MyristoylCoA:protein N-Myristoyltransferase: Probing Host-Guest Interactions Using Synthetic Substrates

MyristoylCoA:protein N-myristoyl transferase (NMT) catalyzes the cotranslational covalent attachment of myristate (C14:0) to the ammo-terminal glycine residues of a variety of biologically important proteins. An extensive survey of myristic acid analogs has previously allowed us to infer the conformational constraints imposed upon the fatty acid when bound to the enzyme's acylCoA binding site. A series of myristic acid analogs has now been synthesized and studied in an in vitro assay to probe further the conformation of NMT's bound ligand and to assess the importance of the distance between the carboxyl and the proposed bend in the fatty acid.     

Characterisation of disulfide-bond dynamics in non-native states of lysozyme and its disulfide deletion mutants by NMR

This report describes NMR-spectroscopic investigations of the conformational dynamics of disulfide bonds in hen-egg-white lysozyme substitution mutants. The following four systems have been investigated: 2SS(alpha), a lysozyme variant that contains C64A, C76A, C80A and C94A substitutions, was studied in water at pH 2 and 3.8 and in urea (8 M, pH 2); 2SS(beta) lysozyme, which has C6S, C30A, C115A and C127A substitutions, was studied in water (pH 2) and urea (8 M, pH 2). The NMR analysis of heteronuclear 15N-relaxation rates shows that the barrier to disulfide-bond isomerisation can vary substantially in different lysozyme mutants and depends on the residual structure present in these states. The investigations reveal cooperativity in the modulation of micro- to millisecond dynamics that is due to the presence of multiple disulfide bridges in lysozyme. Mutation of cysteines in one of the two structural domains substantially diminishes the barrier to rotational isomerisation in the other domain. However, the interactions between hydrophobic clusters within and across the domains remains intact.     

Anodic stripping voltammetry enhancement by redox magnetohydrodynamics

The effect of an external magnetic field on linear scan anodic stripping voltammetry (ASV) in solutions of 10(-6)-10(-7) M concentrations of lead, cadmium, and copper at mercury films on glassy carbon electrodes has been investigated. A high concentration of Hg(2+) was added to the analyte solution to induce a large cathodic current during the deposition step. Therefore, a large Lorentz force from the net flux of charge through the magnetic field resulted in convection due to magnetohydrodynamics. The faster delivery of analytes to the mercury film electrode during deposition caused an increase in the anodic stripping peaks. The effect of varying Hg(2+) concentrations (0-60 mM) and magnetic field strengths (0-1.77 T) on the enhancement of the stripping peaks was investigated. Enhancements as large as 129% for peak currents and 167% for peak areas were observed. An enhancement of approximately 100% was observed when 60 mM Fe(3+) replaced high concentrations of Hg(2+). This method of convection exhibits promise for small-volume ASV analysis with possible improved limits of detection and decreased preconcentration times.     

Musculoskeletal kinematics during voluntary head tracking movements in primate

In this study we examined connections between vertebral motion and patterns of muscle activation during voluntary head tracking movements. A Rhesus(Macaca mulatto) monkey was trained to produce sinusoidal tracking movements of the head in the sagittal plane while seated. Radio-opaque markers were placed in the cervical vertebrae, and intramuscular patch electrodes were implanted to record from eight neck muscles. Videofluoroscopic images of cervical vertebral motion, and EMG (electromyographic) responses were simultaneously recorded. Experimental results demonstrated that head and vertebrae moved synchronously and that motion occurred primarily at skull-C₁, C₆-C₇ and C₇-T₁. Our findings illustrate that although the biomechanical constraints of each species may limit the number of solutions available, it is the task requirements that appear to govern CNS (central nervous system) selection of movement behaviors.     

Exercise adherence or maintenance among older adults: 1-year follow-up study.

Follow-up evaluation was conducted of 101 older men and women (mean age 67 yrs) who had participated in a randomized study of physiological and psychological effects of aerobic exercise. 85 Ss completed the follow-up evaluation, and almost all of them (94%) reported continuing with physical activity, as assessed by a self-report measure. Total energy expenditure was calculated as an indicator of exercise maintenance, and energy expenditure at follow-up was predicted from measures of physiological functioning, psychological well-being, and cognitive functioning obtained at the conclusion of the structured exercise program. Greater cardiorespiratory endurance, faster psychomotor speed, and lower anxiety predicted exercise behavior at follow-up, accounting for 13% of the variance in exercise behavior. Gender was not a significant predictor of exercise behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypnotic hypermnesia: Enhanced memory accessibility or report bias?

Laboratory studies of hypnotic hypermnesia have yielded inconsistent evidence of memory enhancement, and the process responsible for the occasional positive findings have eluded identification. The present experiment assessed delayed recall for filmed material under conditions in which subjects were required to answer all questions, by guessing if necessary. They also rated confidence in the accuracy of each response. After an initial wake-baseline forced-recall test, subjects were randomly assigned to hypnosis or waking conditions for a second forced-recall test. Both groups of subjects recalled additional correct details on the second test, but the magnitude of this hypermnesia was no greater for subjects exposed to the hypnosis treatment. Hypnotized subjects did, however, exhibit a significantly greater increase in confidence for responses designated as "guesses" on the prior waking test—a finding consistent with the view that hypnosis engenders a shift in the subjective criterion for what constitutes a "memory." Implications of these findings for the use of hypnosis in forensic situations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mothers' fantasy representations and infant security of attachment: A Rorschach study of first pregnancy.

Studied the relationship between pregnant women's fantasy representations on the Rorschach test and later attachment status of their 1-yr-olds. The Manual for Assessing Primary Process Manifestations in Rorschach Responses (R. R. Holt, 1968) was used to score Rorschach protocols gathered from 25 women during their 1st pregnancies. Later, the 1-yr-olds and their mothers were videotaped in the Strange Situation to assess infant attachment behaviors. Findings support the hypothesis that primary process integration during pregnancy is significantly and positively related to infant security of attachment. Results also suggest a relation between empathic maternal behaviors and dimensions of mothers' unconscious mental representations measurable prior to the infant's birth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery and verification of memories of childhood sexual trauma.

53 women outpatients (aged 15–53 yrs) participated in short-term therapy groups for incest survivors. This treatment modality proved to be a powerful stimulus for recovery of previously repressed traumatic memories. A relationship was observed between the age of onset, duration, and degree of violence of the abuse and the extent to which memory of the abuse had been repressed. 74% of Ss were able to validate their memories by obtaining corroborating evidence from other sources. The therapeutic function of recovering and validating traumatic memories is explored in relation to case material. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New chemical structural features of coal

An adaptation of the transalkylation reaction provides a means for cleaving alkyl substituants off of the aromatic portions of coal as well as extracting aliphatic connecting groups from between aromatic clusters. Using reasonably low concentrations of acid catalysts, the groups are transferred to an acceptor without modification or rearrangement and identified by means of convenient laboratory procedures. The catalyst in this procedure is trifluoromethanesulphonic acid and toluene is the acceptor. The reaction was performed on several samples of coal and gave toluene solutions containing a large number of derivatives. Results are reported for Wyodak coal. A list of substituents and several new connecting groups is recorded.