Combination of recombinant human growth hormone and glutamine-enriched total parenteral nutrition to surgical patients: effects on circulating amino acids.

BACKGROUND & AIMS: Both recombinant human growth hormone (rhGH) and glutamine (GLN) may have beneficial anabolic actions on amino acid metabolism. The aim of this study was to evaluate the additive effects of rhGH and GLN on plasma amino acids postoperatively. METHODS: 31 females undergoing laparoscopic cholecystectomy were randomized to three groups: Group I (n=10) received 13 IU/m(2) of rhGH the morning of surgery and the following three postoperative days, together with glutamine-free TPN for the first two postoperative days. Group II (n=11) received rhGH as the first group, together with glutamine-enriched (7 g GLN/m(2)/day) TPN. Group III (n=10) received glutamine-enriched TPN as the second group, but rhGH was replaced by placebo. Daily plasma amino acid concentrations and nitrogen balance were determined. RESULTS: In the GH treated groups, the plasma concentrations of several amino acids were decreased on the third postoperative day, compared to preoperatively. This was not observed in Group III. The changes were more pronounced in Group II. In Group II the negative AV-differences of amino acids tended to be attenuated, while the patients in Group III had increased negative AV-differences. The cumulative nitrogen balance was significantly improved in the GH groups, compared with Group III. CONCLUSION: The combined treatment of growth hormone and glutamine has additive effects on AV-balances of amino acids postoperatively, whereas nitrogen balance is not further improved when adding glutamine to rhGH treatment.

Long-term effects of postoperative total parenteral nutrition supplemented with glycylglutamine on subjective fatigue and muscle protein synthesis.

Seventeen patients undergoing elective open cholecystectomy were given conventional total parenteral nutrition either with (nine patients) or without (eight) glutamine supplementation of 20 g/day for 3 days after surgery and thereafter ordinary food for the following 27 days. Muscle protein synthesis, as assessed by the total concentration of ribosomes, decreased in control patients on day 3 following surgery and remained low on days 10, 20 and 30 (P < 0.05). In patients who received glutamine the total ribosome concentration was maintained on the third day after operation. Concurrently, the subjective feeling of fatigue increased on days 3 and 10 after surgery and the nitrogen balance was negative after operation in both groups, without any difference related to glutamine supplementation. Intravenous glutamine after surgery counteracts a decline in muscle protein synthesis only for as long as it is provided.

Stress hormone and amino acid infusion in healthy volunteers: short-term effects on protein synthesis and amino acid metabolism in skeletal muscle.

To study the immediate effects of stress hormones and intravenous amino acid support, healthy male volunteers were administered a stress-hormone infusion including epinephrine, cortisol, and glucagon either alone (Triple, n = 8) or combined with a balanced glutamine-free amino acid solution (Triple AA, n = 8) over a period of 6 hours. The amino acid infusion was started 2 hours after the hormone infusion. A third group (AA, n = 8) received the balanced amino acid solution alone. After 6 hours of the stress-hormone infusion, a decrease was observed in skeletal muscle protein synthesis as measured by the size distribution and concentration of ribosomes. The decrease was prevented by an infusion of the balanced amino acid solution. Following the triple-hormone infusion, a decrease was noted in the content of the total free amino acids in both muscle and plasma. After including amino acids in the infusion solution, the significant decrease in muscle glutamine caused by the triple hormones was not seen. Plasma cortisol, insulin, and glucose increased in response to the triple-hormone infusion alone or in combination with amino acids. In summary, the results show that the signs of muscle protein catabolism elicited by administration of stress hormones can be attenuated by simultaneous administration of a conventional amino acid solution, although it does not contain glutamine.

Long-term effect of glycyl-glutamine after elective surgery on free amino acids in muscle.

In order to evaluate the long-term effect of total parenteral nutrition supplemented with glutamine after surgery, patients (n = 17) undergoing elective abdominal surgery were randomized into two groups and studied for 30 days after surgery. During the 3 days immediately after surgery, one group (n = 8) was given total parenteral nutrition including a conventional amino acid solution (control group). The other group (n = 9) was given isocaloric and isonitrogenous total parenteral nutrition including the same amino acid solution supplemented with the dipeptide, glycyl-glutamine (GLN group). Oral food intake started on the third postoperative day and was gradually increased at will. The concentration of free amino acids in percutaneous muscle biopsy specimens was determined preoperatively and on days 3, 10, 20, and 30 after the operation. Free glutamine decreased in skeletal muscle in the control group on days 3 and 10 by 32.2 +/- 5.4% (p < .01) and 20.1 +/- 6.9% (p < .05), respectively. In the glycyl-glutamine group, the decrease in glutamine was delayed until day 10 when it was 22.1 +/- 8.1% (p < .05). The glutamine levels were restored on days 20 and 30 in both groups. Total parenteral nutrition supplemented with glutamine maintained the free glutamine levels in skeletal muscle after surgery, but when treatment was discontinued, the glutamine concentration in muscle dropped, despite a normal enteral dietary intake.

