Faculty Bibliography

OBJECTIVE: To evaluate the effects of clinically relevant variables on the maximum principal stress (MPS) in the veneer layer of an anatomically correct veneer-core-cement-tooth model. METHODS: The average dimensions of a mandibular first molar crown were imported into CAD software; a tooth preparation was modeled by reducing the proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. 'Crown systems' were composed by varying characteristics of a cement layer, structural core, and veneer solid, all designed to fit the tooth preparation. The main and interacting effects of proximal wall height reduction, core material, core thickness, cement modulus, cement thickness, and load position on the maximum stress distribution were derived from a series of finite element models and analyzed in a factorial analysis of variance. RESULTS: The average MPS in the veneer layer over the 64 models was 488 MPa (range = 248-840 MPa). MPS increased significantly with the addition of horizontal load components and with increasing cement thickness. In addition, MPS levels varied as a function of interactions between: proximal wall height reduction and load position; load position and cement thickness; core thickness and cement thickness; cement thickness and proximal wall height reduction; and core thickness, cement thickness and proximal wall height reduction. CONCLUSION: Rational design of veneered structural ceramics must consider the complex geometry of the crown-tooth system and integrate the influence of both the main effects and interactions among design parameters

Vascularized nerve grafts (VNG) were introduced in 1976 but since then, there have been no reports of their usage in lower extremity reconstruction systematically. The factors influencing outcomes as well as a comparison with conventional nerve grafts will be presented.Since 1981, 14 lower extremity nerve injuries in 12 patients have been reconstructed with VNG. Common peroneal nerve was injured in 12 and posterior tibial nerve in 5 patients. The level of the injury was at the knee or thigh. Twelve sural nerves were used as VNG with or without concomitant vascularized posterior calf fascia.All patients regained improved sensibility and adequate posterior tibial nerve function. For common peroneal nerve reconstructions, all patients with denervation time less than 6 months regained muscle strength of grade at least 4, even when long grafts were used for defects of 20 cm or more. Late cases, yielded inadequate muscle function even with the use of VNG.Denervation time of 6 months or less was critical for reconstruction with vascularized nerve graft. Not only the results were statistically significant compared with late cases, but also all early operated patients achieved excellent results. VNG are strongly recommended in traction avulsion injuries of the lower extremity with lengthy nerve damage

Soft-tissue reconstruction of traumatic patella and proximal tibial defects is challenging. Pedicled perforator-based adipocutaneous rotation flaps are a versatile local option as they have axial perfusion and greater freedom of transposition compared with random-pattern flaps, and replace the ideal tissue properties of this anatomic region.Experimental: Anatomic dissections were performed on 15 fresh cadaver legs and location of the dominant perforator measured. Clinical: A retrospective review was conducted at the University of Maryland/R Adams Cowley Shock Trauma Center evaluating patients over a 3-year period.Experimental: Cadaver dissections confirmed a principal perforator at 11.4 +/- 1.6 cm inferior to the patella. This vessel is consistently suitable in length and caliber for large rotation flap design. Clinical: Anterior tibial artery perforator flaps were performed on 4 patients following Gustilo IIIB wounds to the patella and tibial plateau. Two patients had rotation flap reconstructions to salvage failed gastrocnemius muscle flaps. All flaps were successful, however, one patient had overwhelming hardware infection several months later despite successfully healed flap.Local anterior tibial artery perforator flaps based on predictable perforators provide reliable coverage of patella and knee defects, bestowing versatility and flexibility to the reconstructive surgeon's armamentarium.

BACKGROUND: The supraclavicular artery island flap is a useful regional option in head and neck reconstruction. Previous studies have recorded pedicle length, caliber, and ink injection studies of the supraclavicular artery. This study presents a three- and four-dimensional appraisal of the vascular anatomy and perfusion of the supraclavicular artery island flap using a novel computed tomographic technique. METHODS: Ten supraclavicular artery island flaps were harvested from fresh cadavers. Each flap was injected with contrast media and subjected to dynamic computed tomographic scanning using a GE Lightspeed 16-slice scanner. Static computed tomographic scanning was also undertaken using a barium-gelatin mixture. Images were viewed using both General Electric and TeraRecon systems, allowing the appreciation of vascular territory (three-dimensional) and analysis of perfusion flow (four-dimensional). RESULTS: The entire skin paddle was perfused in the majority (nine of 10) of flaps. One of the flaps was perfused only 50 percent. In this case, the pedicle artery was found to be much smaller than the other flap pedicles. Direct linking vessels and recurrent flow by means of the subdermal plexus were found to convey the flow of contrast between adjacent perforators. This explains how perfusion extends to adjacent perforators by means of interperforator flow, and how perfusion is maintained all the way to the distal periphery of the flap. CONCLUSIONS: Using this imaging technique, the authors elucidated the vascular anatomy of the supraclavicular artery island flap. This study confirms previous clinical findings that the supraclavicular artery island flap is a reliable option and gives surgeons new information for future flap refinement.

