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1.
Aust N Z J Psychiatry ; 57(2): 291-301, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-35652302

RESUMO

OBJECTIVES: Suicide is a leading cause of maternal mortality. Suicidality during and around the time of pregnancy can have detrimental impacts on a child's development and outcomes. This paper examines prevalence, demographic characteristics, and timing of initial contact with first responders and health services for a cohort of women who experienced suicidality during and around the time of pregnancy. METHODS: Findings are drawn from the Partners in Prevention (PiP) study, a population-wide linked data set of suicide-related attendances by police or paramedics in Queensland, Australia. A sub-cohort of women was identified, who were between 6 months preconception and 2 years postpartum at the time of a suicide-related contact with police or paramedics (PiP-Maternal). Findings are compared to other girls and women who had a suicide-related contact with police or paramedics (PiP-Female). Prevalence, demographic characteristics, timing of contact with first responders and health services, re-presentations, and mortality are reported. RESULTS: The PiP-Maternal cohort comprised 3020 individuals and 3400 births. Women in the PiP-Maternal cohort were younger, more likely to be of Aboriginal and/or Torres Strait Islander descent and live outside of a major city than the PiP-Female cohort. There were high rates of out-of-hours calls to police and ambulance, and similar perceived seriousness of the call between women in the PiP-Maternal and PiP-Female cohorts. Women in the PiP-Maternal cohort were less likely to be admitted to an emergency department within 24 hours, even after matching on covariates. Prevalence of suicidality for women who were pregnant and up to 2 years postpartum was 1.32% (95% CI = [1.27, 1.37]). CONCLUSION: Vulnerabilities and high rates of contact with police or paramedics, coupled with lower levels of follow-up, highlight the critical need to improve service responses for women with mental health needs during these phases of life.


Assuntos
Socorristas , Suicídio , Gravidez , Criança , Feminino , Humanos , Mães , Prevalência , Serviços de Saúde
2.
Aust N Z J Psychiatry ; 56(2): 144-153, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33904321

RESUMO

BACKGROUND AND AIMS: Police and paramedics play a crucial role in responding to suicide crises in the community. However, little is known about the nature, extent, precipitating factors, pathways and outcomes of a suicide-related call to emergency services and what responses will most effectively and compassionately meet the needs of those in crisis. Partners in Prevention: Understanding and Enhancing First Responses to Suicide Crisis Situations (PiP) was established to address these knowledge gaps. METHODS: This article describes (1) the methodology used to construct the PiP dataset, a population-wide linked dataset that investigates the characteristics and health pathways of individuals in Queensland who were the subject of a suicide-related call to police or paramedics; and (2) preliminary findings on service demand, demographics and health services utilisation. RESULTS: We identified 219,164 suicide-related calls to Queensland Police Service or Queensland Ambulance Service that were made over the 3-year period 1 February 2014 to 31 January 2017. A total of 70,893 individuals were identifiable via records linkage. The cohort linked to more than 7,000,000 health records. We estimated that police or paramedics in Queensland received on average 209 calls per day, with increases year on year over the study period. Analysis of demographic data highlighted the heterogeneous nature of this cohort and important demographic variations between individuals in contact with police versus ambulance services. DISCUSSION: The PiP dataset provides a strong foundation for a multi-modal dataset that can be built on over time, both cross-sectionally and longitudinally. Further linkages to Medicare Benefits Schedule, Pharmaceutical Benefits Scheme and social care datasets are planned. CONCLUSION: Detailed population-level analysis that data linkage can provide is critical to improving understanding and responses to suicide crisis situations. The PiP study is a world first and provides a unique opportunity to improve responses to this public health problem.


Assuntos
Programas Nacionais de Saúde , Prevenção do Suicídio , Idoso , Austrália , Humanos , Armazenamento e Recuperação da Informação , Queensland/epidemiologia
3.
Arch Womens Ment Health ; 24(4): 579-593, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33742281

