The role of the rat hippocampal system in several effects of context in extinction.

The effect of fornix lesions on some effects of manipulating the context on performance in extinction were studied. In renewal, subjects' responding to an extinguished conditioned stimulus (CS) recovered when the CS was presented in the context in which it had been conditioned after extinction in a different context. In reinstatement, it recovered when the CS was tested after independent presentation of the unconditioned stimulus (US; an effect mediated by contextual conditioning.) In spontaneous recovery, it recovered after the passage of time, that is, when the CS was tested in a new temporal context. In the conditioned suppression method, fornix lesions had no effect on conditioning, extinction, renewal, or spontaneous recovery; however, they abolished the reinstatement effect. The results suggest that the hippocampal system may be important in the formation of context-US associations, but not in other types of learning about the context.

Extinction and spontaneous recovery of ataxic tolerance to ethanol in rats.

RATIONALE AND OBJECTIVES: Two experiments with rats using an ethanol ataxia method investigated extinction and spontaneous recovery of tolerance. Tolerance extinction has been shown with a variety of drugs and methods, but until now it has not been shown with ethanol ataxia. Extinction was investigated here because of its connection with cue exposure treatments, and also to allow an assessment of spontaneous recovery. Spontaneous recovery is the return of conditioned responses, such as those potentially contributing to tolerance, when time passes after extinction. In terms of response topography it resembles instances of relapse in humans. Its demonstration constitutes one technique for illustrating that the effects of extinction are often temporary. There are no published reports showing a recovery of tolerance to any drug due to the passage of time after extinction. A demonstration of spontaneous recovery contributes to an understanding of the effects and time course of tolerance extinction. It also raises the possibility that spontaneous recovery involving drug tolerance has mechanisms similar those involved in instances of spontaneous recovery studied more extensively with non-drug methods. METHODS: In one experiment, ataxic tolerance was conditioned to a strobelight conditioned stimulus (CS) by exposing rats to the strobelight while experiencing the effects of an ethanol injection. Tolerance was extinguished in 17 or 24 once-daily trials by presenting the strobelight without ethanol (with saline). The effect of those numbers of trials was assessed on the day after extinction in the presence of the strobelight when ethanol was again injected. The effect was compared to the effect of the strobelight and ethanol in naive rats and in rats that had received only tolerance conditioning. In a second experiment, ataxic tolerance was conditioned and then extinguished over 17 trials, just as in the other experiment. Different groups were then tested 1, 12, 18, and 24 days after extinction in the presence of the strobelight when ethanol was again injected. RESULTS: Ataxic tolerance was fully extinguished after either 17 or 24 trials, as shown by comparisons with the naive and conditioning-only controls. Tolerance was greater (it recovered) when the strobelight CS was reintroduced 24, 18, and even 12 days after extinction, compared with testing 1 day after extinction. CONCLUSIONS: Conditioned ataxic tolerance can be extinguished, just as other conditioned tolerances can. More important, the return of tolerance over time after extinction represents spontaneous recovery of ethanol tolerance, and indicates that as in other conditioning preparations, extinction does not result in unlearning of the original conditioning association. The identification of spontaneous recovery of tolerance isolates a robust source of the potential for drug use relapse: the mere passage of time after extinction.

Chronic pancreatitis secondary to an inflammatory polyp of the duodenum 25 years after Billroth II reconstruction.

A 51-year-old man, 25 years after undergoing Billroth II gastrojejunostomy with antrectomy and vagotomy, came to our hospital with acute relapsing pancreatitis. At operation he was found to have an inflammatory polypoid lesion at the duodenal stump that consisted of suture and talc granuloma from his previous gastric surgery. The polyp intermittently obstructed the pancreatic duct, causing symptomatic pancreatitis. The patient has remained without symptoms 2 years after submucosal resection of this polyp. This complication of Billroth II gastroenterostomy has not been recognized previously.

Rapid development of umbilical metastases after laparoscopic cholecystectomy for unsuspected gallbladder carcinoma.

