bluuebunny/crossref_metadata_2025 huggingface dataset:
QUANTUM PHASE TRANSITIONAL BEHAVIOR IN THE EXTENDED CASTEN TRIANGLE OF THE INTERACTING BOSON MODEL
Authors: PAN FENG , WANG TAO , HUO Y.-S. , DRAAYER J. P.
Published: January 2007

Quantum phase transitional patterns in the whole parameter space of the consistent-Q Hamiltonian in the Interacting Boson Model are studied based on an implemented Fortran code for numerical computation of the matrix elements in the SU (3) Draayer-Akiyama basis. Results with respect to both ground and some excited states of the model Hamiltonian are discussed. Quantum phase transitional behavior under a variety of parameter situations is shown. It is found that transitional behavior of excited states is more complicated. Pt isotopes are taken as examples in illustrating the prolate-oblate shape phase transition.
PAIRING INTERACTION POTENTIAL WITH REALISTIC FORCE IN NEUTRON AND NUCLEAR MATTER
Authors: SHEN CAIWAN
Published: January 2007

Using the realistic nucleon-nucleon interaction, we studied the pairing interaction potential for 1S0 and 3S1 channel in neutron and nuclear matter. The explicit formulas are given for the calculation. It is found that the screening using realistic force is much smaller than that using effective interaction, for instance, Gogny force or G-matrix.
BCS-TYPE THEORY IN CANONICAL ENSEMBLES
Authors: NAKADA H. , TANABE K.
Published: January 2007

To investigate the pairing phase transition in finite systems with the particle-number conservation, we formulate a new BCS-type theory at finite temperature, by deriving a set of variational equations of the free energy after the particle-number projection. This theory enables us to distinguish the symmetry-restoring fluctuation (SRF) from additional quantum fluctuations. By numerical calculations, it is found that the phase transition is compatible with the conservation law in this theory, and that the SRF shifts up the critical temperature. Having correct zero-temperature limit, this theory also gives new interpretation on the Pauli blocking effect in systems with odd particle number.
SHELL MODEL FOR HEAVY NUCLEI AND ITS APPLICATION IN NUCLEAR ASTROPHYSICS
Authors: SUN YANG
Published: January 2007

Performing shell model calculations for heavy nuclei is a long-standing problem in nuclear physics. The shell model truncation in the configuration space is an unavoidable step. The Projected Shell Model (PSM) truncates the space under the guidance of the deformed mean-field solutions. This implies that the PSM uses a novel and efficient way to bridge the two conventional methods: the deformed mean-field approximations, which are widely applied to heavy nuclei but able to describe the physics only in the intrinsic frame, and the spherical shell model diagonalization method, which is most fundamental but feasible only for small systems. We discuss the basic philosophy in construction of the PSM (or generally PSM-like) approach. Several examples from the PSM calculations are presented. Astrophysical applications are emphasized.
PROJECTED SD-PAIR SHELL MODEL
Authors: LUO Y. A. , PAN F. , DRAAYER J. P. , NING P. Z.
Published: January 2007

Based on a nucleon-pair shell model, a projected SD-pair shell model is proposed. It is found that within this model, the classical limiting cases in interacting boson model and the experimental spectrum can all be reproduced approximately.
ANGULAR MOMENTUM PROJECTION AFTER VARIATION FOR CRANKING SHELL MODEL
Authors: ZHENG R. R. , ZHU S. Q. , YANG Y. C. , ZENG J. Y. , LIU S. X. , ZHAO E. G.
Published: January 2007

Probabilities of angular momentum I projected states from six particles Cranking Shell Model (CSM) as a function of cranking frequency ω are calculated and its validity is studied carefully. The generalized eigenvalue equations of I projected states are solved. All the results show that the I projected states of the CSM eigenfunctions have totally different properties from the rigid rotor approximated by a phenomenological model.
SYMMETRIES AND STRUCTURE IN THE fp SHELL AND g9/2 SHELL
Authors: ZAMICK LARRY , ESCUDEROS ALBERTO
Published: January 2007

First in a single-j-shell calculation (j = f7/2) we discuss various symmetries, e.g., two to one in 44 Ti vs 43 Ti . We note that the wave function amplitudes for T(higher) states are coefficients of fractional parentage, and that orthogonality of T(higher) and T(lower) states leads to useful results. Then we consider what happens if T = 0 two-body matrix elements are set equal to zero. We find a partial dynamical symmetry with several interesting degeneracies. It is noted that some formulae developed for identical particles also apply to different (companion) problems involving mixed systems of protons and neutrons. In the g9/2 shell, where one can have for the first time seniority violation for identical particles, we find some interesting yet unproven results.
THE HIGH-RESOLUTION IN-FLIGHT SPECTROSCOPY (HISPEC) PROJECT AT FAIR
Authors:   For the HISPEC collaboration., PODOLYÁK ZSOLT
Published: January 2007

The FAIR facility with its high-energy and high-intensity secondary radioactive ion beams will be unique worldwide. The HIgh-resolution in-flight SPECtroscopy (HISPEC) project will use these rare beams at energies of E/A = 3–150 MeV for studies in nuclear structure, reactions and astrophysics. A brief review of the physics questions addressed and the proposed experimental setup are presented.
NUCLEAR MATTER PROPERTIES FROM COLLECTIVE MODES IN NUCLEI
Authors: SHLOMO SHALOM , AU V. KIM
Published: January 2007

