Liquid Nitrogen Spray Cryotherapy is Associated With Less Postprocedural Pain Than Radiofrequency Ablation in Barrett's Esophagus: A Multicenter Prospective Study

GOALS AND BACKGROUND

Two common endoscopic therapies for eradication of dysplastic Barrett's esophagus are radiofrequency ablation (RFA) and liquid nitrogen spray cryotherapy (LNC). There is no data comparing postprocedural pain. This study aimed to compare the incidence of postprocedural pain between the 2 ablation modalities.

METHODS

This is a multicenter prospective study in which pain intensity scores and the presence of dysphagia were assessed immediately before and after treatment, 48 hours posttreatment and at 3 weeks posttreatment using validated instruments.

RESULTS

Of 94 patients, 35 underwent LNC and 59 underwent RFA [36 with focal radiofrequency ablation (RFA-F) and 23 with circumferential radiofrequency ablation (RFA-C)]. Immediately posttreatment, patients in the LNC group reported an average Numeric Pain Scale score that was lower than in the RFA groups [LNC 0.41 vs. RFA-F 1.18 (P=0.026), LNC 0.41 vs. RFA-C 1.38 (P=0.010)]. These differences persisted at 48 hours posttreatment [LNC 0.76 vs. RFA-F 1.77 (P=0.013), LNC 0.76 vs. RFA-C 1.73 (P=0.018)]. The odds of pain after RFA were at least 5 times greater than after LNC [immediately posttreatment odds ratio, 5.26 (95% confidence interval, 1.85-14.29) and 48 h posttreatment odds ratio, 5.56 (95% confidence interval, 2.27-14.29)]. There was no difference in dysphagia after treatment in either group, at any time point (P=0.429).

CONCLUSION

LNC was associated with less postprocedural pain when compared with RFA. These results help inform patients and physicians about the expected symptoms after ablative endotherapy.

Performance characteristics of optical coherence tomography in assessment of Barrett's esophagus and esophageal cancer: systematic review

Optical coherence tomography (OCT) can generate high-resolution images of the esophagus that allows cross-sectional visualization of esophageal wall layers. We conducted a systematic review to assess the utility of OCT for diagnosing of esophageal intestinal metaplasia (IM; Barrett's esophagus BE)), dysplasia, cancer and staging of early esophageal cancer. English language human observational studies and clinical trials published in PubMed and Embase were included if they assessed any of the following: (i) in-vivo features and accuracy of OCT at diagnosing esophageal IM, sub-squamous intestinal metaplasia (SSIM), dysplasia, or cancer, and (ii) accuracy of OCT in staging esophageal cancer. Twenty-one of the 2,068 retrieved citations met inclusion criteria. In the two prospective studies that assessed accuracy of OCT at identifying IM, sensitivity was 81%-97%, and specificity was 57%-92%. In the two prospective studies that assessed accuracy of OCT at identifying dysplasia and early cancer, sensitivity was 68%-83%, and specificity was 75%-82%. Observational studies described significant variability in the ability of OCT to accurately identify SSIM. Two prospective studies that compared the accuracy of OCT at staging early squamous cell carcinoma to histologic resection specimens reported accuracy of >90%. Risk of bias and applicability concerns was rated as low among the prospective studies using the QUADAS-2 questionnaire. OCT may identify intestinal metaplasia and dysplasia, but its accuracy may not meet recommended thresholds to replace 4-quadrant biopsies in clinical practice. OCT may be more accurate than EUS at staging early esophageal cancer, but randomized trials and cost-effective analyses are lacking.

Endoscopic spray cryotherapy for esophageal cancer: safety and efficacy

BACKGROUND

Few options exist for patients with localized esophageal cancer ineligible for conventional therapies. Endoscopic spray cryotherapy with low-pressure liquid nitrogen has demonstrated efficacy in this setting in early studies.

OBJECTIVE

To assess the safety and efficacy of cryotherapy in esophageal carcinoma.

DESIGN

Multicenter, retrospective cohort study.

SETTING

Ten academic and community medical centers between 2006 and 2009.

PATIENTS

Subjects with esophageal carcinoma in whom conventional therapy failed and those who refused or were ineligible for conventional therapy.

