PADMA 28, a multi-component herbal mixture formulated according to an ancient Tibetan recipe, was assessed for effects on human dermal fibroblasts and epidermal keratinocytes in monolayer culture, and for effects on human skin in organ culture. PADMA 28 stimulated survival of fibroblasts in monolayer culture. In fibroblast monolayer culture and human skin organ culture, levels of matrix metalloproteinase-1 (MMP-1; interstitial collagenase) were reduced and type I procollagen production was increased. When keratinocytes were examined, there was no evidence of growth stimulation over a wide range of PADMA 28 concentrations. At high concentration, PADMA 28 inhibited keratinocyte proliferation. When organ cultures of human skin were treated with PADMA 28, there was no evidence of hyperplastic growth in the epidermis. Topical treatment of rhino mice with PADMA 28 failed to induce epidermal hyperplasia and was completely non-irritating. The ability to stimulate collagen production and inhibit the major collagen-degrading enzyme in skin without inducing a hyperplastic response in the epidermis may provide a basis for development of the herbal preparation as a "skin-repair" agent.

Phototoxicity of visible light laser on the porphyrin-producing bacteria, Porphyromonas gingivalis, in the absence of photosensitizers and under aerobic conditions was shown in previous studies. Recently, we found that the noncoherent visible light sources at wavelengths of 400-500 nm, commonly used in restorative dentistry, induced a phototoxic effect on P. gingivalis, as well as on Fusobacterium nucleatum, and to a lesser extent on the Streptococci sp. To elucidate the mechanism of this phototoxic effect, P. gingivalis and F. nucleatum were exposed to light (1) under aerobic and anaerobic environments and (2) in the presence of scavengers of reactive oxygen species (ROS). Phototoxic effect was not observed when the bacteria were exposed to light under anaerobic conditions. Dimethyl thiourea, a hydroxyl radical scavenger, was effective in reducing phototoxicity (P