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Quantitative assessments of tumor burden and modeling of longitudinal growth could improve phase II oncology trials. To identify obstacles to wider use of quantitative measures we obtained recorded linear tumor measurements from three published lung cancer trials. Model-based parameters of tumor burden change were estimated and compared with similarly sized samples from separate trials. Time-to-tumor growth (TTG) was computed from measurements recorded on case report forms and a second radiologist blinded to the form data. Response Evaluation Criteria in Solid Tumors (RECIST)-based progression-free survival (PFS) measures were perfectly concordant between the original forms data and the blinded radiologist re-evaluation (intraclass correlation coefficient = 1), but these routine interrater differences in the identification and measurement of target lesions were associated with an average 18-week delay (range, -20 to 55 weeks) in TTG (intraclass correlation coefficient = 0.32). To exploit computational metrics for improving statistical power in small clinical trials will require increased precision of tumor burden assessments.
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Determinación de Punto Final , Modelos Biológicos , Neoplasias/diagnóstico por imagen , Neoplasias/patología , Criterios de Evaluación de Respuesta en Tumores Sólidos , Tomografía Computarizada por Rayos X , Proliferación Celular , Ensayos Clínicos como Asunto , Supervivencia sin Enfermedad , Humanos , Cinética , Control de Calidad , Carga TumoralRESUMEN
INTRODUCTION: Due to high inter-individual variability in peripheral pharmacokinetic parameters, dosing of antipsychotics currently relies on clinical trial-and-error, and predicting antipsychotic plasma concentrations before changing a dose has been a challenge. METHODS: Patients with schizophrenia receiving a stable dose of olanzapine were included. 2 plasma samples were collected at 2 given time points for the measurement of plasma olanzapine concentrations. At least 7 days after a dosage change of olanzapine, a third sample was collected. The plasma concentration of the third sample was predicted in a blinded fashion using a mixed-effects model with NONMEM(®), using the following information: the 2 baseline plasma concentrations, the interval between the last dose and blood draw, and clinical and demographic information. RESULTS: 31 subjects (mean±SD age=56.0±11.6; 19 men) were enrolled. The mean prediction (95% confidence interval) errors were 1.6 (-2.8 to 6.0) ng/mL. A highly significant correlation was observed between the observed and predicted concentrations of the third sample (r=0.91, p<0.001). DISCUSSION: Plasma olanzapine concentrations following an actual dosage change can be predicted in advance with a high degree of certainty.
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Antipsicóticos/farmacocinética , Benzodiazepinas/farmacocinética , Esquizofrenia/tratamiento farmacológico , Adulto , Anciano , Antipsicóticos/administración & dosificación , Antipsicóticos/sangre , Benzodiazepinas/administración & dosificación , Benzodiazepinas/sangre , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Masculino , Persona de Mediana Edad , Olanzapina , Esquizofrenia/sangreRESUMEN
To improve future drug development efficiency in renal cell carcinoma (RCC), a disease-progression model was developed with longitudinal tumor size data from a phase III trial of sorafenib in RCC. The best-fit model was externally evaluated on 145 placebo-treated patients in a phase III trial of pazopanib; the model incorporated baseline tumor size, a linear disease-progression component, and an exponential drug effect (DE) parameter. With the model-estimated effect of sorafenib on RCC growth, we calculated the power of randomized phase II trials between sorafenib and hypothetical comparators over a range of effects. A hypothetical comparator with 80% greater DE than sorafenib would have 82% power (one-sided α = 0.1) with 50 patients per arm. Model-based quantitation of treatment effect with computed tomography (CT) imaging offers a scaffold on which to develop new, more efficient, phase II trial end points and analytic strategies for RCC.
