Faculty Bibliography

To investigate the effects of histone methyltransferase ESET (also known as SETDB1) on bone metabolism, we analyzed osteoblasts and osteoclasts in ESET knockout animals, and performed osteogenesis assays using ESET-null mesenchymal stem cells. We found that ESET deletion severely impairs osteoblast differentiation but has no effect on osteoclastogenesis, that co-transfection of ESET represses Runx2-mediated luciferase reporter while siRNA knockdown of ESET activates the luciferase reporter in mesenchymal cells, and that ESET is required for postnatal expression of Indian hedgehog protein in the growth plate. As the bone phenotype in ESET-null mice is 100% penetrant, these results support ESET as a critical regulator of osteoblast differentiation during bone development.

Bone is a viscoelastic connective tissue composed primarily of mineral and type I collagen, which interacts with water, affecting its mechanical properties. Therefore, both the level of hydration and the loading rate are expected to influence the measured nanomechanical response of bone. In this study, we investigated the influence of three distinct hydration conditions, peak loads and loading/unloading rates on the elastic modulus and hardness of canine femoral cortical bone via nanoindentation. Sections from three canine femurs from multiple regions of the diaphysis were tested for a total of 670 indentations. All three hydration conditions (dry, moist and fully hydrated tissue) were tested at three different loading profiles (a triangular loading profile with peak loads of 600, 800 and 1000muN at loading/unloading rate of 60, 80 and 100muN/s, respectively; each test was 20s in duration). Significant differences were found for both the elastic modulus and hardness between the dry, moist and fully hydrated conditions (p0.05). However, in both the moist and fully hydrated conditions, the elastic modulus and hardness were significantly different under all loading profiles (with the exception of the moist condition at the 600- and 800-muN peak load). Given these findings, it is critical to perform nanoindentation of bone under fully hydrated conditions to ensure physiologically relevant results. Furthermore, this work found that a 20-s triangular loading/unloading profile was sufficient to capture the viscoelastic behavior of bone in the 600- to 1000-muN peak load range. Lastly, specific peak load values and loading rates need to be selected based on the structural region for which the mechanical properties are to be measured.

BACKGROUND: A 270-degree partially tubed pectoralis major myocutaneous flap (PMMF) is an excellent option for total circumferential pharyngoesophageal defects in patients who are not candidates for more complex reconstructions. METHODS: Patients undergoing circumferential pharyngoesophageal reconstruction with partially tubed PMMF were reviewed. End points were stricture, fistula, resumption of oral intake, perioperative death, and recurrence. RESULTS: Eleven patients underwent 270-degree PMMF for reconstruction: 6 (55%) were men and 5 (45%) were women (mean, 62 years; range, 42-78 years). Three patients (27%) developed fistulas and 2 (18%) developed stenosis. Ten patients (91%) were able to resume adequate nutrition via oral intake. There were no perioperative deaths. CONCLUSIONS: Patients with severe comorbidities, metastatic disease, a lack of donor vessels, or a potentially hostile abdomen may not be ideal candidates for free tissue transfer. For these patients, partially tubed PMMF using the prevertebral fascia provides a reliable alternative for reconstruction with excellent functional results.

PURPOSE/OBJECTIVE:Peripheral tissue oxygen saturation (Sto2) has shown promise as an early indicator of tissue hypoperfusion and as a risk stratification tool in various forms of shock. The purpose of this study was to determine if Sto2 would predict admission to an intensive (ICU) or progressive care unit in patients with early signs of sepsis. METHODS:In this prospective observational study, a rapid response team measured Sto2 levels in patients screening positive for sepsis. Using a logistic regression model, the value of Sto2 as a predictor for ICU admission within 72 hours of the initial assessment was determined. RESULTS:The 31 (47%) of 66 patients who required ICU admission within 72 hours of evaluation had a significantly lower Sto2 value (median, 78% vs 81%; P = .05). All patients with Sto2 less than 70% required ICU admission. A 1-point increase in Sto2 was associated with a 7% decrease in the odds of requiring ICU admission, and the area under the curve for Sto2 was 0.64 (0.51-0.77, P = .01). CONCLUSIONS:Low Sto2 levels in patients screening positive for sepsis are associated with an increased risk of ICU admission, but their reliability as a predictor is rather low. An Sto2 below 70% might be an interesting cutoff value for further study.

OBJECTIVE: The main objective of this in vivo study was to determine the incidence and location of fracture in round nickel-titanium (NiTi) and round stainless steel orthodontic archwires, both commonly used in orthodontics. Secondarily, this study sought to determine if there is any correlation between archwire fracture and gender, diameter of the archwire, arch type (maxillary/mandibular) or bracket used. DESIGN: In vivo study. MATERIALS AND METHODS: One thousand orthodontic patients (1434 archwires) were evaluated during regular treatment visits to assess archwire fracture and location. The patient's gender, age, type of archwire (round NiTi and round stainless steel), diameter of the archwire, arch type, location of fracture (anterior or posterior) and period of service before fracture were recorded. STATISTICAL ANALYSIS: Chi-square statistical test was utilized to address the frequency and the correlation between the different variables. Level of statistical significance (alpha) was set at 0.05. RESULTS: Twenty-five archwire failures were reported (1.7%) of the total sample size. All fractured archwires were NiTi, and 76% of the fractures were located in the posterior region. No statistical significance was found between archwire fracture and gender, arch type (maxillary/mandibular), archwire diameter or bracket type. CONCLUSION: The frequency of archwire fracture during regular orthodontic visits is very low. The most common archwire fracture site is the posterior region. NiTi wires are the most commonly fractured archwire. No statistically significant correlation exists between archwire fracture and gender, arch type, bracket type or diameter of archwire.

