Small intestinal length: a factor essential for gut adaptation

Radial WNT5A-Guided Post-mitotic Filopodial Pathfinding Is Critical for Midgut Tube Elongation

The early midgut undergoes intensive elongation, but the underlying cellular and molecular mechanisms are unknown. The early midgut epithelium is pseudostratified, and its nuclei travel between apical and basal surfaces in concert with cell cycle. Using 3D confocal imaging and 2D live imaging, we profiled behaviors of individual dividing cells. As nuclei migrate apically for mitosis, cells maintain a basal process (BP), which splits but is inherited by only one daughter. After mitosis, some daughters directly use the inherited BP as a "conduit" to transport the nucleus basally, while >50% of daughters generate a new basal filopodium and use it as a path to return the nucleus. Post-mitotic filopodial "pathfinding" is guided by mesenchymal WNT5A. Without WNT5A, some cells fail to tether basally and undergo apoptosis, leading to a shortened midgut. Thus, these studies reveal previously unrecognized strategies for efficient post-mitotic nuclear trafficking, which is critical for early midgut elongation.

Etiology and prognosis of pediatric short bowel syndrome

Pediatric intestinal failure is a complex and devastating condition defined as the inability of the intestine to absorb an adequate amount of fluid and nutrients to sustain life. The primary goal of intestinal failure treatment is to achieve enteral autonomy with a customized treatment plan. Although recent improvements in intestinal failure patient care have led to significant improvements in the morbidity and mortality rate, children with intestinal failure are at risk for multiple complications such as intestinal failure associated liver disease, recurrent septic episodes, central line complications, metabolic bone disease, impaired kidney function, and failure to thrive. In this article, we review the current literature on the etiology and factors affecting prognosis of pediatric IF.

Biopharmaceutical considerations in paediatrics with a view to the evaluation of orally administered drug products - a PEARRL review

OBJECTIVES

In this review, the current biopharmaceutical approaches for evaluation of oral formulation performance in paediatrics are discussed.

KEY FINDINGS

The paediatric gastrointestinal (GI) tract undergoes numerous morphological and physiological changes throughout its development and growth. Some physiological parameters are yet to be investigated, limiting the use of the existing in vitro biopharmaceutical tools to predict the in vivo performance of paediatric formulations. Meals and frequencies of their administration evolve during childhood and affect oral drug absorption. Furthermore, the establishment of a paediatric Biopharmaceutics Classification System (pBCS), based on the adult Biopharmaceutics Classification System (BCS), requires criteria adjustments. The usefulness of computational simulation and modeling for extrapolation of adult data to paediatrics has been confirmed as a tool for predicting drug formulation performance. Despite the great number of successful physiologically based pharmacokinetic models to simulate drug disposition, the simulation of drug absorption from the GI tract is a complicating issue in paediatric populations.

SUMMARY

The biopharmaceutics tools for investigation of oral drug absorption in paediatrics need further development, refinement and validation. A combination of in vitro and in silico methods could compensate for the uncertainties accompanying each method on its own.

EB 2017 Article: Interpretation of the lactulose:mannitol test in rural Malawian children at risk for perturbations in intestinal permeability

The dual sugar absorption test, specifically the lactulose:mannitol test, is used to assess gut health. Lactulose absorption is said to represent gut damage and mannitol absorption is used as a measure of normal small bowel function and serves as normalizing factor for lactulose. A underappreciated limitation of this common understanding of the lactulose:mannitol test is that mannitol is not absorbed to any substantial extent by a transcellular process. Additionally, this interpretation of lactulose:mannitol is not consistent with current understanding of paracellular pathways, where three pathway types exist: pore, leak, and unrestricted. Pore and leak pathways are regulated biological constructions of the small bowel barrier, and unrestricted pathways represent micropathological damage. We analyzed 2334 lactulose:mannitol measurements rigorously collected from 622 young rural Malawian children at high risk for poor gut health in light of the pathway model. An alternative method of normalizing for gut length utilizing autopsy data is described. In our population, absorbed lactulose and mannitol are strongly correlated, r = 0.68 P <0.0001, suggesting lactulose and mannitol are traversing the gut barrier via the same pathways. Considering measurements where pore pathways predominate, mannitol flux is about 14 times that of lactulose. As more leak pathways are present, this differential flux mannitol:lactulose falls to 8:1 and when increased numbers of unrestricted pathways are present, the differential flux of mannitol:lactulose is 6:1. There was no substantial correlation between the lactulose:mannitol and linear growth. Given that mannitol will always pass through a given pathway at a rate at least equal to that of lactulose, and lactulose absorption is a composite measure of flux through both physiologic and pathologic pathways, we question the utility of the lactulose:mannitol test. We suggest using lactulose alone is as informative as lactulose:mannitol in a sugar absorption testing in subclinical gut inflammation. Impact statement Our work integrates the standard interpretation of the lactulose:mannitol test (L:M), with mechanistic insight of intestinal permeability. There are three paracellular pathways in the gut epithelium; pore, leak, and unrestricted. Using thousands of L:M measurements from rural Malawian children at risk for increased intestinal permeability, we predict the differential flux of L and M through the pathways. Our findings challenge the traditional notions that little L is absorbed through a normal epithelial barrier and that M is a normalizing factor for L. Our observations are consistent with pore pathways allowing only M to pass. And that substantial amounts of L and M pass through leak pathways which are normal, regulated, cell-junctional adaptations. So M is a composite measure of all pathways, and L is not a measure solely of pathologic gut damage. Using L alone as a probe will yield more information about gut health than L:M.

Our Gut Microbiome: The Evolving Inner Self

The "holobiont" concept, defined as the collective contribution of the eukaryotic and prokaryotic counterparts to the multicellular organism, introduces a complex definition of individuality enabling a new comprehensive view of human evolution and personalized characteristics. Here, we provide snapshots of the evolving microbial-host associations and relations during distinct milestones across the lifespan of a human being. We discuss the current knowledge of biological symbiosis between the microbiome and its host and portray the challenges in understanding these interactions and their potential effects on human physiology, including microbiome-nervous system inter-relationship and its relevance to human variation and individuality.

In vitro dynamic model simulating the digestive tract of 6-month-old infants

Background

In vivo assays cannot always be conducted because of ethical reasons, technical constraints or costs, but a better understanding of the digestive process, especially in infants, could be of great help in preventing food-related pathologies and in developing new formulas with health benefits. In this context, in vitro dynamic systems to simulate human digestion and, in particular, infant digestion could become increasingly valuable.

Objective

To simulate the digestive process through the use of a dynamic model of the infant gastroenteric apparatus to study the digestibility of starch-based infant foods.

