An Improved (Paraffin Section) Method for the Dopa Reaction

Becker, S. William

doi:10.1001/archderm.1935.01460200034003

Cited by 64 publications

(7 citation statements)

References 5 publications

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“…For hinochemical purposes, the specimens were snap frozen m dry ice and cut on a cryostat. Sections were stained with a modified DOPA method (Becker, Praver & Thatcher, 1935) to reveal tyrosinase activity and were incubated according to Grogg & Pearse (1952) to demonstrate acid-phosphatase.…”

Section: Light Microscopymentioning

confidence: 99%

Pathogenesis of diffuse melanosis secondary to malignant melanoma*

Konrad

Wolff

1974

Br J Dermatol

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SUMMARY The heavily pigmented but otherwise normal appearing skin of a patient with diffuse melanosis secondary to metastatic malignant melanoma was examined by electron microscopy and electron microscopic cytochemistry. The findings indicate that the slate‐blue colour of this melanosis is due, for the most part, to melanosomes derived from melanoma cells that have spread to and throughout the skin of the patient. The dissemination of individual, discrete tumour cells within the patient's dermis represents a unique form of single cell metastasization.

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Section: Light Microscopymentioning

confidence: 99%

Pathogenesis of diffuse melanosis secondary to malignant melanoma*

Konrad

Wolff

1974

Br J Dermatol

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“…a Strong positive staining for melanin and agen. melanocytes in hair follicles in anagen (arrow), b negwere fresh or fixed frozen in liquid nitrogen and lon gitudinal sections, cut at 20 /nn incubated in a fresh medium containing 100 mg of D, ¿-dihydroxyphenylalanine (dopa) in 100 ml of 0.1 M phosphate buffer, pH 7.4 at 37 C for 2-4 h to demonstrate dopa-oxidasepositive cells [Becker et at., 1935]. Control sections were carried through the method (minus the dopa).…”

Section: Methodsmentioning

confidence: 99%

Melanin and dopa-positive cells in the skin of tropical cattle

Amakiri¹

1979

Cells Tissues Organs

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Various histochemical and histological techniques were used to study the melanin and dopa-positive cell.distribution in the skin of some tropical and temperate breeds of cattle in Nigeria. Melanin pigments were concentrated in the basal and lower spinous layers of the epidermis and in the hair cortex, follicle sheaths and papillae of the various breeds. In the White Fulani and N’Dama breeds, melanin pigments were however found in all layers of the epidermis. Dopa-positive cells (melanocytes) were observed in the epidermis, dermis and hair follicles; the distribution pattern varied among breeds, being copiously disposed in the basal epidermis and papillary dermis in the White Fulani and Muturu and, except in areas of thick epidermal ridges, scanty in the epidermis and dermis of the Friesian and N’Dama. Mast cell distribution pattern in the various breeds was similar to that of the dopa-positive cells. Peroxidase-positive cells were present in the basal epidermis and upper dermis of the Muturu, widespread in the subepidermal layer of the N’Dama and very scanty in the dermis of the White Fulani and Friesian. Acid phosphatase activity was intense in the granular layer of the Muturu and N’Dama breeds and also in the papillary dermis and hair follicles, whereas alkaline phosphatase-positive dendritic cells, and ‘clear’ cells were also observed in the basal and upper epidermis.

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“…Pure melanocyte cultures were obtained after the third passage using selective detachment with trypsin/EDTA. The cultures were checked by the DOPA reaction, using the method of Becker et al (1935), with a modification. Cultures were briefly washed with PBS, fixed in 2% normal saline/ 0.05% glutaraldehyde for 1 hr at +4"C. After washing the cells were incubated in 50 mM NH4C1, permeabilized with 0.05% saponin in PBS and exposed to 5.6 mM dihydroxyphenylalanine (L-DOPA) (Sigma, St. Louis, MO) at +37"C, in an atmosphere containing 5% COz until a dark staining was observed.…”

Section: Identification Of Melanocytesmentioning

confidence: 99%

The Proteolytic Potential of Normal Human Melanocytes: Comparison With Other Skin Cells and Melanoma Cell Lines

Bízik

Bessou

Felnerova

et al. 1996

Pigment Cell Research

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To understand the contribution of epidermal melanocytes in the proteolytic potential of human skin, we have studied melanocytes grown in a low-serum medium deprived of phorbol esters, cholera toxin, and other non-physiological supplements. We focused on the plasminogen activation system and certain matrix metalloproteinases (gelatinases). Supposing that the proteolytic activity of cells can influence binding to collagen matrix and its reorganization, we have analyzed these parameters as well. We found that human melanocytes secreted tissue-type plasminogen activator and utilised it to generate cell-bound plasmin. No urokinase-type plasminogen activator was detected in the cultures but its receptor was found in cell extracts. Both the 72 kDa and 92 kDa gelatinases were secreted by the cells and in equal amounts. In addition, melanocytes secreted the wide-spectrum proteinase inhibitor alpha-2-macroglobulin. Melanocytes cast into collagen matrices retained a rounded morphology, did not extend processes, and were unable to contract collagen lattices. As a control, these parameters were investigated in parallel in cultures of human keratinocytes, dermal fibroblasts, and two melanoma cell lines. The obtained characteristics suggest that normal human melanocytes are proteolytically active cells. This function may pertain to skin physiology and pathophysiology.

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An Improved (Paraffin Section) Method for the Dopa Reaction

Cited by 64 publications

References 5 publications

Pathogenesis of diffuse melanosis secondary to malignant melanoma*

Pathogenesis of diffuse melanosis secondary to malignant melanoma*

Melanin and dopa-positive cells in the skin of tropical cattle

The Proteolytic Potential of Normal Human Melanocytes: Comparison With Other Skin Cells and Melanoma Cell Lines

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