Anabolic therapy with growth hormone accelerates protein gain in surgical patients requiring nutritional rehabilitation

Systemic and splanchnic metabolic response to exogenous human growth hormone

BACKGROUND

Evidence exists indicating that growth hormone (GH) resistance in some disease states such as hypercatabolic conditions may limit the metabolic benefit associated with recombinant human growth hormone (rhGH) administration. It was the purpose of this study to compare the systemic and splanchnic effects of rhGH in patients with sepsis exhibiting systemic inflammatory response syndrome (SIRS) with the response observed in normal volunteers. Because insulin-like growth factor I (IGF-I) is believed to be the dominant factor responsible for the anabolic effects of rhGH, particular attention was given to this secondary effector.

METHODS

The systemic and splanchnic effects of rhGH (0.15 mg/kg/day) were studied in normal volunteers (n = 5), critically ill patients with sepsis exhibiting SIRS (n = 6), and patients with sepsis exhibiting SIRS while receiving total parenteral nutrition (n = 6). Basal and end study IGF-I, urinary urea excretion, hepatic blood flow, hepatic venous oxygen content, and splanchnic oxygen exchange were measured after a 48-hour course of rhGH.

RESULTS

Fasting basal IGF-I concentrations were reduced by 75% to 83% in patients with sepsis/SIRS relative to normal control subjects. After 48 hours of rhGH, peak IGF-I concentrations were 74% and 76% lower in patients in the Sepsis/SIRS and Sepsis/SIRS + Nutrition groups, respectively, compared with normal control subjects. Despite the attenuated IGF-I rise in patients, urea excretion declined by a similar magnitude in all three groups. Hepatic blood flow remained unaffected, but rhGH administration increased splanchnic oxygen consumption in all groups (control, +57%*; Sepsis/SIRS, +13%; Sepsis/SIRS + Nutr +42%*; *p < 0.05 relative to corresponding basal) resulting in a decline of basal to end therapy hepatic venous oxygen saturation (control, 67 +/- 4% to 62 +/- 11%; Sepsis/SIRS, 51% +/- 14% to 43% +/- 14%*; Sepsis/SIRS + Nutr, 62% +/- 11% to 55% +/- 16%; *p < 0.05 relative to corresponding control value), suggesting that rhGH may induce centrilobular hepatic hypoxia, which may contribute to the diminished IGF-I response.

CONCLUSIONS

Although critically ill patients exhibit an IGF-I increase in response to exogenous rhGH, the rise is markedly attenuated compared with healthy volunteers, indicating the presence of GH resistance. Unexpectedly, the changes in the anabolic hormone IGF-I did not appear to be related to the reduction in urea excretion. This may provide some additional evidence for IGF-I resistance. Finally, rhGH is associated with an augmented splanchnic oxygen consumption but no corresponding increase in regional blood flow. As a result, regional tissue hypoxia may arise and contribute to the impaired or suboptimal IGF-I response pattern.

Growth hormone improves the resistance of thermally injured mice infected with herpes simplex virus type 1

BACKGROUND

Growth hormone (GH) has been shown to promote wound healing and to improve protein metabolism in burned patients. Through immunomodulation, GH has also protected rats infected with Salmonella typhimurium and mice infected with Escherichia coli. In spite of advances in the management of patient care for those with thermal injuries, high mortality rates of burned patients as a result of infections are of special concern. An improvement in the resistance of burned patients to certain infections will make the beneficial role of GH very clear. In this study, therefore, the immunomodulating effects of recombinant human GH (rhGH) in thermally injured mice exposed to opportunistic herpesvirus infections were investigated.

METHODS

(1) Burned mice, exposed to herpes simplex virus type 1 (HSV-1), were treated subcutaneously with rhGH (4 mg/kg) and observed for 21 days to determine the protective antiviral effect of rhGH. (2) Because of reports describing a lack of interferon-gamma (IFN-gamma) responsiveness in burned mice, the IFN-gamma-producing ability of the splenic mononuclear cells (SMNC) from burned mice treated with rhGH was examined. (3) Because the generation of burn-associated suppressor macrophages that can inhibit the IFN-gamma production by SMNC has been previously described, the suppressor cell activities of macrophages from burned mice treated with rhGH were examined.

RESULTS

After exposure to lethal amounts of HSV-1, mice treated with rhGH displayed a reduced mortality rate compared with control mice treated with saline. SMNC from burned mice treated with rhGH produced IFN-gamma, whereas this cytokine was not produced by SMNC from burned mice treated with saline. Also, an inhibition of the generation of burn-associated suppressor macrophages was displayed in burned mice treated with rhGH.

CONCLUSION

Exogenous administration of rhGH caused an improvement in the resistance of burned mice to HSV-1 infection. In burned mice treated with rhGH, the impaired IFN-gamma responsiveness was restored and the generation of burn-associated suppressor macrophages was inhibited. IFN-gamma, a typical antiviral cytokine induced by rhGH through the regulation of the suppressor macrophage generation, may therefore play a role in the protection of burned mice infected with a lethal amount of HSV-1.