Unsuspected microscopic adenocarcinoma of the gallbladder was identified after operation in a 66-year-old woman undergoing elective laparoscopic cholecystectomy for symptomatic cholelithiasis. An abdominal wall metastasis developed at the periumbilical incision site through which the laparoscope was introduced and through which the gallbladder was removed. A review of the available information on tumor seeding of laparoscopic tracts and drain tracts is presented, as well as implications for the further management of gallbladder cancer and other intraabdominal malignancies.

Epinephrine acutely mediates skeletal muscle insulin resistance.

Alterations in carbohydrate metabolism and insulin resistance are major features of the metabolic response to injury. The mediators of these changes are not defined. In this study we investigated the influence of epinephrine on insulin-mediated glucose uptake by peripheral tissue. Forearm blood flow and substrate exchange were determined during insulin clamp studies with and without epinephrine infusion in normal persons. During control studies insulin concentration was raised to 103 +/- 5 microU/ml. Whole body glucose disposal was 9.23 +/- 1.01 mg/kg . min. At a comparable level of hyperinsulinemia (93 +/- 4 microU/ml), epinephrine reduced glucose disposal to 4.54 +/- 0.39 mg/kg . min (P less than 0.01). Forearm glucose uptake was reduced from 0.66 +/- 0.08 to 0.18 +/- 0.13 mg/100 ml . min (P less than 0.05) despite a doubling of forearm blood flow. Epinephrine reduces whole body glucose disposal in part by reducing glucose uptake in peripheral tissue, primarily muscle. Epinephrine-induced skeletal muscle insulin resistance may play a major role in insulin-resistant states and may contribute to accelerated protein catabolism seen following injury.

Surgical therapy for thyroid carcinoma: a review of 1249 solitary thyroid nodules.

A total of 1249 "cold" solitary thyroid nodules were excised at the Brigham and Women's Hospital from 1948 through 1987. Of these nodules, 241 showed malignant conditions: 123 were papillary, 42 were mixed papillary-follicular, and 43 were pure follicular carcinomas. There were also 23 anaplastic, 8 medullary, and 3 Hürthle cell carcinomas. These patients were followed up from 3 to 31 years, with a mean range of 10 years. Fifty-three patients with well-differentiated tumors underwent total thyroidectomies, and 179 underwent subtotal thyroidectomies (excluding anaplastic, medullary, and Hürthle cell tumors). Regional lymph node involvement was commonly found but appeared not to affect survival; tumor size and local spread and extent of thyroid gland involvement did affect survival. A small percentage of well-differentiated thyroid tumors do, in time, undergo anaplastic change that leads to metastasis and death. There was no 30-day mortality rate. The late mortality rate was 2% for papillary and 14% for follicular carcinomas. Papillary tumors are becoming more common. Older aged patients and male patients appear to carry poorer prognoses for survival. The total thyroidectomy procedure has not improved survival over subtotal thyroidectomy and carries a higher complication rate.

A prospective comparison of laparoscopic and tension-free open herniorrhaphy.

OBJECTIVE: To compare results and outcomes following laparoscopic and tension-free open inguinal herniorrhaphy. DESIGN: A prospective, nonrandomized trial of a single surgeon's experience. SETTING: A large university hospital. PATIENTS: The study included 100 patients with 116 hernias. Patients were offered open hernia repair or, if medically suitable for general anesthesia, a laparoscopic hernia repair. Fifty-seven patients underwent open repair and 43 patients underwent laparoscopic repair. INTERVENTION: Laparoscopic repair was performed using a transabdominal preperitoneal mesh technique. Open hernia repair was performed using a mesh-plug technique in which the hernia sac was reduced and held in place by a cone of mesh. The floor was covered with a second piece of mesh that encircled the cord and was sutured at the internal ring; it was held in place under the external oblique without sutures. RESULTS: Patients undergoing open repair were older than those undergoing laparoscopic repair. The distribution of hernia types was similar. The laparoscopic operation took longer than the open operation (mean [+/- SD], 1.9 +/- 0.4 hours vs 1.6 +/- 0.4 hours; P < .05), was more expensive ($4165 +/- $1154 vs $2985 +/- $1682; P < .05), and required more postoperative admissions (28% vs 3.5%). There were three recurrences in the laparoscopic group and none in the open group. Patients undergoing laparoscopic repair consumed the same amount of narcotic analgesics as did the group undergoing open repair and had discomfort for the same amount of time. Patients undergoing laparoscopic repair returned to work sooner than did patients undergoing open repair (5.6 days vs 10.3 days; P < .05). CONCLUSIONS: Laparoscopic hernia repair returns patients to the workplace faster than open hernia repair despite a similar analgesic requirement. The laparoscopic repair costs more and has a higher recurrence rate than open repair. Laparoscopic repair is most suitable for bilateral hernias. Further investigation of this technique is required before its wide-scale application can be recommended.

