M. Kruschewski

Dietary resistant starch and chronic inflammatory bowel diseases.

Abstract These studies were performed to test the benefit of resistant starch on ulcerative colitis via prebiotic and butyrate effects. Butyrate, propionate, and acetate are produced in the colon of mammals as a result of microbial fermentation of resistant starch and other dietary fibers. Butyrate plays an important role in the colonic mucosal growth and epithelial proliferation. A reduction in the colonic butyrate level induces chronic mucosal atrophy. Short-chain fatty acid enemas increase mucosal generation, crypt length, and DNA content of the colonocytes. They also ameliorate symptoms of ulcerative colitis in human patients and rats injected with trinitrobenzene sulfonic acid (TNBS). Butyrate, and also to a lesser degree propionate, are substrates for the aerobic energy metabolism, and trophic factors of the colonocytes. Adverse butyrate effects occur in normal and neoplastic colonic cells. In normal cells, butyrate induces proliferation at the crypt base, while inhibiting proliferation at the crypt surface. In neoplastic cells, butyrate inhibits DNA synthesis and arrests cell growth in the G1 phase of the cell cycle. The improvement of the TNBS-induced colonic inflammation occurred earlier in the resistant starch (RS)-fed rats than in the RS-free group. This benefit coincided with activation of colonic epithelial cell proliferation and the subsequent restoration of apoptosis. The noncollagenous basement membrane protein laminin was regenerated initially in the RS-fed group, demonstrating what could be a considered lower damage to the intestinal barrier function. The calculation of intestinal short-chain fatty acid absorption confirmed this conclusion. The uptake of short-chain fatty acids in the colon is strongly inhibited in the RS-free group, but only slightly reduced in the animals fed with RS. Additionally, RS enhanced the growth of intestinal bacteria assumed to promote health. Further studies involving patients suffering from ulcerative colitis are necessary to determine the importance of RS in the therapy of a number of intestinal diseases and the maintenance of health.

Does glutamine reduce bacterial translocation? A study in two animal models with impaired gut barrier.

Abstract Failure of intestinal barrier function and subsequent translocation of bacteria from the gut are believed to play a decisive role in the development of systemic septic complications, for example, following major trauma or major abdominal surgery. This study evaluated: (a) the effect of glutamine on colonic microcirculation and electrophysiological parameters reflecting gut barrier function, (b) the translocation of live bacteria to extraintestinal organs, and (c) disease outcome in two animal models with impaired gut barrier function. Severe acute pancreatitis or colitis was induced in rats randomized for therapy with or without glutamine (0.5 g/kg daily). After 48 h one animal group was prepared for intravital microscopy of colonic capillary blood flow and electrophysiological measurement of gut permeability; another was killed after 96 h for histological and microbiological examination. In animals with pancreatitis, glutamine (Gln) supplementation significantly improved gut permeability, i.e., Gln increased colonic transmucosal resistance from 67±7 to 92±3 Ω/cm2 and decreased mannitol flux through the epithelium by 53%. Capillary blood flow in the colonic mucosa was improved by 25%. The prevalence of pancreatic infections was reduced from 86% in animals on standard parenteral nutrition to 33% in animals given the Gln-enriched diet (P<0.05); mortality decreased by 32%. In colitis, Gln had no significant effect on these parameters except for improving colonic capillary blood flow in colon segments not adjacent to the major injury site. Glutamine supplementation improves colonic capillary blood flow, stabilizes gut permeability, and reduces secondary pancreatic infections and mortality in severe rodent pancreatitis, but it is not helpful in colitis. This confirms previous reports that glutamine stabilizes gut barrier function only in certain diseases. Our experimental data strongly suggest that acute pancreatitis (rather than colitis) is one of the diseases with gut barrier dysfunction in which glutamine substitution may be helpful to reduce bacterial translocation and should therefore be tested in a controlled clinical trial.

Changes of Colonic Mucosal Microcirculation and Histology in Two Colitis Models: An Experimental Study Using Intravital Microscopy and a New Histological Scoring System

This study investigated capillary blood flow (CBF) and pathomorphological alterations in the mucosa of different bowel segments at different times after disease onset in rats with colitis induced by either trinitrobenzensulfonic acid (TNBS) or mitomycin-C. CBF was determined by intravital microscopy using fluorescein-labeled erythrocytes. The histological degree of inflammation was assessed by a new scoring system. Severe acute histological changes were found in the distal colon 24 hr after induction of TNBS colitis (score: 8.9 ± 1.0). CBF was increased (2.9 ± 0.05 vs. 2.6 ± 0.04 nl/min in healthy controls). The histological alterations persisted until day 3 (8.5 ± 0.9) when CBF significantly decreased (1.8 ± 0.05 nl/min). After 15 days, moderate acute inflammation was still detectable histologically (5.4 ± 1.3), but CBF had returned to normal values. In mitomycin-C colitis, changes developed mainly in the proximal colon: After three days, there was mild inflammation (2.8 ± 1.2) with normal CBF (2.5 ± 0.1 nl/min). After seven days, the inflammation had increased (4.8 ± 1.1), while CBF had decreased (1.5 ± 0.06 nl/min). These changes persisted for six weeks (5.3 ± 0.7; 1.2 ± 0.05 nl/min). These data suggest that disturbed colonic microcirculation may play an important role in the pathogenesis of inflammatory bowel disease regardless of the histopathomorphological alterations.

