Failure of transient lower oesophageal sphincter relaxation in response to gastric distension in patients with achalasia: evidence for neural mediation of transient lower oesophageal sphincter relaxations

Transient lower oesophageal sphincter relaxation (LOSR) is the major mechanism underlying gastro-oesophageal reflux. The mediation and control of LOSRs are incompletely understood but evidence suggests a neural inhibitory mechanism. In this study we have evaluated the effect of gastric distension on LOS function in 16 patients with untreated idiopathic achalasia and compared it with that in 10 healthy controls. With the subjects sitting, the stomach was distended with a liquid mixture that generated 750 ml CO2. Oesophageal pH and motility were monitored for 10 minutes before and after distension. In normal controls, gastric distension induced a four-fold increase in the rate of LOSRs and gas reflux episodes (as evidenced by oesophageal common cavities), whereas this response was absent in the achalasia patients. Basal LOS pressure did not change in either group. These findings are consistent with the notion that transient LOSRs induced by gastric distension are neurally mediated, probably by the same inhibitory nerves that govern swallow mediated LOS relaxation.

Upper esophageal sphincter tone and reactivity to stress in patients with a history of globus sensation

Anxiety and abnormal upper esophageal sphincter function have been ascribed ill-defined roles in the etiology of globus sensation. In this study, we examined the psychological profile and effect of acute mental stress (dichotic listening task) on UES tone in seven patients reporting to the clinic with globus sensation and 13 healthy controls. Alterations in heart rate, blood pressure, frontalis EMG, and skin conductance confirmed the effectiveness of the stress test in patients and controls. During resting conditions, UES pressure (mean +/- SE) in patients (40.4 +/- 4.6 mm Hg) did not differ significantly from controls (46.5 +/- 4.7 mm Hg). In response to stress, UES pressure rose by 31% in patients (P = 0.04) and by 25% in controls (P = 0.002). The stress-induced rise in UES pressure in patients (9.5 +/- 3.8 mm Hg) was not significantly different to that observed in controls (11.8 +/- 3.0 mm Hg). Psychological profiles of globus patients presenting to the clinic revealed them to be more introverted, anxious, neurotic, and depressed than normal controls. We conclude that in patients with a history of globus sensation, resting UES pressure and its response to stress is normal. Although individuals presenting to the clinic with globus sensation showed increased levels of psychoneurosis, acute, predictable stress is not a factor in the genesis of globus sensation. UES hyperresponsiveness to other stimuli or subjective intolerance to changes in UES pressure could account for symptoms of globus sensation.

Inhibitory function of VIP-PHI and galanin in canine pylorus

Contractions of canine pylorus and adjacent muscles were recorded with antral and duodenal strain gauges and a Dent sleeve manometric assembly with additional side holes in the pylorus. In vivo, vasoactive intestinal polypeptide (VIP) and peptide histamine isoleucine (PHI) given through the gastroepiploic artery inhibited both spontaneous and acetylcholine-induced pyloric contractions, before and after neural blockade with tetrodotoxin. Galanin inhibited only nerve-stimulated contractions. VIP greater than PHI much greater than galanin inhibited pyloric motor activity initiated by field stimulation of duodenal intramural nerves or intraduodenal infusion of 0.1 N HCl. In vitro, forskolin or field stimulation of nerves inhibited contractions of the pyloric muscle induced by various agonists but VIP-PHI failed to inhibit these contractions on two-thirds of the strips. The in vivo results suggest that VIP (or PHI) may be an inhibitory mediator in the pylorus acting directly on smooth muscle. Galanin may inhibit neural excitatory pathways in the pylorus. However, the structures on which VIP and PHI act in vivo may have become nonfunctional in vitro and other mediators account for the neural inhibition observed in isolated strips.

