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1.
Ir J Psychol Med ; 40(3): 361-368, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-33890559

RESUMO

OBJECTIVE: This study aims to describe the course of admission and clinical characteristics of admissions to a psychiatric intensive care unit (PICU) in the Phoenix Care Centre (PCC), Dublin, Ireland. METHODS: This retrospective chart study was conducted at the PCC, Dublin, Ireland. The cohort included all admission episodes (n = 91 complete data) over a three-year study period between January 2014 and January 2017. RESULTS: The mean age of admitted cases was 37.1 (s.d. = 11.3; range 18-63). The mean length of stay (LOS) was 59.3 days (s.d. = 61.0; median 39.5 days). All patients were admitted under Mental Health Act legislation. Antipsychotic polypharmacy was used in 61% (n = 55) of the admissions. A diagnosis of acute psychotic disorder (B = -1.027, p = 0.003, 95% CI: -1.691, -0.363) was associated with reduced LOS in PICU. CONCLUSION: Our study describes the cohort of patients admitted as being predominantly male, younger-aged, single, having a diagnosis of schizophrenia and being legally detained. The primary indication for referral is risk of assault, which highlights the need for the intensive and secure treatment model that a PICU can provide.


Assuntos
Unidades de Terapia Intensiva Pediátrica , Criança , Humanos , Masculino , Idoso , Feminino , Estudos Retrospectivos , Seguimentos , Irlanda/epidemiologia , Tempo de Internação
2.
Front Psychol ; 13: 837558, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35432055

RESUMO

The current study investigated the adaptations which occur in visual search behaviour as a function of expertise in rugby union players when completing attacking scenarios. Ten experienced players (EP) and ten novice players (NP) completed 2 vs. 1 attacking game scenarios. Starting with the ball in hand and wearing a mobile eye tracker throughout, participants were required to score a try against a defender. The scenarios allowed for a pass to their supporting player (Spin Pass or Switch) or trying to run past the defender (Take-Player-On or Dummy Switch). No between group differences were found in fixating on the supporting attacking player (p > 0.05). However, EP increased the length (p = 0.008) and frequency (p = 0.004) looking at the area immediately ahead of the supporting player, particularly when executing a spin pass. NP fixated longer (p = 0.005) and more frequently (p = 0.032) at the defender, whilst EP fixated more frequently in the space the supporting player would run into in Switch and Dummy Switch scenarios (p = 0.025). More successful passes were completed and tries scored by EP compared to NP (p = 0.001). Differences in visual search behaviour between experienced and NP suggest that the experts extract information from areas directly related to guiding the motor action; the space immediately ahead of the support player to pass the ball in. Contrastingly, novices use a more allocentric perspective where the actions from the defender are used to guide their motor actions.

3.
Ir J Psychol Med ; 38(4): 278-287, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-32912355

RESUMO

Vitamin D deficiency is associated with an increased risk of acute respiratory infection. There is an excess of respiratory infections and deaths in schizophrenia, a condition where vitamin D deficiency is especially prevalent. This potentially offers a modifiable risk factor to reduce the risk for and the severity of respiratory infection in people with schizophrenia, although there is as yet no evidence regarding the risk of COVID-19. In this narrative review, we describe the prevalence of vitamin D deficiency in schizophrenia, report the research examining the relationship between vitamin D levels and COVID-19 and discuss the associations between vitamin D deficiency and respiratory infection, including its immunomodulatory mechanism of action.


Assuntos
COVID-19 , Esquizofrenia , Deficiência de Vitamina D , Humanos , SARS-CoV-2 , Esquizofrenia/epidemiologia , Vitamina D , Deficiência de Vitamina D/complicações , Deficiência de Vitamina D/epidemiologia
4.
Br Med Bull ; 135(1): 73-89, 2020 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-32885238

