Marcus M. Malek

Embryonic mouse blood flow and oxygen correlate with early pancreatic differentiation

The mammalian embryo represents a fundamental paradox in biology. Its location within the uterus, especially early during development when embryonic cardiovascular development and placental blood flow are not well-established, leads to an obligate hypoxic environment. Despite this hypoxia, the embryonic cells are able to undergo remarkable growth, morphogenesis, and differentiation. Recent evidence suggests that embryonic organ differentiation, including pancreatic β-cells, is tightly regulated by oxygen levels. Since a major determinant of oxygen tension in mammalian embryos after implantation is embryonic blood flow, here we used a novel survivable in utero intracardiac injection technique to deliver a vascular tracer to living mouse embryos. Once injected, the embryonic heart could be visualized to continue contracting normally, thereby distributing the tracer specifically only to those regions where embryonic blood was flowing. We found that the embryonic pancreas early in development shows a remarkable paucity of blood flow and that the presence of blood flow correlates with the differentiation state of the developing pancreatic epithelial cells in the region of the blood flow.

Review of outcomes of primary liver cancers in children: our institutional experience with resection and transplantation.

BACKGROUND Operative intervention plays an important role in the management of primary liver cancers in children. Recent improvements in diagnostic modalities, pre- and postoperative chemotherapy, and operative technique have all led to improved survival in these patients. Both hepatic resection and orthotopic liver transplantation are effective operations for pediatric liver tumors; which intervention is pursued is based on preoperative extent of disease. This is a review of our institutions experience with operative management of pediatric liver cancer over an 18-year period. METHODS A retrospective chart review from 1990 to 2007 identified patients who were ≤18 years old who underwent operative intervention for primary liver cancer. Demographics, type of operation, intraoperative details, pre- and postoperative management, as well as outcomes were recorded for all patients. RESULTS Fifty-four patients underwent 57 operations for primary liver cancer, 30 of whom underwent resection; the remaining 27 underwent orthotopic liver transplantation. The mean age at diagnosis was 41 months. Twenty patients had stage 1 or 2 disease and 34 patients had stage 3 or 4 disease. Forty-eight (89%) patients received preoperative chemotherapy. Postoperative chemotherapy was given to 92% of patients. Mean overall and intensive care unit duration of stay were 18 and 6 days, respectively. About 45% of patients had a postoperative complication, including hepatic artery thrombosis (n = 8), line sepsis (n = 6), mild acute rejection (n = 3), biliary stricture (n = 2), pneumothorax (n = 2), incarcerated omentum (n = 1), Horners syndrome (n = 1), and urosepsis (n = 1). Only 6 patients had a recurrence of their cancer, 5 after liver resection, 3 of whom later received a transplant. There was only 1 recurrence after liver transplantation. There was 1 perioperative mortality from cardiac arrest. Overall survival was 93%. CONCLUSION Operative intervention plays a critical role in the management of primary liver cancer in the pediatric population. Neoadjuvant chemotherapy can be given if the tumor seems unresectable at diagnosis. If chemotherapy is unable to sufficiently downstage the tumor, orthotopic liver transplantation becomes the patients best option. Our institution has had considerable experience with both resection and liver transplantation in the treatment of pediatric primary liver cancer, with good long-term outcomes.

Thoracic neuroblastoma: a retrospective review of our institutional experience with comparison of the thoracoscopic and open approaches to resection

