Recombinant growth hormone (GH) therapy in GH-deficient adults: a long-term controlled study on daily versus thrice weekly injections

Currently, replacement recombinant GH (rGH) therapy in GH-deficient (GHD) adults is performed in daily injections. This modality of treatment is not complied with by the totality of GHD patients, who are supposed to receive life-long replacement. The aim of our study was to compare daily vs. thrice weekly (TIW) rGH injection effects on lipid profile, body composition, bone metabolism, and bone density in 34 GHD patients (13 women and 21 men; median age, 39 yr; range, 30-55 yr) randomly assigned to different therapeutic regimens. Group A included 18 patients receiving daily rGH injections, and group B included 16 patients receiving TIW injections of rGH. The starting dose of rGH was 10 microg/kg x day in both groups. Subsequently, the dose was adjusted to maintain serum insulin-like growth factor I (IGF-I) concentrations in the normal age-adjusted range. IGF-I levels were assessed before and after 1, 3, 6, and 12 months of rGH treatment, and lipid profile, body composition, bone metabolism, and bone density were evaluated before and after 6 and 12 months of treatment. Thirty-four healthy subjects served as controls. In the basal condition, lipid profile, body composition, bone metabolism, and bone density were significantly different in patients compared to controls. Conversely, patients included in groups A and B had similar serum IGF-I levels, lipid profile, body composition, bone metabolism, and bone density. After 3 months of rGH treatment, IGF-I levels were normalized in 15 of 18 patients (83.3%) in group A and in 7 of 16 patients (43.7%) in group B (chi2 = 4.21; P = 0.04). At this time point, serum IGF-I levels in patients in group A (202+/-57.5 microg/L) were significantly higher than those in patients in group B (155+/-45.1 microg/L; P = 0.001). After 6 months of therapy, serum IGF-I levels were normalized in all patients and were similar in both groups (223+/-35.2 vs. 212+/-41.4 microg/L, A vs. B, respectively). IGF-I levels remained normal until the 12-month follow-up. After 6 months of rGH replacement, total cholesterol, low density lipoprotein cholesterol, triglycerides, bioelectrical impedance, and body fat mass were significantly reduced, whereas high density lipoprotein cholesterol levels and lean body mass were significantly increased in both groups of patients, without any difference between them. No further change in lipid profile and body composition was observed after 12 months of treatment. Serum bone GLA protein and procollagen III levels were significantly increased after 6 months, and a downward trend was observed after 12 months of rGH replacement. However, a slight, but significant, increase in bone mineral density was observed in both groups only after 12 months (P = 0.0001). All patients in group B had good compliance to the TIW treatment, whereas 5 patients in group A had poor compliance to the treatment (chi2 = 3.2; P = 0.07). In conclusion, our randomized, prospective, and controlled study confirmed that rGH therapy with TIW injection regimen is effective in normalizing IGF-I levels and improving lipid profile, body composition, bone metabolism, and bone density. It also demonstrated that this efficacy is comparable to that observed in patients treated with daily rhGH therapy, with few side-effects and good compliance.

Long-term treatment with interferon-beta therapy for multiple sclerosis and occurrence of Graves' disease

Interferon (IFN)-beta has become a widespread therapy for multiple sclerosis. As already reported for IFN-alpha, thyroid autoimmunity and dysfunctions have been observed also in course of IFN-beta therapy. Nevertheless, very few cases of Graves' disease, occurred in such condition, have been reported in literature. We here describe the case of a 40-year-old female affected by multiple sclerosis, who received IFN-beta-1b, 8 million IU s.c. every other day for her condition. After 22 months of cytokine administration, she developed a severe Graves' disease with persistently positive TR-Ab which suggested the withdrawal of the treatment. Our patient had performed a complete thyroid evaluation with normal findings, before and during the first 6 months of therapy. This case suggests that patients undergoing long-term IFN-beta therapy should be monitored for thyroid hormones and antibodies throughout the treatment as thyroidal side effect can be a late event.

Multicenter study on TGPO autoantibody prevalence in various thyroid and non-thyroid diseases; relationships with thyroglobulin and thyroperoxidase autoantibody parameters

OBJECTIVE

TGPO autoantibodies (aAbs) that bind simultaneously to thyroglobulin (Tg) and thyroperoxidase (TPO) are present in the serum of patients with autoimmune thyroid diseases (AITD) and have been found to differ from monospecific Tg and TPO aAbs. To obtain further insights on the prevalence defined as the rate of occurrence and significance of TGPO aAbs in a large population, we carried out a collaborative study involving 15 European teams.

