Echocardiographic assessment of cardiac morphology and function in mutant dwarf rats

Although the mutant dwarf rat has been proposed as a model of growth hormone (GH) deficiency, few studies have addressed its cardiovascular abnormalities. Therefore, the aim of the present study was to investigate cardiac structure and function in mutant dwarf rats in vivo before and after chronic GH administration, by means of transthoracic Doppler echocardiography. To this purpose, forty 90-day-old female dwarf rats were randomized to receive either GH treatment or placebo. Twenty age-and sex-matched Lewis rats (200-250 g) served as the control group. All rats underwent echocardiograms before receiving any drug and after 3 weeks of therapy. Echocardiographically detected left ventricular mass indexed to tibial length was reduced by 41% in dwarf rats compared to the control group. Such relative cardiac atrophy was also evident at the myocyte level, and was fully reversible after GH therapy. In contrast to the control group, dwarf rats also showed a reduction of left ventricular diastolic volumes normalized to tibial length and impaired cardiac performance as suggested by the reduction of cardiac index, abnormal stress-shortening relations, and a significant elevation of total peripheral vascular resistance. All these abnormalities were reversible upon GH therapy for 3 weeks. In conclusion, GH plays an important role in maintaining a normal cardiac structure and function. Since the observed changes are similar to those seen in GH-deficient men, the mutant dwarf rat represents a faithful animal model of GH deficiency.

[Myocardial metabolism of calcium in heart failure: from physiology to new therapeutic perspectives]

Development of heart failure is associated with an impairment of intracellular calcium handling. The precise mechanisms involved are still obscure. When membrane depolarization occurs, a small amount of extracellular calcium enters the intracellular milieu through the L-type channels. Such "trigger" calcium acts on specific receptors of the sarcoplasmic reticulum, that, in turn, according to the so-called calcium entry-calcium release mechanism, allows the release of a larger amount of calcium from the sarcoplasmic reticulum. Removal of calcium from the cytosol is the key event of the diastolic phase. Calcium removal from cytosol occurs through specific membrane pumps. Recent therapeutic approaches involving gene targeting of calcium pumps have yielded promising results. Specifically, increased levels of SERCA 2 in the myocardium have shown to enhance cardiac contractility under normal circumstances and in experimental heart failure. Future research is needed to confirm these findings in human heart failure.

Growth hormone (GH) effects on bone and collagen turnover in healthy adults and its potential as a marker of GH abuse in sports: a double blind, placebo-controlled study. The GH-2000 Study Group

The effects of GH on bone remodeling in healthy adults have not been systematically investigated. An analysis of these effects might provide insights into GH physiology and might yield data useful for the detection of GH doping in sports. The aim of this study was to evaluate the effects of GH administration on biochemical markers of bone and collagen turnover in healthy volunteers. Ninety-nine healthy volunteers of both sexes were enrolled in a multicenter, randomized, double blind, placebo-controlled study and assigned to receive either placebo (40 subjects) or recombinant human GH (0.1 IU/kg day in 29 subjects and 0.2 IU/kg x day in 30 subjects). The treatment duration was 28 days, followed by a 56-day wash-out period. The biochemical markers evaluated were the bone formation markers osteocalcin and C-terminal propeptide of type I procollagen, the resorption marker type I collagen telopeptide, and the soft tissue marker procollagen type III. All variables increased on days 21 and 28 in the two active treatment groups vs. levels in both the baseline (P < 0.01) and placebo (P < 0.01) groups. The increment was more pronounced in the 0.2 IU/kg-day group and remained significant on day 84 for procollagen type III (from 0.53 +/- 0.13 to 0.61 +/- 0.14 kU/L; P < 0.02) and osteocalcin (from 12.2 + 2.9 to 14.6 +/- 3.6 UG/L; P < 0.02), whereas levels of C-terminal propeptide of type I procollagen and type I collagen telopeptide declined after day 42 and were no longer significantly above baseline on day 84 (from 3.9 +/- 1.2 to 5.1 +/-1.5 microg/L and from 174 +/- 60 to 173 +/- 53 microg/L, respectively). Gender-related differences were observed in the study; females were less responsive than males to GH administration with respect to procollagen type III and type I collagen telopeptide (P < 0.001). In conclusion, exogenous GH administration affects the biochemical parameters of bone and collagen turnover in a dose- and gender-dependent manner. As GH-induced modifications of most markers, in particular procollagen type III and osteocalcin, persist after GH withdrawal, they may be suitable markers for detecting GH abuse.

