Search

Photodynamic therapy is a relatively new modality of cancer treatment in human and veterinary medicine. It uses a photosensitizing drug called photosensitizer, which in the presence of oxygen delivers reactive species (singlet oxygen and flee radicals) upon irradiation of the tumor with visible light. In contrast to classical chemotherapy, the original compound (sensitizer or photosensitizer) has a minimal toxic effect on the whole body. Its effect is due to the activation of the accumulated sensitizer in a given tissue by visible light around 630 nm wavelength or above. Excitation by light produces activated oxygen- and nitrogen species, which are able to rapidly kill cells. No harming radiation is involved. The administered compound gets activated only in the illuminated area, mainly killing actively dividing cells. The treatment achieves its selectivity by illuminating only the area affected by the tumor. Apparently, it does not solve the problem of metastasis, but offers many advantages against chemotherapy, radiation or surgery. PDT offers an additional method in treat patients with certain kinds of cancer. Here we present some preliminary data on the application of PDT on companion animals with malignant tumors. We have applied 5-aminolevulinic acid (ALA)-based PDT on cats and dogs with different kinds of tumors, and investigated the effect of treatment on reduction-oxidation parameters of tissue samples taken from the tumors before and after PDT. Results of free radical concentrations measured using Electron Spin Resonance and of reduced glutathione in tumor tissues give a direct correlation with the outcome of PDT. [ABSTRACT FROM AUTHOR]

Several micronutrient supplementation strategies are used to cope with oxidative stress, although their benefits have recently been questioned. The aim of the present study was to examine the effects of DL-alpha-lipoic acid (LA) in response to acute exercise and during recovery in horses. Six standardbred trotters were tested on the treadmill before and after 5-week LA supplementation (25 mg/kg body weight/day). According to electron paramagnetic resonance measurements, strenuous aerobic exercise increased significantly free radical formation in the gluteus medius muscle, which was prevented by LA supplementation. The activities of thioredoxin reductase and glutathione reductase in muscle were significantly increased in LA-treated horses, but neither LA nor exercise affected muscle thioredoxin activity. LA increased the concentration of total glutathione in muscle at rest and during recovery. Treatment with LA blunted the exercise-induced increase in plasma oxygen radical absorbance capacity and decreased the post-exercise levels of lipid hydroperoxides in plasma and malondialdehyde in plasma and in muscle. These findings suggest that LA enhances thiol antioxidant defences and decreases exercise-induced oxidative stress in skeletal muscle.

The amphetamine (AMPH)-induced alteration in rat brain dopamine levels modified by N-acetylcysteine (NAC) administration has been examined using isocratic ion-pair reversed-phase high-performance liquid chromatography with electrochemical detection. The aim of the development of a novel validated evaluation scheme implying a double AMPH challenge was to enhance the efficiency of AMPH-triggered dopamine release measurements in rat brain striatal slices by improving the reproducibility of the results. The proposed experimental protocol was tested in vivo and proved to be capable of fast and reliable drug screening for tracing the effect of NAC as a model compound in AMPH-mediated dopaminergic response. The subcellular localization of the dopamine mobilizing effect of NAC has been established indirectly by the use of an irreversible dopamine vesicular depletor, reserpine. The antioxidant NAC at 10 mM plays an important role in the complete suppression of acute AMPH-elicited dopamine release. The possible role of this quenching effect is discussed.

