Jarid2 Is Implicated in the Initial Xist-Induced Targeting of PRC2 to the Inactive X Chromosome.

During X chromosome inactivation (XCI), the Polycomb Repressive Complex 2 (PRC2) is thought to participate in the early maintenance of the inactive state. Although Xist RNA is essential for the recruitment of PRC2 to the X chromosome, the precise mechanism remains unclear. Here, we demonstrate that the PRC2 cofactor Jarid2 is an important mediator of Xist-induced PRC2 targeting. The region containing the conserved B and F repeats of Xist is critical for Jarid2 recruitment via its unique N-terminal domain. Xist-induced Jarid2 recruitment occurs chromosome-wide independently of a functional PRC2 complex, unlike at other parts of the genome, such as CG-rich regions, where Jarid2 and PRC2 binding are interdependent. Conversely, we show that Jarid2 loss prevents efficient PRC2 and H3K27me3 enrichment to Xist-coated chromatin. Jarid2 thus represents an important intermediate between PRC2 and Xist RNA for the initial targeting of the PRC2 complex to the X chromosome during onset of XCI.

Arterial coupling for microvascular free tissue transfer.

OBJECTIVE: The purpose of this study was to demonstrate the efficacy of arterial coupling. STUDY DESIGN: Retrospective data were collected in a consecutive series of 124 patients undergoing surgical resection of head and neck tumors followed by free tissue transfer (FTT). METHODS AND MEASURES: The Unilink coupling device was used to perform arterial and venous anastomosis. Flap survival and thrombosis of the arterial anastomoses were determined. RESULTS: A total of 124 consecutive patients underwent a total of 127 microvascular FTTs. Reconstruction included 90 radial forearm, 26 fibula, 9 rectus abdominis, and 2 iliac crest myocutaneous free flaps. There were four (3.2%) complications related to arterial insufficiency in our series, three of which were salvageable. There were three (2.4%) flap failures, resulting in an overall free flap survival rate of 97.6 percent. CONCLUSION: The flap survival with the Unilink Microvascular Anastomotic System is similar to that of standard suture techniques. Use of a coupler device is the preferred method in performing microvascular FTT at our institution.

Synthetic facial implants.

This article presents a range of synthetic implant materials for use in facial plastic surgery. The authors discuss alternatives to autogenous tissue transfer in terms of biocompatibility, technique, complications, controversies, and cautions. The reader is presented information about a range of synthetic implant materials such as silicone, polyester fiber, polyamide mesh, metal, polyethylene, polyacrylamide gel, hydroxyapatite, polylactic acid, collagen, and others.

Arterial coupling for microvascular free tissue transfer in head and neck reconstruction.

OBJECTIVE: To demonstrate the efficacy of arterial coupling. DESIGN: We report our experience in head and neck reconstruction with the Unilink Microvascular Anastomotic System (Synovis MCA, Birmingham, Ala). Data were collected in a consecutive series of 49 patients undergoing composite resection of head and neck tumors followed by free tissue transfer. SETTING: All patient care took place at Yale-New Haven Hospital, New Haven, Conn, a university-based tertiary care facility. PATIENTS: Forty-nine consecutive patients aged 43 to 85 years underwent a total of 50 microvascular free tissue transfers using the Unilink coupling device. There were 18 women and 31 men, and the following 3 types of flaps were performed: radial forearm (n = 36), fibula (n = 12), and rectus abdominus (n = 2). INTERVENTIONS: The Unilink coupling device was used in this case series. Each arterial and venous anastomosis was performed with the coupling device. Free tissue transfers were monitored clinically and outcomes were recorded. MAIN OUTCOME MEASURES: Flap survival and thrombosis of the arterial anastomoses were determined, as was median length of stay. RESULTS: There were no flap failures in the series. Of the 50 coupled arterial anastomoses, the predominant coupler size used was 2.5 mm in diameter. Reconstructions included 36 radial forearm, 12 fibular osteocutaneous, and 2 rectus abdominus myocutaneous free flaps. One intraoperative arterial thrombosis occurred, requiring hand-sewn anastomosis, and another pulled away from the intact coupler in a steroid-dependent patient. There were no complications related to technical performance of the coupling device. The median length of stay was 14 days. CONCLUSION: While hand-sewn anastomoses in free tissue transfer remain the preferred technique for many microsurgeons, use of the coupler is a viable alternative to sutured anastomoses.

Bile-induced laryngitis: is there a basis in evidence?

Most agree that bile reflux occurs with regularity in an otherwise healthy population and that biliary and acid reflux may play a synergistic role in damaging esophageal mucosa. But to what extent is laryngeal mucosa at risk? We constructed a saline-controlled rat model (n = 40) in which active component solutions of bile--taurocholic acid and chenodeoxycholic acid--were applied to intact laryngeal mucosa at various pH levels. Histologic sampling of the laryngeal mucosa allowed inflammation scores to be generated by a pathologist blinded to the solutions used. Both taurocholic acid at acid pH and chenodeoxycholic acid at basic pH preferentially induced statistically greater inflammation scores than did the saline control, approaching or exceeding inflammation scores attributed to hydrochloric acid at pH 1.2. These observations may clarify reasons for failure to uniformly control laryngeal injury by adequate suppression of gastric acid alone and may further justify alternative methods of laryngeal protection in patients refractory to adequate acid control.