Showing papers by "Dominique Melck published in 2012"

NMR spectroscopy metabolomic profiling of exhaled breath condensate in patients with stable and unstable cystic fibrosis

Abstract: Background Metabolomics could provide new insights into the pathophysiology of cystic fibrosis (CF) by identifying profiles of endogenous metabolites. Objectives To investigate whether metabolomics of exhaled breath condensate could discriminate between patients with unstable CF, stable CF and healthy subjects, and whether selected metabolites were responsible for between-group differences. Methods Twenty-nine patients with stable CF, 24 with unstable CF and 31 healthy subjects (age 9–24 years) participated in a cross-sectional study. Metabolomics was performed with high-resolution nuclear magnetic resonance spectroscopy. Partial least squares-discriminant analysis was used as classifier. The results were validated in a second independent study. Results Intraclass correlation coefficients for between-day and technical repeatability were 0.93 and 0.96, respectively. Bland–Altman analysis showed good within-day repeatability. Correct classification rate of CF (n=53) vs healthy subjects (n=31) was 96% (R 2 =0.84; Q 2 =0.79). Model validation with a testing sample set obtained from subjects not included in the primary analysis (23 CF and 25 healthy subjects) showed a sensitivity of 91% and a specificity of 96%. The classification rate of stable CF (n=29) vs unstable CF patients (n=24) was 95% (R 2 =0.82; Q 2 =0.78). Model external validation in 14 patients with stable CF and 16 with unstable CF showed a sensitivity of 86% and a specificity of 94%. Ethanol, acetate, 2-propanol and acetone were most discriminant between patients with CF and healthy subjects, whereas acetate, ethanol, 2-propanol and methanol were the most important metabolites for discriminating between patients with stable and unstable CF. Conclusions Nuclear magnetic resonance spectroscopy of exhaled breath condensate is reproducible, discriminates patients with CF from healthy subjects and patients with unstable CF from those with stable CF, and identifies the metabolites responsible for between-group differences.

Nuclear magnetic resonance-based metabolomics of exhaled breath condensate: methodological aspects.

Abstract: To the Editors: Due to the lack of standardised procedures for exhaled breath condensate (EBC), a noninvasive technique for investigating lung inflammatory mediators [1], the between-laboratory comparison of results is difficult. Moreover, different collecting devices have been reported to influence the EBC content [2, 3]. The analysis of metabolic profiles (“metabolomics”) of EBC using nuclear magnetic resonance (NMR) spectroscopy discriminates between chronic obstructive pulmonary disease (COPD) patients and healthy subjects (HS) [4]; asthmatic children and HS [5]; and patients with stable cystic fibrosis and unstable cystic fibrosis and HS [6]. This approach has recently been questioned as NMR-based metabolomics of EBC collected using a condenser with reusable parts was reported to be affected by cleaning procedures, generating artificial signals that were not related to the endogenous metabolites of the lungs [7]. In this study we assessed the effects of a different cleaning procedure of a reusable-part condenser on EBC metabolomics; the possible time and carry-over effects when the same device is repeatedly used; technique sensitivity; the ability of NMR spectroscopy of EBC to discriminate between COPD patients and HS; and the potential of NMR spectroscopy in identifying selective EBC metabolites. If the cleaning procedure produces artificial signals in the NMR spectra of EBC, the separation between COPD patients and HS reported previously [4] is certainly surprising, as the residual signals derived from the disinfectant Descogen (Antiseptica chem.-pharm. Produkte GmbH, Pulheim/Brauweiler, Germnay) should have randomly affected both groups. Moreover, using a different reusable-part condenser, Carraro et al . [5] reported that NMR-based metabolomics of EBC differentiates asthmatic children from HS with a success rate of 86% [5]. To verify the influence of the disinfectant on EBC metabolomics, we modified the …

Chemo-ecological studies on hexactinellid sponges from the Southern Ocean

Abstract: Hexactinellids (glass sponges) are an understudied class with syncytial organization and poor procariotic associations, thought to lack defensive secondary metabolites. Poriferans, though, are outstanding sources of bioactive compounds; nonetheless, a growing suspicion suggests that many of these chemicals could be symbiont-derived. In Polar latitudes, sponges are readily invaded by diatoms, which could provide natural products. Hexactinellids are typical of deep waters; but in Antarctica, they dominate the upper shelf providing shelter and food supply to many opportunistic mesograzers and macroinvertebrates, which exert strong ecological pressures on them. Aiming to examine the incidence of defensive activities of hexactinellids against consumption, feeding experiments were conducted using their lipophilic fractions. Antarctic hexactinellid and demosponge extracts were tested against the asteroid Odontaster validus and the amphipod Cheirimedon femoratus as putative sympatric, omnivorous consumers. Hexactinellids yielded greater unpalatable activities towards the amphipod, while no apparent allocation of lipophilic defenses was noted. After chemical analyses on the lipophilic fractions from these Antarctic glass sponges, quite similar profiles were revealed, and no peculiar secondary metabolites, comparable to those characterizing other poriferans, were found. Instead, the lipidic compounds 5α(H)-cholestan-3-one and two glycoceramides were isolated for their particular outspread presence in our samples. The isolated compounds were further assessed in asteroid feeding assays, and their occurrence was evaluated for chemotaxonomical purposes in all the Antarctic samples as well as in glass sponges from other latitudes by NMR and MS. Characteristic sphingolipids are proposed as chemical markers in Hexactinellida, with possible contributions to the classification of this unsettled class.

Understanding UV-driven metabolism in the hypersaline ciliate Fabrea salina

Abstract: By using NMR spectroscopy, a non-invasive investigation technique, we performed in vivo experiments aimed at uncovering the metabolic pathways involved in the early response of Fabrea salina cells to ultraviolet (UV) radiation. This hypersaline ciliate was chosen as a model organism because of its well-known high resistance to UV radiation. Identical cell samples were exposed to visible radiation only (control samples, CS) and to UV-B + UV-A + visible radiation (treated samples, TS), and NMR spectra of in vivo cells were collected at different exposure times. Resonances were identified through one- and two-dimensional experiments. To compare experiments performed at variable irradiation times on different culture batches, metabolite signals affected by the UV exposure were normalized to corresponding intensity at τ = 0, the zero exposure time. The most affected metabolites are all osmoprotectants, namely, choline, glycine-betaine, betaines, ectoine, proline, α-trehalose and sucrose. The time course of these signals presents qualitative differences between CS and TS, and most of these osmoprotectants tend to accumulate significantly in TS in a UV dose-dependent manner. A picture of the immediate stress response of F. salina against UV radiation in terms of osmoprotection, water retention and salting-out prevention is described.