Apc mutation induces resistance of colonic cells to lipoperoxide-triggered apoptosis induced by faecal water from haem-fed rats

Recent epidemiological studies suggest that high meat intake is associated with promotion of colon cancer linked to haem-iron intake. We previously reported that dietary haem, in the form of either haemoglobin or meat, promotes precancerous lesions in the colon of rats given a low-calcium diet. The mechanism of promotion by haem is not known, but is associated with increased lipid peroxidation in faecal water and strong cytotoxic activity of faecal water on a cancerous mouse colonic epithelial cell line. To better understand the involvement of faecal water components of haem-fed rats in colon cancer promotion, we explored the effect of faecal water on normal (Apc +/+) or premalignant cells (Apc Min/+). Further, we tested if this effect was correlated to lipoperoxidation and 4-hydroxynonenal (HNE). We show here for the first time that heterozygote Apc mutation represents a strong selective advantage, via resistance to apoptosis induction (caspase 3 pathway), for colonic cells exposed to a haem-iron induced lipoperoxidation. The fact that HNE treatment of the cells provoked the same effects as the faecal water of rats fed the haem-rich diet suggests that this compound triggers apoptosis in those cells. We propose that this mechanism could be involved in the promotion of colon carcinogenesis by haem in vivo

Stable isotopes reveal dietary shifts associated with social change in Hellenistic, Roman and Late Antique Knossos

Knossos was an important city on Crete and within Mediterranean networks in terms of trade and political status, though its status differed throughout the Hellenistic, Roman and Late Antique periods. This paper uses stable carbon and nitrogen isotope analysis to consider whether people at Knossos had differential diets due to the social, political, cultural, and economic changes across this time frame, factoring in age, sex and social status. Samples of human bone were selected to represent this range of time periods and variables. In this initial study, a small but insignificant increase in δ13C values was observed between the Hellenistic and Roman periods and there was a significant increase in δ15N values for the Late Antique period. No relationship between δ13C or δ15N and age was observed and while the female and male means were similar, the females had wider ranging values. No significant differences were detected by social status as represented by tomb type but there were small sample sizes for several of the tomb types. The results indicated a C3 terrestrial diet with meat or other animal products included for most individuals. The slight increase in δ13C values in the Roman period may represent either the introduction of a small amount of C4 plant or marine food, or very low trophic level marine foods into some Roman diets. The higher δ13C and, in particular, δ15N values observed in the Late Antique samples, suggests an increased consumption of seafood, potentially linked to Christian dietary practices or advances in fishing technologies and preservation techniques. The wider spread values of females compared to males, indicating a more varied diet, could have resulted from differential participation in religious institutions connected to food or may have been caused by greater nutritional stress in females in relation to pregnancy and reproductive issues. This study does not show a pattern of higher animal protein consumption in times of economic and cultural growth and prosperity but differences were detected between the different time periods in connection with the concurrent socio-economic changes

Estimation de probabilités par un algorithme génétique adapté.

International audienceIn the insurance comparison domain, data constantly evolve, implying some difficulties to directly exploit them. Indeed, most of the classical learning methods require data descriptors equal to both learning and test samples. To answer business expectations, online forms where data come from are regularly modified. This constant modification of features and data descriptors makes statistical analysis more complex. A first work with statistical methods has been realized. This method relies on likelihood and models selection with the Bayesian information criterion. Unfortunately, this method is very expensive in computation time. Moreover, with this method, all models should be exhaustively compared, what is materially unattainable, so the search space is limited to a specific models family. In this work, we propose to use a genetic algorithm (GA) specifically adapted to overcome the statistical method defaults and shows its performances on real datasets provided by the company MeilleureAssur-ance.com

Estimation de probabilités par algorithme génétique

National audienc

Diagenesis in salt dome roof strata: barite - calcite assemblage in Jebel Madar, Oman

Halokinesis causes a dynamic structural evolution with the development of faults and fractures, which can act as either preferential fluid pathways or barriers. Reconstructing reactive fluid flow in salt dome settings remains a challenge. This contribution presents for the first time a spatial distribution map of diagenetic phases in a salt dome in northern Oman. Our study establishes a clear link between structural evolution and fluid flow leading to the formation of diagenetic products (barite and calcite) in the salt dome roof strata. Extensive formation of diagenetic products occurs along NNE-SSW to NE-SW faults and fractures, which initiated during the Santonian (Late Cretaceous) and were reactivated in the Miocene, but not along the E-W fault, which was generated during Early Paleocene time. We propose that the diagenetic products formed by mixing of a warm (100 °C) saline (17 wt% NaCl eq.) 87Sr enriched (87Sr/86Sr: 0.71023) fluid with colder (35 °C) meteoric fluid during Miocene to Pleistocene. The stable sulphur and strontium isotope composition and fluid inclusion data indicate that a saline fluid, with sulfate source derived from the Ara Group evaporite and Haima Supergroup layers, is the source for barite formation at about 100 °C, predominantly at fault conjunctions and minor faults away from the main graben structure in the dome. In the Miocene, the saline fluid probably ascended along a halokinesis-related fault due to fluid overpressure (due to the rising salt and impermeable layers in the overlying stratigraphic sequence), and triggered the formation of barite due mixing with barium-rich fluids, accompanied by a drop in temperature. Subsequently, evolving salt doming with associated fault activity and erosion of the Jebel allows progressively more input of colder meteoric fluids, which mix with the saline warmer fluid, as derived from stable isotope data measured in the progressively younger barite-associated calcite, fault zone calcite and macro-columnar calcite. The reconstructed mixing model indicates a 50/50 to 90/10 meteoric/saline fluid mixing ratio for the formation of fault zone calcite, and a 10 times higher concentration of carbon in the saline fluid end member compared to the meteoric fluid end member. The presented mixing model of salt-derived fluids with meteoric fluids is suggested to be a general model applicable to structural diagenetic evolution of salt domes world wide

