Michael Højby Rasmussen

The impact of obesity, fat distribution, and energy restriction on insulin-like growth factor-1 (IGF-1), IGF-binding protein-3, insulin, and growth hormone

The aim of this study was to characterize the association between serum insulin-like growth factor-1 (IGF-1) and obesity, as well as fat distribution, before and during moderate energy restriction (1,200 kcal/d). In 51 females and nine males having a body mass index (BMI) between 27 and 39 kg/m2, relationships between serum IGF-1, IGF-binding protein-3 (IGFBP-3), insulin, growth hormone (GH), blood glucose, and anthropometric measurements of body fat were examined. The patients were studied before treatment and again after 8 and 16 weeks of dieting. Visceral adipose tissue (AT) was estimated by anthropometric computed tomography (CT)-calibrated equations. In females, IGF-1 was inversely associated with the abdominal sagittal diameter (SagD) and with the visceral AT (r = -.41, P = .006). No significant correlations were found between IGF-1 and BMI or other indices of adiposity. Weight loss caused a temporary increase in IGF-1 concentrations (P = .03) and continued decrements in blood glucose levels (P = .0004 at 16 weeks). A statistically significant inverse correlation between IGF-1 and blood glucose levels was present before (r = -.30, P = .02) and after 8 (r = -.37, P = .007) and 16 (r = .02, P = .02) weeks of dietary treatment. Both serum IGF-1 and insulin levels were positively correlated with serum IGFBP-3 levels (r = .34, P = .009 and r = .34, P = .008, respectively). We conclude that IGF-1 levels in obese females reflect the intraabdominal fat mass rather than obesity per se. IGF-1 and blood glucose levels are inversely correlated in obesity before and during energy restriction.

Obesity, growth hormone and weight loss

Growth hormone (GH) is the most important hormonal regulator of postnatal longitudinal growth in man. In adults GH is no longer needed for longitudinal growth. Adults with growth hormone deficiency (GHD) are characterised by perturbations in body composition, lipid metabolism, cardiovascular risk profile and bone mineral density. It is well established that adult GHD usually is accompanied by an increase in fat accumulation and GH replacement in adult patients with GHD results in reduction of fat mass and abdominal fat mass in particular. It is also recognized that obesity and abdominal obesity in particular results in a secondary reduction in GH secretion and subnormal insulin-like growth factor-I (IGF-I) levels. The recovery of the GH IGF-I axis after weight loss suggest an acquired defect, however, the pathophysiologic role of GH in obesity is yet to be fully understood. In clinical studies examining the efficacy of GH in obese subjects very little or no effect are observed with respect to weight loss, whereas GH seems to reduce total and abdominal fat mass in obese subjects. The observed reductions in abdominal fat mass are modest and similar to what can be achieved by diet or exercise interventions.

Effects of growth hormone in patients with tibial fracture: a randomised, double-blind, placebo-controlled clinical trial.

OBJECTIVE Investigate whether intervention with GH after tibial fracture enhances fracture healing. DESIGN Randomised, double-blind, placebo-controlled study in 406 patients (93 women, 313 men, age: 18-64 years) with tibial fracture. METHODS Patients were stratified by tibial fracture (open or closed) and allocated to placebo or GH treatment (15, 30 or 60 mug/kg daily, until clinically assessed healing or until 16 weeks post-surgery). Primary outcome was time from surgery until fracture healing and assessment of healing was done centrally and observer blinded. Patients reported for evaluation every 4 weeks until 24 weeks, and at 9 and 12 months. RESULTS GH did not accelerate time to healing in the combined group of open and closed fractures. When separately analysing the closed and open fractures, a significant difference in time to healing was observed between treatment groups, exclusively in the closed fractures (P<0.05; subgroup analysis revealed that the 60 microg/kg group was significantly different from placebo). The relative risk of fracture healing for 60 microg/kg versus placebo during the 12 month was: all fractures, 1.16; 95% CI: (0.86; 1.57) (ns); closed fractures, 1.44; 95% CI: (1.01; 2.05; P<0.05); open fractures, 0.75; 95% CI: (0.42; 1.31) (ns). The estimated median number of days before fracture healing in closed fractures was 95 with 60 microg/kg versus 129 with placebo (95% CI: (94; 129) and (94; 249)) corresponding to approximately 26% decrease in healing time. CONCLUSIONS In the overall group of open and closed tibial fractures, no significant enhancement of fracture healing was observed with GH, whereas in closed tibial fractures, GH accelerated healing significantly.