Design

Using M.I.D.A (Model of an Infant Digestive Apparatus), the oral, gastric and intestinal digestibility of two starch-based products were measured: 1) rice starch mixed with distilled water and treated using two different sterilization methods (the classical method with a holding temperature of 121°C for 37 min and the HTST method with a holding temperature of 137°C for 70 sec) and 2) a rice cream with (premium product) or without (basic product) an aliquot of rice flour fermented by Lactobacillus paracasei CBA L74. After the digestion the foods were analyzed for the starch concentration, the amount of D-glucose released and the percentage of hydrolyzed starch.

Results

An in vitro dynamic system, which was referred to as M.I.D.A., was obtained. Using this system, the starch digestion occurred only during the oral and intestinal phase, as expected. The D-glucose released during the intestinal phase was different between the classical and HTST methods (0.795 grams for the HTST versus 0.512 for the classical product). The same analysis was performed for the basic and premium products. In this case, the premium product had a significant difference in terms of the starch hydrolysis percentage during the entire process.

Conclusions

The M.I.D.A. system was able to digest simple starches and a more complex food in the correct compartments. In this study, better digestibility of the premium product was revealed.

Maintenance of Distal Intestinal Structure in the Face of Prolonged Fasting: A Comparative Examination of Species From Five Vertebrate Classes

It was recently shown that fasting alters the composition of microbial communities residing in the distal intestinal tract of animals representing five classes of vertebrates [i.e., fishes (tilapia), amphibians (toads), reptiles (leopard geckos), birds (quail), and mammals (mice)]. In this study, we tested the hypothesis that the extent of tissue reorganization in the fasted distal intestine was correlated with the observed changes in enteric microbial diversity. Segments of intestine adjacent to those used for the microbiota study were examined histologically to quantify cross-sectional and mucosal surface areas and thicknesses of mucosa, submucosa, and tunica muscularis. We found no fasting-induced differences in the morphology of distal intestines of the mice (3 days), quail (7 days), or geckos (28 days). The toads, which exhibited a general increase in phylogenetic diversity of their enteric microbiota with fasting, also exhibited reduced mucosal circumference at 14 and 21 days of fasting. Tilapia showed increased phylogenetic diversity of their enteric microbiota, and showed a thickened tunica muscularis at 21 days of fasting; but this morphological change was not related to microbial diversity or absorptive surface area, and thus, is unlikely to functionally match the changes in their microbiome. Given that fasting caused significant increases and reductions in the enteric microbial diversity of mice and quail, respectively, but no detectable changes in distal intestine morphology, we conclude that reorganization is not the primary factor shaping changes in microbial diversity within the fasted colon, and the observed modest structural changes are more related to the fasted state. Anat Rec, 300:2208-2219, 2017. © 2017 Wiley Periodicals, Inc.

Intestinal Rehabilitation Programs in the Management of Pediatric Intestinal Failure and Short Bowel Syndrome

Intestinal failure is a rare, debilitating condition that presents both acute and chronic medical management challenges. The condition is incompatible with life in the absence of the safe application of specialized and individualized medical therapy that includes surgery, medical equipment, nutritional products, and standard nursing care. Intestinal rehabilitation programs are best suited to provide such complex care with the goal of achieving enteral autonomy and oral feeding with or without intestinal transplantation. These programs almost all include pediatric surgeons, pediatric gastroenterologists, specialized nurses, and dietitians; many also include a variety of other medical and allied medical specialists. Intestinal rehabilitation programs provide integrated interdisciplinary care, more discussion of patient management by involved specialists, continuity of care through various treatment interventions, close follow-up of outpatients, improved patient and family education, earlier treatment of complications, and learning from the accumulated patient databases. Quality assurance and research collaboration among centers are also goals of many of these programs. The combined and coordinated talents and skills of multiple types of health care practitioners have the potential to ameliorate the impact of intestinal failure and improve health outcomes and quality of life.

Guidance on the risk assessment of substances present in food intended for infants below 16 weeks of age

Following a request from the European Commission to EFSA, the EFSA Scientific Committee (SC) prepared a guidance for the risk assessment of substances present in food intended for infants below 16 weeks of age. In its approach to develop this guidance, the EFSA SC took into account, among others, (i) an exposure assessment based on infant formula as the only source of nutrition; (ii) knowledge of organ development in human infants, including the development of the gut, metabolic and excretory capacities, the brain and brain barriers, the immune system, the endocrine and reproductive systems; (iii) the overall toxicological profile of the substance identified through the standard toxicological tests, including critical effects; (iv) the relevance for the human infant of the neonatal experimental animal models used. The EFSA SC notes that during the period from birth up to 16 weeks, infants are expected to be exclusively fed on breast milk and/or infant formula. The EFSA SC views this period as the time where health-based guidance values for the general population do not apply without further considerations. High infant formula consumption per body weight is derived from 95th percentile consumption. The first weeks of life is the time of the highest relative consumption on a body weight basis. Therefore, when performing an exposure assessment, the EFSA SC proposes to use the high consumption value of 260 mL/kg bw per day. A decision tree approach is proposed that enables a risk assessment of substances present in food intended for infants below 16 weeks of age. The additional information needed when testing substances present in food for infants below 16 weeks of age and the approach to be taken for the risk assessment are on a case-by-case basis, depending on whether the substance is added intentionally to food and is systemically available.

Exploring the Small Bowel: Update on Deep Enteroscopy

Deep enteroscopy allows for the diagnosis and treatment of small bowel disorders that historically required operative intervention. There are a variety of endoscopic platforms using balloons and rotational overtubes to facilitate small bowel intubation and even allow for total enteroscopy. Obscure gastrointestinal bleeding is the most common indication for deep enteroscopy. By visualizing segments of the small bowel not possible through standard EGD or push enteroscopy, deep enteroscopy has an established high rate of identification and treatment of bleeding sources. In addition to obscure bleeding, other common indications include diagnosis and staging of Crohn's disease, evaluation of findings on capsule endoscopy and investigation of possible small bowel tumors. Large endoscopy databases have shown deep enteroscopy to be not only effective but safe. Recent research has focused on comparing the diagnostic rates, efficacy, and total enteroscopy rates of the different endoscopic platforms.

