bluuebunny/crossref_metadata_2025 huggingface dataset:
Endophthalmitis following cataract surgery in Sweden: national prospective survey 1999–2001
Authors: Wejde Gisela , Montan Per , Lundström Mats , Stenevi Ulf , Thorburn William
Published: February 2005

Purpose:  To investigate the epidemiology of postoperative endophthalmitis (POE) following cataract surgery in Sweden during a 3‐year period, using the framework of the Swedish National Cataract Register.

Methods:  Clinically presumed cases of POE were reported in a prospective survey involving all Swedish ophthalmic surgical units except one. Data on results of the intraocular culture and visual outcome after infection, as well as patient age and gender and various elements of the surgical procedure, were collected.

Results:  The nationwide incidence of POE was 0.0595%, representing 112 cases in 188 151 cataract operations. Gram‐positive bacteria were the predominant aetiology, with an 84.6% share of culture‐positive cases. A significantly decreased risk for POE was found for patients who had received prophylactic intracameral antibiotics (mainly cefuroxime) in comparison with those who had been treated with topical antibiotics only.

Conclusions:  The prevalence of POE after cataract surgery in Sweden is at the lower end of the spectrum of incidence currently reported in the developed world. The administration of intracameral antibiotics may have contributed to these results.
Total iris expulsion through a sutureless cataract incision due to vomiting
Authors: Slettedal Jon Klokk , Bragadóttir Ragnheiður
Published: February 2005

Purpose:  To present a case of isolated total iris expulsion through a self‐sealing cataract incision 2 weeks postoperatively due to vomiting.

Methods:  Ophthalmological examination included visual acuity assessment, tonometry, slit‐lamp examination, fundus ophthalmoscopy and ultrasound examination.

Results:  A 65‐year‐old woman experienced sudden visual loss during an episode of vigorous vomiting 2 weeks after uncomplicated phacoemulsification cataract surgery with a sutureless corneal incision. Clinical examination showed a dense anterior chamber haemorrhage. When the blood had cleared, isolated total aniridia was seen.

Conclusions:  This is the first reported case of aniridia after cataract surgery due to vomiting.
Strategies for improving the diagnostic specificity of the frequency doubling perimeter
Authors: Heeg Govert P. , Stoutenbeek Remco , Jansonius Nomdo M.
Published: February 2005

Purpose:  To evaluate various strategies designed to improve the specificity of the interpretation of results obtained with the frequency doubling technology perimeter (FDT) used in the full‐threshold mode.

Methods:  Three different strategies were compared using data from 452 glaucoma patients and 237 healthy subjects: combining several FDT parameters from a single test, combining the FDT test with a GDx test, and confirming an abnormal FDT test result with a repeat test.

Results:  Confirming an abnormal FDT test result with a repeat test yielded a specificity increase of 0.10, from 0.80 to 0.90, at the expense of some loss of sensitivity for early but not for moderate or severe glaucoma. Combining several FDT parameters from a single test and combining FDT with GDx did not yield any noticeable increase in diagnostic performance.

Conclusions:  A modest increase in FDT diagnostic performance can be obtained by the confirmation of an abnormal test result with a repeat test.
Das klinische Spektrum der Dermatomyositis
Authors: Kaufmann Julia , Hunzelmann Nicolas , Genth Ekkehard , Krieg Thomas
Published: February 2005

Die Dermatomyositis weist eine große klinische Heterogenität auf. Es existieren eine Reihe von Klassifikationen, die sich auf die Beteiligung der Muskulatur, auf das Vorkommen von Autoantikörpern und das Vorhandensein zusätzlicher Symptome anderer Kollagenosen stützen. Ätiologisch wesentlich sind vorangegangene virale Infektionen, sowie das Entstehen von Tumoren, die auch erst nach Auftreten der Dermatomyositis klinisch manifest werden können. Genaue, auch wiederholte Untersuchungen sind daher bei diesen Patienten ratsam. Eine exakte Feststellung der Organbeteiligung, sowie die Charakterisierung bestimmter zirkulierender Antikörper sind wichtige Voraussetzungen für das Erstellen einer Prognose für die Patienten. Die Dermatomyositis macht oft eine intensive, hochdosierte Therapie mit Glukokortikoiden, sowie immunsuppressiven Medikamenten oder Immunglobinen notwendig. Diese muß dem Verlauf der Erkrankung individuell angepaßt sein.
Nonlinear vibrations of suspended cables—Part I: Modeling and analysis
Authors: Rega Giuseppe
Published: February 2005

This review article is the first of three parts of a Special Issue dealing with finite-amplitude oscillations of elastic suspended cables. This part is concerned with system modeling and methods of analysis. After shortly reporting on cable historical literature and identifying the topic and scope of the review, the article begins with a presentation of the mechanical system and of the ensuing mathematical models. Continuum equations of cable finite motion are formulated, their linearized version is reported, and nonlinear discretized models for the analysis of 2D or 3D vibration problems are discussed. Approximate methods for asymptotic analysis of either single or multi-degree-of-freedom models of small-sag cables are addressed, as well as asymptotic models operating directly on the original partial differential equations. Numerical tools and geometrical techniques from dynamical systems theory are illustrated with reference to the single-degree-of-freedom model of cable, reporting on measures for diagnosis of nonlinear and chaotic response, as well as on techniques for local and global bifurcation analysis. The paper ends with a discussion on the main features and problems encountered in nonlinear experimental analysis of vibrating suspended cables. This review article cites 226 references.
Nonlinear vibrations of suspended cables—Part II: Deterministic phenomena
Authors: Rega Giuseppe
Published: February 2005

