bluuebunny/crossref_metadata_2025 huggingface dataset:
SMALL PURE CARBON MOLECULES WITH SMALL-WORLD NETWORKS USING DENSITY FUNCTIONAL THEORY SIMULATIONS
Authors: YANCEY JEREMY A. , NOVOTNY M. A. , GWALTNEY STEVEN R.
Published: October 2009

The possible existence of small, pure carbon molecules based on small-world networks is addressed using density functional theory simulations. A ring of atoms with one or more small-world connections between pairs of non-nearest-neighbor sites was chosen for the network topology. The small-world connections are made with and without additional carbon atoms placed along the link. The energy per atom of these small-world carbon systems is compared with benchmark molecules such as the C 20 ring, bowl, and cage isomers, the C 60 Buckyball, monocyclic pure carbon rings ranging from C 4 to C 60, bare linear carbon chains ranging from C 2 to C 36, and various graphitic fragments without hydrogens. The results of the energy per atom for some of these small-world clusters provide an indication that such pure carbon molecules are reasonable for real world synthesis.
TWO-DIMENSIONAL WANG–LANDAU SAMPLING OF AN ASYMMETRIC ISING MODEL
Authors: TSAI SHAN-HO , WANG FUGAO , LANDAU D. P.
Published: October 2009

We study the critical endpoint behavior of an asymmetric Ising model with two- and three-body interactions on a triangular lattice, in the presence of an external field. We use a two-dimensional Wang–Landau sampling method to determine the density of states for this model. An accurate density of states allowed us to map out the phase diagram accurately and observe a clear divergence of the curvature of the spectator phase boundary and of the derivative of the magnetization coexistence diameter near the critical endpoint, in agreement with previous theoretical predictions.
A HYBRID, QUANTUM-CLASSICAL APPROACH FOR THE COMPUTATION OF DISLOCATION PROPERTIES IN REAL MATERIALS: METHOD, LIMITATIONS AND APPLICATIONS
Authors: TAVAZZA FRANCESCA , LEVINE LYLE E. , CHAKA ANNE M.
Published: October 2009

In this work we introduce a hybrid ab initio-classical simulation methodology designed to incorporate the chemistry into the description of phenomena that, intrinsically, require very large systems to be properly described. This hybrid approach allows us to conduct large-scale atomistic simulations with a simple classical potential (embedded atom method (EAM), for instance) while simultaneously using a more accurate ab initio approach for critical embedded regions. The coupling is made through shared atomic shells where the two atomistic modeling approaches are relaxed in an iterative, self-consistent manner. The magnitude of the incompatibility forces arising in the shared shell is analyzed, and possible terminations for the embedded region are discussed, as a way to reduce such forces. As a test case, the formation energy of a single vacancy in aluminum at different distances from an edge dislocation is studied. Results obtained using the hybrid approach are compared to those obtained using classical methods alone, and the range of validity for the classical approach is evaluated.
VISUALIZING COMPLICATED QUANTUM MECHANICAL BEHAVIOR FROM SIMPLE 2D POTENTIALS USING WEBTOP
Authors: YANCEY AMBER N. , KIM SEONG-GON , FOLEY JOHN T.
Published: October 2009

The ability to simulate several aspects of two-dimensional quantum mechanics is discussed, in conjunction with an ongoing visualization project, WebTOP, that has been of recognizable importance to physics education since its inception in the late 1990s. In the past, the WebTOP project has been primarily used as a means of visualizing optics and wave phenomena and, now, the development of certain interactive quantum mechanical demonstrations has the potential to strengthen its power as an educational tool for the physics community. The added functionality for propagating wave packets forward in time for a given 2D potential gives rise to the ability to investigate interesting quantum behaviors. Fractional revivals of states in the 2D infinite square well can be clearly seen as well as the time delay of scattered wave packets for certain step potentials. Aspects of squeezed and coherent states of the 2D harmonic oscillator potential can also be explored, among other observable phenomena.
MESOSCALE COMPUTER SIMULATIONS OF POLYMER-TETHERED ORGANIC/INORGANIC NANOCUBE SELF-ASSEMBLY
Authors: CHAN ELAINE R. , HO LIN C. , GLOTZER SHARON C.
Published: October 2009

A molecular simulation study of the mesoscale self-assembly of tethered nanoparticles having a cubic geometry is presented. Minimal models of the tethered nanocubes are developed to represent a polyhedral oligomeric silsesquioxane (POSS) molecule with polymeric substituents. The models incorporate some of the essential structural features and interaction specificity of POSS molecules, and facilitate access to the long length and timescales pertinent to the assembly process while foregoing atomistic detail. The types of self-assembled nanostructures formed by the tethered nanocubes in solution are explored via Brownian dynamics simulations using these minimal models. The influence of various parameters, including the conditions of the surrounding medium, the molecular weight and chemical composition of the tether functionalities, and the number of tethers on the nanocube, on the formation of specific structures is demonstrated. The role of cubic nanoparticle geometry on self-assembly is also assessed by comparing the types of structures formed by tethered nanocubes and by their flexible coil triblock copolymer and tethered nanosphere counterparts. Morphological phase diagrams are proposed to describe the behavior of the tethered nanocubes.
FRUSTRATED METALS ON A TRIANGULAR LATTICE
Authors: FURUKAWA NOBUO , MIYAHARA SHIN , HOTTA C.
Published: October 2009

