Gary Glonek

Effect of social networks on 10 year survival in very old Australians: the Australian longitudinal study of aging

Study objectives: To examine if social networks with children, relatives, friends, and confidants predict survival in older Australians over 10 years after controlling for a range of demographic, health, and lifestyle variables. Design: Prospective longitudinal cohort study (the Australian longitudinal study of aging) Setting: Adelaide, South Australia. Participants: 1477 persons aged 70 years or more living in the community and residential care facilities. Main results: After controlling for a range of demographic, health, and lifestyle variables, greater networks with friends were protective against mortality in the 10 year follow up period. The hazard ratio for participants in the highest tertile of friends networks compared with participants in the lowest group was 0.78 (95%CI 0.65 to 0.92). A smaller effect of greater networks with confidants (hazard ratio = 0.84; 95%CI  = 0.71 to 0.98) was seen. The effects of social networks with children and relatives were not significant with respect to survival over the following decade. Conclusions: Survival time may be enhanced by strong social networks. Among older Australians, these may be important in lengthening survival.

The Effects of Social Networks on Disability in Older Australians

Objective: To investigate the effects of total social networks and specific social net-works with children, relatives, friends, and confidants on disability in mobility and Nagi functional tasks. Methods: Six waves of data from the Australian Longitudinal Study of Ageing were used. Data came from 1,477 participants aged 70 years or older. The effects of total social networks and those with children, relatives, friends, and confidants on transitions in disability status were analyzed using binary and multinomial logistic regression. Results: After controlling for a range of health, environmental, and personal factors, social networks with relatives were protective against developing mobility disability (OR = 0.89; 95% CI = 0.79 to 1.00) and Nagi disability (OR = 0.85; 95% CI = 0.74 to 0.96). Other social subnetworks did not have a consistent effect on the development of disability. Discussion: The effects of social relationships extend beyond disability in activities of daily living. Networks with relatives protect against disability in mobility and Nagi tasks.

Genetic regulators of myelopoiesis and leukemic signaling identified by gene profiling and linear modeling

Mechanisms controlling the balance between proliferation and self‐renewal versus growth suppression and differentiation during normal and leukemic myelopoiesis are not understood. We have used the bi‐potent FDB1 myeloid cell line model, which is responsive to myelopoietic cytokines and activated mutants of the granulocyte macrophage‐colony stimulating factor (GM‐CSF) receptor, having differential signaling and leukemogenic activity. This model is suited to large‐scale gene‐profiling, and we have used a factorial time‐course design to generate a substantial and powerful data set. Linear modeling was used to identify gene‐expression changes associated with continued proliferation, differentiation, or leukemic receptor signaling. We focused on the changing transcription factor profile, defined a set of novel genes with potential to regulate myeloid growth and differentiation, and demonstrated that the FDB1 cell line model is responsive to forced expression of oncogenes identified in this study. We also identified gene‐expression changes associated specifically with the leukemic GM‐CSF receptor mutant, V449E. Signaling from this receptor mutant down‐regulates CCAAT/enhancer‐binding protein α (C/EBPα) target genes and generates changes characteristic of a specific acute myeloid leukemia signature, defined previously by gene‐expression profiling and associated with C/EBPα mutations.

Do social networks affect the use of residential aged care among older Australians

BackgroundOlder peoples social networks with family and friends can affect residential aged care use. It remains unclear if there are differences in the effects of specific (with children, other relatives, friends and confidants) and total social networks upon use of low-level residential care and nursing homes.MethodsData were drawn from the Australian Longitudinal Study of Ageing. Six waves of data from 1477 people aged ≥ 70 collected over nine years of follow-up were used. Multinomial logistic regressions of the effects of specific and total social networks on residential care use were carried out. Propensity scores were used in the analyses to adjust for differences in participants health, demographic and lifestyle characteristics with respect to social networks.ResultsHigher scores for confidant networks were protective against nursing home use (odds ratio [OR] upper versus lower tertile of confidant networks = 0.50; 95%CI 0.33–0.75). Similarly, a significant effect of upper versus lower total network tertile on nursing home use was observed (OR = 0.62; 95%CI 0.43–0.90). Evidence of an effect of children networks on nursing home use was equivocal. Nursing home use was not predicted by other relatives or friends social networks. Use of lower-level residential care was unrelated to social networks of any type. Social networks of any type did not have a significant effect upon low-level residential care use.DiscussionBetter confidant and total social networks predict nursing home use in a large cohort of older Australians. Policy needs to reflect the importance of these particular relationships in considering where older people want to live in the later years of life.

