The sorption dynamics of C 3 hydrocarbons over carbon nanotubes

Carbon nanotubes obtained by the catalytic vapor deposition (CVD) method were purified by various procedures to obtain samples in pure and well-defined forms. The frequency response (FR) technique was employed to determine the sorption dynamics of C3-hydrocarbons in these samples. Two parallel sorption processes were found, characterized by different sorption capacities and time constants and were assigned to sorption on the convex and concave surfaces of the carbon tubes, respectively. Over a carbon nanotube sample at low coverage the mass transport is little influenced by the different chemical nature of the various C3 hydrocarbons. However the dynamic sorption properties of carbon nanotube preparations were shown to be strongly affected by the absence or presence of surface functional groups on the outer and inner surfaces of the tube walls. Different rate-determining mechanisms were observed for the samples functionalized to different extents

Evaluation of a minimally invasive cell sampling device coupled with assessment of trefoil factor 3 expression for diagnosing Barrett's esophagus: a multi-center case-control study.

BACKGROUND: Barrett's esophagus (BE) is a commonly undiagnosed condition that predisposes to esophageal adenocarcinoma. Routine endoscopic screening for BE is not recommended because of the burden this would impose on the health care system. The objective of this study was to determine whether a novel approach using a minimally invasive cell sampling device, the Cytosponge, coupled with immunohistochemical staining for the biomarker Trefoil Factor 3 (TFF3), could be used to identify patients who warrant endoscopy to diagnose BE. METHODS AND FINDINGS: A case-control study was performed across 11 UK hospitals between July 2011 and December 2013. In total, 1,110 individuals comprising 463 controls with dyspepsia and reflux symptoms and 647 BE cases swallowed a Cytosponge prior to endoscopy. The primary outcome measures were to evaluate the safety, acceptability, and accuracy of the Cytosponge-TFF3 test compared with endoscopy and biopsy. In all, 1,042 (93.9%) patients successfully swallowed the Cytosponge, and no serious adverse events were attributed to the device. The Cytosponge was rated favorably, using a visual analogue scale, compared with endoscopy (p < 0.001), and patients who were not sedated for endoscopy were more likely to rate the Cytosponge higher than endoscopy (Mann-Whitney test, p < 0.001). The overall sensitivity of the test was 79.9% (95% CI 76.4%-83.0%), increasing to 87.2% (95% CI 83.0%-90.6%) for patients with ≥3 cm of circumferential BE, known to confer a higher cancer risk. The sensitivity increased to 89.7% (95% CI 82.3%-94.8%) in 107 patients who swallowed the device twice during the study course. There was no loss of sensitivity in patients with dysplasia. The specificity for diagnosing BE was 92.4% (95% CI 89.5%-94.7%). The case-control design of the study means that the results are not generalizable to a primary care population. Another limitation is that the acceptability data were limited to a single measure. CONCLUSIONS: The Cytosponge-TFF3 test is safe and acceptable, and has accuracy comparable to other screening tests. This test may be a simple and inexpensive approach to identify patients with reflux symptoms who warrant endoscopy to diagnose BE

Risk stratification of Barrett's oesophagus using a non-endoscopic sampling method coupled with a biomarker panel: a cohort study.

