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Id: biblio-1022928
Autor: Xu, Qingyang; Bai, Fang; Chen, Ning; Bai, Gang.
Título: Removing the by-products acetic acid and NH4 + from the L-tryptophan broth by vacuum thin film evaporation during L-tryptophan production
Fonte: Electron. j. biotechnol;33:46-51, May. 2018. ilus, graf.
Idioma: en.
Projeto: Key Technologies R & D Program of Tianjin.
Resumo: Background: During L-tryptophan production by Escherichia coli, the by-products, acetic acid and NH4 +, accumulate in the fermentation broth, resulting in inhibited cell growth and activity and decreased L-tryptophan production. To improve the L-tryptophan yield and glucose conversion rate, acetic acid and NH4 + were removed under low-temperature vacuum conditions by vacuum scraper concentrator evaporation; the fermentation broth after evaporation was pressed into another fermenter to continue fermentation. To increase the volatilisation rate of acetic acid and NH4 + and reduce damage to bacteria during evaporation, different vacuum evaporation conditions were studied. Results: The optimum operating conditions were as follows: vacuum degree, 720 mm Hg; concentration ratio, 10%; temperature, 60°C; and feeding rate, 300 mL/min. The biomass yield of the control fermentation (CF) and fermentation by vacuum evaporation (VEF) broths was 55.1 g/L and 58.3 g/L at 38 h, respectively, (an increase of 5.8%); the living biomass yield increased from 8.9 (CF) to 10.2 pF (VEF; an increase of 14.6%). L-tryptophan production increased from 50.2 g/L (CF) to 60.2 g/L (VEF) (an increase of 19.9%), and glucose conversion increased from 18.2% (CF) to 19.5% (VEF; an increase of 7.1%). The acetic acid concentrations were 2.74 g/L and 6.70 g/L, and the NH4 + concentrations were 85.3 mmol/L and 130.9 mmol/L in VEF and CF broths, respectively. Conclusions: The acetic acid and NH4 + in the fermentation broth were quickly removed using the vacuum scraper concentrator, which reduced bacterial inhibition, enhanced bacterial activity, and improved the production of L-tryptophan and glucose conversion rate.
Descritores: Triptofano/biossíntese
Ácido Acético/metabolismo
Aminoácidos/metabolismo
-Vácuo
Resíduos
Evaporação
Escherichia coli
Fermentação
Responsável: CL1.1 - Biblioteca Central


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Id: biblio-1159954
Autor: Cohen, Alberto L; Monesiglio, Juan C.
Título: Aminoácidos libres en plasma: Valores normales en pediatría / Free amino acids in plasma: Normal values in pediatrics
Fonte: Arch. argent. pediatr;69(7):281-287, 1971 Sep. tab.
Idioma: es.
Resumo: Se dan las concentraciones de aminoácidos libres en plasma de niños normales, de edad comprendida entre el nacimiento (cordón umbilical) y los 11 años, determinados por cromatografía de intercambio iónico según el procedimiento de Spackman, Steina y Moore. Se expresan los resultados en miligramos/100 mililitros, micromoles/litro y micromoles 100 micromoles.
Descritores: Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico
Aminoácidos/sangue
-Cromatografia
Métodos
Limites: Humanos
Masculino
Feminino
Gravidez
Recém-Nascido
Lactente
Pré-Escolar
Criança
Responsável: AR94.1 - Centro de Información Pediatrica


