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1.
Int J Lang Commun Disord ; 58(2): 629-650, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36448619

RESUMO

BACKGROUND: Adjectives are essential for communication, conceptual development and academic success. However, they are semantically and syntactically complex and can be particularly challenging for children with Developmental Language Disorder (DLD). Surprisingly, language interventions have not typically focused on this important word class. AIMS: (1) To provide a supportive and accessible primer on adjectives for practitioners; (2) to explore how the SHAPE CODINGTM system can be adapted to support adjective learning in DLD; and (3) to provide practical recommendations on how to support adjective learning in clinical practice and education. METHODS/PROCEDURE: We synthesise linguistic and psychological research on adjective semantics, clinical insights into DLD and pedagogical practice supporting this population. MAIN CONTRIBUTION: We address the lack of specific training in the nature and acquisition of adjectives for speech and language therapists (SLTs) by providing an accessible primer. We also provide an innovative guide detailing how an established metalinguistic intervention might be adapted to support adjective learning. CONCLUSIONS/IMPLICATIONS: Without targeted support for adjective learning, the communicative potential of children with DLD is compromised. Our recommendations can be used across a range of therapeutic and educational contexts to guide SLTs and teaching staff in developing practice in this area. WHAT THIS PAPER ADDS: What is already known on the subject Adjectives are an essential word class needed for effective communication. They are also vital to successfully achieve academic objectives across all curriculum areas. For example, most subjects require children to be able to describe, evaluate, compare and discriminate different events, objects or techniques. Children with Developmental Language Disorder (DLD) have deficits in various domains of language that can affect adjective learning and use. What this paper adds to existing knowledge Despite the importance of adjectives, speech and language therapists (SLTs) and other professionals supporting language development rarely receive specific training regarding their structure and meanings, and how to teach and support their use. This article provides an accessible primer on the many subtypes of adjectives and how these behave syntactically and semantically. It explores how adjective teaching could be enhanced for children with DLD by adapting an established metalinguistic technique and provides practical recommendations for implementing this approach. What are the potential or actual clinical implications of this work? By raising awareness of the complexities of adjectives and providing strategies to support their acquisition by children with DLD, this article will enable SLTs and teaching staff to improve their understanding and practice in this area and, with further research, to develop robust, effective interventions for children with DLD. This will contribute to enhancing the long-term academic, social and employment success of children with DLD.


Assuntos
Transtornos do Desenvolvimento da Linguagem , Idioma , Humanos , Criança , Aprendizagem , Linguística , Desenvolvimento da Linguagem , Terapia da Linguagem/métodos , Transtornos do Desenvolvimento da Linguagem/diagnóstico , Transtornos do Desenvolvimento da Linguagem/terapia , Transtornos do Desenvolvimento da Linguagem/psicologia
2.
Infancy ; 28(1): 158-186, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35993691

RESUMO

Variation in infants' home environment is implicated in their cognitive and psycho-social development. The pandemic has intensified variations in home environments through exacerbating socioeconomic inequalities, and increasing psychological stressors for some families. This study investigates the effects of parental (predominantly maternal) mental health, enriching activities and screen use on 280 24- to 52-month-olds' executive functions, internalising and externalising problems, and pro-social behaviour; with socioeconomic status and social support as contextual factors. Our results indicate that aspects of the home environment are differentially associated with children's cognitive and psycho-social development. Parents who experienced sustained mental distress during the pandemic tended to report higher child externalising and internalising problems, and executive function difficulties at follow-up. Children who spent more time engaged in enriching activities with their parents showed stronger executive functions and social competence six months later. Screen use levels during the first year of the pandemic were not associated with outcomes. To mitigate the risk of persistent negative effects for this 'pandemic generation' of infants, our study highlights the importance of supporting parents' mental health. As our results demonstrate the impact of social support on mental health, investing in support services and interventions promoting building support networks are likely to be beneficial.


Assuntos
COVID-19 , Pandemias , Lactente , Humanos , Criança , Fatores de Proteção , Pais/psicologia , Cognição
3.
J Child Lang ; : 1-17, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36938662

RESUMO

Previous studies have shown that caregivers' sensitive, responsive interactions with young children can boost language development. We explored the association between caregivers' sensitivity and the vocabulary development of their 8-to-36-month-olds during COVID-19 when family routines were unexpectedly disrupted. Measuring caregivers' sensitivity from home interaction videos at three timepoints, we found that children who experienced more-sensitive concurrent interactions had higher receptive and expressive vocabularies (N=100). Children whose caregivers showed more-sensitive interactions at the beginning of the pandemic showed greater expressive vocabulary growth six (but not 12) months later (n=58). Significant associations with receptive vocabulary growth were not observed. Our findings highlight the importance of sensitivity at a time when other positive influences on language development were compromised.

