Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol.

Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. Here, we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition measurements and evaporation kinetics indicate that isoprene SOA is composed of several semivolatile organic compounds (SVOCs), with some reversibly reacting to form oligomers. Model analysis shows that liquid-like bulk diffusivities can be used to fit the observed evaporation kinetics of accumulation mode particles but fail to explain the growth kinetics of bimodal aerosol by significantly under-predicting the evolution of the Aitken mode. In contrast, the semisolid scenario successfully reproduces both evaporation and growth kinetics, with the interpretation that hindered partitioning of SVOCs into large viscous particles effectively promotes the growth of smaller particles that have shorter diffusion time scales. This effect has important implications for the growth of atmospheric ultrafine particles to climatically active sizes.

The effect of gas-phase polycyclic aromatic hydrocarbons on the formation and properties of biogenic secondary organic aerosol particles.

When secondary organic aerosol (SOA) particles are formed by ozonolysis in the presence of gas-phase polycyclic aromatic hydrocarbons (PAHs), their formation and properties are significantly different from SOA particles formed without PAHs. For all SOA precursors and all PAHs, discussed in this study, the presence of the gas-phase PAHs during SOA formation significantly affects particle mass loadings, composition, growth, evaporation kinetics, and viscosity. SOA particles formed in the presence of PAHs have, as part of their compositions, trapped unreacted PAHs and products of heterogeneous reactions between PAHs and ozone. Compared to 'pure' SOA particles, these particles exhibit slower evaporation kinetics, have higher fractions of non-volatile components, like oligomers, and higher viscosities, assuring their longer atmospheric lifetimes. In turn, the increased viscosity and decreased volatility provide a shield that protects PAHs from chemical degradation and evaporation, allowing for the long-range transport of these toxic pollutants. The magnitude of the effect of PAHs on SOA formation is surprisingly large. The presence of PAHs during SOA formation increases mass loadings by factors of two to five, and particle number concentrations, in some cases, by more than a factor of 100. Increases in SOA mass, particle number concentrations, and lifetime have important implications to many atmospheric processes related to climate, weather, visibility, and human health, all of which relate to the interactions between biogenic SOA and anthropogenic PAHs. The synergistic relationship between SOA and PAHs presented here are clearly complex and call for future research to elucidate further the underlying processes and their exact atmospheric implications.

Mycorrhizal phenotypes and the Law of the Minimum.

Mycorrhizal phenotypes arise from interactions among plant and fungal genotypes and the environment. Differences in the stoichiometry and uptake capacity of fungi and plants make arbuscular mycorrhizal (AM) fungi inherently more nitrogen (N) limited and less phosphorus (P) limited than their host plants. Mutualistic phenotypes are most likely in P-limited systems and commensal or parasitic phenotypes in N-limited systems. Carbon (C) limitation is expected to cause phenotypes to shift from mutualism to commensalism and even parasitism. Two experiments compared the influence of fertilizer and shade on mycorrhizas in Andropogon gerardii across three naturally N-limited or P-limited grasslands. A third experiment examined the interactive effects of N and P enrichment and shade on A. gerardii mycorrhizas. Our experiments generated the full spectrum of mycorrhizal phenotypes. These findings support the hypothesis that mutualism is likely in P-limited systems and commensalism or parasitism is likely in N-limited systems. Furthermore, shade decreased C-assimilation and generated less mutualistic mycorrhizal phenotypes with reduced plant and fungal biomass. Soil fertility is a key controller of mycorrhizal costs and benefits and the Law of the Minimum is a useful predictor of mycorrhizal phenotype. In our experimental grasslands arbuscular mycorrhizas can ameliorate P-limitation but not N-limitation.

Evaporation kinetics of laboratory-generated secondary organic aerosols at elevated relative humidity.

