Genetic screening of hypertensive patients with aldosterone hypersecretion under conditions of stress

PURPOSE

Although ACTH is considered a secondary regulator of aldosterone production, patients with apparent essential hypertension have been treated with mineralocorticoid receptor antagonists (MRAs). In this study, we aimed to identify potentially damaging variants that might be implicated in the phenotype of a well-characterized cohort of 21 hypertensive patients without PA but with stress-induced aldosterone hypersecretion. The patients' blood pressure was normalized though MRA administration.

METHODS

Genetic screening was performed through whole-exome sequencing (WES), and variants in PA-associated or in ion-channels of aldosterone-regulating genes were prioritized. Variants with population frequency < 0.01, predicted to alter protein structure and classified as likely pathogenic by in silico tools, were retained.

RESULTS

Qualifying variants were identified in nine of the 21 patients screened. Seven patients were carriers of six potentially damaging variants in six genes associated with PA (KCNK9, KCNK5, ATP13A3, SLC26A2, CACNA1H, and CACNA1D). A novel variant in the KCNK9 gene (p.V221M) is reported. Our analysis revealed two variants in two novel susceptibility genes for aldosterone hypersecretion, namely, KCNK16 (p.P255H) and CACNA2D3 (p.V557I).

CONCLUSION

WES revealed potentially damaging germline variants in genes participating in aldosterone synthesis/regulating pathways in 9/21 patients of our cohort. The variants identified might play a role in aldosterone hypersecretion under conditions of stress. The potential pathogenicity of these variants should be examined in future functional studies.

Unravelling the Genetic Basis of ACTH-Mediated Aldosterone Hypersecretion in Hypertensive Patients Without Primary Aldosteronism

Introduction: Primary aldosteronism (PA), a condition characterized by autonomous aldosterone hypersecretion, constitutes the most common cause of secondary hypertension. PA includes both sporadic and familial forms, inherited in an autosomal dominant manner. Recent evidence suggests a higher prevalence of aldosterone excess among hypertensive patients than previously thought, while chronic stress-related ACTH-mediated aldosterone hypersecretion has also been implicated in the pathogenesis of essential hypertension. Objective: To determine whether genetic variations of aldosterone regulating genes could be implicated in the ACTH-mediated aldosterone hypersecretion in hypertensive patients without PA. Methods: Twenty-one hypertensive patients without PA, who exhibited ACTH-mediated aldosterone hypersecretion, underwent Whole Exome Sequencing (WES) on Novaseq 6000 platform (Illumina). As hyper-responders were defined patients whose aldosterone (ALD) and aldosterone-to-renin ratio (ARR) response to ultra-low ACTH stimulation test was above the 97.5th percentile values of controls. The cutoff levels for ALD and ARR were 1300 pmol/L and 77 pmol/mIU, respectively. Variant calling was performed according to GATK best practices and VCF files were filtered for variants in 25 genes associated with PA. To identify new susceptibility genes for PA, VCF files were also intersected for variants in ion channels encoding genes involved in pathways responsible for PA. The analysis was restricted to rare variants with gnomAD frequency &lt; 1%. Qualifying variants and pathogenicity were established by employing in silico tools. Copy Number Variant analysis was performed using ExomeDepth algorithm. Results: Eight out of twenty-one patients were heterozygous for rare variants in genes associated with PA, while two patients carried potentially damaging variants in genes encoding ion channels. Specifically, one patient was heterozygous for p.V259M in KCNK5 and one patient was heterozygous for the novel variant p.V221M in KCNK9. Two additional patients carried a predicted pathogenic variant p.R492W in SLC26A2, a gene that has been associated with PA through GWAS. Germline variants in calcium channel genes were also detected in three patients: p.V249I in CACNA1H, p.R462Q in CACNA1D and p.L1801M in CACNA1I, while one patient carried an ultra-rare variant (p.R26L) in ATP13A3. Finally, in two patients we identified rare, likely pathogenic variants in two new susceptibility genes for PA: KCNK16 (p.P255H) and CACNA2D3 (p.V55I). Conclusion: These findings support the notion that mutations in aldosterone synthesis/secretion regulating genes may sensitize zone glomerulosa cells to ACTH stimulation, leading to aldosterone hypersecretion under conditions of stress. We also report two novel candidate susceptibility genes for PA, KCNK16 and CACNA2D3, and one novel variant in KCNK9.

Sociodemographic and lifestyle-related risk factors for identifying vulnerable groups for type 2 diabetes: a narrative review with emphasis on data from Europe

BACKGROUND

Type 2 diabetes mellitus (T2DM) comprises the vast majority of all diabetes cases in adults, with alarmingly increasing prevalence over the past few decades worldwide. A particularly heavy healthcare burden of diabetes is noted in Europe, where 8.8% of the population aged 20-79 years is estimated to have diabetes according to the International Diabetes Federation. Multiple risk factors are implicated in the pathogenesis of T2DM with complex underlying interplay and intricate gene-environment interactions. Thus, intense research has been focused on studying the role of T2DM risk factors and on identifying vulnerable groups for T2DM in the general population which can then be targeted for prevention interventions.

METHODS

For this narrative review, we conducted a comprehensive search of the existing literature on T2DM risk factors, focusing on studies in adult cohorts from European countries which were published in English after January 2000.

RESULTS

Multiple lifestyle-related and sociodemographic factors were identified as related to high T2DM risk, including age, ethnicity, family history, low socioeconomic status, obesity, metabolic syndrome and each of its components, as well as certain unhealthy lifestyle behaviors. As Europe has an increasingly aging population, multiple migrant and ethnic minority groups and significant socioeconomic diversity both within and across different countries, this review focuses not only on modifiable T2DM risk factors, but also on the impact of pertinent demographic and socioeconomic factors.

CONCLUSION

In addition to other T2DM risk factors, low socioeconomic status can significantly increase the risk for prediabetes and T2DM, but is often overlooked. In multinational and multicultural regions such as Europe, a holistic approach, which will take into account both traditional and socioeconomic/socioecological factors, is becoming increasingly crucial in order to implement multidimensional public health programs and integrated community-based interventions for effective T2DM prevention.

DIAGNOSIS OF ENDOCRINE DISEASE: Drug-induced endocrinopathies and diabetes: a combo-endocrinology overview

In the currently overwhelming era of polypharmacy, the balance of the dynamic and delicate endocrine system can easily be disturbed by interfering pharmaceutical agents like medications. Drugs can cause endocrine abnormalities via different mechanisms, including direct alteration of hormone production, changes in the regulation of the feedback axis, on hormonal transport, binding and signaling, as well as similar changes to counter-regulatory hormone systems. Furthermore, drugs can interfere with the hormonal assays, leading to erroneous laboratory results that disorientate clinicians from the right diagnosis. The purpose of this review is to cover a contemporary topic, the drug-induced endocrinopathies, which was presented in the monothematic annual Combo Endo Course 2018. This challenging part of endocrinology is constantly expanding particularly during the last decade, with the new oncological therapeutic agents, targeting novel molecular pathways in the process of malignancies. In this new context of drug-induced endocrine disease, clinicians should be aware that drugs can cause endocrine abnormalities via different mechanisms and mimic a variety of clinical scenarios. Therefore, it is extremely important for clinicians not only to promptly recognize drug-induced hormonal and metabolic abnormalities, but also to address the therapeutic issues for timely intervention.

