Adding insult to injury: Neck exploration for penetrating pediatric neck trauma

ASSOCIATION FOR ACADEMIC SURGERY AND SOCIETY OF UNIVERSITY SURGEONS—ABSTRACTS SION IN NEUROBLASTOMA CELLS. J. Qiao, J. Kang, I. A. Titilope, K. L. O’Connor, B. Evers, D. H. Chung; The University of Texas Medical Branch, Galveston, TX. Gastrin-releasing peptide (GRP) acts as an autocrine growth factor for neuroblastoma cells. Overexpression of the GRP receptor (GRPR), which increases binding capacity for its ligand GRP, has been shown to stimulate cell growth; however, the exact role of GRP on tumor invasion/metastatic properties is unknown. Integrin is a heterodimer composed of ␣- and ␤-subunits; 24 integrin isoforms exist, from different pairings among 18 ␣- and 8 ␤-subunits. Integrins bind to components of extracellular matrix (ECM) such as collagen, fibronectin, and laminin to mediate cell adhesion, spread, or migration. The purpose of our study was to investigate the effect of GRP on integrin expression in neuroblastoma cells. Methods: To determine the effects of autocrine growth factor, GRP, on integrin expression, human neuroblastoma cell line, SK-N-SH, was stably transfected with pEGFP (control vector) and pEGFP-GRP-R plasmids. We then performed a metastasis specific gene array (SuperArray) assay. The expression of ECM receptor integrins was analyzed by Western blot analysis. The expression of cell membrane integrin protein levels was determined by fluorescence-activated cell sorter analysis (FACS). Results: Human neuroblastoma cells overexpressing GRP-R, which we had previously shown to increase GRP binding capacity, demonstrated marked changes in their cell morphology; cells appeared flat and more adhesive to culture plates. Gene array showed increased expression of integrins ␤1, ␣2, and ␣3 when compared to control cells. Consistent with these data, Western blot analysis showed increased protein expression of integrins ␤1, ␣2, and ␣3 in GRP-R overexpressing cells. These findings were further confirmed by FACS, where GRP-R overexpression resulted in increased expression of functional cell surface membrane integrins ␤1, ␣2, and ␣3. Conclusions: GRP-R overexpression resulted in enhanced mRNA and protein expression of integrins, suggesting that GRP-induced neuroblastoma cell proliferation may also enhance factors responsible for tumor invasion/metastatic potential. A better understanding of this process may allow us to develop novel therapy targeted at inhibiting GRP-induced neuroblastoma cell proliferation and metastasis. 335. PHOSPHATIDYLINOSITOL 3-KINASE/AKT PATHWAY IS INVOLVED IN RETINOIC ACID-INDUCED NEUROBLASTOMA CELL DIFFERENTIATION. J. Qiao, J. Kang, T. A. Ishola,, B. Evers, D. H. Chung; The University of Texas Medical Branch, Galveston, TX. The overall prognosis for pediatric patients with neuroblastoma remains poor, largely due to aggressive undifferentiated tumor behavior and high recurrence rate. Recently, much focus has been directed to the use of differentiating agents, such as retinoid acid (RA), for the treatment of aggressive neuroblastomas; the cellular mechanisms involved in this process are not clearly defined. The phosphatidylinositol 3-kinase (PI3-K) is an important signaling pathway for cell survival and proliferation; however, a little is known about its role in cellular differentiation. Therefore, the purpose of this study was to determine whether PI3-K pathway plays a crucial role in the RA-induced differentiation of neuroblastoma cells. Methods: Human neuroblastoma cell lines (SK-N-SH and BE(2)-C) were treated with RA (5 ␮M) for 24 h to induce differentiation. Cell differentiation was observed with light microscopy. To determine whether the PI3-K pathway is involved in this process, cells were treated with RA with or without LY294002 (20 ␮M), a specific inhibitor of PI3-K. The phosphorylation of Akt, a downstream effector for PI3-K, was measured by Western blot analysis. The effects of RA on cell cycle progression were assessed by flow cytometry. Cell survival and DNA fragmentation were analyzed by ELISA. Results: Treatment with RA resulted in differentiation of human neuroblastoma cells as demonstrated by marked neurite-like extensions when com-

