Acute IGF-1 deficiency in multiple trauma victims

Allostatic Load as a Complex Clinical Construct: A Case-Based Computational Modeling Approach

Allostatic load (AL) is a complex clinical construct, providing a unique window into the cumulative impact of stress. However, due to its inherent complexity, AL presents two major measurement challenges to conventional statistical modeling (the field's dominant methodology): it is comprised of a complex causal network of bioallostatic systems, represented by an even larger set of dynamic biomarkers; and, it is situated within a web of antecedent socioecological systems, linking AL to differences in health outcomes and disparities. To address these challenges, we employed case-based computational modeling (CBM), which allowed us to make four advances: (1) we developed a multisystem, 7-factor (20 biomarker) model of AL's network of allostatic systems; (2) used it to create a catalog of nine different clinical AL profiles (causal pathways); (3) linked each clinical profile to a typology of 23 health outcomes; and (4) explored our results (post hoc) as a function of gender, a key socioecological factor. In terms of highlights, (a) the Healthy clinical profile had few health risks; (b) the pro-inflammatory profile linked to high blood pressure and diabetes; (c) Low Stress Hormones linked to heart disease, TIA/Stroke, diabetes, and circulation problems; and (d) high stress hormones linked to heart disease and high blood pressure. Post hoc analyses also found that males were overrepresented on the High Blood Pressure (61.2%), Metabolic Syndrome (63.2%), High Stress Hormones (66.4%), and High Blood Sugar (57.1%); while females were overrepresented on the Healthy (81.9%), Low Stress Hormones (66.3%), and Low Stress Antagonists (stress buffers) (95.4%) profiles.

Elevated Serum Insulin-Like Growth Factor 1 Levels in Patients with Neurological Remission after Traumatic Spinal Cord Injury

After traumatic spinal cord injury, an acute phase triggered by trauma is followed by a subacute phase involving inflammatory processes. We previously demonstrated that peripheral serum cytokine expression changes depend on neurological outcome after spinal cord injury. In a subsequent intermediate phase, repair and remodeling takes place under the mediation of growth factors such as Insulin-like Growth Factor 1 (IGF-1). IGF-1 is a promising growth factor which is thought to act as a neuroprotective agent. Since previous findings were taken from animal studies, our aim was to investigate this hypothesis in humans based on peripheral blood serum. Forty-five patients after traumatic spinal cord injury were investigated over a period of three months after trauma. Blood samples were taken according to a fixed schema and IGF-1 levels were determined. Clinical data including AIS scores at admission to the hospital and at discharge were collected and compared with IGF-1 levels. In our study, we could observe distinct patterns in the expression of IGF-1 in peripheral blood serum after traumatic spinal cord injury regardless of the degree of plegia. All patients showed a marked increase of levels seven days after injury. IGF-1 serum levels were significantly different from initial measurements at four and nine hours and seven and 14 days after injury, as well as one, two and three months after injury. We did not detect a significant correlation between fracture and the IGF-1 serum level nor between the quantity of operations performed after trauma and the IGF-1 serum level. Patients with clinically documented neurological remission showed consistently higher IGF-1 levels than patients without neurological remission. This data could be the base for the establishment of animal models for further and much needed research in the field of spinal cord injury.

Effect of recombinant human growth hormone and insulin-like growth factor-1 administration on IGF-1 and IGF-binding protein-3 levels in brain injury

STUDY OBJECTIVE

To assess the effect of recombinant human growth hormone (rhGH) on the insulin-like growth factor-1 (IGF-1) plasma concentration versus time profile during continuous infusion of recombinant human (rh)IGF-1 to patients with traumatic brain injury (TBI).

SETTING

University of Kentucky Chandler Medical Center.

PATIENTS

Twenty-three patients with TBI (aged 18-59 yrs) with Glascow Coma Scale scores of 4-10.

INTERVENTION

Patients were randomized to receive rhIGF-1 0.01 mg/kg/hour and daily subcutaneous doses of rhGH 0.05 mg/kg/day or saline for 14 days.

MEASUREMENTS AND MAIN RESULTS

Plasma concentrations of IGF-1 and IGF-binding protein (BP)-3 were quantified by radioimmunoassay. Patients receiving rhIGF-1/rhGH reached a peak IGF-1 concentration (1199.3+/-84.0 microg/L) at 72 hours and maintained it throughout the study. Levels of IGF-1 in the control group did not change significantly above baseline throughout the study. Concentrations of IGFBP-3 were significantly higher after 48 hours in the treated group (5.1+/-0.4 mg/L) than in controls (2.9+/-0.5 mg/L) and continued until the end of the study (p<0.05).