Pharmacokinetics and metabolism of SK&F 86002 in male and female Sprague-Dawley rats

Several pharmacokinetic parameters for SK&F 86002 [6-(4'-fluorophenyl)-5-(4'-pyridyl)-2,3-dihydroimidazo(2,1-b)-thia zole] and its metabolites (sulfoxide, sulfone) were measured in male and female Sprague-Dawley rats after iv (5 mg/kg) and a wide range (10-80 mg/kg) of oral doses of SK&F 86002. In both sexes. SK&F 86002 is metabolized to an active metabolite, sulfone, which has an extended half-life (approximately 13 hr) and, therefore, has the potential to accumulate upon repeated dosing. In addition, striking differences between sexes were noted in several of the pharmacokinetic parameters measured. The AUCs areas under the plasma concentration time curves, for SK&F 86002 in female rats obtained at the higher doses of SK&F 86002 were substantially greater than expected, when compared with lower doses in female rats or with equivalent doses in male rats. Furthermore, at all doses of SK&F 86002, AUCs for sulfoxide were substantially larger in female than in male rats. Consequently, the systemic exposure to SK&F 86002 and metabolites is substantially greater in female rats than in male rats. Therefore, extrapolation of the pharmacologic and toxicologic sequelae of SK&F 86002, observed at larger doses in female rats, to lower doses should be approached cautiously. Furthermore, the extended half-life of the pharmacologically active sulfone metabolite of SK&F 86002 suggests that this metabolite could accumulate on repeated daily dosing of SK&F 86002 and could, therefore, account for much of the chronic pharmacologic and toxicologic activity of SK&F 86002.

Evaluation of omeprazole in reflux oesophagitis

In patients with reflux disease, pH monitoring has shown that omeprazole virtually eliminates oesophageal exposure to a pH of less than 4. Motility studies concurrent with pH monitoring have indicated that reflux continues on omeprazole, its effect on acid exposure being entirely dependent on elevation of gastric pH. Omeprazole and placebo have been compared in 64 patients with erosive or ulcerative oesophagitis; the 4-week healing rates were 81% with omeprazole, 20 mg or 40 mg daily, and 6% with placebo. The efficacies of omeprazole at doses of 20 mg and 40 mg daily, were then compared in 164 patients. At 4 weeks, oesophagitis was healed in 70% and 82% of patients for the 20 mg and 40 mg doses respectively (p = 0.05). Eight-week healing rates (79% for 20 mg and 85% for 40 mg) did not differ significantly. Symptom response was excellent for both doses. Relapse of oesophagitis was determined over 6 months for patients healed with omeprazole. Relapse was shown to occur in 88 of 107 patients by 6 months. Omeprazole is a highly effective treatment for erosive/ulcerative peptic oesophagitis, 40 mg daily being marginally superior to 20 mg. Relapse is almost inevitable within 6 months of cessation of therapy.

Influence of posture on transient lower oesophageal sphincter relaxation and gastro-oesophageal reflux in the dog

The hypothesis that suppression of transient lower oesophageal sphincter relaxation (TLOSR) in recumbent postures in the dog is dependent upon the sensing of a gastric pool of liquid in proximity to the lower oesophageal sphincter was examined. Constant gastric insufflation with air (80 ml/min) was used to evoke TLOSR in unsedated, fasting animals. Oesophageal motility was monitored with a perfused manometric sleeve catheter assembly. Gastrooesophageal flow was recognized manometrically and by oesophageal pH recording. TLOSR occurred significantly less frequently in three recumbent positions (right lateral, left lateral and supine) than when the dog stood on four legs, but was more likely to be associated with acid reflux when they occurred in recumbent positions. Aspiration of the gastric pool was found to have no effect on triggering of TLOSR although it reduced the frequency with which acid reflux was associated with TLOSR. It is concluded that the low rate of occurrence of TLOSR in recumbent positions is unlikely to be explained by the presence of a gastric pool of liquid in proximity to the lower oesophageal sphincter.

Influence of indomethacin amphoteric gel on gastric ulcerogenicity and absorption of indomethacin in rats

Indomethacin is a potent and efficacious antiinflammatory agent. However, a limiting side effect is its ability to cause gastric ulceration. This study was designed to investigate the effects of an amphoteric gel on the gastric ulcerogenicity and pharmacokinetics of indomethacin. Oral administration (5 mg/kg) in a suspension and a gel formulation were compared to an intravenous (iv) formulation of indomethacin in rats. The iv formulation administered to rats produced large severe ulcers in some rats but not in others. In contrast, the oral suspension produced small ulcers in all rats. The difference in toxicities is attributed to a centrally mediated action as a result of high plasma levels of indomethacin following iv administration, compared to locally mediated action with the suspension, resulting from local high concentrations of indomethacin on the apical epithelial surface because of the presence of indomethacin crystals. Oral administration of the gel formulation did not result in any gastric ulceration and improved the bioavailability of indomethacin to 115.5%, compared with 68.2% for the suspension. The reduced gastrointestinal toxicity of indomethacin in the gel was attributed to the gel's ability to dissolve indomethacin, preventing the localized high concentration observed with the suspension and possibly providing a gastric protectant phospholipid. The gel formulation doubled the oral bioavailability and the tmax of indomethacin compared to the suspension but did not affect the half-life. The results indicate that the local irritant effect of indomethacin, in rats, can be reduced by appropriate formulation design and suggest that the ulcerogenicity index for indomethacin can be improved by the use of an amphoteric gel formulation.

