ADIPSIC DIABETES INSIPIDUS: A REVIEW.

Objective: Adipsic diabetes insipidus (ADI) is a rare disorder consisting of central diabetes insipidus (CDI) and a deficient or absent thirst response to hyperosmolality. Patients with ADI experience marked morbidity and mortality. Diagnosis and management of these patients is quite challenging, even in expert hands.

Efficacy and safety of an octreotide implant in the treatment of patients with acromegaly.

Context: Acromegaly is caused by excessive GH secretion and IGF-I overproduction. The goals of treatment are to reduce GH and IGF-I values to normal and relieve the associated symptoms.

Objective: The purpose of this article was to demonstrate that an octreotide implant (84 mg) is safe and efficacious in patients with acromegaly who were responsive to prior monthly octreotide long-acting release (LAR) injections.

A subcutaneous octreotide hydrogel implant for the treatment of acromegaly.

Objective: To evaluate the pharmacokinetics, efficacy, and safety of a subcutaneous octreotide hydrogel implant in patients with acromegaly.

Methods: In 2 phase II open-label randomized studies, patients aged ≥ 18 years with confirmed acromegaly and octreotide responsiveness received one or two 52 mg hydrated implants (52 mg study) or a hydrated or nonhydrated 84 mg implant (84 mg study) inserted subcutaneously in the upper arm. Implants were removed after 6 months.

Genetic analysis in a patient presenting with meningioma and familial isolated pituitary adenoma (FIPA) reveals selective involvement of the R81X mutation of the AIP gene in the pathogenesis of the pituitary tumor.

Familial isolated pituitary adenoma (FIPA), defined as the occurrence of at least two cases of pituitary adenoma in a family that does not exhibit features of syndromic diseases, such as Carney complex or Multiple Endocrine Neoplasia type 1 or 4, is a rare autosomal dominant disease with low penetrance. About 20 % of the families with FIPA harbor inactivating mutation in aryl hydrocarbon receptor-interacting protein gene (AIP) associated with loss of heterozygosity of the same genetic locus (11q13) in the tumor. Rarely different types of extra-pituitary tumors have been described in the setting of AIP mutation-positive FIPA.

Familial isolated pituitary adenomas experience at a single center: clinical importance of AIP mutation screening.

We present four FIPA kindred discussing clinical and molecular data and emphasizing the differences regarding AIP status, as well as the importance of genetic screening. Family 1 consists of five patients harboring somatotropinomas with germline E24X mutation in AIP. In one of the patients, acromegaly was diagnosed through active screening, being cured by surgery.

Pathogenesis of familial acromegaly.

Familial acromegaly may occur as a component of syndromes of multiple endocrine neoplasia or as isolated familial somatotropinoma (IFS), which is included in the spectrum of familial isolated pituitary adenoma (FIPA). We review the pathogenesis of IFS, from the detection of loss of heterozygosity at chromosome 11q13 and establishment of linkage to this chromosome region to the description of germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene. Approximately 40% of IFS families harbor an AIP mutation.

Clinical, genetic and molecular characterization of patients with familial isolated pituitary adenomas (FIPA).

Familial pituitary adenomas can occur in MEN1 and Carney complex, as well as in the recently characterized familial isolated pituitary adenoma (FIPA) syndrome. FIPA is an autosomal dominant disease with incomplete penetrance, characterized by early-onset disease, often aggressive tumor growth and a predominance of somatotroph and lactotroph adenomas. In 20% of FIPA families, heterozygous mutations have been described in the aryl hydrocarbon receptor interacting (AIP) gene, whereas in other families the causative gene(s) are unknown.

Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects.

Objective: To identify biomarkers of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) action in human serum.

Background: The search for new markers of GH activity has received extensive attention given that the current biomarkers (IGF-1, IGFBP-3 and collagen peptides) show substantial variability in the population, and are not reliably predictive of either the physiologic effects of GH therapy or the detection of GH abuse by athletes. GH releasing hormone (GHRH) is a polypeptide synthesized in the hypothalamus that binds to receptors on pituitary somatotropes to promote the synthesis and release of GH.

Use of the metallothionein promoter-human growth hormone-releasing hormone (GHRH) mouse to identify regulatory pathways that suppress pituitary somatotrope hyperplasia and adenoma formation due to GHRH-receptor hyperactivation.

