Neuronal HSF-1 coordinates the propagation of fat desaturation across tissues to enable adaptation to high temperatures in C. elegans.

To survive elevated temperatures, ectotherms adjust the fluidity of membranes by fine-tuning lipid desaturation levels in a process previously described to be cell autonomous. We have discovered that, in Caenorhabditis elegans, neuronal heat shock factor 1 (HSF-1), the conserved master regulator of the heat shock response (HSR), causes extensive fat remodeling in peripheral tissues. These changes include a decrease in fat desaturase and acid lipase expression in the intestine and a global shift in the saturation levels of plasma membrane's phospholipids. The observed remodeling of plasma membrane is in line with ectothermic adaptive responses and gives worms a cumulative advantage to warm temperatures. We have determined that at least 6 TAX-2/TAX-4 cyclic guanosine monophosphate (cGMP) gated channel expressing sensory neurons, and transforming growth factor ß (TGF-ß)/bone morphogenetic protein (BMP) are required for signaling across tissues to modulate fat desaturation. We also find neuronal hsf-1 is not only sufficient but also partially necessary to control the fat remodeling response and for survival at warm temperatures. This is the first study to show that a thermostat-based mechanism can cell nonautonomously coordinate membrane saturation and composition across tissues in a multicellular animal.

Methods for the relative quantitation of human plasma lipidome using liquid chromatography coupled with mass spectrometry using minimal sample manipulation.

Extraction protocols and liquid chromatography coupled with mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS) methods for the measurement of four lipid categories, namely glycerophospholipids, glycerolipids, sphingolipids and sterol lipids in human plasma, are described here. Step-by-step instructions are provided for the liquid-liquid extraction methods, including solution preparation and the non-endogenous lipid internal standards used. All instrumental conditions, chromatography columns and solutions required for the LC-MS and LC-MS/MS methods are also provided in detail.

Comprehensive lipidome of human plasma using minimal sample manipulation by liquid chromatography coupled with mass spectrometry.

RATIONALE: The present work shows comprehensive chromatographic methods and MS conditions that have been developed based on the chemical properties of each lipid subclass to detect low-abundance molecular species. This study shows that the developed methods can detect low- and/or very-low-abundant lipids like phosphatidic acid (PA) in the glycerophospholipid (GP) method; dihydroceramide (dhCer) and dihydrosphingosine/sphinganine (dhSPB) in the sphingolipid (SP) method; and lysophosphatidic acid (LPA), LPI, LPG and sphingosine-1-phosphate (SPBP) in the lysolipid method. METHODS: An optimised method for the extraction of lysolipids in plasma is used in addition to Folch extraction. Then, four chromatographic methods coupled with mass spectrometry using targeted and untargeted approaches are described here. Three of the methods use a tertiary pumping system to enable the inclusion of a gradient for analyte separation (pumps A and B) and an isocratic wash (pump C). This wash solution elutes interfering compounds that could cause background signal in the subsequent injections, reducing column lifetime. RESULTS: Semi-quantitative values for 37 lipid subclasses are reported for a plasma sample (NIST SRM 1950). Furthermore, the methods presented here enabled the identification of 338 different lipid molecular species for GPs (mono- and diacyl-phospholipds), SPs, sterols and glycerolipids. The methods have been validated, and the reproducibility is presented here. CONCLUSIONS: The comprehensive analysis of the lipidome addressed here of glycerolipids, GPs, sterols and SPs is in good agreement with previously reported results, in the NIST SRM 1950 sample, by other laboratories. Ten lipid subclasses LPS, LPI, alkyl-lysophosphatidic acid/alkenyl-lysophosphatidic acid, alkyl-lysophosphatidylethanolamine/alkenyl-lysophosphatidylethanolamine, dhCer (d18:0), SPB (d18:1), dhSPB (d18:0) and SPBP (d18:2) have been detected using this comprehensive method and are uniquely reported here.

A mass spectrometry approach for the identification and localization of small aldehyde modifications of proteins.