Neural reflex of the canine pylorus to intraduodenal acid infusion

In 29 chloralose-urethane anesthetized dogs, a manometric assembly was inserted through a gastrostomy to monitor pressure of the pyloric region with a sleeve sensor. Antral and duodenal contractions were monitored with both manometric sideholes and serosal strain gauges. An additional tube channel allowed intraduodenal infusions 1-2 cm aborad from the pylorus. Intraluminal infusion of hydrochloric acid (0.1 N, 0.92 ml/min, for 2 min) reproducibly caused activation of motor activity in the pyloric region and peristaltic duodenal activity. Proximal duodenal activity probably contributed to the total phasic response recorded in the pylorus region. Excitatory responses could also be elicited by infusion of phenyl-biguanide (stimulant of sensory nerve endings), but not by control infusions with diluent (Krebs' buffer or saline). The motor response of the pyloric region to intraduodenal acid was blocked by intraduodenal application of 2% xylocaine. Atropine (30 micrograms/kg i.v. and 100 micrograms i.a.) or hexamethonium (10 mg/kg and 1 mg i.a.) markedly reduced or blocked the acid-induced pyloric motor response of this region but propranolol (1.0 mg/kg i.v. and 100 micrograms i.a.), phentolamine (1.5 mg/kg i.v. and 100 micrograms i.a.), or naloxone (200 micrograms/kg and 20 micrograms i.a.) had no effect. We believe these observations show the existence of a reflex from the duodenum to the pylorus in response to intraluminal stimuli mediated by a chain of cholinergic nerves. In the dog, endogenous opioid peptides do not contribute to the excitatory reflex pathway activated by intraduodenal acid or phenyl-biguanide. As intraluminal acid in the duodenum activates this reflex, it may play a role in the physiologic and pathophysiologic role of gastric emptying in this species.

Healing and relapse of severe peptic esophagitis after treatment with omeprazole

We have studied the response of erosive or ulcerative esophagitis to treatment with omeprazole and its subsequent relapse on cessation of therapy in 196 patients. In the first phase of the study omeprazole (20 or 40 mg daily) was compared with placebo in 64 patients. After 4 wk there was endoscopic healing in 81% (25 of 31) of omeprazole-treated patients and in only 6% (2 of 32) of placebo-treated patients. Endoscopic healing of esophagitis was accompanied by symptom relief and histologic healing of ulceration. In the second (dose finding) phase a further 132 patients were randomized to omeprazole (20 or 40 mg daily) and endoscopic healing was assessed. In patients with the mildest grade of ulcerative esophagitis (grade 2), healing occurred at 4 wk in 87% receiving 20 mg and in 97% receiving 40 mg. In patients with grade 3 esophagitis, 67% (20 mg) and 88% (40 mg) were healed. Less than half the patients with grade 4 esophagitis (Barrett's ulcers or confluent ulceration) healed with either 20 mg (48%) or 40 mg (44%). Regression analysis in the 164 omeprazole-treated patients showed no evidence that healing was influenced by factors other than severity of esophagitis at entry and omeprazole dose. In phase 3 of the study the rate of endoscopic relapse was determined in 107 endoscopically healed patients after stopping omeprazole. Erosive or ulcerative esophagitis recurred in 88 of 107 (82%) by 6 mo. Neither initial dose, grade of esophagitis, nor smoking was shown to influence relapse rate. Omeprazole is a highly effective treatment for peptic esophagitis. The 40-mg/day dosage produces endoscopic healing slightly more quickly than the 20-mg/day dosage, and the initial endoscopic gradings are of prognostic value. Relapse occurs rapidly when treatment is stopped.