RESUMO

BACKGROUND: Clozapine remains the only medication licensed for treating refractory schizophrenia. However, it remains underutilized in part due to concerns regarding adverse events. SOURCES OF DATA: Published literature. AREAS OF AGREEMENT: Common adverse events during clozapine treatment include sedation, hypersalivation, postural hypotension, dysphagia, gastrointestinal hypomotility, weight gain, diabetes mellitus and dyslipidaemia. Rare but serious events include agranulocytosis, cardiomyopathy, myocarditis, pneumonia, paralytic ileus and seizure. AREAS OF CONTROVERSY: It remains unclear how best to minimize clozapine-induced morbidity/mortality (i) during dose titration, (ii) from hypersalivation and (iii) from gastrointestinal hypomotility. It is also unclear how clozapine pharmacokinetics are affected by (i) gastrointestinal hypomotility, (ii) systemic infection and (iii) passive exposure to cigarette smoke. Whether monthly haematological monitoring needs to continue after 12 months of uninterrupted therapy is also a subject of debate. GROWING POINTS: There is a need for better management of serious clozapine-related adverse events in addition to agranulocytosis. There is also a need for better education of patients and carers, general practitioners, A&E and ITU staff and others of the problems posed in using clozapine safely. AREAS TIMELY FOR DEVELOPING RESEARCH: There is a need for more research on assessing clozapine dosage (i) as patients get older, (ii) with respect to exposure to cigarette smoke and (iii) optimizing response if adverse events or other factors limit dosage.


Assuntos
Agranulocitose , Antipsicóticos , Clozapina , Esquizofrenia , Agranulocitose/tratamento farmacológico , Antipsicóticos/efeitos adversos , Clozapina/efeitos adversos , Atenção à Saúde , Humanos , Esquizofrenia/tratamento farmacológico
5.
Ir J Psychol Med ; 36(4): 279-291, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-30477599

RESUMO

Recovery rates in schizophrenia remain suboptimal with up to one-third resistant to standard treatments, a population prevalence of 0.2%. Clozapine is the only evidenced-based treatment for treatment resistant schizophrenia (TRS), yet there are significant delays in its use or it may not be trialled, potentially impacting the chance of recovery. Better outcomes with earlier use of clozapine may be possible. There is emerging evidence that early treatment resistance is not uncommon from the earliest stages of psychosis. In this review, we provide an update on TRS, its epidemiology and its management, with a specific focus on the optimal use and timing of clozapine and augmentation strategies for the one-third of patients who do not respond to clozapine.


Assuntos
Antipsicóticos/uso terapêutico , Clozapina/uso terapêutico , Recuperação da Saúde Mental/tendências , Transtornos Psicóticos/terapia , Esquizofrenia/terapia , Adolescente , Terapia Cognitivo-Comportamental/métodos , Resistência a Medicamentos/fisiologia , Eletroconvulsoterapia/métodos , Feminino , Humanos , Masculino , Administração dos Cuidados ao Paciente/normas , Prevalência , Transtornos Psicóticos/epidemiologia , Esquizofrenia/complicações , Esquizofrenia/epidemiologia , Prevenção Secundária/estatística & dados numéricos , Prevenção Secundária/tendências , Adulto Jovem
6.
Ir J Psychol Med ; 34(2): 117-126, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30115215

RESUMO

OBJECTIVES: To evaluate if n-3 polyunsaturated fatty acids (PUFAs) and lipid levels are associated with episodes of self-harm or depression over a 10-year period. METHODS: We included 40 individuals who self-harmed and 40 controls. Episodes of self-harm and depression were ascertained and levels of depression, impulsivity, suicidal ideation and plasma lipid levels measured at baseline and at 10-year follow-up. RESULTS: Further episode(s) of self-harm occurred in 26% of cases. Omega-3 PUFAs or lipids were not predictive of depressive or self-harm episodes. Baseline eicosapentaenoic acid levels were modestly correlated with suicidal ideation at follow-up and dihomo-γ-linolenic acid and arachidonic acid were modestly correlated with motor impulsivity at follow-up in cases. CONCLUSIONS: Despite significant negative correlations at baseline between plasma lipids, n-3 PUFAs and psychopathology, these levels were not predictive of clinical outcome over a 10-year period. Further research however is required due to the relatively low sample size and the risk of selection bias due to loss to follow-up in this study.

