bluuebunny/crossref_metadata_2025 huggingface dataset:
Fertilization dynamics of sperm from different male mating tactics in bluegill (Lepomis macrochirus)
Authors: Schulte-Hostedde Albrecht I , Burness Gary
Published: January 2006

Sperm competition results in the evolution of ejaculate characteristics such as high sperm density, high motility, and fast sperm swimming speed. A fundamental assumption of sperm competition theory is that ejaculates with high motility and fast-swimming sperm have an advantage with respect to fertilization success. We tested this assumption by studying the fertilization dynamics of alternative mating tactics (cuckolders and parentals) of male bluegill (Lepomis macrochirus Rafinesque, 1819). Sneakers (cuckolders) have faster swimming sperm and a higher proportion of motile sperm immediately following sperm activation than do parentals; however, these variables decline more quickly over time in sneaker sperm than in the sperm of parental males. We used a controlled fertilization experiment to test the prediction that parental males will have higher fertilization success than sneakers late in the sperm activation cycle because of the reduced rate of decline in ejaculate quality over time. We found that as the time from sperm activation increases parental sperm fertilizes more eggs than the sperm of sneakers. Our results support the idea that fertilization success is higher when ejaculates contain a higher proportion of either motile sperm or faster swimming sperm, all else being equal. In addition, after controlling for time from sperm activation, we found a significant bias in fertilization success toward parental males, suggesting that cryptic female choice might play a role in fertilization dynamics.
ON THE COMPLEX GINZBURG–LANDAU EQUATION WITH A DELAYED FEEDBACK
Authors: CASAL A. C. , DÍAZ J. I.
Published: January 2006

We show how to stabilize the uniform oscillations of the complex Ginzburg–Landau equation with periodic boundary conditions by means of some global delayed feedback. The proof is based on an abstract pseudo-linearization principle and a careful study of the spectrum of the linearized operator.
GLOBAL SOLUTIONS FOR THE ONE-DIMENSIONAL VLASOV–MAXWELL SYSTEM FOR LASER-PLASMA INTERACTION
Authors: CARRILLO JOSÉ A. , LABRUNIE SIMON
Published: January 2006

We analyze a reduced 1D Vlasov–Maxwell system introduced recently in the physical literature for studying laser-plasma interaction. This system can be seen as a standard Vlasov equation in which the field is split into two terms: an electrostatic field obtained from Poisson's equation and a vector potential term satisfying a nonlinear wave equation. Both nonlinearities in the Poisson and wave equations are due to the coupling with the Vlasov equation through the charge density. We show global existence of weak solutions in the nonrelativistic case, and global existence of characteristic solutions in the quasi-relativistic case. Moreover, these solutions are uniquely characterized as fixed points of a certain operator. We also find a global energy functional for the system allowing us to obtain Lp-nonlinear stability of some particular equilibria in the periodic setting.
ON BOUNDARY PERMEATION IN NAVIER–STOKES AND SECOND GRADE INCOMPRESSIBLE FLUIDS
Authors: MARITZ RIËTTE , SAUER NIKO
Published: January 2006

A mathematical model for the phenomenon of penetration of fluid into permeable walls is developed for second grade fluids. The model is based on mechanical principles which involve normal stresses at the boundary and contact forces at the fluid-boundary interface. Stability of the rest state is proved. The results are compared to that for the simplified case of a Navier–Stokes fluid.
DISCONTINUOUS FINITE ELEMENT APPROXIMATION OF QUASISTATIC CRACK GROWTH IN NONLINEAR ELASTICITY
Authors: GIACOMINI ALESSANDRO , PONSIGLIONE MARCELLO
Published: January 2006

We propose a time-space discretization of a general notion of quasistatic growth of brittle fractures in elastic bodies proposed by Dal Maso, Francfort and Toader,14 which takes into account body forces and surface loads. We employ adaptive triangulations and prove convergence results for the total, elastic and surface energies. In the case in which the elastic energy is strictly convex, we also prove a convergence result for the deformations.
CONSERVATION LAWS FOR ONE-DIMENSIONAL SHALLOW WATER MODELS FOR ONE AND TWO-LAYER FLOWS
Authors: BARROS RICARDO
Published: January 2006

A full set of conservation laws for the two-layer shallow water equations is presented for the one-dimensional case. We prove that all the conservation laws are linear combination of the equations for the conservation of mass and velocity (in each layer), total momentum and total energy.This result generalizes that of Montgomery and Moodie that found the same conserved quantities by restricting their search to the multinomials expressions in the layer variables. Though the question of whether or not there are only a finite number of these quantities is left as an open question by the authors. Our work puts an end to this: in fact, no more conservation laws are admitted for the two-layer shallow water equations. The key mathematical ingredient of the method proposed leading to the result is the Frobenius problem. Moreover, we present a full set of conservation laws for the classical one-dimensional shallow water model with topography, by using the same techniques.
SHARP REGULARITY COEFFICIENT ESTIMATES FOR COMPLEX-VALUED ACOUSTIC AND ELASTIC HELMHOLTZ EQUATIONS
Authors: CUMMINGS PETER , FENG XIAOBING
Published: January 2006

