Possible involvement of proteolytic degradation of tyrosinase in the regulatory effect of fatty acids on melanogenesis

The purpose of this study was to investigate the mechanism of fatty acid-induced regulation of melanogenesis. An apparent regulatory effect on melanogenesis was observed when cultured B16F10 melanoma cells were incubated with fatty acids, i.e., linoleic acid (unsaturated, C18:2) decreased melanin synthesis while palmitic acid (saturated, C16:0) increased it. However, mRNA levels of the melanogenic enzymes, tyrosinase, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2), were not altered. Regarding protein levels of these enzymes, the amount of tyrosinase was decreased by linoleic acid and increased by palmitic acid, whereas the amounts of TRP1 and TRP2 did not change after incubation with fatty acids. Pulse-chase assay by [35S]methionine metabolic labeling revealed that neither linoleic acid nor palmitic acid altered the synthesis of tyrosinase. Further, it was shown that linoleic acid accelerated, while palmitic acid decelerated, the proteolytic degradation of tyrosinase. These results suggest that modification of proteolytic degradation of tyrosinase is involved in regulatory effects of fatty acids on melanogenesis in cultured melanoma cells.

[Role of Candida allergen in atopic dermatitis and efficacy of oral therapy with various antifungal agents]

We studied whether fungal allergens play a role in exacerbating the clinical symptoms of atopic dermatitis (AD). We found that the percentage of the patients who showed CAP-RAST positive (2 < or = score) to Candida albicans (Ca) was significantly higher in the patients with severe symptoms and high serum IgE level than those with mild symptoms and lower IgE. This was also true for the patients with CAP-RAST positive to Pityrosporum ovale (Po). AD patients with their symptoms localized to head and neck showed significantly higher tendency to have positive CAP-RAST (2 < or = score) to Ca and Po when compared to those with their eruption distributing to the extremities. We then evaluated the efficacy of oral therapy with antifungal agents in 140 cases of refractory AD with positive CAP-RAST to Ca. Good or excellent response was obtained in 60% with fluconazole, 35% with itraconazole, 31% with amphotericin B, 28% with nystatin. The present finding that amphotericin B and nystatin, both of which are not absorbed through intestine, were effective for approximately a third of the patients indicates that Ca in the intestine plays an important role in triggering AD symptoms. Fluconazole was more effective than amphotericin B and nystatin, suggesting that fungal colonizing in other parts of the body but the digestive tract also play a role in the exacerbation of AD symptoms.

The depigmenting effect of alpha-tocopheryl ferulate on human melanoma cells

Oral vitamin E (alpha-tocopherol, alpha-T) supplementation has been reported to improve facial hyperpigmentation. alpha-Tocopheryl ferulate (alpha-TF) is a compound of alpha-T and ferulic acid connected by an ester bond; ferulic acid is also an antioxidant, and could scavenge free radicals induced by ultraviolet (UV) radiation, and thus maintain the long-lasting antioxidative effect of alpha-T. Our aim was to see whether alpha-TF might be useful as a whitening agent and an antioxidant to improve and prevent facial hyperpigmentation following UV exposure. In this study, the inhibitory effect of alpha-TF on melanogenesis was examined biochemically using human melanoma cells in culture. The results show that alpha-TF, solubilized in ethanol or in 0.5% lecithin, inhibited melanization significantly, as did alpha-T at a concentration of 100 microg/mL, without inhibiting cell growth. This phenotypic change was associated with inhibition of tyrosinase and 5, 6-dihydroxyindole-2-carboxylic acid polymerase activities, and the degree of inhibition was dose dependent. No significant effect on DOPAchrome tautomerase activity was observed. alpha-TF did not directly inhibit tyrosinase activity of the large granule fraction extracted from human melanoma cells, and Western blotting revealed that there were no changes in protein content or in molecular size of tyrosinase, tyrosinase-related protein (TRP)-1 or TRP-2. Therefore, the inhibition of tyrosinase activity by alpha-TF might be due to effects at the post-translational level, and possibly by a secondary molecule activated by alpha-TF. These results suggest that alpha-TF is a candidate for an efficient whitening agent which suppresses melanogenesis and inhibits biological reactions induced by reactive oxygen species.

