Galacto-oligosaccharides to counter the side effects of antibiotic treatments

Antibiotic treatments are known to disturb the composition and metabolic activity of the human gut microbiota and, therefore, may lead to gut disorders. In this thesis, it was investigated whether and by which mechanisms galacto-oligosaccharides (GOS), a prebiotic known to stimulate the growth of bifidobacteria and to positively influence human health, may counter the negative effects of antibiotics on the microbiota. First, a high throughput approach combining the in vitro fermentation screening platform with a phylogenetic microarray read-outs was shown to be reliable to simultaneously analyse the effects of several often-used antibiotics on the intestinal microbiota. Then, using the same approach, the recovery of the composition and metabolic activity of the microbiota treated with four selected antibiotics upon GOS addition was shown to be antibiotic and dose dependant. The addition of GOS to an amoxicillin (AMX)-treated microbiota was considered successful as, after a decrease of the levelofBifidobacterium species, the recovery of mainly Bifidobacterium longum, was observed. The growth of bifidobacteria and the production of the beneficial butyrate tended to be higher upon addition of small GOS (dimers-trimers) than upon large GOS in non-treated microbiota (tetramers to hexamers). On the contrary in AMX-treated microbiota, the growth of bifidobacteria and production of butyrate tented to be higher upon addition of large GOS than upon addition of small GOS. The positive results of GOS on AMX-treated microbiota during in vitro experiments were evidenced in a double-blind randomized parallel intervention study involving 12 healthy adults. Overall, the addition of GOS, especially the large oligosaccharides, allowed the recovery of B. longum and, subsequently, stimulated the activity of the microbiota through cross-feeding after an AMX treatment.</p

Limited Increase of Particle Entrainment in the Off-Gas System of a Cold Crucible Induction Melter Compared with a Joule-Heated Metal Melter for HLLW Vitrification -11465

ABSTRACT Fission product solutions arising from reprocessing spent fuel from the nuclear reactors used for electrical production in France are immobilized in six vitrification lines at the AREVA La Hague plant. In 2010, the conventional Joule-heated metal melter was replaced in one of these six lines with a cold crucible melter. The cold crucible melter began vitrifying radioactive effluents produced by rinsing operations in legacy facilities in April 2010. The composition of these effluents requires a containment glass synthesis temperature that exceeds the operating temperatures limits of conventional (&quot;hot&quot;) melters. The cold crucible melter technology has three main advantages: melt temperatures well above the current limit, increased glass production capacity, extended lifetime because of the lower wall temperatures. For these reasons the cold crucible melter can subsequently be used to vitrify a wide range of High-Level Liquid Waste (HLLW). This paper describes the assessment performed to characterize the entrainment of particles or chemicals and/or radioactive species to the off-gas treatment system from a Joule-heated metal melter (JHMM) and from a cold crucible induction melter (CCIM). Vitrification is performed in a two-step process. A calciner is used in each case to dry and calcine the high-level liquid waste, supplying only the dry residue to the melter together with glass frit. The off-gas treatment is identical for both melters. The paper first describes how the CEA uses its reconfigurable vitrification prototype, a full-scale mockup of a La Hague vitrification line, in support of AREVA to anticipate cold crucible melter operation under radioactive conditions. It describes the process equipment constituting the vitrification line from the melter (using a JHMM or a CCIM) to the off-gas treatment system. All the differences that contribute to the modification of radioactive particle entrainment from the calciner/melter to the off-gas treatment system are then described. The results obtained are then discussed concerning the volatility of species produced by vitrification during weekly tests implementing either the conventional melting pot or the cold crucible melter. The distribution of volatile species in the off-gas treatment devices is discussed. The paper concludes with a discussion of how using the CCIM vitrification process on one of the La Hague vitrification units can achieve an increased vitrification throughput at a higher temperature without any impact on the resulting waste release

Vitrification of HLLW Surrogate Solutions Containing Sulfate in a Direct-Induction Cold Crucible Melter -9136

ABSTRACT Efforts were made in the People&apos;s Republic of China to solidify legacy high level liquid waste (HLLW) by the Liquid-Fed Ceramic Melter process (LFCM) in the 1990s. This process was to be a continuous process with high throughput as in the French Marcoule Vitrification Plant (AVM) or the LFCM. In this context, the CEA (Commissariat à l&apos;Energie Atomique is a French government-funded technological research organization) suggests the Cold Crucible Induction Melter (CCIM) technology that has been developed by the CEA since the 1980s to improve the performance of the vitrification process. In this context a series of vitrification tests has been carried out in a CCIM. CEA and AREVA have designed an integrated platform based on the CCIM technology on a sufficient scale to be used for demonstration programs of the one-step process. In 2003 a test was carried out at Marcoule in southern France on simulated HLLW with high sulfur content. In order to ensure the tests performed at Marcoule were consistent with the Chinese wasteforms, the glass frit was supplied by a Chinese Industry. The CCIM facility is described in detail, including process instrumentation. The test run is also described, including how the solution was directly fed on the surface of the molten glass. A maximum capacity was determined according to the applied process parameters including the high operating temperature. The electrical power supply characteristics are detailed and a glass mass balance is also presented covering more than seven hundred kilograms of glass produced in a sixty-hour test run