Secondary organic aerosols (SOA) dominate atmospheric organic aerosols that affect climate, air quality, and health. Recent studies indicate that, contrary to previously held assumptions, at low relative humidity (RH) these particles are semisolid and evaporate orders of magnitude slower than expected. Elevated relative humidity has the potential to affect significantly formation, properties, and atmospheric evolution of SOA particles. Here we present a study of the effect of RH on the room-temperature evaporation kinetics of SOA particles formed by ozonolysis of α-pinene and limonene. Experiments were carried out on α-pinene SOA particles generated, evaporated, and aged at <5%, 50 and 90% RH, and on limonene SOA particles at <5% and 90% RH. We find that in all cases evaporation begins with a relatively fast phase, during which 30-70% of the particle mass evaporates in 2 h, followed by a much slower evaporation rate. Evaporation kinetics at <5% and 50% RH are nearly the same, while at 90% RH a slightly larger fraction evaporates. In all cases, aging the particles prior to inducing evaporation reduces the evaporative losses; with aging at elevated RH leading to a more significant effect. In all cases, the observed SOA evaporation is nearly size-independent.

Experimental determination of chemical diffusion within secondary organic aerosol particles.

Formation, properties, transformations, and temporal evolution of secondary organic aerosol (SOA) particles depend strongly on SOA phase. Recent experimental evidence from both our group and several others indicates that, in contrast to common models' assumptions, SOA constituents do not form a low-viscosity, well-mixed solution, yielding instead a semisolid phase with high, but undetermined, viscosity. We find that when SOA particles are made in the presence of vapors of semi-volatile hydrophobic compounds, such molecules become trapped in the particles' interiors and their subsequent evaporation rates and thus their rates of diffusion through the SOA can be directly obtained. Using pyrene as the tracer molecule and SOA derived from α-pinene ozonolysis, we find that it takes ~24 hours for half the pyrene to evaporate. Based on the observed pyrene evaporation kinetics we estimate a diffusivity of 2.5 × 10(-21) m(2) s(-1) for pyrene in SOA. Similar measurements on SOA doped with fluoranthene and phenanthrene yield diffusivities comparable to that of pyrene. Assuming a Stokes-Einstein relation, an approximate viscosity of 10(8) Pa s can be calculated for this SOA. Such a high viscosity is characteristic of tars and is consistent with published measurements of SOA particle bounce, evaporation kinetics, and the stability of two reverse-layered morphologies. We show that a viscosity of 10(8) Pa s implies coalescence times of minutes, consistent with the findings that SOA particles formed by coagulation are spherical on the relevant experimental timescales. Measurements on aged SOA particles doped with pyrene yield an estimated diffusivity ~3 times smaller, indicating that hardening occurs with time, which is consistent with the increase in SOA oligomer content, decrease in water uptake, and decrease in evaporation rates previously observed with aging.

Resource limitation is a driver of local adaptation in mycorrhizal symbioses.

Symbioses may be important mechanisms of plant adaptation to their environment. We conducted a reciprocal inoculation experiment to test the hypothesis that soil fertility is a key driver of local adaptation in arbuscular mycorrhizal (AM) symbioses. Ecotypes of Andropogon gerardii from phosphorus-limited and nitrogen-limited grasslands were grown with all possible "home and away" combinations of soils and AM fungal communities. Our results indicate that Andropogon ecotypes adapt to their local soil and indigenous AM fungal communities such that mycorrhizal exchange of the most limiting resource is maximized. Grasses grown in home soil and inoculated with home AM fungi produced more arbuscules (symbiotic exchange structures) in their roots than those grown in away combinations. Also, regardless of the host ecotype, AM fungi produced more extraradical hyphae in their home soil, and locally adapted AM fungi were, therefore, able to sequester more carbon compared with nonlocal fungi. Locally adapted mycorrhizal associations were more mutualistic in the two phosphorus-limited sites and less parasitic at the nitrogen-limited site compared with novel combinations of plants, fungi, and soils. To our knowledge, these findings provide the strongest evidence to date that resource availability generates evolved geographic structure in symbioses among plants and soil organisms. Thus, edaphic origin of AM fungi should be considered when managing for their benefits in agriculture, ecosystem restoration, and soil-carbon sequestration.