Improved enteral tolerance following step procedure: systematic literature review and meta-analysis

Surgical management of children with short bowel syndrome (SBS) changed with the introduction of the serial transverse enteroplasty procedure (STEP). We conducted a systematic review and meta-analysis using MEDLINE and SCOPUS to determine if children with SBS had improved enteral tolerance following STEP. Studies were included if information about a child's pre- and post-STEP enteral tolerance was provided. A random effects meta-analysis provided a summary estimate of the proportion of children with enteral tolerance increase following STEP. From 766 abstracts, seven case series involving 86 children were included. Mean percent tolerance of enteral nutrition improved from 35.1 to 69.5. Sixteen children had no enteral improvement following STEP. A summary estimate showed that 87 % (95 % CI 77-95 %) of children who underwent STEP had an increase in enteral tolerance. Compilation of the literature supports the belief that SBS subjects' enteral tolerance improves following STEP. Enteral nutritional tolerance is a measure of efficacy of STEP and should be presented as a primary or secondary outcome. By standardizing data collection on children undergoing STEP procedure, better determination of nutritional benefit from STEP can be ascertained.

Generation of intestinal surface: an absorbing tale

The vertebrate small intestine requires an enormous surface area to effectively absorb nutrients from food. Morphological adaptations required to establish this extensive surface include generation of an extremely long tube and convolution of the absorptive surface of the tube into villi and microvilli. In this Review, we discuss recent findings regarding the morphogenetic and molecular processes required for intestinal tube elongation and surface convolution, examine shared and unique aspects of these processes in different species, relate these processes to known human maladies that compromise absorptive function and highlight important questions for future research.

Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2

The objective of the present study was to investigate the intestinal development of newborn intrauterine growth-restricted (IUGR) piglets subjected to normal nutrient intake (NNI) or restricted nutrient intake (RNI). Newborn normal birth weight (NBW) and IUGR piglets were allotted to NNI or RNI levels for 4 weeks from day 8 postnatal. IUGR piglets receiving NNI had similar growth performance compared with that of NBW piglets. Small intestine length and villous height were greater in IUGR piglets fed the NNI than that of piglets fed the RNI. Lactase activity was increased in piglets fed the NNI compared with piglets fed the RNI. Absorptive function, represented by active glucose transport by the Ussing chamber method and messenger RNA (mRNA) expressions of two main intestinal glucose transporters, Na+-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), were greater in IUGR piglets fed the NNI compared with piglets fed the RNI regimen. The apoptotic process, characterized by caspase-3 activity (a sign of activated apoptotic cells) and mRNA expressions of p53 (pro-apoptotic), bcl-2-like protein 4 (Bax) (pro-apoptotic) and B-cell lymphoma-2 (Bcl-2) (anti-apoptotic), were improved in IUGR piglets fed the NNI regimen. To test the hypothesis that improvements in intestinal development of IUGR piglets fed NNI might be mediated through circulating glucagon-like peptide-2 (GLP-2), GLP-2 was injected subcutaneously to IUGR piglets fed the RNI from day 8 to day 15 postnatal. Although the intestinal development of IUGR piglets fed the RNI regimen was suppressed compared with those fed the NNI regimen, an exogenous injection of GLP-2 was able to bring intestinal development to similar levels as NNI-fed IUGR piglets. Collectively, our results demonstrate that IUGR neonates that have NNI levels could improve intestinal function via the regulation of GLP-2.

In vitro biorelevant models for evaluating modified release mesalamine products to forecast the effect of formulation and meal intake on drug release

AIMS

Postprandial administration of solid oral dosage forms greatly changes the dissolution environment compared to fasted state administration. The aims of this study were to investigate and forecast the effect of co-administration of a meal on drug release for delayed and/or extended release mesalamine formulations as well as design of in vitro tests to distinguish among formulations in a biorelevant way.

METHODS

Five different mesalamine formulations (Asacol® 400 mg, Mezavant® 1200 mg, Pentasa® 500 mg and Salofalk® in the 250 mg and 500 mg strengths) were investigated with biorelevant dissolution methods using the USP apparatus III and USP apparatus IV (open loop mode) under both fasted and fed state conditions, as well as with the dissolution methods described in pharmacopeia for delayed and extended release mesalamine products.

RESULTS

Using the biorelevant experimental conditions proposed in this study, changes in release in the proximal gut due to meal intake are forecast to be minimal for Asacol®, Mezavant®, Pentasa® and Salofalk® 500 mg, while for Salofalk® 250 mg release was predicted to occur much earlier under fed state conditions. The USP apparatus III generally tended to result in faster dissolution rates and forecast more pronounced food effects for Salofalk® 250 mg than the USP apparatus IV. The biorelevant dissolution gradients were also able to reflect the in vivo behavior of the formulations.

CONCLUSIONS

In vitro biorelevant models can be useful in the comparison of the release behavior from different delayed and extended release mesalamine formulations as well as forecasting effects of concomitant meal intake on drug release.

The Surgical Approach to Short Bowel Syndrome - Autologous Reconstruction versus Transplantation

BACKGROUND

Short bowel syndrome (SBS) is a state of malabsorption resulting from massive small bowel resection leading to parenteral nutrition (PN) dependency. Considerable advances have been achieved in the medical and surgical management of SBS over the last few decades.

METHODS

This review discusses in detail the surgical approach to SBS.

RESULTS

Widespread use of PN enables long-term survival in patients with intestinal failure but at the cost of PN-associated life-threatening complications including catheter-associated blood stream infection, venous thrombosis, and liver disease. The goal of management of intestinal failure due to SBS is to enable enteral autonomy and wean PN by means of a multi-disciplinary approach. Availability of modified enteral feeding formulas have simplified nutrition supplementation in SBS patients. Similarly, advances in the medical field have made medications like growth hormone and glucagon-like peptide (GLP2) available to improve water and nutrient absorption as well as to enable achieving enteral autonomy. Autologous gastrointestinal reconstruction (AGIR) includes various techniques which manipulate the bowel surgically to facilitate the bowel adaptation process and restoration of enteral nutrition. Ultimately, intestinal transplantation can serve as the last option for the cure of intestinal failure when selectively applied.

CONCLUSION

SBS continues to be a challenging medical problem. Best patient outcomes can be achieved through an individualized plan, using various AGIR techniques to complement each other, and intestinal transplantation as a last resort for cure. Maximum benefit and improved outcomes can be achieved by caring for SBS patients at highly specialized intestinal rehabilitation centers.

Zinc Absorption Is Not Related to Dietary Phytate Intake in Infants and Young Children Based on Modeling Combined Data from Multiple Studies

BACKGROUND

It is widely understood that the 2 primary factors affecting dietary zinc absorption in adults are the quantities of zinc and phytate in the diet. Although a similar association of absorption to dietary zinc and phytate is presumed to exist in children, to our knowledge, no large-scale examination of the relation of zinc absorption to dietary and growth factors has been conducted.

OBJECTIVE

The goal was to apply an adult absorption model and related models to data from zinc absorption studies of infants and children in order to determine the nature of the relation of zinc absorption to dietary zinc and phytate, age, body size, and zinc homeostatic variables.

