Edward J. Doolin

Collagen crosslinking and cell density have distinct effects on fibroblast-mediated contraction of collagen gels.

Background/purpose: Fibroblasts are actively and dynamically involved in wound healing (dermal regeneration, wound contraction, and scar contracture) and fibrosis. Fibroblast‐seeded collagen gels provide an in vitro model for these processes. Over time, fibroblasts will contract the gels, but the mechanisms are not completely understood. This research investigated the influence of cell density and collagen crosslinking on the contraction of fibroblast‐populated gels by varying seeding density and blocking the catalyzing enzyme lysyl oxidase, respectively.

Pharmacologic inhibition of collagen in an experimental model of subglottic stenosis

Subglottic stenosis occurs as a complication of prolonged endotracheal intubation secondary to inflammation with development of scar tissue and subsequent fibrosis. Collagen I and III levels increase during the healing process. Steroids alter the inflammatory response, decreasing recruitment of macrophages and fibroblasts. β-Aminopropionitrile (βAPN) inhibits the development of collagen cross-linking. A mechanism that would minimize hypertrophic scarring was sought. Eighteen dogs were anesthetized, had tracheostomies performed, and later had cautery of the mucosa and inner layer of the cricoid cartilage. Of 18 survivors, 6 animals were used as controls, 6 animals received oral Decadron, 2 mg/d, and 6 animals received oral βAPN, 40 mg/d. There were 9 early deaths — 5 in the steroid group. Animals were painlessly sacrificed, and the specimens were sectioned at the cricoid cartilage level and were stained immunohistochemically for antibodies to collagen types I to VI. Analysis of the area of scar and the intensity of stain was performed with Mocha image analysis software. Collagen III increased in control animals to 14.38 ± 1.85 (intensity stain index), but this reaction was reduced by βAPN (5.77 ± 1.78, p <.01). Steroids had no significant effect on formation of any type of collagen. Lathyrogens (βAPN) may offer a pharmacologic tool to reduce scar tissue.

Hepaticoduodenostomy vs hepaticojejunostomy for reconstruction after resection of choledochal cyst.

PURPOSE Roux-en-Y hepaticojejunostomy (HJ) is currently the favored reconstructive procedure after resection of choledochal cysts. Hepaticoduodenostomy (HD) has been argued to be more physiologically and technically easier but is feared to have associated complications. Here we compare outcomes of the 2 procedures. METHODS A retrospective chart review identified 59 patients who underwent choledochal cyst resection within our institution from 1999 to 2009. Demographic and outcome data were compared using t tests, Mann-Whitney U tests, and Pearson χ(2) tests. RESULTS Fifty-nine patients underwent repair of choledochal cyst. Biliary continuity was restored by HD in 39 (66%) and by HJ in 20 (34%). Open HD patients required less total operative time than HJ patients (3.9 vs 5.1 hours, P = .013), tolerated a diet faster (4.8 days compared with 6.1 days, P = .08), and had a shorter hospital stay (7.05 days for HD vs 9.05 days for HJ, P = .12). Complications were more common in HJ (HD = 7.6%, HJ = 20%, P = .21). Three patients required reoperation after HJ, but only one patient required reoperation after HD for a stricture (HD = 2.5%, HJ = 20%, P = .037). CONCLUSIONS In this series, HD required less operative time, allowed faster recovery of bowel function, and produced fewer complications requiring reoperation.

Calibration of Endoscopic Images

In pediatric airway surgery, endoscopic evaluation of the lesions and treatment is important. However, there are no objective and reproducible methods for measurement. The purpose of this study was to define the optical effects of a Storz-Hopkins system and develop a method of calibration and measurement. Known geometric images (grids and circles) were viewed through the Storz-Hopkins system and recorded. These images were then analyzed morphometrically with a computer image analyzer (Jandel Scientific). The distortion of the endoscope could be identified, and the severity was found to be a function of the distance from the center of the field (r = .962). When this distortion factor (range, 0% to 25% shrinkage) was used mathematically, known circles could be measured by means of an endoscopic image. The error was reduced from 17.6% to 4.3% (p < .003). With morphometric programs the optical distortion of the bronchoscope can be calibrated. This can then be used to correct the measurement of images.

