The Neural Encoding of Cocaine-Induced Devaluation in The Ventral Pallidum

Cocaine experience affects motivation structures such as the nucleus accumbens (NAc) and its major output target, the ventral pallidum (VP). Previous studies demonstrated that both NAc activity and hedonic responses change reliably as a taste cue comes to predict cocaine availability. Here we extended this investigation to examine drug-experience induced changes in hedonic encoding in the VP. VP activity was first characterized in adult male Sprague–Dawley rats in response to intraoral infusions of palatable saccharin and unpalatable quinine solutions. Next, rats received 7 daily pairings of saccharin that predicted either a cocaine (20 mg/kg, ip) or saline injection. Finally, the responses to saccharin and quinine were again assessed. Of 109 units recorded in 11 rats that received saccharin–cocaine pairings, 71% of responsive units significantly reduced firing rate during saccharin infusions and 64% increased firing rate during quinine exposure. However, as saccharin came to predict cocaine, and elicited aversive taste reactivity, VP responses changed to resemble quinine. After conditioning, 70% of saccharin-responsive units increased firing rate. Most units that encoded the palatable taste (predominantly reduced firing rate) were located in the anterior VP, while most units that were responsive to aversive tastes were located in the posterior VP. This study reveals an anatomical complexity to the nature of hedonic encoding in the VP

Inhibition of productive/competitive endocytic pathways enhances siRNA delivery and cell specific targeting

While the use of short interfering RNAs (siRNAs) for laboratory studies is now common practice, development of siRNAs for therapeutic applications has slowed, due in part to a still limited understanding of the endocytosis and intracellular trafficking of siRNA-containing complexes. As a result, it is difficult to design delivery vehicles for specific cell types, resulting in inefficient delivery, cytotoxicity, or immunogenicity when used in vivo. Our aim is to identify which endocytosis and intracellular trafficking pathways lead to active silencing by siRNA-containing complexes. Our work explores the preferential mechanism of endocytosis (whether by clathrin, caveolin, Arf6, Graf1, flotillin, or macropinocytosis) across multiple cell types (HeLa (cervical), H1299 (lung), HEK293 (kidney), and HepG2 (liver)). Using Lipofectamine 2000 (LF2K), fluorescentlylabeled siRNAs were delivered to cells stably expressing green fluorescent protein (GFP). Chemical inhibitors (Filipin, Dynasore, Cytochalasin D, Chlorpromazine, Amiloride, and Methyl-β- cyclodextrin) were used to identify the specific endocytic pathway internalizing the complexes. By measuring the effect of inhibitors on both intracellular levels of siRNA and GFP silencing, we were able to categorize pathways as being productive/competitive according to their functional role in facilitating gene silencing. In productive pathways, siRNAs are actively delivered to a cell and silence a target protein, whereas in competitive pathways, siRNAs are endocytosed but do not lead to silencing. Please click Additional Files below to see the full abstract

Digital Literacy Learning In Higher Education Through Digital Storytelling Approach

It is necessary to develop digital literacy skills with which students can communicate and express their ideas effectively using digital media. The educational sectors around the world are beginning to incorporate digital literacy into the curriculum. Digital storytelling, one of the possible classroom activities, is an approach which may help engage and motivate students to learn digital literacy skills. To investigate this approach, the present small-scale study employs the methods including interviewing and analysing the artefacts of three students selected from a purposive sample on a multimedia course. The findings indicate that the three students have improved in terms of three aspects of digital literacy skills, namely, digital competence, digital usage and digital transformation regardless of their prior knowledge and levels of digital literacy.

