bluuebunny/crossref_metadata_2025 huggingface dataset:
MULTIPARTITE QUANTUM SYSTEMS: PHASES DO MATTER AFTER ALL
Authors: SÁNCHEZ-SOTO LUIS L. , KLIMOV ANDREI B. , de GUISE HUBERT
Published: May 2006

A comprehensive theory of phase for finite-dimensional quantum systems is developed. The only physical requirement imposed is that phase is complementary to amplitude. This complementarity is implemented by resorting to the notion of mutually unbiased bases. For a d-dimensional system, where d is a power of a prime, we explicitly construct d + 1 classes of maximally commuting operators, each one consisting of d - 1 operators. One of this class consists of diagonal operators that represent amplitudes and, by the finite Fourier transform, operators in this class are mapped to off-diagonal operators that can be appropriately interpreted as phases. The relevant example of a system of qubits is examined in detail.
FINITE GEOMETRIES IN QUANTUM THEORY: FROM GALOIS (FIELDS) TO HJELMSLEV (RINGS)
Authors: SANIGA METOD , PLANAT MICHEL
Published: May 2006

Geometries over Galois fields (and related finite combinatorial structures/algebras) have recently been recognized to play an ever-increasing role in quantum theory, especially when addressing properties of mutually unbiased bases (MUBs). The purpose of this contribution is to show that completely new vistas open up if we consider a generalized class of finite (projective) geometries, viz. those defined over Galois rings and/or other finite Hjelmslev rings. The case is illustrated by demonstrating that the basic combinatorial properties of a complete set of MUBs of a q-dimensional Hilbert space [Formula: see text], q = prwith p being a prime and r a positive integer, are qualitatively mimicked by the configuration of points lying on a proper conic in a projective Hjelmslev plane defined over a Galois ring of characteristic p2and rank r. The q vectors of a basis of [Formula: see text] correspond to the q points of a (so-called) neighbour class and the q + 1 MUBs answer to the total number of (pairwise disjoint) neighbour classes on the conic. Although this remarkable analogy is still established at the level of cardinalities only, we currently work on constructing an explicit mapping by associating a MUB to each neighbour class of the points of the conic and a state vector of this MUB to a particular point of the class. Further research in this direction may prove to be of great relevance for many areas of quantum information theory, in particular for quantum information processing.
CHIRPED PULSES, GAUSS SUMS AND THE FACTORIZATION OF NUMBERS
Authors: MERKEL WOLFGANG , CRASSER OLIVER , HAUG FLORIAN , LUTZ ERIC , MACK HOLGER , FREYBERGER MATTHIAS , SCHLEICH WOLFGANG P. , AVERBUKH ILYA , BIENERT MARC , GIRARD BERTRAND , MAIER HELMUT , PAULUS GERHARD G.
Published: May 2006

We present two physical systems which make Gauß sums experimentally accessible. The probability amplitude for a two-photon transition in an appropriate ladder system driven by a chirped laser pulse is determined by a Gauß sum. The autocorrelation function of a quantum rotor is also of the form of a Gauß sum. These examples suggest rules for determining prime factor components on the basis of the properties of Gauß sums. Moreover, we show how Gauß sums are related to the Riemann Zeta function.
SIMPLE MINIMAL INFORMATIONALLY COMPLETE MEASUREMENTS FOR QUDITS
Authors: WEIGERT STEFAN
Published: May 2006

Simple minimal but informationally complete positive operator-valued measures are constructed out of the expectation-value representation for qudits. Upon suitable modification, the procedure transforms any set of d2 linearly independent hermitean operators into such an observable. Minor changes in the construction lead to closed-form expressions for informationally complete positive measures in the spaces ℂd.
ROUGHNESS OF THE INTERFACES IN THE KARGAR–PARISI–ZHANG EQUATION
Authors: MA K. , YANG C. B.
Published: May 2006

The time evolution of the roughness is investigated for one-dimensional systems described by the Kargar–Parisi–Zhang equation. Scaling behavior of the roughness is studied, and the scaling function is obtained.
GROWTH MODEL OF TiC DENDRITIC CRYSTALS PRODUCED BY LASER SURFACE ALLOYING TECHNIQUE
Authors: TIAN Y. S. , CHEN C. Z. , CHEN L. X. , HUO Q. H.
Published: May 2006

Dendritic compounds usually have a bad effect on the mechanical properties of engineering materials. In this study, the microstructure and the growth model of TiC crystals fabricated by laser surface alloying of pure titanium are investigated by means of SEM, EMPA and TEM. Dendritic TiC develops into primary truck by the model of continuous growth at the beginning of solidification and thus the surfaces of the primary truck that are suited to grow laterally develop fully by the model of spiral growth to form a second branch with a faceted surface. Hence the final morphology of dendritic TiC looks like it consists of tiny crystal grains in a linear arrangement.
ON SUPERFLUIDITY AND SUPPRESSED LIGHT SCATTERING IN BECs
Authors: NAZARIO ZAIRA , SANTIAGO DAVID I.
Published: May 2006

We show that the suppression of light scattering off a Bose Einstein Condensate is equivalent to the Landau argument for superfluidity and thus is a consequence of the Principle of Superfluidity. The superfluid ground state of a BEC contains nonseparable, nontrivial correlations between the bosons that make up the system, i.e., it is entangled. The correlations in the ground state entangle the bosons into a coherent state for the lowest energy state. The entanglement is so extreme that the bosons that make up the system cannot be excited at long wavenumbers. Their existence at low energies is impossible. Only quantum sound can be excited, i.e. the excitations are Bogolyubov quasiparticles which do not resemble free bosons whatsoever at low energies. This means that the system is superfluid by the Landau argument and the superfluidity is ultimately the reason for suppressed scattering at low wavelengths.
LOCAL ORDER OF LIQUID AND UNDERCOOLED TRANSITION METAL BASED SYSTEMS: AB INITIO MOLECULAR DYNAMICS STUDY
Authors: JAKSE NOEL , PASTUREL ALAIN
Published: May 2006

