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Biomedical subjects

L Y Cheung

Publications and source records attributed to L Y Cheung.

At least 91 records · Page 5Linked to original sources
PubMed1978

Topical effects of 16,16 dimethyl prostaglandin E2 on gastric acid secretion and mucosal permeability to hydrogen ions in dogs.

The effects of luminal instillation of 16,16 dimethyl PGE2 (dmPGE2) on gastric acid secretion and back diffusion of H+ were studied in anaesthetised dogs which were prepared with a segment of the greater curvature of the stomach mounted in a double lumen chamber. This model permitted simultaneous evaluation of two segments of mucosa, one control and the other test, supplied by the same vascular pedicle. Imfusion of histamine (1.0 microgram/kg/min, intravenously) stimulated brisk acid secretion in both chambers. Topical application of 25 microgram dmPGE2 in 20 ml 0.3 M HC1 to the test chamber for 30 minutes prevented acid secretion from the test mucosa during a second histamine infusion. Since the control chamber showed no evidence of inhibition this indicates that dmPGE2 acted directly on the secretory cells, rather than after absorption from the bloodstream. This observation, however, does not exclude a possible local effect on mucosal blood flow. Direct exposure of the gastric mucosa to dmPGE2 increased the rate of back diffusion of H+ because of disruption of the permeability barrier, indicated by increased H+ back diffusion, Na+ efflux, and a reduction in potential difference. However, H+ loss was small compared to the reduction in acid output.

Animals↗
PubMed1978

Oxygen consumption during cimetidine and prostaglandin E2 inhibition of acid secretion.

Oxygen consumption was determined during cimetidine and 16,16-dimethyl prostaglandin E2 inhibition of acid secretion in exteriorized segments of the greater curvature of dog stomach. Steady-state acid secretion during histamine infusion correlated well with O2 consumption (r = 0.85, P less than 0.01). Cimetidine and 16,16-dimethyl prostaglandin E2 inhibition of acid secretion produced a reduction of oxygen consumption to resting levels. In contrast, oxygen consumption did not decrease appreciably during thiocyanate inhibition of acid secretion. These observations suggest that the inhibitory action of cimetidine and 16,16-dimethyl prostaglandin E2 precedes, whereas that of thiocyanate is at a point beyond the transfer of energy to the process of acid production.

Animals↗
PubMed1978

Effects of intra-arterial infusion of prostaglandin E1 on gastric secretion and blood flow.

The effect of intra-arterial infusion of Prostaglandin E1 (PGE1) on gastrict total and mucosal blood flow and acid secretion was studied in an exteriorized, chambered preparation of canine fundic stomach. Total gastric blood flow was measured simultaneously by venous outflow and by gamma-labeled microspheres. Mucosal blood flow also was measured by microspheres. Intra-arterial infusion of PGE1 at 1.0 microgram/min completely inhibited histamine-stimulated acid secretion. This inhibition was accompanied by a significant increase in both total (p less than 0.01) and mucosal blood flow (p less than 0.01). The ratio of mucosal to total blood flow remained unchanged during histamine stimulation (78 +/- 4%) and PGE1 inhibition (79 +/- 4%). The results suggest that inhibition of acid secretion can occur in the face of increased blood flow. This observation is contrary to the generally accepted concept that inhibition of acid secretion always is associated with a decrease is mucosal blood flow.

Animals↗
PubMed1977

Detection of occult gallbladder disease by duodenal drainage.

Examination of gallbladder bile in the sediment of duodenal drainage obtained after magnesium sulfate stimulation was used to evaluate the presence or absence of gallbladder disease in thirty-four patients with symptoms suggestive of cholecystitis and normal or equivocal oral cholecystography. Ten patients had positive tests and nine of these had cholecystectomy. All nine had pathologically confirmed cholecystitis and seven of nine had cholelithiasis. Three patients with negative test results had laparotomy and normal gallbladders. The remaining twenty-one patients with negative tests have been followed up to three years, and none have returned with evidence of biliary tract disease. The results of this study suggest that duodenal drainage (Meltzer-Lyon test) is a valuable adjunctive diagnostic study in patients with gallbladder disease symptoms in whom normal or equivocal oral cholecystograms are obtained.

Adult↗
PubMed1976

Stress ulcers: their pathogenesis, diagnosis, and treatment.

