Early chimerism threshold predicts sustained engraftment and NK-cell tolerance in prenatal allogeneic chimeras.

The failure of engraftment in human cases of in utero hematopoietic cell transplantation (IUHCT) in which no immunodeficiency exists suggests the presence of an unrecognized fetal immune barrier. A similar barrier in murine IUHCT appears to be dependent on the chimerism level and is poorly explained by a lack of T-cell tolerance induction. Therefore, we studied the effect of the chimerism level on engraftment and host natural killer (NK)-cell education in a murine model of IUHCT. The dose of transplanted cells was found to exhibit a strong correlation with both the engraftment rate and chimerism level. More specifically, a threshold level of initial chimerism (> 1.8%) was identified that predicted durable engraftment for allogeneic IUHCT, whereas low initial chimerism (< 1.8%) predicted a loss of engraftment. NK cells taken from chimeras above the "chimerism threshold" displayed durable calibration of alloresponsive Ly49A receptors and tolerance to donor antigens. Depletion of recipient NK cells stabilized engraftment in low-level chimeras (< 1.8%). These studies illustrate the importance of the early chimerism threshold in predicting long-term engraftment and host NK-cell tolerance after in utero transplantation.

KIR receptor-ligand incompatibility predicts killing of osteosarcoma cell lines by allogeneic NK cells.

BACKGROUND: The effectiveness of killer immunoglobulin-like receptor (KIR) incompatible, alloreactive natural killer (NK) cells has been primarily documented in hematological malignancies following stem-cell transplant. This effect has not been thoroughly evaluated for pediatric solid tumors. In this study, we evaluated KIR receptor-ligand incompatibility of NK cells against osteosarcoma cell lines. PROCEDURE: Following the KIR receptor-ligand mismatch model, MHC I cell surface expression and KIR ligand mRNA content of 3 osteosarcoma cell lines was determined by flow cytometry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. NK cells were isolated from healthy volunteer donor peripheral blood mononuclear cells (PBMCs) and KIR surface expression determined by flow cytometry. An Annexin-V based flow cytometric killing assay was used to determine % of dying osteosarcoma target cells by donor NK effector cells. RESULTS: One of seven healthy volunteer donors tested lacked phenotypic expression of one KIR. However, variable expression of KIR ligands was observed in 3 osteosarcoma cell lines. The highest rates of dying cells were seen in osteosarcoma cells with the lowest KIR ligand expression. Following down-regulation of KIR ligand expression, an increased susceptibility to NK cell-mediated killing was observed in a previously NK-resistant osteosarcoma cell line. CONCLUSIONS: Variable MHC I and KIR ligand expression was observed in osteosarcoma cell lines and this resulted in variable susceptibility to NK cell-mediated killing predicted by the degree of KIR receptor-ligand incompatibility. Collectively, these data provide rationale for the study of KIR incompatible stem-cell transplant for osteosarcoma, although further studies with fresh osteosarcoma samples are necessary.

Surgical resident's training in colonoscopy: numbers, competency, and perceptions.

BACKGROUND: There is currently great discrepancy in the training requirements between medical societies regarding the recommended threshold number of colonoscopies needed to assess for technical competence. Our goal was to determine the number of colonoscopies performed by surgical residents, rate of cecal intubation, as well as trainee perceptions of colonoscopy training after completion of their training period. METHODS: This study consisted of a 12-item electronic survey completed by 21 surgical residents after their 2-month endoscopy rotation at a tertiary care, urban referral center. This survey assessed numbers of colonoscopies performed, number successful to the cecum, and perceptions of training in colonoscopy. The cecal intubation rate was used as a surrogate marker of technical competence. RESULTS: Twenty-one surgical residents performed a mean of 80 ± 35 total colonoscopies during the 2-month rotation. The average cecal intubation rate was 47% (range 9-78%). Resident comfort level for independently performing a total colonoscopy was scored a mean 3.6 on scale of 1-5 (5 = most comfortable), and 43% of the surgical residents planned on performing colonoscopy after residency training. CONCLUSIONS: Surgical residents can obtain the recommended threshold for colonoscopy (N = 50) during a standard 2-month rotation. However, no resident was able to achieve technical competence in colonoscopy as defined by a 90% cecal intubation rate. These data suggest that the method of training of general surgery residents in colonoscopy may need reappraisal.

