Biomedical subjects
Publications and source records attributed to M Heenen.
Seborrhoeic dermatitis, psoriasis and atopic dermatitis in infants were studied morphologically and autoradiographically on skin biopsies. A similar picture with an increased germinative cell population and accelerated cell turnover has been found in psoriasis and seborrhoeic dermatitis. These features may suggest a relationship between both diseases.
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An in vitro double labeling technique with 3H-Tdr has been used to study the cell renewal in three cases of lamellar ichthyosis. Each case was characterized by a rapid rate of cell proliferation as it occurs in psoriasis. But, in contrast to psoriasis, lamellar ichthyosis has no increased proportion of germinative cells and exhibits prominent granular layer. Horny layer at light microscopy is mainly orthokeratotic. This indicates that increased mitotic activity alone cannot account for the typical acanthosis of psoriasis.
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The DNA synthetic (S) phase of cell division is about twice as long in human basal cell carcinoma (BCC) as the normal epidermis and several non-malignant skin diseases. A similar increase in S phase duration seems to occur in tumours of the human oesophagus, larynx and recto-colon. At the molecular level, the overall rate of replication in a nucleus is determined by two factors--the frequency of initiation of replication and the rate of replication fork progression along the units of replication (for review see refs 7,8). Here we present evidence (based on DNA fibre autoradiography) that the observed increase in S phase duration may be due to a marked reduction in the rate of DNA replication along replication units, the density of simultaneously operating replication units remaining unchanged. This indicates an alteration in some biological component(s) of DNA synthesis in BCC that is of potential interest for characterizing the malignant transformation of the epidermal cell and that may perhaps be exploited therapeutically.
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We report a case of Kawasaki disease in which some unusual symptoms, including petechiae, an urticaria-like eruption, and necrotic pharyngitis, made the diagnosis difficult. No complications were detected during a follow-up period of 15 months.
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Computer simulation using a two-phase model of the cell cycle has demonstrated that a transitory shift in the normal balance between the rate of cell flow to the differentiated and that to the proliferative compartment is sufficient to cause a permanent increase in the germinative population, thus resembling the alteration found in psoriasis. This shows the coherence of the hypothesis that cell kinetic parameters need not necessarily be expected to differ in psoriasis as compared with normal epidermis. This theoretical demonstration raises the possibility that the psoriagenic agent need not necessarily be present as long as the symptoms of psoriasis persist. From a therepeutic point of view this has implications that are sifficiently evident to warrant communication of this work.
Cell kinetic of human epidermis has been studied with different techniques of labeling by 3H-thymidine. A review of the literature for human epidermis, psoriasis and some epidermal tumors has been performed and discussed in the light of our own studies. If the cell cycle time seems to be slightly shorter in epidermal tumors in comparison to normal epidermis, this doesn't constitute the fundamental characteristic of the neoplastic lesions. Indeed the most specific alteration in the cell cycle parameters for precancerous and cancerous tissue is a lengthening of the S phase duration. This modification of the DNA synthesis time is perhaps of reflection of the depressed state of the chromatin of neoplastic tissues.
Effect of a pig skin extract (72-81/ethanol precipitate from crude waterextract) was investigated on the ear epidermis, vaginal and uterine mucosae of spayed mice. This extract has a strong inhibitory effect on the epidermis. Inhibition was less marked on the vaginal mucosa while uterine epithelium was not affected. After stimulation of the proliferative activity by oestrogen a pronounced inhibition was detected in the three tissues. Purification of the crude extract by pronase treatment followed by chromatography on Sephadex G200 allowed the separation of three fractions. Two of these fractions (phenol extract and low molecular fraction) were active on epidermis vagina and uterine. The high molecular weight fraction has mainly a marked action on uterine epithelium. No effect was detectable on intestinal tissues with any fraction.
A double labeling method with two levels of tritiated thymidine was used to study 6 patients with seborrheic keratosis, 1 with a fibroepithelial tumor of Pinkus, and 1 with basal cell nevus syndrome manifesting three pits on the palm of the hand. The two latter types of lesions, known to be able to evolve into basal cell carcinoma, had an increased S-phase duration (18 hr for the germ cells of the palmar pits) as compared with normal epidermis (10 hr). This situation was similar to that observed in basal cell carcinoma, However, the S phase was not lengthened in seborrheic keratosis (9.2 plus or minus 1.6), a benign tumor in which malignant transformation is extremely rare. S phase was also of normal duration in the benign eosinophilic septa of the tumor of Pinkus.
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