RESUMO

The purpose of this scoping review was to summarize research that uses linked data to examine peripartum suicidal behaviours and critically appraise studies to identify evidence gaps and future research priorities. A systematic search of PubMed, Scopus, and grey literature was undertaken to identify data linkage studies that examined suicidal behaviours among women in the peripartum period. All articles available through PubMed and Scopus up until the search date of 26 September 2019 were deemed eligible for inclusion. A grey literature search was also undertaken, through the Google search engine, on 11 November 2019. Studies were analysed descriptively and synthesized qualitatively. Eighteen studies were identified that met inclusion criteria. All studies examined the incidence of suicidal behaviours. Twelve studies examined sociodemographic correlates, associations, or risk factors, and nine studies examined mental health. There was a high degree of variability regarding how both peripartum status and suicidal behaviours were defined. Few studies used data linkage to examine suicidal behaviours from a health services or social services perspective. The evidence base could benefit from conceptual clarity and standardization of constructs regarding suicidal behaviours in the peripartum period, to enable meaningful synthesis of results across studies. Data linkage can be used to improve understandings of risk factors and pathways. It can also be harnessed to examine both health and social services utilization, to inform coordinated multi-sectoral interventions and care pathways for women and their children.


Assuntos
Período Periparto , Ideação Suicida , Criança , Feminino , Humanos , Armazenamento e Recuperação da Informação , Saúde Mental , Fatores de Risco
4.
Emerg Med Australas ; 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38495001

RESUMO

OBJECTIVE: Suicide is a leading cause of death in children and adolescents worldwide and a major public health concern. While suicidal behaviours place a significant demand on mental health and emergency services, data regarding suicide-related contacts with police and paramedics are an underutilised resource. The aim of the present study was to identify the demographic profile of young individuals (aged 5-17) and had a suicide-related contact with police or paramedics in Queensland (Australia). METHODS: The present study utilised a population-wide linked dataset, including data from police and paramedics and health administrative data, between 1 February 2013 and 31 January 2018. RESULTS: The identified cohort of 7929 children had a median age of 15 years and mainly comprised females (63.2%). Over the study period, 64 children died, most by suicide (76.6%). Less than a third of the cohort were responsible for almost two-thirds of the total number of contacts with police or paramedics. CONCLUSION: Findings provide a comprehensive profile of children and adolescents in suicidal crisis and highlight the substantial number of interactions that occur with police and paramedics. Due to the way the linked dataset was constructed, it must be assumed that the number of young persons in suicidal crisis is higher. Findings highlight the value of considering pre-hospital alternatives to presenting to emergency departments (EDs) for this cohort, to reduce impost on EDs and improve outcomes. Further examination of re-presentations by young persons is warranted to inform prevention and intervention strategies.

5.
Front Psychiatry ; 14: 1207103, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37928913

RESUMO

The National Strategic Framework for Aboriginal and Torres Strait Islander Peoples' Mental Health and Social and Emotional Wellbeing identifies building a strong Aboriginal and Torres Strait Islander led evidence-base to inform care as a key priority. Aboriginal and/or Torres Strait Islander adolescents in contact with the criminal justice system are a highly vulnerable group of Australians, with substantial unmet needs. There is limited evidence to inform culturally appropriate models of care that meet the social and emotional wellbeing needs of justice-involved Aboriginal and/or Torres Strait Islander adolescents. This project aims to develop, implement and evaluate an in-reach and community transitional model of social and emotional wellbeing care for Aboriginal and/or Torres Strait Islander adolescents (10-17 years old) who experience detention through close engagement with Aboriginal and/or Torres Strait Islander youth, Elders, researchers, practitioners and community members, and by drawing on culturally informed practice and knowledge systems. The project is based on a multi-level mixed methods design, with a strong focus on ongoing project evaluation (based on the Ngaa-bi-nya framework) and co-design. Co-design is facilitated through culturally safe and trauma informed participatory processes based on development of strong partnerships from project initiative, design, implementation and evaluation. Application of the landscape domain of the Ngaa-bi-nya framework for Aboriginal and Torres Strait Islander program evaluation will be explored in Phase one. Aboriginal and Torres Strait Islander adolescents with experience in detention will be engaged through one-on-one interviews with data collection through the Growth and Empowerment Measure (GEM) Youth (which will be adapted from the adult version and validated as part of this study), the Kessler Psychological Distress Scale (K-10), questions around alcohol and drug use, and narrative interviews exploring experience. Qualitative data will be analyzed using an inductive thematic approach, structured within the framework of the Ngaa-bi-nya landscape prompts. Quantitative data will be analyzed using descriptive statistics to provide a profile of the cohort. Findings from Phase one will be used to inform the development of a model of social and emotional wellbeing care that will be implemented and evaluated in Phase two.