Adiponectin circulating levels and 10-year (2002-2012) cardiovascular disease incidence: the ATTICA Study

PURPOSE

Adiponectin is an adipokine with anti-inflammatory and cardiovascular-protective properties. Existing epidemiological evidence is conflicting on the exact relationship between adiponectin and long-term cardiovascular disease (CVD) risk. Our aim was to prospectively assess whether circulating adiponectin is associated with long-term incident CVD.

METHODS

A population-based, prospective study in adults (>18 years) without previous CVD history (ATTICA study). Circulating total adiponectin levels were measured at baseline (2001-2002) in a sub-sample (n = 531; women/men: 222/309; age: 40 ± 11 years) of the ATTICA cohort and complete 10-year follow-up data were available in 366 of these participants (women/men: 154/212; age: 40 ± 12 years).

RESULTS

After adjusting for multiple factors, including age, sex, body mass index, waist circumference, smoking, physical activity, Mediterranean diet adherence, hypertension, diabetes, and hypercholesterolemia, our logistic regression analysis indicates that an increase in circulating total adiponectin levels by 1 unit was associated with 36% lower CVD risk (relative risk [RR]: 0.64, 95% confidence interval [CI] 0.42-0.96; p = 0.03). Further adjusting for interleukin-6 plasma levels had no significant impact (RR: 0.60, 95% CI 0.38-0.94; p = 0.03), while additional adjustment for circulating C-reactive protein (CRP) modestly attenuated this association (RR: 0.63, 95% CI 0.40-0.99; p = 0.046).

CONCLUSIONS

In our study, elevated circulating total adiponectin levels were associated with lower 10-year CVD risk in adults without previous CVD, independently of other established CVD risk factors. This association appeared to be modestly attenuated by CRP, yet was not mediated by interleukin-6 which is the main endocrine/circulating pro-inflammatory cytokine.

Modeling anthropometric indices in relation to 10-year (2002-2012) incidence of cardiovascular disease, among apparently healthy individuals: The ATTICA study

AIMS

Body fat accumulation is implicated in the development of cardiovascular disease (CVD). Our objective was to explore potential associations between anthropometric indices and the 10-year CVD incidence in Greek adults without previous CVD.

METHODS

During 2001-2, we enrolled 3042 adults without CVD from the general population of Attica, Greece. In 2011-2, the 10-year study follow-up was performed, recording the CVD incidence in 1958 participants with baseline body mass index (BMI) ≥18.5kg/m².

RESULTS

The study 10-year CVD incidence was 15.8%, exhibiting a gradual increase according to the baseline body mass index (BMI) category. Baseline BMI ≥30kg/m² was related with significantly higher 10-year CVD risk compared to BMI <25kg/m², even after adjustment for age and other known CVD risk factors. Baseline BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio and waist-to-hip-to-height ratio were independently associated with the 10-year CVD risk in multi-adjusted models. Gender-specific analyses showed that these associations were more evident in men compared to women, with baseline BMI exhibiting an independent association with the 10-year CVD incidence in men.

CONCLUSIONS

Our results indicate that even simple anthropometric indices exhibit independent associations with CVD risk in a representative sample of the Greek general population without previous CVD.

Visceral adiposity index and 10-year cardiovascular disease incidence: The ATTICA study

BACKGROUND AND AIMS

Visceral adiposity index (VAI) has been proposed as a marker of visceral adipose tissue accumulation/dysfunction. Our aim was to evaluate potential associations between the VAI and the 10-year cardiovascular disease (CVD) incidence.

METHODS AND RESULTS

During 2001-2002, 3042 Greek adults (1514 men; age: ≥18 years) without previous CVD were recruited into the ATTICA study, whilst the 10-year study follow-up was performed in 2011-2012, recording the fatal/non-fatal CVD incidence in 2020 (1010 men) participants. The baseline VAI scores for these participants were calculated based on anthropometric and lipid variables, while VAI tertiles were extracted for further analyses. During the study follow-up a total of 317 CVD events (15.7%) were observed. At baseline, the participants' age and the prevalence of hypertension, diabetes, hypercholesterolemia and metabolic syndrome increased significantly across the VAI tertiles. After adjusting for multiple confounders, VAI exhibited a significantly independent positive association with the 10-year CVD incidence (OR = 1.05, 95%CI: 1.01, 1.10), whereas the association of the body mass index (HR = 1.03, 95%CI: 0.99, 1.08), or the waist circumference (HR = 1.01, 95%CI: 0.99, 1.02) was less prominent. Sex-specific analysis further showed that VAI remained significantly predictive of CVD in men alone (HR = 1.06, 95%CI: 1.00, 1.11) but not in women (HR = 1.06, 95%CI: 0.96, 1.10).

CONCLUSIONS

Our findings show for the first time in a large-sample, long-term, prospective study in Europe that the VAI is independently associated with elevated 10-year CVD risk, particularly in men. This suggests that the VAI may be utilized as an additional indicator of long-term CVD risk for Caucasian/Mediterranean men without previous CVD.

J-shaped relationship between habitual coffee consumption and 10-year (2002-2012) cardiovascular disease incidence: the ATTICA study

PURPOSE

The purpose of this work was to evaluate the association between coffee consumption and 10-year cardiovascular disease (CVD) incidence in the ATTICA study, and whether this is modified by the presence or absence of metabolic syndrome (MetS) at baseline.

METHODS

During 2001-2002, 3042 healthy adults (1514 men and 1528 women) living in the greater area of Athens were voluntarily recruited to the ATTICA study. In 2011-2012, the 10-year follow-up was performed in 2583 participants (15% of the participants were lost to follow-up). Coffee consumption was assessed by a validated food-frequency questionnaire at baseline (abstention, low, moderate, heavy). Incidence of fatal or non-fatal CVD event was recorded using WHO-ICD-10 criteria and MetS was defined by the National Cholesterol Education Program Adult Treatment panel III (revised) criteria.

RESULTS

Overall, after controlling for potential CVD risk factors, the multivariate analysis revealed a J-shaped association between daily coffee drinking and the risk for a first CVD event in a 10-year period. Particularly, the odds ratio for low (<150 ml/day), moderate (150-250 ml/day) and heavy coffee consumption (>250 ml/day), compared to abstention, were 0.44 (95% CI 0.29-0.68), 0.49 (95% CI 0.27-0.92) and 2.48 (95% CI 1.56-1.93), respectively. This inverse association was also verified among participants without MetS at baseline, but not among participants with the MetS.