Bulk properties of nuclear matter associated with the equation of state, the nuclear matter incompressibility coefficient, Knm, in particular, are very important physical quantities required in the study of properties of nuclei, supernova collapse, neutron stars and heavy-ion collisions. Here we review the current status of Knm and the experimental and theoretical methods used to determine the value of Knm from the excitation cross-sections and the transition strength distributions of compression modes in nuclei, mainly the the isoscalar giant monopole resonance and the isoscalar giant dipole resonance.
DECAY SPECTROSCOPY (DESPEC) AT THE NEW FAIR-NUSTAR FACILITY
Authors:   For the DESPEC collaboration., RUBIO BERTA
Published: January 2007

This contribution describes DESPEC (DEcay SPECtroscopy) which together with HISPEC (see the corresponding contribution to this conference) constitutes one of the proposed and accepted joint experiments of NuSTAR (Nuclear STucture, Astrophysics and Reactions), the part of the new FAIR facility that focuses on the production and study of beams of radioactive nuclei created by the fragmentation method.
INDIRECT MEASUREMENTS OF NUCLEAR ASTROPHYSICS REACTIONS USING UNSTABLE NUCLEAR BEAMS
Authors: LIU WEI-PING , LI ZHI-HONG , BAI XI-XIANG , WANG YOU-BAO , LIAN GANG , GUO BING , ZENG SHENG , YAN SHENG-QUAN , WANG BAO-XIANG , SU JUN , SHU NENG-CHUAN , CHEN YONG-SHOU
Published: January 2007

This paper described the nuclear astrophysical studies using the unstable ion beam facility GIRAFFE, by indirect measurements. We measured the angular distributions for some single proton or neutron transfer reactions, such as 7 Be ( d,n )8 B , 11 C ( d,n )12 N , 8 Li ( d,n )9 Be , 8 Li ( d,p )9 Li and 13 N ( d,n )14 O in inverse kinematics, and derived the astrophysical S-factors or reaction rates of 7 Be ( p ,γ)8 B , 11 C ( p ,γ)12 N , 8 Li ( n ,γ)9 Li , 13 N ( p ,γ)14 O by asymptotic normalization coefficient, spectroscopic factor, and R-matrix approach at astrophysically relevant energies.
PRESENT STATUS OF HIRFL IN LANZHOU
Authors: ZHAN WENLONG , XU HUSHAN , SUN ZHIYU , XIAO GUOQING , XIA JIAWEN , ZHAO HONGWEI , SONG MINGTAO , YUAN YOUJIN , HIRFL-CSR GROUP
Published: January 2007

HIRFL has been upgraded for basic research on nuclear physics, atomic physics, irradiative material and biology from beginning of this decade. So far, the main performances of HIRFL have improved in the beam species from light ion to uranium and the maximum beam intensities reaching ~10μA from SFC, 1.5 μA from SSC. Therefore, some experiments have been performed during this period, especially, on new isotope synthesis and unstable nuclear physics. The new upgrading project Cooling Storage Ring (CSR) is under commissioning by ~2p μA carbon beam stripping injection. About 109 C ion have stored inside CSRm, and part of them have been cooling down by the electron cooler. The acceleration of CSRm also has been test successful. Some future experiment are under development.
PERSISTENCE OF ROTATIONAL STRUCTURE IN NUCLEI AND QUASI-DYNAMICAL SYMMETRY
Authors: THIAMOVA G. , ROWE D. J.
Published: January 2007

The existence of quasi-dynamical symmetry (QDS) in physical systems and its significance for understanding the persistence of rotational structure in nuclei is explained in terms of the mathematical concept of an embedded representation. We consider the spectra obtained by coupling two SU (3) irreps by means of a quadrupole-quadrupole interaction. For a particular large value of this interaction, the two irreps combine to form a single (strongly-coupled) irrep while for zero interaction the weakly-coupled results are mixtures of many irreps. A notable result is the persistence of the rotor character of the low-energy states for a wide range of the interaction strength which can be explained by coherent mixing of SU (3) irreps. Such a coherent mixing of representations is an indication that the model has a QDS. Also notable is the fact that, for very weak interaction strengths, the rotational states of the yrast band approach those of a vibrational sequence while the B( E 2) transition strengths remain close to those of an axially symmetric rotor.
NODE DEGREE DISTRIBUTION IN COMPLEX MICROVASCULAR NETWORKS: A POTENTIAL NEW DIAGNOSTIC TOOL FOR EXTRACELLULAR MATRIX-RELATED DISEASES
Authors: DE FELICE CLAUDIO , BARDUCCI ALESSANDRO , LATINI GIUSEPPE , BIANCIARDI GIORGIO , PARRINI STEFANO
Published: January 2007

Recent research indicates the presence of increased vascular density and irregularity on oral mucosal vascular networks in extracellular matrix (ECM)-related illness or conditions. Here, we estimated the frequency of occurrence of nodes of various degrees (K3, K4 and K5, where Kn designates a node with n connections) in patients with proven or suspected ECM-related conditions and in controls. Subjects with ECM-related conditions exhibited lower K3 and higher K4 frequency than controls (p < 0.0001) in their vascular networks. Inverse statistical correlations between the local fractal dimension and L-Z values and percentage of K3 (Pearson's r values range: -0.91 to -0.81; p values range: 0.0013 to < 0.0001), together with a positive relationship with K4 were observed (r values range: 0.81 to 0.86; p values range: 0.0015 to 0.0003). A positive correlation coefficient between D(1–46) and K5 frequency was also found (r = 0.6334, p = 0.027). K3 ≥ 52% or K4 <28% discriminated ECM patients from controls with 100% sensitivity (true positive cases to true positive + false negative ratio) and specificity (true negative cases to true negative + false positive ratio). These findings suggest that node degree distribution in oral vascular networks could be a helpful new marker of pathological conditions associated with proven or suspected ECM abnormalities.
A NOTE ON FRACTALS OF ONE FORBIDDEN WORD AND THEIR BOX DIMENSIONS
Authors: HUANG CHENGXING , PENG SHOU-LI
Published: January 2007