Illness conceptualizations among older rural Mexican-Americans with anxiety and depression.

Research on barriers and utilization of mental health services in older ethnic minorities has been productive. However, little is known about the characterization and beliefs about anxiety and depression symptoms among older Mexican-Americans. Exploration of these conceptualizations will lead to better detection and provision of care to this large, yet underserved group. The present study used a mixed methods approach to explore conceptualizations of anxiety and depression in a group of rural older Mexican-Americans. Twenty-five Spanish-speaking participants (mean age 71.2) responded to flyers that solicited individuals who felt "tense or depressed." Participants completed a structured diagnostic interview as well as self-report questionnaires about medical health, anxiety and depressive symptoms, and cognitive functioning. Qualitative interviews included questions about how participants describe, conceptualize, and cope with anxiety and depression symptoms. Sixty-eight percent of the sample met criteria for at least one anxiety or mood disorder with high comorbidity rates. Self-reported symptoms of depression, anxiety, and somatization were below clinical ranges for all participants. Medical illness, cognitive impairment, age, education, and acculturation were not associated with distress. Qualitative analyses revealed that nearly half of the terms used by the sample to describe distress phenomena deviated from Western labels traditionally used to indicate anxious and depressive symptomatology. Multiple methods of symptom endorsement demonstrated that older Mexican-Americans may report distress differently than detected by traditional self-report measures or common Western terminology. Understanding these additional illness conceptualizations may have implications for improving the detection of mental illness and increasing service use among this growing population.

Synergy between secondary organic aerosols and long-range transport of polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs), known for their harmful health effects, undergo long-range transport (LRT) when adsorbed on and/or absorbed in atmospheric particles. The association between atmospheric particles, PAHs, and their LRT has been the subject of many studies yet remains poorly understood. Current models assume PAHs instantaneously attain reversible gas-particle equilibrium. In this paradigm, as gas-phase PAH concentrations are depleted due to oxidation and dilution during LRT, particle-bound PAHs rapidly evaporate to re-establish equilibrium leading to severe underpredictions of LRT potential of particle-bound PAHs. Here we present a new, experimentally based picture in which PAHs trapped inside highly viscous semisolid secondary organic aerosol (SOA) particles, during particle formation, are prevented from evaporation and shielded from oxidation. In contrast, surface-adsorbed PAHs rapidly evaporate leaving no trace. We find synergetic effects between hydrophobic organics and SOA - the presence of hydrophobic organics inside SOA particles drastically slows SOA evaporation to the point that it can almost be ignored, and the highly viscous SOA prevents PAH evaporation ensuring efficient LRT. The data show the assumptions of instantaneous reversible gas-particle equilibrium for PAHs and SOA are fundamentally flawed, providing an explanation for the persistent discrepancy between observed and predicted particle-bound PAHs.

Understanding the social costs of psychosis: the experience of adults affected by psychosis identified within the second Australian National Survey of Psychosis.

BACKGROUND: Social inclusion is a key priority of the Fourth National Mental Health Plan for Australia (2009-2014), with strong evidence for its protective impact on mental health. Social integration has been associated with enhanced well-being for people with mental illnesses such as psychosis. OBJECTIVE: To explore the impact of psychosis on an individual's social and community participation. METHOD: The second Australian national survey of psychosis was conducted across seven Australian sites. Semi-structured interviews with adults living with psychosis assessed mental health status, social and role functioning, life satisfaction and future goals. The cohort comprised 1825 adults with a psychotic illness (59.6% were male; 42.4% were aged 18-34 years; 31.5% had 12 years or more of education) of whom 32.7% had been employed in the past year. RESULTS: Most adults indicated experiencing loneliness (80.1%) and a need for more friends (48.1%). Men were more likely to have never had a long-term relationship (59.4% M, 33.2% F). Even though women were more likely to experience anxiety in social situations [(χ(2)(1) = 8.95, p < 0.01)], they were more likely to have attended a social activity in the past year [χ(2)(2) = 11.84, p < 0.01]. Just over half of the survey participants (56.7%) reported having daily or nearly daily contact with family members. In the past year, 69% had not attended any social activity and 43% described stigma as a barrier. Although 63.2% showed significant impairment in social functioning, only 29.5% had received help for this in the last year. Social isolation and loneliness were rated as major challenges by 37.2% of the cohort. CONCLUSIONS: Social isolation and dysfunction experienced by people with psychosis have not decreased since the last Australian national survey of people with psychosis. Alongside education and employment, social functioning and participation must be addressed to improve social inclusion for people with psychosis. Programs targeting social opportunities (befriending, peer support), social anxiety and social functioning for all stages of psychosis are warranted.

