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Biomedical subjects

James M Smartt

Publications and source records attributed to James M Smartt.

8 recordsLinked to original sources
PubMed2006

Nipple reduction using the modified top hat flap.

BACKGROUND: Large nipples, disproportionate to the small areola and breast size, are an ethnic characteristic frequently encountered among Asian female patients. Patients seek correction to improve cosmesis and alleviate psychological and physical discomfort. The authors present a new technique of nipple reduction and describe its potential advantages over other techniques. METHODS: Between March of 2003 and April of 2005, 34 nipple reductions were performed in 19 female patients (mean age, 40.5 +/- 5.6 years) using the modified top hat flap. The neonipple is designed to reduce the nipple diameter at the superior pole of the nipple while preserving the subdermal plexus. A crescent-shaped section of nipple skin below the proposed neonipple is excised, maintaining the integrity of the neonipple and the central nipple core. Two lateral wing flaps are elevated and trimmed to reduce both nipple height and diameter at the lateral walls of the nipple. The flaps of the neonipple are then sutured to the areola. RESULTS: Postoperative recovery was rapid and uneventful and no complications were encountered. The mean diameter of the hypertrophic nipple was 16.3 +/- 2.6 mm (range, 16 to 30 mm). The mean diameter of the neonipple was 7.9 +/- 1.7 mm (range, 5 to 11 mm), with an average reduction of 8.4 +/- 1.6 mm (range, 5 to 20 mm). At 17.2 +/- 2.9 months of follow-up, the neonipple had a natural appearance, with less projection and an inconspicuous scar. There was no statistically significant difference on monofilament sensation testing (p = 0.5829) between reduction nipple and areola in 11 nipples of seven patients. CONCLUSIONS: The modified top hat flap requires minimal preoperative planning, is easy to perform, and yields reproducible results. This technique decreases both the diameter and height of any size nipple and can be modified to meet patient preferences. Because the continuity of the neonipple with the subdermal arterial plexus is maintained and the majority of the parenchymal elements are preserved, nipple sensation and circulation remain largely unaffected.

Adult↗
PubMed2005

Repair of the immature and mature craniofacial skeleton with a carbonated calcium phosphate cement: assessment of biocompatibility, osteoconductivity, and remodeling capacity.

BACKGROUND: The apatite compounds used most commonly in craniofacial reconstruction are highly crystalline and biologically inert ceramics. Because their capacity to be replaced by native bone is limited, they have found little application in repair of the growing craniofacial skeleton. Carbonated calcium phosphate cements more closely resemble the mineral phase of bone, thereby offering enhanced bioresorption and osteoconductivity, but their fate in the immature and mature craniofacial skeleton has not been investigated. METHODS: The authors hypothesized that the capacity for cell-mediated remodeling of carbonated calcium phosphate cements is based on (1) their crystallographic and compositional similarity to the mineral phase of bone and (2) the osteogenic capacity of the host. Four noncritical-sized calvarial defects were created in six 3-week-old and six 16-week-old Yorkshire pigs. The defects were repaired with autologous bone, sintered carbonated calcium phosphate cement disks with a higher crystal order, or carbonated calcium phosphate cement (Norian CRS; Synthes Maxillofacial, West Chester, Pa.). The fourth defect was left empty as a control. Specimens were harvested at 30 and 90 days postoperatively. RESULTS: Empty defects healed with dense fibroconnective tissue in all groups. Autologous bone grafts underwent complete remodeling and replacement with woven bone at both time points. Sintered carbonated calcium phosphate disks demonstrated no bony ingrowth or remodeling. In immature animals, carbonated calcium phosphate cement implants were progressively replaced with woven bone through osteoclast-mediated resorption and osteoblast-mediated bone formation. Only minimal remodeling of the carbonated calcium phosphate cement implants was observed in skeletally mature animals. CONCLUSIONS: The results of these experiments suggest that the extent of remodeling of carbonated calcium phosphate cement is dependent on both the composition of the implant itself and the osteogenic capacity of the host and that carbonated calcium phosphate cement may be used successfully for inlay applications in the immature craniofacial skeleton.

