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1.
Enferm Infecc Microbiol Clin ; 41(2): 70-78, 2023 Feb.
Artigo em Espanhol | MEDLINE | ID: mdl-34305229

RESUMO

Objective: To compare the clinical characteristics, treatments, and evolution of critical patients with COVID-19 pneumonia treated in intensive care units (ICU) after one year of pandemic. Methodology: Multicenter, prospective study, which included critical COVID-19 patients in 9 ICUs in northwestern Spain. The clinical characteristics, treatments, and evolution of patients admitted to the ICU during the months of March-April 2020 (period 1) were compared with patients admitted in January-February 2021 (period 2). Results: 337 patients were included (98 in period 1 and 239 in period 2). In period 2, fewer patients required invasive mechanical ventilation (IMV) (65% vs. 84%, P < .001), using high-flow nasal cannulas (CNAF) more frequently (70% vs. 7%, P < .001), ventilation non-invasive mechanical (NIMV) (40% vs. 14%, P < .001), corticosteroids (100% vs. 96%, P = .007) and prone position in both awake (42% vs. 28%, P = .012), and intubated patients (67% vs. 54%, P = .034). The days of IMV, ICU stay and hospital stay were lower in period 2. Mortality was similar in the two periods studied (16% vs. 17%). Conclusions: After one year of pandemic, we observed that in patients admitted to the ICU, CNAF, NIMV, use of the prone position, and corticosteroids have been used more frequently, reducing the number of patients in IMV, and the length of stay in the ICU and hospital stay. Mortality was similar in the two study periods.

2.
Int J Mol Sci ; 23(18)2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36142623

RESUMO

Recently, the field of polymer nanocomposites has been an area of high scientific and industrial attention due to noteworthy improvements attained in these materials, arising from the synergetic combination of properties of a polymeric matrix and an organic or inorganic nanomaterial. The enhanced performance of those materials typically involves superior mechanical strength, toughness and stiffness, electrical and thermal conductivity, better flame retardancy and a higher barrier to moisture and gases. Nanocomposites can also display unique design possibilities, which provide exceptional advantages in developing multifunctional materials with desired properties for specific applications. On the other hand, machine learning (ML) has been recognized as a powerful predictive tool for data-driven multi-physical modelling, leading to unprecedented insights and an exploration of the system's properties beyond the capability of traditional computational and experimental analyses. This article aims to provide a brief overview of the most important findings related to the application of ML for the rational design of polymeric nanocomposites. Prediction, optimization, feature identification and uncertainty quantification are presented along with different ML algorithms used in the field of polymeric nanocomposites for property prediction, and selected examples are discussed. Finally, conclusions and future perspectives are highlighted.


Assuntos
Nanocompostos , Gases , Aprendizado de Máquina , Polímeros
3.
Int J Technol Assess Health Care ; 37(1): e63, 2021 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-33942712

RESUMO

The Monitoring Studies (MS) program, the approach developed by RedETS to generate postlaunch real-world evidence (RWE), is intended to complement and enhance the conventional health technology assessment process to support health policy decision making in Spain, besides informing other interested stakeholders, including clinicians and patients. The MS program is focused on specific uncertainties about the real effect, safety, costs, and routine use of new and insufficiently assessed relevant medical devices carefully selected to ensure the value of the additional research needed, by means of structured, controlled, participative, and transparent procedures. However, despite a clear political commitment and economic support from national and regional health authorities, several difficulties were identified along the development and implementation of the first wave of MS, delaying its execution and final reporting. Resolution of these difficulties at the regional and national levels and a greater collaborative impulse in the European Union, given the availability of an appropriate methodological framework already provided by EUnetHTA, might provide a faster and more efficient comparative RWE of improved quality and reliability at the national and international levels.


Assuntos
Tomada de Decisões , Avaliação da Tecnologia Biomédica , Custos e Análise de Custo , Humanos , Reprodutibilidade dos Testes , Espanha
4.
Genomics ; 112(2): 1916-1925, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31759118

RESUMO

This paper presents a Grouping Genetic Algorithm (GGA) to solve a maximally diverse grouping problem. It has been applied for the classification of an unbalanced database of 801 samples of gene expression RNA-Seq data in 5 types of cancer. The samples are composed by 20,531 genes. GGA extracts several groups of genes that achieve high accuracy in multiple classification. Accuracy has been evaluated by an Extreme Learning Machine algorithm and was found to be slightly higher in balanced databases than in unbalanced ones. The final classification decision has been made through a weighted majority vote system between the groups of features. The proposed algorithm finally selects 49 genes to classify samples with an average accuracy of 98.81% and a standard deviation of 0.0174.


