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Biomedical subjects

M Emura

Publications and source records attributed to M Emura.

At least 91 records · Page 5Linked to original sources
PubMed1982

Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golden hamster. IV. In vitro effects of dimethylsulphoxide and benzo(a)pyrene.

The biological effects of in vitro exposure of cultured fetal hamster tracheal epithelium to benzo(a)pyrene in 0.5% dimethylsulphoxide (BaP: 5 and 10 micrograms/ml medium) were studied by light and scanning electron microscopy. The solvent, DMSO, alone induced a slight, temporary retardation in development and differentiation of cilia. At day 28 of culture, however, differences in growth and maturity disappeared between DMSO-exposed and untreated explants. No dose-related differences found in the surface morphology of alterations were seen in BaP-treated tracheae; the explants revealed metaplastic foci and reduced, incomplete ciliogenesis compared to DMSO- and non-treated controls. Towards the end of the culture period, ciliogenesis tended slowly to replace epithelial alterations.

Animals↗
PubMed1982

[Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golde4n hamster. V. Dose-related in vitro effects of benzo(a)pyrene].

The biological effects of in vitro exposure of fetal hamster tracheal explants to three dose levels of benzo(a)pyrene (BaP:25, 50, 100 microgram/ml medium) in 0.5% dimethylsulphoxide (DMSO) were studied by light and scanning electron microscopy. A dose-related difference was seen in a quality of the observed pathological alterations in the specimens examined after 28 days of culture. Whilst in the explants treated with 50 or 100 microgram/ml BaP the respiratory epithelium revealed necrotic areas and extended metaplastic alterations, explants exposed to 25 microgram/ml BaP showed normal differentiation in some areas of the respiratory epithelium. In explants treated with the highest dose (100 microgram/ml BaP), hyperplastic foci were seen in the epithelium and tended to proliferate towards the tracheal lumen. These observations show similarity with early neoplastic alterations.

Animals↗
PubMed1981

Transformation-dependent quantitative changes in glycopeptide binding to concanavalin A-sepharose.

Differentially L-fucose-labelled glycopeptides from the surface of a Syrian golden hamster (SGH) fetal lung control cell line were compared with those from chemically-transformed and tumour cell lines derived from the control line by cochromatography on Concanavalin A-Sepharose (Con A-Sepharose) and Sephadex G-50. Quantitative differences were found both in the unbound and specifically-bound fractions between control and transformed cells upon Con A-Sepharose chromatography. In the glycopeptides from transformed and tumour cells, the unretarded fraction was concomitantly decreased compared to the controls. When the ratio of unbound to specifically-bound fractions was used, a statistically significant difference could be calculated between the values of control versus transformed or tumour cells. In all transformed and tumour cell lines investigated, the quantitative change in Concanavalin A binding, expressed as an increase of the ratio of unretarded to specifically-bound glycopeptides, was paralleled by a shift of transformed or tumour glycopeptides to higher apparent molecular weight compared to the control in gel chromatography.

Animals↗
PubMed1980

Sensitivity of Syrian golden hamster fetal lung cells to benzo[a]pyrene and other polycyclic hydrocarbons in vitro.

Dose responses were compared of cultured fetal Syrian golden hamster lung cells (FSHL) to the toxic and transforming effects of benzo[a]pyrene (B[a]P), benzo[b]fluoranthene (B[B]F), benz[a]anthracene (B[a]A, indeno[1,2,3-c,d]pyrene (I[c,d]P), benzo[k]fluoranthene (B[k]F) and benzo[e]pyrene (B[e]P). Effort was first given to standardising the techniques for evaluating B[a]P dose-responses. These polycyclic aromatic hydrocarbons (PAH) were then tested at concentrations of up to 1 microgram/ml, and only B[a]P showed clear cytotoxicity. The transforming effects of B[b]F, B[a]A and I[c,d]P at 1 microgram/ml appeared comparable to those of B[a]P at 0.05 microgram/ml.

Animals↗
PubMed1980

Some aspects of prenatal risk of N-nitrosodiethylamine carcinogenesis.

In the respiratory tract of the Syrian golden hamster, N-nitrosodiethylamine (NDEA) tumorigenicity is first observed on the 12th prenatal day. Thereafter, it increases with age. NDEA sensitivity coincides with cellular differentiation of the tissue and with the rapid decline of cellular proliferative activity. The hamster fetal tracheal epithelia, which have been organ cultured after transplacental pulse exposure to NDEA, develop hyperplasias, squamous metaplasias or dysplasias. These alterations occur with significantly higher frequency in the part well-differentiated at the time of exposure. Since organ culture excludes in vivo influences, these results may corroborate a closer association of tissue differentiation with prenatal NDEA sensitivity.

