Eficacia bactericida in vivo del farnesol sobre implantes de Ti6Al4V / In vivo bactericidal efficacy of farnesol on Ti6Al4V implants

Objetivo. Evaluar in vivo la actividad bactericida antiestafilocócica del farnesol sobre superficies de Ti6Al4V. Material y métodos. Se desarrolló un modelo experimental de infecciones en biomateriales inoculando Staphylococcus aureus ATCC 29213 en los fémures de 15 ratas wistar. Seguidamente se insertó una aguja de Ti6Al4V impregnada con farnesol 30 mM en el fémur estudio y una aguja control en el fémur control. Para valorar la eficacia bactericida se compararon las medianas de unidades formadoras de colonias recuperadas después de la inoculación en el grupo estudio y en el grupo control, para diferentes tiempos de eutanasia y tamaño de inóculos. Resultados. La mediana expresada en Log10 de los recuentos de UFC obtenidos en agujas de titanio con farnesol fue de 4,26 y en agujas sin farnesol, controles, fue de 4,86. Esta diferencia, al aplicar la prueba de t de Student para muestras relacionadas, resultó ser estadísticamente significativa (p = 0,001). La reducción mediana obtenida en las agujas con farnesol respecto a las agujas control fue del 74%. Conclusiones. El tratamiento con farnesol de agujas de Ti6Al4V, a una concentración de 30 mM, parece disminuir la tasa de colonización por Staphylococcus aureus en dichas agujas (AU)

Objective. To evaluate the in vivo anti-staphylococcal bactericidal activity of farnesol on Ti6Al4V surfaces. Material and methods. An experimental model of infection in biomaterials was developed by inoculation of Staphylococcus aureus ATCC 29213 into the canal of both femurs of 15 Wistar rats. A Ti6Al4V pin impregnated with 30 mM of farnesol was inserted into study femur, and a Ti6Al4V control was inserted into the control femur. To evaluate the bactericidal efficacy, a comparison was made between the median of the colony forming units recovered after inoculation in the study group and the control group for different times of euthanasia and inoculum size. Results. The median expressed as Log10 CFU counts obtained with farnesol titanium pin was 4.26, and in control group, it was 4.86, which was statistically significant (P=.001) on applying the Student t test for related samples. The median reduction obtained in farnesol pins relative to the control was 74%. Conclusions. Treatment with farnesol 30 mM on Ti6Al4V pins appears to decrease the rate of colonisation by Staphylococcus aureus (AU)

Comparison of the Use of Washburn's Equation in the Distance-Time and Weight-Time Imbibition Techniques.

Two experimental methods are usually employed to study liquid penetration in porous media. One of them is based on the measure of the height of the advance liquid front vs time, and the other one is based on the measure of the weight gained by the porous system due to the liquid penetration vs time. Generally, the experimental data obtained from these techniques are analyzed through Washburn's equation. However, depending on which of them is selected, different conditions, coming from the experimental method, are needed to be taken into account in order to get the correct application of Washburn's equation to the experimental data. Although these conditions are different for each method, we prove in this paper that only if these conditions are considered both techniques are equivalent to analyze imbibition experiments using Washburn's equation. Copyright 2001 Academic Press.

On the Use of Washburn's Equation in the Analysis of Weight-Time Measurements Obtained from Imbibition Experiments.

A careful analysis of the experimental results from imbibition experiments, expressed as the increased weight of a porous layer once it was in contact with a liquid, vs time, has been done on the basis of Washburn's equation, which is usually the main tool for that analysis. It has been found that the experimental results reflect other physical phenomena more than imbibition, among them the effect of the initial contact between plate and liquid and the evaporation of liquid from the wetted porous layer. The unavoidable disturbance introduced by the first of these phenomena leads to the need for rescaling of the experimental data. Once this is done, Washburn's equation has to be applied accordingly to the new reference system chosen. Also, it has been shown that if evaporation is present, experimental data deviate from Washburn's predictions. This effect disappears if the porous layer is covered. Copyright 1999 Academic Press.

Distance-Time Measurements in Capillary Penetration: Choice of the Coordinate System.

Washburn's equation is a useful tool for studying the penetration of liquids in porous media because it predicts a relationship between the distance penetrated by the liquid in the porous media, x, and the time spent in this process, t. Despite its extended applicability, some problems in the interpretation of the results obtained arise from its use in the linearized form of x2 vs t. In this paper a careful mathematical analysis of Washburn's equation shows that most of the discordance found from its application comes from inadequate use of Washburn's equation. To confirm this assessment, the penetration of different liquids in plates used in thin-layer chromatography was investigated. From that study it has been proved that the alien behavior appearing when Washburn's equation is used in a linearized form disappears when it is used in its polynomial expression. Copyright 1999 Academic Press.