Biomedical subjects

Hartmut Schäfer

Publications and source records attributed to Hartmut Schäfer.

3 recordsLinked to original sources

PubMed2005

Giant adenomas of the rectum: complete resection by transanal endoscopic microsurgery (TEM).

BACKGROUND: Large sessile adenomas of the rectum, with a diameter greater than 5 cm, have a high risk to undergo malignant transformation. Transanal endoscopic microsurgery (TEM) offers an alternative operation method to low-anterior rectum resection in this potentially benign tumor situation. PATIENTS: We retrospectively investigated patients with giant adenomas of the rectum (>5 cm) who were treated by TEM over the last 10 years. A total of 33 patients met the criteria and were analyzed for postoperative complications, histology, and incidence of occult adenocarcinoma; residual tumor status; and tumor recurrence. RESULTS: Partial suture-line insufficiency (n=5, 15%) was the major postoperative complication, but could be managed conservatively in four cases. The residual adenoma status was 18% (n=6), especially in patients with tumors sizes more than 30 cm2. In case of adenoma recurrence (n=4, 12%), a conventional transanal excision (Parks) was applicable, as these tumors were mostly located within the suture-line region of the lower rectum. Incidentally, five carcinomas were found in the specimens. In case of advanced tumors (1xpT2, 1xpT3), anterior rectum resection was carried out, whereas for the early tumors (2xpT1 low risk, 1x1 pTis), no further therapy was added. All patients (adenomas and carcinomas, n=33) were without recurrence during follow-up. CONCLUSION: TEM is an alternative method for the resection of large benign rectal tumors located in the mid- and upper third of the rectum. The main postoperative complication is suture-line insufficiency, which generally heals by conservative treatment.

Adenoma↗

PubMed2005

The molecular signature of normal squamous esophageal epithelium identifies the presence of a field effect and can discriminate between patients with Barrett's esophagus and patients with Barrett's-associated adenocarcinoma.

BACKGROUND AND AIM: Genetic alterations in the normal tissues surrounding various cancers have been described, but a comprehensive analysis of this carcinogenic field effect in Barrett's-associated adenocarcinoma of the esophagus disease has not been reported. The aim of this study was to analyze the gene expression profile of a panel of highly selected genes in the normal squamous esophagus epihelium of patients with Barrett's esophagus, patients with Barrett's-associated adenocarcinoma, and a healthy control group to define the existence of a carcinogenic field effect, and to investigate the clinical importance of such a field effect in the management of Barrett's disease. METHODS: Forty-nine histologic normal squamous esophageal epithelia collected from 19 patients with Barrett's esophagus, 20 patients with Barrett's-associated esophageal adenocarcinoma, and a healthy control group of 10 patients were studied. A quantitative real-time reverse transcription-PCR method (TaqMan) was used to measure the expression of a panel of genes with known associations with gastrointestinal carcinogenesis. RESULTS: A widespread carcinogenic field effect was detected for more than 50% of the genes analyzed including Bax, BFT, CDX2, COX2, DAPK, DNMT1, GSTP1, RARalpha, RARgamma, RXRalpha, RXRbeta, SPARC, TSPAN, and VEGF. Based on the expression signature of the normal appearing squamous esophagus, a linear discriminant analysis was able to distinguish between the three groups of patients with an error rate of 0%. CONCLUSION: This study provides the first comprehensive investigation of a carcinogenic field effect in Barrett's esophagus disease. Based on the gene expression signature of the normal esophagus, patients could be correctly characterized according to their pathologic classification by applying a linear discriminant analysis. Our results provide evidence that a molecular classification might have clinical importance for the diagnosis and treatment of patients with Barrett's esophagus disease.

Adenocarcinoma↗

PubMed2003

Inverse methods in two-dimensional NMR spectral analysis.

Solid-state NMR is a valuable technique for the study of disordered materials. Analysis of such spectra usually involves solution of so-called ill-posed inverse problems. Here we present a strategy for the analysis of two-parameter two-dimensional NMR problems and test it on 2D DECODER and DOQSY experiments. Using Monte Carlo tests, constraints are determined for the resolution and accuracy of the analysis for both experiments. The methods are finally applied to spectra of spider dragline silk, a heterogeneous solid fibrous protein.

Animals↗