Molecular Biology of Channel Proteins in the Central Nervous System

Heinrich Betz 한국유전학회 1990 Genes & Genomics Vol.12 No.4

Electrical signalling and synaptic transmission in the central nervous system are mediated by the transient activation of different classes of channel proteins which allow for signal propagation along and between excitable cells. Voltage-dependent ion channels control the membrane potential and release of neurotransmitter from presynaptic nerve ending. Ligand-gated ion channels serve as receptors for specific neurotransmitters at peripheral and central synapses. Molecular biology approaches have diclosed primary structures of inhibitory and excitatory neurotransmitter receptor proteins and shown that these belong into a superfamily of evolutionarily related gene products of similar transmembrane topology and quaternary structure. Our laboratory has focused on the investigation of excitatory acetylcholine receptor, glutamate receptor and inhibitory glycine receptor proteins. Structural principles thought to be important for ion conduction through these channels will be discussed. Furthermore, channel proteins have recently have also been disclosed in intracellular membranes including synaptic vesicles. We have analyzed the primary structures of two putative synaptic vesicle channel proteins, synaptophysin and synaptoporin, and discuss the potential role of these channels in the transmitter release process.

Information in the Western Way of Warfare: Too Much of a Good Thing?

( David J. Betz ),( Sang Ho Lee ) 인하대학교 국제관계연구소 2006 Pacific Focus Vol.21 No.23

The proponents of Information War (IW) have mesmerized the public during recent years on the effectiveness and utility of this new style of warfare that ``system of systems``, the network of sensors, communication and precision weapons, will bring power to achieve dominant battlespace knowledge, near-perfect mission assignment, and immediate battlespace assessment which will lift the fog of war and bring victory home. However, the War in Iraq since April 2003 has delivered a sobering and salutary reminder that this is a seductive illusion. The actual practice of IW is tricky to pull off at the operational-tactical level; there have been some real achievements nonetheless. On the Strategic level, however, the results are bad. Judging from the state of the current War on Terror, the insurgents are as adept as the West in waging IW, as they methodically employ unconventional ``asymmetric`` tactics, manipulate media and make their opponent bleed. It is not only the West which can wage information campaigns; in fact it is not at all certain that the West is actually much good at this aspect of warfare in the strategic arena that really counts. While IW offers great advantages in information-driven battlefield, there should be a realization the actual victory cannot be achieved with information alone especially on the strategic level. This is the dilemma which West has to address, in particular, in future struggles against unconventional opponents.

Using a Cascaded H-Bridge STATCOM for Rebalancing Unbalanced Voltages

R.E. Betz,T.J. Summers 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper considers specific issues related to using the cascade (also known as the H-bridge) multilevel STATCOM with unbalanced voltages and currents at the STATCOM-AC line connection terminals. Under this condition the average power into the individual phase legs of the converter, in general, is not zero, although the total three phase power is zero. The resultant phase cluster power unbalance can result in increasing or decreasing capacitor voltages within a phase leg. This paper will present a technique for zeroing the phase cluster average power under unbalanced line conditions when the control strategy is to rebalance unbalanced voltages.

Could a Conservative Challenge Derail China's Reform Programme?

MUSHKAT, Miron,BETZ, Annabel THE INSTITUTE OF EAST AND WEST STUDIES YONSEI UNIV 1992 Global economic review Vol.21 No.2

Continuous Control of Autonomous Vehicles using Plan-assisted Deep Reinforcement Learning

Tanay Dwivedi,Tobias Betz,Florian Sauerbeck,PV Manivannan,Markus Lienkamp 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

End-to-end deep reinforcement learning (DRL) is emerging as a promising paradigm for autonomous driving. Although DRL provides an elegant framework to accomplish final goals without extensive manual engineering, capturing plans and behavior using deep neural networks is still an unsolved issue. End-to-end architectures, as a result, are currently limited to simple driving scenarios, often performing sub-optimally when rare, unique conditions are encountered. We propose a novel plan-assisted deep reinforcement learning framework that, along with the typical state-space, leverages a “trajectory-space” to learn optimal control. While the trajectory-space, generated by an external planner, intrinsically captures the agent’s high-level plans, world models are used to understand the dynamics of the environment for learning behavior in latent space. An actor-critic network, trained in imagination, uses these latent features to predict policy and state-value function. Based primarily on DreamerV2 and Racing Dreamer, the proposed model is first trained in a simulator and eventually tested on the F1TENTH race car. We evaluate our model for best lap times against parametertuned and learning-based controllers on unseen race tracks and demonstrate that it generalizes to complex scenarios where other approaches perform sub-optimally. Furthermore, we show the model’s enhanced stability as a trajectory tracker and establish the improvement in interpretability achieved by the proposed framework.

