Cellular changes, molecular pathways and the immune system following photodynamic treatment.

Photodynamic therapy (PDT) is a novel medical technique involving three key components: light, a photosensitizer molecule and molecular oxygen, which are essential to achieve the therapeutic effect. There has been great interest in the use of PDT in the treatment of many cancers and skin disorders. Upon irradiation with light of a specific wavelength, the photosensitizer undergoes several reactions resulting in the production of reactive oxygen species (ROS). ROS may react with different biomolecules, causing defects in many cellular structures and biochemical pathways. PDT-mediated tumor destruction in vivo involves cellular mechanisms with photodamage of mitochondria, lysosomes, nuclei, and cell membranes that activate apoptotic, necrotic and autophagic signals, leading to cell death. PDT is capable of changing the tumor microenvironment, thereby diminishing the supply of oxygen, which explains the antiangiogenic effect of PDT. Finally, inflammatory and immune responses play a crucial role in the long-lasting consequences of PDT treatment. This review is focused on the biochemical effects exerted by photodynamic treatment on cell death signaling pathways, destruction of the vasculature, and the activation of the immune system.

Novel, low-cost, highly soluble n-type semiconductors: tetraazaanthracene tetraesters.

New tetraester derivatives of 1,4,5,8-tetraazaanthracene have been prepared and characterized by spectroscopic and electrochemical techniques. The LUMO level of the compounds is close to -4 eV (the so-called air operating stability border in n-channel field effect transistors). Tetraesters were obtained with reasonable yields without the necessity of using high-quality reactants or solvents, resulting in their low cost.

[Practical aspects of drug resistance in schizophrenia]. / Praktyczne aspekty problemu lekoopornosci w schizofrenii.

About 30-60% of patients with schizophrenia show resistance to neuroleptic treatment. In about 5-20% of them the resistance to antipsychotic treatment appears during the first therapy (primary resistance), however in the rest of patients, treatment resistance develops during 5 to 10 years of the illness (secondary resistance). In addition, another group of 5 to 20% of schizophrenics shows intolerance of therapeutic dosages of neuroleptic drugs. Before the diagnose of treatment resistance has been made, there is the need to reconfirm the diagnosis of schizophrenia, exclusion of other psychiatric disorders, assessment of patients' compliance, drug dosing, as well as pharmacokinetic and pharmacodynamic factors which have an impact on the therapeutic effect of antipsychotic treatment. Clozapine seems to be a "gold standard" for treatment of drug-resistant schizophrenic patients, however new atypical antipsychotics should be considered as a new therapeutic strategy, even before clozapine. The use of adjunctive treatment with carbamazepine, lithium, valproic acid, benzodiazepines and others, is a reasonable strategy, however dangerous drug interaction has to be taken into account.