P de Brito | PubMed Health

PubMed2006

[Pericochlear hypodensity on CT: normal variant in childhood].

PURPOSE: Evaluation of the prevalence of a pericochlear hypodensity on CT in children. Materials and methods. This study correlates the findings on temporal bone CT to the indications for CT (headache, trauma). Helical CT acquisitions using 0,5 mm, 0,6 mm or 0,75 mm slice thickness according to the material available, with multiplanar reconstructions. Only patients with significant pericochlear hypodensity, larger or equal to 0,4 mm, were taken into account, and the curvilinear or nodular nature of the lesion on axial and coronal sections was recorded. RESULTS: A pericochlear hypodensity was identified in nearly 40% of cases. There was no population predominence according to the indication for the CT. The curvilinear type was more frequent on coronal images, with unilateral and bilateral involvement being equally frequent. There was no significant difference according to the sex. Patients of all ages showed lesions, from newborns to adolescents, with increased frequency in childhood. CONCLUSION: This study confirms a high prevalence of pericochlear hypodensity in a paediatric population, without clinical correlation, which requires prudence when interpreting the significance of this CT sign commonly described in association with pericochlear otosclerosis and the pericochlear form of osteogenesis imperfecta.

Adolescent↗

PubMed1985

Role of granulocyte oxygen products in damage of Schistosoma mansoni eggs in vitro.

The objectives of this study were to describe the ultrastructure of granulocyte-Schistosoma mansoni egg interaction and to determine the role of reduced oxygen products as effectors of cell-mediated damage to the parasite target. Granulocytes attached to the parasites and closely applied their plasma membranes to the microspicules of the egg shell 30 min after mixing in the presence of immune serum. By 4 h, the egg shell was fractured and granulocyte pseudopodia extended toward the underlying miracidium. Granulocyte attachment to eggs resulted in release of O2- (0.30-0.52 nmol/min per 2 X 10(6) cells) and accumulation of H2O2 (0.14-0.15 nmol/min) in the presence of antibody or complement. Granulocytes reduced egg tricarboxylic-acid cycle activity and hatching by 28.3 +/- 0.9 and 35.2 +/- 2.8%, respectively (cell-egg ratio of 1,000: 1). Exogenous superoxide dismutase (10 micrograms/ml) inhibited granulocyte toxicity for egg metabolic activity (3.0 +/- 2.1% reduction in acetate metabolism vs. 28.3 +/- 0.9% decrease in controls without superoxide dismutase, P less than 0.0005) and hatching (12.5 +/- 1.8% reduction, P less than 0.0005), whereas catalase and heparin had no effect. Inhibitors of myeloperoxidase (1 mM azide, cyanide, and methimazole) augmented granulocyte-mediated toxicity of egg tricarboxylic-acid cycle activity (44-58% reduction in activity vs. 31 and 35% reduction in controls), suggesting that H2O2 released from cells was degraded before reaching the target miracidium. Oxidants generated by acetaldehyde (2 mM)-xanthine oxidase (10 mU/ml) also decreased egg metabolic activity and hatching by 62.0 +/- 9.0 and 38.7 +/- 7.3%, respectively. Egg damage by the cell-free system was partially prevented by superoxide dismutase (26.5 +/- 4.2% reduction in egg tricarboxylic-acid activity) and completely blocked by catalase (0% reduction in activity). These data suggest that granulocyte-mediated toxicity for S. mansoni eggs is dependent on release of O2- or related molecules. These oxygen products, unlike H2O2, may readily reach the target miracidium where they may be converted to H2O2 or other microbicidal effector molecules.

Acetaldehyde↗