Recent advances and controversies in pediatric laparoscopic surgery.

Children represent a unique group of patients who are likely to greatly benefit from minimally invasive surgery (MIS). The promise of less postoperative pain, smaller scars, shorter hospital stays, and a faster return to school continues to drive growth in this area. The development of pediatric-specific techniques and documentation of improved outcomes form a critical gateway to widespread application of pediatric MIS. A brief perspective on current approaches to MIS for pediatric congenital and acquired disease is provided in this report. Technical departures from standardized adult MIS and the rationale for their modification are highlighted.

Passing the baton: The pediatric surgical perspective on transition.

BACKGROUND/PURPOSE: Transition of care from pediatric to adult providers is garnering intense national interest in pediatrics but is largely driven by nonsurgeons. We sought to describe the preferences of pediatric surgeons and their current transition practice patterns for various populations and wondered whether gender, experience, or practice setting affected surgeons' perspectives. METHODS: All American Pediatric Surgical Association (APSA) members were surveyed electronically. Responses were voluntary and confidential. RESULTS: Survey response rate was 22%. Most surgeons (95%) treated patients up to 22 years of age, and many cared for older patients (23-26 years, 49%; 27-30 years, 25%; 31-40 years, 18%; >40 years, 13%). Developmentally delayed adults comprised a significant portion of this population (54%). Congenital conditions such as Hirschsprung disease (25%), anorectal malformations (22%) and cystic fibrosis (22%) were most commonly reported. About half (52%) of respondents reported institutional limits for age. Lack of qualified adult surgeons was felt to be the greatest barrier to transition (p<0.001). Experience, gender and practice type did not significantly affect opinions of transition. CONCLUSIONS: Pediatric surgeons care for adult patients with a variety of surgical conditions, particularly those with developmental delay and congenital anomalies. The perception of a deficit of qualified adult providers warrants further exploration. Understanding the barriers to surgical transition represents a critical step in improving the quality and appropriateness of care transitions.

Operative indications in recurrent ileocolic intussusception.

BACKGROUND: Air-contrast enema (ACE) is standard treatment for primary ileocolic intussusception. Management of recurrences is less clear. This study aimed to delineate appropriate therapy by quantifying the relationship between recurrence and need for bowel resection, pathologic lead points (PLP), and complication rates. METHODS: After IRB approval, a single institution review of patients with ileocolic intussusception from 1997 to 2013 was performed, noting recurrences, outcomes, and complications. Fisher's exact and t-tests were used. RESULTS: Of 716 intussusceptions, 666 were ileocecal. Forty-four underwent bowel resection, with 29 PLPs and 9 ischemia/perforation. Recurrence after ACE occurred in 96 (14%). Recurrence did not predict PLP (P=0.25). Recurrence (≥3) was associated with higher resection rate (P=0.03), but not ischemia/perforation (P=0.75). ACE-related complications occurred in 4 (0.5%) patients. Successful initial ACE had 98% negative predictive value for resection and PLP (e.g., after successful ACE, 2% had resections, 2% PLP). After failed initial ACE, 36% received resection, and 23% had PLP (P<0.001). CONCLUSIONS: Recurrence is associated with a greater risk of resection but not PLP or ACE-complication. Failed ACE is associated with increased risk for harboring PLP and receiving resection. ACE should be the standard treatment in recurrent intussusception, regardless of number of recurrences.

Trogocytosis as a mechanistic link between chimerism and prenatal tolerance.

In utero hematopoietic cellular transplantation (IUHCT) holds great promise for the treatment of congenital diseases of cellular dysfunction such as sickle cell disease, immunodeficiency disorders and inherited metabolic disorders. However, repeated failures in clinical cases of IUHCT that do not involve an immunodeficiency disease force a closer examination of the fetal immune system. While the mechanisms regulating T cell tolerance have been previously studied, the educational mechanisms leading to NK cell tolerance in prenatal chimeras remain unknown. As a low level of donor cells (1.8%) is required to induce and maintain this tolerance, it is likely that these mechanisms employ indirect host-donor interaction. This report examines donor-to-host MHC transfer (trogocytosis) as an intrinsic mechanism regulating the development and maintenance of NK cell tolerance in prenatal chimeras. The findings demonstrate that phenotypically tolerant host NK cells express low levels of transferred donor MHC antigens during development and later as mature cytotoxic lymphocytes. Further study is needed to understand how the cis-recognition of transferred donor MHC ligand influences the selection and maintenance of tolerant NK cells in prenatal chimeras.

