Search PubMed⌕ Search

Biomedical subjects

C Ell

Publications and source records attributed to C Ell.

At least 37 records · Page 2Linked to original sources
PubMed2004

Excitonic photoluminescence in semiconductor quantum wells: plasma versus excitons.

Time-resolved photoluminescence spectra after nonresonant excitation show a distinct 1s resonance, independent of the existence of bound excitons. A microscopic analysis identifies exciton and electron-hole plasma contributions. For low temperatures and low densities, the excitonic emission is extremely sensitive to details of the electron-hole-pair population making it possible to identify even minute fractions of optically active excitons.

Journal Article↗
PubMed2004

A new self-expanding nitinol stent (JoStent SelfX) for palliation of malignant biliary obstruction: a pilot study.

BACKGROUND AND STUDY AIMS: The JoStent SelfX is a new biliary uncovered self-expanding nitinol stent. The main advantage of this stent in comparison with the "gold standard" Wallstent is the minimal shortening (< 10 %) that occurs during stent deployment. A prospective feasibility study was conducted to evaluate the method of stent implantation and the stent's short-term efficacy. PATIENTS AND METHODS: Between April 2001 and December 2002, the JoStent SelfX was implanted in 20 patients with inoperable malignant biliary obstructions, mainly caused by pancreatic cancer (12 of 20). All patients underwent sphincterotomy prior to stent insertion. After implantation, laboratory parameters for cholestasis and expansion of the stent were checked over a period of several days. All patients were followed for 8 weeks after implantation to document early stent dysfunction. RESULTS: Stent implantation was easily managed and successful in all patients, with no technical problems. Prior bougienage was required in only one patient, who had a filiform stenosis. No stent retraction was observed during stent release. All stents showed full expansion within 5 days. No acute complications occurred. Adequate reduction in the elevated laboratory parameters for cholestasis was observed. Two patients had recurrent cholestasis and fever due to cholangitis, or stent occlusion caused by biliary sludge within 4 weeks. CONCLUSIONS: This new biliary metal stent is easily inserted and does not shorten during stent release, allowing precise positioning. No acute complications occurred, but there were two cases of early stent dysfunction. The role of the JoStent SelfX in comparison with other biliary stents will need to be evaluated in a multicenter trial with a larger number of patients, to investigate the long-term results.

Aged↗
PubMed2004

Histological analysis of endoscopic resection specimens from 326 patients with Barrett's esophagus and early neoplasia.

BACKGROUND AND STUDY AIMS: Endoscopic resection has been recommended as a local curative approach for Barrett's neoplasia, but large series are still rare. In the present study we analyzed the histological characteristics of endoscopic resection specimens of Barrett's neoplasia. PATIENTS AND METHODS: 742 endoscopic resection specimens obtained from 326 patients were assessed. The following histological characteristics were evaluated: type of neoplasia, grade of differentiation, depth of infiltration, invasion into lymphatic and blood vessels, and resection status (tumor-free margins were regarded as indicating R0 status). RESULTS: 31 patients had no neoplasia and were excluded from the analysis. Among the remaining 295 patients (711 resection specimens), histological findings were: low-grade intraepithelial neoplasia, 1.0 %; high-grade intraepithelial neoplasia, 2.7 %; and mucosal carcinoma 80.3 %. Carcinomas infiltrating the submucosal layer were rare (sm1 7.5 %; sm2 3.7 %; sm3 4.8 %), as were those invading lymph vessels (3.5 %), and there were none with venous invasion. Most of the carcinomas were well-differentiated (72.2 %), and many of these (92.7 %) were limited to the mucosa, in contrast to moderately and poorly differentiated carcinomas (73.7 % and 22.7 %, respectively). R0 status was achieved in 74.5 % of patients; in 47.8 % this was after repeated endoscopic resection. In 26.8 % of patients, R0 resection was achieved at the first attempt. CONCLUSIONS: Our study demonstrates that early Barrett's neoplasms removed by endoscopic resection are mostly limited to the mucosa, are well to moderately differentiated, and very rarely show invasion of the lymph or blood vessels. Although these lesions seem to be low risk with regard to metastatic spread and therefore treatable endoscopically, improved endoscopic resection methods for achieving one-piece (en bloc) R0 resection should be developed.

Adenocarcinoma↗
PubMed2004

Accuracy of staging in early oesophageal cancer using high resolution endoscopy and high resolution endosonography: a comparative, prospective, and blinded trial.

