Plasma total ghrelin and leptin levels in human narcolepsy and matched healthy controls: basal concentrations and response to sodium oxybate.

STUDY OBJECTIVES: Narcolepsy is caused by a selective loss of hypocretin neurons and is associated with obesity. Ghrelin and leptin interact with hypocretin neurons to influence energy homeostasis. Here, we evaluated whether human hypocretin deficiency, or the narcolepsy therapeutic agent sodium oxybate, alter the levels of these hormones. METHODS: Eight male, medication free, hypocretin deficient, narcolepsy with cataplexy patients, and 8 healthy controls matched for age, sex, body mass index (BMI), waisttohip ratio, and body fat percentage were assessed. Blood samples of total ghrelin and leptin were collected over 24 hours at 60 and 20-min intervals, respectively, during 2 study occasions: baseline, and during the last night of 5 consecutive nights of sodium oxybate administration (2 × 3.0 g/night). RESULTS: At baseline, mean 24-h total ghrelin (936 ± 142 vs. 949 ± 175 pg/mL, p = 0.873) and leptin (115 ± 5.0 vs. 79.0 ± 32 mg/L, p = 0.18) levels were not different between hypocretin deficient narcolepsy patients and controls. Furthermore, sodium oxybate did not significantly affect the plasma concentration of either one of these hormones. CONCLUSIONS: The increased BMI of narcolepsy patients is unlikely to be mediated by hypocretin deficiency-mediated alterations in total ghrelin or leptin levels. Thus, the effects of these hormones on hypocretin neurons may be mainly unidirectional. Although sodium oxybate may influence body weight, the underlying mechanism is unlikely to involve changes in total ghrelin or leptin secretion.

Effects of adding exercise to a 16-week very low-calorie diet in obese, insulin-dependent type 2 diabetes mellitus patients.

CONTEXT: Reduction of 50% excess body weight, using a very low-calorie diet (VLCD; 450 kcal/d) improves insulin sensitivity in obese type 2 diabetes mellitus patients. OBJECTIVE: The objective of the study was to evaluate whether adding exercise to the VLCD has additional benefits. DESIGN: This was a randomized intervention study. SETTING: The study was conducted at a clinical research center in an academic medical center. SUBJECTS: Twenty-seven obese [body mass index 37.2 ± 0.9 kg/m(2) (mean ± sem)] insulin-treated type 2 diabetes mellitus patients. INTERVENTION: Patients followed a 16-wk VLCD. Thirteen of them simultaneously participated in an exercise program (E) consisting of 1-h, in-hospital training and four 30-min training sessions on a cycloergometer weekly. OUTCOME MEASURES: Insulin resistance was measured by a hyperinsulinemic euglycemic clamp. Insulin signaling, mitochondrial DNA (mtDNA) content, and intramyocellular lipid content was measured in skeletal muscle biopsies. RESULTS: Baseline characteristics were identical in both groups. Substantial weight loss occurred (-23.7 ± 1.7 kg VLCD-only vs. -27.2 ± 1.9 kg VLCD+E, P = NS within groups). The exercise group lost more fat mass. Insulin-stimulated glucose disposal increased similarly in both study groups [15.0 ± 0.9 to 39.2 ± 4.7 µmol/min(-1) · kg lean body mass (LBM(-1)) VLCD-only vs. 17.0 ± 1.0 to 37.5 ± 3.5 µmol/min(-1) · kg LBM(-1) in VLCD+E], as did phosphorylation of the phosphatidylinositol 3-kinase-protein kinase B/AKT insulin signaling pathway. In contrast, skeletal muscle mtDNA content increased only in the VLCD+E group (1211 ± 185 to 2288 ± 358, arbitrary units, P = 0.016 vs. 1397 ± 240 to 1196 ± 179, P = NS, VLCD-only group). Maximum aerobic capacity also only increased significantly in the VLCD+E group (+6.6 ± 1.7 ml/min(-1) · kg LBM(-1) vs. +0.7 ± 1.5 ml/min(-1) · kg LBM(-1) VLCD-only, P = 0.017). CONCLUSION: Addition of exercise to a 16-wk VLCD induces more fat loss. Exercise augments maximum aerobic capacity and skeletal muscle mtDNA content. These changes are, however, not reflected in a higher insulin-stimulated glucose disposal rate.

Hypocretin (orexin) loss in Alzheimer's disease.

