bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance, plasticity, and acclimation of the nonindigenous shrub Lonicera maackii (Caprifoliaceae) in contrasting light environments
Authors: Luken J. O. , Tholemeier T. C. , Kuddes L. M. , Kunkel B. A.
Published: April 2008

Growth and photosynthetic capability of the eastern Asiatic shrub Lonicera maackii (Rupr.) Herder were measured in shadehouses and in artificial canopy gaps. In shadehouses providing 5, 25, and 100% of full sun, total dry mass, and leaf area of seedlings increased with light availability; specific leaf area and leaf area ratio decreased with light availability. When small suppressed shrubs were transplanted from a forest site to the shadehouse environments, rapid (13 day) acclimation in existing leaves initially produced the highest mean photosynthetic rate (8.12 μmol∙m−2∙s−1) and the highest mean relative stem growth at 25% light. However, maximum mean photosynthetic rate (10.36 μmol∙m−2∙s−1), higher mean stomatal density, and increased mean leaf thickness were measured only in new leaves formed in 100% light. This plastic response was associated with higher relative stem growth later in the experiment. Naturally established seedlings in both artificial canopy gaps and sites with intact canopies had low and negative relative stem growth, presumably as a result of light limitation. The results support the observation that L. maackii is a shade intolerant species that performs best in forests where large disturbances or edge effects create enhanced light availability. Key words: acclimation, forest edge, invasive species, Lonicera maackii, plasticity, shade tolerance.
Ceratorhiza pernacatena and Epulorhiza calendulina spp.nov.: mycorrhizal fungi of terrestrial orchids
Authors: Zelmer Carla D. , Currah R. S.
Published: April 2008

Two new species of fungi mycorrhizal with terrestrial orchids native to the Canadian prairies are described and illustrated. Ceratorhiza pernacatena sp.nov., from mycorrhizas of Platanthera praeclara, produces globose monilioid cells linked by narrow, tubular, connections that contain the septum between adjacent cells. Hyphae are binucleate, 5–7 μm in width, regularly septate with perforate parenthesomes. Cellulase is produced, but polyphenol oxidase production is low to absent. Epulorhiza calendulina sp.nov., from mycorrhizas of Amerorchis rotundifolia, is distinguished from other Epulorhiza species by the orange to ochre colour of colonies on potato dextrose agar. On corn meal agar, clavate to irregular monilioid cells are produced in short, branched, chains arising from lateral hyphal branches. Runner hyphae are binucleate, 3.0–4.7 μm in width, regularly septate, with flattened, imperforate parenthesomes. Polyphenol oxidase production is lacking, but cellulase is produced. Key words: orchid mycorrhizas, Amerorchis rotundifolia, Platanthera praeclara, Rhizoctonia.
Within and among flower sex-phase distribution in Alstroemeria aurea (Alstroemeriaceae)
Authors: Aizen Marcelo A. , Basilio Alicia
Published: April 2008

Although dichogamy is a prevailing feature of the angiosperms, the simultaneous change from male to female phases among hermaphrodite flowers within a plant (i.e., synchronous protandry) has been reported for only a few families (e.g., Araliaceae, Umbelliferae). Here we present an example of synchronous protandry at the ramet level in the Alstroemeriaceae. Dichogamy was analyzed in clonal Alstroemeria aurea at the flower, ramet, and at the whole flowering patch level. Alstroemeria aurea is self-compatible but totally dependent on biotic agents for pollen transfer. There was evidence of strong inbreeding depression expressed during seed development. Comparisons of seed set in open-pollinated flowers with those obtained after hand selfing and outcrossing resulted in a selfing rate of 0.3. At the flower level protandry was complete. The male phase lasted about 4 days and the female phase lasted about 3 days. Between the female and male phase, there was an approximately 1-day long "neuter" phase. Flowering ramets produce a terminal inflorescence bearing one or more whorls of flowers. Within a ramet, flowers of the same order opened within a period of 1–2 days, and male and female phases of different flowers did not overlap. When inflorescences held two whorls of flowers, the ramet went through two alternating non-overlapping male–female cycles. Using spatial autocorrelation techniques, we found little evidence for pairs of neighboring ramets expressing the same sexual phase beyond random expectations at any scale ranging between 0.25 to 15 m. By ensuring pollen interchange between flowering ramets, synchronized protandry at the ramet level could be an important feature in reducing selfing in A. aurea. Key words: Alstroemeria aurea, dichogamy, synchronous protandry, inbreeding depression.
Ubiquinol–cytochrome-c reductase 7.2 kDa protein of mitochondrial complex III is steroid-responsive and increases in cardiac hypertrophy and hypertension
Authors: Huynh Hung , Servant Nicolas , Chalifour Lorraine E.
Published: April 2008

