bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeted Anticytokine Therapy in Patients With Chronic Heart Failure
Authors: Mann Douglas L. , McMurray John J.V. , Packer Milton , Swedberg Karl , Borer Jeffrey S. , Colucci Wilson S. , Djian Jacques , Drexler Helmut , Feldman Arthur , Kober Lars , Krum Henry , Liu Peter , Nieminen Markku , Tavazzi Luigi , van Veldhuisen Dirk Jan , Waldenstrom Anders , Warren Marshelle , Westheim Arne , Zannad Faiez , Fleming Thomas
Published: March 2004

Background—

Studies in experimental models and preliminary clinical experience suggested a possible therapeutic role for the soluble tumor necrosis factor antagonist etanercept in heart failure.

Methods and Results—

Patients with New York Heart Association class II to IV chronic heart failure and a left ventricular ejection fraction ≤0.30 were enrolled in 2 clinical trials that differed only in the doses of etanercept used. In RECOVER, patients received placebo (n=373) or subcutaneous etanercept in doses of 25 mg every week (n=375) or 25 mg twice per week (n=375). In RENAISSANCE, patients received placebo (n=309), etanercept 25 mg twice per week (n=308), or etanercept 25 mg 3 times per week (n=308). The primary end point of each individual trial was clinical status at 24 weeks. Analysis of the effect of the 2 higher doses of etanercept on the combined outcome of death or hospitalization due to chronic heart failure from the 2 studies was also planned (RENEWAL). On the basis of prespecified stopping rules, both trials were terminated prematurely owing to lack of benefit. Etanercept had no effect on clinical status in RENAISSANCE (
P
=0.17) or RECOVER (
P
=0.34) and had no effect on the death or chronic heart failure hospitalization end point in RENEWAL (etanercept to placebo relative risk=1.1, 95% CI 0.91 to 1.33,
P
=0.33).

Conclusions—

The results of RENEWAL rule out a clinically relevant benefit of etanercept on the rate of death or hospitalization due to chronic heart failure.
Atorvastatin Does Not Affect the Antiplatelet Potency of Clopidogrel When It Is Administered Concomitantly for 5 Weeks in Patients With Acute Coronary Syndromes
Authors: Mitsios John V. , Papathanasiou Athanasios I. , Rodis Foteini I. , Elisaf Moses , Goudevenos John A. , Tselepis Alexandros D.
Published: March 2004

Background—

The antiplatelet effect of clopidogrel may be attenuated by short-term coadministration of lipophilic statins. We investigated whether the coadministration of atorvastatin for 5 weeks in patients with acute coronary syndromes (ACS) could affect the antiplatelet potency of clopidogrel.

Methods and Results—

Forty-five hypercholesterolemic patients with the first episode of an ACS were included in the study. Patients were randomized to receive daily either 10 mg of atorvastatin (n=21) or 40 mg of pravastatin (n=24). Thirty patients who underwent percutaneous coronary intervention (PCI) received a loading dose of 375 mg of clopidogrel, followed by 75 mg/d for at least 3 months. In the remaining 15 patients who refused to undergo PCI, clopidogrel therapy was not administered. Eight normolipidemic patients with the first episode of an ACS were also included and received only clopidogrel. The serum levels of soluble CD40L and the adenosine 5′-diphosphate– or thrombin receptor activating peptide-14–induced platelet aggregation, as well as P-selectin and CD40L surface expression, were studied at baseline (within 30 minutes after admission) and 5 weeks later. Neither atorvastatin nor pravastatin significantly influenced the clopidogrel-induced inhibition of platelet activation, nor did clopidogrel influence the therapeutic efficacy of atorvastatin.

Conclusions—

Atorvastatin does not affect the antiplatelet potency of clopidogrel when coadministered for 5 weeks in ACS patients.
Pregnancy-Associated Plasma Protein A and Its Endogenous Inhibitor, the Proform of Eosinophil Major Basic Protein (proMBP), Are Related to Complex Stenosis Morphology in Patients With Stable Angina Pectoris
Authors: Cosin-Sales Juan , Christiansen Michael , Kaminski Paul , Oxvig Claus , Overgaard Michael T. , Cole Della , Holt David W. , Kaski Juan Carlos
Published: March 2004

Background—

The metalloproteinase pregnancy-associated plasma protein-A (PAPP-A) has been implicated in coronary plaque disruption. Its endogenous inhibitor, the proform of eosinophil major basic protein (proMBP), may also play a role in this process. Atheromatous plaque disruption often presents as complex angiographic lesions. We sought to assess whether PAPP-A, proMBP, and PAPP-A/ProMBP ratio are markers of angiographic plaque complexity in patients with chronic stable angina.

Methods and Results—

We studied 396 stable angina patients (age 63±10 years, 230 men) of whom 289 had angiographically documented coronary artery disease (≥75% stenosis). All coronary stenoses ≥30% diameter reduction (n =531 in 322 patients) were assessed and classified as complex (n =228) or smooth (n =303) by previously validated criteria. PAPP-A, proMBP, and C-reactive protein (hs-CRP) serum levels were measured by ELISA. Patients with complex coronary stenoses had a significantly (
P
<0.001) higher PAPP-A/proMBP ratio (3.1±1.2 versus 2.7±0.8×10
−3
) and PAPP-A levels (5.9±1.6 versus 5.1±1.4 mIU/L) than those without. On univariate analysis, male gender (
P
<0.001), age (
P
<0.001), previous history of myocardial infarction (
P
=0.013), reduced ejection fraction (
P
<0.001), severe coronary artery disease (
P
<0.001), aspirin treatment (
P
<0.001), PAPP-A levels (
P
<0.001), and PAPP-A/proMBP ratio (
P
<0.001) were correlated with the number of complex stenoses. Multiple regression analysis showed that male gender, age, severe coronary artery disease, and PAPP-A/proMBP ratio were independent predictors of the number of angiographically complex stenoses.