We consider complex-valued acoustic and elastic Helmholtz equations with the first order absorbing boundary condition in a star-shaped domain in ℜN for N ≥ 2. It is known that the elliptic regularity coefficients depend on the frequency ω, and have singularities for both zero and infinite frequency. In this paper, we obtain sharp estimates for the coefficients with respect to large frequencies. It is proved that the elliptic regularity coefficients are bounded by first or second order polynomials in ω for large ω. The crux of our analysis is to establish and make use of Rellich identities for the solutions to the acoustic and elastic Helmholtz equations. Our results improve the earlier estimates of Refs. 10 and 11, which were carried out based on layer potential representations of the solutions of the Helmholtz equations.
Designing a New Class of Fault Tolerant Multistage Interconnection Networks
Authors: Arya K. V. , Ghosh R. K.
Published: January 2006

This paper proposes a technique to modify a Multistage Interconnection Network (MIN) to augment it with fault tolerant capabilities. The augmented MIN is referred to as Enhanced MIN (E-MIN). The technique employed for construction of E-MIN is compared with the two known physical fault tolerance techniques, namely, extra staging and chaining. EMINs are found to be more generic than extra staged networks and less expensive than chained networks. The EMIN realizes all the permutations realizable by the original MIN. The routing strategies under faulty and fault free conditions are shown to be very simple in the case of E-MINs.
WAVELENGTH ASSIGNMENT IN MULTIFIBER OPTICAL STAR NETWORKS UNDER THE MULTICASTING COMMUNICATION MODE
Authors: BRANDT RUSSELL , GONZALEZ TEOFILO F.
Published: January 2006

This paper examines the wavelength assignment problem for single, dual, and multimessage multicasting over a star network with optical switching between fibers along the same wavelength. The specific problem we consider is given any star network, a predetermined number of fibers that connect its nodes, and a set of multicasts (or multidestination messages) to be delivered in one communication round, find a conflict free message transmission schedule that uses the least number of wavelengths per fiber. When the least number of wavelengths, λmin, exceeds the number available, λavl, one may transform the schedule into one with ⌈λmin/λavl⌉ communication phases or rounds over the same network, but restricted to λavl wavelengths per fiber.
1-Vertex-Hamiltonian-Laceability of Hypercubes with Maximal Edge Faults
Authors: Hsieh Sun-Yuan , Kuo Che-Nan
Published: January 2006

Suppose that G = (V0 ∪ V1, E) is a bipartite graph with two partite sets V0 and V1 of equal size. Let x and y be two arbitrary distinct, vertices and let w be another vertex different from x and y. G is said to be 1-vertex-Hamiltonian-laceable if G - w satisfies the following three properties:

P1. There is a (|V0| + |V1| - 2)-length path between x and y, where x and y are in the same partite set and w is in the other partite set;

P2. There is a (|V0| + |V1| - 3)-length path between x and y, where x and y are in different partite sets and w is in any partite set;

P3. There is a (|V0| + |V1| - 4)-length path between x and y, where x, y, w are in the same partite set.

Let Fe be the set of faulty edges of an n-dimensional hypercube Qn. In this paper, we show that Qn - Fe (the graph obtained by deleting all edges of Fe from Qn) remains 1-vertex-Hamiltonian-laceable when |Fe| ≤ n - 3.
Efficient Algorithms for Some Common Applications on GHCC
Authors: Mukhopadhyaya Srabani , Sinha Bhabani P.
Published: January 2006

Generalized Hypercube-Connected-Cycles (GHCC), is a challenging interconnection network, proposed earlier in the literature. In this paper, we discuss how some important, useful algorithms, like, matrix transpose, matrix multiplication and sorting can efficiently be implemented on GHCC. Matrix transpose and matrix-by-matrix multiplication of matrices of order n × n, [Formula: see text], takes O(l) and [Formula: see text] time, respectively, on GHCC(l,m), with lml processors. Using the same number of processors, a list of ml numbers can be sorted in O(l2 log 3 m) time.
SOFTWARE SUPPORTS FOR EVENT PREEMPTIVE ROLLBACK IN OPTIMISTIC PARALLEL SIMULATION ON MYRINET CLUSTERS
Authors: SANTORO ANDREA , QUAGLIA FRANCESCO
Published: January 2006

Optimistic synchronization protocols for parallel discrete event simulation employ rollback techniques to ensure causally consistent execution of simulation events. Although event preemptive rollback (i.e. rollback based on timely event execution interruption upon the arrival of a message revealing a causality inconsistency) is recognized as an approach for increasing the performance and tackling run-time anomalies of this type of synchronization, the lack of adequate functionalities at the level of general purpose communication layers typically prevents any effective implementation of event preemptive rollback operations. In this paper we present the design and implementation of a communication layer for Myrinet based clusters, which efficiently supports event preemptive rollback operations. Beyond standard low latency message delivery funcbionalities, this layer also embeds functionalities for allowing the overlying simulation application to efficiently track whether a message will actually produce causality inconsistency of the currently executed simulation event upon its receipt at the application level. Exploiting these functionalities, awareness of the inconsistency precedes the message receipt at the application level, thus allowing timely event execution interruption for activating rollback procedures. We also report experimental results demonstrating the effectiveness of our solution for a Personal Communication System (PCS) simulation application.
EFFECT OF VISCOUS LIQUID FILM ON DYNAMIC CONTACT IN ATOMIC FORCE MICROSCOPY
Authors: YANG FUQIAN
Published: January 2006

