Novel angiotensin-converting enzyme (ACE) inhibitory peptides derived from boneless chicken leg meat.

Four peptides that inhibit angiotensin-converting enzyme (ACE) were separated from the hydorlysate of boneless chicken leg meat digested with artificial gastric juice (pepsin). Two peptides were identified as the peptides encrypted in myosin heavy chain. The peptide P1 (MNVKHWPWMK) corresponds to the amino acid sequence from amino acids 825 to 834 of myosin heavy chain, and the peptide P4 (VTVNPYKWLP) corresponds to the amino acid sequence from amino acids 125 to 135 of myosin heavy chain. They are novel ACE inhibitory peptides derived from chicken, and IC(50) values of P1 and P4 were determined as 228 and 5.5 microM, respectively. Although these values were much larger than 0.022 microM for captopril, a typical synthetic ACE inhibitor, they are comparable to IC(50) values reported for various ACE inhibitory peptides derived from foods. Because the peptide P4 has a relatively low IC(50) value, it is a good starting substance for designing food supplements for hypertensive patients.

Establishment of a kit-negative cell line of melanocyte precursors from mouse neural crest cells.

We previously established a mouse neural crest cell line named NCCmelb4, which is positive for Kit and negative for tyrosinase. NCCmelb4 cells were useful to study the effects of extrinsic factors such as retinoic acids and vitamin D(3) on melanocyte differentiation, but in order to study the development of melanocytes from multipotent neural crest cells, cell lines of melanocyte progenitors in earlier developmental stages are needed. In the present study, we established an immortal cell line named NCCmelb4M5 that was derived from NCCmelb4 cells. NCCmelb4M5 cells do not express Kit and are immortal and stable in the absence of Kit ligand. They are positive for melanocyte markers such as tyrosinase-related protein 1 and DOPAchrome tautomerase and they contain stage I melanosomes. Interestingly, glial fibrillary acidic protein, which is a marker for glial cells, is also positive in NCCmelb4M5 cells, while NCCmelb4 cells are negative for this protein. Immunostaining and a cell ELISA assay revealed that 12-O-tetradecanoylphorbol 13-acetate (TPA) and cholera toxin (CT) induce Kit expression in NCCmelb4M5 cells. Real-time polymerase chain reaction analysis also demonstrated the induction of Kit mRNA by TPA and CT. Microphthalmia-associated transcription factor mRNA is simultaneously enhanced by the same treatment. Kit induced by TPA/CT in NCCmelb4M5 cells disappeared after the cells were subcultured and incubated without TPA/CT. These findings show that NCCmelb4M5 cells have the potential to differentiate into Kit-positive melanocyte precursors and may be useful to study mechanisms of development and differentiation of melanocytes in mouse neural crest cells.

Detection of human papillomavirus type 57 in the tissue of a plantar epidermoid cyst.

Plantar epidermoid cysts with human papillomavirus (HPV) infection are not rare in Japan. Most of them show the cytopathic effect of HPV type 60 - homogeneous intracytoplasmic inclusion bodies. Our case presented a plantar epidermoid cyst with vacuolation around the granular cell layer without any features of HPV type 60. In situ hybridization and polymerase chain reaction followed by DNA sequencing analysis revealed an association with HPV type 57.

Primary cutaneous T-cell-rich B-cell lymphoma in a zosteriform distribution associated with Epstein-Barr virus infection.

T-cell-rich B-cell lymphoma (TRBL) is a lately recognized B-cell lymphoma variant characterized by a minor population of neoplastic B cells existing in a background of predominant polyclonal T cells. We report an 86-year-old man with primary cutaneous TRBL associated with Epstein-Barr (EB) virus infection. Clinically, palpable scaly erythemas were distributed in a zosteriform pattern on the right abdomen. Histologically, massive cellular infiltrates were located in the upper- and mid-dermis. Higher magnification showed that the cellular infiltration was composed mainly of abnormal mononuclear, large lymphoid cells with clear cytoplasm and scattered mitoses and small lymphocytes, which represented in excess of 75% of all the infiltrating cells. Immunohistochemical staining revealed that the large cells were positive for the B cell marker, CD20, but negative for the T cell marker, CD3. On the other hand, the small cells were positive for CD3, but negative for CD20. Polymerase chain reaction (PCR) revealed EB virus DNA in the skin lesion. Primary cutaneous TRBL has only been reported in 15 cases worldwide. To our knowledge, this is the first case of primary cutaneous TRBL in a zosteriform distribution reported in the literature and the second case of primary cutaneous TRBL associated with the EB virus infection. We postulate that the EB virus may be a contributory pathogenetic event leading to monoclonal B-cell proliferation.

Differentiation of murine melanocyte precursors induced by 1,25-dihydroxyvitamin D3 is associated with the stimulation of endothelin B receptor expression.

The effects of 1,25-dihydroxyvitamin D3 on the differentiation of immature melanocyte precursors were studied. The NCC-/melb4 cell line is an immature melanocyte cell line established from mouse neural crest cells. 1,25-Dihydroxyvitamin D3 inhibited the growth of NCC-/melb4 cells at concentrations higher than 10(-8) m. That growth inhibition was accompanied by the induction of tyrosinase and a change in L-3,4-dihydroxyphenylalanine reactivity from negative to positive. Electron microscopy demonstrated that melanosomes were in more advanced stages after 1,25-dihydroxyvitamin D3 treatment. In primary cultures of murine neural crest cells, L-3,4-dihydroxyphenylalanine-positive cells were increased after 1,25-dihydroxyvitamin D3 treatment. These findings indicate that 1,25-dihydroxyvitamin D3 stimulates the differentiation of immature melanocyte precursors. Moreover, immunostaining and reverse transcription-polymerase chain reaction analysis revealed that endothelin B receptor expression was induced in NCC-/melb4 cells following treatment with 1,25-dihydroxyvitamin D3. The induction of endothelin B receptor by 1,25-dihydroxyvitamin D3 was also demonstrated in neural crest cell primary cultures, but not in mature melanocytes. The expression of microphthalmia-associated transcription factor was induced in NCC-/melb4 cells treated with 1,25-dihydroxyvitamin D3 and endothelin 3, but not by 1,25-dihydroxyvitamin D3 alone, suggesting that endothelin 3 may stimulate the expression of the microphthalmia-associated transcription factor gene after binding to the endothelin B receptor induced by 1,25-dihydroxyvitamin D3. These findings suggest a regulatory role for vitamin D3 in melanocyte development and melanogenesis, and may also explain the working mechanism of vitamin D3 in the treatment of vitiligo.