Sensory and biomechanical responses to distension of the normal human rectum and sigmoid colon.

BACKGROUND: Visceral pain is a major clinical problem. The aim of the present study was to compare the pain and biomechanical responses to standardized distension of the human colon. METHODS: The relation between pain intensity and pressure, cross-sectional area (CSA) and tension-strain relations of the rectum and sigmoid colon were studied in 11 normal subjects following standardized distension using impedance planimetry. The bag was inflated stepwise with pressures up to 6 kPa. The subjects, who were blinded for the distension procedure, rated their pain intensity using an aggregate visual analogue score (VAS) combining the intensity of the feeling of air, urge to defecate and pain. RESULTS: The distensions produced an initial rapid increase in CSA followed by a phase of slow increase until a steady state CSA was reached after 0.5-1 min. Several phasic contractions (observed as short-term decreases in the CSA) were recorded in the rectum from the end of the rapid phase to the end of distension at pressures from 1 to 5 kPa. The CSA in the rectum and sigmoid colon was 3,706 +/- 426 mm(2) and 2,305 +/- 426 mm(2) at the maximum bag pressure of 6 kPa (F = 52.4, p < 0.001). The tension-strain relation did not differ between the normal rectum and sigmoid colon. The VAS score for every modality (air, defecation and pain) revealed an increase in intensity as a function of pressure. The VAS score in the rectum and the sigmoid colon as a function of tension and strain did not show any differences. CONCLUSIONS: The biomechanical properties in the sigmoid colon and rectum were alike. For a given wall tension and circumferential strain the sensibility seems equal in the rectum and the sigmoid colon. The observed difference in perception between the two segments was related to the greater CSA in the rectum.     

Twenty-four hour recordings of colonic motility in patients with diverticular disease

INTRODUCTION: Diverticular disease of the colon is one of the most common pathologic entities in western countries. Although altered motility of the large bowel is commonly believed to be one of the major pathophysiologic mechanisms, no convincing evidence has been reported yet. In fact, only a few conflicting studies concerning distal colonic motility (with no information on forceful propulsive activity) are available in the literature. PURPOSE: The purpose of the present study was to investigate basal and stimulated (postprandial) colonic motility from the transverse (not affected), descending, and sigmoid colon in patients with diverticular disease, together with detection of high-amplitude propagated contractions (mass movements). Motility data from patients were compared with those obtained in healthy control subjects. METHODS: Ten patients and 16 control subjects of both sexes were recruited for the study. In all subjects, colonic motility was recorded for a 24-hour period by a colonoscopically positioned manometric catheter. Two 1000-kcal mixed meals were served during the study. RESULTS: Compared with control subjects, patients with diverticular disease displayed significantly increased amounts of motility in the affected segments; the response to a physiologic stimulus (meal) was also abnormal in the patients' group. Diverticular disease patients also had a significant increase of forceful propulsive activity compared with control subjects (average = 10.3±2.7/subject/day high-amplitude propagated contractions for patients and 5.5±0.8/subject/day for control subjects;P=0.051); interestingly, about 20 percent of such activity was abnormal, being propagated in a retrograde fashion. CONCLUSIONS: We concluded that patients with diverticular disease of the colon have abnormal motor and propulsive activities of the large bowel, which are confined to the affected segments.During the period this study was performed, Dr. Battaglia was on leave from the Department of Clinical Pathophysiology, University of Torino Medical School.     

Biomechanical characteristics of the human esophagus

Biochemechanical wall properties of the human esophagus were studied. A probe, with a balloon designed for simultaneous measurement of cross-sectional area and intraluminal pressure, was placed in the esophagus 30 cm from the incisors. Tone was not detected before inflation of the balloon. When the balloon was inflated stepwise with pressures up to 40 cm H₂O (30.7 mm Hg), measurement of cross-sectional area allowed calculation of distensibility and circumferential wall tension. Balloon cross-sectional area increased linearly with increased balloon pressure. Balloon distension induced contractions, both proximal to the balloon and at the site of distension, at a balloon pressure of about 15 cm H₂O (11.5 mm Hg). The cross-sectional area for the threshold for distension induced contractions was 153±12 mm² (diameter 14 mm). At the onset of these contractions, the contraction force was 15–20 cm H₂O (11.5–15.3 mm Hg) and it increased to 47–58 cm H₂O (36.1–44 mm Hg) at a balloon pressure of 20–40 cm H₂O (15.3–30.7 mm Hg). Circumferential wall tension increased with increasing intraluminal pressure in an almost exponential manner. The pressure elastic modulus increased steeply at lower balloon pressures (10–20 cm H₂O) (7.7–11.5 mm Hg), but at higher balloon pressures (20–40 cm H₂O) (15.3–30.7 mm Hg) this increase was less. The circumferential wall tension and wall stiffness of the human esophagus increased with increasing balloon pressure and cross-sectional area. When a threshold is reached, distension induced contractions both proximal and distal to the balloon and at the distension site.This work was supported by a National Institutes of Health grant DK 11242.     

