Facultatively ectoparasitic mites as vectors for entomopathogenic bacteria in Drosophila.

Opportunistic bacterial infections are common in insect populations but there is little information on how they are acquired or transmitted. We tested the hypothesis that Macrocheles mites can transmit systemic bacterial infections between Drosophila hosts. We found that 24% of mites acquired detectable levels of bacteria after feeding on infected flies and 87% of infected mites passed bacteria to naïve recipient flies. The probability that a mite could pass Serratia from an infected donor fly to a naïve recipient fly was 27.1%. These data demonstrate that Macrocheles mites are capable of serving as vectors of bacterial infection between insects.

Phenotypic plasticity more essential to maintaining variation in host-attachment behaviour than evolutionary trade-offs in a facultatively parasitic mite.

A prevailing hypothesis for the evolution of parasitism posits that the fitness benefits gained from parasitic activity results in selection for and fixation of parasitic strategies. Despite the potential fitness advantage of parasitism, facultative parasites continue to exhibit genetic variation in parasitic behaviour in nature. We hypothesized that evolutionary trade-offs associated with parasitic host-attachment behaviour maintain natural variation observed in attachment behaviour. In this study, we used replicate lines of a facultatively parasitic mite, previously selected for increased host-attachment behaviour to test whether increased attachment trades off with mite fecundity and longevity, as well as the phenotypic plasticity of attachment. We also tested for potential correlated changes in mite morphology. To test for context-dependent trade-offs, mite fecundity and longevity were assayed in the presence or absence of a host. Our results show that selected and control mites exhibited similar fecundities, longevities, attachment plasticities and morphologies, which did not provide evidence for life history trade-offs associated with increased attachment. Surprisingly, phenotypic plasticity in attachment was maintained despite directional selection on the trait, which suggests that phenotypic plasticity likely plays an important role in maintaining attachment variation in natural populations of this facultative parasite.

Life history of Macrocheles muscaedomesticae (Parasitiformes: Macrochelidae): new insights on life history and evidence of facultative parasitism on Drosophila.

Macrocheles muscaedomesticae is a cosmopolitan macrochelid mite whose populations have likely diverged considering the many locations they inhabit, but most of the work published on this mite species has been on the basis of their association with the house fly, Musca domestica. Here, we studied several aspects of the biology of M. muscaedomesticae associated with drosophilid flies collected in Alberta, Canada. We assessed the degree of divergence of our populations from others, compared their life history to other published populations and experimentally tested whether M. muscaedomesticae feeds on Drosophila hydei hosts by comparing the body mass of mites that attached to hosts to those that did not. There was no strong phylogenetic differentiation among any of the M. muscaedomesticae specimens, suggesting multiple recent introductions of this species to Canada. Compared to other populations, our mites exhibited lower fecundity, which may have been a result of the temperature or nematode-only diet in which they were maintained. Finally, mites that attached to hosts for 4 h weighed significantly more than those that did not. Without direct evidence for host tissue transfer to the mites, it is difficult to determine whether the mites are indeed feeding on their hosts while attached. However, the existing evidence for the costs fly hosts endure at the expense of these mites makes this relationship antagonistic.

Mechanisms underlying parasite infection: influence of host body mass and age on chewing louse distribution among brown-headed cowbirds.

Animal populations exhibit various patterns in ectoparasite distribution across different sexes and age classes, and numerous factors can potentially contribute to ectoparasite abundance and distribution. We examined the influence of host body size and age on the distribution of a chewing louse among brown-headed cowbirds. Differences in louse prevalence (males 62.9 ± 2.8%, females 47.5 ± 4.9%) and intensity (males 15.42 ± 1.51, females 9.04 ± 1.69) were primarily driven by differences in host body mass and not host sex. Larger birds had larger louse infra-populations, which likely translated into a lower risk of local extinction, a possible explanation for higher louse prevalence observed among larger birds. Among males, younger individuals showed higher louse prevalence (70.21 ± 4.72%) compared to older males (59.36 ± 3.59). We speculate that this pattern is likely driven by behavioural difference and not body size, with young males spending relatively more time foraging in large groups, increasing their risk of louse transmission. By examining the mechanisms that underlie the sex- and age-biased infections observed in natural populations, we can better identify the hosts most responsible for parasite transmission.

Reducing Blood Draws in Pediatric Patients With Solid Organ Injury Through Protocolized Transcutaneous Hemoglobin Monitoring.

