Toshiaki Noda

The Relationship among Minimal Erythema Dose, Minimal Delayed Tanning Dose, and Skin Color

The relationship among minimal erythema dose (MED), minimal delayed tanning dose (MDTD), and skin color was examined in 16 healthy volunteers using three different spectra. The subjects were exposed to UVB, UVA+B, and UV+Visible light (UV+Visible) with a xenon arc solar simulator as a light source. The MEDs for UVB and UVA+B were less than the MDTDs, whereas the MED for UV+Visible was higher than the MDTD. There was no significant correlation between the MED and the MDTD for UVB or UVA+B. The MED for UV+Visible was significantly correlated to the MDTD (p<0.01). Skin color significantly correlated with MEDs for UVB and UVA+B (p<0.01), but not for UV+Visible. There was no significant correlation between skin color and the MDTD for any spectra. From these results, it is suggested that the relationship between erythemal and melanogenic responses is dependent on spectral bands of the light source and that skin color is a predictor of UV‐induced erythema.

Tissue response in sporotrichosis: light and electron microscopy studies

Summary. On the basis of electron microscopy examination of human tissue affected by sporotrichosis, we have proposed a classification, at the light microscopy level, of fungal cells in tissue. Light and electron microscopy observations clarified the following five points: (1) in sporotrichosis lesions in man, the fungal cells are frequently phagocytized by polymorphonuclear leucocytes (PMNs); (2) phagocytosis of phagocytes by other phagocytes was common, and giant cells phagocytized both fungal cells and PMNs; (3) fungal cells in the tissues of lesions were thought to be highly viable, and their budding was frequently observed within macrophages and giant cells; (4) it was highly probable that PMNs participated in asteroid body formation; (5) few free fungal cells were present in the tissues. We believe that the classification of fungal cells in sporotrichosis tissue into the five categories below is useful for correctly understanding the pathological condition in a sporotrichosis lesion: (1) fungal cells in PMNs, (2) fungal cells in PMNs within macrophages, (3) fungal cells in macrophages, (4) fungal cells in giant cells, and (5) free fungal cells.

The Relationship of Sun Protection Factor to Minimal Erythema Dose, Japanese Skin Type, and Skin Color

The relationship of sun protection factor (SPF) to minimal erythema dose (MED), Japanese skin type, and skin color was investigated on the unexposed backs of 48 healthy subjects. SPF of a UVB‐sunscreen was determined using sun lamps as a light source. A significant correlation was found between SPF and MED; subjects with lower MED showed higher SPF. The average SPF decreased with increasing skin type. There was no significant correlation between SPF and skin color (L*a*b* color system).

The Comparison of Sun Protection Factor Values with Different Light Sources

Sun protection factors (SPFs) were evaluated with three light sources (sunlight, a xenon arc solar simulator, and fluorescent lamps) in indoor and outdoor studies. Two types of light, UV‐A+B and UV+Visible, were obtained from the solar simulator. The untanned backs of twenty‐four healthy male volunteers were used as test sites. A broad spectrum sunscreen containing SPF 6, according to the manufacturer, was used. The sunscreen tested was applied at 2 mg/cm2. The actual SPF values were 4.8 with sunlight, 6.0 with UV‐A+B, 4.9 with UV+Visible, and 11.8 with fluorescent lamps. There were no significant differences between the SPF values with sunlight and those with the solar simulator; the SPF value for fluorescent lamps was significantly higher. The SPF with UV‐A+B of the solar simulator was similar to that with sunlight; the use of this light served to reduce pain on tested subjects. Therefore, UV‐A+B from the solar simulator seems to be the most appropriate artificial light source for evaluating sunscreens.

Skin Typing, Sun Exposure, and Sunscreen Use in a Population of Japanese

Distribution of Japanese skin types (JSTs), sun‐exposure habits, and sunscreen use were surveyed in 379 new outpatients. The largest number of subjects belonged to JST class J‐II (65%), J‐I was second (24%), and J‐III was third (11%). Eighty‐eight percent of those studied had occasional or habitual sun exposure during the summer, and many were exposed for more than three hours per exposure day (80% of those with occasional exposure; 62% of those with habitual exposure). More younger persons had occasional sun exposure than older persons. More males had habitual sun exposure than females. Sunscreens were used by 41% of the subjects, but 77% of these used them without accurate understanding of the definition of the sun protection factor. More J‐I subjects used sunscreens than J‐II and J‐III subjects. More females than males used them.

Inhibition Spectra of Solar Urticaria: A Case Report and a Review of the Japanese Cases

A 34‐year‐old Japanese female with solar urticaria is described, who had an episode of urticarial response when she was exposed to indoor fluorescent light first and sunlight later. The action spectrum was found to range from 480 to 520 nm with an inhibition spectrum above 650 nm in the visible light by both postirradiation and preirradiation. Injection of in vitro‐irradiated serum did not produce an urticarial wheal on the patient. In the Japanese literature, 17 cases of solar urticaria with inhibition spectra have been reported. The wavelength of the inhibition spectrum was longer than that of the action spectrum in each case.

Reproduction of the Skin Lesions of Polymorphous Light Eruption: A Case Report and a Review of the Japanese Literature

A case of polymorphous light eruption with plaque‐type lesions is reported. A 55‐year‐old male had pruritic erythemas and plaques on the head, the face, the nape, the back of the hands, and the left loin within days following sun exposure. The patients minimal erythema dose (MED) (60 mJ/cm2) of sunlamp irradiation for ultraviolet (UV) B was normal. Three once‐daily exposures to 2 MED of UVB (Epsteins repeat phototest technique) produced pruritic papules with a similar microscopic appearance to that of the patients skin lesion, indicating that the action spectrum causing the lesion seemed to be within the UVB waveband.

A New Approach to the Evaluation of Broad‐spectrum Sunscreens against Ultraviolet and Visible Light‐induced Delayed Tanning

Protection against UV and visible light‐induced delayed tanning (DT) and immediate tanning (IT) of two broad‐spectrum sunscreens with the same sun protection factor was investigated. Protection factors (PFs) against DT (24 h and 7 days) of the sunscreens differed significantly, but PFs against IT did not. This study indicates that using PF against 24 h DT is more appropriate for an evaluation of broad‐spectrum sunscreens against UVA and visible light than IT.