Hungary is among the leading countries in Europe regarding the mortality and incidence of different types of tumours. Therefore, developing effective therapies is especially important in this country. Investigation of tumour formation and progression on the molecular level is required to develop possible therapeutical targets. Such targets can be proteins with tumour suppressor function, which inhibit intracellular signalling processes that under pathophysiological conditions can lead to uncontrolled cell proliferation and tumour formation. Protein e3B1/Abi-1, which belongs to the family of Abl-interactors, was isolated recently as a possible tumour suppressor. As a partner of Abl kinase, its role has been investigated in the development and progression of some types of leukemias, however, more and more experimental data suggest that it is a general suppressor protein. According to the latest results, e3B1/Abi-1 via the Ras small G-protein has an essential role in the regulation of cell proliferation, and via Rac activation it can affect actin remodelling, cell adhesion and migration. Cell proliferation is important in tumour development, while cell adhesion and migration has a role in metastasis formation. The latest results showed deletion of the gene encoding protein e3B1/Abi-1 in prostate cancer, loss of its expression during the progression of some types of leukemias, and there are data on the effect of imatinib mesylate (Gleevec or outside USA Glivec, Novartis), one of the newest drugs in leukemia treatment, on the phosphorylation of e3B1/Abi-1 as well. This report summarizes the data published on protein e3B1/Abi-1, with special interest in practical implications.

Role of R-(-)-deprenyl in adhesion of neuronal and non-neuronal cells. The beneficial effect of the anti-parkinsonian monoamine oxidase-B inhibitor, R-(-)-deprenyl has been shown in a number of different diseases, such as Parkinson's and Alzheimer's disease, atherosclerosis or tumor formation. The role of the cytoskeleton, the main component of cell adhesion, has been suggested in the development of these diseases. Nevertheless, the effect of the drug on cell adhesion has never been examined. In the present study, the authors studied the effect of R-(-)-deprenyl on cell-cell adhesion of neuronal (PC12, rat phaeochromocytoma) and non-neuronal (NIH3T3, NIH3T3/EGFR, NIH3T3/EGFR-e3B1 mouse embryo fibroblasts, and 5180 mouse sarcoma) cells using cell association assay. R-(-)-deprenyl treatment resulted in a cell type- and concentration-dependent increase in cell-cell adhesion of PC12 cells, which contain no monoamine oxidase-B, and we observed the same effect in NIH3T3 cells at concentrations lower than those needed for monoamine oxidase-B inhibition. Interestingly, R-(-)-deprenyl increased cell-cell adhesion of tumor cell lines as well. The effect of R-(-)-deprenyl was not reversible during a 24-hour recovery period. At the same time, the monoamine oxidase-B inactive isomer of the drug, S-(+)-deprenyl had no effect on cell-cell adhesion in PC12 and NIH3T3 cells. In this study, the authors described a new, monoamine oxidase-B independent effect of R-(-)-deprenyl on cell-cell adhesion both in neuronal and non neuronal cells. The authors' results with S-(+)-deprenyl suggest that the sterical structure of the drug is an important factor of the observed effect, which is probably a consequence of an irreversible change in the cells.

Unlabelled: The effect and possible mechanisms of action of aminoguanidine (a preferential iNOS inhibitor) has been studied on cardiovascular damages and overproduction of reactive nitrogen species in streptozotocin-induced diabetic rats., Materials and Methods: 40 rats were divided into five groups (control and diabetic, with or without aminoguanidine treatment, diabetic with insulin treatment) and oxidative stress parameters were examined. Tissue nitric oxide levels were determined by EPR spectroscopy, while peroxynitrite generation by a chemiluminescence method. Cardiac hypertrophy, blood metabolic parameters (blood glucose, HbA1c, fructosamine), as well as tissue protein carbonyl levels were also determined., Results: Diabetic animals showed increased nitric oxide and peroxynitrite generation in the aorta along with a significant hypertrophy and protein carbonylation of the cardiac tissue. Both aminoguanidine and insulin treatment suppressed high levels of nitric oxide and peroxynitrite in the vasculature, but only aminoguanidine was able to prevent hypertrophic alterations and to reduce protein carbonylation in the heart., Conclusions: The results show that (1) aminoguanidine reduces nitric oxide production and prevents cardiac hypertrophy, (2) insulin therapy improves carbohydrate metabolism, reduces nitrosative stress but has no effect on cardiac hypertrophy. Cardiac hypertrophy in diabetes is strongly correlated with non-enzymatic glycation. Aminoguanidine prevented hypertrophy by blocking the formation of advanced glycation end products rather than via other mechanisms.