Effect of stress on atopic dermatitis: investigation in patients after the great hanshin earthquake

BACKGROUND

Although a variety of factors are responsible for atopic dermatitis (AD), very little is known about the effect of stress caused by a natural disaster on AD symptoms.

OBJECTIVE

This study was conducted to assess the effect of stress or trauma on the symptoms of AD.

METHODS

One thousand four hundred fifty-seven patients with AD (745 males and 712 females), diagnosed by using the criteria of the Japanese Dermatology Association, were enrolled in the study. The data were obtained from a self-administered questionnaire given to patients with AD after experiencing the Great Hanshin Earthquake. The data were analyzed by multivariate logistic regression analysis. Patients were divided into 3 groups: area A, severe damage to buildings and houses; area B, mild damage; and control area, no damage.

RESULTS

Exacerbation of skin symptoms was found in 38% and 34% of patients in areas A and B, respectively, whereas similar exacerbation was seen in 7% of control patients. Nine percent and 5% of the patients in areas A and B, respectively, showed improvement in their symptoms compared with 1% in the control group. The earthquake caused stress in 63% and 48% of the patients in areas A and B, respectively, but fewer patients felt stress in undamaged areas (19%). Multiple logistic regression analysis revealed that of the factors examined here, subjective distress is the factor that is most responsible for the exacerbation of skin symptoms (odds ratio, 2.98; 95% confidence interval, 2.25-3.96).

CONCLUSION

The results presented here strongly suggest that stress caused by a natural disaster influences AD symptoms.

Higher susceptibility to apoptosis following ultraviolet B irradiation of xeroderma pigmentosum fibroblasts is accompanied by upregulation of p53 and downregulation of bcl-2

Apoptosis plays an important part as a defence mechanism in eliminating damaged cells. Among the complex factors which regulate apoptosis, the p53 tumour suppressor protein which is induced by DNA damage has been suggested to play a crucial part. Cells from xeroderma pigmentosum (XP) patients, which are defective in nucleotide excision repair, express higher levels of p53 and are highly susceptible to cell death after ultraviolet (UV) irradiation. To examine the relationships between DNA damage, p53 and apoptosis, normal and XP group A fibroblasts were exposed to UVB, and expressions of molecules involved in apoptosis were examined. Apoptosis of XP and normal cells was clearly detected at 48 h after irradiation with UVB at doses of 5 and 40 mJ/cm2, respectively. Cells were positive by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) staining under these exposure conditions. At 6 h after irradiation, p53 protein expression was induced in normal and XP cells at minimal doses of 10 and 2.5 mJ/cm2, respectively. Bcl-2 protein, an inhibitor of apoptosis, was downregulated prior to cell death following UVB exposure at doses that induced apoptosis in both cell types. These results suggest that DNA damage due to UVB induces apoptosis by upregulating proapoptotic molecules such as p53, and by downregulating anti-apoptotic molecules such as Bcl-2.

Horizontal and vertical pigment spread into surrounding piebald epidermis and hair follicles after suction blister epidermal grafting

Following the earlier description of Carnot and Deflandre in 1896, pigment spread phenomenon in mammals was investigated using immunogenetically marked melanocytes (Billingham and Silver, Quart. Rev. Biol. 1960 35: 1-40; Billingham and Silver, Ann. N.Y. Acad. Sci. 1963 100: 348-363). In spite of a number of similar studies on vitiligo lesions, detailed evaluation of pigment spread in piebald lesions has not been reported. To gain further insight into the pigment spread phenomenon in human skin, five piebald patients were studied, on whom suction blister epidermal grafting therapy onto piebald patches was performed. In the present study, pigmentation of all epidermal grafts from normally pigmented areas spread horizontally. It was also found that pre-existing white hairs in recipient sites became pigmented within 1 year after epidermal grafting. Immunofluorescence studies using melanocyte-specific antibody NKI/beteb revealed the newly induced presence of melanocytes in the newly pigmented hair follicles. Further, to study the possible mechanisms inhibiting melanocyte migration from normal skin into piebald lesions, epidermis was grafted from border zones (containing both normal and piebald skin) into the center of hypopigmented lesions. Melanocytes clearly migrated through the border zone of grafted epidermis into surrounding recipient hypopigmented sites.