BACKGROUND AND AIMS: The increasing use of endoscopic resection for curative treatment of early oesophageal cancers requires accurate staging before therapy. In a prospective blinded trial, we compared staging of early oesophageal carcinoma using high resolution endoscopy (HR-E) with staging using high resolution endosonography (HR-EUS). PATIENTS AND METHODS: A total of 100 patients (89 men, 11 women; mean age 63.9 (10.8) years (range 31-91)) with a suspicion of early oesophageal adenocarcinoma (n = 81) or squamous cell carcinoma (n = 19) were enrolled in the study. After endoscopic staging with high resolution video endoscopy by two experienced endoscopists, HR-EUS was performed by an experienced endosonographer who was blinded to the endoscopic assessment. Results of the staging examinations were correlated with the histology of the resected tumours. RESULTS: Overall rates for accuracy of the endoscopic and endosonographic staging were 83.4% and 79.6%, respectively. Sensitivity for mucosal tumours (n = 68) was more than 90% (EUS 91.2%, endoscopy 94.1%) while sensitivity for submucosal tumours (n = 25) was lower, at 48% for EUS and 56% for endoscopic staging. A combination of the two techniques increased the sensitivity for submucosal tumours to 60%. Submucosal tumours in the tubular oesophagus were significantly better staged with HR-EUS than submucosal tumours close to the oesophagogastric junction (10/11 v 2/14; p<0.001). Tumours infiltrating the second and third submucosal layers were also more correctly diagnosed than tumours with slight infiltration of the first submucosal layer (sm1). CONCLUSIONS: The overall diagnostic accuracy of both HR-E and HR-EUS with a 20 MHz miniprobe in early oesophageal cancer was high (approximately 80%), with no significant differences between the two techniques. HR-E and HR-EUS provide a high level of diagnostic accuracy for mucosal tumours and submucosal tumours located in the tubular part of the oesophagus. With submucosal tumours located at the oesophagogastric junction or with infiltration of the first third of the submucosa however, the diagnostic accuracy of both techniques is not yet satisfactory.

Adenocarcinoma↗
PubMed2003

Histopathological diagnosis of Barrett's mucosa and associated neoplasias: results of a consensus conference of the Working Group for Gastroenterological Pathology of the German Society for Pathology on 22 September 2001 in Erlangen.

There are a number of difficulties regarding the diagnosis of Barrett's mucosa and the varying grades of neoplasia that may be associated with it. It was, therefore, the aim of a consensus conference of the Working Group for Gastroenterological Pathology within the German Society of Pathology to achieve standardisation regarding the following issues: definition and diagnostic criteria for Barrett's mucosa and its discrimination from intestinal metaplasia of the cardia, diagnostic criteria for intraepithelial neoplasia, number of biopsies necessary to establish the diagnosis, significance of additional immunohistochemical and/or molecular methods as well as importance of a second opinion in the diagnosis of intraepithelial neoplasia.

Barrett Esophagus↗
PubMed2003

[Histopathological diagnosis of Barrett's mucosa and associated neoplasias. Results of a consensus conference of the Working Group for "Gastroenterological Pathology of the German Society for Pathology" on 22 September 2001].

There are a number of difficulties regarding the diagnosis of Barrett's mucosa and the varying grades of neoplasia that may be associated with it. It was therefore the aim of a consensus conference of the "Working Group for Gastroenterological Pathology within the German Society of Pathology" to achieve standardization regarding the following issues: definition and diagnostic criteria for Barrett's mucosa and its discrimination from intestinal metaplasia of the cardia, diagnostic criteria for intraepithelial neoplasia, number of biopsies necessary to establish the diagnosis, significance of additional immunohistochemical and/or molecular biological methods as well as importance of a second opinion in the diagnosis of intraepithelial neoplasia.

Barrett Esophagus↗
PubMed2003

A randomized, blinded, prospective trial to compare the safety and efficacy of three bowel-cleansing solutions for colonoscopy (HSG-01*).

