Glottic closure patterns: type I thyroplasty versus type I thyroplasty with arytenoid adduction.

OBJECTIVES/HYPOTHESIS: The goal of laryngeal framework surgery in patients with unilateral vocal fold paralysis is to improve glottic closure by medializing the paralyzed vocal fold. Type I thyroplasty (Th) and arytenoid adduction (AA) are two of the most commonly performed procedures. Two of the main rationales for performing an AA are to improve closure of the posterior glottis and correct vertical height discrepancy. The purpose of this study was to evaluate if AA with Th yields better posterior glottic closure and vertical height equality than Th alone. STUDY DESIGN: Retrospective. METHODS: Using visual analog scales, three blinded reviewers evaluated glottic closure patterns in patients who underwent Th or Th with AA. Pre- and postoperative videostroboscopic examinations of 45 patients with unilateral vocal fold paralysis, who underwent laryngeal framework surgery, were evaluated. RESULTS: No significant difference was identified in postoperative scores for midmembranous glottis closure (P=0.282), closure just anterior to the vocal processes (P=0.426), respiratory glottis closure (P=0.158), or vertical height discrepancy (P=0.113). CONCLUSIONS: Although larger glottic gaps and vertical height discrepancies may lead some surgeons to predict that an AA is warranted, the usefulness of AA may not always be related to these parameters. Ultimately, voice improvement and not geometry should guide the surgeon's decision making.

Intron Evolution and Information processing in the DNA polymerase alpha gene in spirotrichous ciliates: a hypothesis for interconversion between DNA and RNA deletion.

BACKGROUND: The somatic DNA molecules of spirotrichous ciliates are present as linear chromosomes containing mostly single-gene coding sequences with short 5' and 3' flanking regions. Only a few conserved motifs have been found in the flanking DNA. Motifs that may play roles in promoting and/or regulating transcription have not been consistently detected. Moreover, comparing subtelomeric regions of 1,356 end-sequenced somatic chromosomes failed to identify more putatively conserved motifs. RESULTS: We sequenced and compared DNA and RNA versions of the DNA polymerase alpha (pol alpha) gene from nine diverged spirotrichous ciliates. We identified a G-C rich motif aaTACCGC(G/C/T) upstream from transcription start sites in all nine pol alpha orthologs. Furthermore, we consistently found likely polyadenylation signals, similar to the eukaryotic consensus AAUAAA, within 35 nt upstream of the polyadenylation sites. Numbers of introns differed among orthologs, suggesting independent gain or loss of some introns during the evolution of this gene. Finally, we discuss the occurrence of short direct repeats flanking some introns in the DNA pol alpha genes. These introns flanked by direct repeats resemble a class of DNA sequences called internal eliminated sequences (IES) that are deleted from ciliate chromosomes during development. CONCLUSION: Our results suggest that conserved motifs are present at both 5' and 3' untranscribed regions of the DNA pol alpha genes in nine spirotrichous ciliates. We also show that several independent gains and losses of introns in the DNA pol alpha genes have occurred in the spirotrichous ciliate lineage. Finally, our statistical results suggest that proven introns might also function in an IES removal pathway. This could strengthen a recent hypothesis that introns evolve into IESs, explaining the scarcity of introns in spirotrichs. Alternatively, the analysis suggests that ciliates might occasionally use intron splicing to correct, at the RNA level, failures in IES excision during developmental DNA elimination.

Reciprocal fusions of two genes in the formaldehyde detoxification pathway in ciliates and diatoms.

During the course of a pilot genome project for the ciliate Oxytricha trifallax, we discovered a fusion gene never before described in any taxa. This gene, FSF1, encodes a putative fusion protein comprising an entire formaldehyde dehydrogenase (FALDH) homolog at one end and an S-formylglutathione hydrolase (SFGH) homolog at the other, two proteins that catalyze serial steps in the formaldehyde detoxification pathway. We confirmed the presence of the Oxytricha fusion gene in vivo and detected transcripts of the full-length fusion gene. A survey of other large-scale sequencing projects revealed a similar fusion protein in a distantly related ciliate, Tetrahymena thermophila, and a possible fusion of these two genes in the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana, but in the reverse order, with the SFGH domain encoded upstream of the FALDH domain. Orthologs of these fusion proteins may be widespread within the ciliates and diatoms.