Corinne Collet

Abnormal melatonin synthesis in autism spectrum disorders

Melatonin is produced in the dark by the pineal gland and is a key regulator of circadian and seasonal rhythms. A low melatonin level has been reported in individuals with autism spectrum disorders (ASD), but the underlying cause of this deficit was unknown. The ASMT gene, encoding the last enzyme of melatonin synthesis, is located on the pseudo-autosomal region 1 of the sex chromosomes, deleted in several individuals with ASD. In this study, we sequenced all ASMT exons and promoters in individuals with ASD (n=250) and compared the allelic frequencies with controls (n=255). Non-conservative variations of ASMT were identified, including a splicing mutation present in two families with ASD, but not in controls. Two polymorphisms located in the promoter (rs4446909 and rs5989681) were more frequent in ASD compared to controls (P=0.0006) and were associated with a dramatic decrease in ASMT transcripts in blood cell lines (P=2 × 10−10). Biochemical analyses performed on blood platelets and/or cultured cells revealed a highly significant decrease in ASMT activity (P=2 × 10−12) and melatonin level (P=3 × 10−11) in individuals with ASD. These results indicate that a low melatonin level, caused by a primary deficit in ASMT activity, is a risk factor for ASD. They also support ASMT as a susceptibility gene for ASD and highlight the crucial role of melatonin in human cognition and behavior.

Incremental value of biomarkers to clinical variables for mortality prediction in acutely decompensated heart failure: the Multinational Observational Cohort on Acute Heart Failure (MOCA) study.

AIM This study aims to evaluate the incremental value of plasma biomarkers to traditional clinical variables for risk stratification of 30-day and one-year mortality in acutely decompensated heart failure (ADHF). METHODS AND RESULTS Through an international collaborative network, individual patient data on 5306 patients hospitalized for ADHF were collected. The all-cause mortality rate was 11.7% at 30 days and 32.9% at one year. The clinical prediction model (age, gender, blood pressure on admission, estimated glomerular filtration rate <60 mL/min/1.73 m(2), sodium and hemoglobin levels, and heart rate) had a c-statistic of 0.74 for 30-day mortality and 0.73 for one-year mortality. Several biomarkers measured at presentation improved risk stratification when added to the clinical model. At 30 days, the net reclassification improvement (NRI) was 28.7% for mid-regional adrenomedullin (MR-proADM; p<0.001) and 25.5% for soluble (s)ST2 (p<0.001). At one year, sST2 (NRI 10.3%), MR-proADM (NRI 9.1%), amino-terminal pro-B-type natriuretic peptide (NT-proBNP; NRI 9.1%), mid-regional proatrial natriuretic peptide (MR-proANP; NRI 7.4%), B-type natriuretic peptide (NRI 5.5%) and C-reactive protein (CRP; NRI 5.3%) reclassified patients with ADHF (p<0.05 for all). CRP also markedly improved risk stratification of patients with ADHF as a dual biomarker combination with MR-proADM (NRI 36.8% [p<0.001] for death at 30 days) or with sST2 (NRI 20.3%; [p<0.001] for one-year mortality). CONCLUSION In this study, biomarkers provided incremental value for risk stratification of ADHF patients. Biomarkers such as sST2, MR-proADM, natriuretic peptides and CRP, reflecting different pathophysiologic pathways, add prognostic value to clinical risk factors for predicting both short-term and one-year mortality in ADHF.

Association Between Elevated Blood Glucose and Outcome in Acute Heart Failure Results From an International Observational Cohort

OBJECTIVE The aim of this analysis was to assess the association between elevated blood glucose level and mortality in acute heart failure (AHF). BACKGROUND Elevated blood glucose has been reported to be prognostically meaningful in patients with cardiac diagnoses, such as coronary artery disease. The short-term prognostic impact of hyperglycemia in AHF is unknown, however. METHODS In a multinational cohort of AHF, we examined the ability of blood glucose concentrations at presentation to predict all-cause mortality by 30 days. Fully adjusted models for prognosis included a previous diagnosis of diabetes mellitus as a covariate. RESULTS A total of 6,212 subjects with AHF (mean age, 72 years; 52.5% male) were studied; the median blood glucose concentration on arrival at the hospital was 7.5 mmol/l (135 mg/dl), and 41% had a previous diagnosis of diabetes mellitus (DM). After 30 days, 618 patients (10%) had died. Compared with survivors, decedents had significantly higher median blood glucose concentrations (8.9 mmol/l vs. 7.4 mmol/l; p < 0.0001). In the fully adjusted model, an elevated blood glucose level was an independent predictor of 30-day mortality in AHF (odds ratio: 2.19; 95% confidence interval: 1.69 to 2.83; p < 0.001). The risk associated with an elevated blood glucose level appeared consistent across all subgroups of patients, including patients with preserved (hazard ratio: 5.41; 95% confidence interval: 2.44 to 12.0; p < 0.0001) and impaired systolic function (hazard ratio: 2.37; 95% confidence interval: 1.57 to 3.59; p < 0.0001). Furthermore, in reclassification analyses, elevated blood glucose added significant prognostic information to clinical parameters alone (4.4% net reclassification improvement; p = 0.01). CONCLUSIONS Among patients with AHF, blood glucose concentrations at presentation are powerfully prognostic for 30-day mortality, independent of a diagnosis of diabetes mellitus or other clinical variables. Because blood glucose is easily modifiable, it may represent a valid target for therapeutic intervention.

