A Quantitative Evaluation of Functional Recovery after Traumatic Lower Extremity Salvage.

INTRODUCTION: Soft tissue reconstruction is a routine component of lower extremity trauma care and focus is increasingly being directed towards understanding functional outcomes. This study aims to quantify functional recovery and identify variables associated with functional outcomes of patients who undergo traumatic limb salvage. METHODS: A retrospective review was performed of patients with lower extremity traumatic injuries requiring vascularized soft tissue reconstruction at a Level 1 trauma center between July 2007-December 2015. Postoperatively, patients were administered the 36-Item Short Form Health Survey Version 2 (SF-36v2) and the Lower Extremity Functional Scale (LEFS) questionnaires by telephone. Demographics, perioperative variables, and postoperative outcomes were analyzed by univariate and bivariate analysis. RESULTS: Forty-two patients with 42 flaps and a mean of 12.7 months follow up were included in the study. Limb salvage was successful in 38 patients (90.5%). Patients ≥ 40 years old had significantly worse SF-36v2 scores in physical functioning (P ≤0.01) and mental health (P ≤0.05) than their younger counterparts. Patients who had pre-existing hypertension demonstrated significantly lower physical functioning (P ≤0.01). Role limitation due to emotional health was significantly lower in patients who were female (P ≤0.01) or required revision surgery (P ≤0.01). The mean LEFS score was 37.7 ± 18.5. CONCLUSIONS: Patients exhibited poor functional outcomes following major limb trauma with attempted limb salvage based on two validated patient reported outcomes measures (PROMs). Patient characteristics should be considered in evaluating candidates for reconstruction to optimize outcomes and to effectively counsel patients on their functional prognosis.

Functional Outcomes After Sauve-Kapandji Arthrodesis.

PURPOSE: The Sauve-Kapandji procedure (SK) combines a distal radioulnar joint (DRUJ) arthrodesis with the creation of an ulnar pseudarthrosis for the salvage of DRUJ instability or arthritis. Despite several published case series, there are limited data on postoperative functional outcomes. This study evaluates patient-reported outcomes of SK using a validated functional outcomes scale. METHODS: We performed a retrospective review of patients who underwent SK in 2 health care systems over 10 years (2008-2018). Preoperative and postoperative range of motion, Quick-Disabilities of the Arm, Shoulder, and Hand (QuickDASH) scores, and wrist plain film radiographic measurements were recorded. Preoperative and postoperative outcomes analyses and subgroup comparisons were performed. RESULTS: We included 57 patients in the study. Surgical indications included posttraumatic DRUJ arthritis (n = 35), rheumatoid arthritis (n = 10), degenerative DRUJ arthritis (n = 7), Madelung deformity (n = 3), psoriatic arthritis (n = 1), and giant cell tumor of bone (n = 1). During the first postoperative year, QuickDASH scores decreased from a mean of 52 before surgery to 28 at 12 months. The QuickDASH scores at final follow-up demonstrated significant improvement in patients with osteoarthritis and inflammatory arthritis. Supination significantly improved after surgery, from 48° to 74°, whereas wrist flexion, wrist extension, and pronation remained unchanged. Radiographically, significant postoperative decreases were seen in ulnar variance and McMurtry's translation index. The postoperative complication rate was 21%, including revision osteotomy in 4 patients (7.0%) and hardware removal in 4 patients (7.0%). No DRUJ nonunions were seen. CONCLUSIONS: The Sauve-Kapandji procedure for DRUJ salvage significantly improved patient-reported outcomes after 1 year and significantly improved supination. Similar functional improvements after SK were seen in both osteoarthritis and inflammatory arthritis. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The Efficacy of Negative Pressure Wound Therapy and Antibiotic Beads in Lower Extremity Salvage.

BACKGROUND: Antibiotic beads and negative pressure wound therapy (NPWT) represent two methods of wound management used during staged debridement in the post-trauma limb salvage pathway. The efficacy of NPWT and antibiotic beads in preventing infection remains unclear. METHODS: This study is a retrospective review of patients with traumatic lower extremity open fractures who received NPWT and/or antibiotic beads before soft tissue reconstruction at an urban level 1 trauma center between August 2007 and December 2015. Patients with wound infections before application of NPWT and/or antibiotic beads were excluded. RESULTS: In 73 lower extremities requiring soft tissue coverage, 46 received antibiotic beads and 48 received NPWT. Overall infection rate was 15.1%. Use of antibiotic beads was associated with a decreased risk of infection (6.4% versus 30.7%; P = 0.01). Use of NPWT was associated with an increased risk of one or more complications (45.7% versus 4.2%; P = 0.001). The development of infection was associated with a greater period of time between application of antibiotic beads (22 ± 13 versus 12 ± 6 d, P = 0.01) or NPWT (23 ± 15 versus 10 ± 11 d, P = 0.004) and soft tissue coverage. Overall limb salvage rate was 95.9%; secondary amputation was associated with development of infection (P = 0.001) but not with use of NPWT or antibiotic beads. CONCLUSIONS: Antibiotic beads may prevent infections in patients awaiting soft tissue coverage of wounds. NPWT may contribute to a greater rate of complication. Limb salvage was successful in most cases regardless of method of wound management.