CONCLUSION

Infusion of rhIGF-1 in conjunction with rhGH effectively achieved and maintained supraphysiologic IGF-1 plasma concentrations throughout the dosing period in patients with TBI. It appears that rhGH alters the IGF-1 plasma concentration versus time profile during continuous administration. Although speculative, changes in protein binding of IGF-1 are the most likely mechanism.

Gender differences in the responses of serum insulin-like growth factor-1 and transthyretin (prealbumin) to trauma

OBJECTIVE

To determine whether factors such as age, gender, and severity of injury should be considered when evaluating serum insulin-like growth factor (IGF)-1 and transthyretin concentrations as markers of nutritional status after trauma. A large, diverse group of patients was studied before the confounding effects of acute nutrient deprivation.

DESIGN

Prospective, randomized, descriptive study.

SETTING

Emergency room of a university hospital.

PATIENTS

One hundred eight trauma patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In this heterogeneous group of patients, Injury Severity Score ranged from 1 to 45 (11.5 +/- 10.3 [SD]), age ranged from 18 to 77 yrs (35 +/- 15.3 [SD]), and 68% were male and 32% were female. A venous blood sample was collected on admission and analyzed for serum IGF-1, transthyretin, albumin, and C-reactive protein concentrations. Relationships among variables were tested with multiple regression, Pearson's correlation coefficients, and analysis of variance. Gender, age, and severity of injury demonstrated strong and interactive effects on serum IGF-1 concentrations. IGF-1 concentrations were predicted with the following equations in women and men, respectively: y = 414 - 10.87(age) + 1.19(Injury Severity Score) + .09(age2); y = 454 - 10.87(age) - 2.57(Injury Severity Score) + .09(age2); (R2 = .35, p < .0001). The relationship between age and IGF-1 was curvilinear in both men and women. IGF-1 concentrations increased with age until approximately 57 yrs, and then decreased with increasing age. In women, IGF-1 concentrations increased with increasing severity of injury. In men, IGF-1 concentrations decreased with increasing Injury Severity Scores. This dissimilar response to injury between men and women was also seen in the significant interaction between gender and Injury Severity Score in predicting transthyretin concentrations (R2 = .32, p < .05). In men, transthyretin concentrations decreased significantly with severe injury; in women, transthyretin concentrations remained stable with severe injury. Albumin concentrations were predicted by injury severity and serum osmolality, but not gender. C-reactive protein, and time postinjury did not significantly influence the serum proteins (serum IGF-1, transthyretin, or albumin). Without consideration of age or severity of injury, mean concentrations of IGF-1, transthyretin, albumin, and C-reactive protein were not different between men and women, and were within normal expected ranges.

CONCLUSIONS

Serum IGF-1 and transthyretin concentrations, measured without the confounding effects of acute nutrient deprivation, were influenced by the severity of the injury in patients suffering traumatic injury. Age was an important determinant of serum IGF-1 in men and women even in severe trauma. The present study indicated that men and women demonstrate different physiologic responses to trauma. Women responded to increasing severity of injury with increased serum IGF-1 and little change in transthyretin concentrations. In men, both IGF-1 and transthyretin concentrations decreased with severe injury. Interpretation of serum concentrations of IGF-1 and transthyretin as markers of nutritional status after trauma should include consideration of age, gender, and severity of injury.

Integrated nutritional, hormonal, and metabolic effects of recombinant human growth hormone (rhGH) supplementation in trauma patients

