[20-year old woman with diarrhea of unknown etiology]

We report on a 20-year old woman who suffered from watery diarrhea. The results of the histology and the serology as well as clinical symptoms lead us to the diagnosis of sprue. Under specific gluten-free diet the diarrhea frequency was reduced. After a few weeks the patient returned to hospital again because of watery diarrhea. Histological examination of duodenal biopsy specimen showed a protracted infectious duodenitis and a secondary villous flattening of the small bowel. This diagnosis was a life-threatening illness that needed antibiotic treatment. These patients receive parenteral nutrition as long as the villous have not been recovered from the flattening. Additionally octreotid can be given to reduce the frequency of the diarrhea.

[Chronic diarrhea in adults: diagnostic strategies]

The presence of chronic diarrhea requires a prompt diagnostic strategy in order to avoid risks of malnutrition and electrolytic disturbances. Two different clinical situations, i.e. collagen colitis and secretory diarrhea, exemplify the diagnostic evaluation of a single symptom. This non exhaustive review should lead to a diagnostic strategy of chronic diarrhea.

Blind loop syndrome: multiple ileal ulcers following side-to-side anastomosis

A 59 yr old woman who had multiple ileal ulcers following side-to-side anastomosis without bowel resection is reported. She had a surgical history of adhesive ileus 15 yrs earlier, and was admitted with a complaint of lower abdominal pain. A barium meal study showed a stagnant and dilated distal ileum. At laparotomy, a previously performed side-to-side ileal anastomosis was encountered, and a markedly dilated bypassed loop was recognized. The affected intestine was resected revealing multiple longitudinal ulcers and small shallow ulcers mostly located on the mesenteric side. This feature is similar to that of ischemic enteritis. This case further supports the fact that when side-to-side anastomosis is performed as a bypass operation, multiple ulcers may develop in a bypassed loop after a long period of time.

[Blind loop of the large intestine--bypass enteropathy or diversion colitis?]

Investigating three patients with longstanding diarrhoea, severe abdominal bloating and cramps revealed an exclusion of the right hemicolon in all patients and additionally of the terminal ileum in one of them. The anastomosis of the ileo-colic bypass, performed decades ago due to complicated appendicitis, was stenotic in two of them. Because a classical blind-loop-syndrome could not be proven, the functional disorder is described as a clinical entity characterized by signs of bypass-enteropathy and diversion-colitis. The importance of the radiological examination for diagnosis and therapy-planing is emphasized, because endoscopically and histologically Crohn's disease might be suspected. The surgical reintegration of the bowel into the orthograde continuity of the intestinal tract is recommended as the causative treatment. Symptoms disappear completely and patients win normal health even after some decades, because the morphological signs of inflammation are reversible and bowel function is not lost during the exclusion.

Tight junction regulation during impaired ion transport in blind loops of rat jejunum

Epithelial cell tight junction structure in self-filling blind loops of rat jejunum, a model for blind loop syndrome in humans, was analyzed morphometrically along the crypt-villus axis. In control jejunum, the number of strands and junctional depth, including meshwork depth, decreased from crypt to villus tip. In the blind loop, aberrant strands appeared below the meshwork, particularly in crypt cells. Consequently, total junctional depth was greater than in controls. Furthermore, strand number and junctional meshwork depth were increased in blind loops at the villus tip. It is that site along the crypt-villus axis which showed the most shallow junction in control jejunum. This structural change is paralleled by a three-fold increase in epithelial resistance as previously measured by alternating current impedance analysis. Relative Na over Cl permeability (PNa:Cl) was obtained from dilution potential measurements. PNa:Cl was 1.50:1 in control jejunum and 1.35:1 in the blind loop (n.s.). Considering the cation selectivity of the tight junction, the increase in epithelial resistance in blind loops cannot be attributed to a collapse of the lateral intercellular space but is due to changes in tight junctional permeability resulting from structural alteration. The blind loop syndrome represents a further example of diminished epithelial ion transport and concomitant decrease in tight junction permeability, thus supporting the general concept of regulation of the tight junction in response to active transport activity.

Multiple malignant lymphoma within an ileal blind loop--report of a case

A 55-year-old woman presented to our hospital with abdominal fullness and edema of both legs. She had undergone a bypass operation by an ileotransversostomy for adhesive ileus following a drainage operation for acute appendicitis 35 years previously. We diagnosed the patient as having blind loop syndrome as a consequence of the side-to-side ileotransversostomy, and performed a right hemicolectomy and intestinal resection. The resected specimen of dilated ileal blind loop contained 15 crater-like lesions, proven histologically to be nodular proliferation of atypical lymphocytes. Lymph follicles had also proliferated in the mucosa of the blind loop and the histologically confirmed diagnosis of non-Hodgkins lymphoma of the diffuse medium-sized cell type was thus made. The etiology of such tumors is probably related to the alteration in intestinal environment caused by conditions such as fecal stasis, bacterial overgrowth, and bacterial toxins in the blind loop.