INTERVENTIONS

Cryotherapy with follow-up biopsies. Treatment was complete when tumor eradication was confirmed by biopsy or when treatment was halted because of tumor progression, patient preference, or comorbid condition.

MAIN OUTCOME MEASUREMENTS

Complete eradication of luminal cancer and adverse events.

RESULTS

Seventy-nine subjects (median age 76 years, 81% male, 94% with adenocarcinoma) were treated. Tumor stage included T1-60, T2-16, and T3/4-3. Mean tumor length was 4.0 cm (range 1-15 cm). Previous treatment including endoscopic resection, photodynamic therapy, esophagectomy, chemotherapy, and radiation therapy failed in 53 subjects (67%). Forty-nine completed treatment. Complete response of intraluminal disease was seen in 31 of 49 subjects (61.2%), including 18 of 24 (75%) with mucosal cancer. Mean (standard deviation) length of follow-up after treatment was 10.6 (8.4) months overall and 11.5 (2.8) months for T1 disease. No serious adverse events were reported. Benign stricture developed in 10 (13%), with esophageal narrowing from previous endoscopic resection, radiotherapy, or photodynamic therapy noted in 9 of 10 subjects.

LIMITATIONS

Retrospective study design, short follow-up.

CONCLUSIONS

Spray cryotherapy is safe and well tolerated for esophageal cancer. Short-term results suggest that it is effective in those who could not receive conventional treatment, especially for those with mucosal cancer.

Safety and efficacy of endoscopic spray cryotherapy for Barrett's esophagus with high-grade dysplasia

BACKGROUND

Endoscopic ablation to treat Barrett's esophagus (BE) with high-grade dysplasia (HGD) is associated with a decreased incidence of esophageal adenocarcinoma. Endoscopic spray cryotherapy (CRYO) demonstrates promising preliminary data.

OBJECTIVE

To assess the safety and efficacy of CRYO in BE with HGD.

DESIGN

Multicenter, retrospective cohort study.

SETTING

Nine academic and community centers; treatment period, 2007 to 2009.

PATIENTS

Subjects with HGD confirmed by 2 pathologists. Previous EMR was allowed if residual HGD remained.

INTERVENTIONS

CRYO with follow-up biopsies.

MAIN OUTCOME MEASUREMENTS

Complete eradication of HGD with persistent low-grade dysplasia, complete eradication of all dysplasia with persistent nondysplastic intestinal metaplasia, and complete eradication of all intestinal metaplasia.

RESULTS

Ninety-eight subjects (mean age 65.4 years, 83% male) with BE and HGD (mean length 5.3 cm) underwent 333 treatments (mean 3.4 treatments per subject). There were no esophageal perforations. Strictures developed in 3 subjects. Two subjects reported severe chest pain managed with oral narcotics. One subject was hospitalized for bright red blood per rectum. Sixty subjects had completed all planned CRYO treatments and were included in the efficacy analysis. Fifty-eight subjects (97%) had complete eradication of HGD, 52 (87%) had complete eradication of all dysplasia with persistent nondysplastic intestinal metaplasia, and 34 (57%) had complete eradication of all intestinal metaplasia. Subsquamous BE was found in 2 subjects (3%).

LIMITATIONS

Nonrandomized, retrospective study with no control group, short follow-up (10.5 months), lack of centralized pathology, and use of surrogate outcome for decreased cancer risk.

CONCLUSIONS

CRYO is a safe and well-tolerated therapy for BE and HGD. Short-term results suggest that CRYO is highly effective in eradicating HGD.

Recurrent flares of pancreatitis predict development of exocrine insufficiency in chronic pancreatitis

BACKGROUND & AIMS

The natural history of specific morphologic stages of chronic pancreatitis (CP) is not well defined. The aim of this study was to determine if worsening morphologic stages of CP are associated with poorer clinical outcomes.

METHODS

A retrospective analysis of 159 subjects with CP was performed. The baseline stage of CP was categorized according to the Cambridge classification. Pain was categorized as type A (intermittent acute), B (continuous), or combined. Exocrine failure was defined by steatorrhea; endocrine failure was characterized as diabetes mellitus. Complications were defined clinically.