Patient satisfaction following laparoscopic and open antireflux surgery.

OBJECTIVE: To compare laparoscopic (LNF) with open Nissen fundoplication (ONF) in terms of hospital charges, efficacy, and patient satisfaction. DESIGN: A prospective, nonrandomized study with a median follow-up of 370 days. SETTING: Two tertiary care university hospitals. PATIENTS: Eighty-six patients with complications of gastroesophageal reflux who had not had previous antireflux surgery were studied. Patients chose ONF or LNF following discussion with the surgeon; 12 underwent ONF and 74 underwent LNF, of whom eight required conversion to laparotomy. MAIN OUTCOME MEASURES: Hospital charges, disability, satisfaction, and side effects of fundoplication. RESULTS: Patients were demographically similar. Total charges (mean +/- SD) for LNF ($11,673 +/- $4723) were significantly less than for ONF ($18,394 +/- $17,264). Patients who underwent LNF returned to work sooner (10 +/- 3 days) than those who underwent ONF (28 +/- 1 days). Bloating, dysphagia, and recurrent heartburn occurred with equal frequency in both groups. Recurrent reflex occurred in four of 74 LNF patients and one of 12 ONF patients. Overall satisfaction scores were similar, irrespective of operative technique (LNF, 3.35 +/- 0.87; ONF, 3.50 +/- 0.94. CONCLUSIONS: Laparoscopic Nissen fundoplication is as effective as ONF in the treatment of complications of gastroesophageal reflux disease and appears to cost less and lead to faster recovery from surgery, but does not result in higher patient satisfaction than ONF. The most important factor in patient satisfaction is the abolition of preoperative symptoms rather than the type of operation.

Predictive factors for unanticipated admissions after ambulatory laparoscopic cholecystectomy.

HYPOTHESIS: Analysis of the causes of unanticipated admission after ambulatory laparoscopic cholecystectomy may permit the identification of predictive clinical factors for postoperative admission. DESIGN: Univariate and multivariate analyses of clinical variables associated with unplanned admission in a retrospective case-control series of ambulatory laparoscopic cholecystectomies. SETTING: A major university-affiliated teaching hospital. PATIENTS: Seven hundred thirty-one consecutive patients who underwent ambulatory laparoscopic cholecystectomies between January 1, 1996, and December 31, 1999. INTERVENTION: Ambulatory laparoscopic cholecystectomy. MAIN OUTCOME MEASURES: Unplanned postoperative admissions. Univariate and multivariate analyses of 19 clinicopathologic factors were performed to identify independent predictive factors for these admissions. RESULTS: Seven hundred six patients were discharged on the day of operation. The remaining 25 required admission because of pain (n = 10), nausea and vomiting (n = 6), retention of urine (n = 5), patient preference (n = 3), and medical observation (n = 1), giving an unanticipated admission rate of 3.4%. Significant factors associated with unplanned admission included operative duration of longer than 60 minutes and thickened gallbladder wall on ultrasonographic and pathological findings. By means of logistic regression, length of operation was the only independent predictive factor. Operative time exceeding 60 minutes incurred a 4-fold increased risk for unanticipated admission. CONCLUSIONS: Operative duration was the best predictive factor for unplanned admission after ambulatory laparoscopic cholecystectomy. During selection of patients for day surgery, ultrasonographic demonstration of a thickened gallbladder wall should be taken into consideration.

Routine cholangiography is not warranted during laparoscopic cholecystectomy.