The present work is concerned with deterministic nonlinear phenomena arising in the finite-amplitude dynamics of elastic suspended cables. The underlying theoretical framework has been addressed in Part I of this Special Issue, where the mechanical system and its mathematical modeling have been presented, and different techniques for the analysis of nonlinear dynamics have been illustrated with reference to the suspended cable. Herein, we discuss the main features of system regular and complex response, and the associated bifurcational behavior. Nonlinear phenomena are considered separately for single-degree-of-freedom and multidegree-of-freedom cable models, by distinguishing between theoretical and experimental results and comparing them with each other. Regular and nonregular vibrations are considered either in the absence of internal resonance or under various internal/external, and possibly simultaneous, resonance conditions. The most robust classes of steady periodic motions, the relevant response scenarios in control parameter space, and the main features of multimodal interaction phenomena are summarized. Bifurcation and chaos phenomena are discussed for the single-dof model by analyzing the local and global features of steady nonregular dynamics. For the experimental model, the most meaningful scenarios of transition to chaos are illustrated, together with the properties of the ensuing quasiperiodic and chaotic attractors. Finally, the important issues of determining system dimensionality and identifying properly reduced-order theoretical models of cable are addressed. There are 185 references listed in this review article.
Nonlinear vibrations of suspended cables—Part III: Random excitation and interaction with fluid flow
Authors: Ibrahim Raouf A
Published: February 2005

This review article deals with the random excitation of nonlinear strings and suspended cables in air and fluid flow. For strings and 1D cables, the system dynamics is governed by different forms of Duffing oscillator. A brief review is devoted to the stochastic excitation of a Duffing oscillator. Under random excitation, this oscillator may or may not possess multiple solutions depending on the excitation bandwidth and level. One may be interested in estimating response statistics, first passage problem, and power spectral density. Particular attention is given to the complex response phenomena associated with increasing the spectral density level of excitation. The numerical results of the problem of nonlinear modal interaction in suspended cables will be discussed in the neighborhood of multiple internal resonance conditions. For a unimodal response, the linear theory fails to predict nonzero mean response and underestimates the mean square response under white noise excitation. Complex response phenomena such as “on-off” intermittency, energy transfer, and stochastic bifurcation are reviewed. The dynamic behavior of suspended cables in still air is different from that in flowing fluid or severe wind current due to the action of vortices, fluid normal forces, added fluid inertia force, and fluid drag force. Aeolian and galloping vibration of suspended cables in air and their dynamics in fluid flow are discussed, together with the influence of dynamic tension. In the absence of external excitation, the action of fluid forces induces vibration to the cable. The dynamics of cables subjected to steady and random fluid flow is reviewed for mooring systems. Depending on the flow speed, the cable may experience divergence or flutter similar to the case of aeroelastic structures. While the deterministic theory of strings and cables has reached an advanced stage, the reader will realize that these systems need further investigations under random excitations. There are 297 references cited in this review article.
Genomic Analysis of Anaerobic Respiration in the ArchaeonHalobacteriumsp. Strain NRC-1: Dimethyl Sulfoxide and TrimethylamineN-Oxide as Terminal Electron Acceptors
Authors: Müller Jochen A. , DasSarma Shiladitya
Published: February 2005

We have investigated anaerobic respiration of the archaeal model organismHalobacteriumsp. strain NRC-1 by using phenotypic and genetic analysis, bioinformatics, and transcriptome analysis. NRC-1 was found to grow on either dimethyl sulfoxide (DMSO) or trimethylamineN-oxide (TMAO) as the sole terminal electron acceptor, with a doubling time of 1 day. An operon,dmsREABCD, encoding a putative regulatory protein, DmsR, a molybdopterin oxidoreductase of the DMSO reductase family (DmsEABC), and a molecular chaperone (DmsD) was identified by bioinformatics and confirmed as a transcriptional unit by reverse transcriptase PCR analysis.dmsR,dmsA, anddmsDin-frame deletion mutants were individually constructed. Phenotypic analysis demonstrated thatdmsR,dmsA, anddmsDare required for anaerobic respiration on DMSO and TMAO. The requirement fordmsR, whose predicted product contains a DNA-binding domain similar to that of the Bat family of activators (COG3413), indicated that it functions as an activator. A cysteine-rich domain was found in thedmsRgene, which may be involved in oxygen sensing. Microarray analysis using a whole-genome 60-mer oligonucleotide array showed that thedmsoperon is induced during anaerobic respiration. Comparison ofdmsR+and ΔdmsRstrains by use of microarrays showed that the induction of thedmsEABCDoperon is dependent on a functionaldmsRgene, consistent with its action as a transcriptional activator. Our results clearly establish the genes required for anaerobic respiration using DMSO and TMAO in an archaeon for the first time.
Common Evolutionary Origin for the Unstable Virulence Plasmid pMUM Found in Geographically Diverse Strains ofMycobacterium ulcerans
Authors: Stinear Timothy P. , Hong Hui , Frigui Wafa , Pryor Melinda J. , Brosch Roland , Garnier Thierry , Leadlay Peter F. , Cole Stewart T.
Published: February 2005

