T Kratt

Differential quantitative analysis of MHC ligands by mass spectrometry using stable isotope labeling

Currently, no method allows direct and quantitative comparison of MHC-presented peptides in pairs of samples, such as transfected and untransfected, tumorous and normal or infected and uninfected tissues or cell lines. Here we introduce two approaches that use isotopically labeled reagents to quantify by mass spectrometry the ratio of peptides from each source. The first method involves acetylation and is both fast and simple. However, higher peptide recoveries and a finer sensitivity are achieved by the second method, which combines guanidination and nicotinylation, because the charge state of peptides can be maintained. Using differential acetylation, we identified a beta catenin–derived peptide in solid colon carcinoma overpresented on human leucocyte antigen-A (HLA-A)*6801. Guanidination/nicotinylation was applied to keratin 18–transfected cells and resulted in the characterization of the peptide RLASYLDRV (HLA-A*0201), exclusively presented on the transfectant. Thus, we demonstrate methods that enable a pairwise quantitative comparison leading to the identification of overpresented MHC ligands.

Laparoscopic-assisted transgastric cholecystectomy and secure endoscopic closure of the transgastric defect in a survival porcine model.

BACKGROUND AND STUDY AIMS Natural orifice transluminal endoscopic surgery holds promise for surgical interventions. Before the feasibility of this technique can be established, however, secure sealing of the transluminal access needs to be thoroughly investigated. PATIENTS AND METHODS Following antibiotic prophylaxis and gastric disinfection, nine pigs underwent transgastric cholecystectomy by means of a flexible endoscope with the aid of a transabdominal 5-mm trocar. The gastric wall was punctured and dilated. The gallbladder was retracted with a laparoscopic grasper. The cystic duct and artery were dissected with a flexible monopolar ball electrode. The cystic duct was interrupted with flexible scissors between endoclips. Cholecystectomy was completed and the gallbladder was retrieved through the stomach. The gastric defect was closed using a single modified over-the-scope clip (OTSC) (Ovesco, Tübingen, Germany) and grasping the serosal and muscle layer of the gastric wall. The animals were sacrificed 4 weeks later. RESULTS Laparoscopic-assisted transgastric cholecystectomy was successful in all cases without significant perioperative complications. All animals survived without postoperative complications. The mean operating time was 128 minutes (range, 85 - 205 minutes). The gastric defect closure resulted in inversion of the gastric wall layers within an average time of 6.8 +/- 5 minutes. At 4 weeks postoperative, only minimal thin adhesions were observed in the right hypochondrium. CONCLUSIONS We found gastric closure using the OTSC to be a reliable tool for closing the transgastric access. Laparoscopic-assisted transgastric cholecystectomy by means of a flexible endoscope was technically feasible, but remains a demanding procedure.

CD8+ T-cell response against MUC1-derived peptides in gastrointestinal cancer survivors

The tumor-associated antigens CEA, MUC1 and Her2/neu are broadly expressed in gastrointestinal tumors, and are attractive candidates for targeting by T-cell-based immunotherapy. However, little is known about the natural cytotoxic T-cell response of patients suffering from colorectal or gastric carcinoma against these three as well as other antigens. Using a quantitative reverse transcription-polymerase chain reaction-based assay for IFN-γ, we analyzed the CD8+ T-cell repertoire present in the blood of HLA-A2+ gastrointestinal tumor survivors against five known epitopes derived from CEA, MUC1 and Her2/neu. The results show that most of the patients (16 from 22 tested) have detectable, peripheral CD8+ T cells directed against at least one of these three proteins. Interestingly, the majority of these patients reacts to the two MUC1-derived HLA-A*0201 epitopes tested (14 from 16), demonstrating that this protein represents one dominant target for CD8+ T cells in gastrointestinal cancer.

Indication for 'Over the scope' (OTS)-clip vs. covered self-expanding metal stent (cSEMS) is unequal in upper gastrointestinal leakage: results from a retrospective head-to-head comparison.

