bluuebunny/crossref_metadata_2025 huggingface dataset:
Creating and Maintaining a High School Physics Research Program
Authors: Horton Robert , Vondracek Mark
Published: August 2004

Perhaps the ultimate challenge a high school (or for that matter college) science student can undertake is independent science research. Research requires a large time commitment and much dedication. In any original and independent study, there are no guarantees that an experiment will even work until one tries. A very small percentage of students get involved in original, challenging research, especially if there is no local college or university where an interested student may go to obtain such an opportunity in a professor's lab. For those relatively few students who do proceed with this type of investigation, the experience can be rewarding and even life changing. This paper provides some recommendations to teachers who have given thought to getting students involved in science research, but have not been able to jump-start a program that can maintain itself over time. Several examples of topics that have led not only to good science but also to local and national recognition for the students will be presented, as well as a brief outline of some top national science competitions where high school students can participate.
More Track and Field
Authors: Fatuzzo Marco , Toepker Terrence P.
Published: August 2004

A recent item in Physics Challenges for Teachers and Students1 presented a problem of a metal rod (mass M) sliding on frictionless, parallel conducting rails (of negligible resistance and separated by a distance L) in the presence of a downwardly directed uniform external magnetic field B. A resistor R bridges the rails, thereby completing the circuit. This problem can also be found in Griffiths' text Introduction to Electrodynamics, 3rd ed. (Problem 7.7).2
The X-ray Shoe Fitter — An Early Application of Roentgen's ‘New Kind of Ray’
Authors: Lapp David R.
Published: August 2004

This paper provides some history of Roentgen's famous discovery of x-rays, a technical review of radiation exposure units, and a history and overview of the risk associated from using or being near one of the earliest of x-ray applications, the x-ray shoe fitter.
Ball on the Edge
Authors: Beeken Paul
Published: August 2004

While performing a simple kinematics experiment that involved rolling a ball off the edge of a table, many of my students observed a systematic error. Specifically, the horizontal component of the ball's velocity when it hit the floor was measured to be consistently higher than the initial velocity it had at the edge of the table. As we increased the initial speed of the ball, effect disappeared. The repeatable nature of the observation demonstrated that what we were seeing was real. Presented here is a discussion of the problem using an analysis accessible to students taking an algebra-based physics class.
Know Your Students
Authors: Knight Randy
Published: August 2004

Welcome to your new role as physics teacher. I hope you will find the suggestions in this column useful as you try to put into practice all the strategies you have learned about teaching. Experienced teachers provide a wealth of ideas to help you develop skills to help your students learn physics. We all want to see you succeed not only at developing your skills as a teacher but also at building a love for the profession that will keep you with us for years to come.

The following suggestions come from Randy Knight, a professor of physics at California Polytechnic State University in San Luis Obispo, CA. He is the author of Five Easy Lessons: Strategies for Successful Physics Teaching and the new textbook Physics for Scientists and Engineers: A Strategic Approach, both published by Addison-Wesley.
Interstellar Turbulence I: Observations and Processes
Authors: Elmegreen Bruce G. , Scalo John
Published: August 2004

▪ Abstract  Turbulence affects the structure and motions of nearly all temperature and density regimes in the interstellar gas. This two-part review summarizes the observations, theory, and simulations of interstellar turbulence and their implications for many fields of astrophysics. The first part begins with diagnostics for turbulence that have been applied to the cool interstellar medium and highlights their main results. The energy sources for interstellar turbulence are then summarized along with numerical estimates for their power input. Supernovae and superbubbles dominate the total power, but many other sources spanning a large range of scales, from swing-amplified gravitational instabilities to cosmic ray streaming, all contribute in some way. Turbulence theory is considered in detail, including the basic fluid equations, solenoidal and compressible modes, global inviscid quadratic invariants, scaling arguments for the power spectrum, phenomenological models for the scaling of higher-order structure functions, the direction and locality of energy transfer and cascade, velocity probability distributions, and turbulent pressure. We emphasize expected differences between incompressible and compressible turbulence. Theories of magnetic turbulence on scales smaller than the collision mean free path are included, as are theories of magnetohydrodynamic turbulence and their various proposals for power spectra. Numerical simulations of interstellar turbulence are reviewed. Models have reproduced the basic features of the observed scaling relations, predicted fast decay rates for supersonic MHD turbulence, and derived probability distribution functions for density. Thermal instabilities and thermal phases have a new interpretation in a supersonically turbulent medium. Large-scale models with various combinations of self-gravity, magnetic fields, supernovae, and star formation are beginning to resemble the observed interstellar medium in morphology and statistical properties. The role of self-gravity in turbulent gas evolution is clarified, leading to new paradigms for the formation of star clusters, the stellar mass function, the origin of stellar rotation and binary stars, and the effects of magnetic fields. The review ends with a reflection on the progress that has been made in our understanding of the interstellar medium and offers a list of outstanding problems.
Dynamics of Lunar Formation
Authors: Canup Robin M.
Published: August 2004

