John Densmore | Medical College of Wisconsin (original) (raw)

Papers by John Densmore

Research paper thumbnail of Initial surgical and pain management outcomes after Nuss procedure

Journal of Pediatric Surgery, Sep 1, 2010

The purpose of this article was to report surgical and pain management outcomes of the initial Nu... more The purpose of this article was to report surgical and pain management outcomes of the initial Nuss procedure experience at the Children's Hospital of Wisconsin (Milwaukee) and to place this experience in the context of the published literature. Methods: The initial 118 consecutive Nuss procedures in 117 patients were retrospectively reviewed with approval of the Children's Hospital of Wisconsin human rights review board. Patient, surgical, complication, and pain descriptors were collected for each case. Statistical methods for comparison of pain strategies included the Kolmogorov-Smirnov test for normality, 1-way repeated measures analysis of variance, and paired t tests. Results: Patient, surgical, and complication descriptors were comparable to other large series. Complication rates were 7% early and 25% late. Epidural success rate was 96.4%. There was 1 episode of recurrence 2 years postbar removal (n = 114). Conclusions: The institution of the Nuss procedure provides a highly desired result with significant complication rates. The ideal approach would deliver this result with lower risk. A pain service-driven epidural administration of morphine or hydromorphone with local anesthetic provides excellent analgesia for patients after Nuss procedure. The success of epidural analgesia is independent of catheter site and adjunctive medications. Ketorolac was an effective breakthrough medication.

Research paper thumbnail of An Evaluation of Medium-term Outcomes of Thoracoscopic Congenital Diaphragmatic Hernia Repair in Neonates and Infants

Journal of Surgical Research, Feb 1, 2012

Research paper thumbnail of Variability in the Method of Gastrostomy Placement in Children

Children, 2020

Although gastrostomy placement is one of the most common procedures performed in children, the op... more Although gastrostomy placement is one of the most common procedures performed in children, the optimal technique remains unclear. The purpose of this study was to evaluate variability in the method of gastrostomy tube placement in children in the United States. Patients <18 years old undergoing percutaneous endoscopic gastrostomy (PEG) or surgical gastrostomy (SG) (including open or laparoscopic) from 1997 to 2012 were identified using the Kids’ Inpatient Database. Method of gastrostomy placement was evaluated using a multivariable mixed-effects logistic regression model with a random intercept term and a patient-age random-effect term. A total of 67,811 gastrostomy placements were performed during the study period. PEG was used in 36.6% of entries overall and was generally consistent over time. PEG placement was less commonly performed in infants (adjusted odds ratio [aOR] 0.30, 95%CI 0.26–0.33), children at urban hospitals (aOR: 0.38, 95%CI 0.18–0.82), and children cared for at...

Research paper thumbnail of The incidence of venous thromboembolism in children following colorectal resection for inflammatory bowel disease: A multi-center study

Journal of Pediatric Surgery, 2020

Background/Purpose Children with inflammatory bowel disease (IBD) have increased risk for venous ... more Background/Purpose Children with inflammatory bowel disease (IBD) have increased risk for venous thromboembolism (VTE). We sought to determine incidence and risk factors for postoperative VTE in a multicenter cohort of pediatric patients undergoing colorectal resection for IBD. Methods Retrospective review of children ≤18yrs who underwent colorectal resection for IBD from 2010-2016 was performed at four children's hospitals. Primary outcome was VTE that occurred between surgery and last follow-up. Factors associated with VTE were determined using univariable and multivariable analyses. Results Two-hundred-and-seventy-six patients were included with median age 15yrs [13,17]. Forty-two children (15%) received perioperative VTE chemoprophylaxis, and 88 (32%) received mechanical prophylaxis. DVT occurred in 12 patients (4.3%) at a median of 14 days postoperatively [8,147]. Most were portomesenteric (n=9, 75%) with the remaining catheter-associated DVTs in extremities (n=3, 25%). There was no association with chemoprophylaxis (p>0.99). On Cox regression, emergent procedure [HR 18.8, 95%CI: 3.18-111], perioperative plasma transfusion [HR 25.1, 95%CI: 2.4-259], and postoperative infectious complication [HR 10.5, 95%CI: 2.63-41.8] remained predictive of DVT. Conclusion Less than 5% of pediatric IBD patients developed postoperative VTE. Chemoprophylaxis was not protective but rarely used. Patients with risk factors identified in this study should be monitored or given prophylaxis for VTE.

Research paper thumbnail of Lung injury pathways: Adenosine receptor 2B signaling limits development of ischemic bronchiolitis obliterans organizing pneumonia

Experimental lung research, Feb 1, 2017

Purpose/Aim of the Study: Adenosine signaling was studied in bronchiolitis obliterans organizing ... more Purpose/Aim of the Study: Adenosine signaling was studied in bronchiolitis obliterans organizing pneumonia (BOOP) resulting from unilateral lung ischemia. Ischemia was achieved by either left main pulmonary artery or complete hilar ligation. Sprague-Dawley (SD) rats, Dahl salt sensitive (SS) rats and SS mutant rat strains containing a mutation in the A2B adenosine receptor gene (Adora2b) were studied. Adenosine concentrations were measured in bronchoalveolar lavage (BAL) by HPLC. A2A (A2AAR) and A2B adenosine receptor (A2BAR) mRNA and protein were quantified. Twenty-four hours after unilateral PA ligation, BAL adenosine concentrations from ischemic lungs were increased relative to contralateral lungs in SD rats. A2BAR mRNA and protein concentrations were increased after PA ligation while miR27a, a negatively regulating microRNA, was decreased in ischemic lungs. A2AAR mRNA and protein concentrations remained unchanged following ischemia. A2BAR protein was increased in PA ligated lung...

