Skin sensitivity of adults on the Isthmus of Panama to Mycobacterium xenopi sensitin.

A group of 106 adult Panamanian men were skin tested with a standard human tuberculin (RT 23) and three sensitins prepared from atypical mycobacteria. Two of the sensitins (prepared from Mycobacterium kansasii and Battey organism) are commonly used to detect atypical mycobacterial infections. The third (prepared from M. xenopi) had not been used in Panama previously. Skin sensitivity proved to be significantly higher to the M. xenopi sensitin than to the others. The known epidemiology of M. xenopi is briefly reviewed.

An epidemic of histoplasmosis on the Isthmus of Panama.

Forty-seven men on the Isthmus of Panama were exposed to histoplasmosis in an old bunker inhabited by bats. The resulting epidemic was studied with serial clinical, serological, and radiological examinations. Thirty-seven (78.7%) of the men showed serological evidence of infection and 26 (70.3%) had symptoms. Incubation periods ranged from 4 to 30 days. A general relationship between severity of illness and degree of exposure was noted. The agar gel diffusion test for precipitin antibodies was more sensitive than the complement-fixation test or slide test in detecting infection with Histoplasma capsulatum. Decontamination procedures and environmental studies are described.

Effect of epinephrine on local cutaneous blood flow.

Quantification of the effect of subcutaneous infiltration of saline with epinephrine and of lidocaine with epinephrine on local cutaneous blood flow was accomplished utilizing the laser Doppler method. A comparison of the onset of vasoconstriction, magnitude of diminished blood flow, and duration of effect was made for several commonly used concentrations of epinephrine. Injected solutions containing epinephrine in concentrations of 1:200,000 and higher offered good vasoconstrictor effects when both the magnitude and duration of flow reduction were considered. There was a significant (P = 0.0001) difference in flow between epinephrine concentrations of 1:400,000 and all others. There were no significant differences (P greater than 0.05) between concentrations of 1:200,000 and 1:100,000 or 1:100,000 and 1:50,000.

The tracheoesophageal diversion and laryngotracheal separation procedures for treatment of intractable aspiration.

Intractable aspiration is a severe and often fatal complication in patients with impaired protective function of the larynx. This problem is usually a result of central nervous system disorders such as cerebrovascular accident, trauma, neoplasms, or degenerative disease. Surgical separation of the upper respiratory tract from the digestive tract can prevent recurrent contamination of the respiratory system in these patients. Two such procedures are the tracheoesophageal diversion procedure and a modification of this operation, the laryngotracheal separation procedure. The Virginia Mason Medical Center experience with these procedures, their indications, technique, and outcome are presented. In addition, cases of successful surgical reversal of the diversion procedures are discussed.

A finite element model of skin deformation. I. Biomechanics of skin and soft tissue: a review.

Skin flap design has traditionally been based on geometric models which ignore the elastic properties of skin and its subcutaneous attachments. This study reviews the theoretical and experimental mechanics of skin and soft tissues (I) and proposes a mathematical model of skin deformation based on the finite element method (III). Finite element technique facilitates the modeling of complex structures by analyzing them as an aggregate of smaller elements. This paper gives the results of an animal model developed to study the deformation and mechanical properties of skin, including its viscoelastic properties (hysteresis, creep, and stress relaxation). A new skin extensometer, constructed with digital stepper motors and controlled with a microcomputer, is described to measure these properties for both skin and its subcutaneous attachments. Deformation grids quantitated from photographs with a digitalizing tablet are presented, and computer software is introduced to standardize and analyze them (II). The mathematical model is used to simulate wound closures such as the ellipse and rectangular advancement flap. In addition, a series of mathematical experiments performed to simulate deformation of a strip of skin are described; the relationships between the various elastic constants are investigated; and a comparison of these simulations with actual deformation is presented. Limitations of the model and areas for future investigation are discussed (III).

Expanded polytetrafluoroethylene augmentation of the lower face.

Most options for rejuvenation of the lower face use soft-tissue fillers that augment the appropriate sites. Each of these options has associated risks and benefits. The U.S. Food and Drug Administration recently approved the use of expanded polytetrafluoroethylene (E-PTFE) as a soft-tissue filler in the face. From January 1991 through December 1993, the authors used E-PTFE soft-tissue patches for lower facial augmentation in 41 patients at 115 implant sites. Postsurgical follow-up has ranged from 2.5 to 4.5 years; during this time, complications have occurred in 4 patients. One implant had to be removed because of a seroma (1 patient), 4 implants required further secondary augmentation (2 patients), and 1 implant required revision because of malposition (1 patient). There have been no cases of implant infection, extrusion, long-term inflammation, or capsule formation. In this article, the authors review the technical aspects of E-PTFE use and discuss issues relating to the long-term efficacy of this new option for soft-tissue augmentation. The technique is also compared with other options for rejuvenation of the lower face.

