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Biomedical subjects

H Tagami

Publications and source records attributed to H Tagami.

At least 307 records · Page 17Linked to original sources
PubMed1988

Stimulation of human melanocytes by vitamin D3 possibly mediates skin pigmentation after sun exposure.

We found an increased amount of immunoreactive tyrosinase in human melanocytes after 6-d culturing with vitamin D3 (cholecalciferol). Most of these melanocytes became more dendritic and swollen in a fashion similar to that noted in the skin after ultraviolet irradiation. However, 7-dehydrocholesterol (pro-vitamin D3) or 1 alpha,25-dihydroxy-vitamin D3 (activated vitamin D3) were found to have little effect on the same system. Because vitamin D3 is known to be photochemically converted from pro-vitamin D3 in the skin by ultraviolet irradiation, the mechanism of human skin pigmentation after ultraviolet irradiation, thus far unknown, may be at least partly explained by this stimulating effect of vitamin D3 on melanocytes.

Cholecalciferol↗
PubMed1988

Subcutaneous sarcoidosis with extensive caseation necrosis.

We report a 24-year-old male patient with sarcoidosis who developed subcutaneous nodules on his thighs and buttocks at the sites of repeated intramuscular injections. Histologically, there were extensive areas of caseation necrosis surrounded by typical sarcoidal granuloma. The nodules regressed spontaneously over a period of 4 months, concurrently, both his bilateral hilar adenopathy and the results of immunological tests, returned to normal. We think that these lesions developed at the sites of subcutaneous scar tissue induced by frequent injections in childhood. We believe the pathomechanism to be similar to that for scar sarcoidosis, and that the extensive caseation necrosis reflected a regressing stage of the disease.

Adult↗
PubMed1988

Giant solitary sebaceous gland hyperplasia clinically simulating epidermoid cyst.

We report an unusual case of sebaceous gland hyperplasia manifested clinically as a large solitary intracutaneous nodule, which was at first diagnosed as an epidermoid cyst. Histologically, the nodule consisted of a single large central cavity connected with numerous fully-matured sebaceous glands. We discuss the unique clinical appearance and its histopathological differential diagnosis including sebaceous adenoma, sebaceous trichofolliculoma, organoid nevus and sebaceous gland hyperplasia.

Diagnosis, Differential↗
PubMed1988

Photosensitive psoriasis provoked by a suberythematous dose of ultraviolet-B light.

An unusual case of 'photosensitive psoriasis' is reported. This patient had experienced an exacerbation after sea-bathing, and psoriatic eruptions were observed on the sun-exposed areas of the body. Phototesting with ultraviolet-B (UV-B) revealed his minimal erythema dose to be within normal limits. Three to four weeks after phototesting, however, he developed a psoriatic macule on the area exposed to the suberythematous dose of UV-B. The histologic features of the skin lesion provoked by UV-B irradiation were similar to those of naturally occurring lesions on areas covered by clothes. Moreover, failure to reproduce skin lesions following tape-stripping ruled out a proneness of this patient to develop the Köbner phenomenon nonspecifically.

Adult↗
PubMed1988

Increased plasma concentrations of complement modulating proteins (C1 inhibitor, C4-binding protein, factor H and factor I) in psoriasis.

By using single radial immunodiffusion we measured the plasma levels of four complement modulating proteins, i.e., C1 inhibitor, C4-binding protein, factor H and factor I in 19 psoriatic patients in comparison with those of healthy controls. Except for C1 inhibitor which was only marginally elevated, they were found to be significantly increased in psoriatic patients. When psoriatic patients were classified into subgroups based on the clinical severity, the levels of factor H and those of factor I showed a close positive correlation with the activity and extent of the skin lesions, whereas such clear relationship could not be found with C1 inactivator or with C4-binding protein. These results offer additional support for the hypothesis that the complement system is involved in psoriasis.

Adult↗
PubMed1988

Stimulatory effect of histamine on normal human melanocytes in vitro.

Normal human epidermal melanocytes became swollen and more dendritic and the immunoreactive tyrosinase increased markedly when they were cultured for 2 days with 5 microM of histamine. These results suggest that high dermal concentrations of histamine may be responsible for the induction of skin pigmentary changes associated with local proliferation of mast cells such as in urticaria pigmentosa and systemic mastocytosis.

Cells, Cultured↗
PubMed1988

Absence of IL-1 inhibitor in psoriatic scale extracts.

