Does glutamine-enriched parenteral nutrition really affect intestinal morphology and gut permeability?

BACKGROUND: Nutritional depletion has been related to low glutamine levels in plasma and gut mucosa. This study was set up to investigate the effects of glutamine-enriched total parenteral nutrition on intestinal morphology and permeability. METHODS: Twenty-three depleted patients were randomized and after stabilization baseline measurements were performed. Plasma glutamine concentrations, gut morphology (including proliferation and lymphocyte markers) and intestinal permeability were measured. After administration during 8-10 days of a glutamine enriched total parenteral nutrition or an isonitrogenous control solution the measurements were repeated. RESULTS: No significant changes in glutamine concentrations, intestinal permeability, mucosal morphology or gut mucosal inflammation were observed between groups. CONCLUSIONS: Glutamine enriched total parenteral nutrition in a depleted patient population does not result in improvements in gut morphology and gut barrier function.

Assessment of whole body protein metabolism in critically ill children: can we use the [15N]glycine single oral dose method?

BACKGROUND & AIMS: Most stable-isotope methods to evaluate whole body protein metabolism in patients are invasive and difficult to use in children. In this study protein metabolism was evaluated with the non-invasive [15N]glycine single oral dose method in critically ill children and the value of the method is discussed. METHODS: [15N]glycine (100mg) was given orally to children (mean age 5.5 years; range 0.6-15.5 years) with meningococcal septic shock (MSS, n = 8), pneumonia (n = 5), and to healthy, fed and post-absorptive children (n = 10). Urine was collected during 9h, total amount of NH(3), labelled NH(3) and nitrogen were measured, and protein turnover, synthesis and breakdown were calculated using urinary NH(3) as end-product. RESULTS: Mean protein turnover in children with MSS, pneumonia and fed and post-absorptive healthy children was 0.63+/-0.13, 0.38+/-0.10, 0.28+/-0.03 and 0.28+/-0.02g N/kg/9h, respectively. Mean protein synthesis was 0.55+/-0.12, 0.29+/-0.09, 0.18+/-0.02, 0.20+/-0.02g N/kg/9h, respectively. Mean protein breakdown was 0.56+/-0.14, 0.28+/-0.12, 0.08+/-0.03, 0.28+/-0.02g N/kg/9h, respectively. Protein turnover, synthesis and breakdown were significantly increased in MSS patients compared to fed healthy children (P <0.01) and post-absorptive children (P <0.05). Protein turnover, protein synthesis, protein breakdown were significantly correlated with disease severity and body temperature (P <0.05). CONCLUSION: Results of whole body protein metabolism measured with the [15N]glycine single oral dose method in children with MSS and in healthy children were in line with expectations based on results obtained in earlier reports and with different methods.

Bioelectrical impedance measurements in patients with gastrointestinal disease: validation of the spectrum approach and a comparison of different methods for screening for nutritional depletion.

BACKGROUND: Bioelectrical impedance spectroscopy (BIS) may be of value in identifying patients with nutritional depletion. OBJECTIVE: The primary aim of the study was to assess the validity of BIS in patients with gastrointestinal disease. The secondary aim was to compare different screening methods for identifying nutritionally depleted patients. DESIGN: In 70 patients with gastrointestinal disease, BIS measurements were performed and fluid compartments were calculated from extrapolated resistance (R) values of extracellular (R(ECW)) and intracellular (R(ICW)) water based on mixture equations. Results were compared with total body water and ECW, which were measured by dilution methods. Patients were classified as depleted if their actual fat-free mass (FFM) was <90% of their ideal FFM (iFFM). Different screening approaches for depletion were compared: the impedance vector method and the resistance index (RI) in relation to iFFM (RI/iFFM). RESULTS: Total body water and ICW were largely underestimated (4 L) in the not-depleted patients but not in the depleted patients. In both groups, ECW was slightly overestimated (0.6-0.7 L). The critical frequency was 60% higher and the membrane capacitance was 40% lower in the depleted than in the not-depleted patients. The impedance vector method failed to identify depleted patients, whereas the proposed ratio at R(50) (R measured at 50 kHz) and R(inf) (R at infinite frequency) resulted in comparable sensitivity (86%) and specificity (73-80%). CONCLUSIONS: BIS measures of body fluids are influenced by the presence of depletion, probably because of alterations in the electric properties of the body at the cellular level. However, for screening purposes, the use of the ratio (L(2)/R)/iFFM at R(50) and R(inf) may be of value.

