Late presentation of hyperandrogenism in pregnancy: clinical features and differential diagnosis

Background

Hyperandrogenic states in pregnancy are rare but arise most commonly due to new-onset ovarian pathology in pregnancy. We describe the case of a young woman who presented in the latter half of her pregnancy with features of hyperandrogenism. We review the biochemical and imaging findings and discuss the differential diagnosis.

Case presentation

A 26-year-old woman presented in the later part of her pregnancy with widespread hirsutism. Biochemical testing confirmed hyperandrogenism (testosterone, 13.7 nmol/l and second-trimester pregnancy range, 0.9–4.9 nmol/l), although she had no history of menstrual disturbance, hirsutism or acne prior to conception. Radiological evaluation (ultrasound and magnetic resonance imaging) revealed multiple cystic lesions in both ovaries, leading to a presumptive diagnosis of hyperreactio luteinalis (HL). The implications of maternal hyperandrogenism on foetal virilisation were considered and the patient was counselled appropriately. She delivered a healthy baby boy uneventfully. Androgen levels, hirsutism and acne normalised within a few weeks of delivery.

Conclusion

HL can occur at any stage of pregnancy and is an important differential diagnosis in pregnant patients with features of androgen excess. Most cases regress spontaneously after delivery and major interventions are usually not needed.

Learning points

Hyperandrogenism in pregnancy is rare.

Clinical features are similar to the non-pregnant state in the mother but virilisation in the foetus can have profound consequences.

HL and pregnancy luteoma are the most common ovarian pathologies leading to hyperandrogenism in pregnancy.

Spontaneous regression occurs in the post-partum period in the vast majority of cases and surgery is only required for local complications.

Development of a rapid assay for the analysis of serum cortisol and its implementation into a routine service laboratory

Background

LC-MS/MS is rapidly becoming the technology of choice for measuring steroid hormones. We have developed a rapid LC-MS/MS assay for the routine analysis of serum cortisol. We have used this assay to investigate the effects of gender and exogenous steroid interference on the immunoassay measurement of serum cortisol.

Methods

Zinc sulphate (40  µL) was added to 20  µL of sample. This was vortexed for 10 s followed by the addition of 100  µL of internal standard in methanol. Following mixing and centrifugation, 10  µL of sample was injected into an Acquity LC system coupled to a Quattro Premier tandem mass spectrometer. Serum samples ( n = 149) were analysed by LC-MS/MS and two commercial immunoassays. Results were then compared for all samples and for gender differences. A further set of serum samples ( n = 171) was analysed by the LC-MS/MS assay and a GC-MS assay.

Results

Cortisol had a retention time of 0.98 min and the assay had an injection-to-injection time of 2.6 min per sample. Mean recovery was 99% and mean CV was 8%. The immunoassays gave comparisons of: Roche = 1.23 × LC-MS/MS −1.12 nmol/L and Abbott = 0.94 × LC-MS/MS + 11.97. The comparison with GC-MS showed LC-MS/MS = 1.11 × GC-MS – 22.90.

Discussion

We have developed an LC-MS/MS assay for serum cortisol analysis that is suitable for routine clinical use and has been in use in our laboratory for 12 months. The availability of this assay will give more reliable results in patients receiving exogenous steroid therapy.

Quality of life in adults with congenital adrenal hyperplasia relates to glucocorticoid treatment, adiposity and insulin resistance: United Kingdom Congenital adrenal Hyperplasia Adult Study Executive (CaHASE)

CONTEXT

Quality of life (QoL) has been variously reported as normal or impaired in adults with congenital adrenal hyperplasia (CAH). To explore the reasons for this discrepancy we investigated the relationship between QoL, glucocorticoid treatment and other health outcomes in CAH adults.

METHODS

Cross-sectional analysis of 151 adults with 21-hydroxylase deficiency aged 18-69 years in whom QoL (assessed using the Short Form Health Survey), glucocorticoid regimen, anthropometric and metabolic measures were recorded. Relationships were examined between QoL, type of glucocorticoid (hydrocortisone, prednisolone and dexamethasone) and dose of glucocorticoid expressed as prednisolone dose equivalent (PreDEq). QoL was expressed as z-scores calculated from matched controls (14,430 subjects from UK population). Principal components analysis (PCA) was undertaken to identify clusters of associated clinical and biochemical features and the principal component (PC) scores used in regression analysis as predictor of QoL.

RESULTS

QoL scores were associated with type of glucocorticoid treatment for vitality (P=0.002) and mental health (P=0.011), with higher z-scores indicating better QoL in patients on hydrocortisone monotherapy (P<0.05). QoL did not relate to PreDEq or mutation severity. PCA identified three PCs (PC1, disease control; PC2, adiposity and insulin resistance and PC3, blood pressure and mutations) that explained 61% of the variance in observed variables. Stepwise multiple regression analysis demonstrated that PC2, reflecting adiposity and insulin resistance (waist circumference, serum triglycerides, homeostasis model assessment of insulin resistance and HDL-cholesterol), related to QoL scores, specifically impaired physical functioning, bodily pain, general health, Physical Component Summary Score (P<0.001) and vitality (P=0.002).

CONCLUSIONS

Increased adiposity, insulin resistance and use of prednisolone or dexamethasone are associated with impaired QoL in adults with CAH. Intervention trials are required to establish whether choice of glucocorticoid treatment and/or weight loss can improve QoL in CAH adults.

Method-specific serum cortisol responses to the adrenocorticotrophin test: comparison of gas chromatography-mass spectrometry and five automated immunoassays

OBJECTIVE

The serum cortisol response to the adrenocorticotrophin (ACTH) test is known to vary significantly by assay, but lower reference limits (LRL) for this response have not been established by the reference gas chromatography-mass spectrometry (GC-MS) method or modern immunoassays. We aimed to compare the normal cortisol response to ACTH stimulation using GC-MS with five widely used immunoassays.

DESIGN, PATIENTS AND MEASUREMENTS

An ACTH test (250 μg iv ACTH1-24 ) was undertaken in 165 healthy volunteers (age, 20-66 years; 105 women, 24 of whom were taking an oestrogen-containing oral contraceptive pill [OCP]). Serum cortisol was measured using GC-MS, Advia Centaur (Siemens), Architect (Abbott), Modular Analytics E170 (Roche), Immulite 2000 (Siemens) and Access (Beckman) automated immunoassays. The estimated LRL for the 30 min cortisol response to ACTH was derived from the 2·5th percentile of log-transformed concentrations.

RESULTS

The GC-MS-measured cortisol response was normally distributed in males but not females, with no significant gender difference in baseline or post-ACTH cortisol concentration. Immunoassays were positively biased relative to GC-MS, except in samples from women on the OCP, who showed a consistent negative bias. The LRL for cortisol was method-specific [GC-MS: 420 nm; Architect: 430 nm; Centaur: 446 nm; Access 459 nm; Immulite (2000) 474 nm] and, for the E170, also gender-specific (female: 524 nm; male 574 nm). A separate LRL is necessary for women on the OCP.

CONCLUSIONS

Normal cortisol responses to the ACTH test are influenced significantly by assay and oestrogen treatment. We recommend the use of separate reference limits in premenopausal women on the OCP and warn users that cortisol measurements in this subgroup are subject to assay interference.

Adult testosterone and calculated free testosterone reference ranges by tandem mass spectrometry

BACKGROUND

Testosterone is measured for the investigation of female hyperandrogenism and male hypogonadism. Liquid chromatography-tandem mass spectrometry (tandem MS) is becoming the method of choice but comprehensive reference ranges are lacking.

METHODS

Testosterone was measured by tandem MS on 90 healthy women, 67 young healthy men and pregnant women (59 first trimester and 60 second trimester).

RESULTS

The male, male calculated free, first trimester and second trimester testosterone reference ranges (derived using the antilog of mean ± 1.96 SD of log transformed data) were 10.6-31.9, 0.23-0.63, 0.6-4.9 and 0.9-4.9 nmol/L, respectively. The female testosterone upper reference range limit, derived non-parametrically from the 97.5th centile, was <1.7 nmol/L.

