Effect of nitrogen limitation on starch accumulation in Chlorella vulgaris

Due to the limited stocks of fossil fuels and the production of greenhouse gas carbon dioxide on their combustion alternative sources of energy are being investigated. Recently, microalgae have received much attention as a renewable energy resource because these photosynthetic microorganisms can convert sunlight, water and CO2 into potential biofuels (1). The microalga Chlorella vulgaris, particularly, has been considered as a potential raw material for bioethanol production because it can accumulates high levels of starch when grown under optimized culture conditions (2). The aim of the present work was to study the effect of nitrogen limitation on starch production by the microalgae C. vulgaris. C. vulgaris CCAP 211/1e (P12 strain) was obtained from the Culture Collection of Algal Laboratory, Institute of Botany, Academy of Sciences of the Czech Republic. The original (nitrogen sufficient) growth medium based on the elementary composition of algal biomass had the following initial composition (mg l−1): 1,100 (NH2) 2CO, 237 KH2PO4, 204 MgSO4∙7H2O, 40 C10H12O8N2NaFe, 88 CaCl2, 0.83 H3BO3, 0.95 CuSO4∙5H2O, 3.3 MnCl2∙4H2O, 0.17 (NH4) 6Mo7O24∙4H2O, 2.7 ZnSO4∙7H2O, 0.6 CoSO4∙7H2O, and 0.014 NH4VO3 in distilled water (3). Nitrogen limited growth medium was formulated by omitting urea from the original growth medium. The microalgae were grown in 1 l Schott flasks with 0.4 l of medium. Cultures were maintained at 30ºC under continuous, cool white fluorescent lamps. Light intensity was approximately 100 mmol m‐2 s‐1 at the surface of the photobioreactors. The concentration of suspended algal biomass was determined by optical density measurement at 700 nm. Starch content in the microalgae was determined colorimetrically by the anthrone reaction. The results showed that starch accumulation in C. vulgaris was strongly related to nitrogen concentration. Under nitrogen limited growth conditions, starch constituted 36% of the algal biomass after 118 h of cultivation, whereas nitrogen sufficient microalgae contained 8% of their dry weight as starch. On the other hand, nitrogen sufficient condition led to an increase in biomass concentration, with the highest biomass concentration of 2.06 g l‐1. It can be concluded that accumulation of starch is enhanced in nitrogen limited cultures of C. vulgaris P12

Mixotrophic cultivation of Chlorella vulgaris using industrial dairy waste as organic carbon source

Growth parameters and biochemical composition of the green microalga Chlorella vulgaris cultivated under different mixotrophic conditions were determined and compared to those obtained from a photoautotrophic control culture. Mixotrophic microalgae showed higher specific growth rate, final biomass concentration and productivities of lipids, starch and proteins than microalgae cultivated under photoautotrophic conditions. Moreover, supplementation of the inorganic culture medium with hydrolyzed cheese whey powder solution led to a significant improvement in microalgal biomass production and carbohydrate utilization when compared with the culture enriched with a mixture of pure glucose and galactose,due to the presence of growth promoting nutrients in cheese whey. Mixotrophic cultivation of C.vulgaris using the main dairy industry by-product could be considered a feasible alternative to reduce the costs of microalgal biomass production, since it does not require the addition of expensive carbohydrates to the culture mediumThis study was supported by the grants SFRH/BD/44724/2008 (Bruno Fernandes) and SFRH/BPD/44935/2008 (Giuliano Dragone) from Fundacao para a Ciencia e a Tecnologia (Portugal). The authors also acknowledge the financial support received through the projects INNOVALGAE (FCT PTDC/AAC-AMB/108511/2008) and ALGANOL

Nutrient limitation as a strategy for increasing starch accumulation in microalgae

Increasing microalgal starch content by nutrient limitation has been regarded as an affordable approach for the production of third generation bioethanol. This work evaluated starch accumulation in Chlorella vulgaris P12 under different initial concentrations of nitrogen (0–2.2 g urea L−1) and iron (0–0.08 g FeNa-EDTA L−1) sources, using a central composite design (CCD) for two factors. The obtained model: Starch content (%) = 8.220 − 16.133X1 + 13.850, relating starch accumulation in microalgae with the coded level for initial urea concentration in the growth medium (X1) presented a good concordance between the predicted and experimental values (R2 = 0.94). Since accumulation of starch occurred at nitrogen depletion conditions under which the cell growth was much slower than that observed during nitrogen supplemented cultivations, a two-stage cultivation process for high starch accumulation (>40%) and cell growth of C. vulgaris was proposed: a first cultivation stage using nitrogen- and iron-supplemented medium (initial urea and FeNa-EDTA concentrations of 1.1 and 0.08 g L−1, respectively), followed by a second cultivation stage in a nitrogen- and iron-free medium. The high starch content obtained suggests C. vulgaris P12 as a very promising feedstock for bioethanol production.This research work was supported by the Grants SFRH/BPD/44935/2008 (Giuliano Dragone) and SFRH/BD/44724/2008 (Bruno Fernandes) from Fundacao para a Ciencia e a Tecnologia (Portugal). The authors also acknowledge the financial support received through the projects INNOVALGAE (FCT PTDC/AAC-AMB/108511/2008) and ALGANOL