Low IGF-I levels are often uncoupled with elevated GH levels in catabolic conditions

Increased GH together with decreased IGF-I levels pointing to peripheral GH insensitivity in critically ill patients have been reported by some but not by other authors. To clarify whether elevated GH levels are coupled with low IGF-I levels in all catabolic conditions, basal GH and IGF-I levels were evaluated in patients with sepsis (SEP, no.=13; age [mean+/-SE]=59.2+/-1.2 yr), trauma (TRA, no.=16; age=42.3+/-3.4 yr), major burn (BUR, no.=26; age=52.8+/-4.2 yr) and post-surgical patients (SUR, no.=11; age=55.0+/-4.7 yr) 72 hours after ICU admission or after cardiac surgery. GH and IGF-I levels were also evaluated in normal subjects (NS, no.=75; age=44.0+/-1.5 yr), in adult hypopituitaric patients with severe GH deficiency (GHD, no.=54; age=44.8+/-2.3 yr), in patients with liver cirrhosis (LC, no.=12; age=50.4+/-2.8 yr) and in patients with anorexia nervosa (AN, no.=19; age=18.7+/-0.8 yr). Basal IGF-I and GH levels in GHD were lower than in NS (68.6+/-6.4 vs 200.9+/-8.7 microg/l and 0.3+/-0.1 vs 1.4+/-0.2 microg/l; p<0.01). On the other hand, AN and LC showed IGF-I levels (70.4+/-9.1 and 52.4+/-10.5 microg/l) similar to those in GHD while GH levels (10.0+/-2.8 and 7.9+/-2.1 microg/l) were higher than those in NS (p<0.01). IGF-I levels in SEP (84.5+/-8.8 microg/l) were similar to those in GHD, AN and LC and lower than those in NS (p<0.01). IGF-I levels in BUR (105.2+/-10.9 microg/l) were lower than in NS (p<0.01) but higher than those in GHD, AN, LC and SEP (p<0.01). On the other hand, in TRA (162.8+/-17.4 microg/l) and SUR (135.0+/-20.7 microg/l) IGF-I levels were lower but not significantly different from those in NS and clearly higher than those in GHD, AN, LC, SEP and BUR. Basal GH levels in SEP (0.6+/-0.2 microg/l), TRA (1.8+/-0.5 microg/l), SUR (2.2+/-0.5 microg/l) and BUR (2.2+/-0.5 microg/l) were similar to those in NS, higher (p<0.05) than those in GHD and lower (p<0.01) than those in AN and LC. In conclusion, our data demonstrate that low IGF-I levels are not always coupled with elevated GH levels in all catabolic conditions. Differently from cirrhotic and anorectic patients, in burned and septic patients GH levels are not elevated in spite of very low IGF-I levels similar to those in panhypopituitaric GHD patients. These findings suggest that in some catabolic conditions peripheral GH insensitivity and somatotrope insufficiency could be concomitantly present.

Fluid and sodium problems in perioperative feeding: what further studies need to be done?

Total parenteral nutrition may induce harmful water and sodium retention. Few efforts have been made to elucidate the mechanisms of this deleterious response to total parenteral nutrition. In this review we discuss the different factors involved in its pathophysiology and possible changes in total parenteral nutrition regimes in order to modulate such a response: reduction of the proportion of non-protein calories given as glucose, restriction of water and sodium, and the possible benefits of pharmaceutical nutritional therapy with glutamine and growth hormone.

Therapeutic options for HIV-associated bodyweight loss. A risk-benefit analysis

Involuntary bodyweight loss, a common complication of infection with HIV, is an indicator of poor prognosis and decreased survival. Because of the multifactorial pathogenesis of HIV-related wasting, emerging therapies are directed at the multiple proposed mechanisms of involuntary bodyweight loss. The initial evaluation and treatment of HIV-related bodyweight loss is focused on the identification and treatment of reversible causes of bodyweight loss, such as secondary opportunistic infections or endocrine dysfunction. Nutritional intervention should begin in the early stages of HIV infection and continue throughout the life of the patient. Of the appetite stimulants, megestrol most consistently promotes bodyweight gain, but with a predominance of fat, not lean, body mass. Anabolic therapies such as testosterone derivatives and recombinant human growth hormone (somatropin) stimulate the addition of lean body mass and are begin actively researched for the treatment of HIV-associated wasting. Finally, thalidomide, a potent inhibitor of tumour necrosis factor-alpha, is a potentially useful therapy that is still under investigation. New research into the treatment of HIV-related bodyweight loss is focusing on combination therapies.

Epidermal growth factor and human growth hormone accelerate adaptation after massive enterectomy in an additive, nutrient-dependent, and site-specific fashion

BACKGROUND

After massive enterectomy (ME), remnant intestine undergoes compensatory adaptation. Epidermal growth factor (EGF) and human growth hormone (hGH) have each been shown to enhance total length small intestine nutrient transport after ME. This study aims to determine the differential effects of EGF and hGH on proximal and distal small intestinal remnants after ME.

METHODS

New Zealand white rabbits underwent 70% mid-jejunoileal resection. After 1 week, animals received hGH (0.2 mg/kg/day), EGF (1.5 micrograms/kg/hr), hGH + EGF, or vehicle (equal volume) for 7 days. Sodium-dependent uptake of glucose, glutamine, alanine, leucine, and arginine into brush border membrane vesicles was quantitated. Serum insulin-like growth factor-I concentrations as well as proximal and distal villus and microvillus heights were measured. IGF binding protein-3 and -4 mRNA expression was determined in full-thickness proximal and distal gut remnants.

RESULTS

Concomitant hGH and EGF treatment up-regulates glucose (100%), glutamine (80%), and leucine (60%) transport in the proximal remnant; alanine (150%) and arginine (400%) transport in the distal remnant; and microvillus height (25% to 35%) both proximally and distally. Serum IGF-I levels and gross villus heights were not different among groups.