The biomechanics of advancement and rotation flaps.

An animal model (using piglets) has been developed to study the mechanical properties of simple advancement and rotation flaps. The effects of different length-width ratios and defect sizes on the tension required to close a rectangular advancement flap are described. Characteristic curves of force vs. advancement distance are presented and mechanisms discussed. The flaps should have a length-width ratio of a least 1:1; the mechanical advantage of lengthening the flap further is directly related to the measured closing tension. The distribution of tension in a standard 180 degrees rotation flap is analyzed. Maximum tension is found between 90 degrees and 135 degrees (opposite the site of defect closure); this is at variance with the vector commonly pictured. The force required to close a defect with rotation flaps of varying length (45 degree to 180 degrees) is measured. There is little mechanical benefit in extending the flap past 90 degrees.

A finite element model of skin deformation. II. An experimental model of skin deformation.

Skin flap design has traditionally been based on geometric models which ignore the elastic properties of skin and its subcutaneous attachments. This study reviews the theoretical and experimental mechanics of skin and soft tissues (I) and proposes a mathematical model of skin deformation based on the finite element method (III). Finite element technique facilitates the modeling of complex structures by analyzing them as an aggregate of smaller elements. This paper gives the results of an animal model developed to study the deformation and mechanical properties of skin, including its viscoelastic properties (hysteresis, creep, and stress relaxation). A new skin extensometer, constructed with digital stepper motors and controlled with a microcomputer, is described to measure these properties for both skin and its subcutaneous attachments. Deformation grids quantitated from photographs with a digitalizing tablet are presented, and computer software is introduced to standardize and analyze them (II). The mathematical model is used to simulate wound closures such as the ellipse and rectangular advancement flap. In addition, a series of mathematical experiments performed to simulate deformation of a strip of skin are described; the relationships between the various elastic constants are investigated; and a comparison of these simulations with actual deformation is presented. Limitations of the model and areas for future investigation are discussed (III).

A finite element model of skin deformation. III. The finite element model.

Skin flap design has traditionally been based on geometric models which ignore the elastic properties of skin and its subcutaneous attachments. This study reviews the theoretical and experimental mechanics of skin and soft tissues (I) and proposes a mathematical model of skin deformation based on the finite element method (III). Finite element technique facilitates the modeling of complex structures by analyzing them as an aggregate of smaller elements. This paper gives the results of an animal model developed to study the deformation and mechanical properties of skin, including its viscoelastic properties (hysteresis, creep, and stress relaxation). A new skin extensometer, constructed with digital stepper motors and controlled with a microcomputer, is described to measure these properties for both skin and its subcutaneous attachments. Deformation grids quantitated from photographs with a digitalizing tablet are presented, and computer software is introduced to standardize and analyze them (II). The mathematical model used to simulate wound closures such as the ellipse and rectangular advancement flap. In addition, a series of mathematical experiments performed to simulate deformation of a strip of skin are described; the relationships between the various elastic constants are investigated; and a comparison of these simulations with actual deformation is presented. Limitations of the model and areas for future investigation are discussed (III).

Frontal sinus fractures--their suppurative complications and surgical management.

A series of 54 patients treated for frontal sinus fractures at Charity Hospital, New Orleans, from 1967-77 is presented. There were a large number of suppurative complications related to the various medical and surgical managements. Initial treatments included: observation (15), exploration and open reduction (22), obliteration (16), and ablation (1). Four patients with open fractures were not explored and developed recurrent frontal sinusitis; one progressed to an osteomyelitis. Two with posterior table fractures were not explored and developed meningitis (one was then obliterated and developed an epidural abscess). Three patients developed frontal sinus abscesses after obliterations for anterior wall fractures. Fat gave fewer complications than the other commonly used materials. Exploration is advocated for most frontal sinus fractures. Obliteration should be avoided when possible. Fat is the material of choice when obliteration is required.

Isolated nasalis muscle reconstruction in secondary unilateral cleft lip nasal reconstruction.

OBJECTIVES/HYPOTHESIS: Reconstruction of the nasalis muscle in the unilateral cleft lip nasal deformity improves surgical results. STUDY DESIGN: A retrospective analysis of a series of 112 consecutive procedures. METHODS: Chart review and analysis of standardized preoperative and postoperative clinical photographs. RESULTS: Patients treated with this technique had improved contour of the alar base compared with historical controls. CONCLUSION: Nasalis muscle reconstruction should be considered in the repair of the moderate to severe unilateral cleft nose deformity.