Frustrated metals are investigated by numerical methods. In the absence of fermionic dynamics, the models are equivalent to a frustrated Ising model on a geometrically frustrated lattice, where macroscopic degeneracies are observed in the ground states. By taking into account fermionic hoppings, the models show partial loss of degeneracy, but still remains to be frustrated. Various properties of the system, including charge correlations, are also examined.
GENERA AND DEGREES OF TORUS KNOTS IN ℂP2
Authors: NOUH MOHAMED AIT
Published: October 2009

The ℂP2-genus of a knot K is the minimal genus over all isotopy classes of smooth, compact, connected and oriented surfaces properly embedded in ℂP2 - B4 with boundary K. We compute the ℂP2-genus and realizable degrees of (-2,q)-torus knots for 3 ≤ q ≤ 11 and (2,q)-torus knots for 3 ≤ q ≤ 17. The proofs use gauge theory and twisting operations on knots.
COLORINGS OF TORUS KNOTS AND THEIR TWIST-SPUNS BY ALEXANDER QUANDLES OVER FINITE FIELDS
Authors: ASAMI SOICHIRO , KUGA KEN'ICHI
Published: October 2009

Colorings of torus knots and twist-spun torus knots by general Alexander quandles over finite fields are explicitly determined. It is then observed that, for some standard Mochizuki's cocycles, a large class of twist-spun torus knots with non-trivial colorings have trivial CJKLS state-sum invariants.
MULTIWAVELETS AND APPLICATIONS TO IMAGE DENOISING WITH EFFECTIVE ITERATION METHOD
Authors: JUNG TAE KWON
Published: October 2009

The multiscaling function of Alpert multiwavelet system and Chui–Lian multiwavelet system consist of one symmetric and one antisymmetric scaling functions. In its single level decomposition, only one of 16 subband blocks may be considered as a core part because the antisymmetric scaling function may play the high pass filter. We complete the Alpert multiwavelet system by determining the high pass filter using the algorithm of paraunitary extension principle. Taking the advantage of the symmetric/antisymmetric (SA) feature of Alpert and Chui–Lian multiscaling functions, our iteration (SA iteration) of multiwavelet decomposition continues to the core part (1/16 of subbands) for the image denoising problem while the traditional iteration applies to the one fourth of 16 subbands as core parts. The numerical results demonstrate that our method of symmetric/antisymmetric iteration exhibits performance superior to the traditional ways.
VECTOR-VALUED WEYL–HEISENBERG WAVELET FRAME
Authors: AHMAD M. K. , IQBAL JAVID
Published: October 2009

This paper deals with the theory of frames for vector-valued Weyl–Heisenberg wavelets (VVWHW). We derive frame and the corresponding frame bounds for VVWHW.
BEARING FAULT DETECTION AND DIAGNOSIS BASED ON TEAGER–HUANG TRANSFORM
Authors: LI HUI , ZHENG HAIQI , TANG LIWEI
Published: October 2009

A new approach to fault diagnosis of bearings based on the Teager–Huang Transform (THT) is presented. This method is based on the Empirical Mode Decomposition (EMD) and Teager Kaiser Energy Operator (TKEO) techniques. EMD can adaptively decompose the vibration signal into a series of zero mean Amplitude Modulation-Frequency Modulation (AM-FM) Intrinsic Mode Functions (IMFs). TKEO can track the instantaneous amplitude and instantaneous frequency of the AM-FM component at any instant. The experimental examples are conducted to evaluate the effectiveness of the proposed approach. The experimental results provide strong evidence that the performance of the Teager–Huang Transform approach is better than that of the Hilbert–Huang Transform approach for bearing fault detection. The Teager–Huang Transform has better resolution than the Hilbert–Huang Transform. The Teager–Huang Transform can effectively diagnose the faults of the bearing, thus providing a viable processing tool for gearbox defect monitoring.
ON EXISTENCE AND UNIQUENESS OF ENTROPY SOLUTIONS TO THE CAUCHY PROBLEM FOR A CONSERVATION LAW WITH DISCONTINUOUS FLUX
Authors: PANOV E. YU.
Published: October 2009

We study the Cauchy problem for a conservation law with space discontinuous flux of generalized Audusse–Perthame form. It is shown that, after a change of unknown function, entropy solutions in the sense of Audusse–Perthame correspond to Kruzhkov's generalized entropy solutions for the transformed equation. This observation allows to use the Kruzhkov method of doubling variable (instead of rather complicated variant of this method invented by Audusse and Perthame). Applying this method for measure-valued solutions, we establish the uniqueness and the existence of entropy solutions to the problem under consideration.
ENERGY CRITICAL NLS IN TWO SPACE DIMENSIONS
Authors: COLLIANDER J. , IBRAHIM S. , MAJDOUB M. , MASMOUDI N.
Published: October 2009

We investigate the initial value problem for a defocusing nonlinear Schrödinger equation with exponential nonlinearity [Formula: see text] We identify subcritical, critical, and supercritical regimes in the energy space. We establish global well-posedness in the subcritical and critical regimes. Well-posedness fails to hold in the supercritical case.
GLOBAL WELL-POSEDNESS OF THE 1D DIRAC–KLEIN–GORDON SYSTEM IN SOBOLEV SPACES OF NEGATIVE INDEX
Authors: TESFAHUN ACHENEF
Published: October 2009

We prove that the Cauchy problem for the Dirac–Klein–Gordon system of equations in 1D is globally well-posed in a range of Sobolev spaces of negative index for the Dirac spinor and positive index for the scalar field. The main ingredient in the proof is the theory of "almost conservation law" and "I-method" introduced by Colliander, Keel, Staffilani, Takaoka, and Tao. Our proof also relies on the null structure in the system, and bilinear space–time estimates of Klainerman–Machedon type.
JUSTIFICATION OF HOMOGENIZATION IN VISCOPLASTICITY: FROM CONVERGENCE ON TWO SCALES TO AN ASYMPTOTIC SOLUTION IN L2(Ω)
Authors: ALBER HANS-DIETER , NESENENKO SERGIY
Published: October 2009

