Salutary
Widespread Transcriptional Scanning in the Testis Modulates Gene Evolution Rates
Bo Xia et al.
Cell, 23 January 2020, Pages 248-262
Abstract:
The testis expresses the largest number of genes of any mammalian organ, a finding that has long puzzled molecular biologists. Our single-cell transcriptomic data of human and mouse spermatogenesis provide evidence that this widespread transcription maintains DNA sequence integrity in the male germline by correcting DNA damage through a mechanism we term transcriptional scanning. We find that genes expressed during spermatogenesis display lower mutation rates on the transcribed strand and have low diversity in the population. Moreover, this effect is fine-tuned by the level of gene expression during spermatogenesis. The unexpressed genes, which in our model do not benefit from transcriptional scanning, diverge faster over evolutionary timescales and are enriched for sensory and immune-defense functions. Collectively, we propose that transcriptional scanning shapes germline mutation signatures and modulates mutation rates in a gene-specific manner, maintaining DNA sequence integrity for the bulk of genes but allowing for faster evolution in a specific subset.
Socioeconomic Decline and Death: Midlife Impacts of Graduating in a Recession
Hannes Schwandt & Till von Wachter
NBER Working Paper, January 2020
Abstract:
This paper uses several large cross-sectional data sources and a new approach to estimate midlife effects of entering the labor market in a recession on mortality by cause and various measures of socioeconomic status. We find that cohorts coming of age during the deep recession of the early 1980s suffer increases in mortality that appear in their late 30s and further strengthen through age 50. We show these mortality impacts are driven by disease-related causes such as heart disease, lung cancer, and liver disease, as well as drug overdoses. At the same time, unlucky middle-aged labor market entrants earn less and work more while receiving less welfare support. They are also less likely to be married, more likely to be divorced, and experience higher rates of childlessness. Our findings demonstrate that temporary disadvantages in the labor market during young adulthood can have substantial impacts on lifetime outcomes, can affect life and death in middle age, and go beyond the transitory initial career effects typically studied.
A sales tax is better at promoting healthy diets than the fat tax and the thin subsidy
Zarko Kalamov
Health Economics, forthcoming
Abstract:
We analyze how a sales tax levied on all food products impacts the consumption of healthy food, unhealthy food, and obesity. The sales tax can stimulate the consumption of healthy meals by lowering the time costs of food preparation. Moreover, the sales tax lowers obesity under more general conditions than a tax on unhealthy food (fat tax) and a subsidy on healthy food (thin subsidy). We calibrate the model using recent consumption and time use data from the US. The thin subsidy is counterproductive and increases weight. While both the sales tax and the fat tax mitigate obesity, the former imposes a lower excess burden on consumers.
A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk
Josef Fritz et al.
Current Biology, forthcoming
Abstract:
There is evidence that the spring Daylight Saving Time (DST) transition acutely increases motor vehicle accident (MVA) risk ("DST effect"), which has been partly attributed to sleep deprivation and circadian misalignment. Because spring DST also shifts clock time 1 h later, mornings are darker and evenings brighter, changing illumination conditions for peak traffic density. This daytime-dependent illumination change ("time of day effect") is hypothesized to result in DST-associated afternoon and evening accident risk reductions. Furthermore, sunrise and local photoperiod timing depend on position in time zone. The sun rises at an earlier clock time in the eastern regions of a given time zone than in the western regions, which is thought to induce higher levels of circadian misalignment in the west than in the east ("time zone effect"). This study evaluated the acute consequences of the DST transition on MVAs in a chronobiological context, quantifying DST, time of day, and time zone effects. We used large US registry data, including 732,835 fatal MVAs recorded across all states (1996-2017), and observed that spring DST significantly increased fatal MVA risk by 6%, which was more pronounced in the morning and in locations further west within a time zone. DST-associated MVA risk increased even in the afternoon hours, despite longer daylight hours. The MVA risk increase waned in the week subsequent to DST, and there were no effects of the fall-back transition to Standard Time (ST) on MVA risk, further supporting the hypothesis that DST-transition-associated, preventable circadian misalignment and sleep deprivation might underlie MVA risk increases.
A randomized, double-blind, placebo-controlled trial of blue wavelength light exposure on sleep and recovery of brain structure, function, and cognition following mild traumatic brain injury
William Killgore et al.
Neurobiology of Disease, February 2020
Abstract:
Sleep and circadian rhythms are among the most powerful but least understood contributors to cognitive performance and brain health. Here we capitalize on the circadian resetting effect of blue-wavelength light to phase shift the sleep patterns of adult patients (aged 18-48 years) recovering from mild traumatic brain injury (mTBI), with the aim of facilitating recovery of brain structure, connectivity, and cognitive performance. During a randomized, double-blind, placebo-controlled trial of 32 adults with a recent mTBI, we compared 6-weeks of daily 30-min pulses of blue light (peak λ = 469 nm) each morning versus amber placebo light (peak λ = 578 nm) on neurocognitive and neuroimaging outcomes, including gray matter volume (GMV), resting-state functional connectivity, directed connectivity using Granger causality, and white matter integrity using diffusion tensor imaging (DTI). Relative to placebo, morning blue light led to phase-advanced sleep timing, reduced daytime sleepiness, and improved executive functioning, and was associated with increased volume of the posterior thalamus (i.e., pulvinar), greater thalamo-cortical functional connectivity, and increased axonal integrity of these pathways. These findings provide insight into the contributions of the circadian and sleep systems in brain repair and lay the groundwork for interventions targeting the retinohypothalamic system to facilitate injury recovery.
The Effect of the National Kidney Registry on the Kidney-Exchange Market
Roksana Ghanbariamin & Bobby Chung
Journal of Health Economics, forthcoming
Abstract:
We assess the causal effect of the National Kidney Registry (NKR), the largest national kidney-exchange network in the U.S., on kidney-exchange outcomes. Analyzing a unique database hosted by the Scientific Registry of Transplant Recipients (SRTR) that contains information on all kidney donors, wait-listed candidates, and transplant recipients in the U.S., we find that patients in an NKR hospital are 2.5 to 3 times more likely than their counterparts in a non-NKR hospital to receive a transplant from a living donor, conditional on wait-time. At the same time, NKR participation does not have a significant effect on the desirability of donors and the health status of recipients. We employ various approaches to ensure our finding is robust in addressing the non-random sorting of patients and donors. As far as the outcomes we study, the expansion of the NKR brings about an overall positive impact on the kidney exchange market.
Fatty fish intervention and psychophysiological responses to mental workload in forensic inpatients: A randomized control trial
Anita Hansen et al.
Journal of Psychophysiology, January 2020, Pages 10-18
Abstract:
The overall aim of this randomized controlled trial was to investigate the effect of a long-term fatty fish intervention during winter time on psychophysiological responses, that is, heart rate variability (HRV), to mental workload. Forty-seven forensic inpatients were randomly assigned into a fish group (FG) or a control group (CG). HRV responses to an experimental test procedure consisting of a resting baseline, mental workload, and a resting recovery were measured pre- and post-intervention. The results revealed that the FG showed attenuated physiological responses to mental workload from pretest to posttest by a significant increase in HRV. Additionally, the FG showed a higher HRV during recovery compared to the baseline and test conditions at both pretest and posttest. The CG showed no changes in psychophysiological responses from pretest to posttest to mental workload. Importantly, the CG showed impaired recovery at posttest, indicating a sustained physiological arousal after the stressor (mental workload) ended. Thus, the results indicate that increased fatty fish intake has the potential to increase resilience to mild cognitive stress in human beings with psychiatric illnesses.