Irisin is a polypeptide hormone derived from the proteolytic cleavage of fibronectin-type III domain-containing 5 (FNDC5) protein. Once released to circulation upon exercise or cold exposure, irisin stimulates browning of white adipose tissue (WAT) and uncoupling protein 1 (UCP1) expression, leading to an increase in total body energy expenditure by augmented UCP1-mediated thermogenesis. It is currently unknown whether irisin is secreted by bone upon exercise or whether it regulates bone metabolism in vivo. In this study, we found that 2 weeks of voluntary wheel-running exercise induced high levels of FNDC5 messenger RNA as well as FNDC5/irisin protein expression in murine bone tissues. Increased immunoreactivity due to exercise-induced FNDC5/irisin expression was detected in different regions of exercised femoral bones, including growth plate, trabecular bone, cortical bone, articular cartilage, and bone–tendon interface. Exercise also increased expression of osteogenic markers in bone and that of UCP1 in WAT, and led to bodyweight loss. Irisin intraperitoneal (IP) administration resulted in increased trabecular and cortical bone thickness and osteoblasts numbers, and concurrently induced UCP1 expression in subcutaneous WAT. Lentiviral FNDC5 IP administration increased cortical bone thickness. In vitro studies in bone cells revealed irisin increases osteoblastogenesis and mineralization, and inhibits receptor activator of nuclear factor-kB ligand (RANKL)-induced osteoclastogenesis. Taken together, our findings show that voluntary exercise increases irisin production in bone, and that an increase in circulating irisin levels enhances osteogenesis in mice.

This research examines the relationship between work disability and food insecurity, and tests whether the positive association between disability and food insecurity is accounted for by two mechanisms: economic resources and/or competing consumption needs. A sample (N=6,997) is chosen from the 1999 Panel Study of Income Dynamics (PSID) with over 1,200 households headed by people with disabilities. Findings support both mechanisms but depending on the levels of food insecurity and the types of family economic resources, their success at explaining the relationship of disability with food insecurity varies. In addition, we find that household assets are more effective than income in protecting people with disabilities against food insecurity. Implications for disability policy and food assistance programs are discussed.

This study examines how study participants' financial knowledge and participation in a Child Development Account intervention affects 529 College Savings Plan account holding among caregivers of infants. The study uses data from the SEED for Oklahoma Kids (N = 2,651), a statewide randomized experiment using a probability sample of infants selected from birth records. Results of logit regression show that participants' financial knowledge is positively related to account holding in the treatment group but not in the control group. The interactive effects between financial knowledge and treatment status are statistically significant. This finding implies that the effect of financial knowledge on financial decisions related to college savings is moderated by institutional features, such as incentives, information and access. Results of this study support the propositions of financial capability and suggest that expanding financial capability requires both improved individual financial knowledge and supportive policy.

Using two waves of data from the Child Development Supplement in the Panel Study of Income Dynamics, this study investigates whether parental characteristics (parenting stress, parental warmth, psychological distress, and parent’s self-esteem) mediate household food insecurity’s relations with child behavior problems. Fixed-effects analyses examine data from a low-income sample of 416 children from 249 households. This study finds that parenting stress mediates the effects of food insecurity on child behavior problems. However, two robustness tests produce different results from those of the fixed-effects models. This inconsistency suggests that household food insecurity’s relations to the two types of child behavior problems need to be investigated further with a different methodology and other measures.

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