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1.
BMJ Open Qual ; 9(4)2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33028655

RESUMO

INTRODUCTION: Over 40 000 CT scans are performed in our emergency department (ED) annually and utilisation is over 80% capacity. Improving medical appropriateness of CT scans may reduce total number of scans, time, cost and radiation exposure. METHODS: Lean Six Sigma methodology was used to improve the process. A National Emergency X-Radiography Utilisation Study (NEXUS)-based PowerForm was implemented in the electronic health record and providers were educated on the criteria. RESULTS: The rate of potentially medically inappropriate CT C-spine scans decreased from 45% (19/42) to 22% (90/403) (two-proportion test, p=0.002). After the intervention, there was no longer a difference between midlevel providers and physicians in the rate of medically inappropriate orders (19% vs 22%) (two-proportion test, p=0.850) compared with that before the intervention (56% vs 31%) (two-proportion test, p<0.01). Overall rates of CT C-spine scans ordered decreased from 69.3 to 62.6/week (t-test, p=0.019). CONCLUSION: A validated clinical decision-making tool implemented into the medical record can improve quality of care. This study lays a foundation for other imaging studies with validated support tools with similar potential improvements.


Assuntos
Vértebras Cervicais/diagnóstico por imagem , Serviço Hospitalar de Emergência/estatística & dados numéricos , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Tomografia Computadorizada por Raios X/métodos , Vértebras Cervicais/lesões , Serviço Hospitalar de Emergência/organização & administração , Serviço Hospitalar de Emergência/normas , Humanos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/normas , Tomografia Computadorizada por Raios X/estatística & dados numéricos , Gestão da Qualidade Total
2.
BMJ Open Qual ; 9(2)2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32434794

RESUMO

Unintended omission of warfarin, an anticoagulant used to prevent and treat thromboembolic events, can lead to serious medical complications. These complications include increased medical costs, hospitalisations and significant patient harm, including increased risk of thrombosis and mortality. Chart review of discharged patients at our institution revealed an average of one patient/month with warfarin omitted from the discharge plan despite intention to continue therapy. Lean Six Sigma methodology was used to improve the process. A system alert was implemented in the electronic health record to alert providers of patients who received warfarin during admission, the discharge medication reconciliation was complete, and there was no prescription for warfarin. Date and time of last warfarin dose and international normalised ratio were included in the alert. Providers had the option to return to the chart to update the discharge medication plan and add the warfarin prescription or to choose an appropriate over-ride reason. The number of patients discharged without an intended warfarin prescription following alert implementation was reduced from 10.5% (4/38) to 0% (0/40) (two proportion test, p=0.03). Alert tracking enhanced the ability to identify patients at risk for warfarin omissions. Process sustainability has been achieved by embedding system alerts in the electronic health record to trigger process steps.


Assuntos
Erros Médicos/prevenção & controle , Alta do Paciente/normas , Gestão da Qualidade Total/métodos , Varfarina/administração & dosagem , Anticoagulantes/administração & dosagem , Anticoagulantes/uso terapêutico , Humanos , Erros Médicos/estatística & dados numéricos , Alta do Paciente/estatística & dados numéricos , Varfarina/uso terapêutico
3.
BMJ Open Qual ; 9(1)2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31986120

RESUMO

INTRODUCTION: Lack of medication conversion from intravenous to oral contributes to increased risk of infection, delayed discharges and higher medication costs. At our institution, intravenous to oral medication conversion rate was 76% with missed opportunity for conversion of 37%. The goal of the project was to reduce the percent of missed opportunities for intravenous to oral conversion for applicable medications. METHODS: A pharmacy-driven intravenous to oral policy and procedure was implemented. To identify potential opportunities, a patient worklist of applicable intravenous to oral medications was created for pharmacy review in real time. An intravenous to oral conversion order was implemented in the computerised provider order entry. 'Convert to oral' was added as an option in the electronic medication request and highlighted reminders were added to the electronic medication administration record for eligible medications. RESULTS: After improvements, the missed opportunity rate for intravenous to oral conversion decreased from 37% (19/51) to 21% (24/113) (p=0.04, two-proportion test), a 43% improvement. The trend in intravenous to oral conversion rate increased from 76% (39/51) to 85% (171/201) and severity adjusted length of stay was reduced from 8.1 days to 6.4 days post improvements (p<0.001, t-test).


