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Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis
Almeida Júnior, Hiram Larangeira de; Sotto, Miriam Nakagami; Castro, Luis Antonio Suita de; Rocha, Nara Moreira.
Afiliação
  • Almeida Júnior, Hiram Larangeira de; Federal and Catholic University of Pelotas. Department of Dermatology. Pelotas. BR
  • Sotto, Miriam Nakagami; University de São Paulo. Department of Dermatology. São Paulo. BR
  • Castro, Luis Antonio Suita de; EMBRAPA-CPA-CT. Laboratory of Electron Microscopy. Pelotas. BR
  • Rocha, Nara Moreira; EMBRAPA-CPA-CT. Laboratory of Electron Microscopy. Pelotas. BR
Clinics ; Clinics;63(3): 371-374, 2008. ilus
Article em En | LILACS | ID: lil-484763
Biblioteca responsável: BR1.1
ABSTRACT

OBJECTIVE:

To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy.

INTRODUCTION:

In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours.

METHODS:

The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy.

RESULTS:

No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed.

DISCUSSION:

The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation.

CONCLUSIONS:

Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.
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Texto completo: 1 Coleções: 01-internacional Base de dados: LILACS Assunto principal: Dermatite Fototóxica / Microscopia Eletrônica de Transmissão / Desmossomos / Epiderme Tipo de estudo: Prognostic_studies Limite: Animals Idioma: En Revista: Clinics Assunto da revista: MEDICINA Ano de publicação: 2008 Tipo de documento: Article País de afiliação: Brasil País de publicação: Brasil
Texto completo: 1 Coleções: 01-internacional Base de dados: LILACS Assunto principal: Dermatite Fototóxica / Microscopia Eletrônica de Transmissão / Desmossomos / Epiderme Tipo de estudo: Prognostic_studies Limite: Animals Idioma: En Revista: Clinics Assunto da revista: MEDICINA Ano de publicação: 2008 Tipo de documento: Article País de afiliação: Brasil País de publicação: Brasil