Long noncoding RNA GATA2-AS1 augments endothelial hypoxia inducible factor 1-α induction and regulates hypoxic signaling.

Vascular endothelial cells form the inner cellular lining of blood vessels and have myriad physiologic functions including angiogenesis and response to hypoxia. We recently identified a set of endothelial cell (EC)-enriched long noncoding RNAs (lncRNAs) in differentiated human primary cell types and described the role of the STEEL lncRNA in angiogenic patterning. We sought to further understand the role of EC-enriched lncRNAs in physiologic adaptation of the vascular endothelium. In this work, we describe an abundant, cytoplasmic, and EC-enriched lncRNA, GATA2-AS1, that is divergently transcribed from the EC-enriched developmental regulator, GATA2. While GATA2-AS1 is largely coexpressed with GATA2 in ECs, GATA2-AS1 and GATA2 appear to be complementary rather than synergistic as they have mostly distinct target genes. Common single nucleotide variants in GATA2-AS1 exons are associated with early-onset coronary artery disease and decreased expression of GATA2-AS1 in endothelial cell lines. In most cells, HIF1-α is central to the transcriptional response to hypoxia, while in ECs, both HIF1-α and HIF2-α are required to coordinate an acute and chronic response, respectively. In this setting, GATA2-AS1 contributes to the "HIF switch" and augments HIF1-α induction in acute hypoxia to regulate HIF1-α/HIF2-α balance. In hypoxia, GATA2-AS1 orchestrates HIF1-α-dependent induction of the glycolytic pathway and HIF1-α-independent maintenance of mitochondrial biogenesis. Similarly, GATA2-AS1 coordinates both metabolism and "tip/stalk" cell signaling to regulate angiogenesis in hypoxic ECs. Furthermore, we find that GATA2-AS1 expression patterns are perturbed in atherosclerotic disease. Together, these results define a role for GATA2-AS1 in the EC-specific response to hypoxia.

Use of wearable point-of-view live streaming technology for virtual physical exam skills training.

We piloted a virtual teaching tool comprised of a chest-mounted smartphone streaming point-of-view footage over videoconferencing software to deliver a physical exam skills session. Compared to medical students taught via third person view through pre-recorded video followed by preceptor-led discussion, a higher proportion of students taught via point-of-view wearable technology reported improved knowledge of demonstrated skills and feeling engaged, comfortable interacting with their tutor, and better able to visualize demonstrated exam maneuvers. This accessible, affordable, and easily replicable innovation can potentially enhance virtual clinical skills teaching and enable novel distant clinical learning opportunities for healthcare professions students and educators.

Nous avons mis à l'essai un outil d'enseignement virtuel, notamment pour les cours de techniques d'examen physique, qui consiste dans le fait de porter un téléphone intelligent fixé sur la poitrine pour diffuser en direct, par le biais d'un logiciel de vidéoconférence, pour réaliser un examen physique plutôt que subjectif. Comparativement aux étudiants en médecine qui pour le cours ont visionné une vidéo préenregistrée prise par caméra objective, suivie d'une discussion dirigée par un précepteur, un plus grand nombre d'étudiants ayant suivi le cours par le biais d'une technologie portable avec par le biais d'un dispositif technologique portable déclarent avoir amélioré leurs connaissances sur les techniques présentées, se sentir engagés et à l'aise pour interagir avec l'enseignant, et avoir été en mesure de bien voir les gestes d'examen montrés. Cette innovation accessible, abordable et facilement reproductible pourrait permettre d'améliorer l'enseignement virtuel des habiletés cliniques et d'offrir de nouvelles possibilités d'enseignement.

Introducing the Escalation Antibiogram: A Simple Tool to Inform Changes in Empiric Antimicrobials in the Nonresponding Patient.

