D. Valle

Leptin Stimulates Growth Hormone Secretion via a Direct Pituitary Effect Combined with a Decreased Somatostatin Tone in a Median Eminence-Pituitary Perifusion Study

The aim of this study was to examine the effect of recombinant human leptin on growth hormone (GH) secretion in perifused anterior pituitary slices from adult pigs. Anterior pituitary slices from sows were perifused and treated with recombinant human leptin (10 nM) and GH-releasing hormone (GHRH; 1 nM). In some experiments, pituitary slices were coincubated with stalk median eminence (SME). In a subset of the coincubation experiments, immunoneutralization of endogenous GHRH and somatostatin (SRIH) release was performed with antisera to GHRH and SRIH. Leptin increased GH secretion in pituitary slices alone (up to 100% vs. control at 40 min) as well as in pituitary slices coincubated with SME (up to 122% vs. control at 40 min). A significant difference was observed in GH secretion from pituitary slices when the tissue was coincubated with leptin and GHRH at a low concentration (0.1 nM), but not when GHRH was used at 1 and 10 nM. Furthermore, anti-SRIH antiserum increased GH release from pituitary slices in coincubation experiments with SME. Finally, SRIH secretion was significantly reduced by leptin (down by 35% vs. control from 0 to 30 min of treatment) in cultured SME. These data show that leptin is effective in stimulating GH secretion by acting at two different levels: (1) it stimulates GH secretion directly from pituitary slices, and (2) it reduces SRIH tone from the median eminence and, indirectly, increases GH secretion from the pituitary. These results support the hypothesis that leptin may be an interesting hormonal mediator of growth and related metabolic effects by acting directly on the hypothalamic-pituitary axis.

Importance of premeal injection time in insulin therapy: Humalog Mix25 is convenient for improved post-prandial glycemic control in type 2 diabetic patients with Italian dietary habits

Abstract.We investigated the use, in a short period, of Humalog Mix25 (Mix25) in a twice-daily administration regimen compared to a twice-daily injection therapy with Humulin 30/70 (30/70) in diabetic patients with Italian dietary habits. We studied 33 type 2 diabetic patients aged 59.1±8.1 years, BMI 29.8±2.7 kg/m2, duration of diabetes and insulin therapy of 14.4±9.8 and 4.2±4.6 years, respectively. After a 4-day leadin period of twice-daily human insulin 30/70 treatment, patients were randomized to one of two treatment sequences: (1) a twice-daily regimen with Mix25 just 5 minutes before the morning and evening meals for 12 days, followed by a twicedaily therapy with human insulin 30/70 given 30 minutes before the morning and evening meals for an additional 12 days; or (2) the alternate sequence. Each patient underwent a mixed meal test: Humulin 30/70 was administered 30 minutes before the meal, while Mix25 was given 5 minutes before. The 2-hour post-prandial glucose concentration after breakfast was significantly lower during treatment with Mix25 than with Humulin 30/70 (157±43.2 vs. 180±43.2 mg/dl, p<0.05). The glycemic excursion after dinner on Mix25 treatment was significantly lower than with Humulin 30/70 (12.2±48.01 vs. 35.5±36.92 mg/dl, p<0.05). AUCglucose after Mix25 was lower than after Humulin 30/70. Glycemia after test meal was significantly lower with Mix25 than with Humulin 30/70. Insulin and free insulin concentrations after the test meal were significantly higher with Mix25 in comparison to Humulin 30/70. AUC serum insulin and free insulin curves after Mix25 were significantly higher than after Humulin 30/70 (p=0.028 and p=0.005, respectively). Twice-daily injections of Humalog Mix25, compared to human insulin 30/70 in type 2 diabetic patients with Italian dietary habits, provide improved and lasting post-prandial glycemic control, with the great convenience of the injection just before the meal.

The effect of treatment with growth hormone on fertility outcome in eugonadal women with growth hormone deficiency: report of four cases and review of the literature.