Starch determination in Chlorella vulgaris-a comparison between acid and enzymatic methods

Different methods for estimating starch in Chlorella vulgaris were compared with the view of establishing a procedure suitable for rapid and accurate determination of starch content in this microalgal species. A close agreement was observed between methods that use perchloric acid and enzymatic methods that use α-amylase and amyloglucosidase to hydrolyze the starch of microalgae grown under different nitrogen culture conditions. Starch values obtained by these methods were significantly higher than those estimated by using hydrochloric acid as solubilizing and hydrolyzing agent. The enzymatic method (EM1) proved to be the most rapid and precise method for microalgal starch quantification. Furthermore, the evaluation of resistant starch by enzymatic methods assayed in nitrogen-sufficient and nitrogen-starved cells showed that no formation of this type of starch occurred in microalgae, meaning that this should not interfere with starch content determinations.This research work was supported by the grants SFRH/BD/44724/2008 (Bruno Fernandes) from Fundacao para a Ciencia e a Tecnologia (Portugal) and SFRH/BPD/44935/2008 (Giuliano Dragone). The authors also acknowledge the financial support received through the projects INNOVALGAE (FCT PTDC/AAC-AMB/108511/2008) and ALGANOL

Cardiovascular risk factors in adult general out-patient clinics in Nigeria: a country analysis of the Africa and Middle East Cardiovascular Epidemiological (ACE) study.

Background: With globalization and rapid urbanization, demographic and epidemiologic transitions have become important determinants for the emergence of cardiovascular disease (CVD).Objective: To estimate the prevalence of CVD risk factors in adult out-patients attending general practice and non-specialist clinics in urban and rural Nigeria.Methods: As part of the Africa and Middle East Cardiovascular Epidemiological (ACE) study, a cross-sectional epidemiologic study was undertaken for the presence of hypertension, diabetes mellitus, dyslipidemia, obesity, smoking and abdominal obesity in Nigeria.Results: In total, 303 subjects from 8 out-patient general practice clinics were studied, 184 (60.7%) were female and 119 (39.3%) were male. Mean age was 42.7±13.1 years; 51.8% were aged <45 years; 4% ≥65 years. Over 90% of subjects had ≥1 of 6 selected modifiable cardiovascular risk factors: 138 (45.6%) had 1-2; 65 (21.5%) had 3; 60 (19.8%) had 4; and 11 (3.6%) had 5 concurrent risk factors. Screening identified 206 subjects (68.0%) with dyslipidemia who did not have a prior diagnosis.Conclusion: Cardiovascular risk factors are highly prevalent in Nigerian subjects attending out-patient clinics. Moreover, many subjects were undiagnosed and therefore unaware of their cardiovascular risk status. Opportunistic screening alongside intensive national, multisectoral education or risk factor education is needed, should be scaled up nationwide and rolled out in both urban and rural communities in Nigeria.Keywords: Nigeria, cardiovascular risk factors, screening programs, risk factor management, The Africa and Middle East Cardiovascular Epidemiological (ACE) study

Adiposity indicators and cardiovascular risk factors in Azorean adolescents

This study was conducted to evaluate the association of adiposity indicators (body mass index, waist circumference and waist-to-height ratio) with cardiovascular risk factors in lean andobese Azorean adolescents.info:eu-repo/semantics/publishedVersio

Photocatalytic activity of TiO2/graphene and TiO2/graphene oxide nanocomposites

Semiconductor-based heterogeneous photocatalysis has been one of the most promising processes for the treatment of contaminated water. Among the available catalysts, titanium dioxide (TiO2) presents the best photocatalytic properties, being chemically and biologically inert, stable, non-toxic, cheap and easy to produce. However, its energy bang gap lies in the ultraviolet (UV) range, which is responsible for a reduced spectral activation, since UV radiation corresponds to only 5% of the solar spectrum [1]. For this reason, one of the main purposes of the scientific community has been to improve the photocatalytic performance of TiO2, namely through an adequate doping of this material, or through the creation of nanocomposites, to enable photocatalysis occurrence by the incidence of visible light. One alternative concerns the application of nanocomposites of TiO2 with graphene and graphene oxide to photocatalytic processes [2]. In this work, nanocomposites of TiO2 with different weight concentrations of graphene and graphene oxide (namely 0.5%, 1%, 1.5% and 3%) were synthetized by a one-step hydrothermal method and characterized in terms of morphology, crystalline structure, vibrational modes and optical band gap. The photocatalytic activity of these nanocomposites was then evaluated through the degradation of methylene blue and ciprofloxacin solutions under UV and visible radiation. The results indicated that the studied nanocomposites presented higher degradation rates of the methylene blue than the pure TiO2, which increased with the content of graphene/graphene oxide. However, these composites proved to be less suitable to degrade the ciprofloxacin solution than the pure TiO2 nanoparticles.Portuguese Foundation for Science and Technology (FCT) - UID/FIS/04650/2013, PTDC/CTM-ENE/5387/2014 and SFRH/BD/98616/2013; Basque Government Industry Department under the ELKARTEK Program.info:eu-repo/semantics/publishedVersio