CONCLUSIONS

We have derived tandem MS testosterone reference ranges to support clinical services.

Glucocorticoid treatment regimen and health outcomes in adults with congenital adrenal hyperplasia

BACKGROUND

Adults with congenital adrenal hyperplasia (CAH) are treated with a wide variety of glucocorticoid treatment regimens.

OBJECTIVE, DESIGN AND METHODS

To test whether drug dose and timing of glucocorticoid treatment regimen impacts on health outcomes. This was a cross-sectional study of 196 adult CAH patients in whom treatment and health outcomes were measured. Glucocorticoid dose was converted to prednisolone dose equivalent (PreDEq) using three published formulae. Associations between the type of glucocorticoid regimen and PreDEq with specific health outcome variables were tested using partial correlation and principal components analysis (PCA).

RESULTS

Patients on dexamethasone had lower androgens and ACTH but greater insulin resistance compared with those receiving hydrocortisone or prednisolone. Dexamethasone dose and once daily administration were associated with insulin resistance. Partial correlation analysis adjusted for age and sex showed PreDEq weakly correlated (r < 0·2) with blood pressure and androstenedione. Mutation severity was associated with increased PreDEq (F(3,141)  = 4·4, P < 0·01). In PCA, 3 PCs were identified that explained 62% of the total variance (r(2) ) in observed variables. Regression analysis (age and sex adjusted) confirmed that PC2, reflecting disease control (androstenedione, 17-hydroxypregesterone and testosterone), and PC3, reflecting blood pressure and mutations (systolic and diastolic blood pressure and mutation severity), related directly to PreDEq (r(2)  = 23%, P < 0·001).

CONCLUSIONS

In adults with congenital adrenal hyperplasia, dexamethasone use was associated with lower androgens but greater insulin resistance, and increasing glucocorticoid dose associated with increased blood pressure, poor disease control and mutation severity.

The sympathetic nervous system in polycystic ovary syndrome: a novel therapeutic target?

Polycystic ovary syndrome (PCOS) is a common endocrine condition associated with long-term health risks, including type 2 diabetes and vascular dysfunction in addition to reproductive sequelae. Many of the common features of PCOS, such as central obesity, hyperinsulinaemia and obstructive sleep apnoea (OSA), are associated with chronic sympathetic overactivity, suggesting that sympathoexcitation may be involved in the pathogenesis of this condition. Rodent models of polycystic ovaries have shown that ovarian sympathetic outflow may be increased, accompanied by elevated intra-ovarian synthesis of nerve growth factor (NGF) which may be involved in initiation of ovarian pathology. Patients with PCOS have evidence of increased muscle sympathetic nerve activity (MSNA), altered heart rate variability and attenuated heart rate recovery postexercise, compared with age- and BMI-matched controls, suggesting a generalized increase in sympathetic nerve activity. Active weight loss can reduce MSNA and whole body noradrenaline spillover, whereas low-frequency electroacupuncture decreased MSNA in overweight women with PCOS. Treatment of OSA with continuous positive airways pressure may reduce plasma noradrenaline levels and diastolic blood pressure and improve cardiac sympathovagal balance. Renal sympathetic denervation also reduced MSNA, noradrenaline spillover and blood pressure in two PCOS subjects with hypertension, accompanied by improved insulin sensitivity. The sympathetic nervous system may thus offer a new therapeutic target in PCOS but larger and longer-term studies are needed before these treatments can be considered in clinical practice.

How to help the aging male? Current approaches to hypogonadism in primary care

Hypogonadism is a common condition which occurs more frequently in older men. It is characterized by low testosterone (T) and is associated with symptoms which are often nonspecific. A key symptom is low libido, but it can also be associated with erectile dysfunction, reduced muscle mass and strength, increased body fat, reduced bone mineral density and osteoporosis, reduced vitality, and depressed mood. Hypogonadism is linked with a variety of comorbid conditions including erectile dysfunction, metabolic syndrome, diabetes, obesity, and osteoporosis. However, the condition is often underdiagnosed. T supplementation in hypogonadism is associated with a range of benefits including improved sexual function, increased lean body mass and/or reduced fat mass, and improved bone mineral density. A variety of T supplementation formulations are available. Although there is no evidence of increased risk of initiating prostate cancer with T supplementation, it is contraindicated in men with prostate cancer. It is important that primary care physicians are aware of both the signs and symptoms of hypogonadism, the monitoring and testing that is required and the merits and advantages of the various T preparations to ensure optimal management of the condition with a treatment approach that best suits patients' needs.

Evaluation of adverse outcome in young women with polycystic ovary syndrome versus matched, reference controls: a retrospective, observational study

CONTEXT

Polycystic ovary syndrome (PCOS) is associated with insulin resistance, hyperandrogenism, and dyslipidemia, but the effects of these disturbances on long-term health are not fully understood.

AIM

Our aim was to determine the relative risk of type 2 diabetes, cancer, large-vessel disease (LVD), and all-cause mortality for women diagnosed with PCOS.

DESIGN

Data were extracted from the General Practice Research Database, a longitudinal, anonymized research database derived from nearly 600 primary-care practices in the United Kingdom. Patients with a diagnosis of PCOS between 1990 and 2010 were selected. Patients were matched to two sets of controls. The first set was matched according to primary-care practice and age, and the second was also matched on body mass index. Primary outcome was first incident record of diabetes. Crude rates for diabetes were presented, and time to diabetes was analyzed using Cox proportional hazard models. Secondary outcomes (cancer, LVD, and mortality) were also modeled.

RESULTS

Of 53,303 identified with a diagnosis of PCOS, 21,740 (40.8%) met the eligibility criteria. Median follow-up was 4.7 yr (interquartile range = 2.0-8.6 yr) in those with PCOS and 5.8 yr (2.7-9.6) in the reference group. Crude rates of diabetes were 5.7 and 1.7 per 1000 patient-years for cases and controls, respectively. The corresponding adjusted hazard ratio was 3.015 (95% confidence interval = 2.733-3.327). Of cases matched by body mass index, crude rates of diabetes were 4.7 and 2.4 per 1000 patient-years, respectively. The corresponding adjusted hazard ratio was 1.752 (1.514-2.028). No significant difference in BMI-adjusted risk was evident for cancer, LVD, or all-cause mortality.

CONCLUSIONS

During this follow-up period, women with PCOS were not at increased risk of LVD, cancer, or death, but they had increased risk of type 2 diabetes.

Total and free testosterone concentrations are strongly influenced by age and central obesity in men with type 1 and type 2 diabetes but correlate weakly with symptoms of androgen deficiency and diabetes-related quality of life

OBJECTIVE

Testosterone levels are commonly lowered in men with diabetes, but it is unclear how these relate to symptoms of hypogonadism and quality of life. We sought to investigate the relationship between testosterone levels, symptoms of androgen deficiency, erectile function and quality of life in men with type 1 and type 2 diabetes.

DESIGN AND SUBJECTS

Cross-sectional study of 115 men with type 2 diabetes, 93 men with type 1 diabetes and 121 healthy controls.

MEASUREMENTS

Total, bioavailable and free testosterone levels were measured or calculated by Vermuelen's formula. Quality of life and symptom scores were assessed by the Audit of Diabetes Dependent Quality of Life (ADDQoL), androgen deficiency in the aging male (ADAM) and International Index of Erectile Function (IIEF) questionnaires.

RESULTS

Forty-five and sixty-one per cent of men with type 2 diabetes had low total and calculated free testosterone (CFT) levels, respectively. Total testosterone (TT) levels were not lowered in men with type 1 diabetes, but 32% had low CFT. After adjustment for age and waist circumference, only CFT in men with type 2 diabetes (-0·037 nm, 95% CI -0·075 to -0·0003, P = 0.048) remained lowered compared with controls. CFT correlated weakly with ADAM (r = -0·26, 95% CI -0.42 to -0·08, P = 0·006), IIEF (r = 0.19, 95% CI 0.01-0.37, P = 0.042) and ADDQoL (r = 0.21, 95% CI 0·03 to 0·38, P = 0·022) scores in men with type 2, but not type 1 diabetes. Age exerted the predominant effect on erectile function in both groups, in a model incorporating age, testosterone level and complications.

