Regional impact of adipose tissue morphology on the metabolic profile in morbid obesity

AIMS/HYPOTHESIS

The aim of this study was to determine whether the mean size of fat cells in either visceral or subcutaneous adipose tissue has an impact on the metabolic and inflammatory profiles in morbid obesity.

METHODS

In 80 morbidly obese women, mean visceral (omental) and subcutaneous fat cell sizes were related to in vivo markers of inflammation, glucose metabolism and lipid metabolism.

RESULTS

Visceral, but not subcutaneous, adipocyte size was significantly associated with plasma apolipoprotein B, total cholesterol, LDL-cholesterol and triacylglycerols (p ranging from 0.002 to 0.015, partial r ranging from 0.3 to 0.4). Subcutaneous, but not visceral, adipocyte size was significantly associated with plasma insulin and glucose, insulin-induced glucose disposal and insulin sensitivity (p ranging from 0.002 to 0.005, partial r ranging from -0.34 to 0.35). The associations were independent of age, BMI, body fat mass or body fat distribution. Adipose tissue hyperplasia (i.e. many small adipocytes) in both regions was significantly associated with better glucose, insulin and lipid profiles compared with adipose hypertrophy (i.e. few large adipocytes) in any or both regions (p ranging from <0.0001 to 0.04). Circulating inflammatory markers were not associated with fat cell size or corresponding gene expression in the fat cell regions examined.

CONCLUSIONS/INTERPRETATION

In morbidly obese women region-specific variations in mean adipocyte size are associated with metabolic complications but not systemic or adipose inflammation. Large fat cells in the visceral region are linked to dyslipidaemia, whereas large subcutaneous adipocytes are important for glucose and insulin abnormalities. Hyperplasia (many small adipocytes) in both adipose regions may be protective against lipid as well as glucose/insulin abnormalities in obesity.

Primary differences in lipolysis between human omental and subcutaneous adipose tissue observed using in vitro differentiated adipocytes

Catecholamine-induced lipolysis is elevated in omental as compared to subcutaneous adipocytes due to primary differences between the two cell types (i.e., they have different progenitor cells). Whether there is regional variation in atrial natriuretic peptide (ANP)-induced lipolysis is unknown. We studied whether beta-adrenoceptor signaling to lipolysis and ANP-induced lipolysis are involved in the primary differences in lipolysis. In vitro experiments on differentiated preadipocytes from human subcutaneous and omental adipose tissue were performed. The cells were kept in culture for a relative long duration, so any influence of local environment and circulation in the various adipose tissue depots could be excluded. Using beta1-, beta2-, and beta3-adenoceptor agonists, lipolysis was found to be significantly higher in omental as compared to subcutaneous differentiated preadipocytes. Forskolin and dibutyryl cAMP, which act at post-adrenoceptor levels, did not show any regional difference. There was no regional difference in ANP-induced lipolysis. Gene expression of beta1- and beta3-adrenoceptors was higher and beta2-adrenoceptor expression was lower in the omental cells. Omental fat cells have an increased beta-adrenoceptor-mediated lipolysis principally due to primary differences in the early event that couples beta-adrenoceptor subtypes to G-proteins. ANP-induced lipolysis is not subject to primary regional variation.

Prospective and controlled studies of the actions of insulin and catecholamine in fat cells of obese women following weight reduction

AIMS/HYPOTHESIS

Enlarged fat cells from obese subjects are characterised by insulin resistance and abnormal adrenergic regulation of lipolysis. The aim of the present study was to examine whether these aberrations return to normal following weight reduction.

MATERIALS AND METHODS

Obese women (n=25) were investigated before and 3+/-1 years (mean+/-SD) after steady-state weight reduction and compared with control women who were matched to the cases at re-examination in terms of age and BMI. Adipocyte volume, lipogenesis and lipolysis were determined in isolated subcutaneous fat cells following stimulation or inhibition at different steps of the lipolytic cascade.

