Addressing the Mental Health of Nursing Students During the Pandemic: The Evaluation of a Needs Assessment by a College of Nursing Mental Health Task Force.

BACKGROUND: A Mental Health Task Force (MHTF) was developed in a large public college of nursing in the Southeastern United States to address the urgent mental health needs expressed by growing numbers of nursing students related to the coronavirus disease 2019 (COVID-19). AIMS: The purpose of this study was to report on a needs assessment conducted by the MHTF. METHODS: The needs assessment study design was a 16-item cross-sectional online survey and four "Town Hall" focus groups with nursing students, faculty, and staff (n = 1-8 participants per group). Survey data were analyzed using descriptive statistics and free-text questions from the survey and focus groups were analyzed using a qualitative descriptive approach. RESULTS: Undergraduate and graduate students (n = 115) ranging in age from 17 to 50 years completed the survey; 95% female, 94% full-time, 56% employed, 77% White, and 81% in the Bachelor of Science in Nursing program. Eleven students participated in the focus groups. The analysis of the free-text survey questions identified the students' perceived needs. Mental health care was the most frequently requested, followed by faculty check-ins, stress management, and peer support. CONCLUSIONS: The administration of the survey provided an opportunity for students to communicate concerns and make requests. To address the ongoing effects of the COVID-19 pandemic on nursing students, multi-modal needs assessments should be conducted periodically to identify priority mental health needs.

Emerging Concepts in Precision Medicine and Cardiovascular Diseases in Racial and Ethnic Minority Populations.

Cardiovascular diseases remain the leading cause of mortality and a major contributor to preventable deaths worldwide. The dominant modifiable risk factors and the social and environmental determinants that increase cardiovascular risk are known, and collectively, are as important in racial and ethnic minority populations as they are in majority populations. Their prevention and treatment remain the foundation for cardiovascular health promotion and disease prevention. Genetic and epigenetic factors are increasingly recognized as important contributors to cardiovascular risk and provide an opportunity for advancing precision cardiovascular medicine. In this review, we explore emerging concepts at the interface of precision medicine and cardiovascular disease in racial and ethnic minority populations. Important among these are the lack of racial and ethnic diversity in genomics studies and biorepositories; the resulting misclassification of benign variants as pathogenic in minorities; and the importance of ensuring ancestry-matched controls in variant interpretation. We address the relevance of epigenetics, pharmacogenomics, genetic testing and counseling, and their social and cultural implications. We also examine the potential impact of precision medicine on racial and ethnic disparities. The National Institutes of Health's All of Us Research Program and the National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine Initiative are presented as examples of research programs at the forefront of precision medicine and diversity to explore research implications in minorities. We conclude with an overview of implementation research challenges in precision medicine and the ethical implications in minority populations. Successful implementation of precision medicine in cardiovascular disease in minority populations will benefit from strategies that directly address diversity and inclusion in genomics research and go beyond race and ethnicity to explore ancestry-matched controls, as well as geographic, cultural, social, and environmental determinants of health.

Reducing Cardiovascular Disparities Through Community-Engaged Implementation Research: A National Heart, Lung, and Blood Institute Workshop Report.

Cardiovascular disparities remain pervasive in the United States. Unequal disease burden is evident among population groups based on sex, race, ethnicity, socioeconomic status, educational attainment, nativity, or geography. Despite the significant declines in cardiovascular disease mortality rates in all demographic groups during the last 50 years, large disparities remain by sex, race, ethnicity, and geography. Recent data from modeling studies, linked micromap plots, and small-area analyses also demonstrate prominent variation in cardiovascular disease mortality rates across states and counties, with an especially high disease burden in the southeastern United States and Appalachia. Despite these continued disparities, few large-scale intervention studies have been conducted in these high-burden populations to examine the feasibility of reducing or eliminating cardiovascular disparities. To address this challenge, on June 22 and 23, 2017, the National Heart, Lung, and Blood Institute convened experts from a broad range of biomedical, behavioral, environmental, implementation, and social science backgrounds to summarize the current state of knowledge of cardiovascular disease disparities and propose intervention strategies aligned with the National Heart, Lung, and Blood Institute mission. This report presents the themes, challenges, opportunities, available resources, and recommended actions discussed at the workshop.

Neighborhood Disadvantage, Poor Social Conditions, and Cardiovascular Disease Incidence Among African American Adults in the Jackson Heart Study.

