Global heat flow trends resolved from multiple geological and geophysical proxies

International audienceBecause global coverage of heat flow measurements is still poor in many areas, empirical estimators based on the geology, the thermotectonic age or the velocity structure of the upper mantle have often been used to affect an estimate to regions where such measurements are absent. On the basis of the assumption that heat flow is strongly related to its geodynamic environment, one may integrate multiple proxies derived from a large body of global geo- logical and geophysical data sets assembled during the past decades; these should help to better capture the variety of present-day settings. This idea is illustrated through two simple empirical methods: both of them are based on a set of examples, where heat flow measure- ments are associated with relevant terrestrial observables such as surface heat production, upper-mantle velocity structure, tectono-thermal age, on a 1◦ × 1◦ grid. To a given target point owning a number of observables, the methods associate a heat flow distribution rather than a deterministic value to account for intrinsic variability and uncertainty within a defined geodynamic environment. The 'best combination method' seeks the particular combination of observables that minimizes the dispersion of the heat flow distribution generated from the set of examples. The 'similarity method' attributes a weight to each example depending on its degree of similarity with the target point. The methods are transparent and are able to handle sets of observables that are not available over the whole Earth (e.g. heat production). The resulting trends of the mean heat flow deduced from the two methods do not differ strongly, but the similarity method shows a better accuracy in cross-validation tests. These tests suggest that the selected proxies have the potential to recover at least partly medium- to large-scale features of surface heat flow. The methods depict the main global trends of low heat flow in stable and ancient regions, and thermal high in active orogens and rift zones. Broad thermal anomalies are outlined in the Sahara and in the tectonically active eastern part of Antarctica. The similarity method estimates a continental heat loss of 13.6 ± 0.8 TW (2σ uncertainty), which is consistent with previous estimates

Anti-TNF therapy in refractory pouchitis and Crohn's disease-like complications of the pouch after ileal pouch-anal anastomosis following colectomy for ulcerative colitis: a systematic review and meta-analysis

International audienceBackground: Pouchitis and secondary Crohn's disease (CD)-like complication of the pouch are the most common complications after ileal pouch-anal anastomosis following colectomy for ulcerative colitis. Data about the effectiveness of anti-TNF agents in these two entities remains sparse. We aimed to perform a systematic review and meta-analysis to evaluate the efficacy of anti-TNF therapy in differentiating patients with chronic refractory pouchitis and CD-like complications. Methods: Systematic literature search was performed in MEDLINE and from international meetings abstracts. The search process, selection of manuscripts, and data extraction were performed independently by two physicians according to PRISMA statements. Prevalence and 95% confidence interval (CI) were estimated using random-effects models assuming between and within study variability. Statistical heterogeneity between results was assessed by examining forest plots, CIand using I2 and sensitivity analyses were conducted. CD-like complications of the pouch were defined as the presence of non-anastomotic fistula and/or non-anastomotic stenosis and/or prepouch ileitis. Chronic refractory pouchitis was defined as inflammation limited to the pouch. The short term and the long term responses were evaluated at 8 weeks and 12 months, respectively. Results: We identified 21 articles and three abstracts including 313 patients treated either with infliximab (IFX) (n=194) or adalimumab (ADA) (n=119) for inflammatory complications of the pouch. The rate of complete response (CR) after anti-TNF induction therapy for inflammatory complications of the pouch was 0.51 (95% CI [0.39–0.64]; I2=0.56). The rate of short-term CR was 0.57 (95% CI [0.38–0.75]; I2=0.36) for IFX-treated patients compared to 0.38 (95% CI [0.08–0.72]; I2=0.50) for ADA-treated patients (p=0.20). The long-term rate of CR in patients treated with anti-TNF therapy was 0.52 (95% CI [0.39–0.65]; I2=0.59), with 0.59 (95% CI [0.45–0.72]; I2=0.30) for IFX-treated patients compared to 0.30 (95% CI [0.15–0.46]; I2=0.00) for ADA-treated patients (p=0.19). The rate of CR after anti-TNF induction therapy seemed to be higher for CD-like complications of the pouch 0.64 (95% CI [0.5–0.77]; I2=0.18), compared to refractory pouchitis 0.10 (95% CI [0.08–0.35]; I2=0.00) (p=0.06). The rate of long-term CR in patients treated with anti-TNF was 0.57 (95% CI [0.43–0.71]; I2=0.32) for CD-like complications of the pouch compared to refractory pouchitis 0.37 (95% CI [0.14–0.62]; I2=0.47) (p=0.57). Conclusions: Despite wide heterogeneity of the data, anti-TNF agents have a clear trend to have higher and faster efficacy in CD-like complications of the pouch compared to refractory pouchitis, highlighting the need to differentiate these two entities in clinical practice

Endoscopic factors influencing fecal calprotectin value in crohn's disease

International audienceBackground and Aims: Fecal calprotectin [fcal] is a biomarker of Crohn's disease [CD] endoscopic activity. Identifying the endoscopic situations in which fcal is less reliable remains unexplored. We aimed to determine the endoscopic factors influencing fcal level in CD. Methods: Overall, 53 CD patients consecutively and prospectively underwent colonoscopy, with CD Endoscopic Index of Severity [CDEIS] calculation and stool collection. Fcal was measured using a quantitative immunochromatographic test. Correlation analysis was done with Pearson statistics. Results: Fcal was correlated with CDEIS [0.66, p = 200 mu g/g was highly sensitive [0.86] to detect SU or DU. Conclusions: Fcal is a very reliable biomarker to detect endoscopic ulcerations in CD. We suggest repeating measurement in case of intermediary results [200-400 mu g/g] in daily practice. Fcal level is mostly influenced by the presence of CD lesions [even non-ulcerated], in a depth-related manner and by the affected surface

Heat-flow and hydrothermal circulation at the ocean-continent transition of the eastern gulf of Aden

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