bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Chronic Treatment With the Inducible Nitric Oxide Synthase Inhibitor
N
-Iminoethyl-
l
-Lysine or With
l
-Arginine on Progression of Coronary and Aortic Atherosclerosis in Hypercholesterolemic Rabbits
Authors: Behr-Roussel Delphine , Rupin Alain , Simonet Serge , Bonhomme Edith , Coumailleau Sophie , Cordi Alex , Serkiz Bernard , Fabiani Jean-Noël , Verbeuren Tony J.
Published: June 2012

Background
—We examined the implications of iNOS in atherosclerosis progression using the selective inducible NO synthase (iNOS) inhibitor
N
-iminoethyl-
l
-lysine (L-NIL) in hypercholesterolemic rabbits.

Methods and Results
—Nine rabbits were fed a 0.3% cholesterol diet for 24 weeks (Baseline group); 25 animals were maintained on the diet and treated for 12 extra weeks with L-NIL (5 mg · kg
−
1
· d
−
1
, L-NIL group, n=8), vehicle (Saline group, n=9), or
l
-arginine (2.25%, L-Arg group, n=8). In abdominal aortas of Saline rabbits, the lesions (53.7±5.7%, Baseline) increased to 75.0±5.0% (
P
<0.05) but remained unaltered in the L-NIL group (63.4±6.6%). Similar results were obtained for the intima/media ratio in thoracic aortas. In coronary arteries, the intima/media ratio was comparable in Baseline (0.68±0.18) and Saline (0.96±0.19) rabbits but decreased to 0.34±0.19 (
P
<0.05) in L-NIL rabbits.
l
-Arginine had beneficial effects only in abdominal aortas. An increased thoracic aorta collagen content was found in Saline and L-Arg but not in L-NIL rabbits. In thoracic aortas of the Saline group, acetylcholine caused modest relaxations that slightly increased by
l
-arginine but not by L-NIL. Relaxations to nitroglycerin were ameliorated by L-NIL.

Conclusions
—This is the first study showing that chronic treatment with an iNOS inhibitor, L-NIL, limits progression of preexisting atherosclerosis in hypercholesterolemic rabbits. Increased intimal collagen accumulation may participate in iNOS-induced atherosclerosis progression.
Endothelial Dysfunction After Repeated
Chlamydia pneumoniae
Infection in Apolipoprotein E–Knockout Mice
Authors: Liuba Petru , Karnani Päivi , Pesonen Erkki , Paakkari Ilari , Forslid Anders , Johansson Leif , Persson Kenneth , Wadström Torkel , Laurini Ricardo
Published: June 2012

Background
—Arterial relaxation is largely regulated by endothelial nitric oxide (NO). Its diminished activity has been associated with incipient atherosclerosis. We investigated the endothelium-dependent relaxation of aorta in apolipoprotein E–knockout (apoE-KO) mice exposed to single or repeated
Chlamydia pneumoniae
inoculation.

Methods and Results
—Forty-eight apoE-KO mice, 8 weeks old, were inoculated intranasally with
C pneumoniae
(n=24) or saline (n=24) every 2 weeks over a 6-week period. Twenty mice (10 infected and 10 controls) were killed at 2 weeks and 6 weeks, respectively, after the first inoculation. The smooth muscle tone of aortic rings was measured in vitro at both time points. The norepinephrine-precontracted thoracic aortic rings were successively exposed to methacholine in the absence and presence of
N
G
-nitro-
l
-arginine methyl ester (L-NAME) and diclofenac. The methacholine-induced relaxation was attenuated in the infected mice at 6 weeks in both the absence and presence of L-NAME (
P
<0.05 and
P
<0.01, respectively). When administered together with L-NAME, diclofenac enhanced the relaxation of the L-NAME–pretreated aortas in infected mice at 2 weeks (
P
<0.05) but not in noninfected mice. The relaxation response from infected mice tended to differ in the same manner at 6 weeks (
P
<0.1). No intimal thickening was detected at either time point.

Conclusions
—
C pneumoniae
impairs arterial endothelial function, and the NO pathway is principally involved. Cyclooxygenase-dependent vasoconstricting products may also account for the infection-induced impaired relaxation. These findings further support the role of
C pneumoniae
infection in atherosclerosis development.
Visualization of Fibrous Cap Thickness and Rupture in Human Atherosclerotic Carotid Plaque In Vivo With High-Resolution Magnetic Resonance Imaging
Authors: Hatsukami Thomas S. , Ross Russell , Polissar Nayak L. , Yuan Chun
Published: June 2012

Background
—The results of studies of advanced lesions of atherosclerosis suggest that the thickness of the fibrous cap that overlies the necrotic core distinguishes the stable lesion from one that is at high risk for rupture and thromboembolic events. We have developed a high-resolution MRI technique that can identify the fine structure of the lesion, including the fibrous cap, in vivo. The aim of the present study was to determine the agreement between in vivo MRI and lesion architecture as seen on histology and gross tissue examination to identify fibrous cap thickness and rupture.

Methods and Results
—Twenty-two subjects who were scheduled for carotid endarterectomy underwent MRI with a 3-dimensional multiple overlapping thin slab angiography protocol. The appearance of the fibrous cap was categorized as (1) an intact, thick, (2) an intact, thin, or (3) a ruptured fibrous cap on MRI, gross, and histological sections. Thirty-six sites were available for comparison between MRI and histology. There was a high level of agreement between MRI and histological findings: 89% agreement, κ (95% CI)=0.83 (0.67 to 1.0), weighted κ=0.87. Spearman’s correlation coefficient was 0.88 (significant to the 0.01 level).

