The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
BACKGROUND & AIMS - Penetration of the esophageal epithelium by food antigens is an early event in the pathogenesis of eosinophilic esophagitis (EoE), but the precise relationship among eosinophilia, dilated intercellular spaces (DIS), and decreased barrier function is unclear. We investigated the correlation between site-specific mucosal impedance (MI) measurements of ion flux and esophageal histology, and whether MI measurements can be used to distinguish between patients with active and inactive EoE.
METHODS - MI was measured (in Ω) in 10 patients with active EoE (>15 eosinophils [eos]/high-power field [HPF]) and in 10 with inactive EoE (<15 eos/HPF, as a result of treatment), and mucosal biopsy specimens were collected from 4 esophageal sites (2, 5, 10, and 15 cm above the Z-line). MI also was measured in 10 individuals without esophageal symptoms (controls). MI measurements, eos/HPF, and DIS grade were compared among patients with EoE and controls.
RESULTS - The esophageal MI values were significantly lower in patients with active EoE (1909 Ω) compared with inactive EoE (4349 Ω) or controls (5530 Ω) (P < .001). Biopsy specimens from 4 patients with active EoE contained fewer than 15 eos/HPF and lower-grade DIS than in patients with active disease. There were significant inverse correlations between MI and eos/HPF (rs = -.584), as well as between MI and DIS (rs = -.531; P < .001). The MI cut-off value of 2300 Ω identified patients with active EoE with 90% sensitivity and 91% specificity, and high-grade DIS with 89% sensitivity and 82% specificity.
CONCLUSIONS - In patients with EoE, eosinophilia and DIS correlate with MI measurements of ion flux. Endoscopic MI measurement in the esophagus is safe and easy to perform, and can be used to assess activity of diseases such as EoE.
Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.
BACKGROUND & AIMS - Current diagnostic tests for gastroesophageal reflux disease (GERD) are suboptimal and do not accurately and reliably measure chronicity of reflux. A minimally invasive device has been developed to assess esophageal mucosal impedance (MI) as a marker of chronic reflux. We performed a prospective longitudinal study to investigate MI patterns in patients with GERD and common nonreflux conditions, to assess MI patterns before and after treatment with proton pump inhibitors and to compare the performance of MI and wireless pH tests.
METHODS - We evaluated MI in 61 patients with erosive esophagitis, 81 with nonerosive but pH-abnormal GERD, 93 without GERD, 18 with achalasia, and 15 with eosinophilic esophagitis. MI was measured at the site of esophagitis and at 2, 5, and 10 cm above the squamocolumnar junction in all participants. MI was measured before and after acid suppressive therapy, and findings were compared with those from wireless pH monitoring.
RESULTS - MI values were signiﬁcantly lower in patients with GERD (erosive esophagitis or nonerosive but pH-abnormal GERD) or eosinophilic esophagitis than in patients without GERD or patients with achalasia (P < .001). The pattern of MI in patients with GERD differed from that in patients without GERD or patients with eosinophilic esophagitis; patients with GERD had low MI closer to the squamocolumnar junction, and values increased axially along the esophagus. These patterns normalized with acid suppressive therapy. MI patterns identified patients with esophagitis with higher levels of specificity (95%) and positive predictive values (96%) than wireless pH monitoring (64% and 40%, respectively).
CONCLUSIONS - Based on a prospective study using a prototype device, measurements of MI detect GERD with higher levels of specificity and positive predictive values than wireless pH monitoring. Clinical Trials.gov, Number: NCT01556919.
Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.
PURPOSE - Vascular endothelial growth factor (VEGF)-induced retinal vascular permeability contributes to diabetic macular edema (DME), a serious vision-threatening condition. Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) antagonist/reverse agonist, GSK0660, inhibits VEGF-induced human retinal microvascular endothelial cell (HRMEC) proliferation, tubulogenesis, and oxygen-induced retinal vasculopathy in newborn rats. These VEGF-induced HRMEC behaviors and VEGF-induced disruption of endothelial cell junctional complexes may well share molecular signaling events. Thus, we sought to examine the role of PPARβ/δ in VEGF-induced retinal hyperpermeability.
METHODS - Transendothelial electrical resistance (TEER) measurements were performed on HRMEC monolayers to assess permeability. Claudin-1/Claudin-5 localization in HRMEC monolayers was determined by immunocytochemistry. Extracellular signal-regulated protein kinases 1 and 2 (Erk 1/2) phosphorylation, VEGF receptor 1 (VEGFR1) and R2 were assayed by Western blot analysis. Expression of VEGFR1 and R2 was measured by quantitative RT-PCR. Last, retinal vascular permeability was assayed in vivo by Evans blue extravasation.
