Are Ar3SbCl2 Species Lewis Acidic? Exploration of the Concept and Pnictogen Bond Catalysis Using a Geometrically Constrained Example.

As part of our investigations into the Lewis acidic behavior of antimony derivatives, we have decided to study the properties of 5-phenyl-5,5-dichloro-λ5-dibenzostibole (1), a dichlorostiborane with an antimony atom confined to a five-membered heterocycle. Our work shows that the resulting geometrical constraints elevate the Lewis acidity of the antimony atom, as confirmed by the crystal structure of 1-THF and the solution study of the interaction of 1 with Ph3PO. The enhanced Lewis acidic properties of 1, which exceed those of simple dichlorostiboranes such as Ph3SbCl2, also become manifest in pnictogen bonding catalysis experiments involving the reductions of imines with Hantzsch ester. The influence of geometrical constraints in the chemistry of this compound is also supported by a computational activation strain analysis as well as by an energy decomposition analysis of a model Me3PO adduct.

Mapping Critical Residues in ATG11's Coiled-Coil 2 Domain that Block Multiple Interactions and Disrupt Selective Autophagy.

Selective autophagy is a conserved subcellular process that maintains the health of eukaryotic cells by targeting damaged or toxic cytoplasmic components to the vacuole/lysosome for degradation. A key player in the initiation of selective autophagy in S. Cerevisiae (baker's yeast) is a large adapter protein called Atg11. Atg11 has multiple predicted coiled-coil domains and intrinsically disordered regions, is known to dimerize, and binds and organizes other essential components of the autophagosome formation machinery, including Atg1 and Atg9. We performed systematic directed mutagenesis on the coiled-coil 2 domain of Atg11 in order to map which residues were required for its structure and function. Using yeast-2-hybrid and coimmunoprecipitation, we found only three residues to be critical: I562, Y565, and I569. Mutation of any of these, but especially Y565, could interfere with Atg11 dimerization and block its interaction with Atg1 and Atg9, thereby inactivating selective autophagy.

Orbital Trauma.

The orbit is contained within a complex bony architecture with overlying soft tissue that involves many important anatomical structures. Orbital trauma is a frequent cause of damage to these structures. The authors review the literature on reconstructive techniques focusing on fractures of the orbital rim, orbital roof, orbital floor, medial orbital wall, and naso-orbito-ethmoid complex. A thorough literature review was conducted using PubMed analyzing articles relevant to the subject matter. Various search terms were used to identify articles regarding orbital trauma presentation, diagnosis, management, as well as postoperative complications. Articles were examined by all authors and pertinent information was gleaned for the purpose of generating this review. Orbital trauma can result in a wide variety of complications in form and function. Not all orbital fractures require operative repair. However, bony disruption can cause enophthalmos, hypophthalmos, telecanthus, epiphora, cerebrospinal fluid leaks, orbital hematoma, and even blindness to name a few. Timing of operative repair as well as reconstructive method is dictated by the patient's individual presentation. Successful fracture management requires a detailed understanding of the anatomy and pathophysiology to ensure restoration of the patients' preoperative state. Orbital trauma encompasses a wide variety of mechanisms of injury and resulting fracture patterns. A variety of surgical approaches to the orbit exist as has been discussed allowing the surgeon access to all area of interest. Regardless of the fracture complexity, the principles of atraumatic technique, anatomic reduction, and stable fixation apply in all cases.

Cranioplasty Using a Mixture of Biologic and Nonbiologic Agents.

IMPORTANCE: A surgeon faces challenges with cranioplasty techniques to achieve a successful result with relatively few complications. OBJECTIVE: To describe a unique technique for incorporating both biologic autologous bone and nonbiologic allograft materials for defect coverage in cranioplasty with favorable outcomes and low occurrence of complications. DESIGN, SETTING, AND PARTICIPANTS: A retrospective medical records review of all 26 patients who underwent primary cranioplasty procedure with a modified technique between January 2011 and December 2015 at a high-volume head and neck oncologic reconstructive practice was conducted; data analysis was also performed during that period. After several years of experience with traditional cranioplasty maneuvers, the modified technique has evolved to incorporate both autologous bone grafts and alloplastic materials in the formation of a shapeable on-lay material. Data were collected on demographics, need for cranioplasty, materials used, outcomes, and risk factors. MAIN OUTCOMES AND MEASURES: Rates of infection, hematoma, flap loss or resorption, cerebrospinal fluid leak, hardware exposure or malfunction, and repeated reconstruction. RESULTS: Of the 26 patients, 21 (81%) were men; mean (SD) age was 65.8 (14.3) years. Eight (31%) patients had a history of diabetes, 4 (15%) patients were receiving immunosuppressive drugs, and 5 (19%) patients were active smokers at the time of surgery. Neoplasia was the most common cause of the calvarial defect seen, responsible for 20 of 28 (71%) operative defects and necessitated procedures. All but 1 patient achieved successful mineralization following primary cranioplasty with the modified technique; this success was verified based on physical examination and follow-up imaging. Complications were rare and involved only 3 patients who developed postoperative infection; 1 (4%) of these patients lost the integrity of the cranioplasty. Thus, the rate of infection was 11% and loss rate was 4%. Preoperative and postoperative radiotherapy appeared to have no bearing on graft survival. CONCLUSIONS AND RELEVANCE: The results using a unique technique for incorporating both biologic autologous bone and nonbiologic allograft materials for defect coverage in cranioplasty are favorable, with satisfactory aesthetic outcomes and limited postoperative complications. LEVEL OF EVIDENCE: 4.

