In-vivo data on the influence of tobacco smoke and UV light on murine skin.

Inhaled tobacco smoke comes in direct contact with few organs such as mouth, lungs, and stomach. Cigarette smoke (CS) in lungs has been extensively studied. However, limited data exist on its effect on skin, and there are no long-term experimental studies suggesting toxic effects on skin. Even though it is generally accepted that CS is among the main factors of skin aging, the number of experimental studies showing this aging effect is limited. We hereby studied the effect of long-term exposure to CS on the skin of hairless mice in combination with or without ultraviolet (UV) light. In addition, we investigated potential skin protection by a potent antioxidant namely procyanidine-rich French maritime pine bark extract (PBE) pycnogenol. Male and female hairless SKH-2 mice were exposed for 10 months to tobacco smoke and/or UV light in vivo, and their effects on skin were investigated. Some biophysical parameters such as development of erythema, transepidermal water loss (TEWL), and skin elasticity were measured. The results show that UV and CS may be acting synergistically, as shown by the enhanced TEWL, erythema values, epitheliomas, and squamous cell carcinomas (SCCs) observed, whereas PBE seems to protect skin against SCC.

Accumulation of vinblastine into transfersomes and liposomes in response to a transmembrane ammonium sulfate gradient and their cytotoxic/cytostatic activity in vitro.

Vinblastine was encapsulated into liposomes composed from lipids dimiristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC), with cholesterol and transfersomes with sodium cholate prepared by the thin film hydration method. The percentage of vinblastine encapsulation, the stability of transfersomes and liposomes and the rate of release of encapsulated vinblastine at 37 degrees C were studied. The results showed that encapsulation of vinblastine into liposomes was higher than 98% at a drug/phospholipid molar ratio from 0.17 to 0.18, while encapsulation of vinblastine into transfersomes varied from 50% to 80% at a drug/phospholipid molar ratio from 0.05 to 0.09. The retention of drug in liposomes and in transfersomes was found to be time/dependent. The retention of drug in transfersomes compared to the liposomes was reduced due to the presence of sodium cholate which caused destabilization and reduced the main phase transition temperature Tm of the PC bilayers. The cytotoxic/cytostatic activity of the two liposome formulations and the two transfersome formulations with or without encapsulated vinblastine were examined against nine human cell lines and the parameters GI50, TGI, LC50 were estimated according to the NCI protocol. Free DPPC/sodium cholate liposomes found to exhibit strong antiproliferative activity in contrast to the other three free liposomal formulations (DPPC/cholesterol, DMPC/cholesterol, DMPC/sodium cholate). On the other hand, vinblastine encapsulated into the liposomes found to exhibit 20-fold less activity on average, in the three parameters calculate compare to the free vinblastine.

Encapsulation of vinblastine into new liposome formulations prepared from triticum (wheat germ) lipids and its activity against human leukemic cell lines.

Liposomes prepared from lipids isolated from Triticum sp. (wheat germ) were used to investigate the percentage of Vinblastine encapsulation and its retention into liposomes. The wheat germ total lipids (TL) were extracted by the Bligh-Dyer method and the lipid classes have been isolated using chromatographic techniques. The type of lipids and their percentage content have been examined by TLC coupled with an FID (latroscan). Two liposomal formulations, i.e., I and II, with encapsulated vinblastine, and formulation III (empty liposomes) have been prepared by thin film hydration method. The cytotoxic/cytostatic activity of these liposomal formulations have been examined against nine human leukemic cell lines. The results showed that the percentage content of vinblastine into liposomes I and II depended on the lipid composition and it was greater into formulation II (> 90%). The retention of the drug into liposomes was studied and found to be time-dependent at 37 degrees C. For the cytotoxic/cytostatic activity, the parameters GI50, TGI, LC50 were estimated according to the instructions given by the NCI. The results show that formulation III (empty liposomes), exhibited a growth inhibiting activity, against the most tested cell lines. Formulation II showed mean of LC50 at 124.6 nM, mean of TGI at 71.6 nM and mean of GI50 at 30.8 nM.

Chemical analysis and antimicrobial activity of the resin Ladano, of its essential oil and of the isolated compounds.

Fractionation of the resin Ladano from Cistus creticus subsp. creticus and susceptibility testing using the chromatographic fractions showed that its antistaphylococcal activity was mainly due to the diterpene sclareol. The antimicrobial activity of its essential oil, of the chromatographic fractions, and of the isolated compounds was also evaluated against Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus hominis.

Penetration and distribution of alpha-tocopherol, alpha- or gamma-tocotrienols applied individually onto murine skin.

