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Biomedical subjects

J Dent

Publications and source records attributed to J Dent.

At least 289 records · Page 16Linked to original sources
PubMed1983

Interdigestive phasic contractions of the human lower esophageal sphincter.

The results of this study show that lower esophageal sphincter contractions occur during phases 2 and 3 of the gastric interdigestive migratory motor complex in humans. In one series of studies, esophageal, gastric, and duodenal pressures were monitored overnight for 12 h in 7 healthy, fasting subjects. A second group of 10 volunteers was studied for 12 h on two consecutive nights. Periods of gastric contraction that reached a maximum frequency of about 3/min were shown to be part of the migratory motor complex cycle because they occurred immediately before phase 3 migratory motor complex activity in the duodenum. In all subjects, gastric interdigestive contractions were accompanied by lower esophageal sphincter contractions that maintained a pressure barrier between the stomach and esophageal body. During late phase 2 and phase 3 gastric migratory motor complex activity, the lower esophageal sphincter contractions were especially vigorous. Mean basal lower esophageal sphincter pressure varied significantly during the interdigestive cycle. Lower esophageal sphincter pressure values were maximal during phase 3 of gastric migratory motor complex activity and minimal values occurred during phase 1. No episodes of gastroesophageal reflux occurred as a result of increase of intragastric pressure caused by interdigestive gastric contractions.

Adult↗
PubMed1982

Mechanisms of gastroesophageal reflux in patients with reflux esophagitis.

We evaluated the mechanisms of gastroesophageal reflux in 10 patients with reflux esophagitis and compared the results with findings from 10 controls. The patients had more episodes of reflux (35 +/- 15 in 12 hours, as compared with 9 +/- 8 in the controls) and a lower pressure of the lower esophageal sphincter (13 +/- 8 mm Hg as compared with 29 +/- 9 in the controls) (P less than 0.001). Reflux occurred by three different mechanisms: transient complete relaxation of the lower esophageal sphincter, a transient increase in intra-abdominal pressure, or spontaneous free reflux associated with a low resting pressure of the lower esophageal sphincter. In controls 94 per cent of reflux episodes were caused by transient sphincter sphincter relaxation. In the patients 65 per cent of episodes of reflux accompanied transient sphincter relaxation, 17 per cent accompanied a transient increase in intra-abdominal pressure, and 18 per cent occurred as spontaneous free reflux. The predominant reflux mechanism in individual patients varied: some had normal resting sphincter pressure and reflux that occurred primarily during transient sphincter relaxation, whereas others with low resting sphincter pressures had spontaneous free reflux or reflux that occurred during an increase in intra-abdominal pressure.

Adult↗
PubMed1981

Effect of atropine on esophageal motor function in humans.

In this study, we used a high-fidelity manometric recording system to quantitate the effects of atropine on lower esophageal sphincter (LES) pressure and primary peristalsis (1 degree P). A sleeve sensor recorded LES pressure, and seven recording orifices spaced at 3-cm intervals registered motor activity in the esophageal body. Five randomized manometric studies were done in each of five normal subjects. LES pressure and 1 degree P with wet swallows were recorded for 30 min before and 70 min after intravenous injection of saline or atropine, 3, 6, 12, and 24 micrograms/kg. We also studied the effect of atropine on LES pressure in five additional subjects, four dogs, four opossums, and six monkeys. In humans, saline and 3 micrograms/kg atropine caused no significant change in pulse rate, LES pressure, or the incidence of complete peristaltic sequences. The 6, 12, and 24 micrograms/kg atropine doses caused significant inhibition of LES pressure and the incidence of intact 1 degree P. Only the 12 and 24 micrograms/kg doses increased pulse rate. When 1 degree P occurred in the smooth muscle portion of the esophagus its appearance in the proximal portion of the smooth muscle segment was delayed for several seconds. The amplitude of 1 degree P was decreased 30-60% in the smooth muscle segment, but 1 degree P was not affected in the proximal striated muscle esophageal segment. Atropine reduced canine LES pressure substantially but caused no change in opossums or monkeys. We conclude that 1) basal LES tone in humans and dogs, unlike that of the opossum and monkey, is partially generated by cholinergic neural input, 2) cholinergic nerves elicit 1 degree P in human esophageal smooth muscle, and 3) species variation exists in esophageal responses to atropine.

Animals↗
PubMed1980

Effect of cholecystokinin-octapeptide on opossum lower esophageal sphincter.

We evaluated the action of cholecystokini-octapeptide (CCK-OP) on lower esophageal sphincter (LES) pressure in the opossum. LES pressure was recorded by an infused sleeve device that straddled the sphincter, whereas intraluminal esophageal pressure and gastric pressure were recorded via conventional manometric catheters. Progressive intravenous pulse doses of CCK-OP caused 1) graded increases in LES pressure, 2) circular and longitudinal smooth muscle contraction in esophageal body, and 3) mild increases in intragastric pressure. Pressor effect of CCK-OP on the LES was weakly antagonized by tetrodotoxin (TTX), but not by atropine, phentolamine, or pyrilamine. TTX antagonism of CCK-OP appeared to be nonspecific because TTX also partially antagonized LES contractions induced by pentagastrin, substance P, and bethanechol. We conclude that CCK-OP at doses that cause LES relaxation in other species induces LES contraction in the opossum. This pressor effect appears to be elicited by a direct action of the hormone on LES smooth muscle.

Animals↗
PubMed1980

Mechanism of gastroesophageal reflux in recumbent asymptomatic human subjects.

