Selective sparing of goblet cells and paneth cells in the intestine of methotrexate-treated rats

Proliferation, differentiation, and cell death were studied in small intestinal and colonic epithelia of rats after treatment with methotrexate. Days 1-2 after treatment were characterized by decreased proliferation, increased apoptosis, and decreased numbers and depths of small intestinal crypts in a proximal-to-distal decreasing gradient along the small intestine. The remaining crypt epithelium appeared flattened, except for Paneth cells, in which lysozyme protein and mRNA expression was increased. Regeneration through increased proliferation during days 3-4 coincided with villus atrophy, showing decreased numbers of villus enterocytes and decreased expression of the enterocyte-specific genes sucrase-isomaltase and carbamoyl phosphate synthase I. Remarkably, goblet cells were spared at villus tips and remained functional, displaying Muc2 and trefoil factor 3 expression. On days 8-10, all parameters had returned to normal in the whole small intestine. No methotrexate-induced changes were seen in epithelial morphology, proliferation, apoptosis, Muc2, and TFF3 immunostaining in the colon. The observed small intestinal sparing of Paneth cells and goblet cells following exposure to methotrexate is likely to contribute to epithelial defense during increased vulnerability of the intestinal epithelium.

Megarectum in constipation

BACKGROUND

Faecal impaction is frequently observed in children with chronic constipation. The term megarectum is often used to describe this finding.

AIM

To evaluate rectal functioning and rectal measures in constipated children with a filled rectum, in order to define the terms faecal impaction, enlarged rectum, and megarectum.

METHODS

All children underwent radiological investigation, colonic transit time study, anorectal manometry, and rectal volume and rectal wall compliance measurements. Patients with faecal impaction were compared with controls, who had an empty rectum on digital rectal examination.

RESULTS

A total of 31 patients and six controls were included in the study. The mean duration of complaints was 4.2 years and all had faecal incontinence. The colonic transit times in the patients showed a distinct delay in the rectosigmoid segment. Anorectal manometry was not significantly different between patients and controls. The rectal width in patients was 0.68 and in controls 0.52 with an upper limit of 0.61. The pressure-volume curve in patients showed significant less relaxation at a distension of 50 ml. The slope of the curve (corresponding with rectal wall compliance) was comparable for patients and controls.

CONCLUSIONS

We suggest that faecal impaction is a filled rectum found on digital rectal examination; an enlarged rectum is defined by a rectopelvic ratio greater than 0.61; and megarectum is defined in those with significant abnormalities found with anorectal manometry, pressure-volume curves, or rectal compliance investigation. A diminished relaxation of the rectum on rectal distension could be the first sign of megarectum in children with chronic constipation.

[Percutaneous endoscopic gastrostomy in children with psychomotor retardation; less complaints and not as stressful]

OBJECTIVE

To evaluate the effects of percutaneous endoscopic gastrostomy (PEG) in children with psychomotor retardation.

DESIGN

Prospective.

METHOD

Data on symptoms, pros and cons and complications were collected by means of questionnaires from the parents of children with psychomotor retardation and severe nutritional problems in whom a PEG tube had been introduced between August 1995 and March 1998 in the department of Children's Gastroenterology and Nutrition of the Emma Children's Hospital/Academic Medical Centre in Amsterdam, the Netherlands, comparing the situations before the introduction and 6 and 18 months afterward.

RESULTS

The patient group consisted of 17 boys and 23 girls with a mean age of 6 years and 3 months (range 8 months-10 years and 1 month). The frequency of vomiting and of airway infections decreased and the general nutritional condition improved. Restlessness and pain occurred less often in over half the children. The disadvantages most often reported were the logistics concerning the feeding (n = 11) and the reduced contact with the child (n = 10). Thirteen children displayed mild side effects such as skin irritation and proud flesh. Technical problems consisted of leakage (n = 11) and obstruction of the tube (n = 2). In one child, introduction of the tube was followed by a major complication.

