bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation Resistant Low Bandgap InGaAsP Solar Cell for Multi-Junction Solar Cells
Authors: Khan Aurangzeb , Yamaguchi Masafumi , Dharmaras Nathaji , Yamada Takashi , Tanabe Tatsuya , Takagishi Shigenori , Itoh Hisayoshi , Ohshima Takeshi , Imaizumi Mitsuru , Matsuda Sumio
Published: October 2002

We have explored the superior radiation tolerance of metal organic chemical vapor deposition (MOCVD) grown, low bandgap, (0.95 eV) InGaAsP solar cells as compared to GaAs-on-Ge cells, after 1 MeV electron irradiation. The minority carrier injection due to forward bias and light illumination under low concentration ratio, can lead to enhanced recovery of radiation damage in InGaAsP n+-p junction solar cells. An injection anneal activation energy (0.58 eV) of the defects involved in damage/recovery of the InGaAsP solar cells has been estimated from the resultant recovery of the solar cell properties following minority carrier injection. The results suggest that low bandgap radiation resistant InGaAsP (0.95 eV) lattice matched to InP substrates provide an alternative to use as bottom cells in multi-junction solar cells instead of less radiation ressitant conventional GaAs based solar cells for space applications.
Green InGaN Light-Emitting Diodes Grown on Silicon (111) by Metalorganic Vapor Phase Epitaxy
Authors: Feltin Eric , Dalmasso Stéphane , de Mierry Philippe , Beaumont Bernard , Lahrèche Hacène , Bouillé Agnès , Haas Helge , Leroux Mathieu , Gibart Pierre
Published: October 2002

We report on the growth and characterization of green InGaN light-emitting diodes (LEDs) grown on Si (111) substrates using metalorganic vapor phase epitaxy. A single InGaN quantum well active layer has been used. The optical qualities of InGaN on Si(111) and the p–doping efficiency of GaN are discussed. The turn-on voltage of the LED is 6.8 V and the operating voltage is 10.7 V at 20 mA. Electroluminescence of the LEDs starts at a forward bias of 3.5 V. The electroluminescence peaks at 508 nm, with a full-width at half maximum of 52 nm. An optical output power of 6 µW (in ∼ 8π/5 sr) was achieved for an applied current of 20 mA.
Calculation of Ballooning Mode Stability Boundary in the GAMMA10 Tandem Mirror
Authors: Shiotani Kensuke , Katanuma Isao , Ito Toru , Nakashima Yousuke , Yatsu Kiyoshi
Published: October 2002

The GAMMA10 tandem mirror contains non-axisymmetric magnetic mirror region (anchor cell) for magnetohydrodynamic (MHD) stability. We determined numerically the boundary of MHD stability when a neutral beam from recently installed neutral beam injector is injected in the anchor region.
Hollowing and Transfer of Polymethyl Methacrylate Film Propelled by Laser Ablation of Triazeno Polymer Film
Authors: Mito Takashi , Tsujita Takuji , Masuhara Hiroshi , Hayashi Nobuaki , Suzuki Kenkichi
Published: October 2002

Utilizing the laser ablation of a triazeno polymer (TA) film as a driving force, materials transfer and patterning were successfully demonstrated. The prepared overlaid films consist of a source film, which is made of pyrene-doped polymethyl methacrylate (PMMA) and TA films, and a target neat PMMA film on a quartz plate. After pressing them together, a 248 nm laser pulse was irradiated from the back side of the source film. When the thickness of the TA film was 1.0 µm, slightly thicker than the penetration depth of TA of 600 nm, the pyrene-doped PMMA film was perfectly transferred to the target film.
Rugged Metal Electrode (RME) for High Density Memory Devices
Authors: Joo Jae-Hyun , Kim Wan-Don , Jeong Yong-Kuk , Won Seok-Jun , Park Soon-Yeon , Yoo Cha-Young , Kim Sung-Tae , Moon Joo-Tae
Published: October 2002

Rugged metal electrode (RME) was suggested and evaluated as a bottom electrode of high-density memory capacitors. Rugged ruthenium films (RME-Ru) were successfully fabricated through volume shrinking of ruthenium oxide films under reduction ambient (RuO
x
+H2=Ru+H2O). The effective surface area of RME-Ru films was significantly enlarged due to the formation of wrinkle on its surface, which resulted in low SiO2 equivalent thickness (Tox) as low as ∼ 6 Å with Ru/TaO
x
(110 Å)/RME-Ru capacitor. It is believed that RME technique will be very useful to realize and extend MIM (Metal-Insulator-Metal) capacitor era in the mass production of high density memory devices.
Field Electron Emission from Silicon Nanoprotrusions
Authors: Sawada Kazuaki , Tabe Michiharu , Ishikawa Yasuhiko , Iwatsuki Makoto , Ishida Makoto
Published: October 2002

Nanometer-scale silicon field emitters with the highest packing density were fabricated successfully using a self-organized selective oxidation technique. The diameter at the bottom of each nano-emitter was 20–30 nm, its height was 3–5 nm, and the radius of the apex of the protrusion was speculated to be 3–10 nm. The density was about 3–5×1011 tips/cm2, which is the highest value reported in the literature. Emission characteristics were measured by a diode structure without gate electrodes for simplicity. It was found that the field emission current was detected at a much lower anode voltage than the conventional cone-shaped Si emitters and the emission current depends on the microscopic shape controlled by oxidation conditions.
Measurement of Ultrashort-Pulse Cross-Polarization Scattering in a Tandem Mirror
Authors: Kogi Yuichiro , Mase Atsushi , Hojo Hitoshi , Itakura Akiyosi , Ichimura Makoto , Yatsu Kiyoshi
Published: October 2002