PURPOSE Neuroblastoma is the most common extracranial solid tumor in children. Twenty percent of all neuroblastomas arise in the thorax. This study evaluates the open vs thoracoscopic resection of thoracic neuroblastoma. METHODS A retrospective chart review was conducted from the medical records of all children undergoing resection of a thoracic neuroblastoma from 1990 to 2007 at our institution. We evaluated patients who underwent open vs thoracoscopic resection and compared demographics, pathologic condition, stage, operative details, complications, and outcomes between the 2 groups. RESULTS A total of 149 cases of neuroblastoma were identified during the study period, 36 (24%) of which had tumor located in the thorax. Thirty-six of these patients underwent 37 operations for primary thoracic neuroblastoma. Open thoracotomy was used in 26 cases with the thoracoscopic approach to resection used in the remaining 11. We observed no differences in patient demographics including mean age, sex, or ethnicity. Tumors in both groups were of similar histologic condition, location, surgical margin, lymph node status, and stage. The length of operation was similar between the 2 groups, but length of stay was shorter in the thoracoscopic group (2.0 days; range, 1-7 days vs 3.5 days; range, 2-8 for the open group; P = .01). Estimated blood loss was also less in the minimally invasive group (median, 10 mL; range, 0-75 mL vs 25 mL; 5-650 mL in the open group; P = .02). Review of outcomes showed no significant difference in complications, recurrence, survival, or disease-free survival between these 2 groups. CONCLUSIONS This retrospective review of thoracic neuroblastoma for an 18-year period shows that thoracoscopic resection is an effective approach to this tumor and offers shorter length of stay and decreased blood loss when compared to open thoracotomy.

Laparoscopic Versus Open Distal Pancreatectomy in the Management of Traumatic Pancreatic Disruption

PURPOSE Traumatic pancreatic transection is uncommon. The role of laparoscopy in the setting of this injury has not been well described. PATIENTS AND METHODS Six large-volume pediatric trauma centers contributed patients <18 years of age who underwent a distal pancreatectomy for traumatic pancreatic transection from 2000 to 2010. RESULTS Twenty-one patients without another indication for emergency laparotomy underwent a distal pancreatectomy for Grade III pancreatic injuries, of which 7 underwent laparoscopic distal pancreatectomy. Mean (±SD) age was 8.6±4.7 years, and 67% were male. There was no difference in the presence of other injuries between the two groups (43% in each group). Computed tomography revealed a transected pancreas in 85% of the laparoscopic patients and 75% of the open group (P=1.0). Mean operative time was 218±101 minutes with laparoscopy compared with 195±111 minutes with the open procedure (P=.7). Median duration of hospitalization was 6 days (range, 6-18 days) in the laparoscopic group compared with 11 days (range, 5-26 days) in the open group (P=0.3). Postoperative morbidity was not different between the two groups (57% versus 21% for laparoscopic versus open, P=.2). CONCLUSIONS Laparoscopy is equivalent to open distal pancreatectomy in children with select traumatic pancreatic injuries.

Defective pulmonary innervation and autonomic imbalance in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is associated with significant mortality due to lung hypoplasia and pulmonary hypertension. The role of embryonic pulmonary innervation in normal lung development and lung maldevelopment in CDH has not been defined. We hypothesize that developmental defects of intrapulmonary innervation, in particular autonomic innervation, occur in CDH. This abnormal embryonic pulmonary innervation may contribute to lung developmental defects and postnatal physiological derangement in CDH. To define patterns of pulmonary innervation in CDH, human CDH and control lung autopsy specimens were stained with the pan-neural marker S-100. To further characterize patterns of overall and autonomic pulmonary innervation during lung development in CDH, the murine nitrofen model of CDH was utilized. Immunostaining for protein gene product 9.5 (a pan-neuronal marker), tyrosine hydroxylase (a sympathetic marker), vesicular acetylcholine transporter (a parasympathetic marker), or VIP (a parasympathetic marker) was performed on lung whole mounts and analyzed via confocal microscopy and three-dimensional reconstruction. Peribronchial and perivascular neuronal staining pattern is less complex in human CDH than control lung. In mice, protein gene product 9.5 staining reveals less complex neuronal branching and decreased neural tissue in nitrofen-treated lungs from embryonic day 12.5 to 16.5 compared with controls. Furthermore, nitrofen-treated embryonic lungs exhibited altered autonomic innervation, with a relative increase in sympathetic nerve staining and a decrease in parasympathetic nerve staining compared with controls. These results suggest a primary defect in pulmonary neural developmental in CDH, resulting in less complex neural innervation and autonomic imbalance. Defective embryonic pulmonary innervation may contribute to lung developmental defects and postnatal physiological derangement in CDH.

