Increased Transit Time Research Articles

Decreases in mucosally-evoked tachykinin signaling pathways can explain age-related reductions in murine colonic motility patterns.

Increasing age increases the incidence of chronic constipation and fecal impaction. The contribution of the natural aging process to this phenotype is unclear. This study explored the effects of age on key motility patterns in the murine colon and determined the contribution that altered neurokinin 2 (NK2) -mediated signaling made to the aging phenotype. Mucosal reflexes, colonic migrating motor complexes (CMMCs) and colonic motility assays were explored in isolated exvivo colons from 3, 12-14, 18- and 24-months old mice and the NK2-mediated response determined. Electrical field stimulation (EFS) or exogenous drug application were used to explore the role of the mucosa in colonic segments. Aging reduced the force of contraction of the distal colon mucosal reflex, the frequency and force of contraction of CMMCs and the NK2-mediated component of both motility patterns. Ondansetron, a 5-HT3 receptor antagonist, blocked a component of both motility patterns in full thickness but not in mucosa-free segments of the distal colon. 5, hydroxytryptamine (5-HT) and EFS-evoked NK2-dependent contractions were reduced with increasing age. Smooth muscle sensitivity to 5-HT or neurokinin A (NKA) was not altered with age. In isolated colon motility assays application of NKA decreased transit time in 24-months colon and the NK2 antagonist GR159897 increased transit times in both 3- and 24-months old colons. Aging impairs key motility patterns in the murine colon. These changes involve a decrease in mucosally-evoked NK2-mediated signaling. Targeting NK2-mediated signaling may provide a novel approach to treating age-related motility disorders in the lower bowel.

Investigating the influence of sub-mesoscale current structures on Baltic Sea connectivity through a Lagrangian analysis

This study explores the impact of sub-mesoscale structures and vertical advection on the connectivity properties of the Baltic Sea using a Lagrangian approach. High-resolution flow fields from the General Estuarine Transport Model (GETM) were employed to compute Lagrangian trajectories, focusing on the influence of fine-scale structures on connectivity estimates. Six river mouths in the Baltic Sea served as initial positions for numerical particles, and trajectories were generated using flow fields with varying horizontal resolutions: 3D trajectories with 250m resolution as well as 2D trajectories with 250m and 1km resolutions. Several Lagrangian indices, such as mean transit time, arrival depths, and probability density functions of transit times, were analyzed to unravel the complex circulation of the Baltic Sea and highlight the substantial impact of sub-mesoscale structures on numerical trajectories. Results indicate that in 2D simulations, particles exhibit faster movement on the eastern side of the Gotland Basin in high-resolution compared to coarse-resolution simulations. This difference is attributed to the stronger coastal current in high-resolution compared to coarse-resolution simulations. Additionally, the study investigates the influence of vertical advection on numerical particle motion within the Baltic Sea, considering the difference between 3D and 2D trajectories. Findings reveal that denser water in the eastern and south-eastern areas significantly affects particle dispersion in 3D simulations, resulting in increased transit times. Conversely, regions in the North-western part of the basin accelerate particle movement in 3D compared to the 2D simulations. Finally, we calculated the average residence time of numerical particles exiting the Baltic Sea through the Danish strait. Results show an average surface layer residence time of approximately 790 days over an eight-year integration period, highlighting the relatively slow water circulation in the semi-enclosed Baltic Sea basin. This prolonged residence time emphasizes the potential for the accumulation of pollutants. Overall, the study underscores the pivotal role of fine-scale structures in shaping the connectivity of the Baltic Sea, with implications for understanding and managing environmental challenges in this unique marine ecosystem.

The decreased interface tension increased the transmembrane transport of soy hull polysaccharide-derived SCFAs in the Caco-2 cells