6.
BMJ Open ; 12(12): e061695, 2022 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-36549725

RESUMO

INTRODUCTION: Past research has shown that construction industry workers are at an elevated risk of suicide, however, to date, no study has examined in detail the characteristics of individuals who work in the construction industry and experience distress. This research aims to understand the characteristics, including sociodemographic characteristics, health services utilisation and contacts with non-clinical services, of individuals working within the construction industry and who experience distress, and to quantify the costs and benefits of different help-seeking pathways. METHODS AND ANALYSIS: This study is a data linkage study, based on routinely collected administrative data from construction industry organisations and Queensland Health (QH). Expected outcomes include prevalence of distress, articulated to non-clinical construction industry agencies, descriptive findings on characteristics and help-seeking pathways and health economic analysis. Individuals who experienced distress but who did not contact any of the participating construction industry organisations will not be part of this research. ETHICS AND DISSEMINATION: This data linkage study was approved by Human Research Ethics Committee of The University of Queensland (2021/HE001885). Findings will be presented descriptively to describe the cohort as a whole and stratified by key demographic characteristics, and to provide estimates of prevalence of distress, including timing, frequency and type of contacts. In addition, health economic analysis will be undertaken. Dissemination of findings will be undertaken following consultation of all project investigators, construction industry organisations and peer-led interest groups and lived-experience organisations to ensure translation merit of all findings. Results will be published as peer-reviewed journal articles and publicly available reports.


Assuntos
Indústria da Construção , Suicídio , Humanos , Custos e Análise de Custo , Prevalência , Armazenamento e Recuperação da Informação
7.
Artigo em Inglês | MEDLINE | ID: mdl-34201510

RESUMO

MATES in Construction (MATES) is a multimodal, peer-led, workplace suicide prevention and early intervention program developed to reduce the risk of suicide among construction industry workers through active facilitation of appropriate support. The MATES case management model provides an example of a nonclinical service for meeting the needs of individuals in the construction industry who, while at elevated risk of mental health problems and suicidality, are traditionally less likely to seek help. The aim of this research was to conduct an evaluation of the MATES case management database to quantify service demand, and to examine the demographic, occupational profile, presenting issues, referral pathways, and perceived benefit of case management among individuals who used this service. The research reports on routinely collected data from the Queensland MATES case management database, which contains records on 3759 individuals collected over the period 2010-2018, and findings from a small and opportunistic exit survey undertaken with 14 clients in 2019. Overall, findings suggest that the demand for case management through MATES has increased significantly and that clients felt that their needs and concerns were appropriately addressed. The most common presenting issues were relationship, work, and family problems, suicide, and mental health concerns. Findings confirm that causes of distress extend beyond the realm of mental disorder and span a range of psychosocial issues. Significantly, it offers an approach that may divert individuals in crisis away from presenting to over-run emergency departments, and towards services that are more equipped to meet their individual needs.


Assuntos
Indústria da Construção , Prevenção do Suicídio , Administração de Caso , Humanos , Queensland , Encaminhamento e Consulta
8.
Crisis ; 42(5): 386-395, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33241741

RESUMO

Background: Police and paramedics are often the first to respond to individuals in suicide crisis and have an important role to play in facilitating optimal care pathways. Yet, little evidence exists to inform these responses. Data linkage provides one approach to examining this knowledge gap. Aim: We identified studies that examined suicide behaviors and linked to police or ambulance data. Method: A systematic search of PubMed and Scopus was undertaken to identify data linkage studies that: (1) examined suicide behaviors, and (2) included police or ambulance data. Studies were reviewed to identify: aims; suicide behaviors examined; how these were measured; how the cohort was defined; topic area; and what datasets were linked. Results: Eight studies met the inclusion criteria. Six studies included police data, and two studies included ambulance data. No study included both. Two topic areas were identified: (1) suicide-related contact with police or ambulance services; and (2) associations between suicidal behaviors and violence, victimization, and criminality. Limitations: Limitations to the review include the potential to have missed studies that investigated or reported on suicidality under the guise of mental health problems; complexities and nuances arising from the role of police data in coronial investigations; and limitations in the number of databases searched. Conclusion: Police and ambulance data represent a currently underutilized source of valuable information relevant to suicide crises, and further research should aim to address this gap.