Assuntos
Neoplasias/genética , RNA-Seq/métodos , Aprendizado de Máquina não Supervisionado , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias/classificação , RNA-Seq/normas
5.
Biomacromolecules ; 21(4): 1568-1577, 2020 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-32163275

RESUMO

The production of paper-based bacterial cellulose-chitosan (BC-Ch) nanocomposites was accomplished following two different approaches. In the first, BC paper sheets were produced and then immersed in an aqueous solution of chitosan (BC-ChI); in the second, BC pulp was impregnated with chitosan prior to the production of paper sheets (BC-ChM). BC-Ch nanocomposites were investigated in terms of physical characteristics, antimicrobial and antioxidant properties, and the ability to inhibit the formation of biofilms on their surface. The two types of BC-Ch nanocomposites maintained the hydrophobic character, the air barrier properties, and the high crystallinity of the BC paper. However, BC-ChI showed a surface with a denser fiber network and with smaller pores than those of BC-ChM. Only 5% of the chitosan leached from the BC-Ch nanocomposites after 96 h of incubation in an aqueous medium, indicating that it was well retained by the BC paper matrix. BC-Ch nanocomposites displayed antimicrobial activity, inhibiting growth of and having a killing effect against bacteria Staphylococcus aureus and Pseudomonas aeruginosa and yeast Candida albicans. Moreover, BC-Ch papers showed activity against the formation of a biofilm on their surface. The incorporation of chitosan increased the antioxidant activity of the BC paper. Paper-based BC-Ch nanocomposites combined the physical properties of BC paper and the antimicrobial, antibiofilm, and antioxidant activities of chitosan.


Assuntos
Quitosana , Nanocompostos , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Bactérias , Celulose , Quitosana/farmacologia
6.
J Ultrasound Med ; 38(11): 3073-3077, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30887558

RESUMO

Intrauterine devices (IUDs) are among the most efficient and widely used contraceptive methods available. Removal is recommended after a certain time or in some cases when adverse effects are observed. A considerable number of patients have nonvisible guides or "lost threads" on speculum examinations, hindering the extraction. In this article, we report a consecutive series of 254 nonpregnant patients referred to our center after 1 or more failed attempts at IUD removal. We describe a novel ultrasound-guided approach, using a laparoscopic forceps to safely and effectively remove IUDs in nonpregnant patients.


Assuntos
Remoção de Dispositivo/métodos , Dispositivos Intrauterinos , Ultrassonografia de Intervenção/métodos , Útero/diagnóstico por imagem , Adulto , Endoscopia , Feminino , Humanos , Estudos Retrospectivos , Instrumentos Cirúrgicos
7.
Gastroenterol Hepatol ; 42 Suppl 1: 26-33, 2019 Sep.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-32560770

RESUMO

TThe incorporation of direct-acting antiviral agents to the treatment of chronic hepatitis C infection has simplified diagnosis and follow-up, allowing optimisation of health resources (consultations and tests) dedicated to the management of the disease. The aim of this study was to estimate the economic impact of this simplification. Health resource optimisation was estimated through the Delphi method, based on a panel of 36 experts, consisting of Spanish clinicians, and on clinical practice guidelines. The unit costs (€ in 2017) of the health resources included were obtained from Spanish sources. Simplification of the process, as well as liaison between the medical specialist, nurses and the pharmacy service, would generate savings of €591.17 per patient. Likewise, the mean length of consultations would be shorter with regimens of only 1 tablet daily compared with regimens of more than 1 tablet daily. Supplement information: This article is part of a supplement entitled "The value of simplicity in hepatitis C treatment", which is sponsored by Gilead. © 2019 Elsevier España, S.L.U. All rights reserved.