CONCLUSIONS

Co-infusion of hGH and EGF accelerates intestinal adaptation after ME in an additive, nutrient-dependent, and site-specific fashion via enhanced nutrient transport as well as microvillus hypertrophy.

Plasma insulin-like growth factor I and IGF binding protein 3 levels in patients with acute cerebral ischemic injury

BACKGROUND AND PURPOSE

The insulin-like growth factors (IGF) are synthesized in the brain and are involved in fetal brain development. An increased expression of IGF-I and IGF-II occurs in cerebral regions with neuronal damage after experimental hypoxic injury. Furthermore, the expression of mRNAs coding for IGF-I and the binding proteins IGFBP-2 and IGFBP-3 is augmented in response to unilateral ischemia in animal models. The secretory dynamics of IGF-I in human cerebral ischemia have not yet been investigated.

METHODS

Plasma IGF-I and IGFBP-3 were measured sequentially in 20 patients with acute ischemic stroke (within 24 hours and 3, 5, and 10 days thereafter). For analysis the patients were assigned to three groups according to the diameter of the infarct area as measured on CT scan: small (< 1.5 cm), moderate (> or = 1.5 cm and < or = 5 cm), and large (> 5 cm). Eight age-matched patients with nonvascular, neurological illnesses served as controls.

RESULTS

Plasma IGF-I and IGFBP-3 plasma concentrations after acute cerebral ischemia were strikingly lower than those in control subjects and healthy individuals reported in the literature. Plasma IGF-I levels in patients with large infarcts were significantly statistically lower than those in control subjects (P < .05), and plasma IGFBP-3 levels were significantly lower than those in control subjects on days 5 and 10.

CONCLUSIONS

IGF-I and IGFBP-3 plasma levels are decreased in patients after cerebral ischemia. After acute ischemic stroke, increased demand for growth factors, altered tissue distribution, and accelerated metabolic clearance rate or central inhibition of the somatotrophic axis may contribute to these low plasma concentrations. Growth factors such as IGF-I and IGFBP-3 may play an important role in the pathophysiology of acute cerebral ischemia, and growth factors may have a considerable effect on future therapeutic regimens.

Hypercalcemia in an AIDS patient treated with growth hormone

METHOD

Recombinant human growth hormone (rhGH) is a newly approved treatment for weight loss and wasting in patients with AIDS. We report a male patient with advanced AIDS who developed hypercalcemia 2 weeks after institution of rhGH therapy.

RESULTS

Parathyroid hormone, parathyroid hormone-related peptide and 1,25-dihydroxyvitamin D levels were suppressed, suggesting that hypercalcemia was mediated through alternative mechanisms. The hypercalcemia responded to discontinuation of rhGH and a single dose of intravenous pamidronate disodium and has not recurred in 8 months of follow-up.

CONCLUSION

We believe this to be the first reported case of rhGH-induced hypercalcemia in an HIV-infected patient.

Human growth hormone induces system B transport in short bowel syndrome

BACKGROUND

After massive enterectomy, remnant intestine undergoes compensatory adaptation. A combination of human growth hormone (hGH) and a glutamine-enriched modified diet induces further adaptation in patients with short bowel syndrome (SBS) on long-term total parenteral nutrition. The specific actions of each component, however, are not well-defined.

METHODS

New Zealand White rabbits were randomized to control, sham operation, or SBS (70% midjejunoileal resection) groups and treated with either hGH or saline. Sodium-dependent uptake of glucose, glutamine, alanine, leucine, and arginine into brush border membrane vesicles was quantitated. Serum insulin-like growth factor-I (IGF-I) levels were determined by immunoradiometric assay. Mucosal mRNA expression of IGF-I and IGF binding protein 4 (IGFBP-4) was evaluated by northern blot analysis using rat cDNA probes.

RESULTS

Glutamine and leucine transports were 33 and 39% greater, respectively, in the hGH-treated versus saline-treated SBS group (P < 0.05), supporting induction of system B amino acid transport. This upregulation was due, in part, to an 88% increase in glutamine carrier capacity (Vmax) with no change in carrier affinity (Km). Both hGH treatment and SBS increased serum IGF-I levels without direct correlation with increased nutrient transport. IGFBP-4 mRNA expression in small bowel mucosa of saline-treated SBS animals was significantly greater than saline-treated unoperated control values. Mucosal IGFBP-4 mRNA was not significantly altered from control in the other study groups. IGF-I mRNA expression was not detected in mucosa, but weak hybridization was noted in rabbit liver.

CONCLUSIONS

Human growth hormone accelerates early adaptation in SBS by upregulation of system B carrier capacity. Serum IGF-I levels and mucosal IGF-I and IGFBP-4 mRNA expression did not directly correlate with this enhanced nutrient transport, suggesting that hGH might exert its adaptive effects by mechanisms that are independent from the IGF system in this model.

Beneficial effects of growth hormone combined with parenteral nutrition in the management of inflammatory bowel disease: an experimental study

BACKGROUND

Growth hormone (GH) improves net protein anabolism and stimulates wound healing. Although GH is also known to exert the trophic effect on the intestinal tract, its role in the healing of intestinal ulceration is not known. The aim of this study was to evaluate the effects of exogenous GH coinfused with parenteral nutrition (PN) in an experimental model of inflammatory bowel disease in rats.