OBJECTIVES: To examine the impact of neighborhood conditions resulting from racial residential segregation on cardiovascular disease (CVD) risk in a socioeconomically diverse African American sample. METHODS: The study included 4096 African American women (n = 2652) and men (n = 1444) aged 21 to 93 years from the Jackson Heart Study (Jackson, Mississippi; 2000-2011). We assessed neighborhood disadvantage with a composite measure of 8 indicators from the 2000 US Census. We assessed neighborhood-level social conditions, including social cohesion, violence, and disorder, with self-reported, validated scales. RESULTS: Among African American women, each standard deviation increase in neighborhood disadvantage was associated with a 25% increased risk of CVD after covariate adjustment (hazard ratio = 1.25; 95% confidence interval = 1.05, 1.49). Risk also increased as levels of neighborhood violence and physical disorder increased after covariate adjustment. We observed no statistically significant associations among African American men in adjusted models. CONCLUSIONS: Worse neighborhood economic and social conditions may contribute to increased risk of CVD among African American women. Policies directly addressing these issues may alleviate the burden of CVD in this group.

Capacity-Building for Career Paths in Public Health and Biomedical Research for Undergraduate Minority Students: A Jackson Heart Study Success Model.

OBJECTIVE: This article chronicles the building of individual student capacity as well as faculty and institutional capacity, within the context of a population-based, longitudinal study of African Americans and cardiovascular disease. The purpose of this article is to present preliminary data documenting the results of this approach. DESIGN: The JHS Scholars program is designed, under the organizational structure of the Natural Sciences Division at Tougaloo College, to provide solid preparation in quantitative skills through: good preparation in mathematics and the sciences; a high level of reading comprehension; hands-on learning experiences; and mentoring and counseling to sustain the motivation of the students to pursue further studies. SETTING: This program is on the campus of a private Historically Black College in Mississippi. PARTICIPANTS: The participants in the program are undergraduate students. MAIN OUTCOME MEASURES: Data, which included information on major area of study, institution attended, degrees earned and position in the workforce, were analyzed using STATA 14. RESULTS: Of 167 scholars, 46 are currently enrolled, while 118 have graduated. One half have completed graduate or professional programs, including; medicine, public health, pharmacy, nursing, and biomedical science; approximately one-fourth (25.4 %) are enrolled in graduate or professional programs; and nearly one tenth (9.3%) completed graduate degrees in law, education, business or English. CONCLUSIONS: These data could assist other institutions in understanding the career development process that helps underrepresented minority students in higher education to make career choices on a path toward public health, health professions, biomedical research, and related careers.

Research participants' opinions on genetic research and reasons for participation: a Jackson Heart Study focus group analysis.

The Jackson Heart Study (JHS) convened focus groups to engage the community in dialogue on participation in the National, Heart, Lung and Blood Institute's Candidate Gene Resource (CARe) project. CARe, a genome wide association and candidate gene study, required the release of participant phenotypic and genotypic data with storage at NIH for widespread distribution to qualified researchers. The authors wanted to assess the willingness of an African American community to participate in the genetics research, given the past history of bioethical misconduct in ethnic minority communities. The discussion produced the following specific issues of interest: reasons for participants' interest in genetics research; participants' knowledge about the JHS; and participants' knowledge about genetics research and its advantages and disadvantages. Training on genetic issues was also developed for the JHS community and staff.

Developing a research agenda for cardiovascular disease prevention in high-risk rural communities.

The National Institutes of Health convened a workshop to engage researchers and practitioners in dialogue on research issues viewed as either unique or of particular relevance to rural areas, key content areas needed to inform policy and practice in rural settings, and ways rural contexts may influence study design, implementation, assessment of outcomes, and dissemination. Our purpose was to develop a research agenda to address the disproportionate burden of cardiovascular disease (CVD) and related risk factors among populations living in rural areas. Complementary presentations used theoretical and methodological principles to describe research and practice examples from rural settings. Participants created a comprehensive CVD research agenda that identified themes and challenges, and provided 21 recommendations to guide research, practice, and programs in rural areas.

The Perspectives of Programme Staff and Recipients on the Acceptability and Benefits of the Ward-Based Outreach Teams in a South African Province.

