Use of botulinum toxin to prevent facial nerve stimulation following cochlear implantation.

Facial nerve stimulation can develop because of the electric fields generated from an activated cochlear implant. This problem can usually be ameliorated by reducing or eliminating the current through the electrodes causing the undesirable stimulation. Occasionally there may be numerous electrodes that have to be deactivated in order to eliminate the facial nerve stimulation, and this may result in a marked reduction of auditory benefit to the cochlear implant user. Botulinum toxin causes transient neuromuscular blockade and has been shown to be effective in reducing or eliminating facial nerve hyperactivity due to a variety of causes. This report details the use of botulinum toxin in a patient with a cochlear implant who developed excessive facial nerve stimulation that necessitated the deactivation of 15 of the implant's 22 electrodes. After treatment with botulinum toxin, twice as many electrodes could be comfortably activated without causing facial nerve stimulation. The dynamic range was increased in 4 of the remaining 6 electrodes that were activated prior to treatment. The patient reported a marked improvement in sound quality and understanding of speech without lipreading as compared to her pretreatment performance. Treatment with botulinum toxin appears to be useful for patients who have excessive facial nerve stimulation after cochlear implantation.

Use of demineralized bone as an osteoinductive orbital enucleation implant in the rabbit.

Implanted allogeneic demineralized bone particles (DBP) may be transformed into endochondral bone by inductive or conductive new bone formation. Using a rabbit model, enucleation or evisceration was performed, and DBP was implanted into the socket. Histology confirmed endochondral bone formation in both groups. A morphologic difference existed between enucleation and evisceration: compact bone was produced following evisceration, and cancellous bony spheres were formed following enucleation. Serial quantitative computed tomography (qCT) was performed to monitor mineral density and proved to be an ideal technique to monitor bone mineralization noninvasively in the postoperative orbit. Bone mineral density (BMD, mg/ml) increased approximately 300% in DBP implanted orbits when compared to controls at 6 weeks. The ideal mass/volume ratio of DBP to socket volume was 400 mg/ml. The rapidly formed bone is well vascularized and creates a stable integrated orbital implant, following enucleation and evisceration surgery. DBP implantation into the central orbit results in inductive bone formation with interesting potential in socket and orbit reconstruction.

Correction of vertical retraction of the lower lid with an orbicularis hammock.

Radical maxillectomy is the treatment of choice for malignant tumors of the paranasal sinuses and nasopharynx. Unfortunately, adverse side effects include ectropion, diplopia, and nasolacrimal duct obstruction. We describe a new technique for repair of the cicatricial ectropion and vertical retraction of the lower lid.

Cellular retinol- and retinoic acid-binding proteins in transformed mammalian cells.

Extracts prepared from several lines of transformed cells were examined for the presence of cellular binding proteins specific for retinoids. Extracts of human retinoblastoma cell line WERI-Rb1 contained a cellular binding protein specific for retinoic acid, whereas extracts of human retinoblastoma cell line Y-79 contained cellular binding proteins for both retinol and retinoic acid. Upon purification, the latter two binding proteins proved to have properties similar to those of the corresponding proteins obtained from bovine retina. Smaller amounts of these binding proteins were detected in extracts of undifferentiated and differentiated neuroblastoma and McCoy cells. HeLa and rat glioma cells had no detectable amount of binding proteins. The 11-cis-retinal-binding protein, present in extracts of human, rat, and bovine retina, was not found in any of the cell lines examined.

Dexamethasone inhibition of experimental endothelial cell proliferation in retinal venules.

The observation that endothelial cell proliferation in retinal blood vessels is induced by ocular trauma in rats has been extended to mice. Indomethacin, 10 mg/kg/day, failed to block incorporation of tritiated thymidine into nuclei of venular endothelial cells in rat retinas observed 40 hr after puncturing the lens, but dexamethasone effectively suppressed tritiated thymidine incorporation, with 50% inhibition obtained with 0.2 mg/kg/day. The prostaglandin pathway does not appear essential to the activation of endothelial cell proliferation in this system.

Amino acids and peptides. XLII. Synthesis of an octapeptide sequence (A20-A27) of rubredoxin.

A protected octapeptide corresponding to a section found in the first half of the protein chain of rubredoxin has been prepared by standard peptide methods. Alternative approaches of this fragment are discussed in some detail. This work completes the series of subunits necessary to synthesize the molecule.