Epidemiology of the anal cancer

Le cancer anal est un cancer rare. Sa fréquence est très inférieure à celle des cancers colorectaux puisqu’il ne représente que 3 % de l’ensemble des cancers de la partie basse du tube digestif. Dans la population générale, le cancer de l’anus est plus fréquent chez les femmes que chez les hommes et survient très généralementaprès 60 ans. L’infection à Human Papilloma Virus (HPV) est lefacteur étiologique le plus important avec l’immunodépression quifavorise la transformation maligne des dysplasies anales induitespar l’infection HPV. La population infectée par le VIH, etsingulièrement les patients homosexuels, sont plus à risque de cancer anal que la population générale. En France, l’incidence du cancer anal a été récemment estimée à 1,4/100000 personnes/année (PA) en population générale, à 56,3/100 000 PA dans la population infectée par le VIH et à 95,0/100000 PA dans le sous-groupe des homosexuels masculins VIH+. Un tel sur-risque justifie de mettre en place un dépistage systématique dans la population infectée par le VIH d’autant plus que les combinaisons antirétrovirales semblent sans effet sur le risque d’apparition du cancer anal.Anal cancer is a rare tumor that represents 3 % of all cancer of the lower gastrointestinal tract. In the general population, anal cancer is more frequent in women than in men and usually arises after 60 years. Human Papilloma Virus infection is the most important etiologic factor together with immunodepression that facilitates the malignant transformation of HPV-induced anal dysplasia. In France, the incidence of anal cancer has been estimated to 1.4/100000 person-years (PY) in the general population and to 56.3/100000 PY in HIV-infected patients. This increased risk is in favor of adapting surveillance and screening programs for HIV-infected patients especially since combined antiretroviral therapy does not seem to have any impact on the risk of anal cancer occurrence

Incidence of HIV-related anal cancer remains increased despite long-term combined antiretroviral treatment: results from the french hospital database on HIV.

PURPOSE: To study recent trends in the incidence of anal cancer in HIV-infected patients receiving long-term combined antiretroviral treatment (cART) compared with the general population. PATIENTS AND METHODS: From the French Hospital Database on HIV, we identified 263 cases of invasive anal squamous cell carcinoma confirmed histologically between 1992 and 2008. We compared incidence rates of anal cancer across four calendar periods: 1992-1996 (pre-cART period), 1997-2000 (early cART period), and 2001-2004 and 2005-2008 (recent cART periods). Standardized incidence ratios (SIRs) were calculated by using general population incidence data from the French Network of Cancer Registries. RESULTS: In HIV-infected patients, the hazard ratio (HR) in the cART periods versus the pre-cART period was 2.5 (95% CI, 1.28 to 4.98). No difference was observed across the cART calendar periods (HR, 0.9; 95% CI, 0.6 to 1.3). In 2005-2008, HIV-infected patients compared with the general population had an excess risk of anal cancer, with SIRs of 109.8 (95% CI, 84.6 to 140.3), 49.2 (95% CI, 33.2 to 70.3), and 13.1 (95% CI, 6.8 to 22.8) for men who have sex with men (MSM), other men, and women, respectively. Among patients with CD4 cell counts above 500/μL for at least 2 years, SIRs were 67.5 (95% CI, 41.2 to 104.3) when the CD4 nadir was less than 200/μL for more than 2 years and 24.5 (95% CI, 17.1 to 34.1) when the CD4 nadir was more than 200/μL. CONCLUSION: Relative to that in the general population, the risk of anal cancer in HIV-infected patients is still extremely high, even in patients with high current CD4 cell counts. cART appears to have no preventive effect on anal cancer, particularly in MSM

Olivine formation processes and fluid pathways in subducted serpentinites revealed by in-situ oxygen isotope analysis (Zermatt-Saas, Switzerland)

