Search PubMed⌕ Search

Biomedical subjects

S Fujimoto

Publications and source records attributed to S Fujimoto.

At least 1,135 records · Page 63Linked to original sources
PubMed1975

Interaction of aflatoxin B1 with DNA.

The interaction of aflatoxin B1 with DNA was investigated. In the presence of native DNA the absorption spectrum of the toxin showed an obvious spectral shift in the region of 300-420 nm with an isosbestic point at 376 nm. DNA-bound aflatoxin is hydrolyzed in alkaline media more easily than the free toxin. The hydrolized form has a labile structure and can decompose further. The bound toxins are easily dissociated by heat as well as by salt, and all toxin molecules are released from DNA which remains double-stranded. Aflatoxin can bind to thermally denatured DNA as well, with an accompanying spectral shift which depends on the particular preparation of denatured DNA, and there was an isosbestic point at 380 nm. The complex of toxin and denatured DNA was stabilized by salt up to 0.1 M. Thus it was concluded that aflatoxin was bound with denatured DNA in a different form from native DNA. The number of binding sites of DNA was estimated by constructing Scatchard plots based on both spectral analysis and equilibrium dialysis. However, these show no definite value but fall in the region of 0.07 to 0.013, that is one toxin molecule per 80-140 nucleotide of native DNA. Several lines of evidence suggest the possibility that aflatoxin exists in aqueous solution as aggregates. The mechanism of the binding was discussed. It is noteworthy that the number of binding sites of DNA doubles by the presence of histones.

Aflatoxins↗
PubMed1975

The wall structure of the arteries in the corpora cavernosa penis of rabbits; light and electron microscopy.

Wall structures of the arteries in the corpora cavernosa penis were observed in rabbits. The deep (central) arteries in the proximal part of the penis have five or more independent ridges of the wall which are formed by the internal layer of the media consisting of almost longitudinal muscle cell layers. Electron microscopy of these regions revealed that the endothelial cells are connected to each other by many maculae and zonulae adherentes, and that smooth muscle cells of the media are separated from one another by a wide intercellular space embedding abundant collagenous fibers. The epithelioid cells constituting the media of the helicine branches of the deep artery vary in their fine structure from close resemblance to muscle cells, to cells with easily identified special features. Frankly epithelioid cells have few scattered cytoplasmic filaments of a single type, 60-90A in diameter, abundant ribosomes, active Golgi, and other features different from the typical smooth muscle cells. There is no suggestion that these epithelioid cells are either degenerative or undifferentiated forms of smooth muscle cells, as postulated by light microscopists. Transitions from muscle to epithelioid cells are consistent with, but not proved by, our data.

Animals↗
PubMed1975

Electron microscopy of endothelial microvilli of large arteries.

Scanning electron microscopic investigations by others have revealed "hair-like" projections from the endothelial surface of the rabbit aorta. We have confirmed by transmission electron microscopy that endothelial microvilli are found, in a limited number of areas in the aortic arch, particularly at the presumed site of fetal origin of the ductus arterious and near the origin of the subclavian artery. The microvilli are almost uniform in diameter (about 0.1 mum) and are as long as 3 mum in length. The outer leaflet of the limiting membrane shows a fuzzy appearance, and thin filaments are recognized in their interiors. A profuse array of endothelial microvilli was also found over the entire surface of the large arteries of human fetuses. The possible hemodynamic significance of these processes is discussed.

Animals↗
PubMed1975

Mössbauer effect and electron paramagnetic resonance studies on yeast aconitase.

Mössbauer effect and electron paramagnetic resonance (EPR) were measured for yeast aconitase [EC 4.2.1.3] purified from the cells of Candida lipolytica (ATCC 200114). Mössbauer spectra suggested that yeast aconitase nostly contained two high-spin Fe(III) ions in an antiferromagnetically coupled binuclear complex that resembled oxidized 2 Fe ferredoxins, together with a small amount of high-spin Fe(II). EPR spectra recorded no signal at 77degreesK, but showed a slightly asymmetric signal centered at g=2.0 at 4.2degreesK, presumably due to the small amount of Fe(II) Fe(III) pairs.

Aconitate Hydratase↗
PubMed1975

Ultrastructural alterations in rabbit taste buds induced by prolonged treatment with cycloheximide.

Prolonged administration of cycloheximide, an inhibitor of ribosomal protein synthesis, induces degeneration of rabbit taste bud cells: the degenerative changes resemble early changes in denervated taste buds. Our observations show that the pattern of degeneration is quite different in the three cell types of the taste buds. The earliest changes in type II and III cells are an increase in cytoplasmic filaments and extreme dilatation of rough endoplasmic cisternae. Profiles of dead type I and II cells vastly increase in number. Type I cells appear less affected by the drug and the only sign of degeneration was an increase in the number of autophagic vacuoles in their cytoplasm. There was no indication that degenerating type I cells undergo transformation to type II or III cells. These findings support our hypothesis that type I, II and III cells represent distinct cell types and do not undergo transformation to other types in the course of their life span.

Animals↗
PubMed1975

Immunosuppressor T cells in tumor bearing host.

Thymus or spleen cells of tumor bearing animals (TBA) (methylcholanthrene induced sarcoma bearing A/Jax mice) were shown to possess immunosuppressor cells regulating the immune response to the tumor in syngeneic animals. The immunosuppressive activity of these cells of TBA was totally abolished by the in vitro treatment of anti-theta serum and complement. Soluble factor(s) with identical suppressive activity was isolated from the thymus cells of TBA and its molecular size was estimated to be lower than that of serum albumin in terms of its elution behaviour on gel filtration through a Sephadex G-200 column. These immunosuppressor T cells or their soluble factor(s) may be largely responsible for the growth of antigenic tumors.

Animals↗
PubMed1975

[Inhibitory effect of taurine on ouabain-induced arrythmia].

Myocardial taurine level was found to be greater in the rat than in the guinea-pig. Taurine inhibited the development of arrhythmias caused by the i.v. infusion of ouabain in the rat. When ouabain induced arrhythmias, the myocardial taurine level decreased. Both effects were blocked by pretreatment of propranolol. The uptake of taurine into the heart did not necessarily result in the reversal of the PR interval prolonged by ouabain. The protecting effect of taurine against ouabain toxicity was not dependent upon the change in myocardial total ATPase activity.

Adenosine Triphosphatases↗