Pamela A. Ohman Strickland

Toxicokinetics and toxicodynamics of paraquat accumulation in mouse brain

Paraquat (PQ) is a potential human neurotoxicant and is used in models of oxidative stress. We determined the toxicokinetics (TK) and toxicodynamics (TD) of PQ in adult mouse brain following repeated or prolonged PQ exposure. PQ accumulated in different brain regions and reached a plateau after approximately 18 i.p. (10 mg/kg) doses and resulted in modest morbidity and mortality unpredictably associated with dose interval and number. PQ had divergent effects on horizontal locomotor behavior depending on the number of doses. PQ decreased striatal dopamine levels after the 18th to 36th i.p. dose (10 mg/kg) and reduced the striatal level of tyrosine hydroxylase. Drinking water exposure to PQ (0.03- 0.05 mg/ml) did not result in any mortality and resulted in concentration and time dependent levels in the brain. The brain half-life of PQ varied with mouse strain. PQ accumulates and may saturate a site in mouse brain resulting in complex PQ level and duration-related consequences. These findings should alter our risk assessment of this compound and demonstrate a useful, but complex dynamic model for understanding the consequences of PQ in the brain.

Features of the Chronic Care Model (CCM) Associated with Behavioral Counseling and Diabetes Care in Community Primary Care

Background: The Chronic Care Model (CCM) was developed to improve chronic disease care, but it may also inform delivery of other types of preventive care. Using hierarchical analyses of service delivery to patients, we explored associations of CCM implementation with diabetes care and counseling for diet or weight loss and physical activity in community-based primary care offices. Methods: Secondary analysis focused on baseline data from 25 practices (with an average of 4 physicians per practice) participating in an intervention trial targeting improved colorectal cancer screening rates. This intervention made no reference to the CCM. CCM implementation was measured through staff and clinical management surveys and was associated with patient care indicators (chart audits and patient questionnaires). Results: Overall, practices had low levels of CCM implementation. However, higher levels of CCM implementation were associated with better diabetes assessment and treatment of patients (P = .009 and .015, respectively), particularly among practices open to “innovation.” Physical activity counseling for obese and, particularly, overweight patients was strongly associated with CCM implementation (P = .0017), particularly among practices open to “innovation”; however, this association did not hold for overweight and obese patients with diabetes. Conclusions: Very modest levels of CCM implementation in unsupported primary care practices are associated with improved care for patients with diabetes and higher rates of behavioral counseling. Incremental incorporation of CCM components is an option, especially for community practices with stretched resources and with cultures of “innovativeness.”

Suppression of the NF-κB Pathway by Diesel Exhaust Particles Impairs Human Antimycobacterial Immunity

Epidemiological studies suggest that chronic exposure to air pollution increases susceptibility to respiratory infections, including tuberculosis in humans. A possible link between particulate air pollutant exposure and antimycobacterial immunity has not been explored in human primary immune cells. We hypothesized that exposure to diesel exhaust particles (DEP), a major component of urban fine particulate matter, suppresses antimycobacterial human immune effector cell functions by modulating TLR-signaling pathways and NF-κB activation. We show that DEP and H37Ra, an avirulent laboratory strain of Mycobacterium tuberculosis, were both taken up by the same peripheral human blood monocytes. To examine the effects of DEP on M. tuberculosis-induced production of cytokines, PBMC were stimulated with DEP and M. tuberculosis or purified protein derivative. The production of M. tuberculosis and purified protein derivative-induced IFN-γ, TNF-α, IL-1β, and IL-6 was reduced in a DEP dose-dependent manner. In contrast, the production of anti-inflammatory IL-10 remained unchanged. Furthermore, DEP stimulation prior to M. tuberculosis infection altered the expression of TLR3, -4, -7, and -10 mRNAs and of a subset of M. tuberculosis-induced host genes including inhibition of expression of many NF-κB (e.g., CSF3, IFNG, IFNA, IFNB, IL1A, IL6, and NFKBIA) and IFN regulatory factor (e.g., IFNG, IFNA1, IFNB1, and CXCL10) pathway target genes. We propose that DEP downregulate M. tuberculosis-induced host gene expression via MyD88-dependent (IL6, IL1A, and PTGS2) as well as MyD88-independent (IFNA, IFNB) pathways. Prestimulation of PBMC with DEP suppressed the expression of proinflammatory mediators upon M. tuberculosis infection, inducing a hyporesponsive cellular state. Therefore, DEP alters crucial components of antimycobacterial host immune responses, providing a possible mechanism by which air pollutants alter antimicrobial immunity.