We provide some special algorithms to construct the fractals which have not been constructed previously. Our generalized graphical representation can be applied to any alphabet with any cardinal number. It is noted that the Hao's frame representation and the Tino's generalization are the special cases of our result. Moreover, we will apply the recurrence formula to derive their characteristic equations and roots.
SCALING ATTRACTORS OF FRACTIONAL DIFFERENTIAL SYSTEMS
Authors: LI CHANGPIN , DENG WEIHUA , CHEN GUANRONG
Published: January 2007

In this paper, scaling attractors of fractional differential systems are studied with the help of synchronization methods. The synchronization error systems between the drive and response systems are analyzed by using the theory of Laplace transform. An efficient computational scheme is developed. Both numerical simulations and computer graphics show that the developed techniques work well.
THE GEOMETRIC MEASURE OF ENTANGLEMENT OF THREE-PARTITE PURE STATES
Authors: KAZAKOV A. YA.
Published: January 2007

As a measure of entanglement of three-partite pure state, the distance between this state and a set of fully disentangled states is considered. This distance can be calculated for W-class three-qubit pure states and generalized GHZ-states in explicit analytical form. For general multipartite pure states, the distance up to the set of 1-disentangled states is derived. This value can be considered as a low bound for the entanglement of multipartite pure state.
QUANTUM SECURE DIRECT COMMUNICATION WITHOUT A PRE-ESTABLISHED SECURE QUANTUM CHANNEL
Authors: WANG JIAN , ZHANG QUAN , TANG CHAOJING
Published: January 2007

Most of the quantum secure direct communication protocols need a pre-established secure quantum channel. Only after ensuring the security of quantum channel can the sender encode the secret message and send it to the receiver through the secure channel. In this paper, we present a quantum secure direct communication protocol using Einstein–Podolsky–Rosen pairs and teleportation. It is unnecessary for the present protocol to ensure the security of the quantum channel before transmitting the secret message. In the present protocol, all Einstein–Podolsky–Rosen pairs are used to transmit the secret message except those chosen for eavesdropping check. We also discuss the security of our protocol under several eavesdropping attacks.
NOISE TOLERANCE OF THE BB84 PROTOCOL WITH RANDOM PRIVACY AMPLIFICATION
Authors: WATANABE SHUN , MATSUMOTO RYUTAROH , UYEMATSU TOMOHIKO
Published: January 2007

This paper shows that the random privacy amplification is secure with a higher key rate than Mayers' evaluation at the same error rate in the BB84 protocol with one-way or two-way classical communications. There exists only Mayers' evaluation on the secure key rate with random privacy amplification that is applicable to the BB84 protocol with two-way classical communications. Our result improves the secure key rate of the random privacy amplification in the BB84 protocol with two-way classical communications.
ALTERNATIVE DERIVATION OF THE CRITERION FOR ECONOMICAL REALIZATION OF ONE-TO-TWO QUBIT CLONING
Authors: DURT THOMAS , DU JIANGFENG , DAGHAY SALUA
Published: January 2007

In a previous paper [Phys. Rev. A69 (2004) 062316], two of us (JD and TD) derived a necessary and sufficient condition for the reducibility of 3 qubit one-to-two cloners to 2 qudit one-to-two cloners. When this criterion is fulfilled, economical cloning is possible. We show in the present paper how to generalize the assumptions under which this condition is valid. We also extend this result to qudit one-to-two cloners, with d finite but arbitrary.
QUANTUM COMPUTATION FOR ACTION SELECTION USING REINFORCEMENT LEARNING
Authors: CHEN C. L. , DONG D. Y. , CHEN Z. H.
Published: January 2007

This paper proposes a novel action selection method based on quantum computation and reinforcement learning (RL). Inspired by the advantages of quantum computation, the state/action in a RL system is represented with quantum superposition state. The probability of action eigenvalue is denoted by probability amplitude, which is updated according to rewards. And the action selection is carried out by observing quantum state according to collapse postulate of quantum measurement. The results of simulated experiments show that quantum computation can be effectively used to action selection and decision making through speeding up learning. This method also makes a good tradeoff between exploration and exploitation for RL using probability characteristics of quantum theory.
PHOTON-ASSISTED INTERSUBBAND TRANSITIONS IN A QUANTUM WIRE
Authors: GUDWANI MONICA , PRASAD VINOD , JHA PRADEEP KUMAR , MOHAN MAN
Published: January 2007

We investigate the response of electrons confined in a quantum wire in the presence of intense terahertz (THz) electric field. An exact and powerful nonperturbative fundamental approach of Floquet theory is employed to solve the equation of motion for resonantly driven intersubband transitions. Several interesting features namely dynamic Stark shift, power broadening and hole-burning are observed with the variation in electric field strength. In addition, the degeneracy between several excited states is found to be removed in the presence of high electric field.
MICROSCOPIC CHARACTERIZATION OF THIN-MULTIWALL CARBON NANOTUBES SYNTHESIZED BY CATALYTIC CVD METHOD WITH MESOPOROUS SILICA
Authors: RAMESH PALANISAMY , SATO KENICHI , OZEKI YUJI , YOSHIKAWA MASAHITO , KISHI NAOKI , SUGAI TOSHIKI , SHINOHARA HISANORI
Published: January 2007

