bluuebunny/crossref_metadata_2025 huggingface dataset:
Vardenafil Improves Erectile Function in Men with Erectile Dysfunction Irrespective of Disease Severity and Disease Classification
Authors: Donatucci Craig , Eardley Ian , Buvat Jacques , Gittelman Marc , Kell Phillip , Segerson Thom , Homering Martin , Montorsi Francesco
Published: October 2004

Background

Vardenafil (Levitra®) is a potent and selective phosphodiesterase 5 (PDE5) inhibitor used in the management of erectile dysfunction (ED). This retrospective subgroup analysis assessed the effectiveness of vardenafil treatment in men with ED of different baseline severity and disease classification.

Methods

Data from two pivotal, randomized, double-blind, placebo-controlled clinical trials enrolling men from the general ED population who received placebo or vardenafil 5 mg, 10 mg, or 20 mg during a 12-week treatment period were retrospectively analysed, stratifying by psychogenic, organic, and mixed ED disease classification as determined by the investigator. Efficacy endpoints included the International Index of Erectile Function (IIEF)-Erectile Function (EF) domain score, per-patient diary response rates to questions on penile insertion [Sexual Encounter Profile (SEP-2)] and maintenance of erection (SEP-3) and rates of positive response to the Global Assessment Question (GAQ).

Results

Data from 1,385 men who received at least one dose of study medication and had pre- and post-baseline measures of efficacy available (intent-to-treat population) are presented. At baseline 37–41% of patients had severe ED, 30–34% moderate, 22% mild-to-moderate and 6–8% mild ED. At baseline, 46–51% of patients were considered to have an organic cause for ED, 13–16% psychogenic ED, and 36–38% mixed classification of ED. For all classifications and for mild-to-moderate to severe ED, men treated with 10 or 20 mg of vardenafil showed statistically and clinically  significant  improvements  (P < 0.001)  in  IIEF-EF  scores,  diary  response  rates  to  the SEP-2 and SEP-3 questions, and GAQ as compared with those given placebo. The greatest improvements relative to placebo were noted in patients with more severe ED. The most common treatment-emergent adverse events were headache, flushing, rhinitis, dyspepsia, and were dose-related, mostly mild to moderate in intensity and consistent with the class.

Conclusion

Vardenafil improves EF in men with ED irrespective of investigator-determined classification and baseline ED severity.
Penile Prosthetic Surgery for Peyronie's Disease: Defining the Need for Intraoperative Adjuvant Maneuvers
Authors: Mulhall John , Ahmed Absaar , Anderson Mathew
Published: October 2004

Introduction

There are a number of accepted approaches to the patient with Peyronie's disease and erectile dysfunction (ED), including penile prosthesis surgery. During prosthesis surgery for Peyronie's disease some men are left with residual curvature upon maximum device inflation. This analysis was undertaken to define how often and in which patients, intra-operative adjuvant maneuvers are required.

Methods

Men undergoing penile prosthesis surgery for combined Peyronie's disease/ED constituted the study population. Residual curvature >10° was deemed to warrant the use of a secondary maneuver to correct curvature. In this analysis, plaque release incisions were utilized and grafting was performed only if there was overt exposure of the prosthesis.

Results

36 men were included in the analysis. All patients with preoperative curvatures ≤30° had complete resolution of the penile curvature with full inflation of the prosthesis alone. Of patients who had >45° curvature preoperatively, 86% needed plaque incision to achieve adequate penile straightening. Grafting was required in only 5.5% patients and both of these patients had preoperative curvature >60°.

Conclusion

In 61% of patients with combined Peyronie's disease/ED in this study, the placement of a three-piece inflatable penile prosthesis alone corrected the penile curvature. 86% of patients requiring plaque incision had preoperative curvatures >45°. This information should enable surgeons to plan such operations more effectively and to counsel patients more comprehensively prior to operative intervention.
Flagellin fromListeria monocytogenesIs Glycosylated with β-O-LinkedN-Acetylglucosamine
Authors: Schirm M. , Kalmokoff M. , Aubry A. , Thibault P. , Sandoz M. , Logan S. M.
Published: October 2004

Glycan staining of purified flagellin fromListeria monocytogenesserotypes 1/2a, 1/2b, 1/2c, and 4b suggested that the flagellin protein from this organism is glycosylated. Mass spectrometry analysis demonstrated that the flagellin protein ofL. monocytogenesis posttranslationally modified with O-linkedN-acetylglucosamine (GlcNAc) at up to six sites/monomer. The sites of glycosylation are all located in the central, surface-exposed region of the protein monomer. Immunoblotting with a monoclonal antibody specific for β-O-linked GlcNAc confirmed that the linkage was in the β configuration, this residue being a posttranslational modification commonly observed in eukaryote nuclear and cytoplasmic proteins.
Murein (Peptidoglycan) Binding Property of the Essential Cell Division Protein FtsN from
Escherichia coli
Authors: Ursinus Astrid , van den Ent Fusinita , Brechtel Sonja , de Pedro Miguel , Höltje Joachim-Volker , Löwe Jan , Vollmer Waldemar
Published: October 2004

