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C Delescluse

Publications and source records attributed to C Delescluse.

At least 37 records · Page 2Linked to original sources
PubMed1982

Effect of phorbol esters on guniea pig skin in vivo.

When topically applied to guniea pig ear skin the tumor promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induced inflammation and epidermal hyperproliferation which could be inhibited by indomethacin. This inhibition could be reversed both by prostaglandins E and F. Five minutes after TPA treatment an increase in the level of prostaglandin E but not of prostaglandin F was observed in the epidermis. The non-promoting phorbol ester 4-O-methyl-TPA also stimulated epidermal cell proliferation but this stimulation was not inhibited by indomethacin. The above results are in agreement with those already reported in the mouse system with these two compounds. Ornithine decarboxylase (ODC) activity has been evaluated in the epidermis of guniea pig ear after topical application of 20 nmol of TPA. No increase was noted. This is in contrast with the well documented activation of ODC in mouse skin treated with TPA. Since TPA acts as a promoter in the mouse whereas both croton oil and TPA have no promoting action in the guinea pig, the above result supports the view that ODC activationis related to promotion, and provides a possible explanation for the resistance of this animal species to promotion. This resistance is further documented by the fact that no "dark cells" were found in guinea pig ear skin.

Animals↗
PubMed1982

Effects of phorbol esters on basal epidermal cells derived from ear skin of adult guniea pigs.

In cultures of basal epidermal cells obtained from ear skin of adult guinea pigs, the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate induces cellular proliferation which is prostaglandin dependent and inhibited by indomethacin. Inhibition by indomethacin can be overcome by prostaglandins E2 and F2 alpha, with prostaglandin F2 alpha being more effective. The concomitant induction of ornithine decarboxylase activity is insensitive to indomethacin inhibition. The nonpromoting derivative 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate evokes a prostaglandin-independent, i.e., indomethacin-insensitive, stimulation of cell proliferation without inducing ornithine decarboxylase activity.

Animals↗
PubMed1979

Microflowfluorometric evaluation of homeostasis in cultured epidermal cells.

In isolating and culturing in vitro populations of basal cells from adult guinea pig skin, it has been possible to show that these cells are sensitive to both G1 and G2 inhibitions. Only a small fraction (10 percent or less) of the G1 blocked cell population would be governed by G1 inhibitory messages released by suprabasal, maturing keratinocytes. As regards the G2 block in vitro experiments confirm that basal cells produce a G2 blocker to which about 9 per cent or less are susceptible. In conclusion basal cells in culture are sensitive to homeostatic regulation as in vivo.

Animals↗
PubMed1979

Physiological regulation of epidermal cell growth.

According to the negative feedback theory, epidermal growth is regulated in vivo (at least in part) by the combined action of two inhibitors upon the basal cell proliferative pool. One blocks 85% of basal cells in G1 the other blocks 5--10% in G2. When isolating and culturing in vitro populations of basal cells from adult guinea pig skin, it has been possible to confirm that these cells are sensitive to both G1 and G2 inhibitions. However, only a small fraction (10% or less) of the G1 blocked cell population would be governed by G1 inhibitory messages released by suprabasal, maturing keratinocytes. As regards the G2 block in vitro experiments confirm that basal cells produce a G2 blocker to which about 9% or less are susceptible. The relatively good correspondence between in vitro and in vivo experimental data point to the interest of adult isolated epidermal basal cell cultures as a model for the study of epidermal growth regulatory mechanisms.

Animals↗
PubMed1978

Homeostatic regulation of epidermal cells in culture.