Research paper thumbnail of Mitochondria-Regulated Formation of Endothelial Extracellular Vesicles Shifts the Mediator of Flow-Induced Vasodilation

American journal of physiology. Heart and circulatory physiology, Jan 17, 2017

In order to examine the effect of endothelial-derived extracellular vesicles (eEVs) on the mechan... more In order to examine the effect of endothelial-derived extracellular vesicles (eEVs) on the mechanism of flow-induced dilation (FID) composition, formation, and functional effects on the mechanism of FID were examined from two different eEV subtypes, one produced from ceramide, the other from plasminogen-activator inhibitor 1 (PAI-1). Using videomicroscopy, internal diameter changes in response to increases in flow were measured in human adipose resistance arteries acutely exposed (30min) to eEVs derived from cultured endothelial cells exposed to ceramide or PAI-1. FID was significantly impaired following exposure to 500K/mL (K=1000) of ceramide-induced eEVs (Cer-eEVs) but unaffected by 250K/mL. FID was reduced in the presence of PEG-catalase following administration of 250K/mL of Cer-eEVs and PAI-1 eEVs whereas Nω-Nitro-L-arginine methyl ester (ʟ-NAME) had no effect. Pathway analysis following protein composition examination using liquid chromatography tandem mass spectrometry (LC M...

Research paper thumbnail of 99MTc-Hexamethylpropyleneamine Oxime Imaging for Early Detection of Acute Lung Injury in Rats Exposed to Hyperoxia or Lipopolysaccharide Treatment

Shock, 2016

99m Tc-Hexamethylpropyleneamine oxime (HMPAO) is a clinical single-photon emission computed tomog... more 99m Tc-Hexamethylpropyleneamine oxime (HMPAO) is a clinical single-photon emission computed tomography biomarker of tissue oxidoreductive state. Our objective was to investigate whether HMPAO lung uptake can serve as a pre-clinical marker of lung injury in two wellestablished rat models of human acute lung injury (ALI). Rats were exposed to >95% O 2 (hyperoxia) or treated with intratracheal lipopolysaccharide (LPS), with first endpoints obtained 24 hours later. HMPAO was administered intravenously before and after treatment with the glutathione-depleting agent diethyl maleate (DEM), scintigraphy images were acquired, and HMPAO lung uptake was quantified from the images. We also measured breathing rates, heart rates, oxygen saturation, bronchoalveolar lavage (BAL) cell counts and protein, lung homogenate glutathione (GSH) content, and pulmonary vascular endothelial filtration coefficient (K f). For hyperoxia rats, HMPAO lung uptake increased after 24 hours (134%) and 48 hours (172%) of exposure. For LPS-treated rats, HMPAO lung uptake increased (188%) 24 hours after injury and fell with resolution of injury. DEM reduced HMPAO uptake in hyperoxia and LPS rats by a greater fraction than in normoxia rats. Both hyperoxia exposure (18%) and LPS treatment (26%) increased lung homogenate GSH content, which correlated strongly with HMPAO uptake. Neither of the treatments had an effect on K f at 24 hours. LPS-treated rats appeared healthy but exhibited mild tachypnea, BAL and histological evidence of inflammation, and increased wet and dry lung

Research paper thumbnail of <title>Laser-induced fluorescence in the detection of esophageal carcinoma</title>

Optical Biopsy and Fluorescence Spectroscopy and Imaging, 1995

Research paper thumbnail of Hypoxia preconditioning increases survival and decreases expression of Toll-like receptor 4 in pulmonary artery endothelial cells exposed to lipopolysaccharide

Pulmonary circulation, 2013

Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes o... more Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) produ...

Research paper thumbnail of Rattus Model Utilizing Selective Pulmonary Ischemia Induces Bronchiolitis Obliterans Organizing Pneumonia

Shock, 2013

Background-Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associat... more Background-Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associated with lung transplant and chronic lung disease, is believed to be a complication of ischemia. Our goal was to develop a simple and reliable model of lung ischemia in the Sprague-Dawley rat that would produce BOOP. Methods-Unilateral ischemia without airway occlusion was produced by an occlusive slipknot placed around the left main pulmonary artery. Studies were performed 7 days later. Relative pulmonary and systemic flow to each lung was measured by injection of 99m Tc-macroaggregated albumin. Histological sections were examined for structure and necrosis and scored for BOOP. Apoptosis was detected by immunohistochemistry with an antibody against cleaved caspase-3. Results-Pulmonary artery blood flow to left lungs was <0.1% of the cardiac output, and bronchial artery circulation was ~2% of aortic artery flow. Histological sections from ischemic left lungs consistently showed Masson bodies, inflammation and young fibroblasts filling the distal airways and alveoli, consistent with BOOP. Quantitative evaluation of BOOP using epithelial changes, inflammation and fibrosis were higher in ischemic left lungs than right or sham-operated left lungs. Apoptosis was increased in areas exhibiting histological BOOP, but there was no histological evidence of necrosis. TLR4 expression was increased in ischemic left lungs over right. Conclusions-An occlusive slipknot around the main left PA in rats produces BOOP, providing direct evidence that ischemia without immunomodulation or coinfection is sufficient to initiate this injury. It also affords an excellent model to study signaling and genetic mechanisms underlying BOOP.

Research paper thumbnail of Risk of incomplete pyloromyotomy and mucosal perforation in open and laparoscopic pyloromyotomy

Journal of Pediatric Surgery, 2014

Background: Despite randomised controlled trials and meta-analyses, it remains unclear whether la... more Background: Despite randomised controlled trials and meta-analyses, it remains unclear whether laparoscopic pyloromyotomy (LP) carries a higher risk of incomplete pyloromyotomy and mucosal perforation compared with open pyloromyotomy (OP). Methods: Multicentre study of all pyloromyotomies (May 2007-December 2010) at 9 high volume institutions. The effect of laparoscopy on the procedure related complications of incomplete pyloromyotomy and mucosal perforation was determined using binomial logistic regression adjusting for differences among centres. Results: Data relating to 2830 pyloromyotomies (1802 [64%] LP) were analysed. There were 24 cases of incomplete pyloromyotomy; 3 in the open group (0.29%) and 21 in the laparoscopic group (1.16%). There were 18 cases of mucosal perforation; 3 in the open group (0.29%) and 15 in the laparoscopic group (0.83%). The regression model demonstrated that LP was a marginally significant predictor of incomplete pyloromyotomy (adjusted difference 0.87% [95%CI 0.006-4.083]; P=0.046) but not of mucosal perforation (adjusted difference 0.56% [95%CI-0.096-3.365]; P=0.153). Trainees performed a similar proportion of each procedure (laparoscopic 82.6% vs. open 80.3%; P=0.2) and grade of primary operator did not affect the rate of either complication. Conclusions: This is one of the largest series of pyloromyotomy ever reported. Although laparoscopy is associated with a statistically significant increase in the risk of incomplete pyloromyotomy, the effect size is small and of questionable clinical relevance. Both OP and LP are associated with low rates of mucosal perforation and incomplete pyloromyotomy in specialist centres, whether trainee or consultant surgeons perform the procedure.