Surgical therapy of the eyelids in patients with facial paralysis.

Patients with facial paralysis have a degree of lagophthalmos and paralytic ectropion. We present our experience in the surgical management of 25 consecutive patients treated for these problems. Paralytic lagophthalmos was corrected using gold weights inserted into the upper eyelid. The advantages and disadvantages of this surgical technique are reviewed. Medial canthoplasty and lateral canthoplasty were performed to rectify paralytic ectropion. Ancillary procedures included browpexy, upper-lid blepharoplasty, and temporalis sling. The results were excellent in 23 of 25 patients and good in the remaining two. After a minimum of 6 months' follow-up, there were no complications. The authors believe that the above procedures will yield consistently excellent cosmetic and functional results in patients with paralysis of the eyelids.

Mandibular reconstruction with transforming growth factor-beta1.

HYPOTHESIS: Transforming growth factor-beta1 (TGF-beta1) plus demineralized bone matrix (DBM) will reconstruct a critical mandibular defect devoid of periosteum in a canine model. STUDY DESIGN: Randomized, blinded, placebo-controlled, prospective animal pilot study. METHODS: Canine critical mandibular defects devoid of periosteum were reconstructed with DBM (group 1, n = 3) and DBM plus TGF-beta1 (250 microg TGF-beta1/g DBM) (group 2, n = 3). Radiologic, histologic, and biomechanical testing was performed on the test group and control group specimens at 12 weeks after implantation. RESULTS: A palpable bone bridge was present in the group 2 subjects 5 to 6 weeks after implantation and was never present in the group 1 subjects. Radiologic and histologic examination at the time of harvest (12 weeks after implantation) demonstrated a solid bone bridge in the group 2 subjects and a fibrous union in the group 1 subjects. Group 2 specimens demonstrated failure in four-point bending testing at an average maximum moment of 9.9 +/- 2.2 N-m. This value was 9.4% of the maximum moment of the contralateral nonoperated side. Group 1 specimens were palpably flexible on plate removal and had a biomechanical strength of 0. The difference in strength between group 1 and group 2 was statistically significant (P < 0.02), supporting the hypothesis that the addition of TGF-beta1 to the DBM carrier resulted in the formation of significantly stronger bone in the critical gap. CONCLUSION: The addition of TGF-beta1 to DBM results in healing of a critical bone defect devoid of periosteum in a higher mammalian model.

Bone-inducing implants in head and neck surgery: an experimental study.

The use of autologous bone for head and neck reconstruction requires a separate harvesting procedure which provides limited quantities of bone that may become infected or undergo resorption after being implanted. In this study, a collagen/ceramic carrier containing osteoinductive factor extract (OFE) was used in a rabbit facial augmentation model. Bone-inducing activity of these implants were evaluated in subcutaneous, intramuscular, and subperiosteal sites. Implants with (test) and without OFE (control) were placed on opposite sides of the face in 40 rabbits, and were harvested at 21 days. Bone formation was evaluated by implant alkaline phosphatase determinations and histomorphometry. Osteoblastic activity, bone formation, and preservation of facial augmentation were noted in the OFE implants, showing maximal bone formation when implanted subperiosteally. Control (no OFE) and demineralized bone implants showed no bone formation. Before these implants can be used clinically, novel bone-inducing factors must be manufactured by recombinant deoxyribonucleic acid (DNA) methodology to verify activity of the homogeneous molecule which would be free of other proteins or infectious agents.

Ptosis and blepharoplasty surgery.

Acquired senile ptosis of the upper eyelid is a common condition in the elderly population and is often accompanied by varying amounts of dermatochalasis, which may mask its presence. Blepharoplasty of the ptotic lid, without repair of the ptosis, may result in exaggeration of the drooping eyelid postoperatively. Acquired senile ptosis is produced by dehiscence or disinsertion of the levator aponeurosis and is characterized by a high or absent eyelid crease, thinning of the upper eyelid tissue, and normal levator function. Frequent causes of acquired ptosis include dermatochalasis, eyelid edema from trauma or allergies, previous ocular surgery, or use of contact lenses. When discovered, repair of the ptosis should be performed at the time of blepharoplasty to produce the best functional and cosmetic result. It is important for every surgeon who performs blepharoplasties to be aware of the presentation and management of acquired senile ptosis for consistent surgical results.

Myofibroblasts in head and neck surgery. An experimental and clinical study.