The binding of the essential cell division protein FtsN of
Escherichia coli
to the murein (peptidoglycan) sacculus was studied. Soluble truncated variants of FtsN, including the complete periplasmic part of the protein as well as a variant containing only the C-terminal 77 amino acids, did bind to purified murein sacculi isolated from wild-type cells. FtsN variants lacking this C-terminal region showed reduced or no binding to murein. Binding of FtsN was severely reduced when tested against sacculi isolated either from filamentous cells with blocked cell division or from chain-forming cells of a triple amidase mutant. Binding experiments with radioactively labeled murein digestion products revealed that the longer murein glycan strands (>25 disaccharide units) showed a specific affinity to FtsN, but neither muropeptides, peptides, nor short glycan fragments bound to FtsN. In vivo FtsN could be cross-linked to murein with the soluble disulfide bridge containing cross-linker DTSSP. Less FtsN, but similar amounts of OmpA, was cross-linked to murein of filamentous or of chain-forming cells compared to levels in wild-type cells. Expression of truncated FtsN variants in cells depleted in full-length FtsN revealed that the presence of the C-terminal murein-binding domain was not required for cell division under laboratory conditions. FtsN was present in 3,000 to 6,000 copies per cell in exponentially growing wild-type
E. coli
MC1061. We discuss the possibilities that the binding of FtsN to murein during cell division might either stabilize the septal region or might have a function unrelated to cell division.
Concerted Effects of Amino Acid Substitutions in Conserved Charged Residues and Other Residues in the Cytoplasmic Domain of PomA, a Stator Component of Na
+
-Driven Flagella
Authors: Fukuoka Hajime , Yakushi Toshiharu , Homma Michio
Published: October 2004

PomA is a membrane protein that is one of the essential components of the sodium-driven flagellar motor in
Vibrio
species. The cytoplasmic charged residues of
Escherichia coli
MotA, which is a PomA homolog, are believed to be required for the interaction of MotA with the C-terminal region of FliG. It was previously shown that a PomA variant with neutral substitutions in the conserved charged residues (R88A, K89A, E96Q, E97Q, and E99Q; AAQQQ) was functional. In the present study, five other conserved charged residues were replaced with neutral amino acids in the AAQQQ PomA protein. These additional substitutions did not affect the function of PomA. However, strains expressing the AAQQQ PomA variant with either an L131F or a T132M substitution, neither of which affected motor function alone, exhibited a temperature-sensitive (TS) motility phenotype. The double substitutions R88A or E96Q together with L131F were sufficient for the TS phenotype. The motility of the PomA TS mutants immediately ceased upon a temperature shift from 20 to 42°C and was restored to the original level approximately 10 min after the temperature was returned to 20°C. It is believed that PomA forms a channel complex with PomB. The complex formation of TS PomA and PomB did not seem to be affected by temperature. Suppressor mutations of the TS phenotype were mapped in the cytoplasmic boundaries of the transmembrane segments of PomA. We suggest that the cytoplasmic surface of PomA is changed by the amino acid substitutions and that the interaction of this surface with the FliG C-terminal region is temperature sensitive.
FtsZ Collaborates with Penicillin Binding Proteins To Generate Bacterial Cell Shape inEscherichia coli
Authors: Varma Archana , Young Kevin D.
Published: October 2004

The mechanisms by which bacteria adopt and maintain individual shapes remain enigmatic. Outstanding questions include why cells are a certain size, length, and width; why they are uniform or irregular; and why some branch while others do not. Previously, we showed thatEscherichia colimutants lacking multiple penicillin binding proteins (PBPs) display extensive morphological diversity. Because defective sites in these cells exhibit the structural and functional characteristics of improperly localized poles, we investigated the connection between cell division and shape. Here we show that under semipermissive conditions the temperature-sensitive FtsZ84 protein produces branched and aberrant cells at a high frequency in mutants lacking PBP 5, and this phenotype is exacerbated by the loss of additional peptidoglycan endopeptidases. Surprisingly, certainftsZ84strains lyse at the nonpermissive temperature instead of filamenting, and inhibition of wild-type FtsZ forces some mutants into tightly wound spirillum-like morphologies. The results demonstrate that significant aspects of bacterial shape are dictated by a previously unrecognized relationship between the septation machinery and ostensibly minor peptidoglycan-modifying enzymes and that under certain circumstances improper FtsZ function can destroy the structural integrity of the cell.
PAS Domain of the Aer Redox Sensor Requires C-Terminal Residues for Native-Fold Formation and Flavin Adenine Dinucleotide Binding
Authors: Herrmann Sarah , Ma Qinhong , Johnson Mark S. , Repik Alexandre V. , Taylor Barry L.
Published: October 2004

The Aer protein inEscherichia coliis a membrane-bound, FAD-containing aerotaxis and energy sensor that putatively monitors the redox state of the electron transport system. Binding of FAD to Aer requires the N-terminal PAS domain and residues in the F1 region and C-terminal HAMP domain. The PAS domains of other PAS proteins are soluble in water. To investigate properties of the PAS domain, we subcloned segments of theaergene fromE. colithat encode the PAS domain with and without His6tags and expressed the PAS peptides inE. coli. The 20-kDa His6-Aer2-166PAS-F1 fragment was purified as an 800-kDa complex by gel filtration chromatography, and the associating protein was identified by N-terminal sequencing as the chaperone protein GroEL. None of the N-terminal fragments of Aer found in the soluble fraction was released from GroEL, suggesting that these peptides do not fold correctly in an aqueous environment and require a motif external to the PAS domain for proper folding. Consistent with this model, peptide fragments that included the membrane binding region and part (Aer2-231) or all (Aer2-285) of the HAMP domain inserted into the membrane, indicating that they were released by GroEL. Aer2-285, but not Aer2-231, bound FAD, confirming the requirement for the HAMP domain in stabilizing FAD binding. The results raise an interesting possibility that residues outside the PAS domain that are required for FAD binding are essential for formation of the PAS native fold.
Methylation of GPLs inMycobacterium smegmatisandMycobacterium avium
Authors: Jeevarajah Dharshini , Patterson John H. , Taig Ellen , Sargeant Tobias , McConville Malcolm J. , Billman-Jacobe Helen
Published: October 2004