Students' perception of a modified form of PBL using concept mapping.

BACKGROUND: Problem-based learning (PBL) and concept mapping have been shown to promote active and meaningful learning. AIM: To design a method of PBL that includes concept mapping and examine students' perceptions of this form of PBL. METHODS: We designed a 5-phase method of PBL which produced three clearly identifiable mapping phases that reflected the learning activities during the tutorial: (1) the initial understanding of the clinical problem, (2) students' prior knowledge of the problem, (3) the final understanding of the problem following self-directed study. The process of developing the second and third phases of the map involved the students answering questions that they generated on two occasions to give the entire process a 5-phase approach. Each student was exposed to both methods of PBL: a conventional 7-step method (Maastricht type) and the modified PBL (5-phase) method. We used a questionnaire to evaluate the students' perceptions of the two methods in four learning domains. RESULT: The students' ratings for the 5-phase method were significantly higher than for the 7-step method (paired t-test) on all items on the questionnaire. CONCLUSION: The students perceived the 5-phase method as promoting their passion for learning, and developing their cognitive, metacognitive and interpersonal skills.

Top 10 (plus 1) research priorities for expectant families and those with children to age 24 months in Alberta, Canada: results from the Family Research Agenda Initiative Setting (FRAISE) priority setting partnership project.

OBJECTIVE: The study objective was to identify the top 10 research priorities for expectant parents and caregivers of children up to age 24 months. DESIGN: A priority setting partnership using a modified James Lind Alliance approach was implemented. First, a core steering committee was formed, consisting of 17 parents, clinicians and community agency representatives. Second, through in-person collaboration with steering committee members, we developed and distributed a survey to identify research priorities across 12 topics. In total, 596 participants consented and 480 completed the survey. Survey responses were grouped and themed into codes during a consensus-building workshop with steering committee members (n=18). Research and practice experts were consulted to provide feedback on which themes had already been researched. An in-person (n=21) workshop was used to establish the top 34 priorities, which were circulated to the broader steering committee (n=25) via an online survey. Finally, the core steering committee members (n=18) met to determine and rank a top 10 (plus 1) list of research priorities. SETTING: This study was conducted in Alberta, Canada. PARTICIPANTS: Expectant parents and caregivers of children up to age 24 months. RESULTS: Survey results provided 3232 responses, with 202 unique priorities. After expert feedback and steering committee consensus, a list of 34 priorities was moved forward for final consideration. The final top 10 (plus 1) research priorities included three priorities on mental health/relationships, two priorities on each of access to information, immunity and child development, and one priority on each of sleep, pregnancy/labour and feeding. Selecting 11 instead of 10 priorities was based on steering committee consensus. CONCLUSIONS: The findings will direct future maternal-child research, ensuring it is rooted in parent-identified priorities that represent contemporary needs. To provide meaningful outcomes, research in these priority areas must consider diverse socioeconomic backgrounds and experiences.

Distress among rural residents: does employment and occupation make a difference?