Assuntos
Administração Intravenosa , Administração Oral , Sistemas de Registro de Ordens Médicas , Assistência Farmacêutica , Melhoria de Qualidade , Gestão da Qualidade Total , Humanos , Preparações Farmacêuticas/economia
5.
BMJ Open Qual ; 7(4): e000101, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30397656

RESUMO

Patients with diabetes require access to systematic and ongoing care delivered by a team of healthcare providers. Despite national attention and well-accepted best practices, diabetic care, blood pressure and haemoglobin A1c (A1c) levels for patients with diabetes in our primary care setting were highly variable and below the Healthcare Effectiveness Data and Information Set (HEDIS) 75th percentile benchmark. From January 2015 to January 2016, 22% of patients with diabetes in our primary care setting had both blood pressure and A1c levels controlled and 23% had their annual diabetic care bundle completed, which includes A1c and blood pressure measurements, foot examination and nephropathy attention. Lack of standardised care algorithms, electronic health record documentation and education was identified. Lean Six Sigma methodologies were used to re-engineer the care that patients with diabetes receive. Key improvement initiatives focused on standardisation of accepted care practices through electronic templates, education and re-evaluation of patients to make 90-day, rapid cycle changes. Interventions were piloted in one primary care clinic then expanded to eight additional clinics. At the pilot site, the per cent of patients who completed the diabetic care bundle increased from 33% to 71% and the per cent of patients with diabetes with both A1c and blood pressure controlled increased from 31% to 43% (two-proportion test, p<0.01) postintervention. On rollout to eight additional clinics, the per cent of patients who completed the diabetic care bundle increased from 23% to 67% and the per cent of patients with diabetes with both their A1c and their blood pressure controlled increased from 22% to 41% (two-proportion test, p<0.01). After the interventions, nephropathy attention, A1c and blood pressure metrics exceeded HEDIS 75th percentile. Standardisation of accepted care practices for patients with diabetes improved compliance with diabetic care bundle completion and patient outcomes in the primary care setting.

6.
BMJ Open Qual ; 7(3): e000279, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30057955

RESUMO

Treatment recommendations for submassive pulmonary embolus (SMPE), defined as pulmonary embolus (PE) resulting in right ventricular dysfunction and/or myocardial necrosis, vary. The objective of this study was to develop an investigative protocol at our tertiary care hospital to standardise the approach to patients with SMPE and to evaluate the effect of the protocol on process measures including consultation with cardiology and critical care physicians and time to echocardiogram and treatment. Triggered by right ventricle/left ventricle ratios >0.9, the protocol standardised ancillary studies and immediate consultation with critical care and cardiology. Post-protocol implementation, the percent of patients with SMPE evaluated by critical care specialists increased from 26% (19/74) to 93% (41/44) (p<0.001) and cardiology consultations increased from 35% (26/74) to 89% (39/44) (p<0.001). Patient arrival to echocardiogram was reduced from 15 hours to 5 hours post-protocol implementation. In addition, average time to anticoagulation was reduced from greater than 7 hours to 3 hours 27 min post-protocol implementation. The protocol has helped to identify patients with SMPE and standardise the care they receive after diagnosis.