Functional outcomes of traumatic lower extremity reconstruction.

BACKGROUND: Lower extremity trauma accounts for over 300,000 injuries annually. While soft tissue transfer is a well-accepted practice for open fracture coverage, functional outcomes remain unclear. HYPOTHESIS: This study investigates functional outcomes following soft tissue reconstruction for open tibial fractures. MATERIALS AND METHODS: A retrospective review of a prospectively maintained database of open tibia fractures requiring soft tissue reconstruction was performed at an urban level 1 trauma center between October 2013 and March 2015. OUTCOMES: were evaluated using Pearson's chi square test with significant p value < 0.05. RESULTS: In 30 patients, fractures were graded Gustilo-Anderson type I (3.3%), 30% type II, 3.3% type IIIa, 53.3% type IIIb, and 10% type IIIc. Fixation was 56.7% plate and screw, 20% intramedullary nail, and 16.7% external fixator. Definitive closure was achieved in 43.3% through local rotational flap (38.5% gastrocnemius, 61.5% soleus), and in 56.7% by free tissue transfer (29.4% latissimus, 23.5% rectus, 17.6% ALT, 17.6% gracilis). In 10 patients, 70% returned to full ambulation, 30% required an assistance device, and 50% achieved union in 6 months. Local flap use was predictive of ambulation at discharge. DISCUSSION: Following lower extremity fracture, 70% of patients returned to pre-injury function. Use of a local tissue flap was associated with early ambulation.

A Systematic Review of Prognostic Factors for Sensory Recovery After Digital Nerve Reconstruction.

BACKGROUND: Successful digital nerve repair is crucial in preventing painful neuroma formation and restoring sensory function after traumatic hand injury. The purpose of this study is to identify prognostic factors affecting sensory recovery following digital nerve reconstruction. METHODS: A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines including studies reporting patients 18 years and older, greater than 10 reconstructed digital nerves, and greater than or equal to 3 months follow-up. Studies with proximal nerve injuries in the same distribution or inadequate sensory data were excluded. Included studies were evaluated by methodological index for nonrandomized studies score. Possible predictors were examined using the t test and 1-way analysis of variance with α ≤ 0.05. RESULTS: Twenty-five studies met the inclusion criteria, consisting of 818 surgically reconstructed digital nerves (mean age, 38 years; 78% male) with a mean ± SD defect length of 1.5 ± 0.5 cm. Mean follow-up time was 22 months. Fifty-six percent of patients presented with concomitant injuries to tendons (31%) and the digital artery (13%). Mean ± SD time to surgical repair was 36 ± 73.8 days. Reconstructive techniques included 35% end-to-end primary neurorrhaphy, 31% nerve grafts, and 11% synthetic conduits. Postoperatively, 81% of the patients demonstrated sensory recovery of S3+/S4, with 45% complaining of hyperesthesia. Nerve reconstructions performed within 15 days of injury had significantly better static 2-point discrimination than delayed procedures (P = 0.02). Static 2-point discrimination measurements were also significantly better for shorter defect lengths (<1.3 cm, P = 0.05). No significant functional differences were found across age, follow-up time, injured digit or side, nor reconstructive technique. CONCLUSIONS: Digital nerve reconstruction has good to excellent sensory recovery in up to 81% of patients with improved results in nerve gaps less than 1.3 cm. Performing the reconstruction within 15 days of injury is also correlated with improved sensory recovery.

Combined Direct and Indirect Cerebral Revascularization Using Local and Flow-Through Flaps.