Paget's Disease of Bone in the French Population: Novel SQSTM1 Mutations, Functional Analysis, and Genotype–Phenotype Correlations

Mutation screening of the SQSTM1 gene in 94 French patients with PDB revealed two novel point‐mutations (A381V and L413F) and two new compound heterozygous genotypes (P392L/A381V and P392L/A390X). Functional analysis showed an increased level of SQSTM1/p62 protein in PDB patients and truncated forms of the protein encoded by the A390X allele. Clinical data indicate that PDB patients with SQSTM1 mutation are younger at PDB diagnosis and have more extensive bone lesions.

Decreased osteoclastogenesis in serotonin-deficient mice

Peripheral serotonin, synthesized by tryptophan hydroxylase-1 (TPH1), has been shown to play a key role in several physiological functions. Recently, controversy has emerged about whether peripheral serotonin has any effect on bone density and remodeling.We therefore decided to investigate in detail bone remodeling in growing and mature TPH1 knockout mice (TPH1−/−). Bone resorption in TPH1−/− mice, as assessed by biochemical markers and bone histomorphometry, was markedly decreased at both ages. Using bone marrow transplantation, we present evidence that the decrease in bone resorption in TPH1−/− mice is cell-autonomous. Cultures from TPH1−/− in the presence of macrophage colony-stimulating factor and receptor activator for NF-KB ligand (RANKL) displayed fewer osteoclasts, and the decreased differentiation could be rescued by adding serotonin. Our data also provide evidence that in the presence of RANKL, osteoclast precursors express TPH1 and synthesize serotonin. Furthermore, pharmacological inhibition of serotonin receptor 1B with SB224289, and of receptor 2A with ketanserin, also reduced the number of osteoclasts. Our findings reveal that serotonin has an important local action in bone, as it can amplify the effect of RANKL on osteoclastogenesis.

Unbiased plasma proteomics for novel diagnostic biomarkers in cardiovascular disease: identification of quiescin Q6 as a candidate biomarker of acutely decompensated heart failure

AIMS Biochemical marker testing has improved the evaluation and management of patients with cardiovascular diseases over the past decade. Natriuretic peptides (NPs), used in clinical practice to assess cardiac dysfunction, exhibit many limitations, however. We used an unbiased proteomics approach for the discovery of novel diagnostic plasma biomarkers of heart failure (HF). METHODS AND RESULTS A proteomics pipeline adapted for very low-abundant plasma proteins was applied to clinical samples from patients admitted with acute decompensated HF (ADHF). Quiescin Q6 (QSOX1), a protein involved in the formation of disulfide bridges, emerged as the best performing marker for ADHF (with an area under the receiver operator characteristic curve of 0.86, 95% confidence interval: 0.79-0.92), and novel isoforms of NPs were also identified. Diagnostic performance of QSOX1 for ADHF was confirmed in 267 prospectively collected subjects of whom 76 had ADHF. Combining QSOX1 to B-type NP (BNP) significantly improved diagnostic accuracy for ADHF by particularly improving specificity. Using thoracic aortic constriction in rats, QSOX1 was specifically induced within both left atria and ventricles at the time of HF onset. CONCLUSION The novel biomarker QSOX1 accurately identifies ADHF, particularly when combined with BNP. Through both clinical and experimental studies we provide lines of evidence for a link between ADHF and cardiovascular production of QSOX1.

Intentional overdose with insulin: prognostic factors and toxicokinetic/toxicodynamic profiles

IntroductionPrognostic factors in intentional insulin self-poisoning and the significance of plasma insulin levels are unclear. We therefore conducted this study to investigate prognostic factors in insulin poisoning, in relation to the value of plasma insulin concentration.MethodsWe conducted a prospective study, and used logistic regression to explore prognostic factors and modelling to investigate toxicokinetic/toxicodynamic relationships.ResultsTwenty-five patients (14 female and 11 male; median [25th to 75th percentiles] age 46 [36 to 58] years) were included. On presentation, the Glasgow Coma Scale score was 9 (4 to 14) and the capillary glucose concentration was 1.4 (1.1 to 2.3) mmol/l. The plasma insulin concentration was 197 (161 to 1,566) mIU/l and the cumulative amount of glucose infused was 301 (184 to 1,056) g. Four patients developed sequelae resulting in two deaths. Delay to therapy in excess of 6 hours (odds ratio 60.0, 95% confidence interval 2.9 to 1,236.7) and ventilation for longer than 48 hours (odds ratio 28.5, 95% confidence interval 1.9 to 420.6) were identified as independent prognostic factors. Toxicokinetic/toxicodynamic relationships between glucose infusion rates and insulin concentrations fit the maximum measured glucose infusion rate (Emax) model (Emax 29.5 [17.5 to 41.1] g/hour, concentration associated with the half-maximum glucose infusion rate [EC50] 46 [35 to 161] mIU/l, and R2 range 0.70 to 0.98; n = 6).ConclusionIntentional insulin overdose is rare. Assessment of prognosis relies on clinical findings. The observed plasma insulin EC50 is 46 mIU/l.

