Search

International audience; Cryptosporidium parvum is responsible for a zoonotic disease affecting both human health and livestock. The parasite infects its host through the oral route and develops in ileal epithelial cells, leading to acute and sometimes lethal diarrhoea. The severity of cryptosporidiosis is closely related to the immune status of its host, young ruminants, infants, and immunocompromised individuals being more susceptible. Other non-immune-related factors, such as digestive physicochemical properties, can also vary widely with age but their contribution to infection establishment in young individuals has never been investigated. In vitro digestion models have been designed and validated to study the fate of orally ingested substances while closely mimicking the physiological processes occurring during digestion. Among the available systems, the dynamic and multicompartmental TNO gastrointestinal model (TIM-1) is currently the most complete simulator of the human upper gastrointestinal tract. The TIM-1 was used for a comparative study of C. parvum infection under adult and young children (from 6 months to 2 years) digestive conditions. The TIM-1 was programmed to reproduce both physicochemical digestive conditions upon simulated ingestion of a glass of mineral water, which was experimentally contaminated with C. parvum oocysts. The parasite excystation kinetics throughout the course of the in vitro digestion was determined by flow cytometry analysis. Parasite invasion ability was assessed after reinoculation of sporozoites collected from the TIM-1 onto HCT-8 cells. A luciferase reporter gene assay was also used to follow sporozoite activity throughout the digestive process. Our data show that the parasite excystation rate is almost maximal in the duodenal compartment, one hour after the beginning of digestion in the TIM-1. However, a higher number of parasites reaches the distal ileal compartment while protected in their oocyst shell upon simulation of child compared to adult digestive conditions. This suggests that a lower amount of sporozoites is released in the small intestine in children, nevertheless, the luciferase activity expressed by these free stages in the ileal compartment is significantly higher in children compared to adults. Invasion assay performed on HCT-8 cells suggests that only sporozoites collected in the ileum after three hours of digestion are able to invade host cells.Our study is the first one exploring the impact of different digestive conditions on Cryptosporidium using a sophisticated gastrointestinal model. A global transcriptome analysis by RNA-Seq is also being performed on samples collected during in vitro digestion to identify parasite genes that are differentially expressed under child and adult digestive conditions.

International audience; Grouping approaches of nanomaterials have the potential to facilitate high throughput and cost effective nanomaterial screening. However, an effective grouping of nanomaterials hinges on the application of suitable physicochemical descriptors to identify similarities. To address the problem, we developed an integrated testing approach coupling acellular and cellular phases, to study the full life cycle of ingested silver nanoparticles (NPs) and silver salts in the oro-gastrointestinal (OGI) tract including their impact on cellular uptake and integrity. This approach enables the derivation of exposure-dependent physical descriptors (EDPDs) upon biotransformation of undigested nanoparticles, digested nanoparticles and digested silver salts. These descriptors are identified in: size, crystallinity, chemistry of the core material, dissolution, high and low molecular weight Ag-biomolecule soluble complexes, and are compared in terms of similarities in a grouping hypothesis. Experimental results indicate that digested silver nanoparticles are neither similar to pristine nanoparticles nor completely similar to digested silver salts, due to the presence of different chemical nanoforms (silver and silver chloride nanocrystals), which were characterized in terms of their interactions with the digestive matrices. Interestingly, the cellular responses observed in the cellular phase of the integrated assay (uptake and inflammation) are also similar for the digested samples, clearly indicating a possible role of the soluble fraction of silver complexes. This study highlights the importance of quantifying exposure-related physical descriptors to advance grouping of NPs based on structural similarities.