OBJECTIVE: This study investigates the relationship between levels of mental health and well-being (in terms of self-reported levels of distress) with employment and occupational status of rural residents, to better inform the provision of mental health services to those in greatest need in rural communities. METHOD: A stratified random sample of community residents in rural and remote New South Wales with over-sampling of remote areas as first stage of a cohort study. Psychological distress was measured using Kessler-10, inclusive of additional items addressing functional impairment (days out of role). Occupational data were classified using Australian and New Zealand Standard Classification of Occupations categories. RESULTS: A total of 2639 adults participated in this baseline phase. Among them, 57% were in paid employment, 30% had retired from the workforce, 6% were permanently unable to work and 2% were unemployed. The highest levels of distress and functional impairment were reported in those permanently unable to work and the unemployed group with rates of 'caseness' (likely mental health disorder) varying from 57% to 69%, compared with 34% of farmers and farm managers and 29% of health workers (P < 0.01). CONCLUSION: The rural unemployed suffer considerable psychological distress and 'disability', yet they are not the target of specific mental health promotion and prevention programs, which are often occasioned by rural adversity, such as drought, and delivered through work-based pathways. Policy-makers and health service providers need to consider the needs of the rural unemployed and those permanently unable to work and how they might be addressed.

Mental health and well-being within rural communities: the Australian rural mental health study.

OBJECTIVE: This paper outlines the methods and baseline data from a multisite cohort study of the determinants and outcomes of mental health and well-being within rural and remote communities. METHODS: A stratified random sample of adults was drawn in non-metropolitan New South Wales using the Australian Electoral Roll, with the aim of recruiting all adult members of each household. Surveys assessed psychological symptoms, physical health and mental disorders, along with individual-, family/household- and community-level characteristics. A stratified subsample completed a telephone-administered World Mental Health-Composite International Diagnostic Interview (World Mental Health-3.0). Proxy measures of child health and well-being were obtained. Follow up of this sample will be undertaken at one, three and five years. RESULTS: A total of 2639 individuals were recruited (1879 households), with 28% from remote/very remote regions. A significant relationship was found between recent distress (Kessler-10 scores), age and remoteness, with a linear reduction of Kessler-10 scores with age and the lowest mean scores in remote regions. CONCLUSIONS: Existing rurality categories cannot address the diverse socio-cultural, economic and environmental characteristics of non-metropolitan regions. While it has limitations, the dataset will enable a fine-grained examination of geographic, household and community factors and provide a unique longitudinal dataset over a five-year period.

Opioid-Related Disparities in Sexual Minority Youth, 2017.

OBJECTIVES: In light of the opioid epidemic, it is essential to understand which subgroups of youth are at elevated risk for opioid use. Sexual minority groups have increased rates of substance use compared to heterosexual youth. Our study aims to examine the prevalence of both prescription opioid misuse and heroin use in adolescents. We then examine odds of prescription opioid misuse and heroin use adjusting for common covariates. METHODS: Using 2017 Youth Risk Behavior Surveillance System data, we examined lifetime odds of prescription opioid misuse and heroin use among sexual minority youth as defined by sexual identity and sexual behavior. We used logistic regression adjusting for age, sex, and race. RESULTS: 28.5% of gay/lesbian and 25.1% of bisexual youth reported misuse compared to 12.5% of heterosexual youth. Nearly 1 in 10 gay/lesbian youth reported a history of heroin use compared to 4.1% of bisexual and 1.1% of heterosexual young people. Among those who reported having a history of sexual contact, those with same sex contact and sexual contact with both sexes had elevated odds of lifetime heroin use compared to those with a history of opposite sex contact only (aOR: 3.77; 95% CI: 1.68, 8.44 and aOR: 7.44; 95% CI: 4.59, 12.06, respectively). CONCLUSIONS: We demonstrated preliminary evidence sexual minority youth have significant opioid-related health disparities with greater odds of lifetime prescription opioid misuse and heroin use. As early exposure to opioids is associated with greater risk for developing an opioid use disorder and increased opioid-morbidity and mortality, it is critical that providers recognize and incorporate the unique needs for sexual minority youth into traditional treatment and prevention models.

