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.

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.

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.

High-dose oral dextromethorphan versus placebo in painful diabetic neuropathy and postherpetic neuralgia

N-methyl-D-aspartate (NMDA) receptor antagonists relieve neuropathic pain in animal models, but side effects of dissociative anesthetic channel blockers, such as ketamine, have discouraged clinical application. Based on the hypothesis that low-affinity NMDA channel blockers might have a better therapeutic ratio, we carried out two randomized, double-blind, crossover trials comparing six weeks of oral dextromethorphan to placebo in two groups, made up of 14 patients with painful distal symmetrical diabetic neuropathy and 18 with postherpetic neuralgia. Thirteen patients with each diagnosis completed the comparison. Dosage was titrated in each patient to the highest level reached without disrupting normal activities; mean doses were 381 mg/day in diabetics and 439 mg/day in postherpetic neuralgia patients. In diabetic neuropathy, dextromethorphan decreased pain by a mean of 24% (95% CI: 6% to 42%, p = 0.01), relative to placebo. In postherpetic neuralgia, dextromethorphan did not reduce pain (95% CI: 10% decrease in pain to 14% increase in pain, p = 0.72). Five of 31 patients who took dextromethorphan dropped out due to sedation or ataxia during dose escalation, but the remaining patients all reached a reasonably well-tolerated maintenance dose. We conclude that dextromethorphan or other low-affinity NMDA channel blockers may have promise in the treatment of painful diabetic neuropathy.

Chronic insomnia and activity of the stress system: a preliminary study

The aim of this study was to assess whether there is an association between chronic insomnia and the activity of the stress system. Fifteen young adult insomniacs (<40 years) were studied. After an adaptation night, each subject was recorded in the sleep laboratory for three consecutive nights. During this period, 24-hour urine specimens were collected for measurements of urinary free cortisol (UFC), catecholamines, and growth hormone (GH). The 24-hour UFC levels were positively correlated with total wake time (p=0.05). In addition, 24-hour urinary levels of catecholamine metabolites, DHPG, and DOPAC were positively correlated with percent stage 1 sleep (p<0.05) and wake time after sleep onset (WTASO) (p<0.05). Norepinephrine tended to correlate positively with percent stage 1 sleep (p=0.063) and WTASO (p=0.074), and negatively with percent slow-wave sleep (p=0.059). Twenty-four-hour urinary GH excretion was detectable in only three insomniacs, two of whom had low indices of sleep disturbance. We conclude that, in chronic insomnia, the activity of both limbs of the stress system (i.e., the HPA axis and the sympathetic system) relates positively to the degree of objective sleep disturbance.

The prevalence of foot ulceration and its correlates in type 2 diabetic patients: a population-based study

The prevalence of peripheral neuropathy, peripheral vascular disease, and foot ulceration in Type 2 diabetic patients in the community were determined in a community-based study. Eight hundred and eleven subjects (404 male, 407 female, mean age 65.4 (range 34-90) years, diabetes duration 7.4 (0-50) years) from 37 general practices in three UK cities were studied. Neuropathy was diagnosed clinically using modified neuropathy disability scores which were ascertained using structured interviews and clinical examinations by one observer in each city. Peripheral vascular disease was diagnosed if a history of revascularization was present or > or = 2 foot pulses were absent. History of current or previous foot ulceration was recorded. The prevalence of neuropathy was 41.6% (95% confidence limits 38.3-44.9%) and the prevalence of PVD, 11% (9.1-13.7%). Forty-eight percent of neuropathic patients reported significant neuropathic symptoms. Forty-three patients (5.3% (3.8-6.8%)) had current or past foot ulcers; 20 of these were pure neuropathic ulcers, 13 neuroischaemic, 5 pure vascular, and 5 were unclassified. Multiple logistic regression showed history of amputation, neuropathy disability score, and peripheral vascular disease to be significantly associated with foot ulceration after adjusting for age and diabetes duration. A substantial proportion of Type 2 diabetic patients, often elderly patients who do not attend hospitals, suffered from peripheral neuropathy and peripheral vascular disease. These patients are at risk of foot ulceration and may benefit from preventive footcare.

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.

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.

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.