The ability of four enterococcal strains to survive human digestion and maintain their antibiotic resistance (AR) traits was investigated to determine the health risk posed by seafood-borne streptomycin-, erythromycin-, tetracycline- and gentamycin-resistant enterococci. After demonstrating ant(6)-I, ermB, tetO and aac(6′)-aph(2″) gene transferability by mating assays, strains were inoculated into a mussel homogenate which underwent in vitro digestion. Digestion reduced plate counts by 2–3 log; qPCR counts decreased by 1.5 log (E. faecium 22571/2), 2.5 log (E. faecalis 113324) or did not decrease (E. faecium 125745 and 6767/2). The much lower plate than qPCR counts seen in E. faecium suggested a viable-but-non-culturable (VBNC) subpopulation. Replica plating on antibiotic-supplemented agar and qPCR demonstrated that maintenance of AR traits was antibiotic-dependent, with a variable amount of erythromycin-, tetracycline- and gentamycin-resistant colonies and no streptomycin-resistant colonies. The seeking of unexpressed/lost AR genes in cells turned antibiotic-susceptible after digestion, identified aac(6′)-aph(2″) in all colonies of E. faecalis 113324 and E. faecium 6767/2, in the 40% of 125745 and in none of the E. faecium 22571/2. In conclusion, after digestion the AR traits of antibiotic-resistant (also VBNC) enterococci contained in seafood may be maintained and transferred to the human microbiota and from it to intestinal pathogens.

There are conflicting results on the release and conservation of bioactive protein sequences during in vitro digestion. Only the peptides that are released and survive may exert their action. Peptides

Angiotensin-converting enzyme (ACE)-inhibitory peptides released from camel milk after simulated gastro-intestinal digestion were identified. The hydrolysis degree increased during digestion. The highest ACE-inhibitory activity was found in the post-pancreatic −1 of milk. For the first time, we showed that IPP is released during the gastro-intestinal digestion of camel milk κ-casein. This research provides the basis to increase the exploitation of the health benefits of camel milk.

