Subduction zone fluids and arc magmas conducted by lithospheric deformed regions beneath the central Andes.

Dehydration of the oceanic subducting slab promotes the formation of magmatic arcs, intra-slab intermediate-depth seismicity, and hydration of the overlying mantle wedge. However, the complex permeability structure of the overriding plate controls the magma and fluid migration and their accumulation at shallower depths. In this regard, mapping the inner structure of the overriding crust and mantle is crucial to understand the magmatic and hydrological processes in subduction zones. We integrate 3-D P-wave, [Formula: see text], and electrical resistivity tomographic models of the northern Chilean subduction zone to map the magmatic and fluids derived from the subducting oceanic Nazca plate. Results show a continental crust relatively thick (50-65 km) characterized by a lower zone of high [Formula: see text] values (7.2-7.6 km/s), which is interpreted as the presence of plutonic rocks. The mantle lithospheric wedge is weakly hydrated ([Formula: see text] = 1.75-1.8) while the forearc continental crust is traversed by regions of reduced electrical resistivity values ([Formula: see text] [Formula: see text]) interpreted as zones of relatively high permeability/fracturing and fluid content. These regions spatially correlate with upper plate trans-lithospheric deformation zones. Ascending melts accumulate preferentially in the back-arc, whereas hydrothermal systems form trenchward of the volcanic arc. The results highlight the complex permeability structure of the upper South American plate.

Increased bacterial putrescine has no impact on gut morphology and physiology in gnotobiotic adolescent mice.

Gut bacteria influence host anatomy and physiology. It has been proposed that bacterial metabolites including polyamines are responsible for intestinal maturation and mucosal growth. We have hypothesised that bacterially produced polyamines act as trophic factors and thereby influence large intestinal crypt depth and thickness of the different gut layers. For that purpose, germ-free mice were associated with two different microbial consortia. One group was colonised with a simplified human microbiota (SIHUMI). The second group was associated with SIHUMI + Fusobacterium varium (SIHUMI + Fv), which is known to produce high amounts of polyamines. Polyamine concentrations were measured by HPLC and morphological parameters were determined microscopically. Germ-free and conventional mice served as controls. The caecal putrescine concentration of the SIHUMI + Fv was 61.8 µM (47.6-75.5 µM), whereas that of conventional and SIHUMI mice was 28.8 µM (1.3-41.7 µM) and 24.5 µM (16.8-29.1 µM), respectively. The caecal putrescine concentration of germ-free mice was only 0.6 µM (0-1.0 µM). Caecal crypt depth and thickness of the different caecal layers revealed no significant differences between SIHUMI and SIHUMI + Fv mice. However, the crypt depth in the caeca of conventional, SIHUMI and SIHUMI + Fv mice was increased by 48.6% (P<0.001), 39.7% (P<0.001) and 28.5% (P<0.05), respectively, compared to germ-free mice. These findings indicate that increased intestinal putrescine concentrations do not influence gut morphology in our gnotobiotic adolescent mice.

Regulation of interleukin 12 and interleukin 10 expression in vaccinia virus-infected human monocytes and U-937 cell line.

Regulation of IL-12 and IL-10 production in normal human monocytes infected with vaccinia virus (VV) was analysed. IL-12 and IL-10 mRNAs were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and IL-12 and IL-10 protein by ELISA. RT-PCR analysis revealed a marked-up regulation of IL-12 (p40) and IL-10 expression in virally infected cells compared with that from control (non-infected) cells at 24 h post-infection (p.i.). IL-12 transcripts occurred earlier (at 4 h p.i.) than IL-10 mRNA. A significant increase in IL-12 and IL-10 secretion into the medium was caused by the virus, and even a much more pronounced increase in both interleukins expression (mRNAs and proteins) followed LPS or Staphylococcus aureus treatment. Vaccinia virus infection did not alter IL-10 secretion and IL-10 mRNA content (or even cause a decrease) in a human monocytic cell line U937. Undetectable levels of IL-12 protein were found in the cell line although the transcripts were present in the cells at first hours p.i. It appears now that vaccinia virus transiently and sequentially induces IL-12 and IL-10 in human monocytes.

Changes in alpha-1-antichymotrypsin expression in vaccinia virus infected HepG2 cells.

Human hepatoma cells (HepG2) synthesize and secrete several plasma proteins that are inhibited in a time- and dose-dependent manner after vaccinia virus infection. However, infection of the HepG2 cells with a low dose of the virus (up to 1 plaque forming unit/cell) stimulated the expression of alpha-1-antichymotrypsin, which was demonstrated by means of electroimmunoassay and Northern blot analysis. This stimulation appeared to be on the level of transcription as shown in transient transfection experiments using various alpha-1-antichymotrypsin gene promoter constructs. In contrast to interleukin-6, virus-induced activation of the alpha-1-antichymotrypsin gene transcription does not require the STAT (signal transducers and activators of transcription) binding elements present in the alpha-1-antichymotrypsin gene promoter. Furthermore, alpha-amanitin, which inhibits eukaryotic RNA polymerase II and III, did not affect alpha-1-antichymotrypsin stimulation by the virus, indicating involvement of the viral transcriptional apparatus in transient activation of alpha-1-antichymotrypsin gene expression.