Grading of dysplasia in Barrett's oesophagus: substantial interobserver variation between general and gastrointestinal pathologists

AIMS

To determine interobserver variation in grading of dysplasia in Barrett's oesophagus (BO) between non-expert general pathologists and expert gastrointestinal pathologists on the one hand and between expert pathologists on the other hand.

METHODS AND RESULTS

In this prospective multicentre study, non-expert and expert pathologists graded biopsy specimens of 920 patients with endoscopic BO, which were blindly reviewed by one member of a panel of expert pathologists (panel experts) and by a second panel expert in case of disagreement on dysplasia grade. Agreement between two of three pathologists was established as the final diagnosis. Analysis was performed by kappa statistics. Due to absence of intestinal metaplasia, 127/920 (14%) patients were excluded. The interobserver agreement for dysplasia [no dysplasia (ND) versus indefinite for dysplasia/low-grade dysplasia (IND/LGD) versus high-grade dysplasia (HGD)/adenocarcinoma (AC)] between non-experts and first panel experts and between initial experts and first panel experts was fair (kappa = 0.24 and kappa = 0.27, respectively), and substantial for differentiation of HGD/AC from ND/IND/LGD (kappa = 0.62 and kappa = 0.58, respectively).

CONCLUSIONS

There was considerable interobserver variability in the interpretation of ND or IND/LGD in BO between non-experts and experts, but also between expert pathologists. This suggests that less subjective markers are needed to determine the risk of developing AC in BO.

Low molecular weight heparin treatment in steroid refractory ulcerative colitis: clinical outcome and influence on mucosal capillary thrombi

BACKGROUND

In ulcerative colitis, a state of hypercoagulation has frequently been observed. Unfractionated heparin has shown beneficial effects as an adjuvant treatment of steroid refractory ulcerative colitis in open trials and in one placebo-controlled trial. Low molecular weight heparin (LMWH) offers advantages in the method of administration, but it has not been evaluated in severe ulcerative colitis. We therefore assessed the tolerability, safety and potential therapeutical effects of LMWH in hospitalized patients with steroid refractory ulcerative colitis.

METHODS

Twenty-five patients with severely active ulcerative colitis were included in an open-labelled trial. All patients had a flare-up of disease under glucocorticosteroid treatment. Nadroparine calcium 5.700 IE anti-Xa/0.6 mL s.c. was self-administered twice daily for 8 weeks. Patients were monitored for possible adverse events, and changes in clinical symptoms and in laboratory, endoscopical and histological results were analysed.

RESULTS

Tolerability and compliance were excellent and no serious adverse events occurred. In 20 of 25 patients, a good clinical and laboratory response was observed. Also, the endoscopic and histological signs of inflammation were found to be significantly improved. However, this was not accompanied by a significant reduction in the number of mucosal microvascular thrombi after 8 weeks of LMWH treatment.

CONCLUSION

LMWH may be a safe adjuvant therapy for patients with active, glucocorticosteroid refractory ulcerative colitis.

Changes in gastric mucosa and luminal environment during acid-suppressive therapy: a review in depth

Acid-suppressive therapy and subsequent changes in gastric mucosa and luminal environment rank highly amongst the investigated issues in gastroenterology over the past two to three decades. Herewith, we present an overview of these intragastric changes, particularly during long-term administration of acid-suppresive medication and concurrent infection with Helicobacter pylori. Current evidence indicates that: i) Long-term acid suppression facilitates the development of fundic ECL cell hyperplasia, especially in the presence of Helicobacter pylori. No neoplastic changes directly attributable to acid suppression have so far been demonstrated in humans. ii) Acid-suppressive therapy increases the risk of enteric infections. iii) Acid-suppressive therapy does not alter fat and mineral bioavailability, but may decrease the absorption of protein-bound vitamin B12. iv) Acid suppression invariably results in intragastric overgrowth of non-Helicobacter pylori bacterial species. The concurrent infection with Helicobacter pylori may promote this bacterial overgrowth and the intragastric formation of N-nitrosamines. v) Acid-suppressive therapy alters the natural course of Helicobacter pylori gastritis, transforming the antral-predominant pattern into a body-predominant pattern, which in turn may progress to body gland atrophy. The pathophysiology of this phenomenon is currently under investigation. vi) In view of the potential adverse effects of acid suppression in the presence of Helicobacter pylori, the screen-and-treat strategy is advocated for Helicobacter pylori in subjects considered for long-term treatment.

