bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversal of Angiogenic Growth Factor Upregulation by Revascularization of Lower Limb Ischemia
Authors: Porcu Paolo , Emanueli Costanza , Kapatsoris Maria , Chao Julie , Chao Lee , Madeddu Paolo
Published: July 2002

Background
—

Tissue kallikrein (tK) and vascular endothelial growth factor (VEGF) are potent angiogenic agents. Upregulation of tK or VEGF was documented in animal models of acute ischemia, yet it remains unknown whether these endothelial cell mitogens are overexpressed in chronic peripheral vascular insufficiency.

Methods and Results
—

Circulating tK and VEGF were measured in 36 patients with symptomatic peripheral vascular disease before and after surgical revascularization. In 6 patients without symptoms at rest, tK was assayed after exercise stress test. VEGF levels fell within the normal range in all patients (96±11 versus 109±13 pg/mL in healthy control subjects,
P
=NS) and remained unchanged after revascularization. In contrast, tK expression was upregulated in 34 of 36 patients (1107±203 versus 85±10 pg/mL in control subjects,
P
<0.05), with no further increase after exercise. Tissue kallikrein levels in the venous effluent of ischemic limbs were found to be positively correlated with the number of angiographically recognizable collateral vessels (
P
<0.001). Follow-up studies documented reversal of tK upregulation after revascularization (
P
<0.01), whereas no change was observed in venous samples from untouched legs.

Conclusions
—

Induction of tK could represent a compensatory response to chronic arterial insufficiency, attempting to maintain an adequate tissue perfusion. Heterogeneous statement of growth factors may have important implications in reparative and therapeutic angiogenesis.
New National Cholesterol Education Program III Guidelines for Primary Prevention Lipid-Lowering Drug Therapy
Authors: Fedder Donald O. , Koro Carol E. , L’Italien Gilbert J.
Published: July 2002

Background
—

The guidelines in the Third Report of the National Cholesterol Education Program (NCEP III) include absolute risk and lower LDL cholesterol (LDL-C) levels to assess eligibility for lipid-lowering drug therapy. We studied the impact of these changes on the size, sex, and age distribution of the target US population using data from the Third Annual National Health and Nutrition Survey (NHANES III) (1988 to 1994).

Methods and Results
—

A subsample of NHANES III participants aged 20 to 79 years with known cardiovascular risk factors and LDL-C levels was identified (n=13 589). We assessed their eligibility for drug therapy first using NCEP II guidelines and then using the new NCEP III criteria. We also calculated the number eligible for LDL-C lowering to <100 mg/dL. An estimated 15 million individuals aged 20 to 79 years are eligible for drug therapy under NCEP II; 51% are males, 49% are females, 26% are <45 years old, and 28% are ≥65 years old. Under NCEP III, 36 million would be eligible for treatment; 55% are males, 45% are females, 32% are <45 years old, and 27% are ≥65 years old. This represents a 140% increase in eligibility overall, a 157% increase among males, a 122% increase among females, a 131% increase among those ≥65 years old, and a 201% increase among those <45 years old. Of treatment-eligible individuals, 26% of males, 24% of females, 39% of elderly, and 14% of those <45 years old are targeted for LDL-C lowering to <100 mg/dL.

Conclusions
—

The NCEP III guidelines will alter the age and sex distributions of the treatment-eligible population, targeting many more younger (<45 years old) and greater numbers of elderly (≥65 years) individuals, particularly for aggressive intervention.
Social Environment Influences the Progression of Atherosclerosis in the Watanabe Heritable Hyperlipidemic Rabbit
Authors: McCabe Philip M. , Gonzales Julie A. , Zaias Julia , Szeto Angela , Kumar Mahendra , Herron Alan J. , Schneiderman Neil
Published: July 2002

Background

—

Although there is evidence that emotionally stressful behavior can accelerate the progression of atherosclerosis, there is less data to support the notion that affiliative social behavior can slow disease progression. The present study examines the influence of social environment on the progression of atherosclerosis in the Watanabe Heritable Hyperlipidemic (WHHL) rabbit, a model that spontaneously develops lesions because of a genetic defect in lipoprotein clearance.

Methods and Results

—

WHHL rabbits were assigned to 1 of 3 social or behavioral groups: an unstable group, in which unfamiliar rabbits were paired daily, with the pairing switched each week; a stable group, in which littermates were paired daily for the entire study; and an individually caged group. The stable group exhibited more affiliative social behavior and less agonistic behavior than the unstable group and significantly less aortic atherosclerosis than each of the other 2 groups. Although the unstable and individually caged groups had comparable aortic lesion areas, the severity of the disease progressed faster in the unstable group, as indexed by a larger area of calcification and increased fibrous cap thickness in complex lesions. The unstable group showed increased agonistic behavior and signs of chronic adrenocortical and gonadal activation, whereas the individually caged group was relatively sedentary, had low glucocorticoid levels, and was hyperinsulinemic compared with the other groups.

Conclusions

—

The present study demonstrates that social environment can slow, as well as accelerate, the progression of atherosclerosis. It also emphasizes the importance of behavioral factors in atherogenesis, even in a model of disease with strong genetic determinants.
Activation of Nuclear Factor-κB Significantly Contributes to Lumen Loss in a Rabbit Iliac Artery Balloon Angioplasty Model
Authors: Breuss J.M. , Cejna M. , Bergmeister H. , Kadl A. , Baumgartl G. , Steurer S. , Xu Z. , Koshelnick Y. , Lipp J. , De Martin R. , Losert U. , Lammer J. , Binder B.R.
Published: July 2002

Background

—

To investigate the contribution of inflammation to postangioplasty lumen loss, we used an adenoviral gene therapy approach to inhibit the central inflammatory mediator nuclear factor-κB (NF-κB) by overexpression of its natural inhibitor, IκBα.