Women and men do not respond identically to cardiac insults; premenopausal women are somewhat protected from cardiovascular disease. Our objective was to isolate and characterize hormone-responsive genes in the heart. Differential display identified an estrogen-inducible fragment that was found to encode the ubiquinol–cytochrome-c reductase (UCCR) 7.2 kDa protein of the mitochondrial respiratory complex III. We found UCCR7.2 mRNA to be highly expressed in the heart, and this expression increased in hearts of 4-, 10-, and 28-week-old spontaneously hypertensive rats (SHR) compared with normotensive Wistar–Kyoto rats. Oral hydralazine treatment to reduce hypertension reduced SHR UCCR7.2 expression. Cardiac UCCR7.2 mRNA expression was also increased significantly after a 5/6 nephrectomy compared with mock surgery. Cardiac expression after ovariectomy was 50% that of intact rats. Supplementation of ovariectomized rats with estrogen had no effect, whereas progesterone increased cardiac expression, although not to intact levels. No change in cardiac UCCR7.2 expression was found when intact rats were treated with either tamoxifen or ICI 182780. Thus, UCCR7.2 expression is reduced in the absence of ovarian hormones, but is not directly regulated by estrogen in the heart. We conclude that UCCR7.2 is a steroid hormone-responsive gene in the heart, with expression increased in cardiac hypertrophy and in response to hypertension.
Interrelationship of antioxidative status, lipid peroxidation, and lipid profile in insulin-dependent and non-insulin-dependent diabetic patients
Authors: Cimbaljević Branko , Vasilijević Ana , Cimbaljević Slavica , Buzadžić Biljana , Korać Aleksandra , Petrović Vesna , Janković Aleksandra , Korać Bato
Published: April 2008

This study aimed to investigate the interrelationship of plasma lipid profile, lipid peroxidation, and erythrocyte antioxidative defense in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. Plasma levels of total cholesterol, triglycerides, and lipid peroxides and the activities of copper, zinc superoxide dismutase (CuZnSOD), catalase, glutathione peroxidase (GSH-Px), as well as the amount of glutathione in erythrocytes, were determined in IDDM, NIDDM, and nondiabetic control subjects. Additionally, morphology of erythrocytes in all subjects was examined. Plasma levels of total cholesterol and triglycerides were significantly increased in NIDDM compared with controls. Also, the lipid peroxide level was higher in NIDDM than in either control or IDDM subjects. CuZnSOD activity in erythrocytes was elevated in NIDDM patients compared with the control. In NIDDM patients, more extensive erythrocyte spherocytosis and echinocytosis compared with both control and IDDM subjects were observed. In contrast with the IDDM group, the observed abnormality in lipid metabolism in NIDDM patients is closely associated with increased lipid peroxidation, changes in antioxidative defense, and erythrocyte morphology.
Cholesterol-induced stimulation of platelet aggregation is prevented by a hempseed-enriched dietThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.
Authors: Prociuk M.A. , Edel A.L. , Richard M.N. , Gavel N.T. , Ander B.P. , Dupasquier C.M.C. , Pierce G.N.
Published: April 2008

Hypercholesterolemia indirectly increases the risk for myocardial infarction by enhancing the ability of platelets to aggregate. Diets enriched with polyunsaturated fatty acids (PUFAs) have been shown to reduce the detrimental effects of cholesterol on platelet aggregation. This study investigated whether dietary hempseed, a rich source of PUFAs, inhibits platelet aggregation under normal and hypercholesterolemic conditions. Male New Zealand white rabbits were fed one of 6 dietary interventions: regular control diet (RG); control diet + 10% hempseed (HP); control diet + 10% partially delipidated hempseed (DHP); control diet + 0.5% cholesterol (OL); control diet + 0.5% cholesterol + 10% hempseed (OLHP); control diet + 5% coconut oil (CO). After 8 weeks, blood was collected to measure ADP- and collagen-induced platelet aggregation and plasma levels of fatty acids, cholesterol, and triglycerides. The hempseed-fed animals (HP and OLHP) displayed elevated plasma levels of PUFAs and a prominent enhancement in 18:3n-6 (γ-linolenic acid, GLA) levels, a unique PUFA found in hempseed. The cholesterol-supplemented groups (OL and OLHP) had significantly elevated plasma levels of cholesterol and triglycerides, but platelet aggregation was significantly augmented only in the OL group. The addition of hempseed to this diet (OLHP) normalized aggregation. The direct addition of GLA to the OL platelet samples blocked the cholesterol-induced stimulation of platelet aggregation. The results of this study demonstrate that when hempseed is added to a cholesterol-enriched diet, cholesterol-induced platelet aggregation returns to control levels. This normalization is not due to a reduction in plasma cholesterol levels, but may be partly due to increased levels of plasma GLA.
Properties of thiamin transport in isolated perfused hearts of chronically alcoholic guinea pigsThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.
Authors: Petrovic Milos M. , Scepanovic Ljiljana , Rosic Gvozden , Mitrovic Dusan M.
Published: April 2008

The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of healthy (nonalcoholic) and chronically alcoholic guinea pigs. We used the single-pass, paired-tracer dilution method on isolated and retrogradely perfused guinea pig hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 14C-thiamin were determined under control conditions and under influence of possible modifiers. We tested how the presence of unlabeled thiamin, metabolic inhibitors, or absence of sodium ions influence the transport of 14C-thiamin. The results of our experiments show that the transport of 14C-thiamin is specific and energy-dependent and that its properties are significantly changed under the influence of chronic alcoholism. The latter effect occurs by increase in both Umax and Utot, as a manifestation of a compensatory mechanism in thiamin deficiency.
Lipid and lipoprotein profile in women with polycystic ovary syndromeThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.
Authors: Macut Djuro , Panidis Dimitrios , Glišić Biljana , Spanos Nikolaos , Petakov Milan , Bjekić Jelica , Stanojlović Olivera , Rousso David , Kourtis Anargyros , Božić Ivana , Damjanović Svetozar
Published: April 2008

