Joselito Nardy Ribeiro

Involvement of mitochondria in apoptosis of cancer cells induced by photodynamic therapy

A terapia fotodinâmica (TFD) e um promissor tratamento clinico que emprega a combinacao de luz visivel, oxigenio e uma substância fotossensibilizadora para tratar doencas de carater oncologico. Esse tipo de tratamento induz a morte celular programada (apoptose) em tecido tumoral. No entanto, o mecanismo de inducao de apoptose por TFD nao esta bem caracterizado. Muitos fotossensibilizadores possuem como alvo principal a mitocondria. O tratamento com TFD causa danos nessa organela e induz a apoptose atraves da liberacao de citocromo c, fator de inducao de apoptose, Smac/DIABLO e certas pro-caspases. A liberacao dessas proteinas, a partir da mitocondria, e regulada por uma familia de proteinas pro e antiapoptoticas, conhecida como familia BCL-2. A proposta dessa minirrevisao e apresentar algumas publicacoes recentes que focalizam o envolvimento da mitocondria em apoptose de celulas cancerigenas induzida por TFD.A terapia fotodinâmica (TFD) e um promissor tratamento clinico que emprega a combinacao de luz visivel, oxigenio e uma substância fotossensibilizadora para tratar doencas de carater oncologico. Esse tipo de tratamento induz a morte celular programada (apoptose) em tecido tumoral. No entanto, o mecanismo de inducao de apoptose por TFD nao esta bem caracterizado. Muitos fotossensibilizadores possuem como alvo principal a mitocondria. O tratamento com TFD causa danos nessa organela e induz a apoptose atraves da liberacao de citocromo c, fator de inducao de apoptose, Smac/DIABLO e certas pro-caspases. A liberacao dessas proteinas, a partir da mitocondria, e regulada por uma familia de proteinas pro e antiapoptoticas, conhecida como familia BCL-2. A proposta dessa minirrevisao e apresentar algumas publicacoes recentes que focalizam o envolvimento da mitocondria em apoptose de celulas cancerigenas induzida por TFD.

Organoclorados: um problema de saúde pública

The discovery of DDT, the first synthetic organic insecticide, besides giving Paul Mueller, in 1948, the Nobel Prize of Physiology and Medicine, started the age of organochlorine pesticides. After the appearance of DDT, there has been an ever increasing number of pesticides available on the market. Despite the benefits, the indiscriminate use of this substance created serious ecological problems. Currently it is estimated that the percentage of living beings, vegetables and animals, that remain uncontaminated, is relatively low. This article focuses on the serious problem of contamination created by organochlorides, as well as the attemps to solve these problems.

Type II photooxidation mechanism of biomolecules using chloro (5,10,15,20-Tetraphenylporphyrinato) indium (III) as a photosensitizer

The photooxidation mechanism of bovine serum albumin (BSA), L-tryptophan (Trp) and red blood cells (RBC) by chloro(5,10,15,20-tetraphenylporphyrinato)indium(III) (InTPP) was investigated. The photooxidation rate of Trp, BSA and RBC by InTPP was decreased in the presence of NaN3. The presence of D2O increases the photooxidation rate of Trp and BSA and decreases that of RBC. This decrease is probably related to a reduction of the binding constant between InTPP and RBC in the presence of D2O. No significant change in biomolecule fluorescence or in the percent of hemolysis was observed when radical quenchers (ferricyanide, mannitol and dismutase superoxide) were used. Experiments using electron paramagnetic resonance (EPR) show that only 1O2 was generated by InTPP. A mechanistic model based on the preferential oxidation of Trp and BSA by singlet oxygen is proposed. The agreement between the experimental data and the kinetic model gives additional support to the predominance of a mechanism via 1O2 in biomolecule photooxidation by InTPP.