Sleep disturbances in Alzheimer's disease (AD) patients are associated with the severity of dementia and are often the primary reason for institutionalization. These sleep problems partly resemble core symptoms of narcolepsy, a sleep disorder caused by a general loss of the neurotransmitter hypocretin. AD is a neurodegenerative disorder targeting different brain areas and types of neurons. In this study, we assessed whether the neurodegenerative process of AD also affects hypothalamic hypocretin/orexin neurons. The total number of hypocretin-1 immunoreactive neurons was quantified in postmortem hypothalami of AD patients (n = 10) and matched controls (n = 10). In addition, the hypocretin-1 concentration was measured in postmortem ventricular cerebrospinal fluid of 24 AD patients and 25 controls (including the patients and controls in which the hypothalamic cell counts were performed). The number of hypocretin-1 immunoreactive neurons was significantly decreased by 40% in AD patients (median [25th-75th percentiles]); AD 12,935 neurons (9972-19,051); controls 21,002 neurons (16,439-25,765); p = 0.049). Lower cerebrospinal fluid (CSF) hypocretin-1 levels were found in AD patients compared with controls (AD: 275 pg/mL [197-317]; controls: 320 pg/mL [262-363]; p = 0.038). Two AD patients with documented excessive daytime sleepiness showed the lowest CSF hypocretin-1 concentrations (55 pg/mL and 76 pg/mL). We conclude that the hypocretin system is affected in advanced AD. This is reflected in a 40% decreased cell number, and 14% lower CSF hypocretin-1 levels.

Serum triiodothyronine levels and inflammatory cytokine production capacity.

Increasing evidence suggests that pro-inflammatory cytokines are at play in lowering peripheral thyroid hormone levels during critical illness. Conversely, thyroid hormones have been suggested to enhance production of inflammatory cytokines. In view of these considerations, we hypothesized a mutual association between triiodothyronine and pro-inflammatory cytokines. Therefore we evaluated the relation between both circulating and induced inflammatory markers and serum thyroid function parameters in the Leiden 85-plus Study. We found that higher circulating levels of inflammatory markers were associated with lower levels of free serum triiodothyronine. In turn, higher serum free triiodothyronine levels were related to higher production capacity of pro-inflammatory cytokines after stimulation with lipopolysaccharide. By combining in vivo and ex vivo data, we were able to demonstrate for the first time the existence of a potential feedback mechanism between thyroid function and immune production capacity. We conclude that maintenance of normal thyroid function might be important for a preserved immune response in elderly human populations.

Abdominal fat accumulation in adults born preterm exposed antenatally to maternal glucocorticoid treatment is dependent on glucocorticoid receptor gene variation.

CONTEXT: Preterm birth is associated with short stature, abdominal adiposity, insulin resistance, and hypertension, resembling effects of increased glucocorticoid bioactivity. Although antenatal glucocorticoid treatment does not substantially contribute to these associations, it is unknown whether genetic variants in the glucocorticoid receptor gene could modulate the effects of antenatal glucocorticoid treatment on the above phenotype. OBJECTIVE: Our objective was to test the effects of the R23K and N363S variants, associated with decreased and increased sensitivity to cortisol, respectively, on the metabolic profile in adults born preterm of whom some had been treated with glucocorticoids antenatally and/or in the early postnatal phase. DESIGN AND PARTICIPANTS: This was a prospective follow-up study that included 263 19-year-olds born at a gestational age under 32 wk from the Dutch Project on Preterm and Small-for-Gestational-Age Infants cohort. SETTING: This was a nationwide multicenter follow-up study. MAIN OUTCOME MEASURES: Adult height and body composition, fasting serum glucose, insulin and cholesterol levels, and blood pressure were evaluated. RESULTS: At 19 yr of age, waist circumference was 1.67 ± 0.90 sd score in 363S carriers who had been treated antenatally with glucocorticoids (n = 4), which was much higher than that of the other groups (P for interaction = 0.03). A similar association was found for the waist-to-hip ratio sd score (P = 0.03). Similar associations were absent with the R23K polymorphism. There was no interaction between these genotypes and postnatal glucocorticoid treatment on serum levels of glucose, insulin, and cholesterol or blood pressure. CONCLUSIONS: In prematurely born individuals carrying the 363S variant, antenatal glucocorticoid treatment predisposes to abdominal adiposity at age 19 yr.

Effect of sodium oxybate on growth hormone secretion in narcolepsy patients and healthy controls.