Does microcirculation play a role in the pathogenesis of inflammatory bowel diseases? Answers from intravital microscopic studies in animal models

Abstract The potential role of intestinal microcirculation for the development of inflammatory bowel diseases (IBD) has not been systematically investigated, mainly because of methodological problems. Using a well-established rodent model of IBD and intravital microscopy, the present study investigated whether (and when) gut microcirculation is disturbed in IBD, and whether microcirculatory disorders contribute to histological and functional alterations in the development of IBD. Colitis was induced by rectal injection of trinitrobenzene sulfonic acid. After 1, 3, and 15 days rats were laparotomized for intravital microscopic determination of mucosal colonic blood flow. In a second series it was examined whether enhancing colonic capillary blood flow by hemodilution therapy stabilizes colonic wall resistance and other electrophysiological parameters of gut permeability. Additional measurements involved hemodynamic monitoring and histological examinations. Colonic capillary blood flow was significantly decreased 3 days after colitis induction (1.8±0.05 vs. 2.6±0.04 nl/min in healthy control animals) when histology revealed signs of acute inflammation, and normal values after 15 days (2.4±0.06 nl/min) when chronic histological changes were evident. Hemodilution therapy enhanced colonic capillary blood flow in the initial stage (2.1±0.02 vs. 1.6±0.02 nl/min in saline-treated animals with trinitrobenzene sulfonic acid colitis) and improved gut resistance and electronic chlorid secretion (73±15 vs. 33±8 μA cm2). Histological alterations were not significantly attenuated. Impaired colonic capillary blood flow in the initial stage of experimental colitis and improved mucosal microcirculation with stabilized gut permeability suggests that the early microcirculatory disturbances precede chronic histological changes and influence functional alterations in the course of the disease. Research should be continued in this field because important mechanisms in the pathogenesis of IBD and potentially therapeutic (vasoactive) substances may otherwise be overlooked.

The prognostic significance of tumor vascularization in patients with localized colorectal cancer

Abstract Angiogenesis is essential for tumor growth and metastasis, and vascular density is known as an independent prognostic factor in several tumor entities. We studied the prognostic relevance of vascular density in colorectal cancer, examining 146 patients treated surgically for cure. Tumor sections were immunostained with JC70, an endothelial cell marker. Microvessel quantification used light microscopy. The slides were scanned at a low magnification, and individual microvessel counts were made on a ×200 field in the area of the most dense neovascularization. Vascular density was found to be 75±27/visual field and to be independent of age, sex, pT and pN categories, tumor recurrence, and overall survival. Overall survival in the subgroup of patients with tumor recurrence was significantly shorter with tumors of greater vessel density (>75) than in those of less vessel density (<75). Multivariate analysis showed microvessel count to be an independent prognostic factor for the overall survival rate of patients with tumor recurrence; among these patients there was also a significant difference in the relapse-free survival rates between the hypovascular and the hypervascular groups. Our findings suggest that the microvessel density of the primary tumor determines the speed of tumor recurrence after metastatic disease has been triggered by other, unknown mechanisms. Although tumor vascularization can be linked to the aggressiveness of colorectal cancer, it has no value as a new prognostic marker in clinical practice.

Is reduced expression of mismatch repair genes MLH1 and MSH2 in patients with sporadic colorectal cancer related to their prognosis

The majority of mutations in hereditary nonpolyposis colon carcinoma (HNPCC) patients affect the mismatch-repair genes (MMRG) MLH1 and MSH2. In addition, mutations of these genes were found in about 15% of sporadic colorectal carcinomas which appear to be related to microsatellite instability (MSI). However, mutations in MMRG were not found in all MSI-positive carcinomas, but MMRG mutations may be relevant for the assessment of tumor characteristics and patients’ prognosis. Therefore, we investigated the relationship between expression of MMRG, tumor biology and patients’ survival. In 127 patients with sporadic colorectal carcinomas and a minimum of 5 years follow-up after curative surgery immunohistochemical detection of MLH1 and MSH2 was analyzed semiquantitatively. Lost expression of MLH1 has been found in tumor specimens from 10 patients, whereas MSH2 expression was missing in 5 patients. This reduced expression did not correlate with tumor stage, lymph node involvement, grading or tumor invasion into blood vessels. However, a significant correlation was found for lymphovascular invasion (P=0.02) and localization within the colorectum (P=0.003) in MLH1-negative carcinomas. In addition, although there was a clear tendency for longer overall survival (72 vs. 63 months) for patients with MLH1-negative carcinomas, significant differences for overall and recurrence-free survival were not seen. In conclusion of our results and a critical review of literature, the prognostic importance of the MMR genes in sporadic colorectal carcinomas remains controversial.

