Organization of Chromatin by Intrinsic and Regulated Phase Separation.

Eukaryotic chromatin is highly condensed but dynamically accessible to regulation and organized into subdomains. We demonstrate that reconstituted chromatin undergoes histone tail-driven liquid-liquid phase separation (LLPS) in physiologic salt and when microinjected into cell nuclei, producing dense and dynamic droplets. Linker histone H1 and internucleosome linker lengths shared across eukaryotes promote phase separation of chromatin, tune droplet properties, and coordinate to form condensates of consistent density in manners that parallel chromatin behavior in cells. Histone acetylation by p300 antagonizes chromatin phase separation, dissolving droplets in vitro and decreasing droplet formation in nuclei. In the presence of multi-bromodomain proteins, such as BRD4, highly acetylated chromatin forms a new phase-separated state with droplets of distinct physical properties, which can be immiscible with unmodified chromatin droplets, mimicking nuclear chromatin subdomains. Our data suggest a framework, based on intrinsic phase separation of the chromatin polymer, for understanding the organization and regulation of eukaryotic genomes.

The WAVE regulatory complex links diverse receptors to the actin cytoskeleton.

The WAVE regulatory complex (WRC) controls actin cytoskeletal dynamics throughout the cell by stimulating the actin-nucleating activity of the Arp2/3 complex at distinct membrane sites. However, the factors that recruit the WRC to specific locations remain poorly understood. Here, we have identified a large family of potential WRC ligands, consisting of ∼120 diverse membrane proteins, including protocadherins, ROBOs, netrin receptors, neuroligins, GPCRs, and channels. Structural, biochemical, and cellular studies reveal that a sequence motif that defines these ligands binds to a highly conserved interaction surface of the WRC formed by the Sra and Abi subunits. Mutating this binding surface in flies resulted in defects in actin cytoskeletal organization and egg morphology during oogenesis, leading to female sterility. Our findings directly link diverse membrane proteins to the WRC and actin cytoskeleton and have broad physiological and pathological ramifications in metazoans.

The bacterial effector VopL organizes actin into filament-like structures.

VopL is an effector protein from Vibrio parahaemolyticus that nucleates actin filaments. VopL consists of a VopL C-terminal domain (VCD) and an array of three WASP homology 2 (WH2) motifs. Here, we report the crystal structure of the VCD dimer bound to actin. The VCD organizes three actin monomers in a spatial arrangement close to that found in the canonical actin filament. In this arrangement, WH2 motifs can be modeled into the binding site of each actin without steric clashes. The data suggest a mechanism of nucleation wherein VopL creates filament-like structures, organized by the VCD with monomers delivered by the WH2 array, that can template addition of new subunits. Similarities with Arp2/3 complex and formin proteins suggest that organization of monomers into filament-like structures is a general and central feature of actin nucleation.

Childhood Asthma Control Test and spirometry values in school-age children.

OBJECTIVE: To determine the relationship between child and parent reports of asthma control using the Childhood Asthma Control Test (C-ACT) and spirometry. METHODS: This descriptive study included 648 children ages 5-11 years from a school-based asthma program. Not well-controlled asthma was defined as forced expiratory volume in 1 s (FEV1) and by FEV1/forced vital capacity (FVC) of 80% predicted or lower. Sensitivity and specificity of C-ACT scores for low FEV1 and FEV1/FVC levels were calculated. Logistic regression was used to obtain the area under the receiver operating characteristic curve (AUC) for C-ACT score categories by FEV1 level. RESULTS: Mean child age was 8.2 years, mean C-ACT score was 20.3 (SD = 3.96), mean FEV1 was 94.3% (SD = 17.1), and mean FEV1/FVC was 81.3 (SD = 8.5). Children with an FEV1 of 80% or less had significantly lower C-ACT scores than those with an FEV1 > 80% (p = .023, t = -2.015, df = 167); 95% CI [. -1.79 to -0.018]). The sensitivity and specificity of a C-ACT score of 19 or less for an FEV1 of 80% predicted or lower were 44.9 and 66.4%. With a C-ACT score of 22 or less, sensitivity and specificity for low FEV1 were 67.7 and 30.9%. The AUC for a C-ACT score of 19 or less and FEV1 of 80% or lower was .444 while the AUC was higher at .507 for a CACT score of 22 or less. CONCLUSION: The C-ACT is a useful screen but spirometry should be performed in children with persistent symptoms to assess current asthma control.