Hypocretin deficiency causes narcolepsy and may affect neuroendocrine systems and body composition. Additionally, growth hormone (GH) alterations my influence weight in narcolepsy. Symptoms can be treated effectively with sodium oxybate (SXB; γ-hydroxybutyrate) in many patients. This study compared growth hormone secretion in patients and matched controls and established the effect of SXB administration on GH and sleep in both groups. Eight male hypocretin-deficient patients with narcolepsy and cataplexy and eight controls matched for sex, age, BMI, waist-to-hip ratio, and fat percentage were enrolled. Blood was sampled before and on the 5th day of SXB administration. SXB was taken two times 3 g/night for 5 consecutive nights. Both groups underwent 24-h blood sampling at 10-min intervals for measurement of GH concentrations. The GH concentration time series were analyzed with AutoDecon and approximate entropy (ApEn). Basal and pulsatile GH secretion, pulse regularity, and frequency, as well as ApEn values, were similar in patients and controls. Administration of SXB caused a significant increase in total 24-h GH secretion rate in narcolepsy patients, but not in controls. After SXB, slow-wave sleep (SWS) and, importantly, the cross-correlation between GH levels and SWS more than doubled in both groups. In conclusion, SXB leads to a consistent increase in nocturnal GH secretion and strengthens the temporal relation between GH secretion and SWS. These data suggest that SXB may alter somatotropic tone in addition to its consolidating effect on nighttime sleep in narcolepsy. This could explain the suggested nonsleep effects of SXB, including body weight reduction.

Incident venous thromboembolic events in the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER).

BACKGROUND: Venous thromboembolic events (VTE), including deep venous thrombosis and pulmonary embolism, are common in older age. It has been suggested that statins might reduce the risk of VTE however positive results from studies of middle aged subjects may not be generalisable to elderly people. We aimed to determine the effect of pravastatin on incident VTE in older people; we also studied the impact of clinical and plasma risk variables. METHODS: This study was an analysis of incident VTE using data from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER), a randomized, double-blind, placebo-controlled trial of pravastatin in men and women aged 70-82. Mean follow-up was 3.2 years. Risk for VTE was examined in non-warfarin treated pravastatin (n = 2834) and placebo (n = 2865) patients using a Cox's proportional hazard model, and the impact of other risk factors assessed in a multivariate forward stepwise regression analysis. Baseline clinical characteristics, blood biochemistry and hematology variables, plasma levels of lipids and lipoproteins, and plasma markers of inflammation and adiposity were compared. Plasma markers of thrombosis and hemostasis were assessed in a nested case (n = 48) control (n = 93) study where the cohort was those participants, not on warfarin, for whom data were available. RESULTS: There were 28 definite cases (1.0%) of incident VTE in the pravastatin group recipients and 20 cases (0.70%) in placebo recipients. Pravastatin did not reduce VTE in PROSPER compared to placebo [unadjusted hazard ratio (95% confidence interval) 1.42 (0.80, 2.52) p = 0.23]. Higher body mass index (BMI) [1.09 (1.02, 1.15) p = 0.0075], country [Scotland vs Netherlands 4.26 (1.00, 18.21) p = 0.050 and Ireland vs Netherlands 6.16 (1.46, 26.00) p = 0.013], lower systolic blood pressure [1.35 (1.03, 1.75) p = 0.027] and lower baseline Mini Mental State Examination (MMSE) score [1.19 (1.01, 1.41) p = 0.034] were associated with an increased risk of VTE, however only BMI, country and systolic blood pressure remained significant on multivariate analysis. In a nested case control study of definite VTE, plasma Factor VIII levels were associated with VTE [1.52 (1.01, 2.28), p = 0.044]. However no other measure of thrombosis and haemostasis was associated with increased risk of VTE. CONCLUSIONS: Pravastatin does not prevent VTE in elderly people at risk of vascular disease. Blood markers of haemostasis and inflammation are not strongly predictive of VTE in older age however BMI, country and lower systolic blood pressure are independently associated with VTE risk. TRIAL REGISTRATION: Not applicable when study undertaken.

Sodium oxybate increases prolactin secretion in narcolepsy patients and healthy controls.

