Surgical History and Outcomes in Trisomy 13 and 18: A Thirty-year Review.

BACKGROUND: Patients with Trisomy 13(T13) and 18(T18) have many comorbidities that may require surgical intervention. However, surgical care and outcomes are not well described, making patient selection and family counseling difficult. Here the surgical history and outcomes of T13/ T18 patients are explored. METHODS: A retrospective review of patients with T13 or T18 born between 1990 and 2020 and cared for at a tertiary children's hospital (Riley Hospital for Children, Indianapolis IN) was conducted, excluding those with insufficient records. Primary outcomes of interest were rates of mortality overall and after surgery. Factors that could predict mortality outcomes were also assessed. RESULTS: One-hundred-seventeen patients were included, with 65% T18 and 35% T13. More than half of patients(65%) had four or more comorbidities. Most deaths occurred by three months at median 42.0 days. Variants of classic trisomies (mosaicism, translocation, partial duplication; p = 0.001), higher birth weight(p = 0.002), and higher gestational age(p = 0.01) were associated with lower overall mortality, while cardiac(p = 0.002) disease was associated with higher mortality. Over half(n = 64) underwent surgery at median age 65 days at time of first procedure. The most common surgical procedures were general surgical. Median survival times were longer in surgical rather than nonsurgical patients(p<0.001). Variant trisomy genetics(p = 0.002) was associated with lower mortality after surgery, while general surgical comorbidities(p = 0.02), particularly tracheoesophageal fistula/esophageal atresia(p = 0.02), were associated with increased mortality after surgery. CONCLUSIONS: Trisomy 13 and 18 patients have vast surgical needs. Variant trisomy was associated with lower mortality after surgery while general surgical comorbidities were associated with increased mortality after surgery. Those who survived to undergo surgery survived longer overall. LEVEL OF EVIDENCE: III.

Contrast Challenge Algorithms for Adhesive Small Bowel Obstructions Are Safe in Children: A Multi-Institutional Study.

OBJECTIVE: The purpose of this study was to evaluate the safety of a water-soluble contrast challenge as part of a nonoperative management algorithm in children with an adhesive small bowel obstruction (ASBO). BACKGROUND: Predicting which children will successfully resolve their ASBO with non-operative management at the time of admission remains difficult. Additionally, the safety of a water-soluble contrast challenge for children with ASBO has not been established in the literature. METHODS: A retrospective review was performed of patients who underwent non-operative management for an ASBO and received a contrast challenge across 5 children's hospitals between 2012 and 2020. Safety was assessed by comparing the complication rate associated with a contrast challenge against a pre-specified maximum acceptable level of 5%. Sensitivity, specificity, negative (NPV) and positive (PPV) predictive values of a contrast challenge to identify successful nonoperative management were calculated. RESULTS: Of 82 children who received a contrast challenge, 65% were successfully managed nonoperatively. The most common surgical indications were failure of the contrast challenge or failure to progress after initially passing the contrast challenge. There were no complications related to contrast administration (0%; 95% confidence interval: 0-3.6%, P = 0.03). The contrast challenge was highly reliable in determining which patients would require surgery and which could be successfully managed non-operatively (sensitivity 100%, specificity 86%, NPV 100%, PPV 93%). CONCLUSION: A contrast challenge is safe in children with ASBO and has a high predictive value to assist in clinical decision-making.

Cannulation and decannulation techniques for neonatal ECMO.

In neonates with cardiac and/or respiratory failure, extracorporeal membrane oxygenation (ECMO) continues to be an important method of respiratory and/or cardiovascular support where conventional treatments are failing. ECMO cannulation involves a complex decision-making process to choose the proper ECMO modality and cannulation strategy to match each patient's needs, unique anatomy, and potential complication profile. Initially, all ECMO support involved cannulating both the carotid artery and the internal jugular vein (IJV), known as veno-arterial (VA-ECMO) for cardiac and/or respiratory support. Rarely was cannulation through the chest used. The development of dual-lumen cannulae in the early to mid 1990s addressed the concerns about carotid artery ligation and its impact on neurological outcomes, and allowed single vascular access for veno-venous respiratory support (VV-ECMO). We present a review of cannulation and decannulation techniques for both VA and VV-ECMO in neonates.

Surgical history of Hirschsprung disease.

Harald Hirschsprung presented the first comprehensive and detailed description of clinical outcomes in patients with congenital megacolon. In the century following his discovery, we have seen realization of the etiology, diagnosis, and treatment of Hirschsprung disease. In this article we describe the surgical management of Hirschsprung disease starting with Orvar Swenson, who pioneered the field with the first full thickness transrectal dissection followed by several additional innovative surgeons who have contributed to the modifications that have brought us to the modern surgical management of Hirschsprung Disease.