Evidence for a bias toward intracellular antigens in the local humoral anti-tumor immune response of a colorectal cancer patient revealed by phage display

Many patients with colorectal carcinoma (CRC) mount a cellular as well as a humoral immune response to the tumor. To investigate the nature and specificity of the humoral immune response in a CRC patient, lymphocytes infiltrating the primary colorectal tumor and lymph nodes draining the tumor were used as antibody variable (V)-gene pools for the construction of phage antibody repertoires. These libraries were first validated by selection on the antigen tetanus toxoid and shown to contain antibodies that were probably derived from both naive and memory B cells. The repertoires were then screened for the presence of antibodies directed to CRC by selection on the cell line CaCo2. For comparison, the same selections were performed with a phage antibody repertoire made from B cells of healthy donors. Striking differences were observed in the panel of specificities selected from these different repertoires: although a large panel of antibodies reactive with patient-derived primary tumors was obtained from the immune repertoires, none of these discriminated between normal colonic epithelium and colon cancer and none were reactive with cell-surface antigens. However, selections using the non-immune library did result in numerous antibodies that recognized cell surface markers on CaCo2. These data suggest a bias in the local humoral immune response in this CRC patient, directed primarily toward intracellular epithelial-cell specific target antigens.

Is type III intestinal metaplasia an obligatory precancerous lesion in intestinal-type gastric carcinoma?

This retrospective study was performed to assess whether type III intestinal metaplasia is an obligatory precancerous lesion of intestinal-type gastric carcinoma and to determine its possible use as a marker of enhanced cancer risk. From 48 consecutive patients with gastric cancer who underwent a gastrectomy over a 3-year period (mean age 72.0 years; 29 M/19 F), at least two sections from antrum, corpus and tumour-surrounding mucosa were obtained for the examination of presence and subtypes of intestinal metaplasia (IM). It was found that 77.1% of the carcinomas were of the intestinal type and 22.9% of the diffuse type. The intestinal-type was more often found in males (P = 0.01); the mean age at diagnosis in this type was higher than in the diffuse cancer group (P = 0.004). There was a high prevalence of total IM in both the intestinal (75.7%) and diffuse group (88.9%). Type I IM was predominant in antrum and corpus of patients from both groups. Type III IM was only found among patients with intestinal-type carcinoma. However, its prevalence was rather low (26.3%). Therefore the absence of this lesion in patients with other risk factors cannot be used as an argument for lowering the degree of surveillance and its presence seems to be sufficient indication for long-term follow-up.

Dynamic urinary graciloplasty in male goats: a study on histology and urethral pressures

The purpose of this study was to investigate the feasibility of dynamic bulbous urinary graciloplasty with respect to graciloplasty histology and urethral pressures. Two adult male goats underwent a pulled-through bulbous urethral graciloplasty with implant of electrodes and a pulse stimulator. Afterwards, a stimulation protocol was applied to have the fatiguable type II fibers replaced by fatigue-resistant type I fibers. Urethral pressure profilometry as well as analysis of histology was performed afterwards and compared with preoperative biopsies and preoperative recorded urethral pressures. Successful conversion from type II into type I muscle fibers was observed; the percentage of type I fibers increased from 29% to 83%. The percentage of connective tissue increased from 8% to 16%. No stricturing of the bulbous urethra was observed. The urethral pressures before stimulation increased from a mean of 107 cm H2O without stimulation, to 187 cm H2O with stimulation for the two goats. After training, the urethral pressure increased from a mean of 85 cm H2O without stimulation, to 118 cm H2O with stimulation. In male goats, successful dynamic urinary graciloplasty at the bulbous urethra is feasible. The achieved muscle fiber conversion guarantees fatigue-resistance, necessary for a continuous sphincteric muscle contraction. The maximal urethral pressures, however, are lower than those without stimulation.

