Distribution and Neurochemistry of the Porcine Ileocaecal Valve Projecting Sensory Neurons in the Dorsal Root Ganglia and the Influence of Lipopolysaccharide from Different Serotypes of Salmonella spp. on the Chemical Coding of DRG Neurons in the Cell Cultures

The ileocecal valve (ICV)—a sphincter muscle between small and large intestine—plays important roles in the physiology of the gastrointestinal (GI) tract, but many aspects connected with the innervation of the ICV remain unknown. Thus, the aim of this study was to investigate the localization and neurochemical characterization of neurons located in the dorsal root ganglia and supplying the ICV of the domestic pig. The results have shown that such neurons mainly located in the dorsal root ganglia (DRG) of thoracic and lumbar neuromers show the presence of substance P (SP), calcitonin gene-related peptide (CGRP), and galanin (GAL). The second part of the experiment consisted of a study on the influence of a low dose of lipopolysaccharide (LPS) from Salmonella serotypes Enteritidis Minnesota and Typhimurium on DRG neurons. It has been shown that the LPS of these serotypes in studied doses does not change the number of DRG neurons in the cell cultures, but influences the immunoreactivity to SP and GAL. The observed changes in neurochemical characterization depend on the bacterial serotype. The results show that DRG neurons take part in the innervation of the ICV and may change their neurochemical characterization under the impact of LPS, which is probably connected with direct actions of this substance on the nervous tissue and/or its pro-inflammatory activity.

Mucin histochemical analysis of the ileocaecal valve and lymphoid tissues of the terminal ileum: role against tumour invasion

OBJECTIVES

We previously reported clinicopathological data on 78 patients who underwent a right hemicolectomy from 1990 to 1997. Our results indicated that the ileocaecal valve [ICV] and lymphoid tissue of the terminal ileum might, together, play a protective and local immune role against carcinoma invasion. Furthermore, we previously reported that mucin histochemical features of the transitional zone [TZ] might also play a role in predicting metastasis and, thus, prognosis. The aim of this study was to examine the clinicopathological correlation between lymphoid infiltration and mucin secretion in the terminal ileum with carcinoma of the right colon.

METHODS

According to the proximity of the tumour to the ICV, a total of 16 specimens with lymphoid infiltration to and around [< 1 cm] the ICV were studied in order to identify the mucin expression and histochemical features of the TZ as a prognostic indicator.

RESULTS

Patients with sulphomucin-staining tumours in the terminal ileum and ICV had a relatively favourable course. Even when the clinical staging was the same for different tumours, greater lymphoid infiltration in the ICV, greater staining for sulphomucin in the ICV and a relatively favourable course were observed in nine patients. The sulphomucin-type TZ showed a favourable course as well. On the other hand, patients with sialomucin staining of the ICV and the TZ tended to have low-grade lymphoid infiltration and a very poor course, although two patients with moderately high-grade lymphoid infiltration had a favourable course. Overall survival was significantly associated with the mucin type of the ICV [p < 0.01].

CONCLUSIONS

Our results indicated that lymphoid infiltration of the terminal ileum may lead to an alteration in mucin secretion and, thus, play a protective role in the invasive and metastatic process of advanced right colon carcinoma.

From brain to bile. Evidence that conjugation and omega-hydroxylation are important for elimination of 24S-hydroxycholesterol (cerebrosterol) in humans