Early history of ESPEN.

Since the European Society of Parenteral and Enteral Nutrition (ESPEN) is now well established as a major international scientific organisation, it may be of interest to recall how the Society came to be formed and how it evolved during its first few years. A chronological view will be given of the way ESPEN was organised during the early years, followed by a commentary on the development of its many roles.

Free amino acids in biopsy specimens from the human colonic mucosa.

The content of free amino acids and total protein was determined in endoscopic biopsy specimens from the rectum, descending colon, transverse colon, and ascending colon in 10 patients. The amino acids were quantified by ion-exchange chromatography and were detected by fluorescence. The amino acid pattern and the rank order of the individual amino acids in the colon were different compared to those in plasma. Glutamate, taurine, aspartate, glutamine, glycine, alanine, serine, lysine, valine, and ornithine were the 10 most abundant amino acids in the colon. The rank order was the same in all of the different segments of the colon. The concentrations of the amino acids decreased the more aborally the biopsies were taken. The protein content in the rectum was significantly lower than that in the transverse colon, but there were no difference between the different segments otherwise. The study demonstrated the possibility of determining free amino acids from endoscopic biopsies of human colonic mucosa. Biopsy specimens from the descending colon and/or rectum/sigmoid colon may be considered representative of the entire large intestine. The technique may be used for repeated sampling in studies of the amino acid metabolism of the intestinal mucosa.

Muscle protein synthesis after operation: effects of intravenous nutrition.

OBJECTIVE: To assess the effect of an elective abdominal surgical operation (open cholecystectomy) on the rate of protein synthesis in skeletal muscle in humans. DESIGN: Prospective random control trial. SETTING: University hospital. SUBJECTS: 17 Metabolically healthy patients who were to undergo elective open cholecystectomy. INTERVENTIONS: Patients randomised to receive either saline alone (n = 8) or total parenteral nutrition (n = 9) for three days after operation. The rate of protein synthesis in muscle was calculated from the increase in enrichment of (1-13C) leucine in protein after a flooding dose of (1-13C) leucine. RESULTS: Median (quartiles) rate of protein synthesis had decreased on the third postoperative day in the saline group by 49% (from 2.42 [2.03, 2.54] to 1.24 [0.99, 1.63]) and in the group that had received total parenteral nutrition by 54% (from 1.96 [1.90, 2.07] to 0.91 [0.79, 1.06]) (p < 0.01). CONCLUSIONS: The trauma associated with open cholecystectomy reduced the rate of protein synthesis in skeletal muscle by half in three days, and conventional total parenteral nutrition had no effect on these changes.

Temporal responses of protein synthesis in human skeletal muscle to feeding.

In attempting to evaluate alterations in metabolic responses to dietary nutrients that occur in pathological conditions in man, it is first necessary to understand normal metabolic responses. The present study set out to determine the temporal responses of protein synthesis in the skeletal muscle of healthy subjects to the consumption of food. Sequential measurements of protein synthesis in quadriceps muscle were made in eight subjects by injection of 0.05 g L-[1-13C]leucine/kg body-weight. The rate of protein synthesis after an overnight fast (i.e. in the post-absorptive state) was 2.2% muscle protein. After 1 h of eating, protein synthesis was unaltered (2.2%/d), but after 10 h of consuming small hourly meals the rate had risen to 2.9%/d, with a variation in response among individuals. The response of muscle to 10 h of feeding was also investigated in subjects who underwent only one measurement each, either after 10 h of eating small meals or after the same time-period when no food was given. Protein synthesis rates were only slightly elevated in the group of fed individuals (2.3%/d, n 6) compared with the fasted group (2.1%/d, n 6). Taken together the two studies suggest that in healthy adults muscle protein synthesis does not respond quickly to the influx of dietary nutrients and that even after 10 h of feeding any stimulation of protein synthesis is small.

Biosynthetic human growth hormone preserves both muscle protein synthesis and the decrease in muscle-free glutamine, and improves whole-body nitrogen economy after operation.