Several species of mycobacteria express abundant glycopeptidolipids (GPLs) on the surfaces of their cells. The GPLs are glycolipids that contain modified sugars including acetylated 6-deoxy-talose and methylated rhamnose. Four methyltransferases have been implicated in the synthesis of the GPLs ofMycobacterium smegmatisandMycobacterium avium.A rhamnosyl 3-O-methytransferase and a fatty acid methyltransferase ofM. smegmatishave been previously characterized. In this paper, we characterize the methyltransferases that are responsible for modifying the hydroxyl groups at positions 2 and 4 of rhamnose and propose the biosynthetic sequence of GPL trimethylrhamnose formation. The analysis ofM. aviumgenes through the creation of specific mutants is technically difficult; therefore, an alternative approach to determine the function of putative methyltransferases ofM. aviumwas undertaken. Complementation ofM. smegmatismethyltransferase mutants withM. aviumgenes revealed that MtfC and MtfB of the latter species have 4-O-methyltransferase activity and that MtfD is a 3-O-methyltransferase which can modify rhamnose of GPLs inM. smegmatis.
The Transcriptional Regulator AlgR Controls Cyanide Production in
Pseudomonas aeruginosa
Authors: Carterson Alexander J. , Morici Lisa A. , Jackson Debra W. , Frisk Anders , Lizewski Stephen E. , Jupiter Ryan , Simpson Kendra , Kunz Daniel A. , Davis Scott H. , Schurr Jill R. , Hassett Daniel J. , Schurr Michael J.
Published: October 2004

Pseudomonas aeruginosa
is an opportunistic pathogen that causes chronic lung infections in cystic fibrosis (CF) patients. One characteristic of
P. aeruginosa
CF isolates is the overproduction of the exopolysaccharide alginate, controlled by AlgR. Transcriptional profiling analyses comparing mucoid
P. aeruginosa
strains to their isogenic
algR
deletion strains showed that the transcription of cyanide-synthesizing genes (
hcnAB
) was ∼3-fold lower in the
algR
mutants. S1 nuclease protection assays corroborated these findings, indicating that AlgR activates
hcnA
transcription in mucoid
P. aeruginosa
. Quantification of hydrogen cyanide (HCN) production from laboratory isolates revealed that mucoid laboratory strains made sevenfold more HCN than their nonmucoid parental strains. In addition, comparison of laboratory and clinically derived nonmucoid strains revealed that HCN was fivefold higher in the nonmucoid CF isolates. Moreover, the average amount of cyanide produced by mucoid clinical isolates was 4.7 ± 0.85 μmol of HCN/mg of protein versus 2.4 ± 0.40 μmol of HCN/mg of protein for nonmucoid strains from a survey conducted with 41
P. aeruginosa
CF isolates from 24 patients. Our data indicate that (i) mucoid
P. aeruginosa
regardless of their origin (laboratory or clinically derived) produce more cyanide than their nonmucoid counterparts, (ii) AlgR regulates HCN production in
P. aeruginosa
, and (iii)
P. aeruginosa
CF isolates are more hypercyanogenic than nonmucoid laboratory strains. Taken together, cyanide production may be a relevant virulence factor in CF lung disease, the production of which is regulated, in part, by AlgR.
Identification of a Reactivating Factor for Adenosylcobalamin-Dependent Ethanolamine Ammonia Lyase
Authors: Mori Koichi , Bando Reiko , Hieda Naoki , Toraya Tetsuo
Published: October 2004

The holoenzyme of adenosylcobalamin-dependent ethanolamine ammonia lyase undergoes suicidal inactivation during catalysis as well as inactivation in the absence of substrate. The inactivation involves the irreversible cleavage of the Co-C bond of the coenzyme. We found that the inactivated holoenzyme undergoes rapid and continuous reactivation in the presence of ATP, Mg
2+
, and free adenosylcobalamin in permeabilized cells (in situ), homogenate, and cell extracts of
Escherichia coli
. The reactivation was observed in the permeabilized
E. coli
cells carrying a plasmid containing the
E. coli eut
operon as well. From coexpression experiments, it was demonstrated that the
eutA
gene, adjacent to the 5′ end of ethanolamine ammonia lyase genes (
eutBC
), is essential for reactivation. It encodes a polypeptide consisting of 467 amino acid residues with predicted molecular weight of 49,599. No evidence was obtained that shows the presence of the auxiliary protein(s) potentiating the reactivation or associating with EutA. It was demonstrated with purified recombinant EutA that both the suicidally inactivated and O
2
-inactivated holoethanolamine ammonia lyase underwent rapid reactivation in vitro by EutA in the presence of adenosylcobalamin, ATP, and Mg
2+
. The inactive enzyme-cyanocobalamin complex was also activated in situ and in vitro by EutA under the same conditions. Thus, it was concluded that EutA is the only component of the reactivating factor for ethanolamine ammonia lyase and that reactivation and activation occur through the exchange of modified coenzyme for free intact adenosylcobalamin.
Isolation and Characterization of Ribosomes and Translation Initiation Factors from the Gram-Positive Soil Bacterium
Streptomyces lividans
Authors: Day J. Michael , Janssen Gary R.
Published: October 2004