A homogenized material model can be used effectively for simulation, if the difference of the solutions of this model and the microscopic model converges to zero in a strong norm when the microstructure is scaled. The second author recently showed for the quasistatic initial-boundary value problem with internal variables modeling an inelastic solid body Ω at small strain that this convergence holds in an averaged sense over phase shifts of the microstructure. Based on this result, we construct an asymptotic solution, which converges to the solution of the microscopic problem in the L2(Ω)-norm, thus avoiding the averaging.
ON MACHIN'S FORMULA WITH POWERS OF THE GOLDEN SECTION
Authors: LUCA FLORIAN , STĂNICĂ PANTELIMON
Published: October 2009

In this note, we find all solutions of the equation π/4 = a arctan (ϕκ) + b arctan (ϕℓ), in integers κ and ℓ and rational numbers a and b, where ϕ is the golden section.
DIFFERENTIAL ACTIONS ON THE ASYMPTOTIC EXPANSIONS OF NON-HOLOMORPHIC EISENSTEIN SERIES
Authors: KATSURADA MASANORI , NODA TAKUMI
Published: October 2009

Let k be an arbitrary even integer, and Ek(s;z) denote the non-holomorphic Eisenstein series (of weight k attached to SL2(ℤ)), defined by (1.1) below. In the present paper we first establish a complete asymptotic expansion of Ek(s;z) in the descending order of y as y → + ∞ (Theorem 2.1), upon transferring from the previously derived asymptotic expansion of E0(s;z) (due to the first author [16]) to that of Ek(s;z) through successive use of Maass' weight change operators. Theorem 2.1 yields various results on Ek(s;z), including its functional properties (Corollaries 2.1–2.3), its relevant specific values (Corollaries 2.4–2.7), and its asymptotic aspects as z → 0 (Corollary 2.8). We then apply the non-Euclidean Laplacian ΔH,k (of weight k attached to the upper-half plane) to the resulting expansion, in order to justify the eigenfunction equation for Ek(s;z) in (1.6), where the justification can be made uniformly in the whole s-plane (Theorem 2.2).
ON GENERAL SERIES-PRODUCT IDENTITIES
Authors: CHEN SIN-DA , HUANG SEN-SHAN
Published: October 2009

We derive the general series-product identities from which we deduce several applications, including an identity of Gauss, the generalization of Winquist's identity by Carlitz and Subbarao, an identity for [Formula: see text], the quintuple product identity, and the octuple product identity.
Expression of plasmid DNA in the salivary gland epithelium: novel approaches to study dynamic cellular processes in live animals
Authors: Sramkova Monika , Masedunskas Andrius , Parente Laura , Molinolo Alfredo , Weigert Roberto
Published: October 2009

The ability to dynamically image cellular and subcellular structures in a live animal and to target genes to a specific cell population in a living tissue provides a unique tool to address many biological questions in the proper physiological context. Here, we describe a powerful approach that is based on the use of rat submandibular salivary glands, which offer the possibility to easily perform intravital imaging and deliver molecules from the oral cavity, and plasmid DNA, which offers the advantage of rapid manipulations. We show that, under different experimental conditions, a reporter molecule can be rapidly expressed in specific compartments of the glands: 1) in the intercalated ducts, when plasmid DNA is administered alone, and 2) in granular ducts, striated ducts, and, to a lesser extent, acini, when plasmid DNA is mixed with replication-deficient adenovirus subtype 5 particles. Remarkably, we also found that gene expression can be directed to acinar cells when plasmid DNA is administered during isoproterenol-stimulated exocytosis, suggesting a novel mechanism of plasmid internalization regulated by compensatory endocytosis. Finally, as a practical application of these strategies, we show how the expression of fluorescently tagged molecules enables the study of the dynamics of various organelles in live animals at a resolution comparable to that achieved in cell cultures.
Heightened colon motor activity measured by a wireless capsule in patients with constipation: relation to colon transit and IBS
Authors: Hasler William L. , Saad Richard J. , Rao Satish S. , Wilding Gregory E. , Parkman Henry P. , Koch Kenneth L. , McCallum Richard W. , Kuo Braden , Sarosiek Irene , Sitrin Michael D. , Semler John R. , Chey William D.
Published: October 2009

Relationships of regional colonic motility to transit in health, constipation, and constipation-predominant irritable bowel syndrome (C-IBS) are poorly characterized. This study aimed to 1) characterize regional differences in colon pressure, 2) relate motor differences in constipation to colon transit, and 3) quantify the role of IBS in altered contractility with constipation. Colon pH and pressure were measured by wireless capsules in 53 healthy and 36 constipated subjects. Numbers of contractions >25 mmHg and areas under curves (AUC) were calculated for colon transit quartiles by time. Constipation was classified as normal transit (<59 h), moderate slow transit (STC) (59–100 h), and severe STC (>100 h). Twelve out of 36 constipated subjects had C-IBS; 24 had functional constipation. Numbers of contractions and AUCs increased from the first to the fourth quartile in health ( P < 0.0001). Mean numbers of contractions in constipated subjects were similar to controls. Mean AUCs with normal transit ( P = 0.01) and moderate STC ( P = 0.004) but not severe STC ( P = NS) were higher than healthy subjects. IBS was associated with greater mean numbers of contractions ( P = 0.05) and AUCs ( P = 0.0006) vs. controls independent of transit. Numbers of contractions increased from the first to fourth quartiles in moderate STC, C-IBS, and functional constipation; AUCs increased from the first to fourth quartiles in all groups (all P < 0.05). In conclusion, colon pressure activity is greater distally than proximally in health. Constipated patients with normal or moderately delayed transit show increased motor activity that is partly explained by IBS. These findings emphasize differential effects on transit and motility in different constipation subtypes.
Activation of adenosine low-affinity A3 receptors inhibits the enteric short interplexus neural circuit triggered by histamine
Authors: Bozarov Andrey , Wang Yu-Zhong , Yu Jun Ge , Wunderlich Jacqueline , Hassanain Hamdy H. , Alhaj Mazin , Cooke Helen J. , Grants Iveta , Ren Tianhua , Christofi Fievos L.
Published: October 2009

