bluuebunny/crossref_metadata_2025 huggingface dataset:
PERTURBATIONS IN BOUNCING COSMOLOGICAL MODELS
Authors: NETO NELSON PINTO
Published: September 2004

I describe the features and general properties of bouncing models and the evolution of cosmological perturbations on such backgrounds. I will outline possible observational consequences of the existence of a bounce in the primordial Universe and I will make a comparison of these models with standard long inflationary scenarios.
QUARK–GLUON PLASMA IN A BAG MODEL WITH A SOFT SURFACE
Authors: JACOBSEN RAFAEL B. , MARRANGHELLO GUILHERME F. , VASCONCELLOS CÉSAR A. Z. , MESQUITA ALEXANDRE
Published: September 2004

We analyze the implications of quantum hadrodynamics (QHD) and quantum chromodynamics (QCD) to model, respectively, two distinct phases of nuclear matter, a baryon–meson phase and a quark–gluon phase. We develop an equation of state (EoS) in the framework of a quark–meson coupling model for the hadron–meson phase using a new version of the fuzzy bag model with scalar–isoscalar, vector–isoscalar and vector–isovector meson–quark couplings and leptonic degrees of freedom as well as the constrains from chemical equilibrium, baryon number and electric charge conservation. We model the EoS for the QGP phase for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas as determined by thermodynamics. Our predictions yield the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature. Our results are slightly modified in comparison to predictions based on the standard MIT bag model with a constant bag pressure B.
HOW MATTER IS CREATED IN VSL THEORY?
Authors: NASCIMENTO RICARDO B. , CÂMARA CALISTRATO S. , CARVALHO JOEL C.
Published: September 2004

In this work we investigate matter creation in the context of two types of varying speed of light (VSL) cosmologies. We write the energy conservation law arising from Einstein equations for a Friedmann–Robertson–Walker (FRW) line element in a flat universe, solve the field equations and study how particles are created as c changes with cosmic epoch. We calculate the "adiabatic" particle creation rate, the total number of particle as a function of time and find the constrains imposed by the second law of thermodynamics upon the models.
CHARGED POLYTROPIC STARS AND A GENERALIZATION OF LANE–EMDEN EQUATION
Authors: PICANÇO RODRIGO , MALHEIRO MANOEL , RAY SUBHARTHI
Published: September 2004

In this paper we discuss charged stars with polytropic equation of state, where we derive an equation analogous to the Lane–Endem equation. We assume that these stars are spherically symmetric, and the electric field have only the radial component. First we review the field equations for such stars and then we proceed with the analog of the Lane–Emden equation for a polytropic Newtonian fluid and their relativistic equivalent (Tooper, 1964).1 These kind of equations are very interesting because they transform all the structure equations of the stars in a group of differential equations which are much more simple to solve than the source equations. These equations can be solved numerically for some boundary conditions and for some initial parameters. For this we assume that the pressure caused by the electric field obeys a polytropic equation of state too.
PERTURBATIVE BREAKING OF THE PSEUDOSPIN SYMMETRY IN THE RELATIVISTIC HARMONIC OSCILLATOR
Authors: LISBOA RONAI , MALHEIRO MANOEL , de CASTRO A. S. , ALBERTO P. , FIOLHAIS MANOEL
Published: September 2004

We show that relativistic mean fields theories with scalar S, and vector V, quadratic radial potentials can generate a harmonic oscillator with exact pseudospin symmetry and positive energy bound states when S=-V. The eigenenergies are quite different from those of the non-relativistic harmonic oscillator. We also discuss a mechanism for perturbatively breaking this symmetry by introducing a tensor potential. Our results shed light into the intrinsic relativistic nature of the pseudospin symmetry, which might be important in high density systems such as neutron stars.
OBSERVABLES FROM LARGE EXTRA DIMENSIONS
Authors: HOSSENFELDER SABINE , BLEICHER MARCUS , STÖCKER HORST
Published: September 2004

The existence of extra dimensions and a minimal length scale are modifications of our spacetime which are suggested by string theory. In models with additional dimensions, the Planck scale can be lowered to values accessible by future colliders and in ultra high energetic cosmic rays. Effective theories which extend beyond the standard-model by including extra dimensions and a minimal length allow the computation of observables and can be used to make testable predictions. Expected effects that arise within these models are the production of gravitons and black holes. Furthermore, the Planck length is a lower bound to the possible resolution of spacetime which might be reached soon.
STOCHASTIC STABILIZATION OF CHAOS AND THE COSMIC MICROWAVE BACKGROUND
Authors: DETTMANN C. P. , KEATING J. P. , PRADO SANDRA D.
Published: September 2004

The cosmic microwave background (CMB) is a contemporary echo of the Big Bang. The recently announced WMAP 1-year sky maps1 provide exceptionally accurate data for the CMB, making it possible to probe the physics of the early Universe down to an unprecedented level of detail. Fluctuations in the CMB have a distribution that is close to Gaussian (i.e. normal).2 There has been considerable interest in identifying physical mechanisms that might lead to deviations from the Gaussian distribution.2,3 One class of cosmological models that have been much studied are those in which the Universe has constant negative curvature; all photon trajectories are then exponentially unstable and the Gaussian distribution of the CMB fluctuations has been related to general properties of quantum wave-functions in chaotic systems.4–6 Inhomogeneities in the distribution of matter imply a non-constant curvature. Here we show that, surprisingly, random perturbations in the curvature can stabilize photon trajectories. We argue that this leads to quantifiable non-Gaussian fluctuations in the CMB, as well as having other potentially important cosmological consequences.
EFFECTIVE GEOMETRY IN ASTROPHYSICS
Authors: Bergliaffa Santiago E. Perez
Published: September 2004

