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Biomedical subjects

F Suzuki

Publications and source records attributed to F Suzuki.

At least 631 records · Page 35Linked to original sources
PubMed1977

Sertoli cell junctions in the germ cell-free testis of the congenic mouse.

Intercellular junctions between the Sertoli cells in the germ cell-free testis of the congenic mouse were studied during ontogeny. In freeze-fracture replicas, these junctions are characterized by a great number of parallel occluding junctions, in which the particles are preferentially located in the center of the grooves in the E face. These particles appear to be arranged in discrete rows in both P and E fracture faces. In the initial stages of junction formation, large gap junctions with hexagonally packed particle aggregates and particle-free regions are observed. In the later stages, short segments of the occluding junctions are found associated with gap junctions. In later stages, the gap junctions diminish in size and number. These junctions are quite similar to those between Sertoli cells in the normal mouse and rat reported previously. The Sertoli cell junctions develop in the absence of the spermatogenic cells of this congenic mouse.

Age Factors↗
PubMed1976

Freeze-fracture observations on the intercellular junctions of Sertoli cells and of Leydig cells in the human testis.

Normal and feminized human testes were examined by means of freeze-fracture. In both cases, the junctional complexes between adjacent Sertoli cells show a unique characteristic feature. Many parallel linear occluding junctions are located circumferentially around the cell surface at the level of the nucleus. They are more than forty in number over one Sertoli cell surface. In the A face, the particles are not prominent on the ridge of the junctions. Instead, they are clearly seen in the center of the groove of the junctions on the B face. Gap junctions consisting of particle aggregation are not found between the Sertoli cells. The gap junctions between the Leydig cells are frequently observed in both normal and feminized testes. They are round or elliptic in contour and about several micrometers in diameter. The particles, about 8 nm in diameter, are closely packed to form a quasi-hexagonal pattern. The pits are found on the B face corresponding to the particle aggregation.

Adult↗
PubMed1976

The postnatal development of the junctional complexes of the mouse Sertoli cells as revealed by freeze-fracture.

Mouse testes of newborn to adult were examined by freeze-fracture. Between the newborn Sertoli cells, gap junctions consisting of aggregations of the intramembranous particles (about 8 nm in diameter) are frequently found. Some of the junctions are about 1 mum in diameter and show particle-free regions in the aggregation. Linear arrangements of a few particles, which appear to be the initial formation of the occluding junctions, are seen in the newborn sertoli cells. The occluding junctions are arranged in a meshwork, in which the gap junctions are situated between the stages of newborn to six days of age. The particles of the occluding junctions are predominantly located on the B face in the center of the groove instead of the A face of the ridge. The occluding junctions do not appear to surround the entire circumference of the Sertoli cell of the 6-day-old mouse. The gap junctions decrease in size. In later stages, many parallel occluding junctions (up to forty in number) are found over one Sertoli cell surface and are distributed circumferentially around the entire cell surface, indicating establishment of the blood-testis barrier. The occluding junctions dominate and the gap junctions diminish in number as development proceeds.

Animals↗
PubMed1976

Linkages in thermal copolymers of lysine.

The thermal copolymerization of lysine with other alpha-amino acids has been studied further. The identity of the second amino acid influences various properties of the polymer obtained, including the proportion of alpha and epsilon linkages of lysine. A review of linkages in proteinoids indicated alpha and beta linkages for aspartic acid, alpha and gamma linkages for glutamic acid, alpha and epsilon linkages for lysine, and alpha linkages for other amino acids. Thermal proteinoids are thus more complex in types of linkage than are proteins.

Amino Acids↗
PubMed1976

Antiviral and interferon-inducing activity of a new glutarimide antibiotic, 9-methylstreptimidone.

The antiviral effect of 9-methylstreptimidone (9-MS) was examined in mice infected with mouse-adapted influenza A(2) (H(2)N(2)) virus. Both a single and continuous prophylactic administration of 9-MS protected mice from virus infection, and comparison between the minimal effective and the 50% lethal dose gave a therapeutic index of 60. When the treatment was started after infection, however, no antiviral effect was demonstrated. After a single intraperitoneal administration of 9-MS, a highly potent virus-inhibitory factor was detected in the lungs (10 h later) and the sera (16 h later) of uninfected mice, which was assumed to be an interferon on the basis of the biological characteristics. These results suggest that the protective activity of the antibiotic is due to interferon induction in mice.

