bluuebunny/crossref_metadata_2025 huggingface dataset:
Estrogen Promotes Angiogenic Activity in Human Umbilical Vein Endothelial Cells In Vitro and in a Murine Model
Authors: Morales David E. , McGowan Kelly A. , Grant Derrick S. , Maheshwari Shailendra , Bhartiya Deepa , Cid Maria C. , Kleinman Hynda K. , Schnaper H. William
Published: June 2012

Background
Angiogenesis is a critical event in wound healing, tumor growth, and the inflammatory vasculitides. Since women have a higher incidence of many vasculitic diseases, we examined the effects of female sex steroids, particularly estradiol, on human umbilical vein endothelial cell (HUVEC) behavior in vitro and on angiogenesis in vivo.

Methods and Results
HUVECs were grown in estrogen-free medium before each assay. Exogenous 17β-estradiol (1 to 5 nmol/L) increased cell attachment to laminin, types I and IV collagen, and fibronectin, as well as to tissue culture plastic. After a confluent monolayer of cells was “wounded” by scraping, estradiol-treated (10
−8
mol/L) cells migrated into the wound three times faster than untreated cells. Cell proliferation on plastic and on laminin increased threefold to fivefold, respectively, in the presence of estradiol. Estradiol also enhanced the ability of HUVECs to organize into tubular networks when plated on a reconstituted basement membrane, Matrigel. Estradiol effects on both the “wounding” assay and tube formation were blocked by the specific estrogen receptor antagonist ICI 182,780. Ovariectomy markedly decreased in vivo vascularization of Matrigel plugs coinjected with basic fibroblast growth factor in mice. With estrogen replacement, angiogenesis was increased to the levels observed in nonovariectomized mice.

Conclusions
These studies demonstrate that, in vitro and in vivo, estradiol enhances endothelial cell activities important in neovascularization and suggest a promoting influence of estrogens on angiogenesis.
In Vivo Evidence of an Endothelin-Induced Vasopressor Tone After Inhibition of Nitric Oxide Synthesis in Rats
Authors: Richard Vincent , Hogie Manuela , Clozel Martine , Löffler Bernd-Michael , Thuillez Christian
Published: June 2012

Background
Continuous production of nitric oxide (NO) from endothelial cells permanently inhibits the synthesis and the vasoconstrictor effects of endothelin. Thus, inhibition of NO synthesis might unmask a vasopressor response to endothelin. To assess whether endothelin contributes to the pressor response induced by inhibition of NO synthesis, we tested whether bosentan, a nonpeptide antagonist of ET
A
and ET
B
endothelin receptors, affected the hypertensive response induced by the NO synthase inhibitor
N
G
-nitro
l
-arginine methyl ester (L-NAME).

Methods and Results
Anesthetized rats received increasing doses of L-NAME (0.1 to 3 mg · kg
−1
) in the absence or the presence of bosentan (3 mg · kg
−1
IV 15 minutes before L-NAME). Bosentan itself did not affect blood pressure. L-NAME induced a dose-dependent increase in mean arterial pressure (percent increase from baseline after 3 mg · kg
−1
, 25±5%), and this was reduced by bosentan (13±3%;
P
<.05) or by the selective ET
A
antagonist BQ-123 (3 mg · kg
−1
: controls, 25±4%; BQ-123, 14±5%;
P
<.01). In contrast, bosentan did not affect the pressor response to phenylephrine (1 to 100 μg · kg
−1
). The response to L-NAME (3 mg · kg
−1
) was also reduced by bosentan in ganglion-blocked (chlorisondamine 2.5 mg · kg
−1
: controls, 89±10%; bosentan, 45±7%) or pithed rats (controls, 165±9%; bosentan, 85±12%;
P
<.01). Bosentan also inhibited the pressor response to another inhibitor of NO synthesis,
N
G
-nitro
l
-arginine (3 mg · kg
−1
) in normal (controls, 24±5%; bosentan, 10±3%;
P
<.01) or ganglion-blocked (controls, 86±13%; bosentan, 25±8%;
P
<.01) rats. Finally, L-NAME induced a modest increase in plasma levels of endothelin-1 (controls, 26.8±4.1 pg · mL
−1
; L-NAME, 38.5±3.3 pg · mL
−1
;
P
<.05).

Conclusions
These experiments demonstrate that inhibition of NO synthesis unmasks a tonic pressor influence of endothelin, suggesting that this peptide could play a major role in pathophysiological situations associated with an impaired formation of NO.
Residual
201
Tl Activity in Irreversible Defects as a Marker of Myocardial Viability
Authors: Zimmermann Rainer , Mall Gerhard , Rauch Bernhard , Zimmer Gisela , Gabel Michael , Zehelein Jörg , Bubeck Bernd , Tillmanns Harald , Hagl Siegfried , Kübler Wolfgang
Published: June 2012

Background
The objective of the present study was to characterize the relation between the residual
201
Tl activity in irreversible perfusion defects and the extent of irreversible myocardial damage indicated by the volume fraction of myocardial interstitial fibrosis in patients with chronic coronary artery disease.

