bluuebunny/crossref_metadata_2025 huggingface dataset:
Depletion of Natural Killer Cell Function Decreases Atherosclerosis in Low-Density Lipoprotein Receptor Null Mice
Authors: Whitman Stewart C. , Rateri Debra L. , Szilvassy Stephen J. , Yokoyama Wayne , Daugherty Alan
Published: March 2004

Objective—Natural killer (NK) cells are a key component of innate immunity. Despite being identified in human and mouse atherosclerotic lesions, the role of NK cells in the disease process in unknown. To determine this role, we created chimeric atherosclerosis-susceptible low-density lipoprotein (LDL) receptor null (ldl-r−/−) mice that were deficient in functional NK cells through expression of a transgene encoding for Ly49A.

Methods and Results—Bone marrow cells from Ly49A transgenic and nontransgenic littermates were used to repopulate the hematopoietic system of lethally-irradiated femaleldl-r−/−mice. After a recovery period to permit sufficient engraftment, mice were placed on a diet enriched in saturated fat and cholesterol. After 8 weeks, there was no difference in either serum total cholesterol concentrations or lipoprotein cholesterol distribution in mice repopulated with nontransgenic versus Ly49A transgenic marrow cells. Using immunohistochemistry, we detected NK cells in atherosclerotic lesions of both groups of mice. However, deficiency of functional NK cells significantly reduced the size of atherosclerosis by 70% (P=0.0002) in cross-sectional analysis of the aortic root and by 38% (P=0.004) inen faceanalysis of the intimal surface of the aortic arch.

Conclusion—These studies demonstrate that NK cells infiltrate the vessel wall and promote atherosclerotic lesion development.
Thalidomide as a Potent Inhibitor of Neointimal Hyperplasia After Balloon Injury in Rat Carotid Artery
Authors: Park Seung-Jung , Kim Hyo-Soo , Yang Han-Mo , Park Kyung-Woo , Youn Seock-Won , Jeon Soo-In , Kim Dae-Hee , Koo Bon-Kwon , Chae In-Ho , Choi Dong-Joo , Oh Byung-Hee , Lee Myoung-Mook , Park Young-Bae
Published: March 2004

Objective—

Inflammation is one of the main pathogeneses of neointimal hyperplasia after coronary intervention. Thalidomide, because of its potent antiinflammatory and immunomodulatory properties, is being re-evaluated in several clinical fields. Therefore, we examined whether thalidomide therapy affects neointimal formation.

Methods and Results—

In male Sprague-Dawley rats, 100 mg/kg of either thalidomide or sucrose (control) was administered daily from 3 days before injury to 2 weeks after conventional carotid artery denudation injury. Thalidomide administration resulted in a significant reduction of neointimal formation (neointima to media ratio 1.26±0.29 versus 0.35±0.13,
P
<0.001) and proliferative activity of vascular smooth muscle cells. In addition, arterial macrophage infiltration and local expressions of tumor necrosis factor alpha (TNF-α) and basic fibroblast growth factor (bFGF) in the injured arteries as measured by immunohistochemistry and immunoblot analysis were significantly reduced by thalidomide treatment. Serum TNF-α, measured by ELISA, was also significantly reduced in the thalidomide-treated animals compared with controls after injury (856±213 versus 449±68 pg/mL on day 3,
P
=0.001; 129±34 versus 63±18 pg/mL on day 14,
P
=0.001), and we observed a good positive correlation between the serum TNF-α levels and the severity of neointimal growth.

Conclusions—

We found that thalidomide, through its antiinflammatory and antiproliferative effects, significantly inhibits neointimal hyperplasia in balloon-injured rat carotid arteries. Our results suggest a potential role of thalidomide as a potent inhibitor of neointimal formation after angioplasty.
Delay in Right Ventricular Activation Contributes to Brugada Syndrome
Authors: Tukkie Raymond , Sogaard Peter , Vleugels Jim , de Groot Irma K.L.M. , Wilde Arthur A.M. , Tan Hanno L.
Published: March 2004

Background—

Although Brugada syndrome revolves around reduced net depolarizing force, the electrophysiological mechanisms of its defining features (right precordial ST-segment elevation and ventricular tachyarrhythmias) remain unresolved. Two proposed mechanisms are (1) right ventricular (RV) conduction delay and (2) selective and significant RV subepicardial action potential shortening. Both mechanisms must cause disparate contractile changes: delay in RV contraction and reduction of contractile force, respectively. We aimed to establish the electrophysiological mechanism of Brugada syndrome by studying the timing and force of RV contraction.

Methods and Results—

Using tissue Doppler echocardiography, we studied how these contractile variables change on induction of the characteristic ST-segment changes of Brugada syndrome by flecainide challenge. Accordingly, we studied patients in whom flecainide induced these changes (inducible) and those in whom these changes were not induced (control). We found that (1) the occurrence of a positive response (coved-type ST elevation) after flecainide coincides with delay in the onset of contraction between the RV and left ventricle (LV); (2) the extent of contraction delay between RV and LV correlates with the magnitude of ST elevation; and (3) RV ejection time (duration of RV ejection phase) shortens as the Brugada ECG pattern emerges.

Conclusions—

These results indicate that both proposed mechanisms of Brugada syndrome may be operative.
Coronary Hyperemic Dose Responses of Intracoronary Sodium Nitroprusside
Authors: Parham Walter A. , Bouhasin Andre , Ciaramita Jeffrey P. , Khoukaz Souheil , Herrmann Steven C. , Kern Morton J.
Published: March 2004

Background—

Sodium nitroprusside is one of several agents considered effective for treating the no-reflow phenomenon during acute coronary interventions. However, the coronary hyperemic dose responses and systemic hemodynamic effects of intracoronary nitroprusside have yet to be determined in humans. The purpose of this study was to compare the hyperemic and hemodynamic responses of intracoronary nitroprusside to intracoronary adenosine in patients during cardiac catheterization with angiographically normal anterior descending arteries.