RESULTS

Pancreatic duct (PD) morphology was equivocal in 37.1%, minimal in 12.6%, moderate in 7.5%, and severe in 42.8% of the patients. Over a median follow-up period of 3.7 years, the risk of developing exocrine insufficiency and diabetes was 28% and 19%, respectively. Recurrent acute flares of pancreatitis predicted the development of exocrine insufficiency (P = .004). Severe PD morphology predicted the likelihood of having persistent pain (P = .008). Patients with concurrent type A and B pain and older age at diagnosis had a greater likelihood of having persistent pain (P = .021). The risk of developing bile duct stricture was higher in the advanced morphologic stages of CP (P = .005).

CONCLUSIONS

Recurrent flares of pancreatitis predispose to the development of exocrine insufficiency in CP. Patients with complex-type pain, older age at diagnosis, and advanced morphologic stage are more likely to have persistent pain. PD morphology does not correlate with the risk of developing exocrine failure and/or diabetes. Pain does not necessarily decrease or disappear with the onset of exocrine insufficiency and diabetes.

Acute phosphate nephropathy--an emerging issue

Acute phosphate nephropathy is an accepted complication of the use of phosphate preparations in patients about to undergo colonoscopy. Age, renal failure, and the ongoing use of medications, such as angiotensin-converting enzyme inhibitors and/or angiotensin-receptor blockers, are now recognized as risk factors for the development of phosphate nephropathy. The presence of any of these risk factors necessitates careful attention to avoiding excessive dehydration in the process of bowel cleansing. In so doing, the likelihood of acute phosphate nephropathy occurring can be lessened.

Endoscopic ultrasound-guided (neurolytic) celiac plexus block

Celiac plexus neurolysis is an established technique for relieving pain in cancers of the upper abdomen. This article reviews the novel technique of endoscopic ultrasound (EUS)-guided neurolytic celiac plexus block. This recently described procedure is a therapeutic extension of curvilinear array endosonographic fine needle aspiration. The indications, patient preparation, and technical aspects of the procedure are described in detail. The potential complications are mentioned and the results of the published studies are reviewed. We believe that where the expertise is available, this procedure can be integrated into the diagnostic EUS of patients with inoperable upper abdominal malignancy. As such, this would be the safest and most cost-effective approach for celiac plexus neurolysis in these patients. The role of EUS-guided celiac plexus block in patients with chronic pancreatitis may be emerging and needs further study.

Recurrent Acute Pancreatitis Caused by a Gastric Duplication Communicating with an Aberrant Pancreas

A 24-year-old female patient who had suffered from recurrent bouts of acute pancreatitis for over 3 years was found on endoscopic retrograde cholangiopancreatography to have an aberrant pancreatic duct that terminated in a cyst. An aberrant lobe of pancreas had been discovered at exploratory laparotomy 3 years previously and was left untreated. Excision of the aberrant lobe of pancreas and accompanying gastric duplication cyst was curative. This case illustrates the importance of obtaining endoscopic retrograde cholangiopancreatography in all young individuals with recurrent pancreatitis to detect this rare, but curable, cause of pancreatitis.

Recurrent acute pancreatitis caused by a gastric duplication communicating with an aberrant pancreas

A 24-year-old female patient who had suffered from recurrent bouts of acute pancreatitis for over 3 years was found on endoscopic retrograde cholangiopancreatography to have an aberrant pancreatic duct that terminated in a cyst. An aberrant lobe of pancreas had been discovered at exploratory laparotomy 3 years previously and was left untreated. Excision of the aberrant lobe of pancreas and accompanying gastric duplication cyst was curative. This case illustrates the importance of obtaining endoscopic retrograde cholangiopancreatography in all young individuals with recurrent pancreatitis to detect this rare, but curable, cause of pancreatitis.

Half-Fourier RARE MR cholangiopancreatography: experience in 300 subjects

PURPOSE

To determine prospectively the clinical applications and diagnostic accuracy of half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) cholangiopancreatography (MRCP) in a large patient population.