Methods and Results
Stress planar
201
Tl scintigraphy with tracer reinjection at rest was performed in 37 patients with ≥75% stenosis of the left anterior descending coronary artery, and anteroseptal
201
TI activity was quantified by computer-assisted placement of regions of interest from the serial myocardial images. During coronary artery bypass grafting (performed within 6±3 weeks after scintigraphy), two transmural biopsy specimens were taken from the anterior wall of the left ventricle and the amount of interstitial fibrosis was assessed by use of light microscopic morphometry. A wide spectrum of interstitial fibrosis was obtained, ranging from 15 vol% to 60 vol%. Interstitial fibrosis was similar in patients with reversible (n=11) or irreversible (n=15) tracer defects in conventional stress-redistribution images. However, interstitial fibrosis was significantly lower in patients who had enhanced regional
201
Tl activity after tracer reinjection compared with those who did not have enhancement of tracer activity after reinjection (28±8 vol%, n=7, versus 41±12 vol%, n=8;
P
=.031). The correlation between relative poststenotic
201
Tl activity and interstitial fibrosis after tracer reinjection was significantly improved compared with conventional redistribution images (
r
=−.622 versus
r
=−.851, n=15;
P
<.01).

Conclusions
The present data demonstrate that the level of regional
201
Tl activity in redistribution and, in particular, reinjection images is significantly related to the mass of preserved viable myocytes in poststenotic left ventricular myocardium. Therefore, the residual
201
Tl activity provides information about viability within irreversible perfusion defects and may itself serve as marker of myocardial viability.
Increased Early Mortality in Women Undergoing Cardiac Transplantation
Authors: Wechsler Mindy E. , Giardina Elsa-Grace V. , Sciacca Robert R. , Rose Eric A. , Barr Mark L.
Published: June 2012

Background
To evaluate factors that explain sex differences affecting mortality after cardiac transplantation, a retrospective analysis of adult patients undergoing orthotopic cardiac transplantation was undertaken at the Columbia-Presbyterian Medical Center.

Methods and Results
The study population consisted of 379 patients (75 women, 304 men) ≥18 years of age who survived for ≥48 hours after undergoing orthotopic cardiac transplantation between March 1985 and March 1992. The following were analyzed: incidence of death and treated rejection episodes, donor and recipient cytomegalovirus (CMV) matches, use of OKT3 induction therapy, and donor and recipient HLA mismatches. Women 49±12 years old and men 47±12 years old were characterized by differences in race and diagnosis. Women were more likely to be nonwhite (
P
<.01) and have idiopathic cardiomyopathy than were men (
P
<.01). A trend toward an increase in first-year rejection frequency was seen in women compared with men (
P
=.08). Overall actuarial survival was significantly reduced in women after transplantation (
P
<.05). At 36 months, female actuarial survival was 64±7% versus 76±3% for men (
P
<.05). The majority of patients in this study did not receive CMV prophylaxis. Univariate analysis revealed that only CMV(+) donor status and the use of OKT3 induction therapy affected survival in women. Multivariate analysis revealed a marked reduction in survival in female recipients of CMV(+) donors given OKT3 induction therapy. At 36 months, only 25% of women were still alive compared with 86% of women with neither risk factor (
P
<.001). Even without OKT3 induction there was markedly reduced survival in women with mismatched CMV status, ie, CMV(−) recipients of CMV(+) donors; 17% survival after 36 months versus 86% in women who were CMV(+) recipients (
P
<.05). Although at this institution during the study time period, CMV prophylaxis was not routinely employed and OKT3 induction was selectively used in higher-risk patients, conclusions regarding differences in outcome that are sex dependent are valid.

Conclusions
(1) Women are at risk for reduced actuarial survival up to 3 years after cardiac transplantation. (2) Univariate analysis shows that women are selectively at risk for death when receiving hearts from CMV(+) donors and after receiving OKT3 induction therapy. (3) Multivariate analysis reveals that women are at even greater risk for death when receiving hearts from CMV(+) donors in conjunction with OKT3 induction therapy. (4) In the absence of OKT3 use, the greatest risk of death occurs in CMV(−) women transplanted with CMV(+) donor hearts. (5) When female to male survival curves are compared, factors that influenced survival in women did not appear to be problematic in men.
Characteristics of the Ventricular Insertion Sites of Accessory Pathways With Anterograde Decremental Conduction Properties
Authors: Haı̈ssaguerre Michel , Cauchemez Bruno , Marcus Frank , Le Métayer Philippe , Lauribe Philippe , Poquet Franck , Gencel Laurent , Clémenty Jacques
Published: June 2012

Background
Accessory pathways (APs) with anterograde decremental conduction properties referred to as Mahaim fibers have recently been recognized as originating from the right lateral atrium. Little information is available about their distal insertion. The purpose of this study was to determine the different kinds of APs involved and the characteristics of their distal insertion site.

Methods and Results
Twenty-one patients (mean age, 28±13 years) with reciprocating tachycardia or atrial fibrillation were studied. Right-sided atrial and/or ventricular endocardial mapping during tachycardia identified different types of APs. (1) Seventeen patients had long APs originating from the right lateral atrium and coursing several centimeters to the right ventricle. In 10 patients, the AP terminated in or close to the right bundle-branch system (atriofascicular AP) and in 7, the AP terminated in the anterior right ventricle (atrioventricular AP). Patients with atriofascicular APs had narrower QRS complexes (133±10 versus 165±26 milliseconds,
P
=.02) and narrower initial r wave in leads V
2
through V
4
during maximal preexcitation than patients with atrioventricular APs. In addition, they had earlier His-bundle and right bundle-branch retrograde activation, ie, shorter V-His (16±5 versus 37±9 milliseconds,
P
<.01) and V–right bundle intervals (3±5 versus 25±6 milliseconds,
P
<.01). In 6 patients, minimal preexcitation not readily apparent was present in sinus rhythm despite the appearance of a narrow QRS complex. A wide distal insertion site of 0.5 to 2 cm in diameter consistent with arborization of the AP was found in 10 patients. The distal application of radiofrequency current produced a change in the preexcitation pattern in 4 patients and ablated the AP in 2 patients. In the other patients, radiofrequency current was applied more proximally and successfully ablated the AP bundle (n=9) or AP proximal insertion (n=6). No recurrence was observed during a follow-up period of 12±10 months. (2) Four patients had short paratricuspid atrioventricular APs; in one, the decremental conduction property was acquired as demonstrated by two electrophysiological studies performed 7 years apart. Radiofrequency ablation was successfully accomplished in all 4 patients at the tricuspid annulus.

