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Biomedical subjects

Y Kitano

Publications and source records attributed to Y Kitano.

At least 253 records · Page 14Linked to original sources
PubMed1980

Metabolism of benzo[a]pyrene in human epidermal keratinocytes in culture.

The metabolism of benzo[a]pyrene (BP) in cultured human epidermal keratinocytes was investigated using thin layer chromatography, high pressure liquid chromatography and cell-mediated mutagenesis assay. Epidermal keratinocytes were obtained from skin of normal subjects and all experiments were performed on primary cultures. Human epidermal keratinocytes were shown to metabolize BP. Analysis of BP metabolites by high pressure liquid chromatography indicated that epidermal keratinocytes metabolize BP preferentially at non-K-regions such as positions 7, 8, 9 and 10, forming a moderate amount of BP-7,8-dihydrodiol, a precursor of the ultimate metabolite, BP-7,8-dihydrodiol-9,10-epoxide. Conjugate formation was examined by treating the medium with beta-glucuronidase and arylsulfatase. No appreciable amount of conjugates was formed by epidermal keratinocytes, except in one culture which gave small peaks eluted in the phenol regions after beta-glucuronidase treatment. The metabolic activity of human epidermal keratinocytes on BP was further demonstrated by a cell-mediated assay, in which V79 Chinese hamster cells were cultured on top of sheets of keratinocytes and treated with BP for 48 h. Mutation of the V79 cells, demonstrated as ouabain resistance, was induced in a dose-related fashion. The extent of induced mutation was higher than that observed using rat embryo cells as the activating layer, although the shape of the dose-response curves was different.

Adult↗
PubMed1980

Keratinization of human keratinocytes in cell culture: the effect of cyclic AMP.

Human keratinocytes in culture were treated with dibutyryl cyclic AMP (DBcAMP) at concentrations of 10(-3) and 10(-4) M, and labeled with [3H]histidine for 48 hours. The proteins of the keratinocytes were serially extracted in 0.25 M sucrose, 0.1 M sodium citrate-citric acid (pH 2.6), 6 M urea-0.1 M Tris-HCl(pH 9.0), and 6 M urea-0.1 M Tris-HCl(pH 9.0) with 1% mercaptoethanol. The incorporation of [3H]histidine into the extract as assayed by DPM of 3H/microgram protein was increased in 0.25 M sucrose extract and Tris-urea extract of the cultures treated with 10(-3) M and 10(-4) M DBcAMP as compared with the control culture. There was no difference between the citrate-buffer extract of the control and that of the DBcAMP-treated cultures. The incorporation of [3H]histidine into the Tris-urea-mercaptoethanol extract was small, and this fraction was thought to be inactive metabolically. It was concluded that dibutyryl cycli AMP stimulated the protein synthesis of the cultured keratinocytes and induced a qualitative change toward accelerating the synthesis of keratinous protein.

Bucladesine↗
PubMed1976

Stimulation by melanocyte stimulating hormone and dibutyryl adenosine 3'5'-cyclic monophosphate of DNA synthesis in human melanocytes in vitro.

The proliferation of human melanocytes in vitro was stimulated by MSH. This stimulation was further intensified by the simultaneous addition of theophylline with MSH. Theophylline alone stimulated proliferation moderately. Dibutyryl cyclic AMP strongly stimulated the proliferation, but sodium butyrate, 5'-AMP and cGMP did not. The stimulation by dibutyryl cyclic AMP was continued up to 4 days so far tested. These findings are directly opposed to those on mouse melanoma cells in culture which responded with retarded growth to MSH and cyclic AMP. It is suggested that the difference of proliferation control may explain the different reaction of the melanocyte and the melanoma cells. The epidermal melanocytes seem to belong to the exceptional group of the cells which responded to cyclic AMP with accelerated proliferation.

Adult↗
PubMed1976

Effects of melanocyte stimulating hormone and theophylline on human melanocytes in vitro.

The effects of MSH on the human melanocyte in vitro were studied. The addition of MSH up to the concentration of 40 mug/ml into the culture medium did not produce appreciable change on the morphology of the melanocyte. The melanocyte, however, responded to the simultaneous addition of MSH and theophylline with marked increase in the length and complexity of the dendritic process. Melanin synthesis, as indicated by the uptake of tyrosine in the presence of an inhibitor of protein synthesis, was remarkably activated by the simultaneous addition of MSH and theophylline. MSH alone activated the melanin synthesis only slightly, but the increase in the uptake of tyrosine was significant statistically. These results were discussed in terms of the MSH-cyclic AMP cascade in which theophylline worked as an inhibitor of cyclic AMP phosphodiesterase, and increased the intracellular level of cyclic AMP by inhibiting catabolism of cyclic AMP.

Cyclic AMP↗
PubMed1976

Juvenile hyalin fibromatosis.

A boy had multiple large tumors on the scalp, whitish nodules on the nape and both sides of the neck, hypertrophic gingiva, and severe flexural contractures of hip and knee joints. The histopathologic structure of the tumor was characteristic of juvenile hyalin fibromatosis. The tumor cells were embedded in an amorphous eosinophillic ground substance. X-ray films revealed numerous osteolytic and osteociastic lesions that are important findings in the study of this disease.

Child↗
PubMed1976

Effects of dibutyryl adenosine 3',5'-cyclic monophosphate on human melanocytes in vitro.

The effects of cyclic AMP and its analogue, dibutyryl cyclic AMP (DBcAMP) on the pigmentary system were studied by using human epidermal melanocytes in culture. The melanocytes responded to 1 mM DBcAMP with an increase in number, length, and complexity of dendritic processes. The effect of DBcAMP on the dendritogenesis was reversible. Melanin synthesis, as indicated by the uptake of tyrosine in the presence of an inhibitor of protein synthesis, was significantly stimulated by DBcAMP. The maximum stimulation was observed at concentrations of 0.5 mM, and 1.0 mM. The melanin synthesis increased after 12-hour treatment with DBcAMP and continued to increase with the prolonged treatment. Cyclic AMP, theophylline, sodium butyrate, or 5'-AMP at a concentration of 1 mM did not have any remarkable effect on the morphology or the melanin synthesis of the melanocyte. The results of this investigation indicate the possible role of the MSH-cyclic AMP system in the melanin pigmentation of human skin and represent a system for further study of the pathobiology of human melanocytes.

Bucladesine↗