7.
Psychol Med ; 46(15): 3231-3240, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27605254

RESUMO

BACKGROUND: Clozapine remains the only evidence-based antipsychotic for treatment-resistant schizophrenia (TRS). The ability to predict which patients with their first onset of schizophrenia would subsequently meet criteria for treatment resistance (TR) could help to diminish the severe functional disability which may ensue if TR is not recognized and correctly treated. METHOD: This is a 5-year longitudinal assessment of clinical outcomes in a cohort of 246 first-episode schizophrenia spectrum patients recruited as part of the NIHR Genetics and Psychosis (GAP) study conducted in South London from 2005 to 2010. We examined the relationship between baseline demographic and clinical measures and the emergence of TR. TR status was determined from a review of electronic case records. We assessed for associations with early-, and late-onset TR, and non-TR, and differences between those TR patients treated with clozapine and those who were not. RESULTS: Seventy per cent (n = 56) of TR patients, and 23% of the total study population (n = 246) were treatment resistant from illness onset. Those who met criteria for TR during the first 5 years of illness were more likely to have an early age of first contact for psychosis (<20 years) [odds ratio (OR) 2.49, 95% confidence interval (CI) 1.25-4.94] compared to those with non-TR. The relationship between an early age of first contact (<20 years) and TR was significant in patients of Black ethnicity (OR 3.71, 95% CI 1.44-9.56); and patients of male gender (OR 3.13 95% CI 1.35-7.23). CONCLUSIONS: For the majority of the TR group, antipsychotic TR is present from illness onset, necessitating increased consideration for the earlier use of clozapine.


Assuntos
Antipsicóticos/uso terapêutico , Resistência a Medicamentos , Transtornos Psicóticos/tratamento farmacológico , Esquizofrenia/tratamento farmacológico , Adulto , Fatores Etários , População Negra , Clozapina/uso terapêutico , Feminino , Humanos , Londres , Estudos Longitudinais , Masculino , Razão de Chances , Transtornos Psicóticos/psicologia , Fatores de Risco , Psicologia do Esquizofrênico , Fatores Sexuais , População Branca , Adulto Jovem
8.
BMC Psychiatry ; 16: 76, 2016 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-27000113

RESUMO

BACKGROUND: Suboptimal vitamin D levels have been identified in populations with psychotic disorders. We sought to explore the relationship between vitamin D deficiency, clinical characteristics and cardiovascular disease risk factors among people with established psychosis. METHODS: Vitamin D levels were measured in 324 community dwelling individuals in England with established psychotic disorders, along with measures of mental health, cardiovascular risk and lifestyle choices. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25-OHD) levels below 10 ng/ml (equivalent to <25 nmol/L) and "sufficient" Vitamin D as above 30 ng/ml (>50 nmol/L). RESULTS: The mean 25-OHD serum level was 12.4 (SD 7.3) ng/ml, (range 4.0-51.7 ng/ml). Forty nine percent (n = 158) were vitamin D deficient, with only 14 % (n = 45) meeting criteria for sufficiency. Accounting for age, gender, ethnicity and season of sampling, serum 25-OHD levels were negatively correlated with waist circumference (r = -0.220, p < 0.002), triglycerides (r = -0.160, p = 0.024), total cholesterol (r = -0.144, p = 0.043), fasting glucose (r = -0.191, p = 0.007), HbA1c (r = -0.183, p = 0.01), and serum CRP levels (r = -0.211, p = 0.003) and were linked to the presence of metabolic syndrome. CONCLUSIONS: This is the largest cross sectional study of serum 25-OHD levels in community dwelling individuals with established psychosis, indicating a high level of vitamin D deficiency. Lower vitamin D levels are associated with increased cardiovascular disease risk factors and in particular metabolic syndrome. Further research is needed to define appropriate protocols for vitamin D testing and supplementation in practice to see if this can improve cardiovascular disease risk. TRIAL REGISTRATION: ISRCTN number is ISRCTN58667926 Date of registration: 23/04/2010.


Assuntos
Transtornos Psicóticos/sangue , Transtornos Psicóticos/epidemiologia , Deficiência de Vitamina D/sangue , Deficiência de Vitamina D/epidemiologia , Adulto , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/epidemiologia , Colesterol/sangue , Comorbidade , Estudos Transversais , Inglaterra , Feminino , Humanos , Masculino , Síndrome Metabólica/sangue , Síndrome Metabólica/epidemiologia , Prevalência , Fatores de Risco , Triglicerídeos/sangue , Vitamina D/análogos & derivados , Vitamina D/sangue
9.
Occup Med (Lond) ; 66(3): 215-21, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26668247