Methods and Results

—

The adenovirus carrying human IκBα was applied immediately after balloon dilatation by a double-balloon catheter in a rabbit iliac artery restenosis model. Immunohistochemistry of IκBα revealed that mainly smooth muscle cells of the media but also cells of the adventitia were transduced and expressed the transgene IκBα for ≥8 days. At this time point, intercellular adhesion molecule-1 (30%) and monocyte chemotactic protein-1 (50%) expression, as well as recruitment of macrophages into the wounded area (90%), were significantly reduced in IκBα-treated vessels. In addition, expression of inhibitor of apoptosis proteins was reduced and the percentage of apoptotic cells was increased compared with control-treated contralateral vessels. Animals killed 5 weeks after treatment exhibited a significantly reduced degree of lumen narrowing (
P
<0.02) on the side treated with adenovirus IκBα. The lumen gain of ≈40% was due to positive remodeling.

Conclusions

—

From these data, we conclude that balloon angioplasty–induced activation of NF-κB contributes to lumen loss likely via induction of an inflammatory response and a decrease in the rate of apoptosis. These data show for the first time that inflammation mediated by NF-κB is involved in postangioplasty lumen narrowing. Specific and more potent inhibitors of NF-κB might therefore be a useful therapeutic measure to improve clinical outcome after balloon dilatation.
Value of Stress Myocardial Perfusion Single Photon Emission Computed Tomography in Patients With Normal Resting Electrocardiograms
Authors: Hachamovitch Rory , Berman Daniel S. , Kiat Hosen , Cohen Ishac , Friedman John D. , Shaw Leslee J.
Published: July 2002

Background
—

The incremental value and cost-effectiveness of stress single photon emission computed tomography (SPECT) is of unclear added value over clinical and exercise treadmill testing data in patients with normal resting ECGs, a patient subset known to be at relatively lower risk.

Methods and Results
—

We identified 3058 consecutive patients who underwent exercise dual isotope SPECT, who on follow-up (mean, 1.6±0.5 years; 3.6% lost to follow-up) were found to have 70 hard events (2.3% hard-event rate). Survival analysis used a Cox proportional hazards model, and cost-effectiveness was determined by the cost per hard event identified by strategies with versus without the use of SPECT. In this cohort, a normal study was associated with an exceedingly low hard-event rate (0.4% per year) that increased significantly as a function of the SPECT result. After adjusting for pre-SPECT information, exercise stress SPECT yielded incremental value for the prediction of hard events (χ
2
52 to 85,
P
<0.001) and significantly stratified patients. In patients with intermediate to high likelihood of coronary artery disease after exercise treadmill testing, a cost-effectiveness ratio of $25 134 per hard event identified and a cost of $5417 per reclassification of patient risk were found. Subset analyses revealed similar prognostic, and cost results were present in men, women, and patients with and without prior histories of coronary artery disease.

Conclusions
—

Stress SPECT yields incremental prognostic value and enhanced risk stratification in patients with normal resting ECGs in a cost-effective manner. These findings are opposite those of previous studies examining anatomic end points in this same population and thus, if confirmed, have significant implications for patient management.
Atrio-Sinus Interaction Demonstrated by Blockade of the Rapid Delayed Rectifier Current
Authors: Verheijck E. Etienne , Wilders Ronald , Bouman Lennart N.
Published: July 2002

Background
—

Proper pacemaking of the heart requires a specific organization of the sinoatrial (SA) node. The SA node drives the surrounding atrium but needs to be protected from its hyperpolarizing influence, which tends to suppress pacemaker activity. It has been suggested that the hyperpolarizing atrial influence is minimal at the site of the central nodal area.

Methods and Results
—

Atrio-sinus interaction was assessed by specific depolarization of the SA node by blocking the HERG-encoded rapid delayed rectifier current (I
K,r
) with the drug E-4031. In the SA node, E-4031 (1 μmol/L) changed action potential configuration drastically but never resulted in pacemaker arrest. In the atrium, E-4031 did not affect the membrane resting potential, thereby leaving the normal hyperpolarizing load on the SA node intact. When the SA node was sectioned into strips and subsequently separated from the atrium, spontaneous electrical activity of the strip containing the primary pacemaker ceased on I
K,r
blockade. When not separated from the atrium, I
K,r
blockade never resulted in pacemaker arrest. A similar effective atrio-sinus interaction was demonstrated in computer simulations.

Conclusions
—

Our results demonstrate that the atrium provides an effective hyperpolarizing load on the central SA nodal area and is at least one of the controlling mechanisms for normal pacemaking function. The present study can be of help in understanding why patients with long-QT2 syndrome secondary to a mutation in HERG do not show sinus arrest.
Aging Attenuates the Vestibulosympathetic Reflex in Humans
Authors: Ray Chester A. , Monahan Kevin D.
Published: July 2002

Background

—

The vestibular system contributes to sympathetic activation by engagement of the otolith organs. However, there is a significant loss of vestibular function with aging. Therefore, the purpose of the present study was to determine if young and older individuals differ in their cardiovascular and sympathetic responses to otolithic stimulation (ie, head-down rotation, HDR). We hypothesized that responses to otolithic stimulation would be attenuated in older adults because of morphological and physiological alterations that occur in the vestibular system with aging.

Methods and Results

—

Arterial blood pressure, heart rate, muscle sympathetic nerve activity (MSNA), and head rotation were measured during HDR in 11 young (26±1 years) and 11 older (64±1 years) subjects in the prone posture. Five older subjects performed head rotation (chin to chest) in the lateral decubitus position, which simulates HDR but does not alter afferent inputs from the vestibular system. MSNA responses to HDR were significantly attenuated in older as compared with young subjects (
P
<0.01). MSNA increased in the older subjects by only 12±5% as compared with 85±16% in the young. Furthermore, HDR elicited significant reductions in mean arterial blood pressure in older (Δ−6±1 mm Hg;
P
<0.01) but not young subjects (Δ1±1 mm Hg). In contrast to HDR, head rotation performed in the lateral decubitus position did not elicit hypotension. MSNA responses to baroreceptor unloading and the cold pressor test were not different between the age groups.

