A comparative study on the effects of different bile salts on mucosal ATPase and transport in the rat jejunum in vivo.

The effects of deoxycholate, taurocholate and cholate on transport and mucosal ATPase activity have been investigated in the rat jejunum in vivo using closed-loop and perfusion techniques. In the closed-loops, 5 mM deoxycholate selectively inactivated (Na+ + K+)-ATPase, and net secretion of Na+ induced by 2.5 mM deoxycholate was due to reduced lumen to plasma flux of the ion; deoxycholate (2.5 mM) produced marked inhibition of 3-0-methylglucose transport. Luminal disappearance rates of deoxycholate (60.5 plus or minus 2.9% per g wet st of gut) greatly exceeded those of taurocholate (4.3 plus or minus 1.0). In the perfusion studies 1 mM deoxycholate induced net secretion of water, Na+ and C1-, and inhibited active glucose transport; concomitantly "total" ATPase, (Na+ + K+)-ATPase, and Mg-2+-ATPase were inhibited. At higher concentrations (5 mM) deoxycholate stimulated Mg-2+-ATPase activity. Taurocholate and cholate at 1mM had no effect on transport of (Na+ + K+)-ATPase. Mucosal lactase, sucrase and maltase activities were not affected by 1 mM deoxycholate, taurocholate or cholate. These results suggest that deoxycholate inhibits sodium-coupled glucose transport by inhibition of (Na+ + K+)-ATPase at the lateral and basal membranes of the epithelial cell, rather than from an effect at the brush-border membrane level.

Immunological phenomena in the jejunum and serum after reintroduction of dietary gluten in children with treated coeliac disease.

Jejunal mucosal immunoglobulin-containing cells of all three major classes (IgA, IgM, IgG) were increased in coeliac children on gluten-containing diets but only IgM cell numbers were raised in those on gluten-free diets. Patients with subtotal villous atrophy had greater numbers of immunoglobulin-containing cells than patients with normal mucosa. In previously treated patients studied before and after three months on a gluten-containing diet ther was an increase in all three classes of cell, IgM containing cells showing the greatest proportional rise. Basement membrane staining with anti-IgA serum occurred in coeliacs and was most intense in untreated patients. Apart from one patient with very low levels of serum IgA, serum immunoglobulins did not differ from normal. However, after reintroduction of gluten to the diet a significant fall in serum IgM concentrations occurred compared with levels in the same patients while on gluten-free diets. It seems probable that both IgA and IgM systems are important in the immunopathogenesis of the small intestinal lesion of childhood coeliac disease.

Cellular infiltrate of the jejunum after re-introduction of dietary gluten in children with treated coeliac disease.

Jejunal lamina propria plasma cells and eosinophils and intraepithelial lymphocytes were raised in coeliac children on gluten-containing diets, but only intraepithelial lymphocytes were increased in patients on gluten-free diets. In contrast, lamina propria lymphocytes were reduced in children with coeliad disease on gluten-containing diets but were normal in paitents on gluten-free diets. In children with coeliac disease who were studied serially, lamina propria plasma cells and eosinophils and intraepithelial lymphocytes increased, and lamina propria lymphocytes decreased, within three months of the reintroduction of gluten to the diet. These observations are essentially similar to those made in the adult form of the disease and suggest that more than one type of immunological reaction is involved in the pathogenesis of the jejunal lesion.

[Inflammatory bowel disease in childhood]. / Malattia infiammatoria dell'intestino in età pediatrica.

Inflammatory bowel disease in childhood is becoming increasingly important as a result of a marked increase in incidence occurring over the past 20 years. In Crohn's disease the onset is commonly insidious, with symptoms such as growth failure, which do not immediately suggest intestinal disease. This may result in a correct diagnosis being delayed for several years. The role of paediatric colonoscopy is discussed, together with the macroscopic and microscopic appearances of the lesions. The indications and efficacy of drug therapy in Crohn's disease and ulcerative colitis are outlined and the importance of nutritional support, particularly in children with growth failure, is discussed. The indications for surgery are summarised and the need for a multidisciplinary approach, particularly in cases of fulminating colitis where early surgery is indicated, is emphasised. Most children with inflammatory bowel disease do reasonably well and even those children undergoing proctocolectomy adapt to a stoma provided they receive optimal psycho-social preparation and support.

