Nevus of Ota: a new classification based on the response to laser treatment.

BACKGROUND AND OBJECTIVE: For 60 years, Tanino's classification has been used to classify the extent of nevus of Ota. However, such classification not only fails to address variants such as phacomatosis pigmentovascularis but also cannot be used to predict the therapeutic outcome. Our objective is to retrospectively study our series of laser-treated patients with the aim of re-classifying nevus of Ota, so that such important issues can be taken into account. STUDY DESIGN/MATERIALS AND METHODS: One hundred nineteen patients that had received Q-switched laser treatment were recruited into the study. They were recalled for interview and examination for evidence of coexisting birthmarks and extracutaneous involvement. Two observers assessed the pre- and posttreatment clinical photographs for evidence of periorbital under-response (panda's sign), defined as the degree of periorbital laser clearing significantly less than clearing in the other area. RESULTS: A total of 47.8% of the patients with periorbital pigmentation were considered by the observers to have significant periorbital under-response (panda's sign). Additionally, 10.1% had other birthmarks, and extracutaneous involvement was seen in 31.4% of the patients. CONCLUSION: Periorbital under-response is commonly seen in patients with periorbital pigmentation. Taking this and other factors into consideration, we have proposed a new classification for nevus of Ota that allows for the prediction of the clinical outcome of laser treatment.

A differential role of extracellular signal-regulated kinase in stimulated PC12 pheochromocytoma cell movement.

Rat pheochromocytoma PC12 cells have been widely used as a cell system for study of growth factor-stimulated cell functions. We report here that nerve growth factor (NGF) stimulated both chemotaxis (directional migration) and chemokinesis (random migration) of PC12 cells. Treatment with a MEK1/2-specific inhibitor (PD98059) or expression of a dominant negative variant of Ras differentially inhibited NGF-stimulated chemotaxis but not chemokinesis of PC12 cells. Priming of PC12 cells with NGF resulted in reduced extracellular signal-regulated kinase (ERK) activation and loss of chemotactic, but not chemokinetic, response. In addition, NGF stimulation of ERK is known to involve an early transient phase of activation followed by a late sustained phase of activation; in contrast, epidermal growth factor (EGF) elicits only early transient ERK activation. We observed that like NGF, EGF also stimulated both chemotaxis and chemokinesis, and treatment with PD98059 abolished the EGF-stimulated chemotaxis. Therefore, the early transient phase of ERK activation functioned in signaling chemotaxis; the late sustained phase of ERK activation did not seem to have an essential role. In addition, our results suggested that chemotactic signaling required a threshold level of ERK activation; at below threshold level of ERK activation, chemotaxis would not occur.