BACKGROUND: Extracranial-intracranial bypass is indicated in ischemic disease such as moyamoya, certain intracranial aneurysms, and other complex neurovascular diseases. In this article, we present our series of local and flow-through flaps for cerebral revascularization as an additional tool to provide direct and indirect revascularization and/or soft tissue coverage. METHODS: A retrospective review of a prospectively maintained database was performed identifying nine patients. Ten direct arterial bypass procedures with nine indirect revascularization and/or soft tissue reconstruction were performed. RESULTS: Indications for arterial bypass included intracranial aneurysm (n = 2) and moyamoya disease (n = 8). Indications for soft tissue transfer included infected cranioplasty (one) and indirect cerebral revascularization (eight). Four flow-through flaps and five pedicled flaps were used including a flow-through radial forearm fasciocutaneous flap (one), flow-through radial forearm fascial flaps (three), and pedicled temporoparietal fascial (TPF) flaps with distal end anastomosis (five). The superficial temporal vessels (seven) and facial vessels (two) were used as the vascular inflow. Arterial bypass was established into the middle cerebral artery (six) and anterior communicating artery (three). There were no intraoperative complications. All flaps survived with no donor-site complications. In one case of flow-through TPF flap, the direct graft failed, but the indirect flap remained vascularized. CONCLUSION: Local and flow-through flaps can improve combined direct and indirect revascularization and provide soft tissue reconstruction. Minimal morbidity has been encountered in early outcomes though long-term results remain under investigation for these combined neurosurgery and plastic surgery procedures. LEVEL OF EVIDENCE: The level of evidence is IV.

Investigation Into the Optimal Number of Intercostal Nerve Transfers for Musculocutaneous Nerve Reinnervation: A Systematic Review.

BACKGROUND: The purpose of this study was to systematically review outcomes following intercostal nerve (ICN) transfer for restoration of elbow flexion, with a focus on identifying the optimal number of nerve transfers. METHODS: A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to identify studies describing ICN transfers to the musculocutaneous nerve (MCN) for traumatic brachial plexus injuries in patients 16 years or older. Demographics were recorded, including age, time to operation, and level of brachial plexus injury. Muscle strength was scored based upon the British Medical Research Council scale. RESULTS: Twelve studies met inclusion criteria for a total of 196 patients. Either 2 (n = 113), 3 (n = 69), or 4 (n = 11) ICNs were transferred to the MCN in each patient. The groups were similar with regard to patient demographics. Elbow flexion ≥M3 was achieved in 71.3% (95% confidence interval [CI], 61.1%-79.7%) of patients with 2 ICNs, 67.7% (95% CI, 55.3%-78.0%) of patients with 3 ICNs, and 77.0% (95% CI, 44.9%-93.2%) of patients with 4 ICNs ( P = .79). Elbow flexion ≥M4 was achieved in 51.1% (95% CI, 37.4%-64.6%) of patients with 2 ICNs, 42.1% (95% CI, 29.5%-55.9%) of patients with 3 ICNs, and 48.4% (95% CI, 19.2%-78.8%) of patients with 4 ICNs ( P = .66). CONCLUSIONS: Previous reports have described 2.5 times increased morbidity with each additional ICN harvest. Based on the equivalent strength of elbow flexion irrespective of the number of nerves transferred, 2 ICNs are recommended to the MCN to avoid further donor-site morbidity.

Soft tissue reconstruction and salvage of infected fixation hardware in lower extremity trauma.

BACKGROUND: Tibial fracture management may be complicated by infection of internal fixation hardware (iIFH) resulting in increased morbidity and amputation rate. When iIFH removal is not possible, salvage of the lower extremity is attempted through debridement, antibiotics, and vascularized soft tissue coverage. This study investigates lower extremity salvage with retention of iIFH. METHODS: Demographics, outcomes, and bacterial speciation in patients with tibial fractures at a level 1 trauma center from 2007 to 2014 were reviewed. The primary outcome was infection suppression, while secondary outcomes included limb salvage, amputation, and osseous union. RESULTS: Twenty-five patients underwent soft tissue reconstruction for salvage of iIFH. Average age was 41, 19 (76%) were male, average BMI 30.1 kg/m2 , 10 (40%) patients smoked. Tibial fractures were closed in 8 (32%), Gustilo-Anderson grade I in 1 (4%), II in 8 (32%), IIIb in 5 (20%), and IIIc in 1 (4%). Staphylococcus was most commonly cultured with 11 (44%) demonstrating methicillin-resistance. Soft tissue reconstruction was performed by local flap in 15 (60%) and free flap in 10 (40%). At an average of 16.1 months, 19 (76%) hardware salvage patients demonstrated clinical suppression of infection, 11 of 19 (57.9%) patients had bony union, and 24 (96%) maintained a salvaged limb. One patient was amputated for recurrent infection. CONCLUSIONS: Following complex, infected tibial fractures, salvage of the lower extremity may be attempted even when iIFH cannot be removed. Thorough debridement, antibiotics, and vascularized soft tissue may suppress infection long enough to facilitate osseous union and subsequent removal of iIFH.

