Plasticity in the Rat Prefrontal Cortex: Linking Gene Expression and an Operant Learning with a Computational Theory

The plasticity in the medial Prefrontal Cortex (mPFC) of rodents or lateral prefrontal cortex in non human primates (lPFC), plays a key role neural circuits involved in learning and memory. Several genes, like brain-derived neurotrophic factor (BDNF), cAMP response element binding (CREB), Synapsin I, Calcium/calmodulin-dependent protein kinase II (CamKII), activity-regulated cytoskeleton-associated protein (Arc), c-jun and c-fos have been related to plasticity processes. We analysed differential expression of related plasticity genes and immediate early genes in the mPFC of rats during learning an operant conditioning task. Incompletely and completely trained animals were studied because of the distinct events predicted by our computational model at different learning stages. During learning an operant conditioning task, we measured changes in the mRNA levels by Real-Time RT-PCR during learning; expression of these markers associated to plasticity was incremented while learning and such increments began to decline when the task was learned. The plasticity changes in the lPFC during learning predicted by the model matched up with those of the representative gene BDNF. Herein, we showed for the first time that plasticity in the mPFC in rats during learning of an operant conditioning is higher while learning than when the task is learned, using an integrative approach of a computational model and gene expression.     

Interaction of water-soluble porphyrins with single- and double-stranded polyribonucleotides

CD and uv-visible absorption studies with several tetracationic water-soluble porphyrin derivatives show that some of these species can serve as probes to discriminate between A- and B-conformational forms of single-stranded polynucleotides. It is also observed that these porphyrins can participate in the formation of double helices by forming transient intermediate complexes enroute to duplex formation. © 1994 John Wiley & Sons, Inc.     

Ergoline Derivatives as a Probe for Featuring the 5-HT1A Receptor Pharmacophore

A 5-HT_1A pharmacophore has been obtained employing a set of rigid templates encompassing the 5-HT1A structure. The use of rigid templates allowed us to overcome the discrepancy found when flexible structures where the energy of the active conformers are sometimes higher than the global minimum energy are used. On the basis of the results herein reported the three-dimensional requirements necessary for the binding interaction have been defined within this set of molecules. In this study forbidden zones of the receptor have been characterised. The pharmacophore model derived places some agonist/antagonist pharmacophore models appeared in the literature.     

Rank Diversity of Languages: Generic Behavior in Computational Linguistics

Statistical studies of languages have focused on the rank-frequency distribution of words. Instead, we introduce here a measure of how word ranks change in time and call this distribution rank diversity. We calculate this diversity for books published in six European languages since 1800, and find that it follows a universal lognormal distribution. Based on the mean and standard deviation associated with the lognormal distribution, we define three different word regimes of languages: “heads” consist of words which almost do not change their rank in time, “bodies” are words of general use, while “tails” are comprised by context-specific words and vary their rank considerably in time. The heads and bodies reflect the size of language cores identified by linguists for basic communication. We propose a Gaussian random walk model which reproduces the rank variation of words in time and thus the diversity. Rank diversity of words can be understood as the result of random variations in rank, where the size of the variation depends on the rank itself. We find that the core size is similar for all languages studied.     

CKD-EPI and Cockcroft-Gault Equations Identify Similar Candidates for Neoadjuvant Chemotherapy in Muscle-Invasive Bladder Cancer

Clinical guidelines suggest neoadjuvant cisplatin-based chemotherapy prior to cystectomy in the setting of muscle-invasive bladder cancer (MIBC). A creatinine clearance (CrCl) >60 mL/min is frequently used to characterize cisplatin-eligible patients, and use of the CKD-EPI equation to estimate CrCl has been advocated. From a prospectively maintained institutional database, patients with MIBC who received cystectomy were identified and clinicopathologic information was ascertained. CrCl prior to surgery was computed using three equations: (1) Cockcroft-Gault (CG), (2) CKD-EPI, and (3) MDRD. The primary objective was to determine if the CG and CKD-EPI equations identified a different proportion of patients who were cisplatin-eligible, based on an estimated CrCl of >60 mL/min. Cisplatin-eligibility was also assessed in subsets based on age, CCI score and race. Actuarial rates of neoadjuvant cisplatin-based chemotherapy use were also reported. Of 126 patients, 70% and 71% of patients were found to be cisplatin-eligible by the CKD-EPI and CG equations, respectively (P = 0.9). The MDRD did not result in significantly different characterization of cisplatin-eligibility as compared to the CKD-EPI and CG equations. In the subset of patients age >80, the CKD-EPI equation identified a much smaller proportion of cisplatin-eligible patients (25%) as compared to the CG equation (50%) or the MDRD equation (63%). Only 34 patients (27%) received neoadjuvant cisplatin-based chemotherapy. Of the 92 patients who did not receive neoadjuvant chemotherapy, 64% had a CrCl >60 mL/min by CG. In contrast to previous reports, the CKD-EPI equation does not appear to characterize a broader span of patients as cisplatin-eligible. Older patients (age >80) may less frequently be characterized as cisplatin-eligible by CKD-EPI. The discordance between actual rates of neoadjuvant chemotherapy use and rates of cisplatin eligibility suggest that other factors (e.g., patient and physician preference) may guide clinical decision-making.