Biomedical subjects

J Dent

Publications and source records attributed to J Dent.

At least 199 records · Page 11Linked to original sources

PubMed1990

Luminographic detection of von Willebrand factor multimers in agarose gels and on nitrocellulose membranes.

Two methods for visualization of vWf multimers were compared with respect to sensitivity and detection of normal vWf and vWd variants IIA, IIB, IIC, IID, IIE, and IIF. Autoradiography and luminography after electrotransfer of vWf multimers onto nitrocellulose showed comparable sensitivity with vWf:Ag detectable after 1:500 dilution of normal plasma. The least sensitive method was luminography in agarose gels with vWf:Ag detectable after 1:300 dilution of normal plasma. No difference existed in the banding patterns of plasmas from patients with variant vWd.

Autoradiography↗

PubMed1990

Hyperglycaemia slows gastric emptying in type 1 (insulin-dependent) diabetes mellitus.

In 10 patients with Type 1 (insulin-dependent) diabetes mellitus gastric emptying of a digestible solid and liquid meal was measured during euglycaemia (blood glucose concentration 4-8 mmol/l) and during hyperglycaemia (blood glucose concentration 16-20 mmol/l). Gastric emptying was studied with a scintigraphic technique and blood glucose concentrations were stabilised using a modified glucose clamp. Patients were also evaluated for gastrointestinal symptoms, autonomic nerve function and glycaemic control. When compared to euglycaemia, the duration of the lag phase before any of the solid meal emptied from the stomach (p = 0.032), the percentage of the solid meal remaining in the stomach at 100 min (p = 0.032) and the 50% emptying time for the solid meal (p = 0.032) increased during hyperglycaemia. The 50% emptying time for the liquid meal (p = 0.042) was also prolonged during the period of hyperglycaemia. These results demonstrate that the rate of gastric emptying in Type 1 diabetes is affected by the blood glucose concentration.

Adult↗

PubMed1990

The effect of terminal ileal triglyceride infusion on gastroduodenal motility and the intragastric distribution of a solid meal.

The infusion of triglyceride emulsions into the terminal ileum in concentrations that approximate those found in malabsorption results in the slowing of gastric emptying. The aim of this study was to characterize the changes in gastroduodenal motility responsible for this effect. Antropyloroduodenal pressures in 8 healthy volunteers were recorded with a manometric assembly incorporating a sleeve sensor across the pylorus and side holes in the antrum and duodenum. Each subject ingested a 100-g, 99m Tc-labeled solid meal; when approximately 25% of the meal had emptied from the stomach, a triglyceride emulsion (20% Intralipid) was infused into the terminal ileum at 1 ml/min for 45 min. Gastric emptying slowed markedly 15-30 min after the start of the lipid infusion (p = 0.01), and there was retrograde movement of the solid meal from the distal to the proximal portion of the stomach. During lipid infusion, there was a decrease in antral (p = 0.01), duodenal (p less than 0.05), and propagated antropyloroduodenal pressure waves (p less than 0.05) and an increase in isolated pyloric pressure waves (p less than 0.05). The rate of gastric emptying correlated with antral pressure waves (r = 0.92, p less than 0.001), duodenal pressure waves (r = 0.80, p less than 0.01), and propagated pressure waves (r = 0.88, p = 0.0025) and correlated inversely with the number of isolated pyloric pressure waves (r = -0.60, p = 0.05). The changes in antral, pyloric, and duodenal motility and the intragastric redistribution of a solid meal associated with ileal lipid infusion are likely to contribute to the delay in gastric emptying caused by this stimulus.

Adult↗

PubMed1990

Gastroduodenal motility during the delayed gastric emptying induced by cold stress.