Conclusions—

In patients with stable angina, PAPP-A and PAPP-A/proMBP ratio are associated with angiographic plaque complexity.
Public Access Defibrillation in Out-of-Hospital Cardiac Arrest
Authors: Culley Linda L. , Rea Thomas D. , Murray John A. , Welles Barbara , Fahrenbruch Carol E. , Olsufka Michele , Eisenberg Mickey S. , Copass Michael K.
Published: March 2004

Background—

The dissemination and use of automated external defibrillators (AEDs) beyond traditional emergency medical services (EMS) into the community has not been fully evaluated. We evaluated the frequency and outcome of non-EMS AED use in a community experience.

Methods and Results—

The investigation was a cohort study of out-of-hospital cardiac arrest cases due to underlying heart disease treated by public access defibrillation (PAD) between January 1, 1999, and December 31, 2002, in Seattle and surrounding King County, Washington. Public access defibrillation was defined as out-of-hospital cardiac arrest treated with AED application by persons outside traditional emergency medical services. The EMS of Seattle and King County developed a voluntary Community Responder AED Program and registry of PAD AEDs. During the 4 years, 475 AEDs were placed in a variety of settings, and more than 4000 persons were trained in cardiopulmonary resuscitation and AED operation. A total of 50 cases of out-of-hospital cardiac arrest were treated by PAD before EMS arrival, which represented 1.33% (50/3754) of all EMS-treated cardiac arrests. The proportion treated by PAD AED increased each year, from 0.82% in 1999 to 1.12% in 2000, 1.41% in 2001, and 2.05% in 2002 (
P
=0.019, test for trend). Half of the 50 persons treated with PAD survived to hospital discharge, with similar survival for nonmedical settings (45% [14/31]) and out-of-hospital medical settings (58% [11/19]).

Conclusions—

PAD was involved in only a small but increasing proportion of out-of-hospital cardiac arrests.
Characterization of Left Ventricular Diastolic Function by Tissue Doppler Imaging and Clinical Status in Children With Hypertrophic Cardiomyopathy
Authors: McMahon Colin J. , Nagueh Sherif F. , Pignatelli Ricardo H. , Denfield Susan W. , Dreyer William J. , Price Jack F. , Clunie Sarah , Bezold Louis I. , Hays Amanda L. , Towbin Jeffrey A. , Eidem Benjamin W.
Published: March 2004

Background—

Conventional transmitral Doppler indices are unreliable in assessing clinical status in patients with hypertrophic cardiomyopathy (HCM) because they are affected by loading conditions. This study sought to determine whether tissue Doppler velocities are predictive of adverse clinical outcomes including death, cardiac arrest, ventricular tachycardia (VT), significant cardiac symptoms, and exercise capacity in children with HCM.

Methods and Results—

We studied 80 consecutive children (median age 12 years, median follow-up 26 months) evaluated at 1 hospital from January 1999 to August 2003 compared with 80 age- and gender-matched controls. Patients underwent echocardiography, ambulatory Holter monitoring, and upright exercise testing. Children with HCM had significantly decreased early diastolic tissue Doppler velocities at the lateral mitral (13.2 versus 19.3 cm/s), tricuspid (13.3 versus 16.3 cm/s), and septal (9.4 versus 13.5 cm/s) annuli compared with controls (
P
<0.001 for each comparison). By forward stepwise regression analysis, early transmitral left ventricular filling velocity (E)/septal Ea ratio predicted death, cardiac arrest, or VT (
r
=0.610,
R
2
=0.37,
P
<0.001). Peak oxygen consumption (V̇
o
2
) was most predictive of children who developed symptoms (
r
=0.427,
R
2
=0.182,
P
<0.001). Peak V̇
o
2
correlated inversely with E/Ea septal ratio (
r
=−0.740,
P
<0.01).

Conclusions—

Transmitral E/septal Ea ratio predicts children with HCM who are at risk of adverse clinical outcomes including death, cardiac arrest, VT, and significant cardiac symptoms. Peak V̇
o
2
correlated with peak exercise capacity in HCM patients.
Endothelial Dysfunction and Increased Arterial Intima-Media Thickness in Children With Type 1 Diabetes
Authors: Järvisalo Mikko J. , Raitakari Maria , Toikka Jyri O. , Putto-Laurila Anne , Rontu Riikka , Laine Seppo , Lehtimäki Terho , Rönnemaa Tapani , Viikari Jorma , Raitakari Olli T.
Published: March 2004

Background—

Endothelial dysfunction may play a pathophysiological role in the development of atherosclerosis in subjects with type 1 diabetes. We examined whether alterations in vascular endothelial function exist in children with type 1 diabetes and tested the hypothesis that endothelial dysfunction is associated with early structural atherosclerotic vascular changes in these children.

Methods and Results—

Noninvasive ultrasound was used to measure brachial artery flow-mediated dilation (FMD) responses and carotid artery intima-media thickness (IMT) in 75 children (mean age 11±2 years), 45 with type 1 diabetes (diabetes duration 4.4±2.9 years) and 30 healthy control children. Children with diabetes had lower peak FMD response (4.4±3.4% versus 8.7±3.6%,
P
<0.001) and increased IMT (
P
<0.001) compared with controls. Sixteen children with diabetes (36%) had endothelial dysfunction defined as total FMD response in the lowest decile for normal children. These children had increased carotid IMT (0.58±0.05 versus 0.54±0.04 mm,
P
=0.01) and higher LDL cholesterol concentration (2.63±0.76 versus 2.16±0.60 mmol/L,
P
=0.03) compared with diabetic children without endothelial dysfunction. Multivariate correlates of increased IMT included diabetes group (
P
=0.03), low FMD (
P
=0.03), and high LDL cholesterol (
P
=0.08).