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Carcinoma de Células Renales/tratamiento farmacológico , Ensayos Clínicos Fase III como Asunto/estadística & datos numéricos , Progresión de la Enfermedad , Neoplasias Renales/tratamiento farmacológico , Modelos Estadísticos , Niacinamida/análogos & derivados , Compuestos de Fenilurea/uso terapéutico , Antineoplásicos/uso terapéutico , Ensayos Clínicos Fase II como Asunto/estadística & datos numéricos , Niacinamida/uso terapéutico , SorafenibRESUMEN
There is considerable interindividual variability in the growth of abdominal aortic aneurysms (AAAs), but an individual's growth observations, risk factors, and biomarkers could potentially be used to tailor surveillance. To assess the potential for tailoring surveillance, this study determined the accuracy of individualized predictions of AAA size at the next surveillance observation. A hierarchical Bayesian model was fitted to a total of 1,732 serial ultrasound measurements from 299 men in whom ultrasound screening identified an AAA. The data were best described by a nonlinear model with a constant first derivative of the AAA growth rate with size. The area under the receiver operating characteristic (ROC) curves for predicting whether an AAA was ≥40 or ≥50 mm at the next observation were 0.922 and 0.979, respectively, and the median root mean squared error was 2.52 mm. These values were nearly identical for models with or without plasma D-dimer effects.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e12; doi:10.1038/psp.2012.13; advance online publication 24 October 2012.
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Sirolimus, the prototypical inhibitor of the mammalian target of rapamycin, has substantial antitumor activity. In this study, sirolimus showed nonlinear pharmacokinetic characteristics over a wide dose range (from 1 to 60 mg/week). The objective of this study was to develop a population pharmacokinetic (PopPK) model to describe the nonlinearity of sirolimus. Whole blood concentration data, obtained from four phase I clinical trials, were analyzed using a nonlinear mixed-effects modeling (NONMEM) approach. The influence of potential covariates was evaluated. Model robustness was assessed using nonparametric bootstrap and visual predictive check approaches. The data were well described by a two-compartment model incorporating a saturable Michaelis-Menten kinetic absorption process. A covariate analysis identified hematocrit as influencing the oral clearance of sirolimus. The visual predictive check indicated that the final pharmacokinetic model adequately predicted observed concentrations. The pharmacokinetics of sirolimus, based on whole blood concentrations, appears to be nonlinear due to saturable absorption.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e17; doi:10.1038/psp.2012.18; advance online publication 5 December 2012.
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The antipsychotic drug, olanzapine, one of the most widely used drugs in clinical medicine, has a high rate of discontinuation due to inefficacy and/or adverse effects. We identified a single nucleotide polymorphism in the drug metabolizing enzyme, cytochrome P450 3A43 (CYP3A43; rs472660), that highly significantly predicted olanzapine clearance in the Clinical Antipsychotic Trials of Intervention Effectiveness trial (P=5.9e(-7)). Moreover, at standard antipsychotic doses, 50% of individuals with the high clearance genotype (AA) have trough blood levels below the therapeutic range. Interestingly, a much higher proportion of African Americans carry the A allele compared with Caucasians (allele frequency 67 vs 14%). After accounting for CYP3A43 genotype, race is no longer a significant predictor of olanzapine clearance. Olanzapine clearance was associated with measures of clinical response. Patients with greater clearance had higher symptom ratings and were more likely to discontinue treatment due to an inadequate response. Our data identify a genetic mechanism for variation in olanzapine response and demonstrate that blood level monitoring of olanzapine treatment is advisable.
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Antipsicóticos/farmacocinética , Benzodiazepinas/farmacocinética , Negro o Afroamericano/genética , Citocromo P-450 CYP3A/genética , Polimorfismo de Nucleótido Simple/genética , Población Blanca/genética , Antipsicóticos/uso terapéutico , Benzodiazepinas/uso terapéutico , Femenino , Frecuencia de los Genes , Genotipo , Glucosa/metabolismo , Humanos , Modelos Lineales , Metabolismo de los Lípidos/efectos de los fármacos , Masculino , Modelos Químicos , Olanzapina , Escalas de Valoración Psiquiátrica , Esquizofrenia/tratamiento farmacológico , Esquizofrenia/metabolismo , Factores Sexuales , Fumar/genética , Aumento de Peso/efectos de los fármacosRESUMEN
This study was undertaken to characterize the pharmacokinetics and bioavailability of voriconazole in adult lung transplant patients during the early postoperative period, identify factors significantly associated with various pharmacokinetic parameters, and make recommendations for adequate dosing regimens. Thirteen lung transplant patients received two intravenous infusions (6 mg/kg, twice daily [b.i.d.]) immediately posttransplant followed by oral doses (200 mg, b.i.d.) for prophylaxis. Blood samples (9/interval) were collected during one intravenous and one oral dosing interval from each patient. Voriconazole plasma concentrations were measured by high-pressure liquid chromatography (HPLC). NONMEM was used to develop pharmacokinetic models, evaluate covariate relationships, and perform Monte Carlo simulations. There was a good correlation (R(2) = 0.98) between the area under the concentration-time curve specific for the dose evaluated (AUC(0-∞)) and trough concentrations. A two-compartment model adequately described the data. Population estimates of bioavailability, clearance, V(c), and V(p) were 45.9%, 3.45 liters/h, 54.7 liters, and 143 liters. Patients with cystic fibrosis (CF) exhibited a significantly lower bioavailability (23.7%, n = 3) than non-CF patients (63.3%, n = 10). Bioavailability increased with postoperative time and reached steady levels in about 1 week. V(p) increased with body weight. Bioavailability of voriconazole is substantially lower in lung transplant patients than non-transplant subjects but significantly increases with postoperative time. CF patients exhibit significantly lower bioavailability and exposure of voriconazole and therefore need higher doses. Intravenous administration of voriconazole during the first postoperative day followed by oral doses of 200 mg or 400 mg appeared to be the optimal dosing regimen. However, voriconazole levels should be monitored, and the dose should be individualized based on trough concentrations as a good measure of drug exposure.