Assuntos
Antivirais/uso terapêutico , Custos de Cuidados de Saúde , Recursos em Saúde/economia , Hepatite C Crônica/tratamento farmacológico , Antivirais/economia , Redução de Custos , Técnica Delphi , Recursos em Saúde/normas , Necessidades e Demandas de Serviços de Saúde , Hepatite C Crônica/economia , Humanos , Guias de Prática Clínica como Assunto , Espanha
8.
Rev Med Chil ; 147(12): 1503-1509, 2019 Dec.
Artigo em Espanhol | MEDLINE | ID: mdl-32186613

RESUMO

Background During pregnancy, there is an increase in the amount of extracellular vesicles, especially placental exosomes, in maternal plasma. Aim To isolate and characterize extracellular vesicles from blood during the three trimesters of pregnancy and to evaluate their capacity to identify patients at risk of developing gestational diabetes. Material and Methods A case-control study was conducted in a cohort of 50 pregnant women with plasma samples taken in each trimester. Six women who developed gestational diabetes were paired with three healthy controls per case (a total of 19). Clinical characteristics were recorded at first prenatal appointment, and blood samples were obtained during the first, second and third trimesters. Extracellular vesicles were isolated from plasma by the commercial kit, ExoQuick™. Nanoparticle tracking analysis, was used to characterize the obtained extracellular vesicles. Results The total concentration of extracellular particles isolated from maternal plasma increased along with gestational age. The size of the extracellular vesicles obtained in the first trimester of pregnancy was very similar between groups (144 ± 37 nm for controls and 143 ± 34 nm for patients with gestational diabetes mellitus). Moreover, the concentration of extracellular vesicles collected in the first trimester, was significantly higher in patients who developed gestational diabetes mellitus later in pregnancy compared to normoglycemic pregnant women (7.94 x 10 8 and 5.15 x 10 8 , p = 0.03). Conclusions Our results provide an insight into the potential capacity of first trimester plasma extracellular vesicles as early biomarkers for the prediction of gestational diabetes mellitus.


Assuntos
Diabetes Gestacional/sangue , Vesículas Extracelulares/metabolismo , Adulto , Biomarcadores/sangue , Estudos de Casos e Controles , Diabetes Gestacional/diagnóstico , Feminino , Humanos , Valor Preditivo dos Testes , Gravidez , Estudos Prospectivos , Sensibilidade e Especificidade
9.
Sensors (Basel) ; 18(8)2018 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30115870

RESUMO

A new haptic sensor that is based on vibration produced by mechanical excitation from a clock coupled to a resonant cavity is presented. This sensor is intended to determine the chemical composition of liquid mixtures in a completely non-destructive method. In this case, a set of 23 samples of water, ethanol, and fructose mixtures has been used to simulate different kinds of alcoholic beverage. The spectral information from the vibrational absorption bands of liquid samples is analyzed by a Grouping Genetic Algorithm. An Extreme Learning Machine implements the fitness function that is able to classify the mixtures according to the concentration of ethanol and fructose. The 23 samples range from 0%⁻13% by volume of ethanol and from 0⁻3 g/L of fructose, all of them with different concentration. The new technique achieves an average classification accuracy of 96%.

10.
Gac Med Mex ; 154(1): 26-35, 2018.
Artigo em Espanhol | MEDLINE | ID: mdl-29420519

RESUMO

Objective: To assess the level of happiness and satisfaction in the life and medical practice of dermatologists in Mexico. Method: A descriptive study (online survey) was conducted focused on practicing dermatologists in our country. Questions included demographic characteristics, the Pemberton happiness index (with local validation) and questions that assessed the degree of personal satisfaction. Descriptive statistics were used to obtain the central tendency and dispersion. Measures of central tendency and dispersion were performed; to compare categorical variables, contingency tables for chi-square test were used and when comparing quantitative variables with normal distribution, Student's t t-test was used. Results: 219 surveys were included, 72.6% female and 27.4% male, with an average age of 45.6 and an average of 16 years of medical practice. Most of them (64.8%) graduate from Mexico City; 93% were very satisfied with the specialty and 98.6% of them would choose the same once again, the most important reason is to encompass medical and surgical areas. The level of happiness by using the Pemberton scale was "high" (mode: 9.11; standard deviation: 1.73). Conclusions: This first study in Latin America on this subject in dermatologists showed high levels of satisfaction and happiness in both professional and personal areas.


