The putative thyroid-disrupting properties of bisphenol A (BPA) highlight the need for an evaluation of fetal exposure and its consequence on the mother/newborn thyroid functions in models relevant ...to human. The goals of this study were to characterize in sheep a relevant model for human pregnancy and thyroid physiology, the internal exposures of the fetuses and their mothers to BPA and its main metabolite BPA-glucuronide (Gluc), and to determine to what extent it might be associated with thyroid disruption. Ewes were treated with BPA 5 mg/(kg . d) sc or vehicle from d 28 until the end of pregnancy. Unconjugated BPA did not appear to accumulate in pregnant ewes, and its concentration was similar in the newborns and their mothers (0.13 +/- 0.02 and 0.18 +/- 0.03 nmol/ml in cord and maternal blood, respectively). In amniotic fluid and cord blood, BPA-Gluc concentrations were about 1300-fold higher than those of BPA. Total T-4 concentrations were decreased in BPA-treated pregnant ewes and in the cord and the jugular blood of their newborns (30% decrease). A similar difference was observed for free T-4 plasma concentrations in the jugular blood of the newborns. Our results show in a long-gestation species with a similar regulatory scheme of thyroid function as humans that BPA in utero exposure can be associated with hypothyroidism in the newborns. If such an effect were to be confirmed for a more relevant exposure scheme to BPA, this would constitute a major issue for BPA risk assessment.
The putative thyroid-disrupting properties of bisphenol A (BPA) highlight the need for an evaluation of fetal exposure and its consequence on the mother/newborn thyroid functions in models relevant ...to human. The goals of this study were to characterize in sheep a relevant model for human pregnancy and thyroid physiology, the internal exposures of the fetuses and their mothers to BPA and its main metabolite BPA-glucuronide (Gluc), and to determine to what extent it might be associated with thyroid disruption. Ewes were treated with BPA 5 mg/(kg . d) sc or vehicle from d 28 until the end of pregnancy. Unconjugated BPA did not appear to accumulate in pregnant ewes, and its concentration was similar in the newborns and their mothers (0.13 +/- 0.02 and 0.18 +/- 0.03 nmol/ml in cord and maternal blood, respectively). In amniotic fluid and cord blood, BPA-Gluc concentrations were about 1300-fold higher than those of BPA. Total T-4 concentrations were decreased in BPA-treated pregnant ewes and in the cord and the jugular blood of their newborns (30% decrease). A similar difference was observed for free T-4 plasma concentrations in the jugular blood of the newborns. Our results show in a long-gestation species with a similar regulatory scheme of thyroid function as humans that BPA in utero exposure can be associated with hypothyroidism in the newborns. If such an effect were to be confirmed for a more relevant exposure scheme to BPA, this would constitute a major issue for BPA risk assessment.
L'utilisation de variétés de plantes résistantes constitue un moyen de lutte majeur contre les insectes ravageurs, une alternative particulièrement séduisante à l'utilisation de pesticides dont les ...résidus sont dommageables tout autant pour la santé des consommateurs que pour l'environnement. La résistance est considérée ici comme l'aptitude héritable de certaines plantes au sein d'une espèce végétale de limiter le développement et les dégâts provoqués par les insectes ravageurs; celle-ci repose sur la présence de gènes de résistance. De très nombreux exemples de résistance aux insectes, correspondant à toutes sortes de mécanismes, ont été décrits chez les plantes cultivées. Cependant, seul un petit nombre d'entre eux a fait l'objet d'études génétiques et un nombre plus réduit encore a fait l'objet de programmes de sélection conduisant à des variétés cultivées. Dans ce chapitre, nous nous attacherons à décrire la diversité génétique disponible pour la résistance aux insectes chez les espèces cultivées et à retracer les avancées récentes des connaissances sur les bases génétiques et moléculaires de ces résistances. Bien que les connaissances sur les interactions plantes-insectes soient très en retrait par rapport aux interactions plantes-pathogènes, des avancées notables ont été réalisées au cours des dernières années.