We have assessed the changes in gastroduodenal motility responsible for the delay in gastric emptying produced by cold stress. Antropyloroduodenal pressures were recorded in 7 healthy volunteers, concurrent with scintigraphic measurement of gastric emptying. The manometric assembly incorporated a sleeve sensor located across the pylorus and side holes in the antrum and the duodenum. When approximately 25% of a 100-g 99m Tc-labeled ground beef burger had emptied from the stomach, a standardized cold pressor test was applied. This consisted of 60-s immersions of the left hand in iced water (4 degrees C), with 15-s rest periods between immersions, for up to 20 min. Cold stress was associated with slowed emptying from the total stomach (median, 17% before stress vs. 2% during stress; p less than 0.01) and the proximal stomach (9% before vs. 3% during; p less than 0.01). Retrograde movement of the solid meal from the distal to the proximal stomach was observed in 4 subjects. Cold stress increased the number of isolated pyloric pressure waves (p less than 0.05), and decreased the number of antral (p less than 0.01) and propagated antropyloroduodenal pressure waves (p less than 0.05). Phase 3-like duodenal activity occurred in 2 subjects during the first 5 min of stress; otherwise there was a reduction in the number of duodenal pressure waves during stress (p less than 0.05). Basal pyloric pressure was not elevate before, during, or after stress. We conclude that in addition to the previously reported antral inhibition, cold stress is associated with changes in pyloric and duodenal motility and, in some subjects, in the intragastric distribution of food. These modifications in gastroduodenal motility are likely to contribute to the delay in gastric emptying produced by this stimulus.

Adolescent↗

PubMed1990

The effect of naloxone on lipid-induced pyloric motor response in humans.

This study examines whether opioid receptors are involved in the mediation of the pyloric motor response to intraduodenal lipid infusion. Antral, pyloric, and duodenal manometry was performed in seven healthy volunteers with a sleeve/multiple side-hole manometric assembly. Triglyceride emulsion and normal saline were infused alternately into the duodenum through the manometric assembly for two 30-minute periods each. Naloxone was then administered as an IV bolus, 40 micrograms/kg, followed by an infusion of 60 micrograms.kg-1.h-1 that was continued during testing of the duodenal infusates. Before naloxone administration, intraduodenal lipid produced significant increases in the rate of isolated pyloric pressure waves and basal pyloric tone when compared with saline (P = 0.009 and 0.027, respectively). The pyloric motor responses were unchanged after administration of naloxone, indicating that in humans, naloxone-sensitive opioid mechanisms are not involved in the mediation of lipid-induced pyloric motor responses.

Adult↗

PubMed1990

Surgery and chemotherapy in the management of placental site tumor.

Since 1977 we have managed seven cases of placental site trophoblastic tumor. All patients were treated with hysterectomy. Three patients had preoperative chemotherapy without evidence of response. One of three patients presenting with no evidence of extrauterine spread and one of four presenting with extrauterine pelvic disease have died from metastatic disease on recurrence. One patient with pelvic disease and lung metastases at diagnosis has residual lung nodules, presumed necrotic, 47 months after completing chemotherapy. She received etoposide, methotrexate, and actinomycin D (EMA) alternating weekly with cyclophosphamide and vincristine (CO). Although surgical excision of placental site tumor remains the treatment of choice, EMA/CO chemotherapy may produce the occasional long-term survivor.

Adult↗

PubMed1990

Pyloric motor function during emptying of a liquid meal from the stomach in the conscious pig.

1. In six conscious pigs antral, pyloric and duodenal pressures were recorded with a 5.5 cm sleeve sensor and multiple perfused side holes. The manometric assembly was positioned by dual point transmucosal potential difference measurement. Gastric emptying was measured by drainage of the proximal duodenum through a Thomas cannula. Pressures were correlated with emptying of ingested radiolabelled 5% dextrose. Alteration of emptying was produced by infusion into the more distal duodenum of nutrient and non-nutrient solutions of differing osmolalities. 2. Motor activity of the pylorus and antrum was stimulated by ingestion and modulated by intraduodenal infusion. Duodenal infusion of normal saline was associated with antro-pyloric pressure waves and rapid emptying of the ingested liquid. Duodenal infusion of dextrose, fatty acid, amino acids and hyperosmolar saline was associated with stimulation of isolated pyloric pressure waves, suppression of antral pressure waves and slowing of gastric emptying. 3. The dose-response relationship of these effects was investigated using varying rates of intraduodenal dextrose infusions. The emptying rate of the ingested liquid was inversely related to the rates of delivery of dextrose to the duodenum, directly related to the rate of antro-pyloric pressure waves and inversely related to the rate of isolated pyloric pressure waves. 4. Clearly defined episodes of pulsatile flow produced slightly more than half of the total emptying that occurred. This pulsatile flow was intimately associated in time with antro-pyloric pressure waves. Sequences of isolated pyloric pressure waves were associated with near cessation of emptying. When there were periods of absent pyloric antral pressure waves, flow rates intermediate between the rapid emptying of pulsatile flow during antro-pyloric pressure waves and the near cessation of flow during isolated pyloric pressure waves occurred. 5. The findings suggest a major role for the pylorus in the control of emptying of liquids from the stomach, both as a component of an antro-pyloric peristaltic pump and as a resistor to transpyloric flow during nutrient and hyperosmolar stimulation of duodenal receptors.

