Faculty Bibliography

OBJECTIVES/OBJECTIVE:Observational data to support delaying elective pediatric thoracic surgery during peak respiratory viral illness season is lacking. This study evaluated whether lung surgery during peak viral season is associated with differences in postoperative outcomes and resource utilization. METHODS:A retrospective observational cohort study was performed using the Pediatric Health Information System (PHIS). Patients with a congenital lung malformation (CLM) who underwent elective lung resection between 1 January 2016 and 29 February 2020 were included. Respiratory syncytial virus (RSV) incidence was used as a proxy for respiratory viral illness circulation. Monthly hospital-specific RSV incidence was calculated from PHIS data, and peak RSV season was defined by Centers for Disease Control data. Multivariable regression models were built to identify predictors of postoperative mechanical ventilation, which was the main outcome measure, as well as secondary outcomes including 30-day readmission after lung resection, postoperative length of stay (LOS) and hospital billing charges. RESULTS:Of 1542 CLM patients identified, 344 (22.3%) underwent lung resection during peak RSV season. 38% fewer operations were performed per month during peak RSV season than during off-peak months (p < .001). Children who underwent surgery during peak RSV season did not differ from the off-peak group in terms of age at operation, race, or comorbid conditions (i.e., congenital heart disease, newborn respiratory distress, and preoperative pneumonia). There was no association between hospital-specific RSV incidence at the time of surgery and postoperative mechanical ventilation, postoperative LOS, 30-day readmission rate or hospital billing charges. DISCUSSION/CONCLUSIONS:Performing elective lung surgery in children with CLMs during peak viral season is not associated with adverse surgical outcomes or increased utilization of healthcare resources.

Ovarian tumors are rare in children; however, their incidence increases with age. Of these ovarian tumors, Leydig cell tumors are some of the rarest, accounting for less than 0.1% of all ovarian tumors across all ages. Leydig cell tumors predominantly occur in postmenopausal women and are characterized by nodular proliferation of Leydig cells in the ovarian hilum with intracytoplasmic Reinke crystals. These tumors secrete androgens, which can disrupt ovarian function, clinically presenting with abnormal uterine bleeding and virilization. Although they are generally benign, current recommendations are for treatment with a unilateral salpingo-oophorectomy. In adolescents, hyperandrogenism is most commonly caused by polycystic ovarian syndrome (PCOS); however, the differential for hyperandrogenism is broad. We present a case of a 15-year-old girl with a history of primary amenorrhea who presented with a Leydig cell tumor associated with recurrent ovarian torsion and virilization. This case reviews the challenges with diagnosis, management, and future implications of a rare androgen-secreting tumor in young patients.

Protein translational control is critical for ensuring that the fetus develops correctly and that necessary organs and tissues are formed and functional. We developed an in utero method to quantify tissue-specific protein dynamics by monitoring amino acid incorporation into the proteome after pulse injection. Fetuses of pregnant mice were injected with isotopically labeled lysine and arginine via the vitelline vein at various embyonic days, and organs and tissues were harvested. By analyzing the nascent proteome, unique signatures of each tissue were identified by hierarchical clustering. In addition, the quantified proteome-wide turnover rates were calculated between 3.81E-5 and 0.424 h^-1. We observed similar protein turnover profiles for analyzed organs (e.g., liver vs. brain); however, their distributions of turnover rates vary significantly. The translational kinetic profiles of developing organs displayed differentially expressed protein pathways and synthesis rates, which correlated with known physiological changes during mouse development.

Protein translational control is highly regulated step in the gene expression program during mammalian development that is critical for ensuring that the fetus develops correctly and that all of the necessary organs and tissues are formed and functional. Defects in protein expression during fetal development can lead to severe developmental abnormalities or premature death. Currently, quantitative techniques to monitor protein synthesis rates in a developing fetus (in utero) are limited. Here, we developed a novel in utero stable isotope labeling approach to quantify tissue-specific protein dynamics of the nascent proteome during mouse fetal development. Fetuses of pregnant C57BL/6J mice were injected with isotopically labeled lysine (Lys8) and arginine (Arg10) via the vitelline vein at various gestational days. After treatment, fetal organs/tissues including brain, liver, lung, and heart were harvested for sample preparation and proteomic analysis. We show that the mean incorporation rate for injected amino acids into all organs was 17.50 ± 0.6%. By analyzing the nascent proteome, unique signatures of each tissue were identified by hierarchical clustering. In addition, the quantified proteome-wide turnover rates (k_obs) were calculated between 3.81E-5 and 0.424 hour^-1. We observed similar protein turnover profiles for analyzed organs (e.g., liver versus brain), however, their distributions of turnover rates vary significantly. The translational kinetic profiles of developing organs displayed differentially expressed protein pathways and synthesis rates which correlated with known physiological changes during mouse development.