BACKGROUND: Bottoming out is a well-known phenomenon described with reduction mammaplasty (RM). To date, the evaluation of post-operative bottoming out remains an imprecise science. The following study reports the application of three-dimensional (3D) photography to objectively investigate changes in breast morphology. METHODS: Patients undergoing medial pedicle RM had 3D photographs (Konica Minolta V910) taken during the early and late post-operative period (early=60-120 days; late=400-500 days). 3D images were compared and bottoming out was assessed with 3D parameters and vectors including total breast volume, volumetric tissue distribution above and below the Central (C) plane, distance of the C-plane to the lowest point of the breast, and maximum anterior-posterior projection from the chest wall. RESULTS: Post-operative images from 15 consecutive RM patients showed an average volume of 556+/-144cm3 (early) and 441+/-183cm3 (late). The percent of tissue in the upper pole of the breast changed from the early to late post-operative period (76% vs. 69%, respectively; p<0.01). The distance from a fixed C-plane to the inferior pole significantly increased (42+/-15mm early vs. 51+/-18mm late; p<0.01). AP projection decreased by an average of 6.23mm (p<0.01). The lateral border of the IMF significantly dropped by 6.27mm. CONCLUSIONS: This study objectively describes both the occurrence of bottoming out and the quantitative amount in terms of changes in volumetric distribution, surface topography and breast projection. With 3D photography, plastic surgeons can perform objective evaluation of breast transformation over time, which ultimately will aid in planning to allow for better surgical outcomes

BACKGROUND AND OBJECTIVE: In the field of bone implant surfaces, the effects of nanoscale modifications have received significant attention. In the present study, bone cell activity on 2 implant surfaces with similar microtopography but distinct chemistry and nanotopography (sandblasted/acid-etched surface as control group, and calcium phosphate (CaP) low impregnated surface (Ossean) as test group, both from Intra-Lock, Boca Raton, FL) were evaluated. STUDY DESIGN: The 2 surfaces were characterized by X-ray photoelectronic spectroscopy (XPS) and scanning electron microscopy (SEM) up to x200,000 magnification. The micrometer level roughness profiles were evaluated by means of computer software. Cell adhesion, proliferation, and alkaline phosphatase activity were assessed with human SaOS-2 osteoblasts and bone mesenchymal stem cells in nonosteogenic culture conditions. RESULTS: The XPS and SEM results showed that the Ossean surface presented low levels of CaP impregnation within the titanium oxide layer and texturization at the nanometer scale (nanoroughness) compared with the control surface. Moreover Ossean surface induced significantly higher cell differentiation levels than the control (P < .01). CONCLUSION: This study showed that both homogeneous nanoroughness and CaP low impregnation differently affected in vitro bone cell behavior compared with the control moderately rough surface with less texturing in the nanometer scale. However, the relative importance of nanotopography and surface chemistry in cell reactions is yet to be determined.

BACKGROUND: Surgical planning aims to restore coordinated eyelid function. Although achieving voluntary eye closure is one of the primary goals, it cannot guarantee return of involuntary blink. Restoration of the afferent pathway of the reflex is a prerequisite, but successful coordination of the reflex components and restoration of their time-related function are also required. METHODS: A retrospective review of 49 patients who underwent dynamic procedures for blink restoration was performed. The patients were divided into two groups. Group A (n = 42) included patients who underwent nerve transfers: cross-facial nerve grafting and subsequent microcoaptations, mini-hypoglossal nerve transfers, and direct orbicularis oculi neurotization. Group B (n = 14) included patients who underwent eye sphincter substitution techniques: pedicled frontalis, free platysma, mini-temporalis, and a slip of free pectoralis minor transfers. Seven of the patients included in the groups underwent both nerve and muscle transfer procedures. Objective blink ratios were measured according to an established protocol by the senior author (J.K.T.). RESULTS: Thirty patients were girls and 19 were boys. The age of the patients ranged from 1 to 17 years, with a mean +/- SD age of 7.5 +/- 3.2 years. Denervation time ranged from 76 months to 15.25 years. Blink improvement was noted in all of the patients. Blink scores and ratios were consistently better in group A than in group B. CONCLUSION: Dynamic procedures provide the functional potential on which subsequent static procedures can be performed to aid blink return, taking into account the future needs of the still growing patient

