Gastric emptying and orocecal transit in portal hypertension and end-stage chronic liver disease

Our aim was to evaluate gastric emptying and orocecal transit in patients with end-stage liver disease and portal hypertension undergoing evaluation for liver transplantation. Although gastric emptying half-times for both liquid and solid emptying were similar in patients with chronic liver disease and control subjects, orocecal transit, as measured by a scintigraphic technique, was significantly prolonged in the patients with liver disease (transit time, minutes, mean +/- SEM, patients versus controls: 127 +/- 10.5 versus 80 +/- 9.5, P < .003). Serum levels of progesterone and estradiol were similar in patients and controls. We conclude that small intestinal transit is delayed in patients with advanced liver disease and portal hypertension and may contribute to gastrointestinal symptoms and promote sepsis of enteric origin in this patient population.

Luminal short-chain fatty acids and postresection intestinal adaptation

BACKGROUND

Short-chain fatty acids (SCFAs) reportedly have a trophic effect on the small intestine. However, it is unclear if this is a local or primarily systemic effect. Loss of the ileocolonic junction (ICJ) may result in increased SCFAs and bacteria in the small intestine from colonic reflux. Our aim was to evaluate the effect of bypass of the ICJ on intestinal SCFA content and postresection adaptation.

METHODS

Thirty dogs were studied: transection control (TC, n = 10), distal resection of 50% intestine (DR, n = 10), and distal resection with bypass of ICJ (DRBP, n = 10). Animals were killed at 4 and 12 weeks. Luminal SCFAs and bacteria and adaptation of the small intestine were evaluated.

RESULTS

Caloric intake was significantly less in the two resected groups (67 +/- 3 DR and 63 +/- 3, DRBP vs 78 +/- 5 kcal/kg/d TC, p < .05). Body weight and albumin levels were decreased at 12 weeks but were similar between the resected groups (81% +/- 3% and 74% +/- 6% initial and 1.9 +/- 0.1 and 2.1 +/- 0.2 g/dL, DR and DRBP, respectively). Steatorrhea was present for 12 weeks after resection and was greater after DRBP (14.2% +/- 3.8% vs 8.6% +/- 1.9% at 4 weeks and 13.6% +/- 2.5% vs 6.7% +/- 0.6% at 12 weeks, p < .05). Bypassed animals had elevated intraluminal SCFA content (3126 +/- 1094 vs 1791 +/- 538 DR and 1600 +/- 446 micrograms/mL TC, p < .05) and anaerobic bacterial counts (100% vs 50% and 44%, respectively). Tissue inflammation and myeloperoxidase activity were similar. Small intestinal length (174 +/- 10 and 180 +/- 10 cm) and circumference (5.2 +/- 0.4 and 5.2 +/- 0.3 cm) increased to a similar extent in both resected groups at 12 weeks. Thickness of mucosa (1939 +/- 162 vs 1662 +/- 162 microns) and muscle (865 +/- 45 vs 978 +/- 79 microns) layers were similar after DR and DRBP.

CONCLUSION

(1) Bypass of the ICJ after distal resection results in increased growth of anaerobic bacteria and luminal SCFA and is associated with more marked steatorrhea. (2) Bypass of the ICJ does not influence structural adaptation of the small intestine. (3) These findings do not support a local trophic effect for SCFA.

Smooth muscle adaptation after intestinal transection and resection

Changes in motor function occur in the intestinal remnant after intestinal resection. Smooth muscle adaptation also occurs, particularly after extensive resection. The time course of these changes and their interrelationship are unclear. Our aim was to evaluate changes in canine smooth muscle structure and function during intestinal adaptation after transection and resection. Twenty-five dogs underwent either transection (N = 10), 50% distal resection (N = 10), or 50% proximal resection (N = 5). Thickness and length of the circular (CM) and longitudinal (LM) muscle layers were measured four and 12 weeks after resection. In vitro length-tension properties and response to a cholinergic agonist were studied in mid-jejunum and mid-ileum. Transection alone caused increased CM length in the jejunum proximal to the transection but did not affect LM length or muscle thickness. A 50% resection resulted in increased length of CM throughout the intestine and thickening of CM and LM near the anastomosis. Active tension of jejunal CM increased transiently four weeks after resection. Active tension in jejunal LM was decreased 12 weeks after transection and resection. Sensitivity of CM to carbachol was similar after transection and resection. It is concluded that: (1) Structural adaptation of both circular and longitudinal muscle occurs after intestinal resection. (2) This process is influenced by the site of the intestinal remnant. (3) Only minor and transient changes occur in smooth muscle function after resection. (4) Factors other than muscle adaptation are likely involved in the changes in motor function seen following massive bowel resection.