The re-engineering of primary health care (PHC) called for the establishment of ward-based outreach teams as a reform strategy to bridge the gap between health facilities and communities. The Nkangala district established ward-based outreach teams in 2012. We used process evaluation to assess the acceptability of the outreach teams from the perspectives of those involved in the implementation as well as the clients who are the recipients of the outreach services in order to describe how the programme benefits the recipients, the staff, and the health system. Data were collected through interviews with multiple data sources. A thematic analysis was done using NVivo 11. The outreach programme is acceptable to the recipients and staff. The acceptability translated into measurable benefits for the recipients and the health system. Health benefits included increased access to services, support for treatment adherence, and linkages to various sector departments for social support. Since the inception of outreach teams, the district has recorded low utilisation of PHC services and improved priority indicators such as immunisation coverage, early antenatal bookings, treatment adherence, TB cure rates, and decreased default rates. The positive effects of the outreach teams on indicators underscore the need to roll the programme out to all sub-districts.

Barriers to the Implementation of the Ward-Based Outreach Team Program in Mpumalanga Province: Results From Process Evaluation.

BACKGROUND: South Africa adopted the ward-based outreach team (WBOT) program as one aspect of the three-stream approach to primary health care (PHC) re-engineering. PHC re-engineering seeks to modify the hospicentric and curative approach into a more preventive and promotive approach to improve health outcomes. There has not been an evaluation of the implementation of the WBOTs in Nkangala District since its inception in 2012. METHODS: A process evaluation approach using qualitative methods was used to examine and describe the contextual, organizational, health provider, and program-related barriers considered to affect the implementation of the WBOTs 3 sub-districts in one of the health districts in Mpumalanga Province, South Africa. The framework for this evaluation was informed by the logic model framework developed by the Center for Disease Control as well as the 3 domains of evaluation recommended by the Medical Research Council Guidance on process evaluation. Data were collected through in-depth interviews with multiple data sources directly involved in the implementation of the WBOTs. A thematic analysis was done using NVivo 11. RESULTS: The key critical barriers identified by the evaluation include the inadequate provision of resources, the lack of supervision, the heavy workload for outreach teams, the inadequate and irregular payment of stipends, threats to the safety of the CHWs, and the cultural beliefs and practices of the communities who are to receive the services. The lack of adequate financial resources was the main challenge, and will continue to pose a risk to the successful implementation of the WBOTs. CONCLUSIONS: Although the barriers are being reported as separate contextual factors, the internal and external contexts are interdependent, interact with one each other, and should not be considered in isolation. The need to improve stakeholder engagement on the WBOT program underscores the importance of the external context in the successful implementation of WBOTs.

Cost-effectiveness of Contemporary Statin Use Guidelines With or Without Coronary Artery Calcium Assessment in African American Individuals.

Importance: Clinical and economic consequences of statin treatment guidelines supplemented by targeted coronary artery calcium (CAC) assessment have not been evaluated in African American individuals, who are at increased risk for atherosclerotic cardiovascular disease and less likely than non-African American individuals to receive statin therapy. Objective: To evaluate the cost-effectiveness of the 2013 American College of Cardiology/American Heart Association (ACC/AHA) guideline without a recommendation for CAC assessment vs the 2018 ACC/AHA guideline recommendation for use of a non-0 CAC score measured on one occasion to target generic-formulation, moderate-intensity statin treatment in African American individuals at risk for atherosclerotic cardiovascular disease. Design, Setting, and Participants: A microsimulation model was designed to estimate life expectancy, quality of life, costs, and health outcomes over a lifetime horizon. African American-specific data from 472 participants in the Jackson Heart Study (JHS) at intermediate risk for atherosclerotic cardiovascular disease and other US population-specific data on individuals from published sources were used. Data analysis was conducted from November 11, 2018, to November 1, 2019. Main Outcomes and Measures: Lifetime costs and quality-adjusted life-years (QALYs), discounted at 3% annually. Results: In a model-based economic evaluation informed in part by follow-up data, the analysis was focused on 472 individuals in the JHS at intermediate risk for atherosclerotic cardiovascular disease; mean (SD) age was 63 (6.7) years. The sample included 243 women (51.5%) and 229 men (48.5%). Of these, 178 of 304 participants (58.6%) who underwent CAC assessment had a non-0 CAC score. In the base-case scenario, implementation of 2013 ACC/AHA guidelines without CAC assessment provided a greater quality-adjusted life expectancy (0.0027 QALY) at a higher cost ($428.97) compared with the 2018 ACC/AHA guideline strategy with CAC assessment, yielding an incremental cost-effectiveness ratio of $158 325/QALY, which is considered to represent low-value care by the ACC/AHA definition. The 2018 ACC/AHA guideline strategy with CAC assessment provided greater quality-adjusted life expectancy at a lower cost compared with the 2013 ACC/AHA guidelines without CAC assessment when there was a strong patient preference to avoid use of daily medication therapy. In probability sensitivity analyses, the 2018 ACC/AHA guideline strategy with CAC assessment was cost-effective compared with the 2013 ACC/AHA guidelines without CAC assessment in 76% of simulations at a willingness-to-pay value of $100 000/QALY when there was a preference to lose 2 weeks of perfect health to avoid 1 decade of daily therapy. Conclusions and Relevance: A CAC assessment-guided strategy for statin therapy appears to be cost-effective compared with initiating statin therapy in all African American individuals at intermediate risk for atherosclerotic cardiovascular disease and may provide greater quality-adjusted life expectancy at a lower cost than a non-CAC assessment-guided strategy when there is a strong patient preference to avoid the need for daily medication. Coronary artery calcium testing may play a role in shared decision-making regarding statin use.