A primer extension inhibition (toeprint) assay was developed using ribosomes and ribosomal subunits from
Streptomyces lividans
. This assay allowed the study of ribosome binding to streptomycete leaderless and leadered mRNA. Purified 30S subunits were unable to form a ternary complex on
aph
leaderless mRNA, whereas 70S ribosomes could form ternary complexes on this mRNA. 30S subunits formed ternary complexes on leadered
aph
and
malE
mRNA. The translation initiation factors (IF1, IF2, and IF3) from
S. lividans
were isolated and included in toeprint and filter binding assays with leadered and leaderless mRNA. Generally, the IFs reduced the toeprint signal on leadered mRNA; however, incubation of IF1 and IF2 with 30S subunits that had been washed under high-salt conditions promoted the formation of a ternary complex on
aph
leaderless mRNA. Our data suggest that, as reported for
Escherichia coli
, initiation complexes with leaderless mRNAs might use a novel pathway involving 70S ribosomes or 30S subunits bound by IF1 and IF2 but not IF3. Some mRNA-ribosome-initiator tRNA reactions that yielded weak or no toeprint signals still formed complexes in filter binding assays, suggesting the occurrence of interactions that are not stable in the toeprint assay.
Isolation, Free-Living Capacities, and Genome Structure of “
Candidatus
Glomeribacter gigasporarum,” the Endocellular Bacterium of the Mycorrhizal Fungus
Gigaspora margarita
Authors: Jargeat P. , Cosseau C. , Ola'h B. , Jauneau A. , Bonfante P. , Batut J. , Bécard G.
Published: October 2004

“
Candidatus
Glomeribacter gigasporarum” is an endocellular β-proteobacterium present in the arbuscular mycorrhizal (AM) fungus
Gigaspora margarita
. We established a protocol to isolate “
Ca
. Glomeribacter gigasporarum” from its host which allowed us to carry out morphological, physiological, and genomic investigations on purified bacteria. They are rod shaped, with a cell wall typical of gram-negative bacteria and a cytoplasm rich in ribosomes, and they present no flagella or pili. Isolated bacteria could not be grown in any of the 19 culture media tested, but they could be kept alive for up to 4 weeks. PCR-based investigations of purified DNA from isolated bacteria did not confirm the presence of all genes previously assigned to “
Ca
. Glomeribacter gigasporarum.” In particular, the presence of
nif
genes could not be detected. Pulsed-field gel electrophoresis analyses allowed us to estimate the genome size of “
Ca
. Glomeribacter gigasporarum” to approximately 1.4 Mb with a ca. 750-kb chromosome and a 600- to 650-kb plasmid. This is the smallest genome known for a β-proteobacterium. Such small genome sizes are typically found in endocellular bacteria living permanently in their host. Altogether, our data suggest that “
Ca
. Glomeribacter gigasporarum” is an ancient obligate endocellular bacterium of the AM fungus
G. margarita
.
Errata: "Autonomous Learning Based on Cost Assumptions: Theoretical Studies and Experiments in Robot Control"
Authors: RIBEIRO CARLOS H. C. , HEMERLY ELDER M.
Published: October 2004

Autonomous learning techniques are based on experience acquisition. In most realistic applications, experience is time-consuming: it implies sensor reading, actuator control and algorithmic update, constrained by the learning system dynamics. The information crudeness upon which classical learning algorithms operate make such problems too difficult and unrealistic. Nonetheless, additional information for facilitating the learning process ideally should be embedded in such a way that the structural, well-studied characteristics of these fundamental algorithms are maintained. We investigate in this article a more general formulation of the Q-learning method that allows for a spreading of information derived from single updates towards a neighbourhood of the instantly visited state and converges to optimality. We show how this new formulation can be used as a mechanism to safely embed prior knowledge about the structure of the state space, and demonstrate it in a modified implementation of a reinforcement learning algorithm in a real robot navigation task.
OPINION EVOLUTION MODEL WITH THE STATE OF NEUTRALITY
Authors: HE MINGFENG , SUN QI , WANG HAISHAN
Published: October 2004

We propose a mechanism of opinion evolution in a closed system. The opinion evolution process can be described as the disposal of multi-information inputs with one opinion accepted as the output. We introduce the opinion neutrality in the system, observing the characteristics of the opinion evolution process; and find that the initial opinion distribution fractions play an important role in the final results. When the two opposite opinions' fraction are equal, the neutrality fraction will affect the final opinion distribution dramatically.
FAULT-TOLERANT NANOCOMPUTERS BASED ON ASYNCHRONOUS CELLULAR AUTOMATA
Authors: ISOKAWA TEIJIRO , ABO FUKUTARO , PEPER FERDINAND , ADACHI SUSUMU , LEE JIA , MATSUI NOBUYUKI , MASHIKO SHINRO
Published: October 2004

Cellular Automata (CA) are a promising architecture for computers with nanometer-scale sized components, because their regular structure potentially allows chemical manufacturing techniques based on self-organization. With the increase in integration density, however, comes a decrease in the reliability of the components from which such computers will be built. This paper employs BCH error-correcting codes to construct CA with improved reliability. We construct an asynchronous CA of which a quarter of the (ternary) bits storing a cell's state information may be corrupted without affecting the CA's operations, provided errors are evenly distributed over a cell's bits (no burst errors allowed). Under the same condition, the corruption of half of a cell's bits can be detected.
ANALYTICAL AND NUMERICAL SOLUTIONS OF THE SHALLOW WATER EQUATIONS FOR 2D ROTATIONAL FLOWS
Authors: TESHUKOV VLADIMIR , RUSSO GIOVANNI , CHESNOKOV ALEXANDER
Published: October 2004

