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Biomedical subjects

W J Dodds

Publications and source records attributed to W J Dodds.

At least 127 records · Page 7Linked to original sources
PubMed1988

Effects of morphine on the human sphincter of Oddi.

The effects of morphine on intraluminal pressures recorded from the sphincter of Oddi (SO) at endoscopic retrograde cholangiopancreatography in 19 patients who were without evidence of biliary or pancreatic disease were studied. Morphine was given in four successive doses of 2.5, 2.5, 5, and 10 micrograms/kg iv at five minute intervals. Morphine in subanalgesic doses increased the frequency of SO phasic pressure waves to a maximum of 10-12/min, caused the phasic waves to occur simultaneously along the sphincter segment, increased phasic wave amplitude from 72 (26) (SE) to 136 (31) mmHg, and increased SO basal pressure from 10 (1) to 29 (9) mmHg (p less than 0.05). The effects of morphine on the SO are mediated by more than one opioid receptor type, as naloxone competitively antagonised the increase in phasic wave frequency induced by morphine, but did not affect the increase in SO basal pressure elicited by morphine. When given after naloxone, morphine decreased phasic wave amplitude, an inhibitory effect that is normally masked by morphine's dominant naloxone sensitive excitatory effect. Mu receptors do not appear to be involved in control of spontaneous SO motor function, as naloxone alone did not affect SO motor activity. The excitatory effects of morphine on the SO are not mediated by cholinergic nerves, as they were not blocked by atropine. Cholinergic nerves, however, may have a role in regulating spontaneous SO motor function because atropine alone depressed phasic wave activity and basal pressure. Although morphine does cause 'spasm' of the human SO, its effects are more complex than is commonly believed.

Adult↗
PubMed1988

Mechanisms of lower oesophageal sphincter incompetence in patients with symptomatic gastrooesophageal reflux.

Patterns of lower oesophageal sphincter (LOS) function associated with the onset of 644 reflux episodes were recorded and analysed in 67 patients referred for evaluation of gastro-oesophageal reflux (GOR). Patients were studied recumbent, for one hour before and four hours after a standard meal. Transient LOS relaxation was the most prevalent mechanism and overall accounted for 82% of reflux episodes. With increasing severity of oesophagitis, absent basal LOS pressure became a progressively more common mechanism, accounting for 23% of episodes in the patients with severe oesophagitis. Patients commonly exhibited more than one mechanism. The timing of most (69%) LOS relaxations associated with reflux was not compatible with triggering by swallowing. Prolonged transient LOS relaxations were associated with inhibition of oesophageal peristalsis suggesting that this response is produced by neural inhibition. This study suggests the primary importance of transient LOS relaxations as the cause of GOR across the spectrum of severity of reflux disease.

Esophagogastric Junction↗
PubMed1988

Relationship between transmural potential difference and smooth muscle slow waves and contractility in the rabbit small intestine in vitro.

The relationship between transmural potential difference (PD) and smooth muscle electrical and mechanical activity was investigated in the rabbit ileum in vitro. Transmural PD was monitored using agar salt bridge electrodes connected via calomel half cells to an electrometer. Force displacement transducers recorded predominantly longitudinal smooth muscle activity. Concurrently, predominantly circular muscle activity was recorded at three sites using intraluminal pressure probes. At the same sites, suction electrodes monitored electrical activity of the smooth muscle. In all experiments, fluctuations in transmural PD were temporally linked to smooth muscle mechanical and electrical activity. The frequency of PD oscillations, electrical slow waves, and cyclic pressure changes were identical within each segment. Adrenaline abolished smooth muscle electrical spiking, all mechanical activity, and transmural fluctuations in PD. However, the slow waves were not abolished, though their frequency was increased. Phentolamine but not propranolol reversed the effects of adrenaline, thus slow wave frequency is influenced by alpha-adrenergic stimulation in the rabbit ileum. In conclusion, oscillations in transmural PD are unrelated to the ionic processes associated with the slow wave. However, they are in some way linked to smooth muscle contractile activity, possibly via an intrinsic neural mechanism as observed in the guinea pig.

Animals↗
PubMed1988

Renal calculi: sensitivity for detection with US.

The sensitivity of sonography in the detection of renal calculi was tested in a three-phase study in 100 patients. In phase 1, ultrasonographic (US) scanning was performed after review of abdominal radiographs and renal tomograms in 30 patients who had undergone extracorporeal shock wave lithotripsy (ESWL). In this group the sensitivity of US for detecting stones was 98%. In phase 2, scanning was performed in 30 post-ESWL patients without prior review of radiographs or tomograms. The sensitivity of US for stone detection in this group was 95%. In phase 3, sonography was performed in a blinded fashion on a random mix of post-ESWL patients and patients who had undergone urography for reasons unrelated to nephrolithiasis. The sensitivity of US for stone detection in this group of 40 patients was 91%. The overall sensitivity in all three groups was 96%, which was superior to the performance of abdominal radiography and slightly inferior to the combination of abdominal radiography and renal tomography. The ability to detect kidney stones with US depended on stone size but was independent of stone location or patient size. The study findings suggest that US is an effective means for detecting kidney stones in patients with suspected nephrolithiasis.