Adaptation of the jejunal mucosa in the experimental blind loop syndrome: changes in paracellular conductance and tight junction structure

Self-filling blind loops of rat jejunum exhibit hyperregenerative transformation of the mucosa. We used this experimental model to characterise mechanisms, which may occur under similar conditions in man (stagnant loop syndrome). Epithelial and subepithelial resistance were measured in the Ussing-chamber by voltage divider ratio measurements after positioning a microelectrode between epithelium and subepithelial tissue layers. In the blind loop, epithelial resistance increased from 8 +/- 1 to 23 +/- 1 omega cm2 and subepithelial resistance from 39 +/- 4 to 86 +/- 8 omega cm2 as compared with control jejunum. The increase in the subepithelial resistance was paralleled anatomically by an increase in the thickness of the subepithelial tissue layers from 63 +/- 4 microns to 177 +/- 19 microns. Ultrastructural analysis of the tight junction area by freeze fracture electron microscopy revealed an increase in the total junctional 'depth' in the crypts from 243 +/- 9 nm in control jejunum to 396 +/- 17 nm in the blind loop, while the number of horizontally oriented 'strands' remained unchanged. Villus tight junctions did not differ between blind loop and control. We interpret the alterations in the self-filling blind loop as an adaptive response of the epithelium which reduces backleakage of already absorbed electrolytes across the tight junction into the intestinal lumen. This mechanism is suitable to support the intestine in maintaining body electrolyte and water contents during cellular electrolyte malabsorption.

Pathogenesis of the mucosal hyperplasia in self-filling blind loops of rat jejunum: a morphometric study in germ free animals

Bacterial overgrowth and high intraluminal concentrations of deconjugated bile acids are thought to be responsible for mucosal hyperplasia in self-filling blind loops of rat jejunum. To investigate this hypothesis further we have assessed the three dimensional architecture of these loops created in germ free animals without or with di- or mono-association of different bacterial species. It was found that mucosal hyperplasia develops in the absence of any bacterial contamination and that bacterial association does not lead to a more pronounced mucosal proliferation. This implies that other mechanisms provoke this morphological phenomenon. Increased bulk contents in these loops or immunological events are probably the most likely explanation.

Component quantitation of rat ileum

Precise and accurate light microscopic morphometric analyses of biological tissue can be achieved utilizing component quantitative techniques. Component quantitation refers to measurements of the relative volumes of components in tissue sections. Such an assessment is predicated upon the mathematically verifiable assumption that direct quantitative relationships exist between an aggregate of profiles of a component contained per unit area in multiple sections and an aggregate of profiles contained per unit volume. A linear scanning device (micrometer component quantitator) was initially employed for quantitative analyses of pancreas. This quantitative technique has subsequently been applied to normal rat ileum conventionally processed for light microscopy, and the requisite sampling parameters have been defined. An identical technique was then applied to physiologically manipulated rat ileum--a gnotobiotic group, a group with ileal self-filling blind loops, and a group with ileal Thiry-Vella loops. The results observed support the following conclusions. The volume percentage of the various components of the rat ileal wall of control animals was defined utilizing the micrometer component quantitator. Hypertrophy of the ileal muscularis externa within the ileal self-filling blind loops was observed, probably secondary to mechanical obstruction. Atrophy of the ileal epithelium within the gnotobiotic group and within the Thiry-Vella loops was observed, possibly secondary to an altered endogenous microbial flora. Recognition of quantitative variations among the histological components of the intestinal wall in association with physiological manipulations or pathologic states was (is) feasible by utilization of this component quantitative technique.

[Significance of deficient bacterial colonization in the pathogenesis of mucosal lesions in experimental blind loop syndrome]

A complete evaluation of the bacterial flora in jejunal self-filling blind loops was performed. The results show a significant increase in bacteria of the genera E. coli, Streptococcus and Bacteroides. In further experiments, jejunal self-filling blind loops were created in germ-free animals. In spite of the germ-free state the mucosa displayed marked hyperplasia. The same was true when the blind loops had been contaminated with aerobic bacteria. These results demonstrate that other factors in addition to bacterial overgrowth contribute to the mucosal damage observed in self-filling blind loops.

