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1.
BMC Gastroenterol ; 19(1): 30, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30760205

RESUMO

BACKGROUND: Inflammatory Bowel Disease (IBD) with its high incidence and prevalence rates in Canada generates a heavy burden of tests and procedures. The purpose of this study is to gain a better understanding of the transfer of information from physician to patient, as well as the patient understanding and perceptions about the tests and procedures that are ordered to them in the context of IBD diagnosis and monitoring. METHODS: An online questionnaire was completed by 210 IBD patients in Canada. Information on the five most-often used tests or procedures in IBD diagnosis/monitoring was collected. These include: general blood test, colonoscopy, colon biopsy, medical imaging and stool testing. RESULTS: The general blood test is both the most ordered and most refused tool. It is also the one with which patients are the least comfortable, the one that generates the least concern and the one about which physicians provide the least information. The stool test is the test/procedure with which patients are the most comfortable. Procedures raise more concerns among patients and physicians provide more information about why they are needed, their impact and the risks they present. Very little information is provided to patients about the risks of having false positives or negative tests. CONCLUSIONS: This study provides an initial understanding of patient perceptions, the transfer of information from a physician to a patient and a patient's understanding of the tests and procedures that will be required to treat IBD throughout what is a lifelong disease. The present study takes a first step in better understanding the acceptance of the test or procedure by IBD patients, which is essential for them to adhere to the monitoring process.


Assuntos
Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/psicologia , Aceitação pelo Paciente de Cuidados de Saúde , Educação de Pacientes como Assunto , Percepção , Adolescente , Adulto , Canadá/epidemiologia , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Incidência , Doenças Inflamatórias Intestinais/epidemiologia , Doenças Inflamatórias Intestinais/terapia , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Prevalência , Qualidade de Vida , Inquéritos e Questionários , Recusa do Paciente ao Tratamento , Adulto Jovem
2.
J Crohns Colitis ; 2023 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-37976264

RESUMO

BACKGROUND AND AIM: Multiple factors are suggested to place Crohn's disease patients at risk of recurrence after ileocolic resection with conflicting associations. We aimed to identify clinical predictors of recurrence at first (early) and further (late) postoperative colonoscopy. METHODS: Crohn's disease patients undergoing ileocolic resection were prospectively recruited at six North American centers. Clinical data was collected and endoscopic recurrence was defined as Rutgeerts score ≥i2. A multivariable model was fitted to analyze variables independently associated with recurrence. RESULTS: A total of 365 patients undergoing 674 postoperative colonoscopies were included with a median age of 32 years, 189 (51.8%) were male and 37 (10.1%) non-Whites. Postoperatively, 133 (36.4%) used anti-TNF and 30 (8.2%) were smokers. At first colonoscopy, 109 (29.9%) had recurrence. Male gender (OR = 1.95, 95% CI 1.12 - 3.40), non-White ethnicity (OR = 2.48, 95% CI 1.09 - 5.63), longer interval between surgery and colonoscopy (OR = 1.09, 95% CI 1.002 - 1.18), and postoperative smoking (OR = 2.78, 95% CI 1.16 - 6.67) were associated with recurrence, while prophylactic anti-TNF reduced the risk (OR = 0.28, 95% CI 0.14 - 0.55). Postoperative anti-TNF prophylaxis had a protective effect on anti-TNF experienced patients but not on anti-TNF naïve patients. Among patients without recurrence at first colonoscopy, Rutgeerts score i1 was associated with subsequent recurrence (OR = 4.43, 95% CI 1.73 - 11.35). CONCLUSIONS: We identified independent clinical predictors of early and late Crohn's disease postoperative endoscopic recurrence. Clinical factors traditionally used for risk stratification failed to predict recurrence and need to be revised.