Lipids containing polyunsaturated fatty acids are primary targets of oxidation, which produces reactive short-chain aldehydes that can covalently modify proteins, a process called lipoxidation. Improved mass spectrometry (MS) methods for the analysis of these adducts in complex biological systems are needed. Lysozyme and human serum albumin (HSA) were used as model proteins to investigate lipoxidation products formed by two short-chain aldehydes, acrolein and pentanal, which are unsaturated and saturated aldehydes respectively. The adducts formed were stabilized by NaBH4 or NaBH3CN reduction and analysed by MS. Analysis of intact modified lysozyme showed a pentanal modification resulting from Schiff's base formation (+70 Da), and up to 8 acrolein adducts, all resulting from Michael addition (+58 Da). Analysis of tryptic digests identified specific histidine, cysteine and lysine residues modified in both lysozyme and HSA, and determined characteristic amino acid-specific fragmentations. Eight different internal fragment ions were found that could be used as general diagnostic ions for pentanal- and acrolein-modified amino acids. The combined use of intact protein analysis and LC-MS/MS methods provided a powerful tool for the identification and localization of aldehyde-protein adducts, and the diagnostic ions will facilitate the development of targeted MS methods for analysis of adducts in more complex samples.

Alteration in Phospholipidome Profile of Myoblast H9c2 Cell Line in a Model of Myocardium Starvation and Ischemia.

Myocardium infarction is one of the most deathly cardiovascular diseases. It is characterized by myocardium ischemia as a result of nutrients depletion and hypoxia. The cell can respond to this injury by autophagy or apoptosis, which determines the evolution and possible recovery of the myocardium infarction. Lipids play an important role in cardiovascular disease. However reports stating lipidome variations in cardiovascular disease are scarce and the role that lipids play in this pathological condition is not completely understood. The aim of this work was to identify changes in lipid profile of a myoblast H9c2 cell line under starvation and ischemia, to better understand and recognize new biomarkers for myocardial infarction. Lipidomic profile was evaluated by HILIC-LC-MS and GC-MS. Cardiac cells showed alterations in phosphatidylcholines PC (34:1) and PC (36:2), lysophosphatidylcholines lyso PC(16:0), lysoPC(18:1) and lysoPC(18:0), phosphatidylethanolamine PE (34:1), phosphatidylserine PS (36:1), phosphatidylinositol PI (36:2), PI (38:3) and PI (38:5), sphingomyelin SM (34:1) and cardiolipins CL(68:4), CL(72:5) and CL(74:7) in ischemia and/or starvation, in comparison with control. Specific differences observed only in starvation were decrease of SM (34:1) and FA (20:4), and increase of PS (36:1). Differences observed only in ischemia were decrease of PC (36:2), lyso PC (16:0) and FA (18:1) and simultaneous increase of FA (16:0), and FA (18:0). Interestingly, PC (34:1) increased in ischemia and decreased in starvation. In conclusion, our work suggests that lipids are potential markers for evaluation of cell fate, either cell death or recovery, which will be useful to improve diagnosis and prognostic of cardiovascular diseases. J. Cell. Physiol. 231: 2266-2274, 2016. © 2016 Wiley Periodicals, Inc.

Lipidomics of Mesenchymal Stromal Cells: Understanding the Adaptation of Phospholipid Profile in Response to Pro-Inflammatory Cytokines.

