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Biomedical subjects

F G Moody

Publications and source records attributed to F G Moody.

At least 19 recordsLinked to original sources
PubMed1992

Anatomy of the bilioduodenal junction of the opossum.

Prevention of reflux is a major function of the terminal biliary duct system at its junction with the duodenum. We examined this area via scanning electron microscopy and light microscopy to explore anatomic features that might play such a role in the Virginia opossum, a species with a highly developed sphincter of Oddi (SO). The terminal apparatus, most of which consists of a dilated extramural ampulla, has a lumen with abundant folds. Mucus is produced by the lining epithelium and by a plethora of glands. Three muscle layers constitute the SO: an inner longitudinal, an outer circular, and a less consistent outermost longitudinal. The terminal apparatus forms an acute angle and narrows as it enters the duodenum; at this point, the SO becomes continuous with the muscularis externa of the intestine. Four anatomical features with potential antireflux properties may be identified: mucus production, luminal folds, and the narrow opening and oblique course of the intramural duct.

Animals↗
PubMed1992

Influence of shock on development of infection during acute pancreatitis in the rat.

This study tested the hypothesis that hypovolemic shock elicits or promotes the development of infection during acute pancreatitis. Pancreatitis was induced in rats by ligation of the common biliopancreatic duct; nonlaparotomized animals served as controls. After 24 hr, the animals were subjected to either sham-shock (instrumented only) or to shock by withdrawal of blood through a femoral artery line by maintaining the mean arterial blood pressure at 30 mm Hg for 1 or 2 hr. After completion of the shock period, the shed blood was returned to the animal. All animals were sacrificed 24 hr later and specimens obtained from portal and systemic blood, liver, spleen, pancreas, and mesenteric lymph nodes for bacteriologic culture using standard techniques. The pancreas was also analyzed by morphometric techniques. The histologic changes of pancreatitis induced by biliopancreatic obstruction were characterized by marked edema with accompanying mild inflammation, hemorrhage, and necrosis. Concomitant with these morphologic findings was an associated translocation of enteric organisms to the mesenteric lymph nodes without spread to distant organs. Shock by itself induced only a mild edema in the pancreas and did not cause bacterial translocation. Furthermore, shock failed to aggravate the morphologic alterations of acute pancreatitis and did not promote bacterial spread to mesenteric nodes over that observed with pancreatitis alone. Thus, we conclude that periods of severe shock lasting up to 2 hr do not play a major role in the pathogenesis of infection in our model of pancreatitis.

Acute Disease↗
PubMed1992

Bacterial flora of the gastrointestinal tract of opossums.

The bacterial flora of the stomach, small intestine, cecum and bile from 20 healthy opossums (Didelphis virginiana) captured from the wild was studied. Results showed that their gastrointestinal flora was similar to that found in other small mammals but, in addition, opossums are heavily colonized by Salmonella spp., which might adversely affect their adequacy as laboratory animals for some experimental protocols.

Animals↗
PubMed1991

Effect of bile diversion and sphincterotomy on gallbladder muscle contractility and gallstone formation.

Feeding prairie dogs a diet rich in cholesterol induces gallstone formation that is preceded by a sustained decrease in gallbladder smooth muscle contractility. Sphincterotomy is known to prevent gallstone formation in cholesterol-fed prairie dogs. Experiments were designed to determine whether the effect of sphincterotomy is a consequence of hepatic bile diversion, and whether bile diversion prevents the altered contractility. Following sham operation, surgical biliary enteric bypass, or sphincterotomy, prairie dogs were fed a high-cholesterol or a regular diet. Gallbladder muscle contractility and the presence of crystals and stones were determined. In sham-operated animals, the cholesterol diet induced a decrease in gallbladder muscle contractility and caused the formation of cholesterol gallstones. In animals with bile diversion and sphincterotomy, the effects of cholesterol feeding were reduced or prevented. Thus, these procedures may prevent stone formation by preventing a reduction in gallbladder contractility. Contractility was depressed in animals with bile diversion fed a regular diet, compared with animals with a sham operation fed a regular diet. The mechanism for this depression may differ from that induced by the cholesterol diet. Diversion, and perhaps sphincterotomy, impairs gallbladder filling. Thus, gallbladder muscle is not stretched and does not contract against a load. This could result in a "disuse atrophy." If the results from our study apply to humans, sphincterotomy may reduce stone formation by preventing the effects of lithogenic bile on gallbladder muscle contractility and by enhancing the ability of the muscle to empty the lithogenic bile.