Dehydration of serpentinites plays a crucial role in mass transfer into the Earth's interior by releasing aqueous fluids and forming new minerals. These minerals, such as metamorphic olivine, can serve as tracers of fluid-related processes. High-pressure (HP) antigorite, metamorphic olivine, and coexisting magnetite in serpentinites from a continuous, km-scale outcrop within the Zermatt-Saas HP ophiolite were analyzed in situ for trace elements and oxygen isotopes to identify differences in the initial serpentinization conditions and to investigate fluid pathways during subduction-related metamorphism. The oxygen isotopic composition, and As and Sb concentrations in antigorite reveal two distinct serpentinization conditions within the studied region: i) high As and Sb (1–25 μg/g and 0.5–5 μg/g, respectively), coupled with δ18O of +6 to +7 ‰, suggesting serpentinization at relatively low temperatures near the seafloor, and ii) low As and Sb (0.03–5 μg/g and ≤ 0.1 μg/g, respectively), coupled with mostly lower δ18O of +4 to +6 ‰, suggesting serpentinization at higher temperatures by interaction with fluids deeper below the seafloor. Olivine produced in situ by the brucite + antigorite dehydration reaction during subduction shows isotopic equilibrium with antigorite, and coexisting magnetite with ∆18OAtg-Ol of +1.5–2.5 ‰ and ∆18OOl-Mt of ∼+3 ‰ at reaction temperature conditions of 550–600 °C. The obtained isotopic signatures of metamorphic olivine with δ18O values of +1 to +2 ‰ and + 4 to +5 ‰ correspond to two different isotopic compositions of the released fluid of +5 to +6 ‰ and + 8 to +9 ‰ at these temperature conditions. This suggests that fluids released from subducted serpentinites may have variable δ18O under forearc conditions. The presence of fluids with variable δ18O can cause olivine in structures associated with fluid flow (e.g., shear bands, shear zones and veins) to be in isotopic equilibrium with magnetite, but in either isotopic equilibrium or disequilibrium with antigorite. Isotopic equilibrium with antigorite is achieved when the fluid responsible for olivine crystallization is internally derived. Isotopic disequilibrium is due to an externally derived fluid released by dehydration of serpentinite with a different isotopic composition than the serpentinite with which the fluid interacts. The restricted occurrence of non-equilibrated olivine only in shear bands and nearly pure Ol-veins indicates channelized fluid flow in subduction zone settings and demonstrates that isotopic disequilibrium can be used as a tracer for fluid infiltration

High‐spatial‐resolution measurements of iron isotopes in pyrites by secondary ion mass spectrometry using the new Hyperion‐II radio‐frequency plasma source

International audienceIron isotopic signatures in pyrites are considered as a good proxy to reconstruct paleoenvironmental and local redox conditions. However, the investigation of micro-pyrites less than 20µm in size has been limited by the evaluable analytical techniques. The development of the new brighter radio-frequency plasma ion source (Hyperion-II source) enhances the spatial resolution by increasing the beam density 10 times compared with the Duoplasmatron source.Here we present high-spatial-resolution measurements of iron isotopes in pyrites using a 3 nA–3 μm primary 16O− beam on two Cameca IMS 1280-HR2 ion microprobe instruments equipped with Hyperion sources at CRPG-IPNT (France) and at SwissSIMS (Switzerland). We tested analytical effects, such as topography and crystal orientation, that could induce analytical biases perceptible through variations of the instrumental mass fractionation (IMF).Results: The δ56Fe reproducibility for the Balmat pyrite standard is ±0.25‰ (2 standard deviations) and the typical individual internal error is ±0.10‰(2 standard errors). The sensitivity on 56Fe+ was 1.2 × 107 cps/nA/ppm or better. Tests on Balmat pyrites revealed that neither the crystal orientation nor channeling effects seem to significantly influence the IMF. Different pyrite standards (Balmat and SpainCR) were used to test the accuracy of the measurements. Indium mounts must be carefully prepared with a sample topography less than 2 μm, which was checked using an interferometric microscope. Such a topography is negligible for introducing change in the IMF. This new source increases the spatial resolution while maintaining the high precision of analyses and the overall stability of the measurements compared with the previous Duoplasmatron source.Conclusions: A reliable method was developed for performing accurate and highresolution measurements of micrometric pyrites. The investigation of sedimentary micro-pyrites will improve our understanding of the processes and environmental conditions during pyrite precipitation, including the contribution of primary (microbial activities or abiotic reactions) and secondary (diagenesis and/or hydrothermal fluid circulation) signatures

Light interception in experimental forests affected by tree diversity and structural complexity of dominant canopy