Conclusions
—These findings indicate that high-resolution MRI with a 3-dimensional multiple overlapping thin slab angiography protocol is capable of distinguishing intact, thick fibrous caps from intact thin and disrupted caps in atherosclerotic human carotid arteries in vivo. This noninvasive technique has the potential to permit studies that examine the relationship between fibrous cap changes and clinical outcome and to permit trials that evaluate therapy intended to “stabilize” the fibrous cap.
Postexercise Ischemia Is Associated With Increased Neuropeptide Y in Patients With Coronary Artery Disease
Authors: Gullestad Lars , Jørgensen Bjørn , Bjurø Thorvald , Pernow John , Lundberg Jan M. , Dota Corina-Dana , Hall Christian , Simonsen Svein , Åblad Bengt
Published: June 2012

Background
—Neurohormones may influence vascular tone both during and after exercise. Neuropeptide Y (NPY), which is costored and released with norepinephrine (NE) during sympathetic activity, is a potent vasoconstrictor with a relatively long half-life. We therefore examined its possible association with the ischemic response to exercise in patients with coronary artery disease.

Methods and Results
—Twenty-nine male patients with effort-induced angina pectoris underwent a symptom-limited exercise test. In addition to conventional ST-segment analysis, we examined ischemia on the basis of heart rate (HR)-adjusted ST-segment changes through calculation of the ST/HR slope during the final 4 minutes of exercise and of the ST/HR recovery loop after exercise. Blood samples were taken before, during, and after exercise for an analysis of several neurohormones. Mean ST-segment depression was −223±20.2 μV (
P
<0.0001) just before the termination of exercise, followed by a gradual normalization, but it remained significant after 10 minutes (−49±8.9 μV,
P
<0.0001). At the end of exercise, the ST/HR slope, which reflects myocardial ischemia, was −6.0±0.77 μV/HR. In most patients, ST-segment levels at a given HR were lower during recovery than during exercise, here referred to as ST “deficit.” Exercise increased the plasma levels of NPY, NE, epinephrine, and N-terminal proatrial natriuretic peptide, but big endothelin remained unchanged. Although NE and epinephrine peaked at maximal exercise, the highest levels of NPY and N-terminal proatrial natriuretic peptide were observed 4 minutes after exercise. The maximal increase in the NPY correlated significantly with ST-segment depression at 3 minutes after exercise (
r
=−0.61,
P
=0.0005), the ST deficit at the corresponding time point (
r
=−0.66,
P
=0.0001), and the duration of ST-segment depression after exercise (
r
=0.42,
P
=0.02). In contrast, no such correlations were found for NE.

Conclusions
—The present study has for the first time demonstrated a correlation between plasma NPY levels and the degree and duration of ST-segment depression after exercise in patients with coronary artery disease, which suggests that NPY may contribute to myocardial ischemia in these patients.
Elevation of Plasma High-Density Lipoprotein Concentration Reduces Interleukin-1–Induced Expression of E-Selectin in an In Vivo Model of Acute Inflammation
Authors: Cockerill Gillian W. , Huehns Tanya Y. , Weerasinghe Arjuna , Stocker Claire , Lerch Peter G. , Miller Norman E. , Haskard Dorian O.
Published: June 2012

Background
—Although there is strong evidence that plasma HDL levels correlate inversely with the incidence of coronary artery disease, the precise mechanism(s) for the protective effect of HDLs remains unclear. We recently showed that HDLs inhibit endothelial cell expression of cytokine-induced leukocyte adhesion molecules in vitro. Our study therefore sought to test the hypothesis that elevating the level of circulating HDLs would inhibit endothelial cell activation in vivo.

Methods and Results
—We used a porcine model of inflammation previously established in our laboratory, in which the level of vascular endothelial cell expression of E-selectin in interleukin (IL)-1α–induced skin lesions was measured by the uptake of a radiolabeled anti–E-selectin antibody (1.2B6). Porcine plasma HDL levels were elevated by use of a bolus injection of reconstituted discoidal HDL (recHDL). These particles resemble nascent HDL particles in shape and contain apolipoprotein A-I as the sole protein and soybean phosphatidylcholine as the sole phospholipid. We found that recHDLs inhibited the expression of IL-1α–induced E-selectin by porcine aortic endothelial cells in vitro, confirming that the inhibitory effect is conserved with synthetic HDLs and demonstrating that the phenomenon is not restricted to human endothelial cells. In vivo, elevating the circulating level of HDLs ≈2-fold led to significant inhibition of basal and IL-1α–induced E-selectin expression by porcine microvascular endothelial cells.

Conclusions
—These observations demonstrate the potential anti-inflammatory action of HDLs and provide support for the further investigation of the mechanisms underlying the inhibitory effects of HDLs on endothelial cell activation.
Hypertrophic Cardiomyopathy Caused by a Novel α-Tropomyosin Mutation (V95A) Is Associated With Mild Cardiac Phenotype, Abnormal Calcium Binding to Troponin, Abnormal Myosin Cycling, and Poor Prognosis
Authors: Karibe Akihiko , Tobacman Larry S. , Strand James , Butters Carol , Back Nick , Bachinski Linda L. , Arai Andrew E. , Ortiz Anne , Roberts Robert , Homsher Earl , Fananapazir Lameh
Published: June 2012

Background
—We report hypertrophic cardiomyopathy (HCM) in a Spanish-American family caused by a novel α-tropomyosin (
TPM1)
mutation and examine the pathogenesis of the clinical disease by characterizing functional defects in the purified mutant protein.

Methods and Results
—HCM was linked to the
TPM1
gene (logarithm of the odds [LOD] score 3.17). Sequencing and restriction digestion analysis demonstrated a
TPM1
mutation V95A that cosegregated with HCM. The mutation has been associated with 13 deaths in 26 affected members (11 sudden deaths and 2 related to heart failure), with a cumulative survival rate of 73±10% at the age of 40 years. Left ventricular wall thickness (mean 16±6 mm) and disease penetrance (53%) were similar to those for the β-myosin mutations L908V and G256E previously associated with a benign prognosis. Left ventricular hypertrophy was milder than with the β-myosin mutation R403Q, but the prognosis was similarly poor. With the use of recombinant tropomyosins, we identified several functional alterations at the protein level. The mutation caused a 40% to 50% increase in calcium affinity in regulated thin filament–myosin subfragment-1 (S1) MgATPase assays, a 20% decrease in MgATPase rates in the presence of saturating calcium, a 5% decrease in unloaded shortening velocity in in vitro motility assays, and no change in cooperative myosin S1 binding to regulated thin filaments.