Humid phases on the southwestern Arabian Peninsula are consistent with the last two interglacials

Past environmental and climatic conditions within the Arabian Peninsula are key to understanding the setting for hominin dispersal across the Saharo-Arabian dryland belt. The tufa deposits within the volcanic harrats on the southwest coast of Saudi Arabia fill a significant spatial gap in the distribution of palaeoenvironmental records on the west coast of the Arabian Peninsula adjacent to the Red Sea. In the catchment of Wadi Dabsa in the Harrat Al Birk, there are widespread fossil palustrine to shallow-lacustrine tufa deposits with fluvial elements. Several phases of tufa accumulation, separated by fluvial downcutting, are observable within these powerful palaeoenvironmental proxies. U–Th dating of targeted dense, banded tufa facies, yield ages that are stratigraphically consistent at the landscape scale, and indicate that tufa accumulation occurred during distinct humid phases broadly coeval with the last two warm interglacial Marine Isotope Stages (MIS 7 and MIS 5). For the first time this shows humid intervals in southwest Arabia coincident with the southern coast. There is a simlar pattern emerging further north in the Arabian Peninsula, The Sinai and Levant and further on into continental Europe. Furthermore, tufa δ18O ranges from −14.6 to −1.9‰, covering a range similar to those reported for tufa from north African oasis sites and speleothems elsewhere on the Arabian Peninsula and The Levant. The lowest δ18O values are derived from MIS 5e samples, a pattern in agreement with speleothems in Yemen and Oman, and consistent with an isotopic-enabled climate model simulation for this time slice. The δ13C and Sr isotopic compositions of dated tufa samples indicate deposition from shallow-circulating meteoric water, with no geothermal influence. This, along with the δ18O values, suggest a freshwater supply that was a potable water source in this landscape. The δ13C signatures at Wadi Dabsa are more negative than for parts of north Africa, suggesting Wadi Dabsa may have experienced comparatively higher biomass, thicker soils and wetter conditions with lower evaporative losses. This new record of tufa deposition during the middle and late Pleistocene, suggests for the first time that the west coast of Arabia experienced a similar history of humid phases over the past 250 ka as southern Arabia and the Nefud in the northern interior. These regional changes in hydroclimatic regime occur at timescales coincident with hominin dispersals

Lake isotope records of the 8200-year cooling event in western Ireland: Comparison with model simulations

The early Holocene cooling, which occurred around 8200 calendar years before present, was a prominent abrupt event around the north Atlantic region. Here, we investigate the timing, duration, magnitude and regional coherence of the event as expressed in carbonate oxygen-isotope records from three lakes on northwest Europe's Atlantic margin in western Ireland, namely Loch Avolla, Loch Gealáin and Lough Corrib. An abrupt negative oxygen-isotope excursion lasted about 200 years. Comparison of records from three sites suggests that the excursion was primarily the result of a reduction of the oxygen-isotope values of precipitation, which was likely caused by lowered air temperatures, possibly coupled with a change in atmospheric circulation. Comparison of records from two of the lakes (Loch Avolla and Loch Gealáin), which have differing bathymetries, further suggests a reduction in evaporative loss of lake water during the cooling episode. Comparison of climate model experiments with lake-sediment isotope data indicates that effective moisture may have increased along this part of the northeast Atlantic seaboard during the 8200-year climatic event, as lower evaporation compensated for reduced precipitation

Estimation de probabilités par un algorithme génétique adapté.

International audienceIn the insurance comparison domain, data constantly evolve, implying some difficulties to directly exploit them. Indeed, most of the classical learning methods require data descriptors equal to both learning and test samples. To answer business expectations, online forms where data come from are regularly modified. This constant modification of features and data descriptors makes statistical analysis more complex. A first work with statistical methods has been realized. This method relies on likelihood and models selection with the Bayesian information criterion. Unfortunately, this method is very expensive in computation time. Moreover, with this method, all models should be exhaustively compared, what is materially unattainable, so the search space is limited to a specific models family. In this work, we propose to use a genetic algorithm (GA) specifically adapted to overcome the statistical method defaults and shows its performances on real datasets provided by the company MeilleureAssur-ance.com

Appariement de descripteurs évoluant en temps: Application à la comparaison d'assurance en ligne

National audienceIn the web domain, and in particular for insurance comparison, data constantly evolve, implying that it is dicult to directly exploit them. For example, to do a classication, performing standard learning processes require data descriptor equal for both learning and test samples. Indeed, for answering to web surfer expectation, online forms whence data come from are regularly modied. So, features and data descriptors are also regularly modied. In this work, we introduce a process to estimate and understand connections between transformed data descriptors. This estimated matching between descriptors will be a preliminary step before applying later classical learning methods.Dans le domaine du web, et plus particulièrement de la comparaison d'assurance en ligne, les données évoluent constamment ce qui rend leur exploitation difficile. Par exemple, la plupart des méthodes d'apprentissage standards nécessitent des descripteurs de données identiques pour les échantillons d'apprentissage et test. Cependant, afin de répondre aux attentes métier, les formulaires en ligne d'où proviennent les données sont régulièrement modifiés. Cela implique une modification régulière des variables et des descripteurs de données qui complexifie les analyses. Dans ce travail, nous proposons une méthode permettant d'estimer et de comprendre les liens qui se forment lors de la modification des descripteurs de données afin de les apparier. Cette étape est préliminaire à l'application de nombreuses méthodes d'apprentissage ultérieures