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Courtemanche C, Elson-Schwab I, Mashiyama ST, et al. J Immunol 2004;173:3186-3192. Folate is required for one-carbon transfer reactions and the formation of purines and pyrimidines for DNA and RNA synthesis. [...]

Additional work hours may lead to weight gain by decreasing exercise, causing substitution from meals prepared at home to fast food and pre-prepared processed food, or reducing sleep. Substitution toward unhealthy convenience foods could also influence the weight of one's spouse and children, while longer work hours for adults may further impact child weight by reducing parental supervision. I examine the effects of adult work hours on the body mass index (BMI) and obesity status of adults as well as the overweight status of children. Longer hours increase one's own BMI and probability of being obese, but have a smaller and statistically insignificant effect on these outcomes for one's spouse. Mothers', but not mother's spouse's, work hours affect children's probability of being overweight. My estimates imply that changes in labor force participation account for only 1.4% of the rise in adult obesity in recent decades, but a more substantial 10.4% of the growth in childhood overweight. [ABSTRACT FROM AUTHOR]

E-cigarette licensure laws (ELLs) require retailers to obtain a state license to sell e-cigarettes over the counter. This study is the first to comprehensively explore the effect of ELL adoption on youth tobacco product use. Using data from the State Youth Risk Behavior Survey (YRBS) and a difference-in-differences approach, we find no evidence that ELL adoption reduces youth ENDS use. The precision of our estimates allows us to rule out, with 95 % confidence, ELL-induced declines in prior-month, frequent, and everyday youth ENDS use of more than 0.7, 0.3, and 0.4 percentage points, respectively. The pattern of null findings persists when we examine ELLs that impose higher penalties for retailer non-compliance, higher renewable licensure fees, and criminal in addition to civil penalties. We conclude that ELLs have only limited success in curbing access to ENDS among youths., (Copyright © 2024. Published by Elsevier B.V.)

Given that the physicochemical properties of diluted bitumen (dilbit) can differ from those of conventional crude oil, understanding the fate and behavior of this petroleum product in the environment becomes vital. This study involves the analysis of the photolytic behavior of some representative petroleum biomarkers, bicyclic sesquiterpanes (BSs), admantanes (ADs), diamantanes (DAs), and mono- and triaromatic steranes (MASs and TASs), by exposing Cold Lake Blend (CLB) and Alberta Sweet Mixed Blend (MSW) to winter and summer insolation after being spilled onto artificial brines. Aromatic steranes in all control samples remained relatively stable, whereas the biomarkers of BSs, ADs, and DAs were less stable. Similar to the exhaustive loss of the C 10 -C 17 alkanes, 91%-99% of BSs, ADs, and DAs were lost after five days of insolation, especially in summer. Both MASs and TASs were lost gradually in most scenarios, although both of them were lost faster in MSW than observed for CLB. The removal of MASs and TASs did not differ significantly from each other, although their loss was less than observed for PAHs having similar number of rings and greater than for the C 21 -C 33 n-alkanes. Therefore, photooxidation, not evaporation or biodegradation, was the main factor responsible for oxidizing these aromatic steranes. However, biomarkers of BSs, ADs and DAs were mostly lost through evaporation. Therefore, aromatic steranes have the potential to be utilized to evaluate the photolytic behavior of petroleum hydrocarbons, while BSs, ADs, and DAs should not be used for this purpose., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Over the past decade, rising youth use of e-cigarettes and other electronic nicotine delivery systems (ENDS) has contributed to aggressive regulation by state and local governments. Between 2010 and mid-2019, ten states and two large counties adopted ENDS taxes. We use two large national surveys (Monitoring the Future and the Youth Risk Behavior Surveillance System) to estimate the impact of ENDS taxes on youth tobacco use. We find that ENDS taxes reduce youth ENDS consumption, with estimated ENDS tax elasticities of -0.06 to -0.21. However, we estimate sizable positive cigarette cross-tax effects, suggesting economic substitution between cigarettes and ENDS for youth. These substitution effects are particularly large for frequent cigarette smoking. We conclude that the unintended effects of ENDS taxation may considerably undercut or even outweigh any public health gains., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

We estimate the effect of e-cigarette tax rates on e-cigarette prices, e-cigarette sales, and sales of other tobacco products using NielsenIQ Retail Scanner data from 2013 to 2019. We find that 90% of e-cigarette taxes are passed on to consumer retail prices. We then estimate reduced form and instrumental variables regressions to examine the effects of e-cigarette and cigarette taxes and prices on sales. We calculate an e-cigarette own-price elasticity of -2.2 and particularly large elasticity of demand for flavored e-cigarettes. Further, we document a cigarette own-price elasticity of -0.4 and positive cross-price elasticities of demand between e-cigarettes and cigarettes, suggesting economic substitution., (Copyright © 2022. Published by Elsevier B.V.)