MATERIALS AND METHODS

Breath-hold, heavily T2-weighted half-Fourier RARE MRCP was performed in 265 patients with suspected pancreaticobiliary disease and in 35 control patients without symptoms or signs referrable to the biliary tract or pancreatic duct. MRCP findings were correlated with those at direct cholangiography, pathologic examination, cross-sectional imaging, and clinical follow-up.

RESULTS

Diagnostic MRCP examinations were obtained in 299 (99.7%) subjects. MRCP yielded an accuracy of 100% in determining the presence of pancreaticobiliary disease, the presence and level of biliary obstruction, and obstruction due to bile duct calculi. The accuracy of MRCP and MR imaging in determining the presence and level of malignant obstruction was 98.2%. MRCP obviated endoscopic retrograde cholangiopancreatography (ERCP) by excluding choledocholithiasis in patients with acute pancreatitis (n = 13) and nonspecific abdominal pain (n = 82). In patients with sclerosing cholangitis and acquired immunodeficiency syndrome cholangiopathy, MRCP depicted the biliary tract as clearly as did ERCP (n = 9). After failed ERCP, MRCP delineated the pancreaticobiliary tract and helped determine therapeutic options (n = 27).

CONCLUSION

Half-Fourier RARE MRCP enables accurate evaluation of pancreaticobiliary disease and obviates ERCP in some patients.

Magnetic resonance cholangiopancreatography: a new technique for evaluating the biliary tract and pancreatic duct

Magnetic resonance cholangiopancreatography (MRCP) represents a new development in MR technology that provides a noninvasive accurate means of evaluating the biliary tree and pancreatic duct. Recent technical refinements that allow for imaging of the entire biliary tree and pancreatic duct in 18 seconds make this examination easily performed even in critically ill patients. The clinical applications of MRCP are illustrated in a variety of scenarios that include choledocholithiasis, malignant obstruction, incomplete/failed endoscopic retrograde cholangiopancreatographies (ERCPs), postsurgical alterations of the biliary tract and gastrointestinal tract such as biliary-enteric anastomoses, intrahepatic bile duct pathology such as sclerosing cholangitis and AIDS cholangiopathy, chronic pancreatitis, congenital anomalies of the biliary tract and pancreatic duct, and gallbladder pathology.

Laparoscopic Nissen fundoplication for severe gastroesophageal reflux disease: pros and cons

The advent of the laparoscopic approach to Nissen fundoplication has led to a resurgence in enthusiasm for the surgical treatment of gastroesophageal reflux disease (GERD). However, controversy exists as to which subgroups of GERD patients are best treated surgically. The relative success of treatment with medical and surgical intervention in terms of both symptom control and objective resolution of esophageal injury must be weighed against the relative costs of each therapeutic strategy in both the short and long term, given that GERD tends to be a lifelong disorder. The following is the transcribed text of a debate held at the Medical College of Virginia as part of a continuing medical education program in which the statement "Laparoscopic antireflux surgery is superior to medical treatment for severe gastroesophageal reflux disease" was contested. Representatives from the departments of surgery and gastroenterology provided arguments supporting their respective sides of this issue. The purpose was not to promote polarization in treatment selection, but to review the available data in a forum that could promote development of a rational algorithm for clinical decision-making in patients with GERD who might benefit from antireflux surgery. Final comments from the authors are provided in an attempt to synthesize the arguments into a reasonable strategy for individual case management.

Small flat adenoma: important in colon carcinogenesis?

The risk for development of colonic carcinoma increases with increasing size of the polyp. Endoscopists have focused attention on large polyps. Small flat adenomas are sessile polyps that measure less than 1 cm; they are nearly flat, and they have a slight depression in the center. They have a high incidence of cancer in situ. Adenomatous polyps follow the adenoma-carcinoma sequence. Small flat adenomas do not appear to follow this sequence, but they may be precursors of so called de novo colonic carcinoma. The genetics of small flat adenomas are not fully elucidated. Small flat adenomas may not be identified during standard colonoscopy due to the small size of the lesion. Chromoendoscopy may increase the rate of detection.