[Structural and functional findings in experimental blind loop syndrome]

Proximal and distal the blindsack a villus and crypt prolongation connected with a decreasing absorption of octanoate could be pointed out. The structural changes are very likely a hyperplasia of the mucosa. Within the blindsack a hyperplasia in connection with an accelerated proliferation of cells and an almost three and a halffold enlargement of the surface of the villi could be found. Simultaneously, the mucosa was damaged. An artificial bile duct as well as a neomycin therapy caused a decrease of the structural and functional changes but did not prevent the mucosal hyperplasia. These results are explained with adaptive processes of the small intestinal mucosa in a sense of hyperregeneration alterations of sprue typus.

Adaptative response of alpha- and beta-glucosidase kinetics along the villi of rat self-filling jejunal blind loops

Four and 12 days after the construction of self-filling jejunal blind loops in the rat, the apparent Km- and Vmax-values of lactase/beta-glucosidase and neutral alpha-glucosidase were determined by in-situ quantitative enzyme histochemistry, and changes in the villus-crypt architecture of the mucosa were examined by microdissection. The results were compared with corresponding data from sham-operated controls. The kinetics data were obtained from the base and the transition zone between medium and apical villus third by the use of a microdensitometric technique. The apparent Vmax of lactase/beta-glucosidase is significantly smaller than in the control rats at both measuring sites of the villi and even decreases from day 4 to day 12. The apparent Vmax of neural alpha-glucosidase is not affected, and thus the same increase in enzyme activity along the villi as in the controls is observed. The apparent Km of this enzyme, however, is already significantly increased on day 4 at both villus positions in the blind loops. A pronounced increase in villus surface area is detected in the blind loops as a result of an increase in crypt cell proliferation. The results indicate that enzymatic adaptation in the self-filling blind loops of rat jejunum exhibits different patterns for brush border alpha- and beta-glucosidases and is at least in part accomplished independently of the pronounced mucosal transformation occurring in this experimental condition.

[II. Etiological classification of the small bowel diseases (author's transl)]

A new classification of the small bowel diseases is proposed according to - the physiopathology; - the anatomo-pathology; - the etiology. In this second part, the ethiological classification is developed. One may distinguish the post-surgical lesions, congenital defects, the side-effects of drugs and the vascular lesions. Allergy and infection are especially studied. The main problems which may be solved in a next future are: the mechanism of chronic infections, the biochemical pathology and especially the normal and pathological immunology.

Pathogenesis of mucosal injury in the blind loop syndrome. Brush border enzyme activity and glycoprotein degradation

The effect of intestinal bacterial over-growth on brush border hydrolases and brush border glycoproteins was studied in nonoperated control rats, control rats with surgically introduced jejunal self-emptying blind loops, and rats with surgically introduced jejunal self-filling blind loops. Data were analyzed from blind loop segments, segments above and below the blind loops, and three corresponding segments in the nonoperated controls. Rats with self-filling blind loops had significantly greater fat excretion than controls and exhibited significantly lower conjugated:free bile salt ratios in all three segments. Maltase, sucrase, and lactase activities were significantly reduced in homogenates and isolated brush borders from the self-filling blind loop, but alkaline phosphatase was not affected. The relative degradation rate of homogenate and brush border glycoproteins was assessed by a double-isotope technique involving the injection of d-[6-(3)H]glucosamine 3 h and d-[U-(14)C]glucosamine 19 h before sacrifice, and recorded as a (3)H:(14)C ratio. The relative degradation rate in both homogenate and brush border fractions was significantly greater in most segments from rats with self-filling blind loops. In the upper and blind loop segments from rats with self-filling blind loops, the (3)H:(14)C ratios were higher in the brush border membrane than in the corresponding homogenates, indicating that the increased rates of degradation primarily involve membrane glycoproteins. Incorporation of d-[6-(3)H]glucosamine by brush border glycoproteins was not reduced in rats with self-filling blind loops, suggesting that glycoprotein synthesis was not affected. Polyacrylamide gel electrophoresis of brush border glycoproteins from the contaminated segments indicated that the large molecular weight glycoproteins, which include many of the surface hydrolases, were degraded most rapidly. Brush border maltase, isolated by immunoprecipitation, had (3)H:(14)C ratios characteristic of the most rapidly degraded glycoproteins. The results indicate that bacteria enhance the destruction of intestinal surface glycoproteins including disaccharidases. Since alkaline phosphatase, a glycoprotein, is not affected, the destruction is selective and presumably involves only the most exposed membrane components.