Total petroleum hydrocarbons (TPH), n-alkanes, petroleum biomarkers, and polycyclic aromatic hydrocarbons (PAHs) were analyzed in the sediments collected from the shorelines and bottom of St. Clair River, Ontario, Canada. Most of the sampling sites had low TPH (< 20 μg/g). River bottom sediment usually had higher level of TPHs, total alkanes, total biomarkers, and total PAHs than most of the shoreline ones. Mixed biogenic and petrogenic n-alkanes were present in all the sites. Most sites had trace amounts of petroleum biomarkers. Mixed pyrogenic and petrogenic inputs with the predominant petroleum, have contributed to the detected PAHs at all sampling sites. PAHs detected would not show potential toxicity to benthic organisms in all shoreline sampling sites; however, some light molecular weight PAHs (e.g., phenanthrene, 2-methyl naphthalene, and acenaphthylene) are anticipated to have possible adverse impacts to sediment-dwelling organisms in part of the river bottom sediment., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The profitability of life insurance offerings is contingent on accurate projections and pricing of mortality risk. The COVID-19 pandemic created significant uncertainty, with dire mortality predictions from early forecasts resulting in widespread government intervention and greater individual precaution that reduced the projected death toll. We analyze how life insurance companies changed pricing and offerings in response to COVID-19 using monthly data on term life insurance policies from Compulife. We estimate event-study models that exploit well-established variation in the COVID-19 mortality rate based on age and underlying health status. Despite the increase in mortality risk and significant uncertainty, the results generally indicate that life insurance companies did not increase premiums or decrease policy offerings due to COVID-19. Nonetheless, we find some evidence that premiums differentially increased for individuals with very high risk and that some policies were removed for the oldest of the old., (© 2021 American Risk and Insurance Association.)

Early in the pandemic, slowing the spread of novel coronavirus disease 2019 (COVID-19) relied on non-pharmaceutical interventions. All U.S. states adopted social-distancing restrictions in March and April of 2020, though policies varied both in timing and scope. Compared to states with Democratic governors, those with Republican governors often adopted measures for shorter durations and with greater resistance from their residents. In Kentucky, an extremely close gubernatorial election immediately prior to the discovery of SARS-CoV-2 replaced a Republican incumbent with a Democrat, despite Republicans easily winning all other statewide races. This chance election result offers a unique opportunity to examine the impact of early social distancing policies in a relatively conservative, rural, white-working-class state. Our study begins by estimating an event-study model to link adoption of several common social distancing measures-public school closures, bans on large gatherings, closures of entertainment-related businesses such as restaurants, and shelter-in-place orders (SIPOs)-to the growth rate of cases across counties in the Midwest and South in the early stages of the pandemic. These policies combined to slow the daily growth rate of COVID-19 cases by 9 percentage points after 16 days, with SIPOs and entertainment establishment closures accounting for the entire effect. In order to obtain results with more direct applicability to Kentucky, we then estimate a model that interacts the policy variables with a "white working class" index characterized by political conservatism, rurality, and high percentages of white, evangelical Christian residents without college degrees. We find that the effectiveness of early social distancing measures decreased with higher values of this index. The results imply that the restrictions combined to slow the spread of COVID-19 by 12 percentage points per day in Kentucky's two largest urban counties but had no statistically detectable effect across the rest of the state., Competing Interests: The authors have declared that no competing interests exist.

This paper examines the role physical activity plays in determining body mass using data from the American Time Use Survey. Our work is the first to address the measurement error that arises when time use during a single day-rather than average daily time use over an extended period-is used as an explanatory variable. We show that failing to account for day-to-day variation in activities results in the effects of time use on a typical day being understated. Furthermore, we account for the possibility that physical activity and body mass are jointly determined by implementing Lewbel's instrumental variables estimator that exploits first-stage heteroskedasticity rather than traditional exclusion restrictions. While averaging 30 min of transportation-related biking or walking per day lowers the BMI of men by 1.5, we find no effect of physically active leisure on the BMI of men in our sample. In contrast, 30 min of per day of either type of physical activity lowers the BMI of women by 1., (Copyright © 2020. Published by Elsevier B.V.)

The 2016 US presidential election created uncertainty about the future of the Affordable Care Act (ACA) and led to postponed implementation of certain provisions, reduced funding for outreach, and the removal of the individual mandate tax penalty. In this article, we estimate how the causal impact of the ACA on insurance coverage changed during 2017 through 2019, the first 3 years of the Trump administration, compared to 2016. Data come from the 2011-2019 waves of the American Community Survey (ACS), with the sample restricted to non-elderly adults. Our model leverages variation in treatment intensity from state Medicaid expansion decisions and pre-ACA uninsured rates. We find that the coverage gains from the components of the law that took effect nationally-such as the individual mandate and regulations and subsidies in the private non-group market-fell from 5 percentage points in 2016 to 3.6 percentage points in 2019. In contrast, the coverage gains from the Medicaid expansion increased in 2017 (7.0 percentage points) before returning to the 2016 level of coverage gains in 2019 (5.9 percentage points). The net effect of the ACA in expansion states is a combination of these trends, with coverage gains falling from 10.8 percentage points in 2016 to 9.6 percentage points in 2019.