Carbon nanotubes with 1–6 walls have been grown on cobalt-loaded mesoporous silica (i.e., MCM41) by using acetylene catalytic chemical vapor deposition. It is found that titanium grafting on the MCM41 pore walls prior to cobalt loading promotes the growth of nanotubes with 1–6 walls. As-grown nanotube material is found to be a mixture of single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs) and thin-multiwall carbon nanotubes (t-MWNTs) with 3–6 walls. Annealing of the as-grown nanotubes has reduced the amount of SWNTs in the nanotube mixture. Several structural deformations of the t-MWNTs are observed during transmission electron microscopy (TEM) analysis. Complete or partial collapse of the t-MWNTs is also found due to these structural deformations. Graphite-like domains developed at the collapsed regions stabilize these structural deformations.
FABRICATION OF GAS SENSOR USING SINGLE-WALLED CARBON NANOTUBES DISPERSED IN DICHLOROETHANE
Authors: JEONG SEUNG YOL , KIM KI KANG , AN KAY HYEOK , HWANG HA RYONG , HAN CHANG SOO , YUN MIN HEE , LEE YOUNG HEE
Published: January 2007

The single-walled carbon nanotube (SWCNT)-field effect transistor (FET) gas sensor was fabricated by spin-coating SWCNTs dispersed in dichloroethane (DCE) solvent on silicon substrate. Raman spectra revealed that walls of the nanotubes were well preserved without much damage during DCE treatment. The sensitivity of the gas sensor was strongly dependent on the series resistance. The sensitivity was maximized in the reasonable contact resistance between nanotubes and electrodes. This was attributed to the suppression of the dark current. The SWCNT gas sensor revealed typical p-type characteristics with respect to NO 2 and NH 3 gases. The small-bundled SWCNTs increased accessibility of gases to nanotubes and therefore increased the sensitivity of the nanotube gas sensor. The response time was shortened particularly in the case of NO 2 gas compared to the previous report.
MAGNETIC FORCE MICROMANIPULATION SYSTEMS FOR THE BIOLOGICAL SCIENCES
Authors: FISHER J. K. , VICCI L. , CRIBB J. , O'BRIEN E. T. , TAYLOR R. M. , SUPERFINE R.
Published: January 2007

Manipulation systems using magnetic field gradients have the ability to apply a large range of forces noninvasively to a specific target. Depending on the requirements of a given experiment, the systems may be as simple as a single electromagnet for unidirectional manipulation or as complex as a high-frequency three-dimensional manipulator with force feedback. Here, we discuss the motivation for developing such systems, theory and design considerations, and give examples of the broad range of manipulators that has been put to use. In addition, we discuss a variety of applications demonstrating the range of experiments for which such a system is applicable.
EFFECT OF REACTION TEMPERATURE ON THE PRODUCTION OF CARBON NANOTUBES
Authors: MUATAZ A. A. , AHMADUN F. , GUAN C. , MAHDI E. , RINALDI A.
Published: January 2007

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high quality and quantity carbon nanotubes. The reaction temperature was optimized to produce high yield and purity of the carbon nanotubes. The reaction temperatures were varied from 500–850°C. The result shows that carbon nanotubes were observed from 600°C to 850°C with maximum numbers and high purity at 850°C. The diameter range of CNTs varied from 2 to 55 nm. The results of the present investigation suggest that the observed changes in catalytic activity and selectivity accompanying an increase in temperature are probably due to major alterations in the distribution of atoms at the metal/gas interface. Thermodynamically, higher temperatures favor the surface decomposition of hydrocarbon rather than the hydrogenation reactions.
Atrophy, but not necrosis, in rabbit skeletal muscle denervated for periods up to one year
Authors: Ashley Z. , Sutherland H. , Lanmüller H. , Russold M. F. , Unger E. , Bijak M. , Mayr W. , Boncompagni S. , Protasi F. , Salmons S. , Jarvis J. C.
Published: January 2007

Our understanding of the effects of long-term denervation on skeletal muscle is heavily influenced by an extensive literature based on the rat. We have studied physiological and morphological changes in an alternative model, the rabbit. In adult rabbits, tibialis anterior muscles were denervated unilaterally by selective section of motor branches of the common peroneal nerve and examined after 10, 36, or 51 wk. Denervation reduced muscle mass and cross-sectional area by 50–60% and tetanic force by 75%, with no apparent reduction in specific force (force per cross-sectional area of muscle fibers). The loss of mass was associated with atrophy of fast fibers and an increase in fibrous and adipose connective tissue; the diameter of slow fibers was preserved. Within fibers, electron microscopy revealed signs of ultrastructural disorganization of sarcomeres and tubular systems. This, rather than the observed transformation of fiber type from IIx to IIa, was probably responsible for the slow contractile speed of the muscles. The muscle groups denervated for 10, 36, or 51 wk showed no significant differences. At no stage was there any evidence of necrosis or regeneration, and the total number of fibers remained constant. These changes are in marked contrast to the necrotic degeneration and progressive decline in mass and force that have previously been found in long-term denervated rat muscles. The rabbit may be a better choice for a model of the effects of denervation in humans, at least up to 1 yr after lesion.
Isoflurane preconditioning uncouples mitochondria and protects against hypoxia-reoxygenation
Authors: Ljubkovic Marko , Mio Yasushi , Marinovic Jasna , Stadnicka Anna , Warltier David C. , Bosnjak Zeljko J. , Bienengraeber Martin
Published: January 2007

