bluuebunny/crossref_metadata_2025 huggingface dataset:
Exhaled nitric oxide, systemic inflammation, and the spirometric response to inhaled fluticasone propionate in severe chronic obstructive pulmonary disease: A prospective study
Authors: Kunisaki Ken M. , Rice Kathryn L. , Janoff Edward N. , Rector Thomas S. , Niewoehner Dennis E.
Published: March 2008

Background: A subset of patients with chronic obstructive pulmonary disease (COPD) may respond more favorably to inhaled corticosteroids (ICS), but no simple method is currently utilized to predict the presence or absence of ICS responses in patients with COPD.

We evaluated the ability of exhaled nitric oxide (FENO) and serum inflammatory markers (C-reactive protein [CRP], interleukin-6 [IL-6], and interleukin-8 [IL-8]) to independently predict spirometric responses to ICS in patients with COPD.

Methods: Among 60 ex-smokers with severe COPD (mean FEV1 1.07 L, 36% of predicted), we conducted a single-arm, open-label study. Participants spent four weeks free of any ICS, followed by four weeks of ICS use (fluticasone propionate 500 mcg twice daily). FENO, CRP, IL-6, IL-8, and pre-bronchodilator spirometry were measured immediately before and after the four weeks of ICS use.

Results: Baseline FENO, CRP, IL-6, and IL-8 showed no correlations to FEV1 responses to ICS. ICS responders (increase in FEV1 ≥ 200 mL after four weeks of ICS) did have significantly higher baseline FENO levels compared with non-responders (46.5 parts per billion [ppb] vs. 25 ppb, p = 0 .028). The receiver operating characteristic curve for FENO to discriminate responders from non-responders had an area under curve of 0.72. Baseline serum inflammatory markers did not differ between responders and non-responders.

Conclusion: In ex-smokers with severe COPD, a measure of local pulmonary inflammation, FENO, may be more closely associated with FEV1 responses to four weeks of ICS than are standard markers of systemic inflammation, serum CRP, IL-6, and IL-8
Review: Treating patients with respiratory disease who smoke
Authors: Braganza Georgina , Chaudhuri Rekha , Thomson Neil C.
Published: March 2008

The high prevalence of cigarette smoking in patients with respiratory disease puts them at risk of developing clinically important drug interactions. Cigarette smoking reduces the therapeutic response to certain drugs such as theophyllines through the induction of hepatic cytochrome P450 isoenzymes. Smokers with asthma and patients with COPD have reduced sensitivity to corticosteroids, possibly due to non-eosinophilic airway inflammation, altered glucocorticoid receptor activity or reduced histone deacetylase activity. Although all smokers should be encouraged to stop smoking, there is limited information on the influence of smoking cessation on the therapeutic and anti-inflammatory effects of a number of the drugs used in the treatment of respiratory disease.
Review: Endothelial dysfunction: A potential tool in gender related cardiovascular disease
Authors: Patel Pawan D. , Arora Rohit R.
Published: March 2008

The overwhelming importance of distinctive cardiovascular disease profile in women has stimulated enormous efforts to disclose its cause. In this review, we discuss vascular endothelium as a potential phenotypic marker for the genetic difference. As it is a potentially modifiable factor for cardiovascular disease, every effort should be made to detect it, either directly or indirectly, at the earliest in females who are at risk, so that the future cardiovascular events might be prevented.
Original Research: Capillary rarefaction in treated and untreated hypertensive subjects
Authors: Cheng Cynthia , Daskalakis Constantine , Falkner Bonita
Published: March 2008

This study aimed to determine if capillary rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural capillary rarefaction measures were not different between the three groups. Functional capillary rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation.
Review: Percutaneous coronary interventions and statins therapy
Authors: Nusca Annunziata , Melfi Rosetta , Di Sciascio Germano
Published: March 2008

Statins exert a number of beneficial effects on endothelial function and atherosclerotic plaque, modulating oxidative stress and inflammation, with subsequent, well documented, primary and secondary prevention of coronary artery disease. Periprocedural myocardial infarction and contrast induced nephropathy, after percutaneous coronary intervention (PCI), are associated with a worse outcome on long term follow-up. In the ARMYDA study, pretreatment with statins before elective PCI reduces periprocedural myocardial infarction in patients with stable angina. Moreover, the ARMYDA ACS was the first randomized, prospective trial that demonstrated that an acute loading with a high dose of atorvastatin prevents myocardial damage in patients with unstable syndromes undergoing early ( <48 hours) coronary angiography and consequent angioplasty. Statins could also have beneficial effects by reducing expression of adhesion molecules in endothelial cells (ICAM-1 and E-Selectin) as demonstrated in the ARMYDA-CAMS study. Furthermore, patients receiving statins at the time of procedure show a significantly reduced incidence of contrast-induced nephropathy. All this evidence may strongly influence the clinical practice of an interventional cardiologist.
Heat Seal Strength of Barrier Films Used in Vacuum Insulation Panels At Room Temperature and At -130°C
Authors: van Malsen J. , Tenpierik M.J. , Looman R.H.J. , Cauberg J.J.M.
Published: March 2008

