Multi-screen System Research Articles

Visualización de datos de movilidad en la Ciudad de México, Santa Fe

Las ciudades inteligentes emergen como una estrategia para poder combatir la rápidaurbanización, el incremento acelerado de la población y el congestionamiento vial. Este articulopropone una solución basada en la recolección de datos abiertos, que nos permita encontrarvariables o patrones de comportamiento, para luego ser analizados en un sistema multi-pantalla.A través de este sistema, se pueden generar distintos escenarios con datos reales como: elclima, eventos en la ciudad, fechas de pago; permitiendo a los tomadores de decisiones realizaranalisis criticos de la situación expuesta.

Role of the Transmembrane Domain 4/Extracellular Loop 2 Junction of the Human Gonadotropin-releasing Hormone Receptor in Ligand Binding and Receptor Conformational Selection

Recent crystal structures of G protein-coupled receptors (GPCRs) show the remarkable structural diversity of extracellular loop 2 (ECL2), implying its potential role in ligand binding and ligand-induced receptor conformational selectivity. Here we have applied molecular modeling and mutagenesis studies to the TM4/ECL2 junction (residues Pro(174(4.59))-Met(180(4.66))) of the human gonadotropin-releasing hormone (GnRH) receptor, which uniquely has one functional type of receptor but two endogenous ligands in humans. We suggest that the above residues assume an α-helical extension of TM4 in which the side chains of Gln(174(4.60)) and Phe(178(4.64)) face toward the central ligand binding pocket to make H-bond and aromatic contacts with pGlu(1) and Trp(3) of both GnRH I and GnRH II, respectively. The interaction between the side chains of Phe(178(4.64)) of the receptor and Trp(3) of the GnRHs was supported by reciprocal mutations of the interacting residues. Interestingly, alanine mutations of Leu(175(4.61)), Ile(177(4.63)), and Met(180(4.66)) decreased mutant receptor affinity for GnRH I but, in contrast, increased affinity for GnRH II. This suggests that these residues make intramolecular or intermolecular contacts with residues of transmembrane (TM) domain 3, TM5, or the phospholipid bilayer, which couple the ligand structure to specific receptor conformational switches. The marked decrease in signaling efficacy of I177A and F178A also indicates that IIe(177(4.63)) and Phe(178(4.64)) are important in stabilizing receptor-active conformations. These findings suggest that the TM4/ECL2 junction is crucial for peptide ligand binding and, consequently, for ligand-induced receptor conformational selection.

A Study on Link Set Method in Multi-Screen System

A Study on Link Set Method in Multi-Screen System

Development Assay for of a 5-Hydroxytryptamine2A Receptor Binding High Throughput Screening Using 96-Well Microfilter Plates

A high throughput screening method for the analysis of 5-hydroxytryptamine2A (5-HT2A) receptor binding parameters has been developed, using 96-well filter plates of the Millipore MultiScreen system in combination with a MicroBeta PLUS microplate scintillation counter. MAFB filter plates (GF/B filter over a Durapore membrane) were used because of the lower nonspecific binding of the radioligand to GF/B filter material than to GF/C filters. Comparing different scintillation cocktails, highest counting efficiency and shortest equilibration time were detected with Betaplatescint, after drying the plates at 50°C for 2 h. Measuring the plates without the plastic underdrain increased the counting efficiency by about 39% as compared with counting the plate with the underdrain intact. Presoaking the wells with 0.5% polyethyleneimine for 2 h reduced the nonspecific binding to the filter material by about 50%. A linear relationship of protein concentration and radioligand binding was established up to a protein concentration of 165 μg of protein/well. In the assays, 70 μg of protein/well was generally used, which has turned out to be favorable with respect to the number of counts obtained. When a higher concentration of protein was used, the period of time needed to aspirate the plate was too long because of obstruction of the filter material. Receptor-radioligand equilibration was reached after about 20 min at concentrations less than 0.05 nM [3H]ketanserin-HCl; at higher concentrations it was reached after about 10 min. Saturation analysis of [3H]ketanserin-HCI resulted in a mean Bmax of 393 fmol/mg protein and a KD of 2.0 nM using rat frontal cortex as a receptor source. Competition experiments with known 5-HT2A receptor ligands—DOB-HCl (Ki = 59 nM), DOET-HCl (Ki = 137 nM), DOM-HCl (Ki = 533 nM), DMT (Ki = 1,985 nM), and TMA-HCl (Ki = 22,340 nM)—were in accordance with literature values.