Polysaccharides impact intestinal fermentation and regulate interfacial properties which affect absorption and transportation. Short-chain fatty acids (SCFAs), the main metabolites of soy hull polysaccharide lysate, are readily absorbed by the body and perform various physiological functions. We analysed the interfacial properties and transport of soy hull polysaccharide-derived SCFAs in the Caco-2 cell model to clarify the transmembrane transport mechanism. The results showed that the interfacial properties of the co-culture system were influenced by both transit time and concentration of SCFAs, the uptake and transit rates of SCFAs at 1–3 h increased significantly with time (P < 0.05). With increasing transit time and concentration, the transit rates of SCFAs on the apical side (AP) → basolateral side (BL) and BL → AP sides increased and then stabilised, the transit rate of the AP → BL side was higher than that of the BL → AP side. Proteomic analysis showed that soy hull polysaccharide-derived SCFAs resulted in the differential expression of 285 upregulated and 501 downregulated after translocation across Caco-2 cells. The differentially expressed proteins were mainly enriched in ribosomes, oxidative phosphorylation, nuclear transport, and SNARE vesicular transport. This study lays the theoretical foundation for understanding the structure-activity relationship of soy hull polysaccharides in the intestine.

Glucagon-like Peptide-2 Depresses Ileal Contractility in Preparations from Mice through Opposite Modulatory Effects on Nitrergic and Cholinergic Neurotransmission.

Glucagon-like peptide-2 (GLP-2) has been reported to influence gastrointestinal motor responses, exerting a modulatory role on enteric neurotransmission. To our knowledge, no data on GLP-2 effects on the motility of the isolated ileum are available; therefore, we investigated whether GLP-2 affects the contractile activity of mouse ileal preparations and the neurotransmitters engaged. Ileal preparations showed tetrodotoxin (TTX)- and atropine-insensitive spontaneous contractile activity, which was unaffected by the nitric oxide synthesis inhibitor, L-NNA. GLP-2 depressed the spontaneous contractility, an effect that was abolished by TTX or L-NNA and not influenced by atropine. Electrical field stimulation induced TTX- and atropine-sensitive contractile responses, which were reduced in amplitude by GLP-2 even in the presence of L-NNA. Immunohistochemical results showed a significant increase in nNOS-positive fibers in the ileal muscle wall and a significant decrease in ChAT-positive myenteric neurons in GLP-2-exposed preparations. The present results offer the first evidence that GLP-2 acts on ileal preparations. The hormone appears to depress ileal contractility through a dual opposite modulatory effect on inhibitory nitrergic and excitatory cholinergic neurotransmission. From a physiological point of view, it could be hypothesized that GLP-2 inhibitory actions on ileal contractility can increase transit time, facilitating nutrient absorption.

Rural and Urban EMS Level of Comfort with Overdose Treatment

Purpose: This study aims to determine aptitude levels of rural and urban EMS providers treating drug overdoses in the field. Methods: This is both a qualitative and quantitative cross-sectional survey including 90 respondents from urban and rural demographics. Findings: This study found no evidence (p = 0.126) that the likelihood of being extremely comfortable with administering Naloxone differed between urban and rural EMS workers when accounting for certification level, years of experience and amount of training. We also found no evidence (p = 0.859) of a difference between rural and urban EMS workers administering secondary doses of naloxone. Conclusion: This study demonstrated that although rural EMS providers have an increased transit time to get an overdose patient to the hospital and were less likely to have an advanced provider available to them at the response scene, rural providers feel similarly comfortable with treating an opioid overdose with naloxone as their urban counterparts when certification level, years of experience and number of hours of training are considered.

Impacts of the COVID-19 pandemic on a human research islet program

ABSTRACT Designated a pandemic in March 2020, the spread of severe acute respiratory syndrome virus 2 (SARS-CoV2), the virus responsible for coronavirus disease 2019 (COVID-19), led to new guidelines and restrictions being implemented for individuals, businesses, and societies in efforts to limit the impacts of COVID-19 on personal health and healthcare systems. Here we report the impacts of the COVID-19 pandemic on pancreas processing and islet isolation/distribution outcomes at the Alberta Diabetes Institute IsletCore, a facility specializing in the processing and distribution of human pancreatic islets for research. While the number of organs processed was significantly reduced, organ quality and the function of cellular outputs were minimally impacted during the pandemic when compared to an equivalent period immediately prior. Despite the maintained quality of isolated islets, feedback from recipient groups was more negative. Our findings suggest this is likely due to disrupted distribution which led to increased transit times to recipient labs, particularly those overseas. Thus, to improve overall outcomes in a climate of limited research islet supply, prioritization of tissue recipients based on likely tissue transit times may be needed.