In this paper we consider a system of integrodifferential equations describing, in a long wave approximation, plane-parallel rotational motions of an ideal incompressible liquid with a free surface. Using special identities, we calculate integral Riemann invariants which are conserved along the trajectories and characteristics. A new class of solutions for this system is found. The description of these special solutions simplifies essentially since in this case the integrodifferential system reduces to a hyperbolic system of two differential equations admitting formulation in the Riemann invariants. The solutions describing propagation of simple waves are obtained in an analytical form. Numerical simulations of rotational flows are performed using both the system describing the special class of the solutions and shallow water equations for rotational flows. In order to describe discontinuous rotational flows, the equations of motion are written in a special conservation form and jump conditions are derived. A non-oscillatory, second-order central scheme is used in the calculations. Some illustrative solutions are presented for smooth and discontinuous rotational flows.
MODIFIED SCATTERING FOR BIPOLAR NONLINEAR SCHRÖDINGER–POISSON EQUATIONS
Authors: HAO CHENGCHUN , HSIAO LING , LI HAILIANG
Published: October 2004

In this paper, we study the asymptotic behavior in time and the existence of the modified scattering operator of the globally defined smooth solutions to the Cauchy problem for the bipolar nonlinear Schrödinger–Poisson equations with small data in the space ℝ3.
MODELLING LIVING FLUIDS WITH THE SUBDIVISION INTO THE COMPONENTS IN TERMS OF PROBABILITY DISTRIBUTIONS
Authors: WILLANDER M. , MAMONTOV E. , CHIRAGWANDI Z.
Published: October 2004

As it follows from the results of C. H. Waddigton, F. E. Yates, A. S. Iberall, and other well-known bio-physicists, living fluids cannot be modelled within the frames of the fundamental assumptions of the statistical-mechanics formalism. One has to go beyond them. The present work does it by means of the generalized kinetics (GK), the theory enabling one to allow for the complex stochasticity of internal properties and parameters of the fluid particles. This is one of the key features which distinguish living fluids from the nonliving ones. It creates the disparity of the particles and hence breaks the each-fluid-component-uniformity requirement underlying statistical mechanics.

The work deals with the corresponding modification of common kinetic equations which is in line with the GK theory and is the complement to the latter. This complement allows a subdivision of a fluid into the fluid components in terms of nondiscrete probability distributions. The treatment leads to one more equation that describes the above internal parameters. The resulting model is the system of these two equations. It appears to be always nonlinear in case of living fluids. In case of nonliving fluids, the model can be linear. Moreover, the living-fluid model, as a whole, cannot have the thermodynamic equilibrium, only partial equilibriums (such as the motional one) are possible. In contrast to this, in case of nonliving fluids, the thermodynamic equilibrium is, of course, possible. The number of the fluid components is treated as the number of the modes of the particle-characteristic probability density. In so doing, a fairly general extension of the notion of the mode from the one-dimensional case to the multidimensional case is proposed. The work also discusses the variety of the time-scales in a living fluid, the simplest quantum-mechanical equation relevant to living fluids, and the non-equilibrium nonlinear stochastic hydrodynamics option. The latter is simpler than, but conceptually comparable to, stochastic kinetic equations. A few directions for future research are suggested. The work notes a cohesion of mathematical physics and fluid mechanics with the living-fluid-related fields as a complex interdisciplinary problem.
FULLY DISCRETE ADAPTIVE METHODS FOR A BLOW-UP PROBLEM
Authors: BRÄNDLE CRISTINA , GROISMAN PABLO , ROSSI JULIO D.
Published: October 2004

We present adaptive procedures in space and time for the numerical study of positive solutions to the following problem: [Formula: see text] with p,m>0. We describe how to perform adaptive methods in order to reproduce the exact asymptotic behavior (the blow-up rate and the blow-up set) of the continuous problem.
ON A NONLINEAR MAXWELL'S SYSTEM IN QUASI-STATIONARY ELECTROMAGNETIC FIELDS
Authors: YIN HONG-MING
Published: October 2004

In this paper we study the motion of a magnetic field H in a conductive medium Ω⊂R3 under the influence of a system generator. By neglecting displacement currents, the magnetic field satisfies a nonlinear Maxwell's system: Ht+∇×[ρ(x,t)∇×H]=f(|H|)H, where f(|H|)H represents the magnetic currents depending upon the strength of H. We prove that under appropriate initial and boundary conditions, the system has a global solution and the solution is also unique. Moreover, we show that the solution H will blow up in finite time if f(s) satisfies certain growth conditions. Finally, we generalize the results to the problem associated with a nonlinear boundary condition.
Opposite effect of cAMP signaling in endothelial barriers of different origin
Authors: Bindewald K. , Gündüz D. , Härtel F. , Peters S. C. , Rodewald C. , Nau S. , Schäfer M. , Neumann J. , Piper H. M. , Noll T.
Published: October 2004

cAMP-mediated signaling mechanisms may destabilize or stabilize the endothelial barrier, depending on the origin of endothelial cells. Here, microvascular coronary [coronary endothelial cells (CEC)] and macrovascular aortic endothelial cell (AEC) monolayers with opposite responses to cAMP were analyzed. Macromolecule permeability, isometric force, activation state of contractile machinery [indicated by phosphorylation of regulatory myosin light chains (MLC), activity of MLC kinase, and MLC phosphatase], and dynamic changes of adhesion complex proteins (translocation of VE-cadherin and paxillin) were determined. cAMP signaling was stimulated by the adenosine receptor agonist 5′- N-(ethylcarboxamido)-adenosine (NECA), the β-adrenoceptor agonist isoproterenol (Iso), or by the adenylyl cyclase activator forskolin (FSK). Permeability was increased in CEC and decreased in AEC on stimulation with NECA, Iso, or FSK. The effects could be inhibited by the PKA inhibitor Rp-8-CPT-cAMPS and imitated by the PKA activator Sp-cAMPS. Under cAMP/PKA-dependent stimulation, isometric force and MLC phosphorylation were reduced in monolayers of either cell type, due to an activation of MLC phosphatase. In CEC but not in AEC, FSK induced delocalization of VE-cadherin and paxillin from cellular adhesion complexes as indicated by cell fractionation and immunofluorescence microscopy. In conclusion, decline in contractile activation and isometric force contribute to cAMP/PKA-mediated stabilization of barrier function in AEC. In CEC, this stabilizing effect is overruled by cAMP-induced disintegration of cell adhesion structures.
Is aldosterone synthesized within the rat brain?
Authors: Gomez-Sanchez Elise P. , Ahmad Naveed , Romero Damian G. , Gomez-Sanchez Celso E.
Published: October 2004