Humans↗
PubMed1988

Canine gallbladder cyclic motor activity.

We investigated whether the gallbladder has cyclic motor activity similar to that of the stomach, lower esophageal sphincter, and sphincter of Oddi in the fasted state. We found that the canine gallbladder infundibulum exhibited a cyclic burst of short duration (69 +/- 3 s) contractions that were closely associated with phase III activity of the antrum. The cyclic motor activity was sometimes less prominent or absent in the body and the fundus of the gallbladder. The mean period of gallbladder cyclic motor activity was not significantly different from the mean period of phase III activity in the stomach and the duodenum. The cyclic bursts of gallbladder contractions lasted for 21 +/- 2 min. The gallbladder cyclic motor activity started at about the same time as the antral phase III activity, and both of these activities started approximately 12 min earlier than the duodenal phase III activity. In addition to the aforementioned cyclic bursts of contractions, the gallbladder sometimes exhibited long duration (6.4 +/- 0.6 min) contractions that occurred irregularly and unpredictably during the duodenal migrating motor complex cycle. We conclude that during fasting the canine gallbladder has a cyclic motor activity that is temporally related to phase III activity of the stomach and the duodenum. The role of short duration phasic contractions during cyclic motor activity may be to periodically stir gallbladder contents, whereas the long duration contractions may partially empty the gallbladder in the fasted state.

Animals↗
PubMed1988

Control mechanisms of sphincter of Oddi contraction rate in the opossum.

Our aim in this study is to determine whether extrinsic autonomic nerves regulated spike-burst rate in the opossum sphincter of Oddi (SO) during fasting or after feeding. We implanted electrodes on the distal SO, proximal SO, gastric antrum, duodenum, and jejunum of 20 animals. A cut transection and reanastomosis was done at different levels of the SO to interrupt putative extrinsic or intrinsic nerves, or the SO was painted with phenol to impair extrinsic nerves. Like controls, animals with a cut and reanastomosis at the proximal SO or at the SO-duodenal junction showed a normal fasting pattern of cyclic changes in SO spike-burst rate. In contrast, animals treated by a distal SO cut or phenol treatment at the distal SO lost the normal cyclic pattern of SO spike bursts and had a constant rate of approximately 4/min. A cut through the middle SO uncoupled the spike bursts in the proximal and distal SO. After feeding, all animals developed an SO spike-burst rate of 5-6/min that lasted for several hours. We conclude that the normal fasting pattern of SO spike bursts is regulated by extrinsic nerves that ascend cephalad along the sphincter segment, whereas the sustained increase in SO spike-burst rate after feeding is at least in part hormonal.

Action Potentials↗
PubMed1988

Influence of bolus volume on swallow-induced hyoid movement in normal subjects.

Swallowing normally elicits a superior-anterior excursion of the hyoid that contributes to elevation of the larynx and opening of the upper esophageal sphincter. The magnitude of hyoid movements, however, has not been quantitated with respect to the volume of the swallowed bolus. In this study, we determined the magnitude of superior and anterior movements of the hyoid associated with swallows of barium of different volumes. Lateral videoradiographic images of 2- to 20-ml boluses of barium were obtained in 15 subjects who had no pharyngoesophageal symptoms and had normal pharyngoesophageal motor function. Analysis indicated that a significant direct correlation existed between the volume of the swallowed bolus and the magnitude of the superior and anterior movements of the hyoid. For example, the mean values for these respective movements were 13.0 +/- 5 mm and 13.5 +/- 6 mm for a 2-ml bolus, compared with 14.8 +/- 5 mm and 16.7 +/- 5 mm for a 10-ml bolus. The findings indicate that values of deglutitive movement of the hyoid need to be indexed to the volume of the swallowed bolus. The results imply that the neural program in the brainstem that generates the oral and pharyngeal phases of swallowing is not completely stereotyped, but rather is modulated by volume-dependent sensory feedback.

Adult↗
PubMed1988

The pathogenesis of gastroesophageal reflux disease.

Reflux disease is a complex process in which different factors may contribute to the final common pathway of esophageal mucosal injury. Individual patients are heterogeneous with respect to the main determinants that contribute to the development of their symptomatic condition. Gastroesophageal reflux occurs by means of several different mechanisms that vary among patients. In many patients, resting LES tone is normal and reflux occurs via transient LES relaxations. In others with a hypotensive LES, acid reflux occurs mainly as stress of free reflux. Only this latter group is likely to exhibit barium reflux during fluoroscopy. Total esophageal exposure to acid material depends on a number of factors, including the rate of reflux, volume and potency of the refluxate, and efficacy of esophageal acid clearance. Abnormal esophageal exposure to acid refluxate depends on increased gastroesophageal reflux, delayed esophageal clearance, or both. Impaired esophageal acid clearance is generally caused by abnormal esophageal motor function that generally can be detected on barium-swallow examination.