The 174-kb virulence plasmid pMUM001 inMycobacterium ulceransepidemic strain Agy99 harbors three very large and homologous genes that encode giant polyketide synthases (PKS) responsible for the synthesis of the lipid toxin mycolactone. Deeper investigation ofM. ulceransAgy99 resulted in identification of two types of spontaneous deletion variants of pMUM001 within a population of cells that also contained the intact plasmid. These variants arose from recombination between two 8-kb sections of the same plasmid sequence, resulting in the loss of a 65-kb region bearing two of the three mycolactone PKS genes. Investigation of nine diverseM. ulceransstrains by using PCR and Southern hybridization for eight pMUM001 gene sequences confirmed the presence of pMUM001-like elements (collectively called pMUM) in allM. ulceransstrains. Physical mapping of these plasmids revealed that likeM. ulceransAgy99, three strains had undergone major deletions in their mycolactone PKS loci. Online liquid chromatography-sequential mass spectrometry analysis of lipid extracts confirmed that strains with PKS deletions were unable to produce mycolactone or any related cometabolites. Interstrain comparisons of the plasmid gene sequences revealed greater than 98% nucleotide identity, and the phylogeny inferred from these sequences closely mimicked the phylogeny from a previous multilocus sequence typing study in which chromosomally encoded loci were used, a result that is consistent with the hypothesis thatM. ulceransdiverged from the closely related organismMycobacterium marinumby acquiring pMUM. Our results suggest that pMUM is a defining characteristic ofM. ulceransbut that in the absence of purifying selection, deletion of plasmid sequences and a corresponding loss of mycolactone production readily arise.
A Chimeric N-Terminal
Escherichia coli
-C-Terminal
Rhodobacter sphaeroides
FliG Rotor Protein Supports Bidirectional
E. coli
Flagellar Rotation and Chemotaxis
Authors: Morehouse Karen A. , Goodfellow Ian G. , Sockett R. Elizabeth
Published: February 2005

Flagellate bacteria such as
Escherichia coli
and
Salmonella enterica
serovar Typhimurium typically express 5 to 12 flagellar filaments over their cell surface that rotate in clockwise (CW) and counterclockwise directions. These bacteria modulate their swimming direction towards favorable environments by biasing the direction of flagellar rotation in response to various stimuli. In contrast,
Rhodobacter sphaeroides
expresses a single subpolar flagellum that rotates only CW and responds tactically by a series of biased stops and starts. Rotor protein FliG transiently links the MotAB stators to the rotor, to power rotation and also has an essential function in flagellar export. In this study, we sought to determine whether the FliG protein confers directionality on flagellar motors by testing the functional properties of
R. sphaeroides
FliG and a chimeric FliG protein, EcRsFliG (N-terminal and central domains of
E. coli
FliG fused to an
R. sphaeroides
FliG C terminus), in an
E. coli
FliG null background. The EcRsFliG chimera supported flagellar synthesis and bidirectional rotation; bacteria swam and tumbled in a manner qualitatively similar to that of the wild type and showed chemotaxis to amino acids. Thus, the FliG C terminus alone does not confer the unidirectional stop-start character of the
R. sphaeroides
flagellar motor, and its conformation continues to support tactic, switch-protein interactions in a bidirectional motor, despite its evolutionary history in a bacterium with a unidirectional motor.
The Core Lipopolysaccharide ofEscherichia coliIs a Ligand for the Dendritic-Cell-Specific Intercellular Adhesion Molecule Nonintegrin CD209 Receptor
Authors: Klena John , Zhang Pei , Schwartz Olivier , Hull Sheila , Chen Tie
Published: February 2005

The dendritic-cell-specific intercellular adhesion molecule nonintegrin (DC-SIGN) CD209 is a receptor forEscherichia coliK-12 that promotes bacterial adherence and phagocytosis. However, the ligand ofE. colifor DC-SIGN has not yet been identified. In this study, we found that DC-SIGN did not mediate the phagocytosis of several pathogenic strains ofE. coli, including enteropathogenicE. coli, enterohemorrhagicE. coli, enterotoxigenicE. coli, and uropathogenicE. coli, in dendritic cells or HeLa cells expressing human DC-SIGN antigen. However, we showed that an outer core lipopolysaccharide (LPS) (rough) mutant, unlike an inner core LPS (deep rough) mutant or O-antigen-expressing recombinant ofE. coliK-12 was phagocytosed. These results demonstrate that the host cells expressing DC-SIGN can phagocytoseE. coliin part by interacting with the complete core region of the LPS molecule. These results provide a mechanism for how O antigen acts as an antiphagocytic factor.
Cytoplasmic Control of Premature Activation of a Secreted Protease Zymogen: Deletion of Staphostatin B (SspC) in
Staphylococcus aureus
8325-4 Yields a Profound Pleiotropic Phenotype
Authors: Shaw Lindsey N. , Golonka Ewa , Szmyd Grzegorz , Foster Simon J. , Travis James , Potempa Jan
Published: February 2005