Conclusions—

Impaired FMD response is a common manifestation in children with type 1 diabetes and is associated with increased carotid artery IMT. These data suggest that endothelial dysfunction in children with type 1 diabetes may predispose them to the development of early atherosclerosis.
Initial Experience With Remote Catheter Ablation Using a Novel Magnetic Navigation System
Authors: Ernst Sabine , Ouyang Feifan , Linder Christian , Hertting Klaus , Stahl Fabian , Chun Julian , Hachiya Hitoshi , Bänsch Dietmar , Antz Matthias , Kuck Karl-Heinz
Published: March 2004

Background—

Catheters are typically stiff and incorporate a pull-wire mechanism to allow tip deflection. While standing at the patient’s side, the operator manually navigates the catheter in the heart using fluoroscopic guidance.

Methods and Results—

A total of 42 patients (32 female; mean age, 55±15 years) underwent ablation of common-type (slow/fast) or uncommon-type (slow/slow) atrioventricular nodal reentrant tachycardia (AVNRT) with the use of the magnetic navigation system Niobe (Stereotaxis, Inc). It consists of 2 computer-controlled permanent magnets located on opposite sides of the patient, which create a steerable external magnetic field (0.08 T). A small magnet embedded in the catheter tip causes the catheter to align and to be steered by the external magnetic field. A motor drive advances or retracts the catheter, enabling complete remote navigation. Radiofrequency current was applied with the use of a remote-controlled 4-mm, solid-tip, magnetic navigation–enabled catheter (55°C, maximum 40 W, 60 seconds) in all patients. The investigators, who were situated in the control room, performed the ablation using a mean of 7.2±4.7 radiofrequency current applications (mean fluoroscopy time, 8.9±6.2 minutes; procedure duration, 145±43 minutes). Slow pathway ablation was achieved in 15 patients, whereas slow pathway modulation was the end point in the remaining patients. There were no complications.

Conclusions—

The Niobe magnetic navigation system is a new platform technology allowing remote-controlled navigation of an ablation catheter. In conjunction with a motor drive unit, this system was used successfully to perform completely remote-controlled mapping and ablation in patients with AVNRT.
Simvastatin Prevents Load-Induced Protein Tyrosine Nitration in Overloaded Hearts
Authors: Nadruz Wilson , Lagosta Valquer Jose , Moreno Heitor , Coelho Otavio Rizzi , Franchini Kleber Gomes
Published: March 2004

Hydroxymethylglutaryl-coenzyme A reductase inhibitors prevent load-induced left ventricular hypertrophy (LVH). Whether this effect is related to antioxidant properties of this class of drugs is poorly understood. The aim of the present report was to evaluate the regulation of nitrotyrosine production during the development of load-induced LVH and the effect of simvastatin treatment in this process. Rats were subjected to aortic constriction up to 15 days. LVH was evaluated by left/right ventricle mass ratio. Myocardial content of nitrotyrosine, nitric oxide synthase (NOS) isoforms, and phagocyte-type NAD(P)H-oxidase subunits (p67-phox and p22-phox) were analyzed by immunoblotting and immunohistochemistry assays. Another group of rats received treatment with either simvastatin or placebo for 15 days after the onset of pressure overload, and their hearts were also studied. Myocardial nitrotyrosine content was increased from 3 to 15 days of pressure overload in regions of cardiac myocytes in close apposition to myocardial stroma during LVH. Neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS) isoforms had their expression increased in coronary vessels (nNOS and iNOS) and in myocardial stroma (eNOS) from day 3 to day 7 of aortic constriction. However, p67-phox and p22-phox expression was increased in cells of myocardial stroma in parallel to augmented myocardial nitrotyrosine content. Simvastatin treatment inhibited the increases in myocardial nitrotyrosine content and in p67-phox and p22-phox expression, and significantly reduced LVH. In conclusion, antioxidant properties of simvastatin might play a role in myocardial remodeling induced by pressure overload.
Insulin Resistance and Alterations in Angiogenesis
Authors: Thadhani Ravi , Ecker Jeffrey L. , Mutter Walter P. , Wolf Myles , Smirnakis Karen V. , Sukhatme Vikas P. , Levine Richard J. , Karumanchi S. Ananth
Published: March 2004

Altered angiogenesis and insulin resistance, which are intimately related at a molecular level, characterize preeclampsia. To test if an epidemiological interaction exists between these two alterations, we performed a nested case-control study of 28 women who developed preeclampsia and 57 contemporaneous controls. Serum samples at 12 weeks of gestation were measured for sex hormone binding globulin (SHBG; low levels correlate with insulin resistance) and placental growth factor (PlGF; a proangiogenic molecule). Compared with controls, women who developed preeclampsia had lower serum levels of SHBG (208±116 versus 256±101 nmol/L,
P
=0.05) and PlGF (16±14 versus 67±150 pg/mL,
P
<0.001), and in multivariable analysis, women with serum levels of PlGF ≤20 pg/mL had an increased risk of developing preeclampsia (odds ratio [OR] 7.6, 95% CI 1.4 to 38.4). Stratified by levels of serum SHBG (≤175 versus >175 mg/dL), women with low levels of SHBG and PlGF had a 25.5-fold increased risk of developing preeclampsia (
P
=0.10), compared with 1.8 (
P
=0.38) among women with high levels of SHBG and low levels of PlGF. Formal testing for interaction (PlGF×SHBG) was significant (
P
=0.02). In a model with 3 (n−1) interaction terms (high PlGF and high SHBG, reference), the risk for developing preeclampsia was as follows: low PlGF and low SHBG, OR 15.1, 95% CI 1.7 to 134.9; high PlGF and low SHBG, OR 4.1, 95% CI 0.45 to 38.2; low PlGF and high SHBG, OR 8.7, 95% CI 1.2 to 60.3. Altered angiogenesis and insulin resistance are additive insults that lead to preeclampsia.
Novel Mechanisms Responsible for Postmenopausal Hypertension
Authors: Reckelhoff Jane F. , Fortepiani Lourdes A.
Published: March 2004