METHODS

All rats underwent central venous cannulation and were randomized to two groups after induction of small intestinal ulceration with indomethacin. Both groups received the same PN formula. In addition, the GH group (n = 10) received subcutaneous injections of human GH at a dose of 1.0 IU/kg daily for 4 days, whereas the control group (n = 10) received injections of normal saline solution. Nitrogen balance, macroscopic inflammation score, intestinal myeloperoxidase activity, DNA content, and mucosal permeability were determined for each rat. Insulin-like growth factor-I (IGF-I) mRNA was detected by reverse transcription and polymerase chain reaction.

RESULTS

Administration of GH significantly improved the cumulative nitrogen balance, ameliorated the gross inflammation score, and decreased intestinal myeloperoxidase activity. Similarly, intestinal permeability was significantly decreased in the GH group as compared with the control group. GH treatment resulted in increased plasma concentration of IGF-I and IGF-I mRNA expressions in both the liver and the small intestine compared with those in the control group.

CONCLUSIONS

Exogenous GH plays an important role in accelerating intestinal healing in an experimental model of small bowel ulceration in rats. The mechanisms may include the stimulated IGF-I production, which thereafter augments intestinal epithelial cell growth.

Low-dose recombinant human growth hormone increases body weight and lean body mass in patients with short bowel syndrome

OBJECTIVE

The authors investigate the effects of low dose recombinant human growth hormone (rhGH) on body composition and absorptive capacity in patients with short bowel syndrome from Crohn's disease.

SUMMARY BACKGROUND DATA

Patients with short bowel syndrome usually are malnourished because of malabsorption. The anabolic effects of high doses of rhGH have been tested in different clinical catabolic conditions, recently including patients with short bowel syndrome. The authors have investigated the effects of low-dose rhGH in short bowel syndrome in a placebo-controlled crossover clinical trial.

METHODS

Ten patients were treated with daily subcutaneous doses of rhGH/placebo (0.5 international units/kg-1 per week-1 = 0.024 mg/kg-1 per day-1) for 8 weeks in a randomized, double-blind, placebo-controlled crossover clinical trial with a minimum of 12 weeks wash-out. Absorptive capacity and biochemical parameters were investigated in a metabolic ward before treatment and during first and last week of treatment. Body composition was determined by DEXA-Scan (Lunar DPX, Scanexport Medical, Helsingborg, Sweden), impedance analysis, and whole body potassium counting.

RESULTS

Low-dose rhGH doubled serum levels of insulin-like growth factor-1 (IGF-1) and increased body weight, lean body mass, and total body potassium by 5% (p < 0.05). Fat-free mass and total body water increased by 6% (p = 0.008). Increases in IGF-1 levels correlated with increases in fat-free mass (r = 0.77, p < 0.02). No significant changes in absorptive capacity of water, energy, or protein were detected.

CONCLUSION

Eight weeks of low-dose rhGH treatment leads to increases in body weight, lean body mass, and fat-free mass in patients with short bowel syndrome, correlated to increases in IGF-1 levels.

Growth hormone insensitivity in children with biliary atresia

Malnutrition is a critical predictor of mortality and morbidity in children with biliary atresia who undergo orthotopic liver transplantation. Growth hormone (GH) enhances nitrogen retention in patients with chronic obstructive lung disease, sepsis, and in fasted adult volunteers. The goal of this study was to assess the acute response to recombinant human GH (rhGH) treatment in children with biliary atresia to determine whether GH therapy was likely to improve pretransplant nutritional status. Five children, aged 10-32 months, with biliary atresia and persistent cholestasis despite surgical attempts to reestablish bile flow, were studied. All five children had portal hypertension, conjugated hyperbilirubinemia, and decreased serum albumin concentrations. Length, weight, and growth velocity were decreased in all five children. Despite adequate energy and protein intake, fat stores were depleted in all five subjects, and somatic protein stores were diminished in all except one child. Baseline serum concentrations of insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) were low (8.4 +/- 2 ng/ml and 0.2 +/- 0.1 mg/l respectively). In the four children who completed the study, serum IGF-I and IGFBP-3 levels did not change after treatment with rhGH (0.1 mg/kg/day) for 4 days. Our findings indicate that children with biliary atresia awaiting liver transplantation are insensitive to GH and that treatment with GH is unlikely to promote anabolism. A rationale exists for examining the effect of treatment with IGF-I, which mediates the anabolic effects of GH.

Use of growth hormone for postoperative respiratory failure

BACKGROUND

The authors examined the efficacy of human growth hormone (HGH) in patients dependent on mechanical ventilation who were being weaned from the respirator.

METHODS

A total of 53 patients were chosen by the primary surgical team in consultation with the critical care service to undergo HGH therapy. These patients had been receiving standard ICU support and had failed standard ventilator weaning protocols. As such, they were treated with HGH in an attempt to increase respiratory muscle strength and facilitate weaning from mechanical ventilation.

RESULTS

General demographic information was recorded. Patients suffered from a high incidence of co-morbid conditions and infectious complications. The average duration of HGH therapy was 38 days, and 81% of the previously unweanable patients were eventually weaned from mechanical ventilation with an overall survival of 76%. Mortality as predicted by APACHE II Scores was significantly less than actual mortality (24% actual mortality vs. 42% predicted mortality, P < 0.05).

