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Biomedical subjects

S Higashi

Publications and source records attributed to S Higashi.

At least 235 records · Page 13Linked to original sources
PubMed1984

In vivo radiolocalization of antiosteogenic sarcoma monoclonal antibodies in osteogenic sarcoma xenografts.

Monoclonal antibodies Ost6 and Ost7 (mouse Immunoglobulin G1) to human osteogenic sarcoma were isolated from ascitic fluid and labeled with radioiodine. After injection into athymic nu/nu mice with s.c. xenografts of human osteogenic sarcoma, the uptake of radioactivity in tumors, visceral organs, and blood was determined. Five days after injection, Ost6 and Ost7 showed preferential accumulation in tumors (tumor:blood ratio, 4.3). Furthermore, with testicular and bladder tumors, both unreactive with Ost7, there was no localization of radiolabeled Ost7 in xenograft growths. When Ost7 was labeled with 131I, its accumulation into human osteogenic sarcoma could be clearly visualized by whole-body gamma-scintigraphy without computer-assisted data processing.

Animals↗
PubMed1984

Endocytotic activity of kitten odontoblasts in early dentinogenesis. 1. Thin section and freeze-fracture study.

The morphological features of odontoblast processes in young kitten odontoblasts were studied by thin section and freeze-fracture electron microscopy. Freeze-fracture replication revealed depressions with particles on the plasma membranes of the proximal parts of odontoblast processes. Comparison with thin sections suggested that these depressions represented sites of endocytosis. Frequent depressions with particles (corresponding to coated pits in thin sections) indicate the high absorptive activity of young odontoblasts. The results indicate that odontoblasts, especially in the proximal parts of their processes, play a significant functional role in the modification of the predentine matrix during early dentinogenesis.

Animals↗
PubMed1983

Fine structure of secretory ameloblasts in kitten tooth germs, with special regard to intercellular junctions as revealed by freeze-fracture.

Using both thin sectioning and freeze-fracture replication, junctional complexes at both proximal and distal ends of the cells consisted of tight junctions in close association with gap junctions and desmosomes. The tight junctions generally consisted of smooth, continuous rows of particles on the P-face and corresponding patterns of shallow grooves on the E-face of cell membranes. Though sealing of paracellular spaces around the ameloblasts in the proximal junctional complex was incomplete, there was complete sealing around the ameloblasts and well-developed meshwork structures of tight junctions in distal junctional complexes. Discontinuous and free-ending strands of tight junctions were frequent in junctional complexes, suggesting that ameloblast distal junctional complexes serve, not only as a barrier to high molecular passive substances through the ameloblast layer, but also as a channel for ions and low-molecular substances. Ameloblasts were firmly connected with stratum intermedium cells by desmosomes and gap junctions. The gap junctions on ameloblast basal and lateral surfaces probably function in intercellular transfer of ions and low-molecular substances between the stratum intermedium and ameloblasts and in control of ameloblast cytodifferentiation.

Ameloblasts↗
PubMed1983

A morphological, tracer and cytochemical study of the role of the papillary layer of the rat-incisor enamel organ during enamel maturation.

Thin-section, freeze-fracture, tracer and cytochemical methods showed that papillary cells were characterized by the presence of numerous mitochondria and microvilli. The cytoplasms contained Golgi apparatus, multivesicular bodies (MVB), tubular structures and coated vesicles. In freeze-fracture replicas, some tubular structures and vesicles were continuous with the cell surfaces. Intravenously-injected horseradish peroxidase (HRP) was rapidly incorporated into the papillary cells via coated vesicles and tubular structures. Horseradish peroxidase-labelled coated vesicles and tubular structures then fused with endocytic vacuoles and MVB. These endocytic vacuoles and MVB showed HRP-labelling of various degrees. Acid-phosphatase activity was demonstrated in the Golgi apparatus, endocytic vacuoles and MVB of papillary cells. Enzymic activity sometimes took place in tubular structures but never occurred in coated vesicles. These results indicate that absorptive and digestive activities of papillary cells are closely related to loss of organic materials from the enamel matrix during enamel maturation.

Acid Phosphatase↗
PubMed1983

Morphology and permeability of junctional complexes in maturing ameloblasts of rat incisors.

Thin sections of newborn rat incisors were examined by tracer experiments and freeze-fracture replication in order to clarify the morphology and permeability of ameloblast junctional complexes in the maturation stage. Ameloblast junctional complexes consisted of gaps and tight junctions at the proximal and distal ends. Whereas the proximal junctional complexes sealed extracellular spaces incompletely, the distal ones formed complete, belt-like barriers around the cell. Tight junctions of these junctional complexes, however, were composed of both continuous and discontinuous rows of particles with various spaces among them. Intravenously injected horseradish peroxidase (HRP) reached the enamel surface through the extracellular spaces among ameloblasts and was absorbed by ameloblasts of the ruffled borders. Pinocytosis and transcellular migration of HRP could not be demonstrated in maturing ameloblasts except in the ruffled border zone.

Ameloblasts↗
PubMed1983

Thin-section, tracer, and freeze-fracture study of the smooth-ended maturation ameloblasts in rat incisors.

The morphology and functional roles of the smooth-ended maturation ameloblasts (SAs) of rat incisors were examined by means of routine thin sections, tracer experiments, and freeze-fracture replication. SAs possessed two sets of junctional complexes consisting of tight junctions (fasiae occludentes) and gap junctions at the proximal and distal ends. Neither the proximal nor the distal junctional complex formed a complete barrier around the cell; intravenously injected horseradish peroxidase (HRP) reached the developing enamel surface through SAs extracellular spaces. SA supranuclear cytoplasm included such various cytoplasmic vesicles as the multivesicular body (MVB), large and vacuoles, dense body, and coated vesicles. The HRP that reached the enamel surface was incorporated into some coated vesicles and small vacuoles via coated pits and membrane invaginations of the distal cell surface of SA. Then, in the process of time, it migrated into the MVB and large endocytic vacuoles. These results indicate that the SA layer forms an extracellular transfer route for metabolites between papillary layer and the enamel surface and that SAs absorb exogenous protein.

Ameloblasts↗
PubMed1982

Stimulated lymphocytes in schizophrenia.

This study examines the effect of neuroleptic medication on the distribution of the reported atypical lymphocytes of schizophrenia. The predominant atypical type in schizophrenia was termed the P-type atypical lymphocyte to differentiate the cell from other types of peripheral lymphocytes. Such P cells showed stimulated features: clear cytoplasmic basophilia and an irregularly shaped nucleus with a leptochromatic structure and occasionally one or two nucleoli, but the cell size ranged from small to large. P cells were found in all 42 schizophrenic patients examined and ranged from 5% to 45% of lymphocytes. Patients receiving neuroleptic medication had a lower mean percentage of P cells (17.8%) compared with patients not receiving neuroleptic medication (28.7%). The findings indicate that neuroleptic medication in not likely to be inducing the P-cell reaction.

Adolescent↗