The effective metric is introduced by means of two examples (non-linear electromagnetism and hydrodynamics), along with applications in Astrophysics. A sketch of the generality of the effect is also given.
NONLINEAR σ, δ DERIVATIVE SELF-COUPLINGS IN A RMFT FOR NEUTRON STARS
Authors: ROCHA SÉRGIO S. , RAZEIRA MOISÉS , VASCONCELLOS CÉSAR A. Z. , DILLIG MANFRED
Published: September 2004

We study dense hadronic matter in a generalized relativistic mean field approach which contains nonlinear couplings of the σ, ω, ϱ, δ fields and compare its predictions for properties of neutron stars with the corresponding results from different models found in the literature. Our predictions indicate a substantial modification in static global properties of nuclear matter and neutron stars with the inclusion of the δ meson into the formalism.
WHITE DWARFS AS LABORATORIES
Authors: KEPLER S. O.
Published: September 2004

As 98% of all stars evolve into white dwarf starsm their study tell us about the evolution of the majority of stars. White dwarf stars show luminosity variations when their temperature reach instabilitity strips caused by high surface opacity. These variations are due to global pulsations that can be used to study the internal structure and evolution of the stars. Their observations can be used as laboratories to test physical theories at high density and temperature.
THE ROLE OF THE NUCLEAR MATTER COMPRESSION MODULUS IN NEUTRON STARS
Authors: DEXHEIMER VERÔNICA A. , VASCONCELLOS CÉSAR A. Z. , RAZEIRA MOISÉS , DILLIG MANFRED
Published: September 2004

For the nuclear many body problem at high densities, formulated in the framework of a relativistic mean-field theory, we investigate in detail the compression modulus of nuclear matter as a function of the effective nucleon mass. We include consistently in our modelling chemical equilibrium as well as baryon number and electric charge conservation and investigate properties of neutron stars. Among other predictions we focus on the dependence of the maximum mass of a sequence of neutron stars as a function of the compression modulus and the nucleon effective mass.
VACUUM: MATTER AND ANTIMATTER
Authors: GREINER WALTER , BÜRVENICH THOMAS J.
Published: September 2004

In this manuscript we first present the vacuum for the e+-e- field of QED and show how it is modified for baryons in nuclear environment. Then we discuss the possibility of producing new types of nuclear systems by implanting an antibaryon into ordinary nuclei. The structure of nuclei containing one antiproton or antilambda is investigated within the framework of a relativistic mean-field model. Self-consistent calculations predict an enhanced binding and considerable compression in such systems as compared with normal nuclei. We present arguments that the life time of such nuclei with respect to the antibaryon annihilation might be long enough for their observation.
INTERNATIONAL WORKSHOP ON ASTRONOMY AND RELATIVISTIC ASTROPHYSICS: CONCLUDING REMARKS
Authors: HORVATH J. E.
Published: September 2004

We give a brief (and biased) summary of the main results presented in the Workshop (relativistic astrophysics, cosmology and gravitation), and some suggestions for future editions.
Overexpression of mutated Cu,Zn-SOD in neuroblastoma cells results in cytoskeletal change
Authors: Takamiya Rina , Takahashi Motoko , Park Yong Seek , Tawara Yoshie , Fujiwara Noriko , Miyamoto Yasuhide , Gu Jianguo , Suzuki Keiichiro , Taniguchi Naoyuki
Published: September 2004

Amyotrophic lateral sclerosis (ALS) involves the progressive degeneration of motor neurons in the spinal cord and the motor cortex. It has been shown that 15–20% of patients with familial ALS (FALS) have defects in the Sod1 gene, which encodes Cu,Zn-superoxide dismutase (SOD). To elucidate the pathological role of mutated Cu,Zn-SOD, we examined the issue of whether mutated Cu,Zn-SOD affects the cell cycle. Mouse neuroblastoma Neuro-2a cells were transfected with human wild-type or mutated (G37R, G93A) Cu,Zn-SOD. Mutated, Cu,Zn-SOD-transfected cells exhibited marked retardation in cell growth and G2/M arrest. They also displayed lower reactivity to phalloidin, indicating that the cytoskeleton was disrupted. Immunoprecipitation, two-dimensional gel electrophoresis, and Western blot analysis indicated that mutated Cu,Zn-SOD associates with actin. Similar results were obtained by in vitro incubation experiments with purified actin and mutated Cu,Zn-SOD (G93A). These results suggest that mutated Cu,Zn-SOD in FALS causes cytoskeletal changes by associating with actin, which subsequently causes G2/M arrest and growth retardation.
Interleukin-13 augments transforming growth factor-β1-induced tissue inhibitor of metalloproteinase-1 expression in primary human airway fibroblasts
Authors: Zhou XiuXia , Trudeau John B. , Schoonover Kathryn J. , Lundin Jessica I. , Barnes Steve M. , Cundall Meghan J. , Wenzel Sally E.
Published: September 2004