4.
Infancy ; 27(3): 555-581, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35102670

RESUMO

Early executive functions (EFs) lay the foundations for academic and social outcomes. In this parent-report study of 575 UK-based 8- to 36 month olds (218 followed longitudinally), we investigate how variation in the home environment before and during the 2020 pandemic relates to infants' emerging EFs. Parent-infant enriching activities were positively associated with infant Cognitive Executive Function (CEF) (encompassing inhibitory control, working memory, cognitive flexibility). During the most-restrictive UK lockdown-but not subsequently-socioeconomic status (SES) was positively associated with levels of parent-infant enriching activities. Parents who regard fostering early learning, affection, and attachment as important were more likely to engage in parent-infant enriching activities, yet there was no significant pathway from parental attitudes or SES to CEF via activities. Infant screen use was negatively associated with CEF and Regulation. Screen use fully mediated the effect of SES on CEF, and partially mediated the effect of SES on regulation. Parental attitudes toward early learning, affection, and attachment did not significantly influence screen use. These results indicate that although parental attitudes influence the development of early EFs, interventions targeting attitudes as a means of increasing enriching activities, and thus EF are likely to be less effective than reducing barriers to engaging in enriching activities.


Assuntos
COVID-19 , Função Executiva , Atitude , Controle de Doenças Transmissíveis , Função Executiva/fisiologia , Humanos , Lactente , Pandemias , Pais , Classe Social
5.
J Psycholinguist Res ; 51(5): 933-955, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35556197

RESUMO

Addressees use information from specific speakers' previous discourse to make predictions about incoming linguistic material and to restrict the choice of potential interpretations. In this way, speaker specificity has been shown to be an influential factor in language processing across several domains e.g., spoken word recognition, sentence processing, and pragmatics. However, its influence on semantic disambiguation has received little attention to date. Using an exposure-test design and visual world eye tracking, we examined the effect of speaker-specific literal vs. nonliteral style on the disambiguation of metaphorical polysemes such as 'fork', 'head', and 'mouse'. Eye movement data revealed that when interpreting polysemous words with a literal and a nonliteral meaning, addressees showed a late-stage preference for the literal meaning in response to a nonliteral speaker. We interpret this as reflecting an indeterminacy in the intended meaning in this condition, as well as the influence of meaning dominance cues at later stages of processing. Response data revealed that addressees then ultimately resolved to the literal target in 90% of trials. These results suggest that addressees consider a range of senses in the earlier stages of processing, and that speaker style is a contextual determinant in semantic processing.


Assuntos
Sinais (Psicologia) , Semântica , Humanos , Idioma , Linguística , Movimentos Oculares
6.
Infant Child Dev ; 30(4): e2241, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34220356

RESUMO

High-quality, centre-based education and care during the early years benefit cognitive development, especially in children from disadvantaged backgrounds. During the COVID-19 pandemic and its associated lockdowns, access to early childhood education and care (ECEC) was disrupted. We investigate how this period affected the developmental advantages typically offered by ECEC. Using parent-report data from 189 families living in the UK, we explore associations between time spent in ECEC by 8-to-36-month-olds, their socioeconomic background, and their growth in language and executive functions between Spring and Winter 2020. Receptive vocabulary growth was greater in children who continued to attend ECEC during the period, with a stronger positive effect for children from less advantaged backgrounds. The growth of cognitive executive functions (CEFs) was boosted by ECEC attendance during the period, regardless of socioeconomic background. Our findings highlight the importance of high-quality ECEC for the development of key skills and for levelling socioeconomic inequalities.

