Impact of Developmental Age, Necrotizing Enterocolitis Associated Stress, and Oral Therapeutic Intervention on Mucus Barrier Properties.

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease of incompletely understood pathophysiology predominantly affecting premature infants. While NEC is associated with microbial invasion of intestinal tissues, and mucus modulates interactions between microbes and underlying tissues, variations in mucus barrier properties with NEC-associated risk factors have not been investigated. This study explored differences in mucus composition (total protein, DNA, mucin content, sialic acid, and immunoregulatory proteins), as well as structural and transport properties, assessed by tracking of particles and bacteria (E. coli and E. cloacae) with developmental age and exposure to NEC stressors in Sprague Dawley rats. Early developmental age (5 day old) was characterized by a more permeable mucus layer relative to 21 day old pups, suggesting immaturity may contribute to exposure of the epithelium to microbes. Exposure to NEC stressors was associated with reduced mucus permeability, which may aid in survival. Feeding with breastmilk as opposed to formula reduces incidence of NEC. Thus, NEC-stressed (N-S) rat pups were orally dosed with breastmilk components lysozyme (N-S-LYS) or docosahexaenoic acid (N-S-DHA). N-S-LYS and N-S-DHA pups had a less permeable mucus barrier relative to N-S pups, which suggests the potential of these factors to strengthen the mucus barrier and thus protect against disease.

Political psychophysiology A primer for interested researchers and consumers.

The past decade has seen a rapid increase in the number of studies employing psychophysiological methods to explain variation in political attitudes and behavior. However, the collection, analysis, and interpretation of physiological data present novel challenges for political scientists unfamiliar with the underlying biological concepts and technical skills necessary for utilizing this approach. Our objective in this article is to maximize the effectiveness of future work utilizing psychophysiological measurement by providing guidance on how the techniques can be employed most fruitfully as a complement to, not a replacement for, existing methods. We develop clear, step-by-step instructions for how physiological research should be conducted and provide a discussion of the issues commonly faced by scholars working with these measures. Our hope is that this article will be a useful resource for both neophytes and experienced scholars in lowering the start-up costs to doing this work and assessing it as part of the peer review process. More broadly, in the spirit of the open science framework, we aim to foster increased communication, collaboration, and replication of findings across political science labs utilizing psychophysiological methods.

Mucus models to evaluate the diffusion of drugs and particles.

Mucus is a complex hydrogel that acts as a natural barrier to drug delivery at different mucosal surfaces including the respiratory, gastrointestinal, and vaginal tracts. To elucidate the role mucus plays in drug delivery, different in vitro, in vivo, and ex vivo mucus models and techniques have been utilized. Drug and drug carrier diffusion can be studied using various techniques in either isolated mucus gels or mucus present on cell cultures and tissues. The species, age, and potential disease state of the animal from which mucus is derived can all impact mucus composition and structure, and therefore impact drug and drug carrier diffusion. This review provides an overview of the techniques used to characterize drug and drug carrier diffusion, and discusses the advantages and disadvantages of the different models available to highlight the information they can afford.

Lipids alter microbial transport through intestinal mucus.

Mucus constitutes a protective layer which coats the gastrointestinal tract, controlling interactions of both commensal and pathogenic microbes with underlying tissues. Changes to the mucus barrier, for example due to altered mucin expression or external stimuli, may impact interactions with microbes and thus potentially contribute to altered gut homeostasis, onset of inflammation, or pathogen invasion. Food-associated stimuli, including lipids, have been shown to change mucus barrier properties and reduce transport of model drug carriers through mucus. Here, we explore the impact of lipids, specifically triglycerides in a model intestinal medium mimicking a fed state, on Escherichia coli (E. coli) transport through mucus by directly imaging swimming patterns and analyzing associated changes in mucus structure. Lipids in model fed state intestinal contents reduced E. coli speed and track linearity within mucus. These changes may be due in part to changes in molecular interactions within the mucus network as well as crowding of the mucus network by lipid emulsion droplets, which visibly stay intact in the mucus gel. In addition, observed physical interactions between bacteria and lipid structures may impact microbial speed and trajectories. As lipids are normal food components and thus represent safe, mild stimuli, these results support exploration of lipid-based strategies to alter the mucus barrier to control interactions with microbes and potentially prevent microbial invasion of underlying epithelium.

