotídea/terapia , Toma de Decisiones Clínicas , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Flujo Sanguíneo Regional , Reproducibilidad de los Resultados , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Calcificación Vascular/patología , Calcificación Vascular/fisiopatología , Calcificación Vascular/terapiaRESUMEN
Pseudomonas citronellolis UAM-Ps1 co-metabolically transforms methyl tert-butyl ether (MTBE) to tert-butyl alcohol with n-pentane (2.6 mM), n-octane (1.5 mM) or dicyclopropylketone (DCPK) (4.4 mM), a gratuitous inducer of alkane hydroxylase (AlkB) activity. The reverse transcription quantitative real-time PCR was used to quantify the alkane monooxygenase (alkB) gene expression. The alkB gene was expressed in the presence of n-alkanes and DCPK and MTBE oxidation occurred only in cultures when alkB was transcribed. A correlation between the number of alkB transcripts and MTBE consumption was found (ΜΤΒΕ consumption in µmol = 1.44e(-13) x DNA copies, R(2) = 0.99) when MTBE (0.84 mM) was added. Furthermore, alkB was cloned and expressed into Escherichia coli and the recombinant AlkB had a molecular weight of 42 kDa. This is the first report where the expression of alkB is related to the co-metabolic oxidation of MTBE.
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Éteres Metílicos/metabolismo , Oxigenasas de Función Mixta/metabolismo , Pseudomonas/metabolismo , Alcohol terc-Butílico/metabolismo , Clonación Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Perfilación de la Expresión Génica , Oxigenasas de Función Mixta/genética , Peso Molecular , Oxidación-Reducción , Pseudomonas/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificaciónRESUMEN
Biodegradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with gaseous hexane (n-hexane > 95%) was investigated using Pseudomonas aeruginosa utilizing short chain aliphatic hydrocarbon (C(5)-C(8)). Kinetic batch experiments showed that MTBE was degraded even when hexane was completely exhausted with a cometabolic coefficient of 1.06 ± 0.16 mg MTBE mg hexane(-1). Intermediate tert-butyl alcohol (TBA) accumulation was observed followed by its gradual consumption. A maximum MTBE elimination capacity (EC(MAX)) of 35 g m(-3) h(-1) and removal efficiency (RE) of 70% were attained in mineral medium amended biofilters having an empty bed residence time (EBRT) of 1 min. For these experimental conditions, a maximum hexane EC of approximately 60 g m(-3) h(-1) was obtained at a load of 75 g m(-3) h(-1). Experiments under transient conditions revealed a competitive substrate interaction between MTBE and hexane. Biomass densities between 5.8 and 12.6 g L(biofilter) (-1) were obtained. Nevertheless, production of biopolymers caused non-uniform distribution flow rates that reduced the performance. Residence time distribution profiles showed an intermediate dispersion flow rate with a dispersion coefficient of 0.8 cm(2) s(-1).
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Contaminantes Atmosféricos/metabolismo , Alcanos/metabolismo , Reactores Biológicos , Filtración , Éteres Metílicos/metabolismo , Pseudomonas aeruginosa/metabolismo , Biodegradación Ambiental , Cromatografía de Gases , Gasolina/análisis , Hexanos/metabolismo , CinéticaRESUMEN
OBJECTIVE: Despite the development of endovascular procedures, open repair remains the gold standard for the treatment of aortic thoracoabdominal aneurysms and some type B dissections, with well-established good outcomes and long-term durability at high-volume centers. The present study described and analyzed public data from patients treated in the public system in a 12-year interval, in a city where more than 5 million inhabitants depend on the Public Health System. METHODS: Public data from procedures performed between 2008 and 2019 were extracted using web scraping techniques. The variables available in the database include sex, age, elective or emergency hospital admission, number of surgeries, in-hospital mortality, length of stay, and information on reimbursement values. RESULTS: A total of 556 procedures were analyzed. Of these, 60.79% patients were men, and 41.18% were 65 years of age or older. Approximately 60% had a residential address registered in the municipality. Of all surgeries, 65.83% were elective cases. There were 178 in-hospital deaths (mortality of 32%). In the elective context, there were 98 deaths 26.78% versus 80 deaths (42.10%) in the emergency context (p=0.174). Mortality was lower in the hospitals that performed more surgeries. A total of USD 3,038,753.92 was paid, an average of USD 5,406.95 for elective surgery and USD 5,074.76 for emergency surgery (p=0.536). CONCLUSION: Mortality was no different between groups, and hospitals with higher volume presented more favorable outcomes. Specialized referral centers should be considered by health policy makers.