Airborne single particle mass spectrometers (SPLAT II & miniSPLAT) and new software for data visualization and analysis in a geo-spatial context.

Understanding the effect of aerosols on climate requires knowledge of the size and chemical composition of individual aerosol particles-two fundamental properties that determine an aerosol's optical properties and ability to serve as cloud condensation or ice nuclei. Here we present our aircraft-compatible single particle mass spectrometers, SPLAT II and its new, miniaturized version, miniSPLAT that measure in-situ and in real-time the size and chemical composition of individual aerosol particles with extremely high sensitivity, temporal resolution, and sizing precision on the order of a monolayer. Although miniSPLAT's size, weight, and power consumption are significantly smaller, its performance is on par with SPLAT II. Both instruments operate in dual data acquisition mode to measure, in addition to single particle size and composition, particle number concentrations, size distributions, density, and asphericity with high temporal resolution. We also present ND-Scope, our newly developed interactive visual analytics software package. ND-Scope is designed to explore and visualize the vast amount of complex, multidimensional data acquired by our single particle mass spectrometers, along with other aerosol and cloud characterization instruments on-board aircraft. We demonstrate that ND-Scope makes it possible to visualize the relationships between different observables and to view the data in a geo-spatial context, using the interactive and fully coupled Google Earth and Parallel Coordinates displays. Here we illustrate the utility of ND-Scope to visualize the spatial distribution of atmospheric particles of different compositions, and explore the relationship between individual particle compositions and their activity as cloud condensation nuclei.

Experimental and observational patterns of density-dependent settlement and survival in the marine fish Gobiosoma.

Dynamics of reef fishes are influenced by settlement and post-settlement processes. How these processes co-vary or interact is often overlooked due to a focus on one process or study design. We approached this problem by conducting both observational and experimental studies of settlement and post-settlement survival in two goby species, Gobiosoma evelynae and G. prochilos, in Tague Bay of St. Croix, U.S. Virgin Islands. Settlement to coral heads on patch reefs was spatially variable, but the spatial patterns were relatively consistent through time: certain coral heads repeatedly received many settlers, while others received few. We investigated factors that could influence settlement and therefore contribute to the patchy distribution of settlers. Coral heads that received more settlers were larger and further from the center of the reef than heads with few settlers. The heads with many settlers also had more resident fishes, suggesting that resident fishes might attract settlers. We conducted a large-scale fish removal experiment and found that variation in settlement rates to coral heads was mostly driven by inherent properties of the coral heads and not by the presence of resident fishes. We then conducted a replicated, smaller-scale experiment, which showed that increasing density of resident fishes decreased settlement and post-settlement survival. Observational data, however, showed that settlers survived at comparable rates on coral heads with high and low fish density. We discuss several alternative hypotheses that might explain this discrepancy in the strength of density-dependence between the observational and experimental studies. One of these explanations, which has not been considered in the literature, is that the difference in the results arose through a correlation between settlement intensity and the quality of either the larvae or the site to which they settled. As a result, higher settlement may not necessarily lead to higher mortality. We develop a graphical model that shows how density-dependence and habitat or larvae quality may interact. Such a model may help to resolve some of the contradictory results obtained among studies of reef fishes.

The CHAPS, SIFTER, and TAPS-R as predictors of (C)AP skills and (C)APD.