Paper in French Since the beginning of 2000s, imports of frozen pieces of chicken from the European Union or Brazil have considerably increased in several African and Caribbean developing countries, ...competing with local chicken meat. Obviously, imported chicken has replaced domestic one in households’ consumption. The level of substitution between imported chicken and the several domestic chicken types is not specifically known. In order to focus on this point, investigations have been done in 2005 in Yaoundé (Cameroon) and in 2006 in Port-au-Prince (Haiti). Because of a lack of available statistical data, we surveyed 180 urban households in each country, showing that imported frozen pieces of chicken have widely substituted for the local chicken which has already quite disappeared in Port-au-Prince, but is still appreciated by Yaoundé consumers. This article aims to assess the impacts, on such an evolution of i) socio-economic features of consumers and ii) of chicken consumption habits of households. Without data on income, and to deal with a large number of qualitative variables, we implemented multiple correspondence analyses to build asset indexes usable in our econometric regressions.
Since the beginning of 2000s, imports of frozen pieces of chicken from the European Union or Brazil have considerably increased in several African and Caribbean developing countries, competing with ...local chicken meat. Obviously, imported chicken has replaced domestic one in households’ consumption. The level of substitution between imported chicken and the several domestic chicken types is not specifically known. In order to focus on this point, investigations have been done in 2005 in Yaoundé (Cameroon) and in 2006 in Port-au-Prince (Haiti). Because of a lack of available statistical data, we surveyed 180 urban households in each country, showing that imported frozen pieces of chicken have widely substituted for the local chicken which has already quite disappeared in Port-au-Prince, but is still appreciated by Yaoundé consumers. This article aims to assess the impacts, on such an evolution of i) socio-economic features of consumers and ii) of chicken consumption habits of households. Without data on income, and to deal with a large number of qualitative variables, we implemented multiple correspondence analyses to build asset indexes usable in our econometric regressions.
Depuis le début des années 2000, les importations de volaille congelée en provenance d’Europe et d’Amérique se sont considérablement développées dans plusieurs pays en développement d’Afrique et des Caraïbes, concurrençant les productions locales de poulet. En revanche, le degré de substitution, dans la consommation des ménages, entre le poulet importé et les différents types de poulet produits localement, est mal connu. De façon à préciser cet aspect, et du fait du manque de données statistiques à ce niveau de précision, des enquêtes ont été menées, en 2005 à Yaoundé (Cameroun) puis en 2006 à Port au Prince (Haïti), auprès de 180 ménages urbains dans chaque pays. Les résultats montrent que les découpes importées de poulet congelé se sont effectivement largement substituées au poulet local : ce dernier a presque disparu à Port-au-Prince, mais reste apprécié des consommateurs à Yaoundé. Cet article approfondit la question des déterminants de cette évolution en évaluant le rôle joué d’une part par la situation socio-économique des ménages urbains, et d’autre part par les modes de consommation de poulet des ménages. De façon à prendre en compte les très nombreuses variables qualitatives, les régressions économétriques utilisent des variables synthétiques continues construites sur la base d’analyse des correspondances multiples.
Since the beginning of 2000s, imports of frozen pieces of chicken from the European Union or Brazil have considerably increased in several African and Caribbean developing countries, competing with ...local chicken meat. Obviously, imported chicken has replaced domestic one in households’ consumption. The level of substitution between imported chicken and the several domestic chicken types is not specifically known. In order to focus on this point, investigations have been done in 2005 in Yaoundé (Cameroon) and in 2006 in Port-au-Prince (Haiti). Because of a lack of available statistical data, we surveyed 180 urban households in each country, showing that imported frozen pieces of chicken have widely substituted for the local chicken which has already quite disappeared in Port-au-Prince, but is still appreciated by Yaoundé consumers. This article aims to assess the impacts, on such an evolution of i) socio-economic features of consumers and ii) of chicken consumption habits of households. Without data on income, and to deal with a large number of qualitative variables, we implemented multiple correspondence analyses to build asset indexes usable in our econometric regressions.