RESULTS

Weight reduction decreased fat cell volume and basal and adrenergic-regulated lipolysis rates to values that were 20-40% lower than those in control women (p=0.0002-0.03), despite the fact that percentage body fat was almost identical in the two groups of women. Fat cell volume was directly proportional to lipolysis in obese subjects, both before and after weight reduction, and in control subjects. Insulin-induced antilipolysis and lipogenesis were completely normalised after weight reduction.

CONCLUSIONS/INTERPRETATION

Body-weight-reduced obese women had low basal and catecholamine-stimulated adipocyte lipolysis, presumably due to adipose tissue hyperplasia. This could make an important contribution to body weight gain following weight loss. Adipocyte insulin resistance is secondary to obesity.

Effect of testosterone on lipolysis in human pre-adipocytes from different fat depots

AIM/HYPOTHESIS

Regional differences in lipolysis, with higher lipolytic activity in visceral than subcutaneous fat, are important for the development of insulin resistance and might be influenced by testosterone.

METHODS

We studied testosterone-regulated lipolysis and protein expression (by western blot) in fully differentiated pre-adipocytes from visceral (omental) and abdominal subcutaneous adipose tissue from 52 human subjects. These cells were isolated and cultured in a serum-free medium.

RESULTS

Testosterone caused a specific, time- and concentration-dependent 50% reduction of catecholamine-stimulated lipolysis in the subcutaneous depot. Half of the maximum effect occurred at 10 nmol/l. The inhibitory effect was due to the inability of beta-adrenoceptors and cyclic AMP to stimulate the protein kinase A, hormone-sensitive lipase complex. Testosterone caused a depot-specific 50% reduction of the protein expression of hormone-sensitive lipase and beta(2)-adrenoceptors in differentiated subcutaneous pre-adipocytes, but no change in beta(1)-adrenoceptors, protein kinase A subunits or perilipin expression. In contrast, testosterone had no effect on lipolysis or protein expression in the visceral depot. However, testosterone receptors were present in both depots, and the hormone inhibited adipocyte leptin secretion. Similar effects on lipolysis were observed with dihydrotestosterone.

CONCLUSIONS/INTERPRETATION

Testosterone in physiological concentrations causes a depot-specific reduction of catecholamine-stimulated lipolysis in subcutaneous fat cells, probably due to reduced protein expression of beta(2)-adrenoceptors and hormone-sensitive lipase. This could be an important pathogenic factor underlying regional differences in lipolysis and development of insulin resistance and hyperandrogenic polycystic ovary syndrome.

Augmented increase in tight junction permeability by luminal stimuli in the non-inflamed ileum of Crohn's disease

BACKGROUND

Crohn's disease is associated with deranged intestinal permeability in vivo, suggesting dysfunction of tight junctions. The luminal contents are important for development of neoinflammation following resection. Regulation of tight junctions by luminal factors has not previously been studied in Crohn's disease.

AIMS

The aim of the study was to investigate the effects of a luminal stimulus, known to affect tight junctions, on the distal ileum in patients with Crohn's disease.

PATIENTS

Surgical specimens from the distal ileum of patients with Crohn's disease (n=12) were studied, and ileal specimens from colon cancer patients (n=13) served as controls.

METHODS

Mucosal permeability to 51Cr-EDTA and electrical resistance were studied in Ussing chambers during luminal exposure to sodium caprate (a constituent of milk fat, affecting tight junctions) or to buffer only. The mechanisms involved were studied by mucosal ATP levels, and by electron and confocal microscopy.

RESULTS

Baseline permeability was the same in non-inflamed ileum of Crohn's disease and controls. Sodium caprate induced a rapid increase in paracellular permeability--that is, increased permeation of 51Cr-EDTA and decreased electrical resistance--which was more pronounced in non-inflamed ileum of Crohn's disease, and electron microscopy showed dilatations within the tight junctions. Moreover, sodium caprate induced disassembly of perijunctional filamentous actin was more pronounced in Crohn's disease mucosa. Mucosal permeability changes were accompanied by mitochondrial swelling and a fall in epithelial ATP content, suggesting uncoupling of oxidative phosphorylation.