7.
BMJ Open Qual ; 7(2): e000239, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30019010

RESUMO

Delirium is a key quality metric identified by The Society of Critical Care Medicine for intensive care unit (ICU) patients. If not recognised early, delirium can lead to increased length of stay, hospital and societal costs, ventilator days and risk of mortality. Clinical practice guidelines recommend ICU patients be assessed for delirium at least once per shift. An initial audit at our urban tertiary care hospital in Illinois, USA determined that delirium assessments were only being performed 31% of the time. Nurses completed simulation based education and were trained using delirium screening videos. After the educational sessions, delirium documentation increased from 40% (12/30) to 69% (41/59) (two-proportion test, p<0.01) for dayshift nurses and from 27% (8/30) to 61% (36/59) (two-proportion test, p<0.01) during the nightshift. To further increase the frequency of delirium assessments, the delirium screening tool was standardised and a critical care progress note was implemented that included a section on delirium status, management strategy and discussion on rounds. After the documentation changes were implemented, delirium screening during dayshift increased to 93% (75/81) (two-proportion test, p<0.01). Prior to this project, physicians were not required to document delirium screening. After the standardised critical care note was implemented, documentation by physicians was 95% (106/111). Standardising delirium documentation, communication of delirium status on rounds, in addition to education, improved delirium screening compliance for ICU patients.

8.
BMJ Open Qual ; 7(2): e000296, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30019011

RESUMO

Acute myocardial infarction (AMI) follow-up care is a crucial part of the AMI recovery process. The American College of Cardiology's 'See You in 7 Challenge' advocates that all patients discharged with a diagnosis of AMI have a cardiac rehabilitation referral made and outpatient cardiac rehabilitation appointment scheduled to occur within 7 days of hospital discharge. A streamlined AMI cardiac rehabilitation referral and appointment scheduling process was not in place at this urban academic medical centre. To develop the streamlined processes, a Six Sigma project was initiated. Four months before the intervention, 1/38 patients with AMI (2.6%) were scheduled to have the initial outpatient cardiac rehabilitation appointment occur within 7 days of hospital discharge, with an average 18.7 days from hospital discharge to the scheduled initial outpatient cardiac rehabilitation appointment. To reduce the time to this initial appointment, availability of outpatient cardiac rehabilitation appointments was increased, additional staff were trained in appointment scheduling and insurance verification processes and appointments were scheduled prior to hospital discharge. After intervention, the number of patients scheduled to attend an outpatient cardiac rehabilitation appointment within 7 days of hospital discharge improved to 72/79 (91.1%) (two-proportion test, p<0.001). Days from hospital discharge to first scheduled outpatient cardiac rehabilitation appointment were reduced from 18.7 days to 6.3 days (a 66.3% reduction) (Mann-Whitney U test, p<0.01). Initial outpatient cardiac rehabilitation attendance within 7 days of hospital discharge increased from 1/38 (2.6%) to 42/79 (53.2%) (a 50.6% increase) (two-proportion test, p<0.001).

9.
Am J Emerg Med ; 36(9): 1635-1639, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29937274

RESUMO

INTRODUCTION: Emergency Department (ED) physicians' next day discharge rate (NDDR), the percentage of patients who were admitted from the ED and subsequently discharged within the next calendar day was hypothesized as a potential measure for unnecessary admissions. The objective was to determine if NDDR has validity as a measure for quality of individual ED physician performance. METHODS: Hospital admission data was obtained for thirty-six ED physicians for calendar year 2015. Funnel plots were used to identify NDDR outliers beyond 95% control limits. A mixed model logistic regression was built to investigate factors contributing to NDDR. To determine yearly variation, data from calendar years 2014 and 2016 were analyzed, again by funnel plots and logistic regression. Intraclass correlation coefficient was used to estimate the percent of total variation in NDDR attributable to individual ED physicians. RESULTS: NDDR varied significantly among ED physicians. Individual ED physician outliers in NDDR varied year to year. Individual ED physician contribution to NDDR variation was minimal, accounting for 1%. Years of experience in Emergency Medicine practice was not correlated with NDDR. CONCLUSION: NDDR does not appear to be a reliable independent quality measure for individual ED physician performance. The percent of variance attributable to the ED physician was 1%.


