Andre Amaral | PubMed Health

PubMed2006

Freshwater molluscs from volcanic areas as model organisms to assess adaptation to metal chronic pollution.

Cellular biomarkers of exposure and biological effects were measured in digestive gland of snails (Physa acuta) sampled in sites with and without active volcanism in São Miguel Island (Azores). Metal content in digestive cell lysosomes was determined by image analysis after autometallography (AMG) as volume density of autometallographed black silver deposits (Vv(BSD)). Lysosomal structural changes (lysosomal volume, surface and numerical densities - Vv(LYS,) Sv(LYS) and Nv(LYS-), and surface-to-volume ratio - S/V(LYS)-) were quantified by image analysis, after demonstration of beta-glucuronidase activity, on digestive gland cryotome sections. Additional chemical analyses (atomic absorption spectrophotometry) were done in the digestive gland of snails. The highest metal concentrations were found in snails from the active volcanic site, which agreed with high intralysomal Vv(BSD). Digestive cell lysosomes in snails inhabiting sites with active volcanism resembled a typical stress situation (enlarged and less numerous lysosomes). In conclusion, the biomarkers used in this work can be applied to detect changes in metal bioavailability due to chronic exposure to metals (volcanism), in combination with chemical analyses.

Adaptation, Physiological↗

PubMed2004

Use of low tidal volume in septic shock may decrease severity of subsequent acute lung injury.

Recent studies have indicated that protective lung strategies may improve outcomes in acute lung injury. We hypothesized that the use of a lower tidal volume early during septic shock may protect against the subsequent development of acute lung injury. Fourteen fasted, anesthetized, invasively monitored, mechanically ventilated, female sheep (26.4 +/- 4.5 kg) underwent cecal ligation and perforation to induce sepsis. Sheep were then randomized to ventilation with low (6 mL/kg) or high (12 mL/kg) tidal volumes. A positive end-expiratory pressure of 10 cm H(2)O was applied in each case. Ringer's lactate was titrated to maintain pulmonary artery occlusion pressure at baseline levels. No vasoactive agents or antibiotics were used. Survival time was longer in the low- than in the high-tidal-volume group (21.8 +/- 2.4 vs. 17.6 +/- 4.1 h, respectively, P < 0.05). The times to develop hypotension and anuria were longer in the low-tidal-volume group (18.1 +/- 3.1 vs. 12.0 +/- 2.8 h, P < 0.05, and 17.6 +/- 1.6 vs. 14.1 +/- 3.8 h, P < 0.05). Although the Pao2/Fio2 tended to be lower in the low- than in the high-tidal-volume group (P = 0.06), postmortem examination showed a lower lung tissue wet/dry ratio in the low- than in the high-tidal-volume group (7.1 +/- 0.5 vs. 9.1 +/- 0.7, P < 0.05). A low-tidal-volume ventilation strategy applied early during septic shock may be beneficial in terms of reducing the amount of lung edema and prolonging survival time.

Animals↗