Responses of markers of bone and collagen turnover to exercise, growth hormone (GH) administration, and GH withdrawal in trained adult males

To examine the interactions between acute exercise and GH on markers of bone and collagen turnover and to assess the potential for detecting GH abuse in athletes using these markers, we studied 17 aerobically trained males (age, 26.9+/-1.5 yr). Sequential studies of exercise, GH administration, and GH withdrawal were undertaken. A randomized, controlled study of rest vs. exercise showed that exercise did not change serum osteocalcin; other markers of formation increased transiently (each P<0.001): bone-specific alkaline phosphatase (+16.1%), carboxyterminal propeptide of type I procollagen (+14.1%), and procollagen III N-terminal extension peptide (+5.0%). The carboxyterminal cross-linked telopeptide of type I collagen, a bone resorption marker, increased 9.7% (P = 0.018) in response to exercise. A randomized, double blind, placebo-controlled, parallel study of recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum osteocalcin (net increase preexercise, +/-10.0%; P = 0.017), carboxyterminal propeptide of type I procollagen (+17.6%; P = 0.002), procollagen III N-terminal extension peptide (+48.4%; P = 0.001), and carboxyterminal cross-linked telopeptide of type I collagen (53.3%; P = 0.009). Disappearance half-times after cessation of recombinant human GH for pre- and postexercise markers ranged from 248-770 h. We conclude 1) endurance exercise transiently activates bone and collagen turnover; 2) brief GH administration results in similar but quantitatively greater augmentation; and 3) these data will assist in designing a GH detection strategy.

Responses of the growth hormone (GH) and insulin-like growth factor axis to exercise, GH administration, and GH withdrawal in trained adult males: a potential test for GH abuse in sport

GH abuse by elite athletes is currently undetectable. To define suitable markers of GH doping, we assessed the effects of acute exercise, GH administration, and GH withdrawal on the GH/insulin-like growth factor (IGF) axis in athletic adult males. Acute endurance-type exercise increased serum GH, GH-binding protein (GHBP), total IGF-I, IGF-binding protein (IGFBP)-3, and acid-labile subunit (ALS), each peaking at the end of exercise. IGFBP-1 increased after exercise was completed. Free IGF-I did not change with exercise. Recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum total IGF-I, IGFBP-3, and ALS, exaggerating the responses to exercise. IGFBP-2 and IGFBP-1 were trivially suppressed. After GH withdrawal, the GH response to identical exercise was suppressed. Total IGF-I, IGFBP-3, and ALS returned to baseline over 3-4 days. In summary, 1) acute exercise transiently increased all components of the IGF-I ternary complex, possibly due to mobilization of preformed intact complexes; 2) GH pretreatment augmented the exercise-induced changes in ternary complexes; 3) postexercise IGFBP-1 increments may protect against delayed onset hypoglycemia; 4) serum total IGF-I, IGFBP-3, and ALS may be suitable markers of GH abuse; and 5) differences in disappearance times altered the sensitivity of each marker for detecting GH abuse.

Effects of two years of growth hormone (GH) replacement therapy on bone metabolism and mineral density in childhood and adulthood onset GH deficient patients

The aim of the current study was to evaluate bone metabolism and mass before and after 2 years of GH replacement therapy in adults with childhood or adulthood onset GH deficiency. Thirty-six adults with GH deficiency, 18 with childhood onset, 18 with adulthood onset GH deficiency and 28 sex-, age-, height- and weight-matched healthy subjects entered the study. Biochemical indexes of bone turnover such as serum osteocalcin, serum carboxyterminal telopeptide of type-I procollagen, urinary hydroxyproline/creatinine and deoxypyridinoline/creatinine, of soft tissue formation such as aminoterminal propeptide of type-III and bone mineral density were evaluated. Childhood onset GH deficient patients had significantly decreased bone (osteocalcin: 2.5+/-1.3 vs 6.6+/-4.8 mcg/l, p<0.001) and soft tissue formation (aminoterminal propeptide of type III: 273+/-49 vs 454+/-23 U/I, p<0.001) indexes and normal bone resorption indexes (serum carboxyterminal telopeptide of type-I procollagen: 105+/-48 vs 128+/-28 mcg/l p=NS; urinary hydroxyproline/creatinine: 0.19+/-0.16 vs 0.28+/-0.16 mmol/mol, p=NS; urinary deoxypyridinoline/creatinine: 21 +/-10 vs 25+/-8 mcmol/mol, p=NS) compared to healthy subjects. On the contrary, no significant difference in bone turnover indexes between adulthood onset GH deficient patients and healthy subjects was found. Moreover, significantly decreased bone mineral density at any skeletal site and at whole skeleton was found in GH deficient patients compared to healthy subjects (e.g. femoral neck: 0.74+/-0.13 vs 0.97+/-0.11 g/cm2, p<0.001). In addition, a significant reduction of bone mineral density was found in childhood compared to adulthood onset GH deficient patients at any skeletal site, except at femoral neck. After 3-6 months of treatment, both groups of patients had a significant increase in bone turnover and in soft tissue formation. In particular, in childhood onset GH deficient patients after 3 months osteocalcin increased from 2.5+/-1.3 to 7.9+/-2.1 mcg/l, p<0.001 aminoterminal propeptide of type-III from 273+/-49 to 359+/-15 U/I p<0.001; serum carboxyterminal telopeptide of type-I procollagen from 105+/-48 to 201+/-45 mcg/l, p<0.001; urinary hydroxyproline/creatinine from 0.19+/-0.16 to 0.81+/-0.17 mmol/mol, p<0.001; urinary deoxypyridinoline/creatinine from 21 +/-10 to 54+/-20 mcmol/mol, p<0.001; while in adulthood onset GH deficient patients after 6 months osteocalcin increased from 4.2+/-3.6 to 6.5+/-1.9 mcg/l, p<0.05; aminoterminal propeptide of type- III from 440+/-41 to 484+/-37 U/I, p<0.05; serum carboxyterminal telopeptide of type-I procollagen from 125+/-40 to 152+/-22 mcg/l, p<0.05; urinary hydroxyproline/creatinine from 0.24+/-0.12 to 0.54+/-0.06 mmol/mol, p<0.001; urinary deoxypyridinoline/creatinine from 23+/-8 to 42+/-5 mcmol/mol, p<0.001. No significant difference in bone turnover between pre- and post-treatment period was found after 18-24 months of GH therapy. Conversely, bone mineral density was slightly reduced after 3-6 months of GH therapy, while it was significantly increased after 18-24 months. In fact, femoral neck bone mineral density values significantly rose from 0.74+/-0.13 g/cm2 to 0.87+/-0.11 g/cm2 (pre-treatment vs 2 years of GH treatment values). In conclusion, patients with childhood or adulthood onset GH deficiency have osteopenia that can be improved by long-term treatment with GH.