Effect of eating on colonic motility and transit in patients with functional diarrhea. Simultaneous scintigraphic and manometric evaluations

The aim of this study was to correlate colonic motility with transit in 8 patients with functional diarrhea compared to 12 healthy subjects. Intraluminal pressure was measured with perfused catheter ports in the transverse colon, splenic flexure, and descending and sigmoid colons. Transit of the luminal contents was measured by following the movement of 99mTC-diethylenetriaminepentaacetic acid instilled as a bolus in the splenic flexure. In patients with diarrhea, the intraluminal marker moved in and out of the transverse and sigmoid colon regions of interest during fasting, unlike healthy subjects, in whom the marker remained in the splenic flexure. After eating, radioactivity immediately increased in both the transverse and sigmoid colons in healthy subjects. In the patients with diarrhea, eating did not alter the marker movement into the different regions of the colon compared with fasting. Within 100 minutes of eating, the intraluminal marker almost disappeared from the regions of interest in patients with diarrhea. Postprandial colonic nonpropagating contractions increased in each region of the colon in healthy subjects; there was only a small postprandial increase in colonic motility in patients with diarrhea. However, the numbers of fasting and postprandial propagating contractions were increased in patients with diarrhea compared with healthy subjects (P less than 0.02). Each propagating contraction moved more tracer in patients with diarrhea than in healthy subjects (P less than 0.05). These studies suggest that (a) in patients with diarrhea, the fluctuation of marker in both transverse and sigmoid colons during the fasting and postprandial periods is associated with decreased nonsegmenting contractions and frequent propagating contractions; and (b) in healthy subjects, the intraluminal marker moved after eating because of a pressure gradient caused by nonpropagating contractions.     

Colorectal Motility Induction by Sacral Nerve Electrostimulation in a Canine Model

PURPOSE: This study investigated the role of the sacral nerves in the mechanism of defecation using adult mongrel dogs. The possibility of designing a colonic pacemaker as a new therapeutic device to treat defecation disturbances, such as fecal incontinence and severe constipation, is also discussed. METHODS: Colorectal motility during spontaneous defecation was monitored with force strain-gauge transducers implanted in the proximal, distal, and sigmoid colon, rectum, and internal anal sphincter. Under general anesthesia, the sacral nerve was stimulated electrically, and the colorectal motility response was examined. RESULTS: During spontaneous defecation, three characteristic motility patterns were observed: 1) giant migrating contractions of the colon were propagated to the rectum or anus; 2) the rectum relaxed before the giant migrating contractions were propagated; and 3) the internal anal sphincter was relaxed during the propagation of the giant migrating contraction. Sacral nerve stimulation elicited the following three unique responses: 1) contractile movements were propagated from the distal colon to the rectum; 2) a relaxation response was noted in the rectum; and 3) the internal anal sphincter exhibited a relaxation response. The duration and propagation velocity of the contractile responses and the duration of relaxation responses elicited by electrical stimulation of the sacral nerve were similar to those that occurred during spontaneous defecation, but their amplitudes were smaller. CONCLUSION: The coordinated processes of the colon and anorectum during defecation were affected by the sacral nerves. This suggests that it is possible to design a colonic pacemaker to control lower colonic and rectal movements.     