CONCLUSIONS

These data support the protective effect of drinking moderate quantities of coffee (equivalent to approximately 1-2 cups daily) against CVD incidents. This protective effect was only significant for participants without MetS at baseline.

Effects of a hops (Humulus lupulus L.) dry extract supplement on self-reported depression, anxiety and stress levels in apparently healthy young adults: a randomized, placebo-controlled, double-blind, crossover pilot study

OBJECTIVE

The Humulus lupulus L. plant (hops) is used as a herbal medicinal product for anxiety/mood disorders. Our aim was to study the effects of a hops dry extract on self-reported depression, anxiety and stress levels in young adults.

DESIGN

Apparently healthy young adults from our university completed the Depression Anxiety Stress Scale-21 (DASS-21) and those reporting at least mild depression, anxiety and stress were invited to complete the study intervention. This followed a randomized (1:1), placebo-controlled, double-blind, crossover design with two 4-week intervention periods (Melcalin hops or placebo; two 0.2 gr capsules once daily) separated by a 2-week wash-out. Anthropometric measurements, DASS-21 assessments and measurements of morning cortisol plasma levels were performed at the beginning and the end of the 4-week treatment periods.

RESULTS

36 participants (Females/Males: 31/5; age: 24.7±0.5 years) completed the study intervention (attrition: 6/42). No significant changes in body weight and composition or morning circulating cortisol were noted with the hops or placebo. Significantly decreased DASS-21 anxiety, depression and stress scores were documented with hops (9.2±7.3 vs. 5.1±5.9, 11.9±7.9 vs. 9.2±7.4, and 19.1±8.1 vs. 11.6±8.1; all p values <0.05), which were significantly greater compared to those caused by the placebo (all p values <0.05).

CONCLUSION

In otherwise healthy young adults reporting at least mild depression, anxietyand stress symptoms, daily supplementation with a hops dry extract can significantly improve all these symptoms over a 4-week period. These beneficial effects agree with the indication of hops for anxiety/mood disorders and restlessness, as approved by the German Commission E.

European Guidelines for Obesity Management in Adults

Obesity is a chronic metabolic disease characterised by an increase of body fat stores. It is a gateway to ill health, and it has become one of the leading causes of disability and death, affecting not only adults but also children and adolescents worldwide. In clinical practice, the body fatness is estimated by BMI, and the accumulation of intra-abdominal fat (marker for higher metabolic and cardiovascular disease risk) can be assessed by waist circumference. Complex interactions between biological, behavioural, social and environmental factors are involved in regulation of energy balance and fat stores. A comprehensive history, physical examination and laboratory assessment relevant to the patient's obesity should be obtained. Appropriate goals of weight management emphasise realistic weight loss to achieve a reduction in health risks and should include promotion of weight loss, maintenance and prevention of weight regain. Management of co-morbidities and improving quality of life of obese patients are also included in treatment aims. Balanced hypocaloric diets result in clinically meaningful weight loss regardless of which macronutrients they emphasise. Aerobic training is the optimal mode of exercise for reducing fat mass while a programme including resistance training is needed for increasing lean mass in middle-aged and overweight/obese individuals. Cognitive behavioural therapy directly addresses behaviours that require change for successful weight loss and weight loss maintenance. Pharmacotherapy can help patients to maintain compliance and ameliorate obesity-related health risks. Surgery is the most effective treatment for morbid obesity in terms of long-term weight loss. A comprehensive obesity management can only be accomplished by a multidisciplinary obesity management team. We conclude that physicians have a responsibility to recognise obesity as a disease and help obese patients with appropriate prevention and treatment. Treatment should be based on good clinical care, and evidence-based interventions; should focus on realistic goals and lifelong multidisciplinary management.

Stress and inflammatory biomarkers and symptoms are associated with bioimpedance measures

BACKGROUND

This large cross-sectional, multi-centre study evaluated the association of body composition measurements by a novel dual frequency bioimpedance device (BIA-ACC) with chronic stress/inflammation biomarkers and the presence of medically unexplained symptoms (MUS).

MATERIALS AND METHODS

Participants were adult Caucasians of both sexes and included 10,416 lean subjects with no MUS (Group A), 58,710 lean subjects with MUS (Group B) and 30,445 overweight/obese subjects with no MUS and excessive fat mass (FM) (Group C).

RESULTS

Total body extracellular water (ECW) was higher, while intracellular water (ICW) was lower in Group B than both other groups (P < 0.01). Group A had significantly lower FM and higher skeletal mass (SK) and phase angle (PA) than Group B and lower circulating high sensitivity (hs) CRP levels than both other groups. hsCRP was higher in Group C than Group A though (P < 0.01). Salivary cortisol in Group B was lower in the morning and higher in the evening than both other groups (P < 0.001), indicating circadian rhythm obliteration or reversal in this group. ECW correlated positively with serum hsCRP and 8 p.m. salivary cortisol, but negatively with 8 a.m. salivary cortisol, while PA correlated positively with 8 a.m. and negatively with 8 p.m. salivary cortisol and serum hsCRP. Both 8 a.m. and 8 p.m. salivary cortisol and serum hsCRP were associated with the presence of MUS and BIA-ACC measurements, including ECW, ICW, FM, SK and PA.

CONCLUSIONS

MUS is an index of chronic stress and inflammation and BIA-ACC may provide a useful, bloodless and rapid tool in the clinical setting, distinguishing patients with chronic stress/inflammation from healthy subjects and monitoring their response to treatment.

Criteria for EASO-collaborating centres for obesity management

Obesity is recognised as a global epidemic and the most prevalent metabolic disease world-wide. Specialised obesity services, however, are not widely available in Europe, and obesity care can vary enormously across European regions. The European Association for the Study of Obesity (EASO, www.easo.org) has developed these criteria to form a pan-European network of accredited EASO-Collaborating Centres for Obesity Management (EASO-COMs) in accordance with accepted European and academic guidelines. This network will include university, public and private clinics and will ensure that the obese and overweight patient is managed by a holistic team of specialists and receives comprehensive state-ofthe-art clinical care. Furthermore, the participating centres, under the umbrella of EASO, will work closely for quality control, data collection, and analysis as well as for education and research for the advancement of obesity care and obesity science.

Stress hormones: physiological stress and regulation of metabolism

Stress, defined as a state of threatened homeostasis, mobilizes a complex spectrum of adaptive physiologic and behavioral responses that aim to re-establish the challenged body homeostasis. The hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) constitute the main effector pathways of the stress system, mediating its adaptive functions. In western societies, indices of stress correlate with increasing rates of both obesity and metabolic syndrome which have reached epidemic proportions. Recent data indicate that chronic stress, associated with mild hypercortisolemia and prolonged SNS activation, favors accumulation of visceral fat and contributes to the clinical presentation of visceral obesity, type 2 diabetes, and related cardiometabolic complications. Reciprocally, obesity promotes a systemic low-grade inflammation state, mediated by increased adipokine secretion, which can chronically stimulate the stress system.

