Simulations of sea urchin early development delineate the role of oriented cell division in the morula-to-blastula transition.

The sea urchin morula to blastula transition has long been thought to require oriented cell divisions and blastomere adherence to the enveloping hyaline layer. In a computer simulation model, cell divisions constrained by a surface plane division rule are adequate to effect morphological transition. The hyaline membrane acts as an enhancer but is not essential. The model is consistent with the orientation of micromere divisions and the open blastulae of direct developing species. The surface plane division rule precedes overt epithelization of surface cells and acts to organize the developing epithelium. It is a universal feature of early metazoan development and simulations of non-echinoid cleavage patterns support its role throughout Metazoa. The surface plane division rule requires only local cues and cells need not reference global positional information or embryonic axes.

Treatment of Idiopathic Scoliosis With Vertebral Body Stapling.

STUDY DESIGN: Retrospective cohort. OBJECTIVES: Identify the effectiveness of vertebral body stapling (VBS) in children with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: VBS has been proposed as an alternative to bracing moderate curves in patients with adolescent idiopathic scoliosis (AIS) although a clear picture of comparative efficacy and safety remains to be established. METHODS: Ten skeletally immature patients with AIS and curves between 25° and 35° underwent anterior VBS by a single surgeon from 2008 to 2018. Indications included strong family history, high ScoliScore, curve progression despite bracing, or as an alternative for patients/families refusing bracing. Patients with thoracic kyphosis greater than 40°, curvature with a level above T4 or below L4, and double major curves were contraindicated. Patients with hybrid surgical plans or those who failed to reach skeletal maturity were excluded. Age, gender, levels stapled, pre- and postoperative radiographs, and incidence of secondary surgical intervention were evaluated. Outcomes were also compared with untreated and braced subjects from the BrAIST study. RESULTS: Ten patients met the inclusion criteria. Average age at VBS was 11.8 (9.7-13.5) with an average major Cobb angle of 30.9° (26°-35°). Average duration of follow-up was 6.4 years. All patients demonstrated curve correction at their first postoperative visit. At final follow-up, 50% of patients experienced curve progression greater than 5°, whereas the remaining 50% either remained stable or corrected over time. The five patients whose curves progressed underwent VBS at a significantly younger age (10.8 vs. 12.8; p value .003). Four of these patients required additional surgical intervention for worsening scoliosis. CONCLUSIONS: Although early outcomes after VBS appear to parallel the results of bracing, stapling does not affect the percentage of patients ultimately requiring PSIF. Initial curve correction degraded over time in younger patients with significant growth remaining, and high rates of progression in this group, even with bracing, merits investigation into more efficacious treatment strategies. LEVEL OF EVIDENCE: Level III.

Use of a Capture-Guidance Surgical Instrument to Minimize Muscle Stripping During Nuss Repair of Pectus Excavatum.

Background: Pectus excavatum is an anomaly of chest wall development in which anterior ribs curve inward and the sternum is displaced toward the vertebral column. The Nuss procedure is a minimally invasive technique in which one or more metal bars are implanted to brace the sternum in a corrected position. Over time, the chest wall remodels into an anatomically corrected shape and the bar(s) are removed at a later date. During the procedure, passage of an introducer instrument and then the repair bar(s) may shear the intercostal muscles from the adjacent ribs. This creates larger than necessary defects in the chest wall, improper or unstable bar placement, and inadequate repair. Instrument Design: We report a new surgical instrument for guiding the introducer through the contralateral chest wall. This capture-guidance instrument (CGI) redirects and channels forces to keep the introducer true while preventing muscle stripping during passage of the introducer and repair bar(s). Instrument Use: The CGI has been piloted at two pectus centers with a notable decrease in intercostal muscle stripping. Conclusion: The CGI addresses the problem of shear and intercostal muscle stripping during traversal of the chest as part of Nuss repair of pectus excavatum.

An Evidence-Based Approach to Management of Pectus Excavatum and Carinatum.

