Specific appetite, energetic and metabolomics responses to fat overfeeding in resistant-to-bodyweight-gain constitutional thinness.

BACKGROUND: Contrasting with obesity, constitutional thinness (CT) is a rare condition of natural low bodyweight. CT exhibits preserved menstruation in females, no biological marker of undernutrition, no eating disorders but a bodyweight gain desire. Anorexigenic hormonal profile with high peptide tyrosine tyrosine (PYY) was shown in circadian profile. CT could be considered as the opposite of obesity, where some patients appear to resist diet-induced bodyweight loss. OBJECTIVE: The objective of this study was to evaluate appetite regulatory hormones in CTs in an inverse paradigm of diet-induced weight loss. METHODS: A 4-week fat overfeeding (2640 kJ excess) was performed to compare eight CT women (body mass index (BMI)<17.5 kg m(-)(2)) to eight female controls (BMI 18.5-25 kg m(-)(2)). Appetite regulatory hormones profile after test meal, food intake, bodyweight, body composition, energy expenditure and urine metabolomics profiles were monitored before and after overfeeding. RESULTS: After overfeeding, fasting total and acylated ghrelin were significantly lower in CTs than in controls (P=0.01 and 0.03, respectively). After overfeeding, peptide tyrosine tyrosine (PYY) and glucagon-like-peptide 1 both presented earlier (T15 min vs T30 min) and higher post-meal responses (incremental area under the curve) in CTs compared with controls. CTs failed to increase bodyweight (+0.22±0.18 kg, P=0.26 vs baseline), contrasting with controls (+0.72±0.26 kg, P=0.03 vs baseline, P=0.01 vs CTs). Resting energy expenditure increased in CTs only (P=0.031 vs baseline). After overfeeding, a significant negative difference between total energy expenditure and food intake was noticed in CTs only (-2754±720 kJ, P=0.01). CONCLUSION: CTs showed specific adaptation to fat overfeeding: overall increase in anorexigenic hormonal profile, enhanced post prandial GLP-1 and PYY and inverse to controls changes in urine metabolomics. Overfeeding revealed a paradoxical positive energy balance contemporary to a lack of bodyweight gain, suggesting yet unknown specific energy expenditure pathways in CTs.

Simultaneous analysis of the main markers of nitrogen status in dairy cow's urine using hydrophilic interaction chromatography and tandem mass spectrometry detection.

Microbial protein synthesis and nitrogen balance status in ruminants can be evaluated by the presence of metabolites in urine. This work aims to develop and validate a simple and sensitive method for simultaneous determination of nine markers of nitrogen status in ruminant's urine using hydrophilic interaction liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The LC-ESI-MS/MS system, operated in multiple reaction monitoring (MRM) in positive mode, was used for determining selected purine (allantoin, uric acid, xanthine, and hypoxanthine) and pyrimidine derivatives (ß-aminobutyric acid and ß-alanine), which are used to estimate rumen microbial protein synthesis - the main source of protein for ruminants. Creatinine, creatine and urea, three other metabolites involved in nitrogen metabolism were also measured by this method. The procedure was based on a simple dilution of urine samples in acetonitrile, followed by LC-ESI-MS/MS analysis. Chromatographic separation was tested with three different columns. A zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) column provided an optimal separation for all metabolites. Precision of the method was typically below 10%, and accuracy was above 90% with the exceptions of allantoin and urea at pH 6 and 3, and ß-alanine at pH 3. Metabolites were stable after 3 months of storage at -20°C, except for xanthine, hypoxanthine and ß-aminobutyric acid that lost up to 48, 50 and 39% of initial concentration after only 1month of storage in acidified urine. This LC-ESI-MS/MS method is more specific, unequivocally detecting target metabolites at lower detection limits than methods using UV detection. The method was suitable for the determination of all metabolites tested. The developed method was subsequently used to compare total and spot urine sampling obtained from dairy cows fed diets with contrasting levels of protein.

Acetaminophen metabolism after major surgery: a greater challenge with increasing age.

Patients undergoing major surgery represent a good model for the study of the hepatic metabolism of acetaminophen (APAP) after surgery and for the evaluation of how the detoxification process is influenced by aging. Thirty patients received intravenous APAP (1 g/6 h) for 4 days (D1-D4). Daily 24-h urinary metabolites-cysteine-APAP, mercapturate-APAP, APAP, and glucuronide and sulfate conjugates-as well as blood glutathione levels were compared with repeated-measures analysis of variance (significance, P<0.05). Between D1 and D4, cysteine-APAP increased (308±308 mg vs. 570±512 mg, P=0.005), and sulfate and glucuronide conjugates decreased (1,365±1,084 mg vs. 694±600 mg, P<0.0001 and 2,418±817 mg vs. 1,513±1,076 mg, P=0.011, respectively). Blood glutathione decreased (790±125 vs. 623±132 µmol/l, P<0.0001. These changes increased with aging. APAP disposition after major surgery shifts toward the oxidative pathways of metabolism, and this is enhanced with aging. Supplementation with sulfur-containing amino acids should be investigated further as it might minimize the effect on antioxidant defenses, especially in older persons undergoing more extensive surgical procedures.