Assuntos
Polícia , Suicídio , Pessoal Técnico de Saúde , Ambulâncias , Humanos , Ideação Suicida
9.
Trends Biochem Sci ; 28(11): 605-11, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14607091

RESUMO

Over 150 mutations with documented pathogenicity have been identified within the human mitochondrial genome. More than half of the disease-related mutations are located within tRNA genes, a remarkable trend, given that these sequences comprise only 10% of the genome. The discovery of diseases correlated with mitochondrial tRNA mutations provides the first example of a class of pathologies related to RNA function, and the study of these tRNAs provides an interesting opportunity to explore the relationship between physiology and tRNA function. Investigations of both cellular and molecular effects have provided important insights into the structural and functional defects caused by the mutations. The picture that emerges from varied studies is that the effects of tRNA mutations are probably multifaceted and complex, but can be traced to the destabilization of structural features that destroy the native tRNA fold required for all aspects of function.


Assuntos
Mitocôndrias/genética , Doenças Mitocondriais/genética , Mutação , RNA de Transferência/química , RNA de Transferência/fisiologia , RNA/genética , Animais , Sequência de Bases , Humanos , Doenças Mitocondriais/etiologia , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Polimorfismo Genético , RNA Mitocondrial , Relação Estrutura-Atividade
10.
Cortex ; 117: 217-227, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30999213

RESUMO

Under natural viewing conditions, visual stimuli are often obscured by occluding surfaces. To aid object recognition, the visual system actively reconstructs the missing information, as exemplified in the classic Kanizsa illusion, a phenomenon termed "modal completion". Single-cell recordings in monkeys have shown that neurons in early visual cortex respond to illusory contours, but it has proven difficult to measure the neural correlates of modal completion in humans. We used electroencephalography (EEG) to measure steady-state visual-evoked potentials (SSVEPs) from disks with quarter segments removed to induce an illusory shape (or rotated to eliminate the illusory square in control trials). Opposing pairs of inducers were tagged with one of two flicker frequencies (2.5 or 4 Hz). During stimulus presentations, participants performed an attention task at fixation that required them to judge the orientation of a briefly flashed central bar while ignoring congruent (same orientation) or incongruent (different orientation) flanker bars that appeared on or off the illusory surface. Importantly, the occurrence of any illusory shape was never task relevant. Frequency-based analyses revealed that SSVEP amplitudes were reliably enhanced for trials in which an illusory square appeared, relative to control trials, at 4, 5 and 8 Hz and at an intermodulation frequency of 13 Hz. Participants' reaction times in the flanker task were significantly slower for incongruent versus congruent trials, and this distractor interference effect occurred only in the presence of an illusory surface and not in the control condition. Our results reveal a robust neural correlate of modal completion in the human visual system and provide evidence that visual completion can affect attentional control processes as deployed in a flanker task.


Assuntos
Atenção/fisiologia , Potenciais Evocados Visuais/fisiologia , Percepção de Forma/fisiologia , Ilusões/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Estimulação Luminosa , Tempo de Reação/fisiologia , Adulto Jovem
11.
Neuropsychologia ; 125: 70-80, 2019 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-30711611

RESUMO

Our perception of illusory shapes, such as the classic Kanizsa triangle, is thought to reflect the visual system's capacity to fill in missing information associated with fragmented or partially occluded objects. Previous work has suggested that such 'modal' filling-in arises at relatively early stages of visual processing, prior to the allocation of focused attention, but few studies have examined whether attention influences neural responses to illusory shapes. Here we asked whether spatial attention affects neural activity evoked by illusory shapes by having participants focus on stimuli presented in one visual field (left or right), while ignoring those on the other side. In two separate experiments, we used electroencephalography (EEG) to measure steady-state visual evoked potentials (SSVEPs; Experiment 1) and event-related potentials (ERPs; Experiment 2), elicited by a Kanizsa square in one hemifield and a competing control stimulus, matched for all relevant physical features, in the other. In Experiment 1, the inducers used to construct the Kanizsa and control stimuli flickered at unique frequencies (10 and 13.33 Hz) to elicit SSVEPs. In Experiment 2, segments were removed briefly from static circular placeholders within the left and right visual hemifields to induce ERPs. In both experiments, participants were instructed to attend covertly to the stimulus on the left or right side to detect brief contrast changes of the inducers. SSVEP analyses revealed that illusory shapes that were ignored yielded a significantly larger neural response than those elicited by non-illusory control stimuli. By contrast, when the stimuli were attended, neural responses to the illusory and control stimuli were statistically indistinguishable. Consistent with these steady-state findings, results of the ERP analyses revealed that evoked responses to illusory shapes emerged earlier relative to control stimuli when they were ignored than when they were attended. Taken together the findings suggest that neural activity associated with modal completion is reliably modulated by spatial attention. Specifically, we show that neural responses to actively ignored illusory shapes are elicited earlier and are sustained at a higher amplitude than responses to control stimuli. This advantage for ignored shapes might reflect adaptive signalling of the presence of an object available for future goal-directed behaviour.