Cross-polarization scattering (CPS) diagnostics using ultrashort pulse microwaves is applied to the GAMMA 10 tandem mirror for the measurement of internal magnetic fluctuations. The CPS process uses the mode conversion effect of electromagnetic waves by means of magnetic fluctuations in a plasma. The mode contamination of antennas and multiple reflections from the vacuum vessel make the CPS measurement difficult since they easily mask the CPS signal. By using polarizers and performing time-of-flight measurement on the ultrashort pulse, the spurious electromagnetic waves are eliminated and the identification of the CPS process is successful.
Integrated Ultramicroelectrode: A Probe to Redox Reaction in Highly Resistive Medium
Authors: Umeda Minoru , Mohamedi Mohamed , Uchida Isamu
Published: October 2002

A novel integrated ultramicroelectrode (IUME) comprising a working, a counter and a reference electrodes built in a 0.5 mm-diameter of a capillary tip has been developed to measure electrochemical reactions in high-resistive and dilute media. By employing thus assembled IUME and cyclic voltammetry, we have succeeded to measure a redox reaction of ferrocenylmethyl trimethylammonium cation in aqueous solution without a supporting electrolyte, while a classical three-electrodes system failed to do so.
The Growth of Crystallinity in Undoped SiO:H Films at Low RF-Power Density and Substrate Temperature
Authors: Sarker Arindam , Bandyopadhyay Ashok K. , Barua Asok K.
Published: October 2002

Microcrystalline SiO:H films have been prepared by the usual RF plasma enhanced chemical vapor deposition (PECVD) method (13.56 MHz) at low rf-power density and substrate temperature which are essential for the fabrication of a-Si solar cell. The transition from amorphous to microcrystalline structure of SiO:H film has been shown to depend sensitively on hydrogen dilution and rf-power density. In the amorphous state, concentration of CO2 in the source gas mixture plays crucial role in determining optical gap whereas hydrogen dilution and rf-power density play important role in determining the characteristics of the microcrystalline SiO:H films.
Solution Electrochemiluminescent Cell Using Tris(phenylpyridine) Iridium
Authors: Nishimura Kazuki , Hamada Yuji , Tsujioka Tsuyoshi , Shibata Kenichi , Fuyuki Takashi
Published: October 2002

A solution electrochemiluminescent (SECL) cell is an emitting device that employs one type of emitting solution. In this study, tris(2-phenylpyridine) iridium [Ir(ppy)3], a well-known emitting material in organic electroluminescent cells, was used in a SECL cell. The cell had a simple structure of transparent electrode/emitting solution/transparent electrode. The solution consisted of benzonitrile used as the solvent, and Ir(ppy)3 used as the emitting material. When voltage was applied to this SECL cell, green emission was produced with a peak wavelength of 530 nm, which originated from Ir(ppy)3. This SECL cell showed a maximum luminance of 3 cd/m2 and a luminous efficiency of 0.014 cd/A. The features of the SECL cell are a simple cell structure and a transparent emitting area. SECL cells are expected to be used in unique displays with a see-through function for automobiles, windows, information displays, and so forth.
HF and Hydrazine Monohydrate Solution Treatment for Suppressing Oxidation of ZrN Film Surface
Authors: Sadayoshi Horii Sadayoshi Horii , Takeo Toda Takeo Toda , Susumu Horita Susumu Horita
Published: October 2002

Because the surface of a ZrN film was easily oxidized even immediately after the deposition, we did not obtain heteroepitaxial Ir film on the epitaxial ZrN film. In order to remove the oxidized layer from the ZrN film and suppress the oxidation, we propose a novel wet chemical treatment using HF and hydrazine (N2H4) monohydrate solution before the Ir film deposition. From the treated ZrN film surface, the X-ray photoelectron spectroscopy (XPS) spectrum showed the decrease of the oxide signal of the Zr3d spectrum. Moreover, on the treated epitaxial (100)ZrN film on the (100)Si substrate, we obtained the (100) epitaxial Ir film.
1/f Resistance Fluctuation of a Carbon Fiber
Authors: Akabane Hideo , Hiramatsu Junichi , Sato Miho , Agu Masahiro
Published: October 2002

1/f resistance fluctuations of carbon fiber are measured under the condition that tension of the carbon fiber is changed. The deformation of the fiber extends from an elastic region to a plastic one. It is found that the intensity of 1/f resistance fluctuations increases significantly as the applied tension increases, while the change of the mean value of the resistance is very small. The increase of the 1/f intensity is considered to originate from the change of the nonlinear potential caused by the applied tension.
Denying the digital divide
Authors: Korman Ken
Published: October 2002

As we go to press, the Bush administration has just issued its $2.13 trillion budget proposal for fiscal 2003. The news is not good for America's technologically disadvantaged.
The Origin of Binary Stars
Authors: Tohline Joel E.
Published: October 2002

▪ Abstract  Although we have a general understanding of the manner in which individual stars form, our understanding of how binary stars form is far from complete. This is in large part due to the fact that the star formation process happens very quickly and in regions of the Galaxy that are difficult to study observationally. We review the theoretical models that have been developed in an effort to explain how binaries form. Several proposed mechanisms appear to be quite promising, but none is completely satisfactory.
The New Galaxy: Signatures of Its Formation
Authors: Freeman Ken , Bland-Hawthorn Joss
Published: October 2002