CONCLUSIONS

This phase I study presents clinical evidence supporting the safety and efficacy of HGH in promoting respiratory independence in a selected group of surgical ICU patients. Randomized, blinded, controlled trials now seem warranted.

Comparative effects of growth hormone on water and ion transport in rat jejunum, ileum, and colon

Specific growth hormone (GH) receptors are located along the entire rat intestine. We have recently shown that GH induces water and ion absorption in the rat ileum. This raises the possibility that GH regulates water and ion transport throughout the intestine. To test this, we have evaluated the effects of GH administration on jejunal, ileal, and colonic water and ion transport, by the in vivo rat perfused intestine, and in vitro, in corresponding segments of intestine mounted in Ussing chambers. In vivo, GH increased water absorption by 250%, 180%, and 80% over baseline in the jejunum, ileum, and colon, respectively. The effect had similar kinetics in the three intestinal regions. In vitro, serosal GH administration induced a decrease in short-circuit current, consistent with an absorptive effect. The effect showed a proximal to distal decreasing pattern. These findings suggest that GH plays a role in the body fluid homeostatic control, promoting water and ion absorption.

Lack of effects of recombinant growth hormone on muscle function in patients requiring prolonged mechanical ventilation: a prospective, randomized, controlled study

OBJECTIVE

To evaluate the benefit of recombinant human growth hormone administration on muscle strength and duration of weaning in critically ill patients undergoing prolonged mechanical ventilation.

DESIGN

Prospective, randomized, controlled, single-blind study.

SETTING

Intensive care unit.

PATIENTS

Twenty patients requiring > or = 7 days of mechanical ventilation for acute respiratory failure.

INTERVENTION

Random assignment to receive either 0.43 IU (approximately 0.14 mg) recombinant growth hormone/kg body weight/day (treated group), or saline (nontreated group) for 12 days.

MEASUREMENTS AND MAIN RESULTS

Nutritional support was guided by indirect calorimetry. Cumulative nitrogen balance was positive throughout the study period in the treated group 17.3 (44.9 +/- 17.3[SEM] g/12 days) vs. the nontreated group (-65.8 +/- 11.8 g/12 days) (p<.0001). Despite similar initial plasma concentrations, recombinant growth hormone supplementation resulted in marked increases in growth hormone, insulin like growth factor-1, and insulin concentrations (p<.05, .02, and .0001, respectively, vs. nontreated group). Body impedance determined net fat-free mass increased in the treated group (0.8 +/- 0.6 kg) vs. the nontreated group (-1.1 +/- O.5 kg) (p<.03). Initial peripheral muscle function, assessed by computer-controlled electrical stimulation of the adductor pollicis, was similarly lower in treated and nontreated groups than sex and age-matched normal controls, and decreased further during the study period. Arterial blood gases, cumulative total mechanical ventilation time, and number of hrs/day of mechanical ventilation during weaning were similar in both patient groups. Only three of the ten patients in each group were weaned from mechanical ventilation by day 12.

CONCLUSIONS

Daily administration of recombinant growth hormone in mechanically ventilated patients with acute respiratory failure promotes a marked nitrogen retention. However, this reaction is accompanied neither by an improvement in muscle strength nor by a shorter duration of ventilatory supports.

Insulin-like growth factor-I enhances immune response in dexamethasone-treated or surgically stressed rats maintained with total parenteral nutrition

BACKGROUND

New evidence suggests that insulin-like growth factor-I (IGF-I) is an important regulator of immune response. Our objective was to determine the effects of IGF-I on immune response during total parenteral nutrition (TPN) using two stress models.

METHODS

Male, Sprague-Dawley rats (230 to 250 g) were given TPN with or without coinfusion of recombinant human IGF-I (800 micrograms/d for 6 days) and subjected to either dexamethasone, a synthetic glucocorticoid, or surgical stress, in the form of a midline abdominal incision. In the dexamethasone model, immune response was assessed by total cellularity of the thymus and spleen, in vitro assays of lymphocyte proliferation, and interleukin 6 (IL-6) production, and concentrations of IL-6 and tumor necrosis factor alpha (TNF-alpha) in serum. In the surgical model, flow cytometry was used to identify and quantify splenic populations of T and B lymphocytes and macrophages.

RESULTS

In rats immunosuppressed by dexamethasone, IGF-I infusion increased mitogen-induced proliferation of thymocytes, but did not alter cellularity in the thymus; enhanced proliferation and IL-6 production in peripheral blood mononuclear cells following treatment with concanavalin A or lipopolysaccharide; and reduced the serum concentration of IL-6, but not TNF-alpha. In surgically stressed rats, IGF-I infusion restored the splenic populations of immature and mature B lymphocytes, which were decreased by TPN.

CONCLUSIONS

our data demonstrate that IGF-1 enhances immune response during TPN in rats.

