A novel germline mutation in the aryl hydrocarbon receptor-interacting protein (AIP) gene in an Italian family with gigantism

PURPOSE

Acromegaly usually occurs as a sporadic disease, but it may be a part of familial pituitary tumor syndromes in rare cases. Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene have been associated with a predisposition to familial isolated pituitary adenoma. The aim of the present study was to evaluate the AIP gene in a patient with gigantism and in her relatives.

METHODS

Direct sequencing of AIP gene was performed in fourteen members of the family, spanning among three generations.

RESULTS

The index case was an 18-year-old woman with gigantism due to an invasive GH-secreting pituitary adenoma and a concomitant tall-cell variant of papillary thyroid carcinoma. A novel germline mutation in the AIP gene (c.685C>T, p.Q229X) was identified in the proband and in two members of her family, who did not present clinical features of acromegaly or other pituitary disorders. Eleven subjects had no mutation in the AIP gene. Two members of the family with clinical features of acromegaly refused either the genetic or the biochemical evaluation. The Q229X mutation was predicted to generate a truncated AIP protein, lacking the last two tetratricopeptide repeat domains and the final C-terminal α-7 helix.

CONCLUSIONS

We identified a new AIP germline mutation predicted to produce a truncated AIP protein, lacking its biological properties due to the disruption of the C-terminus binding sites for both the chaperones and the client proteins of AIP.

The onset time of amiodarone-induced thyrotoxicosis (AIT) depends on AIT type

OBJECTIVE

Considering the different pathogenic mechanisms of the two main forms of amiodarone-induced thyrotoxicosis (AIT), we ascertained whether this results in a different onset time as well.

DESIGN AND METHODS

We retrospectively analyzed the clinical records of 200 consecutive AIT patients (157 men and 43 women; mean age 62.2±12.6 years) referred to our Department from 1987 to 2012. The onset time of AIT was defined as the time elapsed from the beginning of amiodarone therapy and the first diagnosis of thyrotoxicosis, expressed in months. Factors associated with the onset time of AIT were evaluated by univariate and multivariate analyses.

RESULTS

The median onset time of thyrotoxicosis was 3.5 months (95% CI 2-6 months) in patients with type 1 AIT (AIT1) and 30 months (95% CI 27-32 months, P<0.001) in those with type 2 AIT (AIT2). Of the total number of patients, 5% with AIT1 and 23% with AIT2 (P=0.007) developed thyrotoxicosis after amiodarone withdrawal. Factors affecting the onset time of thyrotoxicosis were the type of AIT and thyroid volume (TV).

CONCLUSIONS

The different pathogenic mechanisms of the two forms of AIT account for different onset times of thyrotoxicosis in the two groups. Patients with preexisting thyroid abnormalities (candidate to develop AIT1) may require a stricter follow-up during amiodarone therapy than those usually recommended. In AIT1, the onset of thyrotoxicosis after amiodarone withdrawal is rare, while AIT2 patients may require periodic tests for thyroid function longer after withdrawing amiodarone.

Effects of cocaine on the hypothalamic-pituitary-adrenal axis

INTRODUCTION

Cocaine hydrochloride is a psychoactive substance extracted from the leaves of plants called Erythroxylum coca. Cocaine is the second most commonly used drug in the world after cannabis; 20 % of cocaine users will become long-term cocaine-dependent patients. Different routes of administration may be recognized: smokable modality, intranasal and intravenous. Cocaine is a potent stimulant of the sympathetic nervous system and causes structural changes on the brain, heart, lung, liver and kidney. It has long been known that use of cocaine may produce alterations to the endocrine system. Research on behavioral and neuroendocrine effects of cocaine dates back several years ago and has increasingly focused on alterations of the hypothalamic-pituitary-adrenal (HPA) axis, which appears to be the chief target of cocaine effects.

STUDIES

Animal (mainly rats and monkeys) and human studies have clearly shown a close relation between cocaine consumption and overdrive of the HPA axis. Such activation is likely involved, though via a still undefined mechanism, in the behavioral and cardiovascular changes of drug abusers as well as in the reinforcement/relapse phenomena. Further studies of the pathophysiology of cocaine addicts will help to devise new therapeutic strategies for these patients.

