Origin of α and ß relaxations of Nafion.

Our experiments disentangle the low and high frequency dispersions in perfluorosulfonate ionomer solutions and membranes, providing a reasonable model for understanding these relaxations. Dielectric spectroscopy (DS) and small angle x-ray scattering (SAXS) measurements revealed that the dielectric relaxations observed at low (α relaxation) and high (ß relaxation) frequencies show typical features of the longitudinal and radial polarization, respectively, of rodlike polymeric aggregates. Such relaxations were attributed to counterion fluctuations in the vicinity of sulfonic acid groups, in resemblance with polyelectrolytes. Characteristic correlation lengths calculated from both DS and SAXS data are in good agreement adding further evidence to the proposed model. Such description provides insights for the understanding of the crossover from polyelectrolytes, dominated by charge repulsion, to ionomers, dominated by dipolar attraction.

LaNiO3 nanotubes produced using a template-assisted method.

We have studied the experimental conditions needed to produce LaNiO3 (LNO) nanostructures using a template-assisted method. In this route, a mesoporous anodic aluminum oxide template was filled with a chemical solution that had been prepared with polymeric precursors route. The precursor solutions and synthesized samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis, infrared spectroscopy and high-resolution scanning electron microscopy (HRSEM). The XRD results for the samples that were heat-treated at 700 degrees C revealed that these samples crystallize in a perovskite-like LaNiO3 structure. HRSEM images revealed that the samples prepared with different deposition times (0.5, 1 and 2 h) promoted the formation of LaNiO3 nanotubes with different wall thicknesses.

European guidelines for quality assurance in colorectal cancer screening and diagnosis. First Edition--Professional requirements and training.

Multidisciplinary, evidence-based guidelines for quality assurance in colorectal cancer screening and diagnosis have been developed by experts in a project coordinated by the International Agency for Research on Cancer. The full guideline document covers the entire process of population-based screening. It consists of 10 chapters and over 250 recommendations, graded according to the strength of the recommendation and the supporting evidence. The 450-page guidelines and the extensive evidence base have been published by the European Commission. The chapter on professional requirements and training includes 23 graded recommendations. The content of the chapter is presented here to promote international discussion and collaboration by making the principles and standards recommended in the new EU Guidelines known to a wider professional and scientific community. Following these recommendations has the potential to enhance the control of colorectal cancer through improvement in the quality and effectiveness of surveillance and other elements in the screening process, including multi-disciplinary diagnosis and management of the disease.

European guidelines for quality assurance in colorectal cancer screening and diagnosis. First Edition--Quality assurance in endoscopy in colorectal cancer screening and diagnosis.

Multidisciplinary, evidence-based guidelines for quality assurance in colorectal cancer screening and diagnosis have been developed by experts in a project coordinated by the International Agency for Research on Cancer. The full guideline document covers the entire process of population-based screening. It consists of 10 chapters and over 250 recommendations, graded according to the strength of the recommendation and the supporting evidence. The 450-page guidelines and the extensive evidence base have been published by the European Commission. The chapter on quality assurance in endoscopy includes 50 graded recommendations. The content of the chapter is presented here to promote international discussion and collaboration by making the principles and standards recommended in the new EU Guidelines known to a wider professional and scientific community. Following these recommendations has the potential to enhance the control of colorectal cancer through improvement in the quality and effectiveness of endoscopy and other elements in the screening process, including multidisciplinary diagnosis and management of the disease.

Feasibility of stomach exploration with a guided capsule endoscope.

BACKGROUND AND STUDY AIMS: Video capsule endoscopy has been established in diagnosis of small-bowel disease and has been evaluated for esophageal pathology and recently for colorectal diagnostics. Gastric capsule endoscopy has not hitherto been feasible due to the stomach's large surface area and volume. We present the first application of a magnetically navigated capsule in the human stomach. PATIENTS AND METHODS: 29 volunteers and 24 patients (men 42, women 11; mean age 47.5 years) were included in a feasibility study. Low-level magnetic fields were used to maneuver the double-sensor video capsule within the human stomach with an air-water interface provided by ingestion of 1300 ml water within 1 hour before examination. Visualization of all parts of the stomach was attempted; time for visualization was recorded, and a subjective assessment of completeness of visualization was documented. RESULTS: There was technical failure in one individual; thus technical success rate was 98 %. In the 52 remaining cases, examiners assessed that the antrum, body, fundus, and cardia were fully visualized in 98 %, 96 %, 73 % and 75 %, respectively. Mean duration of examinations was 30 minutes (range 8 - 50), with a longer time (mean 37 minutes) for volunteers for study reasons. In total, 30 findings were identified: 14 were detected by both gastroscopy and capsule, 10 lesions were identified by guided capsule examination only, 6 by gastroscopy only. No significant capsule-related adverse events occurred. CONCLUSION: Magnetically navigated video capsule endoscopy appears to be feasible and sufficiently accurate for gastric examination. It may permit endoscopic examinations that are more patient-friendly and without sedation. Comparative studies are under way.