Intraesophageal acid perfusion sensitizes the esophagus to mechanical distension: a Barostat study

OBJECTIVE: The pathogenesis of noncardiac chest pain is unclear. Increased gastroesophageal reflux and decreased pain thresholds to intraesophageal balloon distension have been demonstrated in a proportion of such patients. We aimed to investigate whether acid exposure sensitizes esophageal mechanoreceptors in healthy volunteers. METHODS: After an overnight fast, an infinitely compliant balloon, 4.5 cm in length and mounted on a multilumen transnasal manometry catheter, was placed 8.5 cm above the lower esophageal sphincter in 12 healthy male volunteers aged 18-39 yr. After determination of the minimal distending pressure, the balloon was inflated up to 48 mm Hg by means of a computer-controlled barostat (G & J Electronics, Canada). Graded stepwise distensions were interspersed with random decreases in pressure to two-thirds of the previous value. At each pressure level, the subjects were asked to report on sensation and the presence of pain. Baseline distension was repeated to determine reproducibility of the pressure/volume relationship and also the perception and pain thresholds. After the baseline distension sequence, the esophagus was perfused for 20 min (at 7 ml/min) with either normal saline (control) or 0.1 N hydrochloric acid at 37 degrees C on a random basis. RESULTS: Basal sensory thresholds varied widely (first perception 5-36 mm Hg, pain 8 > or = 43 mm Hg). Two subjects did not experience pain up to the maximum distending pressure (42 and 43 mm Hg, respectively, after correction for the minimal distending pressure). Esophageal body compliance was similar on repeat distension. Sensory thresholds were reproducible with different distensions (perception r = 0.99, pain r = 0.95). Saline resulted in no significant changes in perception or pain thresholds. Acid perfusion reduced first perception (median before and after acid, 15 mm Hg and 8 mm Hg, respectively, p = 0.05) and pain threshold (median before and after acid, 32.5 mm Hg and 26.5 mm Hg, respectively, p = 0.05). When compared to changes after saline perfusion, acid perfusion reduced the perception threshold (median change, -3.8 mm Hg vs 0 mm Hg, p = 0.04) and tended to reduce the pain threshold (median change, -3.75 mm Hg vs +0.75 mm Hg, p = 0.09). CONCLUSIONS: Intraesophageal balloon distension using a barostat is a reproducible method of measuring esophageal body compliance and sensory thresholds. Acute exposure to acid seems to sensitize the esophagus to perception from intraluminal balloon distension.     

Sensitivity and distensibility of the rectum and sigmoid colon in patients with irritable bowel syndrome

BACKGROUND: Hyperalgesia to visceral stimuli is a biological marker of the irritable bowel syndrome (IBS). Abnormal pain processing is probably of most importance, but biomechanical abnormalities of the gut wall may also contribute to the findings. In the current study, we investigated the sensation of the gut to electrical stimuli as well as the distensibility of the rectum and sigmoid colon in IBS patients and a control group. METHODS: Nine patients with IBS and 11 controls entered the study. The pain threshold to electrical stimuli at the rectosigmoid junction was determined with bipolar electrodes integrated on the biopsy forceps for the endoscope. Subsequently, controlled distensions of the sigmoid colon and rectum were performed with a balloon integrated on a probe for impedance planimetry, providing the possibility to measure the cross-sectional area (CSA), wall tension and strain to different pressures together with the sensation ratings. RESULTS: The pain detection thresholds to electrical stimuli at the rectosigmoid junction were 12.5 (range 7-39) mA in controls and 7.5 (range 0.75-12) mA in IBS patients (P = 0.03). The calculated pressures at the pain detection threshold in the sigmoid colon were lower in the IBS patients (31.5 (range 5-58) versus 5 cm (range 5-25) water; P = 0.03), otherwise no differences were seen in sensation rating to the different distension pressures. The CSA was slightly higher in controls to the different pressures, whereas no differences between the groups were seen in strain and tension of the rectum and sigmoid colon. CONCLUSION: The visceral hypersensitivity in IBS seems to be related to alterations in the nervous system rather than biomechanical parameters such as the tension and strain of the gut wall. Treatment of pain in IBS should therefore be based on drugs with documented action on the nociceptive pathways in the central nervous system.     

Colonic manometry in children with chronic intestinal pseudo-obstruction.