Hyperactivation of the GHRH receptor or downstream signaling components is associated with hyperplasia of the pituitary somatotrope population, in which adenomas form relatively late in life, with less than 100% penetrance. Hyperplastic and adenomatous pituitaries of metallothionein promoter-human GHRH transgenic (Tg) mice (4 and > 10 months, respectively) were used to identify mechanisms that may prevent or delay adenoma formation in the presence of excess GHRH. In hyperplastic pituitaries, expression of the late G(1)/G(2) marker Ki67 increased, whereas the proportion of 5-bromo-2'-deoxyuridine-labeled cells (S phase marker) did not differ from age-matched controls.

The role of the aryl hydrocarbon receptor-interacting protein gene in familial and sporadic pituitary adenomas.

Context: Mutations have been identified in the aryl hydrocarbon receptor-interacting protein (AIP) gene in familial isolated pituitary adenomas (FIPA). It is not clear, however, how this molecular chaperone is involved in tumorigenesis.

Objective: AIP sequence changes and expression were studied in FIPA and sporadic adenomas.

Normal physiology of hypothalamic pituitary regulation.

The anterior pituitary is a complex heterogeneous gland that exerts a central role in the integration of several regulatory systems. Its six key hormones affect peripheral glands or target tissues and are essential for reproduction, growth and development, metabolism, adaptation to external environmental changes, and stress. Each of the pituitary hormones is regulated by the central nervous system through neuroendocrine pathways involving the hypothalamus, by feedback effects from peripheral target gland hormones, and by intrapituitary mechanisms.

The empty sella.

Empty sella (ES) is an extension or herniation of the subarachnoid space into the pituitary fossa through an incompetent sellar diaphragm that is commonly associated with clinical manifestations and endocrine abnormalities. The ES may occur secondary to a variety of pituitary disorders or as a primary entity. The pathogenesis of the primary ES appears to be multifactorial though the precise mechanisms remain unclear.

Pituitary tumor enlargement in two patients with acromegaly during pegvisomant therapy.

Background: Several classes of pharmacological agents are approved for the medical therapy of acromegaly, including dopamine agonists, somatostatin analogs and a growth hormone receptor antagonist. Pegvisomant, a growth hormone receptor antagonist, suppresses IGF-1 levels into the normal range in over ninety percent of patients. However, increased tumor volume was reported in patients receiving pegvisomant who had not received prior radiotherapy.

Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog.

Context: Pulsatile GH secretion is considered important for many of the hormone's physiological effects. Short-term GHRH infusions enhance GH pulsatility and increase IGF-I, but the short GHRH half-life limits its therapeutic use. A synthetic GHRH analog (CJC-1295) that binds permanently to endogenous albumin after injection (half-life = 8 d) stimulates GH and IGF-I secretion in several animal species and in normal human subjects and enhances growth in rats.

Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse.

Although the majority of children with isolated growth hormone (GH) deficiency have a good growth response to GH-releasing hormone (GHRH), the use of this therapeutic agent is limited by its very short half-life. Indeed, we have shown that, in mice with GHRH gene ablation (GHRH knockout; GHRHKO), even twice-daily injections of a GHRH analog are unable to normalize growth. CJC-1295 is a synthetic GHRH analog that selectively and covalently binds to endogenous albumin after injection, thereby extending its half-life and duration of action.

Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.

Context: Therapeutic use of GHRH to enhance GH secretion is limited by its short duration of action.

Objective: The objective of this study was to examine the pharmacokinetic profile, pharmacodynamic effects, and safety of CJC-1295, a long-acting GHRH analog.

Design: The study design was two randomized, placebo-controlled, double-blind, ascending dose trials with durations of 28 and 49 d.

Expression analysis of hypothalamic and pituitary components of the growth hormone axis in fasted and streptozotocin-treated neuropeptide Y (NPY)-intact (NPY+/+) and NPY-knockout (NPY-/-) mice.