Modern Biomarkers for Autism Spectrum Disorder: Future Directions.

Autism spectrum disorder is an increasingly prevalent neurodevelopmental disorder in the world today, with an estimated 2% of the population being affected in the USA. A major complicating factor in diagnosing, treating, and understanding autism spectrum disorder is that defining the disorder is solely based on the observation of behavior. Thus, recent research has focused on identifying specific biological abnormalities in autism spectrum disorder that can provide clues to diagnosis and treatment. Biomarkers are an objective way to identify and measure biological abnormalities for diagnostic purposes as well as to measure changes resulting from treatment. This current opinion paper discusses the state of research of various biomarkers currently in development for autism spectrum disorder. The types of biomarkers identified include prenatal history, genetics, neurological including neuroimaging, neurophysiologic, and visual attention, metabolic including abnormalities in mitochondrial, folate, trans-methylation, and trans-sulfuration pathways, immune including autoantibodies and cytokine dysregulation, autonomic nervous system, and nutritional. Many of these biomarkers have promising preliminary evidence for prenatal and post-natal pre-symptomatic risk assessment, confirmation of diagnosis, subtyping, and treatment response. However, most biomarkers have not undergone validation studies and most studies do not investigate biomarkers with clinically relevant comparison groups. Although the field of biomarker research in autism spectrum disorder is promising, it appears that it is currently in the early stages of development.

Transdermal Electrical Neuromodulation for Anxiety and Sleep Problems in High-Functioning Autism Spectrum Disorder: Feasibility and Preliminary Findings.

BACKGROUND: Autism spectrum disorder (ASD) is associated with anxiety and sleep problems. We investigated transdermal electrical neuromodulation (TEN) of the cervical nerves in the neck as a safe, effective, comfortable and non-pharmacological therapy for decreasing anxiety and enhancing sleep quality in ASD. METHODS: In this blinded, sham-controlled study, seven adolescents and young adults with high-functioning ASD underwent five consecutive treatment days, one day of the sham followed by four days of subthreshold TEN for 20 min. Anxiety-provoking cognitive tasks were performed after the sham/TEN. Measures of autonomic nervous system activity, including saliva α-amylase and cortisol, electrodermal activity, and heart rate variability, were collected from six participants. RESULTS: Self-rated and caretaker-rated measures of anxiety were significantly improved with TEN treatment as compared to the sham, with effect sizes ranging from medium to large depending on the rating scale. Sleep scores from caretaker questionnaires also improved, but not significantly. Performance on two of the three anxiety-provoking cognitive tasks and heart rate variability significantly improved with TEN stimulation as compared to the sham. Four of the seven (57%) participants were responders, defined as a ≥ 30% improvement in self-reported anxiety. Salivary α-amylase decreased with more TEN sessions and decreased from the beginning to the end of the session on TEN days for responders. TEN was well-tolerated without significant adverse events. CONCLUSIONS: This study provides preliminary evidence that TEN is well-tolerated in individuals with ASD and can improve anxiety.

Surgical Gastrostomy in Pediatric Patients Undergoing Cardiac Surgery.

BACKGROUND: Practices of performing gastrostomy tubes vary across institutions for patients undergoing cardiac surgery. We aim to elucidate the outcomes of gastrostomy and the duration of feeding assistance in these patients. MATERIALS AND METHODS: Patients undergoing cardiac surgery (CS) at our institution from 2013 to 2017 were retrospectively reviewed using the Society of Thoracic Surgery database. A cohort of non-CS patients undergoing gastrostomy tube (g-tube) placement from 2013 to 2015 was used as control. Technical complications and postoperative feeding intolerance were analyzed. Duration of need for g-tube was also analyzed in patients undergoing CS. RESULTS: The CS group had 144 patients, and the non-CS group had 677 patients. CS patients had a higher incidence of feeding intolerance (18.8% versus 5.6%, P < 0.001) and took longer to attain full feeds (median of 2 versus 1 d, P < 0.001), and this was confirmed on propensity matched analysis. In addition, technical g-tube complications were similar in the two groups. No mortality in CS was attributed to the g-tube. 58% of patients undergoing CS were able to wean from g-tube feeding by 6-12 mo after g-tube placement. CONCLUSIONS: G-tube placement in patients undergoing CS by any technique is safe without increased complications. A significant portion of these patients was able to wean off supplemental enteral feeding assistance by a year after g-tube placement.