RESUMO

BACKGROUND: An increasing number of patients in the working population are undergoing total hip and knee replacement for osteoarthritis and the timing and success of return to work (RTW) is becoming increasingly important as a measure of success for these patients. There is limited understanding of the patient variables that determine the ability to RTW. AIMS: To explore the factors influencing RTW following hip and knee replacement from the patient's perspective. METHODS: A cross-sectional population-based postal survey carried out with patients of working age after hip and knee replacement surgery in a UK teaching hospital. Free text comments were collected regarding the experiences of patients returning to work following hip and knee replacement. Qualitative thematic analysis was undertaken to identify the factors influencing RTW from the patient's perspective. RESULTS: From the patients' perspective three key factors were identified that influenced RTW. Patients reported an improved physical and psychological performance at work after surgery in comparison to pre-operative functioning, although there was a lack of informed advice regarding RTW after surgery. Workplace support and adaptation of the job role enhanced the experience of RTW. CONCLUSIONS: Return to work is influenced by a combination of patient, clinician and occupational factors. The relationship between each of these needs to be explored in greater depth through further qualitative work to gain a wider understanding of the variables influencing patients' RTW following hip and knee replacement.


Assuntos
Artroplastia do Joelho , Satisfação do Paciente/estatística & dados numéricos , Retorno ao Trabalho , Local de Trabalho , Artroplastia do Joelho/psicologia , Artroplastia do Joelho/reabilitação , Artroplastia do Joelho/estatística & dados numéricos , Estudos Transversais , Inglaterra/epidemiologia , Feminino , Humanos , Masculino , Saúde Ocupacional , Pesquisa Qualitativa , Recuperação de Função Fisiológica , Retorno ao Trabalho/psicologia , Retorno ao Trabalho/estatística & dados numéricos , Inquéritos e Questionários
10.
Psychol Med ; 45(12): 2631, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26165543

RESUMO

The author regrets to announce that affiliation 8, in the above article (Gardner-Sood et al. 2015), contained an error in the author affiliation address and author surname, which were published in the approved article. The correct surname and affiliation address are given below. J. Eberhard, Clinical Psychiatric Research Center, Lund University, Skåne, Sweden

11.
Psychol Med ; 45(12): 2619-29, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25961431

RESUMO

BACKGROUND: The aims of the study were to determine the prevalence of cardiometabolic risk factors and establish the proportion of people with psychosis meeting criteria for the metabolic syndrome (MetS). The study also aimed to identify the key lifestyle behaviours associated with increased risk of the MetS and to investigate whether the MetS is associated with illness severity and degree of functional impairment. METHOD: Baseline data were collected as part of a large randomized controlled trial (IMPaCT RCT). The study took place within community mental health teams in five Mental Health NHS Trusts in urban and rural locations across England. A total of 450 randomly selected out-patients, aged 18-65 years, with an established psychotic illness were recruited. We ascertained the prevalence rates of cardiometabolic risk factors, illness severity and functional impairment and calculated rates of the MetS, using International Diabetes Federation (IDF) and National Cholesterol Education Program Third Adult Treatment Panel criteria. RESULTS: High rates of cardiometabolic risk factors were found. Nearly all women and most men had waist circumference exceeding the IDF threshold for central obesity. Half the sample was obese (body mass index ≥ 30 kg/m2) and a fifth met the criteria for type 2 diabetes mellitus. Females were more likely to be obese than males (61% v. 42%, p < 0.001). Of the 308 patients with complete laboratory measures, 57% (n = 175) met the IDF criteria for the MetS. CONCLUSIONS: In the UK, the prevalence of cardiometabolic risk factors in individuals with psychotic illnesses is much higher than that observed in national general population studies as well as in most international studies of patients with psychosis.