Conclusions
—In contrast to other reported
TPM1
mutations, V95A-associated HCM exhibits unusual features of mild phenotype but poor prognosis. Both myosin cycling and calcium binding to troponin are abnormal in the presence of the mutant tropomyosin. The genetic diagnosis afforded by this mutation will be valuable in the management of HCM.
Effect of P-Wave Timing During Supraventricular Tachycardia on the Hemodynamic and Sympathetic Neural Response
Authors: Hamdan Mohamed H. , Zagrodzky Jason D. , Page Richard L. , Wasmund Stephen L. , Sheehan Clifford J. , Adamson Mathew M. , Joglar Jose A. , Smith Michael L.
Published: June 2012

Background
—Previous studies have shown the importance of the timing of atrial and ventricular systole on the hemodynamic response during supraventricular tachycardia (SVT). However, the reflex changes in autonomic tone during SVT remain poorly understood.

Methods and Results
—Eleven patients with permanent dual-chamber pacemakers were enrolled in the study. Arterial blood pressure (BP), central venous pressure (CVP), and peripheral muscle sympathetic nerve activity (SNA) were recorded during DDD pacing at a rate of 175 bpm (cycle length 343 ms) with an atrioventricular (AV) interval of 30, 200 and 110 ms, simulating tachycardia with near-simultaneous atrial and ventricular systole, short-RP tachycardia (RPPR). Each pacing run was performed for 3 minutes separated by a 5-minute recovery period. All patients demonstrated an abrupt fall in BP, an increase in CVP, and an increase in SNA regardless of the AV interval. The decreases in SBP, DBP, and MAP and the increase in CVP were significantly less during long-RP tachycardia (AV interval 110 ms) than during the other 2 pacing modes (
P
<0.05), and the increase in SNA in 7 of the 11 patients was significantly greater during closely coupled atrial and ventricular systole than during long-RP tachycardia (
P
<0.05).

Conclusions
—These data suggest that the superior maintenance of hemodynamic stability during long-RP tachycardia is accompanied by reduced sympathoexcitation, which is primarily mediated by the arterial baroreceptors, with a modest cardiopulmonary vasodepressor effect.
Effect of Testosterone on Plaque Development and Androgen Receptor Expression in the Arterial Vessel Wall
Authors: Hanke Hartmut , Lenz Christina , Hess Beate , Spindler Klaus-Dieter , Weidemann Wolfgang
Published: June 2012

Background
—Recent studies have suggested that testosterone has a protective effect in the arterial vascular system. However, little is known about the molecular aspects of the mechanism(s) involved in these processes. The aim of the present study was to investigate the effect of testosterone on neointimal plaque development and on the expression of the vascular androgen receptor.

Methods and Results
—Neointimal plaque formation was induced by endothelial denudation in the aortas of male New Zealand White rabbits. Aortic ring segments were cultured for 21 days after endothelial denudation. Testosterone was applied to the culture medium in different doses. Compared with the non–hormone-treated control group, a significant inhibition of neointimal plaque development (expressed as the intima/media ratio) was found at testosterone concentrations of 10 ng/mL (
P
=0.037) and 100 ng/mL (
P
=0.012; intima/media ratios: median of controls, 0.25; median of 10 ng/mL testosterone group, 0.15; median of 100 ng/mL testosterone group, 0.16). Associated with this inhibitory effect on plaque size was a 50% increase of the amount of androgen receptor mRNA in the arterial segments treated with testosterone.

Conclusion
—The beneficial effects of testosterone on postinjury plaque development underlines, at least in males, the important role of androgens in the vascular system. As our data suggest, the vascular androgen receptor is probably involved in these processes. Further studies are required to characterize the androgen receptor–dependent pathways in the vascular system.
Enhanced Progression of Early Carotid Atherosclerosis Is Related to
Chlamydia pneumoniae
(Taiwan Acute Respiratory) Seropositivity
Authors: Sander Dirk , Winbeck Kerstin , Klingelhöfer Jürgen , Etgen Thorleif , Conrad Bastian
Published: June 2012

Background
—
Chlamydia pneumoniae
(Cp) infection has been associated with atherosclerosis and has been proposed as a possible additional cardiovascular risk factor. However, the relationship between Cp seropositivity and the progression of early carotid atherosclerosis is not unequivocally clarified.

Methods and Results
—We evaluated the association between serological detection of Cp IgG and/or IgA antibodies and the progression of the intima-media thickness (IMT) of the common carotid artery using duplex ultrasonography in a prospective study with a follow-up of 3 years in 272 consecutive patients with cerebrovascular disease. Cp-seropositive patients showed a significantly enhanced progression of the IMT even after adjustment for other cardiovascular risk factors (0.12 mm/y [95% CI 0.11 to 0.14] versus 0.07 mm/y [0.05 to 0.09];
P
<0.005). Patients with increased C-reactive protein (≥0.5 mg/dL) and Cp seropositivity showed the most pronounced IMT progression. Multivariate regression analysis revealed Cp seropositivity to be an independent risk factor for progression of early carotid atherosclerosis. Cox proportional-hazard regression analysis demonstrated a significantly increased rate of cerebrovascular and cardiovascular events in patients with Cp seropositivity, particularly in patients with increased C-reactive protein levels.