We investigated the mechanism of gastroesophageal reflux (GER) in 10 health volunteer subjects. Continuous recordings of intraluminal esophageal pH and pressure were obtained on two consecutive nights from 6:00 p.m. to 6:30 a.m. in each subject. During each study, the subject remained recumbent, except to eat a standardized meal after 1 h of basal recording. A manometric assembly with seven recording lumens monitored: (a) lower esophageal sphincter (LES) pressure via a sleeve device 6.5 cm in length, (b) esophageal-body motor activity, (c) swallowing activity in the pharynx, and (d) gastric pressure. An electrode 5 cm above the LES recorded esophageal pH. Sleep was monitored by electroencephalogram. All subjects showed wide variations of basal LES pressure. GER was not related to low steady-state basal LES pressure, but rather occurred during transient 5-30 s episodes of inappropriate complete LES relaxation. The inappropriate LES relaxations were usually either spontaneous or immediately followed appropriate sphincter relaxation induced by swallowing. The majority of GER episodes occurred within the first 3 h after eating. During the night LES relaxation and GER occurred only during transient arousals from sleep or when the subjects were fully awake, but not during stable sleep. After GER the esophagus was generally cleared of refluxed acid by primary peristalsis and less frequently by secondary peristalsis. Nonperistaltic contractions were less effective than peristalsis for clearing acid from the esophagus. We conclude that in asymptomatic recumbent subjects GER is related to transient inappropriate LES relaxations rather than to low steady-state basal LES pressure and also, that primary perstalsis is the major mechanism that clears the esophagus of refluxed material.

Adult↗
PubMed1979

Depressant effect of sodium nitroprusside on the lower esophageal sphincter of the opossum.

In this study, we evaluated the effect of sodium nitroprusside (SNP), a vascular smooth-muscle relaxant, on lower esophageal sphincter (LES) pressure in the opossum. Resting LES pressure was monitored with a perfused sleeve sensor which allows accurate recording of LES pressure irrespective of axial LES motion. Intravenous pulse doses and infusion doses of SNP both caused significant decreases in both blood pressure and LES pressure. Les tone, however, was more sensitive to SNP than blood pressure. For example, an SNP pulse dose of 20 microgram/kg which lowered blood pressure only about 30% virtually abolished LES tone. A similar result was obtained for an SNP infusion dose of 10 microgram/kg/min. Tachyphylaxis to SNP did not occur for repeated pulse doses to 10 microgram/kg, but did develop during a 20-min infusion of 10 microgram/kg/min. The effect of SNP on LES pressure was not antagonized by propranolol, metiamide, haloperidol, atropine, phentolamine, or tetrodotoxin. We conclude that the potent depressant effect of SNP on LES tone is due to a direct action of the drug on sphincter smooth muscle.

Animals↗
PubMed1978

Serum-SP1-pregnancy-specific-beta-glycoprotein in choriocarcinoma and other neoplastic disease.

A radioimmunoassay for a plancental glycoprotein, beta1SP1, capable of detecting 2 microgram/l of the glycoprotein in serum was used to measure concentrations of beta1,SP1 in patients with choriocarcinoma, teratoma, colonic cancer, breast cancer, and ovarian cancer. 12 out of 94 (13%) healthy men and health non-pregnant women had detectable serum-beta1SP1 concentrations. Concentrations up to 50 000 microgram/l were found in the sera of patients with hydatidiform mole, invasive mole, choriocarcinoma, and malignant teratoma. beta1-glycoprotein concentrations were generally much lower than corresponding concentrations of chorionic gonadotrophin which is the most reliable marker for trophoblastic tumours. In a few cases, however, beta1-glycoprotein measurements may be useful in the detection of minimal residual tumour. The slightly raised values found in some patients with carcinoma of the colon, breast, or ovary seem unlikely to be useful for diagnostic purposes of for monitoring the course of these cancers.

Beta-Globulins↗
PubMed1978

Efficient manometric technic for accurate regional measurement of esophageal body motor activity.

We have developed a single station, manometric recording technic that allows quick and accurate measurement of motor activity occurring in all regions of the esophageal body. The manometric instrumentation features a catheter recording assembly with eight recording orifices spaced at uniform 3 cm. intervals. Each recording lumen is infused with water by a minimally compliant hydraulic-capillary system which achieves accurate recording of peristaltic and nonperistaltic motor activity in the esophageal body at an infusion rate of 0.5 ml./min. Because the recording sites of the manometric assembly span a distance of 21 cm., a distance which approximates the length of the esophageal body in humans, a detailed map of motor activity over the entire length of the esophageal body is achieved by securing the manometric assembly at one suitable portion. Because frequent repositioning of the manometric assembly is eliminated, the method described takes only a few minutes for comprehensive assessment of esophageal body motor activity.

Esophagus↗
PubMed1977

A pneumatically driven pump for constant perfusion manometry.

Syringe pumps are almost universally used for constant perfusion oesophageal manometry, despite important technical limitations. A pneumatically driven perfusion pump has been designed specifically for oesophageal manometry. This pump requires less than one third the flow setting of a syringe pump to achieve a given rate of pressure rise. It is simple to operate and needs infrequent refilling. Nearly two years' practical experience with this pump has confirmed its superiority over the syringe pump for constant perfusion manometry.

Air Pressure↗
PubMed1977

Beta-human chorionic gonadotrophin and carcino-embryonic antigen in the management of ovarian carcinoma.

Measurements of HCG and carcino-embryonic antigen (CEA) were made in 26 patients with ovarian cancer to evaluate these substances as tumour markers; 13-4 per cent of 194 CEA estimations and 14-6 per cent of 144 HCG estimations were abnormal. CEA values were abnormal in 9 out of 26 patients and HCG values in 13 out of 26 patients. The implications of these findings particularly the presence of HCG are discussed.

Adenocarcinoma↗