Acute Exposure to Commonly Ingested Emulsifiers Alters Intestinal Mucus Structure and Transport Properties.

The consumption of generally regarded as safe emulsifiers has increased, and has been associated with an increased prevalence of inflammatory bowel and metabolic diseases, as well as an altered microbiome. The mucus barrier, which selectively controls the transport of particulates and microorganisms to the underlying epithelial layer, has been previously shown to be altered by dietary salts and lipids. However, the potential impact of emulsifiers on the protective mucus barrier, its permeability, and associated structural changes are not clear. In this study, we analyzed changes in the mucus barrier to both passively diffusing nanoparticles and actively swimming E. coli upon exposure to two emulsifiers, carboxymethylcellulose (CMC) and polysorbate 80 (Tween). When exposed to CMC, mucus pore size decreased, which resulted in significantly slower E. coli speed and particle diffusion rates through mucus. Tween exposure minimally impacted mucus microstructure and particle diffusion, but increased E. coli speed in mucus. Moreover, both emulsifiers appeared to alter mucus amount and thickness in rat intestinal tissue and mucus-producing cell cultures. These results indicate that acute exposure to emulsifiers impacts barrier and structural properties of intestinal mucus, modulating interactions between intestinal lumen contents, microbes, and underlying tissue, which may contribute to development of intestinal inflammation.

Emulation of Colonic Oxygen Gradients in a Microdevice.

Gut-on-a-chip in vitro modeling is an emerging field, as the human gut epithelium and gut microbiome have been recently identified as novel drug targets for a wide variety of diseases. Realistic in vitro gut models require a variety of precise environmental cues, such as chemical and gas gradients, in combination with substrates like mucus that support the growth of microbial communities. This technical brief describes a microfluidic architecture capable of developing a physiologically relevant oxygen gradient that emulates the oxygen profile proximal to the epithelial inner lining of the human colon. The device generates stable and repeatable defined oxygen gradients from 0% to 4 % partial pressure O2 over a length scale of hundreds of microns, and was applied to study the effects of oxygenation on the structure of native mucus that lines the colon wall. Using simulation as a design tool for hybrid gas-liquid microfluidic devices enables on-chip creation of defined, physiologically oxygen gradients. These microfluidic architectures have powerful potential applications for gut physiology, including providing optimal oxygenation conditions for the culture of mammalian epithelial cells in the gut lining, as well as creating a realistic mimic of the oxygen gradient found in the intestinal lumen for complex microbiome cultures.

Design, synthesis, and biological evaluation of steroidal analogs as estrogenic/anti-estrogenic agents.

Series of estrone based analogs were synthetically investigated at positions C-9, C-11, C-16, and C-17 positions, to be biologically evaluated via assessment of cell proliferation, cytotoxicity, and estrogenic/anti-estrogenic activity. LA-7 and LA-10 revealed their potential to exhibit inhibitory estrogenic profile. This was further validated by Estrogen Receptor-α (ER-α) and Estrogen Receptor-ß (ER-ß) competitive binding assays to reveal the high selective affinity of LA-7 towards ER-α at 5.49µM, while LA-10 did not show any binding affinity towards neither ER-α nor ER-ß; suggesting another mechanism for inhibition. This was validated by in silico molecular docking simulations of LA-7 to reveal the optimum binding affinity of LA-7 towards ER-α.

Mucus Barriers to Microparticles and Microbes are Altered in Hirschsprung's Disease.

Mucus forms a protective hydrogel layer over the intestinal epithelium, presenting a selective and robust barrier to the uptake of particulates and microbe invasion. Disease can alter mucus production and composition, thus potentially modifying mucosal barrier properties. Hirschsprung's disease (HD) is a developmental abnormality of the nervous system often complicated by intestinal infection. An investigation of colonic mucus barrier properties in an HD animal model, endothelin receptor B mutant mice, revealed significantly reduced microsphere (passive) and microbe (active) transport rates (7-fold and 3.6-fold, respectively, in proximal colonic mucus) relative to wild-type. Transport differences were evident in both the ganglionic and aganglionic colon segments, in agreement with the risk of HD-associated enterocolitis after surgery to remove aganglionic colon segments. The development of therapies aimed at altering colonic mucus barrier properties could be explored towards preventing the onset of enterocolitis in HD.