METHODS

Data from 236 children between 8 and 50 mo of age were obtained from stable-isotope studies of zinc absorption. Statistical and mechanistic models were fit to the data using linear and nonlinear regression analysis.

RESULTS

The effect of dietary phytate on zinc absorption when controlling for dietary zinc was very small and not statistically discernable (P = 0.29). A 500-mg/d increase in dietary phytate reduced absorbed zinc by <0.04 mg/d. Absorption was observed to vary with age, weight, and height (P < 0.0001) when controlling for dietary zinc. For example, absorption from 6 mg/d of dietary zinc increased by as much as 0.2 mg/d with a 12-mo increase in age. Absorption varied with weight and exchangeable zinc pool size (0.01 < P < 0.05) when controlling for dietary zinc and age.

CONCLUSIONS

The absence of a detectable phytate effect on zinc absorption raises caution about use of dietary phytate:zinc molar ratios to predict zinc bioavailability and does not support phytate reduction as a strategy to improve zinc status of young children. The effect of age on zinc absorption and the absence of a phytate effect should facilitate estimations of dietary zinc needs in young children.

The Fecal Microbiome in Pediatric Patients With Short Bowel Syndrome

BACKGROUND

Changes in the intestinal microbiome of patients with short bowel syndrome (SBS) are thought to significantly affect clinical outcome. These changes may not only delay enteral diet advancement but may also predispose patients to bacterial translocation, bacteremia, and liver disease. Patients with SBS are thought to be more susceptible to changes in gut microbial communities due to intestinal dysmotility and/or lack of anatomic safeguards such as the ileocecal valve.

MATERIALS AND METHODS

We analyzed the bacterial composition of 21 fecal specimens from 9 children with SBS and 8 healthy children ages 4 months to 8 years by 16S ribosomal RNA gene sequencing. The sequences were quality filtered and analyzed using QIIME, the Ribosomal Database Project Classifier, and the randomForest supervised learning algorithm.

RESULTS

The fecal microbiome of patients with SBS is different from that of healthy controls. Stool from patients with SBS had a significantly greater abundance of the bacterial classes Gammaproteobacteria and Bacilli. Stool from patients with SBS who experienced increased stool frequency tended to have increased abundance of Lactobacillus (P = .057) and decreased abundance of Ruminococcus.

CONCLUSION

This study shows that the fecal microbiome of patients with SBS is significantly different from that of healthy controls when analyzed by 16S metagenomics. Differences in the composition and function of gut microbiomes in children with SBS may affect bowel physiology, and these findings may provide new opportunities for intestinal rehabilitation and clinical management.

Risk assessment for extending the Biopharmaceutics Classification System-based biowaiver of immediate release dosage forms of fluconazole in adults to the paediatric population

OBJECTIVES

The paediatric population undergoes developmental changes in gastric pH, gastric emptying, intestinal transit time, membrane permeability, protein binding, body water, distribution and metabolism. It is widely recognised that changes in these parameters may result in an alteration of the plasma profile and thus in key bioequivalence parameters such as Cmax (maximum plasma concentration of drug) and area under the plasma concentration vs time profile curve. The aim of this work is to assess the risk of extending the biowaiver for immediate release dosage formulations of fluconazole from the adult to the paediatric population.

METHODS AND KEY FINDINGS

Fluconazole exhibits good solubility and very rapid dissolution characteristics in various pH media. The absorption of fluconazole in children is known to be complete (over 90%) and not impaired by elevated pH, which is prevalent during the early days of life. Dose numbers calculated using body surface area are less than 1. Therefore, the risk to drug absorption due to differences in gastric pH, gastric emptying, intestinal transit, membrane permeability and metabolising enzymes between adults and children is considered low.

CONCLUSIONS

Thus, it can be safely concluded that fluconazole meets highly soluble and highly permeable criteria in the paediatric population and can be allocated to class 1 of the Biopharmaceutics Classification System (BCS) for this population as well as in adults. Additionally, fluconazole has an excellent safety profile in children, similar to that in adults. The BCS-based biowaiver claimed in adults can be safely extended to the paediatric population provided that the requirements in excipient selection and dissolution profile comparison using BCS-based dissolution conditions as stated in the biowaiver monograph for fluconazole immediate release dosage forms in adults are fulfilled.

Intestinal failure-associated liver disease: a position paper of the ESPGHAN Working Group of Intestinal Failure and Intestinal Transplantation

Intestinal failure-associated liver disease is the most prevalent complication affecting children with intestinal failure receiving long-term parenteral nutrition. This paper reviews the definition, diagnostic criteria, pathogenesis, and risk factors. The authors discuss the role of enteral nutrition, parenteral nutrition, and its components, especially lipid emulsions. The authors also discuss the surgical treatment, including intestinal transplantation, its indications, technique, and results, and emphasise the importance of specialised intestinal failure centres.

Variation in small bowel length: factor in achieving total enteroscopy?

BACKGROUND AND AIM

Estimation of small bowel length is of interest following the recent development of device-assisted enteroscopy. This new technology allows access to the deep small bowel, but rates of examination of the entire small bowel (total enteroscopy) differ between study populations. Variation in small bowel length could factor into this observed irregularity in total enteroscopy rates. Medical literature contains limited information regarding small bowel length in living patients and conflicting data regarding small bowel length and its relationship to height and weight. We carried out small bowel measurements on surgical patients to further define the total length of the small bowel and its relationship to height, weight and body mass index (BMI).

METHODS

Measurement of ileojejunal length on 91 surgical patients undergoing laparotomy for routine indications. Demographic data were collected for each subject, including height, weight and BMI.

RESULTS

Small bowel length was found to vary widely between individuals (average 998.52 cm, range 630-1510 cm). Linear regression analysis demonstrated a statistically significant relationship between small bowel length and height (regression coefficient = 0.0561, P-value = 0.0238). A linear relationship between small bowel length and weight or BMI was not observed.

CONCLUSIONS

Length of the small bowel in humans is pertinent to advances in deep enteroscopy and existing surgical applications such as intestinal bypass and prevention of short gut syndrome. If average small bowel length varies with height, total enteroscopy may be easier to achieve in patients who are short in stature.