3.
J Gastrointestin Liver Dis ; 29(4): 555-559, 2020 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-33331351

RESUMO

BACKGROUND AND AIMS: Anemia is a common complication of inflammatory bowel diseases (IBD), as well as a predictor of poor outcomes. The aim of this study was to determine the prevalence of anemia over time and the management of moderate to severe anemia at a tertiary referral IBD center. METHODS: We retrospectively reviewed the occurrence of anemia at the time of referral or diagnosis and during follow-up at the McGill University Health Centre IBD center. Consecutive patients presenting with an outpatient visit between July and December 2016 and between December 2018 and March 2019 were included. Disease characteristics, biochemistry and medical management, including the need for intravenous iron therapy were recorded. RESULTS: 1,356 Crohn's disease (CD) and 1,293 ulcerative colitis (UC) patients [disease duration: 12 (IQR: 6-22) and 10 (IQR: 5-19) years respectively] were included. The prevalence of moderate to severe anemia at referral/diagnosis (15.4% and 8.5%) and during follow-up (11.1% and 8.1%) were higher in CD than in UC patients. In CD, previous resective surgery, perianal disease and elevated C-reactive protein (CRP) at assessment, while in UC steroid therapy, an elevated CRP and fecal calprotectin at assessment were associated with anemia in a multivariate analysis. Anemia improved by >2g/dL in 56.5% after 4-6 weeks (intravenous iron dose >1000 mg in 87% of patients). CONCLUSION: Anemia occurred frequently in this IBD cohort, at referral to the center and during follow-up, and contributes to the burden of IBD in referral populations. Most patients were assessed for anemia regularly and with accurate anemia workup; however, the targeted management of moderate to severe anemia was suboptimal.


Assuntos
Anemia/epidemiologia , Colite Ulcerativa/epidemiologia , Doença de Crohn/epidemiologia , Anemia/diagnóstico , Anemia/tratamento farmacológico , Colite Ulcerativa/diagnóstico , Doença de Crohn/diagnóstico , Feminino , Óxido de Ferro Sacarado/administração & dosagem , Hematínicos/administração & dosagem , Humanos , Infusões Intravenosas , Masculino , Prevalência , Quebeque/epidemiologia , Estudos Retrospectivos , Índice de Gravidade de Doença , Centros de Atenção Terciária , Fatores de Tempo
4.
World J Gastroenterol ; 26(7): 759-769, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32116423

RESUMO

BACKGROUND: Emergency situations in inflammatory bowel diseases (IBD) put significant burden on both the patient and the healthcare system. AIM: To prospectively measure Quality-of-Care indicators and resource utilization after the implementation of the new rapid access clinic service (RAC) at a tertiary IBD center. METHODS: Patient access, resource utilization and outcome parameters were collected from consecutive patients contacting the RAC between July 2017 and March 2019 in this observational study. For comparing resource utilization and healthcare costs, emergency department (ED) visits of IBD patients with no access to RAC services were evaluated between January 2018 and January 2019. Time to appointment, diagnostic methods, change in medical therapy, unplanned ED visits, hospitalizations and surgical admissions were calculated and compared. RESULTS: 488 patients (Crohn's disease: 68.4%/ulcerative colitis: 31.6%) contacted the RAC with a valid medical reason. Median time to visit with an IBD specialist following the index contact was 2 d. Patients had objective clinical and laboratory assessment (C-reactive protein and fecal calprotectin in 91% and 73%). Fast-track colonoscopy/sigmoidoscopy was performed in 24.6% of the patients, while computed tomography/magnetic resonance imaging in only 8.1%. Medical therapy was changed in 54.4%. ED visits within 30 d following the RAC visit occurred in 8.8% (unplanned ED visit rate: 5.9%). Diagnostic procedures and resource utilization at the ED (n = 135 patients) were substantially different compared to RAC users: Abdominal computed tomography was more frequent (65.7%, P < 0.001), coupled with multiple specialist consults, more frequent hospital admission (P < 0.001), higher steroid initiation (P < 0.001). Average medical cost estimates of diagnostic procedures and services per patient was $403 CAD vs $1885 CAD comparing all RAC and ED visits. CONCLUSION: Implementation of a RAC improved patient care by facilitating easier access to IBD specific medical care, optimized resource utilization and helped avoiding ED visits and subsequent hospitalizations.