Radical resection in obstructing colorectal carcinomas

Abstract Emergency resections of obstructing colorectal carcinomas usually involve only limited rather than radical lymphadenectomy, which may contribute to the poor long-term survival of these patients. Thirty patients with ileus due to colorectal cancer have been included in a prospective follow-up study since January 1995. Seventeen of these underwent potentially curative resections with radical locoregional lymphadenectomy according to current standards of elective oncological surgery; 2 had radical right and 15 had radical left hemicolectomies. Postoperative morbidity was 18%. An 89-year-old patient died following postoperative bleeding from the colostomy site. During the same period, 13 patients with a metastasizing colorectal carcinoma underwent palliative emergency surgery with a resection rate of only 38%. Morbidity and mortality were 69% and 46%, respectively. These results suggest that emergency radical resections can be safely performed in the majority of patients with obstructing colorectal cancer without increasing the complication rate.

The Prognostic Impact of p53 Expression on Sporadic Colorectal Cancer Is Dependent on p21 Status

The prognostic value of p53 and p21 expression in colorectal cancer is still under debate. We hypothesize that the prognostic impact of p53 expression is dependent on p21 status. The expression of p53 and p21 was immunohistochemically investigated in a prospective cohort of 116 patients with UICC stage II and III sporadic colorectal cancer. The results were correlated with overall and recurrence-free survival. The mean observation period was 51.8 ± 2.5 months. Expression of p53 was observed in 72 tumors (63%). Overall survival was significantly better in patients with p53-positive carcinomas than in those without p53 expression (p = 0.048). No differences were found in recurrence-free survival (p = 0.161). The p53+/p21− combination was seen in 68% (n = 49), the p53+/p21+ combination in 32% (n = 23). Patients with p53+/p21− carcinomas had significantly better overall and recurrence-free survival than those with p53+/p21+ (p < 0.0001 resp. p = 0.003). Our data suggest that the prognostic impact of p53 expression on sporadic colorectal cancer is dependent on p21 status.

The insertion of the lesser and greater gastric omenta and its significance for the T classification of gastric carcinomas (UICC)

The problem of T classification of proximal gastric carcinomas is becoming increasingly important due to a rise in the incidence of these tumors. The aim of this study was to examine the gastric insertion of the lesser and greater omenta and its role in the T classification of gastric carcinomas. The stomach and greater and lesser omenta were removed from 76 fixed cadavers and 12 measurements each were done in defined localizations. The lesser omentum extended to the gastric wall in 98% of the cases. This junction as well as the omental thickness and thus the retroperitoneal part are especially pronounced in the cardiac region. According to the current UICC classification, even advanced tumors extending into the gastric wall can be classified T2 as long as they do not penetrate the visceral peritoneum. This results in « understaging » and a seemingly poorer prognosis for cardiac carcinomas. Our study results support the recommendation of Hermanek and Wittekind [5] to subdivide the T2 stage of gastric carcinomas on the basis of infiltration depth.

Nachweis signifikanter Störungen der Darmmikrozirkulation bei verschiedenen Colitis-Modellen

Gefasveranderungen im Bereich der Darmwand, sowohl beim M. Crohn als auch bei der Colitis ulcerosa, sind wiederholt beschrieben worden [1, 3]. Allgemein wird ihnen eine im Rahmen des Entzundungsgeschehens ablaufende (sekundare) Bedeutung zugeschrieben. Wakefield et al. [7] beschrieben allerdings als fruhe Alteration eine fokale Arteriitis und postulierten ein multifokales Infarktgeschehen auf dem Boden einer chronischen Vaskulitis in der Pathogenese des M. Crohn. Vor allem wegen fehlender methodischer Voraussetzungen konnte die Bedeutung von Storungen der Mikrozirkulation des Darmes fur die Entstehung und Progression der chronisch entzundlichen Darmerkrankungen bisher nicht systematisch untersucht werden. In der vorliegenden Studie wurden erstmals mittels Intravitalmikroskopie funktionelle Untersuchungen der Mikrozirkulation der Dickdarmschleimhaut bei zwei Colitis-Modellen zu verschiedenen Zeitpunkten durchgefuhrt. Die Befunde im Bereich der Mikrozirkulation wurden mit den pathomorphologischen Veranderungen korreliert.