OBJECTIVE To highlight the clinical role of standard GH replacement treatment on fertility and pregnancy outcomes in four infertile eugonadal women with GH deficiency (GHD). DESIGN Case report. SETTING Department of endocrinology and infertility clinic, tertiary-care university hospital. PATIENT(S) Four normogonadotrophic, normoprolactinemic patients with long-standing infertility, affected by GHD. In two patients (aged 30 and 34 years) GHD was diagnosed after a brain injury. The third patient (age 30 years) had a primary empty sella, documented by magnetic resonance imaging of the pituitary. The last patient (age 28 years) underwent transsphenoidal surgery for Ratkes cyst. The LH and FSH responses to GnRH were normal in all four patients. Two of the four patients also had secondary hypoadrenalism and hypothyroidism. INTERVENTION(S) Patients received recombinant human GH replacement therapy (0.9-1.8 mg/week) for 6-12 months until pregnancy was first indicated by biochemical markers (beta-hCG) and later confirmed by transvaginal sonography. The GH therapy was discontinued after confirmation of pregnancy. MAIN OUTCOME MEASURE(S) Pregnancy. RESULT(S) All patients remained off treatment throughout pregnancy; they had uneventful pregnancies and term deliveries. The babies were healthy and normal in terms of length and weight. CONCLUSION(S) Our case studies confirm the important clinical role of the GH-insulin-like growth factor I system in oocyte fertilization and the beginning of pregnancy in a selected population of eugonadotrophic infertile women.

Predictors of pituitary dysfunction in patients surviving ischemic stroke.

BACKGROUND Stroke is a leading cause of death in industrialized countries, representing the main cause of long-term disability. Recent studies indicate that hypopituitarism may be observed after an acute stroke. OBJECTIVE The aim was to prospectively investigate incidence and pattern of pituitary dysfunction in patients suffering ischemic stroke and to assess the predictive value of different clinical and radiological parameters for hypopituitarism. PATIENTS AND METHODS We assessed endocrine, clinical, radiological, and functional parameters in 56 patients (34 males; mean age, 64.8 ± 1.3 yr; mean body mass index, 25.8 ± 0.45 kg/m(2)) at 1-3 months (visit 1) and 12-15 months (visit 2) after an ischemic stroke. RESULTS At visit 1, hypopituitarism was detected in 20 (35.7%) of 56 stroke patients, with multiple deficits in three and isolated deficits in 17. At visit 2, hypopituitarism was detected in 18 (37.5%) of 48 stroke patients, with multiple deficits in two. Four patients with previously diagnosed isolated GH or LH/FSH deficit exhibited normal pituitary function, whereas GH deficiency was newly diagnosed in three cases. Hypopituitarism was associated with worse outcome. We identified both clinical (preexisting diabetes mellitus, medical complications during hospitalization) and radiological (Alberta Stroke Programme Early CT Score ≤ 7) parameters as major risk factors for developing hypopituitarism after ischemic stroke. CONCLUSIONS Hypopituitarism may associate with ischemic stroke in one third of cases and persist in a long-term period, aggravating the functional outcome. We identified specific risk factors for hypopituitarism after stroke, which may help to select patients needing an accurate endocrine evaluation to improve stroke outcome.

Protein C and protein S changes in GH-deficient adults on r-HGH replacement therapy: Correlations with PAI-1 and t-PA plasma levels☆☆☆

BACKGROUND In the rat liver, growth hormone (GH) affects the synthesis of vitamin-K-dependent factors, including Protein C (prot.C) and protein S (prot.S), two natural anticoagulants that prevent hypercoagulable states. Adults with GH deficiency (GHD) are at risk of thrombotic events. High circulating levels of PAI-1 and t-PA, that reflect hypercoagulable states, may contribute to such risk. In GHD adults on replacement therapy with recombinant human GH (r-HGH), %Δ PAI-1 and %Δ t-PA are related to %Δ insulin changes. OBJECTIVES To evaluate changes in vitamin-K-dependent factors in GHD on r-HGH replacement. METHODS In 60 GHD adults, to relate plasma levels of vitamin-K-dependent factors with those of PAI-1, t-PA and insulin before and after 6-month (6-mo) replacement therapy with r-HGH. RESULTS After 6-mo r-HGH replacement, %Δ insulin enhancements occurred in 36/60 subjects. PAI-1, t-PA, Prot.C, Prot.S and FVIIact did not change in them. In the 24/40 subjects that experienced %Δ insulin reductions, Prot.C (p=0.025), Prot.S (p=0.031) and FVIIact (p=0.049) decreased significantly. PAI-1 (p=0.019) and t-PA antigen (p=0.009) behaved similarly. In a multivariate analysis, %∆ PAI-1 (β=0.436, p<0.01) was the strongest predictor of %∆ prot.S, wheras %∆ t-PA (β=0.385, p<0.008) and %∆ insulin (β=0.429, p<0.004) were the strongest predictors of %∆ prot.C. In all cases, regardless of %Δ insulin changes, FII, FVII Ag and FIX levels did not change from baseline. CONCLUSIONS In GHD adults on r-HGH replacement, changes in vitamin-K-dependent factors reflect a subtle adaptation of the natural anticoagulant system to PAI-1 and t-PA changes, via the response of insulin to r-HGH.