Research paper thumbnail of Initial surgical and pain management outcomes after Nuss procedure

Journal of Pediatric Surgery, 2010

The purpose of this article was to report surgical and pain management outcomes of the initial Nu... more The purpose of this article was to report surgical and pain management outcomes of the initial Nuss procedure experience at the Children's Hospital of Wisconsin (Milwaukee) and to place this experience in the context of the published literature. Methods: The initial 118 consecutive Nuss procedures in 117 patients were retrospectively reviewed with approval of the Children's Hospital of Wisconsin human rights review board. Patient, surgical, complication, and pain descriptors were collected for each case. Statistical methods for comparison of pain strategies included the Kolmogorov-Smirnov test for normality, 1-way repeated measures analysis of variance, and paired t tests. Results: Patient, surgical, and complication descriptors were comparable to other large series. Complication rates were 7% early and 25% late. Epidural success rate was 96.4%. There was 1 episode of recurrence 2 years postbar removal (n = 114). Conclusions: The institution of the Nuss procedure provides a highly desired result with significant complication rates. The ideal approach would deliver this result with lower risk. A pain service-driven epidural administration of morphine or hydromorphone with local anesthetic provides excellent analgesia for patients after Nuss procedure. The success of epidural analgesia is independent of catheter site and adjunctive medications. Ketorolac was an effective breakthrough medication.

Research paper thumbnail of Protein disulfide isomerase induces endothelial cell dysfunction

Journal of the American College of Surgeons, 2007

no difference was observed between right and left ventricular tissue cytokine levels.

Research paper thumbnail of Case report of a newborn with a posterior thoracic midline congenital hemangiopericytoma of the back

Journal of Pediatric Surgery, 2000

Research paper thumbnail of Laparoscopic-assisted transhiatal gastric transposition for long gap esophageal atresia in an infant

Journal of Pediatric Surgery, 2010

Previous reports describing laparoscopic-assisted transhiatal gastric transposition for long gap ... more Previous reports describing laparoscopic-assisted transhiatal gastric transposition for long gap esophageal atresia (LGEA) have focused on older infants (median age of 11 months). By performing this operation at an earlier age, patients may avoid esophagostomies or prolonged hospitalizations with nasoesophageal tubes. An additional benefit is the earlier introduction of oral feeds, which is likely to decrease the incidence of oral aversion and feeding difficulties. In this report, we describe our surgical technique for performing a laparoscopic-assisted gastric transposition in a 56-day-old former 36-week premature infant with LGEA.

Research paper thumbnail of Outcomes and delivery of care in pediatric injury

Purpose: To design effective pediatric trauma care delivery systems, it is important to correlate... more Purpose: To design effective pediatric trauma care delivery systems, it is important to correlate site of care with corresponding outcomes. Using a multistate administrative database, we describe recent patient allocation and outcomes in pediatric injury. Methods: The 2000 Kids' Inpatient Database, containing 2,516,833 inpatient discharge records from 27 states, was filtered by E-code to yield pediatric injury cases. Injury Severity Scores (ISSs) were derived for each discharge using ICDMAP-90 (Tri-Analytics, Inc, Forest Hill, MD). After weighting to estimate national trends, cases were grouped by age (0-10, N10-20 years), ISS (V15, N15), and National Association of Children's Hospitals and Related Institutions-designated site of care. Measured outcomes included mortality, length of stay, and total charges. Analysis was completed using Student's t test and v 2 . Results: Among 79,673 injury cases, mean age was 12.2 F 6.2 years and ISS was 7.4 F 7.6. Eighty-nine percent of injured children received care outside of children's hospitals. In the subgroup of patients aged 0 to 10 years with ISS of greater than 15, the mean ISS for adult hospitals and children's hospitals was not significantly different (18.9 F 9.1 vs. 19.4 F 9.3, P = .08). However, in-hospital mortality, length of stay, and charges were all significantly higher in adult hospitals ( P b .0001). Conclusions: Younger and more seriously injured children have improved outcomes in children's hospitals. Appropriate triage may improve outcomes in pediatric trauma. D

Research paper thumbnail of Sickle cell disease increases high mobility group box 1: a novel mechanism of inflammation

Blood, Jan 18, 2014

High mobility group box 1 (HMGB1) is a chromatin-binding protein that maintains DNA structure. On... more High mobility group box 1 (HMGB1) is a chromatin-binding protein that maintains DNA structure. On cellular activation or injury, HMGB1 is released from activated immune cells or necrotic tissues and acts as a damage-associated molecular pattern to activate Toll-like receptor 4 (TLR4). Little is known concerning HMGB1 release and TLR4 activity and their role in the pathology of inflammation of sickle cell disease (SCD). Circulating HMGB1 levels were increased in both humans and mice with SCD compared with controls. Furthermore, sickle plasma increased HMGB1-dependent TLR4 activity compared with control plasma. HMGB1 levels were further increased during acute sickling events (vasoocclusive crises in humans or hypoxia/reoxygenation injury in mice). Anti-HMGB1 neutralizing antibodies reduced the majority of sickle plasma-induced TLR4 activity both in vitro and in vivo. These findings show that HMGB1 is the major TLR4 ligand in SCD and likely plays a critical role in SCD-mediated inflamm...