In the previous report we found that IL-1-like activity in horny tissue extracts from patients with psoriasis vulgaris and related sterile pustular dermatoses was remarkably low as compared to that in orthokeratotic horny tissue extracts prepared from non-inflammatory skin. In this report we studied the inhibitory activity of lesional horny tissue extracts from three psoriatics on recombinant IL-1-induced thymocyte proliferation in order to search for a possible coexistence of substances which may inhibit thymocyte proliferation. However, we failed to demonstrate any remarkable IL-1 inhibitory activity in each fraction after gel filtration high-performance liquid chromatography of the psoriatic scale extracts or in that of extracts from the plantar callus. We conclude that IL-1 stores are decreased in the pathologic horny layers of psoriatic lesions.

Dose-Response Relationship, Immunologic↗
PubMed1988

Leukotrienes and thromboxane B2 stimulate normal human melanocytes in vitro: possible inducers of postinflammatory pigmentation.

Normal human epidermal melanocytes became swollen and more dendritic with an increase in the amount of immunoreactive tyrosinase when they were cultured for 2 days with each one of leukotriene (LT) C4, LTD4 and TXB2. Their effects were stronger than that of prostaglandin E2, about which we have previously reported. From these data we suggest that arachidonate-derived chemical mediators, especially LTC4, LTD4 and TXB2 may be responsible for the induction of post-inflammatory hyperpigmentation of the skin.

Cells, Cultured↗
PubMed1988

Molecular basis for the heterogeneity of human tyrosinase.

A cDNA clone, pHT gamma 1, representing human tyrosinase mRNA was isolated by screening a melanoma cDNA library with a synthetic oligonucleotide complementary to a segment of the human tyrosinase cDNA, Pmel 34 [Kwon et al. (1987) Proc. nat. Acad. Sci. USA 84, 7473-7477]. However, there are a number of differences in the nucleotide sequence between two cDNAs, pHT gamma 1 and Pmel 34, particularly in the region coding for the carboxyl terminus of the enzyme (putative exon 5). We therefore cloned the genomic DNA segment carrying the exon 5 of the human tyrosinase gene by screening a human placental genomic DNA library with a cloned cDNA probe. The nucleotide sequences of human tyrosinase cDNA as well as part of its gene were determined. Mature human tyrosinase is composed of 511 amino acids with a molecular weight of 58,000. We provide evidence for the presence of at least two species of human tyrosinase mRNA generated by alternative splicing in human pigmented melanoma cells.

Amino Acid Sequence↗
PubMed1988

Pustular irritant dermatitis due to croton oil. Evaluation of the role played by leukocytes and complement.

To elucidate the pathomechanisms of irritant pustular dermatitis and to evaluate the role of leukocytes in pustulation induced by croton oil, we compared the skin responses in leukopenic-and decomplemented guinea pigs with those in control saline-injected animals, to 1% croton oil application. Both decomplemented and control animals responded similarly to croton oil, showing erythema and pustulation at 24 h after topical application; microscopically numerous mononuclear and polymorphonuclear cells infiltrated the skin. Meanwhile, the clinical and histopathological response of leukopenic animals to croton oil was significantly depressed. Time-course study of inflammatory infiltrate in the dermis of controls revealed that mononuclear cells preceded the infiltration of polymorphonuclears. Although leukocytes constitute an important component in croton oil dermatitis, our results suggest that unclarified chemical mediators, other than complement-derived chemotactic factors, play a crucial role as a primary chemoattractant in the production of pustulation at the croton oil-applied site.

Administration, Cutaneous↗
PubMed1988

Acquired progressive lymphangioma as a flat erythematous patch on the abdominal wall of a child.

An erythematous patch was noted on the abdominal wall of an 8-year-old boy. The lesion showed a prolonged initial clinical course, followed by rapid later growth, finally reaching 3.7 X 7.0 cm in size over four years. Despite the harmless clinical appearance, the lesion was histologically characterized by tortuous vascular channels with some cellular atypia. Immunoperoxidase staining disclosed no factor VIII-related antigen or reaction to Ulex europaeus I lectin on tumor cells. There has been no recurrence three years after local excision. Although many features in our case resemble those reported in the literature under the term low-grade angiosarcoma, our preferred designation for such cases is acquired progressive lymphangioma, rather than angiosarcoma, because of their benign behavior.

Abdominal Muscles↗
PubMed1988

Immunohistologic studies in Schamberg's disease. Evidence for cellular immune reaction in lesional skin.