The brain is the almost exclusive site of formation of 24S-hydroxycholesterol in man, and there is a continuous flux of this oxysterol across the blood-brain barrier into the circulation. The hepatic metabolism of 24S-hydroxycholesterol was studied here by three different approaches: incubation of tritium-labeled 24S-hydroxycholesterol with human primary hepatocytes, administration of tritium-labeled 24S-hydroxycholesterol to a human volunteer, and quantitation of free and conjugated 24S-hydroxycholesterol and its neutral metabolites in ileocecal fluid from patients with ileal fistulae. 24S-Hydroxycholesterol as well as 24R-hydroxycholesterol were converted into bile acids by human hepatocytes at a rate of about 40% of that of the normal intermediate in bile acid synthesis, 7 alpha-hydroxycholesterol. There was also a conversion of 24S-hydroxycholesterol into conjugate(s) of 5-cholestene-3 beta,24S,27-triol at a rate similar to the that of conversion into bile acids. When administered to a human volunteer, labeled 24S-hydroxycholesterol was converted into bile acids at about half the rate of simultaneously administered labeled 7 alpha-hydroxycholesterol. Free, sulfated, and glucuronidated 24S-hydroxycholesterol and 5-cholestene-3 beta,24,27-triol were identified in ileocecal fluid. The excretion of these steroids was about 3.5 mg/24 h, amounting to more than 50% of the total estimated flux of 24S-hydroxycholesterol from the brain. It is concluded that 24S-hydroxycholesterol is a less efficient precursor to bile acids and that about half of it is conjugated and eliminated in bile as such or as a conjugate of a 27-hydroxylated metabolite. The less efficient metabolism of 24S-hydroxycholesterol may explain the surprisingly high levels of this oxysterol in the circulation and is of interest in relation to the suggested role of 24S-hydroxycholesterol as a regulator of cholesterol homeostasis.

Nutritional implications of significant small bowel resection

Nutrition support of the patient with short bowel syndrome is determined by the extent and location of bowel resection, the functional status of residual bowel, and presence or absence of the ileocecal valve. The authors discuss the consequences and treatments for bowel resection.

Distribution of mast cells in human ileocecal region

The number and histochemistry of mast cells were analyzed in surgical specimens of the ileocecal junction and neighboring intestinal segments. All the basophilic cells contained tryptase and some were immunoreactive for chymase, vasoactive intestinal polypeptide, or nitric oxide synthase. The medium density of mast cells per square millimeter was 31.90, 110.38, 72.83, 29.80, and 32.70, in the mucosa, submucosa, inner circular, outer circular, and longitudinal muscle layers, respectively. Mast cell density was higher at the ileocecal junction (for all layers together, 79.29 mast cells/mm2) than elsewhere (mast cells/mm2: ileum, 52.29; cecum, 59.22; cecocolonic junction, 54.65; ascending colon, 48.63). The differences among layers and among segments were significant and might be due to layer- and region-specific mast cell roles. Mast cell richness in the muscle coat, especially in the inner circular muscle layer, might be important in regulating its motility.

Role of nitric oxide in mediating non-adrenergic non-cholinergic relaxation of the cat ileocecal sphincter

The participation of nitric oxide (NO) in field stimulation- or nicotine-evoked non-adrenergic non-cholinergic (NANC) relaxation of cat ileocecal sphincter was studied in vitro. During a 30 microM noradrenaline-induced contraction, both the application of electrical field stimulation (2-20 Hz, 0.2 ms, supramaximal current intensity, 10 s duration) and (-)-nicotine (10-500 microM) produced a tetrodotoxin-sensitive relaxation. The maximal relaxation was observed at 10 Hz or 100 microM (-)-nicotine. In 12 out of 19 strips the pretreatment with N omega-nitro-L-arginine (100 microM) decreased the amplitude of the field stimulation-evoked relaxation, while in the remaining strips the relaxation was transformed into a contraction. By increasing the concentration of N omega-nitro-L-arginine up to 1 mM all strips responded to field stimulation with a frequency-dependent tetrodotoxin-resistant contraction. N omega-Nitro-L-arginine (100 microM) completely inhibited the nicotine-induced relaxation. L-Arginine (1 mM) restored the amplitude of both field stimulation- and nicotine-evoked relaxations. These data indicate that NO appears to be involved in both field stimulation- and nicotine-evoked NANC relaxations. Evidence has been obtained for the existence of tetrodotoxin-resistant NANC contraction in cat ileocecal sphincter.