▪ Abstract  The giant impact theory is the leading hypothesis for the origin of the Moon. This review focuses on dynamical aspects of an impact-induced lunar formation, in particular those areas that have advanced considerably in the past decade, including (a) late-stage terrestrial accretion, (b) giant impact simulations, (c) protolunar disk evolution and lunar accretion, and (d) the origin of the initial lunar inclination. In all, recent developments now provide a reasonably consistent dynamical account of the origin of the Moon through a late giant impact with Earth, and suggest that the impact-generation of satellites is likely to be a common process in late-stage solid planet formation.
Fine Structure in Sunspots
Authors: Thomas John H. , Weiss Nigel O.
Published: August 2004

▪ Abstract  Important physical processes on the Sun, and especially in sunspots, occur on spatial scales at or below the limiting resolution of current solar telescopes. Over the past decade, using a number of new techniques, high-resolution observations have begun to reveal the complex thermal and magnetic structure of a sunspot, along with associated flows and oscillations. During this time remarkable advances in computing power have allowed significant progress in our theoretical understanding of the dynamical processes, such as magnetoconvection, taking place within a sunspot. In this review we summarize the latest observational results and theoretical interpretations of the fine structure in sunspots. A number of projects underway to build new solar telescopes or upgrade existing ones, along with several promising new theoretical ideas, ensure that there will be significant advances in sunspot research over the coming decade.
Abundance Variations within Globular Clusters
Authors: Gratton Raffaele , Sneden Christopher , Carretta Eugenio
Published: August 2004

▪ Abstract  Abundance variations within globular clusters (GCs), and of GC stars with respect to field stars, are important diagnostics of a variety of physical phenomena, related to the evolution of individual stars, mass transfer in binary systems, and chemical evolution in high density environments. The broad astrophysical implications of GCs as building blocks of our knowledge of the Universe make a full understanding of their history and evolution basic in a variety of astrophysical fields. We review the current status of the research in this field, comparing the abundances in GCs with those obtained for field stars, discussing in depth the evidence for H-burning at high temperatures in GC stars, describing the process of self-enrichment in GCs with particular reference to the case of the most massive Galactic GC (ω Cen), and discussing various classes of cluster stars with abundance anomalies. Whereas the overall pattern might appear very complex at first sight, exciting new scenarios are opening where the interplay between GC dynamical and chemical properties are closely linked with each other.
Planet Formation by Coagulation: A Focus on Uranus and Neptune
Authors: Goldreich Peter , Lithwick Yoram , Sari Re'em
Published: August 2004

▪ Abstract  Planets form in the circumstellar disks of young stars. We review the basic physical processes by which solid bodies accrete each other and alter each others' random velocities, and we provide order-of-magnitude derivations for the rates of these processes. We discuss and exercise the two-groups approximation, a simple yet powerful technique for solving the evolution equations for protoplanet growth. We describe orderly, runaway, neutral, and oligarchic growth. We also delineate the conditions under which each occurs. We refute a popular misconception by showing that the outer planets formed quickly by accreting small bodies. Then we address the final stages of planet formation. Oligarchy ends when the surface density of the oligarchs becomes comparable to that of the small bodies. Dynamical friction is no longer able to balance viscous stirring and the oligarchs' random velocities increase. In the inner-planet system, oligarchs collide and coalesce. In the outer-planet system, some of the oligarchs are ejected. In both the inner- and outer-planet systems, this stage ends once the number of big bodies has been reduced to the point that their mutual interactions no longer produce large-scale chaos. Subsequently, dynamical friction by the residual small bodies circularizes and flattens their orbits. The final stage of planet formation involves the clean up of the residual small bodies. Clean up has been poorly explored.
Astrophysics with Presolar Stardust
Authors: Clayton Donald D. , Nittler Larry R.
Published: August 2004

▪ Abstract  Meteorites and interplanetary dust particles contain presolar stardust grains: solid samples of stars that can be studied in the laboratory. The stellar origin of the grains is indicated by enormous isotopic ratio variations compared with Solar System materials, explainable only by nuclear reactions occurring in stars. Known presolar phases include diamond, SiC, graphite, Si3N4, Al2O3, MgAl2O4, CaAl12O19, TiO2, Mg(Cr,Al)2O4, and most recently, silicates. Subgrains of refractory carbides (e.g., TiC), and Fe-Ni metal have also been observed within individual presolar graphite grains. We review the astrophysical implications of these grains for the sciences of nucleosynthesis, stellar evolution, grain condensation, and the chemical and dynamic evolution of the Galaxy. Unique scientific information derives primarily from the high precision (in some cases <1%) of the measured isotopic ratios of large numbers of elements in single stardust grains. Stardust science is just now reaching maturity and will play an increasingly important role in nucleosynthesis applications.
Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
Authors: Kormendy John , Kennicutt Robert C.
Published: August 2004

▪ Abstract  The Universe is in transition. At early times, galactic evolution was dominated by hierarchical clustering and merging, processes that are violent and rapid. In the far future, evolution will mostly be secular—the slow rearrangement of energy and mass that results from interactions involving collective phenomena such as bars, oval disks, spiral structure, and triaxial dark halos. Both processes are important now. This review discusses internal secular evolution, concentrating on one important consequence, the buildup of dense central components in disk galaxies that look like classical, merger-built bulges but that were made slowly out of disk gas. We call these pseudobulges.

