Identification of two taurine receptor subtypes on the primary afferent terminal of frog spinal cord.

1. Effects of taurine on primary afferent terminals in the frog spinal cord were examined by a sucrose-gap method applied to a dorsal root (9th or 10th segment). 2. In a normal Ringer solution, taurine (1 mM, applied for 5s at a rate of 0.04 ml s-1, 0.2 mumol) caused a hyperpolarization, but a higher concentration (10 mM, applied at the same rate, 2.0 mumol) caused a biphasic response consisting of a hyperpolarization followed by a slow onset depolarization. A similar biphasic response could also be observed in tetrodotoxin-treated preparations. 3. When the concentration of extracellular Mg2+ was increased up to 9.0 mM, the depolarizing response to taurine was augmented. The rate of the augmentation was dependent upon the extracellular Mg2+ concentration. 4. The depolarizing effect was selectively antagonized by bicuculline in concentrations (10-30 microM) that had no significant antagonizing action on gamma-aminobutyric acid (GABA)-induced depolarization. On the other hand the hyperpolarizing effect of taurine was selectively reduced by strychnine (0.1 microM) which had no antagonizing effect on responses to glycine. 5. These results suggest that in the frog spinal cord there are at least two subtypes of taurine receptor whose pharmacological profiles resemble GABA and glycine receptors in the mammalian central nervous system, and whose sensitivity may be modulated by extracellular Mg2+.

Sclerotic fibromas of the skin.

We report a case of a 34-year-old Japanese woman with a fibrous tumor on the left palm that fulfilled the criteria of sclerotic fibroma of the skin. Immunohistochemically, the tumor cells were positive for vimentin, but negative for S-100 protein and neuron-specific enolase. Ultrastructurally, the cross-striations of collagen microfibrils were less prominent. Our case supports the concept that sclerotic fibroma of the skin is a distinctive lesion which may represent a hamartoma of the skin.

A case of contact dermatitis due to methylprednisolone.

A 46-year-old woman developed contact dermatitis on her face after application of an ointment containing 0.1% methylprednisolone and 0.35% fradiomycin. Her patch test result was positive with methylprednisolone, but not with fradiomycin. No cross-reactions were observed after conducting patch tests with 17 different topical corticosteroids including prednisolone.

Eccrine porocarcinoma.

We describe a 78-year-old woman with eccrine porocarcinoma presenting a zosteriform appearance on the lateral upper part of the buttock. Erosion and bleeding were observed in the center of a 50 X 80 mm, erythematous indurated plaque with an elevated border. Posterior to the plaque, there was another erosive plaque, 50 X 20 mm in diameter, with peripheral induration overlaid by two reddish papules. Based on the previous reports of 21 patients with eccrine porocarcinoma in Japan, we discuss the relationship between the clinical pattern and lymph node metastasis. The pedunculated eccrine porocarcinoma has less tendency to metastasize to the regional lymph nodes than the nonpedunculated form.