Human Mesenchymal Stem Cell Hydrogen Sulfide Production Critically Impacts the Release of Other Paracrine Mediators After Injury.

BACKGROUND: The use of mesenchymal stem cells (MSCs) for treatment during ischemia is novel. Hydrogen sulfide (H2S) is an important paracrine mediator that is released from MSCs to facilitate angiogenesis and vasodilation. Three enzymes, cystathionine-beta-synthase (CBS), cystathionine-gamma-lyase (CSE), and 3-mercaptopyruvate-sulfurtransferase (MPST), are mainly responsible for H2S production. However, it is unclear how these enzymes impact the production of other critical growth factors and chemokines. We hypothesized that the enzymes responsible for H2S production in human MSCs would also critically regulate other growth factors and chemokines. MATERIALS AND METHODS: Human MSCs were transfected with CBS, MPST, CSE, or negative control small interfering RNA. Knockdown of enzymes was confirmed by polymerase chain reaction. Cells were plated in 12-well plates at 100,000 cells per well and stimulated with tumor necrosis factor-α (TNF-α; 50 ng/mL), lipopolysaccharide (LPS; 200 ng/mL), or 5% hypoxia for 24 h. Supernatants were collected, and cytokines measured by multiplex beaded assay. Data were compared with the Mann-Whitney U-test, and P < 0.05 was significant. RESULTS: TNF-α, LPS, and hypoxia effectively stimulated MSCs. Granulocyte colony-stimulating factor (GCSF), epidermal growth factor, fibroblast growth factor, granulocyte/monocyte colony-stimulating factor (GMCSF), vascular endothelial growth factor, and interferon gamma-inducible protein 10 were all significantly elevated when CSE was knocked down during TNF-α stimulation (P < 0.05). Knockdown of MPST during LPS stimulation more readily increased GCSF and epidermal growth factor but decreased GMCSF (P < 0.05). CBS knockdown decreased production of GCSF, fibroblast growth factor, GMCSF, and vascular endothelial growth factor (P < 0.05) after hypoxia. CONCLUSIONS: The enzymes that produce H2S in MSCs are also responsible for the production of other stem cell paracrine mediators under stressful stimuli. Therefore, reprogramming MSCs to endogenously produce more H2S as a therapeutic intervention could also critically impact other paracrine mediators, which may alter the desired beneficial effects.

Outcomes for Correction of Long-Gap Esophageal Atresia: A 22-Year Experience.

BACKGROUND: Long-gap esophageal atresia (LGEA) precludes immediate primary repair. When delayed primary esophagoesophagostomy (DPE) is not feasible, a reverse gastric tube (RGT) is a potential salvage option. The purpose of this study was to determine if DPE and RGT had both similar short-term and long-term outcomes. METHODS: A retrospective review of all EA patients from 1994 to 2016 was undertaken. Data were stratified by surgical management (DPE versus RGT). Baseline demographics, operative information, postoperative management, and complications were analyzed. Descriptive statistics were used and P-values <0.05 were considered statistically significant. RESULTS: Two hundred and eighteen patients with EA were treated during this period; 37/218 (17%) had LGEA. Mean gap length was 3.3 ± 1.2 cm. Thirty-three patients underwent some form of repair, all of which were managed initially with a gastrostomy tube feeds. Twenty-five patients underwent DPE with 89% of these never requiring revision, and 86% having excellent function with long-term follow-up. In eight patients, esophageal length was never adequate for DPE; therefore, six were reconstructed with RGT, and two underwent gastric transposition. There were no significant differences in complications, revisions, ventilator days, overall length of stay, weight percentiles, or conduit function between children undergoing RGT compared with DPE at a mean follow-up of 5.5 years. CONCLUSIONS: Surgical treatment of LGEA is complex, and controversy exists regarding the optimal repair method when DPE is not feasible. In this series, DPE after gastrostomy tube feeds often allowed for sufficient esophageal lengthening with satisfactory long-term esophageal function. However, when adequate length for DPE was not attainable, these data suggest that RGT is a viable conduit with favorable postoperative outcomes.

Stem Cell Therapy and Hydrogen Sulfide: Conventional or Nonconventional Mechanisms of Action?