We tested the novel hypothesis that endogenous adenosine (eADO) activates low-affinity A3 receptors in a model of neurogenic diarrhea in the guinea pig colon. Dimaprit activation of H2 receptors was used to trigger a cyclic coordinated response of contraction and Cl−secretion. Contraction-relaxation was monitored by sonomicrometry (via intracrystal distance) simultaneously with short-circuit current ( Isc, Cl−secretion). The short interplexus reflex coordinated response was attenuated or abolished by antagonists at H2 (cimetidine), 5-hydroxytryptamine 4 receptor (RS39604), neurokinin-1 receptor (GR82334), or nicotinic (mecamylamine) receptors. The A1 agonist 2-chloro- N6-cyclopentyladenosine (CCPA) abolished coordinated responses, and A1 antagonists could restore normal responses. A1-selective antagonists alone [8-cyclopentyltheophylline (CPT), 1,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX), or 8-cyclopentyl- N3-[3-(4-(fluorosulfonyl)benzoyloxy)propyl]-xanthine (FSCPX)] caused a concentration-dependent augmentation of crypt cell secretion or contraction and acted at nanomolar concentrations. The A3 agonist N6-(3-iodobenzyl)-adenosine-5′- N-methyluronamide (IB-MECA) abolished coordinated responses and the A3 antagonist 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS1191) could restore and further augment responses. The IB-MECA effect was resistant to knockdown of adenosine A1 receptor with the irreversible antagonist FSCPX; the IC50for IB-MECA was 0.8 μM. MRS1191 alone could augment or unmask coordinated responses to dimaprit, and IB-MECA suppressed them. MRS1191 augmented distension-evoked reflex Iscresponses. Adenosine deaminase mimicked actions of adenosine receptor antagonists. A3 receptor immunoreactivity was differentially expressed in enteric neurons of different parts of colon. After tetrodotoxin, IB-MECA caused circular muscle relaxation. The data support the novel concept that eADO acts at low-affinity A3 receptors in addition to high-affinity A1 receptors to suppress coordinated responses triggered by immune-histamine H2 receptor activation. The short interplexus circuit activated by histamine involves adenosine, acetylcholine, substance P, and serotonin. We postulate that A3 receptor modulation may occur in gut inflammatory diseases or allergic responses involving mast cell and histamine release.
Insulin-like growth factor-binding protein-5 stimulates growth of human intestinal muscle cells by activation of Gαi3
Authors: Flynn Robert S. , Mahavadi Sunila , Murthy Karnam S. , Kellum John M. , Kuemmerle John F.
Published: October 2009

In human intestinal smooth muscle cells, endogenous insulin-like growth factor-I (IGF-I) regulates growth and IGF-binding protein-5 (IGFBP-5) expression. The effects of IGF-I are facilitated by IGFBP-5. We previously showed that IGFBP-5 acts independently of IGF-I in human intestinal muscle to stimulate proliferation and upregulate IGF-I production by activation of Erk1/2 and p38 MAPK. Thus a positive feedback loop exists between IGF-I and IGFBP-5, whereby both stimulate muscle growth and production of the other factor. In Crohn's disease, IGF-I and IGFBP-5 expression are increased and contribute to stricture formation through this effect on muscle growth. To determine the signaling pathways coupling IGFBP-5 to MAPK activation and growth, smooth muscle cells were isolated from muscularis propria of human intestine and placed into primary culture. Erk1/2 and p38 MAPK activation and type I collagen production were measured by immunoblot. Proliferation was measured by [3H]thymidine incorporation. Activation of specific G proteins was measured by ELISA. AG1024, an IGF-I receptor tyrosine kinase inhibitor, was used to isolate the IGF-I-independent effects of IGFBP-5. IGFBP-5-induced phosphorylation of Erk1/2 and p38 MAPK and proliferation were abolished by pertussis toxin, implying the participation of Gi. IGFBP-5 specifically activated Gi3 but not other G proteins. Transfection of an inhibitory Gαi minigene specifically inhibited MAPK activation, proliferation, and both collagen-I and IGF-I production. Our results indicate that endogenous IGFBP-5 activates Gi3 and regulates smooth muscle growth, IGF-I production, and collagen production via the α-subunit of Gi3, independently of IGF-I, in normal human intestinal muscle cells.
The effects of apelin treatment on skeletal muscle mitochondrial content
Authors: Frier Bruce C. , Williams Deon B. , Wright David C.
Published: October 2009