[Adaptive changes in intestinal mucosa of the small intestine as a result of intraluminal stress]

Under physiological conditions, the intestinal mucosa is the site of a delicate balance between cell proliferation in the crypt region and cell desquamation at the villus tips. This balance can be deranged by a number of endogenous or exogenous factors, oneof which is the intraluminal contents. This review discusses the effects of different modifications of the luminal milieu on the structure and function of the mucosa. Following intestinal resection or loop transposition, the contents reaching the remnant or the transposed loop differ markedly from those with which they come into contact under normal conditions. Hyperplasia without zonal transformation then develops in the experimental loop. The villi do not become wider, and changes in the strucutre of the epithelium are not observed. There are conflicting resutls in the literature concerning the enzyme activities in the individual enterocytes resulting from this hyperplasia. However, the epithelium its functionally immature, since transport capacities measured in vitro are reduced. On the other hand, the hyperplasia of the mucosa is such that absorptive capacities in vivo, when expressed in terms of intestinal length, are larger than normal. When the intestine is subjected to prolonged infusion of lactic acid, the enterocytes are damaged and increased exfoliation results. A similar result is obtained in the blind-loop syndrome, where the accumulation of bile acids and bacteria provides the stress responsible for the destruction of the enterocytes, and in non-tropical spure, where the epithelium is attacked by noxious peptides in the diet. The first consequence of the accelerated desquamation is epithelial hyperplasia without zonal transformation, though the enterocytes are damaged - in contrast to those of the resected intestine - and apparently possess reduced enzyme activities. If the application of the stress is continued, a stage is reached in which the cell proliferation does not suffice to counteract the cell loss at the villus tips. Then a zonal transformation occurs whereby, despite the lengthened crypts, the villi become shorter and wider until, in extreme cases, the mucosa is completely devoid of villi. The transport capacity in vitro and in vivo - even when expressed in terms of unit-length is reduced, and good correlations exist between the reduction in function and the diminution in surface area of the intestine. In a self-emptying blind loop, the intestine is devoid of all contact with nutritional material. Under these circumstances, hypoplasia of the mucosa develops in which the enterocytes appear unchanged, though in extreme cases they may possess reduced enzyme levels, and the absorption capacity in vivo is consequently reduced.

Functional, biochemical and morphological alterations in the intestines of rats with an experimental blind-loop syndrome

In rat self-filling blind loops and in the contiguous regions of the intestinal tract, considerable functional impairment, accompanied by pronounced morphological transformations of the mucosa, has been observed. The histological alterations consist of mucosal hypertrophy and a reduction in the villus height: crypt length ratio, which is indicative of a hyper-regenerative change. Various enzyme activities of the epithelial cells are reduced and the absorption otinal juices is greatly altered in favour of the free acids. Two mec,anisms have 0een dicids, or meta0olites from bacterial degradation, on the absorptive epithelium; 2. Reduced cellular maturity in response to the effect of bile acids and/or bacteria on the lifespan of the cells.

Small intestinal mucosal injury in the experimental blind loop syndrome. Light- and electron-microscopic and histochemical studies

Microscopic (light and electron) and histochemical abnormalities have been demonstrated in the jejunum of rats with the blind loop syndrome. Three groups of animals were studied: normal control animals, and animals with either self-filling (SF) or self-emptying (SE) blind loops. Vitamin B12 malabsorption and bacterial overgrowth occurred only in those animals with SF blind loops. Three jejunal segments were studied: the blind loop segment and the jejunal segments proximal and distal to the blind loop. In the animals with the blind loop syndrome, those with SF blind loops, the most striking findings occurred in the blind loop itself, with similar but less marked changes in the jejunum distal but not proximal to the blind loop segment. Hypertrophy of both crypts and villi was evident with focal abnormalities of villus architecture. Approximately 10 to 20% of the columnar cells in the upper half of the villi were swollen and vesiculated. By electron microscopy microvilli demonstrated a variety of degeneration changes and the glycocalyx and terminal web were disrupted. Mitochondria and endoplasmic reticulum (ER), both smooth and rough, were swollen. Concentric whorls of parallel membranes and long, curvilinear rough ER were present in the cytoplasm. Histochemically, there was loss of enzymatic activity in the epithelial brush border, mitochondria and ER. Inasmuch as bacterial invasion of the jejunal mucosa was not seen, the etiology of these changes is not known but may involve bacterial "toxins" or products of bacterial metabolism. These morphological observations demonstrate that both brush border and intracellular injury occur in the jejunal epithelial cell of rats with the experimental blind loop syndrome.