Thomas M. Barber

Obesity and polycystic ovary syndrome

The aetiology of Polycystic Ovary Syndrome (PCOS) is complex and multifactorial. There is much evidence, however, to suggest that adipose tissue plays an important role in the development and maintenance of PCOS pathology. There is a close correlation between adiposity and symptom severity in women with PCOS, and even modest reductions in weight generally translate into significant improvements in menstrual regularity, fertility and hyperandrogenic features. This review article considers the various mechanisms that might underlie this link between excess adiposity and PCOS – including the effects of differential insulin sensitivity, abnormal steroid hormone metabolism and adipocytokine secretion. Greater attention to the therapeutic options available to reduce the impact of excess adiposity on ovarian and metabolic function is essential to the management of PCOS.

Metabolic characteristics of women with polycystic ovaries and oligo‐amenorrhoea but normal androgen levels: implications for the management of polycystic ovary syndrome

Objective  Application of the newly introduced Rotterdam criteria for polycystic ovary syndrome (PCOS) generates four phenotypic subgroups, defined by the presence/absence of three diagnostic elements: polycystic ovarian (PCO) morphology (P); hyperandrogenism (H); and oligo‐amenorrhoea (O). Whilst PCOS is associated with adverse metabolic features, the strength of the association within individual subgroups is not established. We characterized the metabolic and endocrine profiles of PCOS women who are oligomenorrhoeic but normoandrogenaemic, and compared these to other PCOS women and controls.

Effects of supplemented isoenergetic diets differing in cereal fiber and protein content on insulin sensitivity in overweight humans

BACKGROUND Despite their beneficial effects on weight loss and blood lipids, high-protein (HP) diets have been shown to increase insulin resistance and diabetes risk, whereas high-cereal-fiber (HCF) diets have shown the opposite effects on these outcomes. OBJECTIVE We compared the effects of isoenergetic HP and HCF diets and a diet with moderate increases in both cereal fibers and dietary protein (Mix diet) on insulin sensitivity, as measured by using euglycemic-hyperinsulinemic clamps with infusion of [6,6-(2)H(2)]glucose. DESIGN We randomly assigned 111 overweight adults with features of the metabolic syndrome to 1 of 4 two-phased, 18-wk isoenergetic diets by group-matching. Per 3-d food protocols, the percentages of energy derived from protein and carbohydrates and the intake of cereal fiber per day, respectively, were as follows-after 6 wk: 17%, 52%, and 14 g (control); 17%, 52%, and 43 g (HCF); 28%, 43%, and 13 g (HP); 23%, 44%, and 26 g (Mix); after 18 wk: 17%, 51%, and 15 g (control); 17%, 51%, and 41 g (HCF); 26%, 45%, and 14 g (HP); and 22%, 46%, and 26 g (Mix). Eighty-four participants completed the study successfully and were included in the final analyses. Adherence was supported by the provision of tailored dietary supplements twice daily in all groups. RESULTS Insulin sensitivity expressed as an M value was 25% higher after 6 wk of the HCF diet than after 6 wk of the HP diet (subgroup analysis: 4.61 ± 0.38 compared with 3.71 ± 0.36 mg · kg(-1) · min(-1), P = 0.008; treatment × time interaction: P = 0.005). Effects were attenuated after 18 wk (treatment × time interaction: P = 0.054), which was likely explained by lower adherence to the HP diet. HP intake was associated with a tendency to increased protein expression in adipose tissue of the translation initiation factor serine-kinase-6-1, which is known to mediate amino acid-induced insulin resistance. Biomarkers of protein intake indicated interference of cereal fibers with dietary protein absorption. CONCLUSION Greater changes in insulin sensitivity after intake of an isoenergetic HCF than after intake of an HP diet might help to explain the diverse effects of these diets on diabetes risk. This trial is registered at clinicaltrials.gov as NCT00579657.