We begin with an “existence proof”—a review of how bars rearrange disk gas into outer rings, inner rings, and stuff dumped onto the center. The results of numerical simulations correspond closely to the morphology of barred galaxies. In the simulations, gas is transported to small radii, where it reaches high densities and plausibly feeds star formation. In the observations, many barred and oval galaxies have dense central concentrations of gas and star formation. Optical colors and spectra often imply young stellar populations. So the formation of pseudobulges is well supported by theory and observations. It is embedded in a broader evolution picture that accounts for much of the richness observed in galaxy structure.

If secular processes built dense central components that masquerade as bulges, how can we distinguish them from merger-built bulges? Observations show that pseudobulges retain a memory of their disky origin. That is, they have one or more characteristics of disks: (a) flatter shapes than those of classical bulges, (b) correspondingly large ratios of ordered to random velocities, (c) small velocity dispersions σ with respect to the Faber-Jackson correlation between σ and bulge lumi nosity, (d) spiral structure or nuclear bars in the “bulge” part of the light profile, (e) nearly exponential brightness profiles, and ( f ) starbursts. All these structures occur preferentially in barred and oval galaxies, where secular evolution should be most rapid. So the cleanest examples of pseudobulges are recognizable.

Are their formation timescales plausible? We use measurements of central gas densities and star-formation rates to show that pseudobulges of the observed densities form on timescales of a few billion years.

Thus a large variety of observational and theoretical results lead to a new picture of galaxy evolution that complements hierarchical clustering and merging. Secular evolution consists of more than the aging of stellar populations. Every galaxy is dynamically evolving.
GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems
Authors: Fender Rob , Belloni Tomaso
Published: August 2004

▪ Abstract  GRS 1915+105—the first stellar-scale, highly relativistic jet source identified—is a key system for our understanding of the disc-jet coupling in accreting black hole systems. Comprehending the coupling between inflow and outflow in this source not only is important for X-ray binary systems but has a broader relevance for studies of active galactic nuclei and gamma-ray bursts. In this paper, we present a detailed review of the observational properties of the system, as established in the decade since its discovery. We attempt to place it in context by a detailed comparison with other sources, and construct a simple model for the disc-jet coupling, which may be more widely applicable to accreting black hole systems.
The First Stars
Authors: Bromm Volker , Larson Richard B.
Published: August 2004

▪ Abstract  We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. In particular, we discuss the initial conditions for Population III star formation, as given by variants of the cold dark matter cosmology. Numerical simulations have investigated the collapse and the fragmentation of metal-free gas, showing that the first stars were predominantly very massive. The exact determination of the stellar masses, and the precise form of the primordial initial mass function, is still hampered by our limited understanding of the accretion physics and the protostellar feedback effects. We address the importance of heavy elements in bringing about the transition from an early star formation mode dominated by massive stars to the familiar mode dominated by low-mass stars at later times. We show how complementary observations, both at high redshifts and in our local cosmic neighborhood, can be utilized to probe the first epoch of star formation.
Impulsive Magnetic Reconnection in the Earth's Magnetotail and the Solar Corona
Authors: Bhattacharjee A.
Published: August 2004

▪ Abstract  Impulsive reconnection dynamics is characterized not only by fast growth but also by a sudden change in the time derivative of the growth rate. I review recent developments in the theory and simulation of forced impulsive reconnection based on the equations of resistive and Hall magnetohydrodynamics (MHD). Impulsive reconnection can be realized in resistive as well as Hall MHD by the imposition of suitable boundary conditions. However, compared with resistive MHD, Hall MHD reconnection is distinguished by qualitatively different magnetic field and electron and ion signatures in the reconnection layer. Furthermore, nonlinear reconnection rates in Hall MHD are weakly dependent on the Lundquist number. I discuss applications of the physics of impulsive reconnection to substorms in the Earth's magnetotail and solar flares.
Young Stars Near the Sun
Authors: Zuckerman B. , Song Inseok
Published: August 2004

▪ Abstract  Until the late 1990s the rich Hyades and the sparse UMa clusters were the only coeval, comoving concentrations of stars known within 60 pc of Earth. Both are hundreds of millions of years old. Then beginning in the late 1990s the TW Hydrae Association, the Tucana/Horologium Association, the β Pictoris Moving Group, and the AB Doradus Moving Group were identified within ∼60 pc of Earth, and the η Chamaeleontis cluster was found at 97 pc. These young groups (ages 8–50 Myr), along with other nearby, young stars, will enable imaging and spectroscopic studies of the origin and early evolution of planetary systems.
Interstellar Turbulence II: Implications and Effects
Authors: Scalo John , Elmegreen Bruce G.
Published: August 2004

▪ Abstract  Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small-scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations. The theory of diffraction and refraction as well as the main observations and scintillation regions are reviewed.
Enhancing active learning in the student laboratory
Authors: Modell Harold I. , Michael Joel A. , Adamson Tom , Horwitz Barbara
Published: August 2004