An anabolic stimulus is needed in addition to conventional nutritional support in the catabolic "flow" phase of severe trauma. One promising therapy appears to be rhGH infusion which has direct as well as hormonal mediated substrate effects. We investigated on a whole-body level, the basic metabolic effects of trauma within 48-60 h after injury in 20 severely injured (injury severity score [ISS] = 31 +/- 2), highly catabolic (N loss = 19 +/- 2 g/d), hypermetabolic (resting energy expenditure [REE] = 141 +/- 5% basal energy expenditure [BEE]), adult (age 46 +/- 5 y) multiple-trauma victims, before starting nutrition therapy and its modification after 1 wk of rhGH supplementation with TPN (1.1 x REE calories, 250 mg N.kg-1.d-1). Group H (n = 10) randomly received at 8:00 a.m. on a daily basis rhGH (0.15 mg.kg-1.d-1) and Group C (n = 10) received the vehicle of infusion. Protein metabolism (turnover, synthesis and breakdown rates, and N balance); glucose kinetics (production, oxidation, and recycling); lipid metabolism, (lipolysis and fat oxidation rates), daily metabolic and fuel substrate oxidation rate (indirect calorimetry); and plasma levels of hormones, substrates, and amino acids were quantified. In group H compared to group C: N balance is less negative (-41 +/- 18 vs -121 +/- 19 mg N.kg-1.d-1, P = 0.001); whole body protein synthesis rate is 28 +/- 2% (P = 0.05) higher; protein synthesis efficiency is higher (62 +/- 2% vs 48 +/- 3%, P = 0.010); plasma glucose level is significantly elevated (256 +/- 25 vs 202 +/- 17 mg/dL, P = 0.05) without affecting hepatic glucose output (1.51 +/- 0.20 vs 1.56 +/- 0.6 mg N.kg-1.min-1), glucose oxidation and recycling rates; significantly enhanced rate of lipolysis (P = 0.006) and free fatty acid reesterification (P = 0.05); significantly elevated plasma levels of anabolic GH, IGF-1, IGFBP-3, and insulin; trauma induced counter-regulatory hormone (cortisol, glucagon, catecholamines) levels are not altered; trauma induced hypoaminoacidemia is normalized (P < 0.05) and 3-methylhistidine excretion is significantly low (P < 0.001). Improved plasma IGF-1 levels in Group H compared with Group C account for protein anabolic effects of adjuvant rhGH and may be helpful in promoting tissue repair and early recovery. Skeletal muscle protein is spared by rhGH resulting in the stimulation of visceral protein breakdown. The hyperglycemic, hyperinsulinemia observed during rhGH supplementation may be due to defective nonoxidative glucose disposal, as well as inhibition of glucose transport activity into tissue cells. The simultaneous operation of increased lipolytic and reesterification processes may allow the adipocyte to respond rapidly to changes in peripheral metabolic fuel requirements during injury. This integral approach helps us to better understand the mechanism of the metabolic effects of rhGH.

Adjuvant recombinant human growth hormone does not augment endogenous glucose production in total parenteral nutrition-fed multiple trauma patients

Hyperglycemia and insulin resistance are well-known, consistent responses to severe injury. The purpose of this study was to investigate the mechanism for the further exaggerated hyperglycemia due to adjuvant recombinant human growth hormone (rhGH) treatment in multiple trauma patients. We have measured in 20 adult severely injured, highly catabolic, hypermetabolic multiple trauma patients, the glucose kinetics (appearance, clearance, oxidation, and recycling) once in the basal state (study I), 48 to 60 hours after injury but before starting nutritional therapy, and again (study II) after 7 days of intravenous nutrition (1.1 times resting energy expenditure, 250 mg nitrogen [N]/kg/d) with or without adjuvant rhGH. Group H (n = 10) randomly received daily (8 AM) rhGH (0.15 mg/kg/d) and group C (n = 10) received the vehicle of infusion. Adjuvant rhGH treatment in intravenously fed trauma patients (1) increases plasma insulin-like growth factor-1 (IGF-1) and insulin concentrations, (2) improves N balance, and (3) exaggerates the hyperglycemic response without affecting endogenous glucose output, glucose oxidation, or recycling. The mechanism for the hyperglycemic hyperinsulinemia in trauma may be due to a defective nonoxidative glucose disposal, as well as inhibition of glucose transport activity into tissue cells.

Plasma levels of insulin-like growth factor binding protein-3 in acute trauma patients

