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Biomedical subjects

R E Condon

Publications and source records attributed to R E Condon.

At least 19 recordsLinked to original sources
PubMed1992

Transhiatal and transthoracic esophagectomy for adenocarcinoma of the esophagus.

Adenocarcinoma of the esophagus is no longer rare and is treated by resection. To determine whether the approach used for resection influences outcome, we studied 88 patients who underwent resection; 14 had stage I or II disease, 74 had stage III, and 40 had stage IV. One third of those with Barrett's esophagus were noted on screening endoscopy to have potentially curable disease; the others were diagnosed with stage III or IV disease. Transhiatal esophagectomy was performed in 63 patients; 24 patients underwent transthoracic esophagectomy. We found no difference in survival or morbidity between transhiatal and transthoracic esophagectomy. Overall 5-year survival for stage I and II disease was 86%. For stage III and IV disease, 5-year survival was 14.5%. Aggressive surveillance of Barrett's esophagus facilitates the discovery of early disease. Esophagectomy for adenocarcinoma can result in cure of early cancers and improved palliation of more advanced disease.

Adenocarcinoma↗
PubMed1992

Morphine effects on human colonic myoelectric activity in the postoperative period.

Colonic myoelectrical activity was studied in 25 patients, 18 of whom received morphine sulfate, using bipolar electrodes placed in the ascending and descending colon during laparotomy. Baseline myoelectrical activity was recorded daily, then morphine (3 to 15 mg) was administered intravenously, intramuscularly, or epidurally, and recordings continued. Seven activity patterns were observed during recovery from postoperative ileus. During the first 2 postoperative days, morphine at any dose did not affect colon myoelectrical activity. From the third postoperative day on, morphine given intravenously or intramuscularly initiated clusters of short, nonmigrating, phasic spike bursts occurring on each successive slow wave in 14 of 18 patients, which lasted for 30 to 45 minutes. When morphine was administered epidurally, there was no colonic response in any patient. These findings suggest that: (1) morphine intravenously or intramuscularly induces predominantly nonmigrating colonic spike bursts; (2) morphine-induced activity alters the normal pattern of colonic motility during recovery from postoperative ileus; and (3) these phenomena are not due to direct action of morphine on the spinal cord since epidural morphine had no effect.

Colon↗
PubMed1992

Enterohepatic circulation is essential for regular cycling of duodenal migrating motor complexes in dogs.

The role of enterohepatic circulation and specific bile acids in the initiation and caudad migration of duodenal migrating motor complexes (MMCs) was investigated in conscious dogs. All dogs had spontaneous duodenal MMCs that migrated to the terminal ileum when bile flow was intact. During the first 3 days after total external biliary diversion, no MMCs originated in the duodenum. Instead, all MMCs originated in the jejunum and migrated to the ileum. During the next 4 days of total external biliary diversion, 81% of the MMCs originated in the jejunum and 19% in the duodenum. When normal bile flow was restored after 9 days of total external biliary diversion, regular duodenal MMCs resumed after a delay of 126 +/- 27 minutes. Perfusion of individual bile acids or dogs' own bile, but not saline or alkaline solution, into the duodenum or perfusion of dogs' own bile directly into the ileum during total external biliary diversion restarted duodenal MMCs with a time lag of about 2 hours. The authors conclude that intact enterohepatic circulation is essential for the initiation of regular duodenal MMCs.

Animals↗
PubMed1992

Arginine vasopressin inhibits phasic contractions and stimulates giant contractions in monkey colon.

Abdominal cramps and urgent defecation are common side effects of clinical doses of arginine vasopressin, indicating that the drug may have stimulating effects on colonic motor activity. Four strain-gauge transducers were implanted on the colon in six monkeys. A blood flow probe was fixed on the inferior mesenteric artery. After a 1-hour control recording, vasopressin, 0.13, 1.3, or 13.0 ng.kg-1.min-1, was infused intravenously for 90 minutes. The frequency of basal colonic contractions was reduced with increasing doses of vasopressin, but their mean amplitude and duration were not altered. Giant migrating contractions associated with defecation were initiated by the highest dose of vasopressin. Atropine had no effect on these giant migrating contractions but completely inhibited normal phasic contractions. Hexamethonium completely inhibited both giant migrating contractions and phasic contractions. Parasympathetic denervation of the colon did not inhibit giant migrating contractions initiated by vasopressin. Our findings suggest that the physiological concentrations of serum vasopressin present perioperatively may transiently inhibit spontaneous colon contractions but are unlikely to be the major cause of postoperative ileus. The giant migrating contractions initiated by vasopressin may account for the defecation associated with pharmacological doses of vasopressin. The initiation of giant migrating contractions by vasopressin may be mediated through a neural pathway.

Animals↗
PubMed1992

Antral control of gallbladder cyclic motor activity in the fasting state.