The fetal lamb model of congenital diaphragmatic hernia shows altered cerebral perfusion using contrast enhanced ultrasound

BackgroundNeurodevelopmental impairment is common in survivors of congenital diaphragmatic hernia (CDH). Altered cerebral perfusion in utero may contribute to abnormal brain development in CDH patients. Methods5 fetal lambs with surgical left-CDH and 5 controls underwent transuterine cranial Doppler and contrast enhanced ultrasound (CEUS). Global and regional perfusion metrics were obtained. Biometric and perfusion data were compared between groups via nonparametric Mann Whitney U test and Spearman's rank order correlation. ResultsNo significant differences in cerebral Doppler measurements were identified between groups. By CEUS, CDH animals demonstrated significantly decreased global brain perfusion and increased transit time. With focal regions-of-interest (ROIs), there was a tendency towards decreased perfusion in the central/thalamic region in CDH but not in the peripheral brain parenchyma. Transit time was significantly increased in both ROIs in CDH, whereas flux rate was decreased in the central/thalamic region but not the peripheral brain parenchyma. Biometric CDH severity was correlated to perfusion deficit. There was no difference in cardiomyocyte histology. ConclusionThe fetal lamb model of CDH shows altered cerebral perfusion as measured by CEUS, correlating to disease severity. This suggests a physiological abnormality in fetal cerebrovascular perfusion that may contribute to abnormal brain development and neurodevelopmental impairment in survivors.

Review study on carbohydrates and fibre

The diets high in fibre such as cereals, nuts, fruits and vegetables have a beneficial impact on health because their intake has been linked to reduced incidence of many illnesses. The diets with high concentration of fibre have been found to have a beneficial impact on health. During processing the foods undergo different physical, chemical, enzymatic and thermal treatments, which directly or in directly influence the composition of total fiber in the past, carbohydrates have been regarded of merely as a source of energy and fibre. However, recent research has revealed a myriad of photoactive chemicals contained within fibre fractions of carbohydrates, as well as a wide range of beneficial physiological functions (such as increased transit time, production of short chain fatty acids, increased satiety etc.) which can be ascribed to various substances found in carbohydrates. This study highlights the function of carbs in health and looks at the various kinds of carbohydrates, current dietary consumption, and the effect of fibre on prevention of cancer, heart disease and weight gain. In addition, the study examines the prebiotic activity of resistant starches.

Transplantation of allogeneic cryopreserved hematopoietic cell grafts during the Covid-19 pandemic: A National Marrow Donor Program perspective.

Transplantation of allogeneic cryopreserved hematopoietic cell grafts during the Covid-19 pandemic: A National Marrow Donor Program perspective.

Persea Americana Seeds Cause Ileal Smooth Muscle Relaxation Via Stimulation of α-1 Adrenoceptors

The effect of methanol extract of P. americana seeds on isolated ileal smooth muscle was studied for isometric response using 10 adult rabbits of both sexes. Reactivity and agonist-antagonist responses of rabbit ileum to the extract were determined in this study. The affinity, effective concentration to give 50% response (EC50) and maximum response were calculated from the concentration response curves (CRC) obtained. The result for the reactivity study showed the seed extract of P. americana caused concentration dependent relaxation of isolated rabbit ileum with threshold responses at concentration of 1×10-9 mg/ml and 120 mg/ml respectively. The extract-antagonist study showed an upward and right shift in CRC in the presence of phenoxybenzamine, a non-selective adrenergic antagonist, with the EC50 increased from 5.01 mg/ml to 12.59 mg/ml and affinity decreased from 0.20 to 0.08. Extract-antagonist study also showed a right and upward shift in the CRC with a greater magnitude in the presence of prazosin, an α1-adrenergic antagonist, with EC50 increased from 0.32 mg/ml to 25.12 mg/ml and a consequential decrease in the affinity from 3.13 to 0.04. In the presence of propranolol, a β-adrenergic antagonist, a downward and left shift in the CRC was observed with the EC50 and PA2 remaining constant at 0.1 mg/ml and 10 respectively. P. americana concentration-dependently reduced or inhibited gastric motility, increasing transit time which is important for food absorption, thus a pro-nutritive and antispasmodic effect. The interaction with α1-adrenoceptors is beneficially in heart failure management. The plant can be developed as a drug candidate for management of hypertension.