Mechanisms of action of loperamide.

The beneficial effect of loperamide in some children with severe protracted diarrhoea which persisted when nil by mouth, made us suspect that loperamide may have an antisecretory action. Using a steady-state perfusion technique in rat jejunum we showed that loperamide inhibits cholera toxin induced secretion of water, sodium and chloride (p less than 0.001). This antisecretory action was blocked by naloxone and not mediated via an effect on tissue cyclic AMP level or adenylate cyclase activity. More recently we have studied the effect of loperamide on secretion of water in the rat jejunum induced by other agents with differing mechanisms of action. The first set of observations suggest that loperamide's antisecretory effect is mediated via opiate receptors either distal to, or separate from the adenylate cyclase/cyclic AMP pathway. Our more recent studies support the notion that loperamide has an effect on specific transport systems rather than non-specific passive diffusional processes.

Fat absorption in the newborn.

Dietary fat is an important source of energy to the newborn. Pancreatic lipase and esterase activity are both low in newborns, particularly in premature ones; similarly, bile salt metabolism is markedly compromised. This could result in grossly defective intraluminal lipolysis and micellar solubilisation, leading to appreciable steatorrhea and energy loss. Lingual lipase and bile salt-stimulated lipase (BS-SL), however, play an important compensatory role. Lingual lipase is secreted from branching serous glands (von Ebner's glands) located on the dorsal aspect of the posterior region of the tongue, and its physicochemical properties are highly suited to passage through the stomach into the small intestine; a high fat diet and the act of suckling stimulates this enzyme's activity, and it may act in a synergistic fashion with pancreatic lipase. BS-SL (i.e. milk lipase) also has properties which are well designed for promoting fat absorption in the newborn. For example, it has no positional specificity for the ester bonds of the triglyceride molecule, and the optimal concentration of bile salts required for activation are low.

The problem of bacterial diarrhoea.

The reported incidence of "pathogenic" bacteria, as judged by serotype, in the stools of children with acute diarrhoea has varied from 4 to 33% over the last twenty years. Techniques such as tissue culture provide a means for detecting enterotoxin-producing strains of bacteria, strains which often do not possess "pathogenic" serotypes. "Pathogenicity" requires redefinition, and the aetiological importance of bacteria in diarrhoea is probably considerably greater than previous reports have indicated. Colonization of the bowel by a pathogen will result in structural and/or mucosal abnormalities, and will depend on a series of complex interactions between the external environment, the pathogen, and the host and its resident bacterial flora. Enteropathogenic bacteria may be broadly classified as (i) invasive (e.g. Shigella, Salmonella and some Escherichia coli) which predominantly affect the distal bowel, or (ii) non-invasive (e.g. Vibrio cholerae and E. coli) which affect the proximal bowel. V. cholerae and E. coli elaborate heat-labile enterotoxins which activate adenylate cyclase and induce small intestinal secretion; the secretory effects of heat-stable E. coli and heat-labile Shigella dysenteriae enterotoxins are not accompanied by cyclase activation. The two major complications of acute diarrhoea are (i) hypernatraemic dehydration with its attendant neurological, renal and vascular lesions, and (ii) protracted diarrhoea which may lead to severe malnutrition. Deconjugation of bile salts and colonization of the small bowel with toxigenic strains of E. coli may be important in the pathophysiology of the protracted diarrhoea syndrome. The control of bacterial diarrhoea requires a corrdinated political, educational, social, public health and scientific attack. Bacterial diarrhoea is a major health problem throughout the world, and carries an appreciable morbidity and mortality. This is particularly the case during infancy, and in those developing parts of the world where malnutrition is common. This paper is concerned mainly with acute bacterial diarrhoea, and reviews the problem as a whole.

UNICEF/W.H.O. glucose electrolyte solution not always appropriate.

PIP: The authors defended Dr. Kahn's and Dr. Blum's suggestion, reported in the May 17, 1980 issue of Lancet, that the formula for making GES (glucose electrolyte solution), used for the management of gastroenteritis, should be determined by the age and condition of the patients in each locality. They disagreed with the proposal of Dr. Clements, reported in the July 5, 1980 issue of Lancet, that all patients could be treated with a single solution, the UNICEF/WHO CES, or with a dilution of this single solution. Recent studies confirmed that there was considerable epidemiological variation in the type and degree of electrolyte disturbances among infants with gastroenteritis. Factors such as age, nutritional status, climate, and the type of pathagens were linked to different type of electrolyte disturbances. These differences should be taken into account in formulating the appropriate GES.^ieng

The effects of different bile salts on the absorption of fluid, electrolytes, and monosaccharides in the small intestine of the rat in vivo.