Depuis le début des années 2000, les importations de volaille congelée en provenance d’Europe et d’Amérique se sont considérablement développées dans plusieurs pays en développement d’Afrique et des Caraïbes, concurrençant les productions locales de poulet. En revanche, le degré de substitution, dans la consommation des ménages, entre le poulet importé et les différents types de poulet produits localement, est mal connu. De façon à préciser cet aspect, et du fait du manque de données statistiques à ce niveau de précision, des enquêtes ont été menées, en 2005 à Yaoundé (Cameroun) puis en 2006 à Port au Prince (Haïti), auprès de 180 ménages urbains dans chaque pays. Les résultats montrent que les découpes importées de poulet congelé se sont effectivement largement substituées au poulet local : ce dernier a presque disparu à Port-au-Prince, mais reste apprécié des consommateurs à Yaoundé. Cet article approfondit la question des déterminants de cette évolution en évaluant le rôle joué d’une part par la situation socio-économique des ménages urbains, et d’autre part par les modes de consommation de poulet des ménages. De façon à prendre en compte les très nombreuses variables qualitatives, les régressions économétriques utilisent des variables synthétiques continues construites sur la base d’analyse des correspondances multiples.
In order to explore the potentiality of hydrazinopeptides as protease inhibitors, the resistance of the hydrazinopeptidic bond toward proteolysis was investigated. To this end, the novel ...hydrazinohexapeptide Z-Ala2-Pro-Val-hIle-Leu-OMe (1), where hIle represents hydrazinoisoleucine, was designed and synthesized together with the parent peptide Z-Ala2-Pro-Val-Ile-Leu-OMe (2). The interactions of 1 and 2 with human leukocyte elastase (HLE) and porcine pancreatic elastase (PPE) were analyzed comparatively. We observed that 1 behaved as a substrate for both elastases, without the formation of a stable acyl-enzyme as in the case of azapeptides. Compounds 1 and 2 were cleaved at the same site (-Val-parallel-NH-) with a slight delay of hydrolysis for 1 compared to 2 (kcat/KM for 1 vs. 2 decreased by a factor of 2.7 for the HLE-catalyzed hydrolysis at pH 8.0 and 25 degrees C). The presence of the hydrazinopeptide bond (-CONHNH-) in 1 reduced by a factor of 4.7 the apparent enzyme affinity without abolishing it. These results indicate that suitably designed hydrazinopeptides may represent interesting targets in the search for protease resisting pseudopeptides.
Using dogs as a valid model, we compared plasma concentrations of BPA over a 24-hr period after intravenous, orogastric, and sublingual administration in order to establish the absolute ...bioavailability of BPA administered sublingually and to compare it with oral bioavailability.
Our findings demonstrate that BPA can be efficiently and very rapidly absorbed through the oral mucosa after sublingual exposure. This efficient systemic entry route of BPA may lead to far higher BPA internal exposures than known for BPA absorption from the gastrointestinal tract.
Bisphenol A (BPA) risk assessment is currently hindered by the rejection of reported higher-than-expected plasma BPA concentrations in humans after oral ingestion. These are deemed incompatible with the almost complete hepatic first-pass metabolism of BPA into its inactive glucurono-conjugated form, BPA glucuronide (BPAG).
Six dogs were sublingually administered BPA at 0.05 mg/kg and 5 mg/kg. We compared the time course of plasma BPA concentrations with that obtained in the same dogs after intravenous administration of the same BPA doses and after a 20-mg/kg BPA dose administrated by orogastric gavage.
The data indicated that the systemic bioavailability of BPA deposited sublingually was high (70-90%) and that BPA transmucosal absorption from the oral cavity led to much higher BPA internal exposure than obtained for BPA absorption from the gastrointestinal tract. The concentration ratio of BPAG to BPA in plasma was approximately 100-fold lower following sublingual administration than after orogastric dosing, distinguishing the two pathways of absorption.
