Enteric neural stem/progenitor cells (ENSCs) offer an innovative approach to treating Hirschsprung disease (HSCR) and other enteric neuropathies. However, postnatal-derived human ENSCs have not been ...thoroughly characterized and their behavior in the embryonic and postnatal intestinal environment is unknown.
ENSCs were isolated from the intestines of 25 patients undergoing bowel resection, including 7 children with HSCR. Neuronal differentiation and proliferation of ENSCs from submucosal and myenteric plexuses from patients with and without HSCR were characterized. ENSC migration and differentiation were studied following transplantation into embryonic chick neural crest, embryonic chick hindgut, and postnatal mouse aganglionic colon.
The proliferative and neurogenic potential of ENSCs from HSCR intestine is equivalent to that of non-HSCR controls. Similarly, no difference was observed between myenteric- and submucosal-derived ENSCs. Postnatal ENSCs transplanted to embryonic neural crest pathways and to aneural hindgut migrate normally and differentiate into appropriate neural crest-derived cell types. ENSCs in postnatal mouse aganglionic colon differentiate into neurons and glia both ex vivo and in vivo.
ENSCs isolated from the postnatal intestine of patients with and without HSCR can behave like embryonic neural crest-derived cells. These results support the feasibility of cell-based therapy for future treatment of neurointestinal disease.
OBJECTIVE:The aim of this study was to examine the challenges confronting surgeons performing basic science research in todayʼs academic surgery environment.
SUMMARY OF BACKGROUND DATA:Multiple ...studies have identified challenges confronting surgeon-scientists and impacting their ability to be successful. Although these threats have been known for decades, the downward trend in the number of successful surgeon-scientists continues. Clinical demands, funding challenges, and other factors play important roles, but a rigorous analysis of academic surgeons and their experiences regarding these issues has not previously been performed.
METHODS:An online survey was distributed to 2504 members of the Association for Academic Surgery and Society of University Surgeons to determine factors impacting success. Survey results were subjected to statistical analyses. We also reviewed publicly available data regarding funding from the National Institutes of Health (NIH).
RESULTS:NIH data revealed a 27% decline in the proportion of NIH funding to surgical departments relative to total NIH funding from 2007 to 2014. A total of 1033 (41%) members responded to our survey, making this the largest survey of academic surgeons to date. Surgeons most often cited the following factors as major impediments to pursuing basic investigationpressure to be clinically productive, excessive administrative responsibilities, difficulty obtaining extramural funding, and desire for work-life balance. Surprisingly, a majority (68%) did not believe surgeons can be successful basic scientists in todayʼs environment, including departmental leadership.
CONCLUSIONS:We have identified important barriers that confront academic surgeons pursuing basic research and a perception that success in basic science may no longer be achievable. These barriers need to be addressed to ensure the continued development of future surgeon-scientists.
The enteric nervous system (ENS) develops from neural crest cells that migrate along the intestine, differentiate into neurons and glia, and pattern into two plexuses within the gut wall. Inductive ...interactions between epithelium and mesenchyme regulate gut development, but the influence of these interactions on ENS development is unknown. Epithelial-mesenchymal recombinations were constructed using avian hindgut mesenchyme and non-intestinal epithelium from the bursa of Fabricius. These recombinations led to abnormally large and ectopically positioned ganglia. We hypothesized that sonic hedgehog (Shh), a secreted intestinal epithelial protein not expressed in the bursa, mediates this effect. Inhibition of Shh signaling, by addition of cyclopamine or a function-blocking antibody, resulted in large, ectopic ganglia adjacent to the epithelium. Shh overexpression, achieved in ovo using Shh-encoding retrovirus and in organ culture using recombinant protein, led to intestinal aganglionosis. Shh strongly induced the expression of versican and collagen type IX, whereas cyclopamine reduced expression of these chondroitin sulfate proteoglycans that are known to be inhibitory to neural crest cell migration. Shh also inhibited enteric neural crest-derived cell (ENCC) proliferation, promoted neuronal differentiation, and reduced expression of Gdnf, a key regulator of ENS formation. Ptc1 and Ptc2 were not expressed by ENCCs, and migration of isolated ENCCs was not inhibited by Shh protein. These results suggest that epithelial-derived Shh acts indirectly on the developing ENS by regulating the composition of the intestinal microenvironment.
