Characterization of ionotropic glutamate receptor-mediated nitric oxide production in vivo in rats

BACKGROUND AND PURPOSE: Glutamate receptor activation can stimulate nitric oxide (NO) production and possibly play a role in long-term potentiation and excitotoxic-mediated injury. We studied the differential effect of agonist-induced activation of ion channel-linked N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subtypes on NO production in vivo in rat hippocampus. We also studied whether dantrolene, a ryanodine calcium channel inhibitor previously shown to attenuate metabotropic glutamate receptor stimulation of NO production, also attenuated ionotropic glutamate receptor-mediated stimulation of NO production. METHODS: Microdialysis probes were placed bilaterally into the CA3 region of the hippocampus of pentobarbital-anesthetized adult Sprague-Dawley rats and were perfused for 5 hours with artificial cerebrospinal fluid (CSF) containing 3 mumol/L [14C]L-arginine. Recovery of [14C]L-citrulline in the effluent was used as a marker of NO production. In 13 groups of rats, increases in [14C]L-citrulline recovery were compared between right- and left-sided probes perfused with no additional drugs versus combinations of NMDA, AMPA, the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME), the non-competitive glutamate receptor blocker MK-801, the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and dantrolene. RESULTS: Recovery of [14C]L-citrulline during perfusion with artificial CSF progressively increased to 272 +/- 73 fmol/min (+/-SEM) over 5 hours. Contralateral perfusion with 1 mmol/L L-NAME inhibited [14C]L-citrulline recovery. Perfusion with 1 mmol/L MK-801 or 1 mmol/L CNQX reduced [14C]L-citrulline recovery compared with contralateral perfusion with CSF alone. Perfusion with 1 mmol/L NMDA enhanced [14C]L-citrulline recovery, and this enhancement was attenuated by L-NAME, MK-801, and CNQX but not by dantrolene. Perfusion with 1 mmol/L AMPA enhanced [14C]L-citrulline recovery, and this enhancement was also attenuated by L-NAME, MK-801, and CNQX but not by dantrolene. CONCLUSIONS: Through an indirect method of assessing NO production in vivo, results with MK-801 and CNQX indicate that NMDA and AMPA receptor activation contribute to basal NO production in the rat hippocampus. Enhanced NO production with NMDA and AMPA agonists appears to involve a complex neuronal interaction because the effect of NMDA was attenuated by both MK-801 and CNQX and because the effect of AMPA was attenuated by both CNQX and MK-801. In contrast to metabotropic glutamate receptor activation, release of calcium from intracellular ryanodine calcium channels does not appear to be a prominent mediator of ionotropic glutamate receptor stimulation of NO production.     

Localization of platelet-derived growth factor beta receptor expression in the periepithelial stroma of human breast carcinoma

The ability of water-insoluble molecules such as triacylglycerols to partition from oil phases into phospholipid interfaces may be crucial to their hydrolysis by lipases in the aqueous environment of plasma and cells. This study uses high resolution and magic angle spinning 13C NMR spectros-copy to measure the solubility of the 8-carbon medium chain triacylglycerol, trioctanoin, in the lamellar structure of phospholipids (vesicles and multilayers) in the presence of other neutral lipids that may compete for an interfacial location (long chain triacylglycerol, cholesteryl ester, and cholesterol). In the presence of a saturating concentration of triolein (approximately 3 mole%), the solubility of trioctanoin in egg phosphatidylcholine vesicles decreased from 10 mole% to 7 mole%. The presence of a saturating concentration of trioctanoin (approximately 10 mole%) decreased the interfacial solubility of long chain triolein to approximately 1 mole%. Cholesteryl oleate in phospholipid vesicles slightly diminished the incorporation of trioctanoin into the surface. The presence of cholesterol reduced the interfacial solubility of trioctanoin, but at a high level of cholesterol (30 mole%), trioctanoin had a solubility of 3 mole%. Thus, even in the presence of other competing neutral lipids, medium chain triacylglycerol retains a favorable location and surface concentration for efficient hydrolysis. 13C NMR analysis thus provides an explanation for preferential hydrolysis of medium, compared to long chain triacylglycerol, in a physical blend of medium and long chain triacylglycerol in a single emulsion particle, and in general, a valuable approach to determine substrate availability at phospholipid surfaces.     

Classification of electroencephalogram signal for the detection of epilepsy using Innovative Genetic Programming

Epilepsy, sometimes called seizure disorder, is a neurological condition that justifies itself as a susceptibility to seizures. A seizure is a sudden burst of rhythmic discharges of electrical activity in the brain that causes an alteration in behaviour, sensation, or consciousness. It is essential to have a method for automatic detection of seizures, as these seizures are arbitrary and unpredictable. A profound study of the electroencephalogram (EEG) recordings is required for the accurate detection of these epileptic seizures. In this study, an Innovative Genetic Programming framework is proposed for classification of EEG signals into seizure and nonseizure. An empirical mode decomposition technique is used for the feature extraction followed by genetic programming for the classification. Moreover, a method for intron deletion, hybrid crossover, and mutation operation is proposed, which are responsible for the increase in classification accuracy and a decrease in time complexity. This suggests that the Innovative Genetic Programming classifier has a potential for accurately predicting the seizures in an EEG signal and hints on the possibility of building a real‐time seizure detection system.     

