Refinement of eDNA as an early monitoring tool at the landscape-level: study design considerations

Natural resource managers use data on the spatial range of species to guide management decisions. These data come from survey or monitoring efforts that use a wide variety of tools. Environmental DNA (eDNA) is a surveillance tool that uses genetic markers for detecting species and holds potential as a tool for large-scale monitoring programs. Two challenges of eDNA-based studies are uncertainties created by imperfect capture of eDNA in collection samples (e.g., water field samples) and imperfect detection of eDNA using molecular methods (e.g., quantitative PCR). Occurrence models can be used to address these challenges, thus we use an occurrence model to address two objectives: first, to determine how many samples were required to detect species using eDNA; second, to examine when and where to take samples. We collected water samples from three different habitat types in the Upper Mississippi River when both Bighead Carp and Silver Carp were known to be present based on telemetry detections. Each habitat type (backwater, tributary, and impoundment) was sampled during April, May, and November. Detections of eDNA for both species varied across sites and months, but were generally low, 0-19.3% of samples were positive for eDNA. Overall, we found that eDNA-based sampling holds promise to be a powerful monitoring tool for resource managers; however, limitations of eDNA-based sampling include different biological and ecological characteristics of target species such as seasonal habitat usage patterns as well as aspects of different physical environments that impact the implementation of these methods such as water temperature.

Enterprise Zones: 2. A Comparative Analysis of Zone Performance and State Government Policies

This is the second of two papers in which the programmatic structure and effectiveness of state government designated enterprise zones (EZs) are analyzed. With use of data on EZs from 14 states, the relationships are examined between job and/or investment gains and variables reflecting different state policies, zone locations, and zone settings. It is argued that, if states wish to purse EZ policies, they should focus on a small number of ‘retrievable’ zones, adopt a broad and quality package of business incentives, use no more restrictive designation criteria than needed, explore the possibilities of more direct targeting of existing state development activities into the zones, and seek strong local participation in the promotional effort.

Enterprise Zones: 1. Investment and Job Creation of State Government Programs in the United States of America

This is the first of two papers in which the programmatic structure and effectiveness of state government designated enterprise zones (EZs) in the United States of America are analyzed. The study is based on survey data from 17 states. Although the EZs are not the ‘miracle cure’ for economically distressed areas, as claimed by many proponents, notable investment and job gains have been achieved in many zones. Some traditional arguments against EZs, such as their presumed attraction of ‘sweatshop’ industries, the pirating of existing firms from surrounding areas, and the failure to provide jobs for zone residents are not substantiated. In the second paper, a comparative analysis of the effectiveness of state EZ policies is undertaken, with a focus on differences in zone settings and program structures.

The No Endosonographic Detection of Tumor (NEST) Study: a case series of pancreatic cancers missed on endoscopic ultrasonography

BACKGROUND AND STUDY AIMS

The purpose of this study was to identify possible associated factors that may have contributed to failure to detect a pancreatic neoplasm during endoscopic ultrasound (EUS) examinations by experienced endosonographers.

PATIENTS AND METHODS

A multicenter retrospective study was organized, and 20 cases of pancreatic neoplasms missed by nine experienced endosonographers were identified. Careful analysis of each case was carried out to identify the factors that might have led to the missed diagnosis on EUS.

RESULTS

Twelve patients with a missed pancreatic neoplasm had EUS features of chronic pancreatitis. Other factors that might have increased the likelihood of a false-negative EUS examination included a diffusely infiltrating carcinoma (n = 3), a prominent ventral/dorsal split (n = 2), and a recent episode (within the previous 4 weeks) of acute pancreatitis (n = 1). Five patients with a negative initial EUS underwent a follow-up EUS after 2-3 months, with a pancreatic mass being found in all cases. Three patients had a diffusely infiltrating pancreatic adenocarcinoma.

CONCLUSIONS

EUS is not a foolproof method of detecting a pancreatic neoplasm. Possible associated factors that may increase the likelihood of a false-negative EUS examination include chronic pancreatitis, a diffusely infiltrating carcinoma, a prominent ventral/dorsal split and a recent episode (< 4 weeks) of acute pancreatitis. If there is a high clinical suspicion of pancreatic neoplasm, if EUS and other imaging methods are negative, and if the patient does not undergo surgery, this study suggests that a repeat EUS after 2-3 months may be useful for detecting an occult pancreatic neoplasm.

EUS with EUS-guided fine-needle aspiration as the first endoscopic test for the evaluation of obstructive jaundice

BACKGROUND

This study assesses the cost savings associated with using endoscopic ultrasound (EUS) before endoscopic retrograde cholangiopancreatography (ERCP) for evaluating patients with suspected obstructive jaundice.

METHODS

One hundred forty-seven patients with obstructive jaundice of unknown or possibly neoplastic origin had EUS as their first endoscopic procedure. With knowledge of the final diagnosis and actual management for each patient, their probable evaluation and outcomes and their additional costs were reassessed assuming that ERCP would have been performed as the first endoscopic procedure. Also calculated were the additional costs incurred if EUS were unavailable for use after ERCP and had to be replaced by computed tomography or other procedures.

RESULTS

The final diagnoses in these patients included malignancies (65%), choledocholithiasis or cholecystitis (18%), "medical jaundice" (11%), and miscellaneous benign conditions (6%). Fifty-four percent had EUS-guided fine-needle aspiration but only 53% required ERCP after EUS. An EUS-first approach saved an estimated $1007 to $1313/patient, but the cost was $2200 more if EUS was unavailable for use after ERCP. Significant savings persisted through sensitivity analysis.

CONCLUSIONS

Performing EUS with EUS-guided fine-needle aspiration as the first endoscopic procedure in patients suspected to have obstructive jaundice can obviate the need for about 50% of ERCPs, helps direct subsequent therapeutic ERCP, and can substantially reduce costs in these patients.