Assuntos
Assistência Ambulatorial/estatística & dados numéricos , Utilização de Instalações e Serviços/estatística & dados numéricos , Doenças Inflamatórias Intestinais/terapia , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Indicadores de Qualidade em Assistência à Saúde/estatística & dados numéricos , Adulto , Assistência Ambulatorial/métodos , Assistência Ambulatorial/normas , Colite Ulcerativa/terapia , Colonoscopia/estatística & dados numéricos , Doença de Crohn/terapia , Emergências , Serviço Hospitalar de Emergência/estatística & dados numéricos , Feminino , Implementação de Plano de Saúde , Acessibilidade aos Serviços de Saúde , Hospitalização/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Estudos Prospectivos , Encaminhamento e Consulta/estatística & dados numéricos
5.
Am J Physiol Endocrinol Metab ; 297(2): E462-73, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19509184

RESUMO

Although the atherogenic role of dietary cholesterol has been well established, its diabetogenic potential and associated metabolic disturbances have not been reported. Diet-induced hamster models of insulin resistance and dyslipidemia were employed to determine lipogenic and diabetogenic effects of dietary cholesterol. Metabolic studies were conducted in hamsters fed diets rich in fructose (40%), fat (30%), and cholesterol (0.05-0.25%) (FFC) and other test diets. Short-term feeding of the FFC diet induced insulin resistance, glucose intolerance, hypertriglyceridemia, and hypercholesterolemia. Prolonged feeding (6-22 wk) of the FFC diet led to severe hepatic steatosis, glucose intolerance, and mild increases in fasting blood glucose, suggesting progression toward type 2 diabetes, but did not induce beta-cell dysfunction. Metabolic changes induced by the diet, including dyslipidemia and insulin resistance, were cholesterol concentration dependent and were only markedly induced on a high-fructose and high-fat dietary background. There were significant increases in hepatic and plasma triglyceride with FFC feeding, likely due to a 10- to 15-fold induction of hepatic stearoyl-CoA desaturase compared with chow levels (P < 0.03). Hepatic insulin resistance was evident based on reduced tyrosine phosphorylation of the insulin receptor-beta, IRS-1, and IRS-2 as well as increased protein mass of protein tyrosine phosphatase 1B. Interestingly, nuclear liver X receptor (LXR) target genes such as ABCA1 were upregulated on the FFC diet, and dietary supplementation with an LXR agonist (instead of dietary cholesterol) worsened dyslipidemia, glucose intolerance, and upregulation of target mRNA and proteins similar to that of dietary cholesterol. In summary, these data clearly implicate dietary cholesterol, synergistically acting with dietary fat and fructose, as a major determinant of the severity of metabolic disturbances in the hamster model. Dietary cholesterol appears to induce hepatic cholesterol ester and triglyceride accumulation, and diet-induced LXR activation (via cholesterol-derived oxysterols) may possibly be one key underlying mechanism.


Assuntos
Colesterol na Dieta/farmacologia , Fígado Gorduroso/metabolismo , Resistência à Insulina , Animais , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Cricetinae , Gorduras na Dieta/farmacologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Fígado Gorduroso/patologia , Frutose/farmacologia , Resistência à Insulina/fisiologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/fisiologia , Lipídeos/sangue , Masculino , Mesocricetus , Doenças Metabólicas/etiologia , Triglicerídeos/sangue , Triglicerídeos/metabolismo
6.
J Crohns Colitis ; 13(10): 1343-1350, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-30918959

RESUMO

BACKGROUND: Patients with Crohn's disease [CD] and ulcerative colitis [UC] are at increased risk for colorectal dysplasia [CRD] and colorectal cancer [CRC]. Adherence to CRC surveillance guidelines is reportedly low internationally. AIM: To evaluate surveillance practices at the tertiary IBD Center of the McGill University Health Center [MUHC] and to determine CRD/CRC incidence. METHODS: A representative inflammatory bowel disease cohort with at least 8 years of disease duration [or with primary sclerosing cholangitis] who visited the MUHC between July 1 and December 31, 2016 were included. Adherence to surveillance guidelines was compared to modified 2010 British Society of Gastroenterology guidelines. Incidence rates of CRC, high-grade dysplasia [HGD], low-grade dysplasia [LGD] and colorectal adenomas [CRA] were calculated based on pathology. RESULTS: In total, 1356 CD and UC patients (disease duration: 12 [interquartile range: 6-22) and 10 [interquartile range: 5-19] years) were identified. The surveillance cohort consisted of 680 patients [296 UC and 384 CD]. Adherence to surveillance guidelines was 76/82% in UC/colonic CD. An adequate number of biopsies were taken in 54/54% of UC/colonic CD patients. The incidence of CRC/HGD in UC and CD with colonic involvement was 19.5/58.5 and 25.1/37.6 per 100,000 patient-years, respectively. The incidence of dysplasia before 8 years of disease duration was low in both UC/CD [19.5 and 12.5/100,000 patient-years] with no CRC detected. The CRA rate was 30/38% in UC/colonic CD. CONCLUSION: High adherence to surveillance guidelines and low CRC and dysplasia, but not CRA rates were found, suggesting that adhering to updated, stratified, surveillance recommendations may result in low advanced neoplasia rates. The incidence of dysplasia before the start of surveillance was low.