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Antifúngicos/farmacocinética , Pirimidinas/farmacocinética , Triazoles/farmacocinética , Adulto , Anciano , Antifúngicos/sangre , Antifúngicos/uso terapéutico , Disponibilidad Biológica , Femenino , Humanos , Trasplante de Pulmón , Masculino , Persona de Mediana Edad , Pirimidinas/sangre , Pirimidinas/uso terapéutico , Triazoles/sangre , Triazoles/uso terapéutico , Voriconazol , Adulto JovenRESUMEN
Antipsychotic medications are the standard of care for both acute and maintenance treatment of schizophrenia, the latter requiring an indefinite treatment across a patient's life span. However, dosing and tolerability of antipsychotics have been studied primarily in younger patients, and very limited data are available for age- and phase-specific dosing. This leaves the clinician with no guidance on dose adjustment as patients grow older-an issue of critical importance, especially in light of recent concerns about increased morbidity and mortality associated with antipsychotics.
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Envejecimiento , Antipsicóticos/administración & dosificación , Esquizofrenia/tratamiento farmacológico , Antipsicóticos/efectos adversos , Antipsicóticos/uso terapéutico , Enfermedades de los Ganglios Basales/inducido químicamente , Relación Dosis-Respuesta a Droga , Humanos , Tomografía de Emisión de Positrones , Receptores Dopaminérgicos/metabolismo , Esquizofrenia/diagnóstico por imagenRESUMEN
The application of mathematical models to reflect the organization and activity of biological systems can be viewed as a continuum of purpose. The far left of the continuum is solely the prediction of biological parameter values, wherein an understanding of the underlying biological processes is irrelevant to the purpose. At the far right of the continuum are mathematical models, the purposes of which are a precise understanding of those biological processes. No models in present use fall at either end of the continuum. Without question, however, the emphasis in regards to purpose has been on prediction, e.g., clinical trial simulation and empirical disease progression modeling. Clearly the model that ultimately incorporates a universal understanding of biological organization will also precisely predict biological events, giving the continuum the logical form of a tautology. Currently that goal lies at an immeasurable distance. Nonetheless, the motive here is to urge movement in the direction of that goal. The distance traveled toward understanding naturally depends upon the nature of the scientific question posed with respect to comprehending and/or predicting a particular disease process. A move toward mathematical models implies a move away from static empirical modeling and toward models that focus on systems biology, wherein modeling entails the systematic study of the complex pattern of organization inherent in biological systems.