Growth hormone and the heart

Until a few years ago, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were considered essential only to the control of linear growth, glucose homeostasis, and for the maintenance of skeletal muscle mass. A large body of evidence recently coming from animal and human studies has unequivocally proven that the heart is a target organ for the GH/IGF-1 axis. Specifically GH exerts both direct and indirect cardiovascular actions. Among the direct effects, the ability of GH to trigger cardiac tissue growth plays a pivotal role. Another direct effect is to augment cardiac contractility, independent of myocardial growth. Direct effects of GH also include the improvement of myocardial energetics and mechanical efficiency. Indirect effects of GH on the heart include decreased peripheral vascular resistance (PVR), expansion of blood volume, increased glomerular filtration rate, enhanced respiratory activity, increased skeletal muscle performance, and psychological well-being. Among them, the most consistently found is the decrease of PVR. GH may also raise preload through its sodium-retaining action and its interference with the hormonal system that regulates water and electrolyte metabolism. Particularly important is the effect of GH on skeletal muscle mass and performance. Taking into account that heart failure is characterized by left ventricular dilation, reduced cardiac contractility, and increase of wall stress and peripheral vascular resistance, GH may be beneficial for treatment of heart failure. Animal studies and preliminary human trials have confirmed the validity of the GH approach to the treatment of heart failure. Larger placebo-controlled human studies represent the main focus of future investigations.

Bone mineral density and circulating cytokines in patients with acromegaly

Acromegalic patients present an increase of osteoblastic and osteoclastic activity, showing a different effect on the axial and appendicular skeletal structures. At this regard controversial data about bone mineral density (BMD) have been published in literature. In fact an increase of BMD levels in femoral neck and Ward's triangle without any difference in lumbar spine has been described. On the other hand normal BMD levels at forearm and reduced BMD levels at lumbar spine were found. These patients seem to have a reduction of trabecular BMD similar to postmenopausal osteoporotic patients despite normal or slightly elevated cortical BMD. Recently, it has been described that cytokines, in particular tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1), are implicated in the pathogenetic mechanism of postmenopausal osteoporosis. Taking into account that growth hormone (GH) can increase TNF-alpha and IL-1 secretion by mononuclear blood cells, the evaluation of possible relationship between the reduced BMD at lumbar spine and circulating cytokines levels was carried out in acromegalic patients. In addition we evaluated the effect of acute octreotide administration on serum TNF-alpha and IL-I concentrations. Eleven patients with active acromegaly and eleven healthy age-, sex-, weight- and heightmatched subjects were enrolled in this study. BMD was significantly reduced at lumbar spine (0.80 +/- 0.29 g/cm2 vs 1.02 +/- 0.11 g/cm2; p < 0.01), but not at femoral neck level or at Ward's triangle level (0.92 + 0.15 g/cm2 vs 0.97 + 0.11 g/cm2, p = NS; and 0.74 +/- 0.16 g/cm2 vs 0.85 +/- 0.1 g/cm2, p = NS) when compared to controls. Baseline serum levels of TNF-alpha and IL-1 were in the normal range both in patients and controls. After acute octreotide administration, no differences in circulating TNF-alpha and IL-1 levels were found. In conclusion, acromegalic patients present a reduced BMD at lumbar spine but not at femoral neck level and Ward's triangle. Circulating cytokines such as TNF-alpha and IL-1 are in the normal range. These data suggest that cytokines are not involved in the pathogenesis of GH-excess induced osteoporosis. The possibility that the GH excess might affect bone turnover inducing an increase of cytokines acting by a paracrine/autocrine mechanism cannot be ruled out.

