Role of ionotropic GABA,glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

Background  

Cardiac vagal preganglionic neurons (CVPN) are responsible for the tonic, reflex and respiratory modulation of heart rate (HR). Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR) alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT_1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve.     

Chemical Composition,Antioxidant, Antibacterial,and Antibiofilm Activities of Backhousia citriodora Essential Oil

The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography–mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC₅₀ of 42.57 μg/mL and EC₅₀ of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors’ knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.     

Phase transitions in ultraoriented polyethylene fibers under moderate pressures: A synchrotron X-ray study

The effect of pressure on phase transformations of ultradrawn ultra-high-molecular-weight polyethylene (UHMWPE) fibers was examined by in situ X-ray diffraction measurements with synchrotron radiation. The mesomorphic hexagonal phase was metastable even at a relatively low pressure of about 100 bar. The effect of pressure on the melting transitions was larger than in chain-folded structures. The existence and metastability of the hexagonal phase is the basis of compaction technology of UHMWPE fibers in composite materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 53–59, 2004     

Biodegradable Polymers from Renewable Sources. New Hemicellulose‐Based Hydrogels

Hemicellulose/poly(2‐hydroxyethyl methacrylate) (PHEMA)‐based hydrogels were prepared by the radical polymerization of HEMA with hemicellulose purposely modified with well‐defined amounts of methacrylic functions using a redox initiator system. Oligomeric hydrosoluble hemicelluloses produced from spruce chips were used for modification studies. The chemical modification of hemicellulose was performed with 2‐[(1‐imidazolyl)formyloxy]ethyl methacrylate as a modifying agent and triethylamine as the catalyst. The kinetics of the modification reaction was monitored by means of ¹H NMR spectroscopy. The resulting hydrogels obtained after a 30 min reaction were homogeneous, elastic, and transparent materials.     

Main‐chain functionalization of poly(L‐lactide) with pendant unsaturations

Main‐chain‐functionalized poly(L ‐lactide) (PLLA) with pendant unsaturations was synthesized through a one‐pot postpolymerization procedure with the PLLA homopolymer as the starting material. The material was functionalized through α‐hydrogen abstraction by a sterically hindered strong base, lithium diisopropylamide, followed by the addition of an acid chloride. Two different acid chlorides were examined, lauroyl chloride as a concept electrophile and oleoyl chloride to provide the pendant unsaturations. The semisolvated system, together with branching reactions from the alpha position of the acid chloride, yielded a high molar amount of the incorporated reactant in the material. The unsaturations were preserved under the chosen conditions and the material exhibited surfactant‐like properties in blends with oleic acid and PLLA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthetic pathways enables the design of functionalized poly(lactic acid) with pendant mercapto groups

Functionalized poly(lactic acid) having sulfur‐protected groups along the chain have been synthesized with the ultimate aim to obtain materials for reversible and degradable self‐assembly systems. The first step in the synthesis was the preparation of hydroxy‐(4‐methyl‐phenylsulfanyl)‐propionic acid and hydroxy‐(tritylsulfanyl)‐propionic acid. These sulfur‐functionalized hydroxy acids were subsequently used as comonomers in the condensation polymerization of lactic acid producing functionalized polyesters with thio‐protected groups along the chain. The ratio of functionalized hydroxyl‐acid in the copolymer was determined by the feed ratio. The polyesters obtained were amorphous and size exclusion chromatography analysis showed a monomodal distribution. When treated with iodine, the polyesters chains bearing the tritylsulfanyl side groups assembled with the formation of S? S bridges and the molecular weight increased accordingly. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Artificial viscosity: back to the basics

In this paper, we take a different perspective on the derivation of artificial viscosity. Heretofore, the development of artificial viscosity has been based on the paper published in Journal of Applied Physics in 1950 authored by John von Neumann and Robert Richtmyer [1]. Earlier, in 1948, Richtmyer published a report at Los Alamos Scientific Laboratory documenting the original concept [2]. This report was the true origin of shock capturing methods and contains several key ideas that are conceptually different than the 1950 journal article. Unfortunately, this report (LA‐671) was classified until 1993. This has resulted in two issues: the misattribution of the invention of artificial viscosity as primarily being the work of von Neumann and the loss of the structurally different ideas in the original report. We seek to right the record of history here and use the ideas contained in Richtmyer's report to good effect in deriving a new shock viscosity. The focus of previous development has been the Hugoniot curve describing the locus of states connected by a single shock wave. Here we follow a path more focused upon the Rayleigh line, which is strongly guided by Richtmyer's line of development of the original artificial viscosity formulation. We provide an implementation of the method resulting from this perspective and computational results for simple shock problems. Copyright © 2014 John Wiley & Sons, Ltd.