PURPOSE: In this study, the authors investigated the relationships between 3 tests used to screen for (central) auditory processing disorder ([C]APD)--the Children's Auditory Performance Scale (CHAPS; W. J. Smoski, M. A. Brunt, & J. C. Tannahill, 1998), the Screening Instrument for Targeting Educational Risk (SIFTER; K. Anderson, 1989), and the Test of Auditory Perceptual Skills--Revised (TAPS-R; M. Y. Gardner, 1997)-and 4 tests used to diagnostically assess for (C)APD: Low-Pass Filtered Speech (LPFS), Competing Sentences (CS), Two-Pair Dichotic Digits (DD), and Frequency Patterns With Linguistic Report (FP). METHOD: The screening and diagnostic (C)APD tests results of 104 children (71 boys, 33 girls) aged 6.9-14.3 years were reviewed following their attendance at a university clinic in Brisbane, Australia. RESULTS: Pearson's product-moment correlation coefficient analysis showed weak (r = .22, p < .05) to moderate (r = .47, p < .01) correlations predominantly between the short-term and working memory test results of the TAPS-R and the DD and FP test results of the (C)AP test battery. Linear and binary logistic regression analyses showed a poor ability of the CHAPS, SIFTER, and TAPS-R test results to predict the individual LPFS, CS, DD, or FP test results or the overall risk for (C)APD. CONCLUSION: The CHAPS, SIFTER, and TAPS-R should be used to highlight concerns about a child but not to determine whether a diagnostic (C)AP assessment is particularly warranted.

Heat or eat: the Low Income Home Energy Assistance Program and nutritional and health risks among children less than 3 years of age.

OBJECTIVES: Public funding for the Low Income Home Energy Assistance Program has never been sufficient to serve more than a small minority of income-eligible households. Low Income Home Energy Assistance Program funding has not increased with recent rapidly rising energy costs, harsh winter conditions, or higher child poverty rates. Although a national performance goal for the Low Income Home Energy Assistance Program is to increase the percentage of recipient households having > or = 1 member < or = 5 years of age, the association of income-eligible households' receipt of the Low Income Home Energy Assistance Program with indicators of well-being in young children has not been evaluated previously. The goal of the current study was to evaluate the association between a family's participation or nonparticipation in the Low Income Home Energy Assistance Program and the anthropometric status and health of their young children. METHODS: In the ongoing Children's Sentinel Nutrition Assessment Project from June 1998 through December 2004, caregivers with children < 3 years of age in 2 emergency departments and 3 primary care clinics in 5 urban sites participated in cross-sectional surveys regarding household demographics, child's lifetime history of hospitalizations, and, for the past 12 months, household public assistance program participation and household food insecurity, measured by the US Food Security Scale. This scale, in accordance with established procedures, classifies households as food insecure if they report that they cannot afford enough nutritious food for all of the members to lead active, healthy lives. On the day of the interview, children's weight, length, and whether the children were admitted acutely to the hospital from the emergency departments were documented. The study sample consisted only of Low Income Home Energy Assistance Program income-eligible renter households without private insurance who also participated in > or = 1 other means-tested program. RESULTS: In this sample of 7074 caregivers, 16% of families received the Low Income Home Energy Assistance Program, similar to the national rate of 17%. Caregivers who received the Low Income Home Energy Assistance Program were more likely to be single (63% vs 54%), US born (77% vs 68%), and older (mother's mean age: 28.1 vs 26.7 years) but were less likely to be employed (44% vs 47%). Households who received the Low Income Home Energy Assistance Program were more likely to receive Supplemental Nutrition Program for Women, Infants, and Children (85% vs 80%), Supplemental Security Income (13% vs 9%), Temporary Assistance for Needy Families (38% vs 23%), and food stamps (59% vs 37%) and to live in subsidized housing (38% vs 19%) compared with nonrecipients. Children in families participating in the Low Income Home Energy Assistance Program were older than children in nonparticipating families (13.6 vs 12.5 months), were less likely to be uninsured (5% vs 9%), and were more likely to have had a low birth weight < or = 2500 g (17% vs 14%). Families participating in the Low Income Home Energy Assistance Program reported more household food insecurity (24% vs 20%) There were no significant group differences between recipients and nonrecipients in caregiver's education or child's gender. After controlling for these potentially confounding variables, including receipt of other means-tested programs, compared with children in recipient households, those in nonrecipient households had greater adjusted odds of being at aggregate nutritional risk for growth problems, defined as children with weight-for-age below the 5th percentile or weight-for-height below the 10th percentile, with significantly lower mean weight-for-age z scores calculated from age- and gender-specific values from the Centers for Disease Control and Prevention 2000 reference data. However, in adjusted analyses, children aged 2 to 3 years in recipient households were not more likely to be overweight (BMI > 95th percentile) than those in nonrecipient households. Rates of age-adjusted lifetime hospitalization excluding birth and the day of the interview did not differ between Low Income Home Energy Assistance Program recipient groups. Among the 4445 of 7074 children evaluated in the 2 emergency departments, children from eligible households not receiving the Low Income Home Energy Assistance Program had greater adjusted odds than those in recipient households of acute hospital admission on the day of the interview. CONCLUSIONS: Even within a low-income renter sample, Low Income Home Energy Assistance Program benefits seem to reach families at the highest social and medical risk with more food insecurity and higher rates of low birth-weight children. Nevertheless, after adjustment for differences in background risk, living in a household receiving the Low Income Home Energy Assistance Program is associated with less anthropometric evidence of undernutrition, no evidence of increased overweight, and lower odds of acute hospitalization from an emergency department visit among young children in low-income renter households compared with children in comparable households not receiving the Low Income Home Energy Assistance Program. The Low Income Home Energy Assistance Program in many states shuts down early each winter when their funding is exhausted. From a clinical perspective, pediatric health providers caring for children from impoverished families should consider encouraging families of these children to apply for the Low Income Home Energy Assistance Program early in the season before funding is depleted. From a public policy perspective, although this cross-sectional study design can only demonstrate associations and not causation, these findings suggest that, particularly as fuel costs and children's poverty rates increase, expanding the Low Income Home Energy Assistance Program funding and meeting the national Low Income Home Energy Assistance Program performance goal of increasing the percentage of recipient households with young children might potentially benefit such children's growth and health.