This paper describes experiments conducted in the framework of a research project aimed at finding suitable barrier films for vacuum insulation panels (VIPs), which are used for applications in the cooling industry (especially for ducts in liquified natural gas [LNG] installations) and in the building industry. It explores the heat seal strength of four makes of film used for this purpose. A secondary purpose was to investigate the influence of the heat seal parameters on the heat seal strength of the tested films. The heat seals were tested at room temperature and at -130°C, from which it readily became clear that the heat seal parameters can be chosen freely within certain limits.
Iron depletion limits intracellular bacterial growth in macrophages
Authors: Paradkar Prasad N. , De Domenico Ivana , Durchfort Nina , Zohn Irene , Kaplan Jerry , Ward Diane McVey
Published: March 2008

Many intracellular pathogens infect macrophages and these pathogens require iron for growth. Here we demonstrate in vitro that the intracellular growth of Chlamydia psittaci, trachomatis, and Legionella pneumophila is regulated by the levels of intracellular iron. Macrophages that express cell surface ferroportin, the only known cellular iron exporter, limit the intracellular growth of these bacteria. Hepcidin is an antimicrobial peptide secreted by the liver in response to inflammation. Hepcidin binds to ferroportin mediating its internalization and degradation. Addition of hepcidin to infected macrophages enhanced the intracellular growth of these pathogens. Macrophages from flatiron mice, a strain heterozygous for a loss-of-function ferroportin mutation, showed enhanced intracellular bacterial growth independent of the presence of exogenous hepcidin. Macrophages, from wild-type or flatiron mice, incubated with the oral iron chelator deferriprone or desferasirox showed reduced intracellular bacterial growth suggesting that these chelators might be therapeutic in chronic intracellular bacterial infections.
Development of patatin knockdown potato tubers using RNA interference (RNAi) technology, for the production of human-therapeutic glycoproteins
Authors: Kim Yoon-Sik , Lee Yong-Hwa , Kim Hyun-Soon , Kim Mi-Sun , Hahn Kyu-Woong , Ko Jeong-Heon , Joung Hyouk , Jeon Jae-Heung
Published: April 2008

Background

Patatins encoded by a multi-gene family are one of the major storage glycoproteins in potato tubers. Potato tubers have recently emerged as bioreactors for the production of human therapeutic glycoproteins (vaccines). Increasing the yield of recombinant proteins, targeting the produced proteins to specific cellular compartments, and diminishing expensive protein purification steps are important research goals in plant biotechnology. In the present study, potato patatins were eliminated almost completely via RNA interference (RNAi) technology to develop potato tubers as a more efficient protein expression system. The gene silencing effect of patatins in the transgenic potato plants was examined at individual isoform levels.

Results

Based upon the sequence similarity within the multi-gene family of patatins, a highly conserved target sequence (635 nts) of patatin gene pat3-k1 [GenBank accession no. DQ114421] in potato plants (Solanum tuberosum L.) was amplified for the construction of a patatin-specific hairpin RNAi (hpRNAi) vector. The CaMV 35S promoter-driven patatin hpRNAi vector was transformed into the potato cultivar Desiree by Agrobacterium-mediated transformation. Ten transgenic potato lines bearing patatin hpRNA were generated. The effects of RNA interference were characterized at both the protein and mRNA levels using 1D and 2D SDS/PAGE and quantitative real-time RT-PCR analysis. Dependent upon the patatin hpRNAi line, patatins decreased by approximately 99% at both the protein and mRNA levels. However, the phenotype (e.g. the number and size of potato tuber, average tuber weight, growth pattern, etc.) of hpRNAi lines was not distinguishable from wild-type potato plants under both in vitro and ex vitro growth conditions. During glycoprotein purification, patatin-knockdown potato tubers allowed rapid purification of other potato glycoproteins with less contamination of patatins.

Conclusion

Patatin-specific hpRNAi effectively suppressed the expression of a majority of patatin variants in potato tubers via the specific degradation of individual mRNAs of the patatin multi-gene family. More importantly, patatin-knockdown potato tubers appear to be an ideal host for the production of human therapeutic glycoproteins, because they eventually allow fast, easy purification of recombinant proteins, with less contamination from potato glycoprotein patatins.
Killing cancer cells by targeted drug-carrying phage nanomedicines
Authors: Bar Hagit , Yacoby Iftach , Benhar Itai
Published: April 2008

Background

Systemic administration of chemotherapeutic agents, in addition to its anti-tumor benefits, results in indiscriminate drug distribution and severe toxicity. This shortcoming may be overcome by targeted drug-carrying platforms that ferry the drug to the tumor site while limiting exposure to non-target tissues and organs.

Results

We present a new form of targeted anti-cancer therapy in the form of targeted drug-carrying phage nanoparticles. Our approach is based on genetically-modified and chemically manipulated filamentous bacteriophages. The genetic manipulation endows the phages with the ability to display a host-specificity-conferring ligand. The phages are loaded with a large payload of a cytotoxic drug by chemical conjugation. In the presented examples we used anti ErbB2 and anti ERGR antibodies as targeting moieties, the drug hygromycin conjugated to the phages by a covalent amide bond, or the drug doxorubicin conjugated to genetically-engineered cathepsin-B sites on the phage coat. We show that targeting of phage nanomedicines via specific antibodies to receptors on cancer cell membranes results in endocytosis, intracellular degradation, and drug release, resulting in growth inhibition of the target cells in vitro with a potentiation factor of >1000 over the corresponding free drugs.