We studied eight cases of Schamberg's disease immunohistologically by using monoclonal antibodies. The dermal infiltrate was composed of Leu-1-reactive T cells, OKT6-reactive Langerhans' cells, and Leu-M5-reactive (Leu-M5+) macrophages. Among them, the major population consisted of T cells with the predominance of Leu-3a-reactive (Leu-3a+) T cells over Leu-2a-reactive (Leu-2a+) T cells. On the other hand, the epidermotropic mononuclear cells consisted of Leu-2a+ and Leu-3a+ T cells without any predominant pattern, and Leu-M5+ macrophages. Furthermore, note that a pemphiguslike intercellular staining pattern was observed in the epidermis in most of the cases, when the sections were stained either with anti-HLA-DR antibody or with OKT6, suggesting the HLA-DR antigen expression on the keratinocyte surface and possibly an enlargement of Langerhans' cells. Based on these immunohistologic findings, we think that Langerhans' cells play an important role in the pathomechanism of Schamberg's disease, and that cellular immune reactions are taking place in the lesional skin.

Adult↗
PubMed1987

Possible functional impairment of Langerhans' cells in vitiliginous skin. Reduced ability to elicit dinitrochlorobenzene contact sensitivity reaction and decreased stimulatory effect in the allogeneic mixed skin cell lymphocyte culture reaction.

We used patch testing to compare the ability to elicit contact sensitivity to dinitrochlorobenzene (DNCB) of uninvolved with vitiliginous skin of 31 patients with vitiligo. The induction of DNCB contact sensitivity was possible in the vitiliginous skin in the same way as in normal skin. The DNCB contact sensitivity reactions, however, were generally diminished in vitiliginous skin, although the number of cases showing similar DNCB contact reactivity between normal and vitiliginous skin increased when the sensitization procedure was performed in vitiliginous skin instead of normal skin. On the other hand, delayed skin reactions to intradermally injected Candida albicans antigen were not suppressed in vitiliginous skin. The number of Langerhans' cells was not decreased in vitiliginous skin as compared with that of normal skin. The epidermal cells derived from vitiliginous skin, however, tended to show a lower stimulatory effect in the allogeneic mixed skin cell lymphocyte culture reaction than those from normal skin. These results suggest a possibility of functional impairment of Langerhans' cells in vitiliginous skin.

Antigens, Fungal↗
PubMed1987

Leukocyte chemotactic properties of soluble horny contents in epidermal cysts.

Epidermal cysts are one of the most common tumors of the skin. Although asymptomatic ordinarily, they may sometimes become severely inflamed with massive invasion of polymorphonuclear leukocytes (PMN). We studied in vitro PMN chemotactic properties of the aqueous extract prepared from the horny material of epidermal cysts obtained from three patients. A crude aqueous extract of the horny content of the cysts showed PMN chemotactic activity, which, however, was less than that of a horny layer extract prepared from normal skin. Characterization of PMN chemotactic activity using a Sephadex G-75 column showed a peak in the low molecular weight fractions eluting between the vitamin B12 and phenol red markers, which corresponds with the peak of absorbance at 280 nm. The chemotactic substances withstood boiling and trypsin or protease digestion. Although the chemotactic activity was partially ether-extractable, the presence of leukotriene B4 was not demonstrated by radioimmunoassay. In addition to their own chemotactic activity, the horny extracts of epidermal cysts showed cytotaxigenic properties in the presence of fresh serum.

Adult↗
PubMed1987

Functional analysis of Ia antigen-bearing keratinocytes: mixed skin lymphocyte culture between Ia antigen-bearing Pam 212 cells and allogeneic and syngeneic splenic T cells.

Keratinocytes express Ia antigens in various skin disorders, although the biological role of these Ia antigen-bearing (Ia+) keratinocytes remains unclear. We induced Ia antigens on Pam 212 murine keratinocyte cell line by interferon-gamma(IFN-gamma) and using these cells, we performed the mixed skin lymphocyte culture with syngeneic BALB/c or allogeneic C3H/He splenic T cells. Unexpectedly, Pam 212 cells were found to stimulate both syngeneic and allogeneic T cells irrespective of IFN-gamma treatment. However, both syngeneic and allogeneic T cells cultured with IFN-gamma-treated Pam 212 cells incorporated [3H]thymidine much more actively than those cultured with IFN-gamma-untreated Pam 212 cells. This stimulation was not inhibited by monoclonal anti-I-Ad antibody. Analysis of the responding T cells demonstrated that the syngeneic T-cell stimulation by IFN-gamma-treated Pam 212 cells occurred in both purified Lyt 1-T cells and Lyt 2- T cells. Furthermore, we found that the T cells cultured with the IFN-gamma-treated cells were composed of two morphologically different types of cells. Determination of their surface phenotype showed that the small cell population consisted of 57% Thy-1+, 23% Lyt-1+, 6% Lyt-2+, and 9% asialo-GM1+ cells, while the large cells consisted of 53% Thy-1+, 15% Lyt-1+, 9% Lyt-2+, and 24% asialo-GM1+ cells. These findings suggest that IFN-gamma-treated Pam 212 cells could stimulate more than one kind of splenic T cell populations.

Animals↗