Tissue inhibitor of metalloproteinase (TIMP)-1 is a potent inhibitor of activated matrix metalloproteinases (MMPs) such as gelatinases and collagenases. TIMP-1 is induced by transforming growth factor-β1 (TGF-β1), but details regarding signaling pathways remain unclear. T-helper-2 cytokines also have profibrotic properties and can interact with TGF-β. In the present study, we examined the effects of interleukin (IL)-13 (2,500 pM) on TGF-β1 (200 pM)-induced expression of TIMP-1 mRNA and protein in primary human airway fibroblasts obtained from 57 human subjects. IL-13 alone had no effect on TIMP-1 mRNA or protein expression. However, IL-13 synergistically augmented TGF-β1-induced TIMP-1 mRNA and protein expression ( P < 0.001 vs. TGF-β1 alone). The upregulation of TIMP-1 by the combination of TGF-β1 and IL-13 involved increased transcription, with little effect on mRNA stabilization. Initial exploration of the pathways leading to the synergy determined that activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway by IL-13 may have a negative effect on TIMP-1 production. The specific PI3K inhibitor LY-294002 in the presence of TGF-β1, IL-13, or the combination of the two caused significant increases in TIMP-1 mRNA expression, while LY-294002 increased TIMP-1 protein levels in the presence of IL-13 alone. These results suggest that IL-13 augments TGF-β1-induced profibrotic responses at both the mRNA and protein levels. Although IL-13 induced activation of PI3K-Akt, the activation did not contribute to the synergy observed with TGF-β1 plus IL-13 in TIMP-1 expression and in fact may dampen it. The mechanisms behind the synergy remain to be determined.
Hypertonic shock inhibits growth factor receptor signaling, induces caspase-3 activation, and causes reversible fragmentation of the mitochondrial network
Authors: Copp Jeremy , Wiley Sandra , Ward Manus W. , van der Geer Peter
Published: September 2004

Hyperosmotic stress can be encountered by the kidney and the skin, as well as during treatment of acute brain damage. It can lead to cell cycle arrest or apoptosis. Exactly how mammalian cells detect hyperosmolarity and how the cell chooses between cell cycle arrest or death remains to be established. It has been proposed that hyperosmolarity is detected directly by growth factor receptor protein tyrosine kinases. To investigate this, we tested whether growth factors and osmotic stress cooperate in the activation of signaling pathways. Receptors responded normally to the presence of growth factors, and we observed normal levels of GTP-bound Ras under hyperosmotic conditions. In contrast, activation of Raf, Akt, ERK1, ERK2, and c-Jun NH2-terminal kinase was strongly reduced. These observations suggest that hyperosmotic conditions block signaling directly downstream of active Ras. It is thought that apoptotic cell death due to environmental stress is initiated by cytochrome c release from the mitochondria. Visualization of cytochrome c using immunofluorescence showed that hypertonic conditions result in a breakup of the mitochondrial network, which is reestablished within 1 h after hypertonic medium is replaced with isotonic medium. When we carried out live imaging, we observed that the mitochondrial membrane potential disappeared immediately after the onset of hyperosmotic shock. Our observations provide new insights into the hypertonic stress response pathway. In addition, they show that signaling downstream of Ras and mitochondrial dynamics can easily be manipulated by the exposure of cells to hyperosmotic conditions.
Conserved residues F316 and G476 in the concentrative nucleoside transporter 1 (hCNT1) affect guanosine sensitivity and membrane expression, respectively
Authors: Lai Yurong , Lee Eun-Woo , Ton Carl C. , Vijay Shashi , Zhang Huixia , Unadkat Jashvant D.
Published: September 2004

The functional significance of two highly conserved amino acid residues, F316 [putative transmembrane domain (TM)7] and G476 (putative TM11), in the concentrative nucleoside transporter hCNT1 (SLC28A1) was examined by performing site-directed mutagenesis. Conservative mutations at these positions (F316A, F316Y, G476A, and G476L) were generated and expressed in Madin-Darby canine kidney (MDCK) cells as fusion polypeptides with green fluorescent protein (GFP). Unlike wild-type hCNT1, G476A-GFP and G476L-GFP were not expressed in the plasma membrane in undifferentiated or differentiated MDCK cells and had no functional activity. Like wild-type hCNT1, F316A-GFP and F316Y-GFP were expressed in the plasma membrane of undifferentiated MDCK cells and in the apical membrane of differentiated MDCK cells. Remarkably, transport of [3H]uridine by F316Y-GFP or F316A-GFP was highly sensitive to inhibition by guanosine. Furthermore, genotyping of exon 11 of hCNT1 (TM7) in a panel of 260 anonymous human DNA samples revealed a novel F316H variant (TT>CA; 1/260). When expressed in MDCK cells, [3H]uridine transport by F316H was also found to be sensitive to inhibition by guanosine (IC50 = 148 μM). The effect of the F316H mutation resembles the N4 type nucleoside transporter phenotype previously reported to be present in human kidneys. We suggest that the N4 transport system is a naturally occurring variant of hCNT1, perhaps at the F316 position. Collectively, our data show that G476 is important for correct membrane targeting, folding, and/or intracellular processing of hCNT1. In addition, we have discovered that hCNT1 displays natural variation at position F316 and that the variant F316H confers on the transporter an unusual sensitivity to inhibition by guanosine.
Regulation of Kv4.3 currents by Ca2+/calmodulin-dependent protein kinase II
Authors: Sergeant Gerard P. , Ohya Susumu , Reihill James A. , Perrino Brian A. , Amberg Gregory C. , Imaizumi Yuji , Horowitz Burton , Sanders Kenton M. , Koh Sang Don
Published: September 2004