Very small amounts of adrenocorticosteroids are synthesized by brain tissue in vitro. While there is evidence suggesting that the synthesis of aldosterone in the brain may have a role in the hypertension of the Dahl salt-sensitive rat, the de novo synthesis of aldosterone or corticosterone within the brain of a living animal has not been demonstrated. We have used sensitive ELISAs to measure aldosterone and corticosterone in the plasma and whole brains of intact rats receiving a normal-, low-, or high-salt diet to alter adrenal aldosterone production and of adrenalectomized rats provided sodium replacement, some of which received aldosterone, corticosterone, or DOC replacement. The results of several experiments were consistent. In intact rats, the brain concentration of aldosterone and corticosterone reflected that in the plasma. However, whereas aldosterone and corticosterone were undetectable or barely undetectable in the plasma of adrenalectomized animals, as was the corticosterone in their brains, aldosterone was consistently found in the brains of adrenalectomized rats, ranging from a mean of 6.6–41 pg/g, depending on the experiment. Provision of DOC as substrate for the endogenous aldosterone synthase and 11β-hydroxylase did not significantly increase brain aldosterone or corticosterone content. It is postulated that the small amounts of aldosterone synthesized in the brain could provide a local ligand for autocrine or paracrine activation of the mineralocorticoid receptor.
Anaplerotic input is sufficient to induce time-dependent potentiation of insulin release in rat pancreatic islets
Authors: Gunawardana Subhadra C. , Liu Yi-Jia , MacDonald Michael J. , Straub Susanne G. , Sharp Geoffrey W. G.
Published: October 2004

Nutrients that induce biphasic insulin release, such as glucose and leucine, provide acetyl-CoA and anaplerotic input in the β-cell. The first phase of release requires increased ATP production leading to increased intracellular Ca2+concentration ([Ca2+]i). The second phase requires increased [Ca2+]iand anaplerosis. There is strong evidence to indicate that the second phase is due to augmentation of Ca2+-stimulated release via the KATPchannel-independent pathway. To test whether the phenomenon of time-dependent potentiation (TDP) has similar properties to the ATP-sensitive K+channel-independent pathway, we monitored the ability of different agents that provide acetyl-CoA and anaplerotic input or both of these inputs to induce TDP. The results show that anaplerotic input is sufficient to induce TDP. Interestingly, among the agents tested, the nonsecretagogue glutamine, the nonhydrolyzable analog of leucine aminobicyclo[2.2.1]heptane-2-carboxylic acid, and succinic acid methyl ester all induced TDP, and all significantly increased α-ketoglutarate levels in the islets. In conclusion, anaplerosis that enhances the supply and utilization of α-ketoglutarate in the tricarboxylic acid cycle appears to play an essential role in the generation of TDP.
β2-Agonist administration increases sarcoplasmic reticulum Ca2+-ATPase activity in aged rat skeletal muscle
Authors: Schertzer Jonathan D. , Plant David R. , Ryall James G. , Beitzel Felice , Stupka Nicole , Lynch Gordon S.
Published: October 2004

Aging is associated with a slowing of skeletal muscle contractile properties, including a decreased rate of relaxation. In rats, the age-related decrease in the maximal rate of relaxation is reversed after 4-wk administration with the β2-adrenoceptor agonist (β2-agonist) fenoterol. Given the critical role of the sarcoplasmic reticulum (SR) in regulating intracellular Ca2+transients and ultimately the time course of muscle contraction and relaxation, we tested the hypothesis that the mechanisms of action of fenoterol are mediated by alterations in SR proteins. Sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) kinetic properties were assessed in muscle homogenates and enriched SR membranes isolated from the red (RG) and white (WG) portions of the gastrocnemius muscle in adult (16 mo) and aged (28 mo) F344 rats that had been administered fenoterol for 4 wk (1.4 mg/kg/day ip, in saline) or vehicle only. Aging was associated with a 29% decrease in the maximal activity ( Vmax) of SERCA in the RG but not in the WG muscles. Fenoterol treatment increased the Vmaxof SERCA and SERCA1 protein levels in RG and WG. In the RG, fenoterol administration reversed an age-related selective nitration of the SERCA2a isoform. Our findings demonstrate that the mechanisms underlying age-related changes in contractile properties are fiber type dependent, whereas the effects of fenoterol administration are independent of age and fiber type.
Cell-to-cell contact influences proliferative marker expression and apoptosis in MIN6 cells grown in islet-like structures
Authors: Luther Melanie J. , Davies Emma , Muller Dany , Harrison Moira , Bone Adrian J. , Persaud Shanta J. , Jones Peter M.
Published: October 2004