Stimulation of pyloric motility by intraduodenal dextrose in normal subjects

Recent studies suggest that the pylorus may play an important role in the regulation of the gastric emptying of nutrient liquids in man. Dextrose solutions in the range 5-25 g/dl have been reported to empty from the human stomach at a constant caloric rate of 2.1 kcal/min. This study examined, in 12 healthy volunteers, the effects of intraduodenal dextrose on pyloric motility. Dextrose solutions, 5, 10, 15, and 25 gde/dl and saline solutions, 0.9 and 2.7 g/dl were infused into the duodenum at 4 ml/min for 10 minutes. Antral, pyloric, and duodenal motility were monitored with sideholes and a sleeve sensor positioned across the pylorus. Significant increases in the rate of isolated pyloric pressure waves and in basal pyloric pressure were seen with 15 and 25 g/dl dextrose (p less than 0.02) and 2.7 g/dl saline (p less than 0.05). The intensity and duration of the phasic and tonic pyloric motor responses to intraduodenal dextrose were dose dependent and correlated directly with the rate of calorie delivery (p less than 0.005 for each parameter). Intraduodenal delivery of dextrose at a rate in excess of 2.1 kcal/min stimulates both phasic and tonic pyloric contraction. These changes in pyloric motility may contribute to the close regulation of the emptying of dextrose from the stomach.

Topography and measurement of pyloric pressure waves and tone in humans

The topography of human pyloric pressure is ill defined, and previous studies of pyloric motility in humans have given conflicting results. A detailed profile of pyloric pressure has been recorded in seven healthy volunteers using a manometric assembly with 13 side holes spaced at 3-mm intervals on reverse aspect of a 3.5-cm long sleeve sensor. After a fasting control period of 40 min, recordings were made for 40 min during intraduodenal infusion of a lipid emulsion. Two major patterns of pressure waves were seen during the fasting control period, namely pressure waves confined to a narrow pyloric zone (isolated pyloric pressure waves) and pressure waves that were less localized and involved the antrum and/or duodenum. During lipid infusion the motility pattern was dominated by isolated pyloric pressure waves and localized pyloric tone. Ninety-two percent of the isolated pyloric pressure waves recorded by the sleeve were recorded by only one or two side holes, consistent with a phasically active zone less than 9 mm in length. Pyloric tone was confined to an even narrower zone and was most often recorded by only one side hole. When both tone and isolated pyloric pressure waves occurred together, they were recorded by the same side holes. By comparison with the side holes, the sleeve recorded 89% of isolated pyloric pressure waves and 98% of nonlocalized waves and recorded pyloric tone with a moderate sensitivity but high specificity. The technical challenge of recording localized pyloric contraction is considerable, and much of the conflict between previous studies of the human pylorus is explicable on methodological grounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of general anaesthesia on transient lower oesophageal sphincter relaxations in the dog

This report investigates the hypothesis that gastro-oesophageal flow is modulated by central nervous activity. The hypothesis was examined using the canine model in which gastro-oesophageal flow was stimulated by gastric insufflation of air at 80 ml/min and central nervous depression was produced with the anaesthetic agents thiopentone, nitrous oxide and halothane. Duplicate paired studies were performed in four dogs, either unsedated or anaesthetized. Gastro-oesophageal flow was assessed manometrically by a sleeve catheter assembly and by pH electrode. Gastric compliance was assessed by inflation of a thin-walled, plastic bag. Transient lower oesophageal sphincter relaxation, the dominant mechanism of retrograde trans-sphincter flow in unsedated animals, was abolished by general anaesthesia. Retrograde flow of gas across the lower oesophageal sphincter in anaesthetized animals eventually occurred, but only after massive gastric distension and elevation of gastric pressure to lower oesophageal sphincter pressure. The effects observed could not be explained by a direct action of anaesthetic on the lower oesophageal sphincter or on the gastric wall. It is proposed that general anaesthesia results in blockade of the neural pathway responsible for transient lower oesophageal sphincter relaxation by withdrawal of facilitative higher centre activity. The findings have implications for the use of sedation in experimental studies on factors which control gastro-oesophageal reflux, and clinical application to the risk of tracheal aspiration during general anaesthesia.