Modell, Harold I., Joel A. Michael, Tom Adamson, and Barbara Horwitz. Enhancing active learning in the student laboratory. We previously examined how three approaches to directing students in a laboratory setting impacted their ability to repair a faulty mental model in respiratory physiology (Modell, HI, Michael JA, Adamson T, Goldberg J, Horwitz BA, Bruce DS, Hudson ML, Whitescarver SA, and Williams S. Adv Physiol Educ 23: 82–90, 2000). This study addresses issues raised by the results of that work. In one group, a written protocol directed students to predict what would happen to frequency and depth of breathing during exercise on a bicycle ergometer, run the experiment, and compare their results to their predictions (“predictor without verification”). In a “predictor with verification” group, students followed the same written protocol but were also required to show the instructor their predictions before running the experiment. Students in a third group reported their predictions verbally to an instructor immediately before exercise and reviewed their results with that instructor immediately after exercise (“instructor intervention group”). Results of this study were consistent with our earlier work. The predictor with verification and predictor without verification protocols yielded similar results. The instructor intervention protocol yielded higher success rates in repairing students’ mental models. We subsequently assessed the efficacy of a prediction period at the beginning of the lab session and a wrap-up period at the end to compare predictions and results. This predict and wrap-up protocol was more effective than the predictor without verification protocol, but it was not as effective as the instructor intervention protocol. Although these results may reflect multiple factors impacting learning in the student laboratory, we believe that a major factor is a mismatch between students’ approaches to learning and the intended learning outcomes of the experience.
Programmed cell death protein 4 suppresses CDK1/cdc2 via induction of p21Waf1/Cip1
Authors: Göke R. , Barth P. , Schmidt A. , Samans B. , Lankat-Buttgereit B.
Published: August 2004

We show that the recently discovered tumor suppressor pdcd4 represses the transcription of the mitosis-promoting factor cyclin-dependent kinase (CDK)1/cdc2 via upregulation of p21Waf1/Cip1. p21Waf1/Cip1 inhibits CDK4/6 and CDK2. Decrease of CDK4/6 and CDK2 enhances the binding of pRb to E2F/DP, which in turn together bind to and repress the cdc2 promoter. Upregulation of CDK1/cdc2 accompanied by a malignant change was previously reported in colon cancer. We show that expression of pdcd4 as an indirect suppressor of CDK1/cdc2 is lost in progressed carcinomas of lung, breast, colon, and prostate. Furthermore, it seems that localization and expression of pdcd4 directly correlate with tumor progression. Finally, the CDK1/cdc2 inhibitor roscovitine reduces the proliferation of several tumor cell lines, suggesting that inhibition of CDK1/cdc2 may be a useful strategy against malignant transformation. Therefore, pdcd4 might serve as a novel target for antineoplastic therapies.
Chronic β-adrenoreceptor activation increases cardiac cavity size through chamber remodeling and not via modifications in myocardial material properties
Authors: Gibbs Mark , Veliotes Demetri G. A. , Anamourlis Christopher , Badenhorst Danelle , Osadchii Oleg , Norton Gavin R. , Woodiwiss Angela J.
Published: August 2004

Chronic β-adrenoreceptor (β-AR) activation increases left ventricular (LV) cavity size by promoting a rightward shift in LV diastolic pressure-volume (P-V) relations in association with increases in low-tensile strength myocardial (non-cross-linked) collagen concentrations. Because diastolic P-V relations are determined by chamber remodeling as well as by myocardial material properties (indexed by myocardial stiffness), both of which are associated with modifications in myocardial collagen cross-linking, we evaluated whether chamber remodeling or alterations in myocardial material properties govern β-AR-mediated modifications in diastolic P-V relations. The effects of chronic administration of isoproterenol (Iso; 0.04 mg·kg−1·day−1 from 12 to 19 mo of age) to spontaneously hypertensive rats (SHRs) on LV cavity dimensions, LV diastolic P-V relations, myocardial collagen characteristics, myocardial stiffness constants [e.g., the slope of the LV diastolic stress-strain relation ( k)], and LV chamber and myocardial systolic function were assessed. SHRs at 19 mo of age had normal LV diastolic P-V relations, marked myocardial fibrosis (using a pathological score), increased myocardial cross-linked (insoluble to cyanogen bromide digestion) type I and type III collagen concentrations, and enhanced myocardial k values. Iso administration to SHRs resulted in enlarged LV cavity dimensions mediated by a rightward shift in LV diastolic P-V relations, increased volume intercept of the LV diastolic P-V relation, decreased LV relative wall thickness despite a tendency to augment LV hypertrophy, and increased non-cross-linked type I and type III myocardial collagen concentrations. Iso administration resulted in reduced pump function without modification of intrinsic myocardial systolic function. However, despite increasing myocardial non-cross-linked concentrations, Iso failed to alter myocardial k in SHRs. These results suggest that β-AR-mediated rightward shifts in LV diastolic P-V relations, which induce decreased pump function, are mediated by chamber remodeling but not by modifications in myocardial material properties.
Molecular characterization of an inward rectifier channel (IKir) found in avian vestibular hair cells: cloning and expression of pKir2.1
Authors: Correia Manning J. , Wood Thomas G. , Prusak Deborah , Weng Tianxiang , Rennie Katherine J. , Wang Hui-Qun
Published: August 2004