The Feasibility of a School Nurse-Led Mindfulness Program.

The purpose of this study was to evaluate the feasibility of a school nurse-led mindfulness program in a public school. Elementary students in an urban public school system are exposed to many stressors including poverty, family disturbances, and mental health conflicts. Previous research suggests that mindfulness interventions given by teachers promote prosocial behavior and stress reduction; however, there are no studies that have determined whether the school nurse could lead the program. A pre- to posttest design was employed using school-aged children enrolled in the fourth grade who were administered a mindfulness program. The participants were assessed for emotional states before and after the intervention. A total of 12 students completed the intervention. Students found the mindfulness program to be helpful, and the school nurse may be able to successfully complete the intervention. With appropriate planning, school nurses may be able to successfully implement the mindfulness curriculum in an urban public school.

Effect of a school-based asthma clinic on asthma outcomes.

Background: The St. Louis Children's Hospital Healthy Kids Express Asthma (HKEA) program was developed to improve asthma control in children who attend schools with the highest asthma prevalence in the metropolitan area. The HKEA program differs from other programs because unscheduled visits occur at school without parents present. Objective: To assess the effectiveness of the HKEA program via a retrospective quality assurance study. Methods: A chart review was performed to evaluate the change in health-care utilization, absenteeism, staff and student education, inhaler technique checks, and parent satisfaction surveys before and after participation in the program. The Wilcoxon signed rank test, two-way analysis of variance, and descriptive statistics were used to analyze the data. Results: The HKEA program recruited 1076 participants ages 5-15 years during 3 school years, from 2008 to 2011. The participants showed a reduction in emergency department visits (36.9% to 14.2%) and hospitalizations (7.1% to 5.0%) from the year before beginning the program to the third year of the program. Absenteeism was significantly improved, from 59.1% to 27.1%. Staff and student knowledge of asthma improved significantly after completing asthma education programs. More than 90% of participants completed three technique checks of their inhaler and spacer technique and showed significant improvement in their tech check (an inhaler/aero chamber technique check) scores. Parent satisfaction with the HKEA program was rated excellent or very good by 96.9% of the parents. Conclusion: The HKEA program is a novel school-based asthma clinic that is well accepted by parents, and results in less health-care utilization and school absences as well as improved asthma knowledge in participants and the school staff.

Quetiapine v. lithium in the maintenance phase following a first episode of mania: randomised controlled trial.

BackgroundLithium and quetiapine are considered standard maintenance agents for bipolar disorder yet it is unclear how their efficacy compares with each other.AimsTo investigate the differential effect of lithium and quetiapine on symptoms of depression, mania, general functioning, global illness severity and quality of life in patients with recently stabilised first-episode mania.MethodMaintenance trial of patients with first-episode mania stabilised on a combination of lithium and quetiapine, subsequently randomised to lithium or quetiapine monotherapy (up to 800 mg/day) and followed up for 1 year. (Trial registration: Australian and New Zealand Clinical Trials Registry - ACTRN12607000639426.)ResultsIn total, 61 individuals were randomised. Within mixed-model repeated measures analyses, significant omnibus treatment × visit interactions were observed for measures of overall psychopathology, psychotic symptoms and functioning. Planned and post hoc comparisons further demonstrated the superiority of lithium treatment over quetiapine.ConclusionsIn people with first-episode mania treated with a combination of lithium and quetiapine, continuation treatment with lithium rather than quetiapine is superior in terms of mean levels of symptoms during a 1-year evolution.

Asthma control and obesity in urban African American children.

OBJECTIVE: To examine the relationship between body mass index (BMI), gender, age, controller medication use, household smoke exposure, season, and allergic rhinitis status with asthma control in a group of lower income, African American children. We hypothesized that non-obese children would have better asthma control. METHODS: Baseline data from a longitudinal study of children in a school-based asthma program in a Midwest urban area were analyzed. 360 children, ages 4-15 years, who were enrolled in either the 2012-2013 or 2013-2014 program were included. Asthma control was classified using criteria from the 2007 National Asthma Education and Prevention Program. Multiple ordinal regression was performed. RESULTS: The median age was 9 years, 61% had well-controlled asthma, and 29% were obese. The model included all main effects plus two interaction terms and was significant (χ2(7) = 22.17, p =.002). Females who were normal weight (OR, 2.78; 95% CI, 1.38-5.60, p =.004) or overweight (OR, 3.12; 95% CI, 1.26-7.72, p =.014) had better asthma control than obese females. For males, there were no differences by BMI category but males without allergic rhinitis had significantly better asthma control (OR, 2.23; 95% CI, 1.25-3.97, p =.006) than those with allergic rhinitis. CONCLUSIONS: Non-obese girls and non-allergic males had better asthma control. Promotion of healthy activity and nutrition as well as management of allergic rhinitis should be part of the asthma plan in school-based programs in low income urban areas. Innovative approaches to address asthma care in low income populations are essential.

