Jun-ichi Sanada

Isovolumetric relaxation flow in patients with ischemic heart disease

OBJECTIVES The purpose of this study was to clarify the characteristics of flow during the isovolumetric relaxation period and to analyze the relation between these flow patterns and standard hemodynamic indexes. BACKGROUND Outward motion of the left ventricle during the isovolumetric relaxation period has been observed by cineangiography. However, there is little information about blood flow during this period. METHODS Seventy-nine patients with ischemic heart disease were examined by pulsed Doppler echocardiography and cardiac catheterization. All patients were classified into three groups according to the observed patterns of isovolumetric relaxation flow: group I (n = 41), flow directed toward the apex; group II (n = 21), flow directed toward the base, and group III (n = 17), low velocity flow (< 12 cm/s) without a dominant direction. Patients in group I were further classified into group Ia (n = 19) with normal ventriculograms and group Ib (n = 22) with asynergy. RESULTS Left ventricular ejection fraction and negative first derivative of left ventricular pressure were significantly lower in group II (49 +/- 9% and 1,274 +/- 212 mm Hg/s, respectively) and group III (38 +/- 8% and 1,147 +/- 280 mm Hg/s, respectively) than in group Ia (68 +/- 7% and 1,727 +/- 358 mm Hg/s), each p < 0.01. Time constant was significantly prolonged in group II (49 +/- 6 ms) and group III (48 +/- 6 ms) compared with that in group Ia (41 +/- 6 ms), p < 0.05. On left ventriculography, patterns of outward wall motion during the isovolumetric relaxation period were associated with the patterns of isovolumetric relaxation flow. CONCLUSIONS Changes in left ventricular relaxation are accompanied by alterations in isovolumetric relaxation flow. It is therefore useful to evaluate isovolumetric relaxation flow when investigating early diastolic ventricular function.

HEPARIN BINDING PROTEIN-44 (HBP-44)/RECEPTOR-ASSOCIATED PROTEIN (RAP) MEDIATES CELL-SUBSTRATUM ADHESION OF MOUSE NIH/3T3 CELLS THROUGH ITS BINDING TO LOW DENSITY LIPOPROTEIN (LDL) RECEPTOR-RELATED PROTEIN (LRP)

The low density lipoprotein receptor-related protein (LRP) is a multifunctional endocytic receptor with the ability to bind and endocytose several structurally and functionally distinct ligands. The 39 kDa receptor-associated protein (RAP) is an endoplasmic reticulum (ER) resident protein, which is believed to function intracellularly as a molecular chaperone for LRP and to regulate its ligand binding activity along the secretory pathway. Mouse heparin binding protein-44 (HBP-44) is a homologue of human RAP. Using a recombinant form of HBP-44 expressed in Escherichia coli cells as a highly specific ligand for LRP, we demonstrated that HBP-44 coated on cell culture plates mediates the cell-substratum adhesion of mouse 3T3 fibroblasts in a dose-dependent manner, with 50% attachment at the concentration of 0.2 micrograms/ml. Ligand blot analysis with HBP-44 of whole cell extracts and the materials precipitated by anti-LRP antibodies revealed that the receptor for HBP-44 on NIH/3T3 cells was LRP. The results suggest that LRP serves as a cell adhesion receptor in some cells.