Circulating tumor necrosis factor alpha concentrations are higher in abdominal versus peripheral obesity

Fat tissue is a significant source of endogenous tumor necrosis factor alpha (TNFalpha), the pluripotent cytokine that plays an important role as a mediator of the peripheral insulin resistance found in obesity. The majority of evidence for this role of TNFalpha is from studies in animal models of obesity. To explore further the role of TNFalpha in the pathogenesis of obesity-related insulin resistance in humans, we compared plasma levels of TNFalpha and the other main endocrine cytokine, interleukin-6 ([IL-6] both measured by enzyme-linked immunosorbent assay), in 26 obese women (body mass index [BMI] > 30 kg/m2) and 13 female controls (BMI < 26 kg/m2) without a history of recent or active infection. Glucose and insulin levels were measured at 0, 1, and 2 hours after a 75-g oral glucose load. There was no significant difference in plasma TNFalpha or IL-6 levels between obese and non-obese subjects overall (2.10 +/- 0.19 v 1.65 +/- 0.18 pg/mL and 2.06 +/- 0.29 v 1.50 +/- 0.17 pg/mL, respectively). However, TNFalpha levels were significantly elevated in obese subjects with a 2-hour glucose level more than 140 mg/dL (n = 8) compared with the other obese subjects (n = 18) and the non-obese controls (2.88 +/- 0.46 v 1.75 +/- 0.10 and 1.65 +/- 0.18 pg/mL, respectively, P < .01). Furthermore, the TNFalpha level correlated significantly with the waist to hip ratio ([WHR] r = .53, P < .01) and fasting and post-oral glucose tolerance test (OGTT) insulin levels (r = .47, P < .02), but not with the BMI, and was higher in obese women with a WHR more than 0.90 (n = 14) in comparison to those with a WHR less than 0.90 (n = 12, 2.47 +/- 0.29 v 1.66 +/- 0.18 pg/mL, respectively, P < .03). The corresponding plasma leptin level was significantly higher in obese women versus the control group (41.6 +/- 2.5 v22.3 +/- 2.9 ng/mL, P < .001) and was related to the BMI (r = .60, P < .01) but not to TNFalpha or the WHR. There were no significant differences in the corresponding IL-6 concentration between groups, and IL-6 did not correlate with TNFalpha, leptin, BMI, WHR, or insulin levels. In conclusion, circulating TNFalpha levels are higher in abdominal obesity compared with peripheral obesity, and may contribute to the insulin resistance that more commonly complicates the former pattern of fat distribution.

Dose-dependent effects of recombinant human interleukin-6 on glucose regulation

Inflammatory cytokines have metabolic actions that probably contribute to the general adaptation of the organism during infectious or inflammatory stress. To examine the effects of interleukin 6 (IL-6), the main circulating cytokine, on glucose metabolism in man, we performed dose-response studies of recombinant human IL-6 in normal volunteers. Increasing single doses of IL-6 (0.1, 0.3, 1.0, 3.0, and 10.0 mg/Kg BW) were injected sc in 15 healthy male volunteers (3 in each dose) after a 12-h fast. All IL-6 doses were tolerated well and produced no significant adverse effects. We measured the circulating levels of glucose, insulin, C-peptide, and glucagon at baseline and half-hourly over 4 h after the IL-6 injection. Mean peak plasma levels of IL-6 were achieved between 120 and 240 min and were 8, 22, 65, 290, and 4050 pg/mL, respectively, for the 5 doses. After administration of the 2 smaller IL-6 doses, we observed no significant changes in plasma glucose levels, which, because of continued fasting, decreased slightly over time. By 60 min after the 3 higher IL-6 doses, however, the decline in fasting blood glucose was arrested, and glucose levels increased in a dose-dependent fashion. The concurrent levels of plasma insulin and C-peptide were not affected by any IL-6 dose. In contrast, IL-6 caused significant increases in plasma glucagon levels, which peaked between 120 and 150 min after the IL-6 injection. In conclusion, sc IL-6 administration induced dose-dependent increases in fasting blood glucose, probably by stimulating glucagon release and other counteregulatory hormones and/or by inducing peripheral resistance to insulin action.

