Ghrelin inhibits autonomic function in healthy controls, but has no effect on obese and vagotomized subjects

OBJECTIVE

Ghrelin inhibits sympathetic nervous system (SNS) activity in rodents. We studied the effect of ghrelin on healthy humans, in obesity and in vagotomized subjects.

DESIGN

Randomized, double-blinded, placebo-controlled crossover.

SUBJECTS

Seven lean [mean body mass index (BMI) 23·6 ± 0·9 kg/m(2) ], seven morbidly obese (mean BMI 50·9 ± 4·4 kg/m(2) ) and seven post-gastrectomy subjects (mean BMI 22·0 ± 1·1 kg/m(2) ).

MEASUREMENTS

Subjects were randomized to intravenous ghrelin (5 pmol/kg/min) or saline over 270 min. Subjects had a fixed calorie meal and a free choice buffet during the infusion. Heart rate variability (HRV) was measured. Total power (TP) represents overall autonomic function, low-frequency (LF) power represents sympathetic and parasympathetic activity, and high-frequency (HF) power represents parasympathetic activity. Very low (VLO) frequency represents the frequency band associated with thermogenesis.

RESULTS

Preliminary anova analysis, looking at all three subject groups together, showed that ghrelin had an overall highly significant inhibitory effect on TP (P = 0·001), HF power (P = 0·04), VLO power (P = 0·03) and no effect on LF (P = 0·07). Further subset analysis revealed that ghrelin had a significant effect on TP (P = 0·03), borderline effect on LF power (P = 0·06) and no effect on HF power (P = 0·1) in healthy controls. By contrast in obese subjects, ghrelin had no effect on TP (P = 0·3), LF (P = 0·5) and HF (P = 0·06) and also no effect in the vagotomized subjects on TP (P = 0·7), LF (P = 0·7) and HF (P = 0·9). Ghrelin had no effect on the LF/HF ratio.

CONCLUSIONS

Ghrelin inhibits SNS activity in healthy controls with a moderate effect on parasympathetic nervous system activity but had no effect on obese subjects. Vagotomized subjects also did not respond to ghrelin, suggesting the vagus nerve is important for the effects of peripheral ghrelin on the SNS.

The influence of growth hormone replacement on peripheral inflammatory and cardiovascular risk markers in adults with severe growth hormone deficiency

BACKGROUND

Adult GHD syndrome is associated with clustering of adverse cardiovascular (CV) risk factors such as abnormal body composition, dyslipidemia, insulin resistance and abnormal haemostatic factors. There is a wealth of evidence linking CV events with elevated levels of inflammatory markers (hs-CRP and IL-6) in the general population; however data on their abnormalities in GHD and specially the effects of GH replacement (GHR) on these inflammatory markers are limited.

OBJECTIVE

To study the effects of GHR on inflammatory markers, glucose homeostasis and body composition in a cohort of adults with recently diagnosed severe GHD due to hypothalamic pituitary disease.

DESIGN

Fifteen hypopituitary adults (11 males, mean age 48.5 years) with recently diagnosed, severe GHD were recruited. Patients received GHR (in addition to other pituitary hormone replacements) titrated to clinical response and to normalize age and gender adjusted IGF-1 levels. Weight, waist hip ratio (WHR), body composition, fasting plasma glucose and insulin, insulin resistance index (HOMA-IR), fasting serum lipid levels, hs-CRP, IL-6 and TNF-alpha were measured at baseline and following a minimum 6 months of stable maintenance GHR.