Effects of amiodarone, thyroid hormones and CYP2C9 and VKORC1 polymorphisms on warfarin metabolism: a review of the literature

OBJECTIVE

To review the literature regarding the interaction among amiodarone therapy, thyroid hormone levels, and warfarin metabolism.

METHODS

A 73-year-old male with type 2 after describing an unusual case of amiodarone-induced thyrotoxicosis (AIT) who experienced a severe rise in international normalized ratio (INR) values after initiating warfarin therapy due to an unusual combination of excessive thyroid hormones, amiodarone therapy, and a genetic abnormality affecting warfarin metabolism.

RESULTS

Genetic analysis revealed that the patient was CYP2C9*2 wild-type, CYP2C9*3/*3 homozygous mutant, and VKORC1*3/*3 homozygous mutant. A review of the literature revealed that both mutations can independently affect warfarin metabolism. In addition, amiodarone therapy and the presence of thyrotoxicosis per se can affect warfarin metabolism and reduce the dose needed to maintain INR in the therapeutic range. The association of the 2 genetic polymorphisms in a patient with AIT is extremely rare and strongly impairs warfarin metabolism, exposing the patient to a high risk of overtreatment.

CONCLUSIONS

In patients with AIT, warfarin therapy should be gradually introduced, starting with a very low dose, because of the significant risk of warfarin overtreatment. Whether the genetic analysis of CYP2C9 and VKORC1 polymorphisms should be routinely performed in AIT patients remains conjectural.

Growth hormone is necessary for the p53-mediated, obesity-induced insulin resistance in male C57BL/6J x CBA mice

Insulin resistance is a key marker of both obesity and GH excess. The purpose of the study was to assess the role of GH on p53-mediated insulin resistance of male mice with obesity due to a high-fat diet. C57BL/6J × CBA male mice fed on a high-fat diet (Obe) were studied; male mice fed a normal diet (Lean) or transgenic mice for bovine GH under the same genetic background (Acro) served as controls. The convergence of p53 and GH pathways was evaluated by Western blot. Obe mice had insulin resistance, which was sustained by a selective increased expression of p53 in adipose tissue. Normal insulin sensitivity was restored, and adipose p53 expression normalized when the GH pathway was blocked. Only the adipose p53 expression was sensitive to the GH blockage, which occurred through the p38 pathway. Adipose tissue of Obe mice had a coordinate overexpression of suppressors of cytokine signal 1-3 and signal transducers and activators of transcription-1, -3, and -5b, not different from that of Acro mice, suggesting an increased sensitivity of adipose tissue to GH. On the contrary, Lean mice were unaffected by changes of GH action. GH seems to be necessary for the increased adipose p53 expression and for insulin resistance of obese mice.

Comparison of the effects of primary somatostatin analogue therapy and pituitary adenomectomy on survival in patients with acromegaly: a retrospective cohort study

OBJECTIVE

Acromegalic patients have an increased risk of mortality. The objective of this study was to compare the effect of different therapies for acromegaly on mortality.

DESIGN AND METHODS

The mortality rate of 438 consecutive acromegalic patients was compared with that of the general population using the standardized mortality ratio (SMR); the effect of different therapies on survival was evaluated using Cox regression analysis.

RESULTS

Twenty patients (4.5%) died between 1999 and 2009. Age- and sex-adjusted SMR was 0.70 (95% CI 0.43-1.08). The Cox regression analysis revealed that, in the whole population, both general risk factors (age and physical status) and specific factors for acromegaly (macroadenoma, hypopituitarism and uncontrolled disease) were associated with death. The most compromised patients at diagnosis had a higher mortality rate (P=0.001), which also occurred in patients with controlled acromegaly. Death occurred in 2.4% (adenomectomy), 2.6% (adenomectomy followed by somatostatin analogue (SSA) therapy) and 11.4% (SSA therapy as the primary therapy) of the patients. The risk of death was higher in patients receiving SSA therapy as the primary therapy (hazard ratio (HR) 5.52, 95% CI 1.06-28.77, P=0.043) than in all patients submitted to adenomectomy; however, a higher risk of death occurred only in diabetic patients treated with SSAs alone (HR 21.94, 95% CI 1.56-309.04, P=0.022). Radiotherapy was associated with an increased risk of mortality, which occurred in patients with the more locally advanced disease.

