Calorimetric Analysis Using DNA Thermal Stability to determine protein concentration

It was recently reported for two globular proteins and a short DNA hairpin in NaCl buffer that values of the transition heat capacities, Cp,DNA and Cp,PRO for equal concentrations (mg/mL) of DNA and proteins, are essentially equivalent (differ by less than 1%). Additional evidence for this equivalence is presented that reveals this phenomenon does not depend on DNA sequence, buffer salt, or Tm. Sequences of two DNA hairpins were designed to confer a near 20°C difference in their Tm’s. For the molecules, in NaCl and CsCl buffer the evaluated Cp,PRO and Cp,DNA were equivalent. Based on the equivalence of transition heat capacities, a calorimetric method was devised to determine protein concentrations in pure and complex solutions. The scheme uses direct comparisons between the thermodynamic stability of a short DNA hairpin standard of known concentration, and thermodynamic stability of protein solutions of unknown concentrations. In all cases, evaluated protein concentrations determined from the DNA standard curve agreed with the UV-Vis concentration for monomeric proteins. For samples of multimeric proteins, streptavidin (tetramer), Herpes Simplex Virus glycoprotein D (trimer/dimer), and a 16 base pair DNA duplex (dimer), evaluated concentrations were greater than determined by UV-Vis by factors of 3.94, 2.65, and 2.15, respectively

Self-Regulation Shift Theory: A Dynamic Personal Agency Approach to Recovery Capital and Methodological Suggestions

Recovery capital highlights person and environmental resources associated with overcoming significant life challenges. This paper utilizes social cognitive theory as a framework for understanding how recovery capital functions in trauma adaptation. This theory outlines the bidirectional, dynamic interactions among person (e.g., cognitive and affective), behavioral (e.g., problem focused coping), and environmental variables (i.e., triadic reciprocal determinism). The value of this approach to understanding human adaptation to trauma is that it targets the self-regulatory processes that unfold for trauma survivors as they attempt to put their lives back together. Self-regulation shift theory (SRST), as an extension to social cognitive theory, is offered to explain how self-regulation is involved in both positive and negative adjustment. The theory uses a dynamical systems approach and highlights the mechanisms related to non-linear shifts in both positive and negative trauma recovery. According to SRST, trauma recovery may not be linear with threshold shifts (i.e., bifurcations) from one organized state (broken self) to another (empowered self). Coping self-efficacy perceptions are a critical factor influencing these threshold shifts. This paper concludes with a brief review of study designs and analytic procedures that can facilitate the application of non-linear dynamic research in this area

Microscopic formulation of the Zimm-Bragg model for the helix-coil transition

A microscopic spin model is proposed for the phenomenological Zimm-Bragg model for the helix-coil transition in biopolymers. This model is shown to provide the same thermophysical properties of the original Zimm-Bragg model and it allows a very convenient framework to compute statistical quantities. Physical origins of this spin model are made transparent by an exact mapping into a one-dimensional Ising model with an external field. However, the dependence on temperature of the reduced external field turns out to differ from the standard one-dimensional Ising model and hence it gives rise to different thermophysical properties, despite the exact mapping connecting them. We discuss how this point has been frequently overlooked in the recent literature.Comment: 11 pages, 2 figure

Social cognitive theory of posttraumatic recovery: The role of perceived self-efficacy. Behav Res Ther

Abstract The present article integrates findings from diverse studies on the generalized role of perceived coping self-efficacy in recovery from different types of traumatic experiences. They include natural disasters, technological catastrophes, terrorist attacks, military combat, and sexual and criminal assaults. The various studies apply multiple controls for diverse sets of potential contributors to posttraumatic recovery. In these different multivariate analyses, perceived coping self-efficacy emerges as a focal mediator of posttraumatic recovery. Verification of its independent contribution to posttraumatic recovery across a wide range of traumas lends support to the centrality of the enabling and protective function of belief in one's capability to exercise some measure of control over traumatic adversity.