Assuntos
Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/psicologia , Transtornos Mentais/epidemiologia , Síndrome Metabólica/epidemiologia , Síndrome Metabólica/psicologia , Adolescente , Adulto , Idoso , Benzodiazepinas/efeitos adversos , Benzodiazepinas/uso terapêutico , Doenças Cardiovasculares/etiologia , Centros Comunitários de Saúde Mental , Diabetes Mellitus Tipo 2/epidemiologia , Inglaterra/epidemiologia , Feminino , Humanos , Masculino , Transtornos Mentais/diagnóstico , Transtornos Mentais/tratamento farmacológico , Pessoa de Meia-Idade , Obesidade/epidemiologia , Prevalência , Fatores de Risco , População Rural , Distribuição por Sexo , Medicina Estatal , População Urbana , Adulto Jovem
12.
Ir J Psychol Med ; 32(2): 177-185, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30185241

RESUMO

OBJECTIVES: The system of weekly psychiatric ward rounds is being challenged and multi-disciplinary team meetings (MDTMs) involving inpatients have been developed. These aim to improve integration between medical and social services and increase patient involvement in their care. However, such large meetings are potentially threatening to the patient. This survey aimed to examine inpatient experience of MDTMs and identify factors that significantly alter this experience. METHODS: In this cross-sectional survey we assessed patient opinion regarding patient inclusive MDTMs in a psychiatric inpatient unit. A total of 27 participants (response rate 90%) were included. We utilised descriptive statistics and Fisher's exact test for non-parametric data where appropriate. RESULTS: In all, 85% (n=23) of patients identified the consultant psychiatrist as a member that they would like to have present at the MDTM. The ward nurse was identified by 63% (n=17) of patients. In all, 48% (n=13) of patients reported feeling anxious/threatened at the MDTM. In all, 70% (n=19) of patients stated that they would have felt less threatened at the MDTM if there were fewer people in attendance. A significant number of voluntary patients (n=11) felt threatened/anxious at the MDTM compared with involuntary patients (n=2) (χ 2=4.921, df=1, p=0.026). CONCLUSION: The central findings of this study are that patients would prefer fewer people at the MDTM and would feel less threatened/anxious if they participated in selecting those in attendance. These findings suggest that greater patient involvement in preparation for the MDTM could result in a less anxiety filled experience for them.

13.
Am J Physiol Regul Integr Comp Physiol ; 307(9): R1115-23, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25163918

RESUMO

In skeletal muscle the Rab-GTPase-activating protein TBC1D1 has been implicated in the regulation of fatty acid oxidation by an unknown mechanism. We determined whether TBC1D1 altered fatty acid utilization via changes in protein-mediated fatty acid transport and/or selected enzymes regulating mitochondrial fatty acid oxidation. We also determined the effects of TBC1D1 on glucose transport and oxidation. Electrotransfection of mouse soleus muscles with TBC1D1 cDNA increased TBC1D1 protein after 2 wk (P<0.05), without altering its paralog AS160. TBC1D1 overexpression decreased basal palmitate oxidation (-22%) while blunting 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)-stimulated palmitate oxidation (-18%). There was a tendency to increase fatty acid esterification (+10 nmol·g(-1)·60 min(-1), P=0.07), which reflected the reduction in fatty acid oxidation (-12 nmol·g(-1)·60 min(-1)). Concomitantly, basal (+21%) and AICAR-stimulated glucose oxidation (+8%) were increased in TBC1D1-transfected muscles relative to their respective controls (P<0.05), independent of changes in GLUT4 and glucose transport. The reductions in TBC1D1-mediated fatty acid oxidation could not be attributed to changes in the transporter FAT/CD36, muscle mitochondrial content, CPT1 expression or the expression and phosphorylation of AS160, acetyl-CoA carboxylase, or AMPK. However, TBC1D1 overexpression reduced ß-HAD enzyme activity (-18%, P<0.05). In conclusion, TBC1D1-mediated reduction of muscle fatty acid oxidation appears to occur via inhibition of ß-HAD activity.


Assuntos
3-Hidroxiacil-CoA Desidrogenases/metabolismo , Músculo Esquelético/enzimologia , Proteínas Nucleares/metabolismo , Palmitatos/metabolismo , 3-Hidroxiacil-CoA Desidrogenases/genética , Aminoimidazol Carboxamida/análogos & derivados , Animais , Ácidos Graxos/metabolismo , Proteínas Ativadoras de GTPase , Regulação da Expressão Gênica/fisiologia , Glucose/metabolismo , Peroxidação de Lipídeos , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Nucleares/genética , Oxirredução , Ribonucleotídeos
14.
Ir Med J ; 106(1): 15-7, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23472370

