Faculty Bibliography

Organelle transport by myosin-V is down-regulated during mitosis, presumably by myosin-V phosphorylation. We used mass spectrometry phosphopeptide mapping to show that the tail of myosin-V was phosphorylated in mitotic Xenopus egg extract on a single serine residue localized in the carboxyl-terminal organelle-binding domain. Phosphorylation resulted in the release of the motor from the organelle. The phosphorylation site matched the consensus sequence of calcium/calmodulin-dependent protein kinase II (CaMKII), and inhibitors of CaMKII prevented myosin-V release. The modulation of cargo binding by phosphorylation is likely to represent a general mechanism regulating organelle transport by myosin-V

The flow of activity in the cortical microcircuitry is poorly understood. We use calcium imaging to reconstruct, with millisecond and single-cell resolution, the spontaneous activity of populations of neurons in unstimulated slices from mouse visual cortex. We find spontaneous activity correlated among networks of layer 5 pyramidal cells. Synchronous ensembles occupy overlapping territories, often share neurons, and are repeatedly activated. Sets of neurons are also sequentially activated numerous times. Network synchronization and sequential correlations are blocked by glutamatergic antagonists, even though spontaneous firing persists in many 'autonomously active' neurons. This autonomous activity is periodic and depends on hyperpolarization-activated cationic (H) and persistent sodium (Na(p)) currents. We conclude that the isolated neocortical microcircuit generates spontaneous activity, mediated by a combination of intrinsic and circuit mechanisms, and that this activity can be temporally precise

OBJECTIVES/HYPOTHESIS: To determine the incidence and degree of asymmetry in the height and contour of the ethmoid roof. STUDY DESIGN: Retrospective review of direct coronal paranasal sinus computed tomography (CT) scans. METHODS: Retrospective review of 200 consecutive direct coronal sinus CT scans done at New York University Medical Center from July 25, 2000 to October 11, 2000. The height and contour of the fovea ethmoidalis were examined for symmetry between the right and left sides. When an asymmetry in the height of the fovea ethmoidalis existed, this difference was quantified. RESULTS: In 19 scans (9.5%), there was an asymmetry between the height of the fovea ethmoidalis on the right and left sides. Of these 19, 12 (63.2%) were lower on the right side, whereas 7 (36.8%) were lower on the left. Ninety-six patients (48.0%) demonstrated a contour asymmetry with 'flattening' of the ethmoid roof on one side, 46 on the right and 50 on the left. One patient demonstrated both height and contour asymmetry. The fovea ethmoidalis on the remaining 86 scans (43.0%) was symmetric. CONCLUSIONS: In a patient population with sinus and nasal symptoms, the height and contour of the right and left fovea ethmoidalis were symmetric in less than 50% of individuals. The asymmetry was most often the result of a difference in contour with flattening of the fovea on one side. This underscores the importance of careful preoperative and intraoperative review of paranasal sinus CT scans in patients undergoing endoscopic sinus surgery

Two of the primary cues used to localize the sources of sounds are interaural level differences (ILDs) and interaural time differences (ITDs). We conducted two experiments to explore how practice affects the human discrimination of values of ILDs and ongoing ITDs presented over headphones. We measured discrimination thresholds of 13 to 32 naive listeners in a variety of conditions during a pretest and again, 2 weeks later, during a posttest. Between those two tests, we trained a subset of listeners 1 h per day for 9 days on a single ILD or ITD condition. Listeners improved on both ILD and ITD discrimination. Improvement was initially rapid for both cue types and appeared to generalize broadly across conditions, indicating conceptual or procedural learning. A subsequent slower-improvement stage, which occurred solely for the ILD cue, only affected conditions with the trained stimulus frequency, suggesting that stimulus processing had fundamentally changed. These different learning patterns indicate that practice affects the attention to, or low-level encoding of, ILDs and ITDs at sites at which the two cue types are processed separately. Thus, these data reveal differences in the effect of practice on ILD and ITD discrimination, and provide insight into the encoding of these two cues to sound-source location in humans