[The differentiation of tumor cells of the human large intestine during the acquisition of multiple drug resistance]

By selection in the medium containing increasing actinomycin D concentrations two sublines with acquired multidrug resistance (MDR) caused by P-glycoprotein (P170) overproduction were isolated. The obtained cell lines as well as parent cells grow in vitro as morphologically organized aggregates, so-called organoids. Comparative electron microscopic study of sensitive and drug resistant organoids has shown that the development of MDR was accompanied by the enhancement of the tumour cell differentiation: the percentage of differentiated cells, the extent of their maturity, and the quantity of lumens were higher in MDR organoids than in parent cell line. The size of glandular structures in resistant organoids was also enlarged. Possible mechanisms of observed phenomenon are discussed.

Absence of secretory component expression by epithelial cells overlying rabbit gut-associated lymphoid tissue

The expression of secretory component by epithelial cells overlying intestinal lymphoid aggregates was examined immunocytochemically in rabbits. Intensely labeled epithelial cells were distributed along surfaces of villi surrounding follicles in jejunal and ileal Peyer's patches and along interdomal epithelium in sacculus rotundus and appendix. Secretory component labeling extended from within crypts and appendiceal crevices to the tips of villi and interdomal regions. In contrast, no immunologically detectable secretory component sites were observed in follicle-associated epithelial cells. In crypts and crevices supplying follicles, epithelial cells facing the lamina propria of villi and interdomal epithelium expressed secretory component, but cells flanking the follicle domes lacked secretory component immunostaining, with a clear demarcation between positive and negative zones at the base of the stem cell regions. These findings demonstrate a unique difference in the expression of the receptor for immunoglobulin A antibody between follicle-associated and non-follicle-associated epithelium.

Colonic dysfunction during cholera infection

To study the function of the colon in cholera, 12 patients with acute cholera diarrhea were subjected to measurements of ileocecal flow rates, fecal flow rates, and ionic compositions of stool and ileocecal fluid. Subtraction of fecal flow rates from ileocecal flow rates was taken as a measure of net fluid absorption by the colon. Additionally, these patients underwent colonoscopic perfusion of the colon that measured net colonic absorption rates of water and ions. The mean ileocecal flow rate was 7.9 ml/min compared with a mean fecal flow rate of 7.6 ml/min, indicating a small mean net fluid absorption by the colon of +0.30 ml/min. By colonoscopic perfusion, 6 patients showed net colonic absorption of water and 6 patients net secretion of water with a slight mean net fluid secretion of -0.03 ml/min. The handling of ions by the colon showed mean net absorption of sodium (100 mu Eq/min) and chloride (127 mu Eq/min), and net secretions of potassium (-42 mu Eq/min) and bicarbonate (-112 mu Eq/min). During convalescence, 5 patients who were studied again all showed net colonic absorption of water, and the handling of potassium changed significantly from net secretion in acute disease to net absorption (p less than 0.05). These results showed that the colon contributes to the clinical expression of cholera by failing to absorb water normally, and by secreting potassium at high rates.

[Resection of the valvula bauhini and its effect on the metabolism. An experimental study in animals (author's transl)]

In animal experiments (20 mongrel dogs) malabsorption was induced by resection of 100 cm ileum. Subsequently the influence of the ileocoecal valve (Valvula Bauhini) in absorption was studied. In one group of animals intestinal continuity was reestablished by ileoileostomy, in a second by ileocolostomy. The results of the absorption studies were compared with a healthy control group. After ileoileostomy animals do not lose weight, serum cholesterol and protein remain normal. Oral tolerance tests with Triolein-iodine-131 and Cyanocobalamine show results identical with those of the control group. After ileocolostomy all these parameters are lowered--partially to a pathological level. It is concluded that in all operations in the area of the terminal ileum and colon the Valvula Bauhini should be retained if possible.