BACKGROUND: Hospital antibiograms guide initial empiric antibiotic treatment selections, but do not directly inform escalation of treatment among nonresponding patients. METHODS: Using gram-negative bacteremia as an exemplar condition, we sought to introduce the concept of an escalation antibiogram. Among episodes of gram-negative bacteremia between 2017 and 2020 from 6 hospitals in the Greater Toronto Area, we generated escalation antibiograms for each of 12 commonly used agents. Among organisms resistant to that antibiotic, we calculated the likelihood of susceptibility to each of the other 11 agents. In subgroup analyses, we examined escalation antibiograms across study years, individual hospitals, community versus hospital onset, and pathogen type. RESULTS: Among 6577 gram-negative bacteremia episodes, the likelihood of coverage was ampicillin 31.8%, cefazolin 62.7%, ceftriaxone 67.1%, piperacillin-tazobactam 72.5%, ceftazidime 74.1%, trimethoprim-sulfamethoxazole 74.4%, ciprofloxacin 77.1%, tobramycin 88.3%, gentamicin 88.8%, ertapenem 91.0%, amikacin 97.5%, and meropenem 98.2%. The escalation antibiograms revealed marked shifts in likelihood of coverage by the remaining 11 agents. For example, among ceftriaxone-resistant isolates, piperacillin-tazobactam susceptibility (21.2%) was significantly lower than trimethoprim-sulfamethoxazole (54.2%, P < .0001), ciprofloxacin (63.0%, P < .0001), ertapenem (73.4%, P < .0001), tobramycin (80.1%, P < .0001), gentamicin (82.8%, P < .0001), meropenem (94.3%, P < .0001), and amikacin (97.1%, P < .0001). Trimethoprim-sulfamethoxazole was the second-ranked agent in the meropenem escalation antibiogram (49.6%) and first in the amikacin escalation antibiogram (86.0%). Escalation antibiograms were consistent across 4 study years and 6 hospitals. CONCLUSIONS: Escalation antibiograms can be generated to inform empiric treatment changes in nonresponding patients. These tools can yield important insights such as avoiding the common maneuver of escalating from ceftriaxone to piperacillin-tazobactam in suspected gram-negative bacteremia.

Virtual breakout rooms: an effective approach to offer guidance to medical students on residency applications.

Peer mentorship on residency applications has been difficult due to recent public health measures, prompting a shift from in-person events to virtual platforms. To address gaps in career exploration, we created a virtual, non-recorded space that allowed medical students and residents to discuss the Canadian Resident Matching Service (CaRMS) process meaningfully and transparently. Attendees reported a greater understanding of the match process and reduced anxiety after the event. This model provides a virtual framework that can be adapted for various mentorship opportunities.

Le mentorat par les pairs offert aux étudiants concernant les demandes de résidence a été difficile à mettre en œuvre en raison des récentes mesures de santé publique, entraînant le transfert des activités en personne vers les plateformes virtuelles. Pour combler les lacunes dans l'exploration des carrières, nous avons créé un espace virtuel, sans enregistrement, qui a permis aux étudiants et aux résidents de discuter du processus du Service canadien de jumelage des résidents (CaRMS) de manière approfondie et transparente. Les participants ont indiqué qu'à la suite de la rencontre, ils comprenaient mieux le processus de jumelage et qu'ils étaient moins anxieux. Ce modèle virtuel peut être adapté et utilisé pour diverses activités de mentorat.

Short bowel mucosal morphology, proliferation and inflammation at first and repeat STEP procedures.