In many areas of the nervous system, excitatory and inhibitory synapses are reconfigured during early development. We have previously described the anatomical refinement of an inhibitory projection from the medial nucleus of the trapezoid body to the lateral superior olive in the developing gerbil auditory brain stem. Furthermore, these inhibitory synapses display an age-dependent form of long-lasting depression when activated at a low rate, suggesting that this process could support inhibitory synaptic refinement. Since the inhibitory synapses release both glycine and GABA during maturation, we tested whether GABA(B) receptor signaling could initiate the decrease in synaptic strength. When whole cell recordings were made from lateral superior olive neurons in a brain slice preparation, the long-lasting depression of medial nucleus of the trapezoid body-evoked inhibitory potentials was eliminated by the GABA(B) receptor antagonist, SCH-50911. In addition, inhibitory potentials could be depressed by repeated exposure to the GABA(B) receptor agonist, baclofen. Since GABA(B) receptor signaling may not account entirely for inhibitory synaptic depression, we examined the influence of neurotrophin signaling pathways located in the developing superior olive. Bath application of brain-derived neurotrophic factor or neurotrophin-3 depressed evoked inhibitory potentials, and use-dependent depression was blocked by the tyrosine kinase antagonist, K-252a. We suggest that early expression of GABAergic and neurotrophin signaling mediates inhibitory synaptic plasticity, and this mechanism may support the anatomical refinement of inhibitory connections

OBJECTIVES/HYPOTHESIS: Unilateral vocal fold paralysis resulting in glottal incompetence can cause significant morbidity attributable to impaired speech, swallowing, and ability to protect the airway. Type I thyroplasty in combination with arytenoid adduction is a proven technique for medialization of the paralyzed vocal fold but must be evaluated in light of potential complications following laryngeal framework surgery. STUDY DESIGN AND METHODS: The charts of 237 patients who underwent unilateral vocal fold medialization surgery between July 1, 1991, and August 30, 1999, at a tertiary care cancer referral center were retrospectively reviewed. RESULTS: There were 98 cases of type I thyroplasty alone and 96 cases of type I thyroplasty with arytenoid adduction. The two groups had similar patient characteristics. Mean time of surgery (45 vs. 73 min, P <.0001) and length of hospital stay (1.1 vs. 1.8 d, P <.0001) were increased when arytenoid adduction was performed. Overall improvement of symptoms was similar in both groups (93%-94%), but posterior glottic closure appeared subjectively improved when arytenoid adduction was used (P =.0054). Overall complication rates were slightly higher in the arytenoid adduction group (14% vs. 19%), primarily because of transient vocal fold edema and wound complications (9 vs. 19 cases), but the increase was not statistically significant (P =.1401). Complications warranting medical or surgical intervention occurred in 8% of cases. Two patients who underwent type I thyroplasty with arytenoid adduction required tracheotomy as a consequence of postoperative complications. The three patients who had extrusion of the implant underwent type I thyroplasty alone. CONCLUSION: Using the appropriate technique, the potential benefits of improved glottic function following type I thyroplasty with arytenoid adduction outweigh the small risk of significant complications observed

PURPOSE: This study evaluated the use of enucleation and cryosurgery in the management of odontogenic keratocysts. PATIENTS AND METHODS: This study involved a retrospective review of 26 patients. All of the patients received a combination of enucleation and cryosurgery. Postoperative follow-up consisted of clinical and radiographic examinations. RESULTS: Before enucleation and cryotherapy, 22 of the 26 patients had received previous treatment consisting of enucleation alone. The average time from initial treatment to recurrence was 6.2 years. Twenty-three cases occurred in the mandible, 22 in the posterior (proximal to the canine), and 1 in the anterior mandible. Three cases involved the maxilla. Three of the 26 patients (11.5%) developed a recurrence after treatment. The average time from treatment to recurrence in these 3 patients was 1.6 years (range, 1.2 to 1.9 years). The remaining 23 patients (88.5%) had no evidence of clinical or radiographic recurrence. The average time of follow-up was 3.5 years (range, 2.0 to 10.0 years). CONCLUSIONS: Based on these results, the combination of enucleation and liquid nitrogen cryotherapy may offer patients improved therapy in the management of odontogenic keratocysts