Ischemic cardiac injury can be substantially alleviated by exposing the heart to pharmacological agents such as volatile anesthetics before occurrence of ischemia-reperfusion. A hallmark of this preconditioning phenomenon is its memory, when cardioprotective effects persist even after removal of preconditioning stimulus. Since numerous studies pinpoint mitochondria as crucial players in protective pathways of preconditioning, the aim of this study was to investigate the effects of preconditioning agent isoflurane on the mitochondrial bioenergetic phenotype. Endogenous flavoprotein fluorescence, an indicator of mitochondrial redox state, was elevated to 195 ± 16% of baseline upon isoflurane application in intact cardiomyocytes, indicating more oxidized state of mitochondria. Isoflurane treatment also elicited partial dissipation of mitochondrial transmembrane potential, which remained depolarized even after anesthetic withdrawal (tetramethylrhodamine fluorescence intensity declined to 83 ± 3 and 81 ± 7% of baseline during isoflurane exposure and washout, respectively). Mild uncoupling, with preserved ATP synthesis, was also detected in mitochondria that were isolated from animals that had been previously preconditioned by isoflurane in vivo, revealing its memory nature. These mitochondria, after exposure to hypoxia and reoxygenation, exhibited better preserved respiration and ATP synthesis compared with mitochondria from nonpreconditioned animals. Partial mitochondrial depolarization was paralleled by a diminished Ca2+ uptake into isoflurane-treated mitochondria, as indicated by the reduced increment in rhod-2 fluorescence when mitochondria were challenged with increased Ca2+ (180 ± 24 vs. 258 ± 14% for the control). In conclusion, isoflurane preconditioning elicits partial mitochondrial uncoupling and reduces mitochondrial Ca2+ uptake. These effects are likely to reduce the extent of the mitochondrial damage after the hypoxic stress.
β-Defensin overexpression induces progressive muscle degeneration in mice
Authors: Yamaguchi Yasuhiro , Nagase Takahide , Tomita Tetsuji , Nakamura Kyoko , Fukuhara Shigetomo , Amano Tomokazu , Yamamoto Hiroshi , Ide Yukie , Suzuki Misao , Teramoto Shinji , Asano Tomoichiro , Kangawa Kenji , Nakagata Naomi , Ouchi Yasuyoshi , Kurihara Hiroki
Published: January 2007

Defensins comprise a family of cationic antimicrobial peptides characterized by conserved cysteine residues. They are produced in various organs including skeletal muscle and are identified as key elements in the host defense system as potent effectors. At the same time, defensins have potential roles in the regulation of inflammation and, furthermore, can exert cytotoxic effects on several mammalian cells. Here, we developed transgenic mice overexpressing mouse β-defensin-6 to explore the pathophysiological roles of the defensin family as a novel mediator of inflammatory tissue injury. Unexpectedly, the transgenic mice showed short lifespan, poor growth, and progressive myofiber degeneration with functional muscle impairment, predominant centronucleated myofibers, and elevated serum creatine kinase activity, as seen in human muscular dystrophy. Furthermore, some of the transgenic myofibers showed IκBα accumulation, which would be related to the myofiber apoptosis of limb-girdle muscular dystrophy type 2A. The present findings may unravel a concealed linkage between the innate immune system and the pathophysiology of degenerative diseases.
Inhibition of zipper-interacting protein kinase function in smooth muscle by a myosin light chain kinase pseudosubstrate peptide
Authors: Ihara Eikichi , Edwards Elena , Borman Meredith A. , Wilson David P. , Walsh Michael P. , MacDonald Justin A.
Published: January 2007

As a regulator of smooth muscle contractility, zipper-interacting protein kinase (ZIPK) appears to phosphorylate the regulatory myosin light chain (RLC20), directly or indirectly, at Ser19 and Thr18 in a Ca2+-independent manner. The calmodulin-binding and autoinhibitory domain of myosin light chain kinase (MLCK) shares similarity to a sequence found in ZIPK. This similarity in sequence prompted an investigation of the SM1 peptide, which is derived from the autoinhibitory region of MLCK, as a potential inhibitor of ZIPK. In vitro studies showed that SM1 is a competitive inhibitor of a constitutively active 32-kDa form of ZIPK with an apparent Ki value of 3.4 μM. Experiments confirmed that the SM1 peptide is also active against full-length ZIPK. In addition, ZIPK autophosphorylation was reduced by SM1. ZIPK activity is independent of calmodulin; however, calmodulin suppressed the in vitro inhibitory potential of SM1, likely as a result of nonspecific binding of the peptide to calmodulin. Treatment of ileal smooth muscle with exogenous ZIPK was accompanied by an increase in RLC20 diphosphorylation, distinguishing between ZIPK [and integrin-linked kinase (ILK)] and MLCK actions. Administration of SM1 suppressed steady-state muscle tension developed by the addition of exogenous ZIPK to Triton-skinned rat ileal muscle strips with or without calmodulin depletion by trifluoperazine. The decrease in contractile force was associated with decreases in both RLC20 mono- and diphosphorylation. In summary, we present the SM1 peptide as a novel inhibitor of ZIPK. We also conclude that the SM1 peptide, which has no effect on ILK, can be used to distinguish between ZIPK and ILK effects in smooth muscle tissues.
Tin protoporphyrin induces intestinal chloride secretion by inducing light oxidation processes
Authors: Uc Aliye , Reszka Krzysztof J. , Buettner Garry R. , Stokes John B.
Published: January 2007