Chronic stress, visceral obesity and gonadal dysfunction

Chronic stress represents a prolonged state of dyshomeostasis caused by intense and frequently imposed stressors. Obesity constitutes a chronic dysmetabolic state, leading progressively to a spectrum of metabolic complications, such as diabetes, dyslipidemia, hypertension and cardiovascular disease. Alpha growing body of evidence supports the existence of significant interactions between stress and obesity, with chronic stress promoting weight gain, and consequently excessive fat accumulation especially visceral, all these factors contributing to the development of a chronic stressful state. Maintaining body homeostasis is a prerequisite for normal reproductive function, which is vital for the survival of the species and an important process of natural selection. Under chronic stress, reproductive function is suspended and disrupted due to central and peripheral actions of hormones, adipokines and pro-inflammatory cytokines that inhibit the activity of the hypothalamic-pituitary gonadal (HPG) axis at various levels. Clinical and experimental data link both obesity and chronic stress to dysregulation of the gonadal axis, via independent and synergistic mechanisms, which may chronically lead to reproductive dysfunction and reduced fertility.

Management of obesity in adults: European clinical practice guidelines

The development of consensus guidelines for obesity is complex. It involves recommending both treatment interventions and interventions related to screening and prevention. With so many publications and claims, and with the awareness that success for the individual is short-lived, many find it difficult to know what action is appropriate in the management of obesity. Furthermore, the significant variation in existing service provision both within countries as well as across the regions of Europe makes a standardised approach, even if evidence-based, difficult to implement. In formulating these guidelines, we have attempted to use an evidence-based approach while allowing flexibility for the practicing clinician in domains where evidence is currently lacking and ensuring that in treatment there is recognition of clinical judgment and of regional diversity as well as the necessity of an agreed approach by the individual and family. We conclude that i) physicians have a responsibility to recognise obesity as a disease and help obese patients with appropriate prevention and treatment, ii) treatment should be based on good clinical care and evidence-based interventions and iii) obesity treatment should focus on realistic goals and lifelong management.

Interdisciplinary European guidelines on surgery of severe obesity

In 2005, for the first time in European history, an extraordinary expert panel named BSCG (Bariatric Scientific Collaborative Group), was appointed through joint effort of the major European scientific societies which are active in the field of obesity management. Societies that constituted this panel were: IFSO - International Federation for the Surgery of Obesity, IFSO-EC - International Federation for the Surgery of Obesity - European Chapter, EASO - European Association for Study of Obesity, ECOG - European Childhood Obesity Group, together with the IOTF (International Obesity Task Force) which was represented during the completion process by its representative. The BSCG was composed not only of the top officers representing the respective scientific societies (four acting presidents, two past presidents, one honorary president, two executive directors), but was balanced with the presence of many other key opinion leaders in the field of obesity. The BSCG composition allowed the coverage of key disciplines in comprehensive obesity management, as well as reflecting European geographical and ethnic diversity. This joint BSCG expert panel convened several meetings which were entirely focused on guidelines creation, during the past 2 years. There was a specific effort to develop clinical guidelines, which will reflect current knowledge, expertise and evidence based data on morbid obesity treatment.

Visfatin, TNF-alpha and IL-6 mRNA expression is increased in mononuclear cells from type 2 diabetic women

Visfatin, is a new adipokine, highly expressed in the visceral fat of both mice and humans. To examine whether visfatin is expressed in human peripheral monocyte-enriched mononuclear cells and whether its expression is altered in type 2 diabetes (DM2), we compared 24 DM2 women [17 overweight (BMI >25) and 7 lean (BMI<25)] to 26 healthy women (14 overweight and 12 lean), all premenopausal. Relative visfatin mRNA levels were significantly higher (approximately 3-fold) in DM2 compared to healthy control women (p<0.02), independently of the presence of overweight/obesity. Mononuclear TNF-alpha and IL-6 mRNA expression was also elevated in DM2 compared to control women (p=0.001 and p=0.004, respectively), an increase observed in both lean and overweight DM2 women. By contrast, circulating visfatin, TNF-alpha, and IL-6 levels showed no difference between DM2 and control women, while adiponectin plasma levels were significantly decreased in the DM2 women (p<0.001). Circulating visfatin and TNF-alpha levels did not differ either between the lean and the overweight subgroups of DM2 and control women, while IL-6 plasma levels were significantly higher in both overweight subgroups compared to their lean counterparts. In conclusion, visfatin, TNF-alpha, and IL-6 mRNA expressions are increased in peripheral mononuclear-monocytic cells from women with type 2 diabetes, independent of their BMI, which may enhance the effects of their adipose-derived levels and may contribute to the increased insulin resistance and atherogenic risk of these patients.

Stress mechanisms and metabolic complications

Stress can be defined as a state of threatened homeostasis or disharmony. An intricate repertoire of physiologic and behavioral responses is mobilized under stressful situations forming the adaptive stress response that aims to reestablish the challenged body equilibrium. The hypothalamic-pituitary-adrenal axis and the central and peripheral components of the autonomic nervous system constitute the two main pillars that subserve the vital functions of the stress system. Chronic stress represents a prolonged threat to homeostasis that can progressively lead to a deleterious overload with various complications caused by both the persistent stressor and the detrimental prolongation of the adaptive response. Recent data indicate that chronic stress is associated to derangement of metabolic homeostasis that contributes to the clinical presentation of visceral obesity, type 2 diabetes, atherosclerosis and metabolic syndrome. Notably, indices of stress in the modern western societies correlate with the increasing incidence of both obesity and the metabolic syndrome which have reached epidemic proportions over the past decades. The pathogenetic mechanisms that accommodate these correlations implicate primarily the chronic hyperactivation of the HPA axis under prolonged stress, which favors accumulation of visceral fat, and VICE VERSA; obesity constitutes a chronic stressful state that may cause HPA axis dysfunction. In addition, obesity is being now recognized as a systemic low grade inflammatory state that contributes to the derangement of the metabolic equilibrium, implicating the adipocyte secretion of adipokines to the pathogenesis of several components of the metabolic syndrome. Understanding the mechanisms that mediate the documented reciprocal relationships between stress and metabolic homeostasis will hopefully provide novel insights to the pathophysiology of obesity, type 2 diabetes, and their cardiometabolic complications, and will help the quest for more specific and effective therapeutic interventions.