European Society of Gastrointestinal Endoscopy (ESGE) guideline: the use of electrosurgical units.

Electrosurgery is used in the majority of endoscopic therapeutic procedures. An understanding of the fundamental electrosurgical principles and various settings available on electrosurgical units is essential for the safe and effective use of electrosurgery during endoscopy. The aims of these technical guidelines are to: (1) expose physical principles relevant to the understanding of electrosurgery during endoscopy; (2) describe and provide practical recommendations regarding electrosurgical units that are commonly in use; (3) discuss the clinical relevance of technologies recently implemented in newer electrosurgical units; and (4) review factors relevant to commonly performed therapeutic procedures, including polypectomy, sphincterotomy, contact thermal hemostasis, and argon plasma coagulation.

European Society of Gastrointestinal Endoscopy (ESGE): recommendations (2009) on clinical use of video capsule endoscopy to investigate small-bowel, esophageal and colonic diseases.

These recommendations on video capsule endoscopy, an emerging technology with an impact on the practice of endoscopy, were developed by the European Society of Gastrointestinal Endoscopy (ESGE) Guidelines Committee. The first draft of each section was prepared by one or two members of the writing team, who were selected as experts on the content of that section on the basis of their published work. They used evidence-based methodology, performing MEDLINE and PubMed literature searches to identify relevant clinical studies. Abstracts from scientific meetings were included only if there was no published full paper on a particular topic. If there was disagreement, the first author of the Guideline made the final decision. Recommendations were graded according to the strength of the supporting evidence. The draft guideline was critically reviewed by all authors and submitted to the ESGE councillors for their critical review before approval of the final document. The ESGE Guidelines Committee acknowledges that this document is based on a critical review of the data available at the time of preparation and that further studies may be needed to clarify some aspects. Moreover, this Guideline may be revised as necessary to account for changes in technology, new data, or other aspects of clinical practice. This document should be regarded as supplying recommendations only to gastroenterologists in providing care to their patients. It is not a set of rules and should not be construed as establishing a legal standard of care, or as encouraging, advocating, requiring, or discouraging any particular treatment. These recommendations must be interpreted according to the clinician's knowledge, expertise, and clinical judgment in the management of individual patients and, if necessary, a course of action that varies from recommendations must be undertaken.

World Gastroenterology Organization Practice Guidelines for the diagnosis and management of IBD in 2010.

Inflammatory bowel disease (IBD) represents a group of idiopathic, chronic, inflammatory intestinal conditions. Its two main disease categories are: Crohn's disease (CD) and ulcerative colitis (UC), which feature both overlapping and distinct clinical and pathological features. While these diseases have, in the past, been most evident in the developed world, their prevalence in the developing world has been gradually increasing in recent decades. This poses unique issues in diagnosis and management which have been scarcely addressed in the literature or in extant guidelines. Depending on the nature of the complaints, investigations to diagnose either form of IBD or to assess disease activity will vary and will also be influenced by geographic variations in other conditions that might mimic IBD. Similarly, therapy varies depending on the phenotype of the disease being treated and available resources. The World Gastroenterology Organization has, accordingly, developed guidelines for diagnosing and treating IBD using a cascade approach to account for variability in resources in countries around the world.

Optimal preparation for small bowel examinations with video capsule endoscopy.