Effects of substrate specificity on initiating the base excision repair of N-methylpurines by variant human 3-methyladenine DNA glycosylases.

The human 3-methyladenine (AAG, ANPG, MPG) DNA glycosylase excises alkylated purines from DNA. In previous studies, we determined the importance of an active site amino acid (asparagine 169) in the recognition of substrates by AAG. In this study, we characterize the consequences of expressing the AAG variants bearing amino acid substitutions at position 169 in Saccharomyces cerevisiae that lack endogenous 3-methyladenine DNA glycosylase. Survival, mutation induction, and DNA double strand break formation were determined in response to methyl methanesulfonate. The ability of purified wild-type and AAG variants to remove 3-methyladenine and 7-methylguanine, the two most abundant adducts produced by methyl methanesulfonate, was also determined. The N169D AAG variant displayed a approximately 100-fold lower activity for 3-methyladenine as compared to wild-type and did not detectably remove 7-methylguanine. When expressed in S. cerevisiae, the N169D variant provided better protection against methyl methanesulfonate toxicity than wild-type. Fewer strand breaks in vivo were also seen in the presence of the N169D variant following MMS exposure. In contrast, the N169A and N169S AAG variants displayed approximately 30-fold lower activity for 3-methyladenine and 7-methylguanine. Expression of the N169A and N169S AAG variants in S. cerevisiae during methyl methanesulfonate exposure resulted in greater sensitivity, greater mutation induction following MMS exposure, and more strand breaks in vivo. Strand breaks seen in S. cerevisiae that express wild-type AAG or the N169 variants were resolved to varying extents during recovery. In contrast, strand breaks formed in S. cerevisiae that expressed a catalytically inactive AAG variant were not resolved during the recovery times examined. Taken together, the results provide evidence that 3-methyladenine adducts not repaired by base excision repair cause double strand breaks that are not rapidly resolved. Evidence is also provided that the BER intermediates resulting from excision of 7-methylguanine by wild-type AAG contributes to the mutagenicity and cytotoxicity of alkylating agents.