Height, weight, height velocity of primary school population sample in Campania region

Aim of this study was to plot height, weight and height velocity values of primary school civic population of Portici and Ercolano, Campania towns, on Tanner's charts in order to verify the overlapping of percentile distribution. On May 1994 height and weight were measured in 3504 children (1735 boys and 1769 girls, aged 5.4-16.1 years, mean age = 8.6 years) from the 1st, 2nd and 5th year of primary schools in Portici and Ercolano. One year later, on May 1995, we remeasured and reweighed 1583 (781 boys and 802 girls, aged 6.4-14.2 years, mean age = 9.6 years) out of total children and we calculated height velocity (HV). The height and weight profiles of our population sample show that children in Portici and Ercolano are taller and fatter than those measured by Tanner and Whitehouse 25-30 years ago. The calculation of body mass index (BMI) confirmed that 30% of total children were obese. Furthermore, the evaluation of one-year HV revealed a clear improvement of linear growth. Our data suggest that Tanner and Whitehouse charts should be updated, and it should be useful to elaborate also height, weight and HV standards derived from present-day population.

Left ventricular function in young adults with childhood and adulthood onset growth hormone deficiency

OBJECTIVE

The impairment of heart structure and function in adults with childhood onset GH deficiency has been recently described. However, previous echocardiographic studies have reported no differences in cardiac mass and function between adulthood onset GH deficient patients and healthy subjects.

DESIGN

The aim of this study was to evaluate cardiac performance in adult patients with childhood and adulthood onset GH deficiency, using equilibrium radionuclide angiography, a method more accurate than echocardiography.

PATIENTS

Eleven patients with childhood onset GH deficiency, 9 patients with adulthood onset GH deficiency and 12 age-, gender-, height- and weight-matched healthy subjects entered the study.

MEASUREMENTS

All the study population underwent equilibrium radionuclide angiography at rest and during physical exercise.

RESULTS

Both childhood and adulthood onset GH deficient patients had an impaired left ventricular systolic performance both at rest (ejection fraction was 55 +/- 6%, 55 +/- 10% and 66 +/- 6% in childhood and adulthood onset GH deficient patients and control group, respectively; P < 0.0001) and during physical exercise (ejection fraction was 54 +/- 9% in childhood onset GH deficient patients, 53 +/- 9% in adulthood onset GH deficient patients and 76 +/- 7% in normal subjects; P < 0.0001). Peak ejection rate was 3.2 +/- 0.8 end-diastolic volume/second, 3.0 +/- 0.6 end-diastolic volume/second and 3.9 +/- 0.8 end-diastolic volume/ second in childhood and adulthood onset GH deficient patients and control group, respectively (P < 0.01). Exercise-induced changes in end-systolic volume were increased in both groups of patients compared with healthy subjects. In contrast, exercise-induced end-diastolic volume changes were not different between GH deficient patients and controls. Resting peak filling rate was 2.6 +/- 0.7 end-diastolic volume/second, 2.5 +/- 0.7 end-diastolic volume/ second and 3.1 +/- 0.3 end-diastolic volume/second in the 2 groups of patients and healthy subjects, respectively (P < 0.05). Reduced exercise tolerance in all patients, as shown by the significantly lower values of peak workload (P < 0.0001), peak rate-pressure product (P < 0.01) and exercise duration (P < 0.0001) was observed.

CONCLUSION

Patients affected by GH deficiency have left ventricular systolic dysfunction at rest and during physical exercise, suggesting that GH plays a physiological role in maintaining normal cardiac performance in humans. Furthermore, no difference between childhood and adulthood onset GH deficient patients was found indicating that both group of patients have an impairment of cardiac function.

Effect of growth hormone on cardiac function

At present, there is a growing body of evidence implicating growth hormone (GH) and/or insulin-like growth factor-I (IGF-I) in the intricate cascade of events connected with the regulation of heart development and hypertrophy. In addition, advanced clinical manifestations of abnormal GH levels almost always include impaired cardiac function, which may reduce life expectancy. This finding is related both to a primary impairment of heart structure and function and to metabolic changes such as hyperlipidaemia, increased body fat and premature atherosclerosis. Acromegalic cardiomyopathy is better correlated with disease duration than with GH or IGF-I levels. Myocardial hypertrophy with interstitial fibrosis, lymphomononuclear infiltration and areas of monocyte necrosis often result in increased right and left ventricular mass concentric hypertrophy. Conversely, patients with childhood or adult-onset GH deficiency (GHD) have a reduced left ventricular mass (LVM) and ejection fraction (EF) and the indices of left ventricular systolic function remained markedly depressed during exercise. Cardiac function is reported to improve during octreotide and GH replacement treatment in acromegaly and GHD, respectively. The evidence that GH can increase cardiac mass suggests its use in the treatment of idiopathic dilated cardiomyopathy. In a recent study on such patients, the administration of recombinant GH (rGH) was demonstrated to increase myocardial mass and reduce the size of the left ventricular chamber, resulting in improved haemodynamics, myocardial energy metabolism and clinical status.