Gallstone pancreatitis: an update

Gallstone pancreatitis is one of the more prevalent causes of pancreatitis. It accounts for more than two thirds of the cases of acute pancreatitis worldwide and 25 to 45% of the cases in the United States. Furthermore, it is one of the most important treatable causes of pancreatitis. These two important features of the disease make its recognition and proper management critical. Key to recognition and proper management of gallstone pancreatitis is understanding that this disease can exist in three different forms. It can exist as impacted gallstone pancreatitis, as nonimpacted gallstone pancreatitis, or as sludge-related pancreatitis. Each of these forms of the disease will have some unique features relating to their pathogenesis, diagnosis, and treatment. This update focuses on "take-home" features that will allow (1) clinical differentiation between the three forms of the disease and (2) understanding the unique features that relate to their pathogenesis, diagnosis, and management.

Nonsteroidal antiinflammatory drug-induced gastroduodenal lesions: prophylaxis and treatment

Nonsteroidal antiinflammatory drugs (NSAIDs) are one of the most commonly prescribed agents, especially for elderly patients. These drugs frequently produce mucosal petechiae and erosions in the stomach and duodenum, but these conditions are rarely of clinical significance. NSAIDs, however, cause considerable morbidity and mortality due to their ability to cause gastric and duodenal ulcers. NSAID-induced ulcers are most likely to develop in elderly women receiving multiple NSAIDs for prolonged periods. NSAIDs injure gastric and duodenal mucosa by both a topical and a systemic effect. The latter is responsible for the pathogenesis of NSAID-associated ulcers. These ulcers are particularly prone to perforation and hemorrhage. Both complications frequently occur in asymptomatic long-term users of NSAIDs. H2 antagonists prevent NSAID-related duodenal ulcers but are not effective for prevention of gastric ulcers. Misoprostol is the only agent proven to decrease the risk of gastric ulcers in patients receiving NSAIDs. Both H2 antagonists and omeprazole are highly effective for the treatment of established duodenal ulcers in patients receiving NSAIDs. H2 antagonists also heal gastric ulcers in these patients but at slower rates than in patients not receiving NSAIDs. The existing literature is reviewed, and guidelines for prophylaxis against NSAID-induced ulcers and treatment of established ulcers are provided.

Pharmacological control of gastric acid secretion

Gastric acid produced by the parietal cells has a significant role in a variety of gastrointestinal diseases, such as duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease. We address acid production by the parietal cell and the pharmacological means to control gastric acid secretion. The physiology of parietal cell acid secretion is reviewed. The role of acid-suppressive therapy with histamine H2 antagonists and omeprazole in duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease is discussed. Pharmacology, side-effect profile, and dosage requirements of the histamine H2 antagonists and omeprazole are outlined.

Stapled ileoanal anastomosis for ulcerative colitis and familial polyposis without a temporary diverting ileostomy

Between March 1989 and August 1990, we performed 21 stapled J pouch ileonal procedures (20 ulcerative colitis [UC], 1 familial polyposis [FP]) without an ileostomy in 19, of whom 13 were taking prednisone and eight underwent semi-emergent surgery for uncontrollable bleeding. During the same time, an additional four patients required a standard ileonal procedure. The results of anal manometry and clinical function were compared to 25 patients who had previously undergone mucosal stripping and a sutured J pouch ileoanal anastomoses with a temporary diverting ileostomy between October 1982 and August 1990. During this same time period, an additional 19 patients underwent an anti-peristaltic reversed J pouch and 18 an S pouch, for a total of 83 ileoanal procedures. The reversed J pouch had a lower stool frequency than a standard J pouch but had an unacceptable incidence of complications and problems with pouch emptying. The S pouch had a stool frequency similar to the standard J pouch but provided greater length in patients with a short mesentery. Stapled J pouch ileoanal patients had a better (p less than 0.02) maximum and sphincter resting pressure (46 +/- 11 versus 34 +/- 12 mmHg), fewer (p less than 0.05) night-time accidents (22% versus 68%), daytime (17% versus 55%) or night-time (28 versus 61%) spotting, or use of a protective pad at night (11% versus 42%) than nonstapled J pouch ileoanal patients. Stool frequency was similar in the two groups. All but one UC patient had residual disease at the anastomosis. Anal mucosa between the dentate line and stapled anastomosis was 1.8 +/- 1.3 cm (range, 0 to 3.5 cm). Complications in the nonstapled J pouch group included 4 pouches excised (2 for complications, 2 for excessive stool frequency), 1 pelvic abscess, 2 stenosis requiring dilation under anesthesia, 1 enterocutaneous fistula after ileostomy closure, 1 ileostomy site hernia, and 2 small bowel obstructions. Of the 65 patients who underwent ileostomy closure in the entire series, 8 (12%) developed a complication requiring surgical intervention. Complications in the stapled group included 1 anastomotic leak, 1 pouch leak, and 1 pelvic abscess. Patients were managed successfully with drainage (all 3) and diverting ileostomy (1). One patient developed stenosis requiring dilation under anesthesia. The stapled J pouch ileoanal anastomosis is a simpler, safer procedure with less tension than a standard handsewn J pouch but leaves a very small cuff of residual disease. It provides significantly better stool control and may obviate the need for an ileostomy with its complications.