The effect of recombinant human IGF-I on protein metabolism in post-operative patients without nutrition compared to effects in experimental animals

This study has evaluated the effects of recombinant human insulin-like growth factor I (rhIGF-I) to moderately stressed post-operative patients provided with dextrose as the only exogeneous substrate. Thirty patients who underwent elective colorectal surgery were randomized to receive either rhIGF-I (80 micrograms kg-1 bw) subcutaneously twice daily or placebo injections in a double-blind parallel group design. Nitrogen balance, urinary 3-methyl-histidine excretion plasma growth hormone (GH), serum cortisol, IGF-I binding proteins (IGFBP-1,3), glomerular filtration rate, plasma amino acid concentrations and whole-body energy expenditures were measured as effector variables during days 1-5 post-operatively. Animal and isolated tissue experiments were performed as additional control experiments to confirm cellular effectiveness of the recombinant material. rhIGF-I increased significantly the glomerular filtration rate and prevented the adaptive decrease in whole-body energy expenditure in response to partial starvation in the postoperative period. Serum and plasma concentrations of IGFBP-1,3 cortisol, blood glucose and amino acids were not significantly influenced by rhIGF-I administration, while plasma GH levels decreased significantly as expected. rhIGF-I had no effect on either nitrogen balance or protein breakdown (3-methylhistidine excretion) in post-operative patients on dextrose supplementation only, although plasma concentrations of IGF-I increased from 130-140 ng mL-1 to a range of 300-450 ng mL-1. In contrast, IGF-I stimulated the synthesis of both globular and myofibrillar proteins (+50%, P < 0.01), when given as a single dose (100 micrograms kg-1) 2 h before measurements of protein synthesis in skeletal muscles of overnight fasted adult mice. This stimulatory effect by IGF-I (1 microgram mL-1) was also confirmed by measurements of skeletal muscle protein synthesis in vitro (+40%, P < 0.05). Orally re-fed mice had a normal transcription of IGF-I mRNA in skeletal muscle cells, while overnight fasted mice showed a trend to down-regulated transcription. Our results demonstrate that rhIGF-I has several significant physiological effects, without major side-effects, when supplied to partially starved patients in the post-operative phase. The lack of a whole-body nitrogen sparing effect by rhIGF-I alone to post-operative patients is not clear, but was most likely explained by subnormal plasma concentrations of amino acids.

Simultaneous treatment with IGF-I and GH additively increases anabolism in parenterally fed rats

We compared the effects of recombinant human insulin-like growth factor I [rhIGF-I, 800 micrograms/day, coinfused with total parenteral nutrition (TPN)], growth hormone (rhGH, 800 micrograms/day, subcutaneous injection twice daily), and simultaneous treatment with rhIGF-I and rhGH (800 + 800 micrograms/day) in rats subjected to surgical stress and maintained with TPN. Weight gain induced by IGF-I plus GH was double that shown by IGF-I or GH alone. Although weight gain was similar with IGF-I or GH, IGF-I selectively increased heart, kidney, thymus, spleen, and small intestine mass, whereas GH selectively increased gastrocnemius muscle mass. IGF-I and/or GH increased carcass protein and water while decreasing fat. Serum total and free IGF-I levels were highest with IGF-I plus GH. Serum rat GH levels were reduced with IGF-I and/or GH. IGF-I given with GH reversed the GH-induced increase in serum insulin. In summary, IGF-I and GH show tissue-specific anabolic effects, and simultaneous treatment with IGF-I plus GH additively increases anabolism during TPN.

Growth hormone, glutamine, and a modified diet enhance nutrient absorption in patients with severe short bowel syndrome

BACKGROUND

Massive loss of intestinal surface area results in the short bowel syndrome characterized by malabsorption of fluid, electrolytes, and other nutrients. Although the remaining bowel undergoes morphological and functional adaptation, often these changes are inadequate to support the individual by enteral feedings, and parenteral nutrition is required to prevent dehydration, electrolyte disturbances, and malnutrition. Substances such as growth hormone, glutamine, and fiber exert bowel-specific trophic effects and either directly or indirectly influence nutrient absorption. This study was undertaken to determine whether the co-administration of exogenous growth hormone, supplemental glutamine, and a modified fiber-containing diet could enhance nutrient absorption in patients who had undergone massive intestinal resection.

METHODS

Ten patients (5 men, 5 women, aged 43 +/- 4 years) with short bowel syndrome were studied 6 +/- 1 years after surgical resection. All patients were admitted to the Clinical Research Center for a 28-day period; the first week served as a control period when nutritional (enteral and parenteral) and medical management simulated usual home therapy. Thereafter, eight patients received exogenous growth hormone, supplemental glutamine, and a modified high-carbohydrate, high-fiber diet. Two patients were treated with the modified diet alone. The efficiency of net nutrient absorption (percent absorbed) for total calories, protein, fat, carbohydrate, water, and sodium was calculated from the measured nutrient intake and stool losses.

RESULTS

Three weeks of treatment with growth hormone, glutamine, and a modified diet increased total caloric absorption from 60.1 +/- 6.0% to 74.3 +/- 5.0% (p < or = .003), protein absorption from 48.8 +/- 4.8% to 63.0 +/- 5.4% (p < or = .006), and carbohydrate absorption from 60.0 +/- 9.8% to 81.5 +/- 5.3% (p < or = .02). Fat absorption did not change (61.0 +/- 5.3% to 60.3 +/- 7.9%, p = NS). Water and sodium absorption increased from 45.7 +/- 6.7% to 65.0 +/- 7.3% (p < or = .002) and from 49.0 +/- 9.8% to 69.6 +/- 6.5% (p < or = .04), respectively. These absorptive changes resulted in a decrease in stool output (1,783 +/- 414 g/d control period vs 1,308 +/- 404 g/d third week of treatment, p < or = .05). Treatment with diet alone did not influence nutrient absorption or stool output.

CONCLUSIONS

The combined administration of growth hormone, glutamine, and a modified diet enhanced nutrient absorption from the remnant bowel after massive intestinal resection. These changes occurred in a group of patients that had previously failed to adapt to the provision of enteral nutrients. This therapy may offer an alternative to long-term dependence on total parenteral nutrition for patients with severe short bowel syndrome.