Development and analytical performance evaluation of an automated chemiluminescent immunoassay for pro-gastrin releasing peptide (ProGRP)

Background: Pro-gastrin releasing peptide ( ProGRP) concentrations in blood play an important role in the diagnosis and treatment of patients with small cell lung cancer (SCLC). The automated quantitative ARCHITECT (R) ProGRP assay was developed to aid in the differential diagnosis and in the management of SCLC. The purpose of this study was to evaluate the analytical performance of this chemiluminescent microparticle immunoassay at multiple sites. Methods: ARCHITECT ProGRP measures ProGRP using a two-step sandwich using monoclonal anti-ProGRP antibodies coated on paramagnetic microparticles and labeled with acridinium. Analytical performance of the assay was evaluated at four sites: Abbott Japan, Denka Seiken, the Johns Hopkins University, and the University of Munich. Results: Total precision (%CV) for nine analyte concentrations was between 2.2 and 5.7. The analytical sensitivity of the assay was between 0.20 pg/mL and 0.88 pg/mL. The functional sensitivity at 20% CV was between 0.66 pg/mL and 1.73 pg/mL. The assay was linear up to 50,000 pg/mL using a 1:10 autodilution protocol. The calibration curve was stable for 30 days. Comparison with the Fujirebio microtiter plate enzyme-linked immunosorbent assay (EIA) ProGRP assay gave a slope of 0.93 and a correlation coefficient (r) of 0.99. Conclusions: These results demonstrate that the ARCHITECT ProGRP assay has excellent sensitivity, precision, and correlation to a reference method. This assay provides a convenient automated method for ProGRP measurement in serum and plasma in hospitals and clinical laboratories. Clin Chem Lab Med 2009;47:1557-63

Fixed-Horizon Temporal Difference Methods for Stable Reinforcement Learning

We explore fixed-horizon temporal difference (TD) methods, reinforcement learning algorithms for a new kind of value function that predicts the sum of rewards over a $\textit{fixed}$ number of future time steps. To learn the value function for horizon $h$, these algorithms bootstrap from the value function for horizon $h-1$, or some shorter horizon. Because no value function bootstraps from itself, fixed-horizon methods are immune to the stability problems that plague other off-policy TD methods using function approximation (also known as "the deadly triad"). Although fixed-horizon methods require the storage of additional value functions, this gives the agent additional predictive power, while the added complexity can be substantially reduced via parallel updates, shared weights, and $n$-step bootstrapping. We show how to use fixed-horizon value functions to solve reinforcement learning problems competitively with methods such as Q-learning that learn conventional value functions. We also prove convergence of fixed-horizon temporal difference methods with linear and general function approximation. Taken together, our results establish fixed-horizon TD methods as a viable new way of avoiding the stability problems of the deadly triad.Comment: AAAI 202

Energy Starved Candidatus Pelagibacter Ubique Substitutes Light-Mediated ATP Production for Endogenous Carbon Respiration

Previous studies have demonstrated that Candidatus Pelagibacter ubique, a member of the SAR11 clade, constitutively expresses proteorhodopsin (PR) proteins that can function as light-dependent proton pumps. However, exposure to light did not significantly improve the growth rate or final cell densities of SAR11 isolates in a wide range of conditions. Thus, the ecophysiological role of PR in SAR11 remained unresolved. We investigated a range of cellular properties and here show that light causes dramatic changes in physiology and gene expression in Cand. P. ubique cells that are starved for carbon, but provides little or no advantage during active growth on organic carbon substrates. During logarithmic growth there was no difference in oxygen consumption by cells in light versus dark. Energy starved cells respired endogenous carbon in the dark, becoming spheres that approached the minimum predicted size for cells, and produced abundant pili. In the light, energy starved cells maintained size, ATP content, and higher substrate transport rates, and differentially expressed nearly 10% of their genome. These findings show that PR is a vital adaptation that supports Cand. P. ubique metabolism during carbon starvation, a condition that is likely to occur in the extreme conditions of ocean environments

Thiol-yne \u27Click\u27 Chemistry As a Route to Functional Lipid Mimetics

Thiol-alkyne \u27click\u27 chemistry is a modular, efficient mechanism to synthesize complex A2B 3-arm star polymers. This general motif is similar to a phospholipid where the A blocks correspond to lypophilic chains and the B block represents the polar head group. In this communication we employ thiol-yne chemistry to produce polypeptide-based A2B lipid mimetics. The utility of the thiol-yne reaction is demonstrated by using a divergent and a convergent approach in the synthesis. These polymers self-assemble in aqueous solution into spherical vesicles with a relatively narrow size distribution independent of block composition over the range studied. Using the thiol-yne convergent synthesis, we envision a modular approach to functionalize proteins or oligopeptides with lipophilic chains that can imbed seamlessly into a cell membrane