RESUMO
Thyroid hormone (TH) is critical in cardiac cell differentiation (regulating contractile proteins and cell geometry) and this effect could be potentially exploited therapeutically in reversing the process of de-differentiation which underlies postischemic cardiac remodeling. Acute myocardial infarction was induced in male Wistar rats by ligating left coronary artery (AMI, n=8), while sham operated animals served as control (SHAM, n=8). 13 weeks after AMI, TH was administered in a group of animals for 4 weeks (AMI-THYR, n=9). TH significantly increased beta-MHC and decreased alpha-MHC expression in the myocardium. This response was accompanied by changes in cardiac geometry: sphericity index, (SI, long to short axis ratio) was found to be 1.95 (SEM, 0.02) in SHAM, 1.51(0.03) in AMI and 1.64(0.03) in AMI-THYR, p<0.05. As a consequence, cardiac function was significantly improved: left ventricular ejection fraction (EF%) was 74.5% (SEM, 2.8) in SHAM vs 29.5% (2.1) in AMI, and 40.0% in AMI-THYR, p<0.05. Furthermore, +dp/dt and -dp/dt were 4250 (127) and 2278 (55) in SHAM vs 2737(233) and 1508 (95) in AMI vs 3866 (310) and 2137(111) in AMI -THYR, respectively, p<0.05. TH treatment partially reverses cardiac dysfunction in rats with old myocardial infarction by favorably changing cardiac chamber geometry and expression of myosin isoforms. Thyroid hormone, unlike current treatments, appears to be a paradigm of therapeutic intervention which aims at restoring cardiac geometry and may prove new effective treatment for heart failure.
Assuntos
Infarto do Miocárdio/tratamento farmacológico , Miocárdio/patologia , Hormônios Tireóideos/fisiologia , Hormônios Tireóideos/uso terapêutico , Remodelação Ventricular/efeitos dos fármacos , Animais , Ecocardiografia , Insuficiência Cardíaca/prevenção & controle , Masculino , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/fisiopatologia , Miocárdio/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Isoformas de Proteínas , Ratos , Ratos Wistar , Hormônios Tireóideos/administração & dosagem , Hormônios Tireóideos/farmacocinética , Fatores de TempoRESUMO
We present a retrospective epidemiological study based on 1061 patients admitted to our burns centre in Greece over the 5-yr period from January 2002 to January 2007. Their average age was 25 yr, and 61% were female. The two main causes of burns were scalding and flames. Other significant causes were chemicals and friction. Electricity, frostbite, and contact burns were less frequent. The upper extremity and face were most commonly affected, followed by the lower limbs. All the patients had minor burns (less than 20% total body surface) and were treated on an out-patient basis as there was no need for hospitalization.