Short stature and azoospermia in a patient with Y chromosome long arm deletion

We report on a 42-year old male with short stature, azoospermia and a wide deletion of long arm of Y chromosome. On physical examination, the patient showed height of 149 cm (< 1 degree centile) and reduced volume (3 ml) and consistency of the testes. On hormonal evaluation, he showed increased serum gonadotropins and normal serum testosterone levels though its HCG stimulated levels were limited. Serum thyroid hormones were normal. Serum GH levels in baseline evaluation as well as after GHRH and GHRH + pyridostigmine administration were normal. Serum IGF I levels were lower than normal in baseline evaluation whereas its response to the GH administration was in the normal range. The bilateral testicular biopsy showed tubular atrophy, hyalinosis, interstitial sclerosis and a histological picture of a Sertoli cell only syndrome. Moreover the patient showed arthropathy, otopathy, small chin, small mouth and truncal obesity. On genetic evaluation, the patient showed a 46,X,delY (pter--q11.1:) karyotype and loss of several DNA loci on Yq. In fact he preserved short arm SRY, centromeric DYZ3 and more proximal euchromatic region Yq loci, including DYS270, DYS271, DYS272, DYS11, DYS273, DYS274, DYS148, DYS275, and missed more distal DNA loci from DYS246 to DYZ2. These results disclosed a wide Y long arm deletion, including all hypothized Yq azoospermia loci (except for AZFa and probably for one of the RBM genes, which lie proximally to the deletion) and possibly the Y-specific growth control region (GCY), mapped between DYS11 and DYS246 loci. This deletion is responsible for the complete azoospermia of the patient and probably also for his short stature, even if other factors could be implicated in the statural impairment. It further possibly allowed to relate the GCY gene(s) to the control of GH or IGF-I receptor or post-receptor pathway, being the alteration of this gene(s) consistent with the hormonal pattern of the patient.

Cardiological aspects of growth hormone and insulin-like growth factor-I

In recent years it has been demonstrated that both GH deficiency and excess include in their advanced clinical manifestations an impaired cardiovascular function, which may reduce life expectancy. This observation has allowed the investigation of the role played by the GH/IGF-I axis on cardiac structure and function. In particular, several recent experimental and clinical studies support the evidence implicating GH and/or IGF-I in the regulation of heart development. Acromegalic cardiomyopathy is characterized by myocardial hypertrophy with interstitial fibrosis, lymphomononuclear infiltration and areas of monocyte necrosis which often result in increased right and left ventricular mass and concentric hypertrophy. Conversely, patients with childhood or adulthood-onset GH deficiency (GHD) have a reduced left ventricular mass and ejection fraction and the indexes of left ventricular systolic function remained markedly depressed during exercise. In addition, a significant increase in the thickness of the vascular intima-media wall and a higher number of atheromatous plaques have been reported. These abnormalities of the cardiovascular system are partially reversed after normalization of GH and IGF-I levels, by octreotide in acromegaly or after GH replacement therapy in GHD patients. The evidence that GH is able to increase cardiac mass suggested its use in the treatment of idiopathic dilated cardiomyopathy. In a recent study on such patients, the administration of rhGH was demonstrated to increase myocardial mass and to reduce the size of the left ventricular chamber, resulting in an improvement in hemodynamics, myocardial energy metabolism and clinical status. These promising results might open a new field for GH treatment.

Is growth hormone bad for your heart? Cardiovascular impact of GH deficiency and of acromegaly

At present, there is growing evidence implicating GH and/or IGF-I in the intricate cascade of events connected with the regulation of heart development and hypertrophy. Moreover, GH excess and/or deficiency have been shown to include in their advanced clinical manifestations almost always an impaired cardiac function, which may reduce life expectancy. This finding is related both to a primitive impairment of heart structure and function and to metabolic changes such as hyperlipidemia, increase of body fat and premature atherosclerosis. Patients with childhood or adulthood-onset GH deficiency have a reduced left ventricular mass and ejection fraction and the indexes of left ventricular systolic function remain markedly depressed during exercise. Conversely, in acromegaly the cardiac enlargement, which is disproportionate to the increase in size of other internal body organs, has been a rather uniform finding. The severity of the acromegalic cardiomyopathy was reported to be correlated better with the disease duration than with circulating GH and/or IGF-I levels. Myocardial hypertrophy with interstitial fibrosis, lymphomononuclear infiltration and areas of monocyte necrosis often results in concentric hypertrophy of both ventricles. The treatment of GH deficiency and excess improved cardiac function. Interestingly, based on the evidence that GH increases cardiac mass, recombinant GH was administered to patients with idiopathic dilated cardiomyopathy. It increased the myocardial mass and reduced the size of the left ventricular chamber, resulting in improvement of hemodynamics, myocardial energy metabolism and clinical status. These promising results open new perspectives for the use of GH in heart failure.

