Faculty Bibliography

PURPOSE: This study evaluated the bone mineral apposition rate (MAR) at the bone-implant interface region of alumina-blasted/acid-etched (AB/AE), plasma-sprayed hydroxyapatite (PSHA), and nanometric-scale bioceramic-coated surfaces at early implantation times in a dog tibia model. MATERIALS AND METHODS: Implants (n = 12 per group) with three different surfaces-AB/AE, PSHA, and a bioceramic coating in the 300- to 500-nm thickness range-were placed bilaterally along the proximal tibiae of six male beagles. Implants remained for 3 and 5 weeks in vivo. Ten and 2 days prior to euthanization, calcein green and oxytetracycline were administered for bone labeling. Following euthanization, the limbs were retrieved by sharp dissection and the implants and bone were processed nondecalcified into ~30-Mum-thick sections along the implant long axis. MAR was measured by the distance between bone labels over time at the interface region (to 0.5 mm from the implant surface) and at regions > 3 mm from the implant surface (remote site). A generalized linear mixed-effects analysis of variance model was conducted with significance levels set at .05. RESULTS: Irrespective of implant surface, the MAR at the interface region was significantly higher than the MAR at the remote site. Significant MAR differences in the interface region were observed between the different surfaces (PSHA > AB/AE > nano). CONCLUSIONS: Bone kinetics during early healing stages were influenced by implant surface modifications.

PURPOSE: To evaluate the biomechanical fixation, bone-to-implant contact (BIC), and bone morphology of screw-type root-form implants with healing chambers with as-machined or dual acid-etched (DAE) surfaces in a canine model. MATERIALS AND METHODS: The animal model included the placement of machined (n = 24) and DAE (n = 24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Following euthanasia, half of the specimens were subjected to biomechanical testing (torque to interface failure) and the other half were processed for histomorphologic and histomorphometric (%BIC) assessments. Statistical analyses were performed by one-way analysis of variance at the 95% confidence level and the Tukey post hoc test for multiple comparisons. RESULTS: At 4 weeks, the DAE surface presented significantly higher mean values for torque to interface failure overall. A significant increase in %BIC values occurred for both groups over time. For both groups, bone formation through the classic appositional healing pathway was observed in regions where intimate contact between the implant and the osteotomy walls occurred immediately after implantation. Where contact-free spaces existed after implantation (healing chambers), an intramembranous-like healing mode with newly formed woven bone prevailed. CONCLUSIONS: In the present short-term evaluation, no differences were observed in BIC between groups; however, an increase in biomechanical fixation was seen from 2 to 4 weeks with the DAE surface.

Traumatic injury to the retrohepatic veins continues to carry high mortality rates. In the last few decades various management strategies have been proposed. However, treatment of such injuries still remains highly variable and technically challenging due to the surgically inaccessible location of these vessels and the consequent difficulty controlling bleeding. We report a successful repair of complete transection of the two main extraparenchymal hepatic veins and laceration of the retrohepatic inferior vena cava using cardiopulmonary bypass (CPB) and hypothermic circulatory arrest (HCA) following blunt abdominal trauma. Immediate CPB with or without HCA can be life-saving and should be considered for patients with complex isolated retrohepatic venous injuries.

To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 muL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 muL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P < .05) and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

Recent advances in surgical management of lymphedema have provided options for patients who have failed conservative management with manual lymphatic massage and/or compression garments. The purpose of this review is to provide a historical background to the surgical treatment of lymphedema and how these options have evolved over time. In addition, we aim to delineate the various types of surgical approaches available, indications for surgery, and reported outcomes. Our goal is to increase awareness of these options and foster research to improve their outcomes.

Steel factor, the protein product of the Steel locus in the mouse, is a multifunctional signal for the primordial germ cell population. We have shown previously that its expression accompanies the germ cells during migration to the gonads, forming a "travelling niche" that controls their survival, motility, and proliferation. Here we show that these functions are distributed between the alternatively spliced membrane-bound and soluble forms of Steel factor. The germ cells normally migrate as individuals from E7.5 to E11.5, when they aggregate together in the embryonic gonads. Movie analysis of Steel-dickie mutant embryos, which make only the soluble form, at E7.5, showed that the germ cells fail to migrate normally, and undergo "premature aggregation" in the base of the allantois. Survival and directionality of movement is not affected. Addition of excess soluble Steel factor to Steel-dickie embryos rescued germ cell motility, and addition of Steel factor to germ cells in vitro showed that a fourfold higher dose was required to increase motility, compared to survival. These data show that soluble Steel factor is sufficient for germ cell survival, and suggest that the membrane-bound form provides a higher local concentration of Steel factor that controls the balance between germ cell motility and aggregation. This hypothesis was tested by addition of excess soluble Steel factor to slice cultures of E11.5 embryos, when migration usually ceases, and the germ cells aggregate. This reversed the aggregation process, and caused increased motility of the germ cells. We conclude that the two forms of Steel factor control different aspects of germ cell behavior, and that membrane-bound Steel factor controls germ cell motility within a "motility niche" that moves through the embryo with the germ cells. Escape from this niche causes cessation of motility and death by apoptosis of the ectopic germ cells.