Research paper thumbnail of ENDOTHELIUM-DERIVED MICROPARTICLES INDUCE ENDOTHELIAL DYSFUNCTION AND ACUTE LUNG INJURY

Shock, 2006

Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports corre... more Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports correlate elevated concentrations of endothelium-derived microparticles (EMPs) with diseases of endothelial dysfunction. Many of these diseases have ALI sequelae. We hypothesize that EMPs contribute to endothelial cell (EC) dysfunction and development of ALI. To test this hypothesis, we treated isolated vessels with EMPs and examined changes in vasodilation. Endothelial cell cultures were incubated with EMPs and examined for changes in stimulated nitric oxide (&NO) production and nitric oxide synthase (eNOS) activation. Finally, EMPs were injected into rats and mice and lungs examined for ALI. In both mouse and human ex vivo vessel preparations, we found a marked attenuation of endothelium-mediated vasodilation after EMP treatment (4 Â 10 6 /mL). This dysfunction was not corrected by pretreatment of EMPs with free radical scavengers. Coincubation of EMPs with EC cultures yielded a three-fold reduction in A23187-stimulated &NO release. Western analysis of these cells showed a corresponding decrease in eNOS phosphorylation at Ser1179 and a decrease in hsp90 association. Measurements of lung permeability, myeloperoxidase activity, and histology of EMPs-treated Brown Norway rats demonstrated pulmonary edema, neutrophil recruitment, and compromise of the endothelial-alveolar barrier as a second hit phenomenon. In C57BL/6 mice, exogenous EMPs caused a significant rise in pulmonary capillary permeability both as a primary and secondary injury. These findings demonstrate EMPs are capable of inducing significant lung injury at pathophysiologically relevant concentrations. Endothelium-derived microparticles inhibit endothelium-mediated vasodilation and &NO generation from eNOS. Once elucidated, EMP mechanisms of inducing ALI and endothelial dysfunction may present new therapeutic targets.

Research paper thumbnail of Clinical CVVH model removes endothelium-derived microparticles from circulation

Journal of Extracellular Vesicles, 2014

Background: Endothelium-derived microparticles (EMPs) are submicron vesicles released from the pl... more Background: Endothelium-derived microparticles (EMPs) are submicron vesicles released from the plasma membrane of endothelial cells in response to injury, apoptosis or activation. We have previously demonstrated EMP-induced acute lung injury (ALI) in animal models and endothelial barrier dysfunction in vitro. Current treatment options for ALI are limited and consist of supportive therapies. We hypothesize that standard clinical continuous venovenous hemofiltration (CVVH) reduces serum EMP levels and may be adapted as a potential therapeutic intervention. Materials and methods: EMPs were generated from plasminogen activation inhibitor-1 (PAI-1)-stimulated human umbilical vein endothelial cells (HUVECs). Flow cytometric analysis was used to characterize EMPs as CD31-and annexin V-positive events in a submicron size gate. Enumeration was completed against a known concentration of latex beads. Ultimately, a concentration of Â650,000 EMP/mL perfusate fluid (total 470 mL) was circulated through a standard CVVH filter (pore size 200 mm, flow rate 250 mL/hr) for a period of 70 minutes. 0.5 mL aliquots were removed at 5-to 10-minute intervals for flow cytometric analysis. EMP concentration in the dialysate was measured at the end of 4 hours to better understand the fate of EMPs. Results: A progressive decrease in circulating EMP concentration was noted using standard CVVH at 250 mL/hr (a clinical standard rate) from a 470 mL volume modelling a patient's circulation. A 50% reduction was noted within the first 30 minutes. EMPs entering the dialysate after 4 hours were 5.7% of the EMP original concentration. Conclusion: These data demonstrate that standard CVVH can remove EMPs from circulation in a circuit modelling a patient. An animal model of hemofiltration with induction of EMP release is required to test the therapeutic potential of this finding and potential of application in early treatment of ALI.

Research paper thumbnail of ENDOTHELIUM-DERIVED MICROPARTICLES INHIBIT HUMAN CARDIAC VALVE ENDOTHELIAL CELL FUNCTION

SHOCK, 2006

Elevated numbers of endothelium-derived microparticles (EMPs) in the circulation are found in a v... more Elevated numbers of endothelium-derived microparticles (EMPs) in the circulation are found in a variety of critical illnesses. EMPs have been associated with vascular dysfunction, including thrombotic complications and loss of normal vascular reactivity, common responses associated with cardiac valve injury. However, the exact mechanisms of this dysfunction and the potential impact on cardiac endothelium are unknown. We hypothesize that pathologic levels of circulating EMPs negatively regulate proliferation and migration of valvular endothelial cells (ECs), leading to downstream endothelial dysfunction. EMPs were generated from plasminogen activation inhibitor 1Ystimulated human umbilical vein endothelial cells (HUVECs). Human mitral valve endothelial cells (HMVECs) were isolated and characterized by platelet endothelial cellYderived adhesion moleculeY1 (PECAM-1, or CD31) and von Willebrand factor immunocytochemistry. HMVECs were treated with increasing EMP doses, and then, the effects of EMPs on growth factorYinduced proliferation and migration were tested. Proliferation was assessed by 3 H-thymidine incorporation. EC migration was assayed by photographing microtubules of HMVECs and HUVECs in fibrin gel incubated with EMPs T growth factors for 48 h. The EMP effects on nonvalve HUVECs were tested in parallel. EMPs inhibited HMVEC proliferation at high doses but stimulated HUVEC proliferation at all doses. In HMVECs, EMPs inhibited basic fibroblast growth factorY and vascular endothelial growth factorYinduced proliferation and migration. Taken together, these data suggest EMPs regulate valvular EC proliferation in a dose-dependent manner and, furthermore, modulate growth factor signaling in ECs. These results implicate EMPs as a possible source of downstream EC dysfunction in disease states. EMPs may play a role in valvular leaflet injury in human disease by inhibiting normal growth and repair of endothelium.