Insulin-like growth factors (IGFs) are a family of polypeptides that regulate cell growth. Their action and bioavailability are modified by binding proteins such as IGF binding protein-3 (IGFBP-3). Plasma IGFBP-3 level was found to be growth hormone (GH)-dependent, which makes detection of IGFBP-3 useful in the evaluation of GH secretion. In the early catabolic flow phase of severe injury, when plasma levels of GH and IGF-1 are low versus uninjured levels, the role of IGFBP-3 has not been investigated. We have measured basal levels of these polypeptide hormones in 16 adult (13 men and three women aged 47 +/- 7 years) severely injured (Injury Severity Score, 32 +/- 2), hypermetabolic resting energy expenditure [REE] to basal energy expenditure [BEE] ratio, 1.30 +/- 0.05), ventilator-dependent, multiple-trauma patients within 48 to 60 hours of injury when the patients were receiving maintenance fluids without calories or nitrogen. These basal values were compared with those of 16 age-matched postabsorptive normals. In the catabolic flow phase of injury, plasma levels of GH, IGF-1, and IGFBP-3 were significantly reduced by 50%, 46%, and 45%, respectively. There was a significant linear inverse relationship between IGFBP-3 and age and also a positive correlation between IGFBP-3 and IGF-1 in both control and injured subjects. The ratio of IGFBP-3 to IGF-1 was not changed in trauma victims. Measurement of plasma IGFBP-3 levels has potential as a marker for monitoring GH therapeutic efficacy.

Adjuvant recombinant human growth hormone stimulates insulin-like growth factor binding protein-3 secretion in critically ill trauma patients

The early catabolic phase of severe injury is associated with acute growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein-3 (IGFBP-30 deficiency. The metabolic half-life of circulating IGF-1 is prolonged by its binding to IGFBP-3. The role of this binding protein in nutritionally repleted multiple-injury patients has not been previously evaluated. We have measured plasma levels of these polypeptides and nitrogen (N) balance in 18 adult (15 males/3 females; mean age, 45 years), severely injured, hypermetabolic, and highly catabolic trauma patients within 48 to 60 hours after injury, when they were receiving maintenance fluids without calories or N and during 6 days of total parenteral nutrition (TPN). Before instituting TPN, the patients were randomized to receive (group H, n = 9) or not to receive (group C, n = 9) daily recombinant human growth hormone (rhGH), 0.15 mg/kg IM. Adjuvant rhGH significantly increases plasma levels of GH, IGF-1, IGFBP-3, and insulin. In addition, it shows better improvement in N balance. The bioavailability of IGF-1 is increased, as indicated by the decrease in IGFBP-3:IGF-1 ratio. A significant correlation between IGF-1 and IGFBP-3 levels is present in the trauma patients who received TPN and rhGH. A GH/IGF-1/IGFBP-3 axis that closely regulates the metabolic status of the patient is established in trauma.

Pulsatile nature of growth hormone levels in critically ill trauma victims

BACKGROUND

Circulating growth hormone (GH) levels in normal persons fluctuate widely because of pulsatile GH secretion. It is not known whether this pulsatile nature and rhythmicity exist in severe injury. These data become necessary to decide the timing of supplementary GH administration for its optimal utilization. The purpose of this study was to investigate the GH circadian variation with respect to that of insulin-like growth factor-1 (IGF-1), insulin, C-peptide, and cortisol in the early flow phase of injury.

METHODS

Plasma GH, IGF-1, insulin, C-peptide, and cortisol levels were measured at 1-hour intervals during 24 hours (8 AM to 8 AM) in 10 severely injured adults with multiple trauma during the early catabolic flow phase 24 to 48 hours after injury, when patients received maintenance fluids without calories or nitrogen.

RESULTS

The 24-hour integrated GH concentration is not different from either 12-hour mean diurnal or 12-hour mean nocturnal or mean 8 AM GH concentration. Pulsatile GH bursts persist in injured patients during both day and night. Pulsatile bursts do not exist for IGF-1, insulin, and C-peptide. The plasma levels of cortisol show time-dependent daily maximum and minimum levels.

CONCLUSIONS

Pulsatile GH bursts persist in injured patients but less frequently than seen in normal persons. The time of bolus administration of GH to augment the anabolic GH action in patients with trauma does not matter; however, for convenience morning administration may be preferable for patients in the intensive care unit.

Adjuvant recombinant human growth hormone normalizes plasma amino acids in parenterally fed trauma patients

BACKGROUND

The addition of an anabolic stimulant during intensive nutrition therapy in trauma patients seems to be a reasonable adjuvant for minimizing muscle-mass erosion. The plasma free amino acid pattern is the mirror of the net amino acid metabolism, and we have measured the progressive changes resulting from recombinant human growth hormone therapy in trauma victims during nutritional repletion in the early catabolic flow phase of injury.