PURPOSE: Hydrogen sulfide (H2S) has many beneficial biological properties, including the ability to promote vasodilation. It has been shown to be released from stem cells and increased by hypoxia. Therefore, H2S may be an important paracrine factor in stem cell-mediated intestinal protection. We hypothesized that H2S created through conventional pathways would be a critical component of stem cell-mediated intestinal protection after ischemic injury. METHODS: Human bone marrow-derived mesenchymal stem cells (BMSCs) were transfected with negative control siRNA (Scramble), or with siRNA to CBS, MPST, or CTH. Knockdown was confirmed with PCR and H2S gas assessed with AzMC fluorophore. Eight-week-old male mice then underwent intestinal ischemia for 60 min, after which time, perfusion was restored. BMSCs from each of the above groups were then placed into the mouse abdominal cavity before final closure. After 24 h, mice were reanesthetized and mesenteric perfusion was assessed by Laser Doppler Imaging (LDI). Animals were then sacrificed and intestines excised, placed in formalin, paraffin embedded, and stained with H & E. Intestines were then scored with a common mucosal injury grading scale. RESULTS: PCR confirmed knockdown of conventional H2S-producing enzymes (CBS, MPST, CTH). H2S gas was decreased in MPST and CTH-transfected cells in normoxic conditions, but was not decreased compared with Scramble in any of the transfected groups in hypoxic conditions. BMSCs promoted increased mesenteric perfusion at 24 h postischemia compared with vehicle. Transfected stem cells provided equivalent protection. Histologic injury was improved with BMSCs compared with vehicle. CBS, MPST, and CTH knockdown cell lines did not have any worse histological injury compared with Scramble. CONCLUSIONS: Knocking down conventional H2S-producing enzymes only impacted gas production in normoxic conditions. When cells were transfected in hypoxic conditions, as would be expected in the ischemic intestines, H2S gas was not depressed. These data, along with unchanged perfusion and histological injury parameters with conventional enzyme knockdown, would indicate that alternative H2S production pathways may be initiated during hypoxic and/or ischemic events.

Bone Marrow-Derived Cells Restore Functional Integrity of the Gut Epithelial and Vascular Barriers in a Model of Diabetes and ACE2 Deficiency.

RATIONALE: There is incomplete knowledge of the impact of bone marrow cells on the gut microbiome and gut barrier function. OBJECTIVE: We postulated that diabetes mellitus and systemic ACE2 (angiotensin-converting enzyme 2) deficiency would synergize to adversely impact both the microbiome and gut barrier function. METHODS AND RESULTS: Bacterial 16S rRNA sequencing and metatranscriptomic analysis were performed on fecal samples from wild-type, ACE2-/y, Akita (type 1 diabetes mellitus), and ACE2-/y-Akita mice. Gut barrier integrity was assessed by immunofluorescence, and bone marrow cell extravasation into the small intestine was evaluated by flow cytometry. In the ACE2-/y-Akita or Akita mice, the disrupted barrier was associated with reduced levels of myeloid angiogenic cells, but no increase in inflammatory monocytes was observed within the gut parenchyma. Genomic and metatranscriptomic analysis of the microbiome of ACE2-/y-Akita mice demonstrated a marked increase in peptidoglycan-producing bacteria. When compared with control cohorts treated with saline, intraperitoneal administration of myeloid angiogenic cells significantly decreased the microbiome gene expression associated with peptidoglycan biosynthesis and restored epithelial and endothelial gut barrier integrity. Also indicative of diabetic gut barrier dysfunction, increased levels of peptidoglycan and FABP-2 (intestinal fatty acid-binding protein 2) were observed in plasma of human subjects with type 1 diabetes mellitus (n=21) and type 2 diabetes mellitus (n=23) compared with nondiabetic controls (n=23). Using human retinal endothelial cells, we determined that peptidoglycan activates a noncanonical TLR-2 (Toll-like receptor 2) associated MyD88 (myeloid differentiation primary response protein 88)-ARNO (ADP-ribosylation factor nucleotide-binding site opener)-ARF6 (ADP-ribosylation factor 6) signaling cascade, resulting in destabilization of p120-catenin and internalization of VE-cadherin as a mechanism of deleterious impact of peptidoglycan on the endothelium. CONCLUSIONS: We demonstrate for the first time that the defect in gut barrier function and dysbiosis in ACE2-/y-Akita mice can be favorably impacted by exogenous administration of myeloid angiogenic cells.

Hydrogen Sulfide Donor GYY4137 Acts Through Endothelial Nitric Oxide to Protect Intestine in Murine Models of Necrotizing Enterocolitis and Intestinal Ischemia.