Similar deficiencies in procedural dermatology and dermatopathology fellow evaluation despite different periods of ACGME accreditation: results of a national survey.

BACKGROUND: Fellow evaluation is required by the Accreditation Council for Graduate Medical Education (ACGME). Procedural dermatology fellowship accreditation by the ACGME began in 2003 while dermatopathology accreditation began in 1976. OBJECTIVE: The objective was to compare fellow evaluation rigor between ACGME-accredited procedural dermatology and dermatopathology fellowships. METHODS: Questionnaires were mailed to fellowship directors of the ACGME-accredited (2006-2007) procedural dermatology and dermatopathology fellowship programs. Information was collected regarding evaluation form development, delivery, and collection. RESULTS: The response rates were 74% (25/34) and 53% (24/45) for procedural and dermatopathology fellowship programs, respectively. Sixteen percent (4/25) of procedural dermatology and 25% (6/24) of dermatopathology programs do not evaluate fellows. Fifty percent or less of program (4/8 procedural dermatology and 3/7 dermatopathology) evaluation forms address all six core competencies required by the ACGME. CONCLUSION: Procedural fellowships are evaluating fellows as rigorously as the more established dermatopathology fellowships. Both show room for improvement because one in five programs reported not evaluating fellows and roughly half of the evaluation forms provided do not address the six ACGME core competencies.

Implementation Research to Address the United States Health Disadvantage: Report of a National Heart, Lung, and Blood Institute Workshop.

Four decades ago, U.S. life expectancy was within the same range as other high-income peer countries. However, during the past decades, the United States has fared worse in many key health domains resulting in shorter life expectancy and poorer health-a health disadvantage. The National Heart, Lung, and Blood Institute convened a panel of national and international health experts and stakeholders for a Think Tank meeting to explore the U.S. health disadvantage and to seek specific recommendations for implementation research opportunities for heart, lung, blood, and sleep disorders. Recommendations for National Heart, Lung, and Blood Institute consideration were made in several areas including understanding the drivers of the disadvantage, identifying potential solutions, creating strategic partnerships with common goals, and finally enhancing and fostering a research workforce for implementation research. Key recommendations included exploring why the United States is doing better for health indicators in a few areas compared with peer countries; targeting populations across the entire socioeconomic spectrum with interventions at all levels in order to prevent missing a substantial proportion of the disadvantage; assuring partnership have high-level goals that can create systemic change through collective impact; and finally, increasing opportunities for implementation research training to meet the current needs. Connecting with the research community at large and building on ongoing research efforts will be an important strategy. Broad partnerships and collaboration across the social, political, economic, and private sectors and all civil society will be critical-not only for implementation research but also for implementing the findings to have the desired population impact. Developing the relevant knowledge to tackle the U.S. health disadvantage is the necessary first step to improve U.S. health outcomes.

Relation of Carotid Intima-Media Thickness to Cardiovascular Events in Black Americans (From the Jackson Heart Study).