CONCLUSIONS

Testosterone levels are strongly affected by age and central obesity in men with type 1 and type 2 diabetes but correlate weakly with symptoms of androgen deficiency and erectile function. Testosterone levels do not appear to be a major determinant of quality of life in patients with diabetes.

Adipose tissue depot-specific differences in the regulation of hyaluronan production of relevance to Graves' orbitopathy

CONTEXT

Graves' orbitopathy (GO) is associated with Graves' disease, in which anti-TSH receptor (TSHR) autoantibodies (thyroid-stimulating antibodies) increase cAMP causing hyperthyroidism. Excess adipogenesis and hyaluronan (HA) overproduction [HA synthase 2 (HAS2) is the major source] expand the orbital contents causing GO. TSHR activation participates in both processes but an anti-TSHR monoclonal without TSAB activity also increased HA, suggesting the involvement of other cascades. OBJECTIVE AND PATIENTS STUDIED: We investigated using in vitro models in which preadipocytes/fibroblasts from human orbital (n = 12) and sc (n = 10) adipose tissues were treated with IGF-I (to probe the pAkt pathway, recently identified as a positive regulator of HAS2), TSH, and/or various inhibitors. Changes in HA during in vitro-induced adipogenesis were also evaluated.

MAIN OUTCOME AND RESULTS

Adipogenesis in orbital preadipocytes was accompanied by significantly increased HAS2 transcripts and HA accumulation in contrast to sc cells in which differentiation significantly decreased HAS2 mRNA and secreted HA. Surprisingly, IGF-I alone did not increase HAS2 levels, despite significantly increasing the ratio of phosphorylated to total Akt; furthermore, an Akt inhibitor increased orbital (but not sc) HAS2 transcripts. A stimulatory effect of IGF-I on HAS2 transcripts was revealed by addition of rapamycin in sc but by a MAPK kinase inhibitor in orbital fibroblasts.

CONCLUSIONS

The results have several possible explanations including a phosphorylation-dependent repressor of HAS2 transcript accumulation, exclusively in the orbit. The difference in control of HAS2 expression allows the activation of one of the mechanisms underlying GO, adipogenesis, to be linked biologically with the second, HA overproduction.

Endocrine oncology in pregnancy

Endocrine tumours occur rarely in pregnant women but present clinicians with unique challenges. A high index of suspicion is often required to make a diagnosis since the symptoms and signs associated with many of these tumours, including insulinoma, adrenocortical carcinoma and phaeochromocytoma, mimic those of normal pregnancy or its complications, such as pre-eclampsia. The evidence base which informs management is very limited hence decisions on investigation and therapy must be individualised and undertaken jointly by the multidisciplinary medical team and the patient. The optimal strategy will depend on the nature and stage of the endocrine tumour, gestational stage, treatments available and patient wishes. Thus, surgical intervention, appropriately timed, may be considered in pregnancy for resectable adrenocortical carcinoma or phaeochromocytoma, but delayed until the postpartum period for well-differentiated thyroid cancer. Medical therapy may be required to reduce the drive to tumour growth, control symptoms of hormone excess and to minimise the risks of surgery, anaesthesia or labour.

Adenosine A2A and A2B receptor expression in neuroendocrine tumours: potential targets for therapy

The clinical management of neuroendocrine tumours is complex. Such tumours are highly vascular suggesting tumour-related angiogenesis. Adenosine, released during cellular stress, damage and hypoxia, is a major regulator of angiogenesis. Herein, we describe the expression and function of adenosine receptors (A(1), A(2A), A(2B) and A(3)) in neuroendocrine tumours. Expression of adenosine receptors was investigated in archival human neuroendocrine tumour sections and in two human tumour cell lines, BON-1 (pancreatic) and KRJ-I (intestinal). Their function, with respect to growth and chromogranin A secretion was carried out in vitro. Immunocytochemical data showed that A(2A) and A(2B) receptors were strongly expressed in 15/15 and 13/18 archival tumour sections. Staining for A(1) (4/18) and A(3) (6/18) receptors was either very weak or absent. In vitro data showed that adenosine stimulated a three- to fourfold increase in cAMP levels in BON-1 and KRJ-1 cells. The non-selective adenosine receptor agonist (adenosine-5'N-ethylcarboxamide, NECA) and the A(2A)R agonist (CGS21680) stimulated cell proliferation by up to 20-40% which was attenuated by A(2B) (PSB603 and MRS1754) and A(2A) (SCH442416) receptor selective antagonists but not by the A(1) receptor antagonist (PSB36). Adenosine and NECA stimulated a twofold increase in chromogranin A secretion in BON-1 cells. Our data suggest that neuroendocrine tumours predominantly express A(2A) and A(2B) adenosine receptors; their activation leads to increased proliferation and secretion of chromogranin A. Targeting adenosine signal pathways, specifically inhibition of A(2) receptors, may thus be a useful addition to the therapeutic management of neuroendocrine tumours.

Brown fat and obesity: the next big thing?

Brown adipose tissue (BAT) is well recognised to have an important role in the maintenance of body temperature in animals and human neonates, its thermogenic action affected by a tissue-specific uncoupling protein; fatty acid oxidation within the numerous brown adipocyte mitochondria is rendered inefficient leading to heat, rather than adenosine triphosphate (ATP), production. BAT was believed to show rapid involution in early childhood, leaving only vestigial amounts in adults. However, recent evidence suggests that its expression in adults is far more common than previously appreciated, with a higher likelihood of detection in women and leaner individuals. It is conceivable that BAT activity might reduce the risk of developing obesity since fat stores are used for thermogenesis, and a directed enhancement of adipocyte metabolism might have value in weight reduction. However, it is as yet unclear how such manipulation of BAT might be achieved; even in animal models, the control of thermogenic activity is incompletely understood. Even so, there is still much to interest the endocrinologist in BAT, with a range of hormones affecting adipocyte activity. This may either contribute to normal physiological function, or the phenotypical presentation of states of pathological hormone excess or deficiency. Thus, the gender differences in BAT distribution may be attributable to the differential effects of male and female sex hormones, whilst BAT expansion may drive the weight loss associated with catecholamine-producing phaeochromocytomas. These observations support an important influence of the endocrine system on BAT activity and offer new potential targets in the treatment of obesity.

Health status of adults with congenital adrenal hyperplasia: a cohort study of 203 patients

CONTEXT

No consensus exists for management of adults with congenital adrenal hyperplasia (CAH) due to a paucity of data from cohorts of meaningful size.

OBJECTIVE

Our objective was to establish the health status of adults with CAH.

DESIGN AND SETTING

We conducted a prospective cross-sectional study of adults with CAH attending specialized endocrine centers across the United Kingdom.

PATIENTS

Participants included 203 CAH patients (199 with 21-hydroxylase deficiency): 138 women, 65 men, median age 34 (range 18-69) years.

MAIN OUTCOME MEASURES

Anthropometric, metabolic, and subjective health status was evaluated. Anthropometric measurements were compared with Health Survey for England data, and psychometric data were compared with appropriate reference cohorts.

RESULTS

Glucocorticoid treatment consisted of hydrocortisone (26%), prednisolone (43%), dexamethasone (19%), or a combination (10%), with reverse circadian administration in 41% of patients. Control of androgens was highly variable with a normal serum androstenedione found in only 36% of patients, whereas 38% had suppressed levels suggesting glucocorticoid overtreatment. In comparison with Health Survey for England participants, CAH patients were significantly shorter and had a higher body mass index, and women with classic CAH had increased diastolic blood pressure. Metabolic abnormalities were common, including obesity (41%), hypercholesterolemia (46%), insulin resistance (29%), osteopenia (40%), and osteoporosis (7%). Subjective health status was significantly impaired and fertility compromised.