Adipose tissue is recognized as a key player in the regulation of whole body metabolism. Apelin, is a recently identified adipokine that when given to mice results in increases in skeletal muscle uncoupling protein 3 (UCP3) content. Similarly, acute apelin treatment has been shown to increase the activity of 5′-AMP-activated protein kinase (AMPK), a reputed mediator of skeletal muscle mitochondrial biogenesis. Given these findings, we sought to determine the effects of apelin on skeletal muscle mitochondrial content. Male Wistar rats were given daily intraperitoneal injections of apelin-13 (100 nmol/kg) for 2 wk. We made the novel observation that the activities of citrate synthase, cytochrome c oxidase, and β-hydroxyacyl coA dehydrogenase (βHAD) were increased in triceps but not heart and soleus muscles from apelin-treated rats. When confirming these results we found that both nuclear and mitochondrial-encoded subunits of the respiratory chain were increased in triceps from apelin-treated rats. Similarly, apelin treatment increased the protein content of components of the mitochondrial import and assembly pathway. The increases in mitochondrial marker proteins were associated with increases in proliferator-activated receptor-γ coactivator-1 (PGC-1β) but not PGC-1α or Pgc-1-related co-activator (PRC) mRNA expression. Chronic and acute apelin treatment did not increase the protein content and/or phosphorylation status of AMPK and its downstream substrate acetyl-CoA carboxylase. These findings are the first to demonstrate that apelin treatment can induce skeletal muscle mitochondrial content. Given the lack of an effect of apelin on AMPK signaling and PGC-1α mRNA expression, these results suggest that apelin increases skeletal muscle mitochondrial content through a mechanism that is distinct from that of more robust physiological stressors.
Development of obesity in the Otsuka Long-Evans Tokushima Fatty rat
Authors: Schroeder Mariana , Zagoory-Sharon Orna , Shbiro Liat , Marco Asaf , Hyun Jayson , Moran Timothy H. , Bi Sheng , Weller Aron
Published: October 2009

Understanding the early factors affecting obesity development in males and females may help to prevent obesity and may lead to the discovery of more effective treatments for those already obese. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat model of obesity is characterized by hyperphagia-induced obesity, due to a spontaneous lack of CCK1receptors. In the present study, we focused on the behavioral and physiological aspects of obesity development from weaning to adulthood. We examined body weight, feeding efficiency, fat pad [brown, retroperitoneal, inguinal and epydidimal (in males)] weight, inguinal adipocyte size and number, leptin and oxytocin levels, body mass index, waist circumference, and females' estrous cycle structure. In the males, central hypothalamic gene expression was also examined. OLETF rats presented overall higher fat and leptin levels, larger adipocytes, and increased waist circumference and BMI from weaning until adulthood, compared with controls. Analysis of developmental patterns of gene expression for hypothalamic neuropeptides revealed peptide-specific patterns that may underlie or be a consequence of the obesity development. Analysis of the developmental trajectories toward obesity within the OLETF strain revealed that OLETF females developed obesity in a more gradual manner than the males, presenting delayed obesity-related “turning points,” with reduced adipocyte size but larger postweaning fat pads and increased adipocyte hyperplasia compared with the males. Intake decrease in estrus vs. proestrus was significantly less in OLETF vs. Long-Evans Tokushima Otsuka females. The findings highlight the importance of using different sex-appropriate approaches to increase the efficacy of therapeutic interventions in the treatment and prevention of chronic early-onset obesity.
Aggravated renal inflammatory responses in TRPV1 gene knockout mice subjected to DOCA-salt hypertension
Authors: Wang Youping , Wang Donna H.
Published: October 2009

To test the hypothesis that deletion of the transient receptor potential vanilloid type 1 (TRPV1) channel exaggerates hypertension-induced renal inflammatory response, wild-type (WT) or TRPV1-null mutant (TRPV1−/−) mice were subjected to uninephrectomy and deoxycorticosterone acetate (DOCA)-salt treatment for 4 wk. Mean arterial pressure (MAP) determined by radiotelemetry increased in DOCA-salt-treated WT or TRPV1−/−mice, whereas there was no difference in MAP between two strains at the baseline or after DOCA-salt treatment. DOCA-salt treatment increased urinary excretion of albumin and 8-isoprostane in both WT and TRPV1−/−mice, and the increases were greater in magnitude in the latter strain. Periodic acid-Schiff and Mason's trichrome staining showed that kidneys of DOCA-salt-treated TRPV1−/−mice exhibited more severe glomerulosclerosis and tubulointerstitial injury compared with DOCA-salt-treated WT mice. NF-κB assay showed that DOCA-salt treatment increased renal activated NF-κB concentrations in TRPV1−/−mice compared with WT mice. Immunostaining and ELISA assay revealed that DOCA-salt-treated TRPV1−/−mice had enhanced renal infiltration of monocyte/macrophage and lymphocyte, as well as increased renal levels of proinflammatory cytokine (TNF-α, IL-6) and chemokine (MCP-1) compared with DOCA-salt-treated WT mice. Renal ICAM-1 but not VCAM-1 expression was also greater in DOCA-salt-treated TRPV1−/−than WT mice. Dexamethasone (DEXA), an immunosuppressive drug, conveyed a renoprotective effect that was greater in DOCA-salt-treated TRPV1−/−compared with WT mice. These data show that renal inflammation is exacerbated in DOCA-salt hypertension when TRPV1 gene is deleted and that the deterioration is ameliorated by DEXA treatment, indicating that TRPV1 may act as a potential regulator of the inflammatory process to lessen renal injury in DOCA-salt hypertension.
Role of the kidney in the prenatal and early postnatal programming of hypertension
Authors: Baum Michel
Published: October 2009