▪ Abstract  The formation and evolution of galaxies is one of the great outstanding problems of astrophysics. Within the broad context of hierachical structure formation, we have only a crude picture of how galaxies like our own came into existence. A detailed physical picture where individual stellar populations can be associated with (tagged to) elements of the protocloud is far beyond our current understanding. Important clues have begun to emerge from both the Galaxy (near-field cosmology) and the high redshift universe (far-field cosmology). Here we focus on the fossil evidence provided by the Galaxy. Detailed studies of the Galaxy lie at the core of understanding the complex processes involved in baryon dissipation. This is a necessary first step toward achieving a successful theory of galaxy formation.
HOST-SELECTIVE TOXINS AND AVIRULENCE DETERMINANTS: What's in a Name?
Authors: Wolpert Thomas J. , Dunkle Larry D. , Ciuffetti Lynda M.
Published: October 2002

▪ Abstract  Host-selective toxins, a group of structurally complex and chemically diverse metabolites produced by plant pathogenic strains of certain fungal species, function as essential determinants of pathogenicity or virulence. Investigations into the molecular and biochemical responses to these disease determinants reveal responses typically associated with host defense and incompatibility induced by avirulence determinants. The characteristic responses that unify these disparate disease phenotypes are numerous, yet the evidence implicating a causal relationship of these responses, whether induced by host-selective toxins or avirulence factors, in determining the consequences of the host-pathogen interaction is equivocal. This review summarizes some examples of the action of host-selective toxins to illustrate the similarity in responses with those to avirulence determinants.
EVOLUTIONARYECOLOGY OFPLANTDISEASES INNATURALECOSYSTEMS
Authors: Gilbert Gregory S.
Published: October 2002

▪ Abstract  Plant pathogens cause mortality and reduce fecundity of individual plants, drive host population dynamics, and affect the structure and composition of natural plant communities. Pathogens are responsible for both numerical changes in host populations and evolutionary changes through selection for resistant genotypes. Linking such ecological and evolutionary dynamics has been the focus of a growing body of literature on the effects of plant diseases in natural ecosystems. A guiding principle is the importance of understanding the spatial and temporal scales at which plants and pathogens interact. This review summarizes the effects of diseases on populations of wild plants, focusing in particular on the mediation of plant competition and succession, the maintenance of plant species diversity, as well as the process of rapid evolutionary changes in host-pathogen symbioses.
MICROBIALPOPULATIONSRESPONSIBLE FORSPECIFICSOILSUPPRESSIVENESS TOPLANTPATHOGENS
Authors: Weller David M. , Raaijmakers Jos M. , Gardener Brian B. McSpadden , Thomashow Linda S.
Published: October 2002

▪ Abstract  Agricultural soils suppressive to soilborne plant pathogens occur worldwide, and for several of these soils the biological basis of suppressiveness has been described. Two classical types of suppressiveness are known. General suppression owes its activity to the total microbial biomass in soil and is not transferable between soils. Specific suppression owes its activity to the effects of individual or select groups of microorganisms and is transferable. The microbial basis of specific suppression to four diseases, Fusarium wilts, potato scab, apple replant disease, and take-all, is discussed. One of the best-described examples occurs in take-all decline soils. In Washington State, take-all decline results from the buildup of fluorescent Pseudomonas spp. that produce the antifungal metabolite 2,4-diacetylphloroglucinol. Producers of this metabolite may have a broader role in disease-suppressive soils worldwide. By coupling molecular technologies with traditional approaches used in plant pathology and microbiology, it is possible to dissect the microbial composition and complex interactions in suppressive soils.
PHYTOCHEMICALBASEDSTRATEGIES FORNEMATODECONTROL
Authors: Chitwood David J.
Published: October 2002

▪ Abstract  This review examines the discovery of naturally occurring phytochemicals antagonistic toward plant-parasitic and other nematodes. Higher plants have yielded a broad spectrum of active compounds, including polythienyls, isothiocyanates, glucosinolates, cyanogenic glycosides, polyacetylenes, alkaloids, lipids, terpenoids, sesquiterpenoids, diterpenoids, quassinoids, steroids, triterpenoids, simple and complex phenolics, and several other classes. Many other antinematodal compounds have been isolated from biocontrol and other fungi. Natural products active against mammalian parasites can serve as useful sources of compounds for examination of activity against plant parasites. The agricultural utilization of phytochemicals, although currently uneconomic in many situations, offers tremendous potential.
Development of Supported Bifunctional Electrocatalysts for Unitized Regenerative Fuel Cells
Authors: Chen Guoying , Bare Simon R. , Mallouk Thomas E.
Published: October 2002

Mixed metal catalysts containing Pt, Ir, Ru, Os, and Rh were synthesized on three different conductive oxide supports, Ebonex, which is a mixture ofTi4O7and other phases, phase-pure microcrystallineTi4O7,andTi0.9Nb0.1O2,a doped rutile compound. Ebonex-supported catalysts were prepared as arrays and screened combinatorially for activity and stability as bifunctional oxygen reduction/water oxidation catalysts. The highest activity and stability was found in the Pt-Ru-Ir ternary region at compositions nearPt4Ru4Ir1.X-ray near edge absorption spectra indicated a significant electronic interaction between the catalyst and the support, and a substantial increase in catalyst utilization was observed, even though the support surface areas were relatively low. Both Ebonex andTi4O7have short-lived electrochemical stability under conditions of oxygen evolution at+1.6Vvs.RHE in 0.5 MH2SO4.Current at these supported catalysts gradually decreases, and the decrease is attributed to loss of electronic conductivity. Ebonex andTi4O7are also thermally oxidized in air at temperatures above 400°C. In contrast,Ti0.9Nb0.1O2,which has a nondefective oxygen lattice, is quite resistant to electrochemical and thermal oxidation. Conditioning ofTi0.9Nb0.1O2-supportedPt4Ru4Ir1at positive potentials had little effect on the activity of the catalyst. © 2002 The Electrochemical Society. All rights reserved.
Vascular Inflammation and the Renin-Angiotensin System
Authors: Brasier Allan R. , Recinos Adrian , Eledrisi Mohsen S.
Published: October 2002