Gastrointestinal dysfunction in Parkinson's disease

Gastrointestinal dysfunction is common and clinically important in patients with PD. Evidence continues to accumulate to indicate that these symptoms reflect, for the most part, the direct involvement of the gastrointestinal tract by the PD process. Gastrointestinal symptomatology may arise not only as a consequence of the effects of PD on skeletal muscles in the oropharynx, anorectum, and pelvic floor but also through the direct involvement of the autonomic and enteric nervous systems in the PD process. While many aspects of gastrointestinal dysfunction in PD continue to be delineated, therapeutic approaches to gut symptoms in this common disorder remain in their infancy. Gut involvement in PD can be seen to serve as a paradigm for gut-CNS interactions. The recent demonstration of neuropathologic abnormalities in the enteric nervous system analogous to those regarded as pathognomonic of the parkinsonian process in the CNS suggests that the enteric and central nervous systems may demonstrate parallel pathologic changes in a number of disease processes previously regarded as confined to the central and somatic nervous systems. In this way, the enteric nervous system may well serve as a more accessible "window" to a variety of degenerative neurologic disorders. With respect to PD itself, we can begin to relate both the neurologic and gastrointestinal manifestations of this disorder to defects at a number of levels (Table 1).

An evaluation of an ambulatory manometry system in assessment of antroduodenal motor activity

While abnormalities in antroduodenal motor function have been documented in both organic and "functional" disorders, controversy surrounds the ideal manometric technique. We sought, therefore, to evaluate a digital solid-state ambulatory system. Sixteen normal volunteers underwent 24-hr recordings of antroduodenal motility. Following catheter placement, a standardized meal was ingested in the laboratory; thereafter, subjects were ambulatory and assumed normal diet and activities. The system was well tolerated; subjects reported that it did not affect their usual activities. Migrating motor complex (MMC) activity was identified in each subject (mean frequency: 4.1 MMCs/24 hr, range 1-8); on average 1.9 (range 0-4, frequency 0.1/hr) occurred while awake and 2.1 (range 0-5, 0.3/hr, P < 0.05 vs awake) during sleep. The fed response was evaluated by calculating a motility index (MI) at 30-min intervals from 30 min before to 120 min following meal ingestion. Postprandially, MI was maximal during the first 30 min following meal ingestion: MI (mean +/- SD) 30 min before vs 30 min after meal in the antrum: 4.16 +/- 1.42 vs 5.33 +/- 0.72 (P < 0.05), duodenum: 4.04 +/- 0.80 vs 4.57 +/- 0.47 (P < 0.05), respectively. None of the other postprandial intervals were significantly different from baseline. There was no significant difference in MI between the standard and ad libitum meals. Retrograde catheter migration (mean 5.6, range 1-10 cm) occurred in relation to all meals: as a consequence, antral recordings were lost following 60% of all meals, thereby limiting meaningful analysis of the antral fed response. We conclude, firstly, that while an ambulatory antroduodenal manometry system is well tolerated and reliably records duodenal motility, postprandial catheter migration limits antral recordings, and, secondly, that a motility index calculated during the first 30 min following an ad libitum meal accurately reflects the fed motor response.