CONCLUSIONS

The tight junctions in the non-inflamed distal ileum of Crohn's disease were more reactive to luminal stimuli, possibly mediated via disturbed cytoskeletal contractility. This could contribute to the development of mucosal neoinflammation in Crohn's disease.

Bidirectional supply of glutamine maintains enterocyte ATP content in the in vitro using chamber model

Glutamine is the principal energy source for enterocytes, but it is not known whether parenteral or enteral supplementation is most beneficial to gut integrity. The aim of this study was to evaluate the effects of glutamine in uni- or bidirectional supply on the viability of intestinal mucosa of starved rats during incubation in Ussing chambers. Segments of jejunum from rats starved for 48 h were randomly mounted in Ussing chambers with three nutrient solutions: Krebs buffer without glutamine; 6 mM glutamine added to the mucosal side; 6 mM glutamine added to the mucosal side and 0.6 mM glutamine to the serosal side. ATP content of the mucosa, electrophysiology, and 51Cr-ethylenediaminetetraacetate (EDTA) permeability were studied during 180 min of incubation. The addition of glutamine to both sides of the stripped mucosa improved ATP levels compared to the Krebs solution (P < 0.05), and the addition of glutamine resulted in an increase in short circuit current (P < 0.05). No significant differences were seen in 51Cr-EDTA permeability or epithelial electrical resistance. Glutamine supplementation to both the luminal and serosal side in the Ussing chamber was more effective than luminal glutamine only in maintaining ATP levels of intestinal mucosa. Bidirectional supplementation of glutamine might improve intestinal energy metabolism and viability in in vitro studies.

No effect of bolus glutamine supplementation on the postresectional adaptation of small bowel mucosa in rats receiving chow ad libitum

OBJECTIVE

Early postoperative enteral feeding has been reported to stimulate intestinal mucosa proliferation. Dietary components influence the intestinal adaptive response after resection and glutamine is a preferential nutrient to enterocytes. The purpose of this study was to evaluate the effects of bolus glutamine supplementation on intestinal adaptation.

METHODS

Male Wistar rats underwent a 65% small bowel resection. The rats were divided into three groups receiving glutamine 2 g/kg/day, isonitrogenous glycine or saline by gavage for 10 days. All the rats were provided with ordinary rat chow ad libitum. Sampling was done 10 days after resection. Animals fed ordinary rat chow without surgery or specific treatment served as control.

RESULTS

Mucosal wet weight, DNA, RNA, protein contents and sucrose activity, as well as villus height increased in the ileal remnant. No significant differences in any of these parameters or body weight could be found between the three groups.

CONCLUSION

Postoperative enteral bolus glutamine supplementation at a dose of 2 g/kg b.w. did not enhance the adaptation of the residual intestine 10 days after massive intestinal resection in the rat.

Early gastrointestinal regulatory peptide response to intestinal resection in the rat is stimulated by enteral glutamine supplementation

BACKGROUND

Intestinal resection stimulates the synthesis and release of gastrointestinal peptides that regulate the growth and adaptation of the mucosa. Luminal nutrients are necessary for optimal proliferation and glutamine is the preferential nutrient to the small bowel. The interplay between glutamine and regulatory peptides could be important in treating short bowel syndrome.

METHODS

63 Sprague-Dawley rats were divided into 3 groups: resection; transection, or controls. After intestinal resection animals were orally fed either a diet without glutamine or a glutamine-supplemented diet for 2 days. Transected animals and controls without prior surgery were fed the same two diets. Epidermal growth factor (EGF), transforming growth factor-alpha, insulin-like growth factors I and II (IGF-I and IGF-II), peptide YY (PYY), and enteroglucagon were analyzed in mucosa from the proximal jejunum, distal ileum as well as in portal plasma when the animals were euthanized 72 h after surgery.

