Molecular assessment of endosseous implant adherent cellular phenotypes in man

This investigation considered the role of implant surface roughness on activation of osteoblastic differentiation of uncommitted mesenchymal stem cells in humans. The aim of this study was to examine the gene expression profiles from adherent cells on moderately roughened TiO2 grit-blasted (micron-scale topography) and hydrofluoric acid modified TiO2 grit-blasted (nano-scale topography) implants. Sixty cpTitanium implants were placed and allowed to integrate for 24 hours, 72 hours, and one week in 10 systemically healthy patients. These implants were retrieved and biochemical analyzed by RT-PCR for markers of osteoblastic differentiation. A complex array of gene changes representative of osteogenesis was observed at both implant surfaces. Compared to implants with micron-scale topography, nano-scale topography implants supported greater expression of RUNX-2(1.6 vs. 2.6-fold,p=0.18), Osterix(1.8 vs. 3.9-fold,p=0.04), BSP(2.7 vs. 4.6-fold, p=0.11) and OCN(1.6 vs. 3.2-fold,p=0.06) mRNAs indicating greater osteogenesis at 7 days in vivo. Further investigations using this model may elucidate important difference among subsets of patients who experience implant failure

The influence of 1α.25-dihydroxyvitamin D3 coating on implant osseointegration in the rabbit tibia

Objectives: This study aims to evaluate bone response to an implant surface modified by 1α,25-dihydroxyvitamin D3 [1.25-(OH)2D3] in vivo and the potential link between 1.25-(OH) 2D3 surface concentration and bone response. Material and Methods: Twenty-eight implants were divided into 4 groups (1 uncoated control, 3 groups coated with 1.25-(OH)2D3 in concentrations of 10-8, 10-7 and 10-6 M respectively), placed in the rabbit tibia for 6 weeks. Topographical analyses were carried out on coated and uncoated discs using interferometer and atomic-force-microscope (AFM). Twenty-eight implants were histologically observed (bone-to-implant-contact [BIC] and new-bone-area [NBA]). Results: The results showed that the 1.25-(OH)2D3 coated implants presented a tendency to osseointegrate better than the non-coated surfaces, the differences were not significant (P > 0.05). Conclusions: The effect of 1.25-(OH)2D3 coating to implants suggested possible dose dependent effects, however no statistical differences could be found. It is thought that the base substrate topography (turned) could not sustain sufficient amount of 1.25-(OH)2D3 enough to present significant biologic responses. Thus, development a base substrate that can sustain 1.25-(OH)2D3 for a long period is necessary in future studies

Test-retest reliability and predictive validity of a juvenile guide dog behavior test

The ability to measure stable and consistent behavioral traits in dogs would facilitate selection and assessment of working dogs, such as guide dogs. Ideally, these measures should predict suitability for the working role from a young age. This study assessed test-retest reliability of a juvenile guide dog behavior test and predictive validity using qualification or withdrawal from guide dog training. Ninety-three guide dog puppies (52 female; 41 male) were tested at 5 (mean 4.78; ±0.73 SD) and 8 (mean 7.98; ±0.78 SD) months of age. The dogs were exposed to a sequence of 11 stimuli designed to assess the dogs’ reactions to meeting a stranger, obedience commands, body sensitivity, scavenging, and “animal” and human distractions. The behavior of dogs was digitally recorded and analyzed using an ethogram incorporating both frequency of behavior and specific reactions to stimuli. Test-retest reliability indicated interindividual consistency in many of the behavioral measures such as jumping, barking, and “low” greeting posture, as defined in our ethogram. Behavior measures that did not show interindividual consistency between tests included obedience responses, lip licking, body shaking, and scratching. Binary logistic regression models revealed 7 behavioral measures at 5 months and 5 measures at 8 months that were significantly associated with qualification or withdrawal. Uncorrelated measures and principal component scores of correlated measures were combined in a logistic regression model that showed great potential for predicting the probability of a dog qualifying or being withdrawn from guide dog training