Biomedical subjects

David W Low

Publications and source records attributed to David W Low.

14 recordsLinked to original sources

PubMed2006

Total face reconstruction using a pre-expanded, bilateral, extended, parascapular free flap.

A 37-year-old male sustained extensive, self-inflicted gasoline burns to his head, face, chest, upper extremities, and anterior thighs. Although he underwent initial resuscitation and skin grafting at a regional burn center, he presented to our clinic with thick, unstable burn scars covering his face and scalp. He had multiple functional and esthetic needs that are described. He required approximately 30 x 35 cm of skin to resurface his entire face and anterior scalp. His back and buttocks were his only unscarred, potential donor sites. Authors have described use of a bilateral parascapular free flap for similar deformities. This patient required pre-expansion of this free flap to maximize available tissue and minimize the donor defect. This technique provided this patient with a large area of healthy skin and soft tissue that will ultimately provide this patient with an improved functional and esthetic result.

Adult↗

PubMed2005

Uniform scale-independent gene transfer to striated muscle after transvenular extravasation of vector.

BACKGROUND: The muscular dystrophies exemplify a class of systemic disorders for which widespread protein replacement in situ is essential for treatment of the underlying genetic disorder. Somatic gene therapy will require efficient, scale-independent transport of DNA-containing macromolecular complexes too large to cross the continuous endothelia under physiological conditions. Previous studies in large-animal models have revealed a trade-off between the efficiency of gene transfer and the inherent safety of the required surgical and pharmacological interventions to achieve this. METHODS AND RESULTS: Rats and dogs underwent limb or hemibody isolation via atraumatic tourniquet placement or myocardial isolation via heterotopic transplantation. Recombinant adenovirus (10(13) particles per kilogram) or recombinant adeno-associated virus (10(14) genome copies/kg) encoding the lacZ transgene was delivered through pressurized venous infusion without pharmacological mediators. Muscle exhibited almost 100% myofiber transduction in rats and dogs by X-galactosidase staining and significantly higher beta-galactosidase levels compared with nonpressurized delivery. No significant difference was seen in beta-galactosidase levels between 100- or 400-mm Hg groups. The <50-mm Hg group yielded inhomogeneous and significantly lower transgene expression. CONCLUSIONS: Uniform scale- and vector-independent skeletal and cardiac myofiber transduction is facilitated by pressurized venous infusion in anatomic domains isolated from the central circulation without pharmacological interference with cardiovascular homeostasis. We provide the first demonstration of uniform gene transfer to muscle fibers of an entire extremity in the dog, providing a firm foundation for further translational studies of efficacy in canine models for human diseases.

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↗

PubMed2004

Myosin gene mutation correlates with anatomical changes in the human lineage.

Powerful masticatory muscles are found in most primates, including chimpanzees and gorillas, and were part of a prominent adaptation of Australopithecus and Paranthropus, extinct genera of the family Hominidae. In contrast, masticatory muscles are considerably smaller in both modern and fossil members of Homo. The evolving hominid masticatory apparatus--traceable to a Late Miocene, chimpanzee-like morphology--shifted towards a pattern of gracilization nearly simultaneously with accelerated encephalization in early Homo. Here, we show that the gene encoding the predominant myosin heavy chain (MYH) expressed in these muscles was inactivated by a frameshifting mutation after the lineages leading to humans and chimpanzees diverged. Loss of this protein isoform is associated with marked size reductions in individual muscle fibres and entire masticatory muscles. Using the coding sequence for the myosin rod domains as a molecular clock, we estimate that this mutation appeared approximately 2.4 million years ago, predating the appearance of modern human body size and emigration of Homo from Africa. This represents the first proteomic distinction between humans and chimpanzees that can be correlated with a traceable anatomic imprint in the fossil record.

Amino Acid Sequence↗

PubMed2004

The Children's Hospital of Philadelphia modification of the Furlow double-opposing z-palatoplasty: long-term speech and growth results.

Of the 261 nonsyndromic patients we studied, over 90% had minimal or absent hypernasality, almost 86% had inconsistent or no nasal emission, and 95% had no articulation errors related to velar function. The patients with a Pittsburgh score indicating an incompetent velopharyngeal mechanism comprised only about 6% of the group. Ninety-four percent had a socially functional speech quality. Secondary surgery was done in 6.5% of patients and was done or was recommended in about 8% of patients. Patients with isolated cleft palate seemed to do less well, although their outcomes were not statistically different from those with complete unilateral and bilateral clefts. Relaxing incisions have kept our fistula rate to an acceptably low rate of 6.8%. No major soft palate dehiscences or hard palate flap losses have occurred. The speech outcomes we are achieving are improved over our historical results and compared with published reports using nondouble reversing z-palatoplasty techniques. Similar outcomes with the Furlow repair have been confirmed. Maxillary growth, occlusion, and the need for orthognathic surgery do not seem to be influenced by the CHOP modification of the Furlow double-opposing z-palatoplasty. These modifications facilitate a tension free-closure and a low fistula rate.