RESULTS

Intestinal resection resulted in an early increase in portal plasma concentrations of PYY, EGF, enteroglucagon, and mucosal IGF-II and EGF content that were significant in glutamine-treated animals. Glutamine significantly increased PYY in portal blood after resection (p < 0.05).

CONCLUSION

Glutamine could be of importance for the functional adaptation of residual small bowel mucosa by increasing PYY release.

Laparoscopic hernia repair in patients with bilateral groin hernias

OBJECTIVE

To compare outcome of unilateral and bilateral laparoscopic hernia repair.

DESIGN

Prospective consecutive trial.

SETTING

University hospital, Sweden.

SUBJECTS

380 patients who had unilateral hernias repaired laparoscopically and 64 patients who had bilateral hernias repaired. The median (range) age in the two groups was 56 (21-86) and 61 (30-85) years, respectively and the median (range) follow-up was 42 (24-58) months.

MAIN OUTCOME MEASURES

Operating time, hospital stay, complications, and time to recovery.

RESULTS

The median (range) operating time was 70 (25-240) minutes in the unilateral and in the bilateral group 113 (55-330) minutes. The complication rate, recurrence rate, and time to full recovery did not differ between the groups.

CONCLUSION

The laparoscopic approach seems to be a good option for patients with bilateral inguinal hernias.

Glutamine effects on permeability and ATP content of jejunal mucosa in starved rats

INTRODUCTION

Starvation induces an increase in intestinal permeability that can be of importance to intestinal integrity. Glutamine is the principal energy source for intestinal enterocytes and is considered essential for gut metabolism, structure and function. The aim of this study was to investigate whether glutamine could improve the ATP content of the mucosa of starved rats and attenuate the permeability perturbation during incubation in vitro in Ussing chamber.

METHODS

Segments of jejunum from rats starved for 48 h were mounted in Ussing chambers. Glutamine was added to Krebs-buffer at 0.6mM, 3mM, 6mM and 30mM concentrations on the mucosal side. Cr-EDTA permeation, ATP content of the epithelium mucosa and electrophysiology were studied during 180 min of incubation in Ussing chambers.

RESULT

These was a negative linear correlation between ATP content and(51)Cr-EDTA permeability in stripped mucosa. ATP content was reduced in all groups during the experiment. When 30 mM glutamine was added on the mucosal side there was an increase in(51)Cr-EDTA permeability (P< 0.001). There was no effect of glutamine on transepithelial resistance but higher concentrations of glutamine (>3mM) significantly increased the short circuit current.

CONCLUSION

Supplementing glutamine to the mucosal side in the Ussing chamber led to an increase in ion pump activity and to an increase in paracellular permeability at the 30mM glutamine concentration. Glutamine did not restore the intracellular ATP level. The increase in permeability was inversely correlated to the mucosal ATP content.

Whole-protein-based enteral formula stimulates intestinal ornithine decarboxylase activity more than single amino acids but does not affect mucosal adenosine triphosphate content in early postsurgical refeeding

BACKGROUND

To restore intestinal integrity after starvation and trauma, luminal nutrients are essential. Specific nutrients such as glutamine support mucosal proliferation and energy metabolism. The aim of this study was to compare effects of enteral formula vs specific amino acids on ornithine decarboxylase (ODC) activity and adenine nucleotide metabolism in jejunal mucosa.

METHODS

Male Wistar rats (240 to 280 g) were starved for 48 hours and subjected to intestinal transection, gastrotomy, and jejunal instillation of 5mL nutrient solution. In the first experiment, standard enteral formula (EF) was compared with isonitrogenous formula supplemented with the glutamine precursor, alpha-ketoglutarate (alpha-KG). In a second experiment, 2% glutamine was compared with isonitrogenous ornithine alpha-KG, arginine alpha-KG, glycine and diluted standard enteral formula (EF), or saline. The ODC activity, adenosine triphosphates (ATP), and RNA and protein in the jejunal mucosa were analyzed 2 hours after surgery.