Evaluation of pre- and postprandial growth hormone (GH)-releasing hormone-induced GH response in subjects with persistent body weight normalisation after biliopancreatic diversion

BACKGROUND: Obesity is characterised by growth hormone (GH) abnormalities, including a blunted response to stimulation and a ‘paradoxical’ increase after meals. The blunted GH release is reversed by a surgical intestinal bypass procedure. However, this does not mean that normal GH dynamics have been restored. The present study assessed whether post-surgical weight reduction in obese patients normalised the modulation of GH release produced by metabolic fuels.SUBJECTS: Ten obese female subjects, aged 23–54 y, were studied before and after biliopancreatic diversion (BPD). All patients, after surgery, had experienced a significant reduction in body weight (mean body mass index (BMI) 25.78±1.01 kg/m2 vs 44.68±1.73 kg/m2). Two groups were also studied as controls: Ten normal body weight female subjects and ten patients suffering from anorexia nervosa (AN, mean BMI 17.46±1.12 kg/m2).MEASUREMENTS: We have studied the GH response to a GH releasing hormone (GHRH) bolus (1 μg/kg iv, at 13.00 h) before and after a standard meal.RESULTS: In post-BPD subjects, the GH response to GHRH in the fasting state, was clearly augmented in comparison with the pre-BPD values (peak values 18.06±4.56 vs 3.24±0.68 μg/L). In post-BPD subjects the postprandial GH response was further augmented in comparison with the fasting test (peak 30.12±4.99 μg/L, P<0.05). This pattern was similar to that observed in anorexic patients.CONCLUSION: The surgical procedure restores a normal GH response to GHRH in the fasting state, but the ‘paradoxical’ GH response after meals remains present, suggesting a persistent GH derangement in such patients, which is not related to body weight per se. The surgical procedure makes obese patients similar to anorexics, in the relationships between metabolic fuels and GH secretion. The persistence of the GH postprandial response to GHRH in post-BPD subjects suggests a role for metabolic fuels in the regulation of somatostatin (SRIF) secretion.

Lack of change in insulin levels as a biological marker of PAI-1 lowering in GH-deficient adults on r-HGH replacement therapy.

Patients with growth hormone (GH) deficiency (GHD) have decreased life expectancy and increased risk of cardiovascular events [3,22,25]. An impaired fibrinolysis is a major determinant of cardiovascular risk [4,27]. PAI-1, the main physiologic inhibitor of tPA, regulates the fibrinolytic system. Raised plasma levels of PAI-1 have been documented in ischemic heart disease and in subjects who subsequently develop myocardial infarction [7]. Abnormally high circulating levels of PAI-1 are associated with high risk for stroke and myocardial ischemia [4,27]. Prospectively, raised levels of PAI-1 is a strong determinant of vascular ischemic events [11,18,20,21]. It is also known [see 16,17 for a review], that PAI-1 inhibition rises with the increase in t-PA antigen, so that high levels of either factor reflect an impaired fibrinolysis. This information is based on a series of data: a) concentrations of t-PA antigen above normal ranges are present in subjects with high plasma PAI-1 levels; b) increases in t-PA antigen reflect the inhibitory effect of PAI-1 on t-PA

Changes in insulin levels following 6-month treatment with recombinant human growth hormone in growth hormone-deficient adults