Pressure changes were evaluated in the transverse, descending, and rectosigmoid colon of 30 children with chronic intestinal pseudo-obstruction. Twenty two had severe lifelong constipation and eight had symptoms suggesting a motility disorder exclusively of the upper gastrointestinal tract. Based on prior antroduodenal manometry, 24 children were diagnosed as having a neuropathic and six a myopathic form of intestinal pseudo-obstruction. On the day of study, endoscopy was used to place a manometry catheter into the transverse colon and intraluminal pressure was recorded for more than four hours. After a baseline recording, we gave a meal to assess the gastrocolonic response. Colonic contractions were noted in 24 children. The six children with no colonic contractions had a hollow visceral myopathy and constipation. In the children with colonic contractions, fasting motility did not differentiate children with and without constipation. After the meal, in all eight children without constipation there was (1) an increase in motility index (3.2 (SEM 0.3) mm Hg/min basal v 8.4 (SEM 1.1) mm Hg/min postprandial; p < 0.001), and (2) at least one high amplitude propagated contraction (HAPC). In the 16 constipated children with colonic contractions the motility index did not significantly increase after the meal (2.1 (SEM 0.3) mm Hg/min basal v 3.1 (SEM 0.4) mm Hg/min postprandial) and 12 of them had no HAPCs (p < 0.01 v group without constipation). In summary, in children with a clinical diagnosis of chronic intestinal pseudo-obstruction, constipation is associated with absence of HAPCs, and the gastrocolonic response or with total absence of colonic contractions. It is concluded that studies of colonic manometry are feasible in children and may document discrete abnormalities in those with intestinal pseudo-obstruction with colonic involvement.     

Sigmoidismus or Sigmoid-Rectosigmoid Junction Dyssynergia Syndrome A New Clinicopathologic Entity

We previously reported that the rectosigmoid junction (RSJ) reacts to sigmoid contraction by opening and to rectal contraction by closing [28]. The current communication presents 19 patients (age 43.3 - 6.2 years; 15 women, 4 men) complaining of chronic idiopathic constipation which proved to be due to sigmoid-rectosigmoid junction incoordination. Ten healthy volunteers matching the patients in age and gender, acted as controls. Intestinal transit test, defecography, and EMG of the external anal sphincter and levator ani muscle were performed. The pressures in the sigmoid colon, rectosigmoid junction, rectum and rectal neck (anal canal) in response to individual sigmoid or rectal distension in increments of 10 ml CO₂ were determined. In the patient group, the intestinal transit test showed the markers accumulating in the sigmoid colon. The basal pressures in the sigmoid colon, rectosigmoid junction, rectum and rectal neck were similar in the patient and control groups. In the healthy controls mean sigmoid distension with 93.6 -, 3.5 ml effected sigmoid contraction, rectosigmoid junction relaxation and balloon expulsion to the rectum while in the patients effected no response. The sigmoid colon pressure in the patients rose at a mean distending volume of 108.6 - 7.3 ml and was elevated up to a volume of 136.6 - 10.8 ml but the rectosigmoid junction pressure showed no change and the balloon was not dispelled. Rectal distension in controls produced rectosigmoid junction pressure rise, while in the patients showed no response. Sigmoidismus or failure of the rectosigmoid junction to dilate upon sigmoid distension was diagnosed. Sigmoidoplasty, performed in 14/19 patients, cured 11. Sigmoidismus is a new clinicopathologic entity that should be considered in the diagnosis of chronic idiopathic constipation. Open rectosigmoidoplasty effected cure in 78.5%; the procedure is suggested to be performed laparoscopically.     

The role of tension receptors in colonic mechanosensitivity in humans

BACKGROUND: Perception of colonic distension, which is enhanced in a subset of patients with irritable bowel syndrome, requires activation of mechanoreceptors. In animal studies, distension activates both in series ("tension") and in parallel ("elongation") mechanoreceptors. During active contractions against a fixed volume balloon, tension receptors are activated without elongation of receptor activation. AIM: To evaluate the role of tension receptors in the perception of mechanical stimuli from the colon in healthy subjects. METHODS: A 700 ml balloon connected to a barostat-manometer assembly was placed in the descending colon of 10 healthy subjects. After volume controlled distension (50 ml/2 minutes) to assess the first perception threshold, fixed volume subthreshold distension (122 (16) ml) was maintained for a 30 minute period before and after administration of neostigmine 0.5 mg intravenously. Mean intraballoon pressure, number, amplitude, and duration of contractions, and frequency of sensations were analysed. The period after neostigmine was divided into 10 second intervals and evaluated for the occurrence of contractions and onset of sensations. Fisher's exact test was applied to calculate the sensation-contraction association probability (SAP) as (1.0-p)x100%. RESULTS: Neostigmine increased intraballoon pressure (p<0.01), number of contractions (p<0.01), and number of sensations (p<0.01) per minute in all subjects. In seven of 10 subjects a significant association (SAP >95%) was found between sensations and contractions. In the remaining subjects, contractions were not associated with sensations and had lower amplitude (p<0.05) and duration (p<0.01) compared with contractions in the other seven subjects. CONCLUSION: In humans, tension receptors are involved in mediating colonic mechanosensitivity.     