It is now well established that vascular inflammation is an independent risk factor for the development of atherosclerosis. In otherwise healthy patients, chronic elevations of circulating interleukin-6 or its biomarkers are predictors for increased risk in the development and progression of ischemic heart disease. Although multifactorial in etiology, vascular inflammation produces atherosclerosis by the continuous recruitment of circulating monocytes into the vessel wall and by contributing to an oxidant-rich inflammatory milieu that induces phenotypic changes in resident (noninflammatory) cells. In addition, the renin-angiotensin system (RAS) has important modulatory activities in the atherogenic process. Recent work has shown that angiotensin II (Ang II) has significant proinflammatory actions in the vascular wall, inducing the production of reactive oxygen species, inflammatory cytokines, and adhesion molecules. These latter effects on gene expression are mediated, at least in part, through the cytoplasmic nuclear factor-κB transcription factor. Through these actions, Ang II augments vascular inflammation, induces endothelial dysfunction, and, in so doing, enhances the atherogenic process. Our recent studies have defined a molecular mechanism for a biological positive-feedback loop that explains how vascular inflammation can be self-sustaining through upregulation of the vessel wall Ang II tone. Ang II produced locally by the inflamed vessel induces the synthesis and secretion of interleukin-6, a cytokine that induces synthesis of angiotensinogen in the liver through a janus kinase (JAK)/signal transducer and activator of transcription (STAT)-3 pathway. Enhanced angiotensinogen production, in turn, supplies more substrate to the activated vascular RAS, where locally produced Ang II synergizes with oxidized lipid to perpetuate atherosclerotic vascular inflammation. These observations suggest that one mechanism by which RAS antagonists prevent atherosclerosis is by reducing vascular inflammation. Moreover, antagonizing the vascular nuclear factor-κB and/or hepatic JAK/STAT pathways may modulate the atherosclerotic process.
Beneficial Effects of Combined Blockade of ACE and AT
1
Receptor on Intimal Hyperplasia in Balloon-Injured Rat Artery
Authors: Kim Shokei , Izumi Yasukatsu , Izumiya Yasuhiro , Zhan Yumei , Taniguchi Masaru , Iwao Hiroshi
Published: October 2002

Objective—

The present study was undertaken to elucidate the effect of the ACE inhibitor and the angiotensin II type 1 (AT
1
) receptor antagonist in combination on neointimal hyperplasia after balloon injury.

Methods and Results—

Temocapril (an ACE inhibitor), CS-866 (an AT
1
receptor antagonist), or their combination was given orally to rats, and their effects were compared on vascular hyperplasia induced by balloon injury. The maximal preventive effect of temocapril and CS-866 alone on neointimal thickening after balloon injury was obtained at a dose of 20 and 10 mg/kg per day, respectively. However, compared with either agent alone, combined temocapril and CS-866 (20 and 10 mg/kg per day, respectively) prevented intimal thickening to a larger extent. Furthermore, compared with either agent alone, combined temocapril and CS-866 prevented vascular smooth muscle cell proliferation in the intima more potently. The increase in platelet-derived growth factor receptor tyrosyl phosphorylation was reduced more potently by the combination of both agents compared with either agent alone. The nonpeptide bradykinin B
2
receptor antagonist or the NO synthase inhibitor reduced the prevention of intimal thickening by combined temocapril and CS-866.

Conclusions—

Compared with either agent alone, the combination of an ACE inhibitor and an AT
1
receptor antagonist is more effective in the prevention of vascular hyperplasia due to bradykinin or NO.
Vitamin C and E Intake Is Associated With Increased Paraoxonase Activity
Authors: Jarvik Gail P. , Tsai Nancey Trevanian , McKinstry Laura A. , Wani Roohi , Brophy Victoria H. , Richter Rebecca J. , Schellenberg Gerard D. , Heagerty Patrick J. , Hatsukami Thomas S. , Furlong Clement E.
Published: October 2002

Objective—

Paraoxonase (PON1), an esterase physically associated with high density lipoprotein, has been shown to inhibit atherogenic low density lipoprotein and high density lipoprotein oxidation. PON1 activity appears to be primarily under genetic control with some environmental modification and is a predictor of vascular disease. Vitamins C and E, dietary antioxidants, scavenge free-oxygen radical products that may depress PON1 activity. Therefore, we evaluated the relationship between dietary vitamin C and E intake and PON1 activity.

Methods and Results—

The vitamin C and E intakes of male white subjects (n=189) were estimated by using a standardized food frequency survey. With covariates, vitamin C or E intakes were found to be significant positive predictors of PON1 activity for the hydrolysis of paraoxon and diazoxon with the use of linear regression. Smoking and use of statins were independent predictors of PON1 activity.

Conclusions—

PON1 activity, which is primarily genotype dependent, varies with antioxidant vitamins, cigarette smoking, and statin drug use. Because PON1 activity is a better predictor of vascular disease than is the currently described genetic variation in PON1, further studies of the environmental influences on PON1 activity and additional PON1 genetic variants are warranted.
Epinephrine in the Heart
Authors: Lameris Thomas W. , de Zeeuw Sandra , Duncker Dirk J. , Tietge Wouter , Alberts Gooitzen , Boomsma Frans , Verdouw Pieter D. , van den Meiracker Anton H.
Published: October 2002

Background—

Several studies have suggested that epinephrine augments the release of norepinephrine from sympathetic nerve terminals through stimulation of presynaptic receptors, but evidence pertaining to this mechanism in the heart is scarce and conflicting. Using the microdialysis technique in the porcine heart, we investigated whether epinephrine, taken up by and released from cardiac sympathetic nerves, can increase norepinephrine concentrations in myocardial interstitial fluid (NE
MIF
) under basal conditions and during sympathetic activation.