BACKGROUND: Necrotizing enterocolitis (NEC) in premature infants is often a devastating surgical condition with poor outcomes. GYY4137 is a long-acting donor of hydrogen sulfide, a gasotransmitter that is protective against intestinal injury in experimental NEC, likely through protection against injury secondary to ischemia. We hypothesized that administration of GYY4137 would improve mesenteric perfusion, reduce intestinal injury, and reduce inflammatory responses in experimental NEC and ischemia-reperfusion injury, and that these benefits would be mediated through endothelial nitric oxide synthase-dependent pathways. METHODS: NEC was induced in C57BL/6 wild-type (WT) and endothelial nitric oxide synthase (eNOS) knockout (eNOSKO) pups via maternal separation, formula feeding, enteral lipopolysaccharide, and intermittent hypoxic and hypothermic stress. Pups received daily intraperitoneal injections of 50 mg/kg GYY4137 or phosphate buffered saline vehicle. In separate groups, adult male WT and eNOSKO mice underwent superior mesenteric artery occlusion for 60 min. Before abdominal closure, 50 mg/kg GYY4137 or phosphate buffered saline vehicle was administered into the peritoneal cavity. Laser doppler imaging was used to assess mesenteric perfusion of pups at baseline and on postnatal day 9, and the adult mice at baseline and 24 h after ischemic insult. After euthanasia, the terminal ileum of each animal was fixed, paraffin embedded, sectioned, and stained with hematoxylin and eosin. Sections were blindly graded using published injury scores. Intestinal tissue was homogenized and cytokines measured by ELISA. Data were compared using Mann-Whitney U test, and P-values <0.05 were significant. RESULTS: After NEC and ischemia reperfusion (I/R) injury, GYY4137 improved perfusion in WT mice compared to vehicle, but this effect was lost in the eNOSKO animals. Histologic injury followed a similar pattern with reduced intestinal injury in WT mice treated with GYY4137, and no significant improvement in the eNOSKO group. Cytokine expression after GYY4137 administration was altered by the ablation of eNOS in both NEC and I/R injury groups, with significant differences noted in Interleukin 6 and vascular endothelial growth factor. CONCLUSIONS: GYY4137, a long-acting donor of hydrogen sulfide, has potential as a therapeutic compound for NEC. It improves mesenteric perfusion and intestinal injury in experimental NEC and intestinal I/R injury, and these benefits appear to be mediated through eNOS-dependent pathways.

Loss of endothelial nitric oxide synthase exacerbates intestinal and lung injury in experimental necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) continues to be a devastating condition among preterm infants. Nitric oxide, which is synthesized in the intestine by endothelial nitric oxide synthase (eNOS), acts as a potent vasodilator and antioxidant within the mesentery and may play a role in prevention of NEC. We hypothesized that loss of endothelial nitric oxide would worsen both intestinal and associated lung injury and increase local and systemic inflammation during experimental NEC. METHODS: NEC was induced in five-day-old wild type (WT) and eNOS-knockout (eNOSKO) mouse pups. Experimental groups (n=10) were formula fed and subjected to intermittent hypoxic and hypothermic stress, while control groups (n=10) remained with their mother to breastfeed. Pups were monitored by daily clinical assessment. After sacrifice on day nine, intestine and lung were assessed for injury, and cytokines were measured in tissue homogenates by ELISA. Data were compared with Mann-Whitney, and p<0.05 was significant. RESULTS: Each NEC group was compared to its respective strain's breastfed control to facilitate comparisons between the groups. Both NEC groups were significantly sicker than their breastfed controls. eNOSKO NEC animals had a median clinical assessment score of 3 (IQR=1-5), and the WT NEC animal's median score was 3 (IQR=2-5). Despite similar clinical scores, intestinal injury was significantly worse in the eNOSKO NEC groups compared to WT NEC groups (median injury scores of 3.25 (IQR=2.25-3.625) and 2 (IQR=1-3), respectively (p=0.0474). Associated lung injury was significantly worse in the eNOSKO NEC group as compared to the WT NEC group (median scores of 8.5 (IQR=6.75-11.25) and 6.5 (IQR=5-7.5), respectively, p=0.0391). Interestingly, cytokines in both tissues were very different between the two groups, with varying effects noted for each cytokine (IL-6, IL-1ß, VEGF, and IL-12) in both tissues. CONCLUSION: Nitric oxide from eNOS plays a key role in preventing the development of NEC. Without eNOS function, both intestinal and lung injuries are more severe, and the inflammatory cascade is significantly altered. Further studies are needed to determine how eNOS-derived nitric oxide facilitates these beneficial effects.

The route and timing of hydrogen sulfide therapy critically impacts intestinal recovery following ischemia and reperfusion injury.