A prospective assessment of the Garren-Edwards Gastric Bubble and bariatric surgery in the treatment of morbid obesity

Morbid obesity is a serious medical hazard, and effective alternatives to surgery have been unsuccessful. In 1985, the Garren-Edwards Gastric Bubble (GEGB) was offered as an adjunct to dietary and behavioral therapy for weight loss treatment. The safety and efficacy of the GEGB were compared with bariatric surgery, the current standard for the treatment of morbid obesity. Fifty-seven patients received GEGB and 77 underwent bariatric surgery. GEGB patients were divided into two groups: those who attended group therapy and those who did not. This study showed that bariatric surgery was far more effective in reducing excess body weight during a 12-month period compared with the GEGB plus group therapy and the GEGB alone. The morbidity from bariatric surgery was greater than in the GEGB-treated groups, while the cost for uncomplicated cases for a year's treatment was comparable. It is concluded that the GEGB does not offer an effective alternative to bariatric surgery in the treatment of morbid obesity.

Small intestinal motility: normal and abnormal function

This review outlines the properties and function of intestinal smooth muscle and the mechanisms that underlie contraction and relaxation. Both tonic and phasic (rhythmic) contraction are mediated by an increase in intracellular calcium. Phasic contraction is paced electrically by rhythmic changes in membrane potential (slow waves) which, upon reaching a threshold, lead to opening of membrane calcium channels and the entry of calcium into muscle cells; this inwardly directed calcium current or spike initiates a cascade of events resulting in contraction. Slow waves and spike potentials and, thus, phasic contraction, are influenced by neurotransmitters, hormones, and drugs. In circular muscle, these agents can also increase calcium by releasing it from intracellular stores, thus inducing tonic contraction. Ingestion of food initiates peristaltic propulsive activity which, in its rhythm, is superimposed on spontaneous phasic activity. The peristaltic reflex consists of two successive phases: relation of circular muscle distal to the distending bolus (descending relaxation) and contraction proximal to the bolus (ascending contraction). In-between meals, a different, slower pattern of muscle activity prevails, known as the migrating motor complex, which helps to maintain the lumen of the intestine free of contents. Improved understanding of normal muscle function is beginning to reflect itself in improved management of patients with motility disorders.

Colorectal cancer. A blueprint for disease control through screening by primary care physicians

The Virginia Colorectal Cancer Control Project is a statewide effort to reduce morbidity and mortality from colorectal cancer by stimulating the adoption of screening and early detection practices by primary care physicians. The project emphasizes use of the three-day fecal occult blood test, digital rectal examination, and endoscopy. Recruitment strategies included personal contact, newsletters, journal articles, and screening workshops. Of the 33 318 patients screened over 26 months, positive fecal occult blood test reactions were recorded in 3.3% of asymptomatic patients and in 14.8% of symptomatic patients. Polyps were found in 149 and cancer was diagnosed in 94 patients of whom one third were asymptomatic. Eighty percent of the latter had Dukes' A and B lesions, 12% had Dukes' C lesions, and 8% had Dukes' D lesions. In contrast, only 36% of the symptomatic cancers were Dukes' A and B lesions, and 69% were Dukes' C and D lesions. These results suggest that primary care physicians can be effective in the screening and detection of precancerous polyps and early-staged colorectal cancers.