Conclusions

—

These data indicate that aging attenuates the vestibulosympathetic reflex in humans and may contribute to the increased prevalence of orthostatic hypotension with age.
Postischemic Recovery of Contractile Function is Impaired in SOD2
+/−
but Not SOD1
+/−
Mouse Hearts
Authors: Asimakis Gregory K. , Lick Scott , Patterson Cam
Published: July 2002

Background

—

Reactive oxygen species (ROS) contribute to myocardial stunning. Superoxide dismutase (SOD) is a major defense mechanism against ROS. The purpose of this study was to evaluate the contributions of cytosolic (SOD1) and mitochondrial (SOD2) isoforms to protect against myocardial stunning.

Methods and Results

—

Isolated hearts from wild-type, heterozygous (+/−) SOD1 and SOD2 knockout mice received 30 minutes of ischemia followed by 60 minutes of reperfusion. After 60 minutes of reperfusion, the heart rate multiplied by the developed pressure (HR×DP) in the wild-type and SOD1
+/−
hearts recovered to 92±9 and 85±7 of preischemic baseline values, respectively (
P
=NS). In contrast, the HR×DP was significantly lower (63±7%) in the SOD2
+/−
hearts compared with the wild-type hearts. Western blot analysis and enzymatic activity of tissue lysates confirmed reduction of activities of specific SOD isoforms without compensatory increase in the other isoform in the knockout animals studied.

Conclusions

—

Postischemic functional recovery is more sensitive to a partial deficiency of SOD2 than a partial deficiency of SOD1. Therefore, modulation of the mitochondrial SOD isoform is a critical determinant in the tolerance of the heart to oxidative stress.
Endogenous Ligand of α
1
Sodium Pump, Marinobufagenin, Is a Novel Mediator of Sodium Chloride–Dependent Hypertension
Authors: Fedorova Olga V. , Talan Mark I. , Agalakova Natalia I. , Lakatta Edward G. , Bagrov Alexei Y.
Published: July 2002

Background
—

Digitalis-like sodium pump ligands (SPLs) effect natriuresis via inhibition of renal tubular Na
+
,K
+
-ATPase but may induce vasoconstriction. The present study investigated the potential roles of 2 putative endogenous SPLs, an ouabain-like compound (OLC) and an α
1
Na
+
,K
+
-ATPase inhibitor, marinobufagenin (MBG), in regulating natriuresis and blood pressure (BP) responses to sustained and acute NaCl loading in Dahl salt-sensitive rats (DS).

Methods and Results
—

During 4 weeks of an 8% NaCl diet, DS exhibited a progressive increase in MBG renal excretion (66±13 pmol/24 hours at week 4 versus 11±1 pmol/24 hours at baseline, n=48), which paralleled an increase in systolic BP (174±10 mm Hg at week 4 versus 110±2 mm Hg at baseline). By contrast, OLC excretion peaked at week 1 and returned to baseline levels. Administration of an anti-MBG, but not anti-ouabain antibody, to DS after 3 weeks of a high NaCl diet lowered BP (139±7 versus 175±5 mm Hg,
P
<0.001, n=5). Acute NaCl loading (2 hours) of DS (n=5) increased MBG and OLC excretion and natriuresis. Pretreatment of acutely NaCl-loaded DS with an anti-MBG antibody (n=5) reduced the excretion of sodium and MBG but not that of OLC. An anti-ouabain antibody (n=5) reduced sodium excretion and both OLC and MBG.

Conclusions
—

An initial transient stimulation of OLC induced by NaCl loading of DS precedes an MBG response. A sustained increase in MBG production in DS contributes to the chronic BP elevation induced by a sustained high NaCl intake.
Selective Upregulation of Endothelin B Receptor Gene Expression in Severe Pulmonary Hypertension
Authors: Bauer Michael , Wilkens Heinrike , Langer Frank , Schneider Sven O. , Lausberg Henning , Schäfers Hans-Joachim
Published: July 2002

Background
—

The pulmonary circulation is an important site for the production and clearance of endothelin (ET)-1, a potent vasoactive and mitogenic peptide. Increased plasma ET-1 levels are observed in pulmonary arterial hypertension (PHT) and may contribute to the regulation of pulmonary vascular resistance, as well as to proliferative changes in the pulmonary vascular bed.

Methods and Results
—

We prospectively assessed changes in plasma big ET-1 levels and changes in ET
A
and ET
B
receptor gene expression in 14 consecutive patients undergoing pulmonary thromboendarterectomy for thromboembolic PHT. Plasma big ET-1 levels were higher in patients with PHT (median, 2.2 pg/mL; 25th to 75th percentile, 1.5 to 3.0 pg/mL) compared with age-matched controls (median, 1.2 pg/mL; 25th to 75th percentile, 1.0 to 1.4 pg/mL;
P
=0.002). In addition to increased plasma big ET-1 levels, selective upregulation of ET
B
receptor mRNA transcripts and immunoreactive protein in the pulmonary artery was observed in the patients; however, ET
A
receptor gene expression was unaffected.