An overview of a recent series of ab initio molecular dynamics (MD) simulations for pure liquid transition metals as well as for transition metals (TM) based liquid alloys is presented. The aim is to investigate the local structure of these systems and their evolution upon undercooling, and our results are analyzed through a three-dimensional picture of the short-ranger order (SRO) by means of the common-neighbor analysis. Recent diffraction experiments indicate that the structure of both pure metals and alloys in undercooled states is dominated by an icosahedral SRO. We find that the five-fold symmetry is already present in the liquid state of all the studied systems. However our findings show that the five-fold symmetry in the liquid state as well as its evolution upon undercooling depends on the system under consideration. For Ni , Zr , and Ta , local configurations are more complex than that given by the simple icosahedron. For Al 80 Ni 20 and Al 80 Mn 20 alloys, local configurations are the result of a strong competition between chemical and topological effects; the key role played by the occurrence of localized magnetic moments of Mn atoms to interpret their short-range arrangements is emphasized, and the time evolution of the configurations is examined in terms of the mean square displacements.
DYNAMICS OF SOME RATIONAL DISCRETE DYNAMICAL SYSTEMS VIA INVARIANTS
Authors: CIMA ANNA , GASULL ARMENGOL , MAÑOSA VÍCTOR
Published: May 2006

We consider several discrete dynamical systems for which some invariants can be found. Our study includes complex Möbius transformations as well as the third-order Lyness recurrence.
SHOOTING METHODS FOR LOCATING GRAZING PHENOMENA IN HYBRID SYSTEMS
Authors: DONDE VAIBHAV , HISKENS IAN A.
Published: May 2006

Hybrid systems are typified by strong coupling between continuous dynamics and discrete events. For such piecewise smooth systems, event triggering generally has a significant influence over subsequent system behavior. Therefore, it is important to identify situations where a small change in parameter values alters the event triggering pattern. The bounding case, which separates regions of (generally) quite different dynamic behaviors, is referred to as grazing. At a grazing point, the system trajectory makes tangential contact with an event triggering hypersurface. The paper formulates conditions governing grazing points. Both transient and periodic behaviors are considered. The resulting boundary value problems are solved using shooting methods that are applicable for general nonlinear hybrid (piecewise smooth) dynamical systems. The grazing point formulation underlies the development of a continuation process for exploring parametric dependence. It also provides the basis for an optimization technique that finds the smallest parameter change necessary to induce grazing. Examples are drawn from power electronics, power systems and robotics, all of which involve intrinsic interactions between continuous dynamics and discrete events.
IDENTICAL SYNCHRONIZATION OF CHAOTIC SYSTEMS
Authors: CHEN MAOYIN , ZHOU DONGHUA , SHANG YUN
Published: May 2006

We consider the problem of identical synchronization (IS) of chaotic systems in two cases: (i) system uncertainty exists in the drive system, and (ii) output uncertainty exists in the drive system. No matter which case it is, the IS problem can be resolved via the combination of unknown input observers (UIOs) and the linear matrix inequalities (LMIs). Theoretical analysis and numerical simulations verify our main results in this paper.
ANALYSIS OF PATTERN FORMATION IN CHAIN OF COUPLED BISTABLE ELEMENTS
Authors: KUZNETSOV A. S. , FORTI G. L. , SHALFEEV V. D.
Published: May 2006

One of the most complex problems of nonlinear dynamics is the investigation of collective dynamics of ensembles consisting of a large number of coupled elements. A number of investigations were carried out for linear coupling of diffusion (difference) type. Recently, based on successful investigations of neurobiological objects [Abarbanel et al., 1996], an interest has grown in the study of dynamics of ensembles with nonlinear, nondiffusion type of coupling. In this paper we address pattern formation in a chain of bistable elements so coupled [Kuznetsov & Shalfeev, 2000].
DETECTING BOGDANOV–TAKENS BIFURCATION OF TRAVELING WAVES IN REACTION–DIFFUSION SYSTEMS
Authors: GUBERNOV V. V. , SIDHU H. S. , MERCER G. N.
Published: May 2006

In this paper we investigate the onset of instabilities in a model describing the propagation of the steady planar premixed combustion wave. In particular, we are interested in determining the Bogdanov–Takens bifurcation condition, which is investigated semi-analytically. We derive an analytic condition for the existence of this type of bifurcation and based on this criterion we numerically determine the parameter values for which the Bogdanov–Takens bifurcation occurs. This numerical method is found to be more efficient than the previous methods.
A NOTE ON THE PHYSICS OF SOIL WATER RETENTION THROUGH FRACTAL PARAMETERS
Authors: MILLÁN H. , AGUILAR M. , DOMÌNGUEZ J. , CÈSPEDES L. , VELASCO E. , GÒNZALEZ M.
Published: May 2006

Fractals are important for studying the physics of water transport in soils. Many authors have assumed a mass fractal structure while others consider a fractal surface approach. Each model needs comparisons on the same data set in terms of goodness-of-fit and physical interpretation of parameters. In this note, it is shown, with some representative data sets, that a pore-solid interface fractal model could fit soil water retention data better than a mass fractal model. In addition to the interfacial fractal dimension, this model predicts the tension at dryness. This value is very close to 106 kPa as theoretically predicted.
FRACTAL DIMENSIONS FOR MULTIPHASE FRACTAL MEDIA
Authors: YU BOMING
Published: May 2006