7.
Phys Chem Chem Phys ; 22(34): 18976-18988, 2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32648863

RESUMO

The chemical and structural nature of potassium compounds involved in catalytic soot oxidation have been studied by a combination of temperature programmed oxidation and operando potassium K-edge X-ray absorption spectroscopy experiments. These experiments are the first known operando studies using tender X-rays (∼3.6 keV) under high temperature oxidation reaction conditions. X-ray absorption near edge structure analysis of K2CO3/Al2O3 catalysts during heating shows that, at temperatures between 100 and 200 °C, potassium species undergo a structural change from an initial hydrated K2CO3·xH2O and KHCO3 mixture to well-defined K2CO3. As the catalyst is heated from 200 °C to 600 °C, a feature associated with multiple scattering shifts to lower energy, indicating increased K2CO3 dispersion, due to its mobility at high reaction temperature. This shift was noted to be greater in samples containing soot than in control experiments without soot and can be attributed to enhanced mobility of the K2CO3, due to the interaction between soot and potassium species. No potassium species except K2CO3 could be defined during reactions, which excludes a potential reaction mechanism in which carbonate ions are the active soot-oxidising species. Simulations of K-edge absorption near edge structures were performed to rationalise the observed changes seen. Findings showed that cluster size, unit cell distortions and variation in the distribution of potassium crystallographic sites influenced the simulated spectra of K2CO3. While further simulation studies are required for a more complete understanding, the current results support the hypothesis that changes in the local structure on dispersion can influence the observed spectra. Ex situ characterisation was carried out on the fresh and used catalyst, by X-ray diffraction and X-ray photoelectron spectroscopy, which indicated changes to the carbonate species, in line with the X-ray absorption spectroscopy experiments.

8.
J Child Lang ; 47(1): 159-185, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31232261

RESUMO

Adjectives are essential for describing and differentiating concepts. However, they have a protracted development relative to other word classes. Here we measure three- and four-year-olds' exposure to adjectives across a range of interactive and socioeconomic contexts to: (i) measure the syntactic, semantic, and pragmatic variability of adjectives in child-directed speech (CDS); and (ii) investigate how features of the input might scaffold adjective acquisition. In our novel corpus of UK English, adjectives occurred more frequently in prenominal than in postnominal (predicative) syntactic frames, though postnominal frames were more frequent for less-familiar adjectives. They occurred much more frequently with a descriptive than a contrastive function, especially for less-familiar adjectives. Our findings present a partial mismatch between the forms of adjectives found in real-world CDS and those forms that have been shown to be more useful for learning. We discuss implications for models of adjective acquisition and for clinical practice.


Assuntos
Desenvolvimento da Linguagem , Idioma , Relações Mãe-Filho , Fala , Livros , Linguagem Infantil , Pré-Escolar , Família , Feminino , Humanos , Aprendizagem , Masculino , Jogos e Brinquedos , Semântica , Classe Social
9.
J Child Lang ; 47(3): 655-679, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31858950

RESUMO

The ability to make inferences is essential for effective language comprehension. While inferencing training benefits reading comprehension in school-aged children (see Elleman, 2017, for a review), we do not yet know whether it is beneficial to support the development of these skills prior to school entry. In a pre-registered randomised controlled trial, we evaluated the efficacy of a parent-delivered intervention intended to promote four-year-olds' oral inferencing skills during shared book-reading. One hundred children from socioeconomically diverse backgrounds were randomly assigned to inferencing training or an active control condition of daily maths activities. The training was found to have no effect on inferencing. However, inferencing measures were highly correlated with children's baseline language ability. This suggests that a more effective approach to scaffolding inferencing in the preschool years might be to focus on promoting vocabulary to develop richer and stronger semantic networks.


Assuntos
Livros , Formação de Conceito , Poder Familiar , Leitura , Vocabulário , Aptidão , Pré-Escolar , Compreensão , Feminino , Humanos , Masculino , Matemática , Pais , Semântica , Pensamento , Aprendizagem Verbal
10.
Can Psychol ; 61(4): 349-363, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34219905

RESUMO

The field of infancy research faces a difficult challenge: some questions require samples that are simply too large for any one lab to recruit and test. ManyBabies aims to address this problem by forming large-scale collaborations on key theoretical questions in developmental science, while promoting the uptake of Open Science practices. Here, we look back on the first project completed under the ManyBabies umbrella - ManyBabies 1 - which tested the development of infant-directed speech preference. Our goal is to share the lessons learned over the course of the project and to articulate our vision for the role of large-scale collaborations in the field. First, we consider the decisions made in scaling up experimental research for a collaboration involving 100+ researchers and 70+ labs. Next, we discuss successes and challenges over the course of the project, including: protocol design and implementation, data analysis, organizational structures and collaborative workflows, securing funding, and encouraging broad participation in the project. Finally, we discuss the benefits we see both in ongoing ManyBabies projects and in future large-scale collaborations in general, with a particular eye towards developing best practices and increasing growth and diversity in infancy research and psychological science in general. Throughout the paper, we include first-hand narrative experiences, in order to illustrate the perspectives of researchers playing different roles within the project. While this project focused on the unique challenges of infant research, many of the insights we gained can be applied to large-scale collaborations across the broader field of psychology.

