Assessment of the Efficacy of the Bio-Absorbable Oxidized Regenerated Cellulose for Prevention of Post-Operative Pericardial Adhesion in the Rabbit Model

Pericardial adhesions complicate re-operative cardiac surgery and several attempts have been made to reduce adhesion formation. The efficacy of bio-absorbable oxidized regenerated cellulose in preventing post-operative pericardial adhesions was evaluated in the present study. Forty New Zealand white rabbits were divided into four groups of 10. In all rabbits an area of pericardium (2 × 2 cm) was excised. The wound was left open in groups 1 and 2 but replaced with bio-absorbable oxidized regenerated cellulose in groups 3 and 4. Rabbits in groups 1 and 3 were killed 3 weeks after surgery and those in groups 2 and 4 were killed at 6 weeks. Groups 1 and 2 showed more severe pericardial adhesions, more fibrous reaction and increased visibility of coronary vessels than groups 3 and 4, although there was no difference in inflammation. Light microscopy showed a mesothelium-like cell layer in groups 3 and 4. It is concluded that bio-absorbable oxidized regenerated cellulose may be suitable in patients receiving staged cardiac surgery and in those with a high probability of re-operation.

Synthesis and release of dopamine in rat striatal slices: requirement for exogenous tyrosine in the medium

When incubated in a tyrosine-free medium, the tissue dopamine (DA) level of rat striatal slices increased by about 921 +/- 15 pmol/mg protein during 90 min of preincubation. In contrast, the tissue-free tyrosine level declined only 130 pmol/mg protein in the same assay period. Depolarization of the slices with high K+ increased both DA and DOPAC outputs and depleted tissue DA level by about 75%. Although 60 min of resting after high K+ depolarization significantly restored the tissue DA levels, neither this restoration nor depolarization-induced DA release was altered by exogenous tyrosine. Similarly, failure of exogenous tyrosine was also observed during three successive depolarization periods of striatal slices. These results indicate that nigrostriatal dopaminergic neurons are able to synthesize and release the DA in the absence of exogenous tyrosine in the medium. Since the free tyrosine level in the slices does not seem to be a sufficient source, it is likely that tyrosine mobilized from its bound source(s) supports the DA synthesis under in vitro experimental conditions.