This letter incorporates squeezing flow with the Hertz contact theory in analyzing the dynamic behavior of an AFM tip in contact with an elastic substrate and a liquid film. To the first order of approximation, a new dynamic equation describing the motion of the AFM tip is presented, from which closed-form solutions of the stored contact modulus and loss contact modulus are obtained. The results show that the stored contact modulus depends on the frequency of the oscillation, the elastic properties of the elastic material and the mass of the tip, while it is independent of the viscosity of the liquid film. These provide a theoretical basis for the characterization of the elastic properties of biological materials and nanostructures by using the technique of continuous stiffness measurement.
GLOBAL PROPERTIES OF BIOMIMETIC MEMBRANES: PERSPECTIVES ON MOLECULAR FEATURES
Authors: PABST GEORG
Published: January 2006

Global properties of biological model membranes such as, e.g., structure or elasticity, are known to be closely related to their local features. If a membrane active compound interacts with the membrane assembly, the membrane will primarily be affected on the local, molecular level. The local perturbation may than, through some coupling, translate into a global adjustment of the membrane. In order to address this coupling x-ray and neutron diffraction data analysis techniques have been developed that allow accurate monitoring of changes in global properties. This offers new perspectives on molecular membrane features that in combination with complementary techniques, such as differential scanning calorimetry, spectroscopy or dynamic scattering lead to a better understanding of biomimetic membranes. The present article reviews these aspects giving application examples for single- and multicomponent membranes, respectively.
FOLDING AND STRUCTURAL CHARACTERIZATION OF RECOMBINANT CYCLIN-DEPENDENT KINASE INHIBITOR p21(Cip1, Waf1, Sdi1)
Authors: CHANG CHIA-CHING , LIN CHIU-SHEUN , CHEN MEI-CHUN , LIU YIN-CHANG , HUANG YI-FU , LIN PO-YEN , CHEN YEN-FU , CHANG CHIA-SHENG , KAN LOU-SING
Published: January 2006

p21Cip1, Waf1, Sdi1 (p21) is a member of the cyclin-dependent kinase (CDK) family of inhibitors in eukaryotes. We report the refolding of an inclusion body of a recombinant p21 (rp21) to its native form, under an alkaline to neutral environment, via an over-critical process describable by a first-order state transition model. The secondary structure of the refolded rp21 possesses a helical-major structure as determined by circular dichroism (CD) analysis, and its diameter is around 3 nm, as measured by dynamic light scattering studies (DLS) and atomic force microscopy (AFM). The differential scanning calorimeter (DSC) measurement indicates that the folded rp21 possesses unique but weak tertiary interactions. That the function of rp21 is reinstated upon refolding under our experimental conditions is evidenced by its binding to proliferating cell nuclear antigen (PCNA) in an immuno-co-precitptation analysis. The conformational changes of the folding intermediates of rp21 are consistent with the framework of a sequential model proposed earlier. The lack of a definitive structure of p21 in acidic condition will be discussed.
DYNAMICS OF VESICLE ADHESION: SPREADING VERSUS DEWETTING COUPLED TO BINDER DIFFUSION
Authors: PUECH P.-H. , ASKOVIC V. , DE GENNES P.-G. , BROCHARD-WYART F.
Published: January 2006

We study the kinetics of specific adhesion of giant vesicles on complemetary (bilayer-decorated) solid surfaces. Tensed vesicles exhibit a single adhesion zone that grows slowly. Floppy vesicles adhere via many small adhesion spots that grow and fuse, merging finally into a large adhesive zone. Using approaches derived from Ref. 12, we show how the progressive mobilization of adhesive molecules (diffusing toward the patch) can explain our experimental observations.
Structural morphology of renal vasculature
Authors: Nordsletten David A. , Blackett Shane , Bentley Michael D. , Ritman Erik L. , Smith Nicolas P.
Published: January 2006

An automatic segmentation technique has been developed and applied to two renal micro-computer tomography (CT) images. With the use of a 20-μm voxel resolution image, the arterial and venous trees were segmented for the rat renal vasculature, distinguishing resolving vessels down to 30 μm in radius. A higher resolution 4-μm voxel image of a renal vascular subtree, with vessel radial values down to 10 μm, was segmented. Strahler ordering was applied to each subtree using an iterative scheme developed to integrate information from the two segmented models to reconstruct the complete topology of the entire vascular tree. An error analysis of the assigned orders quantified the robustness of the ordering process for the full model. Radial, length, and connectivity data of the complete arterial and venous trees are reported by order. Substantial parallelism is observed between individual arteries and veins, and the ratio of parallel vessel radii is quantified via a power law. A strong correlation with Murray's Law was established, providing convincing evidence of the “minimum work” hypothesis. Results were compared with theoretical branch angle formulations, based on the principles of “minimum shear force,” were inconclusive. Three-dimensional reconstructions of renal vascular trees collected are made freely available 1 1 http://www.physiome.org.nz/publications/nordsletten_blackett_ritman_bentley_smith_2005 . for further investigation into renal physiology and modeling studies.
New near-infrared optical probes of cardiac electrical activity
Authors: Matiukas Arvydas , Mitrea Bogdan G. , Pertsov Arkady M. , Wuskell Joseph P. , Wei Mei-de , Watras James , Millard Andrew C. , Loew Leslie M.
Published: January 2006