11.
J Child Lang ; 45(5): 1116-1143, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29739488

RESUMO

Children's ability to refer is underpinned by their developing cognitive skills. Using a production task (n = 57), we examined pre-articulatory visual fixations to contrast objects (e.g., to a large apple when the target was a small one) to investigate how visual scanning drives informativeness across development. Eye-movements reveal that although four-year-olds fixate contrast objects to a similar extent as seven-year-olds and adults, this does not result in explicit referential informativeness. Instead, four-year-olds frequently omit distinguishing information from their referring expressions regardless of the comprehensiveness of their visual scan. In contrast, older children make greater use of information gleaned from their visual inspections, like adults. Thus, we find a barrier not to the incidence of contrast fixations by younger children, but to their use of them in referential informativeness. We recommend that follow-up work investigates whether younger children's immature executive skills prevent them from describing referents in relation to contrast objects.


Assuntos
Desenvolvimento Infantil , Cognição , Fixação Ocular , Adolescente , Criança , Pré-Escolar , Medições dos Movimentos Oculares , Movimentos Oculares , Feminino , Humanos , Masculino , Percepção Visual , Adulto Jovem
12.
J Exp Child Psychol ; 144: 98-113, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26716575

RESUMO

Specific language impairment (SLI) has traditionally been characterized as a deficit of structural language (specifically grammar), with relative strengths in pragmatics. In this study, comprehensive assessment of production, comprehension, and metalinguistic judgment of referring expressions revealed that children with SLI have weaknesses in both structural and pragmatic language skills relative to age-matched peers. Correlational analyses highlight a relationship between their performance on the experimental tasks and their structural language ability. Despite their poor performance on the production and comprehension tasks, children with SLI were able to recognize pragmatically under-informative reference relative to other types of utterance, although they imposed a less severe penalty on such expressions than typically developing peers, a pattern that supports the pragmatic tolerance account. Our novel methodology (which probed structural abilities from both the speaker's and hearer's perspectives as well as metalinguistic and pragmatic skills in the same sample) challenges the assumption that pragmatic errors stem from deficits in social cognition and instead supports recent findings suggesting that when the impact of structural language is isolated, pragmatic deficits may be resolved.


Assuntos
Compreensão/fisiologia , Transtornos do Desenvolvimento da Linguagem/fisiopatologia , Idioma , Metacognição/fisiologia , Transtorno de Comunicação Social/fisiopatologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino
13.
JCPP Adv ; 3(4): e12190, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38054058

RESUMO

Background: How often a child naps, during infancy, is believed to reflect both intrinsic factors, that is, the need of an immature brain to consolidate information soon after it is acquired, and environmental factors. Difficulty accounting for important environmental factors that interfere with a child's sleep needs (e.g., attending daycare) has clouded our ability to understand the role of intrinsic drivers of napping frequency. Methods: Here we investigate sleep patterns in association with two measures of cognitive ability, vocabulary size, measured with the Oxford-Communicative Development Inventory (N = 298) and cognitive executive functions (EF), measured with the Early EF Questionnaire (N = 463), in a cohort of 8-38-month-olds. Importantly, because of the social distancing measures imposed during the Covid-19 Spring 2020 lockdown, in the UK, measures of sleep were taken when children did not access daycare settings. Results: We find that children with more frequent but shorter naps than expected for their age had lower concurrent receptive vocabularies, lower cognitive EF and a slower increase in expressive vocabulary from spring to winter 2020, when age, sex, and SES were accounted for. The negative association between vocabulary and frequency of naps became stronger with age. Conclusions: These findings suggest that the structure of daytime sleep is an indicator of cognitive development and highlight the importance of considering environmental perturbations and age when investigating developmental correlates of sleep.

