ilated cardiomyopathy (DCM) is characterized by ventricular dilatation and depressed myocardial contractility, resulting in progressive refractory congestive heart failure and sudden death from ventricular arrhythmias (mainly ventricular tachycardia (VT) and subsequent ventricular fibrillation). 1 A structural increase in ventricular volume (cardiac remodeling) has been viewed as not only an adaptive consequence of initial myocardial damage, but an important determinant of the progression of heart failure. Although risk stratification of cardiac remodeling and ventricular arrhythmias in DCM is an important issue in clinical practice, the factors that lead to cardiac remodeling or induction of VT are not well defined.The adrenergic nervous system, especially through -1-adrenergic receptor ( 1-AR) activation, appears to be of major importance not only in the genesis or progression of cardiac remodeling but also in induction of VT. 2 In transgenic mice, cardiac overexpression of human 1-AR produced an overtly cardiomyopathic phenotype and ultimately chamber dilatation and systolic dysfunction. 3 Clinical evidence has accumulated of the beneficial effect of blockade of 1-AR on cardiac remodeling and prognosis in Circulation Journal Vol.66, August 2002 patients with heart failure caused by DCM or myocardial infarction. 4,5 In the CIBIS-II study, bisoprolol, a highly selective 1-AR blocker, improved the survival rate in patients with heart failure and more importantly, also showed that bisoprolol reduced sudden death most likelycaused by lethal ventricular arrhythmia and hospital admissions for malignant ventricular arrhythmia. 6 The MERIT-HF study showed that metoprolol, a selective 1-AR blocker, also reduced sudden death in patients with heart failure. 7 Accordingly, it seems reasonable to suppose that the signals mediated by 1-AR play an important role in the arrhythmogenesis of heart failure.Beta-1-AR is encoded by a gene comprising a single exon located on chromosome 10q24-26 and consists of 477 amino acids. 8 To date, 18 genetic variants of the single nucleotide chain have been identified. Although 17 of these are located at the coding region, amino acid changes occur only in 7 variants (Ser49Gly, Ala59Ser, Arg389Gly, Arg399Cys, His402Arg, Thr404Ala and Pro418Ala). 9 None of these regions other than the 389 residue have been implicated in the precise function of the 1-AR. The Arg389Gly variant is located at the interface between the last transmembrane helix and the intracellular tail, adjacent to the phosphorylation sites and thought to be critical for Gprotein coupling and subsequent cell signaling. Interestingly, functional studies using transfected fibloblasts indicated that the Arg389 1-AR had approximately 3-fold the adenylyl cyclase activity of the Gly389 1-AR when stimulated by isoproterenol. 10 Therefore, it is quite possible that the Arg389Gly polymorphism functions as either a gene for susceptibility for DCM (role in the emergence of DCM) or a modifier gene (role in the evolution/prognosis Beta-1-ad...

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The polymerization of N-(2,6-dimethylphenyl)itaconimide (1) with azoisobutyronitrile (2) was studied in tetrahydrofuran (THF) kinetically and spectroscopically with the electron spin resonance (ESR) method. The polymerization rate (R,) at 50°C is given by the equation[112, '. The overall activation energy of the polymerization was calculated to be 91 kJ/mol. The number-average molecular weight of poly(1) was in the range of 3 500-6500. From an ESR study, the polymerization system was found to involve ESR-observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (k,) and termination (k,) were determined at 50 "C. k, (24-27 L . mol-' . s-') is almost independent of monomer concentration. On the other hand, k, (3,8. 104-2,0. lo5 L . mol-' . s-') increases with decreasing monomer concentration, which seems mainly responsible for the high dependence of R, on monomer concentration.Thermogravimetric results showed that thermal degradation of poly(1) occurs rapidly at temperatures higher than 360°C and the residue at 500°C was 12% of the initial polymer. For the copolymerization of 1 (MI) with styrene (M2) at 50°C in THF the following copolymerization parameters were found; r , = 0,29, rz = 0,08, Q, = 2,6, and el = +l,l. *) Systematic IUPAC name of itaconic acid methylenesuccimic acid. 0 1991, Hiithig & Wepf Verlag, Base1 CCC 0025-1 16X/91/$05.00