Increased 5α-Reductase Activity and Adrenocortical Drive in Women with Polycystic Ovary Syndrome

CONTEXT Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism, anovulation, and susceptibility to the metabolic syndrome. Altered peripheral cortisol metabolism has been reported in PCOS, but also in simple obesity. OBJECTIVE The aim of the study was to describe cortisol metabolism and metabolic characteristics of a large PCOS cohort and to delineate the effect of obesity by comparison to body mass index (BMI)-matched controls. DESIGN AND SETTING We conducted an observational, cross-sectional study at outpatient clinics of two secondary/tertiary care centers. PATIENTS OR OTHER PARTICIPANTS A total of 178 PCOS patients fulfilling Rotterdam criteria and 100 BMI-matched controls participated in the study. INTERVENTION The study included 24-h urine collection for steroid metabolite excretion and fasting blood samples, followed by an oral glucose tolerance test. MAIN OUTCOME MEASURES We measured urinary steroid metabolites including glucocorticoids and androgens and the ratios reflecting enzymatic activities involved in peripheral cortisol and androgen metabolism, 5 alpha-reductase, and 11 beta-hydroxysteroid dehydrogenase types 1 and 2. We also measured circulating levels of glucose, insulin, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone and calculated homeostasis model assessment. RESULTS Total androgen metabolites were higher in PCOS patients compared to BMI-matched controls (4,105 +/- 2,047 vs. 2,532 +/- 1,610 microg/24 h for the nonobese; 5,547 +/- 2,911 vs. 2,468 +/- 1,794 microg/24 h for the obese; both P < 0.001). Total glucocorticoid metabolites were higher in obese PCOS vs. controls (10,786 +/- 3,852 vs. 8,834 +/- 4,487 microg/24 h; P = 0.001). 5 alpha-Reductase activity correlated with BMI, insulin levels, and homeostasis model assessment. Both obese and nonobese PCOS patients had higher 5 alpha-reductase activity than controls (all P < 0.05). 11 beta-Hydroxysteroid dehydrogenase activities did not differ between PCOS and controls. CONCLUSIONS PCOS is associated with enhanced androgen and cortisol metabolite excretion and increased 5 alpha-reductase activity that cannot be explained by obesity alone. Increased adrenal corticosteroid production represents an important pathogenic pathway in PCOS.

The identification of irisin in human cerebrospinal fluid: influence of adiposity, metabolic markers, and gestational diabetes.

Peripheral action of irisin improves glucose homeostasis and increases energy expenditure, with no data on a central role of irisin in metabolism. These studies sought to examine 1) presence of irisin in human cerebrospinal fluid (CSF) and banked human hypothalamic tissue, 2) serum irisin in maternal subjects across varying adiposities with or without gestational diabetes (GDM), and 3) their respective neonate offspring. CSF, serum, and neonatal cord serum were collected from 91 pregnant women with and without GDM attending for an elective cesarean section [body mass index (BMI): 37.7 ± 7.6 kg/m(2); age: 32 ± 8.3 yr]. Irisin was assessed by ELISA and correlated with biochemical and anthropometric data. Irisin expression was examined in human hypothalamus by immunohistochemical staining. Serum irisin in pregnant women was significantly lower in nonobese compared with obese and GDM subjects, after adjusting for BMI, lipids, and glucose. Irisin was present in neonatal cord serum (237 ± 8 ng/ml) and maternal CSF (32 ± 1.5 ng/ml). CSF irisin correlated positively with serum irisin levels from nonobese and obese pregnant women (P < 0.01), with CSF irisin significantly raised in GDM subjects (P < 0.05). Irisin was present in human hypothalamic sections in the paraventricular neurons, colocalized with neuropeptide Y. Irisin was detectable in CSF and in paraventricular neurons. Maternal serum irisin was lower in nonobese pregnant women after adjusting for BMI and a number of metabolic parameters. These studies indicate that irisin may have a central role in metabolism in addition to the known peripheral role. Further studies investigating the central action of irisin in human metabolic disease are required.

