Biomedical subjects

S Takaichi

Publications and source records attributed to S Takaichi.

58 records · Page 4Linked to original sources

PubMedDate not supplied

Histochemical characterization of low density lipoprotein receptors in internalization-defective familial hypercholesterolemia.

We studied the localization of low density lipoprotein (LDL) bound to the receptors on the cultured fibroblasts from a patient (MN) with homozygous familial hypercholesterolemia and a defect in internalization of LDL and compared the localization with normal fibroblasts and with those from another internalization-defective cell, GM2408A. Monolayers of cells were cultured with lipoprotein-deficient human serum, and the cells were incubated with 125I- or ferritin-labeled LDL. The LDL binding was observed by autoradiography or by an electron microscope. Autoradiographs of bound 125I-LDL confirmed that MN's cells could not internalize LDL inside the cell at 37 degrees C. In these cells, ferritin LDL was found mainly in noncoated regions at 4 degrees C; it was not found in endocytic vesicles after incubation at 37 degrees C. Ferritin cores that bound on the surface of the cells from the normal subject, from GM2408A, from MN, and from MN's parents, were counted and quantitatively analyzed at 4 degrees C. In normal cells, 62% of the ferritin cores were bound in the coated pits; in MN's cells, only 11% of the ferritin LDL was found in the coated pits; in the GM2408A cells, 12% of the ferritin LDL was found in the coated pits; in the cells from MN's parents, 40% of the ferritin LDL was found on the coated pits. The results indicate that the internalization defect in MN's cells is the same as that in the GM2408A cells; neither can localize the LDL and LDL receptor complex in coated pits.

Cells, Cultured↗

PubMedDate not supplied

Cardiac disuse atrophy during LVAD pumping.

The authors investigated morphologic changes of myocardial tissue of goats supported with a long-duration left ventricular assist device (LVAD). The bypass flow rates of the LVAD were kept at maximum levels (about 80% of total cardiac output) in four goats for 30 days, and at a limited flow rate (around 60%) in one goat each for 30 and 90 days. Morphometric studies using light and electron microscopy were performed on the left ventricles, comparing them to those in the four control studies. The results disclosed: 1) relative volume densities of the myocytes and interstitial tissue in the myocardium were unchanged; 2) cross-sectional areas of the myocytes in the maximum bypass cases were significantly reduced in comparison with pre-experimental data; 3) relative myocyte volumes, calculated by myocytes and nuclear volume densities, were reduced in three goats in the maximum bypass group; and 4) relative volume density of myofibrils was reduced in the maximum and 90 day bypass groups, whereas that of mitochondria was reduced only in the 90 day bypass case. These results indicate that LVADs cause cardiac atrophy which correlates with bypass flow rate and duration of assistance.

Animals↗

PubMedDate not supplied

A synthetic tetrapeptide as a novel platelet-preserving agent during cardiopulmonary bypass.

The possibility of using the synthetic tetrapeptide arginine-glycine-aspartic acid-serine (Arg-Gly-Asp-Ser, RGDS), which was recently identified as the common cell attachment site of adhesive plasma proteins, for platelet preservation during cardiopulmonary bypass (CPB) was investigated. The synthetic RGDS inhibited platelet aggregation and adhesion and secretion of thromboxane A2 in a dose-dependent manner, due to antagonistic inhibition via ligand-receptor interaction. Platelet consumption during CPB was drastically reduced by the administration of RGDS with no remarkable change in hemodynamics and a fairly rapid recovery of platelet functions. Electron microscopic observation revealed that this platelet-preserving effect of RGDS resulted from the inhibition of adhesion and aggregation on the artificial surface. These strongly indicate that the cell attachment site of adhesive plasma proteins plays an important role in platelet consumption during CPB. The synthetic RGDS acting as an antagonist of the platelet membrane receptor, is a novel platelet-preserving agent, especially useful when using an extracorporeal circuit with a large blood-material contact area, such as CPB.

Animals↗

PubMedDate not supplied

Morphologic changes of the aortic wall due to reduced systemic pulse pressure in prolonged non pulsatile left heart bypass.

The morphologic changes of the aortic wall due to reduced systemic pulse pressure in prolonged non pulsatile left heart bypass (LHB) were investigated. Sixteen adult goats were divided into three groups: the non pulsatile group in which non pulsatile LHB was conducted for 137 days on average, the pulsatile group in which pulsatile LHB was conducted for 79 days on average, and the control group used as the normal control. The average aortic pulse pressures were 12, 48, and 37 mmHg, respectively. At the end of the experiments, the descending aorta was excised and subjected to morphologic examination. The wall thickness of the aorta in the non pulsatile group (1.4 mm) was significantly thinner than that in the pulsatile group (2.2 mm) and the control group (2.0 mm), and the volume ratio of smooth muscle cells (SMC) in the non pulsatile group (37%) was lower than that in the pulsatile group (48%) and the control group (49%). In SMC classification, the proportion of SMC with low activity and low contractility in the non pulsatile group (57%) was high as compared with that in the pulsatile (2%) and control (5%) groups. These results strongly indicate that prolonged non pulsatile LHB causes substantial morphologic changes in the aorta.

Animals↗