Conclusions
—

These data suggest that changes in the ET signaling system in PHT caused by thromboembolic disease are not limited to an increased production of ET-1: they also affect ET receptor gene expression.
Vascular Origin of a Soluble Truncated Form of the Hepatocyte Growth Factor Receptor (c-met)
Authors: Wajih Nadeem , Walter Jennifer , Sane David C.
Published: July 2002

Hepatocyte growth factor (scatter factor) is an angiogenic growth factor that binds to its cellular transmembrane receptor, c-met. Both HGF and c-met are expressed by vascular smooth muscle and endothelial cells, where HGF may exert autocrine and paracrine effects. We have found that human aortic smooth muscle cells (HASMCs) and human umbilical vein endothelial cells (HUVECs) release a soluble, truncated form of c-met. Receptor shedding was induced by treatment of the cells with phorbol 12-myristate 13-acetate (PMA) and by the ligand, HGF. Shedding was inhibited by cycloheximide, a metalloproteinase inhibitor, and protein kinase C inhibitors. The soluble form of c-met was able to bind HGF, although with reduced affinity (K
d
≈10 nmol/L) compared with the membrane bound receptor. Conditioned medium containing soluble c-met inhibited the induction of Akt phosphorylation by HGF in HUVECs. The soluble truncated form of c-met was detectable in the plasma of 5 healthy volunteers. The shedding of c-met may represent a novel mechanism for regulating the mitogenic, motogenic, and morphogenic effects of hepatocyte growth factor.
Expression and Intracellular Localization of an

SCN5A

Double Mutant R1232W/T1620M Implicated in Brugada Syndrome
Authors: Baroudi Ghayath , Acharfi Said , Larouche Chantal , Chahine Mohamed
Published: July 2002

Brugada syndrome is an inherited cardiac disorder caused by mutations in the cardiac sodium channel gene,
SCN5A,
that leads to ventricular fibrillation and sudden death. This study reports the changes in functional expression and cellular localization of an
SCN5A
double mutant (R1232W/T1620M) recently discovered in patients with Brugada syndrome. Mutant and wild-type (WT) human heart sodium channels (hNa
v
1.5) were expressed in tsA201 cells in the presence of the β
1
-auxiliary subunit. Patch-clamp experiments in whole-cell configuration were conducted to assess functional expression. Immunohistochemistry and confocal microscopy were used to determine the spatial distribution of either WT or mutant cardiac sodium channels. The results show an abolition of functional sodium channel expression of the hNa
v
1.5/R1232W/T1620M mutant in the tsA201 cells. A conservative positively charged mutant, hNa
v
1.5/R1232K/T1620M, produced functional channels. Immunofluorescent staining showed that the FLAG-tagged hNa
v
1.5/WT transfected into tsA201 cells was localized on the cell surface, whereas the FLAG-tagged hNa
v
1.5/R1232W/T1620M mutant was colocalized with calnexin within the endoplasmic reticulum (ER). These results indicate that a positively charged arginine or lysine residue at position 1232 in the double mutant is required for the proper transport and functional expression of the hNa
v
1.5 protein. These results support the concept that loss of function of the cardiac Na
+
channel is responsible for the Brugada syndrome. The full text of this article is available at http://www.circresaha.org.
Cardiac-Specific Expression and Hypertrophic Upregulation of the Feline Na
+
-Ca
2+
Exchanger Gene H1-Promoter in a Transgenic Mouse Model
Authors: Müller Joachim G. , Isomatsu Yukihisa , Koushik Srinagesh V. , O’Quinn Michael , Xu Lin , Kappler Christiana S. , Hapke Elizabeth , Zile Michael R. , Conway Simon J. , Menick Donald R.
Published: July 2002

The NCX1 gene contains three promoters (H1, K1, and Br1), and as a result of alternative promoter usage and alternative splicing, there are multiple tissue-specific variants of the Na
+
-Ca
2+
exchanger. We have proposed that for NCX1, the H1 promoter regulates expression in the heart, the K1 promoter regulates expression in the kidney, and the Br1 promoter regulates expression in the brain as well as low-level ubiquitous expression. Here, using a transgenic mouse model, we test the role of the DNA region including −1831 to 67 bp of intron 1, encompassing exon H1 of the feline NCX1 gene (NCX1H1). The NCX1H1 promoter was sufficient for driving the normal spatiotemporal pattern of NCX1 expression in cardiac development. The luciferase reporter gene was expressed in a heart-restricted pattern both in early embryos (embryonic days 8 to 14) and in later embryos (after embryonic day 14), when NCX1 is also expressed in other tissues. In the adult, no luciferase activity was detected in the kidney, liver, spleen, uterus, or skeletal muscle; minimal activity was detected in the brain; and very high levels of luciferase expression were detected in the heart. Transverse aortic constriction–operated mice showed significantly increased left ventricular mass after 7 days. In addition, there was a 2-fold upregulation of NCX1H1 promoter activity in the left ventricle in animals after 7 days of pressure overload compared with both control and sham-operated animals. This work demonstrates that the NCX1H1 promoter directs cardiac-specific expression of the exchanger in both the embryo and adult and is also sufficient for the upregulation of NCX1 in response to pressure overload.
Essential Role of the NADPH Oxidase Subunit p47
phox
in Endothelial Cell Superoxide Production in Response to Phorbol Ester and Tumor Necrosis Factor-α
Authors: Li Jian-Mei , Mullen Adrian M. , Yun Sheng , Wientjes Frans , Brouns Gabi Y. , Thrasher Adrian J. , Shah Ajay M.
Published: July 2002