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Id: biblio-1178840
Autor: Mamani Mayta, Deysi Danitza; Gutiérrez Durán, María Del Pilar; Serrudo Juárez, Jorge Armando; Gonzales Dávalos, Eduardo.
Título: Parámetros de calidad de harinas de Amaranthus caudatus Linnaeus (amaranto), Chenopodium quinoa Willd (quinua), Chenopodium pallidicaule Aellen (kañahua), Lupinus mutabilis Sweet (tarwi) / Quality parameters of flour of Amaranthus caudatus Linnaeus (amaranth), Chenopodium quinoa Willd (quinoa), Chenopodium pallidicaule Aellen (kañahua), Lupinus mutabilis Sweet (tarwi)
Fonte: Con-ciencia (La Paz);5(1):27-38, jun. 2017. ilus., tab..
Idioma: es.
Resumo: Las especies vegetales Amaranthus caudatus Linnaeus (amaranto), Chenopodium quinoa Willd (quinua), Lupinus mutabilis Sweet (tarwi), Chenopodium pallidicaule Aellen (kañahua), llamados también granos andinos, son desde hace mucho tiempo la base de alimentación de muchas familias en nuestro país, estos granos son reconocidos por su alto valor nutricional. En la actualidad varias empresas de nuestra región comercializan estos granos en su forma procesada. Este trabajo tuvo como finalidad establecer los parámetros de calidad e identificación de las harinas de amaranto, quinua, kañahua y tarwi provenientes de los municipios de Ancoraimes, Tomina, Huancané y Peñas, para ello se realizó el análisis micrográfico encontrándose almidón, aleurona y grasa como principales elementos. El análisis fisicoquímico realizado reportó un contenido de humedad en quinua de 6,03%, cenizas totales 2,52% y 3,8 ml como índice de hinchamiento. En amaranto un contenido de humedad de 5,76%, cenizas totales 2,86% y 6,8 ml como índice de hinchamiento. Tarwi reportó un contenido de humedad de 6,69%, cenizas totales 3,53%, y 3,6 ml como de índice de hinchamiento. Kañahua reportó un contenido de humedad de 5,82%, cenizas totales 3,53% y 4,75ml como índice de hinchamiento. El análisis químico cualitativo en los granos muestra la presencia mayoritaria de flavonoides, aminoácidos, antocianidinas, taninos.

The plant species Amaranthus caudatus Linnaeus (amaranth), Chenopodium quinoa Willd (quinoa), Lupinus mutabilis Sweet (tarwi), Chenopodium pallidicaule Aellen (kañahua), also called Andean grains, have long been the food base of many families in our Country, these grains are recognized for their high nutritional value. At present several companies of our region commercialize these grains in its processed form. The aim of this work was to establish the parameters of quality and identification of the amaranth, quinoa, kañahua and tarwi flours from the municipalities of Ancoraimes, Tomina, Huancané and Peñas. For this purpose, the micrographic analysis was performed with starch, aleurone and fat as main elements. The physicochemical analysis carried out reported a moisture content in quinoa of 6.03%, total ash 2.52% and 3.8 ml as swelling index. In amaranth a moisture content of 5.76%, total ash 2.86% and 6.8 ml as swelling index. Tarwi reported a moisture content of 6.69%, total ash 3.53%, and 3.6 ml as the index of swelling. Kañahua reported a moisture content of 5.82%, total ash 3.53% and 4.75ml as swelling index. The qualitative chemical analysis in the grains shows the majority presence of flavonoids, amino acids, anthocyanidins, tannins.
Descritores: Chenopodium quinoa
Lupinus
Dieta
Alimentos
Valor Nutritivo
-Plantas
Flavonoides
Amaranthus
Farinha
Aminoácidos
Responsável: BO138.1 - Biblioteca Central


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Id: biblio-1178915
Autor: Segurondo Loza, Romina; Pantoja, María Rosa; Rocha, Eliana.
Título: Determinación de la genuinidad en jugos de naranja comercializados en los supermercados de la ciudad de La Paz / Determination of the genuineness in juices of orange marketed in supermarkets from the city of La Paz
Fonte: Con-ciencia (La Paz);1(1):105-112, oct. 2013. ilus..
Idioma: es.
Resumo: La producción mundial de jugos cítricos concentrados se estima en 2,6 millones de toneladas. El jugo de naranja representa el 88% del total. El mercado es liderizado por Brasil con el 50% del volumen elaborado, seguido por EEUU con el 40%. En Bolivia el mercado de frutas se encuentra en continuo crecimiento, tanto para importación como para consumo interno. Actualmente se comercializan bebidas a base de jugo de frutas tanto de importación como de fabricación nacional, las mismas que son sometidas a control por los Organismos Oficiales Ministerio de Salud y Deportes, y el Servicio Nacional de Sanidad Agropecuaria e Inocuidad Alimentaria - SENASAG bajo la Normativa Nacional e Internacional reconocida como es la Norma Boliviana y el Codex Alimentarius, al igual que todos los productos alimenticios para garantizar su calidad e inocuidad. El presente trabajo pretende determinar la genuinidad de los jugos comercializados en nuestro medio para lo cual el método por espectrofotometría fue el que nos permitió cuantificar la concentración de prolina como aminoácido predominante presente en la naranja. Actualmente el análisis laboratorial se basa principalmente en las determinaciones de parámetros fisicoquímicos que necesitan ser complementados con otros métodos analíticos como: la Cuantificación de Prolina por Espectrofotometría y el Indice de Formol propuestos en éste trabajo, capaces de determinar la genuinidad de jugos de naranja presentes en el comercio de la ciudad de La Paz, y así colaborar con los Organismos de Control para cumplir a cabalidad con la responsabilidad de garantizar que los productos consumidos por nuestra población cumplen con lo declarado en sus etiquetas. El estudio reveló que todas las muestras analizadas cumplen con lo establecido en los parámetros fisicoquímicos, mientras que en los parámetros de genuinidad sugeridos en el presente trabajo, el 62% cumple con los límites de referencia del índice de formol y sólo un 44% con los límites de prolina.