Conclusion

The results of the proof-of concept study presented here reveal important features regarding the potential of filamentous phages to serve as drug-delivery platform, on the affect of drug solubility or hydrophobicity on the target specificity of the platform and on the effect of drug release mechanism on the potency of the platform. These results define targeted drug-carrying filamentous phage nanoparticles as a unique type of antibody-drug conjugates.
Inhibition of corneal inflammation by liposomal delivery of short-chain, C-6 ceramide
Authors: Sun Yan , Fox Todd , Adhikary Gautam , Kester Mark , Pearlman Eric
Published: March 2008

Ceramide is recognized as an antiproliferative and proapoptotic sphingolipid metabolite; however, the role of ceramide in inflammation is not well understood. To determine the role of C6-ceramide in regulating inflammatory responses, human corneal epithelial cells were treated with C6-ceramide in 80 nm diameter nanoliposome bilayer formulation (Lip-C6) prior to stimulation with UV-killed Staphylococcus aureus. Lip-C6 (5 μM) inhibited the phosphorylation of proinflammatory and proapoptotic MAP kinases JNK and p38 and production of neutrophil chemotactic cytokines CXCL1, CXCL5, and CXCL8. Lip-C6 also blocked CXC chemokine production by human and murine neutrophils. To determine the effect of Lip-C6 in vivo, a murine model of corneal inflammation was used in which LPS or S. aureus added to the abraded corneal surface induces neutrophil infiltration to the corneal stroma, resulting in increased corneal haze. Mice were treated topically with 2 nMoles (811 ng) Lip-C6 or with control liposomes prior to, or following, LPS or S. aureus stimulation. We found that corneal inflammation was significantly inhibited by Lip-C6 but not control liposomes given prior to, or following, activation by LPS or S. aureus. Furthermore, Lip-C6 did not induce apoptosis of corneal epithelial cells in vitro or in vivo, nor did it inhibit corneal wound healing. Together, these findings demonstrate a novel, anti-inflammatory, nontoxic, therapeutic role for liposomally delivered short-chain ceramide.
Prologue
Authors: Noble Denis
Published: March 2008

The new vogue for systems biology is an important development. It is time to complement reductionist molecular biology by integrative approaches. But this welcome development is in danger of losing its way. Many of the early implementations of the approach are very low level, in some cases hardly more than an extension of genomics and bioinformatics. In this paper, I outline some general principles that could form the basis of systems biology as a truly multilevel approach. We need the insights obtained from a higher level analysis in order to succeed at the lower levels. Higher levels in biological systems impose boundary conditions on the lower levels. Without understanding those conditions and their effects, we will be seriously restricted in understanding the logic of living systems. Sydney Brenner has insisted that “the cell is the correct level of abstraction.” I would go further and insist on the value of abstraction at even higher levels than the cell, while recognizing the cell as a landmark level of biological organization. The principles outlined are illustrated with examples from cardiac and other aspects of physiology and biochemistry.
The Death of Transcriptional Chauvinism in the Control and Regulation of Cardiac Contractility
Authors: Sadayappan Sakthivel , Robbins Jeffrey
Published: March 2008

In the last 25 years we have witnessed the triumph of the genome. There are now well over 200 complete genome sequences. The application of modern solid state technologies to genomic sequencing promises affordable personalized sequences for the individual in the very near future. With this explosion in DNA sequence data, the focus in the immediate past has been on the primary DNA sequence, the cis‐trans interactions that underlie controlled transcription, cataloging the transcriptome, and applying rudimentary systems analysis to those data sets in an attempt to assign molecular signatures to normal and abnormal physiological states. However, it is becoming clear that the post‐transcriptional processes, which operate at the levels of RNA stability and selection for translational initiation, as well as the post‐translational processes of protein stability, trafficking, and secondary modifications, such as phosphorylation, all play key roles in the homeostasis of the contractile apparatus and its overall function. Defining the interplay of these processes, in concert with the signaling pathways that allow transcription, translation, and post‐translational processes to be quickly modified in response to events outside of the cardiomyocyte are leading to an understanding of the spatial and temporal requirements for each of these processes in controlling cardiac output. In order to confirm the importance of post‐translational modification in controlling cardiac contractility in vivo, we examined the role that post‐translational modification of an important component of the cardiac contractile apparatus, myosin binding protein C (MyBP‐C), plays in the normal and diseased heart by creating transgenic mice in which the effects of chronic cardiac MyBP‐C phosphorylation and dephosphorylation could be determined.
MicroRNAs Control Gene Expression
Authors: Catalucci Daniele , Latronico Michael V. G. , Condorelli Gianluigi
Published: March 2008

Growing evidence indicates that microRNAs (miRNAs) are involved in a variety of basic biological processes, including cell proliferation, apoptosis, stress response, hematopoesis, and oncogenesis. In fact, bioinformatic analysis predicts that each miRNA may regulate hundreds of targets, suggesting that miRNAs may play roles in almost every biological pathway. Information from recent studies indicate that miRNAs are involved in the regulation of cardiac development and pathophysiology. Notably, knockout of miRNA‐1 was associated with cardiac defects, including regulation of cardiac morphogenesis, electrical conduction, and cell cycle control. Our group has identified a critical role of miRNA‐1 and miRNA‐133 in determining cardiac hypertrophy and has shown an inverse correlation of expression with cardiac hypertrophy, in vitro, in murine models and in human disease states associated with cardiac hypertrophy. Remarkably, in vivo experiments with a single infusion of antagomir‐133 oligonucleotide, a small cholesterol‐conjugated RNA sequence suppressing endogenous miRNA, induced marked and sustained cardiac hypertrophy. Shedding light on the role of this new class of RNA molecules in heart physiology and pathology may reveal possible future therapeutic applications for the treatment of heart diseases.
Shear Fluid‐induced Ca2+ Release and the Role of Mitochondria in Rat Cardiac Myocytes
Authors: Belmonte Steve , Morad Martin
Published: March 2008