Plexosarcoma: endoscopic ultrasound and electron-microscopic characteristics of a stromal tumor

Endoscopic ultrasound is useful for managing submucosal masses; however, some of these lesions can be difficult to classify except with full histological and electron microscopic evaluation. A 72-yr-old woman was seen with upper GI bleeding. Endoscopy showed a 1.7-cm sessile ulcerated submucosal mass in the duodenal bulb. Endoscopic ultrasound revealed an echolucent submucosal mass arising from the fourth echolayer, the muscularis propria of the duodenal wall. These findings suggested that the lesion was a leiomyoma. The patient eventually had the lesion resected because of recurrent bleeding. Histologically it was a spindle cell tumor that on electron microscopy showed neuronal elements consistent with a plexosarcoma, or gastrointestinal autonomic nerve tumor. These lesions account for some one third of all gastrointestinal stromal tumors. Despite their low grade malignant histologic appearance, local recurrence or hepatic metastases occur in about 70% of patients.

Evaluation of mediastinal masses by endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration

OBJECTIVE

Interest has been growing in using endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration in the evaluation of mediastinal masses. The purpose of this study was to review the spectrum of mediastinal masses encountered using endoscopic ultrasound.

METHODS

We reviewed all cases of mediastinal masses examined by endoscopic ultrasound, with or without endoscopic ultrasound-guided fine needle aspiration, prospectively gathered from our electronic database from April 1995 to July 2000.

RESULTS

Of 1447 upper endoscopic ultrasound examinations, 33 (2.3%) involved a mediastinal mass. Sixty-one percent of the patients were male and the average age was 65 yr. Fifty-five percent of patients had dysphagia, 48 percent experienced weight loss, and only 12 percent were totally asymptomatic. Seventy-three percent had masses by chest CT. Sixty-seven percent were ultimately found to be malignant, 21 percent were solid benign lesions, and four were cystic. Only two lesions were resected. Endoscopic ultrasound-guided fine needle aspiration was used in 76 percent of all patients. The median survival of patients with malignant lesions was only 87 days.

CONCLUSIONS

Lesions of the deep mediastinum are often difficult to conclusively diagnose with nonendoscopic studies. Endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration can easily access this region to aid in the diagnosis and management of these lesions.

Impact of endoscopic ultrasound on the management and outcome of pancreatic carcinoma

OBJECTIVE

Although endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration have been shown to aid in the diagnosis and staging of pancreatic carcinoma, whether the general use of these new techniques impacts the overall management and survival of pancreatic cancer, is less clear.

METHODS

Clinical data on all patients diagnosed with pancreatic carcinoma were assessed for two equal time periods during which computerized tomography-guided fine needle aspiration and biopsy was used (1/93-5/95) and then during which endoscopic ultrasound-guided fine needle aspiration was used (8/95-12/97) for the primary diagnosis of these patients.

RESULTS

Comparative data for the computerized tomography era versus the endosonography era showed that 1) pancreatic carcinomas diagnosed: 52 versus 84 patients (stage I-III at diagnosis: 33% vs 54%; p < 0.05); 2) diagnosis by aspiration or biopsy of a pancreatic mass, nodes, liver metastasis, or by operation: 46%, 0%, 19%, 29% versus 52%, 8% (p = 0.02 nodes plus pancreatic masses), 20%, 7% (p = 0.002); 3) pancreatic resections: 13% versus 14%; 4) median survival without liver metastases: 102 versus 205 days (p < 0.02, log-rank test). Endoscopic ultrasound detected carcinomas that were either not seen or only possibly seen by computed tomography in 34%.

CONCLUSIONS

More patients (62%) were diagnosed with pancreatic carcinoma when using endoscopic ultrasound and 75% fewer required operations for diagnosis. The 3-month improvement in median survival is probably multifactorial but most likely represents lead bias because of the greater sensitivity of endoscopic ultrasound for pancreatic carcinoma. Using endoscopic ultrasound with endoscopic ultrasound-guided fine needle aspiration in patients with pancreatic carcinoma significantly affects their management and outcomes.

Clinical utility of endoscopic ultrasound and endscopic ultrasound-guided fine needle aspiration in retroperitoneal neoplasms

OBJECTIVE

Nonpancreatic, retroperitoneal tumors are a relatively uncommon clinical problem. With the advent of endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration, gastroenterologists may be called upon to assist in the diagnosis and management of these lesions. This paper reviews the spectrum of upper retroperitoneal lesions encountered at a single institution using endoscopic ultrasound.

METHODS

We reviewed all cases of nonpancreaticobiliary or nonadrenal retroperitoneal lesions prospectively gathered from our endoscopic ultrasound database from April 1995 to September 1999.

RESULTS

Of 1120 upper endoscopic ultrasound examinations, 18 (1.6%) involved a retroperitoneal lesion; 16/18 lesions were neoplasms, nine were primary retroperitoneal tumors (four lymphomas, two leiomyosarcomas, two extraadrenal paraganglionomas, one leiomyoma), and seven were metastatic cancers. There was one fibrous mass and one mass-like abscess. Endoscopic ultrasound-guided fine needle aspiration was used in 15/18 cases. The management of 16 patients was significantly affected by the results of endoscopic ultrasound and biopsy.

CONCLUSIONS

Although it is not a frequent indication, assessing upper retroperitoneal tumors with endoscopic ultrasound and endoscopic ultrasound-guided fine needle aspiration can significantly affect the subsequent management of patients with these lesions.

Factors predicting the number of EUS-guided fine-needle passes for diagnosis of pancreatic malignancies

BACKGROUND

The factors that affect the number of needle passes needed to diagnose pancreatic malignancies using endoscopic ultrasound (EUS) -guided fine-needle aspiration are unknown.

METHODS

Patient and endosonographic data were prospectively recorded on 121 consecutive patients with pancreatic malignancy. Of these, 110 underwent EUS-guided fine-needle aspiration. A cytopathologist was in attendance for all aspiration procedures.