Increased arterial intima-media thickness in childhood-onset growth hormone deficiency

Very little is known about the atherosclerotic risk in patients with childhood-onset growth hormone deficiency (GHD). Such data may be relevant to reconstructing the natural course of the cardiovascular abnormalities associated with GHD. To this end, the intima-media thickness (IMT) of the carotid arteries and the vascular risk factors were evaluated in 14 childhood-onset GHD patients (age 25 +/- 1 yr, BMI 22 +/- 0.6 Kg/m2) and in 14 age-, sex-, and BMI-matched control subjects. IMT was greater in GHD patients (0.83 +/- 0.06 and 0.81 +/- 0.06 mmol/L for the right and left carotid artery) than in controls (0.64 +/- 0.03 and 0.64 +/- 0.04 mmol/L, P < 0.01 and P < 0.02, respectively). Serum total and lipoprotein cholesterol, and serum total triglycerides did not differ between the two groups. However, a significant increase in low density lipid triglycerides was present in GHD patients (0.27 +/- 0.02 mmol/L) compared with controls (0.19 +/- 0.01; P = 0.007). No difference was found in plasma fibrinogen and serum Lp(a) levels. Plasma glucose and insulin concentrations were similar in GHD and control subjects both in the fasted state and after an oral glucose load. In conclusion, young patients with childhood-onset GHD show an increased IMT in the absence of clear-cut abnormalities of the classic vascular risk factors. This suggests a role for GH deficiency per se in increasing the atherosclerotic risk.

Growth hormone and heart performance. A novel mechanism of cardiac wall stress regulation in humans

OBJECTIVES

This study was designed to assess systolic wall stress and ventricular function in patients with deranged growth hormone secretion, in an attempt to elucidate the mechanisms of growth hormone interaction with heart performance.

DESIGN

A case-control study.

SUBJECTS

Thirty patients with active acromegaly, free of diabetes mellitus and coronary artery disease, and 25 subjects with congenital growth hormone deficiency were studied. Twelve growth hormone-deficient subjects were reevaluated after 12 months of recombinant human growth hormone therapy. Two groups of 30 normal subjects each were used as controls for the acromegalic and growth hormone-deficient patients, respectively.

RESULTS

In the acromegalics, end-systolic wall stress was reduced (-20%; P < 0.01) due to ventricular wall thickening (+ 26%; P < 0.001), whereas cardiac output was significantly increased (+ 20%; P < 0.01). The velocity of fibre shortening was unchanged. In growth hormone-deficient subjects, end-systolic wall stress was markedly increased (+ 38%; P < 0.001) due to a significant reduction of ventricular wall thickness (- 28%; P < 0.001), whereas cardiac output was significantly decreased (-44%; P < 0.001). Replacement therapy with recombinant human growth hormone produced a partial correction of wall thickness and stress. Consequently, systolic performance and cardiac output improved significantly.

CONCLUSION

This study demonstrates that growth hormone plays a role in the control of cardiac wall stress and performance through a mechanism mediated by the effect of growth hormone on myocardial tissue growth. The data may have therapeutic implications in cardiac diseases that lead to heart failure.

Lung volumes and respiratory muscle strength in adult patients with childhood- or adult-onset growth hormone deficiency: effect of 12 months' growth hormone replacement therapy

We have described impairment of the respiratory function in adult patients with childhood-onset growth hormone (GH) deficiency. The aim of the present study was to evaluate lung volumes and respiratory muscle strength in patients diagnosed as GH deficient before and after 6 and 12 months of recombinant GH treatment. Ten adults diagnosed as GH deficient in childhood, ten adults diagnosed as GH deficient in adulthood and ten healthy subjects entered the study. For each subject, evaluation of respiratory function followed the same standard approach, consisting of respiratory muscle strength assessment, record of flow-volume curves, measurement of static lung volumes and lung diffusing capacity. Childhood-onset GH-deficient patients had a significant reduction of maximal inspiratory (p < 0.01) and maximal expiratory (p < 0.05) mouth pressures. Total lung capacity, vital capacity and functional residual capacity were significantly reduced compared to healthy subjects (p < 0.05). Conversely, residual volume and diffusing lung capacity did not show any significant change. No significant change of the ratio between the percentage forced expiratory volume in 1 s and the forced vital capacity was observed. The decrease of respiratory mouth pressures was not correlated to the decrease of lung volumes. Adult-onset GH-deficient patients had only a significant reduction of maximal expiratory pressure compared to healthy subjects (p < 0.05). After 6 months of treatment no significant differences in any of the evaluated parameters were found. After 12 months of treatment patients with childhood-onset GH deficiency show a significant improvement of lung volumes (p < 0.01) and maximal respiratory mouth pressures (p < 0.005), whereas adult-onset GH-deficient patients show a significant improvement of maximal expiratory pressure (p < 0.05). In conclusion, the results of this study showed that adult patients affected with childhood-onset GH deficiency suffer from an impairment of the ventilatory function due to a reduction of lung volumes and a decrease of respiratory pressures probably due to a reduction of respiratory muscle strength. This impairment was reversed after 12 months of treatment with recombinant GH. Conversely, adult-onset GH-deficient patients had only an impairment of the maximal expiratory pressure, probably due to respiratory muscle weakness re-established after 12 months of GH therapy.

