Adding Safety Rules to Surgeon-Authored Virtual Reality Training

INTRODUCTION

The Toolkit for Illustration of Procedures in Surgery (TIPS) is an open source virtual reality (VR) laparoscopic simulation-based training environment with force feedback. The TIPS-author is a content creation interface that allows a surgeon educator (SE) to assemble new laparoscopic training modules. New technology enables safety rules to be specified by the SE, automatically tracks specified safety errors, and summarizes and communicates achievements and errors to the surgical trainee.

METHODS

The TIPS-author combines and initializes building blocks of anatomy with their physical properties, as selected by the SE from a database. The SE can add any safety rule that can be tested in terms of location, proximity, separation, clip count, and force. Errors are then automatically monitored during simulation and recorded as visual snapshots for feedback to the trainee. The TIPS was field tested at 2 surgical conferences, one before and one after adding the error snapshot feature.

RESULTS

Sixty-four respondents at 2 surgical conferences assessed the utility of TIPS on a Likert scale. While other ratings remained unchanged for an overall score of 5.24 of 7 (7 = very useful), the rating of the statement "The TIPS interface helps learners understand the force necessary to explore the anatomy" improved from 5.04 to 5.35 of 7 after the snapshot mechanism was added.

CONCLUSIONS

The ratings indicate the viability of the TIPS open source SE-authored surgical training units with safety rules. Presenting SE-determined procedural missteps via the snapshot mechanism at the end of the training increases perceived utility.

Assessment of parental decision making in congenital heart disease, cardiomyopathy and heart transplantation: an observational study analysing decisional characteristics and preferences

OBJECTIVE

We explore shared decision making (DM) in guardians of children with heart disease by assessing the desired weight of influence on DM and factors that may alter the relative weight of parent or medical team influence.

METHODS

Guardians of patients <21 years and admitted >1 week in the paediatric cardiac intensive care unit (PCICU) were recruited. Twelve vignettes were designed including technical (antibiotic selection, intubation, peripherally inserted central catheter placement, ventricular assist device placement, heart transplant, organ rejection, heart rhythm abnormalities and resuscitation effort) and non-technical vignettes (cessation of life-sustaining therapies, depression treatment, obesity and palliative care referral). Participants responded to questions on DM characteristics and one question querying preference for relative weight of parent or medical team influence on DM.

RESULTS

Of 209 participants approached, 183 were included. Most responded with equal desire of medical team and parental influence on DM in all vignettes (range 41.0%-66.7%). Technical scenarios formed one cluster based on DM characteristics, compared with non-technical scenarios. Factors that increase the relative weight of parental influence on DM include desired input and involvement in big-picture goals (OR 0.274, CI [0.217 to 0.346]; OR 0.794, CI [0.640 to 0.986]). Factors that increase the relative weight of medical team influence on DM include perception of medical expertise needed (OR 1.949 [1.630 to 2.330]), urgency (OR 1.373 [1.138 to 1.658]), benefit (OR 1.415 [1.172 to 1.710]), number of PCICU admissions (OR 1.134 [1.024 to 1.256]) and private insurance (OR 1.921 [1.144 to 3.226]).

CONCLUSION

Although factors may alter the weight of influence on DM, most parents desire equal parental and medical team influence on DM.

Dental student perceptions of teamwork during a community-engaged interprofessional learning experience

INTRODUCTION

Dental professionals have been strong advocates for interprofessional education (IPE). During PFF, students in diverse, interprofessional teams of four are assigned a local volunteer family during their first academic year. Teams conduct four home visits and implement a health improvement project focused on the family's health and well-being. The purpose of our analysis was to examine dental student perspectives on the use of teamwork skills during this unique interprofessional educational experience.

METHODS AND MATERIALS

Dental student responses from 2017 to 2018 and 2018 to2019 were qualitatively analysed. Open coding by hand was used to identify keywords and themes. The themes and open codes were compared and contrasted by the researchers until a consensus was reached on themes.

RESULTS

Researchers discerned three meta-themes: value, skills and time. Researchers also found eight sub-themes prevalent in responses: teamwork, adaptability, mutual support, trust, interprofessional communication, time, feedback, coordination and accountability.

DISCUSSION

Our findings indicate dental students understood the importance of interprofessional teamwork and experiential learning within the context of PFF. Students communicated an understanding of how teamwork skills can impact team-oriented outcomes. Dental students seemed to value many teamwork skills that contributed to their interprofessional team's success and experiential learning experience.