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Comprensión , Enfermedad , Modelos Biológicos , Modelos Teóricos , Animales , Humanos , Matemática , Biología de Sistemas/métodosRESUMEN
STUDY OBJECTIVE: To describe the clinical use and safety of continuous infusion (CI) enoxaparin in a naturalistic setting and to evaluate the influence of renal function on enoxaparin elimination. DESIGN: Retrospective medical record review. SETTING: 1000-bed tertiary care teaching centre. PATIENTS: Hospitalized patients that received enoxaparin by CI during a 2-year period. INTERVENTIONS: None. MEASUREMENTS: Specific details of dosage and monitoring were collected. Adverse drug reactions (ADR) were recorded. Creatinine clearance (CrCl) was calculated using Cockroft and Gault and Brater equations. A population pharmacokinetic analysis was performed using the non-linear mixed effect model (NONMEM). For patients located in the intensive care unit (ICU) and ward, POSTHOC pharmacokinetic parameter estimates were evaluated using the Wilcoxon rank-sum. Pearson correlation coefficient was calculated to determine the association between renal function and anti-Xa clearance. MAIN RESULTS: Sixty-seven patients received enoxaparin by CI of which 61.2% were in the ward and 38.8% in the ICU. The average initial rate and duration of infusion were 5.2 mg/h and 5.6 days, respectively. The number of anti-Xa concentration measurements averaged five per patient. Nine patients experienced an ADR. The most frequent ADR was gastrointestinal bleeding (n = 4). Among the 67 patients, 48 had available anti-Xa concentrations and were included in the NONMEM model. The anti-Xa CL and volume of distribution for ICU and ward patients averaged 0.64 +/- 0.34 L/h, 10.6 +/- 1.55 L and 1.01 +/- 0.39 L/h, 9.08 +/- 1.17 L, respectively. CrCl was not a significant covariate when included in the NONMEM model, and the association between CrCl and anti-Xa clearance was not significant (R2 = 0.0005; P = 0.8916). CONCLUSIONS: This study is the first to report the use and safety of prolonged CI enoxaparin. Pharmacokinetic parameters of enoxaparin differ in ICU vs. ward patients. Overall, we found the safety of CI to be comparable to subcutaneous administration. Also, we found no effect of renal function on enoxaparin elimination.
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Anticoagulantes/efectos adversos , Creatinina/metabolismo , Enoxaparina/efectos adversos , Riñón/fisiopatología , Insuficiencia Renal/metabolismo , Anticoagulantes/administración & dosificación , Anticoagulantes/farmacocinética , Monitoreo de Drogas , Enoxaparina/administración & dosificación , Enoxaparina/farmacocinética , Inhibidores del Factor Xa , Femenino , Hospitales con más de 500 Camas , Hospitales , Hospitales Universitarios , Humanos , Infusiones Intravenosas , Unidades de Cuidados Intensivos , Pruebas de Función Renal , Masculino , Sistemas de Registros Médicos Computarizados , Persona de Mediana Edad , Insuficiencia Renal/fisiopatología , Estudios RetrospectivosRESUMEN
This study investigated the relationships between blame, victim and offender status, and the pursuit of revenge or reconciliation after a personal offense. Results from a sample of 141 government agency employees showed that blame is positively related to revenge and negatively related to reconciliation. In addition, victim-offender relative status moderated the relation between blame and revenge such that victims who blamed sought revenge more often when the offender's status was lower than their own. The victims' own absolute hierarchical status also moderated this relation such that lower, not higher, status employees who blamed sought revenge more often.
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Agresión , Víctimas de Crimen , Hostilidad , Relaciones Interpersonales , Clase Social , Lugar de Trabajo , Adulto , Femenino , Humanos , Masculino , Encuestas y CuestionariosRESUMEN
Previous studies have demonstrated that environmentally or genetically induced changes in the intracellular proteins that compose the cytoskeleton can contribute to heart failure. Because neonatal right ventricular myocytes are immature and are in the process of significant cytoskeletal change, we hypothesized that they may be particularly susceptible to pressure stress. Newborn calves exposed to hypobaric hypoxia (barometric pressure = 430 mmHg) for 14 days developed severe pulmonary hypertension (pulmonary arterial pressure = 101 +/- 6 vs. 27 +/- 1 mmHg) and right heart failure compared with age-matched controls. Light microscopy showed partial loss of myocardial striations in the failing neonatal right but not left ventricles and in neither ventricle of adolescent cattle dying of altitude-induced right heart failure. In neonatal calves, immunohistochemical analysis of the cytoskeletal proteins (vinculin, metavinculin, desmin, vimentin, and cadherin) showed selectively, within the failing right ventricles, patchy areas characterized by loss and disorganization of costameres and intercalated discs. Within myocytes from the failing ventricles, vinculin and desmin were observed to redistribute diffusely within the cytosol, metavinculin appeared in disorganized clumps, and vimentin immunoreactivity was markedly decreased. Western blot analysis of the failing right ventricular myocardium showed, compared with control, vinculin and desmin to be little changed in total content but redistributed from insoluble (structural) to soluble (cytosolic) fractions; metavinculin total content was markedly decreased, tubulin content increased, particularly in the structural fraction, and cadherin total content and distribution were unchanged. We conclude that hypoxic pulmonary hypertensive-induced neonatal right ventricular failure is associated with disorganization of the cytoskeletal architecture.