Methods and Results—

During intracoronary epinephrine infusion of 10, 50, and 100 ng/kg per minute under basal conditions, large increments in interstitial (from 0.31±0.05 up to 140±30 nmol/L) and coronary venous (from 0.16±0.08 up to 228±39 nmol/L) epinephrine concentrations were found, but NE
MIF
did not change. Left stellate ganglion stimulation increased NE
MIF
from 3.4±0.5 to 8.2±1.5 nmol/L, but again, this increase was not enhanced by concomitant intracoronary epinephrine infusion. Intracoronary infusion of tyramine resulted in a negligible increase in epinephrine concentration in myocardial interstitial fluid (EPI
MIF
), whereas 30 minutes after infusion of epinephrine an increase of 9.5 nmol/L in EPI
MIF
was observed, indicating that epinephrine is taken up by and released from cardiac sympathetic neurons. Although 68% to 78% of infused epinephrine was extracted over the heart, the ratio of interstitial to arterial epinephrine concentrations was only ≈20%, increasing to 29% with neuronal reuptake inhibition.

Conclusions—

Our findings demonstrate epinephrine release from cardiac sympathetic neurons, but they do not provide evidence that epinephrine augments cardiac sympathoneural norepinephrine release under basal conditions or during sympathetic activation.
Cost-Effectiveness of Gamma Radiation for Treatment of In-Stent Restenosis
Authors: Cohen David J. , Cosgrove Roberta S. , Berezin Ronna H. , Teirstein Paul S. , Leon Martin B. , Kuntz Richard E.
Published: October 2002

Background

—

Recently, several randomized trials have demonstrated that intracoronary brachytherapy can reduce the rates of both angiographic and clinical restenosis in patients undergoing percutaneous coronary intervention (PCI) for in-stent restenosis. Whether this practice is cost-effective is unknown.

Methods and Results

—

Between December 1997 and July 1998, 252 patients with in-stent restenosis were randomized to receive brachytherapy or placebo after successful PCI as part of the Gamma-1 trial. We collected detailed resource utilization and cost data for each patient’s initial hospitalization and for 1 year after randomization. Compared with conventional treatment, intracoronary brachytherapy increased procedure duration, physician services, and equipment costs. As a result, initial costs were increased by nearly $4100 per patient ($15 724 versus $11 675,
P
<0.001). Over the 1-year follow-up period, brachytherapy reduced the need for repeat revascularization by 21% and reduced the need for bypass surgery by 44%. Although follow-up medical care costs were $2200/patient lower with brachytherapy, total costs remained higher at 1 year ($28 543 versus $26 737,
P
=0.46). In a sensitivity analysis that incorporated recent technical modifications and the use of prolonged antiplatelet therapy to prevent late thrombotic occlusion, follow-up cost savings increased to $3600/patient, and 1-year costs were slightly lower with brachytherapy ($26 352 versus $26 729,
P
=0.87). Subgroup analysis demonstrated significant cost savings in patients with diabetes and patients who did not undergo repeat stenting.

Conclusions

—

As performed in the Gamma-1 trial, coronary brachytherapy for in-stent restenosis improved clinical outcomes but increased 1-year costs compared with standard therapy. If late thrombosis can be eliminated, however, this technology has the potential to reduce overall medical care costs.
Role of Endogenous Adenosine as a Modulator of Syncope Induced During Tilt Testing
Authors: Saadjian Alain Y. , Lévy Samuel , Franceschi Fréderic , Zouher Ibrahim , Paganelli Franck , Guieu Régis P.
Published: October 2002

Background

—

Previous reports that used head-up tilt testing and adenosine administration have suggested that adenosine may be an important endogenous mediator that may trigger a vasovagal response in susceptible patients. However, little is known regarding endogenous adenosine plasma levels (APLs) during vasovagal syncope provoked by tilt testing. The aim of this study was to determine whether APLs differ in patients with a positive head-up tilt test compared with those with a negative test and whether APLs are modified during tilt-induced vasovagal syncope.

Methods and Results

—

APLs (mean±SEM) were measured during head-up tilt test in 26 patients who presented with unexplained syncope. In the 15 patients with a negative test, APLs were 0.39±0.03 μmol/L at baseline, 0.22±0.03 μmol/L immediately after tilting, and 0.44±0.03 μmol/L after 45 minutes. APLs were significantly higher in the 11 patients with a positive test (2.66±0.67 μmol/L at baseline and 3.22±0.85 μmol/L immediately after tilting) than in those with a negative test. During tilt testing–induced syncope, APLs increased to reach 4.03±0.66 μmol/L (ie, a 52% increase compared with baseline levels;
P
<0.02). Furthermore, we observed that the higher the APL during syncope, the shorter the time to appearance of symptoms.

Conclusions

—

This study showed that APLs were higher in patients with a positive tilt test than in patients with a negative test and that they increased during tilt testing–induced syncope. These observations suggest that adenosine release may be involved in the triggering mechanism of syncope induced during tilt testing.
Bionic Technology Revitalizes Native Baroreflex Function in Rats With Baroreflex Failure
Authors: Sato Takayuki , Kawada Toru , Sugimachi Masaru , Sunagawa Kenji
Published: October 2002

Background

—

We developed a bionic technology for the treatment of baroreflex failure and tested its efficacy in restoration of arterial pressure against head-up tilt (HUT) in rats with baroreflex failure.