14.
Mol Genet Metab Rep ; 37: 101020, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38053940

RESUMO

Ornithine transcarbamylase deficiency (OTCD) is an X-linked defect of ureagenesis and the most common urea cycle disorder. Patients present with hyperammonemia causing neurological symptoms, which can lead to coma and death. Liver transplantation (LT) is the only curative therapy, but has several limitations including organ shortage, significant morbidity and requirement of lifelong immunosuppression. This study aims to identify the characteristics and outcomes of patients who underwent LT for OTCD. We conducted a retrospective study for OTCD patients from 5 UK centres receiving LT in 3 transplantation centres between 2010 and 2022. Patients' demographics, family history, initial presentation, age at LT, graft type and pre- and post-LT clinical, metabolic, and neurocognitive profile were collected from medical records. A total of 20 OTCD patients (11 males, 9 females) were enrolled in this study. 6/20 had neonatal and 14/20 late-onset presentation. 2/20 patients had positive family history for OTCD and one of them was diagnosed antenatally and received prospective treatment. All patients were managed with standard of care based on protein-restricted diet, ammonia scavengers and supplementation with arginine and/or citrulline before LT. 15/20 patients had neurodevelopmental problems before LT. The indication for LT was presence (or family history) of recurrent metabolic decompensations occurring despite standard medical therapy leading to neurodisability and quality of life impairment. Median age at LT was 10.5 months (6-24) and 66 months (35-156) in neonatal and late onset patients, respectively. 15/20 patients had deceased donor LT (DDLT) and 5/20 had living related donor LT (LDLT). Overall survival was 95% with one patient dying 6 h after LT. 13/20 had complications after LT and 2/20 patients required re-transplantation. All patients discontinued dietary restriction and ammonia scavengers after LT and remained metabolically stable. Patients who had neurodevelopmental problems before LT persisted to have difficulties after LT. 1/5 patients who was reported to have normal neurodevelopment before LT developed behavioural problems after LT, while the remaining 4 maintained their abilities without any reported issues. LT was found to be effective in correcting the metabolic defect, eliminates the risk of hyperammonemia and prolongs patients' survival.

15.
Sci Rep ; 12(1): 2015, 2022 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-35132065

RESUMO

Older children with online schooling requirements, unsurprisingly, were reported to have increased screen time during the first COVID-19 lockdown in many countries. Here, we ask whether younger children with no similar online schooling requirements also had increased screen time during lockdown. We examined children's screen time during the first COVID-19 lockdown in a large cohort (n = 2209) of 8-to-36-month-olds sampled from 15 labs across 12 countries. Caregivers reported that toddlers with no online schooling requirements were exposed to more screen time during lockdown than before lockdown. While this was exacerbated for countries with longer lockdowns, there was no evidence that the increase in screen time during lockdown was associated with socio-demographic variables, such as child age and socio-economic status (SES). However, screen time during lockdown was negatively associated with SES and positively associated with child age, caregiver screen time, and attitudes towards children's screen time. The results highlight the impact of the COVID-19 lockdown on young children's screen time.


Assuntos
COVID-19/epidemiologia , COVID-19/prevenção & controle , Pandemias/prevenção & controle , Quarentena/métodos , SARS-CoV-2 , Tempo de Tela , Fatores Etários , COVID-19/virologia , Cuidadores , Pré-Escolar , Estudos de Coortes , Escolaridade , Feminino , Humanos , Lactente , Masculino , Pais
16.
Cognition ; 212: 104707, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33957498

RESUMO

Combining information from adjectives with the nouns they modify is essential for comprehension. Previous research suggests that preschoolers do not always integrate adjectives and nouns, and may instead over-rely on noun information when processing referring expressions (Fernald, Thorpe, & Marchman, 2010; Thorpe, Baumgartner, & Fernald, 2006). This disjointed processing has implications for pragmatics, apparently preventing under-fives from making contrastive inferences (Huang & Snedeker, 2013). Using a novel experimental design that allows preschoolers time to demonstrate their abilities in adjective-noun integration and in contrastive inference, two visual world experiments investigate how English-speaking three-year-olds (N = 73, Mage = 44 months) process size adjectives across syntactic (prenominal; postnominal) and pragmatic (descriptive; contrastive) contexts. We show that preschoolers are able to integrate adjectives and nouns to resolve reference accurately by the end of the referring expression, in a variety of pragmatic and syntactic contexts and in the presence of multiple distractors. We reveal for the first time that they can contrastively infer, given a slowed speed of presentation and visually salient size contrasts. Our findings provide evidence for a continuity in the development of pragmatic skills, which do not appear to be linked to children's language proficiency or speed of processing.