Dose effects of recombinant human interleukin-6 on pituitary hormone secretion and energy expenditure

Interleukin-6 (IL-6), the main circulating cytokine, is putatively a major mediator of the effects of the immune system on several endocrine axes and intermediate metabolism. We performed dose-response studies of recombinant human IL-6 on pituitary hormone secretion in 15 healthy male volunteers, using 5 single, escalating subcutaneous doses of IL-6 (0.1, 0.3, 1.0, 3.0 and 10.0 micrograms/kg body weight), each in 3 volunteers. We measured resting metabolic rate (RMR) with indirect calorimetry and plasma anterior pituitary hormones and vasopressin (AVP) at baseline and half-hourly over 4 h after the injection. All doses examined were tolerated well and produced no significant adverse effects. Dose-dependent RMR increases were observed in response to the 3.0- and 10.0-microgram/kg doses of IL-6, beginning at 60 min and slowly peaking between 180 and 240 min. Plasma adrenocorticotropic-hormone concentrations increased dramatically and dose-dependently in all the patients who received the 3.0- and 10.0-microgram/kg doses of IL-6, respectively, peaking to 150 and 255 pg/ml at 60 min, and slowly returning to normal by 4 h. Corresponding plasma cortisol levels peaked dose-dependently between 90 and 150 min, but remained elevated throughout the sampling period. In contrast, the growth hormone (GH) dose-response was bell-shaped, with maximum (approximately 100-fold) stimulation achieved by 3.0 micrograms/kg IL-6. Prolactin (PRL) showed a similar but less pronounced response pattern. Thyroid-stimulating hormone (TSH) dose-dependently and progressively decreased over the 240 min, while gonadotropins showed no clear-cut changes. In conclusion, subcutaneous IL-6 administration induced synchronized dose-dependent increases in the RMR and hypothalamic-pituitary-adrenal axis activity, suggesting that hypothalamic corticotropin-releasing hormone may mediate both of these functions in humans. IL-6 also acutely stimulated GH and PRL secretion and suppressed TSH secretion. The dose of 3.0 micrograms/kg could be used safely in the study of patients with disturbances of the hypothalamic-pituitary unit or of thermogenesis.

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.

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.

The maternal hypothalamic-pituitary-adrenal axis in the third trimester of human pregnancy

OBJECTIVE

The third trimester of pregnancy is characterized by a mildly hyperactive hypothalamic-pituitary-adrenal (HPA) axis, possibly driven by elevated circulating levels of corticotrophin releasing hormone (CRH) of placental origin. In-vitro studies have demonstrated that glucocorticoids and oestrogen stimulate while progesterone inhibits the expression of CRH mRNA and/or protein, suggesting that several potential interactions between the placenta and the HPA axis may exist.

DESIGN AND PATIENTS

To investigate the detailed pattern of circulating immunoreactive (ir) CRH, ACTH, cortisol, oestradiol and progesterone during the third trimester of pregnancy, plasma samples were drawn serially every 30 minutes from 22 healthy pregnant women (age 32.0 +/- 1.1 years, mean +/- SE) between the 34th and 36th week of gestation. Ten women had plasma samples drawn between 0800 h and 2000 h (daytime group), and 12 between 2000 h and 0800 h (night-time group). The hormone concentrations obtained were analysed for pulsatility by the Detect program, for detection of circadian rhythmicity by comparison between the first and second 6-hour periods within each group by Student's t-test, and for time-dependent correlations by cross-correlation analysis.

RESULTS

All five hormones were secreted in a pulsatile fashion. There was no apparent circadian rhythm of CRH or oestradiol secretion, whereas there was a clear circadian rhythm in plasma ACTH, cortisol and progesterone secretion, with the latter in reverse phase (P < 0.05). No significant correlations were observed between CRH and ACTH, whereas, as expected, ACTH and cortisol concentrations were strongly correlated with each other over time (r = 0.32 and 0.70 at lag time 30 minutes for the daytime and night-time groups, respectively), with ACTH leading cortisol. A weak positive correlation was observed between CRH and cortisol concentrations for the night-time group at lag time 0 minute, suggesting that the latter may have a positive effect on the former in vivo.

CONCLUSIONS

These data suggest that placental CRH, although pulsatile, drives quantitatively the maternal HPA axis in the third trimester of pregnancy in a non-circadian, non-pulsatile fashion. The maternal HPA axis is probably driven in a circadian and pulsatile fashion by another major ACTH secretagogue, most likely AVP of parvocellular paraventricular nucleus origin.