Enlarging unilateral breast mass in an adolescent male: an unusual presentation of intraductal papilloma.

Breast masses presenting in adolescent boys are rare and are almost uniformly owing to gynecomastia. Although surgical referral for breast masses in adolescent boys is common, intervention is typically for cosmesis. We report the case of a 14-year-old boy who presented with an enlarging unilateral breast mass, which was found to be owing to an intraductal papilloma at the time of surgical excision.

Regulation of the earliest immune response to in utero hematopoietic cellular transplantation.

In Utero Hematopoietic Cellular Transplantation (IUHCT) is a promising intervention to treat a wide range of congenital disease. Through the presentation of donor cells to the immature immune system, mixed hematopoietic chimerism and donor-specific tolerance can be achieved. However, the failure of engraftment in prenatal recipients in which no immunodeficiency exists suggests the existence of a fetal immune barrier to transplantation. Although the possible barriers include effectors of the adaptive and innate immune system, our recent findings and ongoing investigations indicate that the barrier most likely resides in the developing NK cells. A chimerism level above a certain threshold during NK cell development is necessary to overcome rejection. Clinically, this transplantation barrier might also exist in early human fetal NK cells. Understanding the fetal immune barrier to allotransplantation is essential in advancing clinical application of IUHCT. Herein, we provide a short summary and new evidence for the earliest immune response to prenatal transplantation.

What is the optimal treatment for children with primary hyperparathyroidism?

PURPOSE: Little information exists regarding the optimal surgical treatment of pediatric primary hyperparathyroidism. We hypothesized that primary hyperparathyroidism in children, in the absence of a family history, is caused by single-gland disease and is amenable to minimally invasive parathyroidectomy (MIP). METHODS: We reviewed the records of individuals younger than 25 years who underwent parathyroidectomy in a prospectively collected database at a single tertiary hospital from 2003 to 2009. RESULTS: Twenty-five patients were identified, with a mean (SD) age of 19 (3.7) years. Sixty percent had single-gland disease (n = 15). Familial disease was present in 6 patients. All of the children younger than 18 years without a family history of disease (9/9) were found to have a single-gland disease (P < .001). Seventy-eight percent of patients without a family history were successfully treated without a bilateral exploration. Average length of stay was less than 1 day with no complications or recurrences. CONCLUSIONS: Primary hyperparathyroidism in patients younger than 18 years without a family history was uniformly caused by single-gland disease. Minimally invasive parathyroidectomy was successful in these patients and avoided the morbidity of bilateral exploration. We recommend MIP be used in pediatric patients at large referral centers with prior successful institutional experience with the technique.

Donor major histocompatibility complex class I expression determines the outcome of prenatal transplantation.

PURPOSE: The failure of in utero transplantation in immune-competent recipients suggests the existence of a fetal immune barrier. The importance of donor major histocompatibility complex (MHC) class I expression in the induction of prenatal tolerance remains undefined. We hypothesized that donor cell MHC class I expression facilitates engraftment in prenatal allogeneic recipients rather than promoting immune rejection. METHODS: B6.Ly5.2 (class I(+)) or B6.TAP(-/-) (class I(-)) murine fetal liver cells were transplanted into age-matched allogeneic fetal recipients. Survival to weaning and subsequent growth was assessed. Engraftment rates and peripheral blood chimerism levels were measured serially. RESULTS: The presence or absence of class I expression did not affect survival or growth of recipients and no graft-vs-host disease developed. Allogeneic recipients of B6.Ly5.2 cells exhibited significantly higher levels of donor hematopoietic chimerism when compared to recipients of B6.TAP(-/-) cells (27% + 10% vs 11% + 8%; P = .004) that deteriorated further over time. CONCLUSIONS: Donor class I MHC antigen expression is essential for stable long-term engraftment and maintenance of donor-specific tolerance. Further studies are needed to better characterize the role of the fetal innate immune system in prenatal allotransplantation.

Early laparoscopic fundoplication and gastrostomy in infants with spinal muscular atrophy type I.