Heme induces Cl− secretion in intestinal epithelial cells, most likely via carbon monoxide (CO) generation. The major source of endogenous CO comes from the degradation of heme via heme oxygenase (HO). We hypothesized that an inhibitor of HO activity, tin protoporphyrin (SnPP), may inhibit the stimulatory effect of heme on Cl− secretion. To test this hypothesis, we treated an intestinal epithelial cell line (Caco-2 cells) with SnPP. In contrast to our expectations, Caco-2 cells treated with SnPP had an increase in their short-circuit currents ( Isc) in Ussing chambers. This effect was observed only when the system was exposed to ambient light. SnPP-induced Isc was caused by Cl− secretion because it was inhibited in Cl−-free medium, with ouabain or 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB). The Cl− secretion was not via activation of the CFTR, because a specific inhibitor had no effect. Likewise, inhibitors of adenylate cyclase and guanylate cyclase had no effect on the enhanced Isc. SnPP-induced Isc was inhibited by the antioxidant vitamins, α-tocopherol and ascorbic acid. Electron paramagnetic resonance experiments confirmed that oxidative reactions were initiated with light in cells loaded with SnPP. These data suggest that SnPP-induced effects may not be entirely due to the inhibition of HO activity but rather to light-induced oxidative processes. These novel effects of SnPP-photosensitized oxidation may also lead to a new understanding of how intestinal Cl− secretion can be regulated by the redox environment of the cell.
Regulation of Triglyceride Metabolism.IV. Hormonal regulation of lipolysis in adipose tissue
Authors: Jaworski Kathy , Sarkadi-Nagy Eszter , Duncan Robin E. , Ahmadian Maryam , Sul Hei Sook
Published: January 2007

Triacylglycerol (TAG) stored in adipose tissue can be rapidly mobilized by the hydrolytic action of lipases, with the release of fatty acids (FA) that are used by other tissues during times of energy deprivation. Unlike synthesis of TAG, which occurs not only in adipose tissue but also in other tissues such as liver for very-low-density lipoprotein formation, hydrolysis of TAG, lipolysis, predominantly occurs in adipose tissue. Until recently, hormone-sensitive lipase was considered to be the key rate-limiting enzyme responsible for regulating TAG mobilization. However, recent studies on hormone-sensitive lipase-null mice have challenged such a concept. A novel lipase named desnutrin/ATGL has been recently discovered to play a key role in lipolysis in adipocytes. Lipolysis is under tight hormonal regulation. Although opposing regulation of lipolysis in adipose tissue by insulin and catecholamines is well understood, autocrine/paracrine factors may also participate in its regulation. Intricate cooperation of these endocrine and autocrine/paracrine factors leads to a fine regulation of lipolysis in adipocytes, needed for energy homeostasis. In this review, we summarize and discuss the recent progress made in the regulation of adipocyte lipolysis.
Role of renal sympathetic nerve activity in hypertension induced by chronic nitric oxide inhibition
Authors: Ramchandra Rohit , Barrett Carolyn J. , Guild Sarah-Jane , McBryde Fiona , Malpas Simon C.
Published: January 2007

Nitric oxide levels are diminished in hypertensive patients, suggesting nitric oxide might have an important role to play in the development of hypertension. Chronic blockade of nitric oxide leads to hypertension that is sustained throughout the period of the blockade in baroreceptor-intact animals. It has been suggested that the sympathetic nervous system is involved in the chronic increase in blood pressure; however, the evidence is inconclusive. We measured renal sympathetic nerve activity and blood pressure via telemetry in rabbits over 7 days of nitric oxide blockade. Nitric oxide blockade via Nω-nitro-l-arginine methyl ester (l-NAME) in the drinking water (50 mg·kg−1·day−1) for 7 days caused a significant increase in arterial pressure (7 ± 1 mmHg above control levels; P < 0.05). While the increase in blood pressure was associated with a decrease in heart rate (from 233 ± 6 beats/min before the l-NAME to 202 ± 6 beats/min on day 7), there was no change in renal sympathetic nerve activity (94 ± 4 %baseline levels on day 2 and 96 ± 5 %baseline levels on day 7 of l-NAME; baseline nerve activity levels were normalized to the maximum 2 s of nerve activity evoked by nasopharyngeal stimulation). The lack of change in renal sympathetic nerve activity during the l-NAME-induced hypertension indicates that the renal nerves do not mediate the increase in blood pressure in conscious rabbits.
Maternal obesity increases hypothalamic leptin receptor expression and sensitivity in juvenile obesity-prone rats
Authors: Gorski Judith N. , Dunn-Meynell Ambrose A. , Levin Barry E.
Published: January 2007

In rats selectively bred to develop diet-induced obesity (DIO) or to be diet-resistant (DR), DIO maternal obesity selectively enhances the development of obesity and insulin resistance in their adult offspring. We postulated that the interaction between genetic predisposition and factors in the maternal environment alter the development of hypothalamic peptide systems involved in energy homeostasis regulation. Maternal obesity in the current studies led to increased body and fat pad weights and higher leptin and insulin levels in postnatal day 16 offspring of both DIO and DR dams. However, by 6 wk of age, most of these intergroup differences disappeared and offspring of obese DIO dams had unexpected increases in arcuate nucleus leptin receptor mRNA, peripheral insulin sensitivity, diet- and leptin-induced brown adipose temperature increase and 24-h anorectic response compared with offspring of lean DIO, but not lean DR dams. On the other hand, while offspring of obese DIO dams did have the highest ventromedial nucleus melanocortin-4 receptor expression, their anorectic and brown adipose thermogenic responses to the melanocortin agonist, Melanotan II (MTII), did not differ from those of offspring of lean DR or DIO dams. Thus, during their rapid growth phase, juvenile offspring of obese DIO dams have alterations in their hypothalamic systems regulating energy homeostasis, which ameliorates their genetic and perinatally determined predisposition toward leptin resistance. Because they later go onto become more obese, it is possible that interventions during this time period might prevent the subsequent development of obesity.
Modest weight gain is associated with sympathetic neural activation in nonobese humans
Authors: Gentile Christopher L. , Orr Jeb S. , Davy Brenda M. , Davy Kevin P.
Published: January 2007