Animals↗
PubMed1991

Transduodenal sphincteroplasty with transampullary septectomy for stenosing papillitis.

The papilla of Vater and its sphincter of Oddi, lying at the confluence of the bile and pancreatic ducts in man, have long been suspected as a source of upper abdominal pain. Enlarging the opening of the transpapillary segment of the bile and major pancreatic ducts by using a transduodenal sphincteroplasty with transampullary septectomy resulted in death in a patient with a peripapillary diverticulum and pancreas divisum. Eight-six patients followed for 1 to 10 years experienced a 75% success rate. Thirty-six patients had a marked stenosis of their duct of Wirsung, suggesting that their pain was primarily from the pancreas. The remainder had either a generalized narrowing (40 patients) or a normal (7 patients) papilla. Pain was not satisfactorily resolved in patients with an associated pancreas divisum, chronic pancreatitis, and recurrent episodes of acute pancreatitis with alcoholism.

Abdominal Pain↗
PubMed1991

Stress erosive gastritis.

Bleeding from stress erosive gastritis continues to be a potential problem in critically ill and injured patients, but fortunately its incidence has decreased dramatically over the last decade. The explanation for this circumstance is probably multifactorial, but clearly relates to our increased knowledge of its pathophysiology. This understanding has led to the routine use of measures to reduce intragastric acidity (luminal acid being a prerequisite for stress ulcer to occur), coupled with improved techniques for the treatment of shock and the accompanying gastric mucosal hypoperfusion (another prerequisite for the formation of stress ulcers). A number of measures have been used to lower intragastric acidity with H2 receptor blockers emerging as the agents of choice to accomplish this goal. In the unlikely event that bleeding occurs despite these prophylactic measures, aggressive medical management will result in cessation of hemorrhage in over 80% of patients. In those few individuals requiring surgery to control bleeding, no operation has emerged as the recognized procedure of choice. Thus, we believe that a conservative operative approach is indicated in this setting and recommend vagotomy and pyloroplasty with oversewing of the bleeding erosions as appropriate therapy for most patients requiring surgical intervention.

Gastritis↗
PubMed1991

The role of the gut in the development of sepsis in acute pancreatitis.

The pathogenesis of sepsis in acute pancreatitis is unknown. Since the intestinal tract has recently been identified as a possible source for sepsis in other conditions, we explored whether the gut may serve as a reservoir for bacteria causing systemic and pancreatic infection in acute pancreatitis. Bacterial translocation, alterations of intestinal microflora, and intestinal motility, as reflected by gut propulsion, were studied in a rat pancreatitis model. Acute pancreatitis was induced by biliopancreatic obstruction (AP); sham manipulated animals served as controls (sham). Bacteriologic cultures were obtained from various segments of the intestinal tract and from blood, liver, spleen, pancreas, and mesenteric lymph nodes 48 and 96 hr after induction of AP or sham. Bacteria were recovered from mesenteric lymph nodes of all 12 animals with AP, but only from 3/14 sham animals (P less than 0.05). Spread to distant organ sites occurred in 4 of 12 animals with AP compared to none of the sham animals (P less than 0.05). A disruption of the intestinal microflora was found in the cecum, where the gram-negative bacterial count (log/g) was significantly higher during AP when compared with sham controls: 10.62 +/- 1.04 vs 8.05 +/- 1.45 at 48 hr and 7.92 +/- 0.62 vs 6.79 +/- 0.87 at 96 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Use of a modified Ussing chamber to monitor intestinal epithelial and smooth muscle functions.

A technique that allows the simultaneous monitoring of epithelial and smooth muscle function was developed and used to study rat small intestine in vitro. A Ussing chamber was modified so that a strain gauge force transducer could be sewn to the serosal surface of an intestinal segment clamped in the chamber. The apparatus was used to monitor short-circuit current, potential difference, and resistance across the segment, and contractions of the longitudinal layer of the muscularis externa. Both spontaneous activity and responses to the application of carbachol were recorded. Carbachol applied to the serosal side induced dose-dependent increases in both short-circuit current and contractile force. The median effective doses of the two responses differed, with contractions being more sensitive to the drug. Carbachol applied to the mucosal side induced no changes in either epithelial or contractile activities. The ability of the serosal strain gauge transducer to monitor contractions faithfully was tested in an organ bath in which the gut segment was attached to an external force-displacement transducer. There was a close correlation between the dose-dependent increase in force in response to carbachol measured by the serosal transducer and that measured by the force-displacement transducer (r = 0.988). Thus our technique can be used to study simultaneously epithelial and smooth muscle functions of the intestine.