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Aneurisma de la Aorta Abdominal , Aneurisma de la Aorta Torácica , Aneurisma de la Aorta Abdominal/cirugía , Aneurisma de la Aorta Torácica/epidemiología , Aneurisma de la Aorta Torácica/cirugía , Brasil/epidemiología , Humanos , Tiempo de Internación , Masculino , Salud PúblicaRESUMEN
INTRODUCTION: Although endovascular correction is a promising perspective, the gold-standard treatment for thoracoabdominal aortic aneurisms and type-B dissections with visceral involvement remains open surgery, particularly due to its well-established long-term durability. This study aims to describe and evaluate public data from patients treated for thoracoabdominal aortic aneurism in the Brazilian public health system in a 12-year interval. METHODS: Data from procedures performed between 2008 and 2019 were extracted from the national public database (Departamento de Informática do Sistema Único de Saúde, or DATASUS) using web scraping techniques. Procedures were evaluated regarding the yearly frequency of elective or urgency surgeries, in-hospital mortality, and governmental costs. All tests were done with a level of significance P<0.05. RESULTS: A total of 812 procedures were analyzed. Of all surgeries, 67.98% were elective cases. There were 328 in-hospital deaths (mortality of 40.39%). In-hospital mortality was lower in elective procedures (26.92%) than in urgency procedures (46.74%) (P=0.008). Total governmental expenditure was $3.127.051,56 - an average of $3.774,22 for elective surgery and $3.791,93 for emergency surgery (P=0.999). CONCLUSION: The proportion of urgency procedures is higher than that recommended by international literature. Mortality was higher for urgent admissions, although governmental costs were equal for elective and urgent procedures; specialized referral centers should be considered by health policy makers.
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Aneurisma de la Aorta Torácica , Disección Aórtica , Implantación de Prótesis Vascular , Procedimientos Endovasculares , Humanos , Aneurisma de la Aorta Torácica/cirugía , Aneurisma de la Aorta Torácica/etiología , Disección Aórtica/cirugía , Implantación de Prótesis Vascular/métodos , Salud Pública , Brasil/epidemiología , Procedimientos Endovasculares/métodos , Resultado del Tratamiento , Estudios Retrospectivos , Complicaciones Posoperatorias/etiologíaRESUMEN
Superior vena cava aneurysms are rare mediastinal vascular lesions. Aneurysms are classified as fusiform and saccular, with the latter being rarer than the former. We report the case of an asymptomatic 75-year-old woman who presented with a superior mediastinal mass. She underwent chest computed tomography angiography, which demonstrated a saccular aneurysm in the superior vena cava.
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Aneurisma , Enfermedades del Mediastino , Anciano , Aneurisma/diagnóstico por imagen , Aneurisma/cirugía , Femenino , Humanos , Mediastino/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Vena Cava Superior/diagnóstico por imagenRESUMEN
The microalga Scenedesmus obtusiusculus AT-UAM efficiently captured CO2 from two flue gas streams in a hybrid photobioreactor located in a greenhouse. Uptake rates of CO2, NO, and SO2 from a formulated gas stream were 160.7 mg L-1 day-1, 0.73 mg L-1 day-1, and 1.56 mg L-1 day-1, respectively, with removal efficiencies of 100% for all gases. Exhaust gases of a motor generator were also removed with uptake rates of 111.4 mg L-1 day-1, 0.42 mg L-1 day-1, and 0.98 mg L-1 day-1, obtaining removal efficiencies of 77%, 71%, and 53% for CO2, NOx, and SO2, respectively. On average, 61% of the CO2 from both flue gas streams was assimilated as microalgal biomass. The maximum CO2 uptake rate of 182 mg L-1 day-1 was achieved for formulated flue gas flow rate above 100 mL min-1. The biomass recovery of 88% was achieved using a 20-L electro-coagulation-flotation chamber coupled to a settler with a low specific power consumption of 0.27 kWh kg-1. The photobioreactor was operated for almost 7 months without contamination of invasive species or a decrease in the activity. It is a very encouraging result for long-term operation in flue gas treatment.
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Microalgas , Scenedesmus , Biomasa , Dióxido de Carbono , Gases , FotobiorreactoresRESUMEN
This work evaluated the effect of different initial biomass ratios in a co-culture of an alkaliphilic methanotrophic bacteria consortium (AMB) and the green microalga Scenedesmus obtusiusculus (GM) on the maximum CH4 specific biodegradation rate and global carbon uptake. The highest maximum specific biodegradation rate was 589 ± 0.01 mgCH4 gbiomass-1 d-1 obtained for a proportion of 3:1 AMB-GM (w w-1) and 8% of initial CH4 in the headspace. The methane degradation rate was 1.5 times lower than the value obtained solely by the AMB consortium, and it was associated with pH increases due to the evolved CO2 consumption by the microalga. Increased activity of the AMB consortium along the experiments was due to progressive adaptation. Massive sequencing revealed the presence of methanotrophic/methylotrophic species such as Methylocystis sp., Methylomicrobium sp., Methylophaga sp., and Hyphomicrobium sp. Successful complete methane and carbon dioxide uptake was obtained with the 3:1, 4:1, and 5:1 AMB-GM biomass ratios, while for the rest of the ratios tested, more than 70% of the initial methane was transformed into biomass and inorganic carbon. This study showed that methanotrophic-microalgal co-cultures lead to a promising strategy for greenhouse gases mitigation in one step.