Research paper thumbnail of Initial surgical and pain management outcomes after Nuss procedure

Journal of Pediatric Surgery, Sep 1, 2010

The purpose of this article was to report surgical and pain management outcomes of the initial Nu... more The purpose of this article was to report surgical and pain management outcomes of the initial Nuss procedure experience at the Children's Hospital of Wisconsin (Milwaukee) and to place this experience in the context of the published literature. Methods: The initial 118 consecutive Nuss procedures in 117 patients were retrospectively reviewed with approval of the Children's Hospital of Wisconsin human rights review board. Patient, surgical, complication, and pain descriptors were collected for each case. Statistical methods for comparison of pain strategies included the Kolmogorov-Smirnov test for normality, 1-way repeated measures analysis of variance, and paired t tests. Results: Patient, surgical, and complication descriptors were comparable to other large series. Complication rates were 7% early and 25% late. Epidural success rate was 96.4%. There was 1 episode of recurrence 2 years postbar removal (n = 114). Conclusions: The institution of the Nuss procedure provides a highly desired result with significant complication rates. The ideal approach would deliver this result with lower risk. A pain service-driven epidural administration of morphine or hydromorphone with local anesthetic provides excellent analgesia for patients after Nuss procedure. The success of epidural analgesia is independent of catheter site and adjunctive medications. Ketorolac was an effective breakthrough medication.

Research paper thumbnail of An Evaluation of Medium-term Outcomes of Thoracoscopic Congenital Diaphragmatic Hernia Repair in Neonates and Infants

Journal of Surgical Research, Feb 1, 2012

Research paper thumbnail of Variability in the Method of Gastrostomy Placement in Children

Children, 2020

Although gastrostomy placement is one of the most common procedures performed in children, the op... more Although gastrostomy placement is one of the most common procedures performed in children, the optimal technique remains unclear. The purpose of this study was to evaluate variability in the method of gastrostomy tube placement in children in the United States. Patients <18 years old undergoing percutaneous endoscopic gastrostomy (PEG) or surgical gastrostomy (SG) (including open or laparoscopic) from 1997 to 2012 were identified using the Kids’ Inpatient Database. Method of gastrostomy placement was evaluated using a multivariable mixed-effects logistic regression model with a random intercept term and a patient-age random-effect term. A total of 67,811 gastrostomy placements were performed during the study period. PEG was used in 36.6% of entries overall and was generally consistent over time. PEG placement was less commonly performed in infants (adjusted odds ratio [aOR] 0.30, 95%CI 0.26–0.33), children at urban hospitals (aOR: 0.38, 95%CI 0.18–0.82), and children cared for at...

Research paper thumbnail of The incidence of venous thromboembolism in children following colorectal resection for inflammatory bowel disease: A multi-center study

Journal of Pediatric Surgery, 2020

Background/Purpose Children with inflammatory bowel disease (IBD) have increased risk for venous ... more Background/Purpose Children with inflammatory bowel disease (IBD) have increased risk for venous thromboembolism (VTE). We sought to determine incidence and risk factors for postoperative VTE in a multicenter cohort of pediatric patients undergoing colorectal resection for IBD. Methods Retrospective review of children ≤18yrs who underwent colorectal resection for IBD from 2010-2016 was performed at four children's hospitals. Primary outcome was VTE that occurred between surgery and last follow-up. Factors associated with VTE were determined using univariable and multivariable analyses. Results Two-hundred-and-seventy-six patients were included with median age 15yrs [13,17]. Forty-two children (15%) received perioperative VTE chemoprophylaxis, and 88 (32%) received mechanical prophylaxis. DVT occurred in 12 patients (4.3%) at a median of 14 days postoperatively [8,147]. Most were portomesenteric (n=9, 75%) with the remaining catheter-associated DVTs in extremities (n=3, 25%). There was no association with chemoprophylaxis (p>0.99). On Cox regression, emergent procedure [HR 18.8, 95%CI: 3.18-111], perioperative plasma transfusion [HR 25.1, 95%CI: 2.4-259], and postoperative infectious complication [HR 10.5, 95%CI: 2.63-41.8] remained predictive of DVT. Conclusion Less than 5% of pediatric IBD patients developed postoperative VTE. Chemoprophylaxis was not protective but rarely used. Patients with risk factors identified in this study should be monitored or given prophylaxis for VTE.

Research paper thumbnail of Lung injury pathways: Adenosine receptor 2B signaling limits development of ischemic bronchiolitis obliterans organizing pneumonia

Experimental lung research, Feb 1, 2017

Purpose/Aim of the Study: Adenosine signaling was studied in bronchiolitis obliterans organizing ... more Purpose/Aim of the Study: Adenosine signaling was studied in bronchiolitis obliterans organizing pneumonia (BOOP) resulting from unilateral lung ischemia. Ischemia was achieved by either left main pulmonary artery or complete hilar ligation. Sprague-Dawley (SD) rats, Dahl salt sensitive (SS) rats and SS mutant rat strains containing a mutation in the A2B adenosine receptor gene (Adora2b) were studied. Adenosine concentrations were measured in bronchoalveolar lavage (BAL) by HPLC. A2A (A2AAR) and A2B adenosine receptor (A2BAR) mRNA and protein were quantified. Twenty-four hours after unilateral PA ligation, BAL adenosine concentrations from ischemic lungs were increased relative to contralateral lungs in SD rats. A2BAR mRNA and protein concentrations were increased after PA ligation while miR27a, a negatively regulating microRNA, was decreased in ischemic lungs. A2AAR mRNA and protein concentrations remained unchanged following ischemia. A2BAR protein was increased in PA ligated lung...