BACKGROUND: Although serial transverse enteroplasty (STEP) improves function of dilated short bowel, a significant proportion of patients require repeat surgery. To address underlying reasons for unsuccessful STEP, we compared small intestinal mucosal characteristics between initial and repeat STEP procedures in children with short bowel syndrome (SBS). METHODS: Fifteen SBS children, who underwent 13 first and 7 repeat STEP procedures with full thickness small bowel samples at median age 1.5 years (IQR 0.7-3.7) were included. The specimens were analyzed histologically for mucosal morphology, inflammation and muscular thickness. Mucosal proliferation and apoptosis was analyzed with MIB1 and Tunel immunohistochemistry. RESULTS: Median small bowel length increased 42% by initial STEP and 13% by repeat STEP (p=0.05), while enteral caloric intake increased from 6% to 36% (p=0.07) during 14 (12-42) months between the procedures. Abnormal mucosal inflammation was frequently observed both at initial (69%) and additional STEP (86%, p=0.52) surgery. Villus height, crypt depth, enterocyte proliferation and apoptosis as well as muscular thickness were comparable at first and repeat STEP (p>0.05 for all). Patients, who required repeat STEP tended to be younger (p=0.057) with less apoptotic crypt cells (p=0.031) at first STEP. Absence of ileocecal valve associated with increased intraepithelial leukocyte count and reduced crypt cell proliferation index (p<0.05 for both). CONCLUSIONS: No adaptive mucosal hyperplasia or muscular alterations occurred between first and repeat STEP. Persistent inflammation and lacking mucosal growth may contribute to continuing bowel dysfunction in SBS children, who require repeat STEP procedure, especially after removal of the ileocecal valve. LEVEL OF EVIDENCE: Level IV, retrospective study.

Characterization of Patients with Ibuprofen Hypersensitivity.

BACKGROUND: Ibuprofen is the most frequently used over-the-counter nonsteroidal anti-inflammatory drug (NSAID) in North America. While it has been commonly implicated in drug-induced hypersensitivity reactions, there is limited literature specifically on ibuprofen hypersensitivity. OBJECTIVES: To characterize the demographics and clinical course of hypersensitivity reactions in a cohort of patients with ibuprofen allergy. METHODS: A retrospective chart review of patients diagnosed with ibuprofen allergy was conducted between 2008 and 2016 in an allergy clinic at a tertiary care academic institution. Demographics and clinical information were obtained, and severity of reactions was assessed by a standardized grading system. RESULTS: A total of 41 patients were included of whom 27 were female. The mean age at first reaction to ibuprofen was 33 ± 13.9 years. The medi an time from the first reaction to the time of diagnosis was 1 year (0-3). The median time from ibuprofen exposure to the onset of symptoms was 30 min (16-101). The median duration of symptoms was 180 min (60-1,440). Urticaria and angioedema were seen in 90% of patients. The reactions were either mild (46%) or moderate (51%) in severity, but 1 patient had severe anaphylaxis. Cross-reactivity to other NSAIDs or acetaminophen was seen and presented with mostly mild reactions. CONCLUSION: In our cohort of patients, ibuprofen hypersensitivity affected females more commonly than males, and presented with mainly cutaneous manifestations. Onset of symptoms was rapid (< 60 min). Reactions typically ranged in severity from mild to moderate although there was a risk of severe anaphylaxis. There was potential cross-reactivity with other NSAIDs or acetaminophen. The results of our study contribute to the understanding of the demographics and clinical course of ibuprofen hypersensitivity reactions.

Critical evaluation of the Hirschsprung-associated enterocolitis (HAEC) score: A multicenter study of 116 children with Hirschsprung disease.

OBJECTIVE: To identify the optimal clinical criteria to diagnose Hirschsprung-associated enterocolitis (HAEC) in children with Hirschsprung disease (HSCR). BACKGROUND: HAEC is the most common life-threatening complication in HSCR patients, yet the diagnostic criteria for HAEC remain unclear. The consensus-based HAEC scoring system was not validated using patient data, thereby making its diagnostic accuracy uncertain. METHODS: From 2009 to 2015, consecutive children with HSCR underwent retrospective evaluation of their medical records, and questionnaire-directed parent interviews to identify treatment of suspected HAEC episodes and the 16 clinical criteria in the HAEC score. Logistic regression modeling was employed to identify criteria predicting suspected HAEC episodes. RESULTS: One hundred sixteen HSCR patients met inclusion criteria, 43 patients (37.1%) were treated for at least one suspected HAEC episode. An HAEC score of 4 maximized the sum of sensitivity (83.7%) and specificity (98.6%) while the previously established cut-off score of 10 showed lower sensitivity (41.9%) with perfect specificity. Multivariable analysis identified four criteria utilized to create a new HAEC Risk score with performance characteristics similar to the HAEC score cutoff of 4. CONCLUSION: When using the HAEC score, a cutoff of 4 should be used rather than 10, which under-diagnosed patients with HAEC. Alternatively, the new HAEC Risk score could be employed. LEVEL OF EVIDENCE: Diagnostic Study, Level 3.