World production of citrus juice concentrates, is estimated at 2.6 million tonnes. Orange juice accounts for 88% of the total. The market is led by Brazil with 50% of the volume produced, followed by U.S. with 40%. In Bolivia the fruit market is still growing, both for imports and for domestic consumption Currently marketed drinks based on fruit juice both import and domestic manufacture, they are subject to control by government agencies Ministry of Health and Sports and the National Service of Agricultural Health and Food Safety - SENASAG under national and international standards is recognized as the Standard Bolivian and the Codex Alimentarius, like all food products to ensure quality and safety. This paper aims to determine the genuine from the juices marketed in our area for which the method was spectrophotometrically which allowed us to quantify the concentration of the amino acid praline as a dominant presence in the orange Currently, the laboratory analysis is mainly based on the determinations of physical and chemical parameters that need to be complemented by other analytical methods such as: Quantifying Proline by spectrophotometry, and Formol Index proposed in his work, able to determine the genuine orange juice in the trade of the city of La Paz, and collaborate with the supervisory bodies to fulfill the responsibility to ensure that the products consumed by our population satisfied with what was stated on their labels. The study revealed that all the samples tested complied with the parameters established physicochemical while in the parameters of genuine suggested in the present study, 62.5% comply with the limits of the reference rate of formol and only 43, 75% with the limits of proline.
Descritores: Espectrofotometria
Prolina
-Gestão da Qualidade
Sucos
Parâmetros de Referência
Sucos de Frutas e Vegetais
Formaldeído
Aminoácidos
Tipo de Publ: Artigo Clássico
Responsável: BO138.1 - Biblioteca Central


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Id: biblio-1138617
Autor: López, Lizbeth; Vela, Marcela; Ibarra, Isabel; Díaz, Luisa; Belmont, Leticia; Guillén, Sara.
Título: Positive improvement in palatability of metabolic formula with the use of miraculin protein in patients with inborn errors of metabolism and healthy adults / Cambio positivo en la palatabilidad de la fórmula metabólica con el uso de la proteína miraculina en pacientes con errores innatos del metabolismo y adultos sanos
Fonte: Rev. chil. nutr;47(5):801-807, set. 2020. tab, graf.
Idioma: en.
Resumo: ABSTRACT As palatability of medical formulas has been documented as unpleasant, new options are required to improve acceptance and adherence in people with inborn errors of metabolism (IEM). Miracle fruit (Synsepalum dulcificum) has a glycoprotein named miraculin that transforms a sour, bitter taste such as the one found in metabolic formula, into a sweet perception. The objective of this work is to analyze the response in the taste perception of metabolic formula with the use of the miraculin tablets in patients with IEM and healthy adults. To test this hypothesis a prospective, longitudinal, quasi-experimental, analytical study was performed. Patients with IEM and healthy adults were recruited. All participants assessed 3 different liquids (lemon, apple cider vinegar and metabolic formula) before and after the administration of miraculin tablets and completed a questionnaire. The sensory responses were evaluated using hedonic scales, analyzed with nonparametric tests for paired data. Seven patients with IEM and 14 healthy subjects were included. After miraculin intake 57% of patients (Z ≤ -1.89 p= 0.059) and healthy adults (Z≤ -2.31 p= 0.021) had a positive change in their taste perception. The absolute frequency of patients who did not like the metabolic formula decreased from 4 to 1, and in patients who liked it or loved, it increased from 0 to 2 and from 0 to 1 respectively; the frequency of patients who perceived the metabolic formula as indifferent or hated it, did not change. Response in taste perception had a positive change of 57% in both groups. The use of miraculin tablets may improve palatability of metabolic formula.