RESULTS

Initial EUS detected a pancreatic mass in 96% of cases; 23% of these were not seen by computed tomography. EUS-guided fine-needle aspiration was performed in 109 of 110 (99%) patients, including 95 masses, 7 lymph nodes, and 7 hepatic metastases. EUS-guided fine-needle aspiration provided a cytologic diagnosis of malignancy in 104 of 110 (95%). Only tumor differentiation and the site of aspiration affected the number of passes.

CONCLUSIONS

With the participation of a cytopathologist, EUS-guided fine-needle aspiration can diagnose pancreatic malignancies with a high degree of accuracy. Only the aspiration site (mass versus node/liver metastasis) can be used to direct the number of passes if a cytopathologist is not present. Without a cytopathologist in attendance, 5 to 6 passes should be made for pancreatic masses and 2 to 3 for liver metastases or lymph nodes; however, this approach will be associated with a 10% to 15% reduction in definitive cytologic diagnoses, extra procedure time, increased risk and additional needles.

Endoscopic ultrasound and fine needle aspiration for the evaluation of pancreatic masses

HYPOTHESIS

Endoscopic ultrasound (EUS) and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) are accurate for the preoperative staging of pancreatic ductal carcinoma.

DESIGN

Retrospective medical record review.

PATIENTS

A prospective registry of 98 patients having EUS-FNA for peripancreatic masses from April 1994 to April 1998 was analyzed.

MAIN OUTCOME MEASURE

The accuracy of EUS-FNA for preoperative diagnosis and staging of peripancreatic neoplasms.

RESULTS

Ninety-eight patients, aged 41 to 91 years (mean age, 67 years) with peripancreatic masses were evaluated by EUS-FNA. All patients had initial computed tomography scanning with a mass seen in 49 patients, "fullness" to the pancreas in 28 patients, and no mass seen in 21 patients. Evaluation with EUS-FNA revealed 22 benign lesions, 18 T2 masses, 37 T3 masses, 1 T4 mass, and 20 masses representing nonpancreatic tumors. Results of EUS-FNA of adjacent lymph nodes were positive in 27 patients. Twenty-seven patients had surgical resection or palliation permitting operative and pathologic staging. On comparison of EUS-FNA staging with surgical staging, 12 patients were the same stage, 14 patients were upstaged, and 1 patient was downstaged. The remaining patients who did not have surgery have been followed up for a mean of 15 months. Overall accuracy of EUS-FNA for differentiating benign from malignant masses was 96%.

CONCLUSIONS

Endoscopic ultrasound-guided fine needle aspiration is a useful technique for the evaluation of pancreatic masses. It is highly accurate for differentiating between benign and malignant lesions and for predicting T stage, but is limited for predicting nodal status.

Domestic violence: legal, practice, and educational issues

Domestic violence is a recognized and growing public health concern in the United States. Health care professionals have a duty to improve the identification of victims of domestic violence, intervene effectively, and advocate for better education to break the cycle of abuse.

Endoscopic ultrasound for peripancreatic masses

BACKGROUND

Pancreatic neoplasms can be difficult to diagnose and stage preoperatively. Accurate staging allows the surgeon to select which patients can benefit from resection versus palliative therapy. Endoscopic ultrasound (EUS) with endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a diagnostic modality that provides visualization of peripancreatic tumors and their relationship to the surrounding structures as well as enabling cytologic diagnosis of the tumor and adjacent lymphadenopathy.

METHODS

To define the role of this technique, a retrospective study was performed on 20 patients in the past year with peripancreatic tumors.

RESULTS

Twelve men and 8 women ranging in age from 28 to 84 years (mean 67) were included in the study. Each patient underwent computed tomography followed by EUS-FNA, and the results were compared with operative findings or clinical course. The EUS-FNA findings included 10 pancreatic ductal carcinomas (50%), 5 pancreatitis (25%), 2 spindle cell neoplasms (10%), 1 cholangiocarcinoma (5%), 1 cystadenoma (5%), and 1 metastatic breast carcinoma (5%). Overall, EUS-FNA led to a significant change in the management of 12 patients (60%) through either diagnosing benign pathology, upstaging of the carcinoma, or determination that the peripancreatic mass represented a metastatic lesion. Five patients underwent resection of their peripancreatic tumors, and 3 patients had palliative procedures. Operative findings corresponded with EUS-FNA in all 8 patients. The 5 patients diagnosed with pancreatitis continued to be followed up for the possibility of a false negative FNA, but to date none have developed malignancy.

CONCLUSIONS

EUS-FNA is a useful tool for the imaging and staging of peripancreatic tumors and will aid in the proper preoperative selection of patients who will benefit from resectional therapy.

Clinical utility of endoscopic ultrasound-guided fine needle aspiration

OBJECTIVE

To assess our institution's initial experience with the clinical utility of endoscopic ultrasound (EUS)-guided fine needle aspiration.

STUDY DESIGN

Prospective analysis of the clinical utility of EUS-guided FNA.

RESULTS

Fifty-three patients underwent EUS-guided FNA of 64 sites, 28 for pancreatic masses, 15 for lymph nodes, 10 for solid lesions, 7 for cystic masses, 2 for submucosal masses and 2 for perigastrointestinal fluid. A cytopathologist was present during all procedures. An average of four passes (range, one to nine) was required to make a diagnosis in the 22 patients with pancreatic malignancies. There was one possible complication among the 53 patients. In 36 of the 53 patients, the combination of diagnostic EUS findings and cytologic diagnosis made a major change in the patient's management.

CONCLUSION

Because of its ability to affect patient management, EUS-guided FNA will become a more commonly used procedure, especially at oncologic centers. Since the number of fine needle passes needed for diagnosis is quite variable, it is important to have a cytopathologist participate in these procedures.