CONCLUSIONS

Therapies for acromegaly and comorbidities have lowered the risk of mortality to the level of the general population; the effect of SSA therapy alone or that following pituitary adenomectomy was comparable to that of curative neurosurgery on survival in non-diabetic patients; on the contrary, SSA therapy as the primary therapy may be less effective than adenomectomy in reducing mortality rate in diabetic patients.

Serum factors associated with precancerous colonic lesions in acromegaly

BACKGROUND

Insulin, 25-hydroxy vitamin D3 [25(OH)D3] and folate have been differently associated with a risk of colonic neoplasms in the general population. Acromegalic patients have an increased risk of colorectal tumors and an association between fasting insulin concentrations and colonic lesions has been reported. However, it is unknown whether insulin, 25(OH)D3, folate, and homocysteine interact to determine the risk of colonic tumors in acromegaly.

AIM

To investigate whether serum insulin, 25(OH)D3, folate, and homocysteine concentrations were associated with precancerous colonic lesions in acromegalic patients.

MATERIAL AND METHODS

A cohort of 146 consecutive acromegalic patients was evaluated for colonoscopy findings and fasting insulin, 25(OH)D3, folate, and homocysteine levels. A preliminary study was conducted in 9 naïve acromegalic patients to evaluate the effect of somatostatin analogues (SSA) on serum levels of those factors.

RESULTS

Insulin reduced during SSA whereas the other factors did not change. In the cohort study, colonic lesions (14 adenomas; 32 hyperplastic polyps) were detected in 46 patients. Fasting insulin, 25(OH)D3, folate, and homocysteine levels did not differ in patients with or without colonic adenomas. High folate levels were associated with a lower risk of developing precancerous colonic lesions at the multivariate analysis, when corrected by age, gender, disease activity and SSA therapy.

CONCLUSIONS

Serum insulin, 25(OH)D3 and homocysteine serum concentrations do not seem to influence the development of precancerous colonic lesions in acromegalic patients, while higher folate levels may be associated with a lower risk of colonic lesions.

Effects of medical therapies for acromegaly on glucose metabolism

OBJECTIVE

Abnormalities of glucose metabolism are common findings of acromegaly. However, robust evidence on whether therapy with somatostatin analogs (SSAs) or pegvisomant (PEG) differently affects glucose metabolism is lacking. The purpose of this study was to evaluate the effects of therapy with SSAs, PEG, or their combination on glucose metabolism in a large series of acromegalic patients.

DESIGN

This was a historical-prospective study. Among 50 consecutive acromegalic patients under SSA therapy, acromegaly in 19 patients was controlled. PEG used in combination with SSA therapy allowed the control of acromegaly in the remaining 31 patients and was then continued as monotherapy in 18 patients.

METHODS

The following parameters were evaluated at the diagnosis of acromegaly and during DIFFERENT TREATMENTS: fasting plasma glucose (FPG) and insulin concentrations, insulin sensitivity (QUICK-I), homeostasis model assessment of insulin resistance (HOMA2-IR), and plasma glucose and insulin concentrations during the oral glucose tolerance test (OGTT). Comparison was made using analysis for paired data.

RESULTS

Insulin resistance improved when acromegaly was controlled with therapy with SSAs, PEG, or SSA+PEG. However, FPG concentrations were higher during SSA therapy (alone or combined with PEG) than at the diagnosis of acromegaly, even when corrected for disease activity, whereas they were reduced during PEG therapy. Mean glucose concentrations during the OGTT were higher in patients receiving SSA therapy than in those receiving PEG therapy. In addition, the prevalence of diabetes or impaired glucose tolerance was higher during SSA therapy than at diagnosis or during PEG therapy and was not influenced by disease control.

CONCLUSIONS

Medical therapies for acromegaly reduce insulin resistance and increase insulin sensitivity; on the contrary, glucose indexes may be differently affected by SSA or PEG therapy.