RESUMEN La palatabilidad de las fórmulas médicas se ha reportado como desagradable, se requieren nuevas opciones para mejorar la aceptación en personas con errores innatos del metabolismo (EIM). La fruta milagrosa (Synsepalum dulcificum) contiene una glucoproteína llamada miraculina que transforma el sabor agrio y amargo en dulce. El objetivo fue analizar la respuesta en la percepción del sabor de la fórmula metabólica con el uso de las tabletas de miraculina en pacientes con EIM y adultos sanos. Se realizó un estudio analítico prospectivo, longitudinal, cuasi-experimental. Los participantes evaluaron la percepción de 3 líquidos (limón, vinagre de manzana y fórmula metabólica) antes y después de la administración de tabletas de miraculina y completaron un cuestionario. Las respuestas sensoriales se evaluaron mediante escalas hedónicas, analizadas con pruebas no paramétricas para datos pareados. Se incluyeron 7 pacientes con EIM y 14 adultos sanos. Después de la miraculina el 57% de los pacientes (Z ≤ -1,89 p= 0,059) y adultos sanos (Z≤ -2,31 p= 0,021) tuvieron un cambio positivo en su percepción del sabor. La frecuencia absoluta de pacientes a los que no les gustó la fórmula disminuyó de 4 a 1, y en quienes les gustó o les encantó, aumentó de 0 a 2 y de 0 a 1 respectivamente; la frecuencia de los pacientes que percibieron la fórmula como indiferente u odiada, no cambió. La respuesta en la percepción del sabor cambió positivamente en el 57% en ambos grupos. El uso de miraculina puede mejorar la palatabilidad de la fórmula metabólica.
Descritores: Biotransformação
Synsepalum
Percepção Gustatória
-Frutas
Aminoácidos
Erros Inatos do Metabolismo
Limites: Adolescente
Adulto
Tipo de Publ: Artigo Clássico
Responsável: CL334.1 - Biblioteca UBO


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Id: biblio-1132169
Autor: Rosa-Garzon, Nathalia Gonsales da; Siqueira, Ana Claudia Rodrigues de; Hirano, Viviane Naomi; Rodrigues, André; Pessela, Benevides Costa; Cabral, Hamilton.
Título: Amino Acid Supplementation Improves the Production of Extracellular Peptidases by Aspergillus Section Flavi and their Ionic Immobilization
Fonte: Braz. arch. biol. technol;63:e20190127, 2020. graf.
Idioma: en.
Projeto: Fundação de Amparo à Pesquisa do Estado de São Paulo; . Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.
Resumo: Abstract Bioprocess studies have been highlighted due to the importance of physiological processes and industrial applications of enzymes. The potential of peptidase production from Aspergillus section Flavi using different amino acids as a supplemental nitrogen source was investigated. A production profile revealed that amino acids had positive effects on peptidase production when compared to the control without amino acids. Optimal production (100 U/mL) was obtained with Arginine amino acid in 96 h of fermentation. Extracellular peptidase from Aspergillus section Flavi was identified in submerged bioprocesses by in situ activity. Biochemical studies revealed that the maximum activities of the enzyme extract were obtained at pH 6.5 and a temperature of 55°C. The inhibition by EDTA and PMSF suggests the presence of more than one peptidase while the Ni2+ and Cu2+ had a negative influence on the enzyme activity. When the crude extract was reversibly immobilized on ionic supports, DEAE-Agarose and MANAE-Agarose the derivative showed different profiles of thermal and pH stabilities. Hence, this study revealed the basic properties and biochemical characteristics that allowed the production improvement of this class of enzyme. Moreover, with known properties stabilization and immobilization process is required to further explore its biotechnological capacities.
Descritores: Peptídeo Hidrolases/biossíntese
Aspergillus/enzimologia
Aminoácidos/administração & dosagem
-Arginina
Sefarose
Inibidores Enzimáticos
Responsável: BR1.1 - BIREME


