Indicial functions of arterial remodeling in response to locally altered blood pressure

We investigated the effect of locally altered blood pressure on the remodeling processes of the cells and extracellular matrices of the splenic and ileal arteries and used an indicial function approach to quantitatively analyze the relationship between the altered blood pressure and the remodeling processes. Blood pressure in these arteries was locally modulated by constricting the aorta at a location between the celiac and mesenteric bifurcations, resulting in a higher blood pressure at the splenic arteries then at the ileal arteries, After the pressure changes, the cross-sectional areas and the fractions of the cells and extracellular matrices of the splenic and ileal arteries were examined by electron microscopy at 2, 6, 10, 20, and 30 days. We found that both arteries remodeled, but the splenic arteries (higher blood pressure) remodeled more rapidly and to a larger degree than the ileal arteries (lower pressure compared with the splenic arteries) of the same animal. To verify whether an identical change in the blood pressure at the splenic and ileal arteries leads to the same remodeling process in these arteries, we created another model by constricting the aorta at a location between the mesenteric and renal bifurcations, resulting in hypertension of the same level at both splenic and ileal arteries. We found that the remodeling processes of the cells and matrices were almost identical in the arteries with similar changes in blood pressure. Thus we conclude that the remodeling processes of cells and matrices of the splenic and ileal arteries are dependent on the local blood pressure in aorta constriction-induced hypertension, and the indicial analysis is a useful approach in the description of the relationship between the blood pressure and the arterial remodeling processes.

Sorting of endocytosed transferrin and asialoglycoprotein occurs immediately after internalization in HepG2 cells.

After receptor-mediated uptake, asialoglycoproteins are routed to lysosomes, while transferrin is returned to the medium as apotransferrin. This sorting process was analyzed using 3,3'-diaminobenzidine (DAB) cytochemistry, followed by Percoll density gradient cell fractionation. A conjugate of asialoorosomucoid (ASOR) and horseradish peroxidase (HRP) was used as a ligand for the asialoglycoprotein receptor. Cells were incubated at 0 degree C in the presence of both 131I-transferrin and 125I-ASOR/HRP. Endocytosis of prebound 125I-ASOR/HRP and 131I-transferrin was monitored by cell fractionation on Percoll density gradients. Incubation of the cell homogenate in the presence of DAB and H2O2 before cell fractionation gave rise to a density shift of 125I-ASOR/HRP-containing vesicles due to HRP-catalyzed DAB polymerization. An identical change in density for 125I-transferrin and 125I-ASOR/HRP, induced by DAB cytochemistry, is taken as evidence for the concomitant presence of both ligands in the same compartment. At 37 degrees C, sorting of the two ligands occurred with a half-time of approximately 2 min, and was nearly completed within 10 min. The 125I-ASOR/HRP-induced shift of 131I-transferrin was completely dependent on the receptor-mediated uptake of 125I-ASOR/HRP in the same compartment. In the presence of a weak base (0.3 mM primaquine), the recycling of transferrin receptors was blocked. The cell surface transferrin receptor population was decreased within 6 min to 15% of its original size. DAB cytochemistry showed that sorting between endocytosed 131I-transferrin and 125I-ASOR/HRP was also blocked in the presence of primaquine. These results indicate that transferrin and asialoglycoprotein are taken up via the same compartments and that segregation of the transferrin-receptor complex and asialoglycoprotein occurs very efficiently soon after uptake.

Signal-to-noise ratio and spectra of explosion-generated Rayleigh waves

abstract This preliminary theoretical study is basically concerned with the estimation of the depth of an explosive source from a knowledge of the radiated Rayleigh wave. Details are given of the dependence of the amplitude spectrum on the explosive yield, depth of burial, horizontal range, and the elastic parameters of the medium. It is assumed that the medium is a homogeneous and isotropic half space which, as far as the Rayleigh wave is concerned, possesses a mechanical quality factor, or Q, which is independent of frequency. Furthermore, it is assumed that the explosive shot has been effectively decoupled from the medium by locating it within a cavity of appropriate size. It is shown that changes in either shot depth or Q can produce an identical change in the Rayleigh wave spectrum. Hence a lack of knowledge of Q limits the accuracy with which source depth may be estimated. An additional inaccuracy may result from the ambient ground motion preventing the recovery of the Rayleigh wave spectrum. For this reason estimates are given of the theoretically anticipated Rayleigh signal-to-noise ratio per kiloton of explosive in a seismically quiet location. It is emphasized that the study is preliminary in nature. To be of significant practical use it is believed that the theory must be extended to take into account the effect of surface layering of the medium.