Vincristine alters myoelectric activity and transit of the small intestine in rats

We investigated the motility of the small intestine in unanesthetized rats receiving vincristine (0.075, 0.50, 0.75 mg/kg i.v.). Motility was determined by two methods: myoelectric activity was monitored with indwelling bipolar electrodes, and intestinal transit was measured by the movement of radiochromium (Na51CrO4). Only the animals injected with the two higher doses had two distinct patterns of altered intestinal myoelectric activity within 2 h of drug administration. The first alteration occurred 44 +/- 6 min after vincristine administration and consisted of a marked increase in action potential activity with disruption of the migrating myoelectric complex. The second alteration consisted of a reappearance of the activity front of the migrating myoelectric complex with a significantly shorter periodicity. A marked reduction in spike activity occurred 3 days after vincristine injection in 3 of 10 animals receiving vincristine. A biphasic response was noted in intestinal transit. Disrupted activity front formation was associated with a significant delay in small bowel transit. In contrast, frequent activity front formation in rats was associated with significantly hastened transit. In summary, vincristine administration induces alterations of myoelectric activity of the small intestine in fasted rats and is associated with changes in intestinal transit.     

Human interdigestive and postprandial gastrointestinal motor and gastrointestinal hormone patterns

Fasting gastrointestinal motor and hormone patterns were studied in 11 healthy volunteers. Cyclic motor activity was present in all subjects during fasting, but the duration and site of onset of each cycle were variable, even in the same subject. Fasting gastrin, GIP, and glucagon levels remained low and constant during the 8-hr study, while plasma motilin levels exhibited cyclic variation in 7 of the 11 subjects. Achlorhydria (induced with cimetidine in 5 of the 11 subjects) did not alter the pattern of fasting motor activity or plasma motilin. In the remaining six subjects, the effect of liquid nutrient meals was examined. Ingestion of a sodium chloride bolus failed to disrupt fasting cyclic activity, while all nutrient-containing solutions inhibited gastric phase-2 motor activity, the duration of inhibition being longest for the mixed and lipid meals. All nutrient meals released GIP, while only protein and mixed meals released gastrin, and the lipid meal released motilin. Our study confirms the rhythmicity of interdigestive motor cycles in man and demonstrates their lack of dependence on gastric acid secretion and some relationship to motilin cycles in certain individuals as determined by radioimmunoassay. Transition from fasting to fed pattern (after liquid meals) is characterized by the inhibition of phasic gastric pressure changes in the antrum and the development of irregular activity in the intestine, similar in pattern to fasting phase 2. Because the duration of interruption of the gastric interdigestive pattern by meals depends on their nutrient content, we conclude that dietary composition may be a major determinant of the fasting-fed motor balance in man.     

Electrical spike activity in the human small intestine

An intraluminal probe with 10 pairs of bipolar electrodes was used for continuous recording of myoelectric activity along the entire small intestine during 24 hr in 2 normal fasting human subjects. Two types of regular migrating activity were observed: (1) Bands of a great number of spike potentials appearing at hourly intervals migrating through the entire small intestine. This activity, corresponds to phase III of the interdigestive myoelectric complex described in animal experiments. (2) Bursts of a few spike potentials appearing with minute intervals migrating only through the jejunum. This activity has not previously been demonstrated in man nor in intact animals, but corresponds to the minute-rhythm described fromin vitro experiments.This study was supported by Danish Research Council and grants from Frk. P.A. Brandt's Legacy.     

Fractionated doses of ionizing radiation alter postprandial small intestinal motor activity

We investigated the effects of total abdominal fractionated irradiation on postprandial small intestinal motor activity in five dogs. Five strain-gauge transducers were attached to the seromuscular layer of the duodenum, jejunum, and ileum of each dog to record circular muscle contractions. Radiation (250 cGy) was administered three times a week on alternate days for three successive weeks (total dose, 2250 cGy). Postprandial 4-hr recordings were made once each week during radiation and at one and three weeks following completion of radiation. Duodenal mean amplitude and area under contractions did not change during or following the radiation schedule, but the mean frequency and duration of duodenal contractions decreased during the radiation schedule. Both parameters returned to baseline values postirradiation. Jejunal mean duration, amplitude, area, and frequency of contractions decreased during radiation; mean amplitude and area returned to baseline values postirradiation but not the duration and frequency of contractions. All parameters of ileal contractions decreased during radiation, and all but area and amplitudes remained depressed postirradiation. Significantly decreased strength and frequency of contractions, particularly in the jejunum and ileum occur during and following irradiation. These changes may potentially alter transit time.Supported in part by NIDDK grants DK43104 to Dr. M.F. Otterson and DK32346 to Dr. S.K. Sarna.     