A Pilot Study of Ultrasound-Guided Cryoablation of Invasive Ductal Carcinomas up to 15 mm With MRI Follow-Up and Subsequent Surgical Resection.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of ultrasound-guided cryoablation in treating small invasive ductal carcinoma and to assess the role of contrast-enhanced (CE) MRI in determining the outcome of cryoablation. SUBJECTS AND METHODS: Twenty consecutive participants with invasive ductal carcinomas up to 15 mm, with limited or no ductal carcinoma in situ (DCIS), underwent ultrasound-guided cryoablation. Preablation mammography, ultrasound, and CE-MRI were performed to assess eligibility. Clinical status was evaluated at 1 day, 7-10 days, and 2 weeks after ablation. CE-MRI was performed 25-40 days after ablation, followed by surgical resection within 5 days. RESULTS: Ultrasound-guided cryoablation was uniformly technically successful, and postablation clinical status was good to excellent in all participants. Cryoablation was not clinically successful in 15% (three of 20 patients). Three participants had residual cancer at the periphery of the cryoablation site. Two participants had viable nonmalignant tissue within the central zone of cryoablation-induced necrosis. Postablation CE-MRI had a sensitivity of 0% (0/3) and specificity of 88% (15/17). The predictive value of negative findings on CE-MRI was 83% (15/18). Correlations between cancer characteristics, cryoablation procedural variables, postablation CE-MRI findings, and surgical specimen features were not statistically significant. There were also no significant differences in participants with or without residual cancer. CONCLUSION: In our pilot experience, ultrasound-guided cryoablation of invasive ductal carcinomas up to 15 mm has a clinical failure rate of 15% but is technically feasible and well tolerated by patients. The majority of cryoablation failures are manifest as DCIS outside the cryoablation field. Postablation CE-MRI does not reliably predict cryoablation outcome.

Nutritional support in children and young people with cancer undergoing chemotherapy.