RESULTS

GHR resulted in a physiological increase in IGF-1 SDS [median -0.6 to +0.39, P<0.0001], improved quality of life (mean pre-treatment AGHDA score 16 vs. post-treatment score 7, P<0.0001) and reduction in WHR (0.94 vs. 0.92, P=0.01). There were no significant changes in body weight and composition. Levels of hs-CRP (log transformed, mean (SD)) were significantly reduced following GHR (pre 1.21 (0.9) vs. post 0.27 (0.9), P<0.0001) but TNF-alpha and IL-6 levels remained unchanged. Fasting glucose (mmol/L) [4.6 (0.1) vs. 5.1 (0.1), P=0.003], fasting insulin (muU/mL) [9.4 (8.1) vs. 12.1 (9.2), P=0.03] and HOMA-IR [1.2 (1.0) vs. 1.5 (1.1) P=0.02] (all pre-GHR vs. post-GHR and mean (SD)) significantly increased following GHR indicating increased insulin resistance. Significant improvements were noted in fasting LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels following GHR [3.4 (0.9) vs. 2.9 (0.7), P=0.03 and 1.2 (0.2) vs. 1.3 (0.2), P=0.02, respectively] (all pre-GHR vs. post-GHR and mean (SD)). Levels of total cholesterol and triglycerides did not change following GHR.

CONCLUSIONS

Physiological GHR for at least 6 months in hypopituitary adults with recently diagnosed severe GHD resulted in favourable changes in hs-CRP, WHR, fasting LDL-C and HDL-C levels all of which are recognised CV risk markers. However, there remains a high prevalence of obesity in this population and given the worsening of insulin sensitivity in the short term with GHR, monitoring and aggressive treatment of established CV risk factors is essential to reduce premature atherosclerotic CVD in this patient population.

Improvement in the care of multiple endocrine neoplasia type 1 through a regional multidisciplinary clinic

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is associated with significant morbidity and mortality. Timely detection of MEN1 kindred, together with treatment of associated tumours, results in an improved outcome. We describe how the development of a dedicated multidisciplinary MEN clinic has improved the diagnosis and treatment of MEN1-associated endocrinopathies.

DESIGN AND PATIENTS

A dedicated MEN clinic was developed at Aintree University Hospital, Liverpool in 2002 for patients living in Merseyside, Cheshire and North Wales. The multidisciplinary approach adopted, aimed to improve communication and continuity of care. Patients see all clinicians involved in their care (Consultant Endocrinologist, Paediatrician, Clinical Geneticist and Endocrine Surgeon) simultaneously, allowing for a unified, clear approach and a reduction in unnecessary attendances. The clinicians adopt a proactive approach to tracing the relatives of patients, with the aim of identifying kindred with previously asymptomatic disease.

RESULTS

In 2002, 16 patients from 5 families were diagnosed clinically with MEN1. Twenty MEN1-associated endocrinopathies had been diagnosed and 21 surgical procedures had been performed. By the end of 2008, 45 patients from 15 families had been identified, with 83 endocrinopathies diagnosed and 50 surgical procedures performed. Ninety-four known relatives are awaiting screening for MEN1.

CONCLUSION

The successful identification of patients with MEN1 has resulted in an exponential increase in the number of patients attending the clinic. As relatives undergo screening, the diagnosis of MEN is likely to increase. The ever increasing numbers of patients requiring screening, surveillance and treatment has implications in the planning of future service provision.

Type 2 diabetes and cardiovascular disease in polycystic ovary syndrome: what are the risks and can they be reduced?

Polycystic ovary syndrome (PCOS) is a risk factor for Type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD), but these risks are poorly defined. This study aimed to evaluate the evidence for these risks and whether screening and risk reduction are feasible. Medline reviews and data quality analysis were used using standard tools. Results showed that (i) polycystic ovary syndrome is a risk factor forT2DM but the magnitude of risk is uncertain, (ii) fasting plasma glucose is an inadequate screening test forT2DM in this population and the oral glucose tolerance test is superior, (iii) the identification of women with PCOS for diabetes screening is constrained by current diagnostic criteria for PCOS; however, women with oligomenorrhoea and those with diagnosed PCOS and obesity or a family history of T2DM are at highest risk, (iv) risk factors for T2DM are improved by weight loss interventions and by metformin. However, no studies have determined whether T2DM incidence is reduced, (v) polycystic ovary syndrome is associated with cardiovascular disease (CVD) risk factors but data on CVD incidence are weak, (vi) risk factors for CVD are improved by the same interventions and statins and (vi) no studies have evaluated whether CVD incidence is reduced. While PCOS has important metabolic associations, and short-term interventions reduce risk factors for T2DM and CVD, data on prevalence and incidence of T2DM and particularly CVD are poor. There is a need for a clear definition of PCOS, for diabetes screening protocols and for long-term studies to determine whether risks can be reduced.