Animals↗
PubMed2005

The pediatric mandible: I. A primer on growth and development.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Describe embryonic and fetal mandibular development. 2. Summarize the aggregate changes in mandibular form from birth to puberty. 3. Describe the eruption and maturation of the deciduous and permanent mandibular dentition. BACKGROUND: In this, the first of two articles addressing the surgical management of pediatric mandibular fractures, the authors provide a detailed discussion of mandibular development and anatomy during the fetal period, infancy, and childhood. METHODS: A review of the pertinent literature was performed. The changing structure of the developing mandible is discussed, with particular attention to surgically relevant anatomical structures. RESULTS: Throughout development, key anatomical structures with relevance to surgical therapy change markedly in position. The mandible undergoes significant change in its bony structure and the composition of its surrounding soft tissues. The mandible's bony structure becomes more robust, with an increasingly acute gonial angle and enlargement of the ramus and body. Furthermore, the mandible provides the bony structure from which tooth buds erupt as the deciduous and permanent dentition--a process that generates significant growth of the alveolar process. As a consequence, the distance between the developing dentition and the inferior mandibular border increases. While the canal of the inferior alveolar nerve undergoes significant superior displacement, the mental foramen becomes positioned more posteriorly over time. In addition, the ligamentous and muscular attachments that surround the temporomandibular joint become increasingly robust. Throughout childhood and adolescence, the blood supply of the mandibular body changes little, with the buccal periosteal plexus and inferior dental artery making significant contributions. CONCLUSIONS: Mandibular growth provides the basis for normal occlusal relations and the generation of increasingly large masticatory force. Although the exact mechanisms of bone remodeling during mandibular development remain unclear, the process likely receives contributions from primary growth centers and the response to local alterations in biomechanical force produced by surrounding soft-tissue structures. A working knowledge of the changing mandibular anatomy is a prerequisite for effective clinical management of traumatic injury.

Bone Remodeling↗
PubMed2005

The pediatric mandible: II. Management of traumatic injury or fracture.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Describe the changing epidemiology of mandibular fractures in children and adolescents. 2. Discuss the appropriate use of internal fixation in the treatment of pediatric mandibular fractures. 3. Describe the difficulties posed by the deciduous dentition in the use of interdental wiring. 4. Understand reasons why techniques specific to adult fractures may not be applicable to the growing mandible. 5. Understand the etiology and epidemiology of pediatric mandibular fractures. 6. Understand the reasons for conservative (closed) versus aggressive (open) treatment of mandibular injury. BACKGROUND: Fractures of the pediatric mandible are complicated by the anatomic complexity of the developing mandible, particularly by the presence of tooth buds and the eruption of deciduous and permanent teeth. Traditional methods of fracture reduction and fixation employed in adults have little applicability in the pediatric population. METHODS: The authors describe the surgical techniques that have been used at their institution and those that can be used safely in the pediatric setting. RESULTS: In most cases, "conservative" management is the preferred option, especially in the treatment of condylar fractures. In cases requiring surgical intervention, interdental wiring, drop wires in combination with circummandibular wires, and acrylic splints are suited well to specific phases of dental maturation. CONCLUSION: Open reduction and internal fixation using monocortical screws and microplates or resorbable plates and screws are acceptable techniques in the pediatric patient, but they require special safeguards. Algorithms are presented to simplify management of these complicated injuries.

Adolescent↗
PubMed2005

Intrauterine fetal constraint induces chondrocyte apoptosis and premature ossification of the cranial base.