As a reproducible human trauma model, patients (n = 17) undergoing elective cholecystectomy were studied for 3 postoperative days. They were randomly allocated to receive either recombinant human growth hormone (hGH; 0.3 U/kg/24 hours) or placebo together with total parenteral nutrition, including 0.2 gN/kg/24 hours and 135 kJ/kg/24 hours. Before operation and on the third postoperative day, percutaneous muscle biopsies were performed to determine the concentration and size distribution of ribosomes and the free amino acid concentrations. The significant postoperative decrease in the total ribosome concentration (15.3 +/- 6.4%) and the polyribosome concentration (20.9 +/- 6.5%) in the control group was impeded in the group receiving synthetic hGH. Muscle free glutamine decreased by 35.6 +/- 4.2% in the control group and to a lesser extent in the group that was given hGH after operation (p less than 0.05). The protein content of skeletal muscle was unchanged. The cumulated nitrogen balance for the study period was negative in the control group (-7.09 +/- 0.71 gN), but was not different from zero in the hGH group (-2.32 +/- 1.66 gN). It is concluded that synthetic hGH administered after operation has beneficial effects on the whole-body nitrogen economy, as indicated by the unchanged capacity for protein synthesis in skeletal muscle, the preserved levels of muscle free glutamine, and improvement in the whole-body nitrogen balance. The effects of hGH on skeletal muscle protein and amino acid metabolism can explain the postoperative nitrogen-sparing effect attributed to hGH.

The impact of leucine infusion on skeletal muscle amino acid and energy metabolism in severely traumatized patients.

The response to trauma is associated with increased energy requirements and net protein breakdown. The branched chain aminoacids, especially leucine, are considered to act by serving as a fuel for muscle tissue and by stimulating synthesis of proteins and controlling protein breakdown. Such results have been obtained mainly from in vitro studies. The present study was designed to evaluate the pharmacological effect of leucine infusion on muscle energy/amino acid metabolism in man after severe multiple trauma. 16 patients were studied and randomly allocated into 2 groups. Group 1 was given fat and 20% glucose while group 2 received 6 g N in form of leucine dissolved in 10% glucose solution and fat. The patients received 40 kcal/kg/24 h over an 8 day period after trauma. Biochemical analyses, muscle biopsies (energy substrates, electrolytes, amino acids), nitrogen balance and 3-methyl histidine excretion in urine were evaluated. Biochemical data revealed a significant increase (p < 0.05) of serum urea in group 2 day 4 and 8 after trauma. Muscle intracellular electrolytes (K(+), Mg(2+)) and energy substrates (ATP, phosphocreatine) showed a similar decrease in both groups. The intracellular muscle amino acids displayed a pattern known to be related to trauma without differences between the groups. The cumulative nitrogen balance 8 days after the injury was -93.5 g N +/- 10.1 (SEM) in group 1 and -73 g N +/- 7.5 in group 2. The 3-methylhistidine excretion was markedly increased similar in both groups. The present study demonstrated no significant pharmacological effect of leucine administration on muscle metabolism, nitrogen balance or 3-methylhistidine excretion in severely traumatized patients. Conventional balanced amino acid solutions are probably optimal to meet the patients actual requirements.

Short-term starvation decreases skeletal muscle protein synthesis rate in man.

The rate of protein synthesis in skeletal muscle was determined in the post-absorptive state and after 3 days of starvation in healthy volunteers. The flooding dose technique employing intravenous injection of (1-13C)leucine (0.05 g kg-1) was used and incorporation of isotope into muscle protein was measured by taking percutaneous biopsies at 0 and 90 min. Blood samples were taken during the incorporation period for assessment of the enrichment of the free amino acid precursor of protein synthesis. The median (25,75 quartiles) rate of muscle protein synthesis after an overnight fast was 2.03 (2.00,2.23) % days-1 when the precursor enrichment was obtained by measurement of the plasma alpha-ketoisocaproate, taken to be representative of muscle free leucine. Repeat measurements in the same subjects after 3 days of total starvation showed a decrease to 1.82 (1.57,2.05) % days-1. Rates calculated on the basis of the plasma leucine as precursor were 5% lower at both times. An interindividual variation in response to starvation was observed, but the median decrease of 13% in the rate of protein synthesis was statistically significant (P less than 0.01).

Free amino acids in plasma and muscle during 24 hours post-operatively--a descriptive study.