Endoscopic ultrasonography: a new diagnostic imaging modality

Endoscopic ultrasonography uses high-frequency ultrasound to visualize the gut wall and the surrounding structures of the mediastinum, the abdomen and the pelvis. Echoendoscopes are available in two different designs. A radial scanning echoendoscope produces a 360 degree real-time view perpendicular to the shaft of the echoendoscope. A linear-array instrument produces a 100 degrees real-time view parallel to the shaft of the echoendoscope, permitting direct ultrasonographic guidance of fine needles exiting the biopsy channel. Endoscopic ultrasonography has been established as the preferred diagnostic tool for the evaluation of submucosal masses of the upper gastrointestinal tract and the rectosigmoid, for differentiating benign from pathologic thickened gastric folds and for locating pancreatic endocrine tumors. The widest application of endoscopic ultrasonography is in the diagnosis and staging of esophageal, gastric, rectal and pancreaticobiliary neoplasms. Endosonography is the most accurate modality available for determining the T and N stages of these tumors. The recent development of endoscopic ultrasound-guided fine-needle aspiration provides physicians with the ability to cytologically diagnose lesions visualized endosonographically and to confirm cancer staging with tissue.

The clinical utility of endoscopic ultrasound-guided fine-needle aspiration in the diagnosis and staging of pancreatic carcinoma

BACKGROUND

Endoscopic ultrasound (EUS) guided fine-needle aspiration (FNA) of pancreatic lesions is being increasingly used. Our aim was to determine the safety, accuracy, and clinical utility of EUS-guided FNA in both the diagnosis and staging of pancreatic cancer.

METHODS

Forty-four patients (24 men/20 women) had EUS-guided FNA of pancreatic lesions (39 head/neck, 5 body, 3 tail) and/or associated lymph nodes. The mean age was 61 (range, 28 to 88 years). The indication for EUS-guided FNA was a pancreatic lesion seen initially on CT (39%), ERCP (43%), or EUS (18%). Follow-up data were collected on all patients for mean of 14.5 months (range 1 to 33 months).

RESULTS

CT detected only 15 of 61 (25%) focal lesions seen by EUS, Adequate specimens were obtained by EUS-guided FNA in 44 of 47 (94%) pancreatic lesions and 14 of 14 (100%) associated lymph nodes (overall adequacy was 95%). Of the 46 lesions in which specimens were adequate and a final diagnosis was available (32 malignant, 14 benign), EUS-guided FNA had a sensitivity of 92%, specificity of 100%, and diagnostic accuracy of 95% for pancreatic lesions and 83%, 100%, and 88% for lymph nodes, respectively. Six percent of pancreatic cases had inadequate specimens and, if included, lowered the sensitivity to 83%, specificity to 80%, and diagnostic accuracy to 88% for pancreatic lesions. In 3 patients with enlarged celiac nodes on EUS, EUS-guided FNA was able to make a tissue diagnosis of metastasis, which changed the preoperative staging and precluded surgery. EUS in combination with EUS-guided FNA precluded surgery in 12 of 44 (27%) and may have precluded surgery in an additional 6 of 44 (14%). EUS-guided FNA avoided the need for further diagnostic tests, thus expediting therapy in a total of 25 (57%) patients and influenced clinical decisions in 30 of 44 (68%) patients. The estimated cost savings based on surgeries avoided was approximately $3300 per patient. There was only one complication (2%), a post-FNA fever.

CONCLUSION

EUS-guided FNA of the pancreas appears to be a safe and effective method that increases both the diagnostic and staging capability of EUS in pancreatic cancer. The clinical impact of EUS-guided FNA includes avoiding surgery and additional imaging studies with a substantial cost savings.

Endoscopic ultrasound (EUS) and EUS-guided fine-needle aspiration of the left adrenal gland

BACKGROUND

We reported the application of endoscopic ultrasound (EUS) and EUS-guided fine-needle aspiration (FNA) in the local staging of lung cancer. Up to 16% of patients with lung cancer may have adrenal masses. The role of EUS in the characterization of the adrenal gland, as well as EUS-guided FNA of the adrenal gland, has not been described.

METHODS

The adrenal gland was characterized by EUS in 30 of 31 (97%) patients. EUS-guided FNA of an adrenal was performed in one patient. Anatomic correlation and ex vivo images were obtained.

RESULTS

The average dimension was 2.5 cm (range 1.4 to 3.5) x 0.8 cm (range 0.3 to 1.4) with two morphologic types: "seagull" and "elliptical." One patient with lung cancer and a left adrenal mass with a nondiagnostic CT-guided FNA underwent EUS-guided FNA, which established the diagnosis of metastatic adenocarcinoma. Surgery was avoided.

CONCLUSIONS

The left adrenal can be imaged by EUS in almost all patients. EUS-guided FNA may be useful when applied to left adrenal metastatic tumors for tissue diagnosis.

A primer on linear array endosonographic anatomy

Linear array endosonography, with its capacity to perform EUS-guided FNA and EUS-guided injections, as well as color mapping and Doppler ultrasonography, is becoming an important instrument for the endosonographer. Familiarity with linear array anatomy, as introduced here, is the critical foundation on which these diagnostic and therapeutic procedures can be performed safely and effectively.

The role of endoscopic retrograde cholangiopancreatography in patients with laparoscopic cholecystectomies

BACKGROUND & AIMS

The best clinical strategy for using endoscopic retrograde cholangiopancreatography (ERCP) with laparoscopic cholecystectomy is unknown. The aim of this study is to use decision analysis to assess four different approaches to using ERCP in patients undergoing laparoscopic cholecystectomy.

METHODS

Decision trees were designed for four clinical strategies: (1) preoperative ERCP, with sphincterotomy for choledocholithiasis; (2) selective preoperative ERCP for patients at high risk for choledocholithiasis, choledocholithiasis found at surgery treated by postoperative ERCP; (3) no preoperative ERCP, choledocholithiasis detected intraoperatively treated by postoperative ERCP; and (4) no preoperative ERCP, choledocholithiasis detected intraoperatively treated with open common bile duct exploration. Using decision analysis with literature-derived data, the impact on outcome parameters was calculated.

RESULTS

Postoperative ERCP resulted in the lowest cost, procedure numbers, and hospital and back-to-work days. With high preoperative likelihood of choledocholithiasis, selective preoperative ERCP was probably a clinically equivalent strategy. Sensitivity analysis supported these conclusions when the probabilities and utilities were varied over a wide range. The open operative approach to choledocholithiasis was only favored if ERCP had < 75% diagnostic and < 50% therapeutic success rates or lengthened hospitalization by > 7 days.