Methods and Results—

In 21 patients, coronary blood flow velocity (0.014-inch Doppler flow wire), heart rate, and blood pressure were measured in unobstructed left anterior descending coronary arteries at rest, after intracoronary adenosine (30- to 50-μg boluses), and after 3 serial doses (0.3-, 0.6-, and 0.9-μg/kg boluses) of intracoronary nitroprusside. Coronary reserve was calculated as hyperemia/basal coronary flow velocity. In an additional 9 patients with intermediate stenoses (53±7%), 14 fractional flow reserve (FFR) measurements (using 0.014-inch pressure wire) were performed with both intracoronary adenosine and nitroprusside (0.6 μg/kg). Intracoronary nitroprusside produced equivalent coronary hyperemia with a longer duration (≈25%) compared with intracoronary adenosine. Intracoronary nitroprusside (0.9 μg/kg) decreased systolic blood pressure by <20%, with minimal change in heart rate, whereas intracoronary adenosine had no effect on these parameters. FFR measurements with intracoronary nitroprusside were identical to those obtained with intracoronary adenosine (
r
=0.97).

Conclusions—

Compared with adenosine, intracoronary nitroprusside produces an equivalent but more prolonged coronary hyperemic response in normal coronary arteries. Intracoronary nitroprusside, in doses commonly used for the treatment of the no-reflow phenomenon, can produce sustained coronary hyperemia without detrimental systemic hemodynamics. On the basis of FFR measurements compared with adenosine, sodium nitroprusside also appears to be a suitable hyperemic stimulus for coronary physiological measurements.
Heat-Shock Protein 60-Reactive CD4
+
CD28
null
T Cells in Patients With Acute Coronary Syndromes
Authors: Zal Behnam , Kaski Juan Carlos , Arno Gavin , Akiyu Julius P. , Xu Qingbo , Cole Della , Whelan Michael , Russell Nick , Madrigal J. Alejandro , Dodi I. Anthony , Baboonian Christina
Published: March 2004

Background—

CD4
+
CD28
null
T cells are present in increased numbers in the peripheral blood of patients with acute coronary syndrome (ACS) compared with patients with chronic stable angina (CSA). The triggers of activation and expansion of these cells to date remain unclear.

Methods and Results—

Twenty-one patients with ACS and 12 CSA patients with angiographically confirmed coronary artery disease and 9 healthy volunteers were investigated. Peripheral blood leukocytes were stimulated with human cytomegalovirus (HCMV),
Chlamydia pneumoniae
, human heat-shock protein 60 (hHSP60), or oxidized LDL (ox-LDL). CD4
+
CD28
null
cells were separated by flow cytometry and assessed for antigen recognition using upregulation of interferon-γ and perforin mRNA transcription as criteria for activation. CD4
+
CD28
null
cells from 12 of 21 patients with ACS reacted with hHSP60. No response was detected to HCMV,
C pneumoniae
, or ox-LDL. Incubation of the cells with anti-MHC class II and anti-CD4 antibodies but not anti-class I antibodies blocked antigen presentation, confirming recognition of the hHSP60 to be via the MHC class II pathway. Patients with CSA had low numbers of CD4
+
CD28
null
cells. These cells were nonreactive to any of the antigens used. Circulating CD4
+
CD28
null
cells were present in 5 of the 9 healthy controls. None reacted with hHSP60.

Conclusions—

We have shown that hHSP60 is an antigen recognized by CD4
+
CD28
null
T cells of ACS patients. Endothelial cells express hHSP60 either constitutively or under stress conditions. Circulating hHSP60-specific CD4
+
CD28
null
cells may, along other inflammatory mechanisms, contribute to vascular damage in these patients.
Characterization of Left Ventricular Activation in Patients With Heart Failure and Left Bundle-Branch Block
Authors: Auricchio Angelo , Fantoni Cecilia , Regoli Francois , Carbucicchio Corrado , Goette Andreas , Geller Christoph , Kloss Michael , Klein Helmut
Published: March 2004

Background—

Conventional activation mapping in the dilated human left ventricle (LV) with left bundle-branch block (LBBB) morphology is incomplete given the limited number of recording sites that may be collected in a reasonable time and given the lack of precision in marking specific anatomic locations.

Methods and Results—

We studied LV activation sequences in 24 patients with heart failure and LBBB QRS morphology with simultaneous application of 3D contact and noncontact mapping during intrinsic rhythm and asynchronous pacing. Approximately one third of the patients with typical LBBB QRS morphology had normal transseptal activation time and a slightly prolonged or near-normal LV endocardial activation time. A “U-shaped” activation wave front was present in 23 patients because of a line of block that was located anteriorly (n=12), laterally (n=8), and inferiorly (n=3). Patients with a lateral line of block had significantly shorter QRS (
P
<0.003) and transseptal durations (
P
<0.001) and a longer distance from the LV breakthrough site to line of block (
P
<0.03). Functional behavior of the line of block was demonstrated by a change in its location during asynchronous ventricular pacing at different sites and cycle lengths.

Conclusions—

A U-shaped conduction pattern is imposed on the LV activation sequence by a transmural functional line of block located between the LV septum and the lateral wall with a prolonged activation time. Assessment of functional block is facilitated by noncontact mapping, which may be useful for identifying and targeting specific locations that are optimal for successful cardiac resynchronization therapy.
Heart Failure and the Risk of Shocks in Patients With Implantable Cardioverter Defibrillators
Authors: Whang William , Mittleman Murray A. , Rich David Q. , Wang Paul J. , Ruskin Jeremy N. , Tofler Geoffrey H. , Muller James E. , Albert Christine M.
Published: March 2004

Background—

Left ventricular ejection fraction (LVEF) predicts device discharges in patients with implantable cardioverter-defibrillators (ICDs). The relationship between severity of congestive heart failure (CHF) and ICD discharges is less clear.

