A PARAMETRIC ANALYSIS FOR THE DAFALIAS-KALIAKIN BOUNDING SURFACE VISCOPLASTIC MODEL-BASED ON THE DIFLUPRESS LD TEST

In order to predict delayed settlements of heavy structures, the authors decided to use the elasto-viscoplastic model of Dafalias-Kaliakin. To identify the parameters of the constitutive equations, they use above all the data of a new in-situ test, the Diflupress L.D. designed to approach the creep behavior of soil. In a first section, the principle of the model is presented. Then, the important parameters of the model are identified, mostly from in-situ test data since the laboratory tests data are not numerous and reliable. Finally, a study of sensitivity on the parameters which influence the viscoplastic response of the model is made

The current environmental levels of endocrine disruptors (mercury, cadmium, organochlorine pesticides and PCBs) in a Belgian adult population and their predictors of exposure

A human biomonitoring study was carried out measuring the levels of endocrine disruptors in 252 participants (18-76 years old) recruited between February and May 2015 from the general population of Liege Province (Belgium). In this study, we reported the recent levels of cadmium and mercury in urine, some organochlorine pesticides and polychlorinated biphenyls (PCBs) in serum, and their relations to demographic characteristics, lifestyle behaviors and dietary habits. The median urinary levels of mercury and cadmium were 0.81 µg/l and <0.5µg/l respectively. The mercury levels were higher in participants having at least 3 dental amalgams, and consuming sea fish more than once a week. Although our mercury levels in most participants were lower than some health-based guidelines, they were higher than in our neighboring countries where ban or restrictions on the dental amalgams use were implemented. Urinary cadmium levels in current smokers were significantly higher than former or never smokers, as well as non-smokers for passively exposed vs non-exposed ones. Median PCB-153 and -180 serum levels were 53.8 and 41.1 ng/g lipid respectively, but PCB-138 was below the limit of quantification of 0.15 µg/l in 49% of the samples. Among the organochlorine pesticides, 4,4’-dichlorodiphenyldichloroethylene (4,4’-DDE), beta-hexachlorohexane and hexachlorobenzene were positively detected respectively in 48%, 49% and 37% of the serum samples. Eventhough, a dramatic decrease in organochlorines levels was observed, at least 1 pesticide or PCB was detected in 96% of our population, and more than 50% of our samples were contaminated by 4 or more organochlorines. Age, body mass index, and breastfeeding duration were the most predictive determinants of pesticide or PCB serum concentrations, but not dietary habits

Acidification is not involved in the early inhibition of Staphylococcus aureus growth by Lactococcus lactis in milk

Seventy-five Lactococcus lactis strains were screened for their inhibitory effect on Staphylococcus aureus growth in milk. Most lactococcal strains had a strong antagonistic effect. Characterization of this effect showed that acidification was not involved in the inhibition observed within the first 24 h of mixed culture. Alternate effects such as bacteriocin- or hydrogen peroxide-production were eliminated. These results question some generally accepted ideas and show that even low acidifying L. lactis strains, widely used in raw milk soft cheeses, can efficiently inhibit S. aureus growth even with initial contamination levels as high as 103 cfum

Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species

International audienceIn mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction

Mécanismes moléculaires de pathogénicité

Mécanismes moléculaires de pathogénicit

Operant conditioning of the visual smooth pursuit in young infants

International audienceSmooth pursuit is a complex behaviour which is not considered as totally functional at birth. The lack of maturation of the visuo-motor systems is generally invoked to explain this phenomenon. However, if this oculomotor response is an operant behaviour, an alternate explanation may be found in the absence of previous confrontation with the environmental contingencies. A first group of young infants were placed in situations in which their oculomotor responses could produce an auditory stimulus. In such situations, young infants are able to improve their pursuit. Music was randomly delivered to a second group. No music was delivered to a third group. For the last two groups no augmentation of the proportion of slow movements was observed. Our main conclusion is that visual tracking has the properties of an operant behaviour and may be enhanced at birth. These results will be discussed within the frameworks of the behavioural discrepancy and of the maturationist hypotheses of the ocular motor control

Transcriptomic Response of Lactococcus lactis in Mixed Culture with Staphylococcus aureus▿ †

The mechanisms of interaction between Lactococcus lactis and the food pathogen Staphylococcus aureus are of crucial importance, as one major role of lactic acid bacteria (LAB) in fermented foods is to inhibit undesirable and pathogenic flora. It was never questioned if the presence of a pathogen can actively modify the gene expression patterns of LAB in a shared environment. In this study, transcriptome and biochemical analyses were combined to assess the dynamic response of L. lactis in a mixed culture with S. aureus. The presence of S. aureus hardly affected the growth of L. lactis but dramatically modified its gene expression profile. The main effect was related to earlier carbon limitation and a concomitantly lower growth rate in the mixed culture due to the consumption of glucose by both species. More specific responses involved diverse cellular functions. Genes associated with amino acid metabolism, ion transport, oxygen response, menaquinone metabolism, and cell surface and phage expression were differentially expressed in the mixed culture. This study led to new insights into possible mechanisms of interaction between L. lactis and S. aureus. Moreover, new and unexpected effects of L. lactis on the virulence of S. aureus were discovered, as described elsewhere (S. Even, C. Charlier, S. Nouaille, N. L. Ben Zakour, M. Cretenet, F. J. Cousin, M. Gautier, M. Cocaign-Bousquet, P. Loubière, and Y. Le Loir, Appl. Environ. Microbiol. 75:4459-4472, 2009)

Gene expression in bovine and mouse cumulus cells in relation with oocyte maturation

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Lactococcus lactis antagonistic potential on Staphylococcus aureus in cheese matrix.

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Microarrays to study Lactococcus lactis and Staphylococcus aureus interactions in cheese matrix

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