Phage display of cDNA repertoires: the pVI display system and its applications for the selection of immunogenic ligands

The selection of phage displayed cDNA repertoires on an immobilised target has been reported to be an efficient way to rapidly identify interacting partners. To date, however, only a few successful applications have been reported. Here, we present a review of the current status of the display and selection of cDNA libraries using phage. As an example, we report the construction of a set of phage display vectors suitable for cDNA display based on fusion to the minor bacteriophage coat protein 6 (pVI) of filamentous phage. We have evaluated these vectors through the display of the C(H)3 domain of human IgG and of the Escherichia coli alkaline phosphatase (PhoA) gene. Both the C(H)3 domain of IgG and PhoA are shown to be displayed on pVI, and PhoA is also shown to be enzymatically active. We have constructed primary colorectal tumor cDNA repertoires in these vectors and performed selections on both a monoclonal antibody to beta2 microglobulin (beta2M) and polyclonal antibody sera to human IgG. In both cases, relevant ligands were recovered from the phage displayed cDNA repertoire. These vectors may be used for selection of phage displayed cDNA libraries with polyclonal sera from patients. This will allow the identifying antigenic cDNA products in such diseases as cancer, viral/bacterial infections or autoimmune disease. Furthermore, by selections with other specific biomolecules, this display system may aid the identification of interacting partners in functional genomics.

Somatostatin displayed on filamentous phage as a receptor-specific agonist

1. In search of methods to identify bio-active ligands specific for G protein-coupled receptors with seven transmembrane spanning regions, we have developed a filamentous phage-based selection and functional screening method. 2. First, methods for panning peptide phage on cells were established, using the hormone somatostatin as a model. Somatostatin was displayed on the surface of filamentous phage by cloning into phage(mid) vectors and fusion to either pIII or pVIII viral coat proteins. Peptide displaying phage bound to a polyclonal anti-somatostatin serum, and, more importantly, to several somatostatin receptor subtypes (Sst) expressed on transfected CHO-K1 cells, in a pattern which was dependent on the used display method. Binding was competed with somatostatin, with an IC50 in the nanomolar range. The phage were specifically enriched by panning on cells, establishing conditions for cell selections of phage libraries. 3. Binding of somatostatin displaying phage to sst2 on a reporter cell line, in which binding of natural ligand reduces secretion of alkaline phosphatase (via a cyclic AMP responsive element sensitive promoter), proved that the phage particles act as receptor-specific agonists. Less than 100 phage particles per cell were required for this activity, which is approximately 1000 fold less than soluble somatostatin, suggesting that phage binding interferes with normal receptor desensitization and/or recycling. 4. The combination of biopanning of phage libraries on cells with functional screening of phage particles for receptor triggering activity, may be used to select novel, bio-active ligands from phage libraries of random peptides, antibody fragments, or libraries based on the natural receptor ligand.

A comparison of NSP-reticulons with conventional neuroendocrine markers in immunophenotyping of lung cancers

