ABSTRACT
Modular neck femoral stems have a higher-than-anticipated rate of failure in registry results, but large single-center cohort studies are lacking. This is a retrospective cohort of 152 hips implanted with a single titanium stem with a modular titanium neck, presenting clinical, radiographic, and metal ion results at a mean 4.5-year follow-up. Five hips were revised during the study period, for an overall Kaplan-Meier survival of 0.894 at 8 years. There was one modular neck fracture (0.66%), but others demonstrated corrosion or adverse tissue reaction. Serum metal levels demonstrated wide variability. Despite good clinical results in the majority of patients, we confirmed an increased rate of femoral revision at mid-term follow-up, and therefore urge caution in the use of this particular stem design.
Subject(s)
Arthroplasty, Replacement, Hip/adverse effects , Arthroplasty, Replacement, Hip/methods , Hip Prosthesis/adverse effects , Osteoarthritis, Hip/surgery , Prosthesis Failure/etiology , Titanium/blood , Adult , Aged , Aged, 80 and over , Arthroplasty, Replacement, Hip/mortality , Cohort Studies , Corrosion , Female , Femur Neck/diagnostic imaging , Femur Neck/surgery , Hip Joint/diagnostic imaging , Hip Joint/surgery , Humans , Ions/blood , Kaplan-Meier Estimate , Male , Middle Aged , Osteoarthritis, Hip/mortality , Prosthesis Design , Radiography , Reoperation , Retrospective Studies , Young AdultABSTRACT
FIZ1 (Flt-3 Interacting Zinc-finger) interacts and co-purifies with the rod-specific transcription factor NRL (Neural Retina Leucine zipper). We hypothesize that FIZ1 is part of an interface between cell-specific factors, like NRL, and more ubiquitous regulatory networks that vary the absolute expression levels of some rod-specific genes (i.e. Rhodopsin). As part of an ongoing exploration of FIZ1's role in neural retina, in vivo, we have taken the first look at FIZ1 expression in the developing mouse retina during the retinal maturation period. Using the normal C57B6 mouse as a model, multiple approaches were used including: immunoblotting, immunohistochemistry, and quantitative real-time PCR. Functional implications of FIZ1/NRL interaction, on NRL- and CRX-mediated activation of the Rhodopsin (Rho) and cGMP-phosphodiesterase beta-subunit gene (PDE6B) promoters, were examined by co-transfection assays. Immunoblot analysis revealed that FIZ1 protein levels were lowest in immature mouse neural retina (P0). FIZ1 concentration increased at least ten-fold as the neural retina matured to the adult state (P21 and later). Immunohistochemical comparison of immature post-natal and mature adult retina revealed increasing FIZ1 protein in photoreceptors, the inner plexiform layer, and the ganglion cell layer. Total retinal Fiz1 mRNA content increased as the neural retina matured. The expected increase in Rho mRNA level was also monitored as a genetic marker of photoreceptor maturation. In transient co-transfection assays of CV1 cells, FIZ1 synergized with NRL to activate transcription from the Rho and PDE6B gene promoters with some differences. In the case of the Rho promoter, FIZ1 synergized when both NRL and CRX were present. With the PDE6B promoter, FIZ1 synergized with NRL alone, and the inclusion of CRX decreased this synergy. These findings support previous evidence that FIZ1 is present in rod-photoreceptors (co-immunoprecipitation from nuclear-protein extracts with rod-specific NRL). FIZ1 expression increases in the neural retina during the retinal maturation period. Additionally, in vitro experiments demonstrate that FIZ1 has the potential to significantly increase the NRL-mediated activation of photoreceptor-specific promoters. While CRX is not a strong activator of the PDE6B promoter, alone or with NRL, CRX decreased the synergy of NRL with FIZ1.