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Id: biblio-950560
Autor: El-Haggar, Sahar Mohamed; Mostafa, Tarek Mohamed; Allah, Horeya Mohamed Sad; Akef, Ghada Hassan.
Título: Levetiracetam and lamotrigine effects as mono- and polytherapy on bone mineral density in epileptic patients / Efeitos do levetiracetam e lamotrigina, em mono e politerapia, na densidade mineral óssea de pacientes epilépticos
Fonte: Arq. neuropsiquiatr;76(7):452-458, July 2018. tab.
Idioma: en.
Resumo: ABSTRACT The purpose of this study was to determine the effect of lamotrigine (LTG) and levetiracetam (LEV) as mono- and polytherapy on biochemical markers of bone turnover and bone mineral density in Egyptian adult patients with epilepsy. Methods Forty-eight patients were divided into four groups: two received monotherapy of either LTG or LEV, and the other two groups received polytherapy comprising (valproate [VPA] + LTG or VPA + LEV). Thirty matched healthy participants were included in the study. Participants completed a nutritional and physical activity questionnaire. Biochemical markers of bone and mineral metabolism and bone mineral density of the lumbar spine were measured at baseline and at six months. Results In the LEV monotherapy group, the bone formation markers showed a significant decrease in serum alkaline phosphatase and serum osteocalcin levels while the bone resorption marker showed a significant increase in urinary deoxypyridinoline levels. After six months of treatment, bone mineral density showed a significant decrease in all treated groups, while among monotherapy groups, this significant decrease was more prevalent in the LEV monotherapy group compared with the LTG monotherapy group. Furthermore, there was significant negative correlation between urinary deoxypyridinoline levels and bone mineral density in the LEV monotherapy group. Conclusion Using new generation antiepileptics, LEV monotherapies and polytherapy showed harmful effects on bone but LTG did not.

RESUMO O objetivo deste estudo foi determinar o efeito da lamotrigina (LTG) e levetiracetam (LEV) como mono e politerapia em marcadores bioquímicos de remodelação óssea e densidade mineral óssea em pacientes adultos egípcios com epilepsia. Métodos Quarenta e oito pacientes foram divididos em quatro grupos: dois grupos receberam monoterapia de LTG ou LEV e os outros dois grupos receberam politerapia (valproato [VPA] + LTG ou VPA + LEV). Trinta participantes saudáveis controle foram incluídos no estudo. Os participantes preencheram um questionário nutricional e de atividade física. Marcadores bioquímicos do metabolismo ósseo e mineral e densidade mineral óssea da coluna lombar foram medidos no início e aos seis meses. Resultados No grupo de monoterapia LEV, os marcadores de formação óssea mostraram uma diminuição significativa nos níveis séricos de fosfatase alcalina e osteocalcina sérica, enquanto o marcador de reabsorção óssea mostrou um aumento significativo nos níveis de desoxipiridinolina urinária. Após seis meses de tratamento, a densidade mineral óssea mostrou uma diminuição significativa em todos os grupos tratados, enquanto entre os grupos de monoterapia, esta diminuição significativa foi mais prevalente no grupo de monoterapia LEV em comparação com o grupo de monoterapia LTG. Além disso, houve correlação negativa significativa entre os níveis de desoxipiridinolina urinária e densidade mineral óssea no grupo de monoterapia LEV. Conclusão Utilizando antiepilépticos de nova geração, as monoterapias LEV e a politerapia mostraram efeitos prejudiciais no osso, mas a LTG não.
Descritores: Piracetam/análogos & derivados
Triazinas/efeitos adversos
Densidade Óssea/efeitos dos fármacos
Ácido Valproico/efeitos adversos
Remodelação Óssea/efeitos dos fármacos
Anticonvulsivantes/efeitos adversos
-Piracetam/administração & dosagem
Piracetam/efeitos adversos
Triazinas/administração & dosagem
Biomarcadores/urina
Biomarcadores/sangue
Estudos de Casos e Controles
Osteocalcina/sangue
Ácido Valproico/administração & dosagem
Quimioterapia Combinada
Epilepsia/tratamento farmacológico
Lamotrigina
Levetiracetam
Aminoácidos/urina
Anticonvulsivantes/administração & dosagem
Limites: Humanos
Masculino
Feminino
Adolescente
Adulto
Adulto Jovem
Responsável: BR1.1 - BIREME