Nanoliposomes for encapsulation and delivery of the potential antitumoral methyl 6-methoxy-3-(4-methoxyphenyl)-1H-indole-2-carboxylate

A potential antitumoral fluorescent indole derivative, methyl 6-methoxy-3-(4-methoxyphenyl)-1H-indole-2-carboxylate, was evaluated for the in vitro cell growth inhibition on three human tumor cell lines, MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), and NCI-H460 (non-small cell lung cancer), after a continuous exposure of 48 h, exhibiting very low GI50 values for all the cell lines tested (0.25 to 0.33 µM). This compound was encapsulated in different nanosized liposome formulations, containing egg lecithin (Egg-PC), dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylglycerol (DPPG), DSPC, cholesterol, dihexadecyl phosphate, and DSPE-PEG. Dynamic light scattering measurements showed that nanoliposomes with the encapsulated compound are generally monodisperse and with hydrodynamic diameters lower than 120 nm, good stability and zeta potential values lower than −18 mV. Dialysis experiments allowed to monitor compound diffusion through the lipid membrane, from DPPC/DPPG donor liposomes to NBD-labelled lipid/DPPC/DPPG acceptor liposomes.Thanks are due to the Foundation for Science and Technology (FCT, Portugal) for financial support through the research centers (CFUM and CQ-UM) and project PTDC/QUI/81238/2006 (cofinanced by FEDER/COMPETE, ref. FCOMP-01-0124-FEDER-007467). A.S. Abreu (SFRH/BPD/24548/2005) and L. Vale-Silva (SFRH/BPD/29112/2006) acknowledge FCT for their postdoctoral grants

Manejo de via aérea no paciente obeso: uma revisão de literatura

Introduction: Airway management in obese patients is a concern for anesthesiologists. This procedure is more difficult in this population due to anatomical and physiological changes caused by excess fat. Obese patients have pulmonary alterations that may lead to faster desaturation, which makes this group more susceptible to complications during tracheal intubation. Objective: To understand which factors are responsible for the higher incidence of difficult airway in obese patients. Methods: A survey on the DeCS platform, followed by PubMed and SciELO was carried out to identify articles related to the topic, including Randomized Clinical Trials, Systematic Reviews, Meta-Analysis and Books and Documents. A total of 20 articles in Portuguese, English and Spanish were selected. Results: Of the analyzed studies, three identified Mallampati III/IV, reduced mobility of cervical spine and limited mouth opening as risk factors for difficult airway. One study identified neck circumference as an associated factor, while the others stated that there is no relationship between neck circumference and difficult airway. Conclusion: There was no consensus in the literature regarding the risk factors for difficult airway. It is necessary to develop retrospective studies that analyze patients with difficult airway and complications, determining which factors were present and affected the procedure.Introdução: O manejo de vias aéreas do paciente obeso é uma preocupação dos anestesiologistas. Tal procedimento mostra-se mais difícil se comparado aos demais pacientes devido a alterações anatômicas e fisiológicas causadas pelo excesso de gordura. O paciente obeso possui alterações na função pulmonar que favorecem uma dessaturação mais rápida do que as demais pessoas, o que torna esse grupo mais suscetível a complicações durante a intubação orotraqueal. Objetivo: Compreender quais fatores são responsáveis pela maior incidência de via aérea difícil nos pacientes obesos. Métodos: Foi realizada busca na plataforma DeCS e em seguida PubMed e SciELO para levantamento de artigos relacionados ao tema, sendo incluídos Ensaios Clínicos Randomizados, Revisões Sistemáticas, Meta-Análises e Livros e Documentos, sendo eleitos 20 artigos totais, em português, inglês e espanhol. Resultado: Dos estudos analisados, três encontraram fatores de risco para VA difícil como Mallampati III/IV, menor mobilidade do pescoço e menor abertura da boca. Um apontou circunferência do pescoço como fator influenciador enquanto outro afirmou que não há relação da circunferência com a dificuldade em se obter uma VA definitiva. Conclusão: Não houve consenso na literatura quanto aos fatores de risco para uma VA difícil. É necessário o desenvolvimento de estudos retrospectivos que analisem pacientes com ocorrência de VA difícil e complicações para que se possa levantar quais fatores estavam presentes em cada caso e como influenciaram