The simple expressions for the fractal dimensions of multiphase fractal media are derived and are found to be a function of porosity, phase content, ratio of the maximum to minimum pore sizes. There is no any empirical constant in the proposed fractal dimensions. For the three-phase fractal porous medium or unsaturated porous medium, the fractal dimensions are found to be meaningful only in certain ranges of saturation Sw, i.e. Sw > S min for wetting phase and Sw < S max for non-wetting phase for a given porosity, based on real porous media for requirements from both fractal theory and experimental observations. The present analysis of the fractal dimensions is verified by a comparison with the existing experimental measurements. It allows for the analysis of transport properties such as permeability, thermal dispersion, and conductivities (both thermal and electrical) in multiphase fractal media by the proposed model.
Maternal high-fat diet consumption results in fetal malprogramming predisposing to the onset of metabolic syndrome-like phenotype in adulthood
Authors: Srinivasan Malathi , Katewa Subhash D. , Palaniyappan Arivazhagan , Pandya Jignesh D. , Patel Mulchand S.
Published: May 2006

Chronic consumption of a high-fat (HF) diet by female rats in their postweaning period resulted in significant increases in body weight and plasma levels of insulin, glucose, and triglycerides during pregnancy compared with female rats consuming a standard rodent laboratory chow (LC). On gestational day 21, plasma insulin levels and the insulin secretory response of islets to various secretogogues were significantly increased in HF fetuses. The HF male progeny weaned onto LC (HF/LC) demonstrated increases in body weight from postnatal day 60 onward. In adulthood, HF/LC male rats were significantly heavier than controls, had increased plasma levels of insulin, glucose, free fatty acids, and triglycerides, and demonstrated glucose intolerance. HF/LC male islets secreted increased amounts of insulin in response to low glucose concentrations, but their response to a high glucose concentration was similar to that of LC/LC islets. In another set of experiments, when the male progeny of HF female rats were weaned onto a high-sucrose diet (HF/HSu), their metabolic profile was further worsened. These results indicate that chronic consumption of a HF diet by female rats malprograms the male progeny for glucose intolerance and development of increased body weight in adulthood. The long-term high-fat feeding to female rats employed in this study bears resemblance to the dietary habits in Western societies. The results of this study implicate dietary practices of women in the etiology of the present epidemic of human obesity and related disorders.
Recombinant human follicle-stimulating hormone alters maternal ovarian hormone concentrations and the uterus and perturbs fetal development in mice
Authors: Kelley Rebecca L. , Kind Karen L. , Lane Michelle , Robker Rebecca L. , Thompson Jeremy G. , Edwards Lisa J.
Published: May 2006

Gonadotropins are routinely administered to produce multiple oocytes for clinical in vitro fertilization (IVF) treatment, laboratory research, and livestock industries. Studies in mice have shown gonadotropin stimulation using equine chorionic gonadotropin (eCG) affects the endometrium, implantation, and fetal development. Evidence from clinical studies also indicates that stimulation with recombinant human follicle-stimulating hormone (rhFSH) may be detrimental to the endometrium and implantation rates. We investigated the effect of rhFSH in mice on maternal plasma hormone concentrations and uterine gene and protein expression and the effect of a stimulated maternal environment on pregnancy. Adult females were stimulated with rhFSH or eCG, followed by human chorionic gonadotropin (hCG). On day 4 of pseudopregnancy, mice either had embryos transferred to the uterus or were killed, and blood and uterine samples were collected. Pregnancy outcomes were examined on day 15. Gonadotropin stimulation increased plasma progesterone concentrations on day 4 compared with controls, whereas estradiol concentrations were unaffected. Stimulation also reduced uterine leukemia inhibitory factor ( Lif) mRNA, but the expression of estrogen and progesterone receptors ( Esr1 and Pgr), homeobox gene Hoxa10, and Vegf mRNA were unchanged. Furthermore, distribution of uterine PGR protein expression was altered by stimulation, but LIF protein was unchanged. Stimulated embryo transfer recipients had lower pregnancy rates than controls, and fetuses from the rhFSH group had reduced weight, length, and maturity. These results demonstrate that gonadotropin stimulation with rhFSH or eCG alters the preimplantation maternal environment, which results in reduced pregnancy rates and fetal development in the mouse.
Exogenously imposed postprandial-like rises in systemic glucose and GLP-1 do not produce an incretin effect, suggesting an indirect mechanism of GLP-1 action
Authors: Ionut Viorica , Liberty Idit F. , Hucking Katrin , Lottati Maya , Stefanovski Darko , Zheng Dan , Bergman Richard N.
Published: May 2006