Objective: To estimate the impact of the major components of the ACA (Medicaid expansion, subsidized Marketplace plans, and insurance market reforms) on health care access and self-assessed health during the first 2 years of the Trump administration (2017 and 2018)., Data Source: The 2011-2018 waves of the Behavioral Risk Factor Surveillance System (BRFSS), with the sample restricted to nonelderly adults. The BRFSS is a commonly used data source in the ACA literature due to its large number of questions related to access and self-assessed health. In addition, it is large enough to precisely estimate the effects of state policy interventions, with over 300 000 observations per year., Design: We estimate difference-in-difference-in-differences (DDD) models to separately identify the effects of the private and Medicaid expansion portions of the ACA using an identification strategy initially developed in Courtemanche et al (2017). The differences come from: (a) time, (b) state Medicaid expansion status, and (c) local area pre-2014 uninsured rates. We examine ten outcome variables, including four measures of access and six measures of self-assessed health. We also examine differences by income and race/ethnicity., Principal Findings: Despite changes in ACA administration and the political debate surrounding the ACA during 2017 and 2018, including these fourth and fifth years of postreform data suggests continued gains in coverage. In addition, the improvements in reported excellent health that emerged with a lag after ACA implementation continued during 2017 and 2018., Conclusions: While gains in access and self-assessed health continued in the first 2 years of the Trump administration, the ongoing debate at both the federal and state level surrounding the future of the ACA suggests the need to continue monitoring how the law impacts these and many other important outcomes over time., (© 2020 The Authors. Health Services Research published by Wiley Periodicals LLC on behalf of Health Research and Educational Trust.)

State and local governments imposed social distancing measures in March and April 2020 to contain the spread of the novel coronavirus disease (COVID-19). These measures included bans on large social gatherings; school closures; closures of entertainment venues, gyms, bars, and restaurant dining areas; and shelter-in-place orders. We evaluated the impact of these measures on the growth rate of confirmed COVID-19 cases across US counties between March 1, 2020, and April 27, 2020. An event study design allowed each policy's impact on COVID-19 case growth to evolve over time. Adoption of government-imposed social distancing measures reduced the daily growth rate of confirmed COVID-19 cases by 5.4 percentage points after one to five days, 6.8 percentage points after six to ten days, 8.2 percentage points after eleven to fifteen days, and 9.1 percentage points after sixteen to twenty days. Holding the amount of voluntary social distancing constant, these results imply that there would have been ten times greater spread of COVID-19 by April 27 without shelter-in-place orders (ten million cases) and more than thirty-five times greater spread without any of the four measures (thirty-five million cases). Our article illustrates the potential danger of exponential spread in the absence of interventions, providing information relevant to strategies for restarting economic activity.

As of June 2020, the coronavirus pandemic has led to more than 2.3 million confirmed infections and 121 thousand fatalities in the USA, with starkly different incidence by race and ethnicity. Our study examines racial and ethnic disparities in confirmed COVID-19 cases across six diverse cities-Atlanta, Baltimore, Chicago, New York City, San Diego, and St. Louis-at the ZIP code level (covering 436 "neighborhoods" with a population of 17.7 million). Our analysis links these outcomes to six separate data sources to control for demographics; housing; socioeconomic status; occupation; transportation modes; health care access; long-run opportunity, as measured by income mobility and incarceration rates; human mobility; and underlying population health. We find that the proportions of Black and Hispanic residents in a ZIP code are both positively and statistically significantly associated with COVID-19 cases per capita. The magnitudes are sizeable for both Black and Hispanic, but even larger for Hispanic. Although some of these disparities can be explained by differences in long-run opportunity, human mobility, and demographics, most of the disparities remain unexplained even after including an extensive list of covariates related to possible mechanisms. For two cities-Chicago and New York-we also examine COVID-19 fatalities, finding that differences in confirmed COVID-19 cases explain the majority of the observed disparities in fatalities. In other words, the higher death toll of COVID-19 in predominantly Black and Hispanic communities mostly reflects higher case rates, rather than higher fatality rates for confirmed cases., Competing Interests: Conflict of InterestThe authors declare that they have no conflict of interest., (© Springer Nature Switzerland AG 2020.)

Objectives: To examine the association between changes in contextual economic factors on childhood obesity in the US., Methods: We combined data from 2003, 2007, and 2011/2012 National Surveys of Children's Health for 129,781 children aged 10-17 with 27 state-level variables capturing general economic conditions, labor supply, and the monetary or time costs of calorie intake, physical activity, and cigarette smoking. We employed regression models controlling for demographic factors and state and year fixed effects. We also examined heterogeneity in economic effects by household income., Results: Obesity risk increased with workforce proportion in blue-collar occupations, urban sprawl, female labor force participation, and number of convenience stores but declined with median household income, smoking ban in restaurants, and full service restaurants per capita. Most effects were specific to low income households, except for density of supercenters/warehouse clubs which was significantly associated with higher overweight/obesity risk only in higher income households., Conclusions for Practice: Changes in state-level economic factors related to labor supply and monetary or time cost of calorie intake may affect childhood obesity especially for children in low-income households. Policymakers should consider these effects when designing programs aimed at reducing childhood obesity.

