Biomedical subjects

E Hoyo

Publications and source records attributed to E Hoyo.

6 recordsLinked to original sources

PubMed1993

Electron-microscopic observation of a human epidermal Langerhans cell in mitosis.

Langerhans cells are dendritic cells of the epidermis originating from bone marrow precursors which may exceptionally undergo mitosis within the skin. We report herein an electron-microscopic observation of a dividing LC within a seemingly hyperproliferative human epidermis. This observation further underlines the self-reproducing capacity of LC in situ and suggests that LC may respond to the same mitogenic stimuli as keratinocytes.

Child↗

PubMed1993

Evidence of increased keratinocyte proliferation in air-liquid interface cultures of non-bullous congenital ichthyosiform erythroderma.

Modern pharmacological and dermatological research requires the use of appropriate in vitro models which permit a faithful reproduction of various aspects of the in situ situation. The air-exposed culture of keratinocytes on dead de-epidermized dermis is one of the best models of in vitro epidermal differentiation known at the moment. In this study, we verified the model's validity for the reproduction of a hyperproliferative genodermatosis: non-bullous congenital ichthyosiform erythroderma. We used subcultured epidermal keratinocytes originating from normal and ichthyotic patients. Light and electron microscopy of pathological cultures disclosed, on day 14, a terminally differentiated epidermis with a marked granular layer and hyperkeratosis which, however, was not dramatically different from the normal controls. On day 25, the normal cultures displayed an even more pronounced hyperkeratosis and hypergranulosis, whereas the reconstructed epidermis of pathological origin presented a considerable reduction of the viable non-keratinized compartment and a focal parakeratosis. Indirect immunofluorescence revealed the expression of several differentiation markers which were not observed in the immersed culture models (e.g. the desmosome- and differentiation-related antigens KM48 and G36-19). Abundant keratohyalin granules were stained with AKH1 antibody and observed even in the deep epidermal layers, but no profilaggrin-filaggrin conversion could be detected biochemically.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Keratinocyte proliferation in epidermal keratinocyte disorders evaluated through PCNA/cyclin immunolabelling and AgNOR counting.

The assessment of cell proliferation is important to our understanding of hyperproliferative disorders. In this work we evaluated the proliferation characteristics of epidermal keratinocytes in diseases with abnormal keratinization by two different methods (immunostaining for the proliferating cell nuclear antigen--PCNA and histochemical staining for nucleolar organizer region--associated argyrophilic proteins--AgNORs). Twenty-seven specimens from diseases with an abnormal keratinization were studied and compared with specimens of normal human skin. As compared with the latter, the numbers of PCNA-positive epidermal keratinocytes were increased in psoriasis, congenital non-bullous ichthyosiform erythroderma, epidermolytic hyperkeratosis and chronic dermatitis and decreased in ichthyosis vulgaris, X-linked ichthyosis and pityriasis rubra pilaris. In most cases a parallel modification of AgNORs was found. We conclude that although PCNA immunolabelling and AgNOR staining do not provide strictly correlated values, both appear as useful markers for the assessment of keratinocyte proliferation in epidermal disorders.

Autoantigens↗

PubMed1993

[The dermal dendrocyte].

Dermal dendrocytes represent a population of resident cells of the dermis identified recently by virtue of the immunohistochemical expression of the coagulation factor XIIIa (fXIIIa). These dendritic cells of bone-marrow origin bear particular histoenzymatic and immunohistochemical features, some of which are shared with antigen-presenting cells; however, they are clearly distinct from epidermal Langerhans cells. Dermal dendrocytes could act as macrophages, antigen-presenting cells or participate in the homeostasis of macromolecules of the dermis. These cells give rise to some cutaneous tumours and seem involved in inflammatory dermatoses where they act by means of cytokine production; they could even represent targets of HIV infection. Future functional studies will hopefully lead to a better understanding of their precise role in normal and diseased skin, which remains presently partly speculative.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Proliferation characteristics of cutaneous squamous cell carcinomas developing in organ graft recipients. Comparison with squamous cell carcinomas of nonimmunocompromised hosts by counting argyrophilic proteins associated with nucleolar organizer regions.

BACKGROUND AND DESIGN: Cutaneous squamous cell carcinomas (SCCs) are a frequent complication in organ graft recipients (OGRs). The clinical evolution of these lesions has been a matter of controversy. We studied, by the technique of counting argyrophilic proteins associated with nucleolar organizing regions, the proliferative profile of 11 SCCs developing in six OGRs and compared it with the profile in a group of 18 nonimmunocompromised patients with SCCs. The density of the inflammatory cellular peritumoral infiltrate was also assessed semiquantitatively. RESULTS: The SCCs in OGRs and controls contained similar numbers of argyrophilic proteins associated with nucleolar organizing regions; however, the density of the inflammatory cellular peritumoral infiltrate was much lower in OGRs than in controls (2.00 +/- 0.77 vs 3.17 +/- 0.79). CONCLUSIONS: The proliferative potential of SCCs developing in the setting of iatrogenic immunosuppression does not seem to be different from that of SCC in nonimmunocompromised hosts; however, since metastatic SCCs are known to have a reduced density of the inflammatory cellular peritumoral infiltrate as compared with nonmetastatic cases, SCCs in OGRs could have a higher metastatic potential than similar lesions developing in a control population.

Adult↗

PubMed1992

Nucleolar organizer region enumeration in keratoacanthomas and squamous cell carcinomas of the skin.

Keratoacanthomas (KA) and squamous cell carcinomas (SSC) are epithelial skin tumors exhibiting distinctive clinical and histologic features. However, the differential diagnosis between them in individual cases may be difficult or even impossible. In this article the authors examine the possibility that enumeration of associated proteins of nucleolar organizer regions (AgNOR) could be of help in differentiating KA from SCC. AgNOR counting, performed on unequivocal cases of SCC (n = 20) and KA (n = 16) showed statistically significant higher AgNOR counts in SCC (6.29 +/- 0.91) compared with KA (3.80 +/- 1.62). This result speaks in favor of the different biologic nature of SCC and KA; however, due to significant overlap between the two groups, AgNOR enumeration alone is not sufficiently discriminating so as to be used diagnostically in cases with borderline histologic features.

Carcinoma, Squamous Cell↗