CONCLUSIONS

This study suggests that performing ERCP after laparoscopic cholecystectomy minimizes costs and morbidity; however, when choledocholithiasis is likely, selective preoperative ERCP may be a clinically equivalent strategy.

The role of endoscopic retrograde cholangiopancreatography in patients with laparoscopic cholecystectomies

BACKGROUND & AIMS

The best clinical strategy for using endoscopic retrograde cholangiopancreatography (ERCP) with laparoscopic cholecystectomy is unknown. The aim of this study is to use decision analysis to assess four different approaches to using ERCP in patients undergoing laparoscopic cholecystectomy.

METHODS

Decision trees were designed for four clinical strategies: (1) preoperative ERCP, with sphincterotomy for choledocholithiasis; (2) selective preoperative ERCP for patients at high risk for choledocholithiasis, choledocholithiasis found at surgery treated by postoperative ERCP; (3) no preoperative ERCP, choledocholithiasis detected intraoperatively treated by postoperative ERCP; and (4) no preoperative ERCP, choledocholithiasis detected intraoperatively treated with open common bile duct exploration. Using decision analysis with literature-derived data, the impact on outcome parameters was calculated.

RESULTS

Postoperative ERCP resulted in the lowest cost, procedure numbers, and hospital and back-to-work days. With high preoperative likelihood of choledocholithiasis, selective preoperative ERCP was probably a clinically equivalent strategy. Sensitivity analysis supported these conclusions when the probabilities and utilities were varied over a wide range. The open operative approach to choledocholithiasis was only favored if ERCP had < 75% diagnostic and < 50% therapeutic success rates or lengthened hospitalization by > 7 days.

CONCLUSIONS

This study suggests that performing ERCP after laparoscopic cholecystectomy minimizes costs and morbidity; however, when choledocholithiasis is likely, selective preoperative ERCP may be a clinically equivalent strategy.

Mechanism of colonic permeation of inulin: is rat colon more permeable than small intestine?

BACKGROUND/AIMS

Colonic epithelium is considered to be relatively tight. The colonic "pore" diameter is 6 A; therefore, colonic epithelium has generally been considered to be impermeable to hydrophilic probes with a cross-sectional diameter of > 6 A. This study examined whether rat colon is permeable to inulin, a large hydrophilic macromolecule having a molecular weight of 5000 g/mol and a cross-sectional diameter of 15 A (hydration diameter, 20 A).

METHODS

The colonic permeation of inulin (10 mumol/L) in vivo was investigated by perfusion of rat colonic segments.

RESULTS

There was significant colonic permeation of inulin, but tissue retention of inulin was low. The net colonic flux of inulin was strongly dependent on net water flux, showing a strong solvent drag effect. Addition of 16,16-dimethyl prostaglandin E2 decreased water flux with a corresponding decrease in inulin flux; this process seemed to be mediated by 5'-cyclic adenosine monophosphate because both the phosphodiesterase inhibitor aminophylline and dibutyryl adenosine 5'-cyclic adenosine monophosphate decreased water and inulin flux in a parallel manner. Chenodeoxycholic and taurocholic acids decreased net mucosal-to-serosal water flux but increased inulin flux. The net colonic permeation rate of inulin was higher than the small intestinal permeation rate.

CONCLUSIONS

Rat colon is permeable to inulin. The higher net colonic permeability may be caused by differences in mucosal surface, permselectivity, solvent drag effect, and differences in net water fluxes of the colon and small intestine.

Endoscopic ultrasound-guided fine needle aspiration of pancreatic carcinoma

Endoscopic ultrasound (EUS) is reported to be the single best modality for visualizing small pancreatic carcinomas. Whereas tissue diagnosis by fine needle aspiration (FNA) can be performed with computed tomography (CT) or transabdominal ultrasound guidance, the diagnostic accuracy is limited by the ability of these modalities to visualize the lesion. Real time EUS-guided fine needle aspiration has recently been reported as a new diagnostic modality. The application of EUS-guided FNA in the diagnosis of small pancreatic carcinoma has not been reported. We present a case in which transduodenal EUS-guided FNA was successful in establishing a definitive tissue diagnosis of pancreatic carcinoma in a 1.6-cm lesion in the head of the pancreas. This case along with a review of the literature highlights the great potential of this new modality in the diagnosis of pancreatic carcinoma.

Effect of difluoromethylornithine (DFMO) on NSAID-induced intestinal injury in rats

Combination therapy with difluoromethylornithine (DFMO) and a nonsteroidal antiinflammatory drug (NSAID) has been proposed for the chemoprevention of colonic neoplasia. The purpose of this study was to examine whether DFMO would affect NSAID-mediated intestinal injury. Male Sprague-Dawley rats were gavaged with 20 mg/kg of indomethacin, after seven days of exposure to drinking water with or without 2% DFMO. The rats were killed 24 or 48 hr later, and the small intestine removed for macroscopic and microscopic quantitation of intestinal injury by computerized image analysis. Seven days of DFMO alone had no effect on overall mucosal thickness, but did increase the depth of proximal intestinal crypts. Forty-eight hours after indomethacin, DFMO treatment decreased the number of indomethacin-induced ulcers and percent of the surface area ulcerated. However, DFMO also decreased the mucosal thickness, villus height, and crypt depth in indomethacin-treated rats. Thus although DFMO decreases macroscopic intestinal ulceration by indomethacin, the reduction in villus and crypt height suggests that it also impairs the mucosa's ability to recover from microscopic indomethacin-induced damage. This study shows DFMO does impact NSAID-mediated intestinal injury and therefore human trials with combinations of DFMO and NSAIDs should include monitoring for small intestinal injury.