CONCLUSION

Engagement in a longitudinal experience that is patient-centred, requiring time outside of the classroom, is valued by dental students for its interprofessional collaborative competency development.

Hospital homebound students and K-12 online schooling

The flexibility afforded by online education may provide opportunities for learners with disability who require absence from traditional learning environments. This study sought to describe how a subset of learners with disability, those with hospital-homebound designation, perform in K-12 online classes, particularly as compared to non-hospital homebound counterparts. A cross-sectional analysis was performed of all Florida Virtual School course enrollments from August 1, 2012 to July 31, 2018. Researchers analyzed 2,534 course enrollments associated with K-12 students who, at the time of their course enrollment, had hospital-homebound designation, and a comparison group of 5,470,591 enrollments from K-12 students without hospital-homebound status. Data analysis showed three important outcomes. First, hospital-homebound designated student academic performance was equivalent to their non-hospital homebound counterparts. Second, however, hospital-homebound course enrollments were 26% more likely to result in a withdrawal prior to grade generation. Third, these withdrawals were potentially mitigated when H/H designated students were enrolled in five or more classes or in classes with five or more students. The results of this study provided evidence that when they can remain enrolled, hospital-homebound learners experience equivalent academic outcomes in online learning environments. These findings suggest that healthcare professionals should be made aware of the potentially equivalent outcomes for their patients. Moreover, virtual schools should seek to identify and create supports for these students.

Using machine learning analysis to assist in differentiating between necrotizing enterocolitis and spontaneous intestinal perforation: A novel predictive analytic tool

PURPOSE

Necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) are devastating diseases in preterm neonates, often requiring surgical treatment. Previous studies evaluated outcomes in peritoneal drain placement versus laparotomy, but the accuracy of the presumptive diagnosis remains unknown without bowel visualization. Predictive analytics provide the opportunity to determine the etiology of perforation and guide surgical decision making. The purpose of this investigation was to build and evaluate machine learning models to differentiate NEC and SIP.

METHODS

Neonates who underwent drain placement or laparotomy NEC or SIP were identified and grouped definitively via bowel visualization. Patient characteristics were analyzed using machine learning methodologies, which were optimized through areas under the receiver operating characteristic curve (AUROC). The model was further evaluated using a validation cohort.

RESULTS

40 patients were identified. A random forest model achieved 98% AUROC while a ridge logistic regression model reached 92% AUROC in differentiating diseases. When applying the trained random forest model to the validation cohort, outcomes were correctly predicted.

CONCLUSIONS

This study supports the feasibility of using a novel machine learning model to differentiate between NEC and SIP prior to any intended surgical interventions.

LEVEL OF EVIDENCE

level II TYPE OF STUDY: Clinical Research Paper.

Design of a Situational Judgment Test for Preclinical Interprofessional Collaboration

PROBLEM

There is an unmet need for economically feasible, valid, reliable, and contextually relevant assessments of interprofessional collaborative knowledge and skills, particularly at the early stages of health professions education. This study sought to develop and gather content and internal structure validity for an Interprofessional Situational Judgement Test (IPSJT), a tool for the measurement of students' interprofessional collaborative intentions during the early stages of their professional development.

APPROACH

After engaging in an item development and refinement process (January-June 2018), an 18-question IPSJT was administered to 953 first-year students enrolled in 10 health professions degree programs at the University of Florida Health Science Center in October 2018. The IPSJT's performance was evaluated using item-level analyses, item difficulty, test-retest reliability, and exploratory factor analysis.

OUTCOMES

Seven hundred thirty-seven (77.3%) students consented to the use of their data. Student IPSJT scores ranged from 0 to 69, averaging 42.68 (standard deviation = 12.28), with some statistically significant differences in student performance by health professions degree program. IPSJT item difficulties ranged from 0.13 to 0.92. Once one item with poor properties was excluded from analysis, the IPSJT demonstrated an overall reliability of 0.62. Students were more successful at identifying the least effective than the most effective responses. Test-retest reliability provided evidence of consistency (r = 0.50, P < .001) and similar item difficulty across administrations. An exploratory factor analysis indicated a 3-factor model with multiple cross-factor loadings.

NEXT STEPS

This work represents the first step toward the development of a valid, reliable IPSJT for early learners. The emergent 3-factor model provides evidence that multiple competencies can be assessed in early learners via this tool. Additional research is necessary to build a more robust question bank, explore different scoring and response methods, and gather additional sources of validity evidence, including relations to other variables.