The insulinotropic intestinal hormone GLP-1 is thought to exert one of its effects by direct action on the pancreatic β-cell receptors. GLP-1 is rapidly degraded in plasma, such that only a small amount of the active form reaches the pancreas, making it questionable whether this amount is sufficient to produce a direct incretin effect. The aim of our study was to assess, in a dog model, the putative incretin action of GLP-1 acting directly on the β-cell in the context of postprandial rises in GLP-1 and glucose. Conscious dogs were fed a high-fat, high-carbohydrate meal, and insulin response was measured. We also infused systemic glucose plus GLP-1, or glucose alone, to simulate the meal test values of these variables and measured insulin response. The results were as follows: during the meal, we measured a robust insulin response (52 ± 9 to 136 ± 14 pmol/l, P < 0.05 vs. basal) with increases in portal glucose and GLP-1 but only limited increases in systemic glucose (5.3 ± 0.1 to 5.7 ± 0.1 mmol/l, P = 0.1 vs. basal) and GLP-1 (6 ± 0 to 9 ± 1 pmol/l, P = 0.5 vs. basal). Exogenous infusion of systemic glucose and GLP-1 produced a moderate increase in insulin (43 ± 5 to 84 ± 15 pmol/l, 43% of the meal insulin). However, infusion of glucose alone, without GLP-1, produced a similar insulin response (37 ± 6 to 82 ± 14 pmol, 53% of the meal insulin, P = 0.7 vs. glucose and GLP-1 infusion). In conclusion, in dogs with postprandial rises in systemic glucose and GLP-1, the hormone might not have a direct insulinotropic effect and could regulate glycemia via indirect, portohepatic-initiated neural mechanisms.
Assessment of postprandial glucose metabolism: conventional dual- vs. triple-tracer method
Authors: Toffolo Gianna , Basu Rita , Dalla Man Chiara , Rizza Robert , Cobelli Claudio
Published: May 2006

The dual-tracer method has been used conventionally for assessment of postprandial fluxes, i.e., appearance in plasma of ingested glucose (Ra meal), endogenous glucose production (EGP), and disposal (Rd). To quantify the magnitude of errors affecting the calculations and their dependence on model assumptions, this method was assessed and compared with the triple-tracer method, which provides model-independent estimates. For this purpose, the dual-tracer protocol was performed twice in eight normal subjects, with [1-13C]glucose to trace ingested glucose and [6,6-2H2]glucose constantly infused. A third tracer, [6-3H]glucose, was infused at variable rates to render the calculation of Ra meal and EGP virtually model independent. The dual-tracer method analyzed with a one-compartment model performed poorly, since Ra meal peak was significantly lower and delayed compared with triple-tracer reference, resulting in a significantly lower estimation of the amount of absorbed glucose (9,036 ± 558 vs. 11,316 ± 823 μmol/kg, P = 0.0117). EGP showed a paradoxical pattern, with an initial overshoot followed by a rapid decay to negative values, resulting in a significant underestimation of EGP suppression (57 ± 3 vs. 65 ± 4%, P = 0.0117). A two-compartment model performed better but did not overcome the limitations of the dual-tracer approach, since the amount of absorbed glucose was still significantly underestimated (10,231 ± 661 vs. 12,169 ± 838 μmol/kg, P = 0.0117) and EGP still showed a paradoxical behavior. Rd, estimated from Ra meal and EGP, was significantly underestimated with the dual-tracer method, irrespective of adopted model. We conclude that three suitably infused tracers are required for accurate assessment of postprandial Ra meal, EGP, and Rd.
Oculomotor Plasticity During Vestibular Compensation Does Not Depend on Cerebellar LTD
Authors: Faulstich M. , van Alphen A. M. , Luo C. , du Lac S. , De Zeeuw C. I.
Published: May 2006

Vestibular paradigms are widely used for investigating mechanisms underlying cerebellar motor learning. These include adaptation of the vestibuloocular reflex (VOR) after visual-vestibular mismatch training and vestibular compensation after unilateral damage to the vestibular apparatus. To date, various studies have shown that VOR adaptation may be supported by long-term depression (LTD) at the parallel fiber to Purkinje cell synapse. Yet it is unknown to what extent vestibular compensation may depend on this cellular process. Here we investigated adaptive gain changes in the VOR and optokinetic reflex during vestibular compensation in transgenic mice in which LTD is specifically blocked in Purkinje cells via expression of a peptide inhibitor of protein kinase C (L7-PKCi mutants). The results demonstrate that neither the strength nor the time course of vestibular compensation are affected by the absence of LTD. In contrast, analysis of vestibular compensation in spontaneous mutants that lack a functional olivo-cerebellar circuit ( lurchers) shows that this form of motor learning is severely impaired. We conclude that oculomotor plasticity during vestibular compensation depends critically on intact cerebellar circuitry but not on the occurrence of cerebellar LTD.
Associative Plasticity in Human Motor Cortex During Voluntary Muscle Contraction
Authors: Kujirai Kayoko , Kujirai Takashi , Sinkjaer Thomas , Rothwell John C.
Published: May 2006

TMS pulses over the hand area of motor cortex activate different subpopulations of synaptic connections if the direction of the induced current in the brain is reversed from posterior-anterior (PA) direction to anterior-posterior (AP). We tested whether this also made a difference to the after-effects of paired associative stimulation (PAS: ulnar nerve stimulation followed 25 ms later by a transcranial magnetic stimulation pulse). If 50 pairs of stimuli (0.1 Hz) were applied using conventional suprathreshold PA-PAS in resting subjects, there was no effect on motor-evoked potentials (MEPs) in the first dorsal interosseous muscle. In contrast if the same number of pulses were given while subjects made a small tonic (5% maximum) contraction, MEPs were facilitated and resting motor threshold reduced when AP but not PA pulses were used. Subsequent experiments employed subthreshold TMS (95% of the active motor threshold) during voluntary muscle contraction. MEP facilitation accompanied by reduced AP threshold occurred when PAS was given using AP pulses (AP-Sub-PAS), whereas PAS using PA pulses (PA-Sub-PAS) had no excitatory effect. There was no facilitation if the ulnar nerve stimulus was replaced by digital nerve stimulation. There was a tendency for short interval intracortical inhibition (SICI) to decrease and intracortical facilitation (ICF) to increase after AP-Sub-PAS. We propose that the increased effectiveness of AP-Sub-PAS over PA-Sub-PAS is due to the fact that AP TMS more readily activates I3 inputs to corticospinal neurons and hence that these are an important component of associative plasticity in the human motor cortex.
Sex-specific QTLs and interacting loci underlie salt-sensitive hypertension and target organ complications in Dahl S/jrHS hypertensive rats
Authors: Herrera Victoria L. M. , Tsikoudakis Aristides , Ponce Lorenz R. B. , Matsubara Yuichi , Ruiz-Opazo Nelson
Published: May 2006