Tumor necrosis factor-alpha increases after corticotropin-releasing hormone administration in Cushing's disease. In vivo and in vitro studies

The aim of this study was to evaluate the effect of acute human corticotropin (ACTH)-releasing hormone (CRH) administration (100 micrograms, as i.v. bolus) on tumor necrosis factor-alpha (TNF alpha) levels in the inferior petrosal sinuses and in the peripheral blood of 7 patients with Cushing's disease subjected to diagnostic inferior petrosal sinus sampling. Blood samples for ACTH, beta-endorphin (beta-EPH) and TNF alpha were collected from inferior petrosal sinuses and periphery simultaneously. In addition, TNF alpha concentrations were measured after CRH administration (10 nmol/l, 100 nmol/l and 1 mumol/l) in culture medium from primary cultures obtained in 3 of 7 patients. At baseline, plasma ACTH and beta-EPH levels were significantly higher in the inferior petrosal sinus ipsilateral to the ACTH-secreting adenoma than in the contralateral one and in the periphery (p < 0.001) whereas no significant difference was found as far as serum TNF alpha levels were concerned. CRH administration caused a significant increase of ACTH (p < 0.001), beta-EPH (p < 0.01) and TNF alpha (p < 0.01) levels greater in the ipsilateral inferior petrosal sinus than in the contralateral one and in the periphery. In addition, CRH increased ACTH, beta-EPH and TNF alpha levels in the culture medium of three ACTH-secreting tumors at the doses of 100 nmol/l and 1 mumol/l (greater than 300, 200 and 110% of baseline pretreatment incubation levels, respectively). These data suggest that CRH may increase TNF alpha concentrations in the inferior petrosal sinus ipsilateral to the ACTH-secreting adenoma and in the peripheral blood as well. In addition, it stimulated TNF alpha release both in vivo and in vitro. These findings suggest the possibility that an imbalanced intrapituitary TNF alpha production can be detected in ACTH-secreting adenomas.

Cardiovascular aspects in acromegaly: effects of treatment

Patients with acromegaly have significant morbidity and mortality, associated with cardiovascular disease. Acromegaly is often complicated by other diseases such as diabetes mellitus, hypertension, and coronary artery disease, so the existence of acromegalic cardiomyopathy remains uncertain. Cardiac performance was investigated in patients with uncomplicated acromegaly. A subgroup of hypertensive acromegalics was also studied. In addition, the effects of chronic octreotide therapy or surgery on cardiac structure and function in acromegaly were studied. Twenty-six patients and 15 healthy controls underwent gated blood-pool cardiac scintigraphy and echocardiography at rest and during exercise. Echocardiography was repeated after 6 months of octreotide therapy (n = 11). Cardiac scintigraphy was repeated after 12 and 24 months of octreotide therapy (n = 10) or 12 to 24 months after surgery (n = 8). ECG, blood pressure, and heart rate were monitored during cardiac scintigraphy. Left ventricular mass (LVM) was calculated from the findings of the echocardiography. Serum growth hormone (GH) levels and plasma insulin-like growth factor-1 (IGF-1) levels were monitored. LVM index was significantly higher (P < .003) in acromegalics than controls and in hypertensive acromegalics than normotensives, but all other indices of cardiac function were similar. Chronic octreotide decreased GH and IGF-1 levels and improved the structural abnormalities as measured by echocardiography. Chronic octreotide or surgery did not alter cardiac function parameters. Thus, important changes in cardiac structure and function occur in uncomplicated acromegaly, and improvements can be demonstrated after chronic octreotide therapy. Heart disease in acromegaly appears to be secondary to high circulating GH levels.

Prediction of efficacy of octreotide therapy in patients with acromegaly

Octreotide (OCT) administration provides a biochemical cure in most acromegalic patients. This drug, however, causes several side effects and is very expensive. Acute testing has been reported to predict chronic responsiveness to OCT administration. The aim of this retrospective study was to evaluate which test, if any, among acute testing, short-term (1 month) administration, and 111In-pentetreotide (111In-DTPA-Phe-D-OCT) scintigraphy, is best in predicting response to long-term OCT treatment. Sixty-eight patients with active acromegaly were studied. An acute test (100 micrograms sc OCT) was performed as usual: a GH decrease greater than or equal to 50% of baseline was considered a positive response. GH and insulin-like growth factor I (IGF-I) were then assayed after 1 month (300 micrograms daily) and 3 months (150-600 micrograms daily) of OCT administration. GH was considered normalized when decreased less than or equal to 5 micrograms/L. Twenty-six of 68 patients were subjected to 111In-pentetreotide scintigraphy. Linear correlation analysis of the results was performed. Sensitivity, specificity, and positive and negative predictive values of the three tests were also calculated. Thirty-eight of 68 patients (56%) responded to the acute test. Among these 38 patients, 20 experienced normalization of GH and IGF-I levels during long-term therapy, as did 8 patients who did not respond to the acute test. No significant correlation was found between GH percent decrease during acute testing and long-term therapy (r = 0.11). Seven patients who responded to the acute test and 2 who did not respond had adenoma shrinkage during therapy. Conversely, GH and IGF-I decrease after short-term treatment significantly correlated with long-term treatment (r = 0.76 and 0.64, P < 0.01). Of the 26 patients subjected to 111In-pentetreotide scintigraphy, 13 had significant tracer uptake: normalization of GH and IGF-I was obtained in 8 patients. A significant correlation was found between tracer uptake and GH/IGF-I inhibition after 3 months of therapy (r = 0.6; P < 0.05). In the whole population, the positive predictive value of acute testing, short-term OCT administration, and 111In-penetreotide scintigraphy was 53%, 70%, and 73%, respectively, when the GH normalization (< 5 micrograms/L) after 3 months of therapy was considered. Moreover, 111-In-pentetreotide scintigraphy had the highest specificity (100% in patients with baseline GH values below 50 micrograms/L) compared with that of acute testing and short-term OCT administration. The acute test cannot be considered as a valuable index to identify patients' responsiveness to long-term OCT therapy, but it can be useful to test tolerability. By contrast, 1 month of OCT administration or the in vivo imaging of somatostatin receptors by 111-In-pentetreotide might better indicate the patients who might effectively benefit from this treatment.