Using Data Mining for the Early Identification of Struggling Learners in Physician Assistant Education

PURPOSE

Despite the importance of early intervention and remediation, the relatively short duration of physician assistant education programs necessitates the importance of early identification of at-risk learners. This study sought to ascertain whether machine learning was more effective than logistic regression in predicting remediation status among students, using the limited set of data available before or immediately following the first semester of study as predictor variables and academic remediation as an outcome variable.

METHODS

The analysis included one institution and student data from 177 graduates between 2017 and 2019. We employed one data mining model, random forest trees, and compared it to a traditional predictive analysis method, logistic regression. Due to the small sample size, we employed leave-one-out cross-validation and bootstrap aggregation.

RESULTS

Data provided evidence that the random forest algorithm correctly identified individuals who would later experience academic intervention with a 63.3% positive predictive value, whereas logistic regression exhibited a positive predictive value of 16.6%.

CONCLUSIONS

This single-institution study indicates that predictive modeling, employing machine learning, may be a more effective means than traditional statistical methods of identifying and providing assistance to learners who may experience academic challenges.

Teaching Students How to Improve Safety and Quality in Two Children's Hospitals: Building a Pediatric Clerkship Patient Safety and Quality Experience

This report describes a novel method to enhance medical student understanding of systems-based practice and patient safety through experiential learning, assessing the perceived value of student-identified patient safety and systems vulnerabilities, and their proposed interventions at academic children's hospitals.

Using Team-Based Learning in Interprofessional Education to Promote Content Knowledge and Team Skills Applications

Date Presented 4/18/2015

Team-based learning (TBL) was used to facilitate a longitudinal interprofessional experience (IPE) for 600 students across 10 professions. Content outcomes and teamwork evaluations provide evidence that TBL is an efficient means for facilitating IPE.

Pediatric residents' learning styles and temperaments and their relationships to standardized test scores

BACKGROUND

Board certification is an important professional qualification and a prerequisite for credentialing, and the Accreditation Council for Graduate Medical Education (ACGME) assesses board certification rates as a component of residency program effectiveness. To date, research has shown that preresidency measures, including National Board of Medical Examiners scores, Alpha Omega Alpha Honor Medical Society membership, or medical school grades poorly predict postresidency board examination scores. However, learning styles and temperament have been identified as factors that 5 affect test-taking performance. The purpose of this study is to characterize the learning styles and temperaments of pediatric residents and to evaluate their relationships to yearly in-service and postresidency board examination scores.

METHODS

This cross-sectional study analyzed the learning styles and temperaments of current and past pediatric residents by administration of 3 validated tools: the Kolb Learning Style Inventory, the Keirsey Temperament Sorter, and the Felder-Silverman Learning Style test. These results were compared with known, normative, general and medical population data and evaluated for correlation to in-service examination and postresidency board examination scores.

RESULTS

The predominant learning style for pediatric residents was converging 44% (33 of 75 residents) and the predominant temperament was guardian 61% (34 of 56 residents). The learning style and temperament distribution of the residents was significantly different from published population data (P  =  .002 and .04, respectively). Learning styles, with one exception, were found to be unrelated to standardized test scores.

CONCLUSIONS

The predominant learning style and temperament of pediatric residents is significantly different than that of the populations of general and medical trainees. However, learning styles and temperament do not predict outcomes on standardized in-service and board examinations in pediatric residents.

Family-centered rounds and medical student education: a qualitative examination of students' perceptions

BACKGROUND

Although current literature supports the benefits of family-centered rounds on medical education, few studies have explored students' perceptions of family-centered rounds.

PURPOSE

The aim of this study was to provide a better and broader understanding of the effect of family-centered rounds on medical student education.

METHODS

During the inpatient portion of the third-year pediatric clerkship at a southeastern United States 4-year medical school, students were exposed to family-centered and conference room work rounds and completed a post-hoc reflective open-ended questionnaire. The study was conducted from July to December 2007 and the inpatient experience was at one of two large academic medical centers. Using a constant comparative approach, the qualitative content of 45 of the 63 potential students' responses was analyzed.

RESULTS

Family-centered rounds served as an opportunity for medical students to build their practice-based knowledge through direct and simultaneous interaction with the medical team, patients, and families. Family member communication, medical team communication, and increased exposure to patients allowed for unique learning opportunities such as augmentation of communication skills, practice with use of lay terms, legitimate peripheral participation, and humanizing cognitive understanding of diseases. Areas of concern noted by the students included space limitations, length of rounds, potential anxiety provoked in the patient, and faculty and resident comfort with teaching certain topics.

