Glycerol metabolism in patients with alcohol-induced liver cirrhosis

Serum metabolic signature of minimal hepatic encephalopathy by (1)H-nuclear magnetic resonance

Minimal hepatic encephalopathy (MHE) reduces quality of life of cirrhotic patients, predicts overt hepatic encephalopathy, and is associated with poor prognosis. We hypothesized that MHE arises once metabolic alterations derived from the liver reach a particular threshold. Our aim was to assess whether metabolic profiling of serum samples by high-field (1)H-nuclear magnetic resonance spectroscopy ((1)H NMR) and subsequent multivariate analyses would be useful to characterize metabolic perturbations associated with MHE and to identify potential metabolic biomarkers. Metabolic serum profiles from controls (n = 69) and cirrhotic patients without MHE (n = 62) and with MHE (n = 39) were acquired using high field NMR. Supervised modeling of the data provided perfect discrimination between healthy controls and cirrhotic patients and allowed the generation of a predictive model displaying strong discrimination between patients with and without MHE (R(2)Y = 0.68, Q(2)Y = 0.63). MHE patients displayed increased serum concentrations of glucose, lactate, methionine, TMAO, and glycerol, as well as decreased levels of choline, branch amino acids, alanine, glycine, acetoacetate, NAC, and lipid moieties. Serum metabonomics by (1)H NMR offers a useful approach for characterizing underlying metabolic differences between patients with and without MHE. This procedure shows great potential as a diagnostic tool of MHE as it objectively reflects measurable biochemical differences between the patient groups and may facilitate monitoring of both disease progression and effects of therapeutic treatments.

Glucose infusion does not suppress increased lipolysis after abdominal surgery

The purpose of this study was to investigate the effect of glucose infusion on lipid metabolism after abdominal surgery. Patients (n = 6) with non-metastasized colorectal carcinoma were investigated on the second day after surgery and healthy volunteers were studied after an overnight fast. The rates of glycerol appearance (R(a) glycerol), i.e., lipolysis rates, were assessed by primed continuous infusion of [1,1,2,3,3,-5H2]glycerol before and after 3 h of glucose infusion (4 mg x kg(-1) x min(-1)). Plasma concentrations of glycerol, free fatty acids, glucose, lactate, insulin, and glucagon were determined. Fasting R(a) glycerol was higher in patients than in volunteers (7.7 +/- 1.8 versus 1.9 +/- 0.3 micromol x kg(-1) x min(-1), P < 0.05). Glucose infusion suppressed the R(a) glycerol in volunteers to 1.0 +/- 0.2 micromol x kg(-1) x min(-1) (P < 0.05), whereas lipolysis was not affected in patients. Plasma concentrations of glycerol and free fatty acids similarly decreased during glucose administration by 50% in both groups (P < 0.05). In contrast to the patients, a significant correlation (r = 0.78, P < 0.05) between the R(a) glycerol and plasma glycerol concentration was observed in normal subjects. The hyperglycemic response to glucose infusion was significantly more pronounced (P < 0.05) in patients (10.7 +/- 0.7 mmol/L) than in volunteers (7.1 +/- 0.4 mmol/L), whereas the plasma insulin increased to the same extent in the two groups (P < 0.001). In conclusion, lipolysis rates are increased after abdominal surgery and glucose administration, most likely due to insulin resistance, and fail to inhibit stimulated whole-body lipolysis.