Blood pressure increases in many women after menopause. Hypertension is one of the major risk factors for cardiovascular disease. However, the mechanisms responsible for the postmenopausal increase in blood pressure are yet to be elucidated. Various humoral systems have been proposed to play a role in postmenopausal hypertension, such as changes in estrogen/androgen ratios, increases in endothelin and oxidative stress, and activation of the renin-angiotensin system (RAS). In addition, obesity, type II diabetes, and activation of the sympathetic nervous system are common in postmenopausal women and may also play important roles. However, progress in elucidating the mechanisms responsible for postmenopausal hypertension has been hampered by the lack of a suitable animal model. The aging female spontaneously hypertensive rat (SHR) exhibits many of the characteristics found in postmenopausal women. In this review, some of the possible mechanisms that could play a role in postmenopausal hypertension are discussed, as well as the characteristics of the aged female SHR as a model to study.
Reduction of Cardiac Fibrosis Decreases Systolic Performance Without Affecting Diastolic Function in Hypertensive Rats
Authors: Cingolani Oscar H. , Yang Xiao-Ping , Liu Yun-He , Villanueva Mirko , Rhaleb Nour-Eddine , Carretero Oscar A.
Published: March 2004

Pressure-overload left ventricular hypertrophy (LVH) is characterized by an increase in myocyte size and fibrosis. However, it is not clear how each of these components affects hypertensive heart disease (HHD). We have shown in 2 different rat models of hypertension that cardiac fibrosis can be reduced with
N
-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), an antifibrotic peptide normally present in mammals. To assess how inhibition of fibrosis affects HHD, spontaneously hypertensive rats (SHR) and normotensive controls (WKY) were treated with Ac-SDKP or vehicle. Cardiac systolic and diastolic function were assessed using in vivo pressure-volume (PV) analysis. Left ventricle passive compliance was also determined ex vivo. We found that in SHR, Ac-SDKP normalized left ventricle total collagen content and interstitial collagen fraction without changing myocyte diameter or left ventricle mass. In WKY, collagen did not change significantly after treatment. Ac-SDKP did not affect left ventricle diastolic function, determined in vivo and ex vivo in SHR and WKY, whereas systolic function was significantly decreased in SHR treated with Ac-SDKP and unchanged in treated WKY. We concluded that in adult SHR, reducing left ventricle collagen deposition with Ac-SDKP does not improve diastolic function, whereas it decreases systolic performance. These findings suggest that total left ventricle collagen reduction per se does not necessarily benefit cardiac function. In HHD, other factors besides collagen quantity, such as myocyte hypertrophy and/or collagen type or cross-link, might be targeted to improve cardiac function.
Diagnosis and Localization of Pheochromocytoma
Authors: Goldstein David S. , Eisenhofer Graeme , Flynn John A. , Wand Gary , Pacak Karel
Published: March 2004

This Hypertension Grand Rounds shows how applying new clinical laboratory techniques helped to diagnose pheochromocytoma in a difficult case. In the setting of long-standing, sustained hypertension, the patient had a hypertensive paroxysm during anesthesia induction for surgery, leading to suspicion of a pheochromocytoma. Conventional testing, including CT scanning and fractionated urinary metanephrine test, was not diagnostic. The patient had another hypertensive paroxysm during subsequent anesthesia induction, requiring intensive care. Consistently elevated plasma levels of free normetanephrine provided the first and only biochemical evidence for a pheochromocytoma in this case. 6-[
18
F]Fluorodopamine positron emission tomography and
123
I-metaiodobenzylguanidine scintigraphy subsequently agreed on the existence of a small left adrenal mass, which when removed surgically proved to be a pheochromocytoma. Postoperatively, plasma levels of normetanephrine normalized, and there were no further hypertensive paroxysms, although the patient remained hypertensive. This case illustrates the superiority of plasma levels of free (unconjugated) metanephrines, compared with other biochemical tests, to detect pheochromocytoma. It also confirms that functional imaging by 6-[
18
F]fluorodopamine or
123
I-metaiodobenzylguanidine scanning can localize pheochromocytoma in difficult cases in which other imaging tests are not diagnostic.
Integrating Drug Pharmacokinetics for Phenotyping Individual Renin Response to Angiotensin II Blockade in Humans
Authors: Azizi Michel , Bissery Alvine , Lamarre-Cliche Maxime , Ménard Joël
Published: March 2004

Renin release into plasma has been used to investigate the drug dose-dependence of renin-angiotensin system inhibition because it is proportional to the interruption of the permanent negative feedback loop of angiotensin II on renin secretion. We investigated the 24-hour between-subject differences in renin profiles by analyzing the time-dependence of individual renin responses in 16 mildly sodium-depleted normotensive subjects exposed in a 4-period crossover study to single oral doses of 8- and 16-mg (C8 and C16) candesartan cilexetil and 80- and 160-mg (V80 and V160) valsartan. C8 had a similar effect to V160 in terms of the increase in active renin concentration and decrease in blood pressure. C16 had the strongest effect and V80 the weakest effect on renin release. Within- and between-subject variability was more marked for valsartan pharmacokinetics than for candesartan pharmacokinetics and influenced variability in renin response. To eliminate some of the variability caused by the pharmacokinetics of each drug, we corrected the area under time curve of plasma renin levels by that of plasma drug levels to obtain an individual normalized index of renin release or “renin/pharmacokinetic index”. In these experimental conditions, this index was found to be a reproducible individual characteristic affecting renin response, in addition to the pharmacokinetics and pharmacological properties of angiotensin II type-1 receptor antagonists. The pharmacokinetic–pharmacodynamic model of renin release described here could be of value for the identification and investigation of renin release abnormalities in patients with hypertension and for the comparison of renin-angiotensin system blockers.
Myocardin and Prx1 Contribute to Angiotensin II-Induced Expression of Smooth Muscle α-Actin
Authors: Yoshida Tadashi , Hoofnagle Mark H. , Owens Gary K.
Published: March 2004