Styryl voltage-sensitive dyes (e.g., di-4-ANEPPS) have been widely and successfully used as probes for mapping membrane potential changes in cardiac cells and tissues. However, their utility has been somewhat limited because their excitation wavelengths have been restricted to the 450- to 550-nm range. Longer excitation/emission wavelength probes can minimize interference from endogenous chromophores and, because of decreased light scattering and lower absorption by endogenous chromophores, improve recording from deeper tissue layers. In this article, we report efforts to develop new potentiometric styryl dyes that have excitation wavelengths ranging above 700 nm and emission spectra extending to 900 nm. Three dyes for cardiac optical mapping were investigated in depth from several hundred dyes containing 47 variants of the styryl chromophores. Absorbance and emission spectra in ethanol and multilamellar vesicles, as well as voltage-dependent spectral changes in a model lipid bilayer, have been recorded for these dyes. Optical action potentials were recorded in typical cardiac tissues (rat, guinea pig, pig) and compared with those of di-4-ANEPPS. The voltage sensitivities of the fluorescence of these new potentiometric indicators are as good as those of the widely used ANEP series of probes. In addition, because of molecular engineering of the chromophore, the new dyes provide a wide range of dye loading and washout time constants. These dyes will enable a series of new experiments requiring the optical probing of thick and/or blood-perfused cardiac tissues.
Evidence for histamine as a neurotransmitter in the cardiac sympathetic nervous system
Authors: Li Mingkai , Hu Jing , Chen Zhong , Meng Jia , Wang Haifang , Ma Xue , Luo Xiaoxing
Published: January 2006

The colocalization of histamine (HA) and norepinephrine (NE) immunoreactivities was identified within the superior cervical ganglia neurons of the guinea pig. HA and NE immunoreactivity levels were significantly attenuated after chemical sympathectomy with 6-hydroxydopamine (6-OHDA). Coexistence of NE and HA was also visualized in the cardiac sympathetic axon and varicosities labeled with anterograde tracer biotinylated dextran amine. Depolarization of cardiac sympathetic nerve endings (synaptosomes) with 50 mM potassium stimulated endogenous HA release, which was significantly attenuated by 6-OHDA or a vesicular monoamine transporter 2 (VMAT2) inhibitor reserpine pretreatments. Compound 48/80, a mast cell releaser, did not affect cardiac synaptosome HA exocytosis. Furthermore, K+-evoked HA release was abolished by the N-type Ca2+-channel blocker ω-conotoxin but was not affected by the L-type Ca2+-channel blocker lacidipine. Cardiac synaptosome HA exocytosis was augmented by the enhanced synthesis of HA or the inhibition of HA metabolism. HA H3-receptor activation by ( R)-α-methylhistamine inhibited high K+-evoked histamine release. The HA H3receptor antagonist thioperamide enhanced K+-evoked HA release and blocked the ( R)-α-methylhistamine effect. The K+-evoked endogenous NE release was attenuated by preloading the cardiac synaptosomes with l-histidine or quinacrine. These inhibitory effects were reversed by thioperamide or antagonized by α-fluoromethylhistidine. Our findings indicate that high K+-evoked corelease of NE and HA may be inhibited by endogenous HA via activation of presynaptic HA H3-receptors. The H3-receptor may function as an autoreceptor, rather than a heteroreceptor, in the regulation of sympathetic neurotransmission and HA may be a novel sympathetic neurotransmitter.
Detection of sequence-specific tyrosine nitration of manganese SOD and SERCA in cardiovascular disease and aging
Authors: Xu Shanqin , Ying Jia , Jiang Bingbing , Guo Wei , Adachi Takeshi , Sharov Viktor , Lazar Harold , Menzoian James , Knyushko Tatyana V. , Bigelow Diana , Schöneich Christian , Cohen Richard A.
Published: January 2006

Nitration of protein tyrosine residues (nY) is a marker of oxidative stress and may alter the biological activity of the modified proteins. The aim of this study was to develop antibodies toward site-specific nY-modified proteins and to use histochemistry and immunoblotting to demonstrate protein nitration in tissues. Affinity-purified polyclonal antibodies toward peptides with known nY sites in MnSOD nY-34 and of two adjacent nY in the sarcoplasmic endoplasmic reticulum calcium ATPase (SERCA2 di-nY-294,295) were developed. Kidneys from rats infused with ANG II with known MnSOD nY and aorta from atherosclerotic rabbits and aging rat skeletal and cardiac sarcoplasmic reticulum with known SERCA di-nY were used for positive controls. Staining for MnSOD nY-34 was most intense in distal renal tubules and collecting ducts. Staining of atherosclerotic aorta for SERCA2 di-nY was most intense in atherosclerotic plaques. Aging rat skeletal muscle and atherosclerotic aorta and cardiac atrium from human diabetic patients also stained positively. Staining was decreased by sodium dithionite, which chemically reduces nitrotyrosine to aminotyrosine, and the antigenic nY-peptide blocked staining for each respective nY site but not for the other. As previously demonstrated, immunoblotting failed to detect these modified proteins in whole tissue lysates but did when the proteins were concentrated. Immunohistochemical staining for specific nY-modified tyrosine residues offers the ability to assess the effects of oxidant stress associated with pathological conditions on individual proteins whose function may be affected in specific tissue sites.
Metabolic indicators in the skeletal muscles of harbor seals (Phoca vitulina)
Authors: Polasek L. K. , Dickson K. A. , Davis R. W.
Published: January 2006