Objetivo: Conocer la felicidad y la satisfacción laboral de los dermatólogos en México. Método: Estudio descriptivo, mediante encuesta en línea dirigida a dermatólogos especialistas, graduados y con ejercicio en México. Se incluyeron elementos demográficos, el Índice de Felicidad de Pemberton (con validación local) y preguntas para evaluar la satisfacción personal. Se realizaron medidas de tendencia central y dispersión; para comparar las variables categóricas, se utilizaron tablas de contingencia para ji al cuadrado, y al comparar variables cuantitativas con distribución normal se utilizó la prueba t de Student. Resultados: Se incluyeron 219 encuestados, el 72.6% mujeres y el 27.4% hombres, con una media de edad de 45.6 años y un promedio de 16 años de ejercicio profesional. La mayoría (64.8%) eran egresados de la Ciudad de México y el 75.3% estaban muy satisfechos con su escuela de formación. Un 93% se manifestó muy satisfecho con su especialidad y el 98.6% volvería a escogerla; el mayor motivo sería abarcar ámbitos médicos y quirúrgicos. El grado de felicidad según el Índice de Pemberton fue «alto¼ (media: 9.11; desviación estándar: 1.73). Conclusión: Este primer estudio en América Latina sobre este aspecto en dermatólogos, muestra unos altos índices de satisfacción y felicidad, tanto en el área profesional como en la personal.


Assuntos
Dermatologistas/psicologia , Dermatologia , Felicidade , Satisfação no Emprego , Satisfação Pessoal , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
11.
Appl Microbiol Biotechnol ; 101(7): 2943-2952, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28120014

RESUMO

Cel6D from Paenibacillus barcinonensis is a modular cellobiohydrolase with a novel molecular architecture among glycosyl hydrolases of family 6. It contains an N-terminal catalytic domain (family 6 of glycosyl hydrolases (GH6)), followed by a fibronectin III-like domain repeat (Fn31,2) and a C-terminal family 3b cellulose-binding domain (CBM3b). The enzyme has been identified and purified showing catalytic activity on cellulosic substrates and cellodextrins, with a marked preference for phosphoric acid swollen cellulose (PASC). Analysis of mode of action of Cel6D shows that it releases cellobiose as the only hydrolysis product from cellulose. Kinetic parameters were determined on PASC showing a K m of 68.73 mg/ml and a V max of 1.73 U/mg. A series of truncated derivatives of Cel6D have been constructed and characterized. Deletion of CBM3b caused a notable reduction in hydrolytic activity, while deletion of the Fn3 domain abolished activity, as the isolated GH6 domain was not active on any of the substrates tested. Mutant enzymes Cel6D-D146A and Cel6D-D97A were constructed in the residues corresponding to the putative acid catalyst and to the network for the nucleophilic attack. The lack of activity of the mutant enzymes indicates the important role of these residues in catalysis. Analysis of cooperative activity of Cel6D with cellulases from the same producing P. barcinonensis strain reveals high synergistic activity with processive endoglucanase Cel9B on hydrolysis of crystalline substrates. The characterized cellobiohydrolase can be a good contribution for depolymerization of cellulosic substrates and for the deconstruction of native cellulose.


Assuntos
Celulose 1,4-beta-Celobiosidase/química , Celulose 1,4-beta-Celobiosidase/metabolismo , Paenibacillus/enzimologia , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Celulose/metabolismo , Celulose 1,4-beta-Celobiosidase/genética , Celulose 1,4-beta-Celobiosidase/isolamento & purificação , Escherichia coli/genética , Hidrólise , Cinética , Ligação Proteica , Estrutura Secundária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Deleção de Sequência , Especificidade por Substrato
12.
Appl Microbiol Biotechnol ; 100(4): 1743-1751, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26481625

RESUMO

Arabinofuranosidase Abf43A from Bacillussp. BP-7 i s a newly discovered arabinoxylan arabinofuranohydrolase (AXH). It is a modular enzyme comprised of a GH43 catalytic domain and a carbohydrate-binding module of family CBM6. Recombinant Abf43A showed high activity on arabinoxylans, being rye arabinoxylan the preferred substrate on which the purified enzyme exhibited a Km of 10.6 ± 3.3 mg/ml and a Vmax of 29.2 ± 3.4 U/mg. Thin-layer chromatography analysis of hydrolysis products showed arabinose as the only sugar released by the enzyme from its substrates. The GH43 and CBM6 modules of the enzyme were individually cloned and expressed in Escherichia coli. While the isolated catalytic GH43 module did not show hydrolytic activity, the purified CBM6 bound to soluble arabinoxylan in affinity gel electrophoresis analysis. Evaluation of cooperative activity of arabinofuranosidase Abf43A with xylanases from families GH10, GH11, andGH30, (Xyn10A, Xyn11E, and Xyn30D from Paenibacillus barcinonensis) on arabinoxylan depolymerization revealed that the studied enzyme showed synergism with Xyn11E, a 2.54-fold increase in the amount of sugars released. On the contrary, Abf43A did not show synergism with the xylanases of families GH10 or GH30 evaluated. The enzyme characterized contributes to understanding the role of this class of enzymes in the catalytic depolymerization of arabinoxylans and their potential for the production of valuable xylooligosaccharides from these abundant plant polymers.


