968 research outputs found

    An overview of the geochemical characteristics of oceanic carbonatites: New insights from Fuerteventura carbonatites (Canary islands)

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    The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This paper provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis. We present new data on trace elements in minerals and whole-rock, together with the first noble gases isotopic study (He, Ne, Ar) in apatite, calcite, and clinopyroxene from Fuerteventura carbonatites (Canary Islands). Trace elements show a similar trend as Cape Verde carbonatites, almost tracing the same patterns on multi-element and REE abundance diagrams.3He/4He isotopic ratios of Fuerteventura carbonatites reflect a shallow (sub-continental lithospheric mantle, SCLM) He signature in their petrogenesis, and they clearly differ from Cape Verde carbonatites, i.e., fluids from a deep and low degassed mantle with a primitive plume-derived He signature are involved in their petrogenesis

    Reaction between quinone and thiazolidine. A study on the formation mechanism of new antiproliferative quinolindiones

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    Reaction between quinolinquinone and thiazolidine in basic medium was investigated. 2-Arylthiazolidine-4-carboxylic acid ethyl esters undergo two different cleavages in basic medium, yielding the 1-aryl-2-azadiene and a thiolic species. In the presence of quinolinquinone, the isomeric 1-aryl-3-ethoxycarbonyl-pyridoisoquinolin-5,10-diones and 3-amino-3-ethoxycarbonyl-dihydrothienoquinolin- 4,9-diones are formed by a hetero-Diels–Alder reaction and 1,4-Michael addition reaction, respectively. A mechanism for the formation of the reaction products is presented

    A LA-ICP-MS STUDY OF CARBONATITES FROM FUERTEVENTURA, CANARY ISLAND

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    Carbonatites complexes are very rare in oceanic environments and in the Atlantic Ocean they can be only found at Cape Verde islands and Fuerteventura. Fuerteventura is the second largest island in the Canary Archipelago and is located on a transitional, continental to oceanic, crust. It consists essentially of Mesozoic sediments, submarine volcanic rocks, subaerial basaltic and trachytic series, ultramafic, mafic to felsic intrusives (clinopyroxenites, melteijites-ijolites, nepheline-monzogabbros, nepheline-sienites) and carbonatitic dike swarms (age 25 Ma). Carbonatite dike (Ca-carbonatites) mineralogy consists of calcite, aegirine-augite, albite, K-feldspar, biotite, apatite, Fe-Ti oxides and accessory minerals, such as zircon, barite, monazite and pyrochlore. The degree of alteration of carbonatites (evaluated by DTA and XRD) is generally low, with the occurrence of illite-montmorillonite mixed layers, vermiculite and chlorite. Whole rock samples (XRF) are high in CaO (> 50 %) and SrO (> 2-3 %) and very low in MgO (< 1-2 %). Trace elements were determined by LA-ICP-MS on calcite and accessory minerals (pyrochlore, monazite, zircon). Results show in calcite phenocrysts REE patterns highly enriched in all REEs (sum REE= 1186-2943 ppm) and particularly in LREE: LaN = 2178 (chondrite normalized), CeN = 1499, with respect to HREE (YbN = 37, LuN = 34) and rather fractionated pattern (La/Yb)N = 58. Small negative Eu anomalies do also occur (Eu/Eu* = 0.77 - 0.94) and these are coupled with high Sr anomalies (Sr/Sr* = 28.3 - 58.7). REE in pyrochlore are extremely enriched in REE (sum REE= 12.8 wt %) with very high LREE (LaN = 71214 and CeN = 62803) and HREE (YbN = 997, LuN = 695) with a slightly steeper pattern if compared to calcite: (La/Yb)N = 71. No significative Eu anomalies were found (Eu/Eu* = 1.06), while there is a conisistent Sr positive anomaly in spiderdiagrams (Sr/Sr* = 1.74). Preliminar results show that pyrochlore is the main mineral repository of REEs and its occurrence, even in trace amounts, gives the fingerprint to trace element to whole rock

    A parathyroid-hormone-related-protein (PTH-rP)-specific cytotoxic T cell response induced by in vitro stimulation of tumour-infiltrating lymphocytes derived from prostate cancer metastases, with epitope peptide-loaded autologous dendritic cells and low-dose IL-2