Conclusions
—Our data support the importance of chronic inflammation and infection for the early stages of atherosclerotic development.
QTc Interval as a Guide to Select Those Patients With Congestive Heart Failure and Reduced Left Ventricular Systolic Function Who Will Benefit From Antiarrhythmic Treatment With Dofetilide
Authors: Brendorp Bente , Elming Hanne , Jun Li , Køber Lars , Malik Marek , Jensen Gorm Boje , Torp-Pedersen Christian
Published: June 2012

Background
—A prolonged QTc interval is considered a contraindication for class III antiarrhythmic drugs, but the influence of a normal or a slightly increased baseline QTc interval on the risk or benefit of treatment with a class III antiarrhythmic drug is not sufficiently clarified.

Methods and Results
—This prospectively defined substudy included 703 patients enrolled in the Danish Investigations of Arrhythmia and Mortality on Dofetilide-Congestive Heart Failure (DIAMOND-CHF) study. Patients included had moderate to severe CHF and reduced left ventricular systolic function. Baseline QTc interval was measured before randomization to either dofetilide, a new class III antiarrhythmic drug, or placebo. During a median follow-up of 18 months (minimum 1 year), 285 patients (41%) died. Baseline QTc interval had no prognostic value on survival in placebo-treated patients. In dofetilide-treated patients, a baseline QTc interval <429 ms was associated with a significant risk reduction (risk ratio 0.4, 95% CI 0.3 to 0.8). With increasing QTc interval, the risk increased gradually, and for QTc interval >479 ms, risk ratio was 1.3 (0.8 to 1.9).

Conclusions
—A baseline QTc interval within normal limits is associated with a marked reduction of mortality in patients with CHF and left ventricular systolic dysfunction treated with dofetilide. This is a potentially important indication of which patients with CHF might benefit from prophylactic treatment with an antiarrhythmic drug.
Heart Rate and Cardiac Rhythm Relationships With Bisoprolol Benefit in Chronic Heart Failure in CIBIS II Trial
Authors: Lechat Philippe , Hulot Jean-Sébastien , Escolano Sylvie , Mallet Alain , Leizorovicz Alain , Werhlen-Grandjean Marie , Pochmalicki Gilbert , Dargie Henry
Published: June 2012

Background
—β-Blockade–induced benefit in heart failure (HF) could be related to baseline heart rate and treatment-induced heart rate reduction, but no such relationships have been demonstrated.

Methods and Results
—In CIBIS II, we studied the relationships between baseline heart rate (BHR), heart rate changes at 2 months (HRC), nature of cardiac rhythm (sinus rhythm or atrial fibrillation), and outcomes (mortality and hospitalization for HF). Multivariate analysis of CIBIS II showed that in addition to β-blocker treatment, BHR and HRC were both significantly related to survival and hospitalization for worsening HF, the lowest BHR and the greatest HRC being associated with best survival and reduction of hospital admissions. No interaction between the 3 variables was observed, meaning that on one hand, HRC-related improvement in survival was similar at all levels of BHR, and on the other hand, bisoprolol-induced benefit over placebo for survival was observed to a similar extent at any level of both BHR and HRC. Bisoprolol reduced mortality in patients with sinus rhythm (relative risk 0.58,
P
<0.001) but not in patients with atrial fibrillation (relative risk 1.16,
P
=NS). A similar result was observed for cardiovascular mortality and hospitalization for HF worsening.

Conclusions
—BHR and HRC are significantly related to prognosis in heart failure. β-Blockade with bisoprolol further improves survival at any level of BHR and HRC and to a similar extent. The benefit of bisoprolol is questionable, however, in patients with atrial fibrillation.
Lysophosphatidylcholine and Reactive Oxygen Species Mediate the Synergistic Effect of Mildly Oxidized LDL With Serotonin on Vascular Smooth Muscle Cell Proliferation
Authors: Watanabe Takuya , Pakala Rajbabu , Koba Shinji , Katagiri Takashi , Benedict Claude R.
Published: June 2012

Background
—Mild oxidation of LDL enhances its atherogenic potential and induces a synergistic interaction with serotonin (5HT) on vascular smooth muscle cell (VSMC) proliferation. Because of its complex chemical nature, the mitogenic components of mildly oxidized LDL (moxLDL) remain unclear.

Methods and Results
—We examined both the effects of lysophosphatidylcholine (LPC) and hydrogen peroxide (H
2
O
2
), a donor of reactive oxygen species, as major components of moxLDL and their interactions with 5HT on VSMC proliferation. Growth-arrested VSMCs were incubated with different concentrations of moxLDL, LPC, H
2
O
2
, or LPC with H
2
O
2
in the absence or presence of 5HT. DNA synthesis in VSMCs was examined by [
3
H]thymidine incorporation. MoxLDL, LPC, H
2
O
2
, and 5HT stimulated DNA synthesis in a dose-dependent manner. MoxLDL had a maximal stimulatory effect at a concentration of 5 μg/mL (211%), LPC at 15 μmol/L (156%), H
2
O
2
at 5 μmol/L (179%), and 5HT at 50 μmol/L (205%). Added together, moxLDL (50 ng/mL) and 5HT (50 μmol/L) synergistically increased DNA synthesis (443%). Coincubation of LPC (1 μmol/L) with H
2
O
2
(0.5 μmol/L) and 5HT (5 μmol/L) resulted in a synergistic increase in DNA synthesis (439%), which was nearly equal to that of moxLDL with 5HT (443%). The combined effects of LPC, H
2
O
2
, and 5HT on DNA synthesis were completely reversed by the combined use of an antioxidant,
N
-acetylcysteine (400 μmol/L) or butylated hydroxytoluene (20 μmol/L), with a 5HT
2
receptor antagonist,
LY281067
(10 μg/mL).

