Quantum dynamics in strong fluctuating fields

A large number of multifaceted quantum transport processes in molecular systems and physical nanosystems can be treated in terms of quantum relaxation processes which couple to one or several fluctuating environments. A thermal equilibrium environment can conveniently be modelled by a thermal bath of harmonic oscillators. An archetype situation provides a two-state dissipative quantum dynamics, commonly known under the label of a spin-boson dynamics. An interesting and nontrivial physical situation emerges, however, when the quantum dynamics evolves far away from thermal equilibrium. This occurs, for example, when a charge transferring medium possesses nonequilibrium degrees of freedom, or when a strong time-dependent control field is applied externally. Accordingly, certain parameters of underlying quantum subsystem acquire stochastic character. Herein, we review the general theoretical framework which is based on the method of projector operators, yielding the quantum master equations for systems that are exposed to strong external fields. This allows one to investigate on a common basis the influence of nonequilibrium fluctuations and periodic electrical fields on quantum transport processes. Most importantly, such strong fluctuating fields induce a whole variety of nonlinear and nonequilibrium phenomena. A characteristic feature of such dynamics is the absence of thermal (quantum) detailed balance.Comment: review article, Advances in Physics (2005), in pres

Use of cDNA Tiling Arrays for Identifying Protein Interactions Selected by In Vitro Display Technologies

In vitro display technologies such as mRNA display are powerful screening tools for protein interaction analysis, but the final cloning and sequencing processes represent a bottleneck, resulting in many false negatives. Here we describe an application of tiling array technology to identify specifically binding proteins selected with the in vitro virus (IVV) mRNA display technology. We constructed transcription-factor tiling (TFT) arrays containing ∼1,600 open reading frame sequences of known and predicted mouse transcription-regulatory factors (334,372 oligonucleotides, 50-mer in length) to analyze cDNA fragments from mRNA-display screening for Jun-associated proteins. The use of the TFT arrays greatly increased the coverage of known Jun-interactors to 28% (from 14% with the cloning and sequencing approach), without reducing the accuracy (∼75%). This method could detect even targets with extremely low expression levels (less than a single mRNA copy per cell in whole brain tissue). This highly sensitive and reliable method should be useful for high-throughput protein interaction analysis on a genome-wide scale

Measuring Resilience in Adult Women Using the 10-Items Connor-Davidson Resilience Scale (CD-RISC). Role of Trauma Exposure and Anxiety Disorders

International audiencePURPOSE: Resilience is the ability of individuals to adapt positively in the face of trauma. Little is known, however, about lifetime factors affecting resilience. METHODS: We assessed the effects of psychiatric disorder and lifetime trauma history on the resilience self-evaluation using the Connor-Davidson Resilience Scale (CD-RISC-10) in a high-risk-women sample. Two hundred and thirty eight community-dwelling women, including 122 participants in a study of breast cancer survivors and 116 participants without previous history of cancer completed the CD-RISC-10. Lifetime psychiatric symptoms were assessed retrospectively using two standardized psychiatric examinations (Mini International Neuropsychiatric Interview and Watson's Post-Traumatic Stress Disorder Inventory). RESULTS: Multivariate logistic regression adjusted for age, education, trauma history, cancer, current psychiatric diagnoses, and psychoactive treatment indicated a negative association between current psychiatric disorder and high resilience compared to low resilience level (OR = 0.44, 95% CI [0.21-0.93]). This was related to anxiety and not mood disorder. A positive and independent association with a trauma history was also observed (OR = 3.18, 95% CI [1.44-7.01]). CONCLUSION: Self-evaluation of resilience is influenced by both current anxiety disorder and trauma history. The independent positive association between resilience and trauma exposure may indicate a "vaccination" effect. This finding need to be taken into account in future studies evaluating resilience in general or clinical populations

Assay for ubiquitin ligase activity: High-throughput screen for inhibitors of HDM2

An assay for the autoubiquitination activity of the E3 ligase HDM2 (Mdm2) was developed and adapted to a high-throughput format to identify inhibitors of this activity. The assay can also be used to measure the activity of other E3s and may be useful in finding both inhibitors and activators of a wide range of different ubiquitin ligase

Inhibitors of ubiquitin-activating enzyme (E1), a new class of potential cancer therapeutics

The conjugation of proteins with ubiquitin plays numerous regulatory roles through both proteasomal-dependent and nonproteasomal-dependent functions. Alterations in ubiquitylation are observed in a wide range of pathologic conditions, including numerous malignancies. For this reason, there is great interest in targeting the ubiquitin-proteasome system in cancer. Several classes of proteasome inhibitors, which block degradation of ubiquitylated proteins, are widely used in research, and one, Bortezomib, is now in clinical use. Despite the well-defined and central role of the ubiquitin-activating enzyme (E1), no cell permeable inhibitors of El have been identified. Such inhibitors should, in principle, block all functions of ubiquitylation. We now report 4[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoic acid ethyl ester (PYR-41) as the first such inhibitor. Unexpectedly, in addition to blocking ubiquitylation, PYR-41 increased total sumoylation in cells. The molecular basis for this is unknown; however, increased sumoylation was also observed in cells harboring temperature-sensitive El. Functionally, PYR-41 attenuates cytokine-mediated nuclear factor-kappa B activation. This correlates with inhibition of nonproteasomal (Lys-63) ubiquitylation of TRAF6, which is essential to I kappa B kinase activation. PYR-41 also prevents the downstream ubiquitylation and proteasomal degradation of I kappa B alpha. Furthermore, PYR-41 inhibits degradation of p53 and activates the transcriptional activity of this tumor suppressor. Consistent with this, it differentially kills transformed p53-expressing cells. Thus, PYR-41 and related pyrazones provide proof of principle for the capacity to differentially kill transformed cells, suggesting the potential for E I inhibitors as therapeutics in cancer. These inhibitors can also be valuable tools for studying ubiquitylation