Inhibitory opioid receptors in canine pylorus

In 18 anesthetized dogs, antroduodenal and pyloric motility was monitored in vivo by a sleeve and perfused side-hole manometric assembly and by antral and duodenal serosal strain gauges. Close intra-arterial injection to the pylorus of dynorphin-(1-13) (Dyn) for kappa-receptors, [D-Pen2,5]enkephalin (DPen2,5-Enk) for delta-receptors, and [N-Me-Phe3-D-Pro4]morphiceptin (PL017) and [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAGO) for mu-receptors showed no excitatory effect in the pylorus. When pyloric motor activity was increased by duodenal field stimulation 3-5 cm aboaad from the pylorus, Dyn greater than DPen2,5-Enk greater than DAGO produced a dose-dependent inhibition of the pyloric motor activity. Naloxone (200 micrograms/kg iv and 20 micrograms ia) had no effect on the pyloric excitation due to duodenal field stimulation, but it reduced the inhibitory response of intra-arterially injected opioids. In addition, opioid binding ([3H]diprenorphine) in microsomal and mitochondrial fractions from the inner circular muscle ring of the pylorus showed a distribution similar to the neuronal marker [3H]saxitoxin but no correlation to the plasma membrane marker 5'-nucleotidase. These results suggest the existence of inhibitory opioid receptors (kappa- and delta-receptors) on excitatory neurons in the intestinal neuronal pathway, which activates the canine pylorus.

Intestinal 5-fluorouracil absorption: use of Ussing chambers to assess transport and metabolism

We have employed an in vitro system to study transport and metabolism of organic molecules by gastrointestinal tissues. Such a system would aid in the evaluation of the potential for oral delivery of organic molecules. Transport and metabolism of 5-fluorouracil (5-FU) were studied using rabbit intestinal preparations. Unidirectional fluxes and metabolism were measured in vitro in Ussing chambers under short-circuit conditions. Results from these studies reveal that in ileum, proximal, and distal colon, steady-state fluxes of 5-FU (10 microM added to both bathing solutions) are established after 30 min and remain constant for at least 110 min. Transport of 5-FU under "sink" conditions with 10 microM 5-FU present in the mucosal or serosal bathing solution alone demonstrated similar rates of transport as under "nonsink" conditions. The concentration dependence of 5-FU fluxes indicates that the mucosal (m)-to-serosal (s) flux is composed of both a saturable and a linear component over the range of 1-100 microM in the ileum, whereas the s-to-m flux in the ileum and both fluxes in the colon are linear functions of concentration. Over the concentration range employed and the time course of these studies, 5-FU had no effect on the electrical properties of the ileum or colon. In the ileum, the m-to-s but not the s-to-m flux of 5-FU was reduced by (1) serosal ouabain (0.1 mM); (2) reduction of the bathing solution Na concentration; and (3) addition of uracil, thymine, thymidine, uridine, 2-deoxyuridine, or uridine-5'-monophosphate.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of thallium poisoning on intellectual function

A student of chemistry was treated for thallium poisoning. Seven months after his ingestion of thallium, intelligence tests were performed on the patient and his non-identical twin brother, who was of similar educational background. These indicated severe deterioration in intellectual function of the patient, particularly in memory and performance abilities. Tests 13 months after ingestion showed little general improvement.

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.