BACKGROUND/PURPOSE: Spinal muscular atrophy (SMA) in children leads to progressive muscle weakness, dysphagia, aspiration, and death. We hypothesized that early laparoscopic fundoplication and gastrostomy in infants with SMA type I could be performed safely perhaps leading to fewer aspiration events and improved nutritional status. METHODS: Children diagnosed with SMA type I from 2002 through 2005 were included (n = 12). All children underwent laparoscopic Nissen fundoplication with gastrostomy shortly after diagnosis. Postoperative respiratory management and discharge criteria were standardized. RESULTS: All patients were extubated immediately postoperatively. There were no significant complications. Average time to full feeding and inpatient length of stay were 42 +/- 4.9 hours (range, 30-48 hours) and 78 +/- 22.5 hours (range, 44-120 hours), respectively. Mean weight-for-length percentile was doubled at 1 year postoperatively (P = .03). The number of respiratory-related hospitalizations in the cohort decreased by almost 50% in the ensuing 12 months after surgery, although this did not reach statistical significance in this small cohort (P = .34). CONCLUSIONS: Early laparoscopic fundoplication and gastrostomy is safe and is associated with improved nutritional status. A trend toward fewer significant long-term aspiration-related events was seen after fundoplication. To better assess the long-term benefits of performing an antireflux procedure in these high-risk patients, a larger prospective trial comparing current nutritional support practices is needed.

Age-related differences in diagnosis and morbidity of intestinal malrotation.

BACKGROUND: Intestinal malrotation in adulthood may present with a variety of chronic symptoms. Surgical intervention frequently leads to other complications in these patients. We hypothesized that the chronic nature of malrotation in adults could cause a delay in diagnosis and increased perioperative complications. STUDY DESIGN: All patients diagnosed with intestinal malrotation from July 2002 through July 2006 were included. IRB approval was obtained. Outcomes in patients less than 16 years of age were compared with outcomes from those older than 16. Presenting symptoms, initial diagnosis, results of imaging data, and time to diagnosis were evaluated. Surgical management, resulting complications, and rate of reoperation were analyzed. RESULTS: Twenty-four patients with intestinal malrotation were identified (age range, 10 days to 89 years old; 10 adults, 14 children). Seventy percent of adults experienced chronic symptoms for 6 months or more before the diagnosis of malrotation was made (children, 14%, p = 0.017). No patients in the adult group were initially diagnosed with malrotation, although 57% of children were correctly diagnosed at the time of presentation of symptoms (p=0.006). Postoperative complications occurred in 60% of adults, but in only 29% of children, though this did not reach significance (p=0.211). Forty percent of adult patients required reoperation (p=0.020). CONCLUSIONS: Intestinal malrotation in adults is often associated with a delay in diagnosis and increased morbidity. Enhanced awareness of this entity in adults may enhance patient counseling and improve therapeutic outcomes in these patients.

Thoracoscopic aortopexy for primary tracheomalacia in a 12-year-old.

Aortopexy is the therapeutic modality of choice for severe primary tracheomalacia. The thoracoscopic approach has been used with good results in infants and toddlers, but little information exists on the use of aortopexy in older children. We present the case of a boy with a lifelong history of refractory, a steroid-dependent reactive airway disease, and who was found to have severe primary tracheomalacia. He subsequently underwent thoracoscopic aortopexy with immediate resolution of the tracheomalacia as demonstrated by serial bronchoscopy and long-term resolution of his clinical respiratory symptoms at 1 year.

Acute diverticulitis after Duhamel-Martin procedure for total colonic Hirschsprung's disease.

A 28-year-old man with a history of total colonic Hirschsprung's disease treated with a Duhamel-Martin procedure in infancy, presented with signs and symptoms of acute colonic diverticulitis. Flexible sigmoidoscopy demonstrated a 20 cm jejunocolonic anastomosis, consistent with his previous operation in childhood, with a large diverticulum at the proximal end of the anastomosis containing fecal concretions. The patient returned one month later after a course of antibiotics for definitive resection of the diverticulum. Intra-operative colonoscopy localized three large diverticula and resection of the involved segment was performed. The case is presented as an adult complication of total colonic Hirschsprung's disease treated with childhood resection and reconstruction.