The effects of air pollution on asthma hospital admissions in Adelaide, South Australia, 2003-2013: time-series and case-crossover analyses.

SummaryBackground Air pollution can have adverse health effects on asthma sufferers, but the effects vary with geographic, environmental and population characteristics. There has been no long time-series study in Australia to quantify the effects of environmental factors including pollen on asthma hospitalizations. Objectives This study aimed to assess the seasonal impact of air pollutants and aeroallergens on the risk of asthma hospital admissions for adults and children in Adelaide, South Australia. Methods Data on hospital admissions, meteorological conditions, air quality and pollen counts for the period 2003–2013 were sourced. Time-series analysis and case–crossover analysis were used to assess the short-term effects of air pollution on asthma hospitalizations. For the time-series analysis, generalized log-linear quasi-Poisson and negative binomial regressions were used to assess the relationships, controlling for seasonality and long-term trends using flexible spline functions. For the case–crossover analysis, conditional logistic regression was used to compute the effect estimates with time-stratified referent selection strategies. Results A total of 36,024 asthma admissions were considered. Findings indicated that the largest effects on asthma admissions related to PM2.5, NO2, PM10 and pollen were found in the cool season for children (0–17 years), with the 5-day cumulative effects of 30.2% (95% CI: 13.4–49.6%), 12.5% (95% CI: 6.6–18.7%), 8.3% (95% CI: 2.5–14.4%) and 4.2% (95% CI: 2.2–6.1%) increases in risk of asthma hospital admissions per 10 unit increments, respectively. The largest effect for ozone was found in the warm season for children with the 5-day cumulative effect of an 11.7% (95% CI: 5.8–17.9%) increase in risk of asthma hospital admissions per 10 ppb increment in ozone level. Conclusion Findings suggest that children are more vulnerable and the associations between exposure to air pollutants and asthma hospitalizations tended to be stronger in the cool season compared to the warm season, with the exception of ozone. This study has important public health implications and provides valuable evidence for the development of policies for asthma management.

Incidence, impact on the family and cost of gastroenteritis among 4 to 6-year-old children in South Australia

Background:  Gastroenteritis is an important cause of morbidity in both adults and children worldwide. Although the burden of morbidity and mortality is highest in developing countries, gastroenteritis is still a significant cause of morbidity in Australia, particularly in young children. The aims of the present study were to determine the incidence of gastroenteritis among 4–6‐year‐old children in South Australia, to describe the impact on daily activities of the child and caregiver and estimate the cost of gastroenteritis in this population.

Lower age at menarche affects survival in older Australian women: results from the Australian Longitudinal Study of Ageing