Child, Preschool↗

PubMed2004

Mental health histories and psychiatric medication usage among persons who sought cosmetic Surgery.

This retrospective chart review study examined the mental health histories and psychiatric medication usage of persons who sought cosmetic surgery. The medical records of 232 patients who had undergone a consultation for a cosmetic procedure were reviewed. The rates of self-reported psychiatric disorders and of psychiatric medication usage of these patients were compared with those of 200 patients who underwent noncosmetic procedures. Nineteen percent of cosmetic surgery patients reported a mental health history, significantly greater than the 4 percent of the noncosmetic patients who reported a psychiatric history. Eighteen percent of the cosmetic patients reported using a psychiatric medication at the time of their consultation, also significantly greater than the 5 percent of the noncosmetic patients who reported psychiatric medication usage. These results underscore the importance of collecting a psychiatric history from prospective cosmetic surgery patients. Recommendations for assessing patients' psychiatric history and status are provided.

Adult↗

PubMed2003

Extended left colon interposition for esophageal replacement using arterial augmentation.

Gastric necrosis after esophagectomy is a difficult clinical problem. Remedial operations to reestablish gut continuity usually rely on the use of the left colon as the neo-esophagus. Previous resection of the necrotic stomach, adhesions associated with a multiple redo-laparotomy and the need to use a substernal route to reach the cervical esophagus all conspire to produce a requirement for increased conduit length. We present a case in which the "arterial supercharge technique" was used to provide a colonic interposition with extended length in such a clinical situation.

Anastomosis, Surgical↗

PubMed2003

Management of adult facial vascular anomalies.

Vascular anomalies are best classified by biologic behavior-active hemangiomas, and inactive vascular malformations. Hemangioma growth is restricted to infancy, but residual deformity may persist to adult life in the form of redundant skin, bulky fibrofatty tissue, and ectatic cutaneous vessels. Treatment largely consists of scar revision and laser photocoagulation of residual vascular pigmentation. Vascular malformations are present throughout life and can cause increasing facial distortion and disfigurement as capillaries, veins, lymphatics, and/or arteries further dilate and the facial features hypertrophy. A variety of treatment options include laser photocoagulation, sclerotherapy, embolization, and direct surgical excision, and often a combination of techniques yields improved results. In many cases, however, therapy is only palliative, and patients should be advised of the limitations of each treatment option to avoid unrealistic expectations and disappointing results.

Adult↗

PubMed2003

Body image concerns of breast augmentation patients.

This study investigated the body image concerns of women who sought cosmetic breast augmentation. Thirty breast augmentation candidates completed several measures of body image before their initial surgical consultation. Thirty physically similar women who were not interested in breast augmentation were recruited from the medical center and university community and also completed the measures. Breast augmentation candidates, as compared with women not seeking augmentation, reported greater dissatisfaction with their breasts. Augmentation candidates rated their ideal breast size, as well as the breast size preferred by women, as significantly larger than did controls. In addition, women interested in breast augmentation reported greater investment in their appearance, greater distress about their appearance in a variety of situations, and more frequent teasing about their appearance. Finally, breast augmentation candidates also reported more frequent use of psychotherapy in the year before the operation as compared with women not seeking augmentation. These results replicate and extend previous studies of body image in cosmetic surgery patients.

Adult↗

PubMed2003

The use of a subfascial vicryl mesh buttress to aid in the closure of massive ventral hernias following damage-control laparotomy.

Damage control laparotomy for life-threatening abdominal conditions has gained wide acceptance in the management of exsanguinating trauma patients as well as septic patients with acute abdomen. Survivors considered too ill to undergo definitive abdominal wall closure are temporized, often with skin grafting on granulated viscera. These maneuvers compromise the integrity of the anterior abdominal wall and result in a subset of patients with loss of abdominal domain and massive, debilitating ventral hernias. A retrospective review was conducted of 21 such patients (16 men, five women) who underwent elective abdominal wall reconstruction at the Hospital of the University of Pennsylvania between November of 1998 and October of 2000. The purpose of this study was to report the authors' experience with these complex abdominal wall reconstructions. A double-layer, subfascial Vicryl mesh buttress was used in all repairs to aid in reestablishing abdominal wall integrity. The mean hernia size was 813 cm2 (range, 75 to 1836 cm2), and the average interval to definitive repair was 24.4 months (range, 3 weeks to 11 years). Mean follow-up was 13.5 months (range, 1 month to 40 months). Twenty patients (95 percent) had successful ventral hernia repair. Four patients with massive hernias (924 to 1836 cm2) required submuscular Marlex mesh implantation. Two patients (10 percent) developed abdominal compartment syndrome that required surgical decompression. One patient (5 percent) developed an incisional hernia at a prior colostomy site. Four patients (19 percent) had superficial skin dehiscence that healed secondarily with daily wound care. There were no mesh infections. In most cases, successful single-stage repair of large ventral hernias following damage control laparotomy can be achieved using a subfascial Vicryl mesh buttress in combination with other established reconstructive techniques. Massive defects exceeding 900 cm2 typically require permanent mesh implantation to achieve fascial closure and to minimize the risk of postoperative abdominal compartment syndrome and recurrent herniation. This technique represents an improved solution to a complicated problem and optimizes the aesthetic and functional outcome for these debilitated patients.

