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INTRODUCTION: Oral Health Therapists (OHTs) are a growing workforce globally, with skills in oral health prevention, treatment planning and management of disease. These professionals receive their training through a three-year undergraduate program which leads to the Bachelor of Oral Health degree in Australia and New Zealand. The aim of this study was to describe the learning environment for OHT students in Australia and New Zealand. OHT students were requested to complete the Dundee Ready Education Environment Measure (DREEM) to indicate their perceptions of the environment of their educational program. MATERIALS AND METHODS: Bachelor of Oral Health students from 10 universities in Australia and New Zealand were invited to participate in the survey. The analysis of the students' experiences focused on five domains of educational environment: learning, teaching, academic self-perception, atmosphere and social self-perception. Total DREEM scores were compared to previously published literature for other health professions students. RESULTS: A total of 336 OHT students completed the study, which represented 30% of all OHT students enrolled in the 10 participating universities. Using the DREEM, participants perception of the environment was more positive than negative with an average DREEM total score of 141 (70.5%) out of a maximum score of 200. The model demonstrates university region to be a major predictor in the overall DREEM score, with regional universities scoring higher than urban universities (p = .012). CONCLUSIONS: The DREEM was used to describe OHT students perceptions of the learning environment in Australia and New Zealand. This study found that the university region is a significant predictor of positive experiences for OHT students. By identifying the strengths and weaknesses of contemporary Oral Health programs, this study offers insights into future improvements.
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Aprendizagem , Nova Zelândia , Humanos , Austrália , Feminino , Masculino , Saúde Bucal/educação , Adulto Jovem , Inquéritos e Questionários , Autoimagem , AdultoRESUMO
INTRODUCTION: Dentistry is known to be a challenging degree and students are often under considerable academic pressure which may lead to stress and difficulties in coping. Personality influences coping ability, yet very little is known about the personality traits of dentistry students. This study aimed to describe the personality profiles of students enrolled in an Australian undergraduate dental degree. METHODS: Students enrolled in year one and two of the undergraduate dental programme at The University of Queensland were invited to complete an online survey which included the Temperament and Character Inventory (TCI). Personality was measured by four dimensions of temperament: Novelty Seeking, Harm Avoidance, Reward Dependence and Persistence; and three-character traits: Self-Directedness, Cooperativeness and Self-Transcendence. Data analysis was mostly descriptive, and t tests and univariate statistics compared groups. RESULTS: Participants (n = 134; 97% response rate; females = 51%) were generally single, spoke another language at home and lived in shared accommodation. The majority (55%) were 20-29 years old, and 40% were international students. The sample had average levels of all TCI traits, except for Cooperativeness which was high. CONCLUSIONS: This sample of dentistry students portrayed a profile of temperament and character similar to profiles of other health profession students with the intellectual ability and drives to undertake a competitive and challenging degree. Longitudinal studies are needed to track changes in personality throughout the degree. This would provide insight into how and when to best support students.
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Adaptação Psicológica , Personalidade , Estudantes de Odontologia/psicologia , Adulto , Austrália , Feminino , Humanos , Masculino , Temperamento , Adulto JovemRESUMO
The wrong acknowledgement and funding information were provided in the original publication.
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Written tests for selection into medicine have demonstrated reliability and there is accumulating evidence regarding their validity, but we know little about the broader impacts or consequences of medical school selection tests from the perspectives of key stakeholders. In this first Australian study of its kind, we use consequential validity as a theoretical lens to examine how medical school students and applicants view and experience the Graduate Medical Schools Admission Test (GAMSAT), and the consequences of testing. Participants (n = 447) were recruited from five graduate-entry medical schools across Australia and a publicly available online test preparation forum. An online survey was used to gather demographic information, and quantitative and qualitative data. Quantitative data were analysed via descriptive statistics and qualitative data were thematically analysed. The findings showed there was a considerable financial burden associated with preparing for and sitting the GAMSAT and moderate agreement regarding the GAMSAT as a fair selection method. The main unintended consequences of using the GAMSAT as a selection tool included barriers related to test affordability and language, and socialisation into the hidden curriculum of medicine. Selection tools such as the GAMSAT have some limitations when the goals are to support equitable participation in medicine and professional identity development. Our study highlights the value interpretive and theoretically-informed research in contributing to the evidence base on medical school selection.