The voltage-dependent K+ channel 4.3 (Kv4.3) is one of the major molecular correlates encoding a class of rapidly inactivating K+ currents, including the transient outward current in the heart ( Ito) and A currents ( IA) in neuronal and smooth muscle preparations. Recent studies have shown that Ito in human atrial myocytes and IA in murine colonic myocytes are modulated by Ca2+/calmodulin-dependent protein kinase II (CaMKII); however, the molecular target of CaMKII in these studies has not been elucidated. We performed experiments to investigate whether CaMKII could regulate Kv4.3 currents directly. Inclusion of the autothiophosphorylated form of CaMKII in the patch pipette (10 nM) prolonged Kv4.3 currents such that the time required to reach 50% inactivation from peak more than doubled, with positive shifts in voltage dependence of both activation and inactivation. In contrast, the rate of recovery from inactivation was accelerated under these conditions. CaMKII-inhibitory peptide or KN-93 produced effects opposite to that above; thus the rate of inactivation was increased, and recovery from inactivation decreased. A number of mutagenesis experiments were conducted on the three candidate CaMKII consensus sequence sites on the channel. Mutations at S550A, located at the COOH-terminal region of the channel, resulted in currents that inactivated more rapidly but recovered from inactivation at a slower rate than that of wild-type controls. In addition, these currents were unaffected by dialysis with either autothiophosphorylated CaMKII or the specific inhibitory peptide of CaMKII, suggesting that CaMKII slows the inactivation and accelerates the rate of recovery from inactivation of Kv4.3 currents by a direct effect at S550A, located at the COOH-terminal region of the channel.
Role of Na+/Ca2+ exchange in regulating cytosolic Ca2+ in cultured human pulmonary artery smooth muscle cells
Authors: Zhang Shen , Yuan Jason X.-J. , Barrett Kim E. , Dong Hui
Published: September 2004

A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in pulmonary artery smooth muscle cells (PASMC) is an important stimulus for cell contraction, migration, and proliferation. Depletion of intracellular Ca2+ stores opens store-operated Ca2+ channels (SOC) and causes Ca2+ entry. Transient receptor potential (TRP) cation channels that are permeable to Na+ and Ca2+ are believed to form functional SOC. Because sarcolemmal Na+/Ca2+ exchanger has also been implicated in regulating [Ca2+]cyt, this study was designed to test the hypothesis that the Na+/Ca2+ exchanger (NCX) in cultured human PASMC is functionally involved in regulating [Ca2+]cyt by contributing to store depletion-mediated Ca2+ entry. RT-PCR and Western blot analyses revealed mRNA and protein expression for NCX1 and NCKX3 in cultured human PASMC. Removal of extracellular Na+, which switches the Na+/Ca2+ exchanger from the forward (Ca2+ exit) to reverse (Ca2+ entry) mode, significantly increased [Ca2+]cyt, whereas inhibition of the Na+/Ca2+ exchanger with KB-R7943 (10 μM) markedly attenuated the increase in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Store depletion also induced a rise in [Ca2+]cyt via the reverse mode of Na+/Ca2+ exchange. Removal of extracellular Na+ or inhibition of the Na+/Ca2+ exchanger with KB-R7943 attenuated the store depletion-mediated Ca2+ entry. Furthermore, treatment of human PASMC with KB-R7943 also inhibited cell proliferation in the presence of serum and growth factors. These results suggest that NCX is functionally expressed in cultured human PASMC, that Ca2+ entry via the reverse mode of Na+/Ca2+ exchange contributes to store depletion-mediated increase in [Ca2+]cyt, and that blockade of the Na+/Ca2+ exchanger in its reverse mode may serve as a potential therapeutic approach for treatment of pulmonary hypertension.
Protection against acute pancreatitis by activation of protease-activated receptor-2
Authors: Sharma Anupriya , Tao Xiaohong , Gopal Arun , Ligon Brooke , Andrade-Gordon Patricia , Steer Michael L. , Perides George
Published: September 2004

Protease-activated receptor-2 (PAR-2) is a widely expressed tethered ligand receptor that can be activated by trypsin and other trypsin-like serine proteases. In the exocrine pancreas, PAR-2 activation modulates acinar cell secretion of digestive enzymes and duct cell ion channel function. During acute pancreatitis, digestive enzyme zymogens, including trypsinogen, are activated within the pancreas. We hypothesized that trypsin, acting via PAR-2, might regulate the severity of that disease, and to test this hypothesis, we examined the effect of either genetically deleting or pharmacologically activating PAR-2 on the severity of secretagogue-induced experimental pancreatitis. We found that experimental acute pancreatitis is more severe in PAR-2−/− than in wild-type mice and that in vivo activation of PAR-2, achieved by parenteral administration of the PAR-2-activating peptide SLIGRL-NH2, reduces the severity of pancreatitis. In the pancreas during the early stages of pancreatitis, the MAPK ERK1/2 is activated and translocated to the nucleus, but nuclear translocation is reduced by activation of PAR-2. Our findings indicate that PAR-2 exerts a protective effect on pancreatitis and that activation of PAR-2 ameliorates pancreatitis, possibly by inhibiting ERK1/2 translocation to the nucleus. Our observations suggest that PAR-2 activation may be of therapeutic value in the treatment and/or prevention of severe clinical pancreatitis, and they lead us to speculate that, from a teleological standpoint, PAR-2 may have evolved in the pancreas as a protective mechanism designed to dampen the injurious effects of intrapancreatic trypsinogen activation.
Postnatal modulation of prenatally programmed hypertension by dietary Na and ACE inhibition
Authors: Manning Jennifer , Vehaskari V. Matti
Published: September 2004