BACKGROUND: Management of pediatric solid organ injuries continues to evolve, decreasing the need for serial hemoglobin measurements, repeat imaging, and operative intervention. Transcutaneous continuous hemoglobin monitoring (TCHM) has been shown to effectively monitor hemoglobin levels in children with solid organ trauma. METHODS: A 6-year, single-center, retrospective chart review was conducted of pediatric solid organ injury patients aged 30 days to <18 years admitted to a quaternary children's hospital following implementation of a highly protocolized TCHM system. A laboratory hemoglobin measurement was obtained at the time of diagnosis and additional measurements were determined based on injury grading. Adverse events were tracked and included: central or arterial line placement, blood product(s) administration, percutaneous embolization procedures, transfer to the pediatric ICU and operative intervention. RESULTS: A total of 97 patients met the inclusion criteria. Blood draws were significantly reduced following TCHM protocol implementation (3.0 [IQR 2.0-5.5] vs 2.0 [IQR 1.0-4.5], p 0.01) without a significant increase in blood product administration (p = 0.30), central or arterial line placement (p = 1), or operative intervention (p = 0.29). Length of stay was not impacted (p = 0.36). The rate of unplanned ICU transfers and percutaneous embolization procedures were too low for statistical evaluation. CONCLUSION: TCHM safely reduces the need for serial blood draws in pediatric trauma patients when utilized within a well-defined protocol for solid organ injury. Further studies are needed to evaluate the role of TCHM in shortening or eliminating hospital admission for low-grade solid organ injuries in children. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Single-center, retrospective chart review cohort study.

Pediatric Surgery from the Roads Less Traveled: Challenges, Communication, and Collaboration from a Community Nonteaching Hospital.

Unique challenges face pediatric surgeons at community-based nonteaching hospitals. Communication and collaboration among and between healthcare providers, hospital administrators, and quaternary referral programs is crucial for the success of these smaller hospitals as they care for children.

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.

Continuous hemoglobin monitoring in pediatric trauma patients with solid organ injury.

BACKGROUND/PURPOSE: Hemoglobin monitoring is required in pediatric trauma patients with solid organ injury. We hypothesized that noninvasive hemodynamic monitoring (NIHM) represents an effective, safe alternative to laboratory hemoglobin (LabHb) monitoring in clinically stable patients. METHODS: A retrospective cohort study was conducted regarding pediatric trauma patients (<18 years old) with blunt solid organ injury over six consecutive months. Continuous NIHM was initiated at the time of admission, and LabHb measurements were obtained per institutional guidelines. Measurements were correlated within two hours of assessment and patient outcomes were analyzed. RESULTS: Twenty-one patients met inclusion criteria and had evaluable data. Blunt trauma was the exclusive mechanism of injury, and mean injury severity score was 16.6 for the cohort. Bland Altman analysis showed an average deviation of 0.80 g/dL between NIHM and LabHb values for all data pairs. Measurement trends were highly correlated in patients with stable hemoglobin levels and those requiring blood transfusion. CONCLUSIONS: NIHM demonstrated clinically acceptable accuracy when following hemoglobin trends in the defined pediatric trauma patient population. Slight variances between NIHM and LabHb values were occasionally noted, but did not affect clinical management. Continuous NIHM represents a potentially valuable adjunct to traditional laboratory hemoglobin monitoring. LEVEL OF EVIDENCE RATING: IV.

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.

Pediatric blunt abdominal aortic injury and the use of intra-operative aortic ultrasound for surgical decision making.

Traumatic injury has been the most common cause of morbidity and mortality in the pediatric population, but injuries to the abdominal aorta are rare. We reviewed 2 children who underwent exploratory laparotomy for blunt aortic injury in which intra-operative ultrasound guided the surgical approach. Intra-operative ultrasound allowed us to minimize resection of normal aorta and achieve primary repair. In the pediatric population, achieving primary repair is ideal, as synthetic grafts will likely need future revisions as children grow. Here we present the use of intra-operative ultrasound in maximizing the chance at primary repair of the aorta following blunt injury.

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.

Commonly encountered surgical problems in the fetus and neonate.

Neonatal surgical care requires a current understanding of pre- and postnatal intervention for a myriad of congenital anomalies. This article includes an update of the recent information on commonly encountered fetal and neonatal surgical problems, highlighting specific areas of controversy and challenges in diagnosis. The authors hope that this article is useful for trainees and practitioners involved in any aspect of fetal and neonatal care.

The impact of work hour restrictions on surgical resident education.

OBJECTIVE: Resident work-hour restrictions were instituted in July 2003 based on ACGME mandates. The American Board of Surgery In-Training Examination (ABSITE), American Board of Surgery Qualifying Examination (ABSQE), and operative volume traditionally have been measures of surgical resident education and competency. The objective of this study was to determine the effect of reduced work hours on resident standardized test scores and operative volume at our institution. DESIGN: We reviewed ABSITE scores, ABSQE scores, and operative logs from 1997 to 2005 of all general surgery residents. Linear mixed-effects models were fitted for each component ABSITE score (total, basic science, and clinical management), and they were compared using a chi-squared likelihood ratio. Operative logs of graduating residents were compared before and after the work restrictions and were evaluated for association with ABSITE score. p-values less than 0.05 were considered significant. RESULTS: The program was compliant with ACGME mandates within 6 months of institution. ABSITE scores improved significantly after the restriction of work hours in both basic science (p = 0.003) and total score (p = 0.008). Clinical management scores were not affected. The number of major cases recorded by graduating residents did not change. A positive correlation was found between number of cases performed during residency and clinical management ABSITE scores (p = 0.045). ABSQE scores were not impacted by operative volume during residency. CONCLUSIONS: ABSITE scores improved significantly after the restriction of resident work hours. Resident operative experience was not affected. An unexpected consequence of work-hour restrictions may be an improvement in surgical resident education.