The Expression and Function of Glucose-Dependent Insulinotropic Polypeptide in the Embryonic Mouse Pancreas

OBJECTIVE Glucose-dependent insulinotropic polypeptide (GIP) is a member of a structurally related group of hormones that also includes glucagon, glucagon-like peptides, and secretin. GIP is an incretin, known to modulate glucose-induced insulin secretion. Recent studies have shown that glucagon is necessary for early insulin-positive differentiation, and a similar role for incretins in regulating embryonic insulin-positive differentiation seems probable. Here we studied the role of GIP signaling in insulin-positive differentiation in the embryonic mouse pancreas. RESEARCH DESIGN AND METHODS The ontogeny of the GIP ligand and GIP receptor in the embryonic pancreas was investigated by immunohistochemistry and RT-PCR. GIP signaling was inhibited in cultured embryonic pancreata using morpholine-ring antisense against GIP ligand and receptor, or small interfering RNA (siRNA) for GIP ligand and receptor. Markers of endocrine cells and their progenitors were studied by immunohistochemistry and RT-PCR. RESULTS GIP and GIP receptor mRNA were both detected in the embryonic pancreas by embryonic day 9.5 and then persisted throughout gestation. GIP was generally coexpressed with glucagon by immunostaining. The GIP receptor was typically coexpressed with insulin. Morpholine-ring antisense or siRNA against either GIP ligand or GIP receptor both inhibited the differentiation of insulin-positive cells. Inhibition of GIP or its receptor also led to a decrease in the number of Pdx-1–positive and sox9-positive cells in the cultured embryonic pancreas. The number of Pax6- and Nkx2.2-positive cells, representative of developing pancreatic endocrine cells and β-cells, respectively, was also decreased. CONCLUSIONS GIP signaling may play a role in early embryonic pancreas differentiation to form insulin-positive cells or β-cells.

Congenital H-type tracheoesophageal fistula: A multicenter review of outcomes in a rare disease

OBJECTIVE To perform a multicenter review of outcomes in patients with H-type tracheoesophageal fistula (TEF) in order to better understand the incidence and causes of post-operative complications. BACKGROUND H-type TEF without esophageal atresia (EA) is a rare anomaly with a fundamentally different management algorithm than the more common types of EA/TEF. Outcomes after surgical treatment of H-type TEF are largely unknown, but many authoritative textbooks describe a high incidence of respiratory complications. METHODS A multicenter retrospective review of all H-type TEF patients treated at 14 tertiary childrens hospital from 2002-2012 was performed. Data were systematically collected concerning associated anomalies, operative techniques, hospital course, and short and long-term outcomes. Descriptive analyses were performed. RESULTS We identified 102 patients (median 9.5 per center, range 1-16) with H-type TEF. The overall survival was 97%. Most patients were repaired via the cervical approach (96%). The in-hospital complication rate, excluding vocal cord issues, was 16%; this included an 8% post-operative leak rate. Twenty-two percent failed initial extubation after repair. A total of 22% of the entire group had vocal cord abnormalities (paralysis or paresis) on laryngoscopy that were likely because of recurrent laryngeal nerve injury. Nine percent required a tracheostomy. Only 3% had a recurrent fistula, all of which were treated with reoperation. CONCLUSIONS There is a high rate of recurrent laryngeal nerve injury after H-type TEF repair. This underscores the need for meticulous surgical technique at the initial repair and suggests that early vocal cord evaluation should be performed for any post-operative respiratory difficulty. Routine evaluation of vocal cord function after H-type TEF repair should be considered. THE LEVEL OF EVIDENCE RATING Level IV.

