Nonoperative treatment of acute appendicitis in children: A feasibility study.

PURPOSE: Nonoperative treatment of acute appendicitis appears to be feasible in adults. It is unclear whether the same is true for children. METHODS: Children 5-18 years with <48 h symptoms of acute appendicitis were offered nonoperative treatment: 2 doses of piperacillin IV, then ampicillin/clavulanate ×1 week. Treatment failure (worsening on therapy) and recurrence (after completion of therapy) were noted. Patients who declined enrollment were asked to participate as controls. Cost-utility analysis was performed using Pediatric Quality of Life Scale (PedsQL®) to calculate quality-adjusted life month (QALM) for study and control patients. RESULTS: Twenty-four patients agreed to undergo nonoperative management, and 50 acted as controls. At a mean follow-up of 14 months, three of the 24 failed on therapy, and 2/21 returned with recurrent appendicitis at 43 and 52 days, respectively. Two patients elected to undergo an interval appendectomy despite absence of symptoms. Appendectomy-free rate at one year was therefore 71% (C.I. 50-87%). No patient developed perforation or other complications. Cost-utility analysis shows a 0.007-0.03 QALM increase and a $1359 savings from $4130 to $2771 per nonoperatively treated patient. CONCLUSION: Despite occasional late recurrences, antibiotic-only treatment of early appendicitis in children is feasible, safe, cost-effective and is experienced more favorably by patients and parents.

Utility of admission serum lactate in pediatric trauma.

BACKGROUND/PURPOSE: Serum lactate measurement has a predictive value in adult trauma. To date, there has been no prospective analysis of the predictive value of admission serum lactate in pediatric trauma. METHODS: Admission serum lactate was prospectively measured over a two year period on all children under age 15 years who met trauma alert criteria at an urban Level 1 trauma center. Elevated serum lactate (>2.0 mmol/L) was correlated with Injury Severity Scores (ISS), injury types, and hospital outcomes. RESULTS: A total of 277 injured children with admission lactate measurements were evaluated. Patients with elevated lactate had higher mean ISS than those with normal lactate (12.8 vs. 5.1, p<0.01), and increased need for intubation, major procedures and ICU admission. Elevated lactate was associated with low specificity (54.4%), moderate sensitivity (86.7%) and high negative predictive value (94.5%) for detecting injury (ISS>15). Lactate measurements over 4.7 mmol/L were highly specific (95.8%) for injury. CONCLUSIONS: Elevated admission venous lactate level is associated with injury and outcomes, but lacks adequate sensitivity and specificity. Lactate over 4.7 mmol/L is strongly suggestive of severe injury, while lactate below 2.0 mmol/L is reassuring for not having injury. Lactates between 2.0 and 4.7 mmol/L remain indeterminate in predictive potential for injury or outcomes.

HIF-1α activation mediates resistance to anti-angiogenic therapy in neuroblastoma xenografts.

INTRODUCTION: The anti-tumor activity of angiogenesis inhibitors is often limited by the development of resistance to these drugs. Here we establish HIF-1α as a major factor in the development of this resistance in neuroblastoma xenografts. METHODS: Neuroblastoma xenografts were established by injecting unmodified SKNAS or NB-1691 cells (2 × 10(6) cells), or cells in which HIF-1α expression had been knocked down with shRNA, into the retroperitoneal space of SCID mice. Treatment of established tumors included bevacizumab (5mg/kg q2wk), sunitinib (40 mg/kg qd), or topotecan (0.5mg/kg qd) alone or in combination for a total of two weeks. RESULTS: NB-1691 xenografts showed no difference in relative growth in HIF-1α knockdowns compared to control tumors (73.33 ± 7.90 vs 79.94 ± 6.15, p=0.528). However, HIF-1α knockdowns demonstrated relative final volumes that were significantly lower than unmodified tumors when both were treated with bevacizumab (35.88 ± 4.24 vs 53.57 ± 6.61, p=0.0544) or sunitinib (12.46 ± 2.59 vs 36.36 ± 4.82, p=0.0024). Monotherapy of unmodified xenografts with bevacizumab, sunitinib, or topotecan was largely ineffective. Relative final volumes of NB-1691 xenografts were significantly less in cohorts treated with sunitinib+topotecan (4.78 ± 0.77 vs 39.17 ± 2.44 [sunitinib alone], p=0.011) and bevacizumab+topotecan (13.63 ± 1.55 vs 48.16 ± 9.94 [bevacizumab alone], p=0.014). CONCLUSION: Upregulation of HIF-1α appears to be a significant mechanism of resistance to antiangiogenic therapies in neuroblastoma. Suppressing HIF-1α with low-dose topotecan potentiates the effects of the antiangiogenic drugs in a mouse model.

Rapamycin increases neuroblastoma xenograft and host stromal derived osteoprotegerin inhibiting osteolytic bone disease in a bone metastasis model.