Assuntos
Neoplasias Colorretais/diagnóstico , Detecção Precoce de Câncer/estatística & dados numéricos , Fidelidade a Diretrizes/estatística & dados numéricos , Doenças Inflamatórias Intestinais/complicações , Lesões Pré-Cancerosas/diagnóstico , Adulto , Colonoscopia/estatística & dados numéricos , Neoplasias Colorretais/epidemiologia , Feminino , Humanos , Incidência , Doenças Inflamatórias Intestinais/terapia , Masculino , Pessoa de Meia-Idade , Lesões Pré-Cancerosas/epidemiologia , Estudos Retrospectivos
7.
J Crohns Colitis ; 13(9): 1138-1147, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-30793162

RESUMO

BACKGROUND AND AIMS: Measuring quality of care [QoC] in inflammatory bowel diseases [IBD] has become increasingly important, yet complex assessment of QoC from the patients' perspective is rare. We evaluated perceived QoC using the Quality of Care Through the Patient's Eyes-IBD [QUOTE-IBD] questionnaire, and investigated associations between QoC, disease phenotype, work productivity, and health-related quality of life [HRQoL] in a high-volume IBD centre. METHODS: Consecutive patients attending McGill University Health Centre [MUHC]-IBD Centre completed the QUOTE-IBD, Short Inflammatory Bowel Disease Questionnaire [SIBDQ], IBD-Control, and Work Productivity and Activity Impairment [WPAI] questionnaires. The QUOTE-IBD comprises 23 questions, each rated by a quality impact [QI] score. QI scores were calculated for the evaluation of IBD specialists, general practitioners [GPs], and hospital care. RESULTS: In all, 525 patients completed the questionnaire. Total QI scores for IBD specialists, GPs, and hospital care were 8.57, 8.70, and 8.33, respectively. The lowest QI scores were related to 'accessibility' for both IBD specialists and GPs. Female gender, current disease activity, poor HRQoL [SIBDQ score ≤50], and poor disease control [IBD-Control score <13] were associated with lower mean QI scores [p <0.001 for all]. Disease phenotype was not associated with QI scores in either Crohn's disease [CD] or ulcerative colitis [UC] [p = 0.69, p = 0.791, respectively]. An inverse correlation was found between total QI scores and work productivity loss [IBD specialist: p <0.001; GP: p = 0.004]. CONCLUSIONS: Overall patient satisfaction with QoC was good; however, improving patient accessibility to care is warranted. Disease phenotype was not associated with patient satisfaction, whereas female gender, current disease activity, HRQoL, and work productivity loss were associated with patients' quality assessment, underlining that perceived QoC could be partly subjective regarding disease control and quality of life.


Assuntos
Emprego/estatística & dados numéricos , Doenças Inflamatórias Intestinais/terapia , Qualidade da Assistência à Saúde , Qualidade de Vida , Atividades Cotidianas , Adolescente , Adulto , Colite Ulcerativa/patologia , Colite Ulcerativa/terapia , Doença de Crohn/patologia , Doença de Crohn/terapia , Emprego/psicologia , Feminino , Humanos , Doenças Inflamatórias Intestinais/patologia , Masculino , Satisfação do Paciente , Fenótipo , Estudos Prospectivos , Qualidade da Assistência à Saúde/estatística & dados numéricos , Fatores Sexuais , Inquéritos e Questionários , Adulto Jovem
8.
Dig Liver Dis ; 51(3): 340-345, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30591367