Redefining the Anatomic Boundaries for Safe Dissection of the Skin Paddle in a Gracilis Myofasciocutaneous Free Flap: An Indocyanine Green Cadaveric Injection Study.

The gracilis free flap remains a versatile option in the reconstructive ladder. The flap itself can be harvested with or without a skin paddle. The gracilis myocutaneous free flap, however, is known for partial skin flap necrosis, especially in the distal one-third of the skin island. The gracilis myofasciocutaneous flap has been previously described as a technique to improve perfusion to the skin by harvesting surrounding deep fascia in a pedicled flap. However, limitations to this study required injection of multiple pedicles to demonstrate its perfusion. We demonstrate a novel technique using a cadaveric model that shows perfusion through injection via a single dominant pedicle (medial circumflex) with a large cutaneous paddle (average 770 cm2) with included deep fascia, using indocyanine green and near-infrared imaging. For comparison, we are also able to confirm the lack of perfusion to the distal cutaneous paddle when the fascia is not harvested, correlating with previous findings and ink injection studies. This novel technique is versatile, relatively inexpensive, and can demonstrate perfusion patterns via perforasomes that were otherwise not possible from previous techniques. Additionally, real-time imaging is possible, helping to elucidate the sequence of flow into the flap and potentially predict areas of flap necrosis.

Preoperative surgical rehearsal using cadaveric fresh tissue surgical simulation increases resident operative confidence.

BACKGROUND: Rehearsal is an essential part of mastering any technical skill. The efficacy of surgical rehearsal is currently limited by low fidelity simulation models. Fresh cadaver models, however, offer maximal surgical simulation. We hypothesize that preoperative surgical rehearsal using fresh tissue surgical simulation will improve resident confidence and serve as an important adjunct to current training methods. METHODS: Preoperative rehearsal of surgical procedures was performed by plastic surgery residents using fresh cadavers in a simulated operative environment. Rehearsal was designed to mimic the clinical operation, complete with a surgical technician to assist. A retrospective, web-based survey was used to assess resident perception of pre- and post-procedure confidence, preparation, technique, speed, safety, and anatomical knowledge on a 5-point scale (1= not confident, 5= very confident). RESULTS: Twenty-six rehearsals were performed by 9 residents (PGY 1-7) an average of 4.7±2.1 days prior to performance of the scheduled operation. Surveys demonstrated a median pre-simulation confidence score of 2 and a post-rehearsal score of 4 (P<0.01). The perceived improvement in confidence and performance was greatest when simulation was performed within 3 days of the scheduled case. All residents felt that cadaveric simulation was better than standard preparation methods of self-directed reading or discussion with other surgeons. All residents believed that their technique, speed, safety, and anatomical knowledge improved as a result of simulation. CONCLUSIONS: Fresh tissue-based preoperative surgical rehearsal was effectively implemented in the residency program. Resident confidence and perception of technique improved. Survey results suggest that cadaveric simulation is beneficial for all levels of residents. We believe that implementation of preoperative surgical rehearsal is an effective adjunct to surgical training at all skill levels in the current environment of decreased work hours.

Outcomes of Soft Tissue Reconstruction for Traumatic Lower Extremity Fractures with Compromised Vascularity.

Traumatic lower extremity fractures with compromised arterial flow are limb-threatening injuries. A retrospective review of 158 lower extremities with traumatic fractures, including 26 extremities with arterial injuries, was performed to determine the effects of vascular compromise on flap survival, successful limb salvage and complication rates. Patients with arterial injuries had a larger average flap surface area (255.1 vs 144.6 cm2, P = 0.02) and a greater number of operations (4.7 vs 3.8, P = 0.01) than patients without vascular compromise. Patients presenting with vascular injury were also more likely to require fasciotomy [odds ratio (OR): 6.5, confidence interval (CI): 2.3-18.2] and to have a nerve deficit (OR: 16.6, CI: 3.9-70.0), fracture of the distal third of the leg (OR: 2.9, CI: 1.15-7.1) and intracranial hemorrhage (OR: 3.84, CI: 1.1-12.9). After soft tissue reconstruction, patients with arterial injuries had a higher rate of amputation (OR: 8.5, CI: 1.3-53.6) and flap failure requiring a return to the operating room (OR: 4.5, CI: 1.5-13.2). Arterial injury did not correlate with infection or overall complication rate. In conclusion, arterial injuries resulted in significant complications for patients with lower extremity fractures requiring flap coverage, although limb salvage was still effective in most cases.