PURPOSE: This study identified the terminal temporal and zygomatic branches of the facial nerve as they enter the orbicularis oculi muscle and related these branches to identifiable surface markings. MATERIALS AND METHODS: The temporal and zygomatic branches of the facial nerve were dissected from 5 preserved cadavers (10 sides). The most superior temporal branch entering the orbicularis oculi muscle was identified and related to the lateral canthus of the eye. A vertical line was passed through this point so that the line was equidistant from the nasal tip and chin point. A line perpendicular to the vertical line through the lateral canthus served as the horizontal scale. Vertical and horizontal lines through the lateral canthus were used to establish the anatomic relationship between the lateral canthus and the branch of the temporal nerve entering the orbicularis oculi muscle. RESULTS: The temporal branch was an average of 2.85 +/- 0.69 cm superior to the lateral canthus and an average of 2.54 +/- 0.43 cm lateral to the lateral canthus as it courses into the orbicularis oculi muscle. At the lateral border of the orbicularis oculi muscle, where the temporal and zygomatic nerves insert into the muscle, the mean vertical distance between the temporal and zygomatic nerves was 1.72 +/- 0.62 cm. CONCLUSION: Incisions superior or inferior and parallel to the course of the facial nerve, can provide access to the fronto zygomatic suture and the superior and lateral orbit without damaging its branches

BACKGROUND AND PURPOSE: Only a small percentage of acute-stroke patients receive thrombolytic therapy because of time constraints and the risks associated with thrombolytic therapy. We sought to determine whether xenon-enhanced CT (XeCT) cerebral blood flow (CBF) and/or CT angiography (CTA) in conjunction with CT can distinguish subgroups of acute ischemic stroke victims and thereby better predict the subgroups most likely to benefit and not to benefit from thrombolytic therapy. METHODS: An analysis of 51 patients who had a CT, CTA, and stable XeCT CBF examination within 24 hours of stroke symptom onset was conducted. These initial radiographic studies and National Institutes of Health Stroke Scale score on admission were assessed to determine whether they could predict new infarction on follow-up CT or discharge disposition by use of the Fisher exact test to determine statistical significance. RESULTS: Patients with no infarction on initial CT and normal XeCT CBF had significantly fewer new infarctions and were discharged home more often than those with compromised CBF. The same held true for patients with an open internal carotid artery and middle cerebral artery by CTA and normal CT compared with those with an occluded internal carotid artery and/or middle cerebral artery by CTA. Either was superior to CT and the National Institutes of Health Stroke Scale in prediction of outcome. Both enable the selection of a group of patients not identifiable by CT alone that would do well without being exposed to the risks of thrombolytic therapy. This study included too few patients to statistically assess the role of combining CTA and XeCT CBF information. CONCLUSIONS: The combination of CT, CTA, and Xe/CT CBF does define potentially significant subgroups of patients. The utility of this classification is supported by the observation that CTA and XeCT CBF are superior to CT alone in predicting infarction on follow-up CT and clinical outcome. This information may be useful in selecting patients for acute-stroke treatment

This paper considers the information transmitted in absolute judgments as encoded in a stimulus-response matrix (e.g., see Garner and Hake, 1951). When transmitted information is plotted against the number of stimulus categories in the matrix, one obtains a curve that increases monotonically toward a plateau, which is the maximum information transmittable per stimulus for the particular range of stimuli employed. We demonstrate that although the maximum information transmitted is an attribute of the stimulus continuum itself, the shape of the curve is an empirical property of the stimulus-response matrix, which is determined, in part, by maintaining a constant stimulus category width. Therefore, in principle, each curve of information transmitted vs number of stimulus categories can be determined by a single point: the rightmost point on the graph.