METHODS

Serum samples from 3122 patients with various thyroid and non-thyroid diseases and normal subjects were assayed using a novel TGPO aAb detection kit. This test was designed so that TGPO aAbs are trapped between the Tg-coated solid phase and the soluble TPO labeled with a radioiodinated monoclonal antibody.

RESULTS

Only three out of the 220 normal subjects (prevalence of 1.4%) were found to have positive TGPO aAb levels, which were mainly observed in the patients with AITD: the group of patients suffering from Hashimoto's thyroiditis had a TGPO aAb prevalence of 40.5% (n=437 patients), those with Graves' disease, a prevalence of 34.6% (n=645) and those with post-partum thyroiditis, 16.0% (n=243). Among the non-AITD patients with positive TGPO aAb levels, the TGPO aAb prevalence ranged from 20.7% among those with thyroid cancer (n=246) to 0% among those with toxic thyroid nodules (n=47). Among the patients with non-thyroid diseases, the TGPO aAb prevalence ranged from 9.8% in the case of Biermer's pernicious anemia (n=78) to 0% in that of premature ovarian failure (n=44). It is worth noting that the groups showing the highest TGPO aAb prevalence also contained the patients with the highest TGPO aAb titers. Statistical comparisons between the TGPO aAb prevalences in the various groups showed that TGPO aAb could be used as a parameter to distinguish between the groups of Hashimoto's and Graves' patients and between the women with post-partum thyroiditis and the post-partum women with only Tg and/or TPO aAb established during early pregnancy. Unexpectedly, the correlations between TGPO aAbs and Tg and TPO aAbs were found to depend mainly on the assay kit used.

CONCLUSION

High TGPO aAb titers are consistently associated with AITD but the reverse was not found to be true. TGPO aAbs are a potentially useful tool, however, for establishing Hashimoto's diagnosis, and would be worth testing in this respect with a view to using them for routine AITD investigations.

Low plasma insulin-like growth factor-1 concentrations predict worsening of insulin-mediated glucose uptake in older people

OBJECTIVE

The relationship among insulin action, advancing age, and insulin like growth factor-1 (IGF-1) is poorly understood. To gain further insight, the predictive role that low plasma IGF-1 concentration may have on insulin- mediated glucose uptake in older persons was investigated.

DESIGN

The study was designed as a longitudinal, observational trial.

PARTICIPANTS

Fifty-eight healthy aged (73.1+/-9.4 years) subjects (31 males/27 females) were followed up for 12 months.

MEASUREMENTS

At baseline and at the end of the follow-up, insulin-mediated glucose uptake was assessed by euglycemic glucose clamp and plasma total IGF-1 and IGF-binding protein 3 (IGF-BP-3) in each subject, and concentrations were determined.

RESULTS

At baseline, plasma IGF-1 concentrations correlated with whole body glucose uptake (WBGD) (r = 0.39, P < .003), insulin-stimulated glucose oxidation (GOX) (r = 0.35, P < .009), and non-oxidative glucose metabolism (r = 0.37, P < .007). Such correlations were also independent of age, sex, body fat, and waist/hip ratio. Fasting plasma total IGF-1 concentrations (84+/-56 vs 63+/-44 microg/L, P < .040), plasma IGF-1/IGF-BP3 molar ratio (0.13+/-0.05 vs 0.10+/-0.03 P < .050), and WBGD (34.8+/-5.0 vs 23.1+/-4.6 micromol/kg x min, P < .010) were more elevated at baseline than at the end of the follow-up. Low baseline fasting plasma IGF-1 concentration (RR = 1.5, 95%CI = 1.3-1.7) and plasma IGF-1/IGFBP-3 molar ratio (RR = 1.4, 95% CI = 1.3-1.8) predicted a decline in WBGD. The predictive role of plasma IGF-1 on age-related decline in WBGD was independent of age, sex, body fat, waist/hip ratio, and degree of physical activity (model 1), or of fasting plasma free fatty acid and triglyceride concentrations, LDL/HDL ratio, and basal adjusted respiratory quotient (model 2). Finally, low plasma IGF-1 concentration predicts a decline in WBGD independent of body fat, free fatty acids, waist/hip ratio, and basal adjusted respiratory quotient (model 3).

CONCLUSION

Our study demonstrates that fasting plasma IGF-1 concentration may have a modulatory role on insulin action in older people. This finding might prompt an evaluation of the direct effect of IGF-1 administration on insulin sensitivity in older adults.