CONCLUSIONS

Currently, a minority of adult United Kingdom CAH patients appear to be under endocrine specialist care. In the patients studied, glucocorticoid replacement was generally nonphysiological, and androgen levels were poorly controlled. This was associated with an adverse metabolic profile and impaired fertility and quality of life. Improvements in the clinical management of adults with CAH are required.

Reduced total testosterone concentrations in young healthy South Asian men are partly explained by increased insulin resistance but not by altered adiposity

OBJECTIVE

To compare ethnic differences in total, free and bioavailable testosterone amongst young healthy South Asian and Caucasian men.

DESIGN AND SUBJECTS

Cross-sectional study of 134 healthy men (age 20-40 years) of South Asian (n = 67) or Caucasian (n = 67) origin, recruited from hospital staff and students working in Newport, UK. Subjects were excluded if they had a fasting plasma glucose >5.9 mmol/l, central obesity [waist circumference ≥ 94 cm (Caucasian) or ≥ 90 cm (South Asian)] or significant other disease.

MEASUREMENTS

Fasting plasma glucose, total testosterone (determined by immunoassay and mass spectrometry), albumin, sex hormone-binding globulin (SHBG) and insulin were measured. Free and bioavailable testosterone were calculated using Vermeulen's formula, and insulin resistance was estimated by HOMA-IR.

RESULTS

The South Asians were slightly older (P = 0.04), shorter (P < 0.001), lighter (P < 0.001), more insulin resistant (P = 0.006), and had a lower body mass index BMI (P = 0.012), waist circumference (P = 0.043) and SHBG (P = 0.001) than the Caucasians. Total testosterone was significantly lower in South Asians (mass spectrometry: geometric mean 16.3 nmol/l; 95% reference interval 9.3-28.6 nmol/l) compared with Caucasians (mass spectrometry: geometric mean 18.4 nmol/l; 95% reference interval 10.6-31.9 nmol/l; P = 0.015), but calculated free and bioavailable testosterone were not different between groups. Adjusting for HOMA-IR, but not BMI or waist circumference, partly attenuated the differences in total testosterone.

CONCLUSIONS

Total, but not free, testosterone concentrations are lower in healthy South Asian men than in Caucasians. These differences are apparent at a young age and may be partly attributable to alterations in insulin sensitivity.

Dehydroepiandrosterone (DHEA) treatment in vitro inhibits adipogenesis in human omental but not subcutaneous adipose tissue

Dehydroepiandrosterone (DHEA), a precursor sex steroid, circulates in sulphated form (DHEAS). Serum DHEAS concentrations are inversely correlated with metabolic syndrome components and in vivo/in vitro studies suggest a role in modulating adipose mass. To investigate further, we assessed the in vitro biological effect of DHEA in white (3T3-L1) and brown (PAZ6) preadipocyte cell lines and human primary preadipocytes. DHEA (from 10(-8)M) caused concentration-dependent proliferation inhibition of 3T3-L1 and PAZ6 preadipocytes. Cell cycle analysis demonstrated unaltered apoptosis but indicated blockade at G1/S or G2/M in 3T3-L1 and PAZ6, respectively. Preadipocyte cell-line adipogenesis was not affected. In human primary subcutaneous and omental preadipocytes, DHEA significantly inhibited proliferation from 10(-8)M. DHEA 10(-7)M had opposing effects on adipogenesis in the two fat depots. Subcutaneous preadipocyte differentiation was unaffected or increased whereas omental preadipocytes showed significantly reduced adipogenesis. We conclude that DHEA exerts fat depot-specific differences which modulate body composition by limiting omental fat production.

Adenosine regulates thrombomodulin and endothelial protein C receptor expression in folliculostellate cells of the pituitary gland

Adenosine stimulates the release of interleukin 6 (IL-6) and vascular endothelial growth factor from folliculostellate cells of the anterior pituitary gland indicating that such cells are also involved in the communication between the immune and endocrine systems during stress and inflammation. In order to understand the precise actions of adenosine on folliculostellate cells, DNA microarray analysis was used to determine global changes in gene expression. Hierarchical clusters revealed, of the genes that had altered expression, the majority were suppressed and many, such as B cell translocation gene 2 and cyclin-dependent kinase inhibitor 2b were related to cell cycle arrest or inhibition of proliferation. Several of the up-regulated genes were associated with cytokine signalling or membrane receptor activity. The most notable of these being IL-6, sulfiredoxin 1, endothelial protein C receptor (EPCR) and thrombomodulin (THBD) which can all play a role in controlling inflammation. The EPCR and THBD pathway is well known in anti-coagulation but also has anti-inflammatory and anti-apoptotic properties. Up-regulation of EPCR and THBD in folliculostellate cells was confirmed by qRT-PCR and western blotting analysis and their expression were also demonstrated in many of the hormone-secreting cells of the anterior pituitary gland. Our findings suggest that adenosine can stimulate expression of stress and inflammation related genes from folliculostellate cells of the anterior pituitary gland. These genes include EPCR and THBD, neither of which has been previously identified in the pituitary gland.

Metformin reduces arterial stiffness and improves endothelial function in young women with polycystic ovary syndrome: a randomized, placebo-controlled, crossover trial

CONTEXT

Patients with polycystic ovary syndrome (PCOS) have an increased prevalence of insulin resistance and display subclinical evidence of early cardiovascular disease. Metformin improves insulin sensitivity and circulating markers of cardiovascular risk in patients with PCOS, but it is unclear whether this translates into improvements in vascular function.

OBJECTIVE

Our objective was to evaluate the effects of metformin on arterial stiffness and endothelial function in women with PCOS.

DESIGN AND INTERVENTION

Thirty women with PCOS were assigned to consecutive 12-wk treatment periods of metformin or placebo in a randomized, double-blind, crossover design separated by an 8-wk washout.

MAIN OUTCOME MEASURES

The primary outcome measures were assessments of arterial stiffness [augmentation index (AIx), central blood pressure, and brachial and aortic pulse wave velocity (PWV)] and endothelial function. Anthropometry, testosterone, and metabolic biochemistry (lipids, homeostasis model of assessment for insulin resistance, high-sensitivity C-reactive protein, adiponectin, and plasminogen activator inhibitor-1) were also assessed.

RESULTS

Metformin improved AIx [-6.1%; 95% confidence interval (CI) for the difference -8.5 to -3.5%; P < 0.001], aortic PWV (-0.76 m/sec; 95% CI for the difference -1.12 to -0.4 m/sec; P < 0.001), brachial PWV (-0.73 m/sec; 95% CI for the difference -1.09 to -0.38; P < 0.001), central blood pressure (P < 0.001), and endothelium-dependent (AIx after albuterol; P = 0.003) and endothelium-independent (AIx after nitroglycerin; P < 0.001) vascular responses. Metformin also reduced weight (P < 0.001), waist circumference (P < 0.001), and triglycerides (P = 0.004) and increased adiponectin (P = 0.001) but did not affect testosterone or other metabolic measures.

CONCLUSIONS

Short-term metformin therapy improves arterial stiffness and endothelial function in young women with PCOS.

TSH receptor activation and body composition

The impacts of hyper and hypothyroidism on body composition, i.e. the relative quantity and quality of bone, adipose tissue and muscle, have traditionally been attributed uniquely to abnormal levels of free thyroid hormones. The presence of biologically active TSH receptors in bone, fat and muscle, raises the possibility that both thyroid hormones and TSH contribute to the changes in body composition associated with thyroid disease. This review evaluates the evidence for this in terms of the in vitro experimental approaches applied, data from in vivo sources (i.e. mouse models) and patient-based studies.

Effects of dehydroepiandrosterone replacement on vascular function in primary and secondary adrenal insufficiency: a randomized crossover trial

CONTEXT

Patients with Addison's disease and hypopituitarism have increased mortality, chiefly related to vascular disease. Both diseases are characterized by dehydroepiandrosterone (DHEA) deficiency, yet this is not usually corrected. It is unclear whether treatment of these conditions with DHEA improves cardiovascular risk.

OBJECTIVE

The aim of the study was to evaluate the effects of DHEA on arterial stiffness and endothelial function in subjects with Addison's disease and hypopituitarism.