Reduced paraspinous muscle area is associated with post-colectomy complications in children with ulcerative colitis.

BACKGROUND AND OBJECTIVES: Sarcopenia, defined as reduced muscle mass, is typically assessed by CT scans, which are infrequently performed in children. Using MRI to measure sarcopenia, we determined the association with postoperative complications after colectomy for ulcerative colitis (UC). METHODS: Clinical and preoperative MRI data for 13-18-year-old UC patients who underwent colectomy were retrospectively reviewed. Bilateral paraspinous muscle area (PSMA) and psoas muscle area (PMA) at L3 vertebra were measured and averaged. Composite complications were infection, wound dehiscence, postoperative leak/abscess, prolonged ileus, pulmonary embolism, venous thromboembolism, or readmission. RESULTS: Twenty-nine patients with average age 15.9±1.36years and weight 61.5±19.8kg had a preoperative MRI. The 18/29(62%) with complications had significantly reduced PSMA (4.71±1.44 vs 5.64±1.38cm2, p=0.04) and PMA (7.16±2.60 vs 8.93±2.44, p=0.04). When stratified and compared to highest PSMA, patients with lowest PSMA had increased complication rates (88% vs 29%, p=0.04). There were no differences in age, BMI, albumin, CRP, ESR, or preoperative steroid or anti-TNFα use. Odds of complication in the lowest tertile were 25.0-fold higher than the highest tertile (p=0.04, 95% CI=1.2-520.73). CONCLUSION: This is the first study to show low PSMA on MRI is associated with complications and increased hospital stay after colectomy in children with UC. LEVELS OF EVIDENCE: Level III retrospective comparative study.

Interdependency of EGF and GLP-2 Signaling in Attenuating Mucosal Atrophy in a Mouse Model of Parenteral Nutrition.

BACKGROUND & AIMS: Total parenteral nutrition (TPN), a crucial treatment for patients who cannot receive enteral nutrition, is associated with mucosal atrophy, barrier dysfunction, and infectious complications. Glucagon-like peptide-2 (GLP-2) and epidermal growth factor (EGF) improve intestinal epithelial cell (IEC) responses and attenuate mucosal atrophy in several TPN models. However, it remains unclear whether these 2 factors use distinct or overlapping signaling pathways to improve IEC responses. We investigated the interaction of GLP-2 and EGF signaling in a mouse TPN model and in patients deprived of enteral nutrition. METHODS: Adult C57BL/6J, IEC-Egfrknock out (KO) and IEC-pik3r1KO mice receiving TPN or enteral nutrition were treated with EGF or GLP-2 alone or in combination with reciprocal receptor inhibitors, GLP-2(3-33) or gefitinib. Jejunum was collected and mucosal atrophy and IEC responses were assessed by histologic, gene, and protein expression analyses. In patients undergoing planned looped ileostomies, fed and unfed ileum was analyzed. RESULTS: Enteral nutrient deprivation reduced endogenous EGF and GLP-2 signaling in mice and human beings. In the mouse TPN model, exogenous EGF or GLP-2 attenuated mucosal atrophy and restored IEC proliferation. The beneficial effects of EGF and GLP-2 were decreased upon Gefitinib treatment and in TPN-treated IEC-EgfrKO mice, showing epidermal growth factor-receptor dependency for these IEC responses. By contrast, in TPN-treated IEC-pi3kr1KO mice, the beneficial actions of EGF were lost, although GLP-2 still attenuated mucosal atrophy. CONCLUSIONS: Upon enteral nutrient deprivation, exogenous GLP-2 and EGF show strong interdependency for improving IEC responses. Understanding the differential requirements for phosphatidylinositol 3-kinase/phosphoAKT (Ser473) signaling may help improve future therapies to prevent mucosal atrophy.