Methods and Results

—

The bionic baroreflex system (BBS) was a negative feedback system controlled by a computer, the artificial vasomotor center. It sensed systemic arterial pressure (SAP) through a micromanometer placed in the aortic arch and automatically computed the frequency of a pulse train to stimulate sympathetic efferent nerves. We selected the celiac ganglion as the sympathetic vasomotor interface. To make this system bionic, the operational rule of the artificial vasomotor center (H
BRP→STM
; BRP indicates baroreceptor pressure; STM, electrical stimulation) was actively matched to that of the native center. First, we identified the open-loop transfer functions of the native baroreflex control of SAP (H
Native
) and the response of SAP to electrical stimulation of the celiac ganglion (H
STM→SAP
). We computed H
BRP→STM
from H
Native
/H
STM→SAP
and transplanted the operational rule into the computer. In 10 rats with baroreflex failure, we evaluated the performance of the BBS during rapid hypotension induced by HUT. Abrupt HUT dropped SAP by 34±6 mm Hg in 2 seconds and by 52±5 mm Hg in 10 seconds. During real-time execution of the BBS, on the other hand, the fall in SAP was 21±5 mm Hg at 2 seconds and 15±6 mm Hg at 10 seconds after HUT. These arterial responses controlled by the BBS were indistinguishable from those by the native baroreflex.

Conclusions

—

We concluded that the BBS revitalized the native baroreflex function in rats with baroreflex failure.
Prediction of Long-Term Prognosis in 12 169 Men Referred for Cardiac Rehabilitation
Authors: Kavanagh Terence , Mertens Donald J. , Hamm Larry F. , Beyene Joseph , Kennedy Johanna , Corey Paul , Shephard Roy J.
Published: October 2002

Background

—

Predicting the risk of cardiac and all-cause death in patients with established coronary heart disease is important in counseling the individual and designing risk-stratified rehabilitation and secondary prevention programs. Cox proportional hazards and Kaplan-Meier survival curves were thus completed on initial assessment data obtained from patients referred to an outpatient cardiac rehabilitation center.

Methods and Results

—

A single-center prospective observational design took peak cardiorespiratory exercise test data for 12 169 male rehabilitation candidates aged 55.0±9.6 years (7096 myocardial infarctions [MIs], 3077 coronary artery bypass grafts [CABGs], and 1996 documented cases of ischemic heart disease [IHD]). A follow-up of 4 to 29 years (median, 7.9) yielded 107 698 man-years of experience. Entry data were tested for associations with time to cardiac and all-cause death. We recorded 1336 cardiac deaths (953 MI, 225 CABG, and 158 IHD) and 2352 all-cause deaths. A powerful predictor of cardiac and all-cause mortality was measured peak oxygen intake (V̇
o
2peak
). For the overall sample, values of <15, 15 to 22, and >22 mL/kg per minute yielded respective multivariate adjusted hazard ratios of 1.00, 0.62, and 0.39 for cardiac and 1.00, 0.66, and 0.45 for all-cause deaths. For the separate diagnostic categories, apart from V̇
o
2peak
, the only other significant predictors of cardiac death common to all 3 were smoking and digoxin, and for all-cause death, age, smoking, digoxin, and diabetes.

Conclusions

—

Exercise capacity, as determined by direct measurement of V̇
o
2peak
, exerts a major long-term influence on prognosis in men after MI, CABG, or IHD and can play a valuable role in risk stratification and counseling.
Prognostic Value of Coronary Vascular Endothelial Dysfunction
Authors: Halcox Julian P.J. , Schenke William H. , Zalos Gloria , Mincemoyer Rita , Prasad Abhiram , Waclawiw Myron A. , Nour Khaled R.A. , Quyyumi Arshed A.
Published: October 2002

Background

—

Whether patients at increased risk can be identified from a relatively low-risk population by coronary vascular function testing remains unknown. We investigated the relationship between coronary endothelial function and the occurrence of acute unpredictable cardiovascular events (cardiovascular death, myocardial infarction, stroke, and unstable angina) in patients with and without coronary atherosclerosis (CAD).

Methods and Results

—

We measured the change in coronary vascular resistance (ΔCVR) and epicardial diameter with intracoronary acetylcholine (ACh, 15 μg/min) to test endothelium-dependent function and sodium nitroprusside (20 μg/min) and adenosine (2.2 mg/min) to test endothelium-independent vascular function in 308 patients undergoing cardiac catheterization (132 with and 176 without CAD). Patients underwent clinical follow-up for a mean of 46±3 months. Acute vascular events occurred in 35 patients. After multivariate analysis that included CAD and conventional risk factors for atherosclerosis, ΔCVR with ACh (
P
=0.02) and epicardial constriction with ACh (
P
=0.003), together with increasing age, CAD, and body mass index, were independent predictors of adverse events. Thus, patients in the tertile with the best microvascular responses with ACh and those with epicardial dilation with ACh had improved survival by Kaplan-Meier analyses in the total population, as did those in the subset without CAD. Similar improvement in survival was also observed when all adverse events, including revascularization, were considered. Endothelium-independent responses were not predictive of outcome.

Conclusions

—

Epicardial and microvascular coronary endothelial dysfunction independently predict acute cardiovascular events in patients with and without CAD, providing both functional and prognostic information that complements angiographic and risk factor assessment.
Microvascular Structural Correlates of Myocardial Contrast Echocardiography in Patients With Coronary Artery Disease and Left Ventricular Dysfunction
Authors: Shimoni Sarah , Frangogiannis Nikolaos G. , Aggeli Constadina J. , Shan Kesavan , Quinones Miguel A. , Espada Rafael , Letsou George V. , Lawrie Gerald M. , Winters William L. , Reardon Michael J. , Zoghbi William A.
Published: October 2002

Background—

Myocardial contrast echocardiography (MCE) has been used to evaluate myocardial viability. There are no data, however, on the pathological determinants of myocardial perfusion by MCE in humans and the implications of such determinants.