DESIGN AND INTERVENTION

Forty subjects (20 with Addison's disease, 20 with panhypopituitarism) were assigned to consecutive 12-wk treatment periods of DHEA 50 mg or placebo in a randomized, double-blind, crossover design separated by an 8-wk washout.

MAIN OUTCOME MEASURES

Primary outcome parameters were measures of arterial stiffness [augmentation index, central blood pressure, brachial and aortic pulse wave velocity (PWV)] and endothelial function. Serum androgens, anthropometry, and metabolic biochemistry (lipids, homeostasis model of assessment for insulin resistance, high sensitivity C-reactive protein, adiponectin, plasminogen activator inhibitor-1) were also assessed.

RESULTS

Despite normalization of DHEA sulfate, androstenedione, and testosterone (females), DHEA replacement did not affect augmentation index, aortic PWV, brachial PWV, central blood pressure, or endothelial function. DHEA did not affect any anthropometric or metabolic measures, apart from a small reduction in high-density lipoprotein cholesterol (-0.08 mmol/liter; P = 0.007; 95% confidence interval for the difference, -0.13 to -0.02 mmol/liter).

CONCLUSIONS

Short-term DHEA supplementation does not significantly affect measures of arterial stiffness or endothelial function in patients with adrenal insufficiency.

Can abdominal bioelectrical impedance refine the determination of visceral fat from waist circumference?

Ryo et al (2005 Diabetes Care 28 451-3) reported a new method for measuring the visceral fat area (VFA) by combining abdominal bioelectrical impedance analysis (BIA) with measurement of waist circumference (WC), but very few methodological details were provided. Furthermore, the study did not test the use of WC alone as an indicator of VFA even though others had previously reported a strong correlation. We sought to determine the optimal measurement technique and analysis for measuring VFA by abdominal BIA and WC. 18 volunteers (age 23-64 years) underwent measurement of WC, abdominal impedance (Bodystat 500 four-electrode system) and a single cross-sectional CT scan at the umbilicus. VFA derived using WC(3) and measurements of abdominal impedance from electrode pairs sited at the flank predicted the value of VFA measured by CT with correlation r = 0.904 (p < 0.0001); the optimizing power of WC was 3.3 (r = 0.905). However, the use of WC(1.9) alone, without involving BIA at all, provided a similar correlation (r = 0.923). Our small preliminary study shows that abdominal BIA is potentially a practicable non-invasive technique for measurement of VFA but casts doubt on whether it adds any value to the use of WC alone. Larger studies are now required to test this finding.

The adenosine a2b receptor: its role in inflammation

Investigations into the role of the adenosine A2b receptor have been enigmatic due to the lack of good selective high affinity agonists and antagonists. Over the last few years several new antagonist compounds, based either on a xanthine or pyrrolpyrimidine (polyheterocyclic) structure have been designed and these have been used to localise A2b receptors in different tissues and to determine their function. Recently, animals harbouring either a loss or an over-expression of the A2b receptor have been created and these suggest an anti-inflammatory role for the receptor. In this short review, we describe how the A2b receptor influences inflammation in different tissues. In the anterior pituitary gland the A2b receptors exist predominantly in folliculostellate cells where it stimulates secretion of IL-6 and VEGF and influences gap-junctional communication via connexin-43. The A2b receptor also mediates the release of pro-inflammatory cytokines from many tissues such as bronchial smooth muscle, intestinal epithelial cells and mast cells. The presence of a HIF-1alpha binding site in the promoter region of the A2b receptor gene shows that it is strongly implicated in hypoxia and angiogenesis. Targeting the A2b receptor may also be useful in combating autoimmune type I diabetes. These findings, together, indicate that the A2b receptor plays a role in inflammation; its precise action, whether pro- or anti-inflammatory however may be cell type dependent. Nevertheless several A2b receptor antagonists are being developed for therapeutic intervention and these are either at the preclinical stage or in phase I clinical trials as is the case for CVT-6883 for asthma.

Growth hormone (GH1) gene variation and the growth hormone receptor (GHR) exon 3 deletion polymorphism in a West-African population

Among Europeans, functionally significant GH1 gene variants occur not only in individuals with idiopathic growth hormone (GH) deficiency and/or short stature but also fairly frequently in the general population. To assess the generality of these findings, 163 individuals from Benin, West Africa were screened for mutations and polymorphisms in their GH1 genes. A total of 37 different sequence variants were identified in the GH1 gene region, 24 of which occurred with a frequency of >1%. Although four of these variants were novel missense substitutions (Ala13Val, Arg19His, Phe25Tyr and Ser95Arg), none of these had any measurable effect on either GH function or secretion in vitro. Some 37 different GH1 promoter haplotypes were identified, 23 of which are as yet unreported in Europeans. The mean in vitro expression level of the GH1 promoter haplotypes observed in the African population was significantly higher than that previously measured in Britons (p<0.001). A gene conversion in the GH1 promoter, previously reported in a single individual of British origin, was found to occur at polymorphic frequency (5%) in the West-African population and was associated with a 1.7-fold increase in promoter activity relative to the wild-type. The d3 allele of the GHR exon 3 deletion polymorphism, known to be associated with increased GH responsiveness, was also found to occur at an elevated frequency in these individuals from Benin. We speculate that both elevated GH1 gene expression and increased GHR-mediated GH responsiveness may constitute adaptive responses to the effects of scarce food supply in this West-African population since increased circulating GH appears to form part of a physiological response to nutritional deprivation.

Adenosine stimulates connexin 43 expression and gap junctional communication in pituitary folliculostellate cells

Adenosine is known to stimulate interleukin (IL)-6 and vascular endothelial growth factor (VEGF) secretion from pituitary TtT/GF folliculostellate [corrected] (FS) cells indicating that it is an important paracrine regulator of anterior pituitary function. This study demonstrates that rodent anterior pituitary cell lines produce extracellular adenosine that is able to increase intercellular gap junction communication in FS cells. Ecto-5'-nucleotidase (CD73), the enzyme that generates adenosine from AMP, was demonstrated by immunocytochemistry in approximately 20% of anterior pituitary cells, and some of these cells colocalized with prolactin and growth hormone. CD73 mRNA and protein were detected in GH3 and MMQ (somatotroph-lactotroph lineages) and TtT/GF cells, and enzyme activity was demonstrated by the conversion of exogenously added fluorescent ethenoAMP to ethenoadenosine. Adenosine production, as measured by HPLC, was detected in GH3 (1 microM/h) and MMQ (3 microM/h) but not in TtT/GF cells. Adenosine (EC50: 0.5 microM) and NECA (universal adenosine receptor agonist; EC50 0.1 microM) stimulated connexin 43 (Cx43) mRNA and protein expression within 1-2 h in TtT/GF cells. Adenosine and NECA also stimulated gap junctional intercellular communication (as assessed by transmission of Alexa Fluor 488) by 6- to 8-fold in comparison with untreated TtT/GF cells. In cocultures of MMQ and TtT/GF cells, Cx43 expression in TtT/GF cells increased in proportion to the number of MMQ cells plated out. These data suggest that adenosine, formed locally in the anterior pituitary gland can stimulate gap junction communication in FS cells.

Increasing thyroxine requirements in primary hypothyroidism: don't forget the urinalysis!

Rising thyroid stimulating hormone (TSH) levels in patients being treated for primary hypothyroidism usually indicate poor compliance with thyroxine therapy. In rare instances, drugs or diseases affecting absorption of thyroxine or drugs that accelerate thyroxine metabolism can manifest in a similar fashion. Nephrotic syndrome is a rare cause of such a presentation though its presence can rapidly be suspected by dipstick urine testing. In this report we describe a patient with long-standing primary thyroid failure whose thyroxine dose requirements increased upon development of massive proteinuria. Biochemical testing and renal biopsy subsequently demonstrated nephrotic syndrome and amyloid deposition in association with myeloma. Dipstick urine testing should be considered in all hypothyroid patients with rising TSH levels, where good compliance with thyroxine therapy is likely.