Chronic omeprazole treatment increases duodenal susceptibility to ethanol injury in rats

To test whether omeprazole would increase the susceptibility of the duodenum to damage, 200 to 250-g male Sprague-Dawley rats were given 10 mg/kg of omeprazole (Losec) by gavage every morning for 29 days. Control rats were given gavage buffer alone. After fasting overnight, half the rats received 10 mg/kg indomethacin intraperitoneally; then all rats were given 2 ml of 50% ethanol by gavage. Three hours later the rats were killed and the stomach and duodenum removed and histologic injury to the duodenal mucosal was quantitated. In omeprazole pretreated rats, gavage with ethanol resulted in a significant twofold worsening of duodenal injury. Pretreatment with indomethacin to decrease endogenous prostaglandin production resulted in more severe ethanol-induced duodenal injury in both groups; however, there were no longer statistically significant differences between the omeprazole and control groups. Measurement of duodenal mucosal synthesis of prostaglandin E2 showed no difference between the omeprazole and control groups. Thus chronic administration of omeprazole appears to increase the susceptibility of the duodenal mucosa to ethanol injury in rats. The mechanism of this effect is as yet unknown but does not appear to be prostaglandin-mediated.

Per-rectal pulsed irrigation versus per-oral colonic lavage for colonoscopy preparation: a randomized, controlled trial

The aim of this study was to compare the efficacy and patient tolerance of a new pulsed irrigation system to colonic lavage for colonoscopic preparation. Thirty-four prospective patients scheduled for routine colonoscopy were randomized to one of two preparations: a per-rectal pulsed irrigation device (18 patients) versus per-oral colonic lavage (15 patients). Colonoscopic preparation was assessed on a 0 to 4 plus scale by region and overall. This was done live and by video tape by two independent endoscopists who were blinded to the patient's preparation. There was no significant difference with respect to cleanliness of the colon with pulsed irrigation patients having an average overall preparation score of 3.00 +/- 0.19 (SEM) versus colonic lavage patients with a score of 3.14 +/- 0.19. There was also no statistically significant difference between the two groups with respect to demographics, time to reach the cecum, time for entire procedure, volume of aspiration or wash, or sedation given. We conclude that the new pulsed irrigation device provides an alternative to the standard per-oral lavage solution for colonoscopic preparation.

Is the small intestinal epithelium truly "tight" to inulin permeation?

In this study, we evaluated the "leakiness" of intestinal epithelium through examination of small intestinal absorption of inulin in vivo by perfusing rat jejunum with 10 microM inulin. In physiological conditions, we found significant absorption of inulin at a rate of 44.6 nmol.100 cm-1.h-1 or absorption of 14.7%.100 cm-1.h-1 of the amount perfused. Increasing water flux by changing the luminal osmolarity resulted in linear (y = 31.1 + 2.4x, r = 0.97) increase in absorption of inulin, indicating a significant convective component of inulin absorption. There was large permeation of inulin at net water secretion and at zero net water fluxes (31.1 nmol.100 cm-1.h-1), indicating significant absorption of inulin by diffusive movement as well. The small intestinal tissue retention of inulin occurred rapidly within the first 15 min of perfusion, and the total tissue retention remained unchanged thereafter at approximately 10.8 nmol/100 cm. 16,16-Dimethylprostaglandin E2 decreased water flux, whereas cyclooxygenase inhibitors, indomethacin and acetylsalicylate, increased water flux. Inulin absorption closely paralleled changes in water flux induced by these agents. Taurocholate also caused parallel decrease in water and inulin absorption. Varying the resistance of unstirred water layer with changing luminal flow rate, the addition of mucolytic agent acetylcysteine, or alterations of luminal pH did not affect water or inulin absorption. We conclude that inulin permeates the small intestinal epithelium in significant amounts under normal physiological conditions, presumably through the paracellular pathways utilizing aqueous channels.

The effect of portal hypertension on indomethacin-induced small intestinal ulceration in the rat

The purpose of this study was to determine whether portal hypertension potentiates intestinal ulceration induced by indomethacin. Portal hypertension was produced in male Sprague-Dawley rats by two-staged ligation of the portal vein. Sham-operated rats were used as controls. The rats were given 20 mg/kg of indomethacin intragastrically, 7 and 14 days, respectively, after complete portal vein ligation. Forty-eight and 72 h after indomethacin, portal pressures were measured and the whole small intestine removed for quantitative measurement of the percent of the mucosa ulcerated by computerized image analysis. There were no differences in the area of ulceration between the portal hypertensive and sham-operated rats at either 7 or 14 days, despite the presence of significant portal hypertension. Portal hypertension does not appear to potentiate small intestinal ulceration induced by indomethacin in rats.

16,16-Dimethyl prostaglandin E2 induces villus contraction in rats without affecting intestinal restitution

In a previous study we found that 16,16-dimethyl prostaglandin E2 protects the small intestine against chenodeoxycholic acid injury in the rat. One possible explanation for prostaglandin's protective action may be that prostaglandin-induced villus contraction accelerates mucosal restitution. This hypothesis was tested in rats by perfusing intestinal segments in vivo in a single-pass fashion with 0.125-0.5 micrograms/L of 16,16-dimethyl prostaglandin E2. These studies showed a dose-dependent, reversible contraction of intestinal villi and crypts. To test the effect of this contraction on mucosal restitution, standardized intestinal injury was produced in indomethacin-pretreated rats perfused in vivo with 5 mmol/L chenodeoxycholic acid. The rats were then perfused with bile acid-free buffer containing either 0.5 microgram/mL of 16,16-dimethyl prostaglandin E2 or vehicle. This study showed that despite decreasing villus height after bile acid injury, 16,16-dimethyl prostaglandin E2 did not significantly affect the rate of morphologic (assessed by villus denudation) or functional (assessed by mannitol and water absorption) restitution of the injured intestinal mucosa. Thus, although 16,16-dimethyl prostaglandin E2 causes villus contraction, this effect does not result in more rapid restitution of the injured intestinal mucosa and is not a likely mechanism for prostaglandin-mediated protection of the intestinal mucosa.