Rapid scanning spectrometric study of the transient species

Available from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Contribution of the Numerical Simulations in the Development of the French HLLW Vitrification Processes

International audienceFor many years, the CEA (Commissariat à l'Énergie Atomique et aux Énergies Alternatives) Marcoule and AREVA have developed various processes dedicated to radioactive waste confinement, especially vitrification processes for HLLW. For 10 years now, the numerical simulation has become an important tool for research and developement projects held in the CEA-AREVA Joint Vitrification Laboratory (LCV). Induction heating, fluid mechanics and thermal simulations take part of all new R&D projects. The apports of such simulations are, first, the enhancement of the working knowledge of existing process. Those data are very useful to define optimisation choices, for example upgrades made on the hot metallic melter used since the 1990s at LaHague facility. Second, the simulations are, of course, also used at the conception stage of new processes as a tool allowing wide ranges parametric tests. This has been extensively used in the design of the cold crucible inductive melter (CCIM) commissioned in 2010 at La Hague plant. Finally, it is a powerful tool for prospective studies for processes of the future. Whatever the purpose, the potential benefits are gains on the reliability, the output capacity and the life time

Impact of galacto-oligosaccharides on the gut microbiota composition and metabolic activity upon antibiotic treatment during in vitro fermentation

Prebiotics are considered to have potential to reduce disturbances in the gut microbiota induced by antibiotics. Results in literature are, however, not consistent. The current in vitro study conducted in a fermentation screening platform allowed to unambiguously compare the impact of galacto-oligosaccharides (GOS) on adult gut microbiota composition and activity upon treatment with four antibiotics at two doses. The changes in relative abundance of bacteria upon antibiotic treatment and the growth of Bifidobacterium and Lactobacillus upon GOS addition were antibiotic and dose dependant. This conclusion explains discrepancies in literature and indicates that particular combinations of GOS antibiotic should be studied. The combination GOS–Amoxicillin was especially of interest as, after decrease in Bifidobacterium levels, a recovery of mainly Bifidobacterium longum was observed and could be correlated with specific degradation patterns of GOS. Next to different degradation profiles of individual GOS, an accumulation of monosaccharides and intermediate organic acids was observed in antibiotic-treated microbiota as compared to nontreated microbiota. This showed that although GOS were utilized and beneficial bacteria could grow in 3 of 4 antibiotics tested, the metabolic activity of an antibiotic-treated microbiota was still disturbed as compared to the nontreated microbiota

In vitro fermentation of galacto-oligosaccharides and its specific size-fractions using non-treated and amoxicillin-treated human inoculum

In order to elaborate on the impact of amoxicillin treatment on the in vitro fermentation of specific structures of galacto-oligosaccharides (GOS), GOS was fractionated based on its degree of polymerization (DP) and the fermentation of individual DPs was studied. Different DP fractions of GOS and different isomeric structure within a DP fraction were preferentially degraded depending on the treatment applied to the microbiota. For the non-treated microbiota, the small DP fractions (dimers and trimers) were preferentially degraded as compared to the large DP fractions (tetramers till hexamers). ß-d-Gal-(1¿4/6)-d-Glc and ß-d-Gal-(1¿4)-ß-d-Gal-(1¿4)-d-Glc were the isomeric structures preferentially degraded within the DP2 and DP3 fraction, respectively. The fermentation of each size-fraction induced the production of various short chain fatty acids and the growth of several species of bifidobacteria. For amoxicillin-treated microbiota, the large size-fractions of GOS were preferentially degraded as compared to the small fractions. ß-d-Gal-(1¿4)-d-Gal and ß-d-Gal-(1¿4)-ß-d-Gal-(1¿3)-d-Glc were the isomeric structures preferentially degraded within the DP2 and DP3 fraction, respectively. Butyrate was only produced upon the fermentation of the large size-fractions. The differences in metabolic pattern of GOS depending on the treatment applied correlated with the changes in the microbiota composition, especially the growth of bifidobacteria. These results suggest that GOS, especially its large size-fractions, support the recovery of bifidobacteria and butyrate-producing bacteria after a treatment of the microbiota with amoxicillin

To what extent are microplastics from the open ocean weathered?

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