Animals↗
PubMed1980

Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golden hamster. I. Postnatal differentiation.

The postnatal development and differentiation of the tracheal epithelium in Syrian golden hamsters was examined by SEM. Surface structures indicate a proliferative growth for the first 10 days after delivery, but differentiation into a mature respiratory epithelium is still incomplete on the 30th day post partum. Cells with microvilli (less differentiated cells, mucus cell precursors and mucus-producing cells) outnumbered ciliated cells up to the 20th day. The topographical distribution of ciliated cells was different at various stages of development in the pars membranacea, pars intercartilaginea and pars cartilaginea. Depending on the time of their development and differentiation, the different cell types in the respiratory epithelium provide useful information on induced alterations because of the high degree of specialisation on their surface.

Animals↗
PubMed1980

Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golden hamster. II. In vitro differentiation.

Differentiation of the Syrian golden hamster respiratory epithelium (trachea) was followed sequentially for 28 days in vitro after explantation of fetal tissue. It was shown that the epithelium stays alive, develops and differentiates at time periods and with patterns similar to those observed in vivo. In general, the surface structure and topographical distribution of cell types are identical to those seen in vivo. Differentiation into mucogenic cells appeared to be enhanced to some extent towards the end of the observation period.

Animals↗
PubMed1979

Tubular explant culture of fetal Syrian golden hamster tracheae.

Two types of organ culture technique (stationary and rocking) were compared for their ability to maintain the epithelial structures in the tubular explants of fetal Syrian golden hamster tracheae. A simple new technique has been devised for the organ culture of small tubular explants of fetal tracheae. A large pore-sized membrane filter is introduced into the rocking culture, which improves unfavourable in vitro effects of the stationary technique.

Animals↗
PubMed1979

Effects of serum concentrations on the clonal growth of Syrian golden hamster fetal lung cells.

In order to gain an insight into the mechanisms of clonal growth of early-passage Syrian golden hamster fetal lung (SGHFL) cells, a study was undertaken, in which the effects of various serum concentrations on the cloning efficiency and on the colony size of these cells were examined. The results suggest that both cloning efficiency and colony size are influenced by at least two factors present in the serum.

Animals↗
PubMed1979

Tissue differentiation as a prerequisite for transplacental carcinogenesis in the hamster respiratory system, with specific respect to the trachea.

The significance of tissue differentiation for the transplacental carcinogenicity of DEN was examined. In one experiment, pregnant Syrian golden hamsters received a single sc injection of DEN on one of the different days of pregnancy. Approximately 95% of the offspring of those mothers treated on one of the last 4 days (days 12--15) of gestation developed respiratory tract tumors. Transplacental DEN treatment before the 12th prenatal day failed to induce any neoplastic response in the young. In the second experiment, the differentiation of the prenatal Syrian golden hamster tracheal epithelium was examined histologically and by electron microscopy. We found that on the 12th prenatal day the ER occurred for the first time in its functionally competent form. On earlier prenatal days, the epithelial cells lacked this organelle. We conclude that this development of ER is a prerequisite for transplacental DEN carcinogenesis, since this organelle contains the nonspecific enzyme systems necessary for the transformation of DEN to its ultimate carcinogen.

Animals↗
PubMed1978

Epithelial alterations in fetal tracheal explants of Syrian golden hamsters exposed to diethylnitrosamine in utero.

The fetal tracheae (13th--15th day of gestation) of Syrian golden hamsters exposed in utero to diethylnitrosamine (DEN: 200--400mg/kg body wt.) were divided into cranial and caudal halves. Both sections were then organ-cultured for 4--6 weeks. The cranial explants developed 1.5 times as many epithelial tracheal lining alterations as the caudal explants. These changes were found 25--42 days after the beginning of explant culture and histologically demonstrated hyperplasia, metaplasia and dysplasia. No alterations occurred in the control explants.

Animals↗
PubMed1978

Toxic and transforming effects of polycyclic hydrocarbons in fetal hamster lung-cell cultures. I. Benzo(alpha)pyrene.

When seeded at a low cell density in Petri dishes not pre-conditioned with feeder layers, fetal hamster lung cells at 2-4 passages grew with greatly varied plating efficiencies (PE). Addition of insulin to the serum-supplemented medium gave relatively constant PE. However, the presence of insulin in the medium enhanced the toxicity of benzo(alpha)pyrene (BP) on these cells. Cytotoxic and cell transforming effects of BP in the presence of insulin were studied.

Benzopyrenes↗