Epidemiologic studies from several different populations have demonstrated that prenatal insults, which adversely affect fetal growth, result in an increased incidence of hypertension when the offspring reaches adulthood. It is now becoming evident that low-birth-weight infants are also at increased risk for chronic kidney disease. To determine how prenatal insults result in hypertension and chronic kidney disease, investigators have used animal models that mimic the adverse events that occur in pregnant women, such as dietary protein or total caloric deprivation, uteroplacental insufficiency, and prenatal administration of glucocorticoids. This review examines the role of the kidney in generating and maintaining an increase in blood pressure in these animal models. This review also discusses how early postnatal adverse events may have repercussions in later life. Causes for the increase in blood pressure by perinatal insults are likely multifactorial and involve a reduction in nephron number, dysregulation of the systemic and intrarenal renin-angiotensin system, increased renal sympathetic nerve activity, and increased tubular sodium transport. Understanding the mechanism for the increase in blood pressure and renal injury resulting from prenatal insults may lead to therapies that prevent hypertension and the development of chronic kidney and cardiovascular disease.
Inflammation compromises renal dopamine D1 receptor function in rats
Authors: Asghar Mohammad , Chugh Gaurav , Lokhandwala Mustafa F.
Published: October 2009

We tested the effects of inflammation on renal dopamine D1 receptor signaling cascade, a key pathway that maintains sodium homeostasis and blood pressure during increased salt intake. Inflammation was produced by administering lipopolysaccharide (LPS; 4 mg/kg ip) to rats provided without (normal salt) and with 1% NaCl in drinking water for 2 wk (high salt). Control rats had saline injection and received tap water. We found that LPS increased the levels of inflammatory cytokines, interleukin-6, and tumor necrosis factor-α in the rats given either normal- or high-salt intake. Also, these rats had higher levels of oxidative stress markers, malondialdehyde and nitrotyrosine, and lower levels of antioxidant enzyme superoxide dismutase in the renal proximal tubules (RPTs). The nuclear levels of transcription factors NF-κB increased and Nrf2 decreased in the RPTs in response to LPS in rats given normal and high salt. Furthermore, D1 receptor numbers, D1 receptor proteins, and D1 receptor agonist (SKF38393)-mediated35S-GTPγS binding decreased in the RPTs in these rats. The basal activities of Na-K-ATPase in the RPTs were similar in control and LPS-treated rats given normal and high salt. SKF38393 caused inhibition of Na-K-ATPase activity in the primary cultures of RPTs treated with vehicle but not in the cultures treated with LPS. Furthermore, LPS caused an increase in blood pressure in the rats given high salt but not in the rats given normal salt. These results suggest that LPS differentially regulates NF-κB and Nrf2, produces inflammation, decreases antioxidant enzyme, increases oxidative stress, and causes D1 receptor dysfunction in the RPTs. The LPS-induced dysfunction of renal D1 receptors alters salt handling and causes hypertension in rats during salt overload.
Influence of vibration resistance training on knee extensor and plantar flexor size, strength, and contractile speed characteristics after 60 days of bed rest
Authors: Mulder Edwin R. , Horstman Astrid M. , Stegeman Dick F. , de Haan Arnold , Belavý Daniel L. , Miokovic Tanja , Armbrecht Gabi , Felsenberg Dieter , Gerrits Karin H.
Published: October 2009

Spaceflight and bed rest (BR) result in loss of muscle mass and strength. This study evaluated the effectiveness of resistance training and vibration-augmented resistance training to preserve thigh (quadriceps femoris) and calf (triceps surae) muscle cross-sectional area (CSA), isometric maximal voluntary contraction (MVC), isometric contractile speed, and neural activation (electromyogram) during 60 days of BR. Male subjects participating in the second Berlin Bed Rest Study underwent BR only [control (CTR), n = 9], BR with resistance training (RE; n = 7), or BR with vibration-augmented resistance training (RVE; n = 7). Training was performed three times per week. Thigh CSA and MVC torque decreased by 13.5 and 21.3%, respectively, for CTR (both P < 0.001), but were preserved for RE and RVE. Calf CSA declined for all groups, but more so ( P < 0.001) for CTR (23.8%) than for RE (10.7%) and RVE (11.0%). Loss in calf MVC torque was greater ( P < 0.05) for CTR (24.9%) than for RVE (12.3%), but not different from RE (14.8%). Neural activation at MVC remained unchanged in all groups. For indexes related to rate of torque development, countermeasure subjects were pooled into one resistance training group (RT, n = 14). Thigh maximal rate of torque development (MRTD) and contractile impulse remained unaltered for CTR, but MRTD decreased 16% for RT. Calf MRTD remained unaltered for both groups, whereas contractile impulse increased across groups (28.8%), despite suppression in peak electromyogram (12.1%). In conclusion, vibration exposure did not enhance the efficacy of resistance training to preserve thigh and calf neuromuscular function during BR, although sample size issues may have played a role. The exercise regimen maintained thigh size and MVC strength, but promoted a loss in contractile speed. Whereas contractile speed improved for the calf, the exercise regimen only partially preserved calf size and MVC strength. Modification of the exercise regimen seems warranted.
Effects of heat stress on dynamic cerebral autoregulation during large fluctuations in arterial blood pressure
Authors: Brothers R. Matthew , Zhang Rong , Wingo Jonathan E. , Hubing Kimberly A. , Crandall Craig G.
Published: October 2009