Assuntos
Atenção/fisiologia , Ilusões/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Visuais , Feminino , Humanos , Masculino , Campos Visuais , Adulto Jovem
12.
Nucleic Acids Res ; 31(2): 596-601, 2003 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-12527767

RESUMO

The U3271C mutation affecting the human mitochondrial transfer RNA(Leu(UUR)) (hs mt tRNA) is correlated with diabetes and mitochondrial encephalopathies. We have explored the relationship between the structural effects of this mutation and its impact on function using chemical probing experiments and in vitro aminoacylation assays to investigate a series of tRNA constructs. Chemical probing experiments indicate that the U3271C substitution, which replaces an AU pair with a CA mispair, significantly destabilizes the anticodon stem. The introduction of a compensatory A3261G mutation reintroduces base pairing at this site and restores the structure of this domain. In fact, the anticodon stem of the A3261G/U3271C mutant appears more structured than wild-type (WT) hs mt tRNA(Leu(UUR)), indicating that the entirely AU stem of the native tRNA is intrinsically weak. The results of the chemical probing experiments are mirrored in the aminoacylation activities of the mutants. The U3271C substitution decreases aminoacylation reactivity relative to the WT tRNA due to an increase in K(m) for the pathogenic mutant. The binding defect is a direct result of the structural disruption caused by the pathogenic mutation, as the introduction of the stabilizing compensatory mutation restores aminoacylation activity. Other examples of functional defects associated with the disruption of weak domains in hs mt tRNAs have been reported, indicating that the effects of pathogenic mutations may be amplified by the fragile structures that are characteristic of this class of tRNAs.


Assuntos
Anticódon/genética , DNA Mitocondrial/genética , RNA de Transferência de Leucina/genética , Anticódon/química , Sequência de Bases , Eletroforese em Gel de Poliacrilamida , Humanos , Cinética , Leucina-tRNA Ligase/metabolismo , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Mutação Puntual , Aminoacil-RNA de Transferência/metabolismo , RNA de Transferência de Leucina/química , RNA de Transferência de Leucina/metabolismo , Homologia de Sequência do Ácido Nucleico
13.
Org Lett ; 7(1): 99-102, 2005 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-15624987

RESUMO

Peptide conjugates of the xanthene dye rose bengal (RB) are described featuring sequences that promote DNA binding. The complexation of these conjugates with DNA causes efficient quenching of the fluorophore singlet state and suppresses singlet oxygen production. When incubated with human cells, the RB conjugates pass through the cell membrane but are not visualized in the nucleus. This behavior is in stark contrast to that exhibited by structurally analogous conjugates containing the unhalogenated xanthene dye fluorescein. These results highlight the marked sensitivity of cell permeability characteristics to subtle structural differences.


Assuntos
DNA/metabolismo , Peptídeos/síntese química , Rosa Bengala/química , Sequência de Aminoácidos , Produtos do Gene tat/química , Peptídeos/química , Peptídeos/metabolismo , Análise Espectral
15.
RNA ; 11(3): 254-60, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15701731

RESUMO

The A3243G mutation within the human mitochondrial (hs mt) tRNALeuUUR gene is associated with maternally inherited deafness and diabetes (MIDD) and other mitochondrial encephalopathies. One of the most pronounced structural effects of this mutation is the disruption of the native structure through stabilization of a high-affinity dimeric complex. We conducted a series of studies that address the structural properties of this tRNA dimer, and we assessed its formation under physiological conditions. Enzymatic probing was used to directly define the dimeric interface for the complex, and a discrete region of the D-stem and loop of hs mt tRNALeuUUR was identified. The dependence of dimerization on magnesium ions and temperature was also tested. The formation of the tRNA dimer is influenced by temperature, with dimerization becoming more efficient at physiological temperature. Complexation of the mutant tRNA is also affected by the amount of magnesium present, and occurs at concentrations present intracellularly. Terbium probing experiments revealed a specific metal ion-binding site localized at the site of the A3243G mutation that is unique to the dimer structure. This metal ion-binding site presents a striking parallel to dimeric complexes of viral RNAs, which use the same hexanucleotide sequence for complexation and feature a similarly positioned metal ion-binding site within the dimeric structure. Taken together, these results indicate that the unique dimeric complex formed by the hs mt tRNALeuUUR A3243G mutant exhibits interesting similarities to biological RNA dimers, and may play a role in the loss of function caused by this mutation in vivo.