Pectus excavatum (PE) and pectus carinatum (PC) are the most common congenital chest wall anomalies. Current research suggests that PE and PC may result from overgrowth of the sternocostal cartilages. This can produce a deformation that displaces the sternum inward as in PE or outward as in PC. The etiology, clinical presentation, evaluation, and management of PE and PC are reviewed. Varied clinical presentations, cardiopulmonary effects, and psychosocial aspects are described.

Two decades of experience with thoracoscopic lobectomy in infants and children: standardizing techniques for advanced thoracoscopic surgery.

OBJECTIVES: This study evaluates the safety and efficacy of thoracoscopic lobectomy in infants and children. MATERIALS AND METHODS: From January 1994 to November 2013, 347 patients underwent video-assisted thoracoscopic lobe resection at two institutions. All procedures were performed by or under the direct guidance of a single surgeon. Patients' ages ranged from 1 day to 18 years, and weights ranged from 2.8 to 78 kg. Preoperative diagnosis included sequestration/congenital pulmonary airway malformation (n=306), severe bronchiectasis (n=24), congenital lobar emphysema (n=13), and malignancy (n=4). RESULTS: Of the 347 procedures, 342 were completed thoracoscopically. Operative times ranged from 35 minutes to 240 minutes (average, 115 minutes). Average operative time when a trainee was the primary surgeon was 160 minutes. There were 81 upper, 25 middle, and 241 lower lobe resections. There were four intraoperative complications (1.1%) requiring conversion to an open thoracotomy. The postoperative complication rate was 3.3%, and 3 patients required re-exploration for a prolonged air leak. Hospital length of stay (LOS) ranged from 1 to 16 days (average). In patients <5 kg and <3 months of age, the average operative time was 90 minutes, and the LOS was 2.1 days. CONCLUSIONS: Thoracoscopic lung resection is a safe and efficacious technique. With proper mentoring it is an exportable technique, which can be performed by pediatric surgical trainees. The procedures are safe and effective even when performed in the first 3 months of life. Early resection avoids the risk of later infection and malignancy.

Local cell interactions and self-amplifying individual cell ingression drive amniote gastrulation.

Gastrulation generates three layers of cells (ectoderm, mesoderm, endoderm) from a single sheet, while large scale cell movements occur across the entire embryo. In amniote (reptiles, birds, mammals) embryos, the deep layers arise by epithelial-to-mesenchymal transition (EMT) at a morphologically stable midline structure, the primitive streak (PS). We know very little about how these events are controlled or how the PS is maintained despite its continuously changing cellular composition. Using the chick, we show that isolated EMT events and ingression of individual cells start well before gastrulation. A Nodal-dependent 'community effect' then concentrates and amplifies EMT by positive feedback to form the PS as a zone of massive cell ingression. Computer simulations show that a combination of local cell interactions (EMT and cell intercalation) is sufficient to explain PS formation and the associated complex movements globally across a large epithelial sheet, without the need to invoke long-range signalling.DOI: http://dx.doi.org/10.7554/eLife.01817.001.

Rectal perforation secondary to rape and fisting in a female adolescent.

We present the case of a 16-year-old girl who was sexually assaulted with transanal forearm penetration resulting in rectal perforation. She required a sigmoid colostomy that was later reversed. The patient's history and physical examination was complicated by multiple factors: she was intoxicated at the time of presentation as well as during the assault; her presentation fluctuated over time, she was obese, and she carried a psychiatric diagnosis. This case report documents a rare injury caused by sexual assault in the adolescent population and also serves as a platform to discuss the evaluation and management of pediatric victims of sexual assault. We support a collaborative model of care including qualified sexual assault pediatricians, sexual assault nurse (or forensic) examiners, medical specialists, and the criminal justice system. The importance of developing updated sexual assault protocols, ensuring their implementation, and maintaining continuous quality assurance cannot be overemphasized.

Central pancreatectomy with pancreaticogastrostomy in children.