The cytoplasmic protein SspC of
Staphylococcus aureus
, referred to as staphostatin B, is a very specific, tightly binding inhibitor of the secreted protease staphopain B (SspB). SspC is hypothesized to protect intracellular proteins against proteolytic damage by prematurely folded and activated staphopain B (M. Rzychon, A. Sabat, K. Kosowska, J. Potempa, and A. Dubin, Mol. Microbiol.
49:
1051-1066, 2003). Here we provide evidence that elimination of intracellular staphopain B activity is indeed the function of SspC. An isogenic
sspC
mutant of
S. aureus
8325-4 exhibits a wide range of striking pleiotropic alterations in phenotype, which distinguish it from the parent. These changes include a defect in growth, a less structured peptidoglycan layer within the cell envelope, severely decreased autolytic activity, resistance to lysis by
S. aureus
phages, extensively diminished sensitivity to lysis by lysostaphin, the ability to form a biofilm, and a total lack of extracellular proteins secreted into the growth media. The same phenotype was also engineered by introduction of
sspB
into an 8325-4
sspBC
mutant. In contrast,
sspC
inactivation in the SH1000 strain did not yield any significant changes in the mutant phenotype, apparently due to strongly reduced expression of
sspB
in the sigma B-positive background. The exact pathway by which these diverse aberrations are exerted in 8325-4 is unknown, but it is apparent that a very small amount of staphopain B (less than 20 ng per 200 μg of cell proteins) is sufficient to bring about these widespread changes. It is proposed that the effects observed are modulated through the proteolytic degradation of several cytoplasmic proteins within cells lacking the inhibitor. Seemingly, some of these proteins may play a role in protein secretion; hence, their proteolytic inactivation by SspB has pleiotropic effects on the SspC-deficient mutant.
Cyclic Diguanylate Is a Ubiquitous Signaling Molecule in Bacteria: Insights into Biochemistry of the GGDEF Protein Domain
Authors: Ryjenkov Dmitri A. , Tarutina Marina , Moskvin Oleg V. , Gomelsky Mark
Published: February 2005

Proteins containing GGDEF domains are encoded in the majority of sequenced bacterial genomes. In several species, these proteins have been implicated in biosynthesis of exopolysaccharides, formation of biofilms, establishment of a sessile lifestyle, surface motility, and regulation of gene expression. However, biochemical activities of only a few GGDEF domain proteins have been tested. These proteins were shown to be involved in either synthesis or hydrolysis of cyclic-bis(3′→5′) dimeric GMP (c-di-GMP) or in hydrolysis of cyclic AMP. To investigate specificity of the GGDEF domains in
Bacteria
, six GGDEF domain-encoding genes from randomly chosen representatives of diverse branches of the bacterial phylogenetic tree, i.e.,
Thermotoga
,
Deinococcus-Thermus
,
Cyanobacteria
, spirochetes, and α and γ divisions of the
Proteobacteria
, were cloned and overexpressed. All recombinant proteins were purified and found to possess diguanylate cyclase (DGC) activity involved in c-di-GMP synthesis. The individual GGDEF domains from two proteins were overexpressed, purified, and shown to possess a low level of DGC activity. The oligomeric states of full-length proteins and individual GGDEF domains were similar. This suggests that GGDEF domains are sufficient to encode DGC activity; however, enzymatic activity is highly regulated by the adjacent sensory protein domains. It is shown that DGC activity of the GGDEF domain protein Rrp1 from
Borrelia burgdorferi
is strictly dependent on phosphorylation status of its input receiver domain. This study establishes that majority of GGDEF domain proteins are c-di-GMP specific, that c-di-GMP synthesis is a wide-spread phenomenon in
Bacteria
, and that it is highly regulated.
Polyphosphate:AMP Phosphotransferase as a Polyphosphate-Dependent Nucleoside Monophosphate Kinase in
Acinetobacter johnsonii
210A
Authors: Shiba Toshikazu , Itoh Hiromichi , Kameda Atsushi , Kobayashi Keiju , Kawazoe Yumi , Noguchi Toshitada
Published: February 2005

We have cloned the gene for polyphosphate:AMP phosphotransferase (PAP), the enzyme that catalyzes phosphorylation of AMP to ADP at the expense of polyphosphate [poly(P)] in
Acinetobacter johnsonii
210A. A genomic DNA library was constructed in
Escherichia coli
, and crude lysates of about 6,000 clones were screened for PAP activity. PAP activity was evaluated by measuring ATP produced by the coupled reactions of PAP and purified
E. coli
poly(P) kinases (PPKs). In this coupled reaction, PAP produces ADP from poly(P) and AMP, and the resulting ADP is converted to ATP by PPK. The isolated
pap
gene (1,428 bp) encodes a protein of 475 amino acids with a molecular mass of 55.8 kDa. The C-terminal region of PAP is highly homologous with PPK2 homologs isolated from
Pseudomonas aeruginosa
PAO1. Two putative phosphate-binding motifs (P-loops) were also identified. The purified PAP enzyme had not only strong PAP activity but also poly(P)-dependent nucleoside monophosphate kinase activity, by which it converted ribonucleoside monophosphates and deoxyribonucleoside monophosphates to ribonucleoside diphosphates and deoxyribonucleoside diphosphates, respectively. The activity for AMP was about 10 times greater than that for GMP and 770 and about 1,100 times greater than that for UMP and CMP.
Transcriptome of
Treponema pallidum
: Gene Expression Profile during Experimental Rabbit Infection
Authors: Šmajs David , McKevitt Matthew , Howell Jerrilyn K. , Norris Steven J. , Cai Wei-Wen , Palzkill Timothy , Weinstock George M.
Published: February 2005

RNA transcript levels in the syphilis spirochete
Treponema pallidum
subsp.
pallidum
(Nichols) isolated from experimentally infected rabbits were determined by the use of DNA microarray technology. This characterization of the
T. pallidum
transcriptome during experimental infection provides further insight into the importance of gene expression levels for the survival and pathogenesis of this bacterium.
Increased efflux of glutathione conjugate in acutely diabetic cardiomyocytes
Authors: Ghosh Sanjoy , Ting Simon , Lau Howard , Pulinilkunnil Thomas , An Ding , Qi Dake , Abrahani Mohammed A , Rodrigues Brian
Published: February 2005

