Abnormal cardiac wall motion and early matrix metalloproteinase activity.

Activation of matrix metalloproteinases (MMPs) in the heart is known to facilitate cardiac remodeling and progression to failure. We hypothesized that regional dyskinetic wall motion of the left ventricle would stimulate activation of MMPs. Abnormal wall motion at a target site on the anterior lateral wall of the left ventricle was induced by pacing atrial and ventricular sites of five open-chest anesthetized dogs.

Transmural distribution of three-dimensional systolic strains in stunned myocardium.

Background: Regional function in stunned myocardium is usually thought to be more depressed in the endocardium than the epicardium. This has been attributed to the greater loss of blood flow at the endocardium during ischemia.

Methods And Results: We measured transmural distributions of 3D systolic strains relative to local myofiber axes in open-chest anesthetized dogs before 15 minutes of left anterior descending coronary artery occlusion and during 2 hours of reperfusion.

Flow-function relations during graded coronary occlusions in the dog: effects of transmural location and segment orientation.

Objective: The sensitive relationship between regional myocardial perfusion and local systolic deformation during acute myocardial ischemia is not independent of the transmural location or segment orientation. The aim of this study was to determine the effects of fiber orientation and transmural location on the relationships between regional myocardial flow and three-dimensional systolic wall strain during graded coronary artery occlusions.

Methods: Transmural distributions of three-dimensional strain (by biplane radiography of implanted radiopaque markers) and myocardial blood flows (using fluorescent microspheres) were measured in the ischemic region during graded left anterior descending (LAD) coronary artery occlusions in 12 anesthetized dogs.

Distributed mechanics of the canine right ventricle: effects of varying preload.

Fundamental questions in the mechanics of the right ventricle (RV) include: what are the distributions of diastolic and systolic strains across the RV epicardium and how do these strains change with increasing preload? Arrays (approximately 4 x 4 cm) of 25 to 30 lead markers were sutured to the epicardium of the RV anterior free wall in 6 open-chest, anesthetized dogs. Biplane cinéradiography (16 mm, 120 fps) was used to track marker positions throughout the cardiac cycle as loading conditions were altered by intravenous volume infusion. Continuous two-dimensional nonhomogeneous deformations were estimated across the region by fitting high-order finite element surfaces to the three-dimensional marker coordinates in successive ciné frames.

Tgf-Beta promotes the growth of bovine chondrocytes in monolayer culture and the formation of cartilage tissue on three-dimensional scaffolds.

We have investigated the ability of transforming growth factor beta (TGF-beta) to promote the growth and differentiation of chondrocytes in monolayer and on three-dimensional scaffolds. Treatment of chondrocytes with TGF-beta and ascorbate individually stimulated the proliferation of bovine articular chondrocytes about 2-fold when cells were grown in monolayer culture: the combination of TGF-beta and ascorbate resulted in a 3-fold increase in cell number over a 72-h period. Peak stimulation with TGF-beta occurred at about 1.