Assuntos
Médicos/normas , Indicadores de Qualidade em Assistência à Saúde , Idoso , Competência Clínica/normas , Competência Clínica/estatística & dados numéricos , Medicina de Emergência/normas , Medicina de Emergência/estatística & dados numéricos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Humanos , Tempo de Internação/estatística & dados numéricos , Modelos Logísticos , Masculino , Médicos/estatística & dados numéricos , Indicadores de Qualidade em Assistência à Saúde/estatística & dados numéricos
10.
BMJ Open Qual ; 7(2): e000281, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29713690

RESUMO

Medication reconciliation is an important component to the care of hospitalised patients and their safe transition to the ambulatory setting. In our Family Medicine Hospitalist Service, patient care is frequently transferred between the various physicians, residents, nurses and eventually to a separate group of providers who provide ambulatory management. Due to frequent transitions of care, there was no clear ownership of the medication reconciliation process. To improve the medication reconciliation process, a Transition of Care Team composed of registered nurses was created to oversee the entire reconciliation process. The team engaged the patient and their family, when needed, contacted patients' pharmacies and their providers, reconciled the patients' hospital medication list with the ambulatory list at hospital admission and within 24 hours of discharge, and attended the hospital follow-up visit to verify medications and provide continuity of care. Implementation of the team allowed for additional investigative resources, redundancy in preventing errors and early recovery should an error occur. The percent of medications with error after implementation of the Transition of Care Team was reduced from 131/386 (33.9%) to 147/787 (18.7%) at hospital admission, 81/354 (22.9%) to 42/834 (5.0%) at discharge and 43/337 (12.8%) to 6/809 (0.7%) at follow-up visit (two proportion tests, p<0.001). In addition, the percent of charts without any errors improved at hospital discharge from 8/31 (25.8%) to 46/70 (65.7%) and at hospital follow-up visit from 16/31 (51.6%) to 64/70 (91.4%) (two-proportion test, p<0.001). Previously viewed as three separate reconciliations occurring at admission, discharge and hospital follow-up, the approach to medication reconciliation was reframed as a continuous process occurring throughout the hospitalisation and hospital follow-up resulting in improved reconciliation accuracy and safer transitions to the ambulatory setting.

11.
J Innov Health Inform ; 24(3): 907, 2017 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-29121848

RESUMO

BACKGROUND: Amylase and lipase, pancreatic biomarkers, are measured in acute pancreatitis diagnosis. Since amylase testing does not add diagnostic value, lipase testing alone is recommended. Despite new recommendations, many physicians and staff continue to test both amylase and lipase. OBJECTIVE: To reduce unnecessary diagnostic testing in acute pancreatitis. METHODS: The pre-checked amylase test within the Emergency Department's Computerized Provider Order Entry (CPOE) abdominal pain order set was changed to an un-checked state, but kept as an option to order with a single click. Amylase testing, lipase testing and cost were measured for one year pre and post intervention. RESULTS: Simple de-selection intervention reduced redundant amylase testing from 71% to 9%, resulting in a percent of decrease of 87% and an annualized saving of approximately $719,000 in charges. CONCLUSION: CPOE de-selection is an effective tool to reduce non-value added activity and reduce cost while maintaining quality patient care and physician choice.


Assuntos
Amilases/economia , Redução de Custos , Serviço Hospitalar de Emergência , Sistemas de Registro de Ordens Médicas , Médicos , Melhoria de Qualidade , Doença Aguda , Amilases/análise , Testes Diagnósticos de Rotina , Humanos , Pancreatite/diagnóstico
12.
Artigo em Inglês | MEDLINE | ID: mdl-28469912

