Search PubMed⌕ Search

Biomedical subjects

J Tokunaga

Publications and source records attributed to J Tokunaga.

At least 37 records · Page 2Linked to original sources
PubMed1980

Changes in cyclic nucleotide levels and dimorphic transition in Candida albicans.

The relationship between the levels of cyclic nucleotides and dimorphic transition in Candida albicans was examined. The results showed that cells of this pathogenic fungus contained both cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP), the concentration of the latter being about one-tenth that of the former in stationary-phase cells of the yeast form. Our results further indicated that germ tube formation induced by incubation at 40 degrees C followed a rise in cAMP concentration in the cell with no accompanying change in cGMP content. Cysteine, which suppressed germination, also reversed the increase in intracellular cAMP concentration. Dibutyryl cAMP (1 MM) significantly promoted germination in proline medium at temperatures of 32 to 34 degrees C. These results suggested that cAMP was one of the controlling factors in the morphological transition in Candida albicans.

Bucladesine↗
PubMed1979

Immunohistological staining of antigens on semithin sections of specimens embedded in plastic (GMA-Quetol 523).

Glycol methacrylate-Quetol 523, introduced by Kushida (1977) for combined light and electronmicroscopy studies at low magnification, also permits application of immunofluorescence methods to semithin sections. To recover the antigenicity of proteins fixed with formaldehyde, abrupt dehydration before embedding and subsequent treatment of the semithin sections with protease were essential. Post-staining with suitable histological stains allows exact correlation of antigen localization with tissue structure.

Acrylic Resins↗
PubMed1977

A scanning electron microscope study of the human Bowman's epithelium.

The parietal epithelium of the Bowman's capsule in normal human kidney was studied by scanning electron microscopy. Stereoscopic scanning electron microscopy showed clearly that the Bowman's capsule, cut in half by a razor blade, was depressed hemispherically and coated with a flat layer of polygonal epithelial cells. The epithelial cell had a round, slightly elevated, and eccentrically located nuclear portion, and extended flat cytoplasmic layer from it toward the periphery. Tiny cytoplasmic projections, microvilli, were seen in varying degrees on the surface. One or two thin and long cilia were occasionally present around the nuclear portion.

Epithelium↗
PubMed1976

Scanning electron microscopy of the glomerular filtration membrane in the rat kidney.

The rat kidney was perfused with saline and glutaraldehyde, treated with Murakami's tannin-osmium impregnation method, ethanol-freeze cracked and dried by the critical point method. Gold-palladium evaporated specimens were observed in a field-emission scanning electron microscope. The glomerular filtration membrane, fractured in different planes was observed with the following results: 1. Adjacent pedicles originate from different podocytes. No interpedicular bridges of apparent cytoplasmic nature could be found. 2. The basement membrane, in grazing fractures shows a horizontally layered architecture. 3. The attenuated endothelial sheet (lamina fenestrata) is divided into compartments, which we suggest should be called "areolae fenestratae", by cytoplasmic crests radiating from the nucleated portion of the endothelial cell. A crest also occurs along the cell margin, which contacts a similar crest at the margin of the adjacent cell. 4. The pores in the areolae fenestratae are variable in size (30-150 nm diameter). A knob-like projection from the apparently naked basement membrane is found in a portion of the pores. 5. Numerous microvilli may occur on the endothelium. Some of them anastomose and fuse with one another to form a net whose meshes appear identical with the endothelial pores. Domes and shelves formed of a fenestrated cytoplasmic sheet also occur above the ordinary level of the endothelial lining. A hypothesis implicating microvilli in the partial renewal of the endothelial sheet is proposed.

Animals↗
PubMed1976

Ferritin as a surface marker for immunoscanning electron microscopy. observation of individual ferritin particles on erythrocytes.

This paper comprises a part of our study to examine whether ferritin can be used as an immunological surface marker for high resolution scanning electron microscopy. In the first part of the study individual ferritin particles in a sample of purified ferritin were demonstrated as spheres with a diameter of about 170 A by use of fixation by glutaraldehyde and thin coating by ion sputtering. In the second part of this study, ferritin particles as indicating the antigen sites of blood group A were also recognized on the erythrocytes by the same techniques as in the first part. Ferritin deposition differed in amount among the erythrocytes, but without regard to the shape of the cells. On the individual erythrocytes, heavier depositions tended to occur in the concavity of the cell. In conclusion, ferritin is useful as a surface marker in immunoscanning electron microscopy. It has the benefit, in comparison with the other markers hitherto reported, of allowing us to observe the fine features of the cell surface under immunological reaction.

ABO Blood-Group System↗