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Teste de Admissão Acadêmica/estatística & dados numéricos , Faculdades de Medicina/organização & administração , Estudantes de Medicina/psicologia , Adulto , Austrália , Estudos Transversais , Feminino , Humanos , Idioma , Masculino , Estudos Prospectivos , Reprodutibilidade dos Testes , Critérios de Admissão Escolar , Faculdades de Medicina/economia , Faculdades de Medicina/normas , Adulto JovemRESUMO
Clinician-scientists are a valuable resource and are crucial to ensuring that high-quality health and medical research is undertaken and translated to patients. Although the literature notes the global decline in clinician-scientists and infers the worldwide similarity in the challenges to reverse this decline, Australia continues to lag behind in establishing an infrastructure to address the dilemma.
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Pesquisa Biomédica/educação , Escolha da Profissão , Mobilidade Ocupacional , Estudantes de Medicina , Austrália , Certificação , Educação Médica , Humanos , Recursos HumanosRESUMO
The Queensland branch of the Royal Australasian College of Physicians (RACP) commissioned this study to update their workforce profile and examine rural practice. The present investigation aimed to describe characteristics of Queensland physicians and determine the influence of childhood and training locations on current rural practice. A cross-sectional online survey, conducted 4 July-4 November 2013, was administered to Fellows of The RACP, Queensland. Descriptive statistics report characteristics and logistic regression analyses identify associations and interactions. The outcome measure was current practice location using the Australian Standard Geographic Classification - Remoteness Area. Data were obtained for 633 physicians. Their average age was 49.5 years, a third was female and a quarter was in rural practice. Rural practice was associated with a rural childhood (odds ratio (OR) (95% confidence interval, CI) 1.89 (1.10, 3.27) P = 0.02) and any time spent as an intern (OR 4.07 (2.12, 7.82) P < 0.001) or registrar (OR 4.00 (2.21, 7.26) P < 0.001) in a rural location. Physicians with a rural childhood and rural training were most likely to be in rural practice. However, those who had a metropolitan childhood and a rural internship were approximately five times more likely to be working in rural practice than physicians with no rural exposure (OR 5.33 (1.61, 17.60) P < 0.01). The findings demonstrate the positive effect of rural vocational training on rural practice. A prospective study would determine if recent changes to the Basic Physician Training Pathway and the Basic Paediatric Training Network (more rural training than previous pathways) increases the rate of rural practice.
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Escolha da Profissão , Internato e Residência , Médicos/estatística & dados numéricos , Serviços de Saúde Rural , Adulto , Estudos Transversais , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Queensland , Recursos HumanosRESUMO
BACKGROUND: Personality traits refer to habitual patterns of behaviour, thought and emotions, and have been shown to influence health professionals' career decisions, career development, job satisfaction and retention. There is an opportunity to better understand and support the career pathways of dietitians by exploring their personality traits. The two primary aspects of personality are: (i) temperament traits, which determine automatic emotional responses to experiences, and are generally stable over lifetime, and (ii) character traits, which reflect personal goals and values, and tend to develop with life experience. The present study explored the levels of temperament and character traits of dietitians, as well as their relationship to demographic variables. METHODS: The study comprised a cross-sectional online survey of 346 Australian dietitians [95% female; mean (SD) age 32 (10) years; mean (SD) time since graduation 7 (9) years]. Temperament and character traits were measured by the Temperament and Character Inventory. Key demographic variables were measured to describe career decisions and pathways of dietitians. Multivariate analyses of variance was used to investigate the relationship between demographic variables and personality traits. RESULTS: Levels of several traits were significantly associated with gender, age and highest level of education. In comparison to the general population, the dietitians displayed average levels of Novelty Seeking; high levels of Harm Avoidance, Reward Dependence, Persistence, Self-Directedness and Cooperativeness; and low levels of Self-Transcendence. CONCLUSIONS: The dietitians in the present study displayed levels of personality traits that were similar to other health professionals, although they differed from the general population. These findings are the precursor to further work that may inform recruitment strategies and career counselling in dietetics.