The role of intraoperative cholangiography during laparoscopic cholecystectomy was prospectively evaluated in 514 patients undergoing laparoscopic cholecystectomy. Before surgery, all patients were assigned to one of three groups depending on the likelihood of their having common bile duct stones. Stratification was based on objective historical, laboratory, or radiologic criteria. In 453 patients deemed unlikely to have stones, laparoscopic cholecystectomy was performed without cholangiography. Of these patients, four had retained stones (0.9%). In 25 patients likely to have stones, preoperative endoscopic retrograde cholangiopancreatography identified stones in six patients (24%). In 36 patients whose likelihood of having stones was deemed indeterminate, intraoperative cholangiography was performed at laparoscopic cholecystectomy. A common bile duct stone was identified in one patient (2.8%). One common bile duct injury occurred in the group deemed unlikely to have stones, and this injury would not have been prevented by intraoperative cholangiography. We conclude that preoperative assessment will identify common bile duct stones and that routine cholangiography is not warranted. Meticulous dissection of the cystic duct at its origin at the infundibulum will prevent common bile duct injury.

Microscopic appearance of the human fallopian tube following a reanastomosis procedure.

Microscopic evaluation of a human fallopian tube following end-to-end anastomosis over a polyethylene stent was performed 10 days after the initial surgical procedure. The stent was removed on the 3rd postoperative day. Examination of the excised tube revealed a patent lumen without any evidence of mucosal compromise. The submucosa adjacent to the anastomotic site revealed a mild polymorphonuclear leukocytic infiltration, although a marked inflammatory response was observed around the 5-0 chromic sutures used in the reanastomosis. This case and recent animal studies suggest that early removal of the stent does not appear to jeopardize the patency of the tube and may be preferable to removal after 3 to 4 months.

A retrieval cue for extinction attenuates spontaneous recovery.

Four experiments with rats in an appetitive conditioned magazine entry preparation examined spontaneous recovery after extinction. Spontaneous recovery was obtained 6 days but not 5 hr following extinction; recovery depended on the passage of time but not on the removal of a cue that was featured in extinction or on the reintroduction of early-session cues. A cue featured in extinction attenuated recovery when presented on the test. The attenuation effect depended on the cue's correlation with extinction; a cue featured in conditioning did not attenuate recovery. The extinction cue did not evoke responding on its own, suggesting that it was not a conditioned excitor. Retardation tests and a summation test did not reveal that it was a conditioned inhibitor. The cue might work by retrieving a memory of extinction. Spontaneous recovery thus occurs because the subject fails to retrieve an extinction memory. Other accounts of spontaneous recovery are discussed.

High-resolution real-time ultrasonography. A new tool in the diagnosis of acute appendicitis.

A prospective study was performed to assess the sensitivity and specificity of ultrasonographic evaluation in 44 patients with suspected appendicitis. We found ultrasonographic evaluation to have a sensitivity rate of 89 percent, a specificity rate of 86 percent, and an overall accuracy rate of 87 percent. These results are very similar to those in other recently reported studies. We also identified certain patients in whom nondiagnostic studies are likely. Our results suggest that ultrasonographic evaluation may be of particular use in selected patients who do not demonstrate the classical signs and symptoms of acute appendicitis.

Evaluation of palliative procedures for pancreatic cancer.

In a retrospective review of 51 patients undergoing palliative procedures for carcinoma of the pancreas from 1974 to 1979, cholecystoenterostomy was as effective as choledochoenterostomy. Patients with loops had the same incidence of cholangitis as those with Roux-Y limbs. Prophylactic gastroenterostomy was not performed routinely. Few patients needed a later gastroenterostomy for progressive cancer.

Patterns of failure after surgical cure of large liver tumors. A change in the proximate cause of death and a need for effective systemic adjuvant therapy.

