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Biomedical subjects

Y F Li

Publications and source records attributed to Y F Li.

At least 145 records · Page 8Linked to original sources
PubMed1986

Endotoxemia after relief of biliary obstruction by internal and external drainage in rats.

Systemic and portal endotoxemia were studied in rats with biliary obstruction and after relief of the obstruction by internal and external drainage. Endotoxemia was increased after bile duct ligation (p less than 0.001) compared with control values. The incidence of systemic and portal endotoxemia was significantly reduced after internal drainage (p less than 0.001). A significantly higher incidence of portal (86 percent) and systemic (57 percent) endotoxemia, however, was found after external drainage. The persistence of endotoxemia after external drainage, when serum bilirubin levels returned to normal units, indicates that bile flow is important in controlling endotoxemia during preoperative biliary drainage. These results suggest that the systemic endotoxemia observed after relief of obstruction by external drainage may contribute to the increased mortality, as found in previous rat studies. This observation may contribute to an understanding of why patients with preoperative external drainage of biliary obstruction have a higher incidence of septic complications.

Animals↗
PubMed1986

Gastrointestinal motility following small bowel obstruction in the opossum.

The motility of the gastrointestinal tract of six opossums with total and four with partial small bowel obstruction was evaluated. Following the establishment of small bowel obstruction, the migrating myoelectric complex was substituted by a new pattern which was characterized by periods of intense spike activity interspersed with quiescent periods. In the experiments with total intestinal obstruction, the frequency and duration of the periods of intense spike activity were related to the recording site and the time after establishment of intestinal obstruction. The frequency of spike bursts in the ileum proximal and distal to the obstruction was the greatest in the first 2 days after the establishment of the obstruction, while in the antrum and proximal small bowel, the frequency of bursts of spike potentials increased gradually from the first to the fourth postobstruction day (P less than 0.01). However, there was no change in the frequency, duration, and localization of periods of intense spike activity during the 5 days following the establishment of partial intestinal obstruction. We concluded that following intestinal obstruction, the migrating myoelectric complex is substituted by a myoelectric pattern that is characterized by periods of intense spike activity interspersed with quiescent periods. In the animals with total intestinal obstruction, the periods of increased motility are initially more frequent in the bowel proximal and distal to the obstruction and afterwards in the stomach and upper small bowel.

Animals↗
PubMed1986

Serotonin increases the velocity of propagation and frequency of the migrating myoelectric complexes.

The effect of serotonin on the myoelectric activity of the gastrointestinal tract was evaluated in seven opossums. Continuous intravenous administration of serotonin reduced the cycle duration of the migrating myoelectric complex and increased the velocity of propagation of the phase III. These changes were dose-dependent and were observed only with high doses of serotonin of 0.1 mg kg-1 h-1 or more. Infusion of 0.01 mg kd-1 h-1 had no effect on the motility of the gastrointestinal tract. The motility changes occurred in all segments of the gastrointestinal tract studied and were characterized by a continuous and organized increase in the velocity of propagation of the activity front (phase III) of the migrating myoelectric complex from the antrum to the terminal ileum. The cycle duration of the two migrating myoelectric complexes following administration of methysergide at 1.0 mg kg-1 was similar to the control migrating myoelectric complexes. We concluded that continuous infusion of serotonin in the opossum increases the velocity of propagation of the phase III of the migrating myoelectric complex from the antrum to the terminal ileum.

Animals↗
PubMed1986

Effect of 16,16-dimethyl prostaglandin E2 on the myoelectric activity of the gastrointestinal tract of the opossum.

Myoelectric recordings of the opossum gastrointestinal tract were performed during continuous infusion of 16,16-dimethyl prostaglandin E2 at 0.1, 1, 2 and 5 micrograms/kg X h. Continuous administration of prostaglandin caused a dose-dependent reduction of the duration of the migrating myoelectric complex cycle and an increase in the velocity of phase III migration from the duodenum to the terminal ileum. The reduction of the migrating myoelectric complex cycle was due to a shortening of the duration of both phase I and II. Bolus administration of 16,16-dimethyl prostaglandin E2 caused intense spike activity for 2-4 min in all recording sites simultaneously. Administration of indomethacin did not change the myoelectric activity of the gastrointestinal tract. Infusion of prostaglandin E2 caused diarrhoea in eight of forty experiments. These changes in gastrointestinal motility may be important contributory factors in the pathogenesis of prostaglandin-induced diarrhoea.

16,16-Dimethylprostaglandin E2↗
PubMed1986

Influence of autonomic drugs on the motility of the sphincter of Oddi in the opossum.

We have evaluated the effect of various autonomic drugs on the electromyographic activity of the sphincter of Oddi and the small intestine of seven opossums. Hexamethonium bromide and atropine sulfate abolished and bethanechol increased the frequency of spike bursts in the sphincter of Oddi and duodenum. Phenylephrine and epinephrine increased the number of spike bursts in the sphincter of Oddi after a short period of stimulation. No spike potentials were seen in the duodenum after infusion of norepinephrine. Clonidine and dobutamine decreased spike burst activity in the sphincter of Oddi and duodenum. Terbutaline also decreased the frequency of spike bursts in the sphincter of Oddi but did not change the number in the duodenum. Prior infusion of antagonists blocked partially or totally the effect of all respective agonists except for yohimbine, which did not inhibit the effect of clonidine. These findings suggest that the sphincter of Oddi may have cholinergic, alpha 1, alpha 1, beta 1 and beta 2-adrenergic receptors. Cholinergic agonists stimulate and alpha 2, beta 1 and beta 2-adrenergic agonists inhibit the motility of the sphincter of Oddi and the small intestine. Alpha-adrenergic agonists stimulate the motility of the sphincter of Oddi and inhibit the motility of the small intestine.