Enhanced expression of melanocortin-1 receptor (MC1-R) in normal human keratinocytes during differentiation: evidence for increased expression of POMC peptides near suprabasal layer of epidermis

Immunohistochemical staining of human skin specimen showed the stronger localization of proopiomelanocortin peptides near the suprabasal layer of the epidermis, where keratinocytes are mostly differentiated. To test the possibilities of whether the production of proopiomelanocortin peptides or their receptor-binding activity or both is increased during differentiation of keratinocytes, we treated the cells in culture with Ca2+ to induce their differentiation. The production of proopiomelanocortin peptides and its gene expression were not induced significantly, but the binding ability of melanocortin receptor, as well as its gene expression were stimulated by Ca2+. Ultraviolet B irradiation, an inducer of differentiation, stimulated both proopiomelanocortin production and melanocortin receptor expression. These data show that normal human keratinocytes express melanocortin receptor similar to melanocytes, and that it is induced during differentiation.

Skin cancer screening in Okinawa, Japan

Depletion of the ozone layer has been observed on a global scale. Ozone depletion increases the amount of biologically harmful solar ultraviolet radiation (UV) that reaches the surface of the Earth, leading to an increased incidence of skin cancer. We previously reported the prevalence and incidence of actinic keratosis (AK) in Kasai City, which is located almost at the center of Japan. To evaluate the effects of different ambient annual UV doses on the prevalence and incidence of non-melanoma skin cancer and AK in Japan, we screened for skin cancer on Ie Island in Okinawa at the southern end of Japan, where the annual cumulative dose of UV is assumed to be the highest in Japan. The island had a population of 5562 in 1993. A prospective 4-year population-based study on the prevalence and incidence of cutaneous neoplasms was conducted by examining the sun-exposed skin of people over 40 years of age living on Ie Island. In 1993 1996, 86 cases of AK, nine of basal cell carcinoma (BCC), and two of squamous cell carcinoma were identified. The annual prevalence of AK on Ie Island was 1159.4 in 1993, 572.8 in 1994, 1014.3 in 1995 and 988.9 per 100000 Japanese in 1996. These values were significantly higher than those in Kasai City. The annual age-adjusted odds ratios for AK of Ie Island to Kasai City were 2.79, 1.38, 2.45 and 2.39, respectively. The incidences of AK on Ie Island per 100,000 were 637.0 in 1995 and 625.5 in 1996, which were also significantly higher than those in Kasai City (223.6 in 1993 and 171.2 in 1994). The prevalence of BCC was 123.6 and the incidence was 26.1. Together with our previous reports, the present results show a possible inverse relationship between the prevalence and incidence of AK and latitude among Japanese people.

Induced expression of p16 and p21 proteins in UVB-irradiated human epidermis and cultured keratinocytes

It has been suggested that p16INK4a, the product of the cyclin-dependent kinase inhibitor 2 or multiple tumor suppressor 1 gene, prevents phosphorylation of the retinoblastoma gene product, and thus acts as a negative cell cycle regulator. To elucidate an effect of ultraviolet B (UVB) radiation on p16 expression and its relation to p21, and proliferating cell nuclear antigen (PCNA), immunohistochemical and western blot analyses were performed on UVB-irradiated normal human epidermis and cultured keratinocytes, respectively. Little p16 protein was seen in the control epidermis or keratinocytes. Increases in the levels of p16 protein in both UVB-irradiated epidermis and keratinocytes occurred in a similar manner, in which p16 was induced at 24-48 h and peaked at 72-120 h after irradiation. The induced expression of p21 was observed relatively earlier than that of p16, with peaked expression at 24-48 h and a return to control level by 168 h. PCNA expression was increased slightly until 48 h but significantly increased during 48-168 h of post-irradiation with peak expression at 72 h. These results indicate that together with p21, p16 protein may play an important role for protective or adaptive response to UVB exposure of human skin.