OBJECTIVE: Hypocretin deficiency causes narcolepsy and may affect neuroendocrine systems, including TSH, ACTH and LH secretion. Symptoms can be treated effectively with sodium oxybate (SXB) in many patients. This study was performed to compare prolactin (PRL) secretion in patients and matched controls and establish the effect of SXB administration on PRL and sleep in both the groups. DESIGN: Open label intervention. Blood was sampled before and after 5 days of SXB treatment. The study was performed at the Leiden University Medical Centre, Leiden, The Netherlands. METHODS: Subjects were admitted to the clinical research centre on both occasions. PATIENTS OR PARTICIPANTS: Eight male hypocretin-deficient narcolepsy with cataplexy patients and eight controls matched for sex, age, body mass index, waist-to-hip ratio and fat percentage were enrolled. INTERVENTIONS: SXB two times 3 g per night for five consecutive nights. RESULTS: Patients and controls underwent 24 h blood sampling at 10 min intervals for measurement of PRL concentrations. The PRL concentration time series was analysed with a new deconvolution programme, approximate entropy (ApEn) and Cosinor analysis. Sleep was polygraphically recorded. Basal and pulsatile PRL secretion, as well as pulse regularity and frequency, ApEn and diurnal parameters were similar in patients and controls. SXB treatment caused similar nocturnal increase in PRL secretion, advance of the acrophase and decrease in ApEn in patients and controls. Slow wave sleep was increased to a similar extent in patients and controls. CONCLUSION: This detailed study did not demonstrate altered PRL secretion in hypocretin-deficient narcolepsy patients during the basal state or during SXB administration. Therefore, hypocretin signalling is unlikely to be a regulator of the lactotrophic system.

Systemic energy homeostasis in Huntington's disease patients.

BACKGROUND: Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an increased number of CAG repeats in the HTT gene. Apart from neurological impairment, the disease is also accompanied by progressive weight loss, abnormalities in fat and glucose homeostasis and a higher prevalence of diabetes mellitus, the causes of which are unknown. Therefore, a detailed analysis of systemic energy homeostasis in HD patients in relation to disease characteristics was performed. METHODS: Indirect calorimetry combined with a hyperinsulinaemic-euglycaemic clamp with stable isotopes ([6,6-2H2]-glucose and [2H5]- glycerol) was performed to assess energy expenditure and glucose and fat metabolism in nine early stage, medication free HD patients and nine age, sex and body mass index matched controls. RESULTS: Compared with controls, fasting energy expenditure was higher in HD patients (1616 ± 72 vs 1883 ± 93 kcal/24 h, p=0.037) and increased even further after insulin stimulation (1667 ± 87 vs 2068 ± 122 kcal/24 h, p=0.016). During both basal and hyperinsulinaemic conditions, glucose and glycerol disposal rates, endogenous glucose production and hepatic insulin sensitivity were similar between HD patients and controls. In HD patients, energy expenditure increased with disease duration but not with a greater degree of motor or functional impairment. Moreover, a higher mutant CAG repeat size was associated with lower insulin sensitivity (r=-0.84, p=0.018). CONCLUSION: These findings suggest sympathetic hyperactivity as an underlying mechanism of increased energy expenditure in HD, as well as peripheral polyglutamine length dependent interference of mutant huntingtin with insulin signalling that may become clinically relevant in carriers of mutations with large CAG repeat sizes.

Altered thyrotropic and lactotropic axes regulation in Huntington's disease.

BACKGROUND: Recently, a loss of hypothalamic dopamine D(2) receptors was demonstrated in Huntington's disease (HD). Activation of dopamine D(2) receptors is known to inhibit the function of both thyrotropic and lactotropic axes. OBJECTIVE: To assess whether the activity of the thyrotropic and lactotropic axes is disturbed in patients with HD, contributing to symptoms such as unintended weight loss. PARTICIPANTS AND METHODS: In nine medication-free patients with early-stage HD (six men, three women) and nine age-, sex- and body mass index-matched controls, we measured serum levels of thyroid-stimulating hormone (TSH) and prolactin (men only) every 10 min for 24 h. Multiparameter auto-deconvolution and approximate entropy analysis were applied to quantify basal, pulsatile and total TSH and prolactin secretion rates as well as the regularity of hormone release. RESULTS: Compared with controls, TSH and prolactin secretion tended to be slightly, but not significantly, higher in patients with HD (TSH: 1.13 ± 0.14 vs 0.91 ± 0.19 mU/l, P = 0.40; prolactin: 213 ± 18 vs 209 ± 11 pmol/l, P = 0.87). However, in patients with HD, total T(3) levels were significantly higher (1.60 ± 0.05 vs 1.35 ± 0.09, P = 0.045), while T(4) levels tended to be higher as well (91.9 ± 3.9 vs 81.3 ± 3.1, P = 0.085). Prolactin secretion was significantly more irregular in patients with HD (Approximate entropy (ApEn): 1.06 ± 0.08 vs 0.80 ± 0.09, P = 0.037). Total T(3) levels were negatively associated with motor impairment (r = -0.72, P = 0.030), whereas increasing free T(4) levels were associated with a larger mutant cytosine-adenine-guanine (CAG) repeat size (r = +0.68, P = 0.044). CONCLUSION: Our findings indicate a mild hyperactivity of the thyrotropic axis and a disturbed regulation of the lactotropic axis in patients with early-stage HD.