Emerging Piglet Models of Neonatal Short Bowel Syndrome

Short bowel syndrome (SBS) is a growing problem in the human neonatal population. In infants, SBS is the leading cause of intestinal failure, the state of being unable to absorb sufficient nutrients for growth and development. Neonates with SBS are dependent on long-term parenteral nutrition therapy, but many succumb to the complications of sepsis and liver disease. Research in neonatal SBS is challenged by the ethical limits of studying sick human neonates and the heterogeneous nature of the disease process. Outcomes in SBS vary depending on residual intestinal anatomy, intestinal length, patient age, and exposure to nutrition therapies. The neonatal piglet serves as an appropriate translational model of the human neonate because of similarities in gastrointestinal ontogeny, physiological maturity, and adaptive processes. Re-creating the disease process in a piglet model presents a unique opportunity for researchers to discover novel insights and therapies in SBS. Emerging piglet models of neonatal SBS now represent the entire spectrum of disease seen in human infants. This review aims to contextualize these emerging piglet models within the context of SBS as a heterogeneous disease. We first explore the factors that account for SBS heterogeneity and then explore the suitability of the neonatal piglet as an appropriate translational animal model. We then examine differences between the emerging piglet models of neonatal SBS and how these differences affect their translational potential to human neonates with SBS.

Exogenous glucagon-like peptide-2 improves outcomes of intestinal adaptation in a distal-intestinal resection neonatal piglet model of short bowel syndrome

BACKGROUND

Endogenous glucagon-like peptide-2 (GLP-2) levels and intestinal adaptation are reduced in distal-intestinal resection animal models of short bowel syndrome (SBS) that lack remnant ileum. We hypothesized that exogenous GLP-2 would improve intestinal adaptation in a distal-intestinal resection neonatal piglet model of SBS.

METHODS

In all, 35 piglets were randomized to 2 treatment and 3 surgical groups: control (sham), 75% mid-intestinal resection (JI), and 75% distal-intestinal resection (JC). Parenteral nutrition (PN) commenced on day 1 and was weaned as enteral nutrition (EN) advanced. IV GLP-2 (11 nmol/kg/d) or saline was initiated on day 2. Piglets were maintained for 14 d. Clinical, functional, morphological, and histological outcomes were obtained.

RESULTS

JC-GLP-2 piglets had fewer days on PN (10.0 ± 0.6 vs. 13.8 ± 0.2), more days on EN (4.0 ± 0.6 vs. 0.2 ± 0.2), a higher percentage of EN at termination (92 ± 5 vs. 52 ± 10%), fewer days of diarrhea (8.0 ± 0.7 vs. 12.3 ± 0.4), increased intestinal length (19 ± 4 vs. -5 ± 3%), and deeper jejunal crypts (248 ± 21 vs. 172 ± 12 μm), compared with saline piglets.

CONCLUSION

GLP-2 therapy improves clinical, morphological, and histological outcomes of intestinal adaptation in a distal-intestinal resection model of SBS. Since this anatomical subtype represents the majority of clinical cases of neonatal SBS, these results support a potential role for GLP-2 therapy in pediatric SBS.

ESPEN endorsed recommendations. Definition and classification of intestinal failure in adults

BACKGROUND & AIMS

Intestinal failure (IF) is not included in the list of PubMed Mesh terms, as failure is the term describing a state of non functioning of other organs, and as such is not well recognized. No scientific society has yet devised a formal definition and classification of IF. The European Society for Clinical Nutrition and Metabolism guideline committee endorsed its "home artificial nutrition and chronic IF" and "acute IF" special interest groups to write recommendations on these issues.

METHODS

After a Medline Search, in December 2013, for "intestinal failure" and "review"[Publication Type], the project was developed using the Delphi round methodology. The final consensus was reached on March 2014, after 5 Delphi rounds and two live meetings.

RESULTS

The recommendations comprise the definition of IF, a functional and a pathophysiological classification for both acute and chronic IF and a clinical classification of chronic IF. IF was defined as "the reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth".

CONCLUSIONS

This formal definition and classification of IF, will facilitate communication and cooperation among professionals in clinical practice, organization and management, and research.

Randomized controlled trial of early enteral fat supplement and fish oil to promote intestinal adaptation in premature infants with an enterostomy

OBJECTIVE

To test the hypothesis that early enteral supplementing fat and fish oil decreases the duration of parenteral nutrition (PN) and increases enteral nutrition (EN) before bowel reanastomosis in premature infants with an enterostomy.

STUDY DESIGN

Premature infants (<2 months old) who had an enterostomy and tolerated enteral feeding at 20 mL/kg/day were randomized to usual care (control=18) or early supplementing enteral fat supplement and fish oil (treatment=18). Intravenous lipid was decreased as enteral fat intake was increased. Daily weight, clinical and nutrition data, and weekly length and head circumference were recorded. The primary outcomes were the duration of PN and volume of EN intake, and the secondary outcomes were weight gain (g/day), ostomy output (mL/kg/d), and serum conjugated bilirubin level (mg/dL) from initiating feeding to reanastomosis. Data were analyzed by Student t test or Wilcoxon rank sum test.

RESULTS

There were no differences in the duration of PN, ostomy output, and weight gain between the 2 groups before reanastomosis. However, supplemented infants received less intravenous lipid, had greater EN intake, and lower conjugated bilirubin before reanastomosis, and they also received greater total calorie, had fewer sepsis evaluations and less exposure to antibiotics and central venous catheters before reanastomosis, and had greater weight and length gain after reanastomosis (all P<.05).

CONCLUSION

Early enteral feeding of a fat supplement and fish oil was associated with decreased exposure to intravenous lipid, increased EN intake, and reduced conjugated bilirubin before reanastomosis and improved weight and length gain after reanastomosis in premature infants with an enterostomy.

Bioavailability of iron, zinc, and provitamin A carotenoids in biofortified staple crops

International research efforts, including those funded by HarvestPlus, a Challenge Program of the Consultative Group on International Agricultural Research (CGIAR), are focusing on conventional plant breeding to biofortify staple crops such as maize, rice, cassava, beans, wheat, sweet potatoes, and pearl millet to increase the concentrations of micronutrients that are commonly deficient in specific population groups of developing countries. The bioavailability of micronutrients in unfortified staple crops in developing regions is typically low, which raises questions about the efficacy of these crops to improve population micronutrient status. This review of recent studies of biofortified crops aims to assess the micronutrient bioavailability of biofortified staple crops in order to derive lessons that may help direct plant breeding and to infer the potential efficacy of food-based nutrition interventions. Although reducing the amounts of antinutrients and the conduction of food processing generally increases the bioavailability of micronutrients, antinutrients still possess important benefits, and food processing results in micronutrient loss. In general, biofortified foods with relatively higher micronutrient density have higher total absorption rates than nonbiofortified varieties. Thus, evidence supports the focus on efforts to breed plants with increased micronutrient concentrations in order to decrease the influence of inhibitors and to offset losses from processing.