Mesenchymal stromal cells (MSCs) present anti-inflammatory properties and are being used with great success as treatment for inflammatory and autoimmune diseases. In clinical applications MSCs are subjected to a strong pro-inflammatory environment, essential to their immunosuppressive action. Despite the wide clinical use of these cells, how MSCs exert their effect remains unclear. Several lipids are known to be involved in cell's signaling and modulation of cellular functions. The aim of this paper is to examine the variation in lipid profile of MSCs under pro-inflammatory environment, induced by the presence of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ), using the most modern lipidomic approach. Major changes in lipid molecular profile of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), lysoPC (LPC), and sphingomyelin (SM) classes were found. No changes were observed in the phosphatidylinositol (PI) profile. The levels of PC species with shorter fatty acids (FAs), mainly C16:0, decreased under pro-inflammatory stimuli. The level of PC(40:6) also decreased, which may be correlated with enhanced levels of LPC(18:0), which is known to be an anti-inflammatory LPC, observed in MSCs subjected to TNF-α and IFN-γ. Simultaneously, the relative amounts of PC(36:1) and PC(38:4) increased. TNF-α and IFN-γ also enhanced the levels of PE(40:6) and decreased the levels of PE(O-38:6). Higher expression of PS(36:1) and SM(34:0) along with a decrease in PS(38:6) levels were observed. These results indicate that lipid metabolism and signaling are modulated during MSCs activation, which suggests that lipids may be involved in MSCs functional and anti-inflammatory activities.

Diagnosis of Congenital Toxoplasmosis: Challenges and Management Outcomes.

Introduction Congenital toxoplasmosis (CT), despite being mostly subclinical at birth, can cause disabling disease in the fetus and lead to long-term sequelae. It is an important cause of chorioretinitis in infants and adolescents. Data on postnatal treatment are controversial, and there is a lack of universal guidelines. Methods A cross-sectional study of newborns with suspected CT was conducted between January 2007 and December 2021. Results Seventy-one patients with suspected CT were included. During pregnancy, 64 (90.1%) of the mothers underwent therapy, of which 59 (83.1%) with spiramycin. Amniocentesis identified one positive polymerase chain reaction assay. Most newborns were asymptomatic with normal laboratory, ophthalmological, and hearing screening. There was one case of hyperproteinorrachia. Fifty-seven patients (80.3%) started treatment: 42 (73.7%) with spiramycin, seven (12.3%) with pyrimethamine, sulfadiazine, and folinic acid (P+S+FA), and eight (14%) with P+S+FA intercalated with spiramycin. Adverse effects were found in 11 (19.3%) cases, mainly neutropenia. After investigation, we found three confirmed CT cases corresponding to 4.2% of suspected cases and an incidence of 0.4 per 10,000 births. All had normal clinical and laboratory exams in the neonatal period and started P+S+FA, fulfilling 12 months of therapy. During the follow-up, all presented normal psychomotor development without any long-term sequelae. Conclusion The lower incidence in our study, compared to the incidence in Europe, may be related to the decline in the prevalence of toxoplasmosis as well as the effectiveness of measures to prevent primary infection and a well-established program of antenatal screening, followed by the early initiation of treatment during pregnancy to prevent vertical transmission.

Concordant inter-laboratory derived concentrations of ceramides in human plasma reference materials via authentic standards.

In this community effort, we compare measurements between 34 laboratories from 19 countries, utilizing mixtures of labelled authentic synthetic standards, to quantify by mass spectrometry four clinically used ceramide species in the NIST (National Institute of Standards and Technology) human blood plasma Standard Reference Material (SRM) 1950, as well as a set of candidate plasma reference materials (RM 8231). Participants either utilized a provided validated method and/or their method of choice. Mean concentration values, and intra- and inter-laboratory coefficients of variation (CV) were calculated using single-point and multi-point calibrations, respectively. These results are the most precise (intra-laboratory CVs ≤ 4.2%) and concordant (inter-laboratory CVs < 14%) community-derived absolute concentration values reported to date for four clinically used ceramides in the commonly analyzed SRM 1950. We demonstrate that calibration using authentic labelled standards dramatically reduces data variability. Furthermore, we show how the use of shared RM can correct systematic quantitative biases and help in harmonizing lipidomics. Collectively, the results from the present study provide a significant knowledge base for translation of lipidomic technologies to future clinical applications that might require the determination of reference intervals (RIs) in various human populations or might need to estimate reference change values (RCV), when analytical variability is a key factor for recall during multiple testing of individuals.

Association between attention-deficit/hyperactivity symptoms and sleep in preschoolers.

