The sheepshead minnow Cyprinodon variegatus as a marine vertebrate model for investigating endocrine disrupting effects of triclosan

Poster (2012)

Zebrafish (Danio rerio) has been a prominent model in toxicology. This freshwater species present many advantages both in identifying endpoints of toxicity and in elucidating mechanisms of toxicity ... [more ▼]

Zebrafish (Danio rerio) has been a prominent model in toxicology. This freshwater species present many advantages both in identifying endpoints of toxicity and in elucidating mechanisms of toxicity. However, marine toxicologists lack such omnipotent model displaying similar advantages to zebrafish: small size, rapid breeding, and easy maintenance. We propose here the use of the sheepshead minnow Cyprinodon variegatus to define thyroid-disrupting effects of triclosan during pre-hatching development. Three females and two males were placed in each of the three breeding chambers designed for this experiment. More than 300 eggs were collected over three days and maintained in seawater with triclosan concentrations at 0, 100 ng.L-1, and 100 µg.L-1. Exposure of larvae to triclosan lasted until hatching. After hatching (six days post-spawning), 5 larvae per condition were placed in Bouin’s fixative for brain and thyroid histology. Length and body mass were measured. The body was frozen at -80oC to determine muscle thyroid hormone levels (T3 and T4), using radio-immunoassay techniques. Hatching success, in vivo observations, gross observation, thyroid hormone levels, histology will be determined and discussed in the framework of whether or not triclosan may alter thyroid metabolism during pre-hatching period of the sheepshead minnow. [less ▲]

Shell cross-linked stimuli-responsive micelles as vehicles for biomedical applications

Conference (2012, November 16)

Shell Model Potential from a Relativistic Hartree Fock Approach

(1980)

The shell spectrum of BD- 14° 1971 (PGG 1985) in 1947

in Annales d'astrophysique (1950), 13(2), 134-145

Boss 1985 a révélé en fin 1947, un spectre entièrement différent de ce qui avait été observé précédemment. La région ultraviolette est caractérisée par d'intenses raies d'absorption du genre de celles que ... [more ▼]

Boss 1985 a révélé en fin 1947, un spectre entièrement différent de ce qui avait été observé précédemment. La région ultraviolette est caractérisée par d'intenses raies d'absorption du genre de celles que l'on observe dans les étoiles à atmosphère étendue (table I). Les raies d'émission de Fe II, [Fe II] et [Ni II] sont restées à peu près les mêmes que précédemment (table 2). Le spectre ultraviolet est comparé à ceux d'étoiles très étendue. L'analogie de B 1985 et de VV Cephei est discutée. De nouvelles observations tant photométriques que spectroscopiques sont désirables. [less ▲]

Shellfish, a dangerous food?

in Annales de Médecine Vétérinaire (2003), 147(6, DEC-JAN), 413-422

Sea products are consumed worldwide. Seafood, especially shellfish, is consumed crude or not well cooked therefore they are risky for the development of foodborne diseases. Moreover, these animals filter ... [more ▼]

Sea products are consumed worldwide. Seafood, especially shellfish, is consumed crude or not well cooked therefore they are risky for the development of foodborne diseases. Moreover, these animals filter water and concentrate the microorganisms and the toxins. Risks are multiple : bacteria (Clostridium, Vibrio), viruses (norovirus, hepatitis A) and the biotoxins (paralytic, neurotoxic, diarrhoeic and amnesic) produced by phytoplankton. The European regulation 91/492/EC indicates the microbiological and toxicological criteria for the sale of the shellfish. Nevertheless, in the absence of good diagnosis methods, the viruses were omitted in this regulation. But it is a major cause of toxi-infection due to shellfish consumption. The large number of outbreaks worldwide due to the ingestion of seafood indicates that these ones must be carefully controlled. Therefore, we need powerful diagnosis tools. The aim of this review is to describe the major biological risks (bacteria, viruses, biotoxins) for the human health linked to the consumption of sea food. [less ▲]

Shemin Pathway and Peroxidase Deficiency in a Fully Habituated and Fully Heterotrophic Non-Organogenic Sugarbeet Callus: An Adaptative Strategy or the Consequence of Modified Hormonal Balances and Sensitivities in These Cancerous Cells? A Review an

in Cell Proliferation (1999), 32(5), 249-70

There are many arguments for considering a specific fully habituated (auxin and cytokinin-independent) and fully heterotrophic non-organogenic (HNO) sugarbeet callus cell line as terminating a neoplastic ... [more ▼]