Conclusions
Different types of APs account for tachycardias previously called Mahaim fibers. Long and short atrioventricular APs are observed in 81% and 19%, respectively. Long APs often have a distal arborization and may have either a fascicular or ventricular insertion. Radiofrequency current is more efficient when applied to the AP bundle or AP proximal insertion rather than to the distal insertion in patients with long APs.
Role of Calcium/Calmodulin-Dependent Protein Kinase II in the Regulation of Vascular Smooth Muscle Cell Migration
Authors: Pauly Rebecca R. , Bilato Claudio , Sollott Steven J. , Monticone Robert , Kelly Paul T. , Lakatta Edward G. , Crow Michael T.
Published: June 2012

Background
The migration of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of many vascular diseases. We have previously shown that VSMC migration in response to platelet-derived growth factor (PDGF) is suppressed when cultured cells are growth-arrested and induced to differentiate. The present study was undertaken to elucidate the mechanism of this suppression.

Methods and Results
While both proliferating and growth-arrested VSMCs upregulated expression of the immediate early response genes, c-
fos
and JE (monocyte chemoattractant protein 1), growth-arrested VSMCs exhibited much smaller changes in intracellular calcium in response to PDGF and failed to activate the calcium/calmodulin-dependent protein kinase II (CaM kinase II). Blocking calcium-calmodulin interactions (50 μmol/L W7) or the activation of CaM kinase II (10 μmol/L KN62) in proliferating cells blocked their migration by more than 90%, whereas inhibition of protein kinase C activation had no significant effect on migration. Pretreatment of growth-arrested VSMCs with the calcium ionophore ionomycin resulted in an approximately 2.5-fold activation of CaM kinase II and increased migration of growth-arrested cells to 84±6% that of proliferating cells. These effects of ionomycin were blocked by inhibitors of CaM kinase II. Constitutively activated (ie, calcium/calmodulin-independent) CaM kinase II introduced by gene transfection into growth-arrested cells significantly increased migration toward PDGF from <20% to >70% that of proliferating cells.

Conclusions
These results demonstrate that activation of CaM kinase II is required for VSMC migration, that its activation in response to PDGF is suppressed in growth-arrested VSMCs, and that this suppression of CaM kinase II activation is responsible, in large part, for the failure of growth-arrested VSMCs to migrate toward PDGF.
Fish Oil Treatment Decreases Superoxide Anions in the Myocardium and Coronary Arteries of Atherosclerotic Monkeys
Authors: Supari Fadilah , Ungerer Tonny , Harrison David G. , Williams J. Koudy
Published: June 2012

Background
This experiment sought to determine the effects of fish oil on superoxide anion production in the myocardium and coronary arteries of atherosclerotic monkeys. Recent evidence indicates that dietary supplementation with fish oil preserves normal vasomotion of atherosclerotic coronary arteries and reduces damage to the myocardium after ischemia and reperfusion, although the mechanisms remain unclear.

Methods and Results
Adult male cynomolgus monkeys were fed an atherogenic diet with (n=15) or without (n=15) half the fat calories from fish oil. After 12 months, chemiluminescence of lucigenin was used to measure superoxide anion production in coronary arteries and myocardium after 1 hour of ischemia and 2 hours of reperfusion. The signals were calibrated with known quantities of xanthine and xanthine oxidase. Superoxide anion production in ischemic myocardium was (mean±SEM, nmol/mg dry wt per minute) 1±1 and 4±1 in monkeys fed fish oil and not fed fish oil, respectively (
P
<.05). Superoxide anion production in coronary arteries not exposed to ischemia and reperfusion was (nmol/mg dry wt per minute) 4±1 and 8±2 in monkeys fed fish oil and not fed fish oil, respectively (
P
<.05). Superoxide anion production in coronary arteries was (nmol/mg dry wt per minute) 5±2 and 16±3 in monkeys fed fish oil and not fed fish oil after ischemia and reperfusion, respectively (
P
<.05).

Conclusions
Dietary supplementation with fish oil reduced vascular superoxide anion production and prevented the increase in vascular and myocardial superoxide anion production that accompanied ischemia and reperfusion. These phenomena may underlie some of the beneficial cardiovascular effects of fish oil.
Opposing Effects of Plasma Epinephrine and Norepinephrine on Coronary Thrombosis In Vivo
Authors: Lin Huabao , Young David B.
Published: June 2012

Background
It is well known that plasma catecholamines and myocardial infarction have a close relation and that coronary artery thrombosis is a major cause of myocardial infarction. In addition, epinephrine is known to be a prothrombogenic agent in vivo. However, the role of the other major circulating catecholamine, norepinephrine, in the development of coronary thrombosis is somewhat uncertain, although the role of norepinephrine is often considered analogous to the role of epinephrine. Therefore, the present study was designed to investigate the effect of norepinephrine and its interaction with epinephrine on coronary thrombosis.