In diabetes, cell death and resultant cardiomyopathy have been linked to oxidative stress and depletion of antioxidants like glutathione (GSH). Although the de novo synthesis and recycling of GSH have been extensively studied in the chronically diabetic heart, their contribution in modulating cardiac oxidative stress in acute diabetes has been largely ignored. Additionally, the possible contribution of cellular efflux in regulating GSH levels during diabetes is unknown. We used streptozotocin to make Wistar rats acutely diabetic and after 4 days examined the different processes that regulate cardiac GSH. Reduction in myocyte GSH in diabetic rats was accompanied by increased oxidative stress, excessive reactive oxygen species, and an elevated apoptotic cell death. The effect on GSH was not associated with any change in either synthesis or recycling, as both γ-glutamylcysteine synthetase gene expression (responsible for bio syn thesis) and glutathione reductase activity (involved with GSH recycling) remained unchanged. However, gene expression of multidrug resistance protein 1, a transporter implicated in effluxing GSH during oxidative stress, was elevated. GSH conjugate efflux mediated by multidrug resistance protein 1 also increased in diabetic cardiomyocytes, an effect that was blocked using MK-571, a specific inhibitor of this transporter. As MK-571 also decreased oxidative stress in diabetic cardiomyocytes, an important role can be proposed for this transporter in GSH and reactive oxygen species homeostasis in the acutely diabetic heart. Key words: cardiomyocytes, apoptosis, multidrug resistance protein, reactive oxygen species.
The expression and function of a group VIA calcium-independent phospholipase A2(iPLA2β) in β-cells
Authors: Turk John , Ramanadham Sasanka
Published: February 2005

Many cells express a Group VIA phospholipase A2,designated iPLA2β, that does not require calcium for activation, is stimulated by ATP, and is sensitive to inhibition by a bromoenol lactone suicide substrate (BEL). Studies in various cell systems have led to the suggestion that iPLA2β has a role in phospholipid remodeling, signal transduction, cell proliferation, and apoptosis. We have found that pancreatic islets, β-cells, and glucose-responsive insulinoma cells express an iPLA2β that participates in glucose-stimulated insulin secretion but is not involved in membrane phos pho lipid remodeling. Additionally, recent studies reveal that iPLA2β is involved in pathways that contribute to β-cell proliferation and apoptosis, and that various phospholipid-derived mediators are involved in these processes. Detailed characterization of the enzyme suggests that the β-cells express multiple isoforms of iPLA2β, and we hypothesize that these participate in different cellular functions.Key words: signalling, apoptosis, isoforms, mass spectrometry.
Investigation of the mechanism of nicotine-induced relaxation on the sheep sphincter of Oddi
Authors: Bagcivan Ihsan , Kaya Tijen , Turan Mustafa , Goktas Selçuk , Demirel Yeltekin , Gursoy Sinan
Published: February 2005

Possible mechanisms for nicotine-induced relaxation were investigated in the isolated sheep's sphincter of Oddi. Sheep's sphincter of Oddi rings were mounted in tissue bath with modified Krebs-Henseleit solution and aerated with 95% oxygen and 5% carbon dioxide. Tension was measured with isometric force transducers, and muscle relaxation was expressed as percent decrease of precontraction induced by carbachol. Nicotine (1 × 105 to 3 × 103 mol/L) produced concentration-dependent relaxation on sphincter of Oddi precontracted by carbachol (106 mol/L). Nicotine-induced relaxation was 72.8 ± 4.2% of precontraction with carbachol (106 mol/L) (mean pD2 value, 3.76 ± 0.05 mol/L). Nicotine-induced relaxation was not affected by N(w)-nitro L-arginine methyl ester (L-NAME) (3 × 105 mol/L), methylene blue (105 mol/L), indomethacin (105 mol/L), hexamethonium (105 mol/L), glibenclamide (105 mol/L), 4-aminopyridine (103 mol/L), tetraethylammonium (3 × 104 mol/L), clotrimazole (106 mol/L), 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) (106 mol/L), and anthracene-9-carboxylate (9-AC) (106 mol/L), but potentiated by bupivacain (105 mol/L). A calcium-antagonizing effect of nicotine was not observed. The results suggest that nicotine-induced relaxation of the sheep's sphincter of Oddi is not mediated by the release of prostaglandins, nitric oxide (NO), or a related substance; by the activation of potassium channels or chloride channels; or by the stimulation of nicotinic cholinoceptors. Potentiation of the nicotine-induced relaxation by bupivacain indicates that blockade of sodium channels may play a role in this relaxation.Key words: nicotine, sphincter of Oddi, relaxation.
Endomorphins, endogenous opioid peptides, induce apoptosis in human leukemia HL-60 cells
Authors: Lin Xin , Chen Qiang , Xue Li-Ying , Ma Xiao-Jun , Wang Rui
Published: February 2005