Stress, the endoplasmic reticulum, and insulin resistance

Stress, such as nutrient deprivation, viral infections, inflammation, heat shock, or lipid accumulation, imposes a serious threat to the body. These stimuli, acting both on the central control stations of the stress system and its final effectors, catecholamines and glucocorticoids, and on the peripheral target tissues, can modulate insulin action in the body. Metabolic complications, such as diabetes, visceral obesity, and atherosclerosis have emerged as major health threats in the modern societies. Indeed, obesity and atherosclerosis are regarded as states of chronic low-grade inflammation, while inflammatory mediators and lipid accumulation can evoke a chronic stress at the cellular level, principally affecting the endoplasmic reticulum (ER). It has recently been shown that ER responds to metabolic stressors through a well coordinated molecular response that involves the transcriptional activation of multiple genes, the attenuation of protein synthesis and degradation of the ER-localized misfolded proteins, and the onset of apoptosis. This article examines the emerging role of stress on ER and its possible link with obesity, insulin resistance, and type 2 diabetes.

Stress, visceral obesity, and metabolic complications

Stress is a state of threatened homeostasis or disharmony caused by intrinsic or extrinsic adverse forces and is counteracted by an intricate repertoire of physiologic and behavioral responses that aim to reestablish the challenged body equilibrium. The adaptive stress response depends upon an elaborate neuroendocrine, cellular, and molecular infrastructure, the stress system. Crucial functions of the stress system response are mediated by the hypothalamic-pituitary-adrenal (HPA) axis and the central and peripheral components of the autonomic nervous system (ANS). The integrity of the HPA axis and the ANS and their precise interactions with other CNS components are essential for a successful response to the various stressors. Chronic stress represents a prolonged threat to homeostasis by persistent or frequently repeated stressors and may lead to manifestations that characterize a wide range of diseases and syndromes. Such states progressively lead to a deleterious overload with complications caused by both the persistent stressor and the detrimental prolongation of the adaptive response. The metabolic syndrome can be described as a state of deranged metabolic homeostasis characterized by the combination of central obesity, insulin resistance, dyslipidemia, and hypertension. The incidence of both obesity and the metabolic syndrome in modern Western societies has taken epidemic proportions over the past decades and often correlates with indices of stress in the affected populations. Stress, primarily through hyperactivation of the HPA axis, appears to contribute to the accumulation of fat tissue, and vice versa, obesity itself seems to constitute a chronic stressful state and may cause HPA axis dysfunction. In addition, the description of obesity as a systemic low grade inflammatory condition that contributes to the derangement of the metabolic equilibrium implies that the proinflammatory cytokines which are secreted by the adipocytes hold a potentially important pathogenetic role. In this article we describe the physiology of the stress system response, with emphasis on metabolism, and review the recent data that implicate several neuroendocrine and inflammatory mechanisms mobilized during chronic stress in the development of the metabolic complications that characterize central obesity and the metabolic syndrome.

Inter-disciplinary European guidelines on surgery of severe obesity

In 2005, for the first time in European history, an extraordinary Expert panel named 'The BSCG' (Bariatric Scientific Collaborative Group), was appointed through joint effort of the major European Scientific Societies which are active in the field of obesity management. Societies that constituted this panel were: IFSO - International Federation for the Surgery of Obesity, IFSO-EC - International Federation for the Surgery of Obesity - European Chapter, EASO - European Association for Study of Obesity, ECOG - European Childhood Obesity Group, together with the IOTF (International Obesity Task Force) which was represented during the completion process by its representative. The BSCG was composed not only of the top officers representing the respective Scientific Societies (four acting presidents, two past presidents, one honorary president, two executive directors), but was balanced with the presence of many other key opinion leaders in the field of obesity. The BSCG composition allowed the coverage of key disciplines in comprehensive obesity management, as well as reflecting European geographical and ethnic diversity. This joint BSCG expert panel convened several meetings which were entirely focused on guidelines creation, during the past two years. There was a specific effort to develop clinical guidelines, which will reflect current knowledge, expertise and evidence based data on morbid obesity treatment.

Nutrition and Inflammatory Load

Chronic inflammation has been suggested to play an important role in metabolic diseases, such as atherothrombosis and type 2 diabetes. A lot of research has focused on the immunomodulatory effects of several nutrients, such as fatty acids, antioxidants, carbohydrates, specific amino acids, micronutrients, and alcohol, which play a crucial role in the maintenance of an "optimal" immune response. In addition, specific dietary patterns, such as the Mediterranean diet, are evolving as protective against cardiovascular disease, because of their anti-inflammatory properties. In this article, the existing data concerning the nutrients' pro- and anti-inflammatory properties are presented, as well as dietary patterns that could protect from chronic inflammation and its metabolic and atherothrombotic complications.

The Endocannabinoid System as a Target for the Treatment of Visceral Obesity and Metabolic Syndrome

The endogenous cannabinoid system is a novel, remarkably elaborate physiological signaling system, comprising the recently identified endogenous cannabinoid ligands, their corresponding selective receptors, and the machinery of proteins and enzymes that is involved in their biosynthesis, release, transport, and degradation. This system extends widely in both the central nervous system (CNS) and the periphery and exhibits a variety of actions implicated in vital functions (e.g., behavioral, antinociceptive, neuroprotective, immunosuppressive, cardiovascular, and metabolic). Particular interest has been focused on the apparent participation of endocannabinoids in metabolic homeostasis by modulating the activity of CNS circuits that control food intake and energy expenditure, the neuroendocrine response of the stress system, and the metabolic functions of crucial peripheral tissues, such as the adipose tissue, the gastrointestinal tract, the liver, and the skeletal muscles. These effects are predominantly CB(1) receptor mediated and, thus, selective antagonists of this receptor subtype are being vigorously investigated as potential therapeutic agents for the treatment of various metabolic derangements (e.g., obesity, insulin resistance, dyslipidemia, and metabolic syndrome). The first selective CB(1) receptor antagonist, rimonabant, has already successfully completed phase III clinical trials as adjunctive obesity treatment, with significant improvements in several associated metabolic and cardiovascular risk factors that led to the recent approval of its clinical use by the Food and Drug Administration.

Compound heterozygosity of a frameshift mutation in the coding region and a single base substitution in the promoter of the ACTH receptor gene in a family with isolated glucocorticoid deficiency

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive syndrome characterized by glucocorticoid insufficiency without mineralocorticoid deficiency. Mutations in the coding region of the ACTH receptor (MC2R) have been reported in several families with IGD. We amplified and sequenced the entire MC2R coding region in a new family with IGD. The proband was found to be heterozygous (paternal allele) for the mutation Gly217fs, which changes the open reading frame of the MC2R protein resulting in a truncated receptor. No other abnormality was found in the MC2R coding region. However, sequencing of the promoter region of the MC2R gene (-1017/44 bp) of the proband revealed a heterozygous T-->C substitution in the maternal allele at -2 bp position from initiation of the transcription start site. This substitution was found in only 6.5% in a healthy unrelated population. Constructs containing this polymorphism consistently showed a significant 15% decrease in promoter activity compared to wild type. In conclusion, we provide evidence that the IGD in this previously unreported family with ACTH resistance appears to be secondary to compound heterozygosity of a coding region and a promoter mutation in the MC2R gene.

