DeMixSC: a deconvolution framework that uses single-cell sequencing plus a small benchmark dataset for improved analysis of cell-type ratios in complex tissue samples.

Bulk deconvolution with single-cell/nucleus RNA-seq data is critical for understanding heterogeneity in complex biological samples, yet the technological discrepancy across sequencing platforms limits deconvolution accuracy. To address this, we introduce an experimental design to match inter-platform biological signals, hence revealing the technological discrepancy, and then develop a deconvolution framework called DeMixSC using the better-matched, i.e., benchmark, data. Built upon a novel weighted nonnegative least-squares framework, DeMixSC identifies and adjusts genes with high technological discrepancy and aligns the benchmark data with large patient cohorts of matched-tissue-type for large-scale deconvolution. Our results using a benchmark dataset of healthy retinas suggest much-improved deconvolution accuracy. Further analysis of a cohort of 453 patients with age-related macular degeneration supports the broad applicability of DeMixSC. Our findings reveal the impact of technological discrepancy on deconvolution performance and underscore the importance of a well-matched dataset to resolve this challenge. The developed DeMixSC framework is generally applicable for deconvolving large cohorts of disease tissues, and potentially cancer.

Perceived prevalence of peer marijuana use: changes among college students before and after Oregon recreational marijuana legalization.

Background: Oregon students' rates of marijuana use have increased following recreational marijuana legalization (RML), but the relation between RML and students' perceived peer use of marijuana - or descriptive norms - is unknown. Objectives: This study examined whether perceived peer use of marijuana changed more following RML for college students in Oregon than in states without RML. Methods: Repeated cross-sectional data were collected from the National College Health Assessment-II surveys from 2008 to 2016 to assess changes in descriptive norms ("Within the last 30 days, what percent of students at your school used marijuana?") among 18-26 year-old undergraduates from two Oregon institutions and 123 institutions in non-RML states (N = 280,006; 66.23% female; 33.19% male) following Oregon RML (7/1/2015). Mixed-effects regressions were used to account for clustering at the institutional level; models controlled for covariates and secular changes in descriptive norms. Results: RML was associated with higher perceived rates of marijuana use by peers [Percent Increase = 3.09, p < .001]. The effect was significant for respondents who had never used marijuana [Percent Increase = 3.72, p < .001], but not for respondents who recently or ever previously used marijuana. Respondents who had recently used marijuana had higher descriptive norms than those who had never used [Percent Increase = 12.83, p < .001]. Conclusions: Given the association between descriptive norms and personal use, RML-related increases in descriptive norms among non-using students could contribute to future marijuana use initiation and may be one mechanism linking RML with higher rates of marijuana use among college students.

Oregon recreational marijuana legalization: Changes in undergraduates' marijuana use rates from 2008 to 2016.

There have been few studies of marijuana use before and after recreational marijuana legalization (RML) in affected states. We tested whether marijuana use rates increased more among college students in Oregon than in non-RML states following Oregon RML in July 2015. Repeated cross-sectional National College Health Assessment-II surveys were completed by random samples of students within participating colleges from 2008 to 2016. Data were from 4-year institutions that participated both before and after Oregon RML. Undergraduates (ages 18-26 years) from 2 institutions in Oregon (n = 7,412) and 123 institutions (n = 274,340) in non-RML U.S. states self-reported use of marijuana, tobacco, alcohol, and other drugs in the past 30 days. Mixed-effects regressions accounted for clustering of participants within institutions and controlled for individual-, context-, and institution-level factors as well as secular changes in substance use rates from 2008 to 2016. Following RML, Oregon students (compared to non-RML-state students) showed relative increases in rates of marijuana use (odds ratio [OR] = 1.29, 95% confidence interval [CI: 1.13, 1.48], p = .0002, and decreases in tobacco use rates (OR = .71, 95% CI [.60, .85], p < .0001). Changes in marijuana use after RML did not differ significantly for participants under and over age 21 years. Some study limitations would be addressed with higher survey response rates, inclusion of other Oregon institutions, and controls for marijuana and other substance policies. Still, findings are consistent with an effect of RML on rates of marijuana use among young adult college students, which may have important public health implications. (PsycINFO Database Record