Orally disintegrating and oral standard olanzapine tablets similarly elevate the homeostasis model assessment of insulin resistance index and plasma triglyceride levels in 12 healthy men: a randomized crossover study.

OBJECTIVE: Treatment with olanzapine is associated with obesity, diabetes mellitus, and dyslipidemia. Reports have indicated that orally disintegrating tablets (ODT) cause less weight gain than oral standard tablets (OST). The aim of this study was to compare the effect of short-term treatment with these 2 distinct olanzapine formulations on glucose and lipid metabolism in healthy men. METHOD: Twelve healthy men (mean ± SEM age: 25.1 ± 5.5 years) received olanzapine ODT (10 mg od, 8 days), olanzapine OST (10 mg od, 8 days), or no intervention in a randomized crossover design. At breakfast and dinner, glucose, insulin, free fatty acids (FFA), and triglyceride concentrations were measured at 10-minute intervals from 30 minutes prior to 2 hours after ingestion of standard meals. Leptin and adiponectin concentrations were measured at 20- and 30-minute intervals, respectively, between 0000h-1200h. Physical activity was assessed with an accelerometer. Fuel oxidation was measured in fasting condition by indirect calorimetry. The study was conducted from April 2006 through September 2006. RESULTS: Treatment with olanzapine ODT and OST equally elevated the homeostasis model assessment of insulin resistance (HOMA-IR) (P = .005). At breakfast, both formulations equally increased fasting and postprandial triglyceride concentrations (P = .013 and P = .005, respectively) while decreasing fasting and postprandial FFA concentrations (P = .004 and P = .009, respectively). Body weight, body composition, physical activity, or fuel oxidation did not differ between treatment modalities. CONCLUSIONS: Eight days of treatment with both olanzapine formulations similarly increased HOMA-IR and triglyceride concentrations and decreased FFA concentrations in response to standard meals without affecting anthropometrics or physical activity. These data suggest that olanzapine hampers insulin action via mechanistic routes other than body adiposity or physical inactivity. TRIAL REGISTRATION: controlled-trials.com. Identifier: ISRCTN17632637.

Favorable glucose tolerance and lower prevalence of metabolic syndrome in offspring without diabetes mellitus of nonagenarian siblings: the Leiden longevity study.

OBJECTIVES: To explore measures of metabolic syndrome and glucose metabolism in families with exceptional longevity. DESIGN: Case-control study. SETTING: A university hospital in Leiden, the Netherlands. PARTICIPANTS: One hundred twenty-one offspring of nonagenarian siblings, who were enriched for familial factors promoting longevity, and 113 of their partners. No subject had diabetes mellitus. MEASUREMENTS: Prevalence of metabolic syndrome was determined according to the criteria of the Third Report of the National Cholesterol Education Program. Glucose tolerance was assessed according to a 2-hour oral glucose tolerance test. RESULTS: The offspring of nonagenarians siblings had a lower prevalence of metabolic syndrome (P=.03), similar body composition, lower mean fasting blood glucose levels (4.99 vs 5.16 mmol/L; P=.01), lower mean fasting insulin levels (5.81 vs 6.75 mU/L; P=.04), a higher mean homeostasis model assessment of insulin sensitivity (0.78 vs 0.65; P=.02), and a more-favorable glucose tolerance (mean area under the receiver operating characteristic curve for glucose (13.2 vs 14.3; P=.007) than their partners. No significant differences were observed between the offspring and their partners in beta-cell function (insulogenic index 13.6 vs 12.5; P=.38). CONCLUSION: Despite similar body composition, the offspring of nonagenarian siblings showed a lower prevalence of metabolic syndrome and better glucose tolerance than their partners, centralizing the role of favorable glucose metabolism in familial longevity.

