Acute Dissociation and Cardiac Reactivity to Script-Driven Imagery in Trauma-Related Disorders

Background: Potential acute protective functions of dissociation include modulation of stress-induced psychophysiological arousal. This study was designed to explore whether acute dissociative reactions during a stress experiment would override the effects of reexperiencing. Methods: Psychophysiological reactions during exposure to script-driven trauma imagery were studied in relation to acute responses of reexperiencing and dissociative symptoms in 61 patients with histories of exposure to a variety of traumas. Acute symptomatic responses were assessed with the Responses to Script-Driven Imagery Scale (RSDI), and participants were divided into four groups by median splits of RSDI reexperiencing and dissociation subscale scores. Results: In a comparison of the high RSDI reexperiencing groups with low versus high acute dissociative symptoms, the high dissociators exhibited significantly lower heart rate (HR) during trauma script and a significantly smaller script-induced decrease in parasympathetic cardiac activity. HR reactivity to the trauma script was negatively correlated with acute dissociative symptom severity. Conclusions: Acute dissociative reactions are a potential moderator of response to experimental paradigms investigating psychologically traumatized populations. We therefore suggest that future research on psychophysiological stress reactions in traumatized samples should routinely assess for acute dissociative symptoms

Kinetics of the gas-phase reactions of chlorine atoms with CH 2 F 2 , CH 3 CCl 3 , and CF 3 CFH 2 over the temperature range 253–553 K

Relative rate techniques were used to study the title reactions in 930–1200 mbar of N 2 diluent. The reaction rate coefficients measured in the present work are summarized by the expressions k (Cl + CH 2 F 2 ) = 1.19 × 10 −17 T 2 exp(−1023/T) cm 3 molecule −1 s −1 (253–553 K), k (Cl + CH 3 CCl 3 ) = 2.41 × 10 −12 exp(−1630/T) cm 3 molecule −1 s −1 (253–313 K), and k (Cl + CF 3 CFH 2 ) = 1.27 × 10 −12 exp(−2019/T) cm 3 molecule −1 s −1 (253–313 K). Results are discussed with respect to the literature data. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 401–406, 2009Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62132/1/20398_ftp.pd

Addition of a chlorine atom to tetrachloroethylene

The gas-phase competitive photochlorination Cl2 + C 2Cl4 + 1,2-C2H4Cl2 has been studied at 310°K between 40 and 642 torr in the presence and absence of added CO2 and SF6. The results are explained in terms of a mechanism in which the activated C2Cl*5 radical initially formed by addition of a Cl atom to C2Cl4 is deactivated by collision much more rapidly than it can react. The experimental data, combined with those from a parallel study of the competition Cl 2 + C2Cl4 + C2H6 at 348°K and those from previous studies at higher temperatures, lead to the new values log10k2 (mole-1 l. sec-1) = 10.1 and log10k4 (sec-1) = 13.51-16080/4.576T. for the reactions Cl + C2Cl4 → 2C2Cl5 k2 and C2Cl 5 → 4C2Cl4 + Cl, k4 where C2Cl5 is a thermalized radical. These results, combined with known thermochemical data, yield: D(C2Cl 4-Cl) = 16.9, D(C2Cl5-H) = 95.8 and D(C 2Cl5-Cl) = 72.6 kcal mole-1, ΔH°f,298 (C2Cl5) = 8.4 kcal mole -1 and S°298 (C2Cl5) = 96.4 cal mole-1 deg.-1. The rate constant ka for the reaction C2Cl*5 → C2Cl4 + Cl is estimated to be less than 4 × 107 sec-1. Existing data on addition-substitution competitive photochlorinations of C 2H4, 1,2-C2H2Cl2, C 2HCl3 and C2Cl4 are discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Hydrogen abstraction from chlorinated ethanes by chlorine atoms

The hydrogen abstraction from the chlorinated ethanes by chlorine atoms has been investigated in the gas phase between 323 and 423°K. Absolute values of the rate constants have been obtained using a competition method with chloroform or methyl chloride as competitor. The activation energies and the pre-exponential factors are discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Oxygen-inhibited photochlorination of 1,2-dichloroethane

The oxygen‐inhibited photochlorination of 1,2‐dichloroethane has been studied in the gas‐phase between 321 and 489,5°K. The following rate constants have been estimated: (Formula Presented.) These results are compared to those observed for the reactions of C2H6, C2HCl5, C2HCl3 and C2Cl4. Copyright © 1972 Wiley‐VCH Verlag GmbH & Co. KGaA, WeinheimSCOPUS: ar.jinfo:eu-repo/semantics/publishe