Expression of leptin receptors in mononuclear cells from myelodysplastic syndromes and acute myeloid leukemias

Leptin, the adipocyte hormone, and its receptor have been implicated in the differentiation/proliferation of hematopoietic cells. Given that the deregulated expression of a variety of growth factors and/or their receptors has been implicated in the pathogenesis of certain leukemias, we aimed to characterize the potential differences in the expression pattern of the two major leptin receptor transcript variants in peripheral blood mononuclear cells (PBMC) between different hematologic malignancies. Using RT-PCR and Southern blotting, we compared the expression levels of the two major leptin receptors, the longest (OB-R(L)) and the shortest (OB-R(S)) splice variants, in PBMC from patients with myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), healthy individuals and two human hematopoietic cell lines (HL-60 and K562). Expression of the OB-R(S) transcript clearly exceeded that of OB-R(L) in all patients and controls and in the HL-60 cells, but this was reversed in the K562 cell line. However, the expression of the OB-R(L) was significantly lower in MDS compared to controls and tended to be so in AML, while OB-R(S) tended to be higher in MDS and AML patients compared to controls, but this difference was not significant. Serum leptin levels and circulating soluble leptin receptor levels were slightly but not significantly higher in AML and MDS. These alterations in the expression of the leptin receptor isoforms in MDS and AML patients could suggest a potential role of leptin and its signaling in hematopoietic malignancies, which requires further examination.

ENDOCRINOLOGY OF THE STRESS RESPONSE

The stress response is subserved by the stress system, which is located both in the central nervous system and the periphery. The principal effectors of the stress system include corticotropin-releasing hormone (CRH); arginine vasopressin; the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids; and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks, and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development and may account for a number of endocrine, metabolic, autoimmune, and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors, and the timing of the stressful events, given that prenatal life, infancy, childhood, and adolescence are critical periods characterized by increased vulnerability to stressors.

Differential effects of high-fat and high-carbohydrate content isoenergetic meals on plasma active ghrelin concentrations in lean and obese women

AIM

To study the effect of two different isoenergetic meals, one rich in carbohydrates and one rich in fat, on plasma active ghrelin levels in lean or obese subjects.

METHODS

Eight obese and eight lean women, strictly matched for age, were fed two isoenergetic meals of different composition, one rich in fat and one rich in carbohydrates (CHO), on separate days. Plasma active ghrelin levels were measured just before and at 1, 2 and 3 hours after meal consumption.

RESULTS

Overall, plasma active ghrelin levels were significantly lower in the obese compared to the lean women (71.7 +/- 29.7 vs. 222.2 +/- 127.2 pmol/liter respectively, p < 0.0001). Furthermore, ghrelin levels decreased significantly by 30 % from baseline values in the lean subjects in the first hour after the CHO-rich meal (mean difference +/- SD): -66.2 +/- 49.0 pmol/liter (p = 0.03), returning to near-baseline levels by 2 hours, while no significant change was observed in the obese subjects. After the fat-rich meal, active ghrelin levels did not change significantly in either group (p > 0.05).

CONCLUSIONS

A fat-rich meal does not suppress plasma active ghrelin levels in either lean or obese women. Moreover, in obese, unlike lean women, a high carbohydrate meal also fails to suppress plasma ghrelin levels, which are already quite low. This suggests that ghrelin-induced satiety mechanisms may be compromised in these subjects.

Differential effects of high-fat and high-carbohydrate isoenergetic meals on cardiac autonomic nervous system activity in lean and obese women

Food ingestion can influence autonomic nervous system activity. This study compares the effects of 2 different isoenergetic meals on sympathetic nervous system (SNS) activity, assessed by heart rate variability (HRV) and plasma norepinephrine (NE) levels, in lean and obese women. Fifteen lean and 15 obese healthy women were examined on 2 occasions: after a carbohydrate (CHO)-rich and after a fat-rich test meal. Measurements of blood pressure, heart rate, resting energy expenditure, plasma glucose, lipids, insulin, leptin, and NE, as well as spectral analysis of the HRV, were performed at baseline and every 1 hour for 3 hours after meals. At baseline, obese women had higher SNS activity than lean controls (higher values of low-to-high frequency ratio [LF/HF], 1.52 +/- 0.31 v 0.78 +/- 0.13, P=.04; and plasma NE levels, 405.6 +/- 197.9 v 240.5 +/- 95.8 pg/mL, P<.0001). After the CHO-rich meal a greater increase in LF/HF and in plasma NE levels was observed in lean, compared to obese women (1.21 +/- 0.6 v 0.32 +/- 0.06, P=.04; and 102.9 +/- 35.4 v 38.7 +/- 12.3 pg/mL, P=.01, respectively), while no differences were observed after the fat-rich meal. Meal-induced thermogenesis was higher after the CHO-rich as compared to the fat-rich meal and was comparable between lean and obese women. Changes in HRV were not associated with the thermogenic response to the test meals. In conclusion, consumption of a CHO-rich meal causes greater cardiac SNS activation in lean than in obese women, while fat ingestion does not result in any appreciable change in either group. SNS activation does not appear to influence the thermic effect of the food in either lean or obese women.

Hypothalamic-pituitary-adrenal axis, neuroendocrine factors and stress

The stress system coordinates the adaptive responses of the organism to stressors of any kind.(1). The main components of the stress system are the corticotropin-releasing hormone (CRH) and locus ceruleus-norepinephrine (LC/NE)-autonomic systems and their peripheral effectors, the pituitary-adrenal axis, and the limbs of the autonomic system. Activation of the stress system leads to behavioral and peripheral changes that improve the ability of the organism to adjust homeostasis and increase its chances for survival. The CRH and LC/NE systems stimulate arousal and attention, as well as the mesocorticolimbic dopaminergic system, which is involved in anticipatory and reward phenomena, and the hypothalamic beta-endorphin system, which suppresses pain sensation and, hence, increases analgesia. CRH inhibits appetite and activates thermogenesis via the catecholaminergic system. Also, reciprocal interactions exist between the amygdala and the hippocampus and the stress system, which stimulates these elements and is regulated by them. CRH plays an important role in inhibiting GnRH secretion during stress, while, via somatostatin, it also inhibits GH, TRH and TSH secretion, suppressing, thus, the reproductive, growth and thyroid functions. Interestingly, all three of these functions receive and depend on positive catecholaminergic input. The end-hormones of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, on the other hand, have multiple roles. They simultaneously inhibit the CRH, LC/NE and beta-endorphin systems and stimulate the mesocorticolimbic dopaminergic system and the CRH peptidergic central nucleus of the amygdala. In addition, they directly inhibit pituitary gonadotropin, GH and TSH secretion, render the target tissues of sex steroids and growth factors resistant to these substances and suppress the 5' deiodinase, which converts the relatively inactive tetraiodothyronine (T(4)) to triiodothyronine (T(3)), contributing further to the suppression of reproductive, growth and thyroid functions. They also have direct as well as insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome X) and direct effects on the bone, causing "low turnover" osteoporosis. Central CRH, via glucocorticoids and catecholamines, inhibits the inflammatory reaction, while directly secreted by peripheral nerves CRH stimulates local inflammation (immune CRH). CRH antagonists may be useful in human pathologic states, such as melancholic depression and chronic anxiety, associated with chronic hyperactivity of the stress system, along with predictable behavioral, neuroendocrine, metabolic and immune changes, based on the interrelations outlined above. Conversely, potentiators of CRH secretion/action may be useful to treat atypical depression, postpartum depression and the fibromyalgia/chronic fatigue syndromes, all characterized by low HPA axis and LC/NE activity, fatigue, depressive symptomatology, hyperalgesia and increased immune/inflammatory responses to stimuli.