Esophagogastric Junction↗
PubMed1988

Roscoe Miller award. Fatty-meal sonography for evaluating patients with suspected partial common duct obstruction.

We evaluated the efficacy of fatty-meal sonography for identifying patients with partial common duct obstruction. The test consisted of initial control measurements of common duct diameter followed by repeated measurements every 15 min for 60 min after a fatty meal consisting of Lipomul (1.5 ml/lb). The rationale proposed for the fatty-meal test is that in the presence of partial common duct obstruction, fat-induced increases in bile flow related to increased circulating levels of cholecystokinin are associated with an increase in the diameter of the common duct. Initial analysis of our data indicated that a change in diameter of +/- 1 mm was within the range of measurement error or possibly physiologic variation. In 44 control subjects (24 without a gallbladder), the common duct diameter either remained unchanged, showed an insignificant change of +/- 1 mm, or decreased (greater than or equal to 2 mm). The common duct diameter never showed an increase of more than 1 mm. The results of fatty-meal sonography in 47 patients with suspected partial common duct obstruction were negative in all 28 true-negative cases (specificity, 100%) and were positive (common duct increased by greater than or equal to 2 mm) in 14 of 19 true-positive cases (sensitivity, 74%). Thus, in this study a positive test finding always indicated partial common duct obstruction. Of the true-positive cases, fatty-meal sonography correctly identified seven of eight patients with cryptic obstructive sphincter-of-Oddi dysfunction (stenosis or dyskinesia) and five of nine patients with commun duct stones. We conclude that fatty-meal sonography is a useful noninvasive screening test for evaluating patients with suspected partial common duct obstruction.

Adolescent↗
PubMed1987

A bleeding disorder (von Willebrand's disease) in a Himalayan cat.

A bleeding disorder (von Willebrand's disease) was diagnosed in a 9-year-old male Himalayan cat examined because of persistent oral bleeding after routine dental extraction. Bleeding subsided after empirical treatment, which included prednisolone, vitamin K1, and transfusion of fresh blood, but recurred spontaneously after 8 months of apparent good health. Pertinent results of routine laboratory testing included an inconstant prolongation of the activated partial thromboplastin time and recurring iron-deficiency anemia. Assays of specific coagulation factors revealed low factor VIII coagulant activity and undetectable factor VIII-related antigen, a pattern considered to be diagnostic of von Willebrand's disease. This condition, not previously reported in a cat, should be included in the differential diagnosis when cats are examined because of abnormal bleeding.

Anemia, Hypochromic↗
PubMed1987

Effect of cisapride, a new prokinetic agent, on esophageal motor function.

In this study, we assessed by a double-blinded, cross-over design the effect of intravenous and oral cisapride on esophageal motor activity during the late fed state in normal subjects. For the intravenous study, subjects were given placebo or 10 mg cisapride randomly, while in the oral study, they randomly received placebo or cisapride at 5, 10, or 20 mg. Cisapride given intravenously or orally caused a significant increase in resting LES pressure. The increase in LES pressure after oral administration was significant only after the 20 mg dose. Esophageal-body peristaltic amplitude, determined for all smooth-muscle sites, showed a modest but significant increase of approximately 10 mm Hg after intravenous cisapride, whereas no significant increase occurred after oral cisapride. Propagation time of peristalsis was unaffected by intravenous or oral cisapride. Side effects of treatment were minimal and at no time necessitated cessation of the study. We conclude that in healthy subjects during the late fed period, (1) cisapride at 10 mg intravenously or 20 mg orally increased resting LES pressure and (2) at 10 mg intravenously, but at no oral dose, cisapride increased peristaltic amplitude without affecting propagation time. The potentiating effect of cisapride on LES pressure suggests that cisapride could have an ancillary role in the therapy of gastroesophageal reflux disease.

Adult↗
PubMed1987

Chronic recurrent pancreatitis secondary to a submucosal ampullary tumor in a patient with neurofibromatosis.

We report a 45-year-old nonalcoholic patient with Von Recklinghausen's disease and chronic recurrent pancreatitis. On endoscopy, a benign-appearing submucosal tumor surrounded the papilla of Vater. Cannulation of the pancreatic duct showed a dilated ductal system with subsequent delayed drainage. Endoscopic manometry revealed elevated sphincter of Oddi pressures. Endoscopic sphincterotomy resulted in immediate normal drainage of the pancreatic duct and in subsequent clinical improvement.

