Dominant inhibition of thyroid hormone action selectively in the pituitary of thyroid hormone receptor-beta null mice abolishes the regulation of thyrotropin by thyroid hormone.

Thyroid hormones, T4 and T3, regulate their own production by feedback inhibition of TSH and TRH synthesis in the pituitary and hypothalamus when T3 binds to thyroid hormone receptors (TRs) that interact with the promoters of the genes for the TSH subunit and TRH. All TR isoforms are believed to be involved in the regulation of this endocrine axis, as evidenced by the massive dysregulation of TSH production in mice lacking all TR isoforms. However, the relative contributions of TR isoforms in the pituitary vs.

Effects of chronic cardiomyoplasty on ventricular remodeling in a goat model of chronic cardiac dilatation: part 2.

Background: Reduction of ventricular dilatation, rather than direct improvement of pump function, has been suggested to be the main working mechanism of dynamic cardiomyoplasty (CMP). This working mechanism was examined in the goat using a chronic cardiac dilatation model induced by the creation of a cervical arteriovenous shunt and submitted to passive and active CMP.

Methods: Fourteen female goats underwent surgical creation of a shunt between the left carotid artery and the jugular vein.

Effects of acute dynamic cardiomyoplasty in a goat model of chronic ventricular dilatation: part 1.

Background: The acute effects of cardiomyoplasty in an experimental model of chronic dilated heart have not been thoroughly investigated. Therefore, a model of chronic left ventricular (LV) dilatation was created to accurately determine actual changes shortly after passive and active wrapped skeletal muscle.

Methods: A carotid-jugular shunt model in 8 goats was used to induce progressive dilatation of the cardiac ventricles.

Perioperative hemodynamic and geometric changes of the left ventricle during cardiomyoplasty in goats with dilated left ventricle.

Objective: Clinical data have suggested the occurrence of temporary short-term deterioration of the heart following cardiomyoplasty. The purpose of this study was to monitor the short-term hemodynamic effects of cardiomyoplasty in a goat model of a dilated left ventricle, using conductance catheters (ie, pressure-volume loops) and cardiac output measurements.

Methods: Eight female goats underwent acute cardiomyoplasty 8 to 12 weeks after left ventricular (LV) dilatation was induced by a carotid jugular arteriovenous shunt.

Type 2 iodothyronin deiodinase transgene expression in the mouse heart causes cardiac-specific thyrotoxicosis.

Type 2 iodothyronine deiodinase (D(2)) catalyzes intracellular 3, 5, 3' triiodothyronine (T(3)) production from thyroxine (T(4)), and its messenger RNA mRNA is highly expressed in human, but not rodent, myocardium. The goal of this study was to identify the effects of D(2) expression in the mouse myocardium on cardiac function and gene expression. We prepared transgenic (TG) mice in which human D(2) expression was driven by the alpha-MHC promoter.