The application of polymerized lipid vesicles as colorimetric biosensors for real-time detection of pathogens in drinking water

The inadequate treatments given to the served waste water which are disposal to the rivers and sea coast are the major sources of faecal Microorganisms and enteric bacterial pathogens. They are among the most serious effects of water pollution bringing risks on public health. None of the current methods for detection of pathogens offer real-time on site solutions, are capable of delivering a simple visual detection signal, or can be easily instrumented as an indicator of the presence of a pathogen in water. The use of lipid vesicles incorporating Polydiacetylenes (PDAs) for the development of biosensors for “real-time” detection of pathogens has become an alternative, due to its potential for simple colorimetric response against harmful environmental effectors. However, its actual application in the field has been complicated because lipid vesicles are unable to respond specifically to environmental changes. In this paper, we report several experimental trials leading to improved response in the detection of flagellated pathogens in drinking water. Chromatic biomimetic membranes of TRCDA/DMPC and TRCDA/DMPC/Tryptophan were used in agar and liquid media, which were challenged with different amounts of Escherichia coli and Salmonella typhimurium. In addition, the effect of some divalent cations on the interaction with vesicles TRCDA/DMPC was investigated. The results indicated an improvement in the response times, both visually and quantitatively, through the use of TRIS-EDTA and proper growing conditions for E. coli and Salmonella. With the application of both conditions, it was possible by incubation at 35ºC to promote bacterial growth, therefore avoiding a dramatic effect on the colour change over control samples which may invalidate the test. Our experiments indicated that the minimum bacterial concentration necessary to produce the transition from blue to red on the vesicles as biosensor approaches 10(8) CFU/ml within 4 hrs...

Infección cutánea por citomegalovirus en relación con el mecanismo patogénico del vitíligo generalizado de inicio reciente / Cytomegalovirus skin infection in relation with the initial pathogenic mechanism of early generalized Vitiligo

OBJETIVO: Demostrar la asociación de la infección cutánea por citomegalovirus en pacientes con vitíligo generalizado de inicio reciente. MATERIAL Y METODOS: Estudio de casos y controles realizado de marzo a diciembre del 2003. Se conformaron dos grupos para la investigación: un grupo de 30 pacientes con diagnóstico de vitíligo generalizado de inicio reciente y otro grupo control conformado por 30 sujetos sanos. De todos los pacientes se obtuvo muestras de piel a las que se realizó Reacción en Cadena de la Polimerasa para genoma de citomegalovirus y exámenes histopatológicos con tinciones hematoxilina-eosina. RESULTADOS: Se encontró que 23 pacientes con vitíligo (76.6 por ciento) fueron positivos para genoma de citomegalovirus en Reacción de Cadena de Polimerasa, mientras que sólo siete controles (23.3 por ciento) resultaron positivos. Se encontró diferencia estadística significativa para infección por citomegalovirus en los pacientes con vitíligo versus los controles con un OR = 10,7 (95 por ciento: IC 3,47 - 33,1) (p<0,001). El examen histopatológico para citomegalovirus fue negativo en el grupo de pacientes con vitíligo reciente y los controles. CONCLUSIONES: Existe asociación entre infeccion cutánea por citomegalovirus y vitíligo de inicio reciente en un grupo selecto de pacientes.