Methods and Results—

We prospectively analyzed the association between CHF and risk of appropriate ICD discharges in the Triggers Of Ventricular Arrhythmias (TOVA) study, a cohort study of ICD patients conducted at 31 centers in the United States. Reported shocks were confirmed for sustained ventricular tachycardia (VT) or fibrillation (VF) by analysis of stored electrograms. Proportional hazards models included CHF categorized by New York Heart Association class. Baseline CHF was present among 502 (44%) of 1140 patients; 170 (34%) had class I, 230 (46%) had class II, 97 (19%) had class III, and only 5 (1%) had class IV symptoms. During median follow-up of 212 days, 92 patients experienced 1 or more appropriate ICD discharges. Class III CHF was associated in a statistically significantly manner with ICD discharge for VT/VF (hazard ratio 2.40, 95% CI 1.16 to 4.98), even with adjustment for LVEF. The combination of LVEF <0.20 and class III symptoms resulted in a particularly high risk of shocks for VT/VF (hazard ratio 3.90, 95% CI 1.28 to 11.92).

Conclusions—

Class III CHF, an easily accessible clinical measure, is an independent risk factor, along with LVEF, for ventricular arrhythmias that require shock therapy among ICD patients. Whether patients with class III CHF benefit to a greater degree from ICDs and whether aggressive treatment of CHF in ICD patients may prevent ventricular arrhythmias remains to be determined.
Predictive Value of Noninvasive Measures of Atherosclerosis for Incident Myocardial Infarction
Authors: van der Meer Irene M. , Bots Michiel L. , Hofman Albert , Iglesias del Sol Antonio , van der Kuip Deirdre A.M. , Witteman Jacqueline C.M.
Published: March 2004

Background—

Several noninvasive methods are available to investigate the severity of extracoronary atherosclerotic disease. No population-based study has yet examined whether differences exist between these measures with regard to their predictive value for myocardial infarction (MI) or whether a given measure of atherosclerosis has predictive value independently of the other measures.

Methods and Results—

At the baseline (1990–1993) examination of the Rotterdam Study, a population-based cohort study among subjects age ≥55 years, carotid plaques and intima-media thickness (IMT) were measured by ultrasound, abdominal aortic atherosclerosis by x-ray, and lower-extremity atherosclerosis by computation of the ankle-arm index. In the present study, 6389 subjects were included; 258 cases of incident MI occurred before January 1, 2000. All 4 measures of atherosclerosis were good predictors of MI independently of traditional cardiovascular risk factors. Hazard ratios were equally high for carotid plaques (1.83 [1.27 to 2.62], severe versus no atherosclerosis), carotid IMT (1.95 [1.19 to 3.19]), and aortic atherosclerosis (1.94 [1.30 to 2.90]) and slightly lower for lower-extremity atherosclerosis (1.59 [1.05 to 2.39]), although differences were small. The hazard ratio for MI for subjects with severe atherosclerosis according to a composite atherosclerosis score was 2.77 (1.70 to 4.52) compared with subjects with no atherosclerosis. The predictive value of MI for a given measure of atherosclerosis was independent of the other atherosclerosis measures.

Conclusions—

Noninvasive measures of extracoronary atherosclerosis are strong predictors of MI. The relatively crude measures directly assessing plaques in the carotid artery and abdominal aorta predict MI equally well as the more precisely measured carotid IMT.
Contribution of Stent Underexpansion to Recurrence After Sirolimus-Eluting Stent Implantation for In-Stent Restenosis
Authors: Fujii Kenichi , Mintz Gary S. , Kobayashi Yoshio , Carlier Stéphane G. , Takebayashi Hideo , Yasuda Takenori , Moussa Issam , Dangas George , Mehran Roxana , Lansky Alexandra J. , Reyes Arlene , Kreps Edward , Collins Michael , Colombo Antonio , Stone Gregg W. , Teirstein Paul S. , Leon Martin B. , Moses Jeffrey W.
Published: March 2004

Background—

We used intravascular ultrasound (IVUS) to evaluate recurrence after sirolimus-eluting stent (SES) implantation treatment of in-stent restenosis (ISR).

Methods and Results—

Forty-eight ISR lesions (41 patients with objective evidence of ischemia) were treated with SES. Recurrent ISR was identified in 11 lesions (all focal); repeat revascularization was performed in 10. These were compared with 16 patients (19 lesions) without recurrence as documented by angiography. Nine of 11 recurrent lesions had a minimum stent area (MSA) <5.0 mm
2
versus 5 of 19 nonrecurrent lesions (
P
=0.003); 7 of 11 recurrent lesions had an MSA <4.0 mm
2
versus 4 of 19 nonrecurrent lesions (
P
=0.02); and 4 of 11 recurrent lesions had an MSA <3.0 mm
2
versus 1 of 19 nonrecurrent lesions (
P
=0.03). A gap between SESs was identified in 3 of 11 recurrences versus 1 of 19 nonrecurrent lesions.

Conclusions—

Stent underexpansion is a significant cause of failure after SES implantation treatment of ISR.
Time Dependence of Mortality Risk and Defibrillator Benefit After Myocardial Infarction
Authors: Wilber David J. , Zareba Wojciech , Hall W. Jackson , Brown Mary W. , Lin Albert C. , Andrews Mark L. , Burke Martin , Moss Arthur J.
Published: March 2004

Background—

Prophylactic implantable defibrillators (ICDs) improve survival in patients with impaired ventricular function after myocardial infarction (MI), but it is uncertain whether mortality risk and survival benefit depend on the elapsed time from MI.

Methods and Results—

The Multicenter Automatic Defibrillator Implantation Trial II examined the impact of ICDs on survival in post-MI patients with ejection fractions ≤30%. In 1159 patients, mean time from most recent MI to enrollment was 81±78 months. Patients were randomized to an ICD (n=699) or conventional care (n=460) in a 3:2 ratio. Mortality rates (deaths per 100 person-years of follow-up) in both treatment groups were analyzed by time from MI divided into quartiles (<18, 18 to 59, 60 to 119, and ≥120 months). In conventional care patients, these rates increased as time from MI increased (7.8%, 8.4%, 11.6%, 14.0%;
P
=0.03). Mortality rates in ICD patients were consistently lower in each quartile and showed minimal increase over time (7.2%, 4.9%, 8.2%, 9.0%;
P
=0.19). Covariate-adjusted hazard ratios for risk of death associated with ICD therapy were 0.97 (95% CI, 0.51 to 1.81;
P
=0.92) for recent MI (<18 months) and 0.55 (95% CI, 0.39 to 0.78;
P
=0.001) for remote MI (≥18 months).

