Dosaggio della 3-iodotironamina (T1AM) e sua distribuzione nei tessuti e nel sangue

Lo scopo di questa tesi è la messa a punto di una metodica per il dosaggio quantitativo delle tironamine, ed in particolare della 3-iodotironammima (T1AM), mediante spettrometria di massa accoppiata ad HPLC. È stata svolta una analisi dettagliata dei vari stadi della preparazione del campione e della tecnica di rilevazione per definire le condizioni migliori. Dopo alcuni studi preliminari per individuare il limite di rilevabilità (limit of detection, LOD), il limite di quantificazione (limit of quantification, LOQ), la linearità, l’accuratezza e la specificità, il recupero dell’analita dal processo di estrazione in fase solida, l’effetto matrice (la soppressione ionica) e la stabilità del campione, sono state svolte analisi su campioni ematici umani e su tessuti animali ed umani. Il metodo si è dimostrato in grado di rilevare la presenza di T1AM in tutti i campioni analizzati. È stato quindi possibile confrontare per la prima volta le concentrazioni di T1AM in diversi tessuti di ratto, mostrando che i livelli maggiori si riscontrano nel fegato, nel rene e nel sistema nervoso centrale. Le concentrazioni tissutali risultano essere maggiori delle concentrazioni ematiche, suggerendo l’esistenza di specifici meccanismi di accumulo cellulare, confermati da esperimenti condotti in colture cellulari e nel cuore isolato. A livello tissutale la T1AM va incontro a deaminazione ossidativa a dare acido 3-iodotiroacetico e può essere inoltre deiodinato a dare tironamina. La via di sintesi della T1AM non è stata ancora chiarita, ma esperimenti condotti in vivo dimostrano che la produzione è inibita dal trattamento con perclorato e metimazolo, e che in presenza di tali inibitori della funzione tiroidea la T1AM non può essere prodotta da T4 esogeno. Grazie alla disponibilità di campioni di siero ottenuti da volontari sani, pazienti cardiopatici e pazienti endocrinologici abbiamo potuto dimostrare per la prima volta la presenza di T1AM nel sangue umano, in una casistica di 42 pazienti. La concentrazione media è risultata pari a 0.219±0.012 pmol/mL ed è significativamente correlata a quella degli ormoni tiroidei. Si è inoltre osservata una significativa correlazione con i livelli di emoglobina glicosilata ed un incremento significativo dei suoi livelli in un sottogruppo di pazienti diabetici. La metodica sviluppata è stata inoltre utilizzata per supportare studi comportamentali conseguenti alla somministrazione di T1AM esogeno a topi per via i.c.v.. Si è dimostrato che un aumento dei livelli cerebrali di T1AM di circa un ordine di grandezza si associa ad una migliore performance in test di apprendimento, ad una riduzione della soglia del dolore e a una riduzione dell’assunzione di cibo

Pharmacological effects of 3-iodothyronamine (T1AM) in mice include facilitation of memory acquisition and retention and reduction of pain threshold

BACKGROUND AND PURPOSE: 3-Iodothyronamine (T1AM), an endogenous derivative of thyroid hormones, is regarded as a rapid modulator of behaviour and metabolism. To determine whether brain thyroid hormone levels contribute to these effects, we investigated the effect of central administration of T1AM on learning and pain threshold of mice either untreated or pretreated with clorgyline (2.5 mg•kg-1, i.p.), an inhibitor of amine oxidative metabolism. EXPERIMENTAL APPROACH: T1AM (0.13, 0.4, 1.32 and 4 mg•kg-1) or vehicle was injected i.c.v. into male mice, and after 30 min their effects on memory acquisition capacity, pain threshold and curiosity were evaluated by the following tests: passive avoidance, licking latency on the hot plate and movements on the hole-board platform. Plasma glycaemia was measured using a glucorefractometer. Brain levels of triiodothyroxine (T3), thyroxine (T4) and T1AM were measured by HPLC coupled to tandem MS. ERK1/2 activation and c-fos expression in different brain regions were evaluated by Western blot analysis. RESULTS: T1AM improved learning capacity, decreased pain threshold to hot stimuli, enhanced curiosity and raised plasma glycaemia in a dose-dependent way, without modifying T3 and T4 brain concentrations. T1AM effects on learning and pain were abolished or significantly affected by clorgyline, suggesting a role for some metabolite(s), or that T1AM interacts at the rapid desensitizing target(s). T1AM activated ERK in different brain areas at lower doses than those effective on behaviour. CONCLUSIONS AND IMPLICATIONS: T1AM is a novel memory enhancer. This feature might have important implications for the treatment of endocrine and neurodegenerative-induced memory disorders

STrengthening the REporting of Genetic Association Studies (STREGA)— An Extension of the STROBE Statement

Julian Little and colleagues present the STREGA recommendations, which are aimed at improving the reporting of genetic association studies

Impact of Complete Revascularization on Development of Heart Failure in Patients With Acute Coronary Syndrome and Multivessel Disease: A Subanalysis of the CORALYS Registry