Impaired cerebral autoregulation during marked reductions in arterial blood pressure may contribute to heat stress-induced orthostatic intolerance. This study tested the hypothesis that passive heat stress attenuates dynamic cerebral autoregulation during pronounced swings in arterial blood pressure. Mean arterial blood pressure (MAP) and middle cerebral artery blood velocity were continuously recorded for ∼6 min during normothermia and heat stress (core body temperature = 36.9 ± 0.1°C and 38.0 ± 0.1°C, respectively, P < 0.001) in nine healthy individuals. Swings in MAP were induced by 70-mmHg oscillatory lower body negative pressure (OLBNP) during normothermia and at a sufficient lower body negative pressure to cause similar swings in MAP during heat stress. OLBNP was applied at a very low frequency (∼0.03 Hz, i.e., 15 s on-15 s off) and a low frequency (∼0.1 Hz, i.e., 5 s on-5 s off). For each thermal condition, transfer gain, phase, and coherence function were calculated at both frequencies of OLBNP. During very low-frequency OLBNP, transfer function gain was reduced by heat stress (0.55 ± 0.20 and 0.31 ± 0.07 cm·s−1·mmHg−1during normothermia and heat stress, respectively, P = 0.02), which is reflective of improved cerebrovascular autoregulation. During low-frequency OLBNP, transfer function gain was similar between thermal conditions (1.19 ± 0.53 and 1.01 ± 0.20 cm·s−1·mmHg−1during normothermia and heat stress, respectively, P = 0.32). Estimates of phase and coherence were similar between thermal conditions at both frequencies of OLBNP. Contrary to our hypothesis, dynamic cerebral autoregulation during large swings in arterial blood pressure during very low-frequency (i.e., 0.03 Hz) OLBNP is improved during heat stress, but it is unchanged during low-frequency (i.e., 0.1 Hz) OLBNP.
Time-dependent mobilization of circulating progenitor cells during strenuous exercise in healthy individuals
Authors: Möbius-Winkler Sven , Hilberg Thomas , Menzel Kathleen , Golla Eva , Burman Agnieszka , Schuler Gerhard , Adams Volker
Published: October 2009

Exercise stimulates the release of hematopoietic and endothelial progenitor cells (EPC) from the bone marrow. However, no data are available concerning the time frame of EPC release during strenuous exercise. The aim of the present study was to investigate the time-dependent release of progenitor cells during strenuous exercise. Eighteen healthy young men cycled for 4 h continuously at 70% of their individual anaerobic threshold. Peripheral blood was drawn at 16 predefined time points during and after finishing cycling. A significant rise in heart rate and leukocytes was obvious, whereas lactate levels and hematocrit did not change. The amount of circulating progenitor cells, EPCs, mature endothelial cells (mECs), and microparticles, quantified by flow cytometry, showed a significant time-dependent increase at 210/240 min. In addition a very early rise in VEGF and later increase in IL-6, both measured by ELISA, were evident. All observed changes were normalized 24 h after finishing the test. In conclusion, strenuous activity in healthy individuals leads to a time-dependent increase in mECs, PCs, and EPCs that may be related to VEGF and IL-6.
Acid aspiration-induced airways hyperresponsiveness in mice
Authors: Allen Gilman B. , Leclair Timothy R. , von Reyn Jessica , Larrabee Yuna C. , Cloutier Mary E. , Irvin Charles G. , Bates Jason H. T.
Published: October 2009

The role of gastroesophageal reflux and micro-aspiration as a trigger of airways hyperresponsiveness (AHR) in patients with asthma is controversial. The role of acid reflux and aspiration as a direct cause of AHR in normal subjects is also unclear. We speculated that aspiration of a weak acid with a pH (1.8) equivalent to the upper range of typical gastric contents would lead to AHR in naive mice. We further speculated that modest reductions in aspirate acidity to a level expected during gastric acid suppression therapy (pH 4.0) would impede aspiration-induced AHR. BALB/c female mice were briefly anesthetized with isoflurane and allowed to aspirate 75 μl of saline with HCl (pH 1.8, 4.0, or 7.4) or underwent sham aspiration. Mice were re-anesthetized 2 or 24 h later, underwent tracheostomy, and were coupled to a mechanical ventilator. Forced oscillations were used to periodically measure respiratory impedance (Zrs) following aerosol delivery of saline and increasing doses of methacholine to measure for AHR. Values for elastance ( H), airways resistance (RN), and tissue damping ( G) were derived from Zrs. Aspirate pH of 1.8 led to a significant overall increase in peak RN, G, and H compared with pH 4.0 and 7.4 at 2 and 24 h. Differences between pH 7.4 and 4.0 were not significant. In mice aspirating pH 1.8 compared with controls, airway lavage fluid contained more neutrophils, higher protein, and demonstrated higher permeability. We conclude that acid aspiration triggers an acute AHR, driven principally by breakdown of epithelial barrier integrity within the airways.
Muscle interstitial ATP and norepinephrine concentrations in the human leg during exercise and ATP infusion
Authors: Mortensen Stefan P. , González-Alonso José , Nielsen Jens-Jung , Saltin Bengt , Hellsten Ylva
Published: October 2009