BackgroundWhile menarche indicates the beginning of a womans reproductive life, relatively little is known about the association between age at menarche and subsequent morbidity and mortality. We aimed to examine the effect of lower age at menarche on all-cause mortality in older Australian women over 15 years of follow-up.MethodsData were drawn from the Australian Longitudinal Study of Ageing (n = 1,031 women aged 65-103 years). We estimated the hazard ratio (HR) associated with lower age at menarche using Cox proportional hazards models, and adjusted for a broad range of reproductive, demographic, health and lifestyle covariates.ResultsDuring the follow-up period, 673 women (65%) died (average 7.3 years (SD 4.1) of follow-up for decedents). Women with menses onset < 12 years of age (10.7%; n = 106) had an increased hazard of death over the follow-up period (adjusted HR 1.28; 95%CI 0.99-1.65) compared with women who began menstruating aged ≥ 12 years (89.3%; n = 883). However, when age at menarche was considered as a continuous variable, the adjusted HRs associated with the linear and quadratic terms for age at menarche were not statistically significant at a 5% level of significance (linear HR 0.76; 95%CI 0.56 - 1.04; quadratic HR 1.01; 95%CI 1.00-1.02).ConclusionWomen with lower age at menarche may have reduced survival into old age. These results lend support to the known associations between earlier menarche and risk of metabolic disease in early adulthood. Strategies to minimise earlier menarche, such as promoting healthy weights and minimising family dysfunction during childhood, may also have positive longer-term effects on survival in later life.

Gene profiling for determining pluripotent genes in a time course microarray experiment

In microarray experiments, it is often of interest to identify genes which have a prespecified gene expression profile with respect to time. Methods available in the literature are, however, typically not stringent enough in identifying such genes, particularly when the profile requires equivalence of gene expression levels at certain time points. In this paper, the authors introduce a new methodology, called gene profiling, that uses simultaneous differential and equivalent gene expression level testing to rank genes according to a prespecified gene expression profile. Gene profiling treats the vector of true gene expression levels as a linear combination of appropriate vectors, for example, vectors that give the required criteria for the profile. This gene profile model is fitted to the data, and the resulting parameter estimates are summarized in a single test statistic that is then used to rank the genes. The theoretical underpinnings of gene profiling (equivalence testing, intersection-union tests) are discussed in this paper, and the gene profiling methodology is applied to our motivating stem-cell experiment.

Does dog or cat ownership lead to increased gastroenteritis in young children in South Australia

The aim of this study was to investigate the relationship between dog and cat ownership and gastroenteritis in young children. A diary study of 965 children aged 4-6 years living in rural or semi-rural South Australia was undertaken. Data were collected on pet ownership, drinking water and other risk factors for gastroenteritis. Overall 89% of households had pets and dog ownership was more common than cat ownership. The multivariable models for gastroenteritis and pet ownership indicated that living in a household with a dog or cat was associated with a reduced risk of gastroenteritis (adj. OR 0.71, 95% CI 0.55-0.92; OR 0.70, % CI 0.51-0.97 respectively). This paper adds to the evidence that pets are not a major source of gastroenteritis in the home and lends support to the health benefits of pet ownership. However, this must be weighed against the potential negative consequences, such as dog bites, particularly for this age group.

A Descriptive Model for Microbial Population Dynamics in a Copper Sulphide Bioleaching Heap with Spatial and Physicochemical Considerations

A descriptive mathematical model is a valuable tool that can help understand the relationship between the heap leaching process at the Escondida mine in Chile, the microbial community that participates in the process, and the physical characteristics of the heap, such as the arrangement and the mineral composition of the individual leaching strips. However, the bioleaching process at Escondida is a system, which presents many challenges to modelling. The main challenges relate to heaps design and mineral characteristics, the complex interactions between biological and physicochemical parameters, and the unexpected changes in the heaps operational conditions. The heap is sampled periodically and more than 20 variables, including 16S rRNA gene copy number for 16 different microorganisms, are recorded. The data exhibit complex behaviour, including variable dynamics between strips, systematic differences between lifts of the heap, and spatial and temporal correlations. In this work, we develop a non-linear descriptive model for the microbial population trajectory along the leaching cycle and across the different strips. The parameterisation of the model considers the different dynamics between lifts, and strip specific parameters characterise the behaviour of data from individual strips. The parameterisation also allows for spatial correlation by incorporating the effect of adjacent strips on the microbial population trajectory. The model is found to provide a good fit to the data and captures its behaviour across strips. Residuals showed no systematic patterns of departure between the observed and modelled response. The R2 values ranged from 0.53 to 0.71, indicating a reasonable level of predictive power.