On the deformability of additivated phosphatidylcholine liposomes: Molecular dynamic regimes and membrane elasticity.

Liposomes with enhanced elasticity have been proven to increase the efficiency of drug transport across the skin. The understanding of the background physicochemical processes driving the liposome viscoelastic properties is an essential feature for the design of effective formulations involving different lipids and additive molecules. In this work we use field-cycled nuclear magnetic resonance relaxometry to analyze both the mechanical properties of liposome membranes, and their relationship with the involved molecular dynamics. Different liposomal formulations were considered. We show a correlation between the molecular dynamical regime and mesoscopic physical parameters that define the expected deformability of the vesicles. Results strongly suggest that the purity of the used lipids may influence the elastic properties of the membranes in an appreciable way. Common features in the behaviour of the involved dynamic variables were identified by comparing formulations with surfactants of similar molecular weight.

Exposure assessment to ochratoxin A in Catalonia (Spain) based on the consumption of cereals, nuts, coffee, wine, and beer.

Ochratoxin A (OTA) was analysed in composite samples of cereal-based baby foods, beer, breakfast cereals (corn- and rice and wheat-based), loaf bread, peanuts and pistachios. Foodstuffs were collected in hypermarkets and supermarkets from 12 cities in the Spanish region of Catalonia, and composite samples were prepared for analysis involving liquid-liquid extraction, followed by immunoaffinity column clean-up and HPLC with fluorescence detection. Consumption data for the selected foodstuffs were collected by means of a food-frequency questionnaire. The studied population was grouped by age in infants, children, adolescents and adults; and exposure to OTA through the specified foodstuffs, and through wine and coffee, was assessed. Exposure assessment was done through deterministic and probabilistic modelling of the contamination and consumption data. OTA occurrence and mean of positive samples (ng g(-1) or ng ml(-1), for beer) were the following: 8.7% and 0.233 in baby foods; 88.7% and 0.022 in beer; 2.8% and 0.728 in corn-based breakfast cereals; 25% and 0.293 in wheat-based breakfast cereals; 12.9% and 0.283 in loaf bread; 41.7% and 0.241 in peanuts; and 2.9% and 0.228 in pistachios. The median estimated daily intake of OTA through the foodstuffs by each age group were below the latest provisional tolerable daily intakes (PTDIs) of 17 and 14 ng kg(-1) bw day(-1) recommended by the European Food Safety Authority (EFSA) in 2006 and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2007, respectively, ranging from 1% and 2% of those values in adolescents and children, to 3% and 11% in adults and infants.

Ochratoxin A in adult population of Lleida, Spain: presence in blood plasma and consumption in different regions and seasons.

Ochratoxin A (OTA) levels in blood plasma, as well as the consumption of possibly contaminated foodstuffs by adult inhabitants, were determined in three seasons in the plain and the mountain regions of the province of Lleida (Spain). Daily intake of the toxin was estimated in order to evaluate the exposure of the studied population. OTA was extracted from plasma through liquid-liquid extraction followed by immunoaffinity chromatography columns clean-up. Detection was done through HPLC-fluorescence, and limit of detection was 0.018ng/mL. Consumption data of the participants were obtained by means of a food frequency questionnaire. Occurrence of OTA in plasma was 100%. Range was 0.06-10.92ng/mL, and median was 0.50ng/mL. Differences between genders, regions or seasons were not significant, whereas significant differences were found among age groups. Regarding food consumption, significant differences were found between genders, but not between age groups, regions, or seasons. OTA plasma levels were not correlated with food consumption. Distributions of the intake estimations based on plasma levels differed from those based on food consumption and contamination. Mean and median values of the daily intake estimations were below the latest provisional tolerable daily intake of 14ng/kgbw/day, but some high percentiles were above it.

Sphinganine and sphingosine levels and ratio in urine and blood samples from a Catalonian population, Spain.

