Endocrine Abstracts

The active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25D3), is synthesised by the enzyme 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-hydroxylase). The principal site of 1alpha-hydroxylase activity is in the proximal tubule of the kidney. In order to investigate renal vitamin D metabolism we have used a human proximal tubule cell line, HKC-8. We have previously shown that synthesis of 1,25D3 activity in these cells is sensitive to the concentration of calcium and North...

The physiological effects of glucocorticoids (GCs) are, at least in part, mediated by an inhibition of cell proliferation. More contentious is their anti-proliferative action and possible tumour modifying effects in neoplastic tissues. Central to the action of GCs in target tissues is the expression and function of two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) that serve to interconvert active cortisol (F) and inactive cortisone (E). 11beta-HSD type 1 (11bet...

Homeobox (HOX) genes encode proteins that are important in normal foetal development. Some of these genes such as HOXA10 also appear to be involved in haematopoiesis, tumour invasion and normal uterine function. HOXA10 is sensitively regulated by hormonal changes during the menstrual cycle. In addition, knockout mouse studies have suggested a role for HOXA10 in implantation but its precise mechanism of action remains unclear. To further investigate HOXA10 function in human rep...

Sodium transport across the human ocular non-pigmented ciliary epithelium (NPE) is fundamental to the production aqueous humour and maintenance of intraocular pressure. In sodium transporting tissues, serum and glucocorticoid regulated kinase isoform 1 (SGK1) has been identified as an early corticosteroid target gene in the activation of pre-existing epithelial sodium channels (ENaC). We previously demonstrated the presence of both the mineralocorticoid (MR) and glucocorticoid...

Patients with obesity are relatively Growth Hormone (GH) deficient. GH has potent effects on adipocyte biology, stimulating lipolysis but also promoting pre-adipocyte proliferation. Conversely, we have shown that cortisol inhibits pre-adipocyte proliferation and enhances differentiation. Furthermore, GH, acting through IGF-1, inhibits 11 beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) which converts the inactive glucocorticoid, cortisone (E) to active cortisol (F) in ad...

Heterozygous germline gain-of-function mutations of the extracellular calcium-sensing receptor (CaSR), a G-protein coupled receptor (GPCR), result in autosomal dominant hypocalcaemia type 1 (ADH1), which may cause symptomatic hypocalcaemia with low circulating parathyroid hormone (PTH) concentrations and hypercalciuria. Negative allosteric CaSR modulators, known as calcilytics, rectify the gain-of-function caused by CaSR mutations and are a potential targeted therapy for ADH1....

Background & Aims: Neuroendocrine tumours (NET) are a heterogenous group of neoplasms that secrete peptides and neuroamines. For potentially malignant gastroenteropancreatic (GEP) NET, surgical resection represents the only curative option. Ten-year imaging surveillance programs using cross sectional imaging are recommended due to long time-to-recurrence following resection. We performed a retrospective chart review to evaluate radiation exposure associated with surveillan...

Familial hypocalciuric hypercalcaemia (FHH) comprises three genetic variants: FHH types 1 and 2 are due to mutations of the calcium-sensing receptor (CaSR) and G-protein subunit alpha-11, whereas, FHH type 3 (FHH3) is caused by heterozygous mutations affecting the Arg15 residue (Arg15Cys, Arg15His, Arg15Leu) of the adaptor-related protein complex 2-sigma subunit (AP2S1), which regulates CaSR endocytosis. FHH is usually associated with mild hypercalcaemia, normal parathyroid ho...

Autosomal dominant hypocalcaemia type 1 (ADH1) is a systemic disorder of calcium homeostasis caused by gain-of-function mutations of the calcium-sensing receptor (CaSR). ADH1 may lead to symptomatic hypocalcaemia, inappropriately low parathyroid hormone (PTH) concentrations and hypercalciuria. Active vitamin D metabolites are the mainstay of treatment for symptomatic ADH1 patients, however their use predisposes to nephrocalcinosis, nephrolithiasis and renal impairment. Calcily...

Increased adiposity is associated with insulin resistance, type 2 diabetes and metabolic dysfunction. Altered adipokine secretion, changes in local and systemic glucocorticoid metabolism and increased inflammation have all been postulated as contributory mechanisms. We have previously described changes in subcutaneous adipose tissue (SAT) gene expression that are associated with obesity and glucose intolerance in cross-sectional studies. However, the effects of longitudinal ch...