Improved left ventricular function after growth hormone replacement in patients with hypopituitarism: assessment with radionuclide angiography

Prolonged growth hormone deficiency (GHD) leads to marked cardiac dysfunction; however, whether reversal of this abnormality may be achieved after specific replacement therapy has not yet been completely clarified. Fourteen patients with childhood-onset GHD (nine men and five women, mean age 27+/-4 years) and 12 normal control subjects underwent equilibrium radionuclide angiography under control conditions at rest. Patients with GHD were also studied 6 months after recombinant human (rh) GH treatment (0.05 IU/kg per day). Normal control subjects and patients with GHD did not differ with respect to age, gender and heart rate. In contrast, left ventricular ejection fraction (53%+/-9% vs 66%+/-6%, P <0.001), stroke volume index (41+/-11 vs 51+/-8 ml/m2, P <0.01) and cardiac index (2.8+/-0.6 vs 3.+/-0.5 l/min/m2, P <0.001) were significantly lower in GHD patients than in normal control subjects. None of the GHD patients showed adverse or side-effects during rhGH therapy; thus none required a reduction in GH dose during the treatment period. Heart rate and arterial blood pressure were not significantly modified by rhGH treatment. After 6 months of rhGH therapy a significant improvement in left ventricular ejection fraction (from 53%+/-9% to 59%+/-9%, P <0.01), stroke volume index (from 41+/-11 to 47+/-13 ml/m2, P <0.05) and cardiac index (from 2.8+/-0.6 to 3.3+/-0.8 l/min/m2, P <0.01) was observed in GHD patients. In conclusion, prolonged lack of GH leads to impaired left ventricular function at rest. Reversal of this abnormality may be observed after 6 months of specific replacement therapy in patients with childhood-onset GHD.

Reevaluation of growth hormone (GH) secretion in 69 adults diagnosed as GH-deficient patients during childhood

At present, the most appropriate method for diagnosing GH deficiency (GHD) in adults remains unclear. Recently, it has been demonstrated that GHD in adults can be identified by insulin tolerance test (ITT). Moreover, it has been described that the GHRH plus pyridostigmine (GHRH+PD) test is more accurate than an arginine, glucagon, levodopa, or GHRH test to diagnose GHD in adults. In the current study, firstly we reevaluated GH secretion by the GHRH+PD test in adults previously diagnosed as GH deficient in childhood. The study included 69 patients and 38 healthy subjects. After the GHRH+PD test, the patients and the healthy subjects had peak GH levels of 10.6 +/- 11.2 and 56.7 +/- 28.1 micrograms/L, respectively (P < 0.001). The patients were divided into two groups, responder patients and nonresponder patients, considering an arbitrary cut-off of 10 micrograms/L as the GH peak after the GHRH+PD test. Thirty-nine patients had GH peak below 10 micrograms/L (1.9 +/- 1.7 micrograms/L), whereas the remaining 30 patients above 10 micrograms/L (21.6 +/- 8.] micrograms/L; P < 0.001). Secondly, we compared the GHRH+PD test and the ITT in diagnosing GHD. Twenty-one of the 39 patients with a GH peak below 10 micrograms/L and 29 of the 30 patients with a GH peak above 10 micrograms/L after the GHRH+PD test underwent an ITT. The GH peak after insulin administration was 2.1 +/- 1.7 micrograms/L in nonresponder patients and 21.1 +/- 9.3 micrograms/L in responder patients after the GHRH+PD test (P < 0.001). Three of the responder patients to the GHRH+PD test were identified as GH deficient by the ITT. The relative diagnostic accuracies of the two tests to discriminate GH-deficient patients from healthy subjects were similar (ITT vs. GHRH test: sensitivity, 100%, specificity, 90%; GHRH+PD vs. ITT; sensitivity, 88%; specificity, 100%). In conclusion, in adults previously diagnosed as GH deficient, it is mandatory to reevaluate GH secretion. GHRH+PD and/or ITT are able to diagnose GHD in adults with similar accuracies. Taking into account the potential side-effects of the ITT, however, the GHRH+PD test is the most reliable and safe test to accurately diagnose GHD status in adults.