Faculty Bibliography

The correction of sagittal deformities of the chin presents a seemingly simple surgical challenge. However, several authors have reported negative sequelae from such chin surgery, During the past 11 years, the senior author (B.M.Z.) has evaluated more than 100 such cases of adverse results after chin augmentation. Many surgeons, it seems, use chin implants unnecessarily and, thus, get into trouble. Because alloplastic chin augmentation is deceptively easy, it tends to be overused in certain situations. Either the surgeon's evaluation is too narrowly focused or his/her abilities to perform other types of surgery (e.g., osseous genioplasty) are limited. Herein, the authors present a diagnostic evaluation protocol, QUAC (Quick Analysis of the Chin), to assist in avoiding simple mistakes in alloplastic chin augmentation. This protocol will alert the surgeon to situations that, if unrecognized, will cause problems and create an unhappy patient. This article will specifically focus on (1) lower lip analysis; (2) the effect of the labiomental fold; (3) chin pad evaluation, both static and dynamic; (4) the anatomy of the cleft chin; (5) special situations; and (6) how to troubleshoot three common problems. The accompanying article, Chin Surgery II, will present a new operation that treats a chin problem that was previously difficult to correct

Thus far, devastating injuries of the adult brachial plexus have had a poor prognosis. This article presents the possible outcomes of aggressive microsurgical reconstruction in the largest series of patients in North America to date. It should change the pessimistic outlook that has surrounded these lesions. In this study, the outcomes of surgery were analyzed in relation to the type and level of injury, the age of the patient, and the denervation time; stronger donors for neurotization in relation to the various targets were delineated. The results were analyzed in 204 patients with adequate follow-up from a total of 263 patients who were operated on between 1978 and 1996. The mean age of the patients was 25.9 years, and the injuries were caused by high-velocity motor accidents involving avulsion in 55 percent of the patients. Nerve reconstruction included 577 nerve repairs (140 direct neurotizations and 437 cases of nerve grafting). Microneurolysis was performed in 89 cases. Vascularized nerve grafts were used in 120 repairs. Muscle transfers (29 pedicled and 78 free) were used to enhance function. The results were good or excellent in 75 percent of suprascapular nerve reconstructions, 40 percent of deltoid reconstructions, 48 percent of biceps reconstructions, 30 percent of triceps reconstructions, 35 percent of finger-flexion reconstructions, and 15 percent of finger-extension reconstructions. The majority of the patients had protective sensation and pain relief postoperatively

In accessory neuropathy electrodiagnosis, upper trapezius compound muscle action potential (CMAP) latencies and amplitudes are commonly measured. The few prior reports describing middle and lower trapezius recording have traditionally emphasized latency value determination. The utility of amplitude measurement with middle and lower trapezius recording has not, to our knowledge, been previously described in individual patients with accessory neuropathy. We report three patients (A-C) who developed unilateral accessory neuropathy following surgical procedures. Accessory nerve conduction studies were performed with surface recording over the upper, middle, and lower trapezius muscles. Latency values were normal except for a prolonged lower trapezius latency value in patient B. Side-side trapezius amplitude comparisons revealed striking asymmetries from all three recording sites in patients A and B (71-95% CMAP amplitude decrements) and in the lower trapezius recording of patient C. Middle and lower trapezius side-side CMAP amplitude comparisons may increase the sensitivity of accessory neuropathy electrodiagnosis

Angiogenesis is essential to both normal and pathological bone physiology. Vascular endothelial growth factor (VEGF) has been implicated in angiogenesis, whereas transforming growth factor-beta1 (TGF-beta1) modulates bone differentiation, matrix formation, and cytokine expression. The purpose of this study was to investigate the relationship between TGF-beta1 and VEGF expression in osteoblasts and osteoblast-like cells. Northern blot analysis revealed an early peak of VEGF mRNA (6-fold at 3 h) in fetal rat calvarial cells and MC3T3-E1 osteoblast-like cells after stimulation with TGF-beta1 (2.5 ng/ml). The stability of VEGF mRNA in MC3T3-E1 cells was not increased after TGF-beta1 treatment. Actinomycin D inhibited the TGF-beta1-induced peak in VEGF mRNA, whereas cycloheximide did not. Blockade of TGF-beta1 signal transduction via a dominant-negative receptor II adenovirus significantly decreased TGF-beta1 induction of VEGF mRNA. Additionally, TGF-beta1 induced a dose-dependent increase in VEGF protein expression by MC3T3-E1 cells (P < 0.01). Dexamethasone similarly inhibited VEGF protein expression. Both TGF-beta1 mRNA and VEGF mRNA were concurrently present in rat membranous bone, and both followed similar patterns of expression during rat mandibular fracture healing (mRNA and protein). In summary, TGF-beta1-induced VEGF expression by osteoblasts and osteoblast-like cells is a dose-dependent event that may be intimately related to bone development and fracture healing

To explore whether the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin is subject to redox regulation in vivo, we used a luciferase reporter gene construct whose expression was controlled by the transcription factor NF-AT (the nuclear factor of activated T-cells) to monitor intracellular calcineurin activity following redox state perturbations. The NF-AT reporter construct was transfected into Jurkat cells, and luciferase activity was assessed following treatment with phorbol ester and ionomycin in the presence of either hydrogen peroxide or dithiothreitol (DTT). While DTT had no effect, H(2)O(2) completely abrogated NF-AT transactivation in response to stimulation. The inhibitory effect was specific for NF-AT as comparable levels of H(2)O(2) had only minor effects on constitutive transcription factors while an analogous construct under AP-1 control showed a 5-fold stimulation in transactivation in the presence of H(2)O(2). The inhibitory effect of H(2)O(2) was observed up to approximately 3 h following mitogen stimulation, a time point where NF-AT activity begins to increase under normal conditions. Protein serine/threonine phosphatase activities from Jurkat lysate indicated that calcineurin activity was inhibited not only by H(2)O(2) but also by high concentrations of DTT. These results indicate that calcineurin activity is subject to redox regulation in vivo and are discussed in the context of redox reactions involving active site metal ions.

A significant body of literature supports a role for the dura mater underlying cranial sutures in the regulation of sutural fate. These studies have implicated regional differentiation of the dura mater based on association with fusing and patent rat cranial sutures. The purpose of these experiments was to isolate and characterize dural cells associated with fusing (posterior frontal) and patent (sagittal) rat cranial sutures. Six-day-old rats were killed, and the dura mater underlying the posterior frontal and sagittal sutures was harvested. Dural cells were briefly trypsinized and allowed to reach confluence. Two litters (10 animals per litter) were used for each set of experiments. Cells were harvested after the first and fifth passages for analysis of vimentin and desmoplakin expression (characteristic of human meningeal cells), cellular proliferation, density at confluence (a measure of cellular contact inhibition), and alkaline phosphatase production. In addition, bone nodule formation and collagen I production were analyzed in first passage cells. The results indicate that suture-derived dural cells can be established and that these cells coexpress vimentin and desmoplakin. In addition, it is demonstrated that first-passage sagittal suture-derived dural cells proliferate significantly faster and have decreased cellular contact inhibition than posterior frontal suture-derived cells (p < 0.01). Finally, it is shown that suture-derived dural cells have osteoblast-like properties, including alkaline phosphatase production, collagen I expression, and bone nodule formation in vitro. The possible mechanisms by which regional differentiation of suture-derived dural cells occur are discussed