GH administration and discontinuation in healthy elderly men: effects on body composition, GH-related serum markers, resting heart rate and resting oxygen uptake

BACKGROUND AND OBJECTIVES GH administration results in increased lean body mass (LBM), decreased fat mass (FM) and increased energy expenditure (EE). GH therapy may therefore have potential benefits, especially in the elderly, who are known to have decreased function of the GH/IGF‐I axis. Several studies have focused on effects of GH administration in the elderly in the last decade. However, very limited information is available regarding changes in body composition and EE upon GH discontinuation in the elderly. The present study therefore investigated the effects of 12 weeks of GH administration and subsequent discontinuation on body composition, resting oxygen uptake (VO2), resting heart rate (HR) and GH related serum markers in healthy elderly men.

Long-acting pegylated human GH in children with GH deficiency: a single-dose, dose-escalation trial investigating safety, tolerability, pharmacokinetics and pharmacodynamics.

OBJECTIVE GH replacement therapy currently requires daily injections, which may be inconvenient and distressing for young patients. This study determined the safety, tolerability, pharmacokinetics and pharmacodynamics of escalating single doses of a pegylated GH (NNC126-0083) developed for once-weekly administration, in children with GH deficiency (GHD). DESIGN AND METHODS Thirty children (age ≥6 and ≤12 years, weight ≥16 kg) were randomised to NNC126-0083 or daily GH treatment. The subjects discontinued their daily GH treatment 7-9 days before receiving NNC126-0083 at 0.01, 0.02, 0.04 or 0.06 mg protein/kg (n=22) or seven once-daily doses of GH at 0.035 mg protein/kg (n=8). RESULTS NNC126-0083 was well tolerated, and no short-term safety or local tolerability issues were identified. After NNC126-0083 treatment, dose-dependent IGF1 increases were evident for maximum concentration (C(max)), but not area under the curve (AUC(0)(-)(168 h)). Mean values for IGF1 AUC(0)(-)(168 h)/168 h and C(max) were higher for GH than for NNC126-0083, although the difference was not statistically significant for cohorts 0.06 mg protein/kg. At 0.06 mg protein/kg, the resulting IGF1 response began subsiding at ∼3 days post-dose. CONCLUSION Single doses of long-acting NNC126-0083 were safe and well tolerated in children with GHD. Increased IGF1 levels were observed in all NNC126-0083 dose groups; however, a satisfactory once-weekly IGF1 profile was not reached within the NNC126-0083 dose levels administered.

No effect of growth hormone administration on substrate oxidation during exercise in young, lean men

The purpose of this study was to examine the effects of increased fat availability induced by growth hormone (GH) administration on the oxidative metabolism during exercise. Seven well‐trained males (age 25 ± 2 years (mean ±s.e.m.); peak oxygen consumption : 62 ± 1 ml min−1 kg−1 (completed four randomised trials: 120 min bicycling at 55% 4 h after receiving either 7.5 IU (2.5 mg) GH or placebo (Plc), and during rest after receiving either GH or Plc. In all studies a standardized meal was given 2 h after GH or Plc injection. GH administration resulted in an ∼60‐fold increase in serum GH concentration at rest (P < 0.0001) and during exercise (P < 0.0001). The increase in serum GH was followed by an increase in circulating glycerol at rest (8%, P < 0.0001). When combined with exercise the increase in plasma glycerol was more pronounced (GH: 716% of baseline versus Plc: 328%, P < 0.0001). However, this increase in fat mobilization did not increase fat oxidation during exercise (indirect calorimetry). In conclusion, GH administration combined with aerobic exercise increased lipolytic parameters substantially more than exercise alone, but did not further augment whole body fat oxidation.

Effect of Weight Loss on Free Insulin‐Like Growth Factor‐I in Obese Women With Hyposomatotropism

Objective: It has been hypothesized that increased free insulin‐like growth factor (IGF)‐I levels generated from an increase in IGF‐binding protein (IGFBP) protease activity could be the inhibitory mechanism for the decreased growth hormone (GH) secretion observed in obese subjects.

Pegylated Long-Acting Human Growth Hormone Is Well-Tolerated in Healthy Subjects and Possesses a Potential Once-Weekly Pharmacokinetic and Pharmacodynamic Treatment Profile

BACKGROUND Recombinant human GH (rhGH) is usually administered as a daily sc injection, which may be both inconvenient and distressing for patients. NNC126-0083 is a pegylated rhGH developed with the aim of reducing serum clearance and thereby prolonging the exposure leading to once-weekly sc administration. OBJECTIVES In this first human dose trial, the safety, tolerability, pharmacokinetics, and pharmacodynamic parameters of a single administration of NNC126-0083 were evaluated. SUBJECTS AND METHODS Seven groups of eight healthy male volunteers were dosed once with a single sc administration of NNC126-0083 (n = 6) or placebo (n = 2). The doses were escalated between the cohorts in a sequential mode. Blood samples for assessment of safety, pharmacokinetics, and pharmacodynamic response (IGF-I, IGF binding protein-3, free IGF-I) as well as GH binding protein were taken up to 240 h after dosing. RESULTS Seven doses of NNC126-0083 were administered. After NNC126-0083 administration, a significant deviation from pharmacokinetic dose proportionality was observed for the highest doses. A strong dose-dependent pharmacodynamic response was seen with elevated levels of IGF-I and IGF binding protein-3 for all doses administered. The elevation was maintained for more than 1 wk for the highest doses. All doses of NNC126-0083 were well tolerated. No local tolerability issues were identified. CONCLUSION After a single sc administration of NNC126-0083 in healthy male volunteers, a sustained dose-dependent pharmacodynamic response was induced. These results indicate that NNC126-0083 has the potential for an efficacious, well-tolerated, once-weekly rhGH compound in the treatment of GH deficiency in adults.