Cardiac myocyte contraction occurs when Ca2+ influx through voltage‐gated L‐type Ca2+ channels causes Ca2+ release from ryanodine receptors of the sarcoplasmic reticulum (SR). Although mitochondria occupy about 35% of the cell volume in rat cardiac myocytes, and are thought to be located <300 nm from the junctional SR, their role in the beat‐to‐beat regulation of cardiac Ca2+ signaling remains unclear. We have recently shown that rapid (∼20 ms) application of shear fluid forces (∼25 dynes/cm2) to rat cardiac myocytes triggers slowly (∼300 ms) developing Cai transients that were independent of activation of all transmembrane Ca2+ transporting pathways, but were suppressed by FCCP, CCCP, and Ru360, all of which are known to disrupt mitochondrial function. We have here used rapid 2‐D confocal microscopy to monitor fluctuations in mitochondrial Ca2+ levels ([Ca2+]m) and mitochondrial membrane potential (ΔΨm) in rat cardiac myocytes loaded either with rhod‐2 AM or tetramethylrhodamine methyl ester (TMRM), respectively. Freshly isolated intact rat cardiac myocytes were plated on glass coverslips and incubated in 5 mM Ca2+ containing Tyrode's solution and 40 mM 2,3‐butanedione monoxime (BDM) to inhibit cell contraction. Alternatively, myocytes were permeabilized with 10 μM digitonin and perfused with an “intracellular” solution containing 10 μM free [Ca2+], 5 mM EGTA, and 15 mM BDM. Direct [Ca2+]m measurements showed transient mitochondrial Ca2+ accumulation after exposure to 10 mM caffeine, as revealed by a 66% increase in the rhod‐2 fluorescence intensity. Shear fluid forces, however, produced a 12% decrease in signal, suggesting that application of a mechanical force releases Ca2+ from the mitochondria. In addition, caffeine and CCCP or FCCP strongly reduced ΔΨm, while application of a pressurized solution produced a transient ΔΨm hyperpolarization in intact ventricular myocytes loaded with TMRM. The close proximity of mitochondria to ryanodine receptors and large [Ca2+] that develop in microdomains following calcium release are likely to play a critical role in regulating cytosolic Ca2+ signaling. We suggest that mitochondria may accumulate and release Ca2+ in response to mechanical forces generated by blood flow, independent of surface membrane–regulated CICR. The extent to which such a signaling mechanism contributes to stretch‐induced increase in myocardial force and pathogenesis of arrhythmias remains to be assessed.
The Role of Ca2+ in Coupling Cardiac Metabolism with Regulation of Contraction
Authors: Yaniv Yael , Stanley William C. , Saidel Gerald M. , Cabrera Marco E. , Landesberg Amir
Published: March 2008

The heart adapts the rate of mitochondrial ATP production to energy demand without noticeable changes in the concentration of ATP, ADP and Pi, even for large transitions between different workloads. We suggest that the changes in demand modulate the cytosolic Ca2+ concentration that changes mitochondrial Ca2+ to regulate ATP production. Thus, the rate of ATP production by the mitochondria is coupled to the rate of ATP consumption by the sarcomere cross‐bridges (XBs). An integrated model was developed to couple cardiac metabolism and mitochondrial ATP production with the regulation of Ca2+ transient and ATP consumption by the sarcomere. The model includes two interrelated systems that run simultaneously utilizing two different integration steps: (1) The faster system describes the control of excitation contraction coupling with fast cytosolic Ca2+ transients, twitch mechanical contractions, and associated fluctuations in the mitochondrial Ca2+. (2) A slower system simulates the metabolic system, which consists of three different compartments: blood, cytosol, and mitochondria. The basic elements of the model are dynamic mass balances in the different compartments. Cytosolic Ca2+ handling is determined by four organelles: sarcolemmal Ca2+ influx and efflux; sarcoplasmic reticulum (SR) Ca2+ release and sequestration (SR); binding and dissociation from sarcomeric regulatory troponin complexes; and mitochondrial Ca2+ flows. Mitochondrial Ca2+ flows are determined by the Ca2+ uniporter and the mitochondrial Na+Ca2+ exchanger. The cytosolic Ca2+ determines the rate of ATP consumption by the sarcomere. Ca2+ binding to troponin regulates the rate of XBs recruitment and force development. The mitochondrial Ca2+ concentration determines the pyruvate dehydrogenase activity and the rate of ATP production by the F1‐F0 ATPase. The workload modulates the cytosolic Ca2+ concentration through feedback loops. The preload and afterload affect the number of strong XBs. The number of strong XBs determines the affinity of troponin for Ca2+, which alters the cytosolic Ca2+ transient. Model simulations quantify the role of Ca2+ in simultaneously controlling the power of contraction and the rate of ATP production. It explains the established empirical observation that significant changes in the metabolic fluxes can occur without significant changes in the key nucleotide (ATP and ADP) concentrations. Quantitative investigations of the mechanisms underlying the cardiac control of biochemical to mechanical energy conversion may lead to novel therapeutic modalities for the ischemic and failing myocardium.
Intracellular Transport
Authors: Roux Aurélien , Cuvelier Damien , Bassereau Patricia , Goud Bruno
Published: March 2008