INTRODUCTION: Sleep problems are frequent in children with attention-deficit/hyperactivity disorder (ADHD). Some authors have tried to characterize paediatric sleep habits in Portugal, but none has focused on preschool-age children nor attempted to establish their association with ADHD. We aimed to assess the prevalence of ADHD symptoms in preschool-age children and to study their association with sleep habits. MATERIAL AND METHODS: We conducted a cross-sectional study. We distributed questionnaires to a random sample of caregivers of children enrolled in early childhood education centres in Porto. We collected data on sociodemographic characteristics, television watching and outdoor activities. We assessed ADHD symptoms and sleep habits with the Portuguese versions of the Conners' Parents Rating Scale, Revised and the Children's Sleep Habits Questionnaire (CSHQ-PT), respectively. RESULTS: The study included 381 preschoolers (50.90% male). We found high scores for ADHD symptoms in 13.10%, with a higher prevalence in girls (14.40% vs. 11.85%; P = 0.276). In the CSHQ-PT, 45.70% of participants had a mean total score greater than 48, which is the cut-off point applied in the screening of sleep disturbances in the Portuguese population. There was a significant association between high scores for ADHD symptoms and a lower maternal education level (P < 0.001), a shorter sleep duration (P = 0.049), and higher scores on parasomnias (P = 0.019) and sleep disordered breathing (P = 0.002) in CSHQ-PT subscales. CONCLUSIONS: ADHD and sleep disorders are common in preschoolers, in Porto, and this study suggests some clinical correlations between them. Since these interactions are complex and far from being elucidated, further studies are paramount to provide guidance for prevention and managing strategies in younger children at risk for ADHD.

Wilson's Disease: A Prevalence Study in a Portuguese Population.

Introduction Wilson's disease (WD) is a rare and underdiagnosed genetic disorder caused by anomalous tissue copper deposition, and for which epidemiological studies, specifically in Portugal, are scarce. Objectives This study aimed to evaluate the prevalence and incidence of WD and provide a description of its main clinical and laboratory features. Methods A retrospective study was carried out, with a search between 1995 and 2015, of all patients with a minimum follow-up of three months and birth confirmed in the northern region of Portugal, with an estimated population of 3,689,682 inhabitants. Database collection was based on the Portuguese National Health Service's clinical coding system, relying on clinical data from 13 northern Portuguese hospitals, liver biopsy histology results, and hospital prescription records. Clinical and biochemical correlations were statistically assessed using chi-square, Mann-Whitney U, Friedman, and Wilcoxon tests. Results Over the 20-year period, a prevalence of 1:37.000 and an incidence of one per million person-year was found. A total of 94 patients were analyzed, with a slight male predominance (53%), the majority with the onset of clinical manifestations in pediatric age (56%), with a median age at diagnosis of 16.6 years (interquartile range of 12.3-20,.8 years). Most patients presented with predominant liver disease (54.8%), with more than a third with cirrhosis; mixed hepatic and neurological manifestations in 17.9%; and mainly neurological symptoms in 10.7% of the patients. Neurological impairment was strongly associated with delayed development of the manifestations of the disease (p = 0.001) and also a higher detection of Kayser-Fleischer rings (p < 0.001), present in 27.0% of the patients. Regarding therapy, penicillamine has been the most widely used, with adverse reactions reported in 24.8%. At six and 12 months after initiation of therapy, a significant decrease in liver enzymes was found (ALT: p = 0.002; AST: p = 0.002, respectively), but no significant reduction was observed in urinary copper excretion. Conclusion This was one of the first studies regarding WD prevalence in a Portuguese population, contributing to a better understanding of the epidemiology, diagnosis, and management of WD in the northern region of Portugal. WD should be considered in any individual with unexplained hepatic or neurological manifestations, and initial symptoms may manifest at an early age, even in children less than five years old. A high percentage of patients were identified in the early stages of the disease by asymptomatic elevation of transaminases. Following copper chelation therapy, cytolysis markers appear to be more sensitive indicators of treatment response.