Optimizing Outcomes following Total and Subtotal Tongue Reconstruction: A Systematic Review of the Contemporary Literature.

Background More than 45,000 Americans are diagnosed with oropharyngeal cancer annually and multimodal treatment often requires wide excision, lymphadenectomy, chemotherapy, and radiation. Total and subtotal lingual resection severely impairs speech, swallow, and quality of life (QoL). This study investigates functional outcomes and QoL following subtotal and total tongue resection with free tissue transfer reconstruction. Materials and Methods A systematic review of the English language literature was performed using PubMed, Ovid, Embase, and Cochrane databases based on predetermined inclusion/exclusion criteria. Included studies were reviewed for surgical technique, adjuvant treatment, surgical and functional outcomes, and QoL. Results From an initial search yield of 1,467 articles, 22 studies were included for final analysis. Speech intelligibility was correlated with the volume and degree of protuberance of the neotongue. Adjuvant therapy (radiation) and large tumor size were associated with worse speech and swallow recovery. At 1 year follow-up, despite 14 to 20% rates of silent aspiration, 82 to 97% of patients resumed oral feeding. Neurotized flaps have been demonstrated to improve flap sensation but have not yet demonstrated any significant impact on speech or swallow recovery. Finally, many patients continue to experience pain after surgery, but patient motivation, family support with physician, and speech therapist follow-up are associated with improved QoL scores. Conclusion Tongue reconstruction is dictated by the amount of soft tissue resection. Taking into consideration the most common factors involved after tongue resection and reconstruction, further studies should focus on more objective measurements to offer solutions and maximize final outcomes.

Patient and Surgical Factors Contributing to Perioperative Infection in Complex Lower Extremity Trauma.

Infections in the traumatized lower extremity are a significant source of morbidity and expense. Outcomes after vascularized soft tissue reconstruction were analyzed to determine impact on infection rates. A retrospective review of a prospectively maintained database was performed, including 114 trauma patients requiring soft tissue reconstruction of lower extremity injuries at an urban Level I tertiary referral center from 2008 to 2015. Patient characteristics and perioperative outcomes were analyzed. After trauma, 39 (34.2%) patients developed wound infections, of which 74.4 per cent of infections occurred before soft tissue coverage. Isolated lower extremity injury yielded a 4-fold increase in the incidence of infection. Infection rates doubled in patients who smoked, sustained a fall, had a proximal third of the lower leg wound, or underwent external fixation. Comorbid diabetes, underlying fracture, and wound size were not predictive of infection. Overall, there was a 97.4 per cent rate of limb salvage after soft tissue reconstruction. In patients with infection before soft tissue reconstruction, a salvage rate of 96.6 per cent was achieved. Soft tissue reconstruction in the traumatized and infected lower extremity resulted in high limb salvage success rates, demonstrating vascularized tissue transfer in lower extremity injuries is effective in treating lower extremity infection.

Delayed Presentation of a Chronic Morel-Lavallée Lesion.

Morel-Lavellée lesions are soft tissue degloving injuries resulting from shearing trauma that induces separation of the superficial and deep fascias creating a potential space that becomes filled with hemolymph. Here we present a case of a 28-year-old male presenting with a persistent Type I Morel-Lavallée lesion 2.5 years after an automobile versus pedestrian accident. These lesions can be visualized via computed tomography, plain film and ultrasound, but magnetic resonance imaging is the modality of choice for their identification and characterization.

Abdominal Bulge After Retroperitoneal Dissection: The Definitive Management Using Bone Anchored Mesh.

