Posters in a sample of professional worksites have no effect on objectively measured physical activity.

ISSUE ADDRESSED: Whether posters promoting stair use are effective in increasing objectively measured physical activity in a sample of New Zealand professional employees. METHODS: Forty-six participants (27 men and 19 women) recruited from two professional worksites wore one sealed pedometer during all waking hours (total physical activity [TPV]), and another sealed pedometer during working hours (worksite physical activity [WPV]), for three days over four separate occasions. The study protocol was a crossover design with the first worksite receiving the treatment (posters) for three weeks, followed by a six-week washout period, then a three-week control. The second worksite received the control prior to the treatment period. Measurements were taken at the beginning and end of each three-week block. RESULTS: The posters were ineffective at increasing objectively measured work and total physical activity levels in this sample. Trivial (0.04) to moderate Cohen effect sizes (-0.79) were shown. When posters were visible in the worksites, mean step counts decreased (-868 steps [WPV], and -1,861 steps [TPV]). Women's step counts (-9% [WPV] and -13% [TPV]) were more negatively affected by the posters' appearance when compared with men (-2% [WPV] and -8% [TPV])

The built environment and transport-related physical activity: What we do and do not know

Background: Leisure time physical activities have been a priority in recent years for many health practitioners, with transport-related physical activity (TPA) largely ignored. The urban environment has altered in the last few decades, increasing the reliance on automobiles. Simultaneously we have seen increases in obesity and other non-communicable diseases related to sedentary lifestyles. Methods: Information was sourced from major health databases. The remainder of the literature was directed from citations in articles accessed from the initial search. Results: Clear health benefits result from regular TPA engagement, with opportunities closely linked to accessible urban design infrastructure. Much of the existing evidence, however, has been extracted from cross-sectional research, rather than interventions. As such, drawing causal relationships is not yet possible. Conclusions: Existing evidence necessitates TPA research and promotion should be public health and urban design priorities. Collaborative research needs to incorporate prospective study designs to understand TPA behavior

Physical activity interventions in the workplace: a review and future for New Zealand research

Aim: To examine the worksite physical activity intervention literature and discuss whether the findings are applicable to New Zealand worksite environments. Data sources: Information was sourced from major health databases using key words physical activity, intervention, worksite, workplace, and health promotion. The remainder of the literature search was directed from citations in the articles sourced from the original search. Study selection: Studies included in the review were related to worksite physical activity programmes and/or interventions. Programmes that incorporated screening and other risk behaviour management (for example smoking or stress management) but no health-related physical activity were excluded. Data extraction: The literature was systematically reviewed to evaluate the utility of worksite physical activity programmes for health in general and more specifically for their utility in application to New Zealand worksites. Effect size calculations were generated to quantify major studies. Symphysis: Despite convincing potential, data show little conclusive evidence that worksite interventions do increase long-term adherence to physical activity, provide health benefits, reduce absenteeism, or improve productivity. Problems include contamination through self-selection, high attrition rates, and poor outcome measures. A scarcity of New Zealand worksite physical activity research currently exists with no published accounts of evidence-based programmes identified. Conclusions: A comprehensive appraisal of worksite physical activity literature highlights the complexity of carrying out worksite physical activity interventions and drawing dose-response conclusions. Quality New Zealand research is needed to understand the specifics of the New Zealand workplace and how activity programmes might affect worker behaviour

The contribution of worksite physical activity to total daily physical activity levels in professional occupations

This study investigated the amount of physical activity that occurred during work and total waking hours in a sample of New Zealand professional office workers. Data were collected over three days using a retrospective self-report recall (Three day physical activity recall [3DPAR]), and pedometers (Yamax Digiwalker SW-700). Fifty-six participants (27 men and 29 women) reported their activities over a three-day period and wore two sealed, hip-mounted pedometers. One pedometer was worn during working hours; the other was worn for all waking hours. Results showed that the mean step count over three days for men was 26 609 (+9 194) and 27 489 (+8 222) for women. Relative contributions of work (WPV), non-work (NWPV) and total pedometer values (TPV) were analysed for tertiled activity groups. The high activity group (HAG) achieved more physical activity outside the workday (56%) when compared to the lowest activity group (LAG) (29%). A finding from this study is that the extra activity the HAG accumulated outside the workplace was through active commuting, exercise, and sport and exercise. 3DPAR activity blocks of active transportation, exercise, and sport and exercise showed positive moderate correlations with TPV and NWPV. A moderate positive correlation also existed between pedometer values and 3DPAR (METs.3day-1) data (Spearman correlation=0.28). Odds ratios showed that doing sport and exercise, manual work, and exercise, significantly increased the likelihood of membership in the high pedometer step group. Further research needs to be conducted to determine if worksite interventions can increase health related physical activity of any activity group

The effect of S-substitution at the O6-guanine site on the structure and dynamics of a DNA oligomer containing a G:T mismatch

The effect of S-substitution on the O6 guanine site of a 13-mer DNA duplex containing a G:T mismatch is studied using molecular dynamics. The structure, dynamic evolution and hydration of the S-substituted duplex are compared with those of a normal duplex, a duplex with Ssubstitution on guanine, but no mismatch and a duplex with just a G:T mismatch. The S-substituted mismatch leads to cell death rather than repair. One suggestion is that the G:T mismatch recognition protein recognises the S-substituted mismatch (GS:T) as G:T. This leads to a cycle of futile repair ending in DNA breakage and cell death. We find that some structural features of the helix are similar for the duplex with the G:T mismatch and that with the S-substituted mismatch, but differ from the normal duplex, notably the helical twist. These differences arise from the change in the hydrogen-bonding pattern of the base pair. However a marked feature of the S-substituted G:T mismatch duplex is a very large opening. This showed considerable variability. It is suggested that this enlarged opening would lend support to an alternative model of cell death in which the mismatch protein attaches to thioguanine and activates downstream damage-response pathways. Attack on the sulphur by reactive oxygen species, also leading to cell death, would also be aided by the large, variable opening