Animals↗

PubMed1990

Control of belching by the lower oesophageal sphincter.

The mechanism that controls venting of gas from the stomach into the oesophagus was studied manometrically in 14 healthy subjects. The stomach was distended abruptly with one litre of carbon dioxide. Gas reflux was characterised by an abrupt increase in basal oesophageal body pressure to intragastric pressure. Reflux of gas from the stomach into the oesophagus occurred during transient lower oesophageal sphincter relaxations that generally had a pattern distinctly different from swallow-induced lower oesophageal sphincter relaxation. Thus, at the onset of an episode of gas reflux lower oesophageal sphincter pressure had relaxed to 3 mmHg, or less, in 96% of instances. After gas loading of the stomach the prevalence of gas reflux was significantly less when the subjects were supine (1.2/10 min) than when they were sitting (6.8/10 min) (p less than 0.001). The lower oesophageal sphincter relaxations associated with most episodes of gas reflux had a distinctive pattern that resembled those of the lower oesophageal sphincter relaxations associated with acid gastro-oesophageal reflux.

Adult↗

PubMed1990

Evaluation of patterns of human antral and pyloric motility with an antral wall motion detector.

We have examined the hypothesis that isolated pyloric pressure waves occur in the absence of even low-amplitude antral contractions. Antropyloroduodenal motility was recorded in seven healthy adult volunteers. A sleeve/side-hole manometric assembly was positioned across the pylorus with the aid of measurements of transmucosal potential difference. A new sensor consisting of an elliptical wire transducer 2.5 cm long and 1.5 cm in transverse diameter was incorporated into the assembly above the sleeve. This sensor was designed to detect nonlumen-occluding antral contractions. Motility was studied for 45 min under each of three conditions: 1) fasting, 2) after ingestion of a 100-g beef burger, and 3) during and after a 15-min intraduodenal infusion of 25% dextrose at a rate of 4 ml/min. Overall, only 51% of antral transducer deflections were associated with a change in antral side-hole pressures. Eighty-nine percent of antral side-hole pressure waves were associated with an indication of antral wall motion. Of the pressure waves recorded by the sleeve classified as isolated pyloric pressure waves, none was associated with antral transducer deflection during fasting, 1.1% after intraduodenal dextrose, and 18% after the solid meal. Antral contractions were detected by the wall motion detector with greater sensitivity than antral side holes, possibly reflecting the occurrence of nonlumen-occluding antral contractions. With some exceptions during solid gastric emptying, manometrically defined isolated pyloric pressure waves appear to represent truly localized contraction.

Adult↗

PubMed1990

Human lower esophageal sphincter pressure response to increased intra-abdominal pressure.

We studied the effects of increased intra-abdominal pressure on the lower esophageal sphincter (LES) pressure in 15 healthy subjects. The role of the diaphragm in the genesis of LES pressure during increased intra-abdominal pressure was determined by measuring diaphragm electromyogram (EMG). The latter was recorded using bipolar intraesophageal platinum electrodes that were placed on the nonpressure sensing surface of the sleeve device. We also measured the LES pressure response to increased intra-abdominal pressure during inhibition of the smooth muscles of the LES by intravenous atropine (12 micrograms/kg). Straight-leg raising and abdominal compression were used to increase intra-abdominal pressure. Our results show that the increase in LES pressure during straight-leg raising is greater than the increase in gastric pressure. During abdominal compression, the rate of LES pressure increase is faster than that of the gastric pressure, suggesting an active contraction at the esophagogastric junction. The increase in LES pressure during periods of increased intra-abdominal pressure is associated with a tonic contraction of the crural diaphragm as demonstrated by EMG recording. Atropine inhibited the resting LES pressure by 50-70% in each subject but had no effect either on the peak LES pressure attained during increased intra-abdominal pressure or tonic crural diaphragm EMG. We conclude that 1) there is an active contraction at the esophagogastric junction during periods of increased intra-abdominal pressure and 2) tonic contraction of the crural diaphragm is a mechanism for this LES pressure response.