Management of short bowel syndrome

Most intestinal failure in children is due to short bowel syndrome (SBS) where congenital or acquired lesions have led to an extensive loss of intestinal mass. The vast majority of morbidity and mortality of patients with SBS is due to complications secondary to their long term dependence on parenteral nutrition. In response to SBS, the intestine undergoes a process of remodeling termed adaptation. Principles guiding the medical management of SBS include providing adequate parenteral nutrition, fluids and electrolytes for growth and normal development, promoting small bowel adaptation, and preventing and treating complications related to the patient's underlying disease and their parenteral nutrition. Catheter associated blood stream infection (CABSI) is major source of morbidity and mortality in patients with intestinal failure from SBS. Intestinal failure associated liver disease (IFALD)is another major source of morbidity and mortality in patients with SBS. IFALD is the most consistent negative predictor of outcome including death and continued parenteral nutrition dependence. Enteral nutrition is critical for intestinal adaptation and preventing IFALD. Patients with SBS who develop dilated dysmotile segments may benefit from autologous intestinal reconstruction surgery (AIRS) with the goal of decreasing stasis and disordered motility through intestinal narrowing and lengthening. Patients with SBS should be referred for transplantation if they have failed intestinal rehabilitation including AIRS, have no reasonable chance for enteral feeding tolerance, develop irreversible IFALD, have recurrent sepsis, or have exhausted their central venous access sites. With improvements in medical and surgical care, overall survival of patients with SBS now exceeds 90%.

Safety and utility of capsule endoscopy for infants and young children

AIM: To assess the safety and utility of capsule endoscopy (CE) for children who are unable to swallow the capsule endoscope.

METHODS: The medical records of all of the children who underwent CE between 2010 and 2012 were retrospectively reviewed. The patients were divided into 2 groups: group A included patients who were unable to swallow the capsule endoscope, and group B included patients who were able to swallow it. For the patients who were unable to swallow the capsule endoscope, it was placed in the duodenum endoscopically. The small bowel transit time, endoscopic diagnosis and complications of the 2 groups were compared.

RESULTS: During the study period, 28 CE procedures were performed in 26 patients. Group A included 11 patients with a median age of 2 years (range 10 mo-9 years), and group B included 15 patients with a median age of 12 years (range 8 years-16 years). The lightest child in the study weighed 7.9 kg. The detection rates did not differ between the 2 groups. The median small bowel transit time was 401 min (range 264-734 min) in group A and 227 min (range 56-512 min) in group B (P = 0.0078). No serious complications, including capsule retention, occurred. No significant mucosal trauma occurred in the pharynx, esophagus, stomach or duodenum when the capsule was introduced using an endoscope.

CONCLUSION: CE is a safe and useful procedure for infants and young children who are unable to swallow the capsule endoscope.

Serum 7-alpha-hydroxy-4-cholesten-3-one as a marker for bile acid loss in children

OBJECTIVE

To establish age-related reference values for 7-alpha-hydroxy-4-cholesten-3-one (C4) in a pediatric population and to investigate bile acid malabsorption in children with short bowel syndrome (SBS).

STUDY DESIGN

Serum was obtained between 8:00 a.m. and 11:00 a.m. from 100 healthy children (52% males, 9 months to 18 years of age) after 10 hours of fasting. Pediatric patients with SBS served as disease controls (n = 12). Following solid-phase extraction and purification, C4 was determined by high-performance liquid chromatography using a ultraviolet detector at a wavelength of 241 nm. The upper limit of normal for C4 concentrations was defined as the mean plus 2 SD of the log-normal distribution.

RESULTS

The mean concentration and SD of C4 in healthy children was 22.8 ± 15.8 ng/mL with no relation to age or sex and an upper limit of normal of 66.5 ng/mL. Normal C4 values were found in 97 of 100 healthy children, and all 12 patients with SBS had C4 concentrations above 100 ng/mL (mean 299.6 ± 167.8 ng/mL; range 105.7-562.1 ng/mL, P < .0001 compared with controls).

CONCLUSIONS

The determined upper limit of normal for C4 concentration in healthy children corresponds to previously published levels in healthy adults and is independent of age and sex. The consistently elevated C4 concentrations in our patients with SBS confirm the reliability of this noninvasive, nonisotopic method to assess bile acid malabsorption in children.

Management of short bowel syndrome in infancy

Short bowel syndrome (SBS) is a reduction in functioning bowel length which is most often a result of surgical resection. Risk factors in the neonatal period include necrotising enterocolitis, small bowel atresia and gastroschisis. With increasing survival of preterm infants there is an increase in incidence. Management is dependent on the use of parenteral nutrition to maintain fluid and electrolyte homeostasis and promote growth and development with the longer term aim being to promote intestinal adaptation to achieve partial or complete enteral autonomy. In this review we discuss the incidence, aetiology, pathophysiology, medical and surgical treatments and outcome.

Early enteral fat supplement and fish oil increases fat absorption in the premature infant with an enterostomy

OBJECTIVE

To test the hypothesis that in the premature infant with an enterostomy, early enteral supplementation with Microlipid (fat supplement) and fish oil increases enteral fat absorption and decreases the requirement for Intralipid (intravenous fat emulsion).

STUDY DESIGN

Premature infants (<2 months old) with an enterostomy after surgical treatment for necrotizing enterocolitis or spontaneous intestinal perforation and tolerating enteral feeding at 20 mL/kg/day were randomized to usual care (control 18 infants) or early supplementing enteral fat and fish oil (treatment 18 infants). Intravenous fat emulsion was decreased as enteral fat intake was increased. Daily weight, ostomy output, and nutrition data were recorded. Weekly 24-hour ostomy effluent was collected until bowel reanastomosis, and fecal fat, fecal liquid, and dry feces were measured. Fat absorption (g/kg/d) was calculated by subtracting fecal fat from dietary fat. The fecal liquid and dry feces were reported as mg/g wet stool. Date were analyzed by using ANOVA and mixed-effects model.

RESULTS

The interval from initial postoperative feeding to bowel reanastomosis varied from 2 to 10 weeks. The treatment group received more dietary fat and less intravenous fat emulsion and had higher enteral fat absorption, less fecal liquid, and drier feces than the control group. These effects were greater among infants with a high ostomy compared with those with a low ostomy. Enteral fat intake was significantly correlated with fat absorption.

CONCLUSION

Early enteral fat supplement and fish oil increases fat absorption and decreases the requirement for intravenous fat emulsion. This approach could be used to promote bowel adaptation and reduce the use of intravenous fat emulsion in the premature infant with an enterostomy.

Introducing enteral feeds in the high-risk preterm infant

Establishing enteral feeding in high-risk, very preterm infants is difficult: they are born at a time of rapid growth and development, yet immaturity of gut and metabolic function makes it difficult to accumulate adequate nutrients. Parenteral nutrition will provide the bulk of nutrients in the first few weeks while the preterm infant gut adapts. Intestinal function, nutritional substrate and microbial environment all interact to enable this to happen, and imbalance of these components may result in the serious condition of necrotising enterocolitis. Mother's breast milk is the safest feed and there is no evidence that delaying the introduction of small volumes is of benefit. Volumes can gradually be increased as tolerated and nutrient intakes optimised with addition of supplements or breast-milk fortifier to minimise the extent of extrauterine growth restriction.