Prevention of acute gastrointestinal complications after severe head injury: a controlled trial of cimetidine prophylaxis

Cimetidine prophylaxis significantly reduced the risk of gastrointestinal bleeding after severe head injury in this prospective, double-blind clinical trial. Cimetidine effectively reduced both the volume and the acidity of gastric secretions after brain injury without producing adverse side effects. The most common endoscopic finding was superficial, erosive, mucosal lesions in the proximal stomach. Cimetidine prophylaxis was not shown to reduce the incidence of these lesions in this study but did diminish their severity and the likelihood that they would complicate the management of these patients.

Interaction of acetylcholine and cholecystokinin with dispersed smooth muscle cells

Isolated gastric smooth muscle cells were prepared from the stomach of Bufo marinus by successive incubation in collagenase without added trypsin. Contraction was determined by image-splitting micrometry and expressed as the mean percentage decrease in cell length from control. Peak contractile response was attained within 30 s. Dose-response curves constructed from peak responses showed that the maximal responses to CCK-OP (37.2 +/- 3.8%), acetylcholine (35.3 +/- 2.5%), and Ca2+ (42.3 +/- 0.9%) were similar. The D50s for octapeptide of cholecystokinin (CCK-OP) and acetylcholine were around 10(-12) M and 10(-11) M, respectively. The response to a combination of submaximal concentrations of acetylcholine and CCK-OP exceeded the individual responses but did not exceed the maximal response to either agent alone. A low concentration of atropine (5 X 10(-10) M) inhibited specifically the maximal response to acetylcholine. A high concentration of atropine (5 X 10(-8) M) inhibited partially the maximal response to CCK-OP but had no effect on the maximal response to Ca2+. It was concluded that 1) dispersed gastric smooth muscle cells are highly sensitive to stimulation; 2) CCK-OP has a direct (myogenic) contractile effect on gastric smooth muscle; and 3) the effect of CCK-OP and acetylcholine are mediated by separate receptors.

Binding of secretin to plastic surfaces

Five carboxyl-terminal fragments of secretin ranging in size from 6 to 21 amino acid residues were tested for pancreatic secretory activity in the rat. None of the fragments displayed activity when given alone but each displayed significant activity when given after secretin. This apparent activity was shown to be the result of displacement of secretin bound to the walls of the injection catheter. The activity was abolished by dissolving secretin in 2% bovine serum albumin. The finding emphasizes the ease with which secretin can bind to plastic surfaces and consequently the need to reevaluate previous dose-response studies and the caution required in the design of future studies.

Gastric and esophageal dysfunction after ingestion of acid

Esophageal and gastric function was measured in a patient who swallowed a household acid solution. Dysphagia, transient ulceration of the esophagus with luminal narrowing, and complete loss of peristalsis without loss of lower esophageal sphincter function were noted. Gastric dysfunction appeared 2 weeks after ingestion with complete obstruction, necessitating antral resection. The proximal stomach was relatively spared.

Inhibition of VIP-stimulated intestinal secretion and cyclic AMP production by somatostatin in the rat

The effect of somatostatin on colonic secretion induced by 10(-8) M vasoactive intestinal peptide (VIP), 10(-2) M theophylline, and 2 X 10(-3) M dibutyryl cyclic AMP was studied in muscle-stripped everted open rat colon sacs. The secretory response to VIP, measured as the decrease in net absorptive flow rate (microliters 30 min-1 mg-1 of dry weight), was maximal and equalled the responses to theophylline or dibutyryl cyclic AMP. Somatostatin (10(-5) M) blocked completely the secretory response to VIP but only partially the secretory response to theophylline or dibutyryl cyclic AMP. This difference in the extent of inhibition suggested that somatostatin exerted an inhibitory effect both before and after the point of generation of intracellular cyclic AMP. In order to test the hypothesis that one component of the action of somatostatin involved inhibition of the production of cyclic AMP, measurements of this nucleotide were made in isolated rat colon cells. Control levels of cyclic AMP measured by radioimmunoassay (12.6 +/- 1.6 pmoles per 10(6) cells) were not affected by 10(-5) M somatostatin. VIP (5 X 10(-8) M) increased cyclic AMP levels 2-fold (P less than 0.01) and this increase was blocked by somatostatin. The results indicated that somatostatin inhibits colonic secretion by exerting effects at two sites: one site lies at, and another beyond, the point of generation of intracellular cyclic AMP.