Methods and Results—

MCE was performed in 20 patients with coronary artery disease and ventricular dysfunction within 24 hours before myocardial biopsy at surgery using a continuous Optison infusion (12 to 16 cc/h), with intermittent pulse inversion harmonics and incremental triggering. Peak myocardial contrast intensity (MCI) and the rate of increase in MCI (β) were quantitated. Thirty-six transmural myocardial biopsies (2 per patient) were obtained by transesophageal echocardiography. Total microvascular (<100 μm) density, capillary density and area, arteriolar and venular density, and percent collagen content were quantitated with immunohistochemistry. Peak MCI correlated with microvascular density (
r
=0.59,
P
<0.001) and capillary area (
r
=0.64,
P
<0.001) and inversely correlated with percent collagen content (
r
=−0.45,
P
=<0.01). The best relation was observed when the ratio of peak MCI in the 2 biopsied segments in each patient was compared with the ratio of microvascular density and capillary area (
r
=0.84 and 0.87, respectively;
P
<0.001). A significant overlap in microvascular density was seen between segments with and without recovery of function. The new MCE indices of blood velocity (β) and flow (peak MCI×β) better identified recovery of function compared with microvascular density and the sole use of peak MCI.

Conclusions—

Microvascular integrity is a significant determinant of maximal MCI in humans. MCE indices of blood velocity and flow are important parameters that predict recovery of function after revascularization.
Intramural Virtual Electrodes During Defibrillation Shocks in Left Ventricular Wall Assessed by Optical Mapping of Membrane Potential
Authors: Fast Vladimir G. , Sharifov Oleg F. , Cheek Eric R. , Newton Jonathan C. , Ideker Raymond E.
Published: October 2002

Background—

It is believed that defibrillation is due to shock-induced changes of transmembrane potential (ΔV
m
) in the bulk of ventricular myocardium (so-called virtual electrodes), but experimental proof of this hypothesis is absent. Here, intramural shock-induced ΔV
m
were measured for the first time in isolated preparations of left ventricle (LV) by an optical mapping technique.

Methods and Results—

LV preparations were excised from porcine hearts (n=9) and perfused through a coronary artery. Rectangular shocks (duration 10 ms, field strength E ≈2 to 50 V/cm) were applied across the wall during the action potential plateau by 2 large electrodes. Shock-induced ΔV
m
were measured on the transmural wall surface with a 16×16 photodiode array (resolution 1.2 mm/diode). Whereas weak shocks (E≈2 V/cm) induced negligible ΔV
m
in the wall middle, stronger shocks produced intramural ΔV
m
of 2 types. (1) Shocks with E>4 V/cm produced both positive and negative intramural ΔV
m
that changed their sign on changing shock polarity, possibly reflecting large-scale nonuniformities in the tissue structure; the ΔV
m
patterns were asymmetrical, with ΔV
−
m
>ΔV
+
m
. (2) Shocks with E>34 V/cm produced predominantly negative ΔV
m
across the whole transmural surface, independent of the shock polarity. These relatively uniform polarizations could be a result of microscopic discontinuities in tissue structure.

Conclusions—

Strong defibrillation shocks induce ΔV
m
in the intramural layers of LV. During action potential plateau, intramural ΔV
m
are typically asymmetrical (ΔV
−
m
>ΔV
+
m
) and become globally negative during very strong shocks.
Stent-Based Approach for Ventricle–to–Coronary Artery Bypass
Authors: Boekstegers Peter , Raake Philip , Al Ghobainy Rasul , Horstkotte Jan , Hinkel Rabea , Sandner Torleif , Wichels Reinhard , Meisner Franz , Thein Eckehard , March Keith , Boehm Dieter , Reichenspurner Hermann
Published: October 2002

Background—

Ventricle-to–coronary artery bypass (VCAB) is an experimental revascularization procedure that provides predominantly systolic instead of diastolic blood flow to a coronary artery.

Methods and Results—

In a pig model, a stent-based procedure (VSTENT) was developed to create a VCAB. After thoracotomy, a covered VSTENT was implanted between the left ventricle and the left anterior descending coronary artery (LAD). Distal LAD flow, regional myocardial function, and intracoronary pressures were determined at different degrees of LAD stenosis and during complete LAD occlusion. During 3 hours of LAD occlusion, VSTENT preserved net forward flow at 70±6% and regional myocardial function at 71±8% of baseline. Preservation of net flow was influenced by the positioning of the VSTENT, with higher preservation also under conditions of increased oxygen demand if a “valve-like mechanism” was present during diastole. At a hemodynamically relevant level of LAD stenosis (>70%), systolic inflow was predominant after VSTENT implantation. Changes in mean diastolic intracoronary pressure that resulted from different degrees of LAD stenosis were linearly correlated to net flow after VSTENT implantation (
r
=0.88;
P
<0.001).

Conclusions—

VSTENT for ventricle-to–coronary artery bypass was feasible and preserved 70±6% of baseline flow during complete LAD occlusion. The degree of preservation was dependent on the position of the VSTENT creating a valve-like mechanism during diastole. Residual diastolic blood flow through a high-grade LAD stenosis influenced net flow favorably, because diastolic backflow decreased with increasing mean diastolic intracoronary pressure.
Prevalence of Significant Noncardiac Findings on Electron-Beam Computed Tomography Coronary Artery Calcium Screening Examinations
Authors: Horton Karen M. , Post Wendy S. , Blumenthal Roger S. , Fishman Elliot K.
Published: October 2002

Background—

Screening electron-beam computed tomography (EBCT) examinations for the detection and quantification of coronary artery calcification are being performed throughout the country. In addition to information about the heart, great vessels, and coronary arteries, these examinations include portions of the lungs, bony thorax, and upper abdomen. The purpose of this study was to determine the prevalence of significant noncardiac findings in a series of patients undergoing coronary artery calcification screening studies with EBCT scanning.