Assuntos
Bacillus/enzimologia , Glicosídeo Hidrolases/metabolismo , Xilosidases/metabolismo , Bacillus/genética , Biotransformação , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Glicosídeo Hidrolases/genética , Hidrólise , Ligação Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Xilanos/metabolismo
13.
Biotechnol Appl Biochem ; 63(1): 51-6, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-25603884

RESUMO

The gene coding for a lichenase from Paenibacillus barcinonensis BP-23, a powerful carbohydrate-degrading strain, was obtained using a genome walking strategy and expressed in Escherichia coli for further characterization. The amino acid sequence deduced from lic16A revealed that the lichenase is a single-domain enzyme belonging to the GH16 family. Purified recombinant Lic16A showed exclusive activity on ß-1,3-1,4-glucans, showing a Km of 16.88 mg/mL and a Vmax of 266.09 U/mg using lichenan as a substrate. Lic16A was stable at 55 °C for at least 3 H in moderate pH conditions. Thin-layer chromatography analysis showed that the enzyme released a complex mixture of hydrolysis products, which consisted of different length oligosaccharides of intermediate mobility among cellooligomers. The health benefits of ß-glucans's consumption and the increased interest for the use of their oligomers as prebiotics add interest to the study of Lic16A for the production of ß-glucan-derived oligosaccharides and the evaluation of their biotechnological potential. This is the first report on ß-1,3-1,4-glucanase produced by P. barcinonensis.


Assuntos
Glucanos/metabolismo , Glicosídeo Hidrolases/metabolismo , Hordeum/metabolismo , Paenibacillus/enzimologia , Clonagem Molecular , Glucanos/química , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Hordeum/química , Hidrólise , Paenibacillus/química , Paenibacillus/genética , Paenibacillus/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
14.
Biochim Biophys Acta ; 1842(10): 1360-71, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24980978

RESUMO

Pseudomonas aeruginosa displays the ability to perform bioconversion of oleic acid into a class of hydroxylated fatty acids known as oxylipins. A diol synthase activity is responsible for such a conversion, which proceeds through the dioxygenation of oleic acid to release hydroperoxide 10-H(P)OME ((10S)-hydroxy-(8E)-octadecenoic acid), followed by conversion of the hydroperoxide intermediate into 7,10-DiHOME ((7S,10S)-dihydroxy-(8E)-octadecenoic acid), both of which accumulate in the culture supernatant. Several mutants of P. aeruginosa PAO1 were analyzed for the production of 10-H(P)OME and 7,10-DiHOME and two of them (ORFs PA2077 and PA2078), unable to release hydroxylated fatty acids, were detected and selected for further analysis. Involvement of ORFs PA2077 and PA2078 in oleate-diol synthase activity was confirmed, and their respective role in the conversion of oleic acid was analyzed by mutation complementation. Activity restoration revealed that gene PA2077 codes for the 10S-dioxygenase activity (10S-DOX) responsible for the first step of the reaction, whereas PA2078 encodes for the (7S,10S)-hydroperoxide diol synthase enzyme (7,10-DS) which allows the conversion of 10-H(P)OME into 7,10-DiHOME. Heterologous expression of both enzymes separately showed that no hetero-complex formation is required for enzymatic activity. Bioinformatics and RT-PCR analysis revealed that both genes constitute a new fine regulated oleate-diol synthase operon, originated by a gene duplication event followed by neofunctionalization for environmental adaptation, being unprecedented in prokaryotes.