The hypothesis that gastric antrum controls the phasic contractions of gallbladder cyclic motor activity in the fasting state was tested. Gallbladder, gastric, and small bowel motor and myoelectric activity was recorded by strain gauge transducers and bipolar electrodes. Gallbladder pressure was measured manometrically by a surgically implanted intraluminal catheter. After control recordings for 4 to 6 weeks, antrectomy and gastroduodenostomy were performed. Six weeks later, bilateral truncal vagotomy was performed in each dog. Recordings were made after each surgical procedure. In the control state, the gallbladder exhibited cyclic motor activity consisting of phasic contractions at a frequency of 0.75 +/- 0.02/min superimposed on an increase in baseline pressure. Antrectomy and gastroduodenostomy completely abolished the phasic contractions of gallbladder cyclic motor activity and significantly decreased the incidence of the cyclic increase in baseline pressure. Subsequent vagotomy had no additional effect on gallbladder cyclic motor activity. In intact dogs, the gallbladder filled from 0% to 80% and emptied from 80% to 100% of the duodenal migrating motor complex cycle, which was considered to begin at the start of phase I activity. Antrectomy significantly altered this pattern; after antrectomy, the gallbladder filled from 0% to 10% and from 90% to 100% and emptied during the remainder of the duodenal migrating motor complex cycle. Subsequent vagotomy had no additional effect on periodic gallbladder filling and emptying. It is concluded that major changes occur in gallbladder cyclic motor activity and its periodic filling and emptying pattern in the fasting state after antrectomy and vagotomy. It is hypothesized that in the absence of cyclic phasic contractions after antrectomy, periodic stirring and agitation of gallbladder bile and its mixing with fresh hepatic bile may not occur in the fasting state. The absence of this phenomenon may lead to supersaturation of bile near the mucosal surface and increase the propensity for precipitation of salts and formation of gallstones.

Animals↗
PubMed1992

Evaluation of new anti-infective drugs for surgical prophylaxis. Infectious Diseases Society of America and the Food and Drug Administration.

It has been established by substantial research that antimicrobial prophylaxis for various surgical procedures can reduce the risk of postoperative morbidity and mortality. When the incidence of infectious complications is high, the reduction with prophylaxis is most dramatic. However, even for many "clean" procedures (vascular procedures, total joint replacement), the small reduction in potentially calamitous complications justifies the use of prophylaxis. Many issues of detail remain unanswered: timing and duration of administration of antimicrobial drug; type of drug; use of topical anti-infective agents as ancillary measures; and choices for high-risk individuals and others ordinarily excluded from clinical trials. An approach to the conduct of clinical trials of anti-infective drugs for surgical prophylaxis is provided. Both general guidelines and specific recommendations for total hip replacement, colorectal operations, appendectomy, and transurethral resection of the prostate are included.

Anti-Infective Agents↗
PubMed1992

Vagal influence on colonic motor activity in conscious nonhuman primates.

We investigated the role of the vagi in modulation of colonic motor activity in the fasted and fed states and determined the extent of vagal influence on colon motility in conscious monkeys. Monkeys were implanted with force transducers on the colon. A vagal cooling chamber was implanted supradiaphragmatically, and a vagal stimulating electrode was implanted just distal to the chamber. One week was allowed for recovery. After an overnight fast, control recordings were made for 1 h, and then the monkeys were either fed or remained fasting, with or without adrenergic blockade (propranolol and phentolamine). Then while recordings continued the vagi were cooled to their predetermined denervation temperature for 1 h. In a second set of experiments, adrenergic blockers were injected, and the vagi were stimulated during vagal cooling with or without atropine administration. In both the fasted and fed states, the contractile frequency was decreased during vagal cooling, with or without adrenergic blockade. With adrenergic blockade, however, the frequency of colon contractions was greater during cooling than during cooling without such blockade. Inhibition of colonic contractions during cooling decreased in magnitude from the proximal to the distal colon. Vagal efferent stimulation increased contractile frequency at all sites, but after atropine it decreased contractile frequency. We conclude that the vagi have either a direct or indirect influence on fasting and fed colonic motor activity throughout the colon, and that a nonadrenergic, noncholinergic inhibitory pathway is under vagal control.

Animals↗
PubMed1992

Selective adrenergic agonists and colon motility in monkeys.

Sympathetic stimulation during and after laparotomy and other surgical procedures may be a factor inducing postoperative ileus. In experiments conducted in fasting monkeys, the effects of the selective sympathetic agonists alpha 1 (phenylephrine), alpha 2 (ST-91), beta 1 (dobutamine), and beta 2 (terbutaline) on colon contractile activity were measured. Strain gauges were implanted on the colon. Recordings were made for 1 hour (control) and then for an additional hour during continuous infusion by one of a range of doses of each drug (experimental). The drug doses were chosen to cover both physiologic and pharmacologic concentrations. All of the sympathetic agonists caused a dose-dependent decrease in the frequency of colon contractions. The beta-agonists did so at a concentration that is sufficiently low to support a hypothesis that beta-stimulation leading to inhibition of smooth-muscle contraction may play an important role in the genesis of postoperative ileus.