Delayed primary serial transverse enteroplasty as a novel management strategy for infants with congenital ultra-short bowel syndrome

BACKGROUND

Congenital ultra-short bowel syndrome (USBS) is a challenging problem with a poor outcome. We report a new management approach for USBS infants that attempts to optimize gut growth potential.

METHODS

We report five neonates with USBS in whom no correction was performed at primary surgery except placement of a gastrostomy (G) tube. Sham feeds were started with intermittent G-tube clamping to induce bowel dilatation/growth. Serial fluoroscopy was done until bowel caliber reached 5 cm. STEP was performed and continuity established to the colonic remnant. Small bowel length (SBL) and enteral caloric intake were tabulated.

RESULTS

Patients were born with a mean residual SBL of 19 ± 7.6 cm (14.8% of expected). Median duration of sham feeds prior to STEP was 108 (range 27-232)days. Mean SBL at STEP was 47 ± 12.1cm, which increased post-STEP to 70 ± 12.7 cm (a mean increase of 296% from birth, representing 36.4% ± 13.1% of expected gut length). With a median follow-up time of 20 months (range 8-28), 4/5 achieved >50% enteral calories and have normal liver function. One has undergone liver transplantation.

CONCLUSIONS

In USBS patients, delayed surgical correction with sham feeds accelerates gut growth, optimizing potential for autologous reconstruction. This approach may offer greater opportunity for intestinal adaptation than traditional options.

Diagnosis and management of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) can result from failure of the gastric acid barrier, failure of small intestinal motility, anatomic alterations, or impairment of systemic and local immunity. The current accepted criteria for the diagnosis of SIBO is the presence of coliform bacteria isolated from the proximal jejunum with >10(5) colony-forming units/mL. A major concern with luminal aspiration is that it is only one random sampling of the small intestine and may not always be representative of the underlying microbiota. A new approach to examine the underlying microbiota uses rapid molecular sequencing, but its clinical utilization is still under active investigation. Clinical manifestations of SIBO are variable and include bloating, flatulence, abdominal distention, abdominal pain, and diarrhea. Severe cases may present with nutrition deficiencies due to malabsorption of micro- and macronutrients. The current management strategies for SIBO center on identifying and correcting underlying causes, addressing nutrition deficiencies, and judicious utilization of antibiotics to treat symptomatic SIBO.

Congenital short bowel syndrome as the presenting symptom in male patients with FLNA mutations

PURPOSE

Autosomal recessive congenital short bowel syndrome is caused by mutations in CLMP. No mutations were found in the affected males of a family with presumed X-linked congenital short bowel syndrome or in an isolated male patient. Our aim was to identify the disease-causing mutation in these patients.

METHODS

We performed mutation analysis of the second exon of FLNA in the two surviving affected males of the presumed X-linked family and in the isolated patient.

RESULTS

We identified a novel 2-base-pair deletion in the second exon of FLNA in all these male patients. The deletion is located between two nearby methionines at the N-terminus of filamin A. Previous studies showed that translation of FLNA occurs from both methionines, resulting in two isoforms of the protein. We hypothesized that the longer isoform is no longer translated due to the mutation and that this mutation is therefore not lethal for males in utero.

CONCLUSION

Our findings emphasize that congenital short bowel syndrome can be the presenting symptom in male patients with mutations in FLNA.

Jun N-terminal kinase maintains tissue integrity during cell rearrangement in the gut

Tissue elongation is a fundamental morphogenetic process that generates the proper anatomical topology of the body plan and vital organs. In many elongating embryonic structures, tissue lengthening is driven by Rho family GTPase-mediated cell rearrangement. During this dynamic process, the mechanisms that modulate intercellular adhesion to allow individual cells to change position without compromising structural integrity are not well understood. In vertebrates, Jun N-terminal kinase (JNK) is also required for tissue elongation, but the precise cellular role of JNK in this context has remained elusive. Here, we show that JNK activity is indispensable for the rearrangement of endoderm cells that underlies the elongation of the Xenopus gut tube. Whereas Rho kinase is necessary to induce cell intercalation and remodel adhesive contacts, we have found that JNK is required to maintain cell-cell adhesion and establish parallel microtubule arrays; without JNK activity, the reorganizing endoderm dissociates. Depleting polymerized microtubules phenocopies this effect of JNK inhibition on endoderm morphogenesis, consistent with a model in which JNK regulates microtubule architecture to preserve adhesive contacts between rearranging gut cells. Thus, in contrast to Rho kinase, which generates actomyosin-based tension and cell movement, JNK signaling is required to establish microtubule stability and maintain tissue cohesion; both factors are required to achieve proper cell rearrangement and gut extension. This model of gut elongation has implications not only for the etiology of digestive tract defects, but sheds new light on the means by which intra- and intercellular forces are balanced to promote topological change, while preserving structural integrity, in numerous morphogenetic contexts.

What is the normal small bowel length in humans? first donor-based cohort analysis

Normal small bowel length (SBL) has been reported within a wide range, but never studied in a cohort of either pediatric or adult deceased donors. Between 5/2006 and 2/2011, SBL was measured in all grafts procured for intestinal transplantation at a single center and used for either isolated intestinal transplant (15) or multiorgan transplants (5) employing a standardized method. SBL was the only not significantly different variable among pediatric and adult donors divided by age 16. Furthermore, donors were classified in 3 groups: group 1: Height < 70 cm, group 2: 71-150 cm and group 3: ≥ 151 cm. Mean age was: 0.58, 5.6, 22.01 years, respectively. Mean height and weight were 65.8, 123.2, 166.1 cm (p = 0.001) and 6.9, 23.8, 65.2 kg (p = 0.001), for each group. The SBL by group was: 283.0, 324.7, 356.0 cm, remaining as the only nonsignificant variable (p = 0.06), in contrast to BMI, BSA (p = 0.001). The SBL/height ratio: 4.24, 2.7, 2.12 (p = 0.001; rho: -0.623) or SBL/BSA ratio was 8.36, 3.7, and 2.03, respectively (p : 0.0001; rho: -0.9). SBL does not increase with growth like other anthropometric variables. The SBL/height ratio significantly decreases with growth; however, bowel diameter increases, which needs further evaluation.