CONCLUSION

The PEG tube in this patient group reduced the frequency of complaints about nutrition and constituted a patient-friendly alternative to the nasal tube.

Stress stimulates transepithelial macromolecular uptake in rat jejunum

Evidence suggests that stress may be a contributing factor in intestinal inflammatory disease; however, the involved mechanisms have not been elucidated. We previously reported that acute stress alters epithelial physiology of rat intestine. In this study, we documented stress-induced macromolecular transport across intestinal epithelium. After exposure of Wistar-Kyoto rats to acute restraint stress, transport of a model protein, horseradish peroxidase (HRP), was assessed in isolated segments of jejunum. The flux of intact HRP was significantly enhanced across intestine from stressed rats compared with controls. Electron microscopy revealed HRP-containing endosomes within enterocytes, goblet cells, and Paneth cells of stressed rats. The number and area of HRP endosomes within enterocytes were found to be significantly increased by stress. HRP was also visualized in paracellular spaces between adjacent epithelial cells only in intestine from stressed rats. Atropine treatment of rats prevented the stress-induced abnormalities of protein transport. Our results suggest that stress, via a mechanism that involves release of acetylcholine, causes epithelial dysfunction that includes enhanced uptake of macromolecular protein antigens. We speculate that immune reactions to such foreign proteins may initiate or exacerbate inflammation.

Regulation of lactase and sucrase-isomaltase gene expression in the duodenum during childhood

BACKGROUND

In children, lactase and sucrase-isomaltase are essential intestinal glycohydrolases, and insufficiency of either enzyme causes diarrhea and malnutrition. Little is known about the regulation of lactase and sucrase-isomaltase expression in the duodenum during childhood. In this study, the mechanisms of regulation of duodenal expression of both enzymes were examined in a study population with ages ranging from 1 to 18 years.

METHODS

Duodenal biopsy specimens from 60 white children were used to analyze tissue morphology and to quantify lactase and sucrase-isomaltase mRNA and protein.

RESULTS

Among healthy subjects, high interindividual variability was noted in both mRNA and protein levels for lactase and sucrase-isomaltase. Lactase mRNA level per subject did not correlate with sucrase-isomaltase mRNA level and thus appeared independent. Both lactase and sucrase-isomaltase protein levels correlated significantly with their respective mRNA levels. For each enzyme, a significant inverse correlation was observed between the degree of villus atrophy and mRNA levels. Aging from 1 to 18 years did not result in significant changes in mRNA or protein levels of either enzyme. Immunostaining patterns within the duodenal epithelium for lactase differed from sucrase-isomaltase in adjacent sections, illustrating independent regulation at the cellular level.

CONCLUSIONS

In the duodenum of white children, lactase and sucrase-isomaltase seem primarily regulated at the transcriptional level. The expression of each enzyme in the intestinal epithelium is regulated by an independent mechanism. Lactase and sucrase-isomaltase exhibit stable mRNA and protein levels in healthy children as they grow to adulthood. Mucosal damage affected levels of both enzymes negatively.

Pediatric duodenal biopsies: mucosal morphology and glycohydrolase expression do not change along the duodenum

BACKGROUND

Duodenal mucosal biopsies are routinely taken for diagnosis in children with complaints of the upper gastrointestinal tract. Surprisingly, little is known about the usefulness of proximal duodenal versus distal duodenal biopsies for routine diagnostic purposes. This study evaluated the comparability of proximal and distal duodenal biopsies with respect to mucosal morphology as well as glycohydrolase expression as an indicator of intestinal epithelial function.