Methods and Results
To compare the effects of epinephrine and norepinephrine on coronary thrombosis, we analyzed the frequency of cyclic blood flow reductions (CFRs) in an anesthetized canine model of coronary thrombosis (n=25). Three experiments were used in the present study. In the first experiment with epinephrine infusion, plasma epinephrine was elevated from 0.46±0.25 to 27.7±1.85 nmol/L. The frequency of CFRs increased by more than 60%, from 7.1±0.5 to 11.5±0.7 in 40 minutes (
P
<.01). The second experiment included three experimental periods: control, norepinephrine infusion, and norepinephrine infusion plus epinephrine infusion. Norepinephrine was infused to raise plasma norepinephrine from 1.3±0.2 to 32.4±4.3 nmol/L. The frequency of CFRs in the dogs was markedly reduced, from 7.89±0.42 to 2.41±1.08 in 40 minutes (
P
<.01), whereas arterial pressure was elevated from 88±3 to 118±5 mm Hg (
P
<.01). However, when epinephrine infusion was added to the norepinephrine infusion, the frequency of CFRs increased from 2.41±1.08 to 7.74±1.12 in 40 minutes (
P
<.01). In the third experiment, a servocontrol device was used during the norepinephrine infusion to prevent rises in coronary arterial pressure. As a result of the norepinephrine infusion, the frequency of CFRs was reduced from 7.47±0.71 to 0.83±0.65 in 40 minutes (
P
<.01), even though the coronary arterial pressure was not altered.

Conclusions
The present study demonstrated that infusion of epinephrine stimulated coronary artery thrombosis, whereas infusion of norepinephrine inhibited coronary artery thrombosis. In addition, the inhibitory effect of norepinephrine on coronary thrombosis is independent of increases in coronary arterial pressure. Therefore, the present findings suggest that epinephrine and norepinephrine have opposing effects on coronary thrombosis in dogs.
Effect of Coronary Artery Reperfusion on Transmural Myocardial Remodeling in Dogs
Authors: Ono Shiro , Waldman Lewis K. , Yamashita Hirohisa , Covell James W. , Ross John
Published: June 2012

Background
The effects of reperfusion after coronary occlusion on transmural remodeling of the ischemic region early and late after nontransmural infarction must importantly affect the recovery of regional function. Accordingly, analysis of local volume and three-dimensional strain was performed using a finite element method to determine regional remodeling. Systolic and remodeling strains were measured using radiographic imaging of three columns (≈1 cm apart) of four to six gold beads implanted across the left ventricular posterior wall in 6 dogs.

Methods and Results
After a control study, infarction was produced by 2 to 4 hours of proximal left circumflex coronary artery occlusion followed by reperfusion. Follow-up studies were performed at 2 days, 3 weeks, and 12 weeks with the dogs under anesthesia and in closed-chest conditions. Biplane cineradiography was performed to obtain the three-dimensional coordinates of the beads. At 2 days, end-systolic strains were akinetic with loss of normal transmural gradients of shortening and thickening. Remodeling strains (RS) were determined by use of a nonhomogeneous finite element method by referring the end-diastolic configuration during follow-up studies to its control state at matched end-diastolic pressures and heart rates. Tissue volume at 2 days increased substantially, more at the endocardium (30±7%) than at the epicardium (5±12%,
P
<.01); the increase was associated with an average RS in the wall-thickening direction of 0.18±0.15 (
P
<.01) with all other RS near zero. At 12 weeks systolic function partially recovered, with normal wall thickening in the epicardium (radial strain, 0.081±0.056 [control] versus 0.113±0.088 [12 weeks]) but with dysfunction in the endocardium (0.245±0.108 [control] versus 0.111±0.074 [
P
<.01] [12 weeks]). This inability of the inner wall to recover function may be related to increased transmural torsional shear and negative longitudinal-radial transverse shear in the inner wall. Volume loss occurred at 12 weeks in the endocardium (−36±16%) corresponding to transmural gradients in longitudinal RS and both transverse shear RS. Negative longitudinal RS was greater at the endocardium (−0.20±0.10) than at the epicardium (−0.06±0.05,
P
<.01).

Conclusions
These results indicate the presence of marked subendocardial edema 2 days after reperfusion following 2 to 4 hours of coronary occlusion. At 3 months after reperfusion, however, there was volume loss in the inner wall due to shrinkage along the myofiber direction with reduced transmural function and loss of longitudinal shortening, while both tissue volume and function recovered completely in the outer wall.
Comparative Real-Time Effects on Platelet Adhesion and Aggregation Under Flowing Conditions of In Vivo Aspirin, Heparin, and Monoclonal Antibody Fragment Against Glycoprotein IIb-IIIa
Authors: Turner Nancy A. , Moake Joel L. , Kamat Suraj G. , Schafer Andrew I. , Kleiman Neal S. , Jordan Robert , McIntire Larry V.
Published: June 2012

Background
A real-time in vitro system of human platelet thrombosis under arterylike flowing conditions similar to those produced in vivo by angioplasty would be useful for the evaluation of potential antiarterial thrombotic agents in association with in vivo trials. Aspirin, heparin, and the chimeric monoclonal antibody antigen-binding fragment 7E3 (c7E3 Fab) directed against platelet glycoprotein (GP) IIb-IIIa have been used in attempts to delay or prevent thrombotic reocclusion of coronary arteries after angioplasty. We compared the effects of these agents administered in vivo on GPIb-mediated platelet adhesion to von Willebrand factor (vWF)/collagen type I (as in atherosclerotic subendothelium) and on subsequent GPIIb-IIIa–fibrinogen/vWF–mediated platelet aggregation under flowing conditions analogous to those in constricted coronary arteries.