A phagocyte-type NADPH oxidase complex is a major source of endothelial reactive oxygen species (ROS) production, but its biochemical function and regulation remain unclear. In neutrophils, the p47
phox
subunit is centrally involved in oxidase activation in response to agonists such as phorbol-12-myristate-13-acetate (PMA). We investigated the role of p47
phox
in endothelial cell ROS production in response to PMA or tumor necrosis factor-α (TNFα) stimulation. To specifically address the role of p47
phox
, we studied coronary microvascular endothelial cells (CMECs) isolated from p47
phox−/−
mice and wild-type controls. p47
phox
was absent in hearts of knockout mice whereas the essential oxidase subunit, p22
phox
, was expressed in both groups. In the absence of agonist stimulation, the lack of p47
phox
did not result in a reduction in NADPH-dependent ROS production in p47
phox−/−
CMECs compared with wild-type CMECs. Prestimulation with PMA (100 ng/mL) or TNFα (100 U/mL) for 10 minutes significantly increased NADPH-dependent O
2
−
production in wild-type CMECs, assessed either by lucigenin (5 μmol/L) chemiluminescence or dichlorohydrofluorescein (DCF) fluorescence. This response was completely lost in p47
phox−/−
cells. Transfection of the full-length p47
phox
cDNA into p47
phox−/−
CMECs caused expression of p47
phox
protein and restoration of the O
2
−
response to PMA and TNFα. In wild-type CMECs, transfection of antisense p47
phox
cDNA substantially reduced p47
phox
expression and caused loss of the O
2
−
response to PMA and TNFα. These data show that endothelial cell p47
phox
is critical in the upregulation of NADPH oxidase activity by PMA and TNFα.
Adenoviral-Directed Expression of the Type 1A Angiotensin Receptor Promotes Cardiomyocyte Hypertrophy via Transactivation of the Epidermal Growth Factor Receptor
Authors: Thomas Walter G. , Brandenburger Yves , Autelitano Dominic J. , Pham Thao , Qian Hongwei , Hannan Ross D.
Published: July 2002

Angiotensin II (Ang II) may cause cardiac hypertrophy via type 1 Ang II receptors (AT
1
) on cardiomyocytes and through growth factors released from cardiac fibroblasts. Whereas cardiomyocyte-specific AT
1
receptor expression produces cardiac hypertrophy and remodeling in vivo, delineation of the signals that mediate growth to Ang II is challenging because the prevailing in vitro model (cultured neonatal cardiomyocytes) expresses low levels of AT
1
receptor and responds inconsistently to Ang II. In this study, when AT
1A
receptors were expressed using adenovirus in cultured neonatal cardiomyocytes, Ang II stimulated a robust hypertrophy that was not secondary to the release of cardiac fibroblast-derived factors, specifically endothelin-1. Hypertrophy was accompanied by the induction of the immediate-early response genes,
c-fos
and
c-jun
, and reexpression of atrial natriuretic peptide (ANP). Ang II–induced activation of an ANP promoter-reporter was inhibited by the dominant/negative mutants, GαqI and N17Ras, indicating that hypertrophic signaling by the AT
1A
receptor is via heterotrimeric G protein coupling and downstream Ras pathways. AT
1A
-mediated cardiomyocyte hypertrophy and mitogen-activated protein kinase (MAPK) activation were inhibited by the MAPK kinase inhibitor, PD98059, and the epidermal growth factor (EGF) receptor kinase antagonist, AG1478, but not by PKC inhibitor, bisindolylmaleimide-1. Moreover, Ang II–induced MAPK activation was prevented by treatment with a matrix metalloproteinase inhibitor, consistent with the tyrosine phosphorylation of the EGF receptor in response to AT
1A
receptor activation. These data unequivocally demonstrate that Ang II can directly promote cardiac myocyte growth via AT
1A
receptors expressed on these cells and reveal for the first time the important contribution of EGF receptor–transactivated MAPK signaling to this process.
p38 Mitogen-Activated Protein Kinase Mediates a Negative Inotropic Effect in Cardiac Myocytes
Authors: Liao Pu , Wang Shi-Qiang , Wang Su , Zheng Ming , Zheng Meizi , Zhang Sheng-Jun , Cheng Heping , Wang Yibin , Xiao Rui-Ping
Published: July 2002

p38 Mitogen-activated protein kinase (MAPK) is one of the most ancient signaling molecules and is involved in multiple cellular processes, including cell proliferation, cell growth, and cell death. In the heart, enhanced activation of p38 MAPK is associated with ischemia/reperfusion injury and the onset of heart failure. In the present study, we investigated the function of p38 MAPK in regulating cardiac contractility and its underlying mechanisms. In cultured adult rat cardiomyocytes, activation of p38 MAPK by adenoviral gene transfer of an activated mutant of its upstream kinase, MKK3bE, led to a significant reduction in baseline contractility, compared with uninfected cells or those infected with a control adenoviral vector (Adv-β-galactosidase). The inhibitory effect of MKK3bE on contractility was largely prevented by coexpressing a dominant-negative mutant of p38 MAPK or treating cells with a p38 MAPK inhibitor, SB203580. Conversely, inhibition of endogenous p38 MAPK activity by SB203580 rapidly and reversibly enhanced cell contractility in a dose-dependent manner, without altering L-type Ca
2+
currents or Ca
2+
i
transients. MKK3bE-induced p38 activation had no significant effect on pH
i
, whereas SB203580 had a minor effect to elevate pH
i
. Furthermore, activation of p38 MAPK was unable to increase troponin I phosphorylation. Thus, we conclude that the negative inotropic effect of p38 MAPK is mediated by decreasing myofilament response to Ca
2+
, rather than by altering Ca
2+
i
homeostasis and that the reduced myofilament Ca
2+
sensitivity is unlikely attributable to troponin I phosphorylation or alterations in pH
i
. These findings reveal a novel function of p38 MAPK and shed a new light on our understanding of the coincidence of p38 MAPK activation and the onset of heart failure.
Imbalance Between Xanthine Oxidase and Nitric Oxide Synthase Signaling Pathways Underlies Mechanoenergetic Uncoupling in the Failing Heart
Authors: Saavedra Walter F. , Paolocci Nazareno , St. John Marcus E. , Skaf Michel W. , Stewart Garrick C. , Xie Jin-Sheng , Harrison Robert W. , Zeichner Joshua , Mudrick Daniel , Marbán Eduardo , Kass David A. , Hare Joshua M.
Published: July 2002