In Vivo reconstruction of Human Erythropoiesis with Circulating Mature Human RBCs in Humanized Liver Mistrg Mice

The murine host has remained a readily available and ethically acceptable model for the study of human diseases and therapeutic testing. Immunodeficient mouse models support engraftment of human hematopoietic stem cells (HSC) but with limitation in efficiency and mature lineage representation. Combined knock-in of several non-crossreactive human cytokines (M-CSF, IL3/GM-CSF, and Thrombopoietin) into the corresponding murine loci in the SRG strain (in short termed "MISTRG") has enhanced engraftment and maintenance of human HSCs with multi-lineage differentiation (Rongvaux et al. Annu Rev Immunol 2013, Deng et al. Nature 2015, Saito et al. Blood 2016, Theocharides et al. Haematologica 2016). Despite robust HSC engraftment and myelo- and erythropoiesis in bone marrow (BM), all humanized immunodeficient mouse models lack of mature human red blood cells (RBC), platelets, and myeloid cells in peripheral blood (PB) (Rahmig et al. Stem Cell Reports 2016, Yurino et al. Stem Cell Reports 2016, Song et al. Nat Commun 2019). Yet, full maturation and representation of all myeloid lineages in PB is essential to study diseases of the HSC, such as MDS, and of the RBC, such as sickle cell anemia or malaria. With universal absence of a murine adaptive immune system the culprit is likely the murine host's innate immune system. Previous studies have shown that treatment of engrafted mice with liposomal clodronate that abrogates murine (and human) macrophages, with or without cobra venom factor that eliminates complement, can increase mature human circulating RBC, but only transiently and with significant toxicity. We first sought to determine the site of huRBC sequestration and destruction. Intravital imaging after injection of CFSE labelled huRBC identified the murine liver as the major site of RBC destruction. While muRBC rapidly circulate through the liver circulation, huRBC have greatly increased transit times and are sequestered in liver vessels. We hypothesized that humanization of the murine host's liver could potentially alleviate huRBC sequestration and significantly increase circulating huRBC. In previous studies deletion of fumarylacetoacetate hydrolase (Fah) in the Rag-/-Il2rg-/- background has allowed humanization of the liver and served to study diseases such as malaria (Vaughan et al. J Clin Invest 2012). The liver is the site of synthesis of numerous proteins, some of which directly impact hematopoiesis and blood cells, such as complement. We deleted the Fah gene via CRISPR/Cas9 in MISTRG mice and crossed MISTRG-Fah-/- mice to homozygosity (MISTRGFah). MISTRGFah are viable, fertile, and healthy when maintained on drinking water supplemented with 2-(2-nitro-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC), that blocks tyrosine metabolism upstream of Fah and prevents buildup of hepatotoxic metabolites. At 8 weeks of age we implanted MISTRGFah mice with commercially available, adult human hepatocytes (HuHep) via direct injection into the splenic vein, followed by gradual withdrawal of NTBC water. Regulated buildup of intracellular fumarylacetoacetate results in death of murine Fah-/- hepatocytes and regeneration with HuHep with up to 90% repopulation by HuHep (Azuma et al. Nature biotechnology 2007). When plasma human albumin levels reached 2mg/dL, indicative of significant (~80%) HuHep repopulation, we sublethally (80cGy) irradiated HuHepMISTRGFah mice and engrafted each mouse with 105 fetal liver (FL) derived CD34+ cells. 10 weeks post transplantation, mice were analyzed for engraftment and specifically erythroid maturation in PB. HuHepMISTRGFah mice had significantly higher levels of BM and interestingly spleen erythropoiesis and circulating huRBC in PB (Fig.1 a). CD235a+ huRBC in HuHepMISTRGFah mice are enucleated (Hoechst neg) and mature as evident by loss of CD49d (ITGA4) and gain of Band3 staining (Hu et al. Blood 2013) (Fig.1 b). Interestingly, human erythroid cells in MISTRG but not HuHepMISTRGFah mice are coated with murine complement C3 (muC3) (Fig.1 c) suggesting that liver humanization results in loss of muC3 expression. In conclusion, we have generated the first humanized mouse model with fully mature, circulating huRBC when engrafted with human CD34+ stem and progenitor cells. Ongoing studies are testing the applicability of this model to MDS and sickle cell disease. Disclosures Flavell: SMOC: Equity Ownership; Zai labs: Consultancy; GSK: Consultancy; Artizan Biosciences: Equity Ownership; Troy: Equity Ownership; Rheos Biomedicines: Equity Ownership.