Nelson's syndrome

Nelsons syndrome is a potentially life-threatening condition that does not infrequently develop following total bilateral adrenalectomy (TBA) for the treatment of Cushings disease. In this review article, we discuss some controversial aspects of Nelsons syndrome including diagnosis, predictive factors, aetiology, pathology and management based on data from the existing literature and the experience of our own tertiary centre. Definitive diagnostic criteria for Nelsons syndrome are lacking. We argue in favour of a new set of criteria. We propose that Nelsons syndrome should be diagnosed in any patient with prior TBA for the treatment of Cushings disease and with at least one of the following criteria: i) an expanding pituitary mass lesion compared with pre-TBA images; ii) an elevated 0800 h plasma level of ACTH (>500 ng/l) in addition to progressive elevations of ACTH (a rise of >30%) on at least three consecutive occasions. Regarding predictive factors for the development of Nelsons syndrome post TBA, current evidence favours the presence of residual pituitary tumour on magnetic resonance imaging (MRI) post transsphenoidal surgery (TSS); an aggressive subtype of corticotrophinoma (based on MRI growth rapidity and histology of TSS samples); lack of prophylactic neoadjuvant pituitary radiotherapy at the time of TBA and a rapid rise of ACTH levels in year 1 post TBA. Finally, more studies are needed to assess the efficacy of therapeutic strategies in Nelsons syndrome, including the alkylating agent, temozolomide, which holds promise as a novel and effective therapeutic agent in the treatment of associated aggressive corticotroph tumours. It is timely to review these controversies and to suggest guidelines for future audit.

Adipocyte biology in polycystic ovary syndrome

Polycystic Ovary Syndrome (PCOS) is a common endocrinopathy that is associated with an adverse metabolic profile including insulin resistance. There is a clear association between obesity, the development of PCOS and the severity of its phenotypic, biochemical and metabolic features. Evidence to support this link includes data from epidemiological, pathophysiological and genetic studies. Given the importance of obesity in the development and manifestation of PCOS, ongoing research into the many facets of adipocyte biology in women with the condition is important and should continue to be a priority. In this review article, we discuss the existing literature on fat distribution, adipokines, adipocyte hypertrophy and adipocyte steroid metabolism in women with PCOS.

Serum Levels of Retinol-Binding Protein 4 and Adiponectin in Women with Polycystic Ovary Syndrome: Associations with Visceral Fat But No Evidence for Fat Mass-Independent Effects on Pathogenesis in This Condition

CONTEXT Insulin resistance, which associates with levels of retinol-binding protein 4 (RBP4) and adiponectin, is implicated in the development of polycystic ovary syndrome (PCOS). OBJECTIVE The objective of the study was to explore the potential contribution of RBP4 and adiponectin in the etiology of PCOS and their relationships with specific fat depot measurements. DESIGN This was a cross-sectional study. SETTING AND PARTICIPANTS Serum RBP4 and adiponectin levels were compared between 50 PCOS cases and 28 female controls (including 22 body mass index/fat mass-matched pairs) and correlated with specific fat depot (including visceral) axial magnetic resonance imaging cross-sectional area measurements. All subjects were of U.K. British/Irish origin. MAIN OUTCOME MEASURE(S) Serum levels of RBP4 (automated immunonephelometric assay) and adiponectin [immunoassay: total and high molecular weight (HMW)]. Data are reported as geometric mean (sd, range) and optionally adjusted for fat mass and age. RESULTS Between the 50 PCOS cases and 28 controls, serum RBP4 levels were indistinguishable [39.0 microg/ml (31.0, 49.0) vs. 41.6 microg/ml (32.7, 52.9), respectively, unadjusted P = 0.24; adjusted P = 0.55]. Total (and HMW) adiponectin levels were lower in PCOS cases [total adiponectin 19.9 microg/ml (14.2, 27.8) vs. 25.8 microg/ml (17.7, 37.7), respectively, unadjusted P = 2.4 x 10(-3); adjusted P = 0.10]. For the paired-sample analyzes, there were no differences in RBP4 (P = 0.09), total adiponectin (P = 0.06), HMW adiponectin (P =0.19), or HMW to total adiponectin ratio (P = 0.98). In PCOS cases, L4-visceral fat area was associated positively with RBP4 (r(2) = 0.34, P = 0.01) and negatively with HMW to total adiponectin ratio (r(2) = -0.44, P = 1.3 x 10(-3)). Controls showed similar relationships. CONCLUSIONS Although associated with visceral fat, serum RBP4 and adiponectin levels do not play important, fat-mass-independent primary roles in the development of PCOS.