The goal of this study was to determine the distribution of citrate synthase (CS), β-hydroxyacyl coenzyme A dehydrogenase (HOAD), and lactate dehydrogenase (LDH) activities and myoglobin (Mb) concentration in the locomotor muscles (epaxial muscles) and heart of harbor seals. The entire epaxial musculature, which produces most of the power for submerged swimming, was removed and weighed, and three transverse sections (cranial, middle, and caudal) were taken along the muscle bundle. Multiple samples were taken along points on a circular grid using a 6-mm biopsy. A single sample was taken from the left ventricle of the heart. Muscle groups of similar function were taken from three dogs as a control. Mean values were calculated for four roughly equal quadrants in each transverse section of the epaxial muscles. There were no significant differences among the quadrants within any of the transverse sections for the three enzymes or Mb. However, there were significant differences in the mean enzyme activities and Mb concentrations along the length of the muscle. The middle and caudal sections had significantly higher mean levels of CS, LDH, and Mb than the cranial section, which may be correlated with power production during swimming. The enzyme ratios CS/HOAD and LDH/CS exhibited no variation within transverse sections or along the length of the epaxial muscles. Relative to the dog, the epaxial muscles and heart of the harbor seal had higher HOAD levels and lower CS/HOAD, which, taken together, indicate an increased capacity for aerobic lipid metabolism during diving.
Restitution of single-cell defects in the mouse colon epithelium differs from that of cultured cells
Authors: Günzel D. , Florian P. , Richter J. F. , Troeger H. , Schulzke J. D. , Fromm M. , Gitter A. H.
Published: January 2006

Integrity of colon epithelium is of crucial importance and, as small defects occur constantly, rapid repair (restitution) is essential. To investigate the mechanism of restitution, single-cell lesions were induced in mouse colonic surface epithelia by iontophoretic injection of Ca2+. Closure of the resulting defects was monitored using confocal laser scanning microscopy (CLSM), and functional sealing by electrophysiological techniques. Restitution was evaluated as the time constant τ of the exponential decrease in conductance of an induced leak and amounted to 0.28 min under control conditions. After 4 min, the leak was completely sealed. Repair was thus considerably faster than in previously investigated HT-29/B6 cells (τ = 5.73 min). As in cultured cells, cytochalasin D delayed restitution in native colon epithelia (τ = 0.69 min), indicating the involvement of actin in the healing process; however, no accumulation of actin surrounding the lesion was detected. Long-term incubation of epithelia with IFN-γ alone or in combination with TNF-α increased τ to 0.49 and 0.59 min, respectively. In contrast to cultured cells, TNF-α alone did not affect restitution. A brief (<10 min) exposure to the sterile filtered supernatant of hemolytic E. coli O4 cultures did not affect the morphology of the epithelium, but delayed restitution. In CLSM studies, defects were still clearly visible 4 min after the onset of lesion induction. The supernatant of a nonhemolytic E. coli O4 mutant did not exhibit this effect. In conclusion, single-cell defects in native colon cause functional leaks that seal faster than in cell cultures. Proinflammatory cytokines and pathogenic bacteria delay restitution. This suggests a key role of very small lesions at the onset of pathogenic processes in the intestine.
Prenatal exposure to dexamethasone alters hippocampal drive on hypothalamic-pituitary-adrenal axis activity in adult male rats
Authors: Shoener Jennifer A. , Baig Romana , Page Kathleen C.
Published: January 2006

Glucocorticoids are essential for normal hypothalamic-pituitary-adrenal (HPA) axis activity; however, recent studies warn that exposure to excess endogenous or synthetic glucocorticoid during a specific period of prenatal development adversely affects HPA axis stability. We administered dexamethasone (DEX) to pregnant rats during the last week of gestation and investigated subsequent HPA axis regulation in adult male offspring in unrestrained and restraint-stressed conditions. With the use of real-time PCR and RIA, we examined the expression of regulatory genes in the hippocampus, hypothalamus, and pituitary, including corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), glucocorticoid receptors (GR), mineralcorticoid receptors (MR), and 11-β-hydroxysteroid dehydrogenase-1 (11β-HSD-1), as well as the main HPA axis hormones, adrenal corticotropic hormone (ACTH) and corticosterone (CORT). Our results demonstrate that the DEX-exposed group exhibited an overall change in the pattern of gene expression and hormone levels in the unrestrained animals. These changes included an upregulation of CRH in the hypothalamus, a downregulation of MR with a concomitant upregulation of 11β-HSD-1 in the hippocampus, and an increase in circulating levels of both ACTH and CORT relative to unrestrained control animals. Interestingly, both DEX-exposed and control rats exhibited an increase in pituitary GR mRNA levels following a 1-h recovery from restraint stress; however, the increased expression in DEX-exposed rats was significantly less and was associated with a slower return to baseline CORT compared with controls. In addition, circulating levels of ACTH and CORT as well as hypothalamic CRH and hippocampal 11β-HSD-1 expression levels were significantly higher in the DEX-exposed group compared with controls following restraint stress. Taken together, these data demonstrate that late-gestation DEX exposure in rats is associated with persistent changes in both the modulation of HPA axis activity and the HPA axis-mediated response to stress.
Characterization of blood pressure and renal function in chromosome 5 congenic strains of Dahl S rats
Authors: Roman Richard J. , Hoagland Kimberly M. , Lopez Bernardo , Kwitek Anne E. , Garrett Michael R. , Rapp John P. , Lazar Josef , Jacob Howard J. , Sarkis Albert
Published: January 2006