Ambulatory assessment of colonic motility using the electromagnetic capsule tracking system: Effect of opioids.

Opioid treatment often causes debilitating constipation. However, it is not well described how opioids affect colonic motility and whether opioid-induced constipation is due to either a decrease of powerful peristaltic contractions or "uncoordinated" peristalsis. The present study aims to investigate the effect of oxycodone on parameters of colonic motility and to determine whether motility is normalized by the opioid antagonist naloxegol. In two randomized, double-blind crossover trials, oxycodone or placebo was administered to 25 healthy males (Trial A), while another 24 healthy males were administered oxycodone with naloxegol or placebo (Trial B). Colonic motility was assessed by tracking the progression of an electromagnetic capsule throughout the large intestine. Segmental colonic transit times and capsule movements were calculated using displacement distance and velocity. In Trial A, colonic transit time increased during oxycodone treatment compared with placebo (39 vs 18hours, P<.01). Displacement during long fast antegrade movements was shorter during oxycodone treatment than with placebo (10 vs 20cm, P=.03). In Trial B, colonic transit time was faster during oxycodone+naloxegol than during oxycodone+placebo (40 vs 55hours, P=.049), mainly caused by an increase of the percentwise fraction of distance covered by fast movements in the left colon (P=.001). Oxycodone treatment impaired colonic motility, manifested as increased transit time, specifically decreased long fast antegrade movements, and addition of naloxegol improved motility dynamics. In humans, the increased transit time during opioid treatment is caused by a decrease in long fast movements rather than uncoordinated peristalsis.

Digestive Responses to Fortified Cow or Goat Dairy Drinks: A Randomised Controlled Trial.

Fortified milk drinks are predominantly manufactured from bovine (cow) sources. Alternative formulations include those prepared with hydrolysed bovine milk proteins or from alternate bovidae species, such as caprine (goat) milk. Currently, there is little data on protein digestive and metabolic responses following ingestion of fortified milk drinks. To examine the digestive and metabolic responses to commercially-available fortified milks, young adults (n = 15 males: 15 females), in a randomised sequence, ingested isonitrogenous quantities of whole cow-protein (WC), whole goat-protein (WG), or partially-hydrolysed whey cow-protein (HC), commercial fortified milks. Plasma amino acid (AA) and hormonal responses were measured at baseline and again at 5 h after ingestion. Paracetamol recovery, breath hydrogen, and subjective digestive responses were also measured. Postprandial plasma AA was similar between WC and WG, while AA appearance was suppressed with HC. Following HC, there was a negative incremental AUC in plasma branched-chain AAs. Further, HC had delayed gastric emptying, increased transit time, and led to exaggerated insulin and GLP-1 responses, in comparison to whole protein formulas. Overall, WC and WG had similar protein and digestive responses with no differences in digestive comfort. Contrastingly, HC led to delayed gastric emptying, attenuated AA appearance, and a heightened circulating insulin response.

Analysis of Radiopaque Gastrointestinal Foreign Bodies Expelled by Spontaneous Passage in Children: A 15-Year Single-Center Study.

Background: Most ingested foreign bodies (FBs) pass spontaneously through the gastrointestinal (GI) tract, but only limited data on transit time are available. We evaluated the relationship of FB size and shape with transit time.Methods: We retrospectively reviewed medical records collected over 15 years (January 2001 to December 2015) on pediatric patients with radiopaque FBs in the GI tract. We categorized the FBs as regularly (round or spherical) or irregularly shaped (ovoid, long, flake-like, or projecting) and measured their sizes radiographically. The diameter of regularly shaped FBs and the length of irregularly shaped FBs were correlated with transit time.Results: In total, 484 patients with GI FBs were surveyed, and 267 (55.1%) FBs were radiopaque. Among the 267 radiopaque FBs, 88 (33.1%) required endoscopic removal and 7 (2.6%) underwent surgical intervention. Eighty-seven patients with single FBs in the GI tract for whom precise details of transit time were enrolled into the analysis of transit time; their mean age was 3.48 ± 2.21 years. Of the 87 FBs, 61 (70.1%) were regularly shaped, and 26 (29.9%) were irregularly shaped. The diameter of regularly shaped FBs was positively associated with transit time, as revealed by Mann-Whitney U test; diameters >1.5 and >2 cm were significantly correlated with longer transit times (both p = 0.003). A trend toward an increased transit time for long irregularly shaped FBs was also apparent; the p-values for lengths of 1.5, 2, and 2.5 cm were 0.824, 0.153, and 0.055, respectively. Under receiver operating characteristic (ROC) curve analysis, the optimal cutoff diameter for regularly shaped FBs, and length for irregularly shaped FBs, to predict a transit time of longer than 72 h were 1.95 and 2.25 cm, respectively.Conclusions: The passage rate of ingested radiopaque FBs is 64.4%. Small FBs that have passed the duodenal curve should be managed conservatively via clinical observation and radiographic surveillance. Our results indicate that the larger an FB is, the longer the transit time will be.

