Biomedical subjects
Publications and source records attributed to T Takashina.
We reported a case of 51-year-old man with repeated bleeding from gastroesophageal varices and portal vein thrombosis which were successfully treated by transjugular intrahepatic portosystemic shunt (TIPS) and thrombolysis. We used a flexible tip puncture needle (.038") which was thought to be safer than Colapinto needle (16G).
We have successfully developed a new cardiac auscultation simulator by applying recently developed digital and computer technology, which digitally records, stores, modifies, and plays back heart sounds and murmurs characteristic of various heart diseases. The simulator is capable of playing back different heart sounds or murmurs at each auscultatory site (aortic, pulmonic, tricuspid, and mitral) of a human chest-sized mannequin (made of urethane foam), through four built-in speakers. We were able to listen to accurate reproductions of heart sounds and murmurs at the same timing as in real patients by any type of stethoscope used in routine medical practice. This compact and portable educational apparatus, which simulates realistic auscultatory sounds, will impact greatly on the medical training of cardiac auscultation for physicians, medical students, nurses, and paramedicals.
The endodermal layer of the human yolk sac was examined three-dimensionally with light microscopy on serial sections using scanning electron microscopy and transmission electron microscopy to find the origin of hemopoiesis in the yolk sac. Cell-labelling techniques were also employed using the monoclonal anti-transferrin receptor antibody. Orifices of the endodermal and intracellular tubules facing the yolk-sac cavity were demonstrated on the endodermal surface. Various-sized blood cells in various stages of differentiation and maturation were distributed in the yolk-sac cavity and tubules and were observed also at the orifices of the tubules. The morphological and the immunological findings suggest that blood cells with large nuclei in the endodermal layer are the most immature. The present results suggest that blood cells originate from the endodermal layer and are carried to the embryo through the yolk sac cavity and the vitelline duct. It is probable that the endodermal and intracellular systems of tubules have an important role in the transport of blood cells, including stem cells.
In the present study a comparison was made between human yolk sacs and yolk sac tumors. Tubules surrounded by several to as many as 10 endodermal cells and intracellular tubules in one endodermal cell were frequently observed. The tubules were seen abundantly in the yolk sac of a 4-week pregnancy, and they resembled the reticular pattern of the yolk sac tumor. It was also observed that the papillary endoderm, which contained blood cells in the center and protruded into the endodermal tubules, resembled the Schiller-Duval body of yolk sac tumor. Ultrastructurally the tumor cells were similar to the yolk sac endoderm. alpha-Fetoprotein was positive in the yolk sac endoderm until approximately the seventh week of pregnancy. Yolk sac tumor was also alpha-fetoprotein-positive. In other words, our study of human yolk sacs of 4- to 11-week pregnancies presumes that the yolk sac tumor resembles the endoderm of 4- to 7-week pregnancies.
Haemopoiesis in human yolk sacs was examined using tissues obtained from a total of 27 cases in various stages of development from the fourth to eleventh week of pregnancy. In the early stages of development, the yolk sac was observed to be connected to the midgut by the vitelline duct, which became slender with later growth of the embryo. In the early stages of pregnancy, endodermal tissues were found to be a predominant component, whereas in the later stages, the mesenchymal tissues increased. The most immature blood cells and their mitotic figures were observed in the endodermal tissue. Haemopoiesis was found in endodermal tissue before mesenchymal tissue had developed. Electron microscopy revealed that maturation of the blood cells proceeded as the cells were formed in mesenchymal tissue and in blood vessels.
For the purpose of investigating the histogenesis of the yolk sac tumor, 7 cases of the tumor and 9 cases of human yolk sac were used. Histological, ultrastructural investigations together with immunofluorescent antibody examinations revealed the following results. Ultrastructurally yolk sac endodermal cells prior to the 7th week of pregnancy were proved to have microvilli, abundant glycogen which formed rosette, parallel arranged rough endoplasmic reticulum (rER), mitochondria closely associated with rER and ovoid electron dense amorphous granules which showed positive diastase-resistant PAS-reaction. Morphologically endoderm after the 8th week of pregnancy showed degenerative changes. Light microscopically the tumors showed Schiller-Duval body, endodermal sinus structure and clear-cells endoblastic pattern, but ultrastructurally the tumor cells of these three types showed approximately similar appearances. Ultrastructural features of the tumor seem to resemble those of the yolk sac endoderm before the 7th week of pregnancy. The tumor cells which form the epithelial mantling of Schiller-Duval body closely resembled the endodermal cells facing the yolk sac cavity with respect to the presence of abundant glycogen granules, rER, mitochondria, short irregular microvilli on the cell surface and remarkable nucleolus with thread-like nucleolonema. Both the tumor cells facing the endothelial cell and those which form the endodermal sinus structure and clear-cells endoblastic pattern resembled the endodermal cells facing the mesenchyma in view of the features of intracellular organelles, the presence of extracellular basement membrane-like substances and tubular structure.
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