Conclusions—

Mortality risk in patients with ejection fractions ≤30% increases as a function of time from MI. The survival benefit associated with ICDs appears to be greater for remote MI and remains substantial for up to ≥15 years after MI.
Clinical, Angiographic, and Procedural Predictors of Angiographic Restenosis After Sirolimus-Eluting Stent Implantation in Complex Patients
Authors: Lemos Pedro A. , Hoye Angela , Goedhart Dick , Arampatzis Chourmouzios A. , Saia Francesco , van der Giessen Willem J. , McFadden Eugene , Sianos Georgios , Smits Pieter C. , Hofma Sjoerd H. , de Feyter Pim J. , van Domburg Ron T. , Serruys Patrick W.
Published: March 2004

Background—

The factors associated with the occurrence of restenosis after sirolimus-eluting stent (SES) implantation in complex cases are currently unknown.

Methods and Results—

A cohort of consecutive complex patients treated with SES implantation was selected according to the following criteria: (1) treatment of acute myocardial infarction, (2) treatment of in-stent restenosis, (3) 2.25-mm diameter SES, (4) left main coronary stenting, (5) chronic total occlusion, (6) stented segment >36 mm, and (7) bifurcation stenting. The present study population was composed of 238 patients (441 lesions) for whom 6-month angiographic follow-up data were obtained (70% of eligible patients). Significant clinical, angiographic, and procedural predictors of post-SES restenosis were evaluated. Binary in-segment restenosis was diagnosed in 7.9% of lesions (6.3% in-stent, 0.9% at the proximal edge, 0.7% at the distal edge). The following characteristics were identified as independent multivariate predictors: treatment of in-stent restenosis (OR 4.16, 95% CI 1.63 to 11.01;
P
<0.01), ostial location (OR 4.84, 95% CI 1.81 to 12.07;
P
<0.01), diabetes (OR 2.63, 95% CI 1.14 to 6.31;
P
=0.02), total stented length (per 10-mm increase; OR 1.42, 95% CI 1.21 to 1.68;
P
<0.01), reference diameter (per 1.0-mm increase; OR 0.46, 95% CI 0.24 to 0.87;
P
=0.03), and left anterior descending artery (OR 0.30, 95% CI 0.10 to 0.69;
P
<0.01).

Conclusions—

Angiographic restenosis after SES implantation in complex patients is an infrequent event, occurring mainly in association with lesion-based characteristics and diabetes mellitus.
Aldosterone, Through Novel Signaling Proteins, Is a Fundamental Molecular Bridge Between the Genetic Defect and the Cardiac Phenotype of Hypertrophic Cardiomyopathy
Authors: Tsybouleva Natalia , Zhang Lianfeng , Chen Suetnee , Patel Rajnikant , Lutucuta Silvia , Nemoto Shintaro , DeFreitas Gilberto , Entman Mark , Carabello Blase A. , Roberts Robert , Marian A.J.
Published: March 2004

Background—

Human hypertrophic cardiomyopathy (HCM), the most common cause of sudden cardiac death in the young, is characterized by cardiac hypertrophy, myocyte disarray, and interstitial fibrosis. The genetic basis of HCM is largely known; however, the molecular mediators of cardiac phenotypes are unknown.

Methods and Results—

We show myocardial aldosterone and aldosterone synthase mRNA levels were elevated by 4- to 6-fold in humans with HCM, whereas cAMP levels were normal. Aldosterone provoked expression of hypertrophic markers (
NPPA
,
NPPB
, and
ACTA1
) in rat cardiac myocytes by phosphorylation of protein kinase D (PKD) and expression of collagens (
COL1A1
,
COL1A2
, and
COL3A1
) and transforming growth factor-β1 in rat cardiac fibroblasts by upregulation of phosphoinositide 3-kinase (PI3K)-p100δ. Inhibition of PKD and PI3K-p110δ abrogated the hypertrophic and profibrotic effects, respectively, as did the mineralocorticoid receptor (MR) antagonist spironolactone. Spironolactone reversed interstitial fibrosis, attenuated myocyte disarray by 50%, and improved diastolic function in the cardiac troponin T (cTnT)-Q92 transgenic mouse model of human HCM. Myocyte disarray was associated with increased levels of phosphorylated β-catenin (serine 38) and reduced β-catenin–N-cadherin complexing in the heart of cTnT-Q92 mice. Concordantly, distribution of N-cadherin, predominantly localized to cell membrane in normal myocardium, was diffuse in disarrayed myocardium. Spironolactone restored β-catenin–N-cadherin complexing and cellular distribution of N-cadherin and reduced myocyte disarray in 2 independent randomized studies.

Conclusions—

The results implicate aldosterone as a major link between sarcomeric mutations and cardiac phenotype in HCM and, if confirmed in additional models, signal the need for clinical studies to determine the potential beneficial effects of MR blockade in human HCM.
Loss of Matrix Metalloproteinase-9 or Matrix Metalloproteinase-12 Protects Apolipoprotein E–Deficient Mice Against Atherosclerotic Media Destruction but Differentially Affects Plaque Growth
Authors: Luttun Aernout , Lutgens Esther , Manderveld Ann , Maris Katleen , Collen Désiré , Carmeliet Peter , Moons Lieve
Published: March 2004

Background—

Epidemiological and histological evidence implicates proteinases of the matrix metalloproteinase (MMP) family in atherosclerosis and aneurysm formation. We previously indicated a role for urokinase-type plasminogen activator in atherosclerotic media destruction by proteolytic activation of MMPs. However, the role of specific MMPs, such as MMP-9 and MMP-12, in atherosclerosis remains undefined.

