Lewis J. Overton

Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent in Drosophila

The Bloom syndrome helicase, BLM, has numerous functions that prevent mitotic crossovers. We used unique features of Drosophila melanogaster to investigate origins and properties of mitotic crossovers that occur when BLM is absent. Induction of lesions that block replication forks increased crossover frequencies, consistent with functions for BLM in responding to fork blockage. In contrast, treatment with hydroxyurea, which stalls forks, did not elevate crossovers, even though mutants lacking BLM are sensitive to killing by this agent. To learn about sources of spontaneous recombination, we mapped mitotic crossovers in mutants lacking BLM. In the male germline, irradiation-induced crossovers were distributed randomly across the euchromatin, but spontaneous crossovers were nonrandom. We suggest that regions of the genome with a high frequency of mitotic crossovers may be analogous to common fragile sites in the human genome. Interestingly, in the male germline there is a paucity of crossovers in the interval that spans the pericentric heterochromatin, but in the female germline this interval is more prone to crossing over. Finally, our system allowed us to recover pairs of reciprocal crossover chromosomes. Sequencing of these revealed the existence of gene conversion tracts and did not provide any evidence for mutations associated with crossovers. These findings provide important new insights into sources and structures of mitotic crossovers and functions of BLM helicase.

Trial Vocal Fold Injection Predicts Thyroplasty Outcomes in Nonparalytic Glottic Incompetence

Objectives: Trial vocal fold injection (TVFI) may be used prior to permanent medialization when voice outcome is uncertain. We aimed to determine whether voice outcomes of TVFI are predictive of, or correlate with outcomes after type I Gore-Tex medialization thyroplasty (GMT) in patients with nonparalytic glottic incompetence (GI). Methods: Thirty-five patients with nonparalytic GI who underwent TVFI followed by GMT were retrospectively reviewed. Change in voice-related quality of life (VRQOL) after TVFI was compared to change in VRQOL 3 to 9 months after GMT. Similar comparisons were made for change in glottal function index (GFI) and change in grade, roughness, breathiness, asthenia, and strain (GRBAS). Sample correlation coefficients were calculated. Results: Change in VRQOL after TVFI showed good correlation with change in VRQOL after GMT, r = 0.55. Change in GFI after TVFI showed strong correlation with change in GFI after GMT, r = 0.74. Change in GRBAS after TVFI showed excellent correlation with change in GRBAS after GMT, r = 0.90. Conclusion: The TVFI is a useful tool in nonparalytic GI when outcomes from glottic closure procedures are not clear. Voice outcome measures after TVFI strongly correlate with outcomes from GMT. These data may be used to more confidently counsel patients regarding their predicted outcomes of permanent medialization.

Trends in chronic rhinosinusitis research in the past three decades.

The objective of this work was to identify trends in chronic rhinosinusitis (CRS)‐related publications for the past 3 decades.

Longitudinal Voice Outcomes After Type I Gore-tex Thyroplasty for Nonparalytic Glottic Incompetence

Objective: Type I Gore-tex thyroplasty (GTP) for nonparalytic glottic incompetence (GI) results in significantly improved subjective and perceptual voice outcomes. We endeavored to investigate the longitudinal course of voice outcomes measuring the same patients across time points stratified by diagnostic subgroup. Methods: Seventy-five patients with nonparalytic GI treated with GTP in the past 9 years were retrospectively reviewed and grouped according to their primary diagnoses (atrophy, scar, hypomobility, and paresis). Voice outcome measures, Voice-Related Quality of Life (VRQOL), Glottal Function Index (GFI), and GRBAS (grade, roughness, breathiness, asthenia, and strain) for each individual patient and diagnostic subgroup were grouped by time interval following surgery: 0 to 90 days, 3 to 9 months, 9 to 18 months, 18 to 36 months, 3 to 5 years, and 5 to 10 years. Results: Across all diagnoses, statistically significant improvement in VRQOL was maintained at 3 to 5 years (P = .03) and GFI at 5 to 10 years (P = .02). The GRBAS showed statistically significant improvements out to 18 to 36 months (P = .02). In the subgroup analysis, hypomobility/paresis patients maintained significant improvement voice measures longer than patients with other diagnoses. As a group, scar patients did not show statistically significant postoperative improvement in VRQOL or GFI at any of the tested time points. Conclusions: Gore-tex thyroplasty provides durable improvement in subjective and perceptual voice outcomes for patients with nonparalytic GI. Patients treated for hypomobility/paresis have the most durable vocal outcomes followed by atrophy and lastly, scar.