Plasma leptin level is associated with myocardial wall thickness in hypertensive insulin-resistant men

Leptin, the product of the ob gene, has been shown to increase heart rate and blood pressure through a stimulation of cardiac sympathetic nervous system activity, a phenomenon also involved in the pathogenesis of left ventricular hypertrophy in hypertensives. Thus, we hypothesize that plasma leptin concentration is associated with left ventricular hypertrophy. Forty hypertensive males and 15 healthy male subjects underwent anthropometric and echocardiographic evaluations, assessment of insulin sensitivity through euglycemic glucose clamp combined with indirect calorimetry, and determination of fasting plasma leptin concentration. Fasting plasma leptin levels were higher in hypertensives than in controls (6.48+/-2.9 versus 4. 62+/-1.5 ng/mL, P<0.05); these results were unchanged after adjustment for body mass index (P<0.05). In the whole group of patients (n=55), fasting plasma leptin concentration was correlated with body mass index (r=0.46, P<0.001) and waist/hip ratio (r=0.50, P<0.001); independent of body mass index and waist/hip ratio, fasting plasma leptin concentration was correlated (n=55) with whole-body glucose disposal (r=-0.27, P<0.04), interventricular septum thickness (r=0.34, P<0.001), posterior wall thickness (r=0.38, P<0.003), and the sum of wall thicknesses (r=0.68, P<0.001). In a multivariate analysis (n=55), age, body mass index, fasting plasma leptin concentration, plasma Na(+) concentration, whole-body glucose disposal, and diastolic blood pressure explained 68% of the variability of the sum of wall thicknesses with fasting plasma leptin concentration (P<0.03), whole body glucose disposal (P<0.002), and diastolic blood pressure (P<0.001), which were significantly and independently associated with the sum of wall thicknesses. In conclusion, our study demonstrates that fasting plasma leptin levels are associated with increased myocardial wall thickness independent of body composition and blood pressure levels in hypertensives.

Successful outcome of pregnancy in a thyroidectomized-parathyroidectomized young woman affected by severe hypothyroidism

Severe hypothyroidism was discovered in a young woman in her 29th week of pregnancy. Previously, at the age of 12 years, she had undergone thyroid surgery for Graves' disease that resulted in persistent hypothyroidism and hypoparathyroidism. After surgical excision, the patient started levothyroxine replacement therapy and had regular control of thyroid function with normal findings throughout the years. The dose of levothyroxine had not been adjusted when the pregnancy started, and at the 29th week of gestation the patient had a thyrotropin (TSH) of 72.4 microU/mL. Ultrasound studies were performed in order to monitor fetal development. The fetal parameters analyzed before the adjustment of levothyroxine therapy showed growth retardation of various degrees. All analyzed fetal parameters (biparietal diameter, cranial and abdominal circumference, humerus and femur length) improved during the last 6 weeks of gestation, showing a good correlation with the newly achieved euthyroid state of the mother. The infant was clinically euthyroid at birth and was found normal at all evaluations of the neonatal hypothyroidism screening program (1, 5, 30 days).

Diabetes insipidus and increased serum levels of leptin and lactate-dehydrogenase (LDH) in an adolescent boy with a primary intracranial germinoma. Case report and an endocrinological revaluation of literature

A 16-year-old boy presented with a four-month history of polyuria-polydipsia and a diplopia which had reverted after treatment. The neuroimaging studies performed had been strongly suggestive of an optic nerve glioma, while endocrinological investigation (beta-hCG 420 IU/L) has lead to the correct diagnosis later confirmed at the immunohystochemical analysis performed at biopsy. The high serum level of hCG was unaffected by bromocriptine nor octreotide, while the PRL level (80.0 microg/L) was reduced only by bromocriptine. Among the several tumor markers which may be secreted by such lesions, ours is the first reported case of an elevation of serum LDH for a primary intracranial germinoma. Moreover, the elevated value of serum leptin reported by us might be due to the insensitivity of the hypothalamic structures to endogenous leptin.

Left ventricular diastolic dysfunction in patients with subclinical hypothyroidism