Opioids play a role in the apoptosis machinery. We studied the induction of apoptosis in endomorphin 1 (EM1) and endomorphin 2 (EM2), 2 newly isolated endogenous µ-opioid receptor agonists. These endomorphins were able to reduce the viability of cultured HL-60 cells. The antiproliferative properties of endomorphins appeared to be attributable to their induction of apoptotic cell death as determined by ultrastructural change, internucleosomal DNA fragmentation, and increased proportion of the subdiploid cell population. To elucidate molecular events in the apoptosis, protein expressions of Bcl-2, Bax, Fas, and FasL were measured by western blotting using specific antibodies in HL-60 cells. The level of Bcl-2 indicated down-regulation, but the Bax, Fas, and FasL expression showed up-regulation as compared with the untreated control cells. These data support the idea that endomorphins induce apoptosis in HL-60 cells through the activation of the Bcl-2–Bax and the Fas–FasL pathway. We suggest that endomorphins may play an important role in the regulation of tumor cell death.Key words: endomorphins, HL-60 cell, apoptosis, Bcl-2, Fas.
Potassium channel diversity within the muscular components of the feline lower esophageal sphincter
Authors: Salapatek Anne Marie F , Ji Junzhi , Muinuddin Ahmad , Diamant Nicholas E
Published: February 2005

We hypothesized that regional differences in electrophysiological properties exist within the musculature of the feline lower esophageal sphincter (LES) and that they may potentially contribute to functional asymmetry within the LES. Freshly isolated esophageal smooth muscle cells (SMCs) from the circular muscle and sling regions within the LES were studied under a patch clamp. The resting membrane potential (RMP) of the circular SMCs was significantly more depolarized than was the RMP of the sling SMCs, resulting from a higher Na+and Cl–permeability in circular muscle than in sling muscle. Large conductance Ca2+-activated K+(BKCa) set the RMP at both levels, since specific BKCainhibitors caused depolarization; however, BKCadensity was greatest in the circular region. A significant portion of the outward current was due to non-BKCa, especially in sling muscle, and likely delayed rectifier K+channels (KDR). There was a large reduction in outward current with 4-aminopyridine (4-AP) in sling muscle, while BKCablockers had a limited effect on the voltage-activated outward current in sling muscle. Differences in BKCa:KDRchannel ratios were also manifest by a leftward shift in the voltage-dependent activation curve in circular cells compared to sling cells. The electrophysiological differences seen between the circular and sling muscles provide a basis for their different contributions to LES activities such as resting tone and neurotransmitter responsiveness, and in turn could impart asymmetric drug responses and provide specific therapeutic targets.Key words: esophagus, esophageal motility, gastroesophageal reflux, KCa, KDR, LES tone.
Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences
Authors: Faine Luciane A , Diniz Yeda S , Galhardi Cristiano M , Rodrigues Hosana G , Burneiko Regina C , Santana Lea S , Cicogna Antonio C , Novelli Ethel L.B
Published: February 2005

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180–200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg·day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.Key words: dietary restriction, olive oil, lipid profile, cardiac tissue, antioxidant enzymes.
Long-term effects of the PPARγ activator pioglitazone on cardiac inflammation in stroke-prone spontaneously hypertensive rats
Authors: Diep Quy N , Amiri Farhad , Benkirane Karim , Paradis Pierre , Schiffrin Ernesto L
Published: February 2005

We investigated the long-term effects of the thiazolidinedione PPARγ activator pioglitazone on cardiac inflammation in stroke-prone spontaneously hypertensive rats (SHRSP), a model of malignant of hypertension. Six-week-old SHRSP were treated with pioglitazone (10 mg/kg per day p.o.) for 20 weeks. The rise in systolic blood pressure (SBP) in SHRSP was only transiently and slightly attenuated by pioglitazone (P < 0.05). On one hand, cardiac hypertrophy was little affected by the pioglitazone treatment, and there was only a reduction of subepicardial interstitial fibrosis. On the other hand, left ventricular NFκB and AP-1 binding activities, the expression of TNFα, and the adhesion of molecule PECAM were significantly decreased by pioglitazone treatment. Expression of the pro-apoptotic proteins p53 and bax was significantly increased by pioglitazone. Thus, pioglitazone-attenuated cardiac inflammation in SHRSP had little effect on BP or cardiac hypertrophy. PPARγ activation may play a preventive cardiovascular role by offsetting the cardiac inflammatory response as demonstrated in this genetic model of malignant hypertension.Key words: hypertension, heart, inflammation, NFκB, adhesion molecules.
Potential role ofN-myristoyltransferase in pathogenic conditions
Authors: Sharma Rajendra K
Published: February 2005

N-Myristoyltransferase (NMT) is the enzyme that catalyzes the covalent transfer of myristic acid to the N-terminal glycine residue of a protein substrate. In this review article, I summarize that NMT may have a potential role in cardiac muscle in the experimentally induced ischemia–reperfusion rat model and also in the streptozotoein-induced diabetic rat. Both the expression and activity of NMT were increased by ischemia–reperfusion. Immunohistochemical studies showed cytosolic localization of NMT in normal rat heart and predominant nuclear localization after ischemia followed by reperfusion. However, the localization of NMT is reversed by treatment with a calpain inhibitor (ALLM N-Ac-Leu-Leu-methioninal). During ischemia–reperfusion, the degradation of c-Src, which is a substrate of NMT, was observed. These findings suggested that the Src signaling may be impaired in ischemia–reperfusion owing to the altered localization of NMT from cytoplasm to nucleus. Streptozotocin-induced diabetes (an animal model for insulin-dependent diabetes mellitus) resulted in a 2.0-fold increase in rat liver NMT activity as compared with control animals. In obese (fa/fa) Zucker rats (an animal model for non-insulin-dependent diabetes mellitus), there was an ~4.7-fold lower liver particulate NMT activity as compared with control lean rat livers. Administration of sodium orthovanadate to the diabetic rats normalized liver NMT activity. These results would indicate that rat liver particulate NMT activity appears to be inversely proportional to the level of plasma insulin, implicating insulin in the control of N-myristoylation. These are the first studies demonstrating the role of NMT in the pathogenesis of ischemia–reperfusion and diabetes mellitus. These conditions remain an important area of investigation.Key words: N-myristoyltransferase, ischemic heart, calpains, diabetes, vanadate.
Altered inotropic reactivity in diabetic rabbit right ventricular myocardium
Authors: Lee J Rex , Zhang Xin-Jian , Lin Bor-Kang , Reigel Charles E , Tenner, Jr. Thomas E
Published: February 2005