Plastic surgery is a broad-based discipline with emphasis on areas such as breast, craniomaxillofacial, burn, aesthetic, and hand surgery as well as complex wounds and wound healing. Plastic surgery as a specialty captures a great deal of media attention over many other fields of medicine, so education, training, and credentialing have become an area of national interest. The purpose of this article was to provide information on the organization, basic requirements for training, fellowship, and volunteer opportunities within the specialty

It was previously shown that CEACAM1 on melanoma cells strongly predicts poor outcome. Here, we show a statistically significant increase of serum CEACAM1 in 64 active melanoma patients, as compared to 48 patients with no evidence of disease and 37 healthy donors. Among active patients, higher serum CEACAM1 correlated with LDH values and with decreased survival. Multivariate analysis with neutralization of LDH showed that increased serum CEACAM1 carries a hazard ratio of 2.40. In vitro, soluble CEACAM1 was derived from CEACAM1(+), but neither from CEACAM1(-) melanoma cells nor from CEACAM1(+) lymphocytes, and directly correlated with the number of CEACAM1(+) melanoma cells. Production of soluble CEACAM1 depended on intact de novo protein synthesis and secretion machineries, but not on metalloproteinase function. An unusually high percentage of CEACAM1(+) circulating NK and T lymphocytes was demonstrated in melanoma patients. CEACAM1 inhibited killing activity in functional assays. CEACAM1 expression could not be induced on lymphocytes by serum from patients with high CEACAM1 expression. Further, expression of other NK receptors was impaired, which collectively indicate on a general abnormality. In conclusion, the systemic dysregulation of CEACAM1 in melanoma patients further denotes the role of CEACAM1 in melanoma and may provide a basis for new tumor monitoring and prognostic platforms.

PURPOSE: Cancer stem cells are found in many tumor types and are believed to lead to regrowth of tumor mass due to their chemoresistance and self-renewal capacity. We previously demonstrated small subpopulations of cells in retinoblastoma tissue and cell lines that display cancer stem cell-like activities, including expression of stem cell markers, Hoechst dye exclusion, slow cycling, and self-renewal ability. Identifying factors regulating stem cell proliferation will be important for selectively targeting stem cells and controlling tumor growth. Wingless and Int1 (Wnt) signaling is an essential cellular communication pathway that regulates proliferation and differentiation of non-neoplastic stem/progenitor cells in the retina and other tissues, but its role in cancer stem cells in the retinal tumor retinoblastoma is unknown. In this study, we investigated whether the Wnt pathway activator lithium chloride (LiCl) regulates proliferation of retinoblastoma cancer stem-like cells. METHODS: The number of stem-like cells in Weri and Y79 retinoblastoma cell line cultures was measured by 5-bromo-2-deoxyuridine (BrdU) pulse-chase, immunohistochemistry, and quantitative polymerase chain reaction (PCR) for stem cell marker genes. The cell lines were sorted into stem-like and non-stem-like populations by fluorescence-activated cell sorting (FACS), using an antibody against the stem cell marker ATP-binding cassette, subfamily G, member 2 (ABCG2). Activated Wnt signaling was measured in the sorted cells by western blotting and immunolocalization of the central mediator beta-catenin. RESULTS: LiCl increased the number of stem-like cells, measured by BrdU retention and elevated expression of the stem cell marker genes Nanog, octamer transcription factor 3 and 4 (Oct3/4), Musashi 1 (Msi1), and ABCG2. Sorted ABCG2-positive stem-like cells had higher levels of beta-catenin than ABCG2-negative non-stem cells, suggesting elevated canonical Wnt signaling. Furthermore, stem cell marker gene expression increased after small interfering RNA (siRNA) knock-down of the Wnt inhibitor secreted frizzled-related protein 2 (SFRP2). CONCLUSIONS: These results indicate that the cancer stem-like cell population in retinoblastoma is regulated by canonical Wnt/beta-catenin signaling, which identifies the Wnt pathway as a potential mechanism for the control of stem cell renewal and tumor formation in retinoblastoma tumors in vivo.