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by obesity-related risk factors for cardiovascular disease. The objective of our study was to determine values of key lipid and lipoprotein fractions in PCOS, and their possible relation to insulin resistance. A total of 75 women with PCOS (aged 23.1 ± 5.1 years, BMI 24.9 ± 4.7 kg/m2), and 56 age- and BMI-matched controls were investigated. In all subjects, basal glucose, cholesterol (total, HDL, and LDL), oxidized LDL (OxLDL), triglycerides, apolipoprotein (apo)A1, apoB, and apoE, nonesterified fatty acids, insulin, testosterone, sex hormone-binding globulin, homeostasis model assessment (HOMA) index, and free androgen index were determined in the follicular phase of the cycle. PCOS patients compared with controls had increased indices of insulin resistance, basal insulin (p < 0.001), and HOMA index (p < 0.001), and worsened insulin resistance-related dyslipidemia with decreased HDL cholesterol (p < 0.01), elevated triglycerides (p = 0.010), and pronounced LDL oxidation (p < 0.001). In conclusion, characteristic dyslipidemia of insulin resistance and unfavorable proatherogenic lipoprotein ratios were present only in women with PCOS and not in controls. Elevated OxLDL and the relation of apoE and nonesterified fatty acids with insulin resistance suggest that women with PCOS are at increased risk for premature atherosclerosis.
Proapoptotic and antiapoptotic effects of hyperglycemia: role of insulin signalingThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.
Authors: Ricci Craig , Jong Chian Ju , Schaffer Stephen W.
Published: April 2008

Glucose toxicity is an important initiator of cardiovascular disease, contributing to the development of insulin resistance, impaired contractile function, abnormal energy metabolism, cardiomyocyte and endothelial cell death, coronary heart disease, and heart failure. High blood glucose can, however, paradoxically protect the heart against a variety of insults, including ischemia, hypoxia, and calcium overload. To provide information on the underlying basis of these divergent actions of high glucose, the present study examined the hypothesis that the adverse effects of high glucose are linked to impaired insulin signaling, leading to a reduction in the levels of cytoprotective factors, and that the beneficial effects of high glucose occur in the absence of insulin and result in an improvement in Akt signaling. This hypothesis was evaluated by using an in vitro cardiomyocyte model that is amenable to manipulations in glucose and insulin. Prolonged exposure of the isolated neonatal cardiomyocyte to medium containing insulin and high glucose led to increased susceptibility to angiotensin II-mediated apoptosis, an effect associated with reduced levels of phospho-Akt and an increased Bax/Bcl-2 ratio. By contrast, exposure to high glucose levels in the absence of insulin rendered the cardiomyocyte resistant to angiotensin II-mediated apoptosis. Because the beneficial effects of high glucose were associated with elevations in phospho-Akt and Bcl-2 content, the cardioprotective activity of high glucose resembles the actions of insulin. Hence, the activation state of Akt is largely determined by the activity of insulin and other growth factors. Because high glucose diminishes insulin signaling, it reduces phospho-Akt levels and renders the cell susceptible to damaging insults. In the absence of insulin, however, the natural activity of high glucose is unmasked. As a result, Akt signaling is increased and the cell is rendered resistant to cell death.
MULTIPOLE MATRIX ELEMENTS 〈nl|rβ|El'〉v FOR H-LIKE ATOMS AND THEIR APPLICATIONS (AS β = 1, n ≤ 4, Enl < 0 ≤ E ≤ 1)
Authors: TARASOV V. F.
Published: April 2008

This article deals with the connection between multipole matrix elements 〈nl|rβ|n'l'〉ν and 〈nl|rβ|El'〉ν for H-like atoms, where ν is the so-called "auxiliary" parameter of Heun's differential equation and [Formula: see text] is the "effective" nuclear charge, and new properties of Appell's function F2(x,y) to the vicinity of the singular point (1, 1) and in addition, here, first V. A. Fock's idea for the continuous spectrum is taken into consideration. Such an approach allows us to get the explicit expressions for squares of the dipole moments and the certain physical characteristics in atomic physics and also their exact numerical values, e.g., the average oscillator strengths [Formula: see text] and the line intensities J(nl, El'), etc., as n ≤ 4, l'= l ± 1 and 0 ≤ E ≤ 1 (see Tables 1–3). Besides, diagrams of certain radial functions for the discrete-continuous transitions are given here.
A NEW DYNAMICAL FRICTION MODEL
Authors: GUO KEJIAN , ZHANG XINGANG , LI HONGGUANG , HUA HONGXING , MENG GUANG
Published: April 2008

This paper proposed a new dynamical friction model structure which allows accurate modeling both in sliding and presliding regimes. Transition between these two regimes is accomplished without a switching function. In the presliding regime, the model has the characters of a Bouc–Wen model, so it can adapt to various hysteretic behaviors. While in the gross-sliding regime, the model is equivalent to a general velocity-dependent friction model. Therefore, the dynamical characters of friction force in this regime, such as negative friction-velocity slope, can be described also. Furthermore, the transition between these two regimes is not abrupt, but smooth, and needs no extra function. The application of this model is demonstrated by describing experimentally obtained friction force for a guide–rail system. Numerical simulation results for a vibration system with friction show the practicability of the model to predict dynamic characteristics such as hysteretic behavior in presliding, velocity-dependent behavior in sliding, and stick-slip behavior.
TRANSITIONS BETWEEN WANNIER–STARK STATES OF SEMICONDUCTOR SUPERLATTICES UNDER ELECTROSTATIC FIELD
Authors: HAN WEI , YAN DADONG , CHEN ZHANGJIAN
Published: April 2008

