Biomedical subjects

W Böning

Publications and source records attributed to W Böning.

6 recordsLinked to original sources

PubMed1986

Growth stimulation by retinol apparently independent of EGF receptor.

A respiratory epithelial cell line M3E3/C3, derived from fetal Syrian hamster lung, grew very slowly in RPMI 1640 medium with serum concentrations as low as 1.5%. Under these conditions the simultaneous action of epidermal growth factor (EGF) and vitamin A (retinol) was apparently a combination of growth enhancement attributable to each compound. Both compounds also affected the morphological growth pattern considerably. Binding experiments with 125I-labelled EGF showed that retinol had only a small (if any) reducing effect on the numbers of EGF receptors. Nonetheless, retinol showed a marked growth stimulation. As far as we are able to judge from most of the other reports that retinoids inhibited growth of cells and increased the EGF receptor number, this type of growth regulation is unusual.

Animals↗

PubMed1984

Ultrastructural findings in the oral mucosa of betel chewers.

Eighteen biopsies of the oral mucosa of northern Thai hilltribe betel chewers were studied histologically and by transmission and scanning electron microscopy (TEM, SEM). Clinically, varying stages of epithelial atrophy and one case of submucous fibrosis were observed. Histologically, epithelial atrophy with marked reduction of the rete pegs, hyperortho- and/or parakeratosis, and subepithelial edema and inflammatory changes were the prominent findings. On the ultrastructural level, cytoplasmic projections of the basal cells into the subepithelial stroma were seen. The basal membrane frequently revealed gaps; the interepithelial space was widened and unusual microvilli were observed on cell surfaces (SEM). Intercellularly, cristalloid material of unknown origin was also seen. The subepithelial connective tissue was characterized by dense bundles of collagen fibres adjacent to which masses of amorphous material were located. While some of the ultrastructural findings in the epithelium of betel chewers are indicative of early dysplastic changes, the nature of the juxta-epithelial stromal alterations is still unknown. Current hypotheses regarding the etiology of oral submucous fibrosis are briefly discussed.

Adult↗

PubMed1983

Transplacental effect of N-diethylnitrosamine on chromosomal aberrations in fetal tracheal cells of the Syrian hamster: comparison between epithelial and mesenchymal cells.

Chromosomal aberrations were investigated in tracheal cells of fetal Syrian hamsters after transplacental administration of N-diethylnitrosamine (DEN). On the 15th day of pregnancy, Syrian hamsters were injected s.c. with a tumorigenic dose of DEN (50, 100 and 200 mg/kg body weight). Two hours later, the fetal tracheae were isolated, the epithelial tissue was separated from the mesenchymal tissue by collagenase-treatment, and then each cell population was transferred to cell culture after Dispase treatment. At 24, 48 and 72 h after the cell cultivation, chromosomal damage was examined. The results clearly showed that a high incidence of chromosomal aberrations, especially chromatid-type exchanges, was seen in the epithelial cells of DEN-treated groups. However, significant induction of chromosomal aberrations was not observed in the mesenchymal cells from DEN-treated groups.

Animals↗

PubMed1982

Characterization of a control switch in chymotrypsin.

Kinetic and thermodynamic parameters of the conformational change accompanying the binding to chymotrypsin of a substance carrying substrate specificity have been determined by a chemical relaxation method. An analysis of the concentration dependence of the two relaxation times and the associated amplitudes permitted the evaluation of rat constants, reaction enthalpies, and entropies of the individual steps. The pH and temperature dependencies of these parameters allowed, together with the known topography of the molecule, the identification of the ionizing groups involved in the regulation of the two steps. The combined evidence was used to compose a detailed mechanism for the function of the conformational change. The hypothesis is proposed that the side chain of ASp-194 is acting as the tongue of a switch which is moving between the positively charged His-57 side chain (catalytically inactive state) and the positively charged alpha-amino group of Ile-16 (active state), thus activating or deactivating the catalytic site. This control switch is very sensitive to changes in pH and temperature.

Binding Sites↗

PubMed1982

A fetal respiratory epithelial cell line for studying some problems of transplacental carcinogenesis in Syrian golden hamsters.

Using repeated cloning and treatment with cis-HPL (200 micrograms/ml), an analogue of a procollagen precursor inhibitory to the growth of collagen-synthesizing cells of mesenchymal origin, clonally premature epithelial cell lines were isolated from fetal SGH lungs cultured on the 15th day of gestation. One of the cell lines, M3E3/C3, which has been extensively studied for biological characterization, developed poorly differentiated carcinomas in injected hamsters after transformation by MNNG. Moreover, when grown on collagen gel, this cell line indicated an obvious potency for in vitro differentiation in response to vitamin A by developing activated Golgi regions, well developed rER and a number of mucus-like granules. Since such a differentiative responses is expected to be definable in the light of respiratory epithelium developing in utero, this cell line may be useful for studying mechanisms of differentiation-dependent sensitivity of fetal organs to transplacental carcinogen exposure.

Animals↗

PubMed1982

Chromosomal aberrations in tracheal epithelial cells of the fetal Syrian golden hamster after transplacental N-diethylnitrosamine administration.

Transplacental effect of N-diethylnitrosamine (DEN) on chromosomal morphology, was investigated in fetal tracheal epithelium of Syrian hamsters. At the 15th day of pregnancy, Syrian golden hamsters were injected subcutaneously with a tumorigenic dose of DEN (50, 100 and 200 mg/kg body wt). Two hours later, the fetal tracheae were isolated, epithelial cells of the respiratory mucosa were separated from mesenchymal tissue and were transferred to cell culture. At 24, 48 and 72 h after cultivation, chromosomal damages were examined. The results showed clearly that a high incidence of chromosomal aberrations, particularly chromatid-type exchanges, were seen in the epithelial cells from DEN-treated groups.

Animals↗