New understanding of gluten sensitivity.

Among gluten-related disorders, gluten sensitivity is an emerging entity that is characterized by a wide array of manifestations. In particular, patients complain of IBS-like symptoms and extraintestinal manifestations that occur shortly after the ingestion of gluten. Symptoms improve or disappear when gluten is withdrawn from the diet, and recur if gluten is reintroduced. Laboratory tests are usually unhelpful for diagnosis, although ∼50% of patients are positive for IgG antigliadin antibodies. The natural history of gluten sensitivity is unknown; in particular, it is still to be clarified whether this disorder is permanent or transient and whether it is linked to autoimmunity. The pathogenesis of gluten sensitivity is unclear; data so far demonstrate a predominant activation of innate immune responses. Further research is necessary to establish the main clinicopathological features of gluten sensitivity, thus enabling physicians to improve their management of the increasing number of patients who are sensitive to dietary gluten. © 2012 Macmillan Publishers Limited. All rights reserved

Nutrient trapping in the equatorial Pacific: The ocean circulation solution

International audienceNutrient trapping is a chronic problem found in global carbon cycle models with particle-only remineralization schemes. It is defined as the excess of subsurface nutrient concentrations relative to observations and occurs principally in the eastern equatorial Pacific. Previous studies reduced excess simulated nutrients by increasing the complexity of modeled biogeochemistry, i.e., by adding pools for nutrients (and carbon) either in dissolved organic form or as plankton. Conversely, our study suggests that deficiencies in modeled circulation fields from global coarse-resolution ocean models are mostly responsible. This new interpretation stems from our use of an ocean general circulation model with higher resolution, which offers a more realistic equatorial circulation. We used the same biogeochemical model Hamburg ocean carbon cycle model, version 3, as in some of the previous studies. Our model-predicted distribution of PO43- in the equatorial Pacific agrees reasonably well with the observations both at the surface and in the subsurface. Subsurface PO43- concentrations in our model's eastern equatorial Pacific exceed observations by, at most, 15%, unlike coarser-resolution models. Improvement is due to enhanced meridional resolution (0.5°) near the equator, which allows the model to simulate a vigorous equatorial undercurrent that brings in low-nutrient water from the western basin. Furthermore, the model upwells no nutrient-rich abyssal water into the surface equatorial Pacific. Our results suggest that dissolved organic carbon plays a minor role in the carbon budget of the equatorial Pacific