Search results for "toxin"
showing 10 items of 1434 documents
A nonsense mutation abrogates production of a functional enterotoxin A in Clostridium difficile toxinotype VIII strains of serogroups F and X.
1999
Clostridium difficile strains of toxinotype VIII from serogroups F and X are described as toxin B-positive, toxin A-negative (TcdB+ A-), although they harbour almost the entire tcdA gene. To identify the reason for the lack of TcdA detection, we analyzed catalytic and ligand domains of TcdA-1470 of the type strain of serogroup F, strain 1470. Using recombinant fragments, the C-terminal immunodominant ligand domain TcdA3-1470, spanning amino acid residues 1694-2711 (corresponding to VPI 10463 sequence), was detected in Western blots. Similar experiments using the recombinant N-terminal catalytic fragment TcdAc1-2-1470 (amino acid positions 1-544) failed. In addition, this fragment showed no …
Potent membrane-permeabilizing and cytocidal action of Vibrio cholerae cytolysin on human intestinal cells
1997
Many strains of Vibrio cholerae non-O1 and O1 El Tor that cause diarrhea do not harbor genes for a known secretogenic toxin. However, these strains usually elaborate a pore-forming toxin, hitherto characterized as a hemolysin and here designated V. cholerae cytolysin, whose action on intestinal cells has not yet been described. We report that V. cholerae cytolysin binds as a monomer to Intestine 407 cells and then assembles into detergent-stable oligomers that probably represent tetra- or pentamers. Oligomer formation is accompanied by generation of small transmembrane pores that allow rapid flux of K+ but not influx of Ca2+ or propidium iodide. Pore formation is followed by irreversible AT…
Occurrence and exposure assessment of mycotoxins in ready-to-eat tree nut products through ultra-high performance liquid chromatography coupled with …
2020
Tree nuts have become popular snacks due to their attributed benefits in the health state. Nevertheless, their susceptibility to fungal contamination lead to the occurrence of potentially dangerous mycotoxins. Hence, the aim of this work was to evaluate the presence of mycotoxins in ready-to-eat almonds, walnuts, and pistachios from Italian markets. The most relevant mycotoxin found in almonds was α-zearalanol in 18% of samples (n = 17) ranging from 3.70 to 4.54 µg/kg. Walnut samples showed frequent contamination with alternariol, present in 53% of samples (n = 22) at levels from 0.29 to 1.65 µg/kg. Pistachios (n = 15) were the most contaminated commodity, with β-zear…
Grape and environmental mycoflora monitoring in old, traditionally-cultivated vineyards on Mount Etna, southern Italy
2015
BACKGROUND: Grape contamination by several fungal species occurs during a vineyard's preharvest and harvest. Agronomic management and microclimatic conditions can affect fungi occurrence and epidemiology, thus explaining qualitative differences in mycoflora composition, including the presence of phytopathogenic or mycotoxigenic fungi. In this study a two-year grape, air and soil mycoflora monitoring programme was undertaken in vineyards on Mount Etna (eastern Sicily, Italy). The mycoflora composition was investigated at pea berry and veraison phenological phases from air and soil and at ripening from sample grapes. RESULTS: Mycoflora in air and soil varied according to the phenological stag…
Effects of technological processes on enniatin levels in pasta
2015
BACKGROUND Potential human health risks posed by enniatins (ENs) require their control primarily from cereal products, creating a demand for harvesting, food processing and storage techniques capable to prevent, reduce and/or eliminate the contamination. In this study, different methodologies to pasta processing simulating traditional and industrial processes were developed in order to know the fate of the mycotoxin ENs. The levels of ENs were studied at different steps of pasta processing. The effect of the temperature during processing was evaluated in two types of pasta (white and whole-grain pasta). Mycotoxin analysis was performed by LC-MS/MS. RESULTS High reductions (up to 50% and 80%…
Analysis of mycotoxins in coffee and risk assessment in Spanish adolescents and adults.