Ampulla of Vater↗
PubMed1986

Gallbladder contractility and mucus secretion after cholesterol feeding in the prairie dog.

The purpose of our study was to evaluate changes in gallbladder contractility and mucus secretion in vitro during the early stages of gallstone formation in prairie dogs. Thirty-two animals were divided into five groups. Control animals were fed a trace cholesterol diet. Experimental animals were fed a high-cholesterol diet for 3, 6, 8, and 14 days, respectively. Muscle stress was measured in response to cholecystokinin octapeptide in each of the groups. The maximal stresses in the 8-day diet (68 +/- 7 gm/cm2) (mean +/- SEM) and 14-day diet animals (83 +/- 7 gm/cm2) were found to be significantly lower than those of the control animals (137 +/- 12 gm/cm2). The stress in 3-day diet animals was significantly greater (224 +/- 23 gm/cm2). A significant increase in mucus secretion was observed only in 14-day diet animals (11.0 +/- 0.5 X 10(6) dpm/gm dry wt) compared with the control animals (6.4 +/- 1.0 X 10(6) dpm/gm). The decrease in contractility may be the initial event in cholesterol stone formation, and the prolonged exposure of the gallbladder epithelium to crystals may stimulate the release of mucus into the bile.

Animals↗
PubMed1986

Estimation of hepatic blood flow by hydrogen gas clearance.

The hydrogen gas clearance technique was evaluated to estimate regional hepatic blood flow. Initially, the H2 gas method was compared to the indocyanine green clearance in mini pigs. The blood flow measured by the H2 gas method (0.49 +/- 0.03 ml/min/gm) was only 39% of the calculated blood flow by the indocyanine green method (1.26 +/- 0.14 ml/min/gm). The blood flow determined by H2 gas decreased to 0.06 +/- 0.04 ml/min/gm after ligation of the hepatic artery. No difference in blood flow was found by simultaneous measurements on the left (0.89 +/- 0.1 ml/min/gm) and right (0.96 +/- 0.13 ml/min/gm) liver lobes in rats. After ligation of the left hepatic artery in the rats, a delayed response to H2 application was present and the determined blood flow (0.14 +/- 0.02 ml/min/gm) was significantly reduced (p less than 0.001) compared with the right liver lobe H2 determined blood flow as a control. No current was generated after ligation of the left hepatic artery and the portal vein indicating that there was no blood flow measured by the gas H2 method. The results indicate that the H2 gas clearance technique may be a method that assesses hepatic arterial liver perfusion rather than estimates total hepatic blood flow. The safety and simplicity of the H2 gas clearance technique may make it suitable for clinical application in serial measurement of hepatic arterial blood flow in man.

Animals↗
PubMed1985

Effects of gastrointestinal hormones on Oddi's sphincter and duodenal myoelectric activity and pancreatobiliary pressure. Studies in the opossum.

Myoelectric activity of Oddi's sphincter and duodenum was correlated with common duct and pancreatic duct pressures in conscious opossums after infusion of the following substances: cholecystokinin, pentagastrin, glucagon, secretin, and acetylcholine. Cholecystokinin and pentagastrin increased and glucagon and secretin decreased the frequency of spike potentials in Oddi's sphincter and the duodenum. Acetylcholine was associated with the largest increase in spike potentials in both Oddi's sphincter and the duodenum. Although there was variation in the number of pressure elevations related to Oddi's sphincter spike potentials, the baseline pressure remained constant during administration of the hormones. Acetylcholine infusion increased the biliary and pancreatic pressures to 29 and 31 mm Hg, respectively. We conclude that gastrointestinal hormones may have an important role in regulating the excretion of bile and pancreatic juice into the duodenum.

Acetylcholine↗
PubMed1985

Experimental evaluation of gastric banding for treatment of morbid obesity in pigs.

The effectiveness and complications of gastric banding were evaluated in 15 miniature pigs. A Gore-tex or Dacron graft was employed to encircle the stomach. The animals were divided into five groups, three pigs in each group. Group 1 had a 13 mm pouch stoma with a Gore-tex band, Group 2 had a 16 mm pouch stoma with a Gore-tex band, Group 3 had a 13 mm pouch stoma with a Dacron band, Group 4 had a 16 mm pouch stoma with a Dacron band, and Group 5 had a sham operation. The weight variation in the control group was significantly higher than that in the other groups at the ninth postoperative week (p less than 0.05). There was no significant difference among Groups 1, 2, 3, and 4. The gastric band had migrated distally in seven pigs. It was located in the body of the stomach in four animals and in the pylorus in three. These three pigs died from stenosis of the pylorus. The band had eroded and penetrated all stomach layers in three other animals. There was no difference in the incidence of postoperative complications between the Gore-tex and Dacron band groups. The use of this simple operation in the treatment of the morbidly obese patient should be applied with caution.

Animals↗