The combination of light and chemicals to treat tumors and inflammatory diseases is widely practiced in clinical medicine, and is contributing to the photodynamic therapy (PDT) of various diseases in dermatological fields. In PDT for skin cancers, 5-aminolevulinic acid (5-ALA) is applied topically to the affected area to be absorbed percutaneously through passive diffusion. It typically requires 4 — 6 h for the photosensitizer to penetrate the epidermis deep enough for PDT. In this study, we attempted to shorten the penetration time by using monophasic pulse iontophoresis in Bowen's disease patients. In all subjects, the production of protoporphyrin IX was confirmed after iontophoretic application of 5-ALA as reaching the levels comparable to those reached by the conventional occlusive dressing technique. The effect of ALA-PDT on the patients' skin was assessed by colorimetric imaging. Skin biopsies showed disappearance of tumor cells from the treated lesion.
To obtain insights into the roles of microtubules in cell motility and chemotaxis, we have treated randomly migrating or chemotactically responding Dictyostelium cells with nocodazole, a microtubule-disrupting reagent, and analyzed their motility and shape changes from time-lapse phase-contrast microscope images. Nocodazole treatments at 50 μM for 30 minutes, which sufficiently disrupted dynamic microtubules, made the speed of cell migration significantly faster (120%) as well as induced more frequent cell shape changes. That is, the cells became less polarized and generated pseudopods more frequently. Therefore, microtubules might be a negative regulator of pseudopod formation, and may thus play a role in establishing and/or maintaining the cell polarity by suppressing multiple pseudopod generation. With regard to chemotaxis, the nocodazole treated cells showed normal chemotactic migration, and their additional pseudopod formation was suppressed normally compared to control cells in a steep gradient of chemoattractant cAMP. Thus, strong chemoattractant signals seems to be able to compensate for the lack of dynamic microtubules. The nocodazole treatment did not affect the multicellular morphogenesis during the development of the cellular slime mold. On the other hand, in a shallower gradient, the cells showed slight but significant decreases in chemotactic efficiency. Although microtubules are dispensable in steep gradients of cAMP, they may play a role in increasing the efficiency of chemotaxis in shallow gradients.
Protease-activated receptors (PARs) mediate cellular responses to various proteases in numerous cell types, including nerve cells. The issue of whether stimulation of PARs induces responses in neurons and satellite cells of sympathetic superior cervical ganglia (SCG) of rats was examined with special reference to PAR mRNA levels and to intracellular Ca2+ ([Ca2+]i) changes, since [Ca2+]i is a key factor in intracellular signaling. SCG whose essential structural integrity was maintained intact were used. RT-PCR showed that SCG expressed mRNAs encoding PAR1, 2 and 3, and PAR2 expression was the highest. Confocal microscopic analysis indicated that thrombin and trypsin induced an increase in [Ca2+]i in some neurons and many satellite cells. These proteases initially elicited a [Ca2+]i increase in satellite cells and a subsequent [Ca2+]i change in neurons. Synchronized [Ca2+]i changes in satellite cells were often observed. Neither the removal of extracellular Ca2+ nor Ca2+ channel blockers affected the trypsin-induced or PAR2-activating peptide (PAR2-AP)-induced [Ca2+]i changes in satellite cells, thus suggesting that these changes were caused by Ca2+ mobilization from an internal store, but not by Ca2+ influx. However, neither the phospholipase C inhibitor, U73122, nor the IP3 receptor antagonist, heparin, could inhibit the [Ca2+]i changes of satellite cells, whereas these reagents considerably inhibited the [Ca2+]i changes of neurons. These findings demonstrate the presence of PARs in sympathetic nervous tissue, and establish that proteases induce [Ca2+]i changes in both neurons and satellite cells via Ca2+ mobilization.