BACKGROUND: Abdominal bulge after retroperitoneal dissection occurs at a rate of 1% to 56%. Injury to the T11 and T12 nerves is thought to result in abdominal musculature denervation, laxity, and symptomatic abdominal bulge. This complication has become more prevalent because the retroperitoneal approach for spinal surgery has become the preferred approach in specific lumbar and thoracic cases. Current repair techniques fail to address the etiology of abdominal wall laxity, and outcomes are poorly reported. Recurrence rates in lateral abdominal bulge repair are reported between 0% and 100%, and the complication rate is nearly 25%. We present a method of bone anchored fixation of mesh for abdominal wall reinforcement after the imbrication of the atrophied musculature, resulting in the definitive treatment of abdominal bulge after retroperitoneal dissection. METHODS: A retrospective review of 4 consecutive patients who underwent bony fixation of mesh using Mitek suture anchors (De Puy, Raynham, MA) for abdominal bulge after retroperitoneal dissection between February 2013 and September 2014 was performed. The preoperative, intraoperative, and postoperative records of 4 patients were reviewed and compared. RESULTS: There were no reported early recurrences and no perioperative morbidity or mortality related to the operation. Average follow-up was 12.8 months (range, 6-26 months); operative time, 157 minutes; postoperative length of stay, 3.5 days; and estimated blood loss was 50 mL. CONCLUSIONS: Reinforcement of the myofascial repair using bone anchored fixation of mesh represents a novel approach for the treatment of abdominal bulge after retroperitoneal dissection. Results demonstrate safety and no early recurrence.

Emerging trends in social media and plastic surgery.

Social media has increasingly changed the landscape of medicine and surgery and is rapidly expanding its influence in most peoples' lives. The average person spends nearly 2 hours per day using social media, consuming information about everything from family updates to entertainment news to presidential elections. The concentration of consumers on social media platforms has resulted in direct medicine and medical products marketing to consumers. Similarly, social media is increasingly becoming a platform for interaction between physicians and potential patients. Some physicians have taken this opportunity to better educate patients, while allowing patients to learn more about their surgeons online. These tools can increase internet traffic online to bonafide internet sites, as well as bolster marketing for many hospitals, hospital systems, and individual doctors. It can also serve to increase knowledge about procedures and conditions through direct outreach to patients. Social media is a powerful tool which needs to be utilized wisely to avoid pitfalls.

Perfused fresh cadavers: method for application to surgical simulation.

BACKGROUND: Cadaveric dissection is the gold standard for surgical simulation because it demonstrates authentic anatomy and tissue handling. We present a perfusion technique that restores blood flow and pressure in the fresh human cadaveric model. METHODS: The femoral vessels were cannulated and perfused using a vortex centrifugal pump and a novel perfusate. The trachea was intubated and mechanically ventilated. Tissue perfusion was evaluated by direct inspection, intravascular pressure monitoring, and indocyanine green angiography. A cost analysis and survey results for 969 trainees is presented. RESULTS: A mean arterial pressure of 80 mm Hg and venous pressure of 15 mm Hg were established, resulting in dermal and microvascular perfusion. Successful pulmonary ventilation was achieved. This model has been applied to 122 cadaveric specimens over 12 months in a variety of surgical subspecialties and training levels. Total cost for establishing the perfused model was $1,262.55. Trainee confidence after use of the model increased from 2.85 to 4.20 (P < .00). CONCLUSIONS: Perfusion of fresh cadavers replicates human tissue handling, vascular anatomy, and dissection. The perfused human cadaver increases the authenticity of surgical simulation and is applicable to procedure-based specialties.

Modification of the L1-CAM carboxy-terminus in pancreatic adenocarcinoma cells.

The neural cell adhesion molecule L1 has recently been shown to be expressed in pancreatic adenocarcinoma (PDAC) cells. In this report, we demonstrate that L1 is expressed by moderately- to poorly-differentiated PDAC cells in situ, and that L1 expression is a predictor of poor patient survival. In vitro, reduced reactivity of an anti-L1 carboxy-terminus-specific antibody was observed in the more poorly differentiated fast-growing (FG) variant of the COLO357 population, versus its well-differentiated slow-growing (SG) counterpart, even though they express equivalent total L1. The carboxy-terminus of L1 mediates binding to the MAP kinase-regulating protein RanBPM and mutation of T1247/S1248 within this region attenuates the expression of malignancy associated proteins and L1-induced tumorigenicity in mice. Therefore, we reasoned that the differential epitope exposure observed might be indicative of modifications responsible for regulating these events. However, epitope mapping demonstrated that the major determinant of binding was actually N1251; mutation of T1247 and S1248, alone or together, had little effect on C20 binding. Moreover, cluster assays using CD25 ectodomain/L1 cytoplasmic domain chimeras demonstrated the N1251-dependent, RanBPM-independent stimulation of erk phosphorylation in these cells. Reactivity of this antibody also reflects the differential exposure of extracellular epitopes in these COLO357 sublines, consistent with the previous demonstration of L1 ectodomain conformation modulation by intracellular modifications. These data further support a central role for L1 in PDAC, and define a specific role for carboxy-terminal residues including N1251 in the regulation of L1 activity in PDAC cells.