Lipid, nitrogen, water and energy content of a single stool sample in healthy children and children with cystic fibrosis.

UNLABELLED: To evaluate the usefulness of "single stool sample" analysis in the investigation of steatorrhoea instead of 72-h stool collection, we examined 57 stool samples of patients with cystic fibrosis (CF) while on pancreatic enzyme therapy and 29 stool samples of healthy children. We compared results of fat, nitrogen, water and energy content. Fat was determined by the method of Van de Kamer et al. and the Acid Steatocrit (AS) method, water by vacuum drying, nitrogen by the Dumas method and energy was obtained using a bomb calorimeter. Results (median) for CF patients and healthy controls were significantly different (P< or =0.0001) for fat respectively: 8.90 and 4.75/100 g wet weight (ww) stool as measured by the method of Van de Kamer et al. and 28.6% and 7.2% by the AS method. Energy results for energy were also significantly (P< or =0.0001) different: 742.96 and 549.32 kJ/100 g ww stool for CF patients and healthy controls respectively. Results of single stool sample water and nitrogen were similar in both groups. These results were comparable to those of a 3-day stool collection, as reported in the literature. CONCLUSION: Results from single stool samples yield clinically useful information concerning fat and energy. Single stool sample analysis is therefore useful for frequent monitoring of faecal fat and energy.

Functional relationship of alpha-glutathione S-transferase and glutathione S-transferase activity in machine-preserved non-heart-beating donor kidneys.

alpha-Glutathione S-transferase (alpha-GST) is a biochemical parameter used to estimate the amount of proximal tubule damage to a kidney. In normal clinical practice, the concentration of alpha-GST in urine is determined by a rather time-consuming immunochemical test, the enzyme-linked immunosorbent assay (ELISA). Kidneys from non-heart-beating (NHB) donors are perfused prior to transplantation. The determination of alpha-GST concentration in the perfusate to monitor damage is also done by means of an ELISA test. However, because this is a time-consuming method, it would be helpful to find a parameter proportional to GST concentrations that would be available within minutes. We therefore compared the method of determining alpha-GST concentration via ELISA with that of determining the enzymatic activity of GST, which is much faster (results available within 10 min). The comparison was made using 150 preserved kidneys that had been perfused for 6 h. The correlation was found to be very good, as indicated by the linear regression data: r=0.954, P<0.001. pi-Glutathione S-transferase (pi-GST) was also determined by means of an ELISA test, and the concentration of pi-GST was compared with the enzymatic activity of the "total" GST. The precision of the enzymatic method, given by intra- and interassay variation, was 1.5% and 10.5%, respectively.

Accuracy of bioelectrical impedance spectroscopy in measuring changes in body composition during severe weight loss.

BACKGROUND: Bioelectrical impedance spectroscopy (BIS) is an attractive method for measuring body composition because it is noninvasive, simple, and cheap. The effect of obesity on the accuracy of impedance measurements has been recognized for some time, but no conclusive explanations or ways to correct the measurement errors have been published. We studied the effect of the composition of weight loss on the accuracy of BIS to measure changes in body fluid volumes during severe weight loss. Within subjects the effect of variable losses of fat mass was studied. METHODS: In 10 morbidly obese female subjects who underwent gastric reduction surgery, changes in total body water (TBW) and extracellular water (ECW) were monitored for 1 year by deuterium (Deu) and bromide (Br) dilution and by BIS. Measurements were performed before the operation and after 2 weeks, 3 months, and 1 year. Extrapolated resistance values of extracellular (Recw) and intracellular water (Ricw) were used in mixture equations for calculating the corresponding fluid volumes. RESULTS: After 1 year, weight decreased by 53 kg, TBW (Deu) loss was 8.7 L, and ECW (Br) loss was 4.3 L. Comparison of BIS with reference methods for measuring all possible changes over 6 time-intervals revealed a mean overestimation of TBW (2.4 L, SD = 2.9) and ECW (0.74 L, SD = 2.6) losses by BIS. Overestimation increased significantly with increasing fat losses, expressed as percentage fat of the weight loss and as change in triceps skinfolds. Measured changes in Recw and Ricw were less than expected for an ideal agreement between dilution methods and mixture equations. CONCLUSIONS: BIS with the use of mixture equations overestimates fluid losses during weight loss. The error is associated with the amount of fat loss. The large contribution of the factor weight in the mixture equations is likely to be responsible. The assumptions of mixture theory are not valid in obesity.