Characterization of growth hormone enhanced donor site healing in patients with large cutaneous burns

BACKGROUND

Human growth hormone is an anabolic agent that attenuates injury-induced catabolism and stimulates protein synthesis. Recombinant human growth hormone (rhGH) administered therapeutically to patients with massive burns has been shown to increase the rate of skin graft donor site healing. It has been postulated that growth hormone affects wound healing and tissue repair by stimulating the production of insulin-like growth factor-1 (IGF-1) by the liver to increase circulating IGF-1 concentrations. The mechanism by which it improves wound healing, however, remains in question. The authors hypothesize that rhGH up-regulates IGF-1 receptors and IGF-1 levels both systemically and locally in the wound site to stimulate cell mitosis and increase synthesis of laminin, collagen types IV and VII, and cytokeratin. This hypothesis was tested in nine patients with burns covering > 40% of total body surface area.

OBJECTIVE

The authors assessed the efficacy of rhGH in promoting several major building materials in the donor site of patients with massive burns.

METHODS

Ten massively burned patients with full-thickness burns covering more than 40% of total body surface area were participants in a placebo-controlled prospective study to determine the efficacy of 0.2 mg/kg/day rhGH on donor site wound healing and to identify some of the major components involved in wound healing and its integrity.

RESULTS

Donor sites in burn patients receiving rhGH showed an increased coverage by the basal lamina of 26% for placebo to 68% coverage of the dermal-epidermal junction. Insulin-like growth factor-1 receptors and laminin, types IV and VII collagen, and cytokeratin-14 all increased significantly. Healing times of the donor sites were significantly decreased compared with patients receiving placebo.

CONCLUSION

Results indicate that growth hormone or its secondary mediators may directly stimulate the cells of the epidermis and dermis during wound healing to produce the structural proteins and other components needed to rebuild the junctional structures.

High-calorie total parenteral nutrition reduces hepatic insulin-like growth factor-I mRNA and alters serum levels of insulin-like growth factor-binding protein-1, -3, -5, and -6 in the rat

High-calorie total parenteral nutrition (TPN) is associated with hepatic dysfunction and steatosis. Because TPN-induced steatosis might compromise hepatic expression of insulin-like growth factor-I (IGF-I) and thereby limit its potential nutritional benefit, we examined hormonal and IGF-I responses in male Sprague-Dawley rats (270 to 300 g) fed by continuous intravenous infusion with high-calorie, high-dextrose (350 kcal/kg) TPN solutions for O (control), 2, 4, and 8 days. Since IGF-binding proteins (IGFBPs) are thought to modulate the biological effects of IGFs in target tissues, we also determined serum levels of IGFBPs. Animals developed hepatic steatosis after 2 to 8 days of TPN, as reflected by a sevenfold to 15-fold increase in hepatic triacylglycerol content (P < .001 v control on each day). Serum corticosterone and insulin levels were significantly higher after 2 and 4 days of TPN, whereas serum growth hormone levels were reduced after 4 and 8 days. Serum IGF-I levels were not significantly different during TPN. However, there was a coordinate reduction in the three major hepatic IGF-I transcripts (7.0, 1.9, and 1.0 kb) after 2, 4, or 8 days of TPN, and IGF-I transcripts corresponding to multiple initiation sites within exons 1 and 2 were coordinately downregulated with TPN. Western ligand blotting indicated that serum levels of 38K to 43K, 30K to 34K, and 24K IGFBPs were increased approximately twofold after 4 and 8 days of TPN as compared with control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent advances: parenteral nutrition support

Even though there is an abundance of research related to the clinical and physiologic effects of parenteral nutrition and specific nutritional substrates, few new products have been released for clinical use. This review illustrates some of the directions being taken in the future development of parenteral nutrition products and some new perspectives related to the current effects (or lack of effects) of TPN. When considering the individual effects of specific nutrient substrates (arginine, glutamine, LCTs, MCTs, SCFAs) as reviewed here, it becomes apparent that the infusion of parenteral nutrition has the potential to produce a variety of metabolic responses that could be both beneficial and harmful. These effects depend on the type and quantity of substance infused as well as the disease and clinical condition of the patient. This also is true for those substances (GH, IGF-1) being evaluated to direct the effects of TPN infusions in a manner that improves protein accretion and supports the immunologic response of the body. At best, these investigations are producing a great amount of new and more specific information about the metabolic response to illness and the effects of TPN and individual substrate on that response.

Use of total parenteral nutrition in children with cancer: a review and some recommendations

Total parenteral nutrition (TPN) is now a standard component of supportive treatment in many pediatric oncology units for patients undergoing intensive therapy. TPN incurs many risks and significant costs, however, that may not always be balanced by major benefits. Infection rates are reported to be high in patients receiving TPN, and TPN use is associated with a range of metabolic problems. With standard TPN regimens, the catabolic state of many intensively treated patients may not be adequately reversed. Because TPN may enhance tumor cell growth, there is justifiable concern about giving TPN when a cancer patient is not also receiving cytotoxic therapy. Recommendations for TPN use in pediatric oncology patients include using TPN formulas containing glutamine to stimulate anabolism and timing TPN cycles to be given just before cytotoxic chemotherapy, when stimulation of tumor growth might actually improve the effectiveness of antimitotic chemotherapy.