The growth potential (DNA synthesis) of purified epidermal basal cells in culture, according to time reveals two peaks, at days 1 and 6. The same potential estimated in total cultures of epidermal cells (including basal and high level cells) shows only one peak at day 9. This suggests that hig-level mature cells inhibit DNA synthesis in basal cells in culture. This interpretation has been confirmed in showing that increasing amounts of mature cells inhibited DNA synthesis in basal cells in a dose dependent manner. Basal cells in culture are therefore susceptible to homeostatic regulation. However, this regulation is not tissue specific since DNA synthesis was also inhibited by mature epidermal cells in cultures of dermal as well as bone marrow cells. Assuming that the culture of epidermal cells is representative of the in vivo situation, these experiments would suggest that the specificity of action of the G1 chalone in vivo might depend as much on the target tissue as the proper nature of the inhibitor.

Animals↗
PubMed1978

Studies on guinea pig skin cell cultures. VII. Statistical analysis of growth and maturation.

Thymidine uptake; incorporation of amino acids into perchloric acid extract and HCl extract (corresponding grossly to poorly and highly organized proteins respectively); cell fraction DNA and cell fraction protein contents have all been measured daily from day 1 to day 8 in primary cultures of epidermal keratinocytes (EK) and dermal fibroblasts (DF). Correlations between these five biochemical parameters (or variables) have been sought when using the statistical method of principal component analysis. The analysis of whole data of EK and DF populations taken together revealed that DNA content is a major distinguishing factor between these two cell types. The analysis of variables of each cell type taken independently showed that DF are essentially characterizable by their tendency to synthesize both poorly and highly organized proteins, whereas EK are more prone to DNA and highly organized protein synthesis. Thus, EK and DF in culture can be readily distinguished statistically by analysing their growth and maturation characteristics. It is even likely that time study of thymidine and amino acid incorporation would suffice to characterize these two cell types in vitro.

Amino Acids↗
PubMed1977

Studies on guinea pig skin cell cultures. VI. Growth kinetics of epidermal keratinocytes and dermal fibroblasts.

The growth kinetics of epidermal keratinocytes (EK) and dermal fibroblasts (DF) have been determined by four different methods: incorporation of 3H-thymidine into DNA (3H-microgram DNA ratio); 3H-thymidine/14C amino acid incorporation ratio (3H:14C ratio); 3H-thymidine labelled nuclei, and colchicine-blocked metaphase counts. The growth curve of EK was no different when plotted with the 3H:14C ratio than with the 3H-microgram DNA ratio. However, this was not true for DF. The replacement of sodium bicarbonate with Hepes buffer in the culture medium did not greatly affect the shape of the EK growth curve, whereas the DF growth curve became diphasic instead of monophasic. The elimination of mature (differentiated) keratinocytes from the very onset of EK culture had a profound effect on the EK growth curve. DNA synthesis peaked at day 1 in cultures without, instead of day 9 in cultures with differentiated cells. Furthermore, mitotic activity did not show up before day 6. This suggests that (i) EK in culture are sensitive to the G1 inhibitor released by differentiated epidermal cells, and (ii) they remain in G2 for about 5 days. Thus, EK in culture seem to continue to be susceptible, as in vivo, to homeostatic regulation through the action of G1-G2 inhibitors.

Animals↗
PubMed1976

The culture of skin. A review of theories and experimental methods.

Two main criticisms can be leveled against the standard methods of skin culture: they are poorly quantifiable and the cultured cell populations are heterogeneous. A new technique based mainly on enzymatic dissociation allows specific cell types to be extracted from the skin before cultivation. In this way, separate cultures of epidermal keratinocytes and dermal fibroblasts can be obtained from the same piece of skin. These purified systems have been used to study the kinetics of epidermal cell growth and to quantify the effect of various chemically defined substances on the growth and differentiation of keratinocytes. With further refinements in technique, purified populations of melanocytes can be extracted. The co-culture of pigmented melanocytes with albino keratinocytes has been proposed as a model to study pigment donation in vitro. The usual organ culture technique, including the use of large explants of skin immersed in the culture fluid, has been modified to show that adult human skin partially regenerates in vitro and that mitotic activity goes on for months in the regenerated epidermis. The use of nucleic acid hybridization techniques, combined with skin cell cultures from human tumors, opens new avenues of research on human cancer.

Amino Acids↗