This study contributes to the literature on the capacity challenges faced by health care providers after insurance expansions by examining the Affordable Care Act (ACA) and ambulance response times. Exploiting temporal and geographic variation in the implementation of the ACA as well as pre-treatment differences in uninsured rates, we estimate that the expansions of private and Medicaid coverage under the ACA combined to slow ambulance response times by an average of 24%. We conclude that, through extending coverage to individuals who, in its absence, would not have availed themselves of emergency medical services, the ACA added strain to emergency response systems., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Importance: Expanding insurance coverage may be associated with overuse of medical care because newly insured patients are insulated from having to pay the full cost., Objective: To examine the use of ambulance transport before and after the rollout of the Patient Protection and Affordable Care Act (ACA) in New York City (NYC), New York., Design, Setting, and Participants: In this case-control study, the volume of ambulance dispatches in NYC for minor injuries before and after the rollout of the ACA was examined. Data were drawn from a census of all ambulance dispatches in NYC between January 1, 2013, and July 31, 2016. Ambulance dispatches for more severe injuries, which are more difficult to characterize as unnecessary, were used as the control group. Analyses were conducted from August 17, 2017, to May, 10, 2019., Main Outcome and Measures: The main outcome was the number of ambulance dispatches for minor injuries, defined per month per dispatch zone. The implementation of the ACA was measured using an indicator variable of 1 for dispatches starting January 1, 2014, and 0 for dispatches before January 1, 2014. The number of ambulance dispatches for injuries and major injuries was used to account for secular trends. Injury severity was classified by the dispatchers based on information from the 911 callers with a severity score on a scale of 1 to 8, where 1 is the most severe; minor injuries had a score of 7; injuries, 5; and major injuries, 3., Results: There were 4 787 180 ambulance dispatches in NYC during the study. After the 2014 expansion of insurance coverage under the ACA, there was an increase in ambulance dispatches for minor injuries compared with dispatches for more severe injuries. Compared with the preimplementation mean (SD) of 20.75 (14.24) minor injury dispatches per dispatch zone per month, there were 7.71 (95% CI, 1.23-14.19) additional minor injury dispatches per dispatch zone per month compared with dispatches for other types of injuries, an increase of 37.2%. Given that NYC has 31 dispatch zones, this increase is equivalent to approximately 239 additional dispatches per month or 2868 additional dispatches per year for minor injuries., Conclusions and Relevance: There was a significant increase in use of ambulance transport for minor injuries in NYC after the ACA insurance expansion, suggesting that the change in health insurance structure was associated with increased use of emergency medical services in nonemergent situations. Future reforms to the US health insurance system should take into account the potential for increased use of emergency medical services in nonemergent situations, which the literature suggests may lead to congestion and slower response times.

Objective: To estimate the impact of the major components of the ACA (Medicaid expansion, subsidized Marketplace plans, and insurance market reforms) on disparities in insurance coverage after three years., Data Source: The 2011-2016 waves of the American Community Survey (ACS), with the sample restricted to nonelderly adults., Design: We estimate a difference-in-difference-in-differences model to separately identify the effects of the nationwide and Medicaid expansion portions of the ACA using the methodology developed in the recent ACA literature. The differences come from time, state Medicaid expansion status, and local area pre-ACA uninsured rates. In order to focus on access disparities, we stratify our sample separately by income, race/ethnicity, marital status, age, gender, and geography., Principal Findings: After three years, the fully implemented ACA eliminated 43% of the coverage gap across income groups, with the Medicaid expansion accounting for this entire reduction. The ACA also reduced coverage disparities across racial groups by 23%, across marital status by 46%, and across age-groups by 36%, with these changes being partly attributable to both the Medicaid expansion and nationwide components of the law., Conclusions: The fully implemented ACA has been successful in reducing coverage disparities across multiple groups., (© 2018 The Authors. Health Services Research published by Wiley Periodicals, Inc. on behalf of Health Research and Educational Trust.)

Using data from the Behavioral Risk Factor Surveillance System, we examine the causal impact of the Affordable Care Act on health-related outcomes after 3 years. We estimate difference-in-difference-in-differences models that exploit variation in treatment intensity from 2 sources: (1) local area prereform uninsured rates from 2013 and (2) state participation in the Medicaid expansion. Including the third postreform year leads to 2 important insights. First, gains in health insurance coverage and access to care from the policy continued to increase in the third year. Second, an improvement in the probability of reporting excellent health emerged in the third year, with the effect being largely driven by the non-Medicaid expansions components of the policy.