Dissertação de Mestrado em Segurança Alimentar As biotoxinas marinhas mais frequentes e abundantes em Portugal são as toxinas lipofílicas, nomeadamente as toxinas do grupo do ácido ocadaico (AO), que inclui as dinofisistoxinas (DTX1 e DTX2) e os seus derivados (DTX3), responsáveis pela intoxicação diarreica (DSP diarrhetic shellfish poisoning). A investigação da presença, variabilidade e transformação de biotoxinas marinhas em moluscos bivalves é de elevada importância não só para os consumidores e produtores de moluscos bivalves, mas também para as entidades reguladoras em segurança alimentar. Até à data, a quantidade de toxinas ingeridas nos alimentos tem sido considerada igual à quantidade de toxinas disponível para a absorção pelo corpo humano após o processo digestivo. Neste estudo, avaliou-se através de um modelo de digestão in vitro estático, a fração de AO, DTX2 e das suas formas esterificadas (DTX3), libertada do alimento para os fluidos digestivos (bioacessibilidade) em amostras naturalmente contaminadas de mexilhão, berbigão, conquilha e lingueirão. As amostras de mexilhão e conquilha apresentam regularmente um perfil de toxinas composto por AO e DTX2 nas suas formas livres, enquanto que o berbigão e o lingueirão têm uma elevada capacidade de biotransformação, o que conduz a que o seu perfil de toxinas seja constituído maioritariamente por formas esterificadas (DTX3). Amostras colhidas na costa Portuguesa foram utilizadas para avaliar a bioacessibilidade destes compostos, quer na matriz crua, como após cozedura a vapor. A Bioacessibilidade do conteúdo total de toxinas variou entre as espécies analisadas. A maior percentagem de toxinas bioacessiveis foi encontrada no mexilhão (86 ± 4 %), seguido da conquilha (74 ± 10 %), do lingueirão (71 ± 10 %) e, por último, do berbigão (59 ± 10 %). As toxinas que não se libertaram da matriz alimentar foram detetadas na fração nãobioacessivel, correspondente à fração excretada. Nas amostras de mexilhão e conquilha determinou-se mais AO na fração bioacessivel do que o presente na matriz alimentar antes da digestão. Não podendo haver mais AO do que aquele que foi ingerido, e tendo sido observado paralelamente um valor muito reduzido de AO esterificado na fração bioacessivel, sugere-se uma conversão dos compostos esterificados no composto parental durante o processo digestivo. A conversão no trato digestivo dos compostos menos tóxicos (DTX3) nos seus compostos parentais mais potentes, vem justificar os casos de intoxicação após o consumo de bivalves contendo um perfil de toxinas dominado por DTX3. No entanto, nas amostras de berbigão e lingueirão não foi observada a conversão das formas esterificadas de AO, sugerindo um perfil de formas esterificadas diferente do mexilhão e conquilha. O tratamento a vapor foi avaliado nas amostras de mexilhão e berbigão, tendo-se observado um aumento da concentração das toxinas lipofílicas, mas uma redução da bioacessibilidade dos compostos face às matrizes cruas, sendo de destacar que a bioacessibilidade estimada para as amostras de berbigão foi interior a 50%. Este estudo fornece novos dados relevantes que podem melhorar e levar a estudos de avaliação de risco em segurança alimentar mais precisos sobre estas toxinas. A avaliação de risco com base exclusivamente na ocorrência das toxinas DSP em moluscos bivalves pode conduzir a uma sobrestimação da exposição e levar a medidas regulamentares mais conservadoras do que tendo em conta a quantidade de toxinas que podem ser absorvidas pelos epitélios intestinais. ABSTRACT - In vitro bioaccessibility of the marine biotoxins okadaic acid, dinophysistoxin-2 and their derivatives in raw and steamed shellfish - The most common and abundant biotoxins in Portugal are lipophilic toxins, including okadaic acid group (OA) toxins, which includes the dinophysistoxins (DTX1 and DTX2) and its derivatives (DTX3), responsible for the human food borne illness diarrhetic shellfish poisoning (DSP). Investigating the presence, variability and processing of marine biotoxins in bivalve molluscs is highly important not only for consumers and shellfish producers but also for governmental agencies with responsibilities on food safety. To date, the amount of toxins ingested in the food has been considered equal to the amount of toxins available for uptake by the human body after the digestive process. In this study, we evaluated through a static in vitro digestion model, the fraction of OA, DTX2 and DTX3 released from the food to the digestive fluids (bioaccessibility) in naturally contaminated mussels, donax clams, cockles, and razor clams. Bioaccessibility was assessed in both raw and steamed shellfish matrices. Higher bioaccessibilty was estimated for mussels (86 ± 4 %), followed by donax clams (74 ± 10 %), razor clams (71 ± 10 %) and finally cockles (59 ± 10 %). The amount of toxins not released into the digestive juices were detected in the non-bioaccessible fraction. In mussels and donax clams higher levels of OA were determined in the digestive juices than in the food matrix. Parallel to higher amounts of OA in bioaccessible fraction was observed a reduction of its esterified forms (DTX3), suggesting that DTX3 are converted into the parental compounds during the digestion process. This gastrointestinal conversion of less potent toxins into their more toxic parental compounds can be pointed out as a reason for human food poisonings after ingestion of contaminated shellfish containing mostly DTX3, as was previously observed in Portugal. However, conversion of DTX3 into OA was not observed in cockles and razor clams, suggesting that the suite of esterified compounds in these species is different from mussels and donax clams. Steaming of shellfish matrices, simulating a cooking treatment, lead to an increase of toxins concentration but significantly reduced their bioaccessibility, which was particular evident for cockles having the release of toxins been estimated by this in vitro model to levels below 50%. This study provides relevant new data that can improve and lead to more accurate food safety risk assessment studies concerning these toxins. Risk assessment based solely on DSP toxins occurrence in seafood can conduct to an overestimation of the exposure and lead to regulatory measures more conservative than taking into account the amount of toxins that can be absorbed by the intestinal epithelia. N/A