Functional relationships between three novel homozygous mutations in the ACTH receptor gene and familial glucocorticoid deficiency

Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by a glucocorticoid adrenal insufficiency without mineralocorticoid deficiency. Mutations of the ACTH receptor (MC2-R) gene have been reported in some FGD cases, but only a few of them have been functionally studied. We reported clinical features and MC2-R gene analysis in three families. For each proband, an homozygous mutation was identified after amplification and sequencing of the whole intronless MC2-R gene. One mutation converted Val-142 located in the second intracellular loop to Leu. Another mutation in the sixth transmembrane domain converted Ala-233 to Pro. The last mutation converted the negatively charged Asp-103 in the first extracellular loop to an uncharged Asn. Functional studies of these mutations as well as the S120R mutation were performed after stable transfection of M3 cells and measurement of ACTH-induced cAMP production. For the S120R, V142L, and A233P mutated MC2-R, cAMP production curves were similar to that obtained with M3 parental cells, confirming that these mutations are responsible for the FGD in the affected patients. The D103N-mutated MC2-R had an impaired cAMP response to physiological doses of ACTH, but the maximal response at very high concentrations of ACTH was similar to that obtained for the wild-type MC2-R. All these results demonstrated clear relationships based on functional studies between MC2-R homozygous mutations and FGD phenotype.

The desmopressin and combined CRH-desmopressin tests in the differential diagnosis of ACTH-dependent Cushing's syndrome: constraints imposed by the expression of V2 vasopressin receptors in tumors with ectopic ACTH secretion

The role of desmopressin, alone or in combination with CRH, in the differential diagnosis between Cushing's disease (CD) and ectopic ACTH secretion (EAS) still remains uncertain. Based on existing data, the desmopressin test is regarded as an alternative to the CRH stimulation test and, when given in combination with CRH, it has been suggested to completely discriminate between patients with CD and EAS. However, assessment of these tests has been limited in only a small number of patients with EAS. Desmopressin is a relatively specific V2 vasopressin receptor (V2R) agonist. Although expression of V3 vasopressin receptor (V3R) is common in tumors with EAS, the expression of V2R has not been extensively investigated. In the present study, we report our findings of the desmopressin and the combined CRH-desmopressin test in a series of patients with CD and EAS; also, the expression of V2R and V3R was investigated in tumors with EAS by a RT-PCR method. We assessed a cohort of 31 patients with ACTH-dependent Cushing's syndrome, including 26 patients with CD and five cases with histologically confirmed EAS. To avoid bias of predetermined criteria, univariate curves of the receiver operating characteristics (ROC) were constructed by plotting the sensitivity against 1-specificity at each level of the percent cortisol (F) and ACTH responses to these tests. Following desmopressin administration there was an overlap of the percent F and ACTH responses among patients with CD and EAS, and the area under the ROC curve for both these responses was not significantly different than that occurring by chance. This was also true for the percent F response following the combined CRH-desmopressin test. However, the area under the ROC curve for the percent ACTH rise following the combined test was significantly different; the point of the ROC curve closest to 1 corresponded to a percent ACTH rise of 218% (88% sensitivity and 80% specificity). Expression of V2R and V3R mRNA was investigated in four of the five excised tumors with EAS and revealed the presence of the V2R in all, whereas the V3R mRNA was expressed in three of these cases. In conclusion, in this series the desmopressin test produced a significant overlap of responses between CD and patients with EAS and, therefore, is of limited value in the differential diagnosis of the ACTH-dependent Cushing's syndrome. This is most probably due to the expression of the V2R in tumors with EAS. Moreover, following the combined CRH-desmopressin test only the ACTH but not the F responses were diagnostically useful, but still far from completely discriminating patients with CD and EAS.

Monogenic forms of obesity and diabetes mellitus

Great progress has been made in identifying several genes and in understanding the molecular pathogenesis of inherited syndromes of obesity and diabetes mellitus (DM). In humans, mutations in leptin, leptin receptor, proopiomelanocortin (POMC), melanocortin-4 receptor (MC4R) and prohormone convertase 1 (PC1) have been described in patients with severe obesity. Most of these obesity disorders, with the exception of the MC4R mutations, exhibit recessive inheritance and a distinct phenotype with varying degrees of hypothalamic dysfunction, and they unravel the critical role of the central leptin and melanocortin pathways in human appetite control and energy homeostasis. Maturity onset diabetes of the young (MODY) is a genetically and clinically heterogeneous subtype of type 2 DM with early onset autosomal dominant inheritance and a primary defect in insulin secretion. To date, six MODY genes have been identified, the glucokinase gene and five beta cell-specific transcription factor genes, hepatocyte nuclear factor-1alpha (HNF-1alpha), HNF-1beta, HNF-4alpha, insulin promoter factor-1 (IPF-1) and NeuroD1/BETA2. Mitochondrial DNA mutations cause another form of DM with an insulin secretory defect that is commonly associated with neurosensory hearing impairment, and has strict maternal inheritance. At the other end of the spectrum are the inherited syndromes of insulin resistance that are caused by mutations in the insulin receptor gene and in the adipocyte-specific transcription factor PPARgamma. The advances in our knowledge of the phenotypic manifestations and underlying molecular mechanisms of genetic syndromes of obesity and DM raise expectations for molecular diagnosis, as well as for more etiological therapies and better prevention of the continuously increasing prevalence of obesity and DM in our modern societies.

TNFalpha and leptin inhibit basal and glucose-stimulated insulin secretion and gene transcription in the HIT-T15 pancreatic cells

BACKGROUND

Tumor necrosis factor alpha (TNFalpha), a cytokine produced at inflammatory sites and in adipose tissue, is known primarily for its detrimental effects on insulin action. There is evidence to suggest that TNFalpha may also influence beta-cell function. Leptin is another adipose tissue-derived hormone that might also act on beta-cells.

OBJECTIVE

We explored the independent and combined effects of TNFalpha and leptin upon basal and glucose-stimulated insulin transcription and secretion in the HIT-T15 pancreatic beta cell line.