Although several prospective studies have reported independent relations between carotid intima-media thickness (CIMT) and risk of incident cardiovascular diseases (CVD) in primarily non-African-American (AA) cohorts, the utility of CIMT values for the prediction of incident coronary heart disease and stroke events in blacks remain unclear. At the baseline examination (2000 to 2004) of the Jackson Heart Study, AA adults 21 to 94 years of age (mean 54) underwent bilateral far-wall CIMT measurement (mean 0.76 mm). Incident CVD events were then assessed over 7 to 11 years of follow-up (2000 to 2011) from samples of 2,463 women (107 CVD events) and 1,338 men (64 CVD events) who were free of clinical CVD at baseline. Each 0.2-mm increase in CIMT was associated with age-adjusted incident CVD hazard ratios of 1.4 (95% confidence interval 1.2, 1.5) for women and 1.3 (1.1, 1.6) for men. Classification accuracy improved only slightly when comparing multivariable models that used traditional risk factors alone with models that added CIMT: C-statistics 0.837 (0.794, 0.881) versus 0.842 (0.798, 0.886) in women and 0.754 (0.683, 0.826) versus 0.763 (0.701, 0.825) in men. Similarly, risk reclassification was only mildly improved by adding CIMT: Net Reclassification Index 0.13 (p = 0.05) and 0.05 (p = 0.50) for women and men, respectively; Integrated Discrimination Improvement 0.02 (p = 0.02) and 0.01 (p = 0.26) for women and men, respectively. In conclusion, CIMT was associated with incident CVD but provided modest incremental improvement in risk reclassification beyond traditional risk factors in a community-based AA cohort.

Multilevel Interventions Targeting Obesity: Research Recommendations for Vulnerable Populations.

INTRODUCTION: The origins of obesity are complex and multifaceted. To be successful, an intervention aiming to prevent or treat obesity may need to address multiple layers of biological, social, and environmental influences. METHODS: NIH recognizes the importance of identifying effective strategies to combat obesity, particularly in high-risk and disadvantaged populations with heightened susceptibility to obesity and subsequent metabolic sequelae. To move this work forward, the National Heart, Lung, and Blood Institute, in collaboration with the NIH Office of Behavioral and Social Science Research and NIH Office of Disease Prevention convened a working group to inform research on multilevel obesity interventions in vulnerable populations. The working group reviewed relevant aspects of intervention planning, recruitment, retention, implementation, evaluation, and analysis, and then made recommendations. RESULTS: Recruitment and retention techniques used in multilevel research must be culturally appropriate and suited to both individuals and organizations. Adequate time and resources for preliminary work are essential. Collaborative projects can benefit from complementary areas of expertise and shared investigations rigorously pretesting specific aspects of approaches. Study designs need to accommodate the social and environmental levels under study, and include appropriate attention given to statistical power. Projects should monitor implementation in the multiple venues and include a priori estimation of the magnitude of change expected within and across levels. CONCLUSIONS: The complexity and challenges of delivering interventions at several levels of the social-ecologic model require careful planning and implementation, but hold promise for successful reduction of obesity in vulnerable populations.

Toward resolution of cardiovascular health disparities in African Americans: design and methods of the Jackson Heart Study.

OBJECTIVE: The design, overall methods, and major phenotypes for the all-African-American Jackson Heart Study (JHS) are detailed. METHODS: Participants were enrolled from the three counties that make up the Jackson, Mississippi metropolitan area. Relatives of selected participants were recruited to develop a large, nested family cohort. Participants provided extensive medical and social history, had an array of physical and biochemical measurements and diagnostic procedures, and provided genomic DNA. RESULTS: Data and biologic materials have been collected from 5302 adult African Americans, including 1499 members of 291 families. Participants have a high prevalence of diabetes, hypertension, obesity, and related disorders. DISCUSSION: The JHS dataset and biologic materials (serum, DNA, and cryopreserved cells) offer a valuable resource for the study of diseases that are of particular importance to African Americans.

Treatment of hypertension among African Americans: the Jackson Heart Study.

Hypertension treatment regimens used by African American adults in the Jackson Heart Study were evaluated at the first two clinical examinations (2415 treated hypertensive persons at examination I [exam I], 2000-2004; 2577 at examination II [exam II], 2005-2008). Blood pressure (BP) was below 140/90 mm Hg for 66% and 70% of treated participants at exam I and exam II, respectively. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure treatment targets were met for 56% and 61% at exam I and exam II, respectively. Persons with diabetes or chronic kidney disease were less likely to have BP at target, as were men compared with women. Thiazide diuretics were the most commonly used antihypertensive medication, and persons taking a thiazide were more likely to have their BP controlled than persons not taking them; thiazides were used significantly less among men than women. Although calcium channel blockers are often considered to be effective monotherapy for African Americans, persons using calcium channel blocker monotherapy were significantly less likely to be at target BP than persons using thiazide monotherapy.