Conventional reconstructive procedures for face and scalp reconstruction fall short of aesthetic and functional goals because of the unique quality and quantity of facial and scalp soft tissue. The purpose of this cadaver study was to demonstrate the feasibility of a flap design for full face and scalp composite tissue allotransplantation, without cutaneous facial scars. Six fresh human cadavers were dissected with sagittal scalp and mucosal incisions for full face and scalp harvest without cutaneous facial incisions. Sub-galeal and sub-SMAS dissection allowed for inclusion of the external carotid and internal jugular systems. Time of facial-scalp flap harvesting, length of the arterial and venous pedicles, length of sensory nerves (that were included in the facial flaps) and approximate surface area of the flaps were measured. Three of six flaps were transferred to recipient cadavers and the time of transfer was recorded. As a proof of concept, the external carotid arteries of one of six cadavers was flushed to remove clots and perfused with a radio-opaque latex polymer, Microfil (Flow Tech Inc.), to study flap perfusion by X-ray imaging. In the donor cadaver, the mean harvesting time of the total facial-scalp flap was 105 +/- 19 minutes. The mean length of the supraorbital, infraorbital, mental and great auricular nerves were 1.3 +/- 0.2, 1.3 +/- 0.1, 1.3 +/- 0.1, and 4.8 +/- 0.6 cm, respectively. The mean length of the external carotid artery and external jugular vein were 8.7 +/- 0.3 and 9.2 +/- 0.4 cm, respectively. The approximate area of the harvested flap was 1063 +/- 60 cm(2). In preparation for full face and scalp allotransplantation in humans, this study has demonstrated the feasibility of a full face and scalp flap without visible facial incisions.

PURPOSE:: Commercial implants differ at macro-, micro-, and nanolevels, which makes it difficult to distinguish their effect on osseointegration. The aim of this study was to evaluate the early integration of 5 commercially available implants (Astra OsseoSpeed, Straumann SLA, Intra-Lock Blossom Ossean, Nobel Active, and OsseoFix) by histomorphometry and nanoindentation. MATERIALS AND METHODS:: Implants were installed in the tibiae of 18 beagle dogs. Samples were retrieved at 1, 3, and 6 weeks (n = 6 for each time point) and were histologically and nanomechanically evaluated. RESULTS:: The results presented that both time (P < 0.01) and implant system and time interaction (P < 0.02) significantly affected the bone-to-implant contact (BIC). At 1 week, the different groups presented statistically different outcomes. No significant changes in BIC were noted thereafter. There were no significant differences in rank elastic modulus (E) or in rank hardness (H) for time (E: P > 0.80; H: P > 0.75) or implant system (E: P > 0.90; H: P > 0.85). CONCLUSIONS:: The effect of different implant designs on osseointegration was evident especially at early stages of bone healing.

OBJECTIVES: Bone formation and maintenance around implants placed immediately after tooth extraction may be affected by implant surface treatment and compromise long-term esthetic results. This study morphometrically evaluated buccal bone loss and bone-to-implant contact (BIC) of four implant systems placed immediately after tooth extraction in a dog model. MATERIAL AND METHODS: The premolars of eight beagle dogs were bilaterally extracted with a full-thickness flap, and root-form dental implants were placed on the root extraction socket. Implants (n = 16 each) with different surface treatments were placed from sites 1 to 4 and alternated between animals to allow evaluation of the same number of implants at sites and evaluation time points. Implant surface treatments were as follows: anodized, discrete crystalline deposition, SLActive, and microblasted. The left and right side provided implants that stayed for 2 and 4 weeks, respectively. Submerged healing was allowed and bone-to-implant contact (BIC) and buccal bone loss were morphometrically measured. Linear mixed models (P < 0.05) were used to assess differences between groups, across time, and their interaction. RESULTS: Buccal bone loss was observed to approximately double between 2 and 4 weeks (P = 0.01). BIC also increased between 2 and 4 weeks, by 20-25% (P = 0.01). These changes were statistically similar for each surface. CONCLUSION: When placed immediately after tooth extraction, the evaluated histomorphometric parameters vary only with time.

Behcet's disease (BD) is an autoimmune & autoinflammatory disease of unclear etiology characterized by recurrent oral & genital ulcers as well as other systemic manifestations. A key pathogenesis is excessive inflammatory wound healing response. While descriptions of the cutaneous manifestations of disease are limited to short-term consequences such as extensive pustule and papule formation in response to minor tissue injury, the long-term consequences are significant fibrosis and scarring of epithelial tissue. We describe the case of a patient with Behcet's disease who presented with unilateral facial atrophy secondary to minor trauma to the oral mucosa. She was treated with autologous fat grafting. Though a rare disease, plastic surgeons should be aware of the entity of Behcet's disease and its complications of tissue atrophy that may require reconstructive surgery.