Correction: Wilson's Disease: A Prevalence Study in a Portuguese Population.

[This corrects the article DOI: 10.7759/cureus.43718.].

Targeted delivery of alcohol-containing payloads with antibody-drug conjugates.

We herein describe the cell-specific release of alcohol-containing payloads via a sulfatase-sensitive linker in antibody-drug conjugates (ADCs). The linker shows efficient sulfatase-mediated release and high stability in human and mouse plasma. In vitro evaluation demonstrates potent antigen dependent toxicity towards breast cancer cell lines.

The Effect of a Pex3 Mutation on Hearing and Lipid Content of the Inner Ear.

Peroxisome biogenesis disorders (due to PEX gene mutations) are associated with symptoms that range in severity and can lead to early childhood death, but a common feature is hearing impairment. In this study, mice carrying Pex3 mutations were found to show normal auditory development followed by an early-onset progressive increase in auditory response thresholds. The only structural defect detected in the cochlea at four weeks old was the disruption of synapses below inner hair cells. A conditional approach was used to establish that Pex3 expression is required locally within the cochlea for normal hearing, rather than hearing loss being due to systemic effects. A lipidomics analysis of the inner ear revealed a local reduction in plasmalogens in the Pex3 mouse mutants, comparable to the systemic plasmalogen reduction reported in human peroxisome biogenesis disorders. Thus, mice with Pex3 mutations may be a useful tool to understand the physiological basis of peroxisome biogenesis disorders.

Identification and relative quantification of 3-nitrotyrosine residues in fibrinogen nitrated in vitro and fibrinogen from ischemic stroke patient plasma using LC-MS/MS.

Ischemic stroke is one of the leading causes of death and disability worldwide. This acute vascular event interferes with blood supply to the brain and induces a burst of free radicals such as nitric oxide and superoxide, producing peroxynitrite, a precursor of strong nitrating agents. Fibrinogen is one of the most abundant plasma proteins; it plays a role in the hemostatic system, mediating clot formation, which can be affected by nitrotyrosine formation. We hypothesized that nitration of fibrinogen by ONOOH and ONOOCO2- radical products could be one of the early events of the ischemic stroke, and protein-bound 3-nitrotyrosine could be a potential biomarker for diagnosis and/or prognosis of this condition. A targeted mass spectrometry approach was developed to analyze the nitration of fibrinogen and its association with ischemic stroke. First, a comprehensive mapping of 3-nitrotyrosine locations and their relative quantification was performed by LC-MS/MS, using in vitro nitrated fibrinogen samples. Twenty different 3-nitrotyrosine residues were identified on fibrinogen nitrated in vitro, varying with the peroxynitrite tofibrinogen molar ratio used. Nine tyrosine residues that were consistently modified at different treatment ratios were chosen to perform a targeted LC-MS/MS analysis in clinical samples. Enriched fibrinogen fractions from clinical samples from 24 ischemic stroke and 12 patients with non-inflammatory conditions were analysed with this method. Three of the nine tyrosine residues analysed (ßY452, ßY475 and γY380) showed a significant difference between the ischemic stroke and non-inflammatory disease groups. ROC curve analysis suggested an association of these residues either individually or in combination with ischemic stroke. Different tyrosine nitration patterns were also observed in fibrinogen modified in vitro and in vivo, suggesting differences in the nitration process in these situations. This is the first study showing a putative association between the nitration profile of specific tyrosine residues in human fibrinogen and ischemic stroke.

Integrated lipidomics and proteomics reveal cardiolipin alterations, upregulation of HADHA and long chain fatty acids in pancreatic cancer stem cells.