The present study examined whether transfer of overlapping regions of chromosome 5 that include (4A+) or exclude the cytochrome P-450 (CYP) 4A genes from the Lewis rat alters the renal production of 20-hydroxyeicosatetraenoic acid (20-HETE) and/or the development of hypertension in congenic strains of Dahl salt-sensitive (S) rats. The expression of CYP4A protein and the production of 20-HETE in the renal outer medulla was greater in the 4A+congenic strain than the levels seen in S rats or in overlapping control congenic strains that exclude the CYP4A region. Mean arterial pressure (MAP) rose from 122 ± 2 to 190 ± 7 mmHg in S rats and from 119 ± 2 and 123 ± 2 to 189 ± 7 and 187 ± 3 mmHg in the two control congenic strains fed an 8.0% NaCl diet for 3 wk. In contrast, MAP only increased from 112 ± 2 to 150 ± 5 mmHg in the 4A+congenic strain. Chronic blockade of the formation of 20-HETE with N-(3-chloro-4-morpholin-4-yl) phenyl- N′-hydroxyimido formamide (TS-011; 1 mg/kg bid) restored the salt-sensitive phenotype in the 4A+congenic strain and MAP rose to 181 ± 6 mmHg after an 8.0% NaCl dietary challenge. TS-011 had no effect on the development of hypertension in S rats or the two control congenic strains. The pressure-natriuretic and diuretic responses were fivefold greater in the 4A+congenic strain than in S rats. These results indicate that transfer of the region of chromosome 5 between markers D5Rat108 to D5Rat31 from the Lewis rat into the Dahl S genetic background increases the renal production of 20-HETE, improves pressure-natriuresis and opposes the development of salt-induced hypertension.
Genetic AVP deficiency abolishes cold-induced diuresis but does not attenuate cold-induced hypertension
Authors: Sun Zhongjie
Published: January 2006

Chronic cold exposure causes hypertension and diuresis. The aim of this study was to determine whether vasopressin (AVP) plays a role in cold-induced hypertension and diuresis. Two groups of Long-Evans (LE) and two groups of homozygous AVP-deficient Brattleboro (VD) rats were used. Blood pressure (BP) was not different among the four groups during a 2-wk control period at room temperature (25°C, warm). After the control period, one LE group and one VD group were exposed to cold (5°C); the remaining groups were kept at room temperature. BP and body weight were measured weekly during exposure to cold. Food intake, water intake, urine output, and urine osmolality were measured during weeks 1, 3, and 5 of cold exposure. At the end of week 5, all animals were killed and blood was collected for measurement of plasma AVP. Kidneys were removed for measurement of renal medulla V2receptor mRNA and aquaporin-2 (AQP-2) protein expression. BP of LE and VD rats increased significantly by week 2 of cold exposure and reached a high level by week 5. BP elevations developed at approximately the same rate and to the same degree in LE and VD rats. AVP deficiency significantly increased urine output and solute-free water clearance and decreased urine osmolality. Chronic cold exposure increased urine output and solute-free water clearance and decreased urine osmolality in LE rats, indicating that cold exposure caused diuresis in LE rats. Cold exposure failed to affect these parameters in VD rats, suggesting that the AVP system is responsible for cold-induced diuresis. Cold exposure did not alter plasma AVP in LE rats. Renal medulla V2receptor mRNA and AQP-2 protein expression levels were decreased significantly in the cold-exposed LE rats, suggesting that cold exposure inhibited renal V2receptors and AVP-inducible AQP-2 water channels. We conclude that 1) AVP may not be involved in the pathogenesis of cold-induced hypertension, 2) the AVP system plays a critical role in cold-induced diuresis, and 3) cold-induced diuresis is due to suppression of renal V2receptors and the associated AQP-2 water channels, rather than inhibition of AVP release.
Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells
Authors: Siroky Brian J. , Ferguson William B. , Fuson Amanda L. , Xie Yi , Fintha Attila , Komlosi Peter , Yoder Bradley K. , Schwiebert Erik M. , Guay-Woodford Lisa M. , Bell P. Darwin
Published: January 2006

Recent genetic analysis has identified a pivotal role of primary cilia in the pathogenesis of polycystic kidney disease (PKD). However, little is known regarding how cilia loss/dysfunction contributes to cyst development. In epithelial cells, changes in apical fluid flow induce cilia-mediated Ca2+entry via polycystin-2 (PC2), a cation channel. The Oak Ridge Polycystic Kidney ( orpk) mouse contains a mutated Tg737 gene that disrupts expression of polaris, a protein required for ciliogenesis. These studies examine the effect of cilia malformation on Ca2+entry in orpk cilia(−) collecting duct principal cells, and in orpk cells in which wild-type Tg737 was reintroduced, orpk cilia(+). [Ca2+]iwas monitored in confluent cell monolayers using fluorescence microscopy. Intrinsic apical Ca2+entry was measured by Mn2+quenching and Ca2+depletion/readdition under flow conditions below the threshold for stimulation. We found that unstimulated apical Ca2+entry was markedly increased in cilia(−) cells and was sensitive to Gd3+, an inhibitor of PC2. Electrophysiological measurements demonstrate increased abundance of an apical channel, consistent with PC2, in cilia(−) cells. Immunofluorescence studies revealed that PC2, normally expressed on and at the base of cilia in orpk cilia(+) cells, was observed throughout the apical membrane in cilia(−) cells. Furthermore, cilia(−) cells displayed elevated subapical Ca2+levels measured with the near-membrane Ca2+indicator FFP-18. We propose that cilia exert a tonic regulatory influence on apical Ca2+entry, and absence of cilia results in loss of spatial organization of PC2, causing unregulated Ca2+entry and elevations in subapical [Ca2+], a factor which may contribute to cyst formation.
Can a membrane oxygenator be a model for lung NO and CO transfer?
Authors: Borland Colin , Dunningham Helen , Bottrill Fiona , Vuylsteke Alain
Published: January 2006