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Nutricionistas , Personalidade , Adulto , Idoso , Austrália , Escolha da Profissão , Caráter , Estudos Transversais , Dietética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inventário de Personalidade , Temperamento , Adulto JovemRESUMO
INTRODUCTION: Recruitment and retention of allied health professionals (AHPs) to remote and rural Australia is challenging and correlates with poorer health status of remote and rural residents. While much has been written about the recruitment and retention problem, this study took a new approach by reviewing the literature describing the motivation of AHPs to work in remote and rural areas and then analyzing the findings from the perspective of motivation theory using Herzberg's extrinsic and intrinsic classification. Intrinsic motivation incentives are known to contribute to job satisfaction and come from within the individual, for example the pleasure derived from autonomy or challenge at work. In contrast, extrinsic motivation incentives are provided by the job and include such factors as salary and professional development provisions. Extrinsic incentives are important because they prevent job dissatisfaction. Job satisfaction has been shown to be linked with increased retention. METHOD: Thirty-five articles, including 26 from Australia, met the inclusion criteria. The key findings related to motivation from each article are outlined and the results classified into the extrinsic-intrinsic framework. The incentives are then further analyzed as having a positive or a negative influence. RESULTS: In total, 38 different incentives were described a total of 246 times. Of the total, almost half (n=115) comprised extrinsic incentives with a negative influence, with poor access to professional development, professional isolation and insufficient supervision the most frequently reported. Rural lifestyle and diverse caseloads were the most frequently mentioned positive extrinsic incentives, while autonomy and community connectedness were the most cited positive intrinsic incentives. Negative intrinsic incentives were mentioned least frequently (n=18); however, of these, feeling overwhelmed and that your work was not valued by the community were the most commonly reported. CONCLUSIONS: The results demonstrate the significant burden of extrinsic incentives with a negative influence that are perceived by AHPs in remote and rural areas. The high turnover rate of AHPs in remote and rural areas is likely to be, in part, due to the job dissatisfaction from these disincentives. More positive intrinsic incentives were reported than negative. This suggests the potential for intrinsic incentives, known to contribute to job satisfaction, to be mediating the extrinsic disincentives. The policy implications of this work include the importance of addressing extrinsic disincentives. Simultaneously, the existing intrinsic incentives need to be nurtured and developed. Organizations that implement strategies to enhance both extrinsic and intrinsic motivation incentives are more likely to successfully address their AHP workforce shortage.
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Pessoal Técnico de Saúde , Motivação , Lealdade ao Trabalho , Seleção de Pessoal , Serviços de Saúde Rural , Pessoal Técnico de Saúde/psicologia , Humanos , Grupos Populacionais , População Rural , Terminologia como Assunto , População Urbana , Recursos HumanosRESUMO
INTRODUCTION: The intern year is a critical time for making career decisions and gaining confidence in clinical skills, communication and teamwork practices; this justifies an interest in junior doctors' perceptions of their level of preparedness for hospital work. This study explored Australian junior doctors' perspectives regarding the transition from student to doctor roles, their preparation as medical undergraduates within either traditional metropolitan schools or smaller, outer metropolitan-based (rural) programs such as Rural Clinical Schools (RCS), and the educational environment they experienced in their internship. METHODS: A qualitative cross-sectional design used semi-structured interviews with postgraduate year one and two junior doctors (9 females and 11 males) within teaching hospitals in Queensland Australia. Interview questions focussed on four major content areas: preparedness for hospital work, undergraduate training, building confidence and career advice. Data were analyzed using a framework method to identify and explore major themes. RESULTS: Junior doctors who spent undergraduate years training at smaller, non-traditional medical schools felt more confident and better prepared at internship. More hands-on experience as students, more patient contact and a better grounding in basic sciences were felt by interns to be ideal for building confidence. Junior doctors perceived a general lack of career guidance in both undergraduate and postgraduate teaching environments to help them with the transition from the student to junior doctor roles. DISCUSSION: Findings are congruent with studies that have confirmed student opinion on the higher quality of undergraduate medical training outside a traditional metropolitan-based program, such as a RCS. The serious shortage of doctors in rural and remote Australia makes these findings particularly relevant. It will be important to gain a better understanding of how smaller non-traditional medical programs build confidence and feelings of work readiness in graduates. Career advice should become a more regular part of the medical education continuum.
