Searchable abstracts of presentations at key conferences in endocrinology

ea0005p141 | Endocrine Tumours and Neoplasia | BES2003

Abnormal expression of 11beta-hydroxysteroid dehydrogenase 2 in primary cultures of human pituitary adenomas

Rabbitt E , Bujalska I , Stewart P , Hewison M , Gittoes N

Glucocorticoids (GCs) mediate many of their physiological effects through inhibition of cell proliferation. More contentious is the antiproliferative action of GCs and their possible tumour-modifying effects in neoplastic tissues. However, in recent studies we have shown that 'prereceptor' metabolism of GCs by the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) is a pivotal determinant of cell proliferation and tumour formation. Two isozymes of 11beta-HSD interconvert ...

ea0005p168 | Growth and Development | BES2003

Differential regulation of the ghrelin promoter in WRL68 and HEK293 cells

Macartney D , Hughes B , Stewart P , Sheppard M , Toogood A

It is now evident that ghrelin is more than just a growth hormone (GH) secretagogue; it plays an important role in energy homeostasis, increasing food intake and fat deposition, has cardiovascular effects, and inhibits cell proliferation.Ghrelin mRNA expression is widespread in human tissues, but little is known about the molecular mechanisms and signals that regulate gene expression at the transcriptional level. To address this we cloned and sequenced a 4kb region upstrea...

ea0005p195 | Reproduction | BES2003

Oxygen tension regulates placental 11beta-hydroxysteroid dehydrogenase type 2

Driver P , Hewison M , Kilby M , Stewart P

In humans the most abundant source of 11 beta-hydroxysteroid dehydrogenase type 2 is the placenta, notably placental trophoblast. This enzyme catalyses the conversion of cortisol (F) to cortisone (E) and is thought to protect the fetus from maternal hypercortisolaemia, thereby impacting on fetal growth and development. During gestation placental trophoblast is exposed to dramatic changes in oxygen tensions ranging from ~2% - 12%, changes thought to be pivotal in stimulating an...

ea0005p216 | Steroids | BES2003

Adipocyte size increases with BMI, but is unrelated to 11 beta-hydroxysteroid dehydrogenase type 1 expression

Tomlinson J , Bujalska I , Collard M , Stewart P

Patients with Cushing's syndrome develop florid, but reversible central obesity. However, circulating cortisol levels are not elevated in simple obesity. Within human adipose tissue, the enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is highly expressed and converts inactive glucocorticoid, cortisone to active cortisol. Rodents over-expressing 11beta-HSD1 in adipocytes develop central obesity exclusively as a result of increased adipocyte size. Whilst it has ...

ea0005p219 | Steroids | BES2003

Mutagenesis studies on recombinant human 11beta-hydroxysteroid dehydrogenase type 1

Walker E , Hughes S , Ride J , Hewison M , Stewart P

11beta-hydroxysteroid dehydrogenase type 1 (11B-HSD1) catalyses the inter-conversion of cortisone and cortisol, and has been implicated in the pathogenesis of a number of disorders including insulin resistance and obesity. The enzyme is a glycosylated membrane-bound protein, located in the lumen of the endoplasmic reticulum (ER) and has proved difficult to purify in an active state. Previously, we reported the successful expression and purification of human 11B-HSD1 from E. co...

ea0005p226 | Steroids | BES2003

Identification of glucocorticoid target genes in human subcutaneous and omental adipose tissue using microarray analysis

Bujalska I , Montague C , Smith D , Stewart P

The central obese phenotype characteristic of Cushing's syndrome emphasises the role of glucocorticoids (GC) in regulating adipose tissue mass and distribution. We have shown that GCs stimulate adipocyte differentiation, but equally inhibit adipose stromal cell (ASC) proliferation. These effects are regulated at a pre-receptor level through 11beta-hydroxysteroid dehydrogenase type 1, but the 'post-receptor' signalling pathways remain unclear. To define novel GC targets in huma...

ea0003oc12 | Endocrine Neoplasia | BES2002

Ghrelin inhibits proliferation of breast cell lines acting via the growth hormone secretagogue receptor (GHS-R)

Taylor J , Hughes B , Sheppard M , Stewart P , Toogood A

Ghrelin, the natural ligand for the GHS-R, modulates proliferation in cell lines derived from malignant breast tissue. It has been suggested that this action is independent of the GHS-R. We have previously demonstrated that MCF7 cells expressed ghrelin but not GHS-R mRNA and MDA-MB231 cells expressed GHS-R but not ghrelin mRNA. To determine whether ghrelin modulates proliferation in MCF7 and MDA-MB231 cells we performed proliferation assays treating with saline, 1 and 10nM ghr...

ea0003oc36 | Hormone Action | BES2002

Increasing fracture risk with age: Possible role of local corticosteroid generation

Cooper M , Rabbitt E , Hewison M , Stewart P

The risk of bone fracture at most skeletal sites rises rapidly with age. Changes in bone mass account for only a small part of this increased risk - an additional factor is the progressive reduction in the ability to form new bone. This decrease in bone formation and increased fracture risk is reminiscent of changes seen with glucocorticoid excess, however, circulating corticosteroid levels do not change with age. We have proposed that local rather than circulating levels of c...

ea0003oc38 | Hormone Action | BES2002

Autocrine generation of androgens within adipose tissue: Implications for polycystic ovarian syndrome (PCOS)

Sinha B , Tomlinson J , Bujalska I , Hewison M , Stewart P

The most robust biochemical marker for the diagnosis of PCOS is hyperandrogenism (androstenedione, testosterone), thought to originate from the ovaries and/or adrenals. However the change in circulating androgen/LH ratios with increasing body mass in women with PCOS suggests the autocrine generation of androgens within adipose tissue itself. The enzyme 17beta hydroxysteroid dehydrogenase (17betaHSD) which has seven human isoforms is an important regulator of sex steroid metabo...

ea0003p204 | Neuroendocrinology | BES2002

Growth hormone (GH) deficiency in adults treated for acute lymphoblastic leukaemia (ALL) in childhood

Ayuk J , McGregor E , Mann J , Stewart P , Toogood A

The number of patients treated for malignant disease in childhood surviving into adulthood is increasing, but success is tempered by long-term side-effects of chemotherapy and radiotherapy; 40% develop one or more endocrinopathy. ALL is a common childhood malignancy treated with chemotherapy and cranial irradiation. The latter causes anterior pituitary hormone deficiencies, most frequently GH deficiency.We have determined GH status in 13 patients treate...