BACKGROUND: Video capsule endoscopy is a major advance for small bowel exploration. Although the clinical benefit is well accepted, there are still unresolved issues concerning patient preparation. AIM: This study was set up in order to clarify the clinical benefit of small bowel preparation and give advices in order to obtain the best results for this expensive device. METHOD: 116 patients were randomised in 3 centres between two preparations from the traditional liquid diet versus polyethylene glycol colonoscopy-like preparation. External viewer monitoring and recording pictures were focused on image quality, bubbles or diet residues. Picture qualities were assessed blindly. RESULTS: For jejunal exploration no differences were noticed between the two preparations but for the ileum, polyethylene glycol preparation gives significant better results than liquid diet: air bubbles (64.4% versus 29.8% p<0.05); opaque residue (83.1% versus 38.6% p<0.05). External viewer was useful in order to use prokinetic drugs in case of delayed gastric emptying. CONCLUSION: The result leads to a new advice for colleagues in handling patients in order to improve the diagnosis yield by using a modified polyethylene glycol preparation.

Narrow-band imaging in digestive endoscopy.

The application of opto-electronics in video-endoscopes improves the accuracy in diagnosis, through image processing and digital technology. Narrow Band Imaging (NBI), consists of using interference filters for the illumination of the target in narrowed blue and green bands of the spectrum. NBI is combined with magnifying endoscopy using an objective macro or an optical zoom. The NBI technique developed by Olympus Medical Systems is now available in the most recent models of video-endoscopes that use the non-sequential system of illumination (Lucera Spectrum) or the sequential R/G/B system of illumination (Exera II). The major contribution of the technique is in the characterization (analysis after detection) of the flat and superficial neoplastic areas of the digestive mucosa, with a specific application to the identification of intestinal metaplasia and early neoplastic changes in the Barrett's esophagus. The technique also proves helpful for the assessment of the vascular pattern in chronic inflammatory disorders of the digestive mucosa.

Narrow band imaging: a wide field of possibilities.

The application of opto-electronic in video-endoscopes aims to improve accuracy in diagnosis, through image processing and digital technology. Narrow band imaging (NBI), one of the most recent techniques, consists of using interference filters for the illumination of the target in narrowed red, green, and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels in the mucosa and increases the contrast of the epithelial surface and of the subjacent vascular network. NBI is combined to magnifying endoscopy with an optical zoom. After being studied in prototypes the opto-electronic technique, now available in the most recent models of video-endoscopes that use the sequential R/G/B system of illumination, should be adapted in the near future for the instruments utilizing the non-sequential system of illumination. This new technique aims to characterize the surface of the distinct types of digestive epithelia, including intestinal metaplasia in the Barrett's esophagus. The technique also allows characterizing the disorganization of the vascular pattern in inflammatory disorders of the digestive mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel.

Use of sedation for routine diagnostic upper gastrointestinal endoscopy: a European Society of Gastrointestinal Endoscopy Survey of National Endoscopy Society Members.

BACKGROUND/AIMS: Sedation rates may vary among countries, depending on patients' and endoscopists' preferences. The aim of this survey was to investigate the rate of using premedication for routine diagnostic upper gastrointestinal (UGI) endoscopy in endoscopy societies, members of the European Society of Gastrointestinal Endoscopy (ESGE). METHODS: We evaluated a multiple-choice questionnaire which was e-mailed to representatives of national endoscopy societies, which are members of the ESGE. The questionnaire had 14 items referring to endoscopy practices in each country and the representatives' endoscopy units. RESULTS: The response rate was 76% (34/45). In 47% of the countries, less than 25% of patients undergo routine diagnostic UGI endoscopy with conscious sedation. In 62% of the responders' endoscopy units, patients are not asked their preference for sedation and do not sign a consent form (59%). Common sedatives in use are midazolam (82%), diazepam (38%) or propofol (47%). Monitoring equipment is not available 'in most of the endoscopy units' in 46% (13/28) of the countries. Though they were available in 91% of the national representatives' endoscopy units, they are rarely (21%) used to monitor unsedated routine diagnostic UGI endoscopy. CONCLUSIONS: In about 50% of ESGE-related countries, less than 25% of patients are sedated for routine diagnostic UGI endoscopy. Major issues to improve include availability of monitoring equipment and the use of a consent form.

Similar performance but higher cholecystitis rate with covered biliary stents: results from a prospective multicenter evaluation.