Time course of adaptive regulatory peptide changes following massive small bowel resection in the dog

Basal and postprandial concentrations of gastrointestinal hormones were measured in 12 dogs before and at one and three months after a 75% small bowel resection. Five animals were studied again at six months. Concentrations of enteric hormones and neuropeptides, measured in the proximal jejunum and distal ileum adjacent to the anastomotic site at the time of euthanasia, were compared with concentrations in control tissues taken from each animal at the time of resection. Increased basal and postprandial levels of gastrin (P < 0.05), cholecystokinin (CCK, P < 0.05), glucose-dependent insulinotropic peptide (GIP, P < 0.01), peptide YY (PYY, P < 0.001), and enteroglucagon (P < 0.001), were seen at one month after small bowel resection. In contrast, no significant changes were seen in concentrations of secretin, motilin, neurotensin, somatostatin, PP, or glucagon. Concentrations of enteroglucagon, GIP, and PYY remained high throughout the six-month study period. In contrast, gastrin and CCK had normalized by three months. Thus, only enteroglucagon, PYY, and GIP showed sustained elevations following enterectomy; the gastrin and CCK changes were transient. Following enterectomy, concentrations of vasoactive intestinal polypeptide (VIP) were reduced by about 50% in mucosal (P < 0.001) and muscle (P < 0.05) layers of proximal and distal gut. In contrast, calcitonin gene-related peptide (CGRP) was increased by about twofold in jejunal and ileal mucosa (P < 0.05), and CGRP elevations were even more marked in the muscle layers (P < 0.001). Somatostatin and neuropeptide Y (NPY) concentrations were similar to controls in all areas except for a small decrease in NPY in ileal mucosa (P < 0.05). These findings suggest that the increased motilin and PP concentrations previously reported after bowel resection in man are more likely to reflect underlying inflammatory bowel disease rather than enterectomy. The normalization of hypergastrinemia explains why the increased acid secretion after small bowel resection is transient. These results provide evidence for independent secretory control of enteroglucagon and PYY, which are both products of intestinal L cells. In addition, these studies reveal marked changes in enteric neuropeptide concentrations following bowel resection. VIP, which is thought to be a major inhibitory transmitter in the gut, is markedly reduced, while CGRP, which is mainly localized in sensory afferent fibers, is increased. These major neuropeptide changes are likely to be of importance in the adaptive responses to massive small bowel resection.

Gastric and small intestinal motility in health and disease

Although symptoms possibly related to motor dysfunction appear to be common, primary disorders of the foregut motor apparatus, defined on the basis of a discrete myoneural pathology, are notably rare. This phenomenon may as much reflect the relatively primitive nature of diagnostic methods as the true rarity of such disorders. Although diagnostic methodologies increase in sophistication and availability, their clinical impact has been limited by an imperfect relationship between symptoms and dysfunction and by a relatively poor ability of such tests to predict response to available therapeutic strategies. An ever-increasing understanding of the complex, often interrelated motor and sensory phenomena that contribute to symptoms, together with the development of consensus on the use and interpretation of motility tests and the more widespread application of sophisticated histologic, immunologic, biochemical, and molecular biologic methodologies to the study of these disorders, should lead, in the years to come, to much needed progress in this area.

Nonulcer dyspepsia: pathophysiology update

The condition remains poorly defined-it may represent several disorders that share symptoms. The search for a cause is shifting from infection, inflammation, and acid/peptic mucosal damage to dysmotility and CNS dysfunction.