Es caracteritzen les representacions (dibuixos i maquetes) dels models inicials sobre la digestió humana d'un grup de professores, així com la seva evolució en finalitzar un taller de capacitació. L'anàlisi es realitza en dos nivells: descriptiu i interpretatiu. En l'interpretatiu es generen quatre idees clau: continuïtat, interacció, transformació i integració, que permeten la identificació de quatre models inicials i un de final. Dels inicials, l'IV resulta completo únicament per a la idea de continuïtat. El model d'arribo resulta complet per a les idees de continuïtat i interacció i presenta canvis parcials per a la idea de transformació i absència de la idea d'integració. Es discuteix la influència del tipus de suport semiòtic, així com la utilitat de les quatre idees plantejades per a l'anàlisi de representacions i el desenvolupament d'intervencions didàctiques sobre el model de digestió humana., The characterization of representations -drawings and 3d models- of the school scientific models about human digestion of a group of teachers and its evolution in a training workshop is presented. There are analyzed using two levels: descriptive and interpretative. On interpretative level four key ideas are generated: Continuity, interaction, transformation and integration. These ideas allow a classification of four initial models and one final model. The initial model IV shows completeness for the idea of continuity; the other initial models present disorganization and bias in the four ideas. The final model presented completeness for continuity and interaction, partial changes for transformation and absence of the idea of integration. The influence of semiotic support, the usefulness of the four ideas proposed for the analysis of representations and the development of educational interventions on human digestion models are discussed., Se caracterizan las representaciones (dibujos y maquetas) de los modelos iniciales sobre la digestión humana de un grupo de profesoras, así como su evolución al finalizar un taller de capacitación. El análisis se realiza en dos niveles: descriptivo e interpretativo. En el interpretativo se generan cuatro ideas clave: continuidad, interacción, transformación e integración, que permiten la identificación de cuatro modelos iniciales y uno final. De los iniciales, el IV resulta completo únicamente para la idea de continuidad. El modelo de arribo resulta completo para las ideas de continuidad e interacción y presenta cambios parciales para la idea de transformación y ausencia de la idea de integración. Se discute la influencia del tipo de soporte semiótico, así como la utilidad de las cuatro ideas planteadas para el análisis de representaciones y el desarrollo de intervenciones didácticas sobre el modelo de digestión humana.

Se caracterizan las representaciones (dibujos y maquetas) de los modelos iniciales sobre la digestión humana de un grupo de profesoras, así como su evolución al finalizar un taller de capacitación. El análisis se realiza en dos niveles: descriptivo e interpretativo. En el interpretativo se generan cuatro ideas clave: continuidad, interacción, transformación e integración, que permiten la identificación de cuatro modelos iniciales y uno final. De los iniciales, el IV resulta completo únicamente para la idea de continuidad. El modelo de arribo resulta completo para las ideas de continuidad e interacción y presenta cambios parciales para la idea de transformación y ausencia de la idea de integración. Se discute la influencia del tipo de soporte semiótico, así como la utilidad de las cuatro ideas planteadas para el análisis de representaciones y el desarrollo de intervenciones didácticas sobre el modelo de digestión humana. Es caracteritzen les representacions (dibuixos i maquetes) dels models inicials sobre la digestió humana d'un grup de professores, així com la seva evolució en finalitzar un taller de capacitació. L'anàlisi es realitza en dos nivells: descriptiu i interpretatiu. En l'interpretatiu es generen quatre idees clau: continuïtat, interacció, transformació i integració, que permeten la identificació de quatre models inicials i un de final. Dels inicials, l'IV resulta completo únicament per a la idea de continuïtat. El model d'arribo resulta complet per a les idees de continuïtat i interacció i presenta canvis parcials per a la idea de transformació i absència de la idea d'integració. Es discuteix la influència del tipus de suport semiòtic, així com la utilitat de les quatre idees plantejades per a l'anàlisi de representacions i el desenvolupament d'intervencions didàctiques sobre el model de digestió humana. The characterization of representations -drawings and 3d models- of the school scientific models about human digestion of a group of teachers and its evolution in a training workshop is presented. There are analyzed using two levels: descriptive and interpretative. On interpretative level four key ideas are generated: Continuity, interaction, transformation and integration. These ideas allow a classification of four initial models and one final model. The initial model IV shows completeness for the idea of continuity; the other initial models present disorganization and bias in the four ideas. The final model presented completeness for continuity and interaction, partial changes for transformation and absence of the idea of integration. The influence of semiotic support, the usefulness of the four ideas proposed for the analysis of representations and the development of educational interventions on human digestion models are discussed.

Fusarium mycotoxins are secondary metabolites produced by Fusarium spp. in cereals. Among them, deoxynivalenol (DON) and zearalenone (ZEN) are widespread worldwide contaminants of cereal commodities and are ranked as the most important chronic dietary risk factors. Their conjugates, known as masked mycotoxins, have been described but are still not accounted for in risk assessment studies. This study demonstrates for the first time that DON and ZEN are effectively deconjugated by the human colonic microbiota, releasing their toxic aglycones and generating yet unidentified catabolites. For this reason, masked mycotoxins should be considered when evaluating population exposure.