RESUMO

The purpose of this study was to ascertain the prevalence of hypercalcaemia and hyperparathyroidism in individuals on long term lithium therapy who were monitored by their general practitioners and living within the West Galway mental health catchment area. We also wished to assess the extent of screening for calcium dysfunction in this patient cohort.Current guidelines do not specify the need for calcium monitoring in patients on lithium therapy. We conducted a retrospective analysis of clinical and laboratory data collected as part of regular monitoring for patients on long term lithium treatment. Three hundred and thirty three patients had serum lithium levels monitored over a 2 year period. Fifteen patients (5.3%) had lithium associated hypercalcaemia. The mean duration of lithium treatment for those with hypercalcaemia was 15 years and these patients had a mean serum calcium level of 2.7mmol/L. Eighty six (14%) patients did not have a calcium level monitored over the 2 year period. Three patients (1%) were found to have hyperparathyroidism. This survey supports the need for regular monitoring of serum calcium levels in patients on maintenance lithium treatment.


Assuntos
Hipercalcemia/epidemiologia , Hiperparatireoidismo/epidemiologia , Lítio/uso terapêutico , Atenção Primária à Saúde , Feminino , Humanos , Irlanda/epidemiologia , Lítio/sangue , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Retrospectivos
15.
Ir J Psychol Med ; 30(1): 73-76, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30199946

RESUMO

We present the case of a 23-year-old man with a first episode of severe mania, which was refractory to pharmacotherapy. The case demonstrates a rapid response and full recovery after the use of electroconvulsive therapy (ECT). The ECT was administered involuntarily under Section 59(1) (b) of the Irish Mental Health Act 2001 as the patient was unable to consent to the treatment. The case highlights the benefits of ECT for this serious condition and emphasises the importance of retaining the legislative capacity to provide such an effective treatment for patients unable to consent because of severe psychotic illness.

16.
Ir J Psychol Med ; 30(2): 141-149, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30199968

RESUMO

The use of community treatment orders (CTOs) remains controversial despite their widespread use in a number of different countries. The focus of a CTO should be on individuals with severe and enduring mental disorders, typically requiring adherence with recommended outpatient treatment in the community and requiring that they allow access to members of the clinical team for the purpose of assessment. There is no current provision for CTOs under Irish mental health legislation, although patients who are involuntarily detained under the MHA 2001 (Ireland) can be granted approved leave from hospital. This provision allows for the patient to be managed in the community setting, though, while technically on leave, they remain as inpatients detained under the MHA 2001 (Ireland). This article describes the use of CTOs and considerations relating to their implementation. There is discussion of the ethical grounds and evidence base for their use. Ethical considerations such as balancing autonomy against health needs and the utilisation of capacity principles need to be weighed by clinicians considering the use of CTOs. Though qualitative research provides some support for the use of CTOs, there remains a clear lack of robust evidence based findings to support their use in terms of hospitalisation rates, duration of illness remission and improved social functioning.

17.
Acta Physiol (Oxf) ; 205(1): 71-81, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22463611

RESUMO

AIM: The increase in skeletal muscle fatty acid metabolism during exercise has been associated with the release of calcium. We examined whether this increase in fatty acid oxidation was attributable to a calcium-induced translocation of the fatty acid transporter CD36 to the sarcolemma, thereby providing an enhanced influx of fatty acids to increase their oxidation. METHODS: Calcium release was triggered by caffeine (3 mm) to examine fatty acid oxidation in intact soleus muscles of WT and CD36-KO mice, while fatty acid transport and mitochondrial fatty acid oxidation were examined in giant vesicles and isolated mitochondria, respectively, from caffeine-perfused hindlimb muscles of WT and CD36-KO mice. Western blotting was used to examine calcium-induced signalling. RESULTS: In WT, caffeine stimulated muscle palmitate oxidation (+136%), but this was blunted in CD36-KO mice (-70%). Dantrolene inhibited (WT) or abolished (CD36-KO) caffeine-induced palmitate oxidation. In muscle, caffeine-stimulated palmitate oxidation was not attributable to altered mitochondrial palmitate oxidation. Instead, in WT, caffeine increased palmitate transport (+55%) and the translocation of fatty acid transporters CD36, FABPpm, FATP1 and FATP4 (26-70%) to the sarcolemma. In CD36-KO mice, caffeine-stimulated FABPpm, and FATP1 and 4 translocations were normal, but palmitate transport was blunted (-70%), comparable to the reductions in muscle palmitate oxidation. Caffeine did not alter the calcium-/calmodulin-dependent protein kinase II phosphorylation but did increase the phosphorylation of AMPK and acetyl-CoA carboxylase comparably in WT and CD36-KO. CONCLUSION: These studies indicate that sarcolemmal CD36-mediated fatty acid transport is a primary mediator of the calcium-induced increase in muscle fatty acid oxidation.