Robust PCA-based solution to image composition using augmented Lagrange multiplier (ALM)

Computational photography relies on specialized image-processing techniques to combine multiple images captured by a camera to generate a desired image of the scene. We first consider the high dynamic range (HDR) imaging problem. We can change either the exposure time or the aperture while capturing multiple images of the scene to generate an HDR image. This paper addresses the HDR imaging problem for static and dynamic scenes captured using a stationary camera under various aperture and exposure settings, when we do not have any knowledge of the camera settings. We have proposed a novel framework based on sparse representation which enables us to process images while getting rid of artifacts due to moving objects and defocus blur. We show that the proposed approach is able to produce significantly good results through dynamic object rejection and deblurring capabilities. We compare the results with other competitive approaches and discuss the relative advantages of the proposed approach.     

Pattern‐Similarity‐Based Model for Time Series Prediction

This research proposes a pattern/shape‐similarity‐based clustering approach for time series prediction. This article uses single hidden Markov model (HMM) for clustering and combines it with soft computing techniques (fuzzy inference system/artificial neural network) for the prediction of time series. Instead of using distance function as an index of similarity, here shape/pattern of the sequence is used as the similarity index for clustering, which overcomes few of the shortcomings associated with distance‐based clustering approaches. Underlying hidden properties of time series are captured with the help of HMM. The prediction method used here exploits the pattern identification prowess of the HMM for cluster selection and the generalization and nonlinear modeling capabilities of soft computing methods to predict the output of the system. To see the validity of the proposed method in the real‐life scenario, it is tested on four different time series. The first is a benchmark Mackey–Glass time series, which is tested for delay parameters τ = 17 and τ = 30. The remaining time series are monthly sunspot data time series, Laser data time series and the last is Lorenz attractor time series. Simulation results show that the proposed method provide a better prediction performance in comparison with the existing methods.     

Optimization of grooved klystron collector design for efficient heat transfer

Klystron microwave amplifiers play a vital role in addressing the increasing demands of high‐average microwave power for strategic applications such as linear accelerators, active denial technologies, radar, and so forth. Typically, klystrons have an efficiency of 50%‐60% that demands an efficient thermal design for dissipating the unused DC power in the form of spent electron beam in collector. Hence, thermal modeling of the collector for efficient heat dissipation is highly critical in design of high average power klystrons. Of several types of design, grooved collector design is widely employed so as to increase the surface area between the collector and coolant and thereby enhance heat transfer. In this article, a mathematical model and design strategy have been demonstrated to obtain the optimum dimensions, that is, height, depth, and width of fins based on film coefficient and Reynolds number. For validation, the dimensions are then simulated in a computational fluid dynamics software (ANSYS‐Fluent) demonstrating excellent agreement with the mathematical modeling. In addition, the optimum choice of grooving method (longitudinal or crossed) for the given power level has also been provided. The demonstrated strategy can also potentially be employed to other devices, which uses groove based design with water as coolant medium such as gyrotrons, plasma devices, and so forth.     

Effect of bed characteristics on local liquid spreading in a trickle bed

Trickle bed reactors are important to several chemical process applications. While the available computational fluid dynamics models can predict overall liquid volume fraction, the prediction of spatial liquid distribution continues to be a challenging task. In the present work, Eulerian multifluid simulations were performed to investigate the effects of particle size, gas and liquid flow rates, and bed structure on local liquid spreading, and the predictions were validated using measured liquid spreading. It was found that the capillary pressure force caused liquid to spread in the lateral direction and that the interphase interaction forces pushed it in the downward direction and the relative magnitudes of these forces governed the local liquid distribution. While the use of existing capillary pressure force model led to satisfactory prediction of the observed trends of dynamic and steady state local liquid spreading, the modified capillary pressure force led to quantitatively correct predictions of local liquid spreading. © 2016 American Institute of Chemical Engineers AIChE J, 63: 347–357, 2017     

Influence of electron beam radiation on mechanical and thermal properties of styrene‐butadiene‐styrene block copolymer

Electron beam crosslinking of elastomers is a special type of crosslinking technique that has gained importance over conventional chemical crosslinking method, because the former process is fast, pollution free, and simple. The technique involves the impingement of high‐energy electrons generated from electron accelerators and the subsequent production of free radicals on target elastomers. These radicals result in crosslinking of elastomers via radical–radical coupling. In the process, some chain scission may also take place. In this work, a high‐vinyl (～ 50%) styrene‐butadiene‐styrene (S‐B‐S) block copolymer was used as the base polymer. An attempt was made to see the effect of electron beam radiation on the mechanical and thermal properties of the block copolymer. Radiation doses were varied from 25 to 300 kGy. Mechanical properties like tensile strength, elongation at break, modulus at different elongations, hardness, tear strength, crosslink density, and crosslink to chain scission of the irradiated samples were studied and compared with those of unirradiated ones. In this S‐B‐S block copolymer, a relatively low‐radiation dose was found effective in improving the level of mechanical properties. Differential scanning calorimeter and dynamic mechanical analyzer were used to study the thermal characteristics of the irradiated polymer. Influence of a stabilizer at different concentrations on the properties of S‐B‐S at varied radiation doses were also focused on. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010