Safety and efficacy of small bowel polypectomy using a balloon-assisted enteroscope in pediatric patients with Peutz-Jeghers syndrome. / Seguridad y eficacia de la polipectomía en intestino delgado utilizando enteroscopio asistido por balones en pacientes pediátricos con síndrome de Peutz-Jeghers.

INTRODUCTION AND AIMS: Peutz-Jeghers syndrome is an autosomal dominant inherited pathology characterized by gastrointestinal hamartomatous polyps, predominantly in the small bowel, and pigmented mucocutaneous lesions. Guidelines suggest polypectomy with a balloon-assisted enteroscope when polyps are larger than 10mm. Complications in adults can be as high as 6.8%, but there is little information on pediatric populations. Our aim was to describe the safety and efficacy of polypectomy in a group of pediatric patients with Peutz-Jeghers syndrome using balloon-assisted enteroscopy. MATERIALS AND METHODS: A retrospective study was conducted at the Hospital de Especialidades del Centro Médico Nacional Siglo XXI on pediatric patients with Peutz-Jeghers syndrome that required balloon-assisted enteroscopy and polypectomy within the time frame of January 2010 and December 2015. Patients that underwent polypectomy with a push enteroscope were excluded from the study. RESULTS: A total of 35 polypectomies were performed on 4 patients (female/male: 3/1). The mean age of the patients was 13.7 years (range:11-16). Twelve enteroscopies were carried out, 8 of which were anterograde. A single-balloon enteroscope was used in 7 procedures and a double-balloon enteroscope in 5. The mean size of the polyps was 1.6cm (range: 1-4cm). A major complication (acute pancreatitis) presented in only one case (8.3%). No other major complications associated with the procedures were observed. CONCLUSION: Balloon-assisted enteroscopy with polypectomy in children is a safe and effective procedure, with complications similar to those reported in adults.

Cd-induced phytochelatin synthesis in Dittrichia viscosa (L.) Greuter is determined by the dilution of the culture medium.

In this paper, we examined Cd accumulation and PC synthesis in two clones of Dittrichia viscosa, one with a metallicolous (DV-A) and the other with a non-metallicolous origin (DV-W). The clones were cultured in vitro with 0 and 10 mg Cd L(-1) in both short-term treatments (up to 72 h) and over 10 days. We also examined the influence of the culture medium dilution and the PC-synthesis inhibitor, L-buthionine-sulfoximine (BSO), on these parameters. Similar Cd accumulation values were found in the two clones. No synthesis of new thiolic compounds was observed in Cd-treated plants cultured in vitro in Murashige and Skoog medium up to 72 h when compared to controls. Dilution of the culture medium affected PC production, increasing it in 1/2 MS and especially in 1/4 MS. Cd uptake did not increase in the same way, but still hyperaccumulation levels were exceeded in all Cd treatments. BSO addition increased the sensitivity of D. viscosa to Cd and diminished Cd accumulation. Nevertheless, a poor correlation between PCs and Cd accumulation capacity was observed since the highest Cd content did not correspond to the highest PC levels. All these results obtained suggest that PCs are important in Cd accumulation and detoxification in D. viscosa and also that other mechanisms might be involved in these traits.

Investigations into the differential reactivity of endogenous and exogenous mercury species in coastal sediments.

Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1.2 %) than in the lagoonal sediment (0.5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2.0-4.3 times higher than the endogenous one. Its methylation was just slightly higher (1.4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3.6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.

An experimental approach to investigate mercury species transformations under redox oscillations in coastal sediments.

This work describes a laboratory experiment designed to unravel mercury species reactivity in superficial coastal sediments oscillating between oxic and anoxic conditions. The experimental set-up has been applied to a sediment slurry from the Arcachon Bay (France) to follow the evolution of both naturally occurring (i.e. endogenous) and isotopically enriched added mercury species (i.e. exogenous, ¹99IHg and ²°¹MMHg) at environmental levels. The transformation and partition between the different phases (aqueous, solid and gaseous) of the endogenous and exogenous mercury species (inorganic Hg (IHg), monomethyl Hg (MMHg), elemental Hg (Hg°) and dimethyl Hg (DMHg)) have been investigated by isotopic speciation methods throughout the experiment. The results demonstrate that the experimental approach is able to promote sediment redox oscillations and to simultaneously follow the biogeochemical fate of naturally occurring or added mercury species. Experimentally driven redox transition events were found to significantly enhance the aqueous Hg species concentrations, while the MMHg burden is not greatly affected. Indeed, during the anoxic-oxic transition, while aqueous endogenous IHg and MMHg exhibited a two-fold increase, aqueous exogenous IHg and MMHg increased 7 and 4 times, respectively. Transient increases of the net IHg methylation were recorded during the redox transitions with the largest increase of the MMHg contents (factor 1.8) observed during the oxic-anoxic transition. High resolution in situ redox experiments have not been performed up to now, therefore the developed experimental set-up provides novel insights in both the influence of redox conditions on Hg methylation/demethylation and adsorption/desorption processes and kinetics in superficial sediments.