Animals↗
PubMed1976

Fine structural changes in the epididymal epithelium of moles (Talpa europaea) throughout the year.

The epididymis of the European mole (Talpa europaea) was studied by light and electron microscopy. In the sexually active animal, spermatozoa mature during their passage through the epididymis and the structure of the cells lining the duct suggests a clear regional division into initial, middle and terminal segments. Numerous intra-epithelial vesicles were present in the distal part of the middle segment of sexually active moles and the lining epithelium in the terminal segment appeared to be secretory. Variation in the sensitivity of different regions of the epididymis to androgens was apparent: the principal cells of the initial segment were morphologically active only during the peak of the breeding season in spring, while the cells of the terminal segment became active earlier and remained so for longer. During sexual regression, many autophagic vacuoles were found in the principal cells, and these became transformed into lipofuscin pigment granules. Cells heavily laden with these granules appeared concurrently in the lining epithelium. It is suggested that such cells may be involved in the regression of principal cells by means of heterophagic activity. A similar situation was also observed, but to a lesser extent, at the beginning of the breeding season. Outside the breeding season, the organelles of the principal cells were poorly developed throughout the epididymis, and lipofuscin pigment granules remained in the principal and basal cells of adults. Such granules were seldom seen in immature animals.

Animals↗
PubMed1975

Osteogenesis by chondrocytes from growth cartilage of rat rib.

Chondrocytes were isolated from growth and resting cartilage of rat rib and cultivated in vitro. The cultivated chondrocytes were placed in Millipore diffusion chambers, which were then implanted into the abdominal cavities of rats for several weeks and prepared for histological analysis. The results indicate that growth cartilage cells have a remarkable osteogenic potential, even after cultivation in vitro, whereas resting cartilage cells show no osteogenic activity. However, growth cartilage cells alone do not form new bone but require the participation of certain host cells to initiate osteogenic differentiation.

Cartilage↗
PubMed1975

Microtubules with 15 subunits in cockroach epidermal cells.

Since Ledbetter and Porter (1964) described the 13 subunits which are visible in cross sections of negatively stained plant microtubules, subsequent observations have generally confirmed this number. By using Mizuhira's fixative composed of tannic acid and glutaraldehyde, it is easyto demonstrate the subunits of microtublules without optical reinforcement Cytoplasmic microtubules and sperm axonemes, fixed with Mizuhira's fixtive, similarly show 13 subunits (Mizuhira's and Futaesaku, 1971, 1972; Futaesaky et al., 1972; Tilney et al., 1973). This paper will describe a particular type of microtubule in insect epidermal cells fixed with the above fixative. The number of the subunits is found to be 15 in tranverse sections.

Animals↗
PubMed1975

Experimental evaluation of some controversial points regarding the A-V conduction disturbances in the clinical His bundle electrogram.

Although the recordings of the His potential have been shown to be very useful in the study of cardiac conduction and rhythm disturbances, there remain some problems regarding the clinical His bundle electrogram. Some of the studies were performed to solve in the perfused dog hearts and in situ dog hearts, and consequently the following results were obtained. In some experiments, recording of the His potential could not be achieved even in the perfused hearts in spite of the preserved A-V conduction, suggesting that, as experienced sometimes in the clinical cases, inability to record the His potential might not be due to the technical failure or the anatomical abnormalities of the His bundle. On the other hand, real "splitting of H" occurred in association with the increase in the duration and decrease in the amplitude of the His potential after the ligation of the anterior septal artery. In addition, the true Mobitz II type A-H block, and Wenckebach type intra-Hisian and H-V block could be produced experimentally.

Animals↗
PubMed1975

Effect of the interferon inducer, dextran phosphate, on influenza virus infection in mice.

Intraperitoneal administration of dextran phosphate (MW 40,000) or DP 40, an interferon inducer, was shown to increase the survival rate of mice infected with 10 LD50 dose of influenza A2 virus (H2N2). In the treated mice, a 1-day delay was evident in the virus growth in lung, and production of HAI antibody, when compared to the nontreated or dextran-treated controls. More significant was the 2-day delay in the development of lung consolidation, which leads to 40% survival of the treated mice. Mediation of the protection by the interferon induced by DP 40 was indicated.

Animals↗