Altered goblet cell differentiation and surface mucus properties in Hirschsprung disease.

Hirschsprung disease-associated enterocolitis (HAEC) leads to significant mortality and morbidity, but its pathogenesis remains unknown. Changes in the colonic epithelium related to goblet cells and the luminal mucus layer have been postulated to play a key role. Here we show that the colonic epithelium of both aganglionic and ganglionic segments are altered in patients and in mice with Hirschsprung disease (HSCR). Structurally, goblet cells were altered with increased goblet cell number and reduced intracellular mucins in the distal colon of biopsies from patients with HSCR. Endothelin receptor B (Ednrb) mutant mice showed increased goblet cell number and size and increased cell proliferation compared to wild-type mice in aganglionic segments, and reduced goblet cell size and number in ganglionic segments. Functionally, compared to littermates, Ednrb-/- mice showed increased transepithelial resistance, reduced stool water content and similar chloride secretion in the distal colon. Transcript levels of goblet cell differentiation factors SPDEF and Math1 were increased in the distal colon of Ednrb-/- mice. Both distal colon from Ednrb mice and biopsies from HSCR patients showed reduced Muc4 expression as compared to controls, but similar expression of Muc2. Particle tracking studies showed that mucus from Ednrb-/- mice provided a more significant barrier to diffusion of 200 nm nanoparticles as compared to wild-type mice. These results suggest that aganglionosis is associated with increased goblet cell proliferation and differentiation and subsequent altered surface mucus properties, prior to the development of inflammation in the distal colon epithelium. Restoration of normal goblet cell function and mucus layer properties in the colonic epithelium may represent a therapeutic strategy for prevention of HAEC.

Financial impact of surgical site infections on hospitals: the hospital management perspective.

IMPORTANCE: Surgical site infections (SSIs) may increase health care costs, but few studies have conducted an analysis from the perspective of hospital administrators. OBJECTIVE: To determine the change in hospital profit due to SSIs. DESIGN: Retrospective study of data from January 1, 2007, to December 31, 2010. SETTING: The study was performed at 4 of The Johns Hopkins Health System acute care hospitals in Maryland: Johns Hopkins Bayview (560 beds); Howard County General Hospital (238 beds); The Johns Hopkins Hospital (946 beds); and Suburban Hospital (229 beds). PARTICIPANTS: Eligible patients for the study included those patients admitted to the 4 hospitals between January 1, 2007, and December 31, 2010, with complete data and the correct International Classification of Diseases, Ninth Revision code, as determined by the infection preventionist. Infection preventionists performed complete medical record review using National Healthcare Safety Network definitions to identify SSIs. Patients were stratified using the All Patient Refined Diagnosis Related Groups to estimate the change in hospital profit due to SSIs. EXPOSURE: Surgical site infections. MAIN OUTCOMES AND MEASURES: The outcomes of the study were the difference in daily total charges, length of stay (LOS), 30-day readmission rate, and profit for patients with an SSI when compared with patients without an SSI. The hypothesis, formulated prior to data collection, that patients with an SSI have higher daily total costs, a longer LOS, and higher 30-day readmission rates than patients without an SSI, was tested using a nonpaired Mann-Whitney U test, an analysis of covariance, and a Pearson χ2 test. Hospital charges were used as a proxy for hospital cost. RESULTS The daily total charges, mean LOS, and 30-day readmission rate for patients with an SSI compared with patients without an SSI were $7493 vs $7924 (P = .99); 10.56 days vs 5.64 days (P < .001); and 51.94 vs 8.19 readmissions per 100 procedures (P < .001). The change in profit due SSIs was $2 268 589. CONCLUSIONS AND RELEVANCE: The data suggest that hospitals have a financial incentive to reduce SSIs, but hospitals should expect to see an increase in both cost and revenue when SSIs are reduced.