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Biomedical subjects

R F Werkman

Publications and source records attributed to R F Werkman.

7 recordsLinked to original sources
PubMed1998

Biliary, pancreatic, and sphincter of Oddi electrical and mechanical signals recorded during ERCP.

Measurements of biliary tract motility have focused on radiologic and pressure measurements to quantify biliary motility rather than measurements of electrical activity of the biliary tract. We previously reported the recording of biliary electrical signals during ERCP and now report on the continued development and validation of a system to measure biliary tract electrical activity as well as biliary mechanical activity. In 26 patients presenting with a variety of clinical indications, we recorded measurements of electrical activity from the common bile duct sphincter (16 patients), pancreatic duct sphincter (eight patients), and/or sphincter of Oddi (eight patients). Electrical recordings were performed with a specially modified ERCP catheter, using two circular electrodes as well as a custom catheter that measured both electrical and mechanical activity. Electrical activity of the biliary tract was successfully recorded in 25 of 26 patients (96%), including the common bile duct sphincter (16 patients, 62%), pancreatic duct sphincter (eight patients, 31%) and sphincter of Oddi (eight patients, 31%). Along with the electrical recordings, common bile duct sphincter mechanical activity was recorded in 12 patients (67%), pancreatic duct sphincter mechanical activity in six patients (33%), and sphincter of Oddi mechanical activity in six patients (33%). Frequency analysis of electrical signals revealed a mean frequency (cycles/min) of 4.7 +/- 0.5 in the common bile duct sphincter, 4.1 +/- 0.6 in the pancreatic duct sphincter, and 4.9 +/- 0.7 in the sphincter of Oddi. Phasic mechanical frequency in cycles per minute was recorded at a frequency of 4.8 +/- 0.5 in common bile duct sphincter, 4.0 +/- 0.6 in pancreatic duct sphincter, and 5.3 +/- 0.9 in sphincter of Oddi. Tonic pressure (averaged 12.1 +/- 1.5 mm Hg) in common bile duct sphincter, 12.4 +/- 1.4 mm Hg in pancreatic duct sphincter, and 15.0 +/- 5.1 mm Hg in sphincter of Oddi. Analysis of wave form propagations (noted as percentage antegrade, retrograde, or indeterminant) revealed 50% antegrade, 23% retrograde, and 27% indeterminant). One patient was recorded on two occasions via ERCP; the same patient had an intraoperative recording. All three recordings showed similarities. We conclude that measurements of biliary, pancreatic, and sphincter of Oddi electrical and mechanical activity are feasible and can be done as part of ERCP. There was good correlation between biliary tract electrical and mechanical events and different wave form characteristics were noted for different parts of the biliary tree. Further studies are warranted to evaluate the potential usefulness of measurement of biliary tract electrical activity, and to confirm its correlation with mechanical events in the pancreato-biliary tree.

Adult↗
PubMed1998

A fistula from the portal vein to the bile duct: an unusual complication of transjugular intrahepatic portosystemic shunt.

We describe a case of a portal vein bile duct fistula as a complication of transjugular intrahepatic portosystemic shunt (TIPS) placement. The patient's course was complicated by endocarditis, hemobilia, recurrent episodes of fever, and bacteremia, followed by liver transplant. The findings of fever, bacteremia (especially with Gram-negative organisms), and a decreased hematocrit after shunt placement should raise the suspicion of an infected shunt with a possible fistula.

Bacteremia↗
PubMed1996

Gastrointestinal motility disorders.

A careful history can localize gastrointestinal motility disorders and suggest appropriate diagnostic tests. Dysphagia, odynophagia, heartburn and reflux have esophageal origins. The same symptoms occur in achalasia, a classic motor disorder of the lower esophageal sphincter, which can be diagnosed by barium swallow, endoscopy and esophageal motility studies. Nausea, vomiting, anorexia, bloating and abdominal pain are symptoms of motor disorders of the stomach and small intestine. When these symptoms are accompanied by unexplained right upper quadrant pain, elevated liver enzyme levels and unexplained recurrent pancreatitis, the diagnosis of impaired biliary motility is suggested. Colorectal motility disorders may present as abdominal pain, diarrhea, constipation and/or fecal incontinence. If symptoms do not resolve with dietary changes and appropriate medications and the anatomy is normal on lower gastrointestinal studies, colorectal motility studies may be indicated.

Biliary Dyskinesia↗
PubMed1986

Biochemical changes in the intestine associated with anoxia and reoxygenation: in vivo and in vitro studies.

In ischemia/reperfusion injury, it is hypothesized that superoxide is responsible for the component of injury due to reperfusion. The superoxide is hypothesized to result from the aerobic oxidation of purines produced by the ischemia-mediated breakdown of high-energy phosphates. This oxidation is catalyzed by xanthine oxidase proposed to be rapidly formed as a result of ischemia-mediated protease conversion from xanthine dehydrogenase. In vivo experiments with the intestine of either rats or guinea pigs were unable to confirm the rapid conversion of xanthine dehydrogenase to xanthine oxidase as a result of ischemia. In vitro experiments with isolated guinea pig enterocytes did show a significant increase in xanthine oxidase activity after these cells were first placed in an anaerobic environment for 60 min and then reoxygenated; however, the magnitude of the increase is such that the biological importance of this finding remains uncertain. Using a variety of techniques, including spin trapping, hydroxylamine oxidation, and vanadate NADPH oxidation, we explored the possibility that superoxide was produced as a result of anoxia followed by reoxygenation in the in vitro enterocyte system. From these experiments, we determined that superoxide is generated as a result of anoxia/reoxygenation. However, from xanthine oxidase inhibition experiments using pterinaldehyde, only a small percentage of the total superoxide produced comes from the action of this enzyme on purines.

Animals↗