Impact of GH replacement therapy on sleep in adult patients with GH deficiency of pituitary origin

OBJECTIVES

We previously reported that adult patients with GH deficiency (GHD) due to a confirmed or likely pituitary defect, compared with healthy controls individually matched for age, gender, and BMI, have more slow-wave sleep (SWS) and higher delta activity (a marker of SWS intensity). Here, we examined the impact of recombinant human GH (rhGH) therapy, compared with placebo, on objective sleep quality in a subset of patients from the same cohort.

DESIGN

Single-blind, randomized, crossover design study.

METHODS

Fourteen patients with untreated GHD of confirmed or likely pituitary origin, aged 22-74 years, participated in the study. Patients with associated hormonal deficiencies were on appropriate replacement therapy. Polygraphic sleep recordings, with bedtimes individually tailored to habitual sleep times, were performed after 4 months on rhGH or placebo.

RESULTS

Valid data were obtained in 13 patients. At the end of the rhGH treatment period, patients had a shorter sleep period time than at the end of the placebo period (479±11 vs 431±19 min respectively; P=0.005), primarily due to an earlier wake-up time, and a decrease in the intensity of SWS (delta activity) (559±125 vs 794±219 μV(2) respectively; P=0.048).

CONCLUSIONS

Four months of rhGH replacement therapy partly reversed sleep disturbances previously observed in untreated patients. The decrease in delta activity associated with rhGH treatment adds further evidence to the hypothesis that the excess of high-intensity SWS observed in untreated pituitary GHD patients is likely to result from overactivity of the hypothalamic GHRH system due to the lack of negative feedback inhibition by GH.

Ectopic expression of FSH receptor isoforms in neoplastic but not in endothelial cells from pancreatic neuroendocrine tumors

FSH receptor (FSHR) expression is restricted to gonads, where it drives FSH-dependent cell differentiation; in addition, FSHR plays an important role in the regulation of ovarian angiogenesis. Recently, FHSR expression has been shown in blood vessels of various tumors. However, pancreatic neuroendocrine tumors (p-NET), which have high-degree blood supply, were not included in that study. The aim of this study was to evaluate FSHR expression in p-NET. FSHR expression was evaluated in tumor samples from 30 patients with p-NET by immunohistochemistry and Western blot; fluorescence microscopy was used to localize FSHR in specific cells from tissue samples. von Willebrand factor (vWF) and chromograninA (chrA) was used as blood vessel and NET cells marker, respectively, to co-localize FSHR. FSHR expression was detected in all p-NET by immunohistochemistry. Western blot confirmed FSHR expression on p- NET although different FSHR isoforms, ranging from 240 kD to 55 kD were found in the samples studied. Surprisingly, FSHR co-localized with chrA but not with vWF, suggesting that neoplastic cells of neuroendocrine origin rather than blood vessels expressed FSHR. No relationship was found between degree of FSHR expression and histology of p-NET. FSHR may be aberrantly expressed in neoplastic cells from p-NET and not in tumor blood vessels; however, its biological significance as well as its clinical relevance remains to be elucidated.

Usefulness of salivary cortisol in the diagnosis of hypercortisolism: comparison with serum and urinary cortisol

OBJECTIVE

Several tests have been proposed to diagnose patients with Cushing's syndrome (CS). The aims of the study were: i) to evaluate the performance of salivary cortisol (SC) in hypercortisolism and ii) to compare SC with serum cortisol (SeC) and urinary cortisol.

DESIGN AND PATIENTS

This was a diagnostic study. Twenty-seven patients with untreated Cushing's disease (CD untr), 21 women consuming oral contraceptive pill (OCP), 18 pregnant women, and 89 healthy subjects (controls) were enrolled.

METHODS

SC and SeC at baseline and after the low-dose dexamethasone suppression test (LDDST) and urinary free cortisol (UFC) were measured.

RESULTS

Midnight SC had a sensitivity of 100% in the CD untr group and a specificity of 97.7% in the controls. Specificity remained high (95.2%) in women taking OCP, while in pregnant women, it decreased to 83.3%. SC after the LDDST showed a sensitivity of 96.3% in the CD untr group; specificity was 97.7% in the controls and 90.5% in OCP women. Midnight SeC had a sensitivity of 100% in the CD untr group. SeC after the LDDST had a sensitivity of 100% in the CD untr group while specificity was 97.7% in the controls and 61.9% in women taking OCP. For UFC, sensitivity was 92.6% in the CD untr group while specificity was 97.7% in the controls and 100% in the OCP group.