Can ocular administration of atropine cause colic?

Can ocular administration of atropine cause colic?

Acute Colonic Pseudo-obstruction With Pneumatosis: Neostigmine May Still Be an Option!

Case Presentation: A 35 year old female who underwent a robotic TAH/BSO for cervical cancer developed abdominal pain, bloating and obstipation on post-operative day (POD) #2. KUB revealed a pan-dilated colon with a cecum of 11 cm. GI was consulted on POD#5 due to a failure of conservative management. Examination revealed a distended, tense abdomen without bowel sounds. CT revealed pan-colonic dilation with a cecum of 9 cm with cecal pneumatosis. Acute colonic pseudo-obstruction (ACPO) and possible ischemia was diagnosed. After much deliberation regarding surgical vs. medical management, two doses of neostigmine within a 24 hour period were administered with complete resolution. Discussion: ACPO is a rare condition with unclear incidence. Risks include infection, surgery, narcotic use, and electrolyte imbalance. Symptoms include abdominal pain, distention, nausea, and vomiting. Mortality is increased with a cecum greater than 14 cm and time to decompression greater than 7 days. Treatment options vary from supportive, pharmacologic, endoscopic, and surgical therapies. Neostigmine, a reversible acetylcholinesterase inhibitor which stimulates muscarinic parasympathetic receptors to increase transit time, is effective in up to 91%, with a relapse of 38%. Colonoscopy with decompression tube is successful in up to 88%, carries a perforation risk of about 3% with a 1% mortality. Surgical intervention is associated with a 44% mortality in the setting of ischemia. Pneumatosis has long been associated with colonic ischemia. Recent radiologic research has increased our understanding of pneumatosis. No studies have looked at pneumatosis and psuedo-obstruction. Three patterns of pneumatosis have been described: Bubble like in idiopathic cases [our patient], linear type in conditions secondary to a pathologic etiology, and circular type in pulmonary disease. Conclusion: Our patient who had ACPO with bubbly type pneumatosis was effectively treated with neostigmine in efforts to avoid the risks associated with endoscopic and surgical procedures. Favorable indicators were bubbly type pneumatosis, lack of peritoneal signs, stable vital signs and a lack of acidosis. This is the first reported case of ACPO with pneumatosis safely treated with repeat administration of Neostigmine. We recommend consideration of neostigmine in select cases for ACPO with pneumatosis with favorable indicators in the hopes of decreasing morbidity and mortality from invasive procedures.Figure: KUB showing pan-dilated colon.Figure: CT Scan showing pneumatosis in the right colon and cecum.

Xylanase, protease and superdosing phytase interactions in broiler performance, carcass yield and digesta transit time.

The interaction of xylanase, protease and superdosing (1,500 FTU/kg) phytase in a 2 × 2 × 2 factorial arrangement was studied in broilers fed sorghum-based diets. A total of 2,800 one-day-old unsexed Ross 308 chicks were housed in 56 pens with 50 birds per pen, with or without inclusion of xylanase, protease and phytase, totaling 8 treatments and 7 replicates per treatment. Body weight (BW) and feed intake (FI) were measured at 21 and 42 days of age, and mortality corrected feed conversion ratio (FCR) was calculated for each period and cumulatively. Tibia ash and carcass yield were determined in 2 birds per replicate at 21 and 42 days of age, respectively. Digesta transit time was determined at 21, 28, 35 and 42 days of age using 5 birds per replicate. Results showed that superdosing phytase increased BW and FI at 42 days of age (P < 0.05) and xylanase improved FCR (P < 0.05). Xylanase and phytase also positively influenced carcass yield and breast weight, respectively. Overall, inclusion of superdosing phytase increased transit time when included in a diet containing xylanase, and no change with protease inclusion. In conclusion, the beneficial effects of xylanase, protease and superdosing phytase in broiler performance were not additive. This limitation is likely not related to the lack of efficacy of any one of the individual enzymes but to a limitation of the bird to respond additively to successive additions of enzymes.