Although subclinical hypothyroidism is frequently diagnosed, the decision to institute a substitutive therapy with L-T4 remains controversial. Because the cardiovascular system is considered a main target for the action of thyroid hormone, we investigated whether subclinical hypothyroidism induces cardiovascular abnormalities. Twenty-six patients (mean age, 36 +/- 12 yr) were evaluated by Doppler-echocardiography, whereas a subgroup of 10 patients, randomly selected, were reevaluated after 6 months of L-T4 substitutive therapy (mean dose, 68 microg daily). Thirty subjects (matched for age, sex, and body surface area) served as controls. Mean plasma TSH was significantly higher in patients (P < 0.001), whereas mean serum free T4 and free T3 concentrations, although in the normal range, were significantly lower (P < 0.001 and P < 0.005, respectively). Blood pressure and heart rate did not differ from control values. Echocardiogram examination showed no abnormalities of the left ventricular morphology and a slight, but not significant, reduction in the systolic function in the patient group. In contrast, Doppler-derived indices of diastolic function showed significant prolongation of the isovolumic relaxation time (94 +/- 13 vs. 84 +/- 8 msec; P < 0.001), increased A wave (55 +/- 13 vs. 48 +/- 9 cm/sec; P < 0.05), and reduced early diastolic mitral flow velocity/late diastolic mitral flow velocity ratio (1.4 +/- 0.3 vs. 1.7 +/- 0.3; P < 0.001). In the subgroup of 10 patients, thyroid hormone profile was normalized by 6 months of L-T4 substitutive therapy, whereas no changes were observed in the left ventricular morphology. Systolic function was significantly enhanced, as compared with pretreatment values (P < 0.01) but did not differ from control values. Also, systemic vascular resistance was significantly decreased by L-T4 replacement therapy. Assessment of diastolic function showed significant shortening of isovolumic relaxation time (77 +/- 15 vs. 91 +/- 8; P < 0.05), reduction of A wave (51 +/- 13 vs. 60 +/- 12; P < 0.01), and increase of early diastolic mitral flow velocity/late diastolic mitral flow velocity ratio (1.7 +/- 0.4 vs. 1.3 +/- 0.3; P < 0.001). These indices, however, were comparable with those of control subjects. These findings indicate that subclinical hypothyroidism affects diastolic function and that this abnormality may be reversed by L-T4 substitutive therapy.

Lack of association between changes in plasma leptin concentration and in food intake during the menstrual cycle

BACKGROUND

Changes in plasma leptin concentration and food intake occur during the menstrual cycle; because leptin regulates food intake, one could hypothesize that changes in plasma leptin concentration and in food intake are associated throughout the menstrual cycle. However, no data have ever been provided to support such a relationship. The aim of our study was to investigate, during the different phases of the menstrual cycle, (a) the changes in plasma leptin concentration and, if such changes were demonstrated, (b) the potential relationship between the changes in plasma leptin concentration and food intake.

DESIGN

The study was designed as an observational study. The plasma leptin concentration was determined in 16 healthy, young women during different phases of the menstrual cycle. At the same time, the basal metabolic rate (BMR), respiratory quotient (RQ) and food intake (FI) were also determined.

RESULTS

The plasma leptin concentration increased throughout the menstrual cycle (P < 0.01 for trend) and was significantly correlated with plasma progesterone concentration (r = 0.55, P < 0.007, for follicular phase, r = 0.58, P < 0.02, for the periovulatory period and r = 0.57, P < 0.02, for the luteal phase). No significant differences in BMR and fasting RQ throughout the different phases of the menstrual cycle were found. In contrast, FI significantly declined in the periovulatory phase. No significant correlations between BMR, RQ and FI values and fasting plasma leptin concentration at all menstrual phases were found.

CONCLUSION

Changes in plasma leptin concentration and in food intake were found at different phases of the menstrual cycle. Nevertheless, no correlation among those parameters at any phase of the menstrual cycle was observed.

Tissue inhibitor of metalloprotease (TIMP)-1 and proliferative behaviour of clonal breast cancer cells

In the present paper, we have examined whether human tissue inhibitor of metalloprotease-1 (hTIMP-1) is able to exert a growth factor-like effect on two clonal cell lines (BC-3A and BC-61), isolated from a parental line of human breast carcinoma cells (8701-BC), and endowed with different growth and invasive behaviour 'in vitro' and in nude mouse. The data obtained indicate that only the more tumorigenic clonal cell line (BC-61) is responsive to hTIMP-1 treatment by increasing its proliferative rate in a dose-dependent manner. It was also found that BC-61 cells selectively express a transmembrane protein of about 80 kDa able to bind hTIMP-1 'in vitro' and 'in vivo' with high affinity (Kd of 0.07 +/- 0.004 nM), and that treatment of BC-61 cells with a proliferation-promoting concentration of hTIMP-1 is able to stimulate tyrosine-targeted phosphorylation. The cumulative results obtained strongly support the hypothesis that hTIMP-1, 'classically' regarded as a collagenase inhibitor, may be a crucial element of the extracellular signalling network during breast cancer development by controlling cell growth phenotype in autocrine and paracrine manner, and that intratumoural heterogeneity for the biological response to TIMP-1 may exist within the composite cell population of the primary tumour site.

