Ensuring success in alveolar bone grafting: a three-dimensional approach

Alveolar bone grafting is an integral part of correcting dental arch interruption in those with cleft lip and palate. Often included within a combination of treatment modalities, alveolar grafting must be conducted in a technically effective manner and at the appropriate stage of development in order to maximize outcome and avoid morbidity. Although much regarding this procedure remains unclear, continued research and experience has provided several key insights. Bone grafting appears optimal between maxillary growth completion and maxillary canine eruption (usually between 8 and 10 years of age). Coordination of efforts and planning between surgeon and orthodontist is imperative. Correction of the alveolar defect helps not only restores dental arch continuity, but also supports the nasal base, stabilizes the maxilla, and restores volume to the lip. Appreciation of the 3-dimensional nature of the defect helps to reliably correct the defect in an anatomically correct fashion. Optimization of soft tissue, bony, and, periodontal conditions adjacent to the cleft help maximize the likelihood of success. Staging of the procedure is often necessary to maximize outcome and avoid unnecessary procedures. Here, we review several variables of alveolar bone grating based on current literature as well as our own experience.     

Muscle activity,cross-sectional area,and density following passive standing and whole body vibration: A case series

Objective

To investigate the effects of intermittent passive standing (PS) and whole body vibration (WBV) on the electromyography (EMG) activity, cross-sectional area, and density of lower extremity muscles in individuals with chronic motor complete spinal cord injury (SCI).

Design

Case series.

Methods

Seven adult men with chronic (≥2 years), thoracic motor complete (AIS A–B) SCI completed a 40-week course of thrice-weekly intermittent PS-WBV therapy, in a flexed knee posture (160°), for 45 minutes per session at a frequency of 45 Hz and 0.6–0.7 mm displacement using the WAVE^® Pro Plate, with an integrated EasyStand™ standing frame. EMG was measured in major lower extremity muscles to represent muscle activity during PS-WBV. The cross-sectional area and density of the calf muscles were measured using peripheral quantitative computed tomography at the widest calf cross-section (66% of the tibia length) at pre- and post-intervention. All measured variables were compared between the pre- and post-intervention measurements to assess change after the PS-WBV intervention.

Results

PS-WBV acutely induced EMG activity in lower extremity muscles of SCI subjects. No significant changes in lower extremity EMG activity, muscle cross-sectional area, or density were observed following the 40-week intervention.

Conclusions

Although acute exposure to PS-WBV can induce electrophysiological activity of lower extremity muscles during PS in men with motor complete SCI, the PS-WBV intervention for 40 weeks was not sufficient to result in enhanced muscle activity, or to increase calf muscle cross-sectional area or density.     

Hair Mercury and Fish Consumption in Residents of O‘ahu,Hawai‘i

Recent studies have established that men are susceptible to cardiotoxicity from methylmercury exposure, which also poses risks to the pregnant woman. Hair samples were obtained and questionnaires for methylmercury exposure assessment were administered to 110 adults (57 men, 53 women) throughout O‘ahu, Hawai‘i during December 2010 to January 2011. Hair samples were analyzed for total mercury with a direct mercury analyzer. Men ≥ 46 years had a median of 2.0 µg/g, which was above the reference dose of 1 µg/g, as compared to younger men with a median 1.0 µg/g (P < 0.05). Hair concentrations from older women had a median of 1.2 µg/g of mercury compared to 0.6 µg/g for younger women. Additionally, 38% of women of childbearing age had a Hazard Index > 1.0. This indicates that both men and women were at risk for excessive methylmercury exposure. In the final regression model, male gender, age > 45 years, length of residency > 10 years in Hawai‘i, and fish consumption frequency > 1 meal per week were significant factors in increased hair mercury levels. Following safe fish consumption practices allows residents to reap health benefits of fish consumption without excessive toxicant exposure.     

Optimizing dose and scheduling of filgrastim (granulocyte colony- stimulating factor) for mobilization and collection of peripheral blood progenitor cells in normal volunteers [see comments]