CONCLUSIONS

Our qualitative analysis of medical student perceptions on family-centered rounds suggests that pediatric medical student education may benefit by improving knowledge and practice with communication and humanizing disease processes. However, perceived barriers, such as concerns about space or instructor comfort with teaching certain topics, existed. Further studies are warranted to gain a better understanding of the educational impact of conducting this type of rounds.

Nonclinical use of online social networking sites: new and old challenges to medical professionalism

The AMA Council on Ethical and Judicial Affairs (CEJA) has written a position paper on how social medical use challenges medical professionalism. The report offers persuasive ethical and practical guidelines for nonclinical internet use, specifically for social networking. This commentary provides a framework from which to apply these guidelines, but adds that there may be important situations in which physicians are not able to act in accordance. The guidelines call for professional reporting of questionable online portrayals or behaviors, but this commentary argues that this may be not only cumbersome to implement, but may violate aspects of constitutional rights. While online social networking may in many ways be a new application of old challenges, there may be other aspects that require novel approaches to medical professionalism.

Revisiting Social Network Utilization by Physicians-in-Training

OBJECTIVE

To measure and compare the frequency and content of online social networking among 2 cohorts of medical students and residents (2007 and 2009).

METHODS

Using the online social networking application Facebook, we evaluated social networking profiles for 2 cohorts of medical students (n  =  528) and residents (n  =  712) at the University of Florida in Gainesville. Objective measures included existence of a profile, whether it was made private, and whether any personally identifiable information was included. Subjective outcomes included photographic content, affiliated social groups, and personal information not generally disclosed in a doctor-patient encounter. We compared our results to our previously published and reported data from 2007.

RESULTS

Social networking continues to be common amongst physicians-in-training, with 39.8% of residents and 69.5% of medical students maintaining Facebook accounts. Residents' participation significantly increased (P < .01) when compared to the 2007 data. Individuals in the 2009 cohort had significantly more "friends" (P < .01), belonged to more "groups" (P < .01), and were more likely to limit public access to their profiles through the use of privacy settings (P < .01) than the individuals in the 2007 cohort.

DISCUSSION

Online social networking application use by physicians-in-training remains common. While most now limit access to their profiles, personal profiles that still allow public access exhibited a few instances of unprofessional behavior. Concerns remain related to the discovery of content in violation of patient privacy and the expansive and impersonal networks of online "friends" who may view profiles.

An analysis of healthcare providers' online ratings

BACKGROUND

Many websites allow consumers to evaluate their healthcare experience yet scant data exist that explore the type and content of reviews.

OBJECTIVE

To evaluate and describe online healthcare provider reviews.

METHODS

We analysed 16,703 ratings on 6101 providers from four US cities. Ratings spanned five categories and an overall provider score. We also performed text analyses of narrative commentary (n = 15,952).

RESULTS

Providers had a high mean score for each category (3.7-4.0 out of 5). Higher overall scores were associated with higher staff (adjusted odds ratio (aOR) 3.0, 95% CI 2.9-3.0, P < 0.01) and punctuality scores (aOR 2.1, 95% CI 2.05-2.15, P < 0.01). Review frequency was inversely associated with scores, (aOR 0.94, 95% CI 0.92-0.96, P < 0.01). Analyses of narrative commentaries revealed more positive than negative terms (P < 0.01).

CONCLUSIONS

Online ratings were largely positive. Future research must discern how online surveys affect patient referrals, provider reputations and patients' perceptions of quality of care.

Visual Analyses of the Creation of Avatars

Video games are becoming more popular; there has been a particular rise in interest and use of massively multiplayer online role-playing games (MMORPGs). These games utilize avatar creation; avatars can be seen as the technological instantiation of the real person in the virtual world. Little research has been conducted on avatar creation. Although it is has been anecdotally postulated that you can be anything you want online, there is a dearth of research on what happens when participants are told to create avatars, particularly avatars within given contexts. In this study, we used the Second Life avatar creation tool to examine what would happen when participants were told to create avatars as heroes, villains, their ideal self, and their actual self. Data analyses reveal that characters often refuse to change permanent aspects of their features, instead modifying only temporal aspects. This research has provided support for the quantitative review of avatar characteristics as predictors of vignette groupings.

The intersection of online social networking with medical professionalism

AIM

To measure the frequency and content of online social networking among medical students and residents.

