Lack of Routine Postoperative Labs Not Associated With Complications in Pediatric Perforated Appendicitis.

INTRODUCTION: Postoperative (postop) management of pediatric perforated appendicitis varies significantly, and postop intra-abdominal abscesses (IAA) remain a significant issue. Between 2019 and 2020, our standardized protocol included routine postop labs after an appendectomy for perforated appendicitis. However, given the lack of predictive utility of these routine labs, we discontinued this practice in 2021. We hypothesize that discontinuing routine postop labs will not be associated with an increase in complication rates after an appendectomy for pediatric perforated appendicitis. METHODS: A single-institution, retrospective review of all pediatric appendectomies for perforated appendicitis from January 2019 to December 2021 was conducted at University Hospitals Rainbow Babies and Children's Hospital in Cleveland, Ohio. Data were collected on rate of complications (IAA development, re-admissions, bowel obstructions, superficial surgical site infections, intensive care unit transfers, Clostridium difficile infections, allergic reactions, and transfusions), postop imaging, postop interventions, and length of stay. Statistical analysis was completed using Fisher's exact test and Mann-Whitney U-test. RESULTS: A total of 109 patients (2019-2020 n = 61, 2021 n = 48) were included in the study. All 61 patients from 2019 to 2020 had postop labs compared to only eight patients in 2021. There was no statistically significant difference between the two groups in overall complication rates, but there was a decrease in IAAs reported in 2021 (P = 0.03). There were no statistically significant differences in other complications, postop imaging usage, or postop interventions. The median length of stay was 4.5 d in 2021 compared to 6.0 d in 2019-2020 (P = 0.009). CONCLUSIONS: Discontinuing routine postop labs is not associated with an increase in overall complications rates. Further studies are needed to determine whether routine postop labs can be safely removed in pediatric patients with perforated appendicitis, which would reduce patient discomfort and care costs.

Labs Do Not Predict Postoperative Intra-abdominal Abscess in Pediatric Perforated Appendicitis.

INTRODUCTION: We aim to evaluate the utility of postoperative labs in predicting the development of an intra-abdominal abscess (IAA) in pediatric patients with perforated appendicitis. We hypothesize that postoperative labs are not predictive of IAA development. METHODS: This was a single-institution retrospective cohort study that included pediatric patients (n = 61) who underwent surgery for perforated appendicitis from January 1, 2019 to December 1, 2020. Patients were stratified into those who developed a postoperative IAA (n = 22) and those who did not (n = 39). Postoperative labs (white blood cell [WBC] count, absolute neutrophil count, platelet count, C-reactive protein) were examined. Mann-Whitney U tests and chi-square tests were used to assess for differences between groups. RESULTS: There was extensive heterogeneity and overlap in postoperative lab values between patients who developed an IAA and those who did not. Almost all patients who developed an IAA had clinical signs that were indicative of abscess formation regardless of their postoperative WBC count or change in WBC count. While patients who developed an IAA had a higher postoperative median WBC count (10.8 versus 8.4, P = 0.003) and a smaller WBC count decrease (-4.9 versus -7.4, P = 0.01), no cutoff value for any of the examined lab values specifically predicted abscess formation. Postoperative median absolute neutrophil count (7.4 versus 4.0, P = 0.15), platelet count (360 versus 353, P = 0.98), and C-reactive protein (8.20 versus 5.32, P = 0.06) did not differ significantly. CONCLUSIONS: We conclude that postoperative labs have limited clinical utility in evaluating IAA development in children with perforated appendicitis.

In vivo proximity labeling identifies cardiomyocyte protein networks during zebrafish heart regeneration.

Strategies have not been available until recently to uncover interacting protein networks specific to key cell types, their subcellular compartments, and their major regulators during complex in vivo events. Here, we apply BioID2 proximity labeling to capture protein networks acting within cardiomyocytes during a key model of innate heart regeneration in zebrafish. Transgenic zebrafish expressing a promiscuous BirA2 localized to the entire myocardial cell or membrane compartment were generated, each identifying distinct proteomes in adult cardiomyocytes that became altered during regeneration. BioID2 profiling for interactors with ErbB2, a co-receptor for the cardiomyocyte mitogen Nrg1, implicated Rho A as a target of ErbB2 signaling in cardiomyocytes. Blockade of Rho A during heart regeneration, or during cardiogenic stimulation by the mitogenic influences Nrg1, Vegfaa, or vitamin D, disrupted muscle creation. Our findings reveal proximity labeling as a useful resource to interrogate cell proteomes and signaling networks during tissue regeneration in zebrafish.

An array of 60,000 antibodies for proteome-scale antibody generation and target discovery.

Antibodies are essential for elucidating gene function. However, affordable technology for proteome-scale antibody generation does not exist. To address this, we developed Proteome Epitope Tag Antibody Library (PETAL) and its array. PETAL consists of 62,208 monoclonal antibodies (mAbs) against 15,199 peptides from diverse proteomes. PETAL harbors binders for a great multitude of proteins in nature due to antibody multispecificity, an intrinsic antibody feature. Distinctive combinations of 10,000 to 20,000 mAbs were found to target specific proteomes by array screening. Phenotype-specific mAb-protein pairs were found for maize and zebrafish samples. Immunofluorescence and flow cytometry mAbs for membrane proteins and chromatin immunoprecipitation-sequencing mAbs for transcription factors were identified from respective proteome-binding PETAL mAbs. Differential screening of cell surface proteomes of tumor and normal tissues identified internalizing tumor antigens for antibody-drug conjugates. By finding high-affinity mAbs at a fraction of current time and cost, PETAL enables proteome-scale antibody generation and target discovery.