We tested the hypothesis that modest, overfeeding-induced weight gain would increase sympathetic neural activity in nonobese humans. Twelve healthy males (23 ± 2 years; body mass index, 23.8 ± 0.7) were overfed ∼1,000 kcal/day until a 5-kg weight gain was achieved. Muscle sympathetic nerve activity (MSNA, microneurography), blood pressure, body composition (dual energy X-ray absorptiometry), and abdominal fat distribution (computed tomography) were measured at baseline and following 4 wk of weight stability at each individual's elevated body weight. Overfeeding increased body weight (73.5 ± 3.1 vs. 78.4 ± 3.2 kg, P < 0.001) and body fat (14.9 ± 1.2 vs. 18 ± 1.1 kg, P < 0.001) in 42 ± 8 days. Total abdominal fat increased (220 ± 22 vs. 266 ± 22 cm2, P < 0.001) with weight gain, due to increases in both subcutaneous (158 ± 15 vs. 187 ± 12 cm2, P < 0.001) and visceral fat (63 ± 8 vs. 79 ± 12 cm2, P = 0.004). As hypothesized, weight gain elicited increases in MSNA burst frequency (32 ± 2 vs. 38 ± 2 burst/min, P = 0.002) and burst incidence (52 ± 4 vs. 59 ± 3 bursts/100 heart beats, P = 0.026). Systolic, but not diastolic blood pressure increased significantly with weight gain. The change in MSNA burst frequency was correlated with the percent increase in body weight ( r = 0.59, P = 0.022), change in body fat ( r = 0.52, P = 0.043) and percent change in body fat ( r = 0.51, P = 0.045). The results of the current study indicate that modest diet-induced weight gain elicits sympathetic neural activation in nonobese males. These findings may have important implications for understanding the link between obesity and hypertension.
Internal Pallidal Neuronal Activity During Mild Drug-Related Dyskinesias in Parkinson's Disease: Decreased Firing Rates and Altered Firing Patterns
Authors: Lee J. I. , Verhagen Metman L. , Ohara S. , Dougherty P. M. , Kim J. H. , Lenz F. A.
Published: January 2007

The neuronal basis of hyperkinetic movement disorders has long been unclear. We now test the hypothesis that changes in the firing pattern of neurons in the globus pallidus internus (GPi) are related to dyskinesias induced by low doses of apomorphine in patients with advanced Parkinson's disease (PD). During pallidotomy for advanced PD, the activity of single neurons was studied both before and after administration of apomorphine at doses just adequate to induce dyskinesias (21 neurons, 17 patients). After the apomorphine injection, these spike trains demonstrated an initial fall in firing from baseline. In nine neurons, the onset of on was simultaneous with that of dyskinesias. In these spike trains, the initial fall in firing rate preceded and was larger than the fall at the onset of on with dyskinesias. Among the three neurons in which the onset of on occurred before that of dyskinesias, the firing rate did not change at the time of onset of dyskinesias. After injection of apomorphine, dyskinesias during on with dyskinesias often fluctuated between transient periods with dyskinesias and those without. Average firing rates were not different between these two types of transient periods. Transient periods with dyskinesias were characterized by interspike interval (ISI) independence, stationary spike trains, and higher variability of ISIs. A small but significant group of neurons demonstrated recurring ISI patterns during transient periods of on with dyskinesias. These results suggest that mild dyskinesias resulting from low doses of apomorphine are related to both low GPi neuronal firing rates and altered firing patterns.
Postural Context Alters the Stability of Bimanual Coordination by Modulating the Crossed Excitability of Corticospinal Pathways
Authors: Carson Richard G. , Smethurst Christopher J. , Oytam Yalchin , de Rugy Aymar
Published: January 2007

The tendency for movements of the upper limbs to be drawn systematically toward one another and to follow similar spatiotemporal trajectories is well known. Although suppression of this tendency is integral to tasks of daily living, its exploitation may prove to be critical in the rehabilitation of acquired hemiplegias. In general, however, the task-related factors that determine the degree of coupling between the upper limbs and the mechanisms that mediate bilateral interactions between neural pathways projecting to the muscles of the arm and hand are not yet well understood. We present evidence that the postural context in which human participants perform upper limb movements determines the relative stability of patterns of bimanual coordination. Manipulation of the axes of rotation of forearm movements reversed the relative stability of simultaneous and alternating patterns of bimanual coordination. Transcranial magnetic stimulation of motor cortex revealed that these manipulations of postural context altered the crossed modulation of excitability in corticospinal pathways that arises from movement of the opposite limb. Furthermore, modulation of responses to electrical stimulation of the cervicomedullary junction indicated that crossed modulation was also expressed at the level of the spinal motoneurons. Our data support the view that crossed modulation of excitability in corticospinal pathways mediates the stability of bimanual coordination. Furthermore, task-related factors that are sufficient to give rise to changes in the stability of bimanual coordination are accompanied by crossed modulation of excitability at multiple levels of the neuraxis, indicative of a failure of inhibitory control.
Functional Roles of Kv1 Channels in Neocortical Pyramidal Neurons
Authors: Guan D. , Lee J. C. F. , Higgs M. H. , Spain W. J. , Foehring R. C.
Published: January 2007