Previous studies demonstrated that angiotensin II (Ang II)-induced hypertrophy of smooth muscle cells (SMCs) was associated with increased transcription of SM α-actin gene. The aim of the present study was to determine whether myocardin, a SMC-selective cofactor of serum response factor (SRF), contributed to Ang II-induced increases in SM α-actin transcription. Results showed that Ang II increased myocardin mRNA expression as well as SM α-actin mRNA expression via the Ang II type 1 receptor in cultured rat aortic SMCs. Cotransfection studies revealed that CArG elements were required for Ang II-induced transcription of SM α-actin gene, and a dominant-negative form of myocardin or a short interfering RNA (siRNA) specific for myocardin decreased Ang II-induced SM α-actin transcription. Prx1, a homeodomain protein whose expression was increased by Ang II, also increased SM α-actin gene transcription in part via CArG elements, and siRNA specific for Prx1 markedly decreased basal and Ang II-induced SM α-actin transcription. Electrophoretic mobility shift assay showed that myocardin and Ang II, respectively, increased formation of a SMC-specific CArG-SRF-myocardin higher order complex. However, Ang II had no effect on binding between myocardin and SRF as determined by a mammalian two-hybrid assay, suggesting that Ang II-induced increases in formation of CArG-SRF-myocardin complex was the result of increased SRF binding to CArG elements and increased myocardin expression. Taken together, these results support a model in which Ang II-induced increases in expression of SM α-actin are mediated through Prx1-dependent increases in SRF binding to CArG elements and subsequent recruitment of myocardin.
Upregulation of Alveolar Epithelial Active Na
+
Transport Is Dependent on β
2
-Adrenergic Receptor Signaling
Authors: Mutlu Gökhan M. , Dumasius Vidas , Burhop James , McShane Pamela J. , Meng Fan Jing , Welch Lynn , Dumasius Andrew , Mohebahmadi Nima , Thakuria Gloria , Hardiman Karen , Matalon Sadis , Hollenberg Steven , Factor Phillip
Published: March 2004

Alveolar epithelial β-adrenergic receptor (βAR) activation accelerates active Na
+
transport in lung epithelial cells in vitro and speeds alveolar edema resolution in human lung tissue and normal and injured animal lungs. Whether these receptors are essential for alveolar fluid clearance (AFC) or if other mechanisms are sufficient to regulate active transport is unknown. In this study, we report that mice with no β
1
- or β
2
-adrenergic receptors (β
1
AR
−/−
/β
2
AR
−/−
) have reduced distal lung Na,K-ATPase function and diminished basal and amiloride-sensitive AFC. Total lung water content in these animals was not different from wild-type controls, suggesting that βAR signaling may not be required for alveolar fluid homeostasis in uninjured lungs. Comparison of isoproterenol-sensitive AFC in mice with β
1
- but not β
2
-adrenergic receptors to β
1
AR
−/−
/β
2
AR
−/−
mice indicates that the β
2
AR mediates the bulk of β-adrenergic-sensitive alveolar active Na
+
transport. To test the necessity of βAR signaling in acute lung injury, β
1
AR
−/−
/β
2
AR
−/−
, β
1
AR
+/+
/β
2
AR
−/−
, and β
1
AR
+/+
/β
2
AR
+/+
mice were exposed to 100% oxygen for up to 204 hours. β
1
AR
−/−
/β
2
AR
−/−
and β
1
AR
+/+
/β
2
AR
−/−
mice had more lung water and worse survival from this form of acute lung injury than wild-type controls. Adenoviral-mediated rescue of β
2
-adrenergic receptor (β
2
AR) function into the alveolar epithelium of β
1
AR
−/−
/β
2
AR
−/−
and β
1
AR
+/+
/β
2
AR
−/−
mice normalized distal lung β
2
AR function, alveolar epithelial active Na
+
transport, and survival from hyperoxia. These findings indicate that βAR signaling may not be necessary for basal AFC, and that β
2
AR is essential for the adaptive physiological response needed to clear excess fluid from the alveolar airspace of normal and injured lungs.
Defective Lung Vascular Development and Fatal Respiratory Distress in Endothelial NO Synthase-Deficient Mice
Authors: Han Robin N.N. , Babaei Saeid , Robb Malcolm , Lee Tony , Ridsdale Ross , Ackerley Cameron , Post Martin , Stewart Duncan J.
Published: March 2004

Endothelium-derived NO plays a critical role in the regulation of cardiovascular function and structure, as well as acting as a downstream mediator of the angiogenic response to numerous vascular growth factors. Although endothelial NO synthase (eNOS)-deficient mice are viable, minor congenital cardiac abnormalities have been reported and homozygous offspring exhibit high neonatal mortality out of proportion to the severity of these defects. The aim of the present report was to determine whether abnormalities of the pulmonary vascular development could contribute to high neonatal loss in eNOS-deficient animals. We now report that eNOS-deficient mice display major defects in lung morphogenesis, resulting in respiratory distress and death within the first hours of life in the majority of animals. Histological and molecular examination of preterm and newborn mutant lungs demonstrated marked thickening of saccular septae, with evidence of reduced surfactant material. Lungs of eNOS-deficient mice also exhibited a striking paucity of distal arteriolar branches and extensive regions of capillary hypoperfusion, together with misalignment of pulmonary veins, which represent the characteristic features of alveolar capillary dysplasia. We conclude that eNOS plays a previously unrecognized role in lung development, which may have relevance for clinical syndromes of neonatal respiratory distress.
FVIIa:TF Induces Cell Survival via G
12
/G
13
-Dependent Jak/STAT Activation and Bcl
XL
Production
Authors: Versteeg Henri H. , Spek C. Arnold , Slofstra Sjoukje H. , Diks Sander H. , Richel Dick J. , Peppelenbosch Maikel P.
Published: March 2004