Conclusions
—Our results suggest that both LPC and reactive oxygen species may contribute to the mitogenic effect of moxLDL on VSMCs and its synergistic effect with 5HT.
Improvement of Defibrillation Efficacy and Quantification of Activation Patterns During Ventricular Fibrillation in a Canine Heart Failure Model
Authors: Huang Jian , Rogers Jack M. , Killingsworth Cheryl R. , Walcott Gregory P. , KenKnight Bruce H. , Smith William M. , Ideker Raymond E.
Published: June 2012

Background
—Little is known about the effects of heart failure (HF) on the defibrillation threshold (DFT) and the characteristics of activation during ventricular fibrillation (VF).

Methods and Results
—HF was induced by rapid right ventricular (RV) pacing for at least 3 weeks in 6 dogs. Another 6 dogs served as controls. Catheter defibrillation electrodes were placed in the RV apex, the superior vena cava, and the great cardiac vein (CV). An active can coupled to the superior vena cava electrode served as the return for the RV and CV electrodes. DFTs were determined before and during HF for a shock through the RV electrode with and without a smaller auxiliary shock through the CV electrode. VF activation patterns were recorded in HF and control animals from 21×24 unipolar electrodes spaced 2 mm apart on the ventricular epicardium. Using these recordings, we computed a number of quantitative VF descriptors. DFT was unchanged in the control dogs. DFT energy was increased 79% and 180% (with and without auxiliary shock, respectively) in HF compared with control dogs. During but not before HF, DFT energy was significantly lowered (21%) by addition of the auxiliary shock. The VF descriptors revealed marked VF differences between HF and control dogs. The differences suggest decreased excitability and an increased refractory period during HF. Most, but not all, descriptors indicate that VF was less complex during HF, suggesting that VF complexity is multifactorial and cannot be expressed by a scalar quantity.

Conclusions
—HF increases the DFT. This is partially reversed by an auxiliary shock. HF markedly changes VF activation patterns.
Decreased Sarcoplasmic Reticulum Calcium Content Is Responsible for Defective Excitation-Contraction Coupling in Canine Heart Failure
Authors: Hobai Ion A. , O’Rourke Brian
Published: June 2012

Background
—Altered excitation-contraction (E-C) coupling in canine pacing-induced heart failure involves decreased sarcoplasmic reticulum (SR) Ca uptake and enhanced Na/Ca exchange, which could be expected to decrease SR Ca content (Ca
SR
) and may explain the reduced intracellular Ca (Ca
i
) transient. Studies in other failure models have suggested that the intrinsic coupling between L-type Ca current (
I
Ca,L
) and SR Ca release is reduced without a change in SR Ca load. The present study investigates whether Ca
SR
and/or coupling is altered in midmyocardial myocytes from failing canine hearts (F).

Methods and Results
—Myocytes were indo-1–loaded via patch pipette (37°C), and Ca
i
transients were elicited with voltage-clamp steps applied at various frequencies.
I
Ca,L
density was not significantly decreased in F, but steady-state Ca
i
transients were reduced to 20% to 40% of normal myocytes (N). Ca
SR
, measured by integrating Na/Ca exchange currents during caffeine-induced release, was profoundly decreased in F, to 15% to 25% of N. When Ca
SR
was normalized in F by preloading in 5 mmol/L external Ca before a test pulse at 2 mmol/L Ca, a normal-amplitude Ca
i
transient was elicited. E-C coupling gain was dependent on Ca
SR
but was affected similarly in both groups, indicating that intrinsic coupling is unaltered in F.

Conclusions
—A decrease in Ca
SR
is sufficient to explain the diminished Ca
i
transients in F, without a change in the effectiveness of coupling. Therefore, therapeutic approaches that increase Ca
SR
may be able to fully correct the Ca handling deficit in heart failure.
Left Ventricular Hypertrophy Decreases Slowly but Not Rapidly Activating Delayed Rectifier Potassium Currents of Epicardial and Endocardial Myocytes in Rabbits
Authors: Xu Xiaoping , Rials Seth J. , Wu Ying , Salata Joseph J. , Liu Tengxian , Bharucha David B. , Marinchak Roger A. , Kowey Peter R.
Published: June 2012

Background
—Delayed rectifier K
+
currents are critical to action potential (AP) repolarization. The present study examines the effects of left ventricular hypertrophy (LVH) on delayed rectifier K
+
currents and their contribution to AP repolarization in both epicardial (Epi) and endocardial (Endo) myocytes.

Methods and Results
—LVH was induced in rabbits by a 1-kidney removal, 1-kidney vascular clamping method. Slowly (
I
Ks
) and rapidly (
I
Kr
) activating delayed rectifier K
+
currents were recorded by the whole-cell patch-clamp technique, and APs were recorded by the microelectrode technique. In normal rabbit left ventricular myocytes,
I
Ks
densities were larger in Epi than in Endo (1.1±0.1 versus 0.43±0.07 pA/pF), whereas
I
Kr
density was similar between Epi and Endo (0.31±0.05 versus 0.36±0.07 pA/pF) at 20 mV. LVH reduced
I
Ks
density to a similar extent (≈40%) in both Epi and Endo but had no significant effect on
I
Kr
in either Epi or Endo. Consequently,
I
Kr
was expected to contribute more to AP repolarization in LVH than in control. This was confirmed by specific
I
Kr
block with dofetilide, which prolonged AP significantly more in LVH than in control (31±3% versus 18±2% in Epi; 53±6% versus 32±4% in Endo at 2 Hz). In contrast, L-768,673 (a specific
I
Ks
blocker) prolonged AP less in LVH than in control. The very small
I
Ks
density in Endo with LVH is consistent with the greater incidence of early afterdepolarizations induced in this region by dofetilide.