BACKGROUND AND STUDY AIMS: There are conflicting data regarding the optimal bowel preparation for colonoscopy. This study was carried out to compare the efficacy, safety, and tolerability of three widely used bowel lavage solutions: the standard polyethylene glycol-electrolyte solution based on the GoLytely formulation (PEG-EL1; Klean-Prep); a sulphate-free PEG-EL solution based on the NuLytely formulation (PEG-EL2, Endofalk); and a sodium phosphate preparation (NaP, Fleet Phospho-Soda). PATIENT AND METHODS: A total of 185 consecutive patients scheduled for elective colonoscopy were prospectively randomly assigned to undergo pre-colonoscopic bowel cleansing with either 4 l of PEG-EL1 (n=64), 3 l of PEG-EL2 (n=59), or 90 ml of NaP (n=62). The quality of preparatory colonic cleansing for each segment from the rectum to the ascending colon was scored on a five-level rating scale (1, very good to 5, very poor) by endoscopists who were blinded with regard to the type of preparation used. The primary outcome measure for the comparison of treatments was the "worst" score in any of the rated bowel segments. Safety and tolerability were evaluated by means of a symptom questionnaire completed by each patient immediately before the procedure. RESULTS: Of the 185 patients who were randomly assigned to one of the three treatments, 175 underwent colonoscopy and 173 were evaluable with regard to efficacy - 59, 54, and 60 patients treated with PEG-EL1, PEG-EL2, and NaP, respectively. The treatment groups were comparable with regard to the baseline characteristics. PEG-EL1 was statistically significantly superior to the other treatments in relation to the "worst cleansing" score ( P</=0.003). In addition, colonoscopic visualization was markedly better in each of the five bowel segments and general "very good" or "good" ratings were achieved in more than 90 % of patients treated with PEG-EL1. The percentages were consistently lower in the other two groups, particularly in the ascending colon. With the exception of the sigmoid, the differences in all segments of the large bowel were statistically significant (P</=0.04). Patient satisfaction was comparable between the treatment groups. Adverse events (mainly nausea/vomiting and abdominal pain) and deviations in laboratory values occurred more frequently in the NaP group. CONCLUSIONS: Preparatory PEG-EL1 (Klean-Prep) was significantly superior to PEG-EL2 (Endofalk) and NaP (Fleet Phospho-Soda) in achieving effective cleansing of the entire colon prior to colonoscopy. On the basis of these data, PEG-EL1 can be regarded as the "gold standard" for bowel cleansing prior to colonoscopy.

Adolescent↗
PubMed2003

Double-balloon enteroscopy: preliminary experience in patients with obscure gastrointestinal bleeding or chronic abdominal pain.

BACKGROUND AND STUDY AIMS: Even in the era of capsule endoscopy, diseases of the small bowel are sometimes difficult to diagnose, and endoscopic treatment is not possible without surgical laparotomy. The new method of carrying out enteroscopy using a double-balloon technique allows not only diagnostic but also therapeutic endoscopic interventions for lesions in the small bowel. Preliminary experience with this new method is reported here. PATIENTS AND METHODS: Between the end of March 2003 and August 2003, eight patients (four women, four men; mean age 59 +/- 23 years, range 20 - 90) with chronic gastrointestinal bleeding or abdominal pain, or both, underwent enteroscopy using the double-balloon technique. Seven of the patients had been suffering from chronic gastrointestinal bleeding for 56 +/- 49 months (range 3 - 120 months, median 48 months). The lowest hemoglobin levels ranged from 3.6 g/dl to 8.6 g/dl (mean 6.7 +/- 1.7 g/dl), and a mean of 7.6 +/- 5.6 (range 1 - 15) blood units had been transfused. Capsule endoscopy was carried out in six patients, revealing angiodysplasias in three, suspected Crohn's disease in one, fresh blood in the small bowel without a lesion in one, and a focal enanthema in another patient. RESULTS: Enteroscopy with the double-balloon technique was carried out using the oral approach in all patients and additionally with the anal approach in four patients. In two patients with multiple angiodysplasias, it was possible to examine the whole small bowel and to treat the angiodysplasias. All of the capsule endoscopy findings were confirmed; a definite bleeding source was found and treated in two patients with unclear bleeding, and in another patient the real bleeding source was found (not angiodysplasia). The enteroscopy system was easy to handle in all cases. No complications occurred. It was possible to carry out the procedure with the patients under sedoanalgesia. CONCLUSIONS: This new enteroscopy system is easy to handle and seems to be safe. Visualization of the whole small bowel is possible using both the oral and anal approaches. Enteroscopy with the double-balloon technique promises to become a standard method for diagnostic and therapeutic endoscopy of the small bowel without surgical laparotomy.

Abdominal Pain↗
PubMed2003

Improving endoscopic resolution and sampling: fluorescence techniques.

Gastrointestinal tumours are usually associated with a poor prognosis, as most are only diagnosed at an advanced stage. Every effort to improve intraluminal diagnosis in gastroenterology must therefore be aimed at diagnosing gastrointestinal tract tumours at the earliest stage possible.