Inhibition of xanthine oxidase (XO) in failing hearts improves cardiac efficiency by an unknown mechanism. We hypothesized that this energetic effect is due to reduced oxidative stress and critically depends on nitric oxide synthase (NOS) activity, reflecting a balance between generation of nitric oxide (NO) and reactive oxygen species. In dogs with pacing-induced heart failure (HF), ascorbate (1000 mg) mimicked the beneficial energetic effects of allopurinol, increasing both contractility and efficiency, suggesting an antioxidant mechanism. Allopurinol had no additive effect beyond that of ascorbate. Crosstalk between XO and NOS signaling was assessed. NOS inhibition with
N
G
-monomethyl-
l
-arginine (L-NMMA; 20 mg/kg) had no effect on basal contractility or efficiency in HF, but prevented the +26.2±3.5% and +66.5±17% enhancements of contractility and efficiency, respectively, observed with allopurinol alone. Similarly, improvements in contractility and energetics due to ascorbate were also inhibited by L-NMMA. Because of the observed NOS-XO crosstalk, we predicted that in normal hearts NOS inhibition would uncover a depression of energetics caused by XO activity. In normal conscious dogs, L-NMMA increased myocardial oxygen consumption (MV̇O
2
) while lowering left ventricular external work, reducing efficiency by 31.1±3.8% (
P
<0.005). Lowered efficiency was reversed by XO inhibition (allopurinol, 200 mg) or by ascorbate without affecting cardiac load or systemic hemodynamics. Single-cell immunofluorescence detected XO protein in cardiac myocytes that was enhanced in HF, consistent with autocrine signaling. These data show that both NOS and XO signaling systems participate in the regulation of myocardial mechanical efficiency and that upregulation of XO relative to NOS contributes to mechanoenergetic uncoupling in heart failure.
Gene Transfer of Endothelial NO Synthase and Manganese Superoxide Dismutase on Arterial Vascular Cell Adhesion Molecule-1 Expression and Superoxide Production in Deoxycorticosterone Acetate-Salt Hypertension
Authors: Li Lixin , Crockett Elahe , Wang Donna H. , Galligan James J. , Fink Gregory D. , Chen Alex F.
Published: July 2002

Enhanced vascular cell adhesion molecule-1 (VCAM-1) expression directly contributes to vascular dysfunction in hypertension. Decreased NO and/or increased superoxide are causative factors for such an event in the vessel wall. The present study was undertaken to determine whether gene transfer of endothelial NO synthase (eNOS) or manganese superoxide dismutase (MnSOD) affects VCAM-1 levels in arteries from hypertensive rats. Isolated carotid and femoral arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats were transduced for 4 hours with adenoviral vectors encoding eNOS, MnSOD, or β-galactosidase reporter genes. Recombinant eNOS or MnSOD expression was evident morphologically and quantitatively 24 hours after gene transfer. Immunohistochemistry, ELISA, and Western blot techniques were used to determine VCAM-1 expression and levels. In addition, endogenous eNOS and MnSOD and in situ superoxide levels were analyzed by immunoblotting and fluorescence confocal microscopy, respectively. Arterial VCAM-1 expression was significantly higher in DOCA-salt hypertensive rats than in sham-operated rats; this expression was accompanied by decreased MnSOD but unaltered endogenous eNOS levels. VCAM-1 expression was significantly lower in MnSOD- and eNOS-transduced hypertensive arteries, with a concomitant reduction of superoxide level. These results suggest that gene transfer of MnSOD or eNOS suppresses arterial VCAM-1 expression in DOCA-salt hypertension by reducing the superoxide level.
Cerebral Blood Flow Restoration and Reperfusion Injury After Ultraviolet Laser–Facilitated Middle Cerebral Artery Recanalization in Rat Thrombotic Stroke
Authors: Watson Brant D. , Prado Ricardo , Veloso Alexander , Brunschwig J-P. , Dietrich W. Dalton
Published: July 2002

Background and Purpose

—

A reversible model of focal thrombotic stroke was developed in the rat and examined for histological evidence of reperfusion injury after clinically relevant times of recanalization.

Methods

—

The distal middle cerebral artery of 28 male Sprague-Dawley rats was occluded by 562-nm laser-driven photothrombosis for 0.5, 2, and 3 hours or permanently (each n=7) and was recanalized by 355-nm UV laser irradiation. Occlusive material was examined by transmission electron microscopy. Cortical cerebral blood flow was monitored by laser-Doppler flowmetry. Brain infarcts were examined histologically at 3 days.

Results

—

After occlusion, cortical cerebral blood flow was reduced to 33±4% of baseline for all groups and was restored to 82±9%, 75±3%, and 93±7% of baseline for the 0.5-, 2-, and 3-hour groups, respectively, following recanalization after 29±8, 38±20, and 70±33 minutes of UV laser irradiation. The thrombotic occlusion contained compactly aggregated platelets but no fibrin, with length (1.2 to 1.8 mm) proportional to the ischemic period. During recanalization, microchannels containing erythrocytes and scattered leukocytes and bordered by intact disaggregated platelets infiltrated the thrombus. Infarct volumes (mm
3
) at 3 days were 12±3 for the permanent case and 8±4, 24±3, and 30±9 for the 0.5-, 2-, and 3-hour cases, respectively, thus demonstrating reperfusion injury histologically in the latter 2 groups. No hemorrhage was seen.

Conclusions

—

UV laser–facilitated dissolution of a conventionally refractory platelet thrombus provides a novel and effective method for restoring blood flow without hemorrhagic complications during thrombotic stroke. This was the first observation of histologically confirmed reperfusion injury in such a model.
Prolonged Cerebral Transit Time in CADASIL
Authors: Liebetrau Martin , Herzog Jürgen , Kloss Christian U.A. , Hamann Gerhard F. , Dichgans Martin
Published: July 2002

Background and Purpose

—

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary angiopathy caused by mutations in
Notch3
. Cerebral microvessels show an accumulation of granular osmophilic material in the vicinity of degenerating vascular smooth muscle cells. In this study, we measured the arteriovenous cerebral transit time (CTT) to identify changes related to the microangiopathy in CADASIL.