Sex-specific differences in polygenic (essential) hypertension are commonly attributed to the role of sex steroid hormone-receptor systems attenuating sex-common disease mechanisms in premenopausal women. However, emerging observations indicate sex-specific genetic susceptibility in various traits, thus requiring systematic study. Here we report a comparative analysis of independent total genome scans for salt-sensitive hypertension susceptibility quantitative trait loci (QTLs) in male and female F2 [Dahl R/jrHS × S/jrHS] intercross rats exposed to high-salt (8% NaCl) rat diets. Hypertension was phenotyped with three quantitative traits: blood pressure (BP) elevation associated with increased hypertensive renal disease [glomerular injury score (GIS)] and increased cardiac mass [relative heart weight (RHW)] obtained 8–12 wk after high-salt challenge; 24-h nonstress, telemetric BP measurements were used. Although sex-common QTLs were detected for BP [chromosome (chr) 1–144.3 Mbp; chr 1–208.8 Mbp], GIS (chr 1–208.8 Mbp), and cardiac mass (chr 5–150.3 Mbp), most QTLs across the three phenotypes studied are gender specific as follows: female QTLs for BP (chr 2–106.7 Mbp, chr 2–181.7 Mbp, chr 5–113.9 Mbp, chr 5–146.7 Mbp, chr 12–12.8 Mbp), GIS (chr 15–59.6 Mbp), and RHW (chr 2–31.5 Mbp, chr 5–154.7 Mbp, chr 5–110.9 Mbp); male QTLs for BP (chr 2–196.7 Mbp, chr 11–48.0 Mbp, chr 20–35.7 Mbp), GIS (chr 6–3.3 Mbp, chr 20–40.7 Mbp), and RHW (chr 6–3.3 Mbp, chr 20–40.7 Mbp). Furthermore, interacting loci with significant linkage were detected only in female F2 intercross rats for BP and hypertensive renal disease. Comparative analyses revealed concordance of BP QTL peaks with previously reported rat model and human hypertension susceptibility genes and with BP QTLs in previous Dahl S-derived F2 intercross studies and also suggest strain-specific genetic modifiers of sex-specific determinants. Altogether, the data provide key experimental bases for sex-specific investigation of mechanisms and intervention and prevention strategies for polygenic hypertension in humans.
N-ethyl-N-nitrosourea-based generation of mouse models for mutant G protein-coupled receptors
Authors: Grosse Johannes , Tarnow Patrick , Römpler Holger , Schneider Boris , Sedlmeier Reinhard , Huffstadt Ulrike , Korthaus Dirk , Nehls Michael , Wattler Sigrid , Schöneberg Torsten , Biebermann Heike , Augustin Martin
Published: May 2006

Chemical random mutagenesis techniques with the germ line supermutagen N-ethyl- N-nitrosourea (ENU) have been established to provide comprehensive collections of mouse models, which were then mined and analyzed in phenotype-driven studies. Here, we applied ENU mutagenesis in a high-throughput fashion for a gene-driven identification of new mutations. Selected members of the large superfamily of G protein-coupled receptors (GPCR), melanocortin type 3 (Mc3r) and type 4 (Mc4r) receptors, and the orphan chemoattractant receptor GPR33, were used as model targets to prove the feasibility of this approach. Parallel archives of DNA and sperm from mice mutagenized with ENU were screened for mutations in these GPCR, and in vitro assays served as a preselection step before in vitro fertilization was performed to generate the appropriate mouse model. For example, mouse models for inherited obesity were established by selecting fully or partially inactivating mutations in Mc4r. Our technology described herein has the potential to provide mouse models for a GPCR dysfunction of choice within <4 mo and can be extended to other gene classes of interest.
Dissecting Stages of Mesenchymal-to-Epithelial Conversion during Kidney Development
Authors: Schmidt-Ott Kai M. , Lan Debin , Hirsh Benjamin J. , Barasch Jonathan
Published: May 2006

During embryonic development, the structures of the nephron from the glomerulus to distal tubule derive from the metanephric mesenchyme. The mesenchymal cells change their cell type and produce highly organized epithelia under the influence of signals from the ureteric bud. The morphological sequence of this conversion includes the formation of a corona of mesenchymal cells surrounding the tips of the ureteric bud, followed by the development of a pre-tubular aggregate, which evolves into preliminary forms of the segmented nephron. Currently, these stages are largely based on histomorphologic criteria and expression of marker molecules. However, to dissect the effects of inductive signals from the ureteric bud in more detail, a sophisticated readout of stages in the conversion process is required, based on the onset of epithelial polarity and the occurrence of vectorial transport. In this review, we discuss some of the new approaches in establishing the staging of the conversion process.
Impact of Early Tirofiban Administration on Myocardial Salvage in Patients with Acute Myocardial Infarction Undergoing Infarct-Related Artery Stenting
Authors: Emre Ayse , Ucer Ekrem , Yesilcimen Kemal , Bilsel Tuba , Oz Dilaver , Sayar Nurten , Terzi Sait , Akbulut Tamer , Ersek Birsen
Published: May 2006