Motility abnormality in intestinal atresia

This study was designed to investigate the motility of the small bowel of the lamb under the conditions of experimental intestinal atresia. Of 26 fetal lambs operated upon (50 to 90 days gestation), 13 came to term. All term lambs exhibited a type 3a atresia. Six were successfully repaired and had intestinal myoelectric activity monitored for periods from 2 to 27 hours. A slow wave pattern (12 to 13/min) was present in the bowel of control lambs and in the proximal dilated bowel and the microbowel of atretic lambs, confirming the presence of functional smooth muscle. Spike potentials, which indicated circular muscular contractions, occurred 10% of the time in the control intestine, 5% in the proximal dilated gut (P less than .2), and 0% in the microbowel (P less than .001). A previously undescribed myoelectric transient of variable amplitude and frequency (6 to 24/min) was identified in all lambs studied. Histologic evaluation demonstrated villous hyperplasia in the microbowel and mucosal flattening in the distended bowel. The data suggest that the quiescent microbowel distal to the atresia contributes significantly to the functional obstruction.

Pediatric trauma center criteria: An outcomes analysis

BACKGROUND/PURPOSE Trauma centers (TC) are certified based on widely accepted criteria. These specific criteria rarely are scrutinized individually. The purpose of this study was to analyze the individual components of a pediatric trauma center for their effect on outcome. METHODS Members of the National Pediatric Trauma Registry were queried about the following: (1) separate pediatric emergency department (ED), (2) pediatric intensive care unit (PICU), (3) pediatric intensivist as PICU director, (4) pediatric surgeon as TC director, (5) in-house attending surgeon, (6) in-house pediatric emergency physician, (7) 24-hour operating room, (8) 24-hour computed tomography (CT) scan. Outcomes analyzed included mortality, length of stay, time in ED, days in PICU, and disability. Victims were stratified based on age (<7 or > or = 7 years) and severity of injury (ISS < or = 16, 17-35, > or = 36). Results were compared using Students t test and chi2 analysis. RESULTS A total of 59 of 74 centers responded, 18 were dropped because of low enrollment (mean, 1.6 patients). Questions 3, 4, 6, and 7 were eliminated because of skewed data. An in-house surgeon reduced the amount of time a mildly injured patient (ISS < or = 16) spent in the ED (210 v434 minutes), as did the separate pediatric ED (333 v592 minutes) and pediatric emergency physicians (344 v 507 minutes) in younger patients (> or = 7 years). An in-house surgeon reduced the morality rate in older (> or = 7) severely injured (ISS > or = 36) patients (46.7% v 56.8%; P < .05 for all). No other differences were significant. CONCLUSIONS In-house personnel improved efficiency for the less severely injured, and an in-house attending surgeon reduced mortality in the severely injured older patient. None of the other variables were found to have a significant impact on outcome.

Single-stage versus multi-stage pull-through for Hirschsprung's disease: practice trends and outcomes in infants.