Tissue factor (TF), apart from activating the extrinsic pathway of the blood coagulation, is a principal regulator of embryonic and oncogenic angiogenesis, inflammation, leukocyte reverse transmigration, and tumor progression. It has become clear that these events are mediated by intracellular signal transduction elicited by TF/factor VIIa (FVIIa) interaction, but the details of this signaling remain largely obscure. In this study, we show that FVIIa/TF-interaction produces STAT5 phosphorylation, STAT5 nuclear translocation and transactivation of a STAT5 reporter construct. FVIIa-dependent STAT5 activation was dependent on FVIIa proteolytic activity but not on generation of the downstream coagulation factors Xa and thrombin, nor on the TF cytoplasmic domain. FVIIa-induced STAT5 phosphorylation was dependent on functional G
12
/G
13
class G proteins and Jak2 activity, but not Jak1 or Tyk2. Finally, we show that FVIIa leads to cell survival through a Jak2/STAT5-dependent production of the antiapoptotic STAT5 target Bcl
XL
as well as Jak2-dependent activation of the antiapoptotic protein PKB. In conclusion, our results show that FVIIa induces cell survival through STAT5-dependent Bcl
XL
production and Jak2-dependent activation of PKB. Finally, we demonstrated for the first time that TF/FVIIa-signal transduction is dependent on G
12
/G
13
class G proteins.
Ca
2+
/Calmodulin-Dependent Protein Kinase II Phosphorylation Regulates the Cardiac Ryanodine Receptor
Authors: Wehrens Xander H.T. , Lehnart Stephan E. , Reiken Steven R. , Marks Andrew R.
Published: March 2004

The cardiac ryanodine receptor (RyR2)/calcium release channel on the sarcoplasmic reticulum is required for muscle excitation-contraction coupling. Using site-directed mutagenesis, we identified the specific Ca
2+
/calmodulin-dependent protein kinase II (CaMKII) phosphorylation site on recombinant RyR2, distinct from the site for protein kinase A (PKA) that mediates the “fight-or-flight” stress response. CaMKII phosphorylation increased RyR2 Ca
2+
sensitivity and open probability. CaMKII was activated at increased heart rates, which may contribute to enhanced Ca
2+
-induced Ca
2+
release. Moreover, rate-dependent CaMKII phosphorylation of RyR2 was defective in heart failure. CaMKII-mediated phosphorylation of RyR2 may contribute to the enhanced contractility observed at higher heart rates. The full text of this article is available online at
http://circres.ahajournals.org
.
GIT1 Mediates Thrombin Signaling in Endothelial Cells
Authors: van Nieuw Amerongen Geerten P. , Natarajan Kanchana , Yin Guoyong , Hoefen Ryan J. , Osawa M. , Haendeler Judith , Ridley A.J. , Fujiwara K. , van Hinsbergh Victor W.M. , Berk Bradford C.
Published: March 2004

Thrombin mediates changes in endothelial barrier function and increases endothelial permeability. A feature of thrombin-enhanced endothelial hyperpermeability is contraction of endothelial cells (ECs), accompanied by formation of focal adhesions (FAs). Recently, a G protein-coupled receptor kinase-interacting protein, GIT1, was shown to regulate FA disassembly. We hypothesized that GIT1 modulates thrombin-induced changes in FAs. In human umbilical vein ECs (HUVECs), thrombin recruited GIT1 to FAs, where GIT1 colocalized with FAK and vinculin. Recruitment of GIT1 to FAs was dependent on activation of the small GTPase RhoA, and Rho kinase, as demonstrated by adenoviral transfection of dominant-negative RhoA and treatment with Y-27632. Thrombin stimulated GIT1 tyrosine phosphorylation with a time course similar to FAK phosphorylation in a Rho kinase- and Src-dependent manner. Depletion of GIT1 with antisense GIT1 oligonucleotides had no effect on basal cell morphology, but increased cell rounding and contraction of HUVECs, increased FA formation, and increased FAK tyrosine phosphorylation in response to thrombin, concomitant with increased endothelial hyperpermeability. These data identify GIT1 as a novel mediator in agonist-dependent signaling in ECs, demonstrate that GIT1 is involved in cell shape changes, and suggest a role for GIT1 as a negative feedback regulator that augments recovery of cell contraction.
Hibernating Myocardium
Authors: Canty John M. , Suzuki Gen , Banas Michael D. , Verheyen Fons , Borgers Marcel , Fallavollita James A.
Published: March 2004