Colonic Transit Time Is a Driven Force of the Gut Microbiota Composition and Metabolism: In Vitro Evidence.

Background/AimsHuman gut microbiota harbors numerous metabolic properties essential for the host’s health. Increased intestinal transit time affects a part of the population and is notably observed with human aging, which also corresponds to modifications of the gut microbiota. Thus we tested the metabolic and compositional changes of a human gut microbiota induced by an increased transit time simulated in vitro.MethodsThe in vitro system, Environmental Control System for Intestinal Microbiota, was used to simulate the environmental conditions of 3 different anatomical parts of the human colon in a continuous process. The retention times of the chemostat conditions were established to correspond to a typical transit time of 48 hours next increased to 96 hours. The bacterial communities, short chain fatty acids and metabolite fingerprints were determined.ResultsIncrease of transit time resulted in a decrease of biomass and of diversity in the more distal compartments. Short chain fatty acid analyses and metabolite fingerprinting revealed increased activity corresponding to carbohydrate fermentation in the proximal compartments while protein fermentations were increased in the lower parts.ConclusionsThis study provides the evidence that the increase of transit time, independently of other factors, affects the composition and metabolism of the gut microbiota. The transit time is one of the factors that explain some of the modifications seen in the gut microbiota of the elderly, as well as patients with slow transit time.

Abstract B35: Enhanced antitumor efficacy by combining oncolytic herpes simplex virus and Aurora A kinase inhibition in models of neuroblastoma and malignant peripheral nerve sheath tumor

Abstract We previously reported xenograft models of neuroblastoma and malignant peripheral nerve sheath tumor (MPNST) are responsive to direct intratumoral injection of oncolytic Herpes Simplex Viruses (Parikh et al., Ped Blood Can 44:469, 2005; Mahller et al., Ped Blood Can 46:745, 2006; Mahller et al., Can Res 68:1170, 2008). We have confirmed these findings using an oncolytic HSV, Seprehvir (HSV1716), which is in clinical trials that include pediatric patients (NCT00931931, NCT02031965). The models showed wide variability, however, with some models having maintained complete responses and others showing only delayed growth. Because DNA viruses are highly dependent on normal nuclear machinery for DNA synthesis/replication and virus packaging/assembly, we postulated that increased transit time in mitosis may be beneficial to an oncolytic DNA virus. Aurora A Kinase is an enzyme critical for formation of centrioles and mitotic spindles during mitosis and is often dysregulated in cancer. The selective AAK inhibitor, Alisertib (MLN8237), arrests cells in G2/M and has significant activity in models of neuroblastoma (data from the Pediatric Preclinical Testing Program) and in MPNST (data from our prior study: Patel et al., Clin Can Res 18:5020, 2012). We found tumor responses in xenograft models using the combination of Seprehvir and Alisertib was more than additive. Immunohistochemical staining for HSV antigens revealed a marked difference in the extent and spread of virus as early as 24 hrs after virus injection. Our preliminary data assessing kinetics of virus infection suggest that Alisertib pretreatment enhances virus uptake and spread, accounting for the combinatorial effects. These data strongly suggest alisertib pretreatment “primes” tumor cells, making them highly susceptible to virus infection and spread and greatly accelerates the virolytic effects. Overall, our findings support clinical testing of Alisertib combined with Seprehvir in patients with refractory neurogenic tumors such as neuroblastoma and MPNST. Citation Format: Mark Currier, Tilat Rizvi, Brooke Nartker, Duo Chen, Chun-Yu Chen, Pin-Yi Wang, Les Sprague, Meghan Franczek, Ami Patel, Katherine Chaney, Keri Streby, Jeff Ecsedy, Joe Conner, Nancy Ratner, Timothy Cripe. Enhanced antitumor efficacy by combining oncolytic herpes simplex virus and Aurora A kinase inhibition in models of neuroblastoma and malignant peripheral nerve sheath tumor. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr B35.