RESUMO

Patient safety event reporting is an important component for fostering a culture of safety. Our tertiary care hospital utilizes a computerized patient safety event reporting system that has been historically underutilized by residents and faculty, despite encouragement of its use. The objective of this quality project was to increase patient safety event reporting within our Emergency Medicine residency program. Knowledge of event reporting was evaluated with a survey. Eighteen residents and five faculty participated in a formal educational session on event reporting followed by feedback every two months on events reported and actions taken. The educational session included description of which events to report and the logistics of accessing the reporting system. Participants received a survey after the educational intervention to assess resident familiarity and comfort with using the system. The total number of events reported was obtained before and after the educational session. After the educational session, residents reported being more confident in knowing what to report as a patient safety event, knowing how to report events, how to access the reporting tool, and how to enter a patient safety event. In the 14 months preceding the educational session, an average of 0.4 events were reported per month from the residency. In the nine months following the educational session, an average of 3.7 events were reported per month by the residency. In addition, the reported events resulted in meaningful actions taken by the hospital to improve patient safety, which were shared with the residents. Improvement efforts including an educational session, feedback to the residency of events reported, and communication of improvements resulting from reported events successfully increased the frequency of safety event reporting in an Emergency Medicine residency.

13.
West J Emerg Med ; 18(3): 479-486, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28435500

RESUMO

INTRODUCTION: Pediatric obesity threatens the efficacy of medications given intramuscularly. In anaphylactic patients, epinephrine auto-injector needle lengths are potentially too short to reach the muscle compartment in patients with elevated body habitus. The objective of the study was to determine needle-length requirements for intramuscular injections in pediatric patients. METHODS: We used ultrasound to measure the distance from skin to muscle compartment of the thigh in 200 pediatric patients of various weight and body mass index who presented to the emergency department. RESULTS: Patients with higher body mass index had an increased distance to muscle and bone. If current recommendations were followed, 5% of patients within the EpiPen adult weight category and 11% of patients within the Centers for Disease Control and Prevention weight category would have potentially used a needle inadequate in length for intramuscular injections. CONCLUSION: With the increase in childhood obesity, needle lengths may be too short to effectively deliver medications to the intramuscular compartment. Needle length should be evaluated to accommodate pediatric patients with increased skin to muscle distance.


Assuntos
Anafilaxia/tratamento farmacológico , Epinefrina/administração & dosagem , Antagonistas dos Receptores Histamínicos H1/administração & dosagem , Injeções Intramusculares/instrumentação , Músculo Esquelético/diagnóstico por imagem , Obesidade Infantil/complicações , Coxa da Perna/diagnóstico por imagem , Adolescente , Índice de Massa Corporal , Criança , Pré-Escolar , Desenho de Equipamento/efeitos adversos , Falha de Equipamento , Feminino , Humanos , Lactente , Injeções Intramusculares/efeitos adversos , Masculino , Músculo Esquelético/anatomia & histologia , Agulhas/efeitos adversos , Valor Preditivo dos Testes , Estudos Prospectivos , Coxa da Perna/anatomia & histologia , Ultrassonografia , Estados Unidos
14.
J Biol Rhythms ; 32(2): 109-120, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28347186

RESUMO

PAS domain-containing proteins can act as environmental sensors that capture external stimuli to allow coordination of organismal physiology with the outside world. These proteins permit diverse ligand binding and heterodimeric partnership, allowing for varied combinations of PAS-dependent protein-protein interactions and promoting crosstalk among signaling pathways. Previous studies report crosstalk between circadian clock proteins and the aryl hydrocarbon receptor (AhR). Activated AhR forms a heterodimer with the circadian clock protein Bmal1 and thereby functionally inhibits CLOCK/Bmal1 activity. If physiological activation of AhR through naturally occurring, endogenous ligands inhibits clock function, it seems plausible to hypothesize that decreased AhR expression releases AhR-induced inhibition of circadian rhythms. Because both AhR and the clock are important regulators of glucose metabolism, it follows that decreased AhR will also alter metabolic function. To test this hypothesis, rhythms of behavior, metabolic outputs, and circadian and metabolic gene expression were measured in AhR-deficient mice. Genetic depletion of AhR enhanced behavioral responses to changes in the light-dark cycle, increased rhythmic amplitude of circadian clock genes in the liver, and altered rhythms of glucose and insulin. This study provides evidence of AhR-induced inhibition that influences circadian rhythm amplitude.