RESULTS

The ODC peak in jejunal mucosa in animals treated with EF was higher than when supplemented with alpha-KG (p < .05). Compared with specific amino compounds, EF resulted in a significantly higher ODC peak and no differences were seen between the different specific amino acids. Differences seen in ATP or energy charge between the groups were not significant.

CONCLUSIONS

Immediate postoperative enteral feeding by standard EF results in rapid increase of ODC activity. This response was attenuated when the enteral nutrition was supplemented with alpha-KG and was absent when isonitrogenous single amino acids were administered. We found no significant effects on ATP content in the small bowel mucosa by supplementing the diet with alpha-KG.

Cost-minimisation analysis of laparoscopic and open appendicectomy

OBJECTIVE

To compare the direct and indirect costs of laparoscopic and open appendicectomy.

DESIGN

Randomised study.

SETTING

University hospital, Sweden.

MAIN OUTCOME MEASURES

Total costs for a defined period of time for each option.

RESULTS

102 patients were randomised and 99 were included in the final analysis. All patients had completely recovered within two months of operation. Disposable extra material used for the laparoscopic operation and longer operating time raised its median cost by SEK 912 and 1785, respectively. The mean duration of hospital stay, period off work (indirect costs), and time to complete recovery did not differ between the groups.

CONCLUSION

Laparoscopic appendicectomy has higher direct costs than open operation and is not as cost-effective when the longterm outcome is the same in both groups.

Effects of starvation and bowel resection on paracellular permeability in rat small-bowel mucosa in vitro

BACKGROUND

Maintenance of intestinal integrity is essential after major abdominal surgery in malnourished subjects. The purpose of this experimental study was to investigate factors affecting small-bowel mucosa permeability in vitro in the immediate postoperative period in starved rats.

METHODS

Male Wistar rats were randomly placed in five groups: Controls, Anesthesia, Resection, Starvation, and Starvation + resection. Controls consisted of fed rats. Anesthesia was induced intraperitoneally with xylazine and ketamine. Resection was 5 cm of the mid-jejunum, and the starvation period was 48 h. Two hours after surgery stripped mucosal segments from the jejunum and the ileum were mounted in Ussing chambers, and the transmucosal permeation of 51Cr-labeled ethylenediaminetetraacetic acid (EDTA) and dextran (40,000 Da) was studied for 120 min while electrophysiology was monitored.

RESULTS

Starvation increased permeability to 51Cr-EDTA in both the jejunum and ileum. In the jejunum permeability was further increased by starvation + resection. Resection or anesthesia alone did not increase permeability. The villous height in the jejunum was reduced by starvation. Mucosal permeability was correlated to the change in transepithelial resistance during experiments.

CONCLUSIONS

Starvation was the main cause of increased mucosal permeability in both intestinal segments of the rat, but surgical trauma had an additive effect, which was most pronounced in the jejunum.

Early response of ornithine decarboxylase activity and energy metabolism to postsurgery refeeding in rat small intestine

INTRODUCTION

Enterocyte proliferation and cellular energy status are important to intestinal integrity after starvation and trauma. The proliferative response to nutrients is expressed in the activity of ornithine decarboxylase (ODC), but ODC activity and ATP level in the intestinal mucosa the first hours after surgery and immediate refeeding are not known.

METHODS

Male Wistar rats (240-280 g) were starved for 48 h and submitted to laparotomy with distal ileal transection, gastrostomy and jejunal instillation of either enteral formula or saline. The ODC activity and ATP content of the jejunal mucosa were analysed in samples taken at 1, 2, 4 and 6 h after surgery.

RESULTS

ODC activity increased and reached the highest peak at 2 h in the refed animals. ATP concentration and energy charge of jejunal mucosa were significantly reduced 6 h after surgery compared to initial levels, but there were no differences between animals that were refed or not. Intestinal transection did not stimulate ODC activity.