A case of multiple sebaceous epithelioma: analysis of microsatellite instability

Sebaceous gland tumor is a rare disease that is a sign of Muir-Torre syndrome, an autosomal, dominantly inherited genodermatosis characterized by the presence of at least one sebaceous gland tumor and a minimum of one internal malignancy. Recent studies have indicated that defective DNA mismatch repair occurs in Muir-Torre syndrome. Cutaneous lesions may occur before diagnosis of the internal cancer. We describe a 64-year-old male patient with multiple sebaceous epitheliomas with no evident internal malignancy. Microsatellite instability, determined by examining dinucleotide CA repeats at the microsatellite loci, was observed in DNA from one sebaceous epithelioma but not from the other two sebaceous epitheliomas or from one basal cell epithelioma with sebaceous differentiation, suggesting that this condition is unlikely to be due to germ-line mutation of mismatch repair genes.

Pharmacokinetics of 10B-p-boronophenylalanine in tumours, skin and blood of melanoma patients: a study of boron neutron capture therapy for malignant melanoma

To optimize the neutron dose for boron neutron capture therapy (BNCT), the boron-10 (10B) concentration kinetics of 10B-p-boronophenylalanine (BPA) were analysed in 22 melanoma patients with primary or metastatic melanomas who received BPA and subsequently underwent BNCT or surgery. The blood concentration in nine patients receiving 179.7+/-14.9 mg/kg BPA increased with time during intravenous infusion, peaked at the end of administration and decreased thereafter. The peak values at the end of administration were 9.4 2.6 microg 10B/g blood, and half-lives for the initial and second components of the blood clearance were 2.8 and 9.2 h, respectively. Skin concentrations in the 10 patients varied from case to case; however, skin-to-blood ratios were relatively constant at 1.31+/-0.22 during the 6 h after the end of administration. Boron concentrations in the tumours resected from the seven patients who were operated on decreased in parallel to the blood values, the tumour-to-blood ratio being relatively constant at 3.40+/-0.83. The present analytical data of BPA pharmacokinetics support our previous approach for optimizing the timing of irradiation and setting the neutron flux large enough for tumour eradication but still tolerable for normal skin.

Overexpression of the human homologue of Drosophila patched (PTCH) in skin tumours: specificity for basal cell carcinoma

The human homologue of the Drosophila segment polarity gene patched (PTCH) has been identified as the gene for the naevoid basal cell carcinoma (BCC) syndrome and has also been shown to be mutated in sporadic BCC. In order to elucidate the specificity of the PTCH abnormality in BCC, we examined normal skin and 12 BCC and 24 other types of tumour from Japanese patients for expression of the PTCH transcript by competitive reverse transcription-polymerase chain reaction, as mutational inactivation of PTCH leads to overexpression of the mutant transcript owing to failure of a negative feedback mechanism. We found a high level of PTCH expression in all 12 BCCs, while 23 of the other tumours and four specimens of normal skin showed no or weak expression of the gene, with the exception of one specimen from a patient with Bowen's disease which had high expression. These results indicate that the PTCH abnormality plays a critical role in the pathogenesis of BCC.

High levels of 8-hydroxy-2'-deoxyguanosine appear in normal human epidermis after a single dose of ultraviolet radiation

Major photoproducts induced by carcinogenic ultraviolet (UV) radiation are the cylobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts (6-4 PPs). 8-Hydroxy-2 -deoxyguanosine (8-OHdG) is also a DNA base-modified product generated by reactive oxygen species in conditions of ultraviolet stress, Although UVB-induced CPDs and 6-4 PPs have been investigated in animal and human skin, little is known about the role of 8-OHdG in UVB-induced human skin damage or carcinogenesis. Normal human skin from three volunteers was exposed to UV radiation, and the time course of induction and removal of 8-OHdG was examined by immunohistochemical analysis with catalysed signal amplification on formalin-fixed paraffin sections. Formation of CPDs and 6-4 PPs was also examined by immunostaining on the same skin specimens. Control epidermis with no exposure to UV radiation showed little nuclear staining of 8-OHdG, but an increased level of 8-OHdG was clearly observed in epidermis biopsied after irradiation. Induced 8-OHdG can rapidly be removed from nucleus during the first 24-48 h, as the staining intensity diminished gradually, almost reaching the control level by 72-96 h after irradiation. Staining for CPDs or 6-4 PPs revealed induction of these photoproducts in human skin, although 6-4 PP-positive cells disappeared more rapidly than those that stained for CPDs or 8-OHdG. Together with protective effect of antioxidants, our results indicate that not only CPDs and 6-4 PPs but also 8-OHdG may play a significant part in UV carcinogenesis.