The adipokine zinc-alpha2-glycoprotein (ZAG) is downregulated with fat mass expansion in obesity

INTRODUCTION

Zinc-alpha2-glycoprotein (ZAG) is a novel adipokine, which may act locally to influence adipocyte metabolism. This study assessed the effect of increased adiposity on ZAG expression in adipose tissue in human subjects. The study also examined the association between ZAG and adiponectin expression in human adipose tissue, and whether ZAG modulates adiponectin secretion by human adipocytes.

METHODS

Adipose tissue (visceral and subcutaneous) was collected from human subjects with a wide range of BMIs. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were used for in vitro studies. ZAG mRNA levels were quantified by real-time PCR and protein by Western blotting.

RESULTS

In human subjects, ZAG mRNA level was negatively correlated with BMI (r = -0.61, P < 0.001, n = 23, visceral; r = -0.6, P < 0.05, n = 14, subcutaneous) and fat mass (r = -0.62, P < 0.01, visceral; r = -0.6, P < 0.05, subcutaneous). Negative associations were also found between ZAG mRNA and insulin resistance parameters including plasma insulin (r = -0.65, P < 0.001, visceral; r = -0.55, P < 0.05, subcutaneous) and homeostasis model of insulin resistance (HOMA-IR) (r = -0.65, P < 0.001, visceral; r = -0.52, P = 0.055, subcutaneous), and C reactive protein (CRP) (r = -0.46, P < 0.05, visceral; r = -0.53, P < 0.05, subcutaneous). However, ZAG mRNA was positively correlated with adiponectin (r = 0.5, P < 0.05, visceral; r = 0.82, P < 0.001, subcutaneous) but negatively associated with leptin mRNA (r = -0.42, P < 0.05, visceral; r = -0.54, P < 0.05, subcutaneous). ZAG secretion by differentiated human adipocytes was abundant. Addition of recombinant ZAG stimulated adiponectin release from human adipocytes.

CONCLUSION

ZAG gene expression in adipose tissue is downregulated with increased adiposity and circulating insulin. ZAG mRNA is positively correlated with adiponectin mRNA, and ZAG enhances adiponectin production by human adipocytes. We suggest that ZAG is linked to obesity and obesity-related insulin resistance.

Plasma obestatin levels are lower in obese and post-gastrectomy subjects, but do not change in response to a meal

OBJECTIVE

To investigate a potential role for obestatin in humans by examining response to a fixed energy meal.

CONTEXT

A new anorectic peptide hormone, obestatin has recently been isolated from rat stomach. The significance of this peptide in humans is unknown.

STUDY DESIGN

Case-control study.

SETTING

Hospital-based study.

PATIENTS

Nine healthy controls, nine morbidly obese subjects and eight post-gastrectomy subjects.

INTERVENTION

Subjects attended after an overnight fast and were given a fixed energy meal (1550 kJ).

MAIN OUTCOME MEASURE

The response of obestatin to a meal in the different groups.

RESULTS

Fasting obestatin was significantly lower in obese subjects as compared to lean subjects (27.8+/-4 vs 17.2+/-2 pg/ml, P=0.03). Obestatin was also decreased in gastrectomy subjects but this did not reach statistical significance (27.8+/-4 vs 21.9+/-3 pg/ml, P=0.3). Obestatin did not change significantly from baseline in response to the meal. Lean and obese subjects had a similar obestatin/ghrelin ratio (0.04+/-0.003 vs 0.05+/-0.009, P=0.32), but this was higher in the gastrectomy group (0.04+/-0.003 vs 0.1+/-0.01, P<0.001).

