Population-Based Randomized Controlled Trial of a Stage-Targeted Physical Activity Intervention

BACKGROUND: Intervention trials with self-selected participants have shown that mailed stage-targeted print materials can increase participation in physical activity in the short term. We examined the effects of a mailed stage-targeted print intervention designed to promote physical activity, in a random sample of adults living in a regional city.

METHOD: Participants (n = 462, 40-60 years of age) were randomly allocated to an intervention (n = 227) or control group (n = 235). Measures included validated 2-week physical activity recall and stage of motivational readiness for physical activity. The intervention consisted of a single mailing of a letter and full-color stage-targeted booklets (specific to precontemplation, contemplation, preparation, and action/maintenance) 1 week postbaseline. Follow-up interviews were conducted at 2 and 6 months postbaseline.

RESULTS: After 2 months, participants in the intervention group were significantly more likely to meet the current American College of Sports Medicine/Centers for Disease Control and Prevention recommendation for sufficient physical activity than those in the control group (adjusted odds ratio [OR] = 2.40; 95% confidence interval [CI] = 1.44-3.99). After 6 months, intervention participants who reported receiving and reading the intervention materials were significantly more likely to be meeting the sufficient physical activity criterion compared with the control group (adjusted OR = 2.03; 95% CI = 1.16-3.56).

CONCLUSIONS: The stage-targeted print intervention was effective in promoting short-term increases in physical activity and was most effective for participants who recognized and used the materials. This low-cost, generalizable intervention has demonstrated potential as a practical population-based physical activity promotion strategy. Further research is required before widespread dissemination would be justified, as additional strategies may be required to ensure sustained change.

Two stage partial classification for inconsistent and imbalanced classes

When deriving classification rules for a non-symmetric database with a binary target class, it is common practice to generate rules for the majority class, then any object which is not covered by a rule of suitable accuracy is by default given the minority class prediction. However, in the case where misclassification costs for the minority class significantly outweigh those of the majority class, this may mean that there are still costly incorrect predictions. We examine the capability of an evolutionary algorithm to detect these potentially costly misclassifications.

The ultrasound appearance of the patellar tendon attachment to the tibia in young athletes is conditional on gender and pubertal stage

This cross-sectional study investigated the imaging appearance of the previous termpatellarnext term tendon attachment to the tibia in young male and female tennis players of different ages and pubertal status. Forty-four competitive young players, who had been playing tennis at least for 2 years, were recruited from a tennis school and local tennis clubs. All subjects had bilateral ultrasound imaging of the previous termpatellarnext term tendon attachment to the tibia. Standard anthropometric measurements, pubertal status and injury history were recorded. Ultrasound appearance of the previous termpatellarnext term tendon attachment was categorised into three stages: cartilage attachment, insertional cartilage and mature attachment. Cartilage attachment was more prevalent in boys (32%) and extended further into puberty (until Tanner stage 4) compared to girls (6% and Tanner stage 1). Tendons with Osgood–Schlatter Disease symptoms (n = 3) did not have a cartilage attachment. Imaging appearance commonly seen in young active athletes, consistent with a clinical diagnosis of OSD, was more common in boys and in the pre- and peri-pubertal stages.

Blood-stage Plasmodium infection induces CD8+ T lymphocytes to parasite-expressed antigens, largely regulated by CD8α+ dendritic cells

Although CD8+ T cells do not contribute to protection against the blood stage of Plasmodium infection, there is mounting evidence that they are principal mediators of murine experimental cerebral malaria (ECM). At present, there is no direct evidence that the CD8+ T cells mediating ECM are parasite-specific or, for that matter, whether parasite-specific CD8+ T cells are generated in response to blood-stage infection. To resolve this and to define the cellular requirements for such priming, we generated transgenic P. berghei parasites expressing model T cell epitopes. This approach was necessary as MHC class I-restricted antigens to blood-stage infection have not been defined. Here, we show that blood-stage infection leads to parasite-specific CD8+ and CD4+ T cell responses. Furthermore, we show that P. berghei-expressed antigens are cross-presented by the CD8α+ subset of dendritic cells (DC), and that this induces pathogen-specific cytotoxic T lymphocytes (CTL) capable of lysing cells presenting antigens expressed by blood-stage parasites. Finally, using three different experimental approaches, we provide evidence that CTL specific for parasite-expressed antigens contribute to ECM.

Truncation of Plasmodium berghei merozoite surface protein 8 does not affect in vivo blood-stage development

Merozoite surface protein 8 (MSP8) has shown promise as a vaccine candidate in the Plasmodium yoelii rodent malaria model and has a proposed role in merozoite invasion of erythrocytes. However, the temporal expression and localisation of MSP8 are unusual for a merozoite antigen. Moreover, in Plasmodium falciparum the MSP8 gene could be disrupted with no apparent effect on in vitro growth. To address the in vivo function of full-length MSP8, we truncated MSP8 in the rodent parasite Plasmodium berghei. PbΔMSP8 disruptant parasites displayed a normal blood-stage growth rate but no increase in reticulocyte preference, a phenomenon observed in P. yoelii MSP8 vaccinated mice. Expression levels of erythrocyte surface antigens were similar in P. berghei wild-type and PbΔMSP8-infected erythrocytes, suggesting that a parasitophorous vacuole function for MSP8 does not involve global trafficking of such antigens. These data demonstrate that a full-length membrane-associated form of PbMSP8 is not essential for blood-stage growth.

Linking attitudes and demographics in a tourist segmentation model : a two-stage approach

Segmentation has been widely studied in tourism research e.g. Dolnicar (2004). Dawley (2006) points that commonly used segmentation variables such as demographics lead to identifiable segments which are not actionable while other useful approaches e.g. psychographics, are actionable but not identifiable. The objective of this paper is to develop a two-stage linkage approach to segmentation whereby cluster analysis using psychographic variables is conducted within demographic group. Demographic groups are selected based on propensity to travel. This research utilizes data generated from a cross-sectional self-completed survey of 49,105 Australian respondents on travel and tourism. The managerial usefulness of this segmentation is assessed. Clearly segments can be directly linked both demographically and psychographically.