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Biomedical subjects

W F Larrabee

Publications and source records attributed to W F Larrabee.

At least 19 recordsLinked to original sources
PubMed1992

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.

Animals↗
PubMed1991

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.

Amides↗
PubMed1991

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.

Alkaline Phosphatase↗
PubMed1990

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.

Bone Density↗
PubMed1990

Intralesional interferon gamma treatment for keloids and hypertrophic scars.

Keloids and hypertrophic scars are characterized by excessive collagen formation. Interferon gamma is a lymphokine that can down-regulate collagen synthesis in vitro and in vivo and, therefore, has potential therapeutic benefit in the management of abnormal scars. Intralesional scar injections of interferon gamma were performed to determine the tolerance toxicity and to obtain preliminary evidence for the efficacy of this treatment in the management of hypertropic and keloid lesions. All scars decreased in linear dimensions and flattened out. Five of 10 scars studied decreased at least 50% in linear dimensions. Interferon gamma can safely be administered intralesionally once per week up to a dosage of 0.05 mg for 10 weeks with no serious toxic effects. The commonest reported side effect was a mild headache.

Adult↗
PubMed1990

Efficacy of steroids and hyperbaric oxygen on survival of dorsal skin flaps in rats.

This study was designed to determine if steroids improved skin flap survival in rats, and if steroids and hyperbaric oxygen (HBO) showed an additive beneficial effect. Cranially based, 3 x 9 cm dorsal skin flaps were raised in 60 adult rats. All animals received either intramuscular methylprednisolone (30 mg/kg) or an equal volume of intramuscular saline solution placebo 24 hours and 1 hour before, and 24 hours and 48 hours after, flap elevation. Treatment for animals receiving HBO was begun within 5 hours after flap elevation. The regimen consisted of two 90-minute treatments of 100% oxygen at 2.4 atm separated by 5-hour intervals or room air per day for 3 consecutive days. The 60 rats were divided equally into four treatment groups, as follows: group A, flap elevation alone (control); group B, flap plus steroids; group C, flap plus HBO; and group D, flap plus steroids plus HBO. Surviving flap length was measured by visual inspection 7 days after flap elevation. The mean surviving flap length for group A was 4.9 cm, for group B it was 6.4 cm, for group C it was 6.7 cm, and for group D it was 6.5 cm. The approximately 30% to 36% improvement in surviving flap length was highly statistically significant (p less than 0.006) when compared with controls. However, no statistically significant difference was found between the three treatment modalities. These findings indicate that in a rat dorsal skin flap model, perioperative steroids improve skin flap viability, and that steroids alone are as efficacious as HBO and as steroids combined with HBO.

Animals↗
PubMed1990

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.

Cranial Nerve Neoplasms↗
PubMed1990

Design of local skin flaps.

Design of the optimal local skin flap to repair a specific facial defect requires an understanding of the geometry of the various flaps, local facial anatomy, and the biomechanics of skin and soft tissue. The creative integration of these variables is one of the most challenging areas of facial plastic surgery. This article discusses some general principles of flap design with emphasis on the importance of skin tension and its distribution in preventing complications and maximizing the use of local tissue in difficult reconstructive situations.

Biomechanical Phenomena↗
PubMed1989

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.

Aged↗
PubMed1989

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.

Adult↗
PubMed1989

Immediate repair of facial defects.

Primary closures or repairs with local skin flaps generally give better aesthetic results than skin grafts, with a few exceptions. This article discusses some of the more common closures that make use of local skin flaps, with particular emphasis on which flaps to employ in specific circumstances.

Dermatologic Surgical Procedures↗