Fumonisins occur mainly in maize and they produce alterations on sphingolipid metabolism, unbalancing the sphinganine (Sa)/sphingosine (So) ratio. This alteration has been proposed as a biomarker of fumonisin exposure. The objective of this study was to establish the urinary and plasmatic levels of Sa, So as well as the ratio Sa/So from a sample of the Catalonian (Spain) population exposed to fumonisins at low levels. Firstly, plasma and urinary Sa and So levels and the ratio Sa/So were compared between two population groups, and later urinary Sa and So levels from corn food consumers and a control group were monitored for 2 weeks under controlled intake of corn foods. Sa and So levels were determined in urine and blood samples using validated methods using HPLC with fluorescence detection. Significant differences were not found in urine samples when Sa/So ratios were compared from corn food consumers and non-consumers, while significant differences were found in urine and plasma samples, but evidence of the mechanism of action of fumonisins was not apparent. Through a time-course study we have narrowed down the day in which the maximum alteration of Sa/So ratio should be expected in humans. This paper reports some useful information to improve the design of studies to validate the ratio Sa/So as a possible biomarker of fumonisin exposure.

Ochratoxin A and its metabolite ochratoxin alpha in urine and assessment of the exposure of inhabitants of Lleida, Spain.

Ochratoxin A (OTA) as well as its metabolite ochratoxin α (OTα) were detected in human urine in order to assess the exposure to OTA of a group of 72 adult inhabitants of the city of Lleida (Spain). Urine samples were enzymatically treated; OTA and OTα were separated by liquid-liquid extraction, and detected by HPLC-fluorescence. Exposure to OTA was also evaluated by the estimation of its daily intake from food contamination data from the literature and from food consumption data provided by the participants, who filled in a food frequency questionnaire (FFQ) and a three-day food consumption record (3DR). OTA occurrence (12.5%, limit of detection=0.034 ng/mL) was lower than OTα occurrence (61.1%, limit of detection=0.023 ng/mL). The range of concentrations was 0.057-0.562 ng/mL and 0.056-2.894 ng/mL for OTA and for OTα, respectively. It could be observed for positive samples that the FFQ data were related to the OTA concentration in urine, whereas the 3DR data were related to the OTα levels in urine. The OTA estimated daily intake of the participants was lower than 30% of the latest provisional tolerable daily intake of 14 ng/kg body weight/day in the worst cases of exposure.

Review. Ochratoxin A: presence in human plasma and intake estimation.

Ochratoxin A (OTA) is a fungal toxic secondary metabolite that can be found in several foodstuffs and thereby ingested by humans. One way to assess exposure of humans to OTA is the determination of the levels of this mycotoxin in blood plasma from a certain population. Such studies have been done in many countries, both in healthy people and nephropathy patients. Relationships with individual characteristics were investigated in several cases. Thus, most studies found no correlation with age, either with gender. However, the few studies that found correlation between OTA plasma levels and gender showed that men presented the highest values. When sampling was done over more than one season, the highest OTA plasma levels were found mostly in summer. Differences within regions of a country were related to dietary habits of each area. OTA levels of group populations showed variations from year to year, whereas intraindividual repetitions showed no specific trend. Daily intake of the toxin can be estimated from OTA plasma concentrations by the Klaassen equation. OTA toxicokinetics are considered in this review. Calculated daily intake of OTA by different studies did not overpass the proposed tolerable daily intakes of OTA.

Assessment of the exposure to ochratoxin A in the province of Lleida, Spain.

Exposure to ochratoxin A (OTA) of 279 blood donors of nine localities of the province of Lleida (Spain) was assessed. OTA levels were detected in the blood plasma of the participants by HPLC-fluorescence detection with previous clean-up of the samples by immunoaffinity columns. Limit of detection was 0.075 ng/mL. Participants answered a questionnaire on consumption frequency of foods possibly contaminated with OTA. Foodstuffs were grouped: cereals and derived products, dried fruits and derived products, cacao and derived products, grape juice, wine, beer and coffee. The range of positive samples was 0.11-8.68 ng/mL and the median was 0.54 ng/mL. No differences were found between OTA plasma levels in men and women, neither in the different localities, but there were significant differences among three age groups. Highest consumed foods were cereals and derived products, followed by beer and wine. No correlation was found between food consumption and OTA plasma levels. OTA daily intake was estimated based on OTA plasma concentrations and on the food consumption data combined with food contamination data taken from the literature. Mean values were 1.69 and 1.96 ng/kg body weight/day, respectively. These values are below the latest proposed tolerable daily intake of 14 ng/kg body weight/day.