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Id: biblio-1178614
Autor: Cavero Olguin, Victor Hugo.
Título: Dióxido de cloro, los milagros no existen / Chlorine dioxide, miricles do not exist
Fonte: Con-ciencia (La Paz);8(1):79-97, 20200400. ilus..
Idioma: es.
Resumo: OBJETIVOS: contribuir con una revisión bibliográfica acerca de la acción del dióxido de cloro sobre ciertos microorganismos y biomoléculas. Hacer una revisión de sus usos, toxicidad, reactividad química y bioquímica además de los estudios llevados adelante en modelos animales. Entender cuál es el alcance de los estudios en modelos animales y relacionarlos con la posibilidad de realizar estudios en humanos. METODOLOGÍA: se realizó una revisión exhaustiva sobre el dióxido de cloro. Su uso como antiséptico, toxicidad, estructura molecular, generación de oxígeno molecular, reactividad con biomoléculas y experimentos en modelos animales para entender cuál es el estado del arte de las investigaciones sobre esta molécula. Todas las búsquedas fueron realizadas en bases de datos de artículos científicos así como también por intercambio de información con profesionales entendidos en el tema y curiosidades del colectivo popular. RESULTADOS: la estructura y reactividad molecular del dióxido de cloro determinan una reactividad alta con ciertos aminoácidos y proteínas, explicando así su actividad biológica inhibitoria. Varios estudios demostraron esta actividad inhibitoria frente a diferentes microorganismos, incluyendo los virus. Tales datos y un ensayo clínico en humanos determinaron una baja toxicidad a bajas concentraciones. Sin embargo, pese a tales evidencias, la falta de más estudios clínicos en situaciones controladas inviabiliza la posibilidad de extrapolar los datos al ser humano para mitigar enfermedades infecciosas como el Covid-19. CONCLUSIONES: la reactividad del dióxido de cloro queda clara y su acción sobre las proteínas explica su efectiva acción contra microorganismos como los virus. Su baja toxicidad en estudios llevados adelante en modelos animales abre la posibilidad de más estudios clínicos. Extrapolar los datos que se tienen hasta ahora al ser humano no es correcto.

OBJECTIVES: to contribute with a bibliographic review about the action of chlorine dioxide on certain microorganisms and biomolecules. To review its uses, toxicity, chemical and biochemical reactivity besides studies carried out in animal models. To understand what the extent of the studies in animal models is and relate them with the possibility of carrying out studies in humans. METHODOLOGY: an exhaustive review has been done about chlorine dioxide. Its use as an antiseptic, toxicity, molecular structure, molecular oxygen generation, reactivity with biomolecules and experiments on animal models to understand at which state of the art the research on this molecule is. Every search was carried out in data bases of scientific papers as well as by information exchange with professionals of the field and certain curiosities of the popular collective. RESULTS: The structure and molecular reactivity of chlorine dioxide determines a high reactivity with certain aminoacids and proteins, therefore explaining its inhibitory biological activity. Several studies demonstrated this inhibitory activity against different microorganisms, including viruses. These data and a clinical assay in humans determined a low toxicity at low concentrations. Nonetheless, the lack of more human clinical studies in controlled situations prevents it from the possibility to extrapolate those data to human beings in order to mitigate infectious diseases like Covid-19. CONCLUSIONS: the reactivity of chlorine dioxide remains clarified and its action on proteins explains the effective action against microorganisms like viruses. Its low toxicity in studies carried out in animal models opens the possibility of more clinical studies. Extrapolate data obtained so far to human beings is not correct.
Descritores: Sistema Único de Saúde
Dióxido de Cloro
Aminoácidos
-Literatura de Revisão como Assunto
Infecções por Coronavirus
Toxicidade
Tipo de Publ: Revisão
Responsável: BO138.1 - Biblioteca Central