Conclusions
—LVH induces a decrease in
I
Ks
density and increases the propensity to develop early afterdepolarizations, especially in Endo.
Role of Endothelial Nitric Oxide in Shear Stress–Induced Vasodilation of Human Microvasculature
Authors: Paniagua Oscar A. , Bryant Melissa B. , Panza Julio A.
Published: June 2012

Background
—It has been proposed that flow-mediated shear stress regulates vascular tone; however, whether this operates in the human microcirculation is unknown. This study was designed to investigate the effect of shear stress on human microvascular tone, to assess the contribution of nitric oxide (NO), and to determine whether this mechanism is defective in hypertension and in hypercholesterolemia.

Methods and Results
—In 9 normal controls (NC), 11 hypertensive patients (HT), and 12 hypercholesterolemic patients (HChol), arteries (internal diameter 201±26 μm) isolated from gluteal fat biopsies were cannulated and perfused in chambers. Shear stress was induced by increasing the flow rate from 1 to 50 μL/min after preconstriction with norepinephrine (NE). Arterial internal diameter was expressed as percent of NE-induced constriction. In NC, shear stress induced flow-dependent vasodilation from 23±9% at 1 μL/min to 53±14% at 50 μL/min (
P
<0.0001), which was abolished by endothelial removal. The NO synthase inhibitor
Nω
-nitro-
l
-arginine (L-NNA) significantly blunted this response (mean vasodilation decreased from 27±6% to 6±9%;
P
=0.04). HT had significant impairment of flow-mediated dilation (mean vasodilation 5±6%;
P
=0.01 versus NC), which was not affected by L-NNA. HChol had preserved flow-mediated vasodilation (mean vasodilation 24±7%;
P
=0.56 versus NC), but this was not significantly modified by L-NNA.

Conclusions
—In the human microvasculature, shear stress induces endothelium-dependent, NO-mediated vasodilation. This phenomenon is blunted in HT patients because of reduced activity of NO. In contrast, the HChol microvasculature has preserved shear stress-induced dilation despite diminished NO activity.
Increased Vascular Endothelial Growth Factor 165 Binding to Kinase Insert Domain–Containing Receptor After Infection of Human Endothelial Cells by Recombinant Adenovirus Encoding the
Vegf

165

Gene
Authors: Weisz Anat , Koren Belly , Cohen Tzafra , Neufeld Gera , Kleinberger Tamar , Lewis Basil S. , Flugelman Moshe Y.
Published: June 2012

Background
—The angiogenic effect of vascular endothelial growth factor (VEGF
165
) is mediated mainly through the high-affinity tyrosine kinase receptor VEGF-R2 (KDR/
flk-1
). This study examined the effects of VEGF overexpression by primary human endothelial cells (ECs), which do not express VEGF under physiological conditions, on cell proliferation, VEGF binding to the kinase insert domain–containing receptor (KDR), and KDR expression.

Methods and Results
—Human primary ECs and SMCs were infected by recombinant adenoviral vector encoding VEGF
165
(rAdVEGF). Proliferation rate, bromodeoxyuridine incorporation,
125
I-labeled VEGF
165
binding to the KDR receptor, and KDR expression were tested in the infected cells and in cells supplemented with VEGF protein. Enhanced proliferation and a significant increase in
125
I-VEGF
165
binding to the KDR receptor were induced by rAdVEGF infection of ECs (autocrine effect) as well as by addition of recombinant VEGF
165
to noninfected cells. Infection of ECs by rAdVEGF led to posttranscriptional upregulation of the KDR receptor, whereas KDR mRNA expression levels remained unchanged. Similar effects were observed with supplemented recombinant VEGF
165
to noninfected ECs; nevertheless, this phenomenon occurred only with high VEGF
165
concentrations (10 ng/mL).

Conclusions
—The effect of VEGF
165
on proliferation and upregulation of KDR receptor expression demonstrated an autocrine phenomenon of EC sensitization. The fact that high concentrations of VEGF may be achieved in vivo by local continuous overexpression of VEGF
165
by gene transfer emphasizes the potential advantage of gene transfer over protein supplementation for therapeutic angiogenesis.
Effects of L-749,329, an ET
A
/ET
B
Endothelin Receptor Antagonist, in a Porcine Coronary Artery Injury Model of Vascular Restenosis
Authors: Huckle William R. , Drag Marlene D. , Acker Wayne R. , Powers Michele , McFall Rosemary C. , Holder Daniel J. , Walsh Thomas F. , Schwartz Robert S. , Greenlee William J. , Johnson Robert G.
Published: June 2012

Background
—Previous studies in animal models of angioplasty have suggested a role in neointimal hyperplasia for endothelins (ETs), potent vasoconstricting peptides that also exert growth-promoting effects. The present studies were undertaken to test the hypothesis that endothelin receptor blockade can reduce neointimal thickening in injured porcine coronary arteries.

Methods and Results
—An ET
A
/ET
B
antagonist, L-749,329, was evaluated as an inhibitor of intimal thickening in a porcine balloon/stent model of coronary artery injury. L-749,329 competitively inhibited [
125
I]ET-1 binding to porcine ET
A
(IC
50
≈0.3 nmol/L) or ET
B
(IC
50
≈20 nmol/L) receptors and inhibited ET-1–stimulated signaling in cell culture. In anesthetized pigs, big ET-1–stimulated increases in systemic blood pressure were totally inhibited after intravenous infusion of L-749,329 (≥0.2 mg · kg
−1
· h
−1
). In vascular injury studies, pigs were treated with vehicle or L-749,329 (1 mg · kg
−1
· h
−1
) beginning 2 days before and continuing 28 days after experimental angioplasty. Left anterior descending, left circumflex, and/or right coronary arteries were injured by inflation of an angioplasty balloon wrapped with a coiled metallic stent. After 28 days, mean neointimal thickness in the L-749,329–treated group was reduced by 9.0% compared with vehicle-treated controls, but this effect was not statistically significant (
P
=0.13).