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Escolha da Profissão , Competência Clínica , Internato e Residência/estatística & dados numéricos , Percepção , População Rural/estatística & dados numéricos , Faculdades de Medicina/estatística & dados numéricos , Adulto , Atitude do Pessoal de Saúde , Estudos Transversais , Coleta de Dados , Educação de Pós-Graduação em Medicina , Educação de Graduação em Medicina , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Corpo Clínico Hospitalar/psicologia , Pesquisa Qualitativa , Queensland , AutoimagemRESUMO
INTRODUCTION: This article provides an in-depth investigation of the accommodation circumstances of a population of aging adults with intellectual disability living at home with parents or in supported accommodation in an Australian regional centre. Given the ageing of both the carer and adult population with intellectual disability our research explored the accommodation needs and perceptions of future lifestyle issues from the perspective of both the carers and the adults with intellectual disability. This study aimed to describe these accommodation circumstances related to a regional/rural location and did not make direct comparisons with urban/metropolitan situations. METHODS: A mixed methods approach, specifically an explanatory design, participant selection model was utilised for the overall study. This article reports on the qualitative study consisting of data from both free response open-ended survey questions and semi-structured interviews with selected adults with intellectual disability and their carers. This study explored and described participants' experiences and perceptions regarding their accommodation needs and future lifestyle issues. A purposive sampling technique was used to identify a representative sample of participants for interviews. The interview questions were guided by the results of the quantitative first study phase. Data were analysed by content analysis for major themes emerging from the interview and free response survey data. RESULTS: A total of 146 carers (mean age 61.5 years; range 40-91 years) and 156 adults with intellectual disability (mean age 37.2 years; range 18-79 years) participated in the study. Data saturation was reached after 10 interviews were undertaken with carers (mean age 60 years) and 10 with adults with intellectual disability (no age criteria applied). Six major themes were identified: ageing, family issues, living at home, living away from home, government support and funding, and future needs. The perceptions and views of both adults with intellectual disability and their carers around these major themes are reported and discussed. CONCLUSIONS: This study indicates that there is a lack of suitable, available, supported accommodation for people aged 18 years and older with intellectual disability in this Australian regional centre. Consequently, aging parents caring at home have little choice but to continue in their caring role. For those caring away from home, existing services are decreasingly seen as fitting the ideal life they want for the person with intellectual disability for whom they care. The told experiences, perceptions and views of older carers of and adults with intellectual disability have highlighted their increasing vulnerability to the 'disability system'. The findings suggest that government and disability services must acknowledge the changing needs of people with intellectual disability in connection with their advancing age and the urgency of increasing care needs due to the advancing age of their carer's. The overwhelming feeling is that the carer's voice will only be heard when the situation reaches crisis point. For many carers and their families this has already occurred.