BACKGROUND: It is well documented that malnutrition is a common complication of paediatric malignancy and its treatment. Malnutrition can often be a consequence of cancer itself or a result of chemotherapy. Nutritional support aims to reverse malnutrition seen at diagnosis, prevent malnutrition associated with treatment and promote weight gain and growth. The most effective and safe forms of nutritional support in children and young people with cancer are not known. OBJECTIVES: To determine the effects of any form of parenteral (PN) or enteral (EN) nutritional support, excluding vitamin supplementation and micronutrient supplementation, in children and young people with cancer undergoing chemotherapy and to determine the effect of the nutritional content of PN and EN. This is an update of a previous Cochrane review. SEARCH METHODS: We searched the following databases for the initial review: CENTRAL (The Cochrane Library, Issue 2, 2009), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), CINAHL (1982 to 2006), the National Research Register (2007) and Dissertations & Theses (2007). Experts in the field were also contacted for information on relevant trials. For this update, we searched the same electronic databases from 2006 to September 2013. We also scrutinised the reference lists of included articles to identify additional trials. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing any form of nutritional support with another, or control, in children or young people with cancer undergoing chemotherapy. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials. At least two authors independently assessed quality and extracted data. We contacted trialists for missing information. MAIN RESULTS: The current review included the eight trials from the initial review and six new trials which randomised 595 participants (< 21 years of age) with leukaemias or solid tumours undergoing chemotherapy. The trials were all of low quality with the exception of two of the trials looking at glutamine supplementation. One small trial found that compared to EN, PN significantly increased weight (mean difference (MD) 4.12, 95% CI 1.91 to 6.33), serum albumin levels (MD 0.70, 95% CI 0.14 to 1.26), calorie intake (MD 22.00, 95% CI 5.12 to 38.88) and protein intake (MD 0.80, 95% CI 0.45 to 1.15). One trial comparing peripheral PN and EN with central PN found that mean daily weight gain (MD -27.00, 95% CI -43.32 to -10.68) and energy intake (MD -15.00, 95% CI -26.81 to -3.19) were significantly less for the peripheral PN and EN group, whereas mean change in serum albumin was significantly greater for that group (MD 0.47, 95% CI 0.13 to 0.81, P = 0.008). Another trial with few participants found an increase in mean energy intake (% recommended daily amount) in children fed an energy dense feed compared to a standard calorie feed (MD +28%, 95% CI 17% to 39%). Three studies looked at glutamine supplementation. The evidence suggesting that glutamine reduces severity of mucositis was not statistically significant in two studies (RR 0.64, 95% CI 0.19 to 2.2 and RR 0.85, 95% CI 0.66 to 1.1) and differences in reduction of infection rates were also not significant in two studies (RR 1.0, 95% CI 0.72 to 1.4 and RR 0.98, 95% CI 0.63 to 1.51). Only one study compared olive oil based PN to standard lipid containing PN. Despite similar calorie contents in both feeds, the standard lipid formula lead to greater weight gain (MD -0.34 z-scores, 95% CI -0.68 to 0.00). A single study compared standard EN with fructooligosaccharide containing EN. There was no difference in weight gain between groups (mean difference -0.12, 95% CI -0.57 to 0.33), with adverse effects (nausea) occurring equally between the groups (RR 0.92, 95% CI 0.48 to 1.74). AUTHORS' CONCLUSIONS: There is limited evidence from individual trials to suggest that PN is more effective than EN in well-nourished children and young people with cancer undergoing chemotherapy. The evidence for other methods of nutritional support remains unclear. Limited evidence suggests an energy dense feed increases mean daily energy intake and has a positive effect on weight gain. Evidence suggesting glutamine supplementation reduces incidence and severity of mucositis, infection rates and length of hospital stay is not statistically significant. Further research, incorporating larger sample sizes and rigorous methodology utilising valid and reliable outcome measures, is essential.

Transcatheter aortic valve replacement options for severe aortic stenosis in high-risk patients.

BACKGROUND: Calcific aortic stenosis has now become the most common valvular disease in Western countries. It is a disease of the old and very old. Senile calcific aortic stenosis affects 5% of the population 70 years or older in the United States. Traditionally, the gold standard for treating aortic stenosis has been surgical aortic valve replacement. Unfortunately, surgical aortic valve replacement is, in many cases, not a viable option for this patient population. PURPOSE: This article examines transcatheter aortic valve replacement as an evolving technology and medical procedure with the high-risk and inoperable patients in mind. Since then, the geriatric patient population is ever increasing and the numbers of severe aortic stenosis cases are expected to increase accordingly. It is vital for healthcare professionals to be well informed to give competent care. SUMMARY: International research over the last decade has shown promising results in improved quality of life with regard to pain, functional status, and overall health. This research has expanded to the United States within the last few years. Two transcatheter aortic valve systems are available for use and are being researched. The Placement of AoRTic TraNscathetER Valve Trial (PARTNER trial) (Edwards SAPIEN valve) and the US Pivotal study (Medtronic CoreValve) are 2 large studies being conducted, and the medical community is anxiously awaiting results. CLINICAL IMPLICATIONS: These complex patients require a team approach between the interventional cardiologist, primary cardiologist, cardiac surgeons, and highly trained nursing staff. The transcatheter aortic valve replacement nurse coordinator is a core member of the team, and the contributions of that individual are vital to program success. To avoid complications, careful patient selection is important, and a highly trained valve clinic coordinator must perform a careful and thorough assessment.

Medical anthropology and the physician assistant profession.

Medical anthropology is a subfield of anthropology that investigates how culture influences people's ideas and behaviors regarding health and illness. Medical anthropology contributes to the understanding of how and why health systems operate the way they do, how different people understand and interact with these systems and cultural practices, and what assets people use and challenges they may encounter when constructing perceptions of their own health conditions. The goal of this article is to highlight the methodological tools and analytical insights that medical anthropology offers to the study of physician assistants (PAs). The article discusses the field of medical anthropology; the advantages of ethnographic and qualitative research; and how medical anthropology can explain how PAs fit into improved health delivery services by exploring three studies of PAs by medical anthropologists.

Caring for the disadvantaged: the role of physician assistants.