Ampulla of Vater↗
PubMed1987

A method for continuous monitoring of upper esophageal sphincter pressure.

We tested a manometric assembly employing a sleeve sensor that is able to monitor anterior or posterior pressure in the human upper esophageal sphincter (UES) for prolonged intervals. When compared to rapid pull-through measurement of UES pressure obtained with conventional manometric assemblies, the sleeve sensor measured significantly lower UES pressures with less variability between subjects, thereby suggesting that the rapid pull-through maneuver stimulates the UES to contract. Concurrent recordings of UES pressure with a sleeve sensor and a side-hole sensor during a slow station pull-through yielded almost equal pressure values at the peak of the high-pressure zone (station zero), but the side-hole site recorded significantly lower pressures than the sleeve at stations 0.5 cm or more from the peak of the high-pressure zone. During 10 min of recording at station zero, the sleeve sensor recorded greater pressures than the side-hole sensor. This finding demonstrated the suceptibility of the side-hole sensor to axial movement relative to peak UES pressure. When stationary, both the sleeve sensor and the side-hole sensor recorded significantly lower UES pressure after 1-2 min of recording, again suggesting that movement of the recording assembly stimulates the UES to contract. Sleeve recordings of swallow-induced UES relaxations showed that UES relaxations induced by water swallows were slightly longer than those induced by dry swallows. Augmentations of UES pressure induced by balloon distension of the esophageal body were also recorded. We conclude that the sleeve sensor is a suitable method for investigating the normal physiology and pathophysiology of the UES in human subjects.

Adult↗
PubMed1987

Subtypes of muscarinic receptors in vagal inhibitory pathway to the lower esophageal sphincter of the opossum.

We assessed the characteristics of muscarinic neural transmission in the vagal inhibitory pathway to the lower esophageal sphincter (LES) of anesthetized opossums. LES relaxation was induced by electrical stimulation of the cervical vagus. Measurements were made of LES relaxation before and after intravenous administration of nicotinic (hexamethonium), serotonergic (5-Meo-DMT), nonselective muscarinic (atropine), and selective muscarinic (pirenzepine-M1 and 4-DAMP-M2) antagonists. The latency of LES relaxation was increased substantially by pirenzepine and atropine, increased slightly by hexamethonium, but was not affected by 4-DAMP or 5-Meo-DMT. Given as concurrent intravenous infusions, hexamethonium, 5-Meo-DMT and 4-DAMP added to pirenzepine or atropine did not significantly increase LES relaxation latency above that caused by pirenzepine or atropine alone. None of the antagonists alone had a significant effect on percent LES relaxation. The combination of pirenzepine or 4-DAMP with hexamethonium and 5-Meo-DMT did not affect percent LES relaxation. The combination of atropine with hexamethonium and 5-Meo-DMT reduced LES relaxation to 18%. The combination of pirenzepine and 4-DAMP with hexamethonium and 5-Meo-DMT, however, had no effect on percent LES relaxation. We conclude that muscarinic participation in vagally induced LES relaxation exhibits two functional receptor subtypes: (1) M1 receptors that determine LES relaxation latency and are antagonized by pirenzepine or atropine, and (2) non-M1, non-M2 receptors (Mx receptors) that contribute to the magnitude of LES relaxation and are antagonized by atropine, but not by pirenzepine or 4-DAMP.

Animals↗
PubMed1987

Comparison of pseudoachalasia and achalasia.

Malignancies involving the gastric cardia or distal esophagus can result in a clinical syndrome termed pseudoachalasisa that mimics idiopathic achalasia. If not promptly recognized, pseudoachalasia can result in inappropriate pneumatic dilatation of the lower esophageal sphincter segment and delay appropriate treatment of the underlying malignancy. During the past 14 years, six patients with pseudoachalasia and 161 patients with primary idiopathic achalasia were encountered. Pseudoachalasia occurred mainly in the elderly and represented about 9 percent of these patients over 60 years of age with suspected achalasia. Five of the six pseudoachalasia cases were secondary to adenocarcinoma that originated in the gastric fundus, and one was caused by a squamous cell carcinoma of the distal esophagus. Conventional esophageal manometry did not discriminate achalasia from pseudoachalasia. On the other hand, esophagogastroscopy with biopsy resulted in a diagnosis of pseudoachalasia in five of these cases and in 24 of 32 cases reported previously. Ominous endoscopic findings are mucosal ulceration or nodularity, reduced compliance of the esophagogastric junction, or an inability to pass the endoscope into the stomach. Radiographic evaluation, particularly in conjunction with amyl nitrite inhalation, was also useful in discriminating pseudoachalasia from primary achalasia. It is concluded that pseudoachalasia generally mimics idiopathic achalasia imperfectly and can usually be diagnosed prior to surgery by fastidious endoscopic and radiographic examination.

Adult↗