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Cuidadores , Necessidades e Demandas de Serviços de Saúde , Habitação , Deficiência Intelectual , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Austrália , Feminino , Humanos , Entrevistas como Assunto , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
INTRODUCTION: The Australian Rural Clinical Schools, established nationally in 2000-2001, have provided an opportunity for medical students to undertake their clinical training across a network of hospitals, general practice surgeries and community medical centres in locations throughout Australia. The Rural Clinical School at the University of Queensland was established in 2002, as the Rural Clinical Division (RCD) of the School of Medicine, which provides a four-year graduate MB BS program. Students may elect to train in their 3rd and/or 4th year in one of three clinical divisions, namely Central, Southern (both based in Brisbane) or Rural which comprises teaching sites in south west Queensland and central Queensland region. Training must be of an equivalent nature throughout these three divisions, because students all sit the same examinations. Rigorous evaluation of the RCD teaching program underpins the goals of continuing improvement of both education and resources, and is also a key component of the reporting mechanisms linked to ongoing Commonwealth funding. Students' perception of their medical education at the RCD is the major focus of such evaluations in order to assist both educational improvement and required student recruitment. With this in mind, a questionnaire, the 'Year 4 Exit Survey' was developed to evaluate medical student perceptions of their 4th year experience at the RCD. Coupled to this was an analysis of internship choices to evaluate the important related issue of medical graduate retention. OBJECTIVE: The increasing popularity of the RCD has prompted further investigation into the intern placement choice by these students. The provision of a positive medical education experience in a Rural Clinical School might be expected to influence this intern choice to favour a rural location. This preliminary report provides the results of the evaluations by one cohort of year 4 students and explores the relationship between rural undergraduate medical training experiences and subsequent recruitment and retention of junior medical personnel within local rural hospitals. METHODS: The Year 4 Exit Survey contained 63 questions and was a combination of open-ended and forced answer items. The survey was divided into the following sections: demographics, career interests, experience of rural living, interest in rural medical practice, perceptions of rural communities, perceptions of the RCD, rating of their medical training, the impact of the RCD on their desire to practice medicine in a rural area, their opinions on the most and least valuable study experiences at either site and their suggestions on how that experience might be improved. A final question asked them their choice of internship location and the reasons why they were or were not staying at their present RCD site. RESULTS: Overall there was a high degree of student satisfaction with all aspects of their medical education. However there was a discrepancy between these findings and subsequent internship choices. Reasons for this discrepancy were associated with the students' adverse perceptions of their future workforce environment and professional support. CONCLUSIONS: Provision of positive rural training experiences and quality medical education has been shown to increase interest in rural medicine and encourage a desire to pursue a medical career in a rural area. However a quality undergraduate rural medical education does not guarantee immediate transition to rural internship. If the ultimate goal of improving the rural medical workforce is to be achieved, the present high levels of recruitment by the Rural Clinical Schools and their provision of a positive rural training experience must be matched by a supportive clinical workplace environment. Studies are needed to look more closely at the transition period between medical graduate and intern.
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Escolha da Profissão , Educação de Graduação em Medicina/organização & administração , Internato e Residência/organização & administração , Seleção de Pessoal/organização & administração , Serviços de Saúde Rural , Estudantes de Medicina/psicologia , Adulto , Atitude do Pessoal de Saúde , Competência Clínica , Feminino , Hospitais Rurais , Humanos , Satisfação no Emprego , Estudos Longitudinais , Masculino , Avaliação das Necessidades , Reorganização de Recursos Humanos/estatística & dados numéricos , Área de Atuação Profissional , Avaliação de Programas e Projetos de Saúde , Queensland , Inquéritos e Questionários , Recursos HumanosRESUMO
A modification of the tissue printing technique was used to acutely isolate and culture cells from the electrosensory lateral line lobe (ELL), corpus cerebelli (CCb), and eminentia granularis pars posterior (EGp) of the adult weakly electric fish, Apteronotus leptorhynchus. Cells were isolated without the use of proteolytic enzymes and tissue printed as a monolayer onto glass coverslips through centrifugation in the presence of a medium designed to preserve cell structure. Tissue printed cells were reliably distributed in an organotypic fashion that allowed for the identification of anatomical boundaries between the ELL and cerebellar regions, distinct sensory maps in the ELL, and specific cell laminae. Many cells were isolated with an excellent preservation of soma-dendritic structure, permitting direct identification of all electrosensory cell classes according to morphological or immunocytochemical criteria. Several classes of glial cells were isolated, including small diameter microglia and the complex arborizations of oligodendrocytes. A plexus of fine processes were often isolated in conjunction with cell somata and dendrites, potentially preserving synaptic contacts in vitro. In particular, immunolabel for gamma-aminobutyric acid (GABA) revealed a previously unrecognized network of GABAergic axonal processes in the CCb and EGp granule cell body and molecular layers. Tissue printed cells were readily maintained with an organotypic distribution of glial and neuronal elements for up to 27 days in culture. This procedure will allow for the isolation of electrosensory cells from adult central nervous system for electrophysiological analyses of membrane properties or synaptic interactions between identified cells.