Assuntos
RNA de Transferência de Leucina/química , Sequência de Bases , Dimerização , Eletroforese em Gel de Poliacrilamida , Humanos , Magnésio/química , Sondas Moleculares , Conformação de Ácido Nucleico , Temperatura , Térbio/química
16.
Nat Struct Biol ; 9(8): 586-90, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12101407

RESUMO

Mutations of human mitochondrial transfer RNA (tRNA) are implicated in a variety of multisystemic diseases. The most prevalent pathogenic mitochondrial mutation is the A3243G substitution within the gene for tRNA(Leu(UUR)). Here we describe the pronounced structural change promoted by this mutation. The A3243G mutation induces the formation of a tRNA dimer that strongly self-associates under physiological conditions. The dimerization interface in the mutant tRNA is a self-complementary hexanucleotide in the D-stem, a particularly weak structural element within tRNA(Leu(UUR)). Aminoacylation of the A3243G mutant is significantly attenuated, and mutational studies indicate that dimerization is partially responsible for the observed loss of function. The disruption of a conserved tertiary structural contact also contributes to the functional defect. The pathogenic mutation is proposed to interfere with the cellular function of human mitochondrial tRNA(Leu(UUR)) by destabilizing the native structure and facilitating the formation of a dimeric complex with low biological activity.


Assuntos
RNA de Transferência de Leucina/química , RNA de Transferência de Leucina/genética , RNA/química , RNA/genética , Sequência de Bases , Dimerização , Humanos , Técnicas In Vitro , Dados de Sequência Molecular , Mutação , Conformação de Ácido Nucleico , RNA Mitocondrial
17.
Biochemistry ; 43(2): 384-92, 2004 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-14717592

RESUMO

The structure of the human mitochondrial (hs mt) tRNALeu(UUR) features several domains that are predicted to exhibit limited thermodynamic stability. An elevated frequency of disease-related mutations within these domains suggests a link between structural instability and the functional effects of pathogenic mutations. A series of tRNAs featuring mutations within the D and anticodon stems were prepared and investigated using nuclease probing. Structural mapping studies indicated that these domains were partially denatured for the wild type (WT) hs mt tRNALeu(UUR) and were significantly stabilized by mutations introducing additional or stronger base pairs into the stem regions. In addition, trends in the aminoacylation activities of the D stem mutants suggested that the loose structure is required for function, with mutants displaying the most ordered structures exhibiting the lowest levels of aminoacylation activity. A pronounced interdependence of the structures of the anticodon and D stems was observed, with mutations strengthening the D stem stabilizing the anticodon stem and vice versa. The existence of strong interdomain communication was further elucidated with a mutant of hs mt tRNALeu(UUR) containing a stabilized D stem and a pathogenic mutation that disrupted the anticodon stem. Strengthening the structure of the D stem completely restored the function of the disease-related mutant to WT levels, indicating that propagated structural weaknesses contribute to the functional deactivation of this tRNA by mutations.


Assuntos
Doenças Mitocondriais/genética , Conformação de Ácido Nucleico , RNA de Transferência de Leucina/química , RNA/química , Acilação , Anticódon/química , Anticódon/genética , Anticódon/metabolismo , Sequência de Bases , Humanos , Leucina-tRNA Ligase/química , Leucina-tRNA Ligase/metabolismo , Doenças Mitocondriais/metabolismo , Dados de Sequência Molecular , Desnaturação de Ácido Nucleico , Mutação Puntual , RNA/genética , RNA/metabolismo , RNA Mitocondrial , RNA de Transferência de Leucina/genética , RNA de Transferência de Leucina/metabolismo , Endonucleases Específicas para DNA e RNA de Cadeia Simples/química , Soluções
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