To evaluate skin penetration of various vitamin E homologs, a 5% solution of either alpha-tocopherol, alpha-tocotrienol, or gamma-tocotrienol in polyethylene glycol was topically applied to SKH-1 hairless mice. After 0.5, 1, 2, or 4 h (n = four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5-micron sections--SC1 and SC2), epidermis (next two 10-micron sections--E1 and E2), papillary dermis (next 100 microns, PD), dermis (next 400 microns, D), and subcutaneous fat (next 100 microns, SF). SC1 contained the highest vitamin E concentrations per mu thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers--the lowest layers, PD (40 +/- 15%) and D (36 +/- 15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands--lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.

Efficacy of topically applied tocopherols and tocotrienols in protection of murine skin from oxidative damage induced by UV-irradiation.

To assess the efficacy of various forms of vitamin E in protection of skin from UV-light-induced oxidative stress, vitamin E (tocotrienol-rich fraction of palm oil, TRF) was applied to mouse skin and the contents of antioxidants before and after exposure to UV-light were measured. Four polypropylene plastic rings (1 cm2) were glued onto the animals' backs, and 20 microliters 5% TRF in polyethylene glycol-400 (PEG) was applied to the skin circumscribed by two rings and 20 microliters PEG to the other two rings. After 2 h, the skin was washed and half of the sites were exposed to UV-irradiation (2.8 mW/cm2 for 29 mi: 3 MED). TRF treatment (n = 19 mice) increased mouse skin alpha-tocopherol 28 +/- 16-fold, alpha-tocotrienol 80 +/- 50-fold, gamma-tocopherol 130 +/- 108-fold, and gamma-tocotrienol 51 +/- 36-fold. A significantly higher percentage of alpha-tocopherol was present in the skin as compared with that in the applied TRF. After UV-irradiation, all vitamin E forms decreased significantly (p < .01), while a larger proportion of the vitamin E remained in PEG-treated (approximately 80%) compared with TRF-treated (approximately 40%) skin. Nonetheless, vitamin E concentrations in irradiated TRF-treated skin were significantly higher than in the nonirradiated PEG-treated (control) skin (p < .01). Thus, UV-irradiation of skin destroys its antioxidants: however, prior application of TRF to mouse skin results in preservation of vitamin E.

Kinetic study of cutaneous and subcutaneous distribution following topical application of [7,8-14C]rac-alpha-lipoic acid onto hairless mice.

To diminish oxidative injury, topically applied antioxidants must reach susceptible cells. alpha-Lipoic acid is a potent thiol antioxidant that might be useful for skin protection; therefore, its skin penetration kinetics were assessed. The cutaneous and subcutaneous distributions of [7,8-14C]rac-alpha-lipoic acid were studied in anesthetized hairless mice after application of a 5% solution in propylene glycol for 0.5 to 4 hr. The mice were killed; then the skin was washed, and the stratum corneum was removed by 10 cellophane tape strippings. A punch biopsy of the frozen, stripped skin was sectioned, and amounts of [14C]-alpha-lipoic acid were determined in strippings and slices of epidermis (4 x 5 microns), dermis, and subcutaneous fat (10 x 10 microns, 20 x 20 microns). The rate of [14C]-alpha-lipoic acid absorption into skin was constant by 30 min (0.10 +/- 0.01 nmol/cm2/min); maximum skin concentrations were reached by 2 hr. The [14C]-alpha-lipoic acid penetration kinetics into the first layer of the stratum corneum predicted its penetration through the stratum corneum and subsequent percutaneous absorption (r2 = 0.96, P < 0.02). Cutaneous absorption of unlabeled alpha-lipoic acid and its reduction to the more potent antioxidant form, dihydrolipoic acid, were also demonstrated, using HPLC analysis with electrochemical detection. In conclusion, alpha-lipoic acid topically applied to skin penetrated readily, and was reduced to dihydrolipoic acid. Thus, alpha-lipoic acid could potentiate skin antioxidant protection.

Studies in vivo by electron spin resonance of free radical mechanisms implicated in UV-induced skin photocarcinogenesis.

Synopsis Solar ultraviolet radiation (UVR) is implicated in many types of skin damage, such as photodermatoses, photoageing, erythema, pigmentation, skin cancer etc. Free radicals and reactive oxygen species are considered to play an important role in cutaneous photocarcinogenesis. But skin is endowed with photoprotective agents, namely melanins and antioxidant enzymatic and non-enzymatic mechanisms. In this study we describe the in vivo electron spin resonance (ESR) signals of melanins after UVR exposure, using skin specimens of various types of mice, which were taken from different parts of their bodies. The ESR signals were used as a model for testing the antioxidant properties of butylated hydroxyanisole, tocopherol acetate, and octyl p-methoxycinnamate with butyl methoxy dibenzoyl methane and superoxide dismutase (SOD). Additional UVB radiation was applied to the skin samples in situ (in the cavity of the ESR spectrometer). Suppression of ESR signals of melanins was observed in all cases. Etudes in vivo par resonance paramagnetique electronique, après exposition au rayonnement UV, des méchanismes radicalans impliqués a la photocarcinogénèse cutanée.