Considerable effort over the past three decades has allowed the identification of the protein families that control the cellular machinery responsible for intracellular transport within eukaryotic cells. These proteins are estimated to represent about 10–20% of the human “proteome.” The complexity of intracellular transport makes useful the development of model membranes. We describe here experimental systems based on lipid giant unilamellar vesicles (GUVs), which are attached to kinesin molecules. These systems give rise to thin membrane tubes and to complex tubular networks when incubated in vitro with microtubules and ATP. This type of assay, which mimics key events occurring during intracellular transport, allows physicists and biologists to understand how the unique mechanical properties of lipid membranes could be involved in the budding process, the sorting of cargo proteins and lipids, and the separation of the buds from a donor membrane.
Linking Cellular Energetics to Local Flow Regulation in the Heart
Authors: Bassingthwaighte James B.
Published: March 2008

A mathematical model has been developed to explain the metabolic and energetic responses induced by abnormal routes of cardiac excitation. For example, in left bundle branch block (LBBB), both glucose uptake and flow are reduced in the septal region, similar to the situation in dogs paced at the right ventricular outflow tract. In these conditions the septum is activated early, the sarcomere lengths shorten rapidly against low left ventricular (LV) pressure, and the blood flow to the interventricular septum diminishes. In contrast, the work load and the blood flow increases in the later‐activated LV free wall. To provide a logical, quantitatively appropriate representation, the model links: (1) the processes of excitation–contraction coupling; (2) regional ATP utilization for force development at the cross‐bridge, for ion pumping, and for cell maintenance; (3) the regulation of demands on local fatty acid and glucose metabolism for ATP generation by glycolysis and oxidative phosphorylation; and (4) feedback regulation of blood flow to supply substrate and oxygen. The heart is considered as a cylinder composed of two parts: an early‐activated region and a late‐activated region in tandem, but activated separately with the time delay representing the time for excitation to spread from septum to free wall. The same model equations and parameter sets are used for the two regions. The contraction of the early‐activated region stretches the other region, with the result that the early‐stimulated region has diminished oxygen requirements compared to those found with simultaneous stimulation. The late‐activated region has increased work and increased oxygen consumption, as seen in the intact heart. Integrating the modeling of cardiac energy metabolism with local blood flow regulation and capillary–tissue substrate exchange provides a quantitative description, an hypothesis formulated to stimulate further experimentation to test its validity. The hypothesis “explains” observations of contraction and metabolism in LBBB, but whether this concept can be extended to explain the normal flow heterogeneity in the heart remains unknown.
Controlling Cardiac Transport and Plaque Formation
Authors: Aronis Ze'ev , Raz Sagi , Martinez Elisha J.P. , Einav Shmuel
Published: March 2008

Macro‐particles transported in the bloodstream, such as LDL particles and macrophages, are considered to be one of the initiating factors of atherosclerotic plaque development. LDL infiltration from the bloodstream into a blood vessel's wall, whether the coronary, peripheral, or carotid arteries, is considered a major inflammatory factor, recruiting macrophages from the blood flow and leading to the formation of vulnerable atherosclerotic plaques. Infiltration sites are influenced by patterns of blood flow, as regions of lower shear stresses and high oscillations may give rise to higher infiltration rates through the endothelium, exacerbating the growth of a plaque and its tendency to rupture. Previous studies demonstrated a high prevalence of rupture sites proximal to the minimum lumen area, which raised the question of whether the existence of two distinct adjacent plaques, in which the distal plaque is more severe, can give rise to hemodynamic forces that can push the non‐stenotic plaque to rupture. Models of the coronary arteries with one and two eccentric and concentric stenotic narrowings were built into a closed flow loop. The single stenosis model had a 75% area reduction narrowing (representing the vunerable atherosclerotic plaque) with relevant elastic properties. The double stenosis model included an additional distal 84% area reduction narrowing. The flow in the area between the two stenoses was recorded and analyzed using continuous doppler particle image velocimetry (CDPIV), together with the hydrostatic pressure acting on the proximal plaque. Results indicated that the combined shear rates and pressure effects in a model with a significant distal stenosis can contribute to the increase in plaque instability by LDL and enhanced macrophage uptake. The highly oscillatory nature of the disturbed flow near the shoulder of the vulnerable atherosclerotic plaque enriches its lipid soft core, and the high hydrostatic pressures acting on the same lesion in this geometry induce high internal maximal stresses that can trigger the rupture of the plaque.
Multiscale and Modular Analysis of Cardiac Energy Metabolism
Authors: Van Beek Johannes H.G.M.
Published: March 2008