A fast inwardly rectifying current has been observed in some of the sensory cells (hair cells) of the inner ear of several species. While the current was presumed to be an IKir current, contradictory evidence existed as to whether the cloned channel actually belonged to the Kir2.0 subfamily of potassium inward rectifiers. In this paper, we report for the first time converging evidence from electrophysiological, biochemical, immunohistochemical, and genetic studies that show that the Kir2.1 channel carries the fast inwardly rectifying currents found in pigeon vestibular hair cells. Following cytoplasm extraction from single type II and multiple pigeon vestibular hair cells, mRNA was reverse transcribed, amplified, and sequenced. The open reading frame (ORF), consisting of a 1,284-bp nucleotide sequence, showed 94, 85, and 83% identity with Kir2.1 subunit sequences from chick lens, Kir2 sequences from human heart, and a mouse macrophage cell line, respectively. Phylogenetic analyses revealed that pKir2.1 formed an immediate node with hKir2.1 but not with hKir2.2–2.4. Hair cells (type I and type II) and supporting cells in the sensory epithelium reacted positively with a Kir2.1 antibody. The whole cell current recorded in oocytes and CHO cells, transfected with pigeon hair cell Kir2.1 (pKir2.1), demonstrated blockage by Ba2+ and sensitivity to changing K+ concentration. The mean single-channel linear slope conductance in transfected CHO cells was 29 pS. The open dwell time was long (∼300 ms at −100 mV), and the closed dwell time was short (∼34 ms at −100 mV). Multistates ranging from 3–6 were noted in some single-channel responses. All of the above features have been described for other Kir2.1 channels. Current clamp studies of native pigeon vestibular hair cells illustrated possible physiological roles of the channel and showed that blockage of the channel by Ba2+ depolarized the resting membrane potential by ∼30 mV. Negative currents hyperpolarized the membrane ∼20 mV before block but ∼60 mV following block. RT-PCR studies revealed that the pKir2.1 channels found in pigeon vestibular hair cells were also present in pigeon vestibular nerve, vestibular ganglion, lens, neck muscle, brain (brain stem, cerebellum and optic tectum), liver, and heart.
Maternal Hyperglycemia Improves Fetal Cardiac Function During Tachycardia-Induced Heart Failure in Pigs
Authors: Schmidt M.R. , Smerup M. , Kristiansen S.B. , Bøtker H.E. , Schmitz O. , Hjortdal V.E. , Sørensen K.E. , Redington A.N.
Published: August 2004

Background—

Fetal tachycardia often leads to cardiac failure, which in experimental settings can be prevented by direct fetal glucose-insulin administration. In this study, we hypothesize that similar effects can be obtained indirectly by inducing maternal hyperglycemia.

Methods and Results—

Systolic and diastolic indices (dP/dt
max
and τ) of left ventricular function were measured by use of high-fidelity catheters during 180 minutes of aggressive atrial pacing (≈300 bpm) in 12 preterm porcine fetuses. In 6 fetuses, maternal hyperglycemia (15 mmol/L) was induced for the last 120 minutes of pacing. The remaining fetuses served as controls. Glucose, insulin, and free fatty acid levels were determined, as was fetal myocardial glycogen content. Maternal glucose infusion led to significant fetal hyperglycemia and hyperinsulinemia but did not change the inherently low fetal levels of free fatty acids. There were no differences between groups with regard to dP/dt
max
(1025±226 and 1037±207 mm Hg,
P
=NS) and τ (20.6±2.0 and 21.4±1.6 ms,
P
=NS) at baseline (100%). During the 180 minutes of pacing, systolic function (dP/dt
max
) and diastolic function (τ) deteriorated more in the control group than in the hyperglycemic group (
P
<0.001 for both). At 180 minutes, dP/dt
max
was 62±18% of baseline in controls and 85±11% in hyperglycemic fetuses (
P
=0.03), and τ was 117±12% and 98±4%, respectively (
P
=0.004).

Conclusions—

Induced maternal hyperglycemia improves fetal cardiac function during fetal tachycardia and suggests a possible additional therapeutic option to improve the function of the failing fetal heart before or during antiarrhythmic therapy. The findings may be relevant in fetal heart failure in general.
Recombinant Glucagon-Like Peptide-1 Increases Myocardial Glucose Uptake and Improves Left Ventricular Performance in Conscious Dogs With Pacing-Induced Dilated Cardiomyopathy
Authors: Nikolaidis Lazaros A. , Elahi Dariush , Hentosz Teresa , Doverspike Aaron , Huerbin Rhonda , Zourelias Lee , Stolarski Carol , Shen You-tang , Shannon Richard P.
Published: August 2004

Background—

The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol. We examined the impact of recombinant GLP-1 (rGLP-1) on LV and systemic hemodynamics and myocardial substrate uptake in conscious dogs with advanced dilated cardiomyopathy (DCM) as a mechanism for overcoming myocardial insulin resistance and enhancing myocardial glucose uptake.

Methods and Results—

Thirty-five dogs were instrumented and studied in the fully conscious state. Advanced DCM was induced by 28 days of rapid pacing. Sixteen dogs with advanced DCM received a 48-hour infusion of rGLP-1 (1.5 pmol · kg
−1
· min
−1
). Eight dogs with DCM served as controls and received 48 hours of a saline infusion (3 mL/d). Infusion of rGLP-1 was associated with significant (
P
<0.02) increases in LV dP/dt (98%), stroke volume (102%), and cardiac output (57%) and significant decreases in LV end-diastolic pressure, heart rate, and systemic vascular resistance. rGLP-1 increased myocardial insulin sensitivity and myocardial glucose uptake. There were no significant changes in the saline control group.