There are many arguments for considering a specific fully habituated (auxin and cytokinin-independent) and fully heterotrophic non-organogenic (HNO) sugarbeet callus cell line as terminating a neoplastic progression, and thus to be made of cancerous cells. The similarities with animal tumour and cancer cells are recalled. All types of habituated tissues examined in the literature share at least three common biochemical characteristics: low apparent peroxidase activity, high content of polyamines (PAs) and low production of ethylene. However, results concerning their auxin and cytokinin levels are not consistent. Peroxidase synthesis in the achlorophyllous HNO callus appears to arise from aminolevulinic acid (ALA) synthesis through the Shemin pathway, commonly used by animals and fungi. This pathway is limited by disturbed nitrogen metabolism that diverts glutamate (directly used for ALA synthesis in green higher plants) from the Kreb's cycle into PA synthesis. There is no argument to suggest that the low ethylene production is caused by a competition with PAs for their common precursor, S-adenosylmethionine. The results we report here indicate modified anabolic and catabolic pathways of auxins and cytokinins but also the possibilities of unusual compounds playing similar roles (dehydrodiconiferyl alcohol glucosides, for instance). A higher turnover of PAs is shown in the HNO callus, which could suggest a role for H2O2 and gamma-aminobutyric acid, products or intermediates in the PA catabolic pathway, as secondary messengers. The habituated cells retain some sensitivity towards exogenous auxins and cytokinins. Their increased sensitivity to PAs and ethylene suggests modified hormonal balances for the control of these actively dividing cells. [less ▲]

Shielding efficiency and E(J) characteristics measured on large melt cast Bi-2212 hollow cylinders in axial magnetic fields

in Superconductor Science and Technology (2010), 23

We show that tubes of melt cast Bi-2212 used as current leads for LTS magnets can also act as efficient magnetic shields. The magnetic screening properties under an axial DC magnetic field are ... [more ▼]

We show that tubes of melt cast Bi-2212 used as current leads for LTS magnets can also act as efficient magnetic shields. The magnetic screening properties under an axial DC magnetic field are characterized at several temperatures below the liquid nitrogen temperature (77 K). Two main shielding properties are studied and compared with those of Bi-2223, a material that has been considered in the past for bulk magnetic shields. The first property is related to the maximum magnetic flux density that can be screened, Blim; it is defined as the applied magnetic flux density below which the field attenuation measured at the centre of the shield exceeds 1000. For a cylinder of Bi-2212 with a wall thickness of 5 mm and a large ratio of length over radius, Blim is evaluated to 1 T at T = 10 K. This value largely exceeds the Blim value measured at the same temperature on similar tubes of Bi-2223. The second shielding property that is characterized is the dependence of Blim with respect to variations of the sweep rate of the applied field, dBapp/dt. This dependence is interpreted in terms of the power law E = Ec(J/Jc)^n and allows us to determine the exponent n of this E(J) characteristics for Bi-2212. The characterization of the magnetic field relaxation involves very small values of the electric field. This gives us the opportunity to experimentally determine the E(J) law in an unexplored region of small electric fields. Combining these results with transport and AC shielding measurements, we construct a piecewise E(J) law that spans over 8 orders of magnitude of the electric field. [less ▲]

Shifting Towards Environment-Friendly Modes: Profiling Travelers using Q-Methodology

in Proceedings of the 88th Annual Meeting of the Transportation Research Board (DVD-ROM) (2009)

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental ... [more ▼]

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental repercussions. Despite technological advancements, the externalities remain an ecological threat that can not be discarded by policy makers. Therefore, it is essential that policy makers focus on reducing car use and on stimulating the shift towards more environment-friendly transport modes. In this study, Q-methodology is adopted as the technique to segment people, and to ascertain which approaches and determinants matter to medium distance travel. Segmentation is important, as policy measures will be more efficient and effective if they are fine-tuned on specific target groups. The analysis revealed that four discourses preponderate the paradigm of environmentally sustainable transport: travelers who use public transport as a dominant alternative, car-dependent travelers, travelers with a positive perception of using public transport, and travelers with a preference for car use. Concerning rational, economic motives, individuals evaluate travel time reliability as most important. To increase the reliability policy makers should consider the use of separate bus lanes and traffic light manipulation. In addition, public transport can be made even more attractive, when costs of cars are made more variable by road or congestion charging. When the subjective motives are discussed, the differences between the different groups of travelers were more pronounced. Next to increasing the benefits of using public transport, policy makers should also pay attention to removing psycho-social barriers. [less ▲]

Shifts in microbial population fermenting contrasting indigestible carbohydrate sources measured in the intestines of pigs and using an in vitro model of the pig gastro-intestinal tract

in International Scientific Conference on probiotics and prebiotics - IPC 2011 Conference Proceedings (2011, June)

Shiga-like toxin production and attaching and effacing activity of Escherichia coli associated with calf diarrhea

in American Journal of Veterinary Research (1987), 48