Methods and Results—

MMP-9– or MMP-12–deficient mice were crossed in the atherosclerosis-prone apolipoprotein E–deficient background and fed a cholesterol-rich diet. Mice were killed at 15 or 25 weeks of diet to study intermediate and advanced lesions, respectively. Loss of MMP-9 reduced atherosclerotic burden throughout the aorta and impaired macrophage infiltration and collagen deposition, while MMP-12 deficiency did not affect lesion growth. MMP-9 or MMP-12 deficiency conferred significant protection against transmedial elastin degradation and ectasia in the atherosclerotic media.

Conclusions—

This study is the first to provide direct genetic evidence for a significant involvement of MMP-9, but not of MMP-12, in atherosclerotic plaque growth. In addition, deficiency of MMP-9 or MMP-12 protected apolipoprotein E–deficient mice against atherosclerotic media destruction and ectasia, mechanisms that implicate the involvement of these MMPs in aneurysm formation.
Rosiglitazone Facilitates Angiogenic Progenitor Cell Differentiation Toward Endothelial Lineage
Authors: Wang Chao-Hung , Ciliberti Nadia , Li Shu-Hong , Szmitko Paul E. , Weisel Richard D. , Fedak Paul W.M. , Al-Omran Mohammed , Cherng Wen-Jin , Li Ren-Ke , Stanford William L. , Verma Subodh
Published: March 2004

Background—

Peroxisome proliferator–activated receptor-γ (PPAR-γ) agonists inhibit vascular smooth muscle proliferation and migration and improve endothelial function. It is unknown whether PPAR-γ agonists favorably modulate bone marrow (BM)–derived angiogenic progenitor cells (APCs) to promote endothelial lineage differentiation and early reendothelialization after vascular intervention.

Methods and Results—

C57/BL6 mice, treated with or without rosiglitazone (8 mg/kg per day), a PPAR-γ agonist, underwent femoral angioplasty. Rosiglitazone treatment attenuated neointimal formation (intima/media ratio: 0.98±0.12 [rosiglitazone] versus 3.1±0.5 [control];
P
<0.001; n=10 per group). Using a BM transplantation model, we identified that 58±12% of the cells within the neointima at 4 weeks were derived from the BM. Pure endothelial marker–positive, pure α-smooth muscle actin (αSMA)–positive, or double-positive APCs could be found both in mouse BM and in human peripheral blood after culture in conditional medium enriched with vascular endothelial growth factor. Rosiglitazone caused a 6-fold (
P
<0.001) increase in colony formation by human endothelial progenitor cells, promoted the differentiation of APCs toward the endothelial lineage in mouse BM in vivo (0.66±0.06% [control] to 0.95±0.08% [rosiglitazone];
P
<0.05) and in human peripheral blood in vitro (13.2±1.5% [control] to 28.4±3.3% [rosiglitazone];
P
<0.05), and inhibited the differentiation toward the smooth muscle cell lineage. Within the neointima, rosiglitazone also stimulated APCs to differentiate into mature endothelial cells and caused earlier reendothelialization compared with controls (31±5 versus 8±2 CD31-positive cells per millimeter of neointimal surface on day 14;
P
<0.01).

Conclusions—

Similar to embryonic stem cell–derived progenitors, the adult BM and peripheral blood harbor APCs that are at least bipotential and able to differentiate into endothelial and smooth muscle lineages. The PPAR-γ agonist rosiglitazone promotes the differentiation of these APCs toward the endothelial lineage and attenuates restenosis after angioplasty.
PI3-Kinase Upregulation and Involvement in Spontaneous Tone in Arteries From DOCA-Salt Rats
Authors: Northcott Carrie A. , Hayflick Joel S. , Watts Stephanie W.
Published: March 2004

Increased expression of phosphoinositide 3-kinase (PI3-kinase) mediates elevated tone in the aorta from hypertensive deoxycorticosterone acetate (DOCA)-salt rats. In this article, we hypothesized that (1) alterations observed with respect to PI3-kinase observed in the aorta would also occur in mesenteric resistance arteries responsible for determining total peripheral resistance (TPR) and (2) p110δ activity was increased and localized to vascular smooth muscle cells (VSMCs), and was responsible for the increase in spontaneous tone in aortae from DOCA-salt rats. Mesenteric resistance arteries and aorta were isolated from DOCA-salt (190±3 mm Hg) and sham (121±2 mm Hg) rats. Myograph experiments revealed LY294002 (20 μmol/L), a PI3-kinase inhibitor, significantly decreased tone in mesenteric resistance arteries from DOCA-salt rats as compared with sham (−49±12 mg versus −10±7 mg). Western analyses of resistance artery protein homogenate revealed p85α and p110δ subunit protein, with significantly elevated levels of p110δ protein in the DOCA-salt compared with sham rats (0.30±0.07 versus 0.16±0.04% smooth muscle alpha-actin arbitrary units). Immunohistochemistry revealed p110δ-specific staining in VSMCs, with more intense staining in aortae from DOCA-salt rats. Compared with aortae from sham, p110δ-associated PI3-kinase activity was increased in DOCA-salt (158% of sham) and likely responsible for spontaneous tone because the p110δ specific inhibitor IC87114 decreased spontaneous tone in a concentration-dependent manner. Collectively, these data further implicate the p110δ isoform of PI3-kinase in arterial hyperresponsiveness in hypertension at the level of both large and small arteries.
Ghrelin Acts at the Nucleus of the Solitary Tract to Decrease Arterial Pressure in Rats
Authors: Lin Yingzi , Matsumura Kiyoshi , Fukuhara Masayo , Kagiyama Shuntaro , Fujii Koji , Iida Mitsuo
Published: March 2004