PURPOSE: Osteoprotegerin (OPG) is a decoy receptor for the Receptor of NF-κB (RANK) ligand that can inhibit osteoclastogenesis. Previous studies have suggested that Mammalian Target of Rapamycin (mTOR) inhibition upregulates OPG production. We tested the hypothesis that the mTOR inhibitor rapamycin could inhibit neuroblastoma bone metastases through its action on OPG. EXPERIMENTAL DESIGN: An orthotopic model of bone metastasis was established. Mice with established disease were subsequently treated with rapamycin (5mg/kg IP daily) or vehicle control (DMSO 1:1000). X-rays were obtained twice a week to detect pathologic fractures. Serum OPG levels were measured by ELISA after two weeks of treatment. RESULTS: Mice with bone disease receiving rapamycin had increased serum levels of OPG in the CHLA-20 mice compared to controls (36.89 pg/mL ± 3.90 vs 18.4 pg/mL ± 1.67, p=0.004) and NB1691 tumor-bearing groups (46.03 ± 2.67 pg/mL vs 17.96 ± 1.84pg/mL, p=0.001), and a significantly longer median time to pathologic fractures with CHLA-20 (103 days vs 74.5 days, p=0.014) and NB1691 xenografts. CONCLUSION: In a xenograft model, increased OPG expression correlated with a delay to pathologic fracture suggesting a potential role for mTOR inhibitors in the treatment of neuroblastoma bone metastases.

The effects of irrigation on outcomes in cases of perforated appendicitis in children.

INTRODUCTION: Appendicitis is the most common indication for urgent abdominal operation in children. Approximately 20%-30% of patients will have a perforation at operation. Intra-abdominal abscess after appendectomy is reported in 3%-20% of patients and adds significantly to hospital stay with increased morbidity and overall cost. Surgical dogma has long advocated for irrigation in the setting of gross pus to prevent abscess formation. METHODS: Following IRB approval, data were retrospectively collected for children who had undergone appendectomy for perforated appendicitis at one of two children's hospitals over the course of 5 y. Perforation was determined by review of operative notes. All patients had free fluid in their peritoneal cavity evacuated by suction, whereas some of the patients also had their peritoneal cavity irrigated with normal saline. Postoperative intra-abdominal abscess rates were determined based on clinical symptoms and confirmatory radiologic studies. RESULTS: There were 99 patients in the suction-only group and 139 in the irrigation group. Standard demographics were relatively similar between the two groups. There were significantly lower rates of intra-abdominal abscess formation (4.0% versus 17.2%, P = 0.002) and wound infection (1.0% versus 8.6%, P = 0.003) in the suction-only group compared with the irrigation group. We further analyzed abscess rates by surgical treatment, either laparoscopic or open appendectomy. There were 85 patients in the laparoscopic group and 152 patients in the open appendectomy group. In this subgroup analysis, there were also significantly lower rates of abscess formation in patients treated with suction only compared with irrigation in the laparoscopic (3.5% versus 18.8%, P = 0.012) and open appendectomy groups (4.2% versus 16.3%, P = 0.036). CONCLUSIONS: Results of this retrospective review indicate that a suction-only approach significantly decreased rates of abscess formation and wound infections compared to irrigation in cases of perforated appendicitis in children.

Robot-assisted thoracoscopic thymectomy for treating myasthenia gravis in children.

INTRODUCTION: In the United States, the prevalence of myasthenia gravis (MG) is approximately 14-20 per 100,000. One treatment option involves a thymectomy, which can lead to remission of symptoms. The amount of thymic tissue removed is correlated with a better outcome for patients. Thus, it is critical that the procedure used when performing a thymectomy maximize the resection of thymic tissue. Robotic-assisted thoracoscopic thymectomy provides a minimally invasive platform that avoids the mortality and morbidity of a median sternotomy while providing better visualization and a more delicate dissection than is available in a standard thoracoscopic procedure. PATIENTS AND METHODS: Following Institutional Review Board approval, in total, 9 patients who underwent robotic thymectomy were reviewed. Intraoperative statistics such as operative time and blood loss were reviewed from operative records. Postoperative outcomes such as hospital stay, discharge medications, and complications were reviewed from hospital charts. Lastly, disease response was evaluated in consultation with a pediatric neurologist who specializes in MG. RESULTS: Age at operation ranged from 2 to 15 years of age (average, 9.4 years). A majority of patients had an MGFA classification of II or greater (n=5). All patients were on pyridostigmine preoperatively, and 7 of 9 (77%) were taking prednisone. Mean operative time was 160.1±6.1 minutes. Average postoperative hospital stay was 1.1±0.3 days. One patient had a documented persistent pneumothorax on postoperative Day 1, which was treated with nasal cannula oxygen for an additional day. There were no additional operative complications, and all patients were discharged home on acetaminophen with codeine for pain control. Eight of 9 patients had improvement in MG symptoms after the procedure. CONCLUSIONS: Robotic-assisted thoracoscopic thymectomy is a safe and effective operation for children with MG. Robotic assistance allows for articulating instruments, three-dimensional visualization, and minimal blood loss. These factors may allow for a more complete resection compared with a standard thoracoscopic thymectomy.