Ineffective erythropoiesis with reduced red blood cell survival in serotonin-deficient mice

Serotonin (5-HT) has long been recognized as a neurotransmitter in the central nervous system, where it modulates a variety of behavioral functions. Availability of 5-HT depends on the expression of the enzyme tryptophan hydroxylase (TPH), and the recent discovery of a dual system for 5-HT synthesis in the brain (TPH2) and periphery (TPH1) has renewed interest in studying the potential functions played by 5-HT in nonnervous tissues. Moreover, characterization of the TPH1 knockout mouse model (TPH1−/−) led to the identification of unsuspected roles for peripheral 5-HT, revealing the importance of this monoamine in regulating key physiological functions outside the brain. Here, we present in vivo data showing that mice deficient in peripheral 5-HT display morphological and cellular features of ineffective erythropoiesis. The central event occurs in the bone marrow where the absence of 5-HT hampers progression of erythroid precursors expressing 5-HT2A and 5-HT2B receptors toward terminal differentiation. In addition, red blood cells from 5-HT–deficient mice are more sensitive to macrophage phagocytosis and have a shortened in vivo half-life. The combination of these two defects causes TPH1−/− animals to develop a phenotype of macrocytic anemia. Direct evidence for a 5-HT effect on erythroid precursors is provided by supplementation of the culture medium with 5-HT that increases the proliferative capacity of both 5-HT–deficient and normal cells. Our thorough analysis of TPH1−/− mice provides a unique model of morphological and functional aberrations of erythropoiesis and identifies 5-HT as a key factor for red blood cell production and survival.

Deconstructing Antiobesity Compound Action: Requirement of Serotonin 5-HT2B Receptors for Dexfenfluramine Anorectic Effects

The now-banned anorectic molecule, dexfenfluramine, promotes serotonin release through a serotonin transporter-dependent mechanism, and it has been widely prescribed for the treatment of obesity. Previous studies have identified that 5-HT2B receptors have important roles in dexfenfluramine side effects, that is, pulmonary hypertension, plasma serotonin level regulation, and valvulopathy. We thus investigated a putative contribution of 5-HT2B receptors in dexfenfluramine-dependent feeding behavior in mice. Interestingly, the hypophagic response to dexfenfluramine (3–10 mg/kg) observed in wild-type mice (1–4 h) was eliminated in mice lacking 5-HT2B receptors (5-HT2B−/−). These findings were further validated by the lack of hypophagic response to dexfenfluramine in wild-type mice treated with RS127445, a highly selective and potent antagonist (pKi=8.22±0.24). Using microdialysis, we observed that in 5-HT2B−/− awake mice, the dexfenfluramine-induced hypothalamic peak of serotonin release (1 h) was strongly reduced (fourfold) compared with wild type. Moreover, using hypothalamic synaptosomes, we established the serotonergic neuron autonomous properties of this effect: a strong serotonin release was observed upon dexfenfluramine stimulation of synaptosome preparation from wild type but not from mice lacking active 5-HT2B receptors. These findings strongly suggest that activation of presynaptic 5-HT2B receptors is a limiting step in the serotonin transporter dependant-releasing effect of dexfenfluramine, whereas other serotonin receptors act downstream with respect to feeding behavior.

Analytical evaluation of the automated galectin-3 assay on the Abbott ARCHITECT immunoassay instruments.

Abstract Background: Galectin-3 is secreted from macrophages and binds and activates fibroblasts forming collagen. Tissue fibrosis is central to the progression of chronic heart failure (CHF). We performed a European multicentered evaluation of the analytical performance of the two-step routine and Short Turn-Around-Time (STAT) galectin-3 immunoassay on the ARCHITECT i1000SR, i2000SR, and i4000SR (Abbott Laboratories). Methods: We evaluated the assay precision and dilution linearity for both routine and STAT assays and compared serum and plasma, and fresh vs. frozen samples. The reference interval and biological variability were also assessed. Measurable samples were compared between ARCHITECT instruments and between the routine and STAT assays and also to a galectin-3 ELISA (BG Medicine). Results: The total assay coefficient of variation (CV%) was 2.3%–6.2% and 1.7%–7.4% for the routine and STAT assays, respectively. Both assays demonstrated linearity up to 120 ng/mL. Galectin-3 concentrations were higher in plasma samples than in serum samples and correlated well between fresh and frozen samples (R=0.997), between the routine and STAT assays, between the ARCHITECT i1000 and i2000 instruments and with the galectin-3 ELISA. The reference interval on 627 apparently healthy individuals (53% male) yielded upper 95th and 97.5th percentiles of 25.2 and 28.4 ng/mL, respectively. Values were significantly lower in subjects younger than 50 years. Conclusions: The galectin-3 routine and STAT assays on the Abbott ARCHITECT instruments demonstrated good analytical performance. Further clinical studies are required to demonstrate the diagnostic and prognostic potential of this novel marker in patients with CHF.