Conscious Perception of Facial Asymmetry in a Unilateral Cleft Lip Model

Objective: Lip asymmetry after a unilateral cleft lip repair can be perceived as an unsatisfactory result. The objective of this study is to determine the degree of upper lip asymmetry and/or nasal alar hooding required for recognition of asymmetry in a simulated model of unilateral cleft lip. Design: A model of unilateral cleft lip was created using digital morphing software to simulate asymmetries in vermilion height and nasal hooding in photographs of children. Volunteers were shown photographs for different time intervals and with varying degrees of asymmetry. Ability to detect facial asymmetry was recorded and analyzed. Setting: This study was conducted by surveying layperson volunteers in public community settings. Participants: 108 layperson volunteers were randomly surveyed. Main Outcome Measures: The primary outcome measure was a reported lip or nose asymmetry by the volunteers. Proportions and corresponding 95% confidence intervals were obtained to estimate the probability of reporting an asymmetry at 3- and 10-second intervals. Results: After 3- and 10-second exposure, labial asymmetry was perceived by ≥50% of subjects at 2 mm (62%, P = .001) and 1 mm (89%, P < .0001), respectively. Nasal asymmetry was detected by <50% of subjects at 3 seconds, but ≥50% perceived a 3-mm alteration at 10 seconds (64%, P < .0001). Photographs with combined nasal and labial modification did not lower the threshold for asymmetry perception compared to either deformity alone. Conclusions: This study is the first to determine a predictable millimeter threshold for perceived asymmetry in cleft lip deformity using a digital model.

The Reverse-Flow Facial Artery Buccinator Flap for Skull Base Reconstruction: Key Anatomical and Technical Considerations

Objective To highlight key anatomical and technical considerations for facial artery identification, and harvest and transposition of the facial artery buccinator (FAB) flap to facilitate its future use in anterior skull base reconstruction. Only a few studies have evaluated the reverse-flow FAB flap for skull base defects. Design Eight FAB flaps were raised in four cadaveric heads and divided into thirds; the facial arterys course at the superior and inferior borders of the flap was measured noting in which incisional third of the flap it laid. The flaps reach to the anterior cranial fossa, sella turcica, clival recess, and contralateral cribriform plate were studied. A clinical case and operative video are also presented. Results The facial artery had a near vertical course and stayed with the middle (⅝) or posterior third (⅜) of the flap in the inferior and superior incisions. Seven of eight flaps covered the sellar/planar regions. Only four of eight flaps covered the contralateral cribriform region. Lastly, none reached the middle third of the clivus. Conclusions The FAB flap requires an understanding of the facial arterys course, generally seen in the middle third of the flap, and is an appropriate alternative for sellar/planar and ipsilateral cribriform defects.

Carotid artery and lower cranial nerve exposure with increasing surgical complexity to the parapharyngeal space

To investigate the extent of carotid artery exposure attained, including the identification of the external carotid branches and lower cranial nerves in five sequential external approaches to the parapharyngeal space, and to provide an anatomical algorithm.

Hypovolemic shock after labial and lingual frenulectomy: A report of two cases

Lingual and labial frenulectomy are commonly performed as an outpatient procedure, either in an office setting or under general anesthesia. Frenulectomy is generally regarded by both otolaryngologists and dentists as a straightforward and low-risk procedure with limited evidence-based indications and similarly few contraindications. We describe two cases of hypovolemic shock occurring after outpatient frenulectomy requiring emergent interventions of cardiopulmonary resuscitation and blood transfusion. These rare, but life-threatening outcomes warrant recognition as potential complications for the presumed benign labial and lingual frenulectomy. We additionally briefly review indications for upper labial and lingual frenulectomy.