PubMed Health⌕ Search

Biomedical subjects

H Takahama

Publications and source records attributed to H Takahama.

33 records · Page 2Linked to original sources
PubMed1988

Cytochemical studies of hydrogen peroxide production in the tadpole tail of Rana japonica during metamorphic climax.

The degeneration of tadpole tail tissue was investigated cytochemically by localizing the sites of hydrogen peroxide production. A cerium perhydroxide precipitation method was used. No reaction product was found in resting macrophages and intact muscle fibres during premetamorphosis. In the metamorphosis phase, extensive cerium precipitates were visualized on the outer surface of the plasma membrane of phagocytotic macrophages, fibroblasts, neutrophils, epidermal cells, muscle fibres, notochordal cells, nerve cells and capillary endothelial cells. The reaction products were localized on those parts of the plasma membranes of the macrophages that were in contact with those of adjoining cells. When catalase were added, the amount of deposits decreased. alpha-Tocopherol and indomethacin, but not dexamethasone, significantly inhibited the formation of the reaction products. These findings are taken to indicate that active oxygen is produced on the plasma membrane of activated macrophages and may play a role in the degeneration of the tail tissue.

Animals↗
PubMed1988

[Clinical study of primary pontine hemorrhage].

Forty-three cases of primary pontine hemorrhage were seen in our hospital from 1979 to 1986. We studied the correlations between clinical signs, CT, ABR findings and their outcomes, and then reported surgical results. The case consisted of 30 males and 13 females between 32 to 73 years with an average age of 54.5. Thirty cases were confirmed to have had hypertension prior to the hemorrhage. In ten other cases hypertension was suspected, although their past histories were not obtained. In the remaining three cases, no hypertension was detected. On admission, comatose state, ocular fixation, absence of light reaction, tetraplegia, decerebrate posture, respiratory disturbance, tachycardia and hyperthermia were the signs of unlikely recovery. On the CT, the hematomas of the group of likely recovery patients were less than 25% of the cross section of the pons and lower midbrain in vertical. Greater size of hematomas were seen exclusively among the groups of death and severe disability cases. Acute stage ABR and CT findings showed discrepancy. We suggest, if ABR, CT findings and clinical symptoms were studied more in depth, it is possible to determine a patient's prognosis more precisely. Three cases were treated by Stereotactic Aspiration, three cases by ventricular drainage and the remaining thirty-seven cases conservatively. There was, however, no significant difference in recovery between surgically treated cases and conservatively treated one. We think that surgical indication is doubtful except for limited cases.

Adult↗
PubMed1985

Network and lamellar structures in the tail muscle fibers of the metamorphosing anuran tadpole.

Networks of regularly arranged tubular units and lamellar structures were observed in the degenerating tail muscle fibers of spontaneously metamorphosing anuran tadpoles. These networks appeared to be similar to those previously found in the skeletal muscle of other animals under abnormal conditions. They stained clearly with ruthenium red (RR) and a continuity with the transverse tubular system (T tubules) of triads was clearly observed. The diameter of the tubular unit, 20-25 nm, was almost equal to that of the T tubules of the intact tail muscle fibers, indicating the network structures were probably formed by T tubules connecting together. In the early stages of metamorphosis, networks in the tetragonal configuration were observed within the end region of the muscle fibers. At the climax of metamorphosis, well-developed networks in which the tubular units were arranged in a hexagonal pattern were seen in various regions of the fibers. Other observed lamellar structures may originate from lateral elements of the triads. The formation of the network structure is discussed.

Animals↗
PubMed1984

The ultrastructure of oral (buccopharyngeal) membrane formation and rupture in the anuran embryo.

The ultrastructure of the oral (buccopharyngeal) membrane was examined by transmission and electron microscopy in the anuran, Rana japonica, embryo. The stomodeum is recognizable on the ventral surface anterior to the neural folds as the neural folds are beginning to close (neural tube stage). The stomodeum is gradually enlarged and deepened as development proceeds. At the neural tube stage, the oral membrane is 5-7 cell layers thick and the stomodeal ectodermal cells are cuboidal and the foregut endodermal cells are cuboidal or columnar. Desmosomes and basal lamina could not be found between the ectodermal and endodermal epithelia. The oral membrane gradually thins between the neural tube and hatching stages. At the hatching stage, the oral membrane becomes two or three cell layers thick and each cell is flattened. Many perforations of the oral membrane after hatching and the oral membrane appears "net-like." Necrotic cells occur in the oral membrane and these cells contain many autophagic vacuoles. ACPase-positive lysosomes, Golgi regions, and autophagic vacuoles were present in the oral membrane. At the asymmetrical trunk stage, a large part of the oral membrane disappears and only remnants are left.

Animals↗
PubMed1984

Satellite cells in the tail muscles of the urodelan larvae during development.

The incidence and ultrastructure of satellite cells in the tail muscles of urodelan larvae were examined during development during which the number of satellite cells is gradually reduced. They are found more frequently in red than in the white fibres in all four stages examined (stage 53, 64, 66+ and juvenile). As development proceeds, intercellular space between satellite cell and muscle fibre is in general gradually extended and is mostly filled with basal lamina. Small muscle cells, satellite fibres, which are situated under the basal lamina of the parent fibre, are morphologically similar to satellite cells but contain a small amount of myofibrils. Three types of satellite fibres are distinguishable on the basis of differences in K2-EDTA-treated ATPase activity, width of Z line, and parent fibre type. Neuromuscular junctions are visible in satellite fibres.