OBJECTIVE: We investigated community health centers (CHCs) and the roles of physician assistants (PAs) within them. Our goals were to broadly describe PA practice characteristics within CHCs, to explore why PAs work in CHCs, and to understand patient perspectives of PAs. METHODS: We evaluated 10 CHCs in Texas (5 urban and 5 rural), using an ethnographic approach to examine attitudes and beliefs of PAs, medical staff, and patients. RESULTS: Nine of the 10 clinics used PAs interchangeably with physicians, and most medical staff and patients perceived few differences between them. Patients view all providers as highly effective and genuinely concerned for their patients. CONCLUSIONS: We found that clinicians and staff believe in the work they do, report that they function as a team, and seem to like their roles. It appears that working with the medically underserved and economically disadvantaged enables PAs to thrive.

Crystal structure of Spot 14, a modulator of fatty acid synthesis.

Spot 14 (S14) is a protein that is abundantly expressed in lipogenic tissues and is regulated in a manner similar to other enzymes involved in fatty acid synthesis. Deletion of S14 in mice decreased lipid synthesis in lactating mammary tissue, but the mechanism of S14's action is unknown. Here we present the crystal structure of S14 to 2.65 Å and biochemical data showing that S14 can form heterodimers with MIG12. MIG12 modulates fatty acid synthesis by inducing the polymerization and activity of acetyl-CoA carboxylase, the first committed enzymatic reaction in the fatty acid synthesis pathway. Coexpression of S14 and MIG12 leads to heterodimers and reduced acetyl-CoA carboxylase polymerization and activity. The structure of S14 suggests a mechanism whereby heterodimer formation with MIG12 attenuates the ability of MIG12 to activate ACC.

Synergistic phase separation of two pathways promotes integrin clustering and nascent adhesion formation.

Integrin adhesion complexes (IACs) are integrin-based plasma-membrane-associated compartments where cells sense environmental cues. The physical mechanisms and molecular interactions that mediate initial IAC formation are unclear. We found that both p130Cas ('Cas') and Focal adhesion kinase ('FAK') undergo liquid-liquid phase separation in vitro under physiologic conditions. Cas- and FAK- driven phase separation is sufficient to reconstitute kindlin-dependent integrin clustering in vitro with recombinant mammalian proteins. In vitro condensates and IACs in mouse embryonic fibroblasts (MEFs) exhibit similar sensitivities to environmental perturbations including changes in temperature and pH. Furthermore, mutations that inhibit or enhance phase separation in vitro reduce or increase the number of IACs in MEFs, respectively. Finally, we find that the Cas and FAK pathways act synergistically to promote phase separation, integrin clustering, IAC formation and partitioning of key components in vitro and in cells. We propose that Cas- and FAK-driven phase separation provides an intracellular trigger for integrin clustering and nascent IAC formation.

Mechanism of LDL binding and release probed by structure-based mutagenesis of the LDL receptor.

The LDL receptor (LDL-R) mediates cholesterol metabolism in humans by binding and internalizing cholesterol transported by LDL. Several different molecular mechanisms have been proposed for the binding of LDL to LDL-R at neutral plasma pH and for its release at acidic endosomal pH. The crystal structure of LDL-R at acidic pH shows that the receptor folds back on itself in a closed form, obscuring parts of the ligand binding domain with the epidermal growth factor (EGF)-precursor homology domain. We have used a structure-based site-directed mutagenesis approach to examine 12 residues in the extracellular domain of LDL-R for their effect on LDL binding and release. Our studies show that the interface between the ligand binding domain and the EGF-precursor homology domain seen at acidic pH buries residues mediating both LDL binding and release. Our results are consistent with an alternative model of LDL-R whereby multiple modules of the extracellular domain interact with LDL at neutral pH, concurrently positioning key residues so that at acidic pH the LDL-R:LDL interactions become unfavorable, triggering release. After LDL release, the closed form of LDL-R may target its return to the cell surface.

Evidence and implications for early intervention in bipolar disorder.