Lip and perioral trauma.

The management of perioral injuries is a complex topic that must take into consideration the unique anatomy, histology, and function of the lips to best restore form and function of the mouth after injury. Basic reconstructive principles include three-layered closure for full-thickness lip lacerations. Additionally, special care is needed to ensure an aesthetic repair of the cosmetically complex and important vermillion border, philtrum, and Cupid's bow. Infraorbital and mental nerve blocks provide lip anesthesia for laceration repair without distorting crucial aesthetic landmarks. Prophylactic antibiotics are usually indicated in perioral injuries due to wound contamination with saliva. Perioral burn management is controversial; however, most lip burns can first be managed conservatively. Splinting, plasties, and other reconstructive options are available after secondary healing of perioral burns. Hypertrophic scars are common in the perioral area after trauma. The mainstays of treatment for hypertrophic scars on the lips are silicone elastomer sheeting and intralesional steroid injections. For large perioral defects, a myriad of reconstructive options are available, ranging from primary closure, cross-lip flaps, and local tissue transfer, to free tissue transfers such as radial forearm free flaps, innervated gracilis free flaps, anterolateral thigh free flaps, and osteocutaneous free flaps.

Temporalis muscle flap for reconstruction of skull base defects.

BACKGROUND: The temporalis muscle flap (TMF) is a valuable reconstructive technique utilized in a variety of challenging defects. However, its use for repair of skull base defects is less commonly reported. METHODS: A retrospective chart review was conducted for 35 patients who underwent reconstruction of skull base defects between March 1999 and July 2006 at a tertiary referral hospital. Patients with skull base defects after trauma or extirpative surgery underwent reconstruction with a TMF. The measured outcomes were as follows: defect size/location, need for additional flaps, bone necrosis, hardware exposure, dehiscence, cerebrospinal fluid (CSF) leak, and meningitis. RESULTS: Forty-two patients underwent reconstruction with a TMF, and 35/42 patient records were available for review. No flap failures, 1 transient CSF leak, 3 hardware exposures distant from the temporalis recipient site, and 3 hydroxyapatite cement infections or foreign body reaction were observed. CONCLUSION: The TMF represents a versatile reconstructive technique employed with minimal morbidity and a low complication rate to repair defects of the skull base.

Risk factors predicting aspiration after free flap reconstruction of oral cavity and oropharyngeal defects.

OBJECTIVE: To determine risk factors predicting early postoperative aspiration in patients after microvascular free flap reconstruction of oral cavity and oropharyngeal defects. DESIGN: Retrospective analysis. SETTING: Academic tertiary care referral medical center. PATIENTS: The study included 100 patients who underwent resection of oral cavity or oropharyngeal tumors with immediate free flap reconstruction of the defect. MAIN OUTCOME MEASURES: Dysphagia severity was assessed by modified barium swallow study performed within 90 days after surgery to determine the presence or absence of tracheal aspiration. Aspiration risk factors analyzed included age; sex; tumor T and N stage; comorbidity level (American Society of Anesthesiologists classification); preoperative swallowing function; history of tobacco use; surgical approach used for tumor resection; defect classification; type of free flap; history of radiation therapy, surgery, and/or chemotherapy; and surgical defect classification. RESULTS: The following risk factors were significant predictors of postoperative aspiration on univariate analysis: prior radiation therapy (P < .001), tongue base resection classification (P = .001), tumor N stage (P < .001), hypoglossal nerve sacrifice (P = .004), and presence of a mandibular osteotomy (P = .01). On multivariate analysis, only a history of radiation therapy (P = .002) and tongue base resection (P = .008) remained statistically significant predictors of aspiration. CONCLUSION: Patients with resection of more than half of the tongue base and patients with a history of radiation therapy are at high risk of having early postoperative aspiration after free flap reconstruction.

The utility of the temporalis muscle flap for oropharyngeal, base of tongue, and nasopharyngeal reconstruction.

