Mortality risk and social network position in resident killer whales: sex differences and the importance of resource abundance.

An individual's ecological environment affects their mortality risk, which in turn has fundamental consequences for life-history evolution. In many species, social relationships are likely to be an important component of an individual's environment, and therefore their mortality risk. Here, we examine the relationship between social position and mortality risk in resident killer whales (Orcinus orca) using over three decades of social and demographic data. We find that the social position of male, but not female, killer whales in their social unit predicts their mortality risk. More socially integrated males have a significantly lower risk of mortality than socially peripheral males, particularly in years of low prey abundance, suggesting that social position mediates access to resources. Male killer whales are larger and require more resources than females, increasing their vulnerability to starvation in years of low salmon abundance. More socially integrated males are likely to have better access to social information and food-sharing opportunities which may enhance their survival in years of low salmon abundance. Our results show that observable variation in the social environment is linked to variation in mortality risk, and highlight how sex differences in social effects on survival may be linked to sex differences in life-history evolution.

Impact of bone turnover markers and/or educational information on persistence to oral bisphosphonate therapy: a community setting-based trial.

UNLABELLED: We examined how the use of bone turnover markers and educational information affects persistence of bisphosphonate use in osteoporotic patients. We found that reporting bone turnover results and/or educational information did not affect persistence. INTRODUCTION: Long-term adherence and persistence to osteoporosis medication are poor. We examined whether reporting of bone turnover marker results, education about osteoporosis, or a combination of both would increase persistence to oral bisphosphonates. METHODS: Two hundred and forty women who were 5 years postmenopausal with BMD at least 2.0 standard deviations below normal were recruited for the study. All women were given a new prescription for alendronate and randomly assigned to one of four groups: (1) bone marker results at baseline, 3 and 12 months; (2) educational materials every month and a membership in the National Osteoporosis Foundation; (3) bone marker and educational information; and (4) control, no information other than usual care. Persistence among randomization groups was tested using survival analysis adjusting for the delay between intervention methods. RESULTS: Of those filling their initial prescription, 95.5% refilled their prescription at the end of the first month, 87% at 3 months, 82% at 6 months, and 78% at 10 months. Overall persistence through 12 months was 54%. There was no difference found among the four groups for persistence time using (p > 0.58). CONCLUSION: Providing bone turnover marker results is not an effective way to enhance early compliance and persistence with drug therapy. While the women in our study felt that bone marker results and educational information were helpful to them, there was no difference in persistence between those who received either bone marker information and/or educational information and those who did not. Because of the unexpected rate of primary nonadherence, this study may be underpowered.

Excretion of sweat and urine pyridinoline crosslinks in healthy controls and subjects with established metabolic bone disease.

Convenient techniques for measuring rates of bone turnover have been developed in recent years with the advent of biochemical markers of bone metabolism. One recent of these techniques is a collection method and quantitative enzyme immunoassay for free pyridinoline crosslinks in human sweat. The concentrations of pyridinoline crosslinks in 5-day sweat collections and first morning void and 24-hour urine collections from healthy subjects and subjects with established metabolic bone disorders were determined. T-scores were higher in the sweat system than in the urine system by up to 10-fold in postmenopausal subjects, women with hyperparathyroidism, and subjects with postmenopausal osteoporosis. For subjects with postmenopausal osteoporosis, receiver-operating characteristic curve analysis yielded areas under the curve of 0.699, 0.629, and 0.520 for sweat pyridinoline, first morning void urine pyridinoline, and 24 hour urine pyridinoline respectively. The areas under the curve of the sweat and first morning void urine measurements were significantly greater (p<0.05) than the 24-hour pyridinoline measurements. Healthy postmenopausal subjects and subjects with postmenopausal osteoporosis were monitored before and during estrogen replacement therapy or alendronate therapy. Sweat pyridinoline values declined by 49.0 +/- 12.4% and 19.4 +/- 19.9% for estrogen and alendronate subjects respectively. We conclude that this non-invasive technique is a sensitive and specific measure of bone resorption and is appropriate as an adjunct to techniques such as bone density and may also be useful in monitoring of response to anti-resorptive therapies.