Genetic variation at the growth hormone (GH1) and growth hormone receptor (GHR) loci as a risk factor for hypertension and stroke

An increased prevalence of both hypertension and cerebrovascular stroke is apparent in growth hormone (GH) deficiency whilst hypertension is a frequent complication in acromegaly. This has suggested a possible link between GH, stature and arterial function. Since the risk of both hypertension and stroke also appears to be inversely correlated with adult height, we have instigated an exploratory study to assess whether inter-individual variation in the genes encoding human growth hormone (GH1) and the GH receptor (GHR) might be associated with an increased risk of hypertension and stroke. GH1 promoter haplotypes were found to differ significantly not only between hypertensive patients (n = 111) and controls (n = 121) but also between stroke patients (n = 155) and controls (n = 158). Intriguingly, the association between GH1 promoter haplotype and risk of hypertension was much greater in females than in males. An inverse correlation between height and central systolic blood pressure was apparent in both hypertensive patients and normal controls but was much stronger in individuals carrying at least one GH1 promoter risk haplotype. The GH1 genotype therefore constitutes a risk factor for hypertension that interacts with stature. A strong association was found between the presence of at least one GH1 risk haplotype and a family history of stroke at an early age (odds ratio: 9.07, 95% confidence interval: 1.14-72.22). Three novel GH variants (Arg16His, Phe176Cys, Cys189Arg) were identified during the course of this study. Although two exhibited markedly reduced biological activity in vitro, their clinical significance remains unclear. No association was found between GHR genotype and either hypertension or stroke, nor was any interaction noted between GHR and GH1 genotypes in terms of a disease association. However, an association between GHRd3 genotype and hypertension was observed among stroke patients, particularly females. Elevated HDL was found to be a risk factor for hypertension in individuals lacking a copy of the GHRd3 allele. Weak associations with GHR genotype were also noted for peripheral systolic and diastolic blood pressure in hypertensive patients. Although the underlying mechanisms are still unclear, our findings are consistent with a complex relationship between height, hypertension, GH1 promoter haplotype, GHR polymorphism and the risk of stroke.

Long-term remission following withdrawal of dopamine agonist therapy in subjects with microprolactinomas

OBJECTIVE

Reports suggest that up to 70% of patients with microprolactinomas treated with dopamine agonist therapy may achieve long-term normoprolactinaemic remission following drug withdrawal. Yet, there is no consensus on the duration of therapy nor is therapeutic interruption universally practised. We have assessed remission rates in a large cohort of treatment-naive subjects with microprolactinomas. Subjects received dopamine agonist (DA) therapy with either cabergoline or bromocriptine for a period of 2 to 3 years in the majority of cases, followed by a trial of treatment withdrawal.

DESIGN

Retrospective analysis of clinic records of 89 patients (mean age 32.7 +/- 8.4 years, 84 women and 5 men) who had received either cabergoline (n = 67) (0.5-3 mg weekly) or bromocriptine (n = 22) (2.5-10 mg daily) for a mean duration of 3.1 years.

RESULTS

Following withdrawal of therapy, 57 subjects developed recurrence (64%) and the mean time to recurrence was 9.6 months (range 1-44 months), while 32 subjects (36%) remained in remission beyond 1 year (mean 3.6 years, range 1-7 years). There was no difference in remission rates between subjects treated with cabergoline (n = 21) and bromocriptine (n = 11), but a direct relationship between pretreatment prolactin concentration and risk of recurrent symptomatic hyperprolactinaemia was observed. No subjects developed clinical features to suggest tumour expansion following therapeutic discontinuation.

CONCLUSIONS

This study confirms that abrupt withdrawal of chronic dopamine agonist therapy, following 2 to 3 years of treatment is safe and associated with long-term remission in 30-40% of subjects with microprolactinomas. This therapeutic strategy is convenient and applicable in clinical practice.

Animal models of diabetes mellitus

Animal models have been used extensively in diabetes research. Early studies used pancreatectomised dogs to confirm the central role of the pancreas in glucose homeostasis, culminating in the discovery and purification of insulin. Today, animal experimentation is contentious and subject to legal and ethical restrictions that vary throughout the world. Most experiments are carried out on rodents, although some studies are still performed on larger animals. Several toxins, including streptozotocin and alloxan, induce hyperglycaemia in rats and mice. Selective inbreeding has produced several strains of animal that are considered reasonable models of Type 1 diabetes, Type 2 diabetes and related phenotypes such as obesity and insulin resistance. Apart from their use in studying the pathogenesis of the disease and its complications, all new treatments for diabetes, including islet cell transplantation and preventative strategies, are initially investigated in animals. In recent years, molecular biological techniques have produced a large number of new animal models for the study of diabetes, including knock-in, generalized knock-out and tissue-specific knockout mice.

Azoospermia in testicular sarcoidosis is an indication for corticosteroid therapy

OBJECTIVE

To report improvement of azoospermia and hypogonadism after high-dose corticosteroid therapy in a patient with testicular sarcoidosis.

DESIGN

Case report.

SETTING

University hospital.

PATIENT(S)

A 27-year-old man with testicular sarcoidosis and azoospermia.

INTERVENTION(S)

High-dose corticosteroid therapy was commenced in an attempt to improve sperm count and restore gonadal function.

MAIN OUTCOME MEASURE(S)

Analysis of sperm count, T, and gonadotropin response to steroid therapy.

RESULT(S)

FSH and LH concentrations decreased and T levels increased in parallel with control of disease activity with steroid therapy. Repeat semen analysis demonstrated a significant increase in sperm count, allowing sperm banking to take place.

CONCLUSION(S)

High-dose corticosteroid therapy may be indicated in testicular sarcoidosis, not only for control of systemic disease activity but also for recovery of gonadal function and spermatogenesis.

Adenosine-induced IL-6 expression in pituitary folliculostellate cells is mediated via A2b adenosine receptors coupled to PKC and p38 MAPK

Activation of adenosine receptors in folliculostellate (FS) cells of the pituitary gland leads to the secretion of IL-6 and vascular endothelial growth factor (VEGF). We investigated the action of adenosine A2 receptor agonists on IL-6 and VEGF secretion in two murine FS cell lines (TtT/GF and Tpit/F1), and demonstrated a rank order of potency, 5'-N-ethylcarboxamidoadenosine (NECA)>2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine>adenosine, suggesting mediation via the A2b receptor. NECA-mediated IL-6 release was inhibited by the PLC inhibitor 1-[6-((17beta-3-methoxyestra-1,3,5(10)-tiene-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione, the PI3 kinase inhibitor wortmannin and the PKC inhibitors bisindolylmaleimide 1 and bisindolymaleimide X1 HCl (Ro-32-0432). NECA-mediated IL-6 release was attenuated (<50%) by the extracellular signal-regulated kinase MAPK inhibitor 2'-amino-3'-methoxyflavone, and completely (>95%) inhibited by the p38 MAPK inhibitor 4-(4-fluorophenyl)-2-(4-methylsulphinylphenyl)-5-(4-pyridyl)1H-imidazole. NECA stimulates p38 MAPK phosphorylation that is inhibited by Ro-32-0432 but not by wortmannin. Dexamethasone inhibits NECA-stimulated IL-6 and VEGF secretion. These findings indicate that adenosine can stimulate IL-6 secretion in FS cells via the A2b receptor coupled principally to PLC/PKC and p38 MAPK; such an action may be important in the modulation of inflammatory response processes in the pituitary gland.