CONCLUSIONS

SC is a reliable parameter for the diagnosis of severe hypercortisolism, with high sensitivity and specificity. In women during pregnancy or taking OCP, the measurement of SC, identifying the free fraction, could be helpful to exclude CS.

Pituitary autoimmunity in patients with diabetes mellitus and other endocrine disorders

OBJECTIVE

Pituitary autoimmunity is often found in association with other endocrine autoimmune or non-autoimmune diseases. Aim of the study was to assess the prevalence of serum pituitary antibodies (PitAb) in patients with Type 1 diabetes mellitus (T1DM) or Type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

In this casecontrol study 111 patients with T1DM, 110 patients with T2DM, and 214 healthy controls were enrolled in a tertiary referral center. Pituitary, thyroperoxidase, thyroglobulin, 21-hydroxylase, and parietal cell antibodies were assessed in all cases. Endocrine function was further assessed by basal hormone measurement and by dynamic tests, as well as a pituitary magnetic resonance imaging (MRI) was performed in those patients found positive for PitAb.

RESULTS

PitAb prevalence was higher in T1DM (4 out of 111, 3.6%) than in T2DM (0 out of 110, p=0.045) and in healthy subjects (1 out of 214, 0.5% p=0.029). Prevalence of other autoimmune diseases was significantly higher in patients with T1DM (45 out of 111, 40.5%) when compared with patients with T2DM (18 out of 110 T2DM, 16.3%, p<0.001). Patients with T1DM and PitAb positivity were found with a pituitary lesion at MRI in 2 cases and pituitary dysfunction in one case.

CONCLUSIONS

A significant association between pituitary autoimmunity and T1DM was found, in particular in subjects with one or more other endocrine autoimmune diseases.

Total thyroidectomy in patients with amiodarone-induced thyrotoxicosis and severe left ventricular systolic dysfunction

CONTEXT

Patients with amiodarone-induced thyrotoxicosis (AIT) and left ventricular (LV) systolic dysfunction have a high mortality rate. Usually, medical therapy is the first choice for AIT patients, whereas the role of the thyroidectomy is unsettled.

OBJECTIVE

The objective of the study was to evaluate the effect of a total thyroidectomy on cardiac function and survival of AIT patients with severe LV systolic dysfunction.

DESIGN

This was a retrospective cohort study.

SETTINGS

The study was conducted at a tertiary university center.

PATIENTS

All AIT patients (n=24; nine patients with type 1 AIT, 15 patients with type 2 AIT) referred to the Department of Endocrinology and submitted to a total thyroidectomy at the Department of Surgery, both at the University of Pisa, during the years 1997-2010.

INTERVENTION

The intervention was a total thyroidectomy.

MAIN OUTCOME MEASURE

LV ejection fraction (EF) after the thyroidectomy and survival in December 2011 were measured.

RESULTS

All enrolled patients had previously undergone to medical treatment for AIT, as appropriate, without achieving euthyroidism. Patients with moderate to severe LV systolic dysfunction (EF<40%, group 1, n=9) or with mild systolic dysfunction (40%≤EF≤50%, group 2, n=5) were compared with patients with normal systolic function (EF>50%, group 3, n=10). Two months after thyroidectomy, under levothyroxine replacement therapy, LVEF improved in patients with LV systolic dysfunction, particularly in those of group 1, in whom it increased from 28.2±7.2 to 38.3±6% (P=0.007). On the contrary, LVEF did not significantly change in group 3 (from 57.1±3.0 to 59.8±6.6%, P=0.242). The mean follow-up was 67±42 months. No death occurred during and 2 months after surgery. One death occurred in one patient of group 1, 30 months after the thyroidectomy, due to acute myocardial infarction. No patient had relevant complications of thyroidectomy.

CONCLUSIONS

Total thyroidectomy, by rapidly restoring euthyroidism, may improve cardiac function and reduce the risk of mortality in AIT patients with severe LV dysfunction.