Using Learning Teams for Reflective Adaptation (ULTRA): Insights From a Team-Based Change Management Strategy in Primary Care

PURPOSE The Using Learning Teams for Reflective Adaptation (ULTRA) study used facilitated reflective adaptive process (RAP) teams to enhance communication and decision making in hopes of improving adherence to multiple clinical guidelines; however, the study failed to show significant clinical improvements. The purpose of this study was to examine qualitative data from 25 intervention practices to understand how they engaged in a team-based collaborative change management strategy and the types of issues they addressed. METHODS We analyzed field notes and interviews from a multimethod practice assessment, as well as field notes and audio-taped recordings from RAP meetings, using an iterative group process and an immersion-crystallization approach. RESULTS Despite a history of not meeting regularly, 18 of 25 practices successfully convened improvement teams. There was evidence of improved practice-wide communication in 12 of these practices. At follow-up, 8 practices continued RAP meetings and found the process valuable in problem solving and decision making. Seven practices failed to engage in RAP primarily because of key leaders dominating the meeting agenda or staff members hesitating to speak up in meetings. Although the number of improvement targets varied considerably, most RAP teams targeted patient care-related issues or practice-level organizational improvement issues. Not a single practice focused on adherence to clinical care guidelines. CONCLUSION Primary care practices can successfully engage in facilitated team meetings; however, leaders must be engaged in the process. Additional strategies are needed to engage practice leaders, particularly physicians, and to target issues related to guideline adherence.

Improving Outcomes for High-Risk Diabetics Using Information Systems

Background: Diabetes care requires management of complex clinical information. We examine the relationship between diabetic outcomes and practices’ use of information. Methods: We performed a cross-sectional, secondary analysis of baseline data from 50 community primary care practices participating in a practice improvement project. Medical record review assessed clinical targets for diabetes (HbA1c ≤8, LDL ≤100, BP ≤130/85). Practices’ use of information was derived from clinician responses to a survey on their use of clinical information systems for patient identification and tracking. Hierarchical linear modeling examined relationships between patient outcomes and practice use of information, controlling for patient level covariates (age, gender, hypertension, and cardiovascular comorbidities) and practice level covariates (solo/group, and electronic health record [EHR] presence). Results: Practices’ use of identification and tracking systems significantly (P < .007 and 0.002) increased odds of achieving diabetes care targets (odds ratio [OR] 1.23 95%, confidence interval [CI] 1.06 to 1.44, and OR 1.32 95% CI 1.11 to 1.59). For diabetic patients with hypertension, odds of hypertension control were higher with higher use of tracking systems (OR = 1.52, P = .0017) and reflected similar trend with higher use of identification systems (OR = 1.28, P = .1349). EHR presence was not associated with attainment of clinical targets. Conclusions: Use of relatively simple systems to identify and track patient information can improve diabetic care outcomes. Practices making investments in an EHR must recognize that this technology alone is not sufficient for achieving desirable clinical outcomes. Researchers must explore the interrelationships of organizational factors necessary for successful information use.

Intraclass correlation estimates for cancer screening outcomes: estimates and applications in the design of group-randomized cancer screening studies.

BACKGROUND Screening has become one of our best tools for early detection and prevention of cancer. The group-randomized trial is the most rigorous experimental design for evaluating multilevel interventions. However, identifying the proper sample size for a group-randomized trial requires reliable estimates of intraclass correlation (ICC) for screening outcomes, which are not available to researchers. We present crude and adjusted ICC estimates for cancer screening outcomes for various levels of aggregation (physician, clinic, and county) and provide an example of how these ICC estimates may be used in the design of a future trial. METHODS Investigators working in the area of cancer screening were contacted and asked to provide crude and adjusted ICC estimates using the analysis of variance method estimator. RESULTS Of the 29 investigators identified, estimates were obtained from 10 investigators who had relevant data. ICC estimates were calculated from 13 different studies, with more than half of the studies collecting information on colorectal screening. In the majority of cases, ICC estimates could be adjusted for age, education, and other demographic characteristics, leading to a reduction in the ICC. ICC estimates varied considerably by cancer site and level of aggregation of the groups. CONCLUSIONS Previously, only two articles had published ICCs for cancer screening outcomes. We have complied more than 130 crude and adjusted ICC estimates covering breast, cervical, colon, and prostate screening and have detailed them by level of aggregation, screening measure, and study characteristics. We have also demonstrated their use in planning a future trial and the need for the evaluation of the proposed interval estimator for binary outcomes under conditions typically seen in GRTs.

Alteration of peripheral blood monocyte gene expression in humans following diesel exhaust inhalation

Context: Epidemiologic associations between acutely increased cardiorespiratory morbidity and mortality and particulate air pollution are well established, but the effects of acute pollution exposure on human gene expression changes are not well understood. Objective: In order to identify potential mechanisms underlying epidemiologic associations between air pollution and morbidity, we explored changes in gene expression in humans following inhalation of fresh diesel exhaust (DE), a model for particulate air pollution. Materials and methods: Fourteen ethnically homogeneous (white males), young, healthy subjects underwent 60-min inhalation exposures on 2 separate days with clean filtered air (CA) or freshly generated and diluted DE at a concentration of 300 μg/m3 PM2.5. Prior to and 24 h following each session, whole blood was sampled and fractionated for peripheral blood mononuclear cell (PBMC) isolation, RNA extraction, and generation of cDNA, followed by hybridization with Agilent Whole Human Genome (4X44K) arrays. Results: Oxidative stress and the ubiquitin proteasome pathway, as well as the coagulation system, were among hypothesized pathways identified by analysis of differentially expressed genes. Nine genes from these pathways were validated using real-time polymerase chain reaction (PCR) to compare fold change in expression between DE exposed and CA days. Quantitative gene fold changes generated by real-time PCR were directionally consistent with the fold changes from the microarray analysis. Discussion and conclusion: Changes in gene expression connected with key oxidative stress, protein degradation, and coagulation pathways are likely to underlie observed physiologic and clinical outcomes and suggest specific avenues and sensitive time points for further physiologic exploration.