Assuntos
Compreensão , Idioma , Criança , Pré-Escolar , Humanos , Desenvolvimento da Linguagem
18.
Acta Psychol (Amst) ; 178: 87-99, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28628785

RESUMO

Variation in referential form has traditionally been accounted for by theoretical frameworks focusing on linguistic and discourse features. Despite the explosion of interest in eye tracking methods in psycholinguistics, the role of visual scanning behaviour in informative reference production is yet to be comprehensively investigated. Here we examine the relationship between speakers' fixations to relevant referents and the form of the referring expressions they produce. Overall, speakers were fully informative across simple and (to a lesser extent) more complex displays, providing appropriately modified referring expressions to enable their addressee to locate the target object. Analysis of contrast fixations revealed that looking at a contrast object boosts but is not essential for full informativeness. Contrast fixations which take place immediately before speaking provide the greatest boost. Informative referring expressions were also associated with later speech onsets than underinformative ones. Based on the finding that fixations during speech planning facilitate but do not fully predict informative referring, direct visual scanning is ruled out as a prerequisite for informativeness. Instead, pragmatic expectations of informativeness may play a more important role. Results are consistent with a goal-based link between eye movements and language processing, here applied for the first time to production processes.


Assuntos
Comunicação , Sensibilidades de Contraste/fisiologia , Idioma , Fala , Movimentos Oculares/fisiologia , Feminino , Humanos , Linguística , Masculino , Psicolinguística , Adulto Jovem
19.
Science ; 355(6332): 1399-1403, 2017 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-28360324

RESUMO

There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species.

20.
Diabetes ; 53(6): 1535-42, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15161758

RESUMO

Hypoglycemia produces electrocardiographic QTc lengthening, a predictor of arrhythmia risk and sudden death. This results from both sympatho-adrenal activation and a lowered serum potassium. It has been suggested that cardiac autonomic neuropathy (CAN) might indicate those who are at particular risk. We tested this hypothesis in 28 adults with type 1 diabetes and 8 nondiabetic control subjects. After standard tests of autonomic function and baroreflex sensitivity (BRS) measurement, diabetic participants were divided into three groups: 1) CAN- with normal BRS (BRS+; n = 10), 2) CAN- with impaired BRS (BRS-; n = 9), and 3) CAN+ (n = 9). QTc was then measured during controlled hypoglycemia (2.5 mmol/l) using a hyperinsulinemic clamp. Mean (+/-SE) QTc lengthened from 377 +/- 9 ms (baseline) to a maximum during hypoglycemia of 439 +/- 13 ms in BRS+ subjects and from 378 +/- 5 to 439 +/- 10 ms in control subjects. Peak QTc tended to be lower in CAN+ (baseline, 383 +/- 6; maximum, 408 +/- 10) and BRS- groups (baseline, 380 +/- 8; maximum, 421 +/- 11; F = 1.7, P = 0.18). Peak epinephrine concentrations (nmol/l) were 3.1 +/- 0.8 (BRS+), 2.6 +/- 0.5 (BRS-), 1.4 +/- 0.3 (CAN+), and 5.7 +/- 0.8 (control subjects). These data do not indicate that those with CAN are at particular risk for abnormal cardiac repolarization during hypoglycemia. Indeed, they suggest that such patients may be relatively protected, perhaps as a result of attenuated sympatho-adrenal responses.


Assuntos
Doenças do Sistema Nervoso Autônomo/etiologia , Doenças do Sistema Nervoso Autônomo/fisiopatologia , Diabetes Mellitus Tipo 1/complicações , Neuropatias Diabéticas/etiologia , Neuropatias Diabéticas/fisiopatologia , Coração/fisiopatologia , Hipoglicemia/etiologia , Adulto , Sistema Nervoso Autônomo/fisiopatologia , Pressão Sanguínea , Estudos de Casos e Controles , Eletrocardiografia , Epinefrina/sangue , Feminino , Técnica Clamp de Glucose , Humanos , Masculino , Norepinefrina/sangue , Potássio/sangue
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