UVA-induced immune suppression through an oxidative pathway

Although ultraviolet B (UVB) irradiation induces local immune or systemic immune suppression, depending on the dose, the immune suppression by ultraviolet A (UVA) has not been fully investigated. In this study, we investigated the effect of UVA on the immune response in vitro and in vivo. The effect of UVA on the antigen-presenting function of epidermal cells was measured in terms of antigen-specific T cell proliferation. A murine epidermal cell suspension was exposed to UVA in vitro, pulsed with trinitrobenzenesulfonic acid, and cultured with T cells prepared from syngeneic mice previously sensitized with trinitrochlorobenzene. UVA (5-20 J per cm2) suppressed the antigen-presenting function of epidermal cells in a dose-dependent manner, accompanied with suppression of the expression of costimulatory molecules on Langerhans cells. In order to investigate the effect of an antioxidant on the immune suppression, an epidermal cell suspension was irradiated with UVA in the presence or absence of glutathione. The suppressions of antigen-presenting function and ICAM-1 expression were significantly prevented by glutathione in a dose-dependent manner. Further, the effect of UVA on the immune response at the induction phase of contact hypersensitivity was evaluated in terms of lymph node cell proliferation ex vivo. UVA irradiation suppressed the endogenous proliferation of lymph node cells in trinitrochlorobenzene-painted mice, and this suppression was significantly reversed by the application of glutathione to the skin during irradiation. These results suggest that UVA-induced immune suppression may be mediated by reactive oxygen species, at least in part.

IL-12 promotes the accessory cell function of epidermal Langerhans cells

The objective of this study was to investigate the effects of cytokines regulating cutaneous immune responses, on the accessory cell function of epidermal cells (EC). EC were treated with various cytokines, and the accessory cell function of the cytokine-pretreated EC was examined by the allogeneic mixed epidermal cell-lymphocyte reaction (MECLR). Among the cytokines examined, IFN-gamma- and IL-12-pretreated EC augmented IFN-gamma production in the MECLR, while none of the other cytokines was effective. However, the cytokine-pretreated EC did neither affect T cell proliferation nor IL-4 production in the MECLR. Next we attempted to analyze the mechanisms by which IL-12-pretreated EC increase IFN-gamma production in the MECLR. Endogenous IFN-gamma produced during the IL-12 pretreatment of EC was found to play only a minor role in modulating the function of EC. The expression of MHC class II, CD80 and CD86 on EC was not affected by IL-12. On the other hand, soluble mediators that induce IFN-gamma production during the MECLR containing IL-12-pretreated EC were identified as endogenously produced IL-12 (the major mediator) and IL-18 (the minor mediator). Furthermore, the results of depletion experiments indicate that IL-12 promotes the accessory cell function of Langerhans cells to responder T cells in inducing IFN-gamma production in the MECLR.

Effect of arbutin on melanogenic proteins in human melanocytes

The inhibitory effect of arbutin, a naturally occurring beta-D-glucopyranoside derivative of hydroquinone, on melanogenesis was studied biochemically by using human melanocytes in culture. Cells were cultured in the presence of different concentrations of arbutin. The maximum concentration of arbutin that was not inhibitory to growth of the cells was 100 micrograms/ml. At that concentration, melanin synthesis was inhibited significantly by approximately 20% after 5 days, compared with untreated cells. This phenotypic change was associated with the inhibition of tyrosinase and DHICA polymerase activities, and the degree of inhibition was dose dependent. No significant difference in DOPAchrome tautomerase (DT) activity was observed before or after arbutin treatment. Western blotting experiments revealed there were no changes in protein content or in molecular size of tyrosinase, TRP-1 or TRP-2, indicating that inhibition of tyrosinase activity by arbutin might be due to effects at the post-translational level.