15.
Pain Manag Nurs ; 16(6): 862-70, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26362406

RESUMO

Pain and discomfort during breast examination can affect a woman's adherence to breast cancer-screening programs. The aim of this study was to determine whether a nursing intervention protocol that provides verbal information and support to women could reduce pain during mammography. A randomized controlled trial of 436 Spanish women aged 50-69 who attended a breast-screening program was performed. The experimental group received a customized nursing intervention that provided face-to-face information and emotional support during the examination. Pain and anxiety were measured using a visual analogue scale and the State-Trait Anxiety Inventory, respectively. Data regarding several potential confounders were also collected. The adjusted means of pain level in the study group were obtained from multiple linear regressions, and the adjusted odds ratios (OR) and 95% confidence intervals (CI) were obtained via logistic regression. After the intervention, the level of pain was significantly lower (p = .03) in the experimental group (0.98 ± 2.28) compared with the group treated with normal care (1.48 ± 2.29). Consequently, the probability of feeling pain during mammography was lower among women in the experimental group (OR = 0.44; 95% CI: 0.24-0.81). The intervention was more effective among women with the highest anxiety levels (OR = 0.33; 95% CI: 0.11-0.98), who did not expect pain (OR = 0.28; 95% CI: 0.08-0.97), and who did not fear the outcome of the mammography (OR = 0.18; 95% CI: 0.04-0.85). Providing verbal information, as well as supporting the women during the test, is a simple and achievable intervention for nurses and can help to reduce pain during screening mammography.


Assuntos
Ansiedade/enfermagem , Neoplasias da Mama/diagnóstico por imagem , Mamografia/enfermagem , Dor/enfermagem , Educação de Pacientes como Assunto/métodos , Idoso , Feminino , Humanos , Pessoa de Meia-Idade , Modelos Estatísticos , Medição da Dor , Índice de Gravidade de Doença , Espanha
16.
BMC Biotechnol ; 14: 27, 2014 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-24755191

RESUMO

BACKGROUND: There is an increasing interest to seek new enzyme preparations for the development of new products derived from bioprocesses to obtain alternative bio-based materials. In this context, four non-commercial lipases from Pseudomonas species were prepared, immobilized on different low-cost supports, and examined for potential biotechnological applications. RESULTS: To reduce costs of eventual scaling-up, the new lipases were obtained directly from crude cell extracts or from growth culture supernatants, and immobilized by simple adsorption on Accurel EP100, Accurel MP1000 and Celite®545. The enzymes evaluated were LipA and LipC from Pseudomonas sp. 42A2, a thermostable mutant of LipC, and LipI.3 from Pseudomonas CR611, which were produced in either homologous or heterologous hosts. Best immobilization results were obtained on Accurel EP100 for LipA and on Accurel MP1000 for LipC and its thermostable variant. Lip I.3, requiring a refolding step, was poorly immobilized on all supports tested (best results for Accurel MP1000). To test the behavior of immobilized lipases, they were assayed in triolein transesterification, where the best results were observed for lipases immobilized on Accurel MP1000. CONCLUSIONS: The suggested protocol does not require protein purification and uses crude enzymes immobilized by a fast adsorption technique on low-cost supports, which makes the method suitable for an eventual scaling up aimed at biotechnological applications. Therefore, a fast, simple and economic method for lipase preparation and immobilization has been set up. The low price of the supports tested and the simplicity of the procedure, skipping the tedious and expensive purification steps, will contribute to cost reduction in biotechnological lipase-catalyzed processes.


Assuntos
Biotecnologia/métodos , Enzimas Imobilizadas/química , Lipase/química , Pseudomonas/enzimologia , Proteínas de Bactérias/química
17.
Appl Microbiol Biotechnol ; 98(13): 5949-57, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24549767

RESUMO

A new xylanase from Paenibacillus barcinonensis BP-23, Xyn11E, has been identified and characterized. Xyn11E has been cloned and heterologously expressed in Escherichia coli. It is a single-domain xylanase belonging to the family 11 of glycosyl hydrolases (GH11) with a predicted molecular weight of 20.652 kDa and an isoelectric point (pI) of 8.7. Substrate specificity, kinetic properties, and mode of action of the purified xylanase were characterized. Xyn11E exhibited high activity toward branched xylans, being beechwood xylan the preferred substrate. The optimum pH and temperature of the purified enzyme were 6.5 and 50 °C, respectively. Catalytic constants were determined on beechwood xylan, on which Xyn11E showed a Km of 12.98 mg/ml and a Vmax of 3,023 U/mg. The enzyme hydrolyzed long xylooligosaccharides, while oligomers shorter than xylotetraose were not degraded. Products released from glucuronoxylans were shorter than those liberated from cereal arabinoxylans. The xylanase was dependent on P. barcinonensis BP-23 LppX for its expression in an active form. Coexpression of Xyn11E with E. coli chaperones could not replace the need of LppX, which seems to act as a specific chaperone for Xyn11E correct folding. Activity of the enzyme on bleached pulps was evaluated. Xyn11E liberated reducing sugars from ECF and TCF pulps from eucalyptus, sisal, and flax, which makes it a good candidate for the enzymatic-assisted production of high-cellulose-content pulps from paper-grade pulps.


