Rediscovery of cold-activated brown adipose tissue (BAT) in humans has boosted research interest in identifying BAT activators for metabolic benefits. Of particular interest are cytokines capable of fat browning. Irisin, derived from FNDC5, is an exercise-induced myokine that drives brown-fat-like thermogenesis in murine white fat. Here we explored whether cold exposure is an afferent signal for irisin secretion in humans and compared it with FGF21, a brown adipokine in rodents. Cold exposure increased circulating irisin and FGF21. We found an induction of irisin secretion proportional to shivering intensity, in magnitude similar to exercise-stimulated secretion. FNDC5 and/or FGF21 treatment upregulated human adipocyte brown fat gene/protein expression and thermogenesis in a depot-specific manner. These results suggest exercise-induced irisin secretion could have evolved from shivering-related muscle contraction, serving to augment brown fat thermogenesis in concert with FGF21. Irisin-mediated muscle-adipose crosstalk may represent a thermogenic, cold-activated endocrine axis that is exploitable in obesity therapeutics development.

The nature and scale of the shocks to the demand for, and the supply of, home childcare during the COVID-19 pandemic provide a unique opportunity to increase our understanding of the division of home labour and the determinants of specialization within the household. We collected real-time data on daily lives to document the impact of measures to control COVID-19 on UK families with children under the age of 12. We document that these families have been doing the equivalent of a working week in childcare, with mothers bearing most of the burden. The additional hours of childcare done by women are less sensitive to their employment than they are for men, leaving many women juggling work and (a lot more) childcare, with likely adverse effects on their mental health and future careers. However, some households, those in which men have not been working, have taken greater steps towards an equal allocation, offering the prospect of sharing the burden of childcare more equally in the future.

In rodents, brown adipose tissue (BAT) regulates cold- and diet-induced thermogenesis (CIT; DIT). Whether BAT recruitment is reversible and how it impacts on energy metabolism have not been investigated in humans. We examined the effects of temperature acclimation on BAT, energy balance, and substrate metabolism in a prospective crossover study of 4-month duration, consisting of four consecutive blocks of 1-month overnight temperature acclimation (24°C [month 1] → 19°C [month 2] → 24°C [month 3] → 27°C [month 4]) of five healthy men in a temperature-controlled research facility. Sequential monthly acclimation modulated BAT reversibly, boosting and suppressing its abundance and activity in mild cold and warm conditions (P < 0.05), respectively, independent of seasonal fluctuations (P < 0.01). BAT acclimation did not alter CIT but was accompanied by DIT (P < 0.05) and postprandial insulin sensitivity enhancement (P < 0.05), evident only after cold acclimation. Circulating and adipose tissue, but not skeletal muscle, expression levels of leptin and adiponectin displayed reciprocal changes concordant with cold-acclimated insulin sensitization. These results suggest regulatory links between BAT thermal plasticity and glucose metabolism in humans, opening avenues to harnessing BAT for metabolic benefits.

There is a widespread belief that peer effects are important in charitable giving but little evidence on how donors respond to their peers. Analysing a unique data set of donations to online fund-raising pages, we find positive and sizeable peer effects: a £10 increase in the mean of past donations increases giving by £2.50, on average. Donations respond to both very large and very small amounts and to changes in the mode. We find little evidence that donations signal charity quality -our preferred explanation is that donors use information on earlier donations to decide what is appropriate for them to give.

The Centre for Market and Public Organisation (CMPO) is a leading research centre, combining expertise in economics, geography and law. Our objective is to study the intersection between the public and private sectors of the economy, and in particular to understand the right way to organise and deliver public services. The Centre aims to develop research, contribute to the public debate and inform policy-making.

The small-changes approach advocated by America on the Move could be useful for addressing childhood obesity by preventing excess weight gain in families.

Context:The contribution of brown adipose tissue (BAT) to the energy balance in humans exposed to sustainable cold has not been completely established, partially because of measurement limitations of both BAT activity and energy expenditure (EE). Objective:The objective of the study was to characterize the role of BAT activation in cold-induced thermogenesis (CIT). Design:This study was a single-blind, randomized crossover intervention. Setting:The study was conducted at the National Institutes of Health Clinical Center.Study Participants: Thirty-one healthy volunteers participated in the study. Interventions:The intervention included mild cold exposure.Main Outcomes: CIT and BAT activation were the main outcomes in this study. Methods:Overnight EE measurement by whole-room indirect calorimeter at 24°C or 19°C was followed by 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (PET) scan. After 36 hours, volunteers crossed over to the alternate study temperature under identical conditions. BAT activity was measured in a 3-dimensional region of interest in the upper torso by comparing the uptake at the two temperatures.Results: Twenty-four volunteers (14 males, 10 females) had a complete data set. When compared with 24°C, exposure at 19°C resulted in increased EE (5.3 Ϯ 5.9%, P Ͻ .001), indicating CIT response and mean BAT activity (10.5 Ϯ 11.1%, P Ͻ .001). Multiple regression analysis indicated that a difference in BAT activity (P Ͻ .001), age (P ϭ .01), and gender (P ϭ .037) were independent contributors to individual variability of CIT. Conclusions:A small reduction in ambient temperature, within the range of climate-controlled buildings, is sufficient to increase human BAT activity, which correlates with individual CIT response. This study uncovers for the first time a spectrum of BAT activation among healthy adults during mild cold exposure not previously recognized by conventional PET and PET-computed tomography methods. The enhancement of cold-induced BAT stimulation may represent a novel environmental strategy in obesity treatment. J C E M O N L I N E B r i e f R e p o r t -E n d o c r i n e R e s e a r c h

The last thirty years saw dramatic increases in the proportion of children living in lone parent households. In 1997 the incoming Labour government initiated a series of policy reforms aimed at reducing this high level of child poverty. A key element of their strategy was a move towards increasing employment rates among families with children by a combination of increased in-work support through the Working Families Tax Credit and active case management of the population on welfare through the New Deal for Lone Parents. The assessment of this policy reform agenda has focused to date mainly on lone mothers' employment and poverty. In this paper we extend this to include at the impact on the numbers of lone parent families and a range of outcomes for mothers and children. We cover mothers' mental well-being and health, child outcomes and relationship patterns. As well as representing the basic facts about employment incomes and hours of work. Our results show there was no significant impact of these policy reforms on family structure. Mothers malaise scores are, unsurprisingly, very high on family break up but they tend to recover after around 2 years. WFTC is found to reduce the spike of high malaise co-incident with the transition into lone parenthood but to have no longer term effects. This decline in malaise is strongly associated with improved financial indicators. Adolescent children in lone parents families report lower self-esteem, more unhappiness, lower quality relationships with the mother and a number of worse or risky behaviours. Difference-in-difference techniques suggest a marked narrowing if these gaps since WFTC. The magnitude of these changes are quite large, half of the gap in selfesteem and unhappiness scores and in truanting, smoking and planning to leave school at age 16 are eliminated after the policy reforms. This strongly suggests that the increases in incomes and employment associated with the reforms have profoundly changed the quality of life children in lone parent families.Keywords: welfare reform, lone parents, tax credits, mental health, child outcomes JEL Classification: H31, J22, J13, I38 Electronic version: http://www.bris.ac.uk/Depts/CMPO/workingpapers/wp182.pdf AcknowledgementsThe authors would like to thank the Leverhulme Foundation for financial support and seminar participants at CASE and Bristol for comments and suggestions.