METHODS

In 20 severely injured (injury severity scale = 31 +/- 2), highly catabolic, and hypermetabolic adult multiple-trauma patients, we have measured the fasting (day 0) plasma amino acid levels (48 to 60 hours after injury before starting the nutrition therapy) and their progressive changes during 7 days of IV nutrition support (total parenteral nutrition, 1.1 x resting energy expenditure calories, 250 mg of nitrogen per kilogram per day) with or without adjuvant recombinant human growth hormone. Group H (n = 10) randomly received daily recombinant human growth hormone (0.15 mg of Somatropin per kilogram per day) and Group C (n = 10) received the vehicle of infusion.

RESULTS

Hypoaminoacidemia of trauma is normalized by infusion of recombinant human growth hormone, which indicates its anabolic nature, and this is confirmed in the cumulative nitrogen balance (-281 +/- 139 mg of nitrogen per kilogram per 7 days compared with -809 +/- 151 mg of nitrogen per kilogram per 7 days without recombinant human growth hormone; p < or = .005). This improved nitrogen retention is also reflected in the significantly low blood urea nitrogen levels in the recombinant human growth hormone group, which represents the efficient utilization of the infused amino acids for synthesis of proteins. Elevated plasma insulin-like growth factor-1 levels in Group H compared with those in Group C may also account for this altered amino acid metabolism.

CONCLUSIONS

Recombinant human growth hormone treatment in combination with conventional total parenteral nutrition in the immediate posttraumatic period improved nitrogen metabolism and normalized the plasma free amino acid levels.

Metabolic, endocrine and haematological responses to intravenous E. coli endotoxin administration in 1-week-old calves

Responses to i.v. injected E. coli endotoxin (E), followed by saline infusion, as compared with saline infusion alone, were studied for 24 h in 1-week-old calves. After administration of E, respiratory rate (RR), heart rate (HR), rectal temperature (RT), serum iron, insulin, (I), cortisol and tumor necrosis factor-alpha, transiently, and urea, continuously, increased. Isoleucine and leucine became elevated at 24 h, whereas white-blood-cell number, free fatty acids (FFA) and triglycerides (TG) increased after an initial fall. After administration of E, packed-cell volume, erythrocyte number, haemoglobin, glucose (G), cholesterol, phospholipids (PL), lysine, arginine, proline, citrulline, calcium (Ca), inorganic phosphorus, insulin-like growth factor I (IGF-I) and 3,5,3'-triiodothyronine (T3) concentrations and alkaline phosphatase (AP) and gamma-glutamyl transferase (gamma GT) activities increased significantly while growth hormone decreased non-significantly. When saline was infused alone, G, TG, PL, Ca, AP, gamma GT, I, IGF-I and T3 decreased, while FFA, urea and sodium increased, but, changes of G, urea, AP, IGF-I and T3 were less marked than after injection of E. Potassium, total protein and albumin concentrations, and glutamyl dehydrogenase and glutamate oxalacetate transaminase activities were not significantly affected by either treatment. In conclusion, metabolic and endocrine changes during saline infusion alone were typical for food withdrawal. Changes of variables after administration of E were transient, biphasic or sustained, thus expressing complex interactions between metabolic parameters, endocrine factors and cytokines.

Critical care for the elderly patient

Elderly individuals will continue to make up a major portion of patients requiring critical care. Age and chronic disease-related factors blunt the reserves with which the elderly can meet the demands of critical surgical illness. The clinician must remain vigilant to subtle changes in the patient's course which may indicate a developing complication and must pay attention to all the details of comprehensive critical care management. With careful attention and timely physiologic support, the elderly patient has as good a chance of surviving as a similarly ill younger patient, although his or her course may be more prolonged. The priorities are the same. Thus, the primary disease must be addressed: necrotic tissue débrided, pus drained, wounds closed, fractures set. Cardiopulmonary performance (oxygen delivery) must be maintained sufficiently to meet the heightened oxygen needs associated with critical illness. This may require invasive hemodynamic monitoring and pharmacologic support. Gas exchange in the lungs must be maintained without compromising cardiovascular function or exhausting the patient. Patients should be kept warm, pain free, and calm. Intravascular volume and the composition of the extracellular fluid must be maintained. Nutritional support should be provided early in amounts sufficient to meet the patient's basal nutritional requirements and increased needs associated with the critical illness. If at all possible, some or all of this nutritional support should be provided via the gastrointestinal tract. The use of specialized nutrients or of agents designed to minimize the catabolism of critical illness or to enhance anabolism is an area of active investigation. The indications for these therapeutic strategies in the elderly should become clearer in the years ahead.