Mean arterial blood pressure and serum levels of the molar ratio of insulin-like growth factor-1 to its binding protein-3 in healthy centenarians

OBJECTIVE

Healthy centenarians have a greater molar ratio of plasma insulin-like growth factor-1 to insulin-like growth factor binding protein-3 than that of aged subjects. We investigated the question of whether differences in mean arterial pressure and in this plasma ratio were related in healthy centenarians.

SUBJECTS AND METHODS

We studied 52 subjects in total, 30 aged subjects (70-99 years) and 22 healthy centenarians (> 100 years) to determine differences in mean arterial pressure, endothelial function and intracellular cation levels.

RESULTS

In the healthy centenarians, the molar ratio of fasting plasma insulin-like growth factor-1 to its binding protein-3 was significantly correlated with mean arterial pressure (r = -0.66, P < 0.001). Baseline (19.3 +/- 1.5 versus 27.6 +/- 2.2 mumol/l, P < 0.05) and L-arginine-stimulated percentage increases in the plasma total nitrate: nitrite ratio (67 +/- 3.4 versus 48 +/- 4.5%, P < 0.03) were greater in the healthy centenarians than in the aged subjects. An L-arginine bolus elicited an increase in forearm blood flow which was correlated with the percentage increase in the plasma total nitrate: nitrite ratio (r = 0.79, P < 0.001) and with the fasting erythrocyte magnesium concentration (r = 0.80, P < 0.001) in healthy centenarians. Both correlations remained significant (P < 0.01) after adjustment for sex, body mass index and the waist: hip ratio. Moreover, the fasting plasma molar ratio of insulin-like growth factor-1 to its binding protein-3 was correlated with the percentage increase in forearm blood flow (r = 0.59, P < 0.005) and with the percentage increase in the plasma total nitrate: nitrite ratio (r = 0.54, P < 0.009) in healthy centenarians. The centenarians had higher baseline total erythrocyte magnesium and lower calcium concentrations than the aged subjects. The addition of insulin growth factor-1 to the incubation medium increased the total intracellular erythrocyte magnesium content and decreased the calcium content in both groups of subjects. Nevertheless, the percentage increase in total erythrocyte magnesium (33 +/- 3.8 versus 12 +/- 3.4%, P < 0.03) and decline in intracellular calcium (17 +/- 2.8 versus 8 +/- 3.1%, P < 0.02) concentrations were greater in the healthy centenarians than the aged subjects.

CONCLUSION

In healthy centenarians, insulin-like growth factor-1 may preserve endothelial function and modulate the intracellular cation content, thus contributing to a lower mean arterial pressure than that in aged subjects.

Occurrence of thyroid autoimmunity and dysfunction throughout a nine-month follow-up in patients undergoing interferon-beta therapy for multiple sclerosis

Thyroid autoimmunity and dysfunction are a well known side effect of IFN alpha therapy for viral hepatitis and tumors, while the IFN beta effects on the thyroid gland in neurological patients have not been studied. The aim of this longitudinal study was to look for the appearance of thyroid autoimmunity as well as for the occurrence of overt thyroid disease in the patients affected by multiple sclerosis (MS) treated with IFN beta 1b. Eight patients (4 males, 4 females) undergoing r-IFN beta 1b treatment (8 M.U. every other day for 9 months) for relapsing remitting multiple sclerosis entered the study. We have analyzed thyroid function parameters and auto antibody levels before and after 1, 2, 3, 6 and 9 months of therapy. None of them referred to familiar thyroid pathology or presented clinically overt thyroid disease except for one patient (case 4) who showed TPO-Ab pretreatment positivity and another (case 8) who was in therapy with Levothyroxine 100 microg/die for multinodular goiter. The number of patients with appearance of thyroid antibodies has slowly increased, until the third month of therapy with 3 patients out of 7 positive for TPO-Ab. The only case of overt thyroid dysfunction reported by us appeared after nine months of therapy and consisted of a hypothyroidism. Our data suggest that short-term interferon beta treatment is able to induce thyroid autoimmunity (42.8%) and dysfunction (12.5%).