Stress ulcers are multiple, superficial erosions which occur mainly in the fundus and body of the stomach. They develop after shock, sepsis, and trauma and are ofter found in patients with peritonitis and other chronic medical illness. Stress ulcers should be differentiated from reactivation of chronic duodenal or gastric ulcers. Cushing's ulcer following head injury, or drug-induced gastritis. Digestive symptoms are usually absent, hemorrhage is the most common manifestation, and perforation and obstruction are rare. The presence of luminal acid and ischemia are necessary for the production of stress ulcer, while disruption of the gastric mucosal barrier by refluxed duodenal content may contribute to the pathogenesis. Endoscopy is the mainstay of the diagnostic procedure, and angiography should be used if endoscopy fails to identify the bleeding lesions. Medical management should include volume replacement, nasogastric aspiration, and the use of antacid. Selective intraarterial infusion of pitressin has shown encouraging preliminary results. Surgical treatment is reserved only for those patients who continue to bleed despite all medical management. The operation of choice is open to question. We prefer vagotomy, pyloroplasty, and oversewing the ulcers as an initial operation. Since the result of all forms of therapy has been poor, it seems resonable to try to prevent ulcer development. The use of vitamin A, hyperalimentation, and growth hormones is still in an experimental stage. Large clinical studies with case control are necessary before recommendations can be made. The use of potent and frequent antacid to buffer the gastric content has shown promising results; however, these observations need to be confirmed in a properly controlled and randomized study.

Gastric Mucosa↗
PubMed1976

Direct effect of endotoxin on the gastric mucosal microcirculation and electrical gradient.

The effects of intra-arterial infusion of E. coli endotoxin at 1.0 mg. per minute on the gastric total and mucosal blood flows, electrical potential difference, and ionic fluxes across the gastric mucosa were studied in an exteriorized, chambered preparation of canine fundic stomach. Gamma-labelled microsphere technique was used in addition to venous drainage and plasma aminopyrine clearance for the measurement of total and mucosal blood flow, respectively. In spite of normal systemic blood pressure throughout the experiment, E. coli endotoxin infusion caused a significant decrease in total gastric blood flow and in the fractional distribution of flow to the mucosae. There was no significant arteriovenous shunting of microspheres. Significant reduction in potential difference and hydrogen-ion back diffusion also was noted after endotoxin infusion, possibly as a consequence of reduced mucosal blood flow. The results indicate that significant gastric mucosal ischemia can occur and may represent a mechanism in the development of gastric erosions in endotoxemia, even in the absence of systemic hypotension.

Animals↗
PubMed1975

Jaundice in patients with acute cholecystitis. Its validity as an indication for common bile duct exploration.

Our study demonstrates that (1) mild to moderate jaundice is frequently seen in patients with acute cholecystitis; (2) severe degrees of jaundice were seen in two patients without the presence of common duct stone or recognizable obstruction of the common bile duct; (3) only one of forty-one patients with acute cholecystitis had common bile duct stone; (4) jaundice does not appear to be a compelling reason for choledochotomy; and (5) less invasive technics such as intravenous and intraoperative cholangiography should suffice to exclude the possibility of common bile duct stone in patients with acute cholecystitis.

Acute Disease↗
PubMed1975

Effect of aspirin, bile salt, and ethanol on canine gastric mucosal blood flow.

The effect of aspirin (20 mM.), sodium taurocholate (40 mM.), and ethanol (24 per cent w/v) on gastric mucosal blood flow was studied in an exteriorized, chambered preparation of canine fundic stomach. Gastric mucosal blood flow was measured by gamma-labeled microspheres and plasma aminopyrine clearance. All three test solutions caused a significant increase in microsphere-measured mucosal blood flow. The degree of increase in gastric mucosal blood flow was proportional to the severity of gross mucosal injury, being greatest with bile salt and least with ethanol. Plasma aminopyrine clearance determined only a small fraction of mucosal flow measured by microspheres following injury, particularly in sodium taurocholate and ethanol experiments, where the net hydrogen ion back diffusion was greatest. The results suggest that increased gastric mucosal blood flow may be a secondary defensive response to the damage caused by these irritants and that the plasma aminopyrine clearance is unreliable in quantitating mucosal blood flow changes in the presence of mucosal injury.

Aminopyrine↗