Cimetidine reduces bile acid-mediated small intestinal mucosal injury in rats in vivo

Whether cimetidine has protective effects on the gastrointestinal mucosa independent of its ability to reduce gastric acid secretion is still controversial. To study this, rats had small intestinal mucosal injury induced in vivo by perfusion with 5 mM chenodeoxycholic acid. Control rats were compared to rats receiving either intraperitoneal or intravenous pretreatment with 50 mg/kg cimetidine or intraluminal pretreatment with 0.5 mM cimetidine. Mucosal injury was assessed by measuring villus tip epithelial cell denudation by computerized quantitative morphology. Intraperitoneal cimetidine reduced the average denudation/villus (micrometers) caused by 45-min perfusion with chenodeoxycholic acid: control = 39.1 +/- 7.7 (SEM), intraperitoneal cimetidine = 20.8 +/- 3.5 (P less than 0.05). Additionally, both intraluminal and intravenous cimetidine reduced villus denudation caused from 30 min perfusion with chenodeoxycholic acid: control = 62.5 +/- 5.8, intravenous cimetidine = 42.6 +/- 4.7 (P less than 0.05), intraluminal cimetidine = 44.6 +/- 7.2 (P less than 0.05). The observation that reduced mucosal injury is observed in an in vivo model that is independent of gastric acid supports the conclusion that cimetidine indeed has acid-independent protective properties.

Effect of portal hypertension on in vivo bile acid-mediated small intestinal mucosal injury in the rat

This study's purpose was to determine whether portal hypertension adversely affects small intestinal mucosal injury. Portal hypertension was produced in male Sprague-Dawley rats by two-stage ligation of the portal vein. Sham-operated rats were used as controls. Two weeks later, intestinal injury was produced by in vivo perfusion with 5 mM chenodeoxycholic acid for 30 min. Intestinal injury was assessed by quantitative morphometry and by measuring intestinal water and mannitol absorption. Portal hypertension resulted in more injury in the distal perfused intestine as manifested by increased villus tip denudation [portal hypertensive 52.5 +/- 9.6 (SEM) vs controls 28.1 +/- 5.7 microns, P = 0.05). Additionally there was a significant decrease in the unperfused duodenal villus height in portal hypertensive rats (portal hypertensive 755 +/- 22 vs controls 848 +/- 28 microns, P less than 0.02). Portal hypertension had no significant effect on the increase in mannitol absorption or water secretion caused by chenodeoxycholic acid perfusion. This study suggests that portal hypertension alters small intestinal mucosa and increases susceptibility to injury.

Intestinal morphometry and bile acid-induced mucosal injury in chronic experimental renal failure

To examine whether the intestinal mucosa in uremia is more prone to injury, we studied acute intestinal mucosal injury in rats with experimental chronic renal failure (RF) and sham-operated and starved control animals. Intestinal injury was produced by perfusing intestinal segments in vivo with 5 mmol/L chenodeoxycholic acid. Histologic specimens were then taken from the proximal and distal perfused and unperfused intestinal segments. Quantitative morphometry was done with computerized image analysis, and samples of the unperfused intestine were assayed for protein and DNA content. Chronic RF did not significantly affect the functional or morphologic injury caused by chenodeoxycholic acid. However, it was noted that RF rats had consistently taller villi and deeper crypts in all the samples studied. The protein content and the ratio of DNA to protein was similar among the three groups. The mechanism of the increase in villus height and crypt depth in the RF rats was not related to increases in tissue water content or to alterations in protein or DNA content, and the mechanism thus remains unexplained. This study clearly demonstrates, however, that the intestinal mucosa of rats with chronic renal insufficiency is not more susceptible to mucosal injury by bile acids than is the mucosa of appropriate control animals.

Effect of 16,16-dimethyl PGE2 and indomethacin on bile acid-induced intestinal injury and restitution in rats

Topically administered 16,16-dimethyl prostaglandin E2 reduced bile acid-induced small intestinal mucosal injury; however, the time course of restitution after such injury and whether either exogenous or endogenous prostaglandins affect this restitution are unknown. To explore these questions, mucosal injury was produced in 50 cm small intestinal segments of anesthetized male Sprague-Dawley rats perfused in vivo for 0, 5, 15, 30, or 45 minutes with buffer containing 5 mmol/L chenodeoxycholic acid, and to assess mucosal restitution, additional rats were perfused for 45 minutes with chenodeoxycholic acid followed by 15, 30, 60 or 120 minutes with chenodeoxycholate-free buffer. The above studies were then repeated in rats receiving either intraperitoneal indomethacin (10 mg/kg) or 15 minutes of preperfusion with buffer containing 1.4 mumol/L (0.5 microgram/ml) 16,16-dimethyl prostaglandin E2. Prostaglandin pretreatment reduced and indomethacin pretreatment increased significantly the morphologic (as measured by quantitative histology) and functional (as measured by mannitol and water absorption) mucosal injury caused by chenodeoxycholic acid. However, neither pretreatment had a major impact on the time course of functional or morphologic mucosal restitution, with nearly complete restitution occurring within 1 hour. Thus, although both endogenous and exogenous prostaglandins have a significant impact on bile acid-induced small intestinal mucosal injury, this effect is not caused by an acceleration of the rate of mucosal restitution.

Oral chenodeoxycholic acid increases small intestinal permeability to lactulose in humans

In animals, chenodeoxyholic acid (chenodiol) causes significant small intestinal mucosal injury which is paralleled by increased intestinal permeability. The objective of this study was to determine whether chenodiol increases small intestinal mucosal permeability in humans. This was assessed in a before-after trial by collecting urine from nine fasted healthy male volunteers for 3 h after oral intake of an isotonic solution containing 1 g mannitol, 5 g L-rhamnose and 10 g lactulose, all nondigestible sugars. After at least 72 h, this was repeated 1 h after taking 750 mg of chenodiol orally. The amount of each sugar excreted in the urine was quantified by high performance liquid chromatography. Chenodiol doubled the percent urinary excretion of lactulose from 0.21 +/- 0.12 (SD) to 0.42% +/- 0.25 (p less than 0.02) and the ratio of lactulose to mannitol or to rhamnose [0.012 +/- 0.005 to 0.027 +/- 0.013 (p less than 0.01) and 0.045 +/- 0.022 to 0.087 +/- 0.039 (p less than 0.05), respectively]. Oral administration of 750 mg chenodiol is associated with increased small intestinal permeability to lactulose in humans, supporting the possibility that this drug may also cause acute small intestinal mucosal injury.