Adult hypertension in the rat can be programmed experimentally by changes in intrauterine environment. The offspring typically do not become hypertensive until 6 to 8 wk of age, and recent evidence suggests that renal dysfunction may participate in the pathogenesis. The present study was based on the hypothesis that the window for programming extends to the postnatal period in the rat. Adult hypertension was induced by maternal low-protein diet during the second half of gestation. After being weaned at 3 wk, the offspring were exposed to one of the following regimens for the subsequent 3 wk: 1) low-Na diet, 2) standard Na diet, 3) high-Na diet, and 4) standard Na diet with enalapril. The pups were followed for 10 wk after discontinuation of the treatments. The brief exposure to low-Na diet or enalapril totally prevented the development of hypertension and the effect lasted throughout the observation period. The development of hyperreninemia, present in the standard Na group at 16 wk of age, was abolished in the low-Na and enalapril groups. Conversely, 3-wk exposure to high-Na diet increased the severity of the later hypertension and did not prevent the hyperreninemia. The findings suggest that there is a period of susceptibility during which prenatally programmed hypertension can be modulated postnatally, possibly coinciding with a critical stage in renal maturation.
Effects of water deprivation and rehydration on c-Fos and FosB staining in the rat supraoptic nucleus and lamina terminalis region
Authors: Ji Lisa L. , Fleming Tiffany , Penny Maurice L. , Toney Glenn M. , Cunningham J. Thomas
Published: September 2004

We studied cFos and FosB staining in the supraoptic nucleus (SON) the organum vasculosum of the lamina terminalis (OVLT) and the median preoptic nucleus (MnPO) in adult male rats after water deprivation (24 h, n = 11; 48 h, n = 12) and water deprivation with rehydration (22 h + water, n = 11; 46 h + water, n = 10). Control rats ( n = 15) had water available ad libitum. Separate sets of serial sections from each brain were processed for immunocytochemistry using primary antibodies against either c-Fos or FosB protein. Plasma osmolality, vasopressin, hematocrit, and plasma proteins were measured in separate groups ( n = 6–7). The number of c-Fos-positive cells in the SON was significantly increased after 24 and 48 h of water deprivation. In contrast, rehydrated groups were not different from control. Water deprivation significantly increased c-Fos staining in both the OVLT and the MnPO, but c-Fos staining was not altered by rehydration. FosB staining in the SON was significantly increased only by 48-h water deprivation, and this effect was significantly decreased by rehydration. In the MnPO and OVLT, FosB staining was significantly increased by water deprivation, and, like c-Fos staining, these increases were not affected by rehydration. Water deprivation significantly increased osmolality and hematocrit, as well as plasma protein and vasopressin concentrations. Plasma measurements from rehydrated rats were not different from control. We conclude that water deprivation and rehydration differentially affect c-Fos and FosB staining in a region-dependent manner.
Latencies of Climbing Fiber Inputs to Turtle Cerebellar Cortex
Authors: Ariel Michael
Published: September 2004

Responses of separate regions of rat cerebellar cortex (Cb) to inferior olive (IO) stimulation occur with the same latency despite large differences in climbing fiber (CF) lengths. Here, the olivocerebellar path of turtle was studied because its Cb is an unfoliated sheet on which measurements of latency and CF length can be made directly across its entire surface in vitro. During extracellular DC recordings at a given Cb position below the molecular layer, IO stimulation evoked a large negative field potential with a half-width duration of ∼6.5 ms. On this response were smaller oscillations similar to complex spikes. The stimulating electrode was moved to map the IO and the CF path from the brain stem to the Cb. The contralateral brain stem region that evoked these responses was tightly circumscribed within the medulla, lateral and deep to the obex. This response remained when the brain stem was bathed in solutions that blocked synaptic transmission. The Cb response to IO stimulation had a peak latency of ∼10 ms that was not dependent on the position of the recording electrode across the entire 8-mm rostrocaudal length of the Cb. However, for a constant Cb recording position, moving the stimulation across the midline to the ipsilateral brain stem and along the lateral wall of the fourth ventricle toward the peduncle did shorten the response latency. Therefore a synchronous Cb response to CF stimulation seems to be caused by changes in its conduction velocity within the entire cerebellar cortex but not within the brain stem.
Kappa Opioids Inhibit Physiologically Identified Medullary Pain Modulating Neurons and Reduce Morphine Antinociception
Authors: Meng I. D. , Johansen J. P. , Harasawa I. , Fields H. L.
Published: September 2004

Microinjection of kappa opioid receptor (KOR) agonists into the rostral ventromedial medulla (RVM) attenuates mu-opioid receptor mediated antinociception and stress-induced analgesia, yet is also reported to have an analgesic effect. To determine how KOR agonists produce both antinociceptive and antianalgesic actions within the RVM, the KOR agonist U69593 was microinjected directly into the RVM while concurrently monitoring tail flick latencies and RVM neuronal activity. Among RVM neurons recorded in vivo, two types show robust changes in activity just prior to the nocifensive tail flick reflex: on cells burst just prior to a tail flick and their activity is pronociceptive, whereas off cells pause just prior to the tail flick and their activity is antinociceptive. Although RVM microinjection of U69593 did not affect tail flick latencies on its own, it did attenuate the on cell burst, an effect blocked by co-injection of the KOR antagonist, nor-binaltorphimine (nor-BNI). Furthermore, U69593 inhibited ongoing activity in subsets of off cells (4/11) and neutral cells (3/9). Microinjection of U69593 into the RVM also attenuated morphine antinociception and suppressed the excitation of off cells. Together with previous in vivo and in vitro studies, these results are consistent with the idea that KOR agonists can be either pronociceptive through direct inhibition of off cells, or antianalgesic through both postsynaptic inhibition and presynaptic inhibition of glutamate inputs to RVM off cells.
Blocking the Anoxic Depolarization Protects Without Functional Compromise Following Simulated Stroke in Cortical Brain Slices
Authors: Anderson Trent R. , Jarvis Cathryn R. , Biedermann Alyson J. , Molnar Christine , Andrew R. David
Published: September 2004