Ghrelin is an orexigenic peptide originally isolated from the stomach. Intracerebroventricular administration of ghrelin has been shown to elicit decreases in arterial pressure and renal sympathetic nerve activity in conscious rabbits. The aim of the present study was to determine the role of ghrelin in the brain stem in cardiovascular responses in rats. Unilateral microinjection of ghrelin into the nucleus of the solitary tract significantly decreased the mean arterial pressure and heart rate (−17.3±0.8 mm Hg and −13.6±3.5 bpm by 20 pmol). The microinjection of ghrelin into the nucleus of the solitary tract also suppressed the renal sympathetic nerve activity (−29.5±3.4%;
P
<0.0001). Pretreatment with intravenous injection of pentolinium (5 mg/kg), a ganglion-blocking agent, eliminated these cardiovascular responses induced by the microinjection of ghrelin (20 pmol) into the nucleus of the solitary tract; however, pretreatment with intravenous injection of atropine sulfate (0.1 mg/kg), an antagonist of muscarinic acetylcholine receptors, failed to prevent them. In contrast, unilateral microinjection of ghrelin into the area postrema, rostral, and caudal ventrolateral medulla caused no significant changes in the mean arterial pressure and heart rate. On the other hand, immunohistochemical study revealed that the receptor for ghrelin, the growth hormone secretagogue receptor, was expressed in the neuronal cells of the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, but not in the cells of the area postrema. These results suggest that ghrelin acts at the nucleus of the solitary tract to suppress sympathetic activity and to decrease arterial pressure in rats.
Major Quantitative Trait Locus for Resting Heart Rate Maps to a Region on Chromosome 4
Authors: Martin Lisa J. , Comuzzie Anthony G. , Sonnenberg Gabriele E. , Myklebust Joel , James Roland , Marks Jacqueline , Blangero John , Kissebah Ahmed H.
Published: March 2004

Multiple studies have identified resting heart rate as a risk factor for cardiovascular disease independent of other cardiovascular disease risk factors (such as dyslipidemia and hypertension). Previous studies have examined heart rate in hypertensive individuals, but little is known about the genetic determination of resting heart rate in a normal population. Therefore, our objective was to perform a genome screen on a population containing normotensive and hypertensive individuals. We performed variance decomposition linkage analysis using maximum likelihood methods at ≈10 cM intervals in 2209 individuals of predominantly North European ancestry. We estimated the heritability of resting heart rate to be 26% and obtained significant evidence of linkage (logarithm of the odds [LOD]=3.9) for resting heart rate on chromosome 4q. This signal is in the same region as a quantitative trait locus (QTL) for long QT syndrome 4 and a QTL for heart rate in rats. Within the 1-LOD unit support interval, there are 2 strong candidates: ankyrin-B and myozenin 2.
Developmentally Regulated Switching of Titin Size Alters Myofibrillar Stiffness in the Perinatal Heart
Authors: Opitz Christiane A. , Leake Mark C. , Makarenko Irina , Benes Vladimir , Linke Wolfgang A.
Published: March 2004

Before birth, the compliance of the heart is limited predominantly by extracardiac constraint. Reduction of this constraint at birth requires that myocardial compliance be determined mainly by the heart’s own constituents. Because titin is a principal contributor to ventricular passive tension (PT), we studied the expression and mechanics of cardiac-titin isoforms during perinatal rat heart development. Gel electrophoresis and immunoblotting revealed a single, 3.7-MDa, N2BA isoform present 6 days before birth and an additional, also previously unknown, N2BA isoform of 3.5 to 3.6 MDa expressed in the near-term fetus. These large isoforms rapidly disappear after birth and are replaced by a small N2B isoform (3.0 MDa) predominating in 1-week-old and adult rats. In addition, neonatal pig hearts showed large N2BA-titin isoforms distinct from those present in the adult porcine myocardium. By quantitative reverse transcriptase–polymerase chain reaction, developmentally expressed titin-mRNA species were detected in rat heart. Titin-based PT was much lower (≈15 times) in fetal than adult rat cardiomyocytes, and measured PT levels were readily predictable with a model of worm-like chain titin elasticity. Immunofluorescence microscopy showed the extensibility of the differentially spliced molecular spring regions of fetal/neonatal titin isoforms in isolated rat cardiomyofibrils. Whereas the titin-isoform shift by 700 kDa ensures high passive stiffness of the postnatal cardiac myofibrils, the expression of specific fetal/neonatal cardiac-titin isoforms may also have important functions for contractile properties, myofibril assembly or turnover, and myocardial signaling during perinatal heart development.
Reconstituted High-Density Lipoprotein Inhibits Thrombin-Induced Endothelial Tissue Factor Expression Through Inhibition of RhoA and Stimulation of Phosphatidylinositol 3-Kinase but not Akt/Endothelial Nitric Oxide Synthase
Authors: Viswambharan Hema , Ming Xiu-Fen , Zhu Shengsi , Hubsch Alphonse , Lerch Peter , Vergères Guy , Rusconi Sandro , Yang Zhihong
Published: March 2004

Endothelial cells express negligible amounts of tissue factor (TF) that can be induced by thrombin, which is important for acute coronary syndromes. Recent research suggests that endothelial TF expression is positively regulated by RhoA and p38
mapk
, but negatively by Akt/endothelial nitric oxide synthase (eNOS) pathway. High-density lipoprotein (HDL) is atheroprotective and exerts antiatherothrombotic effect. This study investigated the effect of a reconstituted HDL (rHDL) on endothelial TF expression induced by thrombin and the underlying mechanisms. In cultured human umbilical vein and aortic endothelial cells, thrombin (4 U/mL, 4 hours) increased TF protein level, which was reduced by rHDL (0.1 mg/mL, 43% inhibition, n=3 to 7,
P
<0.01). Activation of RhoA but not p38
mapk
by thrombin was prevented by rHDL. rHDL stimulated Akt/eNOS pathway. The phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin or LY294002 abolished the activation of Akt/eNOS and reversed the inhibitory effect of rHDL on TF expression. Adenoviral expression of the active PI3K mutant (p110) reduced TF expression stimulated by thrombin without inhibiting RhoA activation, whereas expression of the active Akt mutant (m/p) further facilitated TF upregulation by thrombin. Moreover, a dominant-negative Akt mutant (KA) reduced thrombin’s effect and did not reverse the rHDL’s inhibitory effect on TF expression. Inhibition of eNOS by
N
ω
-nitro-
l
-arginine methyl ester (100 μmol/L) did not affect the rHDL’s effect. In conclusion, rHDL inhibits thrombin-induced human endothelial TF expression through inhibition of RhoA and activation of PI3K but not Akt/eNOS. These findings implicate a novel mechanism of antiatherothrombotic effects of HDL.
Nuclear Targeting of Akt Enhances Kinase Activity and Survival of Cardiomyocytes
Authors: Shiraishi Isao , Melendez Jaime , Ahn Youngkeun , Skavdahl Maryanne , Murphy Elizabeth , Welch Sara , Schaefer Erik , Walsh Kenneth , Rosenzweig Anthony , Torella Daniele , Nurzynska Daria , Kajstura Jan , Leri Annarosa , Anversa Piero , Sussman Mark A.
Published: March 2004