Modulation of melanocyte-stimulating hormone receptor expression on normal human melanocytes: evidence for a regulatory role of ultraviolet B, interleukin-1alpha, interleukin-1beta, endothelin-1 and tumour necrosis factor-alpha

Melanocyte-stimulating hormone (MSH) receptor binding activity and melanocortin-1 receptor (MC1-R) gene expression on normal human melanocytes have been studied as responses to the effects of ultraviolet B (UVB), interleukin-1 (IL-1), endothelin-1 (ET-1) and tumour necrosis factor-alpha (TNF-alpha), which are known as UV sensitive regulators of melanocytic function. MSH receptor (MSH-R) binding activity was upregulated by UVB, IL-1alpha, -1beta and ET-1, but was downregulated by TNF-alpha. Northern blot analysis showed that MC1-R mRNA expression was induced 24 h after UVB irradiation in a dose-dependent manner, and that 24-h treatment with ET-1 also induced an expression of MC1-R mRNA, whereas TNF-alpha downregulated the expression. In addition, IL-1alpha and -1beta have a small but real inductive effect on MC1-R mRNA expression. Taken together, our results suggest a model in which higher MC1-R mRNA expression is accompanied by upregulation of MSH-R binding activity, and enhanced by UVB or cytokines sensitive to UVB. Such a regulatory system would enable normal human melanocytes to respond to MSH more efficiently and induce an increase of melanization of the skin through the MSH/MSH-R system after UVB radiation.

Linoleic acid and alpha-linolenic acid lightens ultraviolet-induced hyperpigmentation of the skin

This study was conducted to evaluate the effects of unsaturated fatty acids on ultraviolet-induced hyperpigmentation of the skin. An efficient lightening effect was observed following topical application of linoleic acid or alpha-linolenic acid to UV-stimulated hyperpigmented dorsal skin of brownish guinea pigs. The number of melanocytes in the treated skin was similar to the number in the skin of the pigmented control, indicating that the pigment-lightening effect was not due to depletion of melanocytes. In vitro experiments using cultured murine melanoma cells showed that melanin production was inhibited most effectively by alpha-linolenic acid, followed by linoleic acid and then by oleic acid. Furthermore, the turnover of the stratum corneum, which plays an important role in the removal of melanin pigment from the epidermis, was accelerated by linoleic acid and by alpha-linolenic acid. Taken together, the results suggest that the pigment-lightening effects of linoleic acid and alpha-linolenic acid are, at least in part, due to suppression of melanin production by active melanocytes, and to enhanced desquamation of melanin pigment from the epidermis.

Immunoreactivity of alpha-melanocyte-stimulating hormone, adrenocorticotrophic hormone and beta-endorphin in cutaneous malignant melanoma and benign melanocytic naevi

Melanocyte-stimulating hormone (MSH) has been reported to enhance the experimental metastatic behaviour of melanoma cells in the mouse model. alpha-MSH production and MSH receptor (melanocortin 1 receptor gene) expression have been detected in cultured normal human melanocytes and metastasized melanomas. The exact role of MSH in the metastatic behaviour of human melanoma cells is, however, not yet known. To clarify a possible role of proopiomelanocortin (POMC)-derived peptides, including alpha-MSH, in melanoma development and progression, we analysed immunohistochemically the localization of alpha-MSH adrenocorticotrophic hormone (ACTH) and beta-endorphin in various kinds of benign pigmented naevocytic lesions and malignant melanomas. Three of 21 samples of common and dysplastic naevi showed detectable alpha-MSH staining in naevus cells, and five and six of 15 samples were weakly positive for ACTH and beta-endorphin staining, respectively. In melanoma samples, 24 of 45, 23 of 39 and 30 of 42 samples showed positive staining with alpha-MSH, ACTH and beta-endorphin antibodies, respectively. Furthermore, staining for all three antibodies was noted to be more intense and diffuse in samples of nodular melanoma, vertically growing acral lentiginous melanoma and superficial spreading melanoma as well as metastatic lesions compared with those of naevi. Although it is yet to be determined whether or not this strong staining for POMC-derived peptides in advanced melanoma cells indicates a role of autocrine or paracrine regulation, our results suggest a possible involvement of POMC gene products in melanoma progression.