PURPOSE: Hydrogen sulfide (H2S) has many beneficial properties and may serve as a novel treatment in patients suffering from intestinal ischemia-reperfusion injury (I/R). The purpose of this study was to examine the method of delivery and timing of administration of H2S for intestinal therapy during ischemic injury. We hypothesized that 1) route of administration of hydrogen sulfide would impact intestinal recovery following acute mesenteric ischemia and 2) preischemic H2S conditioning using the optimal mode of administration as determined above would provide superior protection compared to postischemic application. METHODS: Male C57BL/6J mice underwent intestinal ischemia by temporary occlusion of the superior mesenteric artery. Following ischemia, animals were treated according to one of the following (N=6 per group): intraperitoneal or intravenous injection of GYY4137 (H2S-releasing donor, 50mg/kg in PBS), vehicle, inhalation of oxygen only, inhalation of 80ppm hydrogen sulfide gas. Following 24-h recovery, perfusion was assessed via laser Doppler imaging, and animals were euthanized. Perfusion and histology data were assessed, and terminal ileum samples were analyzed for cytokine production following ischemia. Once the optimal route of administration was determined, preischemic conditioning with H2S was undertaken using that route of administration. All data were analyzed using Mann-Whitney. P-values <0.05 were significant. RESULTS: Mesenteric perfusion following intestinal I/R was superior in mice treated with intraperitoneal (IP) GYY4137 (IP vehicle: 25.6±6.0 vs. IP GYY4137: 79.7±15.1; p=0.02) or intravenous (IV) GYY4137 (IV vehicle: 36.3±5.9 vs. IV GYY4137: 100.7±34.0; p=0.03). This benefit was not observed with inhaled H2S gas (O2 vehicle: 66.6±11.4 vs. H2S gas: 81.8±6.0; p=0.31). However, histological architecture was only preserved with intraperitoneal administration of GYY4127 (IP vehicle: 3.4±0.4 vs. IP GYY4137: 2±0.3; p=0.02). Additionally, IP GYY4137 allowed for significant attenuation of inflammatory chemokine production of IL-6, IP-10 and MIP-2. We then analyzed whether there was a difference between pre- and postischemic administration of IP GYY4137. We found that preconditioning of animals with intraperitoneal GYY4137 only added minor improvements in outcomes compared to postischemic application. CONCLUSION: Therapeutic benefits of H2S are superior with intraperitoneal application of an H2S donor compared to other administration routes. Additionally, while intraperitoneal treatment in both the pre- and postischemic period is beneficial, preischemic application of an H2S donor was found to be slightly better. Further studies are needed to examine long term outcomes and further mechanisms of action prior to widespread clinical application. TYPE OF STUDY: Basic science. LEVEL OF EVIDENCE: N/A.

Umbilical mesenchymal stromal cells provide intestinal protection through nitric oxide dependent pathways.

BACKGROUND: Umbilical-derived mesenchymal stromal cells (USCs) have shown promise in the protection of ischemic organs. We hypothesized that USCs would improve mesenteric perfusion, preserve intestinal histological architecture, and limit inflammation by nitric oxide-dependent mechanisms following intestinal ischemia/reperfusion (IR) injury. METHODS: Adult wild-type C57BL/6J (WT) and endothelial nitric oxide synthase knock out (eNOS KO) mice were used: (1) WT IR + vehicle, (2) WT IR + USC, (3) eNOS KO IR + vehicle, and (4) eNOS KO IR + USC. Mice were anesthetized, and a midline laparotomy was performed. The superior mesenteric artery was clamped with a nonoccluding clamp for 60-min. Following IR, mice were treated with an injection of 250 µL phosphate buffered saline or 2 × 106 USCs suspended in 250-µL phosphate buffered saline solution. Mesenteric perfusion images were acquired using laser Doppler imaging. Perfusion was analyzed as a percentage of baseline. At 24 h, mice were euthanized, and intestines were harvested. Intestines were evaluated for injury, and data were analyzed using the Mann-Whitney or Kruskal-Wallis tests. RESULTS: Intestinal mesenteric perfusion was significantly improved in WT mice treated with USC therapy compared with eNOS KOs. Intestinal histological architecture was preserved with USC therapy in WT mice. However, in eNOS KO mice, this benefit was abolished. Finally, the presence of several cytokines and growth factors were significantly improved in WT mice compared with eNOS KO mice treated with USCs. CONCLUSIONS: The benefits of USC-mediated therapy following intestinal IR injury likely occur via nitric oxide-dependent pathways. Further studies are required to define the molecular mechanisms by which USCs activate endothelial nitric oxide synthase to bring about their protective effects.