METHODS

Specimens obtained in duodenal endoscopic biopsies from 64 children, ranging in age from 3 months to 18 years with normal or affected mucosa, were studied. Biopsies were performed in anatomically defined regions in the bulbus duodeni (the very proximal part of the duodenum) and distally of the papilla of Vater (distal of the pancreatic duct). Biopsy specimens were paraformaldehyde-fixed for histologic examination and immunohistochemical evaluation or were homogenized to isolate RNA. Crypt/villus morphology was assessed as is routinely determined by pathologists. In addition, several aspects of lactase and sucrase-isomaltase expression as paradigms of intestinal brush border enzymes were assessed: localization at the cellular level, semiquantitative immunohistochemistry, and quantitative measurement of the messenger RNA levels of the respective brush border glycohydrolases.

RESULTS

As anticipated, there was a wide interpatient variation in mucosal morphology and expression of lactase and sucrase-isomaltase. Nonetheless, the consistent finding was that in each patient, measurements of morphology and lactase and sucrase-isomaltase gene expression were very similar between samples obtained in the proximal and distal biopsies.

CONCLUSIONS

Biopsies performed in either location in the duodenum are equally suitable for diagnostic workup of patients suspected of mucosal abnormalities affecting morphology or small intestinal brush border glycohydrolase activities.

Intestinal carbamoyl phosphate synthase I in human and rat. Expression during development shows species differences and mosaic expression in duodenum of both species

The clinical importance of carbamoyl phosphate synthase I (CPSI) relates to its capacity to metabolize ammonia, because CPSI deficiencies cause lethal serum ammonia levels. Although some metabolic parameters concerning liver and intestinal CPSI have been reported, the extent to which enterocytes contribute to ammonia conversion remains unclear without a detailed description of its developmental and spatial expression patterns. Therefore, we determined the patterns of enterocytic CPSI mRNA and protein expression in human and rat intestine during embryonic and postnatal development, using in situ hybridization and immunohistochemistry. CPSI protein appeared during human embryogenesis in liver at 31-35 e. d. (embryonic days) before intestine (59 e.d.), whereas in rat CPSI detection in intestine (at 16 e.d.) preceded liver (20 e.d.). During all stages of development there was a good correlation between the expression of CPSI protein and mRNA in the intestinal epithelium. Strikingly, duodenal enterocytes in both species exhibited mosaic CPSI protein expression despite uniform CPSI mRNA expression in the epithelium and the presence of functional mitochondria in all epithelial cells. Unlike rat, CPSI in human embryos was expressed in liver before intestine. Although CPSI was primarily regulated at the transcriptional level, CPSI protein appeared mosaic in the duodenum of both species, possibly due to post-transcriptional regulation.

Treatment of defaecation problems in children: the role of education, demystification and toilet training

To evaluate the effect of education in children with chronic defaecation problems, a prospective 6-week intervention study was designed. A total of 54 children (5-14 years) underwent an education programme, with demystification of symptoms and advice about diet and toilet training. The present treatment was continued. After 6 weeks, children with persistent problems received biofeedback training with a follow up of 1 year. The intervention programme was successful in 8 children (15%). Biofeedback training was successful in 49% of the remaining group after 1 year.

CONCLUSION

A total of 15% of the children with chronic defaecation problems seen at a referral centre could surprisingly be helped by a simple education programme with, demystification and toilet training. Further studies evaluating treatment in children with defaecation problems should account for the primary effect of these measures.

Rapid transepithelial antigen transport in rat jejunum: impact of sensitization and the hypersensitivity reaction

BACKGROUND & AIMS

Intestine from sensitized rats develops a rapid secretory response to luminal antigen challenge that depends on activation of subepithelial mast cells. The aim of this study was to determine the timing and route of the transepithelial protein antigen transport.

METHODS

Rats were sensitized to horseradish peroxidase (HRP). After 10-14 days, jejunal segments were resected, mounted in Ussing chambers, and challenged with HRP on the luminal side.