Within 2 min of stroke onset, neurons and glia in brain regions most deprived of blood (the ischemic core) undergo a sudden and profound loss of membrane potential caused by failure of the Na+/K+ ATPase pump. This anoxic depolarization (AD) represents a collapse in membrane ion selectivity that causes acute neuronal injury because neurons simply cannot survive the energy demands of repolarization while deprived of oxygen and glucose. In vivo and in live brain slices, the AD resists blockade by antagonists of neurotransmitter receptors (including glutamate) or by ion channel blockers. Our neuroprotective strategy is to identify AD blockers that minimally affect neuronal function. If the conductance underlying AD is not normally active, its selective blockade should not alter neuronal excitability. Imaging changes in light transmittance in live neocortical and hippocampal slices reveal AD onset, propagation, and subsequent dendritic damage. Here we identify several sigma-1 receptor ligands that block the AD in slices that are pretreated with 10–30 μM of ligand. Blockade prevents subsequent cell swelling, dendritic damage, and loss of evoked field potentials recorded in layers II/III of neocortex and in the CA1 region of hippocampus. Even when AD onset is merely delayed, electrophysiological recovery is markedly improved. With ligand treatment, evoked axonal conduction and synaptic transmission remain intact. The large nonselective conductance that drives AD is still unidentified but represents a prime upstream target for suppressing acute neuronal damage arising during the first critical minutes of stroke. Sigma receptor ligands provide insight to better define the properties of the channel responsible for anoxic depolarization. Video clips of anoxic depolarization and spreading depression can be viewed at http://anatomy.queensu.ca/faculty/andrew.cfm . 1
Dopamine D1-Receptors Modulate Lateral Inhibition Between Principal Cells of the Nucleus Accumbens
Authors: Taverna Stefano , Canciani Barbara , Pennartz Cyriel M. A.
Published: September 2004

One of the current hypotheses on dopamine in the physiology of motivation posits that this neurotransmitter regulates filtering and selection of inputs to the nucleus accumbens. The effects of dopamine (100 μM) and the D1-receptor agonist SKF 38393 (20–50 μM) on GABAergic synaptic transmission between pairs of principal cells of rat nucleus accumbens were studied by using simultaneous dual patch-clamp recordings in acutely prepared brain slices. Both compounds attenuated postsynaptic responses induced by presynaptic firing and this effect was reversed by the D1-receptor antagonist SCH 23390 (25 μM). This attenuating effect of dopamine D1-receptors may act to diminish competitive interactions between single projection neurons or ensembles in the nucleus accumbens.
Analysis and Design of Behavioral Experiments to Characterize Population Learning
Authors: Smith Anne C. , Stefani Mark R. , Moghaddam Bita , Brown Emery N.
Published: September 2004

In population learning studies, between-subject response differences are an important source of variance that must be characterized to identify accurately the features of the learning process common to the population. Although learning is a dynamic process, current population analyses do not use dynamic estimation methods, do not compute both population and individual learning curves, and use learning criteria that are less than optimal. We develop a state-space random effects (SSRE) model to estimate population and individual learning curves, ideal observer curves, and learning trials, and to make dynamic assessments of learning between two populations and within the same population that avoid multiple hypothesis tests. In an 80-trial study of an NMDA antagonist's effect on the ability of rats to execute a set-shift task, our dynamic assessments of learning demonstrated that both the treatment and control groups learned, yet, by trial 35, the treatment group learning was significantly impaired relative to control. We used our SSRE model in a theoretical study to evaluate the design efficiency of learning experiments in terms of the number of animals per group and number of trials per animal required to characterize learning differences between two populations. Our results demonstrated that a maximum difference in the probability of a correct response between the treatment and control group learning curves of 0.07 (0.20) would require 15 to 20 (5 to 7) animals per group in an 80 (60)-trial experiment. The SSRE model offers a practical approach to dynamic analysis of population learning and a theoretical framework for optimal design of learning experiments.
Staggered Development of GABAergic and Glycinergic Transmission in the MNTB
Authors: Awatramani Gautam B. , Turecek Rostislav , Trussell Laurence O.
Published: September 2004

Maturation of some brain stem and spinal inhibitory systems is characterized by a shift from GABAergic to glycinergic transmission. Little is known about how this transition is expressed in terms of individual axonal inputs and synaptic sites. We have explored this issue in the rat medial nucleus of the trapezoid body (MNTB). Synaptic responses at postnatal days 5–7 (P5–P7) were small, slow, and primarily mediated by GABAA receptors. By P8–P12, an additional, faster glycinergic component emerged. At these ages, GABAA, glycine, or both types of receptors mediated transmission, even at single synaptic sites. Thereafter, glycinergic development greatly accelerated. By P25, evoked inhibitory postsynaptic currents (IPSCs) were 10 times briefer and 100 times larger than those measured in the youngest group, suggesting a proliferation of synaptic inputs activating fast-kinetic receptors. Glycinergic miniature IPSCs (mIPSCs) increased markedly in size and decay rate with age. GABAergic mIPSCs also accelerated, but declined slightly in amplitude. Overall, the efficacy of GABAergic inputs showed little maturation between P5 and P20. Although gramicidin perforated-patch recordings revealed that GABA or glycine depolarized P5–P7 cells but hyperpolarized P14–P15 cells, the young depolarizing inputs were not suprathreshold. In addition, vesicle-release properties of inhibitory axons also matured: GABAergic responses in immature rats were highly asynchronous, while in older rats, precise, phasic glycinergic IPSCs could transmit even with 500-Hz stimuli. Thus development of inhibition is characterized by coordinated modifications to transmitter systems, vesicle release kinetics, Cl− gradients, receptor properties, and numbers of synaptic inputs. The apparent switch in GABA/glycine transmission was predominantly due to enhanced glycinergic function.
On some properties of Banach operators. II
Authors: Thaheem A. B. , Khan A. R.
Published: September 2004