Conclusions—

rGLP-1 dramatically improved LV and systemic hemodynamics in conscious dogs with advanced DCM induced by rapid pacing. rGLP-1 has insulinomimetic and glucagonostatic properties, with resultant increases in myocardial glucose uptake. rGLP-1 may be a useful metabolic adjuvant in decompensated heart failure.
Continuous Autonomic Assessment in Patients With Symptomatic Heart Failure
Authors: Adamson Philip B. , Smith Andrew L. , Abraham William T. , Kleckner Karen J. , Stadler Robert W. , Shih Alex , Rhodes Melissa M.
Published: August 2004

Background—

Heart rate variability (HRV) as an indirect autonomic assessment provides prognostic information when measured over short time periods in patients with heart failure. Long-term continuous HRV can be measured from an implantable device, but the clinical value of these measurements is unknown.

Methods and Results—

A total of 397 patients with New York Heart Association class III or IV heart failure were studied. Of these, 370 patients had information from their implanted cardiac resynchronization device for mortality risk stratification, and 288 patients had information for measured parameters (ie, HRV, night heart rate, and patient activity) and clinical event analyses. Continuous HRV was measured as the standard deviation of 5-minute median atrial-atrial intervals (SDAAM) sensed by the device. SDAAM <50 ms when averaged over 4 weeks was associated with increased mortality risk (hazard ratio 3.20,
P
=0.02) and SDAAM were persistently lower over the entire follow-up period in patients who required hospitalization or died. SDAAM decreased a median of 16 days before hospitalization and returned to baseline after treatment. Automated detection of decreases in SDAAM was 70% sensitive in detecting cardiovascular hospitalization, with 2.4 false-positives per patient-year of follow-up.

Conclusions—

This study demonstrates that SDAAM continuously measured from an implanted cardiac resynchronization device is lower in patients at high mortality and hospitalization risk. SDAAM declines as patient status decompensates. Continuous long-term SDAAM may be a useful tool in the clinical management of patients with chronic heart failure.
Integrin Profile and In Vivo Homing of Human Smooth Muscle Progenitor Cells
Authors: Deb Arjun , Skelding Kimberly A. , Wang Shaohua , Reeder Margo , Simper David , Caplice Noel M.
Published: August 2004

Background—

Recently, we identified circulating smooth muscle progenitor cells (SPCs) in human peripheral blood. The integrin profile of such progenitors is currently unknown and may affect their in vivo homing characteristics. In this study, we determined the integrin profile of vascular progenitors and SPC adhesion to extracellular matrix (ECM) proteins in vitro and in vivo.

Methods and Results—

SPCs and endothelial progenitor cells (EPCs) were isolated from peripheral blood of healthy human subjects, and expression of surface integrins and adhesion to several vascular ECM proteins were determined. Homing of SPCs in vivo to specific ECM protein was determined by intracoronary infusion of fluorescent SPCs into porcine coronary arteries containing a fibronectin-coated mesh stent. SPCs had high expression of β
1
integrin, moderate expression of α
1
, low levels of α
v
β
3
, and did not express α
v
β
5
, β
2
, α
2
β
1
, or α
4
β
1
integrins. In contrast, EPCs had high expression of α
2
β
1
, α
v
β
3
, α
v
β
5
, β
1
, and α
1
and minimal expression of α
4
β
1
. Moreover, SPCs showed increased adherence to fibronectin and collagen type I compared with vitronectin, consistent with their integrin profile, and demonstrated a similar degree of in vivo attachment to fibronectin-coated mesh.

Conclusions—

These data for the first time show a spectrum of integrin expression on vascular progenitors and suggest the potential importance of integrins in mediating adherence of SPCs to specific ECM both in vitro and in vivo.
Beneficial Effects of Chronic Pharmacological Manipulation of β-Adrenoreceptor Subtype Signaling in Rodent Dilated Ischemic Cardiomyopathy
Authors: Ahmet Ismayil , Krawczyk Melissa , Heller Phillip , Moon Chanil , Lakatta Edward G. , Talan Mark I.
Published: August 2004

Background—

Studies in isolated cardiac myocytes have demonstrated that signaling via specific β
1
-adrenergic receptor subtypes (β
1
ARs) promotes but that signaling via β
2
ARs protects from cell death. We hypothesized that prolonged β
2
AR stimulation or β
1
AR blockade would each protect myocytes from death and thereby ameliorate cardiac remodeling in chronic heart failure.

Methods and Results—

A large myocardial infarction (MI) induced in rats by coronary artery ligation resulted in a dilated cardiomyopathy (DCM) characterized by infarct expansion and a progressive increase in left ventricular (LV) end-diastolic volume, accompanied by a reduction in ejection fraction (EF), as assessed by repeated echocardiography. Pressure-volume analysis at 8 weeks after ligation showed that diastolic stiffness (Eed) and arterial elastance (Ea) were increased, end-systolic elastance (Ees) was decreased, and arterioventricular (AV) coupling (Ea/Ees) had deteriorated. Apoptosis was present in both peri-infarct and remote myocardium. Chronic (6-week) administration of the β
2
AR agonists fenoterol or zinterol, starting at 2 weeks after MI, reduced the extent of LV dilation, infarct expansion, and EF decline. The β
1
AR blocker metoprolol did not affect the former and preserved EF to a lesser extent than did the β
2
AR agonists. At 8 weeks after ligation, apoptosis was reduced by all drugs but to a greater extent by β
2
AR agonists than by the β
1
AR blocker. Both β
2
AR agonists and the β
1
AR blocker improved AV coupling, the former mainly by reducing Ea and the latter mainly by increasing Ees. Only the β
2
AR agonists reduced the Eed and the MI size by reducing infarct expansion.

