Spatial and temporal changes in the morphology of preosteoblastic cells seeded on microstructured tantalum surfaces.

It has been widely reported that surface morphology on the micrometer scale affects cell function as well as cell shape. In this study, we have systematically compared the influence of 13 topographically micropatterned tantalum surfaces on the temporal development of morphology, including spreading, and length of preosteoblastic cells (MC3T3-E1). Cells were examined after 0.5, 1, 4, and 24 h on different Ta microstructures with vertical dimensions (heights) of 0.25 and 1.6 mum. Cell morphologies depended upon the underlying surface topography, and the length and spreading of cells varied as a function of time with regard to the two-dimensional pattern and vertical dimension of the structure. Microstructures of parallel grooves/ridges caused elongated cell growth after 1 and 4 h in comparison to a flat, nonstructured, reference surface. For microstructures consisting of pillars, cell spreading was found to depend on the distance between the pillars with one specific pillar structure exhibiting a decreased spreading combined with a radical change in morphology of the cells. Interestingly, this morphology on the particular pillar structure was associated with a markedly different distribution of the actin cytoskeleton. Our results provide a basis for further work toward topographical guiding of cell function.

Traumatic abdominal wall hernia--four cases and a review of the literature.

OBJECTIVE: To review blunt traumatic abdominal wall hernias (TAWHs) in our institution. METHOD: Retrospective review of blunt abdominal trauma cases over a 6-month period. RESULTS: Four patients with TAWH were identified. The mean age was 36 years. Three had been involved in vehicular collisions, and 1 had been assaulted with a large stone. All were diagnosed on presentation, 3 by computed tomography scan and 1 clinically. Two were repaired as emergencies, and 1 was repaired after 4 months. The 4th patient refused surgery. CONCLUSION: This uncommon injury requires a high index of suspicion and a low threshold for intervention. CT scan offers the best imaging potential.

Traumatic abdominal wall hernia - four cases and a review of the literature : trauma

Objective. To review blunt traumatic abdominal wall hernias (TAWHs) in our institution. Method. Retrospective review of blunt abdominal trauma cases over a 6-month period. Results. Four patients with TAWH were identified. The mean age was 36 years. Three had been involved in vehicular collisions; and 1 had been assaulted with a large stone. All were diagnosed on presentation; 3 by computed tomography scan and 1 clinically. Two were repaired as emergencies; and 1 was repaired after 4 months. The 4th patient refused surgery. Conclusion. This uncommon injury requires a high index of suspicion and a low threshold for intervention. CT scan offers the best imaging potential

Alleviation of murine leukemia virus repression in embryonic carcinoma cells by genetically engineered primer binding sites and artificial tRNA primers.

The primer binding site (PBS) plays pivotal roles during reverse transcription of retroviruses and also is the target of a cellular host defense impeding the transcription of murine leukemia virus (MLV) harboring a proline (pro) PBS in embryonic cells. Both the PBS and the tRNA primer are copied during reverse transcription and anneal as complementary DNA sequences creating the PBS of the integrated provirus. The pro PBS of MLV can be exchanged by PBS sequences matching endogenous or engineered tRNAs to allow replication of Akv MLV-derived vectors in fibroblasts. Here we use the PBS escape mutant B2 to demonstrate the capacity of the synthetic tRNA(B2) to function in reverse transcription in competition with endogenous tRNAs in fibroblasts and embryonic carcinoma (EC) cells. We further show symmetry between PBS and the primer by the ability of the synthetic tRNA(B2) to confer escape from EC repression of a PBS-Pro vector. Of a panel of vectors with the repressed pro PBS substituted for other natural or artificial PBS sequences, all except one efficiently expressed the neo marker gene when transferred to NIH/3T3 and EC cells, hence avoiding PBS-mediated silencing in EC cells. A non-natural PBS matching an artificially designed tRNA molecule conferred no further relief from repression than that attained with the B2 escape mutant or the natural alternative PBSs. Interestingly, a vector harboring a PBS matching tRNA(Lys1.2) suffered repression similar to the wild-type PBS-Pro but was partially rescued by a single point mutation of the PBS.

Lack of shielding of primer binding site silencer-mediated repression of an internal promoter in a retrovirus vector by the putative insulators scs, BEAD-1, and HS4.

A major determinant for transcriptional incompetence of murine leukemia virus (MLV) and MLV-derived vectors in embryonal cells is located at the proline primer binding site (PBS). The mechanism of silencing is unknown, yet the effect is capable of spreading to adjacent promoters. Based on a retroviral vector containing an internal promoter and the escape mutant B2 PBS with expressional capacity in embryonal cells, we have developed an assay to test the ability of putative insulators to shield the silencer at the PBS. Since the B2 PBS reverts to the wild-type PBS at high frequency, a shielding ability of a putative insulator can be assessed from the ratio of expressing B2 PBS to proline PBS proviruses in the target embryonal carcinoma cell population as measured by primer extension. Our results show that none of the possible insulators, scs, BEAD-1, or HS4, is able to shield an internal promoter from the repressive effect of the silencer at the PBS region when inserted between the silencer and the promoter.