Assuntos
Antígenos CD36/metabolismo , Cafeína/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Ácido Palmítico/metabolismo , Animais , Antígenos CD36/genética , Cálcio/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias Musculares/efeitos dos fármacos , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Oxirredução/efeitos dos fármacos
18.
Diabetologia ; 55(2): 479-88, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22101973

RESUMO

AIMS/HYPOTHESIS: Little is known about the subcellular distribution of lipids in insulin-resistant skeletal muscle. However, it has recently been suggested that lipid accumulation in the subsarcolemmal region directly contributes to insulin resistance. Therefore we hypothesised that regional differences in lipid distribution in insulin-resistant muscle may be mediated by: (1) a reduction in fatty acid trafficking into mitochondria; and/or (2) a regional increase in the enzymes regulating lipid synthesis. METHODS: Transmission electron microscopy was used to quantify lipid droplet and mitochondrial abundance in the subsarcolemmal and intermyofibrillar compartments in red and white muscles from lean and obese Zucker rats. To estimate rates of lipid trafficking into mitochondria, the metabolic fate of radiolabelled palmitate was determined. Key enzymes of triacylglycerol synthesis were also determined in each subcellular region. RESULTS: Subsarcolemmal-compartmentalised lipids represented a small absolute fraction of the overall lipid content in muscle, as regardless of fibre composition (red/white) or phenotype (lean/obese), lipid droplets were more prevalent in the intermyofibrillar region, whereas insulin-resistant white muscles were devoid of subsarcolemmal-compartmentalised lipid droplets. While, in obese animals, lipid droplets accumulated in both subcellular regions, in red muscle of these animals lipids only appeared to be trafficked away from intermyofibrillar mitochondria, a process that cannot be explained by regional differences in the abundance of triacylglycerol esterification enzymes. CONCLUSIONS/INTERPRETATION: Lipid accumulation in the subsarcolemmal region is not necessary for insulin resistance. In the intermyofibrillar compartment, the diversion of lipids away from mitochondria in insulin-resistant animals probably contributes to lipid accumulation in this subcellular area.


Assuntos
Lipídeos/química , Obesidade/genética , Frações Subcelulares/metabolismo , Animais , DNA Mitocondrial/metabolismo , Modelos Animais de Doenças , Ácidos Graxos/química , Feminino , Glucose/metabolismo , Insulina/metabolismo , Microscopia Eletrônica de Transmissão/métodos , Mitocôndrias/metabolismo , Obesidade/metabolismo , Oxigênio/química , Ácido Palmítico/metabolismo , Ratos , Ratos Zucker , Triglicerídeos/química
19.
Diabetologia ; 54(6): 1457-67, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21442160

RESUMO

AIMS/HYPOTHESIS: We examined in skeletal muscle (1) whether fatty acid transport protein (FATP) 1 channels long-chain fatty acid (LCFA) to specific metabolic fates in rats; and (2) whether FATP1-mediated increases in LCFA uptake exacerbate the development of diet-induced insulin resistance in mice. We also examined whether FATP1 is altered in insulin-resistant obese Zucker rats. METHODS: LCFA uptake, oxidation and triacylglycerol esterification rates were measured in control and Fatp1-transfected soleus muscles to determine FATP1-mediated lipid handling. The effects of FATP1 on insulin sensitivity and triacylglycerol accumulation were determined in high-fat diet-fed wild-type mice and in muscle-specific Fatp1 (also known as Slc27a1) overexpressing transgenic mice driven by the muscle creatine kinase (Mck [also known as Ckm]) promoter. We also examined the relationship between FATP1 and both fatty acid transport and metabolism in insulin-resistant obese Zucker rats. RESULTS: Transient Fatp1 overexpression in soleus muscle increased (p < 0.05) palmitate transport (24%) and oxidation (35%), without altering triacylglycerol esterification or the intrinsic rate of palmitate oxidation in isolated mitochondria. In Mck/Fatp1 animals, Fatp1 mRNA and 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid uptake in skeletal muscle were upregulated (75%). However, insulin sensitivity and intramuscular triacylglycerol content did not differ between wild-type and Mck/Fatp1 mice following a 16 week high-fat diet. In insulin-resistant obese Zucker rats, LCFA transport and triacylglycerol accumulation were increased (85% and 24%, respectively), but this was not attributable to Fatp1 expression, as neither total cellular nor sarcolemmal FATP1 content were altered. CONCLUSIONS/INTERPRETATION: Overexpression of Fatp1 in skeletal muscle increased the rate of LCFA transport and channelled these lipids to oxidation, not to intramuscular lipid accumulation. Therefore, skeletal muscle FATP1 overabundance does not predispose animals to diet-induced insulin resistance.


