Clinical aspects of photodynamic therapy--Romanian experience.

Photodynamic therapy is an emerging method for local destruction of tissue by generating toxic oxygen species using light absorbed by an administered or an endogenously generated photosensitiser. It is a promising treatment for patients with cancer. More recently it has found increasing use as a method of therapy for non-cancerous illnesses. Following administration of a photosensitiser occurs an accumulation or retention in areas of cancer and disease relative to adjacent normal tissue. The photosensitiser is inactive until irradiated by light, following which cellular destruction occurs. This explanation is a good reason for the scientific and clinical interest in photodynamic therapy.

Photochemical and photodynamic properties of vitamin B2--riboflavin and liposomes.

Ocular neovascular disease represents an important cause of blindness today. In this paper, it was used a model to evaluate the vaso-occlusive potential of photodynamic therapy with B2 vitamin. Neovascularization induced în an occular cornea consists of an easily accessible monolayer-like neovascular net within a transparent matrix. This fact allows studying the efficiency of occlusion în an isolated neovascular structure. This study is a requirement for the transport evaluation and photodynamic efficiency of this drug. Both riboflavin and the DPBF are embedded în the phospholipid bilayer. The quantum yield of DPBF photooxidation and riboflavin singlet oxygen generation are higher by comparison with water (13-35 s în liposomes and 0.4 s în water), due to the higher lifetime of singlet oxygen în liposomes and due to the special transport mechanism of B2 inside of liposomes. The photochemical behavior of riboflavin (Vitamin B2) aqueous solution and în unilamellar liposomes of dipalmitoyl phosphatidylcholine (DPPC) during the sensitized photooxidation of 1,3-diphenylisobenzofuran (DPBF) are discussed în this paper. Some structural aspects of DPPC liposomes, have been studied, too. The first step în the sequence of vesicle shape transformations, the spherical to polygonal shape transition, occurs în a very narrow temperature range, i.e., during the gel-to-liquid crystalline phase transition. At different temperatures (30,37-42 degrees C) could be seen the sequence for the vesicle form: spherical-polygonal-ellipsoidal, attributable to the lipid domain coexistence on the macroscopic structure of liposomes. The incorporation of B2 Vitamin eliminates the ellipsoidal form of DPPC, even at high temperature, because B2 has a very small molecule able to be encapsulated into DPPC vesicle. Also, the incorporation of B2 increase the DPPC diameter, all these observations being obtained by optical confocal microscopy.

Photodynamic occlusion of ocular neo-vascularization with B2 vitamin.

Photodynamic therapy (PDT) of cancer has been known for over twenty years and is based on the dye-sensitized photooxidation of different biological targets in the tumoral tissue yielding to a photochemically induced cell's death via apoptotic pathways. Several parameters affect clinical trials in PDT and influence the therapeutic outcome. A potentially major application of PDT in a non-cancer field is its use in treatment of age-related macular degeneration. This condition, caused by proliferation of neovasculature in the retina, is the major cause of blindness in the over 50s. Using a photosensitiser which enters neovasculature very rapidly following administration and is subsequently quickly moved from the circulation. Ocular neovascular disease represents an important cause of blindness today. In this paper, was used an animal model (rabbit) to evaluate the vaso-occlusive potential of photodynamic therapy with B2 vitamin. Neovascularization induced in the rabbit cornea consists of an easily accessible monolayer-like neovascular net within a transparent matrix. This fact allows studying the efficiency of occlusion in an isolated neovascular structure.