We investigate the transitions between two minibands in a semiconductor superlattice under the influence of high static electric fields. Our numerical calculation, which is based on the two energy levels system, shows that this interminiband transition will lead to anticrossings that can be determined by the coupled Hamiltonian. In the time domain, spatial oscillations come forth between the main locations of the particle in the two transition states. At the anticrossings, the amplitudes are the maximum which agree with the experimental results.
NOISE-INDUCED SYNCHRONIZATION IN LORENZ OSCILLATORS
Authors: YANG JUNZHONG , ZHANG MEI
Published: April 2008

We investigate noise-induced synchronization in Lorenz systems. We find that common noise can induce synchronization even if its impact on the system is confined to a small region in the Lorenz phase space. The mechanism is revealed to be related to changes in the distribution of the attractor in the phase space.
TRANSIENT FREE CONVECTION DEVELOPMENT IN HOT-WIRE EXPERIMENTS
Authors: GIARETTO VALTER
Published: April 2008

The transient behavior of free convection along the vertical wire of a hot-wire apparatus has been experimentally investigated at room temperature and ambient pressure, using water and propylene glycol. The development of free convection has been studied using an ad hoc apparatus, in order to obtain the best agreement between the vertical direction and the wire. The measurements were corrected for radiation influences, and the effects induced by free convection were detected at the wire-fluid interface.

The convection outcomes have been correlated to fluid properties and test conditions. A suitable time scale has been introduced, which is defined by the modified Fourier and a proper definition of the local Grashof number. The obtained correlation has been applied to data found in the literature. The possibility of describing the free convection development at the wire-fluid interface could enable the fluid properties related to momentum diffusion to be investigated by the hot-wire technique.
THE CONSISTENCY OF THE ADIABATIC AND EXACT GEOMETRIC PHASES
Authors: JIA XINYAN , LI WEIDONG , LIANG J.-Q.
Published: April 2008

With the help of the time-dependent gauge transformation, by which a set of time-invariant eigenstates of the Hamiltonian can be obtained, the geometric phase of the time-dependent system is obtained analytically. In the limit of the adiabatic condition, this phase exactly reduces to the adiabatic geometric phase. To illustrate the present theory, two solvable time-dependent systems are considered.
SYMMETRY AND SYNCHRONY IN COUPLED CELL NETWORKS 3
Authors: ANTONELI FERNANDO , STEWART IAN
Published: April 2008

This paper continues the study of patterns of synchrony (equivalently, balanced colorings or flow-invariant subspaces) in symmetric coupled cell networks, and their relation to fixed-point spaces of subgroups of the symmetry group. Our aim is to provide a group-theoretic explanation of the "exotic" balanced coloring previously discussed in Part 2. Here we show that the pattern can be obtained as a projection into two dimensions of a fixed-point pattern in a three-dimensional lattice. We prove a general theorem giving sufficient conditions for such a construction to lead to a balanced coloring, for an arbitrary direct product of group networks.
THE MOSAIC PATTERNS OF CNN WITH SYMMETRIC FEEDBACK TEMPLATE
Authors: KE YUNQUAN
Published: April 2008

In this paper, the mosaic patterns of the two-dimensional cellular neural network (CNN) with symmetric feedback template are investigated. For our CNN system, the parameter space is constructed by the output synaptic weights and the threshold, and it is partitioned into finitely many regions through geometric methods and variable substitution. Fixing the output synaptic weights and the threshold in some regions, we give the necessary and sufficient conditions to all mosaic patterns of the CNN systems.
PRECESSION AND CHAOS IN THE CLASSICAL TWO-BODY PROBLEM IN A SPHERICAL UNIVERSE
Authors: LINDNER JOHN F. , ROSEBERRY MARTHA I. , SHAI DANIEL E. , HARMON NICHOLAS J. , OLAKSEN KATHERINE D.
Published: April 2008

We generalize the classical two-body problem from flat space to spherical space and realize much of the complexity of the classical three-body problem with only two bodies. We show analytically, by perturbation theory, that small, nearly circular orbits of identical particles in a spherical universe precess at rates proportional to the square root of their initial separations and inversely proportional to the square of the universe's radius. We show computationally, by graphically displaying the outcomes of large open sets of initial conditions, that large orbits can exhibit extreme sensitivity to initial conditions, the signature of chaos. Although the spherical curvature causes nearby geodesics to converge, the compact space enables infinitely many close encounters, which is the mechanism of the chaos.
BIFURCATIONS FROM PLANAR TO THREE-DIMENSIONAL PERIODIC ORBITS IN THE PHOTO-GRAVITATIONAL RESTRICTED FOUR-BODY PROBLEM
Authors: KALVOURIDIS T. J. , HADJIFOTINOU K. G.
Published: April 2008

We study the bifurcations of three-dimensional periodic motions from two-dimensional orbits of small particles in the neighborhood of a system that consists of three major bodies being always in syzygy. We assume that two of them have equal masses and are located at equal distances from the third body which has a different mass. All or some of the primaries are radiation sources and therefore apart from gravitational forces, we also consider forces that result from radiation. We apply the method of vertical critical stability in order to find the families of three-dimensional periodic orbits that bifurcate from families of planar periodic motions. Consequently, we study the parametric variations of the bifurcation points.
INTERMITTENT OPERATION OF LINEAR DRIVEN SWITCHED SYSTEMS
Authors: CERVANTES I. , FEMAT R.
Published: April 2008

The phenomenon of breathing (intermittent operation) is studied in a class of piecewise continuous systems as well as its relation with system parameters.