AIMS: To review the evidence that supports early intervention in the treatment of bipolar disorder. BACKGROUND: Bipolar disorder is a pleomorphic condition, with varying manifestations that are determined by a number of complex factors including the "stage" of illness. It is consequently a notoriously difficult illness to diagnose and as a corollary is associated with lengthy delays in recognition and the initiation of suitable treatment. METHODS: A literature search was conducted using MEDLINE augmented by a manual search. RESULTS: Emerging neuroimaging data suggests that, in contrast to schizophrenia, where at the time of a first-episode of illness there is already discernible volume loss, in bipolar disorder, gross brain structure is relatively preserved, and it is only with recurrences that there is a sequential, but marked loss of brain volume. Recent evidence suggests that both pharmacotherapy and psychotherapy are more effective if instituted early in the course of bipolar disorder, and that with multiple episodes and disease progression there is a noticeable decline in treatment response. CONCLUSIONS: Such data supports the notion of clinical staging, and the tailored implementation of treatments according to the stage of illness. The progressive nature of bipolar disorder further supports the concept that the first episode is a period that requires energetic broad-based treatment, with the hope that this could alter the temporal trajectory of the illness. It also raises hope that prompt treatment may be neuroprotective and that this perhaps attenuates or even prevents the neurostructural and neurocognitive changes seen to emerge with chronicity. This highlights the need for early identification at a population level and the necessity of implementing treatments and services at a stage of the illness where prognosis is optimal.

Pertussis outbreak in an Amish Community: Kent County, Delaware, 2018.

The Amish lead a very simplistic lifestyle free of modern conveniences. They have unique perceptions and beliefs regarding health and illness and generally do not adhere to conventional preventive measures such as immunizations, which can result in un- or under-immunized populations. Populations with low vaccination coverage are at greater risk of outbreaks compared to vaccinated populations as a result of low herd immunity. Over the past two decades, the Delaware Division of Public Health (DPH) has recorded three distinct outbreaks of pertussis in Delaware's Amish community. The third, and most recent, outbreak was detected in May 2018. DPH conducted an outbreak investigation in the Amish community to identify cases, estimate the burden of disease in the community, and implement control measures including vaccination, treatment, and post-exposure prophylaxis. Through the conduct of active surveillance activities, DPH interviewed 134 families and identified 181 confirmed and probable cases of pertussis. The majority of pertussis cases (77%) occurred among children ≤10 years of age, of which 87% were unvaccinated. DPH engaged the Amish community in meetings, distributed educational materials, and provided medication and vaccines in the community to encourage prevention and implement control measures. DPH officially closed the outbreak investigation on December 20, 2018 following three full incubation periods (63 days) without any new pertussis cases identified in the community.

Evaluation of the role of the pediatric nurse practitioner in an inpatient asthma program.

INTRODUCTION: In 1994, pediatric nurse practitioners (PNPs) at St. Louis Children's Hospital developed a program to improve the care of children admitted with asthma. In the Asthma Intervention Model, PNPs directly manage the care of children hospitalized with asthma and are instrumental in hospital-wide education. An evaluation study was conducted to measure effectiveness of this inpatient PNP role. METHODS: Attending physicians, interns, nurses, and families were surveyed regarding their perceptions of the PNPs as care manager and educator. A 16-item asthma knowledge test was administered to interns at the start and conclusion of their intern year. Length of stay, readmission rate, and cost were evaluated. RESULTS: PNPs were found to be effective in the inpatient asthma role by all participants. Significant gains were noted in intern knowledge and confidence in caring for asthma. Interns identified the PNPs as important contributors to their education. No significant differences occurred between interns and PNPs in length of stay, cost, readmissions, or severity of the condition of the asthma patients. DISCUSSION: PNPs in the inpatient asthma setting are effective care managers and educators.

Deciding to opt out of childhood vaccination mandates.

OBJECTIVES: We explore the attitudes and beliefs of parents who consciously choose not to vaccinate their children and the ways in which these parents process information on the pros and cons of vaccines. DESIGN: In-depth, semistructured interviews were conducted. SAMPLE: The study population consisted of 25 parents who do not vaccinate their children, identified through snowball and targeted sampling. METHODS: Participants were asked about their processes and actions when choosing not to vaccinate their children. Interviews were taped and transcribed, and the content was analyzed for emergent themes. RESULTS: Two predominant themes emerged in our data: a desire to collect information on vaccines and trust issues with the medical community. Evidence of sophisticated data collection and information processing was a repeated theme in the interview data. Simultaneously, while participants placed a high value on scientific knowledge, they also expressed high levels of distrust of the medical community. CONCLUSIONS: The challenge for public health is to balance scientific data with popular epidemiology and to maintain legitimacy. Understanding the differences in lay versus expert knowledge has implications for crafting health messages. How experts frame knowledge for consumption has an important impact on this group and their decision-making processes.