Abdomen↗

PubMed1990

Response of canine lower esophageal sphincter to gastric distension.

The aim of this study was to localize the region of the stomach responsible for triggering distension-induced transient lower esophageal sphincter relaxation (TLESR). The canine stomach was partitioned into subsegments by a row of buttressed sutures. This separated either the fundus from the lesser curve or the proximal stomach from the antrum. After 1 mo each region was progressively distended while gastroesophageal pressures were monitored. At the time of the first TLESR, gastric wall tension was estimated from the bag pressure and volume. Distension of the intact stomach, lesser curve, or proximal stomach in 12 dogs produced a progressive increase in lower esophageal sphincter (LES) pressure, which was interrupted at low gastric wall tension (29, 35, and 40 mmHg.cm, respectively) by a superimposed TLESR. Background LES pressure fell progressively with distension of the antrum but was unchanged by distension of the fundus alone. Both the fundus and antrum had significantly higher thresholds for triggering TLESR (96 and 105 mmHg.cm). In another two dogs truncal vagotomy performed at the time of gastric partitioning prevented both the change in background LES pressure, and the triggering of TLESR, associated with proximal gastric and antral distension. We conclude that the subcardiac region of the stomach is primarily responsible for triggering TLESR induced by distension and that the effect on background LES pressure depends on the region distended.

Animals↗

PubMed1990

Relationship between fluctuations of pH and pressure in the human stomach and duodenum.

The normal patterns of pressure activity in the antrum, pylorus and duodenum and associated pH changes were monitored in 9 healthy volunteers under fasted conditions and after ingestion of 300 ml of chocolate milk. The manometric assembly incorporated three side holes in the antrum, four side holes in the duodenum, 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 co-ordinated contractions, most of which involved the antrum and duodenum, showed evidence of propagation and was associated with transient decreases in duodenal pH and transient increases in antral pH. Ingestion of milk changes 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 antropyloroduodenal contractions which were associated with transient decreases in duodenal pH. Isolated pyloric pressure waves were not associated with episodes of duodenal acidification under fed conditions.

Adult↗

PubMed1990

Australian clinical trials of omeprazole in the management of reflux oesophagitis.

Two multicentre clinical trials of omeprazole in peptic oesophagitis were recently completed in Australia. In the first trial, omeprazole, 20 or 40 mg daily (n = 31), was compared with placebo (n = 32) in 63 patients. After 4 weeks, 81% of the omeprazole-treated patients were healed, as determined endoscopically, compared with 6% of the placebo-treated patients (p less than 0.0001). When the two doses of omeprazole were compared, there was a significant therapeutic advantage for the 40 mg dose at 4 weeks but by 8 weeks there was no significant difference between the two doses. This study included a 6-month surveillance phase in 107 endoscopically healed patients after cessation of omeprazole therapy. By 6 months, erosive or ulcerative oesophagitis had recurred in 82% of these patients. In the second trial, 165 patients with erosive or ulcerative oesophagitis were first healed with omeprazole, 20 mg daily. Of these patients, 159 were then enrolled in a maintenance therapy trial and randomized to three groups: ranitidine, 150 mg b.i.d., omeprazole, 20 mg daily, or omeprazole weekend therapy (i.e. omeprazole, 20 mg daily, on Friday, Saturday and Sunday only). Patients were followed for a maximum period of 12 months or until relapse. Neither ranitidine nor weekend therapy with omeprazole was effective in maintaining patients in remission. However, omeprazole, 20 mg daily, was a highly effective maintenance therapy with 89% of patients in remission after 12 months compared with only 25 and 32% for ranitidine and weekend omeprazole, respectively. All three regimens were well tolerated.

Australia↗

PubMed1990

Current and future drugs for acid-peptic disease: a plethora of opinions on possible mechanisms of action.