Impact of endoscopy on mortality from occult cancer in radiographically benign gastric ulcers. A probability analysis model

Endoscopy is commonly used in the management of patients with radiographically benign gastric ulcers to detect occult malignancy. Clinical studies examining the cost-effectiveness of using endoscopy in such patients, however, have not been done. To address this issue using probability analysis, a probability tree was designed incorporating the possible clinical courses of patients with radiographically benign gastric ulcers managed with and without endoscopy, and probability estimates for each course were derived by compiling data from the literature. Probability and sensitivity analysis was used to compare the impact on overall mortality rate and cost-effectiveness of six commonly practiced methods of using endoscopy to manage patients with radiographically benign gastric ulcers: (1) all follow-up by upper gastrointestinal x-ray only; (2) endoscopy for nonhealing ulcers only; (3) endoscopy for all ulcers before medical therapy with all follow-up by upper gastrointestinal x-ray; (4) endoscopy for all ulcers after an initial trial of medical therapy; (5) endoscopy for all ulcers before therapy and for nonhealers; (6) endoscopy before therapy, and all follow-up by endoscopy. This analysis predicts that the greatest decrease in mortality rate occurs when endoscopy is used before medical therapy and for all follow-up, reducing the estimated number of deaths per 1000 patients with radiographically benign gastric ulcers from 36.7 with follow-up by upper gastrointestinal x-ray only to 27.2. However, initial endoscopy with all subsequent follow-up by upper gastrointestinal x-ray increased the overall death rate by only a small amount, to 28.0, and was consistently the most cost-effective method, requiring 116 endoscopies and approximately 60,000 diagnostic dollars per additional 5-yr survivor.

16,16-Dimethyl prostaglandin E2 reduced chenodeoxycholate-induced small intestinal mucosal injury in the rat

To determine whether prostaglandin may protect the small intestinal mucosa against bile acid-induced injury, we perfused in vivo rat jejunal segments with 5 mmol/L chenodeoxycholate with and without topical pretreatment with 2.6 mumol/L (1 microgram/ml) 16,16-dimethyl prostaglandin E2. Mucosal injury by chenodeoxycholate and its time sequence was assessed by using mannitol absorption and quantitative histology after 5, 15, 30, and 45 minutes of chenodeoxycholate perfusion. Forty-five-minute perfusion with chenodeoxycholate increased mannitol absorption from 0 to 0.9 nmol/min/cm, whereas prostaglandin pretreatment reduced this increase threefold (P less than 0.001). The increase in mannitol absorption coincided with progressive denudation of epithelial cells from intestinal villi. After 45 minutes exposure to chenodeoxycholate, an average of 50 micron of the cross-sectional surface of the villi tips was denuded of epithelial cells compared with only 25 micron denuded with prostaglandin pretreatment (P less than 0.01). These data indicate that topical administration of 16,16-dimethyl prostaglandin E2 reduces both the functional and morphologic small intestinal mucosal injury caused by chenodeoxycholate.

An assessment of the effect of "DOC talk" on school children in rural Iowa

The effectiveness of family physicians as health educators through a community health organization (Doctors Ought To Care/DOC) was studied. Seventh-grade students in a rural school system received a series of uniquely prepared slide presentations (DOC talks) on smoking, alcohol, drug use, and venereal disease to study the effect of such talks on knowledge gain and behavior change. The presentations were made during the semester in which the students were also taking a required health education course. A second group of seventh graders in the same school system did not receive the presentations but had the same health education course and served as the control group. Both groups showed similar gains in knowledge during their semester of health education. However, only the group which received the DOC talks showed a continuation of knowledge gains on a follow-up questionnaire. Also, only the group which saw the presentations showed positive behavior changes including decreased substance use. While aware of the study's methodologic limitations, we believe the results support the value of the community physician presenting DOC talks to supplement the usual school health curriculum.

Why have controlled trials failed to demonstrate a benefit of esophagogastroduodenoscopy in acute upper gastrointestinal bleeding? A probability model analysis

Numerous prospective randomized trials have failed to demonstrate a benefit attributable to early diagnostic esophagogastroduodenoscopy (EGD) in acute upper gastrointestinal bleeding (UGIB). The clinical implications of these studies have received extensive editorial comment and analysis. We have employed a probability model to further analyze the reasons why these studies have failed to demonstrate an impact of EGD on UGIB. The clinical course of each bleeding lesion can be predicted from the literature. For each lesion, the mortality associated with early specific intervention afforded by an early specific diagnosis can be compared with the mortality of intervention delayed by applying EGD only to those patients who have a complicated course marked by continued bleeding or rebleeding. Using optimistic assumptions that would tend to overstate the impact of EGD, this analysis estimates the maximum decrease in overall mortality in any of these trials afforded by early diagnostic EGD to be 1.2% which would require randomization of over 5000 patients to demonstrate this benefit in a prospective trial.

Relative effects of raster scan lines and image subtense on symbol legibility on television

This experiment examined the relative effects of (1) image size and (2) number of TV raster lines making up the image upon an observer's ability to identify 16 different geometric symbols on TV. Four raster-line values per symbol height were each tested at three image angular subtenses. Eight subjects were told to identify 25 symbols for each of the 12 conditions; all had 20/12 near and far visual acuity or better. The forced-choice method was used; no limits were placed on response times. The results showed that (1) at least eight raster lines per symbol height and (2) a symbol subtense of 10' of arc are necessary to obtain good symbol legibility on TV. An equation is developed from these and other data which quantifies the tradeoff between line number and angular subtense for different levels of performance.