Characterization of the Dispersal of Non-Domiciliated Triatoma dimidiata through the Selection of Spatially Explicit Models

Chagas disease is one of the most important neglected diseases in Latin America. Although insecticides have been successfully sprayed to control domiciliated vector populations, this strategy has proven to be ineffective in areas where non-domiciliated vectors immigrating from peridomestic or sylvatic ecotopes can (re-)infest houses. The development of strategies for the control of non-domiciliated vectors has thus been identified by the World Health Organization as a major challenge. Such development primarily requires a description of the spatio-temporal dynamics of infestation by these vectors, and a good understanding of their dispersal. We combined for the first time extensive spatio-temporal data sets describing house infestation dynamics by Triatoma dimidiata inside one village, and spatially explicit population dynamics models. The models fitted and predicted remarkably the observed infestation dynamics. They thus provided both key insights into the dispersal of T. dimidiata in this area, and a suitable mathematical background to evaluate the efficacy of various control strategies. Interestingly, the observed and modelled patterns of infestation suggest that interventions could focus on the periphery of the village, where there is the highest risk of transmission. Such spatial optimization may allow for reducing the cost of control, compensating for repeated interventions necessary for non-domiciliated vectors

Interplay between pleiotropy and secondary selection determines rise and fall of mutators in stress response

Dramatic rise of mutators has been found to accompany adaptation of bacteria in response to many kinds of stress. Two views on the evolutionary origin of this phenomenon emerged: the pleiotropic hypothesis positing that it is a byproduct of environmental stress or other specific stress response mechanisms and the second order selection which states that mutators hitchhike to fixation with unrelated beneficial alleles. Conventional population genetics models could not fully resolve this controversy because they are based on certain assumptions about fitness landscape. Here we address this problem using a microscopic multiscale model, which couples physically realistic molecular descriptions of proteins and their interactions with population genetics of carrier organisms without assuming any a priori fitness landscape. We found that both pleiotropy and second order selection play a crucial role at different stages of adaptation: the supply of mutators is provided through destabilization of error correction complexes or fluctuations of production levels of prototypic mismatch repair proteins (pleiotropic effects), while rise and fixation of mutators occur when there is a sufficient supply of beneficial mutations in replication-controlling genes. This general mechanism assures a robust and reliable adaptation of organisms to unforeseen challenges. This study highlights physical principles underlying physical biological mechanisms of stress response and adaptation

Estimation of heterogeneity in malaria transmission by stochastic modelling of apparent deviations from mass action kinetics

<p>Abstract</p> <p>Background</p> <p>Quantifying heterogeneity in malaria transmission is a prerequisite for accurate predictive mathematical models, but the variance in field measurements of exposure overestimates true micro-heterogeneity because it is inflated to an uncertain extent by sampling variation. Descriptions of field data also suggest that the rate of <it>Plasmodium falciparum </it>infection is not proportional to the intensity of challenge by infectious vectors. This appears to violate the principle of mass action that is implied by malaria biology. Micro-heterogeneity may be the reason for this anomaly. It is proposed that the level of micro-heterogeneity can be estimated from statistical models that estimate the amount of variation in transmission most compatible with a mass-action model for the relationship of infection to exposure.</p> <p>Methods</p> <p>The relationship between the entomological inoculation rate (EIR) for falciparum malaria and infection risk was reanalysed using published data for cohorts of children in Saradidi (western Kenya). Infection risk was treated as binomially distributed, and measurement-error (Poisson and negative binomial) models were considered for the EIR. Models were fitted using Bayesian Markov chain Monte Carlo algorithms and model fit compared for models that assume either mass-action kinetics, facilitation, competition or saturation of the infection process with increasing EIR.</p> <p>Results</p> <p>The proportion of inocula that resulted in infection in Saradidi was inversely related to the measured intensity of challenge. Models of facilitation showed, therefore, a poor fit to the data. When sampling error in the EIR was neglected, either competition or saturation needed to be incorporated in the model in order to give a good fit. Negative binomial models for the error in exposure could achieve a comparable fit while incorporating the more parsimonious and biologically plausible mass action assumption. Models that assume negative binomial micro-heterogeneity predict lower incidence of infection at a given average exposure than do those assuming exposure to be uniform. The negative binomial model moreover provides an estimate of the variance of the within-cohort distribution of the EIR and hence of within cohort heterogeneity in exposure.</p> <p>Conclusion</p> <p>Apparent deviations from mass action kinetics in parasite transmission can arise from spatial and temporal heterogeneity in the inoculation rate, and from imprecision in its measurement. For parasites like <it>P. falciparum</it>, where there is no plausible biological rationale for deviations from mass action, this provides a strategy for estimating true levels of heterogeneity, since if mass-action is assumed, the within-population variance in exposure becomes identifiable in cohort studies relating infection to transmission intensity. Statistical analyses relating infection to exposure thus provide a valid general approach for estimating heterogeneity in transmission but only when they incorporate mass action kinetics and shrinkage estimates of exposure. Such analyses make it possible to include realistic levels of heterogeneity in dynamic models that predict the impact of control measures on transmission intensity.</p