Research paper thumbnail of Mitochondria-Regulated Formation of Endothelial Extracellular Vesicles Shifts the Mediator of Flow-Induced Vasodilation

American journal of physiology. Heart and circulatory physiology, Jan 17, 2017

In order to examine the effect of endothelial-derived extracellular vesicles (eEVs) on the mechan... more In order to examine the effect of endothelial-derived extracellular vesicles (eEVs) on the mechanism of flow-induced dilation (FID) composition, formation, and functional effects on the mechanism of FID were examined from two different eEV subtypes, one produced from ceramide, the other from plasminogen-activator inhibitor 1 (PAI-1). Using videomicroscopy, internal diameter changes in response to increases in flow were measured in human adipose resistance arteries acutely exposed (30min) to eEVs derived from cultured endothelial cells exposed to ceramide or PAI-1. FID was significantly impaired following exposure to 500K/mL (K=1000) of ceramide-induced eEVs (Cer-eEVs) but unaffected by 250K/mL. FID was reduced in the presence of PEG-catalase following administration of 250K/mL of Cer-eEVs and PAI-1 eEVs whereas Nω-Nitro-L-arginine methyl ester (ʟ-NAME) had no effect. Pathway analysis following protein composition examination using liquid chromatography tandem mass spectrometry (LC M...

Research paper thumbnail of 99MTc-Hexamethylpropyleneamine Oxime Imaging for Early Detection of Acute Lung Injury in Rats Exposed to Hyperoxia or Lipopolysaccharide Treatment

Shock, 2016

99m Tc-Hexamethylpropyleneamine oxime (HMPAO) is a clinical single-photon emission computed tomog... more 99m Tc-Hexamethylpropyleneamine oxime (HMPAO) is a clinical single-photon emission computed tomography biomarker of tissue oxidoreductive state. Our objective was to investigate whether HMPAO lung uptake can serve as a pre-clinical marker of lung injury in two wellestablished rat models of human acute lung injury (ALI). Rats were exposed to >95% O 2 (hyperoxia) or treated with intratracheal lipopolysaccharide (LPS), with first endpoints obtained 24 hours later. HMPAO was administered intravenously before and after treatment with the glutathione-depleting agent diethyl maleate (DEM), scintigraphy images were acquired, and HMPAO lung uptake was quantified from the images. We also measured breathing rates, heart rates, oxygen saturation, bronchoalveolar lavage (BAL) cell counts and protein, lung homogenate glutathione (GSH) content, and pulmonary vascular endothelial filtration coefficient (K f). For hyperoxia rats, HMPAO lung uptake increased after 24 hours (134%) and 48 hours (172%) of exposure. For LPS-treated rats, HMPAO lung uptake increased (188%) 24 hours after injury and fell with resolution of injury. DEM reduced HMPAO uptake in hyperoxia and LPS rats by a greater fraction than in normoxia rats. Both hyperoxia exposure (18%) and LPS treatment (26%) increased lung homogenate GSH content, which correlated strongly with HMPAO uptake. Neither of the treatments had an effect on K f at 24 hours. LPS-treated rats appeared healthy but exhibited mild tachypnea, BAL and histological evidence of inflammation, and increased wet and dry lung

Research paper thumbnail of <title>Laser-induced fluorescence in the detection of esophageal carcinoma</title>

Optical Biopsy and Fluorescence Spectroscopy and Imaging, 1995

Research paper thumbnail of Hypoxia preconditioning increases survival and decreases expression of Toll-like receptor 4 in pulmonary artery endothelial cells exposed to lipopolysaccharide

Pulmonary circulation, 2013

Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes o... more Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) produ...

Research paper thumbnail of Rattus Model Utilizing Selective Pulmonary Ischemia Induces Bronchiolitis Obliterans Organizing Pneumonia

Shock, 2013

Background-Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associat... more Background-Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associated with lung transplant and chronic lung disease, is believed to be a complication of ischemia. Our goal was to develop a simple and reliable model of lung ischemia in the Sprague-Dawley rat that would produce BOOP. Methods-Unilateral ischemia without airway occlusion was produced by an occlusive slipknot placed around the left main pulmonary artery. Studies were performed 7 days later. Relative pulmonary and systemic flow to each lung was measured by injection of 99m Tc-macroaggregated albumin. Histological sections were examined for structure and necrosis and scored for BOOP. Apoptosis was detected by immunohistochemistry with an antibody against cleaved caspase-3. Results-Pulmonary artery blood flow to left lungs was <0.1% of the cardiac output, and bronchial artery circulation was ~2% of aortic artery flow. Histological sections from ischemic left lungs consistently showed Masson bodies, inflammation and young fibroblasts filling the distal airways and alveoli, consistent with BOOP. Quantitative evaluation of BOOP using epithelial changes, inflammation and fibrosis were higher in ischemic left lungs than right or sham-operated left lungs. Apoptosis was increased in areas exhibiting histological BOOP, but there was no histological evidence of necrosis. TLR4 expression was increased in ischemic left lungs over right. Conclusions-An occlusive slipknot around the main left PA in rats produces BOOP, providing direct evidence that ischemia without immunomodulation or coinfection is sufficient to initiate this injury. It also affords an excellent model to study signaling and genetic mechanisms underlying BOOP.

Research paper thumbnail of Risk of incomplete pyloromyotomy and mucosal perforation in open and laparoscopic pyloromyotomy

Journal of Pediatric Surgery, 2014

Background: Despite randomised controlled trials and meta-analyses, it remains unclear whether la... more Background: Despite randomised controlled trials and meta-analyses, it remains unclear whether laparoscopic pyloromyotomy (LP) carries a higher risk of incomplete pyloromyotomy and mucosal perforation compared with open pyloromyotomy (OP). Methods: Multicentre study of all pyloromyotomies (May 2007-December 2010) at 9 high volume institutions. The effect of laparoscopy on the procedure related complications of incomplete pyloromyotomy and mucosal perforation was determined using binomial logistic regression adjusting for differences among centres. Results: Data relating to 2830 pyloromyotomies (1802 [64%] LP) were analysed. There were 24 cases of incomplete pyloromyotomy; 3 in the open group (0.29%) and 21 in the laparoscopic group (1.16%). There were 18 cases of mucosal perforation; 3 in the open group (0.29%) and 15 in the laparoscopic group (0.83%). The regression model demonstrated that LP was a marginally significant predictor of incomplete pyloromyotomy (adjusted difference 0.87% [95%CI 0.006-4.083]; P=0.046) but not of mucosal perforation (adjusted difference 0.56% [95%CI-0.096-3.365]; P=0.153). Trainees performed a similar proportion of each procedure (laparoscopic 82.6% vs. open 80.3%; P=0.2) and grade of primary operator did not affect the rate of either complication. Conclusions: This is one of the largest series of pyloromyotomy ever reported. Although laparoscopy is associated with a statistically significant increase in the risk of incomplete pyloromyotomy, the effect size is small and of questionable clinical relevance. Both OP and LP are associated with low rates of mucosal perforation and incomplete pyloromyotomy in specialist centres, whether trainee or consultant surgeons perform the procedure.