BACKGROUND: The spheno-occipital synchondrosis is an important growth center of the craniofacial skeleton and a primary site of malformation in syndromic forms of craniosynostosis. Clinical and laboratory investigations have demonstrated that premature closure of cranial vault sutures in nonsyndromic craniosynostosis is associated with characteristic alterations in cranial base morphology. However, a causal link between premature fusion of calvarial sutures and changes in the cranial base remains elusive. The purpose of these experiments was to test the hypothesis that intrauterine head constraint produces ultrastructural changes in the spheno-occipital synchondroses of fetal mice. METHODS: Fetal constraint was induced through uterine cerclage of six pregnant C57Bl/6 mice on the eighteenth day of gestation. Fetuses were harvested after growing to 24, 48, and 72 hours beyond the normal 20-day gestational period. Between six and nine fetuses were harvested at all time points in both treatment and control groups. The morphology and cell biology of the spheno-occipital synchondroses, in constrained fetuses and unconstrained controls, were examined using hematoxylin and eosin-stained sections. Chondrocyte apoptosis was examined using terminal deoxynucleotidyl transferase-mediated dUDP end-labeling assays and electron microscopy. RESULTS: In nonconstrained animals, the spheno-occipital synchondrosis demonstrated normal architecture and normal chondrocyte morphology at all time points. In contrast, intrauterine constraint resulted in a progressive disruption of the normal cellular architecture of the spheno-occipital synchondrosis over 72 hours, with premature ossification of the synchondrosis. Widespread chondrocyte apoptosis within the synchondrosial growth center was demonstrated by terminal deoxynucleotidyl transferase-mediated dUDP end-labeling assays and electron microscopy. CONCLUSION: These experiments confirm the ability of intrauterine constraint to induce changes in the morphology and cell biology of the cranial base in synostotic fetuses.

Animals↗
PubMed2005

Intermittent hydrostatic compression promotes nitric oxide production and osteodifferentiation of fetal dural cells.

PURPOSE: The aim of these studies was to evaluate the biologic response of fetal dural cell cultures to compressive mechanical force. METHODS: Primary cell cultures from the dura mater of E18 CD-1 mice were subjected to 2 PSI of intermittent hydrostatic compression (IHC) at a frequency of 0.5 Hz. Quantitative measures of the expression of Osterix (Osx), osteopontin (OP), endothelial nitric oxide synthase (eNOS) and Noggin were performed by RT-PCR following 3, 6, and 12 hours of exposure to IHC. Nitric oxide production was quantified through the measurement of NO metabolites following 6 hours of exposure to IHC. RESULTS: IHC resulted in an increase in Osx, OP, and eNOS expression compared with controls at all time points. The expression of Noggin decreased at all time points. Exposure to IHC resulted in a significant increase in the production of NO metabolites at 6 hours when compared with controls. CONCLUSIONS: These experiments indicate that dural cell biology is significantly altered following exposure to IHC. Specifically, IHC promotes production of NO and osteodifferentiation in fetal dural cell cultures, with increases in the expression of osteoinductive genes and decreases in inhibitors of osteogenesis.

Animals↗
PubMed2004

Hybrid constructs for craniofacial reconstruction: sustained gene delivery using demineralized bone matrix putty.

These experiments evaluate the efficacy of a demineralized bone matrix putty engineered as a hybrid construct for sustained, site-directed gene transfer using an adenoviral vector. In vitro experiments were performed to evaluate the optimal dosing for gene transfer to fetal calvarial osteoblasts and dural cells and for the sustainability of gene transfer from the hybrid constructs. In the dosing experiments, hybrid constructs were created by combining 0.5 mL of demineralized bone matrix putty (DBX; SYNTHES Maxillofacial, Monument, CO) with 1 x 10(8), 1 x 10(7), or 1 x 10(6) particle-forming units (PFU) of an adenoviral vector carrying the gene encoding green fluorescent protein (AdGFP). These constructs were then placed in direct contact, or in transwell coculture, with fetal murine calvarial osteoblasts or dural cells at a multiplicity of infection (MOI = viral particle/cell ratio) of 1000, 100, and 10. The sustainability of gene transfer was tested through transfer of the hybrid construct to wells containing untransfected cells every 24 hours for 30 days. In both experiments, gene transfer was determined through the visualization of GFP using fluorescence light microscopy 24 hours after the onset of transfection. Optimal dosing for gene transfer occurred at an MOI of 10 for calvarial osteoblasts and 100 for dural cells. At greater concentrations, toxicity was observed in the majority of samples. Gene transfer to fetal dural cells and calvarial osteoblasts was sustained throughout the 30-day period. These experiments suggest that adenoviral vectors could be successfully incorporated within demineralized bone matrix to provide effective, sustained, site-directed gene transfer.

Adenoviridae↗