Using the notion of a Banach operator, wehave obtained a
decompositional property of aHilbert space, and
the equality of two invertible boundedlinear multiplicative
operators on a normed algebra with identity.
Congruences in ordered pairs of partitions
Authors: Hammond Paul , Lewis Richard
Published: September 2004

Dyson defined the rank of a partition (as the first part minus
the number of parts) whilst investigating certain congruences in
the sequence p−1(n). The rank has been widely studied as
have been other statistics, such as the crank. In this paper a
“birank” is defined which relates to ordered pairs of
partitions, and is used in an elementary proof of a congruence in
p−2(n).
Lyapunov stability solutions of fractional integrodifferential equations
Authors: Momani Shaher , Hadid Samir
Published: September 2004

Lyapunov stability and asymptotic stability conditions for the
solutions of the fractional integrodiffrential equations
, 0 < α ≤ 1, with the initial condition x(α−1)(t0) = x0, have been investigated. Our methods are applications of
Gronwall′s lemma and Schwartz inequality.
A Combinatorial proof of a partition identity of Andrews and Stanley
Authors: Sills Andrew V.
Published: September 2004

In his paper, “On a partition function of Richard Stanley,” George Andrews
proves a certain partition identity analytically and asks for a
combinatorial proof.This paper provides the requested
combinatorial proof.
Some criteria for univalence of certain integral operators
Authors: Pescar Virgil , Owa Shigeyoshi
Published: September 2004

We derive some criteria for univalence of certain integral
operators for analytic functions in the open unit disk.
A Furi‐Pera theorem in Hausdorff topological spaces for acyclic maps
Authors: Agarwal Ravi P. , Dshalalow Jewgeni H. , O′Regan Donal
Published: September 2004

We present new Furi‐Pera theorems for acyclic maps between
topological spaces.
Logistic equation with the p‐Laplacian and constant yield harvesting
Authors: Oruganti Shobha , Shi Junping , Shivaji Ratnasingham
Published: September 2004

We consider the positive solutions of a quasilinear elliptic equation with p‐Laplacian, logistic‐type growth rate function, and a constant yield harvesting. We use sub‐super‐solution methods to prove the existence of a maximal positive solution when the harvesting rate is under a certain positive constant.
On the discreteness of the spectra of the Dirichlet and Neumann p‐biharmonic problems
Authors: Benedikt Jiří
Published: September 2004

We are interested in a nonlinear boundary value problem for in [0, 1], p > 1, with Dirichlet and Neumann boundary conditions. We prove that eigenvalues of the Dirichlet problem are positive, simple, and isolated, and form an increasing unbounded sequence. An eigenfunction, corresponding to the nth eigenvalue, has precisely n − 1 zero points in (0, 1). Eigenvalues of the Neumann problem are nonnegative and isolated, 0 is an eigenvalue which is not simple, and the positive eigenvalues are simple and they form an increasing unbounded sequence. An eigenfunction, corresponding to the nth positive eigenvalue, has precisely n + 1 zero points in (0, 1).
A free boundary problem describing the saturated‐unsaturated flow in a porous medium
Authors: Marinoschi Gabriela
Published: September 2004

This paper presents a functional approach to a nonlinear model describing the complete physical process of water infiltration into an unsaturated soil, including the saturation occurrence and the advance of the wetting front. The model introduced in this paper involves a multivalued operator covering the simultaneous saturated and unsaturated flow behaviors and enhances the study of the displacement of the free boundary between these two flow regimes. The model resides in Richards′ equation written in pressure form with an initial condition and boundary conditions which in this work express the inflow due to the rain on the soil surface on the one hand, and characterize a certain permeability corresponding to the underground boundary, on the other hand. Existence, uniqueness, and regularity results for the transformed model in diffusive form, that is, for the moisture of the soil, and the existence of the weak solution for the pressure form are proved in the 3D case. The main part of the paper focuses on the existence of the free boundary between the saturated and unsaturated parts of the soil, and this is proved, in the 1D case, for certain stronger assumptions on the initial data and boundary conditions.
Osteogenic Cells Derived From Embryonic Stem Cells Produced Bone Nodules in Three‐Dimensional Scaffolds
Authors: Chaudhry G. R. , Yao D. , Smith A. , Hussain A.
Published: September 2004

An approach for 3D bone tissue generation from embryonic stem (ES) cells was investigated. The ES cells were induced to differentiate into osteogenic precursors, capable of proliferating and subsequently differentiating into bone‐forming cells. The differentiated cells and the seeded scaffolds were characterized using von Kossa and Alizarin Red staining, electron microscopy, and RT‐PCR analysis. The results demonstrated that ES‐derived bone‐forming cells attached to and colonized the biocompatible and biodegradable scaffolds. Furthermore, these cells produced bone nodules when grown for 3–4 weeks in mineralization medium containing ascorbic acid and beta‐glycerophosphate both in tissue culture plates and in scaffolds. The differentiated cells also expressed osteospecific markers when grown both in the culture plates and in 3D scaffolds. Osteogenic cells expressed alkaline phosphatase, osteocalcin, and osteopontin, but not an ES cell‐specific marker, oct‐4. These findings suggest that ES cell can be used for in vitro tissue engineering and cultivation of graftable skeletal structures.
Retrotransposition‐Competent Human LINE‐1 Induces Apoptosis in Cancer Cells With Intact p53
Authors: Haoudi Abdelali , Semmes O. John , Mason James M. , Cannon Ronald E.
Published: September 2004