Conclusions—

These results provide proof of concept for the efficacy of chronic β
2
AR stimulation in this DCM model.
Prevalence of Fabry Disease in Female Patients With Late-Onset Hypertrophic Cardiomyopathy
Authors: Chimenti Cristina , Pieroni Maurizio , Morgante Emanuela , Antuzzi Daniela , Russo Andrea , Russo Matteo Antonio , Maseri Attilio , Frustaci Andrea
Published: August 2004

Background—

Fabry disease (FD) has been recognized as the cause of left ventricular hypertrophy in 6% of men with late-onset hypertrophic cardiomyopathy (HCM). Although FD is considered a recessive X-linked disorder, affected women are increasingly reported. The aim of our study was to determine the prevalence of FD in female patients with HCM.

Methods and Results—

Thirty-four consecutive women (mean age, 50±13.6 years) who received an ECG and echocardiographic diagnosis of HCM were submitted to an invasive cardiac study that included a biventricular endomyocardial biopsy. Tissue samples were analyzed for histology and electron microscopy. Peripheral blood activity of α-galactosidase (α-Gal) A was assessed in all patients. None of them had a family history of FD. Histology and electron microscopy showed in 4 patients (12%; mean age, 51.5±3.9 years) the presence of cell vacuoles characterized by the accumulation of glycolipid material organized in concentric lamellar structures, diagnostic for FD. In the remaining patients, histology was consistent with HCM. In all the female carriers, the heart was the only organ clinically involved in the disease, showing concentric hypertrophy in 2 patients, asymmetric hypertrophy in 1, and apical hypertrophy in 1. The α-Gal A enzymatic activity was 44±14% of control values. Genetic analysis showed the presence of α-Gal A gene mutation in all 4 cases.

Conclusions—

FD may account for up to 12% of females with late-onset HCM. Those heterozygous for FD with left ventricular hypertrophy are potential candidates for enzyme enhancement/replacement therapy.
Laminar Flow Activates Peroxisome Proliferator-Activated Receptor-γ in Vascular Endothelial Cells
Authors: Liu Yi , Zhu Yi , Rannou Francois , Lee Tzong-Shyuan , Formentin Kitty , Zeng Lingfang , Yuan Xiaohui , Wang Nanping , Chien Shu , Forman Barry M. , Shyy John Y.-J.
Published: August 2004

Background—

Steady laminar flow is atheroprotective, in part because of its antiinflammatory effects on vascular endothelial cells (ECs). We studied the activation of peroxisome proliferator-activated receptor-γ (PPARγ) in ECs in response to laminar flow and the associated antiinflammatory effect.

Methods and Results—

Using flow channel with cultured ECs, we found that laminar flow activated the PPARγ-mediated PPAR-responsive element (PPRE) activity and increased the mRNA encoding CD36, a PPARγ-targeted gene. Analysis of the CD36 promoter revealed that PPRE was required for flow activation. Laminar flow induced the GAL-PPARγ-LBD fusion protein, which suggests that flow activation of PPARγ was ligand dependent. The pharmaceutical inhibitors of phospholipase A2 (PLA2) and cytochrome P450 epoxygenases (CYP450s) were able to block the laminar flow-activated PPARγ. We also showed that lipid extracts from flow media contained ligands for the activation of PPARγ in other cell types. This paracrine activation exerted antiinflammatory effects in ECs and THP-1 cells, including the suppression of cytokine-induced nuclear factor-κB activation and expression of intercellular adhesion molecule-1.

Conclusions—

Laminar flow activates endogenous PPARγ in ECs, which is ligand dependent. The flow production of PPARγ ligands is through the PLA2-CYP450 pathway, and the induced PPARγ ligands exert antiinflammatory effects in several types of cells.
Comparison of Coronary Plaque Rupture Between Stable Angina and Acute Myocardial Infarction
Authors: Hong Myeong-Ki , Mintz Gary S. , Lee Cheol Whan , Kim Young-Hak , Lee Seung-Whan , Song Jong-Min , Han Ki-Hoon , Kang Duk-Hyun , Song Jae-Kwan , Kim Jae-Joong , Park Seong-Wook , Park Seung-Jung
Published: August 2004

Background—

We evaluated the incidence and predictors of single and multiple plaque ruptures in acute myocardial infarction (AMI) and stable angina pectoris (SAP).