During a period of 7 years, we have aggressively treated liver tumors whether primary or metastatic. Our experience after 43 curative major liver resections has shown an excellent overall survival: 34 of 43 patients still alive a median of 12 months after liver resection (patient ages ranged from 21 to 85 years, median 57 years). Nineteen patients underwent right hepatic lobectomy, 9 trisegmentectomy, 5 left hepatic lobectomy, 5 extended left hepatic lobectomy, 4 right lobectomy plus left lobe wedge resection, and 1 patient underwent a major hilar wedge resection. Two patients died from sepsis and hepatic failure on or before the 60th postoperative day. One patient with no evidence of recurrent colorectal cancer was lost to follow-up after 2.5 years. One patient died without cancer 12 months after left hepatic lobectomy for colon cancer metastases. Cumulative survival for the entire series and for patients after resection of colorectal cancer metastases was the same: 1 year survival 90 percent; 2 year survival 75 percent, and 3 year survival 65 percent. Seventeen of 30 patients remain disease-free after resection of liver metastases. Of the 13 who had recurrence, 8 are still alive. Ten recurrences were outside of the residual liver (predominantly multiple pulmonary metastases). One recurrence was in the right hemidiaphragm, and only three were in the residual or regenerated liver. Serial carcinoembryonic antigen analysis was the best indicator of recurrence in these 13 patients, 12 of whom were asymptomatic. These data confirm that major liver resection can be performed with minimum postoperative mortality (4.7 percent in this series). More importantly, the majority of patients were cured of their liver metastases. The next goal should be the initiation of adjuvant systemic therapy trials after liver resection in such patients.

Laparoscopic cholangiography. The case for a selective approach.

Intraoperative cholangiography has proved to be a significant benefit for the biliary surgeon by alleviating the morbidity of unnecessary common duct exploration in patients with suspected but unproved choledocholithiasis and by clarifying biliary anatomy in patients when dissection proves difficult. Laparoscopic surgeons should be capable of performing the procedure when indicated and should be comfortable interpreting the images obtained. Laparoscopic cholecystectomy with selective application of cholangiography can be performed with little or no effect on the incidence of retained calculi, with no impact on the incidence of common bile duct injury, and with diminished operative time and expense. The experienced laparoscopic surgeon can become facile with the procedure quickly and easily and does not require routine performance of the study to maintain these skills. Reduction of the incidence of biliary injury during laparoscopic cholecystectomy can be achieved by early meticulous dissection at the infundibular-cystic duct junction, with limited use of laser or electrocautery in this region rather than by reliance on intraoperative cholangiography.

The heated dorsal hand vein: an alternative arterial sampling site.

Studies of substrate flux, isotope activity and metabolic balance frequently require arterial sampling. We evaluated: (1) whether substrate concentrations obtained from heated dorsal hand veins (HDHV) were comparable to samples obtained from the radial artery, (2) whether heat sufficient to arterialize HDHV altered contralateral forearm blood flow thus affecting flux calculations, (3) whether a +14 heating pad equaled a cumbersome +700 heating chamber, and (4) whether HDHV showed a dose-response curve to varying heat loads. In 12 normals, dorsal hand temperature was raised from 31.8 +/- 0.6 degrees C to 39.8 +/- 0.8 degrees C (chamber) and 39.3 +/- 0.3 degrees C (pad). Basal contralateral forearm blood flow (3.37 +/- 0.7 ml/100 ml tissue/min) was not significantly altered in the chamber (3.39 +/- 0.5 ml) or the pad (3.44 +/- 0.5 ml). Skin temperature of the unheated hand, an index of superficial blood flow (31.5 +/- 0.7 degrees C) did not change significantly in the chamber (31.6 +/- 0.7 degrees C) or the pad (31.2 +/- 0.7 degrees C). Forearm blood flow did not change with heating in eight postoperative patients. Comparative arterial and HDHV blood gases and 10 metabolic substrates from simultaneously drawn samples at various temperatures showed HDHV PO2 approached but did not equal arterial PO2 at temperatures greater than 39 degrees C. Glucose, amino acid, and substrate concentrations were comparable at 39 degrees C and did not change with increasing temperature. HDHV can reliably determine arterial substrate concentrations using an inexpensive heating pad. In cool environments (20-22 degrees C), contralateral forearm blood flow is not significantly altered. There is no benefit to heating the hand above 39 degrees C.