Effect of extent of resection on intestinal muscle adaptation

The response of intestinal muscle to resection has received less attention than mucosal adaptation but may be important in relation to altered motility and improved intestinal absorption. Our aim was to determine the effect of extent of resection on intestinal muscle adaptation. Distal resections of 25% (n = 5), 50% (n = 5), and 75% (n = 5) of the intestine were performed. Transverse intestinal sections were taken at resection and 12 weeks later to evaluate changes in mucosa and circular and longitudinal muscle thickness. Muscle cell number and size and muscle length were also measured. Mucosal thickness increased (P < 0.05) after all resections, (1007 +/- 253 microns vs 1259 +/- 181 microns, 25%; 1019 +/- 191 microns vs 1366 +/- 293 microns, 50%; and 927 +/- 88 microns vs 1432 +/- 213 microns, 75%). Longitudinal muscle thickness (169 +/- 35 microns vs 254 +/- 45 microns, 50%; 207 +/- 71 microns vs 353 +/- 103 microns, 75%) and length (180 +/- 10 cm vs 203 +/- 16 cm, 50%; 90 +/- 16 cm vs 110 +/- 21 cm, 75%) increased (P < 0.05) following 50% and 75% resections but not after a 25% resection. Circular muscle length increased after 75% resection alone (4.4 +/- 0.2 cm vs 5.8 +/- 0.4 cm, P < 0.05). There was no significant change in circular muscle thickness after any resection. Muscle cell size and number per unit area were unchanged in all groups. We concluded that: (1) Intestinal muscle adapts after intestinal resection and this response is related to the extent of resection; in contrast, mucosal adaptation was evident following even the least extensive resection. (2) Increased thickness and length of the longitudinal muscle layer are the most prominent changes. (3) This increased muscle thickness results from hyperplasia rather than hypertrophy.

Smooth muscle contractility after intestinal resection

Intestinal resection is followed by structural and functional adaptation of the remnant, including motor adaptation. Since changes also occur in intestinal smooth muscle, our aim was to determine whether changes in motor function are related to changes in smooth muscle contractility. Eighteen dogs underwent transection alone (GPI, n=6), 50% distal resection (GP II, n = 6) and 50% distal resection with jejunocolostomy (GP III, n = 6). Histologic measurements and length-tension studies with response to carbachol were made at 12 weeks. Longitudinal muscle (LM) length tended to increase in the resected animals but not significantly (174 +/- 23 and 180 +/- 23 vs 156 +/- 16 cm, GP II, GP III, and GP I, respectively). Circular muscle (CM) length was similar in all three groups (8.2 +/- 0.9 and 7.9 +/- 0.6 vs 7.5 +/- 0.6 cm). Both CM and LM tended to be thicker in the resected groups (CM: 660 +/- 163 and 733 +/- 139 vs 569 +/- 199 micron; LM: 213 +/- 77 and 246 +/- 76 vs 220 +/- 104 micron, GP II, GP III, and GP I, respectively, NS). Length-tension relationships for both CM and LM were similar in all three groups. The length (Lo) at which maximal active tension (To) was achieved was 130-140% initially in both LM and CM. Passive tension at Lo and the response to cholinergic stimulation were similar in all three groups. There were no significant differences in absolute active and total tension generated or force/cm2. The carbachol dose responses were similar with the maximal active tension occurring at 10(-4) M carbachol. The ED50 was greater in CM than in LM (P < 0.05 for transection animals). The ED50 was lower after resection and bypass (P < 0.05 GP III vs Gp I). There were no significant differences in in vitro smooth muscle length tension relationships or the response to cholinergic stimuli of jejunum 12 weeks after resection with or without bypass of the ICJ. Thus, any changes in motor adaptation during this period are related to earlier transient effects or other factors.

Cricopharyngeal dysfunction in Parkinson's disease: role in dysphagia and response to myotomy

We report five patients with Parkinson's disease and dysphagia who were found, by radiological and manometric evaluation, to have evidence of cricopharyngeal dysfunction, which included the presence of a Zenker's diverticulum in two. Cricopharyngeal myotomy was performed in four patients with excellent and sustained improvement in swallowing. We conclude that cricopharyngeal function should be carefully evaluated in patients with Parkinson's disease and dysphagia and that surgical treatment should be considered in appropriate cases.

An examination of the reliability of reported stool frequency in the diagnosis of idiopathic constipation

OBJECTIVES

To investigate the reliability of reported stool frequency in the diagnosis of constipation.

METHODS

Our criterion for the diagnosis of idiopathic constipation was < or = 3 stools per week for > or = 6 months. Subjects who believed that they met this criterion were invited to participate. Daily stool frequency was recorded over a 4-wk period, and all stools were weighed during the final week. A colon transit study and anorectal manometry were performed at the beginning and at the end of the study.