Background/Aims: The timing of GpIIb/IIIa inhibitor administration may be important in achieving early epicardial and myocardial reperfusion. We evaluated the effect of early tirofiban on myocardial salvage and cardiovascular outcome in patients with acute myocardial infarction (AMI) undergoing infarct-related artery stenting. Methods: Patients (n = 66) with a first AMI presenting <6 h from onset of symptoms were randomized to either early administration of tirofiban in the emergency room (n = 32) or later administration in the catheterization laboratory (n = 34) (tirofiban bolus dose of 10 µg/kg, followed by 0.15 µg/kg for 24 h). The primary end-point was the degree of myocardial salvage, determined by means of serial scintigraphic studies with technetium-99m sestamibi. Thirty-day major adverse cardiac events were also assessed. Results: There were no significant differences in patient characteristics or in their presentation. The mean door-to-balloon time was similar in both groups (43 ± 12 and 53 ± 9 min, p = 0.08). The early and late treatment groups received tirofiban 18 ± 4 and 52 ± 10 min after admission, respectively. Angiographic analysis revealed a higher initial frequency of TIMI grade 3 flow in the early group (31% vs. 12%, p = 0.04). Procedural success was achieved in all patients. Myocardial risk area were comparable between early and late treatment groups (35.6 ± 12.2% vs. 39.3 ± 14.0%, p = 0.6). Scintigraphic outcomes demonstrated a significant reduction in the final infarction size (11.8 ± 5.2% vs. 22.4 ± 6.2%, p = 0.01), and improvement in salvage index (0.68 ± 0.22 vs. 0.44 ± 0.18, p = 0.003) in favor of the early tirofiban group. The thirty-day composite end-point of death, recurrent MI or rehospitalization also favored the early group (6% early, 15% late, p = 0.06). Conclusion: Early tirofiban administration enhanced the degree of myocardial salvage and clinical outcome in patients with AMI undergoing infarct-related artery stenting.
Effects of Itopride Hydrochloride on Plasma Gut-Regulatory Peptide and Stress-Related Hormone Levels in Healthy Human Subjects
Authors: Katagiri Fumihiko , Shiga Toru , Inoue Shin , Sato Yuhki , Itoh Hiroki , Takeyama Masaharu
Published: May 2006

Itopride hydrochloride (itopride), a gastrokinetic drug, has recently been evaluated for its clinical usefulness in functional dyspepsia. We investigated effects of itopride on human plasma gastrin-, somatostatin-, motilin-, and cholecystokinin (CCK)-like immunoreactive substances (IS); adrenocorticotropic hormone (ACTH)-immunoreactive substances (IS), and cortisol under stress conditions in healthy subjects. A single administration of itopride caused significant increases in plasma somatostatin- and motilin-IS levels compared to placebo. Itopride significantly decreased plasma CCK-IS, and suppressed the ACTH-IS level compared to placebo. We hypothesize that itopride may have an accelerating gastric emptying effect, and a modulatory effect on the hypothalamo-pituitary-adrenal axis and autonomic nervous functions. These effects might be beneficial in stress-related diseases, suggesting that itopride has clinicopharmacological activities.
Investigating the Enhancing Effect of Music on Autobiographical Memory in Mild Alzheimer’s Disease
Authors: Irish Muireann , Cunningham Conal J. , Walsh J. Bernard , Coakley Davis , Lawlor Brian A. , Robertson Ian H. , Coen Robert F.
Published: May 2006

The enhancing effect of music on autobiographical memory recall in mild Alzheimer’s disease individuals (n = 10; Mini-Mental State Examination score >17/30) and healthy elderly matched individuals (n = 10; Mini-Mental State Examination score 25–30) was investigated. Using a repeated-measures design, each participant was seen on two occasions: once in music condition (Vivaldi’s ‘Spring’ movement from ‘The Four Seasons’) and once in silence condition, with order counterbalanced. Considerable improvement was found for Alzheimer individuals’ recall on the Autobiographical Memory Interview in the music condition, with an interaction for condition by group (p < 0.005). There were no differences in terms of overall arousal using galvanic skin response recordings or attentional errors during the Sustained Attention to Response Task. A significant reduction in state anxiety was found on the State Trait Anxiety Inventory in the music condition (p < 0.001), suggesting anxiety reduction as a potential mechanism underlying the enhancing effect of music on autobiographical memory recall.
Effects of Midazolam and Morphine on Cerebral Oxygenation and Hemodynamics in Ventilated Premature Infants
Authors: van Alfen-van der Velden A.A.E.M. , Hopman J.C.W. , Klaessens J.H.G.M. , Feuth T. , Sengers R.C.A. , Liem K.D.
Published: May 2006