Heart failure is associated with death of cardiomyocytes leading to loss of contractility. Previous studies using membrane-targeted Akt (myristolated-Akt), an enzyme involved in antiapoptotic signaling, showed inhibition of cell death and prevention of pathogenesis induced by cardiomyopathic stimuli. However, recent studies by our group have found accumulation of activated Akt in the nucleus, suggesting that biologically relevant target(s) of Akt activity may be located there. To test this hypothesis, a targeted Akt construct was created to determine the antiapoptotic action of nuclear Akt accumulation. Nuclear localization of the adenovirally encoded Akt construct was confirmed by confocal microscopy. Cardiomyocytes expressing nuclear-targeted Akt showed no evidence of morphological remodeling such as altered myofibril density or hypertrophy. Nuclear-targeted Akt significantly elevated levels of phospho-Akt and kinase activity and inhibited apoptosis as effectively as myristolated-Akt in hypoxia-induced cell death. Transgenic overexpression of nuclear-targeted Akt did not result in hypertrophic remodeling, altered cardiomyocyte DNA content or nucleation, or enhanced phosphorylation of typical cytoplasmic Akt substrates, yet transgenic hearts were protected from ischemia-reperfusion injury. Gene array analyses demonstrated changes in the transcriptional profile of Akt/nuc hearts compared with nontransgenic controls distinct from prior characterizations of Akt expression in transgenic hearts. Collectively, these experiments show that targeting of Akt to the nucleus mediates inhibition of apoptosis without hypertrophic remodeling, opening new possibilities for therapeutic applications of nuclear-targeted Akt to inhibit cell death associated with heart disease.
Cardiac Myocytes Activated by Septic Plasma Promote Neutrophil Transendothelial Migration
Authors: Madorin W. Sean , Rui Tao , Sugimoto Naohito , Handa Osamu , Cepinskas Gediminas , Kvietys Peter R.
Published: March 2004

Cardiac myocytes isolated from rats with peritonitis (cecal ligation and perforation; CLP) promote PMN transendothelial migration. Herein, we assessed (1) the mechanisms involved in cardiac myocyte activation during peritonitis and (2) the means by which these activated myocytes promote PMN transendothelial migration. Plasma obtained from mice subjected to CLP (septic plasma) activated isolated cardiac myocytes as evidenced by (1) increased nuclear levels of nuclear factor-κB (NF-κB) and (2) their ability to promote PMN migration across endothelial cell monolayers. Pretreatment of septic plasma with an antibody against tumor necrosis factor-α (TNF-α), but not interleukin-1β (IL-1β), blunted the ability of septic plasma to activate the myocytes. However, septic plasma obtained from TNF-α–deficient mice could still activate the myocytes; an effect attenuated by an antibody against IL-1β. If the myocytes were pretreated with a proteasome inhibitor (MG 132) to prevent NF-κB activation, the myocyte-induced PMN transendothelial migration was compromised. The activated myocytes released platelet-activating factor (PAF), and myocyte-induced PMN migration was abrogated by a PAF receptor antagonist (WEB 2086). These myocytes also released the CXC chemokines LIX and KC; an event prevented by MG 132. Antibodies against LIX and KC abrogated the myocyte-induced PMN migration. However, LIX and KC, but not PAF, could promote PMN migration when used at concentrations produced by activated myocytes. These observations indicate that TNF-α and IL-1β are, in part, responsible for the ability of septic plasma to activate cardiac myocytes. The activated myocytes promote PMN transendothelial migration, an effect attributable to LIX and KC, and possibly, PAF.
Relationship Between Carotid Artery Stiffness and Retinal Arteriolar Narrowing in Healthy Middle-Aged Persons
Authors: Liao Duanping , Wong Tien Yin , Klein Ronald , Jones Daniel , Hubbard Larry , Sharrett A. Richey
Published: March 2004

Background and Purpose—

Both carotid atherosclerosis and cerebral arteriolosclerosis are associated with stroke. However, the relationship between carotid atherosclerosis and cerebral arteriolosclerosis is unknown. We examined the association between carotid artery stiffness, a marker of early atherosclerosis, and retinal arteriolar narrowing, a marker of arteriolosclerosis, in healthy middle-aged people.

Methods—

This population-based, cross-sectional study involved 8031 men and women 45 to 64 years of age. Carotid arterial stiffness was estimated from high-resolution ultrasonic echo tracking of the left common carotid artery and was defined as adjusted arterial diameter change (AADC, μ, adjusted for diastolic blood pressure, pulse pressure and pulse pressure squared, and diastolic arterial diameter and height, with smaller AADC reflecting greater arterial stiffness). Generalized retinal arteriolar narrowing was estimated from measurements of diameters of retinal vessels from digitized retinal photographs and summarized as the arteriole-to-venule ratio (AVR, with smaller AVR indicating greater retinal arteriolar narrowing).

Results—

After controlling for age, sex, ethnicity, hypertension, diabetes, and cigarette smoking, decreasing AADC was associated with decreasing AVR. The mean AADCs, comparing the lowest and highest quartiles of AVR, were 394 (SE, 4) and 409 (SE, 4) μ, respectively (
P
<0.01). The pattern of the graded association between carotid arterial stiffness and generalized retinal arteriolar narrowing was similar among persons with and without hypertension.