Methods

—

CTT is the time that a contrast agent needs to pass from a cerebral artery to its corresponding vein. CTT was measured in 17 CADASIL individuals (mean age, 50.2±12.3 years) and an equal number of age- and sex-matched control subjects (mean age, 48.9±13.0 years) with transcranial color-coded duplex sonography. The intensity curves were recorded in the P2 segment of the posterior cerebral artery and the vein of Galen after injection of the ultrasound contrast agent Levovist.

Results

—

CTT was significantly prolonged in individuals with CADASIL (4.4±1.9 seconds) compared with control subjects (1.3±0.5 seconds,
P
<0.0001). This difference was also significant when only nondisabled CADASIL individuals (Rankin score=0, n=9) were analyzed (
P
<0.0001). There was a nonsignificant trend for a correlation between Rankin score and CTT (
r
=0.39,
P
=0.11).

Conclusions

—

The prolonged CTT likely reflects microvascular changes in CADASIL. Measurements of the CTT may be used clinically to disclose small-vessel disease. Studies comparing CADASIL subjects with other patient populations seem warranted to determine possible differences in CTT between different types of small-vessel disease.
Abrogated Leptin-Induced Cardiac Contractile Response in Ventricular Myocytes Under Spontaneous Hypertension
Authors: Wold Loren E. , Relling David P. , Duan Jinhong , Norby Faye L. , Ren Jun
Published: July 2002

Leptin regulates cardiovascular function. Leptin levels are elevated in obesity and hypertension and may play a role in cardiovascular dysfunctions in these comorbidities. This study was designed to determine the influence of hypertension on the cardiac contractile response of leptin. Mechanical and intracellular Ca
2+
properties were evaluated using an IonOptix system in ventricular myocytes from spontaneously hypertensive (SHR) and age-matched Wistar Kyoto (WKY) rats. The contractile properties included peak shortening (PS), duration and maximal velocity of shortening/relengthening (TPS/TR
90
, ±dL/dt), and fura-fluorescence intensity change (ΔFFI). NO and nitric oxide synthase (NOS) activity were assessed by the Griess and the
3
H-arginine/citrulline conversion assays, respectively. The leptin receptor (Ob-R) and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway were evaluated by Western blot analysis. SHR animals displayed significantly elevated blood pressure and plasma leptin levels. Leptin elicited a concentration-dependent inhibition of PS and ΔFFI in WKY, but not in SHR myocytes. Leptin did not affect TPS, TR
90
, or ± dL/dt. The difference in leptin-induced contractile response between the WKY and the SHR groups was abolished by the NOS inhibitor, Nω-nitro-
l
-arginine methyl ester (L-NAME), but not by elevated extracellular Ca
2+
. Either the JAK2 inhibitor AG-490 or the mitogen-activated protein (MAP) kinase inhibitor SB203580 abrogated the leptin-induced response in the WKY myocytes, whereas AG-490 unmasked a negative response in PS in the SHR myocytes. SHR myocytes displayed similar Ob-R protein abundance and basal NO levels, a blunted leptin-induced increase in NOS activity as well as enhanced basal STAT3 levels compared with the WKY group. These data indicate that the leptin-induced cardiac contractile response is abolished by spontaneous hypertension, possibly because of mechanisms involving altered JAK/STAT, MAP kinase signaling, and NO response.
Coexistence of Hypercholesterolemia and Hypertension Impairs Adventitial Vascularization
Authors: Kai Hisashi , Kuwahara Fumitaka , Tokuda Keisuke , Shibata Rei , Kusaba Ken , Niiyama Hiroshi , Tahara Nobuhiro , Nagata Tsuyoshi , Imaizumi Tsutomu
Published: July 2002

We have shown that adventitial vasa vasorum (AVV) formation is enhanced in hypertensive rat aorta to compensate hypoxia in the thickened media and that hypercholesterolemia impairs angiogenesis in rat ischemic hindlimb. Thus, we examined the effects of coexistence of hypercholesterolemia and hypertension on AVV formation. In Wistar rats, hypercholesterolemia was established by high-cholesterol diet from Day −14 (HC rats), and hypertension was induced by a suprarenal aortic constriction at Day 0 (HT rats). At Day 28, we studied AVV density, adventitial area, and medial thickness in the ascending aorta of control (standard diet+sham operation), HC, HT, and HC+HT rats (n=5/group). In HC rats, although the adventitial area was modestly increased, the AVV density and medial thickness were unchanged versus controls. In addition to medial thickening, marked enlargement of the adventitial area accompanied by increased AVV density was observed in HT rats, compared with controls. HC+HT rats showed lower AVV density, despite larger adventitial area, than HT rats, whereas the medial thickness was similar in HT and HC+HT rats. Immunohistostaining revealed hypoxia-inducible factor-1α expression in the media only in HC+HT rats but not in the other 3 groups, suggesting persistent medial hypoxia in HC+HT rats. In conclusion, it is suggested that coexistence of hypercholesterolemia and hypertension impairs AVV formation, resulting in insufficient compensation for hypoxia in the thickened media. Our findings provide an insight into the mechanism of the aggravation of arteriosclerosis when both hypercholesterolemia and hypertension are present.
Nitric Oxide, Anti-Inflammatory Drugs on Renal Prostaglandins and Cyclooxygenase-2
Authors: Miyataka Masaru , Rich Kathryn A. , Ingram Marylou , Yamamoto Tadahiko , Bing Richard J.
Published: July 2002