Methods and Results—

We performed 3-vessel intravascular ultrasound (IVUS) examination in 235 patients: 122 had AMI, and 113 had SAP. Plaque rupture of infarct-related or target lesions occurred in 80 AMI patients (66%) and in 31 SAP patients (27%) (
P
<0.001). Non–infarct-related or non–target artery plaque ruptures occurred in 21 AMI patients (17%) and 6 SAP patients (5%) (
P
=0.008). Multiple plaque ruptures were observed in 24 AMI (20%) and 7 SAP patients (6%) (
P
=0.004). Therefore, at least 1 plaque rupture in any coronary artery was noted in 84 AMI patients (69%) and 35 SAP patients (31%) (
P
<0.001). Overall, the only independent clinical predictor of plaque rupture in the infarct-related/target lesion was AMI (
P
<0.01; OR, 4.867; 95% CI, 2.734 to 8.661). The only independent clinical predictor of plaque rupture in AMI patients was an elevated C-reactive protein (CRP) level (
P
=0.035; OR, 2.139; 95% CI, 1.053 to 4.343). Conversely, in SAP patients, the only independent clinical predictor of plaque rupture was diabetes mellitus (
P
=0.034; OR, 2.553; 95% CI, 1.071 to 6.085). The only independent clinical predictor of multiple plaque ruptures was AMI (
P
=0.003; OR, 3.752; 95% CI, 1.546 to 9.105).

Conclusions—

Three-vessel IVUS imaging showed that culprit lesion plaque rupture, secondary remote plaque ruptures, and multiple plaque ruptures were all more common in AMI patients than SAP patients. In AMI patients, plaque rupture was associated with a high CRP level, whereas in SAP patients, plaque rupture was more common in those with diabetes.
Left Ventricular Assist Device as Destination for Patients Undergoing Intravenous Inotropic Therapy
Authors: Stevenson Lynne Warner , Miller Leslie W. , Desvigne-Nickens Patrice , Ascheim Deborah D. , Parides Michael K. , Renlund Dale G. , Oren Ronald M. , Krueger Steven K. , Costanzo Maria Rosa , Wann L. Samuel , Levitan Ronald G. , Mancini Donna
Published: August 2004

Background—

Left ventricular assist devices (LVADs) have improved survival in patients with end-stage heart failure. Compared with previous trials, the Randomized Evaluation of Mechanical Assistance in Treatment of Chronic Heart Failure (REMATCH) trial enrolled patients with more advanced heart failure and high prevalence of intravenous inotropic therapy. This study analyzes, on a post hoc basis, outcomes in patients undergoing inotropic infusions at randomization.

Methods and Results—

Of 129 patients randomized, 91 were receiving intravenous inotropic therapy at randomization to LVAD or optimal medical management (OMM). Mean systolic pressure was 100 versus 107 mm Hg in those not receiving inotropes, serum sodium was 134 versus 137 mEq/L, and left ventricular ejection fraction was 17% for both groups. LVADs improved survival throughout follow-up for patients undergoing baseline inotropic infusions (
P
=0.0014); for the LVAD group versus the OMM group, respectively, 6-month survival was 60% versus 39%, 1-year survival rates were 49% versus 24%, and 2-year survival rates were 28% versus 11%. For 38 patients not undergoing inotropic infusions, 6-month survival was 61% for those with LVADs and 67% for those with OMM, whereas 1-year rates were 57% and 40%, respectively (
P
=0.55). Quality-of-life scores for survivors improved. Median days out of hospital for patients on inotropic therapy at randomization were 255 with LVAD and 105 with OMM.

Conclusions—

Despite severe compromise, patients undergoing inotropic infusions at randomization derived major LVAD survival benefit with improved quality of life. Patients not undergoing inotropic infusions had higher survival rates both with and without LVAD, but differences did not reach significance. Future studies should prespecify analyses of inotropic and other therapies to determine how disease severity and parallel medical treatment influence the benefits offered by mechanical circulatory support.
Xuezhikang, an Extract of Cholestin, Protects Endothelial Function Through Antiinflammatory and Lipid-Lowering Mechanisms in Patients With Coronary Heart Disease
Authors: Zhao Shui Ping , Liu Ling , Cheng Yan Chun , Shishehbor Mehdi H. , Liu Ming Hui , Peng Dao Quan , Li Yu Ling
Published: August 2004

Background—

Endothelial dysfunction is associated with inflammation and postprandial hypertriglyceridemia. Xuezhikang, an extract of Cholestin, a dietary supplement, has lipid-modulating and antiinflammatory effects. We explored the effects of xuezhikang on endothelial function and high-sensitivity C-reactive protein (hs-CRP) in patients with coronary heart disease (CHD).

Methods and Results—

We prospectively randomized 50 CHD patients to xuezhikang 1200 mg/d or placebo for 6 weeks. Fasting hs-CRP concentrations, flow-mediated vasodilation (FMD) at 0 and 4 hours, and lipid parameters at 0, 2, 4, and 6 hours were monitored after a high-fat meal (800 calories; 50 g fat) in all patients. All patients underwent a high-fat meal test at the beginning of the study and after 6 weeks of treatment. Postprandial FMD was significantly worse at 4 hours after a high-fat meal (
P
<0.05), and this was associated with the area under the triglyceride curve (TG-AUC) (
r
=0.345,
P
<0.01). After 6 weeks of xuezhikang, fasting hs-CRP levels and TG-AUC (
P
<0.001 for each) decreased. Furthermore, preprandial and postprandial FMD significantly improved (
P
<0.001). There were no significant changes in serum lipids and FMD in the placebo arm. In multivariable regression analysis, changes in TG-AUC and fasting hs-CRP levels were predictive of improvement in preprandial FMD (
P
<0.05).

Conclusions—

Xuezhikang effectively improved preprandial and postprandial endothelial function through its potent antiinflammatory and lipid-lowering effects.