The effects of different bile salts on the absorption of fluid, electrolytes, and monosaccharides have been investigated in the rat small intestine in vivo. In the jejunum, deoxycholate (1 mM) impaired absorption of water and potassium, but not of sodium or glucose; at higher concentrations (2.5 and 5 mM) secretion of fluid and electrolytes occurred, and glucose and fructose absorption was impaired. By contrast, in the ileum, 1 mM deoxycholate failed to inhibit fluid and electrolyte absorption, and a concentration of 10 mM was required completely to inhibit absorption; secretion was not observed in the ileum. Chenodeoxycholate (5 mM) produced a similar effect to deoxycholate on fluid and electrolyte absorption in both jejunum and ileum, but taurocholate (5 mM) and taurodeoxycholate (5 mM) were ineffective.In jejunum, cholate, taurocholate, and taurodeoxycholate, each at a concentration of 5 mM, were less effective inhibitors of glucose transport than deoxycholate; chenodeoxycholate failed to inhibit glucose absorption. Deoxycholate produced histological damage at 5 mM, but not at lower concentrations. The functional and structural abnormalities were shown to be reversible phenomena. These findings may be relevant to the pathogenesis of diarrhoea in patients with bacterial overgrowth in the small intestine.

Absorption of vitamin E in children with biliary obstruction.

Serum vitamin E levels and red cell haemolysis were measured in 17 children with biliary obstruction after oral and intramuscular loading tests, and during long-term oral administration of differing doses of a fat-soluble and water-miscible preparation of alpha-tocopheryl acetate. The results suggested a severe defect in the intestinal absorption of both preparations. In three of the children who were studied during periods of improving biliary obstruction, absorption was shown to have improved. Bile plays a major role in the absorption of vitamin E from the intestinal tract and the exact mechanism of its action requires further elucidation.

Mucosal (Na+-K+)-ATPase and adenylate cyclase activities in children with toddler diarrhea and the postenteritis syndrome.

Assays for (Na+-K+)-ATPase and basal, fluoride stimulated and percentage of activation of adenylate cyclase have been established for small portions of human jejunal biopsies. Control means and ranges have been established for each activity in a group of children with failure to thrive but no gastrointestinal disease. Activities of (Na+-K+)-ATPase and percentage of activation and basal activity of adenylate cyclase are increased in children with toddler diarrhea. (Na+-K+)-ATPase activity is reduced in children with active postenteritis syndrome, and recovery from this syndrome is associated with an increase in this activity and of percentage of activation and basal activity of adenylate cyclase.

The relative importance of the factors involved in the absorption of vitamin E in children.

The vitamin E status and ease of repletion in groups of children with coeliac disease, intestinal lymphangiectasia, and abetalipoproteinaemia was studied and compared with earlier studies in cystic fibrosis and obstructive jaundice. Each group represents an experimental model in which one of the transport steps involved in the absorption of vitamin E is defective or absent and thus the relative importance of these factors could be determined. Chylomicron formation and an adequate intraluminal concentration of bile salts were found to be the most important factors for the efficient absorption of the vitamin. The results in the five groups of patients have therapeutic implications if it is considered desirable to correct vitamin E deficiency states.

Influence of mixtures of taurocholate, fatty acids, and monolein on the toxic effects of deoxycholate in rat jejunum in vivo.