Alloxan monohydrate was used to induce diabetes in rabbits, which were maintained for a 3-month period with or without daily insulin replacement along with age-matched controls. Isolated right ventricular myocardial strips were used to generate dose–response curves to isoproterenol, forskolin, and Bay K 8644. Basal developed force was significantly elevated in diabetic ventricular strips. While isoproterenol acted as a full inotropic agonist, diabetic preparations revealed a consistent but insignificant decrease in the maximum developed force. While both sensitivity to isoproterenol and β-adrenoceptor density were decreased in preparations from diabetic rabbits, there was no associated increase in circulating plasma catecholamines. In contrast, forskolin and Bay K 8644 were partial agonists in control preparations but full inotropic agonists in diabetic preparations, demonstrating significant increases in maximum developed force. This hyperresponsiveness was not associated with altered calcium channel density. Finally, insulin replacement reduced or prevented all diabetic-related changes. These data indicate that the hyperresponsiveness to forskolin and Bay K 8644 represents an altered utilization of intracellular calcium in the diabetic rabbit, converting them into full agonists similar to isoproterenol. The decrease in sensitivity to isoproterenol correlated with a decrease in β-adrenoceptor density but not elevated circulating catecholamines as previously observed in diabetic rats.Key words: experimental diabetes, β-adrenoceptor density, inotropic state, hyperresponsiveness, subsensitivity, calcium utilization.
Conversion of renin substrate tetradecapeptide to angiotensin II by rat MAB elastase-2
Authors: Santos Carlos F , Greene Andrew S , Salgado Maria Cristina O , Oliveira Eduardo B
Published: February 2005

A new approach for the purification of rat mesenteric arterial bed (MAB) elastase-2 has been developed using the chromogenic substrates N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide and N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide to monitor the enzymatic activity during various stages of purification. The purified enzyme was evaluated in the presence of various inhibitors and confirmed to have angiotensin (Ang) II-forming ability. The active site-directed inhibitor acetyl-Ala-Ala-Pro-Leu-chloromethylketone (100 µmol·L-1), described for human pancreatic elastase-2, abolished the enzymatic activity, confirming that the enzyme is an elastase-2. Chymostatin (100 µmol·L-1), an inhibitor regarded as selective for chymases, also showed a remarkable inhibitory effect (94%), whereas captopril (100 µmol·L-1) had no effect at all on the Ang II-forming activity. The Ang II precursor renin substrate tetradecapeptide (RS-14P) was converted into Ang II by the rat MAB elastase-2 with the following kinetic constants: Km= 124 ± 21 µmol·L-1; Kcat= 629 min-1; catalytic efficiency (Kcat/Km) = 5.1 min-1µ(mol/L)-1. In conclusion, the strategy for the purification of rat MAB elastase-2 with the chromogenic substrates proved to be simple, rapid, accurate, and highly reproducible; therefore, it can be reliably and conveniently used to routinely purify this enzyme. The kinetic parameters for the formation of Ang II from RS-14P by rat MAB elastase-2 emphasize differences in substrate specificity between this and other Ang II-forming enzymes.Key words: N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide, elastase-2, angiotensin II, renin substrate tetradecapeptide.
Effective control of glycemic status and toxicity in Zucker diabetic fatty rats with an orally administered vanadate compound
Authors: Clark Tod A , Edel Andrea L , Heyliger Clayton E , Pierce Grant N
Published: February 2005

A novel black tea decoction containing vanadate has successfully replaced insulin in a rat model of insulin-dependent diabetes but is untested in non-insulin-dependent diabetic animals. A tea-vanadate decoction (TV) containing 30 or 40 mg sodium orthovanadate was administered by oral gavage to two groups of Zucker diabetic fatty rats and a conventional water vehicle containing 30 or 40 mg of sodium orthovanadate to two others. In the latter group receiving the 30-mg dose, vanadate induced diarrhea in 50% of the rats and death in 10%. In contrast, TV-treated rats had no incidence of diarrhea and no deaths. Symptoms were more severe in both groups with higher vanadate doses, so these were discontinued. After ~16 weeks, the level of vanadium in plasma and tissue extracts was negligible in a further group of untreated rats but highly elevated after vanadate treatment. Vanadium levels were not significantly different between the TV-treated diabetic rats and the diabetic rats given vanadate in a water vehicle. Over the 115 days of the study, blood glucose levels increased from ~17 to 25 mmol/L in untreated diabetic rats. This was effectively lowered (to <10 mmol/L) by TV treatment. Fasting blood glucose levels were 5, 7, and 20 mmol/L in control (nondiabetic, untreated), TV-treated and untreated diabetic rats, respectively. Rats required treatment with TV for only ~50% of the days in the study. Increase in body mass during the study was significantly lower in untreated diabetic rats (despite higher food intake) than the other groups. Body mass gain and food intake were normal in TV-treated rats. Water intake was 28 mL/rat daily in control rats, 130 mL/rat daily in untreated diabetic rats, and 52 mL/rat daily in TV-treated diabetic rats. Plasma creatinine and aspartate aminotransferase levels were significantly depressed in untreated diabetic rats, and TV treatment normalized this. Our results demonstrate that a novel oral therapy containing black tea and vanadate possesses a striking capacity to regulate glucose and attenuates complications in a rat model of type II diabetes. Key words: diabetes mellitus, tea, glycemia, type II diabetes.
Transport of endogenous nucleosides in guinea pig heart
Authors: Dekanski D , Piperski V , Tasić J , Marković I D , Jokanović M , Stukalov P , Mitrović D M
Published: February 2005