RESULTS

Electron microscopy of tissue specimens fixed at 2 minutes (before mast cell activation) showed enhanced endocytic uptake of HRP in enterocytes of HRP-sensitized rats compared with ovalbumin-sensitized or saline-injected controls. At this time, HRP was distributed throughout epithelial cells and was already evident in the lamina propria. In contrast, HRP was restricted to the apical region of enterocytes in controls. At 30 minutes (after mast cell activation), in HRP-sensitized rats only, HRP was also located within tight junctions and the paracellular region between epithelial cells. Tissue conductance was increased in HRP-sensitized rats beginning 30 minutes after HRP addition and correlated with the overall flux of HRP across the tissue.

CONCLUSIONS

The results show that specific sensitization enhances the initial uptake and transcytosis of antigen across intestinal epithelium. Subsequent to activation of mast cells, antigen transport is further enhanced by penetration through the paracellular pathway.

How accurate is the recall of bowel habits in children with defaecation disorders?

The aim was to assess in children with defaecation disorders, the accuracy of recalled information as provided by the child and/or parents compared to diary information and to evaluate its effect on diagnostic grouping. In this prospective study, recalled information, obtained initially by a telephone interview, was compared with recorded information provided by a 4-week diary. Recalled and recorded data were compared using Kappa indices. Subsequently, children were assigned to three diagnostic groups: constipation, solitary encopresis and a rest group. Based on these diagnoses, the first two groups were allocated for laxative treatment. Analysis of recalled and recorded data was performed in 46 children (5-14 years). Most defaecation parameters showed fair agreement, only limited agreement occurred for frequency of soiling episodes. Identical clinical groups using the two methods were obtained in 63% of the children. Particularly, the assessment of large amounts of stool and the number of soiling episodes were responsible for the shift in the diagnostic groups. A total of 83% children were correctly allocated for treatment using recalled data.

Gastro-oesophageal reflux in children

Gastro-oesophageal reflux in children is different in several aspects from in adults. Pathophysiologically, 50% of reflux episodes are due to increased abdominal pressure which overcomes the lower oesophageal sphincter pressure. This pathophysiological abnormality disappears in children at the age of 1.5-2 years. Treatment is therefore different and aimed at thickening the gastric contents to inhibit reflux (Nutrition, Gaviscon, Algicon). The child is placed in the anti-Trendelburg position when asleep. No further investigation or intensification of treatment is necessary in young children under the age of 2 years unless complications are present. With complicated gastro-oesophageal reflux, treatment in children is comparable to that in adults; the effects of H2 antagonists and proton-pump inhibitors are identical. Long-term complications of gastro-oesophageal reflux are rare. In the near sudden death syndrome or acute life-threatening events in infants due to total sphincter relaxation aspiration is possible and should be prevented. Optimal treatment and monitoring are mandatory. In mentally handicapped children rumination is more prominent than gastro-oesophageal reflux. It is difficult to distinguish between vomiting, regurgitation and rumination. Treatment of oesophagitis might improve quality of life. When clear eosinophilic oesophagitis is observed food allergy should be considered and appropriately treated.

Randomised trial of biofeedback training for encopresis

AIMS

To evaluate biofeedback training in children with encopresis and the effect on psychosocial function.

DESIGN

Prospective controlled randomised study. PATIENT INTERVENTIONS: A multimodal treatment of six weeks. Children were randomised into two groups. Each group received dietary and toilet advice, enemas, oral laxatives, and anorectal manometry. One group also received five biofeedback training sessions.

MAIN OUTCOME MEASURES

Successful treatment was defined as less than two episodes of encopresis, regular bowel movements, and no laxatives. Psychosocial function after treatment was assessed using the Child Behaviour Checklist.

RESULTS

Children given laxatives and biofeedback training had higher success rates than those who received laxatives alone (39% v 19%) at the end of the intervention period. At 12 and 18 months, however, approximately 50% of children in each group were successfully treated. Abnormal behaviour scores were initially observed in 35% of children. Most children had improved behaviour scores six months after treatment. Children with an initial abnormal behaviour score who were successfully treated had a significant improvement in their behavioural profiles.