Background Intestinal perforation or leakage increases morbidity and mortality of surgical and endoscopic interventions. We identified criteria for use of full-covered, extractable self-expanding metal stents (cSEMS) vs. ‘Over the scope’-clips (OTSC) for leak closure. Methods Patients who underwent endoscopic treatment for postoperative leakage, endoscopic perforation, or spontaneous rupture of the upper gastrointestinal tract between 2006 and 2013 were identified at four tertiary endoscopic centers. Technical success, outcome (e.g. duration of hospitalization, in-hospital mortality), and complications were assessed and analyzed with respect to etiology, size and location of leakage. Results Of 106 patients (male: 75 (71%), female: 31 (29%); age (mean ± SD): 62.5 ± 1.3 years, 72 (69%) were treated by cSEMS and 34 (31%) by OTSC. For cSEMS vs. OTSC, mean treatment duration was 41.1 vs. 25 days, p<0.001, leakage size 10 (1-50) vs. 5 (1-30) mm (median (range)), and complications were observed in 68% vs. 8.8%, p<0.001, respectively. Clinical success for primary interventional treatment was observed in 29/72 (40%) vs. 24/34 (70%, p = 0.006), and clinical success at the end of follow-up was 46/72 (64%) vs. 29/34 (85%) for patients treated by cSEMS vs. OTSC; p = 0.04. Conclusion OTSC is preferred in small-sized lesions and in perforation caused by endoscopic interventions, cSEMS in patients with concomitant local infection or abscess. cSEMS is associated with a higher frequency of complications. Therefore, OTSC might be preferred if technically feasible. Indication criteria for cSEMS vs. OTSC vary and might impede design of randomized studies.

Surgery of Colorectal Carcinoma in Patients Aged over 80

Background: The incidence of colorectal carcinoma increases rapidly in aged patients. We investigated retrospectively the differences in treatment relative to the patients’ age. Patients and Methods: A total of 394 patients with colorectal carcinoma (group I: ≥80 years, n = 197; group II: 60–79 years, n = 197) were analyzed in an average period of 4 years in relation to surgery, comorbidities, postoperative morbidity, mortality, survival and recurrence. Results: Patients ≥80 years had a significantly higher rate of comorbid conditions (p = 0.04; cardiovascular, p = 0.01; diabetes mellitus, p < 0.05) and more carcinomas in the sigmoid/rectum (72% vs. 67%; p < 0.05). Tumor stage, R0 resection rate, and overall complication rate were not influenced by age. The 30-day mortality rate was significantly higher in group I (12% vs. 3%; p = 0.02). Emergency surgical procedures were required significantly more often in group I (14%) than in group II (5%; p = 0.003). The 5-year survival rate among patients in group I was 30.1% compared to 50.5% among patients in group II (p < 0.0001). Conclusions: Elderly patients have a higher rate of comorbidity and a higher postoperative 30-day mortality rate. Tumor stage, R0 resection rate, and overall postoperative complication rate do not appear to be influenced by age. The higher rate of emergency operations on patients ≥80 years is associated with the higher 30day mortality. Even in patients aged ≥80 years, attention should focus on the long-term oncological results, after appropriate assessment of the preoperative risk.

Transpapillary retrieval of a proximally migrated stent using a three-prong polyp retrieval device in a 2-years-old girl.

Endoscopic retrieval of proximally migrated biliary stents is sometimes challenging. We report on the successful use of a three-prong colon polyp retrieval device in a two year old child.

After Intestinal Transplantation Kidney Function Is Impaired by Downregulation of Epithelial Ion Transporters in the Ileum