Summary of the National Institute of Child Health and Human Development-best pharmaceuticals for Children Act Pediatric Formulation Initiatives Workshop-Pediatric Biopharmaceutics Classification System Working Group

BACKGROUND

The Biopharmaceutics Classification System (BCS) allows compounds to be classified based on their in vitro solubility and intestinal permeability. The BCS has found widespread use in the pharmaceutical community to be an enabling guide for the rational selection of compounds, formulation for clinical advancement, and generic biowaivers. The Pediatric Biopharmaceutics Classification System (PBCS) Working Group was convened to consider the possibility of developing an analogous pediatric-based classification system. Because there are distinct developmental differences that can alter intestinal contents, volumes, permeability, and potentially biorelevant solubilities at different ages, the PBCS Working Group focused on identifying age-specific issues that need to be considered in establishing a flexible, yet rigorous PBCS.

OBJECTIVE

We summarized the findings of the PBCS Working Group and provided insights into considerations required for the development of a PBCS.

METHODS

Through several meetings conducted both at The Eunice Kennedy Shriver National Institute of Child Health, Human Development-US Pediatric Formulation Initiative Workshop (November 2011) and via teleconferences, the PBCS Working Group considered several high-level questions that were raised to frame the classification system. In addition, the PBCS Working Group identified a number of knowledge gaps that need to be addressed to develop a rigorous PBCS.

RESULTS

It was determined that for a PBCS to be truly meaningful, it needs to be broken down into several different age groups that account for developmental changes in intestinal permeability, luminal contents, and gastrointestinal (GI) transit. Several critical knowledge gaps were identified, including (1) a lack of fully understanding the ontogeny of drug metabolizing enzymes and transporters along the GI tract, in the liver, and in the kidney; (2) an incomplete understanding of age-based changes in the GI, liver, and kidney physiology; (3) a clear need to better understand age-based intestinal permeability and fraction absorbed required to develop the PBCS; (4) a clear need for the development and organization of pediatric tissue biobanks to serve as a source for ontogenic research; and (5) a lack of literature published in age-based pediatric pharmacokinetics to build physiologically- and population-based pharmacokinetic (PBPK) databases.

CONCLUSIONS

To begin the process of establishing a PBPK model, 10 pediatric therapeutic agents were selected (based on their adult BCS classifications). These agents should be targeted for additional research in the future. The PBCS Working Group also identified several areas where greater emphasis on research was needed to enable the development of a PBCS.

Paradigm of Time-sequence Development of the Intestine of Suckling Piglets with Microarray

The interaction of the genes involved in intestinal development is the molecular basis of the regulatory mechanisms of intestinal development. The objective of this study was to identify the significant pathways and key genes that regulate intestinal development in Landrace piglets, and elucidate their rules of operation. The differential expression of genes related to intestinal development during suckling time was investigated using a porcine genome array. Time sequence profiles were analyzed for the differentially expressed genes to obtain significant expression profiles. Subsequently, the most significant profiles were assayed using Gene Ontology categories, pathway analysis, network analysis, and analysis of gene co-expression to unveil the main biological processes, the significant pathways, and the effective genes, respectively. In addition, quantitative real-time PCR was carried out to verify the reliability of the results of the analysis of the array. The results showed that more than 8000 differential expression transcripts were identified using microarray technology. Among the 30 significant obtained model profiles, profiles 66 and 13 were the most significant. Analysis of profiles 66 and 13 indicated that they were mainly involved in immunity, metabolism, and cell division or proliferation. Among the most effective genes in these two profiles, CN161469, which is similar to methylcrotonoyl-Coenzyme A carboxylase 2 (beta), and U89949.1, which encodes a folate binding protein, had a crucial influence on the co-expression network.

Small bowel endoscopy in children

Endoscopic investigation of small bowel pathology in children has historically been difficult due to location, length and tortuosity of the small bowel. Recently, video capsule endoscopy and balloon-assisted enteroscopy techniques have evolved as new diagnostic tools and are increasingly used in the paediatric population. In this review the current literature is appraised to define the clinical indications and practical aspects of capsule endoscopy and balloon-assisted enteroscopy in children.

Endodermal Hedgehog signals modulate Notch pathway activity in the developing digestive tract mesenchyme

The digestive tract epithelium and its adjoining mesenchyme undergo coordinated patterning and growth during development. The signals they exchange in the process are not fully characterized but include ligands of the Hedgehog (Hh) family, which originate in the epithelium and are necessary for mesenchymal cells to expand in number and drive elongation of the developing gut tube. The Notch signaling pathway has known requirements in fetal and adult intestinal epithelial progenitors. We detected Notch pathway activity in the embryonic gut mesenchyme and used conditional knockout mice to study its function. Selective disruption of the Notch effector gene RBP-Jκ (Rbpj) in the mesenchyme caused progressive loss of subepithelial fibroblasts and abbreviated gut length, revealing an unexpected requirement in this compartment. Surprisingly, constitutive Notch activity also induced rapid mesenchymal cell loss and impaired organogenesis, probably resulting from increased cell death and suggesting the need for a delicate balance in Notch signaling. Because digestive tract anomalies in mouse embryos with excess Notch activity phenocopy the absence of Hh signaling, we postulated that endodermal Hh restrains mesenchymal Notch pathway activity. Indeed, Hh-deficient embryos showed Notch overactivity in their defective gut mesenchyme and exposure to recombinant sonic hedgehog could override Notch-induced death of cultured fetal gut mesenchymal cells. These results reveal unexpected interactions between prominent signals in gastrointestinal development and provide a coherent explanation for Hh requirements in mesenchymal cell survival and organ growth.

Diagnosis and treatment of small bowel diseases are advanced by capsule endoscopy and double-balloon enteroscopy

In 2001, new endoscopic procedures for the small bowel, capsule endoscopy (CE) and double-balloon enteroscopy (DBE), were introduced into regular clinical practice. These methods were significant breakthroughs for imaging examination of the small bowel. The methods have different characteristics with regard to their approach into the target organ; however, common to both is the feature of enabling rapid total observation of the small bowel. CE is the first safe, non-invasive well-tolerated procedure and can be performed in any condition. The examination time is about 8 h and the patient can spend the time freely. CE can demonstrate active bleeding or neoplasm in the small bowel, which other modalities cannot detect. DBE, which was developed by Yamamoto, employs two balloons combined with an overtube and allows deeper insertion into the small bowel, and can be a modality for examination of the entire small bowel with combined oral and anal approaches. This modality enables biopsy specimens to be taken, polyps to be resected and hemostatic procedures to be performed throughout the small bowel. The understanding of small bowel disease is being extended by using CE and DBE for diagnosis. CE is considered to be superior for the first examination of the small bowel and DBE is useful for detailed examination and endoscopic therapy. Further clinical study of unknown small bowel disorders using these two modalities and algorithms for the management of small bowel disorders are required.