The class of systems under study comprises a continuous time subsystem and a switching rule that induces an oscillatory path by switching alternately between stable and unstable conditions. An interesting feature of the system is that eigenvalues of linear subsystems play an important role in system evolution.

It is shown that although regular and chaotic phases evolve irregularly for a given system, their average behavior is surprisingly regular with respect to a bifurcation parameter. It is found that the phenomenon of breathing share some structural characteristics with intermittency; i.e. existence of a critical exponent. However, for switched systems, many critical exponents may be required. Bifurcation maps and other analysis tools allow us to gain insight into the origin of breathing. This work constitutes a first step toward the characterization of intermittent operation in piecewise continuous systems.
ELECTRON TRAPPING BY SOLITONS: CLASSICAL VERSUS QUANTUM MECHANICAL APPROACH
Authors: VELARDE MANUEL G. , EBELING WERNER , CHETVERIKOV ALEXANDER P. , HENNIG DIRK
Published: April 2008

Assuming either classical electrodynamics or the quantum mechanical tight-binding of an electron to a nonlinear lattice with exponentially repulsive potential interactions we show how in both cases electron trapping can be mediated by solitons thus forming similar robust bound states (solectrons).
TIME SCALING OF CHAOTIC SYSTEMS: APPLICATION TO SECURE COMMUNICATIONS
Authors: MATERASSI DONATELLO , BASSO MICHELE
Published: April 2008

The paper deals with time-scaling transformations of dynamical systems. Such scaling functions operate a change of coordinates on the time axis of the system trajectories preserving its phase portrait. Exploiting this property, a chaos encryption technique to transmit a binary signal through an analog channel is proposed. The scheme is based on a suitable time-scaling function which plays the role of a private key. The encoded transmitted signal is proved to resist known decryption attacks offering a secure and reliable communication.
BORDER COLLISION BIFURCATIONS IN THREE-DIMENSIONAL PIECEWISE SMOOTH SYSTEMS
Authors: ROY INDRAVA , ROY A. R.
Published: April 2008

Piecewise smooth maps have been a focus of study for scientists in a wide range of research fields. These maps show qualitatively different types of bifurcations than those exhibited by generic smooth maps. We present a theoretical framework for analyzing three-dimensional piecewise smooth maps by deriving a suitable normal form and then finding the stability criteria for periodic orbits. We also show by numerical simulation different types of border collision bifurcations that can occur in such a map. We have also been able to observe a border collision bifurcation from a period-2 to a quasiperiodic orbit.
CLUSTER SPLITTING TRANSITION IN A MARKOV CHAIN MODEL FOR LABOR DIVISION
Authors: CHAI LEI , WANG DAHUI , CHEN JIAWEI , LI MENGHUI , DI ZENGRU
Published: April 2008

A Markov chain model is constructed to simulate pattern formation arising from an evolutionary population of interactive homogeneous agents. In the structure of optimal evolution and stochastic properties, the model exhibits emergent properties with rich dynamical diagrams. We study the cluster splitting transition with the coarsening period-adding phenomena shown by the model, which gives an example of pattern formation in the evolution of complex system and reveals dynamical behavior of the Markov chain process.
Cardiac overexpression of hormone-sensitive lipase inhibits myocardial steatosis and fibrosis in streptozotocin diabetic mice
Authors: Ueno Masami , Suzuki Jinya , Zenimaru Yasuo , Takahashi Sadao , Koizumi Tsutomu , Noriki Sakon , Yamaguchi Osamu , Otsu Kinya , Shen Wen-Jun , Kraemer Fredric B. , Miyamori Isamu
Published: April 2008

Intracellular lipid accumulation (steatosis) and resultant lipotoxicity are key features of diabetic cardiomyopathy. Since cardiac hormone-sensitive lipase (HSL) is activated in diabetic mice, we sought to explore a pathophysiological function of cardiac HSL in the development of diabetic cardiomyopathy. Transgenic (Tg) mice with heart-specific HSL overexpression were generated, and cardiac histology, function, lipid profile, and gene expressions were analyzed after induction of diabetes by streptozotocin. Electron microscopy showed numerous lipid droplets in wild-type (Wt) hearts after 3 wk of diabetes, whereas Tg mice showed no lipid droplet accumulation. Cardiac content of acylglycerides was increased ∼50% with diabetes in Wt mice, whereas this was blunted in Tg hearts. Cardiac lipid peroxide content was twofold lower in Tg hearts than in Wt hearts. The mRNA expressions for peroxisome proliferator-activated receptor-α, genes for triacylglycerol synthesis, and lipoprotein lipase were increased with diabetes in Wt hearts, whereas this induction was absent in Tg hearts. Expression of genes associated with lipoapoptosis was decreased, whereas antioxidant protein metallothioneins were increased in diabetic Tg hearts. Diabetic Wt hearts showed interstitial fibrosis and increased collagen content. However, Tg hearts displayed no overt fibrosis, concomitant with decreased expression of collagens, transforming growth factor-β, and matrix metalloproteinase 2. Notably, mortality during the experimental period was approximately twofold lower in diabetic Tg mice compared with Wt mice. In conclusion, since HSL overexpression inhibits cardiac steatosis and fibrosis by apparently hydrolyzing toxic lipid metabolites, cardiac HSL could be a therapeutic target for regulating diabetic cardiomyopathy.
Exogenous stromal cell-derived factor-1 induces modest leukocyte recruitment in vivo
Authors: Kerfoot Steven M. , Andonegui Graciela , Bonder Claudine S. , Liu Lixin
Published: April 2008