Genetic architecture of plasma adiponectin overlaps with the genetics of metabolic syndrome-related traits.

OBJECTIVE: Adiponectin, a hormone secreted by adipose tissue, is of particular interest in metabolic syndrome, because it is inversely correlated with obesity and insulin sensitivity. However, it is not known to what extent the genetics of plasma adiponectin and the genetics of obesity and insulin sensitivity are interrelated. We aimed to evaluate the heritability of plasma adiponectin and its genetic correlation with the metabolic syndrome and metabolic syndrome-related traits and the association between these traits and 10 ADIPOQ single nucleotide polymorphisms (SNPs). RESEARCH DESIGN AND METHODS: We made use of a family-based population, the Erasmus Rucphen Family study (1,258 women and 967 men). Heritability analysis was performed using a polygenic model. Genetic correlations were estimated using bivariate heritability analyses. Genetic association analysis was performed using a mixed model. RESULTS: Plasma adiponectin showed a heritability of 55.1%. Genetic correlations between plasma adiponectin HDL cholesterol and plasma insulin ranged from 15 to 24% but were not significant for fasting glucose, triglycerides, blood pressure, homeostasis model assessment of insulin resistance (HOMA-IR), and C-reactive protein. A significant association with plasma adiponectin was found for ADIPOQ variants rs17300539 and rs182052. A nominally significant association was found with plasma insulin and HOMA-IR and ADIPOQ variant rs17300539 after adjustment for plasma adiponectin. CONCLUSIONS: The significant genetic correlation between plasma adiponectin and HDL cholesterol and plasma insulin should be taken into account in the interpretation of genome-wide association studies. Association of ADIPOQ SNPs with plasma adiponectin was replicated, and we showed association between one ADIPOQ SNP and plasma insulin and HOMA-IR.

Effects of olanzapine and haloperidol on the metabolic status of healthy men.

BACKGROUND: A large body of evidence suggests that antipsychotic drugs cause body weight gain and type 2 diabetes mellitus, and atypical (new generation) drugs appear to be most harmful. The aim of this study was to determine the effect of short-term olanzapine (atypical antipsychotic drug) and haloperidol (conventional antipsychotic drug) treatment on glucose and lipid metabolism. RESEARCH DESIGN AND METHODS: Healthy normal-weight men were treated with olanzapine (10 mg/d; n = 7) or haloperidol (3 mg/d, n = 7) for 8 d. Endogenous glucose production, whole body glucose disposal (by [6,6-(2)H(2)]glucose dilution), lipolysis (by [(2)H(5)]glycerol dilution), and substrate oxidation rates (by indirect calorimetry) were measured before and after intervention in basal and hyperinsulinemic condition. RESULTS: Olanzapine hampered insulin-mediated glucose disposal (by 1.3 mg x kg(-1) x min(-1)), whereas haloperidol did not have a significant effect. Endogenous glucose production was not affected by either drug. Also, the glycerol rate of appearance (a measure of lipolysis rate) was not affected by either drug. Olanzapine, but not haloperidol, blunted the insulin-induced decline of plasma free fatty acid and triglyceride concentrations. Fasting free fatty acid concentrations declined during olanzapine treatment, whereas they did not during treatment with haloperidol. CONCLUSIONS: Short-term treatment with olanzapine reduces fasting plasma free fatty acid concentrations and hampers insulin action on glucose disposal in healthy men, whereas haloperidol has less clear effects. Moreover, olanzapine, but not haloperidol, blunts the insulin-induced decline of plasma free fatty acids and triglyceride concentrations. Notably, these effects come about without a measurable change of body fat mass.

Genetic variation in pentraxin (PTX) 3 gene associates with PTX3 production and fertility in women.

Pentraxin 3 (PTX3) plays an important role in innate immune responses and in female fertility, as discovered with studies in mice. However, the role of PTX3 in human fertility is unknown. Here, we report on a population-based study from a rural area of Upper East Ghana (n = 4346). We studied the association between the number of children given birth by women during their lifetime and ex vivo, lipopolysaccharide (LPS)-induced PTX3 production (n = 362). In addition, we studied the association of genetic variation in the PTX3 gene with PTX3 production (n = 617) and with female fertility (n = 1999). We found that ex vivo LPS-induced PTX3 production was associated with fertility (P = 0.040). Furthermore, we identified genetic variants in the PTX3 gene that influence PTX3 production, and also fertility. The strongest associations were observed for the rs6788044 single-nucleotide polymorphism (SNP). We found that carriers of this SNP had higher PTX3 production capacity (P = 0.003) and higher fertility (P = 0.043). The results reported here provide the first evidence, based on protein production and analysis of polymorphisms, that the long pentraxin PTX3 plays a role in female fertility in humans.