Sensitivity and Distensibility of the Rectum and Sigmoid Colon in Patients with Irritable Bowel Syndrome

Background: Hyperalgesia to visceral stimuli is a biological marker of the irritable bowel syndrome (IBS). Abnormal pain processing is probably of most importance, but biomechanical abnormalities of the gut wall may also contribute to the findings. In the current study, we investigated the sensation of the gut to electrical stimuli as well as the distensibility of the rectum and sigmoid colon in IBS patients and a control group. Methods: Nine patients with IBS and 11 controls entered the study. The pain threshold to electrical stimuli at the rectosigmoid junction was determined with bipolar electrodes integrated on the biopsy forceps for the endoscope. Subsequently, controlled distensions of the sigmoid colon and rectum were performed with a balloon integrated on a probe for impedance planimetry, providing the possibility to measure the cross-sectional area (CSA), wall tension and strain to different pressures together with the sensation ratings. Results: The pain detection thresholds to electrical stimuli at the rectosigmoid junction were 12.5 (range 7-39) mA in controls and 7.5 (range 0.75-12) mA in IBS patients (P = 0.03). The calculated pressures at the pain detection threshold in the sigmoid colon were lower in the IBS patients (31.5 (range 5-58) versus 5 cm (range 5-25) water; P = 0.03), otherwise no differences were seen in sensation rating to the different distension pressures. The CSA was slightly higher in controls to the different pressures, whereas no differences between the groups were seen in strain and tension of the rectum and sigmoid colon. Conclusion: The visceral hypersensitivity in IBS seems to be related to alterations in the nervous system rather than biomechanical parameters such as the tension and strain of the gut wall. Treatment of pain in IBS should therefore be based on drugs with documented action on the nociceptive pathways in the central nervous system.     

提高对结肠冗长症的认识、诊断及外科治疗

结肠冗长症是一种先天性结肠畸形,是结肠在发育过程中因基因再复制而生长过长所致。主要表现为腹痛、腹胀和长期顽固性便秘。X线钡剂灌肠造影是诊断结肠冗长症的主要手段。如果升、横、降结肠或乙状结肠的任何一段长度超过标准长度的35%～40%,即可诊断为结肠冗长症。具有长期顽固性便秘者,非手术治疗无效者,可行外科手术治疗,并且多数学者主张行扩大范围的切除。     

Twenty four hour manometric recording of colonic motor activity in healthy man.

The motor activity of the transverse, descending, and sigmoid colon was recorded for 24 hours in 14 healthy volunteers with a colonoscope positioned catheter. During the study the patients ate two 1000 kcal mixed meals and one continental breakfast. Colonic motor activity was low before meals and minimal during sleep; the motility index increased significantly after meals and at morning awakening. Most of the motor activity was represented by low amplitude contractions present singly or in bursts, which showed no recognisable pattern. All but two subjects also showed isolated high amplitude (up to 200 mmHg) contractions that propagated peristaltically over long distances at approximately 1 cm/sec. Most of these contractions occurred after morning awakening, and some in the late postprandial period, with a mean of 4.4/subject/24 h. The peristaltic contractions were often felt as an urge to defecate or preceded defecation, and could represent the manometric equivalent of the mass movements.     

Differences in colonic tone and phasic response to a meal in the transverse and sigmoid human colon.