Advancing age and insulin resistance: role of plasma tumor necrosis factor-alpha

In 70 healthy subjects with a large age range, the relationships between plasma tumor necrosis factor-alpha (TNF-alpha) and body composition, insulin action, and substrate oxidation were investigated. In the cross-sectional study (n = 70), advancing age correlated with plasma TNF-alpha concentration (r = 0.64, P < 0.001) and whole body glucose disposal (WBGD; r= -0.38, P < 0.01). The correlation between plasma TNF-alpha and age was independent of sex and body fat (BF; r = 0.31, P < 0.01). Independent of age and sex, a significant relationship between plasma TNF-alpha and leptin concentration (r = 0.29, P < 0.02) was also found. After control for age, sex, BF, and waist-to-hip ratio (WHR), plasma TNF-alpha was still correlated with WBGD (r = -0.33, P < 0.007). Further correction for plasma free fatty acid (FFA) concentration made the latter correlation no more significant. In a multivariate analysis, a model made by age, sex, BF, fat- free mass, WHR, and plasma TNF-alpha concentrations explained 69% of WBGD variability with age (P < 0.009), BF (P < 0.006), fat-free mass (P < 0.005), and plasma TNF-alpha (P < 0.05) significantly and independently associated with WBGD. In the longitudinal study, made with subjects at the highest tertiles of plasma TNF-alpha concentration (n = 50), plasma TNF-alpha concentration predicted a decline in WBGD independent of age, sex, BF, WHR [relative risk (RR) = 2.0; 95% confidence intervals (CI) = 1.2-2.4]. After further adjustment for plasma fasting FFA concentration, the predictive role of fasting plasma TNF-alpha concentration on WBGD (RR = 1.2; CI = 0.8-1.5) was no more significant. In conclusion, our study demonstrates that plasma TNF-alpha concentration is significantly associated with advancing age and that it predicts the impairment in insulin action with advancing age.

An improved polymerase chain reaction (PCR) protocol for unambigous detection of growth hormone gene deletions

hGH-1 gene deletions are detected by simultaneous PCR amplification along the two homologous DNA sequences flanking the hGH-1 gene on both sides and are differentiated by SmaI restriction enzyme digestion. We have observed that among the SmaI digested PCR products from normal homozygous subjects, from those heterozygous for the 7.6 kb deletion and from those heterozygous for a 6.7 kb deletion, along with the expected fragments there is an unexpected 1470 bp fragment. This fragment arises from the co-amplification of a third homologous sequence located downstream from the hGH-1 gene and it confuses differentiation between normal homozygous and heterozygous for 7.6 kb subjects from the 6.7 kb heterozygous subjects. To overcome this problem we have improved PCR conditions using a different reverse primer. These changes avoid the interaction of the primers with the third homologous sequence located downstream from the hGH-1 gene and prevent the appearance of this additional band that complicates the interpretation of the results. We conclude that the new reverse primer sequence avoids the amplification of the downstream hGH-1 gene sequence and the production of the 1474 bp band after SmaI endonuclease enzyme digestion and makes it possible to differentiate homozygous normal subjects and those who are heterozygous for a 7.6 kb deletion from those who are heterozygous for a 6.7 kb deletion.

Effect of metformin on food intake in obese subjects

BACKGROUND

It has been hypothesized that metformin inhibits food intake, but in humans such effect needs to be demonstrated. Our study aims at investigating the effect of metformin administration on food intake in obese, non-diabetic, normotensive patients.

METHODS

Thirty patients underwent a double-blind, randomized study. Placebo (P; n = 15) and metformin (M; n = 15) were both given for 15 days, and food intake (FI) was recorded at baseline and in the last 4 days of each treatment period.

RESULTS

M administration allowed a stronger decline in body weight (BW) (-2.8 +/- 1.6 vs. -0.3 +/- 0.4 kg P < 0.01), body fat (BF) (-1.4 +/- 1.2 vs. -0.3 +/- 1.1 kg P < 0.01), plasma leptin concentration (-5.2 +/- 8.9 vs. -1.8 +/- 10.4 ng mL-1 P < 0.05) and FI (-642 +/- 491 vs.-70 +/- 1165 kJ per 24 h P < 0.01) than P. In M-treated subjects, changes in FI significantly correlated with those in BW (r = 0.63, P < 0.007) and BF (r = 0.74, P < 0.001). Independently of sex and change in BF, the changes in FI and in fasting plasma leptin concentration (r = 0.58, P < 0.01) were still correlated.

CONCLUSION

Our study suggests that metformin administration is useful to inhibit FI and to lower BW and BF in obese non-diabetic patients.

Plasma sex hormones are significantly associated with plasma leptin concentration in healthy subjects

OBJECTIVE

In humans a sexual dimorphism of plasma leptin concentration has been demonstrated but its significance remains to be established. Sex hormones may have a role.

PATIENTS

Eighty healthy, non-obese subjects (41M/39F) were studied.