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Biodegradación Ambiental , Gases de Efecto Invernadero , Metano/metabolismo , Microalgas/fisiología , Biomasa , Dióxido de Carbono/metabolismo , Técnicas de Cocultivo , Methylocystaceae , Microalgas/metabolismo , Scenedesmus/metabolismoRESUMEN
Rhinocladiella similis biodegraded volatile organic compounds (VOCs) of different polarity in gas-phase biofilters. Elimination capacities, (EC) of 74 g(hexane) m(-3) h(-1), 230 g(ethanol) m(-3) h(-1), 85 g(toluene) m(-3) h(-1) and 30 g(phenol) m(-3) h(-1) were obtained. EC values correlated with the solubility of the VOCs. R. similis grown with n-hexane or ethanol in biofilters packed with Perlite showed that the surface hydrophobicity was higher with n-hexane than ethanol. The hydrophobin-like proteins extracted from the mycelium produced with n-hexane (15 kDa) were different from those in the ethanol biofilter (8.5 kDa and 7 kDa).
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Antifúngicos/metabolismo , Antifúngicos/farmacología , Ascomicetos/efectos de los fármacos , Ascomicetos/metabolismo , Estrés Fisiológico , Compuestos Orgánicos Volátiles/metabolismo , Compuestos Orgánicos Volátiles/farmacología , Biotransformación , Proteínas Fúngicas/química , Proteínas Fúngicas/aislamiento & purificación , Interacciones Hidrofóbicas e Hidrofílicas , Proteínas de la Membrana/química , Proteínas de la Membrana/aislamiento & purificación , Peso MolecularRESUMEN
Biodegradation of methyl tert-butyl ether (MTBE) by cometabolism has shown to produce recalcitrant metabolic intermediates that often accumulate. In this work, a consortium containing Pseudomonads was studied for its ability to fully degrade oxygenates by cometabolism. This consortium mineralized MTBE and TBA with C3-C7 n-alkanes. The highest degradation rates for MTBE (75 +/- 5 mg g(protein) (-1) h(-1)) and TBA (86.9 +/- 7.3 mg g(protein) (-1) h(-1)) were obtained with n-pentane and n-propane, respectively. When incubated with radiolabeled MTBE and n-pentane, it converted more than 96% of the added MTBE to (14)C-CO(2). Furthermore, the consortium degraded tert-amyl methyl ether, tert-butyl alcohol (TBA), tert-amyl alcohol, ethyl tert-butyl ether (ETBE) when n-pentane was used as growth source. Three Pseudomonads were isolated but only two showed independent MTBE degradation activity. The maximum degradation rates were 101 and 182 mg g(protein) (-1) h(-1) for Pseudomonas aeruginosa and Pseudomonas citronellolis, respectively. The highest specific affinity (a degrees (MTBE)) value of 4.39 l g(protein) (-1) h(-1) was obtained for Pseudomonas aeruginosa and complete mineralization was attained with a MTBE: n-pentane ratio (w/w) of 0.7. This is the first time that Pseudomonads have been reported to fully mineralize MTBE by cometabolic degradation.
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Alcanos/metabolismo , Gasolina , Éteres Metílicos/metabolismo , Pseudomonas/metabolismo , Cromatografía de Gases , Medios de CultivoRESUMEN
Resumo A doença cerebrovascular extracraniana tem sido intensamente investigada em todo o mundo, sendo tema de suma importância para os cirurgiões vasculares. A presente Diretriz foi elaborada pela Sociedade Brasileira de Angiologia e Cirurgia Vascular (SBACV) em sucessão à Diretriz de 2015. As doenças de etiologia não ateroscleróticas não foram incluídas nesse documento. O objetivo desta Diretriz é congregar as evidências mais robustas nessa área para auxiliar os especialistas no processo decisório do tratamento. Foi utilizada a metodologia AGREE II e o sistema da Sociedade Europeia de Cardiologia para as recomendações e níveis de evidências. As recomendações foram graduadas de I a III, e os níveis de evidência classificados em A, B e C. A presente Diretriz foi dividida em 11 capítulos, que tratam dos vários aspectos da doença cerebrovascular extracraniana: diagnóstico, tratamentos e complicações, de forma atualizada e com as recomendações propostas pela SBACV.