The inability to reproduce spontaneous ventricular fibrillation in an animal model of chronic coronary artery disease has limited advances in understanding mechanisms of sudden cardiac death (SCD). Swine with hibernating myocardium arising from a chronic left anterior descending coronary artery (LAD) occlusion have a high rate of SCD that parallels the poor clinical survival of medically treated patients with hibernating myocardium. Kaplan-Meier analysis (n=426) demonstrated a cumulative mortality of 49% after 5 months that was almost entirely attributable to spontaneous SCD. Using implantable loop recorders, ventricular fibrillation was documented as the arrhythmic mechanism of death in all animals (n=10) and was usually preceded by ventricular tachycardia (n=8). Physiological studies before SCD (n=7) demonstrated total LAD occlusion and collateral-dependent myocardium (n=5), excluding acute occlusion as a major trigger of arrhythmia. The physiological substrate of hibernating myocardium was present before SCD, with reductions in LAD perfusion (SCD 0.79±0.13 versus 0.80±0.08 mL/min per g) and wall thickening (SCD 28±3% versus 22±3%) that were similar to survivors (n=14). Triphenyltetrazolium chloride infarcts among animals with SCD were infrequent (4 of 32) and small, averaging 4.6% of LV mass. Histology (n=4) showed postmortem changes but no acute inflammation nor contraction band necrosis. These data support the notion that hibernating myocardium is a pathophysiological substrate at high risk of SCD. This is independent of changes in functional stenosis severity, acute myocardial necrosis, or fibrotic scar. Thus, regional adaptations that promote myocyte survival in the setting of chronic repetitive ischemia result in a substrate with enhanced vulnerability to lethal arrhythmias and SCD.
Role of Calcium Cycling Versus Restitution in the Mechanism of Repolarization Alternans
Authors: Pruvot Etienne J. , Katra Rodolphe P. , Rosenbaum David S. , Laurita Kenneth R.
Published: March 2004

T-wave alternans, a powerful marker of arrhythmic events, results from alternation in action potential duration (APD). The underlying cellular mechanism of APD alternans is unknown but has been attributed to either intracellular calcium (Ca
2+
) cycling or membrane ionic currents, manifested by a steep slope of cellular APD restitution. To address these mechanisms, high-resolution optical mapping techniques were used to measure action potentials and Ca
2+
transients simultaneously from hundreds of epicardial sites in the guinea pig model of pacing-induced T-wave alternans (n=7). The pacing rates (ie, alternans threshold) at which T-wave (369±11 bpm), APD (369±21 bpm), and Ca
2+
(371±29 bpm) alternans first appeared were comparable. Importantly, the site of origin of APD alternans and Ca
2+
alternans consistently occurred together near the base of the left ventricle, not where APD restitution was steepest. In addition, APD and Ca
2+
alternans were remarkably similar both spatially and temporally during discordant alternans. In conclusion, the mechanism underlying T-wave alternans in the intact heart is more closely associated with intracellular Ca
2+
cycling rather than APD restitution.
Atrial Natriuretic Peptide Gene Polymorphisms and Risk of Ischemic Stroke in Humans
Authors: Rubattu Speranza , Stanzione Rosita , Di Angelantonio Emanuele , Zanda Bastianina , Evangelista Anna , Tarasi David , Gigante Bruna , Pirisi Angelo , Brunetti Ercole , Volpe Massimo
Published: March 2004

Background and Purpose—

A precise definition of genetic factors responsible for common forms of stroke is still lacking. The purpose of the present study was to investigate the contributory role of the genes encoding atrial natriuretic peptide (
ANP
) and type A natriuretic peptide receptor (
NPRA
) in humans’ susceptibility to develop ischemic stroke.

Methods—

Allele and genotype frequencies of
ANP
and
NPRA
were characterized in an Italian case-control study with patients affected by vascular disease or risk factors. Subjects were recruited from the island of Sardinia (206 cases, 236 controls).

Results—

A significant association between the
ANP
/TC2238 polymorphic site and stroke occurrence was found when a recessive model of inheritance was assumed. The risk conferred by this mutant genotype, when estimated by multivariate logistic regression analysis, was 3.8 (95% confidence interval, 1.4 to 10.9). A significantly increased risk of stroke recurrence was observed among cases carrying the
ANP
/CC2238 genotype compared with cases carrying the
ANP
/TT2238 genotype (
P
=0.04). No direct association of
NPRA
with stroke occurrence was detected. However, a significant epistatic interaction between the
ANP
/CC2238 genotype and an allelic variant of
NPRA
led to a 5.5-fold increased risk of stroke (95% confidence interval, 1.5 to 19.4).

Conclusions—

Our findings support a direct contributory role of
ANP
to stroke in humans. A significant interaction between
ANP
and
NPRA
on stroke occurrence was found.
Measurement of Carotid Plaque Volume by 3-Dimensional Ultrasound
Authors: Landry Anthony , Spence J. David , Fenster Aaron
Published: March 2004

Background and PurposeMeasurement of carotid plaque volume and its progression are important tools for research and patient management. In this study, we investigate the observer variability in the measurement of plaque volume as determined by 3-dimensional (3D) ultrasound (US). We also investigate the effect of interslice distances (ISD) and repeated 3D US scans on measurement variability.

Materials and MethodsForty 3D US patient images of plaques (range, 37.43 to 604.1 mm3) were measured by manual planimetry. We applied ANOVA to determine plaque volume measurement variability and reliability. Plaque volumes were measured with 9 ISDs to determine the effect of ISD on measurement variability. Additional plaque volumes were also measured from multiple 3D US scans to investigate repeated scan acquisition variability.

ResultsIntraobserver and interobserver measurement reliabilities were 94% and 93.2%, respectively. Plaque volume measurement variability decreased with increasing plaque volume (range, 27.1% to 2.2%). Measurement precision was constant for ISDs between 1.0 and 3.0 mm, whereas plaque volume measurement variability increased with ISD. Repeated 3D US scan measurements were not different from single-scan measurements (P=0.867).