Transsphenoidal surgery for acromegaly in wales: results based on stringent criteria of remission

We retrospectively analyzed 90 patients who underwent transsphenoidal surgery (performed by three surgeons) in our center as initial therapy for acromegaly. We used a combination of modern, evidence-based remission criteria including mean day curve GH less than 2.5 micro g/liter (5 mU/liter), a nadir GH less than 1.0 micro g/liter (2 mU/liter) after an oral glucose tolerance test, and normal age-related IGF-I levels (where available). Fifty-seven of 90 (63%) patients remained in remission after surgery. Seventy-nine percent of patients with microadenomas but only 56% of patients with macroadenomas achieved remission (P < 0.001). Eighty-six percent of patients with preoperative GH levels below 10 micro g/liter (day profile or after oral glucose tolerance test) went into remission, compared with 51% of patients with GH levels above 25 micro g/liter at diagnosis (P < 0.002). The remission rate was also related to the period of surgery that was significantly higher in 1998-2001 (76%; P < 0.05) compared with 1990-1997 (54%) and 1980-1989 (63%). There were no recurrences or perioperative deaths. Meningitis occurred in 3% of patients, cerebrospinal fluid rhinorrhea in 7%, and permanent diabetes insipidus in 15%. The proportion of patients who developed new anterior pituitary hormone deficiencies and panhypopituitarism was significantly less in the period 1998-2001 (P < 0.001) when compared with the periods from 1990-1997 and 1980-1989. Transsphenoidal surgery is a safe and effective treatment for acromegaly, and our results compare favorably with those from published series. The presence of an intrasellar lesion and low preoperative GH levels is a good predictor of remission in the long term, but historically in our center this can only be achieved in a significant proportion of patients at the expense of some degree of hypopituitarism. However, surgical outcome in our center, including a reduced frequency of hypopituitarism, has improved significantly over time, coincident with the arrival of a dedicated pituitary neurosurgeon and the use of selective adenomectomy as the preferred surgical approach wherever possible.

Adenosine signalling pathways in the pituitary gland: one ligand, multiple receptors

Adenosine receptors are widely distributed in most species and mediate a diverse range of physiological and pathological effects. Although adenosine receptors have been identified in the pituitary gland, the distribution of the individual subtypes (A(1), A(2A), A(2B), A(3)) has not been well defined. Furthermore, the effects of adenosine on pituitary trophic activity and function are not well established despite good evidence for growth- and immune-modulating properties of the nucleoside elsewhere. Recent advances have provided a more detailed description of adenosine receptor distribution and function in the anterior pituitary and this commentary reviews these observations and highlights some of the possible implications in relation to the control of the hypothalamic-pituitary-adrenal axis and the regulation of inflammation and pituitary cell growth.

Novel insights into how purines regulate pituitary cell function

Purine nucleosides and nucleotides are widely distributed substances that exhibit a diverse range of effects in a number of tissues, acting as important extracellular signalling molecules in addition to their more established roles in cellular metabolism. They mediate their effects via activation of distinct cell surface receptors, termed adenosine (or P1) and P2 purinergic receptors. Although roles for adenosine and adenine nucleotides have been described previously in the pituitary gland, the distribution of the receptor subtypes and the effects of their activation on pituitary function are not well defined. Recent evidence, however, has emerged to describe a complex signalling system for purines in the pituitary gland. Data from a variety of studies have shown that the expression pattern, number and affinity of adenosine and/or P2 receptors may be cell-type specific and that non-endocrine in addition to endocrine cells elaborate these receptors. These variations, along with the diverse range of signalling pathways activated, dictate the response of individual cell types to extracellular purines, with roles now emerging for these substances in the regulation of hormone release, pituitary cell proliferation and cytokine/growth factor expression. In this review, we discuss these advances and examine some implications for pituitary growth control and the response of the hypothalamic-pituitary-adrenal axis to stress and inflammation.

Adenosine-regulated cell proliferation in pituitary folliculostellate and endocrine cells: differential roles for the A(1) and A(2B) adenosine receptors

A(1) and A(2) adenosine receptors have been identified in the pituitary gland, but the cell type(s) on which they are located and their effects on pituitary cell growth are not known. Therefore, we analyzed the expression of A(1) and A(2) receptors in primary rat anterior pituitary cells, two pituitary folliculostellate (TtT/GF and Tpit/F1) and two pituitary endocrine (GH(3) and AtT20) cell lines, and compared their effects on cell proliferation. In anterior pituitary and folliculostellate cells, adenosine and adenosine receptor agonists (5'-N-ethylcarboxamidoadenosine, a universal agonist, and CGS 21680, an A(2A) receptor agonist) stimulated cAMP levels with a rank order of potency that indicates the presence of functional A(2B) receptors. This stimulation, however, was not observed in either GH(3) or AtT20 cells, where adenosine and the A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine inhibited VIP/forskolin-stimulated cAMP production. Expression of A(2B) and A(1) receptors in the folliculostellate cells and that of the A(1) receptor in the endocrine cells were confirmed by RT-PCR, immunocytochemistry, and ligand binding. Adenosine and 5'-N-ethylcarboxamidoadenosine dose-dependently (10 nM to 10 microM) stimulated growth in the folliculostellate, but not in the endocrine, cells, whereas in the latter, 100 microM adenosine and 2-chloro-N(6)-cyclopentyladenosine inhibited cell proliferation by slowing cell cycle progression. These data highlight the differential expression of A(1) and A(2B) adenosine receptors in pituitary cells and provide evidence for opposing effects of adenosine on pituitary folliculostellate and endocrine cell growth.

Mitogen-activated protein kinase mediates epidermal growth factor-induced morphogenesis in pituitary GH3 cells

Epidermal growth factor (EGF) causes pituitary GH3 cells to change from their normal predominantly rounded morphology to much more elongated cells with extensive filopodia, and this effect is accompanied by a parallel increase in cell volume. In view of this, and because EGF receptor expression is increased in some pituitary tumours, we examined the mechanism of this EGF-induced morphological effect as it may play a role in tumour invasiveness. The effect of treatment of the cells with EGF (1 nm, 4 days) was determined visually (expressed as percent non round cells) and by measuring the cell volume by Coulter Counter analysis. EGF treatment caused the cells to change their morphology with percent non round cells increasing from 37% in control cells to 74% in EGF-treated cultures; this was accompanied by a parallel increase in cell volume. Treatment of the cells with EGF in the presence of the MEK1 inhibitor (PD98059) completely blocked the EGF-induced morphological changes, showing that activation of the mitogen-activated protein kinase (MAPK) pathway is necessary to mediate this effect. Transfection of the cells with a constitutively activated mutant of MEK1 produced a similar morphological change to that produced by EGF treatment, with the proportion of non round cells increasing to 62% with a parallel increase in cell volume compared to cells transfected with the empty vector, demonstrating that direct activation of MAPK pathway is sufficient to mediate the observed morphological effects. The effects produced by activated MEK1 transfection could be blocked by PD98059. EGF had opposing effects on prolactin and growth hormone (GH) secretion by the cells, increasing prolactin release and inhibiting GH release. Transfection of the cells with activated MEK1 produced similar effects on hormone release as EGF treatment. In conclusion, the morphological effects of EGF on GH3 cells are mediated by activation of the MAPK pathway as blockade of this pathway abolished the observed effect, and direct activation of this pathway by transfection with an activated mutant of MEK1 was able to duplicate these effects. This mechanism may contribute to the growth and possibly local invasiveness of some pituitary tumours that express the EGF receptor.

Long-term follow-up results of transsphenoidal surgery for Cushing's disease in a single centre using strict criteria for remission

OBJECTIVE

Transsphenoidal selective adenomectomy (TSA) is widely accepted as the treatment of choice for Cushing's disease but not all patients are cured by this procedure. The success of surgery depends on the skill and experience of the surgeon but the criteria used to define remission are highly variable. We have analysed the outcome following surgery in our centre using the stringent requirement of a postoperative serum cortisol of < 50 nmol/l as our definition of remission and assessed whether changes in surgical policy, including a greater emphasis on selective procedures and the move in recent years to a single surgeon undertaking all pituitary surgery, have improved complication and remission rates.

PATIENTS AND METHODS

The case notes, histology and pituitary imaging of 54 consecutive patients (42 females, mean age 41 years) with pituitary-dependent Cushing's syndrome who had undergone transsphenoidal surgery between January 1980 and November 2000 were reviewed. Follow-up was for a median of 6 years (range 6 months to 21 years).