Surface modification of bulk n-InAs (111)A etched in bromineemethanol

N. Eassa,R. Betz,E. Coetsee,H.C. Swart,A. Venter,J. R. Botha 한국물리학회 2013 Current Applied Physics Vol.13 No.2

X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Raman and photoluminescence spectroscopy were used to evaluate the surface properties of n-type InAs (111)A etched in a 1% Bremethanol solution. Etching completely removes the native oxides from the surface and enhances the photoluminescence response. The adsorption of bromine onto the InAs surface leads to the formation of IneBrx and AseBrx bonds (x ¼ 1, 2, 3) as inferred from changes in the In 3d3/2;5/2 and As 3d core level binding energies. The etch rate is found to decrease due to strong anisotropic effects and the high volatility of the bromine species. A 1 min Bremethanol etch was found to enhance the photoluminescence intensity by a factor of 3, probably due to a reduction in the surface state density upon deoxidation of the surface. This is thought to be due to reductions in the surface state density. The presence of native oxides enhances both the surface accumulation layer and the surface state density.

Optimization of Drug Release from Compressed Multi Unit Particle System (MUPS) Using Generalized Regression Neural Network (GRNN)

Branka Ivic,Svetlana Ibric,Gabriele Betz,Zorica Djuric 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.1

The purpose of this study was development of diclofenac sodium extended release compressed matrix pellets and optimization using Generalized Regression Neural Network (GRNN). According to Central Composite Design (CCD), ten formulations of diclofenac sodium matrix tablets were prepared. Extended release of diclofenac sodium was acomplished using Carbopol ® 71G as matrix substance. The process of direct pelletisation and subsequently compression of the pellets into MUPS tablets was applied in order to investigate a different approach in formulation of matrix systems and to achieve more control of the process factors over the principal response - the release of the drug. The investigated factors were X1 -the percentage of polymer Carbopol® 71 G and X2- crushing strength of the MUPS tablet. In vitro dissolution time profiles at 5 different sampling times were chosen as responses. Results of drug release studies indicate that drug release rates vary between different formulations, with a range of 1 hour to 8 hours of dissolution. The most important impact on the drug release has factor X1-the percentage of polymer Carbopol® 71 G. The purpose of the applied GRNN was to model the effects of these two causal factors on the in vitro release profile of the diclofenac sodium from compressed matrix pellets. The aim of the study was to optimize drug release in manner wich enables following in vitro release of diclofenac sodium during 8 hours in phosphate buffer: 1 h: 15-40%, 2 h: 25-60%, 4 h: 35-75%, 8 h: >70%.

Structural and Functional Analysis of a β₂-Adrenergic Receptor Complex with GRK5

Komolov, Konstantin E.,Du, Yang,Duc, Nguyen Minh,Betz, Robin M.,Rodrigues, Joã,o P.G.L.M.,Leib, Ryan D.,Patra, Dhabaleswar,Skiniotis, Georgios,Adams, Christopher M.,Dror, Ron O.,Chung, Ka Young Cell Press 2017 Cell Vol. No.

<P><B>Summary</B></P> <P>The phosphorylation of agonist-occupied G-protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) functions to turn off G-protein signaling and turn on arrestin-mediated signaling. While a structural understanding of GPCR/G-protein and GPCR/arrestin complexes has emerged in recent years, the molecular architecture of a GPCR/GRK complex remains poorly defined. We used a comprehensive integrated approach of cross-linking, hydrogen-deuterium exchange mass spectrometry (MS), electron microscopy, mutagenesis, molecular dynamics simulations, and computational docking to analyze GRK5 interaction with the β<SUB>2</SUB>-adrenergic receptor (β<SUB>2</SUB>AR). These studies revealed a dynamic mechanism of complex formation that involves large conformational changes in the GRK5 RH/catalytic domain interface upon receptor binding. These changes facilitate contacts between intracellular loops 2 and 3 and the C terminus of the β<SUB>2</SUB>AR with the GRK5 RH bundle subdomain, membrane-binding surface, and kinase catalytic cleft, respectively. These studies significantly contribute to our understanding of the mechanism by which GRKs regulate the function of activated GPCRs.</P> <P><B>PaperClip</B></P> <P>Display Omitted</P> <P><B>Highlights</B></P> <P> <UL> <LI> GRK5-β<SUB>2</SUB>AR binding is enhanced by receptor and kinase ligands and acidic lipids </LI> <LI> GRK5 binding to the β<SUB>2</SUB>AR involves a multi-site interaction </LI> <LI> Receptor binding triggers substantial conformational changes in GRK5 </LI> <LI> RH/catalytic domain separation in GRK5 is essential for receptor phosphorylation </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of Ginsenosides on Glycine Receptor a1 Channels Expressed in Xenopus Oocytes

Seung-Yeol Nah,Jin-Hyeong Noh,Seok Choi,Jun-Ho Lee,Heinrich Betz,Jae-il Kim,Chul-Seung Park,Sang-Mok Lee 한국분자세포생물학회 2003 Molecules and cells Vol.15 No.1