RESUMO

BACKGROUND AND AIMS: We aimed to evaluate the quality of care at a tertiary inflammatory bowel disease (IBD) center using quality of care indicators (QIs) including patient assessment strategy, monitoring, treatment decisions and outcomes. METHODS: We retrospectively reviewed the quality of care pre- and post-referral and during follow-up at the at the McGill University Health Center (MUHC) IBD center. Consecutive patients were included presenting with an outpatient visit ('index visit') between July and December 2016. Disease characteristics, biochemistry, imaging and endoscopy data, changes in medications, and vaccination profiles were captured. RESULTS: 1357 patients were included. At referral, a large proportion of patients were objectively re-evaluated (ileocolonoscopy: 79%, cross-sectional imaging: 39.3%, biomarkers: 89.9%, 81.9%). Therapeutic strategy was changed in 53.6% with 22.5% of patients starting biologics. Tight objective patient monitoring was applied during follow-up (colonoscopy: 79%, cross-sectional imaging: 61.8% were available at index visit; C-reactive protein: 78%, Faecal calprotectin: 37.6%, therapeutic drug monitoring: 16.3% were performed additionally). Maximum therapeutic step was biologicals in 48.8% of the patients, while only 6.6% of all patients were steroid dependent. Implementation of a rapid access clinic improved healthcare delivery. CONCLUSIONS: Our data support that tight monitoring was applied at the MUHC IBD center with a high emphasis on objective patient (re)evaluation, timely access and accelerated treatment strategy at referral and during follow-up.


Assuntos
Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/terapia , Indicadores de Qualidade em Assistência à Saúde , Adulto , Biomarcadores/análise , Proteína C-Reativa/análise , Canadá , Colonoscopia , Fezes/química , Feminino , Humanos , Complexo Antígeno L1 Leucocitário/análise , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Encaminhamento e Consulta , Estudos Retrospectivos , Centros de Atenção Terciária
9.
Patient Educ Couns ; 101(2): 331-339, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28760459

RESUMO

OBJECTIVES: This study aims to characterize the relationships between the quality of the information given by the physician, the involvement of the patient in shared decision making (SDM), and outcomes in terms of satisfaction and anxiety pertaining to the treatment of inflammatory bowel disease (IBD). METHODS: A Web survey was conducted among 200 Canadian patients affected with IBD. The theoretical model of SDM was adjusted using path analysis. SAS software was used for all statistical analyses. RESULTS: The quality of the knowledge transfer between the physician and the patient is significantly associated with the components of SDM: information comprehension, patient involvement and decision certainty about the chosen treatment. In return, patient involvement in SDM is significantly associated with higher satisfaction and, as a result, lower anxiety as regards treatment selection. CONCLUSIONS: This study demonstrates the importance of involving patients in shared treatment decision making in the context of IBD. PRACTICE IMPLICATIONS: Understanding shared decision making may motivate patients to be more active in understanding the relevant information for treatment selection, as it is related to their level of satisfaction, anxiety and adherence to treatment. This relationship should encourage physicians to promote shared decision making.


Assuntos
Ansiedade/psicologia , Tomada de Decisões , Doenças Inflamatórias Intestinais/terapia , Participação do Paciente , Relações Médico-Paciente , Adulto , Atitude do Pessoal de Saúde , Canadá , Feminino , Humanos , Doenças Inflamatórias Intestinais/psicologia , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Percepção
10.
Public Health Genomics ; 20(3): 174-187, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28813717

RESUMO

In this study, we contribute to the personalized medicine and health care management literature by developing and testing a new participative design approach. We propose that involving gastroenterologists in the development of a predictive test to assist them in their clinical decision-making process for the treatment of inflammatory bowel diseases will increase the likelihood of their acceptance of the innovation. Based on data obtained from 6 focus groups across Canada from a total of 28 physicians, analyses reveal that current tools do not enable discriminating between treatment options to find the best fit for each patient. Physicians expect a new predictive tool to have the capability of showing clear reliability and significant benefits for the patient, while being accessible in a timely manner that facilitates clinical decisions. Physicians also insist on their key role in the implementation process, hence confirming the relevance and importance of participative designs in personalized medicine.


Assuntos
Gastroenterologistas , Doenças Inflamatórias Intestinais/terapia , Medicina de Precisão/métodos , Adulto , Idoso , Canadá , Tomada de Decisão Clínica/métodos , Feminino , Grupos Focais , Humanos , Masculino , Pessoa de Meia-Idade , Participação do Paciente , Papel do Médico , Padrões de Prática Médica , Reprodutibilidade dos Testes
11.
PLoS One ; 8(12): e81870, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24339975