CONCLUSIONS

Obestatin does not vary significantly with a fixed energy meal, but is significantly lower in morbidly obese subjects as compared to lean subjects supporting a possible role for obestatin in long-term body weight regulation. Obestatin tended to be lower in gastrectomy subjects and their obestatin/ghrelin ratio differed from healthy controls. Hence, the expression of obestatin is altered following gastrectomy, suggesting other sites outside the stomach may also secrete obestatin.

Diabetes in a high secure hospital

AIMS

To determine the prevalence of diabetes mellitus and its possible causes and to assess its control in a high secure hospital.

METHODS

A cross sectional survey and a prospective cohort study were conducted. The cross sectional survey included 408 patients admitted under the Mental Health Act, and the prospective study included 22 patients with known diabetes followed up for 24 months. The outcome measures evaluated were drug treatment, status of microvascular and macrovascular complications, glycated haemoglobin, and body mass index.

RESULTS

In the cross sectional survey, 35 out of 408 patients (8.6%; 95% confidence interval 5.9% to 11.3%) had known diabetes, and all of these had type 2 diabetes. Obesity, cigarette smoking, schizophrenia, and antipsychotic drug use were frequent, and weight gain was common after hospital admission. Glycaemic control was variable, and, although a majority of patients were above recommended treatment targets, control remained stable over the follow up period.

CONCLUSIONS

Type 2 diabetes was common in this hospital. Both its prevalence and the suboptimal glycaemic control in some patients probably relate to sedentary life, dietary factors, smoking, and perhaps widespread use of antipsychotic drugs. However, regular multidisciplinary input enabled most patients to maintain relatively stable glycaemic control, with good control of blood pressure and lipids, at levels similar to those seen in community and hospital diabetic clinics. Further modification of lifestyle risk factors is probably needed to reduce the prevalence and impact of diabetes in this patient group.

Current status of bariatric surgery in the treatment of type 2 diabetes

Bariatric surgery (from the Greek words baros meaning 'weight' and iatrikos 'the art of healing') is a rapidly evolving branch of surgical science. The aim is to induce major weight loss in those whose obesity places them at high risk of serious health problems. In an attempt to balance the risks of surgery against the benefits of weight loss, bariatric operations are currently performed only in the morbidly obese, or those with a body mass index (BMI) > 35 kgm(-2) who already have developed comorbidity such as type 2 diabetes. Although weight loss is beneficial for obese patients with diabetes, current medical treatment for obesity is difficult. In contrast, observational studies show a major impact of bariatric surgery on diabetes, raising the question whether this approach should be used more widely to treat diabetes in obese patients? If bariatric surgery were shown to be the best way to treat diabetes in obese subjects the implications for health services would be wide-ranging. Bariatric surgery leads to withdrawal of diabetic treatment in about 60% or more of patients, and reductions of therapy for many others. Although data on bariatric surgery in subjects with diabetes are provocative, most studies have been uncontrolled or flawed in other ways. Most importantly, bariatric surgery has not yet been compared against standard medical treatment for diabetes in randomized controlled trials with diabetes-specific endpoints in all relevant patient groups. Potential indications for bariatric surgery are discussed, and the unanswered questions that need to be addressed by clinical trials are summarized. Although small numbers of patients may be interested in bariatric surgery for type 2 diabetes, current data are insufficient to endorse its wide scale use for this indication. Until essential studies are undertaken the role and economics of bariatric surgery in the diabetic clinic will remain uncertain.

Hypothalamic obesity in humans: what do we know and what can be done?

Obesity is a common sequel to tumours of the hypothalamic region and their treatment with surgery and radiotherapy. The prevalence of hypothalamic obesity has been underestimated because it may take some years to develop, and the problem has been under-recognized by physicians. Weight gain results from damage to the ventromedial hypothalamus which leads, variously, to hyperphagia, a low metabolic rate, autonomic imbalance, growth hormone (GH) deficiency and various other problems that contribute to weight gain. However, with the exception of GH replacement, few clinical trials have evaluated significant numbers of patients and so the roles of various behavioural, dietary, pharmacological and obesity surgery approaches are controversial. Sufficient knowledge exists to identify those at high risk of hypothalamic obesity so that weight gain prevention approaches can be offered. In those who are already obese, we propose that the principal causal mechanisms in individual patients should be considered as a basis for guiding clinical management.