Conclusions
—Blockade of endothelin receptors for 28 days with only a mixed ET
A
/ET
B
receptor antagonist is insufficient to substantially inhibit intimal hyperplasia after balloon/stent coronary artery injury in the pig, in contrast to results with a selective ET
A
antagonist. The effects of selective or mixed ET
A
/ET
B
antagonists in diseased vessels remain to be determined in this model.
Vascular Effects of Synthetic or Natural Progestagen Combined With Conjugated Equine Estrogen in Healthy Postmenopausal Women
Authors: Koh Kwang Kon , Jin Dong Kyu , Yang Seong Hee , Lee Seon-Kyu , Hwang Hee Young , Kang Moon Ho , Kim Wan , Kim Dae Sung , Choi In Suck , Shin Eak Kyun
Published: June 2012

Background
—Synthetic, not natural, progestagen may negate the favorable effects of estrogen. Nonetheless, observational studies report no differences in risk for clinical cardiovascular events between users of unopposed estrogen and users of estrogen combined with synthetic progestin.

Methods and Results
—In a double-blind study, we randomly assigned 20 healthy postmenopausal women to micronized progesterone (MP) 200 mg or medroxyprogesterone acetate (MPA) 10 mg for 10 days with conjugated equine estrogen (CEE) 0.625 mg for 25 days and the remaining 5 days off cyclically during 2 months, followed by crossover to the alternate therapy. CEE+MP and CEE+MPA significantly improved the percent flow-mediated dilator response to hyperemia relative to baseline measurements (
P
=0.004 by ANOVA) by a similar degree (
P
=0.863). Both therapies significantly decreased E-selectin, intercellular adhesion molecule (ICAM)-1, and vascular cell adhesion molecule (VCAM)-1 levels from baseline values (
P
<0.001,
P
=0.048, and
P
=0.016 by ANOVA, respectively) by a similar degree (
P
=0.977 for ICAM-1 and
P
=0.541 for VCAM-1, respectively). CEE+MPA decreased E-selectin levels more than CEE+MP did (
P
=0.040). Both therapies significantly decreased monocyte chemoattractant protein-1 levels from baseline values (
P
<0.005 by ANOVA) by a similar degree (
P
=0.194). Both therapies significantly decreased tissue factor antigen and increased tissue factor activity levels from baseline values (
P
=0.003 and
P
<0.001 by ANOVA, respectively) by a similar degree (
P
=0.652 for antigen and
P
=0.173 for activity). Both therapies significantly lowered plasma plasminogen activator inhibitor-1 levels from baseline values (
P
<0.001 by ANOVA) by a similar degree (
P
=0.533).

Conclusions
—CEE+MP and CEE+MPA provide similar improvement in endothelium-dependent vasodilator responsiveness and effects on markers of inflammation, hemostasis, and fibrinolysis inhibition in healthy postmenopausal women.
Assessment of Myocardial Postreperfusion Viability by Intravenous Myocardial Contrast Echocardiography
Authors: Ohmori Koji , Cotter Bruno , Leistad Elisabeth , Bhargava Valmik , Wolf Paul L. , Mizushige Katsufumi , DeMaria Anthony N.
Published: June 2012

Background
—Although defects on intracoronary myocardial contrast echocardiography (MCE) indicate loss of viability after reperfusion, opacified segments may also exhibit persistent dyssynergy. Therefore, we related the intensity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissue by postreperfusion MCE.

Methods and Results
—MCE was performed by intravenous injection of 0.15 mL/kg QW7437 in 14 dogs who underwent 3-hour coronary occlusion followed by 3-hour reperfusion. At baseline and 3 hours after reperfusion, midventricular short-axis images were digitized and segmented. Infarction fraction (IF) for each segment was determined by triphenyltetrazolium chloride stain. Of 224 segments, 140 showed no or small infarction and served as a control group. Of 84 segments with significant infarction (IF>30%), 52 exhibited a defect on MCE, and 32 exhibited no defect. Echo texture was quantified by computing entropy based on the co-occurrence matrix analysis of gray-level pairs within each segment. Three hours after reperfusion, average and maximal entropies in the infarct segments without opacification defects were significantly higher than control levels. Histologically, the degree of intracapillary erythrocyte stasis was less in this group than in the infarcted segments with MCE defects with similar magnitude of tissue injuries.

Conclusions
—Opacification defects by MCE may be present or absent in myocardium with histologically confirmed infarction. The texture of MCE from opacified but infarcted myocardium differed significantly from control segments and may assist in determination of segmental viability after reperfusion.
Electrical Storm Presages Nonsudden Death
Authors: Exner Derek V. , Pinski Sergio L. , Wyse D. George , Renfroe Ellen Graham , Follmann Dean , Gold Michael , Beckman Karen J. , Coromilas James , Lancaster Scott , Hallstrom Alfred P.
Published: June 2012

Background
—Electrical storm, multiple temporally related episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF), is a frequent problem among recipients of implantable cardioverter defibrillators (ICDs). However, insufficient data exist regarding its prognostic significance.

Methods and Results
—This analysis includes 457 patients who received an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial and who were followed for 31±13 months. Electrical storm was defined as ≥3 separate episodes of VT/VF within 24 hours. Characteristics and survival of patients surviving electrical storm (n=90), those with VT/VF unrelated to electrical storm (n=184), and the remaining patients (n=183) were compared. The 3 groups differed in terms of ejection fraction, index arrhythmia, revascularization status, and baseline medication use. Survival was evaluated using time-dependent Cox modeling. Electrical storm occurred 9.2±11.5 months after ICD implantation, and most episodes (86%) were due to VT. Electrical storm was a significant risk factor for subsequent death, independent of ejection fraction and other prognostic variables (relative risk [RR], 2.4; 95% confidence interval [CI], 1.3 to 4.2;
P
=0.003), but VT/VF unrelated to electrical storm was not (RR, 1.0; 95% CI, 0.6 to 1.7;
P
=0.9). The risk of death was greatest 3 months after electrical storm (RR, 5.4; 95% CI, 2.4 to 12.3;
P
=0.0001) and diminished beyond this time (RR, 1.9; 95% CI, 1.0 to 3.6;
P
=0.04).