Quantitative analysis of mitochondrial DNA deletions in the brains of patients with bipolar disorder and schizophrenia.

Several clinical, genetic and neuroimaging studies implicate mitochondrial dysfunction in the pathophysiology of bipolar disorder and schizophrenia. It has been reported that a mitochondrial DNA (mtDNA) deletion of 4,977 bp, known as the 'common deletion', is associated with both mental illnesses. A lack of normal age-related accumulation of this deletion in schizophrenia and increased occurrence of the common deletion in bipolar disorder have been reported. However, even in the affected bipolar samples, the levels of common deletion were relatively small, indicating that the common deletion did not play a pathophysiological role in respiratory function. We hypothesized that accumulation of multiple mtDNA deletions, rather than the common deletion alone, is involved in the pathophysiology of these two major mental disorders. To test this hypothesis, we assessed mtDNA deletion(s) by comparing the copy number of two regions in mtDNA -- ND1 and ND4 -- using real-time quantitative PCR in the frontal cortex of 84 subjects (30 control, 27 with bipolar disorder, and 27 with schizophrenia). We also assessed the relative amount of mtDNA vs. nuclear DNA and the expression level of DNA polymerase gamma (POLG), which is involved in replicating mtDNA. We observed no association between mtDNA deletions and the two major mental disorders in the frontal cortex, which did not support our hypothesis. We did, however, make the following observations, although they were not significant after Bonferroni correction: (1) the ratio of mtDNA to nuclear DNA was significantly higher in female patients with schizophrenia than in control females ( p =0.040) and (2) in bipolar disorder, the relative amount of mtDNA decreased with age ( p =0.016). furthermore, POLG expression was significantly up-regulated in bipolar disorder ( p =0.036). Our results suggest that abnormalities in the system maintaining replication of mtdna may underlie bipolar disorder and schizophrenia.

Assessing the factorial invariance of Harter's self-concept measures: comparing preadolescents with and without spina bifida using child, parent, and teacher report.

The purpose of this study was to determine whether the structure of children's self-concept, as rated by children themselves on the Self-Perception Profile for Children (SPPC; Harter, 1985), and the structure of children's competence, as rated by their parents on the Rating Scale of Child's Actual Behavior (PRS) and teachers on the Rating Scale of Child's Actual Behavior (TRS; Harter, 1985), are similar across samples of children with and without spina bifida (children were 8 and 9 years of age; n = 68 in each sample). Using confirmatory factor analyses, results revealed that a multidimensional model for the SPPC and the TRS fit the data well for both samples. On the other hand, the model for both mothers' and fathers' PRS ratings did not fit the data for the spina bifida sample. Further tests of factorial invariance conducted on the SPPC and TRS revealed that the spina bifida and able-bodied samples tended to have the same pattern and magnitude of factor loadings for both instruments. There was some invariance, however, in the amount of unique error variance accounted for across samples. These results bolster our confidence in using the SPPC and TRS to compare children with and without spina bifida.

Interstitial cells of Cajal and electrical activity in ganglionic and aganglionic colons of mice.

An antibody directed against Kit protein was used to investigate the distribution of interstitial cells of Cajal (ICC) within the murine colon. The ICC density was greatest in the proximal colon and decreased along its length. The distribution of the different classes of ICC in the aganglionic colons of lethal spotted (ls/ls) mice was found to be similar in age-matched wild-type controls. There were marked differences in the electrical activities of the colons from ls/ls mutants compared with wild-type controls. In ls/ls aganglionic colons, the circular muscle was electrically quiescent compared with the spontaneous spiking electrical activity of wild-type tissues. In ls/ls aganglionic colons, postjunctional neural responses were greatly affected. Inhibitory junction potentials were absent or excitatory junction potentials inhibited by atropine were observed. In conclusion, the distribution of ICC in the ganglionic and aganglionic regions of the colons from ls/ls mutants appeared similar to that of wild-type controls. The electrical activity and neural responses of the circular layer are significantly different in aganglionic segments of ls/ls mutants.