CONCLUSIONS

Biofeedback training had no additional effect on the success rate or behaviour scores. Psychosocial problems are present in a subgroup of children with encopresis. The relation between successful treatment and improvement in behavioural function supports the idea that encopresis has an aetiological role in the occurrence and maintenance of behavioural problems in children with encopresis.

[The relationship between intake of dietary fiber and chronic constipation in children]

OBJECTIVE

Evaluation of the feeding patterns of children with chronic constipation, in particular dietary fibres, energy and fluid intake and their influence on colonic transit time. In addition, the effect of dietary recommendations regarding fibres was assessed.

DESIGN

Prospective randomized study.

SETTING

Department of Paediatric Gastroenterology and Nutrition, Academic Medical Centre, Amsterdam, the Netherlands.

METHOD

Children with at least 2 months of complaints related to constipation were enrolled and both dietary intake and colonic transit time were evaluated. After dietary and laxative treatment, in some combined with biofeedback training, and a follow-up of 6 months, a randomized sample were again evaluated regarding their transit times and dietary patterns.

RESULTS

In 73 consecutive children mean fibre intake was the same as in healthy controls, although energy and fluid intake were lower. Colonic transit time was increased compared with healthy controls and no relationship was established between fibre intake and transit time. At 6 months no significant increase in mean fibre intake was observed and no relationship was found between either transit time and change in fibre intake or cure and change in fibre intake. In the cured patients no increase of their mean fibre intake could be observed.

CONCLUSION

The amount of dietary fibres played no pathogenic part in chronic constipation. Dietary advice did not change the mean fibre content of the diet. In addition, changes in fibre intake had no effect on colonic transit time or cure.

Celiac disease

With the increased use of antibodies to endomysium and gliadin, celiac disease is being diagnosed more frequently. Attention is now focused on diagnosing celiac disease with minor symptomatology and with a variety of severe symptoms, and diseases related to celiac disease are becoming more well known. New symptoms and diseases related to celiac disease are described. The relevance of antiendomysium and antigliadin antibodies in diagnosing celiac disease has become more established.

Colonic transit time in constipated children: does pediatric slow-transit constipation exist?

In adults, slow-transit constipation is a well-established form of constipation with abdominal pain and an empty rectum on examination. Marker studies in these patients, mainly women, show a markedly slowed transit time in all colonic segments. No studies in constipated children are available that assess the existence of slow-transit constipation. In a prospective study, a total of 94 referred constipated pediatric patients, 63 boys and 31 girls (median age, 8.0 years), underwent colonic-transit-time measurements using radioopaque markers to evaluate the pattern of transit. In addition, orocecal-transit-time measurements using the hydrogen breath (lactulose) test, anorectal manometry, and behavior studies using the Child Behavior Checklist were performed in all children. Based on the upper limit (mean + 2 SD) of total colonic transit time (CTT) in constipated children, we arbitrarily separated patients into two groups. Children with CTTs > 100 h were said to have pediatric slow-transit constipation (PSTC), while patients with CTTs < 100 h were said to have normal- or delayed-transit constipation (NDTC). In 94 constipated children, PSTC was found in 24 children; in 70 children, total CTT was < 100 h (NDTC). Total and segmental CTTs were significantly prolonged in PSTC (median, 189 h; range, 104.4-384) versus NDTC (median, 46.8 h; range, 3.6-99.4) hours. No significant differences were found in orocecal transit time. Significant clinical differences in children with PSTC versus those with NDTC existed regarding nighttime soiling (71 vs. 11%); daytime soiling episodes (14 vs. 7 each week, median), and nighttime soiling episodes (5 vs. 0 each week, median); absent urge to defecate (33 vs. 14%); and palpable abdominal (71 vs. 39%) and/or rectal (71 vs. 13%) masses. All manometric parameters were comparable in the two groups, except for a significantly lower maximal squeeze pressure with PSTC. Using the Child Behavior Checklist, both groups differed significantly from controls (26 and 43%, respectively), with no significant differences in behavior problems found between the NDTC and the PSTC groups. In conclusion, based on objective marker studies, our findings suggest the existence of pediatric slow-transit constipation. This entity can be recognized by clinical features, most importantly nighttime soiling and a palpable rectal mass. The probability of PSTC with both of these symptoms was 0.82; in the absence of these two symptoms, it was 0.07. It is of interest that CTTs in PSTC are comparable with CTTs in adults with slow-transit constipation, although the clinical presentation is clearly different. Further studies are needed to investigate whether the prolonged CTT characterizes a distinct form of constipation in children or is an epiphenomenon of the underlying constipation itself. The mechanisms responsible for the slow transit in these children and the appropriate therapeutic approach need to be studied.