RESULTS - Human retinal microvascular endothelial cell monolayers treated with VEGF for 24 hours showed decreased TEER values that were completely reversed by the highest concentration of GSK0660 (10 μM) and PPARβ/δ-directed siRNA (20 μM). In HRMEC treated with VEGF, GSK0660 stabilized tight-junctions as evidenced by Claudin-1 staining, reduced phosphorylation of Erk1/2, and reduced VEGFR1/2 expression. Peroxisome proliferator-activated receptor β/δ siRNA had a similar effect on VEGFR expression and Claudin-1, supporting the specificity of GSK0660 in our experiments. Last, GSK0660 significantly inhibited VEGF-induced retinal vascular permeability and reduced retinal VEGFR1and R2 levels in C57BL/6 mice.
CONCLUSIONS - These data suggest a protective effect for PPARβ/δ antagonism against VEGF-induced vascular permeability, possibly through reduced VEGFR expression. Therefore, antagonism/reverse agonism of PPARβ/δ siRNA may represent a novel therapeutic methodology against retinal hyperpermeability and is worthy of future investigation.
Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Dopaminergic innervation of the extended amygdala regulates anxiety-like behavior and stress responsivity. A portion of this dopamine input arises from dopamine neurons located in the ventral lateral periaqueductal gray (vlPAG) and rostral (RLi) and caudal linear nuclei of the raphe (CLi). These neurons receive substantial norepinephrine input, which may prime them for involvement in stress responses. Using a mouse line that expresses eGFP under control of the tyrosine hydroxylase promoter, we explored the physiology and responsiveness to norepinephrine of these neurons. We find that RLi dopamine neurons differ from VTA dopamine neurons with respect to membrane resistance, capacitance and the hyperpolarization-activated current, Ih. Further, we found that norepinephrine increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) on RLi dopamine neurons. This effect was mediated through the α1 adrenergic receptor (AR), as the actions of norepinephrine were mimicked by the α1-AR agonist methoxamine and blocked by the α1-AR antagonist prazosin. This action of norepinephrine on sEPSCs was transient, as it did not persist in the presence of prazosin. Methoxamine also increased the frequency of miniature EPSCs, indicating that the α1-AR action on glutamatergic transmission likely has a presynaptic mechanism. There was also a modest decrease in sEPSC frequency with the application of the α2-AR agonist UK-14,304. These studies illustrate a potential mechanism through which norepinephrine could recruit the activity of this population of dopaminergic neurons.
Copyright © 2014 Elsevier Ltd. All rights reserved.
BACKGROUND - A significant percentage of breast cancer survivors are at risk for lymphedema for which lifelong self-care is required. Previous studies suggest that less than 50% of breast cancer survivors with lymphedema (BCS-LE) perform prescribed self-care tasks and that even wearing a compression sleeve, the most commonly reported self-care activity, is done irregularly. Reasons for poor self-care adherence include perceived lack of results from self-care (no available arm volume data) and perceived inability to manage the condition.
METHODS AND RESULTS - A two-part pilot study was conducted to: 1) develop and determine the feasibility of a self-measurement protocol using a single frequency bioelectrical impedance device; and 2) examine daily variation in extracellular volume in healthy and lymphedematous limbs. Healthy and BCS-LE volunteers were recruited to refine and test a self-measurement protocol. Volunteers were trained in the use of the device and measured for 5 consecutive days in a laboratory setting. They were then given the device to use at home for an additional 5 consecutive days of self-measurement. All volunteers completed each scheduled home measurement. Daily variability in both groups was noted.
CONCLUSIONS - Home self-measurement using bioelectrical impedance is feasible, acceptable, and captures change. This has implications for both self-care support and for the possibility of incorporating self-measurement using bioelectrical impedance in future clinical trials examining effectiveness of lymphedema treatment.
Establishment and maintenance of apico-basolateral trafficking pathways are critical to epithelial homeostasis. Loss of polarity and trafficking fidelity are thought to occur as a consequence of transformation; however, here we report that selective mistrafficking of the epidermal growth factor receptor (EGFR) ligand epiregulin (EREG) from the basolateral to the apical cell surface drives transformation. Normally, EREG is preferentially delivered to the basolateral surface of polarized Madin-Darby canine kidney cells. EREG basolateral trafficking is regulated by a conserved tyrosine-based basolateral sorting motif in its cytoplasmic domain (YXXΦ: Y(156)ERV). Both Y156 and V159 are required for basolateral sorting of EREG, because Y156A and V159G substitutions redirect EREG to the apical cell surface. We also show that basolateral sorting of EREG is adaptor protein 1B-independent. Apical mistrafficking of EREG has a distinctive phenotype. In contrast to transient EGFR tyrosine phosphorylation after basolateral EREG stimulation, apical EREG leads to prolonged EGFR tyrosine phosphorylation, which may be related, at least in part, to a lack of negative regulatory Y1045 phosphorylation and subsequent ubiquitylation. Notably, Madin-Darby canine kidney cells stably expressing apically mistrafficked EREG form significantly larger, hyperproliferative, poorly differentiated, and locally invasive tumors in nude mice compared with WT EREG-expressing cells.