Myofibroblasts in human granulation tissue have many of the structural and functional characteristics of smooth-muscle cells and appear to be responsible for wound contraction. They have also been identified in contracted scar tissue in nongranulation wounds. In this report, their role in head and neck wound healing will be explored utilizing transmission electron microscopy and immunoperoxidase techniques with antibodies to the intermediate filament vimentin and to muscle-restricted actins. In piglets, high-tension, low-tension, and granulating wounds were created and studied with serial biopsy specimens. Results showed few myofibroblasts in either the high- or low-tension wounds and multiple myofibroblasts in the granulating wounds. In the clinical studies, the immunoperoxidase technique with monoclonal antibody to muscle-specific actins proved most useful in identifying myofibroblasts. Myofibroblasts were present in granulating wounds and hypertrophic scars. They were not widely present in mature keloids.

The effect of relaxin on tissue expansion.

Relaxin is a 56-amino acid polypeptide that produces relaxation of the pubic ligament. Ten young male pigs were implanted with tissue expanders and osmotic pumps. The pumps in five animals contained recombinant human relaxin to produce a serum relaxin level of 1 ng/mL. The other five pumps contained saline. Repeated measurements of the pressure-volume expansion curves showed a significant decrease in the pressure needed to fill the expanders in the relaxin group compared with the control group. Dermal thickness in the control group and epidermal thickness in both control and experimental groups were increased on histomorphometric measurement. No adverse effects were seen in the relaxin group. Relaxin facilitates tissue expansion in pigs without affecting dermal thickness.

Vasoconstrictors in facial plastic surgery.

The effectiveness of local anesthetics is improved by the addition of a vasoconstrictor with an increased duration of action and the ability to decrease both systemic toxic reactions and local bleeding. Epinephrine, the standard drug for vasoconstriction, has some limitations due to potential cardiac and local toxic effects. Using an animal model, we compared the effects of various concentrations of epinephrine and two other vasoconstrictors, phenylephrine hydrochloride and felypressin, on local blood flow. We also examined the local effects of bupivacaine hydrochloride and ropivacaine hydrochloride, a new local anesthetic. We found that felypressin was as effective a vasoconstrictor as epinephrine, with fewer potential toxic reactions. Phenylephrine (Neo-Synephrine), on the other hand, was less effective, with a shorter duration of action. As expected, bupivacaine produced vasodilation, while ropivacaine was found to have vasoconstrictive properties.

Suspended circummandibular wire fixation for mixed-dentition pediatric mandible fractures.

OBJECTIVE: To introduce and evaluate the technique of cirummandibular wires with piriform rim suspension (CMW-PRS) combined with arch bars and a fracture site bridle in the treatment of mixed-dentition pediatric mandible fractures. DESIGN: Five male patients (mean age, 8.2 years [age range, 7-10 years]) with an isolated mixed-dentition mandible fracture were treated with the CMW-PRS technique at the University of Texas Health Science Center, San Antonio, from 1985 to 1987 and at the University of Missouri, Columbia, from 1992 to 1995. Clinical and radiographic fracture healing, somatosensory status, and complications were evaluated. RESULTS: All patients demonstrated clinical union to their preinjury occlusion by 3 or 4 weeks. They remained without complications until they were no longer available for follow-up. Panoramic radiographs supported the findings of clinical examinations throughout the study, and no radiographic abnormalities were found. There were no somatosensory disturbances of the lingual or mental/inferior alveolar nerves. One patient required a tracheostomy unrelated to the procedure. CONCLUSION: The CMW-PRS technique combined with arch bars and a fracture site bridle wire achieved equivalent historical results when compared with the dental splint. The potential advantages and disadvantages of the CMW-PRS technique compared with those of monocortical bone plating, as well as the significant advantages of the CMW-PRS over the dental splint, are discussed in the text.

Demineralized bone. Implant resorption with long-term follow-up.

The osteoinductive properties of demineralized bone have stimulated its use in facial skeletal augmentation and reconstruction. Demineralized bone has been shown to induce phenotypic conversion of mesenchymal cells into osteoblasts, with bone formation within 29 days (osteoinduction). In this clinical study, 75 demineralized bone implants were followed up from 1 to 48 months (average follow-up, 14.3 months). There were 41 major dorsal implants, with an average degree of resorption of 50.7%. Eight dorsal implants were followed up for more than 24 months, with an 82.5% degree of resorption. Overall resorption for all implants was 49%. Major factors contributing to implant resorption included lack of surrounding mesenchymal cells and inadequate contact between host tissue and bone-inducing surface area. Other factors included infection, poor vascularity, and compression of the implant. Demineralized bone has an unacceptably high resorption rate and should only be used in highly selective cases where the implant can be positioned in a site rich in primitive mesenchymal or bone-forming cells.