In utero hematopoietic cell transplantation (IUHCT) is an experimental treatment for congenital hemoglobinopathies, including Sickle cell disease and thalassemias. One of the principal advantages of IUHCT is the predisposition of the developing fetus toward immunologic tolerance. This allows for engraftment across immune barriers without immunosuppression and, potentially, decreased susceptibility to graft-versus-host disease (GVHD). We demonstrate fetal resistance to GVHD following T cell-replete allogeneic hematopoietic cell transplantation compared with the neonate. We show that this resistance is associated with elevated fetal serum interleukin-10 conducive to the induction of regulatory T cells (Tregs). Finally, we demonstrate that the adoptive transfer of Tregs from IUHCT recipients to neonates uniformly prevents GVHD, recapitulating the predisposition to tolerance observed after fetal allotransplantation. These findings demonstrate fetal resistance to GVHD following hematopoietic cell transplantation and elucidate Tregs as important contributors.

BACKGROUND:Maternal transplacental administration of sildenafil is being considered for a variety of fetal conditions. Clinical translation also requires evaluation of fetal safety in a higher species, such as the fetal lamb. Experiments with the pregnant ewe are curtailed by minimal transplacental transfer as well as limited access to the fetus. The EXTra-uterine Environment for Neonatal Development (EXTEND) model renders the isolated fetal lamb readily accessible and allows for direct fetal administration of sildenafil. METHODS:Five fetal lambs were placed on extracorporeal support in the EXTEND device and received continuous intravenous (IV) sildenafil (0.3-0.5-0.7 mg/kg/24hr) for a duration of one to seven days. Plasma sildenafil concentrations were sampled at regular intervals to establish the pharmacokinetic profile using population pharmacokinetic modeling. Serial Doppler ultrasound examination, continuous non-invasive hemodynamic monitoring and blood gas analysis were done to evaluate the pharmacodynamic effects and fetal response. FINDINGS/RESULTS:The target concentration range (47-500 ng/mL) was attained with all doses. Sildenafil induced an immediate and temporary reduction of pulmonary vascular resistance, mean arterial pressure and circuit flow, without change in fetal lactate levels and acid-base status. The duration of the systemic effects increased with the dose. INTERPRETATION/CONCLUSIONS:Immediate temporary pulmonary vascular and systemic hemodynamic changes induced by sildenafil were biochemically well tolerated by fetal lambs on extracorporeal support, with the 0.5 mg/kg/24 h dose balancing rapid attainment of target concentrations with short-lived systemic effects. RESEARCH IN CONTEXT/BACKGROUND:None. SEARCH STRATEGY BEFORE UNDERTAKING THE STUDY/UNASSIGNED:A literature review was conducted searching online databases (Medline, Embase and Cochrane), using search terms: fetal OR prenatal OR antenatal AND sildenafil, without time-limit and excluding human studies. Where relevant, investigators were contacted in order to avoid duplication of work. EVIDENCE BEFORE THIS STUDY/UNASSIGNED:Prenatal therapy with sildenafil, a phosphodiesterase-5 inhibitor with vasodilatory and anti-remodeling effects on vascular smooth muscle cells, has been considered for a variety of fetal conditions. One multicenter clinical trial investigating the benefit of sildenafil in severe intrauterine growth restriction (the STRIDER-trial) was halted early due to excess mortality in the sildenafil-exposed arm at one treatment site. Such findings demonstrate the importance of extensive preclinical safety assessment in relevant animal models. Transplacentally administered sildenafil leads to decreased pulmonary arterial muscularization, preventing or reducing the occurrence of pulmonary hypertension in rat and rabbit fetuses with diaphragmatic hernia (DH). Validation of these results in a higher and relevant animal model, e.g. fetal lambs, is the next step to advance clinical translation. We recently demonstrated that, in contrast to humans, transplacental transfer of sildenafil in sheep is minimal, precluding the in vivo study of fetal effects at target concentrations using the conventional pregnant ewe model. ADDED VALUE OF THIS STUDY/UNASSIGNED:We therefore used the extracorporeal support model for fetal lambs, referred to as the EXTra-uterine Environment for Neonatal Development (EXTEND) system, bypassing placental and maternal metabolism, to investigate at what dose the target concentrations are reached, and what the fetal hemodynamic impact and response are. Fetal hemodynamic and metabolic tolerance to sildenafil are a crucial missing element on the road to clinical translation. This is therefore the first study investigating the pharmacokinetics, hemodynamic and biochemical effects of clinical-range concentrations of sildenafil in fetal lambs, free from placental and maternal interference. IMPLICATIONS OF ALL THE AVAILABLE EVIDENCE/UNASSIGNED:We demonstrated self-limiting pulmonary vasodilation, a decrease of both systemic arterial pressures and circuit flows, induced by clinical range concentrations of sildenafil, without the development of fetal acidosis. This paves the way for further investigation of prenatal sildenafil in fetal lambs on extracorporeal support. A dose of 0.5 mg/kg/24 h offered the best trade-off between rapid achievement of target concentrations and shortest duration of systemic effects. This is also the first study using the EXTEND as a model for pharmacotherapy during pregnancy.