Hereditary isolated glucocorticoid deficiency is associated with abnormalities of the adrenocorticotropin receptor gene

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive disorder characterized by progressive primary adrenal insufficiency, without mineralocorticoid deficiency. The cDNA and gene of the human ACTH receptor were recently cloned. The gene encodes a 297-amino acid protein that belongs to the G protein-coupled superfamily of membrane receptors. We hypothesized that the ACTH receptor gene might be defective in IGD. To examine this, we studied its genomic structure by PCR and direct sequencing in a 5-yr-old proband with the disease, his parents, and grandparents. The proband was a compound heterozygote for two different point mutations, one in each allele: (a) a substitution (C-->T), also found in one allele of the mother and maternal grandmother, which introduced a premature stop codon (TGA) at position 201 of the protein; this mutant receptor lacks its entire carboxy-terminal third and, if expressed, should be unable to transduce the signal; and (b) a substitution (C-->G), also found in one of the paternal alleles, which changed neutral serine120 in the apolar third transmembrane domain of the receptor to a positively charged arginine, probably disrupting the ligand-binding site. Standard ovine corticotropin releasing hormone (oCRH) test in the heterozygote parents and maternal grandmother revealed exaggerated and prolonged ACTH responses, suggestive of subclinical resistance to ACTH. We conclude that IGD in this family appears to be due to defects of the ACTH receptor gene. The oCRH test appears to be useful in ascertaining heterozygosity in this syndrome.

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.

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.

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.

Plasma metadrenalines: do they provide useful information about sympatho-adrenal function and catecholamine metabolism?

1. The clinical utility of plasma metadrenalines for examination of sympatho-adrenal function and catecholamine metabolism was assessed from plasma measurements of these metabolites in a number of clinical conditions (hypertension, cardiac failure, bilateral adrenalectomy and X-chromosomal deletions of the gene for monoamine oxidase), and before and during activation of sympathetic outflow or infusions of noradrenaline and adrenaline. 2. Plasma concentrations of normetadrenaline were less than 25% of those of noradrenaline, concentrations of metadrenaline and adrenaline were similar and those of sulphate-conjugated metadrenalines were 20- to 30-fold higher than free metadrenalines. Hypertensive patients had elevated plasma concentrations of adrenaline, noradrenaline and conjugated but not free metadrenalines. Cardiac failure patients had 2- to 4-fold increases in plasma noradrenaline and free and conjugated normetadrenaline. Adrenalectomy resulted in undetectable plasma concentrations of adrenaline, 91-97% decreases in free and conjugated metadrenaline and a 40% decrease in normetadrenaline relative to noradrenaline. Patients with X-chromosomal deletions of the gene for monoamine oxidase had 6- and 16-fold increases in plasma free and conjugated normetadrenaline and 2- and 4-fold increases in free and conjugated metadrenaline. 3. Infusion of catecholamines increased plasma concentrations of free metadrenalines by less than 6% of increases in precursor amines, indicating that most plasma normetadrenaline (84%) and metadrenaline (90%) is derived from metabolism of catecholamines before their entry into the circulation. Considerable O-methylation of catecholamines within the adrenals explains why sympatho-adrenal activation resulted in smaller proportional increases in plasma metadrenalines than catecholamines. 4. Plasma metadrenalines provide supplementary information about sympatho-adrenal activity to that provided by catecholamines, but are more useful for examination of the extraneuronal inactivation of catecholamines, particularly detection of neurochemical phenotypes in genetic disorders of catecholamine metabolism. Significant formation of metadrenalines within chromaffin tissue explains why measurements of plasma metadrenalines provide an extraordinarily sensitive method for diagnosis of phaeochromocytoma.

Acute and delayed effects of a single-dose injection of interleukin-6 on thyroid function in healthy humans