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Citoesqueleto/ultraestructura , Insuficiencia Cardíaca/patología , Hipertensión Pulmonar/complicaciones , Hipoxia/complicaciones , Miocardio/patología , Animales , Animales Recién Nacidos , Cadherinas/metabolismo , Bovinos , Ecocardiografía , Técnica del Anticuerpo Fluorescente , Insuficiencia Cardíaca/diagnóstico por imagen , Insuficiencia Cardíaca/etiología , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/patología , Hemodinámica , Inmunohistoquímica , Proteínas de Filamentos Intermediarios/metabolismo , Masculino , Proteínas Musculares/metabolismo , Miocardio/metabolismo , Tamaño de los ÓrganosRESUMEN
The role of microtubules in modulating cardiomyocyte beta-adrenergic response was investigated in rats with cardiac hypertrophy. Male Sprague-Dawley rats underwent stenosis of the abdominal aorta (hypertensive, HT) or sham operation (normotensive, NT). Echocardiography and isolated left ventricular cardiomyocyte dimensions demonstrated cardiac hypertrophy in the HT rats after 30 wk. Cardiomyocyte microtubule fraction was assayed by high-speed centrifugation and Western blot. In contrast to previous reports of increased microtubules after acute pressure overload, microtubule fraction for HT was significantly lower than that for NT. Cardiomyocytes were exposed to either 1 microM colchicine, 10 microM taxol, or equivalent volume of vehicle. Colchicine decreased microtubules, and taxol increased microtubules in both groups. Cardiomyocyte cytosolic calcium ([Ca2+]c) and shortening/relaxation dynamics were assessed during exposure to increasing isoproterenol concentrations. The beta-adrenergic response for these variables in the HT group was blunted compared with NT. However, increased microtubule assembly by taxol partially recovered the normal beta-adrenergic response for time to peak [Ca2+]c, time to peak shortening, and mechanical relaxation variables. Microtubule assembly may play a significant role in determining cardiomyocyte beta-adrenergic response in chronic cardiac hypertrophy.
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Cardiomegalia/fisiopatología , Microtúbulos/fisiología , Receptores Adrenérgicos beta/fisiología , Animales , Calcio/metabolismo , Cardiomegalia/patología , Colchicina/farmacología , Colorantes Fluorescentes , Fura-2 , Masculino , Miocardio/ultraestructura , Paclitaxel/farmacología , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
BACKGROUND: Heat shock proteins (hsp) constitute an endogenous stress response that protects cells from injury. Most work on these important proteins has focused on the immediate response to acute stress in cell culture systems and mammalian models of heart disease. Little is known about the expression of the hsps in human hearts. We were interested in whether there was increased expression of the hsps in heart failure, a setting of chronic, sustained stress. Five different hsps were examined: hsp27, hsp60, hsp72, hsc70 and hsp90. METHODS AND RESULTS: Three groups of explanted hearts were studied: dilated cardiomyopathy (DCM), ischemic cardiomyopathy (IHD), and normal controls. Western-blotting with a standard curve of purified protein on each blot was used to quantify the expression of the hsps. Hsp27 was increased almost two-fold in DCM compared to normal hearts, and was significantly greater than in IHD hearts. Levels of hsp60 were doubled in both DCM and IHD hearts (P < 0.05). Hsp72, hsc70 and hsp90 were not significantly changed. CONCLUSIONS: This study shows for the first time that differential changes in hsp levels occur in end-stage heart failure. Since hsps can render cells resistant to apoptosis, and are associated with the mitochondria and the cytoskeleton, which are known to be abnormal in heart failure, these studies may lead to new insights into the pathogenesis of cardiac decompensation.