This paper aims to identify the causal effect of smoking on body mass index (BMI) using data from the Lung Health Study, a randomized trial of smoking cessation treatments. Since nicotine is a metabolic stimulant and appetite suppressant, quitting or reducing smoking could lead to weight gain. Using randomized treatment assignment to instrument for smoking, we estimate that quitting smoking leads to an average long-run weight gain of 1.8-1.9 BMI units, or 11-12 pounds at the average height. Semi-parametric models provide evidence of a diminishing marginal effect of smoking on BMI, while subsample regressions show that the impact is largest for younger individuals, those with no college degree, and those in the lowest quartile of baseline BMI., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The most significant pieces of the Affordable Care Act (exchanges, subsidies, Medicaid expansion, and individual mandate), implemented in 2014, were associated with sizable gains in coverage nationally that were divided equally between gains in Medicaid and private coverage. These national trends mask heterogeneity in gains by state Medicaid expansion status, age, income level, and source of coverage. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

We propose a new method for using validation data to correct self-reported weight and height in surveys that do not measure respondents. The standard correction in prior research regresses actual measures on reported values using an external validation dataset, and then uses the estimated coefficients to predict actual measures in the primary dataset. This approach requires the strong assumption that the expectations of measured weight and height conditional on the reported values are the same in both datasets. In contrast, we use percentile ranks rather than levels of reported weight and height. Our approach requires the weaker assumption that the conditional expectations of actual measures are increasing in reported values in both samples. This makes our correction more robust to differences in measurement error across surveys as long as both surveys represent the same population. We examine three nationally representative datasets and find that misreporting appears to be sensitive to differences in survey context. When we compare predicted BMI distributions using the two validation approaches, we find that the standard correction is affected by differences in misreporting while our correction is not. Finally, we present several examples that demonstrate the potential importance of our correction for future econometric analyses and estimates of obesity rates., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: Rank county health using a Bayesian factor analysis model., Data Sources: Secondary county data from the National Center for Health Statistics (through 2007) and Behavioral Risk Factor Surveillance System (through 2009)., Study Design: Our model builds on the existing county health rankings (CHRs) by using data-derived weights to compute ranks from mortality and morbidity variables, and by quantifying uncertainty based on population, spatial correlation, and missing data. We apply our model to Wisconsin, which has comprehensive data, and Texas, which has substantial missing information., Data Collection Methods: The data were downloaded from www.countyhealthrankings.org., Principal Findings: Our estimated rankings are more similar to the CHRs for Wisconsin than Texas, as the data-derived factor weights are closer to the assigned weights for Wisconsin. The correlations between the CHRs and our ranks are 0.89 for Wisconsin and 0.65 for Texas. Uncertainty is especially severe for Texas given the state's substantial missing data., Conclusions: The reliability of comprehensive CHRs varies from state to state. We advise focusing on the counties that remain among the least healthy after incorporating alternate weighting methods and accounting for uncertainty. Our results also highlight the need for broader geographic coverage in health data., (© Health Research and Educational Trust.)

Invasive aspergillosis (IA) is a major problem in the immunocompromised population, and its diagnosis is difficult due to the low sensitivity of available tests. Detection of Aspergillus nucleic acid by polymerase chain reaction (PCR) in serum samples is a promising diagnostic tool; however, use of multiple "in-house" methods precludes standardization. The first commercial PCR assay, MycAssay Aspergillus (Myconostica, Ltd), became available recently, and its performance in the diagnosis of IA was evaluated and compared with the galactomannan (GM) assay. Serum samples obtained from patients with hematological cancer were tested retrospectively with MycAssay Aspergillus PCR. Per-episode and per-test analyses were undertaken with 146 sera from 35 hematological patients. Sixteen patients had proven or probable IA and 19 had possible or no IA. In per-episode analysis, MycAssay Aspergillus had a sensitivity of 43.8% (95% confidence interval [CI], 19.8%-70.1%) and a specificity of 63.2% (95% CI, 38.4%-83.7%) for IA diagnosis. In per-test analyses, MycAssay Aspergillus had a lower specificity than the GM assay (83.3% vs. 93.1%, P = 0.04). The addition of PCR to routine clinical practice would have permitted the diagnosis of one additional probable IA in our cohort. Use of PCR instead of GM assay would have delayed the diagnosis in two cases. Aspergillus DNA detection by PCR with serum specimens using MycAssay showed a lower specificity than the GM assay and was associated with a low sensitivity for IA diagnosis. More studies are needed to determine the exact role of MycAssay in IA diagnosis in patients with hematological malignancy., (© The Author 2014. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Since Brazil's adoption of universal health care in 1988, the country's health care system has consisted of a mix of private providers and free public providers. We test whether income-based disparities in medical visits and medications remain in Brazil despite universal coverage using a nationally representative sample of over 48,000 households. Additional income is associated with less public sector utilisation and more private sector utilisation, both using simple correlations and regressions controlling for household characteristics and local area fixed effects. Importantly, the increase in private care use is greater than the drop in public care use. Also, income and unmet medical needs are negatively associated. These results suggest that access limitations remain for low-income households despite the availability of free public care.

Ambulatory surgery centers (ASCs) are small (typically physician owned) healthcare facilities that specialize in performing outpatient surgeries and therefore compete against hospitals for patients. Physicians who own ASCs could treat their most profitable patients at their ASCs and less profitable patients at hospitals. This paper asks if the profitability of an outpatient surgery impacts where a physician performs the surgery. Using a sample of Medicare patients from the National Survey of Ambulatory Surgery, we find that higher profit surgeries do have a higher probability of being performed at an ASC compared to a hospital. After controlling for surgery type, a 10% increase in a surgery's profitability is associated with a 1.2 to 1.4 percentage point increase in the probability the surgery is performed at an ASC., (Copyright © 2010 John Wiley & Sons, Ltd.)