Computational models of large molecular systems can be assembled from modules representing biological function emerging from interactions among a small subset of molecules. Experimental information on isolated molecules can be integrated with the response of the network as a whole to estimate crucial missing parameters. As an example, a “skeleton” model is analyzed for the module regulating dynamic adaptation of myocardial oxidative phosphorylation (OxPhos) to fluctuating cardiac energy demand. The module contains adenine nucleotides, creatine, and phosphate groups. Enzyme kinetic equations for two creatine kinase (CK) isoforms were combined with the response time of OxPhos (tmito; generalized time constant) to steps in the cardiac pacing rate to identify all module parameters. To obtain tmito, the time course of O2uptake was measured for the whole heart. An O2transport model was used to deconvolute the whole‐heart response to the mitochondrial level. By optimizing mitochondrial outer membrane permeability to 21 μm/s the experimental tmito = 3.7 s was reproduced. Thisin vivovalue is about four times larger, or smaller, respectively, than conflicting values obtained from two differentin vitrostudies. This demonstrates an important rule for multiscale analysis: experimental responses and modeling of the system at the larger scale allow one to estimate essential parameters for the interfaces of components which may have been altered during physical isolation. The model correctly predicts a smaller tmitowhen CK activity is reduced. The model further predicts a slower response if the muscle CK isoform is overexpressed and a faster response if mitochondrial CK is overexpressed. The CK system is very effective in decreasing maximum levels of ADP during systole and reducing average Pilevels over the whole cardiac cycle.
Discovering Regulators of theDrosophilaCardiac Hypoxia Response Using Automated Phenotyping Technology
Authors: Feala Jacob D. , Omens Jeffrey H. , Paternostro Giovanni , McCulloch Andrew D.
Published: March 2008

Necrosis and apoptosis during acute myocardial infarction result in part from the inability of hypoxic cardiac myocytes to match ATP supply and demand. In contrast, hypoxia‐tolerant organisms, such asDrosophila, can rapidly regulate cellular metabolism to survive large oxygen fluctuations. A genetic screen of fly heart function during acute hypoxia can be an unbiased way to discover essential enzymes and novel signaling proteins involved in this response. We have developed a prototype to show proof of concept for a genome‐scale screen, using computer automation to rapidly gatherin vivohypoxic heart data in adultDrosophila. Our system automatically anesthetizes flies, deposits them on a microscope slide, and locates the heart organ of each fly. The system then applies a hypoxia stimulus, acquires time‐space (M‐mode) images of the heart walls, and analyzes heart rate and rhythm. The prototype can produce highly controlled measurements of up to 55 flies per hour, which we demonstrated by characterizing the effect of temperature, oxygen content, and genetic background on the hypoxia response. We discuss the possible applications of a genome‐wide cardiac phenotype data set in systems biology analyses of hypoxic metabolism, using genome‐scale interaction networks and constraint‐based metabolic models.
Control of Cardiac Rate by “Funny” Channels in Health and Disease
Authors: Barbuti Andrea , DiFrancesco Dario
Published: March 2008

Activation of the “funny” (pacemaker, If) current during the diastolic depolarization phase of an action potential is the main mechanism underlying spontaneous, rhythmic activity of cardiac pacemaker cells. In the past three decades, a wealth of evidence elucidating the function of the funny current in the generation and modulation of cardiac pacemaker activity has been gathered. The slope of early diastolic depolarization, and thus the heart rate, is controlled precisely by the degree of If activation during diastole. If is also accurately and rapidly modulated by changes of the cytosolic concentration of the second messenger cAMP, operated by the autonomous nervous system through β‐adrenergic, mainly β2, and in the opposite way by muscarinic receptor, stimulation. Recently, novel in vivo data, both in animal models and humans, have been collected that confirm the key role of If in pacemaking. In particular, an inheritable point mutation in the cyclic nucleotide‐binding domain of human HCN4, the main hyperpolarization‐activated cyclic nucleotide (HCN) isoform contributing to native funny channels of the sinoatrial node, was shown to be associated with sinus bradycardia in a large family. Because of their properties, funny channels have long been a major target of classical pharmacological research and are now target of innovative gene/cell‐based therapeutic approaches aimed to exploit their function in cardiac rate control.
Controlling Ischemic Cardiovascular Disease
Authors: Beyar Rafael
Published: March 2008

Progress in cardiovascular disease understanding and management continues at an exponential pace. Our understanding of the molecular basis of disease is enhanced by newer molecular measurement techniques, sophisticated models of physiological protein functions, understanding of the genetic foundation for diseases, and the incorporation of population genetic tools in our clinical analysis. In this review, I discuss prevention and therapy of coronary stenosis impeding coronary flows, prevention of acute and chronic manifestation of coronary flow impairment, and interfering with myocardial manifestation of acute or chronic deprivation of coronary flow. Mechanical heart failure and arrhythmias are common causes of myocardial dysfunction that originate, in part, from the loss of myocardial tissue and function. Techniques for interfering with cardiac function, in order to address the molecular mechanisms associated with restenosis, range from pharmacologic to mechanical procedures including mechanical dilation and scaffolding of coronary stenosis. The use of stents with and without drug coating is leading the clinical world of revascularization side‐by‐side with cardiac bypass surgery. Other topics that are discussed here include managing myocardial damage and acute and chronic pump failure. Finally, population genetics of cardiac health and the potential for genetic therapeutic guidance in managing ischemic cardiovascular diseases are discussed.
Elevation in Intracellular Long-Chain Acyl-Coenzyme A Esters Lead to Reduced β-Cell Excitability via Activation of Adenosine 5′-Triphosphate-Sensitive Potassium Channels
Authors: Webster Nicola J. , Searle Gavin J. , Lam Patrick P. L. , Huang Ya-Chi , Riedel Michael J. , Harb George , Gaisano Herbert Y. , Holt Andrew , Light Peter E.
Published: March 2008