CONCLUSION

ATP levels in intestinal mucosa decreased after surgery, and early enteral feeding did not seem to prevent this decrease during the first 6 h. Refeeding immediately after surgery elicits an early but transient increase of ODC activity in rat jejunal mucosa.

The role of glutamine, serum and energy factors in growth of enterocyte-like cell lines

BACKGROUND

Glutamine is routinely added to most cell cultures. Glutamine has been found to be the preferential nutrient to the rapidly replicating intestinal mucosa, but whether this is a metabolic effect or due to other properties of this amino acid is not determined. To study the importance of glutamine on the growth of two enterocyte-like cell lines, the effects of depriving the media or supplementing it with glutamine were assessed in media with different serum and energy supplements.

METHODS

CaCo-2 and HT-29 cells were grown in serum-free medium, with fetal bovine or synthetic serum, and with or without glucose or galactose. The glutamine content was varied between 0 and 4 mM. All growth assays were performed in triplicate by counting in a hemocytometer.

RESULTS

Both cell lines were dependent of serum factors for growth, but displayed distinct requirements on glutamine supplementation. Glutamine was an obligate supplement with dose-dependent correlation to growth (r = 0.87, p < 0.01) for CaCo-2 cells cultured in synthetic, but not in fetal bovine serum. In HT-29 cells, the correlation between glutamine and growth was significant (r = 0.68, p < 0.05) only in fetal bovine serum in the absence of galactose.

CONCLUSION

This study shows that glutamine has different growth stimulating effects on two enterocyte-like cell lines studied. This could reflect different modes of action of glutamine on proliferation and differentiation in an enterocyte cell population.

An increase in mucosal insulin-like growth factor II content in postresectional rat intestine suggests autocrine or paracrine growth stimulation

BACKGROUND

Luminal nutrients and growth factors regulate postresectional intestinal growth. The interplay between glutamine and regulatory gastrointestinal peptides is not known.

METHODS

The effects of intestinal resection on tissue and plasma concentrations of peptides were studied in 60 Sprague-Dawley rats divided into resected, transected, or unoperated groups. Subgroups were fed either a glutamine-free or a glutamine-supplemented diet for 7 days. Epidermal growth factor, transforming growth factor-alpha, insulin-like growth factors (IGF) I and II, peptide YY (PYY), and enteroglucagon were analyzed in intestinal mucosa and in portal plasma by radioimmunoassay.

RESULTS

No glutamine-specific effects were seen. The mucosal content of IGF-II (P < 0.01) and the portal levels of enteroglucagon and PYY (P < 0.05-0.01) increased after intestinal resection.

CONCLUSIONS

The increase in PYY and enteroglucagon in portal blood supports a hormonal role in the postresectional adaptation. The increase in IGF II in the ileal mucosa, without changes in plasma, implies autocrine or paracrine growth stimulation at this stage after resection.

Effects of graded glutamine intake on liver protein metabolism following partial hepatectomy

OBJECTIVE

To elucidate whether glutamine can influence the rate of regeneration and protein metabolism in regenerating liver.

DESIGN

Liver regeneration rate, protein content and synthesis were measured in rats 7 days after a liver resection or sham operation. After the operation, the rats were fed three elementary isonitrogenous diets, one without and two including different levels of glutamine.

METHODS

Fifty-six rats were randomly assigned to either sham operation or liver resection. After the operation, they received an isonitrogenous, isocaloric elementary diet with a glutamine content of 0, 2 or 4%. The resected part of the liver was weighed and analysed for DNA and protein content. Seven days later, hepatic protein synthesis was measured by the flooding method using L-[3H]-phenylalanine, and the liver was analysed for DNA, RNA and protein content.