Assuntos
Ritmo Circadiano , Periodicidade , Receptores de Hidrocarboneto Arílico/deficiência , Receptores de Hidrocarboneto Arílico/genética , Transdução de Sinais , Fatores de Transcrição ARNTL/genética , Fatores de Transcrição ARNTL/metabolismo , Animais , Relógios Circadianos , Expressão Gênica , Glucose/metabolismo , Camundongos , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Fotoperíodo , Receptores de Hidrocarboneto Arílico/metabolismo
15.
Chronobiol Int ; 34(3): 318-336, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28102700

RESUMO

High fat diet (HFD) consumption alters the synchronized circadian timing system resulting in harmful loss, gain or shift of transcriptional oscillations. The aryl hydrocarbon receptor (AhR) shares structural homology to clock genes, containing both PAS domains and basic helix-loop helix structural motifs, allowing for interaction with components of the primary circadian feedback loop. Activation of AhR alters circadian rhythmicity, primarily through inhibition of Clock/Bmal1-mediated regulation of Per1. AhR-deficient mice are protected from diet-induced metabolic dysfunction, exhibiting enhanced insulin sensitivity and glucose tolerance. This study examined whether AhR haploinsufficiency can also protect against diet-induced alterations in rhythm. After feeding AhR+/+ and AhR+/- mice an HFD (60% fat) for 15 weeks, samples were collected every 4 hours over a 24-hour period. HFD altered the rhythm of serum glucose and the metabolic transcriptome, including hepatic nuclear receptors Rev-erbα and PPARγ in wild-type c57bl6/j mice. AhR reduction provided protection against diet-induced transcriptional oscillation changes; serum glucose and metabolic gene rhythms were protected from the disruption caused by HFD feeding. These data highlight the critical role of AhR signaling in the regulation of metabolism and provide a potential therapeutic target for diseases characterized by rhythmic desynchrony.


Assuntos
Ritmo Circadiano/fisiologia , Fígado/metabolismo , Receptores de Hidrocarboneto Arílico/deficiência , Fatores de Transcrição ARNTL/genética , Animais , Relógios Circadianos/fisiologia , Dieta Hiperlipídica , Masculino , Camundongos Transgênicos , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo
17.
Environ Health Insights ; 10: 133-41, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27559298

RESUMO

The prevalence of metabolic syndrome, a clustering of three or more risk factors that include abdominal obesity, increased blood pressure, and high levels of glucose, triglycerides, and high-density lipoproteins, has reached dangerous and costly levels worldwide. Increases in morbidity and mortality result from a combination of factors that promote altered glucose metabolism, insulin resistance, and metabolic dysfunction. Although diet and exercise are commonly touted as important determinants in the development of metabolic dysfunction, other environmental factors, including circadian clock disruption and activation of the aryl hydrocarbon receptor (AhR) by dietary or other environmental sources, must also be considered. AhR binds a range of ligands, which prompts protein-protein interactions with other Per-Arnt-Sim (PAS)-domain-containing proteins and subsequent transcriptional activity. This review focuses on the reciprocal crosstalk between the activated AhR and the molecular circadian clock. AhR exhibits a rhythmic expression and time-dependent sensitivity to activation by AhR agonists. Conversely, AhR activation influences the amplitude and phase of expression of circadian clock genes, hormones, and the behavioral responses of the clock system to changes in environmental illumination. Both the clock and AhR status and activation play significant and underappreciated roles in metabolic homeostasis. This review highlights the state of knowledge regarding how AhR may act together with the circadian clock to influence energy metabolism. Understanding the variety of AhR-dependent mechanisms, including its interactions with the circadian timing system that promote metabolic dysfunction, reveals new targets of interest for maintenance of healthy metabolism.