I find evidence of a negative association between gasoline prices and body weight using a fixed effects model with several robustness checks. I also show that increases in gas prices are associated with additional walking and a reduction in the frequency with which people eat at restaurants, explaining their effect on weight. My estimates imply that 8% of the rise in obesity between 1979 and 2004 can be attributed to the concurrent drop in real gas prices, and that a permanent $1 increase in gasoline prices would reduce overweight and obesity in the United States by 7% and 10%.

This paper estimates the effect of ambulatory surgical centers (ASCs) on hospital surgical volume using hospital and year fixed effects models with several robustness checks. We show that ASC entry only appears to influence a hospital's outpatient surgical volume if the facilities are within a few miles of each other. Even then, the average reduction in hospital volume is only 2-4%, which is not nearly large enough to offset the new procedures performed by an entering ASC. The effect is, however, stronger for large ASCs and the first ASCs to enter a market. Additionally, we find no evidence that entering ASCs reduce a hospital's inpatient surgical volume., (Copyright 2010 Elsevier B.V. All rights reserved.)

Background: Polyomavirus associated nephropathy (PVAN) is an important cause of graft failure in the renal transplant population. It has been shown that viremia precedes PVAN, suggesting that measurement of blood viral load could be used for PVAN screening., Objectives: To verify the utility of BK virus (BKV) blood viral load measurement for PVAN screening in the renal transplant population, establish a threshold value, and determine the sensitivity and specificity of the test., Study Design: We developed a real-time PCR assay for BKV blood viral load measurement and included this assay in the PVAN screening protocol of the renal transplant recipients of our institution. We report results for 60 patients who had a blood viral load measurement concomitantly with an allograft biopsy with immunohistochemistry for polyomavirus., Results: 14 patients were found to have a PVAN on allograft biopsy together with a viral load above 3.0x10(3)copies/ml. None of the patients with a viral load under 3.0x10(3)copies/ml had a PVAN on allograft biopsy. The area under the receiver operating characteristic (ROC) curve was 0.95 (95% CI: 0.91-1.00) and using a threshold value of 3.0x10(3)copies/ml yielded a sensitivity of 100% (95% CI: 76.8-100%) and a specificity of 89.6% (95% CI: 77.3-96.5%) for PVAN screening., Conclusions: BKV blood viral load measurement is sensitive and specific for PVAN screening when a threshold value is precisely determined.

Economists have begun to debate if the rise in cigarette prices in the U.S. in recent decades has contributed to the nation's rise in obesity, reaching conclusions that are surprisingly sensitive to specification. I show that allowing for the effect to occur gradually over several years leads to the conclusion that a rise in cigarette prices is actually associated with a long-run reduction in body mass index and obesity. This result is robust to the different methodologies used in the literature. I also provide evidence that indirect effects on exercise and food consumption may explain the counterintuitive result.

Background: The traditional method of pituitary tumor excision is transseptal microscopic excision; however, the transnasal transsphenoidal endoscopic approach has shown comparable results with the transseptal microscopic approach at some institutions. The objective of this study is to compare the two types of sellar and parasellar mass resection: transnasal transsphenoidal endoscopic excision versus transseptal microscopic excision., Methods: A retrospective cohort analysis was performed on subjects who were referred to a tertiary hospital for surgical management of sellar or parasellar masses. The two groups of patients either underwent a transnasal endoscopic approach with endoscopic excision or transseptal microscopic excision. Demographics, tumor characteristics, operative details, length of hospital stay, intraoperative and postoperative complications, level of postoperative pain, recurrence rate, use of computed tomography (CT) image guidance, and length of follow-up were gathered. The data between the two groups were then compared., Results: The analysis included 19 subjects who underwent endoscopic excision and 29 subjects who underwent transseptal microscopic excision. Null macroadenoma was the most common sellar mass followed by prolactinoma. There were no statistical differences in rates of perioperative complications and suprasellar or cavernous sinus invasion. Patients who underwent an endoscopic approach had shorter operative times, lower estimated blood loss, less lumbar drain use, less pain, and a shorter postoperative hospital stay (p < 0.05)., Conclusion: The two approaches show similar intraoperative characteristics and immediate complication rates. Transnasal transsphenoidal endoscopic excision is a reasonable alternative to the traditional method of sellar mass excision.