METHODS

Using the online network Facebook, we evaluated online profiles of all medical students (n = 501) and residents (n = 312) at the University of Florida, Gainesville. Objective measures included the existence of a profile, whether it was made private, and any personally identifiable information. Subjective outcomes included photographic content, affiliated social groups, and personal information not generally disclosed in a doctor-patient encounter.

RESULTS

Social networking with Facebook is common among medical trainees, with 44.5% having an account. Medical students used it frequently (64.3%) and residents less frequently (12.8%, p < .0001). The majority of accounts (83.3%) listed at least 1 form of personally identifiable information, only a third (37.5%) were made private, and some accounts displayed potentially unprofessional material. There was a significant decline in utilization of Facebook as trainees approached medical or residency graduation (first year as referent, years 3 and 4, p < .05).

DISCUSSION

While social networking in medical trainees is common in the current culture of emerging professionals, a majority of users allow anyone to view their profile. With a significant proportion having subjectively inappropriate content, ACGME competencies in professionalism must include instruction on the intersection of personal and professional identities.

Maintenance of CNS tissues in vitro for subsequent pharmacologic evaluation: a simple and inexpensive superfusion chamber

A new simple, inexpensive holding chamber is described for maintaining brain slices in a viable condition for long periods of time. The advantages of its superfusion-type operation and application of this chamber to in vitro electrophysiologic studies of the pharmacologic action of serotonin in the midbrain dorsal raphe nucleus are discussed.

The ontogeny of [3H]5-hydroxytryptamine binding in the lamb: effects of in vivo thyroidectomy

The effects of congenital hypothyroidism in the late gestation ovine fetus include changes in serotonin concentrations in specific brain areas. To investigate possible ontogenic patterns of changes in 5-HT receptor function, we studied the binding characteristics of [3H]5-HT in the midbrain, hypothalamus and cerebral cortex in the late gestation ovine fetus and young lamb. We compared the binding characteristics of control fetuses to those of thyroidectomized fetuses, with or without thyroxine replacement therapy. In each of the areas examined, age-dependent changes in the receptor density (Bmax) for [3H]5-HT was observed. In cerebral cortex, Bmax was constant from 120 days gestation through the early neonatal period and increased significantly only at 25-30 days after birth. In hypothalamus, [3H]5-HT binding density decreased late in gestation (140-145 days) with a return after birth to values comparable to those at 120-125 and 130-135 days gestation. The midbrain also exhibited a significant age-dependent pattern of altered receptor density with a decrease in the 130-135 and 140-145 day gestational age groups compared to both younger and older lambs. In contrast, the affinity constant (Kd) for [3H]5-HT did not change over the ages evaluated in cerebral cortex or hypothalamus. In the midbrain, however, there was a significant increase in Kd at 1-5 days after birth compared to all other age groups. The ability of fetal thyroidectomy, with or without thyroxine replacement therapy, to alter patterns of [3H]5-HT binding was also tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging but not estrogen alters regional [3H]5-HT binding in the CNS of female Fischer 344 rats

Age-related changes in serotonergic regulation of neuroendocrine function were investigated in female Fischer 344 rats; serotonin ([3H]5-HT) binding sites were characterized in several brain regions. Neither the number (Bmax) nor the affinity (Kd) of [3H]5-HT sites were altered in the frontal cortex of reproductively young and senescent groups. However, a significant decline in receptor affinity was observed in the hypothalamus and midbrain dorsal raphe nucleus. An increase in the density of binding sites was also observed in the hypothalamus with advancing age. Acute 48 h exposure to estrogen failed to influence [3H]5-HT binding site characteristics in these brain regions. In summary, these results suggest that age-related changes in [3H]5-HT binding are regionally specific. Moreover, the observed changes in hypothalamic 5-HT function may underlie neuroendocrine aging events.