Polymorphisms in TLR4 and TLR2 genes, cytokine production and survival in rural Ghana.

Toll-like receptors (TLRs) are involved in the induction of an adequate immune response on infection. We hypothesized that genetic variation in TLR4 and TLR2 genes could influence this response and lead to variability in cytokine production and survival. We tested this hypothesis in 4292 participants who were followed up for all-cause mortality for 6 years and live under adverse environmental conditions in the Upper-East region of Ghana, where malaria is endemic. In 605 participants, tumor necrosis factor-alpha and interleukin-10 (IL10) production, after stimulation with lipopolysaccharide and zymosan, was measured. In addition, 34 single-nucleotide polymorphisms (SNPs) in TLR4 and 12 SNPs in TLR2 were genotyped and tested for association with cytokine production, malaria infection and mortality. In this comprehensive gene-wide approach, we identified novel SNPs in the TLR4 gene that influence cytokine production. From the analyzed SNPs, rs7860896 associated the strongest with IL10 production (P=0.0005). None of the SNPs in this study associated with malaria or overall mortality risks. In conclusion, we demonstrate that genetic variation within the TLR4 gene influences cytokine production capacity, but in an endemic area does not influence the susceptibility to malaria infection or mortality.

Leptin secretion rate increases with higher CAG repeat number in Huntington's disease patients.

BACKGROUND: Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an increased number of CAG repeats in the huntingtin gene. A hallmark of HD is unintended weight loss, the cause of which is unknown. OBJECTIVE: To perform a detailed analysis of adipose tissue function in HD patients as abnormal fat tissue function could contribute to the weight loss. DESIGN, SETTING AND PARTICIPANTS: In a clinical research laboratory, 24-h plasma concentrations of leptin, adiponectin and resistin were studied in nine early-stage, medication-free HD patients and nine age-, gender- and body mass index (BMI)-matched controls. MEASUREMENTS: Leptin was measured every 20 min whereas adiponectin and resistin were measured hourly. Autodeconvolution and cosinor regression were applied to quantify secretion characteristics of leptin and diurnal variations in leptin, adiponectin and resistin levels. RESULTS: Plasma levels and diurnal rhythmicity of leptin, adiponectin and resistin were not significantly different between HD patients and controls. However, although leptin production increased with higher BMI and fat mass in controls, no such relation was present in HD patients. Moreover, when corrected for fat mass, mean plasma leptin concentration as well as basal, pulsatile and total secretion rates increased with the size of the CAG repeat mutation (r = +0.72 to r = +0.80; all P < 0.05). Both higher pulsatile leptin secretion and higher mean adiponectin levels were associated with a greater degree of motor and functional impairment in HD patients. CONCLUSIONS: CAG-repeat size-dependent interference of the HD mutation with adipose tissue function may contribute to weight loss in HD patients.

Low serum free triiodothyronine levels mark familial longevity: the Leiden Longevity Study.

BACKGROUND: The hypothalamo-pituitary-thyroid axis has been widely implicated in modulating the aging process. Life extension effects associated with low thyroid hormone levels have been reported in multiple animal models. In human populations, an association was observed between low thyroid function and longevity at old age, but the beneficial effects of low thyroid hormone metabolism at middle age remain elusive. METHODS: We have compared serum thyroid hormone function parameters in a group of middle-aged offspring of long-living nonagenarian siblings and a control group of their partners, all participants of the Leiden Longevity Study. RESULTS: When compared with their partners, the group of offspring of nonagenarian siblings showed a trend toward higher serum thyrotropin levels (1.65 vs157 mU/L, p = .11) in conjunction with lower free thyroxine levels (15.0 vs 15.2 pmol/L, p = .045) and lower free triiodothyronine levels (4.08 vs 4.14 pmol/L, p = .024). CONCLUSIONS: Compared with their partners, the group of offspring of nonagenarian siblings show a lower thyroidal sensitivity to thyrotropin. These findings suggest that the favorable role of low thyroid hormone metabolism on health and longevity in model organism is applicable to humans as well.