To define an optimal regimen for mobilizing and collecting peripheral blood progenitor cells (PBPC) for use in allogeneic transplantation, we evaluated the kinetics of mobilization by filgrastim (recombinant met- human granulocyte colony-stimulating factor [r-metHuG-CSF]) in normal volunteers. Filgrastim was injected subcutaneously for up to 10 days at a dose of 3 (n = 10), 5 (n = 5), or 10 micrograms/kg/d (n = 15). A subset of volunteers from each dose cohort underwent a 7L leukapheresis on study day 6 (after 5 days of filgrastim). Granulocyte-macrophage colony-forming cell (GM-CFC) numbers in the blood were maximal after 5 days of filgrastim; a broader peak was evident for CD34+ cells between days 4 and 6. The 95% confidence intervals (CI) for mean number of PBPC per milliliter of blood in the three dose cohorts overlapped on each study day. However, on the peak day, CD34+ cells were significantly higher in the 10 micrograms/kg/d cohort than in a pool of the 3 and 5 micrograms/kg/d cohorts. Mobilization was not significantly influenced by volunteer age or sex. Leukapheresis products obtained at the 10 micrograms/kg/d dose level contained a median GM-CFC number of 93 x 10(4)/kg (range, 50 x 10(4)/kg to 172 x 10(4)/kg). Collections from volunteers receiving lower doses of filgrastim contained a median GM- CFC number of 36 x 10(4)/kg (range, 5 x 10(4)/kg to 204 x 10(4)/kg). The measurement of CD34+ cells per milliliter of blood on the day of leukapheresis predicted the total yield of PBPC in the leukapheresis product (r = .87, P < .0001). Assuming a minimum GM-CFC requirement of 50 x 10(4)/kg (based on our experience with autologous PBPC transplantation), all seven leukapheresis products obtained at the 10 micrograms/kg/d dose level were potentially sufficient for allogeneic transplantation purposes. We conclude that in normal donors, filgrastim 10 micrograms/kg/d for 5 days with a single leukapheresis on the following day is a highly effective regimen for PBPC mobilization and collection. Further studies are required to determine whether PBPC collected with this regimen reliably produce rapid and sustained engraftment in allogeneic recipients.     

Generation of normal human red cell volume, hemoglobin content, and membrane area distributions by "birth" or regulation?

Using flow cytometry and osmotic lysis measurements, we document here the means and coefficients of variation of the following red cell (RBC) properties: hemoglobin (Hb) content, volume, Hb concentration, and relative lytic tonicity distributions in populations of normal human RBCs, before and after density fractionation. The distributions showed a pattern characterized by much larger coefficients of variation of the Hb content and volume distributions than of the Hb concentration and relative lytic tonicity distributions. From analysis of the factors that determine those RBC properties, the patterns were interpreted as reflecting previously unrecognized statistical proportionalities between cell osmolyte content, Hb content, and membrane area. The possible origin of these statistical links was analyzed by considering alternative models with and without the participation of regulatory processes during cell maturation. A model was shown to be feasible in which mature RBC variability with proportional volume, area, and Hb content arises solely from cell size variability at the last erythroid cell division.     

Murine Hertwig's anemia: premature death after normal bone marrow transplantation is radiation dose-dependent

Marrow transplantation therapy in mice with heritable blood disorders usually leads to rapid blood cell normalization, but is sometimes followed by pancytopenia and premature death. This is especially true in mice with Hertwig's anemia (an/an). Unlike the +/+ recipients, 100% of whom survive for over a year, 66% of the mutant mice die by 6 months posttransplantation, and the rest die soon thereafter. It is not clear whether premature death is due to the radiation dose (10 Gy) or to the fact that the F1 mutant mice receive parental-type cells known to induce hybrid resistance. In the present report, experiments were designed to determine whether the F1-an/an host is more sensitive to radiation and/or resistant to continued expansion of the parental-type +/+ cells. The mutant mice are, indeed, more sensitive to irradiation, with an LD100/30 of 7 Gy as compared with an LD100/30 of 10 Gy for the +/+ mice. The times of anemia onset and death for mutant mice implanted with +/+ cells postirradiation is also radiation dose-dependent. Further evidence that death is due to host radiation damage rather than F1 hybrid resistance was provided by transplanting cells from three morbid 10 Gy-irradiation recipients into unirradiated, anemic, stem cell-deficient, F1-W/Wv secondary hosts. All recipients were repopulated by the original parental cells, were cured of their anemia, and survived for 52 weeks posttransplantation. The an/an mouse's heightened susceptibility to radiation damage appears to be the major factor in early death after transplantation therapy.     

Expression of bcr-abl abrogates factor-dependent growth of human hematopoietic M07E cells by an autocrine mechanism

The introduction of a retrovirus vector expressing p210bcr-abl (P210) into the human factor-dependent cell line M07E resulted in the rapid outgrowth of factor-independent cells. Early after infection, four factor-independent clones were isolated and analyzed in greater detail along with mass populations obtained from separate infections. High levels of P210 tyrosine kinase activity were measured in the factor- independent cells. The mass populations and three of the four clones remained responsive to exogenous growth factors. Concentrated conditioned media isolated from the factor-independent populations and from all clones contained biologically active granulocyte-macrophage colony-stimulating factor (GM-CSF); interleukin-3 (IL-3) was detected at low levels in the mass population and in two of the clones. Neutralizing antibodies to IL-3, GM-CSF, and mast cell growth factor inhibited proliferation of the factor responsive clones by 60% to 90%. These results indicate that the growth autonomy of the P210-expressing M07E cells was acquired via an autocrine mechanism. In addition to factor-independent growth, P210-expressing M07E cells readily acquired a more mature megakaryocytic phenotype compared with control M07E cells. These data provide experimental evidence that expression of P210 tyrosine kinase in human hematopoietic cells induced growth factor secretion resulting in a pleiotropic effect on growth factor dependence and differentiation.