Biofeedback training in treatment of childhood constipation: a randomised controlled study

BACKGROUND

Because abnormal defaecation dynamics, which can be modified by biofeedback, are considered to be the underlying problem in constipation, biofeedback training may be a useful treatment for constipation. This treatment has mainly been studied in uncontrolled trials. We evaluated defaecation dynamics and clinical outcome in chronically constipated children in a randomised study comparing conventional treatment and conventional treatment with biofeedback training.

METHODS

Patients, 5 to 16 years old, were referred to the Academic Medical Center in Amsterdam by general practitioners, school doctors, paediatricians, and psychiatrists. They had to fulfil at least two of four criteria for paediatric constipation and were included if they had been treated medically for at least one month before randomisation. Patients had a medical history, abdominal and rectal examination, and anorectal manometry at the start and end of the 6-week intervention period. The conventional group received laxative treatment with additional dietary advice, toilet training, and maintenance of a diary of bowel habits. The biofeedback group received the same conventional treatment and additionally five biofeedback training sessions. During the first 3 weeks, patients visited the outpatient clinic weekly; two subsequent visits were twice monthly.

FINDINGS

94 patients were randomised to conventional treatment (CT) and 98 to conventional treatment with additional biofeedback training (CT+BF). Normal defaecation dynamics increased in the CT group from 41% to 52% (not significant) and in the CT+BF group from 38% to 86% (p = 0.001). At 6 weeks, more patients in the CT+BF group showed normal defaecation dynamics, compared to the CT group (p < 0.001). This result was unaltered by controlling for baseline status in a logistic regression model. At 1 year, successful treatment (defaecation frequency > or = 3/week, soiling and/or encopresis < 2/month, and no laxatives) was accomplished in 59% of the CT and 50% of the CT+BF group (p = 0.24). The results were maintained after 1 1/2 years follow-up. No association was found between achievement of normal defaecation dynamics and clinical outcome.

INTERPRETATION

Additional biofeedback training compared to conventional therapy did not result in higher success rates in chronically constipated children. Furthermore, achievement of normal defaecation dynamics was not associated with success: abnormal defaecation dynamics seem not to play a crucial role in the pathogenesis of childhood constipation. Intensive conventional laxative treatment should remain the first choice in chronically constipated children.

Carbachol, but not forskolin, increases mucosal-to-serosal transport of intact protein in rat ileum in vitro

The effects of the secretagogues forskolin and carbachol on protein uptake in isolated ileum of rats were studied. The mucosal-to-serosal transport of horseradish peroxidase (HRP, mol mass 40 kDa) was measured in Ussing chambers, and afterwards tissues were processed for electron microscopy. In the absence of secretagogues, the flux of enzymatically active HRP was 5 pmol.cm-2.h-1 at a mucosal concentration of 10 microM. Electron micrographs showed vesicles filled with active HRP in enterocytes but no HRP activity in intercellular spaces. Forskolin decreased HRP activity in the cells. Carbachol increased the amount of HRP-filled vesicles in enterocytes and induced HRP filling in some intercellular spaces and tight junctions in the upper parts of the villi. The transepithelial flux of intact HRP increased more than 2.5-fold. This effect was suppressed by atropine. We conclude that cholinergic activation can increase the uptake of intact protein via endocytosis and the transepithelial passage by the induction of a diffusional paracellular pathway. We speculate that the increased transport of intact protein through the intestinal barrier may influence immunologic sensitization to food allergens.