Methods and Results
Citrated whole blood containing mepacrine-labeled platelets from patients and healthy donors was perfused for 1 minute at an abnormally elevated shear rate of 1500 seconds
−1
(arterial wall shear stress of 50 to 60 dynes/cm
2
) at 37°C over collagen I/vWF. The number of adherent fluorescent platelets was quantified every 15 seconds with a low-light-level video camera and epifluorescent microscopy. After 5 healthy donors had ingested 975 mg aspirin, platelet adhesion was unaffected in the aspirin-treated blood compared with the control blood in all experiments (10 of 10), and subsequent aggregation was unchanged in most runs (8 of 10). The blood of 3 aspirin-treated patients undergoing angioplasty was analyzed before and after a 12 000-U heparin injection and 2 minutes, 2 hours, and 24 hours after infusion of 0.25 mg/kg of c7E3 Fab. In these patients, the bolus of heparin did not inhibit either platelet adhesion to collagen I/vWF or subsequent aggregation. In contrast, there was >50% inhibition of platelet aggregation 2 minutes after the infusion of c7E3 Fab in all 3 patients, and inhibition persisted in 2 of the 3 patients at 2 hours and 24 hours after c7E3 Fab.

Conclusions
In contrast to aspirin or heparin, the in vivo injection of c7E3 Fab considerably reduces platelet aggregate formation mediated by the binding of fibrinogen, vWF, or some other ligand to platelet GPIIb-IIIa under conditions of abnormally increased shear stress analogous to those in narrowed coronary arteries. Platelet adherence to collagen I/vWF is not affected. This study describes an in vitro model of arterial injury (similar to angioplasty) that uses human blood to compare directly, in real time, the precise relative effects of aspirin, heparin, and c7E3 Fab on platelet adhesion and subsequent aggregation.
Increased Serum Concentrations of Procollagen Peptides in Essential Hypertension
Authors: Díez Javier , Laviades Concepción , Mayor Gaspar , Gil María Jesús , Monreal Ignacio
Published: June 2012

Background
The serum concentrations of two procollagen-derived peptides, procollagen type III amino terminal peptide (PIIIP) and procollagen type I carboxy terminal peptide (PIP), have been proposed as useful markers of the tissue synthesis of collagen type III and type I, respectively. Therefore, this study was designed to evaluate fibrogenic activity in patients with essential hypertension by measuring serum PIIIP and PIP. Furthermore, since hypertensive heart disease is characterized by myocardial accumulation of collagen type III and type I, a second aim of the study was to assess whether some relation exists between the serum concentrations of PIIIP and PIP and several parameters of left ventricular anatomy and function in hypertensive patients.

Methods and Results
The study was performed in 50 patients with never-treated essential hypertension and in 30 normotensive control subjects. Measurements were repeated in 43 hypertensive patients after 6 months of treatment with the angiotensin-converting enzyme inhibitor lisinopril. The serum concentrations of PIIIP and PIP were measured by specific radioimmunoassay. Two-dimensional, targeted M-mode and Doppler ultrasound recordings were obtained in every subject to determine several parameters of the left ventricle anatomy and function. Ambulatory ECG monitoring was performed in each patient, and the recorded ventricular arrhythmias were categorized according to Lown-Wolf classification. Baseline serum PIIIP and PIP were increased (
P
<.001) in hypertensive patients as compared with normotensive subjects. An inverse correlation was found between serum PIIIP and the ratio between maximal early transmitral flow velocity and maximal late transmitral flow velocity measured during diastole (
r
=−.3786,
P
<.01) in the group of hypertensive patients. Serum PIP was correlated directly with the left ventricular mass index (
r
=.3277,
P
<.05) in the group of hypertensive patients. Serum PIP concentrations increased in parallel with the increase in the grade of ventricular arrhythmias in the group of hypertensive patients. Treated patients attained normalization in blood pressure, amelioration of diastolic filling, regression of left ventricular mass index, and a diminution in the number of daily ventricular extrasystoles. In addition, serum PIIIP and PIP concentrations decreased significantly (
P
<.001) to normal values in patients treated with lisinopril.

Conclusions
These findings suggest that tissue synthesis of collagen type III and type I is abnormally increased in essential hypertension and can be normalized by treatment with lisinopril. On the other hand, our results suggest that serum PIIIP and PIP are related to several anatomic and functional alterations of the hypertensive left ventricle. Serum procollagen peptide measurements may therefore provide indirect diagnostic information on the myocardial fibrosis associated with arterial hypertension.
Regulation, Chamber Localization, and Subtype Distribution of Angiotensin II Receptors in Human Hearts
Authors: Regitz-Zagrosek V. , Friedel N. , Heymann A. , Bauer P. , Neuß M. , Rolfs A. , Steffen C. , Hildebrandt A. , Hetzer R. , Fleck E.
Published: June 2012

Background
To assess the chamber localization, subtype distribution, and regulation of human myocardial angiotensin II receptors in heart failure, we determined the binding of angiotensin II, Sar
1
Ile
8
–angiotensin II, and the subtype-specific antagonists Dup 753 (AT1-specific) and PD 123319 (AT2-specific) in atria from patients with normal (left ventricular ejection fraction >55%) or moderately impaired (left ventricular ejection fraction 30% to 55%) cardiac function and in atria and ventricles from explanted end-stage failing hearts. Sarcolemmal and combined fractions, the latter including internalized receptors, were studied. In addition, AT1 mRNA content was analyzed by polymerase chain reaction after reverse transcription.

Methods and Results
The number of angiotensin II binding sites (B
max
) in sarcolemmal fractions was significantly reduced in explanted end-stage failing hearts in comparison with control subjects and moderate heart failure (B
max
3.9±0.8 versus 11.2±1.7 and 9.6±0.8 fmol/mg protein, respectively). A comparable 65% reduction in receptor numbers was found in combined fractions from end-stage failing hearts, indicating that the loss of binding sites was not due to their internalization. The dissociation constants were comparable in sarcolemmal and combined fractions and in nonfailing and failing hearts, ranging from 0.5±0.2 to 1.2±0.5 nmol/L. In nonfailing hearts, 69±4% of binding sites were blocked by the subtype-2–specific inhibitor PD 123319 and were therefore classified as AT2; 33±5% were blocked by the subtype-1–specific inhibitor DUP 753 and thus classified as subtype 1. In explanted hearts, comparable ratios of 66±5% AT2 sites and 34±5% AT1 sites were found. AT1 cDNA amplification signals by polymerase chain reaction were reduced to about one third of the level in control subjects in end-stage failing hearts.