Research paper thumbnail of Initial surgical and pain management outcomes after Nuss procedure

Journal of Pediatric Surgery, 2010

The purpose of this article was to report surgical and pain management outcomes of the initial Nu... more The purpose of this article was to report surgical and pain management outcomes of the initial Nuss procedure experience at the Children's Hospital of Wisconsin (Milwaukee) and to place this experience in the context of the published literature. Methods: The initial 118 consecutive Nuss procedures in 117 patients were retrospectively reviewed with approval of the Children's Hospital of Wisconsin human rights review board. Patient, surgical, complication, and pain descriptors were collected for each case. Statistical methods for comparison of pain strategies included the Kolmogorov-Smirnov test for normality, 1-way repeated measures analysis of variance, and paired t tests. Results: Patient, surgical, and complication descriptors were comparable to other large series. Complication rates were 7% early and 25% late. Epidural success rate was 96.4%. There was 1 episode of recurrence 2 years postbar removal (n = 114). Conclusions: The institution of the Nuss procedure provides a highly desired result with significant complication rates. The ideal approach would deliver this result with lower risk. A pain service-driven epidural administration of morphine or hydromorphone with local anesthetic provides excellent analgesia for patients after Nuss procedure. The success of epidural analgesia is independent of catheter site and adjunctive medications. Ketorolac was an effective breakthrough medication.

Research paper thumbnail of Protein disulfide isomerase induces endothelial cell dysfunction

Journal of the American College of Surgeons, 2007

no difference was observed between right and left ventricular tissue cytokine levels.

Research paper thumbnail of Case report of a newborn with a posterior thoracic midline congenital hemangiopericytoma of the back

Journal of Pediatric Surgery, 2000

Research paper thumbnail of Laparoscopic-assisted transhiatal gastric transposition for long gap esophageal atresia in an infant

Journal of Pediatric Surgery, 2010

Previous reports describing laparoscopic-assisted transhiatal gastric transposition for long gap ... more Previous reports describing laparoscopic-assisted transhiatal gastric transposition for long gap esophageal atresia (LGEA) have focused on older infants (median age of 11 months). By performing this operation at an earlier age, patients may avoid esophagostomies or prolonged hospitalizations with nasoesophageal tubes. An additional benefit is the earlier introduction of oral feeds, which is likely to decrease the incidence of oral aversion and feeding difficulties. In this report, we describe our surgical technique for performing a laparoscopic-assisted gastric transposition in a 56-day-old former 36-week premature infant with LGEA.

Research paper thumbnail of Outcomes and delivery of care in pediatric injury

Purpose: To design effective pediatric trauma care delivery systems, it is important to correlate... more Purpose: To design effective pediatric trauma care delivery systems, it is important to correlate site of care with corresponding outcomes. Using a multistate administrative database, we describe recent patient allocation and outcomes in pediatric injury. Methods: The 2000 Kids' Inpatient Database, containing 2,516,833 inpatient discharge records from 27 states, was filtered by E-code to yield pediatric injury cases. Injury Severity Scores (ISSs) were derived for each discharge using ICDMAP-90 (Tri-Analytics, Inc, Forest Hill, MD). After weighting to estimate national trends, cases were grouped by age (0-10, N10-20 years), ISS (V15, N15), and National Association of Children's Hospitals and Related Institutions-designated site of care. Measured outcomes included mortality, length of stay, and total charges. Analysis was completed using Student's t test and v 2 . Results: Among 79,673 injury cases, mean age was 12.2 F 6.2 years and ISS was 7.4 F 7.6. Eighty-nine percent of injured children received care outside of children's hospitals. In the subgroup of patients aged 0 to 10 years with ISS of greater than 15, the mean ISS for adult hospitals and children's hospitals was not significantly different (18.9 F 9.1 vs. 19.4 F 9.3, P = .08). However, in-hospital mortality, length of stay, and charges were all significantly higher in adult hospitals ( P b .0001). Conclusions: Younger and more seriously injured children have improved outcomes in children's hospitals. Appropriate triage may improve outcomes in pediatric trauma. D

Research paper thumbnail of Sickle cell disease increases high mobility group box 1: a novel mechanism of inflammation

Blood, Jan 18, 2014

High mobility group box 1 (HMGB1) is a chromatin-binding protein that maintains DNA structure. On... more High mobility group box 1 (HMGB1) is a chromatin-binding protein that maintains DNA structure. On cellular activation or injury, HMGB1 is released from activated immune cells or necrotic tissues and acts as a damage-associated molecular pattern to activate Toll-like receptor 4 (TLR4). Little is known concerning HMGB1 release and TLR4 activity and their role in the pathology of inflammation of sickle cell disease (SCD). Circulating HMGB1 levels were increased in both humans and mice with SCD compared with controls. Furthermore, sickle plasma increased HMGB1-dependent TLR4 activity compared with control plasma. HMGB1 levels were further increased during acute sickling events (vasoocclusive crises in humans or hypoxia/reoxygenation injury in mice). Anti-HMGB1 neutralizing antibodies reduced the majority of sickle plasma-induced TLR4 activity both in vitro and in vivo. These findings show that HMGB1 is the major TLR4 ligand in SCD and likely plays a critical role in SCD-mediated inflamm...

