ABSTRACT
Haemophilus influenzae type b, an encapsulated bacterium, causes meningitis in infants worldwide. The capsular polysaccharide conjugated to a carrier protein is effective in the prevention of such infections. The traditional purification process of polysaccharide from bacterial cultures for vaccine production is based on several selective precipitations with solvents such as: ethanol, phenol, and cationic detergents. The separations of solid and liquid phases are based on continuous centrifugation in explosion proof installations. The lipopolysaccharides are separated by ultracentrifugation. A simple and efficient method that can easily be scaled-up was developed for purification of polysaccharides. The ethanol precipitation was reduced to only two steps. The phenol treatment was substituted by ultrafiltration and enzymatic digestion. Lipopolysaccharide was removed by ultrafiltration together with addition of detergent and chelating agent.
Subject(s)
Centrifugation/methods , Haemophilus influenzae type b/chemistry , Polysaccharides, Bacterial/isolation & purification , Ultrafiltration/methods , Bioreactors/microbiology , Chemical Precipitation , Ethanol/chemistry , Haemophilus influenzae type b/metabolism , Lipopolysaccharides/chemistry , Lipopolysaccharides/isolation & purification , Polysaccharides, Bacterial/chemistryABSTRACT
Haemophilus inXuenzae type b, an encapsulatedbacterium, causes meningitis in infants worldwide. The capsularpolysaccharide conjugated to a carrier protein is eVectivein the prevention of such infections. The traditional puriWcationprocess of polysaccharide from bacterial cultures for vaccineproduction is based on several selective precipitationswith solvents such as: ethanol, phenol, and cationic detergents.The separations of solid and liquid phases are based oncontinuous centrifugation in explosion proof installations. Thelipopolysaccharides are separated by ultracentrifugation. Asimple and eYcient method that can easily be scaled-up wasdeveloped for puriWcation of polysaccharides. The ethanolprecipitation was reduced to only two steps. The phenol treatmentwas substituted by ultraWltration and enzymatic digestion.Lipopolysaccharide was removed by ultraWltrationtogether with addition of detergent and chelating agent.
Subject(s)
Male , Female , Humans , Child , Haemophilus influenzae type b/immunology , Meningitis, Haemophilus , Meningococcal VaccinesABSTRACT
Objetivos: Estabelecer curva de normalidade da freqüência cardíaca fetal (FCF) entre a 10ª e a 14ª semana de gestaçäo. Métodos: a FCF foi avaliada em 1078 fetos entre 10 e 14 semanas de gestaçäo. Para uma melhor correlaçäo da FCF com a idade gestacional, os fetos foram divididos em quatro grupos de acordo com a idade gestacional: Grupo I (10 semanas), Grupo II (11 semanas), Grupo III (12 semanas) e Grupo IV (13 semanas). Por meio de corte sagital, o coraçäo fetal foi visualizado e o registro da FCF foi realizado usando Modo-B e Modo-M em tempo real. Calculou-se a FCF média eletronicamente por meio da colocaçäo dos cálipers que registravam 3 ciclos consecutivos. Resultados: a FCF variou entre 136 e 178 bpm entre os 1078 fetos estudados. Construiu-se uma curva de normalidade estabelecendo-se a mediana e os percentis 5 e 95 da FCF para cada grupo. No Grupo I a FCF variou de 158 a 184 bpm; no Grupo II, de 155 a 175 bpm; no Grupo III, de 152 a 172 bpm; no Grupo IV, de 149 a 168 bpm. Houve uma diminuiçäo progressiva e significativa da FCF com o avanço da idade gestacional durante o período estudado. Conclusöes: a avaliaçäo da FCF no primeiro trimestre de gestaçäo é um procedimento simples e que deve ser analisado näo só na sua forma qualitativa (batimentos cardíacos fetais rítmicos) mas também na sua forma quantitativa, já que trabalhos publicados mostram a sua relaçäo com o prognóstico fetal.