Animals↗
PubMed1991

Salmonella infection of the biliary and intestinal tract of wild opossums.

Bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (Didelphis virginiana) obtained directly from the wild for use as research animals. The overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. Salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. Among these six animals, translocation of Salmonella to regional lymph nodes was observed in five animals, bacteremia in three animals, and spread to liver or spleen in five animals, respectively. The biliary tract was sterile in 12 opossums (67%). In these 12 animals, bacteria were isolated from the celiac and superior mesenteric lymph nodes of five animals, the blood of two animals, and the liver and spleen of one animal, respectively. Bacteriologic cultures were obtained from the intestinal tract and from extraintestinal sites in nine opossums. Salmonella were found in the small bowel of two animals, both of which had biliary salmonellosis. In addition, Salmonella was isolated from extraintestinal organs of three animals with negative cultures from the gut. All isolates identified were: S. enterica subsp houtenae. These data establish the biliary tract of wild opossums as a reservoir for Salmonella enterica subsp houtenae which may be particularly important when opossums are used in research laboratories.

Animals↗
PubMed1990

Choledochoduodenal flow: effect of the sphincter of Oddi in opossums and cats.

The aim of this study was to test in vivo (a) whether the sphincter of Oddi acts as a resistor or also as a pump, (b) the effect of an IV infusion of cholecystokinin (CCK) on choledochoduodenal flow, and (c) the ability of the choledochoduodenal junction to prevent duodenobiliary reflux in two animal species, opossums (n = 11) and cats (n = 8). Opossums were implanted with bipolar electrodes on the sphincter of Oddi and the adjacent duodenum. Cats were not. Experiments were performed in vivo using a propulsion evaluation system to test whether the Sphincter of Oddi was able to pump fluid from the bile duct to the duodenum against pressure gradients. In 5 opossums and 4 cats, choledochoduodenal flow was evaluated during the IV infusion of CCK (20 ng.kg-1.min-1). The opossum sphincter of Oddi moved fluid against duodenal pressure gradients of 6-45 cm H2O. The spike-burst frequency (6.4 +/- 1.7 min-1) was maximal at peak bile duct pressures and decreased as bile duct pressure decreased (4.9 +/- 1.6 min-1; P less than 0.001). Pressure pulses in the bile duct were observed at a frequency that correlated with sphincter of Oddi spike-burst frequency (r = 0.84; P less than 0.001). In cats, choledochoduodenal flow occurred only along a hydrostatic gradient; the sphincter of Oddi never acted as a pump but only as a resistor. Infusion of CCk significantly increased the frequency of sphincter of Oddi contractions in opossums, but the transfer of fluid from bile duct to duodenum was significantly reduced. In cats, the rate of fluid flow from the bile duct to the duodenum during CCK infusion did not differ from control values. Reflux of duodenal fluid into the biliary tree was never observed, even at duodenal pressures as high as 100 cm H2O. In conclusion, in vivo, the sphincter of Oddi is able to pump fluid from the bile duct to the duodenum against a pressure gradient in opossums, but, in cats, choledochoduodenal flow requires a bilioduodenal pressure gradient. The increase in sphincter of Oddi contraction frequency induced by CCK in opossums resulted in a decrease in active transsphincteric flow. Duodenobiliary reflux could not be elicited in opossums and cats under the conditions of these experiments.

Animals↗
PubMed1990

Actin and myosin isoforms in gallbladder smooth muscle following cholesterol feeding in prairie dogs.