Assuntos
Paenibacillus/enzimologia , Xilosidases/genética , Xilosidases/metabolismo , Clonagem Molecular , DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Concentração de Íons de Hidrogênio , Ponto Isoelétrico , Cinética , Dados de Sequência Molecular , Peso Molecular , Paenibacillus/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Análise de Sequência de DNA , Especificidade por Substrato , Temperatura , Xilosidases/química , Xilosidases/isolamento & purificação
18.
Appl Microbiol Biotechnol ; 98(10): 4479-90, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24407449

RESUMO

Lipases and esterases are important biocatalysts for synthetic organic fine chemistry. An esterase from Bacillus sp. BP-7 (EstBP7) bears in its amino acid sequence a rare GGG(A)X oxyanion hole motif, where an uncommon threonine (T) is found at the third position. Detection of this pattern motivated evaluation of the ability of EstBP7 for conversion of tertiary alcohols. The enzyme was engineered in order to optimize its performance to provide important chiral building blocks: five variants with mutations in the oxyanion hole motif were created to investigate the influence on activity and enantioselectivity in the kinetic resolution of eight acetates of tertiary alcohols. Wild-type enzyme converted all esters of tertiary alcohols assayed with low enantioselectivity, whereas some of the mutants displayed significantly increased E-values. One of the mutants (EstBP7-AGA; Mut 5) showed an E >100 towards a complex tertiary alcohol acetate (2-(4-pyridyl)but-3-yn-2-yl acetate) at low reaction temperature (4 °C). Therefore, the catalytic toolbox was expanded for biocatalysis of optically pure tertiary alcohols valuable for the pharmaceutical industry.


Assuntos
Bacillus/enzimologia , Esterases/metabolismo , Ésteres/metabolismo , terc-Butil Álcool/metabolismo , Motivos de Aminoácidos , Substituição de Aminoácidos , Bacillus/genética , Temperatura Baixa , Esterases/genética , Engenharia de Proteínas , Especificidade por Substrato
19.
Appl Microbiol Biotechnol ; 97(19): 8559-68, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23334513

RESUMO

Rhodococci are highly adaptable bacteria, capable to degrade or transform a large number of organic compounds, including recalcitrant or toxic products. However, little information is available on the lipases of the genus Rhodococcus, except for LipR, the first lipase isolated and described from strain Rhodococcus CR-53. Taking into consideration the interest raised by the enzymes produced by actinomycetes, a search for new putative lipases was performed in strain Rhodococcus CR-53. We describe here the isolation, cloning, and characterization of intracellular esterase Est4, a mesophilic enzyme showing preference for short-chain-length acyl groups, without interfacial activation. Est4 displays moderate thermal and pH stability and low tolerance to most tested ions, being inhibited by detergents like sodium dodecyl sulfate and Triton X-100®. Nevertheless, the enzyme shows good long-term stability when stored at 4-20 °C and neutral pH. Amino acid sequence analysis of Est4 revealed a protein of 313 amino acids without a signal peptide, bearing most of the conserved blocks that define bacterial lipase family IV, thus being assigned to this family. Detection of a GGG(A)X oxyanion hole in the enzyme motivated the evaluation of Est4 ability to convert tertiary alcohol esters. The newly discovered esterase Est4 from Rhodococcus CR-53 successfully hydrolyzed the tertiary alcohol esters linalyl acetate, terpinyl acetate, and 1,1,1-trifluoro-2-phenylbut-3-yn-2-yl acetate.


Assuntos
Álcoois/metabolismo , Esterases/metabolismo , Rhodococcus/enzimologia , Sequência de Aminoácidos , Clonagem Molecular , DNA Bacteriano/química , DNA Bacteriano/genética , Inibidores Enzimáticos/metabolismo , Estabilidade Enzimática , Esterases/química , Esterases/genética , Esterases/isolamento & purificação , Concentração de Íons de Hidrogênio , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Rhodococcus/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Especificidade por Substrato , Temperatura , terc-Butil Álcool
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