Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use.

Combined effect of individual and neighborhood socioeconomic status on mortality in patients with newly diagnosed dyslipidemia: A nationwide Korean cohort study from 2002 to 2013

BACKGROUND AND AIM

The study aims to determine whether dyslipidemia patients living in less affluent neighborhood are at a higher risk of mortality compared to those living in more affluent neighborhoods.

METHODS AND RESULTS

A population-based cohort study was conducted using a stratified representative sampling from the National Health Insurance claim data from 2002 to 2013. The target subjects comprise patients newly diagnosed with dyslipidemia receiving medication. We performed a survival analysis using the Cox proportional hazard model. Of 11,946 patients with dyslipidemia, 1053 (8.8%) subjects died during the follow-up period. Of the dyslipidemia patients earning a middle-class income, the adjusted HR in less affluent neighborhoods was higher than that in the more affluent neighborhoods compared to the reference category of high individual SES in more affluent neighborhoods (less affluent; hazard ratio (HR) = 1.64, 95% confidence interval (CI): 1.35-1.99 vs. more affluent; HR = 1.48, 95% CI: 1.20-1.81, respectively). We obtained consistent results in patients with lower income, wherein the adjusted HR in less affluent neighborhoods was higher than that in more affluent neighborhoods (less affluent; HR = 1.52, 95% CI: 1.16-1.97 vs. more affluent; HR = 1.41, 95% CI: 1.04-1.92, respectively).

CONCLUSION

Living in a less affluent neighborhood contributes to higher mortality among dyslipidemia patients. The individual- and neighborhood-level variables cumulatively affect individuals such that the most at-risk individuals include those having both individual- and neighborhood-level risk factors. These findings raise important clinical and public health concerns and indicate that neighborhood SES approaches should be essentially considered in health-care policies similar to individual SES.

Genetic influence on the association between bone mineral density and testosterone in Korean men

Low bone mineral density (BMD) leads to an increased risk of osteoporotic fracture. Total testosterone and free testosterone were positively associated with BMD, which was significantly influenced by the additive genetic effects.

INTRODUCTION

This cross-sectional study aimed to evaluate an association between testosterone and BMD and the influence of genetic factors on the association.

METHODS

Study subjects were 1070 Korean men including 144 pairs of monozygotic twins and their family members. Levels of serum total testosterone and sex hormone binding globulin (SHBG) were measured by chemiluminescence immunoassay. Calculated free testosterone (cFT) was then determined using Vermeulen's method. BMDs of the whole body and specific regions were measured using dual-energy X-ray absorptiometry.

RESULTS

Linear mixed regression analyses showed that total testosterone and cFT were positively associated with BMD at most regions, after considering intra-familial relationship and covariates including fat mass, lean mass, and SHBG. SHBG had an inverse association with BMD at the pelvis but not with the BMD at other regions after adjusting for all covariates and cFT. Co-twin control analysis in monozygotic twins found no association between pairwise difference of testosterone and pairwise difference of BMD. Bivariate variance component analysis showed that both total testosterone and cFT had a significant positive additive genetic correlation with BMD at rib, spine, and arm, whereas SHBG had no significant genetic correlation with BMD. Inverse environmental correlations were seen between total testosterone and BMDs at the lumbar spine and arm.

CONCLUSIONS

This Korean twin and family study showed that both total testosterone and free testosterone were positively associated with BMD and that genetic effects were significant on the association between testosterone and BMD.

Effect of oxygen pressure on structure and ionic conductivity of epitaxial Li0.33La0.55TiO3 solid electrolyte thin films produced by pulsed laser deposition

We report on the ionic conductivity of Li_0.33La_0.55TiO₃ (LLTO) epitaxial films grown on the (100) and (111) surfaces of single crystal SrTiO₃ (STO) substrates at different oxygen partial pressures (from 1.33 to 26.66 Pa).

Pediatric Intubation by Paramedics in a Large Emergency Medical Services System: Process, Challenges, and Outcomes

STUDY OBJECTIVE

Pediatric intubation is a core paramedic skill in some emergency medical services (EMS) systems. The literature lacks a detailed examination of the challenges and subsequent adjustments made by paramedics when intubating children in the out-of-hospital setting. We undertake a descriptive evaluation of the process of out-of-hospital pediatric intubation, focusing on challenges, adjustments, and outcomes.

METHODS

We performed a retrospective analysis of EMS responses between 2006 and 2012 that involved attempted intubation of children younger than 13 years by paramedics in a large, metropolitan EMS system. We calculated the incidence rate of attempted pediatric intubation with EMS and county census data. To summarize the intubation process, we linked a detailed out-of-hospital airway registry with clinical records from EMS, hospital, or autopsy encounters for each child. The main outcome measures were procedural challenges, procedural success, complications, and patient disposition.

RESULTS

Paramedics attempted intubation in 299 cases during 6.3 years, with an incidence of 1 pediatric intubation per 2,198 EMS responses. Less than half of intubations (44%) were for patients in cardiac arrest. Two thirds of patients were intubated on the first attempt (66%), and overall success was 97%. The most prevalent challenge was body fluids obscuring the laryngeal view (33%). After a failed first intubation attempt, corrective actions taken by paramedics included changing equipment (33%), suctioning (32%), and repositioning the patient (27%). Six patients (2%) experienced peri-intubation cardiac arrest and 1 patient had an iatrogenic tracheal injury. No esophageal intubations were observed. Of patients transported to the hospital, 86% were admitted to intensive care and hospital mortality was 27%.