Folate is required for one-carbon transfer reactions and the formation of purines and pyrimidines for DNA and RNA synthesis. Deficiency of folate can lead to many clinical abnormalities, including macrocytic anemia, cardiovascular diseases, birth defects, and carcinogenesis. The nucleotide imbalance due to folate deficiency causes cell cycle arrest in the S phase and uracil misincorporation into DNA, which may result in DNA double-strand breaks during repair. The role of folate in the immune system has not been fully characterized. We cultured PHA-activated human T lymphocytes in varying concentrations of folate, and measured proliferation, cell cycle, apoptosis, uracil misincorporation, and proportions of Th cells (CD4(+)) and cytotoxic T (CD8(+)) cells. Folate deficiency reduced proliferation of T lymphocytes, induced cell cycle arrest in the S phase, induced apoptosis, and increased the level of uracil in DNA. Folate deficiency also increased the CD4(+) to CD8(+) ratio due to a marked reduction of CD8(+) cell proliferation. Folate or nucleoside repletion of folate-deficient cells rapidly restored T lymphocyte proliferation and normal cell cycle, reduced the DNA uracil content, and lowered the CD4(+) to CD8(+) ratio. These data suggest that folate status may affect the immune system by reducing the capacity of CD8(+) cells to proliferate in response to activation.

Folate deficiency leads to increased dUMP/dTMP ratios and uracil misincorporation into DNA, which may increase cancer risk. We improved a previously described gas chromatography-mass spectrometry (GC-MS) assay for uracil in DNA and validated the assay by analyzing the DNA-uracil content of normal, primary human lymphocytes that were cultured in 0-3000 nM folic acid. In addition, the effects of nucleoside mixtures T or TdCA (T, thymidine; A, adenosine; dC, deoxycytidine) were investigated. Over 4 consecutive days, the inter- and intraassay coefficients of variation (CVs) were 2.3-3.9 and 0.6-2.2%. Mean recovery was 99.4%. Oligonucleotides containing 100 pg of uracil yielded a mean uracil measurement of 110.1 pg (CV=2.7%). Cells grown in different concentrations of folate showed a bimodal response, with maximum DNA-uracil at 12 nM, and minima at 0 and 3000 nM folate. Extremely folate-deficient cells may incorporate less uracil because DNA synthesis is reduced. A wide response to folate deficiency was seen in cells from different donors, suggesting that genetic background plays a critical role in individual susceptibility to DNA damage and cancer risk. Unexpectedly, TdCA supplementation caused increased DNA-uracil (vs 3000 nM folate for 10 days, P > 0.05), probably due to the conversion of deoxycytidine to deoxyuridine by cytidine deaminase, leading to elevated dUMP/dTMP ratios. This improved uracil assay could serve as a useful tool in the study of the mechanism of uracil misincorporation into DNA. The assay requires 3 microg of DNA per folate-deficient sample, but more may be required for baseline DNA-uracil detection in healthy humans.

The fetoprotein transcription factor (FTF) gene was inactivated in the mouse, with a lacZ gene inserted inframe into exon 4. LacZ staining of FTF+/- embryos shows that the mFTF gene is activated at initial stages of zygotic transcription. FTF gene activity is ubiquitous at the morula and blastocyst stages and then follows expression patterns indicative of multiple FTF functions in fetal development. FTF-/- embryos die at E6.5-7.5, with features typical of visceral endoderm dysfunction. Adult FTF+/- mice are hypocholesterolemic, and express liver FTF at about 40% of the normal level. Overexpression of liver FTF in transgenic mice indicates in vivo that FTF is an activator of CYP7A1. However, CYP7A1 expression is increased in FTF+/- liver. Gene expression profiles indicate that higher CYP7A1 expression is caused by attenuated liver cell stress signaling. Diet experiments support a model where FTF is quenched both by activated c-Jun, and by SHP as a stronger feedback mechanism to repress CYP7A1. A DR4 element is conserved in the FTF gene promoter and activated by LXR-RXR and TR-RXR, qualifying the FTF gene as a direct metabolic sensor. Liver FTF increases in rats treated with thyroid hormone or a high cholesterol diet. The FTF DR4 element tightens functional links between FTF and LXRalpha in cholesterol homeostasis and can explain transient surges of FTF gene activities during development and FTF levels lower than predicted in FTF+/- liver. The FTF-lacZ mouse establishes a central role for FTF in developmental, nutritive, and metabolic functions from early embryogenesis through adulthood.

DNA double-strand breaks, the most serious DNA lesion caused by ionizing radiation, are also caused by several vitamin or mineral deficiencies, such as for folate. Primary human lymphocytes were either irradiated or cultured at different levels of folate deficiency to assess cell proliferation, apoptosis, cell cycle, DNA breaks, and changes in gene expression. Both radiation and folate deficiency decreased cell proliferation and induced DNA breaks, apoptosis, and cell cycle arrest. Levels of folate deficiency commonly found resulted in effects similar to those caused by 1 Gy of radiation, a relatively high dose. Though both radiation and folate deficiency caused DNA breaks, they affected the expression of different genes. Radiation activated excision and DNA double-strand break repair genes and repressed mitochondrially encoded genes. Folate deficiency activated base and nucleotide excision repair genes and repressed folate-related genes. No DNA double-strand break repair gene was activated by folate deficiency. These findings suggest that a diet poor in folate may pose a risk of DNA damage comparable to that of a relatively high dose of radiation. Our results also suggest that research on biological effects of low-dose radiation should take into account the nutritional status of the subjects, because folate deficiency could confound the effects of low-dose radiation.

