RESUMO
The supramolecular organisation of collagen adsorbed on polymer substrates was investigated as a function of properties of the substrates (chemical nature, roughness) and of characteristics of the collagen solution (concentration, state of aggregation) as well as details of the preparation procedure (adsorption time, drying rate). Elongated structures are formed at the interface by assembly of collagen molecular segments protruding into the solution. This is favoured by using a hydrophobic and smooth substrate, by increasing the adsorbed amount and by increasing the adsorption time, even beyond stages at which the adsorbed amount does no longer vary. Collagen adsorbed at low amount on hydrophobic substrates strongly reorganises into a net-like pattern if drying is performed at low rate. This is due to dewetting and collagen displacement by the water meniscus. Applications derived from the control of collagen organisation are presented. Nanostructured polymer surfaces were created starting from a collagen template. The attachment and the cytoskeletal organisation of mammalian cells (MCF-7/6) were also shown to depend on collagen organisation.
Assuntos
Materiais Revestidos Biocompatíveis/química , Colágeno Tipo I/química , Colágeno Tipo I/ultraestrutura , Poliestirenos/química , Adsorção , Cristalização/métodos , Dessecação , Dimerização , Substâncias Macromoleculares , Teste de Materiais , Membranas Artificiais , Ligação Proteica , Conformação Proteica , Propriedades de SuperfícieAssuntos
Streptococcus pneumoniae/classificação , Adolescente , Adulto , África , Fatores Etários , Animais , Portador Sadio , Criança , Pré-Escolar , Resistência Microbiana a Medicamentos , Feminino , Humanos , Lactente , Masculino , Meningite/microbiologia , Camundongos , Pessoa de Meia-Idade , Faringe/microbiologia , Sorotipagem , Fatores Sexuais , Fatores de TempoRESUMO
Pseudomonas aeruginosa and its corresponding bacteriophages were sought in oysters and mussels throughout 1973. Forty-eight percent of the oysters and 74% of the mussels examined during the last half of the year contained P. aeruginosa; serotype P3 was predominant. The percentage of oysters contaminated by bacteriophages active on P. aeruginosa increased throughout the year, from 0 to 4% between January and May to 69% in November. We were unable to establish a significant relationship between the presence of the bacterium and that of its specific bacteriophages in the shellfish.
Assuntos
Bacteriófagos/isolamento & purificação , Contaminação de Alimentos , Microbiologia de Alimentos , Pseudomonas aeruginosa/isolamento & purificação , Frutos do Mar , Bivalves , França , Ostreidae , Estações do Ano , SorotipagemRESUMO
The coenzyme Q system was examined on 55 strains of Gram negative aerobic or facultatively anaerobic rods. No bacteria contain Co-Q7 nor Co-Q10. Ubiquinone Q8 predominates in Flavobacterium and in Enterobacteriaceae; Q9 was the only homolog found in the Pseudomonas, and predominates in the Acinetobacter.