Conclusions
Angiotensin II receptors in human myocardium are present in relatively low numbers, and AT2 is the predominant subtype. A significant loss of angiotensin II receptors occurs in end stage but not in moderate heart failure. The loss of receptors affects both subtypes to a comparable degree. The data suggest that the decrease in receptor density is due to a decrease in steady-state mRNA abundance.
Hypoxic Stress Induces Cardiac Myocyte–Derived Interleukin-6
Authors: Yamauchi-Takihara Keiko , Ihara Yoshiji , Ogata Atsushi , Yoshizaki Kazuyuki , Azuma Junichi , Kishimoto Tadamitsu
Published: June 2012

Background
Hypoxic and ischemic stresses cause a series of well-documented changes in myocardial cells and tissues, including loss of contractility, changes in lipid and fatty acid metabolism, and irreversible membrane damage leading to eventual cellular death. Activated neutrophils are considered to be involved in this myocardial cellular injury. By stimulation of the neutrophils with chemotactic factors, canine neutrophils can be induced to adhere to isolated cardiac myocytes only if the myocytes have been previously exposed to cytokines such as tumor necrosis factor–α, interleukin (IL)-1, and IL-6.

Methods and Results
To examine the possible involvement of IL-6 in ischemia-reperfusion injury, we used cultured rat neonatal cardiac myocytes to study the effects of hypoxic stress on the production of IL-6 by cardiac myocytes. Unstimulated cardiac myocytes (3×10
5
cells per dish) produced 320 pg IL-6 over 4 hours in vitro (ie, biological activity equal to 320 pg recombinant IL-6, as detected by bioassay using the MH-60.BSF2 cell line). The incubation of cardiac myocytes under hypoxic conditions for 4 hours induced significantly increased production of IL-6 compared with normoxic conditions (2.82±0.49 versus 1.64±0.18 U/mL,
P
<.05). Furthermore, reoxygenation for 2 hours after 2 hours of hypoxic stress significantly augmented the production of IL-6 by cardiac myocytes (4.34±0.52 U/mL,
P
<.05). These responses to hypoxia and reoxygenation were not observed in fibroblasts isolated from the same tissue. Although unstimulated cardiac myocytes lacked IL-6 mRNA expression detectable by Northern blot analysis, hypoxic stress induced the expression of IL-6 mRNA in the cardiac myocytes. Several pathophysiologically relevant factors also augmented IL-6 release from cultured cardiac myocytes, including IL-1β, ionomycin, and epinephrine.

Conclusions
Cardiac myocytes respond to hypoxic stress to augment the production of IL-6, and the IL-6 derived from cardiac myocytes may play an important role in the progression of myocardial dysfunction observed in cardiac ischemia-reperfusion injury.
Effect of β-Adrenergic Receptor Blockade on Blood Flow to Collateral-Dependent Myocardium During Exercise
Authors: Traverse Jay H. , Altman John D. , Kinn James , Duncker Dirk J. , Bache Robert J.
Published: June 2012

Background
β-Adrenergic receptors have been identified in isolated coronary collateral blood vessels, but their functional significance in the intact heart has not been demonstrated.

Methods and Results
We measured myocardial blood flow with radioactive microspheres in normal and collateral-dependent myocardium in eight dogs trained to run on a treadmill before and after β-adrenergic blockade with propranolol, 200 μg/kg, a dose that effectively inhibited the increase in coronary blood flow produced by selective β
1
- and β
2
-adrenergic agonists. Collateral vessel growth was stimulated with 2-minute intermittent occlusions of the left anterior descending artery followed by permanent occlusion. During control exercise, blood flow in the collateral zone was 38±5% less than in the normal zone. At identical levels of exercise, with heart rate maintained constant by atrial pacing, propranolol decreased mean blood flow in the collateralized myocardium from 1.93±0.17 to 1.50±0.14 mL · min
−1
· g
−1
(
P
<.01), while increasing the subendocardial to subepicardial blood flow ratio from 0.78±0.11 to 0.91±0.10 (
P
<.05). The decrease in collateral zone blood flow in response to propranolol resulted from an increase in both transcollateral resistance from 25.9±2.3 to 35.2±4.3 mm Hg · mL
−1
· min · g (
P
<.05) and small-vessel resistance in the collateral-dependent myocardium from 30.9±4.7 to 44.0±8.8 mm Hg · mL
−1
· min · g (
P
<.07). Blood flow to the normal zone was also significantly reduced from 3.14±0.21 to 2.23±0.12 mL · min
−1
· g
−1
(
P
<.01) after propranolol.

Conclusions
β-Adrenergic blockade decreased blood flow to collateral-dependent myocardium during exercise. These results indicate that β-adrenergic receptor activation contributes to vasodilation of coronary collateral vessels during exercise.
Cholesterol Derivative of a New Triantennary Cluster Galactoside Lowers Serum Cholesterol Levels and Enhances Secretion of Bile Acids in the Rat
Authors: Biessen Erik A.L. , Vietsch Helene , Van Berkel Theo J.C.
Published: June 2012

Background
Previous studies have demonstrated that cholesterol-derivatized galactosides exert a hypocholesterolemic effect by inducing hepatic uptake of atherogenic lipoproteins by means of galactose-recognizing receptors in the liver. However, a prolonged infusion of high concentrations of these compounds was required for this effect, possibly because of low affinity for the galactose-recognizing asialoglycoprotein receptor on the parenchymal liver cell.