Neuroendocrine-specific protein (NSP)-reticulons are endoplasmic reticulum-associated protein complexes, which have been identified as markers for neuroendocrine differentiation. In this study, the expression of two members of the family of NSP-reticulons, NSP-A and NSP-C, have been investigated in different types of lung cancer and compared with the expression patterns of five conventional neuroendocrine markers, the neural cell adhesion molecule (NCAM), synaptophysin, chromogranin A, Leu-7, and neurofilament proteins. NSP-A and NSP-C antibodies were reactive with most carcinoid tumour and small cell lung carcinoma (SCLC) cases, while atypical carcinoid tumours showed a variable expression. In the total group of neuroendocrine tumours, a high concordance of expression was found between NSP-A and NSP-C, while their expression correlated well with NCAM and synaptophysin positivity. Chromogranin A, Leu-7, and neurofilament proteins were shown to be expressed to a limited extent in these neuroendocrine tumours. In a selected group of non-SCLCs known to exhibit neuroendocrine features, NSP-A expression was detected at much higher frequency than NSP-C. In virtually all NSP-A positive cases, this expression was associated with one or more of the other neuroendocrine markers. NSP-A expression showed a stronger correlation with conventional neuroendocrine markers than NCAM. In detecting neuroendocrine differentiation in non-SCLC, NSP-A is more sensitive than synaptophysin, chromogranin A, Leu-7, and neurofilament proteins. It is concluded that NSP-reticulons are valuable markers in the diagnosis of neuroendocrine differentiation in non-SCLC and should be used in conjunction with NCAM.

Type and number of Ki-ras point mutations relate to stage of human colorectal cancer

Point mutations in the Ki-ras gene belong to the genetic key events in tumorigenesis of colorectal cancer. The type and number of point mutations were detected in specimens from patients with colorectal carcinomas stages as Dukes B and C using single-stranded conformational polymorphism analysis and sequencing. G-A transitions in codon 12 were exclusively found in Dukes B tumors, G-T transversions mainly in Dukes C, and G-C transversions only in Dukes C tumors. Apparently, the G-T and G-C transversions are associated with metastatic behavior of colorectal carcinomas, while G-A transitions are not. In several samples, multiple point mutations could be detected in codon 12, the frequency of multiple mutations increasing with the stage of the tumor.

Ampullary carcinoid and neurofibromatosis: case report and review of the literature

A 49-year-old woman is reported with an ampullary carcinoid and von Recklinghausen's neurofibromatosis, presenting with melaena. On upper GI-endoscopy a tumour of the ampulla of Vater was seen. Histochemical examination revealed a carcinoid tumour. A review of the literature shows that patients with von Recklinghausen's neurofibromatosis are at increased risk for developing tumours of neuroectodermal origin, with the ampulla of Vater as predilection site. Therefore, early diagnostic evaluation, primarily by gastroduodenoscopy, for malignancies in patients with von Recklinghausen's neurofibromatosis and abdominal discomfort is recommended. Surgical removal is the only therapy so far evaluated.

Epithelial-stromal interactions in colon cancer

In this paper investigations concerning the interactions at the interface between tumor cells and tumor stroma are reviewed. As a model for tumor cell-extracellular matrix interaction human colorectal carcinoma cell lines, in vitro and in vivo, in nude mouse xenografts, were chosen. Based on the available data and on a review of the literature the following conclusions can be drawn. Most malignant epithelial neoplasms at the site of tumor cell invasion display defects in the epithelial basement membrane. This is not merely the result of enzymatic dissolution but rather reflects a shift in basement membrane turnover towards degradation. Elsewhere in the same primary tumor or in a metastasis the balance might be shifted more towards basement membrane deposition. The tendency of a tumor to deposit basement membranes reflects the biological potential of the neoplasm. Basement membranes are deposited by stromal cells or by a concerted action of tumor and stromal cells. Differentiation in a carcinoma is modulated by factors in the extracellular matrix. Endocrine differentiation can be induced in vitro by native basement membranes but also by direct contact of the tumor cells with fibroblasts. Basic FGF is one of the extracellular matrix factors with differentiation inducing capacity. Expression of cell adhesion molecules and integrin receptors tends to be down-regulated in carcinoma cells. Alterations in the expression of these proteins might not be constitutive but rather modulated by the direct environment of the tumor cell and might not only include quantitative alterations but also changes in their cell surface distribution, causing or following loss of cell polarity.