Pyramidal neurons from layers II/III of somatosensory and motor cortex express multiple Kv1 α-subunits and a current sensitive to block by α-dendrotoxin (α-DTX). We examined functional roles of native Kv1 channels in these cells using current-clamp recordings in brain slices and current- and voltage-clamp recordings in dissociated cells. α-DTX caused a significant negative shift in voltage threshold for action potentials (APs) and reduced rheobase. Correspondingly, a ramp-voltage protocol revealed that the α-DTX–sensitive current activated at subthreshold voltages. AP width at threshold increased with successive APs during repetitive firing. The steady-state threshold width for a given firing rate was similar in control and α-DTX, despite an initially broader AP in α-DTX. AP voltage threshold increased similarly during a train of spikes under control conditions and in the presence of α-DTX. α-DTX had no effect on input resistance or resting membrane potential and modest effects on the amplitude or width of a single AP. Accordingly, experiments using AP waveforms (APWs) as voltage protocols revealed that α-DTX–sensitive current peaked late during the AP repolarization phase. Application of α-DTX increased the rate of firing to intracellular current injection and increased gain (multiplicative effects), but did not alter spike-frequency adaptation. Consistent with these findings, voltage-clamp experiments revealed that the proportion of outward current sensitive to α-DTX was highest during the interval between two APWs, reflecting slow deactivation kinetics at −50 mV. Finally, α-DTX did not alter the selectivity of pyramidal neurons for DC versus time-varying stimuli.
Functional Imaging Reveals Respiratory Network Activity During Hypoxic and Opioid Challenge in the Neonate Rat Tilted Sagittal Slab Preparation
Authors: Barnes Benjamin J. , Tuong Chi-Minh , Mellen Nicholas M.
Published: January 2007

In mammals, respiration-modulated networks are distributed rostrocaudally in the ventrolateral quadrant of the medulla. Recent studies have established that in neonate rodents, two spatially separate networks along this column—the parafacial respiratory group (pFRG) and the pre-Bötzinger complex (preBötC)—are hypothesized to be sufficient for respiratory rhythm generation, but little is known about the connectivity within or between these networks. To be able to observe how these networks interact, we have developed a neonate rat medullary tilted sagittal slab, which exposes one column of respiration-modulated neurons on its surface, permitting functional imaging with cellular resolution. Here we examined how respiratory networks responded to hypoxic challenge and opioid-induced depression. At the systems level, the sagittal slab was congruent with more intact preparations: hypoxic challenge led to a significant increase in respiratory period and inspiratory burst amplitude, consistent with gasping. At opioid concentrations sufficient to slow respiration, we observed periods at integer multiples of control, matching quantal slowing. Consistent with single-unit recordings in more intact preparations, respiratory networks were distributed bimodally along the rostrocaudal axis, with respiratory neurons concentrated at the caudal pole of the facial nucleus, and 350 microns caudally, at the level of the pFRG and the preBötC, respectively. Within these regions neurons active during hypoxia- and/or opioid-induced depression were ubiquitous and interdigitated. In particular, contrary to earlier reports, opiate-insensitive neurons were found at the level of the preBötC.
Lesions of Area 5 of the Posterior Parietal Cortex in the Cat Produce Errors in the Accuracy of Paw Placement During Visually Guided Locomotion
Authors: Lajoie Kim , Drew Trevor
Published: January 2007

We developed a novel locomotor task in which cats step over obstacles that move at a different speed from that of the treadmill on which the cat is walking: we refer to this as a visual dissociation locomotion task. Slowing the speed of the obstacle with respect to that of the treadmill sometimes led to a major change in strategy so that cats made two steps with the hindlimbs before stepping over the obstacle (double step strategy) instead of the single step (standard strategy) observed when the obstacle was at the same speed as the treadmill. In addition, in the step preceding the step over the obstacle, the paws were placed significantly closer to the obstacle in the visual dissociation task than when the treadmill and the obstacle were at the same speed. After unilateral lesion of area 5 of the posterior parietal cortex (PPC), the cats frequently hit the obstacle as they stepped over it, especially in the visual dissociation task. This locomotor deficit was linked to significant differences in the location in which the forelimbs were placed in the step preceding that over the obstacle compared with the prelesion control. Cats also frequently hit the obstacle with their hindlimbs even when the forelimbs negotiated the obstacle successfully; this suggests an important role for the posterior parietal cortex in the coordination of the forelimbs and hindlimbs. Together, these results suggest an important contribution of the PPC to the planning of visually guided gait modifications.
Group I Metabotropic Glutamate Receptors Are Differentially Expressed by Two Populations of Olfactory Bulb Granule Cells
Authors: Heinbockel Thomas , Hamilton Kathryn A. , Ennis Matthew
Published: January 2007

In the main olfactory bulb, several populations of granule cells (GCs) can be distinguished based on the soma location either superficially, interspersed with mitral cells within the mitral cell layer (MCL), or deeper, within the GC layer (GCL). Little is known about the physiological properties of superficial GCs (sGCs) versus deep GCs (dGCs). Here, we used patch-clamp recording methods to explore the role of Group I metabotropic glutamate receptors (mGluRs) in regulating the activity of GCs in slices from wildtype and mGluR−/− mutant mice. In wildtype mice, bath application of the selective Group I mGluR agonist DHPG depolarized and increased the firing rate of both GC subtypes. In the presence of blockers of fast synaptic transmission (APV, CNQX, gabazine), DHPG directly depolarized both GC subtypes, although the two GC subtypes responded differentially to DHPG in mGluR1−/− and mGluR5−/− mice. DHPG depolarized sGCs in slices from mGluR5−/− mice, although it had no effect on sGCs in slices from mGluR1−/− mice. By contrast, DHPG depolarized dGCs in slices from mGluR1−/− mice but had no effect on dGCs in slices from mGluR5−/− mice. Previous studies showed that mitral cells express mGluR1 but not mGluR5. The present results therefore suggest that sGCs are more similar to mitral cells than dGCs in terms of mGluR expression.