Extrinsic and intrinsic neural control of pyloric sphincter pressure in the dog

1. In chloralose-urethane-anaesthetized dogs a manometric assembly was inserted via a gastrostomy to monitor pyloric pressure with a sleeve sensor. Antral and duodenal contractions were monitored with both manometric side holes and serosal strain gauges. 2. Subserosal silver wire electrodes were placed in the antrum 5 cm orad and the duodenum 3 cm aborad to the pylorus to facilitate field stimulation of intramural nerves. 3. The pylorus exerted spontaneous tone (10.8 +/- 4.8 mmHg) with phasic contractions occurring at a rate varying from 1-5 min-1 and, at times, with a superimposed higher frequency up to 15 min-1. Atropine (30 micrograms kg-1 I.V. and 10 micrograms I.A.) reduced and tetrodotoxin (50-100 micrograms I.A.) enhanced the phasic activity significantly. 4. Bilateral cervical vagal section had no consistent influence on pyloric motility. 5. Stimulation of the distal ends of the cervical vagal nerves at low frequencies (0.2-0.5 Hz, 1-3 ms, 20 V) induced phasic pyloric contractions, which were abolished by atropine or hexamethonium (10 mg kg-1 I.V. and 1 mg I.A.). Higher frequencies (greater than 0.7 Hz) of stimulation inhibited both phasic and tonic contractions and this inhibition was unaffected by atropine, hexamethonium, phentolamine (1.5 mg kg-1 I.V. and 100 micrograms I.A.) or propranolol (1 mg kg-1 I.V. and 100 micrograms I.A.). All neural responses were blocked by tetrodotoxin (50-100 micrograms I.A.). 6. Duodenal field stimulation (0.2-5 Hz, 0.5 ms, 40 V) induced strong phasic and tonic contractions in the pylorus. This excitation was blocked by atropine, hexamethonium, tetrodotoxin (50-100 micrograms I.A.) or duodenal transection orad to the stimulating electrodes. 7. Antral field stimulation (0.5-1 Hz, 0.5 ms, 40 V) completely abolished phasic activity in the pylorus and reduced tonic activity, regardless of whether the contractile activity was spontaneous or induced by neural stimulation. This inhibitory action was unaffected by atropine, hexamethonium or propranolol but was blocked by tetrodotoxin and antral transection aborad to the stimulating electrodes. Phentolamine attenuated the inhibitory effect of antral field stimulation on pyloric motility. 8. It is concluded that the distal canine pylorus exhibits myogenic tone and phasic activity which is modulated by extrinsic and intrinsic nerve pathways. Vagal nerves contain fibres, activated by different stimulus parameters which can either excite or inhibit pyloric activity. Activation of antral nerves inhibits pyloric activity, with both non-adrenergic, non-cholinergic and phentolamine-sensitive pathways contributing to this inhibitory response.(ABSTRACT TRUNCATED AT 400 WORDS)

Upper esophageal sphincter function during deglutition

Upper esophageal sphincter function was investigated during swallows of graded volumes in 8 normal volunteers. Concurrent recordings of video-fluoroscopic and manometric studies were obtained and correlated with each other by means of a videotimer. Maximal upper esophageal sphincter (UES) pressure was typically located 1.5 cm distal to the air-tissue interface between the hypopharynx and the proximal margin of the sphincter. The region in which UES pressure was greater than or equal to 50% maximal averaged 1.0 cm in length. Thus, the physiologic high-pressure zone of the UES corresponds in size and location to that of the cricopharyngeus muscle. Fluoroscopic analysis of sphincter movement indicated that the sphincter high-pressure zone moved 2.0-2.5 cm orally during swallowing and that the magnitude of the orad movement was directly related to the volume of barium swallowed. The maximal anterior-posterior diameter of sphincter opening during a swallow ranged from 0.9 to 1.5 cm and was also directly related to the volume swallowed. The intervals of UES opening and relaxation increased significantly with increasing bolus volume; the duration of UES relaxation ranged from a mean of 0.37 s for dry swallows to 0.65 s for 20-ml swallows. Thus, the dynamics of UES function during deglutition are dependent upon the volume of the swallowed bolus. Larger bolus volumes are accommodated by both an increased diameter of sphincter opening and by prolongation of the interval of sphincter relaxation. Analysis of the timing of other reference points within the pharyngeal swallow sequence indicated that as the manometric interval of UES relaxation increased, the period of laryngeal elevation was prolonged, the UES relaxed earlier and contracted later, and the interval between the onset of laryngeal elevation and hypopharyngeal contraction increased.

Relationship of the motor activity of the antrum, pylorus, and duodenum to gastric emptying of a solid-liquid mixed meal

The postprandial motor activity of the antrum, pylorus, and duodenum in 15 healthy volunteers was compared with the profiles of emptying of the solid and liquid components of a meal. The liquid component of the meal emptied rapidly in an exponential manner, whereas the solid remained in the fundus of the stomach until approximately 80% of the liquid had emptied and then emptied in a linear manner. The onset of solid emptying was associated with an increase in the rate of occurrence of antral pressure waves (p less than 0.05), and the half-time for solid emptying (t1/2 - lag period) was inversely correlated (p less than 0.05) with the rate of coordinated contractions involving the antrum. The substitution of 25% dextrose in normal saline as the liquid component of the meal increased the half-time for liquid emptying from a median of 8 to 40 min (p less than 0.01), increased the lag period for solid emptying from 40 to 87 min (p less than 0.01), and increased the rate of occurrence of isolated pyloric pressure waves during the solid lag phase from 7 to 58/h (p less than 0.05), but did not affect the slope of solid emptying or the rate of coordinated contractions involving the antrum during the solid emptying period.