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Cerebelo/fisiologia , Peixe Elétrico/fisiologia , Neurônios Aferentes/fisiologia , Animais , Células Cultivadas , Cerebelo/citologia , Eletrofisiologia , Imuno-Histoquímica , Bulbo/citologia , Bulbo/crescimento & desenvolvimento , Bulbo/fisiologia , Células Piramidais/fisiologia , Sinapses/fisiologiaRESUMO
The amount of water bound to disodium cromoglycate (DSCG) in frozen aqueous solutions was determined from the amplitude of the n.m.r. free induction decay. The hydration number was found to be 15 molecules H2O/molecule DSCG of which 6 H2O molecules were less strongly bound than the rest. Proton T1 and T2 relaxation times in non-frozen solutions implied a values of 10(-8) s for the correlation time of the bound water at 291 K. This is consistent with the mobility of DSCG molecules in a smectic mesophase.
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Cromolina Sódica , Água/análise , Fenômenos Químicos , Química , Congelamento , Espectroscopia de Ressonância Magnética , Soluções/análiseRESUMO
BACKGROUND: Obese parturients are recognised as high risk and an antenatal anaesthetic consultation is recommended. The potential positive and negative effects of this consultation have not been investigated. This prospective observational study aimed to determine if antenatal anaesthetic consultation affects decisional conflict, anxiety scores or risk perception in obese women planning vaginal delivery. METHODS: Eligible women had a body mass index of > or = 35 kg/m2, planning a vaginal delivery, aged > or = 18 years and able to complete a questionnaire presented in English. Before their anaesthetic consultation, women completed a written decisional conflict questionnaire, the Six-Point Short Form of the Speilberger State-Trait Anxiety Inventory and two questions regarding risk perception. All questions were repeated by telephone consultation two weeks later. Independent samples t-tests were used to detect differences between pre and post-test scores. RESULTS: Of 114 women recruited, 89 completed the protocol and were analysed. Women had a mean ±SD age of 29.4±5.2 years and body mass index of 43.6±5.6 kg/m2. Decisional conflict scores were significantly lower after the consultation (30.04 vs. 16.54, P<0.001). Anxiety scores were lower (9.41 vs. 8.49, P=0.002) but this was not clinically significant. Only 19.1% of women felt their health was at risk in pregnancy; this did not change after the consultation. Thirteen women changed their preference toward epidural analgesia (P=0.01). DISCUSSION: Our results support the current practice of referral of obese parturients for anaesthetic consultation, but demonstrate that most women remain unaware of the risks of obesity in pregnancy despite anaesthetic consultation.
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Anestesia Obstétrica/métodos , Anestesia Obstétrica/psicologia , Ansiedade/psicologia , Obesidade/complicações , Encaminhamento e Consulta , Adulto , Ansiedade/etiologia , Ansiedade/prevenção & controle , Tomada de Decisões , Feminino , Humanos , Obesidade Mórbida/complicações , Gravidez , Complicações na Gravidez , Cuidado Pré-Natal , Estudos Prospectivos , Medição de RiscoAssuntos
DNA , Condutividade Elétrica , RNA , Álcalis , Fenômenos Biofísicos , Biofísica , Carboidratos , Escuridão , Transferência de Energia , Luz , Nucleosídeos , Nucleotídeos , Polímeros , Purinas , Semicondutores , TemperaturaRESUMO
Charge carrier generation and transport in the mitochondrial lipoprotein system has been investigated by electrical conductivity, low frequency dielectric relaxation, and thermoelectric power. A parallel study was conducted on morphological/structural changes by DTA and NMR. The results obtained confirm the need to consider concurrently free charge carrier processes and polarization phenomena. All techniques show a "transition" at the same temperature. The steady state conductivity is correlated with main chain segmental reorientations of the phospholipid moiety below the transition and with an interfacial polarization process above it. The Seebeck coefficient provides a useful new aid to characterizing the charge carriers, confirming that they are electronic. The terminal cytochrome oxidase component was investigated separately but it largely reflected ionic impurities characteristic of the isolation process, so that the results were of no intrinsic value.
