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Biomedical subjects

H L de Almeida

Publications and source records attributed to H L de Almeida.

9 recordsLinked to original sources
PubMed2005

Experimental phytophotodermatitis.

BACKGROUND/AIMS: Phytophotodermatitis (PPD) is defined as a phototoxic reaction of the skin after contact with substances derived from plants and subsequent exposure to sunlight. It is a frequent disease in our outpatient clinics during summer because of contact with Tahitian lemon. Our objectives were to experimentally reproduce PPD in rats, to identify whether PPD is induced by minimal exposure periods to sunlight, to find what kinds of lemons and which parts of the lemon (the fruit juice or the peel juice) may trigger the disease; to know whether the use of sunblock prevents the reaction; and to perform light microscopy of the lesions to describe their histology. METHODS: Adult rats (Rattus norwegicus), three in each experiment, were used. After painting the rats with the fruit juice or the peel juice they were exposed to sunlight for 2.5, 5, 7.5, and 10 min. Tahitian and Sicilian lemons were used in the experiments. Biopsies with 3-mm punches of different times of exposure were performed. RESULTS: The peel juice of both lemons reproduced PPD, which was clinically evident after 48 h. When the peel juice was alone applied there was no reaction; moreover, exposure to sunlight alone triggered no reaction. Two and a half minutes of exposure time was sufficient to induce phototoxic reaction, which was time dependent (the longer the exposure the more intense the reaction). Histopathological studies showed epithelial time-dependent vacuolar degeneration. The use of sunblock diminished the intensity of the reaction but did not prevent it. CONCLUSION: PPD can be reproduced in an animal model. It may be caused by the peel juice of Tahitian and Sicilian lemon. Because of an extremely short time of exposure (2.5 min) is sufficient to induce PPD it is necessary to alert the population, of the need for caution when handling lemons, especially outdoors despite using sunblock.

Animals↗
PubMed2001

[Plantar fibromatosis with marked cutaneous involvement].

Cutaneous involvement in plantar fibromatosis is very rare. The classical finding are nodules in the plantar arch, which can be detected only with palpation. A 55 year-old man presented with a 3 year history of painful plantar nodules and an ulceration. Histopathology showed a fibroblastic proliferation with a pseudosarcomatous configuration. The immunohistochemistry was positive for vimentin, alpha-actin and desmin, a pattern which characterizes a myofibroblast. Intralesional therapy with corticosteroids did not reduce the lesions. After surgical treatment, the lesions recurred.

Fibroma↗
PubMed1993

Solid basal cell epithelioma (BCE) possibly originates from the outer root sheath of the hair follicle.

The presence and distribution of several cytokeratins (CKs) in 20 solid basal cell epitheliomas (BCEs) were investigated and compared with the pattern of CKs in normal epidermis, perilesional skin and in the outer root sheath (ORS) of the human hair follicle. Tissue samples were stained with monoclonal antibodies (MoAbs) against human CKs, using the APAAP technique. Additionally, CK profiles were assessed by gel electrophoresis and immunoblot technique. Cells of BCE and ORS were positively stained with the MoAb KL1, whereas the basal layer of normal epidermis remained negative. Six out of 20 BCEs were partially stained with the MoAb RPN1165, which also stained the lower ORS, but not the epidermal basal layer. Using SDS-PAGE and immunoblot, the CK profiles of BCE and ORS were almost identical, showing the presence of CKs 5, 6, 14, 16 and 17; the CK pattern of normal epidermis, however, showed the presence of CKs 1, 5, 10 and 14. Perilesional skin (< 5 mm) showed keratin changes similar to the BCE pattern; the basal layer was stained with the MoAb KL1 and the suprabasal layer was negative to MoAb CK1, in contrast to normal epidermis. Keratin analysis revealed a CK pattern of perilesional skin different from that of normal epidermis (CKs 1, 5, 6, 10, 14, 16 and 17). Our immunohistochemical and biochemical investigations underline the possible role of the lower ORS as a cellular pool for the generation of BCE.

Antibodies, Monoclonal↗
PubMed1992

Growth characteristics and differentiation of basal cell carcinoma in vitro--immunohistochemical, gel electrophoretic, and ultrastructural analysis.

Cell cultures were established from 48 solid basal cell carcinomas (BCC) and from the normal epidermis of the same patients. The growth characteristics and differentiation of BCC cells in vitro were compared with normal keratinocytes (nKC) by using immunohistochemistry, two-dimensional gel electrophoresis including immunoblots, transmission electron microscopy, and soft agar suspension culture. After isolation of the tumor tissue under a stereodissection microscope, explants were cultured on feeder layers of mitomycin-treated 3T3 cells. After 3-5 d, 73% of all explants of BCC could be successfully cultured showing spindle-shaped outgrowing cells. Compared to nKC, cultured BCC cells had a lower growth rate and showed a wider intercellular polymorphism regarding size and shape. Their labeling pattern with a wide panel of monoclonal antibodies showed significant differences from that of nKC. In particular, only weak reactions for various cytokeratins, filaggrin and vimentin depending on the BCC cell type (small, middle, large) were found. Two-dimensional gel electrophoresis revealed expression of keratins 5, 6, 14, 16, and 17 in BCC cells and of K 5, 6, 13, 14, 16, 17, and 19 in nKC. These findings were confirmed by immunoblot. On the ultrastructural level, only a few desmosomes and a lower degree of keratinization markers were detected in BCC cells; finally, when cultured in soft agar BCC cells formed colonies whereas nKC did not. Our findings indicate that cultured BCC cells may preserve in vitro some in vivo characteristics and maintain a growth and differentiation pattern that differs from cultured nKC. The culture model presented here provides further insights into the cytogenetic and histogenetic characteristics of BCC.

Aged↗
PubMedDate not supplied

[Heterogeneity in bibliographic references].

Bibliography plays an important role in the writing of books and papers, as it permits us an exchange of experience, the reading of case reports, the revision of articles and new investigative aspects. Bibliographic references in the same chapter of six books from different countries, published in the same period, were analyzed, and a strong heterogeneity was found among them. The "language pattern" varied depending on the author's native language. The temporal distribution of articles was also different and only a small percentage of articles was common to two or more books. Our results showed that the same chapter in different books have highly heterogenous bibliographic references, although they should have similar contents.

Bibliographies as Topic↗