Methods and Results
We have designed a new series of triantennary galactosides to optimize the affinity and specificity for this receptor. The affinity of a triantennary galactoside for the asialoglycoprotein receptor appeared to be dramatically enhanced by proper spacing of the three terminal galactose groups. In rats, a single injection of
N
-[tris-
O
-(3,6,9-trioxaundecanyl-β-
d
-galactopyranosyl)methoxymethyl]methyl-
N
α
-[1-(6-(5-cholesten-3β-yloxy)glycyl)adipyl]glycinamide [TG(20Å)C], the cholesterol derivative of the most selective galactoside, causes a dose-dependent decrease of ≤45% in the serum cholesterol concentration (
P
<.001). This decrease is mainly attributed to a decrease in the level of serum HDL (
P
=.0066) and, to a lesser extent, serum LDL (
P
=.036). In addition, TG(20Å)C strongly enhances the bile-acid secretion in rats during the first 2 hours after administration, which indicates that TG(20Å)C-induced clearance of cholesterol from the bloodstream is efficiently coupled to hepatic bile-acid secretion.

Conclusions
We conclude that TG(20Å)C efficiently directs lipoproteins that contain cholesterol to the liver at a 30-fold-lower concentration than previously developed cholesterol-derivatized cluster galactosides. This newly developed approach to lower cholesterol levels may prove valuable for familial hypercholesterolemic patients or those with familial defective apolipoprotein B-100 who do not respond or who respond insufficiently, respectively, to conventional therapies.
The Role of Neutral Endopeptidase in Dogs With Evolving Congestive Heart Failure
Authors: Margulies Kenneth B. , Barclay Paul L. , Burnett John C.
Published: June 2012

Background
Recent studies suggest that neurohumoral mechanisms including decreased renal responses to increases in atrial natriuretic factor (ANF) play a central role in the progression from asymptomatic cardiac dysfunction to advanced congestive heart failure (CHF) with sodium retention, vasoconstriction, and reduced exercise tolerance. Recognizing that neutral endopeptidase 24.11 degrades ANF and may be enhanced in CHF, we hypothesized that chronic neutral endopeptidase inhibition (NEP-I) would potentiate renal responses to exogenous ANF and alter the temporal evolution of sodium retention in evolving CHF by potentiation of increased endogenous ANF.

Methods and Results
We studied 13 conscious dogs with evolving CHF produced by rapid ventricular pacing at 250 beats per minute. Six of these dogs received NEP-I with candoxatril, 10 mg/kg PO BID, throughout evolving CHF. Responses to exogenous ANF, 10 μg/kg IV bolus, were assessed at baseline and after 6 days of CHF. Daily metabolic studies during evolving CHF with chronic NEP-I showed increased sodium excretion and renal cGMP generation consistent with enhanced renal activity of endogenous ANF compared with untreated controls. In addition, renal natriuretic and cGMP responses to exogenous ANF were intact in CHF with chronic NEP-I in contrast to markedly attenuated renal responses to exogenous ANF in untreated CHF. Despite enhanced ANF responsiveness and improved sodium balance in evolving CHF, a moderate degree of sodium retention was observed during chronic NEP-I in evolving CHF.

Conclusions
Enzymatic degradation by neutral endopeptidase limits local renal responses to increases in endogenous and exogenous ANF in CHF independent of changes in systemic hemodynamics or augmented plasma concentrations of ANF. The moderate sodium retention observed during evolving CHF despite chronic NEP-I probably reflects the antinatriuretic effects of hemodynamic and humoral factors independent of ANF activity.
Angiotensin-Converting Enzyme Gene Polymorphism Is Associated With Myocardial Infarction but Not With Development of Coronary Stenosis
Authors: Ludwig Erwin , Corneli Patrice S. , Anderson Jeffrey L. , Marshall Hiram W. , Lalouel Jean-Marc , Ward R. H.
Published: June 2012

Background
Although both genetic and nongenetic factors contribute to the pathogenesis of coronary artery disease, the identification of specific genetic lesions has lagged behind the identification of critical environmental risk factors. A reported association between myocardial infarction (MI) and the insertion/deletion
(I/D)
polymorphism of the angiotensin-converting enzyme
(ACE)
gene in European men suggests a critical role for this genomic region. However, the generality of this association remains to be determined. It also is not clear at what stage in disease progression the association with the
ACE I/D
polymorphism becomes important.

Methods and Results
We evaluated the
ACE I/D
polymorphism in patients who had undergone coronary angiography (402 men and 295 women) and in 203 representative control subjects. After polymerase chain reaction amplification, genotypes were determined by agarose gel sizing and by hybridization with allele-specific oligonucleotides. After patients were categorized by the degree of coronary artery stenosis and the occurrence of an MI, the distribution of
ACE I/D
genotypes was evaluated by log linear analysis. Patients were genetically representative of the regional population, and patients with >60% stenosis of their coronary arteries had the same distribution of
ACE I/D
genotypes as did patients with <10% stenosis. However, among patients with stenosis, the occurrence of an MI was significantly associated with the
D
allele in all patients (odds ratio [OR], 1.59;
P
=.002) and in men alone (OR, 1.63;
P
=.006). The lack of significance in women (OR, 1.40;
P
=.263) is probably due to the fact that only 36 women in the present study had experienced an MI. Furthermore, the association between MI and the
ACE I/D
polymorphism was independent of blood pressure, smoking habits, and body mass index.