Poor zinc nutrition may be an important risk factor in oxidant release and the development of DNA damage and cancer. Approximately 10% of the United States population ingests <50% of the recommended daily allowance for zinc, a cofactor in proteins involved in antioxidant defenses, electron transport, DNA repair and p53 protein expression. This study examined the effects of zinc deficiency on oxidative stress, DNA damage and the expression of DNA repair enzymes in primary human lung fibroblasts by the use of DNA microarrays and functional assays. Cellular zinc was depleted by 1) growing cells in a zinc-deficient medium and 2) exposuring cells to an intracellular zinc chelator, N,N,N',N'-tetrakis-(2-pyridylmethyl)ethylenediamine. Array data revealed upregulation of genes involved in oxidative stress and DNA damage/repair and downregulation of other DNA repair genes. Zinc deficiency in cells caused an increase in oxidant production (dichlorofluoroscein fluorescence) and a significant induction of single-strand breaks (Comet assay) and p53 protein expression (Western blot analysis). Thus, zinc deficiency not only caused oxidative stress and DNA damage, but also compromised the cells' ability to repair this damage. Zinc adequacy appears to be necessary for maintaining DNA integrity and may be important in the prevention of DNA damage and cancer.

Cyclooxygenase-2 (COX-2)-catalyzed synthesis of prostaglandin E(2) (PGE(2)) plays a key role in inflammation and its associated diseases, such as cancer and vascular heart disease. Here we report that gamma-tocopherol (gammaT) reduced PGE(2) synthesis in both lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and IL-1beta-treated A549 human epithelial cells with an apparent IC(50) of 7.5 and 4 microM, respectively. The major metabolite of dietary gammaT, 2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), also exhibited an inhibitory effect, with an IC(50) of approximately 30 microM in these cells. In contrast, alpha-tocopherol at 50 microM slightly reduced (25%) PGE(2) formation in macrophages, but had no effect in epithelial cells. The inhibitory effects of gammaT and gamma-CEHC stemmed from their inhibition of COX-2 activity, rather than affecting protein expression or substrate availability, and appeared to be independent of antioxidant activity. gamma-CEHC also inhibited PGE(2) synthesis when exposed for 1 h to COX-2-preinduced cells followed by the addition of arachidonic acid (AA), whereas under similar conditions, gammaT required an 8- to 24-h incubation period to cause the inhibition. The inhibitory potency of gammaT and gamma-CEHC was diminished by an increase in AA concentration, suggesting that they might compete with AA at the active site of COX-2. We also observed a moderate reduction of nitrite accumulation and suppression of inducible nitric oxide synthase expression by gammaT in lipopolysaccharide-treated macrophages. These findings indicate that gammaT and its major metabolite possess anti-inflammatory activity and that gammaT at physiological concentrations may be important in human disease prevention.

Shuttle vector-based systems are extensively employed to study the mutational properties of various mutagens in mammalian cells. Such vectors are designed for the detection of point mutations, that is small deletions and single base and tandem substitutions. However, mutant target genes carrying two or more point mutations, referred to as multiple mutations, can also be found in various proportions depending on the mutagen and the cells used. To evaluate the frequency and characteristics of multiple mutations, we used a system where the plasmid, pYZ289, was treated by ultraviolet irradiation, aflatoxin B(1) or (+/-)-7 beta,8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene before transfection into mouse fibroblast cells. The kinds of mutations and the mutational spectra were different for single and multiple mutations. In addition, in at least 75% of the cases, mutations of multiples appeared to arise in the same strand. Furthermore, mutational spectra for multiple mutations were different for 5' and 3' members of multiple sets. These observations suggest that multiple mutations arise via a different mechanism than single mutations. Moreover, these findings suggest that multiples arise during translesion DNA synthesis and involve an error-prone polymerase able to introduce a base opposite misinstructive or noninstructional DNA lesions and subject to subsequent misincorporation errors.

p53 has been postulated to be the guardian of the genome. However, results supporting the prediction that point mutation frequencies are elevated in p53-deficient cells either have not been forthcoming or have been equivocal. To analyse the effect of p53 on point mutation frequency, we used the supF gene of the pYZ289 shuttle vector as a mutagenic target. pYZ289 was treated in vitro by ultraviolet irradiation, aflatoxin B1, (+/-)7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene and meta-chloroperoxybenzoic acid and then transfected into p53-deficient cells with or without a p53 expression vector. p53 reduced the mutant frequency up to fivefold when pYZ289 was treated with aflatoxin B1, (+/-)7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene or meta-chloroperoxybenzoic acid but not when it was ultraviolet-irradiated. The p53-dependent mutation frequency reduction was higher at a higher level of premutational lesions for aflatoxin B1 and (+/-)7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene and at a lower level of lesions for meta-chloroperoxybenzoic acid. This suggests that the chemical mutagens produce, in a dose-dependent fashion, two kinds of DNA damage, one subject to p53-dependent mutation frequency reduction and the other not. These results indicate that p53 can reduce the point mutation frequency in a shuttle vector treated by chemical mutagens and suggest that p53 can act as guardian of the genome for at least some kinds of point mutations.