2015
Mycotoxins are toxic compounds produced by fungal secondary metabolism that cause toxicological effects. Coffee is a highly popular beverage that is susceptible to contamination by mycotoxigenic fungi. The aim of the present study was to determine the presence of the following 21 mycotoxins in coffee using liquid chromatography tandem mass spectrometry (LC-MS/MS-IT): aflatoxin B1, B2, G1 and G2; ochratoxin A; nivalenol; deoxynivalenol; 3-acetyldeoxynivalenol; 15-acetyldeoxynivalenol; diacetoxyscirpenol; neosolaniol; T-2 and HT-2 toxin; sterigmatocystin; enniatin A, A1, B, and B1; beauvericin; and fumonisin B1 and B2. We aimed to determine differences by coffee process (coffee maker, electri…
Ochratoxin A levels in the plasma of healthy blood donors from Valencia and estimation of exposure degree: comparison with previous national Spanish …
2010
Blood plasma levels of ochratoxin A, a toxic secondary metabolite of several fungal species belonging to the genera Aspergillus and Penicillium, were determined in 168 blood donors from the population of Valencia (Spain) using LC-FLD. In conjunction with blood collection, detailed information on diet was obtained by using a questionnaire that encompassed a wide range of products potentially contaminated with the toxin. The investigation revealed a detection frequency of 100%. Mean level was 1.09 microg OTA/l of plasma and concentrations ranged between 0.15 and 5.71 microg OTA/l of plasma. Men's levels were slightly higher than levels observed in women. Results were analysed by Spearman rank…
Assessment of Human Exposure to Deoxynivalenol, Ochratoxin A, Zearalenone and Their Metabolites Biomarker in Urine Samples Using LC-ESI-qTOF.
2021
Human are exposed to a wide range of mycotoxins through dietary food intake, including processed food. Even most of the mycotoxin exposure assessment studies are based on analysis of foodstuffs, and evaluation of dietary intake through food consumption patterns and human biomonitoring methods are rising as a reliable alternative to approach the individual exposures, overcoming the limitations of the indirect dietary assessment. In this study, human urine samples were analyzed, seeking the presence of deoxynivalenol (DON), ochratoxin A (OTA), zearalenone (ZEA), and their metabolites. For this purpose, 40 urine samples from female and male adult residents in the city of Valencia (Spain) were …
Dietary Exposure to Mycotoxins through Alcoholic and Non-Alcoholic Beverages in Valencia, Spain
2021
The present study investigated the presence of 30 mycotoxins in 110 beverage samples of beer, wine, cava, and cider purchased in Valencia (Spain). A validated method based on dispersive liquid–liquid microextraction and chromatographic methods coupled with tandem mass spectrometry was applied. The method showed satisfactory recoveries ranging from 61 to 116% for the different beverages studied. The detection and quantification limits ranged from 0.03 to 2.34 µg/L and 0.1 to 7.81 µg/L, respectively. The results showed that beer samples were the most contaminated, even with concentrations ranging from 0.24 to 54.76 µg/L. A significant presence of alternariol was found in wine, which reached c…
Multi-mycotoxin contamination of green tea infusion and dietary exposure assessment in Moroccan population
2021
Green tea infusion is one of the most widely drunk beverages worldwide due to its health benefits associated with microelements, essential oils, and polyphenols, etc. Several studies have reported that green tea is subjected to contamination by various toxigenic fungi. Thus, this work aims to investigate the co-occurrence of 15 mycotoxins [four aflatoxins (AFB1, AFB2, AFG1, AFG2), ochratoxin A (OTA), beauvericin (BEA), four enniatins (ENA, ENA1, ENB, ENB1), zearalenone (ZEN), alternariol (AOH), tentoxin (TENT), T-2 and HT-2 toxins] in green tea samples available in Morocco by liquid chromatography tandem mass spectrometry method. Analytical and consumption data were then used to assess the …