Adrenergic alpha-Agonists↗
PubMed1992

Antibiotic prophylaxis for scheduled operative procedures.

As a result of numerous trials during the past two decades addressing antibiotic prophylaxis for surgical procedures, it has been established that appropriately administered antibiotic prophylaxis reduces the risk of postoperative infection by about 50% when compared with comparable untreated patients. Antibiotics cannot completely eliminate all risk of infection, however, and will never be a substitute for good surgical practices.

Anti-Bacterial Agents↗
PubMed1979

Effective surgical therapy of esophagitis. Experience with Belsey, Hill, and Nissen operations.

During the years 1971 to 1978, 252 patients needed surgical treatment of primary or secondary esophagitis. Major operations performed were 73 Belsey Mark IV repairs, 55 Hill repairs, and 129 Nissen repairs. In the group with primary reflux, barium swallow tests and endoscopy were useful in confirming the diagnosis in patients with typical symptoms; routine biopsy, lower esophageal sphincter, manometry or an acid infusion test did not add to diagnostic certitude. If symptoms were atypical, a biopsy was helpful but manometry and acid infusion were not. Mean symptom scores in this group of patients were improved by each of the "valve-building" operations. Intraoperative dilation after mobilization of the esophagus coupled with a valve-building operation was successful in managing 26 of 29 strictures. Reoperation after an operation failed carried appreciable morbidity and mortality but resulted in good control of symptoms. Addition of a Belsey or Nissen procedure to myotomy for management of primary esophageal motility disorders diminished symptoms and did not cause disabling obstruction.

Collagen Diseases↗
PubMed1979

Preoperative prophylactic cephalothin fails to control septic complications of colorectal operations: results of controlled clinical trial. A Veterans Administration cooperative study.

Data obtained from a survey of the membership of the Society for Surgery of the Alimentary Tract and the American Society of Colon and Rectal Surgeons indicated that concomitant administration of oral neomycin-erythromycin base and systemic cephalothin, together with mechanical colon cleansing, was the most popular method of colon preparation. We designed a prospective double blind clinical trial to compare administration of intravenous cephalothin, oral neomycin-erythromycin base, and the combination of both the intravenous and oral antibiotics. Intake of patients to the intravenous cephalothin group was stopped because the data indicated that this method of prophylaxis resulted in significantly higher numbers of septic complications. The incidence of wound infection was 30 per cent and the overall incidence of septic complications was 39 per cent in patients receiving only intravenous cephalothin combined with mechanical colon cleansing. The incidence of wound infection and the overall incidence of septic complications was only 6 per cent in the comparison group, and the differences are highly significant.

Aminoglycosides↗
PubMed1979

Electromotor feeding responses of primate ileum and colon.

Serosal bipolar electrodes to record spike discharges and strain gauge force transducers to record circular muscle contractions were placed in pairs on the terminal ileum, cecum, right colon at the ileocecal valve, ascending colon, and proximal transverse colon of sixteen primates. After an overnight fast, electromotor responses to continued fasting or to ingestion of a meal (randomized order) were recorded in awake animals. Feeding led to increased spike discharges and increased frequency of muscle contractions at all sites. The onset of these responses usually was within 6 minutes after feeding; the responses increased progressively during 30 to 45 minutes and then remained more or less at a constant plateau of increased activity. Atropine completely blocked the postcibal responses of ileum and proximal colon for up to 30 minutes. Transit time data of labeled meals excluded direct stimulation by a food bolus as the mechanism of the observed postcibal colonic response. The pattern of response was consistent with humoral mediation.

Animals↗
PubMed1979

Effect of dietary fiber on intraluminal pressure and myoelectrical activity of left colon in monkeys.

The effects of varying intake of dietary fiber content on left colon intraluminal pressure, electrical spike discharge activity, and contractions of circular muscle were measured in stump-tailed monkeys. Animals were preconditioned to sit in restraint chairs and then had the sigmoid colon instrumented with an extraluminal strain gage force transducer, a bipolar serosal electrode and a Thomas cannula to provide access for determining luminal pressure with a perfused, open-tip catheter. Diets containing 0, 5, 10, 15, and 20 g of dietary fiber daily were fed in varying sequences for periods of 3 wk. Observations were made twice during the last week of each diet. Fecal weight increased in animals on a high fiber diet, but changing dietary fiber content did not alter the duration of spike discharge activity and produced only a minimal change in the contraciton frequency of colon circular muscle. Colon intraluminal pressure was increased significantly by feeding low-fiber diets, but intraluminal pressure responses did not always correlate with the myoelectrical activity of the colon circular muscle.

Animals↗