RESULTS

On review of stool diaries from 45 subjects who described chronic constipation and who completed the 4-wk study, only 22 (49%) actually satisfied our criterion for idiopathic constipation. The remaining 23 (51%) subjects, although describing constipation, had, on average, 6 stools/wk. A history of psychiatric illness was 5 times more frequent among those whose bowel symptoms correlated poorly with objective measures. Measures of difficult defecation were similar in the two groups. Mean colon transit time was significantly longer and correlated closely with stool weight only in subjects who truly were constipated (p < 0.05). Anorectal manometry was not helpful in discriminating between those who satisfied our criterion for constipation and those who did not.

CONCLUSIONS

Defining constipation on the basis of a patient's reported stool frequency may prove misleading; the diagnosis of idiopathic constipation should be supported by the use of stool diaries and a colon transit study.

Effects of psyllium therapy on stool characteristics, colon transit and anorectal function in chronic idiopathic constipation

BACKGROUND

Psyllium is widely used in the symptomatic therapy of constipation. Its effects on colonic function and their correlation with symptomatic response have not been defined.

METHODS

After a 4-week baseline, placebo, run-in phase, 22 subjects with idiopathic constipation confirmed by prospectively administered stool diaries were randomly assigned to receive either psyllium (5 g b.d., 11 patients) or placebo (11 patients) for 8 weeks, followed by another 4-week wash-out, placebo phase. A colon transit study and anorectal manometry were performed at the beginning and at the end of each study phase. Subjects recorded, in diaries, their daily stool frequency, difficulty with defecation and weekly stool weight.

RESULTS

Stool frequency increased significantly after 8 weeks of psyllium treatment (3.8 +/- 0.4 vs. 2.9 +/- 0.1 stools/week, P < 0.05) as did stool weight (665.3 +/- 95.8 g vs. 405.2 +/- 75.9 g, P < 0.05). Subjects also reported an improvement in stool consistency (stool consistency score: 3.2 +/- 0.2 vs. 3.8 +/- 0.2, P < 0.05) and pain on defecation (pain score: 2.0 +/- 0.4 vs. 2.6 +/- 0.5, P < 0.05) on psyllium. Colon transit and anorectal manometry parameters were unchanged on psyllium. Subjects treated with placebo did not show any change in either subjective or objective measures of constipation.

CONCLUSIONS

Psyllium increases stool frequency and weight and improves stool consistency in idiopathic constipation. These effects are not associated with significant changes in either colonic or rectal motor function. We suggest that the beneficial effects of psyllium in constipation are primarily related to a facilitation of the defecatory process.

Gastrointestinal motility testing--a personal perspective

The role of motility tests in the evaluation of some common disorders in which motility has been assumed to play a role is reviewed. Three separate areas, non-cardiac chest pain, constipation and the irritable bowel syndrome are discussed. In each area, considerable difficulty in the clinical definition of these disorders persists and presents a major obstacle to the evaluation of diagnostic tests. With regard to non-cardiac chest pain, it is apparent that gastro-oesophageal reflux and sensory/perception abnormalities, rather than dysmotility, are the predominant factors, and investigations should take account of this. While studies of colonic and small intestinal motility have demonstrated various abnormal patterns in patients described as suffering from the irritable bowel syndrome, the specificity of any of these motor 'abnormalities' remains uncertain, and manometry cannot be recommended as a diagnostic tool in this context. Considerable advances have been made in our understanding of gut motor physiology and in our ability to accurately record motor function in man, the basic pathophysiology of many 'functional' gut syndromes remains unclear, and the role of dysmotility, in particular, poorly defined.

Surgical approach to short-bowel syndrome. Experience in a population of 160 patients

OBJECTIVE

The authors reviewed their experience with short-bowel syndrome to define the surgical approach to this problem in 160 patients.

METHODS

Forty-eight adults and 112 children were evaluated over a 15-year period.

