Retinoids are a group of substances comprising vitamin A and its natural and synthetic derivatives. Retinoids were first used in dermatology in 1943 by Straumfjord for acne vulgaris. Since that time, retinoids have been utilized in the management and treatment of various skin conditions, including photoaging. Photodamage of the skin occurs as a consequence of cumulative exposure to solar ultrav...

Studies were carried out on the photodynamic inactivation of Bacillus subtilis cells by He-Ne laser irradiation in presence of methylene blue and toluidine blue. Electron paramagnetic resonance (EPR) measurements show decrease in the cell membrane nuidity due to photodynamic damage of the lipophilic compartments. Study of cell damage in presence of sodium azide, 0 20 and glutathione as well as ...

While chloroaluminum phthalocyanine is a highly effective photosensitizer of murine leukemia P388 or L1210 cells, the mode of cell death varies as a function of the PDT dose. When cells were incubated with 0.3 microM of the sensitizer, a light dose of 45 mJ cm-2 (670 +/- 5 nm) yielded a 90% apoptotic cell population within 60 min. The sensitizer localized throughout the cytoplasm and catalyzed ...

BACKGROUND The periorbital region serves as a barometer of chronologic and environmental age and, as such, patients often seek its cosmetic rejuvenation. OBJECTIVE The purpose of this article was to review the dermatologic treatments available for periorbital skin rejuvenation. METHODS Topical retinoic and glycolic acid preparations, chemical peels, botulinum and collagen injections, dermab...

We employed deep UV (DUV) Raman spectroscopy for characterization of molecular photodamage in cells. 244 nm light excitation Raman spectra were measured for HeLa cells exposed to the excitation light for different durations. In the spectra obtained with the shortest exposure duration (0.25 sec at 16 µW/µm(2) irradiation), characteristic resonant Raman bands of adenine and guanine at 1483 cm(-1)...

Optical trapping is a powerful tool for the micromanipulation of living cells--especially bacteria--but photodamage induced by the laser beam can adversely affect viability. We have explored optical trapping conditions in the near infrared (840-930 nm) that preserve the viability of E. coli, as measured by gene expression of green fluorescent protein. We have found that time-sharing the optical...

During gene transcription, RNA polymerase (Pol) II encounters obstacles, including lesions in the DNA template. Here, we review a recent structure-function analysis of Pol II transcribing DNA with a bulky photo-lesion in the template strand. The study provided the molecular basis for recognition of a damaged DNA by Pol II, which is the first step in transcription-coupled DNA repair (TCR). The r...

Damage caused by excessive, long-term sun exposure contributes to signs of ageing and is most readily recognizable on our external surface, the skin. The damaging effects of the sun are mainly caused by ultraviolet radiation (UVR) which, on earth, consists of UVA (320 to 400 nm) and UVB (280 to 320 nm). The third type of UV radiation, UVC, also called short‐ wave or ionizing radiation, is absor...

Globally, C4 plants dominate hot, open environments, but this general pattern is underpinned by important differences in the biogeography of C4 lineages. In particular, the species richness of C4 Poaceae (grasses) increases strongly with increasing temperature, whereas that of the major C4 eudicot group Chenopodiaceae correlates positively with aridity. Freezing tolerance is a crucial determina...

Endogenous chromophores in human skin serve as photosensitizers involved in skin photocarcinogenesis and photoaging. Absorption of solar photons, particularly in the UVA region, induces the formation of photoexcited states of skin photosensitizers with subsequent generation of reactive oxygen species (ROS), organic free radicals and other toxic photoproducts that mediate skin photooxidative str...