Conclusions
Segregation of the
ACE I/D
polymorphism is a pervasive genetic risk factor for MI in whites but has no evident effect on the events leading to stenosis of the coronary arteries. This suggests that risk of MI is influenced by two independent processes—atherogenesis that leads to coronary stenosis followed by conversion to MI. The renin-angiotensin system appears to confer significant risk of infarction by influencing the conversion to MI but has no apparent effect on the development of atherostenosis.
Randomized Study of Implantable Defibrillator as First-Choice Therapy Versus Conventional Strategy in Postinfarct Sudden Death Survivors
Authors: Wever Eric F.D. , Hauer Richard N.W. , van Capelle Frans J.L. , Tijssen Jan G.P. , Crijns Harry J.G.M. , Algra Ale , Wiesfeld Ans C.P. , Bakker Patricia F.A. , Robles de Medina Etienne O.
Published: June 2012

Background
In retrospective studies of sudden cardiac death survivors, the implantable cardioverter-defibrillator (ICD) compares favorably with medical and surgical therapy. Thus, use of the conventional strategy of starting treatment with antiarrhythmic drugs (AD), at least in certain patient categories, may be questionable. The goal of this study was to analyze the effectiveness of ICD implantation as first-choice therapy versus the conventional therapeutic strategy of starting with AD.

Methods and Results
Sixty consecutive survivors of cardiac arrest caused by old myocardial infarction were randomly assigned early ICD implantation (n=29) or conventional therapy (n=31). Baseline characteristics were similar in the two groups. Therapy in each patient was always guided by ECG monitoring, exercise testing, and programmed electrical stimulation (PES). Primary end points (main outcome events, including death, recurrent cardiac arrest, and cardiac transplantation), number of invasive procedures and antiarrhythmic therapy changes, and duration of hospitalization were compared. Median follow-up was 24 months (mean, 27 months). In the early ICD group, 4 patients (14%) died, all of cardiac causes. In the conventional group, 20 patients failed AD and subsequently underwent map-guided ventricular tachycardia (VT) surgery (6 patients) or ICD implantation (14 patients). Of the 6 VT surgery patients, 1 died, 1 had cardiac transplantation, and 1 had an ICD implantation because of persistent inducibility despite the addition of AD. Of the 11 patients who remained on AD as sole therapy, 2 died in the hospital before they could be retested by PES, leaving 9, judged adequately protected by AD alone. Of those, 5 died, and 1 survived recurrent cardiac arrest followed by ICD implantation. In total, 16 conventionally treated patients ended up with late ICD implantation, 3 of whom died. Thus, total mortality in the conventional group was 11 patients (35%): 4 died suddenly, 5 died of heart failure, and 2 died of noncardiac causes. Comparison of the main outcome events in both strategies showed a significant difference in favor of early ICD implantation (hazard ratio, 0.27; 95% CI, 0.09 to 0.85;
P
=.02). In addition, the early ICD group underwent fewer invasive procedures (median, 1 versus 3;
P
<.0001), had less therapy changes (
P
<.0001), and spent fewer days in hospital (median, 34 versus 49;
P
=.02).

Conclusions
These data suggest that ICD implantation as first choice is preferable to the conventional approach in survivors of cardiac arrest caused by old myocardial infarction. Conventionally treated patients are likely to end up with an ICD, and those who remain on AD as sole therapy have a high risk of death regardless of efficacy assessment, including PES. .
Normalization of Diastolic Dysfunction in Aortic Stenosis Late After Valve Replacement
Authors: Villari Bruno , Vassalli Giuseppe , Monrad E. Scott , Chiariello Massimo , Turina Marko , Hess Otto M.
Published: June 2012

Background
The remodeling of the left ventricle in patients with aortic stenosis after aortic valve replacement (AVR) is a complex process involving structural and functional changes.

Methods and Results
Twenty-two patients were included in the present analysis. Twelve patients with severe aortic stenosis were studied before surgery, early (22±8 months) and late (81±22 months) after AVR using left ventricular biplane angiograms, high-fidelity pressure measurements, and endomyocardial biopsies. Ten healthy subjects were used as controls. Left ventricular systolic function was assessed from biplane ejection fraction, and diastolic function from the time constant of relaxation, the peak filling rate, and the myocardial stiffness constant. Left ventricular structure was evaluated from interstitial fibrosis, fibrous content, and muscle fiber diameter. Left ventricular muscle mass was significantly increased before surgery in patients with aortic stenosis and remained increased early after surgery, although there was a 35% decrease. Late after AVR, muscle mass decreased significantly but remained slightly (
P
=NS) elevated. Left ventricular ejection fraction increased slightly after AVR. Left ventricular relaxation was significantly prolonged before surgery and returned toward normal early and late after AVR. Peak filling rates remained unchanged before and after surgery. Myocardial stiffness constant was increased before surgery in patients with aortic stenosis compared with controls and increased even further early after AVR but was normalized late after surgery. Muscle fiber diameter was elevated in patients with aortic stenosis before and after surgery compared with controls; however, it decreased significantly early and late after AVR with respect to preoperative data but remained hypertrophied even late after surgery. Interstitial fibrosis and fibrous contents were larger before surgery than in control subjects and increased even more early but decreased significantly late after AVR.

Conclusions
Diastolic stiffness increases in aortic stenosis early after AVR parallel to the increase in interstitial fibrosis, whereas relaxation rate decreases with a reduction in left ventricular muscle mass. Late after AVR, both diastolic stiffness and relaxation are normalized due to the regression of both muscular and nonmuscular tissue. Thus, reversal of diastolic dysfunction in aortic stenosis takes years and is accompanied by a slow regression of interstitial fibrosis.