ConclusionsThe coefficient of variation in the measurement of plaque volume decreased with plaque size. The volumetric change that must be observed to establish with 95% confidence that a plaque has undergone change is ≈20% to 35% for plaques <100 mm3and ≈10% to 20% for plaques >100 mm3. Measurement precision was unchanged for ISDs <3.0 mm, whereas measurement variability increased with ISD. Repeated 3D US scans did not affect plaque volume measurement variability.
Hypoxia/Ischemia Modulates G Protein–Coupled Receptor Kinase 2 and β-Arrestin-1 Levels in the Neonatal Rat Brain
Authors: Lombardi Maria Stella , van den Tweel Evelyn , Kavelaars Annemieke , Groenendaal Floris , van Bel Frank , Heijnen Cobi J.
Published: March 2004

Background and Purpose—

Neurotransmitters, neuropeptides, chemokines, and many other molecules signal through G protein–coupled receptors (GPCRs). GPCR kinases (GRKs) and β-arrestins play a crucial role in regulating the responsiveness of multiple GPCRs. Reduced expression of GRK and β-arrestins leads to supersensitization of GPCRs and will thereby increase the response to neuropeptides and neurotransmitters. We analyzed GRK and β-arrestin expression after cerebral hypoxia/ischemia (HI).

Materials and Methods—

Twelve-day-old rat pups were exposed to 90 minutes of hypoxia (fraction of inspired oxygen [FiO
2
] 0.08) after ligation of the right carotid artery, a procedure that induces unilateral damage in the right hemisphere. At 6, 12, 24, and 48 hours after HI, the left (hypoxic) and right (hypoxic/ischemic) hemispheres were analyzed for GRK and β-arrestin protein and mRNA expression by Western blotting and real-time polymerase chain reaction, respectively. In addition, we analyzed GRK2 expression in the hippocampus by immunohistochemistry.

Results—

HI downregulated GRK2 protein expression in both hemispheres at 24 to 48 hours after HI, and the effect was more pronounced in the ipsilateral hemisphere. HI induced no global change in GRK6 protein expression. However, GRK2 was markedly decreased in the hippocampal region of the ipsilateral hemisphere that will be severely damaged after HI. No changes in global mRNA levels for GRK2 were detected. In contrast, HI increased β-arrestin-1 protein expression as well as mRNA levels at 6 to 12 hours after HI.

Conclusions—

Neonatal HI-induced brain damage is associated with specific changes in the GPCR desensitization machinery. We hypothesize that these changes result in supersensitization of multiple GPCRs and might therefore contribute to HI-induced brain damage.
Imaging the Ischemic Penumbra with
18
F-Fluoromisonidazole in a Rat Model of Ischemic Stroke
Authors: Saita Kazuko , Chen Michelle , Spratt Neil J. , Porritt Michelle J. , Liberatore Gabriel T. , Read Stephen J. , Levi Christopher R. , Donnan Geoffrey A. , Ackermann Uwe , Tochon-Danguy Henri J. , Sachinidis John I. , Howells David W.
Published: March 2004

Background and Purpose—

The ischemic penumbra is a major focus of stroke research.
18
F-fluoromisonidazole (
18
F-FMISO), a positron emission tomography (PET) marker of hypoxic cells, has shown promise as a technique to image the penumbra in humans. Our aim was to delineate the pattern of
18
F-FMISO binding in a rat middle cerebral artery transient thread-occlusion model, and correlate this with tissue outcome at 24 hours. We hypothesized that the pattern of
18
F-FMISO binding would mimic that seen in humans.

Methods—

Thirty-eight rats underwent 2 hours transient middle cerebral artery (MCA) occlusion, and then received
18
F-FMISO at time points from 0.5 to 22 hours post-MCA occlusion and were killed 2 hours later. Autoradiographic assessment of
18
F-FMISO binding and assessment (triphenyltetrazolium chloride) of the area of infarction were performed on tissue slices.

Results—

Until 1 hour after MCA occlusion,
18
F-FMISO binding was increased in the entire MCA territory, with little or no infarction visible. Over the next 5 hours, the pattern of binding evolved to a small rim of intensely binding tissue surrounding the infarct core, which itself showed reduced binding compared with the contralateral hemisphere. By 24 hours, there was minimal accumulation of
18
F-FMISO binding and a large area of infarction.

Conclusions—

The pattern of
18
F-FMISO binding rats reproduced the pattern seen in humans, consistent with this tracer being a marker of the ischemic penumbra in both species. This technique may have application in studying the ischemic penumbra in animal models, and correlating this with similar studies in humans.
Leukocyte Count as an Independent Predictor of Recurrent Ischemic Events
Authors: Grau Armin J. , Boddy Alexander W. , Dukovic Deborah A. , Buggle Florian , Lichy Christoph , Brandt Tobias , Hacke Werner
Published: March 2004

Background and Purpose—

Inflammatory markers predict first-time ischemic events. We investigated whether leukocyte and differential counts predict recurrent events and ischemic events in high-risk populations, and whether such events are preceded by acutely exacerbated inflammation.

Methods—

We studied 18 558 patients with ischemic stroke, myocardial infarction, or peripheral arterial disease who participated in the trial of Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE), a study that compared the occurrence of ischemic stroke, myocardial infarction, or vascular death under randomized treatment with aspirin or clopidogrel. Leukocyte counts were frequently assessed during followup.

Results—

Compared with the quartile with lowest leukocyte counts at baseline (<5.9×10
9
/L), patients in the top quartile (>8.2×10
9
/L) had higher risks for ischemic stroke (relative risk 1.30;
P
=0.007), myocardial infarction (relative risk 1.56,
P
<0.001), and vascular death (relative risk 1.51;
P
<0.001) after adjustment for other risk factors. Neutrophil counts contributed most to increased risk. Assessments of regression dilution effects based on replicate measurements show that these risk associations may underestimate the real associations by 30 to 50%. Treatment with aspirin or clopidogrel did not influence predictive effects by leukocytes. In the week before a recurrent event, but not at earlier time points, the leukocyte count was significantly increased over baseline levels (n=211; mean difference +0.46×10
9
/L;
P
=0.005).

Conclusions—

Leukocyte counts and mainly neutrophil counts are independently associated with ischemic events in these high-risk populations. An increase of leukocyte counts over baseline levels heralds a period of increased risk lasting about one week.