Stromal cell-derived factor-1 (SDF-1; CXCL12), a CXC chemokine, has been found to be involved in inflammation models in vivo and in cell adhesion, migration, and chemotaxis in vitro. This study aimed to determine whether exogenous SDF-1 induces leukocyte recruitment in mice. After systemic administration of SDF-1α, expression of the adhesion molecules P-selectin and VCAM-1 in mice was measured using a quantitative dual-radiolabeled Ab assay and leukocyte recruitment in various tissues was evaluated using intravital microscopy. The effect of local SDF-1α on leukocyte recruitment was also determined in cremaster muscle and compared with the effect of the cytokine TNFα and the CXC chemokine keratinocyte-derived chemokine (KC; CXCL1). Systemic administration of SDF-1α (10 μg, 4–5 h) induced upregulation of P-selectin, but not VCAM-1, in most tissues in mice. It caused modest leukocyte recruitment responses in microvasculature of cremaster muscle, intestine, and brain, i.e., an increase in flux of rolling leukocytes in cremaster muscle and intestines, leukocyte adhesion in all three tissues, and emigration in cremaster muscle. Local treatment with SDF-1α (1 μg, 4–5 h) reduced leukocyte rolling velocity and increased leukocyte adhesion and emigration in cremasteric venules, but the responses were much less profound than those elicited by KC or TNFα. SDF-1α-induced recruitment was dependent on endothelial P-selectin, but not P-selectin on platelets. We conclude that the exogenous SDF-1α enhances leukocyte-endothelial cell interactions and induces modest and endothelial P-selectin-dependent leukocyte recruitment.
Effect of chronic and selective endothelin receptor antagonism on microvascular function in Type 2 diabetes
Authors: Sachidanandam Kamakshi , Elgebaly Mostafa M. , Harris Alex K. , Hutchinson Jim R. , Mezzetti Erin M. , Portik-Dobos Vera , Ergul Adviye
Published: April 2008

Vascular dysfunction, which presents either as an increased response to vasoconstrictors or an impaired relaxation to dilator agents, results in worsened cardiovascular outcomes in diabetes. We have established that the mesenteric circulation in Type 2 diabetes is hyperreactive to the potent vasoconstrictor endothelin-1 (ET-1) and displays increased nitric oxide-dependent vasodilation. The current study examined the individual and/or the relative roles of the ET receptors governing vascular function in the Goto-Kakizaki rat, a mildly hyperglycemic, normotensive, and nonobese model of Type 2 diabetes. Diabetic and control rats received an antagonist to either the ET type A (ETA; atrasentan; 5 mg·kg−1·day−1) or type B (ETB; A-192621; 15 or 30 mg·kg−1·day−1) receptors for 4 wk. Third-order mesenteric arteries were isolated, and vascular function was assessed with a wire myograph. Maximum response to ET-1 was increased in diabetes and attenuated by ETAantagonism. ETBblockade with 15 mg/kg A-192621 augmented vasoconstriction in controls, whereas it had no further effect on ET-1 hyperreactivity in diabetes. The higher dose of A-192621 showed an ETA-like effect and decreased vasoconstriction in diabetes. Maximum relaxation to acetylcholine (ACh) was similar across groups and treatments. ETBantagonism at either dose had no effect on vasorelaxation in control rats, whereas in diabetes the dose-response curve to ACh was shifted to the right, indicating a decreased relaxation at 15 mg/kg A-192621. These results suggest that ETAreceptor blockade attenuates vascular dysfunction and that ETBreceptor antagonism exhibits differential effects depending on the dose of the antagonists and the disease state.
Dynamics of sleep stage transitions in healthy humans and patients with chronic fatigue syndrome
Authors: Kishi Akifumi , Struzik Zbigniew R. , Natelson Benjamin H. , Togo Fumiharu , Yamamoto Yoshiharu
Published: April 2008

Physiological and/or pathological implications of the dynamics of sleep stage transitions have not, to date, been investigated. We report detailed duration and transition statistics between sleep stages in healthy subjects and in others with chronic fatigue syndrome (CFS); in addition, we also compare our data with previously published results for rats. Twenty-two healthy females and 22 female patients with CFS, characterized by complaints of unrefreshing sleep, underwent one night of polysomnographic recording. We find that duration of deep sleep (stages III and IV) follows a power-law probability distribution function; in contrast, stage II sleep durations follow a stretched exponential and stage I, and REM sleep durations follow an exponential function. These stage duration distributions show a gradually increasing departure from the exponential form with increasing depth of sleep toward a power-law type distribution for deep sleep, suggesting increasing complexity of regulation of deeper sleep stages. We also find a substantial number of REM to non-REM sleep transitions in humans, while this transition is reported to be virtually nonexistent in rats. The relative frequency of this REM to non-REM sleep transition is significantly lower in CFS patients than in controls, resulting in a significantly greater relative transition frequency of moving from both REM and stage I sleep to awake. Such an alteration in the transition pattern suggests that the normal continuation of sleep in light or REM sleep is disrupted in CFS. We conclude that dynamic transition analysis of sleep stages is useful for elucidating yet-to-be-determined human sleep regulation mechanisms with pathophysiological implications.
Synaptic Commitment: Developmentally Regulated Reciprocal Changes in Hippocampal Granule Cell NMDA and AMPA Receptors Over the Lifespan
Authors: Yang Zhiyong , Krause Michael , Rao Geeta , McNaughton Bruce L. , Barnes C. A.
Published: April 2008