Tissue distribution of a melanoma-associated antigen D-1 immunogenic in patients with melanoma

A human melanoma-associated antigen D-1 was recently identified by screening an expression cDNA library derived from mRNA of cultured melanoma cells with sera of melanoma patients. The aim of this study is to present in vivo expression and precise distribution of D-1 in normal tissues and benign or malignant neoplasms. By in situ hybridization, we found that the D-1 mRNA was exclusively expressed in the cytoplasms of melanoma cells, but not in keratinocytes, fibroblasts and lymphocytes adjacent to melanoma nests. Further immunohistochemical studies revealed that the expression of D-1 antigen was distributed to both the surface and cytoplasm of melanoma cells, indicating that D-1 antigen can be recognized by killer T lymphocytes or antibodies in vivo. No significant mRNA nor peptide of D-1 was detected in basal cell carcinoma, squamous cell carcinoma and other benign tumors such as melanocytic nevi and seborrheic keratosis. We also confirmed that D-1 mRNA and peptide were not expressed in normal organs by dot blot hybridization and western blot analysis, respectively. These results will assess the suitability of recombinant D-1 protein to implement active specific immunotherapy against melanoma.

Dermatomyofibroma (Plaqueförmige Dermale Fibromatose)

We reported a patient with dermatomyofibroma and reviewed the literature to characterize the immunohistochemical features of dermatomyofibroma. A 25-year-old woman presented with an asymptomatic, well-circumscribed, red-brown plaque on the left posterior shoulder. Microscopic examination revealed a non-encapsulated but well-circumscribed tumor in the mid-dermis extending into the upper subcutaneous fatty tissue. The tumor was composed of faintly eosinophilic, thin, wavy collagen fibers arranged as intersecting fascicles with an arrangement predominantly parallel to the skin surface. Embedded among the wavy fibers, there were a fair number of nuclei that were elongated, vesicular, and uniform in size. Immunohistochemical studies using a peroxidase-antiperoxidase technique disclosed that the cytoplasm of the tumor cells was positive for muscle actin. The tumor cells were negative for alpha-smooth muscle actin, desmin, factor XIIIa, S-100 protein, and CD34. Clinical, histopathologic, and immunohistochemical analysis confirmed dermatomyofibroma.

Incidence of actinic keratosis of Japanese in Kasai City, Hyogo

We determined the incidence of actinic keratosis (AK) among Japanese by screening for skin cancer in Kasai City, Hyogo, Japan, between 1993 and 1995. The incidence per 100,000 Japanese residents was 223.6 in 1993 and 171.2 in 1994. The prevalence of AK was 291.2 per 100,000 residents in 1993, 203.7 in 1994, and 86.8 in 1995. The prevalence in people who had more than six seborrheic keratoses on sun-exposed body sites and in people who had experienced severe sunburns with blister formation during childhood were significantly higher. These results indicate that more than six seborrheic keratoses and several episodes of blister formation in childhood may be risk factors for AK in the Japanese.

Prevalence of actinic keratosis in Japan

Most of the epidemiological studies on skin cancer that have been conducted to date have addressed the incidence in light-skinned Caucasians. To determine the prevalence rate of skin cancer and actinic keratosis (AK) on sun-exposed body sites of Japanese in Japan, we examined the skin of 4736 people during health examinations. The study was undertaken in Kasai City, Japan, which had a population of 52,837 in 1992, where participants in a regional health examination were seen by dermatologists. The final diagnosis was made histopathologically. Participants were also interviewed by means of a questionnaire. A total of 36 cases of AK and two of basal cell carcinoma were identified, to give a prevalence of 413.4 per 100,000 for AK. The prevalence among outdoor workers was significantly higher than that of indoor workers. Furthermore, when the participants were classified into three Japanese skin types, the prevalence of AK among people of skin Type I, who are sensitive to UV irradiation, was significantly higher than that among people of skin Types II and III, who are less sensitive.