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Id: biblio-950858
Autor: Simm, Stefan; Einloft, Jens; Mirus, Oliver; Schleiff, Enrico.
Título: 50 years of amino acid hydrophobicity scales: revisiting the capacity for peptide classification
Fonte: Biol. Res;49:1-19, 2016. ilus, graf, tab.
Idioma: en.
Projeto: Deutsche Forschungsgemein.
Resumo: BACKGROUND: Physicochemical properties are frequently analyzed to characterize protein-sequences of known and unknown function. Especially the hydrophobicity of amino acids is often used for structural prediction or for the detection of membrane associated or embedded ß-sheets and α-helices. For this purpose many scales classifying amino acids according to their physicochemical properties have been defined over the past decades. In parallel, several hydrophobicity parameters have been defined for calculation of peptide properties. We analyzed the performance of separating sequence pools using 98 hydrophobicity scales and five different hydrophobicity parameters, namely the overall hydrophobicity, the hydrophobic moment for detection of the α-helical and ß-sheet membrane segments, the alternating hydrophobicity and the exact ß-strand score. RESULTS: Most of the scales are capable of discriminating between transmembrane α-helices and transmembrane ß-sheets, but assignment of peptides to pools of soluble peptides of different secondary structures is not achieved at the same quality. The separation capacity as measure of the discrimination between different structural elements is best by using the five different hydrophobicity parameters, but addition of the alternating hydrophobicity does not provide a large benefit. An in silico evolutionary approach shows that scales have limitation in separation capacity with a maximal threshold of 0.6 in general. We observed that scales derived from the evolutionary approach performed best in separating the different peptide pools when values for arginine and tyrosine were largely distinct from the value of glutamate. Finally, the separation of secondary structure pools via hydrophobicity can be supported by specific detectable patterns of four amino acids. CONCLUSION: It could be assumed that the quality of separation capacity of a certain scale depends on the spacing of the hydrophobicity value of certain amino acids. Irrespective of the wealth of hydrophobicity scales a scale separating all different kinds of secondary structures or between soluble and transmembrane peptides does not exist reflecting that properties other than hydrophobicity affect secondary structure formation as well. Nevertheless, application of hydrophobicity scales allows distinguishing between peptides with transmembrane α-helices and ß-sheets. Furthermore, the overall separation capacity score of 0.6 using different hydrophobicity parameters could be assisted by pattern search on the protein sequence level for specific peptides with a length of four amino acids.
Descritores: Interações Hidrofóbicas e Hidrofílicas
Aminoácidos/química
Proteínas de Membrana/química
-Valores de Referência
Fatores de Tempo
Pesos e Medidas
Algoritmos
Valor Preditivo dos Testes
Reprodutibilidade dos Testes
Sequência de Aminoácidos
Conformação Proteica em alfa-Hélice
Conformação Proteica em Folha beta
Aminoácidos/classificação
Responsável: CL1.1 - Biblioteca Central


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Id: lil-338285
Autor: Schiaveto, Emanuele C; Vidotto, Alessandra; Siqueira, Fátima A. M; Naoum, Paulo C; Fett-Conte, Agnes C; Bonini-Domingos, Claudia R.
Título: Hemoglobina Köln diagnosticada em programa de triagem neonatal em Säo José do Rio Preto, SP / Köln Hemoglobin found in Neonatal Screening Program in Säo José do Rio Preto, Säo Paulo, Brazil
Fonte: Rev. bras. hematol. hemoter;24(1):41-44, mar. 2002.
Idioma: pt.
Resumo: Alteraçöes genéticas em que a mutaçäo de aminoácidos nas globinas afeta a estrutura da molécula tornando-a instável säo classificadas como hemoglobinas instáveis. Devido à grande diversidade dos pontos de mutaçöes por substituiçöes e deleçöes de aminoácidos, as formas de instabilizaçäo se apresentam muito variadas. A hemoglobina Köln é a variante instável descrita com maior freqüência na literatura e a terceira descoberta no Brasil, as outras säo Hb Niterói e Hb Hasharon. Anemia moderada, icterícia e presença de urina escura caracterizam as manifestaçöes clínicas da Hb Köln. Em programa de triagem neonatal identificamos uma criança com suspeita de heterozigose para hemoglobina Köln, confirmada por procedimentos eletroforéticos e HPLC. Avaliaçöes por diferentes metodologias laboratoriais e estudo familiar auxiliam no diagnóstico precoce, possibilitando minimizar os sintomas decorrentes da hemoglobina anormal e a realizaçäo do aconselhamento genético e educacional destas alteraçöes hereditárias
Descritores: Hemoglobinas Anormais
-Urina
Hemoglobinas
Triagem Neonatal
Diagnóstico Precoce
Aminoácidos
Mutação
Tipo de Publ: Relatos de Casos
Responsável: BR408.1 - Biblioteca da Faculdade de Medicina - BFM



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