Phytase activity in the human and rat small intestine.

Phytate is the major storage form of phosphorus in seeds and so is a common dietary constituent. Excessive ingestion of undegraded phytates can cause mineral deficiencies in humans. In addition, phytic acid is antineoplastic in animal models of both colon and breast carcinoma. There have been no previous studies quantifying phytase activity in the human small intestine although it is present in animals. Small intestinal phytase and alkaline phosphatase activity and distribution was measured in vitro in mucosal homogenates from two human small intestinal specimens obtained from transplant donors. Rat intestine was also studied for comparison. Phytase activity was found in human small intestine at low values (30 times less than that in rat tissue and 1000-fold lower than alkaline phosphatase in the same tissue). The activity was greatest in the duodenum and lowest in the ileum. In conclusion, the normal human small intestine has very limited ability to digest undegraded phytates. Although this may have adverse nutritional consequences with respect to metabolic cation imbalances, the presence of undigested phytate in the colon may protect against the development of colonic carcinoma.     

Migrating electrical spike activity in the fasting human small intestine

The purpose of the present investigation was to describe characteristics of migrating electrical phenomena in the human small intestine. A specially designed probe with several bipolar electrodes was placed in the upper small intestine of 5 normal, fasting volunteers for continuous registration of electrical spike potentials. A migrating myoelectric complex was observed resembling observations made previously in animal experiments. The active phase consisted of regular spike potentials propagating distally at a mean velocity of 12 cm/min, and a duration of about 5 min. In addition a, peristaltic rush was observed consisting of spike potentials with a high amplitude, propagating distally at a mean velocity of 2 cm/sec and a duration of about 5 sec.This study was supported by Danish Research Council and grants from Frk. P.A. Brandt's Legacy.     

Rectal distension inhibits postprandial small intestinal motor activity partially via the adrenergic pathway in dogs

Objective. Rectal distension is known to induce numerous upper gastrointestinal symptoms. The aim of this study was to investigate the effects and mechanisms of rectal distension on small intestinal myoelectrical and motor activities in 8 dogs using a pair of intestinal electrodes and an intestinal fistula. Material and methods. Experiment 1 entailed a 30-min baseline recording and a 30-min recording during rectal balloon distension at various volumes (60, 80, 100 and 120 ml) randomly. Experiment 2 comprised three sessions, each including a 30-min baseline recording, a 20-min recording after intravenous infusion of saline, phentolamine (3 mg/kg) or propranolol (3 mg/kg), respectively, and another 30-min recording during rectal balloon distending. Results. 1) Rectal distension resulted in reduced intestinal motility in a dose-dependent manner (r=0.68, p<0.001). 2) The reduction in intestinal motility was significantly diminished when infusions of phentolamine (2.7±1.0 versus 8.4±1.5, p<0.01) or propranolol (3.7±1.4 versus 8.4±1.5, p<0.05) were given, suggesting partial involvement of the alpha- and beta-adrenergic pathways. 3) Rectal distension did not affect the percentage of normal 17–22 cycles/min intestinal slow waves (97.5±2.5 versus 93.0±5.3, p>0.05), or their dominant frequency (17.2±1.2 counts per minute (cpm) versus 17.7±1.0 cpm, p>0.05), or dominant power (?4.8±2.5 versus ?8.2±2.9 dB, p>0.05). Conclusions. Rectal distension inhibits postprandial small intestinal motor activity in a distension volume-dependent manner in dogs, and this inhibitory effect is at least partially mediated via the alpha and beta adrenergic pathways and does not involve any alterations in intestinal slow waves.     

