Brigitte Wuyts

Propionate absorbed from the colon acts as gluconeogenic substrate in a strict carnivore, the domestic cat (Felis catus)

In six normal-weight and six obese cats, the metabolic effect of propionate absorbed from the colon was assessed. Two colonic infusions were tested in a crossover design with intervals of 4 weeks. The test solution contained 4 mmol sodium propionate per kg ideal body weight in a 0.2% NaCl solution. Normal saline was given as control solution. Solutions were infused into the hindgut over 30 min. Blood samples were obtained prior to and at various time points after starting the infusion. As body condition did not affect evaluated parameters, all data were pooled. Plasma glucose concentrations showed differences neither over time nor during or after infusion with propionate or control. Plasma amino acid concentrations rose over time (p < 0.001), but were similar for both infusions. Plasma propionylcarnitine rose markedly towards the end of the propionate infusion and decreased afterwards (p < 0.001), whereas 3-hydroxy-3-methylglutarylcarnitine was lower 30 (p = 0.005) and 60 min (p = 0.032) after ending propionate infusions and acetylcarnitine tended to fall at the same time points (p = 0.079; p = 0.080), suggesting inhibition of gluconeogenesis from pyruvate and amino acids, but initiation of propionate-induced gluconeogenesis. In conclusion, propionate absorbed from the colon is hypothesized to act as gluconeogenic substrate, regardless of the cats body condition.

Does canine inflammatory bowel disease influence gut microbial profile and host metabolism

BackgroundInflammatory bowel disease (IBD) refers to a diverse group of chronic gastrointestinal diseases, and gut microbial dysbiosis has been proposed as a modulating factor in its pathogenesis. Several studies have investigated the gut microbial ecology of dogs with IBD but it is yet unclear if this microbial profile can alter the nutrient metabolism of the host. The aim of the present study was to characterize the faecal bacterial profile and functionality as well as to determine host metabolic changes in IBD dogs.Twenty-three dogs diagnosed with IBD and ten healthy control dogs were included. Dogs with IBD were given a clinical score using the canine chronic enteropathy clinical activity index (CCECAI). Faecal short-chain fatty acids (SCFA) and ammonia concentrations were measured and quantitative PCR was performed. The concentration of plasma amino acids, acylcarnitines, serum folate, cobalamin, and indoxyl sulfate was determined.ResultsNo significant differences in the abundance of a selection of bacterial groups and fermentation metabolites were observed between the IBD and control groups. However, significant negative correlations were found between CCECAI and the faecal proportion of Lactobacillus as well as between CCECAI and total SCFA concentration. Serum folate and plasma citrulline were decreased and plasma valine was increased in IBD compared to control dogs. Increased plasma free carnitine and total acylcarnitines were observed in IBD compared with control dogs, whereas short-chain acylcarnitines (butyrylcarnitine + isobutyrylcarnitine and, methylmalonylcarnitine) to free carnitine ratios decreased. Dogs with IBD had a higher 3-hydroxyisovalerylcarnitine + isovalerylcarnitine to leucine ratio compared to control dogs.ConclusionsCanine IBD induced a wide range of changes in metabolic profile, especially for the plasma concentrations of short-chain acylcarnitines and amino acids, which could have evolved from tissue damage and alteration in host metabolism. In addition, dogs with more severe IBD were characterised by a decrease in faecal proportion of Lactobacillus.

Variable column length method development strategy for amino acid analysis in serum samples of neonates with metabolic disorders

Accurate quantitative analysis of amino acids forms an important part of targeted metabolic profiling as deviations from normal amino acid profiles can be indicative of several inborn metabolic disorders. A variable-length method development strategy for HPLC analysis on superficially porous particle columns using UV detection is proposed for the separation of 21 primary amino acids. This strategy consists of the evaluation of a large set of gradient and mobile phase compositions on short columns with different stationary phase properties to rapidly determine the best separation conditions leading to the highest number of separated peaks. These conditions are subsequently used to optimize the separation on a longer column length benefitting from its higher separation performance. A minimum critical resolution of 2.0 and a maximum analysis time of 10min were imposed to allow for accurate, robust and rapid quantitation of all amino acids over a large linear range. For amino acids playing a key role in commonly encountered amino acid and urea cycle disorders, a minimum critical resolution of 2.5 was pursued. Mass spectrometry was used for fast peak tracking during the method development procedure. It was demonstrated that the retention behavior of the studied amino acids is more pressure than temperature dependent. This allowed performing the entire method development strategy at the same maximum pressure on all column lengths, while preserving the retention profile, resulting in a significant time profit for the initial scouting runs. The applicability of the method was demonstrated by analyzing serum samples of several neonates diagnosed with metabolic disorders such as maple syrup urine disorder, phenylketonuria and citrullinemia.