Abdominal Injuries↗

PubMed2003

Surgical airway management in Pierre Robin sequence: is there a role for tongue-lip adhesion?

OBJECTIVE: The purpose of this study was to examine the efficacy of tongue-lip adhesion (TLA) in the management of clinically significant airway obstruction associated with Pierre Robin sequence. DESIGN: The records of all children admitted to The Children's Hospital of Philadelphia with a diagnosis of Pierre Robin sequence were reviewed. Charts were reviewed for birth data, diagnosis, preoperative airway management methods, and surgical intervention. Records of infants undergoing TLA were analyzed for timing of surgery, operative technique, postoperative complications, length of hospital stay, and treatment outcome. RESULTS: Over the 28-year period 1971 to 1999, 107 patients (47 boys, 60 girls) meeting the criteria for Pierre Robin sequence were admitted for treatment. Of these, 74 (69.2%) were successfully managed by positioning alone. Surgical management of the airway was performed in the remaining 33 (30.8%) patients, 29 of whom underwent TLA and 4 of whom underwent tracheostomy. Dehiscence of the adhesion occurred in five patients (17.2%), two of whom subsequently required tracheostomy. Within the group of patients who underwent mucosal adhesion alone, the dehiscence rate was 41.6%. When the adhesion included muscular sutures, however, dehiscence was not observed in any patient. Of the 24 patients in whom primary TLA healed uneventfully, airway obstruction was successfully relieved in 20 (83.3%). Failure of a healed TLA to relieve the airway obstruction resulted in conversion to a tracheostomy in four patients. Six patients who underwent TLA (20.7%) ultimately required a tracheostomy; five of these patients (83.3%) were syndromic. Of patients requiring preoperative intubation, 42.9% ultimately required tracheostomy. CONCLUSION: TLA successfully relieves airway obstruction that is unresponsive to positioning alone in the majority of patients with Pierre Robin sequence and should therefore play an important role in the management of these infants.

Age Factors↗

PubMed2002

Surgical reconstruction of pediatric pressure sores: long-term outcome.

The long-term outcome after the surgical repair of pressure sores in the adult population has been well studied. Recurrence rates from 25 to 80 percent have been reported, despite improvements in surgical repair and mechanical support devices. Such high recurrence rates have led many investigators to question the rationale for the surgical closure of pressure sores. There are no published long-term data that document pressure sore recurrence after surgical treatment in the pediatric population. A retrospective analysis of all patients who underwent surgical reconstruction of grade III and IV pressure sores at the Children's Hospital of Philadelphia from 1987 to 1999 was performed. During this 12-year period, 19 consecutive patients with a mean age of 16.2 years were operated on for 25 pressure sores. Follow-up was obtained for 15 patients (79 percent), who underwent repair for 20 pressure sores. Mean postoperative follow-up was 5.3 years (range, 11 months to 11 years). Mean age at the time of surgery was 16.5 years. The overall pressure sore recurrence rate was 5 percent (1 of 20 sores). Overall patient recurrence (previous patient who developed a new sore) was 20 percent (3 of 15 patients). In contrast to the recurrence rates reported for the surgical repair of pressure sores in the adult population, the recurrence rate of 5 percent in the pediatric population is significantly lower. This demonstrates that the surgical reconstruction of pressure sores in the pediatric patient can be successful and provide long-term skin integrity.

Adolescent↗

PubMedDate not supplied

Pediatric osteoblastoma of the sternum: a new surgical technique for reconstruction after removal: case report and review of the literature.

Benign osteoblastoma is a rare tumor of bone that has been reported in a variety of skeletal locations. A case of an isolated benign osteoblastoma in the sternum of an 11-year-old boy is described. In the chest wall, osteoblastoma has been reported in the ribs, and rarely in the sternum. To the authors' knowledge, this is the first report of an isolated sternal osteoblastoma in a child presented in the literature. The clinical and radiologic presentation of osteoblastoma is discussed, as well as an approach for reconstruction of the sternal defect following removal of the tumor. Experience with sternal reconstruction in the pediatric population is limited. This case demonstrates that osteoblastoma of the sternum can be successfully treated with wide resection and that sternal defect reconstruction can be accomplished successfully in a child.

Biocompatible Materials↗