Pharmacological modulation of reactive oxygen species (ROS) improves the airway hyperresponsiveness by shifting the Th1 response in allergic inflammation induced by ovalbumin.

Asthma is an allergic inflammation driven by the Th2 immune response with release of cytokines such as IL-4 and IL-13, which contribute to the airflow limitations and airway hyperresponsiveness (AHR). The involvement of oxidative stress in this process is well-established, but the specific role of the superoxide anion and nitric oxide in asthma are poorly understood. Thus, the aim of this study was to investigate the mechanisms underlying the superoxide anion/nitric oxide production and detoxification in a murine asthma model. BALB/c male mice were sensitised and challenged with ovalbumin (OVA). Pretreatments with either apocynin (14 mg/kg) or allopurinol (25 mg/kg) (superoxide anion synthesis inhibitors), aminoguanidine (50 mg/kg) (nitric oxide synthesis inhibitor) or diethyldithiocarbamate (100 mg/kg) (superoxide dismutase inhibitor) were performed 1 h before the challenge. Our data showed that apocynin and allopurinol ameliorated AHR and reduced eosinophil peroxidase, as well as IL-4 and IL-13 levels. Apocynin also abrogated leukocyte peribronchiolar infiltrate and increased IL-1ß secretion. Aminoguanidine preserved lung function and shifted the Th2 to the Th1 response with a reduction of IL-4 and IL-13 and increase in IL-1ß production. Diethyldithiocarbamate prevented neither allergen-induced AHR nor eosinophil peroxidase (EPO) generation. All treatments protected against oxidative damage observed by a reduction in TBARS levels. Taken together, these results suggest that AHR in an asthma model can be avoided by the down-regulation of superoxide anion and nitric oxide synthesis in a mechanism that is independent of a redox response. This down-regulation is also associated with a transition in the typical immunological Th2 response toward the Th1 profile.

Sperm and Egg Jelly Coat from Sea Urchin Lytechinus variegatus Collected in Rio de Janeiro Contain Distinct Sialic Acid-Rich Polysaccharides

This work found the occurrence of a distinct sialic acid-rich polysaccharide in the sperm surface of the sea urchin Lytechinus variegatus, which differed significantly from a similar molecule found in the egg jelly. The sperm polysaccharide extracted by protease digestion was purified using anion exchange chromatography and characterized using agarose gel electrophoresis, gas chromatography/mass spectrometry and NMR spectroscopy. This polysaccharide was highly sulfated and composed almost exclusively of N-acetylneuraminic acid. In contrast, the sialic acid-rich polysaccharide from the egg jelly was composed of N-glycolylneuraminic acid and contains several other hexoses in its structure. This new molecule could help to characterize in further detail the mechanism of fertilization in the sea urchin model system. Sulfated polysaccharides from the jelly coat of sea urchins showed species-specificity in inducing the sperm acrosome reaction, providing an example of a signal transduction event regulated by the sulfated polysaccharide. The new sialic acid-rich polysaccharide found in the sperm head could represent a new molecule involved in the biology of the sea urchin fertilization.

Hepatic alterations in giant bullfrog induced by tordon 2,4-D

Liver fragments of Rana catesbiana, experimentally exposed to 2,4 dichlophenolacetic (tordon 2,4-D) were processed for routine tranmission electron microscopy. Hepatic peroxisomes were visualized after incubation with alkaline 3,3'-diaminobenzidine (DAB) according to the method described by LEHIR et al (1979). Ultrastructural analysis revealed progressive hepatocyte changes induced by this drug. After 2-weeks, the hepatocytes presented evident dilatation and disorder of usual morphology of both smooth abd rough endoplasmic reticulum (SER and RER, respectively). Reduction of glycogen granules associated with an increased frequency of lysosomes was observed. Peroxisomes appeared in clusters with usual morphology. The RER displayed usual appearance but were more often observed in stacks. Lipid droplets were also visualized. After 4-weeks, there was a new increase of glycogen associated with a great number of mitochondia and peroxisomes. Moreover, SER and RER were still dilated. Intracellular lipid inclusions became more abundant. The present study demonstrates that the tordon 2,4-D induces untrastructural changes in the hepatocyte of Rana catesbiana.