CONCLUSION

Pediatric intubation by paramedics was performed infrequently in this EMS system. Although overall intubation success was high, a detailed evaluation of the process of intubation revealed specific challenges and adjustments that can be anticipated by paramedics to improve first-pass success, potentially reduce complications, and ultimately improve clinical outcomes.

Neural evidence that suspense narrows attentional focus

The scope of visual attention changes dynamically over time. Although previous research has reported conditions that suppress peripheral visual processing, no prior work has investigated how attention changes in response to the variable emotional content of audiovisual narratives. We used fMRI to test for the suppression of spatially peripheral stimuli and enhancement of narrative-relevant central stimuli at moments when suspense increased in narrative film excerpts. Participants viewed films presented at fixation, while flashing checkerboards appeared in the periphery. Analyses revealed that increasing narrative suspense caused reduced activity in peripheral visual processing regions in the anterior calcarine sulcus and in default mode network nodes. Concurrently, activity increased in central visual processing regions and in frontal and parietal regions recruited for attention and dynamic visual processing. These results provide evidence, using naturalistic stimuli, of dynamic spatial tuning of attention in early visual processing areas due to narrative context.

A framework for implementation of organ effect models in TOPAS with benchmarks extended to proton therapy

The aim of this work was to develop a framework for modeling organ effects within TOPAS (TOol for PArticle Simulation), a wrapper of the Geant4 Monte Carlo toolkit that facilitates particle therapy simulation. The DICOM interface for TOPAS was extended to permit contour input, used to assign voxels to organs. The following dose response models were implemented: The Lyman-Kutcher-Burman model, the critical element model, the population based critical volume model, the parallel-serial model, a sigmoid-based model of Niemierko for normal tissue complication probability and tumor control probability (TCP), and a Poisson-based model for TCP. The framework allows easy manipulation of the parameters of these models and the implementation of other models. As part of the verification, results for the parallel-serial and Poisson model for x-ray irradiation of a water phantom were compared to data from the AAPM Task Group 166. When using the task group dose-volume histograms (DVHs), results were found to be sensitive to the number of points in the DVH, with differences up to 2.4%, some of which are attributable to differences between the implemented models. New results are given with the point spacing specified. When using Monte Carlo calculations with TOPAS, despite the relatively good match to the published DVH's, differences up to 9% were found for the parallel-serial model (for a maximum DVH difference of 2%) and up to 0.5% for the Poisson model (for a maximum DVH difference of 0.5%). However, differences of 74.5% (in Rectangle1), 34.8% (in PTV) and 52.1% (in Triangle) for the critical element, critical volume and the sigmoid-based models were found respectively. We propose a new benchmark for verification of organ effect models in proton therapy. The benchmark consists of customized structures in the spread out Bragg peak plateau, normal tissue, tumor, penumbra and in the distal region. The DVH's, DVH point spacing, and results of the organ effect models are provided. The models were used to calculate dose response for a Head and Neck patient to demonstrate functionality of the new framework and indicate the degree of variability between the models in proton therapy.

Improved efficiency in Monte Carlo simulation for passive-scattering proton therapy

The aim of this work was to improve the computational efficiency of Monte Carlo simulations when tracking protons through a proton therapy treatment head. Two proton therapy facilities were considered, the Francis H Burr Proton Therapy Center (FHBPTC) at the Massachusetts General Hospital and the Crocker Lab eye treatment facility used by University of California at San Francisco (UCSFETF). The computational efficiency was evaluated for phase space files scored at the exit of the treatment head to determine optimal parameters to improve efficiency while maintaining accuracy in the dose calculation. For FHBPTC, particles were split by a factor of 8 upstream of the second scatterer and upstream of the aperture. The radius of the region for Russian roulette was set to 2.5 or 1.5 times the radius of the aperture and a secondary particle production cut (PC) of 50 mm was applied. For UCSFETF, particles were split a factor of 16 upstream of a water absorber column and upstream of the aperture. Here, the radius of the region for Russian roulette was set to 4 times the radius of the aperture and a PC of 0.05 mm was applied. In both setups, the cylindrical symmetry of the proton beam was exploited to position the split particles randomly spaced around the beam axis. When simulating a phase space for subsequent water phantom simulations, efficiency gains between a factor of 19.9  ±  0.1 and 52.21  ±  0.04 for the FHTPC setups and 57.3  ±  0.5 for the UCSFETF setups were obtained. For a phase space used as input for simulations in a patient geometry, the gain was a factor of 78.6  ±  7.5. Lateral-dose curves in water were within the accepted clinical tolerance of 2%, with statistical uncertainties of 0.5% for the two facilities. For the patient geometry and by considering the 2% and 2mm criteria, 98.4% of the voxels showed a gamma index lower than unity. An analysis of the dose distribution resulted in systematic deviations below of 0.88% for 20% of the voxels with dose of 20% of the maximum or more.