Background: Midazolam sedation and morphine analgesia are commonly used in ventilated premature infants. Objectives: To evaluate the effects of midazolam versus morphine infusion on cerebral oxygenation and hemodynamics in ventilated premature infants. Methods: 11 patients (GA 26.6–33.0 weeks, BW 780–2,335 g) were sedated with midazolam (loading dose 0.2 mg/kg, maintenance 0.2 mg/kg/h) and 10 patients (GA 26.4–33.3 weeks, BW 842–1,955 g) were sedated with morphine (loading dose 0.05 mg/kg, maintenance 0.01 mg/kg/h). Changes in oxyhemoglobin (ΔcO2Hb) and deoxyhemoglobin (ΔcHHb) were assessed using near infrared spectrophotometry. Changes in cHbD (= ΔcO2Hb – ΔcHHb) reflect changes in cerebral blood oxygenation and changes in concentration of total hemoglobin (ΔctHb = ΔcO2Hb + ΔcHHb) represent changes in cerebral blood volume (ΔCBV). Changes in cerebral blood flow velocity (ΔCBFV) were intermittently measured using Doppler ultrasound. Heart rate (HR), mean arterial blood pressure (MABP), arterial oxygen saturation (saO2) and transcutaneous measured pO2 (tcpO2) and pCO2 (tcpCO2) were continuously registered. Statistical analyses were carried out using linear mixed models to account for the longitudinal character study design. Results: Within 15 min after the loading dose of midazolam, a decrease in saO2, tcpO2 and cHbD was observed in 5/11 infants. In addition, a fall in MABP and CBFV was observed 15 min after midazolam administration. Immediately after morphine infusion a decrease in saO2, tcpO2 and cHbD was observed in 6/10 infants. Furthermore, morphine infusion resulted in a persistent increase in CBV. Conclusions: Administration of midazolam and morphine in ventilated premature infants causes significant changes in cerebral oxygenation and hemodynamics, which might be harmful.
Advantage of the Right Lateral Position Compared with the Lithotomy Position during the Perineal Procedure in Abdominoperineal Resection
Authors: Iwamura Takeshi , Hotokezaka Masayuki , Eto Tada-aki , Taniguchi Tomotaka , Chijiiwa Kazuo
Published: May 2006

Background/Aims: Abdominoperineal resection (APR) is generally performed in the lithotomy position (LT-APR). The aim of this retrospective study was to evaluate the advantage of the right lateral (RL) position during the perineal phase of APR, in extended APR (ext-APR) that needed additional excision of the pelvic organs and sacrococcyx, and in total pelvic exenteration (TPE). Methods: The present study is based on 50 patients observed from January 1993 to December 2004 (43 with primary rectal malignancy, 7 with recurrent cancer), who had undergone the following surgeries: LT-APR was carried out in 20 patients, RL-APR in 13, LT-ext-APR in 5, RL-ext-APR in 8, LT-TPE in 2 and RL-TPE in 2. Perioperative factors were compared between the LT and RL position in each operative procedure. Results: When RL-APR was compared with LT-APR, operative time (including the time to change the position) and the amount of operative blood loss were significantly less in RL-APR (mean ± SE = 314 ± 16 vs. 381 ± 18 min, p = 0.0156 and 598 ± 78 vs. 1,160 ± 171 g, p = 0.0168, respectively). The blood loss and operative time were also significantly less in RL-ext-APR than in LT-ext-APR (1,060 ± 170 vs. 3,590 ± 1,270 g, p = 0.0277 and 353 ± 31 vs. 488 ± 41 min, p = 0.0219, respectively). The average blood loss and operative time were 4,190 g and 650 min in LT-TPE, and 1,450 g and 609 min in RL-TPE, respectively. Conclusion: The RL position during the perineal phase following the abdominal phase in the LT position significantly decreases blood loss and operative time in APR and ext-APR.
Compartimentalization for Chylothorax Originating from the Abdomen after Extended Esophagectomy
Authors: Omloo J.M.T. , Lagarde S.M. , Vrouenraets B.C. , Busch O.R.C. , van Lanschot J.J.B.
Published: May 2006

Background: Chyle leakage from the chest after extended esophagectomy originating from the abdomen is a rare complication with various clinical presentations and treatments. Methods: Two cases of chylothorax originating from the abdomen are discussed and the literature concerning diagnosis, management and outcome is reviewed. Results and Conclusion: Initially conservative measures should be installed; however, prolonged conservative treatment should be avoided. Reoperation gives an opportunity to identify the leak. If the leakage originates from the abdomen, compartimentalization is the essential step to solve the problem.
Role of NO and Prostaglandins in Acute Hypoxic Vasoconstriction in Sheep Pulmonary Veins
Authors: Uzun Özge , Demiryürek Abdullah T.
Published: May 2006

The aim of this study was to investigate the effect of hypoxia on and the role of nitric oxide (NO) and cyclooxgenase inhibition in hypoxia-induced vasoconstriction in sheep isolated pulmonary veins. We used the potent pulmonary vasoconstrictor U46619, a thromboxane analog, as a precontractile agent. Our results showed that hypoxia caused a vasoconstriction both under resting tone and in U46619 (10–6 mol/l) precontracted pulmonary veins. In the presence of the nonselective NO synthase inhibitior Nω-nitro-L-arginine methyl ester (L-NAME; 3 × 10–5 mol/l), the hypoxic pulmonary vasoconstriction (HPV) was significantly increased in veins under resting force. However, there was a decrease in HPV in pulmonary veins precontracted with U46619 in the presence of L-NAME. Moreover, L-NAME markedly augmented the U46619-induced pulmonary contractions under normoxic conditions. Cyclooxygenase inhibition with indomethacin (10–5 mol/l) significantly reduced the HPV both under resting tone and in precontracted veins. Indomethacin also significantly decreased the U46619-induced pulmonary contractions prior to the induction of hypoxia. Our findings suggest that NO and prostaglandins can act as a modulators of the hypoxic vasoconstriction in isolated pulmonary veins.
Narcissistic Regulation of the Self and Interpersonal Problems in Depersonalized Patients
Authors: Michal M. , Kaufhold J. , Overbeck G. , Grabhorn R.
Published: May 2006