MEASUREMENTS

In the whole group of subjects plasma sex hormones, leptin and insulin concentrations were determined, body fat content assessed by bioimpedance analysis, body fat distribution evaluated and insulin-mediated glucose uptake measured by euglycemic hyperinsulinemic glucose.

RESULTS

After adjustment for age, gender, amount of body fat, waist/hip ratio (WHR) and fasting plasma insulin concentration, fasting plasma leptin was still significantly correlated with plasma DHEAS (r = -0.30, P < 0.006), oestradiol (r = 0.53, P < 0.001) and testosterone (r = -0.43, P < 0.001) in all subjects (n = 80). Independently of age, amount of body fat and WHR, fasting plasma leptin concentration correlated with plasma oestradiol (r = 0.38, P < 0.01) and total testosterone (r = -0.58, P < 0.001) in males (n = 41) and with fasting plasma oestradiol (r = 0.48, P < 0.002) in females (n = 39). To investigate the independent contribution of anthropometric and hormonal variables to fasting plasma leptin concentration, a multivariate stepwise regression analysis with fasting plasma leptin concentration as dependent variable was made. In the entire group (n = 80), the whole model explained 43% of fasting plasma leptin concentration with fasting plasma insulin, total testosterone and oestradiol concentrations significantly and independently associated with plasma leptin concentration. In this model, fasting plasma DHEAS, testosterone and oestradiol explained 25% of the variability in plasma leptin concentration.

CONCLUSION

Our study demonstrates that plasma sex hormone concentrations are associated with plasma leptin concentration.

Thyroid hormone plasmatic levels in rats treated with serotonin in acute and chronic way

Many experiments show that serotonin (5-HT) controls thyroidal function at hypothalamic level, inhibiting the TRH secretion. The majority of experiments are done in an acute way, consisting of a single serotonin dose injected intraperitoneally (i.p.) or intracerebroventricularly (ic) with the effect registered after a short time (usually 1 h) as in normal environmental conditions similar to the TSH stimulation test, that consists of transfer of the experimental animals from 30 degrees C to 4 degrees C for 30 min, thus inducing stimulation of the hypothalamus-hypophysis-thyroid axis. The aim of the present research was to study the correlation between 5-HT and the thyroidal function, measuring plasmatic thyroid hormone levels in rats i.p. treated in chronic (injected daily for 10 days with different doses of 5-HT), and in acute way (after 1 h from a single 2.0 mg/kg bw 5-HT dose) in normal environmental conditions to evidence the serotonin site action activity outside the blood-brain barrier. The results of the chronic experiment show an inhibitory effect of 5-HT, on T3 and T4 plasmatic level, only when it is injected at medium doses (0.2 and 0.4 mg/kg bw for T3, and 0.2 for T4), while the results of the acute experiment do not evidence any modification. These results show that in normal environmental conditions the outside 5-HT site action is active only when the 5-HT is injected chronically at defined doses, probably for a down-regulation phenomenon.

Insulin resistance and advancing age: what role for dehydroepiandrosterone sulfate?

The relationship between insulin resistance and aging is still debated. This study aims to investigate the role that age-related differences in plasma dehydroepiandrosterone sulfate (DHEAS) concentration may have on insulin action. For this reason, 75 subjects (42 men and 33 women) with a wide age range (21 to 106 years) were studied. In all subjects, plasma DHEAS and total testosterone concentrations were measured and a euglycemic clamp was used, but substrate oxidation was not determined in centenarians (n = 15). Plasma DHEAS correlated with age (r = -.77, P < .001) and whole-body glucose disposal (WBGD) (r = .57, P < .001). After controlling for age, sex, body fat, and waist to hip ratio (WHR), the association between plasma DHEAS and WBGD was still observed (r = .31, P < .005). Comparing subjects at the third tertile versus those at the first and second tertiles of plasma age-adjusted DHEAS concentration, the former group showed a weaker association between WBGD and age (r = -.38, P < .05) than the latter group (r = -.43, P < .002). The difference between the two regression lines was also significant (P < .03). After controlling for sex, body fat, and WHR, the association between plasma DHEAS and WBGD was dependent on the age of the subjects, being strong in adults (n = 30, age < 50 years, r = .69, P < .001), weak in old subjects (n = 30, age 51 to 99 years, r = .23, P < .05), and absent in centenarians (r = -.05, P < .88). With the subjects divided by sex throughout the different age groups, the univariate association between plasma DHEAS and WBGD was present in females (r = .43, P < .01) but not in males (r = .17, P < .32). Plasma total testosterone and insulin-like growth factor-1 (IGF-1) concentrations declined with advancing age and were significantly correlated with DHEAS and WBGD. In a multivariate analysis with WBGD as the dependent variable, a model including age, sex, body fat, WHR, DHEAS, total testosterone, and IGF-1 explained 66% of WBGD variability, with DHEAS significantly and independently associated with WBGD (P < .004). In conclusion, the negative relationship between advancing age and insulin action seems related to plasma DHEAS concentration. Differences in plasma total testosterone and IGF-1 concentrations may provide a further contribution to the relationship between DHEAS and WBGD.