Cell-to-cell interactions play an important role in the development and maintenance of the β-cell phenotype. Here, we have investigated whether E-cadherin plays a role in regulating the growth of insulin-secreting MIN6 cells configured as three-dimensional islet-like clusters (pseudoislets). Pseudoislets form by cell aggregation rather than by proliferation from individual cells and attain the size of primary mouse islets after ∼7 days of maintenance in culture. E-cadherin is known to mediate homotypic cell adhesion between β-cells and has also been implicated in a number of cellular processes, including proliferation, apoptosis, and differentiation. E-cadherin and its associated intracellular elements, α- and β-catenin, were upregulated in MIN6 pseudoislets. Pseudoislet formation was associated with an increased expression of cyclin-dependent kinase inhibitors and a concomitant downregulation of Ki67, suggesting an overall reduction in cellular proliferation. However, measurements of 5-bromo-2′-deoxyuridine incorporation revealed that there were no differences in the rate of MIN6 cell proliferation whether they were configured as monolayers or as pseudoislets, which is likely to be a result of their being a transformed cell line. Cells within pseudoislets were not necrotic, but apoptosis appeared to be upregulated in the islet-like structures. However, no differential expression of Fas and FasL was detected in monolayers and pseudoislets. These results suggest that cell-to-cell interactions within islet-like structures may initiate antiproliferative and proapoptotic signals.
Leptin deficiency enhances sensitivity of rats to alcoholic steatohepatitis through suppression of metallothionein
Authors: Tomita Kengo , Azuma Toshifumi , Kitamura Naoto , Tamiya Gen , Ando Satoshi , Nagata Hiroshi , Kato Shinzo , Inokuchi Sayaka , Nishimura Takeshi , Ishii Hiromasa , Hibi Toshifumi
Published: October 2004

Oxidative stress is stated to be a central mechanism of hepatocellular injury in alcohol-induced liver injury. Recent reports have shown that Kupffer cell dysfunction in the leptin-deficient state contributes partly to the increased sensitivity to endotoxin liver injury. Here we report that leptin also plays a key role in the development of alcoholic liver injury and that leptin signaling in hepatocytes is involved in cellular mechanisms that mediate ethanol-induced oxidative stress. We found that chronic ethanol feeding in leptin receptor-deficient Zucker (fa/fa) rats for 6 wk resulted in a much more severe liver injury and augmented accumulation of hepatic lipid peroxidation compared with control littermates. The hepatic induction of stress-response and antioxidant proteins, such as metallothionein (MT)-1 and -2, was significantly suppressed in fa/fa rats after chronic ethanol feeding. Zinc concentration in liver was also decreased in fa/fa rats, compared with control littermates. In primary cultured hepatocytes from fa/fa rats, incubation with ethanol significantly suppressed MT-1 and -2 expressions. Addition of leptin to leptin-deficient ob/ob mouse primary hepatocytes led to an increase in MT-1 and -2 mRNA levels and a decrease in oxidative stress after incubation with ethanol. In conclusion, leptin deficiency enhances sensitivity of rats to alcohol-induced steatohepatitis through hepatocyte-specific interaction of MT-1 and -2 and resultant exaggeration of oxidative stress in hepatocytes. These findings suggest that leptin resistance in hepatocytes is an important mechanism of alcohol-induced liver injury.
Influence of sildenafil on gastric sensorimotor function in humans
Authors: Sarnelli Giovanni , Sifrim Daniel , Janssens Jozef , Tack Jan
Published: October 2004

After a meal, the proximal stomach relaxes probably through the activation of nitrergic neurons in the gastric wall. Nitric oxide-induced smooth muscle relaxation involves activation of soluble guanylate cyclase, with cGMP production, which is then degradated by phosphodiesterase-5 (PDE-5). The aim of this study was to investigate the effect of sildenafil, a selective PDE-5 inhibitor, on fasting and postprandial proximal gastric volume and on gastric emptying rates in humans. A gastric barostat was used to study gastric compliance and perception to isobaric distension in healthy subjects before and after placebo ( n = 13) or sildenafil, 50 mg ( n = 15). In 10 healthy subjects, two gastric barostat studies were performed in randomized order to study the effect of placebo or sildenafil on postprandial gastric relaxation. Similarly, solid and liquid gastric emptying rates were studied in 12 healthy subjects. Sildenafil significantly increased fasting intragastric volume (141 ± 15 vs. 163 ± 15 ml, P < 0.05) and volumes of first perception. Sildenafil induced a higher and prolonged gastric relaxation either at 30 min (357 ± 38 vs. 253 ± 42 ml, P < 0.05) or 60 min (348 ± 49 vs. 247 ± 38 ml, P < 0.05) after the meal. Sildenafil did not alter solid half-emptying time but significantly delayed liquid emptying (43 ± 4 vs. 56 ± 4 min, P < 0.01). In conclusion, sildenafil significantly increases postprandial gastric volume and slows liquid emptying rate, confirming that meal-induced accommodation in humans involves the activation of a nitrergic pathway. The effect of sildenafil on gastric fundus suggests a therapeutic potential for phosphodiesterase inhibitors in patients with impaired gastric accommodation.
Brain angiotensin-converting enzyme activity and autonomic regulation in heart failure
Authors: Francis Joseph , Wei Shun-Guang , Weiss Robert M. , Felder Robert B.
Published: October 2004

