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Biomedical subjects

W J Snape

Publications and source records attributed to W J Snape.

120 records · Page 7Linked to original sources
PubMed1977

Influence of vagal cooling on esophageal function.

Experiments were performed on adult opossums to determine the effect of decreased vagal activity on the esophageal peristalsis and lower esophageal sphincter (LES) relaxation associated with pharyngeal stimulation (PS) and esophageal balloon distension (ED). The cervical vagi were exposed and cooled (individually and bilaterally) to 3 degrees C using Dry Ice and alcohol-chilled saline. Unilateral vagal cooling had no effect on the esophageal peristalsis or LES relaxation associated with PS or ED. Similarly, bilateral vagal cooling did not alter the peristalsis and sphincter relaxation induced by ED. Bilateral vagal cooling, on the other hand, significantly decreased the incidence of peristalsis and the sphincter relaxation associated with PS. Studies were also performed to examine the effect of unilateral and bilateral vagotomy of esophageal function. Neither right nor left cervical vagotomy affected esophageal peristalsis or LES relaxation, regardless of the model of stimulation. Bilateral vagotomy, however, diminished the esophageal response to PS but was without effect on the peristalsis and LES relaxation produced in response to ED. From the studies we condlude: 1) the vagus nerve is of primary importance in regulating the esophageal response to PS, and 2) local neuromuscular factors within the esophageal wall appear sufficient to initiate and maintain an esophageal response to distension.

Animals↗
PubMed1977

Evidence that abnormal myoelectrical activity produces colonic motor dysfunction in the irritable bowel syndrome.

Although the irritable bowel syndrome is characterized as an abnormality in colonic motor activity occurring in response to certain stimuli, the etiology of this disorder is unclear. The purpose of this study is to determine the relationship of altered slow wave activity and the abnormal motility of the distal colon seen in patients with the irritable bowel syndrome. Myoelectrical activity was recorded using a bipolar electrode clipped to the distal colonic mucosa and motor activity was measured by perfused catheters. Colonic slow waves and contractions were present at two frequencies, 6 and 3 cycles per min. The slow wave frequency seemed to determine the frequency of colonic motor activity. Patients with the irritable bowel syndrome had increased 3-cycle per min slow wave activity in the basal state (P less than 0.001). However, no difference in basal 3-cycle per min motor activity was present between the two groups (P greater than 0.05). When colonic motor activity was increased with cholecystokinin or pentagastrin, patients with irritable bowel syndrome showed a marked increase in 3-cycle per min contractile activity, occurring simultaneously with 3-cycle per min slow wave activity. These studies suggest that increased colonic 3-cycle per min slow wave activity in patients with the irritable bowel syndrome may be the basic abnormality that leads to colonic motor dysfunction in response to various physiological stimuli.

Adult↗
PubMed1976

Marked alkaline phosphatase elevation with partial common bile duct obstruction due to calcific pancreatitis.

This study characterizes a syndrome of partial common bile duct obstruction and marked elevation in serum alkaline phosphatase in 6 male alcoholic patients with calcific pancreatitis. In each patient, a marked elevation in serum alkaline phosphatase was associated with minimal, if any, elevation in serum bilirubin. In all cases, the alkaline phosphatase was hepatic in origin, and intravenous or operative cholangiography showed a dilated common bile duct. Liver biopsy showed canalicular bile stasis in 4 patients and bile duct proliferation in 2 patients. This study demonstrates that calcific pancreatitis may cause partial bile duct obstruction which differentially increases serum alkaline phosphatase without altering bilirubin or bromsulphthalein excretion.

Adult↗
PubMed1976

Colonic myoelectric activity in the irritable bowel syndrome.

Although the irritable bowel syndrome has been characterized as an abnormality in colonic motor activity occurring in response to certain stimuli, the etiology of this abnormality is unclear. The purpose of this study was to compare colonic myoelectric and motor activity in normal subjects and in patients with the irritable bowel syndrome. Myoelectric activity was recorded using a bipolar electrode clipped to the mucosa of the rectal and rectosigmoid areas. Basic electrical rhythm (BER), spike potential activity, and intraluminal pressure were recorded in both groups. Two types of BER were observed. The major component of the BER had a frequency of approximately 6 cycles per min, whereas the minor component had a frequency of approximately 3 cycles per min. Although both types of BER were recorded in the two groups, thitable bowel syndrome. The 3 cycles per min activity was present as 44.1 +/- 1.3% of the total BER in the irritable bowel syndrome, as compared with 10.0 +/- 1.6% in the normal group (P less than 0.001). Basal spike potential and motor activity were similiar in both groups. Because it had been demonstrated previously that colonic responsiveness to certain stimuli was increased during the slower frequency BER, it is suggested that the abnormalities in colonic motor response reported in the irritable bowel syndrome may be related to this difference in colonic BER.