Synaptic transmission in hippocampal field CA1 is largely N-methyl-d-aspartate receptor (NMDAR) dependent during the early postnatal period. It becomes increasingly mediated by α-amino-3-hydroxy-5-methylisoxazole-4-proprionate (AMPA) receptors until an adult ratio of AMPA to NMDA receptors is achieved. It is shown here that increases in the AMPA receptor (AMPAR)-mediated field potential response continue over the life span of the F-344 rat at the perforant path–granule cell synapse in the dentate gyrus. In contrast, the NMDAR-dependent component of the response decreases with age between 1 and 27 mo, leading to an increase of AMPAR/NMDAR ratio with age. One possible explanation of this age difference is that the AMPAR/NMDAR ratio can be modified by experience. To test the idea that the changed ratio is caused by the old rats' longer lives, an intensive 10-mo period of enrichment treatment was given to a group of animals, beginning at 3 mo of age. Compared with animals housed in standard cages, the enrichment treatment did not alter the glutamatergic response ratio measured with field potential recording methods. These data provide support for the conclusion that the observed change with age is developmentally regulated rather than experience dependent. Given the role of the NMDAR in synaptic plasticity, these changes suggest a progressive commitment of perforant path synapses to particular weights over the life span. One possible implication of this effect includes preservation of selected memories, ultimately at the expense of a reduced capacity to store new information.
Current challenges in metabolomics for diabetes research: a vital functional genomic tool or just a ploy for gaining funding?
Authors: Griffin Julian L. , Vidal-Puig Antonio
Published: April 2008

Metabolomics aims to profile all the small molecule metabolites found within a cell, tissue, organ, or organism and use this information to understand a biological manipulation such as a drug intervention or a gene knockout. While neither mass spectrometry or NMR spectroscopy, the two most commonly used analytical tools in metabolomics, can provide a complete coverage of the metabolome, compared with other functional genomic tools for profiling biological moieties the approach is cheap and high throughput. In diabetes and obesity research this has provided the opportunity to assess large human populations or investigate a range of different tissues in animal studies both rapidly and cheaply. However, the approach has a number of major challenges, particularly with the interpretation of the data obtained. For example, some key pathways are better represented by high concentration metabolites inside the cell, and thus, the coverage of the metabolome may become biased towards these pathways (e.g., the TCA cycle, amino acid metabolism). There is also the challenge of statistically modeling datasets with large numbers of variables but relatively small sample sizes. This perspective discusses our own experience of some of the benefits and pitfalls with using metabolomics to understand diseases associated with type 2 diabetes.
Overlapping genes inNalp6/PYPAF5locus encode two V2-type vasopressin isoreceptors: angiotensin-vasopressin receptor (AVR) and non-AVR
Authors: Herrera Victoria L. M. , Bagamasbad Pia , Didishvili Tamara , Decano Julius L. , Ruiz-Opazo Nelson
Published: April 2008

The angiotensin-vasopressin receptor (AVR) responds with equivalent affinities to angiotensin II (ANG II) and vasopressin and is coupled to adenylate cyclase and hence a V2-type vasopressin receptor. AVR maps to the Nalp6 locus and overlaps with the larger Nalp6/PYPAF5 reported to be a T cell/granulocyte-specific, cytoplasmic-specific proapoptotic protein, thus questioning the existence of AVR. Here we confirm, through different experimental modalities, that AVR is distinct from Nalp6/PYPAF5 based on different mRNA and protein sizes, subcellular localization, and tissue-specific expression patterns. Binding studies of PYPAF5-specific Cos1 transfectants detect high-affinity binding to vasopressin but not ANG II, thus assigning PYPAF5 as a non-AVR (NAVR). Signaling array analysis reveals that AVP stimulation of AVR- and NAVR-specific Cos1 transfectants results in diametrical activation as well as coactivation of signaling pathways known to mediate renal sodium and water balance. Likewise, ANG II stimulation of Cos1-AVR transfectants reveals a signaling profile distinct from that of AVP-stimulated Cos1-AVR transfectants. Analysis of genomic organization of the AVR/NAVR locus shows an overlapping gene arrangement with alternative promoter usage resulting in different NH2termini for NAVR and AVR. In addition to core promoter elements, androgen and estrogen response elements are detected. Promoter analysis of NAVR/AVR 5′-regulatory region detects transcriptional upregulation by testosterone and synergistic upregulation by testosterone and estrogen, thus suggesting that AVR and/or NAVR contribute to sex-specific V2-type vasopressin-mediated effects. Altogether, confirmation of AVR and identification of NAVR as vasopressin receptors are concordant with emerging vasopressin functions not attributable to V1a, V1b, or V2 receptors and add molecular bases for the multifunctional complexity of vasopressin-mediated functions and regulation.
Markedly Different Clinical Features in 2 Diabetes Mellitus Patients with Extremely High Tissue Levels of the Mitochondrial DNA A3243G Mutation
Authors: Harihara Shinji , Nakamura Kenichi , Fujiwara Mutsunori , Arai Tomio , Sawabe Motoji , Takeuchi Fujio , Takubo Kaiyo
Published: April 2008