METHODS

Cells were cultured for 40 h in the presence of near-normal basal (7 mM) or high (16.7 mM) glucose and treated with either TNFalpha (1, 10 and 50 ng/ml) or leptin (10, 50 and 100 ng/ml) or both together. Insulin concentrations were measured by radioimmunoassay. Insulin mRNA levels were evaluated by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) method, after normalization with beta-actin mRNA.

RESULTS

TNFalpha significantly suppressed basal and glucose-stimulated insulin secretion and proinsulin mRNA transcription in a dose-dependent manner, an effect that was more powerful in the presence of high glucose. Leptin also inhibited dose-dependent insulin mRNA and protein at both glucose concentrations, but did not appear to further potentiate the suppressive effects of TNFalpha.

CONCLUSION

TNFalpha suppresses both basal and glucose-stimulated insulin transcription and secretion in HIT-T15 cells, an effect that is enhanced significantly by high glucose. Leptin also independently inhibits basal and glucose-stimulated insulin secretion and transcription but does not modify TNFalpha effects. These effects might contribute to the abnormalities of glucose metabolism that characterize conditions of increased TNFalpha and/or leptin production.

Food-dependent androgen and cortisol secretion by a gastric inhibitory polypeptide-receptor expressive adrenocortical adenoma leading to hirsutism and subclinical Cushing's syndrome: in vivo and in vitro studies

Aberrant gastric inhibitory polypeptide (GIP) receptor expression in bilaterally hyperplastic adrenals or unilateral adrenal adenomas is a rare form of adrenal hyperfunction. So far, only few cases have been described. In all these cases, cortisol was the predominant steroid released in a food-dependent manner, leading to the development of non-ACTH-dependent Cushing's syndrome. In the present study, we describe a novel case of a GIP receptor-expressive adrenocortical adenomatous nodule, detected incidentally by computed tomography scanning in a 41-yr-old lady with hirsutism but no clinical signs of Cushing's syndrome, on physical examination. Hormonal investigations in morning fasting samples showed slightly elevated androgen levels, low-normal baseline cortisol, normal suppression of cortisol after dexamethasone administration, and ACTH levels that were not suppressed and did stimulate after CRH administration. The elevated urinary free cortisol excretion, in conjunction with an atypical cortisol diurnal rhythm, raised the possibility of an aberrant stimulation of cortisol production by the adrenal tumor. Further studies demonstrated food-dependent secretion of cortisol, which was abolished by prior octreotide administration. Notably, substantial amounts of adrenal androgens were also secreted after food consumption. Removal of the tumor resulted in undetectable cortisol and androgen levels that did not respond to food consumption. Histological examination of the excised tumor revealed an adrenocortical adenomatous nodule originating from the inner zona reticularis, consisting mainly of compact cells. A steroidogenic secretory pattern, indicating the concomitant release of adrenal androgens and cortisol, was also observed in vitro from tumor cells cultured in the presence of GIP. The in vitro secretory response to GIP was higher for the adrenal androgen DHEA, compared with cortisol. The expression of the GIP receptor in tumor cells, but not in the adjacent normal adrenal, was demonstrated by RT-PCR), using specific oligonucleotide probes for this receptor. In summary, we describe a patient with a GIP-expressive cortisol and androgen oversecreting adrenocortical nodule with the unusual presentation of hirsutism and not the typical clinical signs of Cushing's syndrome. It is of note that food intake in this patient provoked a substantial increase in both adrenal androgen and cortisol levels that, together with the histological appearance of this nodule, was compatible with a zona reticularis-derived tumor. Thus, aberrant expression of the GIP receptor does not exclusively involve cells of a zona fasciculata phenotype, as previously reported, but may also occur in other types of differentiated adrenocortical cells.

Expression of the long and short leptin receptor isoforms in peripheral blood mononuclear cells: implications for leptin's actions

Leptin, the adipocyte-derived hormone, is secreted into the blood and regulates body weight via its receptors in the hypothalamus. Leptin receptors are also present in many peripheral tissues implicating leptin in the regulation of other body functions, including reproduction, liver and enteric metabolism, hematopoiesis, and immunity. Four splice variants of the leptin receptor have been identified in humans: the long isoform that has full intracellular signaling capacity and 3 shorter isoforms that differ in the length of their cytoplasmic tail. Here, we report the quantification by reverse transcriptase-polymerase chain reaction (RT-PCR) of the relative expression levels of the 2 major leptin receptor splice variants, the long (OB-RL) and the shortest membrane bound variant (OB-RS) in mononuclear cells from peripheral blood of 15 healthy human subjects (9 women and 6 men), with a body mass index (BMI) that ranged from 19.7 to 41.6. Both OB-RL and OB-RS were coexpressed in all mRNAs tested. However, the expression of the short form (OB-RS), was on average 8-fold higher than the expression of the long form (OB-RL) (120.8 +/- 12.9 v 14.6 +/- 3.0 relative intensity units, P < .001). The predominance of the short splice variant over the long one was apparent in all samples and ranged from 4- to 27-fold. There was no significant difference in the expression of either isoform between men and women. However, the relative expression of both OB-RS and OB-RL isoforms was significantly lower in the overweight (BMI > 26), compared with the lean subjects (BMI < 25) (78.8 +/- 9.1 and 6.2 +/- 1.1 v148.8 +/- 14.4 and 18.9 +/- 4.0 relative intensity units, respectively, P < .03) and was inversely correlated with the BMI and plasma leptin levels (P < .01). In conclusion, the expression of OB-RS and OB-RL leptin receptor isoforms appears to be reduced in human peripheral blood mononuclear cells from obese individuals, with OB-RS remaining the predominant leptin receptor isoform. This might have implications for the bioavailability and/or action of circulating leptin not only on these cells, but also on other target tissues.

Mutations of the ACTH receptor gene in a new family with isolated glucocorticoid deficiency

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive disorder characterized by primary adrenocortical insufficiency, without mineralocorticoid deficiency. Mutations of the ACTH receptor gene have been reported in several families with IGD. We have amplified and directly sequenced the entire intronless ACTH receptor gene in a new family with IGD. The proband was found to be compound heterozygote for two different point mutations, one in each allele: (a) a substitution (360C>G) which changed neutral serine at position 120 in the apolar third transmembrane domain of the receptor to a positively charged arginine (S120R), probably disrupting the ligand-binding site; and (b) a substitution (761A>G) changing tyrosine at position 254 to cysteine (Y254C) in the third extracellular loop of the receptor protein, that also likely disrupts its structure and interferes with ligand binding. Each of the two mutations in the proband has previously been described in a different family, S120R in compound heterozygosity with a stop codon (R201X) and Y254C in homozygote form. Thus, in the absence of in vitro functional studies, our findings confirm the pathogenetic role of the S120R and Y254C mutants in the development of resistance to ACTH.