95 research outputs found

    In vitro morphological studies on antibody-dependent nonimmune lymphocyte-mediated cytotoxicity in chronic active liver disease

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    Using an in vitro system of antibody-dependent cellular cytotoxicity (ADCC), the killing effect of chronic liver disease sera on target Chang cells, mediated by effector nonimmune lymphocytes (NLy), was studied. NLy destroyed Chang cells in monolayers pretreated with sera of patients with chronic active liver disease (CALD). Sera from these patients with CALD, after receiving steroid therapy, demonstrated a significant decrease of the cytotoxic action of NLy. The target cells treated with sera of normal subjects or patients with chronic persistent hepatitis were only minimally affected. Morphological observations of the cytotoxic action in a CALD serum-treated group showed intimate contact between NLy and the target cells in the areas of the plaques, where large numbers of the target Chang cells were injured and were closely associated with effector NLy. The Chang cells developed cytoplasmic swelling. The surface became ruffled, and intracytoplasmic organelles displayed vesicular degeneration. Thereafter, cell rupture and fragmentation occurred. The sera in patients with CALD appear to possess a membrane reactive factor, presumably antibody, against the surface membrane of Chang cells. This immunological mode of reaction between the effectors and target cells (ADCC) may be important in the perpetuation and pathogenesis of hepatocyte death in CALD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44386/1/10620_2005_Article_BF01073183.pd

    Determination of the selenium isotopic compositions in Se-rich yeast by hydride generation-inductively coupled plasma multicollector mass spectrometry

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    A method was developed for the precise determination of selenium isotopic compositions (delta Se-82/77, delta Se-82/76 and delta Se-82/74) by hydride generation inductively coupled plasma multiple collector mass spectrometry (HG-MC ICP MS) in Se-rich yeast. The conversion of all the selenium forms into Se(IV) during digestion and reduction steps was investigated by anion-exchange ICP quadrupole MS (SAX ICP Q MS) and was found to be complete. Measurement precision values expressed as deltas (delta) with regard to NIST SR M3149 were between 0.2-0.4 parts per thousand (2SD) over a period of 6 months for 25 or 50 ng mL(-1) of introduced selenium. The application of the method to the analysis of nine Se-rich yeast supplements from different manufactures showed significant variations in the isotope ratios suggesting that the latter can be an attractive parameter for the yeast provenance discrimination

    Water tracers in oilfield applications: Guidelines

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    International audienceA key parameter in tracing tests is the selection of the molecules used as water tracers. Many previous tests have failed because of improper selection of these molecules. To address this issue, the first part of this paper provides guidelines, offering data and advice for choosing the best possible tracers for a tracing campaign. This part of the paper presents the different types of water tracers proposed and used in oilfield applications, from the first qualitative tracer study in the 1960s to tracer studies in the 2000s, with their respective advantages and drawbacks. The oil industry began to conduct interwell tracer tests with molecules already successfully used in hydrology. These compounds included radioactive species and stable isotopes, chemicals such as fluorescent dyes, and inorganic ions. Some of the early chemical tracers have been rejected because of issues with adsorption onto the rock. Radioactive species, with a low detection limit, a low reactivity, and a low presence in the environment, have been widely used. However, their use has become more restricted throughout the world in response to the radioactive hazards associated with their use. Therefore, new types of non-radioactive tracers were developed and tested in the 1990s. Currently, however, few chemical molecules possess characteristics matching the selection criteria of an effective water tracer (with regard to environmental and economic aspects, etc.). The most effective molecules currently used as water tracers are the fluorinated benzoic acids (FBA); these molecules can be detected with very low limits of detection (LOD) using analytical techniques such as gas chromatography or ultra-high-performance liquid chromatography coupled with mass spectrometers (GC/MS and UHPLC/MS-MS, respectively).The second part of the paper deals with the analytical aspect of a tracing test. An alternative technique to the fluorescence methods currently used for the naphthalene sulfonic acids (NSA) is proposed: UHPLC/MS-MS. With this original tool, FBA and NSA could be simultaneously detected in water samples in only one 5-min analysis. Other molecules, halogenated boronic acids, were also tested analytically for their potential application as tracers. However, these molecules were not retained because of their overly high LOD, requiring the injection of large quantities into oil reservoirs. © 2012 Elsevier B.V

    Impacts of bioremediation schemes for the mitigation of a low-dose anthracene contamination on free-living marine benthic nematodes

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    A microcosm experiment was used to examine (1) the effects of different bioremediation schemes on degradation of anthracene and the structure of free-living marine nematodes in a lightly contaminated (4.5 mu g g(-1)) sediment from Bizerte lagoon and (2) the responses of the nematode community upon an artificial spiking of a low dose anthracene (1 mu g g(-1)). For that purpose sediment microcosms were incubated in laboratory for 40 days. Bioremediation techniques decreased the anthracene contamination, and interestingly, biodegradation were more efficient when anthracene was artificial supplied into the sediment suggesting that the addition of bioavailable anthracene stimulated the bacterial community to adjust towards a PAH-degrading community. Spiking with this low dose of anthracene provoked significant changes in the nematode community structure and abundance, with the elimination of specific species such as Mesacanthion diplechma, the decrease of the dominant species Oncholaimus campylocercoides and the increase in abundance of opportunistic species such as Spirinia parasitifera. This would suggest a low tolerance of the nematode community despite the presence of a weak anthracene contamination in the sediment that could have allow dominance of an anthracene tolerant nematode species. Anthracene toxicity was alleviated in biostimulation treatments, leading to a strong increase in nematode abundance, concomitantly with changes in the nematode community structure; Prochromadorella neapolitana became the most abundant species

    Changes of benthic bacteria and meiofauna assemblages during bio-treatments of anthracene-contaminated sediments from Bizerta lagoon (Tunisia)

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    Sediments from Bizerta lagoon were used in an experimental microcosm setup involving three scenarios for the bioremediation of anthracene-polluted sediments, namely bioaugmentation, biostimulation, and a combination of both bioaugmentation and biostimulation. In order to investigate the effect of the biotreatments on the benthic biosphere, 16S rRNA gene-based T-RFLP bacterial community structure and the abundance and diversity of the meiofauna were determined throughout the experiment period. Addition of fresh anthracene drastically reduced the benthic bacterial and meiofaunal abundances. The treatment combining biostimulation and bioaugmentation was most efficient in eliminating anthracene, resulting in a less toxic sedimentary environment, which restored meiofaunal abundance and diversity. Furthermore, canonical correspondence analysis showed that the biostimulation treatment promoted a bacterial community favorable to the development of nematodes while the treatment combining biostimulation and bioaugmentation resulted in a bacterial community that advantaged the development of the other meiofauna taxa (copepods, oligochaetes, polychaetes, and other) restoring thus the meiofaunal structure. The results highlight the importance to take into account the bacteria/meiofauna interactions during the implementation of bioremediation treatment
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