The mechanisms of action of interleukin-1 on rabbit intestinal epithelial cells.

Interleukin-1 (IL-1) is an inflammatory mediator that increases Cl- secretion in intestinal epithelial cells. To identify the signal transduction pathway(s) involved in IL-1's action, cells were treated with IL-1 and the levels of cyclooxygenase (COX) enzymes, prostaglandin E2 (PGE2) and phospholipase A2-activating protein (PLAP), and the activity of phospholipase A2 (PLA2) were measured. IL-1 caused concentration- and time-dependent increases in the levels of PLA2 activity, and/or in the levels of PLAP, COX-2 and PGE2. The IL-induced increase in PGE2 levels was biphasic, with the first peak due to the increase in PLAP levels, and the second peak due to the increase in COX-2 levels. This increase in PGE2 levels may provide a mechanism for acute and chronic inflammation in the intestine

Diversité spécifique de la macrofaune benthique dans la côte ouest de la baie de Tunis et la côte de l'île de Djerba (sud-ouest de la Méditerranée)

In this study, 21 stations were sampled, 11 in the Djerba island coast and 10 in the western coast of Tunis bay. Then, samples were sifted on a square mesh of 1 mm a side, and the animals collected were identified and counted. Lacking an efficient single index suitable for application in all situations, several traditional nonparametric indices of biodiversity were selected, calculated and discussed. Results show that the community composition is totally different in the two studied sites, and, within each site, several species are common, butthey exchange the leader ranks from one station to another. For biodiversity measurement and since results show varying values depending on indices at several stations, an arithmetic mean index was calculated at each station on the basis of the most similar indices. It shows that, overall, the biodiversity is significantly higher in Tunis bay coast than in Djerba coast. These results are more reliable considering the real environmental /anthropogenic constraints imposed on both sites. Indeed, Djerba coast is subject, these last decades, to strong industrial, urban and fishing activities, causing significant regression of benthic habitats, which can led to a reduction of the biodiversity.Dans cette étude, 21 stations ont été échantillonnées, 11 dans la côte de l'île de Djerba et 10 dans la côte ouest de la baie de Tunis. Ensuite, les échantillons ont été tamisés sur une maille carrée de 1 mm de côté, et les animaux capturés ont été identifiés et comptés. Faute d'un indice unique efficace et adapté à toutes les situations, plusieurs indices traditionnels de biodiversité ont été choisis, calculés et discutés. Les résultats montrent que la composition de la communauté est totalement différente dans les deux sites étudiés, et, à chaque site, plusieurs espèces sont communes, mais ils se substituent aux places des leaders d'une station à l’autre. Pour la mesure de la biodiversité et étant donné la grande différence dans les valeurs enregistrées par les indices retenus, une moyenne arithmétique a été calculée à chaque station sur la base des indices les plus cohérents. Elle montre que, globalement, la biodiversité est nettement plus élevée dans la baie de Tunis par rapport à la côte de Djerba. Ces résultats semblent être plus fiables tenant en compte les contraintes réelles environnementales et anthropiques imposées aux deux sites. En effet, la côte de Djerba est l'objet, ces dernières décennies, à de fortes activités urbaines et de pêche industrielle, entraînant une régression significative des habitats benthiques, ce qui peut conduire à la réduction de la biodiversité

IL-1 stimulates ceramide accumulation without inducing apoptosis in intestinal epithelial cells.

BACKGROUND: In inflammatory bowel disease (IBD), cytokine levels (such as interleukin-1 (IL-1)) are elevated. We have shown previously that IL-1 activates phospholipid signaling pathways in intestinal epithelial cells (EEC), leading to increased ceramide levels. AIM: To determine whether ceramide induces apoptosis in IEC. METHODS: Apoptosis was evaluated by annexin-V binding or Hoechst nuclear staining. Levels of bcl-2, bcl-x, bax, p53 and p21 were determined by Western blotting, and celi cycle analysis was determined by flow cytometry. RESULTS: IL-1 increased ceramide accumulation in a time-dependent and concentration-dependent manner with a peak response at 4 h, with [IL-1] = 30 ng/ml. Neither IL-1 nor ceramide induced apoptosis in EEC, but they increased bcl-2 levels and decreased bax and p21 levels without affecting bcl-x and p53 levels. They also caused a slight but significant increase in the G2/M phase. These data suggest a role for ceramide in IBD and suggest a possible mechanism for the enhanced tumorigenic activity in IBD patients

