Dynamics of oxidative stress and urinary excretion of melatonin and its metabolites during acute ischemic stroke.

Oxidative stress is a leading cause of neuronal damage in ischemic stroke. Melatonin may play a role in the antioxidant response. Melatonin and its metabolites may be involved in the modulation of oxidative stress in human acute stroke.

Influence of animal species on secondary oxidant activation in serum exposed to singlet oxygen.

Singlet oxygen ((1)O(2)) produced during inflammatory reactions and during photodynamic therapy deactivates by producing in tissues secondary reactive oxygen species and peroxides (SOS) as well as other degradation products. We investigated the influence of animal species on SOS production secondary to standardized (1)O(2) production by performing in vitro experiments with rose bengal as the (1)O(2) producer, human serum (HS) as a control, sera derived from various animal species, and dichloro-dihydro-fluorescein as a nonspecific marker that becomes fluorescent when oxidized. The overall SOS production in HS from a presumed healthy cohort of 53 donors (31 males and 22 females) gave a mean "normal" value of 0.

Serum resistance to singlet oxygen in patients with diabetes mellitus in comparison to healthy donors.

Diabetes mellitus causes endothelial injury through oxidative stress involving reactive oxygen species and peroxides as well as inflammation, both of which consume antioxidant defenses. Singlet oxygen ((1)O(2)) is produced by leukocytes during inflammatory and biochemical reactions and deactivated by producing reactive oxygen species and peroxides. To determine whether serum was capable of deactivating (1)O(2), we triggered a photo reaction in sera from 53 healthy donors and 52 diabetic patients.

Biophysical parameters influencing secondary oxidants activation in human serum exposed to singlet oxygen.

Singlet oxygen (¹O₂), produced during photodynamic therapy, deactivates during its interaction with tissues by producing reactive oxygen species (ROS) and peroxides as well as other degradation products. Here we investigated the role of parameters of light delivery, O(2), and temperature on the ROS and peroxides production, secondary to ¹O₂. A series of simple in vitro experiments has been performed with Rose Bengal (RB) as a ¹O₂ producer, human serum (HS) as a target and dichlorofluorescein (DCFH) as a nonspecific marker, becoming fluorescent when oxidized.

In vitro evaluation of Radachlorin sensitizer for photodynamic therapy.

This paper reports the evaluation of a new photosensitizer, Radachlorin in comparison with one of its well known components but used solely, Chlorin e(6). The photodynamic properties and cell uptake and localisation of the two drugs were compared. In vitro studies were conducted on human adenocarcinoma cells (HT29) and lung carcinoma cell line (A549).

Secondary oxidants in human serum exposed to singlet oxygen: the influence of hemolysis.

Singlet oxygen (1O2) is produced by leucocytes during inflammatory reactions, various biochemical reactions and during photoreactions. It deactivates by reacting with a number of targets to produce reactive oxygen species (ROS) and peroxides (that in turn produce ROS). To verify whether serum had the same capability to deactivate secondary oxidants after exposure to 1O2, we provoked a photoreaction using rose bengal added to sera of 53 healthy donors and, after light delivery, reduced 2',7'-dichlorofluorescein (DCFH) was added at the end of irradiation and fluorescence of the oxidized derivative (DCF) was recorded.

Photodynamic treatment of culture medium containing serum induces long-lasting toxicity in vitro.

Photodynamic therapy (PDT) produces singlet oxygen and reactive oxygen species (ROS) that damage tumor cells and the vasculature. The resulting effect is a balance between photo-oxidations through primary or secondary ROS and scavenging activity. Sensitizers are distributed in the extracellular space before and during cell sensitization, suggesting that PDT could act directly on cell structures and on extracellular compartments, including sera.