Barrett Esophagus↗
PubMed2003

[Diagnosis and therapy of early neoplasia in Barrett's esophagus].

There has been a dramatic increase in recent years in the incidence of Barrett's esophagus and the esophageal adenocarcinoma associated with it. Adequate monitoring strategies and improved diagnostic procedures are therefore essential. Alongside conventional video endoscopy with four-quadrant biopsies, many additional diagnostic procedures are now available to improve monitoring. These allow early diagnosis of dysplastic areas and early carcinomas. Endoscopic therapy has gained more and more importance in the treatment of early esophageal neoplasias over the last few years. Localized lesions in the Barrett's segment should be treated by endoscopic resection (ER). Only in patients with not localized or multifocal superficial lesions photodynamic therapy (PDT) should be used. Between the different ER techniques the "suck and cut"-technique with ligation device or cap should be favoured to normal strip biopsy in the esophagus because of the size of the resected specimen and its technical feasibility. ER of high grade intraepithelial neoplasia and mucosal adenocarcinoma in Barrett's esophagus should be considered as the treatment of choice. ER of early neoplasia in Barrett's esophagus is a safe and effective method but should only be performed by experienced endoscopists.

Adenocarcinoma↗
PubMed2002

Scorecard endoscopy: a pilot study to assess basic skills in trainees for upper gastrointestinal endoscopy.

BACKGROUND: The development of training models and structured training courses for endoscopic techniques provides practical experience. To assess individual performance and progress in this training we developed and tested a scorecard system. METHODS: Three test groups were compared: group 1, ten physicians without previous endoscopic experience; group 2, ten students, without endoscopic experience; group 3, a control group of experienced endoscopists. Groups 1 and 2 underwent 1 week of training with a theoretical introduction and practical demonstrations. They were assessed by the scorecard daily by an experienced tutor. The individual scores and learning curves of the two beginner groups were compared with those of the expert group using a biosimulation model was used. RESULTS: Each participant improved significantly during the 1-week course. Mean scores on the first day in groups 1-3 were, respectively, 26.7+/-10.7, 33.4+/-5.3, and 72.0+/-5.8, and on day 6 they were 62.2+/-6.6, 63.4+/-7.6, and 86.6+/-4.3. The difference between group 3 and the other two groups was significant but not that between groups 1 and 2. CONCLUSIONS: Training in endoscopy can be assessed using our training model and our scorecard protocol, which distinguishes between various levels of experience. In physicians beginning in the field of gastrointestinal endoscopy this approach could help to reduce risks to patients, shorten learning curves, and exclude unskilled individuals from further fruitless interventions.

Animals↗
PubMed2002

[Barrett esophagus--esophageal carcinoma: conservative therapy and observation].

Chronic acid reflux is strongly associated with cancer of the esophagogastric junction and the main reason for the development of specialised intestinalised metaplasia in the esophagus (Barrett's esophagus). Endoscopic surveillance, therefore, is mandatory for long-segment Barrett's esophagus as well as short segment Barrett's. Videoendoscopy with four quadrant random biopsies are standard and new diagnostic tools like chromoendoscopy with methylene blue, magnifying endoscopy or fluorescence detection may turn out to be helpful. Differential surveillance strategies according to the recommendations of the American College of Gastroenterology and the Deutschen Gesellschaft für Verdauungs- und Stoffwechselerkrankungen should be performed for medical and cost-efficiency reasons. Local endoscopic therapy of early cancer and high-grade dysplasia in Barrett's esophagus comprises three different methods: endoscopic mucosal resection (EMR), semiselective, athermal photodynamic therapy (PDT) and thermal techniques such as KTP- or Nd:YAG-laser and argon-plasma coagulation. All endoscopic methods have low morbidity and mortality rates compared to esophageal resection and therefore are an attractive alternative treatment option. Endoscopic mucosal resection is the treatment of choice for all localizable and circumscribed lesions, because the resected specimen can be classified with regard to the histopathological grading, complete resection and submucosal involvement, especially in view of patients who are surgical candidates. PDT is the best local treatment option for multifocal, not localizable or large superficial lesions, as large areas can be treated in a single therapeutic session. Thermal procedure are mainly auxiliary methods for the optimization of EMR or PDT. The shortterm and intermediate results of our studies appear to be promising in view of the high complete local remission rates in combination with the low morbidity and mortality.

Barrett Esophagus↗