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    Bone metastases are one of the most common events in patients with prostate carcinoma. PTH-rP, a protein produced by prostate carcinoma and other epithelial cancers, is a key agent for the development of bone metastases. A PTH-rP-derived peptide, designated PTR-4 was identified, which is capable to bind HLA-A2.1 molecules and to generate PTH-rP-specific cytotoxic T cell (CTL) lines from healthy HLA-A2.1+ individual peripheral-blood-mononuclear-cells (PBMC). In this model, we investigated the in vitro possibility of generating an efficient PTH-rP specific CTL response by cyclical stimulations with IL-2 and PTR-4 peptide-pulsed autologous dendritic cells (DC), of HLA-A2.1+ tumour infiltrating lymphocytes (TIL) derived from a patient with metastatic prostate carcinoma. A T cell line generated in this way (called TM-PTR-4) had a CD3+, CD5+, CD4−, CD8+, CD45Ro+, CD56− immunophenotype and a HLA-A2.1 restricted cytotoxic activity to PTR-4-peptide pulsed CIR-A2 (HLA-A2.1+) target cells, PTH-rP+/HLA-A2.1+ CIR-A2 transfected with PTH-rP gene, prostate carcinoma LNCaP cells, and autologous metastatic prostate cancer cells (M-CaP). These lymphocytes were not cytotoxic to HLA-A2.1+ targets not producing PTH-rP, such as peptide-unpulsed CIR-A2 and colon carcinoma SW-1463, cell lines. Our results provide evidence that PTR-4 peptide-pulsed autologous DC may break the tolerance of human TIL against the autologous tumour by inducing a PTH-rP-specific CTL immune reaction. In conclusion PTR-4 peptide-pulsed autologous DC may be a promising approach for vaccine-therapy and antigen-specific CTL adoptive immunotherapy of hormone-resistant prostrate cancer. © 2001 Cancer Research Campaign http://www.bjcancer.co

    The Eigenvalue Analysis of the Density Matrix of 4D Spin Glasses Supports Replica Symmetry Breaking

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    We present a general and powerful numerical method useful to study the density matrix of spin models. We apply the method to finite dimensional spin glasses, and we analyze in detail the four dimensional Edwards-Anderson model with Gaussian quenched random couplings. Our results clearly support the existence of replica symmetry breaking in the thermodynamical limit.Comment: 8 pages, 13 postscript figure

    Population screening for colorectal cancer by flexible sigmoidoscopy or CT colonography: Study protocol for a multicenter randomized trial

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    BACKGROUND: Colorectal cancer (CRC) is the second most prevalent type of cancer in Europe. A single flexible sigmoidoscopy (FS) screening at around the age of 60 years prevents about one-third of CRC cases. However, FS screens only the distal colon, and thus mortality from proximal CRC is unaffected. Computed tomography colonography (CTC) is a highly accurate examination that allows assessment of the entire colon. However, the benefit of CTC testing as a CRC screening test is uncertain. We designed a randomized trial to compare participation rate, detection rates, and costs between CTC (with computer-aided detection) and FS as primary tests for population-based screening. METHODS/DESIGN: An invitation letter to participate in a randomized screening trial comparing CTC versus FS will be mailed to a sample of 20,000 people aged 58 or 60 years, living in the Piedmont region and the Verona district of Italy. Individuals with a history of CRC, adenomas, inflammatory bowel disease, or recent colonoscopy, or with two first-degree relatives with CRC will be excluded from the study by their general practitioners. Individuals responding positively to the invitation letter will be then randomized to the intervention group (CTC) or control group (FS), and scheduled for the screening procedure. The primary outcome parameter of this part of the trial is the difference in advanced neoplasia detection between the two screening tests. Secondary outcomes are cost-effectiveness analysis, referral rates for colonoscopy induced by CTC versus FS, and the expected and perceived burden of the procedures. To compare participation rates for CTC versus FS, 2,000 additional eligible subjects will be randomly assigned to receive an invitation for screening with CTC or FS. In the CTC arm, non-responders will be offered fecal occult blood test (FOBT) as alternative screening test, while in the FS arm, non-responders will receive an invitation letter to undergo screening with either FOBT or CTC. Data on reasons for participation and non-participation will also be collected. DISCUSSION: This study will provide reliable information concerning benefits and risks of the adoption of CTC as a mass screening intervention in comparison with FS. The trial will also evaluate the role of computer-aided detection in a screening setting. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0173960

    The route to solve the interplay between inflammation, angiogenesis and anti-cancer immune response

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    Even though the crucial role played by inflammation in cancer development and progression was first hypothesized by Rudolf Virchow at the beginning of the nineteenth century, only recently inflammation has been recognized as a hallmark of cance

    Computational core and fixed-point organisation in Boolean networks

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    In this paper, we analyse large random Boolean networks in terms of a constraint satisfaction problem. We first develop an algorithmic scheme which allows to prune simple logical cascades and under-determined variables, returning thereby the computational core of the network. Second we apply the cavity method to analyse number and organisation of fixed points. We find in particular a phase transition between an easy and a complex regulatory phase, the latter one being characterised by the existence of an exponential number of macroscopically separated fixed-point clusters. The different techniques developed are reinterpreted as algorithms for the analysis of single Boolean networks, and they are applied to analysis and in silico experiments on the gene-regulatory networks of baker's yeast (saccaromices cerevisiae) and the segment-polarity genes of the fruit-fly drosophila melanogaster.Comment: 29 pages, 18 figures, version accepted for publication in JSTA
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