beta-Adrenergic regulation of IL-6 release from adipose tissue: in vivo and in vitro studies

Circulating IL-6 levels are elevated in obesity. Although IL-6 is expressed in adipose tissue, neither its regulation nor cell of origin is well characterized. Here we investigated the beta-adrenergic regulation of IL-6 release in a combination of studies on humans and animals in vivo and cultured adipocytes in vitro. Human in vivo study: Human volunteers were infused with isoproterenol, norepinephrine, or saline [4 M:4F; mean (SD) age 35.5 (5.8) yr; body mass index 24.6 (4.2) kg/m(-2)]. Plasma IL-6 levels increased during a 3-h infusion of isoproterenol (P = 0.01) and fell 2 h post infusion (P = 0.05). IL-6 levels did not change significantly with either norepinephrine or saline. Murine in vivo study: C57BL6/J male mice were injected ip with dobutamine (beta(1) agonist), clenbuterol (beta(2)), CL316243 (beta(3)), or saline placebo. Plasma IL-6 levels at 3 h were increased by clenbuterol (P = 0.02) and CL316243 (P = 0.02) but not dobutamine (P = 0.51), compared with placebo.

IN VITRO STUDIES

In human peripheral blood cells, lipopolysaccharide treatment enhanced secretion of IL-6 (vs. controls; P < 0.001), whereas isoproterenol inhibited IL-6 secretion (P = 0.012) and norepinephrine had no significant effect. In contrast, isolated human adipocytes and differentiated 3T3F442A adipocytes all rapidly secreted IL-6 in response to adrenergic agonists (P < 0.01, compared with untreated cells). We conclude that beta 2/beta 3 adrenoceptor stimulation on adipocytes, rather than macrophages, may be responsible for the increases in plasma IL-6 concentrations observed during sympathetic activation and in obesity.

A defect in the regional deposition of adipose tissue (partial lipodystrophy) is encoded by a gene at chromosome 1q

Partial lipodystrophy (PLD), also known as "Dunnigan-Kobberling syndrome," is transmitted as a highly penetrant autosomal dominant disorder that is characterized by a dramatic absence of adipose tissue in the limbs and trunk, more evident in females than in males. In contrast, fat is retained on the face, in retro-orbital space, and at periserous sites. Associated metabolic abnormalities, including insulin resistance, hyperinsulinemia, and dyslipidemia, are referred to as "metabolic syndrome X" (Reaven 1988). Despite the intense interest in the genetic determinants underlying fat deposition, the genes involved in the lipodystrophic syndromes have not been identified. We ascertained two multigeneration families, with a combined total of 18 individuals with PLD, and performed a genomewide search. We obtained conclusive evidence for linkage of the PLD locus to microsatellite markers on chromosome 1q21 (D1S498, maximum LOD score 6.89 at recombination fraction .00), with no evidence of heterogeneity. Haplotype and multipoint analysis support the location of the PLD locus within a 21.2-cM chromosomal region that is flanked by the markers D1S2881 and D1S484. These data represent an important step in the effort to isolate and characterize the PLD gene. The identification of the gene will have important implications for the understanding of both developmental and metabolic aspects of the adipocyte and may prove useful as a single-gene model for the common metabolic disorder known as "syndrome X."

Cellular sodium membrane transport and cardiovascular risk factors in non-insulin-dependent diabetes mellitus