The role of obesity and type 2 diabetes mellitus in the development of male obesity‐associated secondary hypogonadism

Obesity, secondary (hypogonadotrophic) hypogonadism (SH), sleep disorders [such as obstructive sleep apnoea (OSA)] and type 2 diabetes mellitus (T2DM) in men have complex interlinks both with respect to mutual aetiopathogenesis as well as therapeutics. Correction of the attendant hypogonadism in obese men may serve to break this link and have beneficial effects beyond restoration of normal sexual function. Male obesity‐associated secondary hypogonadism (MOSH) should be regarded as a distinct clinical entity and subtype of SH. A high index of suspicion for the presence of MOSH must be maintained by clinicians when assessing obese men. The pathogenesis of MOSH remains incompletely understood. Furthermore, the optimal management of MOSH and its associated sequelae will require long‐term prospective studies that in turn will inform the development of future clinical guidelines for this important and prevalent condition.

Ghrelin levels are suppressed and show a blunted response to oral glucose in women with polycystic ovary syndrome.

OBJECTIVE Abnormal ghrelin regulation may influence the development of obesity-associated conditions including polycystic ovary syndrome (PCOS). Our aim was to compare ghrelin regulation between PCOS cases and controls. DESIGN We compared serum ghrelin (total) levels, fasting and 30-min post-oral (75 g) glucose load, between 50 PCOS cases and 28 female controls, including 22 body mass index (BMI)/fat mass-matched pairs. All subjects were of UK British/Irish origin. METHODS Measurements included serum ghrelin (RIA technique (LINCO Research, St Charles MO, USA)), fat mass, serum testosterone, fasting serum insulin and plasma glucose levels. Insulin sensitivity was calculated as the homeostasis model assessment of insulin resistance (HOMA2 IR). RESULTS Fasting serum ghrelin levels were significantly lower in PCOS cases versus BMI/fat mass-matched controls (geometric mean (s.d. range), 1104 pg/ml (764-1595) vs 1756 pg/ml (1314-2347) respectively; P=2.3 x 10(-4)). Ghrelin suppression following oral glucose load was significantly blunted in PCOS cases versus BMI/fat mass-matched controls (geometric mean ghrelin suppression (s.d. range), 160 pg/ml (88-289) vs 424 pg/ml (220-818) respectively; P=2.0 x 10(-4)). Whole-group comparisons (50 PCOS cases versus 28 controls) adjusted for fat mass and age revealed similar results. In PCOS cases, there was a significant negative correlation between fasting serum ghrelin and HOMA2 IR (r(2)=-0.40, P=5.7 x 10(-3)). Following adjustment for HOMA2 IR, fat mass and age, comparisons between the whole groups of PCOS cases and controls revealed attenuated but significant differences in fasting serum ghrelin (P=1.3 x 10(-3)) and ghrelin suppression (P=1.8 x 10(-3)). CONCLUSIONS In women with PCOS, serum ghrelin levels are suppressed, showing a negative relationship with HOMA2 IR and a blunted response to oral glucose.