Pegylated Long-Acting Human Growth Hormone Possesses a Promising Once-Weekly Treatment Profile, and Multiple Dosing Is Well Tolerated in Adult Patients with Growth Hormone Deficiency

BACKGROUND Recombinant human GH (rhGH) replacement therapy in children and adults currently requires daily sc injections for several years or lifelong, which may be both inconvenient and distressing for patients. NNC126-0083 is a pegylated rhGH developed for once-weekly administration. OBJECTIVES Our objective was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple doses of NNC126-0083 in adult patients with GH deficiency (GHD). SUBJECTS AND METHODS Thirty-three adult patients with GHD, age 20-65 yr, body mass index 18.5-35.0 kg/m(2), and glycated hemoglobin of 8.0% or below. Fourteen days before randomization, subjects discontinued daily rhGH. NNC126-0083 (0.01, 0.02, 0.04, and 0.08 mg/kg) was given sc once weekly for 3 wk (NNC126-0083 for six subjects and placebo for two subjects). Blood samples were collected up to 168 h after the first and up to 240 h after the third dosing. Physical examination, antibodies, and local tolerability were assessed. RESULTS NNC126-0083 was well tolerated with no difference in local tolerability compared with placebo and with no signs of lipoatrophy. A more than dose-proportional exposure was observed at the highest NNC126-0083 dose (0.16 mg protein/kg). Steady-state pharmacokinetics seemed achieved after the second dosing. A clear dose-dependent pharmacodynamic response in circulating IGF-I levels was observed [from a predose mean (SD) IGF-I SD score of -3.2 (1.7) to peak plasma concentration of -0.5 (1.3), 1.6 (1.3), 2.1 (0.5), and 4.4 (0.9) in the four dose groups, respectively]. CONCLUSION After multiple dosing of NNC126-0083, a sustained pharmacodynamic response was observed. NNC126-0083 has the potential to serve as an efficacious, safe, and well-tolerated once-weekly treatment of adult patients with GHD.

Polysomnographic sleep, growth hormone insulin-like growth factor-I axis, leptin, and weight loss.

Short sleep appears to be strongly associated with obesity and altered metabolic function, and sleep and growth hormone (GH) secretion seems interlinked. In obesity, both the GH‐insulin‐like‐growth‐factor‐I (GH‐IGF‐I) axis and sleep have been reported to be abnormal, however, no studies have investigated sleep in relation to the GH‐IGF‐I axis and weight loss in obese subjects. In this study polygraphic sleep recordings, 24‐h GH release, 24‐h leptin levels, free‐IGF‐I, total‐IGF‐I, IGF‐binding protein‐3 (IGFBP‐3), acid‐labile subunit (ALS), cortisol and insulin sensitivity were determined in six severely obese subjects (BMI: 41 ± 1 kg/m2, 32 ± 2 years of age), cross‐sectional at baseline, and longitudinal after a dramatically diet‐induced weight loss (36 ± 7 kg). Ten age‐ and gender‐matched nonobese subjects served as controls. Sleep duration (360 ± 17 vs. 448 ± 15 min/night; P < 0.01), 24‐h GH (55 ± 9 vs. 344 ± 55 mU/l·24 h; P < 0.01), free‐IGF‐I (2.3 ± 0.42 vs. 5.7 ± 1.2 μg/l; P < 0.01), and total‐IGF‐I (186 ± 21 vs. 301 ± 18 μg/l; P < 0.01) were significantly decreased and 24‐h leptin levels were increased (35 ± 5 vs. 12 ± 3 μg/l; P < 0.01) in obese subjects at pre‐weight loss compared with nonobese subjects After diet‐induced weight loss the differences in GH, free IGF‐I, and leptin were no longer present between previously obese and nonobese subjects, whereas a significant difference in sleep duration and total IGF‐I levels persisted. Rapid eye movement (REM) sleep, non‐REM sleep, IGFBP‐3, ALS, and cortisol levels were similar in obese and nonobese subjects. Sleep duration, 24‐h GH, and IGF‐I levels were decreased and 24‐h leptin levels were increased in obese subjects. We conclude that hyposomatotropism and hyperleptinemia in obesity are transient phenomena reversible with weight loss, whereas short sleep seems to persist after weight has been reduced dramatically.