In the fasted and the streptozotocin (STZ)-induced diabetic male rat, hypothalamic growth hormone (GH)-releasing hormone (GHRH) mRNA levels, and pulsatile GH release are decreased. These changes are believed to be due to a rise in hypothalamic neuropeptide Y (NPY) that inhibits GHRH expression. To directly test if NPY is required for metabolic regulation of hypothalamic neuropeptides important in GH secretion, NPY, GHRH and somatostatin (SRIH) mRNA levels were determined in fasted (48 h) and STZ-treated wild-type (NPY(+/+)) and NPY-knockout (NPY(-/-)) mice by ribonuclease protection assay.

Tumor deletion mapping on chromosome 11q13 in eight families with isolated familial somatotropinoma and in 15 sporadic somatotropinomas.

Context: Isolated familial somatotropinoma (IFS) is a rare endocrine disease defined as the occurrence of at least two cases of acromegaly or gigantism in a family that does not exhibit features of Carney complex or multiple endocrine neoplasia type 1. Analysis of the multigenerational expression in families suggests that IFS is inherited as an autosomal dominant disease with incomplete penetrance. The association between the disease and loss of heterozygosity on chromosome 11q13 as well as its linkage to this region has been well established, but the IFS gene still remains unknown.

p130Rb2 and p27kip1 cooperate to control mobilization of angiogenic progenitors from the bone marrow.

Neoangiogenesis involves both bone marrow-derived myelomonocytic and endothelial progenitor cells as well as endothelial cells coopted from surrounding vessels. Cytokines induce these cells to proliferate, migrate, and exit the cell cycle to establish the vasculature; however, which cell cycle regulators play a role in these processes is largely unknown. Here, we report that mice lacking the cell cycle inhibitors p130 and p27 show defects in tumor neoangiogenesis, both in xenografts and spontaneously arising tumors.

Isolated familial somatotropinoma.

The great majority of growth hormone (GH)-secreting pituitary tumors are sporadic, though a few occur with a familial aggregation, either as a component of multiple endocrine neoplasia, type 1 (MEN1) or Carney Complex, or when unassociated with other tumors, as isolated familial somatotropinomas (IFS). This report reviews the clinical and genetic information available from the 46 families reported to date with the latter syndrome. In contrast to sporadic tumors, GH-secreting tumors in IFS occur at an earlier age, especially when all affected family members are from a single generation.

Familial acromegaly.

Most pituitary tumors are sporadic, though a few occur with a familial aggregation. Three distinct syndromes have been recognized to date: multiple endocrine neoplasia, type I (MEN-1), Carney complex (CNC), and isolated familial somatotropinomas (IFS). Pituitary tumor types in MEN-1 are similar to those occurring sporadically.

A meiotic recombination in a new isolated familial somatotropinoma kindred.

We report here the genetic findings of a new isolated familial somatotropinoma (IFS) kindred in which the mother (subject I:2) and one daughter (subject II:2) are affected; their ages at diagnosis were 25 and 14 years respectively. Additionally, patient I:2 developed virilization due to an androgen-secreting adrenocortical mass, presenting clinical and molecular features of sporadic adrenal carcinoma. To genotype this family and to narrow down the candidate interval of the putative IFS gene at 11q13, we performed haplotyping on the DNA from all five members of the family and allelotyping of one available somatotropinoma using polymorphic microsatellite markers from chromosome region 11q12.

Isolated familial somatotropinomas: clinical and genetic considerations.

The majority of somatotropinomas (GH-secreting pituitary adenomas) are sporadic, through a few occur with a familial aggregation, either as a component of multiple endocrine neoplasia, type 1 (MEN1) or Carney complex, or when unassociated with other tumors, as isolated familial somatotropinomas (IFS). The latter is a rare disorder associated with loss of heterozygosity (LOH) on chromosome 11q13, the locus of the MEN1 gene. However, MEN1 sequence and expression are normal, suggesting the presence of another tumor suppressor gene within this locus that affects somatotrope proliferation.

Growth hormone-releasing hormone and pituitary development, hyperplasia and tumorigenesis.

Growth hormone-releasing hormone (GHRH) is essential for expansion of the somatotrope lineage during pituitary development, and excessive GHRH secretion and/or action results in unregulated somatotrope proliferation and neoplastic transformation. Our understanding of the molecular and morphological bases for these effects from both animal and clinical studies has greatly increased during the past decade. However, many features of the cellular pathways remain to be defined, including the interaction of other genes in the multistep process of somatotrope tumorigenesis.