Determination of the uncertainties in the theoretical mass isotopomer distribution of molecules.

A procedure for the determination of the uncertainties in the theoretical mass isotopomer distribution of molecules due to natural variations in the isotope composition of their constituting elements is described here for the first time. For this purpose, a Visual Basic macro for Microsoft Excel was written by adapting the direct stepwise calculation algorithm published by Kubinyi (Anal. Chim. Acta 1991, 247, 107-119, Fig. 1). In our procedure no pruning threshold factors were used to eliminate round up errors for large molecules. Then, the Kragten procedure of uncertainty propagation (Analyst 1994, 119, 2161-2165) was applied taking into account the correlation coefficients between the isotope abundances of the corresponding atoms. For bi-isotopic elements (C, H, N, Cl, Br) the correlation coefficients were given the value of -1. For tri- and tetra-isotopic elements the correlation coefficients were calculated using the mass dependent fractionation law used in stable isotope geochemistry and values of +1 or -1 were obtained depending on the isotope system considered. It was observed that for small organic molecules of natural isotope abundances, such as phenol or polybrominated diphenylethers, the method provided relatively small propagated uncertainties similar in magnitude to those measured experimentally. For (13)C-labelled molecules the calculated uncertainties were mainly due to the uncertainties in the isotope enrichment of (13)C and were much larger than the experimental uncertainties. For large molecules of natural isotope abundances, such as peptide C(68)H(107)N(17)O(25) (NIST 8327 RM), the uncertainties in their mass isotopomer distributions were much larger and their source could be assigned mainly to the uncertainty of the natural isotope composition of carbon. When the size of the molecule was even larger, such as bovine insulin (C(254)H(377)N(65)O(75)S(6)), Kragten procedure provided a good estimate for the uncertainty when the most probable isotope composition of carbon in mammals was used in the calculations.

Occurrence and distribution of organotin compounds in leachates and biogases from municipal landfills.

The occurrence and distribution of organotin compounds (OTC) in effluents from two different landfills were investigated through the combination of three different analytical methodologies. In this way, the determination of the volatile OTC in biogases, the dissolved volatile and dissolved ionic organotin species in leachates was carried out using these complementary approaches. In leachates, up to nine OTC (i.e. methyltin, ethyltin, butyltin and mixed methyl-ethyltins) were detected at concentrations ranging from 0.01 to 6.5 microg (Sn)L(-1), which represents 1-38% of the total tin concentration. In biogases, five volatile tin species (i.e. methyltin, mixed methyl-ethyltin and ethyltin) were determined at significant concentrations reaching up to 25 microg (Sn)m(-3). The occurrence of the overall identified species is explained by both organotin-containing waste and endogenous alkylation pathways. Two parameters seem to significantly influence the effluent OTC composition: first, wet depositions both induce leachate dilution and alter methylation/ethylation mechanisms; second, evolution of the waste degradation stage yields different volatilisation mechanisms (i.e. permethylation or perethylation). The results obtained in this work outline the diversity and variability of the organotin contamination routes provided by multiple pathways. These phenomena can lead to the release of biologically harmful species in the environment if no efficient effluent treatment is applied.

La insuficiencia cardíaca en la práctica asistencial del internista / Cardiac failure in the health care practice of the internist

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Comparison of different chloroformates for the derivatisation of seleno amino acids for gas chromatographic analysis.

Three chloroformate reagents, ethyl chloroformate (ECF), methyl chloroformate (MCF) and menthyl chloroformate (MenCF), have been used for the derivatisation of seleno amino acids and their performance was compared. Chromatographic parameters and the inertness of the different instrumental configurations used (gas chromatography-atomic emission detection (GC-AED), and GC-MS) were shown to have a significant influence on the detection of various seleno amino acids (selenomethione, selenoethione and selenocysteine) and some sulphur-containing amino acids (methionine, cysteine, cystine and methylcysteine) which were included in the experiments for comparison. Methyl chloroformate was the preferred derivatisation reagent, since it generally performed best in terms of derivatisation yield and reproducibility and also showed less significant conditioning effects than ethyl chloroformate. Methyl and ethyl chloroformate derivatives of selenomethionine, selenoethionine, cysteine and methionine were detectable, while the detection of the menthyl chloroformate derivatives of selenocystine and cystine was not reproducible. Overall efficiencies for the determination of selenomethionine and selenoethionine from aqueous extracts ranged from 40 to 100% for methyl chloroformate, over 30-75% for ethyl chloroformate to 15-70% for menthyl chloroformate for different series measured over a period of months. The relative standard deviation of the method for the methyl and menthyl chloroformate derivatisation ranged from 7 to 13% without internal standard and was improved to 2% for the determination of selenomethionine using selenoethionine as internal standard. This indicates that, despite the limited reproducibility of the method, its repeatability is good enough to allow accurate determination of seleno amino acids, which was also demonstrated by the analysis of selenium supplementation tablets for human diet that contained selenomethionine.