Closure of pancreatic β-cell ATP-sensitive potassium (KATP) channels links glucose metabolism to electrical activity and insulin secretion. It is now known that saturated, but not polyunsaturated, long-chain acyl-coenyzme A esters (acyl-CoAs) can potently activate KATP channels when superfused directly across excised membrane patches, suggesting a plausible mechanism to account for reduced β-cell excitability and insulin secretion observed in obesity and type 2 diabetes. However, reduced β-cell excitability due to elevation of endogenous saturated acyl-CoAs has not been confirmed in intact pancreatic β-cells. To test this notion directly, endogenous acyl-CoA levels were elevated within primary mouse β-cells using virally delivered overexpression of long-chain acyl-CoA synthetase-1 (AdACSL-1), and the effects on β-cell KATP channel activity and cell excitability was assessed using the perforated whole-cell and cell-attached patch-clamp technique. Data indicated a significant increase in KATP channel activity in AdACSL-1-infected β-cells cultured in medium supplemented with palmitate/oleate but not with the polyunsaturated fat linoleate. No changes in the ATP/ADP ratio were observed in any of the groups. Furthermore, AdACSL-1-infected β-cells (with palmitate/oleate) showed a significant decrease in electrical responsiveness to glucose and tolbutamide and a hyperpolarized resting membrane potential at 5 mm glucose. These results suggest a direct link between intracellular fatty ester accumulation and KATP channel activation, which may contribute to β-cell dysfunction in type 2 diabetes.
Hypothalamic Neuropeptide Expression of Juvenile and Middle-Aged Rats after Early Postnatal Food Restriction
Authors: Remmers Floor , Verhagen Linda A. W. , Adan Roger A. H. , Delemarre-van de Waal Henriette A.
Published: March 2008

Rats subjected to early postnatal food restriction (FR) show persistent changes in energy balance. The hypothalamus plays a major role in the regulation of energy balance. Therefore, we hypothesized that early postnatal food restriction induces developmental programming of hypothalamic gene expression of neuropeptides involved in this regulation. In the hypothalamus of juvenile and middle-aged rats that were raised in control (10 pups) or FR litters (20 pups), gene expression was investigated for neuropeptide Y (NPY), agouti-related protein (AgRP), proopiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART) in the arcuate nucleus (ARC); CRH and TRH in the paraventricular nucleus; and melanin-concentrating hormone (MCH) and orexin in the lateral hypothalamic area. Early postnatal FR acutely and persistently reduced body size. Juvenile FR rats had significantly reduced CART gene expression and increased MCH expression. In middle-aged FR rats, POMC and CART mRNA levels were significantly reduced. The ratio between expression of the ARC orexigenic peptides (NPY and AgRP) and anorexigenic peptides (POMC and CART) was increased in juvenile, but not in middle-aged, FR rats. These results suggest that in neonatal rats, FR already triggers the ARC, and to a lesser extent the lateral hypothalamic area, but not the paraventricular nucleus, to increase expression of orexigenic relative to anorexigenic peptides. In addition, with enduring small body size and normalized hypothalamic gene expression, the adult FR rats appeared to have accepted this smaller body size as normal. This suggests that the body weight set-point was differently programmed in animals with early postnatal FR.
Gonadotropin-Releasing Hormone-1 Neuronal Activity Is Independent of Hyperpolarization-Activated Cyclic Nucleotide-Modulated Channels but Is Sensitive to Protein Kinase A-Dependent Phosphorylation
Authors: Constantin Stephanie , Wray Susan
Published: March 2008

Pulsatile release of GnRH-1 stimulates the anterior pituitary and induces secretion of gonadotropin hormones. GnRH-1 release is modulated by many neurotransmitters that act via G protein-coupled membrane receptors. cAMP is the most ubiquitous effector for these receptors. GnRH-1 neurons express hyperpolarization-activated cyclic nucleotide-modulated (HCN) channel protein in vivo. HCN channels are involved in neuronal pacemaking and can integrate cAMP signals. cAMP-dependent protein kinase (PKA) is also activated by cAMP signals, and PKA-dependent phosphorylation modulates voltage-activated channels. In this report, these two pathways were examined in GnRH-1 neurons as integrators of forskolin (FSK)-induced stimulation. The HCN3 isoform was detected in GnRH-1 neurons obtained from mouse nasal explants. ZD7288, a HCN channel blocker, significantly reduced the efficiency of FSK to stimulate GnRH-1 neurons, whereas blockade of PKA with Rp-adenosine-3′,5′-cyclic monophosphorothioate triethylammonium did not attenuate the FSK-induced stimulation. To ensure that disruption of HCN channels on GnRH-1 neurons was responsible for reduction of FSK stimulation, experiments were performed removing γ-aminobutyric acid (GABA), the major excitatory input to GnRH-1 neurons in nasal explants. Under these conditions, Rp-adenosine-3′,5′-cyclic monophosphorothioate triethylammonium, but not ZD7288, altered the FSK-induced response of GnRH-1 neurons. These studies indicate that PKA-dependent phosphorylation is involved in the FSK-induced stimulation of GnRH-1 neurons rather than HCN channels, and HCN channels integrate the FSK-induced stimulation on GABAergic neurons. In addition, blockade of HCN channels did not modify basal GnRH-1 neuronal activity when GABAergic input was intact or removed, negating a role for these channels in basal GABAergic or GnRH-1 neuronal activity.
Efficacy of Ghrelin as a Therapeutic Approach for Age-Related Physiological Changes
Authors: Ariyasu Hiroyuki , Iwakura Hiroshi , Yamada Go , Nakao Kazuwa , Kangawa Kenji , Akamizu Takashi
Published: March 2008