Commonly Used Clinical Intravenous Fluid Formulations Differentially Affect Sickle Red Blood Cell Stiffness and Transit Time

Background:Disruption of red blood cell (RBC) volume regulation and water homeostasis is a major component of sickle cell pathophysiology. As such, hydration is a mainstay of prevention and treatment of vaso-occlusive crises (VOC) in patients with sickle cell disease (SCD). However, evidence for guiding clinicians' choice for intravenous (IV) fluid hydration in the acute setting is lacking (Okomo, Coch Data Syst Rev, 2012). Pediatric hematologists typically discourage rapid infusion of hypotonic fluid given the risk of hyponatremia, although such fluids as 5% dextrose with 34meq/L or 77meq/L sodium are often used after stabilizing various acute clinical situations relevant to SCD. Although altered sodium concentration and osmolarity have been shown to affect erythrocyte swelling and rheology, dextrose-containing fluids used clinically such as D5 ¼ and D5 ½ normal saline (NS), have not been studied (Reinhart et al., Mic Res, 2015; Hijiya et al., J Lab Clin Med, 1991). To those ends, we sought to investigate the effect of different clinically relevant IV fluid formulations on normal and sickle RBC stiffness and deformability.Methods:Fresh blood was obtained from healthy volunteers and patients with sickle cell anemia (SS) on hydroxyurea and not transfused for at least 100 days. Sterile, clinical grade fluids stored at room temperature were used for the experiments (Baxter, Figure 1A). Our laboratory has previously published a description of a microfluidic device comprised of multiple parallel microchannels 5μm wide recapitulating the in vivo geometry of capillaries (Rosenbluth et al., Lab Chip, 2008). This microvasculature-on-a-chip enables measurements of single-RBC transit times, which correlate with cell stiffness (Figure 1B,C). For the transit time experiments, a master silicon wafer was used to mold the microfluidic channels out of polydimethylsiloxane (PDMS) silicone. Centrifuged RBCs were washed with phosphate-buffered saline (PBS) and then diluted to 0.5% hematocrit (HCT) in the various fluids prior to flow. Cell suspensions were perfused into a microfluidic device pre-coated with 2% bovine serum albumin (BSA) at an average linear flow rate of 0.50 mm s-1 in the smallest channels with a syringe pump (Harvard Apparatus) and then imaged at 20x at 20 frames per second. Images were recorded for future analysis. For the experiments assessing RBC shape, washed RBCs were diluted with PBS to 0.5% HCT and imaged at 40x in plastic wells at time 0. PBS was removed and 100 μL of each clinical fluid formulation was added to the wells and images were then obtained over time. RBC circularity was calculated using custom-written scripts in Matlab (Figure 1D).Results:RBC transit times in both healthy and sickle blood were affected by osmolarity and the various solute concentrations (Figures 2A,B). Transit times of sickle RBCs in all IV fluid formulations were significantly higher, over 10 times, than that of RBCs from healthy donors. Transit times for both healthy and sickle donors were least in the D5 ¼ NS solution. Of note, sickle RBC transit time was greatest in the NS solution. Sickle RBC circularity also changed with solute concentration and osmolarity with statistical significance (Figure 2C). Cells with the highest change in circularity from baseline were also those exposed to the D5 ¼ NS solution.Conclusion:Our results suggest the stiffness of sickle RBCs is affected by different formulations of clinical IV fluids. Increased transit time of sickle RBCs in NS through our device may in part be explained by the decreased circularity, indicating that RBCs adopt more irregular shapes in this fluid. This, in turn, could lead to increased propensity of microchannel obstruction. Although the exact mechanisms are unclear, this begs the question of whether NS is an appropriate choice for initial fluid resuscitation for VOC and other SCD-related complications as it could exacerbate the already high stiffness and shape irregularity of sickle RBCs, further increasing microvascular occlusion. As these in vitro results have significant clinical implications, ongoing experiments involve investigating how these fluid-dependent effects may alter sickle RBC adhesion in 'endothelialized' microfluidic devices, how different oxygen tensions affect these fluid-mediated effects, potential differences on and off of hydroxyurea, and the underlying mechanisms of this IV fluid formulation-dependent effect. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.