Interleukin-6 (IL-6) is produced in response to inflammatory and noninflammatory stress and acts as the principal regulator of the acute-phase protein response. IL-6 stimulates the hypothalamic-pituitary-adrenal axis and may be involved in the thyroid function abnormalities observed in nonthyroidal illness (NTI). This study examined the effects of single-dose IL-6 (3 microg/kg subcutaneously [s.c.]) in healthy human subjects: 19 received IL-6 and 13 received control saline injection. The dose of IL-6 was chosen on the basis of previous studies indicating that the peak IL-6 level after injection reaches concentrations observed with major stress such as abdominal surgery. Plasma levels of thyrotropin (TSH), free thyroxine (FT4), total T4, 3,5-3'-L-triiodothyronine (T3), 3,3'-5'-L-triiodothyronine or reverse T3 (rT3), and thyroxine-binding globulin (TBG) were measured over a 4-hour period and 24 hours after IL-6 injection. Plasma TSH levels were 27% lower 240 minutes after IL-6 relative to control levels (0.93 +/- 0.10 v 1.28 +/- 0.18 mIU/mL, P = .001), but recovered by 24 hours. Plasma FT4 was elevated at 240 minutes compared with the controls (1.16 +/- 0.04 v 1.03 +/- 0.03 ng/dL, P = .0002). T4 levels were also elevated at 240 minutes (7.8 +/- 0.36 v 7.05 +/- 0.37 microg/dL, P = .0003). TBG levels were not significantly changed at this time point. At 24 hours, T3 levels were 19% lower than the control values (87.6 +/- 5.1 v 108.5 +/- 5.4 ng/dL, P = .0002); plasma rT3 levels were elevated by 21% compared with control levels (30.6 +/- 1.7 v 24.3 +/- 1.3 ng/dL, P = .002), while FT4 levels returned to normal. The changes in T3/rT3 levels were reminiscent of the pattern observed in NTI that may be due to inhibition of type-1 5'-deiodinase. Cortisol levels were greatly elevated after IL-6 compared with control values; peak levels were observed 120 minutes after IL-6 injection (28.7 +/- 1.6 v 9.5 +/- 1.0 ng/dL, P < .0001). This elevation in cortisol may have contributed to the suppression of TSH levels and inhibition of type-1 5'-deiodinase activity. Alternatively, IL-6 may have suppressed TSH secretion via a direct suprapituitary action. The elevation of T4 and FT4 levels may have been due to inhibition of T4 degradation at the liver and/or by direct action of IL-6 on the thyroid gland. These findings demonstrate the potent effects of IL-6 on thyroid hormone metabolism in healthy individuals, and suggest that IL-6 may act directly or indirectly at two or more sites on thyroid hormone secretion and metabolism.

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.

Endocrine and metabolic evaluation of human immunodeficiency virus-infected patients with evidence of protease inhibitor-associated lipodystrophy

Multidrug antiretroviral regimens that include human immunodeficiency virus-1 (HIV-1) protease inhibitors are associated with distinct lipodystrophy, hypertriglyceridemia, hyperinsulinemia, and deposition of visceral abdominal adipose tissue. To determine whether these findings are related to abnormalities of adrenal function, we compared the hypothalamic-pituitary-adrenal axes of HIV-positive patients who had evidence of protease inhibitor-associated lipodystrophy (PIAL), control volunteers (CON), and patients with Cushing's syndrome (CS). To elucidate the metabolic consequences of the observed lipodystrophy, we measured basal serum lipids and compared glucose and insulin concentrations during an oral glucose tolerance test. Spontaneous plasma cortisol showed normal diurnal variation in PIAL. Cortisol levels were similar in CON and PIAL, and levels in these groups were less than those in CS at all times of the night or day (P < 0.005). Ovine CRH-stimulated morning plasma cortisol levels were similar in PIAL and CON. ACTH was significantly greater in PIAL than CON (P < 0.05) at 0, 15, and 30 min after CRH stimulation. Urinary free cortisol in PIAL (mean +/- SD, 76 +/- 51 nmol/day) was significant lower than those in CON (165 +/- 64 nmol/day; P < 0.001) and CS (1715 +/- 1203 nmol/day; P < 0.001). However, 17-hydroxycorticosteroid excretion was significantly greater in PIAL (43 +/- 23 micromol/day) than in CON (17 +/- 8 micromol/day; P < 0.001), although lower than that in CS (74 +/- 47 micromol/day; P < 0.01). Scatchard analysis revealed normal glucocorticoid receptor number and affinity in PIAL. Serum triglycerides were significantly greater in PIAL (6.57 +/- 5.63 mmol/L) than in CS (1.78 +/- 0.83 mmol/L; P < 0.001) or CON (1.36 +/- 0.84 mmol/L; P < 0.001). Although triglyceride levels were significantly correlated with body mass index for CON and CS, these were not correlated for PIAL. During an oral glucose tolerance test, similar glucose and insulin values were found in PIAL and CS that were greater (P < 0.05) than CON values at 30, 60, 90, and 120 min. We conclude that the lipodystrophy associated with use of HIV-1 protease inhibitors is a syndrome of increased intraabdominal adiposity with concomitant dyslipidemia and insulin resistance, but without total body weight gain and is distinct from any known form of hypercortisolism. Although urinary cortisol disposition seems to be altered in HIV-infected patients who are being treated with multidrug regimens that include protease inhibitors, the decreased free cortisol and increased 17-hydroxycorticosteroid excretion appear to be unlikely explanations for the observed lipodystrophy. The cause remains to be elucidated.