RESULTS

The regeneration rate was higher in the group receiving 2% glutamine but not in the group receiving 4% glutamine than in the 0% group. Total protein content was increased in regenerating liver in the 2 and 4% glutamine groups compared with the 0% group. Protein synthesis was higher 7 days after liver resection than in sham-operated rats. In the 2% group there was a tendency towards increased protein synthesis compared with the 0% group.

CONCLUSION

A diet with normal glutamine content improved liver regeneration rate, total protein content and protein synthesis in regenerating liver, but an excess of glutamine did not enhance this effect.

The effects of a new amino-acid dipeptide solution on nitrogen balance and humoral growth factors in the postoperative state in man

27 patients admitted for elective abdominal surgery were allocated to receive postoperative total parenteral nutrition supplemented with glutamine (glycyl-glutamine) and tyrosine (glycyl-tyrosine) containing dipeptides (DP-Gln 20; 0.16 g glutamine/kg BW/24 h) or isonitrogenous Vamin 18 for 5 days. The aim was to evaluate safety and effects on short-life plasma proteins, nitrogen balance, 3-methylhistidine excretion and alimentary growth factors in plasma. No differences in transthyretin or retinol binding protein levels, nitrogen balance or 3-methylhistidine excretion were found in patients receiving DP-Gln 20 compared to Vamin 18. There were higher plasma levels of peptide YY in the dipeptide group 5 days after surgery (p < 0.05). A correlation between insulin levels and nitrogen balance was found only in DP-Gln 20 treated patients day 6 (r = 0.91, p < 0.01). DP-Gln 20 is a glutamine dipeptide (Gly-Gln) containing amino acid solution which is considered safe in the postoperative state in man. No beneficial effects on whole body protein metabolism were found by adding DP-Gln 20 to total parenteral nutrition.

Enteral glutamine increases growth and absorptive capacity of intestinal mucosa in the malnourished rat

BACKGROUND

Glutamine is an important nutrient for the small intestine. Beneficial effects of glutamine could be related to restoration of optimal intestinal barrier functions.

METHODS

Thirty-eight Sprague-Dawley rats were allocated to three main groups. Experimental groups (n = 22) were malnourished and laparotomized. Sham groups (n = 11) were laparotomized without prior malnutrition. These groups were refed with or without oral glutamine for 3 days. The control group (n = 5) was given chow. Permeability was assessed by the 6-h urinary recovery of orally given polyethylene glycols, PEG 400/1000. Mucosal proliferation was estimated by DNA content and 1-h incorporation of 3H-thymidine intravenously.

RESULTS

In the malnourished groups glutamine resulted in higher thymidine incorporation (p < 0.05) and better absorption of small PEG molecules (p < 0.05).

CONCLUSION

The effects of oral glutamine on permeability after malnourishment and laparotomy are proposed to be related to an increase in absorptive area.

Protein synthesis in regenerating rat liver during malnutrition

To examine the effect of malnutrition on liver protein metabolism and synthesis during liver regeneration, 104 rats were allocated to semi-starvation or ordinary food intake for 1 week. Half of each group was sham operated and the other half was partially hepatectomized. Specimens were taken from the liver at the time of liver resection and from animals killed 24, 48 and 72 h after the primary operation. Liver samples were analysed for DNA and protein, and in the 48-h groups RNA and protein synthesis were also analysed. Protein synthesis was measured by the flooding method using L[4-3H] phenylalanine. The liver weight during regeneration increased very rapidly in the well-nourished animals, but when expressed as percent of body weight or as proportional increases, the difference between well-nourished and malnourished animals disappeared. The fractional rate of protein synthesis was not changed in sham-operated malnourished or well-nourished animals. During regeneration, protein synthesis in well-nourished animals was elevated compared to sham-operated controls, but a lesser stimulation was seen in malnourished rats. It was concluded that the mechanism of liver regeneration depends on nutritional state, involving an increase in protein synthesis in well-nourished animals, but relying more on a decrease in protein degradation or cessation of secretory protein synthesis in malnourished animals.

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.