Gallbladder smooth muscle contractility decreases after high-cholesterol feeding in prairie dogs. This decrease is not associated with alterations in the total amounts of the contractile proteins actin and myosin. The present study was designed to determine if cholesterol feeding results in alterations in the isoforms of actin and/or myosin heavy chain in gallbladder smooth muscle. Control prairie dogs were fed a trace-cholesterol diet and test animals were fed a high (1.2%)-cholesterol diet for 8 days. Although the proportion of beta-actin was unchanged, the proportion of alpha-actin in the gallbladder was less in the animals fed the high-cholesterol diet (32.6% +/- 1.5% in the control animals and 24.6% +/- 0.4% in the diet animals). On the other hand, the proportion of gamma-actin was significantly greater in the cholesterol-fed animals. There were no significant differences in the proportions of the myosin heavy-chain isoforms between the two groups. Also, there was no change in the volume fraction of smooth muscle in the gallbladders from the two groups. Thus, cholesterol feeding induces a shift in actin isoforms at the same time that there is a decrease in contractility. Whether the altered pattern of actin isoforms is related to the functional changes remains to be determined.

Actins↗
PubMed1990

Stenosis of the sphincter of Oddi.

"Stenosing papillitis" is a descriptive term for an anatomic deformity of the papilla of Vater that is characterized by narrowing of the lower end of the bile duct and the proximal end of the duct of Wirsung. The defect is secondary to inflammation and fibrosis from the chronic passage of gallstones, episodes of acute pancreatitis, chronic pancreatitis, sclerosing cholangitis, peptic ulcer disease, and cholesterolosis. Patients with papillary stenosis from gallstones may present with episodes of severe upper-abdominal pain several years after cholecystectomy. The pain is often incapacitating, and patients are often addicted to narcotic analgesics. The work-up includes abdominal ultrasonography and CT scanning and endoscopic retrograde cholangiopancreatography even though the findings usually are normal. Liver and pancreatic enzymes are not frequently elevated with the painful episodes. Transendoscopic manometry may reveal elevated pressures within the papillary portion of the distal bile duct. Some patients are relieved of their pain by transduodenal sphincteroplasty and transampullary septectomy, thereby ablating the sphincter of Oddi around the bile and pancreatic ducts and enlarging their openings.

Cholestasis, Extrahepatic↗
PubMed1990

Biliary and gut function following shock.

The aim of this study was to characterize the alterations in gallbladder and intestinal function after hemorrhagic shock and blood reperfusion in opossums. Animals were subjected to a shock of 30 mm Hg of arterial blood pressure for 60 minutes and resuscitated with blood reinfusion. Gallbladder epithelial ion transport, gallbladder motility in vitro and in vivo, gastrointestinal motility, and flora of the stomach and small bowel were studied 2 and 24 hours after shock. Changes at 2 hours included decreased gallbladder contractility in vitro and decreased emptying in vivo, loss of coordination with intestinal motor activity, decrease in frequency of intestinal electrical slow waves, and reduced duration of the intestinal migrating motor complex cycle. By 24 hours, gallbladder epithelial permeability was increased and in vitro contractility remained reduced but the in vivo functions showed partial recovery. Gastrointestinal flora was not affected by these changes. These data demonstrate that hemorrhagic shock and reperfusion affect digestive motility. The early timing of the alterations observed and the partial recovery 24 hours post shock suggest an ischemia-hypoxia mechanism of injury.

Animals↗
PubMed1990

The propulsive behavior of the opossum sphincter of Oddi.

This study investigates whether the phasic contractions of the opossum sphincter of Oddi (SO) delay bile flow by acting as a resistor or facilitate bile flow by acting as a pump. The common bile duct (CBD) and an adjacent segment of duodenum from eight opossums were studied in a propulsion evaluation system in vitro. This system required the production of hydrostatic work by the SO to transfer fluid from the CBD to the duodenum when the pressure in the duodenum was equal or greater than the pressure in the CBD. Fluid movement from the CBD to duodenum and duodenum to CBD was studied at pressure gradients up to 50 cmH2O before and after sodium nitroprusside (10(-7) M) inhibition of smooth muscle contractile activity. All preparations propelled fluid from the CBD to the duodenum against a pressure gradient ranging from 10 to 50 cmH2O. The SO emptied the CBD in a monoexponential fashion, with a time constant of 1.52 +/- 0.7 min, until CBD pressure was reduced to 8.5 +/- 3.2 cmH2O, when propulsion ceased. Superimposed on the CBD pressure waveform were pressure pulses of 1-2 cmH2O in amplitude that resulted from the contractions of the SO. CBD pressure was higher at the start than at the end of a periodic pressure pulse, whereas CBD pressure was stable between pulses. The frequency of the pressure pulses was greatest at the maximal CBD pressure (9.4/min) and decreased significantly when the basal pressure was reached (1.5/min, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ampulla of Vater↗
PubMed1990

Gallbladder and gastrointestinal motility after hemorrhagic shock.