BACKGROUND: Barrett's oesophagus predisposes to adenocarcinoma. However, most patients with Barrett's oesophagus will not progress and endoscopic surveillance is invasive, expensive, and fraught by issues of sampling bias and the subjective assessment of dysplasia. We investigated whether a non-endoscopic device, the Cytosponge, could be coupled with clinical and molecular biomarkers to identify a group of patients with low risk of progression suitable for non-endoscopic follow-up. METHODS: In this multicentre cohort study (BEST2), patients with Barrett's oesophagus underwent the Cytosponge test before their surveillance endoscopy. We collected clinical and demographic data and tested Cytosponge samples for a molecular biomarker panel including three protein biomarkers (P53, c-Myc, and Aurora kinase A), two methylation markers (MYOD1 and RUNX3), glandular atypia, and TP53 mutation status. We used a multivariable logistic regression model to compute the conditional probability of dysplasia status. We selected a simple model with high classification accuracy and applied it to an independent validation cohort. The BEST2 study is registered with ISRCTN, number 12730505. FINDINGS: The discovery cohort consisted of 468 patients with Barrett's oesophagus and intestinal metaplasia. Of these, 376 had no dysplasia and 22 had high-grade dysplasia or intramucosal adenocarcinoma. In the discovery cohort, a model with high classification accuracy consisted of glandular atypia, P53 abnormality, and Aurora kinase A positivity, and the interaction of age, waist-to-hip ratio, and length of the Barrett's oesophagus segment. 162 (35%) of 468 of patients fell into the low-risk category and the probability of being a true non-dysplastic patient was 100% (99% CI 96-100) and the probability of having high-grade dysplasia or intramucosal adenocarcinoma was 0% (0-4). 238 (51%) of participants were classified as of moderate risk; the probability of having high-grade dysplasia was 14% (9-21). 58 (12%) of participants were classified as high-risk; the probability of having non-dysplastic endoscopic biopsies was 13% (5-27), whereas the probability of having high-grade dysplasia or intramucosal adenocarcinoma was 87% (73-95). In the validation cohort (65 patients), 51 were non-dysplastic and 14 had high-grade dysplasia. In this cohort, 25 (38%) of 65 patients were classified as being low-risk, and the probability of being non-dysplastic was 96·0% (99% CI 73·80-99·99). The moderate-risk group comprised 27 non-dysplastic and eight high-grade dysplasia cases, whereas the high-risk group (8% of the cohort) had no non-dysplastic cases and five patients with high-grade dysplasia. INTERPRETATION: A combination of biomarker assays from a single Cytosponge sample can be used to determine a group of patients at low risk of progression, for whom endoscopy could be avoided. This strategy could help to avoid overdiagnosis and overtreatment in patients with Barrett's oesophagus. FUNDING: Cancer Research UK.The BEST2 study was funded by Cancer Research UKThis is the author accepted manuscript. The final version is available from Elsevier via https://doi.org/10.1016/S2468-1253(16)30118-

The sorption dynamics of C 3 hydrocarbons over carbon nanotubes

Carbon nanotubes obtained by the catalytic vapor deposition (CVD) method were purified by various procedures to obtain samples in pure and well-defined forms. The frequency response (FR) technique was employed to determine the sorption dynamics of C3-hydrocarbons in these samples. Two parallel sorption processes were found, characterized by different sorption capacities and time constants and were assigned to sorption on the convex and concave surfaces of the carbon tubes, respectively. Over a carbon nanotube sample at low coverage the mass transport is little influenced by the different chemical nature of the various C3 hydrocarbons. However the dynamic sorption properties of carbon nanotube preparations were shown to be strongly affected by the absence or presence of surface functional groups on the outer and inner surfaces of the tube walls. Different rate-determining mechanisms were observed for the samples functionalized to different extents

Study CONSORT diagram detailing the flow of control and Barrett's esophagus patients (cases) through the study.

<p>Patients who were unable to swallow the Cytosponge or whose Cytosponge sample failed processing were excluded from the study. Exact numbers of control and BE patients who successfully completed the study are noted.</p

Modeling of Cytosponge-TFF3 testing and risk stratification in the primary care population with reflux symptoms.

<p>Extrapolation of findings to a hypothetical population of 10,000 individuals with reflux symptoms using a sensitivity and specificity of 79.9% and 92.4%, respectively, for the TFF3 screen, and a sensitivity and specificity of 86% (95% CI of 65%–96%) and 100% (95% CI of 94.6%–100%), respectively, for <i>TP53</i> mutation screening for detection of HGD. The assumed prevalence of BE was 3%. In patients found to be high risk, endoscopy within 6–8 wk would be recommended. For low-risk patients, a repeat Cytosponge-TFF3 test would be performed at an interval of several years (exact timing to be determined) in case they had become TP53 positive over this time period. In the TFF3-negative arm, the repeat Cytosponge testing might not be necessary. If it took place, repeat testing would be recommended within 6 to 8 wk of the delivery of the TFF3-negative results.</p

TFF3 immunohistochemical staining of Cytosponge samples.

<p>TFF3 staining was performed on all Cytosponge samples to test the sensitivity and specificity of the Cytosponge-TFF3 test for diagnosing BE. TFF3 was scored in a binary fashion, with samples with one or more TFF3-positive goblet cells being classed as positive. Shown are immunohistochemical images illustrating examples of TFF3-negative and-positive staining at low magnification (100×) and high magnification (400×).</p