Retrotransposition of human LINE‐1 (L1) element, a major representative non‐LTR retrotransposon in the human genome, is known to be a source of insertional mutagenesis. However, nothing is known about effects of L1 retrotransposition on cell growth and differentiation. To investigate the potential for such biological effects and the impact that human L1 retrotransposition has upon cancer cell growth, we examined a panel of human L1 transformed cell lines following a complete retrotransposition process. The results demonstrated that transposition of L1 leads to the activation of the p53‐mediated apoptotic pathway in human cancer cells that possess a wild‐type p53. In addition, we found that inactivation of p53 in cells, where L1 was undergoing retrotransposition, inhibited the induction of apoptosis. This suggests an association between active retrotransposition and a competent p53 response in which induction of apoptosis is a major outcome. These data are consistent with a model in which human retrotransposition is sensed by the cell as a “genetic damaging event” and that massive retrotransposition triggers signaling pathways resulting in apoptosis.
Intranasal steroids decrease eosinophils but not mucin expression in nasal polyps
Authors: Burgel P-R. , Cardell L.O. , Ueki I.F. , Nadel J.A.
Published: September 2004

Increased mucin expression is a feature of nasal polyposis. Corticosteroids reduce polyp size and symptoms, but their effect on mucin production remains unknown. In this study, the effects of intranasal corticosteroids on MUC5AC mucin expression, nasal resistance, eosinophil and neutrophil infiltration, epidermal growth factor receptor (EGFR), interleukin (IL)-8, and tumour necrosis factor (TNF)-α expression was assessed in nasal polyps.

In nine subjects, one nasal polyp was removed surgically before treatment and another was removed after 8 weeks of intranasal fluticasone (400 µg·day−1). Tissues were processed forin situhybridisation and immunohistochemical staining. Described effects of fluticasone on nasal polyps (reduction in nasal resistance and in eosinophil infiltration) were evaluated. Morphometric analysis was performed to assess the effect of fluticasone on epithelial-, MUC5AC-, EGFR- and IL-8-stained areas, TNF-α-stained cells, and neutrophil numbers.

Treatment with fluticasone decreased nasal resistance and intra-epithelial eosinophils. The MUC5AC-stained area in the epithelium was unchanged by treatment; MUC5AC mRNA expression was unaffected by treatment. EGFR-stained area, intra-epithelial neutrophil numbers, IL-8 and TNF-α expression were also unchanged by therapy.

Intranasal fluticasone was effective in decreasing nasal airflow resistance and intra-epithelial eosinophils but had no effect on mucin or epidermal growth factor receptor expression or on neutrophil recruitment.
Intravenousiloprost bridging to orthotopic liver transplantation in portopulmonary hypertension
Authors: Minder S. , Fischler M. , Muellhaupt B. , Zalunardo M.P. , Jenni R. , Clavien P-A. , Speich R.
Published: September 2004

Portopulmonary hypertension (PPHTN) is associated with poor prognosis and high perioperative mortality after orthotopic liver transplantation.

This study documents the first case of a patient with PPHTN who was successfully bridged to orthotopic liver transplantation withi.v.iloprost, a stable prostacyclin analogue. The PPHTN had resolved completely 4 months after successful transplantation.

In conclusion, portopulmonary hypertension is a relative contraindication to orthotopic liver transplantation, which should be attempted only if pulmonary haemodynamics improve with prostanoids. In this context, iloprost may be a valuable alternative to epoprostenol.
Role and regulation of interleukin-1 molecules in pro-asthmatic sensitised airway smooth muscle
Authors: Whelan R. , Kim C. , Chen M. , Leiter J. , Grunstein M.M. , Hakonarson H.
Published: September 2004

Interleukin (IL)-1β is a pleiotropic, pro-inflammatory cytokine that has been importantly implicated in driving the inflammatory response and resultant changes in airway smooth muscle (ASM) responsiveness in asthma. IL-1β belongs to a family of molecules, known as the IL-1 axis, which exert both pro- and anti-inflammatory effects. Since dysregulation of IL-1 axis molecules may be critical in the pathobiology of asthma, the present study examined the expression and activation of both the inhibitory and stimulatory IL-1 axis molecules in human ASM cells and their roles in modulating cytokine and immunoglobulin (Ig)E immune complex (IgE cx)-mediated changes in rabbit ASM constrictor and relaxant responsiveness.

The results demonstrate the following. 1) Pre-treatment of isolated rabbit tracheal rings with the inhibitory IL-1 axis members, IL-1 receptor antagonist and IL-1 type-II receptor abrogated both IL-5- and IgE cx-induced changes in ASM responsiveness. 2) Administration of IL-5, IL-1β and IgE cxs to human ASM cells increased mRNA and protein expressions of both stimulatory and inhibitory IL-1 axis molecules. 3) The time course of IL-5-induced IL-1 axis molecule expression preceded that of both IL-1β and IgE immune cxs.

Collectively, these findings suggest that modulation at the level of the interleukin-1 axis of molecules may have significant therapeutic potential in the treatment of asthma.