Hydrogen sulfide provides intestinal protection during a murine model of experimental necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) continues to be a morbid surgical condition among preterm infants. Novel therapies for this condition are desperately needed. Hydrogen sulfide (H2S) is an endogenous gasotransmitter that has been found to have beneficial properties. We therefore hypothesized that intraperitoneal injection of various H2S donors would improve clinical outcomes, increase intestinal perfusion, and reduce intestinal injury in an experimental mouse model of necrotizing enterocolitis. METHODS: NEC was induced in five-day-old mouse C57BL/6 mouse pups through maternal separation, formula feeding, and intermittent hypoxic and hypothermic stress. The control group (n=10) remained with their mother and breastfed ad lib. Experimental groups (n=10/group) received intraperitoneal injections of phosphate buffered saline (PBS) vehicle or one of the following H2S donors: (1) GYY4137, 50mg/kg daily; (2) Sodium sulfide (Na2S), 20mg/kg three times daily; (3) AP39, 0.16mg/kg daily. Pups were monitored for weight gain, clinical status, and intestinal perfusion via transcutaneous Laser Doppler Imaging (LDI). After sacrifice on day nine, intestinal appearance and histology were scored and cytokines were measured in tissue homogenates of intestine, liver, and lung. Data were compared with Mann-Whitney and p<0.05 was considered significant. RESULTS: Clinical score and weight gain were significantly improved in all three H2S-treated groups as compared to vehicle (p<0.05 for all groups). Intestinal perfusion of the vehicle group was 22% of baseline while the GYY4137 group was 38.7% (p=0.0103), Na2S was 47.0% (p=0.0040), and AP39 was 43.0% (p=0.0018). The vehicle group had a median histology score of 2.5, while the GYY4137 group's was 1 (p=0.0013), Na2S was 0.5 (p=0.0004), and AP39 was 0.5 (p=0.0001). Cytokine analysis of the intestine of the H2S-treated groups revealed levels closer to breastfed pups as compared to vehicle (p<0.05 for all groups). CONCLUSION: Intraperitoneal administration of H2S protects against development of NEC by improving mesenteric perfusion, and by limiting mucosal injury and altering the tissue inflammatory response. Further experimentation is necessary to elucidate downstream mechanisms prior to clinical implementation.

Why wait: early enteral feeding after pediatric gastrostomy tube placement.

PURPOSE: Early initiation of feedings after gastrostomy tube (GT) placement may reduce associated hospital costs, but many surgeons fear complications could result from earlier feeds. We hypothesized that, irrespective of placement method, starting feedings within the first 6h following GT placement would not result in a greater number of post-operative complications. METHODS: An IRB-approved retrospective review of all GTs placed between January 2012 and December 2014 at three academic institutions was undertaken. Data was stratified by placement method and whether the patient was initiated on feeds at less than 6h or after. Baseline demographics, operative variables, post-operative management and complications were analyzed. Descriptive statistics were used and P-values <0.05 were considered significant. RESULTS: One thousand and forty-eight patients met inclusion criteria. GTs were inserted endoscopically (48.9%), laparoscopically (44.9%), or via an open approach (6.2%). Demographics were similar in early and late fed groups. When controlling for method of placement, those patients who were fed within the first 6h after gastrostomy placement had shorter lengths of stay compared to those fed greater than 6h after placement (P<0.05). Total post-operative outcomes were equivalent between feeding groups for all methods of placement (laparoscopic (P=0.87), PEG (P=0.94), open (P=0.81)). CONCLUSIONS: Early initiation of feedings following GT placement was not associated with an increase in complications. Feeds initiated earlier may shorten hospital stays and decrease overall hospital costs. TYPE OF STUDY: Multi-institutional retrospective. LEVEL OF EVIDENCE: III.

Direct peritoneal resuscitation improves mesenteric perfusion by nitric oxide dependent pathways.