Methods and Results
—

Between January 1, 2001, and October 1, 2001, 1326 consecutive patients underwent coronary artery calcification screening with EBCT (3-mm-thick slices were obtained at 3-mm intervals). Two board-certified radiologists reviewed the examinations on a workstation using standard mediastinal windows, lung windows, and bone windows. Significant extracardiac abnormalities were noted. Of 1326 patients, 103 (7.8%) had significant extracardiac pathology requiring clinical or imaging follow-up. These included 53 patients with noncalcified lung nodules <1 cm, 12 patients with lung nodules ≥1 cm, 24 patients with infiltrates, 7 patients with indeterminate liver lesions, 2 patients with sclerotic bone lesions, 2 patients with breast abnormalities, 1 patient with polycystic liver disease, 1 patient with esophageal thickening, and 1 patient with ascites.

Conclusions
—

In this study, 7.8% of patients undergoing screening EBCT examinations for coronary artery calcification were found to have important extracardiac pathology requiring additional work-up. Therefore, it is essential that a radiologist review the entire examination.
Particulate Air Pollution and Risk of ST-Segment Depression During Repeated Submaximal Exercise Tests Among Subjects With Coronary Heart Disease
Authors: Pekkanen Juha , Peters Annette , Hoek Gerard , Tiittanen Pekka , Brunekreef Bert , de Hartog Jeroen , Heinrich Joachim , Ibald-Mulli Angela , Kreyling Wolfgang G. , Lanki Timo , Timonen Kirsi L. , Vanninen Esko
Published: October 2002

Background—

Daily variations in ambient particulate air pollution have been associated with cardiovascular mortality and morbidity. We therefore assessed the associations between levels of the 3 main modes of urban aerosol distribution and the occurrence of ST-segment depressions during repeated exercise tests.

Methods and Results—

Repeated biweekly submaximal exercise tests were performed during 6 months among adult subjects with stable coronary heart disease in Helsinki, Finland. Seventy-two exercise-induced ST-segment depressions >0.1 mV occurred during 342 exercise tests among 45 subjects. Simultaneously, particle mass <2.5 μm (PM2.5) and the number concentrations of ultrafine particles (particle diameter 10 to 100 nm [NC
0.01–0.1
]) and accumulation mode particles (100 to 1000 nm [NC
0.1–1
]) were monitored at a central site. Levels of particulate air pollution 2 days before the clinic visit were significantly associated with increased risk of ST-segment depression during exercise test. The association was most consistent for measures of particles reflecting accumulation mode particles (odds ratio 3.29; 95% CI, 1.57 to 6.92 for NC
0.1–1
and 2.84; 95% CI, 1.42 to 5.66 for PM2.5), but ultrafine particles also had an effect (odds ratio 3.14; 95% CI, 1.56 to 6.32), which was independent of PM2.5. Also, gaseous pollutants NO
2
and CO were associated with an increased risk for ST-segment depressions. No consistent association was observed for coarse particles. The associations tended to be stronger among subjects who did not use β-blockers.

Conclusions—

The present results suggest that the effect of particulate air pollution on cardiovascular morbidity is at least partly mediated through increased susceptibility to myocardial ischemia.
Endovascular Stent Grafting Versus Open Surgical Operation in Patients With Infrarenal Aortic Aneurysms
Authors: Teufelsbauer Harald , Prusa Alexander M. , Wolff Klaus , Polterauer Peter , Nanobashvili Josif , Prager Manfred , Hölzenbein Thomas , Thurnher Siegfried , Lammer Johannes , Schemper Michael , Kretschmer Georg , Huk Ihor
Published: October 2002

Background—

Although transfemoral endovascular aneurysm management (TEAM) of infrarenal abdominal aortic aneurysms (AAA) is widely performed, open graft replacement is still considered the standard of care. The aim of this study was to investigate whether clear indications for TEAM can be established in patients with significant comorbidities without investigating differences in relative procedure efficacy or durability.

Methods and Results—

A propensity score–based analysis of 454 consecutive patients treated electively for AAA from January 1995 through December 2000 was performed. Of those 454 patients, 248 received open surgery and 206 received TEAM. In-hospital mortality rates (MRs) were compared. After adjusting for propensity scores, a Cox proportional hazard model (COX) was employed to test the influence of the respective treatment on postoperative 900-day survival estimates (SEs). Several potential preoperative risk factors were used as covariates. The MR of all patients was 3.7%. Explorative analysis demonstrated that patients treated by TEAM presented with significantly more risk factors. In American Society of Anesthesiologists class IV patients, a significant difference in MR was detected (4.7% for TEAM versus 19.2% for open surgery;
P
<0.02). After adjusting for the propensity to receive TEAM or open surgery, a regression analysis of survival based on COX revealed predictive influences of impaired kidney (
P
<0.047) or pulmonary function (
P
<0.001), increased age (
P
<0.05), and selection of treatment modality (
P
<0.002) on SE.

Conclusions—

TEAM represents a less invasive procedure for AAA therapy in patients with significant preoperative risk factors. Especially in geriatric patients with multiple morbidities, TEAM offers a method of therapy with acceptable MRs and SEs, making active treatment possible in otherwise incurable patients.