Avian influenza virus subtype H5N1 is a potential pandemic threat with human-adapted strains resistant to antiviral drugs. Although virtual screening (VS) against a crystal or relaxed receptor ...structure is an established method to identify potential inhibitors, the more dynamic changes within binding sites are neglected. To accommodate full receptor flexibility, we use AutoDock4 to screen the NCI diversity set against representative receptor ensembles extracted from explicitly solvated molecular dynamics simulations of the neuraminidase system. The top hits are redocked to the entire nonredundant receptor ensemble and rescored using the relaxed complex scheme (RCS). Of the 27 top hits reported, half ranked very poorly if only crystal structures are used. These compounds target the catalytic cavity as well as the newly identified 150- and 430-cavities, which exhibit dynamic properties in electrostatic surface and geometric shape. This ensemble-based VS and RCS approach may offer improvement over existing strategies for structure-based drug discovery.
Abstract Cell therapy offers an innovative approach for treating enteric neuropathies. Postnatal gut-derived enteric neural stem/progenitor cells (ENSCs) represent a potential autologous source, but ...have a limited capacity for proliferation and neuronal differentiation. Since serotonin (5-HT) promotes enteric neuronal growth during embryonic development, we hypothesized that serotonin receptor agonism would augment growth of neurons from transplanted ENSCs. Postnatal ENSCs were isolated from 2 to 4 week-old mouse colon and cultured with 5-HT4 receptor agonist (RS67506)-loaded liposomal nanoparticles. ENSCs were co-cultured with mouse colon explants in the presence of RS67506-loaded (n = 3) or empty nanoparticles (n = 3). ENSCs were also transplanted into mouse rectum in vivo with RS67506-loaded (n = 8) or blank nanoparticles (n = 4) confined in a thermosensitive hydrogel, Pluronic F-127. Neuronal density and proliferation were analyzed immunohistochemically. Cultured ENSCs gave rise to significantly more neurons in the presence of RS67506-loaded nanoparticles. Similarly, colon explants had significantly increased neuronal density when RS67506-loaded nanoparticles were present. Finally, following in vivo cell delivery, co-transplantation of ENSCs with 5-HT4 receptor agonist-loaded nanoparticles led to significantly increased neuronal density and proliferation. We conclude that optimization of postnatal ENSCs can support their use in cell-based therapies for neurointestinal diseases.
Ex-utero intrapartum treatment has been established as an option for fetal and perinatal surgeons to deliver patients with sacrococcygeal teratomas (SCTs) which are causing significant fetal distress ...and possible in-utero fetal demise. However, ex-utero intrapartum treatment procedures carry significant maternal risk and morbidity. Herein, we report an alternative technique of Cesarean section to immediate resection (CSIR) for managing high-risk SCTs.
A retrospective institutional review board–approved review was performed on all SCTs evaluated at our fetal center from May 2014 to September 2020. Demographics; prenatal imaging characteristics; prenatal interventions; and postnatal surgery data including operative time, estimated blood loss, pathology, and outcomes were collected. Outcomes of interest included surveillance serum alpha-fetoprotein levels, imaging surveillance, developmental milestones, and the presence or absence of constipation or fecal incontinence.
A total of 20 patients with prenatal diagnosis of SCT were evaluated. Mothers who transferred their care to another institution after diagnosis were excluded from this study. Twelve neonates underwent standard postnatal resection. Three neonates underwent emergent CSIR for high output cardiac failure, fetal anemia, or concerns for in-utero hemorrhagic rupture. The median (interquartile range) operative time was 231.5 (113) minutes for the standard operative group versus 156 min in the CSIR group. We present three patients who underwent immediate resection after emergent Cesarean section. We report 100% survival for the three consecutive cases.
CSIR is a safe and feasible approach for managing appropriately selected high-risk SCTs with signs of hydrops, fetal distress, or fetal anemia. Despite patient prematurity, we demonstrated 100% survival of three consecutive cases. We suggest that CSIR be considered an option in the management algorithm for high-risk SCTs.
The surgeon–scientist brings a unique perspective to surgical research. The Association of Academic Surgeons and Society of University Surgeons foster the development of surgeon–scientists through ...foundation awards to residents and junior faculty. We sought to evaluate the academic success of surgeons who received an Association for Academic Surgery/Society of University Surgeons award.
Information was collected for individuals who received a resident or junior faculty research award from the Association for Academic Surgery or Society of University Surgeons. Google Scholar, Scopus, and the National Institutes of Health Research Portfolio Online Reporting Tools: Expenditures and Results were used to assess scholarly achievements.
Eighty-two resident awardees were included, 31 (38%) of whom were female. Thirteen (24%) are now professors, 12 (22%) are division chiefs, and 4 (7%) are department chairs. Resident awardees have a median of 886 citations (interquartile range 237–2,111) and an H-index of 14 (interquartile range 7–23). Seven (13%) went on to receive K08/K23 awards, and 7 (13%) received R01s, with a total of about $200 million in National Institutes of Health funding (79-fold return on investment). Thirty-four junior faculty awardees were included, 10 (29%) of whom were female. Thirteen (38%) are now professors, 12 (35%) are division chiefs, and 7 (21%) are department chairs. Faculty awardees have a median of 2,617 citations (interquartile range 1,343–7,857) and an H-index of 25 (interquartile range 18–49). Four (12%) received K08 or K23 awards, and 10 (29%) received R01s, with about $139 million in National Institutes of Health funding (98-fold return on investment).