Antegrade continence enemas improve quality of life in patients with medically-refractory encopresis.

PURPOSE: Fecal incontinence is a socially debilitating problem for many children. We hypothesized that in selected patients with medically-refractory encopresis, placement of an appendicostomy or cecostomy tube for administration of antegrade continence enemas (ACE) would improve quality of life (QOL). METHODS: We reviewed all patients with encopresis who underwent appendicostomy or cecostomy placement from 2003 to 2014 at our institution. We contacted subjects' parents by phone and administered 3 surveys: a survey reflecting current stooling habits, a disease-specific QOL survey, and the PedsQL™ QOL survey. QOL surveys were completed twice by parents, once reflecting pre-operative QOL, then again reflecting current QOL. Pre-procedure and post-procedure scores were compared by paired t-test. RESULTS: Ten patients underwent appendicostomy/cecostomy for encopresis. Eight completed phone surveys. All procedures were performed laparoscopically. All patients experienced fecal soiling pre-operatively, whereas 5/8 surveyed patients (63%) noted complete resolution of soiling post-procedure (p<0.01). General and disease-specific QOL improved from pre-procedure to post-procedure in the following domains: social habits, physical activity, ability to spend the night elsewhere, feeling, and overall QOL (p<0.05). PedsQL™ scores improved significantly in physical functioning, social functioning, and overall functioning (p<0.05). CONCLUSIONS: Antegrade continence enemas significantly improve quality of life in patients with medically-refractory encopresis, likely related to resolution of soiling. LEVEL OF EVIDENCE: 4.

Redo pullthrough for Hirschsprung disease.

Pullthrough procedures for Hirschsprung diseases typically have favorable results. However, some children experience long-term postoperative complications comprising stooling disorders, such as intermittent enterocolitis, severe stool retention, intestinal obstruction, as well as incontinence. Reoperative Hirschsprung Disease surgery is complex. This begins with the workup after the initial presentation following primary pullthrough, continues with the definitive surgical correction with redo pullthrough, and ends with long-term follow-up of individuals. The decision tree can be varied with each patient. The operating pediatric surgeon must be able to utilize different operations and treatment options available. While lesser procedures may provide relief in a select population, those with residual aganglionosis or transition zone pathology or mechanical problems will likely require a redo pullthrough. Thus, the diagnostic workup, treatment plan, and definitive surgical care should be coordinated, and executed by an experienced, specialized team at a pediatric referral center.

Ethanol Lock Therapy for the Treatment of Intravenous Catheter Infections That Have Failed Standard Treatment.

This study used ethanol lock therapy (ELT) to treat intravenous catheter infections that had failed standard intravenous antimicrobial treatment. Of 15 patients enrolled, 13 were successfully treated with ELT. Twenty-one organisms were identified: 12 bacteria, 9 fungi. Eight of the 9 fungi were eradicated, and no patient became hemodynamically unstable on treatment.

Magnetic resonance imaging (MRI)-assisted laparoscopic anorectoplasty for imperforate anus: a single center experience.

PURPOSE: Surgical procedures for high imperforate anus have ranged from the posterior sagittal anorectoplasty (PSARP) to laparoscopic-assisted anorectoplasty (LAARP). PSARP bisects the sphincter muscle complex, introducing muscle injury and scarring. LAARP uses a straight trocar to traverse an often non-linear sphincter muscle complex. MRI-assisted LAARP (MRI-LAARP) guides the neorectum precisely through the middle of the entire sphincter complex along its trajectory. We present our experience utilizing MRI intraoperatively during LAARP. METHODS/PROCEDURE: Ten children underwent MRI-LAARP procedures. Intraoperative MRI was performed to delineate the sphincter complex, and to guide the advancement of an MRI-compatible needle through the center of the complex from skin to the peritoneal cavity. The remainder of the procedure was completed using the standard LAARP technique. RESULTS: All had successful MRI needle placement through the sphincter complex. Nine patients had successful laparoscopic pull-through procedures; one was converted to open due to severe intraperitoneal adhesions. Postoperative stay averaged 5.4 ± 4.4 days. Out of the ten patients, one child had mild dehiscence of the anal anastomosis requiring revision 11 days postoperatively. CONCLUSION: The theoretical advantage of the MRI-LAARP is placing the neorectum through the entire sphincter complex without transecting the muscle. Follow-up of these patients shows good short-term results; however, long-term follow-up will be needed to best assess sphincter and bowel function.