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Cardiomiopatía Dilatada/metabolismo , Proteínas HSP70 de Choque Térmico , Proteínas de Choque Térmico/biosíntesis , Isquemia Miocárdica/metabolismo , Miocardio/metabolismo , Adulto , Proteínas Portadoras/biosíntesis , Chaperonina 60/biosíntesis , Femenino , Expresión Génica , Proteínas del Choque Térmico HSC70 , Proteínas del Choque Térmico HSP72 , Proteínas HSP90 de Choque Térmico/biosíntesis , Humanos , Péptidos y Proteínas de Señalización Intracelular , Masculino , Persona de Mediana Edad , Proteínas Serina-Treonina Quinasas/biosíntesisRESUMEN
OBJECTIVES: We sought to compare the short- and long-term mortality rates in patients > or = 70 years old with unstable angina undergoing percutaneous transluminal coronary angioplasty (PTCA) with predicted coronary artery bypass graft surgery (CABG) short-term and U.S. census long-term mortality rates. BACKGROUND: Coronary angioplasty is an alternative revascularization strategy for patients with medically refractory rest angina and a high risk of adverse outcomes with CABG. Patients > or = 70 years old are a specific high risk subset. METHODS: A total of 131 consecutive patients aged > or = 70 years with unstable angina underwent PTCA; 82 (62%) of 131 had been refused CABG. Mortality over time was obtained from the Veterans Affairs Beneficiary Index Records Locator Subsystem. Predicted 30-day CABG-associated mortality was obtained from the Veterans Affairs Cardiac Risk Assessment Model. Mortality over time was expressed with Kaplan-Meier curves. RESULTS: The observed 30-day angioplasty survival rate was 87% compared with the predicted surgical 30-day survival rate of 85.5%. In those patients who survived 6 months after angioplasty (84%), their subsequent 1-, 2-, 3-, 4- and 5-year survival rates were comparable to age-matched subjects in the U.S. census. Mortality in certain subsets known to be at very high risk for CABG-for example, patients who had a previous CABG-was not high in this cohort of elderly subjects. The extremely high risk subsets identified in this PTCA cohort (shock, heart failure, pressors required, balloon pump required) were relatively infrequent subsets. CONCLUSIONS: For selected elderly patients with unstable angina deemed to be at "high risk" or even "prohibitive risk" for CABG, PTCA is an alternative revascularization strategy. The long-term mortality of successfully treated elderly patients is comparable to age-matched subjects. A prospective, multicenter, randomized trial of CABG versus PTCA, which includes patients > or = 70 years old, is being conducted (Veterans Affairs Cooperative Study 385: AWESOME).
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Angina Inestable/terapia , Angioplastia Coronaria con Balón , Anciano , Angina Inestable/diagnóstico por imagen , Angina Inestable/mortalidad , Angioplastia Coronaria con Balón/mortalidad , Angiografía Coronaria , Puente de Arteria Coronaria/mortalidad , Humanos , Estudios Retrospectivos , Medición de Riesgo , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
BACKGROUND: The cytoskeleton plays an important role in maintaining cell structure and integrity. Defects in cytoskeletal proteins can cripple cell strength and may cause cardiomyopathy. We analyzed heart tissues from subjects with dilated cardiomyopathy for abnormalities in the cardiac cytoskeleton. Metavinculin, a cardiac isoform of the cytoskeletal protein vinculin, connects actin microfilaments to the intercalated disk and membrane costameres of the heart. METHODS AND RESULTS: Metavinculin and vinculin transcripts and protein were analyzed by polymerase chain reaction (PCR) and Western blotting. Thirty-three human heart specimens were studied, including 5 normal controls, 4 subjects with ischemic cardiomyopathy, 1 with X-linked cardiomyopathy, and 23 with idiopathic dilated cardiomyopathy (IDC). PCR of cardiac cDNA detected absence of the metavinculin transcript in cardiac tissue from a subject with IDC. PCR of genomic DNA showed that the metavinculin exon was present but not utilized in the cardiac transcript. Western blot analysis demonstrated absence of metavinculin protein in the heart from this subject. Immunostaining of cardiac vinculin in this heart showed disorganized intercalated disk structures. Metavinculin deficiency was associated with normal cardiac expression of the cytoskeletal proteins vinculin, alpha-actinin, and dystrophin. Normal metavinculin expression in the other heart specimens suggests that the defect is specific in the IDC subject identified. CONCLUSIONS: These results demonstrate an association between metavinculin deficiency and dilated cardiomyopathy due to a defect in alternative mRNA splicing.