The purpose of this study was to investigate the characteristics of transport of endogenous nucleosides into cardiac tissue from coronary circulation. The study was performed on the isolated perfused guinea pig heart, using the rapid paired tracers single-pass technique. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of adenosine, deoxyadenosine, thymidine, uridine, and cytidine were determined. The cellular uptake of adenosine was significantly higher than the cellular uptake of other studied nucleosides. To elucidate the mechanisms of nucleoside transport, competition studies were performed and the influence of S-(p-nitrobenzyl)-6-thioinosine (NBTI) and sodium ion absence on Umax and Utot was investigated. Self- and cross-inhibition studies indicated the saturable mechanism of nucleosides transport into cardiac tissue and the involvement of different transport mechanisms for purine and pyrimidine nucleosides. The study also showed that both equilibrative-sensitive (es) and sodium-dependent transport were responsible for adenosine and thymidine cellular uptake.Key words: nucleosides, transport, heart.
Cytochrome p450 enzymes and cardiovascular disease
Authors: Hunter Arwen L , Cruz Rani P , Cheyne Bo M , McManus Bruce M , Granville David J
Published: February 2005

The cytochrome p450 (CYP) superfamily is responsible for the oxidation, peroxidation, and (or) reduction of vitamins, steroids, xenobiotics, and the majority of cardiovascular drugs in an oxygen- and NADPH-dependent manner. Although hepatic CYP have been studied extensively, the role of CYP in cardiovascular physiology and disease is poorly understood. Increasing evidence suggests that these enzymes play an important role in the pathogenesis of a number of cardiovascular diseases. The current review summarizes the understanding as to the role that dysregulated CYP expression and (or) activity may play in the onset and progression of cardiovascular disease.Key words: Cytochrome p450, heart, endothelial cell, ischemia, atherosclerosis, reactive oxygen species.
Effect of leptin administration versus re-feeding on hypothalamic neuropeptide gene expression in fasted male rats
Authors: McAlister Edward D , Van Vugt Dean A
Published: February 2005

Adipocytes are the primary source of circulating leptin. Leptin inhibits eating, increases metabolism, and stimulates the reproductive axis. Numerous hypothalamic neuropeptides have been implicated in leptin's behavioral and neuroendocrine effects, including neuropeptide Y (NPY) and cocaine- and amphetamine-regulated transcript (CART). The aim of this study was to investigate the physiological relevance of leptin's signaling of nutritional status by comparing the effects of leptin with the effects of re-feeding on fasting-induced changes in the expression of the long form of the leptin receptor (Ob-Rb), NPY, and CART. Adult male rats were fasted for 48 h and treated with either intra cere broventricular (i.c.v.) or subcutaneous (s.c.) leptin throughout the fast, or fed ad libitum for 24 h after terminating the fast. Expression of NPY, Ob-Rb, and CART mRNA in the arcuate nucleus (ARC) was determined by in situ hybridization histochemistry and compared with vehicle-treated fed or fasted controls. Fasting increased NPY and Ob-Rb expression and decreased CART expression in the ARC. Leptin (regardless of route) and re-feeding were equally effective in normalizing CART mRNA expression. A similar trend was observed with Ob-Rb expression. In contrast, neither re-feeding nor s.c. leptin reversed the increased expression of NPY that was induced by fasting. Only i.c.v. leptin was effective in this regard. Our results indicate leptin and re-feeding are equally effective in normalizing fasting-induced changes in CART and Ob-Rb expression, but less effective in normalizing NPY expression. These results suggest that leptin is the primary nutritional signal regulating CART and Ob-Rb expression in the ARC, and highlight potential differences between CART and NPY neuron sensitivity to leptin signaling.Key words: CART, leptin receptor, NPY, neuropeptide gene expression, fasting, refeeding, hypothalamus.
Na+ overload-induced mitochondrial damage in the ischemic heart
Authors: Takeo Satoshi , Tanonaka Kouichi
Published: February 2005

Ischemia induces a decrease in myocardial contractility that may lead more or less to contractile dysfunction in the heart. When the duration of ischemia is relatively short, myocardial contractility is immediately reversed to control levels upon reperfusion. In contrast, reperfusion induces myocardial cell death when the heart is exposed to a prolonged period of ischemia. This phenomenon is the so-called "reperfusion injury". Numerous investigators have reported the mechanisms underlying myocardial reperfusion injury such as generation of free radicals, disturbance in the intracellular ion homeostasis, and lack of energy for contraction. Despite a variety of investigations concerning the mechanisms for ischemia and ischemia–reperfusion injury, ionic disturbances have been proposed to play an important role in the genesis of the ischemia–reperfusion injury. In this present study, we focused on the contribution of Na+ overload and mitochondrial dysfunction during ischemia to the genesis of this ischemia–reperfusion injury.Key words: mitochondria, myocardial ischemia, Na+ channels, Na+/H+ exchanger, Na+ overload.