Association have been described between cardiovascular risk factors and abnormalities of both sodium-lithium countertransport (SLC) and sodium-hydrogen ion exchange in subjects with insulin-dependent diabetes mellitus. The data in subjects with non-insulin-dependent diabetes mellitus (NIDDM) are few and more conflicting. This investigation examines erythrocyte SLC rates and platelet sodium-hydrogen ion-exchange kinetics and their relationship to cardiovascular risk factors in 45 nondiabetic and 35 NIDDM white men. The two groups did not differ significantly in erythrocyte SLC or platelet buffering capacity, sodium-hydrogen ion-exchange maximal rate (Vmax), or Km for extracellular sodium. Within the whole group, controlling for the presence of diabetes, SLC correlated weakly with triglyceride concentration (r = .23, P = .05), but not with urinary albumin excretion rate (AER), systolic or diastolic blood pressure, body mass index (BMI), or concentrations of glucose, insulin, or total or high-density lipoprotein (HDL) cholesterol. Platelet sodium-hydrogen exchange was not significantly related to any cardiovascular risk factor studied. In conclusion, (1)SLC activity was not increased in NIDDM subjects; (2) SLC rates correlated weakly with serum triglyceride concentrations; (3) platelet sodium-hydrogen exchange Vmax and K(m) for extracellular sodium and platelet buffering capacity did not differ between diabetic and nondiabetic groups; and (4) there was no significant relationship between platelet Na+/H(+)-exchange kinetics and any of the cardiovascular risk factors studied.

Association between left ventricular hypertrophy and erythrocyte sodium-lithium exchange in normotensive subjects with and without NIDDM

The determinants of left ventricular mass in normal control subjects and subjects with non-insulin-dependent diabetes (NIDDM) are ill-defined. We therefore recorded M-mode and pulsed Doppler echocardiograms and 24-h ambulatory blood pressure in 57 normotensive subjects, 34 with NIDDM and 23 matched non-diabetic control subjects. Measurements of erythrocyte sodium-lithium counter-transport, plasma angiotensin II, plasma and platelet catecholamines and fasting plasma insulin were also made. Six control subjects (26%) and 15 diabetic subjects (44%) had some degree of left ventricular hypertrophy. Subjects with left ventricular hypertrophy (n = 21) had an elevated mean rate of sodium-lithium countertransport (0.40 +/- 0.13 vs 0.31 +/- 0.09 mmol.l-1.h-1; p < 0.01), parallel differences being observed in both the diabetic and control groups. Twelve of the subjects with left ventricular hypertrophy (57%) had elevated rates of sodium-lithium counter-transport compared to only seven (19%) of those without (p < 0.05). There was no consistent difference between those with and without left ventricular hypertrophy in any other clinical or biochemical variable. Multivariate analysis, with the presence or absence of left ventricular hypertrophy as the dependent variable, demonstrated that the maximal rate of sodium-lithium countertransport was the only variable that independently contributed to left ventricular hypertrophy (partial r = 0.35; F1.55 = 7.74; p = 0.007). This study demonstrates for the first time an association between left ventricular hypertrophy and erythrocyte membrane cation transport that is independent of hypertension, is present in both diabetic and non-diabetic groups, and may represent a link between elevated rates of membrane sodium transport and cardiovascular risk.

Coronary thrombolysis: still too little too late?

We reviewed the case records of 109 consecutive patients with a definite diagnosis of myocardial infarction, admitted through the accident and emergency department of an inner-city general hospital to identify delays in referral to hospital, admission to the coronary care unit, and start of thrombolysis. Of the 109 patients, only 28 (26%) received streptokinase (the only thrombolytic drug used at this hospital), and at least 47 (58%) of the remaining 81 who should have benefited from it did not. However, the proportion of patients given streptokinase improved significantly after publication of the Second International Study of Infarct Survival (ISIS 2) study results. The average delay from onset of symptoms to presentation at the accident department was over 3 hours, with a further 1 hour in-hospital delay before administration of streptokinase. This study revealed considerable underuse of thrombolytic therapy in cases where treatment was clearly indicated, but this picture improved substantially during the period of audit.

Gene probe analysis demonstrates independent clonal evolution of co-existent chronic myeloid and chronic lymphocytic leukaemia

We describe a case of Philadelphia-positive chronic myeloid leukaemia occurring simultaneously with B-cell chronic lymphocytic leukaemia in a 69-yr-old male. Gene probe analysis of DNA from both peripheral blood and bone marrow provided evidence for the independent evolution of 2 clones in this case, with a predominant population showing immunoglobulin heavy chain gene rearrangement and a smaller population showing a rearrangement within the breakpoint cluster region of chromosome 22.