Concentration addition, independent action and generalized concentration addition models for mixture effect prediction of sex hormone synthesis in vitro

Humans are concomitantly exposed to numerous chemicals. An infinite number of combinations and doses thereof can be imagined. For toxicological risk assessment the mathematical prediction of mixture effects, using knowledge on single chemicals, is therefore desirable. We investigated pros and cons of the concentration addition (CA), independent action (IA) and generalized concentration addition (GCA) models. First we measured effects of single chemicals and mixtures thereof on steroid synthesis in H295R cells. Then single chemical data were applied to the models; predictions of mixture effects were calculated and compared to the experimental mixture data. Mixture 1 contained environmental chemicals adjusted in ratio according to human exposure levels. Mixture 2 was a potency adjusted mixture containing five pesticides. Prediction of testosterone effects coincided with the experimental Mixture 1 data. In contrast, antagonism was observed for effects of Mixture 2 on this hormone. The mixtures contained chemicals exerting only limited maximal effects. This hampered prediction by the CA and IA models, whereas the GCA model could be used to predict a full dose response curve. Regarding effects on progesterone and estradiol, some chemicals were having stimulatory effects whereas others had inhibitory effects. The three models were not applicable in this situation and no predictions could be performed. Finally, the expected contributions of single chemicals to the mixture effects were calculated. Prochloraz was the predominant but not sole driver of the mixtures, suggesting that one chemical alone was not responsible for the mixture effects. In conclusion, the GCA model seemed to be superior to the CA and IA models for the prediction of testosterone effects. A situation with chemicals exerting opposing effects, for which the models could not be applied, was identified. In addition, the data indicate that in non-potency adjusted mixtures the effects cannot always be accounted for by single chemicals

La RMN portable pour caractériser les racines de plantes prairiales

ISITE Cap 2020-2025International audienceCette étude montre que la RMN portable permet de caractériser la structure des systèmes racinaires d'espèces prairiales contrastées mais également la fonction de ces racine

LA RMN PORTABLE POUR CARACTERISER LES RACINES DE PLANTES PRAIRIALES

International audienc

Zoo and wildlife medical education: a European perspective

Europe has a long and distinguished history in veterinary science and education, and it was here that the first professional investigations of pathological conditions in zoo animals took place. However, despite an increasing number of veterinarians working with wildlife, education in zoological and wildlife medicine has only recently become part of formal veterinary training at the undergraduate level. Consequently, current educational opportunities in zoological and wildlife medicine vary widely throughout Europe, both in availability and in composition. The need to establish agreed standards in education across Europe and to foster the mobility of students and teaching staff are reflected by international agreements such as the Bologna Treaty and the ERASMUS-SOCRATES program. Europe is also home to a number of voluntary professional organizations, such as the European Wildlife Disease Association and the European Association of Zoo and Wildlife Veterinarians, that actively promote the inclusion of zoological and wildlife medicine in veterinary education. Zoo and wildlife medicine is currently a veterinary specialization in Europe, but educational opportunities are likely to increase in availability in the future

Fifteen Years after “Wingspread”—Environmental Endocrine Disrupters and Human and Wildlife Health: Where We are Today and Where We Need to Go

In 1991, a group of expert scientists at a Wingspread work session on endocrine-disrupting chemicals (EDCs) concluded that “Many compounds introduced into the environment by human activity are capable of disrupting the endocrine system of animals, including fish, wildlife, and humans. Endocrine disruption can be profound because of the crucial role hormones play in controlling development.” Since that time, there have been numerous documented examples of adverse effects of EDCs in invertebrates, fish, wildlife, domestic animals, and humans. Hormonal systems can be disrupted by numerous different anthropogenic chemicals including antiandrogens, androgens, estrogens, AhR agonists, inhibitors of steroid hormone synthesis, antithyroid substances, and retinoid agonists. In addition, pathways and targets for endocrine disruption extend beyond the traditional estrogen/androgen/thyroid receptor–mediated reproductive and developmental systems. For example, scientists have expressed concern about the potential role of EDCs in increasing trends in early puberty in girls, obesity and type II diabetes in the United States and other populations. New concerns include complex endocrine alterations induced by mixtures of chemicals, an issue broadened due to the growing awareness that EDCs present in the environment include a variety of potent human and veterinary pharmaceutical products, personal care products, nutraceuticals and phytosterols. In this review we (1) address what have we learned about the effects of EDCs on fish, wildlife, and human health, (2) discuss representative animal studies on (anti)androgens, estrogens and 2,3,7,8-tetrachlorodibenzo-p-dioxin–like chemicals, and (3) evaluate regulatory proposals being considered for screening and testing these chemicals

The Ability of Integrin α(v)β(3) To Function as a Receptor for Foot-and-Mouth Disease Virus Is Not Dependent on the Presence of Complete Subunit Cytoplasmic Domains

The integrin α(v)β(3) has been shown to function as one of the integrin receptors on cultured cells for foot-and-mouth disease virus (FMDV), and high-efficiency utilization of the bovine homolog of this integrin is dependent on the cysteine-rich repeat region of the bovine β(3) subunit. In this study we have examined the role of the cytoplasmic domains of the α(v) and β(3) subunits in FMDV infection. We have found that truncations or extensions of these domains of either subunit, including deletions removing almost all of the cytoplasmic domains, had little or no effect on the ability of the integrin to function as a receptor for FMDV. The lysosomotropic agent monensin inhibited viral replication in cells transfected with either intact or cytoplasmic domain-truncated α(v)β(3). In addition, viral replication in transfected cells was inhibited by an α(v)β(3) function-blocking antibody but not by function-blocking antibodies to three other RGD-directed integrins, suggesting that these integrins are not involved in the infectious process. These results indicate that alterations to the cytoplasmic domains of either subunit, which lead to the inability of the integrin receptor to function normally, do not abolish the ability of the integrin to bind and internalize this viral ligand