Defaecation disorders in children, colonic transit time versus the Barr-score

It is still unclear how to evaluate the existence of faecal retention or impaction in children with defaecation disorders. To objectivate the presence and degree of constipation we measured segmental and total colonic transit times (CTT) using radio-opaque markers in 211 constipated children. On clinical grounds, patients (median age 8 years (5-14 years)) could be divided into three groups; constipation, isolated encopresis/soiling and recurrent abdominal pain. Barr-scores, a method for assessment of stool retention using plain abdominal radiographs, were obtained in the first 101 patients, for comparison with CTT measurements as to the clinical outcome. Of the children with constipation, 48% showed significantly prolonged total and segmental CTT. Surprisingly, 91% and 91%, respectively, of the encopresis/soiling and recurrent abdominal pain children had a total CTT within normal limits, suggesting that no motility disorder was present. Prolonged CTT through all segments, known as colonic inertia, was found in the constipation group only. Based on significant differences in clinical presentation, CTT and colonic transit patterns, encopresis/soiling children formed a separate entity among children with defaecation disorders, compared to children with constipation. Recurrent abdominal pain in children was in the great majority, not related to constipation. Barr-scores were poorly reproducible, with low inter- and intra-observer reliability. This is the first study which shows that clinical differences in constipated children are associated with different colonic transit patterns. The usefulness of CTT measurements lies in the objectivation of complaints and the discrimination of certain transit patterns. Conclusion. Abdominal radiographs, even when assessed with the Barr-score proved unreliable in diagnosing constipation.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential in vivo and in vitro intestinal permeability to lactulose and mannitol in animals and humans: a hypothesis

BACKGROUND/AIMS

Clinical interpretation of urinary recovery ratios of lactulose and mannitol is hampered by incomplete understanding of the mechanisms of transmucosal passage. The aim of this study was to compare in vivo and in vitro probe permeability.

METHODS

Stripped sheets of small intestine from rodents and human biopsy specimens were mounted in Ussing chambers, and mucosa-to-serosa fluxes of lactulose and mannitol were determined. Urinary recovery of orally applied probes was measured in rodents, cats, and humans.

RESULTS

In vitro lactulose/mannitol flux ratios were close to 0.8 in all species. Urinary recovery ratios differed between rodents and cats or humans; low ratios in cats and humans were due to high mannitol recovery.

CONCLUSIONS

Interspecies variation in urinary recovery of mannitol is caused by differences specific for the intact small intestines in vivo. Because hyperosmolality of villus tips in vivo varies, being highest in humans and cats as a result of vascular countercurrent multiplication, it is hypothesized that the high urinary recovery of mannitol in these species is caused by solvent drag through pores that allow the passage of mannitol but not of lactulose. Therefore, the lactulose/mannitol ratio is primarily a standard for the normal functioning of villus epithelial cells in metabolite absorption and for normal villus blood flow.

The role of endoscopic retrograde cholangiopancreatography in cholestatic infants