Children requiring surgical intervention for pancreatic disease may be at risk long term for exocrine insufficiency and glucose intolerance. Pediatric surgeons must balance the need to perform adequate surgical resection while preserving as much normal pancreatic parenchyma as possible. Neoplasms of the middle pancreatic segment with low malignant potential and isolated trauma to the pancreatic body or neck represent 2 conditions where extensive pancreatic resection is unnecessary. Central pancreatectomy for such lesions is well described in adults. Reconstruction of the distal pancreatic remnant is traditionally performed via Roux-en-Y pancreaticojejunostomy. Pancreaticogastrostomy is an alternative approach that has been used to reconstruct the distal pancreas in the adults. Pancreaticogastrostomy offers several technical advantages over pancreaticojejunostomy. Because children may be uniquely susceptible to the long-term consequences of excessive pancreatic resection, 2 cases using this technique of central pancreatectomy with pancreaticogastrostomy are described.

Computer simulation analysis of normal and abnormal development of the mammalian diaphragm.

BACKGROUND: Congenital diaphragmatic hernia (CDH) is a birth defect with significant morbidity and mortality. Knowledge of diaphragm morphogenesis and the aberrations leading to CDH is limited. Although classical embryologists described the diaphragm as arising from the septum transversum, pleuroperitoneal folds (PPF), esophageal mesentery and body wall, animal studies suggest that the PPF is the major, if not sole, contributor to the muscular diaphragm. Recently, a posterior defect in the PPF has been identified when the teratogen nitrofen is used to induce CDH in fetal rodents. We describe use of a cell-based computer modeling system (Nudge++) to study diaphragm morphogenesis. METHODS AND RESULTS: Key diaphragmatic structures were digitized from transverse serial sections of paraffin-embedded mouse embryos at embryonic days 11.5 and 13. Structure boundaries and simulated cells were combined in the Nudge++ software. Model cells were assigned putative behavioral programs, and these programs were progressively modified to produce a diaphragm consistent with the observed anatomy in rodents. Homology between our model and recent anatomical observations occurred under the following simulation conditions: (1) cell mitoses are restricted to the edge of growing tissue; (2) cells near the chest wall remain mitotically active; (3) mitotically active non-edge cells migrate toward the chest wall; and (4) movement direction depends on clonal differentiation between anterior and posterior PPF cells. CONCLUSION: With the PPF as the sole source of mitotic cells, an early defect in the PPF evolves into a posteromedial diaphragm defect, similar to that of the rodent nitrofen CDH model. A posterolateral defect, as occurs in human CDH, would be more readily recreated by invoking other cellular contributions. Our results suggest that recent reports of PPF-dominated diaphragm morphogenesis in the rodent may not be strictly applicable to man. The ability to recreate a CDH defect using a combination of experimental data and testable hypotheses gives impetus to simulation modeling as an adjunct to experimental analysis of diaphragm morphogenesis.

Thymoma in Children: Report of Two Cases and Review of Literature.

Thymoma is an uncommon tumor of childhood. Stage of the tumor is an independent prognostic factor for survival. Surgery is the treatment of choice for stage I and stage II tumors. Chemotherapy is reserved for patients with refractory or metastatic disease. Thymomas are moderately radiosensitive. However, radiation therapy is not an attractive option for children due to its side-effects on developing organs. The authors describe 2 children with completely encapsulated thymoma who were successfully treated with surgery alone. Both patients remain free of disease 3 years after surgery. One of the patients also has nevus sebaceous. The authors also discuss the possible association between the two disease entities.

Thymoma in children: report of two cases and review of literature.

Thymoma is an uncommon tumor of childhood. Stage of the tumor is an independent prognostic factor for survival. Surgery is the treatment of choice for stage I and stage II tumors. Chemotherapy is reserved for patients with refractory or metastatic disease. Thymomas are moderately radiosensitive. However, radiation therapy is not an attractive option for children due to its side-effects on developing organs. The authors describe 2 children with completely encapsulated thymoma who were successfully treated with surgery alone. Both patients remain free of disease 3 years after surgery. One of the patients also has nevus sebaceous. The authors also discuss the possible association between the two disease entities.