The influence of mixtures of taurocholate (TC), oleic acid (OA), caprylic acid (CA), and monolein (MO) on the toxic effects of deoxycholate (DC) in rat jejunum have been investigated using both a closed loop and perfusion technique. DC induced net secretion of water and electrolytes, inhibited glucose transport and transmural potential difference (PD), and inactivated mucosal "total" and (Na+ -K+)-adenosine triphosphatase. Secretion was reversed to absorption when the instilled or perfused solutions were composed of mixtures of DC, TC and OA; substitution of MO or CA for OA produced a similar effect. DC-induced inhibition of PD, glucose absorption, and mucosal adenosine triphosphatase activity was abolished when DC was mixed with TC and OA. Oleic acid emulsions had no effect on secretion induced by DC. Absorption of DC was inhibited from mixed micellar solutions (TC, OA, DC) but not from pure micellar solutions (TC, DC). These results indicate that the presence of taurocholate and fatty acids or monolein within the intestinal lumen markedly modify a number of the toxic effects of DC on jejunal function. The clinical effects of DC on intestinal function in man may therefore depend on the relative concentrations of other bile salts and lipids within the intestinal lumen.

Limitations of xylose tolerance test as a screening procedure in childhood coeliac disease.

The usefulness of the xylose tolerance test as a screening procedure for coeliac disease has been reassessed in 54 children with suspected coeliac disease. 5- and 24-hour urinary excretion rates of xylose were of no value in discriminating between patients with and without coeliac disease; similarly, the 3-hour blood xylose concentration was nondiscriminatory. Three (15-8%) patients with subtotal villous atrophy and 8 (61-5%) with partial villous atrophy due to coeliac disease had one-hour blood xylose values which fell within the normal range. The effect of withdrawal or reintroduction of dietary gluten on sequential one-hour blood xylose levels was variable and generally unhelpful in predicting those patients who developed gluten-induced mucosal changes. The results of the present study emphasize the serious limitations of the xylose tolerance test as a screening procedure in childhood coeliac disease. It is recommended that the use of the urinary xylose test should be abandoned in the paediatric population. A normal one-hour blood xylose value does not exclude a diagnosis of coeliac disease even in young children who have never received a gluten-free diet. A clinical suspicion of coeliac disease remains the most important single factor in deciding whether to preform a jejunal biopsy.

Obstructive jaundice secondary to chronic midgut volvulus.

A case of progressive extrahepatic biliary obstruction due to chronic midgut volvulus secondary to malrotation in a 5-month-old girl is presented. The obstruction to the bile duct was relieved after correction of the malrotation and division of the obstructing bands.

Test meal for assessing intraluminal phase of absorption in childhood.

A test meal for assessing the intraluminal phase of absorption in childhood has been validated. 132 test meals were administered to 110 patients aged 2 weeks to 18 years (mean age 4.3 years). 10 children with suspected malabsorption, who were proven to be normal after extensive investigation, constituted the control group. The activities of pancreatic enzymes, and the total and individual bile salt concentrations are presented for the control subjects, and pancreatic enzyme levels in this group are compared with those seen in children with pancreatic insufficiency (cystic fibrosis). The test meal has been designed so that it can be administered to children with suspected gluten, cows' milk, or disaccharide intolerance. The control data provided a basis for the interpretation of information obtained from the application of such a test meal to the clinical investigation of children with suspected malabsorption.

Optimization and validation of assays to estimate pancreatic esterase activity using well-characterized micellar solutions of cholesteryl oleate and tocopheryl acetate.

Studies have been carried out to determine the maximal solubilization of cholesteryl oleate and tocopheryl acetate within mixed bile salt-fatty acid micelles and to establish reproducible assays for pancreatic esterase activity using these micellar substrates. At pH 8.5, using 30 mM sodium taurocholate and 10 mM oleic acid, reproducible micellar solutions of the esters could be prepared giving micellar concentrations of 0.4 mM and 0.1 mM for tocopheryl acetate and cholesteryl oleate, respectively. Conditions were then optimized to estimate pancreatic esterase activity using these micellar-solubilized substrates. Maximal activity was obtained at pH 8.5 with 2-4 mM oleic acid and 15-30 mM sodium taurocholate, and gave coefficients of variation for the assays of 7.4% and 20.2% using tocopheryl acetate and cholesteryl oleate, respectively, as substrates. Micellar-solubilized cholesteryl oleate and tocopheryl acetate, together with a non-micellar system using p-nitrophenyl acetate, were used to estimate esterase activity in human duodenal aspirates and rat pancreatic homogenates. Esterase activity in children with cystic fibrosis was greatly reduced and paralleled tryptic and pancreatic lipase activity, which suggested that the esterase activity was pancreatic in origin. The results of this study, therefore, provide a basis for future investigations concerned with the hydrolysis and absorption of dietary esters.