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Lipoproteínas/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteínas Mitocondriais/metabolismo , Animais , Bovinos , Análise Diferencial Térmica , Condutividade Elétrica , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Miocárdio/citologia , Miocárdio/metabolismo , Ressonância Magnética Nuclear Biomolecular , TemperaturaRESUMO
A colloidal dispersion of chloranil in water or an aqueous solution of an amino acid shows an ESR signal characteristic of the semiquinone radical anion. The signal is broadened in the presence of bovine plasma albumin, and the available evidence supports the idea that the freedom of the free radical is restricted by a weak association with a specific site in the protein.
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Cloranila , Quinonas , Soroalbumina Bovina , Aminoácidos , Animais , Bovinos , Fenômenos Químicos , Química , Cloranila/análogos & derivados , Coloides , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres , Soluções , ÁguaRESUMO
Hypochlorous acid (HOCl) is a toxic oxidant produced by neutrophils at sites of cardiac inflammation. To examine the effect of this oxidant on Ca2+ homeostasis in the heart, isolated rabbit ventricular myocytes were iontophoretically loaded with the Ca2+ indicator fura 2 and superfused with 100 microM HOCl under voltage-clamp conditions. Ca2+ transients and the corresponding Ca2+ currents were elicited by 300-msec depolarizing pulses from -40 to 0 mV. Within 200 seconds after HOCl addition, the amplitude of the Ca2+ transients was reduced from 402 +/- 89 to 82 +/- 29 nM (p less than 0.01) while intracellular free ([Ca2+]i increased from 78 +/- 16 to 265 +/- 48 nM (p less than 0.01). During this time, the amplitude of the slow inward currents increased by 10%, while steady-state holding current remained stable. This sustained steady-state rise in [Ca2+]i occurred even in the absence of extracellular Ca2+ but was virtually abolished by a 20-second preexposure to 10 mM caffeine, suggesting that the major source of this Ca2+ was the sarcoplasmic reticulum. Although washout of HOCl failed to induce recovery, subsequent exposure to the dithiol reducing agent dithiothreitol caused a rapid restoration of both the steady-state [Ca2+]i and Ca2+ transient amplitude. We conclude that 1) HOCl caused a rise of [Ca2+]i by inducing the release of Ca2+ from internal stores and impairing cellular extrusion mechanisms and 2) these effects occur through alteration of protein thiol redox status.
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Cálcio/metabolismo , Ditiotreitol/farmacologia , Homeostase/efeitos dos fármacos , Ácido Hipocloroso/farmacologia , Miocárdio/metabolismo , Animais , Eletroquímica , Miocárdio/citologia , Concentração Osmolar , CoelhosRESUMO
Reperfusion injury in ischemic myocardium is caused partially by polymorphonuclear leukocyte oxygen free radicals, the most toxic of which may be hypochlorous acid (HOCl). This study shows that dithiothreitol (DTT), a disulfide-reducing agent, can restore contractile function to cardiac muscles that had been exposed to physiological levels of HOCl. Isometrically contracting isolated rat papillary muscles which were exposed to HOCl (300 microM) showed a rapid and essentially complete loss of developed force, an increase in resting force, and a sharp decline in myocyte protein sulfhydryls (PSH). The addition of DTT (1 mM) after 40 min resulted in a significant (40%) restoration of contractile function. Earlier addition of DTT effected a more complete functional recovery. The DTT-induced recovery was accompanied by a matching increase in cellular PSH levels, suggesting that HOCl injury may be caused primarily by the oxidation of cysteine residues. These data suggest that DTT may prove to be useful in reversing oxidant injury in tissues exposed to oxygen free radicals.