Ab-initio prediction of the electronic and optical excitations in polythiophene: isolated chains versus bulk polymer

We calculate the electronic and optical excitations of polythiophene using the GW approximation for the electronic self-energy, and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. Two different situations are studied: excitations on isolated chains and excitations on chains in crystalline polythiophene. The dielectric tensor for the crystalline situation is obtained by modeling the polymer chains as polarizable line objects, with a long-wavelength polarizability tensor obtained from the ab-initio polarizability function of the isolated chain. With this model dielectric tensor we construct a screened interaction for the crystalline case, including both intra- and interchain screening. In the crystalline situation both the quasi-particle band gap and the exciton binding energies are drastically reduced in comparison with the isolated chain. However, the optical gap is hardly affected. We expect this result to be relevant for conjugated polymers in general.Comment: 15 pages including 4 figures; to appear in Phys. Rev. B, 6/15/200

Interaction between COMT rs5993883 and second generation antipsychotics is linked to decreases in verbal cognition and cognitive control in bipolar disorder

Abstract Background Second generation antipsychotics (SGAs) are increasingly utilized in Bipolar Disorder (BD) but are potentially associated with cognitive side effects. Also linked to cognitive deficits associated with SGA-treatment are catechol-O-methyltransferase (COMT) gene variants. In this study, we examine the relationship between cognition in SGA use and COMT rs5993883 in cohort sample of subjects with BD. Methods Interactions between SGA-treatment and COMT rs5993883 genotype on cognition was tested using a battery of neuropsychological tests performed in cross-sectional study of 246 bipolar subjects. Results The mean age of our sample was 40.15 years and was comprised of 70 % female subjects. Significant demographic differences included gender, hospitalizations, benzodiazepine/antidepressant use and BD-type diagnosis. Linear regressions showed that the COMT rs5993883 GG genotype predicted lower verbal learning (p = 0.0006) and memory (p = 0.0026) scores, and lower scores on a cognitive control task (p = 0.004) in SGA-treated subjects. Interestingly, COMT GT- or TT-variants showed no intergroup cognitive differences. Further analysis revealed an interaction between SGA-COMT GG-genotype for verbal learning (p = 0.028), verbal memory (p = 0.026) and cognitive control (p = 0.0005). Conclusions This investigation contributes to previous work demonstrating links between cognition, SGA-treatment and COMT rs5993883 in BD subjects. Our analysis shows significant associations between cognitive domains such as verbal-cognition and cognitive control in SGA-treated subjects carrying the COMT rs5993883 GG-genotype. Prospective studies are needed to evaluate the clinical significance of these findings.http://deepblue.lib.umich.edu/bitstream/2027.42/134550/1/40359_2016_Article_118.pd

Effects of Drug Abuse and Mental Disorders on Use and Type of Antiretroviral Therapy in HIV-infected Persons

OBJECTIVE: To distinguish the effects of drug abuse, mental disorders, and problem drinking on antiretroviral therapy (ART) and highly active ART (HAART) use. DESIGN: Prospective population-based probability sample of 2,267 (representing 213,308) HIV-infected persons in care in the United States in early 1996. MEASUREMENTS: Self-reported ART from first (January 1997–July 1997) to second (August 1997–January 1998) follow-up interviews. Drug abuse/dependence, severity of abuse, alcohol use, and probable mental disorders assessed in the first follow-up interview. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) estimated from weighted models for 1) receipt of any ART, and 2) receipt of HAART among those on ART. RESULTS: Of our study population, ART was reported by 90% and HAART by 61%. Over one third had a probable mental disorder and nearly half had abused any drugs, but drug dependence (9%) or severe abuse (10%) was infrequent. Any ART was less likely for persons with dysthymia (AOR, 0.74; CI, 0.58 to 0.95) but only before adjustment for drug abuse. After full adjustment with mental health and drug abuse variables, any ART was less likely for drug dependence (AOR, 0.58; CI, 0.34 to 0.97), severe drug abuse (AOR, 0.52; CI, 0.32 to 0.87), and HIV risk from injection drug use (AOR, 0.55; CI, 0.39 to 0.79). Among drug users on ART, only mental health treatment was associated with HAART (AOR, 1.57; CI, 1.11 to 2.08). CONCLUSIONS: Drug abuse-related factors were greater barriers to ART use in this national sample than mental disorders but once on ART, these factors were unrelated to type of therapy

Electrophysiological Endophenotypes for Schizophrenia

Endophenotypes are quantitative, heritable traits that may help to elucidate the pathophysiologic mechanisms underlying complex disease syndromes, such as schizophrenia. They can be assessed at numerous levels of analysis; here, we review electrophysiological endophenotypes that have shown promise in helping us understand schizophrenia from a more mechanistic point of view. For each endophenotype, we describe typical experimental procedures, reliability, heritability, and reported gene and neurobiological associations. We discuss recent findings regarding the genetic architecture of specific electrophysiological endophenotypes, as well as converging evidence from EEG studies implicating disrupted balance of glutamatergic signaling and GABA-ergic inhibition in the pathophysiology of schizophrenia. We conclude that refining the measurement of electrophysiological endophenotypes, expanding genetic association studies, and integrating datasets are important next steps for understanding the mechanisms that connect identified genetic risk loci for schizophrenia to the disease phenotype