小肠黏膜改变与脑出血部位的关系

目的观察自发性脑出血患者小肠黏膜的变化,探讨小肠黏膜改变与脑出血部位的关系。方法分析31例自发性脑出血患者的出血部位与胶囊内镜下小肠黏膜改变的关系,并与10例健康成人对照。结果 31例患者中15例小肠黏膜有不同程度的充血、点状糜烂或浅溃疡形成;丘脑出血患者16例中,11例有不同程度点片状糜烂或浅溃疡形成,其中1例合并有活动性出血;15例非丘脑出血患者中4例有不同程度的糜烂,10例健康对照者未见明显糜烂、溃疡形成。丘脑出血小肠黏膜病变较非丘脑出血及健康对照者更明显(P<0.05),非丘脑出血及健康对照者对比差异无统计学意义(P>0.05)。结论小肠黏膜改变与自发性脑出血部位有着密切的相关性。本试验可为脑出血患者早期肠外营养治疗提供理论依据。     

Serotonin regulation of motor function of the small intestine

The review described serotonergic regulation of motor function of the small intestine. Motor neurons of the enteric nervous system and cells--pacemakers (cells of Cajal) play an important role in the regulation of motor activity of the small intestine. Activated serotonin receptors expressed by neuronal and effector cells initiate the phase II and III of the migrating motor complex (MMC), changes the duration of the cycle and frequency of MMC. Serotonin, acting on 5-HT(2B) -, 5-HT(3) - and 5-HT(4)-receptors expressed by the Cajal cell, regulate the frequency of slow waves and amplitude of electromotor activity of the small intestine.     

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.     

Acute lower gastrointestinal hemorrhage originating in the small intestine.

INTRODUCTION: Lower gastrointestinal hemorrhage (LGIH) is generally self-limiting, and the most frequent etiologies are located at colonic level. The objective here is to analyze the diagnostic and therapeutic handling of acute LGIH when its etiology was located in the small intestine. PATIENTS AND METHODS: Between 1975 and March 2002, 12 acute cases of LGIH originating in the small intestine were admitted to our service. All consulted the hospital with acute rectorrhage, requiring a transfusion of at least 3 units of concentrated red blood cells. The mean age was 54 +/- 21 years, 58% were women, and 83% had experienced previous episodes of LGIH. RESULTS: in eleven cases (92%) an urgent lower and upper endoscopy was performed without locating the source of bleeding. An arteriography was indicated in 7 patients (58%), which located the bleeding origin in 5 of them. In two cases a scintigraphy was performed, showing a Meckel's diverticulum in one patient and a normal image in another. All were operated on; in 8 cases (67%), surgery was urgent; in 9 cases, a tumor was found, and in three additional patients, a case of Meckel's diverticulum was found, with a resection being carried out for all lesions. Histology showed a leiomyoma in 7 cases, a Meckel's diverticulum in 3 cases, a leiomyoblastoma in 1, and an angioma in the remaining case. After a mean follow-up of 132 +/- 75 months, the leiomyoblastoma resulted in death, and there was a relapse in the case of angioma, which was successfully embolized with interventional radiology. CONCLUSIONS: Acute LGIH originating in the small intestine should be considered a possible etiology when digestive endoscopy does not locate the source of bleeding, with arteriography being a useful diagnostic technique for bleeding localization. Surgery is the definitive treatment--it confirms the etiology and rules out the presence of malignancy.     

