No abstract

Fetal rabbit wounds that are sutured show excellent repair without obvious scarring. In contrast, an unsutured wound in a rabbit fetus does not close, and it appears that the process of wound contraction does not occur. Experiments were carried out to illustrate the mechanisms responsible for the noncontraction of open fetal rabbit wounds. Results showed that the lack of wound contraction was not an artifact caused by rapid fetal growth. With regard to the ability of cultured fetal fibroblasts to show cytoplasmic muscle-induced cell contraction, we found that, in cultured fetal fibroblasts, cell contraction was induced by adenosine triphosphate. Contractile abilities of fetal-derived fibroblasts were equivalent to those of adult-derived fibroblasts. The fetal fibroblasts also demonstrated the generation of superior contractile activity when examined in a fibroblast-populated collagen lattice model. Finally, the ability of amniotic fluid to alter wound contraction was addressed by means of the fibroblast-populated collagen lattice in vitro model. Increasing concentrations of amniotic fluid inhibited fetal fibroblast lattice contraction. Therefore, rabbit amniotic fluid contains an inhibitor that may be partially responsible for the noncontraction of fetal rabbit wounds in utero.

No abstract

A venous embolism model with autogenous thrombus was used for comparison of the functional properties of two new vena caval devices: a titanium Greenfield filter and the bird's nest filter. All nine Greenfield filters were correctly placed in the inferior vena cava and produced significant clot lysis of 81.3% +/- 16.3% (p less than 0.001, paired t test). Difficulty was encountered in affixing the hooks of the bird's nest device into the vein wall and resulted in two filters not being inserted and two filters being placed too proximally. One set of hooked wires of another bird's nest device migrated to the right atrium despite correct insertion. Eight bird's nest devices allowed clot lysis of 83.4% +/- 17.7% (p less than 0.001), paired t test) but thrombus size was increased in one case. The Greenfield and bird's nest filters have comparable effects on trapped emboli, but the bird's nest filter may be susceptible to thrombosis and occlusion under certain circumstances. The pre-shaped hooked wires of the bird's nest device may be difficult to insert and may allow proximal migration after a large thrombus was trapped.