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...

Osteoporosis juvenil idiopatica / Idiopathic juvenile osteoporosis

Se describe un caso de osteoporosis juvenil idiopática, en un paciente masculino de 12 2/12 años de edad. La presentación clínica fue con un dolor en la cara posterior de tórax y la osteoporosis, un hallazgo radiológico. La evaluación de la función paratiroidéa, adrenal y gonadal por exploración física y exámenes paraclínicos fue normal. Se trató con analgésicos comunes y a 16 meses de seguimiento está asintomático. A pesar de que en las radiografías simples no existe mejoría en la densidad ósea, ésta es notoria en una tomografía axial computarizada practicada seis meses después de la primera. Consideramos que el diagnóstico de osteoporosis juvenil idiopática es por exclusión el tratamiento debe ser sintomático y la tomografía axial en nuestro caso demostró ser un método eficiente para evaluar cambios en la densidad ósea en un plazo corto