Growth hormone enhances amino acid uptake by the human small intestine

OBJECTIVE

The effects of growth hormone (GH) on the luminal transport of amino acids and glucose by the human small intestine were investigated.

SUMMARY BACKGROUND DATA

The anabolic effect of growth hormone administration is associated with nitrogen retention and an increase muscle strength, but the impact of growth hormone on nutrient uptake from the gut lumen has not been examined.

METHODS

Twelve healthy patients received a daily subcutaneous dose of low-dose GH (0.1 mg/kg), high-dose GH (0.2 mg/kg), or no treatment (controls) for 3 days before surgery. At operation, ileum (8 patients) or jejunum (4 patients) was resected, and brush border membrane vesicles (BBMVs) were prepared by differential centrifugation. Vesicle purity was confirmed by a 16-fold enrichment of marker enzymes. The carrier-mediated transport of glutamine (System B), leucine (System L), alanine (System B), arginine (System y+), MeAIB (methyl alpha-aminoisobutyric acid [System A]), and glucose (Na(+)-dependent glucose transporter) by BBMVs was measured by a rapid mixing/filtration technique.

RESULTS

Treatment with low-dose GH resulted in a statistically insignificant increase in amino acid transport rates in jejunal and ileal BBMVs. High-dose GH resulted in a generalized 20%-to 70%-stimulation of amino acid transport, whereas glucose transport was not affected. The effects of GH were similar in ileum and jejunum. Kinetic analysis of the transport of glutamine (the most abundant amino acid in the body and the principal gut fuel) and the essential amino acid leucine revealed that the increase in transport was caused by a 50% increase in carrier Vmax, consistent with an increase in the number of functional carriers in the brush border membrane. Pooled analysis of transport velocities demonstrated that total rates of amino acid uptake from the gut lumen were increased significantly by 35% in GH-treated patients.

CONCLUSIONS

The ability of GH to enhance amino acid uptake from the gut lumen provides energy and precursors for protein synthesis in the gut mucosa, as well as additional substrate for anabolism in other organs.

Anabolic effect of IGF-I coinfused with total parenteral nutrition in dexamethasone-treated rats

We determined the anabolic effects of recombinant human insulin-like growth factor I (rhIGF-I, 800 micrograms/day) coinfused with total parenteral nutrition (TPN) in male Sprague-Dawley rats (230-250 g), with and without dexamethasone (Dex, 70 micrograms/day)-induced catabolism for 6 days. Dex without IGF-I increased serum insulin concentrations 300% and glucose concentrations 20%; IGF-I plus Dex significantly reduced serum insulin and glucose concentrations to TPN control levels. Animals given Dex without IGF-I lost 30 +/- 3 g; IGF-I plus Dex reduced the weight loss to 9 +/- 3 g, P < 0.001. IGF-I without Dex resulted in a weight gain of 14 +/- 2 g compared with a gain of 4 +/- 1 g in TPN controls, P < 0.01. Determination of nitrogen balance and body composition confirmed that changes in body weight were due to corresponding changes in nitrogen excretion and total body protein content. IGF-I significantly reduced TPN-induced intestinal atrophy, resulting in a 30% increase in weight of the small intestine plus colon compared with TPN without IGF-I. These results indicate that coinfusion of rhIGF-I with TPN counteracts Dex-induced insulin resistance and has a significant net anabolic effect when given with or without Dex in rats.

Nutritional assessment and the role of preoperative parenteral nutrition in the colon cancer patient

Hospital-based malnutrition is prevalent, especially among patients with gastrointestinal malignancy. Colorectal cancers produce malnutrition through impairment of gastrointestinal function and the liberation of cytokines. Malnourished patients who undergo operation have an increased likelihood of perioperative morbidity and mortality. The performance of a nutritional assessment will aid in the recognition of such patients and provide a risk assessment profile. Preoperative parenteral nutrition is a major expense and delays surgical intervention. Studies to document the efficacy of preoperative parenteral nutrition suffer from design flaws and small sample sizes. Studies that exclusively address patients with cancer of the colon and rectum are absent; therefore results must be extrapolated from the existing literature. Cumulative evidence suggests that a 7-10 day period of parenteral nutrition repletion in the severely malnourished patient will diminish the incidence of postoperative septic complications and mortality. The preoperative treatment of lesser degrees of malnutrition remain controversial. Once the decision has been made to institute preoperative parenteral alimentation, attention to the details of protein requirements and caloric needs should be stressed. The endpoint of therapy is poorly defined. The role of glutamine, arginine, omega-3 fatty acids, and growth hormone in the preoperative repletion process provide an exciting arena for future research.

Strategies for attenuating protein-catabolic responses in the critically ill

Specialized enteral and parenteral nutrition are now a standard components of care in critically ill patients. This adjunctive therapy corrects and prevents nutrient deficiencies, attenuates the loss of body protein, and improves clinical outcomes in malnourished patients. Several novel strategies designed to improve the metabolic and clinical effects of specialized nutrition are under vigorous clinical investigation. These new approaches include increased emphasis on enteral feeding to maintain intestinal absorptive, immune, and barrier function; administration of conditionally essential amino acids (glutamine, arginine); use of specialized lipid products and antioxidants; and administration of growth factors such as human growth hormone. Randomized, controlled clinical trials will define the clinical and metabolic efficacy and cost-effectiveness of these therapies in specialized nutrition support.