Background: Mitochondrial DNA (mtDNA) A3243G mutation is one of the major causative factors of mitochondrial diabetes mellitus. We found that tissues from 2 of 142 diabetes mellitus patients showed extremely high levels of the mutation. Objective: To investigate the level of the mutation in each tissue and to find the relationship between the mutation level and clinical features of the patients. Methods: Patient 1 was a 51-year-old woman, diagnosed as having diabetes mellitus at the age of 17, and was admitted to hospital because of cerebral infarction. Patient 2 was an 82-year-old woman who was admitted because of respiratory failure. mtDNA A3243G levels were measured in tissues collected at autopsy. Results: In patient 1, mtDNA A3243G levels were found to vary among the tissues. The patient’s highest mtDNA A3243G value was 42% and the lowest value was 9%, whereas the level in most individuals is usually less than 1%. Although patient 2 did not exhibit serious clinical symptoms of diabetes mellitus, the mtDNA A3243G level was extremely high in all of the tissues surveyed (range 32–47%). Conclusion: Although both patients showed high levels of the mtDNA A3243G mutation, their clinical conditions differed greatly. Thus, mitochondrial diabetes mellitus patients may show a wide variety of clinical features and large variations in life span.
Rapid Electrophysiological Brain Responses are Influenced by Both Valence and Magnitude of Monetary Rewards
Authors: Goyer Julia P. , Woldorff Marty G. , Huettel Scott A.
Published: April 2008

Negative outcomes, as identified from external feedback, cause a short-latency negative deflection in the event-related potential (ERP) waveform over medial frontal electrode sites. This brain response, which has been called an “error related negativity” (ERN) or “medial frontal negativity” (MFN), may reflect a coarse evaluation of performance outcomes, such as the valence of a reward within a monetary gambling task. Yet, for feedback to lead to the adaptive control of behavior, other information concerning reward outcomes besides experienced valence may also be important. Here, we used a gambling task in which subjects chose between two options that could vary in both outcome valence (gain or loss) and outcome magnitude (larger or smaller). We measured changes in brain ERP responses associated with the presentation of the outcomes. We found, as shown in prior studies, that valence of the chosen outcome has an early effect upon frontal ERPs, with maximal difference observed at ∼250 msec. However, our results demonstrated that the early ERP responses to outcome feedback were driven not just by valence but by the combination of valence and magnitude for both chosen and unchosen options. Beginning even earlier, at around 150 msec, responses to high-consequence outcomes resulted in a greater, more centrally distributed, positive potential than those involving low-consequence outcomes, independent of valence. Furthermore, the amplitude of these early effects was significantly modulated by the sequence of outcomes in previous trials. These results indicate that early evaluation of feedback goes beyond simple identification of valence—it involves the consideration of multiple factors, including outcome magnitude, context of unchosen options, and prior history.
Gamma Band Synchronization and the Formation of Representations in Visual Word Processing: Evidence from Repetition and Homophone Priming
Authors: Matsumoto Atsushi , Iidaka Tetsuya
Published: April 2008

The formation of an object's cortical representation seems to rely on synchronized neuronal activity within the gamma band frequency range (gamma band activity [GBA]). In this study, we investigated whether electroencephalogram (EEG) GBA, and its phase synchronization between electrodes, is necessary for the formation of nonobject higher-order cognitive representations, using both repetition and homophone priming tasks. In a repetition priming task, the formation of orthographic, phonological, and semantic representations is promoted by a prime word, whereas in the homophone priming task, the formation of only phonological representations is promoted. In the present study, the lexical processing of a target word induced GBA. In the repetition priming task, induced GBA and phase synchronization were decreased by presentation of the prime word (i.e., a repetition suppression effect) within both 200–300 msec and 400–500 msec time windows. In the homophone priming task, the repetition suppression effect was observed only within the 400–500 msec time window. The fact that repetition suppression effects were found in both priming tasks indicates that GBA and phase synchronization are necessary for the formation of phonological and semantic representations of a word. These results also suggest that formation of orthographic and higher-order cognitive representations occurred over different time courses.
Neural Activity within Area V1 Reflects Unconscious Visual Performance in a Case of Blindsight
Authors: Radoeva Petya D. , Prasad Sashank , Brainard David H. , Aguirre Geoffrey K.
Published: April 2008

Although lesions of the striate (V1) cortex disrupt conscious vision, patients can demonstrate surprising residual abilities within their affected visual field, a phenomenon termed blindsight. The relative contribution of spared “islands” of functioning striate cortex to residual vision, versus subcortical pathways to extrastriate areas, has implications for the role of early visual areas in visual awareness and performance. Here we describe the behavioral and neural features of residual cortical function in Patient M.C., who sustained a posterior cerebral artery stroke at the age of 15 years. Within her impaired visual field, we found preserved visual abilities characteristic of blindsight, including superior detection of motion, and above-chance discrimination of shape, color, and motion direction. Functional magnetic resonance imaging demonstrated a retinotopically organized representation of M.C.'s blind visual field within the lesioned occipital lobe, specifically within area V1. The incongruity of a well-organized cortex and M.C.'s markedly impaired vision was resolved by measurement of functional responses within her damaged occipital lobe. Attenuated neural contrast-response functions were found to correlate with M.C.'s impaired psychophysical performance. These results demonstrate that the behavioral features of blindsight may arise in the presence of residual striate responses that are spatially organized and sensitive to contrast variation.