A rapid microtechnique for the estimation of muscarinic and nicotinic receptor binding parameters using 96-well filtration plates

A microtechnique for the assay of muscarinic and nicotinic receptor binding parameters employing a 96-well filtration multiscreen system has been developed. Utilizing rat cerebral cortex as the receptor source, saturation analysis of [ 3H]NMS binding revealed a mean B max and K d value of 1.95 pmol/mg protein and 0.71 nM, respectively. In competition studies with atropine a K i value of 1.67 nM was determined. Nicotinic receptor binding studies were also performed with this technique with [ 3H]Cytisine. The binding constants for both ligands correlated well with established literature values; however, in the nicotinic assays concentrations of ligand at 20 times the K d were required to develop adequate number of counts. Compared to presently available receptor binding techniques, this newly developed system for muscarinic and nicotinic binding is very simple and convenient to use and offers the advantages of speed, accuracy and reproducibility. In addition, a large number of samples can be assayed. This report also presents the first use of the 96-well filtration multiscreen system for the estimation of muscarinic and nicotinic receptor binding constants. This methodology should prove to be useful for determining the binding characteristics of potential cholinergic ligands.

A rapid, high capacity assay for basic fibroblast growth factor binding

A rapid, high capacity assay for the binding of basic fibroblast growth factor has been developed. Rat lung tissue was selected as the optimum source of membranes and 2M sodium chloride used to remove endogenous growth factor. The assay has been adapted to the Miltipore Multi-Screen system so that it can be run in 96-well format with a volume of 300 μl. The assay has been validated through the demonstration of inhibition by standard inhibitors such as suramin and protamine sulfate. The assay has proven useful for the screening of random compounds as well as the more detailed examination of suspected inhibitors. By running compounds in the presence and absence of a mid-range concentration of unlabeled bFGF, an estimate of the proportion of the inhibition due to high affinity binding can be obtained. Suramin and protamine sulfate show no selectivity and inhibit high affinity binding and overall binding with similar potencies. Another inhibitor, dimercaptothiadiazole, is more potent against high affinity binding.

Studies on topical chemotherapy of tumor-contaminated surgical wounds

Chemotherapeutic compounds for irrigation of potentially tumor-contaminated surgical fields were evaluated in a multiscreen system. Sixty compounds were tested for their ability to produce total tumor inhibition when mixed with Ehrlich-Lettre ascites tumor in vitro prior to intraperitoneal injection in mice. Compounds which passed this screen without causing any systemic toxic effects were tested in rabbit wounds contaminated with V-2 carcinoma. They were also tested for their ability to inhibit dehydrogenases in fresh normal and malignant tissue from individual patients. The most effective compounds were used for irrigation of surgical wounds following excision of extensive cancer of the upper parts of the gastrointestinal and respiratory tracts. Surgical wounds of fifty-six patients were irrigated, thirty-nine with test compounds and seventeen with saline solution as a control. The incidence of tumor recurrence in wounds irrigated with the compounds was compared with that in wounds irrigated with saline solution. Data available, thus far, show that the recurrence rate was higher in wounds irrigated with nitrogen mustard and sodium hypochlorite than in wounds irrigated with saline solution.

Analytical solutions for rotary matrix wire screen heat exchangers

Instead of the partial differential equation commonly used for rotary matrix heat exchangers, an ordinary differential equation is developed for a single stage rotary wire screen heat exchanger. This equation results in an exact solution for tem perature effectiveness. The solution for a multi-screen system is then developed by an energy balance of each individual single screen. Based on analytical solutions obtained here, design charts for rotary multilayer wire screen heat exchangers are presented.