RESULTS

One patient died within 1 week of surgery (1.9%) and major morbidity occurred in eight patients (15%). Clinical and biochemical remission was achieved in 41 patients (77%) with only two recurrences (5%) to date. Success was related to tumour size with 37 (86%) of 43 intrasellar lesions successfully resected compared with only four (40%) of 10 extrasellar adenomas. Twenty-four (59%) of those in remission developed partial or complete hypopituitarism compared with four (33%) of those not in remission. The extent of surgical exploration predicted the development of hypopituitarism (88% total hypophysectomy, 33% hemihypophysectomy, 14% selective adenomectomy) but not remission (75% total hypophysectomy, 87% hemihypophysectomy, 71% selective adenomectomy). Among complications, an excess of venous thromboembolic disease was noted, with three patients (6%) developing deep venous thrombosis or pulmonary embolism postoperatively. Comparison of the data for individual surgeons revealed an improvement in outcome over time, with 100% remission of microadenomas, 29% hypopituitarism and 12% complications following the move to a single surgeon undertaking all pituitary surgery.

CONCLUSION

Transsphenoidal surgery is a safe and effective treatment for Cushing's disease and our results compare favourably with those from published series, the majority of which comprise relatively small numbers. The presence of an intrasellar lesion and postoperative serum cortisol < 50 nmol/l are good predictors of remission in the long term but historically in our centre this can only be achieved in a significant number of patients at the expense of some degree of hypopituitarism. However, the surgical outcome for Cushing's disease, including a reduced frequency of hypopituitarism, can be improved if patients are operated on by a single pituitary surgeon, using selective adenomectomy as the preferred surgical approach wherever possible.

Loss of ACTH expression in cultured human corticotroph macroadenoma cells is consistent with loss of the POMC gene signal sequence

The proopiomelanocortin (POMC) gene is highly expressed in the pituitary gland where the resulting mRNA of 1200 base pairs (bp) gives rise to a full-length protein sequence. In peripheral tissues however both shorter and longer POMC variants have been described, these include for example placental tissue which contain 800 (truncated at the 5' end) and 1500 as well as the 1200 bp transcripts. The importance of the 800 bp transcript is unclear as the lack of a signal sequence renders the molecule to be non-functional. This transcript has not been previously demonstrated in the pituitary gland. In this report we show evidence of a 5' truncated POMC gene in human pituitary corticotroph macroadenoma cells (JE) maintained in primary culture for >1 year. The original tumour tissue and the derived cells during early passage (up to passage 4-5) immunostained for ACTH and in situ hybridisation confirmed the presence of the POMC gene in the cultured cells. These cells also secreted 15-40 pg/10(5) cells/24 h ACTH. In addition, as expected RT-PCR demonstrated the presence of all three POMC gene exons and is thus indicative of a full-length POMC gene. In late culture passages (passages 8-15) JE cells ceased to express ACTH and cell growth became very slow due presumably to cells reaching their Hayflick limit. ACTH immunostaining in these cells was undetectable and ACTH secretion was also at the detection limits of the assay and no greater than 10 pg/10(5) cells/24 h. ACTH precursor molecules were also undetectable. RT-PCR for the POMC gene in these late passage cells showed that only exon 3 was detectable, in contrast to early passage cells where all three exons were present. In summary we isolated in culture, human pituitary cells that possessed initially all three exons of the POMC gene and immunostained for ACTH. On further passaging these cells showed a loss of exons 1 and 2 in the POMC gene and a loss of ACTH immunostaining and secretion. We would like to suggest that the loss of ACTH peptide expression in these late passage cells is in part due to the loss of the POMC signal sequence. An alternative explanation for our findings is that there were originally two populations of corticotrophs in the cultures, one of which possessed the full-length POMC gene and the other only the 5' truncated POMC transcript and it is these latter cells which survived in culture. In either scenario this is the first report of the 5' truncated POMC gene occurring in pituitary cells.

A therapeutic trial of growth hormone in hypopituitary adults and its influence upon continued prescription by general practitioners

OBJECTIVES

Adult GH deficiency (GHD) is associated with profound alterations in body composition, lipid profiles and quality of life which frequently improve after GH therapy. However, the beneficial effects of treatment are not derived by all and consequently some scepticism persists with regard to the use of GH therapy in adults. We assessed whether a 3-month therapeutic assessment with GH therapy could be used to determine which GHD adults should be treated over the longer term. We also assessed the continued prescription of GH by general practitioners (GPs) following the initial therapeutic assessment.

DESIGN

A three month open therapeutic trial of GH in GHD adults. Patients were treated with GH at an initial dose of 0.01 iU/kg/d, increased after 1 month to 0.015 iU/kg/d for males and 0.02 iU/kg/d for females. After completion of the three months the continued prescription of GH by the GPs was assessed.

PATIENTS

All adult GHD patients were considered for GH therapy. Thirty-nine GHD adults wanted GH therapy (group 1) and their baseline characteristics such as age, duration of GHD, and IGF-1 concentration were compared with 24 subjects who declined to receive GH (group 2).

MEASUREMENTS

Measurements of body composition using bioelectrical impedance analysis, lipids and quality of life measured using a dedicated questionnaire were made before and after GH therapy. The response of the general practitioners to continued GH therapy after the initial therapeutic assessment was also noted.

RESULTS

Compared with subjects who declined GH therapy (group 2), subjects of group 1 were younger (46.4 +/- 14.4 vs. 54.2 +/- 15.7 years, P < 0.05) and had lower peak GH responses to provocative testing (1.4 +/- 2.1 vs. 2.9 +/- 2.7 mU/l, P < 0.001), though there were no differences between IGF-1 concentration (11.7 +/- 6.2 vs. 14. 2 +/- 7.9 nmol/l). Following three months of GH therapy, there were significant improvements in all measured parameters including increased free fat mass (50.2 vs. 52.4 kg, P < 0.005) and total body water (37 vs. 38.7 l, P < 0.005), reduced fat mass (31.6 vs. 29.8 kg, P < 0.005), reduced AGHDA score (7 vs. 4, P < 0.001) and reduced cholesterol (6.3 vs. 5.8 mmol/l, P < 0.001), LDL (4 vs. 3.33 mmol/l, P < 0.001) and cholesterol/HDL ratio (5.57 vs. 4.67, P < 0.001). IGF-1 concentrations were significantly increased following treatment (12 vs. 32.4 nmol/l). Six subjects decided to discontinue GH therapy, 2 before the end of the study due to potential drug-related side-effects and 4 subjects derived no benefit from treatment. Despite the demonstrable benefits of treatment for the remaining 33 GHD adults, 6 GPs refused to continue to prescribe GH therapy for reasons of lack of familiarity with the drug or advice from their health authority.

CONCLUSION

Patients who wanted GH therapy were usually younger and more severely GHD than counterparts who elect not to be treated. However, a therapeutic trial of GH therapy is required to distinguish those subjects who derive benefit from treatment. We have shown that three months of low dose GH therapy is a sufficient period to elicit significant beneficial responses in quality of life, body composition parameters and lipids for the majority of patients and appears to be a sufficient period for patients to decide whether they want longer term therapy. The initial therapeutic trial also provides the objective evidence for the general practitioners to decide upon the continued prescription of therapy. Despite the positive evidence provided by this study, a small minority of general practitioners still refuse to prescribe GH therapy.

Novel pyroelectric sensor materials

Ceramic compositions of barium strontium titanium oxide (BSTO) have been formulated for applications as pyroelectric sensor materials. The material has been fabricated in tape-cast and thin film forms. In general, the materials demonstrated high pyroelectric coefficients (p) accompanied with low dielectric constant and low dissipation factor. The compositions of the tape-cast and thin film specimens examined in this paper include a well-known commercially adopted Ba_0.64Sr_0.36TiO₃ as well as a composition suggested in the literature, and a patented composition with the addition of MgO to BSTO is investigated. Doping BSTO with MgO has been shown to reduce the dielectric constant and loss tangent (over a very wide frequency range from 100 Hz-10 GHz) of the material and thereby increase the pyroelectric figure of merit. This article will discuss the processing, material characterization, pyroelectric coefficient, and pyroelectric figure-of-merit of the above mentioned BSTO compositions.