Effectiveness of a once per week delivery of a family-based childhood obesity intervention: a cluster randomised controlled trial.

BACKGROUND: The effectiveness of once per week (OPW) delivery of a family-based childhood obesity programme was compared with twice per week (TPW) delivery in achieving health and behavioural outcomes at a population level and in improving programme attendance. Both programmes were delivered over 10-weeks, and the contact hours in the OPW and TPW programmes were 20 and 35-h, respectively. METHODS: A cluster-randomised controlled trial with stratification by local health district was conducted. Height, weight and global self esteem of participants and parent-reported diet and physical activity were measured at programme commencement and completion and at 6-month follow-up. Attendance was defined as the proportion of total sessions attended. RESULTS: There were no differences between the OPW and TPW arms in changes from pre-programme baseline for body mass index (BMI) z-score and other health and behaviourial measures at programme completion and at follow-up, except for the increase in physical activity outside of the programme at programme completion (OPW, 3.5 h/week; TPW, 1.9 h/week; p = 0.03). OPW and TPW participants attended 71.2% and 69.2% of the total sessions, respectively. Attendance was the only contributing factor to a positive BMI z-score outcome (ß = -2.45, p < 0.01) with no effects of child age and gender, language spoken at home or highest qualification of mother. CONCLUSIONS: A family-based childhood obesity programme can be delivered OPW with no compromise to health or behavioural outcomes compared with TPW. Higher attendance, as a proportion of available sessions, leads to better outcomes for children.

mtDNA analysis of Nile River Valley populations: A genetic corridor or a barrier to migration?

To assess the extent to which the Nile River Valley has been a corridor for human migrations between Egypt and sub-Saharan Africa, we analyzed mtDNA variation in 224 individuals from various locations along the river. Sequences of the first hypervariable segment (HV1) of the mtDNA control region and a polymorphic HpaI site at position 3592 allowed us to designate each mtDNA as being of "northern" or "southern" affiliation. Proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the southern Sudan. At slowly evolving sites within HV1, northern-mtDNA diversity was highest in Egypt and lowest in the southern Sudan, and southern-mtDNA diversity was highest in the southern Sudan and lowest in Egypt, indicating that migrations had occurred bidirectionally along the Nile River Valley. Egypt and Nubia have low and similar amounts of divergence for both mtDNA types, which is consistent with historical evidence for long-term interactions between Egypt and Nubia. Spatial autocorrelation analysis demonstrates a smooth gradient of decreasing genetic similarity of mtDNA types as geographic distance between sampling localities increases, strongly suggesting gene flow along the Nile, with no evident barriers. We conclude that these migrations probably occurred within the past few hundred to few thousand years and that the migration from north to south was either earlier or lesser in the extent of gene flow than the migration from south to north.