Background: Psychoanalytical theories coincide in understanding depersonalization (DP) as a disorder of narcissistic self-regulation. DP is described as an ego defense against overwhelming shame resulting in a splitting of an observing ego detached from the experiencing self. In contrast to a behavioral-cognitive theory on DP, which suggests that the catastrophic appraisal of normal transient DP maintains the disorder, psychodynamic approaches stress that DP is an important defensive function for the individual. We examine this psychodynamic aspect more closely as it relates to narcissistic self-regulation and interpersonal behavior in depersonalized patients. Sampling and Methods: Thirty-five patients with pathological DP are compared with 28 patient controls concerning their narcissistic self-regulation and interpersonal behavior. For the assessment, we used the German Narcissism Inventory and the Inventory of Interpersonal Problems. The two groups were controlled for sociodemographic data, comorbidity with a personality disorder, and the General Severity Index of the Symptom Check List-90-R. Results: Bonferroni-corrected group comparison showed that the depersonalized patients are characterized by perceiving themselves as helpless, hopeless, socially isolated and worthless, perceiving others as bad and disappointing, and that they avoid interpersonal relations and reality significantly more than other patients with equal symptom severity. Conclusions: Treatment approaches on DP should take the issue of low self-esteem, pervasive shame and the related defensive social avoidance into account. Further empirical research on psychodynamic concepts of DP is warranted also for the sake of linking modern neurobiological findings with clinical experience.
Comparative Morphology of the Avian Cerebellum: I. Degree of Foliation
Authors: Iwaniuk Andrew N. , Hurd Peter L. , Wylie Douglas R.W.
Published: May 2006

Despite the conservative circuitry of the cerebellum, there is considerable variation in the shape of the cerebellum among vertebrates. One aspect of cerebellar morphology that is of particular interest is the degree of folding, or foliation, of the cerebellum and its functional significance. Here, we present the first comprehensive analysis of variation in cerebellar foliation in birds with the aim of determining the effects that allometry, phylogeny and development have on species differences in the degree of cerebellar foliation. Using both conventional and phylogenetically based statistics, we assess the effects of these variables on cerebellar foliation among 91 species of birds. Overall, our results indicate that allometry exerts the strongest effect and accounts for more than half of the interspecific variation in cerebellar foliation. In addition, we detected a significant phylogenetic effect. A comparison among orders revealed that several groups, corvids, parrots and seabirds, have significantly more foliated cerebella than other groups, after accounting for allometric effects. Lastly, developmental mode was weakly correlated with relative cerebellar foliation, but incubation period and fledging age were not. From our analyses, we conclude that allometric and phylogenetic effects exert the strongest effects and developmental mode a weak effect on avian cerebellar foliation. The phylogenetic distribution of highly foliated cerebella also suggests that cognitive and/or behavioral differences play a role in the evolution of the cerebellum.
Association between Alcohol Intake and Domain-Specific Cognitive Function in Older Women
Authors: Espeland Mark A. , Coker Laura H. , Wallace Robert , Rapp Stephen R. , Resnick Susan M. , Limacher Marian , Powell Lynda H. , Messina Catherine R.
Published: May 2006

Moderate levels of alcohol intake may be associated with better cognitive function; however, this relationship may vary between cognitive domains. Women, aged 65–80 years, enrolled in the Women’s Health Initiative (WHI) randomized clinical trials of hormone therapy, underwent annual standardized testing for global cognitive function through the ancillary WHI Memory Study (average follow-up of 4.5 years) and domain-specific cognitive function through the WHI Study of Cognitive Aging (average follow-up of 1.7 years). Compared to nondrinkers, women reporting moderate levels of alcohol intake (≤3 drinks per day) performed better on a measure of global cognitive function. Women reporting any alcohol intake also performed better on tests of verbal knowledge, verbal fluency, figural memory, verbal memory, attention and working memory, and motor speed (all p < 0.05), but not spatial ability (p = 0.36). After covariate adjustment, mean scores were higher among women reporting ≧1 drink/day by 5.7% for verbal knowledge (p < 0.001) and by 5.7% for phonemic fluency (p = 0.004), compared to never-drinkers. Moderate levels of alcohol intake are associated with somewhat better cognition, which may be expressed most strongly in functions related to verbal knowledge and phonemic fluency. However, our observational study cannot rule out confounding associations with unmeasured factors.
Prevalence and Risk Factors of HPV Infection among High-Risk Rural and Urban Lithuanian Women
Authors: Kliucinskas Mindaugas , Nadisauskiene Ruta J. , Minkauskiene Meile
Published: May 2006

Aims: To investigate the prevalence, persistence and risk factors of high oncogenic risk human papillomavirus (HPV) among urban and rural women of reproductive age coming to consult a gynaecologist. Methods: A prospective cohort study in urban (Kaunas) and rural (Marijampole) regions of Lithuania. The data were collected in 8 healthcare institutions from women seeking consultation of gynaecologists using a questionnaire for finding out demographic, social, behavioural and biomedical factors. HPV DNA was determined by molecular hybridization method (hybrid capture version II) determining HPV of high oncogenic risk. Result: 1,120 women participated in the study. The prevalence of high-risk HPV among the studied women was 25.1%. It was higher among the urban women than among the rural women. The prevalence of high-risk HPV was increased if the subjects had 2 or more sexual partners during the last 12 months (OR 2.81; 95% CI 1.83–4.32), were 19 years of age or younger (OR 2.68; 95% CI 1.47–4.91), were smoking (OR 1.81; 95% CI 1.16–2.81), and had secondary or lower education level (OR 1.43; 95% CI 1.01–2.04). This infection was obviously associated with high- and low-grade squamous intraepithelial changes of the cervix (OR 1.66, 95% CI = 1.08–2.53). Conclusion: The incidence rate for cervical cancer in Lithuania is one of the highest in comparison with other European countries. HPV infection was also particularly common in the studied population. About one-fourth of the women were infected with high-risk HPV infection. Young and less educated women were found to be the group that was most exposed to HPV, and therefore public health interventions and education seem to be essential in programs aimed at reducing the incidence of cervical cancer.