19.
Int J Obes (Lond) ; 39(8): 1300-1309, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25907315

RESUMO

BACKGROUND/OBJECTIVES: Epidemics of obesity and diabetes are escalating. High-calorie/high-fat food is a major cause for these global health issues, but molecular mechanisms underlying high-fat, diet-induced obesity are still not well understood. The aryl hydrocarbon receptor (AhR), a transcription factor that acts as a xenobiotic sensor, mediates environmental toxicant-induced obesity, insulin resistance and development of diabetes. AhR also influences lipid metabolism and diet-induced obesity. The effects of AhR deficiency on diet-induced obesity, hepatic steatosis and insulin resistance were examined. METHODS: Male wild-type (WT), AhR null (AhR(-/-)) and AhR heterozygote (AhR(+/-)) mice were fed a normal chow diet (NCD, 10% kcal from fat) or a high-fat diet (HFD, 60% kcal from fat) for up to 14 weeks. Adiposity, adipose and liver morphology, insulin signaling, metabolic parameters and gene profiles were assessed. RESULTS: AhR deficiency protected against HFD-induced obesity, hepatic steatosis, insulin resistance and inflammation. Moreover, AhR deficiency preserved insulin signaling in major metabolic tissues. These protective effects result from a higher energy expenditure in AhR-deficient mice compared with WT. Levels of transcript for both the thermogenic gene, uncoupling protein 1 (Ucp1), in brown adipose tissue and mitochondrial ß-oxidation genes in muscle were significantly higher in AhR(-/-) and AhR(+/-) mice compared with WT. CONCLUSIONS: This work documents a physiologically relevant function for AhR in regulation of body weight, hepatic fat deposition, insulin sensitivity and energy expenditure under HFD exposure, suggesting that AhR signaling may be developed as a potential therapeutic target for treatment of obesity and metabolic disorders.


Assuntos
Tecido Adiposo/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/deficiência , Obesidade/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Dieta Hiperlipídica , Modelos Animais de Doenças , Metabolismo Energético , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Insulina/metabolismo , Resistência à Insulina , Metabolismo dos Lipídeos , Masculino , Camundongos , Receptores de Hidrocarboneto Arílico/deficiência , Transdução de Sinais
20.
Toxicol Lett ; 201(2): 116-22, 2011 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-21182907

RESUMO

Activation of the aryl hydrocarbon receptor (AhR) by the highly toxic, prototypical ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or other dioxin-like compounds compromises ovarian function by altering follicle maturation and steroid synthesis. Although alteration of transcription after nuclear translocation and heterodimerization of AhR with its binding partner, aryl hydrocarbon nuclear transporter (ARNT), is often cited as a primary mechanism for mediating the toxic effects of dioxins, recent evidence indicates that crosstalk between AhR and several other signaling pathways also occurs. Like the circadian clock genes, AhR is a member of the basic helix-loop-helix, Per-ARNT-SIM (bHLH-PAS) domain family of proteins. Thus, these studies tested the hypothesis that TCDD can act to alter circadian clock regulation in the ovary. Adult female c57bl6/J mice entrained to a typical 12h light/12h dark cycle were exposed to a single 1 µg/kg dose of TCDD by gavage. Six days after exposure, animals were released into constant darkness and ovaries were collected every 4h over a 24h period. Quantitative real-time PCR and immunoblot analysis demonstrated that TCDD exposure alters expression of the canonical clock genes, Bmal1 and Per2 in the ovary. AhR transcript and protein, which displayed a circadian pattern of expression in the ovaries of control mice, were also altered after TCDD treatment. Immunohistochemistry studies revealed co-localization of AhR with BMAL1 in various ovarian cell types. Furthermore, co-immunoprecipitation demonstrated time-of-day dependent interactions of AhR with BMAL1 that were enhanced after TCDD treatment. Collectively these studies suggest that crosstalk between classical AhR signaling and the molecular circadian clockworks may be responsible for altered ovarian function after TCDD exposure.


Assuntos
Relógios Circadianos/efeitos dos fármacos , Ovário/efeitos dos fármacos , Dibenzodioxinas Policloradas/toxicidade , Fatores de Transcrição ARNTL/análise , Fatores de Transcrição ARNTL/genética , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Ovário/metabolismo , Proteínas Circadianas Period/análise , Proteínas Circadianas Period/genética , Receptores de Hidrocarboneto Arílico/genética
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