Comparative effects of synthetic and natural vasoactive intestinal peptide on pancreatic and biliary secretion and on glucose and insulin blood levels in the dog

The effects of synetic porcine vasoactive intestinal peptide (VIP) on pancreatic and biliary secretion and on glucose, insulin and calcium blood levels were examined in the dog and compared with the effects of natural porcine VIP. Synthetic VIP was a secretin-like partial agonist of pancreatic and biliary secretion with efficacies relative to secretin of 0.27 and 0.41, respectively. Consistent with its weak secretin-like action, synthetic VIP augmented the pancreatic response to CCK-OP and the submaximal but not the maximal response to secretin. Synthetic VIP also produced a dose-dependent increase in blood glucose levels and a synchronous and proportionate increase in blood insulin levels. A slight increase in total calcium levels was equivocal. The effects of antural VIP on pancreatic and biliary secretion and on glucose and insulin blood levels were identical to those of synthetic VIP. The identity of effects supports the validity of the postulated structure of porcine VIP. Although elicited at high doses, the effects of VIP on exocrine and endocrine secretion may be relevant physiologically in the context of a neurocrine or paracrine role for VIP.

Mediation of guinea pig gastric secretion in vitro by cyclic nucleotides

The effect of methacholine, theophylline, and cyclic adenyl and guanyl nucleotides on gastric secretion from antral and proximal duodenal mucosa of the guinea pig was studied. Both 2 mM dibutyryl (db) cAMP and 5 mM theophylline produced significant increases in gastrin secretion, 4.3 +/- 0.7 (P less than 0.001) and 9.3 +/- 2.4 pg mg-1 min-1 (P less than 0.005) respectively, above basal gastrin secretion (1.5 +/- 0.4 pg mg-1 min-1). The combined effect of the two agents was additive (14.5 +/- 3.6 pg mg-1 min-1). Db cGMP (2 mM) had no effect on gastrin secretion. Methacholine produced a dose-related increase in gastrin secretion which at maximum equaled the combined effect of theophylline and db cAMP. The results suggest that gastrin secretion is mediated in part by intracellular cAMP but do not exclude a cooperative involvement of cGMP.

Stimulatory (H1) and inhibitory (H2) histamine receptors in gallbladder muscle

The nature of histamine receptors in gallbladder muscle and examined using specific histamine-receptor agonists and antagonists. The H2-receptor antagonist, metiamide, augmented the contractile response to histamine indicating that gallbladder muscle possessed stimulatory H1 receptors and inhibitory H2 receptors. The independent inhibitory character of H2 receptors was confirmed by (1) induction of relaxation with histamine after H1-receptor blockade and the suppression of this relaxation with metiamide, and (2) induction of relaxation with a specific H2-receptor agonist, 4-methyl histamine and the suppression of this relaxation with metiamide. Further, blockade of H2 but not of H1 receptors augmented the response to the octapeptide of cholecystokinin. The nature of this effect was such that the apparent affinity of the octapeptide for its own receptor was increased. The finding raised the possibility that in their native unoccupied state, H2 receptors may modify the response to hormonal agents.

Clearance rate, half-life, and secretory potency of human gastrin-17-I in different species

The clearance rates of synthetic human gastrin-17-I were measured in man, dog, and cat. Half-life of disappearance and acid secretory potency (D50) were also measured in man and dog. The clearance rates in dog and cat were, respectively, 3 and 8 times more than in man. Accordingly, the half-life of gastrin-17 in the dog (3.5 min) was 3 times shorter than in man (9.5 to 10.5 min). The D50 for acid secretion was proportional to the clearance rate and yielded approximately similar increments of serum gastrin, indicating an equal sensitivty to gastrin-17 at cellular level in the three species. An inverse allometric relation between clearance rate and body weight was consistent with the known greater efficiency of metabolic and eliminatory processes in species of small size. Recent studies of the disposal of other gastrointestinal hormones indicate that the concepts developed theoretically for secretory stimulants and confirmed experimentally for gastrin-17 may have wider applicability.