RESUMO

Modulation of mitochondrial function through inhibiting respiratory complex I activates a key sensor of cellular energy status, the 5'-AMP-activated protein kinase (AMPK). Activation of AMPK results in the mobilization of nutrient uptake and catabolism for mitochondrial ATP generation to restore energy homeostasis. How these nutrient pathways are affected in the presence of a potent modulator of mitochondrial function and the role of AMPK activation in these effects remain unclear. We have identified a molecule, named R419, that activates AMPK in vitro via complex I inhibition at much lower concentrations than metformin (IC50 100 nM vs 27 mM, respectively). R419 potently increased myocyte glucose uptake that was dependent on AMPK activation, while its ability to suppress hepatic glucose production in vitro was not. In addition, R419 treatment of mouse primary hepatocytes increased fatty acid oxidation and inhibited lipogenesis in an AMPK-dependent fashion. We have performed an extensive metabolic characterization of its effects in the db/db mouse diabetes model. In vivo metabolite profiling of R419-treated db/db mice showed a clear upregulation of fatty acid oxidation and catabolism of branched chain amino acids. Additionally, analyses performed using both (13)C-palmitate and (13)C-glucose tracers revealed that R419 induces complete oxidation of both glucose and palmitate to CO2 in skeletal muscle, liver, and adipose tissue, confirming that the compound increases mitochondrial function in vivo. Taken together, our results show that R419 is a potent inhibitor of complex I and modulates mitochondrial function in vitro and in diabetic animals in vivo. R419 may serve as a valuable molecular tool for investigating the impact of modulating mitochondrial function on nutrient metabolism in multiple tissues and on glucose and lipid homeostasis in diabetic animal models.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Diabetes Mellitus Experimental/metabolismo , Mitocôndrias Hepáticas/metabolismo , Células Musculares/metabolismo , Aminoácidos de Cadeia Ramificada/metabolismo , Animais , Diabetes Mellitus Experimental/patologia , Ativação Enzimática/efeitos dos fármacos , Ácidos Graxos/metabolismo , Glucose/metabolismo , Células Hep G2 , Humanos , Hipoglicemiantes/farmacologia , Metformina/farmacologia , Camundongos , Mitocôndrias Hepáticas/patologia , Células Musculares/patologia , Oxirredução/efeitos dos fármacos , Palmitatos/farmacologia , Inibidores de Proteínas Quinases/farmacologia
12.
Arch Biochem Biophys ; 465(2): 380-8, 2007 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-17698027

RESUMO

Although insulin normally activates global mRNA translation, it has a specific inhibitory effect on translation of apolipoprotein B (apoB) mRNA. This suggests that insulin induces a unique signaling cascade that leads to specific inhibition of apoB mRNA translation despite global translational stimulation. Recent studies have revealed that insulin functions to regulate apoB mRNA translation through a mechanism involving the apoB mRNA 5' untranslated region (5' UTR). Here, we further investigate the role of downstream insulin signaling molecules on apoB mRNA translation, and the mechanism of apoB mRNA translation itself. Transfection studies in HepG2 cells expressing deletion constructs of the apoB 5' UTR showed that the cis-acting region responding to insulin was localized within the first 64 nucleotides. Experiments using chimeric apoB UTR-luciferase constructs transfected into HepG2 cells followed by treatment with wortmannin, a PI-3K inhibitor, and rapamycin, an mTOR inhibitor, showed that signaling via PI-3K and mTOR pathways is necessary for insulin-mediated inhibition of chimeric 5' UTR-luciferase expression. In vitro translation of chimeric cRNA confirmed that the effects observed were translational in nature. Furthermore, using RNA-EMSA we found that wortmannin pretreatment blocked insulin-mediated inhibition of the binding of RNA-binding factor(s), migrating near the 110 kDa marker, to the 5' UTR. Radiolabeling studies in HepG2 cells also showed that insulin-mediated control of the synthesis of endogenously expressed full length apoB100 is mediated via the PI-3K and mTOR pathways. Finally, using dual-cistronic luciferase constructs we demonstrate that apoB 5' UTR may have weak internal ribosomal entry (IRES) translation which is not affected by insulin stimulation, and may function to stimulate basal levels of apoB mRNA translation.


Assuntos
Apolipoproteínas B/metabolismo , Hepatócitos/metabolismo , Insulina/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Biossíntese de Proteínas/fisiologia , Proteínas Quinases/metabolismo , Ribossomos/metabolismo , Linhagem Celular , Humanos , Proteínas Ribossômicas/metabolismo , Transdução de Sinais/fisiologia , Serina-Treonina Quinases TOR
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