It is not yet clear whether the regional differences in the physical properties of the colon influence its motor responses. Tonic and phasic colonic motility and compliance of the transverse and sigmoid colon were therefore assessed using a combined barostat-manometry assembly in 22 healthy subjects. Measured colonic compliance was corrected by subtraction of the compliance of the closed barostat system. The mean (SEM) preprandial colonic volumes in the transverse and sigmoid colon were similar (150 (12) and 128 (13) ml, p = NS), corresponding to calculated mean (SEM) colonic diameters of 4.3 cm and 4.0 cm respectively. The mean increase in colonic tone postprandially was significantly greater in the transverse (24.1% (3.5)) than in the sigmoid colon (13.1% (3.0), p < 0.01). The mean increase in phasic contractility was significantly greater, however, in the sigmoid than in the transverse colon (1270 (210) and 425 (60) mm Hg/90 min respectively, p < 0.01). Compliance was greater in the transverse than sigmoid colon (7.6 (0.44) and 4.1 (0.15) ml/mm Hg, p < 0.001). The fasting volume of the colon was significantly correlated with the magnitude of the tonic response to the meal in the transverse and sigmoid colon (p < 0.001 for both). In conclusion, there are quantitatively different but qualitatively similar phasic and tonic responses to the meal in the two colonic regions. Differences in the viscoelastic and luminal dimensions may partly account for these differences in tonic responses.     

Postprandial colonic transit and motor activity in chronic constipation

The aim of this study was to correlate colonic motility and transit in patients with constipation and symptoms of the irritable bowel syndrome. Studies were performed in 16 patients with constipation and compared with the results in 12 healthy subjects. Intraluminal pressure was measured with perfused catheter ports in the transverse colon, splenic flexure, and descending and sigmoid colon. Movement of the luminal contents was measured by following the movement of Technetium-99m-DTPA that was instilled as a bolus in the splenic flexure. In both healthy subjects and patients with constipation there was no movement of the intraluminal tracer and no increase in intraluminal pressure during fasting. After eating a meal, healthy subjects and one group of the constipated patients had an increase in the radioactive marker in the transverse colon (p less than 0.03) and in the sigmoid colon (p less than 0.03). The movement of the intraluminal contents was associated with a positive pressure gradient between the descending colon and the transverse and sigmoid colon. There was no retrograde movement of the intraluminal contents and no postprandial increase in intraluminal pressure in the second group of patients with constipation. In healthy subjects, propagating contractions, which were associated with the rapid movement of intraluminal contents, began 60 min after eating. There were no propagating contractions in patients with constipation. These studies suggest that (a) the movement of intraluminal contents in healthy and constipated patients is determined by the postprandial pressure gradients within the colon, and (b) the propagating contraction is necessary for a normal bowel habit.     

Case report: colonic manometry reveals abnormal propulsive behaviour after anterior resection of the rectum

Anterior resection of the rectum is a frequent surgical procedure. However, abnormal bowel habits following this procedure are frequently reported. The functional evaluation of these patients is usually limited to the anorectal area. By means of colonic manometry, we have evaluated a patient with frequent urge for defecation and increased bowel frequency following anterior resection of the rectum with straight coloanal anastomosis and almost normal anorectal function. Analysis of the tracing revealed a reduction of contractile segmental activity and much more high-amplitude propagated contractions than which occur in healthy subjects. These high-amplitude propagated contractions, representing the manometric equivalent of mass movements, were always in association with urge for defecation and, sometimes, with loose stools. High-amplitude simultaneous contractions were also observed. We feel that the surgical resection of a potential physiological brake may be responsible for these observations.     

Coloanal motor coordination in association with high-amplitude colonic contractions after pharmacological stimulation

OBJECTIVE: The rectoanal inhibitory reflex facilitates defecation by relaxation of the internal anal sphincter during rectal distention by gas or stool. Defecation is sometimes preceded by high-amplitude propagated contractions (HAPCs). Our objective was to seek evidence for motor coordination between human colonic and anal sphincter functions. METHODS: As part of a study of alpha2 modulation of colonic and anal motor functions in 32 healthy volunteers, we studied the relationship between high HAPCs and anal sphincter pressure with colonic manometry, barostat, and a Dent sleeve in the anal canal. RESULTS: Twenty-two HAPCs were observed; in 19/22 HAPCs there was optimal positioning of the Dent sleeve to assess the anal sphincter. Eighteen of 19 HAPCs occurred postprandially; 14 HAPCs occurred after administration of yohimbine, three after clonidine, and one before any drug administration. Seven followed experimental balloon distention. Anal sphincter relaxation occurred (14 +/- 4 s) before the recorded onset of HAPC in the descending colon and 88 +/- 7 s before the arrival of the HAPC in the rectum. After or during the HAPCs, anal sphincter pressure decreased by 40 +/- 4% and increased by 56 +/- 8% in the postrelaxation phase. CONCLUSIONS: The close temporal association between anal sphincter relaxation and onset of HAPC in the descending colon suggests a coloanal reflex that may facilitate defecation during mass movements independently of the rectoanal inhibitory reflex.     