Relationship between anal canal tone and rectal motor activity

The anal sphincters facilitate fecal continence by maintaining a pressure barrier; whether proximal contractile events influence this barrier is unknown. The aim of this study was to determine whether a relationship exists between anal canal pressures and rectal motor activity. A fully ambulatory system for prolonged pressure recording was developed. In 12 healthy subjects (seven males and five females; mean age, 35 years; range, 22–43 years), a flexible transducer catheter (outside diameter, 4.5 mm) was introduced endoscopically such that sensors were 2, 3, 8, 12, 18, and 24 cm from the anal orifice. Twenty-four-hour spontaneous motor activity was stored in a 2.5-megabyte portable recorder for later transfer to a Microvax II for computerized analysis and display. Mean anal canal pressure was calculated, and rectal motor complexes (RMCs) were characterized. Mean anal canal resting pressure was 75±12 mmHg. During sleep, anal pressures displayed cyclic decreases (mean periodicity, 1.6 hours; range, 1–4 hours), during which the mean ±SD pressure trough was 15±4 mmHg (range, 8–21 mmHg). RMCs were identified in all subjects: mean frequency, 16 per 24 hours (range, 12–22 per 24 hours); duration, 15.3 minutes (range, 8–35 minutes); contractile frequency, two to three per minute; mean peak amplitudes, 58±18 mmHg; and periodicity, 78±24 minutes (range, 35–265 minutes). Importantly, an RMC was invariably accompanied by a rise in mean anal canal pressure and contractile activity such that pressure in the anal canal was always greater than pressure in the rectum. Anal canal relaxations never occurred during an RMC. Motor activities of the rectum and of the anal canal may be related; the onset of rectal contractions was accompanied by increased resting pressure and contractile activity of the anal canal. This temporal relationship represents an important mechanism preserving fecal continence.Read at the meeting of The American Society of Colon and Rectal Surgeons, Boston, Massachusetts, May 12 to 17, 1991.     

Relationship between morphological findings and function of the small intestine in familial amyloidosis with polyneuropathy

Twenty-seven patients with familial amyloidosis with polyneuropathy were studied with regard to the morphology of the small intestine, and this was correlated to symptoms and malabsorption features. The mucosa was normal in all cases investigated by the dissecting microscope, the light microscope, and the scanning electron microscope. Amyloid was demonstrated in 83% of the cases by the presence of green birefringent material in the biopsy specimens stained with alkaline Congo red and examined in polarized light. Nineteen patients had steatorrhea, and 12 had pathological D-xylose test results. The degree of amyloid infiltration did not correlate with these data, nor did the symptomatic state correlate with the amount of amyloid in the biopsy specimens. The surface ultrastructure was normal when investigated by means of the scanning electron microscope in all patients except five in whom the glycocalyx was altered. As a group, however, those five did not differ in any respect from the rest of the patients. Rod-shaped microorganisms were shown to adhere to the surface in one patient. The results suggest that mechanisms other than bowel-wall deposition of amyloid cause the dysfunction of the gastrointestinal tract in familial amyloid polyneuropathy.     

Laparoscopic-assisted resection of gastrointestinal stromal tumor in small intestine

Gastrointestinal stromal tumors (GISTs) in the small intestine are relatively rare. We present a case of GIST arising from the small intestine, which could be resected under laparoscopic assistance. A 60-year-old male visited another hospital due to massive anal bleeding. Blood examination showed severe anemia. Although anemia improved after conservative treatment, the bleeding site was not identified and he was referred to our hospital for close examination. Abdominal CT showed a well-defined mass with homogeneous internal density in the left upper abdomen. On abdominal angiography, selective enhancement of the second jejunal artery revealed a tumor stain. Due to suspected GIST in the small intestine, laparoscopic-assisted resection of the jejunum was performed. Histopathological examination demonstrated low-grade malignant GIST. The laparoscopic procedure is considered to be useful as minimally invasive surgery for diagnosis and treatment of selected cases with GISTs in the small intestine.     

Ontogeny of fasting small intestinal motor activity in the human infant.

A clearly defined progression of fasting small intestinal motor development is seen in the human infant from disorganised low amplitude motor activity before 31 weeks gestation through an intermediate phase of increasing motor organisation and amplitude to the development of a normal cyclical pattern of motor activity with clearly defined phase I, II, and III activity between 37 weeks gestation and term. With increasing maturity smooth muscle contractility [gastric antral pressure (5-30 mmHg), average duodenal pressure (2-12 mmHg)], propagation and slow wave frequency (10.5-12.5 cpm) all increased in a significant fashion (p less than 0.01). The stage of development of fasting motor activity in the small intestine of the preterm infant can now be readily predicted from the gestational age of the infant.