En este trabajo de investigación se identificaron los modelos explicativos más frecuentes y los obstáculos más comunes en el proceso enseñanza – aprendizaje del concepto de digestión humana, en estudiantes de sexto grado de básica secundaria, reconociendo la importancia de realizar una exploración de ideas previas de los estudiantes. Se realizó el análisis de la información empleando la herramienta ATLAS TI. Una vez identificados los modelos y los obstáculos se diseñó una unidad didáctica que permita mejorar los procesos de enseñanza - aprendizaje del concepto de digestión humana empleando estrategias metacognitivas y de lenguaje que faciliten su desenvolvimiento en la vida cotidiana y facilitar la solución de problemas en diferentes situaciones y contextos. (Texto tomado de la fuente) Abstract : In this research the explanatory models frequently the most common obstacles in the teaching process were identified - learning the concept of human digestion, sixth grade students in junior high school, recognizing the importance of a preliminary exploration of student ideas. Information analysis was performed using the ATLAS IT tool. Learning the concept of human digestion and using metacognitive strategies to facilitate language development in your daily life and facilitate problem solving in different situations - Once identified models and obstacles a teaching unit that will improve the teaching was designed and contexts Maestría

A cross-sectional study of Portuguese primary school pupils' conceptions on digestion and the digestive tract was carried out before and after teaching this topic. Pupils of the prior four school years (5/6 to 9/10 year old) drew what happens to a cookie inside their body. In some cases they also wrote a short text or were interviewed. To identify their level of graphic development, they produced a free-hard drawing. The main conceptual changes in explaining digestion were strongly linked to teaching. Children’s previous conceptions were not epistemological obstacles to learning about digestion. The main obstacles were of didactical origin, as images of primary school books do not represent (i) the path of food from the intestine into the blood, (associated to the epistemological obstacle of the permeability of the gut wall); (ii) a clear continuous tract from stomach to anus, which causes a specific confusion at the intestine level., Fundação Calouste Gulbenkian (FCG) - nº 56565., Fundação para a Ciência e a Tecnologia (FCT) - Programa Operacional “Ciência, Tecnologia, Inovação” POCTI/CED/44187/2002., Fundação para a Ciência e a Tecnologia (FCT) - Universidade do Minho (U.M.). Research unit CIFPEC-LIBEC., Instituto de Inovação Educacional - nº 4/2002.

Prix de la meilleure communication orale décerné par la Société Française de Parasitologie; National audience; Cryptosporidium parvum is responsible for a zoonotic disease affecting both human health and livestock. The parasite infects its host through the oral route and develops in ileal epithelial cells, leading to acute and sometimes lethal diarrhoea. The severity of cryptosporidiosis is closely related to the immune status of its host, young ruminants, infants, and immunocompromised individuals being more susceptible. However, the impact of the gastrointestinal route the parasite takes before reaching its site of infection on the severity of the disease, has never been investigated. The in vitro computer-controlled TNO gastrointestinal model (TIM) was used for a comparative study of C. parvum survival and virulence under adult and child digestive conditions. Parasite survival and excystation kinetics in the in vitro digestive tract were determined by flow cytometry analysis while virulence was assessed after reinoculation of sporozoites onto HCT-8 cells. A luciferase reporter gene was also used to follow sporozoite activity throughout the digestive process. A global transcriptome analysis by RNA-Seq will be performed to identify differentially expressed parasite genes. Preliminary data show that the excystation rate is almost maximal in the duodenal compartment, one hour after the beginning of digestion in the TIM. However, a higher amount of parasites reaches the distal ileal compartment while protected in their oocyst shell upon simulation of child compared to adult digestive conditions. After three hours of digestion, the luciferase activity expressed by released sporozoites is significantly higher in the distal intestinal compartments of child compared to adult. Differences in digestive physicochemical parameters may partially explain why children are more susceptible to cryptosporidiosis than adults. This study is the first one exploring the impact of various digestive conditions on Cryptosporidium using a sophisticated gastrointestinal model.