Introduction: Eighty-six adult patients with GH deficiency (GHD) of adult or childhood onset were treated for 6 months, with recombinant human growth hormone (r-hGH) at a low (LD) or conventional dose (CD). The treatment effect on insulin levels was investigated. Methods: This manuscript refers to the Italian addendum to an International Study (B9R-EW-GDED) in which patients with GHD were randomized to receive r-hGH replacement therapy at a dose of either 3 μg/kg/day or 6 μg/kg/day for the 3 months. The dose was then doubled for the next 3 months. Results: After 6 months of r-hGH treatment, insulin levels increased with both GH dosages, with a greater increase achieved in the low-dose subgroup. Insulin levels also increased significantly in the childhood-onset, while even decreased in the adult-onset subgroup. On the whole, in more than 50% of patients, insulin values rose by >13%. Moreover, mean levels of IGF-I increased 2–3 fold (p<0.001 vs baseline) in both the LD and CD groups. Significant and similar increases in IGF binding protein-3 levels were seen in both the LD and CD groups over the treatment period, regardless the time of onset of GHD. Conclusion: Insulin increased with both GH dosages and more than half of patients presented an important increase in insulin plasma levels. It would be of interest to assess if there is a correlation between the changes in insulin levels and other cardiovascular risk factors such as hemostatic parameters.

Prediction of response to growth hormone treatment in pre-pubertal children with growth hormone deficiency

Background: GH therapy response varies substantially among patients. Several models were developed to predict the efficacy of GH therapy in children. Aim: To evaluate the accuracy of a growth prediction model using data from an Italian pediatric GH deficiency (GHD) cohort (GeNeSIS, Growth Prediction Sub-study). Methods: Open-label, multicenter study in 22 Italian pre-pubertal GH treatment-naïve patients with GHD (8 female, 14 male, 0.5 to 12.2 yr), 18 isolated GHD, 4 multiple pituitary hormone deficiency given recombinat human GH therapy (0.025–0.035 mg/kg/day) for 12 months. Growth prediction was performed, after 3 months of treatment, using baseline data [bone age (BA) and IGF-I], a urinary marker of bone turnover [deoxypyridinoline crosslinks (DPD)] at 4 weeks, and height velocity (HV) at 3 months. Results were expressed as 1st-yr HV using the following equation: 1-yr HV (cm) = 3.543 − (2.337 × BA) − (0.010 × IGF-I) + (0.100 × DPD) + (0.299 × 3-month HV). Predictions were compared to the 1st-yr HV and accuracy was calculated as percentage of the difference between mean calculated HV and the real 1st-yr HV. Results: For females predicted HV was 12.98±4.82 cm/yr and actually was 13.05±3.91 cm/yr after the 1st year; for males predicted HV was 13.95±5.39 cm/yr and actually was 12.93±5.02 cm/yr. Conclusions: In this paediatric Italian cohort with GHD, a growth prediction model seems to be a valid tool to assess 1st-yr response to GH treatment in Italian children.

Bone mineral density in pre-climateric obese women pre- and post biliopancreatic diversion (BPD)

Study Methods: There was a selected group of women in premenopausal period (N=19), aging 39.Oe8.0 suffering from differentiated thyroid gland carcinoma. To all of them, the total thyroidectomy was done and the thyroxine suppression therapy was introduced. The duration of the suppression therapy from the beginning of the research amounted to 9.4e6.4 years. Laboratory results have excluded other possible factors for secondary osteoporiosis. The prospective study of the bone densiometry was done to all of the examinees using the method of dual photon x-ray absorptiometry (DXA) of the spine and the femoral neck, and also by the method of single-photon absorptiometry (SPA) of the distal radius. Results: In the beginning of this study, while the patients were treated for 10 years osteopeny was found in the spine and the femoral neck in two examinees for every region. On the distal radius osteopeny was found in 4 examinees. The total was 8 out of 19 with statistically significant loss o f bone mass was in any region of skeleton. However, looking at the individual scores, osteopeny was found in 6 examinees on the distal radius but on the spine and the femoral neck, there was bone loss in several women but not to the point that would create osteopeny. But, after the 4 years of measurement, t-test had shown some significant loss of bone mass on the distal radius. The period of one year is not enough to record significant bone loss. Conclusions: We can come to the decision that women who begin with a long-term thyroxine therapy (about 10 years) in premenopausal period can develop osteopeny in the beginning of menopause. In that case, those women should complete a mammography test and bone densitometry before hormone replacement therapy is used.