Diesel Exhaust Particle Exposure Causes Redistribution of Endothelial Tube VE-Cadherin

Whether diesel exhaust particles (DEPs) potentially have a direct effect on capillary endothelia was examined by following the adherens junction component, vascular endothelial cell cadherin (VE-cadherin). This molecule is incorporated into endothelial adherens junctions at the cell surface, where it forms homodimeric associations with adjacent cells and contributes to the barrier function of the vasculature (Dejana et al., 2008; Venkiteswaran et al., 2002; Villasante et al., 2007). Human umbilical vein endothelial cells (HUVECs) that were pre-formed into capillary-like tube networks in vitro were exposed to DEPs for 24h. After exposure, the integrity of VE-cadherin in adherens junctions was assessed by immunofluorescence analysis, and demonstrated that increasing concentrations of DEPs caused increasing redistribution of VE-cadherin away from the cell-cell junctions toward intracellular locations. Since HUVEC tube networks are three-dimensional structures, whether particles entered the endothelial cells or tubular lumens was also examined. The data indicate that translocation of the particles does occur. The results, obtained in a setting that removes the confounding effects of inflammatory cells or blood components, suggest that if DEPs encounter alveolar capillaries in vivo, they may be able to directly affect the endothelial cell-cell junctions.

Air Pollution Particulate Matter Alters Antimycobacterial Respiratory Epithelium Innate Immunity

ABSTRACT Inhalation exposure to indoor air pollutants and cigarette smoke increases the risk of developing tuberculosis (TB). Whether exposure to ambient air pollution particulate matter (PM) alters protective human host immune responses against Mycobacterium tuberculosis has been little studied. Here, we examined the effect of PM from Iztapalapa, a municipality of Mexico City, with aerodynamic diameters below 2.5 μm (PM2.5) and 10 μm (PM10) on innate antimycobacterial immune responses in human alveolar type II epithelial cells of the A549 cell line. Exposure to PM2.5 or PM10 deregulated the ability of the A549 cells to express the antimicrobial peptides human β-defensin 2 (HBD-2) and HBD-3 upon infection with M. tuberculosis and increased intracellular M. tuberculosis growth (as measured by CFU count). The observed modulation of antibacterial responsiveness by PM exposure was associated with the induction of senescence in PM-exposed A549 cells and was unrelated to PM-mediated loss of cell viability. Thus, the induction of senescence and downregulation of HBD-2 and HBD-3 expression in respiratory PM-exposed epithelial cells leading to enhanced M. tuberculosis growth represent mechanisms by which exposure to air pollution PM may increase the risk of M. tuberculosis infection and the development of TB.

Biochemical and morphological consequences of human α‐synuclein expression in a mouse α‐synuclein null background

A consensus about the functions of human wild‐type or mutated α‐synuclein (αSYN) is lacking. Both forms of αSYN are implicated in Parkinson’s disease, whereas the wild‐type form is implicated in substance abuse. Interactions with other cellular proteins and organelles may meditate its functions. We developed a series of congenic mouse lines containing various allele doses or combinations of the human wild‐type αSYN (hwαSYN) or a doubly mutated (A30P*A53T) αSYN (hm2αSYN) in a C57Bl/6J line spontaneously deleted in mouse αSYN (C57BL/6JOla). Both transgenes had a functional role in the nigrostriatal system, demonstrated by significant elevations in striatal catecholamines, metabolites and the enzyme tyrosine hydroxylase compared with null‐mice without a transgene. Consequences occurred when the transgenes were expressed at a fraction of the endogenous level. Hemizygous congenic mice did not exhibit any change in the number or size of dopaminergic neurons in the ventral midbrain at 9 months of age. Human αSYN was predominantly located in neuronal cell bodies, neurites, synapses, and in intraneuronal/intraneuritic aggregates. The hm2αSYN transgene resulted in more aggregates and dystrophic neurites than did the hw5 transgene. The hwαSYN transgene resulted in higher expression of two striatal proteins, synaptogamin 7 and UCHL1, compared with the levels of the hm2αSYN transgene. These observations suggest that mutations in αSYN may impair specific functional domains, leaving others intact. These lines may be useful for exploring interactions between hαSYN and environmental or genetic risk factors in dopamine‐related disorders using a mouse model.