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Cardiomiopatía Dilatada/patología , Miocardio/química , Vinculina/análogos & derivados , Vinculina/deficiencia , Western Blotting , Humanos , Inmunohistoquímica , Reacción en Cadena de la Polimerasa , Vinculina/análisisRESUMEN
5'-mutations in the dystrophin gene can result in cardiomyopathy without clinically-apparent skeletal myopathy. The effect of dystrophin mutations on the assembly and stability of the dystrophin associated protein (DAP) complex in human heart are not fully understood. The molecular defect in the dystrophin complex was explored in a family with an X-linked pedigree and severe dilated cardiomyopathy. Dystrophin gene analysis demonstrated a 5' duplication involving exons 2-7, which encodes the N-terminal actin binding domain of dystrophin. Ribonuclease protection and PCR assays demonstrated a reduction in muscle promoter transcribed dystrophin mRNA in the heart compared to skeletal muscle. A deficiency of cardiac dystrophin protein was observed by Western blot and lack of membrane localization by immunocytochemistry. The cardiac expression of the dystrophin related protein utrophin was increased, and the 43 kDa (beta-dystroglycan), 50 kDa (alpha-sarcoglycan) and 59 kDa (syntrophin) dystrophin associated proteins (DAPs) were co-isolated and present in nearly normal amounts in the membrane. However, cardiac dystrophin deficiency and increased utrophin expression were associated with loss of extracellular 156 kDa dystrophin associated glycoprotein (alpha-dystroglycan) binding to the cardiomyocyte membrane. alpha-Dystroglycan is responsible for linkage of the dystrophin complex to the extracellular matrix protein laminin. Therefore, 5' dystrophin mutations can reduce cardiac dystrophin mRNA, protein expression, and dystrophin function in X-linked cardiomyopathy (XLCM). The presence of membrane-associated beta-dystroglycan, alpha-sarcoglycan, syntrophin, and utrophin are insufficient to maintain cardiac function. This XLCM family has a 5' dystrophin gene mutation resulting in cardiac dystrophin deficiency and a loss of alpha-dystroglycan membrane binding.
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Cardiomiopatía Dilatada/genética , Proteínas del Citoesqueleto/genética , Distrofina/genética , Glicoproteínas de Membrana/genética , Familia de Multigenes , Mutación , Adolescente , Adulto , Cardiomiopatía Dilatada/patología , Membrana Celular/química , Membrana Celular/metabolismo , Proteínas del Citoesqueleto/metabolismo , Distroglicanos , Distrofina/metabolismo , Femenino , Ligamiento Genético , Heterocigoto , Humanos , Masculino , Glicoproteínas de Membrana/metabolismo , Músculo Esquelético/química , Músculo Esquelético/metabolismo , Miocardio/química , Miocardio/metabolismo , Miocardio/patología , Linaje , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , Cromosoma XRESUMEN
Angioplasty of the internal mammary artery (IMA) bypass graft has been shown to be a safe and effective revascularization procedure. However, angiographic and long term clinical outcomes in the high-risk group of patients presenting with rest angina has not been well documented. We report the results of IMA angioplasty in 20 patients with rest angina out of 614 (3.2%) who received a left IMA graft at our institution between April 1987 and September 1994. All patients were admitted with rest angina, 12 patients demonstrated persistent ischemia despite medical therapy, two patients were in heart failure, and one patient was in cardiogenic shock. Balloon angioplasty was successful in 15 of 20 patients (75%). Failed angioplasty was associated with either severe IMA tortuousity (three patients) or inability to cross the anastomotic stenosis with the guide wire (two patients). Each of these five patients required angioplasty of either the native left anterior descending artery or other saphenous vein grafts for clinical stabilization. No patient suffered a major complication (myocardial infarction, emergent coronary bypass surgery, death). Clinical follow-up was obtained in all 20 patients (6 months, 7 years, mean 27 months). Twelve patients (60%) were asymptomatic or had stable angina at follow-up, and 8 returned with anginal symptoms. Four patients required repeat angioplasty for disease in other vessels, two were treated medically for angina, one underwent repeat CABG, and cardiac transplantation was performed in one patient for refractory heart failure. Angiographic follow up was obtained in 10/15 (66%) successful angioplasty patients, and only one patient demonstrated restenosis at the treated site (10%). During follow up one patient developed an IMA stenosis at a previous dissection site in the body of the graft that was treated with angioplasty. These results suggest that IMA angioplasty in patients with rest angina is associated with excellent long term patency and clinical efficacy, as well as low procedural risk.