BACKGROUND: Direct peritoneal resuscitation (DPR) has been shown to increase survival after intestinal ischemia and reperfusion injury (I/R). We have previously appreciated that minimum essential medium (MEM), a synthetic cell culture medium with bovine serum, glutamine, and antibiotics, contributes to these benefits. We hypothesized that (1) DPR using MEM as a dialysate would increase mesenteric perfusion, improve intestinal mucosal injury, and limit intestinal and hepatic inflammation after intestinal I/R and (2) these improvements would be dependent on endothelial nitric oxide pathways. METHODS: Eight-week-old C57Bl6J wild-type (WT) and eNOS Knock Out (eNOS KO) male mice were anesthetized and intestinal ischemia was induced for 60 min. After ischemia, 1 mL of phosphate buffered saline vehicle or MEM was injected into the abdominal cavity. Intestinal perfusion was reassessed after 48 h. Animals were then euthanized, and intestines and livers explanted for histologic and molecular analyses. RESULTS: DPR with MEM significantly improved mesenteric perfusion compared with vehicle (phosphate buffered saline) as measured by Laser Doppler Imaging (WT + MEM 91.58 ± 13.74%, WT + Vehicle 44.27 ± 11.93%, P < 0.05); however, these benefits were lost when endothelial nitric oxide signaling pathways were ablated (eNOS KO + MEM 21.72 ± 5.67 %, eNOS KO + Vehicle 45.24± 11.31%). WT mice treated with MEM also had significantly better preservation of their mucosal architecture (WT + MEM Mdn = 1.0, interquartile range [IQR] = 1.25, WT + Vehicle Mdn = 3.0, IQR = 2.0, P < 0.05). When we compared eNOS KO mice treated with either MEM or vehicle the protective effect of MEM disappeared (eNOS KO + MEM Mdn = 2.0, IQR = 2.25, eNOS KO + Vehicle Mdn = 2.0, IQR = 1.0 P > 0.05). Intestinal levels of interleukin (IL)-1ß were increased in WT animals treated with MEM compared with eNOS KOs, whereas concentrations of intestinal IL-6 were similar between groups. Hepatic levels of both IL-1ß and IL-6 were significantly elevated in eNOS KOs compared with WT treated with MEM. CONCLUSIONS: DPR with MEM has significant therapeutic potential for improving mesenteric perfusion, intestinal injury, and the local inflammatory response after intestinal I/R. These benefits appear to be dependent on nitric oxide signaling within the endothelium.

Hydrogen Sulfide: A Potential Novel Therapy for the Treatment of Ischemia.

Hydrogen sulfide (H2S) is a novel signaling molecule most recently found to be of fundamental importance in cellular function as a regulator of apoptosis, inflammation, and perfusion. Mechanisms of endogenous H2S signaling are poorly understood; however, signal transmission is thought to occur via persulfidation at reactive cysteine residues on proteins. Although much has been discovered about how H2S is synthesized in the body, less is known about how it is metabolized. Recent studies have discovered a multitude of different targets for H2S therapy, including those related to protein modification, intracellular signaling, and ion channel depolarization. The most difficult part of studying hydrogen sulfide has been finding a way to accurately and reproducibly measure it. The purpose of this review is to: elaborate on the biosynthesis and catabolism of H2S in the human body, review current knowledge of the mechanisms of action of this gas in relation to ischemic injury, define strategies for physiological measurement of H2S in biological systems, and review potential novel therapies that use H2S for treatment.

Hydrogen sulfide improves intestinal recovery following ischemia by endothelial nitric oxide-dependent mechanisms.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter that has vasodilatory properties. It may be a novel therapy for intestinal ischemia-reperfusion (I/R) injury. We hypothesized that 1) H2S would improve postischemic survival, mesenteric perfusion, mucosal injury, and inflammation compared with vehicle and 2) the benefits of H2S would be mediated through endothelial nitric oxide. C57BL/6J wild-type and endothelial nitric oxide synthase knockout (eNOS KO) mice were anesthetized, and a midline laparotomy was performed. Intestines were eviscerated, the small bowel mesenteric root identified, and baseline intestinal perfusion was determined using laser Doppler. Intestinal ischemia was established by temporarily occluding the superior mesenteric artery. Following ischemia, the clamp was removed, and the intestines were allowed to recover. Either sodium hydrosulfide (2 nmol/kg or 2 µmol/kg NaHS) in PBS vehicle or vehicle only was injected into the peritoneum. Animals were allowed to recover and were assessed for mesenteric perfusion, mucosal injury, and intestinal cytokines. P values < 0.05 were significant. H2S improved mesenteric perfusion and mucosal injury scores following I/R injury. However, in the setting of eNOS ablation, there was no improvement in these parameters with H2S therapy. Application of H2S also resulted in lower levels of intestinal cytokine production following I/R. Intraperitoneal H2S therapy can improve mesenteric perfusion, intestinal mucosal injury, and intestinal inflammation following I/R. The benefits of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.NEW & NOTEWORTHY H2S is a gaseous mediator that acts as an anti-inflammatory agent contributing to gastrointestinal mucosal defense. It promotes vascular dilation, mucosal repair, and resolution of inflammation following intestinal ischemia and may be exploited as a novel therapeutic agent. It is unclear whether H2S works through nitric oxide-dependent pathways in the intestine. We appreciate that H2S was able to improve postischemic recovery of mesenteric perfusion, mucosal integrity, and inflammation. The beneficial effects of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.