Biomedical subjects
M Morishima
Publications and source records attributed to M Morishima.
Radiology rounds: interventional radiology.
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Radiology rounds: the injured ankle.
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Posttranslational modifications of tau in paired helical filaments.
Paired helical filaments (PHF) are fibrillar structures that accumulate in degenerating neurons of AD brain. We have purified their components, PHF-tau and PHF-smear, and analyzed them protein chemically. PHF-tau is abnormally phosphorylated. Although the characteristic of this phosphorylation is similar to that of fetal tau, its extent is higher in PHF-tau. The additional phosphorylation in PHF-tau may cause its loss of microtubule assembly capacity. Our results on the phosphorylation sites suggested that fetal tau and presumably PHF-tau are in vivo substrates of proline-directed protein kinases. PHF-smear consisted largely of the carboxyl-terminal portion of tau and ubiquitin. The ubiquitin-targeted protein was identified as tau in PHF and the conjugation sites were localized to the microtubule-binding region. It is most likely that abnormally phosphorylated full-length tau (PHF-tau) accumulates as PHF, which is then gradually processed from its amino-terminus and followed by ubiquitination.
Neointima formation on an antithrombogenic cardiac wall substitute that can be reconstructed by host cells.
The authors previously reported on a new cardiac wall substitute (collagen-coated ultrafine polyester mesh, CUFP), which in an animal study showed satisfactory antithrombogenicity due to its hydrophilicity and excellent neointimal formation because it induced cell migration and proliferation. Both the ultrafine polyester mesh, and the collagen cross-linked with a hydrophilic reagent, have a special affinity for host cells. In the current study, the focus was on neointima formation on the CUFP, compared with that on glutaraldehyde-treated equine pericardium (GA graft), over longer time periods. Twenty-one CUFPs, and 19 GA grafts as controls, were implanted as patches in the right ventricular outflow tract in 40 dogs. In the CUFP at 28 days, a thin neointima, which was almost endothelialized, had been formed. Fibroblasts and vasa vasorum were seen inside both the neointima and the graft wall. The CUFP showed a white, shiny, smooth, thin, and uniform neointima with endothilialization at 486 days, and the neointima was firmly anchored by day 699. In the GA graft at 484 days, however, the neointima was partly detached from the GA graft and almost no fibroblasts had infiltrated the graft wall. Therefore, neointimal formation on the CUFP is almost completed within 1 month and maintained over the long term.
A new bioprosthetic cardiac valve with reduced calcification.
A bioprosthetic cardiac valve cross-linked with a glycerol polyglycidyl ether polyepoxy compound (PC) was developed in order to reduce calcification and degeneration, which often occurs in bioprosthetic cardiac valves. Aortic valves harvested from dogs were treated with PC (PC valve). Right ventricle (RV)-pulmonary artery (PA) bypasses were placed in 12 dogs with PC-valved conduits, and the main PA was ligated. X-ray right ventriculography at 36 days (1 dog) and 37 days (1 dog) revealed an excellent open/close performance of the PC valve, and there was no visible thrombus in the valve. In our basic study, PC treated collagen gel disks implanted in the subcutaneous layer of growing rats showed remarkably less calcium deposition than did those treated with glutaraldehyde (GA). Biologic materials cross-linked with PC maintain their pliability, and become more hydrophilic and more hydrated than those cross-linked with GA. The hydrophilicity and hydration provide sufficient antithrombogenicity and a suitable environment for metabolism in the tissue fluid which contains oxygen, nutritive substances, and electrolytes, leading to inhibition of material degeneration. Therefore, PC valves are expected to show good valve function, sufficient antithrombogenicity, and excellent durability with less calcification, when compared to GA treated valves.
Development of an antithrombogenic cardiac wall substitute which can be reconstructed by infiltration of host cells.
Various kinds of materials, such as glutaraldehyde-treated pericardial heterografts, have been used as a cardiac wall substitute. Some problems were encountered with their use. We clarified these problems in animal experiments and developed a new cardiac wall substitute to overcome them. As one of the best cardiac wall substitutes obtainable at present, glutaraldehyde-treated equine pericardium (Xenomedica, GA-graft), was sutured as a patch in the right ventricular outflow tract (Group 1: 16 dogs). A new cardiac wall substitute, which is composed of collagen-coated polyester mesh (CUFP), was sutured in the same fashion (Group 2: 19 dogs). The problems clarified in the GA graft were insufficient antithrombogenicity and poor healing of the neointima and the graft wall. The CUFP had sufficient antithrombogenicity and good healing quality as a cardiac wall substitute. CUFP should be rapidly infiltrated by host cells, to become a kind of host organ and therefore not degenerate with long-term use.
The unilateral hyperlucent lung.
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