Sixty-seven invited participants involved in the development, evaluation, and use of therapies for acid-peptic disorders participated in a meeting to discuss the scientific basis for healing actions of ulcer drugs and the prospects for future developments ("Realities of Mucosal Protection in the Upper Gastrointestinal Tract," Lausanne, Switzerland, November 8-10, 1987). Eighty-one key statements were prepared and subsequently analyzed on the basis of a voting system. Of the 45 statements that dealt with existing therapies, only 3 statements showed positive consensus (agreement of two-thirds or more of voters) about mechanisms of ulcer healing. Participants agreed that both (1) hydrogen/potassium adenosine triphosphatase inhibitors and (2) histamine H2 antagonists healed ulcers solely by acid inhibition, and (3) that sucralfate works by topical action. Substantial uncertainty about the mechanisms by which bismuth compounds and antacids heal ulcers was noted as well as their wide range of effects. The mechanism of ulcer healing by prostaglandins and the clinical relevance of antiulcer effects of drugs demonstrated in acute studies with animals were also controversial. There was greater agreement among participants about unexplored drug effects that might produce ulcer healing. Of the 36 such mechanisms surveyed, the most support went to therapies aimed at enhancement of mucosal blood flow, epithelial restitution, and mucosal alkaline secretion or inhibition of luminal pepsin activity. The diversity of opinions among participants suggests a high level of empiricism in the development of ulcer healing drugs apart from those that inhibit acid secretion. This empiricism probably arises from inadequate understanding of processes of mucosal injury and repair.

Drug Design↗

PubMed1990

[Pathogenesis and treatment of Zencker's diverticulum].

The aims of this study were: 1) To measure pharyngeal and upper oesophageal function manometrically at the same time as recording video images of the patient swallowing barium, in normal controls and patients with Zenker's diverticulum, and, 2) In those patients who progressed to surgery to biopsy the cricopharyngeus and compare the findings with biopsies from normal controls. Subjects were seated in front of a fluoroscope and video images of a barium swallow were synchronised with a multichannel recording catheter which contained 3 perfused side holes 1 cm apart (situated in the pharynx) and a 4 cm long perfused sleeve pressure sensor (positioned across the upper oesophageal sphincter). The coordination of the upper sphincter with swallowing, its relaxation, the pressures generated in the distal pharynx and the maximum luminal area of the open upper sphincter, were calculated for different volumes of barium swallowed in 11 patients with a Zenker's diverticulum (mean age 71 years, range 50-99) and 9 normal controls (mean age 65 years, range 55-86). Seven patients progressed to cricopharyngeal myotomy and their biopsies were compared with biopsies from 9 normal controls. In patients with Zenker's diverticulum intrapharyngeal pressures during barium swallows were significantly greater (p less than .05) and maximal luminal areas of the open sphincter were significantly less (p less than .05) than in control patients. In patients having a cricopharyngeal myotomy, intrapharyngeal pressures and maximum luminal areas returned to normal after surgery. The cricopharyngeus muscle of patients with a Zenker's diverticulum showed significantly increased fibrosis compared with normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

Pathophysiology of gastroesophageal reflux. Lower esophageal sphincter dysfunction in gastroesophageal reflux disease.

LES dysfunction is the principal mechanism responsible for GER disease. Two main patterns of sphincter dysfunction have been identified: an abnormally high rate of transient LES relaxations, and defective basal LES pressure. Overpowering of a weak LES by pressure transients induced by straining is less common than previously thought, at least under conditions tested thus far. Current evidence suggests that LES dysfunction results primarily from defective neural control, although smooth muscle function may also be impaired. Extrinsic mechanisms, particularly the diaphragmatic crura, also appear to be important during straining. The role of hiatus hernia remains unclear but seems likely to contribute to the pathogenesis of reflux disease by impairing LES function.

Deglutition↗

PubMed1989

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.

Adult↗

PubMed1989

The effect of glucagon on esophageal peristalsis and clearance.

The effect of 0.5 mg intravenous glucagon on esophageal peristalsis and transit of water and barium was studied in nine healthy subjects by concurrent videofluoroscopy and manometry. Glucagon lowered manometric peristaltic amplitude in both mid- and distal esophagus. This reached significance (p = 0.0075) in the distal 3 cm of the esophagus 2 min after the injection. The efficiency of esophageal stripping was also reduced (increased proximal escape on fluoroscopy), and became significant (p = 0.05) at 2 min after the injection of glucagon.

Adolescent↗