Laparoscopic splenic-preserving distal pancreatectomy for trauma in a child

PurposeTo reduce the risks associated with splenectomy, there has been a trend toward splenic preservation when performing distal pancreatectomy. Although laparoscopy has gained almost universal acceptance, it is still not utilized often for pancreatic surgery in children. In fact, review of the literature shows only a few case series of splenic-preserving laparoscopic distal pancreatectomy, and even less reported experience in the pediatric population [1–3]. To our knowledge, there has been only one other report of laparoscopic spleen-preserving distal pancreatectomy in the setting of trauma in a child [4].MethodsA 13-year-old boy suffered a handlebar injury to the abdomen secondary to a dirt bike accident. He did not report loss of consciousness but complained of abdominal pain. CT scan revealed a grade II splenic laceration with a transected distal pancreas. He was hemodynamically stable with a large contusion in the left upper quadrant. Laboratory evaluation showed that his hematocrit was stable but was significant for elevated amylase and lipase. During his hospitalization, he developed significant abdominal distension and his amylase and lipase continued to rise. He was taken to the operating room for definitive management of his pancreatic injury 72 hours after his initial injury.ResultsIn the operating room, a central line was placed so that he could receive total parenteral nutrition postoperatively. The video demonstrates the performance of a laparoscopic spleen-preserving distal pancreatectomy. There was a fair amount of old blood seen in the left upper quadrant and behind the pancreas. There was no evidence of active bleeding. The operation was performed without complication and with preservation of the splenic vessels.ConclusionsThe postoperative course was very smooth with the child resuming diet by postoperative day (POD) 4. He was sent home on POD 7. This video demonstrates that in the proper trauma patient, a minimally invasive approach to a spleen-preserving distal pancreatectomy can still be performed.

Use of intraoperative nuclear imaging leads to decreased anesthesia time and real-time confirmation of lesion removal

BACKGROUND Lymphatic mapping to guide sentinel lymph node biopsy (SLNB) typically requires lymphoscintigraphy prior to surgery. In young pediatric patients, this process often requires intubation in the nuclear medicine suite followed by transport to the operating room (OR). METHODS We reviewed 14 pediatric cases in which a portable nuclear imaging camera was utilized to perform the entirety of the SLNB in the OR. RESULTS AND CONCLUSION This method, utilizing intraoperative nuclear imaging, helped to confirm removal of the sentinel lymph node in real time, decreased anesthesia time, and avoided transport of a sedated or intubated child. LEVEL OF EVIDENCE III.

Development of a novel technique for bilateral rectus sheath nerve blocks under laparoscopic-guidance ☆

BACKGROUND Bilateral rectus sheath blocks have proven to be superior to local anesthetic infiltration for umbilical incisions and have been gaining popularity for the treatment of perioperative pain in children. We aim to develop a technique of surgeon performed rectus sheath blocks under laparoscopic-guidance alone. METHODS In phase I, we observed the laparoscopic appearance of a rectus sheath block. The pain management team performed an ultrasound-guided rectus sheath nerve block as we visualized the posterior rectus sheath with the laparoscope. In phase II, after completion of the laparoscopic procedure, we performed a rectus sheath nerve block. Ultrasound was used to identify where the local anesthetic had been injected. RESULTS Nineteen patients were included in this study, accounting for 38 rectus sheath blocks. In phase I, we observed with the laparoscope the delivery of ten ultrasound-guided rectus sheath blocks. In phase II, 28 laparoscopic-guided rectus sheath blocks were completed with immediate ultrasound confirmation of correct placement. CONCLUSIONS We have demonstrated that the rectus sheath nerve block can be performed reliably under laparoscopic-guidance alone. The efficacy of the laparoscopic-guided nerve block compared to the ultrasound-guided approach will need further study in a prospective, randomized trial. TYPE OF STUDY Retrospective review. LEVEL OF EVIDENCE 3.