The alterations in fasting gallbladder and gastrointestinal motility during hemorrhagic shock were investigated. Eight opossums implanted with a gallbladder cannula, gastrointestinal bipolar electrodes, and a carotid catheter were subjected to hemorrhagic shock of 30 mm Hg for 60 minutes by the removal of arterial blood. Shed blood was reinfused after the shock period. Fasting gallbladder volume and gastrointestinal electrical activity were studied before, immediately after, and 24 hours after hemorrhagic shock. Control measurements demonstrated a slow-wave frequency maximal in the duodenum (18.1 +/- 1.1 waves/min), with a plateau in the proximal third of the small bowel, decreasing thereafter. The migrating motor complex (MMC) had a duration of 118 +/- 28 minutes. The average volume of the gallbladder before shock was 5.4 +/- 1.5 ml. Gallbladder volume fluctuated with the MMC, being maximal during phase I and minimal in phase III. The volume of blood removed to reduce mean arterial pressure to 30 mm Hg was 45 +/- 5 ml/kg. Immediately after the shock and blood reinfusion, slow-wave frequency decreased by 40% in the antrum and 25% in the small bowel. The MMC was of shorter duration (91 +/- 22 minutes; p less than 0.05), and gallbladder volume increased to 7.0 +/- 1.7 ml (p less than 0.05). Fluctuations in gallbladder volume during the MMC were absent. Twenty-four hours after shock, slow-wave frequency, MMC, and gallbladder volume had returned to normal and were not different from control measurements. Ischemic damage to the gastrointestinal tract is postulated as the cause of gallbladder dysfunction and altered intestinal motility after hemorrhagic shock.

Animals↗
PubMed1989

Morphology of the prairie dog gallbladder: normal characteristics and changes during early lithogenesis.

Studies were undertaken to describe the normal structure of the prairie dog gallbladder and adjacent cystic duct, and then to determine sequential changes that occurred as abnormalities in bile composition developed during high cholesterol feeding. Control animals were fed a diet with trace cholesterol, while experimental animals were fed a diet enriched with 1.2% cholesterol for 1, 2, 3, or 4 weeks. Light microscopy and scanning and transmission electron microscopy were used to characterize morphologic changes at each time interval. Biliary lipid composition was altered in all experimental groups, evidenced by significant decreases in bile-acid-to-cholesterol ratios. Cholesterol crystals appeared in experimental bile at 1 and 2 weeks, while stones formed at 3 and 4 weeks. The cystic duct and neck of the gallbladder occasionally displayed goblet cells. Little mucus was demonstrable in principal cells of the gallbladder, but much more in those lining the cystic duct. After 2 weeks of lithogenic diet, there was an increase in mucus content and secretion from all areas, as well as an influx of polymorphonuclear and mononuclear leukocytes. Accumulation of plasma cells in the lamina propria was an especially prominent feature of experimental tissues. These results suggest that 1) there is regional heterogeneity in the mucus content of the gallbladder and cystic duct of the prairie dog, and 2) both regions respond to lithogenesis with mucus hypersecretion and acute and chronic inflammatory changes prior to the appearance of cholesterol gallstones.

Animals↗
PubMed1989

Lithotripsy for bile duct stones.

Fragmentation of bile duct stones by mechanical, electrohydraulic, and laser intraluminal lithotripsy has greatly facilitated the ability to remove stones that are otherwise difficult to remove by standard manipulative techniques. Even these approaches fail when stones lack access or are impacted within the biliary tree. Extracorporeal shock-wave lithotripsy (ESWL) was evaluated in the United States in a multicenter trial with 56 patients. Stone fragmentation occurred in 91 percent of patients and duct clearance in 79 percent. Adjunctive procedures were used in 54 percent. Two ESWL treatments were required for fragmentation in 28 percent. Complications were mild and relatively infrequent. Hemobilia (8 percent), gross hematuria (6 percent), and biliary sepsis (4 percent) occurred less frequently than expected. There were no deaths during the 1 to 31 days of hospitalization (mean 9 days). We conclude that ESWL is a safe and effective adjunct to the treatment of difficult-to-remove bile duct stones under the conditions observed in this trial.

Bile Duct Diseases↗