Transfer and accumulation of lead, zinc, cadmium and copper in plants growing in abandoned mining-district area

The analysis of the Jebel Hallouf-Sidi Bouaouane mining-district soil has shown that the surface horizons are strongly contaminated by heavy metals, especially during floods or in lee-side areas. The contents of metallic-trace elements (MTE), in the soil and two cultivated plant species, have been determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). The results show that the concentration of metals in the soil are up to 39 g. kg-1, 6.3 g. kg-1, 56 mg. kg-1 and 131 mg. kg-1, for lead (Pb), zinc (Zn), cadmium (Cd) and copper (Cu), respectively. The chemical analysis of plants: broad beans [Vicia faba (L.)] and barley [Hordeum vulgare (L.)], sampled inside the mining district, show that the roots and the upper part (leaves and stem) are enriched for Pb (up to 508 and 220 mg.kg-1, respectively), Cd (up to 8 and 5 mg.kg-1, respectively), and Zn (up to 491 and 468 mg.kg-1, respectively) when compared with similar species collected far from the contaminated site (up to 9.6 and 0.8 mg.kg-1 for Pb, up to 0.04 and 0.04 mg.kg-1 for Cd, up to 44 and 15 mg.kg-1 for Zn, respectively). Statistically, the concentration of MTE in the soils and plants of the mining area is significantly different from the concentrations of the same elements in the soils and plants of the control ones (p < 0.01). This is expressed by a strong Enrichment Coefficient (EC), which is given by the ratio between the concentration of the metal in the contaminated plant and the concentration of the same element in the similar control one. The results (up to 405, 342 and 32, respectively), indicate that the contamination has reached the first link of the food chain. However, the calculation of the translocation factor (TF), deduced from the ratio between the concentration of the metal in the outer part of the plant and the concentration of the same element in the roots, shows that, the broad beans accumulates metals in the roots (TF < 1); whereas for barley, metals are fairly distributed between the roots and the outer part (TF ≈ 1). These results suggest that the cultivated areas inside the mining district constitute a serious source of contamination of the food chain. Therefore, actions have to be taken in order to remedy this problem.Key words: MTE, contamination, transfer, soil, plant

Disentangling the heterogeneous income elasticity and dynamics of health expenditure.

In this article, we empirically study the impact of per capita income on health-care expenditure and its dynamics over time in a sample of 14 OECD countries for the period 1971 to 2009. A simple model, built upon one developed by Newhouse (1977), suggests that health care is a necessity in the short run but it cannot be rejected to be a luxury good in the long run. Our findings provide strong empirical evidence that a year’s health expenditure is conditioned by the previous one. Interestingly, our results reveal increasing income inelasticity over time along with huge heterogeneity across countries. Finally, this article supports the hypothesis of conditional convergence in health-care spending among countries. In designing policies which facilitate the sustainability of national health systems, we emphasize that ceteris paribus the greater the participation of public health, the lower the growth rate of health spending. High share of children and elderly over working age population opposite influences. We also provide evidence that technological progress could reduce the long-run income elasticity for health care, which in turn threaten the sustainability of health-care systems

A study of patent thickets

Report analysing whether entry of UK enterprises into patenting in a technology area is affected by patent thickets in the technology area

Molecular architecture and activation of the insecticidal protein Vip3Aa from Bacillus thuringiensis

Bacillus thuringiensis Vip3 (Vegetative Insecticidal Protein 3) toxins are widely used in biotech crops to control Lepidopteran pests. These proteins are produced as inactive protoxins that need to be activated by midgut proteases to trigger cell death. However, little is known about their three-dimensional organization and activation mechanism at the molecular level. Here, we have determined the structures of the protoxin and the protease-activated state of Vip3Aa at 2.9 Å using cryo-electron microscopy. The reconstructions show that the protoxin assembles into a pyramid-shaped tetramer with the C-terminal domains exposed to the solvent and the N-terminal region folded into a spring-loaded apex that, after protease activation, drastically remodels into an extended needle by a mechanism akin to that of influenza haemagglutinin. These results provide the molecular basis for Vip3 activation and function, and serves as a strong foundation for the development of more efficient insecticidal proteins