Dissociation between wall thickening of normal myocardium and cyclic variation of backscatter during inotropic stimulation.

The purpose of this study was to determine the relation between increased myocardial wall thickening during inotropic stimulation and quantitative acoustic properties of normal myocardium in humans. We first validated a new 2-dimensional ultrasonic backscatter imaging approach for measurement of cyclic variation in the parasternal long-axis view against conventional M-mode integrated backscatter technique in 41 patients and controls (group A). We then performed 2-dimensional ultrasonic integrated backscatter imaging in 18 patients (group B) with normal segmental function at baseline to determine the magnitude of the cyclic variation of the septum and the posterior wall before and during infusion of dobutamine (10 and 20 microgram/kg/min). Group A patients showed a close correlation of the cyclic variation obtained by the new 2-dimensional ultrasonic integrated backscatter imaging approach and the conventional M-mode technique. Group B patients had mean values of cyclic variation that remained unchanged in the septum (4.4 +/- 1.4, 4.3 +/- 1.7, and 4.8 +/- 1.6 dB at baseline and at each dobutamine stage, respectively, p = NS) and in the posterior wall (6.4 +/- 1.7, 6.4 +/- 1.8 and 6.1 +/- 1.9 dB, respectively, p = NS) despite progressive dobutamine-induced increases in percent wall thickening (septum: 38 +/- 10% to 57 +/- 17% and 68 +/- 19%, respectively, and posterior wall 42 +/- 13% to 72 +/- 20% and 77 +/- 18%, respectively; both p <0.001 vs baseline for both walls). Thus, physical properties of normal myocardium remain unchanged during inotropic stimulation.

Purification and characterization of a mannose/glucose-specific lectin from Vicia cracca.

The seeds of Vicia cracca are known to contain two lectins: an N-acetylgalactosamine-binding lectin, which reacts specifically with human erythrocytes of blood group A, and a mannose/glucose-binding lectin unspecific towards human blood groups. The second lectin is the object of the present work. Purification was achieved by affinity chromatography on Sephadex G-100. The native lectin has a molecular weight of 44,000. It is composed of two small (Mr 5,700) and two large subunits (Mr 17,500). Binding of sugars to the lectin was assayed by equilibrium dialysis and spectrophotometrically; the association constants for glucose are 1.38 X 10(3) l/mol and 2.5 X 10(2) l/mol respectively. The primary structure of the small subunit was determined by analyses of the whole chain, of tryptic and CNBr peptides. It was shown to consist of 53 amino acid residues. The mannose/glucose-binding lectin from Vicia cracca is highly homologous to the lectins from Vicia sativa, Vicia faba, Pisum sativum and Lens culinaris. There is, however, only limited homology of the N-acetylgalactosamine-specific lectin from Vicia cracca.