Validation of a finite element model of the Kirschner-Ehmer external skeletal fixation system.

Objective: To determine the validity of finite element analysis (FEA) as a means of examining biomechanical properties of the Kirschner-Ehmer external skeletal fixation system.

Sample Population: 10 paired tibiae harvested from skeletally mature dogs weighing between 30 and 38 kg immediately following euthanasia for reasons unrelated to musculoskeletal disease.

Procedure: A gap fracture was created in each bone; fragments were stabilized with 3 frame configurations (type I, type II, and type III), using enhanced-profile threaded pins.

Replication of injected DNA templates in Xenopus embryos.

We have analysed the replication of both exogenous frog DNAs and heterologous DNAs during development from the first cleavage through the blastula stage, by their microinjection into fertilized eggs of Xenopus laevis. The data show that various plasmids increase to different extents and that the differences cannot be attributed to size alone. Plasmids containing the Xenopus ribosomal gene repeat unit do not replicate efficiently, and they also inhibit the replication of co-injected DNA templates.

Distribution, expression and germ line transmission of exogenous DNA sequences following microinjection into Xenopus laevis eggs.

We analysed the fate, expression and germ line transmission of exogenous DNA which was microinjected into fertilized eggs of Xenopus laevis. DNA was injected into fertilized eggs within 1 h following fertilization. The injected DNA was dispersed around the site of injection and became localized to cleavage nuclei by stage 6.

Replication, integration and expression of exogenous DNA injected into fertilized eggs of Xenopus laevis.

We have analyzed the fate of circular and linear DNA molecules following microinjection into the cytoplasm of fertilized eggs of Xenopus laevis. Recombinant plasmids containing sea urchin histone genes (pSp 102), Drosophila ADH genes (sAC-1), and SV40 (SV2 CAT) replicate during the development of the injected frog embryo. In contrast, pBR322 either as monomers or multimers does not appear to replicate as efficiently.