BACKGROUND Intestinal transplantation is a treatment option for intestinal failure. Although nephrotoxic medication after transplantation is a major cause for posttransplant renal insufficiency, it remains unclear why kidney dysfunction is particularly frequent after intestinal transplantation. METHODS This study analyzed messenger RNA expression of NHE3, DRA, and CFTR in 404 biopsies obtained between day 2 and 1508 from the terminal ileum of 10 adult intestinal transplant recipients. RESULTS The time courses of immunosuppression and glomerular filtration rate were correlated. In the first posttransplant year, expression of NHE3 and DRA, which mediate NaCl absorption, was diminished to a greater degree than that of CFTR, which mediates chloride secretion. Reduced NHE3 and DRA expression was associated with high tacrolimus trough levels. Titration of tacrolimus to low levels by year 2 was paralleled by partially restored NHE3 and DRA expression. In cell culture experiments, similar effects of tacrolimus on transporter expression were detected. In patients, both reduced tacrolimus levels and recovery of NHE3 and DRA expression were associated with stabilization of renal function. CONCLUSIONS Our data strongly suggest that tacrolimus impairs absorption of NaCl and water from the transplanted ileum, leading to volume depletion and impaired renal function. This may be reversible by reduction of tacrolimus to lower levels without increased rates of rejection or chronic graft failure.

Therapeutic Management of Submucosal Gastric Tumors: A Series of Six Cases with Ectopic Pancreas in the Stomach and Description of a Novel Endoscopic Full-Thickness Resection Technique of the Gastric Wall

Ectopic pancreas is a benign congenital abnormality, defined as pancreatic tissue that lacks anatomic or vascular continuity to the pancreas. An incidence of 0.55%-13% has been described in autopsy studies. Ectopic pancreas is most commonly found in the upper GI-Tract.

OTSC-assistierte Resektion eines neuroendokrinen Tumors im Duodenum : ein Fallbericht

The over the scope clip (OTSC) is mainly used for closure of gastrointestinal endoluminal defects and treatment of gastrointestinal bleeding. Its use for resection of subepithelial tumors or full-thickness resection is still under investigation. Duodenal neuroendocrine tumors (NET) are rare neoplasms. Endoscopic resection is appropriate up to a size of 20  mm, however positive deep margins are a frequent challenge in these subepithelial tumors. We report on a 60-year-old male patient who had undergone endoscopic mucosal resection with R1 deep margins of a NET (G1) in the duodenal bulb. To avoid local surgical resection in this multimorbid patient, we performed OTSC-assisted deep resection. Complete resection (R0) was achieved, and no complications occurred. Our report suggests that OTSC-assisted resection of subepithelial tumors is a possible and safe option, especially for patients and in locations with a high perioperative risk.

Is There Any Additional Benefit of Contrast-Enhanced CT as Part of Routine PET/CT Protocols for the Differentiation of Suspicious Incidental Gastrointestinal 2-Deoxy-18F-FDG Uptake?

Objective Suspicious incidental gastrointestinal FDG uptake during positron-emission tomography/computed tomography (PET/CT) examinations can be caused by different diseases, including malignancies. However, differentiation with PET alone is difficult. The aim of this study was to investigate the potential of PET alone, contrast-enhanced CT (ceCT), and low-dose CT (ldCT) in routine PET/CT protocols for differentiation of incidental gastrointestinal lesions. Materials and Methods Sixty patients with incidental gastrointestinal lesions who underwent a routine PET/CT protocol with ldCT and ceCT were retrospectively analysed. The PET lesions were evaluated regarding their FDG uptake patterns and the standard uptake value. The anatomical correlates in both CT protocols were compared in regard to the correct lesion classification with the reference standard endoscopy. Results Sixty-two lesions were found in 60 patients (17 malignant, 10 premalignant, 5 benign, 13 inflammatory, 17 physiological). The differentiation of the FDG uptake patterns did not enable reliable lesion classification. The positive predictive value for pathology was 0.81 for ceCT in PET/CT and 0.70 for ldCT. Malignancies were detected in 100% of the patients by ceCT vs. 29.4% by ldCT. The false negative rate of ceCT for all pathologies was 31.1%, vs. 68.9% for ldCT. False positive results (17/62) could not be excluded sufficiently by either CT protocol. Conclusion PET/ceCT protocols provide additional benefit especially in detecting gastrointestinal malignancies as a cause of suspicious incidental gastrointestinal FDG uptake. However, since follow-up endoscopy cannot be forgone due to the considerable false negative rate even with ceCT, the addition of ceCT to a routine PET/ldCT protocol cannot be recommended for this purpose.