Multiplex SNP Discrimination

Multiplex hybridization reactions of perfectly matched duplexes and duplexes containing a single basepair mismatch (SNPs) were investigated on DNA microarrays. Effects of duplex length, G-C percentage, and relative position of the SNP on duplex hybridization and SNP resolution were determined. Our theoretical model of multiplex hybridization accurately predicts observed results and implicates target concentration as a critical variable in multiplex SNP detection

Competition for hydrogen bond formation in the helix-coil transition and protein folding

The problem of the helix-coil transition of biopolymers in explicit solvents, like water, with the ability for hydrogen bonding with solvent is addressed analytically using a suitably modified version of the Generalized Model of Polypeptide Chains. Besides the regular helix-coil transition, an additional coil-helix or reentrant transition is also found at lower temperatures. The reentrant transition arises due to competition between polymer-polymer and polymer-water hydrogen bonds. The balance between the two types of hydrogen bonding can be shifted to either direction through changes not only in temperature, but also by pressure, mechanical force, osmotic stress or other external influences. Both polypeptides and polynucleotides are considered within a unified formalism. Our approach provides an explanation of the experimental difficulty of observing the reentrant transition with pressure; and underscores the advantage of pulling experiments for studies of DNA. Results are discussed and compared with those reported in a number of recent publications with which a significant level of agreement is obtained.Comment: 21 pages, 3 figures, submitted to Phys Rev

The association of exposure, risk, and resiliency factors with PTSD among Jews and Arabs exposed to repeated acts of terrorism in Israel

Israel has faced ongoing terrorism since the beginning of the Al Aqsa Intifada in September 2000. The authors examined risk and resiliency factors associated with posttraumatic stress disorder (PTSD) among 1,117 Jews and 394 Arab adult citizens of Israel during August and September 2004 through telephone interviews. Probable PTSD was found among 6.6% of Jews and 18.0% of Arabs. Predictors of probable PTSD in a multivariate model for Jews were refusal to report income, being traditionally religious, economic and psychosocial resource loss, greater traumatic growth, and lower social support. For Arabs, predictors were low education and economic resource loss among those exposed to terrorism. Findings for only those directly exposed to terrorism were similar to those for the overall national sample.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58032/1/20307_ftp.pd

DNA multiplex hybridization on microarrays and thermodynamic stability in solution: a direct comparison

Hybridization intensities of 30 distinct short duplex DNAs measured on spotted microarrays, were directly compared with thermodynamic stabilities measured in solution. DNA sequences were designed to promote formation of perfect match, or hybrid duplexes containing tandem mismatches. Thermodynamic parameters ΔH°, ΔS° and ΔG° of melting transitions in solution were evaluated directly using differential scanning calorimetry. Quantitative comparison with results from 63 multiplex microarray hybridization experiments provided a linear relationship for perfect match and most mismatch duplexes. Examination of outliers suggests that both duplex length and relative position of tandem mismatches could be important factors contributing to observed deviations from linearity. A detailed comparison of measured thermodynamic parameters with those calculated using the nearest-neighbor model was performed. Analysis revealed the nearest-neighbor model generally predicts mismatch duplexes to be less stable than experimentally observed. Results also show the relative stability of a tandem mismatch is highly dependent on the identity of the flanking Watson–Crick (w/c) base pairs. Thus, specifying the stability contribution of a tandem mismatch requires consideration of the sequence identity of at least four base pair units (tandem mismatch and flanking w/c base pairs). These observations underscore the need for rigorous evaluation of thermodynamic parameters describing tandem mismatch stability

Schools in the shadow of terrorism: Psychosocial adjustment and interest in interventions following terror attacks

Following terrorist events, teachers and nonteaching school personnel are important in helping children recover, yet little is known about their willingness to assist with this. We surveyed 399 employees from a Washington, D.C.-area school district following terror attacks (September 11, 2001, attacks; sniper shootings) about their exposure, adjustment, interest, and involvement in psychosocial interventions. Between 10% and 27% experienced one or more symptoms of posttraumatic stress (depending on category of symptom) in the month prior to the survey. Regression analyses revealed that peritraumatic distress, behavior change, and posttraumatic growth predicted interest in information on psychosocial interventions. Feeling prepared, adaptively managing work responsibilities, and perceiving an increase in student problems were related to intervening with students. Implications for school preparedness are discussed. © 2010 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77430/1/20493_ftp.pd