Association for Academic Surgery/Society of University Surgeons research awardees experience high degrees of success in academic surgery. Most resident awardees pursue fellowship training and remain in academic surgery. A high percentage of both faculty and resident awardees hold leadership positions and successfully achieve National Institutes of Health funding.
Preparing a grant proposal is no small feat, especially for research (R-series) grants from the National Institutes of Health. The National Institutes of Health is the largest public funder of ...biomedical research in the world, and as such, procuring a research grant from the National Institutes of Health is one of the ultimate benchmarks of success for a surgeon–scientist. Most investigators are familiar with the page limits for most R-series grants (12 pages for an R01 and 6 pages for an R21), with the addition of a single page allotted for the specific aims. Interestingly, despite the usual focus on the aforementioned research section, the rest of the application can routinely consist of an additional 100 to 150 pages, which means that pages allotted for the specific aims and research strategy represent only 10% of the complete application package. For busy surgeons, it is this abundance of ancillary documentation that can make preparing a research grant particularly onerous. Fortunately, for some, support exists within the department to help prepare much of this documentation by drawing from previous sources, templates, and boilerplate language that has been developed. Although these resources can significantly reduce the burden on individual investigators, there is a danger of leaning on generalized templates that can dilute the message of the overall grant proposal and introduce extraneous or incorrect information that can ultimately impact the cohesiveness and ultimately the competitiveness of the grant. The focus of this article is to educate surgeon–scientists regarding the purpose and importance of the ancillary information required for National Institutes of Health research grants and how to make the most of institutional resources while tailoring these materials to create a cohesive, competitive grant application.
The emergence and continuing global spread of the highly virulent avian influenza H5N1 has raised concerns of a possible human pandemic. Several approved anti-influenza drugs effectively target the ...neuraminidase (NA), a surface glycoprotein that cleaves terminal sialic acid residues and facilitates the release of viral progeny from infected cells. The first crystal structures of group-1 NAs revealed that although the binding pose of oseltamivir was similar to that seen in previous crystallographic complexes, the 150-loop adopted a distinct conformation, opening a new cavity adjacent to the active site. Here we show that the 150-loop is able to open into significantly wider conformations than seen in the crystal structures, through explicitly solvated MD simulations of the apo and oseltamivir-bound forms of tetrameric N1. We find that motion in the 150-loop is coupled to motion in the neighboring 430-loop, which expands the active site cavity even further. Furthermore, in simulations of the oseltamivir-bound system, the 150-loop approaches the closed conformation, suggesting that the loop switching motion may be more rapid than previously observed.
Abstract Purpose Recent evidence suggests that patients with Hirschsprung disease (HD) have abnormal neurotransmitter expression in the ganglionated proximal colon. These alterations may cause ...persistent bowel dysfunction even after pullthrough surgery. We sought to quantify the proportion of nitrergic neurons in the ganglionic colon of HD patients and relate these findings to functional outcome. Methods The proximal resection margin from 17 patients with colonic HD who underwent a pullthrough procedure and colorectal tissue from 4 age-matched controls were immunohistochemically examined to quantify the proportion of nitrergic neurons. The incidence of constipation, incontinence, and enterocolitis in HD patients was assessed retrospectively and correlated with the proportion of nitric oxide synthase (NOS) expressing neurons. Neuronal subtypes in the ganglionic colon of the Edrnb −/− mouse model of HD were also studied. Results Mice with HD had a significantly higher proportion of NOS + neurons in ganglionic colon than normal littermates (32.0 ± 5.6% vs. 19.8 ± 1.2%, p < 0.01). Patients with HD also had significantly more NOS + neurons than controls (18.4 ± 4.6% vs. 13.1 ± 1.9%, p < 0.01). Patients who experienced constipation or enterocolitis postoperatively tended toward a higher proportion of NOS + neurons (21.4 ± 3.9% vs. 17.1 ± 4.1%, p = 0.06). Furthermore, patients with a proportion of NOS + neurons above the median of all HD patients (18.3%) were significantly more likely to have constipation than those below the median (75% vs. 14%, p < 0.05). Conclusion An overabundance of nitrergic neurons in the proximal resection margin is associated with HD and may predict bowel dysfunction following pullthrough surgery. Level Of Evidence Diagnostic, Level III
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