Serum levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in healthy centenarians: relationship with plasma leptin and lipid concentrations, insulin action, and cognitive function

It has been demonstrated that healthy centenarians have more favorable anthropometric characteristics and insulin-mediated glucose uptake than aged subjects. The plasma insulin-like-growth factor I (IGF-I) concentration may account for such differences. Three groups of subjects were studied: 1) adults (< 50 yr; n = 30), 2) aged subjects (75-99 yr; n = 30), 3) centenarians (> 100 yr; n = 19). In all subjects, fasting plasma IGF-I, IGF-binding protein-3 (IGFBP-3), leptin, and lipid concentrations were determined; body composition was assessed by bioimpedance analysis; and insulin-mediated glucose up-take was evaluated by euglycemic hyperinsulinemic glucose clamp. IGF-I declined with advancing age, but no differences between aged subjects and centenarians were found. IGFBP-3 showed a trend similar to IGF-I, but lower values were present in centenarians than in aged subjects. Nevertheless, centenarians had a plasma IGF-I/IGFBP-3 molar ratio greater than that in aged subjects. Centenarians had also a whole body glucose disposal (WBGD) greater than that in aged subjects, but similar to that in adults. Mini Mental State Examination (27 +/- 2.1 vs. 18.3 +/- 3.1; P < 0.02) and Instrumental Activities Daily Living (26 +/- 2.6 vs. 8.4 +/- 4.1; P < 0.001) scores were significantly different in aged subjects and centenarians, respectively. In centenarians, the plasma IGF-I/IGFBP-3 molar ratio correlated with the body mass index (r = -0.55; P < 0.009); the amount of body fat (r = -0.62; P < 0.003); fat-free mass (r = 0.56; P < 0.008); fasting plasma leptin (r = -0.63; P < 0.004), triglycerides (r = -0.58; P < 0.01), free fatty acid (r = -0.64; P < 0.005), and low density lipoprotein cholesterol (r = -0.59; P < 0.009) concentrations; Mini Mental State Examination (r = 0.53; P < 0.0.03); and WBGD (r = 0.64; P < 0.005). All correlations were independent of daily fat and carbohydrate intake and WBGD (P < 0.05 for all). No significant correlations between the plasma IGF-I/IGFBP-3 molar ratio and plasma total (r = 0.31; P = NS) and high density lipoprotein cholesterol (r = 0.34; P = NS) concentrations were present. The correlation between the plasma IGF-I/IGFBP-3 molar ratio and WBGD persisted after adjustment for body fat, fasting plasma insulin concentration, daily carbohydrate and fat intake, and daily physical activity (r = 0.55; P < 0.009), but not after further adjustment for plasma free fatty acid concentration (r = 0.30; P = 0.17). In conclusion, healthy centenarians have plasma IGF-I/IGFBP-3 molar ratio greater than aged subjects. A more elevated plasma IGF-I/IGFBP-3 molar ratio might improve insulin action and plasma lipid concentration in centenarians.

Effect of oral bromocriptine administration on intraocular pressure in normotensive and glaucomatous human subjects

PURPOSE

The authors have verified the effect of orally administered bromocriptine on intraocular pressure in normotensive and glaucomatous human subjects.

METHOD

Fifteen healthy volunteers and 15 glaucomatous patients were studied. Intraocular pressure, pupil diameter, total outflow facility, systolic arterial pressure, diastolic arterial pressure, and heart rate were recorded at baseline and at 1-h intervals for 12 h after oral administration of 2. 5 mg bromocriptine or placebo, given in a randomized, double-masked, cross-over fashion. The alternate regimen was given a week later.

RESULTS

In all subjects bromocriptine significantly reduced intraocular pressure, whereas no variations in pupil diameter, systolic and diastolic arterial pressures, and heart rate were recorded. Moreover, total outflow facility, measured by conventional tonography, increased significantly both in normotensive and glaucomatous eyes.

CONCLUSIONS

These findings indicate that oral bromocriptine administration could represent a new therapy to reduce intraocular pressure in humans.