Background The impact of complete revascularization (CR) on the development of heart failure (HF) in patients with acute coronary syndrome and multivessel coronary artery disease undergoing percutaneous coronary intervention remains to be elucidated. Methods and Results Consecutive patients with acute coronary syndrome with multivessel coronary artery disease from the CORALYS (Incidence and Predictors of Heart Failure After Acute Coronary Syndrome) registry were included. Incidence of first hospitalization for HF or cardiovascular death was the primary end point. Patients were stratified according to completeness of coronary revascularization. Of 14 699 patients in the CORALYS registry, 5054 presented with multivessel disease. One thousand four hundred seventy‐three (29.2%) underwent CR, while 3581 (70.8%) did not. Over 5 years follow‐up, CR was associated with a reduced incidence of the primary end point (adjusted hazard ratio [HR], 0.66 [95% CI, 0.51–0.85]), first HF hospitalization (adjusted HR, 0.67 [95% CI, 0.49–0.90]) along with all‐cause death and cardiovascular death alone (adjusted HR, 0.74 [95% CI, 0.56–0.97] and HR, 0.56 [95% CI, 0.38–0.84], respectively). The results were consistent in the propensity‐score matching population and in inverse probability treatment weighting analysis. The benefit of CR was consistent across acute coronary syndrome presentations (HR, 0.59 [95% CI, 0.39–0.89] for ST‐segment elevation myocardial infarction and HR, 0.71 [95% CI, 0.50–0.99] for non‐ST‐elevation acute coronary syndrome) and in patients with left ventricular ejection fraction >40% (HR, 0.52 [95% CI, 0.37–0.72]), while no benefit was observed in patients with left ventricular ejection fraction ≤40% (HR, 0.77 [95% CI, 0.37–1.10], P for interaction 0.04). Conclusions CR after acute coronary syndrome reduced the risk of first hospitalization for HF and cardiovascular death, as well as first HF hospitalization, and cardiovascular and overall death both in patients with ST‐segment elevation myocardial infarction and non‐ST‐elevation acute coronary syndrome. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT 04895176

Duffy antigen receptor for chemokines (Darc) polymorphism regulates circulating concentrations of monocyte chemoattractant protein-1 and other inflammatory mediators

To identify the genetic basis of circulating concentrations of monocyte chemoattractant protein-1 (MCP-1), we conducted genome-wide association analyses for MCP-1 in 3 independent cohorts (n = 9598). The strongest association was for serum MCP-1 with a nonsynonymous polymorphism, rs12075 (Asp42Gly) in DARC, the gene for Duffy antigen receptor for chemokines, a known vascular reservoir of proinflammatory cytokines (minor allele frequency, 45.6%; P < 1.0 * 10−323). This association was supported by family-based genetic linkage at a locus encompassing the DARC gene (genome-wide P = 8.0 * 10−13). Asp42Gly accounted for approximately 20% of the variability in serum MCP-1 concentrations and also was associated with serum concentrations of interleukin-8 and RANTES. While exploring a lack of association between this polymorphism and EDTA plasma MCP-1 concentrations (P = .82), we determined that both clotting and exogenous heparan sulfate (unfractionated heparin) released substantial amounts of MCP-1 from Darc. Quantitative immunoflow cytometry failed to identify meaningful Asp42Gly-associated differences in Darc expression, suggesting that a functional change is responsible for the differential cytokine binding. We conclude that Asp42Gly is a major regulator of erythrocyte Darc-mediated cytokine binding and thereby the circulating concentrations of several proinflammatory cytokines. We have also identified for the first time 2 mechanisms for the release of reservoir chemokines with possible clinical implications

Genome-wide meta-analysis of common variant differences between men and women

The male-to-female sex ratio at birth is constant across world populations with an average of 1.06 (106 male to 100 female live births) for populations of European descent. The sex ratio is considered to be affected by numerous biological and environmental factors and to have a heritable component. The aim of this study was to investigate the presence of common allele modest effects at autosomal and chromosome X variants that could explain the observed sex ratio at birth. We conducted a large-scale genome-wide association scan (GWAS) meta-analysis across 51 studies, comprising overall 114 863 individuals (61 094 women and 53 769 men) of European ancestry and 2 623 828 common (minor allele frequency 0.05) single-nucleotide polymorphisms (SNPs). Allele frequencies were compared between men and women for directly-typed and imputed variants within each study. Forward-time simulations for unlinked, neutral, autosomal, common loci were performed under the demographic model for European populations with a fixed sex ratio and a random mating scheme to assess the probability of detecting significant allele frequency differences. We do not detect any genome-wide significant (P 5 10(8)) common SNP differences between men and women in this well-powered meta-analysis. The simulated data provided results entirely consistent with these findings. This large-scale investigation across approximate to 115 000 individuals shows no detectable contribution from common genetic variants to the observed skew in the sex ratio. The absence of sex-specific differences is useful in guiding genetic association study design, for example when using mixed controls for sex-biased traits

Large-scale association analysis identifies 13 new susceptibility loci for coronary artery disease

We performed a meta-analysis of 14 genome-wide association studies of coronary artery disease (CAD) comprising 22,233 individuals with CAD (cases) and 64,762 controls of European descent followed by genotyping of top association signals in 56,682 additional individuals. This analysis identified 13 loci newly associated with CAD at P < 5 x 10(-8) and confirmed the association of 10 of 12 previously reported CAD loci. The 13 new loci showed risk allele frequencies ranging from 0.13 to 0.91 and were associated with a 6% to 17% increase in the risk of CAD per allele. Notably, only three of the new loci showed significant association with traditional CAD risk factors and the majority lie in gene regions not previously implicated in the pathogenesis of CAD. Finally, five of the new CAD risk loci appear to have pleiotropic effects, showing strong association with various other human diseases or traits