Conclusions
—Electrical storm is an important, independent marker for subsequent death among ICD recipients, particularly in the first 3 months after its occurrence. However, the development of VT/VF unrelated to electrical storm does not seem to be associated with an increased risk of subsequent death.
Oxidized LDL Inhibits Vascular Endothelial Growth Factor–Induced Endothelial Cell Migration by an Inhibitory Effect on the Akt/Endothelial Nitric Oxide Synthase Pathway
Authors: Chavakis Emmanouil , Dernbach Elisabeth , Hermann Corinna , Mondorf Ulrich F. , Zeiher Andreas M. , Dimmeler Stefanie
Published: June 2012

Background
—Oxidized LDL (oxLDL) inhibits endothelial cell (EC) migration. Stimulating ECs with vascular endothelial growth factor (VEGF) leads to the activation of Akt/protein kinase B, which in turn activates endothelial nitric oxide synthase (eNOS) by phosphorylation on serine 1177. VEGF-induced cell migration is dependent on the generation of nitric oxide (NO). Therefore, we investigated whether oxLDL affects EC migration by an inhibitory effect on the Akt/eNOS pathway.

Methods and Results
—During an in vitro “scratched wound assay,” oxLDL dose-dependently inhibited the VEGF-induced migration of human umbilical vein endothelial cells. Western blot analysis revealed that oxLDL dose- and time-dependently led to dephosphorylation and thus deactivation of Akt. Moreover, oxLDL inhibited the VEGF-induced generation of NO, as detected and quantified using a fluorescent NO indicator, 4,5-diaminofluorescein diacetate. Overexpression of a constitutively active Akt construct (Akt T308D/S473D) or a phosphomimetic eNOS construct (eNOS S1177D) almost completely reversed the inhibitory effect of oxLDL on VEGF-induced EC migration and NO generation.

Conclusions
—Our data indicate that oxLDL-induced dephosphorylation of Akt, followed by impaired eNOS activation, reduces the intracellular level of NO and thereby inhibits VEGF-induced EC migration.
Potentiation of Baroreceptor Reflex Response by Heat Shock Protein 70 in Nucleus Tractus Solitarii Confers Cardiovascular Protection During Heatstroke
Authors: Li Pei-Lun , Chao Yung-Mei , Chan Samuel H. H. , Chan Julie Y. H.
Published: June 2012

Background
—Whereas hypotension and bradycardia seen during the onset of heatstroke may be protected by prior induction of heat shock protein 70 (HSP70) in the brain, the underlying mechanism is not fully understood. We evaluated the hypothesis that HSP70 may confer cardiovascular protection during heatstroke by potentiating the baroreceptor reflex (BRR) control of peripheral hemodynamic performance.

Methods and Results
—Adult male Sprague-Dawley rats subjected to a brief hyperthermic heat shock (HS; 42°C for 15 minutes) induced discernible expression of HSP70 in the bilateral nucleus tractus solitarii (NTS), the terminal site in the brain stem for primary baroreceptor afferents. This HSP70 expression was detected at 8 hours, peaked at 24 hours, and returned to baseline by 48 hours after HS. Brief hyperthermia also significantly potentiated the BRR response in a temporal profile that correlated positively with changes in HSP70 expression at the NTS. Prior HS also appreciably alleviated hyperthermia, severe hypotension, and bradycardia manifested during the onset of heatstroke (45°C for 60 minutes) elicited 24 hours later. Microinjection bilaterally of anti-HSP70 antiserum (1:20) into the NTS or denervation of the sinoaortic baroreceptor afferents significantly reversed the enhancement of BRR response and cardiovascular protection during heatstroke induced by prior HS.

Conclusions
—These results suggest that HS-induced expression of HSP70 in the NTS may alleviate severe hypotension and bradycardia exhibited during the onset of heatstroke by potentiating both the sensitivity and capacity of BRR response.
Absence of 12/15-Lipoxygenase Expression Decreases Lipid Peroxidation and Atherogenesis in Apolipoprotein E–Deficient Mice
Authors: Cyrus Tillmann , Praticò Domenico , Zhao Lei , Witztum Joseph L. , Rader Daniel J. , Rokach Joshua , FitzGerald Garret A. , Funk Colin D.
Published: June 2012

Background
—The enzyme 12/15-lipoxygenase (12/15-LO) has been implicated in the oxidative modification of LDL. In a murine model, we tested the hypothesis that deletion of 12/15-LO decreases atherogenesis by reducing oxidant stress, as measured by 2 indices of lipid peroxidation: isoprostane generation and autoantibody formation to malondialdehyde (MDA)-LDL, an epitope of LDL formed as a result of oxidative modification.

Methods and Results
—12/15-LO–deficient (12/15-LO
−/−
) mice were crossed with apolipoprotein E–deficient (apoE
−/−
) mice. At 10 weeks of age, atherosclerotic lesion initiation was significantly delayed in the double-knockout mice. The rate of lesion progression was diminished at 8 and 12 months, and even at 15 months, lesion size was reduced 50% (
P
<0.0005) compared with control apoE
−/−
mice. The urinary and plasma levels of the specific isoprostane 8,12-iso-iPF
2α
-VI, as well as IgG autoantibodies against MDA-LDL, were significantly reduced in the double-deficient mice in parallel with decreased atherosclerosis at all time points from 10 weeks to 15 months of age compared with apoE
−/−
controls.

Conclusions
—Enzymatic action of 12/15-LO contributes significantly to atherosclerotic lesion initiation and propagation in this murine model. Strong positive correlations exist between lesion size, isoprostane levels, and MDA-LDL autoantibodies, providing in vivo evidence for an enzymatic (12/15-LO) component to lipid peroxidation and atherogenesis.