RESULTS

Seventy-one patients (44%) adapted to resection and took enteral nutrition alone. Forty-four patients (28%) were supported by parenteral nutrition (PN). Forty-five patients (28%) have had 49 surgical procedures. Fifteen patients with adequate intestinal length (> 120 cm in adults) but dilated dysfunctional bowel underwent stricturoplasty (n = 4) or tapering (n = 11). Thirteen patients (87%) demonstrated clinical improvement. Fourteen patients with shorter remnants (90-120 cm) and rapid transit time received an artificial valve (n = 2) or a reversed segment (n = 1). All patients' conditions improved initially, but the reversed segment was revised or taken down. Fourteen patients with short remnants and dilated bowel underwent intestinal lengthening. Twelve patients' conditions improved (86%), one underwent transplantation, and one died. Sixteen patients with very short remnants (< 60 cm) and complications of PN underwent solitary intestine (n = 4) or combined liver-intestinal transplantation (n = 13). One-year graft survival was 65%. There have been five deaths.

CONCLUSIONS

The surgical approach to short-bowel syndrome depends on the patient's age, remnant length and caliber, intestinal function, and PN-related complications. Nontransplant procedures have a role in the treatment of selected patients. Intestinal transplantation is emerging as a potential therapy for patients with significant PN-related complications.

Dopaminergic defect of enteric nervous system in Parkinson's disease patients with chronic constipation

Clinical studies suggest that gut disorders are common in Parkinson's disease, but the morphological basis is unknown. Depletion of dopamine-containing neurons in the central nervous system is a basic defect in Parkinson's disease. We compared colonic tissue from 11 patients with advanced Parkinson's disease, 17 with adenocarcinoma (normal tissue was studied), and five who underwent colectomy for severe constipation. Immunohistochemistry was used to stain myenteric and submucosal neurons for dopamine, tyrosine hydroxylase, and vasoactive intestinal polypeptide (VIP). Each class of neurons was quantified as a percentage of the total neuronal population stained for the marker protein gene product 9.5. Nine of the 11 Parkinson's disease patients had substantially fewer dopaminergic myenteric neurons than the other subjects (mean 0.4 [SE 0.2] vs 6.9 [2.3] in controls and 5.7 [2.0] in constipated subjects). There was very little difference between the groups in numbers of tyrosine-hydroxylase and VIP neurons. Two Parkinson's disease patients had similar distributions of all types of neurons, including dopaminergic myenteric neurons, to the controls. High-performance liquid chromatography showed lower levels of dopamine in the muscularis externa (but not mucosa) in four Parkinson's disease patients than in four controls (7.3 [5.1] vs 24.2 [4.6] nmol per g protein), but levels of dopamine metabolites were similar in the two groups. The identification of this defect of dopaminergic neurons in the enteric nervous system in Parkinson's disease may lead to better treatment of colorectal dysfunction in this disease.

Anorectal function in fluctuating (on-off) Parkinson's disease: evaluation by combined anorectal manometry and electromyography

Anorectal dysfunction and constipation are well recognized in Parkinson's disease and may reflect the direct involvement of the gastrointestinal tract by the primary Parkinson's disease process. We hypothesized, therefore, that anorectal function would alter in parallel with fluctuations in motor function related to on- and off-periods in Parkinson's disease, and employed combined anorectal manometry and electromyography to investigate anorectal function during both on- and off-periods in patients with Parkinson's disease. Manometric recordings revealed a deterioration in voluntary sphincter squeeze during off-periods (squeeze index, on versus off, mean +/- SEM: 46.4 +/- 11.1 versus 29.6 +/- 7.9 mm Hg, p < 0.05); correspondingly, simultaneous electromyographic (EMG) recordings showed poor recruitment of external anal sphincter and puborectalis muscles during off-periods. A hypercontractile ("paradoxical") rectosphincteric reflex response occurred during both on- and off-periods, and was associated with an increase in EMG activity in the external sphincter and/or the puborectalis muscle. These changes in manometric and EMG parameters paralleled changes in overall motor function. These findings provide further support for the involvement of the pelvic floor musculature in the Parkinson's disease process and also provide EMG correlates for some of the manometric abnormalities described in Parkinson's disease.