BACKGROUND AND STUDY AIMS: Endoscopic biliary stenting is now a well-established treatment method in patients with unresectable malignant biliary obstruction. Despite advances with metal stents, the problem of stent occlusion has not yet been resolved. Covered metal stents could reduce the occlusion rate by preventing tumor ingrowth, but have not been well evaluated. A prospective multicenter study was therefore conducted to evaluate the efficacy and disadvantages of covered Wallstents. PATIENTS AND METHODS: Covered Wallstents were implanted endoscopically in 62 patients with inoperable distal malignant biliary obstruction. Complications, stent patency, and patient survival were analyzed. RESULTS: Stent insertion was achieved in 61 of the 62 patients (98.4 %). Procedure-related complications were observed in four patients, consisting of minor pancreatitis (n = 2) and abdominal pain due to stent expansion (n = 2). There was no procedure-related mortality. Seven patients died too early for proper assessment, so that a total of 54 patients were ultimately evaluated. Stent dysfunction occurred in 17 of the 54 patients (31.5 %). The reasons for dysfunction were proximal tumor overgrowth (n = 5), migration (n = 3), lithiasis or food impaction (n = 3), cholangitis without the need for a repeat biliary intervention (n = 5), and unknown (n = 1). The median period of stent patency was 142 days. No tumor ingrowth was observed. Acute cholecystitis was diagnosed in five patients (10 %) and was responsible for one death. Three stents were successfully removed. CONCLUSIONS: Covered biliary metal stents are effective for the drainage of distal malignant biliary obstruction, with a dysfunction rate apparently similar to that of uncovered stents. However, the risk of acute cholecystitis appears to be a major concern with this type of stent in patients with gallbladder in situ. Further comparative studies are needed.

Does chromoendoscopy with structure enhancement improve the colonoscopic adenoma detection rate?

BACKGROUND AND STUDY AIMS: Colonoscopy is still considered the standard investigation for the detection of colorectal adenomas, but the miss rate, especially for small and flat lesions, remains unacceptably high. Chromoscopy has been shown to increase the yield for lesion detection in inflammatory bowel disease. The aim of this randomized prospective study was to determine whether a combination of chromoscopy and structure enhancement could increase the adenoma detection rate in high-risk patients. PATIENTS AND METHODS: All patients included in the trial had a personal history of colorectal adenomas and/or a family history of colorectal cancer (but excluding genetic syndromes). They were randomized to one of two tandem colonoscopy groups, with the first pass consisting of conventional colonoscopy for both groups, followed by either chromoscopy and structure enhancement (the "study" group) or a second conventional colonoscopy (the control group) for the second-pass colonoscopy. All detected lesions was examined histopathologically after endoscopic resection or biopsy. The principal outcome parameter was the adenoma detection rate; the number, histopathology, and location of lesions was also recorded. RESULTS: A total of 292 patients were included in the study (146 patients in each group). The patients' demographic characteristics, the indications for colonoscopy, and the quality of bowel preparation were similar in the two groups. There was a significant difference between the two groups with respect to the median duration of the examination (18.9 minutes in the control group vs. 27.1 minutes for the study group, P < 0.001). Although more hyperplastic lesions were detected throughout the colon in the study group ( P = 0.033), there was no difference between the two groups in either the proportion of patients with at least one adenoma or in the total number of adenomas detected. Chromoscopy and structure enhancement diagnosed significantly more diminutive adenomas (< 5mm) in the right colon, compared with controls ( P = 0.039). CONCLUSIONS: On the basis of our results we cannot generally recommend the systematic use of chromoscopy and structure enhancement in a high-risk patient population, although the detection of small adenomas in the proximal colon was improved.

Narrow-band imaging: potential and limitations.

The purpose of introducing optical electronics into video endoscopes is to improve the accuracy of diagnosis through image processing and digital technology. Narrow-band imaging (NBI), one of the most recent techniques, involves the use of interference filters to illuminate the target in narrowed red, green and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels of the mucosa and increases the contrast between the epithelial surface and the subjacent vascular network. NBI can be combined with magnifying endoscopy with an optical zoom. The aim of this new technique is to characterize the surface of the distinct types of gastrointestinal epithelia - e. g., intestinal metaplasia in Barrett's esophagus. The technique may also make it possible to demonstrate disorganization of the vascular pattern in inflammatory disorders of the gastrointestinal mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel.