Submicrometric lipobead-based fluorescence sensors for chloride ion measurements in aqueous solution

This paper describes the preparation and optimization of the analytical properties of fluorescence-based submicrometric chloride ion sensing lipobeads. Fluorescence sensing lipobeads are polystyrene nanoparticles that are coated with a phospholipid membrane that contains a fluorescent indicator for a targeted analyte. In this study, the halide-specific fluorescence dye, lucigenin, was immobilized into the phospholipid membrane of the lipobeads to enable chloride ion detection. The fluorescence intensity of lucigenin decreases with increasing chloride ion concentration due to dynamic quenching. Lipobeads that contained only lucigenin were ineffective as chloride ion sensors due to poor partition of the water-soluble lucigenin molecules into the phospholipid membrane and high leakage rate of immobilized lucigenin molecules to the aqueous solution. To stabilize the chloride ion sensing lipobeads we coimmobilized hexadecanesulfonate molecules into the phospholipid membrane. The formation of ion pairs between hexadecanesulfonate and lucigenin decreased the hydrophilicity of the dye, increased its partition rate into the membrane, increased the brightness of the particles, and significantly decreased the leakage rate of the hydrophobic ion pair from the membrane to the solution. To further improve their chloride ion sensitivity, we also immobilized the chloride ionophore [9] mercuracarborand-3 into the lipobead membrane. The study resulted in a unique submicrometric chloride ion sensor, which is suitable for chloride ion measurements in biological fluids.     

RF properties of a X-band hybrid photoinjector

An INFN-LNF/UCLA/SAPIENZA collaboration is developing a hybrid photoinjector in X-band. A hybrid photoinjector is a novel high brightness electron source that couples a standing wave cell cavity (acting as an RF gun) directly to a multi-cell travelling-wave structure. This configuration offers a number of advantages over the split standing wave/travelling-wave system. Most notably the reflected RF transient is almost completely suppressed, thus eliminating the need for a circulator and the bunch lengthening effect that occurs in the drift section of the split system. These properties allow scaling of the device to higher field and frequencies, which should dramatically improve beam brightness. The RF coupling between the standing and the traveling wave sections is accomplished in the fourth cell encountered by the beam, with the SW section electrically coupled to it on-axis. This mode of coupling is particularly advantageous, as it is accompanied by a 90° phase shift in the accelerating field, resulting in strong velocity bunching effects on the beam that reverse the usual bunch lengthening induced after the gun exit in standard 1.6 cell photoinjectors. In this scenario, from the beam dynamics point of view, it is seen that device may produce ten's of femtosecond beams at ∼3.5 MeV and the emittance compensation dynamics remains manageable even in the presence of strong compression. We present here a survey of the device characteristics. In particular we show the results of the electromagnetic simulations, a beam dynamics analysis related to the temperature tuning of the SW and TW section, and a RF characterization using bead pull and scattering coefficient measurements of a device prototype.     

The Neptune photoinjector

The RF photoinjector in the Neptune advanced accelerator laboratory, along with associated beam diagnostics, transport and phase-space manipulation techniques are described. This versatile injector has been designed to produce short-pulse electron beams for a variety of uses: ultra-short bunches for injection into a next-generation plasma beatwave acceleration experiment, space-charge dominated beam physics studies, plasma wake-field acceleration driver, plasma lensing, and free-electron laser microbunching techniques. The component parts of the photoinjector, the RF gun, photocathode drive laser systems, booster linac, RF system, chicane compressor, beam diagnostic systems, and control system, are discussed. The present status of photoinjector commissioning at Neptune is reviewed, and proposed experiments are detailed.     

Letters by Freud on experimental psychodynamics.

Offers the author's recall of a personal exchange with Freud when Rosenzweig was a young psychologist, a memory prompted by the article by L. T. Benjamin, Jr. and D. N. Dixon (see record 83-32709) which discussed Freud's characteristics as a correspondent in general. In letters on 2 separate occasions, the author remembers that Freud made a similar negative response to any attempts to explore psychoanalytic theory by laboratory methods. This exchange clearly underscored Freud's distrust of, if not opposition to, experimental approaches to the validation of his clinically derived concepts. These letters are reproduced elsewhere with commentary (S. Rosenzweig, 1985). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Injection and dynamics of accelerated beams

This paper is a summary of the discussions undertaken by the working group on injection and accelerated beam dynamics at the 1st ICFA Novel and Advanced Accelerator Workshop on Second Generation Plasma Accelerators. The second generation of work on plasma accelerators is aimed to bring the accelerated beams up to the quality needed for applications such as high-energy physics linear colliders. To begin, first generation, or proof-of-principle, experiments and concepts were reviewed. To map the work needed in the second generation of development, the demands of the applications were examined, and an improved framework for discussing the viability of plasma accelerators was constructed. In particular, the issues scaling applications to the short wavelengths characteristic of plasma accelerators was discussed, as was the appropriate characterization of the beam quality in these devices, and the connection between plasma accelerator and conventional accelerator design. Within this framework, the working group discussed electron sources and injectors, the effects of drive beam evolution on accelerated beam dynamics, this effects of nonlinear plasma wave fields on beam phase space, stochastic processes, spatial and temporal beam-plasma wave matching, and future second-generation experimental goals and techniques.     

Activation of Insulin Signaling by Botanical Products

Type 2 diabetes (T2D) is a worldwide health problem, ranked as one of the leading causes for severe morbidity and premature mortality in modern society. Management of blood glucose is of major importance in order to limit the severe outcomes of the disease. However, despite the impressive success in the development of new antidiabetic drugs, almost no progress has been achieved with regard to the development of novel insulin-sensitizing agents. As insulin resistance is the most eminent factor in the patho-etiology of T2D, it is not surprising that an alarming number of patients still fail to meet glycemic goals. Owing to its wealth of chemical structures, the plant kingdom is considered as an inventory of compounds exerting various bioactivities, which might be used as a basis for the development of novel medications for various pathologies. Antidiabetic activity is found in over 400 plant species, and is attributable to varying mechanisms of action. Nevertheless, relatively limited evidence exists regarding phytochemicals directly activating insulin signaling, which is the focus of this review. Here, we will list plants and phytochemicals that have been found to improve insulin sensitivity by activation of the insulin signaling cascade, and will describe the active constituents and their mechanism of action.     

Intracellular immunization of rhesus CD34+ hematopoietic progenitor cells with a hairpin ribozyme protects T cells and macrophages from simian immunodeficiency virus infection

Evaluation of candidate genes for stem cell gene therapy for acquired immunodeficiency syndrome (AIDS) has been limited by the difficulty of supporting in vitro T-cell differentiation of genetically modified hematopoietic progenitor cells. Using a novel thymic stromal culture technique, we evaluated the ability of a hairpin ribozyme specific for simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2) to inhibit viral replication in T lymphocytes derived from transduced CD34+ progenitor cells. Retroviral transduction of rhesus macaque CD34+ progenitor cells with a retroviral vector (p9456t) encoding the SIV-specific ribozyme and the selectable marker neomycin phosphotransferase in the presence of bone marrow stroma and in the absence of exogenous cytokines resulted in efficient transduction of both colony-forming units and long-term culture-initiating cells, with transduction efficiencies ranging between 21% and 56%. After transduction, CD34+ cells were cultured on rhesus thymic stromal culture (to support in vitro differentiation of T cells) or in the presence of cytokines (to support differentiation of macrophage-like cells). After expansion and selection with the neomycin analog G418, cells derived from transduced progenitor cells were challenged with SIV. CD4+ T cells derived from CD34+ hematopoietic cells transduced with the ribozyme vector p9456t were highly resistant to challenge with SIV, exhibiting up to a 500-fold decrease in SIV replication, even after high multiplicities of infection. Macrophages derived from CD34+ cells transduced with the 9456 ribozyme exhibited a comparable level of inhibition of SIV replication. These results show that a hairpin ribozyme introduced into CD34+ hematopoietic progenitor cells can retain the ability to inhibit AIDS virus replication after T-cell differentiation and support the feasibility of intracellular immunization of hematopoietic stem cells against infection with HIV and SIV. Protection of multiple hematopoietic lineages with the SIV-specific ribozyme should permit analysis of stem cell gene therapy for AIDS in the SIV/macaque model.     

Psychology and United Nations human rights efforts.

The American Psychological Association Council in February 1987 passed a resolution declaring that "the discipline of psychology, and the academic and professional activities of psychologists, are relevant for securing and maintaining human rights" and resolving that "the APA applauds the ongoing efforts of the United Nations to defend and protect human rights and undertakes to recommend the main UN human rights instruments and documents to the attention of its boards, committees, and membership at large." To help to implement this resolution, the present article first provides information about the development of human rights concepts and instruments; treaties and declarations concerning torture are used as examples, and the impact of these international agreements is shown in a recent history-making U.S. legal decision. Second, the article reviews APA human rights policies and actions and offers some conclusions about them. Third, it calls attention to a number of specific international statements of human rights that are relevant to psychology. Fourth, the article suggests some further steps that APA could take to implement its resolution. Finally, it provides references to sources that include the texts of the United Nations' human rights instruments and information about them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of opioid peptides on learning and memory processes in the chick.

Several experiments were conducted to examine the effects of intracranial injection of opioid peptides and antagonists on learning and memory in the chick. Pretraining injection of [leu–5]enkephalin and the selective delta receptor agonist [D-Pen–2,L-Pen–5]enkephalin (DPLPE) into the intermediate medial hyperstriatum ventrale (IMHV) produced impairment. ICI 174,864, a delta-selective antagonist, reversed the impairment produced by either [leu–5]enkephalin or DPLPE, results indicating that delta receptors may play a role in learning in the chick and suggesting that the impairment produced by [leu–5]enkephalin is mediated through delta opioid receptors. β-endorphin produced a naloxone-reversible impairment in performance, which suggests that this impairment is mediated by opioid receptors. Bilateral injection of β-endorphin into the IMHV produced impairment, as did unilateral injection into the right, but not left, IMHV. Only bilateral injections into IMHV of [leu–5]enkephalin were effective. These results suggest that the effects of β-endorphin are centrally mediated whereas the effects of [leu–5]enkephalin may be localized to other brain regions or are peripherally mediated. These initial results suggest that opioids are associated with learning and memory in the chick. (PsycINFO Database Record (c) 2010 APA, all rights reserved)