RESUMEN
We have developed a validated gas chromatography/mass spectrometry (GC/MS) method with two labelled cholesterol tracers, i.e. (2)H(4) ([2H4]-Chol) and (2)H(7) ([2H7]-Chol) enriched moieties, with a new way of calculating the abundance of labelled cholesterol in plasma without natural cholesterol interference. The isotopomers of the analytes could interfere during analysis. Elimination of these interferences can be performed by the blank or mathematical subtraction method. Validation was performed with the two interference elimination methods. For both methods, linearity was obtained in the range 5 x 10(-4) to 10(-2) mM for both labelled cholesterol moieties. In the same range, repeatability and reproducibility were less than 6.5% and 7.5% for [2H4]-Chol and [2H7]-Chol, respectively. Accuracy was about 100% and recoveries always included 100% for the two labelled cholesterols. We demonstrate that measurement of blank plasma is not necessary when using the validated abundance isotope calculation method. This saves time, reagent and samples. This calculation strategy can be extrapolated to comparable tracer approaches.
Asunto(s)
Artefactos , Análisis Químico de la Sangre/métodos , Colesterol/sangre , Cromatografía de Gases y Espectrometría de Masas/métodos , Humanos , Marcaje Isotópico/métodos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The antifungal effect of the essential oil from Satureja montana L., Lavandula angustifolia Mill., Lavandula hybrida Reverchon, Syzygium aromaticum (L.) Merril and Perry, Origanum vulgare L., Rosmarinus officinalis L. and six chemotypes of Thymus vulgaris L. on Candida albicans growth were studied. The most efficiency was obtained with the essential oil from Thymus vulgaris thymol chemotype (MIC 80% = 0.016 microL/mL and Kaff = 296 microL/mL). The presence in the culture medium of essential oil from Thymus vulgaris thymol chemotype (0.01, 0.1, 0.2, 0.3 microg/mL) and amphotericin B involved a decrease of the MIC 80% of amphotericin B. In contrast, the combination of amphotericin B and low concentrations (0.00031-0.0025 microg/mL) of essential oil was antagonistic. The strongest decrease (48%) of the MIC 80% was obtained with medium containing 0.2 microL/mL of essential oil. These results signify that the essential oil of Thymus vulgaris thymol chemotype potentiates the antifungal action of amphotericin B suggesting a possible utilization of this essential oil in addition to antifungal drugs for the treatment of mycoses.