Biodiversity affects ecosystem functioning in forests by, for example, enhancing growth and altering the forest structure towards greater complexity with cascading effects on other processes and trophic levels. Complexity in forest canopy could enhance light interception and form a link between diversity and productivity in polyculture forests, but the effect of canopy structure on light interception is rarely directly measured. We modelled the canopy surface structure of a tree diversity experiment by photographing it using unmanned aerial vehicle (UAV) and combining the photos into a digital elevation model with photogrammetry tools. We analysed the effects of tree diversity and functional diversity on canopy structural complexity and light interception with a structural equation model. Our results show that: a) increased structural complexity of the canopy reduces light interception, whereas b) tree diversity increases the structural complexity of the canopy, and has a dual impact on light interception. Tree diversity decreased light interception through the structural complexity of the canopy but increased it probably through canopy packing and crown complementarity. However, the effects of both tree diversity and structural complexity of canopy were smaller than the effect of the functional identities of the tree species, especially the differences between deciduous and evergreen trees. We conclude that more complexity in canopy structure can be gained through increased tree diversity, but complex canopy structure does not increase light interception in young forests.Peer reviewe

Surface Analysis by Secondary Ion Mass Spectrometry (SIMS): Principles and Applications from Swiss laboratories

Secondary Ion Mass Spectrometry (SIMS) extracts chemical, elemental, or isotopic information about a localized area of a solid target by performing mass spectrometry on secondary ions sputtered from its surface by the impact of a beam of charged particles. This primary beam sputters ionized atoms and small molecules (as well as many neutral particles) from the upper few nanometers of the sample surface. The physical basis of SIMS has been applied to a large range of applications utilizing instruments optimized with different types of mass analyzer, either dynamic SIMS with a double focusing mass spectrometer or static SIMS with a Time of Flight (TOF) analyzer. Here, we present a short review of the principles and major applications of three different SIMS instruments located in Switzerland

Grain scale processes recorded by oxygen isotopes in olivine-hosted melt inclusions from two MORB samples

International audienceAlthough olivine-hosted melt inclusions from mid ocean ridge basalts (MORB) are commonly used as a proxy formantle composition, these melt inclusions generally show larger elemental and isotopic compositional variationthan their host lavas and the origin of these heterogeneities remains disputed. Here we present oxygen isotopedata from melt inclusions hosted in olivine from two samples from the Mid-Atlantic ridge. Melt inclusions fromdifferent crystals within the same sample show>2.5‰ δ18O variation within each sample, which is nearly eighttimes the analytical error of 0.3‰ (2 standard deviations) and five times the δ18O range in unaltered MORB.Measured δ18O in melt inclusions do not correlate with common magmatic tracers, and δ18O measured in thehost olivines suggest a maximum of 1‰ δ18O source heterogeneity. Less than half of the melt inclusions fromeach sample are in equilibrium with their host crystals; the remaining melt inclusions have either lower or higherolivine-melt oxygen isotope partition coefficients compared to the theoretical equilibrium values. Here wediscuss several potential processes that could contribute to these observations, but none satisfactorily explain theolivine-melt inclusion oxygen disequilibrium that we observe in these samples. Nevertheless, it seems clear thatthe variability of δ18O in melt inclusion from two MORB samples do not record only common magmatic process(es), but rather a localized grain scale process. Any δ18O variation in melt inclusions should thus be interpretedwith caution

A modern scleractinian coral with a two-component calcite–aragonite skeleton

Until now, all of the ca. 1,800 known modern scleractinian coral species were thought to produce skeletons exclusively of aragonite. Asymbiotic Paraconotrochus antarcticus living in the Southern Ocean is the first example of an extant scleractinian that forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite. This discovery adds support to the notion that the coral skeletal formation process is strongly biologically controlled. Mitophylogenomic analysis shows that P. antarcticus represents an ancient scleractinian clade, suggesting that skeletal mineralogy/polymorph of a taxon, once established, is a trait conserved throughout the evolution of that clade.One of the most conserved traits in the evolution of biomineralizing organisms is the taxon-specific selection of skeletal minerals. All modern scleractinian corals are thought to produce skeletons exclusively of the calcium-carbonate polymorph aragonite. Despite strong fluctuations in ocean chemistry (notably the Mg/Ca ratio), this feature is believed to be conserved throughout the coral fossil record, spanning more than 240 million years. Only one example, the Cretaceous scleractinian coral Coelosmilia (ca. 70 to 65 Ma), is thought to have produced a calcitic skeleton. Here, we report that the modern asymbiotic scleractinian coral Paraconotrochus antarcticus living in the Southern Ocean forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite. P. antarcticus and Cretaceous Coelosmilia skeletons share a unique microstructure indicating a close phylogenetic relationship, consistent with the early divergence of P. antarcticus within the Vacatina (i.e., Robusta) clade, estimated to have occurred in the Mesozoic (ca. 116 Mya). Scleractinian corals thus join the group of marine organisms capable of forming bimineralic structures, which requires a highly controlled biomineralization mechanism; this capability dates back at least 100 My. Due to its relatively prolonged isolation, the Southern Ocean stands out as a repository for extant marine organisms with ancient traits.Mitogenome sequences data have been deposited in GenBank (MT409109). All other study data are included in the article text and supporting information

Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit

Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ18O and Mg/Ca) records for the last 1800 kyr from the shallow (487 m) Inner Sea drift deposits of the Maldives archipelago in the equatorial Indian Ocean. Considering the diagenetic susceptibility of these proxies, in carbonate-rich environments, we assess the integrity of a suite of commonly used planktonic and benthic foraminifera geochemical datasets (Globigerinoides ruber (white), Globigerinita glutinata (with bulla), Pulleniatina obliquiloculata (with cortex) and Cibicides mabahethi) and their use for future paleoceanographic reconstructions. Using a combination of spot Secondary Ion Mass Spectrometer, Electron Probe Micro-Analyzer and Scanning Electron Microscope image data, it is evident that authigenic overgrowths are present on both the external and internal test (shell) surfaces, yet the degree down-core as well as the associated bias is shown to be variable across the investigated species and proxies. Given the elevated authigenic overgrowth Mg/Ca (∼12–22 mmol/mol) and δ18O values (closer to the benthic isotopic compositions) the whole-test planktonic G. ruber (w) geochemical records are notably impacted beyond ∼627.4 ka (24.7 mcd). Yet, considering the setting (i.e. bottom water location) for overgrowth formation, the benthic foraminifera δ18O record is markedly less impacted with only minor diagenetic bias beyond ∼790.0 ka (28.7 mcd). Even though only the top of the G. ruber (w) and C. mabahethi records (whole-test data) would be suitable for paleo-reconstructions of absolute values (i.e. sea surface temperature, salinity, seawater δ18O), the long-term cycles, while dampened, appear to be preserved. Furthermore, planktonic species with thicker-tests (i.e. P. obliquiloculata (w/c)) might be better suited, in comparison to thinner-test counter-parts (i.e. G. glutinata (w/b), G. ruber (w)), for traditional whole- test geochemical studies in shallow, carbonate-rich environments. A thicker test equates to a smaller overall bias from the authigenic overgrowth. Overall, if the diagenetic impact is constrained, as done in this study, these types of diagenetically altered geochemical records can still significantly contribute to studies relating to past tropical seawater temperatures, latitudinal scale ocean current shifts and South Asian Monsoon dynamics

Pervasive Eclogitization Due to Brittle Deformation and Rehydration of Subducted Basement: Effects on Continental Recycling?

The buoyancy of continental crust opposes its subduction to mantle depths, except where mineral reactions substantially increase rock density. Sluggish kinetics limit such densification, especially in dry rocks, unless deformation and hydrous fluids intervene. Here we document how hydrous fluids in the subduction channel invaded lower crustal granulites at 50–60 km depth through a dense network of probably seismically induced fractures. We combine analyses of textures and mineral composition with thermodynamic modeling to reconstruct repeated stages of interaction, with pulses of high‐pressure (HP) fluid at 650–670°C, rehydrating the initially dry rocks to micaschists. SIMS oxygen isotopic data of quartz indicate fluids of crustal composition. HP growth rims in allanite and zircon show uniform U‐Th‐Pb ages of ∼65 Ma and indicate that hydration occurred during subduction, at eclogite facies conditions. Based on this case study in the Sesia Zone (Western Italian Alps), we conclude that continental crust, and in particular deep basement fragments, during subduction can behave as substantial fluid sinks, not sources. Density modeling indicates a bifurcation in continental recycling: Chiefly mafic crust, once it is eclogitized to >60%, are prone to end up in a subduction graveyard, such as is tomographically evident beneath the Alps at ∼550 km depth. By contrast, dominantly felsic HP fragments and mafic granulites remain positively buoyant and tend be incorporated into an orogen and be exhumed with it. Felsic and intermediate lithotypes remain positively buoyant even where deformation and fluid percolation allowed them to equilibrate at HP