Fura 2 analysis of cytosolic calcium regulation in elutriated rat gastric parietal cells

The calcium probe, Fura 2, is used to establish and partially characterize histamine-, carbachol-, and forskolin-induced calcium transients in enriched parietal cell populations prepared by centrifugal elutriation of dispersed rat fundic mucosa cell isolates. The magnitude of the maximal carbachol response, which is blocked by atropine but not cimetidine, is nearly five times that of histamine or forskolin. Time to peak responses for carbachol, forskolin, and histamine are approximately 7, 17, and 28 sec, respectively. Carbachol-, histamine-, and forskolin-induced increases in Fura 2 fluorescence appear dependent upon extracellular calcium, since these responses are attenuated in low calcium media and blocked by EGTA in low-calcium media or by lanthanum in high- or low-calcium medium. Trifluoperazine and fenoctimine, at concentrations that inhibit secretion, have no effect on either carbachol- or histamine-induced increases in cytosolic calcium. Seven major calcium/EGTA-sensitive phosphoproteins are identified by SDS-PAGE electrophoresis of ATP 32P-labeled cell sonicates. We conclude that cytosolic calcium in enriched rat gastric parietal cell populations is regulated by secretagogue receptor-controlled calcium channels. We postulate that these channels may be controlled by cyclic AMP-dependent phosphorylation, since neither changes in cyclic AMP nor calcium alone mediate the effects of secretagogues entirely, but the interplay between these two second-messenger systems potentiates the actions of these agents. The role of cytosolic calcium as a second messenger in secretagogue action appears similar to that of cyclic AMP in that a specific cellular concentration must be reached to initiate acid secretion.

Inhibition of gastric acid secretion in vivo and in vitro by a new calmodulin antagonist, CGS 9343B

The new calmodulin antagonist, CGS-9343B, was found to inhibit both histamine plus 3-isobutyl-1-methylxanthine and carbachol-induced [14C]aminopyrine accumulation in dispersed, fundic mucosal cells of rats. The IC50 value for CGS-9343B inhibition of histamine plus 3-isobutyl-1-methylxanthine-induced [14C]aminopyrine accumulation was 306 nM. The drug was more potent than the H2-histamine receptor antagonist, cimetidine (1128 nM), less potent than the nonspecific calmodulin antagonists, trifluoperazine and fenoctimine (IC50 = 40 and 224 nM, respectively), and equipotent with the H+, K+-adenosine triphosphatase inhibitor, omeprazole (365 nM). CGS-9343B showed an IC50 of 369 nM for carbachol-induced [14C]aminopyrine accumulation in dispersed mucosal cells. CGS-9343B must be added to cells before or simultaneously with acid secretagogues in order to be effective. The drug did not reverse previously stimulated secretion. Unlike trifluoperazine and fenoctimine, CGS-9343B had anticamodulin activity for inhibition of calmodulin-activated (Type I) phosphodiesterase in the same range of potency as observed for the inhibition of aminopyrine accumulation. In anesthetized rats and dogs the i.v. infusion of CGS-9343B did not block histamine plus pentagastrin-stimulated acid secretion. However, i.a. administration of CGS-9343B to anesthetized rats produced a significant inhibition of acid secretion. In vivo the order of potency was omeprazole greater than cimetidine much greater than CGS-9343B. These data provide evidence for involvement of calmodulin in the acid secretory process and suggest that the pursuit of selective calmodulin antagonists such as CGS-9343B may prove useful for understanding the regulation of the hydrogen ion secretory process.

Relationships of secretagogue-induced cAMP accumulation and acid secretion in elutriated rat gastric parietal cells

Centrifugal elutriation was adapted and analyzed as a method to separate rat gastric parietal cells from other fundic mucosal cells. Elutriated parietal cell fractions provided sufficient purity by morphological criteria, and fluorescence activated cell sorting analyses, yield, reproducibility and maintenance of functional responses. These characteristics allowed the study and comparison of the kinetics of histamine, isoproterenol, and forskolin-induced cyclic AMP and 14C-amino-pyrine accumulations in the presence of 1-methyl-3-isobutyl xanthine (IBMX) in parietal-cell-rich and parietal-cell-poor fractions. All three acid secretagogues studied produced the same maximal rate of acid secretion as judged by 14C-aminopyrine accumulation. Each secretagogue action peaked at different times and had different accumulation kinetics. For each agonist, cyclic AMP accumulation preceded secretion. However, the rate, extent, and temporal changes of cyclic AMP accumulation were independent of aminopyrine accumulation. HPLC separation and drug inhibition studies of cyclic nucleotide phosphodiesterase activities indicated the presence of multiple, high affinity (Type IV), but not lower affinity (Types I and II), enzyme forms in gastric mucosal cells. IBMX did not distinguish between the two forms, but SQ 65442 and RO 20-1724 were selective inhibitors. Inhibition constants of IBMX for phosphodiesterase hydrolysis agreed closely with its EC50 for histamine-stimulated acid secretion (2-8 microM). Elutriated parietal cells maintained their responses to selective receptor antagonists in the micromolar concentration range.