OBJECTIVE: To determine the efficacy of temporalis muscle flap reconstruction of various defects of the oropharynx, nasopharynx, and base of tongue. STUDY DESIGN: Retrospective chart review of a consecutive series of 24 patients who underwent a total of 26 temporalis flaps (2 bilateral) by the senior author (Y.D.) from September 1997 to August 2003 for reconstruction of defects of the oropharynx, nasopharynx, and base of tongue. METHODS: Variables and outcomes that were examined included defect location, size, adjunctive therapy, complications, and ability to tolerate oral intake at follow-up. RESULTS: There was no evidence of flap failure in our series of patients. There were 2 cases of minor flap loss related to early prosthetic rehabilitation. Two cases of transient frontal nerve paralysis were noted. A 30.8% rate of complication (all minor) was noted in this study. At a mean follow-up of 12 months, 54.2% of patients were tolerating a full diet, 37.5% were tolerating most of their nutrition by mouth, and 8.3% were g-tube dependent. CONCLUSION: The temporalis muscle flap represents an excellent alternative in reconstruction of otherwise difficult-to-reconstruct defects of the nasopharynx, oropharynx, and base of tongue. Donor site aesthetics are well accepted by patients with primary hydroxyapatite cement cranioplasty with or without secondary lipotransfer.

The versatile extended pericranial flap for closure of skull base defects.

OBJECTIVE: We sought to demonstrate the technical aspects of the extended pericranial flap and its versatility in reconstruction of a variety of skull base defects. STUDY DESIGN: We conducted a retrospective chart review of 32 patients who underwent reconstruction of skull-base defects with an extended pericranial flap by the senior author (Y.D.) from September 1997 to July 2003. METHODS: Patients with skull base defects after trauma or extirpative surgery were reconstructed with either a lateral- or an anterior-based vascularized extended pericranial flap. Variables and outcomes measured included: the size and anatomical location of the defect, need for other flaps, preoperative and/or postoperative radiation therapy and/or chemotherapy, bone flap necrosis, hardware exposure, wound dehiscence, postoperative cerebrospinal fluid (CSF) leak, and meningitis. RESULTS: There was no evidence of flap failure, 2 cases of transient (3 to 4 days) CSF leak without resultant meningitis, 3 patients with hardware exposure, and 2 patients with hydroxyapatite infection. The 2 transient cases of CSF leak both resolved without further surgical intervention or the placement of a lumbar drain. CONCLUSION: Both the lateral and anteriorly based extended pericranial flaps are reliable and versatile flaps associated with minimal morbidity and a low rate of complications when used to reconstruct defects of the anterolateral skull base.

Lipotransfer as an adjunct in head and neck reconstruction.

OBJECTIVES: To present our technique of lipotransfer and to evaluate a single center's experience in the use of lipotransfer as an adjunct to head and neck reconstruction. STUDY DESIGN: A retrospective review of all patients undergoing lipotransfer over a 5-year period by the senior author was undertaken. A total of 23 patients with a minimum follow-up of 1 year were available for analysis. METHODS: Patient records were retrospectively reviewed to assess functional (in the case of palate augmentation) and esthetic outcomes. RESULTS: Twenty-three patients undergoing lipotransfer as part of their reconstructive effort included (1) eight patients undergoing temporal fossa augmentation following temporalis muscle flap reconstruction for extirpative skull base surgery, (2) six patients undergoing facial defect augmentation following traumatic atrophy, (3) three patients undergoing palatal augmentation for correction of velopharyngeal insufficiency, and (4) six patients undergoing soft tissue augmentation following flap reconstruction of the face. Twenty of the 23 patients had excellent maintenance of graft volume. An adequately vascularized recipient bed appears to be an important factor in determining ultimate graft survival using our technique. CONCLUSIONS: Lipotransfer of the head and neck represents a simple, effective adjunctive technique providing for large amounts of readily available, well-tolerated soft tissue filler material. Patient selection is important, specifically in regard to determining that there is adequate vascularity of the recipient bed.

The cervicodeltopectoral flap for single-stage resurfacing of anterolateral defects of the face and neck.

OBJECTIVE: To evaluate prospectively the feasibility and utility of adding a cervical extension to the standard deltopectoral flap. We postulated that this cervicodeltopectoral (CDP) flap will allow for single-stage reconstruction of large defects of the anterolateral face and neck. METHODS: As is the case with the deltopectoral flap, the CDP flap is based on the perforating branches of the internal mammary artery. However, the superior and posterior limbs of the CDP flap are not limited by the clavicle and the deltoid muscle. Instead, they extend in a subcutaneous tissue plane to the margins of the neck or facial defect and transfer the entire intervening skin bridge with the deltopectoral flap. RESULTS: Eighteen patients underwent closure of complex cutaneous defects of the face and neck with the CDP flap. We found no evidence of flap loss in any of these patients. Twelve patients had received preoperative radiation therapy encompassing the cervical extension of the CDP flap. No evidence of adverse healing was noted in this subset of patients. CONCLUSIONS: The CDP flap may represent an alternative in the surgical treatment of various cutaneous defects of the face and neck. It allows for single-stage, reliable reconstruction of these defects. The transfer of intervening cervical skin in conjunction with the deltopectoral flap provides for a more aesthetically pleasing reconstruction, as skin immediately adjacent to the defect is more closely related to the excised skin in terms of color and texture.