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used as analgesics. They inhibit cyclooxygenases (COX), preventing the formation of prostaglandins, including prostacyclin and thromboxane. A serious side effect of COX-1 and COX-2 is renal damage. We report here that both a nonselective NSAID (aspirin, acetylsalicylic acid) and COX-2 selective NSAIDs (celecoxib and NS-398) diminished renal prostacyclin and thromboxane concentration in the renal medulla. NSAIDs failed to change COX-2 and iNOS (the inducible form of NO synthase) expression. A NO donor, B-NOD, preserved renal prostacyclin and thromboxane after administration of aspirin. PGI
2
and COX-2 protein were mainly expressed in the renal medulla, whereas iNOS expression was greater in the cortex. B-NOD preserved renal prostacyclin levels after administration of NSAIDs.
Inflammatory Cytokines Stimulate Adrenomedullin Expression Through Nitric Oxide–Dependent and –Independent Pathways
Authors: Hofbauer Karl-Heinz , Schoof Ellen , Kurtz Armin , Sandner Peter
Published: July 2002

A body of evidence indicates that the production of adrenomedullin (ADM) in vivo is activated in states of inflammation. Our aim was to characterize the intracellular signaling pathways along which inflammation leads to a stimulation of ADM expression. For this purpose, we characterized the effects of inflammatory cytokines, tumor necrosis factor-α (100 μg/L), interleukin-1β (20 μg/L), and interferon-γ (0.5 U/L) on ADM gene expression in rat aortic vascular smooth muscle cells (AVSMCs). We found that inflammatory cytokines induced a time-dependent 12-fold upregulation of ADM mRNA in AVSMCs that was paralleled by a substantial increase in inducible NO synthase mRNA expression. The stimulatory effect of cytokines on ADM gene expression was attenuated by NO deprivation induced by
Nω
-nitro-
l
-arginine methyl ester (1 mmol/L) and was in part mimicked by the NO donor
S
-nitroso-
N
-acetylpenicillamine (100 μmol/L). The cGMP analog 8-bromo-cGMP (100 μmol/L) had no effect on ADM gene expression, and inhibition of cGMP production by 1H-oxodiazolo-quinoxalin-1 (ODQ, 200 μmol/L) was not able to abrogate the increase of ADM mRNA induced by NO donation using
S
-nitroso-
N
-acetylpenicillamine (100 μmol/L). The significant induction of ADM gene expression by inflammatory cytokines and NO donation was also observed in mesangial cells, endothelial cells, and hepatocytes. These findings suggest that NO is a direct activator of ADM gene expression in a variety of cell types and that inflammatory cytokines stimulate ADM expression via both NO-dependent and -independent mechanisms. The stimulatory effect of NO appears to not be related to the classic guanylate cyclase–cGMP pathway.
Gene Transfer of cGMP-Dependent Protein Kinase I Enhances the Antihypertrophic Effects of Nitric Oxide in Cardiomyocytes
Authors: Wollert Kai C. , Fiedler Beate , Gambaryan Stepan , Smolenski Albert , Heineke Jörg , Butt Elke , Trautwein Christian , Lohmann Suzanne M. , Drexler Helmut
Published: July 2002

NO acting through soluble guanylyl cyclase and cGMP formation is a negative regulator of cardiomyocyte hypertrophy. Downstream targets mediating the inhibitory effects of NO/cGMP on cardiomyocyte hypertrophy have not been elucidated. In addition to its antihypertrophic effects, NO promotes apoptosis in cardiomyocytes, presumably through cGMP-independent pathways. We investigated the role of cGMP-dependent protein kinase (PKG) in the antihypertrophic and proapoptotic effects of NO. Incubation of neonatal rat cardiomyocytes with the NO donor
S
-nitroso-
N
-acetyl-
d
,
l
-penicillamine (SNAP) (250 μmol/L) or the PKG-selective cGMP analog 8-pCPT–cGMP (500 μmol/L) activated endogenous PKG type I, as shown by the site-specific phosphorylation of vasodilator-stimulated phosphoprotein, a well-characterized PKG substrate. SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) modestly attenuated the hypertrophic response to α
1
-adrenergic stimulation with phenylephrine. Although a high concentration of SNAP (1000 μmol/L) promoted apoptosis in cardiomyocytes, as evidenced by the formation of histone-associated DNA fragments, antihypertrophic concentrations of SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) did not promote cell death. Because chronic activation downregulated endogenous PKG I, we explored whether gene transfer of PKG I would enhance the sensitivity of cardiomyocytes to the antihypertrophic effects of NO/cGMP. Indeed, after adenoviral overexpression of PKG Iβ, SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) completely suppressed the hypertrophic response to α
1
-adrenergic stimulation. As observed in noninfected cells, SNAP (250 μmol/L) and 8-pCPT–cGMP (500 μmol/L) did not promote apoptosis in cardiomyocytes overexpressing PKG Iβ. Moreover, overexpression of PKG Iβ did not enhance the proapoptotic effects of 1000 μmol/L SNAP, implying PKG-independent effects of NO on apoptosis. Endogenous PKG I mediates antihypertrophic but not proapoptotic effects of NO in a cell culture model of cardiomyocyte hypertrophy. Adenoviral gene transfer of PKG I selectively enhances the antihypertrophic effects of NO without increasing the susceptibility to apoptosis.
In the Shadow of Law or Power? Consensus-Based Bargaining and Outcomes in the GATT/WTO
Authors: Steinberg Richard H.
Published: July 2002

This article explains how consensus decision making has operated in practice in the General Agreement on Tariffs and Trade/World Trade Organization (GATT/WTO). When GATT/WTO bargaining is law-based, consensus outcomes are Pareto-improving and roughly symmetrical. When bargaining is power-based, states bring to bear instruments of power that are extrinsic to rules, invisibly weighting the process and generating consensus outcomes that are asymmetrical and may not be Pareto-improving. Empirical analysis shows that although trade rounds have been launched through law-based bargaining, hard law is generated when a round is closed, and rounds have been closed through power-based bargaining. Agenda setting has taken place in the shadow of that power and has been dominated by the European Community and the United States. The decision making rules have been maintained because they help generate information used by powerful states in the agenda-setting process. Consensus decision making at the GATT/WTO is organized hypocrisy, allowing adherence to the instrumental reality of asymmetrical power and the sovereign equality principle upon which consensus decision making is purportedly based.