To model lung nitric oxide (NO) and carbon monoxide (CO) uptake, a membrane oxygenator circuit was primed with horse blood flowing at 2.5 l/min. Its gas channel was ventilated with 5 parts/million NO, 0.02% CO, and 22% O2at 5 l/min. NO diffusing capacity (Dno) and CO diffusing capacity (Dco) were calculated from inlet and outlet gas concentrations and flow rates: Dno = 13.45 ml·min−1·Torr−1(SD 5.84) and Dco = 1.22 ml·min−1·Torr−1(SD 0.3). Dno and Dco increased ( P = 0.002) with blood volume/surface area. 1/Dno ( P < 0.001) and 1/Dco ( P < 0.001) increased with 1/Hb. Dno ( P = 0.01) and Dco ( P = 0.004) fell with increasing gas flow. Dno but not Dco increased with hemolysis ( P = 0.001), indicating Dno dependence on red cell diffusive resistance. The posthemolysis value for membrane diffusing capacity = 41 ml·min−1·Torr−1is the true membrane diffusing capacity of the system. No change in Dno or Dco occurred with changing blood flow rate. 1/Dco increased ( P = 0.009) with increasing Po2. Dno and Dco appear to be diffusion limited, and Dco reaction limited. In this apparatus, the red cell and plasma offer a significant barrier to NO but not CO diffusion. Applying the Roughton-Forster model yields similar specific transfer conductance of blood per milliliter for NO and CO to previous estimates. This approach allows alteration of membrane area/blood volume, blood flow, gas flow, oxygen tension, red cell integrity, and hematocrit (over a larger range than encountered clinically), while keeping other variables constant. Although structurally very different, it offers a functional model of lung NO and CO transfer.
Amplitude cancellation reduces the size of motor unit potentials averaged from the surface EMG
Authors: Keenan Kevin G. , Farina Dario , Merletti Roberto , Enoka Roger M.
Published: January 2006

The purpose of the study was to evaluate the influence of selected physiological parameters on amplitude cancellation in the simulated surface electromyogram (EMG) and the consequences for spike-triggered averages of motor unit potentials derived from the interference and rectified EMG signals. The surface EMG was simulated from prescribed recruitment and rate coding characteristics of a motor unit population. The potentials of the motor units were detected on the skin over a hand muscle with a bipolar electrode configuration. Averages derived from the EMG signal were generated using the discharge times for each of the 24 motor units with lowest recruitment thresholds from a population of 120 across three conditions: 1) excitation level; 2) motor unit conduction velocity; and 3) motor unit synchronization. The area of the surface-detected potential was compared with potentials averaged from the interference, rectified, and no-cancellation EMGs. The no-cancellation EMG comprised motor unit potentials that were rectified before they were summed, thereby preventing cancellation between the opposite phases of the potentials. The percent decrease in area of potentials extracted from the rectified EMG was linearly related to the amount of amplitude cancellation in the interference EMG signal, with the amount of cancellation influenced by variation in excitation level and motor unit conduction velocity. Motor unit synchronization increased potentials derived from both the rectified and interference EMG signals, although cancellation limited the increase in area for both potentials. These findings document the influence of amplitude cancellation on motor unit potentials averaged from the surface EMG and the consequences for using the procedure to characterize motor unit properties.
Three-color cDNA microarrays with prehybridization quality control yield gene expression data comparable to that of commercial platforms
Authors: Hessner Martin J. , Xiang Bixia , Jia Shuang , Geoffrey Rhonda , Holmes Shannon , Meyer Lisa , Muheisen Sanaa , Wang Xujing
Published: January 2006

Despite their lower cost and high content flexibility, a limitation of in-house-prepared arrays has been their susceptibility to quality control (QC) issues and lack of QC standards across laboratories. Therefore, we developed a novel three-color array system that allows prehybridization QC as well as the Matarray software to facilitate acquisition of accurate gene expression data. In this study, we compared performance of our rat cDNA array to the Affymetrix RG-U34A and Agilent G4130A arrays using 2,824 UniGenes represented on all three arrays. Before data filtering, poor interplatform agreement was observed; however, after data filtering, differentially expressed UniGenes exhibited correlation coefficients of 0.91, 0.88, and 0.92 between the Affymetrix vs. Agilent, Affymetrix vs. cDNA, and Agilent vs. cDNA arrays, respectively. The Affymetrix, Agilent, and cDNA arrays agreed well with quantitative RT-PCR conducted on 42 UniGenes, yielding correlation coefficients of 0.90, 0.90, and 0.96, respectively. Each platform underestimated ratios relative to quantitative RT-PCR, possessing respective slopes of 0.86 ( R2 = 0.81), 0.65 ( R2 = 0.81), and 0.70 ( R2 = 0.92). Overall, these data show that the combination of our novel technical and analytic approaches yield an accurate platform for functional genomics that is concordant with commercial discovery arrays in terms of identifying regulated genes and pathways.
Progress in Female Sexual Dysfunction
Authors: Verit Fatma Ferda , Yeni Ercan , Kafali Hasan
Published: January 2006