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Angina Pectoris Variable/terapia , Angioplastia Coronaria con Balón , Arterias Mamarias , Adulto , Anciano , Angina Pectoris Variable/diagnóstico por imagen , Angina Pectoris Variable/fisiopatología , Angiografía , Angiografía Coronaria , Puente de Arteria Coronaria , Femenino , Estudios de Seguimiento , Humanos , Masculino , Arterias Mamarias/diagnóstico por imagen , Arterias Mamarias/trasplante , Persona de Mediana Edad , Cuidados Posoperatorios , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Dystrophin mRNA transcripts from the P (Purkinje) promoter were shown to be differentially expressed in human skeletal muscle, heart, and brain. The expression pattern was characteristic of tissue type and developmental stage. Polymerase chain reaction (PCR) analysis of the P promoter transcripts in adult skeletal muscle and adult brain identified two alternatively spliced sequences, one that encodes a full-length dystrophin mRNA and a second that transcribes a termination codon 27 nucleotides (8 amino acids) after the ATG initiation site. Alternative splicing of this truncated coding transcript was developmentally regulated, and it was expressed as the major form in adult cortical brain and adult heart. The biological significance of this peptide remains unclear. The full-length transcript was the major form in fetal cortical brain and adult skeletal muscle. Ribonuclease protection assay demonstrated that as much as 20% of dystrophin transcription in normal adult skeletal muscle was derived from the full-length transcript from the P promoter. In contrast, adult heart did not express significant levels of P promoter derived transcripts. Thus, transcripts from the P promoter were found to be developmentally regulated in the brain, and its activity was differentially expressed in skeletal versus cardiac muscle tissues. These data show that the P promoter transcript displays a broader scope of expression, regulation, and complexity than previously appreciated.
Asunto(s)
Cerebelo/fisiología , Distrofina/genética , Músculo Esquelético/fisiología , Regiones Promotoras Genéticas/genética , Células de Purkinje/fisiología , Adulto , Empalme Alternativo , Secuencia de Aminoácidos , Secuencia de Bases , Encéfalo/embriología , Química Encefálica , Regulación del Desarrollo de la Expresión Génica/fisiología , Corazón/fisiología , Humanos , Datos de Secuencia Molecular , Músculo Esquelético/química , Músculo Esquelético/embriología , Miocardio/química , Especificidad de Órganos , Sondas ARN , ARN Mensajero/análisisRESUMEN
BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that produces negative inotropic effects in the heart. Recently, elevated levels of TNF-alpha have been reported in patients with advanced congestive heart failure. Although TNF-alpha is thought to exert its deleterious effects by binding to two cell surface receptors, TNFR1 and TNFR2, the level of expression and regulation of TNF receptors in the heart in cardiac disease states is not known. METHODS AND RESULTS: We examined mRNA and protein levels for TNFR1, TNFR2, and TNF-alpha in explanted hearts from organ donors as well as in patients with end-stage dilated cardiomyopathy (DCM) and ischemic heart disease (IHD). Northern blot analysis revealed that mRNA for TNFR1 and TNFR2 was present in nonfailing, DCM, and IHD hearts. TNFR1 and TNFR2 receptor protein levels, as measured by ELISA, were decreased 60% in DCM and IHD patients compared with nonfailing hearts (P < .005). To determine a potential mechanism for the decrease in TNF receptor expression, we measured levels of circulating soluble TNF receptors (sTNFRs) in DCM and IHD patients. This analysis showed that there was a significant one-and-a-half to threefold increase in sTNFRs in DCM (P < .03) and IHD patients (P < .001). Another important finding was that TNF-alpha mRNA and TNF-alpha protein were present in the explanted hearts from DCM and IHD patients but not in nonfailing hearts. CONCLUSIONS: In summary, the results of this study constitute the initial demonstration that TNF receptor proteins are dynamically regulated in patients with advanced congestive heart failure. Moreover, the observation that failing hearts express elevated levels of TNF-alpha suggests that overexpression of this cytokine may be one of several different maladaptive mechanisms responsible for the progressive cardiac decompensation that occurs in advanced heart failure.