Motor activity of the gastric antrum, pylorus, and duodenum under fasted conditions and after a liquid meal

Because the mechanisms that control the movement of food and digestive juices across the human pylorus are not completely understood, the aim of this study was to document the normal patterns of pressure activity in the antrum, pylorus, and duodenum and the associated pH changes in 9 healthy volunteers. Studies were carried out under fasting conditions and after ingestion of 300 ml of chocolate milk, using a unique 11-channel intraluminal probe that incorporated a sleeve sensor positioned across the pylorus and pH electrodes situated in the terminal antrum and proximal duodenum. The most common motor pattern recorded under fasting conditions consisted of regular coordinated contractions, most of which (a) involved the antrum and duodenum, (b) showed evidence of propagation through two or more adjacent channels, and (c) were associated with transient reductions in duodenal pH and transient elevations in antral pH. Ingestion of milk changed the motor pattern to one that was composed of pressure waves, which were confined to the pylorus with few or no pressure waves in the terminal antrum or proximal duodenum. Isolated pyloric pressure waves were gradually replaced by propagated antroduodenal contractions, which eventually occurred at a regular frequency that was higher than that observed under fasting conditions. After ingestion of milk, only the coordinated contractions were associated with transient reductions in duodenal pH. Isolated pyloric pressure waves were also observed under fasting conditions just before or just after phase III of the migrating motor complex, and 17% of these were accompanied by episodes of duodenal acidification.

Antropyloroduodenal motor responses to intraduodenal lipid infusion in healthy volunteers

The delivery of lipid to the duodenum has been shown to slow gastric emptying and to increase the resistance to gastric outflow. To investigate mechanisms responsible for these effects, we have recorded antropyloroduodenal motility in nine healthy volunteers during alternate intraduodenal infusions of normal saline and triglyceride emulsion (Intralipid 10%). During the lipid infusions there were reproducible, major changes in the patterns of motility. Pressure waves, apparently isolated to the pylorus, usually started within 10 min of initiation of the lipid infusion. After 20-25 min of lipid infusion these waves occurred at median rates of 2.4 and 2.8/min (1st and 2nd lipid infusions, respectively); these rates were significantly greater (P less than 0.05) than the median rates (all less than or equal to 0.4/min) observed during the equivalent period of the succeeding saline infusions. During 10 of 22 lipid infusions, isolated pyloric pressure waves were associated with sustained pyloric tone. Infusion of lipid into the duodenum suppressed antral pressure waves in all subjects and initiated brief periods of regular duodenal contractions during 11 of 22 infusions. These studies have demonstrated alterations of antropyloroduodenal motor patterns in response to changes in the duodenal luminal content. The effects on antral and pyloric motility are probably of importance in the regulation of transpyloric flow by nutrients in the duodenal lumen.

IIB von Willebrand's disease: pathogenetic and therapeutic studies

Infusion of 1-deamino-(8-D-arginine)-vasopressin (DDAVP) into patients with IIB von Willebrand's disease (vWD) has been reported to induce thrombocytopenia. In some families with this disorder thrombocytopenia is present even in the resting state. We have investigated the basis of this chronic thrombocytopenia in one such patient by performing platelet recovery and survival studies. Increased platelet consumption was suggested by a decrease in platelet recovery (40.5%, normal 45%) and mean platelet survival (112 h, normal range 144-224 h). In addition, we have administered test infusions of DDAVP and observed the effect on bleeding time and platelet count. DDAVP caused a decrease in the median platelet count from 86 x 10(9)/l (range 30-221) to 60 x 10(9)/l (range 5-144), the individual decline in the nine subjects ranging from 12% to 84% compared to the pretreatment values. Formation of platelet aggregates was observed in all patients following DDAVP. The bleeding time was prolonged before DDAVP in all patients and lengthened further in two after the infusion. However, partial correction of the bleeding time was seen in three and normalization in one patient following DDAVP infusion. Two IIB vWD patients were treated with virus-inactivated cryoprecipitate (Ristofact). Infusion of cryoprecipitate was followed by rapid appearance of all but the largest vWF multimers in plasma and did not affect the platelet count. The bleeding time was normalized in one patient but remained prolonged in the other. In conclusion, in IIB vWD patients virus-inactivated cryoprecipitate is the treatment of choice in the case of bleeding. Infusion of DDAVP might be effective in a subset of IIB vWD patients that has yet to be characterized.