Several recent studies suggest an important role for the brain renin-angiotensin system in the pathogenesis of heart failure. Angiotensin-converting enzyme (ACE) activity and binding of angiotensin type 1 (AT1) receptors, which mediate the central effects of ANG II, are increased in heart failure. The present study examined the relationship between brain ACE activity and the autonomic dysregulation characteristic of rats with congestive heart failure. Rats with heart failure (HF) induced by coronary artery ligation and sham-operated control (SHAM) rats were treated with chronic (28 days) third cerebral ventricle [intracerebroventricular (ICV)] or intraperitoneal (IP) infusion of a low dose of the ACE inhibitor enalaprilat (ENL) or vehicle (VEH). VEH-treated HF rats had increased sodium consumption, reduced urine sodium and urine volume, and increased sympathetic nerve activity with impaired baroreflex regulation. These responses were minimized or prevented by ICV ENL started 24 h after coronary ligation. IP ENL at the low dose used in these studies had no beneficial effects on HF rats. Neither IP nor ICV ENL had any substantial effect on the SHAM rats. The findings confirm a critically important contribution of the brain renin-angiotensin system to the pathophysiology of congestive heart failure.
Protective effect of IL-6 on alveolar epithelial cell death induced by hydrogen peroxide
Authors: Kida Hiroshi , Yoshida Mitsuhiro , Hoshino Shigenori , Inoue Koji , Yano Yukihiro , Yanagita Masahiko , Kumagai Toru , Osaki Tadashi , Tachibana Isao , Saeki Yukihiko , Kawase Ichiro
Published: October 2004

The goal of this study was to examine whether IL-6 could directly protect lung resident cells, especially alveolar epithelial cells, from reactive oxygen species (ROS)-induced cell death. ROS induced IL-6 gene expression in organotypic lung slices of wild-type (WT) mice. ROS also induced IL-6 gene expression in mouse primary lung fibroblasts, dose dependently. The organotypic lung slices of WT were more resistant to ROS-induced DNA fragmentation than those of IL-6-deficient (IL-6−/−) mice. WT resistance against ROS was abrogated by treatment with anti-IL-6 antibody. TdT-mediated dUTP nick end labeling stain and electron microscopy revealed that DNA fragmented cells in the IL-6−/− slice included alveolar epithelial cells and endothelial cells. In vitro studies demonstrated that IL-6 reduced ROS-induced A549 alveolar epithelial cell death. Together, these data suggest that IL-6 played an antioxidant role in the lung by protecting lung resident cells, especially alveolar epithelial cells, from ROS-induced cell death.
RhoA and Rho-kinase dependent and independent signals mediate TGF-β-induced pulmonary endothelial cytoskeletal reorganization and permeability
Authors: Clements Richard T. , Minnear Fred L. , Singer Harold A. , Keller Rebecca S. , Vincent Peter A.
Published: October 2004

Transforming growth factor (TGF)-β is a potent inflammatory mediator involved in acute lung injury. TGF-β directly increases pulmonary endothelial myosin light chain (MLC) phosphorylation, which is associated with increased endothelial stress fiber formation, gap formation, and protein permeability, all hallmarks of pulmonary endothelial responses during acute lung injury. We performed the following experiments in pulmonary endothelial monolayers to determine whether RhoA and Rho-kinase mediate these TGF-β-induced responses. TGF-β caused the sustained activation of RhoA 2 h posttreatment associated with increased MLC phosphorylation. Inhibition of either RhoA or Rho-kinase with either C3 exoenzyme or Y-27632 blocked MLC phosphorylation. In addition, both C3 and Y-27632 partially attenuated the maximal TGF-β-induced increase in permeability but did not affect the initial phase of compromised barrier integrity. Inhibition of Rho-kinase completely blocked the TGF-β-induced increase in the content of filamentous actin (F-actin) but only partially inhibited TGF-β-induced changes in actin reorganization. To assess the contribution of Rho-kinase in RhoA-mediated responses independent of additional TGF-β-induced signals, cells were infected with a constitutively active RhoA adenovirus (RhoAQ63L) with or without Y-27632. RhoAQ63L increased MLC phosphorylation, F-actin content, and permeability. Treatment with Y-27632 blocked these responses, suggesting that Rho-kinase mediates these RhoA-induced effects. Collectively, these data suggest the following: 1) the RhoA/Rho-kinase pathway is an important component of TGF-β-induced effects on endothelial MLC phosphorylation, cytoskeletal reorganization, and barrier integrity; and 2) additional signaling mechanisms independent of the RhoA/Rho-kinase signaling cascade contribute to TGF-β-induced changes in cytoskeletal organization and permeability.
Endotoxin-induced lung injury in mice: structural, functional, and biochemical responses
Authors: Rojas Mauricio , Woods Charles R. , Mora Ana L. , Xu Jianguo , Brigham Kenneth L.
Published: October 2004

Acute lung injury is usually a complication of sepsis, and endotoxin treatment of mice is a frequently used experimental model. To define this model and to clarify pathogenesis of the lung injury, we injected with 1 mg/kg endotoxin ip and measured pulmonary function, pulmonary edema, serum concentrations of cytokines and growth factors, and lung histology over 48 h. During the first 6 h, tidal volume and minute volume increased and respiratory frequency decreased. Serum concentrations of cytokines showed three patterns: 10 cytokines peaked at 2 h and declined rapidly, two peaked at 6 h and declined, and two had biphasic peaks at 2 and 24 h. Growth factors increased later and remained elevated longer. Both collagen and fibronectin were deposited in the lungs beginning within hours of endotoxin and resolving over 48 h. Histologically, lungs showed increased cellularity at 6 h with minimal persistent inflammation at 48 h. Lung water peaked at 6 h and gradually decreased over 48 h. We conclude that intraperitoneal administration of endotoxin to mice causes a transient systemic inflammatory response and transient lung injury and dysfunction. The response is characterized by successive waves of cytokine release into the circulation, early evidence of lung fibrogenesis, and prolonged increases in growth factors that may participate in lung repair.