Ultrasound-guided intrasphincteric botulinum toxin injection relieves obstructive defecation due to Hirschsprung's disease and internal anal sphincter achalasia.

PURPOSE: Chronic obstructive defecation can occur in patients with Hirschsprung Disease (HD) and internal anal sphincter (IAS) achalasia. Injection of Botulinum Toxin (BoTox) into the IAS can temporarily relieve obstructive defecation, but can be challenging when performed by tactile sense alone. We compared results of BoTox injections with and without ultrasound (US) guidance. METHODS: We retrospectively reviewed BoTox injections into the IAS for obstructive defecation over 5years. Analyzed outcomes included short-term improvement, defined as resolution of enterocolitis, new ability to spontaneously defecate, and/or normalization of bowel movement frequency 2weeks post-operatively, as well as requirement of more definitive surgical therapy (myotomy/myomectomy, colectomy, colostomy, cecostomy/appendicostomy, and/or sacral nerve stimulator implantation). Outcomes were compared using t-test and Fisher's Exact test, with significance defined as p<0.05. RESULTS: Twelve patients who underwent BoTox injection were included, including 5 patients who underwent injections both with and without ultrasound. Ten underwent an ultrasound-guided injection (13 injection procedures), 5 of whom had HD. Seven underwent an injection without ultrasound guidance (17 injection procedures), 5 of whom had HD. Procedures performed with US resulted in greater short-term improvement (76% versus 65% without ultrasound) and less requirement of a definitive procedure for obstructive defecation (p<0.05). CONCLUSIONS: US-guided BoTox injection is safe and effective for obstructive defecation, and may decrease the need for a definitive operation. LEVEL OF EVIDENCE: III.

Outcomes from a 12-Week, Open-Label, Multicenter Clinical Trial of Teduglutide in Pediatric Short Bowel Syndrome.

OBJECTIVE: To determine safety and pharmacodynamics/efficacy of teduglutide in children with intestinal failure associated with short bowel syndrome (SBS-IF). STUDY DESIGN: This 12-week, open-label study enrolled patients aged 1-17 years with SBS-IF who required parenteral nutrition (PN) and showed minimal or no advance in enteral nutrition (EN) feeds. Patients enrolled sequentially into 3 teduglutide cohorts (0.0125 mg/kg/d [n = 8], 0.025 mg/kg/d [n = 14], 0.05 mg/kg/d [n = 15]) or received standard of care (SOC, n = 5). Descriptive summary statistics were used. RESULTS: All patients experienced ≥1 treatment-emergent adverse event; most were mild or moderate. No serious teduglutide-related treatment-emergent adverse events occurred. Between baseline and week 12, prescribed PN volume and calories (kcal/kg/d) changed by a median of -41% and -45%, respectively, with 0.025 mg/kg/d teduglutide and by -25% and -52% with 0.05 mg/kg/d teduglutide. In contrast, PN volume and calories changed by 0% and -6%, respectively, with 0.0125 mg/kg/d teduglutide and by 0% and -1% with SOC. Per patient diary data, EN volume increased by a median of 22%, 32%, and 40% in the 0.0125, 0.025, and 0.05 mg/kg/d cohorts, respectively, and by 11% with SOC. Four patients achieved independence from PN, 3 in the 0.05 mg/kg/d cohort and 1 in the 0.025 mg/kg/d cohort. Study limitations included its short-term, open-label design, and small sample size. CONCLUSIONS: Teduglutide was well tolerated in pediatric patients with SBS-IF. Teduglutide 0.025 or 0.05 mg/kg/d was associated with trends toward reductions in PN requirements and advancements in EN feeding in children with SBS-IF. TRIAL REGISTRATION: ClinicalTrials.gov:NCT01952080; EudraCT: 2013-004588-30.