Pancreatic cancer stem cells (PCSCs) play a key role in the aggressiveness of pancreatic ductal adenocarcinomas (PDAC); however, little is known about their signaling and metabolic pathways. Here we show that PCSCs have specific and common proteome and lipidome modulations. PCSCs displayed downregulation of lactate dehydrogenase A chain, and upregulation of trifunctional enzyme subunit alpha. The upregulated proteins of PCSCs are mainly involved in fatty acid (FA) elongation and biosynthesis of unsaturated FAs. Accordingly, lipidomics reveals an increase in long and very long-chain unsaturated FAs, which are products of fatty acid elongase-5 predicted as a key gene. Moreover, lipidomics showed the induction in PCSCs of molecular species of cardiolipin with mixed incorporation of 16:0, 18:1, and 18:2 acyl chains. Our data indicate a crucial role of FA elongation and alteration in cardiolipin acyl chain composition in PCSCs, representing attractive therapeutic targets in PDAC.

BioPAN: a web-based tool to explore mammalian lipidome metabolic pathways on LIPID MAPS.

Lipidomics increasingly describes the quantification using mass spectrometry of all lipids present in a biological sample.  As the power of lipidomics protocols increase, thousands of lipid molecular species from multiple categories can now be profiled in a single experiment.  Observed changes due to biological differences often encompass large numbers of structurally-related lipids, with these being regulated by enzymes from well-known metabolic pathways.  As lipidomics datasets increase in complexity, the interpretation of their results becomes more challenging.  BioPAN addresses this by enabling the researcher to visualise quantitative lipidomics data in the context of known biosynthetic pathways.  BioPAN provides a list of genes, which could be involved in the activation or suppression of enzymes catalysing lipid metabolism in mammalian tissues.

Short-chain lipid peroxidation products form covalent adducts with pyruvate kinase and inhibit its activity in vitro and in breast cancer cells.

Pyruvate kinase catalyses the last step in glycolysis and has been suggested to contribute to the regulation of aerobic glycolysis in cancer cells. It can be inhibited by oxidation of cysteine residues in vitro and in vivo, which is relevant to the more pro-oxidant state in cancer and proliferating tissues. These conditions also favour lipid peroxidation and the formation of electrophilic fragmentation products, including short-chain aldehydes that can covalently modify proteins. However, as yet few studies have investigated their interactions with pyruvate kinase, so we investigated the effects of three different aldehydes, acrolein, malondialdehyde and 4-hydroxy-2(E)-hexenal (HHE), on the structure and activity of the enzyme. Analysis by LC-MS/MS showed unique modification profiles for each aldehyde, but Cys152, Cys423 and Cys474 were the residues most susceptible to electrophilic modification. Analysis of enzymatic activity under these conditions showed that acrolein was the strongest inhibitor, and at incubation times longer than 2 h, pathophysiological concentrations induced significant effects. Treatment of MCF-7 cells with the aldehydes caused similar losses of pyruvate kinase activity to those observed in vitro, and at lower concentrations than those required to cause cell death, with time and dose-dependent effects; acrolein adducts on Cys152 and Cys358 were detected. Cys358 and Cys474 are located at or near the allosteric or active sites, and formation of adducts on these residues probably contributes to loss of activity at low treatment concentrations. This study provides the first detailed analysis of the structure-activity relationship of C3 and C6 aldehydes with pyruvate kinase, and suggests that reactive short-chain aldehydes generated in diseases with an oxidative aetiology or from environmental exposure such as smoking could be involved in the metabolic alterations observed in cancer cells, through alteration of pyruvate kinase activity.

Evaluation of air oxidized PAPC: A multi laboratory study by LC-MS/MS.