Aging is associated with decreases in food intake and GH secretion, termed the anorexia of aging and somatopause, respectively. The mechanisms underlying these phenomena are not fully understood. Although many approaches have attempted to improve these age-related physiological changes, none have achieved satisfactory results. Ghrelin, a 28-amino-acid acylated peptide, was identified as an endogenous ligand for the GH secretagogue receptor. Ghrelin stimulates GH secretion and food intake in animals and humans. Previous studies have demonstrated that the mean plasma concentrations of ghrelin in normal-weight elderly people were lower than those in younger people. We hypothesized that ghrelin administration might improve the metabolic and physiological changes that accompany the anorexia of aging and somatopause. First, 75-wk-old mice fasted for 72 h, after which they resumed feeding with sc administration of ghrelin (360 μg/kg) twice daily for 4 d. Multiple administrations of ghrelin after a 72-h fast increased food intake and hastened body weight recovery with a high lean body mass ratio. Next, 50-wk-old mice were sc injected with rat ghrelin (40 μg/kg) twice weekly from 50–80 wk of age. Long-term administration of ghrelin kept aged mice with low body weight and low adiposity. These results suggest that ghrelin might be a novel approach for the therapy of age-related metabolic and physiological changes.
Dynamic regulation of ubiquitylation and deubiquitylation at the central spindle during cytokinesis
Authors: Mukai Akiko , Mizuno Emi , Kobayashi Kaoru , Matsumoto Masaki , Nakayama Keiichi I. , Kitamura Naomi , Komada Masayuki
Published: April 2008

During cytokinesis, the central spindle, a bundle of interdigitated anti-parallel microtubules between separating chromosomes, recruits various cytokinetic regulator proteins to the cleavage region. Here, we show that the level of protein ubiquitylation is strikingly and transiently elevated in Aurora B kinase-positive double-band regions of the central spindle during cytokinesis. Two deubiquitylating enzymes UBPY and AMSH, which act on endosomes in interphase, were also recruited to the cleavage region. Whereas UBPY was detected only in the final stage of cytokinesis at the midbody, AMSH localized to a ring structure surrounding the mitotic kinesin MKLP1-positive region of the central spindle and midbody throughout cytokinesis. Depletion of cellular UBPY or AMSH led to defects in cytokinesis. VAMP8, a v-SNARE required for vesicle fusion in cytokinesis, localized to the central spindle region positive for ubiquitylated proteins, and underwent ubiquitylation and deubiquitylation by both UBPY and AMSH. Our results thus implicate the ubiquitylation/deubiquitylation of proteins including VAMP8 in cytokinesis.
A Review of János Kornai's By Force of Thought: Irregular Memoirs of an Intellectual Journey
Authors: Roland Gérard
Published: April 2008

This article reviews the memoirs of János Kornai. The famous Hungarian economist describes his life experiences and the concurrent history of Hungary. More importantly, he leads us through his intellectual evolution, explaining how his thinking evolved, how it was influenced by events, how one research question led to another. This brings alive the intellectual and historical developments that led to Kornai's work on socialist incentives, on the theory of planning, on the economics of shortage, and on the transition from socialism to capitalism. The book takes us on a journey that encompasses large elements of the history of economic thought in the second half of the twentieth century, as well as the history of Central Europe.
Maturation of the 5S rRNA 5′ end is catalyzed in vitro by the endonuclease tRNase Z in the archaeon H. volcanii
Authors: Hölzle Annette , Fischer Susan , Heyer Ruth , Schütz Stefanie , Zacharias Martin , Walther Paul , Allers Thorsten , Marchfelder Anita
Published: March 2008

Ribosomal RNA molecules are synthesized as precursors that have to undergo several processing steps to generate the functional rRNA. The 5S rRNA in the archaeon Haloferax volcanii is transcribed as part of a multicistronic transcript containing both large rRNAs and one or two tRNAs. Release of the 5S rRNA from the precursor requires two endonucleolytic cleavages by enzymes as yet not identified. Here we report the first identification of an archaeal 5S rRNA processing endonuclease. The enzyme tRNase Z, which was initially identified as tRNA processing enzyme, generates not only tRNA 3′ ends but also mature 5S rRNA 5′ ends in vitro. Interestingly, the sequence upstream of the 5S rRNA can be folded into a mini-tRNA, which might explain the processing of this RNA by tRNase Z. The endonuclease is active only at low salt concentrations in vitro, which is in contrast to the 2–4 M KCl concentration present inside the cell in vivo. Electron microscopy studies show that there are no compartments inside the Haloferax cell that could provide lower salt environments. Processing of the 5S rRNA 5′ end is not restricted to the haloarchaeal tRNase Z since tRNase Z enzymes from a thermophilic archaeon, a lower and a higher eukaryote, are as well able to cleave the tRNA-like structure 5′ of the 5S rRNA. Knock out of the tRNase Z gene in Haloferax volcanii is lethal, showing that the protein is essential for the cell.