BACKGROUND:Minimally invasive fetal surgery, or fetoscopy, is an alternative to open fetal surgery to repair common birth defects like myelomeningocele. Although this hysterotomy-sparing approach reduces maternal morbidity, the effects of in utero insufflation on the fetus are poorly understood. Our purpose was to determine the optimal fetal insufflation conditions. METHODS:without amniotic fluid (skin and cord exposed) (n=3). RESULTS:with an exposed umbilical cord led to reduced umbilical blood flow. CONCLUSIONS:with an amniotic fluid covered umbilical cord is well tolerated by the fetus without significant changes in hemodynamics or cerebral perfusion parameters. TYPE OF STUDY/METHODS:Basic science LEVEL OF EVIDENCE: N/A.

OBJECTIVES/OBJECTIVE:Contrast-enhanced ultrasound (CEUS) can provide quantitative perfusion metrics and may be useful to detect cerebral pathology in neonates and premature infants, particularly in extrauterine environments. The effect of hemodynamics on cerebral perfusion metrics is unknown, which limits the clinical application of this technology. We aimed to determine associations between systemic hemodynamics and concurrently measured brain perfusion parameters in an animal model of extrauterine support. METHODS:Nine fetal lambs were transferred to an extrauterine support device. Lumason® ultrasound contrast (0.1-0.3 ml) was administered via the umbilical vein and 90-second cine clips were obtained. Time-intensity-curves (TICs) were generated and time-dependent and area-under-curve (AUC) parameters were derived. Associations between brain perfusion metrics and hemodynamics including heart rate (HR) and mean arterial pressure (MAP) were evaluated by multilevel linear mixed-effects models. RESULTS:Eighty-six ultrasound examinations were performed and 72 examinations were quantifiable. Time-dependent measurements were independent of all hemodynamic parameters (all p ≥.05). Oxygen delivery and mean blood flow were correlated with AUC measurements (all p ≤.01). Physiologic HR and MAP were not correlated with any measurements (all p ≥.05). CONCLUSION/CONCLUSIONS:Detected aberrations in time-dependent CEUS measurements are not correlated with hemodynamic parameters and are thought to reflect the changes in cerebral blood flow, thus providing a promising tool for evaluation of brain perfusion. CEUS brain perfusion parameters are not correlated with physiologic HR and MAP, but AUC-dependent measurements are correlated with oxygen delivery and blood flow, suggesting that CEUS offers additional value over standard monitoring. Overall, these findings enhance the applicability of this technology.

BACKGROUND:Perioperative recovery often involves the need for supplemental nutrition (either enteral or parenteral). Furthermore, long-term effects of early satiety, dysphagia, sustained weight loss, and difficulty in maintaining a healthy weight, dumping syndrome, and intestinal overgrowth are not unusual. Although the alternative of untreated cancer is clearly unacceptable, these lifestyle consequences are not benign. METHODS:A retrospective review of patients who had undergone laparoscopic total and proximal gastrectomy for gastric adenocarcinoma was conducted. Patient demographic data, pathologic parameters, and short-term and long-term clinical data were compared between total gastrectomy and proximal gastrectomy cohorts. RESULTS: = .009) were also higher in the LTG group. There was no significant difference in terms of mean estimated blood loss or blood transfusion rates, overall complications, or anastomotic stricture requiring endoscopic dilation between the patients who underwent LTG and those who underwent LPG. CONCLUSION/CONCLUSIONS:In early stage tumors (T1b or T2), proximal gastrectomy (PG) should be considered to mitigate diminished quality of life. PG with esophagogastrostomy, which can easily be performed minimally invasively, can be more tolerable for the patient, with no anatomic basis for dumping syndrome or small intestinal bacterial overgrowth (SIBO), and a greater reservoir for more normal meal habits when compared to total gastrectomy (TG) with Roux-en-Y reconstruction.

Gene therapy has traditionally involved the delivery of exogenous genetic material to a cell-most commonly to replace defective genes causing monogenic disorders. This allows cells to produce proteins that are otherwise absent in sufficient quantities, ideally for a therapeutic purpose. Since its inception over 40 years ago, the field of gene therapy has significantly expanded and now includes targeted gene editing strategies, including, but not limited to, clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9), transcription activator-like effector nucleases (TALENs), and zinc-finger nucleases (ZFNs).