A Latent Growth Model of Adolescent Physical Activity as a Function of Depressive Symptoms

BackgroundResearch indicates a possible relationship between adolescent depressive symptoms and physical activity, yet few studies have examined whether trajectories of adolescent physical activity differ among adolescents with and without elevated depressive symptoms.PurposeThis study documented change in physical activity from ages 12–17 years among youth with and without elevated depressive symptoms, and examined the influences of key family, physiological, and demographic covariates on activity patterns.MethodsData were from 371 youth. The sample was 50% female; 76% White, 12% African American, 4% Hispanic, 2% Asian, 2% American Indian, and 4% other or mixed races. Mean age was 12.05 years (SD = 1.63) at Time 1. Latent growth curve modeling (LGM), a cohort-sequential design, and a multiple-group design by level of depressive symptoms were employed.ResultsAdolescent physical activity declined significantly from ages 12–17 for those with and without elevated depressive symptoms. Adolescents with elevated symptoms had lower initial levels of physical activity than individuals without. For youth with low depressive symptoms, male sex and parental support of physical activity were related to higher initial levels of physical activity. For youth with elevated depressive symptoms, male sex, being White, and parental support were related to higher initial levels of physical activity. Additionally, for both groups, increases in parent physical activity were related to less of a decline in adolescent physical activity trajectories.ConclusionsFindings highlight the importance of parental support in promoting physical activity among adolescents with and without elevated depressive symptoms.     

Nonexponential T2* decay in white matter

Visualizing myelin in human brain may help the study of diseases such as multiple sclerosis. Previous studies based on T₁ and T₂ relaxation contrast have suggested the presence of a distinct water pool that may report directly on local myelin content. Recent work indicates that T₂* contrast may offer particular advantages over T₁ and T₂ contrast, especially at high field. However, the complex mechanism underlying T₂* relaxation may render interpretation difficult. To address this issue, T₂* relaxation behavior in human brain was studied at 3 and 7 T. Multiple gradient echoes covering most of the decay curve were analyzed for deviations from mono‐exponential behavior. The data confirm the previous finding of a distinct rapidly relaxing signal component (T₂* ～ 6 ms), tentatively attributed to myelin water. However, in extension to previous findings, this rapidly relaxing component displayed a substantial resonance frequency shift, reaching 36 Hz in the corpus callosum at 7 T. The component's fractional amplitude and frequency shift appeared to depend on both field strength and fiber orientation, consistent with a mechanism originating from magnetic susceptibility effects. The findings suggest that T₂* contrast at high field may be uniquely sensitive to tissue myelin content and that proper interpretation will require modeling of susceptibility‐induced resonance frequency shifts. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Outbreak-specific monovalent/bivalent vaccination to control and eradicate virulent ovine footrot

Footrot is a contagious disease of small ruminants which is caused by the bacterium Dichelobacter nodosus. In its virulent form there are severe economic losses and a very significant animal welfare issue. Sheep and goats can be vaccinated for treatment and prevention of the disease. There are 10 different serogroups of D. nodosus (A–I and M) and immunity is serogroup-specific. When all 10 serogroups are presented together in a vaccine, protection persists for only a few months due to “antigenic competition”. Consequently we evaluated the use of sequential monovalent or bivalent vaccines to control/eliminate/eradicate virulent footrot in a longitudinal intervention study on 12 commercial farms in southeast Australia with flock sizes of approximately 1200–4200 sheep. Overall, virulent footrot was eradicated from 4 of the flocks, 2 of which had 2 serogroups, and the others 4 or 5 serogroups. Where there were only 1 or 2 serogroups (3 farms) the clinical response was rapid and dramatic; prevalence was reduced from 45 to 50% before vaccination to 0% (2 farms) or 0.4% (1 farm) after one round of vaccination. In the remaining 9 flocks there were more than 2 serogroups and successive bivalent vaccines were administered leading to eradication of virulent footrot on 2 farms over 4 years and control of the disease on all but 3 of the others. Of the latter farms, 1 discontinued, and 2 initially had poor response to vaccine due to misdiagnosis of serogroup ‘M’, which was previously unknown in Australia. Control was achieved after administration of a serogroup M vaccine. These results provide clear evidence for control, elimination and eradication of virulent footrot by outbreak-specific vaccination in Australia.     

Single-dose vaccine against tick-borne encephalitis

Tick-borne encephalitis (TBE) virus is the most important human pathogen transmitted by ticks in Eurasia. Inactivated vaccines are available but require multiple doses and frequent boosters to induce and maintain immunity. Thus far, the goal of developing a safe, live attenuated vaccine effective after a single dose has remained elusive. Here we used a replication-defective (single-cycle) flavivirus platform, RepliVax, to generate a safe, single-dose TBE vaccine. Several RepliVax-TBE candidates attenuated by a deletion in the capsid gene were constructed using different flavivirus backbones containing the envelope genes of TBE virus. RepliVax-TBE based on a West Nile virus backbone (RV-WN/TBE) grew more efficiently in helper cells than candidates based on Langat E5, TBE, and yellow fever 17D backbones, and was found to be highly immunogenic and efficacious in mice. Live chimeric yellow fever 17D/TBE, Dengue 2/TBE, and Langat E5/TBE candidates were also constructed but were found to be underattenuated. RV-WN/TBE was demonstrated to be highly immunogenic in Rhesus macaques after a single dose, inducing a significantly more durable humoral immune response compared with three doses of a licensed, adjuvanted human inactivated vaccine. Its immunogenicity was not significantly affected by preexisting immunity against WN. Immunized monkeys were protected from a stringent surrogate challenge. These results support the identification of a single-cycle TBE vaccine with a superior product profile to existing inactivated vaccines, which could lead to improved vaccine coverage and control of the disease.     

PREFERENCES FOR THE NORMATIVE BASIS OF HEALTH CARE PRIORITY SETTING: SOME EVIDENCE FROM TWO COUNTRIES

The present paper concerns the criteria people would prefer for prioritising health programmes. It differs from most empirical studies as subjects were not asked about their personal preferences for programmes per se. Rather, they were asked about the principles that should guide the choice of programmes. Four different principles were framed as arguments for alternative programmes. The results from population surveys in Australia and Norway suggest that people are least supportive of the principle that decision makers should follow the stated preferences of the public. Rather, respondents expressed more support for decisions based upon health maximisation, equality and urgency. Copyright © 2012 John Wiley & Sons, Ltd.