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pared to cells treated with vehicle alone (control); this effect was blocked by LY294002 treatment. RA treatment also increased Akt phosphorylation; this increase was attenuated with LY294002. Additionally, cells were arrested in the G1 phase and the expression of cyclin dependent kinase inhibitors p21Cip and p27Kip were significantly increased with RA treatment; this induction was prevented by LY294002. RA treatment also resulted in an approximately 50% increase in cell survival and 60% decrease in DNA fragmentation. Conclusions: Our results demonstrate that RA-induced neuroblastoma cell differentiation occurs via activation of the PI3-K pathway. Moreover, RA-induced differentiation appears to involve regulation of cell cycle arrest. RA-induced differentiation is also associated with enhanced cell survival and increased apoptosis in neuroblastoma cells. These findings suggest that PI3-K is a critical signaling pathway involved in RA-induced neuroblastoma differentiation and may provide insights into developing novel therapeutic strategies targeted at key cellular signaling. 336. ADDING INSULT TO INJURY: NECK EXPLORATION FOR PENETRATING PEDIATRIC NECK TRAUMA. Stringer RA, Roberson R; University of Mississippi Penetrating neck injuries are uncommon in children, and management involves mandatory exploration of the neck. This reslts in a number of unnecessary operations. Adult experience is moving towards selective exploration. Methods: A retrospective review was performed on all trauma patients presenting over the past 10 years. After IRB approval, pediatric patients with penetrating neck injury were selected and data was collected and analyzed. Results: A total of 38 patients were identified over the study period. The average age was 13 years, and 56% cases were male. A large proportion (75%) were African-American. Over half (63%) were from projectiles, including 55% gun shot wounds, which tended to be in older children, while 5 dog bites were noted as a predominant cause in the younger ones. Six patients underwent exploration without preoperative imaging due to penetration of the platysma. Four of these were non therapeutic in nature. Eighteen patients underwent imaging due to penetration out of which 16 avoided an exploration. CT scan was the most common imaging modality (68%), followed by angiography and barium swallows. Thirteen cases did not have imaging other than plain radiographs and also did not have an exploration. The mean injury severity score was 11. The length of stay was longer in the patients who underwent exploration. One patient died from concomitant injury to the thorax. Conclusions: This is the largest series of penetrating cervical injuries in children. Mandatory exploration of the neck should not be performed unless clinically indicated. Preoperative imaging should be used liberally to reduce non therapeutic explorations and morbidity. 337. DOES SURGEONS’ PREFERENCE PREDICT TIME TO FEEDING IN PERFORATED APPENDICITIS? Walker A, Henry MC, Silverman BL, Gollin G, Islam S, Sylvester K, Moss RL; Yale University School of Medicine Background: We sought to identify whether surgeons’ preference, in comparison to clinical factors, influenced the time to sustained oral intake (SOI) in children treated for perforated appendicitis. Methods: Historical cohort study of children ages 1-18 with perforated appendicitis from 1998-2003 at 4 tertiary care children’s hospitals. 17 factors analyzed as predictors of time to SOI using one-way ANOVA and t-tests. Survival analyses evaluated the effect of surgeons’ preference on time to SOI. Results: 279 cases. 10 surgeons contributed a median of 22 cases (12-62). 9% developed a complication by day of SOI. The median day of SOI was post-op day 3. 8 factors: surgeons’ preference, operation type, perforation noted in OR, complication, and status of fever, stool, vomiting, and opiate use, were associated with time to SOI at p⬍0.15. In the adjusted multivariate survival analysis, surgeons’ preference was not a sig-