Animals↗
PubMed1984

Identification of cells by backscattered electron imaging of silver stained bulk tissues in scanning electron microscopy.

Anuran tadpole tail muscle was stained en bloc by a modified light microscope silver stain for light microscopy and freeze-fractured in liquid nitrogen after partial dehydration with ethanol. The fractured specimens were observed in both secondary electron and backscattered electron modes in a scanning electron microscope. Since the cell nuclei specifically stained with silver provided high contrast against the unstained background due to atomic number contrast of backscattered electron image, various cells were easily identified by a comparison of secondary electron images and compositional images of backscattered electron signals.

Animals↗
PubMed1983

Changes in the satellite cells of the anuran tadpole tail muscles during metamorphosis.

The incidence and the ultrastructure of the satellite cells associated with red and white muscle fibres of the anuran (Rana japonica) tadpole tail were examined in three stages (hindlimb-bud, prometamorphic, and climax) during metamorphosis. In these three stages the satellite cells are found more frequently in the red fibres than in the white fibres. As metamorphosis proceeds, the incidence of the satellite cells decreases in both red and white fibres. The satellite cells in the hindlimb-bud stage have abundant cytoplasm rich in organelles. Cisternae of rough endoplasmic reticulum are often dilated. The intercellular space between the satellite cell and the muscle fibre is narrow and relatively constant (15-25 nm). Some satellite cells appear to be in the process of fusion with the muscle fibre. Cytoplasmic volume and organellar content are gradually reduced during metamorphosis. In the prometamorphic and climax stages, the intercellular space is in general gradually extended. It often exceeds 0.5 microns, and usually contains the basal lamina and fibrous materials. Some satellite cells have cytoplasmic processes that project into the interstitial space through a gap in the basal lamina.

Animals↗
PubMed1983

Electron-microscopical study of the operculum in anuran tadpole after extirpation of the right forelimb during metamorphosis.

The process of histolysis and fenestration of the skin of the prospective opercular perforation region of Rana japonica after extirpation of the right forelimb was observed during metamorphosis by transmission and scanning electron microscopy. Epidermal cells of the belly of the tadpole, including the operculum, are extremely similar in their ultrastructure. Epidermal cells of the prospective opercular perforation region during metamorphosis become thin and vacuolated especially around the nucleus perhaps by autolysis, associated with lysosomal activity. The histolysis and formation of the perforation of the operculum occurs in the complete absence of forelimb. Macrophages containing phagosomes and lymphocytes or other blood cells are almost always found in the intercellular epidermis. Necrotic epidermal cells progressively separate by cleft formation and slough off without cornification.

Animals↗
PubMed1980

Histogenesis and distribution of red and white muscle fibres of urodelan larvae.

A histochemical and electron microscopical study has been made of the myotomal musculature of an urodelan (Hynobius tokyoensis) tadpole tail and trunk. In older larvae (stage 64) two main types of fibre (small red and large white) could be distinguished on the basis of differences in fibre size, succinic dehydrogenase and adenosine triphosphatase activities, and fine structural features. The red fibres were superficial to the white ones except at the level of the notochord, where red and white were mixed in mosaic fashion. The superficial and deep red fibres were similar in their histochemical and fine structural characteristics.

Adenosine Triphosphatases↗
PubMedDate not supplied

Clonotypic analysis of T cells infiltrating the skin of patients with atopic dermatitis: evidence for antigen-driven accumulation of T cells.

Atopic dermatitis (AD) is a chronic inflammation of the skin characterized by marked infiltration of lymphocytes, suggesting an important role for cellular immune responses in the pathogenesis of AD. It is still unclear, however, whether accumulation of lymphocytes results from antigen-driven mechanisms or by nonspecific inflammatory processes. We applied a novel method of T cell clonotypic analysis, using a combination of reverse transcriptase-PCR with multiple T cell receptor (TCR) primers and subsequent single-strand conformation polymorphism (SSCP). Using this method, we were able to detect oligoclonal accumulation of T cells in inflamed skin areas of patients with AD, but not in normal skin. Identical T cell clones with the same antigen specificities were present in samples obtained from separate skin regions. Our results indicate that antigen(s) that exist in large areas of the skin stimulate and expand a relatively restricted number of antigen-specific T cells, leading to oligoclonal accumulation of T cells. We suggest that a marked antigen-driven infiltration of T cells is present in AD.

Adolescent↗
PubMedDate not supplied

Light-modulated subcellular localization of the alpha-subunit of GTP-binding protein Gq in crayfish photoreceptors.

Gq-type GTP-binding protein (Gq) plays an important role in invertebrate visual phototransduction. The subcellular localization of the alpha subunit of visual Gq in crayfish photoreceptor was investigated immunocytochemically and biochemically to demonstrate the details of the rhodopsin-Gq interaction. The localization of Gq(alpha) changed depending on the light condition. In the dark, Gq(alpha) was localized in the whole rhabdoms as the membrane-bound form. In the light, half of the Gq(alpha) was localized in the cytoplasm as the soluble form. The translocation of Gq(alpha) was reversible. The light-modulated translocation possibly controls the amount of Gq that can be activated by rhodopsin. In vitro hydroxylamine treatment of rhabdomeric membranes suggested that the translocation was regulated by the fatty-acid modification of Gq(alpha).

Adaptation, Ocular↗