Endoscopic appearance and location dictate diagnostic yield of biopsies in eosinophilic oesophagitis.

BACKGROUND: Acknowledging that eosinophilic esophagitis (EoE) is a disease with variable involvement throughout the oesophagus, studies have suggested a minimum of five biopsies to diagnose EoE. Although it is accepted that furrows and exudates appear to represent areas of inflammation, no research to date has looked specifically at EoE endoscopic findings to see if eosinophilic infiltrate correlates with specific endoscopic findings. AIM: To evaluate the distribution of eosinophils in EoE and determine whether endoscopic appearances predict the degree of eosinophilia at various locations of the oesophagus. METHODS: We performed a prospective cross sectional study of EoE (treated and untreated) patients to study the distribution of eosinophils according to endoscopic findings. The oesophagus of 10 EoE patients were biopsied up to 32 times in a circumferential manner. The mucosal changes were documented at the site of each biopsy. Histological determination of eosinophil counts and related histopathology of the oesophagus were then correlated with endoscopic findings. Similar biopsy assessments were made in treated (resolved) EoE patients (n = 6) to determine the permanence of specific endoscopic appearances. RESULTS: A total of 16 patients were biopsied (10 EoE, 6 treated EoE). A total of 432 biopsies were obtained in all with 294 biopsies from 10 EoE subjects. Eosinophil density was increased distally in the majority of EoE patients. Biopsies performed in areas of exudates and furrows demonstrated higher eosinophil counts. Lines and normal-appearing oesophagi in EoE subjects were not commonly associated with elevated eosinophil counts (>15 eos/HPF). Rings alone without associated furrows or plaques did not demonstrate elevated eosinophil counts and were seen in resolved EoE (Rx-EoE) as well as in active EoE patients. CONCLUSIONS: Eosinophilic esophagitis remains a variable disease with some patients manifesting extensive disease throughout the oesophagus. Characteristics of furrows and exudates found during endoscopy are associated with higher peak eosinophil counts, requiring fewer biopsies to make a diagnosis. Lines and otherwise normal appearances of the oesophagus suggest a milder mucosal eosinophilia, requiring substantial biopsies to adequately identify fields with diagnostic eosinophil counts.

Aggregation kinetics of colloidal particles measured by gas-phase differential mobility analysis.

We demonstrate the utility of electrospray gas-phase ion-mobility analysis as a new method to investigate nanoparticle flocculation, or aggregation. Au nanoparticle (Au-NP) solutions were sampled via electrospray (ES), followed by differential ion-mobility analysis (DMA) to determine the particle mobility distribution. Multimodal size distributions obtained with ES-DMA indicated the presence of single Au-NPs (monomer) as well as larger Au-NP clusters such as dimers, trimers, and tetramers under specific solution conditions. The fraction of each aggregate species as a function of time was quantitatively characterized, from which the degree of aggregation, aggregation rate, and stability ratio at different ionic strengths were determined. The latter enabled the extraction of a surface potential (or surface charge density) of 64 +/- 2 mV for 10 nm Au-NPs, which is in good agreement with values obtained from other methods, thus validating our approach. Our results show that ES-DMA is a valuable tool for quantitatively probing the early stages of colloidal aggregation or as a preparatory tool for the size election of aggregates.

Gas-phase ion-mobility characterization of SAM-functionalized Au nanoparticles.

We present results of a systematic examination of functionalized gold nanoparticles (Au-NPs) by electrospray-differential mobility analysis (ES-DMA). Commercially available, citrate-stabilized Au colloid solutions (10-60 nm) were sized using ES-DMA, from which changes in particle size of less than 0.3 nm were readily discerned. It was found that the formation of salt particles and the coating of Au-NPs by salt during the electrospray process can interfere with the mobility analysis, which required the development of sample preparation and data correction protocols to extract correct values for the Au-NP size. Formation of self-assembled monolayers (SAMs) of alkanethiol molecules on the Au-NP surface was detected from a change in particle mobility, which could be modeled to extract the surface packing density of SAMs. A gas-phase temperature-programmed desorption (TPD) kinetic study of SAMs on Au-NPs found the data to be consistent with a second-order Arrhenius-based rate law, yielding an Arrhenius factor of 1.0 x 10 (11) s (-1) and an activation energy approximately 105 kJ/mol. For the size range of SAM-modified Au-NP we considered, the effect of surface curvature on the energetics of binding of carboxylic acid terminated SAMs is evidently negligible, with binding energies determined by TPD agreeing with those reported for the same SAMs on planar surfaces. This study suggests that the ES-DMA can be added to the tool set of characterization methods used to study the structure and properties of coated nanoparticles.