Introduction: Female sexual dysfunction (FSD) is a significant age-related, progressive and highly prevalent problem that affects a substantial number of women that causes personal distress and has negative effects on quality of life and interpersonal relationships. Definitions: The female sexual response cycle consists of three phases: desire, arousal, and orgasm, and is initiated by non-adrenergic/non-cholinergic, e.g. vasoactive intestinal polypeptide and nitric oxide, neurotransmitters that maintain vascular and non-vascular smooth muscle relaxation resulting in increased pelvic blood flow, vaginal lubrication, and clitoral and labial engorgement. Furthermore, hormonal status may influence female sexual function. For the diagnosis of FSD, a detailed history should be taken initially, followed by a physical examination and laboratory studies. Conclusion: Due to the fact that there has been little research and attention on FSD, our knowledge in this field is quite limited and there is still no approved therapy. Future advances in evaluation and treatment of female sexual problems are forthcoming.
Risk Factors for Benign Prostatic Hyperplasia in South Korean Men
Authors: Hong Juhee , Kwon Sungwon , Yoon Hana , Lee Hunjae , Lee Boeun , Kim Han Hae , Jeong Eun Kyeong , Park Hyesook
Published: January 2006

Objectives: Benign prostatic hyperplasia (BPH) is the most common prostate disease in middle-aged and elderly men, and leads to severe impairment in later life. Despite the significant effect on public health, the causes of BPH have received little attention. Identifying risk factors for BPH is crucial for understanding the etiology and for determining effective interventions or targeting strategies. Methods: This survey was performed in two steps: (1) a pilot study was first conducted prior to the main study in order to estimate baseline characteristics, and (2) the main study investigated the prevalence and risk factors of BPH using clinical diagnostic tests and a questionnaire. A total of 641 males, aged 50–79 years, participated in this community-based cross-sectional study. Results: Age was the only significant demographic risk factor of BPH. The presence of chronic bronchitis and a high prostate-specific antigen (PSA) level increased the risk by three- and twofold, respectively. The risk decreased as drinking frequency increased. Physical activity 3–5 times/week reduced the risk relative to being active less than twice per week; however, engaging in physical activity nearly everyday increased the risk 1.7-fold relative to being active up to twice per week. Conclusions: Although BPH has been considered a disease that is unavoidable with advancing age, the clear identification and control of the underlying risk factors might allow effective prevention by placing a special emphasis on those at risk.
Can the Effect of Antibiotherapy and Anti-Inflammatory Therapy on Serum PSA Levels Discriminate between Benign and Malign Prostatic Pathologies?
Authors: Erol Haluk , Beder Nahit , Çalişkan Tamer , Dündar Mehmet , İnsal Alparslan , Çulhaci Nil
Published: January 2006

Objective: The primary aim was to evaluate the change in the total and free PSA levels after antibiotic and non-steroid anti-inflammatory treatment. The secondary aim was to compare this change among the histological subgroups to assess whether it was discriminating. Methods: 97 consecutive patients with PSA >4 ng/dl and scheduled for prostate biopsy were included in this prospective study. 65 patients (group 1) were then put on medical treatment of ciprofloxacin 500 mg bid and diclofenac sodium 75 mg during the routine waiting period before the 2- to 3-week procedure. Randomly selected (every third case) 32 patients (group 2) did not receive this treatment. Free and total PSA tests were repeated before the procedure. The change in the PSA values was compared between the groups and among the histological subgroups in group 1. Results: While in group 1 the decrease in PSA was significant (p = 0.000), this was not the case in group 2. The difference in free PSA values was unremarkable for both groups. In histologically determined cancer cases of group 1, the difference between pre- and post-procedure PSA level was not of note, while in BPH and prostatitis cases it was significant. Conclusion: In cases with increased PSA, medical treatment for a likely subclinical prostatitis resulted in a decrease of PSA, which was significant only in benign conditions.
Comparison of the Clinical Value of Complexed PSA and Total PSA in the Discrimination between Benign Prostatic Hyperplasia and Prostate Cancer
Authors: Froehner Michael , Hakenberg Oliver W. , Koch Rainer , Schmidt Uta , Meye Axel , Wirth Manfred P.
Published: January 2006

Background: To compare the clinical value of the measurement of complex and total PSA in the discrimination between benign prostatic hyperplasia (BPH) and prostate cancer. Methods: In serum samples collected from 166 men with histopathologically proven clinically localized prostate cancer and of 97 men with BPH, total prostate-specific antigen (PSA), complexed PSA and the free to total PSA ratio were determined. The statistical analysis was done by the comparison of the receiver operator characteristic (ROC) curves. Results: The areas under the ROC curves were 0.776 for total PSA, 0.799 for complexed PSA (total PSA vs. cPSA: p < 0.0001) and 0.812 for the free to total PSA ratio. With a cut-off of 3.0 ng/ml for complexed PSA, the sensitivity was 90%, the specificity 58%, the positive and the negative predictive values 79 and 78%, respectively. With a cut-off of 4.0 ng/ml for total PSA, the sensitivity was 87%, the specificity 59%, the positive and the negative predictive values were 78 and 72%, respectively. Conclusions: There was a statistically significant advantage for complexed PSA compared to total PSA in the discrimination between BPH and prostate cancer. The difference was, however, small and its clinical relevance is questionable.