Adult↗
PubMed1976

Relationship of cervical and abdominal vagal activity to lower esophageal sphincter function.

The purpose of this study was to compare the effects of electrical stimulation of the abdominal and cervical portions of the vagus on lower esophageal sphincter (LES) pressure in the anesthetized opossum. Unilateral or bilateral abdominal vagotomy gave no significant change in basal LES pressure or in the sphincteric response to swallowing. Electrical stimulation of the peripheral end of the sectioned cervical vagus gave a frequency-related decrease in LES pressure with a maximum reduction of 93.5 +/- 2.5% at 10 HZ, 10 V. Stimulation of the central end of the cervical vagus increased LES pressure, with a maximum response of 34.0 +/- 1.9 mm Hg. Neither peripheral nor central stimulation of the sectioned abdominal vagus had significant effect on LES pressure (P greater than 0.05). Additionally, LES relaxation in response to swallowing or cervical vagal stimulation was intact after bilateral abdominal vagotomy. These studies suggest that whereas the cervical portion of the vagus mediates inhibitory and excitatory changes in LES pressure, the abdominal vagus has no demonstrable role in the control of LES function.

Abdomen↗
PubMed1975

Action of metiamide on the lower esophageal sphincter.

The action of metiamide, an H2 antagonist, was tested for its effect upon lower esophageal sphincter (LES) function in the anesthetized opossum. Intravenous infusions of metiamide gave a dose-related increase in LES pressure. A maximum increase in pressure of 17 mm Hg was attained at 2.0 mg per kg-hr of metiamide. This dose of metiamide abolished acid secretion in response to gastrin I, but augmented the maximal LES response to this hormone. Studies in vitro showed that metiamide augmented the maximal LES muscle responses to gastrin I or histamine but had no effect on other agonist responses. Metiamide alone did not alter LES muscle tension. An inhibitory response to gastrin I or histamine could be demonstrated in the presence of atropine or diphenhydramine, respectively, on muscle which had first been depolarized with KCl. These inhibitory responses were antagonized by metiamide. These studies indicate that metiamide: (a) increases LES pressure; (b) selectively augments LES muscle excitatory responses to gastrin I or histamine; and (c) selectively antagonizes inhibitory muscle responses to histamine or gastrin I.

Animals↗
PubMedDate not supplied

The effect of methylcellulose on symptoms of constipation.

The efficacy of methylcellulose was evaluated in 538 patients with a history of constipation. The patients were seen both by primary care physicians and by consultants. Patients were selected on the basis of passage of fewer than three stools per week. Frequency, consistency, and ease of passage of the stools were measured before and after one to three tablespoonsful per day of methylcellulose. The frequency of bowel movements as well as the consistency and ease of passage of the stools returned to normal with methylcellulose treatment; 61% of the patients were judged to have less constipation. The response to methylcellulose was not altered by the sex or age of the patients nor by the presence of colonic diverticular disease. This study suggests that methylcellulose is beneficial for the treatment of chronic and acute constipation.

Adolescent↗
PubMedDate not supplied

Disorders of colonic motility in patients with diabetes mellitus.

Motility disturbances of the colon can give significant symptoms in patients with diabetes mellitus. Constipation is a common complaint in these patients. Diarrhea associated with a generalized autonomic neuropathy can be very troublesome. There is a disturbance in the gastrocolonic response to eating in patients with diabetes mellitus who have constipation. These patients have no postprandial increase in colonic motility. However, their colonic smooth muscle contracts normally to the exogenous administration of neostigmine or metoclopramide. Stool softeners used in combination with the smooth muscle stimulants (neostigmine or metoclopramide) are helpful in treating constipation in patients with diabetes mellitus. Diarrhea can be treated with loperamide or diphenoxylate. Biofeedback may be useful in treating incontinence associated with diarrhea in these patients.

Colon↗
PubMedDate not supplied

Current concepts in the management of the irritable bowel syndrome.

In the irritable bowel syndrome gastrointestinal tract motility is disturbed from the esophagus to the colon, causing pain and altered function. When colonic motility is abnormal, the patient can experience either constipation or diarrhea in addition to abdominal pain and bloating. In constipated patients the postprandial colonic motility can increase normally after eating or the colon can remain motionless. Generally propagating contractions are absent in patients with constipation predominant irritable bowel syndrome. Propagating contractions are increased in frequency in patients with diarrhea, although the phasic contractions are decreased. Questionnaires discriminate between patients with structural disease such as ulcerative colitis and patients with functional disease, however they cannot differentiate between the different subgroups of patients with constipation predominant irritable bowel syndrome. Treatment strategies are beginning to focus on the underlying pathophysiologic abnormality.

Cisapride↗