ATP has been proposed to play multiple roles in local skeletal muscle blood flow regulation by inducing vasodilation and modulating sympathetic vasoconstrictor activity, but the mechanisms remain unclear. Here we evaluated the effects of arterial ATP infusion and exercise on leg muscle interstitial ATP and norepinephrine (NE) concentrations to gain insight into the interstitial and intravascular mechanisms by which ATP causes muscle vasodilation and sympatholysis. Leg hemodynamics and muscle interstitial nucleotide and NE concentrations were measured during 1) femoral arterial ATP infusion (0.42 ± 0.04 and 2.26 ± 0.52 μmol/min; mean ± SE) and 2) one-leg knee-extensor exercise (18 ± 0 and 37 ± 2 W) in 10 healthy men. Arterial ATP infusion and exercise increased leg blood flow (LBF) in the experimental leg from ∼0.3 l/min at baseline to 4.2 ± 0.3 and 4.6 ± 0.5 l/min, respectively, whereas it was reduced or unchanged in the control leg. During arterial ATP infusion, muscle interstitial ATP, ADP, AMP, and adenosine concentrations remained unchanged in both legs, but muscle interstitial NE increased from ∼5.9 nmol/l at baseline to 8.3 ± 1.2 and 8.7 ± 0.7 nmol/l in the experimental and control leg, respectively ( P < 0.05), in parallel to a reduction in arterial pressure ( P < 0.05). During exercise, however, interstitial ATP, ADP, AMP, and adenosine concentrations increased in the contracting muscle ( P < 0.05), but not in inactive muscle, whereas interstitial NE concentrations increased similarly in both active and inactive muscles. These results suggest that the vasodilatory and sympatholytic effects of intraluminal ATP are mainly mediated via endothelial purinergic receptors. Intraluminal ATP and muscle contractions appear to modulate sympathetic nerve activity by inhibiting the effect of NE rather than blunting its local concentration.
Noninvasive real-time measurement of nasal mucociliary clearance in mice by pinhole gamma scintigraphy
Authors: Hua Xiaoyang , Zeman Kirby L. , Zhou Bingqing , Hua Qingquan , Senior Brent A. , Tilley Stephen L. , Bennett William D.
Published: October 2009

Mucociliary clearance (MCC) is the key defense mechanism in the upper airways, as the removal of debris-laden mucus in the sinuses completely depends on MCC. So far, how the nasal MCC is regulated remains unknown. Recently, mice deficient in genes encoding the components of MCC apparatus have been generated, which will allow investigators to conduct more in-depth nasal MCC studies. However, the methodology necessary to comprehensively evaluate the nasal MCC in this species is not well established. We therefore developed a novel method to measure nasal MCC in live mice using pinhole gamma camera. Insoluble radiolabeled particles were delivered into the noses of lightly anesthetized mice. The nasal clearance of these particles was measured continuously in a real-time manner. The effect of three different anesthetics—avertin, pentobarbital, and isoflurane—on nasal MCC was also determined. In mice anesthetized by 1.1% isoflurane, radiolabeled particles were immediately moved into the oropharynx, which was significantly accelerated by the treatment of hypertonic but not isotonic saline. According to the clearance rate, the mouse nasal MCC presented two distinct phases: a rapid phase and a slow phase. In addition, we found that isoflurane had a very small inhibitory effect on nasal MCC vs. both avertin and pentobarbital. This was further supported by its dose response. Collectively, we have developed a noninvasive method to monitor the real-time nasal MCC in live mice under physiological conditions. It provides more comprehensive evaluation on nasal MCC rather than assessing a single component of the MCC apparatus in isolation.
Processing of Visual Signals for Direct Specification of Motor Targets and for Conceptual Representation of Action Targets in the Dorsal and Ventral Premotor Cortex
Authors: Yamagata Tomoko , Nakayama Yoshihisa , Tanji Jun , Hoshi Eiji
Published: October 2009

Previous reports have indicated that the premotor cortex (PM) uses visual information for either direct guidance of limb movements or indirect specification of action targets at a conceptual level. We explored how visual inputs signaling these two different categories of information are processed by PM neurons. Monkeys performed a delayed reaching task after receiving two different sets of visual instructions, one directly specifying the spatial location of a motor target (a direct spatial-target cue) and the other providing abstract information about the spatial location of a motor target by indicating whether to select the right or left target at a conceptual level (a symbolic action-selection cue). By comparing visual responses of PM neurons to the two sets of visual cues, we found that the conceptual action plan indicated by the symbolic action-selection cue was represented predominantly in dorsal PM (PMd) neurons with a longer latency (150 ms), whereas both PMd and ventral PM (PMv) neurons responded with a shorter latency (90 ms) when the motor target was directly specified with the direct spatial-target cue. We also found that excited, but not inhibited, responses of PM neurons to the direct spatial-target cue were biased toward contralateral preference. In contrast, responses to the symbolic action-selection cue were either excited or inhibited without laterality preference. Taken together, these results suggest that the PM constitutes a pair of distinct circuits for visually guided motor act; one circuit, linked more strongly with PMd, carries information for retrieving action instruction associated with a symbolic cue, and the other circuit, linked with PMd and PMv, carries information for directly specifying a visuospatial position of a reach target.
Structural and Ultrastructural Analysis of Cerebral Cortex, Cerebellum, and Hypothalamus from Diabetic Rats
Authors: Hernández-Fonseca Juan P. , Rincón Jaimar , Pedreañez Adriana , Viera Ninoska , Arcaya José L. , Carrizo Edgardo , Mosquera Jesús
Published: October 2009

Autonomic and peripheral neuropathies are well-described complications in diabetes. Diabetes mellitus is also associated to central nervous system damage. This little-known complication is characterized by impairment of brain functions and electrophysiological changes associated with neurochemical and structural abnormalities. The purpose of this study was to investigate brain structural and ultrastructural changes in rats with streptozotocin-induced diabetes. Cerebral cortex, hypothalamus, and cerebellum were obtained from controls and 8 weeks diabetic rats. Light and electron microscope studies showed degenerative changes of neurons and glia, perivascular and mitochondrial swelling, disarrangement of myelin sheath, increased area of myelinated axons, presynaptic vesicle dispersion in swollen axonal boutoms, fragmentation of neurofilaments, and oligodendrocyte abnormalities. In addition, depressive mood was observed in diabetic animals. The brain morphological alterations observed in diabetic animals could be related to brain pathologic process leading to abnormal function, cellular death, and depressive behavioral.