Abstract Extracranial cerebrovascular disease has been the subject of intense research throughout the world, and is of paramount importance for vascular surgeons. This guideline, written by the Brazilian Society of Angiology and Vascular Surgery (SBACV), supersedes the 2015 guideline. Non-atherosclerotic carotid artery diseases were not included in this document. The purpose of this guideline is to bring together the most robust evidence in this area in order to help specialists in the treatment decision-making process. The AGREE II methodology and the European Society of Cardiology system were used for recommendations and levels of evidence. The recommendations were graded from I to III, and levels of evidence were classified as A, B, or C. This guideline is divided into 11 chapters dealing with the various aspects of extracranial cerebrovascular disease: diagnosis, treatments and complications, based on up-to-date knowledge and the recommendations proposed by SBACV.
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Microalgae are among the most productive biological systems for converting sunlight into chemical energy, which is used to capture and transform inorganic carbon into biomass. The efficiency of carbon dioxide capture depends on the cultivation system configuration (photobioreactors or open systems) and can vary according to the state of the algal physiology, the chemical composition of the nutrient medium, and environmental factors such as irradiance, temperature and pH. This mini-review is focused on some of the most important environmental factors determining photosynthetic activity, carbon dioxide biofixation, cell growth rate and biomass productivity by microalgae. These include carbon dioxide and O2 concentrations, light intensity, cultivation temperature and nutrients. Finally, a review of the operation of microalgal cultivation systems outdoors is presented as an example of the impact of environmental conditions on biomass productivity and carbon dioxide fixation.
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Reactores Biológicos , Dióxido de Carbono/metabolismo , Ambiente , Microalgas/metabolismo , Concentración de Iones de Hidrógeno , Luz , Microalgas/crecimiento & desarrollo , Microalgas/fisiología , Nutrientes/metabolismo , Oxígeno/metabolismo , Fotosíntesis , TemperaturaRESUMEN
Scenedesmus obtusiusculus AT-UAM, isolated from Cuatro Ciénegas wetlands in Mexico was taxonomically, molecularly and biochemically compared to S. obtusiusculus CCAP 276/25 (Culture Collection of Algae and Protozoa, Scotland, UK). Analysis of Internal Transcribed Spacer 2 (ITS2) secondary structures confirmed that the mexican strain belongs to S. obtusiusculus with one change in the ITS2 nucleotide sequence. However, both strains exhibited different biochemical and fatty acid profiles and therefore biotechnological potential, emphasizing the need for deeper studies among strains of the same species. Furthermore, the biochemical variations of S. obtusiusculus AT-UAM under nitrogen starvation and different levels of irradiance were evaluated. The maximum lipid production (1730â¯mgâ¯L-1) was obtained at 613⯵molâ¯m-2â¯s-1 while the highest carbohydrate content (49%) was achieved at 896⯵molâ¯m-2â¯s-1. Additionally, this strain was capable of storing lipids (â¼52%) and carbohydrates (â¼40%) under outdoor condition depending on the light availability in the cultivation broth.
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The extensive microalgae diversity offers considerable versatility for a wide range of biotechnological applications in environmental and production processes. Microalgal cultivation is based on CO2 fixation via photosynthesis and, consequently, it is necessary to evaluate, in a short time and reliable way, the effect of the CO2 gas concentration on the consumption rate and establish the tolerance range of different strains and the amount of inorganic carbon that can be incorporated into biomass in order to establish the potential for industrial scale application. Dynamic experiments allow calculating the short-term microalgal photosynthetic activity of strains in photobioreactors. In this paper, the effect of step-changes in CO2 concentration fed to a 20L bubble column photobioreactor on the CO2 consumption rate of Scenedesmus obtusiusculus was evaluated at different operation times. The highest apparent CO2 consumption rate (336µmolm-2s-1 and 5.6% of CO2) was 6530mgCO2gb-1d-1 and it decreased to 222mgCO2gb-1d-1 when biomass concentration increased of 0.5 to 3.1gbL-1 and 5.6% of CO2 was fed. For low CO2 concentrations (<3.8%) the pH remained close to the optimal value (7.5 and 8). The CO2 consumption rates show that S. obtusiusculus was not limited by CO2 availability for concentrations above of 3.8%. The CO2 mass balance showed that 90% of the C-CO2 transferred was used for S. obtusiusculus growth.
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Dióxido de Carbono/metabolismo , Fotobiorreactores , Scenedesmus/metabolismo , Biomasa , Microalgas/metabolismoRESUMEN
A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L-1 under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-ß-hydroxybutyrate (PHB) content (308±2mgPHB gdw-1) compared to continuous illumination. The highest PHB content by IZT culture was 178±10mgPHB gdw-1 under 15:15min light-dark cycles. PCR-DGGE analysis revealed that the IZT culture was mainly composed of Rhodopseudomonas palustris identified with high nucleotide similarity (99%). The evaluated cultures might be used for hydrogen and PHB production. They might provide energy savings by using light-dark cycles and DFE valorization.