Transitions in laparoscopic cholecystectomy: the impact of ambulatory surgery.

BACKGROUND: Ambulatory laparoscopic cholecystectomy is a common practice in the United States, but its development remains slow in most other countries. The objective of the current study was to report the impact of ambulatory surgery on the practice of laparoscopic cholecystectomy in a major teaching hospital since the inception of the service. METHODS: The hospital database of patients who underwent cholecystectomies for benign hepatobiliary pathologies was reviewed between January 1993 and December 1999. Changes in the practice of laparoscopic cholecystectomy and the length of hospital stay were analyzed. Clinical characteristics of the ambulatory and inpatient groups were compared. RESULTS: Of 2,891 laparoscopic cholecystectomies involved in the current study, 888 (31%) were performed as day cases, and 2,003 (69%) were performed as inpatient laparoscopic cholecystectomies. The annual number of ambulatory laparoscopic cholecystectomies increased from 3 (0.6%) in 1993 to 212 (48%) in 1997. This was followed by a plateau in the next 3 years. The ambulatory group comprised a significantly higher prevalence of young women (87%) who underwent surgery mainly for biliary colic (88%). CONCLUSIONS: The current study demonstrated a net trend toward ambulatory laparoscopic cholecystectomy and a shorter length of hospital stay. Almost half of our patients with gallstone disease currently are using the ambulatory laparoscopic cholecystectomy service, with young women constituting the majority. We predict that ambulatory laparoscopic cholecystectomy heralds the wave of the future, and our experience may serve as a blueprint for other institutions wishing to embark on this journey.

What is the value of telerobotic technology in gastrointestinal surgery?

BACKGROUND: Although telerobotic technology has entered clinical application, its value for gastrointestinal surgery is unclear. Our objective was to evaluate the performance characteristics of telerobotically assisted laparoscopic cholecystectomy (TALC). METHODS: All TALCs performed using the da Vinci Surgical System between January 2000 and September 2001 at a tertiary academic medical center were analyzed. RESULTS: For this study, 20 patients (80% female) with a mean age of 47 +/- 4 years underwent TALC. All had symptomatic cholelithiasis, and all had successful TALC results without complications or need for conversion to conventional laparoscopic cholecystectomy (CLP). The mean procedure time was 152 +/- 8 min. The procedures were performed by one of three staff surgeons experienced in laparoscopic surgery who had training in telerobotic surgery. The perceived advantages of TALC over CLP included easier tissue dissection, enhanced dexterity, and stimulated interest in biliary surgery. The disadvantages included increased operating time and lack of tactile feedback. CONCLUSIONS: The TALC procedure is effective and safe when performed by appropriately trained surgeons. Telerobotic technology has the potential to reinvigorate gastrointestinal surgery.

Intraoperative use of a 2-mm choledochoscope for the exploration of small bile ducts and the pancreatic duct.

Intraoperative visualization of the biliary and pancreatic ducts can be difficult in a nondilated system. Very small extra- and intrahepatic bile ducts occasionally require visualization but do not admit the traditional 6.5-mm intraoperative flexible choledochoscope. We have prospectively examined the use of a 2-mm choledochoscope for the intraoperative evaluation of the biliary and pancreatic ducts in 36 patients. In 27 patients, the choledochoscope was advanced through the cystic duct stump for examination of the common bile duct following cholangiography. The scope was successfully passed into the cystic duct stump and into the common bile duct in 76 per cent of patients. Inability to pass the scope through the cystic duct was usually due to acute angulation of the cystic duct/common duct junction. In an additional five patients, intraoperative cholangiography revealed a filling defect in a very small duct. A choledochotomy was made and the 2-mm choledochoscope was used to exclude the presence of stones in a small bile duct. In four patients the choledochoscope was used during a Puestow procedure to visualize and help extract stones in the tail and head of the gland. No complications occurred in these patients due to the use of the choledochoscope. We conclude that the 2-mm choledochoscope aids in internal visualization of small intra- and extrahepatic bile ducts and the pancreatic duct. It may be useful as an adjunct to cholangiography in determining the nature of filling defects.