Kazuhiro Miyazaki

Tyrosinase as glycoprotein

SummaryPurified tyrosinase T1 was incubated with neuraminidase. The catalytic activity of tyrosinase was essentially retained, after this treatment. The tyrosinase band (Dopa stained) was transformed into a new less anodic form, similar to tyrosinase T2, on disc electrophoresis. The band of protein was also converted to the same position as the Dopa stained.The other hand, the only one PAS stained band of native tyrosinase T1 was splitted into the three slower-moving bands. One was consistent with Dopa and protein stained bands. The other two were much moro slower than the former band and completely free of peptide and enzymic activity. The PAS-densitometric value of native tyrosinase T1 was almost equal to those of three separated bands in total.These results suggest that mammalian tyrosinase is a kind of glycoprotein.ZusammenfassungBei Inkubation von gereinigter Tyrosinase T1 mit Neuraminidase blieb die katalytische Aktivität von Tyrosinase im wesentlichen erhalten. In der Disc-Elektrophorese erschien das Tyrosinaseband (bei Dopa-Färbung) als neue, weniger anodische Form, ähnlich der Tyrosinase T2.Andererseits erschien das einzige PAS-gefärbte Band der nativen Tyrosinase T1 in Form von drei langsam wandernden Bändern. Eines davon entsprach Dopa und proteinhaltigen Bändern. Die beiden anderen wanderten wesentlich langsamer und waren frei von Peptiden und enzymatischer Aktivität. Die PAS-Dichtemeßwerte der nativen Tyrosinase T1 waren fast so groß wie die zusammengenommenen Werte der einzelnen Banden.Die Ergebnisse lassen vermuten, daß die Säugetier-Tyrosinase eine Art Glykoprotein darstellt.

Tiopronin‐induced Lichenoid Eruption in a Patient with Liver Disease and Positive Patch Test Reaction to Drugs with Sulfhydryl Group

A 62‐year‐old woman suffering from liver cirrhosis developed lichenoid eruptions after 2 years of treatment with tiopronin. The lesions healed spontaneously within a month after withdrawal of the drug. In patch testing, the patient reacted positively, not only to tiopronin, but also to captopril and D‐penicillamine, neither of which she had ever taken before. The provocation test was positive only to tiopronin, and its histological findings revealed lichenoid reaction. It is suggested that the sulfhydryl group may play a role in the etiology of tiopronin‐induced lichenoid drug eruption.

Beneficial clinical effects of cyclosporin A on severe psoriasis and its dissociation from serum concentration of soluble interleukin-2 receptor, soluble interleukin-6 receptor, soluble CD14 antigen, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1

Psoriasis is a disease characterized by hyperproliferation of epidermal keratinocytes and infiltrates of mononuclear cells in the dermal epidermal junction. Several studies have suggested autoimmune mechanisms in the pathogenesis of psoriasis, and this view is confirmed by the fact that immunosuppressive therapies are beneficial in psoriasis. Activated T lymphocytes and keratinocytes produce several cytokines such as interleukin-1 (IL-1), IL-6, or tumor necrosis factor-α (TNF-α), which have been found to be elevated in the serum of psoriatic patients [1]. In psoriasis, trafficking of T cells into the skin is one of the main pathological events and precedes histological changes in epidermal cells [2]. The augmented expression of cell adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1), has been reported in psoriatic lesions [1]. Soluble IL-2 receptor (sIL-2R) is shed from the cell membrane during T-cell activation [3]. CD14 is a newly discovered cell surface marker on monocytes that is shed after cell activation [4]. In inflamed skin, the expression of ICAM-1 on keratinocytes or peripheral blood monocytes has been found, and this adhesion molecule is also released [5, 6]. Soluble ICAM-1 (sICAM-1) plays a role in mediating cell to cell adhesion during inflammatory responses. Raised sIL-2R, soluble CD14 (sCD14), and sICAM-1 levels have been found in psoriatic patients [7–9]. In this study, the concentrations of soluble forms of several cytokine receptors and adhesion molecules were measured using an enzymelinked immunosorbent assay (ELISA) technique before cyclosporin A (CsA) therapy and after remission, and the association of the extent of psoriasis, as assessed by the psoriasis area and severity index (PASI), with the levels of these cytokines and adhesion molecules was also examined. A group of 16 patients with severe psoriasis vulgaris (all men, aged 26–71 years) were enrolled in this study. Psoriasis was clinically assessed using the PASI score. The PASI scores ranged from 13.2 to 53.8 (median 25.7). Before starting oral CsA (Sandimmune; Sandoz) therapy the patients provided consent, and they had not been treated with systemic prednisolone, retinoid or methotrexate. CsA was started at a dose of 2 mg/kg per day and gradually increased to 5 mg/kg per day until remission was induced, and then the CsA was gradually tapered. Blood samples were collected from the 16 patients before starting CsA and after remission, and the serum was stored at –20°C until use. The concentrations of sIL-2R (Cellfree IL-2R, Yamanouchi, Tokyo, Japan; normal 246–702 U/ml), sIL-6R (Biotrack IL-6SR, Amersham, UK; normal 12.5– 40.5 ng/ml), sICAM-1 (ICAM-1 ELISA kit, Bender Medical Systems, Vienna; normal 82.5–276 ng/ml), sVCAM-1 Toshiyuki Yamamoto · Kyoko Kimura · Ichiro Katayama · Taeko Koyano · Akira Mamada · Kazuhiro Miyazaki · Toshikatsu Irimajiri · Yoshiro Furuse · Kiyoshi Nishioka