Conclusions—

Greater stiffness of the carotid arteries is related to generalized narrowing of the retinal arterioles independent of blood pressure and other vascular factors. This supports a relationship between macrovascular and microvascular disease processes important in stroke pathogenesis.
Dual Role of Fcγ Receptor in Transient Focal Cerebral Ischemia in Mice
Authors: Komine-Kobayashi Miki , Chou Nei , Mochizuki Hideki , Nakao Atsuhito , Mizuno Yoshikuni , Urabe Takao
Published: March 2004

Background and Purpose—

Cerebral ischemia/reperfusion injury is associated with the development of inflammatory response, including pathological contributions by vascular leukocytes and endogenous microglia. Expression of Fc receptors (FcRs) on macrophages and microglia is thought to be involved in the inflammatory cascade. The present study assessed the role of FcγR in ischemia/reperfusion injury, using FcγR knockout (FcγR
−/−
) mice and bone marrow chimera FcγR
−/−
mice, which express enhanced green fluorescent protein (EGFP).

Methods—

Mice underwent occlusion of the middle cerebral artery for 60 minutes, followed by reperfusion. Infarct volume and mortality were calculated at several time points after ischemia. To clarify the function and distribution of microglia/macrophages, immunohistochemical staining and immunoblotting of ionized calcium-binding adapter molecule 1 (Iba-1), inducible nitric oxide synthase, and nitrotyrosine were performed.

Results—

FcγR
−/−
mice showed significantly reduced mortality (20%) and smaller infarcts (19.7±3.63 versus 33.28±7.98 mm
3
;
P
<0.001) than wild-type (WT) mice at 72 hours after reperfusion. Western blotting revealed that microglial activation (
P
<0.002) and induction of inducible nitric oxide synthase (
P
<0.005) were reduced in FcγR
−/−
mice compared with WT mice. At 7 days after reperfusion, sections double-immunostained for EGFP and Iba-1 showed less activation and migration of EGFP-positive bone marrow–derived macrophages in FcγR
−/−
chimera mice than in WT mice.

Conclusions—

Our results demonstrated that the neuroprotective effect of FcγR deficiency in our model may be primarily attributed to the suppression of activation and infiltration of inflammatory cells.
Nuclear Factor-κB Contributes to Infarction After Permanent Focal Ischemia
Authors: Nurmi Antti , Lindsberg Perttu J. , Koistinaho Milla , Zhang Wen , Juettler Eric , Karjalainen-Lindsberg Marja-Liisa , Weih Falk , Frank Norbert , Schwaninger Markus , Koistinaho Jari
Published: March 2004

Background and Purpose—

Activation of transcription factor nuclear factor-κB (NF-κB) may induce expression of either proinflammatory/apoptotic genes or antiapoptotic genes. Because a considerable number of middle cerebral artery occlusions (MCAOs) in humans are not associated with reperfusion during the first 24 hours, the role of NF-κB after permanent MCAO (pMCAO) was investigated.

Methods—

Mice transgenic for a NF-κB–driven β-globin reporter were exposed to pMCAO, and the expression of the reporter gene was quantified with real-time polymerase chain reaction. Mice lacking the p50 subunit of NF-κB and wild-type controls were exposed to pMCAO with or without treatment with pyrrolidinedithiocarbamate (PDTC), an NF-κB inhibitor. Brain sections of human stroke patients were immunostained for the activated NF-κB.

Results—

pMCAO increased NF-κB transcriptional activity to 260% (36.9±4.5 compared with 14.4±2.6; n=10;
P
<0.01) in the brain; this NF-κB activation was completely blocked by PDTC (17.2±2.6; n=9;
P
<0.05). In p50
−/−
mice, pMCAO resulted in 41% (18±3.2 mm
3
; n=12) smaller infarcts compared with wild-type controls (32.9±3.8 mm
3
; n=9;
P
<0.05), which was comparable to the protection achieved with PDTC in wild-type mice (19.6±4.2 mm
3
; n=8). Pro-DTC, a PDTC analogue that does not cross the blood-brain barrier, had no effect, even though Pro-DTC and PDTC were equally protective in vitro. During the first 2 days of human stroke, NF-κB was activated in neurons in the penumbral areas.

Conclusions—

NF-κB is induced in neurons during human stroke, and activation of NF-κB in the brain may contribute to infarction in pMCAO.
The Shape of Neural Dependence
Authors: Jenison Rick L. , Reale Richard A.
Published: March 2004

The product-moment correlation coefficient is often viewed as a natural measure of dependence. However, this equivalence applies only in the context of elliptical distributions, most commonly the multivariate gaussian, where linear correlation indeed sufficiently describes the underlying dependence structure. Should the true probability distributions deviate from those with elliptical contours, linear correlation may convey misleading information on the actual underlying dependencies. It is often the case that probability distributions other than the gaussian distribution are necessary to properly capture the stochastic nature of single neurons, which as a consequence greatly complicates the construction of a flexible model of covariance. We show how arbitrary probability densities can be coupled to allow greater flexibility in the construction of multivariate neural population models.
Estimating the Entropy Rate of Spike Trains via Lempel-Ziv Complexity
Authors: Amigó José M. , Szczepański Janusz , Wajnryb Elek , Sanchez-Vives Maria V.
Published: March 2004

Normalized Lempel-Ziv complexity, which measures the generation rate of new patterns along a digital sequence, is closely related to such important source properties as entropy and compression ratio, but, in contrast to these, it is a property of individual sequences. In this article, we propose to exploit this concept to estimate (or, at least, to bound from below) the entropy of neural discharges (spike trains). The main advantages of this method include fast convergence of the estimator (as supported by numerical simulation) and the fact that there is no need to know the probability law of the process generating the signal. Furthermore, we present numerical and experimental comparisons of the new method against the standard method based on word frequencies, providing evidence that this new approach is an alternative entropy estimator for binned spike trains.