Bevacizumab-induced tumor vessel remodeling in rhabdomyosarcoma xenografts increases the effectiveness of adjuvant ionizing radiation.

PURPOSE: Inhibition of vascular endothelial growth factor (VEGF) may effect transient "normalization" of tumor vasculature by pruning immature vessels, resulting in improved tumor perfusion and oxygenation. This may improve the efficacy of adjuvant ionizing radiation (IR). We tested this hypothesis using bevacizumab, an anti-VEGF antibody, in rhabdomyosarcoma (RMS) xenografts. METHODS: Mice bearing orthotopic alveolar RMS xenografts were treated with a single dose of bevacizumab, IR, or a combination of the two on different schedules. Tumors were then evaluated for changes in microvessel density, vessel maturity, vessel permeability, intratumoral oxygenation, as well as altered growth. RESULTS: After bevacizumab treatment, a significant decrease in tumor microvessel density and a significant increase in tumor vessel maturity, defined as the ratio of pericytes to endothelial cells, were observed, suggesting pruning of immature vessels lacking pericytes. Tumor vessel permeability was also significantly decreased and intratumoral oxygen tension increased 2 and 5 days after bevacizumab owing to a transient improvement in tumor perfusion. Treatment with IR 2 or 5 days after bevacizumab resulted in the greatest antitumor activity. CONCLUSION: Our findings support the hypothesis that VEGF inhibition with bevacizumab transiently normalizes the dysfunctional vasculature of RMS xenografts, improving tumor oxygenation and increasing tumor sensitivity to adjuvant IR.

Focal adhesion kinase expression in human neuroblastoma: immunohistochemical and real-time PCR analyses.

PURPOSE: The focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase important in signaling between cells and their extracellular matrix. Studies have shown that FAK expression is up-regulated in several human tumors and is related to tumor progression. We recently found an increase in p125(FAK) expression in human neuroblastoma cells lines and wished to determine its expression in human neuroblastoma specimens and evaluate for a possible correlation between p125(FAK) expression and known prognostic factors for neuroblastoma. We hypothesized that p125(FAK) expression would be up-regulated in advanced human neuroblastomas. EXPERIMENTAL DESIGN: Using immunohistochemical techniques with monoclonal antibody 4.47 specific for p125(FAK) expression, we analyzed 70 formalin-fixed, paraffin-embedded human neuroblastoma specimens for p125(FAK) staining. In addition, real-time PCR was used to determine the abundance of FAK mRNA in 17 matched human neuroblastoma mRNA specimens. RESULTS: FAK staining was present in 51 of the 70 tumor specimens (73%). Immunohistochemical staining of p125(FAK) in the ganglion-type tumor cells correlated with advanced International Neuroblastoma Staging System tumor stages and FAK mRNA abundance. In addition, p125(FAK) staining was significantly increased in stage IV tumors with amplification of the N-MYC oncogene. CONCLUSIONS: These novel findings provide evidence that FAK is expressed by advanced-stage neuroblastoma and provide a rationale for targeting FAK in the treatment of this tumor.

Artificial rearing of mouse pups: development of a mouse pup in a cup model.

Artificial rearing of rat pups has been used in the investigation of the neonatal gut. We propose to adapt the model of artificially rearing rat pups for use in mouse pups, thereby allowing the use of transgenic animals for our research. We hypothesized that gastrostomy catheters may be placed successfully into neonatal mouse pups and that the pups may be artificially reared without significant alterations in their growth or intestinal development. Gastrostomy tubes are placed into 5-d-old mouse pups [artificially reared (AR); n = 32], and the mice are fed rodent milk substitute. Littermate pups [maternally reared (MR); n = 22] are used as controls. After 5 d, pups are killed and their organs are harvested. Intestinal villus measurements, protein content, and DNA content are determined. Data are reported as mean +/- SEM, compared with appropriate statistical methods, and significance is determined at P < 0.05. Initial weights and lengths are not different between the two groups, but after 5 d, MR pups weigh more than their AR counterparts (5.0 +/- 0.13 versus 4.1 +/- 0.14 g, MR versus AR; P < 0.01). However, the pups' length and the intestinal villus height-to-width ratios, protein, and DNA content are not different between the MR and AR pups. To our knowledge, this is the first report of artificially rearing mouse pups. Development of this technique will permit nutritional manipulation in neonatal mice, a mammalian model wherein the genome is sequenced and transgenic mutants are available.