Oxidized LDL (oxLDL) has been shown to play a crucial role in the onset and development of cardiovascular disorders. The study of oxLDL, as an initiator of inflammatory cascades, led to the discovery of a variety of oxidized phospholipids (oxPLs) responsible for pro-inflammatory actions. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) is frequently used by the scientific community as a representative oxPL mixture to study the biological effects of oxidized lipids, due to the high abundance of PAPC in human tissues and the biological activities of oxidized arachidonic acids derivatives. Most studies focusing on oxPAPC effects rely on in-house prepared mixtures of oxidized species obtained by exposing PAPC to air oxidation. Here, we described a multi-laboratory evaluation of the compounds in oxPAPC by LC-MS/MS, focusing on the identification and relative quantification of the lipid peroxidation products (LPPs) formed. PAPC was air-oxidized in four laboratories using the same protocol for 0, 48, and 72 h. It was possible to identify 55 different LPPs with unique elemental composition and characterize different structural isomeric species within these. The study showed good intra-sample reproducibility and similar qualitative patterns of oxidation, as the most abundant LPPs were essentially the same between the four laboratories. However, there were substantial differences in the extent of oxidation, i.e. the amount of LPPs relative to unmodified PAPC, at specific time points. This shows the importance of characterizing air-oxidized PAPC preparations before using them for testing biological effects of oxidized lipids, and may explain some variability of effects reported in the literature.

Relación entre los síntomas de déficit de atención/hiperactividad y el sueño en preescolares / Association between attention-deficit/hyperactivity symptoms and sleep in preschoolers

Introducción: Los problemas de sueño son frecuentes en niños con trastorno por déficit de atención/hiperactividad (TDAH). Algunos autores han tratado de caracterizar los hábitos de sueño pediátricos en Portugal, pero ninguno se ha centrado en los niños en edad preescolar ni ha intentado correlacionarlos con el TDAH. El objetivo fue evaluar la prevalencia de los síntomas del TDAH en niños en edad preescolar y estudiar su asociación con los hábitos de sueño. Material y métodos: Estudio transversal mediante la administración de un cuestionario a una muestra aleatoria de cuidadores de niños matriculados en guarderías en Oporto. Se recogieron datos de características sociodemográficas, consumo de televisión y actividades al aire libre. Los síntomas del TDAH y los hábitos de sueño fueron evaluados mediante las versiones portuguesas del Conners’ Parents Rating Scale-Revised y el Children's Sleep Habits Questionnaire (CSHQ-PT), respectivamente. Resultados: El estudio incluyó 381 preescolares (50,90% varones). Se encontraron niveles altos de síntomas de TDAH en el 13,10%, con una prevalencia mayor en las niñas (14,40% vs. 11,85%; p=0,276). El 45,70% tenían una puntuación total en el CSQH-PT superior a 48, que es el punto de corte establecido para el cribado de los trastornos del sueño en la población portuguesa. Se encontró una asociación significativa entre niveles altos de síntomas de TDAH y un nivel educativo materno más bajo (p<0,001), una menor duración del sueño (p=0,049) y mayores puntuaciones en las subescalas de parasomnias (p=0,019) y de trastornos respiratorios del sueño (p=0,002). (AU)

Introduction: Sleep problems are frequent in children with attention-deficit/hyperactivity disorder (ADHD). Some authors have tried to characterize paediatric sleep habits in Portugal, but none has focused on preschool-age children nor attempted to establish their association with ADHD. We aimed to assess the prevalence of ADHD symptoms in preschool-age children and to study their association with sleep habits. Material and methods: We conducted a cross-sectional study. We distributed questionnaires to a random sample of caregivers of children enrolled in early childhood education centres in Porto. We collected data on sociodemographic characteristics, television watching and outdoor activities. We assessed ADHD symptoms and sleep habits with the Portuguese versions of the Conners’ Parents Rating Scale, Revised and the Children's Sleep Habits Questionnaire (CSHQ-PT), respectively. Results: The study included 381 preschoolers (50.90% male). We found high scores for ADHD symptoms in 13.10%, with a higher prevalence in girls (14.40% vs. 11.85%; P=.276). In the CSHQ-PT, 45.70% of participants had a mean total score greater than 48, which is the cut-off point applied in the screening of sleep disturbances in the Portuguese population. There was a significant association between high scores for ADHD symptoms and a lower maternal education level (P<.001), a shorter sleep duration (P=.049), and higher scores on parasomnias (P=.019) and sleep disordered breathing (P=.002) in CSHQ-PT subscales. (AU)