Research paper thumbnail of ENDOTHELIUM-DERIVED MICROPARTICLES INDUCE ENDOTHELIAL DYSFUNCTION AND ACUTE LUNG INJURY

Shock, 2006

Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports corre... more Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports correlate elevated concentrations of endothelium-derived microparticles (EMPs) with diseases of endothelial dysfunction. Many of these diseases have ALI sequelae. We hypothesize that EMPs contribute to endothelial cell (EC) dysfunction and development of ALI. To test this hypothesis, we treated isolated vessels with EMPs and examined changes in vasodilation. Endothelial cell cultures were incubated with EMPs and examined for changes in stimulated nitric oxide (&NO) production and nitric oxide synthase (eNOS) activation. Finally, EMPs were injected into rats and mice and lungs examined for ALI. In both mouse and human ex vivo vessel preparations, we found a marked attenuation of endothelium-mediated vasodilation after EMP treatment (4 Â 10 6 /mL). This dysfunction was not corrected by pretreatment of EMPs with free radical scavengers. Coincubation of EMPs with EC cultures yielded a three-fold reduction in A23187-stimulated &NO release. Western analysis of these cells showed a corresponding decrease in eNOS phosphorylation at Ser1179 and a decrease in hsp90 association. Measurements of lung permeability, myeloperoxidase activity, and histology of EMPs-treated Brown Norway rats demonstrated pulmonary edema, neutrophil recruitment, and compromise of the endothelial-alveolar barrier as a second hit phenomenon. In C57BL/6 mice, exogenous EMPs caused a significant rise in pulmonary capillary permeability both as a primary and secondary injury. These findings demonstrate EMPs are capable of inducing significant lung injury at pathophysiologically relevant concentrations. Endothelium-derived microparticles inhibit endothelium-mediated vasodilation and &NO generation from eNOS. Once elucidated, EMP mechanisms of inducing ALI and endothelial dysfunction may present new therapeutic targets.

Research paper thumbnail of Clinical CVVH model removes endothelium-derived microparticles from circulation

Journal of Extracellular Vesicles, 2014

Background: Endothelium-derived microparticles (EMPs) are submicron vesicles released from the pl... more Background: Endothelium-derived microparticles (EMPs) are submicron vesicles released from the plasma membrane of endothelial cells in response to injury, apoptosis or activation. We have previously demonstrated EMP-induced acute lung injury (ALI) in animal models and endothelial barrier dysfunction in vitro. Current treatment options for ALI are limited and consist of supportive therapies. We hypothesize that standard clinical continuous venovenous hemofiltration (CVVH) reduces serum EMP levels and may be adapted as a potential therapeutic intervention. Materials and methods: EMPs were generated from plasminogen activation inhibitor-1 (PAI-1)-stimulated human umbilical vein endothelial cells (HUVECs). Flow cytometric analysis was used to characterize EMPs as CD31-and annexin V-positive events in a submicron size gate. Enumeration was completed against a known concentration of latex beads. Ultimately, a concentration of Â650,000 EMP/mL perfusate fluid (total 470 mL) was circulated through a standard CVVH filter (pore size 200 mm, flow rate 250 mL/hr) for a period of 70 minutes. 0.5 mL aliquots were removed at 5-to 10-minute intervals for flow cytometric analysis. EMP concentration in the dialysate was measured at the end of 4 hours to better understand the fate of EMPs. Results: A progressive decrease in circulating EMP concentration was noted using standard CVVH at 250 mL/hr (a clinical standard rate) from a 470 mL volume modelling a patient's circulation. A 50% reduction was noted within the first 30 minutes. EMPs entering the dialysate after 4 hours were 5.7% of the EMP original concentration. Conclusion: These data demonstrate that standard CVVH can remove EMPs from circulation in a circuit modelling a patient. An animal model of hemofiltration with induction of EMP release is required to test the therapeutic potential of this finding and potential of application in early treatment of ALI.

Research paper thumbnail of ENDOTHELIUM-DERIVED MICROPARTICLES INHIBIT HUMAN CARDIAC VALVE ENDOTHELIAL CELL FUNCTION

SHOCK, 2006

Elevated numbers of endothelium-derived microparticles (EMPs) in the circulation are found in a v... more Elevated numbers of endothelium-derived microparticles (EMPs) in the circulation are found in a variety of critical illnesses. EMPs have been associated with vascular dysfunction, including thrombotic complications and loss of normal vascular reactivity, common responses associated with cardiac valve injury. However, the exact mechanisms of this dysfunction and the potential impact on cardiac endothelium are unknown. We hypothesize that pathologic levels of circulating EMPs negatively regulate proliferation and migration of valvular endothelial cells (ECs), leading to downstream endothelial dysfunction. EMPs were generated from plasminogen activation inhibitor 1Ystimulated human umbilical vein endothelial cells (HUVECs). Human mitral valve endothelial cells (HMVECs) were isolated and characterized by platelet endothelial cellYderived adhesion moleculeY1 (PECAM-1, or CD31) and von Willebrand factor immunocytochemistry. HMVECs were treated with increasing EMP doses, and then, the effects of EMPs on growth factorYinduced proliferation and migration were tested. Proliferation was assessed by 3 H-thymidine incorporation. EC migration was assayed by photographing microtubules of HMVECs and HUVECs in fibrin gel incubated with EMPs T growth factors for 48 h. The EMP effects on nonvalve HUVECs were tested in parallel. EMPs inhibited HMVEC proliferation at high doses but stimulated HUVEC proliferation at all doses. In HMVECs, EMPs inhibited basic fibroblast growth factorY and vascular endothelial growth factorYinduced proliferation and migration. Taken together, these data suggest EMPs regulate valvular EC proliferation in a dose-dependent manner and, furthermore, modulate growth factor signaling in ECs. These results implicate EMPs as a possible source of downstream EC dysfunction in disease states. EMPs may play a role in valvular leaflet injury in human disease by inhibiting normal growth and repair of endothelium.