RESUMEN
Ochratoxin A (OTA) is a toxic metabolite, produced by Aspergillus spp. and Penicillium verrucosum, that is nephrotoxic and possibly carcinogenic to humans. The aim of this study was to evaluate OTA contamination in batches of green coffee destined for export. Analysis of 80 green coffee samples indicated that, although a high incidence (74%) of OTA contamination (0.2-13.5 ng g⻹) was recorded, the overall mean OTA level (2.17 ± 2.45 ng g⻹) was low. The highest recorded OTA concentration was 13.5 ng g⻹ in a robusta cherry sample and only five samples had OTA above 5 ng g⻹ level. The mean OTA level was higher in cherry (range: 1.63 ± 0.97-4.8 ± 3.90) than parchment (0.56 ± 0.35-1.10 ± 0.28), indicating a correlation between processing method and OTA contamination.
Asunto(s)
Carcinógenos/análisis , Coffea/química , Contaminación de Alimentos , Manipulación de Alimentos , Ocratoxinas/análisis , Venenos/análisis , Semillas/química , Métodos Analíticos de la Preparación de la Muestra , Cromatografía de Afinidad , Cromatografía Líquida de Alta Presión , Cromatografía de Fase Inversa , Café/química , Café/economía , Café/normas , Inspección de Alimentos , Adhesión a Directriz , India , Límite de Detección , Reproducibilidad de los Resultados , Espectrometría de FluorescenciaRESUMEN
The effects of lipopolysaccharide (LPS) and/or inflammatory cytokines on the expression of inducible nitric oxide synthase (iNOS) were studied in mIMCD-3 cells, derived from the murine inner medullary collecting duct. Under basal conditions, the production of nitrite, a stable metabolite of NO, was negligible; however, incubation with tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IF-gamma) for 24 h resulted in a 12-fold increase in nitrite synthesis and the appearance of abundant iNOS mRNA and protein. The induction of nitrite production and iNOS mRNA was time dependent, requiring approximately 8 h for expression of significant levels of nitrite or iNOS mRNA. Coincubation with the transcription inhibitor actinomycin D or the translation inhibitor cycloheximide prevented the cytokine induction of iNOS mRNA and NO production, indicating that synthesis of intermediary proteins stimulated transcription of the iNOS gene. Nuclear run-on transcription demonstrated that the iNOS gene was transcriptionally inactive under basal conditions, but was markedly induced by TNF-alpha and IF-gamma. These results indicate that inflammatory cytokines stimulate NO production in mIMCD-3 cells by activating iNOS gene transcription in a process that requires new protein synthesis.