University of Houston

About: University of Houston is a education organization based out in Houston, Texas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 23074 authors who have published 53903 publications receiving 1641968 citations.

Open "Back Door" in a Molecular Dynamics Simulation of Acetylcholinesterase

Abstract: The enzyme acetylcholinesterase generates a strong electrostatic field that can attract the cationic substrate acetylcholine to the active site. However, the long and narrow active site gorge seems inconsistent with the enzyme's high catalytic rate. A molecular dynamics simulation of acetylcholinesterase in water reveals the transient opening of a short channel, large enough to pass a water molecule, through a thin wall of the active site near tryptophan-84. This simulation suggests that substrate, products, or solvent could move through this "back door," in addition to the entrance revealed by the crystallographic structure. Electrostatic calculations show a strong field at the back door, oriented to attract the substrate and the reaction product choline and to repel the other reaction product, acetate. Analysis of the open back door conformation suggests a mutation that could seal the back door and thus test the hypothesis that thermal motion of this enzyme may open multiple routes of access to its active site.

New tricks for an old measure: The development of the Barratt Impulsiveness Scale–Brief (BIS-Brief).

Abstract: The Barratt Impulsivity Scale (BIS), a 30-item self-report measure, is one of the most commonly used scales for the assessment of the personality construct of impulsiveness. It has recently marked 50 years of use in research and clinical settings. The current BIS-11 is held to measure 3 theoretical subtraits, namely, attentional, motor, and non-planning impulsiveness. We evaluated the factor structure of the BIS using full information item bifactor analysis for Likert-type items. We found no evidence supporting the 3-factor model. In fact, half of the items do not share any relation with other items and do not form any factor. In light of this, we introduce a unidimensional Barratt Impulsiveness Scale-Brief (BIS-Brief) that includes 8 of the original BIS-11 items. Next, we present evidence of construct validity comparing scores obtained with the BIS-Brief against the original BIS total scores using data from (a) a community sample of borderline personality patients and normal controls, (b) a forensic sample, and (c) an inpatient sample of young adults and adolescents. We demonstrated similar indices of construct validity that is observed for the BIS-11 total score with the BIS-Brief score. Use of the BIS-Brief in clinical assessment settings and large epidemiological studies of psychiatric disorders will reduce the burden on respondents without loss of information. (PsycINFO Database Record (c) 2012 APA, all rights reserved). Language: en

Marital adjustment, parental disagreements about child rearing, and behavior problems in boys: Increasing the specificity of the marital assessment.

Abstract: 2 studies were conducted to illustrate how measuring a specific aspect of marriage, namely, child-rearing disagreements, provides a better understanding of the link between marriage and boys' behavior. In Study 1, 200 mothers of 3-year-old boys completed unstandardized measures of marital functioning and child behavior. An index of child-rearing disagreements: (1) correlated with a greater variety of behavior problems than nonchild disagreements, and (2) improved upon the prediction of behavior problems after accounting for nonchild disagreements as well as after accounting for boys' exposure to marital conflict. In Study 2, 87 mothers with 4-6-year-old sons completed the index of child-rearing disagreements used in Study 1 as well as standard measures of marital functioning and child behavior. Child-rearing disagreements: (1) predicted a greater variety of behavior problems than global marital adjustment, and (2) improved upon the prediction of internalizing problems after controlling for global marital adjustment as well as after controlling for boys' exposure to marital conflict.

Exploring Ethylene/Polar Vinyl Monomer Copolymerizations Using Ni and Pd α-Diimine Catalysts

Abstract: ConspectusThe most ubiquitous polymer, polyethylene (PE), is produced either through a radical-initiated process or, more commonly, through a coordination/insertion process employing early transition metal catalysts, particularly titanium- and chromium-based systems. These oxophilic early metal catalysts are not functional-group-tolerant and thus cannot be used to synthesize copolymers of ethylene and polar vinyl monomers such as alkyl acrylates and vinyl acetate. Such PE copolymers have enhanced properties relative to PE and are made through radical polymerization processes, requiring exceptionally high pressures and temperatures. Copolymerizations of polar vinyl monomers with ethylene using more functional group-tolerant late metal catalysts potentially offer an attractive alternative for generating such value-added copolymers since ligand variations may provide more control of polymer microstructures and milder reaction conditions would apply. This Account describes our efforts, particularly through de...