Intracellular amino acids in skeletal muscle show a specific concentration pattern on the third post-operative day. The temporal development of these changes has not been clarified. Here the amino acid concentrations in skeletal muscle were studied during the first post-operative day in fourteen patients undergoing elective abdominal surgery. Muscle amino acids were determined pre-operatively, as well as at 12 and 24 h post-operatively. In muscle the concentrations of glutamine and the basic amino acids decreased gradually during the first 24 h after surgery to 79% (P less than 0.001) and 67% (P less than .001) respectively. The sum of the essential amino acids decreased to 73% (P less than 0.001) at 12 h, but thereafter rose to 91% (P less than 0.05) at 24 h. The sum of the BCAA decreased to 84% (P less than 0.05) at 12 h but then increased to 116% (P less than 0.05) at 24 h. The alanine concentration increased to 122% (P less than 0.001) during the first post-operative day. In plasma the alanine concentration increased at 12 h while most other amino acids declined. At 24 h post-operatively the plasma concentrations of all amino acids had returned to normal or showed a tendency towards normalization except for phenylalanine, which increased. At the end of the first post-operative day the concentrations of amino acids in muscle were consistent with the alterations previously observed three days after surgery. The changes in plasma amino acid concentrations only partly reflected those in muscle.

Uncomplicated surgery, but not general anesthesia, decreases muscle protein synthesis.

The impact of anesthesia and surgery on protein metabolism is not well characterized. The single effect of general anesthesia and the combined effects of surgery and general anesthesia on protein synthesis in skeletal muscle were studied in metabolically healthy patients (n = 14) undergoing elective abdominal surgery. The rate of muscle protein synthesis was calculated from the increase in enrichment of [1-13C]leucine in protein during 90 min after an intravenous infusion of [1-13C]leucine (0.05 g/kg, 20 atom percent excess). The 1-13C enrichments of plasma leucine and plasma alpha-ketoisocaproate were used to indicate the enrichment of muscle free leucine. The protein synthesis rate was unaffected by general anesthesia; however, at the end of surgery, a 31.5% decline was seen from 2.19(2.13,2.33)%/24 h before anesthesia to 1.50(1.21,1.77)%/24 h (P less than 0.05) immediately after cholecystectomy while the patients were still under general anesthesia.

Long-term changes in muscle free amino acid levels after elective abdominal surgery.

Characteristic changes in the pattern of muscle free amino acids are seen on the third day after elective surgery. The time course of the restoration to normal levels in uncomplicated cases has not been established before. Seven metabolically healthy patients undergoing cholecystectomy were studied. Muscle biopsy specimens and plasma samples were taken before operation and on days 3, 10, 20 and 30 after surgery. The level of total free amino acids in skeletal muscle decreased and the concentrations of branched chain and aromatic amino acids increased on day 3. The original levels were found to be restored on day 10 after surgery. A decrease in glutamine of 38 per cent (P less than 0.001) was seen on day 3, of 20 per cent (P less than 0.05) on day 10 and of 22 per cent (P less than 0.05) on day 30, compared with preoperative values. These results constitute a baseline for future studies in which the impact of nutritional and pharmacological therapies is to be evaluated beyond the immediate postoperative period.

Effects of insulin on myocardial uptake of branched chain amino acids soon after cardiac operations.

Infusion of insulin-glucose-potassium is used to support the failing heart after cardiac operations. Although the effects on myocardial uptake of carbohydrates and lipids have been described, the effects on myocardial extraction of amino acids are unknown. This study was undertaken to clarify the effect of insulin-glucose-potassium on the pattern of amino acid uptake/release in myocardial and skeletal muscle after coronary operations. The amino acid uptake/release of the heart and of the leg was studied in 18 patients 1 hour after coronary bypass operations. The patients were randomized to treatment with 25 U of fast-acting insulin as a bolus injection followed by a continuous infusion of 1 U/kg body weight for 1 hour, or to serve as control patients. The hyperinsulinemic "clamp" technique was used to keep blood glucose unchanged during the study. In the insulin-treated group, the arterial concentration of 17 of 22 individual amino acids, including the three branched chain amino acids, decreased, the remainder being unchanged. The amino acid uptake/release of the leg was unchanged. The net myocardial uptake of leucine and isoleucine shifted to a no-uptake/no-release in the insulin-treated group, whereas the no-uptake/no-release of tyrosine and phenylalanine turned into a significant release. A positive correlation was observed between arterial concentration and myocardial uptake/release of the three branched chain amino acids. It is suggested that insulin, by lowering the arterial concentration of leucine and isoleucine, inhibited the myocardial uptake of these amino acids. This may have a negative effect on postoperative myocardial protein balance suggested by the release of tyrosine and phenylalanine.