Disturbance of the endothelial barrier is characterized by dramatic cytoskeleton reorganization, activation of actomyosin contraction and, finally, leads to intercellular gap formation. Here we demonstrate that the edemagenic agent, thrombin, causes a rapid increase in the human pulmonary artery endothelial cell (EC) barrier permeability accompanied by fast decreasing in the peripheral microtubules quantity and reorganization of the microtubule system in the internal cytoplasm of the EC within 5 min of the treatment. The actin stress-fibers formation occurs gradually and the maximal effect is observed relatively later, 30 min of the thrombin treatment. Thus, microtubules reaction develops faster than the reorganization of the actin filaments system responsible for the subsequent changes of the cell shape during barrier dysfunction development. Direct microtubules depolymerization by nocodazole initiates the cascade of barrier dysfunction reactions. Nocodazole-induced barrier disruption is connected directly with the degree of peripheral microtubules depolymerization. Short-term loss of endothelial barrier function occurs at the minimal destruction of peripheral microtubules, when actin filament system is still intact. Specifically, we demonstrate that the EC microtubule dynamics examined by time-lapse imaging of EB3-GFP comets movement has changed under these conditions: microtubule plus ends growth rate significantly decreased near the cell periphery. The microtubules, apparently, are the first target in the circuit of reactions leading to the pulmonary EC barrier compromise. Our results show that dynamic microtubules play an essential role in the barrier function in vitro; peripheral microtubules depolymerization is necessary and sufficient condition for initiation of endothelial barrier dysfunction.
Copyright © 2013 Wiley Periodicals, Inc.
Gastroesophageal reflux disease is increasingly associated with ear, nose, and throat symptoms, including laryngitis. Many patients are unaware of the gastroesophageal etiology of their symptoms. A variety of criteria are used to diagnose this condition, including laryngoscopy, esophagogastroduodenoscopy, and the use of ambulatory pH and impedance monitoring. However, no test serves as the gold standard for the diagnosis given their lack of sensitivity and specificity for reflux disease. Numerous trials have assessed the role of proton pump inhibitor therapy in patients with laryngopharyngeal reflux and most have revealed no benefit to acid suppression over placebo. Despite many uncertainties there has been some progress regarding the role of acid-suppressive therapy as well as other agents in this unique group of patients. In this review we explore therapeutic options and their rationale for patients with laryngeal signs and symptoms.
The regulation of cell motility is central to living systems. Consequently, cell migration assays are some of the most frequently used in vitro assays. This article provides a comprehensive, detailed review of in vitro cell migration assays both currently in use and possible with existing technology. Emphasis is given to two-dimensional migration assays using densely organized cells such as the scratch assay. Assays are compared and categorized in an outline format according to their primary biological readout and physical parameters. The individual benefits of the various methods and quantification strategies are also discussed. This review provides an in-depth, structured overview of in vitro cell migration assays as a means of enabling the reader to make informed decisions among the growing number of options available for their specific cell migration application.
The colonic epithelium is composed of a polarized monolayer sheathed by a layer of pericryptal myofibroblasts (PCMFs). We mimicked these cellular compartments in vitro to assess the effects of paracrine-acting PCMF-derived factors on tight junction (TJ) integrity, as measured by transepithelial electrical resistance (TER). Coculture with 18Co PCMFs, or basolateral administration of 18Co conditioned medium, significantly reduced TER of polarized Caco-2 cells. Among candidate paracrine factors, only keratinocyte growth factor (KGF) reduced Caco-2 TER; basolateral KGF treatment led to time- and concentration-dependent increases in claudin-2 levels. We also demonstrate that amphiregulin (AREG), produced largely by Caco-2 cells, increased claudin-2 levels, leading to epidermal growth factor receptor-mediated TER reduction. We propose that colonic epithelial TJ integrity can be modulated by paracrine KGF and autocrine AREG through increased claudin-2 levels. KGF-regulated claudin-2 induction may have implications for inflammatory bowel disease, where both KGF and claudin-2 are upregulated.