Colonic motility and transit in health and ulcerative colitis

Preprandial and postprandial colonic motility and transit (scintigraphy), with respect to the splenic flexure, were studied in 10 patients with ulcerative colitis and in 9 healthy subjects. The healthy subjects had a postprandial increase in intraluminal pressure that was significantly (P less than 0.03) greater in the descending colon than in other regions of the colon. In ulcerative colitis, the pressure was decreased in all regions compared with healthy subjects, with no significant pressure gradient among different regions. In normal subjects, transit was quiescent during fasting; eating stimulated both antegrade and retrograde transit. In ulcerative colitis, transit was variable before as well as after the meal. Both healthy subjects and patients with ulcerative colitis had more rapid emptying from the splenic flexure into the sigmoid than into the transverse colon. More frequent, low-amplitude, postprandial propagating contractions occurred in ulcerative colitis (P less than 0.05) than in healthy subjects. Propagating contractions were always antegrade and caused a rapid movement of the tracer into the sigmoid. In conclusion, ulcerative colitis is characterized by (a) decreased contractility, (b) increased low-amplitude propagating contractions, and (c) variable transit. These disturbances may accentuate the diarrhea in ulcerative colitis.     

Response of canine ileocolonic sphincter to intraluminal acetic acid and colonic distension

The aim was to determine the effect of intraluminal acetic acid and proximal colonic distension on canine ileocolonic sphincter pressure, ileal motility, and coloileal reflux. In six conscious dogs with an isolated ileocolonic loop, basal pressure of the ileocolonic sphincter was similar during ileal perfusion with 100 mM acetic acid at 1 ml/min (mean±sem=18±0.4 mm Hg) and with saline (18±0.5 mm Hg;P=0.81). Discrete clustered ileal contractions were more frequent with acetic acid, however, and when they propagated across the sphincter, sphincter pressure increased from 18±0.4 mm Hg to 36±1.3 mm Hg (P=0.002). Sphincter pressure was also greater during colonic perfusion with acetic acid (32±0.7 mm Hg) than during ileal perfusion with acetic acid or saline (P<0.017). Moreover, sphincter pressure gradually increased as the colon was distended with saline (slope=0.8 mm Hg/cm H₂O,P<0.017) or acetic acid (slope=0.5 mm Hg/cm H₂O,P<0.017), but the increase did not prevent coloileal reflux. In conclusion, ileal clustered contractions, colonic perfusion of acetic acid, and colonic distension all increased canine ileocolonic sphincter pressure.     

昆明地区结直肠肿瘤260例

目的:分析单中心收治的结直肠肿瘤患者的临床特点,为临床诊治提供参考.方法:回顾分析我院2010年经外科手术确诊的260例原发性大肠肿瘤患者临床资料,探讨确诊大肠肿瘤临床特点及其与吸烟、饮酒和既往病史等可能影响其发生发展的因素的关系.结果:大肠肿瘤患者的男女比例为1.24∶1,平均年龄61.73岁±11.56岁.好发部位依次为直肠、乙状结肠、升结肠、横结肠和降结肠,同时性多发癌8例.64.23%的直肠肿瘤距肛门≤8cm,男性直肠肿瘤距肛门的距离(8.22cm±3.35cm)明显大于女性(7.08cm±2.09cm,t=2.20,P=0.03).直肠和左半结肠以大便带血为主,右半结肠以腹痛腹胀为主,大便潜血阳性率为80.43%.DukesA期比例升至18.85%,分化程度和年龄负相关(r=-0.145,P=0.019).胆囊切除术后患者右半结肠肿瘤比例高(P>0.05),高血压病史患者器官转移比例低(P<0.05).结论:直肠指诊和大便隐血实验是重要的检查方法;大便带血和腹胀腹痛分别是左半结肠、直肠和右半结肠的主要症状;大肠肿瘤早期诊断率呈增高趋势;年龄、胆囊切除术和高血压病可能是影响大肠肿瘤发生发展的因素.