Functional Analysis of the Dictyostelium discoideum Rho GTPases RacH and RacA

In this study, we investigated the functions of the two Rho GTPases RacA and RacH in Dictyostelium discoideum. Both genes are constitutively expressed and mRNA and protein are present throughout the complete developmental cycle of Dictyostelium. RacA belongs to the subfamily of Rho BTB proteins that are characterised by a modular organisation, consisting of a GTPase domain, a praline-rich region, a tandem of two BTB domains and a C-terminal region of unknown function. Thus RacA promises to be both, a highly specific adaptor molecule thanks to its BTB domains, and a regulator of signal transduction due to its GTPase domain. The particularity about RacH is that, in contrast to the other characterised Rho GTPases residing at the plasma membrane, RacH was targeted to the nuclear envelope, ER and Golgi apparatus. The pivotal process regulated by Rho GTPases is the rearrangement of the actin cytoskeleton. Therefore we investigated the role of RacA and RacH in cytoskeleton-dependent processes by analysing the performance of the respective knock out mutants in processes depending on the re-organisation of the cortical actin cytoskeleton. RacA-KO cells show conditional defects when cultured in supension: they are severly impaired in growth, cytokinesis and cell shape probably due to lowered cortical tension and F-actin distribution and reveal a slight chemotactical defect as well as reduced rates of pino- and phagocytosis. Considering the correspondence in phenotypes of cells lacking either RacA, PAKa or myosin II and the PAKa-binding by RacA, a model in which RacA acts in concert with Rac1 GTPases as a regulator of PAKa activity working in parallel to the PI3-kinase/PKB pathway that elicits PAKa activity upon chemoattractant stimulation, is proposed. Moreover putative RacA binding partners have been identified. Cells deficient in RacH have a decreased rate of fluid phase endocytosis and exocytosis and a divergent performance in the endocytosis process in comparison to the WT, but no other apparent defects. In a cell-free system RacH stimulated actin polymerisation, suggesting that it might be involved in actin-based trafficking of vesicular compartments, more specifically in the delivery of cargo to early endosomes. The lack of RacH causes defective early endocytosis leading to defects also observed at later stages of this process. By means of chimeric constructs and alanine exchange mutants it was also shown that several regions of the molecule, not only the hypervariable region, determine targeting of RacH and that targeting to the correct membrane compartment probably makes interactions with appropriate regulators and effectors possible, and is therefore essential for function

Screening for depression and anxiety after stroke: Developing protocols for use in the community

Purpose: To develop screening protocols to detect depression and anxiety after stroke in a community setting and train therapists to administer them. Method: Psychologists and a community therapist met to design a system suitable for screening for anxiety and depression in all those with stroke, including people with cognitive and/or communication problems. Other therapists and a local user group were also consulted. Therapists were then trained in the use of the protocols. The ability to enact the protocols was assessed via case vignettes and staff experience, over a month-long trial. Results: It was considered appropriate for community therapists to screen patients and to do this within 4 weeks of first contact. Two protocols were designed, one for patients without significant communication/cognitive deficits and one for patients with these difficulties. Therapists applied the protocols with accuracy to the case vignettes and rated the training highly. No challenges in applying the protocols in the clinical setting were reported over an initial 1-month trial. Conclusion: Two protocols to screen for depression and anxiety after stroke have been developed. These appear feasible for use when trialled via case vignette and in clinical practice. Further research might consider the usefulness of the screens in detecting actual clinical disorder and developing better screens to identify anxiety after stroke, particularly in those with a cognitive and/or communication disorder. Implications for Rehabilitation Depression and anxiety are common after stroke and likely affect rehabilitation outcomes. These problems can be identified via screening protocols that include measures appropriate for use with those patients having significant cognitive and/or communication disabilities. Rehabilitation therapists can enact these protocols. © 2012 Informa UK, Ltd

Description of Multi Quasi Particle Bands by the Tilted Axis Cranking Model

The selfconsistent cranking approach is extended to the case of rotation about an axis which is tilted with respect to the principal axes of the deformed potential (Tilted Axis Cranking). Expressions for the energies and the intra bands electromagnetic transition probabilities are given. The mean field solutions are interpreted in terms of quantal rotational states. The construction of the quasiparticle configurations and the elimination of spurious states is discussed. The application of the theory to high spin data is demonstrated by analyzing the multi quasiparticle bands in the nuclide-s with $N=102,103$ and $Z=71,72,73$.Comment: 23 pages 27 figure

A one-dimensional lattice model for a quantum mechanical free particle

Two types of particles, A and B with their corresponding antiparticles, are defined in a one dimensional cyclic lattice with an odd number of sites. In each step of time evolution, each particle acts as a source for the polarization field of the other type of particle with nonlocal action but with an effect decreasing with the distance: A -->...\bar{B} B \bar{B} B \bar{B} ... ; B --> A \bar{A} A \bar{A} A ... . It is shown that the combined distribution of these particles obeys the time evolution of a free particle as given by quantum mechanics.Comment: 8 pages. Revte

Chemoenzymatic Synthesis and Chemical Recycling of Poly(ester-urethane)s

Novel poly(ester-urethane)s were prepared by a synthetic route using a lipase that avoids the use of hazardous diisocyanate. The urethane linkage was formed by the reaction of phenyl carbonate with amino acids and amino alcohols that produced urethane-containing diacids and hydroxy acids, respectively. The urethane diacid underwent polymerization with polyethylene glycol and α,ω-alkanediols and also the urethane-containing hydroxy acid monomer was polymerized by the lipase to produce high-molecular-weight poly(ester-urethane)s. The periodic introduction of ester linkages into the polyurethane chain by the lipase-catalyzed polymerization afforded chemically recyclable points. They were readily depolymerized in the presence of lipase into cyclic oligomers, which were readily repolymerized in the presence of the same enzyme. Due to the symmetrical structure of the polymers, poly(ester-urethane)s synthesized in this study showed higher Tm, Young’s modulus and tensile strength values

Evidence for octupole vibration in the triaxial superdeformed well of Lu164

High-spin states in Lu164 were populated in the Sb121(Ca48,5n) reaction at 215 MeV and γ-ray coincidences were measured with the Gammasphere spectrometer. Through this experiment the eight known triaxial superdeformed bands in Lu164 could be confirmed. Some of these bands were extended to higher as well as to lower spins. Evidence is reported for the first time for weak ΔI=1,E1 transitions linking TSD3 and TSD1. This observation may imply coupling to octupole vibrational degrees of freedom. The decay mechanism is different from the one observed in the neighboring even-N isotopes, which exhibit wobbling excitations built on the πi13/2 structure with E2(M1),ΔI=1 interband decay. An additional sequence decaying at high spin into TSD1 was observed up to Iπ=(50-). This band has a constant dynamic moment of inertia of ∼70 2MeV-1 and an alignment that is ∼2 larger than that found for TSD1. A revision of the assumed spin-parity-assignment of TSD2 is based on the observed decay-out to normal-deformed structures. The parity and signature quantum numbers of TSD2 are now firmly assigned as (π,α)=(+,0), in disagreement with the former assignment of (π,α)=(-,1), which was based on the assumption that TSD2 is the signature partner of TSD1. TSD1 and TSD2 show an alignment gain at ω∼0.67 and 0.60 MeV, respectively. In TSD1 the involvement of the j15/2 neutron orbital is suggested to be responsible for the high-frequency crossing

Understanding recovery in the context of lived experience of personality disorders: a collaborative, qualitative research study

Background Concepts of recovery increasingly inform the development and delivery of mental health services internationally. In the UK recent policy advocates the application of recovery concepts to the treatment of personality disorders. However diagnosis and understanding of personality disorders remains contested, challenging any assumption that mainstream recovery thinking can be directly translated into personality disorders services. Methods In a qualitative interview-based study understandings of recovery were explored in extended, in-depth interviews with six people purposively sampled from a specialist personality disorders’ service in the UK. An interpretive, collaborative approach to research was adopted in which university-, clinical- and service user (consumer) researchers were jointly involved in carrying out interviews and analysing interview data. Results Findings suggested that recovery cannot be conceptualised separately from an understanding of the lived experience of personality disorders. This experience was characterised by a complexity of ambiguous, interrelating and conflicting feelings, thoughts and actions as individuals tried to cope with tensions between internally and externally experienced worlds. Our analysis was suggestive of a process of recovering or, for some, discovering a sense of self that can safely coexist in both worlds. Conclusions We conclude that key facilitators of recovery – positive personal relationships and wider social interaction – are also where the core vulnerabilities of individuals with lived experience of personaility disorders can lie. There is a role for personality disorders services in providing a safe space in which to develop positive relationships. Through discursive practice within the research team understandings of recovery were co-produced that responded to the lived experience of personality disorders and were of applied relevance to practitioners

Collective and noncollective excitations in 122Te

High-spin states in 122Te were populated in the reaction 82Se(48Ca, α4n)122Te at a beam energy of 200 MeV and γ-ray coincidences were measured with the Gammasphere spectrometer. The previously known level scheme was extended to considerably higher spin. Maximally aligned states and several high-energy transitions feeding into some of these levels were observed. In addition, seven collective high-spin bands were discovered for the first time in this nucleus. The experimental results are compared with cranked Nilsson-Strutinsky model calculations and possible configuration assignments to the new high-spin structures are discussed

High-spin spectroscopy in Xe125

Levels excited up to 39.8 MeV and 119/2 units of angular momentum have been populated in Xe125 by the 82Se(Ca48,5n)Xe125 reaction. High-fold γ-ray coincidence events were measured using the Gammasphere Ge detector array. Nine regular rotational bands extending from levels identified previously up to almost 60ℏ have been identified, and three of these have been connected to low-lying levels having well-established spins and parities. Configurations have been assigned to six of the bands based on alignment properties, band crossings, and comparison with theoretical cranked shell model calculations (CSM). Transition quadrupole moments have been measured for these bands in the spin range 31-55ℏ and were found to be in agreement with the CSM calculations. The corresponding quadrupole deformation ε2 ranges from 0.28 to 0.34 at a γ deformation of 0° and from 0.29 to 0.36 at a γ value of 5°

Highly deformed high-spin band in 125I

High-spin states in 125I have been investigated using the reaction 82Se(48Ca,p4n) at a beam energy of 200 MeV and γ-ray coincidence events were detected using the Gammasphere spectrometer. A deformed rotational band, extending up to Iπ=95/2-, was observed for the first time in a heavier odd-A iodine nucleus. The characteristics of the band are very similar to those of the highly deformed bands observed recently in neighboring nuclei and it is essentially identical to one of the previously known bands in 126Xe. The experimental results are compared to cranked Nilsson-Strutinsky calculations and possible configurations for the band are discussed