Conjugated hyperbilirubinemia in infants is a serious problem, and one that requires further investigation. Early differentiation between extrahepatic and intrahepatic causes of cholestasis is essential for the proper management of cholestasis in infancy. A successful outcome in patients with extrahepatic biliary atresia is significantly influenced by the age at which the Kasai procedure (hepatoportoenterostomy) is performed. However, extensive diagnostic workup may fail to distinguish definitively between intrahepatic and extrahepatic disease, and exploratory laparotomy and intraoperative cholangiography are sometimes necessary to exclude extrahepatic disease. In the last four years, 20 cholestatic infants were referred to our center in whom no definite diagnosis was possible, despite thorough diagnostic evaluation. In an attempt to increase the accuracy of our diagnostic work-up, we performed ERCP during the anesthetic period planned for liver biopsy. We succeeded in performing ERCP in 18 children (90%); in five of them (28%), patent bile ducts were demonstrated, and unnecessary laparotomy could be avoided. In four patients (22.2%), a stricture of the common bile duct was seen, in three combined with a choledochal cyst. In two patients (11.1%), only the common bile duct and gallbladder were opacified. Five of seven patients in whom only the pancreatic duct was visualized had complete occlusion of the extrahepatic biliary ducts at surgery. The other two patients did not undergo surgery because initially no signs of extrahepatic obstruction were found in their biopsy. One of these patients deteriorated and needed a liver transplant one year later. This patient proved to have extrahepatic biliary atresia. No severe complications of ERCP were observed; only sporadically, a slight elevation of pancreatic enzymes was noted. We advocate this procedure in the workup of infants with unexplained conjugated hyperbilirubinemia. Anomalies in the biliary tree can be demonstrated, and when patent bile ducts are found, laparotomy can be avoided.

Is encopresis always the result of constipation?

Encopresis is often the result of chronic constipation in the majority of paediatric patients. In clinical practice, however, encopresis is also seen without constipation and it is unknown whether these two clinical variants are based on similar or different pathophysiological mechanisms, requiring different therapeutic approaches. We analysed clinical symptoms, colonic transit time (CTT), orocaecal transit time (OCTT), anorectal manometric profiles, and behavioural scores. Patients were divided into two groups, one consisted of 111 children with paediatric constipation, and another group of 50 children with encopresis and/or soiling without constipation. Significant clinical differences in children with encopresis/soiling existed compared with children with paediatric constipation regarding: bowel movements per week, the number of daytime soiling episodes, the presence of night time soiling, the presence and number of encopresis episodes, normal stools, pain during defecation, abdominal pain, and good appetite. Total and segmental CTT were significantly prolonged in paediatric constipation compared with encopresis/soiling, 62.4 (3.6-384) and 40.2 (10.8-104.4) hours, respectively. No significant differences were found in OCTT. Among the two groups, all manometric parameters were comparable, except for a significantly higher threshold of sensation in children with paediatric constipation. The defecation dynamics were abnormal in 59% and 46% in paediatric constipation and encopresis/soiling, respectively, and were significantly different from controls. Using the child behaviour checklist no significant differences were found when comparing children with paediatric constipation and encopresis/soiling, while both patient groups differed significantly from controls. In conclusion, our findings support the concept of the existence of encopresis as a distinct entity in children with defecation disorders. Identification of such children is based on clinical symptoms, that is, normal defecation frequency, absence of abdominal or rectal palpable mass, in combination with normal marker studies and normal anal manometric threshold of sensation, Thus, encopresis is not always the result of constipation and can be the only clinical presentation of a defecation disorder.

Symptomatic gastroesophageal reflux: diagnosis with ultrasound

Ultrasound is a new test proven to be sensitive in the demonstration of gastroesophageal reflux (GER). Following reflux seen with ultrasound various symptoms can be observed in physiological circumstances, and thereby a causal relationship between reflux and these symptoms can be observed in physiological circumstances, and thereby a causal relationship between reflux and these symptoms can be proven. We performed a study in 220 children suspected of GER to determine the incidence of sonographically demonstrated "symptomatic reflux" in different clinical groups: children with (1) vomiting only, (2) respiratory symptoms, (3) attack-like symptoms, and (4) pain and irritability. Overall, GER was demonstrated in 78% of all 209 children in whom technically satisfactory studies could be performed. This reflux was associated with symptoms in 32% of the cases. Symptomatic reflux was most frequent in group 3, which included children investigated for near-miss sudden infant death syndrome. The symptoms that were noted most frequently were vomiting, motor unrest, coughing, and wheezing. Apnea, bradycardia and attacks of unusual posturing could incidentally be related to reflux. Ultrasound is a cheap, simple, noninvasive, and physiological test to show clinically significant reflux.