PURPOSE The aim of this study was to evaluate surgical treatments and outcomes in a multi-institutional cohort of neonates with Hirschsprungs disease (HD). METHODS Using the Pediatric Health Information System (PHIS) from 1999 to 2009, neonates diagnosed with HD were identified and classified as having a single stage pull-through (SSPT) or multi-stage pull-through (MSPT). Diagnosis and classification algorithms and clinical variables and outcomes were validated by multi-institutional chart review. Groups were compared using logistic regression modeling and propensity-score matched analysis to account for baseline differences between groups. RESULTS 1555 neonates with HD were identified; 77.2% underwent SSPT and 22.8% underwent MSPT. Misclassification of disease or surgical treatment was <2%. Rates of SSPT increased over time (p=0.03). Compared to SSPT, patients undergoing MSPT had significantly lower birth weights and higher rates of prematurity, non-HD gastrointestinal anomalies, enterocolitis, and preoperative mechanical ventilation. Patients undergoing MSPT had significantly higher rates of readmissions (58.5 vs. 37.9%) and additional operations (38.7 vs. 26%). Results were consistent in the propensity-score matched analysis. CONCLUSION Most neonates with HD undergo SSPT. In patients with similar observed baseline characteristics, MSPT was associated with worse outcomes suggesting that some infants currently selected to undergo MSPT may have better outcomes with SSPT. However, there remains a subgroup of MSPT patients who were too ill to be adequately compared to SSPT patients; for this subgroup of severely ill infants with HD, MSPT may be the best option.

In vitro bioartificial skin culture model of tissue rejection and inflammatory/immune mechanisms☆

We hypothesized that an in vitro bioartificial skin rejection model using living LSEs grown in tissue culture could be developed for the study of autologous, allogenic, and/or xenogeneic inflammatory/immune mechanisms and topical immunosuppressive drugs. Human fibroblasts were mixed with type 1 rat-tail collagen to form a matrix (4 to 5 days), on which human keratinocytes were seeded. After a keratinocyte monolayer formed, CT cultures were raised to the air-liquid interface for continued growth. In the REJ LSE model, immunocytes isolated from human blood were seeded on top of the NHEK monolayer at the time of air-lifting. Thickness measurements of the acellular keratin and keratinocyte layers, and nuclear/cytoplasmic ratios, in both CT and REJ were made using digital image analysis. Immunostaining with anticytokeratin demonstrated a viable, keratin-producing epidermal layer; staining with anti-TGF-beta suggested a role for this cytokine in the rejection or wound-healing process. The LSE appeared histologically similar to normal human epidermis. Immunocytes added to the REJ cultures caused an obvious rejection response and were clearly identifiable in the gels as CD45+ staining cells. The LSE model appears promising for the study of immune/inflammatory mechanisms, thermal injury, screening antirejection agents that might be applied topically and as an in vitro replacement for skin graft studies in animals.

Airway measurement using morphometric analysis

Measurement of airway size using endoscopic morphometry was investigated. Endoscopic images of the porcine tracheobronchial tree were obtained via a Storz system at a known distance from the telescope. The bronchi were marked with transluminal wires, transected, and imaged. All images were analyzed morphometrically with a computer image at multiple sites (N = 20). The endoscopic measurements were plotted against the macro lens images so that a straight line with a slope of 1 would indicate a consistent correlation. Area measurements for all images had a slope of 0.67 (r = .885); however, for images with area < 80 mm2 the slope was 1 (r = .928) and for images with area > 80 mm2 the slope was −0.63 (r = .757). Minor axis measurements had a slope for all images of 0.71 (r = .879), for images with area < 80 mm2 of 0.93 (r = .875), and for images with area > 80 mm2 of −0.34 (r = .482), and major axis had a slope for all images of 0.73 (r = .904), for images with area < 80 mm2 of 0.88 (r = .923), and for images with area > 80 mm2 of−0.59 (r = .771). Accurate area measurements as well as major and minor axis measurements can be obtained for airways with area < 80 mm2 by means of this system. Each bronchoscope-telescope unit has an optimal target size for which measurements are accurate.

Familial retroperitoneal fibrosis.

Retroperitoneal fibrosis is an unusual cause of obstructive uropathy in the pediatric population. The etiology is unknown although there are laboratory and clinical associations with various autoimmune diseases. Familial associations have not been reported in children. A family is reported where two siblings have idiopathic retroperitoneal fibrosis. In addition, these sisters and the father manifest clinical laboratory evidence for systemic immunologic diseases. These young girls represent the first patients to illustrate both autoimmune and familial characteristics of this disease. These cases support the concept that retroperitoneal fibrosis is a local manifestation of a systemic immune disease.