Taking a STEP back: Assessing the outcomes of multiple STEP procedures.

PURPOSE: Short bowel syndrome (SBS) is a highly morbid condition primarily because of parenteral nutrition (PN)-associated complications. Bowel lengthening via serial transverse enteroplasty (STEP) has become standard of care. While initial STEPs have resulted in weaning from PN, outcomes of repeated STEPs (ReSTEPs) are not well described. We investigated outcomes of initial STEP compared to ReSTEP procedures. METHODS: This retrospective review of STEPs included 17 children and a total of 24 procedures. Demographics, complications, hospital readmission rates, postoperative costs, and PN weaning were analyzed. RESULTS: Neither patient-specific data nor the etiology of SBS was predictive of requiring a ReSTEP. PN weaning was more likely in the year following a first STEP (18% wean rate vs. 0% for ReSTEP, p>.05). No ReSTEP patients reached enteral autonomy. Enteral nutrition (%EN) increases were greater after first STEP compared to ReSTEP (26.0% vs. 4.7%, p=0.03). This trend was true for bowel length as well, where first STEPs resulted in a 51% increase in bowel length compared to a 20% increase after in ReSTEP (p=0.02). CONCLUSIONS: ReSTEPs failed to result in significant PN weaning, with no ReSTEP patients achieving enteral autonomy during follow-up. Given its higher costs, smaller bowel length gains, and limited ability to produce enteral autonomy, surgeons should carefully consider performing ReSTEP procedures. LEVEL OF EVIDENCE: Level III.

Bacterial nutrient foraging in a mouse model of enteral nutrient deprivation: insight into the gut origin of sepsis.

Total parenteral nutrition (TPN) leads to a shift in small intestinal microbiota with a characteristic dominance of Proteobacteria This study examined how metabolomic changes within the small bowel support an altered microbial community in enterally deprived mice. C57BL/6 mice were given TPN or enteral chow. Metabolomic analysis of jejunal contents was performed by liquid chromatography/mass spectrometry (LC/MS). In some experiments, leucine in TPN was partly substituted with [13C]leucine. Additionally, jejunal contents from TPN-dependent and enterally fed mice were gavaged into germ-free mice to reveal whether the TPN phenotype was transferrable. Small bowel contents of TPN mice maintained an amino acid composition similar to that of the TPN solution. Mass spectrometry analysis of small bowel contents of TPN-dependent mice showed increased concentration of 13C compared with fed mice receiving saline enriched with [13C]leucine. [13C]leucine added to the serosal side of Ussing chambers showed rapid permeation across TPN-dependent jejunum, suggesting increased transmucosal passage. Single-cell analysis by fluorescence in situ hybridization (FISH)-NanoSIMS demonstrated uptake of [13C]leucine by TPN-associated bacteria, with preferential uptake by Enterobacteriaceae Gavage of small bowel effluent from TPN mice into germ-free, fed mice resulted in a trend toward the proinflammatory TPN phenotype with loss of epithelial barrier function. TPN dependence leads to increased permeation of TPN-derived nutrients into the small intestinal lumen, where they are predominately utilized by Enterobacteriaceae The altered metabolomic composition of the intestinal lumen during TPN promotes dysbiosis.

Small Bowel Diameter in Short Bowel Syndrome as a Predictive Factor for Achieving Enteral Autonomy.

Children with short bowel syndrome commonly have dilated small bowel. We found that the extent of dilation was associated with bowel length and that both were related to achieving enteral autonomy.