Assuntos
Gorduras na Dieta/efeitos adversos , Proteínas de Transporte de Ácido Graxo/metabolismo , Ácidos Graxos/metabolismo , Resistência à Insulina/fisiologia , Músculo Esquelético/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Camundongos , Camundongos Transgênicos , Mitocôndrias Musculares/metabolismo , Obesidade/metabolismo , Obesidade/fisiopatologia , Oxirredução , Palmitatos/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Zucker , Triglicerídeos/metabolismo
20.
Diabetologia ; 53(9): 2008-19, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20490453

RESUMO

AIMS/HYPOTHESIS: Reductions in peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1alpha) levels have been associated with the skeletal muscle insulin resistance. However, in vivo, the therapeutic potential of PGC-1alpha has met with failure, as supra-physiological overexpression of PGC-1alpha induced insulin resistance, due to fatty acid translocase (FAT)-mediated lipid accumulation. Based on physiological and metabolic considerations, we hypothesised that a modest increase in PGC-1alpha levels would limit FAT upregulation and improve lipid metabolism and insulin sensitivity, although these effects may differ in lean and insulin-resistant muscle. METHODS: Pgc-1alpha was transfected into lean and obese Zucker rat muscles. Two weeks later we examined mitochondrial biogenesis, intramuscular lipids (triacylglycerol, diacylglycerol, ceramide), GLUT4 and FAT levels, insulin-stimulated glucose transport and signalling protein phosphorylation (thymoma viral proto-oncogene 2 [Akt2], Akt substrate of 160 kDa [AS160]), and fatty acid oxidation in subsarcolemmal and intermyofibrillar mitochondria. RESULTS: Electrotransfection yielded physiologically relevant increases in Pgc-1alpha (also known as Ppargc1a) mRNA and protein ( approximately 25%) in lean and obese muscle. This induced mitochondrial biogenesis, and increased FAT and GLUT4 levels, insulin-stimulated glucose transport, and Akt2 and AS160 phosphorylation in lean and obese animals, while bioactive intramuscular lipids were only reduced in obese muscle. Concurrently, PGC-1alpha increased palmitate oxidation in subsarcolemmal, but not in intermyofibrillar mitochondria, in both groups. In obese compared with lean animals, the PGC-1alpha-induced improvement in insulin-stimulated glucose transport was smaller, but intramuscular lipid reduction was greater. CONCLUSIONS/INTERPRETATIONS: Increases in PGC-1alpha levels, similar to those that can be induced by physiological stimuli, altered intramuscular lipids and improved fatty acid oxidation, insulin signalling and insulin-stimulated glucose transport, albeit to different extents in lean and insulin-resistant muscle. These positive effects are probably attributable to limiting the PGC-1alpha-induced increase in FAT, thereby preventing bioactive lipid accumulation as has occurred in transgenic PGC-1alpha animals.


Assuntos
Glucose/metabolismo , Insulina/farmacologia , Músculo Esquelético/metabolismo , Obesidade/metabolismo , Proteínas de Ligação a RNA/metabolismo , Magreza/metabolismo , Fatores de Transcrição/metabolismo , Animais , Western Blotting , Ácidos Graxos/metabolismo , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Músculo Esquelético/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fosforilação/efeitos dos fármacos , Proto-Oncogene Mas , Proteínas de Ligação a RNA/genética , Ratos , Ratos Zucker , Transdução de Sinais/efeitos dos fármacos , Fatores de Transcrição/genética
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